Alexis Métais - 5th ICEP, 11/05/2011

Achievements in Industrial Ozone Bleaching

Modernizing or building their pulp mills, several pulp producers still consider the 30 years old ECF bleaching as the only option.

But, considering the very good and reliable results achieved by industrial ozone bleaching, such a conservative attitude can not be justified any longer.

Introduction

First industrial production of ozone bleached pulp started in 1992.

At the beginning, ozone bleaching development was linked to the increasing environmental pressure.

Introduction

Today the choice of ozone is mostly justified by the economical savings resulting from chemicals costs cut-off.

In May 2011, 22 mills worldwide use ozone bleaching and deliver a pulp quality similar or better than conventional ECF bleaching would do.

Introduction

Ozone Generation

Ozone production requires only Oxygen & Energy. It is a pure on-site technology needing neither delivery nor storage

Producing 1 kg ozone requires:- 10 kWh (all included)- 8.3 kg of pure oxygen

At the generator’s outlet, the gas mixture contains

7.3 kg oxygen and 1 kg ozone(concentration of 12 % by weight)

• Since 2000, ITT WEDECO has developed Z-Compact system which is an ozone plant completely pre-assembled at factory offering the following advantages:

• Complete test run before shipment• Solution “plug & play”• Fully protected from ambient

conditions• Minimal foundation work & foot print

Ozone Generation

Modularity combining “on site” chemical production & supply is today a key success factor for ozone production .

Example : Fibria Jacarei with 4 Z-Compact systems in operation• Nominal ozone production on site : 750 kg/h (18 tons/day ozone)• Peak capacity : 1 ton/h (24 tons/day ozone)

Ozone Generation - Availability

Example in Brazil Contract was 98% on monthly base.

What are the numbers ?

Availability 01.-08. 2010 2009 2008 2007 2006 2005

Total (without Oxygen plant)

99.9% 99.9% 99.9% 99.9% 99,40% 98,80%

Container 99.7% 99.5% 99.0% 99.0% 99% 98%

Oxygen compressor 99.0% 99.0% 99.0% 100% 99% 98%

Chiller 99.5% 99.4% 99.0% 99.9% 99% 99%

Destructor 100% 100% 100% 100% 100% 99%

MCC 100% 100% 100% 100% 100% 100%

Oxygen plant 98% 98% 98% 99% 98% 98%

Z-stage – High Consistency

C-Free® ZeTracTM

HC ozonation is carried out at atmospheric pressure in 1 min.

Ozonated pulp is then sent without intermediate washing to a 5-10 minutes long extraction stage.

Such a solution allows to recycle the E filtrate back to the furnace and lower the total bleaching effluent to 4-8 m3/adt.

Z-stage – Medium Consistency

In 2004, Lenzing upgraded its 2 bleaching lines with modern mixers: it resulted in a 2.5 ISO brightness points increase for the same ozone dose.

Z-stage – Operating Parameters for HW

Initially Z-stages were operated at 40-45°C.

In Mondi Ruzomberok increased temperatures improve ozone bleaching efficiency but do not impact mechanical properties:

A similar study made Domtar Espanola operating the Z-stage at 70°C.

Today most of the HW Z-stages operate in the 55-70°C range.

Temp in Z 43°C 43°C 58°C 61°CKappa number after Z(EO) 4.1 4.0 4.0 3.8 ClO2 charge, kg/adt (DCS data) 24.5 23.5 24.7 24.4 Brightness, % ISO 85.9 85.2 86.6 87.7 Reverted Brightness, % ISO 81.8 82.2 83.9 85.9

Z-stage – Operating Parameters for HW

As a result of an increased temperature, steam requirementscan be 75% lower when ozonebleaching is implemented:(industrial figures)

Green Bleaching consists in maximizing the use ofgreen chemicals and their by-products.

Example of Celtejo (Portugal):

Pulp production: 720 adt/d (Eucalyptus, Pine)Brightness: 90 % ISO

Flexible bleaching process: (OO)ZeDD, (OO)ZeDP & (OO)ZePP

Total bleach plant effluent volume:6-8 m3/adt for light-ECF

4-6 m3/adt for TCF

Green Bleaching

ambient air

Pulp out

Pulp in

Z-StageTOWL

Oxygen Delignif.

OxygenOxygenApplicationsApplications

Gas scrubber

Ozone DestructionSystem

Compressor

OzoneGenerator

OxygenPlant

LOXtank

OxygenBack-up

34 t/day O2 30 t/day O2 +4 t/day O3

30 t/day 02available

17.5 t/day 02

12.5 t/day 02

Green Bleaching

1998: Domtar Espanola (Canada)

Pulp production: 800 adt/d (Birch, Aspen, Maple)

Brightness: 93 % ISO

In 1998, Domtar Espanola switched from O-A-D-E-DnD to O-A-ZD-E-DnD.It was noticed:

1. no impact on viscosity or mechanical strength2. a replacement ratio from 2.2 to 3.53. a bleaching costs reduction of 10%

POD PO

Pulp production: 480,000 adt/y (HW and SW)

Brightness: 89+ % ISO

PFI 28 SR - HW:Breaking length (km) 7.8 - 8.5 Tear index (mNm2/g) 5.8 - 6.5Stiffness (mN) 125 - 135Viscosity (cm3/g) 650 - 700

In 2005, the mill set a new world record for copy paper production at 1500 m/min. The paper machine is still today the 3rd fastest worldwide for such a production

PFI 28 SR - SW:Breaking length (km) 11 - 12Tear index (mNm2/g) 9.5 - 10.5Stiffness (mN) 125 - 135Viscosity (cm3/g) 550 - 600

Mondi Ruzomberok (Slovakia)

ITC Bhadrachalam (India)

Pulp production: 500 adt/d (Eucalyptus, Subabul and Casurina)

Brightness: 89+ % ISO

ITC’s feedback concerning ozone bleaching is the following:

1. overall strength properties improved by 5%2. about Rs 450 per MT saving in bleached pulp cost of production

Savings of 7.25 €/adt3. 1 kg of Ozone replaces 5-6 kg ClO2 as active Cl2

Line 2

Eucalyptus pulp production: - 1,200 adt/d on line B

- 2,500 adt/d on line C

Brightness: 90+ % ISO

Producing 1,300,000 adt/y, Fibria Jacarei is the biggest mill using ozone bleaching.

The mill just contracted a new Z-Compact-System

to increase capacity on line B.

Fibria Jacarei (Brazil)

Line C

Oji Paper Nantong (China)

Pulp production: 1600 adt/d (Eucalyptus and Acacia)

Brightness: 90+ % ISO

Start-up: 2012

The Oji Paper mill in Nantong will be

the first Greenfield mill built with an ozone stage

In the near Future…

Results presented by Metso - Zetrac forum

April 27– 28, 2011, Pousada do Crato, Flor da Rosa, Portugal

In the near Future…

… an A(Ze)(PO) bleaching sequence would allow to bleach eucalyptus pulp to 92% ISO with 3.3 kg/adt O3 and 8 kg/adt H2O2!

Ozone bleaching technology has improved a lot in the last 20 years. It is today: - a well proven technology

- a reliable on site chemical production- a safe, stable and flexible process- used by some reference pulp mills worldwide.

Ozone bleaching allows to reach those 4 targets at once:

1. Lower the effluents amount combined2.Improve effluents quality 3. Produce pulp with similar or better strength properties, 4. Lower bleaching chemical costs by at least 20%

Conclusions

Sustainable development is your ambition…

Ozone Bleaching is our solution!

Fibria Jacarei, Brazil

MUITO OBRIGADO PELA VOSSA ATENÇÃO !