Energy & Fuels 2007, 21, 419-425
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Pyrolysis of Collie Coal Briquettes To Produce Char as a Metallurgical Reductant† Kongvui Yip,‡ Hongwei Wu,*,‡,§ and Dong-ke Zhang‡ CRC for Coal in Sustainable DeVelopment, Centre for Fuels and Energy, and Department of Chemical Engineering, Curtin UniVersity of Technology, GPO Box U1987, Perth, Western Australia 6845, Australia ReceiVed August 20, 2006. ReVised Manuscript ReceiVed September 30, 2006
Western Australia lacks coking coal but has a substantial reserve of high-moisture sub-bituminous coal of noncoking nature in the Collie basin. To diversify Collie coal uses, one desirable option is to briquette the coal followed by pyrolysis to make char as a metallurgical reductant, thus extending the applications of Collie coal to the metallurgical industry. This study investigates the pyrolysis behavior of Collie coal briquette and determines the optimal pyrolysis conditions to produce char from Collie coal briquette as a potential reductant for metallurgical applications. Collie coal briquettes formed using a patented binderless briquetting process were pyrolyzed in a laboratory furnace at temperatures ranging from 500 to 1400 °C with a heating rate of 10 °C min-1 and a holding time of 1 h at the peak pyrolysis temperatures. The corresponding briquette fines were also pyrolyzed to study the importance of transport effect during pyrolysis of the large briquettes. The pyrolysis time needed for complete devolatilization was found to be well less than the 1 h holding time employed. As expected, the briquette char yield and reactivity decrease with an increasing pyrolysis temperature. The mechanical strength of the char initially increases with the pyrolysis temperature, levels off at around 1000 °C, and then decreases with a further temperature increase. Dependent upon the pyrolysis temperature, briquette chars generally have low contents of ash (
