Study On The Basic Properties And Utilization Of Low Ash And Low Sulfur Non-caking Coals

Three kinds of low rank bituminous coals(Dongsheng, Shenmu and Fugu long flame coal) were researched on the analysis of basic properties, physical properties, structural parameters and technological characteristics in this paper. Those coals were compared the difference of micro structure and macro properties with gas coal, in order to provide theoretical guidance for the subsequent preprocessing. The aim was adopt the method of rapid heating pretreatment to decrease the oxygen content and volatile matter yield of flame coal based on the difference of oxygen content, oxygen functional group and structures with gas coal. The pretreatment effect was analyzed the coke quality through coal blending and coking.The basic properties analysis showed that the low rank bituminous coal contains high moisture, high oxygen content, and non-caking, while it had the advantages of low ash, low sulfur. The infrared spectrum of low rank bituminous coal would be similar to gas coal, while the absorption peak of linkage was only observed in the gas coal and its tailings. The acid oxygen containing functional groups was more than several times to gas coal, and the phenol hydroxyl become mainly acid oxygen containing functional groups with the increasing the coal rank. On the physical structure, the true density, apparent density were similar to different coal rank coals, but the porosity of gas coal was biggest and the pore structure were developed, while the porosity, aperture and hardness of low rank bituminous coal were less than those of gas coal, and the grind ability index was better than those of gas coal. The results indicated that the structure of gas coal is more compact. 1H-NMR analysis indicated that the hydrogen of gas coal which linked with aromatic side chain α carbon atoms more than flame coal, the hydrogen linked aromatic side chain β beyond carbon atoms is less than flame coal. The fa(aromatic carbon ratio) and σ(aromatic ring substitution) of four coal samples were close, while the different of Haru/Car(aromatic ring condensation) were observed. The Haru/Car of Dong Sheng coal is the largest. XRD diffraction showed the Bragg angel of 002 peak increase with the coal rank increasing, which would be made the gas coal’s lamellar spacing of aromatic less than flame coal.The experiment of coal blending and coking showed that the low rank coal would be blend in coking had an disadvantage the caking properties of mixed coal, the caking index decreased significantly, and not a linear variation. Otherwise, there had a greater impact on the maximum expansion(b) for caking coal when it blend the low rank bituminous coal, the influence weakened for medium caking coal. The same rules were observed by Gieseler fluidity test. The performance of coke adding pretreatment of coal would be better than directly adding the low rank bituminous coal. the volatile and oxygen content of pretreatment coal would be controlled low level which would be help to increase the CSR, micro hardness and improve coke optical texture, and decrease the CRI.