Steam Rotary Drying Technology Application Research In Coal Slime Drying

Coal Slime is a by-product of coal washing.It is a low-heat coal and has potential utilization value.However,it is difficult to be directly used in the process industry.The form of coal slime is unstable,which has bad influence to the environment.Accordingly,the harmless treatment and reuse of coal slime has significant importance.Drying is an effective means to improve the quality of coal slime and expand its use.Traditional flue-gas direct drying technology has low thermal efficiency.The dust is difficult to be removed.Overall,this technology is not good for energy conservation and environmental protection.In this paper,the split-type steam rotary drying technology is applied in the coal slime drying.The key parameters such as static drying characteristics,drying temperature and filling rate of slime were experimentally studied.Besides,the industrial production equipment was established for the purpose of verification.In the study of static drying of coal slime,the result of the water loss rate increased with the increase of the temperature through TGA experiments.When the temperature of coal slime is between 65 and 70,the desiccation rate of slime was accelerated with the increase of drying temperature by constant temperature drying test.In addition,the caloric value of coal slime before and after drying was measured.In the dynamic drying study of coal slime,the drying speed was much higher than static condition by intermittent small experiment,and the drying speed was significantly improved with the drying temperature.Filling rate experiments show that the filling rate is too large or too small will reduce the equipment Dehydration strength,in the small experimental device,the best filling rate is about25%,the maximum drying strength of 6.96 kg-water/(m~2.h).Through the continuous pilot experiment,the paper studied the sticky wall of coal slime under different water content.The results show that when the moisture content of the slime less than 23.05%,the viscosity of the slime is slight.The pilot experiment also determined that the suitable steam pressure was 0.6 MPa,coal slime drying time is 20 minute,the drying strength is up to 7.52 kg-water/(m~2.h),the steam consumption is 0.231t/t-slime.According to the results of the experimental,the rotary steam drying technology was optimized,and the industrial production plant with the capacity is50,000 tons per year was established in Zibo Group Port Village Coal Mine.The results show that the technology has high quality,low energy consumption and no adverse effect on the environment.It has good applicability to slime drying and has a payback period of only 1.67 years,which has good economic and environmental benefits.