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By L. Blain

In practice, geochemical analyses can be grouped in two broad categories according to their aim. Those that seek to determine the exact chemical composition of geological materials fall under the heading of assays, whereas applied geochemistry concerns itself with the detection of anomaly contrasts. Recent trends have blurred the distinction between both approaches for many users, as methods that were traditionally used for assays are being adopted in applied geochemistry and assays make increasing use of instrumental techniques. Nevertheless. it is important to keep a clear distinction between the two types of analyses because it has immediate practical consequences, cost is the most obvious, as well as fundamental implications. In the broadest terms, the goal of geochemistry is to strike an optimal balance between throughput and accuracy, at the lowest reasonable cost, while assays strive for accuracy. Traditionally, complete silicate analysis has been the concern of assayers whereas exploration geochemists have been more interested in base metal analyses where acid extractions of the elements, without dissolution of the silicate matrix, has been the norm. This kind of distinction is less realistic now, especially with the growth in lithogeochemical studies, and some overlap in methodology is unavoidable. However, where such overlaps occur the distinction remains in the emphasis of the work. A commonly used example is that although HF acid preparations are used by both, the emphasis in applied geochemistry is on sample throughput and batch analysis, whereas assayers are more concerned with the range of elements to be determined (Thompson and Walsh, 1983).

Jan 1, 1993

By T. Reed Scollon

Major interrelated factors to be considered in assessing the impact of air pollution control regulations on coal are: (I) the fuel and fuel-related limitations of such regulations; (2) the rate of adoption and areal scope of the regulations; and (3) the availability of fuels and fuel-burning equipment to meet the requirements. A growing number of regulations contain provisions limiting the emissions of sulfur oxides or the sulfur content of fuels or both. With few exceptions, these limitations have not yet become fully effective in those areas which have already adopted regulations, and pertinent details of future regulations or legislation for most other areas are unknown at this time. Sufficient information is not avail- able to determine the availability of low-sulfur fuels at various demand and price levels, and large-scale commercial feasibility of sulfur-oxides removal processes and equipment is believed to be some years away. Accordingly, with the many uncertainties and unknowns, it is possible at best to make only a rough assessment of the impact of such regulations or legislation on coal.

Jan 1, 1969

By J. B. Hanlon

In order to protect coal mine owners, operators, and lending institutions from potential environmental liabilities, responsible parties must maintain a thorough understanding of the environmental disposition of the property they control, and the ramifications of impending laws and regulations. The best way to accomplish this is to periodically conduct a Phase I Environmental Audit. The systematic approach of an audit will reveal areas of DOD compliance with SMCRA and EPA regulations which the coal owner and/or operator will be able to use to correct deficiencies and prevent the occurrence of conditions which could lead to permit block, fines, and ultimately reduced productivity.

Jan 1, 1995

By Gregory M. Rumbaugh, Todd R. Kostecki, Christopher Mark

From 2015 to 2021, five massive pillar collapses occurred at four underground stone mines in the eastern USA. These events resulted in powerful airblasts that damaged mine infrastructure and mobile equipment, seriously injured miners, and disrupted underground travelways. Each of these pillar collapses propagated through the overlying strata, causing a subsidence sinkhole on the surface. Pillar collapses are particularly hazardous for miners because they can occur with little warning and can affect miners that are far from the pillar collapse area. The following case studies show that certain factors may increase the likelihood of a pillar collapse. For instance, each of the 5 events involved at least 12 benched pillars with width-to-height ratios (w/h) of 0.8 or less. This study elaborates on these factors and proposes a framework to assist mine operators where they identify similar hazards.

Jul 24, 2023

By Halter L. Gould

Since the turn of the century there has been a marked increase in population, industrial and economic growth, and in energy requirements in the United States. During this time our energy needs have been met largely by natural gas and petroleum, but as our reserves of these materials are depleted, we are going to depend more and more on our large reserves of coal. The mining of coal for electrical power production has increased at a rapid rate during the past decade. Over half the coal produced in the United States in 1971 came from mines utilizing surface mining operations (Paone, et al, 1974). Surface mining is expected to increase as the rising cost of oil places more demand on coal for energy. About 57 percent of the coal reserves in the United States lie in the area west of the 100th meridian. About one-quarter of this can be mined by current surface methods. This would involve the disturbance of approximately 1.5 million acres (600,000 hectares). By the year 2000, projections indicate disturbance of about 200,000 acres, or 300 square miles, in the West. Mined areas receiving more than 250 mm of annual precipitation can usually be revegetated without irrigation if the spoils are properly shaped, the surface layer consists of suitable plant growth media, and proven techniques in rehabilitating disturbed rangeland are applied. Areas receiving less than 250 mm of annual rainfall or with high evapotranspiration rates pose a more difficult problem. Revegetation of these areas can probably be accomplished only with major inputs of water and good management (National Academy of Science, 1974).

Jan 1, 1978

By W. R. Reed, G. J. Joy, B. Kendall, A. Bailey

"Testing of the roof bolter canopy air curtain (CAC) designed by the U.S. National Institute for Occupational Safety and Health (NIOSH) has gone through many iterations, demonstrating successful dust control performance under controlled laboratory conditions. J.H. Fletcher & Co., an original equipment manufacturer of mining equipment, further developed the concept by incorporating it into the design of its roof bolting machines. In the present work, laboratory testing was conducted, showing dust control efficiencies ranging from 17.2 to 24.5 percent. Subsequent computational fluid dynamics (CFD) analysis revealed limitations in the design, and a potential improvement was analyzed and recommended. As a result, a new CAC design is being developed, incorporating the results of the testing and CFD analysis.IntroductionExposure to respirable coal mine dust can cause coal workers’ pneumo-coniosis (CWP), also known as black lung. If silica is present in the dust, the miner may develop silicosis in addition to CWP. CWP and silicosis are occupational respiratory diseases that are ultimately fatal and have no cure. The only method of prevention is to eliminate exposure to respirable coal mine dust and crystalline silica, or quartz. The occupational exposure limit on a Mining Research Establishment (MRE) basis for respirable coal mine dust had been 2 mg/m3 during each shift that a miner is exposed in the active workings of the mine or in mine facilities. Under recently enacted legislation, this standard was changed in August 2016 to 1.5 mg/m3 for a full working shift (The Office of the Federal Register, 30 CFR 70.100, 2015). When respirable quartz is present, the mine must maintain its average concentration at or below 0.1 mg/m3. If the mine exceeds the 0.1 mg/m3 respirable quartz dust concentration, then the applicable respirable dust standard is reduced, calculated as 10 divided by the percentage of quartz present (The Office of the Federal Register, 30 CFR 70.101, 2015).The sources of exposure to respirable coal mine dust for roof bolting occupations include infrequent maintenance and cleaning of the vacuum dust collection system and operating the bolter downwind — in the return air — of the continuous miner (Good-man and Organiscak, 2003). Recent studies have demonstrated that vacu-um dust collection systems are effective in capturing bolter-generated dust if maintained and operated correctly and if proper face ventilation techniques are used. However, most expo-sure to respirable coal mine dust for a roof bolter occurs when the roof bolter machine is operated downwind of the continuous miner (Potts, Reed and Colinet, 2011; Colinet, Reed and Potts, 2013). Because of this higher exposure downwind of the continuous miner, the roof bolter is often limited to working downwind of the miner only once during a production shift."

Jan 1, 2017

By T. Marcher, C. Mathiesen, M. Allende, S. Bauer

"A unique pumped hydro storage facility using the ocean as a lower reservoir, combined with solar PV to create consistent, clean power will be presented: the Espejo de Tarapacá Project is comprised of a 300 MW seawater pumped storage hydroelectric plant using the Pacific Ocean as its lower reservoir and an existing natural concavity at the desert as its upper reservoir. The plant site is located in Chile’s northern coast 90 km south of Iquique. The site is characterized by a rocky shoreline and about 600 m of flat terrain moving inland, with an abundance of rock outcrops, after which there is a steep 700 m cliff. The power house and all waterways will be underground. The main focus is to present the rocks being expected in the underground works. As one of the actual most tectonically active regions of the world the seismic activity is particularly relevant and will be outlined in the presentation. INTRODUCTION Valhalla Energy is an independent Chilean-owned power development company. It focuses on the development, ownership and operation of renewable power projects. Valhalla was founded in 2011 with the goal of developing Chile’s natural renewable energy resources and strategically diversifies the country’s energy matrix away from an overdependence on imported fossil fuels. Valhalla began developing pumped storage hydro projects to provide scalable, clean, competitive, and reliable electricity by combining Chile’s superior solar resources with the country’s unique and extensive coastline suitable for storage.The capacity for renewable energy supply is driven by two distinct and unique natural characteristics found in northern Chile: (1) the abundant and reliable solar irradiation in the Atacama Desert and (2) a coastal site that benefits from a steep cliff and a natural concavity both within a relatively small land mass (see Figure 1). There are several potential sites in the northern part of the country that can be developed. The “Espejo de Tarapacá Project” is the first one to be built and subject of the present paper."

Jan 1, 2016

By McCarthy. Richard E.

The prime movers of the Centralia Project, the surface coal mine and the power plant, private utilities are very aware of public attitudes. They have established and maintain the reputation for leadership in public service and are genuinely concerned that this project initiate the pro-grams and design the hardware to answer the question :What will be the impact of the mine and the plant on the physical environment, i.e., the air, soil and the water." So in the beginning almost as soon as the decision had been made to go ahead with the project, officials of the two private utilities, Washington Water Power and Pacific Power & Light went on record and publicly stated time and again that the overall approach of the Operators would be to do all that was reasonably possible to safeguard the environment. This attitude became part of the thinking of the project planners, part of the design of the power plant and part of the plan for the surface mine. The coal to be mined is from the Skookumchuck formation. The formation is Late Eocene and is made up of poorly consolidated marine and non-marine deposits. The major overburden removal equipment is a bucket-wheel excavator -conveyor system and a 56 yard dragline. Mining of the coal will be done with truck and shovel. The coal is processed, washed and crushed to 1 ¼ " for delivery to the power plant. The muddy water created by the washing process is chemically treated and the solids removed by a thickener-vacuum filter system.

Jan 1, 1971

By Edward O. Reinbold

The paper presents the results of a study which involved collection and analysis of airborne pollutant concentration data in two producing underground room and pillar metal mines which use diesel powered equipment in the area near the face. The results include the concentrations of CO2, CO, NO, NO2 and respirable particulate matter measured with the latest portable instruments, and the carbon and hydrogen contents of the particulate matter samples determined by combusting them in a Elemental Analyzer. The carbon and hydrogen contents are used to estimate the amount of diesel particulate matter in the mine ambient air. The short term grab sample concentration data, although not suitable for determining compliance with ACGIH Threshold Limit Values (TLVs), are related to the TLVs so that they may be compared conveniently. Lognormal frequency distributions and the arithmetic mean of the concentration measurement data are used to compare different mine situations. Conclusions are drawn as to which pollutants are most important to control under actual mine production conditions.

Jan 1, 1979

By F. Rudloff, C. Karageorgos, J. Moyo, I. Boadi, M. Struble, B. Lumsden

Over it’s more than 100-year history, the Kennecott operation has often been at the forefront of innovation; driven by the demands of the lower grade ore-body and the higher costs of operating in the US where wages are generally higher and regulation more restrictive. One way of reducing operating costs in c/lb is to increase the lbs produced at minimal cost. Despite the relatively coarse grind at Kennecott - about 30% >150μm, approximately 20% of the Cu lost to tail is liberated chalcopyrite in the <20μm fraction, and about 30%-40% in the <37μm fraction. In 2020 Kennecott undertook a detailed plant scale test of the magnetic aggregation technology to increase copper recovery by reducing fine copper losses. A paired statistical plant test of magnetic conditioning on one rougher line showed a 1.12% increase in Cu recovery to 97% statistical confidence. The next challenge, unforeseen at the start of the project, was the fabrication and transportation to site of the equipment for the three remaining rougher rows, during the severe supply-chain constraints of the Covid pandemic in 2021. This resulted in delays and unforeseen costs as world-wide transportation became chaotic, particularly transportation via west coast USA. Nevertheless, the project was completed and commissioned, with only minor delays and cost increases, due to a flexible approach to overcoming the hurdles encountered.

Feb 1, 2023

By Owens S. Roberts

The drive selected for any piece of machinery must adequately satisfy the application requirements both during the starting interval and at running conditions, All loading possibilities of the drive must be known and allowances made for any adverse limiting conditions such as extreme cold, or perhaps an intermittent excessive loading situation etc. In general, the drive must be selected to provide the required operating characteristics with maximum reliability and at minimum cost. Simplicity of overall design is always an advantage and care must be exercised to insure that systems incorporating unnecessary complicated parts are not indiscriminantly provided. Important non-technical considerations such as equipment avail-ability (on an overseas project) as well as standardization details also play a role in the drive selection process. Additionally, an assessment of the potential capabilities of the personnel that will have to maintain the equipment can have some influence on the final choice. Several types of prime movers are available but this article will restrict itself to the use of induction motors operating from an available alternating current power source. Many drive arrangements are possible, the most common being the direct coupled single motor arrangement. It is sometimes desirable to use more than one motor per machine, but these designs are usually more

Jan 1, 1971

By Zhiyuan Shen, Dan Zhao

The abstract discusses the importance of reliable mine monitoring systems for preventing accidents. It focuses on diagnosing ventilation system failures caused by roadway faults that alter airflow resistance. The paper proposes using an improved Support Vector Machine (SVM) method to identify the fault location based on changes in air volume detected by wind speed sensors. The approach involves building a sensitivity 0-1 matrix and establishing a roadway fault scope library. The improved SVM method is tested on the Daming coal mine, demonstrating its effectiveness in diagnosing fault locations, reducing training time, and improving accuracy compared to traditional SVM.

Apr 5, 2022

By I. Chatterjee

The application of microwaves has a demonstrated potential for the ultimate removal of water from fine coal. The principle of microwave drying of fine coal is based on the selective absorption of microwaves by water. Coal is a poor absorber of microwaves. As a result, water can be removed from fine coal by selectively heating water molecules. One of the difficult problems drilling microwave heating is the exact determination of temperature in the core of the materials. The electromagnetic energy absorption in coal/water mixtures during microwave drying is controlled by several factors including the dielectric properties of the constituents. In this paper the dielectric properties of various ranks of coal are presented as a function of frequency and moisture content. The measured dielectric data are incorporated into electromagnetic and thermal models of coal which predict the energy absorption and temperature distribution during microwave heating.

Jan 1, 1990

By Jamal Rostami, Omid Frough, Wei Hu

Characterizing the abrasiveness of soil/rock and the allowable wear of hard-facing products in various conditions is a critical factor in selection of the best material for certain applications related to drilling and excavation in mining and construction industries. The Soil Abrasion Index test machine at Colorado School of Mines (CSM) is one of the recently developed unique systems capable of testing soil/crushed rock abrasion under various conditions, such as dry, wet, and saturated settings. It is also capable of testing the performance of various types of hard-facing materials in a given geo-material. This paper studies the wear properties of different hard-facing materials in various crushed rocks from a surface mining operation in the iron range region of the USA. The hard-facing materials include regular and hardened steels and six different specialized hard facings, based on chromium carbide. The soil/rock include a standard sand and two rock samples from the surface mine. Fourteen abrasion tests were conducted, where the weight loss of each hard-facing material was measured over timespans up to 1 h of testing. The results show the distinct performance differences between the steels with 17 HRC and 43 HRC hardness and the hard-facing products for this application. The results show the possibility to evaluate the abrasiveness of different rocks at a mine or construction site and the performance of various hard facings in similar working conditions. This is a practical solution for selection of the cutting tool or reinforcement of bucket lips and truck beds for comparison of relative wear life between different wear-resistant materials.

By Frank Agyemang, Zainab Nasrullah, Richard LaDouceur, Mehran Saddat

To sustain the circular economy, defence applications, and other renewable technologies, recycling rare earth elements (REEs) and other critical elements from their secondary resources is important. This cause has resulted in rigorous research and development for viable extraction and separation of REEs. Previously, Sm-Co recycling has been done with technologies, which fall under the categories of pyrometallurgy, physical separation, and hydrometallurgy. All these methods have limitations associated with energy, cost, and environment. Reportedly, the chemical leaching technology has successfully recovered and separated Sm-Co. Still, it has limitations associated with slow mass transfer and leaching kinetics, and there is a need to intensify the process to make it time efficient. This approach has also adversely impacted the environment by an extensive use of toxic, corrosive, non-selective, and expensive reagents. In this research study, chemical leaching of Sm-Co was performed using this new class of solvents, Deep Eutectic Solvents (DESs), which fall under the category of ion metallurgy. Four different DESs were used, proven to be green, non-toxic, biodegradable, cheap, and selective for cobalt over samarium by 82% leaching conversion. To improve the slow mass transfer and leaching time, this new technology of resonant vibratory mixing (RVM) was also tested. RVM intensifies mixing by establishing near instantaneous, low energy mixing conditions through resonance. It has been shown to improve the adsorption kinetics and was tested for the leaching kinetics. Four combinations of DESs were prepared, which are made up of two quaternary salts: Choline Chloride and Tetra Butyl Ammonium Chloride, and three organic compounds: Oxalic Acid, Urea, and Ethylene Glycol. These combinations were used for chemical leaching of Sm-Co with leaching factors of time, temperature, and type of DESs. After leaching, the samples were tested with and without resonant vibratory mixing with conditions of time, intensity (%), and type of DESs. Samples were analysed with Induced Coupled Plasma - Optical Spectroscopy (ICP - OES). Future work will involve a life-cycle assessment to assess the RVM technology with other conventional mixers, and an extensive study of DES properties to improve selective leaching.

Feb 1, 2025

By David J. Boron

The United States has the largest total (364 billion metric tons) and recoverable (182 billion metric tons) coal reserves in the world.1 However, progressive coal utilization in this country has been hampered by environmental constraints, such as restrictions on sulfur dioxide, nitrogen oxides, and particulate emissions. New technologies are being pursued both to appease these environmental concerns and improve economic performance and process efficiency. These technologies, however, have not reached the level of effectiveness required for optimum operation. If more stringent emission standards are imposed, it is likely that the coal industry, and the industrial and utility sectors will look increasingly toward the successful development of new and advanced coal cleaning technologies in order to continue and promote the use of coal in this country. The EPA New Source Performance Standards In 1979, the Environmental Protection Agency in response to the amendments to the Clean Air Act of 1977 issued new source performance standards (NSPS) for utility and industrial boilers. The NSPS set emission standards for sulfur dioxide, nitrogen oxides, and particulates affecting boilers of 250 MM Btu per hour heat input or &apos;greater that started construction after September 1978. Plants starting construction or in operation before September 1978 remained subject to the provisions of the regulations promulgated in 1971, i.e., SO2 emissions of 1.2 15/MM Btu. The NSPS for SO2 emissions provides a sliding scale for SO2 reduction depending on the sulfur content of the run-of-mine coal, with an upper limit of 1.2 lb of SO2 per million Btu and a minimum emission level based on 70% SO2 removal. Table 1 summarizes the EPA NSPS for SO2 emission standards.

Jan 1, 1983

By Fred Delabbio, Sverker Hartwig

As openpit copper operations transition from surface mines to underground, the speed of underground infrastructure construction prior to production is critical for maximizing the value of the project. Typically, the preferred underground bulk mining method is block caving. In preparation for future underground projects, Rio Tinto made the strategic decision to invest in a step-change program that would develop system solutions to reduce the construction time of block caves. The program focused on improving safety and doubling or more the construction speed of both vertical shafts and horizontal infrastructure compared to existing drill-and-blast rates. After an extensive selection process, Rio Tinto selected the Atlas Copco mobile miner machine as one of the concepts to proceed with for construction of horizontal infrastructure for access and footprint. In addition to un-derground drilling and hauling equipment, Atlas Copco?s Robbins mobile miner concept (a previous attempt at horizontal mechanical excavation) completed trials at Mount Isa, Pasminco and Taisei. Rio Tinto selected the new Atlas Copco mobile miner machine concept for a number of reasons including the use of proven technology from the three previous mobile miner machines and other commercial products, as well as the ability to install complete ground support typical with high rock stress conditions at approximately 1,500 to 2,000 m (4,900 to 6,500 ft) depth. Atlas Copco, with support from Rowa, the Swiss company that specializes in back up systems for tunnel boring machines (TBM), is advancing the detail design of the access version of a tunneling system on behalf of Rio Tinto. Because of the different requirements between an excavation system for access tunnels and that for tunnels on the footprint, two different versions of the mobile miner machine technology were envisioned. The access and the footprint versions of the Atlas Copco mobile miner machine share a majority of key technologies and systems. Therefore, it was possible to conduct a performance conformation test using a full-scale version of the access machine that would also mitigate the technical risks for the footprint version. To alleviate confusion, this article focuses on the access version of the Atlas

Jul 1, 2010

By Theodore H. Eyde

The porphyry copper province of the southwestern United States and northern Mexico, is the largest copper producing region in the world. Most of the deposits occur in Arizona which now produces over 54% of the newly mined copper in the United" States. As the many recent discoveries are brought into production, Arizona&apos;s share of the nation&apos;s copper production will increase. The term "porphyry copper" as used in this paper includes all deposits of generally low grade disseminated copper mineralization amenable to bulk mining techniques. Therefore, copper deposits such as Pima-Mission, Twin Buttes, and Vekol where the copper mineralization occurs principally in the intruded rocks will be considered as "porphyry copper" deposits. Most of the deposits have been discovered since World War II, consequently, the southwest, and particularly southern Arizona is perhaps the most intensively explored area for copper deposits on earth. Most of the major natural resource companies in the United States and Canada maintain exploration offices in southern Arizona. To illustrate the success of exploration efforts, the location of porphyry copper deposits either known or producing prior to World War II are shown on figure 1 and the deposits discovered since World War II which are either in production or in the exploration and development stage are shown on figure 2.

Jan 1, 1973

By N. Agron-Olshina

The application of the QEM*SEM image acquisition and analysis system to the measurement of the mineral matter in coal and the materials in fly ash is described. A new sample mounting technique was developed using iodinated epoxy to provide a backscattered electron contrast between the coal, the mounting medium and the mineral matter. Several comprehensive and detailed species identification programs for silicate minerals and materials were developed to analyse the 1000 count x-ray spectra used for the measurements. Case studies are presented to demonstrate the capabilities of the new technique to distinguish different coals and fly ashes by their mineral and material composition rather than by conventional chemical analysis. Applications of the new technique are aimed at demonstrating that composition and size distributions obtained from OEM*SEM measurements can be used: 1. to characterize coal with respect to combustion problems in power stations, 2. to characterize coal for fine coal cleaning, 3. to characterize fly ashes in relation to problems such as erosion in combustion systems and the ease of precipitability in dust collection facilities, 4. to refine the classification systems used in marketing coal for pulverized fuel firing and fly ashes as a component of cement and building materials.

Jan 1, 1992

By Jianbo Hu, Gang Han, Tao Zheng, Junfeng Jiang, Rui Su, Qihua Zhao

The rock quality designation (RQD) is a commonly used index for the classification and evaluation of rock mass quality and is widely adopted in mining and geological engineering. The traditional method of obtaining RQD still requires manual measurement of core length and calculation of RQD, which is inefficient. To address this problem, we propose a framework for drilling core image segmentation and RQD estimation from digital images of cores in core boxes based on the deep learning algorithm. The proposed framework is generated by combining the Mask Region-Based Convolutional Neural Networks (Mask R-CNN) instance segmentation algorithm, the U-Shaped Convolutional Neural Networks (U-Net) semantic segmentation algorithm, and the image processing functions of the Open Source Computer Vision Library (OpenCV). To demonstrate the accuracy of the proposed method, seven boreholes in the Xiushuihe vanadium-titanium magnetite mine, located in the Sichuan Province, China, were used as the case study. According to the comparison of the manual measurements and calculations of the cores taken from seven boreholes used to conduct this study, the framework can record the length of the drill cores and calculate RQD within an average error rate of 3.42%, while it saves about 85% of the working time. The results illustrate that the proposed framework enhances the efficiency of RQD calculation while satisfying the engineering requirements.

Jul 31, 2023