二氧化硅和高岭土杂质对硫铁矿分解磷石膏的影响

Effect of SiO_2 and Kaolin Impurities on Decomposition of Phosphogypsum by Iron Pyrite

针对磷石膏资源化利用存在问题,提出了一种用硫铁矿分解磷石膏的方法.为了实现该工艺的工业化利用,探究了磷石膏内二氧化硅和高岭土杂质对分解过程的影响.利用Factsage7.0热力学软件,计算了Fe S-Ca SO4体系在加入二氧化硅或高岭土后的平衡相图,探讨了加入杂质后可能发生的副反应.进行了杂质对分解过程影响的实验,并对产品进行SO3分析及XRD表征.研究结果表明,Si O2或高岭土的加入使得Fe S和Ca SO4在低温区就能发生反应,提高了反应体系的脱硫率,促进了硫酸钙的分解,并且杂质含量越高,硫酸钙分解率越高.该研究结果有利于硫铁矿还原分解磷石膏制备硫酸工艺的推广应用.

A new method of decomposing phosphogypsum （PG） with pyrite was proposed for solving the problem of PG resource utilization. And with the purpose of realizing the industrialization of the method, the effect of SiO2 and Kaolin impurities on the decomposition process of PG was explored. Equilibrium phase diagram of FeS-CaSO4 system was calculated with adding silicon dioxide or Kaolin by using thermodynamic calculation software of Factsage7.0. The possible existing side reactions were discussed considering the influence of impurities on the reaction system. Then experiments of influence of impurities on the decomposition process were conducted. And the analysis of SO3 and X-ray Diffraction of products were carried out. The results show that CaSO4 can react with FeS in lower temperature region through adding SiO2 or Kaolin as impurities. The desulfurization rate of reaction system is improved, and the decomposition rate of CaSO4 also increases with impurities contents increasing. Thus, the study results are contributed to the application of the sulfuric acid production process of PG decomposition by iron pyrite.