This work investigates the stabilizing impact of MnO on the leaching behavior of hazardous Cr-containing CaO-SiO2-Al2O3-Cr2O3-MnO stainless steel slags after equilibrating at various elevated temperatures and evaluates the potential immobilization of Cr into a MnCr2O4 spinel phase from the existing Cr2O3 phase. The MnCr2O4 spinel phase was found to be an excellent Cr-stabilizer in stainless steel slags, where the leaching tendency of potentially hazardous Cr-related ions decreased with higher MnO content and lower equilibration temperatures within the range of 0 to 15 mass pct. and 1500 to 1300°C, respectively. Thermodynamic calculations by conducting the phase stability diagram also showed that the MnCr2O4 spinel phase was relatively stable and the Ca3Si2O7 (Ca3-xMnxSi2O7) phase was relatively unstable compared with other crystal phases in acid extractant with pH value of 3.2. Combined with the scanning electron microscopy and X-ray powder diffraction results along with the thermodynamic calculations, the leached Cr-related ions was predominantly originating from the unstable amorphous glass phase.
Bibliographical noteFunding Information:
This work was supported by the third stage of the Brain Korea 21 Plus Project in 2020 and the National Research Foundation of Korea (NRF) grant funded by the?Korea government (MSIP)?(No.?2018R1A2B2006609).
All Science Journal Classification (ASJC) codes
- Ceramics and Composites
- Materials Chemistry