Effect of the Amount of Sludge on Physicochemical Properties and Chemical Structure of Low‐rank Coal under Hydrothermal Conditions

Abstract

Sewage sludge mixed with Yunnan low-rank coal was treated by hydrothermal treatment (HT) at mild temperature and high-pressure conditions. The fuel characteristics and chemical structure of HT solid products were investigated to explore the synergistic effects between low-rank coal and sludge. The results indicated that the fuel properties of HT solid products were negatively influenced as the amount of sludge increased, but there were synergistic positive effects on the content of volatile matter, fixed carbon, oxygen, and calorific value when the amount of sludge was more than 30 wt% in the HT at 300°C. More hydrogen groups in sludge were involved in the hydrogen transfer reactions between the low-rank coal and sludge, which promoted the occurrence of synergistic effects during the HT process. CO 2 and H 2 were the main gas products, but the yield of both gases produced by the HT of sewage sludge was significantly higher than that of low-rank coal. The aromaticity of HT solid products reduced from 60.65% to 51.83%, and the aliphaticity increased from 39.35% to 48.17% when the amount of sludge increased from 10 to 70 wt%.

High strength clean briquettes production from long‐flame coal fines by using polyvinyl alcohol and coal slime as binders

“…The automatic fully mechanized mining technology has been applied in Chinese coal mines for more than 40 years, which have provided technical support for safe, efficient, and sustainable development in coal industry. However, in this process, a large number of lump coals have been pulverized into coal fines, which cannot meet the requirements of various industrial production processes …”

“…However, in this process, a large number of lump coals have been pulverized into coal fines, which cannot meet the requirements of various industrial production processes. [1][2][3][4] According to the world energy outlook, approximately 400 million people still rely on the traditional use of coal for household combustion, and it is expected that the number would not decrease too much in the next two decades. 5 Only in China, about 29.5% of the rural households still utilized coal fines for cooking and heating, respectively.…”

Effects of activated carbon on optimization of microwave irradiation upgrading of Loy Yang lignite

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