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By F. G. Miller

In mid-1972 we determined that a fresh approach to coal mining research was needed for the industry as well as for Bethlehem. The reasons to us were obvious: Productivity was in the throes of a steady decline, and labor and maintenance costs were spiraling upward. Yet, despite this predicament, nowhere in the U.S. at that time was there a comprehensive and coordinated research and development plan in the offing. The Bureau of Mines had not yet been charged with such a responsibility, and industry was content to rely on machinery manufacturers for innovations. After studying our own mining practices, the state-of-the-art of mining research elsewhere, and development work by manufacturers, we presented a comprehensive research package to our management at the end of 1972. The ideas and experience of many operating and management personnel in our Corporation contributed to the formulation of the final plan as approved.

Jan 1, 1976

By Harald F. Solberg

A preliminary study of the performance of a 4-inch Krebs cyclone at near rope conditions and different feed slurry temperatures was completed. Results suggest that temperature influences the x50c size which, in turn, did not depend upon spigot diameter. The bypass correction to a reduced efficiency equation incorporating the concept of a critical size xo was a function of fractional water recovery to underflow and may depend on feed size and feed percent solids. Further experimentation is required to develop an accurate model at near rope conditions.

Jan 1, 1981

By Heinz C. Dittmar

The phenomenon of radioactivity has been known since the turn of the last century. Scientists of many nations, intrigued by the strange effects of radioactivity, have engaged in research to probe the heretofore presumed, but largely unknown world of atomic structures and subatomic- particles. A theory evolved of splitting the atom, thus providing insight into the structure of matter and opening the way to possibly create new materials. Many years of effort culminated in the first chain reaction in 1942. The beginning of the atomic age was drastically demonstrated by the flash of the large scale chain reaction of the first atom bomb. It was actual proof of the incredible energies contained in matter.

Jan 1, 1966

By Z. Rogovin

In order to develop more accurate procedures for scale-up and design of semi-autogenous-grinding mills through detailed mathematical models, a better understanding of the charge motion and rock/ball segregation is needed. To achieve this a 0.61 m (2.0 ft) diameter x 0.305 m (1.0 ft) length plexiglas mill was constructed as a scale model of a commercial SAG mill. Rock motion in the rotating mill was simulated using various sizes of ceramic balls. Quantitative measurements of dynamic angle of repose, water and slurry motion, holdup and size segregation of the charge were taken. In addition, a video-presentaiton (available to the public) was prepared to elucidate charge and water motion at various mill speeds, charge volumes, rock size distribution and flow rates.

Jan 1, 1985

By Frank Ruskey

Many problem associated with potential hazards in a proposed mining area may not be adequately appraised because of the complexity of trying to evaluate them in terms of production requirements. Frequently, encountered hazards have to be dealt with by day-to-day operational schemes that require the miner to either force a way through them or avoid them by blocking off the area in which the hazards are known to exist. These considerations, after the mine is in full production, can be costly to the mine operator and can increase the danger to the miners. A hazard-evasion computer program for mine planning that will appraise proposed mine layouts on the basis of existing or potential hazards has therefore been developed. The program is intended for use during the planning phase of a mine, where it should assist the mining engineer in making decisions in mine design. With the output from this program, the mining engineer should be able either to corroborate his judgments made on the basis of mining experience or to find unanticipated solutions to design problem. The program tests hundreds of possible solutions to a mining layout, and by sorting out the 10 best (based on a criteria of minimum-abandoned-coal) limits the number of choices that need to be considered and appraised for applicability to a given mine scheme.

Jan 1, 1973

By Qingwen Shi, Yun Zhao, Brijes Mishra

The effect of discontinuities on the fracturing and mechanical behavior of shale has been extensively investigated on a laboratory scale in previous works. It is well agreed that the lamination properties, including discontinuity and lamina properties, affect the behavior of shale. However, it is still unclear how the lamination properties are affecting the stability of the shale roof in an underground coal mine entry. This paper investigated the effect of lamination properties using the discrete element method on a mine-scale entry model as an extension to the previous work conducted on laboratory scale models.

Jan 11, 2022

By M. E. Buzon, M. E. Gunter, B. D. McNamee

A Google search on talc asbestos yields more than 500,000 hits due to the growing number of civil lawsuits in this area. Historically, the litigation was centered on amphibole-containing industrial talc. There was no debate these talcs contained amphiboles, but the issue was the definition of asbestos and whether the amphiboles had an asbestiform habit. Ultramafic-hosted talcs, however, are formed in such a way as to not favor the formation of amphiboles in the talc, but they can occur in the surrounding black-wall. In these deposits, the serpentinite host rock is in direct contact with the talc, therefore, allegations can be made that non-asbestiform amphiboles or non-regulated serpentine group minerals can occur in the final products. We analyzed talcs from both metamorphosed carbonate- and ultramafic-hosted talc deposits using polarized light microscopy (PLM), scanning electron microscopy (SEM) with energy-dispersive spectroscopy (EDS), electron microprobe (EPMA) with wavelengthdispersive spectroscopy (WDS), transmission electron microscopy (TEM) with EDS, and powder X-ray diffraction (XRD). Compositions of minerals determined by EDS alone are not sufficient to confidently identify asbestos, despite common practices by some researchers. We emphasize, using both historical samples, and analyses of currently contested minerals, the importance of determining both the structure and composition of a mineral, as well as defining its morphology, before concluding whether it is asbestos.

Jan 1, 2018

By Nilufer Kursunoglu

Despite being crucial for meeting the world’s energy demands, coal mining operations present considerable health risks, especially when it comes to exposure to coal dust. Longwall coal mining, an advanced technique, has considerably enhanced production but made dust control more difficult. Due to its explosive nature, coal dust continues to be a serious and dangerous concern in the industry despite developments in safety technology. This study aims to comprehensively assess the risk of coal dust explosions by integrating fuzzy risk matrix and Pareto analysis methodologies, offering precise risk ratings for various root causes. A fuzzy risk matrix was developed to assign exact risk ratings to identified root causes. Additionally, a Pareto chart was used to identify the main reasons and suggest particular preventive measures. 17 significant causes were determined for underground coal mines based on the study’s methodology, and some preventive measures were suggested. In accordance with fuzzy risk rating values, root causes were divided into six categories. The root hazard with the highest risk rating was identified as ‘accumulation of inflammable gas/gases’. The proposed approach was used to examine incidents caused by coal dust explosions in Turkish coal mines in order to demonstrate the effectiveness of combining the fuzzy risk matrix and Pareto analysis for assessing coal dust explosions. This study gives not only a solid framework for risk assessment but also critical information for classifying the risks associated with coal mine dust explosions. The results highlight the critical necessity for proactive and preventive actions to reduce the hazards of coal dust explosions and protect the safety of mining workers.

Nov 16, 2023

By Jue Kou, Lei Yu, Bern Klein, Lusheng Zhou, Chunbao Sun, Genzhuang Li, Reem Roufail, Amit Kumar

Magnetic liners can improve the performance of ball mills by increasing grinding efficiency, extending service life, and reducing maintenance costs. Despite their importance, the fundamental understanding and the quantitative investigation on the effects of the magnetic liners has not been addressed in the literature. This paper addresses this gap by studying charge motion, and how the use of a magnetic liner affects the breakage mechanism of the mill, using discrete element method (DEM) modeling and the Hertz-Mindlin contact model with relative velocity dependent (RVD) rolling friction. Charge motion was modeled under different mill speeds. Compared to conventional steel and rubber liners, the charge motion in the magnetic liner mill was predominantly cascading. Quantitative analysis of the energy dissipation within the mill was conducted to investigate mill breakage. Regardless of speed, over 50% of the total energy dissipation in the magnetic liner mill was in the form of abrasion and attrition. The results highlighted the appeal of magnetic liners in secondary and regrinding application, where abrasion and attrition are considered more efficient in the fine material breakage, and where impact is ideally minimized to reduce mill wear. A number of experiments were conducted to assess the effect of different model parameters on the performance of the magnetic liner mill. The highest abrasion/attrition intensity was observed with high values of the model parameters namely the restitution coefficient, static friction coefficient, and rolling friction coefficient.

By Calvin L. Stevenson

The probability of a particle passing through a maze is predictable and consistent. This principle may be utilized to effect a particle size separation of materials by presenting a physical maze to a stream of material that will allow the fine particles to pass, while deflecting the coarse particles. A maze is effective even though all apertures encountered are many times larger than the particles being separated. By designing a machine that allows the probability parameters to be controlled and varied without changing physical dimensions, probability sizing becomes a useful tool for the separation of granular materials.

Jan 1, 1967

By J. D. Kennedy

The alchemists of old are remembered well for their tireless efforts in attempting to convert various common metals, such as lead, into gold. Not so well known generally, but no less intense, have been the efforts of certain individuals who attempted to manufacture diamonds over the last 100 years. Diamond, the most glamorous and permanent of gems and the hardest industrial abrasive, is carbon in a high-density unique crystalline form with a cubic structure and a density of 3.5. This contrasts with graphite at a theoretical density of 2.2 and possessing a hexagonal structure. Diamond is the hardest natural, material known and until very recently had no close competitor, natural or otherwise, with respect to hardness. The hardness of diamond exceeds that of any other industrial abrasive by a factor of approximately five. The early theories of diamond synthesis were rather vague. Since diamonds occurred in nature, man then looked to nature for clues as to how this might be accomplished. The original known diamond deposits of India are alluvial in character and provided little insight as to how diamond had been formed by nature, for in, these locales the diamonds have been washed by streams or carried by the glaciers long distances from the areas in which they occurred originally in the earth's crust. As a matter of fact, we are told that even today the locations of the mother ground for the Indian alluvial deposits are not known.

Jan 1, 1959

By R. E. Lund

The design, operation, and performance of an integrated pilot plant for recovering zinc and copper from a complex sulfide ore are described. Metallurgical processing comprised selective sulfate roasting in a fluid bed, leaching in a weak sulfuring acid solution, recovering copper by cementation with scrap iron, air oxidation to remove soluble iron, more-or-less conventional purification for removal of impurities deleterious to zinc electrolysis, recovering zinc by electrolyzing solutions, and recycling spent electrolyte to the sulfating roaster. The effects of several feed preparation and roasting variables on the sulfation response of zinc, copper, and iron are set forth, together with the electrolyzing characteristics of the zinc solutions.

Jan 1, 1962

By M. G. Ayat

Although other methods of mineral concentration have been developed over the years, gravity separation remains one of the most efficient and economical for cleaning coal. The concentrating table and the spiral separator are popular devices used for the separation of minerals by exploiting the differences in specific gravities of the product material and the gangue. While the former device has been servicing the coal industry for over 75 years, the latter seems to have not been employed extensively for coal cleaning purposes in this country. As far as coal preparation is concerned, both separatory devices seem to be most efficient for intermediate to fine size fractions. As it stands there exists a great deal of confusion amongst preparation engineers and plant managers as to whether spirals can have a place in the coal industry. If so, whether their come back is the beginning of the end for concentrating tables, or can they be employed along with concentrating tables to contribute toward more efficient cleaning processes resulting in an improvement in the overall economics of the coal preparation industry. This paper examines the efficiency of both systems for coal processing operations as well as the basic principles, operational variables, economics, advantages and disadvantages associated with each unit operation. Attempts have been made to draw conclusions and make recommendations as to which system would be more beneficial for coals of known characteristics.

Jan 1, 1986

By Subhash Bhagwat

The definition of high sulfur coal varies from plant to plant and is subject to changes over time as the environmental regulations change. In plants constructed after September 1978 hardly any domestic coal can currently be burned without the use of Flue Gas Desulfurization (FGD) because a 70 percent reduction in potential S02 emission is mandatory even when the potential emission is less than 0.6 lbs. S02/106 Btu heat input. On the other hand older power plants may in many cases be legally emitting up to 6 lbs. S02/106 Btu or more under some State Implementation Plans (SIP). The Clean Air Act requires, however, that in the long run all stationary sources of S02 pollution must abide by the ceiling of 1.2 lbs S02/10 Btu heat input.. Coals with a potential to exceed this limit must, therefore, be considered as high sulfur coals. Such a definition would be unrealistic because many SIP's aim at an emission level of 1.8 to 2.0 lbs. SO2/106 Btu for existing plants and a stricter limit does not appear to be enforceable in the next 5 to 10 years. As a result, coals with an emission potential of greater than 2.0 lbs of S02 per 10 Btu heat input are considered high sulfur coals for the purpose of this investigation. Based on this definition and the 1984 actual consumption of coals by U.S. electric utilities (table 1) only 7 out of the 24 coal producing states could be categorized as low sulfur states. The actual S02 pollution, however, depends on total tonnage of a type of coal as well as the sulfur content of the coal. Table 1 also indicates that only 6 states--Kentucky, Illinois, West Virginia, Ohio, Pennsylvania and Indiana-account for nearly 77 percent of S02 pollution potential in the United States. These 6 states have therefore been chosen for this investigation.

Jan 1, 1986

By Thomas P. Oxford

The impact of recent legislation on Florida phosphate industry operations has been dramatic. The most significant influences are described: the National Environmental Policy Act of 1969; the Federal Water Pollution Control Act Amendments of 1972; and implementation of the Florida Environmental Land and Water Management Act of 1972. Further discussion includes: critical examination of the recently completed EPA Areawide EIS; potential effects of the Resource Conservation and Recovery Act of 1976; the Surface Mining Control and Reclamation Act of 1977; current local and state laws; and summary of studies on radiochemical effects of mining, seepage from gypsum ponds, and dewatering of waste clays.

Jan 1, 1979

By Norman M. Junk

Following the wide-spread acceptance of ANFO as a useful, low cost blasting agent, studies have been made to adequately describe the physical and explosive properties of this material (1). As the quality of the AN blasting prill improved, reliability and sensitivity to initiation were greatly increased and many methods of priming were chosen from the standpoint of economics with little appreciation for the need to initiate so as to obtain the most efficient detonation. Under certain conditions, ANFO could be initiated with primers no more powerful than a No. 8 blasting cap (2). Research on primers for ANFO followed and it was demonstrated that this blasting agent was subject to extreme transient velocities upon initiation with wide variations in energy output depending upon the nature of the primer. For these reasons it was shown that powerful priming was economically justified (3). These studies helped to define the properties of an effective primer and the guides for its efficient use. In the vast surface coal mining industry, technological advances in earth moving equipment were paralleled by the development of larger and larger borehole drills (4). Even though ANM) was the major blasting agent used in this industry, investigations of priming techniques in these larger boreholes was almost non-existant. In 1962, Mr. Cleon Woolsey of Enos Coal Company disclosed to the industry that dramatic improvements in blasting production could be achieved with new priming and boostering methods (5). The research program at the Atlas laboratories was designed to explain these results and extend the study of initiation of ANFO with both high explosives and slurry explosives and to define the principles involved.

Jan 1, 1968

By E. J. Haas, K. A. Rost

"This study sought to identify changes in continuous mining machine (CMM) operators’ risk perception and risk behaviors as a result of adding a proximity detection system (PDS) into their environment. To accomplish this research task, 9 CMM operators from 5 locations were interviewed. Interviews were thematically analyzed for constructs including patterns in risk perception and behavior before and after PDS integration and the process of adapting to the PDS. Operators discussed standing in the red zone less than they did before using the PDS; however, they also discussed other risky decisions they made while learning how to operate their CMM with the PDS technology such as “cheating” the technology and working faster to meet production goals. The process of relearning job tasks with technology and unintended behaviors as a result of that relearning process need to be taken into account when introducing new technology into the mine environment. The study results show an in-depth view of mine workers’ perspectives and how their job tasks and environment could be or are affected when learning how to use new technology that are relevant to companies and mine operators when introducing new technology into the mine environment. INTRODUCTION Established “red zones” can help prevent striking and pinning incidents by providing guidance to continuous mining machine (CMM) operators about where they should stand and not stand while operating a CMM. Although red zones influence operator placement positions, these guidelines are not foolproof safety mechanisms. Depending on the job task and circumstances of the mine environment, a CMM operator may unintentionally or intentionally stand in a red zone. For example, CMM operators may work in close proximity to their CMM for better visual attention cues and the ability to work at a higher rate of production [1-3]. To further enhance protection and prevent collisions between vehicles and mine workers, a proximity detection system (PDS) was developed for the industry. The PDS determines an individual’s position relative to a specific piece of machinery, issues visual and/or audible warnings to the mine worker to change positions, and, if necessary, disables machine motion [4]. The introduction of new technology within other sectors has been identified as a factor that influences work decisions. Specifically, previous research demonstrates that when technology debuts there can be an initial intrinsic risk perceived among users about how the technology will interact with their current environment and behaviors; however, these ambiguities, including the possible risks and benefits, are seldom studied [5]. Some research suggests that the constant presence of technology can disrupt situation awareness and decision-making capabilities by increasing worker responsibilities and worker cognitive demands [6-8]. Further, if workers’ perceived risks both with and without technology are misjudged, unsafe decisions that result in human error and injury may be more likely [9-11]. Although these statements are provided within a broad contextual framework, they support the need to study how technology is perceived among end users in their own environment. Because research about technological impact on worker behaviors has suggested both positive and negative consequences of technology, this issue is worth addressing in the mining industry. Specifically, research has not determined whether CMM operators view their placement choices in the red zone as safe or risky and what effect PDS technology has, if any, on risk perception and subsequent risk behavior."

Jan 1, 2015

By Mei Long, Tawum Juvert Mbah, Jianhua Zhang, Haiwang Ye

There have been many improvements and advancements in the application of neural networks in the mining industry. In this study, two advanced deep learning neural networks called recurrent neural network (RNN) and autoregressive integrated moving average (ARIMA) were implemented in the simulation and prediction of limestone price variation. The RNN uses long shortterm memory layers (LSTM), dropout regularization, activation functions, mean square error (MSE), and the Adam optimizer to simulate the predictions. The LSTM stores previous data over time and uses it in simulating future prices based on defined parameters and algorithms. The ARIMA model is a statistical method that captures different time series based on the level, trend, and seasonality of the data. The auto ARIMA function searches for the best parameters that fit the model. Different layers and parameters are added to the model to simulate the price prediction. The performance of both network models is remarkable in terms of trend variability and factors affecting limestone price. The ARIMA model has an accuracy of 95.7% while RNN has an accuracy of 91.8%. This shows that the ARIMA model outperforms the RNN model. In addition, the time required to train the ARIMA is than that of the RNN. Predicting limestone prices may help both investors and industries in making economical and technical decisions, for example, when to invest, buy, sell, increase, and decrease production.

Jan 6, 2021

By SHANTAE LEE, ELAHEH TALEBI, Frank A. Drews, W. Pratt Rogers

Fatigue in mining operations is a serious issue and a significant contributor to incidents and accidents. While mine operators are using or introducing new technology to monitor operator fatigue, there is little work that focuses on the subjective experience of fatigue and the use of fatigue monitoring technology. To investigate this issue, eight focus groups with a total of 44 operators of heavy haulage equipment working for two mining companies in the Mountain West of the USA participated in 1-h focus groups. The topic of the focus groups was the experience of operator fatigue and issues surrounding fatigue at the workplace. The results of the content analyses suggest that operators are well aware of the signs of fatigue, and that they understand the severity of these signs as well. In addition, they are aware of the effect of fatigue on driving performance and are using a wide range of methods to manage fatigue. Finally, based on participants’ assessment, current fatigue monitoring systems lack face validity and reliability and are perceived as not being effective. The results of this study emphasize the importance of a socio-technical systems perspective in the context of miner health and safety management. Only such a comprehensive perspective can result in improvements that are sustainable.

Jun 17, 2020

By C. V. Deutsch, T. Acorn

Understanding and managing risk is of increasing concern for the mining industry. Although methods exist to model geologic uncertainty based on stochastic modeling techniques and multiple realizations, there are few approaches to manage this geologic uncertainty in pit optimization. Block values can be penalized if the block uncertainty is high, but the goal here is to consider the reserve risk within the pit. This paper presents an approach for pit optimization that considers all realizations simultaneously with a heuristic pit optimizer. The heuristic algorithm maximizes value and also penalizes reserve risk. The inclusion of multiple realizations provides access to the risk or uncertainty in the total pit value. Considering this information permits an active risk management approach that can manage the uncertainty in the reserves within the entire pit.

Jan 1, 2018