Selective leaching of low-grade phosphate ore using a mixture of organic acids

In the present study, the reverse leaching method with the combination of acetic and lactic acid was used for the recovery of phosphate from carbonate phosphate ore, which contained about 10% P2O5. In the experiments carried out on the dissolution, leaching time, temperature, acid concentration, solid/liquid ratio, and particle size distribution were selected as important parameters, and their effects were evaluated. The results showed that the optimization of the leaching condition increased the grade of P2O5 to 29% with a recovery of 90%. The kinetic experiments (time-temperature) in optimal conditions revealed that activation energy for the leaching process was about 24.27 kJ/mol which is an indication of diffusion control processes and the rate of reaction was achieved ⦋1−23α−(1−α)23 ⦌=𝑘0e-24.27/RT.t. Results showed that the application of organic acid leaching would facilitate producing phosphate concentrate from low-grade calcareous phosphate ores.