某进口赤-褐铁矿磨矿特性及其氧化球团制备行为

Grinding characteristics of an imported hematite-limonite and its oxidized pellet preparation behavior

利用价格相对低廉、资源丰富的赤-褐铁矿对于扩大球团原料来源、促进钢铁工业绿色转型具有重要的现实意义。针对某进口赤-褐铁矿(AM),研究了其湿式磨矿-沉降-过滤特性,同时对模拟链篦机-回转窑工艺条件下的球团焙烧行为、冶金性能和球团矿相特征进行了实验室实验和现场工业试验,揭示了配加AM对原料预处理和球团生产的影响规律。结果表明:AM属易磨矿石,由于含有褐铁矿,导致湿式磨矿后较难沉降、难过滤,实际生产中可通过与硬质铁矿搭配使用以改善沉降和过滤性能;当AM的磨矿细度(粒度小于0.074 mm质量分数)控制在70%~80%、混合精矿比表面积为1500 cm^(2)/g时,AM配比(质量分数)在0~40%范围内均可制备出抗压强度高于2500 N/个、RI>60%,RDI_(+3.15)>97%,RSI<20%的成品球团;但随着AM配比由0增加到40%,球团预热和焙烧温度需分别提高50℃。现场工业试验进一步验证了实验室结果,在链篦机-回转窑球团工艺热工制度基本稳定的条件下,AM配比宜控制在17%以内可获得良好的技术经济指标,继续提高AM配比则工序能耗将趋于增加。

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 graterotary 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(-0.074mm content)is controlled at 70 mass%-80 mass%,and the specific surface area of the mixed concentrates is 1500cm^(2)/g,qualified pellets(CCS≥2500N/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.