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By F. Calizaya, S. Bhattacharyya

"INTRODUCTION Mechanized underground mines often suffer from noise overexposure. Noise levels are usually above the Permissible Exposure Limit (PEL) where underground fans are used. Sound levels in active workings can reach 121 dB(A), especially when fans are not equipped with silencers. Use of silencers seldom ensure PEL for various reasons. Overexposure of noise induces permanent hearing loss among mine workers. Recent field studies by a NIOSH-funded research project at six coal and non-coal mines revalidated the findings. The University of Utah has undertaken laboratory studies to reduce fan noise at the source. A new silencer prototype with varying noise dampening material has been designed and tested. The silencer and an associated extension which can be repacked with different dampening materials were used in various configurations. Attempts were made to simulate field conditions where installations are quick and not perfect. The test results are presented here. NOISE IN UNDERGROUND MINES Noise induced hearing loss (NIHL) is a chronic problem in the mining industry. In spite of regulations being in place and elaborate hearing protection programs under way, hearing loss is prevalent among the mine workers (Bise, 2001). All production and support machinery in mining generate loud noise often beyond the approved exposure level. Researchers in the U.S. have identified auxiliary fans as one of the major sources of noise that can create noise exposure levels up to 121 dB(A), which is one of the highest in the mining operation (Bauer, 2006). Studies have demonstrated substantial reduction of noise level by using silencers. Adequate fan selection and proper utilization of silencers in auxiliary fans have great potential of abating the problem. In hard rock mines, auxiliary fans are used in blower configuration to ventilate development headings and large production stopes, and also to ventilate underground shops, crushers, conveyor transfer points, etc. Typical duct diameters in hard rock mines vary from 0.91 m to 1.21 m. Silencers are often omitted for cost reduction. In coal mines auxiliary fans are used in exhaust configuration with rigid ducts 0.61- 0.76 m in diameter (Hagood, 1982 and Moreby, 2009) to ventilate working faces in gate-roads and main entry developments. Sometimes, stone dusters are added at the discharge end to dust the roof, ribs and floor. AUXILIARY FANS AND SILENCERS Auxiliary fans are relatively smaller in size than the main fans and often have high rotational speeds (1800 -3000 rpm). Fans are selected based on pressure-quantity requirements and space restrictions only. Noise emissions are rarely considered during the selection stage. Installation of fans, ducts and other accessories is mainly based on best practices, which often do not include noise control. As a result, the operation of an auxiliary or local ventilation system normally produces excessive noise."

Jan 1, 2018

By George S. Austin

Perlite is rhyolitic glass with 2 to 5 percent by weight (wt.%) bound water held within the silicic-glass structure. It is often distinguished by vitreous, pearly luster and concentric perlitic fractures ("onionskin"). Occurrences worldwide are associated with Tertiary to middle Quaternary volcanic rocks. Perlite is in silicic domes, plugs, laccoliths, flows, vitric tephra, chill margins of dikes and sills, and welded ash-flow tuffs. It is a hydrated volcanic glass formed through secondary alteration of obsidian by the incorporation of water into the glass/silica structure. Post-emplacement hydration (weathering) of cooled glasses by meteoric water is the principal alteration process, but some hydration by magmatic or meteoric water during or shortly after emplacement, or hydration by water exsolved during cooling may occur. Commercial "perlite" is any volcanic glass that expands or "pops" when heated quickly to plasticity while evolving steam and thus forming a lightweight, frothy material. The expansion temperature typically ranges from 1,100 to 1,500°F. An expanded volume increase of 10 to 40 times the original volume yields expanded densities of 1.5 to 11 pounds per cubic foot (lbs/ft3). Perlite is mined by eight companies at 10 operations in six western states. New Mexico accounts for more than 80% of the total tonnage mined. The rest comes from Arizona, California, Colorado, Idaho, and Nevada. In 1992, domestic production was 571,000 short tons (st), domestic apparent consumption was 591,000 st, and the value of crude perlite was $15.3 million. In 1991, with about the same production and price of crude perlite, the gross value for expanded perlite was $101.7 million. Perlite exports in 1992, primarily to Canada, are estimated an 30,000 st; and imports, from Greece, are an estimated 50,000 st. In 1992, 70 plants in 33 states expanded crude perlite. Construction uses of expanded perlite accounted for 66% of total domestic sales. Expanded perlite used as filter aid accounted for 15%. All other markets, including use as a filler and in agriculture, accounted for 19%. Leading states for expanding perlite, ranked by order of sales, were Mississippi, Pennsylvania, California, Illinois, and Georgia. Domestic perlite encounters transportation disadvantages in some areas of the eastern United States compared to perlite imported from Greece. However, western U.S. perlite exports to Canada offset this in large part, and net import reliance for perlite is about 3% of domestic consumption. Perlite grab samples were tested at the New Mexico Bureau of Mines and Minerals Resources (NMBMMR) for their basic suitability in horticulture, construction, filter aids, and fillers/extenders using Perlite Institute techniques modified by the NMBMMR. Most commercial perlite ranged from 2.5 to 3.0 wt.% bound water for all major types (classical, granular, and pumiceous). Expanded density varied widely, but the lowest density of 1.9 lbs/ft3 was for granular. Average brightness of expanded perlite was 47.6 to 69.3%. Nonexpansibles, commonly obsidian or "dead" perlite, ranged from 18 wt.% to less than 1 wt.%, with granular perlte generally the lowest. Compacted density was not related to either perlite type or nonexpansibles present. Sieve analyses of the -50+100 mesh product showed that, in general, pumiceous perlite produces more fines and classical and granular perlite average 60 to 80% -30+100 mesh after expansion. Samples were tested for crystalline silica that ranged from below the detection limit of 0.5 wt.% to nearly 0.2 wt.%, but most tested below 0.5 wt.%. Although quartz content can be lowered in the expanded product by the expansion process, producers can further lower crystalline silica in the product by mixing low-quartz crude with high-quartz perlite before expansion. Chemical analysis by x-ray fluorescence confirms the rhyolitic composition of perlite, but indicates that surface weathering may increase the concentration of some elements, such as potassium and calcium, by infilling cracks or fissures developed during or after perlite emplacement.

Jan 1, 1995

By R. Tamir

This paper will describe the benefits of utilizing the decision support system, DSS to support the methodology of structured decision-making in the mining environment. It will outline the layers of the mining related decision making – 1. Creation of “one truth” situational awareness utilizing 2. existing planning, ERP, operational and monitoring agents, a. Expressing plan verse performance across mining phases and functions compared with the actual and trends to evaluate performance. b. Creating alternate courses of action and the implications up and downstream. 3. It will review the current condition were although a multitude of technologies resolve multi variable issues they do not interact in a way that assists decision makers throughout the organization in making high-quality decisions that will push the overall performance envelope. 4. The paper will show the benefits of integrating military methodologies to resolve multi variable complexed issues (operational, financial and other), operating in changing environments in order to meet time sensitive objectives with restricted resources. This is achieved by creating a shared situational awareness thru incorporating information from a multitude of data generating agents, creating COA, selecting the appropriate and turning it into a plan. The paper will discuss the implementation and suggest a path.

Feb 1, 2023

By R. Wisniewski

Every underground coal mine in the United States must deploy and operate a wireless communication and tracking system. This paper addresses the reliability and availability of an installed tracking system and the communications infrastructure that supports it. A particular interest is the requirements for the systems to operate continuously without failure after a mine disaster for 96 hours, and the requirements in the MINER Act for the tracking systems to be ?calculated to be serviceable? and the communications systems ?redundancy?. These requirements imply a certain reliability and availability. This paper describes a quantitative way to assess these systems requirements, using the tools that are available and commonly used by the Reliability, Maintainability, & Availability community.

Feb 23, 2014

By S. B. Kim, J. Hong, K. Park, W. Kim, H. Kim, Y. Han, J. Choi

"For the first time, the influence of stearyl trimethyl ammonium chloride (STAC) as a collector, on the flotation behavior of lepidolite (Uljin, South Korea) was systematically examined in Denver Sub-A cells. Flotation tests were carried out by varying amount of STAC (50–200 g/ton), feed size (-65, -100, -150, and -200 mesh), and solution pH. The impeller speed of 1000 rpm, flotation time of 10 min and AF-65 (a frother) of 250 mL/ton were invariably applied. In order to complement flotation experiments, zeta potential measurements and XRD analysis were conducted. XRD results showed that the ores were mainly composed of lepidolite, muscovite, quartz, calcite and albite. In addition, zeta potential results showed that isoelectric points were about 2.5, 2.3, and 9.7 for quartz, albite, and calcite, respectively, and lepidolite was determined to be less than 2. Overall, the results of 3-stage flotation showed that Li2O grade and recovery tended to increase with increasing STAC dosage and decreasing feed size. In addition, Li2O grade increased with decreasing pH. The results were explained by the extent of the interaction between STAC and each mineral.INTRODUCTION A great number of potential applications of lithium are being developed currently by the thermonuclear fusion power generation industry(1,2) as well as by the battery and fuel cell industry(3). Even though lithium is mainly consumed in the form of lithium metal and some lithium compounds, about 10% of total lithium production is consumed directly as mineral concentrates by the ceramic industry for the manufacture of special ceramics and mica based glass-ceramics(4). Granitic pegmatites normally contain feldspars, quartz, and mica in addition to lithium-bearing minerals such as spodumene (LiAl(SiO3)2), petalite (LiAlSi4O10), and lepidolite (KLi2Al(Al,Si)3O10(F,OH)2). The amount and grade of metallic minerals tend to gradually decrease and become lower, leading to the increase in the price of base metal or metallic compound(5). Accordingly, recent studies have been extensively devoted to developing the technique to improve the grade of metallic minerals from low grade metallic ores(6,7). Nevertheless, studies regarding the improvement of Li grade from lepidolite ores are very scarce. Lepidolite is a phyllosilicate mineral of the mica group and is often associated with other minerals such as calcite, muscovite, feldspar, and quartz, which need to be separated for lepidolite enrichment(8). Many studies have reported the flotation techniques for separating calcite, muscovite, feldspar, and/or quartz from various targeting minerals(9-11); however, there has been no attempt to investigate physico-chemical properties of lepidolite and its separation from such types of gangue minerals through flotation. Hence, in this study, for the first time, flotation has been carried out for the quaternary ammonium salts (stearyl trimethyl ammonium chloride (STAC, (CH3)3CH3(CH2)16NCl))-lepidolite system based on only the electrokinetic property of minerals that consist of lepidolite ores without adding any depressant to get an initial insight on its flotation behavior. The experimental variables that influence the lepidolite flotation such as amount of collectors, feed size and solution pH have been also examined."

Jan 1, 2015

By Kenneth E. Merklin

The heavy media process is now being used extensively throughout the world for the gravity concentration of a great number of different minerals. The process is a commercial adaptation of the heavy liquid procedure which has been used in laboratories for many years to separate mineral of different specific gravities. In the heavy media process, a suspension of finely divided particles in water is used to increase the apparent specific weight of the fluid to the desired separating point. The original heavy media process used sand, galena, pyrite and occasionally other materials as the solid constituent of the separating suspensions. As the process developed, the need for a more universal media meeting the following requirements was recognized: 1. High specific gravity. 2. Resistance to abrasion. 3. Resistance to corrosion, 4. Readily reduced to a suitable size consist for suspension in water. 5. Available in quantity at economical price levels. 6. Easy to recover by a simple method.

Jan 1, 1958

By Trevor R. Ellis

In August 2011, the Southern African Institute of Mining and Metallurgy (SAIMM) contacted mining institutes and related societies internationally to assess their interest in participating in coordination of the review of the South African Code for Mineral Valuation (SAMVAL) with reviews of other mineral valuation standards. The main mineral valuation standards are the CIMVal Standard of The Canadian Institute of Mining, Metallurgy and Petroleum (CIM), the VALMIN Code of The Australasian Institute of Mining and Metallurgy (AusIMM), the SAMVAL Code, and the extractive industries? guidance note of the International Valuation Standards Council (IVSC), Valuation of Properties in the Extractive Industries, GN 14, designed for application within the full set of International Valuation Standards (IVSs). By January 2012, SAIMM had concluded that the level of respondent interest was adequate to organize a meeting. A meeting was scheduled for April 18, 2012 in Brisbane, Australia in conjunction with a VALMIN mineral valuation conference organized by the AusIMM. The stated purpose of the meeting was to develop an accord on terms of reference for pursuing harmonization of mineral asset valuation standards adopted by the participating mineral institutes. SME decided that, although it has not developed its own mineral valuation standard, it should participate in the Brisbane meeting and the harmonization process, as also did the American Institute of Minerals Appraisers (AIMA).

Jan 1, 2012

By Henrique D. G Turrer, Desmond Edifor, Marcello R. Cruz, Josue M. de S Junior, Darius Wonyen

A geometallurgical testing program was developed to anticipate ore behavior in the beneficiation plant and support production planning. Over 100 drill core samples from a major iron ore deposit were tested using bench-scale gravity and magnetic separation methods to assess variability in process responses. Results showed significant differences in key attributes such as iron grade, gangue content, slimes generation, and specific gravity, directly impacting concentrate grade, recoveries, and tailings quality. Correlation analysis and regression models were used to link feed properties to process outcomes, and a mass recovery estimation equation (Wrec) was developed for predictive use. The study proposes the integration of geometallurgical parameters—such as Fe, SiO2, Al2O3, LOI, ore type, size fractions, and slimes content—into the block model to support blending decisions and minimize operational risks. This work establishes a solid foundation for long-term mine-to-plant integration, with future phases aiming to expand testing and build a calibrated geometallurgical model.

Feb 22, 2026

By Tom Michaud, Rob Albinger, Ian Turner, Michael Rispin

Data transmission, communication, tracking, and the connection of equipment such as gas detectors, cameras, and collision avoidance systems in today's tunnel industry are critical pieces of the constructor's infrastructure. Reliability, flexibility, redundancy, and cost-effectiveness are key in selecting and implementing inte- grated systems. Both wired and wireless components are used to deliver custom solutions and can involve interconnectivity between backbones. Systems integration is important as industry adopts proven technologies from other industries. Case stud- ies are given showing how tailor-made approaches deliver needed functionality, with varying degrees of com- plexity, in various classifications of environment, in order to meet a project need.

Jun 23, 2024

By J. A. M. Cano

Introduction Since the beginning of operations at the pellet plant at Ponta Ubu ES, Samarco Mineração SA has produced pellets for direct reduction and blast furnace processes. Of the total amount of pellets produced from 1977 through 1993, 55 % are used in the blast furnace, about 45 Mt (49.6 million st). The principal components of pellet gangue are calcium oxide, magnesium oxide, silica and alumina. They should be added in adequate quantities to guarantee the mechanical resistance of the fired pellets under blast furnace conditions. Over the years, the pellets produced by Samarco had a silica content between 2.5% and 2.8% and varying binary basicity preferably between 0.8 and 0.85. On the other hand, the increasing amount of industrial waste in siderurgical plants caused by the increase of steel production has caused some countries to put into practice methods to reduce the volume of slag produced in the blast furnace. This paper's goal is to find an alternative for decreasing the amount of slag produced in the blast furnace. It is possible to decrease pellet gangue by decreasing the silica content to about 2%, leaving the metallurgical properties and quality of pellets unaltered. For this work, Samarco pellets were used with Si02 between 2.5% and 2.8%, pellets with high silica and pellets with Si02 between 2.0% and 2.3% low silica. Both were partially fluxed by the range of varying basicity CaO/SiO2 from 0.8 to 0.95 during production. Experimental tests on pilot scale Thhis work began in January 1986 in the pilot plant (pot grate, Fig. 1) at Samarco. Its goal was to obtain preliminary data that would indicate the bybility of the project. It also formed a solid base to extend the studies in tests on an industrial scale of production for blast-furnace pellets. The pot grate is a test furnace composed of a gas burner, a combustion chamber and a grate, connected by hot air ducts. The burner is fed by a mixture of LPG and air. It reaches high temperatures through oxygen injection. The combustion chamber heats the air that comes from the turbocompressor. This hot air flows through the ducts to the grate on which the pellet samples are fired. During updraft drying, downdraft drying, preheating, firing and afterfiring, the upward and downward direction of the air flow can be controlled by valves driven by pneumatic cylinders. The pot grate indurator was fully automated in August 1989. Positive and negative pressures measurements resulting from gas passing through the pellet layer, as well as temperature readings, are recorded in graphs in relation to time for all tests. The tests depend on the various steps carried out in sequence that can influence the results of the tests. Therefore, some criteria were adopted to restrict the number of variables in the process. This was done to facilitate the results of the analysis. The pellets were composed of concentrate, bentonite, hydrated calcitic lime and metallurgical coal, all regularly used in the pellet plant. The material balance of the pellets mix was determined from the chemical analysis of the components. Table 1 shows the chemical characteristics of the concentrate and the additives used in the pilot plant and industrial tests. The basicity has a marked influence on the metallurgical properties of the pellets produced by Samarco with a silica content between 2.5% and 2.8%. However, for pellets with low silica (about 2%), it was necessary to study the variation in the parameters of quality in a wide range of basicities to deliniate with precision a scope of work. A large variety of low-silica blast-furnace pellets were produced at the pilot plant with binary basicity varying between 0.8 and 0.95. After chemical analysis, those pellets were separated into five groups of different binary basicity (0.8, 0.84, 0.87, 0.90 and 0.95). Each was then split, one part for metallurgical tests in the laboratory at Samarco and another to be evaluated in a laboratory for metallurgical tests in Germany. It was agreed that the tests to evaluate the quality of the pellets in the two [ ]

Jan 1, 1996

By B. Anameric

Considerable effort has been directed towards understanding the carbothermic reduction mechanisms of self-reducing, fluxing dried green balls to produce pig iron nuggets. Given the geometry of the situation, some investigators believed that the shrinking core model was applicable. Hence, this study involved investigation of the applicability of the shrinking core model to pig iron nugget production. The experiments involved heat treatment of dried green balls utilizing either a laboratory-scale resistance box furnace or a gas-fired muffle furnace at various furnace temperatures and residence times. The products were analyzed for the following: (i) preferred reaction pattern, (ii) distribution of the metallized areas, (iii) % iron content variation in the pig iron nuggets from surface to center, (iv) carburization pattern and (v) physical and chemical properties of the pig iron nuggets. It was determined that the reduction of iron oxide occurred simultaneously throughout the sample and not beginning at the surface and propagating inward; thus the shrinking-core model was not applicable. Heat transfer and gas diffusion from surface to center were not the rate-limiting steps for reduction and carburization reactions.

Jan 1, 2011

By Wilbur J. Morin

Construction of Flaming Gorge Dam in northeastern Utah necessitated the construction of a new state highway, Utah-260, to provide access to the dam and the town of Dutch John. A 550-foot arch structure was designed to span Cart Creek, about one mile southwest of the dam. The rock exposed at the site is highly fractured quartzitic sandstone with interbedded shale of the Precambrian Uinta Mountain Group. Eight exploratory holes were drilled, four in each abutment area, to determine rock types, the extent of fracturing at depth and rock strength. Drill cores in the west abutment revealed blocks of quartzitic sandstone loosened by the weathering and partial removal of underlying shale beds. The rock in the east abutment area was found to be highly fractured to depths of 70 feet and as far east as 50 feet from the footing locations. Selected core sections were tested for unconfined compressive strength but the values were not considered-representative of the in-situ fractured rock. To prevent movement along or, perpendicular to open fractures, four drilled-in columns were provided at the base of each footing. These extended 50, feet beyond the base of the footing, along the bearing and inclination of the thrust reaction.

Jan 1, 1963

By J. J. Antony

The Cactus Gold Mine is a joint venture comprised of Middle Buttes Partners Ltd. (CoCa Mines, Inc.--operator, T. Congdon and W. Carey) and Compass Mining, Inc. The project includes 2.4 sq. miles of contiguous mining claims and leases in the Mojave Mining District, Kern County, California, approximately B5 miles northeast of Los Angeles. The property is readily accessible year round by all-weather roads and is within 6 miles of the main line of the Southern Pacific Railway.

Jan 1, 1988

By S. Acar

The results obtained for the selective flocculation or flotation of natural ores do not usually agree with the corresponding properties of the constituent minerals when present alone. This is mainly due to the presence of dissolved mineral species which can interact in many ways with other components in the system and alter their behavior. In this paper, the effect of dissolved species on the flocculation and electrokinetic properties of sulfide minerals is disscussed. Dissolved Fe, Cu and Ni species are found to affect the properties of chalcopyrite, pentlandite, millerite, pyrrhotite and covellite in certain pH range. These effects are interpreted in terms of species adsorption leading to activation or depression of reagents, surface precipitation and complexation of species, etc.

Jan 1, 1985

By J. S. Gardner, R. Woolacott, P. D. Robinson

In 1917, U.S. Coal and Coke Company, a subsidiary of U.S. Steel, opened Mine 31 and built the community of Lynch, Kentucky. For the time this was truly a major engineering accomplishment. It was documented in Howard N. Eavenson’s 1939 AIME paper, “Coal Through the Ages.” In 1996, Arch Coal donated the Portal 31 property to Harlan County for public use. In 2003 the Southeast Education Foundation, Inc. and the Kentucky Coal Museum plan to open the Portal 31 Exhibition Mine to the public to tell the story of Kentucky coalmining through the decades. This presentation will summarize the history of the project, efforts to bring it to reality, the engineering problems, and the challenges of providing a safe environment for visitors.

Jan 1, 2003

By N. Careddu

In recent years, slabs with a rough surface have captured a large share of the ornamental stone market. However, the main technologies used for this type of treatment are based on mechanical shock (bush-hammering) or thermal treatment (flaming or flame-finishing). These traditional technologies are widely used, but have many limitations that decrease their usefulness. The purpose of this study was to develop a technology that enhances the natural colors of the rock and produces a rough surface without compromising its mechanical characteristics, in contrast to traditional technologies. This report shows the technical, economic and aesthetic results obtained with a new water-jet treatment and compares it with competing technologies.

Jul 1, 2010

By B. M. Davis

The problem of assessing uncertainty in grade estimates has been a topic of research and debate since kriging was first introduced. Use of the kriging variance was originally touted as all that was necessary in order to produce confidence limits for grade estimates. Since then the prudence of using the kriging variance for confidence interval estimation has been questioned, and techniques such as the jackknife and conditional simulation have been proposed to develop "true" interval estimates. This paper compares the differences between interval estimates produced by the three methods and makes conclusions about the performance of confidence intervals produced by the different methods.

Jan 1, 1997

By J. J. Moore

Combustion synthesis, or self-propagating high-temperature synthesis (SHS), reaction systems are discussed with respect to thermodynamics and kinetics. In particular, the effect of the process parameters, e.g. particle size, [All] ignition and combustion temperatures, on these self-sustaining reactions is discussed. Combustion theory is used to investigate the effect of the overall actuation energy of the SHS reaction on the combustion front propagation rate and in obtaining a clearer understanding of the transition from stable to unstable propagation. Finally, examples of the application of combustion synthesis to advanced materials processes are made, in particular the synthesis of Ni-Ti-X intermetallic shape memory alloys, TiC-AI2O3 and ZrB2-AI203 ceramic composite materials.

Jan 1, 1992

By Ronald G. Schmidt

AND SOME RIN UP HILL AND DOWN DALE, KNAPPING THE CHUCKY STANES TO PIECES WI' HAMMERS, LIKE SAE MANY ROAD MAKERS RUN DAFT. THEY SAY IT IS TO SEE HOW THE WARLD WAS MADE. Sir Walter Scott St. Ronan's Well - 1824 In the minds of many, geologic exploration has advanced little since the early nineteenth century. In truth, despite the development and refinement of new and potentially valuable technological tools, the approach or philosophy of the explorationist has received meager attention in professional literature. In many areas, the explorationist relies upon experience, subjective judgement and general intangible inspiration, often traveling together under the misleading pseudonym of "art," in achieving both an exploration plan and in making the myriad day to day decisions necessary to the execution of that plan. Without a solid, objective basis for decisions, exploration under this concept is little more than guesswork largely by intuition, and it is small wonder that many exploration programs flounder in a sea of over-expenditure inefficiency or fail to fulfill their expected goals within the funding which has been provided. From a rational management point of view, such a state of affairs is frustrating and inconsistent with the application of the same scientific principles which are presumed to be the basis for the exploration methods which are used. This somewhat presumptuous point of view cannot be extended as a general condemnation of the many exploration programs which are both technically and economically successful. On the other hand, the

Jan 1, 1968

By Guangyao Si, Ismet Canbulat, Xun Luo, Yi Duan

Routine analyses of seismicity and event locations are essential for coal burst risk management, especially in the presence of unfavorable and complex geology. In an Australian longwall coal mine, a small-scale seismic monitoring network was installed to monitor a section of a major dyke intersected by the roadway, which was classified as a coal burst prone zone. The Deep Convolutional Neural Network (DCNN) technique was adopted for automatically discriminating seismic events to assess seismicity in this zone. The discriminated seismic events were located with the Shortest Path Method based on the Boundary Discretization Scheme (BDS-SPM) for temporal-spatial seismic event distribution analysis. The results demonstrate that the seismic events are discriminated with an average accuracy of 94%. Moreover, the seismic events are more accurately located using the BDS-SPM with a 3D heterogeneous velocity model compared with results obtained with a homogeneous velocity model. The temporal and spatial variances in seismic activities identify that the rock fractures in the dyke zone are closely related to the longwall mining process and a local dyke has a controlling influence on the stress concentration in its vicinity.

Apr 26, 2022