Study On Increasing The Usage Of Non-coking Coal In Coke-Making By Adding Coal Modifying Additive Into Coal Blend

Coking coal prices rose substantially in domestic and international marketing in the recent years. Good quality coking coal is becoming fewer and fewer but coking coal quality showed a downward trend by and by, it bring about a more and more serious contradiction between the supply of coking coal and the quality of coke. Researchers are seeking the means of coke coal quantity improvement for using non-coking coal totally or partly replace the costly coking coal.The coking test was conducted on 40 kg coking-oven in Nanjing Iron & Steel United Co., Ltd. with a new coal modification technology. The coking raw materials include the independent R&D coal modifying additive(ZZZ) and blend coal A and non-coking coal (hard coal and one kind of bituminous coal using as pulverized coal on blast furnace of Nanjing I&S Co), Firstly the coal modifying additive was mixed into non-coking coal at various ratios, then they were mixed into blend coal A. The test results are shown as follows:â‘ Analyzing the indexes of mixed coal quality indicate that the yields of volatile in coal blend with all additions were decline slightly, yields of ash and sulfur in coal blend with all additions are essentially unchanged, the caking properties index of mixed coal was improved obviously. Proximate analysis of coke indicated that the yields of volatile in coke are decline slightly, yields of ash and sulfur in coke are essentially unchanged, and yields of fixed carbon in coke are also essentially unchanged.â‘¡The optimal size of hard coal is less than 3 mm and 70% of which is less than 1mm. Proximately 85% of the bituminous used to spew in BF have a particle size less than 3 mm.â‘¢Modifying the property of non-coking coal by adding zzz. The crushing strength and wear-resistant strength of coke were improved obviously. The usage of non-coking coal was increased by 15% and adding 0.10% of coal modifying additive. The coke quality produced from coal blend with zzz comparing with the coke quality produced from coal blend without zzz. The crushing strength of coke is increased by 14.35 percentage points, Wear-resistant strength of coke is reduced by 6.0 percentage points, The reactivity is reduced by 5.5 percentage points,and the strength after reaction is increased by 5.93 percentage points. The experimental results of 40kg coke oven show that metallurgical coke cold strength and thermal index are similar to the coke quality produced from coal blend in producing of Nanjing Iron & Steel United Co..â‘£The results of industrial experiments is consistent with the results of little iron box test. The proportion of coking coal and fat coal is decreased but the proportion of inferior coal is increased by thirty-five percent points in coal blending scheme, After adding zzz by 0.10%, The properties index of coke could meet the coking plant standard.