Influence of SHMP Concentration on Rutile Flotation in BHA System: Guiding the Separation of Rutile and Hornblende

Sodium hexametaphosphate (SHMP) is a common depressant used in rutile flotation, especially for silicate gangue minerals such as amphibole. However, the experiment found that in the benzyl hydroxamic acid (BHA) system, SHMP of small concentrations affected the flotation recovery of rutile. In this work, the influence mechanism of SHMP concentration on the flotation of rutile in the BHA system was studied by flotation test, adsorption capacity determination, ζ potential determination, infrared spectrum analysis, and X-ray photoelectron spectroscopy (XPS) analysis. The test results show that in the BHA system, SHMP chemically adsorbs on the rutile surface, hindering the effect of BHA on the rutile surface, and hydrolyzes in the pulp to form hydrophilic colloids. When the concentration of BHA is 40 mg/L and that of SHMP is 6 mg/L, the effect of SHMP is the most obvious. However, with the increase of SHMP concentration to 8-10 mg/L, its effect on the recovery of rutile became very weak. When the concentration of SHMP is lower than 6 mg/L, the SHMP anion-metaphosphate ion (SHMP^-) interacts with the hydrophilic colloidal particles on the surface of rutile, which affects the combination of BHA and the active sites on the surface of rutile, thus affecting the recovery of rutile. When the concentration of SHMP continues to increase, the SHMP^- adsorbed on the rutile surface is removed from the rutile surface due to the charge repulsion and the competitive adsorption of BHA.