Coal Materials Research Articles

Distribution and 13C Signature of Dicarboxylic Acids and Related Compounds in Fine Aerosols Near Underground Coal Fires in North China: Implications for Fossil Origin of Azelaic Acid

AbstractTo understand the characteristics of chemical components and dicarboxylic acids, oxocarboxylic acids and α‐dicarbonyls in atmospheric aerosols at underground coal fire environment, we collected fine aerosols (PM2.5) from Wuhai, Inner Mongolia, North China, where the underground coal fire often occurs. PM2.5 samples were analyzed for the measurements of carbonaceous components, stable carbon isotopic composition (δ13C) of total carbon, and molecular distribution and compound‐specific δ13C of diacids, oxoacids and α‐dicarbonyls. Oxalic acid (C2) was the most abundant species, accounting for 43.2%–63.1% (avg. 50.8%) of total diacids, followed by phthalic acid (Ph) (13.7%). Azelaic acid (C9) was the third most (7.4%) abundant, followed by succinic (C4) and malonic (C3) acids. Significant correlations of C2 diacid with glyoxylic (ωC2) and 3‐oxopropanoic (ωC3) acids and C3 diacid and their δ13C implied that diacids and related compounds were mainly derived from the underground coal fire emissions and subsequent in situ secondary formation. Based on molecular distribution, seasonal pattern and linear relations of C9 diacid with C2, C3, ωC2 and ωC3 as well as with Ph acid and total diacids, together with the comparability and similarity of its δ13C (−27.0 ± 0.9‰) with that of Ph acid and organic matter in coals, respectively, we found that the C9 diacid has been mainly derived from its precursors such as unsaturated fatty acids emitted from underground coal fires and their subsequent in situ photochemical oxidation. However, further research is needed to confirm such an importance of coal combustion for azelaic acid loading in atmospheric aerosols.

Study on molecular structure characteristic and optimization of molecular model construction of coal with different metamorphic grade

To investigate the structural properties of coal molecules with different degrees of metamorphism, in this study, we used Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and solid-state nuclear magnetic resonance carbon spectroscopy (13C NMR) to investigate the structural properties of three coal molecules with different degrees of metamorphism and finally constructed and optimized the coal molecular model. The experimental results showed that with the deepening of the deterioration degree, the proportion of oxygen-containing functional groups in the coal molecules was gradually reduced, the long fatty chains were shortened and reduced, and the aromaticity was enhanced. With increasing coalification, pyridine nitrogen and thiophene sulfur are becoming important components of the nitrogen- and sulfur-containing organic matter in coal. Coal metamorphism promotes the aromatization and condensation degree increase of coal molecular structure, which makes the coal molecular structure evolve into a microcrystalline structure with higher order degree. With this increase of coal rank, the carbon ratio around the bridge (XBP) increased from 0.12 to 0.47. The low-rank coal was dominated by benzene rings with low polymerization degree, and the high rank coal was dominated by aromatic structures, such as tetracene with a high degree of polymerization. The molecular formula of lignite finally constructed was C219H159O21N3, that of coking coal was C235H164O7N4S, and that of anthracite was C286H108O5N4S. The coal molecules constructed in this study provide a theoretical basis for the study of the molecular structure properties of coal with different degrees of metamorphism.

Trace Elements and Consequent Ecological Risks in Mining-Influenced Streams of Appalachia.

Appalachian (eastern USA) coal surface mines fracture geologic materials, causing release of both major ions and trace elements to water via accelerated weathering. When elevated above natural background, trace elements in streams may produce adverse effects on biota via direct exposure from water and sediment and via dietary exposure in food sources. Other studies have found elevated water concentrations of multiple trace elements in Appalachia's mining-influenced streams. Except for Se, trace-element concentrations in abiotic and biotic media of Appalachian mining-influenced streams are less well known. We analyzed environmental media of headwater streams receiving alkaline waters from Appalachian coal mines for eight trace elements (Al, As, Cd, Cu, Ni, Sr, V, and Zn) and assessed the potential consequent ecological risks. Streamwater, particulate media (sediment, biofilm, leaf detritus), and benthic macroinvertebrates (primary consumers, secondary consumers, crayfish) were sampled from six mining-influenced and three reference streams during low-flow conditions in two seasons. Dissolved Cu, Ni, and Sr were higher in mining-influenced streams than in reference streams; Ni, Sr, and Zn in fine sediments and Ni in macroinvertebrates were also elevated relative to reference-stream levels in samples from mining-influenced streams. Seasonal ratios of mining-influenced stream concentrations to maximum concentrations in reference streams also demonstrated mining-influenced increases for several elements in multiple media. In most media, concentrations of several elements including Ni were correlated positively. All water-column dissolved concentrations were below protective levels, but fine-sediment concentrations of Ni approached or exceeded threshold-effect concentrations in several streams. Further study is warranted for several elements (Cd, Ni, and Zn in biofilms, and V in macroinvertebrates) that approached or exceeded previously established dietary-risk levels. Environ Toxicol Chem 2023;42:2651-2665. © 2023 SETAC.

Nitrogen-Doped Porous Carbon Derived from Coal for High-Performance Dual-Carbon Lithium-Ion Capacitors.

Lithium-ion capacitors (LICs) are emerging as one of the most advanced hybrid energy storage devices, however, their development is limited by the imbalance of the dynamics and capacity between the anode and cathode electrodes. Herein, anthracite was proposed as the raw material to prepare coal-based, nitrogen-doped porous carbon materials (CNPCs), together with being employed as a cathode and anode used for dual-carbon lithium-ion capacitors (DC-LICs). The prepared CNPCs exhibited a folded carbon nanosheet structure and the pores could be well regulated by changing the additional amount of g-C3N4, showing a high conductivity, abundant heteroatoms, and a large specific surface area. As expected, the optimized CNPCs (CTK-1.0) delivered a superior lithium storage capacity, which exhibited a high specific capacity of 750 mAh g-1 and maintained an excellent capacity retention rate of 97% after 800 cycles. Furthermore, DC-LICs (CTK-1.0//CTK-1.0) were assembled using the CTK-1.0 as both cathode and anode electrodes to match well in terms of internal kinetics and capacity simultaneously, which displayed a maximum energy density of 137.6 Wh kg-1 and a protracted lifetime of 3000 cycles. This work demonstrates the great potential of coal-based carbon materials for electrochemical energy storage devices and also provides a new way for the high value-added utilization of coal materials.

Development and performance study on low strength and high rockburst tendency similar simulation material of coal

The current similar simulation materials (SSM) are featured with the contradiction between low strength and high rockburst tendency (RT), thus being unable to simultaneously realize the qualitative rockburst of small size specimen and the impact damage restoration of large size model. In this case, this study developed a new SSM of low strength and high RT by using water glass (WG) as cement, talcum powder (TP) as aggregate and adding curing agent sodium silicofluoride (SSF). Under the requirements of initial set volume shrinkage rate (IVSR), long-term volume decay rate (LVDR), uniaxial compressive strength (UCS) and modulus index (MI), the optimal ratios of SSF and TP were obtained 20% and 70% by orthogonal experiment and multiple linear regression method, respectively. Micro-macroscopic experiments such as uniaxial compression, scanning electron microscope (SEM), acoustic emission (AE) and Infrared thermal imager were utilized to monitor in real time the energy-temperature-strength synergistic change characteristics and similarities between this material and the coal with a strong RT. The experimental results show that: the UCS value of this material is 6.11 MPa and its MI is 11.57, which meets the requirements for low strength and high RT. Meanwhile it satisfies a certain similar proportionality between its physical parameters and those of coal. In the whole process of uniaxial compression, there are energy and temperature homologous changes in the characteristics of consistency, and both materials conform to the stress–strain phase law. The infrared radiation temperature displays a trend of “slowly decreasing-gradually warming-continuously cooling-suddenly warming-sharply cooling”. The AE energy count rate shows a trend of “calm transition and sudden increase before and after the stress peak”. All are characterized by strong RT. There is still some difference between the two specimens during energy and temperature changes, due to their different molding characteristics and load-bearing capacity. The feasibility of the material was confirmed in terms of physical parameters, degree of rockburst and homologous energy and temperature characteristics. Meanwhile, this study revealed the multi-parameter precursor characteristics of rockburst damage in the specimen, which can lay a foundation for the prevention and study of impact ground pressure disaster.

Utilizing Low-Cost Sensors to Monitor Indoor Air Quality in Mongolian Gers.

Air quality has important climate and health effects. There is a need, therefore, to monitor air quality both indoors and outdoors. Methods of measuring air quality should be cost-effective if they are to be used widely, and one such method is low-cost sensors (LCS). This study reports on the use of LCSs in Ulaanbataar, Mongolia to measure PM2.5 concentrations inside yurts or "gers". Some of these gers were part of a non-government agency (NGO) initiative to improve insulating properties of these housing structures. The goal of the NGO was to decrease particulate emissions inside the gers; a secondary result was to lower the use of coal and other biomass material. LCSs were installed in gers heated primarily by coal, and interior air quality was measured. Gers that were modified by increasing their insulating capacities showed a 17.5% reduction in PM2.5 concentrations, but this is still higher than recommended by health organizations. Gers that were insulated and used a combination of both coal and electricity showed a 19.1% reduction in PM2.5 concentrations. Insulated gers that used electricity for both heating and cooking showed a 48% reduction in PM2.5 but still had higher concentrations of PM2.5 that were 6.4 times higher than recommended by the World Health Organization (WHO). Nighttime and daytime trends followed similar patterns and trends in PM2.5 concentrations with slight variations. It was found that at nighttime the outside PM2.5 concentrations were generally higher than the inside concentrations of the gers in this study, meaning that PM2.5 would flow into the ger whenever the doors were opened, causing spikes in PM2.5 concentrations.

Production of Carbon Sorbents from Medium-Temperature Coke Siftings of Coking Plants in Central Kazakhstan

The possibility of obtaining carbon sorbents from a fine fraction of medium-temperature coke for the removal of phenols from industrial water and wastewater was demonstrated. This excludes the carbonization of coal material as one of the economically costly stages. The resulting samples were tested for the ability to absorb phenol. The phenol content of water after purification with K12 and ShK sorbents decreased from 251.00 to 0.0572 and 0.737 mg/L, respectively.

Coal-derived rates of atmospheric dust deposition during the Jurassic-Cretaceous greenhouse periods

The study of dust deposition records in geological history is of great significance to the study of paleoclimate evolution during deep periods. Because dust can directly influence the biochemical processes and climate evolution of the Earth. However, the absence of quantitative data on dust limits the systematic and comprehensive study of paleoclimate evolution during deep periods. Prior to the Quaternary period, most quantitative studies on atmospheric dust have focused on the Permian era. However, in the entire Mesozoic era, there are still no quantitative data available on atmospheric dust deposition rates. We utilized the average concentration of inorganic matter in coal from the Jurassic and Cretaceous periods to depict the dust concentration and corresponding dust deposition rate in the atmospheric system during these periods. We also conducted a correlation analysis using the distribution of arid source areas. The results show that the values of ash concentration and dust deposition rates are higher near the arid provenance and lower far away from it. Furthermore, in this study, we have compared the latitudinal variation gradient of dust deposition rates under the icehouse and greenhouse climates by using the end of the Permian and Quaternary as representatives of icehouse climate and the Jurassic and Cretaceous periods as representatives of the greenhouse climate. Our findings indicate that there is a higher ash concentration, dust deposition rate, and dust deposition rate variation gradient in the air under the icehouse climate, while there is a lower ash concentration, dust deposition rate, and dust deposition rate gradient in the air under the greenhouse climate. We have also discussed the dust sources during the Mesozoic period, as well as the differences in ash data under greenhouse and icehouse conditions. This provides a strong basis for studying the atmospheric environment after the modern climate entered the ice age.

Electrochemical Applications of Porous Materials Derived from Coal

As the world shifts from the use of coal to alternatives for electricity generation, including renewable energy, interest arises in developing alternative uses for coal. There are vast U.S. coal reserves, much of which are in historically underrepresented or economically depressed regions. This has created environmental concerns in these regions, especially related to legacy impoundments and other waste coal issues. Finding alternative uses for that coal could create new job opportunities in these regions while also addressing climate change. Currently, there are very few applications for coal outside of its traditional use for electricity production.This group has been developing alternative uses for coal, including uses in energy storage applications. This presentation will discuss the development of macroporous coal materials that then can be further processed into micron or nanometer size particles for porous materials. The characterization of these porous materials will be presented. Graphitized materials for use in lithium ion battery electrodes will be presented. Nanoscale materials such as graphene and carbon quantum dots derived from coal will be presented, along with their application in porous electrodes for batteries and capacitors.

Research on the preparation and diffusion characteristics of coal seam bottom fracture grouting material based on solid waste synergy

Fracture in the top and bottom plates of the coal seams in the Lubei Mining Area of China have developed to communicate with the Austrian gray pressurized water, and the threat of water damage is extremely serious. The rapid development of China's domestic economy has led to an increasing amount of industrial solid waste, which seriously jeopardizes the safety of the ecological environment. Based on the current problem, the slag powder (S) and waste rubber particles (R) were used as the main material, supplemented by cement (C) reinforcement with alkali slag (AS) excitation, and the mine fissure grouting and sealing reinforcement material was developed. The effects of water-cement ratio and (S: R) mass fraction on the physical and chemical properties of the grouted rock mass were analyzed using indoor tests, and the optimal components were determined; secondly, three-dimensional slurry-water-rock flow-solid coupling two-phase seepage simulation was realized using COMSOL, which revealed the diffusion morphology of the solid-waste slurry, preliminarily verified the feasibility of the grouting diffusion inside the rock mass, and determined the diffusion rule of the solid-waste slurry concerning the grouting pressure. The results indicate that at a water-cement ratio of 0.7 and a mass fraction of (S: R) at (70%:30%), the slurry has a flow degree of 275 mm, a water precipitation rate of 7.4%, a 28d compressive strength of 6.9 MPa, and follows the Bingham rheological model, with good injectability. Moreover, the slurry diffuses in simulated fracture grouting in a similar pattern to ultrafine cement slurry, satisfying the reinforcement requirements of field grouting. The research content realizes the combination of mine water damage control and solid waste scale, which is critical to ensuring production safety and the mine's green sustainable development.

Influence characteristics and macro-meso mechanism of pressure immersion time on tensile properties for coal materials

In order to further investigate the deterioration of the tensile properties of the coal pillars supported by the abandoned mine legacy due to the duration of water immersion, this research using a self-developed coal rock pressure water immersion test device to investigate tensile properties' deterioration of coal pillars supported by abandoned mine legacy due to the duration of water immersion, in combination with other equipment (XTDIC 3D full-field strain measurement system, scanning electron microscope, fully automatic mercury compression instrument and X-ray diffractometer), five sets of uniaxial tensile tests on coal samples immersed in pressure water for 0, 30, 60, 90, and 120 days were conducted to investigate the deterioration of tensile properties under different pressure water immersion durations. Longer immersion durations corresponded with decreased uniaxial tensile strength, enhanced plastic damage, poorer integrity of the sample end faces, greater pore probability entropy at the fracture, and increased porosity, average pore size, and median pore size; however, the rate of uniaxial tensile strength tended to decrease, as did the degradation magnitude. The evolution of the deformed localisation zone's displacement misalignment involved the localised zone's penetration, expansion, and development. The immersion time of pressure water is prolongated to improve water-coal rocks interaction and increases the likelihood of dissolution of the Hydrophilic clay minerals and cement within the coal sample's pores. Thus, cracks are more likely to expand and penetrate, promoting the number of channels for pressure water to enter the coal sample, weakening its solid bearing structure, and reducing its tensile strength.

MIL pretreatment on breaking hydrogen bond and swelling of coal: Experiment and simulation

Since direct combustion of low-rank coal is inefficient, expansion and dissolution are essential for better use of coal as an energy source. In this study, [C8mim]FeCl4 molecular configuration was synthesized by quantum chemical simulation method, and Magnetic ionic liquid (MIL) was used to modify coal to improve its swelling efficiency. The FT-IR and Raman properties of MIL were measured by simulation combined with practical methods. Dmol3 was used to study the hydrogen bond changes of coal molecules induced by MIL. When MIL interacts violently with organic matter in coal, the cross-linking network structure generated by non-covalent bonds is destroyed, resulting in the break of covalent bonds such as hydrogen bonds. Further experimental study shows that the pore structure and surface morphology of modified coal samples will be damaged, indicating that the MIL has the ability to dissolve hydrogen bonds and pretreat low-rank coal. It was found by TGA that MIL treatment can increase the tar yield of coal by up to 4.79% and reduce ash content by 3.51%. Through the integration of molecular modeling and experimental analysis, this study elucidates the fundamental principles underlying MIL pretreatment of coal, thereby providing a viable strategy for efficient quality improvement utilization of low-rank coal.

INCREASE IN THE DENSITY OF CARRIER MEDIUM AS A WAY TO CREATE HYDROTRANSPORT OF MINERALS IN LARGE LUMP FORM

Existing coal hydro-transport technologies require preliminary grinding of coal into powder. The same circumstance prevents the use of pipeline transport for the delivery of granite, limestone and other building materials from mining sites to the consumer. With an increase in the density of the carrier medium it becomes possible to supply through the pipeline coal and other solid materials in lumpy form. After the complete regeneration of the carrier medium, the delivered coal or lump material in such a water-salt liquid is no different from that transported by rail. The regenerated working liquid is completely returned to the head of the process.

Characters and Metallogenetic Significance of Organic Matter in Coal from the Daying Sandstone-Hosted Uranium Deposit in the Northern Ordos Basin, China

Coal is usually found in many sandstone-hosted uranium deposits in western China. However, it remains unclear whether coal organic matter is related to the mineralization of uranium in sandstone. In this study, the organic matter of coal containing lenticular carbon plant strips and carbon clastics was analyzed in different alteration zones in the Daying sandstone-hosted uranium deposit located in the northern Ordos Basin. According to geological and geochemical characters, Daying sandstone can be classified into three alteration zones: the oxidation zone, the transition zone, and the reduction zone. The results are as follows. Firstly, the maceral organic matter of the coal at Daying is mostly vitrinite, indicating the characters of humic coal. The maturity of the organic matter is low, which is in the transitional evolution stage of immature lignite or lignite-long-flame coal. Secondly, the kerogen is mainly type III (humic type), which can be easily transformed into humic acid with a strong adsorption capacity for uranium. Thirdly, the vitrinite reflectance (Ro) of the coal organic matter in the transition zone is higher than that of the other alteration zones. Meanwhile, there are bright white bands in the microscopic components of the organic matter of the coal in the transition zone (mineralized zone) and a certain composition of the sapropelite has strong fluorescence. All three aforementioned phenomena are related to the radioactivity of uranium, and each of them possesses the potential for application in mineral exploration. Fourthly, the extraction and separation of humic substances indicates that humic acid plays a key role in organic matter-related uranium mineralization. In the transition zone, uranium can co-precipitate as a humate, and the transition zone’s organic carbon content increases. Therefore, the organic matter in coal contributes to sandstone-hosted uranium mineralization, providing a further guide to prospecting methodologies.

Valorization of a low-quality coal ash, in the preparation of alkali activated inks for applications in 3D additive manufacturing

This paper explores the potential of coal ash-based alkali-activated materials (AAM) for additive manufacturing (AM), coal ash with a high loss on ignition, which is traditionally discarded in landfills. This research evaluated the effect of mineral additions such as metakaolin, CaCO3, and glass residues in AAM. The fresh stage properties were examined by extrudability, shape retention factor (SRF), and buildability. In addition, the microstructure was analyzed by x-ray diffraction (XRD) and scanning electron microscopy (SEM). Mechanical tests such as compression and flexural strength were conducted on the casted and printed AAM. The AAM optimized was employed to print layer-by-layer directly from Crealty Ender 3 with a ceramic extrusion 3D printer kit. The experimental results found that AAM elaborated with alkali activators based on NaOH/Na-sulfate solutions show the best characteristics to be printed: shape retention of 80%, initial setting time of 125 min, extrusion pressure between 160 and 240 kPa, compressive strength of 12.5 MPa, and 5.2 MPa of flexural strength.

Enhancement of biomethane production from coal by supercritical CO2 extraction

The recalcitrant nature of organic matter in coal presents a significant challenge to biomethane production. Supercritical CO2 has gained considerable attention for its unique extraction capabilities. This study uses four coal samples of varying ranks to investigate the promotion mechanism of biomethane production by supercritical CO2 extraction in combination with anaerobic digestion (Sc-AD). Methanogenic potential oxygenated functional groups, intermediate liquid phase products, microbial community structure, and methanogenic metabolic pathways were analyzed between Sc-AD and AD systems. The study found that microorganisms in the Sc-AD system produce more extracellular polymers that enhance the content of aromatic proteins in the anaerobic digestion system. The liquid-phase compounds extracted by supercritical CO2 were consumed by fermentative acidogenic bacteria, significantly increasing the metabolic efficiency of intermediates such as indole and catechol. The reduction in the relative content of carbonyl and carboxyl groups on the coal surface in the Sc-AD system was attributed to the successive attacks by supercritical CO2 and microorganisms on the coal surface. This resulted in the shedding of carbonyl and carboxyl groups from the coal surface, which were then utilized to synthesize small molecule acids. In contrast, hydroxyl groups were retained in the coal. The Sc-AD system exhibited a more stable and efficient microbial community structure in methane production than the AD system. The study demonstrated that supercritical CO2 extraction is a potential method for enhancing CBM recovery and CO2 reduction.

Fatigue Life Assessment of Deck Barge Construction Using Numerical Simulation Methods

Barges are used as the main means of transporting heavy goods such as nickel, wood, coal and other materials that are placed on the main deck and have implications for stress values ​​and construction fatigue life. This study uses a numerical simulation method with the help of ANSYS software. The load simulations given to the main deck construction of the barge are 50% load, 75% load, and 100% load (full load). The results of the numerical simulation detected that the largest stress occurred when the 100% load condition was 190.7 MPa. The stress with 75% load is 160.21 MPa and the stress for 50% load is 129.73 MPa. The fatigue life at 100% load is 10.66 years with a stress cycle of 170000 times, 75% load is 13.49 years with a stress cycle of 300000, and a 50% load is 21.16 years with the a stress cycle of 700000. -

Orthogonal Experimental Study on the Construction of a Similar Material Proportional Model for Simulated Coal Seam Sampling

The development of similar materials is crucial for conducting simulated coal seam sampling experiments. These materials must comprehensively consider the similarity of mechanical properties with raw coal. To ensure a high degree of similarity between the simulated coal seam similar material and raw coal, cement and coal powder were selected as the main influencing factors. This study employed sensitivity analysis and analysis of variance methods to investigate the impact of various factors on the compressive strength, elastic modulus, Poisson’s ratio, and density of comparable materials. The influence of moisture content on the compressive strength and elastic modulus of these materials was also analyzed, as well as the effect of cement and coal powder on moisture content. The results showed that cement was the main controlling factor for the mechanical properties of similar materials. Moreover, the variation of tensile strength and elastic modulus of similar materials in response to the moisture content can be divided into three distinct stages. Based on the influence law, the ratio formula of coal powder and cement for the strength and moisture content of similar materials was obtained, and a proportional model for simulated coal seam sampling similar materials was constructed. The approximate ranges of various parameters that can be achieved by this model are as follows: compressive strength of 1~11.4 MPa, elastic modulus of 0.27~3.62 GPa, Poisson’s ratio of 0.229~0.357, and density of 1.044~1.341 g·cm−3. The error in mechanical parameters for this model has been verified to be within 20%. Finally, similar materials were created for simulated coal seam sampling by employing an appropriate ratio. A self-developed drilling test platform was utilized to successfully conduct an experiment, further demonstrating the reliability of the proportional model.

A proposed method for optimizing coal pillar design using coalfield-specific uniaxial compressive strength

The research described considers whether the variability in coal material strength, as derived through a series of uniaxial compressive strength (UCS) tests, could be used to indicate the variability in coal pillar strength. The aim is to be able to use a distribution of UCS tests as input into the coal pillar strength calculation. This will allow the pillar design to be expressed in terms of a probability of failure rather than as the commonly used safety factor. To achieve this, the bulk strength factor associated with commonly used pillar strength formulae was replaced with a distribution of UCS results divided by an adjustment factor. The factor was determined so as to ensure that the resulting bulk strength does not deviate from the statistically determined bulk strength published in the original formulae. This approach enabled pillar strength distributions to be obtained using industry-accepted strength formulae, subsequently allowing for a probability of failure to be calculated for a specific pillar design. Using a regional coal material strength curve as a baseline, coalfields in which the coal is stronger than the regional mean can be identified and the pillar designs optimized. This is based on the stronger coals achieving lower probabilities of failure at similar safety factors. The research has considered actual UCS data from multiple mines in the Mpumalanga coalfields of South Africa, and has proved that the variability in material strength between coalfields could allow for some optimization using the proposed approach. Based on the data used in the study, a 2.78% increase in extraction could be achieved. However, further research will be required to validate the results of the study in an underground environment.

OPTIMALISASI DESAIN TRUK JUNGKIT CATERPILLAR 777D UNTUK PENGANGKUTAN BATU BARA

In the world of coal mining the use of heavy equipment is absolute. The use of heavy equipment in coal mining is a job that requires optimal production capabilities of heavy equipment, because there are large volumes of excavation work, stockpiling and transportation of material. The standard body design on the Caterpillar 777D dump truck has not been specifically designed for transporting coal materials, so it is not ideal. This study aims to design a dump truck body by adding a larger body capacity than the standard body. The standard used for determining the mass of material to be transported is in accordance with ISO 6483: 1980. After obtaining a new body design using Autodesk Inventor software, the weight of the body and the weight of the coal to be transported will be known, after that the load distribution calculation on the axles will be carried out. front and rear axles. Load distribution will be limited by the maximum load allowed on the front axle and rear axle according to the regulations specified on the Caterpillar 777D unit. Having obtained a new body design with a more optimal transport volume capacity, it will be very useful for more efficient coal transportation. So it was concluded that the results of the analysis of the Caterpillar 777D tub specifically for coal transportation can exceed the standard volume capacity with a volume capacity of 120 m3.