Review of the Preparation and Application of Porous Materials for Typical Coal-Based Solid Waste

Abstract

The discharge and accumulation of coal-based solid waste have caused great harm to the ecological environment recently. Coal-based solid wastes, such as coal gangue and fly ash, are rich in valuable components, such as rare earth elements (REY), silicon dioxide, alkali metal oxides, and transition metal oxides, which can be used to synthesize various functional Si-based porous materials. This article systematically summarizes the physicochemical characteristics and general processing methods of coal gangue and fly ash and reviews the progress in the application of porous materials prepared from these two solid wastes in the fields of energy and environmental protection, including the following: the adsorption treatment of heavy metal ions, ionic dyes, and organic pollutants in wastewater; the adsorption treatment of CO2, SO2, NOx, and volatile organic compounds in waste gas; the energy regeneration of existing resources, such as waste plastics, biomass, H2, and CO; and the preparation of Li–Si batteries. Combining the composition, structure, and action mechanism of various solid-waste-based porous materials, this article points out their strengths and weaknesses in the above applications. Furthermore, ideas for improvements in the applications, performance improvement methods, and energy consumption reduction processes of typical solid-waste-based porous materials are presented in this article. These works will deepen our understanding of the application of solid-waste-based porous materials in wastewater treatment, waste gas treatment, energy regeneration, and other aspects, as well as providing assistance for the integration of new technologies into solid-waste-based porous material preparation industries, and providing new ideas for reducing and reusing typical Chinese solid waste resources.

Estimation of Chemical and Mineral Composition, Structural Features, and Pre-Firing Technological Properties of Waste Coal Heaps for Ceramic Production

“…However, when firing these samples, they show a sufficiently high strength. At the same time, the strength of the fired samples strongly depends on the initial raw material degree of grinding and the firing temperature [32][33][34][35][36]. Groups by mechanical bending strength in dry state are given in Table 6.…”

Study on the macro–micro evolution of compaction characteristics of coal gangue with different grain sizes under side-limit compression conditions

“…With the long-term sustained development of coal resources, the continuous underground coal mining activities have caused surface subsidence and accumulation of coal gangue waste, which has seriously affected coal mining and caused serious pollution to the living environment in mining areas 1 – 4 . Fill mining, as a green mining technology, utilises coal gangue underground for filling in order to reduce problems such as difficulty in accumulating coal gangue on the surface and pollution of the environment, to improve the recovery rate of coal resources and to control surface subsidence 5 – 7 . In the process of filling and mining, the gangue pressure-bearing deformation characteristics of the quality and effect of filling and mining has a decisive impact, directly affecting the surface subsidence and roof control and other engineering problems, need to carry out in-depth research on its characteristics to ensure the safety of filling and mining operations 8 – 11 .…”

Solidification and Release Characteristics of Heavy Metals in Gypsum from Coal-Fired Power Plants

“…Previous research has focused on the solidification of heavy metals in fly ash and desulfurization wastewater from coal-fired power plants, with chemical solidification being the more common method recently [7,8,[12][13][14][15][16]. Chelating agents are gradually being used to chelate heavy metals in wastewater due to their better effectiveness at solidifying them.…”