磷石膏矿化CO_(2)制备高纯碳酸钙及产物调控

Preparation of High-purity CaCO_(3) from Phosphogypsum by CO_(2) Mineralization and Product Control

针对CO_(2)减排与磷石膏资源化利用的巨大压力,基于CO_(2)矿化与磷石膏利用过程耦合的学术思想,以磷石膏为原料,研究氯化铵体系中氨水强化磷石膏浸出液制备高纯CaCO_(3)的反应过程。试验过程中系统讨论了不同工艺条件对磷石膏中二水硫酸钙浸出的影响;并就钙离子浸出液在不同条件下所得碳酸化产物的晶型与形貌进行了系统表征。结果表明:在优化的工艺条件下磷石膏中二水硫酸钙的浸出量为0.945×10^(-2)g/mL;所得碳酸化产物为球形球霰石,纯度99.80%,白度99.2%,碳酸化产物的基本性能满足普通工业沉淀碳酸钙标准(HG/T 2226—2010)中的指标要求;在碳酸化过程中通过工艺条件的调控成功实现球霰石和方解石与球霰石混合晶相的可控制备;通过化学分析揭示了磷石膏制备高纯碳酸钙的反应过程。该研究为磷石膏的资源化利用与高纯碳酸钙的制备提供了新的思路。

To meet the demands on low CO_(2) emission and resource utilization of phosphogypsum,this paper is guided by the academic principle of coupling CO_(2) mineralization and phosphogypsum utilization,exploring the reaction of ammonia-strengthened phosphogypsum leaching solution to produce high-purity CaCO_(3)in a NH_(4)Cl-H_(2)O system.The effects of process parameters on the leaching efficiency of CaSO_(4)·2H_(2)O in phosphogypsum were discussed systematically.The crystal phase and morphology of the carbonated product were characterized.The maximum value of dissolved CaSO_(4)·2H_(2)O was 0.945 g/100 mL with the mild reaction conditions.Pure spherical vaterite was produced.The content of calcium carbonate in the product was 99.80%and the whiteness of the product was 99.2%,which satisfied HG/T 2226—2010.The product mixed with cubic calcite and spherical vaterite could be formed by adjusting the reaction conditions.A probable reaction process of CaCO_(3)production and polymorphism transformation was also proposed through chemical analysis of the liquid-solid-gas reaction.This paper provides a new idea for resource utilization of phosphogypsum and preparation of high purity calcium carbonate.