过磷酸钙反应原理再剖析

Further Analysis of the Reaction Principle of Calcium Superphosphate

在硫酸分解磷矿石生产过磷酸钙的反应中,两个分步反应式相加不等于总反应式,说明两个分步反应在理论上不是1∶1的关系。通过理论分析,合理推测两个分步反应是7∶3的关系。以国家标准《过磷酸钙》(GB/T 20413—2017)中优等品为例,第一步反应理论上硫酸分解的磷矿粉约为76.9%,实际上分解达80.8%;第二步反应理论上磷酸分解的磷矿粉约为19.2%,实际约为14.2%;产品中游离磷酸(以P2O5计)质量分数为5%时,残留的磷矿粉约为5.1%。

In the reaction of sulfuric acid decomposition of phosphate ore to produce calcium superphosphate,the sum of two stepwise reaction formulas is not equal to the total reaction formula,which indicates that the two stepwise reactions are not theoretically in a 1∶1 relationship.Through theoretical analysis,it is reasonable to speculate that the two stepwise reactions are in a 7∶3 relationship.Take the national standard Single Superphosphate(GB/T 20413—2017)as an example of superior products,the first step reaction theoretically sulfuric acid decomposition of rock phosphate is about 76.9%,and the actual decomposition is up to 80.8%.The second step reaction theoretically phosphoric acid decomposition of rock phosphate is about 19.2%,and the actual rate is about 14.2%.The free phosphoric acid(as P 2O 5)mass fraction in the product is 5%and the residual rock phosphate is about 5.1%.