Stillwater Mining Company is a producer of platinum group metals (PGM), and has increased production three-fold from their mining, processing, smelting, and refining facility in Montana.

The existing base metal refinery (BMR) produced two products for further processing, namely, a PGM-rich residue, which is toll refined, and a base metal liquid stream which is processed by others.

Stillwater approached Hatch to complete test-work, and design process circuits which would produce copper cathode, nickel sulphate and cobalt. After preliminary study, the economics of the project showed that production of all the desired products was not feasible due to cost and that the project should be carried out in phases.

Phase 1 implemented copper electrowinning while Phase 2 included a copper dissolve circuit and a selenium/tellurium removal circuit. Phase 3 may be included in the future for the production of nickel/cobalt sulphate crystals.

Scope of Services

• Test-work design and execution
• Process development and design
• Basic and detailed engineering
• Construction supervision and assistance
• Commissioning
• Operating manuals

Project Highlights

• Three-fold production increase
• Budget constraints
• Multi-phase construction