Grinding characteristics of an imported hematite-limonite and its oxidized pellet preparation behavior
The utilization of relatively inexpensive and abundant hematite-limonite is of great practical significance for expanding the raw material source of pellets and promoting the green transformation of the iron and steel industry.For an imported hematite-limonite(AM),its wet milling-settling-filtering characteristics were investigated,and at the same time,laboratory trials and on-site industrial experiments were conducted on the roasting behavior,metallurgical performance and microstructural characteristics of pellets under simulated grate-rotary kiln process conditions,revealing the influence of the addition of AM on the raw material pre-treatment and pellet production.The results show that AM is an easy-to-grind ore,which is difficult to be settled and filtered after wet milling due to the presence of limonite,and it can be used with hard iron ore to strengthen the settlement and filtration performance in the actual production;when the milling fineness of AM(-0.074 mm content)is controlled at 70 mass％-80 mass％,and the specific surface area of the mixed concentrates is 1 500 cm2/g,qualified pellets(CCS≥2 500 N/pellet,RI＞60％,RDI+3.15＞97％and RSI＜20％)can be prepared with AM ratios ranging from 0 to 40 mass％.However,with the increase of AM ratio from 0 to 40 mass％,the suitable preheating and roasting temperatures of pellets need to be increased by 50 ℃,respectively.The on-site industrial experiments further verified the laboratory results,under the condition that the thermal system of grate-rotary kiln pelletizing process is basically stable,the AM ratio should be controlled within 17 mass％to obtain good technical and economic indexes,and the energy consumption of the process will tend to increase if the AM ratio continues to be increased.
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维普
