Research on the melting characteristics during the reaction process of phosphogypsum and calcium sulfide

To explore the dominant factors that cause the problems such as coating formation,ring formation,bonding and blocking,etc.,in rotary kiln used in the industrial production of sulfuric acid,the melting characteristics of decomposition process of phosphogypsum are investigated.With phosphogypsum and calcium sulfide as raw materials,ash melting point measuring instrument is used to study the effects of additives and reaction atmosphere on the melting softening temperature(ST) in the CaSO4 and CaS solid-solid reaction.The results show that,the effective additive of increasing the melting softening temperature during the decomposition of phosphogypsum are kaolin and mixed atmosphere containing SO2,CO2 and N2,respectively.The additives such as SiO2,AlPO4,FePO4·2H2O,Na2SiF6,and so on,play a role in fluxing action.