Combined inhibitors of Fe3+, Cu2+ or Al3+ and sodium silicate on the flotation of fluorite and quartz

Fluorite ore, as an essential raw material in the fluorinated chemical industry, required effective separation and purification. The removal of impurities such as quartz becomes the key point in fluorite flotation. In this work, the fluorite flotation tests via adding the different mass ratios of metal ions (Fe3+, Cu2+, Al3+) and sodium silicate (SS) as a combined inhibitor, were carried out on a laboratory scale. Results indicated that when the mass ratio of SS to Fe3+, Cu2+, and Al3+ was 3:1, 1:1, and 3:1, the fluorite recovery reached 75.01%, 83.56%, and 81.84%, while quartz recovery was only 9.20%, 6.09%, and 4.76%, respectively. In addition, the action mechanisms of the combined inhibitors were investigated and evaluated in-depth. Compared with the single inhibitor of SS, the results of contact angle measurements, Zeta potential measurement, and Fourier transform infrared spectroscopy showed that the combined inhibitor could attenuate the activation of Ca2+ on quartz, and therefore to avoid the quartz mismatching into fluorite concentrates. Therefore, it provides an alternative separation method to realize high-efficient flotation of the fluorite and quartz with the presence of metal ion inhibitors.