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By S. M. Hsiung

Chain pillar design formula under weak roof condition was developed by statistically analyzing the results from the three dimensional finite element parametric analyses. The parameters such as mechanical properties of the roof and floor strata, overburden depth, panel width and length, and coal strength were incorporated in the formula. A conversion formula which transfers a rectangular chain pillar into a square chain pillar of equal strength is proposed. The influence of high in-situ horizontal stresses, which are often encountered in the coalfield, on chain pillar stability is also discussed.

Jan 1, 1984

By E. D. Sehnke

The refractory materials industry provides the largest commercial market for nonmetallurgical grade bauxite. Refractory grade bauxite is prepared from bauxites having low iron, titania, and alkali content by calcining at temperatures near 1,650° C. Although there are substantial bauxite reserves in the world, premium grade bauxite ores suitable for use in refractory applications are limited to only a few specific sources, primarily in Guyana and the People's Republic of China. Consumption of bauxite for refractory use is closely associated with the production and consumption of primary metals, in particular iron and steel. Barring major disruptions within the principal producer nations, sufficient supplies of refractory bauxite will be available to meet world demand well into the next century, and raw material costs will continue to determine the availability of markets for bauxite-based refractory products.

Jan 1, 1992

By Rushikesh Battulwar, Javad Sattarvand, Joseph Seamons, Masoud Zare

In the last decade, new developments took place in the area of indoor positioning (or localization). Since the Global Navigation Satellite System (GNSS) cannot be used in underground mines, other technologies are needed for localization. Positioning and communication options today primarily include Wi-Fi, Bluetooth Low Energy (BLE), Ultra-Wideband (UWB), Radio Frequency Identification Device (RFID), etc. Smartphones and tablets currently have an array of sensors and radios, which can provide valuable information to allow indoor localization via various methods. Where mineworkers could keep smartphones with them, they can be highly effective at enabling localization and navigation. Recent applications of these technologies in underground mines have been thoroughly reviewed and examined for the likelihood of their utility for accurate localization where no other means exist. Some critical challenges and gaps that need to be addressed in future research have been identified.

Sep 5, 2021

By J. Yuan

Ground calcium carbonate (GCC) and chemically precipitated calcium carbonate (PCC) have become important mineral-based commodities in recent years. GCC manufacturing generally requires high purity and high brightness deposits of marble, chalk or limestone as the stone source. PCC usually uses limes made from lesser quality limestone deposits. GCC products have a wide span of particle size, with a d50 size ranging from sub micrometers to as large as several inches such as those used in landscaping. PCC products are typically limited to less than 10 µm (1,250 mesh). Each PCC product has a narrowly distributed size range. GCC and PCC products tend to have higher levels of whiteness com-pared with other traditional filler and extenders, such as kaolin and talc. Published statistics of GCC production volume often vary due to the exclusion of certain size range GCC products. According to Roskill’s latest estimate, world GCC capacity was believed to exceed 56 Mt (62 millionst) during 2004 for all grades.

Jan 1, 2005

By Charles Stone, Eric Wang

A method for estimating geotechnical rock loads for shallow cut and cover subway stations is presented. Localized geotechnical conditions lead to extreme variations in rock loading on the walls of subway structures. Actual lateral rock stress on these structures can range from near zero to over four times the vertical in-situ rock stress. The primary factors affecting the actual lateral stress are intact and rock mass mechanical properties, excavation sequence, localized tectonic conditions, and potential future adjacent structures. The authors recommend using the AASHTO code value of 65 pounds per cubic foot (10 kN/m3) during concept design, followed by numerical analysis of rock wedges and stress measurement for final design.

Dec 1, 2022

By F. G. Miller

Over the past 30 years, the coal industry has been continually striving to perfect methods for cleaning fine coal to acceptable ash and sulfur contents while maintaining maximum product yield. The flotation process has been part of this effort and its importance is expected to grow as new utilization technology demands finer and purer coal products. The work outlined in this paper is part of a larger effort aimed at development of new and improved flotation systems for removing sulfur and ash from as-mined coal as well as for producing super-clean coal for future markets. The concepts and data presented are now serving as a basis for designing fine-coal circuits in which improved efficiency is obtained by optimum use of flotation.

Jan 1, 1986

By J. O. Marsden

Parts I and II in this series of papers presented the chemistry of medium-temperature pressure leaching of copper sulfide concentrates and reviewed the metallurgical development of a process to effectively recover copper using medium-temperature pressure leaching and direct electrowinning (DEW). Key features of the process were the use of superfine grinding of the concentrate (to a P98 of 12 to 15 µm and P80 of 6 to 7 µm), pressure leaching at 160ºC and 1,380 kPa (200 psi) oxygen overpressure, DEW to produce LME Grade A cathode, recycling of the lean electrolyte to the pressure leaching step and treatment of a lean electrolyte bleed by solution extraction (SX). Recycling of the lean electrolyte provided all of the acid required to effectively dissolve copper and convert approximately 65% to 70% of the sulfide sulfur to elemental sulfur, resulting in an ?acid-autogenous? process referred to as the ?MT-DEW-SX? process. This paper (Part III) discusses the steps taken to develop and complete a large-scale demonstration of the process at Bagdad, Arizona, in 2005.

Jan 1, 2007

By Xiaozhen Song, Ashish Ranjan Kumar, Shimin Liu

Diesel particulate matter (DPM) presents considerable occupational health hazards in large-opening underground mines (LOUM). Previous studies have primarily focused on single-factor ventilation optimization, while this study innovatively integrates booster fan configurations and loading truck placements utilizing a coupled CFD turbulence– particle tracing model. Three distinct ventilation scenarios were simulated to evaluate their effects on DPM dispersion and dilution efficiency. Results indicate that dual booster fans substantially enhance airflow distribution, increasing air exchange efficiency; The migration pathways of DPM closely align with airflow trajectories, and air turbulence is the predominant factor influencing particle behavior within LOUM; Loading truck placement critically influences local DPM accumulation; Airflow effectiveness diminishes markedly with distance from booster fans, causing stagnation at distant working faces. The coupled CFD approach accurately captured airflow–particle interactions, offering valuable insights for optimizing mine ventilation strategies and effectively mitigating miners’ exposure to DPM.

Feb 22, 2026

By Owens S. Roberts

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

Jan 1, 1971

By R. Unger, L. Mallett

The use of virtual reality (VR) technologies to train miners is an evolving area in research and development. In July 2006, representatives of 14 international organizations met to discuss current VR-related efforts and explore ways to employ VR in the future. This paper gives an overview of the various approaches presented at the meeting and discusses directions for future implementation. An example of a training package that teaches mine map-reading skills is presented. The meeting was the first step to building collaborations for furthering VR applications for mining. Planning has begun for a 2008 meeting open to broader participation.

Jan 1, 2007

By V. Kecojevic

The objective of this research was to establish the relationship between production, consumption and energy cost in the surface mining of bituminous coal. Specific energy sources such as diesel, gasoline, electricity, explosives and bituminous coal were considered in this study. Gain in net energy, proportion of the cost of energy consumption and total energy cost relative to total revenue of extracted coal were determined, and a new energy efficiency index and a new energy-cost ratio were established. A case study on an operating surface coal mine was carried out to demonstrate the application of the newly developed method. The results of this study can be used by the mine operators in establishing strategies for the optimization of energy production and consumption, and for reducing the cost of bituminous coal extraction.

Jan 1, 2014

By Laura McNally

In 2006 McNally International Inc. in a Joint Venture partnership with Aecon Constructors was the successful bidder on two York Region Tunnel Projects: Bathurst Collector/Langstaff Trunk Sewers; and YDSS Interceptor Sewer 19th Avenue Project. These projects comprise a total of 13 kilometres of 2.74 meter finished diameter tunnels and are both part of the York Durham Sewer System (YDSS). Both contracts require the use of EPB tunnel boring machines with a precast concrete segmental liner. The following provides an overview the two projects.

Jan 1, 2008

By Richard Belair, John Read

Ask someone what they can tell you about the Royal Canadian Mint and most likely the first thing that they will mention, is coinage. The Royal Canadian Mint manufactures Canada's one-cent coins, nickels, dimes and quarters - over 1 billion per year. Most of these coins use copper and nickel as base material, and all of this metal is mined, refined and processed in Canada prior to being shipped to the mint for coin production. In 1985 alone, 1270 metric tons of Canadian nickel and 2160 metric tons of Canadian copper were absorbed in circulating coinage. July 1987 will have marked the introduction of Canada's new one dollar coin, an important new addition to Canada's monetary system. The first phase of this program will consume about 2,235 metric tons of Canadian nickel in the initial production run. Annual requirements in subsequent years are estimated at 225 metric tons. The Royal Canadian Mint is also a major producer of circulating coinage for foreign countries. Since the state-of-the-art Winnipeg plant swung into full production in 1976 the Mint has struck more than 5.2 billion coins for some 35 nations around the world. 1985 sales have increased almost 6 fold over 1984. 1987 already shows commitments for a further significant increase in volume in this business. The use of Canadian metals in export to foreign nations as coinage adds still more to the Royal Canadian Mint's key role as a major market maker for Canada's mining industry. The success of the Mint in this realm can be directly traced to it's 75 years as one of the world's most important refiners of gold. Today, the Royal Canadian Mint is the largest refiner of gold in the Western Hemisphere, and the third largest, by volume, in the world. The R.C.M. hallmark on kilo bars, 100 troy ounce comex bars

Jan 1, 1987

By L. A. Bakhvalov

According to the practice of mining management in the system of industrial complexes, the Kazakhstan gold mines are part of the mine processing industrial concerns providing ore-mining and ore-dressing. The cycle technology of winning operations used at the mining of vein deposits in the mines of the industrial concern is mainly provided by the systems of scrapping, scipping and electric locomotion. At present the information and computer system, elaborated on the basis of the Maikain underground mine is intended for creation of the system of automatic operation for the industrial complex mines. The information and computer system includes: - parametres characterising the accepted technology of works; - the main parametres characterising the technical devices of operation and control ; - information about the material, technical and personnel resources available at the mine; - mining and geological conditions of the deposit; - the facilities of the subsidiary units, of the mine; - the direct parametres and technico-economical indices in which the mine efficacy and activity is estimated. The suggested structure of the automatic operation system can be sensibly realized with the application of the microprocessor on the first level, the personal computer IBM PC/XT or PC/AT on the second level. For the complete realization of the project each mine will need 4-5 computers (as PC/XT), one IBM PC/AT and each mine complex - one super IBM for creation of the distributed information bank and its including in the integral world communication system.

Jan 1, 1992

By W. G. Pariseau

This contribution describes rock mechanics features of the Davis Cavern at the former Homestake Mine in Lead, South Dakota, U.S.A. The mine is located in the northern Black Hills of South Dakota. In 2003 and again in 2008, the mine site was recommended for development as a national Deep Underground Science and Engineering Laboratory (DUSEL) in cooperation with the Sanford Underground Science and Engineering Laboratory under the South Dakota Science and Technology Authority (SDSTA). The original Davis Cavern was excavated about 9.1x16.8x9.7 m high (30x55x32 ft high) in 1965 (Mitchell 2009) at a depth of 1,478 m (4850 ft). The purpose of the cavern was to house apparatus for detecting solar neutrinos. The experiment ultimately proved successful and earned R. Davis a share of the 2002 Nobel Prize in physics. Recently, a new experiment (LUX=Large Underground Xenon detector for dark matter particles and WIMP's=weakly interacting massive particles) was proposed for the Davis Cavern that required an increase in height of 2.4 m (8 ft). For many years, the Homestake gold mine was the deepest operating mine in North America. Development extended to the 8000 Level (2,438 m). The mine closed in 2003. Pumps were shut off and the water level rose to the 4350 Level, about 150 m (500 ft) above the Davis Cavern. Some six years later after selection for DUSEL proposal development by the National Science Foundation (NSF), access to the 4850 Level and the Davis Cavern was regained. Pumping has lowered the water level to well below the cavern floor. Figure 1 shows the layout and location of the Davis Cavern (Cavity). Detector tank, supporting steel, and so forth were subsequently removed. The cavern was re-supported and new access was developed. By August, 2010, 13,000 ft3 had been removed during enlargement and renovation of the Davis Cavern. Figure 2 shows the detector tank under construction in 1965.

Jan 1, 2012

By İbrahim Çınar, Hakan Özşen

Mine workers in heavy and dangerous work are under several physical risk factors, for example temperature, humidity, noise, vibration, lighting and air velocity. Thermal comfort includes parameters such as air temperature, air humidity, air flow rate, radiant heat, metabolic rate and garment insulation. In this study, thermal comfort conditions were evaluated using thermal comfort indices defined as predicted mean vote (PMV) and predicted percentage dissatisfied (PPD) which were determined by measurements taken from an underground coal mine for approximately 100 days. Although the metabolic rate (light work) was kept at 2 met, it was found that predicted mean vote ranged between − 2.58 and 1.68. The predicted percentage dissatisfied index was found to reach 95%. According to the results, it can be seen that thermal comfort may have negative effects on occupational health and safety. The change in thermal comfort index values in the Soma Underground Coal Mine was investigated in detail and the reasons for the changes were determined. Furthermore, determining the optimal working environment for the mine workers was also an aim of this study.

By William A. Rehrig

During recent years, there have been frequent investigations on the geochemistry of biotite. This work has emphasized, and no doubt was prompted by, factors related to mineral exploration, particularly for those deposits of the porphyry copper type. A large number of papers have been devoted to the obtainment of trace-element data from plutonic biotite. These data have been used to extract primary geochemical information pertaining to the parent magna and the hydro-thermal system which together give rise to porphyry copper deposits. In two early works, Putman and Burnham (1963) and Parry and Nackowski (1963) analyzed base metal contents of ferromagnesium minerals, primarily biotite, from various barrenfmineralized plutons of the Basin and Range Province. One similar conclusion from the two studies was that the Cu, Zn, and Pb contents of magmatic biotite served as indicators of ore development within the granitic rocks genetically related to ore. This theme was then pursued vigorously by a number of authors until the present time. Results, however, have been contradictory, as reviewed by Coope (1974). For example, studies by A1 Hashimi and Brownlow (1970), Lovering et a1 (1970), Putman (1972), and Graybeal (1973) continued to support positive primary relationships between the trace-metal content (usually copper) of biotite and associated sulfide mineralization. By studying biotite in close spatial association will sulfide occurrences, Putman (1972) and Graybeal (1973) developed models for base metal partitioning in magmatic systems based on their discovery of inversely distributed copper between silicate (biotite) and sulfide phases. Conversely, research by Bradshaw (1967) and Blaxland (1971) plus the recent findings of Parry and Jacobs (1975) and Kesler et a1 (1975) found little if any evidence to support a correlation of biotite base-metal or

Jan 1, 1976

By Garry Biles

The Eskay Creek Mine is a high-grade gold and silver underground mine in northwestern British Columbia. The mine started operations in late1994. For the first three years, ore was crushed to -50 mm(-2 in.), blended to satisfy smelter terms and shipped to smelters in Japan and Canada. Preliminary evaluations indicated that a complex metallurgical facility, requiring a large capital investment, would be required to recover the precious and other economic metals. So markets for raw ore were identified and underground mining and ore transportation operations began at a production rate of 300 t/d (330stpd).

Jan 1, 2000

By B. H. Kim, S. J. Schatzel, K. M. Ajayi, G. S. Esterhuizen, D. W. H. Su, Z. Khademian

The stability of shale gas wells drilled through current and future coal reserves can be compromised by ground deformations due to nearby longwall mining. Depending on the longwall-induced rockmass permeability, the high-pressure explosive gas from the damaged well may reach mine workings and overwhelm the mine ventilation systems. This study uses geomechanical models to estimate the rockmass permeability induced by mining. A two-panel longwall model of a deep, 341-m-cover mining site in southwestern Pennsylvania is constructed in 3DEC to explicitly model the rockmass by a Discrete Fracture Network (DFN) technique. Stress-induced fracture apertures and permeabilities are calculated across the model and are validated against permeability measurements. A Fracture Flow Code (FFC) is developed to use these results to predict potential inflow to the mine should a gas well breach occur. One hundred DFN realizations are simulated, and the results show that for a gas pressure of 2.4 MPa, the average of the predicted inflow rates to this deep-cover mine is 0.03 m3 /s, significantly lower than the average inflow of 0.92 m3 /s for a shallow-cover mine (145 m deep) studied in the previous work (Khademian, et al. 2021). The result can help assess the potential hazards of a shale gas well breach for mine safety and evaluate the ventilation requirements to mitigate the risk

Mar 2, 2022

By Michael F. Roach, Joseph K. Cavey, Gary E. Taylor

A rigorous horizontal drilling and chemical grouting program was specified beneath the Hollywood Freeway (U.S. Route 101) section of Los Angeles Metrorail Contract C-311.Twin 6.67-m (22-ft.) diameter starter tunnels were to be conventionally mined through amixed alluvial and bedrock face consisting of silty sand, gravel, and weathered sandstone and siltstone of the Topanga Group. The contact between the alluvium and bedrock dipped toward the Crossover Excavation where the horizontal drilling and grouting operations were performed. The intent of this grouting program was to stabilize the mixed face to minimize ground loss and surface settlement, and to reduce groundwater inflow into the tunnel headings. Given the highly variable mixed face conditions, horizontal drilling up to 86 m (284 ft.) resulted in upward trending trajectories which likely followed the bedrock contact. Chemical grouting was performed in a primary, secondary and tertiary, three dimensional sequence. Evaluation of the primary and secondary grouting parameters indicated where tertiary grouting was required. Grouting pressures induced a small rock failure at the tunnel heading as well as increased stresses on the tiebacks of the excavation.

Jan 1, 1997