(S093)Alkali elution behavior of primary crystalline phases of CaO-SiO2-FeOx-MgO-Al2O3 system

摘要

When using steelmaking slag as a raw material of civil engineering works, the alkali elution will increase pH and cause environmental problem. Because steelmaking slag consists of various mineralogical phases, in a previous study, we synthesized and investigated the elution behaviors of several mineralogical phases that identified in the actual slag [1]. We find that in order to suppress the alkali elution, in addition to free CaO, the amount of 2CaO·SiO2- 3CaO·P2O5 (C2S-C3P) solid solution in steelmaking slag should also be decreased. Because the refining process has always been conducted under a C2S saturation condition, C2S-C3P is a stable phase even at high temperature, and thus the slag modification at hot stage appears to be a method to decrease the amount of C2S-C3P. After modification, various mineralogical phases which may not exist in current steelmaking slag will form due to the change in slag compositions. Therefore, in this study, several primary phases in CaO-SiO2-FeOx-MgO-Al2O3 system were selected basing on phase diagrams [2], and they were synthesized and their elution behaviors were studied.