用纳米比亚中品位磷矿制备磷酸的实验研究

Preparation of Phosphoric Acid from Namibia Medium Grade Phosphate Rock

本文采用半水-二水法湿法磷酸生产工艺,开展了用纳米比亚中品位磷矿制备磷酸的实验研究。在半水反应工段,得到了P_(2)O_(5)浓度为38.0%的浓磷酸,半水磷石膏滤饼不经洗涤,直接进入二水转化工段。与单独采用半水法生产湿法磷酸的工艺不同,半水-二水法的生产工艺中,磷矿分解过程的控制指标是得到较好的半水物晶体,以提高过滤强度。半水部分的P_(2)O_(5)转化率较低的问题,可以在二水再结晶转化的过程中加以解决。采用二水再结晶转化流程,磷矿中的P_(2)O_(5)转化率从88%提高到97.5%,总P_(2)O_(5)回收率在93%以上。

An experimental study on the preparation of phosphoric acid from Namibia’s medium grade phosphate rock was carried out by the production process of hemihydrate dihydrate wet process phosphoric acid.In the hemihydrate reaction part,concentrated phosphoric acid with P_(2)O_(5) concentration of 38.0% was obtained.The RG hemihydrate phosphogypsum filter cake directly entered the secondary water conversion section without washing.Different from the process of producing wet process phosphoric acid by hemihydrate method,in the production process of hemihydrate dihydrate method,the control index of phosphate rock decomposition process was to obtain better hemihydrate crystals in order to improve the filtration strength.The conversion rate of P_(2)O_(5) in hemihydrate was low,which could be solved in the process of recrystallization and conversion of dihydrate.By the process of secondary water recrystallization conversion,the P_(2)O_(5) conversion rate in phosphate rock was increased from 88% to 97.5%,and the total P_(2)O_(5) recovery rate was more than 93%.