磷矿脱镁废液除杂并制备六水磷酸铵镁研究

Purification of de-magging waste liquor of phosphate ore and preparation of magnesium ammonium phosphate hexahydrate

低品位磷矿脱镁后产生大量废液,需循环利用。文章尝试选择性脱除磷矿脱镁废液中的铁、铝、钙等杂质,同时回收镁以制备较高纯度的六水磷酸铵镁。以高含量脱镁液为原料,依次经过陈化除杂、中和除杂、加入氨水,与脱镁液中的镁和磷组分反应制备六水磷酸铵镁。脱镁液经陈化除杂后,用碳酸钠调节溶液pH值为4.0,Fe^(3+)、Al ^(3+)、Ca^(2+)的脱除率分别为99.0%、99.8%、91.2%,Mg^(2+)和H_3PO_4的损失率分别为4.8%、9.2%。制备六水磷酸铵镁的优化工艺参数为:氮镁摩尔比为2.10∶1,反应温度25℃,反应时间20min,搅拌转速200r/min。在该工艺条件下,镁和磷回收率分别为97.60%、52.05%,六水磷酸铵镁纯度为98.0%。

Waste liquid produced from the de‐magging of low grade phosphate ore needs to be treated for reuse .This paper aims to achieve the selective removal of impurities such as Fe3＋ ,Al3＋ ,Ca2＋ in the de‐magging waste liquor ,and the recycling of magnesium to prepare high purity magnesium am‐monium phosphate hexahydrate .High‐level de‐magging liquor of phosphate ore was purified by aging and neutralizing ,then the aqueous ammonia was added to prepare product .When the pH value of the de‐magging liquor was adjusted to 4.0 , the removal rates of Fe3＋ , Al3＋ and Ca2＋ were 99.0% , 99.8% and 91.2% ,respectively ,and the loss rates of Mg2＋ and H3 PO4 were 4.8% and 9.2% ,re‐spectively .The best working conditions for preparing magnesium ammonium phosphate hexahydrate were as follows ：the nitrogen and magnesium were in a mole ratio of 2.10∶1 ,the reaction time was 20 min ,the reaction temperature was 25 ℃ and the stirring speed was 200 r/min .Under such work‐ing conditions ,the recovery rates of magnesium and phosphorus were 97.60% and 52.05% ,respec‐tively ,and the purity of magnesium ammonium phosphate hexahydrate was 98.0% .