The use of chromium compounds such as sodium chromate, sodium dichromate and green chromium oxide in textile, tile making, ceramic and pigment industries is very widespread in Iran. In order to prevent the import of these essential compounds at a very high cost and also to prevent the sale of raw chromite in Iran, research to promote the production of these chemicals from domestic chromite ore has become an important issue. In this research, the aim is to make chromium (III) oxide from domesti chromite concentrate with a grade of 32% by the alkaline roasting method of chromite with sodium carbonate and also to optimize the alkaline roasting step. Alkaline roasting of chromite concentrate was done in different ratios of sodium carbonate, at different temperatures and times, and in air atmosphere. The obtained results showed that the optimal conditions for alkaline roasting occurred in the molar ratio of sodium carbonate to chromium oxide 2.5, the roasting temperature was 1000 degrees Celsius and the duration was 2 hours. By dissolving the product of alkaline roasting in water, a significant part of impurities and compounds insoluble in water, Such as unreacted chromite and iron and magnesium compounds were precipitated. Reducing the pH of the solution was used to separate water-soluble impurities. As a result of pH decrease, part of sodium chromate was converted into sodium dichromate. As the pH decreased, more sodium chromate was converted to sodium dichromate, which caused the color of the solution to change from yellow to dark orange. Finally, sodium chromate and sodium dichromate dissolved in water were used to produce green chromium(III) oxide. Chromium oxide and hydroxide were made from the solution containing sodium chromate and sodium dichromate by three methods: evaporative crystallization and mixing with sulfur, adding sodium sulfide to the boiling solution, and adding an emulsion containing sulfur and sodium hydroxide to the boiling solution. In the method of adding sulfur, a solution with pH = 5 was used because it has a high amount of sodium dichromate, and in the method of sodium sulfide, a solution with pH = 9 was used because it has a high amount of sodium chromate. Sulfur emulsion method could be used in all pH. The product produced in the method of mixing sodium dichromate with sulfur was directly chromium oxide, while the product produced in the other two methods is chromium hydroxide, which can be calcined to produce green chromium (III) oxide. The sulfur emulsion method was eva‎luated more due to having more advantages than the other two methods. The purity of chromium oxide made by sulfur emulsion method was 97%.

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محمود مراتيان اصفهاني , رحمت اله عمادي