【摘要】 磷酸铵、氨水和氟化钙混合高压浸出白钨矿生成氟磷酸钙,并一步得到钨酸铵溶液,避免了传统氢氧化钠分解-离子交换转型工艺带来的废水污染,是实现白钨绿色冶炼的有效途径.氟化钙作为固体氟源,其在浸出过程的溶解一定程度上决定了白钨的分解效果.为此,研究了氟化钙在磷酸铵-氨水混合溶液中的溶解行为.考察了磷酸铵用量、氨水浓度、温度、保温时间和液固比对氟化钙浸出率的影响.实验结果表明:随磷酸铵用量和保温时间的增大,氟化钙浸出率逐渐增大;随氨水浓度、温度和液固比的增大,氟化钙浸出率先增大而减小.当磷酸铵用量为理论量的25倍、氨水浓度为3 mol/L、温度为180℃、液固比(指质量比,下同)为50∶1以及保温时间为180 min时,氟化钙浸出率达到91.1%.更多还原

【Abstract】 Ammonium phosphate, ammonia solution and calcium fluoride are mixed to leach scheelite under high pressure to produce fluorapatite, and ammonium tungstate solution was obtained directly, which was an effective way to realize green smelting of scheelite,avoiding wastewater pollution caused by traditional sodium hydroxide decomposition-ion exchange transformation process. As a solid fluorine source, the dissolution of calcium fluoride in the leaching process was closely related to decomposition effect of scheelite. Therefore, the dissolution behavior of calcium fluoride in ammonium phosphate-ammonia mixed solution was studied. The effects of ammonium phosphate dosage, ammonia solution concentration, temperature, holding time and liquidsolid ratio on leaching rate of calcium fluoride were investigated. Results showed that the leaching rate of calcium fluoride increased with the increase of ammonium phosphate dosage and holding time, while, it increased firstly and then decreased with the increase of ammonia solution concentration, temperature and liquid-solid ratio. The leaching rate of calcium fluoride reached 91.1% when the dosage of ammonium phosphate was 25 times as much as the theoretical amount, the concentration of ammonia solution was 3 mol/L,the temperature was 180 ℃, the liquid-solid ratio was 50∶1 and the holding time was 180 min.更多还原