Boliden Kokkola Oya pioneer in zinc technology

Boliden is one of the leading min-ing and smelting companies inEurope with approximately 4,500employees. The groups produc-tion plants are in Finland,Sweden and Norway. The grouphas mines in Sweden andIreland.

Boliden's main products are zinc andcopper, in addition to which the com-pany also produces gold, silver and lead.The company has two zinc plants, onein Kokkola, Finland and another inOdda, Norway.

The top of the zinc worldThe zinc plant in Kokkola started oper-ations in 1969. Thanks to determineddevelopment work, it is now one of theleading zinc manufacturers in the world,

whose products are renowned for theirhigh quality both at home in Finlandand on the international market.

The zinc plant in Kokkola is one ofthe biggest zinc plants in the world. Itsannual production capacity is 306,000tonnes a year. The main products arepure zinc and zinc alloys.

The zinc plant has adopted a mode ofoperations which aims at continuousdevelopment. Our position at the top ofthe zinc world is based on a high degreeof automation, use of the latest produc-tion technology in the sector and ondevelopment of our own process.Thanks to these efforts, we are able toproduce zinc efficiently in an environ-ment-friendly and energy-efficient man-ner.

Our operations are certified in accor-dance with the ISO 9001 quality man-agement system, ISO 14001 environ-mental management system andOHSAS 18001 occupational health andsafety management system.

A specialist in the fieldGreat expertise is required for the man-ufacture of high-quality zinc. At the zincplant in Kokkola, quality is ensuredthrough a highly advanced productionprocess and skilled staff, who possess in-depth qualifications in zinc production.It is the skills and knowledge of our

expert staff that have enabled BolidenKokkola to become an internationalpioneer in the field of zinc.

We have sought new solutions to zincproduction in an unpre judiced way.One of the results is the method ofdirect leaching of zinc concentratedeveloped at Kokkola, which hasbrought more variety to the range ofzinc concentrates available to zincplants.

In order to ensure competitiveness, it

Boliden Kokkola Oy is a

know ledgeable and fair

company to do business with.

You can always count on

our products and promises.

Dependableskill

is important to master the entire chainof zinc production, from acquisition ofraw materials to sale of the finishedproduct. The deep-water port on thepremises of the Kokkola plant providesus with a good logistics base, somethingthat the customer benefits from in theform of unfailingly reliable deliveries.

Dependable cooperationThe strength of the zinc plant inKokkola is in its highly skilled and

motivated staff, whose wellbeing isimportant to us. According to our view,wellbeing at work is founded on beingable to cope with ones job mentally,and in order to do this, it is importantto feel in control of ones own work.

The production technology we use issafe, both for the environment and forthe people who control the process. Ouraim is to have an accident-free workenvironment, and we take occupationalsafety and health-related matters into

account in every aspect of planning thework and in peoples practical tasks.

Boliden Kokkola Oy is the biggestprivate employer in Kokkola. We are askilled and fair partner for our clients,our staff and other stakeholder groups, a partner whose product and promisescan always be depended on.

Zincs high quality and complete reliability provide the basis for confidential customer relations.

Most of the raw material usedby the zinc plant comes frommines in Europe and NorthAmerica. Our principal rawmaterial is sulphidic zinc con-centrates, with a zinc contentof just over 50 per cent.

In order to get the best results, we mixdifferent types of concentrate, whichare processed into high-quality metal-lic zinc in our production process.During its various stages, the produc-tion process also produces energy andother substances which are utilized bythe zinc plant itself, turned into prod-ucts for sale or removed from theprocess.

RoastingAt the first stage of the productionprocess, the zinc concentrate is fedinto two parallel fluid bed roasters,where the concentrate is roasted at atemperature of 950 degrees Celsius.

The sulphur dioxide gas produced

during the roasting is cooled and theheat it contains is recovered. Pure mer-cury is separated from the gas andprocessed into a saleable product. Thesulphur dioxide in the gas is used forthe manufacture of sulphuric acid.

LeachingNext, the zinc calcine resulting fromroasting and the concentrate fedthrough direct leaching are leached insulphuric acid recycled from electroly-sis, and this produces zinc sulphatesolution. Iron is precipitated and fil-

tered from the process in the form ofjarosite.

The sulphides in the concentrate areoxidized into elemental sulphur, whichis separated from the jarosite throughflotation. The resulting concentrate isfiltered, washed and stored in a sepa-rate basin.

Solution purification After leaching, the zinc sulphate solu-tion contains small amounts of impuri-ties, which must be removed from thesolution through precipitation beforeelectrolysis. Purification is performed ina continuous three-stage process.

After the third stage of the purifica-tion process, the zinc sulphate solutionwill contain about 150 grammes ofzinc per litre. The solution is cooledand pumped into the electrolysis stage.

ElectrolysisThe zinc is separated from the solutionusing an electric current. Metallic zincis precipitated onto aluminium cathode

Modern technology is kindto the environment

RoastingSO2Hg

Concentrates Leaching

Fe, S

Solution purification

Cu Co, Ni Cd

Electrolysis Casting

Boliden Kokkola is an

international pioneer

in zinc technology.

plates where it is allowed to build upfor about 36 hours.

The cathodes are then removed fromthe solution and replaced with newcathodes. The zinc is stripped from thealuminium plates using automaticstripping machines.

Smelting, alloying, and castingThe cathode zinc is smelted in electricfurnaces, and the zinc is then cast ineither 25 kilo ingots or jumbo ingots ofup to 2,000 kilos. The jumbo ingotsare alloyed with aluminium or othermetals according to the customersspecifications.

After all the stages in this process arecomplete, the zinc is a finished andsaleable product. As much as 85 per

cent of the zinc produced at Kokkola isexported. Our customers operate in theEU.

Responsible production methodsThe foremost aims in the continuousdevelopment of process technology are

efficiency, profitability, and attention toenvironmental impact. At BolidenKokkola, efficient production andrespect for the environment go togethernaturally, since use of the latest tech-nology enables us to minimize environ-mental impact.

Our own research operations developnew solutions which help reduce theenvironmental impact from our pro-duction even more. We have attainedsignificant results both in limitingemissions and conserving energy.

Boliden Kokkola makes use of the most up-to-date technology in its production.

An essentialmetalZinc leaves our plant in Kokkolain the form of zinc ingots orjumbo ingots, but in actual factzinc is a gift from MotherNature that is constantly pres-ent in our lives. Zinc plays animportant part in the cycle oflife and it therefore existseverywhere in our environment in both soil and water.

All living beings require zinc to growand develop. For human beings, zinc isan essential trace element which sup-ports many of our vital functions.Without zinc, there would be no life.

Galvanizing is a durable solutionZinc has many uses as a metal. It is thefourth most used metal in the worldafter iron, aluminium and copper.

Zinc is mostly used to protect steel

from corrosion. Zinc forms a protec-tive layer over the surface of the steel,making steel products more durable.Even a very thin layer of galvanizingwith zinc can multiply the useful lifeof a steel product. A galvanized steelsurface needs no maintenance.

In extending the useful life of prod-ucts in this way, zinc saves considerablenatural resources and energy whichwould otherwise be needed to manu-facture new products. Zinc is adurable solution both for the indi -vidual product and the environment at large.

Steel products can be galvanized inmany different ways. The choice ofmethod influences the durability of theproduct, its appearance and itsmechanical properties. The use of zinchas grown most rapidly in the buildingindustry, the automotive industry andthe transport industry, where productsare required to last a long time.

Brass looks goodWhen zinc and copper are alloyed, theresult is brass, which is a very versatilematerial thanks to its special character-istics. Brass has an earthy, warmcolour, which makes it popular inarchitecture and interior decoration.Brass is also inexpensive and easy towork. Brass products include various

types of doorknobs and door handles,fittings, vents and fixings.

Zinc has many usesDie-cast zinc is an excellent castingmetal. Some of the products made ofdie-cast zinc that everyone is familiarwith include door handles, locks, thelocking mechanisms of zippers and vari-ous tools and machines. Rolled zincproducts are used in the building indus-try for roofs, cladding and guttering.

Some zinc is used for the manufac-

Most zinc is used as

protection against

corro sion in steel

products.

Copyright 2004 Rautaruukki Oyj

turing of zinc-based chemicals. The useof zinc oxide is well-established in therubber and car tyre industries and thecosmetics and pharmaceuticals indus-tries. Zinc powder is used in the manu-facture of special anti-corrosive paint.

Raw material of the futureZinc is a valuable material even afterthe end of the lifespan of a zinc prod-uct. Zinc can be recycled indefinitelywithout any change in its physical orchemical properties.

By now, about 30 per cent or 2.9million tonnes of the zinc raw materialused every year comes from recycling.It is predicted that this percentage willincrease even more as more scrap isrecycled.

Zinc products which are recycled areused for the manufacture of zinc oxideand zinc powder. Most of the zincused in the rubber and car tyre indus-tries and in paint manufacture is recy-cled raw material.

The maintenance-free lifespan of

zinc products and galvanized goodsmay be up to 100 years at its best, sozinc comes back for recycling at a veryslow rate. However, the excellent recy-cling potential ensures that the zincmanufactured at Kokkola today will bevaluable raw material for generationsto come.

Zinc makes a sustainable solution from the point of view of the product and the environment.

Boliden Kokkola Oy, P.O.Box 26, FI-67101 Kokkola. Visiting address Outokummuntie 8Tel. +358 6 828 6111, Fax +358 6 828 6005, www.boliden.com Gr

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