On the utilization of nickel smelter slags

CIM Bulletin, Vol. 82, No. 921, 1989

Gerhard Heinrich, ORTECH International (formerly Ontario Research Foundation)

The composition and the possible utilization of a slag sample from a nickel smelter operation in the Sudbury district were investigated. The sample containing 0.136% Ni, 0.10% Co and 0.29% Cu could be characterized as afayalite slag with a sulphide bearing glass matrix. While thefayalite contains most of the Co, Ni is enriched within both sulphides and fayalite. Cu is only present in higher amounts in sulphides or metallic droplets. This, as well as the small grain sizes of the mineral phases, inhibits significant enrichment by mechanical methods. However preconcentration is possible by means of magnetic separation. An effective hydrometallurgical approach proved to be oxygen pressure leaching with sulphuric acid. Accordingly, the method proposed for processing the investigated slags is to combine the normal utilization as coarse construction material with pressure leaching of the fines and the ground upgraded magnetic fraction. Besides the recovery of base metals, the leaching process yields fine-grained residues, which, after addition of CaO, will set to a cement-like material, or can be used as a pozzolanic cement colour.

Keywords: Metallurgy, Nickel smelter slags, Metal distribution, Benefic-iation, Pressure leaching, Construction materials