Effect of calcium concentration on calcite flotation from apatite using carbonic gas

Abstract

The flotation process currently considered for apatite concentration from the Santa Quitéria phosphate deposit (Brazil), involves bulk flotation of apatite and calcite with anionic collector at pH=10 followed by calcite flotation at pH=5.5, adjusted with H 3 PO 4. Although this concept is efficient from the point of view of separation between apatite and calcite, the intensive use of inorganic acids causes ion accumulation in the process water, especially Ca 2+ and PO 4 2-, which leads to problems in the flotation stage as well as in the environment. CETEM has been studying a process for the separation of carbonate minerals and apatite that involves the use of carbonic gas injected into the bubble generation system of flotation machines instead of inorganic acids. The aim of this study was to evaluate the effect of Ca 2+ ion concentration on the water during the calcite flotation stage of the Santa Quiteria phosphate ore, between 6 mg/L (standard test) and 670 mg/L (maximun concentration) on the flotation performance in terms of P 2 O 5 grade and its loss and the CaO/P 2 O 5 ratio (RCP). The results indicated a reduction in the selectivity on the flotation of calcite from apatite for Ca 2+ concentrations from 6 mg/L to around 285 mg/L. Despite this, the results obtained in this study indicated that the process based on the application of CO 2 for the separation of calcite and apatite may be a technical alternative that causes less impact in flotation performance for the phosphate concentration ores with carbonated gangue.

CO₂ bubble formation on dolomite surface and its influence on surface wettability and flotation of dolomite

“…Consequently, selective separation of apatite from the carbonate gangue minerals is achieved (Wang et al, 2013). Freitas et al (2020) indicated that the process based on the application of CO2 for the separation of calcite and apatite may be a technical alternative that causes less impact on flotation performance for the phosphate concentration ores with carbonated gangue. Saldi et al (2021) investigated the dissolution mechanisms of dolomite at acidic pH by high resolution pH-stat and mixedflow reactor experiments, in conjunction with AFM and TEM observations.…”