The Al₂O₃-CaO-MgO-Cr₂O₃ system has immense potential for refractory castables applications. However, Cr(III) can potentially be oxidized to carcinogenic Cr(VI) during the usage, which can cause subsequent problems with disposal. Equilibrium experiments on the Al₂O₃-CaO-MgO-4wt%Cr₂O₃ system were performed at 1500 °C in air. The effect of MgO addition (0 and 20 wt%) on the formation and leachability of hexavalent chromium was investigated using XPS, XRD, SEM-EDS, the TRGS 613 standard Cr(VI) leaching test and multiple leaching tests. A Cr(VI)-containing phase Ca₄Al₆CrO₁₆ predominantly formed in the samples with 0 and 5 wt% MgO, while the Cr(III)-containing Mg(Al, Cr)₂O₄ spinel phase formed in the samples with 10 and 20 wt% MgO. Addition of MgO suppressed the formation of Cr(VI) while favored the formation of spinel phase. Concentrations of Cr(VI) in the leachates from TRGS 613 tests exceeded the European limit of 0.0002 wt% in all samples, although decreased significantly with 20 wt% MgO addition.

Al ₂ O ₃ -CaO-MgO-Cr ₂ O ₃系统在耐火浇注料应用中具有巨大的潜力。但是，在使用过程中，六价铬可能会被氧化成致癌的六价铬，这可能导致后续的处置问题。在空气中于1500°C下对Al ₂ O ₃ -CaO-MgO-4wt％Cr ₂ O ₃体系进行平衡实验。使用XPS，XRD，SEM-EDS，TRGS 613标准Cr（VI）浸出试验和多次浸出试验研究了添加MgO（0和20 wt％）对六价铬形成和浸出率的影响。含Cr（VI）的相Ca ₄ Al ₆ CrO₁₆在样品中主要以0和5 wt％的MgO形成，而含Cr（III）的Mg（Al，Cr）₂ O ₄尖晶石相在样品中以10和20 wt％的MgO形成。MgO的添加抑制了Cr（VI）的形成，同时有利于尖晶石相的形成。来自TRGS 613测试的渗滤液中的Cr（VI）浓度在所有样品中均超过了欧洲极限0.0002 wt％，尽管添加20 wt％MgO会显着降低。