Minerals Engineering, Vol.131, 146-153, 2019
An investigation of the mechanism of using iron chelate as a collector during scheelite flotation
The use of lead ions in combination with benzohydroxamic acid (BHA) as a collector is commonly adopted to modify the surface properties of tungsten minerals to improve their floatability. However, the dosage of lead ions is difficult to precisely control, causing excess dissociative lead ions in the pulp that can consume BHA and lead to a reduction of flotation efficiency. This paper develops a new iron chelate reagent that consists of ferric chloride (FeCl3) and BHA by changing the conventional dosing sequence of FeCl3. The individual mineral flotation results showed that the Fe-BHA chelate had a better scheelite collecting ability compared to the Pb-BHA or Al-BHA chelate, and it proved to be superior to the BHA using Fe3+, Pb2+, and Al3+ as activators. The Fe-BHA chelate also showed a good separation performance in the artificially mixed mineral flotation tests of scheelite and calcite at pH 8.0, as well as of scheelite and fluorite at pH 11.0. The zeta potential measurement results showed that the Fe-BHA chelate altered the zeta potential of scheelite to more positive values compared to the BHA with Fe3+ ions as activators at pH 8.0-12.0. The FTIR analysis verified the chemical adsorption of the Fe BHA chelate on the scheelite surface. By conducting Freundlich fitting of the adsorption isotherm of the Fe-BHA chelate on scheelite, the adsorption of Fe-BHA is demonstrated to be an ion-molecule co-adsorption. The potential of the Fe-BHA chelate as a scheelite collector is also proven.