Analyses on the application of components in the phosphogypsum decomposition residue: Based on the study of migration and conversion rules of elements in the purification procedure of CaO

Abstract

Phosphogypsum (PG), which is a solid waste in phosphate fertilizer industry, is harmful to the environment. The pyrogenetic decomposition is mainly used in the utilization of PG, and PG decomposition residue is produced in the decomposition process. In this paper, the migration and conversion rules of elements (Al, Si, P, K, Ca, and Fe) in the purification procedure of CaO in PG decomposition residue was investigated. The acid–base method was used to purify CaO. Content and chemical forms of elements in the purification procedure were analyzed by many characterization methods such as SEM and EDS. And moreover, changes on chemical forms of elements were supported theoretically by some ternary phase diagrams, which were made by the FactSage thermodynamics software. The result showed that, the soluble silicon dioxide and the acid‐insoluble material in PG decomposition residue were effectively removed by using the acid–base method. Meanwhile, impurities separated from CaO and the CaO sample were produced in the experiment, the former can be used to produce the building materials, refractories, insulating materials in various industrial fields, and CaO sample could be used as the filler, building materials, decolorant, etc. © 2017 American Institute of Chemical Engineers Environ Prog, 37: 1020–1030, 2018