Comprehensive Utilization Of Red Mud

It is the need of sustainable development to rational use of natural resources of aluminum and secondary resources. As the lower of the bauxite grade, the ore has been tied up to import, and emissions of the red mud increase every year, the red mud takes up a lot of land, damages to the ecological environment. So it is necessary to multi utilization of the red mud.It has shown that to extract the sodium in the red mud by using carbon dioxide with the Bayer carbonation dealing with the red mud, sodium can be extracted50.1%. In the same carbon sub-conditions, the extraction rate of sodium is17.3%in the red mud which is produced by hybrid method. The extraction rate of sodium increases with increasing temperature, pressure, and time.It has solved the problem of leaching of sodium and increase economic efficiency with citric acid to leach red mud in normal temperature and normal pressure. Concentrated sulfuric acid roasting of leaching residue can make valuable elements of iron and aluminum recycled, it provide a new way for the comprehensive utilization of the red mud.The research of using Citric acid to leach the red mud showed that:1. In the experiments with citric acid to leach the red mud, the leaching rate of iron, aluminum, calcium, silicon increase with the temperature rising, the time extension and the amount of citric acid addition. At room temperature the leaching rate of sodium has more than85%, and the others are the lowest.2. The sodium can be extracted with citric acid in the red mud. When the added amount of citric acid is1.6times than the required to leach the sodium, and at the conditions of the leaching temperature is20℃, the extraction time is30min, the leaching rate of sodium has reached88.3%in the Bayer red mud; In the Hybrid red mud the leaching rate of sodium can reach85.42%, the leaching rate of iron is2.45%, the leaching rate of aluminum is16.3%, the leaching rate of calcium is12.5%.3. It has shown that the recovery rate of aluminum increases with the roasting time extension and the amount of concentrated sulfuric acid added in the roasting of single factor experiments increasing. The best roasting process conditions is determined by the orthogonal experiment, the roasting conditions is410℃,3h, the adding amount of concentrated sulfuric acid atl:1.8, it can leach almost all the iron, and the leaching rate of aluminum is89.8%.4. The recovery rate of iron and aluminum is different because of the different ending pH in making vanadium, they increase with the pH increases, and when the pH has more than4, the recovery rate of iron stabilizes at around99.8%, the recovery rate of aluminum stabilities at around99%.5. It has shown that in the experiments of leaching vanadium slag with alkali the leaching rate of aluminum increases with the time extension, the temperature increasing, the added amount of alkali increasing. At the room temperature, stirring30min, adding5times of the KOH than the required which can making a complete reaction with the aluminum in the vanadium, the recovery rate of aluminum is85.46%.6. The iron products contain hematite and a small amount of titanium dioxide and potassium hydroxide. It has shown that with the scanning electron microscopy the size of the particles is very small, spherical; they are very easily to reunion large irregular shape, rough surface of particles. Aluminum in the aluminum products in the form of alumina, the particle size is very small, spherical. They are very easy to reunion large irregular shape, rough surface of particles.