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By Benjamin Grunauer, Anthony Iannacchione, Taylor DaCanal

"In Pennsylvania’s rich mining history, various forms of room-and-pillar mining have been in use for over 150 years. Longwall mining, introduced in the late 1960s, occupies only the last 60 of those 150 years and now represents the dominant method of extracting coal in the Pittsburgh coalbed. The introduction of longwall mining allowed larger quantities of coal to be extracted in safer and more efficient manners than room-and-pillar mining. However, the associated formation of subsidence basins have elevated both the number and intensity of watersource and surface structure impacts. When these first longwall panels were mined the factors responsible for these impacts were poorly understood and regulations were focused only on surface structures. Today, with over 600 panels mined under a wide range of conditions, these factors are known and regulations have developed to help mitigate water supply and surface structure impacts.The cause and severity of surface effects are thought to be dependent on multiple factors, including the location within the subsidence basin, overburden, panel width, and orientation of the panel. The changing characteristics of over 600 longwall panels mined in the last 60 years are analyzed to determine factors important in subsidence related surface impacts. This study compares the location of the surface impacts with the longwall panel size, overburden, and maximum predicted vertical subsidence. The data shows that changing these characteristics are impacting surface features in a significant manner as measured by the number of company liable reported effects.INTRODUCTIONLongwall mining has occurred in Pennsylvania for over 60 years, and at the current mining rates, longwall mining is expected to continue in the Pennsylvania Pittsburgh Coalbed until the reserves are exhausted. Figure 1 shows all mining that has occurred in the Pittsburgh Coalbed, as well as the area that is left to mine. It is predicted that there are 40 years left of longwall mining on the Pittsburgh Coalbed, under the assumption that 50% of the total 280,000 acres will be mined at the current rate of 3500 acres/year."

Jan 1, 2019

By M. C. Fuerstenau

A number of interesting and. important phenomena were revealed during a study of the response of beryl to sulfonate flotation (1). Perhaps the most important observation is the effect of various cations on flotation response. Experiments showed that in the vicinity of pH = 3. 0, about three ppm Fe.+++ increased recovery of leached beryl from about 60 to 100 per cent, whereas about four ppm Ca++ reduced the recovery from 60 to 2 per cent. With the exception of ferric iron, all of the other cations investigated reduced flotation recoveries drastically at this pH. As postulated in the paper "Sulfonate Flotation of Beryl", (1) even with low concentrations of polyvalent cations and sulfonate (on the order of one ppm), cation¬ sulfonates are precipitated immediately in solution. That is, blueish-white clouds .were noted to form after given additions of salts to. known solutions of sulfonate. Furthermore, it was also shown that one-hundred-fold more ferric iron than necessary to form the precipitated cloud had to be added to effect complete flotation. In other words, some form of solid ferric sulfonate was found to function as the collector in these systems. The form of the compound was suggested to be Fe (RSC3)2OH and that bonding to the surface occurs through the hydrogen of the hydroxyl. As the form of this compound was shown to be dependent on the extent of hydrolysis of ferric iron, it is to be expected that ferric iron will be unique in some pH region. Further, if the presence of hydroxyl in the neutral precipitated compound is of primary importance, then other cations should function similarly but at different values of pH, since they will hydrolyze at different concentrations of hydroxyl ion. To determine whether the premise of hydrolysis is correct, the study was extended to quartz systems lit the presence of various cations at various values of pH.

Jan 1, 1964

By RIINA SALMIMIES, ANTTI HAKKINEN, PAULA VEHMAANPERA

Better understanding of the mechanisms and kinetics of dissolution can benefit several industrial processes. For example, iron can be leached from clays, which can be further used as a raw material in the ceramic industry. Another important application is the regeneration of ceramic filter media, which are used in the dewatering of iron ores. Dissolution of iron oxides in mixtures of acids is fairly uncommon and a less well-understood phenomenon, but it can result in a more efficient process. This work also shows that the determination of dissolution mechanisms and kinetics is not straightforward in different acid systems.

By Isabel F. Barton, Matthew J. Gabriel, CARSON ROBERTS, JOHN LYONS-BARAL, LEON DUPLESSIS, Mark D. Barton

Geometallurgical assessment of orebodies in the mining industry typically relies on bench-scale or lab-based characterization techniques. In this study, we investigate drone- and tripod-based field hyperspectral imaging as a potential addition to the geometallurgy toolkit in multiple applications. This pilot study tests hyperspectral imaging for largescale mineral mapping in and around the active Lisbon Valley copper mine, including natural exposures, previously producing U-V mines, highwalls, dumps, and leaching sites. Tests include different (supervised and unsupervised) mineral data classification methods, varying mineral spectral reference libraries, comparison with ground-truth geological and spectroscopic mapping and sampling, and integration with LiDAR data. The results show that hyperspectral scans can produce spatially registered maps of the distribution of different spectrally active mineral types over dumps, highwalls, leach pads, and natural outcrops. Clays, other phyllosilicates, carbonates, and sulfates showed up particularly well. The sensor was also able to distinguish dry from lixiviant-saturated areas and map different clay types on the leach pads, and shows promise for differentiating types and health of vegetation. These results suggest that hyperspectral imaging, if coupled with robust ground-truthing, can be a useful complement to existing geometallurgical techniques in the mining industry, such as geological mapping, blast hole sampling and automated mineralogy identifications, and handheld spectrometry. In particular, hyperspectral imaging has promise for mapping the distribution of acid-consuming minerals; mapping the distribution of swelling, sliming, and heap-blinding clays; and pinpointing problem areas on heap leach pad surfaces.

Feb 10, 2021

By I. H. Warren

The high temperature lubricant molybdenite, MoS2, is usually produced by a complex sequence of processes involving mineral dressing of molybdenite concentrates followed by leaching with hydrofluoric acid to remove abrasive impurities such as silica (1). Many attempts have been made, mostly by techniques involving, direct fusion of molybdenum compounds with sulphur, to produce synthetic molybdenite. However, apart from some experiments of geochemical interest (2) in which aqueous solutions of sodium sulphomolybdate, Nat MoS4, were decomposed under pressure at temperatures between 300°C and 700°C, no attempts to produce the mineral by hydrometallurgical procedures have been reported. Since molybdenite is nominally a compound of tetravalent molybdenum with sulphur, and the most common state of molybdenum is +6, production of molybdenite is likely to involve reduction and sulphidization. The present study, therefore, describes the reduction, with hydrogen and carbon monoxide, of molybdenum in the hexavalent state in alkaline aqueous solutions containing sulphide ion. In these

Jan 1, 1972

By Miguel Reyes, Bruce Whisner, Joseph Bickson, Lincan Yan, David Yantek, Justin Srednicki, Nicholas Damiano, Eric Bauer

Built-in-place (BIP) refuge alternatives (RAs) are designed to provide a secure space for miners who cannot escape during a mine emergency. Heat and humidity buildup within RAs may expose miners to physiological hazards such as heat stress. To minimize the risk of heat stress, Title 30 Code of Federal Regulations (CFR), or 30 CFR, mandates a maximum allowable apparent temperature (AT) for an occupied RA of 35 °C (95 °F). The National Institute for Occupational Safety and Health (NIOSH) has conducted extensive research on the thermal environment of occupied RAs intended for use in underground coal mines. NIOSH research has demonstrated that a fully occupied BIP RA can exceed the AT limit by more than 5.6 °C (10 °F) in mines with elevated mine strata and air temperatures. In this circumstance, an RA cooling system could provide a solution. This paper provides an overview of test methodology and findings as well as guidance on improving the performance of a cryogenic air system prototype by optimizing the flow rate, increasing the tank storage capacity, and improving the efficiency of the heat exchanger of the cryogenic system. This may enable BIP RAs to meet the 35 °C (95 °F) AT limit in mines with elevated temperatures. The information in this paper is useful for RA manufacturers and mines that may choose to implement a cryogenic air system as a heat mitigation strategy.

By B. Mishra, Q. Shi

Numerical simulations have been used to investigate roof fall in the past decades. Comparing to the continuum based methods, the discrete element method has been well recognized for its excellent performance in simulating large strain problems and fracturing processes in the rock mass. However, the discrete element method has its limitations. When simulating a large-scale problem, a large number of particles are required, which consumes significant computational resources. In the present study, a 3D numerical model coupled with the finite-difference method (FDM) and the discreteelement method (DEM) was created to simulate the laminated roof failure in an eastern coal mine in the US. In the FDM-DEM coupled model, the laminated roof of the entry is represented by an assembly of bonded particles using PFC3D. The laminated roof is simulated by adding parallel discontinuities. The discontinuities are given certain stiffness and strength in the model. The ribs, floor, and far-field surrounding rock are represented by continuum zones using FLAC3D. The strength of the discontinuities is varied sequentially and the fracturing of the laminated roof was analyzed with respect to entry advance. The results showed that the laminated roof fractures along the discontinuities while an intact roof fractures in a dome shape. Increasing the strength of discontinuity could enlarge the tensile zone inside the laminated roof and hence change the crack distribution. In addition, the crack quantity in the laminated roof behind the advancing face decreases with the increment of discontinuity strength while this trend is not occurring ahead of the advancing face. The simulation demonstrated that coupled method using PFC3D/FLAC3D can reproduce the laminated roof failure in underground coal mines.

Mar 2, 2022

By Ali Soofastaei

Mining operations are increasingly data-rich yet decisionconstrained. Fragmented systems, variability in geology and operations, and sustainability obligations create multiobjective trade-offs that classic analytics cannot reconcile at operational tempo. This paper proposes an end-to-end framework that fuses digital transformation practices (governed data platform, semantic layer, feature store, and MLOps) with generative AI (retrieval-augmented generation, tool-use, and agentic workflows) and decision intelligence (simulation/digital twins and multi-objective optimization). We formalize sustainability-aware objectives, define a practical stack and governance controls, and demonstrate how an AI “decision copilot” can surface options, quantify trade-offs, and document rationale. Two figures illustrate a production-grade architecture and a Pareto frontier for cost–emissions trade-offs; two tables operationalize decision-domain mapping and a transformation maturity rubric. The approach is product- and company-agnostic.

Feb 22, 2026

By David A. Newman

The Geomechanics Classification (Bieniawski, 1979) was modified for entry and roof support design in underground room-and-pillar coal mines. Adjustment multipliers were introduced to incorporate the influence of strata weatherability, high horizontal stresses, and the roof support reinforcement factor into the existing classification system. Sixty-two case histories of both standing and fallen mine roof were collected from two mines in the northern Appalachian coalfield. Twenty-seven engineering and geologic parameters were recorded for each case. A partial correlation analysis was carried out on the cases to establish which parameters have a significant impact upon the supported stand-up time of coal mine roof. Survival analysis, a statistical technique used in medical research to assess the effect of a drug or treatment on a patient's life expectancy, was conducted together with stepwise multiple regression to derive values for the adjustment multipliers. A practical example is included to illustrate the application of the modified Geomechanics Classification to underground coal mine design.

Jan 1, 1985

By Fredy A. Elorrieta Agramonte, Gabriel von Rickenbach, Roberto Luis Fonseca, David Córdova Rojas, Rolando Romero, Rico Brändle

The mine’s economic life is dynamic by nature. Some factors that create this scenario are the need to recognize new exploitation areas, the evolution of the mineral prices and the development of new technologies to access them. The dynamics of mining development, especially in the underground environment, changes significantly as the stages unfold. In many cases the final solution differs greatly with the initial. The frequent presence of new conditions and factors often cause the mine to develop in a quasi-permanent transition stage, which could be characterized by the generation of dynamic micro-seismic events that could cause rockburst damage in some specific areas. Although they may be infrequent, these dynamic events can have an important adverse impact on mine safety and causes serious losses. Also, changes in the production schedule during exploitation could be a big issue if the problem is not effectively addressed. When the transition of the mine to an active micro-seismic environment begins as an unforeseen scenario, it is frequent to use static ground support systems as they are readily available. Traditionally, the support systems used are reinforced shotcrete with a middle layer of Welded Standard Wire Mesh (WSWM) and Chain Link Standard Wire Mesh (CSWM) of reduced gauges, i.e. wires less or equal than 4 mm in diameter. Although, this support system is used to control static instability problems, there is no good reference of its energy absorption capacity under dynamic load conditions, creating uncertainty in the effectiveness of controlling rockburst events. These support systems are analyzed at the present paper, testing the reinforced shotcrete layer with 4 mm diameter of WSWM and CSWN under dynamic load. Additionally, the influence of the use of high tensile strength steel wire in the meshes (HSWM) compared to the previous ones, is analyzed to assess the scope in controlling rockburst events and keeping the safety of underground environment.

Apr 26, 2022

By Sidney M. Cohen

[Portland cement is a product made from a combination of limestone and argillaceous material which would supply the necessary amounts f calcium, silica, alumina and iron to form cementious compounds when fired at high temperatures. The resulting mixture, usually around 80% limestone and 20% argillaceous, is ground nine (80% -200 mesh), blended and then fired1 (2600-2700°F) to produce a cement clinker from which the final cement product is produced by grinding. The argillaceous component can be shale, clay, slate or other sources of the individual components of silica, alumina and iron. This paper deals with a case where a clay component was under consideration. The planned Plant site was to be located at a well defined limestone deposit. When it came to the argillaceous component, the nearest uniform deposit of clay was over 50 miles away and would require purchase of land or clay from the owner plus the daily delivery costs to the plant site. This situation made the plant site economically questionable. It was decided that a local clay deposit, which was available at the plant site but was orginally not considered due to lack of chemical uniformity and its high free silica content, would be reconsidered.]

Jan 1, 1983

By Andrzej M. Wala

A knowledge of the friction factor (K-factor) is necessary in planning and designing mine ventilation systems for least cost and highest effectiveness. The friction factor used must be accurate and reliable for correct estimation of airway resistances. At present, the friction factors are determined by using tables of published values. These values were established principally for metal-mine openings having small effective areas. This presents a problem to the ventilation design engineer whose responsibilities center around the design of effective ventilation systems for large room-and- pillar mechanized underground coal mines. Friction factors selected from these tables could be excessively conservative for large scale room-and- pillar operations. With only limited data on the K-factor (which are considerably site dependent) for Kentucky's coal mines and for all the above mentioned reasons, it was concluded that there is a need for field investigations to determine these values in-situ for existing mining conditions in Kentucky. The author describe the study carried out in ten coal mines located in eastern and western Kentucky and present the results of the investigation in both tabular and graphical form.

Jan 1, 1991

By J. H. Canterford

To date, large-scale solution mining has received little attention in Australia, although the potential of this technique has not gone unnoticed. The possibility of long-term damage to the local environment has also been recognized. Because no two orebodies are the same, it is clear that the application of solution mining techniques and the assessment of environ- mental damage will be somewhat different for different orebodies, even though the general principles will be the same. At present the most significant copper solution mining operation in Australia is at the Mammoth (Gun- powder) Mine in northern Queensland. This mine currently produces more than 3 000 t of cement copper a year.1

Jan 1, 1981

By W. H. Renison

This paper will discuss the operation and maintenance of Molycorp's Quests Mine ore conveyor system. The 1.2 m wide, steel cable-reinforced conveyor belts are capable of transporting 1089 kt/h of ore over a belt line distance of 3124 m with a vertical rise of 518 m. A portion of the conveyor runs in a 2057 m long underground decline on a 10° slope. Six 448 kW motors power the main 1.2 m wide belts.

Jan 1, 1984

By Jr. Lownie

Estimates of the cost of producing any commodity generally fall into several classes depending upon the motives and needs of the estimator. There are estimates intended to show how low costs might be with favorable conditions if everything goes well. At the other extreme, there are estimates which show how high costs might be if troubles develop. The estimates in this paper for the cost of producing direct reduced iron (DRI) are accompanied by discussion to point out how the final figures may be adjusted in either a promotional or a conservative direction. Because we do not have a specific process and a particular set of conditions in mind when discussing this subject today, this paper deals with the general situation, with considerable attention to how the estimates can be made more specific once one knows the particulars of a given situation.

Jan 1, 1978

By K. D. Luxbacher, E. C. Jong

Perfluoromethylcyclohexane (PMCH), a member of the perfluorocarbon tracer group of compounds, has been shown to be a viable supplement to the widely used tracer gas sulfur hexafluoride (SF6). This viability stems from the fact that PMCH can be used concurrently with SF6 while maintaining adequate chromatographic separation and comparable sensitivity during analysis. However, the release of PMCH in an underground mine ventilation system is challenging due to its physical characteristics. While SF6 exists as a gas at room temperature and pressure and can be accurately released by a variety of means, PMCH exists as a volatile liquid at room temperature and pressure, preventing it from being deployed in a similar manner. One method to release PMCH is to use a permeation plug passive release vessel (PPRV), which allows for the controlled release of the gas. This paper presents the results of a study evaluating various preparation techniques, plug thicknesses and plug materials of an aluminumvessel PMCH release source, so that a source appropriate for the mine scale may be developed.

Jan 1, 2015

By D. P. Caplice

On behalf of the Ontario Water Resources Commission, I would like to express my sincere appreciation to your Institute for presenting us with this opportunity to outline the regulatory control programme as it relates to the mining industry in the Province of Ontario. In Canada, and particularly in Ontario, we are blessed with an abundance of natural resources. Fresh water in the form of lakes and rivers covers nearly 17 per cent of the area of the Province. (Total area of the Province of Ontario is 412,582 square miles.) The mining industry, which had its beginning in the early 1800's with a small iron ore plant, has progressed with the major discoveries of nickel and copper in 1883, silver in 1903, gold in 1908, iron in 1939 and uranium in 1953, to the point where, in 1966, almost one billion dollars in mineral wealth was mined in Ontario. Water, in spite of its great abundance and with due respects that it may become a natural resource worthy of export in the foreseeable future, has become increasingly precious in Ontario, particularly in the more urban areas in the southern part of the Province.

Jan 1, 1968

By J. D. McKay

The Bureau of Mines devised a column flotation technique using either fine or coarse bubbles and compared it with conventional flotation on a Montana chromite ore. On deslimed ore, fine-bubble column flotation produced a 44.7-pct-Cr203-grade rougher concentrate with 87-pct recovery, compared with 43.8- and 43.5-pct-Cr203-grade rougher concentrates with 85- and 77-pct recovery for coarse-bubble column flotation and conventional flotation, respectively. On undeslimed ore, coarse-and fine-bubble column flotation produced rougher concentrates containing approximately 41.5-pct-Cr203 with 95-pct recovery, exceeding conventional flotation which produced 35.6-pct-Cr203-grade concentrates with 87-pct recovery.

Jan 1, 1985

By Homer E. Harris

As a result of the enactment of the Federal. Coal Mine Health and Safety Act of 1969 1, the Department of Health, Education, and Welfare (HEW) has been carrying out research in the "field of coal mine health". The National Institute (formerly Bureau) for Occupational Safety and Health (NIOSH) was designated the agency within HEW to be responsible for such research activities. One of the early programs sponsored by NIOSH was undertaken by Eastern Associated Coal Corp., with the Harvard University School of Public Health participating as a subcontractor to Eastern. This program on Coal Mine Respiratory Protective Devices, which started on June 30, 1970, had five major objectives as follows: a. to determine current status of respirator usage with respect to duration and frequency, types. and maintenance b. to determine acceptability ( and reasons therefor) of currently used units c. to determine protection factors provided by respirators worn by working miners d. to make recommendations on ways to improve existing units, or on research needed to develop new types of respiratory protective devices for coal miners e. to provide recommendations to mine management on more effective use of respiratory protective devices

Jan 1, 1973

By Jung-Joo Kim, Jong-Uk Kim, Turab H. Jafri, Han-Kyu Yoo

"INTRODUCTION Steel sets such as H-type and lattice girders are often installed in the tunnels before the hardening of shotcrete to ensure the stability of conventional tunnels in soft ground conditions. In practice, while designing the tunnels with the help of numerical analysis, steel sets are generally considered only as temporary support elements. Only a few studies propose the direct application of composite support in the tunnel design, based on large-scale experiments and numerical analysis. In order to assess the structural performance of the composite support consisting of shotcrete and steel sets, large-scale experiments were performed on two types of arch-shaped specimens by applying the combined effects of axial forces and bending moments. Based on the experimental results, numerical analysis was performed to assess the application of composite support in tunnel design. The crown settlement, axial forces, bending moments, and load distribution in the composite support were analyzed in the light of different structural patterns. LARGE-SCALE EXPERIMENTS USING COMPOSITE SUPPORT Preparation and Procedure of the Experiments The preparation setup as well as the organized procedure of the large-scale experiments using composite support is shown in Figure 1. An appropriate geometry of the specimens was selected by considering the standard cross-section of a two-lane highway tunnel in South Korea. Under the loading conditions meant to develop the axial forces and bending moments simultaneously, arch-shaped specimens were assembled with the ends of the specimens subtending a 60° arc angle at the center of the arc circle as shown in Figure 2. The fabrication of six specimens was completed in two groups based on the dimensions of steel sets, with the first group of three specimens being reinforced by H100 (No.1, No.2, No.3) and the other three by H125 (No.4, No.5, No.6). In order to reduce the voids on the boundary of the shotcrete and steel sets, concrete was casted over the steel sets instead of using shotcrete. The specimens were designed to incorporate the uniaxial compressive strength of 21 MPa. Shear keys and steel plates were installed at the ends of the specimens, so that shear failure could be avoided at the ends and the specimens could also be protected from detachment at the fixation. Translational and rotational movements at the ends of specimens were fixed."

Jan 1, 2016