THE VERSATILITY OF OUTOTEC’S AUSMELT PROCESS FOR LEAD PRODUCTION

Stefanie Creedy, Markus Reuter, Stephen Hughes, Gavin Swayn, Ross Andrews and Robert Matusewicz

Outotec Ausmelt Pty Ltd

12 Kitchen Road

Dandenong, 3175, Victoria, Australia

(correspondence: name.surname@outotec.com)

ABSTRACT

Outotec’s Ausmelt Process is well suited to applications where existing technologies are unable to

meet the high standards set by today’s energy and eco-conscious world. With the depletion of high grade

primary lead sources, lead producers are looking for new technologies to process lower grade concentrates and

secondary (post-consumer) materials, usually within the same vessel to save on capital and operating

costs. This paper will discuss the development and options available with Outotec’s Ausmelt Process for lead

smelting including smaller scale lead projects by providing low-cost, automated and environmentally

responsible smelting solutions.

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INTRODUCTION

Increasing lead demand has been largely driven by growth in the automotive industries in the

developing world, especially China and India. With this growing abundance of spent lead acid batteries and the

depletion of high grade primary lead resources, there have been an increasing number of secondary lead

recycling projects. Currently secondary (recycled) lead accounts for around 60% of the global lead production

per annum [1].

With the inherent limitations of the traditional sinter oxidation – blast furnace processing route

producers are seeking to adopt modern technologies to process low grade concentrates and secondary (post-

consumer) materials, more often now within the same operation. Outotec’s Ausmelt Process is well suited to

applications where existing technologies are unable to meet the increasing stringent hygiene and environmental

regulations. Offering flexible, low cost environmentally friendly direct smelting, Outotec’s Ausmelt Process is

considered a leader within the industry. To capture small scale lead-acid battery recycling projects Outotec

Ausmelt has been working with Gravita Exim to provide low cost standardized plants.

Outotec’s Ausmelt Process has gained widespread commercial acceptance in non-ferrous smelting and

recycling applications. It is highly flexible and efficient, with the capacity to process primary and secondary

feeds using a variety of fuels, to deliver high recoveries and excellent environmental performance. The

versatility of the Ausmelt Process allows furnaces to be customized to suit individual applications and utilize

alternative or existing technologies. Outotec’s Ausmelt Process commercial lead and zinc experience includes

numerous primary and secondary materials such as concentrates, batteries, residues and slags. There are

currently a total of 17 Ausmelt furnaces currently processing lead & zinc containing materials/residues, with an

additional 11 furnaces under design, construction or commissioning phase.

OUTOTEC’S AUSMELT PROCESS

The Ausmelt Process uses top submerged lancing for direct injection of fuel and oxygen enriched air

into a molten slag bath with the intense agitation achieved promoting rapid reaction kinetics due to the optimal

mass and heat transfer processes. Operation with a well sealed vessel under a negative pressure ensures

minimal fugitive dust and gas emissions and higher offgas SO2 concentrations.

Pertinent to the processing of lead and zinc materials is the ability to control the bath oxidation

potential, providing better control of lead and zinc distribution between the metal, gas and slag phases. Bath

turbulence and mixing inherent to the technology also provides the ability to fume volatile species such as lead,

zinc and arsenic.

Figure 1 provides a schematic flowsheet of the Ausmelt Three Stage Lead Process. This flowsheet

consists of smelting, slag reduction and slag fuming stages, however, usually the stages only consist of

smelting and slag reduction with a fuming stage only necessary if zinc recovery is required. The chemistry and

thermodynamics of these stages are discussed in various publications [2] and will not be repeated here. Some

of the main advantages of Outotec’s Ausmelt Process include the ability to:

• produce secondary benign products (recycling/bleeding of fume which may contain harmful

components, or further products i.e. zinc, antimony, arsenic, etc.);

• use concentrates as reductant (dependent on feed composition);

• use oxygen enrichment to achieve higher throughputs and secondary production (sulphuric

acid/gypsum);

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• utilize various fuel options depending on availability and economics (natural gas, fuel coal,

light/heavy fuel oil, bunker coal or plastics);

• allow flexibility of feeds to enable economic capture of the regional market via the use of primary

and secondary feeds or mixes thereof, and

• utilize a single furnace for all processing stages.

Figure 1 - A typical 3 stage Ausmelt Process lead plant

This general arrangement can be used for complete plant configurations, or each of the stages can be

utilized individually and integrated into existing plant operations. The process flowsheet and furnace design are

tailored depending on the clients’ requirements, feeds, feed compositions, throughput and/or existing facilities.

Flexibility to customize the design according to the individual applications and production requirements is due

to the ability to:

• operate in batch, semi-continuous, continuous or campaigned modes;

• integrate with alternative technologies and existing facilities to increase throughput and/or

modernize an operation;

• apply modular design for the implementation of phased upgrades or expansions;

• process a wide range of primary and secondary feeds; and

• control the thermodynamics and process chemistry as required by various feed types.

For projects up to 100,000 tpa of lead, each stage (smelt, slag reduction and fuming if necessary) can

be conducted using a single furnace. These stages are operated in either a batch or campaign mode depending

on the production requirements and economics. To increase production, smelting, slag reduction and fuming

stages are divided amongst multiple furnaces or integrated with alternative technologies or existing equipment.

These projects are usually operated with campaigns or in continuous mode. Alternative technologies can also

be employed for the reduction or fuming stages, if these are available or preferred (e.g. Outotec’s Kaldo

technology). Across a range of non-ferrous projects Ausmelt furnaces have been coupled with blast furnaces,

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electric settling furnaces, QSL, shaft furnaces, Peirce Smith converters, box fumers and numerous

hydrometallurgical operations depending on specific client needs.

COMMERCIAL LEAD OPERATIONS USING OUTOTEC’S AUSMELT PROCESS

The flexibility of the Ausmelt Process is illustrated by the diverse range of lead projects in operation or

currently under design or construction. Outotec’s Ausmelt lead projects are summarized in Table 1.

Table 1 - Outotec’s Ausmelt Process Lead Projects

Project Feed Material Operations Product Mode of

Operation Smelting Slag

Reduction

Fuming

Weser Metall

GmbH

Concentrates,

Battery Scrap

Ausmelt N/A N/A Pb Bullion, High

Grade Slag

Continuous

Namibia

Custom

Smelters**

Polymetallic Pb

Concentrates

Ausmelt N/A Pb Bullion, Discard

Slag

Batch

HZL Concentrates,

Sludge

Ausmelt ISF Pb Bullion, Discard

Slag

Batch

Korea Zinc Concentrates,

Secondaries,

Fume

Ausmelt N/A Pb Bullion, Discard

Slag

Continuous

Campaigns QSL Furnace

Korea Zinc High Pb Slag QSL Furnace

Ausmelt

Ausmelt Pb Bullion, Pb/Zn

Fume,

Discard Slag

Continuous (2 furnaces)

Korea Zinc

(2 plants)

Pb Tailings

Leach Residues

Ausmelt N/A Ausmelt Pb, Pb/Zn Fume,

Discard Slag

Continuous (2 furnaces)

Korea Zinc

(3 Plants)

Leach Residues Ausmelt N/A Ausmelt Pb, Pb/Zn Fume,

Discard Slag

Continuous (2 furnaces)

Young Poong

Corp.

(2 Plants)

Pb Residues

Zn Residues

Ausmelt N/A Ausmelt Pb Fume, Pb/Zn

Fume and/or Zn

Fume

Continuous (2 furnaces)

YTCL * Concentrates Ausmelt Pb Bullion, Zn

Fume, Discard Slag

Batch

Carat* Pb Polymetallic

Concentrates

Ausmelt Electric

Furnace

N/A Pb Bullion, Slag Continuous

Votorantim

Metais*

Concentrates,

Residues, Battery

Scrap

Ausmelt N/A Pb Bullion, Pb/Zn

Fume, Discard Slag

Batch

Intertrust* Concentrates,

Battery Scrap,

Residues, Slag

Ausmelt Ausmelt Pb Bullion, Zn

Fume, Discard Slag

Continuous

Batch

KCM SA* Concentrates,

Battery Paste,

Slimes

Ausmelt Slag

Fumer

(existing)

Pb Bullion, Zn

Fume,

Discard Slag

Batch

HCHM* Concentrates

Residues

Ausmelt Fumer Crude Pb,

Low Grade Slag

Batch

*Currently under design or construction.

**In 2008 the Ausmelt furnace was modified to process polymetallic copper concentrates and reverts.

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3 Stage Batch Process

Yunnan Tin Corporation (YTCL) Lead Smelter, China (2010)

The YTCL flowsheet uses a three stage smelt/slag reduction/fuming batch processes conducted in a

single Ausmelt furnace. Processing 190,000 tpa of lead concentrate the plant will produce lead bullion, a zinc

rich fume and a discardable slag. The process flowsheet is depicted in Figure 1 as shown previously.

3 Stage Campaign Process

Intertrust Holding, Bulgaria (TBA)

As part of a modernization of Intertrust’s existing facilities this project involves the installation of two

Ausmelt furnaces as depicted by Figure 2. Processing 125,000 tpa of lead concentrates, battery scrap, slag and

residues the smelting and reduction/fuming stages will be conducted in separate furnaces.

Figure 2 - Process flowsheet for Intertrust project

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2 Stage Batch Process

Hindustan Zinc Limited, HZL-India (2005), Votorantim Metais-Brazil (TBA) and HCHM-China (TBA), KCM

SA Bulgaria (TBA) and Namibia Custom Smelters-Namibia (1996)

HZL, Votorantim and HCHM are all two stage smelt/slag reduction batch processes conducted in a

single Ausmelt furnace. Originally designed as a 3 stage batch process, HZL are no longer conducting the

fuming stage, processing lead concentrate (ca. 85,000 tpa) to produce lead bullion and a zinc containing slag.

The Votorantim Metais plant will process a blend of lead concentrates, lead-bearing residues, battery

scrap and specified recycles to produce 75,000 tpa of refined lead. HCHM will process lead concentrates, matte

and sulphate residues to produce 66,000 tpa of bullion.

KCM SA is also be a three stage process however only the smelt and slag reduction stages will be

conducted in the Ausmelt furnace with an existing slag fumer being utilized for the fuming stage. This plant

will process lead concentrates, battery paste and slimes to produce 65,000 tpa of refined lead. The process

flowsheet is depicted in Figure 3.

Recycled

Fume

Zn Rich Slag

Discard Slag

Crude

Pb

Bullion

High Lead Slag

Ausmelt

Batch

Smelt

Lead Concentrates

Battery Paste

Waelz Clinker Slimes

Air

Oxygen

Fuel NG

Reductant Coal

Air

Oxygen

Fuel NG

Fluxes

Ausmelt

Batch

Slag Reduction

Fuming

(Existing Slag Fumer)

Air

Oxygen

Fuel NG

Reductant Coal

Zn Oxide

Product

Figure 3 - KCM SA process flowsheet

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Namibia Custom Smelters was processing polymetallic lead concentrates, however, in 2008 due to lack of

concentrates the plant was modified to process copper concentrates and revert materials [3].

Continuous Fuming & Campaign Processes

Korea Zinc, South Korea (1992, 2000, 2001)

Korea Zinc (KZ) employs numerous Ausmelt furnaces at the fully integrated Zinc and Lead plant in

Onsan, South Korea. As Korea Zinc adopted the technology for the treatment of zinc residues, the need for

matching lead capacity arose due to their desire to treat the associated lead containing residues. This included

installation of an Ausmelt furnace in unison with the QSL furnace for treating lead materials [4]. The desire to

increase zinc production then resulted in installation of another Ausmelt furnace to treat lead residues from the

zinc plant and this helped boost overall lead production at the site [5]. The innovative integrated flowsheet

pioneered by Dr. Choi of Korea Zinc is illustrated in Figure 4.

Zn Plant

QSL

Discard Slag

Fume Leaching

Plant

FeedsPb Concentrates

Pb Secondaries

Residues

Ag Cons

Cu

Pb Residue

Zn/Pb Fume

Goethite

Fume

High Pb

Slag

Pb

Pb

Ausmelt

Plant

Ausmelt Residue

Fumers

Ausmelt QSL

Fumers

Slag

Cu

Ausmelt

Plant

Ausmelt Zn

Fumers

Cu Speiss

Zn Solution

Cu Removal

Bi, Ag, AuZn & By products

Cu Speiss

PMR

Leached

Residue

Pb Refinery

BULLION

BULLIONCu Dross

Pb Slime

BULLION

Residue

Ag Conc

Figure 4 - Integrated flowsheet at the Korea Zinc Onsan facility

Korea Zinc now utilize 12 Ausmelt furnaces at the Onsan operation. A further 4 Ausmelt furnaces are

employed at the Korea Zinc subsidiary Young Poong Corporation, to process a further 100,000 tpa of zinc

residues and 120,000 tpa of lead residues also arising from hydrometallurgical operations.

Continuous Smelt

Weser Metall GmbH, Germany (1996) and Carat, Russia (TBA)

Weser Metall GmbH (Recyclex SA - formally Metaleurop SA), continuously smelt concentrates and

battery scrap in a single Ausmelt furnace to produce over 120,000 tpa of lead bullion and a high grade slag

(Figure 5). It was deemed more economical to operate the Ausmelt furnace under a continuous smelt and sell

the high lead content slag rather than conduct a slag reduction stage in a batch or campaign mode to produce a

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discardable slag. Weser Metall GmbH is currently operating at more than 40% above design capacity treating

more than 200,000 tpa of feed materials with a high varying secondary fraction of above 60% [6, 7].

Figure 5 - Weser Metall GmbH (Recylex SA) process flowsheet

The Carat lead plant in Khakassia, Russia is based on the integration of the Ausmelt process with an

electric furnace for slag reduction and cleaning. The feed for this operation will be 170,000 tpa of lead

concentrates and battery paste which will be continuously smelted in an Ausmelt furnace to produce lead

bullion. The lead rich slag also produced will be cleaned in an electric furnace producing a lean-antimony alloy

and secondary slag containing 1.0-1.5 Pb and 7-9% Zn [8]. The process flowsheet is depicted in Figure 6.

Figure 6 - Process flowsheet for Carat project [8]

As with any design linking different unit operations, the optimized flowsheet requires careful

consideration of the process thermodynamics and slag chemistry as shown in Figure 7. Outotec’s Ausmelt

process allows flexibility in adjusting the oxygen partial pressure and fluxing within the Ausmelt furnace to

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control key process parameters including slag phases present, liquidus temperature, viscosity and slag

conductivity.

Figure 7 - The lead recovery (decreases with increasing pO2 as shown) and % of slag liquid as a function of a

generalized secondary lead feed containing metal, oxides and sulphates, slag composition and oxygen partial

pressure as generated by Factsage™ at 1100oC

SMALL SCALE LEAD BATTERY RECYCLING PROJECTS

A large proportion of secondary lead production is achieved by low capacity processing operations

(less than 30,000 tpa of Pb). These small scale fragmented operations have evolved due to restrictions placed

on the transportation and trade of battery scrap. Small scale lead battery recycling plants traditionally use Short

Rotary Furnaces (SRF) which have limited production capacity of typically 10-15 ktpa of crude lead per

furnace. SRF operate with sodium carbonate (soda) slags which are considered an environmentally hazardous

waste due to the reactivity and leachability of residual elements within the slag. These issues have been strong

drivers for more efficient, cleaner and higher capacity technologies.

Lead acid batteries contain low levels of traditional impurities and gangue components. Silica

contained in the glass separators and calcium or antimony present in the lead-alloy grids are the main impurity

compounds. This consistency in secondary lead battery feed has allowed the Outotec Ausmelt Process to

deviate from the conventional approach of customizing each Ausmelt furnace design to offering ‘off the shelf’

technology packages. By standardizing the Ausmelt furnace design and offering low cost engineering and

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equipment supply through Gravita Exim, Outotec has enabled small scale lead recycling to be done

economically with environmentally friendly technology.

Outotec’s Ausmelt-Gravita lead processing facilities incorporate conventional feed preparation and

delivery, offgas and fume capture and product handling equipment. The main difference is the replacement of

the rotary or blast furnace with an Ausmelt furnace. Targeted toward small scale operations with an annual

production capacity of 15-30 ktpa, the Ausmelt process offers a low cost environmentally friendly processing

route.

The Ausmelt-Gravita Lead Processing Facility illustrated in Figure 8 utilizes smelting and slag

cleaning campaigns. Campaigns are viable for this process because only a relatively small quantity of slag is

produced due to the low levels of gangue materials in battery feeds and low fluxing requirement. The smelting

campaign is a continuous process conducted under mildly reducing conditions. A lead bullion product is

produced with the slag stockpiled for further treatment. The slag cleaning campaign is conducted as a two-stage

batch process. A small volume of bullion is produced with the majority of the lead reporting to an oxide fume

during the second stage reduction. The fume is recycled to the smelting campaign with the final discardable

slag containing 0.5-1.0 wt% Pb. This process has been discussed in detail previously [9].

Figure 8 - Process flowsheet for Outotec Ausmelt Small Scale Lead Smelting Process

ENVIRONMENTAL PERFORMANCE

With increasingly stringent environmental and workplace health and safety regulations the lead

industry is looking for cleaner and more environmentally friendly processing alternatives. Outotec’s Ausmelt

Process exceeds these environmental requirements whilst offering substantial increases in productivity and

throughput.

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Commonly installed to replace old technologies

the Ausmelt Process is considered the ‘Best Available T

• produces a environmentally friendly

• is characterized by a High energy efficiency

• incorporates a Fully sealed furnace ensures effective capture of SO

• facilitates generation of

production;

• can reduce CO2 emissions by

• is Capable of treating toxic

• has the Ability to process up to 100% secondary materials.

Weser Metall Nordenham smelter is a prime example of how

dramatically improve a site’s environmental credentials. This

the existing sinter plant/blast furnace process with an Ausmelt furnace

by 94-99% [7]. Weser Metall have been able to maintain these low

increasing production to more than 40% above the design capacity [

Figure 9 - Emissions at Weser Metall before and after the installation of an Ausmelt furnace

The versatility, economics and environmental benefits of

ensure the Outotec Ausmelt Process

technologies. By customizing the design and operation

flowsheets or augment existing technologies.

requirements has been demonstrated by

0

2000

4000

6000

8000

10000

12000

1995 2006 2008

SO

2E

mis

sio

ns

(t/y

)

SO

to replace old technologies as part of the modernization of existing operations

is considered the ‘Best Available Technology’ since it:

environmentally friendly discardable slag;

High energy efficiency;

Fully sealed furnace ensures effective capture of SO2 and dust emissions

acilitates generation of High strength SO2 off-gas can be sent to an acid plant for sulphuric acid

emissions by utilizing natural gas as a fuel instead of coal;

treating toxic wastes and heavy metal residues; and

Ability to process up to 100% secondary materials.

Weser Metall Nordenham smelter is a prime example of how the Ausmelt Process

dramatically improve a site’s environmental credentials. This modernization project, which involved replacing

the existing sinter plant/blast furnace process with an Ausmelt furnace, reduced SO2 and heavy metal emissions

l have been able to maintain these low SO2 and dust emission levels despite

increasing production to more than 40% above the design capacity [6].

Emissions at Weser Metall before and after the installation of an Ausmelt furnace

CONCLUSION

The versatility, economics and environmental benefits of Outotec’s Ausmelt Process

Process is considered an attractive alternative to existing lead processing

the design and operation, Ausmelt furnaces are easily integrated into traditional

existing technologies. This flexibility to tailor designs according to individual client

demonstrated by the diversity of Outotec’s Ausmelt lead projects.

0

2000

4000

6000

8000

10000

12000

1995 2006 2008 1995 2006 2008

SO2 Emissions Dust Emissions

of existing operations,

and dust emissions;

acid plant for sulphuric acid

can be applied to

involved replacing

and heavy metal emissions

and dust emission levels despite

Emissions at Weser Metall before and after the installation of an Ausmelt furnace

Process combine to

is considered an attractive alternative to existing lead processing

easily integrated into traditional

according to individual client

10000

12000

Du

st E

mis

sio

ns

(kg

/y)

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With the ever increasing push towards processing of secondary lead materials, Outotec and Gravita

Exim have developed a technology package dedicated to the recycling of lead-acid batteries. These complete,

small scale lead battery recycling plants are an environmentally friendly, cost competitive processing option for

projects with a capacity of 15-30 ktpa.

REFERENCES

1. International Lead and Zinc Study Group (www.ilzsg.org).

2. A. Kaye, S. Hughes, R. Matusewicz and M.A. Reuter, “Ausmelt Technology; Developments in Lead

and Zinc Processing, Proceedings Zinc and Lead Metallurgy”, 47th

Annual Conference of

Metallurgists of CIM, Winnipeg, Canada, Ed. L. Centomo, M. Collins, J. Harlamovs, J. Lui, Met Soc,

COM2008, 24-27th

August 2008, Canada, pp. 63-75.

3. G.P. Swayn and E.N. Mounsey, “Ausmelt Technology Versatility: The design and operation of the

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at Tsumeb Smelter, Namibia”, GDMB Conference, 58th Meeting of The Copper Committee,

September 24-25, 1998, Alpbach, Austria, 16p. (preprint).

4. M.B. Kim, W.S. Lee and Y.H. Lee, “QSL Lead Fuming Process Using an Ausmelt Furnace”, Eds. J.E.

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Zinc 2000 Symposium, part of the TMS Fall Extraction & Process Metallurgy Meeting, 22-25th

October 2000 (Pittsburgh, USA), pp. 331-344.

5. C.Y. Choi, “The Role of Lead Smelting at Korea Zinc”, Yazawa International Symposium,

Metallurgical and Materials processing: Principles and Technologies, Vol. II High Temperature

Metals Production, Eds. F. Kongoli, K. Itagaki, C. Yamauchi and H.Y. Sohn, TMS, 2003, pp. 25-39.

6. U. Kerney, “The Nordenham Pb Smelter and its Challenges”, International Science and Technology

Conference: Lead Metallurgy – Achievements and Problems Conference, Legnica, 2010 (preprint).

7. M. Sibony, N. Basin, J. Lecadet, R. Menge and S. Schmidt, “The Lead Bath Smelting Process in

Nordenham, Germany”, J.E. Dutrizac, J.A. Gonzalez, D.M. Henke, S.E. James, A.H.-J. Siegmund

(eds.); Proceedings of the Lead-Zinc 2000 Symposium, part of the TMS Fall Extraction & Process

Metallurgy Meeting, 22-25th October 2000 (Pittsburgh, USA), pp. 319-330.

8. A.D. Besser, V.V. Guriev, M.A. Reuter, R. Matusewicz and A.S. Glinin, “Lead Processing Using TSL

and Electric Furnace Technology”, International Secondary Lead Conference, Venetian Macau Resort

Hotel, Macau, 2009 (preprint).

9. J. Wood, J. Coveney, J. Hoang and M.A. Reuter, “Small-Scale Secondary Lead Processing using

Ausmelt TSL Technology”, International Secondary Lead Conference, Venetian Macau Resort Hotel,

Macau, 2009 (preprint).

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