Selective co-adsorption of a novel mixed collector onto magnesite surface to improve the flotation separation of magnesite from dolomite

Recovery phosphate and ammonium from aqueous solution by the process of electrochemically decomposing dolomite

The cost-effective recovery of phosphate is of great significance to the mitigation of phosphorus resource depletion crisis. The electrochemical-decomposition of dolomite was developed to recover phosphate and ammonium from aqueous solution. The dolomite ore is mainly composed of CaMg(CO₃)₂ (53.73%), CaCO₃ (28.93%) and SiO₂ (16.59%). The continuous release of Mg²⁺ and Ca²⁺ were achieved by electrochemically decomposing dolomite ore, accompanied by the generation of base solution (9.0-10.5). The main factors affecting the recovery performance of phosphate (PO₄-P) and ammonium (NH₄-N) are current, initial concentration of PO₄-P and NH₄-N, initial pH of feed solution and feed rate. For a 30-d operation, the recovery rate of PO₄-P was maintained at 90-97% and that of NH₄-N at 50-60% under optimized operating conditions. The recovered product had low water solubility but high citric-acid-soluble, and was proposed as a slow-release fertilizer for crops. The proposed process as a simple, effective and green route may serve as a new strategy for recovering PO₄-P and NH₄-N from wastewaters.

Influence of Sodium Phosphate Salts with Different Chain Length on the Flotation Behavior of Magnesite and Dolomite

This paper analyzes the influence of sodium phosphate salts with different chain lengths as depressants on the flotation behavior of magnesite and dolomite through single mineral flotation test, contact angle test, and theoretical analysis. Flotation tests show that depressants should be added for the flotation separation of magnesite and dolomite. The inhibition of sodium phosphate salts on dolomite is significantly stronger than magnesite, and the flotation difference of minerals is affected by the chain length of phosphate depressants. The order of flotation separation enhancement of different sodium phosphate depressants is sodium hexametaphosphate ≈ sodium tetrapolyphosphate > sodium tripolyphosphate > sodium pyrophosphate. This result could also be supported by the contact angle measurement.