By-product recovery from copper-nickel bearing duluth gabbro

Abstract

A low-grade copper-nickel mineralization, with an estimated size of 4.6 billion tons and with average analyses of 0.6% copper and 0.2% nickel, occurs in north-eastern Minnesota. In addition to copper, nickel, cobalt, and precious metals, the Duluth gabbro contains magnetite, ilmenite, olivine, anorthite and biotite. The flotation tailings, having already been ground, warrant a closer examination for the recovery and utilization of potential by-products. The residual sulfide minerals and fibrous minerals may also be isolated and treated separately for useful purposes or for disposal in an environmentally acceptable manner. Two flowsheets were developed; one involving preconcentration by low- and high-intensity magnetic separation and another involving preconcentration by tabling. The concentration methods for purifying individual by-product minerals were investigated. From their chemical, physical and mineralogical characteristics, the potential areas of application and marketabilities of each product fraction were examined.