Oschatz Non-Ferrous Metallurgy En

Cooling of hot and sticky dust-loaded process gases

Non-ferrous Metallurgy

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Transport of a pre-fabricated waste heat boiler downstreamflash smelting furnace in South Australia

Oschatz is an innovative company operatingon a global scale in plant construction, ener-gy recovery and environmental technology.With more than 160 years of experience,Oschatz is today a leading company withreference to the non-ferrous metallurgy, theiron and steel metallurgy, the chemical indu-stry and the environmental technology.

Our customers particularly appreciate ourfirst class global service which goes far be-yond installation and commissioning.

Problem solutionsfor the non-ferrous industryOschatz waste heat boilers are used world-wide since decades for all production proces-ses of non-ferrous metals like copper, zinc,lead, nickel or tin. The engineers develop tai-lor made solutions for our customers basedon the specific process demands and needsfor every plant and process, fully in line withthe overall objective of maximizing producti-vity and profitability.

The hot and sticky dust-loaded processgases and the various processes in the non-ferrous metallurgy present a challenge forour gas cooling and heat recovery technolo-gy. Because of the most advanced productionpractices for waste heat boilers combinedwith innovative cleaning systems for effecti-ve heat transfer, safe and reliable processwaste heat boilers are produced. By future-oriented solutions for the different processes,our customers have the opportunity – evenafter decades of operation – to increase theprocess capacity after simple and quickmodifications at the boiler.

All Oschatz plants are produced with themost advanced technology so that they runin an optimal and very reliable way evenafter thousands of operation hours.

Depending on the location of the custo-mers, systems and components are producedin either Istanbul, Turkey, or Nanjing, China:both production facilities are equipped withstate-of-the-art production machinery andwork naturally in compliance with the inter-national quality standards such as ASME,Pressure Equipment Directive (PED), TRD/AD,ISO 9001, etc. All Oschatz products stand outwith highly appreciated qualities and aremaintenance-friendly with easy accessibilityto the various components.

Oschatz – best technology backed by experience

At home in the world

The waste heat boilers in the non-ferrousindustry are usually designed as evaporationsystems based on the wide range of technicalstandards valid on a world-wide scale.

Oschatz designs the waste heat boilers withtwo types of water-circulation systems:

■ combined natural and forced circula-tion (e.g. two-pass vertical boiler with convection pass),

■ forced circulation only(e.g. horizontal boiler).

The choice of the waste heat boiler type andwater circulation system depends on thegeometry and the location of the processfurnace outlet.

On the basis of many years of developmentand experience Oschatz designs and manu-factures:

■ membrane wall elements,■ evaporator/ superheater screens,■ evaporator/ superheater bundles,■ wall, screen and bundle hammering

systems,■ soot blowers for special cases.

The wide range of products available fromOschatz meets the process requirements ofthe non-ferrous industry all over the world.Oschatz can guarantee a gas cooling perfor-mance to meet the customers' demands,based on given gas inlet conditions.

Waste heat boilers for the non-ferrous metallurgical industry

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Processes and solutions

Non-ferrous Metallurgy

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Flash smelting of copper and nickel concen-trates takes place in a furnace with reactionshaft (Outokumpu flash smelting process).The process gases are cooled in a specialwaste heat boiler. The products are tradi-tionally processed further on in a converter.Another flash smelting process is the Kivcetprocess for lead smelting. Here the processgases are cooled with two waste heat boi-lers. One boiler is installed downstream thesmelting furnace, the other boiler is installeddownstream the electric furnace.

The waste heat boilers are equipped withmembrane walls, screens and bundles. Toavoid corrosion in the waste heat boilers thewater/ steam-side operating pressure is typi-cally chosen between 40 and 70 bar. De-pending on the SO2/ SO3 concentration in theprocess gas it is then assured that the tempe-rature of the boilers' surfaces lies significant-ly above the sulphuric acid dew point. It isimperative for the boiler surfaces to be keptas clean as possible in order not to exceedthe maximal allowed gas temperature for thefilter unit. Exactly for this purpose Oschatzhas developed and patented a highly effi-cient hammering system for the cleaning ofthe boiler surfaces.

Flash smelting of copper and nickel

Efficient and profitable

Design range

Offgas rate 15,000 - 140,000 m3(STP)/hOffgas temperature at boiler inlet 1,250 - 1,400 °COffgas temperature at radiation chamber end 600 - 800 °CSulphation air 2,300 - 21,000 m3(STP)/hOffgas temperature at convection section end 350 - 400 °CFeed water temperature 105 - 140 °CSteam pressure 40 - 70 barSteam temperature 250 - 285 °CSteam rate 10 - 90 t/h

Waste heat boiler downstream flash smelting furnace in Olympic Dam, Australia

Flash smelting furnace with waste heat boiler

Kivcet furnace with waste heat boilers

Waste heat boiler assembly in the workshop

In principle the horizontal waste heat boilerdownstream Outokumpu flash smeltingprocess consists of a radiation chamber inwhich the gas is cooled down to 600 °C –800 °C and an adjacent convection part inwhich convection heating surfaces are instal-led. For the Kivcet process each radiationchamber of both boilers consits of two verti-cal shafts. The convection part is also hori-zontal. The typical gas outlet temperature isapproximately 350 °C.

The succesful handling of the thermalexpansion of the boilers in smelter conditionsis an essential factor for maximum availabili-ty and avoidance of leakages. This is realisedby flexible pendulum supports that keep theboilers in position.Thereby the horizontal for-ces are minimised and the boiler screens andbundles are essentially better accessible formaintenance works.

Design range

Reaction shaft

Offgas rate 20,000 - 25,000 m3(STP)/hOffgas temperature at boiler inlet 1,200 - 1,300 °COffgas temperature at radiation chamber end 550 - 700 °COffgas temperature at convection section end 350 - 400 °CFeed water temperature 105 - 140 °CSteam pressure 40 - 70 barSteam temperature 250 - 285 °CSteam rate 20 - 40 t/h

Electric furnace

Offgas rate 5,000 - 10,000 m3(STP)/hOffgas temperature at boiler inlet 1,300 - 1,350 °COffgas temperature at radiation chamber end 550 - 700 °COffgas temperature at convection section end 350 - 550 °CFeed water temperature 105 - 140 °CSteam pressure 40 - 70 barSteam temperature 250 - 285 °CSteam rate 2 - 10 t/h

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Non-ferrous Metallurgy

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In the in-bath lance smelting technology forthe recovery of copper, nickel, lead, zinc andtin, the process gas has a temperature rangebetween 1,200 °C to 1,550 °C. The gas isdirected into a waste heat boiler to be cooledand to change the dust properties from themolten to the dry phase. Depending on theconcept of the whole plant the process gas iscooled down between 600 °C and 900 °C ina two-pass vertical boiler or down to approx.350 °C in a three-pass vertical/ horizontalboiler. The dust is partly separated in thewaste heat boiler.

The further dust separation takes place ina baghouse or an electrostatic precipitator.When saturated steam is not used, it is con-densed in an air cooled condensator whichis installed above the steam drum. Whileusing recycling material, the steam pressureand temperature can be lower as the aciddew point is lower, too.

The first part of the waste heat boiler upta-ke is made even and smooth on the inside soaccretions can fall off easier. This part canalso be removed for access to the furnaceand boiler. An evaporation cooled furnaceroof operating above the acid dew point hasa longer life time than water cooled roofsand is easy to remove. A relief door is arran-ged at the top of the furnace. It can also beused as a pressure relief door to control smallpressure fluctuations of the offgas.

Lance smelting and converting of copper, nickel, lead, zinc and tin

Economical and clean

Design range

Offgas rate 15,000 - 140,000 m3(STP)/hOffgas temperature at boiler inlet 1,200 - 1,550 °COffgas temperature at radiation chamber end 600 - 900 °COffgas temperature at convection section end 350 - 400 °CFeed water temperature 105 - 140 °CSteam pressure 40 - 70 barSteam temperature 250 - 285 °CSteam rate 10 - 90 t/h

Waste heat boiler downstream ISASMELT furnace in Mount Isa, Australia

ISASMELT furnace with waste heat boiler

Know-how

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Originally, in the in-bath lance smelting tech-nology, the brick-lined furnaces and hoodsare surrounded by a water cooled jacket.Oschatz supplies a furnace and hood coolingthat is integrated into the evaporationsystem of the waste heat boiler.

These components are designed as gas-tight welded membrane walls. In order toprotect the membrane walls from excessiveheat load, they are equipped with studs onwhich a thin castable layer is applied. Thelifetime of these components comply withthe usual average lifetime of boiler pressurecomponents.

Compared to this the time interval for thebrickwork relining of an originally watercooled construction normally lasts less thana year.

The engineering concept developed byOschatz leads to significantly less shutdownintervals resulting in significantly reducedproduction losses and therefore assures abetter economic efficiency of the wholeplant.

Leach residue smelting and fuming of zinc

Innovative and cost-effective

Know-how

Design range

Smelting furnace

Offgas rate 15,000 - 120,000 m3(STP)/hOffgas temperature at boiler inlet 1,250 - 1,800 °COffgas temperature at boiler outlet 350 - 900 °CSteam pressure 30 - 70 barSteam rate 11 - 90 t/h

Fuming furnace

Offgas rate 5,000 - 80,000 m3(STP)/hOffgas temperature at boiler inlet 1,300 - 1,550 °COffgas temperature at boiler outlet 350 - 750 °CSteam pressure 30 - 70 barSteam rate 4 - 60 t/h

Ausmelt furnace with waste heat boiler

Two-pass vertical waste heat boiler

Non-ferrous Metallurgy

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The metallurgical treatment of residues inthe non-ferrous metallurgical industry beco-mes more and more important. Smelting in acyclone constitutes a future-oriented techno-logy for the recovery of the metal containedin the residues. This technology has beenused for iron, lead, copper and zinc and isbased on the well-established CONTOP®-system of the non-ferrous metallurgy. In thepresent application the cylone serves forrecycling of steel flue dust and Zn retort resi-dues containing ZnO and PbO.

The steel mill dust and zinc retort residuesare wastes that contain Zn and Pb, otherheavy metals, coal and slag formers (CaO,SiO2 and FeO). The dust and residues need tobe cleaned and deposited in an environmen-tally acceptable way. During the process theresidues are melted to a slag in a cyclone, Znand Pb are fumed. The fumed metals arepost-combusted in a waste heat boiler to oxi-des and recovered as dust from the gas flow.

The gas cooling system for the smeltingand fuming cyclone and the waste heat boi-ler for this process have been supplied byOschatz. Only a small quantity of mechanicaldust results from the cyclone smelting. As thecyclones are connected to an evaporationsystem, the thermal load is better handledthan with a cooling water system, and thesurface temperature of the cooling tubes isalways kept above the dew point of H2SO4

and HCI.

Cyclone smelting and waste heat boiler for zinc residue and steel dust recycling

Future-oriented technology

Design range

Cyclone smelting

Cyclone diameter 1 - 3 mFeed rate of solids 10 - 100 t/hOffgas temperature at cyclone outlet 1,200 - 1,800 °CSteam pressure 30 - 70 barSteam rate 3 - 10 t/h

Waste heat boiler

Offgas rate 5,000 - 50,000 m3(STP)/hDust at boiler inlet 0.7 - 7 t/hOffgas temperature at boiler inlet 1,200 - 1,800 °CDust at boiler outlet 0.8 - 8 t/hOffgas temperature at boiler outlet 240 - 380 °CSteam pressure 30 - 70 barSteam rate 6 - 60 t/h

Smelting reactor, CONTOP®-system by Siemens VAI

Steel dust and zinc residue recycling with cyclone smelting and waste heat boiler

Benefits:

■ very high energy density,■ optimal reaction conditions and mass

and heat exchange by high turbulence intensity,

■ reduced reactor dimensions with high throughput,

■ high smelting temperatures (> 2.000 °C)are possible, for instance in reactions with oxygen enrichment,

■ larger particle size than in comparable entrained flow reactors possible.

Roasting of zinc, pyrite and copper concen-trates is carried out in fluidized beds. For thisprocess Oschatz supplies waste heat boilersincluding the coils for the fluidized beds. Thehot roaster gases (800 to 1,000 °C) with ahigh dust load (up to 400 g/Nm3) are cooledin Oschatz boilers down to approximately350 °C.

In general these boilers are being equip-ped with cooled tube walls, evaporationscreens and convection superheater screens.Because of the gas composition of the pro-cess and the corresponding dust characteri-stics, a steady operation of the waste heatboilers can only be achieved by highly effi-cient heating surface cleaning systems whichdo not require a maintenance shutdown forthe whole plant.

The high dust load of the gases of upto 400 g/Nm3 requires the development ofhighly effective mechanical cleaning systems.Cleaning of boiler heating surfaces by theOschatz hammering system has been provento be very successful.

Fluidized bed roasting for zinc, pyrite (gold) and copper

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Highly efficient

Non-ferrous Metallurgy

Design range

Offgas rate 15,000 - 120,000 m3(STP)/hOffgas temperature at boiler inlet 800 - 1,000 °COffgas temperature at boiler outlet 350 - 400 °CFeed water temperature 105 - 140 °CSteam pressure 42 - 70 barSteam temperature 250 - 400 °CSteam rate of boiler 6 - 50 t/hFluidized bed cooling coils 3 - 50 t/h

Waste heat boiler downstream roaster for gold recovery in Newmont, USA

Fluidized bed roaster with waste heat boiler

Know-how

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Cleaning of waste heat boiler cooling surfaces

Innovative and reliable

The Oschatz boiler hammering cleaningsystem is the result of 50 years of develop-ment and experience. The special patentedhammering system provides an extraordinarycleaning effect for slag and dust, withoutdamaging the boiler.

Oschatz hammers hit the heating surfacesof the boiler within the tensile strength limitsof the steel. Hammer, anvil, boiler and buck-stays are not overstressed, without anyplastic deformation of the steel when subjectto high impacts.

Oschatz hammers hit on well-definedpoints permitting maximum acceleration andhave a variable cleaning vibration frequency.

Know-how and activitiesOschatz special know-how Examples

Gas-handling system analysis Material and energy balances/equipment selectionProcess Smelting, converting, sulphation, post-combustionPost-combustion and sulphation Dosing and mixing tests for combustion airCleaning of cooling surfaces Life-time tests of surface and hammering system (patent)Corrosion and erosion Corrosion and erosion testsInfiltration air reduction Pressure air sealingCapacity increase and modernization Screens, bundles, bed cooling elements, boiler enlargementFurnace and reactor cooling Evaporation-cooled cyclone, furnace and roof cooling

Know-how

Oschatz offers three types ofheating suface cleaning systemsfor:

■ boiler walls,■ screens,■ evaporator bundles.

For the boiler wall cleaningsystem a hammer hits an anvilthat is directly mounted on theboiler wall. For a screen bundleeach screen has its own ham-mer positioned outside of the boiler at the top.This hammer hits in the direction of the gasflow. The bundles are hammered at the bottomwith one hammer hitting two bundle layers.

The Oschatz hammering cleaning system is usedsuccessfully for the dust removal in waste heatboilers downstream flash smelting, ISASMELT,Ausmelt and roasting processes.

Test unit of a cooling surface cleaning system

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Non-ferrous Metallurgy

Conception, text and layout: commedia, Essen · Photos: Oschatz · Print: grafistar

The new Oschatz production facility near Istanbul, Turkey

Istanbul, TurkeyOschatz has been manufacturing boilersand waste heat systems, i.e. heat recovery,at its workshop in Istanbul since 1997, forcustomers located all around the world. Theproduction facilities at Gebze-Kocaeli, loca-ted on a 21,000 m2 (226,000 ft2) site on theimmediate outskirts of the Turkish metropo-lis, offer 5,000 m2 of floor space – plenty ofroom in which to manufacture vessels with amaximum diameter of 6.5 metres to ASME,TRD/AD and ISO 9001 standards and in com-pliance with the EU’s Pressure EquipmentDirective (PED). In an initial expansion phasescheduled to be completed in 2010, produc-tion is being relocated and expanded. 50kilometres from our present location, we areconstructing four new factory buildings witha production area of 10,000 m2 (108,000 ft2)on a 60,000 m2 (646,000 ft2) site locatedimmediately next to the sea.

Our production facilities in Turkey and China

Nanjing, ChinaTo be able to supplythe markets in Asia,Australia and Oceaniafaster and more cost-effectively, Oschatz hasbuilt a second produc-tion facility in Nanjing, China. The productionbegan in October 2005. A second expansionphase at this facility was completed onlythree years later in the summer of 2008. Inseven production halls with a total floorspace of 15,000 m2 (161,000 ft2), located ona 50,000 m2 (538,000 ft2) site with good con-nections to the port of Changjiang, Oschatznow manufactures waste heat boilers andcooling stacks in accordance with the ChineseGB, ASME, PED, TRD/AD and ISO 9001 stan-dards. 650 people are now employed here –under European management – in producti-on, design, finance and procurement.

The Oschatz production facility in Nanjing, China

Fast and customer-oriented

Oschatz GmbH Westendhof 10-12 45143 EssenGermany

Tel. +49 201 1802-0Fax +49 201 1802-165www.oschatz.com