Recovery of iron from red mud by pyrometallurgical method

Today, with the development of technology, the use of aluminum is rapidly becoming widespread in many different sectors. Aluminum is produced by Bayer Process from ore called bauxite. In this process, alumina is produced from bauxite ores, and then pure aluminum is obtained by electrolytic reduction from alumina. In this production chain; 1 ton of alumina is produced from 2 tonnes of bauxite ore. As a result of every 1 ton of alumina production, approximately 1 ton of red mud waste is produced. This red mud waste is pumped and stored in artificial ponds. In addition to the damages it may cause to the environment, this situation causes great land occupation and economic losses. Many researches have been carried out to evaluate the red mud, which has become one of the serious problems of the aluminum sector. Among these studies, researches aimed at recovering valuable metals such as Fe, Al and Ti from red mud are of great importance. In this study, recovery of iron, which is the most abundant metal in red mud, is studied. For this purpose, two mud samples were obtained from Eti Aluminum Co. in Turkey and Iran Alumina Co. in Iran. These samples contained 34% and 25.8% Fe2O3, respectively. Solid state reduction followed by wet magnetic separation was performed to recover the iron in the red muds. Reduction was carried out at temperatures ın between 1000 and 1200 ℃. Coal was used as reductant. The best coal ratio was determined as 20% more than theoretically required. Prior to wet magnetic separation, the reduced samples were milled in a ball mill for 24 hours. For comparison, non-milled samples were also subjected to wet magnetic separation. Although the milling process did not have a significant effect on the sample reduced at 1000 °C, it doubled the iron content of the concentrate obtaıned from the sample reduced at 1100 °C. Under the best experimental conditions, at the end of the magnetic separation process, 95% of the iron was recovered in a concentrate containing 61% metallic iron.