沉淀法去除钼酸钠溶液中磷和硅试验研究

Experimental Study on the Removal of Phosphorus and Silicon from Sodium Molybdate Solution by Precipitation Method

采用沉淀法去除钼酸钠溶液中的杂质磷和硅,研究了沉淀剂种类、溶液pH值、时间、温度等条件对P、Si杂质去除率及除杂过程中Mo损失率的影响,结果表明:以氯化镁为沉淀剂时,除P率最高可达到92.9%,除Si率83.2%,因生成的镁盐呈胶体状态,具有吸附钼酸钠的能力,导致Mo损失率高达4.8%。直接以CaCl_(2)为沉淀剂,钙离子会同时与P、Si、Mo形成沉淀,导致P、Si去除率不理想且Mo损失率高达20.88%。将钼酸钠氧化为过氧钼酸钠后,再采用CaCl_(2)作为沉淀剂,可实现P、Si去除率均高于97.9%,Mo损失率低于0.25%。最佳工艺参数为:料液pH值8~10,沉淀剂用量系数为2,反应温度24~45℃,反应时间90~120 min。

The impurites phosphorus and silicon were removed from sodium molybdate solution by precipitation method,and the effect of precipitant type,pH value of sodium molybdate solution,reaction temperature,reaction time and other conditions on the removal rate of P and Si impurities and the loss rate of Mo during the removal process was explored.The experimental results showed that:when magnesium chloride was used as precipitant,the removal rate of P could reach up to 92.9% and the removal rate of Si was 83.2%,because the generated magnesium salt was in colloidal state,with the ability to adsorb sodium molybdate,resulting in the loss rate of Mo up to 4.8%.When CaCl_(2) was used directly as a precipitant,calcium ions formed precipitates with P,Si and Mo at the same time,resulting in unsatisfactory P and Si removal rates and Mo lost up to 20.88%.With CaCl_(2) as precipitant after oxidizing sodium molybdate to sodium peroxomolybdate,the P and Si removal rate was higher than 97.9% and the loss rate of Mo was lower than 0.25%.The optimum operating parameters were:pH of the feed solution of 8~10,precipitant dosage coefficent of 2,reaction temperature of 24~45℃ and reaction time of 90~120 min.