A novel process for the separation and recovery of phosphorus and rare earth elements from associated rare earth phosphate ores

Associated rare earth phosphate ore constitutes a vital strategic resource. However, several challenges are linked to current mainstream wet processing methods, such as the separation of phosphorus elements from rare earth elements (REEs) and resultant environmental pollution. Vacuum reduction technology presents distinct advantages due to its high metal reduction rate and absence of triple waste generation. This study investigates an innovative approach for the separation and recovery of phosphorus and REEs though vacuum carbon thermal reduction of associated rare earth phosphate ores. Theoretical calculations show that at 0.1 Pa and a carbon allocation factor of 1.14, the initial temperature at which Ca5(PO4)3F was reduced to P2 is 800 °C. Temperatures exceeding 1,300 °C led to a small amount of RE3+ being reduced to gaseous REO. This temperature range, spanning 800–1,300 °C, was determined as optimal for the separation of phosphorus and REEs. The experimental results confirmed complete phosphorus and REEs separation at 1,300 °C, with 98.61 % phosphorus volatilization and 97.68 % REEs recovery. The results of the hydrochloric acid leaching reduction specimens showed that the REEs leaching rate was 84.11 %. Adjusting acid leach solution to pH 4.3 with sodium carbonate yielded 93.11 % REEs precipitation, 5.83 % rare earth grade, and 77.64 % total REEs recovery. This study advances condensed phosphorus and REEs enrichment, with implications for phosphoric acid and rare earth industries, thus providing a new direction for comprehensive recovery and utilization of associated rare earth phosphate ores.