| The combined flowsheet of stage grinding, stage magnetic separation, regrinding the iron tailing, high intensity magnetic separation and flotation was mainly adopted to recycle titanomagnetite and ilmenite successively with vanadium-titanium magnetite in Panxi. Recovery of TiO2 in titanium concentrate was relatively low because of the over-grinding of ilmenite caused by the complicated process. High pressure grinding roller is efficient crushing equipment, which is based on laminated crushing. Products crushed by HPGR were fine of grain size, uniformly distributed and generated large number of micro-cracks internal the ore particles. Application research of HPGR on ultra-finely crushing and subsequent separation of vanadium-titanium magnetite in Panxi has important practical significance.The technological mineralogy characteristics of vanadium-titanium magnetite in Panxi were firstly studied in this paper. The results showed that the main metal minerals were titanomagnetite, ilmenite, trace titanium hematite (limonite) and pyrrhotite etc and the main gangue minerals were pyroxene, feldspar, chlorite and minor carbonate, olivine, epidote etc.. The Fe and Ti exist in the form of titanomagnetite and ilmenite. The primary crystal grain size of the main purpose minerals are thicker, about 50% of titanomagnetite crystal particle are 0.178mm of the size and about 50% of the ilmenite crystalline particle are 0.15mm of the size.Ultra-finely crushing tests including size characteristics of the product influenced by the pressure and speed of the roller, the moisture content and feed size of the vanadium-titanium magnetite in Panxi were conducted using HPGR in the paper. The productivity of -5mm,-3.2mm and -0.074mm of the centre product is respectively 96.69%,91.05% and 15.29% under the condition that the pressure of the roller is 5.6N/mm2, the speed of the roller is 0.195m/s and the moisture content of the ore is no more than 5%. The P80 of the centre product is reduced to 1.55mm and the ratio of reduction is up to 10. Tests of influence of different processes of edge-circuit and classification closed-circuit on the size characteristics of the product were also conducted in the paper. The results showed that the P80 of the centre product was reduced to 1.45mm with the increasing of the edge products circulating mass and the fine fraction content of crushing products from classification closed-circuit increased obviously and the Pgo of the product was reduced to 1.05mm and which can be separated by magnetic separator directly.Separation of vanadium-titanium magnetite ultra-finely crushed by HPGR was carried out with process of parallelly separating Fe and Ti. Titanomagnetite and ilmenite of the ore were parallelly separated by the wet coarse magnetic separator first and then further sorted pertinently. Iron concentrate with Fe grade 55.05% and recovery 70.64% can be obtained by grinding to -0.18mm accounted for 95% (which is equivalent to -0.074mm accounted for 45%) and two stages of low intensity magnetic separation from the concentrate of the wet coarse magnetic separator. And titanium concentrate with TiO2 grade 48.08% and operation recovery 40.15% can be obtained by grinding to -0.074mm accounted for 80%, separating iron by low intensity magnetic separator, high intensity magnetic separation for discarding tailings, desulfurization, floating ilmenite from the tailing of the wet coarse magnetic separator. Stage grinding, stage magnetic separation, regrinding the iron tailing, high intensity magnetic separation and flotation were adopted to sort the vanadium-titanium magnetite crushed by Jaw Crusher. Iron concentrate with Fe grade 54.95% and recovery 71.07% and titanium concentrate with TiO2 grade 48.15% and operation recovery 39.06% can be obtained by two stages grinding of the ore to -0.074mm accounted for 65% and regrinding of the tailing of the ore to -0.074mm accounted for 80%. The Fe recovery of iron concentrate was increased with 0.43% and the TiO2 recovery of titanium concentrate was decreased with 1.09%. The result of the close circuit test showed that the grade of the iron concentrate and titanium concentrate reached the requirements of the plant, and the TiO2 recovery of titanium concentrate of the first flowsheet was increased with 1.03%.Characteristics of size and grinding of the vanadium-titanium magnetite ultra-finely crushed by HPGR were studied in the paper. The results showed that the change of the particle size of ore was closely related with the pressure on roller surface and the reduction ratio increased with the increasing of the pressure. The particle size decreases but uniformity reduces with increasing of the edge products circulating mass. And compared with that by Jaw Crusher, the fine fraction content of crushing products from classification closed-circuit by HPGR increases obviously and particle size distribution is more uniform.The Bond work index of ball mill (objective particle size is 0.074 mm) of the vanadium-titanium magnetite ultra-finely crushed by HPGR is 24.77 kW-h/t, and which is lower by 14.05% than that by Jaw Crusher. The relative grindability of product crushed by HPGR is 87.08% to that by Jaw Crusher. Intra-crystalline cracks and cleavage cracks are generated in vanadium-titanium magnetite crushed by HPGR. The BET specific surface area of respective fractions of the products crushed by HPGR increased significantly compared with corresponding grain size of that of Jaw Crusher. The micro-cracks and surface roughness of the products crushed by HPGR is greater than that of Jaw Crusher when the particle size is less than 0.18mm. In the case of similar grinding fineness, the mineral liberation degree of vanadium titanium magnetite ultra-finely crushed by HPGR was averagely 0.53% higher than that by Jaw Crusher and the influence of the ultra-finely crushing by HPGR on mineral liberation degree gradually weakened with the increasing of the grinding fineness.The separation of titanomagnetite and ilmenite could be realized to a certam extent by the wet coarse magnetic separator due to the reducing of the particle size of vanadium-titanium magnetite ultra-finely crushed by HPGR, which results in the parallelly separation of Fe and Ti can be achieved. Micro-cracks caused by the ultra-finely crushing by HPGR made the ore easy to grind and qualified iron concentrate can be obtained by only one stage grinding and low intensity magnetic separation. The TiO2 recovery of titanium concentrate can be improved by reducing the segments of grinding of part of ilmenite and the generating productivity of the ilmenite of -0.019mm in the process of parallelly separation of Fe and Ti.Process of ultra-finely crushing by HPGR and parallelly separation of Fe and Ti in this paper provides a new approach for the efficient utilization of the vanadium-titanium magnetite in Panxi. It has important guiding significance on the application of HPGR in the separation of vanadium-titanium magnetite. |
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