Selective inhibition mechanism of PBTCA on flotation separation of magnesite from calcite

This research focused on the inhibition effect and mechanism of a selective depressant PBTCA (2-phosphonobutane-1,2,4-tricarboxylic acid) on flotation separation of magnesite from calcite. The inhibition effect of PBTCA was investigated through micro-flotation tests, and the results showed that PBTCA presented selective inhibition effect on calcite in sodium oleate (NaOL) system. The inhibition mechanism of PBTCA was analyzed by contact angle measurements, zeta potential analysis and X-ray photoelectron spectroscopy (XPS) analysis. The results of contact angle measurements indicated that PBTCA could increase the hydrophilicity of calcite surface while magnesite surface still maintained hydrophobicity with PBTCA and NaOL. Zeta potential measurements results indicated that the adsorption of PBTCA on calcite surface was stronger than magnesite, and NaOL could further adsorb on magnesite surface even PBTCA existed. Furthermore, XPS results confirmed the stronger adsorption between PBTCA and calcite, which could be attributed to the interaction between phosphonyl (–PO3H2) structure of PBTCA and calcium ions on calcite surface. [Display omitted] •PBTCA was firstly used as a depressant in magnesite/calcite flotation.•PBTCA could selectively inhibit calcite but not magnesite.•The inhibition mechanism of PBTCA was studied.•The stronger interaction of –PO3H2 and Ca2+ was the main cause of inhibition.