No abstract

A solution chemistry approach is developed to study oxalic acid efficiency (OAE) in recovering rare earth (RE) elements from the leachates of weathered clays. The optimal pH for precipitation (approximately 2) to obtain the highest RE recovery with the highest purity is identified experimentally and confirmed by solution chemistry calculations. Applying the solution chemistry approach to three case studies, the cause for a larger oxalic acid consumption than that calculated from stoichiometry of RE oxalate precipitation is identified. A typical OAE of approximately 60 pct was determined with 40 pct of excess oxalic acid consumed by precipitating and complexing non-RE elements while maintaining a low residual RE element concentration. Both solution chemistry calculations and experimental results showed that OAE can be improved by processing leachates of high initial RE concentrations.

No abstract

Phosphate ore is an important raw material for manufacturing fertilizers and phosphorous chemical products. While most of the phosphate resources cannot be directly treated as feed stock due to the low grade of P2O5 and high content of impurities. In order to obtain a qualified phosphate concentrate, the beneficiation of the low-grade phosphate ore is, hence, of great necessity. Many beneficiation techniques can be employed to upgrade the P2O5 grade of phosphate ores based on their characteristics in chemical composition and texture. The flotation process is most widely applied to balance the P2O5 recovery ratio and cost. In this review, the dominant techniques for the beneficiation of phosphate ores are introduced. Moreover, the factors that affect the flotation of phosphate ore, including the properties of mineralogy, flotation reagents (depressants and collectors) and flotation medium, were systematically analyzed.

No abstract