Study On Enhancing Technology And Mechanism Of Oxidized Pellet Prepared From Pyrite Cinder By Moisture Grinding

Pyrite cinder is one of the most important industrial waste residues. Which causes pollution of land and water, harms the growth of animals and plants. So pyrite cinder can do great harm to environment, also make the rich iron resources waster. However, the iron ore resources are insufficient and mainly depend on imported in our country, so pyrite cinder is valuble. With development of production technology and equipment, the iron grade of pyrite cinder has been improved and pyrite cinder directly to produce pellet becomes possible. In this paper, the characteristics and reasons of the balling and roasting have been discussed, and effect of moisture grinding on pellets have been studied.Pelletizing process of pyrite cinder shows that the strength of green balls is very bad and the moisture of green balls is high without moisture grinding. Moisture grinding is an effective means to improve the strength of green balls, lower the dosage of bentonite and moisture of green balls. Under the condition of moisture grinding 4 min and adding 1.0% of Shanxi sodium bentonite, the drop strength, compressive strength, thermal shock temperature and moisture of Shanxi pyrite cinder green balls are respectively 3.7 time/0.5m, 15.61N/P, 575℃and 13.40%; the green ball of Zhengzhou pyrite cinder changes into 3.9 time/0.5m, 15.60N/P, 600℃and 13.18%. Under the condition of moisture grinding 6 min and adding 1.6% of Shanxi sodium bentonite, the drop strength, compressive strength, thermal shock temperature and moisture of Jiaozuo pyrite cinder green balls are 3.0 time/0.5m, 10.74N/P, 584℃and 13.06%, respectively.Roasting performance of pyrite cinder suggests that moisture grinding also helps to improve the roasting performance of pyrite cinders pellets. Under the condition of moisture grinding 4 min, preheating 950℃for 10 min and roasting 1150℃for 10 min, the pellets' compressive strength of Shanxi pyrite cinder is 3230N/P; while the Zhengzhou's is 2869N/P. Under the condition of moisture grinding 6 min, preheating 975℃for 10 min and roasting 1150℃for 10 min, the pellets' compressive strength of Jiaozuo is 3046N/P. Pyrite cinders pellets can be obtain good strength with roasting temperature from 1150℃to 1200℃, which lower 100℃than the magnetite pellet, which has important significance for energy saving.Study on moisture grinding to improve the quality of pellet indicates: (1) moisture grinding can improve the quality of pyrite cinders' green balls. The reason is not only that moisture grinding can improve size distribution, granule morphology and specific surface area, but also moisture grinding destroys pyrite cinders' structure which looks like honeycomb, make the green ball more compact and lower the porosity of green balls. So the strength is increased significantly, and moisture is significantly reduced. (2) The reasons for moisture grinding improve the roasting performance of pyrite cinders' pellets are that: firstly, pyrite cinder is artificial ore, whose activity is higher than natural iron mine; secondly, moisture grinding improve the surface energy of pyrite cinder and increase contact points between particles, which is the advantages of diffusion. (3) The effect of desulfuration is very well. When the desulfuration occurs, it releases a lot of heat which promotes oxidation and consolidation of pyrite cinders' pellets.Pyrite cinders with moisture grinding, the quality of green balls, the physical properties and chemical composition, and metallurgical performance of pellets all can meet the production requirement. This technology will help to solve the pollution of pyrite cinder and expend raw material sources for steel industry, and provide the theoretical and technological base for multipurpose utilization of pyrite cinders.