PRODUCTION OF FORMED COKE FROM NIGERIAN COALS

Nigeria is endowed with large deposits of high grade iron ore but reserves of suitable coking coals areextremely meager necessitating looking into the option of utilising lower rank coals. In this work, theproperties of three Nigerian coals (Onyeama, Lafia-Obi and Garin Maiganga), are investigated to determinetheir suitability in developing formed coke for use as blast furnace coke. Parameters that wereused include the shatter index, expressed as percentage stability and friability and micum index. Thehighest cummulative percentage stability and the lowest cummulative percentage friability was observed inLafia-Obi with values of 67.54% and 32.46%, followed by Onyeama with 66.92% and 33.08% and thenGarin Maiganga with 55.04% and 44.96% respectiely. Medium and low temperature carbonization ofOnyeama and Lafia-Obi coal samples gave an improved and satisfactory percentage stability and friability forthe semi-cokes. The percentage stability and friability are indicators of charge performance in the furnaceand are within the range allowed for low shaft furnace except for Garin Maiganga whose stability indexis low. The micum index (I20), show that Lafia-Obi has the highest percentage of 31%, followed byOnyeama with 28%, and then Garin Maiganga with 23%. These show that Onyeama and Lafia-Obisemi-cokes have fair abrasive and impact resistance. Size consistency allows for good flow of gasesthrough the charge. The results obtained indicate that Onyeama and Lafia-Obi semi-cokes have reasonablestrength and hardness for use in the blast furnace.