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By Thomas Novak, Sampurna Arya

Controlling dust generation and keeping it below permissible limits to meet federal dust standards at the working face of a roomand-pillar coal mine is a challenge for a mine operator. With the recent changes in federal dust regulations requiring lower worker exposure, maintaining compliance has become increasingly difficult. The current most effective practice of dust control at a continuous miner face in an underground mine is the use of a flooded-bed scrubber. A study carried out by the National Institute for Occupational Safety and Health (NIOSH) indicated that a flooded-bed scrubber could achieve cleaning efficiencies between 58 and 90%. But, the operation of such a system is maintenance intensive. The flooded-bed scrubber screen becomes clogged with dust particles and requires frequent cleaning to maintain performance. However, the dust control issue is not solely a mining industry problem. Other industries face similar issues. The University of Kentucky collaborated with Toyota Motor Manufacturing on the development of a novel wet scrubber, called the vortecone scrubber, for capturing oversprayed paint particles in automotive paint booths. The vortecone scrubber achieved a cleaning efficiency of 99% and required minimal maintenance. This study aims to assess the ability of this vortecone scrubber to capture respirable dust in an underground coal mine. The paper presents the results of computational fluid dynamics (CFD) modeling of this vortecone scrubber. It discusses the effects of air quantity and dust particle size on the performance of the scrubber.

By George A. Komadina

Pima Mining Company has recently completed their expansion tripling the plant capacity to 18,000 tons per day and now is in the process off expanding to 30,000 tons per day with completion scheduled for the summer of 1967. This paper briefly discusses the additions to the mining department and support areas with a more detailed report on the complete new crushing plant and additions to the concentrator. The crushing plant includes a 54-inch gyratory crusher, three 7-foot standard and seven 7-foot short head crushers along with necessary screens, feeders, and conveyor belts to produce a minus 1/2-inch rod mill feed. The concentrator consists of ten milling sections, each containing one 10-foot by 16-foot rod and two 10.5-foot by 13-foot ball mills, classification is done with cyclones. Pulp from each section is floated in 50 cells of 66-inch Fagergren flotation machines to produce a rougher concentrate which is cleaned in six stages of Denver cleaners to produce a final concentrate The various mill products are thickened with disposal made in conventional manner. Plant instrumentation is discussed in the paper.

Jan 1, 1967

By L. W. Laage

MFIRE is a mine ventilation and fire interaction computer simulation program. It allows transient state ventilation simulation and features mass based flow rates, natural ventilation, air recirculation, fan curve fitting, airflow reversal and product of combustion tracking. MFIRE was designed to accommodate the needs of the mining industry for routine ventilation calculations and mine emergency planning. This paper describes recent work by the Bureau and MTU to improve MFIRE by incorporating humidity in the mass flow and heat exchange calculations, a data file preparation program and variable reference density in the network calculations. Recent bug fixes are also discussed.

Jan 1, 1993

By Erik Westman, Brandon Stables, Benjamin Mirabile

"Standing support is often used in conjunction with underground retreat mining. Knowledge of the load-displacement behavior of standing support and loading induced by the mine opening is critical to proper support selection. The NIOSH STOP database contains load-displacement laboratory test data for most commonly used standing supports. Hydraulic load cells currently used to measure in-situ loading of standing supports have exhibited leakage under load, producing irregularities within the dataset. An improved hydraulic load cell eliminates leakage and produces more consistent data.INTRODUCTIONA hydraulic load cell, more commonly known as a flat jack or JackPack, is a device installed to determine the loading characteristics of the roof-to-floor supports. These standing or roof-to-floor supports include, but are not limited to pumpable cribs, cans, wooden cribs (4-point, 9-point, etc.), metal props, wood timbers, concrete donut cribs, and other variations of these standing supports.Flat jack devices have been used previously to determine the loading of such roof to floor supports. The most commonly used load cell for standing supports is based on a design intended for pre-stressing standing supports, not load measurement. Preloading helps to keep the supports, such as timbers props and cribs, in place during the dynamic loading associated with blasting (Barczak and Tadolini, 2004).Flat Jacks are manufactured in various shapes and sizes depending on the application; common shapes are square and round that are 25.4 mm (1.0 inch) thick when collapsed, as shown in Figure 1. These load cells are produced in South Africa and can be formed into several different shapes depending on the application (Barczak, 2003). The sheet metal that makes up the bladder is comprised of 19-gauge or 1.11 mm (0.04 inch) thickness; the top and bottom pieces of sheet metal are resistance-seam welded around the perimeter. There are two different ports installed on one of the bladder skin corners of the flat jacks; these ports allow fluid to fill the unit, and the other port has a relief valve. The fill port is comprised of a check valve. The pressure relief valve is located in the second port; preset to 1,724 kPa (250 psi), the pressure relief valve keeps the load cell from bursting. Bursting of these load cells typically causes a small tear in the metal skin allowing the fluid to leak out without a large catastrophic failure.The effective inflation range of these load cells is between 25.4 mm (1.0 inch) to 254.0 mm (10.0 inches) thick. Different types of fluids can inflate these load cells but the most common and easily accessible fluid for testing applications is water. Water pressure from the mine supply line can inflate these load cells to the desired load. Depending on the pre-stressing requirements, a pneumatic powered pump, hydraulic pump, or hand pump may be required to inflate the load cells."

Jan 1, 2019

By Charles R. Boardman

Recent underground nuclear tests in tuff, alluvium, salt, and granite have yielded data essential to the evaluation of mining applications of contained nuclear detonations. The data indicate that for these media the cavity radius is predictable within ±20% without regard to the properties of the rock in the immediate shot environment. Properties of the chimney of broken rock resulting from collapse of the cavity, on the other hand, are found to be related to the properties of the rock and its preshot structural weaknesses. Seismic effects and radioactivity distribution are sufficiently documented to serve as a basis for predicting the safety conditions associated with detonations for a variety of yields.

Jan 1, 1964

The Colorado portion of the Rio Grande rift is clearly defined physiographically from the south in the San Luis valley northward to the latitude of Leadville where sediments of the Dry Union Formation (Tweto, 1961) accumulated within the subsiding rift zone. To the north of Leadville is a system of faults active in the late Tertiary, including the Mosquito fault that offset a portion of the Climax mineralization (Wallace et al., 1968). Tweto (197B) describes remnants of Dry Union Formation against the Mosquito fault north of Dillon in the Blue River valley, so it is apparent that the rift and associated sediments extended well to the north of Leadville. Kelley (1952, 1954, 1956) and Chapin (1971) have noted in New Mexico that the Rio Grande rift is a series of en echelon basins, offset to the east, with constrictions connecting them (Fig. 1). In Colorado the structural basins are offset to the west. The net effect of all the rift zone basins in New Mexico and Colorado is an arcuate pattern (Fig. 1) abutting the Colorado Plateau and Sari Juan Volcanic Province on the west. The width of the rift system gradually decreases northward to about Leadville where rift definition is not apparent.

Jan 1, 1987

By R. J. Sweigard

Estimated costs and revenues can be used in the evaluation of post- mining land use alternatives. However, post-mining land use decisions have to be made in an environment complicated by several additional factors. These factors, including cultural, natural, and managerial issues, are not as easily quantified as costs and revenues but may be more important determinants. There- fore, some approach is needed to attach relative weight to the various factors. The concept of fuzzy sets assembled into a structured hierarchy facilitates analysis of the relative value of individual factors and their impact upon each alternative under consideration. In this paper, a method is presented which employs fuzzy set analysis to evaluate postmining land use plans on the basis of these nonquantitative factors.

Jan 1, 1986

By Edward O. Reinbold

The paper presents the results of a study which involved collection and analysis of airborne pollutant concentration data in two producing underground room and pillar metal mines which use diesel powered equipment in the area near the face. The results include the concentrations of CO2, CO, NO, NO2 and respirable particulate matter measured with the latest portable instruments, and the carbon and hydrogen contents of the particulate matter samples determined by combusting them in a Elemental Analyzer. The carbon and hydrogen contents are used to estimate the amount of diesel particulate matter in the mine ambient air. The short term grab sample concentration data, although not suitable for determining compliance with ACGIH Threshold Limit Values (TLVs), are related to the TLVs so that they may be compared conveniently. Lognormal frequency distributions and the arithmetic mean of the concentration measurement data are used to compare different mine situations. Conclusions are drawn as to which pollutants are most important to control under actual mine production conditions.

Jan 1, 1979

By P. Kim Carroll, D. Nick Tiffany, Doyl M. Fritz

Thunder Basin Coal Company received the 1987 Wyoming Excellence in Surface Mining Award for construction of the State's first major sediment control reservoir to be designed using the new settleable sol ids standard. Use of this standard resulted in construction cost savings of more than $250,000; reduced water quality monitoring; enhanced downstream channel stability because of more natural sediment loading; allowed simultaneous establishment of permanent waterfowl and fisheries habitat; and provided a quality recreational site. This article will address factors associated with the design and construction of that sediment reservoir and the benefits that were realized. (Note: This paper was originally published in the proceedings for the 1988 National Symposium on Mining, Hydro1ogy, Sedimentology and Reclamation held in Reno, Nevada, December 5-9, 1988.)

Jan 1, 1989

By William O. Rasmussen

Exploration requires processing highly varying kinds and amounts of geologic information. Successful discovery dictates that this be done quickly with maximum confidence. Most phases of exploration are more or less applicable to computer reduction on a routine basis. The use of digital computers to reduce raw data into interpretable form, lets the exploration geophysicist concentrate on interpretation and presentation, and to consistently apply more sophisticated and comprehensive analytical techniques, not practical before. In applying these concepts for the past several years, various efficient programs have evolved which provide more complete evaluation of all data including the pro- vision for more unique solutions. This has resulted in greater refinement and ability to select the most advantageous drill sites in a minimum time at a minimum cost or, in rejecting as soon as possible a project on which additional effort is no longer justified. Practical examples of computer applications in magnetics (air and ground), induced polarization and resistivity are discussed.

Jan 1, 1969

By M. M. Veras, C. H. Sampaio, A. S. Young, D. Neto, C. O. Petter

"Due to new technological developments, automatic sensor based sorting has made progress within industrial minerals, precious metals, diamond, and coal mining in recent years (Lessard et. al. 2016). In order to re-introduce the technology to other mining sectors, this research discusses its application to iron, manganese, and zinc ores through test works performed by the authors. These test works were performed using Dual Energy X-ray Transmission (DE-XRT) sensor technology. In each case, pre-concentrations of the ore were created demonstrating the possibility to reduce waste material, energy costs, and water consumption while improving product quality of the ores. INTRODUCTION Sorting of mining ores is as old as mining itself (Salter, 1991). Sensor based sorting applications in coal mining began as early as the late 19th century (Louis 1928). New sensor technologies were developed and implemented sequentially for uranium, nickel, coal, and gold mining (Refining, 1949, Rose et al, 1950, Bloomfield et al, 1966, Clayton et al, 1987, Robben and Mosser, 2014). While these sensor technologies were developed decades ago, computational capacity to keep pace with the vast amount of information required utilizing the sensor technology did not arrive until recently (Lessard et. al., 2016). The sensor based sorting (SBS) process was effectively described by Salter and Wyatt in Minerals Engineering in 1991, and Wotruba and Harbeck in 2010 in the Ullmann’s Encyclopedia of Industrial Chemistry under Sensor Based Sorting. Both descriptions include the following key steps: 1. Presentation of the material or particles. 2. Examination or detection of the material or particles. 3. Processing or analysis of the data generated. 4. Physical separation of the material or particles by external means. Effective presentation of the material or particles is achieved when the sensor is capable of identifying each particle individually. This step requires that each fragment of the material be isolated, and it often involves acceleration of the material fragments by chute or mechanical means, as well as the spreading of particles by vibratory feeders (Salter and Wyatt, 1991, and Wotruba and Harbeck, 2010). The isolated particles typically are conveyed into an area wherein they are subjected to electromagnetic irradiation (except in cases of some radioactive ores), either in the form of x-ray, visible light, infrared, or other energies. A wide range of applications for sensor based sorting exists in the literature. The majority of applications fall into one of two camps, (1) pre-concentration of mineral ores, or (2) characterization of the material during processing (Buxton and Benndorf 2013). While there is much to be gained from in-line material characterization and the resulting control both of quality and processing, this article focuses primarily on the camp of pre-concentration of mineral ores."

Jan 1, 2017

By D. S. Dinsmoor

Boron, estimated to comprise about 0.001 percent of the earth's crust (Fleischer 10), as an element is never found free in nature, although its compounds are found in many localities. the borates are the most important. Sassolite (B(OH)3) and boracite (Mg6C12B1406), non-borates, are-of-minor importance. The crystal structures of most natural borates are still unknown. A classification based solely on the ratio of boron to the total number of cations has been devised (Palache 28). This classification divides the borates into four, sub-groups; anhydrous borates, hydrated borates, borates containing hydroxyl or halogen and compound borates. Only four or five minerals of the hydrated borates group have ever been used commercially. In more recent years, the sodium borates have comprised all but a 'small fraction of all borates used. Borax, the hydrated borate compound, is the most important of all boron compounds. It has been used so long and so often that the layman often confuses borax and boron and, applies the terms synonymously.

Jan 1, 1958

By Peter Johnson, David Barber, Lachlan Henderson

"Within underground portions of metro rail networks the traditional approach to a design fire has been to assume a worst credible railcar fire and develop ventilation and egress measures for life safety. This approach is being challenged as a rail network approach to design fires becomes a more practical and realistic approach. The network approach is based on utilizing an in-depth hazard analysis, to understand ignition and fire load sources in tunnels, above and below the floor of the railcar and within stations, and then utilizing a quantitative risk assessment to determine sets of fire scenarios. The process allows small, medium and large fires to be considered, with the consequences also being quantified. The selection of design fires has a significant influence on fire protection measures within a metro network and hence, is a major cost input. The rail network approach provides more robust decisions on fires, based on the hazards present. INTRODUCTION A fire within a rail car or one that occurs as part of a rail system can threaten the lives of users, maintenance staff and emergency services personnel. Fires in metro systems are rare events but can have severe consequences. As a result, any analysis of a potential fire must be thorough and rigorous and address not only regular accidents and small fires, but also very low probability, high consequence scenarios. The fire safety design process for a tunnel and station must start with the design engineers, contractor and operators making a number of key decisions related to fire protection measures, which may have significant cost considerations. One of the key aspects that influences the required fire protection is the design fire and the design fire scenarios, which is a key input for analysis. This paper provides an overview of the author’s experience in designing fire protection measures for rail networks in Europe, Australia and NZ, where a risk based framework is used to develop design fires and scenarios for the whole rail system – trains, stations and tunnels. This system wide approach is innovative, challenges the norms, but provides significantly more informed outcomes. The range of design fires will include small fires that may halt the network, larger fires for smoke hazard system design and significant post-flashover fires to assess the structural response."

Jan 1, 2016

At long last, mining is on the rebound in Minnesota?s Iron Range and the excitement is starting to show. The SME Minnesota Section?s annual meeting was once again held in the heart of Iron Range country, at the Duluth Entertainment and Conference Center on the Duluth waterfront. The conference boasted a record attendance of 475 people and its largest-ever trade show. Appearances by Governor Mark Dayton?s new Iron Range Resources & Rehabilitation Board (IRRRB) appointee, Tony Sertich, as well as a local Fox news crew (see clip on SME website [link: http://fox21online.com/news/duluth-mining-conference-breeds-optimism-tech-innovation]) made clear that a lot of eyes [ ] are on the industry as it dusts itself off from the 2008-2009 recession. While the early years of the 21st century were very good to the Iron Range, the global drop in commodities prices and production left many companies reeling and brought back bad memories of the collapse of the industry in the 1980s. However, two years of solid growth and a rebound to above pre-2008 production levels have let the Minnesota mining industry to relax a little and talk seriously about long-term growth and stability.

Jan 1, 2011

By C. Garcia, A. Potulska, J. J. Opazo, T. Comi

"The Sierra Gorda SCM sulfide ore processing plant began commissioning in the third quarter of 2014. Located in the Atacama Desert in northern Chile, the project is an open pit mine and Copper-Molybdenum processing plant is one of the most highly-instrumented operations in the world. It is the first hard rock operation in Chile and the second in South America to utilize HPGR technology. It is a significant Molybdenum resource especially in the first five years and the Molybdenum separation plant is complex. Designed to process up to 60 million lbs. of fine Molybdenum per year, it uses the latest technology and equipment to ensure superior recovery and product quality. It also has gas handling and alarm systems to fulfil the Company’s vision of “Zero Harm”. This paper discusses the overall operation and issues relating to the concentrator start-up. These include a review of the mineral processing design, the unified process control center and management information systems, and the correlation of geological and metallurgical performance data (mine-to-mill) for use in anticipating and preparing for treatment of diverse ore deliveries. INTRODUCTION Sierra Gorda SCM is a joint venture partnership with KGHM International (owned by KGHM SA, Poland), Sumitomo Metal Mining, and Sumitomo Corporation (Japan) operating in northern Chile. The Sierra Gorda open pit mine and Copper-Molybdenum processing plant will become one of the largest mines in the world. The need for optimum production efficiency and sustainability has driven the creation of the most modern, well-instrumented mine in Chile. This paper contains a general review of the project including geology and history. This was a very fast-track project going from greenfield site acquisition to mill start-up in 10 years. Highly-experienced and motivated engineers and technical staff have overcome many significant challenges resulting in a rapid ramp-up of production capacity. A potential expansion to double the production rate in the fourth year of operation has also been intensely studied. The Sierra Gorda property is located in the Atacama Desert of northern Chile, in the District of Sierra Gorda, Region II of Antofagasta, Chile (see Figure 1). There is almost no precipitation in this area. The mine site is generally flat with some rolling hills. The project is located about 5 km from the village of Sierra Gorda at an elevation of approximately 1,700 m above mean sea level. The village is near a highway and railway line. The city of Calama, home of the famous Chuquicamata Mine, is located about 60 km northeast of Sierra Gorda. In addition, the SG mine is in the midst of numerous other mines including Spence, Esperanza, Mantos Blancos, El Tesoro, Lomas Bayas, Gabriela Mistral, El Abra, Radomiro Tomic, and Escondida, to name a few."

Jan 1, 2015

By Mark A. Krall

The Conda Partnership's Dry Valley Phosphate mine is a thinly bedded, multiple seam, open pit mining operation where selective mining techniques are used to recover phosphatic shales. The mining methods used are truck/shovel and scraper/ dozer operations. The ore that is mined is shipped 32 km (20 miles) by rail to a beneficiation facility which upgrades the ore via washing and calcining. The mine and beneficiation complexes are owned by the Conda Partnership. The Conda Partnership is a joint venture between Beker Industries Corp. of Greenwich, Connecticut, and Western Co-Operative Fertilizers (U.S.) Inc. of Alberta, Canada. The Conda Partnership operates as a separate entity from the two partners.

Jan 1, 1984

By Robert Hochscheid

A patent issued to J.N.J. Leeman (1957) described the change in performance that takes place when a cyclone is installed in the horizontal position rather than the vertical position. Although this patent was directed more toward improvements that could be realized in the heavy medium cleaning of coal, it contained specific references to reducing the quantity of fine solids that would report in the underflow, and an example for fine sand classification is also included. The three cyclone installations for which data is given in this paper demonstrate that horizontal mounting of large cyclones can improve classification efficiency, eliminate some operational difficulties, and reduce cyclone maintenance requirements in closed circuit grinding installations. Cyclone Experience at Serrana S.A. Each of four grinding circuits at the Serrana S.A. de Mineracao Apatite flotation plant in Brazil have a 2.7 X 4.6 meter (9 X 15 foot) rod mill and each originally operated in closed circuit with two vertically mounted Model D20B (500m nominal diameter) Krebs Cyclones. New feed size is 25mm. The Apatite is liberated at a relatively coarse 35 to 28 mesh grind, but the 500mm cyclones had to be fed at 66 pct. solids in order to obtain an overflow analyzing 12 pct. coarser than 42 mesh. Because dilution water in the cyclone feed had to be limited, classification was inefficient, and there were other significant circuit difficulties as summarized in a recent article by C. A. Busnardo (1984):

Jan 1, 1985

By M. Gunter, M. Buzon

"Talc formed by hydrothermal alteration of preexisting carbonate rocks is known to be nearly monomineralic, and lacking in amphiboles. In southwest Montana, talc formed from hydrothermally altered dolomitic marbles, and is still actively mined. These talc deposits are typically in contact with quartzofeldspathic gneiss and marble. Accessory minerals vary between these rocks and the ore producing body; the identification and characterization of such minerals requires carefully selected analytical methods. Recent litigation and ensuing confusion over the petrology and asbestos content of these deposits challenges the talc mining industry in Montana, and elsewhere in the world. INTRODUCTION Commercial talc has been mined from the deposits in southwest Montana since the 1940s, and by 1956 the region had output 200,000 tons of talc ore (Chidester et al., 1964). Commercial talc refers to rocks containing more than 20% of the mineral talc (McCarthy et al., 2006); the ores from Montana typically contain upwards of 90% talc. This region remains the leading domestic source of talc in the U.S. partly due to the reserves in the area, and partly due to the diagnostic purity of the ore compared to that of other regions, some of which are no longer actively mined. The mineral talc, a sheet silicate, is expressed by the formula Mg3Si4O10(OH)2, and therefore can form in geologic environments that are rich in Mg, Si, O and water. The protolith for the talc deposits in southwest Montana is a dolomitic marble, but other common protoliths include ultramafic igneous, mafic igneous, and siliceous dolomites (McCarthy et al., 2006). Physical properties such as hardness of 1 on Mohs hardness scale, white streak and slippery feel are among some of the reasons why talc is so widely used as fillers in a number of industries. In decreasing order, ceramics, paper, paint, roofing, plastics, rubber, and cosmetics are the leading domestic industries that use talc despite the decreasing trend in U.S. talc use and production since 1994 (Virta, 2015). The purpose of this paper is to describe the mechanism of talc formation in southwest Montana by focusing on talc deposits and surrounding rocks in the Ruby, Greenhorn, and the Gravelly Ranges, and to relate the mechanism of formation to the composition of talc ores. The compositional data show mineral content of selected ores, and the major and trace element content of those minerals, specifically talc. Our electron microprobe (EPMA), powder x-ray diffraction (XRD) and x-ray fluorescence data for samples from five mines in these three ranges provide continued evidence of the purity of these ores despite claims made during recent litigation that these ores contain asbestos. The five mines that we discuss include the Beaverhead, Treasure, Regal, Willow Creek, and Yellowstone Mines (Figure 1.)"

Jan 1, 2016

By L. John Minnick

A revised and expanded edition of a previous paper** dealing with reactions of calcium and magnesium oxides and hydroxides with pulverized coal fly ash is presented. Lime-fly ash specimens were cured at constant temperature and subjected to X-ray diffractometry, differential thermal analysis, pozzolanic reactivity tests, and microscopical investigations. Bars of limefly ash were subjected to cycles of wetting and drying, and measurements of length change were recorded. A discussion of variations within and among types of lime and types of fly ash is presented. The nature of the pozzolanic reaction is reviewed, particularly as related to compounds which are used up and formed during the aging process. The relationship between the pozzolanic reaction and the resultant physical properties of the mixtures is examined.

Jan 1, 1968

By P. Kawahata

Newmont?s Twin Creeks Mine, located in northern Nevada, is producing gold ore from surface mining operations. The ore is currently processed at three different on-site facilities depending on ore type and grade. Processing facilities operate under stringent geochemical blending constraints that must be met from mine ore deliveries and off-site sourced ore. To analyze various strategic options, the technical team utilizes the mathematical optimization approach. However, due to the size and complexity of the operation, there are unique challenges in optimizing life-of-mine production scheduling. This paper describes those challenges and methods developed to take advantage of different scheduling software to effectively compensate each other and result in reasonable guidance. This paper also describes how those scheduling results are reflected in detailed mine plan and cost estimate work.

Jun 1, 2013