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By J. W. Cooksley

Pyrometasomatic zones are a type of replacement deposit, normally in a carbonate rock unit, which consists of a zoned, coarse-grained, generally iron-rich mixture of calcium and magnesium silicates. These zones or rock masses are also called ?skarn,? and ?tactite?. They are formed as a result of the interaction of a shallow intrusion of magma with a carbonate or calcareous host rock and are considered to be of hydrothermal origin. Three environments of pyrometasomatic deposits are depicted in Figure 1. Of course, the interaction takes place at high temperatures. Pyrometasomatic zones are categorized as calcic or magnesian, depending on whether the intrusive interacts with a limestone or a dolomite. Common pyrometasomatic zone minerals are garnet, epidote, quartz, calcite, wollastonite, actinolite, hedenbergite and diopside. Pyrometasomatic zones are of considerable economic importance because they contain ore deposits of tungsten, molybdenum, copper, lead, zinc and iron. According to Rose and Burt (1979), the chronological sequence in the formation of a ?typical? pyrometasomatic deposit is as follows: 1. Shallow intrusion of magma at 900-700°C into carbonate sediments.

Jan 1, 1981

By J. P. Rider, T. W. Beck, J. A. Organiscak

"The National Institute for Occupational Safety and Health (NIOSH), Pittsburgh Mining Research Division (PMRD) has recently developed a series of models utilizing computational fluid dynamics (CFD) to study gas distribution around a continuous mining machine (CM) with various fan-powered flooded bed scrubber discharge configurations in an exhaust curtain working face. CFD models utilizing species transport model without reactions in FLUENT were constructed to evaluate the redirection of scrubber discharge toward the mining face rather than behind the return curtain. The study illustrates the gas distribution in the slab (second) cut. The following scenarios are considered in this study: 100% of the discharge redirected back towards the face on the off-curtain side of the continuous miner; 100% of the discharge redirected back towards the face, but divided equally to both sides of the machine; and 15% of the discharge redirected toward the face on the off-curtain side of the machine, with 85% directed into the return. These models were compared to a model with a conventional scrubber discharge where air is directed away from the face into the return. The models were validated based on experimental data and accurately predicted sulfur hexafluoride (SF6) gas levels at four gas monitoring locations. One additional prediction model was simulated to consider a different scrubber discharge angle for the 100% redirected, equally divided case. This paper describes the validation of the models based on experimental data and the gas distribution results of the CFD models. INTRODUCTION To control methane gas and dust concentrations on continuous mining operations, it is important to provide sufficient quantity of fresh air from the end of tubing or curtain to the active face. In this region, operating machine-mounted water sprays and fan-powered, flooded bed scrubbers can significantly increase the amount of airflow reaching the face [1-3]. However, when an entry is large, especially in higher coal seams, the water spray configuration and the scrubber capacity may not be adequate to maintain sufficient forward airflow to confine the dust cloud to the face. Dust can roll back toward the machine operator as a result [4]. Currently, several coal mines having negligible gas emissions in higher coal seams (2.4 to 3.0 m [8 to 10ft.] thick) with exhaust tubing systems redirect the scrubber discharge back towards the face in an effort to improve dust collection. NIOSH studied the redirected scrubber exhaust techniques for dust and gas control in a full scale CM gallery to assess its potential for industry-wide application [5]. For a CM face, previous studies have concluded that the behavior of gas and respirable dust is a complex process. The distribution/dispersion and transport of gas and respirable dust after they are liberated at the face are governed mainly by their mass properties, the movement pattern of the ventilation air, and interactions with the mining machine and water droplets created by the external water spray systems used for dust control [6-10]. To understand these behaviors in a complex CM environment and to evaluate the effectiveness of various control techniques, numerical modeling has become a necessary supplement to laboratory experiments and field studies."

Jan 1, 2017

By George H. Davis

The Caribou sulfide deposit near Bathurst, New Brunswick (Figure 1) is illustrative of one variety of strata-bound sulfide deposits. It consists of numerous near-vertical sulfide lenses which are concordant to the foliation and lithologic layering of low-grade metamorphic host rocks. Pyrite is the chief mineral in these lenses, but appreciable quantities of sphalerite, chalcopyrite, and galena are also present. Rocks in the Caribou mine area belong to the Tetagouche Group of Ordovician age. They consist chiefly of (1) quartz-sericite and quartz- sericite- feldspar schists, (2) greenschists, and (3) slate and phyllite. The trends of these steeply dipping rocks define the trace of a tight, steeply plunging fold structure, the Caribou fold (Figure 2). This fold plunges approximately 750 to the north-northwest; its axial plane strikes N.20°E. and dips steeply westward. Sulfide lenses of the Caribou deposit are associated spatially with the Caribou fold. The deposit is located in the fold along the contact between quartz-sericite and quartz-sericite-feldspar schists on the hanging wall and quartz-chlorite-sericite phyllites and graphitic schist on the footwall (Figure 3). Genesis of the Caribou deposit is ambiguous because its strata-bound form suggests syngenetic sulfide deposition, whereas its location within a fold suggests structurally controlled epigenetic mineralization. Acceptability of a particular genetic model rests on establishing the time of mineralization relative to deposition, deformation, and metamorphism of the associated rocks. To establish the timing for Caribou mineralization, the deformational histories of rock and sulfide, respectively, were compared. Epigenetic and syngenetic models can be tested against this interpreted structural history of the Caribou deposit.

Jan 1, 1971

By A. L. de Vegt

Hydrogen sulfide is an expensive chemical used in nickel, zinc and copper mining and metallurgical operations for selective recovery and concentration of metals from leach water streams, acid plant blow down streams, refinery electrolyte bleeds and precious metal plant bleeds. Hydrogen sulfide is either produced on site by catalytic reduction of elemental sulfur or transported to the site as liquefied hydrogen sulfide (H2S) or as a sodium sulfide solution (NaHS). Biologically produced hydrogen sulfide has economically very interesting application possibilities in the mining and metallurgical industry. Converting sulfates from waste streams into usable hydrogen sulfide by biological reduction results in operational cost savings in existing lime treatment systems. H2S can be produced biologically for less than $500/ton S. For the past ten years Paques has been engaged in the development and installation of treatment systems based on biotechnological processes to remove sulfur compounds from water, air and gaseous streams. Paques has designed and installed a groundwater treatment system for the Budelco zinc refinery in the Netherlands to remove sulfate and heavy metals. The hydrogen sulfide produced is used for recovery of metals, mainly zinc, from the ground water stream. The system has been operating since May 1992 treating a flow of 5000 m3/d. At Kennecott's Bingham Canyon Utah copper mine a pilot plant started operation in November 1995 to develop the process for selective recovery of copper from leach water using biologically produced hydrogen sulfide from sulfate containing groundwater. Other pilot plants are operated at DOE's Pittsburgh Research Center and at Cominco Research focusing on selective recovery of metals.

Jan 1, 1998

By W. J. Atkinson

Since the inception of the Ashton (formerly Kalumburu) Joint Venture in 1972 the parties have expended 524 million in exploration for diamonds in the Kimberley region. This has resulted in the discovery of the currently subeconomic Ellendale deposits in 1976/77 and the economic Argyle - Smoke Creek Deposits in 1979/80. In addition to Argyle and Ellendale some 90 kimberlitic and lamproitic bodies have been discovered grouped broadly into three provinces, on the west, east and north margins of the Kimberley block. These bodies range in size from dyke-like features less than one metre in width to pipes with a surface area of 128ha. The bodies with larger surface area are volcanic crater deposits, infilled with air-fall and water deposited tuffs and epiclastic sediments.

Jan 1, 1984

By W. J. Wuest

The U.S. Bureau of Mines (USBM) has recently developed a rock mass classification system for evaluating the structural competency of bedded roof strata; the Coal Mine Roof Rating, or CMRR. When compiled with the companion Lotus 1-2-3 spreadsheet, which is simple to learn and use, CMRR data are a useful tool with applications to longwall gate road pillar design, safety hazard mapping, and artificial roof support analysis. This paper demonstrates these applications under actual conditions found in current U.S. mining operations.

Jan 1, 1995

By J. D. Crone

Crone Geophysics Limited in co-operation with Newmont Exploration Limited has developed a ground Pulse electromagnetic method. This is the first unit in a planned integrated system of surface and borehole Pulse EM equipment. Newmont had previously developed an operational Pulse EM unit for use in areas of very high surface conductivity. The Newmont equipment was large, heavy apparatus that required motorized transport. It operated in the equivalent frequency spectrum of 10Hz to 2.5Hz. The basic aim of Crone Geophysics was to design a Pulse EM system more portable than Newmont's. We wanted to operate in all types of field conditions including heavily wooded and mountainous terrain areas. We also wanted to record the higher frequency information that is contained in the Pulse EM waveform. There are three reasons why we thought this high frequency information was important in survey applications: (1) Field tests conducted over massive sulphide bodies in the Arizona desert showed that the desert weathering process tended to break down the electrical contact between sulphide crystals. The net effect is to reduce the conductivity of a massive sulphide body, particularly narrow bodies or highly fractured sulphide zones. In order to detect such occurances the higher frequency information is essential. (2) We wanted to be able to detect occurances with sulphide content as low as 5% sulphides that are usually poor to moderate conductors. (3) We also wanted to be able to determine the presence and extent of surficial conductive formations and clay deposits since many airborne EM anomalies are caused by such bodies. If we have the capability of detecting and recognizing these formations we would be able to explain the airborne anomaly.

Jan 1, 1976

By D. R. Bomberger

An automatic microscope has been developed to .measure the size and populations of macerals and minerals in fine coal particles. Differentiations are made on the basis of reflectance. This study is concerned with the size distribution of pyrite inclusions. Most fine coal cleaning processes do not remove pyrite as completely as a straight density separation. Consideration of the pyrite size distribution is suggested as a more accurate method of predicting sulfur reduction by a cleaning process. Analyses of float-sink results and Deister Table operation in terms of pyrite particle sizes are made. Other potential applications of automatic microscopy are also discussed.

Jan 1, 1963

By Keros Cartwright

Sanitary landfilling has become one of the most widely used methods of disposing of solid refuse. A principal concern of regulatory agencies and the public itself is that landfill operations do not degrade the physical environment, including water resources, and the ground-water reservoir in particular. Ground-water and engineering geology can guide landfill operations into suitable terranes or develop measures to compensate for any natural limitations at a particular site Experience and research in Illinois suggest four activities relating to landfill disposal that warrant attention by geologists and engineers: (1) Regional delineation of favorable and unfavorable hydrogeologic conditions to facilitate planning and preliminary screening of potential landfill sites. (2) Site evaluations, with considerations of geologic materials, topography, water levels, flow systems, and local occurrence and use of water resources. (3) Re- search on aspects of the hydrogeologic environment that control effects of, or are modified by, landfills. (4) Formulation of practices in the siting, construction, and operation of landfills that prevent, mitigate, or isolate deleterious effects. The first two activities are basically in the domain of earth science, requiring the application of fundamental concepts of geology and hydrology and conventional site-exploration methods. The third activity, research, requires contributions from geology as well as other disciplines, including soil physics, sanitary engineering, and chemistry. The fourth calls for policy decisions by regulatory agencies and elected officials, using the contributions of scientists and engineers.

Jan 1, 1970

By John W. Brauns

18.1-RAILROAD JOHN W. BRAUNS Conventional railroad haulage can be employed at both open-pit or strip and underground mines-in the latter case, largely for transfer of ore from distant openings to processing plants, or processed material to loading points or docks, using standard hopper cars for bottom unloading or gondolas for rotary dumping. The major application, however, is in surface mining for moving ore and/or waste out of the pit to a crushing plant or dump. Consequently, the following will deal largely with this phase of railroad operation, though the conclusions apply equally, for the most part, to other rail-type surface haulage. In surface mining, trains consisting of a locomotive and gondola or side-dump cars suitable for loading by power shovels are used. Gondolas are restricted to hauling ore as a rotary dumper is required. Side-dump cars are more versatile, carrying both ore and waste, but because of their additional dumping mechanism they are likely to be more expensive to maintain.' Also they weigh up to twice a flat-bottom car of the same capacity and. therefore, fewer" cars can be hauled per train. Standard-gage track is most commonly used. Track systems incorporate low-quality temporary track where moves are frequent and permanent high-quality track on main lines. Rail haulage can be used alone, or in combination with other surface haulage methods, thus permitting a selection best adapted to the peculiar requirements of each mining project. 18.1.1---GENERAL APPLICABILITY, CONTROLLING PHYSICAL CONDITIONS For handling rough rock, the shovel-train system is unexcelled.' The ideal applica¬tion is in a large, but not excessively deep, open pit mine from which the coarsely blasted ore and waste must be transported over 3 mi. If. in addition, a high production rate is to he maintained, railroad haulage probably will afford a lower cost per ton transported. Grade must he relatively gentle-usually 3% uphill and 4% downhill. The greater the differences in elevation involved, the greater are the track grade space requirements; for example, a 3 c ramp out of a pit only 300 ft deep is almost 2 mi long. Main-line track locations should he selected carefully so that the number of moves during the life of the mining operation can he kept to a minimum. This applies both to the ore haulageway and that for waste. Such moves are not only expensive, but are difficult to execute without adversely affecting production rates. The large mine affords greater opportunities for judicious location of semipermanent trackage. Figs. 18-1 and 18-2 illustrate typical track layouts. The effect of terrain in considering railroad haulage is confined chiefly to the initial cost of the installation. Grade construction in mountainous territory is ap¬preciably more expensive. However, if that expense can be borne, the subsequent maintenance cost of trackage will not he much higher than in areas of low relief.

Jan 1, 1973

By Leonardo Rosas Sánchez, Darío Ángel Bulla

"The two track road sector between Cisneros-Loboguerrero (having a length of 14 km and 11 short unidirectional tunnels) is a new highway still on construction located along the existing Highway Buga – Buenaventura (Colombia). Due to the steep topography, difficult geological/geotechnical conditions, the traditional portal construction approach was impossible to be implemented in eleven (11) of the twenty two (22) portals. In this specific project, the skewed portal approach was developed as the optimal and more effective solution. The construction time and costs of portals were reduced in 21 months and 75%, respectively. At the same time, the natural equilibrium of the slopes was maintained, thus, facilitating adequate safety factors along the useful life of the project. This document pretends to show a detailed design experience (and the construction of the entry portal of tunnel 11 (left)). INTRODUCTION The Cisneros-Loboguerrero project is a 14 km length dual lane highway, connecting productive zones with the Pacific Ocean along the current Bogota-Buenaventura highway as shown in Figure 1. The project is located at the northern side of the Dagua River Valley. The preliminary design suggested constructing portals under challenging topographical conditions, i.e., slope cuts having heights between 50 to 100 m (some having slopes > 100%) requiring complex developments and having very high risks.The entry portal of tunnel 11 (left) was the first portal successfully built by implementing the skewed portal approach. Later, this approach was used as a model for the construction of the other ten (10) portal having similar topographic and geotechnical conditions. The development of this new alternative provided a considerable reduction on the construction time of portals, thus relieving a critical path in this project."

Jan 1, 2016

By G. T. Austin

Every year the United States consumes millions of dollars worth of abrasive materials as blasting media. Entrained in either a gas or liquid stream or propelled by paddles or wheels, they are directed onto the surface of another material to modify that surface. The modifications to impacted surfaces include cleaning, cutting, deburring, etching, finishing, and peening. Blasting media can be either organic or mineral abrasive materials. Information and data presented are for only a portion of the mineral abrasives, they are; fused aluminum oxide, coal slag, copper slag, garnet, metallic shot and grit, nickel slag, olivine, silica sand, silicon carbide, and staurolite.

Jan 1, 1994

By Richard Crowell, James Gillaspie

A concentrate biooxidation process was successfully demon­strated in the field in a remote part of northwestern Mexico. A 275 tonne (300 st) biooxidation heap was constructed using GeoBiotics' proprietary GEOCOAT™ coated concentrate process. The pyrite/chalcopyrite/sphalerite concentrate was bioox­idized in the heap for 60 days. Cyanide leach recovery of the con­centrate increased from 68% gold recovery at a cyanide consump­tion of 1.6 kg NaCN/g Au (llO lbs/oz) in the as-received concen­trate, to 94% gold recovery at a cyanide consumption of 0.37 kg NaCN/g Au (27 lbs/oz) in the biooxidized concentrate. The heap was constructed at a rate of7 tonnes (7.5 st) concentrate per hour, using typical heap leach equipment and easily scalable methods. Heap operations demonstrated that energy dissipation in the humid summer environment was easily controlled by low pressure aeration and management of solution chemistry and application. Observations of the demonstration heap appear to support the presence of reflux of moisture within the biooxidation heap.

Jan 1, 1998

By Michael Werner

A three-way research program, facilitated by the U.S. Bureau of Mines Generic Institute funding, conducted by Hecla Mining Co., Spokane Research Center of the Bureau and the University of Idaho, shows that a cooperative effort to solve difficult mining problems should be considered. A five-year plan to change an overhead cut-and-fill mining system to a longwall undercut-and-fill involves more than twenty people from three organizations. The investigations will eventually include, ground stress, stress analysis, fill selection placement and compaction, ground and fill support, underhand mining and materials handling, access, ventilation, equipment selection and synthesis and operations and cost simulation.

Jan 1, 1985

By Robert M. Cox

A thorough geological engineering investigation is required before surface lands overlying abandoned underground mines can be safely recommended as building sites. The major problems confronting the geological engineer are assembling accurate geologic and mining information and developing an accurate rock mechanics model of the situation. A successful investigation requires a combination of technical expertise in rock mechanics and engineering geology tempered with practical engineering judgment. The results of a good study are not always favorable to the prospective builder.

Jan 1, 1975

By Zoheir Khademian, Morgan Sears

According to the 2010–2019 Mine Safety and Health Administration (MSHA) accident report database, 91% of reported ground control accidents in US longwall mines were caused by roof instability. Gateroads are subjected to significant changes in loading conditions from the development to the longwall abutment loading phases. When combined with thinly bedded shale roof, found in many US longwall coal mines, the design of efficient roof support becomes challenging. In previous work, the bonded block modeling (BBM) of roof by UDEC was validated against field extensometer measurements in a longwall entry roof at a 180-m depth of cover. The BBM was shown capable of capturing delamination and buckling of shale roof, one of the main roof instability mechanisms in longwall mines. This paper presents the recent findings on the roof-support interaction using BBM models of the same longwall entry. The effects of cable bolts, roof bolt density, and strap support on potential roof instability are studied. Results demonstrate the potential for BBM numerical models to help understand the complex roof and support system interactions and to assist with optimizing gateroad support systems.

Feb 13, 2024

By Antonio Nieto, Jesus Castillo

Research and Development (R&D) departments in the mining sector are essential for creating new solutions on productivity, safety, and sustainability. Nevertheless, the selection of R&D projects is complex, often influenced by subjective judgments and uncertainties. This paper explores the application of the Multicriteria Decision Analysis (MCDA) as a structured approach to evaluate and prioritize innovation projects based on various criteria such as safety, cost, environmental impact, and social acceptability. By assigning weights and quantifying criteria, MCDA enhances decision-making transparency and objectivity. This study aims to show a method that facilitates strategic thinking, resource optimization, and stakeholder engagement, ensuring that selected innovations align with the company’s long-term objectives and commitment to responsible mining practices.

Feb 1, 2025

By Javad Sattarvand, Amin Moniri-Morad

Predicting equipment failure behavior plays a critical role in providing a safe operation. Although various reliability evaluation methods are available for estimating failure behavior profiles, these approaches are based on mathematical formulation, leading to actual operation simplification and improper estimation of failure trends. This study proposes a discrete-event simulation (DES) approach to model fleet failure behavior. This approach can model the maintenance strategies in multi-component systems with minimum simplifications. In this regard, the first step was to collect a historical failure time dataset (e.g., the time between failures). Then, the DES model is established to predict the severity of failure events and design maintenance strategy considering actual operation circumstances. Afterward, the maintainability analysis was performed to estimate equipment downtime and availability. The achieved results showed that the system availability was about 85%. Also, the findings demonstrated that the DES could efficiently predict the equipment failure behavior using various stochastic events.

Jun 25, 2023

By Chuang Sun, Feng Luo, Guo‑dong Li, Xue‑qing Li, Tuan He

The mining-induced failure of the coal seam floor is essential for water inrush. The mining disturbance to the floor, especially in the thick coal seam, is severe, and the water inrush risk is also higher than that in regular thick coal seam excavation. The superposition of many stresses, including in situ stress, mining-induced stress, and confined water pressure, must be considered in the prediction of the floor failure depth. This study adopted the elasticity analysis, FLAC3D numerical simulation, and on-site acoustic wave test comprehensively. The thick coal seam working face of the Zhong-Yu coal mine affected by confined water was selected as the engineering background to study the characteristics of the floor failure. Based on elastic foundation theory and the superposition principle, the mechanical model and the failure depth criterion of the floor were established, respectively. The distribution and evolution of mining-induced stress and the plastic zone in surrounding rock during the mining process are obtained by FLAC3D. In addition, the changes in the P-wave wave velocity in the floor before and after mining were compared and studied by the acoustic wave test method. The range of floor damage depth is determined on the basis of the above research.

Jun 8, 2022

By Michael J. Friedel

The permeability and flow capacity in unsaturated media is investigated by the Bureau of Mines for application to in situ copper leach mining at the Cyprus Casa Grande mine site. Moisture retention properties are derived and combined with scanning electron microprobe data to characterize the mineralogy, texture, pore size, distribution, and permeability of the host rock. Finite element modeling is used to derive a saturated permeability, ambient degree of saturation, and assess various injection-recovery schemes. Recommended design modifications for optimization of solution distribution and maximum recovery from the rock matrix requires either (1) the injection pressures on the order of 1500 psi and recovery wells operating in a suction mode, or (2) performing permeability enhancement, through rubblization. By producing a maximum block diameter of 4 m, injection pressures can be reduced to 500 psi with improved recovery and containment of solutions.

Jan 1, 1991