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By Timothy J. Orr, Jami M. Girard

A NIOSH study on occupational deaths between 1980 and 1989 indicated that in the United States, mining had the highest average annual fatality rate (3 1.9 per 100,000 workers) of any other major industry. Since "lack of training" was often cited as the primary cause of accidents, NIOSH has been investigating new methods for effective training. One such method is the use of low- cost, desktop computers to simulate a virtual mining environment. Computer-based training offers several advantages over conventional training because the computer programs provide a three- dimensional environment that allows the trainee to practice using evacuation routes, encounter mining hazards, and view mining operations without being exposed to any real danger. One major focus of the project is mine escapeway multiuser training using desktop virtual reality programs. Researchers have imported mine maps into the software for the purpose of practicing actual evacuation routes and procedures. Various scenarios for evacuation can be practiced in a three-dimensional computer simulation of the mine in a disaster situation, complete with smoke, fire, and other dangers. Depending on the trainee's job description (i.e., foreman, shift boss, beltman, etc.), certain tasks need to be performed in addition to navigating primary and/or secondary escape routes. Each scenario allows for individual or team-based training and provides a means to educate mine workers in hazard recognition and hazard avoidance. Using this program, mine workers can practice evacuating various mine layouts without the danger and expense associated with escapeway training in an actual underground mine. Each scenario can be changed to test the trainee's reaction in a variety of circumstances and run many times so the trainee can practice concepts. This training experience will help reinforce the knowledge acquired during more conventional classroom instruction, and the inherent flexibility of the program allows training materials to be tailored to meet the specific requirements of individual mines.

Jan 1, 2002

By J. B. Moritz

From the beginning, man has concerned himself with the task of controlling the elements and forces about him so as to provide a better and easier life. In the accomplishment of this task, he is required to utilize in the best way possible the resources which are available to him. In many cases, the available resources must bee refined before they are in a useable form. Many products in the mining industry fall into this category, as some form of refinement is generally needed to produce a saleable product. Over the years man developed more efficient ways of extracting the resources from earth through the use of electrical and mechanical devices. A reduction in manual labor, which is a by-product of increased efficiency through machines, has also been enjoyed. The combination of man's senses and new devices has also enabled man to reach a high level of control in the refinement process. Control of a process through machinery and man's senses has been termed an "art." Until recently man's senses (sight, feel) were the only method available for making measurements simply because suitable measurement devices (instruments) were not available. Even today some items cannot be measured and man's senses must be used. However, the development in our instrument laboratories tends to indicate that time will eliminate this. In recent years, control of many processes has been reduced to a science and part or all of the art eliminated. This does not imply that process art should be degraded; however, when a process is reduced to a science, uniformity of the product from day to day is attained. Decreased processing time and more efficient use of additives and raw materials are other benefits that result from control of a process when it is reduced to a science.

Jan 1, 1965

By J. A. Pontius

The Cresson Deposit is located in central Colorado within the historic Cripple Creek Mining District. The deposit has moved from its initial discovery in 1990 to full production in less than five years (current reserve nearly two million ounces). This accomplishment required a great deal of cooperative teamwork between the exploration, development, permitting and corporate groups. Nowhere was this cooperation more evident than in the construction of the geologic block model. The detailed modeling of gold and its metallurgical characteristics formed the foundation upon which critical financial and design decisions were based.

Jan 1, 1995

By J. L. Carr, A. K. Smith, C. C. Jobes, G. T. Homce

"Underground continuous mining machines pose a difficult safety challenge since their operators generally work in close proximity to these machines in very restricted spaces. Intelligent software for use with magnetic proximity detection systems has been shown to accurately locate workers around mining machinery in real time. Calibrating these systems requires the manipulation of a lot of data to determine the calibration constants. Researchers have developed software to analyze, convert, and visualize data acquired during this calibration process to more accurately model magnetic fields and their interaction with the environment. This paper details the background, development, and operation of the resulting application software focusing on the utility of the graphical user interface to visualize the magnetic field calibration data. The refined data developed by this process can then be utilized by the proximity detection system to more accurately identify the location of miners working in an underground mining environment. INTRODUCTION Roughly half of the electricity consumed in the United States is produced with coal, and roughly one-third of all US coal production comes from underground mines [1]. Over the last century underground mining health and safety has seen a continuous and dramatic improvement. However, machine-related injuries and fatalities continue to be a major safety concern [2]. Every year, hundreds of miners are severely injured while operating underground mining equipment, and 39 miners have been killed in striking/pinning accidents involving continuous mining machines (CMMs) since 1984. CMMs, such as the one shown in Figure 1, are large mobile machines that are used to mechanically cut coal in an underground mine. These machines weigh approximately 40 to 50 tons, have hydraulically articulated appendages, and are capable of moving at speeds up to six feet per second [3]. Modern CMMs are remote-controlled, yet the operator and other miners are often in close proximity to the machine. Recent research by the National Institute for Occupational Safety and Health (NIOSH) reveals that the locations workers take relative to the CMM are usually influenced by visibility requirements and safety concerns [4]. The Mine Safety and Health Administration (MSHA) estimates that at least 28 fatalities involving CMMs since October of 1984 may have been prevented with proximity detection technology [5]. MSHA further estimates that proximity detection could prevent 20% of all deaths throughout the industry [6]."

Jan 1, 2016

By James J. Scott

Three dimensional photoelastic techniques have been developed which provide information on the state of stress at any point in a model investigated. This investigation utilizes these techniques to determine the stress distributions in the pillars and the roof of a room and pillar mine model. Castolite plastic was used for the construction of the model in which a stress pattern was developed by the stress freezing process. Analysis of the stress pattern was accomplished by use of data obtained by observing points in slices from the model with a polariscope and solving data obtained by' the shear-difference method. Slices through the centerline, edge of pillar and centerline of span were investigated. Results of this work provide information on the overall stress distribution on points of stress concentration in compression, shear and tension, show relative magnitude of stress throughout the model and indicate directions of the most important stress values. A generalized roof bolt pattern is developed for room and pillar mines based on the stress distribution. A digital computer was used in the reduction of data and proved to be extremely useful for investigation of this type.

Jan 1, 1963

By E. B. Thorn

The production of portland cement requires that four basic elements -- calcium, silica, alumina and iron -- be ground to a fine powder, homogenized, and fed to the pyroprocessing unit, where it is burned to a cement clinker. The raw material must either be ground wet in a slurry form or dried and ground to a dry powder, with a fineness of approximately 85% passing the 200 M screen. According to the Portland Association's Plant Information Summary, approximately 38% of the U.S. capacity is ground wet and 62% ground dry. The following data is taken from the Portland Cement Association's 1981 Energy Survey: [Million BTU/Ton kW h/Ton Wet Process Plants 5.86 138 Long Dry Process Plants 4.97 123 Dry Preheater Plants 4.03 157 ]

Jan 1, 1984

By Joyce Lappin-Randolph

In 1977, Vertical Crater Retreat (VCR) Mining was developed at the Homestake Mine and by 1983 had become a fully integrated mining method contributing 60% to total underground production. VCR has proven successful for continuous ore blocks exceeding 55,100 tons (50,000 st) with dips greater than 60" and provides a productivity average of 39 tons (35 st) per man shift (tpms) which is 92% greater than Open Cut-and-Fill. Discontinuous ore bodies, small pods, or flat structures not amenable to bulk systems are mined with Mechanized Cut-and-Fill (MCF) and have been able to achieve a 32 tpms (29 st) average productivity. Small, low grade, remnant ore bodies were not economically viable with large scale bulk techniques and couldn't support the development required for a MCF system. As a result, Homestake began researching modified bulk mining methods to increase production rates and maintain safety, while lowering costs. A modified version of VCR with significantly diminished development was prototyped in an effort to reduce initial capital investment and expedite the production phase. This modified method is called Small Block Vertical Crater Retreat (S. B. VCR). Geology The Homestake Gold Mine is located in the northern Black Hills of South Dakota at Lead. Having been active since 1876, it now extends from the surface to the 2,440 m (8000 ft) level underground.

Jan 1, 1987

By Calvin R. Davis

The bucket elevator is probably the oldest known form of conveyor. Its history can be traced back to the days of Babylon where wicker baskets lined with a natural pitch and fastened to ropes operating over wooden sheaves turned by slaves, were used for the elevating of water into irrigation ditches. It is not unnatural for the bucket elevator to be the first in history, for even today engineers and designers recognize that well designed, correctly applied bucket elevators offer unequaled advantages over other bulk material elevating methods. The bucket elevator's vertical design saves valuable floor space. It provides flexibility of machinery layout with lowest initial capital expenditure, which is its principal advantage. While the advantages of the bucket elevator have long been recognized, there has been a tendency to lean away from its use because of high maintenance without reliability. CHAIN Belt Company found that the bucket elevator, if correctly applied, can be built to be as dependable and reliable as any other piece of machinery in today's modern processing plants. It is not difficult to understand why the bucket elevator is looked upon sometimes as a necessary evil in the material handling system. Very little has been published or written about the specific use or application of bucket elevators other than in manufacturers catalogs. Most of today's elevator application was set forth at the turn of the century by Hetzel (1). There have been many improvements made in the manufacturing techniques of elevator components, improvements in material selections, all which can be used to improve today's bucket elevator. To best understand the improvements which have taken place recently in the design and application of bucket elevators, an understanding of basic elevator principles is desirable. In general, it can be said that bucket elevators are classified into two basic types : (1) centrifugal discharge and (2) continuous. Elevators in use today are either of the centrifugal discharge type or the continuous type, or a combination of both in special applications.

Jan 1, 1958

By Daniel G. DiCanio

Investigation of the costs of industrial accidents dates back to the 1920s. The Bureau of Mines was one of the pioneers in accident cost investigation with numerous studies published between 1928 and 1933. The bulk of these early investigations dealt only with costs which appeared as payouts on company books; that is, the direct cost of insurance premiums and the costs of medical expenses which resulted from industrial accidents. These early investigations, especially the Bureau's study of accident costs in Pennsylvania and Indiana coal mines provided the first real evidence that promotion of industrial safety pays back in dollars as well as in human life and wellbeing. In the 30s and 40s, investigations began to accumulate evidence that industrial accidents impacted more than just the direct operating expenses of a company (i.e., higher insurance premiums). The work of Heinrich pioneered these investigations, and produced strong evidence that the un¬insured costs of accidents far outweighed those costs covered by insurance. Heinrich developed and published a ratio of insured to uninsured costs of 1.4. Despite his cautionary statements about blanket application of this ratio it is used even today to estimate total costs of accidents. Simonds, in the late 40s and early 50s, extended the definitions of uninsured or indirect accident costs and developed what is now regarded as the principal method for estimating the total economic impact of industrial accidents. Simonds' method served as the basis for development of the logic of the Accident Cost Indicator Model (ACIM). However, several departures from Simonds' method were made to satisfy certain requirements imposed by the Bureau of Mines, and because information gathered during the course of our investigation justified a departure. These departures are noted in the discussion which follows.

Jan 1, 1977

By Maurício Covcevich Bagatini, Maycon Athayde

Nowadays, the HPGR (high-pressure grinding rolls) is an intermediate step between filtering and balling in the most modern iron ore pelletizing operation. The operation debottlenecks filtering process and reduces pressure over the typical milling process to control particle size to the balling. The present study evaluated aspects of microwave application to the iron ore concentrate fed to HPGR in a bench scale unit. Iron ore concentrate was irradiated varying the microwave exposure time and grinding efficiency was evaluated. The moisture influence in the HPGR efficiency was also assessed. The pellet feed blaine surface area (BSA) improved by 300 cm2/g and % < 325# fraction by 3%. Scanning electron microscope (SEM) images show the formation of micro-cracks onto the particle surface induced by microwave; the effect observed helped improve the milling process performance, in addition to the moisture reduction observed due to the temperature increase.

By M. J. Ross, D. A. Norrgran, J. A. Wernham, J. N. Orlich

INTRODUCTION Laboratory testing for magnetic concentration circuit design is a requirement, just as it is for most other types of concentration. Natural variations in raw materials allow on1 y the broadest of generalities to be made regarding magnetic separation. Further, magnetic fields are geometry dependent, leaving fundamental models of a separator overly dependent upon the exact conditions for which the models were derived. Despite this, an understanding of the basics of magnetic separation and of the problem to be attacked can result in rapid progress towards the final circuit design with a relatively simple testing program. Magnetic Separation Basic Principles A magnetic field can readily be understood in terms of lines of flux. A familiar demonstration of these lines of flux is the pattern of iron filings on a sheet of paper when a magnet is placed underneath. Lines of flux2 are measured in Gauss (1 line/cm2) or Tesla (10000 gauss). Regions of high field strength have a greater number of lines. Field direction is indicated by a convergence of lines. When a particle is placed in a magnetic field it cuts the lines of flux and alters them in one of three basic patterns. These patterns are referred to as diamagnetic, paramagnetic and ferromagnetic. Diamagnetic materials have electronic structures which react to oppose an applied magnetic field. This opposition acts to locally reduce the applied field slightly. The visualization is that lines of flux diverge and go around the particle. Because of this divergence or opposition, a diamagnetic particle will tend to move towards regions of lower flux density. That is to say that the particle will be repelled by a magnetic field. Aluminum oxide and napthalene are examples of diamagnetic materials. Paramagnetic materials have an electronic structure which increases an applied magnetic field. Although these materials also exhibit diamagnetism, they have randomly oriented impaired electrons which align with the magnetic field. The resultant local field enhancement is significantly larger than the diamagnetic opposition. The visual-

Jan 1, 1986

By Francois J. E. Scholtz, Raymond J. Davidson, Peter Greenhalgh, R. Paul Riley

A 1 t/d continuous elution pilot plan is being operated by General Mining at their Grootvlei Gold Mine using the technology developed at the Anglo American Research Laboratories. Flowsheet design and plant erection was carried out by Van Eck & Lurie and completed in December 1989. Following the conclusion of six test runs designed to optimise reagent additions, it was shown that elution efficiencies of 98-99% could be achieved using reagent additions as· low as 16 kg/ton of carbon NaCN and 28 kg/ton NaOH while consistently producing eluted carbon containing less than 50 g/t gold. Significant savings were indicated when compared and power were indicated when com­pared with the traditional batch AARL, Zadra and Micron alcohol elution procedures.

Jan 1, 1990

By Sepp A. Kutschera

are gaining increased interest for over­burden removal and ore production at large open cast mines. The application of bucket wheel excavators is still tied to soft un­consolidated rocks and soils, while belt conveyors can cope with all kind of matri­als restricted only by the top grain _ size. Therefore, mode of transport and the re­quirement of down stream ore processing de­fine the materials size distribution. These requirements are usually met by primary crushing or scalping. The paper discusses general applica­ tion criteria of bucket wheel excavator with systems primary for in-pit overburden crusher removal. and It _indeapits scalper units and discusses their technical and operational features. It further com­pares the capital and operating cost struc­ture relative to the syste

Jan 1, 1992

By Timothy P. Smirnoff, Anthony Stirbys, Amanda Elioff

The construction of the continuing expansion of the Los Angeles Metro System has required the construction of eight new station structures. One contractor proposed, as a construction alternative for the support of excavation of the Hollywood/Vine Station, the use of soil-mix walls instead of the conventional soldier piles and wood lagging. Soldier piles and shotcrete or wood lagging support systems had been generally used on the other sub-way station excavations constructed to date throughout the system. Immediately east of that station and in almost exactly the same geology, the Hollywood/Western Station was being excavated at the same time using a conventional support system. This paper com-pares the performance of these two support systems in the alluvial soils of the Los Angeles Basin.

Jan 1, 1997

By Liaqat Ali Shah, Muhammad Farooq, Zait Ullah Shah, Francisco Rolando Valenzuela-Díaz

Bentonite collected from Nowshera (Pakistan) was treated with NaCl, and the < 2-μm clay fractions were separated by sedimentation process. The textural changes in NaCl treated purified bentonite were compared with raw and physically purified sample. It was detected that the NaCl-treated purified bentonite and the sample purified by simple sedimentation, respectively, consist of sodium-montmorillonite and calcium-montmorillonite as a major clay mineral. The honeycombed-type morphology was observed for both the purified samples; however, the particles of NaCl treated purified bentonite were relatively in a compact form. The particle sizes of both the purified samples were found considerably smaller. The high volume percent of the fine particles was noticed in the NaCl-treated purified bentonite. This attributed that the sodium exchange has a valuable impact on the bentonite dispersion in aqueous media during particle size measurement. The relatively high mesopore area/volume and micropore area/volume and specific surface area (SSA) were detected in purified samples. The NaCl-treated purified sample showed relatively high mesopores area/volume than the sample obtained by simple sedimentation. These changes seem to be originated from either high montmorillonite contents and/or the smaller particle size, which might be produced after the layer rearrangement during the interlayer cation replacement by Na+ ions. The large SSA and high porosity of purified samples particularly the NaCl-treated bentonite suggest their potential use as adsorbents, catalysts, pharmaceuticals, and cosmetics.

Jan 7, 2021

By Egons R. Podnieks, Wallace W. Roepke

Mining technology to utilize vital lunar resources will be required for any commitment to permanent lunar basing. Lunar mining must be viewed both as a major supporting element for space resource commercialization and for creation of human settlements on lunar and planetary surfaces to support long-range space exploration. The Apollo missions to the lunar surface and results from fundamental research on analogue lunar rocks by the Bureau of Mines, and others, have provided the initial data for developing lunar mining technology. The multi-disciplinary research projected in this paper outlines the scientific and engineering needs to realize the lunar mining goals.

Jan 1, 1990

By X. Xie

The dissolution behavior of palladium powder in thiourea solutions has been studied. The variables studied included temperature, stirring speed, and concentrations of thiourea, acid and ferric ion. Palladium was found to be soluble in thiourea solutions in the presence of an oxidant such as ferric ion. The dissolution of palladium in thiourea solutions was found to be chemical reaction controlled with an apparent activation energy of about 2S.3 kJ/mol.

Jan 1, 1995

By J. Ye

A comprehensive flotation study has been carried out on a Chinese fluorspar ore using the packed flotation column developed at Michigan Technological University. The results are compared with that of a conventional mechanical flotation method on the same feedstocks. Key factors controlling flotation performance of both methods are evaluated based upon a simple statistic design. The flotation concentrate produced in one stage of the packed column has 4-S% higher recovery and much lower silica impurity content than that produced by up to six stages when a conventional mechanical cell is used. The results also show that the packed column flotation process is particularly suitable for recovery of finer fluorspar particles.

Jan 1, 1992

By D. E. Larson

The U.S. Bureau of Mines has developed a image analysis methodology to correlate the energy consumed during the grinding of an ore to the mineral liberation achieved. Energy consumption values are obtained using a laboratory-scale ball mill equipped with a torque sensor, and an automated image analyzer is used to determine the liberation present in ground products. By combining liberation information with energy consumption data an appraisal can be made of the energy required to liberate the mineral(s) of interest. Results of tests performed on a complex sulfide material determined the effects of grind duration on the liberation achieved and the energy efficiency.

Jan 1, 1995

By N. A. Abdel-Khalek

The objective of this investigation was to compare the results of counter-current flotation column versus conventional flotation cell for the cleaning of a sulphur ore and its discrete size fractions. The tests were carried out using diesel oil as a collector and alcohol as a frother. Generally, flotation column produced concentrates of higher grade. For example, the grade of a rougher concentrate for a given feed obtained with the column increased by 33% higher than that produced with the flotation cell. Such higher grade could not be obtained using conventional cell even after 3 cleaning stages. Moreover, the column gave superior results for flotation of fine and ultrafine particles.

Jan 1, 1991