Recycling of chromium tailings in Bulqiza plant

Chromium mineral processing plant of Bulqiza has begun operation 50 years ago, treating low grade chromium ores grade 12 % to 26 % Cr2O3 and producing chromium concentrates for export. About 1.8 million tons of tailings are stocked in a dam close to the plant. Recycle and enrichment of existing tailings is profitable, because this kind of raw material doesn't need expenses for crushing, grinding and exploitation. The existing plant is in operation for more than 25 years treating existing tailings. Grade of concentrate produced from enrichment of tailings is in the value 38-40 % Cr2O3 and Cr2O3 recovery is in the value 25-33%. The content of particles under 100 µ, the slimes, in raw material is high. In the paper are described the continuous efforts to improve the Cr2O3 recovery. The testing carried out to improve Cr2O3 recovery of tailings enrichment is presented in this paper, as well as analyses of existing process, raw material and products. It is concluded that majority of losses are present in the slimes which are not separated in existing spiral separators and shaking tables. Basing in the study some measures and arrangements in the flowsheet are taken and it is achieved the recovery improvement. In the paper are presented the tests and results of concentration of fine particle fraction, using different methods.