Effect of calcium ion on the separation of rhodochrosite and calcite

The effect of calcium ion on the separation of rhodochrosite and calcite was systematically investigated based on flotation tests, zeta potential measurements, and scanning electron microscopy analysis. The flotation results showed that the separation of rhodochrosite and calcite was inefficient due to rhodochrosite and calcite being similar in many physical and chemical properties, which could make the separation of rhodochrosite from calcite inefficient. The separation of rhodochrosite and calcite can be significantly improved by adding sodium hexa metaphosphate (SH) because SH could depress calcite flotation while it did not bring an impact on rhodochrosite flotation. However, when calcium ion was added into this flotation system, the separation of rhodochrosite and calcite deteriorated as SH also depressed rhodochrosite flotation under this condition. The solution chemical calculation and scanning electron microscopy analysis illustrated that the formation of calcite precipitation coated on the rhodochrosite surface was the main reason because calcium ion increased the depression effect of SH on rhodochrosite. (C) 2017 Brazilian Metallurgical, Materials and Mining Association. Published by Elsevier Editora Ltda.