Research on effects of roasting process and typical impurities on reduction and decomposition process of phosphogypsum
Phosphogypsum is a by-product of industrial wet phosphoric acid production,but because of its high impurity content,it is difficult to utilize,resulting in a huge stockpile.A reduction and decomposition study was conducted using phosphogypsum raw ore and purified phosphogypsum as raw materials,revealing the effects of roasting process and impuri-ties on the high-temperature decomposition of phosphogypsum to prepare CaS.The results showed that the decomposition re-action of phosphogypsum raw ore and purified phosphogypsum tended to equilibrium at 60 min,and the reaction loss on ig-nition could reach 47.77% and 54.44%,respectively.When the product was calcined at 900℃and the reducing agent ratio was above 15% (mass fraction,the same below),there was no residual CaSO4.The best conditions for the conversion of phos-phogypsum into CaS were:the roasting time of 60 min,the roasting temperature of 950℃and the reducing agent ratio of 30% .Under the same conditions,the CaS content of the reduced decomposition products of the purified phosphogypsum group was up to 76.33%,which was higher than that of the phosphogypsum raw ore group under the same conditions(57.37% ).A certain amount of SiO2,NaF and Ca3(PO4)2 were doped in phosphogypsum,and the CaS content of the product could be reduced by 1.41%～12.27%,0.61%～11.48% and 1.85%～4.82%,respectively by combining with the reaction inter-mediate product CaO.
NETL
NSTL
万方数据
