Flotation separation of scheelite from calcite using baicalin as a depressant

Abstract

In this study, the depressive effect and mechanism of baicalin (BAI), a flavonoid, in the flotation separation of scheelite and calcite was investigated. A series of surface analysis techniques were used to explain the selective depression mechanism of BAI on the calcite in flotation. The outcomes of the microflotation tests clearly demonstrated the selective depression of BAI on calcite in flotation separation. Under a pH of 9, dosage regimen of 20 mg/L BAI and 50 mg/L NaOL, the recovery rates were 82.24% for scheelite and 4.12% for calcite. Findings derived from contact angle measurements, adsorption tests, and zeta potential measurements that baicalin impeded the subsequent adsorption of sodium oleate onto calcite after interaction but had a lesser effect on scheelite. Furthermore, analysis of the FTIR spectra and XPS results revealed the selective adsorption of baicalin on the surface of calcite. The dominant component on the calcite surface was mainly positively charged calcium species, the hydroxyl group within the baicalin molecule could chelate react with the calcium plasmonic dots on the calcite surface, it resulting in a stronger chemisorption phenomenon on the calcite surface. But the dominant component on the scheelite surface was mainly negatively charged tungstate, it has less effect on its floatability. Under the inhibiting effect of BAI, the floatability difference between scheelite and calcite becomes larger, and finally achieving the flotation separation of the two minerals. Therefore, BAI is an environmentally friendly and efficient depressant.