Structural Evolution Characteristics Of Kuche Coal From Northwestern China During Modification Pyrolysis And Its Application In Coal Blending And Coking

The coal resource reserve is rich in China,but the high-quality coking coal resources,about 27%,is rare.With the rapid development of iron and steel industry in recent decades,coking coal resources have been overexploited,and high-quality coking coal resources are exhausting.However,Northwest China is rich in coal resources and has a variety of coking coals.The coking coals obtained from Northwest China can't be vastly used in coal blends to manufacture metallurgical coke due to the subsequent coke with high reactivity and low strength after reaction.Therefore,local coking plants have to buy coking coal of high-quality from the mainland,which leads to increase the coking costs.To solve this problem,it is urgent to carry out the research on the modified low-quality coking coal from Northwest China to produce high strength metallurgical coke.In this paper,firstly,the coal quality and pyrolysis characteristics of low-quality KC fat coal from Northwest China were analyzed,and then the evolution characteristics of microcrystalline structure during pyrolysis process were also investigated.At lastly,the influence of modifier(ZBS)on the pyrolysis process of KC fat coal was studied.According to the pyrolysis behavior of KC fat coal,a variety of coking experiments from low-quality coal were carried out.Besides based on the pyrolysis characteristics of coal,the modification mechanism of ZBS was deeply investigated.The main conclusions are as follows:(1)Temperature is beneficial to increase the degree of graphitization of coal chars.When the pyrolysis temperature is 300-750?,the disorder degree of coal char structure increases,and the degree of graphitization decreases;when the pyrolysis temperature is750-1050?,the order degree of coal char structure increases,and the degree of graphitization increases.(2)Adding ZBS pulverized coal modifier can help to increase the content and order degree of coal char microcrystalline structure.The modifier can slow down the pyrolysis reaction rate of coal in the middle and low temperature range of 300-750?,and promote the polycondensation of coal powder in the high temperature range of750-1050? to increase the degree of condensation polymerization of aromatic compounds.At 900-1050?,the degree of coke graphitization increases.(3)High-strength metallurgical coke can be obtained by carrying out coking tests on low-quality coal in the northwest region through upgrading and blending.It shows that ZBS pulverized coal modifier can greatly increase coke strength and reduce coke reactivity.(4)Provided Haohai Coal Chemical Co.,Ltd.with a large proportion of coal blending schemes using local coal resources in the northwest,namely Qiuci QM: Jingtai JM: Main Coke: Baicheng SM: Heiyan quan QM: 11# QM: Wuhai FM : Kuche FM =17%: 5%: 15%: 20%: 5%: 15%: 20%: 3%.The CRI of coke is reduced to 26%,and the CSR is increased to 64.56%,and the quality reaches the national first grade metallurgical coke standard.At the same time,an optimization test was carried out,and the best blending amount of ZBS pulverized coal modifier was 0.3%.