64
J. Wood et al.
classified as hazardous materials [2]. This has presented significant environmental
and health challenges in the downstream handling, storage and/or disposal of these
waste materials.
In recent years, Outotec has undertaken pilot and commercial-scale development
testwork on the direct bath smelting of zinc sulphide concentrates as a potential alternative processing route with lower operating costs and improved recovery of minor
and precious metal values. The Outotec
® Direct Zinc Smelting (DZS) also eliminates issues around the handling, storage and/or disposal of these waste materials
[3]. Whilst such an approach offers promise for future new zinc production capacity, the existing zinc sulphide treatment processes are expected to continue to serve
for many decades to come. In addition, zinc is also produced from various primary
oxide sources, such as silicate or carbonate ores, where typically direct ore leaching
is employed, with inevitable waste/residue generation.
Whilst the majority of zinc production is currently derived directly from the processing of primary ores and concentrates, with modern zinc smelters now capable of
achieving >97.5% zinc recovery [4], treatment of the above-mentioned zinc-bearing
residues and slags is expected to become increasingly important, particularly as
the minimisation of wastes and closed-loop metals recycling comes ever more into
focus. The recovery of zinc from secondary materials such as steel plant dusts also
represents another important and growing area of interest within the zinc industry.
Despite the development and testing of a range of hydrometallurgical processes for
processing these materials, pyrometallurgical front-end processing of such iron and
zinc-bearing residues, slags, drosses and dusts has been the dominant processing
route prior to electrolytic treatment of the zinc oxide-rich by-products generated.
Traditionally, the box fumer (for liquid slag feed) and Waelz kiln (for solid feed) have
been the pyrometallurgical zinc fuming workhorses and have been employed over
many decades. In more recent years, a range of alternative pyrometallurgical fuming
processes have been adopted, such as Top Submerged Lance (TSL), side-blowing
and plasma technologies. These can offer benefits such as improved efficiencies,
higher minor and precious metal recoveries and generation of a stable slag, suitable
for discard or use in construction applications.
Outotec Ausmelt Process Development
Outotec is a leading supplier of technology solutions for the metal production industries, with a long history of developing innovative equipment and processes with
strong environmental credentials [5]. This has been enabled by investing in its own
research and development facilities as well as through co-operative programs with
both its customers and academic institutions. These programs typically employ a
combination of theoretical analysis backed up by physical testwork. The use of pilot
plant testing has been integral to the successful commercialisation of many processes,
including the Ausmelt process. Today, Outotec maintains its own Ausmelt pilot plant
J. Wood et al.
classified as hazardous materials [2]. This has presented significant environmental
and health challenges in the downstream handling, storage and/or disposal of these
waste materials.
In recent years, Outotec has undertaken pilot and commercial-scale development
testwork on the direct bath smelting of zinc sulphide concentrates as a potential alternative processing route with lower operating costs and improved recovery of minor
and precious metal values. The Outotec
® Direct Zinc Smelting (DZS) also eliminates issues around the handling, storage and/or disposal of these waste materials
[3]. Whilst such an approach offers promise for future new zinc production capacity, the existing zinc sulphide treatment processes are expected to continue to serve
for many decades to come. In addition, zinc is also produced from various primary
oxide sources, such as silicate or carbonate ores, where typically direct ore leaching
is employed, with inevitable waste/residue generation.
Whilst the majority of zinc production is currently derived directly from the processing of primary ores and concentrates, with modern zinc smelters now capable of
achieving >97.5% zinc recovery [4], treatment of the above-mentioned zinc-bearing
residues and slags is expected to become increasingly important, particularly as
the minimisation of wastes and closed-loop metals recycling comes ever more into
focus. The recovery of zinc from secondary materials such as steel plant dusts also
represents another important and growing area of interest within the zinc industry.
Despite the development and testing of a range of hydrometallurgical processes for
processing these materials, pyrometallurgical front-end processing of such iron and
zinc-bearing residues, slags, drosses and dusts has been the dominant processing
route prior to electrolytic treatment of the zinc oxide-rich by-products generated.
Traditionally, the box fumer (for liquid slag feed) and Waelz kiln (for solid feed) have
been the pyrometallurgical zinc fuming workhorses and have been employed over
many decades. In more recent years, a range of alternative pyrometallurgical fuming
processes have been adopted, such as Top Submerged Lance (TSL), side-blowing
and plasma technologies. These can offer benefits such as improved efficiencies,
higher minor and precious metal recoveries and generation of a stable slag, suitable
for discard or use in construction applications.
Outotec Ausmelt Process Development
Outotec is a leading supplier of technology solutions for the metal production industries, with a long history of developing innovative equipment and processes with
strong environmental credentials [5]. This has been enabled by investing in its own
research and development facilities as well as through co-operative programs with
both its customers and academic institutions. These programs typically employ a
combination of theoretical analysis backed up by physical testwork. The use of pilot
plant testing has been integral to the successful commercialisation of many processes,
including the Ausmelt process. Today, Outotec maintains its own Ausmelt pilot plant