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Review

Resource Recycling and Ceramsite Utilization of Coal-Based Solid Waste: A Review

by
Han Wang
1,
Chunfu Liu
1,2,*,
Chenyu Zhu
1 and
Zhipeng Gong
1
1
School of Materials Science and Engineering, Anhui University of Science and Technology, Huainan 232001, China
2
Anhui Engineering Research Center for Coal Clean Processing and Carbon Emission Reduction, Anhui University of Science and Technology, Huainan 232001, China
*
Author to whom correspondence should be addressed.
Minerals 2025, 15(9), 948; https://doi.org/10.3390/min15090948
Submission received: 28 July 2025 / Revised: 26 August 2025 / Accepted: 3 September 2025 / Published: 5 September 2025
(This article belongs to the Special Issue Recycling and Utilization of Metallurgical and Chemical Solid Waste)
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Abstract

Coal-based solid waste refers to solid waste generated during coal mining and washing processes, and is one of the major types of industrial solid waste in China. Its resource utilization is a critical part of the clean and efficient use of coal, and preparing ceramsite from coal-based solid waste is an important means to promote its “resourceful, large-scale, and high-value” utilization. This paper systematically summarizes the types and properties of coal-based solid waste, its resource utilization methods, and research progress in ceramsite preparation. The focus is on assessing the feasibility, process features, and application status of ceramsite made from coal-based solid waste in areas such as construction, heavy metal stabilization, and water treatment. Using coal-based solid waste to produce ceramsite offers cost reduction and pollution mitigation benefits while showcasing significant potential for resource recycling and sustainable development. This paper further outlines the development trends and technological innovation directions for coal-based solid waste ceramsite, providing theoretical support and practical guidance for advancing the resource utilization of industrial solid waste.

1. Introduction

Coal-based solid waste refers to the solid waste produced during the mining and washing processes of raw coal, notable for its large volume, complex composition, and difficulty in treatment, primarily comprising coal gangue, fly ash, coal gasification residue, and coal slurry [1,2]. Based on the “Annual Report on Coal Industry Development” issued by the China National Coal Association, the trends in raw coal output, raw coal for washing, and the washing rate in China from 2015 to 2024 are shown in Figure 1. In 2024, China’s raw coal output was 4.76 billion tons, with a washing rate of 68.0%. With the degradation of raw coal quality and the advancement of mining mechanization, the annual production of coal-based solid waste continues to rise. The accumulation of coal-based solid waste consumes substantial land resources and results in the leaching and emission of hazardous substances, including heavy metal ions, posing severe threats to the environment and human health [3,4]. In recent years, with the continuous advancement of clean and efficient coal utilization and the gradual implementation of the “carbon peaking” and “carbon neutrality” goals, the resource utilization of coal-based solid waste has received increasing attention. And the large-scale and high-value utilization of coal-based solid waste represents both a critical environmental protection effort and a key strategy for advancing the circular economy.
Ceramsite is made from clay, shale, and industrial solid waste as the main raw materials. It involves shaping and granulating powdery materials, followed by firing, cooling, or direct non-sintering to produce lightweight, porous silicate spheres or ellipsoids with certain strength [5]. As an environmentally friendly material, researchers are exploring the use of industrial solid waste to prepare ceramsite for applications in building materials, landscaping, water treatment, and other fields increasingly [6,7,8,9]. This paper aims to review and summarize the feasibility of resource utilization of coal-based solid waste, particularly in its application for ceramsite preparation. By thoroughly analyzing and summarizing domestic and international research, this paper explores the potential application value and technological innovations of coal-based solid waste in ceramsite preparation. It emphasizes the advantages of coal-based solid waste in ceramsite production and proposes future development priorities and directions, providing a reference to promote the resource utilization of industrial solid waste and contribute to resource recycling and environmental sustainability.

2. Current Status of Coal-Based Solid Waste Resource Utilization

2.1. Types and Properties of Coal-Based Solid Waste

Gaining insight into the types and characteristics of coal-based solid wastes is crucial for developing effective resource utilization strategies. Coal gangue, fly ash, coal gasification slag, and coal slime demonstrate considerable variation in physicochemical properties, formation mechanisms, and potential for utilization.
Coal gangue is a solid waste generated during raw coal extraction, washing, and processing, and is one of the most common types of mining solid waste [10]. It encompasses the rock layers associated with coal seams, the interlayered stones excavated during coal extraction, and the inorganic impurities removed during coal washing. The yield of coal gangue accounts for 10% to 15% of the raw coal mining and washing process, making it one of the largest industrial waste streams in China [11,12]. China has approximately 1500 to 1700 coal gangue heaps, with a total cumulative volume exceeding 6 billion tons. Furthermore, this volume continues to grow at an annual rate of 500 to 800 million tons [13].
Fly ash is a type of slag produced during coal combustion, primarily originating from coal-fired power plants and industrial boilers [14,15]. During combustion, the intense heat causes portions of the inorganic matter in coal to melt or vaporize. As the material cools and condenses within the furnace, it forms fine particles that settle on flues or collection devices, resulting in the generation of fly ash. The volume of fly ash production is immense; globally, approximately 800 million tons are generated annually, with China alone accounting for over 500 million tons. This extensive production poses significant environmental challenges, including land occupation, dust pollution, and the potential leaching of heavy metals.
Coal gasification slag is a solid waste produced during the coal gasification process, emerging as a byproduct when coal is converted into gaseous fuels using gasification technology [16]. In China, more than 70 million tons of gasification slag are generated annually, with only a small fraction being effectively utilized. The majority is disposed of through landfilling and piling, practices that consume significant land resources and pose risks of secondary contamination to groundwater and soil [17,18].
Coal slurry is a byproduct produced during the coal washing and processing stages. It consists of fine coal particles, mineral impurities, and water, typically existing in a muddy or slurry-like state. Its high moisture content, high viscosity, high ash content, and low calorific value [19,20], have historically posed significant challenges to effective utilization. With the expansion of raw coal washing operations and advancements in coal mining mechanization, the output of coal slurry has been steadily increasing.
Based on the above analysis, the massive generation of coal-based solid wastes is accompanied by severe environmental risks, such as heavy metal leaching, groundwater contamination, and dust pollution. However, their mineral composition and physicochemical properties offer vast potential for resource recovery and sustainable utilization.

2.2. Methods of Resource Utilization of Coal-Based Solid Waste

China’s coal industry is currently transitioning toward low-carbon and environmentally friendly development. The coal-based solid wastes, rich in recoverable resources, represent a critical pathway for advancing the national “carbon peak” and “carbon neutrality” goals. Details on specific utilization modes and features of typical coal-based solid wastes are provided in Table 1.

3. Recent Progress in Ceramsite Derived from Coal-Based Solid Wastes

3.1. Present Situation of Ceramsite Preparation

At present, the preparation methods of ceramsite can be divided into sintering preparation and non-sintering preparation as illustrated in Figure 2.
Sintering preparation involves mixing raw materials and subjecting them to high temperatures to form a uniform particle structure. Sintering is a critical step in the production of sintered ceramsite, as high-temperature sintering facilitates bonding between ceramsite particles, thereby improving their mechanical properties and stability. Additionally, the appropriate proportioning of raw materials is essential for optimizing the performance of ceramsite. The configuration of process parameters, such as preheating temperature, preheating duration, rate of temperature increase, calcination temperature, and calcination time, significantly influences the properties of the final product [42]. Compared to sintered ceramsite, non-sintered ceramsite incorporates an aging process and replaces calcination with curing. These processes significantly enhance the stability and durability of the ceramsite, resulting in improved mechanical properties and a longer service life [43]. The production of non-sintered ceramsite eliminates the need for high-temperature sintering, thereby conserving energy and reducing environmental pollution [44]. In practical applications, the process flow is adjusted and optimized according to the specific raw materials and product requirements.

3.2. Feasibility Analysis of Preparing Ceramsite from Coal-Based Solid Waste

Traditionally, ceramsite is produced by sintering expanded clay or shale at temperatures ranging from 950 to 1300 °C. However, with the continuous depletion of natural resources in recent years, developing alternative raw materials has become essential to sustain ceramsite production [45,46]. Coal-based solid waste, which contains a high proportion of silica and alumina—the primary raw materials required for ceramsite production—offers a viable solution. Additionally, coal-based solid waste is characterized by high output and low cost. Utilizing it as a raw material for ceramsite production not only significantly reduces costs but also mitigates the environmental impact associated with improper disposal. This approach provides substantial economic and social benefits, contributing to resource recycling and promoting sustainable development.
The preparation technology of ceramsite demonstrates significant advantages in the resource utilization of coal-based solid wastes. Using coal gangue and municipal sludge as the main raw materials, high-performance ceramsite meeting environmental safety standards can be prepared through scientific proportioning and optimization of process conditions, showing remarkable efficacy in stabilizing heavy metals and reducing ecological and health risks [47]. Furthermore, using fly ash as a raw material and combining it with a molding process effectively addresses the high loss on ignition of traditional ceramsite and validates its environmental friendliness through density functional theory analysis. The optimized ceramsite preparation process immobilizes heavy metal ions and other harmful components in stable phases, thereby significantly reducing their leaching levels, while reducing resource consumption and mitigating environmental risks [48]. These findings demonstrate that ceramsite preparation technology facilitates the efficient resource utilization of coal-based solid wastes, offering a viable pathway for environmental conservation and the advancement of a circular economy.
The physicochemical properties of coal-based solid waste ceramsite are stable, making it resistant to leaching or decomposition. Additionally, the production and application of coal-based solid waste ceramsite adhere to environmental standards, stabilizing inherent heavy metal ions during production. In adsorption applications, it efficiently removes pollutants, contributing to the purification of water, air, and soil, while avoiding environmental contamination and supporting environmental protection and resource utilization. According to the Riley ternary phase diagram, the optimal composition for ceramsite preparation should consist of SiO2 (40%–79%), Al2O3 (10%–25%), and fluxing agents (13%–26%, including CaO, MgO, Na2O, and K2O) [49]. This composition enables the successful preparation of ceramsite by forming a liquid phase with appropriate viscosity. Coal-based solid wastes have high SiO2 and Al2O3 contents and contain certain fluxing components, aligning their composition with the optimal range for ceramsite in the Riley phase diagram, making them ideal raw materials for ceramsite production. In China, this technical feasibility has already been demonstrated on an industrial scale. For example, the “WS·DYNASI” ceramsite process developed by Inner Mongolia Zhengtang Environmental Industry Co., Ltd. (Baotou, China) has been applied using fly ash and coal gangue as raw materials. A demonstration line at the Baotou Donghua Thermal Power Plant achieved an annual capacity of 100,000 m3 ceramsite, consuming approximately 120,000 tons of fly ash and 5000 tons of coal gangue per year. The product has been successfully applied as a bio-ceramsite filter medium in wastewater treatment plants, fully demonstrating the feasibility and practical value of coal-based solid wastes in engineering practice.
The chemical composition of typical coal-based solid wastes from different regions in China is shown in Table 2.

3.3. Application Status of Coal-Based Solid Waste Ceramsite

3.3.1. Application in the Field of Construction Materials

Ceramsite, due to its characteristics of low density, high strength, and durability, has found extensive application in concrete production [63]. According to different engineering requirements, ceramsite can serve as lightweight coarse and fine aggregate to replace part of the natural aggregate, effectively reducing the overall density of concrete; at the same time, it can also partially replace cement, thereby reducing cement consumption, lowering carbon emissions, and optimizing the microstructure of concrete [64]. Furthermore, ceramsite is commonly applied as a filling material in concrete, where it improves pore distribution and connectivity, thereby enhancing the material’s density and durability [65]. Especially in the production of lightweight concrete, the enclosed porous structure of ceramsite allows for a substantial reduction in concrete’s self-weight while still preserving considerable compressive strength and sound mechanical performance [66]. In terms of durability, the unique porous structure of ceramsite plays a crucial role. On the one hand, this structure can form a uniformly distributed pore system inside the concrete, improve stress distribution, and partially mitigate the propagation of microcracks caused by temperature variations or applied loads, thereby enhancing the crack resistance and freeze–thaw performance of concrete [67,68]. On the other hand, the buffering space formed by the internal pores of ceramsite can effectively hinder the rapid penetration of harmful external agents (e.g., chloride ions, sulfates), slow down the transport process of aggressive ions, and thus improve the chemical resistance of concrete [69]. Economically, while the production of ceramsite may raise the initial material cost, its benefits in reducing structural loads and prolonging service life substantially improve overall cost efficiency [70]. Moreover, utilizing coal-based solid wastes for ceramsite production not only facilitates resource recycling but also mitigates environmental impacts, thereby further supporting the principles of sustainable building development.
The research and development of ceramsite technology have provided a new pathway for the resource utilization of industrial wastes and achieved significant progress in the preparation and performance optimization of functional materials. Foam ceramics with excellent properties can be produced at a graphite tailings: coal gangue: potash feldspar ratio of 40:50:10, showing a bulk density of 0.749 g/cm3, compressive strength of 12.37 MPa, thermal conductivity of 0.21 W/(m·K), and a water absorption as low as 0.79% [71]. Honeycomb ceramsite prepared from sand washing sludge and coal fly ash exhibited low density (733.2–968.3 kg/m3), high strength (11.2–18.8 MPa), and low water absorption (1 h water absorption of 1.2%–2.8%). Compared with concrete prepared using commercial ceramsite, lightweight aggregate concrete made with this ceramsite demonstrated higher compressive strength and lower thermal conductivity [72]. The synergistic utilization of circulating fluidized bed (CFB) fly ash and sludge also yielded favorable results. With coal fly ash at 65%–80% and sludge at 20%–35%, ceramsite sintered at 1200–1250 °C achieved a bulk density of 750–850 kg/m3, compressive strength of 5.11–7.86 MPa, and water absorption as low as 0.27%–0.94% [73]. In addition, high-performance porous ceramics can be obtained from a composite system of coal gangue, fly ash, and silica sand without additional additives. Among them, the sample with a ratio of 48:32:20 performed best, with a bulk density of only 0.67 g/cm3, a porosity as high as 74.9%, a compressive strength of 6.9 MPa, and excellent acid resistance [74]. These findings provide a robust foundation for the broader application of ceramsite technology in construction and environmental sectors, while facilitating efficient solid waste resource utilization and fostering the growth of a circular economy.

3.3.2. Application in the Field of Heavy Metal Immobilization

The immobilization of heavy metals in coal-based solid waste ceramsite is governed by multiple synergistic mechanisms, such as physical encapsulation, ion exchange, chemical precipitation, and lattice incorporation. In the sintering process, the mobility of molten glass phases combined with the crystallization of new phases enhances the densification of the matrix, entrapping heavy metals within low-permeability glassy or crystalline phases and thus building a physical barrier that markedly lowers the leaching risk. Meanwhile, aluminosilicate and Ca- or Fe-bearing mineral phases provide abundant exchangeable sites, enabling heavy metal cations to be incorporated into the mineral matrix through ion exchange, thus achieving stable fixation. Furthermore, the sintering process promotes the formation of thermodynamically stable mineral precipitates, transforming heavy metals into sparingly soluble phases that strengthen long-term stability. A more durable fixation mechanism is realized through isomorphous substitution or solid solution, whereby heavy metal ions occupy lattice positions and remain stably incorporated. These mechanisms often occur simultaneously at different stages and reinforce one another, thereby significantly reducing the mobility and bioavailability of heavy metals [75,76,77]. As shown in Figure 3, ceramsite immobilizes arsenic into stable mineral phases, thereby reducing leaching and enhancing environmental safety.
Ceramsite preparation technology has become an important direction for the resource utilization of coal-based solid wastes, demonstrating diversified raw material options and significant environmental friendliness. Ceramsite prepared using fly ash, biomass ash, and sludge ash as main raw materials exhibits excellent performance under optimized process conditions, featuring low bulk density, high compressive strength, and low water absorption. Additionally, its heavy metal leaching concentrations are far below national standard limits, indicating effective heavy metal stabilization and environmental safety [78]. Moreover, high-strength ceramsite prepared from coal gangue and dyeing sludge achieves effective heavy metal fixation through sintering, significantly reducing the toxicity of raw materials while enabling safe recycling and utilization [79].
To address the demand for lightweight materials, lightweight ceramsite made from fly ash, waste oil sludge, sediment, and SiC foaming agents features low bulk density, high porosity, and superior water absorption. It effectively immobilizes hazardous elements in the raw materials, maintaining heavy metal concentrations below national standards and preventing secondary contamination [80]. In contrast, non-sintered ceramsite prepared from coal gasification slag further reduces production costs, with compressive strength and water absorption meeting national standards, and heavy metal leaching concentrations significantly reduced, highlighting the economic and environmental advantages of this approach [81]. These technological pathways provide diversified options for the efficient resource utilization of coal-based solid wastes, while promoting green development in the industrial solid waste treatment sector.

3.3.3. Application in the Field of Water Treatment

The study demonstrates that this method effectively stabilizes heavy metals and promotes the resource utilization of coal gasification slag, offering a cost-effective and environmentally sustainable solution for industrial waste management [82]. Compared to traditional methods, ceramsite, as a novel adsorbent material, offers significant advantages. Its larger specific surface area and higher porosity provide abundant adsorption sites, enabling the efficient removal of heavy metal ions from water. Moreover, its excellent chemical stability and corrosion resistance ensure consistent adsorption performance, minimizing the risk of heavy metal leaching [83,84]. Figure 4a shows the evolution of pore structures in ceramsite during the sintering process, while Figure 4b presents the internal pore architecture of the ceramsite.
The adsorption mechanisms of ceramsite primarily include physical adsorption, chemical adsorption, and surface complexation. The adsorption mechanism of ceramsite is shown in Figure 5.
Physical adsorption involves the adherence of pollutants onto the surface of ceramsite through van der Waals forces. This process is primarily influenced by the surface area and pore structure of the ceramsite, making its specific surface area and porosity critical factors in determining its adsorption capacity. While physical adsorption demonstrates low selectivity for pollutants, it offers strong performance in terms of overall adsorption capacity [88]. Chemical adsorption involves the formation of chemical bonds between active sites on the ceramsite surface and pollutants, making the process typically irreversible. The adsorption mechanism is driven by interactions between functional groups on the ceramsite surface and pollutants, resulting in high selectivity. This allows for the effective removal of specific contaminants, such as heavy metal ions. Chemical adsorption generally occurs as a monolayer process and involves higher adsorption energy, providing better stability and longer-lasting adsorption effects. Surface complexation is an adsorption mechanism in which complexes form between functional groups on the ceramsite surface and metal ions, primarily describing the adsorption of heavy metal ions. During this process, functional groups such as hydroxyl and carboxyl groups on the ceramsite surface form stable coordinate bonds with metal ions, effectively immobilizing the heavy metals and reducing their bioavailability.
The functional development and utilization of ceramsite hold significant importance in the high-value utilization of coal-based solid wastes, particularly demonstrating broad application prospects in water treatment. High-efficiency copper ion adsorbing ceramsite, prepared using coal gangue, fly ash, and copper slag as main raw materials, achieves high porosity through optimized proportioning and process conditions, with a maximum copper ion adsorption capacity of 20.6 mg/g, also showing potential for treating other heavy metal wastewater [89]. Porous ceramsite prepared from iron tailings and coal gangue, under the “waste-to-waste” concept, efficiently utilizes resources, demonstrating remarkable lead ion adsorption capacity in acidic conditions (12.28 mg/g), primarily through chemical adsorption, highlighting its advantages in remediating lead-contaminated groundwater [88]. Similarly, lightweight ceramsite produced from fly ash, water treatment sludge, and oyster shells integrates microporous structures with active calcium components, making it suitable as a phosphorus fixation material in artificial wetlands. Dynamic column tests reveal its capability to remove 90% of phosphorus from water, with a theoretical maximum adsorption capacity of 4.51 mg/g [90].
Moreover, the ceramsite maintained high selectivity and recyclability during the adsorption process. In the complex aquatic environment with coexisting ions, competitive adsorption and interference effects occur among different ions. Benefiting from a large surface area and abundant surface-active sites, the ceramsite captures diverse ions via ion exchange, electrostatic interaction, and surface complexation. Studies have shown that the ceramsite exhibits remarkable removal ability for heavy metal ions (e.g., Pb2+, Cd2+, Cu2+, Cr3+, Ni2+), ammonium ions (NH4+), and phosphate ions (H2PO4−, HPO42−). These ions, owing to their higher charge density or stronger interactions with surface functional groups, generally exhibit stronger adsorption affinity than common interfering ions, thus achieving preferential removal.
Meanwhile, the recycling and regeneration performance of ceramsite has also been verified. Effective desorption of captured ions can be achieved through acid, alkali, or saline solution treatments, enabling ceramsite to regain its adsorption capacity. After multiple adsorption–desorption cycles, ceramsite maintains structural stability while still retaining high adsorption efficiency with minimal capacity loss. These findings suggest that coal-based solid waste ceramsite combines ion selectivity with favorable regenerability, offering promising potential for practical water treatment applications.

3.4. Challenges and Improvement Strategies for Large-Scale Application of Coal-Based Solid Waste Ceramsite

Coal-based solid waste ceramsite provides significant advantages by utilizing abundant and low-cost industrial by-products, such as fly ash and coal gangue, thereby promoting resource recycling and reducing dependence on natural clays. During the sintering process, hazardous components are immobilized within stable mineral phases, which minimizes leaching risks and enhances environmental safety. Moreover, its low density, high porosity, and strong adsorption capacity make ceramsite suitable for both construction applications and water treatment, while simultaneously advancing sustainable development goals. While coal-based solid waste ceramsite demonstrates clear environmental and functional advantages, its large-scale application is still restricted by multiple factors. First, the complexity and variability of raw material compositions (e.g., coal gangue, fly ash, and gasification slag) can easily result in unstable product quality, thereby limiting the consistency of material performance. Second, the high-temperature sintering process is highly energy-dependent, leading to elevated production costs and weakening its economic competitiveness.
To overcome the above limitations, improvements can be carried out from multiple aspects. Firstly, by optimizing sintering temperature, flux dosage, and raw material ratios, the mechanical strength and structural stability of ceramsite can be effectively enhanced. Secondly, adopting a composite raw material strategy, such as co-utilizing coal-based solid waste with metallurgical slag, red mud, or clay, can not only improve product performance but also reduce production costs. Third, surface modification and functionalization techniques can potentially strengthen the adsorption efficiency and regeneration performance of ceramsite in water treatment.

4. Conclusions

The recycling of coal-based solid wastes into ceramsite not only provides technical and economic benefits but also directly contributes to several United Nations Sustainable Development Goals (SDGs). In water treatment, ceramsite exhibits excellent performance in the removal of heavy metals, ammonium, and coexisting anions, thereby supporting SDG 6 (Clean Water and Sanitation) through improved water quality and safer wastewater reuse. In the construction sector, replacing natural aggregates with lightweight, durable, and eco-friendly ceramsite promotes SDG 9 (Industry, Innovation and Infrastructure) and SDG 11 (Sustainable Cities and Communities), fostering sustainable building practices. Meanwhile, the valorization of industrial by-products into high-value functional materials aligns with SDG 12 (Responsible Consumption and Production), while reductions in landfilling and emissions further contribute to SDG 13 (Climate Action). Beyond these sustainability benefits, the resource utilization of coal-based solid wastes represents a key pathway for achieving clean and efficient coal usage, significantly mitigating environmental pollution and advancing circular economy practices. Nevertheless, current research faces challenges such as low resource utilization efficiency, high technological costs, and insufficient multi-source collaborative utilization. To overcome these limitations and realize large-scale, high-value applications, future efforts should prioritize: (i) enhancing policy incentive frameworks, advancing industry standardization, and developing systematic, scientific management and evaluation systems; (ii) fostering multi-industry collaborative utilization approaches to integrate coal-based solid waste ceramsite into construction, energy, and environmental fields, thereby optimizing resource efficiency; and (iii) promoting technological innovation to optimize ceramsite preparation processes, reduce costs, and refine functionalization technologies for improved performance in pollution control and ecological restoration. By addressing these aspects, coal-based ceramsite utilization can not only accelerate resource-efficient and environmentally friendly societal development but also advance global sustainability objectives.

Author Contributions

Conceptualization and Writing—original draft preparation, H.W.; Supervision and Writing—review and editing, C.L.; Methodology and Visualization, C.Z.; Methodology, Z.G. All authors have read and agreed to the published version of the manuscript.

Funding

This work received support from the National Natural Science Foundation of China. (No. 52104243), Anhui Engineering Research Center for Coal Clean Processing and Carbon Reduction (CCCE-2023004), Graduate Innovation Funds of Anhui University of Science and Technology (2024cx2087). The authors express their gratitude for the financial support provided by the aforementioned agencies.

Conflicts of Interest

The authors declare no conflicts of interest.

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Figure 1. The productive output and washing rate of raw coal and raw coal for washing in China from 2014 to 2024.
Figure 1. The productive output and washing rate of raw coal and raw coal for washing in China from 2014 to 2024.
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Figure 2. Preparation process of sintered ceramsite (a) and non- sintered ceramsite (b).
Figure 2. Preparation process of sintered ceramsite (a) and non- sintered ceramsite (b).
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Figure 3. Immobilization effect for heavy metals about ceramsite [48].
Figure 3. Immobilization effect for heavy metals about ceramsite [48].
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Figure 4. (a) The evolution mechanism process of ceramsite pore [85]. (b) Microscopic pore structure of ceramsite [86].
Figure 4. (a) The evolution mechanism process of ceramsite pore [85]. (b) Microscopic pore structure of ceramsite [86].
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Figure 5. Adsorption mechanism of ceramsite [87]. (a) Adsorption mechanism of PO43− on ceramsite; (b) adsorption mechanism of H2PO4−, HPO42−, and PO43− on ceramsite.
Figure 5. Adsorption mechanism of ceramsite [87]. (a) Adsorption mechanism of PO43− on ceramsite; (b) adsorption mechanism of H2PO4−, HPO42−, and PO43− on ceramsite.
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Table 1. Utilization modes and features of typical coal-based solid wastes.
Table 1. Utilization modes and features of typical coal-based solid wastes.
Raw MaterialUtilization ModesFeaturesReferences
Coal gangueSubgrade fill materialExhibits good performance, with dynamic stiffness meeting the requirements for subgrade materials.[21,22]
Preparation of molecular sieveAll parameters fully meet the requirements of molecular sieves and exhibit strong adsorption capacity.[23,24]
Concrete coarse aggregateLightweight, environmentally friendly, energy-saving and cost-effective.[25,26]
Coal fly ashPreparation of concreteRefine pore structure, strengthen long-term mechanical properties, and ameliorate creep behavior.[27]
Preparation of glass-ceramicsHigh compressive strength, low heavy metal leaching concentration, and significant improvement in crystallinity.[28,29]
Preparation of aerogelsThe specific surface area and pore volume are relatively large, resulting in good adsorption capacity.[30,31]
Soil conditionerImprove soil physicochemical properties, increase plant biomass, and enhance metal tolerance.[32,33]
Water treatment adsorbent.Effectively removes various water pollutants.[34]
Coal slimeCopper tailings modifierPromotes plant growth and increases the nutrient elements in copper tailings.[35]
Secondary combustion in circulating fluidized bed is adopted.The pollution to the environment is reduced, and the synergistic treatment of organic and inorganic substances in coal slime is realized.[36,37,38]
Coal gasification slagPorous materialPossesses a large specific surface area, high porosity, and strong adsorption capacity.[39]
Environmental remediation materialsImprove soil structure and remediate heavy metal-contaminated soil.[40,41]
Table 2. Chemical compositions of typical coal-based solid waste wt%.
Table 2. Chemical compositions of typical coal-based solid waste wt%.
Types of Coal-Based Solid WasteSourceSiO2Al2O3Fe2O3CaOK2OTiO2MgONa2OCitation
Coal gangueShanxi73.3015.952.601.634.14 1.230.62[50]
Henan60.4425.653.94.582.2 [51]
Liaoning58.8120.668.153.693.311.152.310.68[52]
Jiangsu61.6919.114.162.353.04 0.642.28[53]
Anhui58.2032.003.961.011.741.23 0.34[54]
Coal fly ashGuangxi52.0529.656.593.622.950.921.33 [55]
Hubei46.5434.886.775.040.46 [56]
Guangdong43.3432.195.303.551.011.840.500.26[57]
Anhui54.6032.203.201.500.801.300.600.20[58]
Guizhou46.3420.7413.492.421.63 1.141.74[59]
Coal gasification slagNingxia49.3519.0110.0611.382.201.572.412.15[60]
Shaanxi30.9411.0123.2217.19 0.610.835.58[61]
Shanxi26.3014.542.594.661.030.670.490.91[62]
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Wang, H.; Liu, C.; Zhu, C.; Gong, Z. Resource Recycling and Ceramsite Utilization of Coal-Based Solid Waste: A Review. Minerals 2025, 15, 948. https://doi.org/10.3390/min15090948

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Wang H, Liu C, Zhu C, Gong Z. Resource Recycling and Ceramsite Utilization of Coal-Based Solid Waste: A Review. Minerals. 2025; 15(9):948. https://doi.org/10.3390/min15090948

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Wang, Han, Chunfu Liu, Chenyu Zhu, and Zhipeng Gong. 2025. "Resource Recycling and Ceramsite Utilization of Coal-Based Solid Waste: A Review" Minerals 15, no. 9: 948. https://doi.org/10.3390/min15090948

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Wang, H., Liu, C., Zhu, C., & Gong, Z. (2025). Resource Recycling and Ceramsite Utilization of Coal-Based Solid Waste: A Review. Minerals, 15(9), 948. https://doi.org/10.3390/min15090948

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