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By John C. Balla

The Troy deposit is located in northwestern Montana, approximately 17 mi south of Troy. The deposit is a stratiform, strata- bound, copper-silver deposit which occurs in the Revett formation of the Proterozoic Belt Supergroup. The Revett formation is approximately 1730 ft thick in the vicinity of the Troy deposit, and is divisible into three units. The upper Revett, approximately 250 ft thick, is the host for the orebody. The Revett represents a deltaic environment. The Troy deposit was discovered by Bear Creek Mining Company in 1 963 during the course of a reconnaissance stream sediment sampling program that was designed to discover strata-bound copper deposits. The deposit is approximately 7500 ft long, 1800 ft wide, and averages 60 ft thick. It is bounded on the north by outcrop, on the east by a post-mineral fault, on the south by diminishing grade and post-mineral faults, and on the west by diminishing grade. Ore reserves are 64 million tons with a grade of 0.76% Cu and 1.58 oz Ag per ton. The mine is presently operating at a production rate of 4.2 million oz of silver and 20,000 tons of copper per year.

Jan 1, 2013

By Weston Bourret

The need for wartime supplies of uranium for the Manhattan Project prompted a 1944 study of uranium in South Africa. Uraninite had been reported by R.A. Cooper in 1923 in a Witwatersrand heavy- mineral concentrate, and the search for uranium, therefore, included the district's 30 operating mills. The method of investigation was simple: take bulk concentrate samples from the Wifley tables and determine their mineralogy. Samples were taken on a daily basis, although weekly composites also were taken of some mills. In 1944, most mills had simple gravity circuits and produced (I) a gravity concentrate, and (2) an all-slime [-75 pm (-200 mesh)] product. The tonnage throughput was known, and from that, head assays could be calculated. Concentrate samples were sent to the United States for chemical analyses. A Geiger counter set up in a Johannesburg hotel room provided preliminary data. The early data showed uraninite to be widespread. Microscopic, mineragraphic, and siezing tests were all under- taken in Johannesburg. Ultimately, tests led to a high grade (+90%) uraninite concentrate. Platinum and other heavies were the impurities. In seven months, the investigations had reached the stage where it was possible to forecast an annual production of 5.4 to 7.3 kt (6,000 to 8,000 st) of U3O8. The estimate is still realistic. Additional details are found in Bourret (1981).

Jan 1, 1991

By R. Dewey

WHAT IS AI? It's very hard to say. Most researchers and practitioners disagree with nearly any attempted definition, but most would agree that A1 does deal with the development of computer-related methods o f problem-solving. Artificial intelligence is a discipline which seeks to emulate human anatomy and/or thought processes by applying computer science, electronics, and mechanical engineering to the development of natural language processing, machine vision, robotics, and knowledge-based expert systems. Integration of these four fields will someday produce the robots of today's science fiction. A1 addresses problems of structuring large amounts of knowledge and representing relationships with rules and semantic frameworks rather than with mathematical equations. A1 is convergent rather than divergent - - conventional conputer applications use relatively small quantities of input to generate large output, but A1 generally reduces large amounts of information to establish a few major conclusions. The development of A1 has prompted greatly increased efforts on the part of scientists and engineers to understand just how humans think, organize information, approach problem-solving, and form conclusions. Some of the more exciting and possibly far-reaching advances in A1 are coming in this more-or-less soft-science area. Thirty years of A1 research (dating from a 1956 conference at Dartmouth College at which the term A1 was coined) has already spawned many widespread, almost ordinary, products: window graphics, hand-held controllers (mouse). function menus, etc., all in an attempt to make computers and people more compatible. WHAT IS AN ES? A1 can be used to develop EXPERT SYSTEMS, which are computer programs or systems which contain knowledge and rules by which problems can be solved. or at least by which possible solutions can be suggested for very complex problems. A1 can be used to better define problems so that solutions can be found. An ES is designed not to process numbers, but to process information according to rules and logic derived from actual practice and experience. WHY AI? WHY ES? Companies are increasingly aware of the value of accumulated knowledge and experience in designing, building, operating, and maintaining the increasingly complex or expensive physical plants in any business. As knowledge branches out and becomes more specialized, the accumulated learning of a veteran operator or manager or engineer becomes a scarce resource well worth preserving. EXPERT SYSTEMS offer a means of doing that, reinforcing, not replacing, human capabilities.

Jan 1, 1987

By Annan Cook

Cyprus Metals' Sierrita mine is located in the Pima Mining District, Pima County, Arizona (Fig. 1), which is one of the largest known porphyry copper districts. The ore body is part of a large mineralized system that includes Cyprus' adjoining Esperanza mine. The copper and molybdenum grades being mined at Sierrita make it one of the two lowest grade porphyry copper mines in the world Mineral production from the district was first recorded in 1876. Copper from replacement deposits in carbonate rocks and copper¬-lead-zinc from veins in volcanic rocks were mined from several deposits. However, it was not until 1957 that the district commenced to become a major copper producer with the beginning of production from the Pima mine, which was the first open pit operation. Since that time, seven other open pit mines have come into production. Because of the variable copper prices and high operating costs, not all of the mines are operating today. A map of certain outcrops, plutons, and open pits, as well as older underground mining operations, in the Pima district is shown in Fig. 2.

Jan 1, 1991

By A. A. Peshkov, N. A. Matsko, K. N. Trubetskoy

It is possible to divide the general objectives of a company into two components: maximum expected profits and viability over time. These components are designed to maximize the companies value over time. The evaluation of a project includes both a discounted cash flow (DCF) analysis and a risk analysis. The DCF analysis determines whether the project should be accepted or rejected, and the risk analysis helps to forecast possible deviations from the original estimates. However, the results of both methods do not allow for a quantitative comparison between the main objectives of the venture, and they do not resolve the issue of whether it is advisable to sacrifice immediate profits for future profits. This paper attempts to resolve this issue. The present research was carried out on mining projects with different waste-extraction schedules. Calculations were made using the US Bureau of Mines' usage-of-costs model. Russian experience in open-pit mining is reflected in this paper.

Jan 1, 1996

By G. J. Hartman

The Fort Cady in situ borate mining project involves recovery of boron from a mineral deposit located over 1400 feet below the surface. The resource recovery method is being developed using in situ mining technology employing weak acid solution injected directly into the ore body. As the acid contacts the calcium based ore (primarily natural colemanite), the contained borate values are digested as boric acid. This boric acid solution is then pumped to the surface by use of submersible pumps. At the surface the borate values are recovered as a finely divided solid white powder after a series of chemical reactions and precipitations resulting in the production of calcium borate. The refined product is then sold under the trade name CADYCAL 100.TM All environmental permits for up to a production rate of 90,000 tons per year have now been obtained. These permits required an Environmental Impact Study (EIS) for federal lands and an Environmental Impact Report (EIR) for the private portion of the property. Regulatory permitting took over 5 years to obtain all authorizations for this operation. The ore body has an average thickness of 118 feet extending over 273 acres. At a production rate of 90,000 tons per year with only a 70 percent resource recovery allowance, in place reserves are sufficient to sustain production for over one hundred years.

Jan 1, 1997

By G. Bierie

The conveying of bulk materials is prone to problems. These problems can reduce the capacity and efficiency of the plant, and even threaten the health and safety of the workforce. This presentation will look at new conveyor technologies systems, and how, used separately or in combination, they can improve material handling.

Jan 1, 2007

By J. Keng, S. T. Chen, T. M. Shih

Kwanyin Tunnel is presently the longest (7.7 km) railway tunnel in Taiwan. Due to heavy railway traffic, a pass-by station will be built inside the tunnel to increase the traffic flow. Since the concentration of toxic gases released by the locomotives may reach dangerous levels, a research program was conducted for the purpose of designing a ventilation system which could dilute and/or remove the toxic gases to maintain an acceptable pollutant level. The program consisted of two parts. The first part was field measurement during which the concentrations of pollutants and wind velocities were measured at various points inside the tunnel to acquire basic data regarding ambient air quality, piston effects for the different types of trains, and existing ventilation conditions. Weather data (temperature, humidity, atmospheric pressure, wind direction and velocity) were gathered at many stations, both on the surface and inside the tunnel. The amount of pollutants released by each type of locomotive for various conditions were also measured. The second part of this study involved establishing mathematical models for predicting the air quality of the various proposed ventilation systems. Three different models were used for this work. The first one is a piston effect model which assumes that the gases and air undergo immediate mixing inside the tunnel. The second one is also a piston effect model which assumes that the diffusion ability of the gases is zero. The third one is a conventional ventilation model which was used for natural and mechanical ventilation conditions. From the result of field measurement and mathematical model studies, a ventilation system was chosen with consideration of both ventilation effects and construction costs.

Jan 1, 1987

By P. K. Davis

The results of a previous basic study of the flow and design characteristics of the hydrocyclone has shown that a recovery as high as 99% with a product rating of 0.95 can be achieved on a "batch?2 basis with a single, water-only cyclone if it is configured properly. The next logical step was to demonstrate continuous processing of gob for the efficient recovery of coal by means of a laboratory-size demonstration system. A project to design and construct such a single-cyclone system was also sponsored by the U.S. Department of Energy. A recovery of 93% with a product rating of 0.89 was demonstrated. The system design and the data taken are discussed.

Jan 1, 1989

By T. R. Ellis

Considerable movement is afoot internationally to rationalize standards and regulations relating to valuations and the qualifications for valuation professionals. In July 2000 the International Valuation Standards Committee released expanded standards, and additional important improvements are planned by 2003. Possible updates to the International Accounting Standards (IAS) and potential adoption of IAS by the U.S. could significantly impact minerals appraisers. Standards designed specifically for mineral asset valuation are under development in Canada and the U.S., with Australia’s internationally respected VALMIN Code providing the benchmark. In the U.S., the all-encompassing Uniform Standards of Professional Appraisal Practice (USPAP) is annually modified and continues to gain deeper acceptance, while the SEC holds fast to its antiquated rule prohibiting reporting of a quantitative estimate and value for non-reserve mineralization. Some important international trade agreements are driving actions to free the trade in professional services. In July 2000, an international workshop was held to initiate discussion on minimum qualifications for appraisers to work internationally. Pressure for uniform minimum qualifications and rules for professionals internationally will continue to build. The U.S. is historically among the slowest countries to implement such initiatives, with its state level licensure barriers having the potential to cause some of its professionals to be stranded in an international backwater. Structural change is needed in Australia’s VALMIN Code to remove conflict with the latest International Valuation Standards. The mineral valuation standards developers of Australia, Canada and the U.S. should work jointly on updating VALMIN for global use.

Jan 1, 2001

By J. A. Dille, J. P. Hand, J. D. Brown

The purpose of this paper is to inform members of the coal producing and consuming community about techniques used by The Carter Mining Co. to control product quality at a large surface coal mining operation. During the early years of mining operations, coal quality received adequate attention but the company's main emphasis was to build up its production rate and minimize mining costs. While these goals are still of prime importance, coal quality has received additional attention in recent years. An objective that no coal shipment should exceed any contract or company-imposed coal quality specification has been successfully met. To implement this guideline, geology and coal quality modeling procedures were improved, in-pit drilling and blending programs were refined, and detailed shipment procedures were developed.

Jan 1, 1987

By S. K. Kawatra

With the increasing importance being placed upon modernizing the coal industry as a result of recent developments in the international energy balance, computer control has been and is being instituted in many coal cleaning plants. Control techniques that are well established in many base metal industries have been adapted to coal washing. Essential to any control scheme is an accurate measure of the parameter which is to be controlled. A sensor is required that will provide information both quickly and precisely. In fine coal circuits, the critical parameter that must be measured and controlled is the per- cent ash contained in the clean coal product and tailings. Measuring the ash content of these slurry lines on a continuous basis enables the operating conditions in the circuit to be adjusted so as to obtain optimum separation efficiencies at all times. An on-line ash monitor has been developed and tested at Michigan Technological University which is capable of making percent ash and percent solids determinations instantaneously. Two radioisotopes are employed in this system to generate signals that can be related to the density and the ash content of the slurry. Such data provide a means to execute a short term control strategy.

Jan 1, 1982

By P. James, L. J. Steiner, F. Turin

NIOSH researchers and an industry partner conducted an investigation to study the effectiveness of ergonomic interventions in mining. The study required a significant commitment of time and resources from the cooperating site, Bridger Coal Company. This paper focuses on some of the challenges faced by the researchers and their cooperator. Challenges included the need to redesign methods of identifying and prioritizing injuries, and the need to train the workforce in ergonomics while still maintaining progress and interest in the process. The authors discuss some practical interventions implemented by Bridger Coal to date, and discuss future research implications brought about by PacifiCorp’s Generation Business Unit, who monitored the project to determine whether an employee-owned ergonomic process could be implemented throughout their operations.

Jan 1, 2003

By Waclaw Dziurzynski, Janusz Tracz, Danny Wooton, Andrzej M. Wala

The purpose of this paper is to present validation studies of the mine-fire simulator using data gathered from an actual mine fire which occurred in November 1991 at the Pattiki Mine. This study evaluates the suitability of the computer software package for modeling underground fires. The paper also discusses the importance of the on-line monitoring system for the validation process.

Jan 1, 1995

By C. E. Brechtel

Bench cut-and-fill stopes with heights between 85 and 105 ft are being excavated in the lower levels of the B-NEATH Zone. Estimates of pillar strength and pillar loading indicated a high probability of pillar failure. Some changes in mining practice were made to minimize impacts of pillar failure and a rock mechanics instrumentation program was employed to monitor stability during mining of the first stopes. Limited pillar failure, in the form of destressing, was observed in the initial stopes; however, global stability during mining was good. Instrumentation data indicated that predictions of pillar strength and stress were quite close to field results.

Jan 1, 1989

By C. M. McCulloch

More and more mining underground is being conducted using the longwall method. Likewise, many new surface mines use area or mountaintop removal methods. These methods can have a significant impact on surface and groundwater resources. The overall study of the effects on surface and groundwater from mining is referred to as the probable hydrologic consequences (PHC) determination of mining and reclamation. Collection and interpretation of information concerning groundwater and surface water quality and quantity, as well as detailed geologic analysis, is required to adequately define the impacts of mining. This paper discusses the present day requirements and methodology of preparing a PHC for a large mining operation in the eastern coalfields.

Jan 1, 1995

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

Overcasts are indispensible ventilation control devices to permit one airway to pass over another without mixing in room and pillar coal mining. The airflow distribution inside the overcast depends on its spe-cific configuration at which the flow enters into it. This study uses 3D numerical simulation to examine the pressure and velocity distributions inside an overcast. The effects of the overcast angle on the flow field are also examined. The flow is assumed to be turbulent and isothermal and the standard k-e model is utilized. Simulated results display flow separation and recirculation regions of different sizes occurring not only upstream and downstream from the overcast but also inside it. The results also show that the size of the recirculation regions in-creased with the increase in the angle before and after the overcast influencing significantly the flow field and pressure losses. The stream-lines are plotted to show the 3D structure of the flow field. The results from the simulation can guide overcast design commonly used in un-derground coal mines. Keywords: 3-D simulation, Overcast, Room and Pillar, Turbulence, Recirculation Region

Feb 27, 2013

By James A. Curry

Table I identifies the maximum cost of the individual provisions with spoil disposal in Appalachia leading at $3.98 per ton, This was followed by deep mine subsidence control and monitoring at $1.66 per ton. At the request of the U.S. Department of Energy, the Bowser-Morner Testing Laboratories of Dayton, Ohio, evaluated Consol's cost estimates for 14 of the 21 regulatory provisions the company studied. It is interesting to note that Bowser-Morner concluded that Consol's estimates of costs were very conservative and that the actual costs will be substantially higher than what the company reported. In 1978 a joint committee of the National Coal Association and the American Mining Congress made estimates of cost impacts under 11 OSM permanent rules (see Table II). Six rules applied to mid-western strip mining were projected to cost $6.52 to $17.17 per ton. Five rules applied to mid-western strip mines showed costs ranging from $.91 to $6.11 per ton. Three rules applied to deep mines (regardless of region) were seen raising costs from $ .57 to $2.67 per ton. The joint committee reported trouble developing overall figures because member firms used widely different assumptions in calculating their costs. That same statement could no doubt be made when comparing most cost data available today.

Jan 1, 1980

By James M. Prudden, Jon C. Sprague

Valdez Creek Mining Co. properties consist of multiple intersecting paleo-placer channels containing appreciable quantities of coarse gold. Reverse circulation drilling, combined with geophysics, is used for both exploration and development reserve determination. Classical drill-blast-load-haul open pit mining techniques used for the 22,000 cubic yard per day production schedule required modification to compensate for arctic winter operating conditions. High wall stability problems within the glacial sediment overburden necessitated developing multiple dewatering methods and variable pit slope designs to eliminate unstable pit wall conditions. Processing mine run fluvial gravels utilized a classical winter protected screening plant-sluice box recovery system enjoying high metallurgical recoveries and zero discharge tailings disposal.

Jan 1, 1987