Experimental Study On Beneficiation Technology Of Oolitic Hematite Ore From Middle East

With the development of steel industry, the demand for iron ore has been far from satisfying the rapid development of our country’s steel industry, the use of a large number of lean, fine and complicated mineral resources has been the growing concern by people. At the same time, The dependence of iron ore resources import also has been increasing year after year. This experimental study on beneficiation technology of an oolitic hematite ore from the Middle East, is an effort for the iron ore resources purchase by our country enterprises.This study of beneficiation technology of a oolitic hematite ore has adopted several kinds of experimental methods such as the magnetic separation, anionic reverse flotation, as well as the magnetization roasting method; optimized the experimental conditions of the magnetic separation, flotation and roasting processes; confirmed the final beneficiation process; provided experimental basis for the construction of this oolitic hematite ore dressing plant.According to the experimental study, we got the main conclusion as follows:(1) In the section of the study on technological mineralogy of the oolitic hematite, we used several measuring methods, such as X-ray diffraction (XRD) study, X-Ray Fluorescence (XRF) analysis, chemical analysis, and polarizing microscope, to determine the mineral phase, chemical composition, as well as minerals oolitic structure,and so on. Learning that this oolitic hematite contained28%of strongly magnetic maghematite,19%weakly magnetic hematite, a small amount of limonite and some gangue minerals like calcite, chamosite, and quartz, etc.The ore was a typical oolitic hematite ore, inside and among the oolitic particles, the fine hematite particles and gangue minerals were complexed symbiotic and stalemated each other so fine-grained that it was extremely hard to separate.(2) In the fraction of the magnetic separation technology research, firstly, we determined the process of stage grinding—one step rough separation and two step fine separation through low intensity magnetic separator. By different conditions experiments, we determined the grinding fineness, the magnetic field-intensity,the magnetic separation conditions for the second step separation and three step separation. The conditions of the first step rough separation processing were:grinding fineness was-0.074mm about87%, the field-intensity was0.12T; the second step fine separation grinding fineness was-0.025mm about89%, the field-intensity was0.08T; the third separation field-intensity was0.04T. After one step rough separation and two step fine separation operation, we achieved a qualified concentrate (magnetic product) with the Fe grade of61.11%and recovery of44.35%. These operations were carried out to recover maghematite in this oolitic hematite as possible as we can.At the same time, high-intensity or high-gradient magnetic separations were also performed on the roughing separation tailings, and then, two step was determined and the experimental condition was choosed as:the magnetic field-intensity of0.6T and0.8T. After rough separation and concentration separation, middlings with Fe grade of41.9%, and recovery of52.2%was produced. And then, in order to improve metal recovery, this study tried to explore the separation motheod of middling products. We have adopted two different methods, i.e., anionic reverse flotation and magnetized roasting-magnetic separation(3)In the floatation experiment part, superior performance of reverse anionic flotation was achieved to explore the optimum technological and operational conditions. The optimal conditions of anionic reverse flotation of hematite had been finally determined as follows:the collector dosage of1200g/t, NaOH1500g/t, the modified starch dosage of800g/t. and the activation agent calcium oxide dosage used in this work was controlled at300g/t. Under the optimal conditions, the iron concentrate had an iron grade of53.51%and an iron recovery rate of60.06%by one step reverse anionic flotation separation.under these optimal conditions, the desliming result is not ideal. Then, the middlings with the iron grade of41.94%were processed, and a13.84%flotation recovery,56.75%middling concentrate grade, In the stage grinding—magnetic separation—reverse anionic flotation a open flowsheet experiment, a comprehensive concentrate with iron grade of58.5%, recovery of57.19%; and a final tailing with iron grade of36.3%, and recovery of42.81%were finally obtained.(4)Experimental conditions of magnetization roasting were optimized to determine the optimum magnetic roasting—magnetic separation flowsheet; After groud to less than2.5mm, ore was uniformly mixed with anthracite powder as reductant, with the dosage of reductant of7%, and the optimized roast temperature of850℃, and time of60min in magnetic roasting process; The magnetic separation was performed by using a magnetic field intensity of0.12T and a griding fineness of87%less than0.074mm for the sintered product. Under these optimized processing conditions, the iron concentrate had an iron grade of61.79%and an iron recovery of77.79%.Under optimized processing conditions, middlings from the weak magnetic cleaners and high gradient scavengers were through the magnetic roasting-magnetic separation, which could produce iron grade of54.62%, and recovery of45.47%for rough concentrate after weak magnetic separation, besides the grade of tailings was reduced to18.26%. The flowsheet of magnetic roasting-magnetic separation for middlings was effective.At the same time, in the magnetizing roasting pilot-scale test for raw ore, magnetic drum magnetic separator produced better results than high gradient magnetic separator, but for middlings after magnetic roasting-magnetic, high gradient magnetic separator performed better, which gave beneficiation indexes consistent with magnetic tube separator, reflecting good reproducibility. These results can be used as the scientific basis for the industrial production.