Abstract
Recently, many kinds of aversive substances (chlorides, alkalies, sulfurs and heavy metals) are brought into cement manufacturing process as raw materials, and they are usually removed by chlorine bypass system from cement kiln-preheater, which is called as "K powder". Since "K powder" still contains cement constituents, its character has been expected to be clarified for the recycling.
In this study, we carried out the analyses of "K powder" to identify its minor minerals by various selective dissolution techniques, and created a set of equations estimating the mineral composition of "K powder" from its chemical composition. As a result, we confirmed that K powder was composed from 19 or more minor minerals such as SiO2, 2CaO·SiO2, 2CaO·Al2O3·SiO2, 2CaO·(Al, Fe)2O3, Ca3(SO3)2SO4, CaS, KCl·2PbCl2, CaMg(CO3)2 and K3Na(SO4)2, etc., and created a set of equations by norative calculation assuming that "K powder" is composed from typical 12 minerals such as Na2SO4, K2SO4, KCl, CaSO4, CaO, SiO2, 2CaO·SiO2, 2CaO·Al2O3·SiO2, 2CaO·Fe2O3, CaMg(CO3)2, Pb10(SiO4)3(SO4)3Cl2 and KCl·2PbCl2. The result set of equations was found to correspond with the measured values of free lime and residual solid contents determined by water washing treatment. Then, the estimating method could be demonstrated a good tool to identify the mineral composition of "K powder".
