Separation of vanadium and chromium from vanadium-chromium slag by high-temperature heating

A method to separate vanadium (V) and chromium (Cr) from vanadium-chromium (V-Cr) slag was developed to treat the hazardous substances effectively. This approach was achieved by heating V-Cr slag with Na 2 CO 3 in air within a temperature range of 30 °C to 1400 °C. Through TG-DSC, XRD, SEM-EDS and XPS tests, the results showed that Na 2 CO 3 reacted with V compounds at lower temperatures, producing NaVO 2 and Na 3 VO 4 . At the high-temperature stage, Na 2 CO 3 reacted with Cr compounds, resulting in Na 2 CrO 4 and Cr 2 O 3 formation on the slag surface. As the temperature exceeded 1200 °C, volatiles (Na 2 CrO 4 , NaCrO 2 , and other Cr compounds) were generated from the residuals and collected by condensation to separate V and Cr. This method provides a novel strategy for eco-friendly resource utilization of V-Cr slag, which is highly efficient, minimizes hazardous wastes, and can be further promoted in the industry.