Auriferous wastes from the abandoned arsenic and gold mine in Złoty Stok (Sudetes Mts., SW Poland)

Abstract

The historical arsenic and gold-ore operation at the Złoty Stok mine generated around 1 500 000 tonnes of wastes. The gold-bearing post-flotation tailing dumps, waste slag heaps, mined rock and arsenic roasting spoils (cinders) from mining of metamorphogenic, hydrothermal As-Au deposits have been examined to evaluate their gold grade. The waste material is dominated by calc-silicate skarn, dolomitic marbles, serpentinites and As-Au ore fragments. Sulfides are mainly loellingite, arsenopyrite and pyrrothite with some pyrite, chalcopyrite, sphalerite and galena. In oxidized material, sulfides are rare or absent. Over 1000 samples of post-flotation waste muds and three bulk samples of mined rock spoils were analyzed. Only tailings show high concentrations of Au (0.8-20.1 ppm) and As (1.0-2.6 wt.%). An average contents of other metals (in ppm) are: Cu -- 177.5; Pb -- 212.2; Zn -- 127.5; Ag -- 0.38; Pt -- 0.006; Pd -0.001. Analytical results indicate that concentrations of these elements are very low along profiles, with no obvious relationship between content and depth. Average gold content of 0.3 ppm in waste slags disqualifies this material as a source of gold. The remaining resources of gold in the flotation tailings and waste heaps are estimated at as high as 2370 kg. The main pollutant is As with contents exceeding 52 100 ppm in the mined rock spoils.