Sustainable preparation of high-calorific value and low-N and S energy products through the low-temperature alkali fusion of coal gasification fine ash

Zhichao Chen; Xiaodong Tian; Jian Hou; Zhengqi Li; Yongwei Xu; Yuanyuan Feng

doi:10.1016/j.envres.2023.116802

Sustainable preparation of high-calorific value and low-N and S energy products through the low-temperature alkali fusion of coal gasification fine ash

Environ Res. 2023 Nov 1;236(Pt 2):116802. doi: 10.1016/j.envres.2023.116802. Epub 2023 Aug 3.

Authors

Zhichao Chen¹, Xiaodong Tian², Jian Hou³, Zhengqi Li⁴, Yongwei Xu⁵, Yuanyuan Feng⁶

Affiliations

¹ School of Energy Science and Engineering, Harbin Institute of Technology, 92, West Dazhi Street, Harbin, 150001, PR China. Electronic address: chenzc@hit.edu.cn.
² School of Energy Science and Engineering, Harbin Institute of Technology, 92, West Dazhi Street, Harbin, 150001, PR China. Electronic address: xiaodongtian92@163.com.
³ School of Energy Science and Engineering, Harbin Institute of Technology, 92, West Dazhi Street, Harbin, 150001, PR China. Electronic address: 1481225826@qq.com.
⁴ School of Energy Science and Engineering, Harbin Institute of Technology, 92, West Dazhi Street, Harbin, 150001, PR China. Electronic address: green@hit.edu.cn.
⁵ Western Mining Group Technology Development Co., Ltd., Xining, 810000, PR China; State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, Gansu, 730000, PR China. Electronic address: xuyw21@lzu.edu.cn.
⁶ Western Mining Group Technology Development Co., Ltd., Xining, 810000, PR China. Electronic address: 1928627890@qq.com.

PMID: 37543129
DOI: 10.1016/j.envres.2023.116802

Abstract

Coal gasification fine ash (CGFA) is characterized by high yield, high carbon content, and difficult recovery. This results in waste of coal resources and serious environmental pollution. To address this issue, a novel green deashing process is proposed in this study to modify CGFA into deashed carbon (DAC) with a high calorific value and an ash content of less than 5% through a low-temperature alkaline fusion process. Compared with traditional alkaline fusion (which is carried out at 600-1000 °C), low-temperature alkaline fusion treatment can efficiently remove ash minerals in the temperature range of 300-450 °C, which is beneficial to the efficient recovery of residual carbon in DA, while simultaneously improving the physicochemical properties and energy characteristics of DAC, thereby improving its combustion performance. At an alkali fusion temperature of 350 °C, a NaOH:DA ratio of 4.5:1, and a reaction time of 40 min, the resulting DAC product had ash content of 2.28%, combustible material recovery (CMR) of 82.03%, higher heating value (HHV) of 31.07 MJ kg^-1, and S_BET of 445.43 m² g^-1. In comparison, it was found that low-temperature alkali fusion significantly improved the deashing of CGFA when compared to existing deashing technologies. These results strongly suggest that this innovative deashing method can modify CGFA into a high-calorific value and low-N and S fuel, thereby providing a cost-effective and sustainable utilization method for CGFA.

Keywords: Coal gasification fine ash; Deashing carbon; Energy products; Low-temperature alkaline fusion; Sustainable treatment.