Summary report - PPlastics recovery from waste electrical...
Transcript of Summary report - PPlastics recovery from waste electrical...
Plastics Recovery from Waste
Electrical & Electronic Equipment
in Non-Ferrous Metal Processes
Authors:
Frank E. Mark
Dow Europe, [email protected]
Theo Lehner
Boliden Mineral AB, [email protected]
A technical
paper from :
TABLE OF CONTENTS
SUMMARY ………………………………………………………………………………… 2
1. INTRODUCTION ……………………………………………………………… 31.1 WASTE ELECTRICAL AND ELECTRONIC EQUIPMENT (WEEE) ……………… 31.2 PLASTICS INDUSTRY ISSUES…………………………………………………… 31.3 NON-FERROUS METALS INDUSTRY ISSUES …………………………………… 31.4 PROGRAMME OBJECTIVES …………………………………………………… 4
2. WEEE CHARACTERISTICS ………………………………………………… 52.1 ELECTRICAL AND ELECTRONIC (E+E) WASTE ……………………………… 52.2 FEED SUPPLIED TO NON-FERROUS METAL RECYCLING PLANTS ……………… 62.3 WEEE AS A SECONDARY RAW MATERIAL …………………………………… 6
3. NON-FERROUS METALS PRODUCTION ………………………………… 73.1 ZINC FUMING FURNACE …………………………………………………… 73.2 KALDO FURNACE …………………………………………………………… 9
4. INTEGRATED WASTE MANAGEMENT (IWM) OF WEEE ……………114.1 WEEE PRE-TREATMENT ……………………………………………………114.2 WEEE FEED PREPARATION FOR THE TRIAL …………………………………11
5. TRIALS WITH WEEE: PCs ……………………………………………………125.1 RECYCLING OF PC SCRAP IN THE ZINC FUMING FURNACE …………………125.2 PRINTED CIRCUIT BOARD AND CABLE SCRAP RECOVERY AT
THE KALDO FURNACE ……………………………………………………………13
6. RESULTS …………………………………………………………………………146.1 METALS RECOVERY …………………………………………………………146.2 COAL SUBSTITUTION: ENERGY BALANCE FOR THE ZINC FUMING PROCESS …146.3 METALLURGICAL ASPECTS: ZN PRODUCT QUALITY …………………………156.4 EMISSIONS, MATERIAL AND MICRO-ORGANIC BALANCES …………………156.5 DESTRUCTION EFFICIENCY……………………………………………………16
7. ENVIRONMENTAL IMPACT …………………………………………………187.1 EMISSIONS TO AIR ……………………………………………………………187.2 EMISSIONS TO WATER ………………………………………………………187.3 DISPOSAL OF SOLIDS …………………………………………………………187.4 WORKPLACE SAFETY …………………………………………………………18
8. CONCLUSIONS …………………………………………………………………19
9. RECOMMENDATIONS…………………………………………………………20
10. ACKNOWLEDGEMENTS ………………………………………………………20
11. REFERENCES AND WEBSITES ……………………………………………21
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T E C H N I C A L R E P O R T
1. SUMMARY
A growing range of waste electrical and electronic equipment (WEEE) can now be
used as a feed stream in non-ferrous metal smelting plants. There are significant
environmental benefits, including the complete destruction of all micro-organic
compounds, and economic benefits both for the smelters in recovering valuable
metals, and for society in terms of reducing waste management costs.
The Association of Plastics Manufacturers in Europe (APME) and the Swedish
company Boliden Minerals AB carried out a joint project which demonstrates that the
use of scrap cable and printed circuit boards as secondary raw materials can be
extended to include other E+E equipment such as personal computers (PCs). Plant
performance and workplace safety standards are maintained, and emission levels are
unaffected. In the Boliden plant alone 15,000 tons per year of PC scrap could be
treated in this way.
Emerging requirements to reduce the volume of material going to landfill and
preserve valuable resources can be met more easily with this approach. Metal
recovery rates are high and the plastics content serves a dual function, both as a
reducing agent and as a source of energy for the smelting process.
Since the complete dismantling of WEEE is often neither ecologically nor
economically feasible, the more comprehensive approach of Integrated Waste
Management (IWM) is now preferred. Several different waste treatment methods,
including mechanical recycling, are combined in a way that achieves the optimum
balance of environmental, social and economic requirements. The report demonstrates
how the use of WEEE as a source of secondary raw materials in non-ferrous metals
smelting is a viable component of an IWM approach. It includes a review of
Boliden’s long experience of processing scrap cable and printed circuit boards, and
describes trials conducted with PC scrap.
Plastics Recovery from Waste Electrical & Electronic Equipment in Non-Ferrous Metal Processes.
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T E C H N I C A L R E P O R T
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1. INTRODUCTION
1.1 Waste Electrical and Electronic equipment
Approximately 6 million tons of waste electrical and
electronic equipment (WEEE) is generated in Western
Europe annually. Although it represents only 4% of the
municipal waste stream, with an average growth rate 3
times greater than that of municipal waste, the quantity of
WEEE generated is expected to double in the next
12 years. Factors contributing to this high rate of growth
are technical developments which shorten product life
cycles and reduction of WEEE inventories through
increased rates of collection.
Disposal of WEEE is considered to present substantially
more environmental problems than is the case with
municipal waste. Currently most WEEE is landfilled and a
small amount recycled or recovered. National directives
are now either in place or being prepared which impose
new requirements regarding the management of WEEE.
Central to this kind of change is a draft European Council
directive on WEEE which will require producers to take
responsibility for certain phases of the waste management
of their products. Among the key objectives of the draft
directive are the minimisation of hazards associated with
WEEE, a reduction in the volume of material going to
landfill and the preservation of valuable resources.
The 6 million tons of WEEE includes 675,000 tons of
plastics waste that is available for collection, and an equal
quantity of non-ferrous metals. The two types of material
are combined within the finished products, often in a
highly complex manner. This provides an opportunity for
the two industries to work together on new and
innovative methods of waste management which meet the
needs of all stakeholders, with a reduced environmental
impact and improved economics. This report describes
joint work carried out by the Association of Plastics
Manufacturers in Europe (APME) and a major non-
ferrous metals refining company, Boliden Minerals AB,
whose world-scale smelting complex is located in
Rönnskär, Sweden.
1.2 Plastics industry issues
From the plastics industry perspective, the first preference
for end-of-life products, when feasible, is re-use.
Individual components can be recovered for re-use by
dismantling. However, the pace of change in product
development of Electrical and Electronic (E+E)
equipment means that the global market for the re-use of
components is somewhat limited. Items that cannot be re-
used need to be treated in a manner which, overall, is both
environmentally and economically sustainable. Where
re-use is not possible, mechanical recycling can be a useful
option. Unfortunately this has severe limitations caused by
the difficulty of achieving acceptable product quality,
limited markets for recycled polymers, innovations in
polymer performance and consumer acceptance. These
limitations apply as much, if not more, to WEEE as to
other plastics waste streams.
Mechanical recycling of older WEEE which contains
plastics can cause a specific problem. Without strict
temperature control during extrusion there is a potential
risk of generating dioxins and furans from some
halogenated flame-retardants.
The extent of these problems differs significantly
depending on the availability of suitable treatment facilities
and of end markets for recycled products. An approach
which achieves optimum results is Integrated Waste
Management (IWM). (In the industrial setting described in
this report, the term Integrated Resource Management
(IRM) is similarly appropriate.) IWM uses a combination
of different recovery methods such as mechanical
recycling, feedstock recycling and energy recovery.
Decisions on which methods to use and in which
proportions need to be made locally, based on a detailed
knowledge of all the relevant factors.
1.3 Non-ferrous metals industry issues
The raw materials used by the smelting industry have
traditionally been of two main types, concentrated and
separated ores, and secondary raw materials or scrap. Scrap
has been traded worldwide for many decades. Its
INTRODUCTION
processing provides a combination of environmental and
economic benefits. For example, only one-sixth of the
energy is needed to produce copper from recycled material
than from ores.
Because of the large range and quantities of non-ferrous
metals present in scrap, this waste stream is an attractive
source of secondary raw materials. A correspondingly
wide range of processes is needed to recover all of the
metal values present. The metals refining industry, which
has long experience of recycling and recovery, is
characterised by a small number of producers who
between them make use of a wide range of technologies.
Figure 1 depicts the various streams involved in the
recycling of metals.
The “Metallurgical Network” in Figure 1 consists of a
number of companies engaged in smelting and refining
which trade with each other in an effort to make optimal
use of their capacities and specialised processes. This
inter-company movement of intermediate process streams
ensures that maximum recovery rates are achieved over a
very wide range of metals.
A third type of feed stream, WEEE, is becoming of
increasing interest to the non-ferrous metals industry. It
contains metals that are capable of extraction, and the
plastics content can play important roles in the smelting
process.
As with plastics recycling there can be potential concerns
about emissions when WEEE is recycled. However,
Boliden Minerals already have considerable experience of
recycling a range of E+E components, in particular printed
circuit boards and all types of cable.
1.4 Programme objectives
Key objectives of this programme were:
• Evaluate optimum methods of recycling waste E+E
material
Plastics Recovery from Waste Electrical & Electronic Equipment in Non-Ferrous Metal Processes.
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INTRODUCTION
T E C H N I C A L R E P O R T
Collect& Sort
ComponentProduction
MetallurgicalNetwork
Components
Assemblies
E+E Products
FeAlCuMg
PbSnZnNi
AuAgPdCd
SbInSeTe
Smelter
H2SO4 Glassy Slag (blasting, road construction)SiO2 Al2O 3 FeO CaO MgO
By-Products
Deposits Hg AsY Ga BrSc Ta ClAm Cd IHg
FIGURE 1: RECYCLING OF METALS FROM WEEE
• Understand the role played by the plastics content of
WEEE during the smelting process
• Understand what types of E+E equipment are suitable
for recycling or recovery
• Develop experience to ensure compliance with the draft
EC directive on waste E+E equipment
• Investigate concerns about the generation of dioxins and
furans from waste/scrap materials when recycling
end-of-life E+E equipment
• Establish additional uses for incremental capacity in the
Boliden smelter
Several trials in Boliden’s Rönnskär smelter were
conducted over a four year period (1995 - 1999), with
additional funding support from APME and the American
Plastics Council (APC).
2. WEEE CHARACTERISTICS
2.1 Electrical and Electronic (E+E) Waste
The amount of waste electrical and electronic equipment
(WEEE) generated in Western Europe has been
researched by SOFRES for APME in several studies. The
total of WEEE for 1998 from all E+E sectors is estimated
at 5.9 million tons. The E+E sectors of interest for the
recovery of non-ferrous metals are shown in Figure 2.
The dark coloured portion of the bars indicates the plastics
content for each of the E+E sectors shown.
More detailed characteristics of E+E waste streams have
been described in an earlier APME report (4).
Typical metals contents of four E+E waste streams are
shown in Table 1. The principal metal present in these
streams is copper, so for purposes of comparison, the levels
of high-value metals present in a typical copper ore are also
shown. The comparison highlights the importance of
maximising the recycling of WEEE, a process which is
facilitated by the presence of plastics in the waste streams.
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WEEE CHARACTERISTICS
FIGURE 2: E+E WASTE SECTORS SHOWING PLASTICS CONTENT
0 5 10 15 20 25 30 35 40 45
Telecommunications
Office Equipment
Data Processing
Equipment
Brown Goods
Cables
Other Materials
Plastics Content
% of total E+E waste
TABLE 1: TYPICAL METAL COMPOSITIONAL
ANALYSIS OF FOUR E+E WASTE STREAMS
Measured levels of all of these noble and heavy metals can
vary significantly depending on the source, age and
pre-treatment of the waste E+E equipment.
While the total quantity of E+E waste has increased in
recent decades, its percentage of recoverable metals
content has decreased. Some sectors, e.g. brown goods,
are now of questionable value in terms of recovery because
of their low non-ferrous metal content. However, when
used in non-ferrous metal recycling, the plastics content
has value, either as a chemical feedstock to replace the
reducing agents CO and H2, or as fuel. This value of the
plastics content can play a factor in decisions about the
management of E+E waste streams and good scientific data
are required to facilitate this.
The types of feed stream supplied to the various metal
recovery processes depend to a great extent on the supply
and demand situation of the secondary materials. The
amount of secondary materials replacing primary metal ore
concentrates ranges from as high as 50% down to 5-10%
depending on market prices.
2.2 Feed supplied to non-ferrous metal recycling
plants
Non-ferrous metals feed streams have traditionally been of
two main types: a) separated and concentrated ores and b)
secondary raw materials or scrap. Depending on the
process being used, the types of secondary feed used range
quite broadly. Examples of traditional sources of secondary
raw materials for the production of copper, lead, zinc and
precious metals are shown in Table 2.
TABLE 2. SOURCES OF SECONDARY RAW
MATERIALS
There is a complex global market in these secondary
materials which are traded in large quantities. For example,
the globally traded quantity of used printed circuit boards
having a high precious metal content is estimated to be
100,000 tons annually. The amount of cable scrap
recovered in Europe in 1998 is estimated to be in the
range 500,000 - 900,000 tons. The global figure is
approximately 2 million tons (5). Another significant
recycle stream is data processing and telecommunications
equipment with a quantity estimated at between 30,000
tons and 90,000 tons in 1998. Precise data on these
quantities of waste is not available and estimates are
dependent on a number of assumptions.
2.3 WEEE as a secondary raw material
WEEE has become of interest as a new source of
secondary raw material because of its recoverable metals
content and the availability of capacity in the smelting
industry to process it. From a broader systems perspective,
the economics of using these materials can be favourable in
view of the metal values recovered and the avoidance of
landfill and incineration charges. Avoidance of landfill
meets the requirements of the EC draft WEEE directive.
However, other environmental criteria must be satisfied
and one purpose of the work described here was to
investigate this aspect.
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WEEE CHARACTERISTICS
T E C H N I C A L R E P O R T
Copper (Cu) Lead (Pb) Zinc (Zn) Precious MetalsCopper wire scrap Used batteries Zinc ashes/brass Printed circuitElectrical switchgear Solder residue boardsPrinted circuit Cathode ray tubes EAF dust from steel Catalystsboards (Pb glass) mills JewelleryMachine shop Cable shielding Galvanising sludges Photographic filmproduction waste Dross
Keyboards Personal Printed Car Typical Computers Circuit Electronics Copper
Boards OreHigh Value Extractable MetalsAg (%) 0.05 0.009 0.3 0.12 0.00034Au (%) 0.005 0.001 0.008 0.007 0.00001Cu (%) 13 7 25 20 0.8Zn (%) 3 1.2 1.5 1 0.12Pd (%) 0.0020 0.0004 - - 0.04AlTOT (%) 18 11 3 - -Medium - Low Value Extractable MetalsNi (%) 0.6 0.2 0.5 0.3 -Pb (%) 0.3 1.5 - 1 -Metals processed in other facilitiesBi (%) <0.0003 <0.0004 0.17 0.01 -Fe (%)1 3 <0.1 5 5 -Sb (%) 0.3 0.5 0.06 0.08 -
1 Fe remaining after magnetic separation
3. NON-FERROUS METALSPRODUCTION
Non-ferrous metal production sites have highly integrated
plants making them very energy and resource efficient.
Most non-ferrous smelters are large-scale plants operated
by multinational companies such as Boliden Minerals
(Sweden), Norddeutsche Affinerie (Germany), Union
Minière (Belgium), Noranda (Canada) and Outokumpu
(Finland). A typical example, shown in Figure 3, is the
layout of the Rönnskär site of Boliden Minerals AB.
This report assesses the opportunities to use PC wasteadded to the feed stream of the Zinc Fuming Furnace andin a current routine process in which waste printed circuitboards are recovered in the Kaldo furnace. The design andoperation of these two furnaces is described below.
3.1 Zinc Fuming Furnace
Total annual Zinc production in Europe in 1999 was
approximately 2.7 Million tons. Of this total,
approximately 30% is generated from recycled raw
materials. The potential treatment capacity is significantly
higher.
Zinc production in Europe uses the following process
technologies:
Primary Zinc Production
1) Roasting of sulphidic concentrates followed by
hydrometallurgy, leaching the resulting calcine, purifying
the leach liquor and electrowinning zinc.
2) Sintering of sulphidic concentrates, smelting the sinter,
separation at high temperature of lead, liquid slag and
gaseous zinc, refining the zinc by distillation. This process
is known as the Imperial Smelting Process (ISP).
Secondary Zinc Production
3) Recovery of zinc from secondary sources via the
production of zinc oxide, to be supplied to either of the
above processes.
A major secondary source is steel-making dusts which arise
during re-melting e.g. of galvanised car scrap. The dust
may contain impurities. This upgrading is carried out in
rotary furnaces, e.g.Waelz kilns, or in fuming furnaces.
Technologies of types 2 and 3 are also referred to as
pyrometallurgy. The technology applied during this
investigation was No.3. The flow sheet of the Rönnskär
site (Fig. 3) illustrates the many options for entering feed
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NON-FERROUS METALS
PRODUCTION
SO2 plant
Roasting
Drying
Zinc Fuming
Refining
Precious Metals Plant
H2SO4 plantCopper production
OreConcentrate
.
SecondaryCopper RawMaterials
Smelting Converting Refining Copper
Gas cleaning
LiquidSulphurDioxide
SulphuricAcid
Lead productionElectronic Scrap
Lead Concentrates
NiSO4 plant
Lead
Zinc clinker
Scrap
PalladiumGoldSilver Slime
Selenium Crude Nickel Sulphate
KaldoFurnace
Slag
FIGURE 3: TYPICAL NON-FERROUS METAL REFINING PLANT
materials to non-ferrous smelters. In this study, the zinc
fuming process was chosen for PC waste because it uses
fossil fuel both as a reducing agent and as fuel to recover
zinc from slags.
A fuming plant consists of three separate processes:
1) Fuming furnace
2) Settling furnace
3) Clinker furnace
These are shown in detail in Figure 4.
The fuming furnace is a water-cooled rectangular furnace.
Water cooling is used to generate an autogenous lining of
frozen slag. This prevents attack of the steel shell by the
corrosive liquid slag. The heat is recovered in the boiler.
Hot cooling water from the heat exchangers is fed into the
Skelleftehamn district-heating network connected to the
Rönnskär Smelter. The heat from the off gases is
recovered in the boiler.
Finely ground coal and preheated air is injected into the
liquid slag through submerged injection pipes (tuyeres)
situated along both long walls of the furnace. The injected
coal and air react immediately to form CO gas which
reduces metal oxides such as magnetite (Fe3O4), lead
oxide, and zinc oxide in the slag. Some of the useful resul-
ting metals are in the vapour state, which enables them to
be stripped from the liquid slag. Nitrogen contained in the
injected air assists the stripping of zinc vapour from the
slag.
Directly above the foaming bath of liquid slag, the zinc
vapour is re-oxidised to zinc oxide. The reduction process
also recovers other metals such as lead and arsenic, and in
addition extracts halogens from the slag. The resulting
mixture of oxides (“mischoxide”) is de-halogenated in the
clinker furnace.
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NON-FERROUS METALS
PRODUCTION
T E C H N I C A L R E P O R T
ESP
1 2 3 4 56Storage
Raw FumeHopper
FluorineScrubber
Gas Cooler
Bag House
Ball Mill
103
Rotary Cooler
Clinker Furnace
Cyclone
To WasteWater Plant
Clinker
Granulated Slag
Waste Heat Boiler Economizer
Cooling Tower
Emission Check Points
Mixed oxide to Clinker Plant
Speiss/Matte
Crusher
Ash HopperTransfer of Slag
Revert SlagPCs
EAF dust
Settling
Furnace
Oil +Air
Coal
SlagFumingFurnace
Sampling Points
Lead
Bearing
Dust
Material Hoppers
FIGURE 4: ZINC FUMING PLANT
The cleaned slag is tapped from the fuming furnace into
the settler furnace. Here the remaining copper alloy
droplets and copper sulphide droplets in the liquid slag are
separated into liquid phases. These contain copper and
other precious metals and are either recycled to the copper
smelter or sold for further treatment in specialised
metallurgical plants belonging to the “Metallurgical
Network” highlighted in Figure 1. These two phases, rich
in copper and precious metals, allow for the almost
complete recovery of copper and precious metals
contained in the PC waste added to the furnace.
The geometry and operating parameters of the zinc
fuming plant can be seen in Table 3.
TABLE 3: OPERATING PARAMETERS OF
THE ZINC FUMING PLANT
The total feed to the Zinc Fuming Furnace consists of:
1.Liquid iron-silicate slag from the electric copper
smelting furnace
2.Recycled reverts (solidified slag) e.g. from the transfer of
the liquid iron-silicate slag (No. 1 above) by ladle
3.Internally recycled dust from the fuming furnace (ash
hopper - see Figure 4)
4.Steel making dust (EAF dust) from electric arc furnaces
re-melting galvanised steel scrap
5.E+E waste used for the test campaign
Table 4 indicates the products and their quantities
produced by the zinc fuming plant.
TABLE 4: PRODUCTS FROM THE ZINC FUMING
PLANT
3.2. Kaldo Furnace
There are several similarities in the manufacturing
technologies used to recover non-ferrous metals in the
zinc fuming furnace and the Kaldo furnace. Plastics are
used as fuel, easily oxidisable impurities are dissolved in a
liquid slag and precious and base metals are collected as an
alloy or “Matte” (liquid sulphides). Both processes make
use of the other plants on the site to extract the metals.
Residue streams, such as slags, dusts, sludges or matte, are
usually recycled on-site or processed at other companies,
making use of metallurgical networks (Fig. 1) when
in-house processing capacity is unavailable or trading is
economically more attractive. Through this highly
integrated industry set-up, which avoids the need for
landfilling, the non-ferrous metals industry contributes to
sustainable development by assuring ecologically sound
and economically viable treatment of the residues.
The Kaldo furnace has been specially developed for the
recovery of metals from secondary raw materials. The total
amount of secondary raw materials and lead concentrate
currently processed by Boliden’s Kaldo furnace is
approximately 100,000 tons per year. Most of the
large-scale plants at other major companies such as
Norddeutsche Affinerie (Germany), Union Minière
(Belgium) and Noranda (Canada) have similar capacities.
Kaldo technology has been practised for over 15 years to
recover cable scrap and printed circuit boards. Sound
ecological treatment is assured by means of stringent
emission regulations.
The process is illustrated in Figure 5 on the next page.
9
NON-FERROUS METALS
PRODUCTION
Length 8.1 m District heating: 4-8 MWWidth 2.4 m Capacity: 105 t (batch)Nozzles: 52 Fuming agent: Coal + preheated airFuming cycle: 120 min Coal consumption: 1.5 kg/t ZnOff gas volume: 140-170,000 m3/h Steam generation: 55 tph (40 bar)
Tons per day Zn (%) Pb (%) As (%) Se (%) Cu (%)Mixed Oxides: 120 65 10 0.15 0.02 0.2Slag: 750 1 0.02 <0.005 <0.002 0.5Clinker: 110 75 5 0.01 - 0.1
The analysed material is blended in heaps to improve
integration with the melt and allow for maximum use of
energy and smelting capacities. The material is charged by
front-end loader into a skip hoist. The hoists are emptied
from above under a ventilated cover into the furnace
vessel. The furnace is then tilted back into the operating
position. Oxygen supply to the furnace via a lance is
started. If necessary, an oil-oxygen burner assists in
reaching the ignition temperature. Combustibles
contained in the charge supply heat for melting of the
printed circuit board scrap, additional scrap and fluxes (slag
formers). Off-gases from the furnace are collected in a
water-cooled hood, where additional post-combustion air
also enters. Post-combustion takes place at around
1200°C. Residence time is estimated to exceed 2 seconds.
Steam is produced in the hood and the offtake and is fed
into the smelter’s steam network for in-process use and
energy recovery. The process gases are then shock-cooled
in a venturi scrubber, the dust particle loaded water being
settled in a settler. Water is bled to the central water
treatment plant for metal sulphide precipitation and lime
treatment. The sludge from the scrubber, and also the
sulphide precipitate from the water treatment plant, are re-
circulated to the copper smelter to increase raw material
recovery.
The process produces a metallic copper alloy that is
transferred as liquid to the copper smelter for recovery of
metals (Cu, Au, Ag, Pd, Ni, Se, Zn). Dusts (containing Pb,
Sb, In, Cd) are also generated and these are processed at
other smelters. Slag arising in the process is sent to the
Boliden concentrator for extraction of any remaining
metal value.
The role of plastics from cable insulation is to supply
process heat for the smelting operation. PVC and
crosslinked low-density polyethylene in the cable scrap, as
well as the thermosetting resin in the printed circuit
boards, perform this very valuable function in the Cu
recovery process. Their high heat value provides most of
the process heat needed for secondary raw material
smelting to produce prime grade copper.
Plastics Recovery from Waste Electrical & Electronic Equipment in Non-Ferrous Metal Processes.
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NON-FERROUS METALS
PRODUCTION
T E C H N I C A L R E P O R T
Oxygen
Feed
Furnace Position 2 - Smelting
Furnace Position 1 - Charging
Process encapsulation
connected to bag house
Process gas duct
to venturi scrubber
Furnace Position 3 - Tapping
Oil
FIGURE 5: THE KALDO FURNACE
4. INTEGRATED WASTE MANAGEMENT(IWM) OF WEEE
Integrated Waste Management is a subject which is
discussed widely both in society in general and in the
development of European and national legislation. Within
the EU, several initiatives to describe the system in more
detail exist such as (8). A proposed schematic overview of
IWM, based on the one in Reference 8 (page 20), is
shown in Figure 6.
4.1 WEEE pre-treatment
Waste electrical and electronic equipment is normally
collected through waste management companies or
communities or taken back by the original equipment
manufacturer as outlined in Figure 6. There are no
European (CEN) standards in existence at the time of
writing on important operations such as inspection,
dismantling and sorting of WEEE. The important aspects
are dismantling, removal of valuable parts like printed
circuit boards and removal of hazardous components such
as old Hg switches and NiCd batteries. These steps need
to become standardised operations in any type of WEEE
handling. For most of the articles or equipment the degree
of dismantling needs to be evaluated further. Dismantling
adds significantly to the total cost of treatment and some of
the products generated, such as old housings, have no
material value.
The use of secondary metals in the non-ferrous metals
industry requires all companies either to have shredding
capabilities on site or to receive shredded materials. Partial
dismantling has to be done at the recycling/recovery
operation site to remove parts containing hazardous
elements like Hg-containing batteries, relays etc.
4.2 WEEE feed preparation for the trial
For this test campaign, the PC scrap was collected from
various sources within Scandinavia. Transportation was
mainly by train. The collected scrap was first inspected by
the company Arv. Andersson at its scrap yard in Skellefteå
for the occurrence of known Hg-containing pieces. These
would have to be removed. Figure 7 provides a typical
picture of the PC waste material quality as received.
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INTEGRATED WASTE
MANAGEMENT (IWM)
OF WEEE
MARKET
(Original use)
E+E
Product
Product to market
Product
Performance
Secondary UseRe-use
MARKET
(Other use)
END-USE-ENERGY
MARKET
SAFE FINAL DISPOSAL
PROCESS
PROCESS
INSPECTION
and eventual
SORTING
Waste from recovery
Waste for disposal
Reject
Open loop
Sorting Residue
RECOVERY
ÒPrevention by source reductionÓ
Closed LoopMaterial for recovery
Waste
FIGURE 6: INTEGRATED WASTE MANAGEMENT (IWM)
A hammer mill shredder with a magnetic iron separator
was used to prepare the bulky material. The plant is
equipped with an automatic sampler to take online
material samples for analysis. After sampling of about
5-10% of the feed, the bulk of the WEEE material was
transferred to the Rönnskär smelter.
No major problems were experienced during crushing and
fragmentation although some printer rolls were hard to
crush. The temperature increase during mechanical
treatment was not greater than that experienced during the
routine treatment of scrap at Rönnskär. The working
environment was checked for heavy metals and dioxins.
All the values were below actual or recommended
hygienic limit values in Sweden.
The fragmented PC scrap was then mixed by front-end
loader with crushed revert slag in a 50:50 mixture. The
proportions were chosen to optimise bulk handling and
silo feeding and avoid any blockages during feeding.
Problems were experienced if insufficient care was taken
to ensure that the material was fragmented into pieces
smaller than ca 30 mm. Especially noticed was the
formation of copper-wire agglomerates and printer
ribbons, which could cause problems during feeding from
the silo.
5. TRIALS WITH WEEE: PCs
Boliden’s technical capability to take the entire shredded
PC scrap into their zinc fuming plant without extensive
dismantling was one of the incentives to start this
programme. Selected removal of critical components
which contain Hg will keep the total chain cost low by
avoiding high pre-treatment costs for material recovery.
5.1 Recycling of PC scrap in the zinc fuming furnace
So far, five campaigns have been run with the aim of
thoroughly exploring the metallurgical, environmental and
economic impacts of this new type of E+E feed. The
testing programme consisted of four major series, outlined
in Table 5.
TABLE 5: TESTING PROGRAMME TRIAL SEQUENCE
The PC feed streams used in these tests arrived from
various sources within Scandinavia and were sampled
according to type, (PC consoles, keyboards and monitors)
for chemical analysis.
TABLE 6: TYPE AND ORIGIN OF FEED STREAMS
The mix containing the PC scrap was transferred by
on-site dumper trucks to the conveyor belt feeder and on
to the silos on top of the zinc fuming furnace. The PC
scrap/slag mixture and pelletised steelmaking dust were
drawn from the two silos and fed by belt conveyor onto
the chute to the fuming furnace. The feeding belts are
equipped with belt weighing devices.
Table 7 gives details of the experimental plan for Test
Series II to IV.The normal charging practice was applied
except for one trial, Trial D. In normal charging, the cold
material is charged during the early part of the fuming
cycle. In Trial D charging was prolonged throughout the
Plastics Recovery from Waste Electrical & Electronic Equipment in Non-Ferrous Metal Processes.
12
TRIALS WITH WEEE: PCs
T E C H N I C A L R E P O R T
FIGURE 7: PC MATERIALS AS RECEIVED
Test Series Added to the feed stream TimingI Steel dust and PC scrap 1995II Steel dust and PC scrap April 1996III PC scrap only October 1996IV Steel dust only 1999
Year Country PC Consoles Keyboards & Monitors Age1995 Sweden 12 t 7 t 1980-19911996 Sweden /Norway 53 t 17 t 1980-1990
fuming cycle in order to understand the effect of different
feeding modes.
TABLE 7: EXPERIMENTAL PLAN FOR
PC RECOVERY IN ZINC FUMING PLANT
DURING SERIES II TO IV
In addition to the analysis for metals, heavy metals and
precious metals shown in Table 1 (page 6), an extended
analysis was also performed during two of the above trials,
B and C. The results are shown in Tables 8 and 9.
TABLE 8: FEED STREAM ANALYSIS‡
TABLE 9. METALS ANALYSIS OF PC PARTS
Analysis was carried out for halogen-containing organic
compounds: chlorinated PCDD/Fs, brominated
PBDD/Fs and mixed brominated and chlorinated
PBCDD/Fs. The values found varied quite significantly.
No correlation between the amount of PXDD/Fs and
their source or age has so far been identified. The average
PXDD/Fs content of all the samples of waste E+E plastics
so far investigated by APME have met the following two
German regulations: “German Regulations for Hazardous
Materials” (6) and “The German Chemical Banning
Ordinance” (7). A potentially high content of these
organic compounds may well provide an extra reason for
large-scale handling, automatic fragmentation, Syngas
production and post-combustion, thus minimising the
impact on the internal and external environment.
Furthermore, potentially significant amounts of these
impurities suggest that mechanical recycling of old plastics
from the WEEE should be looked at with great care. The
process shown in Figure 4 has proven to be a sink for
dioxins and halogenated organic compounds, as
demonstrated in section 6.5.
The operators used their normal process mode to carry out
feeding to the furnace. The fuming process did not deviate
from its usual performance. Operating capacity was limited
during one of the campaigns by the capacity of the
subsequent process. When feeding large amounts of PC
scrap, limitations in boiler capacity were experienced. In
these cases the coal feed rate was reduced significantly
while charging the PC scrap/slag mix, indicating a
substantial substitution of coal by plastics.
5.2 Printed circuit board and cable scrap recovery at
the Kaldo furnace
Processing of WEEE has been carried out in the Kaldo
furnace for many years and is a regular commercial
operation, conducted in campaigns between lead flash
smelting campaigns. Similar plants are used for autogenous
smelting of lead concentrates. The length of the
campaigns, and hence the total annual capacity available
for WEEE, is thus determined mainly on economic
considerations. Currently the split is about 50% of the
available time running on lead and WEEE respectively.
The Kaldo plant also makes use of an existing lead kettle
for the recovery of metals from lead sheeted complex
13
TRIALS WITH WEEE: PCs
Trial A B C D EYear 1996 1996 1996 1996 1999Type Base Medium High Prolonged BaseFeed slag (t) 85 85 85 85 85WEEE (t) none 10 20 20 noneEAF dust (t) 5 5 5 5 15
Organic Compounds Trial B Trial CAsh (%) 9.2 7.2Hu (MJ/kg) 31.2 24.4C (%) 65.4 62.7H (%) 6.5 6.5O (%) 12.0 14.1S (%) 0.2 0.2
Metals Trial B Trial CCd (mg/kg) 99 24Tl (mg/kg) <1 <1Hg (mg/kg) 9.5 0.9Sb (mg/kg) 120 63As (mg/kg) 2 <1Pb (mg/kg) 250 280Cr (mg/kg) 41 13Co (mg/kg) 1 1Cu (mg/kg) 200 340Mn (mg/kg) 94 94Ni (mg/kg) 250 58V (mg/kg) <2 <2Sn (mg/kg) 630 5,400Zn (mg/kg) 1,800 1,500
cables. Lead is melted off under hood coverage. The
remaining copper and iron fraction is sent to the copper
smelter. The off-gases from this treatment are ducted to
the gas cleaning devices described earlier.
No specific emission measurements suitable for inclusion
in the report were carried out. The emission levels from
this plant, viewed on an annual basis and shown in
Table 10, are taken from Boliden’s environmental report.
They are based on a total scrap operating time of
3855 hours.
TABLE 10: EMISSIONS FROM THE KALDO
FURNACE (1998)
6. RESULTS
6.1 Metals Recovery
Typical recovery rates exceed 95% of the metal in the feed
stream. Consequently, where spare smelting capacity is
available to process them, feed streams other than those
traditionally used, such as WEEE, are becoming of interest
to the smelting industry. The recovered metals, i.e.
copper, nickel and precious metals, cannot be
distinguished from metals extracted from primary ores.
In addition to the metal values recovered, processing of
these streams provides a significant environmental benefit.
6.2 Coal Substitution: Energy balance for the Zinc
Fuming process
The influence of plastics on the heat balance is best
analysed by means of a comparison with normal operations
(Figure 8). The data show, as does the experience of the
operators, that carbon and hydrogen from the plastics
substituted carbon and hydrogen normally provided by the
coal. By comparing the fuming speed, the generation of
steam, and the specific energy, we conclude that for the
most part the plastics content was used for chemical
purposes.
Plastics Recovery from Waste Electrical & Electronic Equipment in Non-Ferrous Metal Processes.
14
RESULTS
T E C H N I C A L R E P O R T
Dust Cu Pb Zn Cd As Hg SO2 F Cl PCDD/Ftpa tpa tpa tpa tpa tpa tpa tpa tpa tpa gpa Eadon1.78 0.03 0.828 0.11 0.002 0.004 0.004 9 0.034 4.24 0.084
In Out In Out
0%
20%
40%
60%
80%
100%
Coal
WEEE
In
Fume Gas
Cold Material (25 12000C)
Heat Losses
Chemical (Zn reduction)
Air
Out
FIGURE 8: INFLUENCE OF PLASTICS ON THE ENERGY BALANCE
IN THE FURNACE SEGMENT
The effects on batches with PC scrap are well within the
normal operational parameters with regard to fuming
speed, despite a lowered coal feed rate of 1 ton per hour.
The batches with PC scrap have an apparent lower unit
coal consumption per ton of zinc. From this we conclude
that the plastics take part in the reduction of zinc oxide
from the slag. The exact quantity is difficult to define at
low substitution rates.
The left side of Figure 9 illustrates the progressive
reduction in coal usage resulting from Boliden’s efforts to
improve the operational efficiency of the Zinc furnace.
Each data point represents the average coal consumption
rate for one month during a 3-year period.
The section of the graph to the right of the dotted line
shows the individual batch data during the conduct of Test
Series II in April 1996.
It may be possible to detect a positive influence on process
kinetics through early reduction of magnetite by plastics
and the remaining aluminium in the WEEE. According to
the chemical stoichiometry, 1 kg of Al reduces 25 kg of
Fe3O4 and 1 kg of plastic reduces approximately 50 kg of
Fe3O4. Reports in the literature mention a strong positive
influence of H2 on reduction kinetics, compared with CO.
To completely reduce all magnetite in the charge, an
estimated 300-400 kg of Al or 200 kg of plastic would be
required. When aluminium is used, the resulting increase
in the aluminium content of the final slag would be
0.7 - 0.9%, which in some cases may well lead to process
problems.
6.3 Metallurgical aspects: Zn product quality
Zinc fuming rates during the trials were well within the
normal band of operation, in spite of a reduced coal feed
rate. Figures 8 and 9 illustrate the performance of the trial
runs with regard to key parameters. From this we
conclude that a major part of the hydrocarbons contained
in the plastic was used as a reducing agent, i.e. taking part
in the chemical reaction. The standard chemistry
describing this would be a formation reaction of hydrogen
and carbon monoxide from the plastic, which then act as
reducing agents to form zinc metal in the melt.
Once this gaseous zinc leaves the molten bath
it is oxidised to zinc oxide and is recoverable in
the electrostatic precipitator (ESP).
The composition of the product was
continuously monitored and fell well within
the normal range. No deviation in major
elements such as Zn, Pb, Sn, F and Cl, could
be detected. The increased load of halogenides,
especially bromides, could be traced to the
intermediate product called mixed oxides. The
subsequent process of halogen removal in the
clinker furnace has by now adjusted its practice to
accommodate the increased load of halogens introduced
by steel making dust and other feed streams. Halogen
removal is carried out in a long rotary kiln by re-heating
the raw fume together with coke additions to
approximately 1200°C. The rotary kiln can be seen in
Figure 4 (page 8), described as "Clinker Furnace". By
means of this process, halogenides, together with part of
the lead, are separated into a dust which is sent for
processing at a zinc smelter. The clean zinc oxide "clinker"
is processed at Boliden’s 50% owned Norzink plant in
Norway.
The finished product zinc produced in Norway has been
checked for the occurrence of dioxins. The results show
values below detection limits and no influence on levels of
critical impurities such as halogenides could be detected.
15
RESULTS
1
1.2
1.4
1.6
1.8
2
2.2
2.4
2.6
2.8
3
Jan
1993
May Sep Jan
1994
May Sep Jan
1995
May Sep Jan
1996
5 10 15
Batch Number
Tonsofcoalpertonofzincfumed
Monthly averages before the trialsIndividual batch data
during the trial period
FIGURE 9: MONTHLY AVERAGE COAL
CONSUMPTION RATE
6.4 Emissions, Material and Micro-Organic Balances
It is difficult to match mass and component balances on an
industrial scale for elements at very low concentrations
such as the volatile metals and halogens or for
micro-organic components. The major uncertainties are
not with the analytical determination of concentrations
but rather with the difficulty of obtaining reliable
representative samples and making consistent mass flow
measurements. Additional problems arise from a
combination of sampling errors, analytical difficulties and
errors, scarcity of costly assays, and errors in determining
solid and gas flows. The material flow during the fuming
tests was calculated for each batch and is illustrated in
Figure 10, which contains typical compositions of the
different streams around the fuming process. The
important elements, Hg, Br, Cl, F and Sb, were balanced.
Using this elemental analysis, data covering the entire
process, including the input and final output, can be
calculated.
In summary, less than 3% of the halogen content is emitted
through the stack of the zinc refining plant in Norway.
The total halogen content is liberated in the fuming plant
and is neutralised in the gas cleaning section. Metal
sulphide precipitates from the waste water plant are
re-circulated to the copper smelter. After final polishing by
lime precipitation, where fluorine is also precipitated
(as NaF and CaF2), other salts (NaCl, CaCl2, NaBr and
CaBr2 ) are discharged to the sea (Gulf of Bothnia). Of the
antimony added with the WEEE to the fuming process,
over 65% leaves the plant with the raw fume. The overall
potential recovery of Sb is about 40% under these
conditions. The rest is stabilised in a glassy slag or
contained in jarosite in mountain caverns. For mercury the
corresponding figure was approximately 22%, but there
was no special gas cleaning during the trial.
The results of this study suggest that the following
measures should be implemented to deal with WEEE
which contains potentially high amounts of Hg:
• Tighter incoming WEEE control for Hg at the site and
• Establishment of specifications which ensure low Hg
levels or
• Investment in effluent gas treatment (e.g. AC filter)
6.5 Destruction efficiency
One of the objectives of this test programme is to support
the general WEEE waste management strategy and to
show that plastics are recyclable in the form of feedstock.
This has been the subject of many reviews and research
studies because of the potential content of micro organic
Plastics Recovery from Waste Electrical & Electronic Equipment in Non-Ferrous Metal Processes.
16
RESULTS
T E C H N I C A L R E P O R T
Fuming
Furnace
Hg
(g)
Br
(Kg)
Cl
(Kg)
F
(Kg)
Sb
(Kg)
70 <2.5 15 1.8 8.3
EAF Dust 20 <2.5 95 0.4
Crushed Slag <5 <2.5 <5 2.5
Hg
(g)
Br
(Kg)
Cl
(Kg)
F
(Kg)
Sb
(Kg)
Slag <80 <40 <80 40 40
Hg
(g)
Br
(Kg)
Cl
(Kg)
F
(Kg)
Sb
(Kg)
Cleaned Slag <80 <40 <80 40 40
Hg
(g)
Br
(Kg)
Cl
(Kg)
F
(Kg)
Sb
(Kg)
Raw fume to Boiler,
Condensation Tower and ESP 70 <2.5 15 1.8 8.3
Hg
(g)
Br
(Kg)
Cl
(Kg)
F
(Kg)
Sb
(Kg)Raw Fume to
the Stack17 0.8 0.6 0.6 0.5
Hg
(g)
Br
(Kg)
Cl
(Kg)
F
(Kg)
Sb
(Kg)
Stack total out 22 3.2 0.9 1.3 0.01
Raw Fume total 24 81 81 73 66
WEEE
FIGURE 10: MATERIAL FLOW AT THE FUMING PLANT
halogenated substances, such as halogenated di-benzo
furans and dioxins (PXDD/Fs) in WEEE. Mechanical
recycling of WEEE with increased detectable levels of
PXDD/Fs will give rise to potential costs of handling and
exposure to recyclates made from these WEEE plastics.
The feedstock recycling technology as shown in this report
will not lead to these kinds of potential risk, if it can be
proven that no equivalent exposure to operators during
feedstock recycling takes place. Equally important is the
fact that the overall destruction efficiency of the process is
guaranteed at a high enough level. Because of this
important issue, dioxin and furan balances have been
carried out and the results of two calculations are shown
here.
In the case of Boliden, the co-treatment of waste PC
equipment and steel dust makes it important to understand
the respective potential contribution of these two
materials. The following short analysis (Figure 11) is based
on the total amount of polyhalogenated dioxins and furans.
FIGURE 11: DIOXIN AND FURAN MASS BALANCE
FOR THE ZINC FUMING PLANT
A more detailed analysis (see Figure 12) has been done for
the critical and regulated 2378 congeners of PXDD/F
which are part of the existing legislation in Germany on
emissions from waste incinerators.
The total halogenated dioxin/furan mass balance shows a
clear destruction of all micro organic compounds from this
family with an efficiency of over 98%. From the total input
of 6.4 g per batch only 0.104 g per batch leaves the fuming
plant. This amount is almost evenly split between the
gaseous emissions and the amount staying with the raw
fume. Since the raw fume is treated a second time at high
temperature in the downstream kiln, which destroys
residual PXDD/Fs on the solid, the destruction efficiency
over both plants is more than 99%.
The method used to calculate the destruction efficiency is
based on a per-batch type of operation, as the long- and
short-term PXDD/F emission results are not very
different. From this it can be concluded that in
determining the dioxin balance, short-term sampling of
two hours for one batch is equally representative as
long-term sampling.
In Figure 12 the equivalent balance for the same batch
using toxic equivalent factors (ITE) is shown.
FIGURE 12: TOXIC EQUIVALENT (I-TE) MASS
BALANCE FOR THE ZINC FUMING PLANT
The ITE results indicate a good level of destruction
efficiency in the zinc fuming plant. An even higher overall
destruction efficiency is achieved because of the
subsequent clinkering process.
17
RESULTS
Input
Feed Quantity (tons) PXDD/F Concentration( g/kg)
Flux
(g/batch)
Slag
Steel Dust
Cold Slag
PC Scrap
86
5
5
5
0
30.6
0
1250
0.0
0.15
0.0
6.25
Total Input 6.4
Output
Quantity PXDD/F ConcentrationOutput
(m3/h) (tons) (mg/kg) ng/m
3Sampling
Time (h)
Flux
(g/batch)
Stack Gas
Raw Fume
130,000
8.48 6.68
182 2 0.047
0.057
Total Output 0.104
m
Input
Feed Quantity (tons) ITE Concentration (mg/kg) I-TE Flux
(g/batch)
Slag
Steel Dust
Cold Slag
PC Scrap
86
5
5
5
-
0.95
-
0.0171
0.0
0.00475
0.0
0.0000855
Total Input 0.00483
Output
Quantity ITE ConcentrationOutput
(m3/h) (tons) (mg/kg) ng/m
3Sampling
Time (h)
I-TE Flux
(g/batch)
Stack Gas
Raw Fume
130,000
8.48 0.078
2 2 0.00026
0.000561
Total Output 0.0008
7. ENVIRONMENTAL IMPACT
7.1 Emissions to air
Measurements of the environmental impact of this type of
feed have been carried out by both the Boliden
measurement team and by an independent certified
laboratory. The results from both laboratories agree within
satisfactory limits. The average emissions for the more
important compounds: CO, NOX, SO2, TOC and O2
were as follows:
TABLE 11. EMISSIONS DURING ZINC FUMING
TESTING
The emissions of other compounds are not shown as they
were not affected by the co-processing of PC scrap. The
concentrations of dust and ten heavy metals (sum of Sb,
As, Pb, Cr, Co, Cu, Mn, Ni, V, Sn) were <11 mg/m3 and
approximately 0.4 mg/m3 respectively.
7.2 Emissions to water
The run-off waters and the process water from the
subsequent scrubbing at the clinker plant, where the raw
fume is dehalogenated, are treated jointly with the waters
from the rest of the smelter site in a central water
treatment plant. Heavy metals are efficiently precipitated as
sulphides. The sulphide sludge is returned to the fluidised
bed roaster of the copper plant. The water is further
treated with lime to precipitate fluorine as fluorspar
(CaF2). After treatment, the cleaned water is discharged to
the sea (Gulf of Bothnia).
7.3 Disposal of solids
Deposits originating from the fuming treatment are minor
amounts of slag and lead. Minor slag volumes are used for
on-site construction and lead is concentrated into the
clinker dust which is shipped for recycling to other non-
ferrous metals producers.
The dusty materials are handled with care due to their
toxic nature and are kept well contained and sealed
according to Swedish government regulations. The Pb
bearing dust was checked for the occurrence of dioxins,
using a combination of three-monthly samples. These
samples represented normal operating practice with the
addition of EAF dust, but without the addition of PC
scrap.
From the balance of dioxins it may be concluded that
dioxins could occur in the lead bearing dust deposits, but
that their concentration is below the values of the German
Chemical Banning Ordinance. No indications are
available that these values are increased by the input of PC
scrap.
Insoluble elements or compounds at the zinc plant
(Norway) end up in the jarosite precipitate and are
disposed in dry mountain caverns. As indicated above, the
final product has been checked for the occurrence of
dioxins. The result shows values below detection limits.
7.4 Workplace safety
Workplace safety was investigated and analysed. The
potential impact on operators of dioxins/furans was
checked by means of a dust-emission sample. The value in
the fuming plant during recycling of PC scrap was found
to be 0.08-0.12 ng/m3, well below the recommended
50 ng TE Eadon /m3 (8 hours working hygienic value).
The potential impact of micro organic compounds during
feed preparation was further checked by personal
monitoring. The results from two different modes of
operation of the fragmentation plant show values below
the proposed German workplace standard. No special
precautions were taken during the handling of the PC
scrap. The level of heavy metals was found to be well
below the hygienic limit values. If necessary the practices
for handling this type of material could be tightened.
Plastics Recovery from Waste Electrical & Electronic Equipment in Non-Ferrous Metal Processes.
18
ENVIRONMENTAL IMPACT
T E C H N I C A L R E P O R T
CO NOX TOC SO2 O2
mg/m3 mg/m3 mg/m3 mg/m3 vol %A 10-15 100-160 2 600-1000 12-14B 10-15 160-180 1 945 10-13C 20-50 160-190 2 740 11-12
8. CONCLUSIONS
This successful example of PC co-treatment within the
standard operation of a zinc fuming furnace shows that
other opportunities may exist to use waste plastics as feed
stock or fuel in the non-ferrous metals industry.
The maximum amount tested was 10 t/charge,
corresponding to some 15,000 to 20,000 tonnes per year
of PC scrap. Preliminary tests with continuous feed
indicate no major differences compared with the batch
charging used for this trial. Continuous feed would allow
for approximately 15,000 t per annum of PC scrap to be
treated. The possible influence of an increased halogen
load on the corrosion of gas cleaning equipment must be
assessed in a long-term performance test.
The handling and fragmentation of WEEE falls well
within the broad range of materials already handled at the
Boliden Rönnskär smelting site. At the normal feed rates
studied, co-treatment of PC scrap did not harm the fuming
process. The heat released by the introduction of the
plastic contained in the scrap was compensated by a lower
feed rate of coal.
The influences on the environment are to be considered as
being positive ones, as the process essentially represents an
effective sink for dioxins and heavy metals. No significant
difference in emissions of heavy metals was detected,
except for mercury during the first test run. Several new
requirements, for example the setting of acceptance limits,
and plant improvements such as an active carbon filter for
effluent gas will ensure that the treatment of WEEE
containing potentially higher levels of Hg is dealt with in
an ecologically sound and responsible manner.
No significant increase in dioxin emissions for the trial
batches with PC scrap was detected. The patterns of the
dioxin congeners in the feed and in the stack samples differ
significantly, also stressing the efficient destruction of
micro-organic compounds sometimes contained at a very
low level in old E+E equipment. The exposure of the
employees to micro-organic compounds and toxic
elements does not exceed hygienic limit values. Standard
routines for personal hygiene should be enforced.
Material recycling, comprising mainly dismantling and
material separation, is not charged today at full cost, being
subsidised through cheap labour from the government or
the community. If the level charged for treatment of
WEEE was of the order of €350 to €800 per ton of scrap,
the method described in this report, using the zinc fuming
furnace, would be economic, requiring no further subsidy.
WEEE would be able to compete with other secondary
raw materials. This is due to low costs and high direct
recovery of heavy metals. The inherent extractable metal
content varies considerably within the wide groups
represented by WEEE and the treatment cost is hence
directly related to the market value of the extractable
metals.
19
CONCLUSIONS
9. RECOMMENDATIONS
Current proposals from national environmental protection
agencies call for dismantling of WEEE into separate
components to achieve better environmental performance.
The depth and extent of dismantling is sometimes very
vaguely defined and there is a great lack of sound data,
both socio-economic and scientific. The joint efforts at
Boliden have shown that total dismantling of PCs is not
required. A low content of potentially harmful chemical
elements in the feed, such as Hg or Cd, should be achieved
by selective dismantling. Investment in known and
demonstrated gas cleaning technology may be appropriate.
It is recommended that certain used E+E equipment,
which is known to contain substantial amounts of precious
metals and plastics, be handled in smelting processes of the
types described.
10. ACKNOWLEDGEMENTS
The authors would like to acknowledge the valuable
contribution to the success of their work made by a
number of individuals and organisations:
Project Sponsors
Boliden Minerals AB
Association of Plastics Manufacturers Europe (APME)
American Plastics Council (APC)
Companies
AB Arv. Andersson, Skellefteå, Sweden
Individuals
M.Fisher – American Plastics Council
APME E+E Sector Task Force
M. Frankenhaeuser - Borealis Polymers Oy
P.Peuch – BP/Amoco
Plastics Recovery from Waste Electrical & Electronic Equipment in Non-Ferrous Metal Processes.
20
RECOMMENDATIONS
T E C H N I C A L R E P O R T
11. REFERENCES AND WEBSITES
References:
(1) Lehner T. & Vikdahl A. (Boliden) “Trim, slim and
quality”. Paper presented at ‘Copper 95’,
Santiago de Chile, November 1995
(2) Willbrandt, P. “Operational Results of Norddeutsche
Affinerie Copper Smelter” in Queneau. P (Ed.)
‘Symposium: Extractive Metallurgy of Cu,Ni,Co’
Las Vegas, 1993.
(3) Moulins, L.J. & Picard, D. “Precious Metals Recycling
at Noranda Horne - a logical choice”. Paper presented
at ‘Precious Metals 1994’, Vancouver BC.
(4) Vehlow, J. & Mark, Frank E. “Electrical and
Electronic plastics waste co-combustion with
Municipal Solid Waste for energy recovery.” APME
Technical Report No. 8020, February 1997.
(5) Bureau of International Recycling (BIR) “Plastic
Coated Cable Scrap”. Article on website
http://www.bir.org/
(6) Hazardous Substances Ordinance: Gefahrstoffrecht,
Recht-und Verwaltungsvorschriften über gefaehrliche
Stoffe im Arbeits- und Vebraucherschutz, vom 26
Oktober 1993, zuletzt geändert 27 Januar 1999.
(7) Chemicals Banning Ordinance: Verordnung über
Verbote und Beschränkungen des Inverkehrbringens
gefährlicher Stoffe, Zubereitungen und Erzeugnisse
nach dem Chemikaliengesetz (Chemikalien-
Verbotsverordnung - ChemVerbots V) 18 Juli 1996.
(8) Krajenbrink, G.W., Temmink, H.M.G., Zeevalkink,
J.A. & Frankenhaeuser, M. “Fuel and Energy
Recovery”. Consortium Report TNO-MEP -
R 98/220 for European Commission Directorate-
General XVII Energy. January 1999
(9) Lehner T. & Vikdahl A. “Integrated recycling of
non-ferrous metals at Boliden Ltd.Rönnskär Smelter”.
Paper presented at ‘Sulfide Smelting 98’,
San Antonio, Texas 1998.
Websites:
American Plastics Council:www.plastics.org
APME:www.apme.org
Boliden (Sweden):www.boliden.ca
Bureau of International Recycling:www.bir.org
Institute of Scrap Recycling Industries:www.isri.org
Dow Europe:www.dow.com
Noranda (Canada):www.noranda.advancedmaterials.com
Norddeutsche Affinerie (Germany):www.affinerie-hamburg.com
Outokumpu (Finland):www.outokumpu.fi
Union Minière (Belgium):www.um.be
21
REFERENCES
AND WEBSITES
A V E N U E E . V A N N I E U W E N H U Y S E 4
B O X 3 B - 1 1 6 0 B R U S S E L S
A P M E ’ S T E C H N I C A L A N D E N V I R O N M E N T A L C E N T R E
T E L E P H O N E ( 3 2 - 2 ) 6 7 5 3 2 5 8
F A C S I M I L E ( 3 2 - 2 ) 6 7 5 4 0 0 2
F o r d e t a i l s o f A P M E p u b l i c a t i o n s s e eA P M E ’ s w e b s i t e o n h t t p : / / w w w . a p m e . o r g
8036
/GB
/07/
00