尼日利亚某中品位磷矿二水法制磷酸实验研究

磷矿湿法加工制取磷酸新装置建设需要根据磷矿性质（化学组成、物相等）的不同进行独立设计,通过在实验室模拟湿法磷酸工业化流程（反应、结晶、过滤）,得到特定磷矿下的制酸工艺参数,可以减少工业化装置试验成本。根据业主委托,采用传统二水法磷矿制酸工艺对尼日利亚某中品位磷矿进行了实验室制酸模拟实验,利用单因素法研究了湿法磷酸工艺主要控制参数包括游离三氧化硫浓度、磷酸浓度、停留时间、温度和料浆液固比对磷矿制酸工艺的影响,得到最适宜的工艺条件：游离三氧化硫质量浓度为25~30 g/L,磷酸纯度（以五氧化二磷质量分数计）为22%~23%,停留时间为4 h,反应温度为75~78 ℃,料浆液固质量比为2.5∶1。在上述条件下,磷矿中五氧化二磷转化率≥93%,五氧化二磷回收率约为90%,料浆的过滤强度（以五氧化二磷计）为8.1 t/（d·m²）。后期跟踪发现,实验室制酸模拟装置得到的实验结果与后期工业化试验结果基本一致。

Experimental study on phosphoric acid produced by dihydrate process from a middle-grade phosphate ore in Nigeria

The construction of a new plant for producing phosphoric acid by wet-process of phosphate rock usually needs to be designed independently according to the different properties of phosphate rock（chemical composition,material equivalence）. By simulating the industrial process of wet-process phosphoric acid （reaction, crystallization and filtration） in laboratory,the process parameters of acid production under specific phosphate rock could be obtained,which would reduce the test cost of industrial unit.According to the customer′s entrustment,the acid production simulation experiment in laboratory of a medium grade phosphate rock from Nigeria was carried out by using the traditional dihydrate process method process,and single factor method was used to study the effects of the main control parameters of WPA process,including free SO₃ concentration, phosphoric acid concentration,residence time,temperature and mass ratio of liquid to solid in slurry.The optimum conditions were as follows：the concentration of free SO₃ was 25~30 g/L,the concentration of phosphoric acid（based on the mass fraction of P₂O₅） was 22%~23%,the residence time was 4 h,the reaction temperature was 75~78 ℃,and the mass ratio of liquid to solid in slurry was 2.5∶1.Under the above conditions,the conversion rate of P₂O₅ in phosphate ore was ≥93%,the yield of P ₂O₅ was about 90%,and the filtration strength of slurry（based on P₂O₅）was 8.1 t/（d·m²）.It was found that in late tracking the experimental results obtained in the laboratory were basically consistent with the test results of late industrialization.