Study of Lignite Upgrading by Using a Pulsing Air Riser
The lignite cannot be separated by traditional net coal preparation techniques for its easy sliming and difficulty of products dewatering subsequently. A dry process using the cylindrical pulsing air riser is tried to decrease the ash content, and then up
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(School of Chemical Engineering and Technology, Key Laboratory of Coal Processing and Efficient Utilization, China University of Mining & Technology, Xuzhou, Jiangsu 221116, China) Abstract: The lignite cannot be separated by traditional net coal preparation techniques for its easy sliming and difficulty of products dewatering subsequently. A dry process using the cylindrical pulsing air riser is tried to decrease the ash content, and then upgrade the lignite to effective utilization. The lignite sample was collected from a coal mine in Inner Mongolia, China. The proximate analysis of the lignite was tested, and the separation experiment of the -6+3mm size fraction lignite was conducted by the designed pulsing air riser system. The results show that the ash content of feed is reduced by 12%í15% and the separation efficiency is up to 43.11% under the conditions that air flow rate: 87m3/h; pulse frequency: 40Hz; feed speed: 400g/s and it can be realized by using cylindrical pulsing air Classifier in relatively short period of time The results show that CPAR could be efficiently used for the beneficiation of -6+3mm lignite of Inner Mongolia,China. Keywords: lignite; upgrade; pulsing air riser; dry coal separation; the air flow; the pulsing frequency; the feeding speed 1.Introduction The lignite reserves which have has been explored in China are more than 200 billion, accounting for 12.7% of the explored coal resources [1,2]. Reserve of lignite is rich and most of China’s lignite is distributed in the eastern area of Inner Mongolia. In the structure of Chinese energy, the coal is always the main body and the demand and supply of coal obviously increase with lignite. The supply of high rank coals, such as anthracite and bituminous coal, is gradually in short. Reserves of high rank coal are less gradually with the increase of exploitation, and energy problem is more serious. So the effective utilization of low rank coal of lignite is particularly important [3,4]. Lignite, with the features of low calorific value(about 13.0~27.2J/ kg), high volatile content (15%~40%), poor thermal stability, easy to spontaneous combustion, high moisture content and difficult storage and transportation, is not conductive to use [5]. 90% of China’s lignite is now used for power generation. Lignite has the features of easy to weathering and mud, and the price is low. Lignite is used directly as the fuel of power plant, without any separation process to upgrade its quality. Therefore, problems regarding the combustion and use of lignite should be solved and conducted in a more efficient and environmentally friendly way [6]. The processing and utilization of lignite would give priority to power generation. Countries with rich lignite resources like Australian, Germany, United States, Russia and Indonesia etc. all have successively carried out the study of processing and utilization technology of lignite [7,8]. Technologies of processing and utilization of lignite mainly include the lignite fluidized bed technology of Japan’s Mitsubishi heavy i
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