Experimental Study On Magnetic Separation And Quality Improvement Of Guinea Lateritic High Iron Low-grade Bauxite

With the rapid development of aluminum industry,the growing demand for alumina and the lack of bauxite resources in China,they lead to a high dependence on foreign bauxite.Guinea is the largest source country of bauxite for China.The bauxite reserves of Guinea rank first in the world,and are concentrated with good quality and easy mining.At present,the Bayer method is widely used in China and abroad to extract alumina from bauxite,but this method requires relatively high iron content in bauxite raw materials.This is because too high iron impurity content in bauxite will increase energy consumption.Therefore,reducing the iron content of bauxite by beneficiation is an effective way to reduce the cost of alumina production.This paper takes the Guinea high-iron and low-grade bauxite as the research object.The properties of the ore are analyzed through XRD,chemical analysis,phase composition and particle size screening.And the separation effect of coarse and fine particles alumina is studied by magnetic separation.The“crushing and screening-coarse particle dry magnetic separation-fine particle pulsating high-gradient magnetic separation”is developed to achieve the purpose of improving the grade of aluminum and the ratio of aluminum to silicon,separating iron minerals.The aluminum of the bauxite is mainly gibbsite,and the main impurities are silicon dioxide,iron oxide and titanium dioxide.The grade of Al2O3 is 34.97%,the grade of iron is26.5%,the grade of silicon dioxide is 6.11%,and the ratio of aluminum to silicon is 5.72.It belongs to the low grade bauxite with high iron,low aluminum and medium aluminum to silicon ratio.The results show that aluminum concentrate with Al2O3 grade of 41.01%,recovery of76.02%was obtained by the single dry magnetic separation of coarse bauxite from 5.0?+2.0mm bauxite.Meanwhile the ratio of aluminum to silicon was 10.18 and the iron removal rate was 49.69%.-2.0 mm fine bauxite was separated by pulsating high gradient magnetic separation with one roughing and one concentration.An aluminum concentrate with Al2O3grade of 42.09%,recovery of 69.18%,the ratio of aluminum to silicon of 8.12,and iron removal rate of 53.62%was obtained.According to the analysis of the raw ore and the results of the magnetic separation,the magnetic separation process flow for removing iron and improving aluminum is determined as“crushing and screening-coarse particle dry magnetic separation-fine particle pulsating high-gradient magnetic separation”.The test results are as follows:the Al₂O₃ grade of the comprehensive aluminum concentrate is 40.76%,the recovery is 72.29%,the ratio of aluminum to silicon is 8.10 and the iron removal rate is 51.69%.The iron tailing Fe grade is35.25%,and the recovery is 51.69%.The effect of magnetic separation to improve aluminum grade is excellent.In this study,the process of"crushing ore screening-coarse grain dry magnetic separation-fine grain pulsating high gradient magnetic separation"was adopted,which was directly separated after crushing without grinding.It not only achieves the purpose of increasing the aluminum grade of bauxite and reducing the iron grade,but also reduces the output of fine particle bauxite.Magnetic separation has the advantages of low production cost,no pollution to the environment,easy product dehydration,and convenient long-distance shipping of products.It achieves the purpose of economically and effectively separating this kind of bauxite,and provides a scientific and reasonable technology for the comprehensive utilization laterite bauxite resources of Guinea.