Efficient selective reverse flotation separation of apatite from calcite using a novel depressant malonic acid

The similar surface chemistry of calcium-bearing apatite and calcite makes their separation notoriously challenging, necessitating the use of high-selectivity depressants. This study explored the critical depression effect of malonic acid (MA) in enhancing the selective flotation separation of apatite from calcite. Micro-flotation experimental results showed that MA significantly improved selectivity by effectively suppressing apatite flotation while maintaining the high floatability of calcite. Mixed ore test showed that the grade and recovery of P 2 O 5 in the precipitated products were 27.35 % and 81.29 % at a pH of 9.5 and at an MA dosage of 5 × 10 -4 mol/L. Mechanism study revealed that MA exhibited stronger adsorption on the apatite surface than that on calcite. This preferential adsorption was attributed to the formation of stable chemical bonds between the carboxyl groups of MA and the calcium ion active site on the surface of apatite. MA reduced NaOL adsorption on apatite, thereby enhancing its hydrophilicity and strengthening the selective depression effect. Therefore, MA was an effective depression in the reverse flotation of calcite and apatite. This study is of great significance for the efficient separation and enrichment of phosphate ore resources.