磷尾矿氨循环法分离钙镁制取氢氧化镁碳酸钙的研究

Study on preparation of magnesium hydroxide and calcium carbonate from phosphorus tailings by ammonia circulation method

为有效分离磷尾矿中的镁、钙、磷,对磷尾矿进行煅烧,其灰分用铵盐铵解,可分离出磷矿并获得氯化钙、氯化镁溶液,铵解过程释放的氨可回收用于下一步的反应。向氯化钙、氯化镁溶液中加入碳酸铵可得到碳酸钙,分离出碳酸钙的溶液再加入氨水可沉淀出氢氧化镁。实验结果表明,采用氨循环法处理煅烧后的磷尾矿,能较好地分离出磷尾矿中的钙、镁、磷元素,制备出碳酸钙和氢氧化镁产品,碳酸钙产品的纯度达到99%、氢氧化镁产品的纯度达到90%。该方法通过氨及二氧化碳的循环利用,既降低了生产成本又减少了对环境的污染,具有极大的推广应用价值。

Calcination was used to separate magnesium,calcium and phosphorus from the phosphorus tailings effectively.Phosphate rock could be separated,and calcium chloride and magnesium chloride solutions were obtained from the reaction of the ash and ammonium salts.The ammonia released from the reaction can be recovered and used in the next reaction.Ammonium carbonate was added into the solution of calcium chloride and magnesium chloride,and then calcium carbonate was obtained.Ammonia water was added into the solution that calcium carbonate was separated to form magnesium hydroxide precipitate.The results showed that calcium,magnesium and phosphorus could be separated well from phosphorus tailings which were calcined by ammonia circulation method.The products of calcium carbonate and hydroxide magnesium could reach more than 99% and 90%(mass fraction),respectively.The production cost and the pollution to the environment could be reduced through the circulation of ammonia and CO_2.