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By N. P. Reddy

This paper describes an experimental setup for multiple-fan ventilation systems at the ventilation laboratory of the WVU Department of Mining Engineering. Housed in a 30 ft by 70 ft room, the experimental setup consists of three 18 in. variable-speed axial-flow fans, the 18 in. diameter fiberglass tubing and fittings for arranging networks, and the pitot tube measuring and data acquisition system. The fiberglass tubing and fans can be organized into the non-planner network of two fans or three-fans. It is mainly designed for studying the characteristic curves, operating points, and fan stall for the multiple-fan ventilation system.

Jan 1, 1992

By G. Deschênes

Silver minerals are known to have slow leaching rates and low overall extraction and require a high concentration of cyanide and a long retention time to maximize leach extraction. Their response to cyanidation is considered mild to moderately refractory, largely due to complex mineralogical compositions. New research on improving the dissolution of silver minerals in cyanide was performed using high-purity minerals, as well as a high-grade ore sample from the Kupol property, owned 75% by Kinross Gold. The high-purity silver minerals studied in the leach investigations included acanthite, stephanite and pyrargyrite, which were also the predominant silver minerals in the Kupol ore sample. Dissolution of silver from acanthite produced only 37% extraction in 48 hours of leaching with 500 ppm NaCN. Analysis of the leached acanthite surface showed appreciable formation of polysulfide species, which can interfere with silver leaching. Adding lead nitrate into a pretreatment stage increased the acanthite silver extraction to 86.2%. No polysulfide species were formed with the addition of lead nitrate from the surface analysis. Cyanidation of stephanite and pyrargyrite produced very low dissolutions of silver, only 12.6% and 10.4%, respectively, in the absence of lead nitrate. Silver extraction from stephanite improved to 98% by adding lead nitrate directly to the leaching stage, whereas pyrargyrite required a pretreatment with lead nitrate to extract 83.2% Ag. With the addition of lead nitrate, the mineral surfaces had a PbO species and minor amounts of Pb(OH)2 and antimony was oxidized on the stephanite and pyrargyrite surfaces during leaching. There was a much greater concentration of Sb(V) on stephanite relative to pyrargyrite. Therefore, lead forms a redox couple on silver mineral grains and favors the oxidation of silver minerals. The high-grade Kupol sample assayed 22.6 g/t Au and 359.3 g/t Ag following treatment by gravity separation. Gold and silver extractions from the Kupol sample were 94.5% and 82.9%, respectively, using 500 ppm NaCN and 250 g/t lead nitrate. The findings to improve the extraction of silver from the ore sample with lead nitrate addition were congruent with those to improve the extraction of silver from the individual high purity minerals. Pretreatment did not, however, improve gold or silver extraction significantly with the ore sample.

Jan 1, 2011

By R. S. Farinato

Thionocarbamate flotation reagents have enjoyed a niche position in the recovery of copper sulfides and activated sphalerites since their introduction in the mid 1950's (Harris, 1954). Thionocarbamates containing an allyl group (-CH2- CH=CH2), introduced recently Lewellyn, 1985; Nagaraj, 1988; Avotins, 1991), are used commercially as collectors for copper sulfides and activated sphalerite. Laboratory flotation tests and plant usage have demonstrated that allyl-containing thionocarbamate collectors exhibit certain unique properties that distinguish them from the corresponding dialkyl thionocarbamates. Spectroscopic (FTIR, XPS) and wettability studies of N-allyl iso-butyl thionocarbamate (AIBTC) and its saturated analog N-propyl iso-butyl thionocarbamate (NPIBTC) adsorbed on copper at pH 9 were performed in order to investigate whether there were any fundamental reasons for these differences. Flotation tests were carried out on chalcocite, copper ore and an activated sphalerite.

Jan 1, 1993

By Jerry C. Tien

Changes and the pace of change in China’s coal industry have been extraordinary during the past several years. At least 35 of the 94 former coal bureaus have been restructured into different mining companies and groups. Some of the more productive and efficient ones were further strengthened through consolidation and expansions. And several have even formed, or are in the process of forming, strategic alliances with utility companies, railroads, ports and chemical companies to secure additional reserves and coal sales. In addition, the improvement in coal pricing during the past two years has enabled China’s coal industry to move ahead with some needed changes. Coal mining accidents, though, remain a major concern for the Chinese government. Accidents remain high even though the government has made efforts to shutdown more than 55,000 unlicensed, unsafe small coal operations throughout the country.

Jan 1, 2003

Refractory copper ores (CROs) in central Africa contain copper minerals that are locked up in a micacious solid matrix or associated with carbonate, sulfide and phosphate minerals. Several researchers have reported that the recovery of copper from CRO material by an acid-leaching process is not economically feasible, due to the presence of excess gangue-acid-consuming minerals such as calcites, dolomite, asbolane and iron oxides. Since the proportion of acid-insoluble copper (CuS) is about 28% of total copper and total free sulfur is extremely small, sulfide flotation was considered unfavorable. Consequently, hundreds of millions of tons of CRO material have been stockpiled specifically at the Nchanga Mine of Zambia. In terms of copper distribution in CRO material, a significant portion of total copper exists as carbonates (39%) and oxides (17%), while 28% of the copper is acidinsoluble (CuS). The rest of the copper is in the form of carbonates (16%) and (hydr) oxides (17%). This means that only about 72% of total copper is recoverable through the non-oxidative acid-leaching process. In this study, batch leach tests were performed on CRO solids (d95 = 95%) to establish the gangue acid consumption values at different feed pH values and to evaluate the leaching characteristics of copper, manganese and iron within the CRO material. Subsequently, continuous leach tests were performed on CRO solids (106 um, 80% passing) using optimum leach conditions derived from batch tests. This paper aims to show that sustainable copper recovery can be achieved by selecting leaching conditions whereby gangue acid consumption (GAC) values become significantly small and the final concentration of manganese and iron in the leach solution are appreciably low.

Nov 1, 2011

By Terence P. McNulty

Gold-bearing outcrops were discovered in 1862 by Union soldiers garrisoned at Needles, CA, near the northwest corner of the future State of Arizona. Sporadic mining began several years later, but engineered shaft sinking and mill construction were not adopted at Oatman and the neighboring camp of Goldroad until about 1900. Geological interpretations in 1915 enabled major production during the next decade. In the late-1930s, USSR&M built a new mine and mill in Gold Road and the District flourished until closure by Federal Order L-208 in October 1942. For about a decade, Oatman’s mines were among the largest gold producers in the American West.

Feb 1, 2024

By Shahab Alizadeh, Ahmad Khodadadi Darban, Mehdi Mohseni, Mahmoud Abdollahy

This study probed the selective separation of lanthanum and yttrium in a nitrate medium in the presence of aluminum and calcium impurities using di-(2-ethylhexyl) phosphoric acid (D2EHPA). The factors studied in a central composite design (CCD) included extractant concentration, pH, concentration ratio of total impurities to rare earth elements, and interaction of these three factors. The extraction mechanism and types of extracted metal-containing species were delineated by the slope analysis method. The obtained thermodynamic data showed that lanthanum and yttrium extraction by the D2EHPA extractant was exothermic. The extraction of both rare earth elements was accompanied by an entropy reduction. The negative magnitude of ΔS in yttrium extraction reaction suggests stronger D2EHPA-Y(III) complexation relative to La(III). As entropy decreased and enthalpy increased, the extraction process became unspontaneous. Using the proposed flowsheet, lanthanum and yttrium products with > 90% purity were obtained.

Aug 10, 2021

By Z. Henderson, J. R. Saylor, L. Rojas-Mendoza

"Diesel particulate matter (DPM) is a major occupational health hazard in underground mine environments, even with available abatement technologies. Prior work has demonstrated that micrometer-scale water droplets, or “fog,” may be effective in removing significant number fractions of DPM from a conditioned exhaust stream. Here, a series of laboratory experiments are described which demonstrate that such a treatment can remove significant DPM mass from an unconditioned stream. The removal mechanism involved coagulation of the DPM and drops. The fog treatment removed about 45 percent more DPM mass on average than no treatment. Varying engine load, flow rate and fog droplet number density did not significantly affect the results under the range of conditions tested. IntroductionDiesel engines have seen widespread use for well over a century due to their relatively high thermal efficiency and fuel economy (Heywood, 1988). Recently, however, the adverse health risks of diesel exhaust have become increasingly clear. The term diesel particulate matter (DPM) is used to refer to the solid components of diesel exhaust, which are an ultrafine mixture of elemental and organic carbon (EC and OC) and minor constituents including sulfates and metal ash (Kittelson, 1997). DPM is generally considered to occur almost entirely in the submicrometer range. It is classified as a carcinogen (Occupational Safety and Health Administration, 2013), and epidemiological studies have demonstrated a positive correlation between long-term exposure to DPM and other combustionrelated fine particulates and increased cardiovascular and pulmonary diseases (Pope et al., 2002; McDonald et al., 2011). Many of the risks of diesel exhaust are associated with the physical and chemical properties of exhaust components (Heywood, 1988; El-Shobokshy, 1994; Kittelson, 1997). Exposures are generally measured and regulated on the basis of mass concentration. However, DPM number density and particle size are increasingly recognized as critical factors in terms of health outcomes (Bugarski et al., 2012; Kittelson, 1997; Occupational Safety and Health Administration, 2013; Pope et al., 2002)."

Jan 11, 2017

By Jacob Carr, Bruce Whisner, Adam Smith, Jingcheng Li

Electromagnetic-based proximity detection systems (PDSs) are utilized on mining machinery to protect workers from being pinned or struck. These systems generate magnetic fields covering the space around a machine, and a miner-wearable component (MWC) detects the field. The PDS determines the distance of miners relative to the machine based on the detected magnetic flux density in the magnetic field. This information is used to establish warning and shutdown zones around the machine. Maintaining a stable magnetic field is essential for system accuracy. However, components used to generate magnetic fields can be influenced by temperature changes. Depending on ventilation conditions and seasonal alternation, a PDS can be subject to significant temperature fluctuation. To better understand and quantify this phenomenon, researchers from the National Institute for Occupational Safety and Health (NIOSH) developed an experimental apparatus to study the influence of temperature on magnetic field generator circuits used in PDSs. Results from the study show that the electric current through a generator can be influenced by both ambient and internal temperatures, modifying the magnetic field that is produced. These findings show that temperature can significantly influence the ability of PDSs, used in underground coal mines, to accurately determine a worker’s position in relation to mining machine.

By Jose F. T. Agapito

The mining engineer must be able to predict the structural behavior of the rock around underground openings so that he can answer questions relating to safety and economics. With the present status of rock mechanics knowledge, exact predictions cannot be attained and approximate idealizations are made. As a first approximation, structural design makes use of theory, laboratory testing of rock properties, and available experience from excavations in similar rock formations. However, realistic design can usually be obtained only after in-situ observations and measurements are made. After all the information is collected, judgement and experience play a most important role in the final formulation of the design. This paper describes part of a geotechnical program which was instrumental in obtaining information for the design of large oil shale pillars. The work was carried out during 1971 and 1972 in the experimental mine of the Colony Development Operation. Colony is an oil shale venture formed between Atlantic Richfield Company, Operator, The Oil Shale Corporation, Cleveland-Cliffs Iron Company, and Sohio Petroleum Company to conduct research and development in mining and retorting of oil shale, The property is located in the southern edge of the Piceance Creek Basin in northwestern Colorado, approximately 250 miles west of Denver (Figure 1) . Mining was conducted by the room-and-pillar method in a 60-ft high portion of the Green River Formation at a depth of 600 to 850 ft, Pillar dimensions are approximately 60 ft by 60 ft. The mine site is in the eastern face of the canyon containing the Middle Fork of Parachute Creek, The distance from the mine to the side of the mountain varies from 500 to 1,200 ft, and its height above the stream floor is approximately 700 ft.

Jan 1, 1974

By Louis W. Towle

A brief history of the use of Ammonium Nitrate in explosives and blasting agents is given. Methods of manufacture and physical properties of the various types of Ammonium Nitrate are given with particular reference to their use in blasting agents Important properties of blasting agents discussed are sensitiveness, methods of initiation, velocities of detonation, strength, density, products of detonation, rate of pressure development, and borehole pressure.

Jan 1, 1959

By D. U. Gustafsson

After half a million meters drilled with Wassara we are now confident that ITH hammers powered with simple water will become an established product for production drilling. Today four drill rigs in LKAB Malmberget equipped with Wassara drill about 25 000 m per month of 4 1/2" holes. In Kidd Creek, Canada, Was sara is used for production drilling in stopes with good results. The first Wassara 6" hammer has drilled a 36 meter long, completely straight horizontal cut hole for drifting in the LKAB Malmberget Mine. Main advantages are about doubled penetration rate, very good air quality and improved hole cleaning which facilitates stabilized drilling. Disadvantages are resistance to new technology and, in some cases, the increased use of water.

Jan 1, 1995

By P. R. La Pointe, H. C. Ganow

The production of both over- and undersized coal fragments is a constant problem to open pit operators in the Powder River Basin. Operators strive to achieve production blasts that economically minimize the weight percentage of over- and undersize coal. However, natural fractures influence blast fragmentation, and can impose limits on the final fragment size distribution. ARCO&apos;s Anaconda Minerals Company studied the limits placed by natural fracturing as part of a wider geotechnical study of the Wyodak Coal in the eastern Powder River Basin, Campbell County, Wyoming. Measurements of fracture orientation, size and spacing were made at ARCO&apos;s Black Thunder Mine. These data were used to form statistical distributions for natural fracture size, spacing and orientation. An algorithm was created to select fracture properties at random from these distributions and to form hypothetical blocks. The blocks were then numerically "sieved" to derive pos- sible particle size distribution curves. These curves are compared to fragmentation results from samples taken from three test blasts. All test blasts yield very similar lognormal fragment size distributions. The median particle size varies from 1.25 to 2.0 in.(3.2 to 5.1 cm), the mean from 4.0 to 8.5 in. (10.2 to 21.6 cm). The standard deviation was about 1.6 in. (4.2 cm). Coal fines (fragments < 0.25 in. or 0.64 cm) are about 15%. Calculated fragment distributions for the natural fractures predict the median size well but underestimate the variance. Algorithm modifications to account for processes known to occur in the comminution zone near the blast hole significantly improve the match in the fine coal size range. The match suggests that spacing of fractures, rather than fracture length, controls the formation of fine- and medium-sized fragments. On the other hand, the oversize coal is controlled by the fracture lengths, rather than the spacing. Data from subsequent test blasts support this idea. By increasing delay times from 8 msec to 17 msec, engineers were able to reduce fines to 7% - 10% but could achieve no further improvement, despite changes in shot pattern geometry, decking and hole size. The hypothetical fragment distributions show that, even without blast enhancement, about 5% of the natural coal blocks are fine-sized.

Jan 1, 1986

The Mine Safety and Health Administration (MSHA) has conducted studies to evaluate dust control technologies on deep cut continuous mining sections. These surveys have been conducted in different mines using various mining methods, face ventilation systems and dust control systems. The surveys typically consist of respirable dust sampling combined with a time study of mining activities. Measurements of dust control and operational parameters are also made. Critical elements identified for controlling respirable dust in deep cut mining systems include controlling intake dust, dust collector capacity, face ventilation quantities and velocities, positioning of workers, work practices and selection of equipment. This paper discusses how the dust surveys are conducted in deep cut mining sections and how these surveys are used to identify specific dust generating sources.

Jan 1, 1999

By Jamal Rostami, Mark Board, Clayr Alexander, Muthu Vinayak Thyagarajan

In the past several decades, many major equipment manufacturers have ventured into developing new technology for underground hard rock excavation. This includes variety of configurations for full and partial face mobile excavation units. Mining industry prefers machines that can excavate noncircular, flat invert profiles and be able to make tight turns in hard rock. The need to use disc cutters for cutting hard rock has impeded the development of such machines due to the need for gripper system or large mass of a machine to support the force requirements of the disc cutters. Most of the prior attempts have been partially successful and the operations have faced some practical limits and challenges. Among the units that have been successfully used, one can name mobile miner, which was used for rock excavation in some projects. A redesigned mobile miner, called the “Remote Vein Miner,” or RVM, has been developed by Epiroc for underground hard rock mining in Hecla’s Lucky Friday Mine. This equipment potentially opens numerous opportunities for innovation in civil tunneling projects, where the operational flexibility and accessibility of a TBM’s limited tunnel path, design of the profile, and cost are limiting factors. This paper explores the application of the RVM in tunneling projects, its advantages and possible areas of innovation in tunnel planning and design.

Jun 13, 2021

By S. M. Woodring

Research objectives included 1) determine relationships if any between spectral response of soil and soil textural groups, Unified Soil Classification subgroups and selected landforms and 2) develop computer assisted techniques for engineering soils mapping of remotely sensed data. The sire in northeastern Kansas, 1.6 Km by 43 Km (1.0 mi by 27 mi), contained glacial and alluvial soils. Multispectral scanner data (0.40 to 1.80 pm) collected at 915 meters altitude (3,000 feet) were analyzed using two distinct computer techniques: the nonsupervised approach involving delineation of soil training areas directly by computer and the supervised approach entailing training area selection manually by the researcher. Computer classification of surface materials follows both methods. Non supervised analysis results failed to show a consistant relation- ship between landform type and soil spectral class. Landforms correlating well displayed either unusually bright or unusually dark spectral signatures. Supervised analysis results showed a strong relationship between soil texture and soil spectral class. A moderately strong tie was shown between engineering soils groups (ML, CL, CH and OH) and their respective spectral classes, and a weak association between landform type and soil spectral class. An analysis procedure for engineering soils mapping by computer of remotely sensed data was developed. 1. Locate cultural features by visual examination of imagery. 2. Produce generalized bare soil-vegetation- water map using nonsupervised technique. 3. Outline significant soil fields for computer training using supervised approach. 4. Computer-classify entire area based on these soil fields.

Jan 1, 1974

By R. D. Hansen

This paper discusses the influence of frother type and dosage on recovery/selectivity in coal/sulfide mineral flotation as a function of particle size. It is shown that different frother structures do exhibit quite different but consistent performance characteristics depending on the underlying particle size ranges involved as well as the dosage levels of both the frother and collector. The data presented on existing commercial frothers end some new special purpose experimental frothers is used to illustrate some general operator guidelines on proper frother selection and use.

Jan 1, 1985

By R. Day

Nahcolite is a naturally occurring sodium bicarbonate mineral found principally in the Piceance Creek Basin of northwest Colorado. An 8-m thick nahcolite bed, 610 m below the surface, is the target of this first commercial nahcolite mine. A chamber and pillar mining system is developed by solution mining parallel 8-m tall by 18-m wide by 450-m cavities initiated along horizontally drilled holes. Hot water leaching, cooling crystallization and flash drying is the process. The sodium bicarbonate product is consumed by the baking, animal feed, industrial and acid rain abatement markets. A project overview, emphasizing the combination of horizontal drilling and solution mining technologies, will be presented.

Jan 1, 1994

By Gordon Hubbard, John D'Acierno

The Randgold Resources Ltd. mine operation in Syama Mali performs whole ore roasting followed by CIL gold recovery to produce gold. The roaster has operated continuously since the plant was first commissioned in 1994. The roaster design throughput is 216 tons per hour (5,184 TPD). Roasting provides for the oxidation of the· refractory components, organic carbon and sulfides. The energy balance for the system requires auxiliary fuel oil to be burned in the Circulating Fluid Bed (CFB) reactor. Energy from the 1200-1350 degree F roasted product stream is recovered and recycled back into the CFB using two fluidized bed coolers; one to directly heat the secondary air and the other to indirectly heat the primary fluidizing air. The basis of the design for the roaster was an extensive pilot plant test program, the results of which were scaled up to the full scale plant design. Due to variation in the feed at the mine a number of roaster modifications were necessary following the initial plant start up. During 1998 ore flotation capability was added to reduce the operating cost for the roaster and increase plant throughput.

Jan 1, 1999

By R. L. Derick

On a regular basis, mine personnel should obtain air samples directly from active underground areas as well as remotely from sealed locations. These samples provide mine officials with data relative to the makeup of the various atmospheres. Should conditions underground change, these results can provide a baseline that can assist officials in determining the extent of change. Relating the concentrations of individual gases to time, applying gases to equations, and examining their change over time are tools that have been successfully used to determine if a heating event exists and, if so, the extent of the emergency. These atmospheric status equations have either been developed for the mining industry or adapted from other industries. They serve as tools to assist personnel in determining the condition of underground mine atmospheres. As long as the problem area continues to be ventilated, certain gases, gas ratios, and equations can be used to determine if a fire exists, what type of material could be burning, and what quantity of coal is burning. Once the mine or the involved section has been temporarily sealed, gases, ratios, and gas-derived equations can assist personnel in determining how conditions within the sealed volume are changing over time. To alleviate potential explosions when fresh air is once again introduced into the sealed volume, equations and a diagram have been developed to predict the likelihood of an explosive atmosphere. Similarly, prior to commencing recovery of a mine or section, equations exist that can assist in determining if the fire will rekindle when air is reintroduced. This paper serves as an overview to remind and/or instruct readers about gas-sampling methodologies and gas analyses to assist in determining the status of underground atmospheres.

Jan 1, 2006