响应曲面法优化硝酸钙镁溶液脱钙工艺研究

Study on optimization of decalcification process of calcium and magnesium nitrate solution by response surface method

针对硝酸预处理磷矿后的钙镁溶液难以利用的问题,提出利用硫酸作为脱钙剂的思路,基于嵌在OLI Studio11.0软件中的混合电解质模型(MSE)进行了热力学分析,采用响应曲面(Box-Behnken)法对硝酸预处理磷矿后的钙镁溶液脱钙工艺进行优化。实验考察了反应温度、反应时间、硫酸用量、硫酸浓度、原料液中氧化钙浓度和镁钙物质的量比等因素对脱钙反应后滤液中镁钙质量比(即镁钙比)的影响。对镁钙比影响较大的因素进行响应曲面实验设计,得出各因素与镁钙比关联的数学模型,并预测最优条件下的镁钙比。响应曲面实验结果表明:在反应温度为40℃,硫酸用量为理论用量的115%,氧化钙质量分数为12%时,滤液中镁钙比最高,此时预测值为16.35,实验平均值为13.52。

In order to solve the problem that the calcium and magnesium solution is challenging to be used after nitric acid pretreatment of phosphate rock,the idea of using sulfuric acid as a decalcification agent was put forward.The thermodynamic analysis was carried out through the mixed electrolyte model(MSE)embedded in OLI Studio 11.0 system.The response surface Box-Behnken method was used to optimize the decalcification process of calcium and magnesium solution after nitric acid pretreatment of phosphate rock.The influences of reaction temperature,reaction time,dosage of sulfuric acid,sulfuric acid concentration,calcium oxide concentration,and molar ratio of magnesium to calcium in raw material on mass ratio of magnesium to calcium m(MgO)/m(CaO)in the filtrate were investigated.The response surface experiment was designed for the factors with significant influence on the m(MgO)/m(CaO),and the mathematical model between each factor and the m(MgO)/m(CaO)was obtained to predict the m(MgO)/m(CaO)under the optimal condition.The results of the response surface experiment showed that when the reaction temperature was 40℃,the sulfuric acid content was 115%of the theoretical content,and calcium oxide mass ratio was 12%,the m(MgO)/m(CaO)in the filtrate was the highest.The predicted value was 16.35,and the experimental value was 13.52.