Study On Recovering Iron From Red Mud In Magnetic Seeding With Hydrophobic Agglomerating And It's Mechanisms

The red mud is the tailing produced during the process when separating alumina from bauxite. The red mud not only seriously polluted the environment, but also led to a waste of resources because the comprehensive utilization of red mud has not been resolved for a long time.Pingguo Aluminum Company is one of the largest production bases of alumina in our country. The red mud produced in it contains a certain amount of iron, the content of iron is about 24%, which will be a new resource of iron. Iron mainly presents in the form of fine hematite in the red mud. So it is important that special technological methods must be used in order to recover hematite effectively from the red mud.On the basis of summary and analyse of many interrelated documents both at home and abroad, systematical experiments had been carried out to recover iron from Pingguo red mud. The experimental method is called the magnetic separation of magnetic seeding with selective hydrophobic flocculation.Through magnetic separation experiments of magnetic seeding with selective hydrophobic flocculation, these factors had been examined such as magnetic intensity, slurry concentration, stirring time, dosages of disperser and flocculant etc. to study the influence on the iron separation efficiency of Pingguo red mud.Various measurement techniques had been used, such as Zeta potential measurement, particle size analysis, electronic micrography, infrared spectroscopy and the calculation of interaction energy among mineral particles to study the reaction mechanisms of Pingguo red mud.Results of various separation tests indicate that magnetic separation of magnetic seeding with selective hydrophobic flocculation is the most effective method to recover fine hematite from Pingguo red mud. Under colligating optimum experimental conditions by used this method the iron's grade is up to 50.62% and it's recovery reaches 45.97%. Up to present it is the best result by using mineral processing method to recover iron from Pingguo red mud.The results of zeta potential measurements showed that potential of hematite and magnetic seedings obviously moved to negative pole after treated with sodium hexametaphosphate and other gangue minerals' surface potential did not change more. It was indicated that sodium hexametaphosphate could selectively disperse Pingguo red mud.The results of particle size analysis indicated that coarse grain size range of Pingguo red mud treated with the mixture of oleic acid and kerosene was broader than untreated one, and the former average particle size is much bigger than the latter. It was illuminated that after treated with the mixture of oleic acid and kerosene, fine particles of Pingguo red mud could be flocculated together effectively.The electronographs showed that after treated with the mixture of kerosene and oleic acid, hematite could be flocculated with each other very well. After adding magnetic seeding, it could be found in electronographs that magnetic seeding could adhere to the hematite floccules selectively to result in the increase of hematite magnetic susceptibility.The results of infrared spectroscopy showed that compared with untreated mineral and reagents, it appeared many new characteristic absorption peaks in infrared spectrogram of hematite and Pingguo red mud treated with the mixture of oleic acid and kerosene. Some peaks also moved a bit. It was indicated that both physical adsorption and chemical adsorption had taken place in the surfaces of hematite and Pingguo red mud reacted with the mixture.The calculation results of interaction energy among particles indicated that fine hematite and gangue minerals could be dispersed when adding sodium hexametaphosphate to the pulp. After treated with the mixture of oleic acid and kerosene, the increasing of hydrophobic interaction attractive energy was the main reaction mechanism when hydrophobic flocculation occurred among mineral particles.