Abstract
This paper aimed to study the effect of the polysulfide content on the micromorphology and spontaneous combustion characteristics of coal, in order to develop more targeted prevention and treatment strategies. To this end, this study selected the method of mixing different sulfides with very low sulfur content raw coal to prepare the coal samples to be tested. Various parameters, such as true density, porosity, micromorphology, and oxygen uptake of the different sulfur samples, were tested. The results reveal that sulfide had a certain expansion effect on the coal body and improved the pore structure of coal, and the porosity increased with the increase of the sulfur content. After adding iron (II) disulfide (FeS2) and iron (II) sulfide (FeS) powder to the original coal sample, the number of fine particles on the surface increased significantly. After increasing the oxidation temperature, the lamellar structure disintegrated, and the massive coal body was broken into several fine particles, which promoted the spontaneous combustion of coal. Polysulfide promotes the low-temperature oxygen absorption of coal and shortens the natural firing period of coal. FeS has a slightly greater effect on increasing the tendency of coal to spontaneously combust and shortening the shortest natural firing period of coal. Before the addition of FeS2 and FeS to the coal samples, the coal production amount was not much different below 80–90°C, and then, the gap gradually widened. Under the same temperature condition of coal, carbon monoxide (CO) production basically occurred first as the sulfur content increased. When FeS2 and FeS were added, the sulfur content of the coal samples was 3 and 4%, respectively, and the production of CO and ethene (C2H4) was the largest. Although the peak areas of aliphatic hydrocarbon, aromatic hydrocarbon, hydroxyl group, and carbonyl group in the coal samples with FeS were different, they all reached their maximum value when the sulfur content was 4%.
Highlights
Introduction e sulfur content inChina’s coal resources varies greatly, ranging from 0.04 to 9.62%
After the oxidation temperature increases, the lamellar structure is clearly disintegrated, and the block of coal is broken into numerous fine particles. e thin layer of fine particles loosens the structure of the coal seam and increases the air leakage velocity and oxygen content in micropores, further promoting the spontaneous combustion of coal
From the study of the effect of various sulfides on the physical structural properties of coal, such as porosity and microstructure, as well as its spontaneous combustion tendency, spontaneous combustion mark gas, and spontaneous combustion period, the following conclusions are drawn: (1) Sulfide can expand coal and improve its pore structure. e true density decreases with the increase of the sulfur content, while the porosity increases with the increase of the sulfur content
Summary
Is paper aimed to study the effect of the polysulfide content on the micromorphology and spontaneous combustion characteristics of coal, in order to develop more targeted prevention and treatment strategies To this end, this study selected the method of mixing different sulfides with very low sulfur content raw coal to prepare the coal samples to be tested. E experimental results of the true density test shown in Table 1 and Figure 3 reveal that the true density increases to varying degrees when FeS2 and FeS are added to the original coal samples before the increase of the oxidation temperature.
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