利用萃余磷酸制取重过磷酸钙的工艺条件研究

利用湿法磷酸净化副产的萃余磷酸为原料分解磷矿，采用化成法制取重过磷酸钙（以下简称重钙）。实验中采用单因素法考察了磷酸浓度、反应温度、磷矿粉细度、磷酸含固量和酸矿比对磷矿分解率与重钙产品品质的影响，实验得出的最佳工艺条件为：磷酸质量分数≥43%，含固量（质量分数）≤8%，酸矿比［m（P2O5）酸/m（P2O5）矿］为2.6，反应温度为45～65 ℃，反应时间为2～3 min，将产物继续化成20～25 min，化成温度为80 ℃，然后进行熟化，熟化温度为55 ℃，熟化时间为8～14 d，在此工艺条件下重钙产品达到了一等品的标准。同时本研究还可以解决萃余磷酸的存放问题，使萃余磷酸得到了综合利用，具有较大的经济和社会效益。

Research on preparation process of tripe superphosphate from raffinate phosphoric acid

Tripe superphosphate（TSP） was manufactured by den process，with phosphorite and raffinate phosphoric acid by- produced from wet process phosphoric acid purification process as the raw material.The effects of phosphoric acid concentra- tion，reaction temperature，phosphorite fineness，solid content of phosphoric acid，and the ratio of acid to phosphorite mineral on decomposition rate and product quality of TSP were investigated by single factor experiment.The optimal conditions were obtained as follows: phosphoric acid concentration was at least 43%，solid content（mass fraction）was less than 8%，the ratio of acid to mineral［m（P2O5）acid/m（P2O5）mineral］was 2.6，reaction temperature was at 45～65 ℃，reaction time was 2～ 3 min，den process time was 20～25 min and the den temperature was 80℃，ripening temperature was 55 ℃，and ripening time was 8～14 d.Under these conditions，TSP could meet the standard of first class products.Meanwhile，phosphoric acid sludge and raffinate were utilized comprehensively，so that the storage problem of raffinate phosphoric acid would be solved，which would bring significant economic and social benefits.