A clean alternative to smelting or roasting of metal concentrates
Kell process is emissions-free, which is increasingly important as metals concentrates become 'dirtier' with higher levels of deleterious elements. Sulfur and arsenic are safely stabilised in the Kell Process residues as inert compounds therefore avoiding gas phase emissions of SO2 or storage of toxic compounds like As2O3. This is different to many smelters or roasters, where noxious gases are either emitted directly into the atmosphere or require capture by expensive acid plants and baghouses. By enhanced removal of sulfhur at source, Kell also mitigates the environmental risk of Acid Mine Drainage experienced at some minesites.
A cyanide-free process for gold recovery
Kell Process is completely cyanide-free, producing tailings supernatant waters that are close to meeting SANS 241 Drinking Water Guidelines. This eliminates the cyanide risks of wildlife deaths, transportation through communities and operator exposure to HCN gas. There is no need for costly cyanide detoxification processes, cyanide management plans or cyanide code audits.
In contrast, chlorination has been used in water treatment plants for 100 years and is used in most swimming pools today. Kell also removes most reagent consumers upfront, reducing dosing requirements to almost negligible levels.
The London Bullion Market Association will require gold producers and refiners, who account for 90% of global gold production, to provide data on benchmarks including energy usage, water usage, pollution, carbon emissions and health and safety. The London Metal Exchange is introducing similar responsible sourcing guidelines.
A step towards energy reduction and carbon neutrality
Kell represents a step change in progress towards carbon neutrality in the minerals and metals industry. Independent mass-energy balance analysis for a PGM concentrate application showed Kell to have ~12% of the electricity consumption of smelt-refining. This is critical in power-constrained regions, such as South Africa and Zimbabwe, which together produce some 75% of the world's platinum. Lower dependence on electrical grid makes it potentially easier shift to renewables in these regions. Kell shows ~60% of the carbon emissions of smelt-refining. The overall lower net energy consumption improves both project economics and responsible production.