以贵州开阳磷矿粉为原料,研究了磷酸化学浸提法脱镁的最佳工艺条件,即脱镁剂稀磷酸溶液P2O5质量分数15%、pH值2.0、反应温度55℃、反应时间2.5h、液固比2.0。在该条件下,Mg脱除率75.67%,P2O5损失率2.33%,镁磷比2.03%。同时研究了磷矿脱镁液氨水沉淀法制备六水磷酸铵镁的最佳工艺条件,即pH值8.5、反应温度40℃、反应时间60min。在该条件下,P2O5回收率99.31%,Mg回收率87.70%。 Taking Kaiyang phosphate rock as raw material, the optimum technological conditions of magnesium removal by phosphoric acid chemical leaching were studied, that is, the content of P2O5 was 15%, the pH value was 2.0, the reaction temperature was 55 ℃ and the reaction time was 2.5 h, liquid to solid ratio of 2.0. Under this condition, the removal rate of Mg is 75.67%, the loss rate of P2O5 is 2.33% and the ratio of magnesium to phosphorus is 2.03%. At the same time, the optimum technological conditions for the preparation of ammonium magnesium phosphate hexahydrate by ammonium sulfate precipitation of magnesium phosphate solution were studied, that is, pH 8.5, reaction temperature 40 ℃ and reaction time 60min. Under this condition, the recovery rate of P2O5 was 99.31% and the recovery rate of Mg was 87.70%.