Life cycle greenhouse gas emissions of electricity generated from waste coal in the United States

Enabling enterprise coordination without fiscal burden: New policy pathways for coal waste management

Trade-off between quantity and quality: Coal waste particle size regulates composting humification via biotic and abiotic pathways

In this study, a sustainable geopolymer mortar has been developed entirely from industrial waste materials, including coal washing waste (CWW) ash, recycled glass powder (RGP), and calcium carbide residue (CCR), reinforced with polypropylene fibers (PPF). A five-stage experimental approach was employed to optimize the binder composition, alkaline activator ratio (Na2SiO3/NaOH) (NS:NH), alkali solution-to-binder ratio (S:B), fiber content, and the heat-curing process, based on mechanical performance. The optimal binder consisted of 7% CWW ash, 10% RGP, and 20% CCR, activated at an NS:NH ratio of 1.5 and an S:B ratio of 0.65. Incorporation of 0.8% PPF increased flexural strength by approximately 7% compared to the unreinforced geopolymer mortar due to effective crack-bridging and improved matrix integrity. Heat curing at 100°C for 24h resulted in the highest performance, yielding a 28-day compressive strength of 42.15MPa, flexural strength of 5.23MPa, and UPV of 4746m·s⁻¹, representing improvements of 50%, 45.2%, and 10.1%, respectively, over the Portland cement control sample. SEM, FTIR, and XRD analyses confirmed the formation of dense aluminosilicate and calcium-rich gel phases, which correlate with the enhanced mechanical properties. The novelty of this research lies in the synergistic utilization of three industrial wastes, combined with fiber reinforcement and optimized curing, to produce a high-performance, low-carbon geopolymer mortar suitable for both structural and non-structural engineering applications.

ABSTRACT Coal wastes present significant environmental and disposal challenges, primarily due to the extensive scale of mining operations required to meet industrial demands. The primary objective of the study was to assess the technical feasibility of utilizing coal waste through the preparation of fuel agglomerates, so that they can be used in various industrial and domestic applications. In this study, two coal waste samples (CS-1 and CS-2) were utilized for briquette preparation at ambient conditions, using molasses and sodium lignosulfonate as binders. A systematic investigation was conducted to examine the impact of binder type, binder dosage, and drying method on the compressive strength of the briquettes. Binder composition was varied from 0 to 25 wt.%, and the briquettes were dried under atmospheric conditions for 24 hours and in an oven for 2 hours. Compressive strength results showed that oven-dried briquettes had higher compressive strengths compared to air-dried briquettes, with an optimal binder content ranging from 20 to 25 wt.%. High compressive strengths of 279 kg/cm2 and 124 kg/cm2 were obtained for CS-1 briquettes. CS-2 briquettes showed lower strengths of 92.5 kg/cm2 and 74.3 kg/cm2. Optimized briquettes were subjected to spectroscopic and microscopic analysis to understand the inter-particle bonding and structural formations.

Humus-containing organic and organo-mineral fertilizers play a key role in increasing soil fertility due to their high water-holding capacity, improved water permeability, and ability to reduce phosphorus fixation by calcium and magnesium ions in calcareous soils and by sesquioxides in acidic soils. Organic matter from livestock waste, peat, and brown coal can enrich fertilizers with humus. However, plant residues such as aspen bark, agricultural husks, and licorice root meal are among the most effective additives to produce organic fertilizers. The present study evaluates the synthesis of phosphorus-humus fertilizers in grain form using indicator phosphate rocks discovered in the Kyzylkum deposit, Turkmenistan, and oxidized licorice paste, treated with hydrogen peroxide and acetic acid. The methodology lab experiment consisted of three steps. In the first step, the oxidation behavior of finely ground licorice meal (particle size < 0.1 mm) was investigated using an aqueous hydrogen peroxide solution and acetic acid at mass ratios relative to the organic fraction of the licorice meal in the range of H2O2: CH3COOH = 100 : (10–20) : (0.1–1). In the second step, the phosphate rock was decomposed by 92% sulfuric acid, requiring 30-80% equivalent amounts for monocalcium phosphate. In the third step, the resulting products were mixed with the oxidized licorice paste at a ratio of 100:10:1. This paper evaluates the optimal conditions for processing the phosphorus-humus fertilizer, also producing flowcharts for processing, such as phosphate, provided by each resource. The efficiency of this new technology is presented. The results suggest that low rock phosphate and waste licorice root are environmentally friendly and can be recommended as an alternate tool to reduce the use of high-consumption chemical fertilizers or time consuming conventional composting process.

ABSTRACT Disposal of a large volume of coal wastes generated during low-ash coal separation creates an environmental hazard. This urges the need for demineralization of coal wastes, especially the fine fraction. Therefore, demineralization by different physical and chemical methods is being explored by various researchers in order to obtain a clean coal product with significant recovery of carbon values. Furthermore, as feed coal stocks are of metallurgical grade, the demineralized coals can create better micro-structures with stacked carbon layers during the process of carbonization. As a result, demineralized coals are a promising precursor for manufacturing synthetic anode materials for Lithium-ion batteries (LIB). Demineralized coal wastes upon pyrolysis and catalytic pyrolysis deliver excellent reversibility and efficiency in Li-ion batteries. Half-cell tests show an initial discharge capacity of 514 mAh g−1 with a Coulombic efficiency of 81.8% for catalytic pyrolysis products. The cycle efficiency improved with the increase in pyrolysis temperature due to the stacking of carbon layers with optimum interlayer spacing, thereby improving the crystallinity required for Li+ intercalation. The electrochemical performance results clearly show that the metallurgical-grade, demineralized coals are suitable for preparing high-performance anode materials at pyrolysis temperatures (900–1300°C). Full cell tests with lithium iron phosphate as cathode exhibit a specific capacity of 165 mAh g−1, which further demonstrates the suitability of the material for commercial energy storage applications.

ABSTRACT In this study, choline chloride (ChCl) with glycerol (Gly) deep eutectic solvent (ChCl:2Gly) was prepared and used as a solvent for the mixing of lignite coal (LC) and cashew nutshell waste (CNSW) at different molar ratios (1:3, 2:2 and 3:1). The pure LC, CNSW and their blended material in the presence of ChCl:2Gly were characterised using Fourier-transform infra-red (FT-IR) spectroscopy, X-ray diffraction (XRD), thermogravimetric analysis and differential scanning calorimetry (TG-DSC) and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX). Results of the FT-IR spectra confirm that there is a structural change while mixing LC and CNSW in the presence of ChCl:2Gly. Thermal stability and thermal behaviour of blended material at 1:3 and 2:2 are better than 3:1 ratio, which indicates that CNSW and ChCl:2Gly influence their chemical structure changes, high thermal stability, morphology defects and amount of carbon reduction.

Investigation on high temperature co-melting characteristics of municipal solid waste incineration (MSWI) fly ash and coal fly ash: Ash fusibility and flowability

This study assessed the feasibility of cultivating Lavandula dentata in Technosols produced from fine and coarse coal mining waste, focusing on plant development, substrate functionality, essential oil production, and post-mining ecosystem restoration. The Technosols were formulated using coal waste from the Moatize Coal Mine, Mozambique, combined or not in different configurations with agricultural soil and amended with sewage sludge (3% organic matter) and chemical fertilizer to ensure adequate nutrient availability. The experiments were conducted in 30 L containers, performed in triplicate for each experimental group. All settings allowed good plant growth, although the treatment that used only fine waste presented the closest performance to agricultural soil in terms of the production of aerial biomass. In this case, the dried biomass production of the shoots reached an average of 165 g per pot over 8 months (with a standard deviation of 20.3). The study showed a positive correlation between plant development and the available water capacity of the substrates. The plant tissue of L. dentata, in all the Technosols configurations studied, presented a similar composition to the control, with a biomass composition within the standard range established by the literature. The essential oil production ranged from 0.3 to 0.7% (m/m), averaging 0.5% (m/m), with chemical characteristics also alike the control trial. Technosols composed of coal waste from Moatize appear to be an alternative, both to provide a suitable destination for mining waste and to provide conditions for the revegetation and recovery of degraded areas by coal mining. This avoids the commissioning of nearby areas to supply soil for the restoration process. L. dentata, in addition to its various medical, ornamental, and aromatic uses, has potential as an “ecological trigger” in the restoration process with environmental and socioeconomic benefits.

The valorization of industrial solid wastes into construction materials represents an important pathway toward resource efficiency and carbon reduction in the building sector. In this study, sustainable kaolinitic clay-based ceramics were developed using ternary blends of steel slag (SS), coal fly ash (CFA), and recycled waste glass bottle-derived powder (WGBP). The effects of WGBP content and firing temperature on phase evolution, microstructural development, densification behavior, and key physico-mechanical properties were systematically investigated. The results show that at intermediate temperatures (1000–1100 °C), the addition of 5 wt% WGBP promotes liquid-phase sintering, leading to enhanced densification, reduced water absorption, and compressive strengths up to 44 MPa, whereas higher glass contents at elevated temperature induce over-fluxing and pore entrapment, reducing strength despite comparable density. XRD, FTIR, and SEM analyses confirm the progressive vitrification and structural reorganization of the aluminosilicate matrix. The sustainability assessment identifies the 5 wt% WGBP formulation as the most balanced option, combining adequate mechanical performance with lower energy demand and CO2 emissions. Overall, the proposed approach provides a technically viable and resource-efficient route for the integrated utilization of multiple industrial wastes in construction ceramics.

ABSTRACT Technosols are anthropogenic soils, and are mostly intentionally created and/or modified to serve a specific purpose, such as waste management and the restoration of ecosystems degraded by industrial activities. In this sense, open-cast coal mining areas can be classified as Technosols, which already use their own mining waste in their topographic restoration. The construction of Technosols for the purpose of mining waste disposing and recovering degraded areas has the potential to offset up to 60 % of the CO 2 emissions caused by this activity, contributing achieving Sustainable Development Goals (SDGs) 13, 15 and 2 (in some cases, depending on the type of residue to be used in the overburden layer), relating respectively to climate action, the preservation of terrestrial life, and hunger eradication. Therefore, this study aims to provide a literature review of Technosols constructed from coal mining waste, highlighting the challenges that still need to be addressed by soil science to restore these areas ecologically. The methodology consisted of a bibliometric analysis using the terms “Mined Soils” OR “Minesoils” OR “Technosols” AND “Coal” in the Web of Science Core Collection database. The search was restricted to article-type documents published in English between 2004 and 2023, resulting in a dataset of 199 articles. The analysis was performed using VOSviewer and HistCite software, which enable bibliographic coupling between bibliometric variables such as countries, keywords, and citations. The analysis of keyword co-occurrence highlighted a trend towards increased academic relevance of topics related to the environmental contamination potential of coal mining waste, carbon sequestration by Technosols, the morphological characteristics of these soils, and recovery indicators for mined areas. The integration of the properties that characterize soil health, especially the biological ones, is the main gap in this field of study. On a global scale, Technosols are a promising strategy for the recovery of areas degraded by anthropogenic activities, aligning with greater efficiency in waste management and the mitigation of impacts associated with the climate crisis, due to their high potential for CO 2 capture.

The topic of improving the strength and performance properties of secondary polyamide materials as part of their functional modification is a very relevant area of expanding the possibilities of secondary use of plastic waste. The article aims to conduct a systematic study of the combined modification of polyamide waste agglomerate by six different types of carbon materials to improve their technological and strength properties. PA6 waste agglomerate from polyamide clothing items, tights, socks, and various carbon materials were studied: masterbatch for polyamides MW-PA CB10, brown coal humic substances, coke residue from pyrolysis, a mixture of plastic waste, and finely dispersed coal enrichment waste. A sustainable polymer composite based on a modified agglomerate of PA6 waste was obtained by extruding pre-prepared raw materials in a single-screw extruder. The structural and morphological analysis of the studied carbon materials showed that, within the framework of the combined modification of polyamide-6 waste agglomerate, they should perform different functions related to their distinct morphology and chemical composition. Thus, humic substances can act as functional modifiers and compatibilizers due to their nanodispersity and a wide range of active chemical groups. In contrast, coke residue from pyrolysis and coal enrichment waste will act as a functional filler to improve the complex strength properties of sustainable polymer composites. As part of a study on the effect of modifying polyamide-6 waste agglomerate by carbon materials on its complex technological characteristics, it was demonstrated that humic substances enhance sustainable polymer composite’s technological properties by increasing the melting temperature and melt flow index while reducing density. The increase in the functional effect of humic substances is due to the growth of a wide range of active chemical groups (hydroxyl, carboxyl, peptide). During the initial oxidation of brown coal, the coke residue from pyrolysis and coal enrichment waste served as a filler, increasing the sustainable polymer composite’s density and melt flow index. As part of the study of the effect of modification by carbon materials on the complex strength characteristics of polyamide-6 waste agglomerate, it was shown that all carbon materials studied, except for coke residue, improve the strength characteristics of polyamide-6 waste agglomerate. The optimal content of different types of humic substances is 0.5% wt., while the sustainable polymer composite’s impact strength and breaking stress during bending increase with the increase in the functionalization of humic substances during the oxidation of brown coal. It has been shown that the combination of small amounts of oxidized humic substances at the level of 0.5% by weight, as a functional additive with a masterbatch MW-PACB10 in an amount of 2–3.5%wt., provides materials with increased impact strength from 23 to ~48 kJ/m2 and bending fracture stress from 115 to ~135 MPa, which allows returning secondary PA6 waste to the “traditional areas of primary PA6” in the manufacture of general technical parts and products.

A review of strategic metal extraction from coal and coal-based solid waste: Towards green innovation through waste recycling and process integration

Carbon monoxide formation during the co-firing of coal and biomass waste fuels in a 10 kWth bubbling fluidized bed rig under oxy-fuel combustion conditions

Reaction molecular dynamics simulation of pressurized co-pyrolysis of waste plastic and coal: Synergistic mechanism analysis

Circular upcycling of waste PET and coal fly ash into MIL-125(Ti)/zeolite hybrid adsorbents for water treatment and CO2 capture

Intensifying global climate change and continuously increasing CO 2 emissions make the development of efficient, low‐cost CO 2 capture technologies a critical global challenge. Porous carbon materials have emerged as a research hotspot in CO 2 adsorption due to their high specific surface areas, tunable pore structures, and modifiable surface chemistry. In this study, coal tar pitch, anthracite, lignite, and blue‐coke were employed as precursors to prepare and characterize porous carbons via KOH chemical activation and urea‐assisted nitrogen doping, and their CO 2 adsorption performance was investigated. Experimental results demonstrate that the coal‐derived porous carbons exhibit superior structural characteristics, including an ultrahigh specific surface area (up to 3304 m 2 /g), hierarchical pore architecture, and abundant surface functional groups. Nitrogen doping significantly enhanced surface alkalinity and chemical adsorption capacity, achieving a CO 2 adsorption capacity of 162.1 mg/g at 0.3 MPa—a 25% improvement compared to undoped counterparts. Dynamic adsorption tests revealed good cyclic stability, with adsorption capacity recovery rates of 88.5%–96.6% after 30 min N 2 purging and complete regeneration within 60‐min purging. This study demonstrates coal‐based porous carbons’ excellent PSA performance, highlighting their potential as efficient, low‐cost adsorbents for industrial CO 2 capture and CCUS applications.

Design, preparation and application of a novel NaP zeolite-based slow-release fertilizer via resource recovery from coal gangue

Pioneering next-gen 3D-printed ceramic membranes by upcycling waste coal fly ash via solvent-based slurry stereolithography for wastewater treatment