CONTROL OF VOC EMISSIONS FROM NONFERROUS METAL ROLLING PROCESSES

CONTROL TECHNOLOGY CENTER

SPONSORED BY:

Emission Standards Division Office of Air Quality Planning and Standards

U.S. Environmental Protection Agency Research Triangle Park, North Carolina 27711

Air and Energy Engineering Research Laboratory Office of Research and Development

U.S. Environmental Protection Agency Research Triangle Park, North Carolina 27711

June 4992

EPA-453/R-92-001 June 1992

CONTROL OF VOC EMISSIONS FROM NONFERROUS METAL ROLLING PROCESSES

Prepared by:

W. Scott Snow Philindo J. Marsosudiro

Alliance Technologies Corporation 100 Europa Drive, Suite 150

Chapel Hill, North Carolina 27514 i

EPA Contract No. 68-DO-0121 Work Assignment No. 1-30 (Alliance No. 1-638-030-1)

Project Officer

Joseph Myers Emission Standards Division

U.S. Environmental Protection Agency Research Triangle Park, North Carolina 27711

Prepared for:

Control Technology Center U.S. Environmental Protection Agency

Research Triangle Park, North Carolina 27711

DISCLAIMER

This final report was prepared for the Control Technology Center, U.S. Environmental

Protection Agency, by Alliance Technologies Corporation, 100 Europa Drive, Chapel Hill, NC

27514, in partial fulfiUment of Contract No. 68-DO-0121, Work Assignment No 1-30. The

opinions, findings and conclusions expressed are those of the authors and not necessarily those

of the Environmental Protection Agency.

... 1ll

PREFACE

This report was prepared for and funded by the Control Technology Center (CTC) of the

U.S. Environmental Protection Agency. The CTC was established by EPA’s Office of Research

and Development (ORD) and Office of Air Quality Planning and Standards (OAQPS) to provide

technical assistance to State and local a i r pollution control agencies. Several levels of assistance

are available through the CTC: a CTC HOTLINE provides telephone assistance on matters

relating to air pollution control technology; in-depth engineering assistance is provided when

needed by EPA and its contractors; and the CTC can provide technical guidance through

publication of technical guidance documents, development of personal computer software, and

presentation of workshops on control technology matters. The fourth assistance pro,oram

spqnsored by the CTC is the CTC Bulletin Board System (BBS), a part of the EPA OAQPS

Technology Transfer Network. Users of the BBS can retrieve CTC information through one of

four major area menu selections. The four areas included are Utilities, Help Center,

Documents/Software, and CTC Projects.

Technical guidance projects, such as this one, foeus on topics of national or regional

interest that are identified through contact with State and local agencies. In this case, the CTC

received a number of calls on controlling volatile organic compound (VOC) emissions from

nonferrous metal rolling processes. Controlling VOC emissions at various source types that have

not been addressed by Control Techniques Guidelines ( (XG’s ) is of interest to many States and

local air pollution control agencies due to on-going ozone nonattainment problems (VOC is a

precursor of ozone) and requirements in Title I of the Clean Air Act Amendments of 1990. This

report presents the results of a study to identify and collect information on nonferrous metal

rolling processes and the VOC emissions generated during these operations.

iv

b

TABLE OF CONTENTS

Section Page ...

Disclaimer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . m Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iv ListofFigures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vii List of Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vm ...

1 INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1

2 PROCESS DESCRIPTION AND VOC EMISSIONS SOURCES . . . . . . . . . . . . 2-1 2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1 2.2 Nonferrous Rolling Industry Structure . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1

2.2.1 Market Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2 2.2.2 Raw Materials. Products. and Product End-uses . . . . . . . . . . . . . . 2-2 2.2.3 Profile of Aluminum and Copper Rolling Facilities . . . . . . . . . . . . 2-3 2.2.4 RollingMillTypes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3

2.3 Rolling Process Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . '2-4 2.3.1 2.3.2 Hot Rolling Process Equipment . . . . . . . . . . . . . . . . . . . . . . . . . 2-8 2.3.3 Deformation Theory and Heat Generation . . . . . . . . . . . . . . . . . . 2-8

2.4 Rolling Mill VOC Emissions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-9 2.4.1 Types of Lubricants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-9 2.4.2 Lubricant Application Techniques . . . . . . . . . . . . . . . . . . . . . . . 2-11 2.4.3 Physical Properties of Various Rolling Lubricants . . . . . . . . . . . . 2-12 2.4.4 Sources of Lubricant Loss and Make-up . . . . . . . . . . . . . . . . . . 2-14 2.4.5 Factors Affecting the Level of Emissions . . . . . . . . . . . . . . . . . . 2-17 2.4.6 Degradation of Rolling Lubricant . . . . . . . . . . . . . . . . . . . . . . . 3-19 2.4.7 Current Emissions Controls in the Rolling Industry . . . . . . . . . . . 2-19

2.5 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-21

Cold Rolling Process Equipment . . . . . . . . . . . . . . . . . . . . . . . . . 2-4'

3 VOC EMISSION CONTROL TECHNIQUES . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1 3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1 3.2 Capture Systems for Nonferrous Rolling Mills . . . . . . . . . . . . . . . . . . . . 3-1 3.3 Control Devices for Nonferrous Rolling Mills . . . . . . . . . . . . . . . . . . . . . 3-2

3.3.1 Carbon Adsorption . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4 3.3.2. Absorption (Scrubbing) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-6 3.3.3 Incineration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-7

3.4 Lubricant Substitution (Source Reduction) . . . . . . . . . . . . . . . . . . . . . . . 3-9 3.4.1 Emission Reduction Mechanisms of Lubricant Substitution . . . . . 3-10 3.4.2 Applicability of Lubricant Substitution to Rolling Process . . . . . . 3-11 3.4.3 Applicability of Lubricant Substitution as a Control Method . . . . 3-13

V

TABLE OF CONTENTS (Continued)

Section Page

3.4.4 Summary of Lubricant Substitution Advantages and Disadvantages ..................................... 3-14

3.5 Process and Equipment Modifications ......................... 3-14 3.5.1 Process Modifications for Potential VOC Emission Reduction . . . 3-16 3.5.2 Equipment Modifications for Potential VOC Emission Reduction . 3-17

3.6 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-19

4 CONTROL COST ANALYSIS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1 4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1 4.2 VOC Add-on Control Devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1

4.2.1 Carbon Adsorption . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-3 4.2.2 Absorption (Scrubbing) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-3 4.2.3 Thermal Incineration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-3 4.2.4 Catalytic Incineration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-10

4.3 Lubricant Substitution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-10 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.5 References 4-16

APPENDIX ATRIPREPORTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-1

. .

vi

LIST OF FIGURES

I Number Page

Schematic Diagram of Metal Deformation Process on a Two-High Mill . . . . . . . . 2-5

Schematic Diagram of a Four.High. Single Stand Nonferrous Rolling Mill . . . . . . 2-6

Sources of Lubricant Loss and Input in a Nonferrous Rolling Mill . . . . . . . . . . 2-16

2-1

2-2

2-3

3-1 Typical Rolling Mill Stand Capture System . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-3

V i i

I

LIST OF TABLES

Number Page

2-1 Typical Lubricants for Nonferrous Metal Rolling. . . . . . . . . . . . . . . . . . . . . . . 2-10

2-2 Important Lubricant Properties . . . . . . . . . . . . . . . . . . . . . . . . . . , . . . . . . . . 2-13

3-1 Summary of Advantages and Disadvantages of Lubricant Substitution Experience in the Aluminum Foil Rolling Industry . . . . . . . . . . . . . . . . . . . . . 3-15

4-1 General Parameters and Cost Factors For Estimating Costs for Add-on ControlDevices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2

4-2 Operating and Labor Requirements Used to Estimate Annual Costs for Fluidized-Bed Carbon Adsorption . . . . . . . . . . - . . . . . . . , . . . . . . . . . . . ~ . . . 4-4

4-3 Capital and Annual Costs for Fluidized-Bed Carbon Adsorption . . . . . . . . . . . . . 4-5

4-4 Operating and Labor Requirements Used to Estimate Annual Costs for Oil Adsorption . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . _ . . . . . . . . . . . . . 4-6

4-5 Capital and Annual Costs for Oil Absorption . . . . . . . . . . . . . . . . . . . . . . . . . . 4-7

f3 4-6 Operating and Labor Requirements Used to Estimate Annual Costs for

Thermal and Catalytic Incinerators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-8

4-7 Capital and Annual Costs for Thermal Incineration . . . . . . . . . . . . . . . . . . . . . . 4-9

4-8 Capital and Annual Costs for Catalytic Incineration . . . . . . . . . . . . . . . . . . . . . 4- 11

4-9 General Assumptions and Cost Factors Used to Derive Lubricant Substitution Cost Impact. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-12

4-10 Example Calculation of Annual Cost for Lubricant Substitution . . . . . . . . . . . . 4-14

4-11 Annual Costs for Lubricant Substitution at Various Lubricant Use Reductions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . 4- 15

... vu1

CHAPTER 1

INTRODUCTION

This report presents the results of a study to collect and report information on nonferrous

metal rolling processes, volatile organic compound (VOC) emissions generated during these

operations, emission control techniques and their effectiveness, and costs associated with process

changes and emission control options. State agencies and other government-sponsored programs,

as well as equipment manufacturers, professional and trade organizations, and nonferrous metal

rolling facilities were contacted to assess production methods, current emission controls used in

the industry, and available control technologies for nonferrous rolling processes.

Many nonferrous metal rolling operations exist in the United States today, however,

aluminum and copper are the two largest industries. There are approximately 55 facilities

engaged in aluminum rolling operations and 23 facilities producing copper rolled products. Most

aluminum facilities are located in the South and Midwest while copper facilities are found mainly

in the North and Midwest. It has been estimated that half of these plants are located in ozone

. nonattainment areas.

This report is divided into four chapters and one appendix. Chapter 2 characterizes the

nonferrous metal l'olling industry's market structure, mw materials, products, and mill types. It

provides a description of the rolling processes, process equipment, and lubricants used during the

rolling processes. Chapter 2 also provides a discussion of process VOC emission sources within

a nonferrous rolling mill and the current emissions controls being utilized in the industry.

Chapter 3 discusses methods of reducing and controlling VOC emissions resulting from

nonferrous rolling mill operations. Areas addressed include add-on control devices, process and

equipment modifications, improved operating practices, and source reduction methods. Chapter

4 estimates the capital and annual costs associated with add-on control devices and source

reduction methods.

This report also includes an appendix that contains copies. of the trip reports for the two

nonferrous metal rolling facilities visited during the course of this work assignment.

1- 1

CHAPTER 2

PROCESS DESCRIPTION AND VOC EMISSIONS SOURCES

2.1 INTRODUCTION

This chapter gives an overview of the nonferrous metal rolling industry including market

structure, process descriptions, and volatile organic compound (VOC) emissions sources. The

EPA defines a VOC as any organic compound that participates in atmospheric photochemical

reactions. Compounds designated as having negligible photochemical reactivity are exempt from

regulation. VOC emissions from nonferrous rolling mills result from the use of lubricants

containing hydrocarbon compounds in the rolling process. While a variety of nonferrous metals

are included in the rolling industxy, the primary focus of this document is on the two major

nonferrous metal rolling operations: aluminum and copper.

The nonferrous rolling industry can be broken down by type of nonferrous metal rolled

and type of rolling, hot or cold. General process descriptions are given based on the type of

rolling mill employed (two-high, four-high, continuous, etc.). Sources of VOC emissions are

identified, and available information on emissions levels from those sources are given.

.

2.2 NONFERROUS ROLLING INDUSTRY STRUCTURE

In general, a "nonferrous metal rolling mill" is defined as a process machine for the gauge

reduction or forming of nonferrous metals by exerting pressure between rotating rolls.' The

nonferrous metal rolling industry consists of rolling facilities producing nonferrous plate, sheet,

smp, and/or foil. In related rolling industries nonferrous rod and bar are produced. These

facilities are not addressed in this report because rod and bar are produced by hot rolling ingot2

using a water-based coolant that produces little or no VOC emissions. The nonferrous metals

category includes aluminum, copper, lead, zinc, refractory metals, magnesium, nickel, tin,

titanium, and zirconium. This section describes the nonferrous metal rolling industry in terms

of the market, raw materials, processes, rolling mill types, products, and product uses,

2- 1

2.2.1 Market Structure

The U.S. Government Standard Industrial Classification (SIC) coding system has several

categories which include nonferrous metal rolling. SIC codes 3351, 3353, and 3356 contain

nonferrous metal rolling among other types of metal manufacturing. Copper sheet, plate, and

strip production are included in SIC code 3351, along with copper drawing and extruding: which

are not within the scope of this report. Aluminum sheet, plate, and foil production fall under SIC

code 3353; however, SIC code 3353 also includes establishments producing aluminum welded

tube which are not relevant to this report? Other nonferrous metal rolling is included in SIC

code 3356; however, this is a broad category which includes all nonferrous metal rolling (except

aluminum and copper), drawing, and extruding operations.’ As stated before, drawing and

extruding processes are not relevant to this report. Industry sources indicate that the other main

types of nonferrous metal rolling, besides aluminum and copper, are lead and Another

minor category (SIC code 3497) includes nonferrous metal foil and leaf fabri~ation.~

Bureau of the Census data indicate that a total of 55 establishments in the U.S. were

engaged in aluminum rolling operations with a combined production rate of approximately 5.12

million tons (10.24 billion pounds) in 1987. There were also 23 copper rolling facilities in the

U.S. producing approximately 0.59 million tons (1.18 billion pounds) of copper rolled products

in 1987. The only other nonferrous metal rolling data available were for lead with eight (8)

locations in the U.S. producing approximately 31.6 million pounds of rolled lead product.

Geographically, the aluminum rolling industry is concentrated in the South and Midwest, while

copper rolling facilities are found mainly in the North and Midwest. Other nonferrous rolling

operations are spread fairly evenly across the United States.’

consumer.

2.2.2 Raw Materials, Products, and Product End-uses

Two main types of raw materials are employed in the nonferrous rolling process: metal

or metal alloy and lubricant. Initially, metal in the form of ingots manufactured by primary or

secondary producers undergoes hot rolling, using a water-based lubricant,6 which reduces these

ingots to plate and heavy-gauge sheet sizes. These plates and sheets then undergo cold rolling,

2-2

which typically uses a petroleum-based lubricant for the production of light-gauge sheet and smp

or foil.

Finished rolled products have a wide variety of uses. They may be further fabricated to

produce package foil, food wrap, lining material or containers. In addition, sheet metal may

undergo forming and bending operations to produce decorative pieces, tubes, cones, etc.

Nonferrous sheet is also used in building and construction and in automobiles?'

2.2.3 Profile of Aluminum and Copper Rolling Facilities

This report focuses on the two most prominent types of nonferrous metal rolling

operations in the U.S. today: aluminum and copper. Although industries are relatively similar,

there are some dissimilarities in plant functions and types of products rolled. i

a The aluminum rolling industry is divided among plants that perform both hot and cold

rolling, those that engage in foil (cold) rolling,' and those that continuously cast.' Hothold

rolling facilities directly reduce aluminum ingot to plate and sheet, while foil rolling mills reduce '

sheet to foil thicknesses. Aluminum plate is defined to be greater than 7.25 inches in thickness,

sheet is defined as between 0.006 and 0.245 inches in thickness and aluminum foil is defmed as

less than 0.006 inches thick."

,

The copper rolling industry is similar in structure to aluminum given that certain facilities

perform both hot and cold rolling, while other facilities perform cold rolling only. Hot rolling

reduces copper ingots to a sheet size of about 0.25 inches. Cold rolling reduces the gauge further

to smp thicknesses of usually not less than 0.004 inches.

2.2.4 Rolling Mill Types

Rolling mills include several different types: tandem mills, cluster mills, Sendzmir mills,

and continuous casters. A tandem mill consists of a number of stands spaced closely together

in one continuous line. In a cluster mill, each end of the two working rolls is supported by two

or more backing rolls (six-high mill); this type of mill is mainly used for rolling thin materials.

A Sendzmir mill is a relatively new design and features several different roll arrangements

designed to roll very thin foils or strips. Also fairly new is the continuous caster which has made

2-3

it possible to directly convert molten metal into thin rolled products thereby eliminating the

various intermediate steps.g

2.3 ROLLING PROCESS DESCRIPTION

Rolling operations are mechanically similar for both aluminum and copper. The primary

purpose of a nonferrous metal rolling operation is to reduce the gauge (thickness) of the metal

work piece and form it into a useful shape? The two basic types of rolling processes are hot and

cold rolling which are used in most nonferrous rolling industries. As stated previously, hot

rolling reduces metal ingots to medium gauge where further reduction takes place via cold rolling

to strip, foil, and light-gauge sheet sizes. This section discusses both hot and cold rolling

processes and the equipment employed during those operations.

2.3.1 Cold Rolling Process Equipment

The primary equipment used to cold roll nonferrous metal includes a two- or four-high

rolling stand, work rolls, back-up rolls (four-high mill), drive motors, roll bending and gap

adjustment hydraulic systems, and the coiVrecoi1 and core handling systems. More modem mills

contain gauge and shape controls.’ One set of this equipment constitutes a mill stand.

A schematic diagram of the deformation process on a two-high mill is illustrated in

Figure 2-1. Two-high simply means that metal is deformed between two steel work rolls.

Figure 2-2 illustrates a four-high single stand (Le., one set of rolls) mill along with auxiliary

equipment.2 The four-high rolling stand represents a special kind of two-high roller where

backup rolls are used to reinforce the smaller working rolls. These four-high mills resist the

tendency of long working rolls to deflect and thus permit the rolling of wider sheets and very

small thicknes~es.~

The work rolls are arranged vertically while the nonferrous metal is fed horizontally into

the mill at speeds ranging from 180 to 2,400 meters per minute (600 to 8,000 “in).‘’ The roll

force is supplied by the work rolls (via drive motor) perpendicular to the surface of the metal.

The frictional forces that develop between the rolls and the work piece carry the rolled product

through the mill?

2-4

i

! I

Mill Input 5

i

1 Mill O u i p u i -

Nonferrous Metal ?!ate. Sheet, Strip or Foil i

Figure 2-1. Schematic diagram of metal deformation process on a two-high

2-5

- 0 W Y

'I

a CI 3

3 4

0

ti

L

I

kr L W = LL .-

I

k. d L

L 0

E a L co a J .- u .- a

2-6

Deformation occurs in two dimensions such that the work piece is flattened and elongated

but not widened during the rolling process. The work rolls are typically 0.76 meters (30 inches)

to 1.27 meters (50 inches) wide regardless of the mill type. The diameter of the work rolls,

however, is variable. The diameter of the work rolls for a typical two-high mill is approximately

0.61 meters (24 inches) and for a four-high mill is between 0.25 meters (10 inches) and 0.36

meters (14 inches). The diameter of the back-up rolls for a four-high mill is approximately 0.76

meters (30 inches).2

CoiVrecoil equipment is provided for each rolling mill to feed the work rolls on the

entrance side and recoil the rolled product on the exit side (see Figure 2-2). Tension is applied

to the work piece during the rolling operation to reduce the mechanical load required for

deformation. The temperature of the metal during each of the cold rolling steps is maintained

below about 100°C (212OF) by the application of a hydrocarbon-based lubricant/coolant. The

lu6ricant serves to keep the rolls cool and minimize friction between the rolls and work piece.

The lubricant is supplied in excess, and the overflow is collected, cooled, and filtered before

being recycled?

$

There are several stages to the rolling operation. The nonferrous metal ingot is first sent

to a breakdown 'mill where it is hot rolled, which is designed to achieve maximum thickness

reduction per mill pass (50 to 65 percent).'" When the metal has been reduced to the

intermediate-gauge coiled sheet via further hot or cold rolling, it is sent to finishing mills where

it is cold rolled to final product. Finishing mills improve the surface quality and accomplish the

final thickness reduction of the nonferrous metal. Finished rolls are machined and polished to

a narrow dimensional tolerance and bright finish. In the production of very thin foil (aluminum

foil, for example), two layers of metal are often rolled simultaneously on the last pass through

the finishing mill (pair rolling).2

After the rolling process is complete, the cold rolled metal is sent to an annealing oven.

The purpose of annealing is to relieve the strain hardening induced by the cold rolling process

and to vaporize or burn off any residual lubricant present on the coiled roll. This is

accomplished by heating the nonferrous metal above its recrystallization temperature allowing

new grain growth in the metal's microstructure? Typically, copper is annealed at temperatures

over 600°C (1100°F) while aluminum is annealed at temperatures in excess of 400°C (750°F).6

2-7

Lubricants are usually chosen so that their 90 percent distillation endpoint is exceeded

during annealing, allowing most of the residual oil to vaporize from the metal surface. The net

result of the annealing process is an oil-he product with improved ductility properties. This

annealed product is then either cut to size and packaged or shipped elsewhere for further

fabrication?

2.3.2 Hot Rolling Process Equipment

The process equipment used to hot roll nonferrous metal is generally the same as that

used in cold rolling. There are, however, two major differences between hot and cold rolling.

The first is that hot rolling is performed above the recrystallization temperature of the alloy being

processed. This provides a more ductile material allowing for greater thickness reduction of I

metal ingots. The second difference involves the lubricant used in the rolling process. Either

no lubricant (dry rolling) or, more typically, an oil in water emulsion (normally one to five

percent)6 functions as the lubricant rather than a mineral oil.

2.33 Deformation Theory and Heat Generation

The use of rolling lubricant/coolant is required for most nonferrous metals due to the

amount of friction and heat generated at the roll nip or roll bite. Friction is generated between

the metal and the work rolls during the rolling process. A small amount of friction is required

to keep the metal moving through the mill; however, excessive friction can cause the metal to

adhere to the work rolls. Lubricants are designed to eliminate excessive friction and provide an

adequate amount to keep the roll moving. Heat is generated at the roll bite via mechanical

deformation stresses that occur in the metal from the rolling process. The lubricant is designed

to remove this excess heat.

Cold rolling lubricants are designed to maintain the roll bite temperaewe below 100°C

(212'F). Generally, hot rolling does not generate excessive heat because internal stresses created

during rolling are relieved at the high initial temperatures of the metal. Excessive friction,

however, may induce the need for lubrication in such oxidation prone nonferrous metals as

aluminum. In this case, an oil in water emulsion is required to prevent sticking. For some

2-8

metals such as copper, dry hot rolling is viable. In most cases, however, oil in water emulsions

are used to protect the steel work rolls from excessive temperatures.6

2.4 ROLLING MILL VOC-EMISSIONS

Several sources of VOC emissions may exist in a rolling mill as a result of lubrication.

These include emissions associated with lubricative metal rolls during rolling operations, fugitive

losses associated with storage and transfer of rolling lubricants, and equipment lubricant losses

in gearboxes, bearings, etc. The lubricants used can be categorized as either high or low viscous

oils. High viscosity oils are typically employed to control wear in gearboxes, back-up and work

rolls and other bearings, and drive spindles. The lower viscosity oils are used mainly for rolling

operations to prevent contact between the surface of the work rolls and metal, and to take away

thk heat generated by friction and metal deformation. The rolling lubricant or oil is the main

potential source of voc emissions resulting from rolling operations? This section contains a

description of various rolling lubricants, their physical properties and characteristics, application

techniques, and the sources and factors effecting lubricant losses.

i

2.4.1 Types of Lubricants

As stated previously, most rolling processes require some type of lubricant/coolant The

function of the lubricant varies by metal but most often it is used to dissipate heat and prevent

sticking of the metal to the steel work rolls. Hot rolling processes generally use oil in water

emulsions, steam, or no lubricant at all (dry Cold rolling lubricants, however, can

vary significantly from metal to metal and from individual mill to individual mill.’.” A summary

of the typical base lubricants used in rolling mills by nonferrous metal type is given in Table 2- 1.

Lubricants employed in the nonferrous metal rolling industry can be classified as either

a water-based emulsion or a mineral oil. Another viable option for some nonferrous metal rolling

operations, especially hot rolling, is the use of no lubricant (dry rolling).” This section also

discusses lubricant additives which may be used in both lubricant categories.

2-9

TABLE 2-1. TYPICAL LUBRICANTS FOR NONFERROUS METAL ROLLING'S-'6

Metal and Its Alloys Cold Hot Aluminum MO (4-20) with 1-5% Emulsion, 2-15%

fatty acid, alcohol, ester

Foil: as above but MO acid, alcohol, ester

concentration of MO (20-100) with 6 0 % fatty

(1.5-6) Copper Emulsion, 2- 10% Emulsion, 2-8%

concentration of MO (80-400) with fat

concentration of MO (80-400) with fat

MO (8-50) with fat Dry Magnesium same as Aluminum same as Aluminum Refractory Metals MO with boundary and MO with EP additives

\ EP agents Dry

Titanium Oxidized surface, with Dry esters of soap, castor oil (fatty oil) and compounded MO (4- 10)

Fat and water

MO - mineral oil; viscosity in cSt at 40°C in parentheses. J3 - extreme pressure additives.

2.4.1.1 Water- based Emulsions

Oil in water ( O m emulsions contain oil in the dispersed (internal) phase with water as

the continuous (external) phase. Emulsions are regarded as having three principal components:

the oily phase, the emulsifier, and water. The oily phase contains the mineral oil and, depending

on the application, required additives such as animal or vegetable fats, fatty oils, and soap.15

Emulsifiers are surface-active substances (surfactants) that reduce interfacial tension between

water and oil allowing them to become emu1sified.l6 Water must be appropriately treated and

cleaned to avoid adverse affects on emulsion stability." These oil in water emulsions are, for

the most part, restricted to hot rolling operations, but are being improved for possible use in cold

rolling applications .

2-10

2.4.1.2 Mineral Oils

As previously discussed, mineral oils may be used in the oily phase of an oil in water

emulsion; however, they may also be used as the primary constituent especially in cold rolling

applications. Mineral oils are mixtures of hydrocarbons obtained mostly from crude oil by

distillation. Their properties depend on chain length, structure, and degree of r e f ~ g . As the

number of carbon atoms per molecule (chain length) increases so do viscosity, flash point, fire

point, boiling point and volatility. Mineral oils can be refined to remove impurities such as

waxes, aromatic compounds, and sulfur compounds. Super-refined mineral oils are closer to

synthetic oils in purity, but there is no best mineral oil for all nonferrous metal rolling.”

2.4.1.3 Lubricant Additives i

Few of the water-based or mineral oil lubricants fulfill all the requirements of a metal

rolling lubricant. Almost all lubricants require additives to impart other properties of a non-

lubrication nature such as oxidation resistance, and corrosion protection. Selecting the correct

additives for the job is the function of the industrial oil chemist. Boundary, extreme-pressure

(EP), solid and other general additives each serve a different purpose in improving the quality

of the rolling lubricant. It should be noted, however, that some additives could be detrimental

to the metal being rolled.”

.

Boundary additives include fatty acids, fatty esters, fatty oils, and soap detergents. Fatty

acids and the like, in quantities as small as 0.1 percent, have been shown to reduce friction in

the working of aluminum. Ep additives provide viscosity protection of the lubricant in its

working temperature range. General additives include oxidation inhibitors, corrosion inhibitors,

detergents, and defoaming agents.”

2.4.2 Lubricant Application Techniques

Several types of lubricant application techniques are used in the nonferrous rolling

industry, including spraying, dripping, and flooding. The application method chosen by a specific

mill depends on the type of metal being rolled, the type of mill used, and the mill rolling speed.2

2-11

Air jets are typically used to distribute the lubricant (whether oil or water base) to appropriate

areas to perform both cooling and l~brication.’~ Mill operators commonly adjust the lubricant

flow rate to achieve particular degrees of product quality?

In general, high-speed mills require larger amounts of lubricant due to the increased heat

and friction generatd2 Flooding techniques under high-pressure application are good for this

requirement. Slower rolling speeds do not require as much lubricant and therefore may use low-

pressure spray or drip application. Proponents of high-pressure application claim that

impingement on the roll and strip surfaces helps to break up a stagnant layer of lubricant or

steam and thus increases heat transfer. Adherents of low-pressure application regard quantity of

lubricant and wetting as more important, with the additional benefit of less misting; this is

currently the preferred method of the nonferrous rolling industry.15 The application system must

ensure that lubricant is supplied in sufficient quantities, uniformly over the entire strip surface.

A sufficient quantity of lubricant must be available to cany away a minimum of 75 percent of

all heat generated. Rolling oils are typically applied to the roll at rates from 1,500 to 3,000

liters/min per meter of width of rolled strip at pressures ranging from 150 to 1,OOO kPa.”

i

After being applied to the rolls, spent lubricant is drained into a rolling mill pit where it

is either disposed of or replenished and recycled. Lubricant lifetimes can range anywhere from

three months to two years. After the lubricant’s lifespan is reached, it can be burned in a plant

boiler, sold at reduced cost as a fuel oil, or sent offsite for treatment and disposal or recycling.‘

2.4.3 Physical Properties of Various Rolling Lubricants

Physical propemes of the rolling lubricant are the major determining factor in choosing

a particular lubricant for a mill. Important propemes pertaining to the rolling process include

the boiling range, viscosity, and flash point. Important properties pertaining to potential VOC

emissions (also somewhat important to the rolling process) include specific heat, heat of

vaporization, and vapor pressure? These properties for three average types of rolling mill

lubricants are given in Table 2-2.

An important property to the rolling process is the boiling range of the lubricant The

boiling range of a lubricant must be lower than the temperatures obtained during the rolling

process. Another important property to the rolling process is viscosity. Gauge reduction will

2-12

I

TABLE 2-2. IMPORTANT LUBRICANT PROPERTIES

Lubricant Physical Property C,, Linear

Kerosene Mineral Oil Paraffin Rolling Properties Boiling Range - O C (OF) Initial Boiling Point 174 (346) Final Boiling Point 264 (508)

Viscosity - cst at 38°C (100OF) 2.5 Flash Point

"C (OF)

49 - 82 (120 - 180)

Emissions Level yroperties Specific Heat

J/kg-K 2,093 (BTU/lb-OF) (0.50)

Heat of Vaporization at 66OC (150°F) Jk 256

(BT'UPb) (1 10)

" H g 1.2 Vapor Pressure at 38°C (100OF)

254 (490) 226 (438) 321 (610) 242 (468)

4.5 1.93

2,03 1 2,303 (0.485) (0.55)

22 1 323 (95) (139)

0.02 0.7

typically increase, and surface finish will decrease with higher viscosity. For this reason,

functionally different mills require different rolling lubricants. For breakdown mills, where gauge

reduction is more important than surface finish, high viscosity lubricants may be used. At

fmishing mills, the surface finish is more important, and, therefore, low viscosity lubricants are

preferred? It should be noted that the physical propemes of any base lubricant can be altered

with additives.

Flammability characteristics of lubricants are measured by the lubricant flash point? The

flash point of an oil is the lowest temperature at which that oil will give off sufficient vapor to

ignite momentarily upon application of a flame.12 Therefore, a lower flash point constitutes more

of a fue hazard; additives, however, can be used to increase the flash point of any lubricant.

2-13

The two major factors contributing to the level of VOC emissions are the heat removal

capability of the oil and the volatility of the oil. The properties associated with heat removal

capacity are; the specific heat and the heat of vaporization.2 A higher specific heat implies that

more energy must be consumed to raise the temperature of a substance. A high heat of

vaporization also means that more energy is required to vaporize the material. Therefore, a

rolling lubricant with high values for each of these would be preferred from an emissions

reduction standpoint.

The volatility of a lubricant depends primarily on its vapor pressure. Vapor pressure

varies with both temperature and type of hydrocarbons present in the lubricant.2 A lower vapor

pressure implies a larger number of carbon atoms (higher molecular weight) in the oil entailing

a lower rate of evaporization. Thus, a higher molecular weight rolling oil would be preferred to

reduce the vaporization of the lubricant. The drawback to this is that higher molecular weight

implies higher viscosity12 reducing the practicality of the coolant at foil rolling mills where low

viscosity oils are preferred for better surface finish and faster production speeds.

Each property discussed above varies by lubricant type and thus will vary by metal

industry and within a metal industry depending upon its application. Differences in aluminum

and copper lubricants are a prime example of this. Aluminum lubricants are typically lower in

viscosity than any other nonferrous rolling industry except magnesium." Lower viscosity implies

a shorter chain length resulting in a higher vapor pressure and lower heat capacity. Copper

lubricants are typically two to three times as viscous as aluminum oil.^'^*^^ implying a lower vapor

pressure and greater heat capacity. How these properties affect emissions is further discussed

in Section 2.4.5.

2.4.4 Sources of Lubricant Loss and Make-up

VOC emissions from nonferrous metal rolling facilities result from several sources of roll

coolant loss and make-up. Emissions are either in the form of a vapor or an aerosol. The

aerosoVvapor split is an important factor when considering applicability of various add-on control

devices.2 The vapor/aemsol split tends to vary with the test method used to obtain the

i n f o m a t i ~ n . * ~ Data obtained by a major manufacturer indicate that between 5 and 50 percent of

the total aluminum rolling mill emissions may be in the aerosol form. However, other aluminum

2- 14

industry specialists believe that the majority of mill emissions are in the vapor phase? One test

conducted for brass and copper mills concluded that 80 percent of the hydrocarbon emissions

we- aerosol with the remaining 20 percent in the vapor form.2o

Emissions to the atmosphere are difficult to quantify because of the many factors that

affect lubricant inputs and losses at a given mill. Figure 2-3 shows the various routes of

lubricant input losses inputs in a typical rolling mill. Lubricant losses can be qualitatively

distributed between the following pathways:

0 oil vaporized at the roll bite

e residual lubricant carried out on metal, eventually vaporized or burned off during annealing

e lubricaht spilled or splashed on floor

0 lubricant vaporized f?om supply sump

e sump lubricant losses to overflow drain’

These losses are balanced by three main input sources of lubricant:

e make-up lubricant supply to the sump

0 equipment oil leaks to the sump

0 residual lubricant on the incoming metal coil’

Vaporization of lubricant at the roll bite is the main source for VOC emissions at cold

rolling mills. It has been estimated that as much as 70 percent or as little as 20 percent of mill

emissions are captured by existing hoods and ductwork, the remainder comprising fugitive

emissions? Also, little information exists on the magnitude of oil vaporization at the roll bite

where the largest fraction of heat generated is dissipated2

2- 15

Roof or Control System 'I

I \ Unwind I Roll 81

I

I /Capture Hood

\Rind <w' 1 Roll \LJ

/ a \

Pump

\ \ I ? i Oil SUED I

= ; I 'I '\ c . i C

------ Losses

I I

i C

A - O u t on Foil B - Out Stack C - Splash onto Floor D - Evaporation from Sump E - Loss to Sump Overflow Drain

L

t C

Inputs

F - In Foil G - Make-up Oil io Sump H - Equipment Leaks

Figure 2-3. Sources of lubricant loss and input in a nonferrous rolling mill.

2- 16

2.45 Factors Affecting the Level of Emissions

Several rolling mill operational factors can affect the level of VOC emissions from any

given mill. Each factor can generally be classified as either a mill parameter or a lubricant

parameter. Both of these types of factors are discussed in this section.

Mill operating parameters determine the mount of coolant required to obtain the desired

rolled product. These parameters include:

e mill production rate (mill speed)

magnitude of gauge reduction per pa e S

type of mill (breakdown, finishing, etc.)

face velocity of the capture hood (if existent) 1

e

The first three mill parameters are interrelated. Mill production rate, gauge reduction, and mdl

type aLl determine the amount of heat and friction generated at the roll bite. In turn, this

determines the required operating temperature of the lubricant oil. Additionally, these three

parameters determine the amount of lubricant required for adequate cooling. Higher heat

generation requires more lubricant and thus more potential for VOC emissions.2 Therefore, for

the same metal, high-speed rolling mills with large gauge reductions per pass would be expected

to have higher VOC emissions rates than lower speed mills with less gauge reduction.

The affect of gas velocity at the capture hood is also a consideration for VOC emissions.

High face velocities would be expected to increase the amount of oil droplet entrainment in the

exhaust gas stream reducing the chance for lubricant recovery/recycling and increasing the

relative amount of VOC emissions? Therefore, the gas velocity of the capture hood should be

designed to minimize this excess oil entrainment, thus reducing the amount of VOC emissions.

The following lubricant parameters determine to what extent the mill operating parameters

can be met:

e type of lubricant used (see Table 2-1)

2- 17

a physical and chemical propemes of the base oil and lubricant additives (see Table 2-2)

0 method of oil application and application rate

0 lubricant operating temperature

The type of lubricant used is a function of the metal being rolled and at what stage the metal is

in production. Thus, the metal being rolled determines many of the mill and lubricant parameters

that are responsible for emissions levels. Lubricant type and lubricant properties are highly

influenced by product specifications. Lubricant properties most relevant to emissions levels are

vapor pressure, boiling point range, specific heat, and heat of vaporization (all these were

discussed previously). Lubricants with low volatility, high specific heats, and large heats of

vaporization are prefkmd for emissions reduction? It was noted in Section 2.4.3 that rolling

lubricant propemes are different for aluminum and copper. The differences include a higher

vapor pressure, lower boiling point range, and lower heat capacity for the aluminum rolling

lubricant. Each of these may contribute to the observed higher ratio of VOC vapor/mist for

aluminum versus copper rolling mills (see Section 2.4.4).

The lubricant application technique can influence mill emissions by determining the

quantity and physical state of the lubricant. Often, application technique is dictated by the type

of product and product quality.’ For example, spraying the lubricant through a nozzle more

evenly distributes the lubricant, but increases the potential for VOC emissions because the

lubricant is partially atomized in the spraying process. Atomized lubricant is more likely to be

lost as vaporized VOC emissions due to the greater surface area available for evaporization. The

flooding technique, mainly used for high heat generating operations such as foil rolling, increases

the potential for splashing and sump overflow emissions.

The operating temperature of the lubricant is a very important factor in determining

emissions because vapor pressure (hence, rate of lubricant evaporation) is strongly temperature

dependent. As discussed previously, mill parameters determine the required lubricant operating

temperature. Lower oil operating temperatures are desirable for emissions control because the

lubricant is less volatile at lower temperatures.2

2-18

I

~ 2.4.6 Degradation of Rolling Lubricant

After many passes through a rolling mill, the lubricant begins to degrade causing a change

in its original properties. During the rolling process metal h e s are generated which contaminate

the oil and must be removed before further use. A recirculation and filtration system is used for

this purpose. However, after several recycling and frltering steps, the bulk of the oil experiences

a change in physical properties. Additives that were used to enhance base oil properties are

inadvertently fdtered out and must be replenished. In order to recover original lubricant from

the dirty oil, a separate distillation process is required. Since distillation is not conducted at most

nonferrous rolling mills, the dirty oil waste is either burned in the plant or sold as a waste oil.

Other degradation to the rolling lubricant takes place over a period of time. The

continuous high temReratures that rolling oils experience will, after a period of time, reduce the

viscosity (and, therefore, the usefulness) of the oil. Also, contamination occurs from the

hydraulic oils used to lubricant machine parts. These oils are usually heavier than the rolling oils

and over time wil l degrade the properties of the original rolling lubricant. Recovery of the base

roiling oil again requires the distillation step noted previously. .

2.4.7 Current Emissions Controls in the Rolling Industry

At present, very few U.S. rolling establishments employ any type of control device to

reduce vaporized VOC emissions. Capture devices are used in the aluminum industry to some

extent. Most aluminum foil operations utilize some type of capture system to remove lubricant

vapor from the work area. Aluminum sheet and plate operations are typically uncontrolled.*

Some copper rolling facilities use capture systems to collect and reclaim lubricant, however,

industry-wide capture systems are not believed to be prominent'*''

The types of control equipment used by aluminum and copper rolling mills mainly

consists of impactors, centrifuges, or mist eliminators designed to control VOC mist (mostly

considered to be particulate matter greater than 10 microns in diameter) as opposed to VOC

vapor. Each of these devices is quite adept at controlling particulate (most are 90 percent

efficient or better); however, none of these devices are designed to control VOC vapor emissions.

2-19

A number of U.S. mills, especially aluminum foil rolling mills, have, instead of add-on

control devices, implemented a change in rolling lubricant. Lubricants with different emissions

level properties, but with the same or better rolling properties (see discussion Section 3.4) have

been introduced and have proven their applicability and performance. The new rolling oils

typically cost more than previous oils, but with the addition of distillation equipment have proven

themselves to possibly be the most cost-effective approach to lower VOC emissions.

2-20

2.5 REFERENCES

1. Smirnov, V.V. and A.I. Tseiikov. Rolling Mills. Pergamon Press Ltd., Oxford, London. 1965.

2. U.S. Environmental Protection Agency. Volatile Organic Compound Control at Specific Sources in Louisville, KY, and Nashville, TN. EPA-904/9-81-087. Region 4, Atlanta, GA. December 1982.

3. Executive Office of the President. Standard Industrial Classification Manual. Office of Management and Budget, 1987.

4. Teleconference between J. Manion of the Department of Commerce - Nonferrous Metals Division and S. Snow of Alliance Technologies Corporation. December 18, 1991.

5: U.S. Depar&ent of Commerce. 1987 Census of Manufacturers, Industry Series - Nonferrous Metal Mills and Miscellaneous Primary Metal Products. MC87-1-33D. Bureau of the Census. Issued May 1990.

6. Booser, E. Richard, Editor. Handbook of Lubrication - Theory and Practice of Tribology, Volume II. The American Society of Lubrication Engineers. CRC Press, Inc., Boca Raton, FL. 1983.

7. Larke, Eustace C. The Rolling of Strip, Sheet, and Plate. Second Edition. Chapman and Hall, Ltd. 1963.

8. Teleconference between R. Carwile of the Aluminum Association Incorporated and S. Snow of Alliance Technologies Corporation. January 2, 1992.

9. Kumar, Surinder. Overview of a Rolling; Mill from Proceedings of the Workshop on Characterization and Control of Aluminum Cold Rolling Mills. Aluminum Association Incorporated. November 1983.

10. Teleconference between P. Mara of the Aluminum Association Incorporated and S. Snow of Alliance.Technologies Corporation. December 18, 1991.

11. Teleconference between C. Dralle of the Copper and Brass Development Association and S. Snow of Alliance Technologies Corporation. December 17, 1991.

- 12. Avallone, Eugene A. and Theodore Baumeister ID, Editors. Mark's Standard Handbook for Mechanical Engineers. Ninth Edition. McGraw-Hill Book Company, New York, NY. 1986.

2-2 1

13.

14.

15.

16.

17.

18.

19.

20.

21.

Shackelford, James F. Introduction to Materials Science for Engineers. Macmillan Publishing Company, New York, NY. 1985.

Teleconference between M. Roark of Olin Brass Company in East Alton, IL and S. Snow of Alliance Technologies Corporation. January 8, 1992.

Shey, John A. Tribology in Metalworking - Friction, Lubrication and Wear. American Society for Metals, Metals Park, Ohio. 1983.

Kalpakjian, Serope and Elliot S. Nachtman. Lubricants ana' Lubrication in Metalworking Operations. Marcel Dekker, Inc., New York, NY. 1985.

Sandberg, Elina and Rolf Skold. Water-based Aluminum Cold Rolling - ReDort from a Lubricant DeveloDment Promam in Lubrication Engineering. Journal of the American Society of Lubrication Engineers. Volume 41, Number 9. September 1985.

Teleconference between V. Middleton of O h Brass Company in East Alton, IL and S. Snow of Alliahce Technologies Corporation, with . March 16, 1992.

Teleconference between M. Tanchuk of Reynolds Metals Company in Richmond, VA and S. Snow of Alliance Technologies Corporation, with . March 18, 1992.

Barten, Axel E. A New Svstem for Seuaration and Recvcling. of Mineral Oils from Process Fumes in Lubrication Engineering. Journal of the American Society of Lubrication Engineers. Volume 39, Number 12. December 1982.

Trip Report to Olin Brass Corporation, East Alton, IL by Alliance Technologies Corporation. February 10, 1992. See Appendix A.

2-22

CHAPTER 3

VOC EMISSION CONTROL TECHNIQUES

3.1 INTRODUCTION

This chapter contains descriptions of various VOC emission control techniques that may

be applicable to the nonferrous metal rolling industry. Capture systems are briefly discussed in

Section 3.2 while control devices are discussed in Section 3.3. Control devices discussed in h s

chapter include fixed-bed and fluidized-bed adsorbers, thermal and catalytic incinerators, carbon

adsorbers, and oil absorbers. Lubricant substitution as well as process and equipment

modifcations are discussed in Section 3.4 and Section 3.5, respectively. Estimated costs for

sope of these control options are discussed in Chapter 4.

3.2 CAPTURE SYSTEMS FOR NONFERROUS ROLLING MILLS

In the rolling plant, VOC vapors and droplets (mist) are generated from the rolling mill

stand via mechanisms described in Chapter 2. Emissions left uncontrolled can generate high

VOC concentrations in the work area compromising health, safety, and productivity. Control of

these VOC emissions can be achieved by ventilating the manufacturing area to well designed

control equipment. Several*capture devices such as enclosures, hoods, and other devices are

applicable to the rolling mill to remove vapor and liquid VOC from the manufacturing area and

transport them to appropriate control equipment.’

Several factors are important in the design of a good capture system. A primary capture

system criterion is that the system maximize VOC capture at the minimum cost. Optimization

of cost is generally achieved by increasing the degree of closure around the emission area to

minimize capture airflow, because airflow volume is the primary factor influencing control

system cost. However, it is also necessary to consider other issues in designing a practical

capture system.‘

Other considerations in addition to airflow and cost include fire and explosion hazards,

visibility requirements, and maintenance access. To prevent the risk of fire or explosion, the

maximum VOC concentration within capture and control systems should be kept below 25

3- 1

percent of the VOC’s lower explosive limit (LEL). The LEL of a vapor is the lowest

concentration (by volume) in air which will explode, ignite, or burn when there is an ignition

source. Because VOC concentrations are not uniform within the capture system and to ensure

that no large part of the capture system reaches concentrations greater than 25 percent of the

LEL, a good capture system should provide average VOC concentration around 10 percent of the

LEL.

Worker visibility must be maintained so that operators can clearly observe the rolling mill

operations. Also, maintenance and repair of the rolling stand and the coil system requires ready

operator access to the mill by means of openings, movable hoods, or panels.’

A typical rolling mill stand capture system is shown in Figure 3-1. The rolling mill is

enclosed on four sides up to the pass line. Above the pass line, canopy hoods or slotted

perimeter hoods extend over the rolling stand from the mill enclosure to each coil. This

arrangement can be augmented with flexible closures (such as rubber flaps) and air curt&s that

further contain VOC emissions while providing good visibility and ready access. Little published

data exist to indicate how much of the cold rolling lubricant is removed from a typical exhaust

system. However, two industry sources revealed that localized hooding can achieve 70 percent

capture while mill enclosures can attain 90 to 95 percent c a p t u ~ e . ~ ~ Lubricant exhaust system

air volumes for hot and cold rolling mills typically range from 11.8 m3/s (25,000 cfm) to 47.2

m3/s (100,000 c f m ~ . ~

Proper design and maintenance of the control system can potentially reduce lubricant

losses and prevent lubricant entrainment into the exhaust gases. Drains located in the ductwork

should be installed in proper locations and regularly checked for possible obstructions. The

ductwork should also be kept clean of metal scrap and other debris which could lodge itself in

the ductwork and become re-entrained or evaporated by the exhaust gas stream.’

3.3 CONTROL DEVICES FOR NONFERROUS ROLLING MILLS

After entering the capture system, the VOC-laden airstream is directed to a control device

which can either remove or destroy the volatilized lubricant from the airstream. The control

device exit airstream is then exhausted to the atmosphere or recirculated to the plant. Some

devices, such as the carbon adsorber and oil absorber, separate the VOC from the airstream

3-2

I

Mill Housing

Entry Hood i LJ tnput Coil

Plant f loor

--p

Exit Hood

I p- Four-sided I Enclosure I 1

\ I 1

Figure 3-1. Typical rolling mill stand capture system.

3-3

without destroying it, allowing the VOC to be recovered or reused. In contrast, other control

devices, such as thermal or catalytic incinerators, destroy the VOC. The following sections

describe devices which may be applicable for use in the rolling industry to remove VOC vapors

and mist from the air. Specifically, Section 3.3.1 discusses carbon adsorption, Section 3.3.2

discusses absorption, and Section 3.3.3 discusses incineration.

3.3.1 Carbon Adsorption

Adsorption is a non-chemical process that bonds gaseous molecules to other surfaces by

means of Van der Waals forces. In the carbon adsorption process, VOC emission streams pass

through a bed of activated carbon in which the VOC molecules are captured on the porous carbon

surfaces. The adsorphve capacity of the carbon bed tends to increase with the parameters such

as gas phase VOC concentration, molecular weight, diffusivity, polarity, and boiling point of the

VOC.6 After the working VOC capacity of the carbon is reached, the VOC can be desorbed from

the carbon and collected for reuse.

Desorption of VOC from the used carbon bed is typically achieved by passing low-

pressure steam through the bed.' In this regeneration cycle, heat from steam forces the VOC to

desorb from the carbon and become entrained in the steam. After the carbon bed has been

sufficiently cleared of VOC, it is cooled and replaced on line with the emission stream.

Meanwhile, the VOC-laden steam is condensed, and the VOC separated from the water by

decanting or, if necessary, by distillation. If the VOC is not recovered for reuse or reprocessing,

it may be incinerated.' Some systems use heating units and nitrogen gas rather than steam to

desorb the VOC from the carbon bed.

Two commonly used adsorption devices are the futed-bed adsorber and the fluidized-bed

adsorber. Each of these is discussed separately in the following paragraphs.

In a continually operating fixed-bed system, the VOC emission stream is passed through

two or more non-mobile carbon beds. In a two-bedsystem, one bed is on-line with the emission

stream while the other bed is either being regenerated or on standby. When the first bed reaches

its working VOC capacity, the emission stream is redirected to the second bed, and the first bed

is regenerated. While two beds are common, three or more beds can be used in a variety of

3-4

configurations, with more than one bed on-line at any given time? The carbon in a fixed-bed

system can typically be used for five years before replacement is necessary.6

The fluidized-bed adsorber system contains one or more beds of loose, beaded activated

carbon. The VOC emission stream is directed upward through the beds where the VOC is

adsorbed onto the carbon. The flow of the emission stream st i rs the carbon beads causing it to

"fluidize" and flow within the adsorber. The VOC-cleaned air exiting the adsorber is passed

through a dust collector (to remove any remaining carbonaceous particles) then released into the

atmosphere? Regenerated carbon is continually metered into the bed whde VOC-laden carbon

is removed for regeneration? The beaded carbon may be used and regenerated many times

before replacement becomes necessary. Attrition for one brand of adsorbent applicable to

aluminum rolling is reported to be less than 2 percent per year."

Fluidized-bed,adsorbers can capture more VOC than a fixed-bed adsorber with a given

quantity of carbon because the fluidized bed mixes newly regenerated carbon and VOC more

thoroughly, and because the system continually replaces used carbon with regenerated carbon.

This increased VOC-capacity reduces costs for steam regeneration.

Carbon adsorbers are commonly used for air pollution control and/or solvent recovery

from dilute (less than 10,OOO ppmv) streams of VOC in air. Adsorption provides a very low

outlet VOC concentration as well as the opportunity to recover and reuse the VOC. Collection

efficiencies can range from 95 to 99 percent for well-operated systems. Packaged systems are

available with flow rate capacities beyond 170,000 m3/h (lO0,OOO ~ c f m ) . ~

The principal advantage of carbon adsorption is that it is very cost effective with

relatively low concentrations of VOC. In an adsorber, VOC recovery offsets operation costs, and

operation of the adsorber is relatively simple for both continuous and intermittent use. It is

essentially a dry process which provides an inherent safeguard against liquid carryover after the

vapor removal stage.

Carbon adsorbers exhibit some disadvantages with certain types of VOCs such as those

which are difficult to strip from carbon or those which are miscible with water (such as

emulsions). If the collected VOC is miscible with water, additional distillation measures are

necessary to recover the VOC. If steam-stripping is conducted with chlorinated hydrocarbons,

corrosion and wastewater treatment problems may occur." Also, carbon adsorption is relatively

sensitive to emission stream humidity and temperature. Dehumidification is necessary if the

3-5

emission stream has a high relative humidity (greater than 50 percent) and cooling may be

required if the emission stream temperature exceeds 49 to 54OC (120 to 130°F).9 Other disadvantages include frequent carbon changes (although less so for fluidized-bed

adsorption) and retrofit equipment installation. Retrofit equipment includes hooding, ductwork,

and the control device itself as well as its support structure.'2 Only one known U.S. facility has

installed a carbon adsorber on a new rolling mill. Other unknowns for rolling mill applicability

include FDA approval (aluminum industry only) for reuse of recovered oil" and amount of

deterioration of the oil (Le., loss of additives, contamination by desorbant) after desorption.

3.3.2 Absorption (Scrubbing)

In the absorption process, VOC is removed from the emission stream by absorption in a

liquid solvent such as a high molecular weight oil. Spray towers, venturi scrubbers, or other

methods are used to bring the absorbent into contact with the emission stream. After the VOC

dissolves into the solvent the cleaned gas is exhausted to the atmosphere and fractional . distillation or some other method is used to recover the VOC from the ab~orbent.7.'~

Absorption is applicable to many industrial processes, including nonferrous metal rolling

mill^.'^"^ It is most efficient when the VOC is soluble in the absorbent, and when the absorbent

boiling point is significantly higher than the VOC to be absorbed. Absorbers have been shown

to remove at least 86 percent and even greater than 99 percent of the waste stream VOC for

various species .**I1

Oil absorbers can be used with a wide variety of organic compounds without many of the

problems associated with other VOC control devices such as the carbon adsorber or incinerator.

A closed-loop system has been developed that demonstrates no equipment deterioration with

extended use and operates without generating steam, corrosion, or wastewater."

One source identified oil absorption as perhaps the most applicable control device for

rolling mill emissions? Despite its advantages, however, most absorption systems are not cost

effective with very low inlet VOC concentrations." Typically, absorption systems are applicable

for VOC concentrations from 250 to 10,OOO ppmv? A major disadvantage to the oil absorption

system is the deterioration in recovered lubricant because absorption reduces the amount of

lubricant additives, therefore oil reformulation must be performed adding another step to the

3-6

process. Another difficulty (for the aluminum rolling industry) could be gaining FDA approval

to reuse the recycled oil. Finally, severe retrofit problems arise when considering an oil

absorption system for VOC control. Sufficient size and space areas must be located for hooding,

ductwork, control device and support str~cture.'~ Some of these units may be taller (up to 60

feet) than the rolling plant they were designed to ~ontrol.'~

These restrictions make the oil absorber a less-frequently used option for VOC control

in the rolling industry. In fact, no installations are known in the United States and only one is

used in For most industrial processes, the waste stream VOC concentrations are

generally low, making absorption less desirable than adsorption or incineration unless the

absorbent is easily regenerated or the solution (lubricant) can be immediately returned to the

process stream.7

1

33.3 Incineration

Incineration remove VOC from an emission stream by combustion, converting the VOC

into carbon dioxide, water vapor, and small quantities of other compounds. The VOC-laden .

emission stream enters the incinerator chamber where the VOC is ignited, sometimes with the

assistance of a catalyst. Incinerator performance is a function of the waste gas heating value,

inert content, waste gas water content, and the amount of excess combustion air? Other design

variables include degree of mixing, residence time, and the type of auxiliary burning used.

In contrast to adsorbers and absorbers, incinerators do not recover the VOC for reuse;

however, valuable heat is generated during the combustion reaction which may be recovered for

use elsewhere in the plant. The two types of incinerators in common industrial use are the

thermal incinerator and the catalytic incinerator. Each of these are discussed in the following

paragraphs.

Thermal incinerators pass the emission stream through a combustion chamber where the

VOC are burned at temperatures typically ranging from 700 to 1,300OC (1,300 to 2,37OoF)?

Initially, burning is begun with the assistance of a natural gas flame or similar heat source. If

'the VOC in the emission stream have sufficient heating value and concentration, ignition

temperatures can be sustained by the combustion of the VOC, and the auxiliary heat source can

be turned off. If the ignition temperature cannot be maintained by combustion of the waste

3-7

stream alone, the auxiliary heat source must remain on. Auxiliary heat can be provided by fuels

such as natural gas, and from recovery of heat released during combustion. Waste gases from

thermal incinerators are usually vented to the atmosphere.

Catalytic incinerators are similar to thermal incinerators in that they eliminate VOC from

the waste stream via combustion. The distinguishing feature of a catalytic incinerator is the

presence of a catalyst (such as platinum or copper oxide) that allows VOC combustion to take

place at a lower ignition temperature than normal?' By allowing the combustion reaction to take

place at lower temperatures than required for a thermal incinerator, less preheating of the

emission stream from auxiliary heat is necessary, and significant fuel savings can be achieved.

In the catalytic incinerator, the emission stream is preheated to approximately 320°C

(600°F) by recovered incinerator heat or by auxiliary burners.' The preheated emission stream

is.passed through the, catalyst bed where combustion takes place on the activated catalytic

surface. The catalytic incinerators are operated from 320 to 650°C (600 to l,200"F), significantly

lower than operating temperatures for thermal incinerators. Higher temperatures can shorten the

life of the catalytic bed. Properly operated catalytic converters can be satisfactorily operated for

3 to 5 years before replacement of the catalyst is necessary?

Thermal and catalytic incineration are both widely used to control continuous, dilute VOC

emission streams. Both types of incinerators can typically achieve VOC control efficiencies of

approximately 98 percent7 For safety considerations, VOC concentrations within the incinerator

are usually limited to 25 percent of the VOC's lower explosive limit. If the VOC concentration

is higher in the waste gas, dilution air may be req~ired.~ Packaged, single-unit thermal and

catalytic incinerators are available to control emission streams with flow rates up to about

170,000 m3/h (l00,OOO ~ c f m ) . ~ . ~

Relatively lower energy costs make the catalytic incinerator an important option for

control of VOC from eniission streams; however, the catalytic incinerator cannot be utilized in

as many applications as the thermal incinerator. Catalytic materials can be quickly degraded by

many elements or compounds present in rolling mill emissions such as metal fines (particulates).

Many of these materials are burned without difficulty in thermal incinerators.

Thermal and catalytic incinerators are often well-suited for control of VOC from rolling

mill emission streams. Heat recovery is readily attained with both thermal and catalytic

incinerators, enhancing the economics of using an incinerator rather than other VOC control

3-8

devices. Thermal incinerators remove particulates and other organics in addition to VOCs, thus

enhancing their utility.'

However, there also exist some disadvantages to using incinerators. First, incinerators

destroy the VOC rather than recovering them; in some cases (especially for petroleum based

lubricants), the energy benefit may not be as great as the lost value of the VOC. One source

indicated that thermal or catalytic incinerators m technically but not economically feasible for

aluminum foil rolling emission controi.'6

Incinerators may not be practical choices for VOC removal if certain types of VOCs or

other materials are burned. Incineration of VOC emission streams that contain halogens or sulfur

can produce acidic compounds such as HC1 or SO,; these streams are likely to require additional

equipment, such as a scrubber, for removal of the acid components, greatly adding to the cost

of the voc control system.' Catalytic incinerators are very sensitive to materials in the emission

stream that can reduce the effectiveness of the catalyst. Phosphorous, lead, sulfur, and halogens

can poison typical catalysts and severely affect their performance? If it is necessary to use

catalytic incineration to control waste streams containing these materials, special catalysts or

other measures must be employed. Liquid or solid particles that deposit on the catalyst and form

a coating also reduce the catalyst's usefulness by preventing contact between the catalyst and the

VOC.~*~ For safety reasons, both thermal and catalytic incinerators may require large amounts of

dilution air to reduce the VOC concentration in the emission stream below 25 percent of the

LEL. Heating the dilution air to the ignition point of the VOC may be prohibitively expensive,

particularly if a waste gas contains entrained water droplets which must be vaporized and raised

to combustion chamber temperature. Finally, retrofit installation will require adequate space and

support strength to house the necessary equipment.

3.4 LUBRICANT SUBSTITUTION (SOURCE REDUCTION)

Lubricant substitution is not considered a VOC control technique, but more of a pollution

prevention or source reduction technique. Typically, new equipment or equipment modifications

are not required with a change of rolling lubricant, however, some process parameters, such as

mill speed, gauge reduction per pass, etc., will most likely be altered to accommodate the new

3-9

lubricant’s physical properties. This section briefly discusses the physical and chemical

properties associated with different types of lubricants and relates those to current industry

experience with the various lubricants. The applicability of lubricant substitution to the rolling

process and as an emissions control technique is also explored.

Note that most of the information contained here pertains to the aluminum foil rolling

industry since it is within this industry that the latest developments in lubricant substitution to

reduce VOC emissions have occurred. Also, since water based emulsions are assumed to

represent a small amount of total VOC emissions from the aluminum foil rolling industry, only

petroleum based lubricants are considered to be candidates for lubricant substitution.

This section is organized into four subsections that include a discussion of emission

reduction mechanisms for lubricant substitution (Section 3.4.1), a discussion of the applicability

of.lubricant substitutip to the rolling process (Section 3.4.2), a discussion of the applicability

of lubricant substitution as an emissions control method (Section 3.4.3), and a summary of the

advantages and disadvantages associated with lubricant substitution performed in the aluminum

foil rolling industry (Section 3.4.4).

3.4.1 Emission Reduction Mechanisms of Lubricant Substitution

Differences in the physical properties of lubricants are the major reason that, theoretically,

a significant amount of VOC emissions can be avoided. The major properties associated with

emission reduction are vapor pressure, specific heat, and heat of vaporization (see Section 2.4.3).

A lubricant with higher vapor pressure implies a shorter chain length of hydrocarbons and thus

a lower molecular weight. This allows higher lubricant evaporation during the rolling process

when compared to a lubricant with lower vapor pressure (Le., longer chain length and higher

molecular weight). For .this discussion, the term heavy oil refers to those oils with a relatively

lower vapor pressure (less than 1 mmHg) while thin oils refer to a relatively higher vapor

pressure (greater than 1 mmHg). As discussed previously, heat removal capacity is important

in reducing emissions because a higher capacity implies that more heat is necessary to vaporize

the lubricant. For this reason, for reducing emissions, a heavy oil with high specific heat and

heat of vaporization properties would be preferred to a thinner oil. These properties have resulted

3-10

in reduced vapor generation and lower material costs because more of the lubricant can be

captured and recycled.” I

The lubricant oil operating temperature is another very important mechanism affecting

emissions because the vapor pressure of the lubricant, and therefore the rate of lubricant

evaporation, is highly temperature dependent” Low operating temperatures are desirable from

the standpoint of emissions control due to the fact that the lubricant is less volatile at lower

temperatures. Many manufacturers of cold rolled aluminum have successfully experimented with

reducing oil operating temperatures to the lowest possible temperature that product quality

considerations will allow. 1217~18 Lubricant application temperature is typically the same for most

nonferrous rolling operations averaging around 38 to 49OC (100 to 120°F) although it may be somewhat higher for aluminum operation^.'^

New technologies are emerging that use a water-based rolling oil for aluminum rolling

operations. Several advantages could be realized with water-based lubricants including better

heat removal, lower coolant cost, lower emissions, better mill safety, and FDA compliance.

However, there are major disadvantages that render current water-based technology unfeasible

for aluminum rolling operations. These include sheet water stain and retrofit equipment

requirements for the new water-based systems. These problems are being addressed and there

are continuing efforts to find a suitable substitute for the current petroleum-based lubricants.20

’

3.4.2 Applicability of Lubricant Substitution to Rolling Process

The aluminum foil rolling industry has traditionally used thinner oils than other nonferrous

rolling industries because of end-product concems.” During the 1980’s’ several facilities

experimented with lubricant changeover from the traditional kerosene (a mixture of C,, - C,,

hydrocarbons) lubricant to normal or linear paraffin oils (Cll - C,,).17 Linear paraffms are

components of the kerosene fraction of crude oils and are separated from kerosene in pure form

by molecular-sieve ab~orption.“’~ The paraffins were evaluated based on physical properties and

other parameters pertinent to the aluminum foil industry. These additional parameters include

surface finish quality, mill production rate, FDA approval, and fla”ability.12

At least three separate studies indicate that the linear paraffin oil produced an equivalent

or better surface finish quality than the original kerosene lubricant.’218z1 This was expected since

3-11

the linear paraffin has a lower viscosity than kerosene and surface finish quality generally

increases with lower vis~osity.~’ The linear paraffins also demonstrated better viscosity stability

than kerosene due to the relatively n m o w boiling ranges of the ~araffins.2~ Long-term, full-scale

experiments indicated that production rates were not adversely affected and actually increased

with lubricant changeover to linear paraffms.’*”’

Linear paraffms also comply with FDA regulations that are required of aluminum

lubricants.12 Other nonferrous metal rolling lubricants are not typically required to meet FDA

~tanda rds . ”~ Flammability is normally measured by the lubricant flash point and, as data in

Table 2-2 indicate, linear paraffins exhibit a higher flash point than kerosene, ideally providing

an extra margin of safety against fire hazards in the rolling plant“”

As stated in Chapter 2, different mills require different lubricant properties based on

several operating parFeters. Also, different metals require different lubricant properties based

on the reaction of the lubricant to the metal which they are applied. Additionally, each stage in

the production of a particular metal-finished product may require inherently different lubricant

properties. In some cases, these separate requirements can be met by the addition of various

. additive packages. However, in the case of aluminum foil production, the initial stages where

rolling thicknesses are high (aluminum sheet) require a heavier oil relative to the final stages

where rolling thicknesses are small (aluminum foil)? The reasons for this are surface fmish,

production rates, metal reaction to oil, and FDA approval.”

Most other types of nonferrous metal rolling operations typically use lubricants with

similar properties. Copper and other nonferrous metal lubricants have nearly the same vapor

pressure (less than 0.1 millimeters of mercury)” and around the same viscosity. Differences may

occur in the additive packages used with each metal lubricant or the application method of the

lubricant.

In order for a facility to implement lubricant substitution, sufficient research and

development (R&D) must occur to ensure that the new lubricant will not interfere with

production. Bench-scale, pilot-scale, and full-scale tests are normally conducted to determine the

performance requirements of new oils. For the aluminum foil industry, linear paraffms have

undergone extensive full-scale tests and, on the basis of lubricant property assessment, there is

no apparent technical reason to believe that linear paraffins cannot be used as a lubricant for most

cold rolling of aluminum foil.” If substitutes are to be found for other nonferrous metals, they

i

3-12

must also undergo rigorous R&D to determine their applicability. A few other nonferrous metal

rolling operations are currently evaluating options not to change lubricants, but to recover and

reuse the oil they currently employ to roll.

3.43 Applicability of Lubricant Substitution as a Control Method

No data exist to detennine an exact level of VOC emissions reduction from lubricant

substitution in nonferrous rolling mills. All plants and mills are different and many variables

must be considered in order to determine emissions reduction. However, a few case studies

exemplify the theoretical amount of rolling oil usage reduction possible from aluminum foil

rolling mills that switch from traditional kerosene to linear paraffins. Based on a direct

comparison of lubricant physical properties, a potential emissions reduction of 10 to 30 percent

is' possible with changeover to linear paraffin This potential, however, does not fully

account for the observed 63 percent reduction in oil usage (based on mass consumption) noted

at one aluminum rolling facility."

During 1980, Kaiser Aluminum and Chemical Corporation Permanente's Cupertino,

California plant underwent a full-scale experiment involving the substitution of linear paraffin

for kerosene. After six months of operation, total rolling oil usage had declined an average of

63 percent with the linear paraffin. After this experiment, Exxon Corporation began, in 1982,

marketing linear paraffins as aluminum rolling oils. Since that time other mills report switching

to the new oil and have experienced usage declines by as much as 50 percent. Kaiser also

experienced other advantages from lubricant changeover including more stable oil viscosity, fewer

mill fires, higher quality aluminum foil, lower rolling oil odor, and a savings of major capital

expenditures (for add-on VOC control equipment). There were disadvantages observed that

included a higher cost of the aluminum rolling oil, a slight change in annealing practices, and the

inconvenience of no local aluminum rolling oil supplier at that time ( 1980).21

A separate study was performed at the ARCO Aluminum Louisville Rolling Plant in June

and July of 1982. ARCO experienced a lubricant use reduction of 58.5 percent and an organic

-vapor reduction of 21 percent on one mill with a linear paraffin test oil. It was noted that the

quality of rolled material was not appreciably different than that produced with the original

kerosene lubricant. A larger scale study was performed in early 1983 in which ten rolling mills

3-13

in the plant were subjected to the new rolling oil. Results were not as favorable with only a 30

percent reduction in lubricant use for the entire line during the trial run. Therefore, ARC0

determined that it was feasible to use the new rolling oil on only about 60 percent of the mills

located at the Louisville facility.= This indicates that, as stated previously, linear paraffin oil

may not be applicable to all aluminum foil rolling mills.

Rolling mill VOC emissions are difficult to measure with accuracy due to the many

variables that can impact the results. Observed emissions at one given time may vary greatly

between emissions observed at a separate time on the same mill.'* However, each of these case

studies show that lubricant substitution can affect not only the lubricant emissions but the amount

of usage as well. The reason is that the inherent lower volatility of linear paraffins reduces the

evaporative losses from rolling operations.

3.4.4 Summary of Lubricant Substitution Advantages and Disadvantages

As noted from the case studies presented here, there are several advantages and

disadvantages that have been recognized with the implementation of lubricant substitution in the

aluminum rolling industry. No such case studies or literature were available for other nonferrous

metal rolling operations. Note that these advantages and disadvantages are general in nature and

may not apply to a specific mill which implements lubricant substitution.

I

Advantages and disadvantages observed from lubricant substitution in aluminum f c 4

rolling mills are listed given in Table 3-1. References for each item are given in the table. Note

that an exact relationship between lubricant usage and emissions reductions has not been

developed, therefore the amount of VOC emissions reduction potential is unknown. Also, the

level of R&D required will vary from mill to mill and cannot be estimated to any accuracy.

Table 3-1 indicates that there are more advantages than disadvantages realized from substitution

of linear paraffm for kerosene in the aluminum foil rolling industry.

3.5 PROCESS AND EQUIPMENT MODIFICATIONS

Other pollution prevention techniques besides lubricant substitution include various

process and equipment modifications. These techniques should be applicable to the entire

3- 14

TABLE 3-1. SUMMARY OF ADVANTAGES AND DISADVANTAGES OF LUBRICANT SUBSTITUTION EXPERIENCE IN THE ALUMINUM F O E ROLLING INDUSTRY

Advantages Disadvantages

Reduction in rolling oil usage (up to 63 percent observed)1ZZ1

Presumably a reduction in VOC vapor emissions"

No major process changes required2'

Capital cost savings (no add-on control devices required)1221

Lower rolling oil od03'

i

Lubricant viscosity remained more stable than kerosene1821

Equal or better quality foil product (less staining, brighter surface finish) 121821

Lower level of additives required'8v2'

121821 Higher mill speeds achieved

Simpler annealing process2'

Increased gauge reduction per pass2'

Cleaner working area21

Greater ease of lubricant filtering"

Fewer mill fires observed21

FDA appr~val"'~

Higher cost of the linear paraffin1821

A broken matte surface observed under some conditions1s

Greater dragout than kerosene/mineral seal Oil'

Potential skin irritation (good personal hygiene practices required)'8*u

R&D required to determine applicability of new rolling lu bric an t I2

Linear p d i n cannot be re-sold as a waste fuel oil like ker~sene'~' '

Additional recirculation and recycling equipment may be needed to offset higher cost of new rolling OW No published data for reduction of VOC vapors (unknown control effectiveness)

3-15

nonferrous rolling industry although most information sources were for the aluminum rolling

industry. Process modifications relate to mill and lubricant operating parameters (discussed in

Section 2.4.6). Equipment modifications include the addition of better capture devices, filtration

equipment, and recirculatiodrecycling equipment. Each type of modification can affect the level

of emissions, however, no currently published data cite the magnitude of the overall effect on

VOC emissions.

3.5.1 Process Modifications for Potential VOC Emission Reduction

Many operating parameters can impact the amount of VOC emitted from any given rolling

mill. They include mill speed, gauge reduction per pass, hood face velocity, control system

design and maintenyce, lubricant application technique, rate of lubricant application, and

lubricant operating temperature. Each of these parameters can be modified with the potential for

reducing rolling mill emissions. This section discusses each of these parameters.

The first two parameters listed, mill speed and gauge reduction per pass, affect the

quantity of heat generated at the work rolls. Higher mill speeds and larger gauge reductions

generate larger amounts of heat which require larger volumes of oil to provide adequate

lubrication and cooling. Larger volumes of oil provide the potential for higher lubricant

emission^.'^ Modifcation to these operating parameters, however, may result in reduced

production. It is unclear as to the level of decreased production due to changes in mill speed or

gauge reduction, and whether it would prove economically feasible to reduce VOC emissions by

this route.

.

Another potential affect on VOC emissions is the face velocity of the capture hood.

Higher gas velocities at the hood would be expected to improve convective mass transfer

conditions at the oil surface and to increase the degree of oil droplet entrainment in the exhaust

gas stream.17 Both of these phenomena would tend to increase the apparent amount of VOC

emissions. Thus capture hood face velocities should be adjusted to minimize each of these

phenomena while at the same time ensuring the sufficient removal of mist and vapor

concentrations in the workp~ace.'~

The method and rate of lubricant application impact the quantity and physical state of the

oil which, in turn, affect the level of emissions. Spraying the lubricant through a nozzle increases

3-16

I '

the potential for VOC vapor because the oil is partially atomized in the process. Atomized oil

has better potential to become vaporized and emitted because of the increased surface area

available for evaporation." Flood and drip techniques may reduce the potential for VOC vapor

emissions, however, they cannot .be as uniformly applied to the metal and work rolls as spraying.

Any modification of application technique is dictated by the required product quality, mill speed,

gauge reduction, and technical feasibility. The lubricant application rate should be reduced to

that required to provide sufficient heat removal and lubrication with as little excess as possible.

Higher application rates are generally needed at higher mill production rates (mill speed and

gauge reduction) because more heat is generated and must be removed.17

The impact of operating temperature on the level of emissions was previously discussed

in Section 3.4.1 of this report and therefore will not be further discussed here.

As stated in Section 3.4.2, some amount of R&D effort will be required to implement

many of the changes to the rolling process in order to reduce emissions. Sufficient bench- and

full-scale testing wil l have to be performed to determine which process changes are feasible and

in what combination to implement them.

1

3.5.2 Equipment Modifications for Potential VOC Emission Reduction

Figure 2-2, presented in Chapter 2, illustrates the basic elements of a lubricant recycling

system. The lubricant flow is cooled after application by plate or tube heat exchangers, and then

filtered through wire mesh filters andor active earth filters before being recycled. The purpose

of filtration is to remove metal fines from the oil that may produce a rough product finish. The

extent to which the lubricant can be recycled depends on the mill temperature, the chemical

composition of base oil and additives, the effectiveness of the filtration system, and the type of

metal rolling taking p1ace.l2

An efficient recirculation system will recover lubricant from the sump, clean out metal

fmes and other impurities, and return the lubricant to the mill for reuse.z2 Some rolling facilities

have installed an intricate lubricant reclamation system, the benefits of which are believed to far

exceed the costs. The benefits include nearly unlimited reuse of lubricant, reduced waste oil

generation, and lower waste oil disposal ~ 0 s t s . l ~ The required equipment includes efficient

filtration systems to filter, cool, and recirculate the oil back to the mills. A distillation unit

3- 17

provides long life for the lubricant by recoverhg usable oil from the waste oil generated in the

filtering system. This oil recovery somewhat offsets the additional cost of the paraffin and the

lost income from the sale of used kerosene. The linear paraffm cannot be re-sold as a waste fuel

oil, thus oil recovery is an economically feasible solution. In addition, the distillation system

reduces off-site disposal costs associated with waste oil. The entire circulation system requires

the addition of collectors, filters, cooling units, oil tanks, and a distillation unit as well as the

auxiliary equipment associated with each. Other considerations must be made for retrofit

construction equipment (Le., supports and struct~re). '~

3-18

3.6

1.

2.

3.

4.

5.

6.

7.

8.

9.

10.

11.

REFERENCES

Roos, R.A., G.P. Fenton, and R.W. Perryman. "Containment of Fumes and Vapors Generated in the Aluminum Rolling Process" in Lubrication Engineering, Volume 40., No. 10. pp. 621-626. American Society of Lubrication Engineers. October 1984.

Teleconference between M. Tanchuk of Reynolds Metals Company in Richmond, VA and S. Snow of Alliance Technologies Corporation. March 18, 1992.

Teleconference between R. Carwile of the Aluminum Association, Inc., Washington, D.C. and S . Snow of Alliance Technologies Corporation. January 2, 1992.

Roos, R.A. "Control of Emissions Generated by Hot and Cold Rolling Operations in the Aluminum Industry" in Lubrication Engineering, Volume 38, No. 5., pp. 288-294. American Society of Lubrication Engineers. May 1982.

McTaggart, ?$arcella. "Overview of Rolling Mill Emissions" in Proceedings of the Workshop on Characterization and Control of Aluminum Cold Rolling Mill Emissions, November 16-17, 1983. Clarksville, IN. The Aluminum Association, Inc.

U.S. Environmental Protection Agency. OAQPS Control Cosr Manual. EPA-45013-90- 006. Fourth Edition. Office of Air Quality Planning and Standards, Research Triangle Park, NC. January 1990.

U.S. Environmental Protection Agency. Control Techniques for Volatile Organic Compound Emissions from Stationary Sources. EPA-45013-85-008. Third Edition. Office of Air and Radiation and the Office of Air Quality Planning and Standards, Research Triangle Park, NC. 1986.

Radanof, R.M. "VOC Incineration and Heat Recovery-Systems and Economicstt in Third Conference on Advanced Pollution Control for the Metal Finishing Industry. EPA-60012- 8 1-028. U.S. Environmental Protection Agency, Industrial Environmental Research Laboratory, Cincinnati, OH. February 1981.

U.S. Environmental Protection Agency. Handbook: Control Technologies for Hazardous Air Pollutants. EPA-62516-86-0 14. Air and Energy Engineering Research Laboratory, Research Triangle Park, NC. September 1986.

Heim, C.J. "Volatile Organic Emission Control in the Aluminum Industry Using Fluidized Bed Carbon Adsorption" in Proceedings of the Workshop on Characterization and Control of Aluminum Cold Rolling Mill Emissions, November 16-17, 1983. Clarksville, IN. The Aluminum Association, Inc.

Ehrler, A.J. "Closed-Loop Absorption for Solvent Recovery" in Metal Finishing Volume 85, No. 11. pp. 53-56. November 1987.

3- 19

I

12.

13.

14.

15.

16.

17.

18.

19.

20.

21.

22.

Reynolds Metals Company, Richmond Foil Plant in Richmond, Virginia. Rolling Mill Emissions Reasonably Available Control Technology (RACT) Demonstration. Prepared by Reynolds Metals Company, September 30, 1987.

Barten, A.E. "A New System for Separation and Recycling of Mineral O i l s from Process Fumes" in Lubricurion Engineering, Volume 38, No. 12. pp. 754-757. American Society of Lubrication Engineers. December 1982.

Wei, M.W., et ul. "Development of An Absorption Unit To Reduce Emission from Aluminum Cold Rolling Operations" for presentation at the 81st Annual Meeting of APCA, Dallas, Texas, June 19-24, 1988. Air Pollution Control Association.

Trip Report to Reynolds Metals Company: Flexible Packaging Division, Richmond, VA by Alliance Technologies Corporation. February 19, 1992. See Appendix A.

Burkhard, Kurt and Uwe Troll. "Experience with the Achenbach Axpure System to Control Rolling Oil Vapor and Mist" in Proceedings of the Workshop on Churacrerization and Control of Aluminum Cold Rolling Mill Emissions, November 16-17, 1983. Clarksville, IN. The Aluminum Association, Inc.

U.S. Environmental Protection Agency. Volatile Organic Compound Control at Specific Sources in Louisville, KY, and Nashville, TN. EPA-904/9-81-087. Region 4, Atlanta, GA. December 1982.

Martin, Roy. "Linear Paraffin Experience - Reynolds Flexible Packaging Division" in Proceedings of the Workshop on Characterization and Control of Aluminum Cold Rolling Mill Emissions, November 16- 17, 1983. Clarksville, IN. The Aluminum Association, Inc.

Teleconference between V. Middleton of O h Brass Company in East Alton, IL and S. Snow of Alliance Technologies Corporation. March 16, 1992.

Fayer, M.C. "Development of water based lubricants for cold rolling aluminum" in Proceedings of the international conference on Advances in Cold Rolling Technology, September 17-19, 1985. London, England. The Institute of Metals in conjunction with The Institute of Measurement and Control.

Landry, W.J. "Use of Normal Paraffins in Cold Rolling Aluminum" in Proceedings of the Workshop on Characterization and Control of Aluminum Cold Rolling Mill Emissions, November 16-17, 1983. Clarksville, IN. The Aluminum Association, Inc.

Trip Report to O h Brass Corporation, East Alton, IL by Alliance Technologies Corporation. February 10, 1992. See Appendix A.

3-20

23. Chapman, Kurt M. "Trial Use of a Linear Paraffin Rolling Coolant at the A R C 0 Aluminum Louisville Rolling Mill" in Proceedings of the Workshop on Characterization and Control of Aluminum Cold Rolling Mill Emissions, November 16-17, 1983. Clarksville, IN. The Aluminum Association, Inc.

3-21

I -

CHAPTER 4

CONTROL COST ANALYSIS

4.1 INTRODUCTION

This chapter contains estimated costs associated with VOC control techniques for

nonferrous metal rolling mills. Each VOC reduction method described in Chapter 3 is costed out

for a typical nonferrous rolling mill configuration. Section 4.2 presents the capital and annual

costs associated with VOC add-on control devices. Section 4.3 estimates the annual costs for

implementing lubricant substitution in a typical aluminum foil rolling mill. (Available literature

indicate that aluminum foil is the only nonferrous rolling industry to implement a lubricant

substitution program to reduce VOC emissions.)

4.2 VOC ADD-ON CONTROL DEVICES

Elements of a typical rolling mill and general cost parameters used to develop annual cost

estimates are given in Table 4-1. An exhaust flow rate of 20,000 acfm for a single mill was

chosen based on published information and review of facility operating permits. An average

VOC concenmtion of 80 ppmv (vapor) was taken from Reference 1. It is noteworthy to mention

that although the control equipment costs developed in this section are for one mdl, facilities may

prefer to install larger units to control emissions from two or more mills at one time. The

following sections present capital and annual costs for the installation and operation of carbon

adsorbers (Section 4.2. l), oil absorbers (Section 4.2.2), thermal incinerators (Section 4.2.3), and

catalytic incinerators (Section 4.2.4). These costs do not include any downtime costs that may

be required for installation of equipment on a specific rolling mill. Lost production in the short-

term would certainly increase the capital costs associated with add-on control devices. All costs

presented here were derived from available literature and EPA cost manuals as referenced in each

subsection.

4- 1

TABLE 4-1. GENERAL PARAMETERS AND COST FACTORS FOR ESTIMATING COSTS FOR ADD-ON CONTROL DEVICES

Parameter or Costs Specified Value ~

Exhaust flow rate

VOC concentration

Utilities

Electricity

Cooling water

Natural gas

Operating labor (OL)

Supervision labor (SL)

Maintenance labor (ML)

Maintenance materials (MM)

Overhead

20,000 acfm

80 ppmv

$O.O6kWh

$0.20/1,000 gal

$3.30/1,000 f?

$13.12/hr

15% of operating labor

$14.50/hr

100% of maintenance labor

60% of OL, SL, ML, and MM

Administration costs

Adsorption and absorption

Thermal and catalytic incineration

4% of total capital investment

2% of total capital investment

0.1628 (Based on equipment life of 10 years and interest rate of 10%)

Capital recovery factor

Operating hours 8,500Iyr

4-2

4.2.1 Carbon Adsorption

Costs for carbon adsorbers were derived from an EPA document that pertained specifically

to the aluminum foil industry.' The costs were developed for one rolling mill configuration (see

Table 4-1). Table 4-2 lists the assumed equipment parameters used to develop the capital and

annual costs. Table 4-3 contains annual costs which were updated to February 1992 dollars by

the use of equipment cost indices in Chemical Engineering? The table shows that direct annual

costs amount to $44,700, indirect annual costs sum to $640,600, and total annual costs equal

$685,300. Note that the highest cost impact is associated with capital recovery, which is a

function of total capital investment. This indicates that high initial equipment costs are

associated with carbon adsorption as a control option.

1

4.2.2 Absorption (Scrubbing)

Costs for oil absorption control were also derived from the document that contained

carbon adsorption costs and, as before, were developed for one rolling mill configuration.' Table

4-4 gives the equipment parameters used to develop annual costs of absorption. Table 4-5

presents the annual costs which were updated to February 1992 dollars by the use of equipment

cost indices in Chemical Engineering.2 Table 4-5 shows that direct costs amount to $120,500,

indirect costs sum to $659,100, and total annual costs equal $779,600. As with for carbon

adsorption, the highest cost impact is associated with capital recovery (i.e., capital investment).

.

4.2.3 Thermal Incineration

Costs for thermal incineration control were derived from published EPA documents that

provide generic estimating procedures for costing add-on air pollution control equipment for

industry in gene1al.3.~ Table 4-6 lists the equipment parameters used to derive annual costs for

thermal and catalytic incineration. Table 4-7 presents the annual costs associated with thermal

incineration which were updated to February 1992 dollars by the use of equipment cost indices.2

The table indicates that direct costs amount to $574,600, indirect costs sum to $126,500, and total

annual costs equal $701,100. In contrast to adsorption and absorption, the highest cost impact

4-3

TABLE 4-2. OPERATING AND LABOR REQUIREMENTS USED TO

CARBON ADSORPTION ESTIMATE ANNUAL COSTS FOR FLUTDIZED-BED

Item ~~

Requirement

.

Carbon required

Desorption fuel needs

Column pressure drop

Nitrogen needs

Carrier gas electrical

Operating labor

Maintenance labor

Nitrogen cost

Control efficiency

175 lb/1,000 cfm

4,000 BTU/lb of lubricant recovered

6 inches water

0.05 scfAb of lubricant recovered

12 kWh/hr

0.5 man-hr/shift

0.5 man-hr/shift

$1.10/1,OOo scf

95%

4-4

TABLE 4-3. CAPITAL AND ANNUAL COSTS FOR FLUIDIZED-BED CARBON ADSORPTION'

Item Annual. Unit

Quantity cost ($1 cost ($1

Total Capital Investment

Direct Annual Costs

Raw Materials Carbon replacementb Carbon reactivationb

Utilities Electricity Cooling water Nitrogen

Operating Labor and Supervision

Maintenance Labor Materials

Total Direct Annual Costs

Indirect Annual Costs

Administrative Costs .

Overhead

Capital Recovery

Total Indirect Annual Costs

Total Annual Cost

3,090,000

350 lb 7.00Pb 2,450 3,150 lb 1.10Pb 3,500

2.37 x lo5 kWh 0.06kWh 14,200

11,556 scf 1.10/1,OOo scf 13

611 man-hr 13.12hr 8,ooO

5.53 x lo6 gal 0.20/1,000 gal 1,100

531 man-hr 14.5Obr 7,700 (100% of 7,700

maintenance labor)

44,700

(4% of capital investment) 123,600

14,000

(16.28% of capital investment) 503,000

(60% of OL, SL, ML, and MM)

640,600

685,300

Yosrs are in May 1992 dollars. bsased on assumption of regeneration once per year with 10 percent losses.

4-5

TABLE 4-4. OPERATING AND LABOR REQUIREMENTS USED TO ESTIMATE ANNUAL COSTS FOR OIL ABSORPTION

Item Reauiremen t

Wash oil Flow rate Heating capacity Total inventory

Heat generation

Vacuum pumps (2 )

Column pressure drop

Operating labor

Maintenance labor

Absorber oil

Control efficiency

45 gpm 0.65 BTU/lb"F 1,225 gal

electrical

30 hp each

10 inches water

2.0 man-hr/shift

1.0 man-hr/shift

$l.ZO/gal

95%

4-6

TABLE 4-5. CAPITAL AND ANNUAL COSTS FOR OIL ABSORPTIOW

Item Annual Unit

Quantity Cost($) Cost($>

Total Capital Investment

Direct Annual Costs

Raw Materials Absorber oil

Utilities Electricity Cooling water

Operating Labor and Supervision i

Maintknance Labor Materials

Total Direct Annual Costs

Indirect Annual Costs

Administrative Costs

Overhead

Capital Recovery

Total Indirect Annual Costs

Total Annual Cost

300 gal

9.24 x Id k w h 8.96 x lo6 gal

2,444 man-hr

1,063 man-hr (100% of

maintenance labor)

1.20/gal

O.O6/kWh 0.20/1,000 gal

13.12hr

14.50/hr

(4% of capital investment)

(60% of OL, SL, ML, and MM)

(1 6.28% of capital investment)

3,064,000

360

55,400 1,800

32,100

15,400 15,400

120,500

122,600

37,700

498,800

659,100

779,600

‘Costs are in May 1992 dollars.

4-7

TABLE 4-6. OPERATING AND LABOR REQUIREMENTS USED TO ESTIMATE ANNUAL COSTS FOR THERMAL AND CATALYTIC INCINERATORS

Item Requirement

Auxiliary fuel - natural gas Thermal 310 s c h Catalytic 200 scfm

Heat recovery Thermal Catalytic

System pressure drop Thermal Catalytic

Operating labor '

Maintenance labor

Control efficiency . Thermal

Catalytic

70% 50%

15 inches water 8 inches water

0.5 man-hrhhift

0.5 man-hr/shift

99% 95%

Volume of catalyst bed 40 f?

Precious metal catalyst . $3,OOo/ft3

4- 8

I

TABLE 4-7. CAPITAL AND ANNUAL COSTS FOR THERMAL INCMRATION'

Annual Unit Item Quantity cost($) Cost($)

Total Capital Investment

Direct Annual Costs

Utilities Natural gas Electricity

Operating Labor and Supervision

Maintenance Labor Materials ,

Total Direct Annual Costs

Indirect Annual Costs

Administrative Costs

Overhead

Capital Recovery

Total Indirect Annual Costs

Total Annual Cost

615,500

1.58 x lo8 scf 3.30/1,000 scf 521,400 4.96 x I d kWh O.O6/kWh 29,800

611 man-hr 13.12b.r 8,000

531 man& 14.50h.r 7,700 (100% of 7,700

maintenance labor)

574,600

(2% of capital investment) 12,300

14,000 . (60% of OL, SL, ML, and MM)

(16.28% of capital investment) 100,200

126,500

701,100

'Costs are in May 1992 dollars.

4-9

I

for thermal incineration is associated with direct costs, especially utilities, due to the auxiliary

fuel (natural gas) requirement. The high natural gas requirement is directly related to the low

VOC concentrations that are typically associated with rolling mill emissions (in this example 80

ppmv - see Table 4-1).

4.2.4 Catalytic Incineration

Costs for catalytic incineratm control were derived from the same published EPA cost

literature used for thermal incinerator^?'^ Previously shown Table 4-6 lists the equipment

parameters used to derive annual costs for catalytic (and thermal) incineration. Table 4-8

presents the annual costs associated with catalytic incineration which were updated to February

1992 dollars by the use of equipment cost indices? The table shows that direct costs amount to

$444,900, indirect costs sum to $127,800, and total annual costs equal $572,700. As with

thermal incinerators, note that the highest annual cost impact is associated with direct costs,

especially utilities, due to the auxiliary fuel (natural gas) requirement. The high natural gas

req&ment is, as stated before, directly related to the low VOC concentrations that are typically

associated with rolling mill emissions. Here, however, natural gas costs are less than for thermal

incineration due to the presence of a catalyst.

4.3 LUBRICANT SUBSTITUTION

This section contains cost data for implementing lubricant substitution as a VOC emission

control method. In order to consider lubricant substitution, many elements of unknown cost must

be considered. For this reason, a complete profile of the capital and annual costs associated with

lubricant substitution is not given here. As stated in Chapter 3, the only nonferrous rolling

operation to have experimented with lubricant substitution is the aluminum foil industry. This

is because aluminum foil rolling oils typically have a higher vapor pressure than other nonferrous

rolling oils and thus higher lubricant volatilization? As such, all qualitative and quantitative

information contained here apply only to the aluminum foil industry.

The exact capital and annual costs for lubricant substitution are difficult to detennine for

a specific facility due to all the unknowns associated with changeover. Table 4-9 lists the general

4-10

TABLE 4-8. CAPITAL AND ANNUAL COSTS FOR CATALYTIC INCINERATIOW

Item Annual Unit

Quantity Cost($) cost ($1 Total Capital Investment

Direct Annual Costs

Raw Materials

Utilities

Catalyst replacementb

Natural gas Elecmcity

Operating Labor and Supervision 1

Maintenance Labor Materials

Total Direct Annual Costs

Indirect Annual Costs

Administrative Costs

Overhead

Capital Recovery

Total Indirect Annual Costs

Total Annual Cost

40 f? 3 ,000/ft3

1.02 x lo8 scf 3.30/1,000 scf 2.63 x 16 k w h 0.06kWh

611 man-hr 13 .12h

531 man-hr 14.50hr (100% of

maintenance labor)

(2% of capital investment)

(60% of OL, SL, ML, and MM)

(16.28% of capital investment)

608,000

69,100

336,600 15,800

8,000

7,700 7,700

444,900

14,800

14,000

99,000

127,800

572,700

‘Costs are in May 1992 dollars. bAssume a two year catalyst lifetime and 10 percent interest (CRF = 0.5762).

4-11

TABLE 4-9. GENERAL ASSUMPTIONS AND COST FACTORS USED TO DERIVE LUBRICANT SUBSTlTUTION COST IMPACT

Item Specified Value

Annual emission rate

Lubricant sump capacity

Lubricant replacement frequency

Kerosene cost

Linear paraffin cost

Waste kerosene value

Lubricant density @ 60.O"F

Lubricant use reduction

200 tons

800 gal

every 14 days

$1 .oo/gal

$1.44/gal

$0.64/gal

$6.36 lbs/gal

10-60%'

Tor purposes of showing lubricant substitution costs, lubricant use reductions of 10,20.30,40,50, and 60 percent were considered.

4-12

assumptions and average costs (in May 1992 dollars) used to estimate the annual costs associated

with lubricant substitution from kerosene to normal paraffm for a single aluminum foil rolling

mill. Table 4-10 contains the algorithm that was used to determine the annual costs associated

with lubricant purchases for an example emissions reduction of 30 percent. Finally Table 4-1 1

presents the estimated lubricant use savings and annual costs at six different levels of lubricant

use reduction. Although lubricant use is reduced, annual costs are increased due to the higher

cost of linear paraffm compared to kerosene. Note that an annual cost savings occurs at a

lubricant use reduction of greater than 50 percent. Here, lubricant use savings are large enough

to offset the increased cost of linear paraffm oil.

It should be stressed that the costs presented in Table 4-10 do not include the research

and development required to implement lubricant substitution. Nor do they include costs for

downtime (and thus lost production) needed to conduct pilot-scale tests of new lubricant

formulations. R&D b d downtime costs are difficult to determine because every rolling mill is

different and requires different lubricant propemes. It is uncertain whether all nonferrous rolling

mill's would be able to implement lubricant substitution, although many aluminum foil mills have

had much success in switching from kerosene to linear paraffms.

4-13

TABLE 4.10 EXAMPLE CALCULATION OF ANNUAL COST FOR LUBRICANT SUBSTITUTION

Basis: - one year of operation - annual emission of 200 tons/yr - 30 percent emission reduction - lubricant replacement every two weeks - 800 gallon sump capacity - 10 percent annual interest rate for working capital - lubricant density = 6.36 lbs/gallon

Total oil purchased = W m lubricant plus lost emissions

Total kerarem purchased = 26 (800 gallons) + 200 ton I .

= 83,693 gdlons/yr 1

2,OooIbs gal ( ton ) (6.36 Ibs) Total paraffin p u r c h e d = 26 (800 gallons) + 0.7 (200 ton)

= 64,825 gallonslyr

Oil cost differential = parafin purchased x paraffin cost - kerosene purchased x kerosene cost = (64,825 gallons) ($1.44/gdlon) - (83,693 gallons) ($l.OO/gallon) = $9,655/yr . .

Interest on working capital = oil cost werential x interest rate = 9,655 (O.lO/yr) = $966

Total ann& cost = oil cost daference plus interest on working capital

Total a n d cost = $10,621 = $9,655 + $966

4- 14

TABLE 4-11. ANNUAL COSTS FOR LUBRICANT SUBSTITUTION AT VARIOUS LUBRICANT USE REDUCTIONS

Lubricant Use

Reduction

Annual Lubricant Use Savings

(gaVyr)

Annualq4‘ cost ($1

10%

20%

30%

40%

50%

60%

6,289

12,579

18,868

25,157

3 1,446

37,736

28,000

18,900

9,700

600

(8,500)

(17,700)

‘Costs do not include research and development costs for implementing lubricant substitution. “costs in parentheses ( ) are actual savings - negative costs - from reduced lubricant usage. “costs are in May 1992‘dollars.

4- 15

4.5 REFERENCES

1. US. Environmental Protection Agency. Volatile Organic Compound Control at Specific Sources in Louisville, KY, and Nashville, TN. EPA-904/9-81-087. Region 4, Atlanta, GA. December 1982.

2. "Chemical Engineering Plant Cost Index and Marshall & Swift Equipment Cost Index" in Chemical Engineering, Volume 99, Number 5. McGraw-Hill, New York, NY. May 1992.

3. U.S. Environmental Protection Agency. Handbook: Control Technologies for Hazardous Air Pollutants. EPA-625/6-91/014. Air and Energy Engineering Research Laboratory, Research Triangle Park, NC. June 1991.

4. U.S. Environmental Protection Agency. OAQPS Control Cost Manual. EPA-450/3-90- 006. Fourth Edition. Office of Air Quality Planning and Standards, Research Triangle Park, NC. January 1990.

5. Teleconference between V. Middleton of Olin Brass Company in East Alton, IL and S . Snow of Alliance Technologies Corporation. March 16, 1992.

4-16

I ’

APPENDIX A

TRIP REPORTS

A- 1

YA J ~ V A ALLIANCE giy'v~ Technologies Corporation

Date: May 13, 1992

Re: Site Visit - Olin Brass Corporation, East Alton, IL Nonferrous Metal Rolling EPA Contract 68-DO-0121; Work Assignment 1-30 Alliance Reference No. 1638030

From: W. Scott Snow .?.t: Ad. Alliance Technologies Corporation

To: Joseph Myers ' OAQPS/ESD/ISB (MD-13) U.S. Environmental Protection Agency Research Triangle Park, NC 2771 1

I. PURPOSE

The purpose of this visit was to gather background information on the metal roiling process including information necessary to characterize the process parameters, VOC emissions, emissions control techniques, and control costs.

'J. PLACE A.ND DATE

Olin Brass Corporadon 427 N. Shamrock Street East Alton, IL 62024 (618) 258-2000

February 10, 1992

III. ATTENDEES

Olin Brass Corporation ( O h ) L. William Mason, Director, Energy and Environmental Services Michaei L. Roark, Manager, Environmental Affairs

Olin (continued) Daniel J. Angeli, Engineer Associate Verne L. Middleton, Hydraulic and Lube Engineer - Mill Products Engineering

Alliance Technologies Comoration (Alliance) W. Scott Snow, Environmental Engineer Phil J. Marsosudiro, Environmental Engineer

IV. DISCUSSION

A. Summan

Alliance’s visit to O h Brass began around 9 a.m. with Mr. Mike Roark and Mr. Bill Maxson at the OLin facility located on Highway 3. During the introductory meeting, Alliance and OLin reviewed the agenda for the day, and Alliance requested that O h provide copies of the plant’s air and wNer operating permits as well as facility drawings illustrating the location of the rolling mills and other processes within the Olin facdity. Alliance then toured the #3 Plant, which contains several specialty cold rolling mills, and the Casting Plant which contains a hot mill. After the tour, Alliance met with MI. Dan

. .4ngeli, engineering associate, to discuss operations at OLin’s two main cold roUlng facilities. After the meeting, Alliance proceeded to lunch for discussion with MI. Verne Middleton, hydraulic and lube engineer. After lunch, Alliance toured the two cold rolling facilities (Brass Mill, Zone 1; and Building 280). The tour was followed by a closing meeting with MI. Angeli, Mr. Maxson, and Mr. Roark. During this meeting, Alliance and. Olin assembled information requested in the initial questionnaire and contmed plans for review of :he trip report and confidential business information (CBI).

B. Olin Brass Market Profile

Olin Brass is one of the nation’s largest producers of rolled copper and copper alloys. Major end-users for Olin rolled alloys include the transportation industry, the U.S. Mint. and the military. Other end-products may be sent to rerollers or other distributors. Copper and copper alloy coils are shipped to customers or other fabricators in various sizes, but the typical coil exiting a mill stand weighs approximately 11,OOO to 14,000 lbs, with a width of approximately 30 inches and outer and inner diameters around 4 feet and 16 inches, respectively.

2

C. Manufacturing Supplies

O h Brass uses many different raw materials in their rolled alloy manufacturing process. The main raw material is metal scrap, including copper, tin, brass alloys of copper and zinc, and other metals. Rolling oils make up another major category of raw materials. Two types of petroleum hydrocarbon oil and an oil-in-water emulsion are used for lubrication and cooling. The oil-in-water emulsion typically contains less than 10 percent oil. In addition, both the hydrocarbon oils and the oil-in-water emulsion contain various proprietary additives in amounts less than 10 percent of the total lubricant volume. None of the rolling lubricants must have Food and Drug Administration (FDA) approval.

According to material safety data sheets (MSDSs), vapor pressures range from "nil" to less than 0.1 " H g at 20°C for the two hydrocarbon lubricants used at the facility. The vapor pressure of the oil-in-water emulsion was not determined. According to Mr. Roark, none of the rolling lubricants are considered volatile organic compounds (VOCs) for the purposes of the Illinois state pennit process. However, EPA definitions for VOC state no such vapor pressure qualification.

i

Olin reported that "nearly all" of the oil used in the rolling process is collected, cleaned, and reused at the plant. An intricate collection system that includes hooding, lubricant recovery from exhaust gases, and lubricant spillover pits is in place on most of Olin's rolling mills. An exact estimate of the amount of lubricant lost per year to the atmosphere, wastewater, and in the exit coils was not available.

D. Manufacturing Process Parameters

The processes examined during this plant visit included hot rolling, cold rolling, annealing, and finishing of copper and copper alloy products. These processes and several intermediate processes are shown in Attachment 1, taken from promotional material published by Olin Brass.

In the hot rolling process, cast metal bars, measuring approximately 6" x 30" x 25', are heated to around 9 0 ° C (1650°F) then transferred to the single hot rolling rmll at the Olin facility. In the hot d, the metal bar undergoes several passes (around 10 to 14) though a pair of steel work rolls which reduces the gauge thickness. The hot mill is reversible allowing the metal to be passed through the work rolls several times until shaped into a strip of approximately 3/8" x 30" x 460' at which time it is wound onto a coil. A jet water spray system serves only to cool the steel work rolls and is not designed to cool the rolled metal.

At this stage in the process, the metal surface is covered with a dark, rough layer of oxidation due to the high rolling temperatures in the presence of oxygen. The oxide layer is removed via a coil miller before further metal processing occurs at a cold rolling

3

mill. The coil miller uses a special knife that removes the outer layer of oxidation from the hot rolled coil. Normally, one pass through the milling machine is required to remove the layer of oxidation. After passing through the coil miller, the coil surface is shiny because the oxide layer has been removed, and scalloped in texture from the milling machine. After leaving the coil d e r , the coils are transported to the appropriate cold rolling mills.

The main processes occurring at the cold mill facility are rolling, annealing, and cleaning. Any given coil can cycle through the rolling/annealing/cleaning series one to four times before the metal is Sent to the packaging and shipping department. In addition, the coil may be cycled through the cold rolling step several times before annealing is required. In general, coils can be rolled to around a 60 percent gauge reduction before annealing is necessary. For a given coil, the exact combination of rolling, annealing, and cleaning steps is a function of the desired product and of the equipment used.

Olin's East Alton,IL facility contains approximately 15 operating cold rolling mil ls, of which qbout 2/3 u s e m oil lubricant; the remainder use an oil-in-water emulsion. Lubricant is continuously applied, by either spray or flood technique, to different parts of the rolling mill while the copper coil is being rolled. The largest amount of oil (or emulsion) is sprayed at the roll bite (or nip) for metal lubrication and cooling, but a portion of lubricant is also applied to the steel work rolls to cool them. A small amount

'.of lubricant is added, via drip application, just before the take-up reel of the coil to prevent the wraps of the coil from scratching each other. Mill operators control the application of the lubricant by means of numerous, hand-operated valves that regulate the flow of lubricant to each required area and each section of the rolls. According to Mr. Angeli, the proper application of lubricant to different parts of the rolls is essential to the production of even, properly-sized coils without defects. Sufficient training and experience is necessary to ensure that the metal is produced as desired.

After a coil is removed from the cold mdl, it is taken through the annealing process. During the annealing process, the rolled metal is heated above its recrystallization temperature, reducing the internal saesses created during cold rolling. Also during annealing, most of the lubricant on the coil is either vaporized or burned off. It has not been determined how much of the lubricant is driven off as vapor. After the annealing process is complete, the metal is either Sent to a mill for further cold rollin3 or directed to the packaging and shipping section for final production processes.

At Oh, annealing is accomplished in one of two manners; bell annealing or strip annealing. In the bell annealing process, the rolled coil is placed in an enclosed chamber and heated for approximately 24 hours. This annealing process is typically reserved for the final product when no further cold rolling will occur. During the strip annealing process, the metal s ~ p is unwound and passes through an in-line alkaline cleaning tank to remove residual oil from the surface. After passing through the annealing, cooling, and pickling pomon of the strip annealing process, the metal is recoiled. At this point, the

4

I '

annealed copper is either sent to another cold rolling mill or is sent to the shippin_g and packaging department. The end-result of either annealing process is a nearly oil-free metal coil with improved ductility.

E. Lubricant Use. Recoverv. and Recycling

The lubricant recovery and filtration system at Olin is considered a "closed-loop" system. Lubricant is applied at the mill to the coil and work rolls and is recovered by sumps or mist collectors. hiill overflow is captured below the stand in a sump located in the "basement" of the facility. Lubricant mist is captured by hoods, which surround the roll stand, and routed to a mist collector where the oil is collected and returned to the sump. Nearly all of the m i l l s employ some type of mist collection device with flow rates ranging fiom 15,000 scfm to greater than 40,OOO scfm.

Each mill at the cold rolling plant has its own lubricant cleaning system, except for two, closely-located m i l l s that share one device between them. The lubricant cleaning system is designed to take the lubricant recovered kom the sump, clean out metal fines and other impurities, and return the lubricant to the mill for reuse. Various cleaning systems are used for the different mil ls. The cleaning device at some mi l l s consists of a centrifugal separator (cyclone) located in series with a filter. For other mi l l s , a paper and diatomaceous earth filter is used. Lubricant recycling system pumps can operate at a maximum of approximately 250 gallons per minute.

Some estimates of lubricant oil losses have been made by Oh, the results of which are discussed in the following paragraphs. Oil recovery at O h was initially dnven by economic incentives rather than environmental reasons. This is because the lubricant oil used at Olin has a very low vapor pressure and is not considered a VOC for permitting purposes by the State of Illinois. Olin has never conducted stack tests to measure VOC emissions or vapor-phase emissions of their lubricant oil. O h maintains an active lubricant loss reduction program and estimates that oil losses are generally very low. However, when estimating losses, only carryout losses (oil on the coil after the coil leaves the null) and losses through the mist eliminator were considered. Mist or vapor losses to the plant atmosphere and liquid losses to the plant floor were not included.

O h provided lubricant mass-flow diagrams for several of the oil and emulsion m i l l s at the plant. Calculations based on two of the oil rmll flow diagrams indicate that hourly oil losses by carryout and through the mist eliminator are less than or much less than 0.1 percent of the total oil used. These flow diagrams show that the greatest fraction of oil loss consists of oil carried out on the coil. Minimal losses are attributed to the mist eliminator because the mass flow to the mist eliminator is relatively small and the removal efficiency of the mist eliminator is estimated to be in excess of 99 percent.

5

According to O h , the mass flows given in the diagrams are estimates, and no stack tests have been conducted at the mist eliminator exits. Any total suspended particulate (TSP) calculations are made on the basis of mass balance going into the mist eliminator and assumed collection efficiencies. Nearly all of the mi l l s have capture devices routed to some type of mist eliminator. Different types of mist eliminators used at the O h m i l l s include metallic Wire meshes and canister-type filters. They are designed to remove suspended oil droplets from the exhaust saeam.

F. Observations at the Plant

ALhance observed a fine mist rising from the rolling area of many of the d s . A much smaller amount of mist was seen rising from above the metal coils. ‘A noticeable cloud of mist was observed lingering at the ceiling level, approximately 70 ft. above the plant floor. Machinery surfaces in the plant were covered with a fine coating of oil, presumably hom the settling of the oil mist. The floor of the plant was also oily, presumably due to oil canyout on the coils and other drips or spills. Puddles located near lubricant reclamahon equipment and near m i l l s were confined or absorbed with absorbent pillows or sausages.

Within the cold rolling plant, there was a noticeable odor from the lubricant vapor in- the air. However, workers at the plant did not wear any respiratory equipment such as masks or filters. According to the MSDSs, respiratory protection is not normally required for the oil lubricant used in adequate ventilation at the mi l l s . An air purifying respirator is recommended, but not required, for the oil-in-water lubricant used.

G. Emissions

As mentioned previously, O h does not estimate the amount of VOC emitted from their plant because the lubricants used for rolling are not considered VOCs by the State of Illinois. Permits were available for several of the rolling mil ls , however, none of the permits contained VOC emission limits but most did estimate the amount of particulate matter released to the atmosphere. For permitting purposes, the composition of particulate matter was assumed to be 100 percent mineral oil.

O h also reported that the facility’s Form R does not include any emissions from the rolling mil ls . Emissions covered in O h ’ s Form R are all from other areas of the plant. According to Oh, the rolling mi l l s do not release any SAIt4 313 substances. Also, O h ’ s NPDES permit makes no mention of VOC.

Accordingly, with the above assessment that .VOCs are not released from Oh’s East Alton,IL rolling mil ls, O h has not attempted to install VOC connol equipment at

6

the plant. Therefore, no past VOC control experiences or cost data were available for review.

H. Maintenance

The O h rolling m i l l s usually have an annual shutdown every July. All m i l l s are cleaned, inspected, and repaired at this time. O h uses no solvents during the cleaning process. Other equipment maintenance and cleaning is done on an as-needed basis. General cleaning practices are utilized to remove lubricant and grime from the plant floor and elsewhere.

7

A ALLIANCE 147444 Technologies Corpora:ion

Date: May 18, 1992

Re: Site Visit - Reynolds Metals Company: Flexible Packaging Division, Richmond, VA Nonferrous Metal Rolling EPA Conuact 68-DO-0121; Work Assignment 1-30 Alliance Reference No. 1638030

1 1

From: W. Scott Snow +v'- 4~s. Alliance Technologies Corporation

To: Joseph Myers OAQPS/ESD/ISB (MD-13) U.S. Environmental Protection Agency Research Triangle Park, NC 2771 1

. - I. PURPOSE

The purpose of this visit was to gather background information on the metal rolling process including information necessary to characterize the process parameters, VOC emissions, emissions control techniques, and control costs.

II. PLACE AND DATE

Reynolds Metals Company - Flexible Packaging Division 7th & Bainbridge Sueets Richmond, VA 23224 (804) 281-5299

February 19, 1992

III. ATTENDEES

Revnoids Metals Companv (Remolds) Kenneth W. Bourne, Plant Engineer, Richmond Foil Plant Kerry R. Dean, Plant Manager, Richmond Foil Plant Forest L. Keister, Jr., Environmental Coordinator, l%chmond Foil Plant

6220 Ouadrangle Drive . Suite 100 . Chaoel Hill, Norrh Carolina 375;" . (919, 492-2471

A T2C Company

I ' Revnolds (continued) Tomas A. Loredo, Division Environmental Engineer Michael F. Tanchuk, Manager, Air Quality and Technical Studies, Corporate

Environmental Control

U.S. Environmental Protection Agency (EPA] Al Vervaert, Chief, Standards Support Section Joseph Myers, Environmental Engineer Karen Bell, Environmental Engineer

Alliance Technologies Corporation (Alliance) W. Scott Snow, Environmental Engineer

Tv. DISCUSSION

A. S u m " 1

Alliance and EPA's visit to the Richmond Foil Plant began around 10:15 a.m. with all attendees listed present. During the introductory meeting, Reynolds provided an overview of the plant operations, a RACT determination overview, and a general outline

. for the day's agenda. Alliance and EPA reported on the current stam of the Work . Assignment and informed Reynolds of what information needed to be gathered during the visit. Afterwards a general discussion was held in which questions were answered concerning confidential business information (CBI), health and safety procedures, and other areas of concern. Alliance and EPA then toured the Richmond Foil Plant which contains three general areas of production: household foil, light-gauge foil for lamination and printing, and other consumer products. After the tour was complete, all those in attendance met for a last session to answer any final questions and to layout the. next steps.

B. Richmond Foil Plant Market Profile

The kchmond Foil Plant is a relatively large facllity in relation to others nationwide with approximately one million square feet of floor space and nearly 53,000 metric tons of production in 1991. Products include household aluminum foil (Reynolds Wrap), light-gauge foil for lamination and printing, and other consumer products. The household foil production capacity is large enough to supply nearly all of the consumer demand on the East Coast for Reynolds Wrap. Typical input rolls weigh around 32,000 lbs at the maximum widths avadable. Light-gauge foil products are used in converter operations (lamination and printing) for packaging materials with an average input roll weighing between 26,000 and 27,000 lbs in variable widths. The consumer products area

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manufactures aluminum foil to consumer specifications that depend on the application, therefore, a typical roll from this area will vary greatly in weight as well as width.

c. Manufacturing SuDDlies

Reynolds’ Richmond Foil Plant uses two main types of raw materials in their aluminum foil manufacturing process: they include coiled aluminum and rolling lubricant (lubricant, coolant, and oil are used interchangeably in this report). Coiled sheets of aluminum manufactured at other Reynolds’ facilities serve as the rolling mill input for foil operations. These input coils are cycled through a series of breakdown, intermediate, and finishing mi l l s to obtain the fmal desired product. A peuoleum hydrocarbon oil (hear paraffin) semes as the lubricant and functions as both lubricant and coolant in all foil rolling operations. Previous to the RACT determination of 1987, Reynolds had used kerosene as the rolling lubricant. Various proprietary additives are used with the linear paraffin oil, the specific properties of which depend on the application they are required for. The total volume of additives is small, typically less than 10 percent of the t o u l lubricant volume.

According to Reynolds’ personnel, the physical properties of the linear paraffin oil are as good or better than the kerosene lubricant that was used before 1987. Vapor pressure-is lower and flash point is higher for the linear paraffin oil. These propemes

. have led to reduced vapor generation and lower material costs because more of the lubricant can be captured and recycled. The lubricant is considered a VOC by E P 4 regulations, however, it is somewhat less volatile than the kerosene previously used at the foil plant. The installation of the lubricant reclamation system (see discussion in secuon E of this trip report) employed by the Richmond Foil Plant was a major retrofit effort. However, Reynolds believed the benefits associated with the reclamation system would far exceed the costs. The benefits include nearly unlimited reuse of ,lu:ubricmt, reduced waste oil generation, and lower waste oil disposal costs.

D. Manufacturing Process Parameters

The processes examined during the plant visit to Richmond,VA include various steps of cold rolling aluminum sheet to produce foil and converter products. Plant operations examined include breakdown, intermediate, and fmishmg d s as well as annealing ovens designed to accomplish the goal of a clean, unmarred foil surface product. These operations are discussed in this section.

As discussed previously, there are three product areas of the Richmond Foil Plant that include household foil, light-gauge foil, and packaging products. The basic process flow in each production area is essentially the same, therefore, the discussion will focus on the household foil area and draw comparisons to the other areas. The household foil

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area contains three cold rolling d s labeled the breakdown mill, intermediate mill, and finishing mill. The light-gauge area contains one breakdown, one intermediate and two finishing rmlls. In the oldest mill section, where various made-to-order foils are produced, there are approximately nine mil ls , one of which being an intermediate rmll the rest finishing mills. All of the mil ls are considered four-high single stand mil ls.

The first step in foil production is the breakdown mill where the coiled aluminum input is rolled an average of three times. Here, thick input gauges are reduced to a more workable thickness. Nexq an average of two passes on the intermediate mill prepares the coil for one final rolling to complete the finished product. One final pass on a finishing mill is the last step in household foil production where two strips of intermittent foil are combined and rolled together. The two layers exit the machine and are wound onto one coil. This two-layered rolling results in the household foil having a shiny side and a dull side. A separator mill (no lubricant required) is then employed to separate the two layers of foil onto two coils so they can be sent to an annealing oven for final anneal.

h e a l i n g usually occurs twice in the production of foil. The first annealing process is performed at the input aluminum coil stage, prior to the first rolling stage. The second annealis the finish anneal which occurs when all rolling stages are complete. During the annealing process, the rolled metal is heated above .its recrystallization temperature, reducing internal stresses created during cold rolling. Also during anneahg, nearly all of the residual lubricant left on the coil is either vaporized or burned off. It has not been determined how much of the lubricant is driven off as vapor. After the finish

. anneal and subsequent cooling of the coil, the coil is directed to the packaging and shipping section for final production processes. Annealing times may vary between 20 and 30 hours depending on the specific metal propemes desired and at what stage the foil is during production.

Other rolling mill areas at Reynolds follow the same general processes as the household foil. After the input aluminum cod annealing, the coil is sent to an inidal breakdown mill. From there intermediate rolling passes are made on other m i l l s . Finally, the coil goes through a frnshing pass and then to the finish anneal. For a given coil, the exact combination of rolling d s and annealing parameters is a function of the desired product and equipment loadmg. It was noted that none of the m i l l s was reversible, therefore, each roll pass required re-setting of the mill input coil.

During various rolling stages the h e a r paraffin oil is used to lubricate and cool the rolling mill machinery and the aluminum itself. The oil serves to reduce hc t ion at the roll nip and extract heat generated during the rolling process from both friction and internal stresses. The oil is also designed to cool the steel work and back-up roUs to prevent their deformation or buckling under the extreme loads. The lubricant flow rate per mill depends on several factors including mill speed, gauge reduction, lubricant temperature, and application technique. The breakdown and intermediate d s at Reynolds were observed using a narrow stream of lubricant spray applied evenly across

the roll nip. On the finishing mill in the household foil area, lubricant was observed gushing out, via the flood technique, at a noticeably higher rate than that for the breakdown or intermediate mills. Also, a small amount of lubricant was applied, via the drip technique, between the layers of coil to prevent them hom sticking to each other and ease the separating operation. Improving the application of the lubricant is an ongoing activity; sufficient training and experience is necessary to ensure that the metal is produced as desired. In 1987, a RACT determination was performed at the foil plant which determined the best applicable lubricant for VOC emissions reduction. This RACT determination is discussed in the next section of this trip report-

E. RACT Determination

Reynolds’ selection of linear paraffin for rolling lubricant was derived from a Reasonably Available Control Technology (RAW demonstration performed in 1987. Several emissions cone01 and/or reduction options were examined and evaluated and the results concluded that lubricant changeover was the most viable option for their operations. ?n,e old lubricant consisted of a kerosene-based mixture which had long been the standard in rolling operations. Other control techniques examined for RACT were oil absorption and carbon adsorption. The conclusions and results for each control option are discussed in this section.

Currently, the add-on control devices at the Richmond Foil Plant consist of mist eliminators on every mill or group of mills and one centdugal impactor located on one mill in the household foil area. These devices were originally installed for opacity control and are not designed for VOC vapor control. The capture devices are also not very efficient especially on the older d s (approximately 70 percent on newer mills). Airflows range from 6,000 to 40,000 acfm for the small to large mi l l s . MI. Tanchuk stated that for aluminum sheet mills, flow rates can range fiom 80,000 to 100,000 acfm.

Oil absorption was considered as an applicable emissions control technique. Multiple rolling plants overseas use this technology as well as one plant in Canada, however, no plants in the United States currently employ an oil absorber for emissions control. Severe limitations exist in the areas of retrofit (and retrofit cost), reuse of lubricant oil after absorption, and FDA requirements which render t h ~ s technology not feasible. An oil absorption reuofit system is very large (some 60 feet tall) and heavy. Auxiliary equipment includes ductwork, hooding, and support structure. Size and space limitations were detrimental to oil absorption for the foil plant because the building was not erected with these retrofit expectations. Another consideration involves the reuse of the waste lubricant oil after absorption. The waste lubricant typically cannot be reused after the absorption process which would have resulted in a loss of income for Reynolds because the kerosene lubricant could be re-sold after use as low-grade fuel. Also, absorption tends to change the nature of the lubricant by reducing the additives and adding the step of product reformulation before reuse as a lubricant Finally, FDA

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requirements would have had to be met for the recycled oil. For all these reasons oil absorption was abandoned as a possible control option.

Carbon adsorption was also considered for emissions control at the Richmond Foil Plant, however, limitations were found that included retrofit, retrofit cost, and low VOC concenmtions. As stated previously for oil absorption retrofit requires ductwork, hooding, and support structure as well as space and size examinations. The major impediment to adsorption is the low VOC concentration associated with rolling mill emissions. Large airflows are required to exhaust a majority of the vapor and mist associated with the emissions which reduces the VOC concentration. Other disadvantages to the adsorption process are the frequent carbon desorptions required and the rapid fouling that VOC mist may cause. Only one unit is known to be installed on a new rolling mill in the United States (i-e., no retrofit applications are known). Problems have been encountered with this system since its installment and do not appear as though they will ever be corrected. Therefore, carbon adsorption was also abandoned as a possible control option.

The final emissions control technique is not truly considered control but more a process change which results in source reduction. Lubricant substitution to a less volatile compound can inherently reduce rolling mill emissions by increasing the heat capacity and lowering the vapor pressure of the oil. Linear paraffin oil was the lubricant of choice for substitution at Reynolds’ Richmond Foil Plant. Factors affecting the degree of

.. emissions reduction via lubricant substitution include lubricant temperature and application rate. Advantages to the linear paraffin include equal or better foil product quality, FDA approval, less flammability, and lower volatility. Disadvantages are the requirements for recirculation system equipment and for research and development (R&D) on the new oil. Since the paraffin oil cannot be re-sold as the kerosene could, recirculation systems were designed to capture, filter, cool, and distill the linear paraffin so that it could be reused. R&D was required to reformulate the oil with additive packages to ensure the best product from each mill.

From information gathered during the study of all three control options, ELACT was determined to be lubricant substitution from kerosene to a linear paraffin oil. In 1987, Reynolds had four new filtration systems installed to filter and cool the oil and recirculate it back to the rolling mil ls . Each system was designed to Nter together r m l l s which use the exact same lubricant composition. A distillation unit was also retrofitted to recover usable oil from the waste oil generated in the filtering system. This oil recovery offsets some of the losses associated with lubricant substitution, namely income lost from the sale of used kerosene. The linear paraffin cannot be re-sold as a waste fuel oil, thus oil recovery is an economically feasible solution. In addition, the distdlation system provides a longer lifetime for the lubricant and reduces off-site disposal costs associated with waste oil.

The installment costs for these reclamation systems was approximately $2,000,00i in 1985, not including R&D costs. The systems required the addition of collectors, filters cooling units, oil tanks, and a distillation unit as well as the auxiliary equipment associated with each. In addition, other retrofit construction equipment (i-e., supports, structure) was installed.

F. Alliance and EPA Observations at the Richmond Foil Plant

A fine mist was frequently observed rising from the rolling area of the household foil mills. A building ventilation system served to remove this mist and vapor quite adequately from the work area. Machinery surfaces in the plant were covered with a h e coating of oil, presumably from the settling of the oil mist. The floor of the plant was also oily, presumably due to oil carryout on the coils and other dnps, splashes, or other losses.

Operating hours for the foil plant are 24 h/7 days per week (dpw) for household foil operations and anywhere from 24 hr/5 dpw to 24 hr/7 dpw for other foil operations. The fabricating and shipping department is located across the James River at the Richmond North PIant.

Reynolds estimates that greater than 130 tons per year of lubricant oil is lost to .. the oil filtration system’s fdkr media and must be disposed of. This represents a

significant amount of oil that can be fdtered, distilled, and reused. Also noteworthy, the fact that at least one annealing oven employs an add-on thermal incinerator to destroy oil vapor generated during the annealing process.

G. Emissions

Reynolds stated that no estimates are available as to the magnitude of the reduction in VOC emitted since changeover to the linear paraffin oil. Other studies have suggested that as much as 63 percent reduction is theoretically possible with a combination of reduced lubricant application temperature and paraffin oil. Reynolds stated that EPA Method 24 cannot be used since the oil is captured, filtered, and recycled. As stated previously, the foil plant does employ mist eliminators and one centrifugal impactor, however, these devices are mainly for opacity reduction not VOC control. w

Accordingly, with the previous assessment of lubricant changeover as RACT for the Richmond Foil Plant, Reynolds has not been required to install VOC add-on equipment at the plant. Therefore, no past VOC control experiences or cost data were available for review.

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H. Maintenance

Reynolds’ Richmond Foil Plant has a preventative maintenance system to ensure proper machine operation. Other repairs andor general cleaning duties are performed during the year on an as needed basis.

TECHNICAL REPORT DATA (Please read Instncctrons on the reverse before completing)

. REPORT NO. 2. 3. REC!PIENT'S ACCESSION NO.

453/R-92-001 I

. TITLE A N D SUBTITLE 5. REPORT DATE

CONTROL OF VOC EMISSIONS FROM NONFERROUS METAL JUNE 1992 ROLLING PROCESSES 6. PERFORMlNG ORGANIZATION CODE

. A U T H O R W 8. PERFORMING ORGANIZATION REPORT NO

W. Scott Snow, Philindo J. Marsosudiro - . PERFORMING ORGANIZATION NAME AND ADDRESS 10. PROGRAM ELEMENT NO.

Alliance Technolgies Corporation 100 Europa Drive, Suite 150 11. CONTRACT/GRANT NO.

Chapel Hill, North Carolina 27514 68-DO-0 12 1 , WA# 1-30

2. SPONSORING AGENCY NAME A N D ADDRESS 13. TYPE OF REPORT AND PERIOD COVERED

U.S. Envirnomental Protection Agency (MD-13) Emissions Standards Division 14. SPONSORING AGENCY CODE

Office of Air Quality Planning and Standards Research Traingle Park, North Carolina 27711

5. SUPPLEMENTARY NOTES i

ESD Work Assignment Manager: Joseph N. Myers, MD-13, 919-541-5428 6. ABSTRACT

This document was developed in response to increasing inquiries into the environmental impacts of nonferrous metal rolling which use oil as a lubricant and coolant in rolling operations. VOC emissions result from evaporative fugitive losses caused by heat generated in the rolling .processes. The focus of the document is VOC emission control techniques used by copper and aluminum rolling mills. provided for each of the control techniques addressed. The following control techniques are:

A control cost anaylsis is also

Carbon Adsorption Absorption Incineration Lubricant Substitution

7 . KEY WORDS AND DOCUMENT ANALYSIS

DESCRl PTO RS Ib. I DENTI FI E RS/OPEN ENDED TERMS IC. COSATI FieidiCroup

Air Pollution Aluminum Rolling Mills Carbon Adsorption Copper Rolling MIlls Lubricant Substitution VOC emission controls

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