The Versatility of Outotec's Ausmelt Process for Lead Production
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Transcript of The Versatility of Outotec's Ausmelt Process for Lead Production
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: [email protected])
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)
449
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
Ausmelt lead smelter and the subsequent development of the unit to successfully produce copper matte
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.
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. 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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