Search Results (52)

Solid fuels are still widely used in household heating in Europe and North America. Emissions from boilers are released in proximity to people. Therefore, there is a need to minimise the toxicity of emissions affecting human health to the greatest extent possible. This study compares the genotoxic potential of the emissions of four boilers of modern and old design (automatic, gasification, down-draft, over-fire) operating at reduced output to simulate the real-life combustion fed by various fossil and renewable solid fuels (hard coal, brown coal, brown coal briquettes, wood pellets, wet and dry spruce). Organic emissions were tested for genotoxic potential by analysing bulky DNA adducts and 8-oxo-dG adduct induction. There was no consistent genotoxic pattern among the fuels used within the boilers. Genotoxicity was strongly correlated with polycyclic aromatic hydrocarbon (PAH) content, and even stronger correlation was observed with particulate matter (PM). In all measured variables (PM, PAHs, genotoxicity), the technology of the boilers was a more important factor in determining the genotoxic potential than the fuels burned. The highest levels of both bulky and 8-oxo-dG DNA adducts were induced by organics originating from the over-fire boiler, while the automatic boiler exhibited genotoxic potential that was ~1000- and 100-fold lower, respectively. Full article

The generation of fine coal particles during mining and processing presents significant environmental and logistical challenges, particularly in coal-dependent, developing countries like South Africa (SA). This review critically evaluates the technical viability of fine coal briquetting as a sustainable waste-to-energy solution within a SA context, while drawing from global best practices and comparative benchmarks. It examines abundant feedstocks that can be used for valorization strategies, including fine coal and agricultural biomass residues. Furthermore, binder types, manufacturing parameters, and quality optimization strategies that influence briquette performance are assessed. The co-densification of fine coal with biomass offers a means to enhance combustion efficiency, reduce dust emissions, and convert low-value waste into a high-calorific, manageable fuel. Attention is also given to briquette testing standards (i.e., South African Bureau of Standards, ASTM International, and International Organization of Standardization) and end-use applications across domestic, industrial, and off-grid settings. Moreover, the review explores socio-economic implications, including rural job creation, energy poverty alleviation, and the potential role of briquetting in SA’s ‘Just Energy Transition’ (JET). This paper uniquely integrates technical analysis with policy relevance, rural energy needs, and practical challenges specific to South Africa, while offering a structured framework for bio-coal briquetting adoption in developing countries. While technical and economic barriers remain, such as binder costs and feedstock variability, the integration of briquetting into circular economy frameworks represents a promising path toward cleaner, decentralized energy and coal waste valorization. Full article

Deep coal seams in the Junggar Basin, China, have demonstrated high gas yields due to enhanced pore structures resulting from hydraulic fracturing. However, raw coal samples inadequately represent these stimulated reservoirs, and acquiring fractured core samples post-stimulation is impractical. To address this, a novel and operable laboratory method has been developed to fabricate porosity-enhanced synthetic coal plugs that better simulate deep coalbed methane reservoirs. The fabrication process involves crushing lignite and separating it into three particle size fractions (<0.25 mm, 0.25–1 mm, and 1–2 mm), followed by mixing with a resin-based binder system (F51 phenolic epoxy resin, 650 polyamide, and tetrahydrofuran). These mixtures are molded into cylindrical plugs (⌀50 mm × 100 mm) and cured. This approach enables tailored control over pore development during briquette formation. Porosity and pore structure were comprehensively assessed using helium porosimetry, mercury intrusion porosimetry (MIP), and micro-computed tomography (micro-CT). MIP and micro-CT confirmed that the synthetic plugs exhibit significantly enhanced porosity compared to raw lignite, with pore sizes and volumes falling within the macropore range. Specifically, porosity reached up to 27.84%, averaging 20.73% and surpassing the typical range for conventional coal briquettes (1.89–18.96%). Additionally, the resin content was found to strongly influence porosity, with optimal levels between 6% and 10% by weight. Visualization improvements in micro-CT imaging were achieved through iodine addition, allowing for more accurate porosity estimations. This method offers a cost-effective and repeatable strategy for creating coal analogs with tunable porosity, providing valuable physical models for investigating flow behaviors in stimulated coal reservoirs. Full article

Deep coalbed methane (CBM) reservoirs have the characteristics of low permeability, low porosity, and low water saturation, which easily experience wellbore instability due to drilling fluid, severely affecting drilling safety. Based on the physical property analysis of coal samples, the wellbore instability mechanism of the deep CBM reservoir was investigated by multiple methods. It was found that the wellbore instability is mainly caused by drilling fluid intrusion and the interaction between drilling fluid and coal formation; the fracture pressure of coal after immersion decreased from 27.4 MPa to 25.0 MPa because of the imbibition of drilling fluid. A novel nano-plugging agent with a size of 460 nm was prepared that can cement coal particles to form disc-shaped briquettes with a tensile strength of 2.27 MPa. Based on that, an effective anti-collapse drilling fluid for deep coal rock reservoirs was constructed, the invasion depth of the optimized drilling fluid was only 6 mm. The CT result shows that the number of fractures and pores in coal rock significantly reduced after treatment with the wellbore-stabilizing drilling fluid; nano-plugging anti-collapse agent in drilling fluid can form a dense layer on the coal surface, and then the hydration swelling of clay in the wellbore region can be effectively suppressed. Finally, the drilling fluid in this work can achieve the purpose of sealing and wettability alternation to prevent the collapse of the wellbore in the deep coal reservoir. Full article

The modern metallurgical industry produces approximately 90% of the volume of all produced steel; for this, integrated technology based on fossil materials such as coal, fluxes, and especially iron ore is used. This industry generates large amounts of waste and by-products at almost all stages of production. Alternative iron and steel production technologies based on iron ore, methane, or pure hydrogen are also not waste-free. To ensure sustainable waste management, efforts are made to seal processes as well as capture and recycle dusty waste. This work presents the results of research on the processing of sludge resulting from the dedusting of the basic oxygen furnace (BOF) process and landfilling in a lagoon. The work discusses the treatment of fine dusty sludge hydrated to 26–60% H₂O, to which various amounts of caking agents were added; also discussed are the rheological characteristics of the tested suspension systems, the possibility of forming these systems into larger fractions, and rapid drying using 100–600 W microwaves with a drying time of 1–9 min. The aim was to identify, describe, and characterize the parameters of the agglomeration process and obtain a product that was durable enough to transport and dose into slag baths in order to reduce iron oxides in liquid phases. During the research, completely dried briquettes with an appropriate strength were obtained. The study demonstrates that microwave drying at 300 W for 6 min achieved complete drying with a weight loss of 35%, whereas a higher-power treatment at 750 W for 2 min enhanced compressive strength by up to 95% and reached 15 N/psc, which was comparable with green iron ore pellets. This approach offers a sustainable alternative to traditional methods, but with a reduced drying time. Full article

Cardiovascular diseases (CVD) are one of the leading causes of death globally, and a major contributor to CVD mortality is ambient air pollution (AAP). This study aimed to evaluate associations between AAP and mortality from CVD, including ischemic heart diseases (IHD) and strokes. Data on daily mortality records, six criteria AAP and meteorology in the capital city of Mongolia were collected between 1 January 2016 and 31 December 2022. A time-stratified case-crossover design was analysed with distributed lag conditional Poisson regression to estimate the relative risk of CVD mortality. We found that for each interquartile range increase in PM_2.5, PM₁₀, SO₂ and NO₂ pollutants, the risk of CVD mortality increased by 1.5% (RR = 1.015; 95% CI: 1.005, 1.025), 4.4% (RR = 1.044; 95% CI: 1.029, 1.059), 3.1% (RR = 1.033; 95% CI: 1.015, 1.047) and 4.8% (RR = 1.048; 95% CI: 1.013, 1.085) at lag01, respectively. The association between all pollutants, except O₃, and CVD mortality was higher in subgroups ≥ 65 years and male, during the cold season and after using a new type of coal briquettes. Despite using the new type of coal briquettes, Ulaanbaatar’s ambient air pollution remained higher than the WHO’s guidelines. Based on our findings, we recommend that efforts should be focused on adopting more efficient strategies to reduce the current pollution level. Full article

The steel industry accounts, according to the International Energy Agency, for ~6.7% of global CO₂ emissions, and the major portion of its contribution is from steelmaking via the blast furnace (BF) route. In the short term, a significant reduction in fossil CO₂ emissions can be achieved through the introduction of bio-coal into the BF as part of cold bonded briquettes, by injection, or as part of coke. The use of bio-coal-containing residue briquettes was previously demonstrated in industrial trials in Sweden, whereas bio-coal injection was only tested on a pilot scale or in one-tuyere tests. Therefore, industrial trials replacing part of the pulverized coal (PC) were conducted. It was concluded that the grinding, conveying, and injection of up to 10% of charcoal (CC) with PC can be safely achieved without negative impacts on PC injection plant or BF operational conditions and without losses of CC with the dust. From a process point of view, higher addition is possible, but it must be verified that grinding and conveying is feasible. Through an experimentally validated computational fluid flow model, it was shown that a high moisture content and the presence of oversized particles delay devolatilization and ignition, lowering the combustion efficiency. By using CC with similar heating value to PC, compositional variations in the injected blend are not critical. Full article

Conducted by the nonprofit organization Breathe Mongolia—Clean Air Coalition, this study investigated ambient air pollution in Ulaanbaatar, focusing on the significant role of coal briquette combustion within ger areas. This combustion not only contributes to outdoor air pollution but also significantly degrades indoor air quality within these traditional dwellings, leading to substantial health concerns. To address this challenge, the study assessed indoor air pollution in gers—traditional Mongolian yurts—that had implemented Cooking, Heating, and Insulation Packages (CHIP), a program offering subsidized electrical heating, cooking, and insulation materials. The study encompassed 28 gers, among which 25 were equipped with CHIP while 3 were not, enabling a comparative analysis. Employing cost-effective technology, carbon monoxide levels were monitored across all 28 gers using Binary System monitors. Fine particulate matter concentrations were measured using AirVisual monitors in 14 of these gers. Data collection occurred during the winter of 2022–2023. To comprehensively assess indoor air quality within gers and ascertain the efficacy of interventions like CHIP in diminishing indoor air pollution, Breathe Mongolia intends to continue monitoring efforts within ger areas. These initiatives strive to address data gaps and inform strategies aimed at enhancing indoor air quality. Full article

In energy scarcity, particularly in Agri-based developing economies, bio-coal briquetting is the most suitable means of meeting sustainable energy needs utilizing agricultural waste. In this study, briquettes were made from an indigenously designed briquetting machine for investigating coal–biomass proportion blend using coal from Dara Adam Khel, Khyber Pakhtunkhwa in Pakistan, and pomegranate/olive waste to analyze their resulting calorific value, strength, and geochemical properties. A central composite design (CCD) and response surface methodology (RSM) were employed to design the experiments and analyze the data. Regression models were developed for each biomass type, demonstrating their adequacy and reliability for further analysis and prediction. Energy Dispersive X-ray Spectroscopy (EDX) analysis provided insights into the elemental composition of the coal briquettes. Mechanical analysis was performed to assess the strength of the briquettes, with varying compositions showing different levels of strength. Optimization using a composite desirability function yielded an optimal calorific value of 6728 kJ/kg. In summary, this study underscores the viability of bio-coal briquetting as a transformative solution to alleviate energy scarcity. Repurposing agricultural waste curtails resource depletion while mitigating waste disposal challenges. The optimized calorific value aligns with eco-friendly energy initiatives, advancing a greener path toward energy security. Full article

Fuel types are essential for the control systems of briquette biofuel boilers, as the optimal combustion condition varies with fuel type. Moreover, the use of coal in biomass boilers is illegal in China, and the detection of coals will, in time, provide effective information for environmental supervision. This study established a briquette biofuel identification method based on the object detection of fuel images, including straw pellets, straw blocks, wood pellets, wood blocks, and coal. The YoloX-S model was used as the baseline network, and the proposed model in this study improved the detection performance by adding the self-attention mechanism module. The improved YoloX-S model showed better accuracy than the Yolo-L, YoloX-S, Yolov5, Yolov7, and Yolov8 models. The experimental results regarding fuel identification show that the improved model can effectively distinguish biomass fuel from coal and overcome false and missed detections found in the recognition of straw pellets and wood pellets by the original YoloX model. However, the interference of the complex background can greatly reduce the confidence of the object detection method using the improved YoloX-S model. Full article

In deep mining, “critical static stress + slight disturbance” is an important inducing form of coal mine rockburst disasters. In previous studies, the critical static stress has been shown to be consistent with the loading direction of a slight disturbance but cannot reflect all types of rockbursts. In addition, the research that uses microseismic (MS) signals to reflect the overall process and critical stages of coal failure and instability under weak-energy and low-frequency disturbance conditions is immature, and more information, such as the critical state, has not been fully revealed. The aims of this paper are to further elucidate the important role of weak-energy and low-frequency disturbances in the occurrence of rockburst disasters. First, briquette samples were prepared from the Tashan Coal Mine, which is severely affected by rockbursts, and their homogeneity was verified using ultrasonic longitudinal wave velocity. Second, the natural frequency of the coal sample specimens was measured using a testing system. Then, based on the self-developed static pressure loading system, dynamic and static combined loading test system and MS signal monitoring device, the MS signal characteristics during the process of coal body failure and instability were comprehensively analysed. Finally, a comparison was made between weak-energy and low-frequency disturbances and impact disturbances. The results are summarized as follows. (1) The longitudinal wave velocity test results reflect that the briquette samples prepared in the experiment have high homogeneity. The smaller the particle size is, the higher the density and moulding pressure, and the denser the sample. (2) The natural frequency of the briquette samples is between 30.79 Hz and 43.34 Hz, and most of them fluctuate at approximately 35 Hz. (3) During the static loading stage, the occurrence of more than three MS signals of larger magnitude in a continuous cluster is an important criterion for the critical failure of the samples. (4) The weak-energy and low-frequency disturbance actually leads to fatigue damage, and the briquette sample experiences three stages: the near-threshold stage, the high-speed expansion stage and the final fracture stage. The smaller the particle size of the coal sample, the denser the specimen, the stronger the amplitude and energy of the single effective MS signal formed during the destruction process, the longer the time duration of crack expansion from the near-threshold stage to the high-speed expansion stage, and the stronger the ability of the coal sample to resist weak-energy and low-frequency disturbances. This study may contribute to a more comprehensive understanding of the destabilization mechanism of coal bodies and MS signal characteristics under weak-energy and low-frequency disturbances and provide a reference for further research and discussion. Full article

Biomass burning is an important source of brown carbon (BrC) which poses high-risk threats to human health and the environment. In this study, bio-coal briquette (coal mixed with biomass), a promising solid fuel for residential combustion, is proven to be a clean fuel which can effectively reduce BrC emission. First of all, an orthogonal experiment with three factors and three levels on the physical property of bio-briquette was carried out to identify the optimal preparation conditions including the ratio of biomass to anthracite, particle size and molding pressure. Then a combustion experiment of the bio-coal briquetted was implemented in a simulated residential combustion system. BrC emission factors (EFs) were calculated based on the detected black carbon (BC) concentration by an aethalometer, and other optical characteristics for organic components of extract samplers, such as mass absorption efficiency (MAE) and absorption angstrom index (AAE), were also explored. Lastly, composition analysis of BrC by a gas chromatography (GC) tandem mass spectrometer (MS) and direct visible images by scanning electron microscopy (SEM) were investigated to provide more detail information on BrC EFs and property change. It was shown that bio-coal briquette had such low BrC EFs that 70–81% BrC was reduced in comparison with an interpolation value of 100% biomass and 100% coal. Furthermore, the composition of BrC from bio-coal briquette burning was different, which consisted of more substances with strong wavelength dependence. Consequently, although MAE declined by 60% at a 540 nm wavelength, the AAE value of bio-coal briquette only decreased slightly compared with interpolation values. To be more specific, tar balls, the main existing form of BrC, were distributed much more sparsely in the SEM image of bio-coal briquette. To sum up, a positive reduction effect on BrC was discovered in bio-coal briquette. It is evident that bio-coal briquette can serve as an alternative solid fuel for residential combustion, which is beneficial for both human health and the atmosphere. Full article

Nigeria has the potential to generate 12,522 MW of electricity, but can only dispatch 4000 MW, which is insufficient for a population of over 200 million people as of 2022. Therefore, Nigerians use solid fuels including firewood and charcoal as an alternative to insufficient electricity for domestic use. The consumption of firewood and charcoal in Nigeria is estimated at 23,745,458 tons and 4,828,689 tons, respectively in 2021, by far the most consumed domestic solid fuel sources in Nigeria. Although there are domestic solid fuel alternatives, such as dung, agricultural residues and coal, to firewood and wood charcoal, their sustainable adoption has been slow in Nigeria, indicating that there is insufficient knowledge of domestic solid fuel sources. This requires a review focused on assessing Nigeria’s national sources of solid fuels. This article presents an overview of the sources of domestic solid fuels in Nigeria, an exploration of different types of firewood and charcoal studies, the impact of solid fuels on climate change and the environment, health risks associated with solid fuel and biomass briquettes and pellets as domestic solid fuel alternatives to charcoal and firewood. The continued production and use of firewood and wood charcoal as domestic solid fuel sources encourage deforestation, desertification and greenhouse gas emission, which in turn pose a threat to a sustainable environment and good health. It is necessary to limit the felling of trees for firewood and charcoal production to curtail their negative impacts on the health of users and the environment. This review covered the thermal, mechanical and physical properties of briquette and pellet fuels as substitutions for firewood and charcoal. It was shown that employing briquettes and pellets as a source of solid fuel in the home will lessen the negative impacts that these fuels have on users’ health, the climate and the environment. Full article

Rock bursts and coal and gas outbursts are geodynamic disasters in underground coal mines. Laboratory testing of raw coal samples is the dominant research method for disaster prediction. However, the reliability of the experimental data is low due to the inconsistency of the mechanical properties of raw coal materials. The utilization of structural coal resources and the development of new coal-like materials are of significance for geodynamic disaster prediction and prevention. This paper studies the failure characteristics and dynamic disaster propensities of coal-like burst-prone briquettes under different gas pressures. A self-made multi-function rock–gas coupling experimental device was developed and burst-prone briquettes were synthesized, which greatly improved the efficiency and precision of the experimental data. The results showed that the burst proneness of the briquette was thoroughly reduced at a critical gas pressure of 0.4 MPa. When the gas pressure was close to 0.8 MPa, both the bearing capacity and the stored burst energy reduced significantly and the dynamic failure duration extended considerably, indicating the typical plastic-flow failure characteristics of coal and gas outbursts. The acoustic emission monitoring results showed that with the increase in gas pressure, the post-peak ringing and the AE energy ratio of coal samples increased, suggesting that the macroscopic damage pattern changed from bursting-ejecting of large pieces to stripping–shedding of small fragments adhered to mylonitic coal. In addition, the transformation and coexistence of coal failure modes were discussed from the perspectives of coal geology and gas migration. This study provides a new method for the scientific research of compound dynamic disaster prevention in burst coal mines with high gas contents. Full article

One of the options for reducing harmful emissions in the production of heat energy is the use of biomass, including in combination with industrial waste (for instance, coal and coke dust). Recent studies demonstrate that a mix of biomass and coal makes it possible to obtain a bio-coal briquette with better characteristics, which is a motivating factor in the search for alternative sources of heat energy from local agricultural waste. The aim of this research is to study the properties of bio-coal briquettes from biomass (sunflower husks and leaves) and industrial waste (coal and coke dust). The raw material was grinded and used for the production of bio-coal briquettes of 20%, 30%, 40%, 50%, 60%, and 70% of biomass. The biomass was grinded to the size of no more than 2 mm for the fine fraction and no more than 6 mm for the coarse fraction. The briquettes were made mechanically using a hydraulic press with a compression pressure of 25 MPa without the use of any binder. The characteristics of the investigated bio-coal briquettes, such as density, strength, moisture content, ash content, volatile yield, calorific value, ignition time, burning duration, and burning rate, have good enough values. The fine fraction briquettes compared to the coarse fraction briquettes have a longer burning time (about threefold longer) and a lower burning rate. For all briquettes, an increase in the composition of coal dust results in a rise in the burning time, whereas the burning rate falls. The best in terms of strength, calorific value and combustion parameters are the following briquettes: 70% sunflower husk and 30% coal dust from the Karazhyra deposit; 60% sunflower husk and 40% coal dust from the Shubarkul deposit; briquettes from 70% sunflower husk and 30% coke dust; briquettes from 80% leaves and 20% coal dust from the Karazhyra deposit; and briquettes from 70% leaves and 30% coal dust from the Shubarkul deposit. The selected briquettes are suitable as an alternative source of fuel. Full article