Processing of copper-nickel ores tailings by the combined method of flotation and low-temperature roasting with ammonium sulfate

Due to the increase in demand for non-ferrous metals and a corresponding increase in production capacity, it is necessary to reconsider the attitude to enrichment waste, especially to tailings dumps, since they represent a significant reservoir of valuable metals. For the processing of flotation tailings represented by finely ground material, it is advisable to use flotation and hydrometallurgical technologies or their combinations. The tailings of copper-nickel ore processing selected from the tailings dam of the processing plant 1 of JSC Kola MMC have been studied. The tailings were enriched in two stages: at the first stage they were floated, and then the resulting froth was subjected to low-temperature roasting in a mixture with ammonium sulfate. The content of the main components in the sample material was, %: 0.218 Ni; 0.075 Cu; 0.015 Co; 13.64 Fe; 0.90 S. The nickel and copper content in the froth flotation product was 0.268% and 0.105%, while 58.16% and 66.75% were extracted, respectively. The froth was mixed with ammonium sulfate in different mass ratios (from 1:1 to 1:4) and roasted at a temperature of 400 oC in a muffle furnace for diffe rent durations from 60 to 240 min. The roasted mixture was leached in heated water with constant stirring for 40 minutes. The maximum extraction of metals was achieved with a roasting duration of 240 minutes and a ratio of raw materials and reagent of 1:3. With the specified parameters, metal extraction was, %: 93.9 Ni; 97.6 Cu; 99.2 Co. The end-to-end extraction of nickel and copper was 54.61% and 65.15%, respectively. The composition of the roasting exhaust gases indicates the possibility of their collection and regeneration of ammonium sulfate.