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By Kenneth K. Humphreys, F. R. Zachar, A. G. Gilbert

INTRODUCTION by F. R. ZACHAR and A. G. GILBERT Coal producers are not only faced with the problems of mining coal, but must also decide to what extent they can invest capital and what operating and maintenance expense they can afford, after mining, to market their product in sufficient volume and at a reasonable profit. Regardless of whether the operator is contemplating a new operation or merely considering expanding present facilities, market requirements, ability to make a product meeting requirements, probable costs and possible future changes in raw coal or finished product must be considered. In addition, such items as flow sheet, structural designs, storage facilities, etc, must be examined individually and collectively. In estimating preparation costs to meet predetermined market specifications, the operator must calculate the economics of present preparation practices to anticipate the increase to total production which results when the quality of the finished product is increased. The consumers of coal are continually seeking to obtain the best and most adaptable product for their money. Regardless of whether coal is used for coking, industrial requirements, electric power generation, domestic fuel or for other purposes, it will be scrutinized from such standpoints as delivered cost, suitability for utilization in certain equipment, ease of ash disposal, adaptability to material handling system plans and its potential for generating dust problems. Utilities, due to large capacity volume requirements, are generally in a position to select coal that will result in the lowest over-all cost per million Btu. Freight costs, paid by the utility, are important and are given utmost consideration when a coal is under consideration. Steel companies, whether producing or purchasing coking coal, are continually seeking coal that will result in lowering the cost of pig iron production. Since it is usually necessary to clean to lower specific gravities, say 1.40, to turn out a product meeting metallurgical requirements, it follows that a high ash "middling" product is created. These low quality middlings do not command a good price. Therefore, unless the metallurgical coal can command sufficient realization to carry or subsidize the middlings, the operator may be ahead economically to prepare steam coal at a higher specific gravity. While the "unit-train" rate reductions have been helpful to the economy of the coal industry, the establishment of these rates has made mandatory the installation of storage and rapid car loading facilities at mines and plants shipping utility coal (see Chapter 15). A study of the economics

Jan 1, 1968

By E. Shekarchi

A year after the Soviet Union invaded Afghanistan and replaced President Amin with their choice, President Karmal, Afghanistan remained in turmoil. In some respects, the political and economic situation in Afghanistan was no better by the end of 1980 than it was preceding the December 1979 invasion. The Government faced widespread and growing alienation and resistance, virulent factionalism within the ruling party, and an acute shortage of material. The mining sector of the country did not fare better either; the only raw material produced in a significant amount was natural gas, which was exported mainly to the Soviet Union. No statistics on production of other minerals and materials were available by yearend. Most of Afghanistan's gas production was from the Hodja-Gugerdag Field, southeast of Shibarghan. The gas flow from this field had been about 300 million cubic feet per day since 1961. An estimated 230 to 250 million cubic feet per day of Hodja-Gugerdag's production was moved by pipeline across the Amu-Darya River into the Soviet Union. Most of the remainder was transmitted eastward to a 105,000-ton-per-year fertilizer plant and an electric power station built near Mazar-i-Sharif with Soviet assistance. After the Soviet invasion, the second gasfield, Djar-Kuduk, in the Shibarghan area, was brought under production. This field, which will produce about 200 million cubic feet per day, consists of four gas zones in the Jurassic and lower Cretaceous zones between 3,000 and 8.500 feet deep. The gas has a high hydrogen sulfide content, with considerable carbon dioxide, A new treatment plant was built at Djar-Kuduk by Soviet technicians under a turnkey contract at the end of 1980. It is believed that most of the Djar-Kuduk's initial flow will be sent to the Soviet Union.

Jan 1, 1982

By Franklin D. Cooper

The value of nonfuel mineral raw materials produced in the United States in 1978 was $20 billion. In 1979, total value increased to an estimated $24 billion, up 20% from 1978. Of the principal metallic ores produced in 1979, about half showed increased quantitative output and all showed increased value per ton compared with that of 1978. Most nonmetallic commodities showed increases in quantitative output and in average value per ton. Because of its decreasing share of the world market, the domestic mineral industry's concerns were the increasing costs of capital, labor, and energy; withdrawals of public lands from mining; and the increasing cost of environmental regulations that tended to deter or delay investment in the Nation's capacity for producing essential minerals.

Jan 1, 1980

By W. N. Marchant, P. T. Brooks, P. B. Altringer, R. O. Dannenberg

The US Department of the Interior, Bureau of Mines conducted laboratory tests to devise a process for recovering a marketable grade of tungsten from the brine of Searles Lake, Calif. The brine contains only 56 ppm W (70ppm WO3). Using ion exchange resins synthesized by USBM chemists, 98% of the tungsten was extracted from the brine and 92% of the tungsten was recovered as a marketable iron-tungsten concentrate containing 44% tungsten as tungsten trioxide. Although major technical problems have largely been resolved, research is progressing to escalate testing in a process research unit to provide more reliable data for an economic appraisal

Jan 1, 1980

By D. J. Dunn, J. L. Huiatt, T. E. Norman

Corrosion studies in laboratory ball mills and grinding environment simulations produce corrision rates and total metal removal rates much lower than those recorded in operating production ball mills. The corrosion component of ball metal loss in many mills probably represents less than 10% of the total loss, judging from AMAX experience and recent US Bureau of Mines (USBM) tests. Such small absolute losses are consistent with ball metal loss measured in production ball mill marked ball wear tests to determine effects of corrosion and abrasion resisting properties of alloys in operating mills. These indicate that metal hardness and microstructure determine relative metal loss rates of a given situation. The combination of ore characteristics and grinding process dynamics determine metal loss severity. Alloying for corrosion resistance and modification of the milling corrosion environment yield relatively small metal loss reductions. Alloying and heat treatment to produce high hardness and microstructures of high carbon martensite and, for cast irons M7C3 carbides, produces the lowest metal losses in typical wet grinding applications.

Jan 1, 1986

By Jianmin Qin, Raja V. Ramani, Wilson Miola

The number of underground work entities operating under reduced dust standards in U.S. coal mines has been increasing since the start of the decade of the 80s and is currently approaching 10,000. The concern for controlling the quartz levels in airborne respirable dust in coal mine has manifested itself in several improvements in equipment selection and operation, face ventilation practices, and dust control procedures. At the same time, fundamental studies have been initiated on determining the source-sink relationships of the airborne quartz dust. The P-7 method is the prescribed method for the determination of quartz in the respirable airborne dust samples from coal mines. Questions have been raised on the reliability of the P-7 infrared spectrometry method for quartz analysis in powders. No specific method has been defined for quartz determination in bulk samples from the mine. In a recent study on the relationship between quartz in the airborne dust and that in the materials being mined, both infrared (IR) and x-ray diffraction (XRD) methods were used on a suite of samples from several coal mines. These samples encompassed airborne respirable dust samples, airborne total dust samples, the oversize fraction from the respirable samplers, ROM samples, channel samples, and chip samples from the face, roof, and floor materials. In this paper, the sample preparation and analysis procedures for the samples are discussed. The data, analysis results, and comparisons of the P-7 and XRD results are presented. The quartz percent determined for the same sample by the two methods are different. In 85% of the samples analyzed, the quartz percents determined by the XRD method are higher than those obtained by the P-7 method. However, there is a strong linear relationship between the results from the two methods. Further, the XRD method indicates an average of 20 percent more quartz than that from the P-7 method. The reasons for the differences in the results and the need for additional studies are explored.

Jan 1, 1991

By Walter W. Focke, Zola Kwela, Willem van der Merwe, Arao Manhique

"The advantages of the de Wet zirconium process for the manufacture of AZST from zircon sand include: Fewer processing steps; removal of radioactivity by leaching rather than by precipitation; alkali reagent recovery in the form of a sodium silicate solution that is essentially free of radioactivity; fewer waste streams and less waste to discard.Here we report on our efforts at maximizing the alkali recovery in the sodium silicate product stream: Milled zircon, d50 ˜ 9 µm, was fused with caustic soda pearls in open reaction vessels at temperatures between 650°C and 850°C. Fusion times of 1, 2, 4, 24 and 336 hours (with intermittent milling) were investigated.For prolonged fusion times the fusion products approached equilibrium compositions. However, the phases Na2ZrSiO5 and Na4Zr2Si3O12 observed at 850°C did not form at 650°C. Since they do not hydrolyse in water they limit the recovery of alkali. For 2-hour fusions a broad spectrum of non-equilibrium reaction-products, that are rich in sodium silicates, is formed. Optimum process conditions, with respect to NaOH recovery, correspond to a 2:1 stoichiometry and fusing for 2-hour at 850°C. At these conditions the alkali recovery is ca. 78% and the zirconia yield is ca. 57%."

Jan 1, 2003

By M. L. Smith

A new approach to strategic planning, the Life of Business Optimisation System (LOBOS) optimises production systems from the scale of stopes in a single mine to an entire business strategy consisting of multiple mines and products competing for capital and processing capacity. LOBOS has optimised cash flow for a wide variety of operations, including large metalliferous or coal mines and as an aid to high-level strategic business optimisation solution to multi-mine/processing/product complexes. This paper discusses the application of optimisation technology to strategic planning with an emphasis on project evaluation with examples on the application of LOBOS to a variety of recent projects.

Jan 1, 2007

By E. V. Manlapig, David J. Spottiswood

In recent years great advances in the automatic control of flotation plants have been made, mainly due to the development of reliable sensing instruments to monitor process performance and the development of an adequate understanding of system responses to process disturbances. Some of the control strategies used in flotation plants which apply computer control are presented here. These schemes, which involve the control of collector; depressant, frother, and air and pulp level, are analyzed with respect to their control objectives, control variables, and the instrumentation involved. The knowledge gained in understanding these strategies may be applied in the dew and implementation of control system in other concentrators.

Jan 1, 1981

By Gerald G. Griswold, James O. Greenslade, Cherie Tilley, Richard Reseigh

INTRODUCTION The Harrison Western Corporation, a leading Denver based mine contracting and engineering concern, is presently engaged in sinking two 1,006 m (3,300 ft) shafts for the Phillips Uranium Corporation at their Nose Rock Project, approximately 13 miles northeast of the small community of Crownpoint in McKinley County, New Mexico. The Nose Rock Project is the first attempt by the Phillips Uranium Corporation to tap the deep uranium reserves in what has become known as the Grants Mineral Belt. (See Figure 1) Project Description Phillips Uranium Corporation's plan for the large 2700 metric ton per day (2950 tons/day) mining facility calls for a series of deep access and ventilation shafts ranging from 4.27 m (14 ft) to 5.49 m (18 ft) in diameter to approximate depths of 1,006 m (3,300 ft). The initial pair of shafts consists of one production shaft and one ventilation shaft separated by a distance of 91 m (300 ft). The interbedded layers of sedimentary sandstones and shales to be penetrated by the shafts contain several major water producing aquifers, the deepest being the mineralized zone called the Westwater Canyon Member of the Morrison Formation.

Jan 1, 1981

By Anthony Harding

In a world of technology and electronic communication, it is easy to forget what engineers do best with a problem: sitting around a table, exchanging views and ideas with sketches and respecting everyone?s view. This was the approach adopted in the project to arrive at a solution for the cross passage opening sup-port for the Seattle University Link Extension. Schedule and space constraints usually impede concurrent cross passage excavation and tunnel boring machine (TBM) operation. And where the space is constrained, opening support solutions that maximize available cross sections are of great benefit. While there are a number of solutions that minimize space, some of these solutions can require expensive steelwork and extensive drilling and fixing. However, following a detailed round-the-table discussion of the options and constraints, it was identified that a shotcrete shell would not only limit obstruction of the space during installation, but also permit easy installation, particularly around services, and avoid costly steelwork and drilling and fixing.

By A. Cullaj

Several industrial sites suffer from the contamination of soils from heavy metals, which are emitted among others by anthropogenic mining and metallurgical activities. Effective and economic physicochemical technologies for remediation of these sites remain complicated and costly. A new alternative remediation technique is the so-called phytoremediation. This is based on the ability of some plants to accumulate very high concentrations of metals from soils and thus providing the basis for a remediation of the contaminated sites. This technique as an emerging branch of natural biotechnology, has several advantages compared to the sophisticated physicochemical techniques of soil remediation. It is not only environmentally friendly but also its costs are quite low since it is solar driven. Furthermore plants can accumulate metals to such levels that the mineral recovery maybe feasible even in conventional Ni refinery or smelting operations. In this work, thc potential of many plants to accumulate nickel has been investigated in order to identify the species which offer the best phytoremedial potential for nickel contaminated soils in Albania. Field surveys have been made in five nickel-containing sites in order to identify the nickel tolerant species that have spontaneously grown in contaminated soils. Atomic Absorption Spectrometry measurements were carried out on 145 different plants collected. 16 of them were identified as having an hyper ability to accumulate nickel since they contained more than 10 000 mg Ni per kg (DW). Seven taxa are of Alyssum genus and one of Bornmuellera genus of Cruciferae. The highest accumulation of nickel was present in aerial parts of Alyssum murale var. chlorocarpum Hausskn (25 500 mglkg or 2.5%) and Alyssum markgrafli O.E. Schulz (23 700 mg/kg or 2.37%). The seeds germinated are more evidenced at A.m.var. chlorocarpum, about 63%. These plants are suggested as the most promising species to be used for phytoremediation purposes in nickel contaminated soils and phytoextraction of nickel.

Jan 1, 2003

By Mike O'Driscoll

The future for the industrial minerals sector, and of mining in general, is being shaped by a new order of geopolitical and environmental factors. Last year’s foreword focused on an example of the former (U.S. tariff impact). Here, we shall focus on the latter, and in particular on mineral recycling. Mineral recycling is one of the two missions of the mineral industry right now; the other is decarbonization. Get these right and the industry will be more resilient to the challenges to come, plus making much-needed improvements to our environment. But mineral recycling should not be viewed as simply responding to environmental pressures, a checkbox on the corporate portfolio to allay fears and protests of damage to the environment, leading to charges of so-called greenwashing. While mineral recycling will be an important contributor to the circular economy and assisting in climate protection, it will also evolve as an essential alternative source of raw materials, presenting opportunities in mineral recycling project developments, and increased innovation and supply of pertinent processing and sorting technologies. This new era of industrial mineral recycling is already underway and gaining momentum. But it is not plain sailing, mindsets need to be adopted and correct processes employed. Key questions raised include: • How to go about getting involved in this sector? • Whether to vertically integrate? Invest for an in-house business/plant? • How much and how far to invest? What kind of processing/sorting technology is required? • Partner with/acquire an independent recycler? Join forces with same-sector end-use players? • What kind of logistics are involved? Permits for handling/transport? Costs? • Crucially: making grade acceptable, consistent and economic for customers?

Jul 1, 2026

By Diego A. Dávila Novoa

The United States is correctly recognizing copper as a strategic material increasingly tied to artificial intelligence (AI) infrastructure such as data centers, grid modernization, electricvehicle (EV) charging stations, electrification, defense manufacturing, industrial reshoring, energy security and long-cycle economic competitiveness. Recent years have seen rising concern around future copper deficits, accelerating electrification demand, geopolitical fragmentation and the strategic vulnerability associated with concentrated mineral supply chains. As a result, significant volumes of copper cathodes have increasingly flowed into the United States through a combination of Comex positioning, arbitrage opportunities relative to the Shanghai Futures Exchange (SHFE), inventory relocation, tariff anticipation and broader long-term supply-security considerations. However, an important structural distinction is beginning to emerge inside the system — one that remains materially underrecognized across portions of industry, finance, policy, government and institutional planning frameworks. Accumulating copper cathodes inside the United States is not automatically the same as expanding the country’s ability to industrially utilize copper at scale. That distinction matters enormously because the cathodes themselves are not the final product. Their strategic relevance only materializes once the material is transformed into qualified conductive systems capable of supporting real electrical infrastructure deployment across the broader economy. Copper cathodes inside warehouses may improve availability. But availability alone does not automatically create executable electrical infrastructure. The strategic value emerges only once conductive material becomes integrated into functioning industrial systems capable of supporting AI infrastructure; grid infrastructure; utility modernization; electrification; heating, ventilation and air-conditioning (HVAC) systems; EV charging infrastructure; defense manufacturing and broader industrial deployment. This increasingly shifts the discussion away from copper availability alone and toward a broader question of industrial synchronization involving conductive transformation capacity, fabrication capability, electroplating ecosystems, original equipment manufacturer (OEM) qualification, manufacturing scalability, logistics integration, workforce capability, permitting timelines and downstream deployment infrastructure. The challenge emerging inside the United States is therefore not necessarily geological scarcity. Rather, the bottleneck increasingly appears to be migrating downstream into the industrial interfaces required to convert material availability into executable infrastructure deployment, particularly as domestic transformation, fabrication, plating, qualification and deployment ecosystems attempt to scale under infrastructure constraints, long industrial lead times and evolving tariff structures affecting portions of the downstream conductive value chain.

Sep 1, 2026

By D. Morgan Warren, David Hanson, Alice Alex, Tom Meuzelaar, Heather Lawson, Sam J. S. Wright

Dynamic failures, or “bumps,” are a category of ground failure occurring in underground coal mines that involve the sudden expulsion of coal and rock debris into a working area of an active mine. They are an imperative safety concern for the global coal industry. Dynamic failure events have occurred in nearly every coal mining nation of the world, and there have been an estimated greater than 30,000 fatalities as the result of dynamic failure events globally (Bodziony and Lama, 1996; Kidybinski, 2011). Kidybinski (2011) describes them as “the most dangerous natural phenomenon creating a threat to life and health of miners working in hard coal mines.” In the United States, dynamic failures are significantly less common than in many other coal mining countries. However, when they do occur, they result in a proportionately extremely high rate of accidents and fatalities, with more than 60 percent of cases reported to the U.S. Mine Safety and Health Administration (MSHA) resulting in worker injury up to and including death (MSHA, n.d.). The driving mechanisms behind these events are not yet fully understood. Research aimed at optimizing pillar design and mining practices has resulted in a significant decrease in ground control related fatalities including dynamic failure occurrence over the past three decades (Mark, 2024). However, events continue to occur, and new research focused on engineering controls has failed to yield continued, measurable results. It is likely that to produce a further reduction in the rates of dynamic failure accident occurrence, novel research must be pursued. Recent research performed by the National Institute for Occupational Safety and Health (NIOSH), Spokane Mining Research Division (SMRD) has sought to address this need through a focus on the complex interaction between mining induced stressors and risks innate to the host rock mass through improved incorporation of geologic variables into hazard assessment.

Jun 1, 2026

By V. K. Risinggård, M. Sparta, U. Thisted

The Bockman method is regularly used to obtain accurate measurements of the hearth voltage of smelting furnaces. The method uses three measuring leads in order to cancel induction errors using destructive interference when transferring the hearth voltage from the bottom of the furnace to the top of the electrodes. This paper presents an investigation of the Bøckman system's reliability, limitations, and background using finite-element-method simulations. A 3D model of an industrial-scale smelting furnace for Mn-alloy production is developed and used to examine the induction caused by balanced and unbalanced electrical conditions and material distributions.

Aug 3, 2026

By C. Yu, B. Dejun, Y. Weilu, Z. Minglin, K. Htet Oo, Z. Suiyi, L. Xin, Q. Wensheng, K. Hua

Grinding sludge is a gel-like hazardous waste generated in large quantities during metal cutting processes. Conventional calcination and hydrometallurgical treatment of oil-rich grinding sludges emit flue gases and generate insoluble residues. This study proposes CH2Cl2-assisted phase separation under mild conditions to enhance oil removal and metal recovery by overcoming encapsulation effects. Neodymium iron boron grinding sludge, containing 10.4% oil, 8.3% neodymium, 4.5% praseodymium, and 55.8% Fe, was selected as a representative material. Complete dissolution was achieved using a dichloromethane/hydrochloric acid mixed solvent, producing an organic phase enriched with oil, carbon and grease, and an aqueous phase rich in Nd, Pr, and Fe. The aqueous phase was processed to sequentially precipitate a double salt containing 98.58% Nd/Pr and an iron yellow product with 99.97% Fe. This approach provides an effective and economical strategy for the simultaneous recovery of oil and metallic products from grinding sludge, avoiding harsh conditions or costly equipment, offering significant potential for practical on-site industrial applications.

Aug 3, 2026

By C. Gómez, E. Rubio, L. Alfaro, R. Cuba, C. Morante, J. Jarufe

The increasing global demand for metals compels the mining industry to optimise production methods and planning to meet rising needs. However, as mining operations extend deeper, the risks associated with mining-induced seismicity and rockburst hazards become more critical. This paper presents a novel and practical methodology for integrating seismic hazard considerations into mine production planning. By analysing historical seismic and mine production data, the methodology develops actionable guidelines for addressing short-term planning challenges. In contrast to traditional reliance on unwritten miner experience or time-intensive numerical modelling solutions, this approach offers a streamlined and timely framework for decision-making. The proposed framework is applied to a case study of a Peruvian polymetallic mine utilising the sublevel stoping method with backfill. The results demonstrate the methodology's ability to optimise short-term operational decisions, striking a balance between production efficiency and safety standards, and highlighting its potential for broader application in the mining industry.

Aug 3, 2026

By Carrie Smith

Inside a mountain in Idaho Springs, CO, a century-old mine is taking on a second life. The Edgar Experimental Mine (EEM), once a key producer of valuable ore, now trains engineers and soon may host quantum experiments that could reshape computing. Edgar began as a working underground operation where miners extracted ore from narrow veins deep in the rock. What once produced silver, lead and gold now generates something less visible. In 1921, the Colorado School of Mines (CSM) transformed the mine into an educational facility for mining students, preserving the underground workings as a hands-on training environment. More than a century later, the same tunnels built for extraction are supporting a different kind of industry. Instead of chasing mineral deposits, researchers are using the mine’s depth to study quantum systems, particle physics and train engineering students. Today, a growing network of research laboratories operate inside Edgar. Among them, a new quantum facility is taking shape, where the Colorado Underground Research Institute (CURIE) will turn the mine into a hub for high-scale physics research. The development of the new underground facilities would not have been possible without the hard work of the CSM’s mining engineering department. Over the course of a year, the department worked tirelessly to create a suitable space for future experiments. “The mining engineering department provided the mining expertise, planning and student labor necessary to excavate and prepare the underground spaces required for the quantum laboratory,” said Lee Fronapfel, mine manager of the Edgar Experimental Mine. That work included drill-and-blast excavation, ground support installation, shotcrete application, concrete floor placement, ventilation systems and electrical infrastructure, among other necessary adjustments. “To support quantum research activities, larger underground excavations were created in areas of the mine with the greatest depth of rock cover,” Fronapfel said. “These locations were selected to help minimize environmental interference and provide the stable underground conditions required for sensitive quantum experiments.” Unusual coordination between physicists and mining personnel occurred. Two fields that rarely intersect worked together to create an underground environment capable of tackling some of science’s most complex questions. Now, these departments collaborate closely to ensure all work is carried out effectively. “Because the laboratories are located in relatively isolated areas of the mine, vibration and noise impacts are generally limited,” said Fronapfel. “However, occasional coordination is required to manage activities that could affect sensitive experiments. This is handled through direct communication between mine personnel and quantum researchers.”

Jun 1, 2026

By M. A. Dippenaar, J. L. van Rooy, R. Bush, M. Maoyi, A. Lotriet

Effective management of unsaturated fluid flow in open-pit excavations is critical, as mining disturbances like blasting can enhance fracture connectivity, permeability, and water infiltration, thereby compromising slope stability. This study evaluates infrared thermography as a non-invasive tool for detecting seepage zones in a fractured rock highwall at an open-pit quarry in South Africa. Field-scale measurements and photogrammetry data are used to gain a better understanding of unsaturated flow behaviour in fractured rock masses. Passive infrared thermography established baseline thermal anomalies associated with natural groundwater seepage, revealing distinct cooler surface patterns in highly fractured domains that aligned with geotechnical mapping. Active infrared thermography using controlled injection of cold water into the high wall enabled real-time thermal monitoring, confirming preferential channelling along lithological contacts. The findings demonstrate that infrared thermography is a powerful and reliable technique for remotely evaluating areas susceptible to seepage on high walls, highlighting its promise for improving hydrogeological risk assessment in mining operations.

Aug 3, 2026