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| Study on carbon oxidation process of coal gangue driven by heat and soil properties of its products |
| HU Han1, ZHANG Qing1,2, XIE Er-man1, ZHANG Xin-guang1, SONG Hao-ran1, TIAN Sen-lin1, HU Xue-wei1 |
1. Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming 650500, China;
2. Yunnan Coal Industrial Group Limited Co, Ltd., Kunming 650231, China |
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Abstract This study focused on the carbon-based minerals contained within coal gangue and subjected them to low-temperature thermal oxidation to investigate the effects of temperature and time on the conversion efficiency of these minerals and to understand the process by which the carbon-based components in coal gangue were converted into humus. After undergoing 1-3 hours of oxidation at medium and low temperatures (150~180℃), the dissolved organic carbon content of the coal gangue thermal oxidation products increased by more than 20times, from 8.76mg/L to 176.72mg/L. The proportion of organic carbon also increased fivefold, from 1.2% to over 6%, and the level of organic matter nutrients became comparable to that of grade 1soil as classified in soil survey nutrient categories. The enhancement in organic carbon content was attributed to the thermal oxidation process, which transformed the C-C and C=C bonds of the carbon-based minerals into C=O bonds, resulting in the formation of carboxyl and hydroxyl groups, as well as other functional groups. The carbon-based minerals underwent oxygen hydrolysis, leading to their transformation into humic substances such as fulvic acid. The increase in fulvic acid content was shown to effectively improve the moisture retention and aggregation performance of the coal gangue weathering products, enabling the products' water retention to exceed the standard for sandy soil and significantly boosting the biomass of winter pasture by 70%.
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Received: 16 January 2024
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