Optimizing Technological Parameters for Chromium Extraction from Chromite Ore Beneficiation Tailings

This study focuses on optimizing the alkali roasting conditions for chromite beneficiation tailings with the goal of enhancing chromium oxide (Cr2O3) extraction. Within the experimental framework, the variables included roasting temperature, the amount of added Na2CO3, and reaction time. The results revealed that temperature is the most critical factor directly affecting the extraction efficiency. Increasing the amount of Na2CO3 contributed to an increase in Cr2O3 recovery, although excessive addition may not be economically justified. The optimal conditions—1000 °C, 120%–130% Na2CO3 (relative to tailings mass), and 120 min—enabled a Cr2O3 extraction rate of up to 98.6% through aqueous leaching. The phase transformation analysis confirmed the breakdown of the spinel structure and formation of water-soluble sodium chromate. Microanalysis observations and measurements validated the progressive destruction of chromite grains and sodium enrichment in the reaction zones. The remaining leaching residue consisted of inert Na2Mg2Si2O7 and MgO, suitable for further metal recovery. The proposed approach enables efficient detoxification of hazardous tailings and serves as a basis for integrated utilization of Cr-bearing industrial waste.