Mechanism of Flotation Separation of Rutile and Hornblende Using SHMP and CMC as Depressants

This study investigates the flotation separation of rutile and hornblende, with particular emphasis on the selective depression mechanism of sodium hexametaphosphate (SHMP) and carboxymethyl cellulose (CMC). Benzohydroxamic acid (BHA) was used as the collector to evaluate its interaction with both minerals in the presence of the depressants. A series of flotation experiments, zeta potential measurements, X-ray photoelectron spectroscopy (XPS), infrared spectroscopy, and nuclear magnetic resonance (NMR) analyses were conducted to examine the behavior of rutile and hornblende under varying pH and reagent conditions. The results show that BHA exhibits significantly stronger adsorption on the rutile surface compared to hornblende. Meanwhile, SHMP and CMC selectively adsorb onto the hornblende surface, effectively suppressing its floatability. SHMP interacts with two forms of Ca²⁺ on the hornblende surface to form calcium hydrogen phosphate (CaHPO₃), while CMC primarily binds with Al³⁺ and Fe³⁺ to form stable metal complexes. These surface products markedly reduce hornblende's flotation performance and enhance the selectivity of the separation process. The findings provide important insights and a theoretical foundation for improving the flotation separation of rutile and hornblende.