TY - JOUR
T1 - Effect of MgO and CaO/SiO2 on the immobilization of chromium in synthetic slags
AU - Cabrera-Real, Hugo
AU - Romero-Serrano, Antonio
AU - Zeifert, Beatriz
AU - Hernandez-Ramirez, Aurelio
AU - Hallen-Lopez, Manuel
AU - Cruz-Ramirez, Alejandro
PY - 2012/10
Y1 - 2012/10
N2 - This work investigated the chemical and mineralogical properties of CaO-SiO2-Cr2O3-CaF2-MgO slags. Synthetic slags were prepared and the effect of the slag basicity (mass ratio CaO/SiO2) and MgO contents on the stability of the mineralogical species formed was analyzed. The morphology and composition of the slags were analyzed by X-ray powder diffraction (XRD) and scanning electron microscope-energy dispersive spectroscopy (SEM-EDS), whilst their chemical stability was evaluated by leaching with an aqueous acetic acid solution. It was found that in slags with CaO/SiO2 = 1, the main Cr-compound was MgCr2O4 spinel, which forms octahedron crystals. Small amounts of CaCr2O4 and CaCrO4 were also observed. It was found that with increasing the slag basicity from 1 to 2 the compounds MgCr2O4 and CaCr2O4 were formed together with the Cr(V)-containing compound complex Ca5(CrO4)3F which forms hexagonal crystals. The results showed that the highest Cr concentration levels in the leaching liquors corresponded to slags with CaO/SiO2 = 2, probably owing to the formation of CaCrO4 and Ca5(CrO4)3F, whilst the lowest chromium concentration levels corresponded to MgO-based slags owing to the stable binding of chromium in spinel with MgO. Additionally, potential-pH diagrams for the Ca-Cr-H2O and Mg-Cr-H2O systems at 25 °C were calculated.
AB - This work investigated the chemical and mineralogical properties of CaO-SiO2-Cr2O3-CaF2-MgO slags. Synthetic slags were prepared and the effect of the slag basicity (mass ratio CaO/SiO2) and MgO contents on the stability of the mineralogical species formed was analyzed. The morphology and composition of the slags were analyzed by X-ray powder diffraction (XRD) and scanning electron microscope-energy dispersive spectroscopy (SEM-EDS), whilst their chemical stability was evaluated by leaching with an aqueous acetic acid solution. It was found that in slags with CaO/SiO2 = 1, the main Cr-compound was MgCr2O4 spinel, which forms octahedron crystals. Small amounts of CaCr2O4 and CaCrO4 were also observed. It was found that with increasing the slag basicity from 1 to 2 the compounds MgCr2O4 and CaCr2O4 were formed together with the Cr(V)-containing compound complex Ca5(CrO4)3F which forms hexagonal crystals. The results showed that the highest Cr concentration levels in the leaching liquors corresponded to slags with CaO/SiO2 = 2, probably owing to the formation of CaCrO4 and Ca5(CrO4)3F, whilst the lowest chromium concentration levels corresponded to MgO-based slags owing to the stable binding of chromium in spinel with MgO. Additionally, potential-pH diagrams for the Ca-Cr-H2O and Mg-Cr-H2O systems at 25 °C were calculated.
KW - Chromium oxide
KW - Magnesium oxide
KW - Slag
KW - Waste management
UR - http://www.scopus.com/inward/record.url?scp=84867858570&partnerID=8YFLogxK
U2 - 10.1007/s10163-012-0072-y
DO - 10.1007/s10163-012-0072-y
M3 - Artículo
SN - 1438-4957
VL - 14
SP - 317
EP - 324
JO - Journal of Material Cycles and Waste Management
JF - Journal of Material Cycles and Waste Management
IS - 4
ER -