Inorganic Chemicals Industry ›› 2023, Vol. 55 ›› Issue (6): 50-56.doi: 10.19964/j.issn.1006-4990.2022-0496

• Research & Development • Previous Articles     Next Articles

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

WU Yulin1,2(), WU Junhu1,2, YANG Xiushan1,2(), XU Dehua1,2, ZHANG Zhiye1,2   

  1. 1. Ministry of Education Research Center for Comprehensive Utilization and Clean Processing Engineering;of Phosphorus Resources,Chengdu 610065,China
    2. College of Chemical Engineering,Sichuan University,Chengdu 610065,China
  • Received:2022-08-19 Online:2023-06-10 Published:2023-06-16
  • Contact: YANG Xiushan E-mail:3294127065@qq.com;yangxiushan3@163.com

Abstract:

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.

Key words: response surface method, calcium and magnesium nitrate solution, decalcification

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