Abstract

Fluorite is usually separated from calcite by froth flotation method using large amounts of sodium silicate

depressant, which can cause trouble in the loss of fluorite and wastewater treatment. In this study, green

and low-cost 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP or H4L) was used as pH-dependent

switch to initially depress fluorite for calcite pre-removal at pH 6.0, and then activate fluorite for further

upgrading fluorite concentrate at pH 8.0. The depressing behavior and mechanism were reported in this

work. H2L2was the dominant form of HEDP, and a stronger chemical adsorption of H2L2

on fluorite hindered the subsequent adsorption of sodium oleate (NaOL), while that of the calcite showed the opposite

result. Two active O atoms in H2L2could well match in interatom distance with two Ca sites on fluorite

to form Ca-H2L complexes. The pH-dependent switch reagent reported here may open a new avenue for

more selective separation among mixed mineral systems

Keywords:

Fluorite

Calcite

Flotation

1-Hydroxyethylidene-1,1-diphosphonic

acid

Sodium oleate

DFT