Experimental Research On Cement Clinker Calcination With Coal Stone As Argillaceous Material

Coal is the main energy consumption in China. In recent years, the coal consumption increased dramatically, especially the consumption of coal for power generation. But large amount of low quality coal resources, such as coal stone, are not fully used. A few coal stone are used for combustion, but it generate huge amount of cinder, ashes and also the sulphur dioxide emission which bring heavy load to the society and the environment. In order to solve the problems, the novel method for utilizing the coal stone resources should be developed to meet with our nation's goal of Recycling Economy.Based on the geographic characteristics of coal stone distribution in China, 6 typical coal stone from Zhejiang Province, Hunan Province, Guangxi Zhuang Autonomous Region and Gansu Province were sampled for the tests. With chemical analysis and XRD analysis, it can be found that the coal stone has the similar mineral constitution and chemical component with the conventional argillaceous materials. So it can be assumed that the coal stone can be used in cement industry to substitute the conventional argillaceous materials. On the other hand, stone coal with a certain heating value can be combusted and support heat during the calcination process to save coal consumption in the cement industry.In this experiments, Three modulus KH=1.000, SM=3.1, IM=1.3 were set in advance, and the Degression Making-up Method was adopted to calculate how many raw material would be used in raw meal. Then according to the calculation results and the raw material chemical analysis, the raw meals were mixed and milled in ball grinder, then calcined in electrical furnace. During the grinding process, the grindability of the raw meal was studied.In order to find proper calcination system, the experiments adopted 1250°C, 1300°C, 1350°C, 1400°C and 1450°C as its calcination temperature to test the feasibility of the utilization of coal stone. Based on the labscale experimental results, when the temperature reached 1350°C, it is found that large quantity of liquid phase appeared and the color of the clinker became darker. At last the lab clinkers had the same appearance with the industrial clinkers. The free-lime decreased dramatically below 1% when the calination temperature reached 1350°C. By XRD analysis, it was obviously that the mineral constituent in the lab clinkers contained the same mineral constitution to the industry clinker, and the mineral variations are minor with the temperature increasing after the calcinations temperature reached 1350°C.With the XRD analysis on the clinker, it was found that the clinkers we got in lab had minor variation with the clinkers that we got in cement factory. With the quantity analysis by XRD, the amount of C₂S,C₃S,C₃A,C₄AF had already had the proper ratio in our clinkers, and can satisfy the cement industry standard.At last compression strength tests were taken to determine whether the clinker can meet the construction requirement. With the tests results, it was found that the compression strength had already had the same or exceeded the standard currently used in cement industry. And considering the C₂S quantity in our clinkers, it's sure that the late strength would be much stronger than that of the clinker produced in current cement factory. So it is possible that this method that we adopted can help the cement industry make certain progress in future.Generally speaking, utilizing coal stone to substitute the conventional argillaceous material is feasible. And because of the heating value in coal stone, energy consumption can be reduced with the utilization of coal stone. For the utilization of the coal stone, clay usage decreased obviously in cement raw meal, so that it can protect our precious farmlands from unscrupulous exploitation. This technology can also handle the cinder incinerated by the coal stone with a more environment-friendship way.The assumption in this dissertation is worthy of promoting and developing, but more research work and improvement have to be done to utilize coal stone successfully in cement factory.