Flammable Gas Release Research Articles

Low Volume Gas-Flow Seeding For Highly Resolved Velocimetry Of The Boundary Layer

Ensuring fire safety in polymeric materials, which are inherently flammable but widely used in various industries, is of significant societal and economic importance. This study is part of a broader effort to understand polymer combustion and flame retardant effectiveness at a fundamental level. A major focus is the behavior of polymers burning along a vertical wall, a configuration chosen to study the release of flammable gases during pyrolysis, which contributes to the self-sustaining combustion reaction of a fire. This process occurs predominantly near the polymer surface within the boundary layer, requiring detailed analysis to evaluate flame retardant effectiveness. Our experimental setup replicates polymer pyrolysis using a flame-wall interaction burner with a vertical jet and a small inlet to mimic the release of flammable gases. The primary challenge in this setup is the introduction of seeding particles for Particle Image Velocimetry (PIV) measurements at low volume flow rates, which is complicated by reflections from the wall and the small flow scale relative to the main flow. To address this problem, we have developed a novel piezo-based ultrasonic seeder capable of controlled seeding at extremely low flow rates, thereby improving the accuracy of PIV measurements in non-reactive configurations. This seeder uses a piezo ring to excite a perforated metal membrane, forming uniform aerosol droplets. The design ensures a steady supply of particles, which is critical for evaluating boundary layer conditions. Our results demonstrate the seeder’s ability to maintain sufficient seeding density in the low volume flow region, facilitating detailed velocimetry analysis. The innovative seeder design proves effective in overcoming the limitations of conventional methods and provides new insights into polymer combustion processes and the role of flame retardants.

Modeling and Simulation of a Gas-Exhaust Design for Battery Thermal Runaway Propagation in a LiFePO4 Module

The release of flammable gases during battery thermal runaway poses a risk of combustion and explosion, endangering personnel safety. The convective and diffusive properties of the gas make it challenging to accurately measure gas state, complicating the assessment of the battery pack exhaust design. In this paper, a thermal resistance network model is established, which is used to calculate the battery thermal runaway propagation. Gas accumulation after thermal runaway venting of a LiFeO4 module is studied using ANSYS Fluent under different venting schemes. The results show that the scheme of battery inversion and simultaneous exhaust from the side and bottom of the module is optimal. The methods and results presented can guide the design of LiFeO4 cell pack runners.

Experimental investigation on the behavior of thermal super insulation materials for cryogenic storage tanks in fire incidents

The number of vehicles using or transporting cryogenic fuels such as Liquefied Hydrogen (LH2) or Liquefied Natural Gas (LNG) increases fast in the land transportation sector. Does this also entail new risks? The storage of cryogenic fuels requires tanks with Thermal Super Insulations (TSI) to keep the fluid cold and limit the formation of boil-off gas. TSI has proven itself in some applications since the middle of the 20th century, but in the land transport sector they are still quite new, where accidents involving fires, collisions, and their combination are to be expected. This work focuses on investigating the behavior of different types of TSI while exposed to a heat source representing a fire. To this aim, a High-Temperature Thermal Vacuum Chamber (HTTVC) was applied, which allows the thermal loading of a thermal insulation material in a vacuum and measuring the heat flow transported through the TSI in parallel. In this study, the results of 6 samples are presented regarding 3 types of MLI, rock wool, perlites, and microspheres. The thermal exposure caused different effects on the samples. In practice, this can be connected to the rapid release of flammable gases as well as to a Boiling Liquid Expanding Vapour Explosion (BLEVE). These results are relevant for reducing the risks to people and infrastructures in the progressive establishment of tanks for cryogenic fluids in our industry and society. The data presented in the study can be used to improve the design of tanks and TSIs, the assessment of accident scenarios, and the development of measures for first responders.

A honeycomb-inspired carboxymethyl chitosan-covalently link NH2-black phosphorene biobased cellulose green nanocomposites with tremendously enhancement fire safety and thermal conductivity

Biobased carboxymethyl chitosan-modified black phosphorene (BP-CMC) was prepared through an amidation reaction between amino group functionalized black phosphorene (NH2-BP) and CMC. Density functional theory (DTF) express that the adsorption energy between urea and phosphene is −6.28 eV, indicating a strong interaction. The resulting BP-CMC was further applied to reinforce the mechanical, flame-retardant and thermal conductivity performance of honeycomb cellulose nanofiber (CNF) film via vacuum filtration. Cone calorimetry test (CCT) result exhibits that the introduction of 30 wt% BP-CMC significantly promoted the fire safety of CNF. For instance, a 98.41% reduction in smoke production rate (SPR), 92.00 % decline in CO release and a 61.31% decrease in heat release rate (HRR) were observed compared to neat CNF. Furthermore, Thermogravimetric infrared (TG-IR) indicates a significant decrease in the release of flammable gases. Raman spectra verify that the incorporation of 30 wt% BP-CMC improves the graphitization degree of residual chars, thus limiting the transfer of heat and oxygen. The improvement in fire safety is attributed to the formation of an intumescent flame-retardant system, which is rich in carbon source (CMC), acid source (BP) and gas source (amino). Simultaneously, the introduction of 30 wt% BP-CMC into CNF leads to considerable enhancement in thermal conductivity (up to 17.49 %), thermal diffusion (utmost to 43.45 %) and heat capacity (increased by 19.23 %). Moreover, the 30 wt % addition of BP-CMC into CNF possesses excellent mechanical properties with the improvement of toughness (increased by 143.50 %) and tensile strength (increased by 140.90 %). This strategy not only provides a new strategy for functionalizing BP but also upgrades the application potential of BP nanosheets in the fire safety of polymer composite films.

Investigation of urban natural gas pipeline leak and resulting dispersion in a semi-closed space: A case of accident in Shiyan, China

Pipeline is the most common way for delivering natural gas to the urban areas. Nevertheless, pipeline leak accidents can pose significant threats to human life and property safety. This paper investigates the characteristics of urban natural gas pipeline leaks and the resulting gas dispersion in a semi-closed space using a 3D Computational Fluid Dynamics (CFD) model. The characteristics of a pipeline leak is examined considering the impact of shape, dimensions, and location of the aperture. The migration of natural gas in a semi-closed space is tracked, considering the impact of leak location and orientation. To illustrate the model, a real-life case study is conducted to simulate flammable gas release and dispersion resulting from an urban natural gas pipeline leak. The outcome can guide the monitoring and mitigating the consequences of urban natural gas pipeline leaks.

Uncertain lithium-ion cathode kinetic decomposition modeling via Bayesian chemical reaction neural networks

Lithium-ion batteries are the focus of significant recent research interest due to their use in energy storage systems, electric vehicles, and other green technologies. Under various abuse conditions, these batteries undergo thermal runaway, which can lead to rapid temperature rise, flammable gas release, and fires. Current simulation approaches for thermal runaway at the full-cell scale involve utilizing kinetic models fit to experimental data from individual battery components. Despite substantial experimental uncertainty in the literature for these component experiments, prevalent models have not accounted for such uncertainty or noise. Here, we introduce uncertainty quantification for lithium-ion battery cathode thermal decomposition modeling via a novel Bayesian inference methodology. This approach leverages Chemical Reaction Neural Networks and particle-based uncertainty quantification to infer uncertain kinetic parameters while eliminating traditionally used simplifications, allowing for improvements to model accuracy and broader consideration of correlated parameters. We validated this new framework by learning an uncertain decomposition model for NCM333 (nickel-cobalt-manganese) cathode materials using differential scanning calorimetry (DSC) measurements with added synthetic noise. Then, we quantified the uncertainty in NCM811 cathode thermal runaway chemistry using experimental DSC measurements from various sources in the literature. Our methodology’s ability to account for correlated Arrhenius parameters led to much broader uncertain parameter ranges and thus more generalizability at higher temperatures. We additionally found that the NCM811 model distribution learned directly from experimental data in the literature has 4σ onset temperature ranges up to 20 °C wide and specific reaction enthalpy ranges accounting for upwards of 80% of the mean value, carrying significant implications for downstream applications. Our work bridges the gap between noisy or uncertain experimental data and practical cell-scale simulations, thereby facilitating more realistic and robust thermal runaway models that support enhanced battery safety and performance optimization.

Risk area classification for flammable gas dispersion in natural gas distribution station

The accidental release of hazardous gases can pose a significant threat to the operational safety of natural gas distribution stations (NGDS). This paper presents a methodology for classifying risk areas associated with the dispersion of flammable gases in NGDS, utilizing Computational Fluid Dynamics (CFD) simulations. Initially, a comprehensive set of scenarios for flammable gas release in NGDS is established, considering various parameters of the leak source and the wind field. The probabilities of different scenarios are estimated based on the probability of a leak occurring and the frequency of the wind field. Subsequently, a CFD model is developed to simulate the dispersion of flammable gas released within NGDS, enabling the prediction of the distribution area of the released gas. Finally, the risk areas within NGDS are classified by combining the dispersion area of the flammable gas and the probability of each leak scenario. In the case study, the area in NGDS can be classified into four levels based on the risk grades. Natural gas metering skid and natural gas pressure regulating skid module can reach level 4. The risk level in other areas ranges from levels 2 to 3. The results of risk area classification can guide the layout of combustible gas detector. It can also support emergency planning for flammable gas release incidents in NGDS.

Synthesis and performance study of sulfur-containing amino acid ammonium phosphate type flame retardants for cotton fabric

In order to obtain cotton fabrics with high efficiency flame retardance, a new ammonium phosphate type active flame retardant N, N -bis (ammonium phosphate) cysteine (NP-BG), which is nonleaching, covalent attached, durable, functional flame retardants, was synthesized by Mannich reaction and applied to the flame-retardant modification of cotton fabrics. Test results such as FTIR and XPS showed that cotton fabrics had been successfully grafted with NP-BG. The LOI of cotton fabrics treated with 30 % flame retardant was as high as 40.2 %, and after 50 washes, the LOI of cotton fabric was still as high as 28.8 %; demonstrating the durability of flame retardance. The thermogravimetric-infrared coupling (TG-FTIR) test results showed that the flame retardant could change the thermal decomposition pathway of cotton fabric and produce a large amount of residual carbon, thus reducing the decomposition of cotton fiber and the release of flammable gas. In addition, cone calorimetry (CONE) experiments showed that the total heat release (THR) and heat release rate (HRR) of cotton fabrics were significantly reduced after the flame-retardant treatment. These findings indicate that NP-BG is a new flame-retardant material with good application prospects.

Accommodating physical reaction schemes in DSC cathode thermal stability analysis using chemical reaction neural networks

With the increasing demand for applications in vehicles and energy storage systems, lithium-ion batteries have attracted extensive research interest. Thermal runaway in these batteries, which can lead to rapid temperature rise, flammable gas release, and even fires, directly imposes safety concerns. Previous studies have utilized differential scanning calorimetry (DSC) to infer thermal kinetic mechanisms for individual battery components. However, the commonly used Kissinger analysis involves oversimplified assumptions which lead to erroneous quantification of the kinetic parameters and inaccurate physical interpretation of the results. Here, we propose an extension of the recently developed Chemical Reaction Neural Network (CRNN) framework that is not limited by the simplifications from traditional optimization methods and can learn complex, multi-step thermal kinetics from DSC data. After a proof of concept, we leverage this novel approach to improve recent thermal decomposition models for nickel–cobalt–manganese oxide (NCM) cathodes. Its generality and enhanced learning capability enable improved models with better agreement to the data that account for the actual physical coupling between multi-step reaction pathways. The successful development of the CRNN approach to learn such thermal kinetic models from simple DSC data demonstrates its potential to advance thermal runaway modelling for lithium-ion batteries and other complex kinetic systems.

A dynamic approach to identify hazardous areas for H2S-containing natural gas release and explosion accidents on offshore platforms

Many efforts have been made to predict and mitigate the toxic impact and explosion impact. However, they are inadequate for the chain accident of toxic gas-containing flammable gas release and explosion since these two hazardous impacts can happen continuously. Accordingly, an integrated approach concerning chain accident consequence assessment is proposed, in which the human behavior is taken into account. The risk-based concept and grid-based concept are introduced in this approach to integrate the adverse impacts. The approach is applied to a hypothetical chain accident involving H2S-containing natural gas release and explosion on an offshore platform. The emergency evacuation is considered by establishing an emergency evacuation time model. A cumulative H2S inhalation dose along each evacuation trajectory is derived to evaluate the toxic impact by considering the temporal-spatial variation of both H2S profile and sufferers’ positions. The maximum explosion overpressures in the real-time position of the sufferers are extracted to predict the explosion impact. The proposed approach is systematic and efficient for practical engineering applications. It can help to develop safety measures and improve the contingency plan.

Fabrication of halogen-free and phosphorus-free flame retardant and antistatic PAN fibers based on tea polyphenol phenolic resin chelated with iron (Ⅲ) ions

Polyacrylonitrile (PAN) fibers are one of the three major synthetic fibers in the world, but the drawbacks of flammable and static charge accumulation limit their application. To address the issue, tea polyphenol phenolic resin (TPPR) was firstly prepared from biomass tea polyphenol in this paper. Next, TPPR was blended with PAN spinning solution and wet-spun with Fe3+ solution as coagulation bath to construct phosphorus-free and halogen-free flame retardant PAN fibers (TPPR@Fe/PAN). The results indicated that the limiting oxygen index (LOI) value increased from (17.3 ± 0.51)% of PAN fibers to (31.6 ± 0.51)% of TPPR@Fe/PAN. Even after 30 laundering cycles (LCs), the LOI value of TPPR@Fe/PAN was still up to (27.7 ± 0.51)%, indicating good washing durability. Additionally, the heat release capacity (HRC) and total heat release (THR) of TPPR@Fe/PAN had 35.0% and 48.6% reduction, respectively. Furthermore, TPPR@Fe/PAN obtained excellent antistatic ability. Besides, the TG-IR results demonstrated that both the release of flammable and toxic gases were significantly suppressed. In the work, a simple and feasible flame retardant and antistatic strategy was established which was convenient for fabrication of functional PAN fibers on a large scale.

CFD simulations of instantaneously released liquefied gas in urban areas: A case study of LPG tank truck accident in Wenling, China

The accidental release and ignition of flammable liquefied gas can cause catastrophic events, such as flash fires, vapor cloud explosions, and boiling liquid expanding vapor explosion, which severely endanger urban residents and the environment. In the current study, a method for simulating liquefied gas instantaneous release accidents was established to explore the vapor cloud diffusion behavior in urban areas. The rare liquefied petroleum gas instantaneous release accident in Wenling, China is considered as a test case. To this end, an instantaneous release source model that considers the gas phase, liquid pool, and droplets was developed. The CFD model was validated using the damage distribution at the accident site. The simulation results revealed that droplets in the release source, terrains, and large obstacles significantly affected the dispersion behavior and extension distance of the vapor cloud. The evaporation of droplets resulted in a mushroom-shaped cloud. In addition, when the cloud was ignited, the area covered by the LFL was 1.94 and 2.07 times larger in the cases with droplets than those without. The method developed in this study is applicable to developing hazardous chemical transportation and emergency response measures in urban environments to maintain the sustainable cities development.

Al2O3/ZnO composite-based sensors for battery safety applications: An experimental and theoretical investigation

Lithium-ion batteries are vital in one of the key nanotechnologies required for the transition to a carbon-free society. As such, they are under constant investigation to improve their performance in terms of energy and power densities. At the same time, safety monitoring is crucial, as defects in the battery cell can lead to serious safety risks such as fires and explosions as a result of the enormous heat generated in the electrolyte, causing the release of toxic and flammable gases in the so-called thermal runaway. Therefore, early and rapid detection of the gases that form before thermal runaway is of particular interest. To this end, solid-state sensors based on new heterostructured materials have gained interest owing to their high stability and versatility when used in the harsh battery environment. In this work, heterostructures based on semiconductor oxides are employed as sensors for typical components of battery electrolytes and their decomposition products. The sensors showed a significant response to vapors produced by battery solvents or degassing products, making them perfect candidates for the development of successful new prototypes for safety monitoring. Here, we have used a simple and versatile method to fabricate the Al2O3/ZnO heterostructure, consisting of atomic layer deposition (ALD) and thermal annealing steps. These Al2O3/ZnO heterostructures have shown a response to the vapours of 1,3-dioxolane (DOL, C3H6O2), 1,2-dimethoxyethane (DME, C4H10O2), LiPF6, ethylene carbonate (EC) and dimethyl carbonate (DMC), which are typically used as components of the electrolytes in LIBs. The sensors showed a significant response to vapors produced by battery solvents or degassing products, significantly increasing the chances of developing new successful prototypes for safety monitoring. Density functional theory (DFT) calculations were employed to systematically compare the surface reactivity of the α-Al2O3(0001) and the ZnO101̅0 facets, as well as the Al2O3/ZnO101̅0 interface, towards C3H6O2, C4H10O2, nitrogen dioxide (NO2) and phosphorous pentafluoride (PF5), in addition to H2O to assess the impact of relative humidity on the performance of the gas detector. The scanning tunnelling microscopy (STM) images and molecular binding energies compare well with our experiments. The energies of molecular adsorption at the heterostructure suggest that humidity will not affect the detection of the volatile organic compounds. The results presented here show that the potential to detect vapors of the components used in the electrolytes of LIBs, combined with the size control provided by the synthesis method, makes these heterostructures extremely attractive in devices to monitor battery safety.

Interfacial silicon‑nitrogen aerogel raise flame retardancy of bamboo fiber reinforced polylactic acid composites

A triazine derivative containing nitrogen and silicon (SiN) was synthesized and the SiN hybrid aerogel was covered on the surface of bamboo fiber (BF). The modified BF was identified as MBF. The MBF and ammonium polyphosphate (APP) were used to regulate the flame retardancy and mechanical properties of polylactic acid (PLA). The PLA/BF composites were investigated using limiting oxygen index (LOI), UL-94 vertical combustion, cone calorimetry, thermogravimetric analysis linked with infrared spectra (TG-IR) etc. The char residue of MBF at 800 °C is as high as 43.5 % which is 200 % more than that of BF. Incorporating 9 wt% APP generates a PLA9 which displays the UL-94 V2 rating and a LOI value of 28.0 vol%. PLA9/MBF composites display the UL-94 V0 rating and increased LOI values while PLA9/BF composites obtain the UL-94 V2 rating and decreased LOI. The MBF reduces the release of flammable gases during combustion, enhances charring ability and decreases the thermal conductivity of composites. Besides, the tensile and impact strength of PLA9/20MBF is 20 % and 37 % more than that of PLA9/20BF due to stronger interfacial adhesion. This work provides a good method to regulate the flame retardancy and mechanical properties of PLA/BF composites.

Nanostructured multifunctional wood hybrids fabricated via in situ mineralization of zinc borate in hierarchical wood structures

Developing feasible and eco-friendly methods to fabricate multifunctional wood remains an imperative yet challenging task. Prompted by biomineralization, this study proposes the fabrication of nanostructured wood hybrids with efficient flame retardancy, smoke suppression, mold resistance, and antitermite activity via in situ mineralization of nanosized zinc borate (ZnB) particles in a hierarchical void system of wood. ZnB was successfully deposited in the hierarchical nano/microporous cell wall structures, as confirmed by X-ray microtomography and energy-dispersive X-ray spectroscopy. The mineralized wood exhibited excellent heat insulation performance during combustion. The limiting oxygen index of the mineralized wood with 22.1 wt% ZnB (MW22) increased from 22.6% of the untreated wood to 41.2%. Cone calorimetry testing revealed reductions of 51.4%, 89.0%, and 79.5% in average CO yields, total smoke production, and maximum smoke production ratio, respectively, in MW22 relative to those in the untreated wood; the peak heat release rate and total heat release also decreased by 46.9% and 47.9%, respectively. A noncombustible film of molten ZnB covered and cross-linked the carbonaceous char layer, forming a cohesive and robust 3D residual skeleton, which endowed thermal insulation to the wood, delayed oxygen diffusion, reduced flammable gas release, and suppressed toxic smoke. Antitermite tests showed a mothproofing rating of 10 for MW22, far higher than the rating of 4 for untreated wood. Moreover, MW22 exhibited exceptional mold resistance, with an average infection of 0 and an average protective efficiency of 100%. Therefore, in situ mineralization of the wood cell wall architecture with ZnB provides a facile and feasible strategy to fabricate multifunctional integrated wood, which is suitable for scaling up and can be potentially used in modern green buildings.

Comprehensive gas analysis of a 21700 Li(Ni0.8Co0.1Mn0.1O2) cell using mass spectrometry

The failure of lithium-ion batteries (LIBs) can be partly defined by the release of toxic and flammable gases. The composition and volume of these gases varies depending on cell type, failure mechanism, state of charge (SoC) and environmental oxygen (O2) levels. Understanding this relationship and the species produced is essential for battery pack manufacturers relying on real-time monitoring to assess the state-of-health (SoH) of a LIB. It also has ramifications for emergency responders attending thermal runaway (TR) events. In this work, NMC-811 21700 cells were overheated, and the resulting gas analysed in real-time using mass spectrometry (MS). Repeat tests were conducted to account for variability. Work has been carried out to both quantify the volume of gas produced and investigate how gas composition changes during different stages of cell failure. Tests were conducted at 5–100% SoC. Results showed that during safety venting (SV), the major constituent gas is methane (CH4), which was positively correlated with SoC. In contrast, during TR the gas mixture contains hydrogen (H2), carbon dioxide (CO2) and carbon monoxide (CO). Further analysis to quantify gas volumes show a 3 to 5-fold increase, in both air and nitrogen (N2) atmospheres, when SoC is increased from 25% to 100%.

Life-Related Hazards of Materials Applied to Mg–S Batteries

Nowadays, rechargeable batteries utilizing an S cathode together with an Mg anode are under substantial interest and development. The review is made from the point of view of materials engaged during the development of the Mg–S batteries, their sulfur cathodes, magnesium anodes, electrolyte systems, current collectors, and separators. Simultaneously, various hazards related to the use of such materials are discussed. It was found that the most numerous groups of hazards are posed by the material groups of cathodes and electrolytes. Such hazards vary widely in type and degree of danger and are related to human bodies, aquatic life, flammability of materials, or the release of flammable or toxic gases by the latter.

Construction phosphorus/nitrogen-containing flame-retardant and hydrophobic coating toward cotton fabric via layer-by-layer assembly

Excellent flame-retardant cotton fabric with desired hydrophobic is of particular interests for both academia and industry. Herein, an effective multilayer coating consisting of phosphorylated polyethyleneimine (P-PEI) and hydrophobic modified ammonium polyphosphate (MAPP) was successfully constructed on cotton fabric through a facile layer-by-layer (LbL) assembly, which imparted high fire retardancy and desirable hydrophobic to the cotton fabric. Coated cotton fabric was characterized by Fourier infrared spectrometer, scanning electronic microscopy coupled with its energy dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy, conforming that a phosphorus- and nitrogen-containing multilayer coating was homogeneous and uniform increase on the surface of cotton fabric. The resultant cotton fabric achieved self-extinguishing in vertical burning tests and a desired hydrophobic with a water contact angle of 127.4° with only 4BL coating. Moreover, the coated cotton fabrics exhibited a slight delay of ignition accompanied by remarkably decrease of heat release and the fire growth rate index, suggesting the outstanding fire safety. The flame retardancy of coated cotton fabric was enhanced and even not ignited at the heat flux of 25 kW/m2, but the hydrophobic was almost not changed with the increase of bilayer number. Additionally, the relevant analysis of residues and volatile gases manifested that the multilayer coating contributed flame-retardant activities in both condensed- and gas-phase via forming thermally stable char residues and inhibiting the release of flammable gases. Taking advantage of the features, this high efficiency coating together with the facile finishing technique would have great potentials in application of multifunctional cotton fabrics.

Facile synthesis of melamine phytates and its application in rigid polyurethane foam composites targets for improving fire safety

ABSTRACT Biomass melamine phytates (MEL-PA) flame retardant was fabricated by a facile method, and MEL-PA was used to prepare a series of RPUF/MEL-PA composites by one-step water-blown technology. Compared with that of pure RPUF, the degradation rate of RPUF/MEL-PA composites decreased at a high temperature, and the char residues increased significantly, indicating that the thermal stability of the composites is improved. The smoke density test and TG-FTIR revealed that MEL-PA can significantly inhibit the release of smoke, flammable gases (e.g. esters and hydrocarbons) and toxic and harmful gases (e.g. isocyanate compounds, aromatic compounds and CO), implying significant enhancement of the fire safety of RPUF/MEL-PA composites. SEM, Raman spectra and FTIR spectroscopy were employed to investigate char residues of the composites. MEL-PA was found to catalyse the RPUF matrix to form compact char residues with a high graphitisation degree, significantly inhibiting heat and mass transmission processes during combustion.

НАУКОВІ ОСНОВИ РОЗРОБКИ МЕТОДУ ПРОГНОЗУ НЕБЕЗПЕЧНИХ ВЛАСТИВОСТЕЙ ВУГІЛЬНИХ ШАХТОПЛАСТІВ

Purpose: to develop a method of coal gradation to predict the hazardous properties of coal seams during mining. Methodology: based on the study of the interdependence between indicators of the degree of coal metamorphism, which characterize various aspects of its transformation in geological processes. Results: the dependence of the manifestation of any dangerous property of coal seams during mining operations on the influencing factors of the three blocks is considered. In the general case, the most dangerous properties of coal seams include the release of explosive and flammable gases, sudden emissions of coal and gas, the tendency to spontaneous combustion and the occurrence of endogenous fires, increased dust formation, explosiveness of coal dust and other negative phenomena. To prevent emergencies during mining operations, it is necessary to take into account the influence of factors of all three units. Factors of the first block determine the genetic predisposition of mine shafts to the appearance of dangerous properties under the influence of geological processes and metamorphic transformation of the source material. The factors of the second block include mining and geological conditions of coal seams. On the basis of data on parameters of the first two blocks at stages of designing and operation of the coal enterprise, mining indicators of the third block of factors are put. In contrast to the mining-geological and mining conditions of the second block, the factors of the first block are the least studied and not always reliably established. They must determine under the influence of metamorphism changes in the chemical composition, structure and physical properties of coal in the bowels of the Earth, mainly under the influence of elevated temperature and pressure. Currently, more than thirty factors are known, which in different ways characterise the metamorphic transformations of the starting material. There is a practice when in normative documents for the characteristic of degree of metamorphic transformations of layers in the vast majority of cases one indicator is used – an exit of volatile substances at thermal decomposition of coal without access to air. One indicator can not simultaneously and on all sides characterise the content, structure, chemical and physical and mechanical properties of the organic mass of coal and mineral impurities. It is necessary to proceed from the position that each dangerous property of mine layers depends on a certain influence of several factors of metamorphism. Studies have shown that the carbon content directly controls the overall change in the sum of the main components of organic matter (hydrogen, nitrogen, sulphur, oxygen), and the reflection rate of vitrinite – reflects structural changes in petrographic composition. The chemical activity of coal is also affected by the presence of moisture in different states, composition and properties of mineral impurities. The use of each auxiliary indicator must be justified taking into account the purpose of application and the method of its determination Scientific novelty: the carbon content and the rate of reflection of vitrinite in the range of ranking coal by their degree of metamorphic transformations have a reliable quantitative determination, which allows their use in establishing the hazardous properties of coal seams as the main classification indicators. Practical value: the results obtained allow developing general principles of scientific substantiation of the method of forecasting the dangerous properties of coal seams in combination with mining-geological and mining conditions of work on the basis of carbon content and vitrinite reflection index.