Chemistry of benefication products from Altermark, northern Norway.

Abstract

The chemistry of products from benefication tests of Altermark talc made by Pluss-Staufer AG is described. The earlier conclusions that the ore is very pure when it comes to elements with potential risks to health have been confirmed, although minor amounts of Cr and Ni are present. Of major importance is the composition of talc-products from the Nakkan deposits, which is currently being investigated, and the current mine as well as their relationship to chemical composition of the crude ore. Pluss Stauffer has succeeded in making pure talc-products of high quality of the Altermark talc. Some slightly different results were obtained from the Nakkan ore, with respect to recovery and whiteness, which were also element characteristics of products, but with some small variations in the content of Ni and Cr. The content of Ni and Cr are lowest in the Nakkan product. Estimation of mineralogy from the chemical data, indicate that the amount of talc in the best products reaches around 95%, the remainder being carbonates and chlorite. In the present report a model is presented which explains the variations in the Ni and Cr contents in relation to the grade of talc-carbonate alteration. With progressive alteration of serpentinite to talc-carbonate the magnetite and Ni-bearing sulphides disappear. The Fe from magnetite moves into carbonate, talc and chlorite, while Ni from the sulphides moves into talc, and to a limited extent, into carbonate. Chromium, which is abundant in magnetite, moves primarily into chlorite, but to a much more limited extent also into talc.