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By Emily Sarver, Cigdem Keles, Jonathan Gonzalez

The study re-examines respirable coal mine dust samples using scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). It finds that SEM tends to overpredict the abundance of dust from rock strata and underpredict coal content, possibly due to coal-mineral microagglomerates (MAGs). The findings suggest that MAGs could be valuable in improving dust controls in mines.

Feb 10, 2022

By W. R. Reed, D. E. Pollock, T. W. Beck, J. A. Organiscak, J. D. Potts

In underground continuous mining operations, ventilation, water sprays and machine-mounted flooded-bed scrubbers are the primary means of controlling respirable dust exposures at the working face. Changes in mining arrangements — such as face ventilation configuration, orientation of crosscuts mined in relation to the section ventilation and equipment operator positioning — can have impacts on the ability of dust controls to reduce occupational respirable dust exposures. This study reports and analyzes dust concentrations measured by the Pittsburgh Mining Research Division for remotecontrolled continuous mining machine operators as well as haulage operators at 10 U.S. underground mines. The results of these respirable dust surveys show that continuous miner exposures varied little with depth of cut but are significantly higher with exhaust ventilation. Haulage operators experienced elevated concentrations with blowing face ventilation. Elevated dust concentrations were observed for both continuous miner operators and haulage operators when working in crosscuts driven into or counter to the section airflow. Individual cuts are highlighted to demonstrate instances of minimal and excessive dust exposures attributable to particular mining configurations. These findings form the basis for recommendations for lowering face worker respirable dust exposures.

Jan 1, 2016

By L. Alan Weakly

The Powder River Basin of northeastern Wyoming and southcentral Montana contains the largest strip minable reserve of compliance coal (0.27 kg or 0.6 or less Ibs of sulfur per million Btu) in the United States. In mining parlance, it is the mother lode. Wyoming's portion of the Basin is called the Southern Powder River Basin (SPRB). It has been the nation's top coal producer for the past nine years. And based on 1997 production statistics and estimated strippable compliance coal reserves, Wyoming should remain the nation's top producer for the next 51 plus years. In August 1994, ME featured 10 articles that covered all aspects of coal production in the SPRB. In this issue, five authors update the 1994 articles and provide a pre- diction of what the Basin will look like at the turn of the century. In addition to this article, the titles and authors of the other five articles include: ? "Geology of Wyoming's Powder River Basin coal field," by Gary B. Glass and Robert M. Lyman. ? "Coal quality challenges in the Powder River Basin," by Sharon Roness, Richard A. Turpin and Robert A. Young. ? "Markets for Southern Powder River Basin coal," by , Patti J. Best and Patrick W. Wright. ? "Evolution of mining equipment in the Powder River Basin," by Kenneth R. Miller and James L. Long. ? "Hauling coal into the 21st century," by Dave Willis and Will Cunningham.

Jan 1, 1998

By Orris C. Herfindahl

Every few years we are treated to a battle over trade policy when the Reciprocal Trade Agreements Act comes up for consideration. In 1962 it is especially appropriate to consider the problem of mineral import -policy and the closely related problem of general import policy, for this year's struggle is different from those of the past in two ways. First, proposals have been made which are a substantial departure from past trade agreements legislation, and second, the formation and growth of the Europe Economic is Community may have an important bearing on the kind of legislation that is adopted. But this anticipates what is to come later. My task is to examine the problem of mineral import policy, although we shall find soon enough that general trade policy must be considered in order to get an indication of what is in store for minerals.

Jan 1, 1962

By Feng Junfa, Du Feng, Li Huamin, Syd S. Peng

"The Ordos coal field is located in the northern midwestern part of China (Fig. 1). Since the mid- 1980s, it has been developed into one of the major coal fields in the world, producing approximately 833 Mt (918 million st) of raw coal in 2013. There were once more than 400 coal mines operating in the region. However, due to the combination of market conditions and implementation of government consolidation policies, the number of coal mines operating in recent years has been reduced considerably, with increasing output.The surface of the Ordos coal field is covered with loess and alluvium layers of varying thicknesses. In many areas, their combined thickness may amount to as much as 100 m (328 ft) underlain by thin bedrock. Many loess and alluvium are aquifers receiving water from rainfalls. There are also gullies of varying depths crossing the coal field. Figure 2 is a typical stratigraphic column highlighting the coal seams and roof and floor rocks of interest.In conjunction with the development of highproductivity coal mines, numerous ground control instrumentation tests have been conducted in the operating longwall panels. Analyses of the results of those tests offer the opportunity to understand the effect of wide-ranging mining and geological factors on the overburden movement. For this reason, trips were made to coal mines of interest to interview mine management and collect their unpublished internal research reports on ground control instrumentation. In addition, literature searches on published thesis/dissertations and papers in the professional journals were performed. Finally, data from a total of 95 fully mechanized longwall panels were collected. The instrumentation involved primarily the monitoring of hydraulic pressures of longwall shields, from which the first roof weighting and first roof caving interval and periodic roof weighting and periodic roof weighting interval were identified and determined. Some panels also included measurements of roofto- floor convergence at the face, roof strata bed separation, longwall face sloughage and the height of caving and fractured zones in the overburden. Those 95 panels were located in 20 coal mines (Fig. 1) congregated along both sides of the Wulunmulun River with the following mining and geological conditions. All together those 20 mines produced more than 224 Mt (246 million st) in 2013, accounting for approximately 27 percent of the total coal production in the Ordos coal field:1. Period of mining: 1991-2013.2. Mining methods: All panels employed the one slice, full-seam natural-caving longwall mining method like those practiced in the United States. All panels were developed with a twoentry system with a single-row of chain pillars measuring 20- x 20-m (65.6- x 98.4-ft) wide.3. Coal seams (Fig. 3): Coal in Ordos coal field is high-quality steam coal, that is very low in sulfur, potassium and ash, but high in Btu. Data were collected in panels mined in a total of 10 seams with 82 panels in four seams and the remaining 13 panels in six seams. The first six seams (1-2, 2-2, 3-1, 3-2, 4-2, 5-2) were mined by the Shenhua Coal Group (the world’s largest coal company) and the #4-2, 5-2, 6R, 62, and 62R seams were mined by both the Shenhua and Yitai Coal groups. In each coal group, the sequence of mining was in descending order. For example, in Shenhua Group, the top seam 1-2 was mined first, followed by the 2-2, 3-1, 3-2, and 4-2 seam in that descending order. In Fig. 3, the top-down sequence of coal seams is listed from left to right in each coal mine group. All seams were near horizontal with dip angles less than 3°."

Jan 1, 2014

By Jodi Banta

Thanks to strong industry support and longstanding partnerships, the University of Arizona has provided extensive pre-college mining education and outreach for more than a decade. These efforts to promote mining-related degree programs and the wide variety of indemand career opportunities reach thousands of middle and high school students and hundreds of teachers every year. The School of Mining Engineering & Mineral Resources is constantly looking at ways to help students overcome barriers into degree programs. But competition among degree programs for talent is fierce, and outreach has not made a big enough difference in the number of students pursuing mining engineering degrees. With workforce shortages threatening to undermine the industry, more is needed. The Bureau of Labor Statistics estimates 500 new mining engineering jobs each year, and according to a study by Deloitte (2023) nearly 50 percent of skilled engineers will reach retirement age in the next decade. At the same time, the 14 accredited mining or mineral engineering degree programs in the United States are producing fewer than 200 graduates annually (Society of Mining Professors and Society for Mining, Metallurgy & Exploration, 2021). To better understand mining’s competitive position, the School of Mining Engineering & Mineral Resources conducted a comprehensive study to determine (1) how prospective college students, parents and educators perceive the industry, related careers and the mining engineering degree, (2) factors affecting students’ choices of degrees and career plans and (3) the roles parents and educators play and how they influence students. This article is the first of two installments to discuss the results. This installment focuses on what students, parents and educators think about mining and where they get those impressions, as well as the role parents and educators play in influencing students’ choices of careers and degrees. The second installment, scheduled for publication in a later issue of Mining Engineering, looks at what students are seeking in their degrees and careers, and how mining compares with other degrees and industries.

Sep 1, 2025

By Frank A. Jerabek

Problems of mine backfilling and fill material deposited underground, the characteristics and relationship between the deposited fill material and overlying ground, and the practical applications and limitations of hydraulic backfilling as ground support are discussed. A great variety of materials ranging from coal washery refuse to concentrator tailings is used as hydraulic fill. Some materials will solidify and cement; others will resemble quicksand, Hydraulic fill as ground support is more efficient in inclined mine openings than in horizontal mine openings, where it cannot be placed tightly to the back. This and other deficiencies of hydraulic backfilling led to the development of pneumatic stowing. Research work in hydraulic backfilling at the Pennsylvania State University is also discussed. This research work includes the investigation of segregation in the discharged fill slurry, the quantity of solids escaping in the drain liquid, the relationship of escaping solids to slurry concentration and discharge rate, and the compressibility of fine fill material.

Jan 1, 1965

By Nord L. Gale

The discovery of important new ore deposits of lead, zinc, copper and silver in 1955 in Southeastern Missouri has resulted in the development of a thriving mineral industry known as the "New Lead Belt" or "Viburnum Trend", to distinguish it from the older lead producing areas to the East. This region has recently become the world's largest lead producing district with production in 1970 reaching 432,576 tons or 74.4% of the entire United States lead mine production. The area is heavily forested with rolling hills dotted with numerous clear running streams in the Clark National Forest of the Missouri Ozarks. The location is within 70 miles of St. Louis, Missouri and has a natural abundance of water resources which provide an important recreational area for fishing, hunting, camping and other outdoor activities. Until this recent development, the area was sparsely populated and industrialization was almost unknown. The infusion of $150 million in mining capital has brought about a dramatic change in the economic structure of the area and will almost surely be accompanied by changes in its environmental picture. In an effort to maintain this bountiful national resource and to evaluate the changes occurring in surface water quality and aquatic life forms present, an inter- disciplinary research program at the University of Missouri has been undertaken with the support of the National Science Foundation. Research has been carried out to determine background values, establish natural baselines, and to evaluate the extent and causes of changes in streams effected by mine water discharges and wastewater from ore milling operations. The unique topography of the "New Lead Belt" area allows the channelization of milling and smelter wastes to separate stream systems (Figure No. 1) thus allowing measurements of the pollutional effects on an individual basis.

Jan 1, 1973

By E. Siami-Irdemoosa, S. R. Dindarloo

"Discrete event simulation is a stochastic mathematical modeling tool with applications in queuing systems. Many mining operations, both surface and underground, can be simulated in the context of queuing theory , for example open pit loading and haulage operation, underground level and vertical transportation, and mineral processing circuits. A computer simulation model of the operation is an invaluable tool to study both the system’s dynamics and conducting sensitivity analysis on different effective elements on system performance. In this paper, merits of discrete event simulation in decision making in mining engineering is discussed. Moreover, a stochastic simulation framework for selection and sizing of shovels and dump trucks in surface mining is presented to elaborate one example for applicability of the method in mining operations. INTRODUCTION Mathematical modeling is a valuable tool in design, optimization, and decision making in both surface and underground mining operations. Several researchers have tried to study different aspects of mining operations using a wide range of mathematical techniques such as linear programming[1], analytical hierarchy process [2], non-linear programming[3], genetic algorithms[4-5] ,mixed integer programming [6], machine repair model[7], queuing theory [8], and conventional spreadsheet calculations based on experience and engineering judgments. There are different uncertainties in typical mining operations (e.g. material loading and haulage, drilling, and blasting). For example, in a truck-shovel operation, different governing activities such as loading, haulage, and dumping cycles are stochastic variables. Moreover, analytical modeling of a large truck-shovel operation is very complicated. Thus, application of analytical and/or deterministic techniques cannot guarantee a solution for different problems that are encountered in daily mining operations. Discrete-event system simulation (DES) is a modeling method for such time discrete and probabilistic phenomena [9]. DES has been employed by different researchers in mining engineering through available software and languages such as GPSS, SIMAN- ARENA, and SLAM [10-14]. Most of the studies so far, tried to evaluate some “what-if” scenarios, to understand the possible effects of changing different input variables on overall mine economics. For instance, Baffi and Ataeepur (1996) used Arena to simulate a truck-shovel operation [10]. Also, Sturgul has conducted extensive studies in the application of DES in the mining engineering field [15- 17]. A very good background review of application of this technique in the industry can be found in [15-16]. Previous studies have shown that, different approaches including deterministic, stochastic, and experimental methodologies result in considerable differences in outputs [18]. These techniques lead to different solutions, regardless of the quality of technique/software itself or knowledge of the modeling team. Hence, the first step is to develop a comprehensive simulation framework to obtain nearly the same optimal results for the same input variables, regardless of the employed technique."

Jan 1, 2016

By Ravindra M. Chhatre

Uranium associated with phosphate deposits has been the subject of numerous investigations (1-8). In the land-pebble phosphate deposits of central Florida, uranium is found in the phosphate matrix (ore) and in the leached zone between the over-burden and matrix (1). Between 0.01 to 0.02 percent uranium is found in the leached zone, which consists of apatite and aluminum phosphate minerals (crandallite, wavellite, millisite) (Z). The primary phosphate mineral in the matrix is apatite, and the 0.005 to 0.01 percent uranium typically found in the matrix is associated with this mineral (1). It is generally believed that uranium substitutes for calcium in the apatite structure (3-5). Clay and quartz phases associated with phosphate deposits contain little uranium (1, 6), and no descrete uranium minerals have been detected in these deposits (4). A typical phosphate matrix consists of quartz, slimes (-150 mesh material) and recoverable phosphate. When the matrix is beneficiated, partition of uranium and radium takes place (9, 10). Although considerable data exists on how uranium is distributed in the phosphate deposits, no systematic study has recently been reported on the distribution of uranium during phosphate rock beneficiation. The purpose of this study was to determine how uranium is distributed in the various strata which comprise the overall land-pebble phosphate deposits, as well as how the uranium is redistributed during beneficiation of phosphate matrix. To obtain this information studies were carried out on matrix samples obtained from three different mines in central Florida. Using pilot-plant scale beneficiation, an analysis was performed on how uranium in the matrix is distributed among the pebble fractions, flotation concentrates, flotation tails, and slimes. The uranium level profile for an active mining area was also obtained. Also, since thousands of acres of slime ponds may someday become a source of both phosphate and uranium, a depth versus uranium content profile was determined for an inactive slime pond.

Jan 1, 1978

By Serdar Aktaş, Burcu Nilgün Çetiner

According to critical statistical studies, antimony is one of the rarest elements in the world, and global resources could be exhausted by 2050. In light of these observations, its extraction will be costly due to poor-quality ore, deep mining, remote locations, and high energy consumption. In the present study, an alkaline leaching process was carried out on stibnite concentrate to evaluate the effect of reaction parameters on the percentage of antimony extraction. The leaching efficiencies of different sulfur and hydroxide sources were studied and compared to one another to create a better understanding of the reaction process. Kinetic models were investigated to identify the reaction pathway and calculate the activation energy. The activation energy of the stibnite dissolution was assessed as 19.13 kJ/mol using a two-dimensional diffusion-reaction model. The value of activation energy indicates the quantity of energy necessary for a reaction to proceed. As expected, potassium hydroxide leaching was significantly more successful than was sodium hydroxide; however, in terms of economics, the use of sodium hydroxide was found to be more cost-efficient. Interestingly, this finding indicated that caustic leaching is still the most effective method for stibnite extraction.

Jul 23, 2020

By M. S. Celik, H. Du, J. D. Miller, F. Cheng, O. Ozdemir

"In this paper, recent progress with respect to the flotation chemistry of soluble salt minerals is reviewed, and some of the more relevant issues including the hydration states of ions, the interfacial phenomena of salt surfaces and the flotation behavior of selected soluble salts are discussed. Due to the high solubility, the flotation of most soluble salts has to be carried out in their saturated brines. Anecdotal evidence has suggested that the hydration states of the ions have significant influence on the physicochemical properties of the solutions, the surface charge and wetting characteristics of the minerals, the collector adsorption states and, further, the flotation behavior of the soluble salts. In this regard, reviewing past research findings, efforts are made to establish a correlation between the ion hydration states with the flotation behavior of the soluble salts. Further, advances in understanding the significance of colloid adsorption involved in the soluble salt flotation process are addressed, and future research efforts to understand the soluble salt flotation chemistry are suggested.IntroductionSoluble salt minerals are essential raw materials for the production of a variety of commodities, fertilizers, potassium hydroxide, soda ash, magnesium compounds and other chemicals. These soluble mineral resources can be processed using flotation technology and, currently, more than 80% percent of the world’s potash is produced by the selective flotation of KCl crystals (sylvite) from other salt crystals, predominately NaCl (halite) and other more complex salts (Searls, 1990). Despite the successful application of flotation technology in the potash industry, the mechanisms for collector adsorption on soluble salts have not yet been fully understood and, therefore, have been of considerable interest to flotation researchers for many decades."

Jan 1, 2015

By Paul B. Valenti

The Nevada Moly Operation of Anaconda Minerals Co., (a molybdenum/copper ore body) was initiated in 1978, with a contract to Bechtel Civil and Minerals Inc. for construction of a mining and milling facility near Tonopah, NV. Ground was broken on the concentrator portion of the project in August 1979$ with a multi-phased startup of the mill beginning in June 1981. Processing design tonnage of 20 000 t/d (22,000 STPD) was reached in early 1982. Major pitfalls of rapid design and implementation of engineering, construction, and startup are considered. The operation of the concentrator including SAG milling, ball milling, bulk rougher flotation, copper/moly separation, moly regrinding and cleaning, thickening, and product loadout are discussed.

Jan 1, 1983

By H. Shafick Hanna

The major problems are identified the high phosphorus content and the fine dissemination or encapsulation of mineral impurities, in, ,the iron bearing minerals, A process which combined extreme fine grinding techniques with magnetizing roasting or flotation separation methods, is suggested. By these methods concentrates assaying 60-61 percent Fe exceeding the widely accepted upper limit of 56 percent Fe set for these ores, were produced with 75-90 percent iron recovery. Moreover it was shown that the phosphorus content of these concentrates could be reduced from 0.25 to 0.03 percent phosphorus by acid leaching. A brief discussion on production costs based on current and future developments in iron ore processing is given.

Jan 1, 1980

By Clinton Birch

The multiple-criteria decision analysis is a technique that helps to find an optimal solution by evaluating conflicting criteria. In this study, an approach to perform multiple-criteria decision analysis for cut-off grade optimization, which considers the diverse stakeholder groups prevalent in the mining industry, is presented. The optimization model developed in this approach links the resource block model to the financial model, enabling the process to either maximize profit, net present value, revenue to the State, or extend the mine's life. To identify the optimal cut-off grade in each case, the Excel Solver function is utilized. Although it has limitations, the Solver function can still be modified to handle models with thousands of block values for determining input variables based on the target value. Following stakeholder engagement and dialogue, a single weighted average cut-off grade can then be determined. This approach is demonstrated for nine South African Witwatersrand gold mines.

Jun 25, 2023

By K. Darcovich

The wettabilities of agglomerates made from coals of several different ranks were measured by the adhesion technique. Oil levels from 0 to 10% by weight were used. As was expected, it was found that higher-rank coals are more easily oil-wetted and that the surface properties of the agglomerates correlate with agglomeration recovery and ash removal data.

Jan 1, 1992

By Martin H. Stanczyk

The Organic Act of 1910 established the Bureau of Mines and gave it authority and responsibility for conducting research on separation, recovery, and recycling of waste products and scrap generated by the mineral and metals industries and the consuming public.(1)1 It was apparent to our Nation's leaders even then that mineral resources, once mined, are irreplaceable and that the development of methods for recycling the values contained in wastes would be required to solve the problem of even¬tual scarcity, Estimates of the increase in per capita consumption of mineral resources in this country indicate that the consumption of metals, minerals, and fossil fuels by 1980 will be double that consumed in 1970 (2). The United States can expect to meet its future mineral needs in three basic ways: the first is through increased production of primary raw minerals; second by increasing imports from foreign sources; and third by recycling secondary materials and metals that were formerly discarded as waste. Rather than consider these

Jan 1, 1972

By Quanjun Liu, Rongping Lin, Rongdong Deng

Arsenic contamination significantly affects the quality of copper concentrates, presenting challenges during smelting processes. Considering that covellite and enargite have similar surface properties, they are difficult to separate by flotation, resulting in copper concentrates with excessive levels of arsenic. To address this issue, this study systematically investigated the flotation separation of covellite and enargite in microflotation and bench-scale flotation tests using calcium lignosulfonate as a depressant, with the results indicating that calcium lignosulfonate can be used to separate covellite and enargite because it enables the separation of arsenic-bearing copper minerals into high- and low-arsenic (As 0.57%) copper concentrates. According to contact angle and adsorption tests, scanning electron microscopy–energy dispersive spectroscopy, and X-ray photoelectron spectroscopy, the differential adsorption of calcium lignosulfonate onto covellite and enargite is the primary reason for their distinct flotation behaviors in the presence of calcium lignosulfonate. The selective depressive effect of calcium lignosulfonate provides a novel approach for improving the flotation separation of arsenic-bearing minerals from copper sulfide minerals.

Feb 28, 2024

By B. Pesic

The recovery of silver and gallium from flue dust with acidified thiourea solutions was examined. The studied parameters were temperature, particle size, thiourea concentration, acid concentration, and the presence of oxidants. The study of the extraction of these two metals was undertaken in sulfuric acid medium. Silver dissolution was dependent on all examined parameters, whereas gallium extraction was only dependent on the initial acid concentration. The experimental results suggest a new very efficient method for recovery of both silver and gallium. Almost complete recovery of silver and gallium can be accomplished within 90 minutes. A technological scheme for recovery of both metals is also proposed.

Jan 1, 1986

By H. Dho

The role of sodium silicate in the anionic flotation of a Florida phosphate ore was investigated using laboratory continuous flotation tests, frothability tests and SEM observations. In the absence of sodium silicate, Ca++ promoted the unwanted activation of quartz by forming calcium bearing precipitates. The addition of sodium silicate enhanced the flotation efficiency through: (1) the removal of impurity minerals and calcium-bearing. precipitates from quartz surfaces by dispersion, (2) drier and more persistent froths stabilized by oily droplets containing calcium silicate precipitates, and (3) higher specific flotation rates of phosphate relative to quartz, leading to faster flotation rates and increased selectivity of separation.

Jan 1, 1990