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By W. Holding

Since the 1975 International Mine Ventilation Congress in Johannesburg there has been a trend in South Africa towards making the mine ventilation departments responsible for monitoring the total environment. This includes the taking of noise and illumination measurements and there is in fact a debate taking place as to whether the departmental title should be changed to 'Environmental Control Department'. The organisers of the 2nd international Mine Ventilation Congress have decided that noise and illumination will not be included as Congress subjects and 'Total Environment' includes only those facets which are open to debate at the Congress. The choice of mine is significant in that while most Congress papers from South Africa will be devoted either to coal mining or to the somewhat unique deep level gold mines, Prieska Copper Mine is a mine which can easily be identified with similar mines in many other parts of the world. The mine is situated some 750 km south west of Johannesburg and about 600 km north east of Cape Town. Current production (ore and waste) is about 340 000 tons per month and the total underground labour force is just over 2 000. The ore body is a massive sulphide, the main minerals being copper and zinc and the method of mining is sub-level open stoping. Daily average surface temperature conditions range from 85°F (29.5°C) dry bulb and 69.8°F (21°C) wet bulb in mid-summer to 42°F (5.5°C) dry bulb and 36.5°F (2.5°C) wet bulb in mid winter. The information presented in-this paper is limited to what can be gathered by mine ventilation staff as part of an on-going exercise and is obviously not as comprehensive as would be the case if a fully equipped research establishment were to become involved. The paper will be divided into three sections 1) Gases 2) Dust 3) Heat In each section statutory and/or other standards will be set down followed by a discussion of assessment and in some cases control methods.

Jan 1, 1980

By Ernest A. Draeger, James W. Collins

Water only cyclones, sometimes referred to as hydrocyclones, are one of the newest types of coal processing equipment. These devices have achieved wide acceptance as fine coal cleaners in the past decade. Many metallurgical coal plants employ water only cyclones to process 0.5 mm x 0 size coal. Some of these plants have as many as 40 to 50 305-mm-diam units with each unit receiving as much as 9 t/h of raw feed. The growth in the utilization of hydrocyclones is due partly to the energy shortage, partly to the general increase in over-all coal preparation, and also because of a need for a simplified fine coal (0.5 mm x 0 size) gravimetric separator. Large diameter water only cyclones are also available and in use to process feed sizes up to 32 mm in size. However, the size normally employed for cleaning 0.5 mm x 0 coal are 356 mm or 305-mm-diam for single-stage circuits. In two-stage circuits, the secondary units are normally the same diameter as the primary units or smaller, such as 203-mm-diam. By using the small diameter cyclones and treating a closely sized feed, 0.5 mm x 0 only, it has been found that the probable error or imperfection of the water only cyclones is comparable to that obtained on the same size fraction treated in a large 610-mm-diam heavy media cyclone washing 38 mm x 0. The water only cyclone can approach the efficiency of a heavy media cyclone when cleaning fine solids because it creates its own dense media by accumulating high specific gravity particles in the wide angle conical section of the cyclone. A cut-away cross sectional view of a water only cyclone is shown in Fig. 1. It is also true that when treating a wide range of sizes (38 mm x 0) in heavy media cyclones, the smaller size particles (0.5 mm x 0) separate in proportion to the split of the media through the cyclone rather than by particle density.

Jan 8, 1980

By Diler Katircioglu-Bayel

This study aims to investigate the effect of combined mechanical and ultrasonic milling on the size reduction of talc. First, the talc sample was wet-ground in a stirred media mill for five different lengths of time (30, 60, 90, 120 and 150 min), and the optimum result was subsequently achieved with treatment by ultrasonication. The effects of amplitude (20, 35 and 50 µm), solid ratio (2.5, 5, 7.5 and 10 percent), and sonication time (60, 120 and 240 min) on the sizes of the final product were investigated. The pre-milling by wet grinding caused a decrease in the grinding resistance of talc. Sequential ultrasonic treatment, which was applied to the talc sample, generated smaller particles in comparison to those acquired by stirred media milling alone. Experimental results were assessed based on the product particle size (d10, d50 ), reduction ratio and specific energy consumption. Submicron particles prepared by ultrasonic treatment were highly stable compared to stirred media milling alone as investigated in terms of particle size. In addition, the effects of mechanical and ultrasonic milling on the structural properties of talc particles were characterized by X-ray diffraction (XRD) analysis.

By Steve Skelhorn, Dan Ifrim

"A tunnel project poses many challenges; the operation of the Tunnel Boring Machine (TBM) being one of them. Mechanized tunneling is known as a safe and effective alternative to other methods in terms of schedule and cost; however, efficiency can be severely affected by a bad TBM selection and qualification and employment of inexperienced operators. The success of a mechanized tunneling project involves a comprehensive and interdisciplinary consideration of all contributing factors such as TBM technical specification and selection, TBM design and procurement including ancillary equipment and tunnel linings. The tunnel equipment selection along with the operation can make or break the project. The objective of this paper is to address the importance of the skills and qualifications of the TBM crew with particularity to the TBM Operator. The study includes the Owner and Consultant involvement in the selection and pre-qualification of the TBM crew and specifically the TBM operator as well as the role of Contractor and TBM manufacturer in TBM operator training. This paper also analyzes the possibility of issuing a TBM operator certification, and discusses the benefits and significance of periodic training and certification programs. INTRODUCTION Training in the tunneling industry is not a new topic. The industry continues to evolve and become more complex with technology advances and expansion of mechanical tunnelling to mechanized shaft construction, large diameter drilling and mining industry applications. The need for professionals trained to operate mechanized tunnelling equipment is ever increasing, while there is a significant number of veterans who will be ageing out in the next 5 years. Consequently attracting young professional is a very important aspect of sustaining a qualified pool of professionals. For any given tunnel project, the owner and the engineer spend up to several years, studying the ground conditions during preliminary and final design. Post contract award the contractor spend additional months studying the ground again to develop the optimum means and methods for construction. All this time and money spent at the beginning of the project has the purpose of developing the optimum tunnel design, assessing the risk associated and implementing mitigation measures to reduce risks to acceptable levels. Following the tunnel design process, sophisticated TBMs are being specified and sourced to ensure the best tool for the job. The question raises here: Are there available experienced/trained professionals capable of operating these sophisticated machines?"

Jan 1, 2016

Underground instrumentation and observations at longwall panels have demonstrated that the growth of main roof causes an extremely high roof weighting on the shields. It can sometimes result in catastrophic effects on the support when the roof weighting intensity far exceeds the support capacity. In this paper, a comprehensive study was conducted on characteristics of main roof breakage and its effects on shields at different locations, based on the monitored shield data, theoretical analysis, and finite element analysis. With the help of theoretical analysis and numerical modeling, stress distribution and redistribution in the main roof were analyzed in detail to define main roof failure modes and understand the maximum roof weighting intensity imposed on the shields. From this study, it was found that the effects of main roof breakage on shields are chiefly related to the shield initial setting condition and the final failure mode of the main roof.

Jan 1, 1994

By Edgar O. McAlister

Associated with cordilleran intrusives of intemediate to acidic composition, gold/silver ores are generally found in the intruded host rocks which are adjacent to these intrusives. Generally precious metal deposits lie further from the intrusives than allied base metal deposits. For vented intrusives, the associated volcanics may constitute the intruded rock and form the host for precious metal accumulation. Potential field methods, particularly magnetics, can help to define unseen boundaries of intrusive systems and thus can point to generalized prospecting targets. Other clues arise from the intrusive system type, its emplacement fracturing, the host rock type and local magnetic changes caused by mineralization processes.

Jan 1, 1984

By L. Alan Weakly

The U.S. Department of Energy (DOE) has entered into a $l.5 million Cooperative Agreement with Alpine Equipment Corporation/Astro International Corporation ("Alpine") of State College, Pennsylvania, for the evaluation of water-jet-assisted (WJA) mechanical cutting of oil shale under actual mining conditions. A commercial-sized, heavy WJA mechanical miner is being assembled based upon the successful "factory testing" of a smaller prototype miner utilizing standard tungsten-carbide and Polycrystalline Diamond Composite (POC) bits in large oil shale boulders. Actual field testing of the machine will be conducted in an oil shale mine located in the Piceance Basin of Western Colorado. In-mine logistical support is being provided by several oil shale companies through the Colorado Mining Association (CMA) and the U.S. Bureau of Mines (USBM).

Jan 1, 1990

By A. Nieto

Rare earth elements (REEs) are crucial to green technology such as hybrid-electric vehicles, wind turbines and fluorescent light bulbs. As of 2011, China dominates the global production of REEs and is reducing its export quotas. To predict the supply of rare earths in the United States based on future supply scenarios, a web-based database and geographic visualization tool was built. Five case scenarios with varying levels of REE demand were created by varying several economic conditions including (1) international trade policy, (2) greenhouse gas regulations, (3) environmental mining regulations and (4) tech applicability ratio of REEs. The most likely scenario, which is based on current international demand levels, indicates the importance of expediting the development of extractive operations of current REE resources within the United States. The results of the different case scenarios are supported by using dynamic geographic maps indicating the location of rare earth ore (REO) resources.

Jan 1, 2012

By Edward C. Heistermann

The Falkirk Mining Company, a wholly owned subsidiary of The North American Coal Corporation, is located 80 kilometers (50 miles) north of Bismarck, North Dakota. Falkirk is under contract to provide 5.08 mil- lion tonnes (5.6 million short tons) annually to the Coal Creek Generating Station, an 1100 mega- watt electric plant owned by the Cooperative and United Power Associations of Minnesota. Coal Creek is located 2.4 kilometers (1 ½ miles) south of the Mine. Electricity from the plant is transmitted to rural electric customers in Minnesota via a 400-kilovolt D.C. power line.

Jan 1, 1982

"INTRODUCTION In recent years, there has been increasing focus on environmental and social impacts of the extractive industries, climate change and resource scarcity. The concept of the circular economy aims to replaces the “take-make-dispose” economic model with one that eliminates waste of all kinds and is restorative by design. Such closed-loop systems implicitly aim to reduce the quantity of primary extracted materials entering the economy, thereby affecting supply and demand dynamics, hence mining industry economics. For the metals industry, the ability to engage in, or adapt to the circular economy can be heavily affected by industry structure and geographical factors. Eco-efficiency initiatives that reduce waste and environmental impact may help the mining and metals industry align with some of the goals of the circular economy. This paper focuses on base metals, and explores case studies in copper, lead and zinc. It analyzes primary and secondary metal production, and recycling. It examines company structures and how these affect engagement with the circular economy. CIRCULAR ECONOMY PRINCIPLES Ellen MacArthur Foundation (2012) describes the circular economy as “an industrial system that is restorative or regenerative by intention and design”, which “replaces the ‘end-of-life’ concept with restoration”, and “aims for the elimination of waste through the superior design of materials, products, systems, and, within this, business models”. The concept is systems focused. For materials such as metals, a series of loops are considered, including maintenance of devices, reuse, refurbishment and recycling. Potential methodologies to achieve circular economy outcomes include disassembly and reassembly of manufactured goods, leasing rather than buying major appliances, and converting to renewable energy sources. The circular economy is partially aligned with the principles of eco-efficiency, which relate to reducing the environmental impact per unit of a material produced. PRIMARY AND SECONDARY METAL PRODUCTION Base metals (copper, lead, zinc and nickel) are essential ingredients in modern economies and are key commodities produced by the global mining industry. Metal production can be categorized as primary or secondary. Primary metal comes from the processing, smelting and refining of metal content extracted from ores, while secondary production comes from metals recovered from recycled streams (e.g. recycled lead-acid batteries, copper wire scrap, etc.). Metals are stored in natural, anthropogenic in-use and anthropogenic waste stocks. An example of the stocks, flows and processes associated with global copper extraction and use is shown in Figure 1."

Jan 1, 2018

By Andrea Biagi, Elisa Comis, Gianluca Bella, Enrico De Panicis, Guido Barbieri, Matteo Giani

The Sotra Link Project is a major infrastructure project in Norway involving the design, construction, financing and maintenance of several underground and surface structures between Sotra island and the city of Bergen, among them 23 tunnel portals, 12.5 km of tunnels and a 900 m long suspension bridge. This paper describes the benefits in applying a Building Information Modelling (BIM) approach to tunnelling, from Early Design to the Detail Design Phase. The BIM application to the Sotra Link Project resulted in several improvements, such as efficient handling of clashes and inconsistencies, deeper understanding of effective design choices (reduction of errors), more efficient communication between designers, enhanced control of project quantities and costs. The advantages of the BIM approach during the ongoing Construction Phase are also explained.

Jun 23, 2024

By Neil D. Donnell, O&apos

Ore reserve estimation at the Syncrude Canada Ltd. open-pit oil sands mine in Northern Alberta has evolved since the project's inception. Early techniques followed a conventional petroleum reservoir analysis format, with relatively widely-spaced drill holes and semiquantitative grade data. Experience has developed a more standard mining approach, including classification of geological materials by both lithology and sedimentary origin, timely and multi-purpose drill holes, precise analytical data, empirical recovery factors, a computerized geological data base, and an ore body block model. Future efforts will involve enhancement of existing techniques, use of geostatistical algorithms, quantification of confidence limits, and improved control of the ore model by geological parameters.

Jan 1, 1985

By M. A. Trevits, A. Ozment

"According to the Office of Surface Mining Reclamation and Enforcement Abandoned Mine Land Inventory System, in 2013 there were 98 underground mine fires burning in 9 states. This is considered by experts to be an underestimate for the actual number of fires nationwide. Abandoned mine fires, if left uncontrolled can burn for years and in fact, one of the most well-known mine fires in the US, the mine fire in Centralia, PA, which began in 1962 has been burning for over 55 years. In Centralia, the mine fire won the battle, despite suppression and control efforts, as most of the residents were bought out by the State of Pennsylvania and moved away. However, the world record for the longest-burning coal fire, which may have been started around 6,000 years ago in New South Wales, Australia is still smoldering. Suppressing a coal mine fire requires cooling the hot zones and removing any source of oxygen. If the workings are shallow, the fire zones can be unearthed and the burning rock mass can be quenched on the surface. If the workings are too deep to excavate, then the fire must be fought remotely through boreholes using a variety of agents including water, gas-enhanced foam and grout. Access to surface areas for drilling can be problematic due to topographic and property constraints. When this occurs, large areas of burning may go unaddressed or simply left to burn. Fire Solutions, Inc. has been investigating the use of gas-enhanced foam in concert with directional drilling technology. Gas-enhanced foam has the advantage of using less water and adds inert nitrogen gas to displace oxygen to infiltrate and suppress a fire. Directional drilling has the capability to steer a borehole to a specific place underground. Directional drilling has many advantages over conventional drilling technology as it can provide the least disruption to the ground surface, minimize surface preparation and reclamation costs, multiple sites can be accessed underground from a single site and thus treated simultaneously and it offers increased efficiency because it is not constrained by difficult terrain. This paper discusses the combined use of these two technologies and it is hoped that with the use of these two technologies the efficiency and capability to address mine fires will be significantly improved. INTRODUCTION According to the Office of Surface Mining Reclamation and Enforcement, Abandoned Mine Land Inventory System, in 2013 there were 98 underground mine fires in 9 states. This is considered to be an underestimate for the actual number of fires nationwide. Many mine fires are started by people burning trash where the coal seam or an abandoned coal mine is close to the surface. Other fire ignition sources include lightning and forest fires. Once ignited, a coal mine fire can easily spread into the remaining coal pillars and mine entries. Once established, the fire creates its own ventilation system supporting further combustion by drawing air down into the workings through unsealed mine shafts, fractures and surface subsidence depressions. As the coal left in the workings from the past mining operations burns, the mine void can collapse, causing subsidence and creating dangerous voids, damaging damage overlying surface structures and roadways. The products of combustion include smoke and noxious fumes such as carbon monoxide gas. These products are released to the atmosphere through fractures that develop within the ground surface, killing vegetation and creating serious health hazards [1]."

Jan 1, 2018

By Richard B. Jacob

The High Gradient Magnetic Separator (HGMS), also known as the High Gradient Magnetic Filter (HGMF), is an effective device utilized in magnetic separation. This method of separation is gaining popularity in the separation of sub-micron material containing feebly magnetics. The most common use of this type of separator is in the removal of iron stained particles to improve the brightness of kaolin clay. Potential areas for use of this magnet include: (1) desulfurization of coal (2) the clean-up of mill effluent (3) removal of fine particulate matter from municipal and industrial waste (4) desulfurization of oil

Jan 1, 1983

By T. E. Wilson

An exploration bore core sample of coal ought to be reduced from its original cylindrical form to a particle size distribution and particle composition that reflects, insofar as possible, a process stream of? raw? coal it represents. Often, coal cores are reduced with a laboratory crushing machine, the product of which may not match the raw coal size distribution or size fraction composition. This study employs drop-shatter impact breakage followed by dry batch tumbling in a steel cylinder rotated about its transverse axis in order to characterize the core material in terms of first-order and zeroth-order breakage rate constants. These are indices of the propensity of the coal to degrade during excavation and handling. Initial drop-shatter and dry tumbling tests were done with synthetic cores, to reduce material variables and . conserve difficult-to-obtain coal cores.? Cores of three different coal beds --Illinois No.6, Upper Freeport, and Pocahontas No. 5 -were subjected to drop-shatter and dry batch tumbling tests to determine breakage response. Comparison of coal preparation plant feed with a crushed bore core and a bore core prepared by drop-shatter and tumbling (all from the same Illinois No.6 coal mining property) indicated that the size distribution and size fraction composition of the drop-shattered/tumbled core more closely resembled the plant feed than the crushed core.

Jan 1, 1998

By J. Espí

The mineral price assigned in mining project design is critical to determining the economic feasibility of a project. Nevertheless, although it is not difficult to find literature about market metal prices, it is much more complicated to achieve a specific methodology for calculating the value or which justifications are appropriate to include. This study presents an analysis of various methods for selecting metal prices and investigates the mechanisms and motives underlying price selections. The results describe various attitudes adopted by the designers of mining investment projects, and how the price can be determined not just by means of forecasting but also by consideration of other relevant parameters.

Aug 1, 2013

By Jacques B. Wertz

It is well known that the major fractures and lineaments presently recorded in Western North America are preferentially oriented along a general northwest direction (Figure 1). There are other features, however, more subtle, more elusive as a rule and which can only be inferred, occurring at right angle to this broad NW direction. It is intended a) to examine some of these NE or transverse trends, b) to compare these regional NE breaks to similar ones that transversally cut through the eastern part of the European Tethys, more specifically in Iran and Turkey, and c) to study their potential relationship to mineralization in both areas.

Jan 1, 1973

By Błażej Doroszuk, Robert Król

Mill drums are essential equipment in various industries for the comminution of materials. To optimize their design and operation for efficient and cost-effective processing, it is necessary to understand the behavior of the mill drum under various operating conditions. This study investigates the behavior of a mill drum using a combination of experimental and numerical methods. The factors that can influence the behavior of the mill drum, such as the size and shape of the mill, grinding media, rotational speed, filling level, and material properties, are discussed. Experimental methods can be limited in obtaining measurements of internal processes, so numerical methods such as the Discrete Element Method (DEM) are also used to simulate the behavior of the mill drum. In this study, the experimental measurements of the motion of the grinding media are obtained using computer vision methods, and the numerical simulations are calibrated using the experimental results. A designed experiment approach is used to evaluate the performance of the mill drum under various operating conditions. The results of this study can be useful for the design and optimization of mill drums to achieve better performance and energy efficiency.

Jun 25, 2023

By C. A. Oestreicher

For sulfide minerals, the presence of dissolved oxygen in the water phase is an influencing factor for separation by flotation. Klassen and Mokrousov(I:217l distinguish three stages of oxygen adsorption; namely, reversible adsorption, activated adsorption and, finally, surface oxidation. While contraversial, limited adsorption of oxygen is believed to improve the interfacial reactivity between collector and mineral. Intensive surface oxidation of sulfide minerals usually results in unsatisfactory flotation with collectors of the xanthate type. The influence of dissolved oxygen in the water phase has received consideration for sphalerite, galena, chalcopyrite, arsenopyrite, chalcocite, and covellite(2,3,4,5,6). However, the nature of surface oxidation products of sulfide minerals has received very limited investigation(6,7). Lightly oxidized galena promotes the adsorptive reaction of surfactant (xanthate or dixanthogen). Tolun and Kitchener(8) state that limited interaction occurs between galena and xanthate under relatively reducing conditions. And, that exposure to oxygen raises the electrochemical potential of the galena to that required for reaction with xanthate or dixanthogen. In the latter condition, the galena has an "effective flotation surface". On the other hand, intensive oxidation of galena reduces the chemical reaction with xanthate collectors (9) . Complete flotation with xanthate-type surfactants with increasing oxygen content in the water phase has been determined to have the following sulfide mineral sequence(3): galena, pyrite, sphalerite, chalcopyrite, pyrrhotite and arseno-pyrite. The work of Cusack(4) suggests that some threshold amount of oxygen is necessary for flotation to occur, but heavy oxidation hinders flotation with xanthates. According to Tolun and Kitchener(8) catalytic oxidation of xanthate to dixanthogen occurs. From infrared studies, Poling and Leja(IO,II) found that in the absence of oxygen in solution, xanthate ions do not adsorb either on

Jan 1, 1972

By L. Eros, R. H. King

The US Bureau of Mines has funded several research and development projects in computerized mine monitoring and control. Hardware and software components have been sufficiently developed so that mine operators have been provided with an efficient means to comply with federal regulations and increase mine safety. Several cost benefits have been realized as well, particularly with increased conveyor belt haulage availability. Western Fuels-Utah Inc. approached the Bureau to assist in planning, installing, and evaluating a computerized mine monitoring and control system because of the agency's research experience in this area. The installation was planned for Western Fuel's Deserado mine, located in Rangely, CO. Since a large, complex, underground mine producing about 2.4 Mt/a (2.7 million stpy) of coal was projected, the company anticipated significant benefits in safety and efficiency through a computerized monitoring and control system. A major part of the cooperative program was to document and evaluate the system design, installation, and operation. This will assist others to adequately design, specify, install, and operate future systems. Mine description The Deserado mine plan and layout have important impacts on the monitoring system requirements. Long range plans are to produce 2.4 Mt (2.7 million st) of clean coal annually from two longwall sections and four continuous sections. Presently, two continuous miner sections operate under 213 m (700 ft) of overburden in the 2.3 to 2.5 m (7.5 to 8.5 ft) thick D seam to develop main, submain, and panel entries have developed for a longwall. These began operation in December 1986. Belt conveyors haul the coal from the mining sections to a 1.4-m (54-in.) belt located in the upper compartment of the slope. The lower compartment contains a hoist for men and material transport. From the slope, the coal moves to two 9 kt (10,000 st) raw coal storage silos, then to a 680-t/h (750-stph) preparation plant. After cleaning, a 5.5-km (3.5-mile) overland conveyor carries the coal to a clean coal slot storage and rail load-out facility. An electric locomotive then transports the coal to the Bonanza Power Plant in Utah. Allen-Bradley monitoring and control hardware and software controls the preparation plant, with two PLC-3 programmable controllers and a Process Control Industries D-1200 color graphics interface. The system operator uses three "smart" color video display units and an alarm printer for hard copy records. Originally, it also monitored and controlled the conveyors from the bottom of the slope to the top of the raw coal silos, the preparation plant, the overland conveyors, the main mine ventilation fan, and the hoist. Some of these features, though, were later transferred to the mine system.

Jan 2, 1988