Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

Even though sodium carbonate is a reagent frequently used in flotation, its role is mostly described as a buffering pH modifier and a pulp dispersant. In the case of scheelite flotation, it has been hinted that sodium carbonate improves both grade and/or recovery but the mechanism itself is ambiguous at best or at least has not been distinctly reported in the literature. Furthermore, the addition of depressants such as sodium silicate or quebracho could be triggering additional mechanisms. Through batch flotation testwork on a skarn scheelite ore with high calcite content, single mineral flotation and contact angle measurements, this article aims at demonstrating that sodium carbonate is a multi-faceted reagent, which serves as a buffering pH modifier, a pulp dispersant precipitating calcium and magnesium ions in suspension, a depressant for calcite and calcium silicates and also a promoter for scheelite. It acts mostly synergistically and partially antagonistically with other depressants, notably sodium silicate and quebracho.