Development of a copper arsenate process for Inco's Manitoba Division

CIM Bulletin, Vol. 88, No. 988, 1995

C.L. Stewart, J. Budac, D. Wrana, Inco Limited, Refinery Technical Services, Thompson, Manitoba E. Krause and S.W. Laundry, Inco Limited, J. Roy Gordon Research Laboratory, Mississauga, Ontario

As part of an over-all arsenic management strategy, Inco has developed a novel process that converts a by-product high moisture copper/arsenic sulphide precipitate into a crystalline copper arsenate suitable for the manufacture of wood preservation chemicals. The copper/arsenic sulphide precipitate is atmospherically leached with oxygen and sulphuric acid, producing a crude (blue) copper arsenate precipitate, elemental sulphur, and a copper and nickel containing solution. The blue copper arsenate is dissolved with sulphuric acid, the molar Cu/As ratio is raised to 2, and a crystalline copper arsenate (olivenite) is precipitated by the addition of sodium carbonate. Dissolved copper is recovered using metallic nickel (or matte) and elemental sulphur, to produce a low-moisture (low-arsenic) precipitate suitable for standard nickel-copper processing. The process was successfully piloted at Inco's Manitoba Division between September 1990 and June 1991. The copper arsenate product typically analyzed 43 % Cu and 25 % As, and the moisture content was about 10%.
Mots Clés: Process development, Copper arsenate process, Arsenic management, Inco Manitoba Division.