Study On Techniques Of Low Rank Coal CWS Preparation By Using Of Freezing Treatment

Coal water slurry is a suitable fuel for oil replacing, energy saving, environmental protection in China’s national conditions,it ensures long-term stable development of China’s energy strategy and practical choice. In industrial application, how to make the low rank coal to produce high grade coal water slurry, how to improve low rank coal grinding, improve the rod milling efficiency is the focus and difficulty in the present study of coal water slurry, it has important research significance and application prospect.In this paper, the effect of freezing on the performance of pulverized coal was studied firstly, and it was found that with increasing of freezing time, HGI of the coal can be increased. Treatment effect of freezing-thawing was better than that of the freezing process. Effect of freezing temperature on the grinding performance shows that the lower freezing temperature and the longer freezing time, the better of coal grinding effect.Secondly, this paper proposes the use of natural freezing method to improve the pulping characteristics of low rank coal, and further explores its mechanism. For the high water content, low HGI Hongshiwan coal, Bayangol coal, Yangyikuang coal, after freezing the coal grinding efficiency significantly increased. By natural freezing 200 mesh passing rate of Bayangol coal water slurry increased about 4.92%, Yangyikuang coal increased about 4.06%, Hongshiwan coal increased about 7.06%.By using of industrial CT, DSC, FT-IR analysis, impact strength, hardness, abrasion test, microscopic observation and other methods to test and analyze the coal, the migration mechanism of moisture and mechanism of coal petrology freezing brittleness are summarized. The study found that moisture in coal of freezing process, will change from crystal water, pore water to structural water. Coal petrology in icy or freezing-thawing process cause self maceral stripping or swelling, lead to strength decreasing of low rank coal. It is found that freezing can decrease the hardness of coal by using of coal hardness test, but it is not proportional to freezing time. When the freezing time is more than 7 days,the hardness of coal will increase.The impact strength of the test found that, compared to the coal untreated, the brittleness of freezing process coal increased, easily broken, with the increasing of freezing time, the greater of the brittleness.Finally, through cold model experiment, coal water slurry industral production process and stress of coal in rod mill crushing process be simulated and animated by using of Flash software and ANSYS software. And compared different steel bar gradation coal crushing effect. Experimental results show that coal broken degree of φ75, φ65,φ55 steel bar grading is better than φ70,φ>65, φ60 steel bar grading.