A novel process to recycle coal gasification fine slag by preparing Si-Fe-Al-Ca alloy. (1st July 2023)

• Record Type: Journal Article
• Authors: Wang, Yaoxuan; Zhang, Zhaoyang; Li, Lamei; Guo, Xiaolin; Wei, Donghui; Kong, Jian; Du, Hongbing; Wang, Hong; Zhuang, Yanxin; Xing, Pengfei
• Is Part Of: Journal of environmental management. Volume 337(2023)
• Publication Date: 2023-07-01
• Subjects: Coal gasification fine slag -- Si–Fe–Al–Ca alloy -- Carbothermal reduction -- Recycling -- Solid waste; Environmental policy -- Periodicals; Environmental management -- Periodicals; Environment -- Periodicals; Ecology -- Periodicals; 363.705
• DOI: 10.1016/j.jenvman.2023.117681
• Languages: English
• ISSNs: 0301-4797

Abstract

Abstract: Maximizing the use of valuable components in coal gasification slag is of great significance for resource recovery and the environment due to the huge annual emission of coal gasification slag. This study successfully produced Si–Fe–Al–Ca alloy with a composition of 63.83 wt% Si, 19.73 wt% Fe, 7.09 wt% Al, 6.32 wt% Ca, 1.70 wt% Ti, 0.03 wt% P, 0.66 wt% Mn, 0.05 wt% Cr, 0.53 wt% C, and 0.06 wt% others through electric arc furnace smelting from mixed coal gasification fine slag. The alloy composition is close to the standard 65% ferrosilicon, which can be used in the deoxidation of the molten steel industry. Moreover, the alloy yield was increased from 20.53% to 67.78% by using the residual carbon of the coal gasification slag as the reductant directly instead of adding petroleum coke. The transformation of coal gasification fine slag during the smelting process and the formation mechanism of the alloy were studied and the carbothermal reduction mechanism of Al2 O3 and CaO can be explained by the reduction and decomposition theory of carbides. The complex liquid phase of the reactant system and product system in the smelting process made the carbothermal reaction of Al2 O3 and CaO easier to occur, but it also brought the problem that the reactions were not fully completed. Graphical abstract: Image 1 Highlights: Propose a new method for recycling coal gasification fine slag. The residual carbon of coal gasification slag has high reactivity. The transformation mechanism of Ca and Al in the reaction was investigated. The recycling process is simple, efficient, and economical. The method provides a theoretical basis for industrial-scale production.