136
D. Dreisinger et al.
recovery. The concentrate was shipped off-site to smelters and the off-site shipment incurred substantial environmental monitoring, was considered high risk, and
transport and smelting costs were high. Environmental concerns related to off-site
shipment of concentrate have historically led to extended shutdowns while these
issues were being addressed.
This scenario set the scene for the development of a hydrometallurgical treatment route to produce lead metal on-site, to improve the project cash costs and to
conclusively address the off-site environmental issues.
LeadFX secured rights to a hydrometallurgical process for lead recovery from
InCoR Technologies (InCoR), who had earlier secured the process rights from BASF
SE and the University of British Columbia (UBC). The technology uses methane
sulphonic acid (MSA), produced by BASF, as a lixiviant for cerussite dissolution.
The process also employs an anglesite conversion step and recovers the lead by
electrowinning to produce lead cathode which is then melted and cast into ingot for
sale.
A considerable batch, pilot plant and demonstration plant test work programme
were undertaken, predominantly with ALS Global Metallurgical Services at their
Balcatta facility in Western Australia, to support the flowsheet and project development. The test programme addressed improving the flotation performance in concert with developing the hydrometallurgical flowsheet. Significant modifications in
the flotation reagent regime and flowsheet configuration resulted in improved flotation recovery and concentrate grade compared to historical data. These results were
achievable even at lower head grades of 4–5% Pb. The increased recoveries in turn
led to a considerable increase in the reserve base for the project, increasing the project
life from ~4.5 years (concentrate shipment) to at least 17 years (on-site lead ingot
production).
The hydrometallurgical treatment route was developed through batch and pilot
plant test work to take the lead concentrate through to produce lead metal, using the
concept flowsheet developed by UBC as a basis. The results of the more detailed test
work lead to a significant evolution of the flowsheet, which is discussed below, and
led to a treatment process capable of recovering 98% of the contained lead in concentrate. The treatment of the concentrate posed significant solid/liquid separation issues
which were successfully bypassed and eliminated in the flowsheet development.
The majority of the lead in the concentrate is readily dissolved by rapid leaching
with MSA and the flowsheet evolution centered on liquid/solids separation issues and
recovering the lead from the minor lead minerals present in the feed. In particular
secondary lead sulphide, produced by the sulphidation process used in flotation,
needed to be recovered so the overall process now successfully treats both sulphide
and oxide lead minerals.
D. Dreisinger et al.
recovery. The concentrate was shipped off-site to smelters and the off-site shipment incurred substantial environmental monitoring, was considered high risk, and
transport and smelting costs were high. Environmental concerns related to off-site
shipment of concentrate have historically led to extended shutdowns while these
issues were being addressed.
This scenario set the scene for the development of a hydrometallurgical treatment route to produce lead metal on-site, to improve the project cash costs and to
conclusively address the off-site environmental issues.
LeadFX secured rights to a hydrometallurgical process for lead recovery from
InCoR Technologies (InCoR), who had earlier secured the process rights from BASF
SE and the University of British Columbia (UBC). The technology uses methane
sulphonic acid (MSA), produced by BASF, as a lixiviant for cerussite dissolution.
The process also employs an anglesite conversion step and recovers the lead by
electrowinning to produce lead cathode which is then melted and cast into ingot for
sale.
A considerable batch, pilot plant and demonstration plant test work programme
were undertaken, predominantly with ALS Global Metallurgical Services at their
Balcatta facility in Western Australia, to support the flowsheet and project development. The test programme addressed improving the flotation performance in concert with developing the hydrometallurgical flowsheet. Significant modifications in
the flotation reagent regime and flowsheet configuration resulted in improved flotation recovery and concentrate grade compared to historical data. These results were
achievable even at lower head grades of 4–5% Pb. The increased recoveries in turn
led to a considerable increase in the reserve base for the project, increasing the project
life from ~4.5 years (concentrate shipment) to at least 17 years (on-site lead ingot
production).
The hydrometallurgical treatment route was developed through batch and pilot
plant test work to take the lead concentrate through to produce lead metal, using the
concept flowsheet developed by UBC as a basis. The results of the more detailed test
work lead to a significant evolution of the flowsheet, which is discussed below, and
led to a treatment process capable of recovering 98% of the contained lead in concentrate. The treatment of the concentrate posed significant solid/liquid separation issues
which were successfully bypassed and eliminated in the flowsheet development.
The majority of the lead in the concentrate is readily dissolved by rapid leaching
with MSA and the flowsheet evolution centered on liquid/solids separation issues and
recovering the lead from the minor lead minerals present in the feed. In particular
secondary lead sulphide, produced by the sulphidation process used in flotation,
needed to be recovered so the overall process now successfully treats both sulphide
and oxide lead minerals.