Investigations on flotation separation of scheelite from calcite by using a novel depressant: Sodium phytate

In this paper, sodium phytate, a phosphate ester salt rich in phosphate groups, was evaluated as a flotation depressant for selective separation of scheelite from calcite. Its adsorption mechanism on the mineral surface was also investigated through zeta potential and FTIR spectra analysis. The micro flotation results of both single and mixed binary minerals showed that sodium phytate exhibited strong depressant effect on calcite flotation while had little influence on scheelite flotation, when it was added before the collector sodium oleate. Using sodium phytate as depressant improved the flotation separation of scheelite from calcite in the pH range of 7-12. The results of zeta potential measurements and FTIR spectra analysis demonstrated that sodium phytate adsorbed on the calcite surface and hindered the subsequent chemisorption of sodium oleate. The chelating adsorption mainly consisted of the interactions between Ca2+ on calcite surface and the PO tetrahedron in sodium phytate. Sodium phytate did not adsorb on the surface of scheelite and did not hinder the subsequent coverage by the collector sodium oleate. Based on these findings, sodium phytate has the potential to act as an effective depressant in flotation separation of scheelite from calcite.