Briquettes Compressive And Moisture Re-adsorption Feature Of Upgraded Lignite

The dissertation utilize three different types of coals for experimentalmeasurement which are V, D and Y. Quick dry moisture meter, infrared spectroscopy,contact angle meter, surface area analyzer and so forth are introduced to analyze thevariation of functional groups, wettability, pore structure and so on after differenttemperature refine Improvements. In addition, their re-adsorption differences arestudied to understand their mechanism. Each of the three coals’ no-adhesives coldpress molding was analyzed, the raw coal moisture content, briquetting pressure,dwell time, holding temperature and the coal ash, all these parameters’ effect on thetype coal impact strength are studied.Upgraded lignite doesn’t change the fundamental cage construction, but thenumber of oxygen-containing functional group decreases, the wettability also declines,the pore capacity and average pore diameter shows an upward trend,specific surface area is mainly contributed by micro-pores. Specifically, micro-poresspecific surface area account for40.87%,60.27%,50.02%of totalspecific surface area. In contrast, the pore capacity mainly comes from themiddle-sized pores, they makes up70.88%、59.67%、61.59%of all pore capacity.The briquetting of V and Y is relatively good, but D shows low ability ofbriquetting. The optimum moisture content for V is at10%,17%for Y and5%for D;under this specific condition, the shock resistance is23,5.5and13. Thebriquetting pressure and dwell time has minor effects on the forming ability of Dwhereas their effect on V and Y show an upward trend. When the pressure is20MPa,the impact strength reaches27and18. Ash content can enhance briquette coal’simpact strength. Orthogonal experiment show that the moisture content has the mostsignificant effect on the coal’s impact strength, briquetting pressure ranks the secondwhile ash content and dwell time has little effect on impact strength.The major parameters that affect lignite’s re-absorption is the refinementtemperature and the environment moisture. Fine-coal’s re-absorption ability increasesas the temperature and the environmental moisture increases. Usually, it can reachsaturation in about2days, the moisture content has no-determinacy compared withraw coal; Briquette needs a relative longer time period to regain re-absorption balance,the time length of re-absorption moisture for briquette is3times of fine coal whist theamount of re-absorption moisture is only about1/3of fine coal. In the briquette soaking experiment, briquette represents loose state in only80seconds, whichindicates the total waterproofness is not ideal.Brown coal refinement usually contains the drying and molding process, whichis a traditional method to transform brown coal into a low moisture and highcalorific value product. This method is of great importance for economicimprovement and environmental issues.