Variation of Sulfur Content in Coking Coal as Function of Its Particle Size
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ariation of Sulfur Content in Coking Coal as Function of Its Particle Size X. G. Mua,*, Z. X. Jina,b,**, C. B. Denga,b,***, and F. Gaoa,c,**** a
College of Safety Science and Engineering, Liaoning Technical University, Fuxin, 123000 China b School of Safety and Emergency Management Engineering, Taiyuan University of Technology, Taiyuan, 030024 China c Shanxi Coking Coal Group Co., Ltd, Taiyuan, 030024 China *e-mail: [email protected] **e-mail: [email protected] ***e-mail: [email protected] ****e-mail: [email protected] Received January 12, 2020; revised March 5, 2020; accepted June 3, 2020
Abstract—To understand quality of coking coal possessing different particle sizes, coal samples from Gao Yang (GY) and Shui Yu (SY) mines were systematically studied. The samples had wide particle size variations with six distinct ranges. The main emphasis was placed on analyzing sulfur and coke contents as function of particle sizes. X-ray photoelectron spectroscopy (XPS) was used to analyze sulfur content as well as its chemical state. Sulfur coordination and group geometry was analyzed by Fourier transform infrared spectroscopy (FTIR). Scanning electron microscopy (SEM) was applied to characterize surface morphology. Sieving of the coal samples increased ash and sulfur contents in all fractions. Organic sulfur was mostly present as thiophene for all particle size ranges. Macromolecular structure of coal was almost the same for all samples. Changes in total sulfur content of different coal fractions were mainly caused by the variations in inorganic sulfur concentrations because organic sulfur content remained almost constant. Understanding particle size distribution in different coals is important for selecting and optimizing appropriate desulfurization methods. Keywords: Coking coal, Organic sulfur, Coal particle size, XPS, SEM, FTIR DOI: 10.3103/S0361521920050079
1. INTRODUCTION Coal is a complex and ununiform mixture of organic and inorganic compounds [1]. Sulfur present in coal can be of organic or inorganic origin [2]. Presence of inorganic sulfur in coal is due to the sedimentary environment of the coal seam, the degree of reduction and the degree of iron ion (Fe2+ and Fe3+) enrichment around the coal seam. The major inorganic sulfur containing species in coal are pyrite, sulfates, elemental sulfur and sulfides [3].Origin of organic sulfur in coal is from plants and microbial proteins, which participated in coal formation. Organic sulfur is actually chemically incorporated into the macromolecular structure of coal [4]. However, sulfur presence is detrimental to the coking coal quality because it negatively affects properties of the resulting steel [5]. The level of coke sulfur directly affects the
production of blast furnace ironmaking, and the product with sulfur content greater than 0.07% is waste. Moreover, in China, the price difference between high sulfur coal (S > 1.5%) and low sulfur coal (S < 1.0%) is very large. Therefore, to meet coking requirements and the rational use of resources, sulfur content in coal
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