The Effect Of Heat Treatment-grinding Aids On Oolitic Hematite Liberation

As one of the refractory ores,oolitic hematite is widely distributed in the world and has large reserves.However,owing to its complex structure,fine particle size and many kinds of associated gangue minerals,its large-scale development and utilization have not yet been realized.In this paper,the effect of heat treatment and grinding aids on the particle size and hematite liberation of grinding products is studied based on the process mineralogy of high phosphorus oolitic hematite in Western Hubei.And the mechanism of these is analyzed.The conclusions are as follows.Under the conditions of grinding time 30 min,sodium oleate dosage 0.3% and grinding concentration 70%,the percentage of-0.074 mm increased from 68.20% to 74.20%,the liberation of hematite is increased from 63.98% to 69.43%.And when sodium lignosulfonate dosage 0.05% and grinding concentration 65%,the percentage of-0.074 mm is increased from 68.90% to 73.20%,the iberation of hematite is increased from 64.70% to 66.27%.And when sodium dodecyl sulfonate dosage 0.05% and the grinding concentration 60%,the percentage of-0.074 mm is increased from 69.50% to 72.60%,the liberation of hematite is increased from 65.60% to 67.77%.Among the above grinding aids,sodium oleate has relatively good grinding efficiency.Adding grinding aids in the grinding process can reduce the pulp viscosity or ore surface hardness to improve grinding and hematite liberation.The best grinding efficiency can be obtained under the conditions of ore particle size 7-10 mm,heating treatment temperature 500?,time 30 min and water quenching.Compared to the results of no heating treatment,the ore compressive strength decrease 56.65% and the percentage of-0.074 mm productions increases 15.9%.After heating treatment,there are micro-cracks in the ore,the strength of the ore decreases,and the grindability improves.Because of these micro-cracks,different components are easier to separate in the grinding process.Under the optimum conditions of heating treatment and grinding aids,compared with the results of direct grinding process,the percentage of-0.074 mm productions in grinding products with sodium oleate,sodium lignosulfonate and sodium dodecyl sulfonate increased from 68.20%,68.90%,69.50% to 76.90%,76.10% and 75.30%,respectively,and the liberation of hematite is increased from 63.98%,64.70% and 65.60% to 80.60%,75.30% and 77.40% respectively.The increase of grinding efficiency was obvious and the hematite liberation improved.After heat treatment,there are micro-cracks generating in the ore,so the strength of the ore decreases and the grindability improves.And there is synergistic effect between heat treatment and grinding aids.In the process of liquid nitrogen cold treatment,the best grinding efficiency can be obtained under cold treatment 15 minutes and 2 times.Compared with the results of direct grinding process,the percentage of-0.074 mm productions is increased from 70.10% to 73.28%.Under the optimum conditions of cold treatment and grinding aids,compared with untreated grinding products,the percentage of-0.074 mm productions of adding sodium oleate,sodium lignosulfonate and sodium dodecyl sulfonate are increased from 68.20%,68.90%,69.50% to 75.30%,74.80%,74.50%,and the hematite's liberation are increased from 63.98%,64.70%,65.60% to 77.60%,73.40% and 74.50%,respectively.This indicated that cold treatment-grinding aid process can process can obviously improve grinding efficiency,increase the percentage of-0.074 mm production and the liberation of hematite,and there is a synergistic effect between cold treatment and grinding aids.