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Computer applications in mine 'production' planning and control are concerned with the here and now. In production planning and control we are dealing with tactics as opposed to strategy. Our objective is to make the best of the situation in the short term, i.e., in a relatively fixed environment with relatively fixed plant, equipment, and labor. Environmental factors include not only the geology of the deposit but also market factors (such as price) and governmental constraints and regulations. Mine production planning systems are applied at the interface between concept and execution. Mine production control systems are applied at the interface between execution and revised operating practices or a revised concept. Fig. 1 shows the information flow that takes place regardless of whether the planning and control systems are manual or automatic. The feedback that results depends on the feedback mechanism that has been established, and this feedback can be enhanced by careful systems analysis and design. Chronologically, production planning and control activities support the last in the series of line functions that are ordinarily performed by mining companies. The first of these is exploration, the second is evaluation and development, and the third and final function is production.

Jan 1, 1979

By T. M. Ruff, W. G. McCoy, M. J. Beus, S. Iverson

Monitoring conveyance position and wire rope load directly from the skip or cage top offers several significant safety and production advantages. The Spokane Research Laboratory of the National Institute for Occupational Safety and Health (NIOSH) developed a shaft conveyance monitoring system (SCMS). This system consists of position and guide-displacement sensors, a maintenance-free battery power supply and a new sensor, which is mounted on the wire rope with a Crosby Clip, to measure hoist-rope tension. A radio data link transmits sensor output to the hoistroom. A state-of-the-art automated hoisting test facility was also constructed to test the concept in a controlled laboratory setting. Field tests in full-size shafts are now underway.

Jan 1, 2000

The visible portion of accounting-record keeping and preparation of financial statements-suggests a lack of sophistication and imagination. In reality, accounting is based on a large body of theory. Accountants philosophize, theorize, judge, create, and deliberate as a significant part of their professional practice. The subjective aspects that are so critical to current accounting practice, such as searching for truth and fact, judging what is fair presentation, and considering the behavior induced by presentations, are often overshadowed by the appearance of exactitude, precision, and objectivity that accompanies the use of numbers to express the financial results of the enterprise. * Fundamental accounting principles are hypothesized in the same manner as mathematical principles. These principles are justified by acceptability and intuition. Accounting theory is built upon these hypotheses, resulting in a coherent set of standards and rules. Although it does not specifically address every situation that may be encountered, this conceptual frame- work enables the manager or analyst to resolve specific situations. This framework also aids in the understanding and confidence in financial statements and ensures comparability between statements from different companies. This framework is referred to as "generally accepted accounting principles," or GAAP.

Jan 1, 1999

By G. T. Adel

Hindered-bed separators are often used in the minerals processing industry to classify particles according to size and density. A new technology, known as the Eriez CrossFlow, was recently developed to overcome some of the limitations associated with hydraulic separators. The innovative feature of this unit is a novel feed presentation system that improves separation efficiency and capacity. In the present work, a detailed process engineering evaluation was conducted to determine the basis for the improved performance of this unit. The evaluation included controlled separation tests using well-characterized feeds, particle and liquid tracer experiments and mathematical modeling studies. Data obtained from this work show that the new separator is capable of maintaining good separation efficiencies at higher solid feed rates than traditional designs due to improved hydrodynamics in the separation zone. This paper reviews the operating principle of the Eriez CrossFlow separator, discusses the results of the tracer experiments and modeling studies and presents test data obtained from recent laboratory and plant trials. Key words: Size classification, CrossFlow separator, Hindered-bed separator, Hydraulic separator

Jan 1, 2003

By Ross W. Smith, Salim Akhtar

Flotation of oxide minerals, particularly silicates, with cationic collectors differs substantially from classic flotation of sulfide minerals using sulfhydryl collectors. In the case of cationic flotation of these minerals, in general: 1. There is a greater importance of electrostatic interaction between mineral and collector. 2. Longer-chained collectors are required; as a rule at least 10 carbons must be present in the hydrocarbon chain. 3. Moderate concentration of collector is required. 4. Attachment between collector and mineral appears to be less strong even though the system may exhibit a large contact angle. 5. Required conditioning time before flotation is usually relatively short. 6. There is sensitivity to slimes. 7. The collectors usually possess frothing power. 8. Selectivity of cationic collectors for specific minerals is usually poor. Almost any of the oxide and silicate minerals may be floated using cationic collectors. However, specific response to these collect- ors varies with mineral type. The following classes and minerals are

Jan 1, 1976

In the hierarchy of performing mine planning tasks, production scheduling is naturally at the bottom. Yet good production scheduling is probably the most demanding and difficult task to achieve for various reasons. Being the last task in the mine planning hierarchy, a proper production schedule must not only conform to both the long-range and the short- range mine plans but also satisfy many practical details that are unique to day-to-day operations. For example, the averages which were good enough for both long-range and short- range mine planning are no longer good enough for production scheduling. Instead, the variations become the overriding concern. The answer must also be obtained quickly and on time, thus adding another dimension to the overall problem. Because of these considerations, many production scheduling problems have been begging for solution during the past decade. Many attempts were made to solve the production scheduling problems in the past using computers and the available operations research (OR) techniques, particularly among academic groups. However, it is probably true that, compared with the current full-time computer usage in long-range and short-range mine planning, very little computer usage is being made in production scheduling to date.

Jan 1, 1979

By John P. Dunford, Lewis A. Martin

Researchers from the Spokane Research Laboratory, National Institute for Occupational Safety and Health, in cooperation with engineers from the Department of Mining and Geological Engineering, Montana Tech, Butte, MT, conducted tests to evaluate the tensile strength, fiber count, and adhesion of shotcrete applied to panels at the Chief Joseph Mine, a research and training facility operated by Montana Tech. The tests were conducted in the mine ramp 45 m (150 ft) inward from the access portal at a 15.25-m- (50-ft) long test area divided into five 3-m- (10-ft) long sections. The shotcrete was applied with an Aliva 240.5 machine fitted with a predampener. Different amounts of fiber were entrained for each panel. Background data for the tests were obtained from earlier tests in Nevada, where the typical amount of fiber in the shotcrete is 6.54 kg/m3 (11 lb/yd3). All shotcrete was applied to a minimum thickness of 76 mm (3 in). Cylindrical cores were drilled at the wall-rock interface, and adhesion was tested after 28 days of curing. The goal of this research is to reduce the need to install multiple supports at the advancing face by creating a safer mining system that limits the time miners are exposed to unprotected roof.

Jan 1, 2005

By J. Scott McDougall, J. Herman P. Eng. Vanderlaag

An underground mine fire can seriously threaten the lives of all personnel in the mine. This fact makes fire emergency planning a high priority in the mining industry. The optimum warning alarm must be fast and able to reach all miners, regardless of their location or work activity. Current means of fire warning are varied, and include such methods as stench, telephones, and word-of-mouth (messengers). Unfortunately, none of these methods are entirely satisfactory. A novel fire warning alarm which enables instantaneous warning of all underground personnel, the Canary Nine Messenger System, has been developed by VLF Magnetic Systems Inc. in conjunction with Noranda Technology Centre and the U.S. Department of the Interior - Bureau of Nines. The warning is sent by an electromagnetic signal which penetrates through mine rock to receivers housed in the battery packs which also power each miner's cap lamp. A loud buzzer in the integrated battery/receiver unit and the flashing of the cap lamp alerts miners to incoming messages. Testing of prototype equipment has demonstrated that the transmitted signal is capable of penetrating through over a mile of mine rock and activating the receiver. This report describes the theoretical basis for through-the-rock ultra-low frequency electromagnetic transmission, and the design of recently available transmitter and receivers.

Jan 1, 1995

By Richard Hogg, Erol Kaya, Jan M. Mutmansky

Characterization of the size, shape, chemical composition, and mineralogical content of mine airborne dusts generally requires a larger mass of dust particles than is typically collected using traditional sampling devices. In this paper, the general design of a passive dust collector is described and the field results are presented. The collector was constructed of galvanized sheet metal duct with a resin-coated honeycomb to provide an elutriation-type system for particle collection. Several versions of the collector were used in the field portions of the research. The dust samples collected from underground coal mines were found to possess angular particle shapes, relatively consistent size distributions, and elemental compositions that showed relatively little variation, at least for the more prevalent elements. In addition, the distributions of particles sizes obtained from the passive dust collector appear to be similar to those of samples collected at the same time in a conventional personal sampler except that the passive device seems to collect a larger quantity of coarse, non- respirable particles. Conclusions on the suitability of this dust collector for collecting characterization samples are presented. In addition, the potential for using such a dust collection system for supplying dusts for biomedical research is discussed.

Jan 1, 1993

By A. Aubut, A. Proulx, O. Tavchandjian

Results obtained from conditional simulations and multiple indicator kriging were compared in the assessment of two different mining methods proposed for the extraction of the down-dip extension of a nickel-sulfide ore body located in the Thompson mining camp, Canada. An enhanced turning band simulation algorithm, supplemented with an unfolding technique, was used. A floating stope optimization process was used to effectively compare tonnage and grade figures. A calibration exercise was also conducted in the upper portion of the ore body. This study demonstrates that conditional simulations provide better spatial models for conceptual mine design and capital budgeting decisions.

Jan 1, 2004

This paper discusses how the link between design software tools and recycling models can be established in order to predict the recyclability of the car during the design phase, as well as to be able to apply design for recycling on a solid technological basis. Due to the complexity of the design of the car, optimisation of recycling can only be realised based on a sound technological basis, in which the dynamic and statistically distributed parameters affecting the recycling rate are described and understood. This paper gives a brief overview of the dynamic and recycling models, which are developed for optimisation of the recycling of the car and the calculation of recycling rates of the car in the design phase in view of EU legislation. Moreover the possibilities for modelling of shredding and liberation within the recycling system are discussed. The performance of experiments on a fundamental basis in order to collect statistically correct industrial data, supported by a closing mass balance, is referred to on the basis of a large scale industrial recycling experiment. It will be shown how design for recycling and environment can be supported by the sophisticated models as developed by the authors.

Jan 1, 2005

By I. S. Parrish, D. W. Kappes, G. G. Austin

Micron-sized gold disseminated in lower Cambrian siltstone has been found at the Sterling mine near Beatty, NV. A shoestring-shaped body has been developed by central and fringe drifts and is being mined via a modified retreat room and pillar system. The siliceous ore crushed to 5.08 cm (2 in ) is stacked to 4.6 m (15 ft) over a layered sand, gravel, and impervious PVC base. Gold is leached using a 0.1% cyanide solution and deposited on activated coconut shell carbon. Stripping of the carbon by hot solutions of 1% NaOH and 20% Ethanol yields overall recovery of about 75% of the fire assay head.

Jan 1, 1983

By Guiseppe Bonifazi

This work applies the definition of "separation function" already introduced in the paper presented at the XVIII IMPC. This 'function" (defined for a certain size distribution after comminution of an ore) refers to the recovery distribution of a mineralogical species in a product made up of all the particles having at least a given content of that species. Many tests would be required to determine the liberation function for each mineralogical species, particularly for complex ores. Several stages of comminution would need to be examined and the mineralogical composition of the particles of each grain size class would need to be analyzed for each process step. A quick and dirty method is shown for obtaining the "separation function". It is based on the processing of data from topological maps of polished and/or thin representative sections of ore. By superimposing grids of different sizes over these maps and with appropriate combinations of mesh sizes, it is possible to simulate the grain size distributions linked to different stages of comminution and then evaluate the mineralogical composition of each grain. The procedure is carried out full automatically and can simulate a complete treatment circuit, imposing cut-off grades for the products at each separation phase. It is also possible to predict the results of treatment processes that involve grinding phases. The procedure has been successfully applied to complex ores containing several useful components.

Jan 1, 1995

By S. Bassignani, D. Ippolito

In Italy at the moment there is a program which involves for the future the exploitation of two uranium mines which are now in the research stage. About one hundred and fifty workers are at present employed in those facilities. An health physics surveillance program is under way and has been designed to fulfill the requirements due to the future exploitation of the two mines. A complete evaluation of the total dose (external + internal) received by the workers will be given together with a detailed analyses of the technical methods employed for such evaluations. The external doses are evaluated on the basis of individual TLD dosimeters, while the evaluation of the internal doses is mainly due to an enviromental survillance program of the radon and radon daughter air concentration inside the mines. The criteria established for the assessment of the sampling procedures, sampling intervals and dose evaluation related to the radon doughter exposure are reported. The external dose received by the workers are lower than 0.2 m Sv~month and the internal exposure less than 6.4 IO-3 J.h.m-3 /year or using the old units 2 WLM/year.

Jan 1, 1981

By M. A. Marticorena, R. Stratton-Crawley, C. I. Basilio

Diethylenetriamine (DETA) is a selective depressant for nickeliferous pyrrhotite during pentlandite flotation. Laboratory flotation tests conducted on ore and process samples showed that pyrrhotite rejection is greatly improved by small additions of DETA; however, the effectiveness of this depressant is most noticeable when the mineral sample is oxidized. LIMS and XPS analyses conducted on flotation products and pyrrhotite specimens showed that the difficulty in pyrrhotite rejection arises from inadvertent activation of the mineral by heavy metal ions, such as Ni2+, cu2+ and Ag+, that are present in the process water. In the presence of DETA, however, the mineral is deactivated under oxidizing conditions. The deactivation mechanism may involve oxidation of the activation products, which are likely in the form of heavy metal sulfides, followed by solubilization by DETA. FTIR spectra of pyrrhotite electrodes contacted with DETA showed no trace of the reagent on the surface, substantiating the view that its role is one of complexing agent that enhances the dissolution of activation products under oxidizing conditions. FTIR spectra of pyrrhotite contacted with amyl xanthate solutions showed that both dixanthogen and iron xanthate are formed on the surface, the latter becoming more predominant at higher potentials. In the presence of DETA, however, only a small amount of xanthate is adsorbed on the mineral at potentials (Eh) approximately 200 mV higher than the case without DETA.

Jan 1, 1995

By Michael J. Shulman

During-all phases of exploration limited resources must be allocated among exploration methods and among exploration prospects. This problem,, an exercise in optimization, can be treated mathematically. For three objective functions - maximizing return, return to cost and return minus weighted cost - theoretical results exist which enable the exploration planner not only to gain valuable insight into the problem, but also to estimate the resources necessary and to allocate these resources for' at least-two stages of exploration prior to initial field work. A two-stage exploration strategy for volcanogenic-sedimentary iron in northern Egypt illustrates, how the results can be used. Stage 1 consists of an aeromagnetic survey to map the structure of five areas;" stage 2 consists of field reconnaissance work. For the three objectives, lower bounds are calculated as a function of exploration expenditures for each stage in order to facilitate the choice of an-optimal exploration budget. Nomograms are then presented which, based on the Kuhn-Tucker Conditions', enable the incremental allocation of airborne and reconnaissance effort among the five areas.

Jan 1, 1989

By Thomas A. Wheeler, Robert O. Keys

The choice of the flotation reagent that suits a particular coal has become more complicated with the development of new, more efficient reagents. Frothers and conditioning reagents, in particular, have experienced a dramatic reevaluation of their role in floating various types of coals. This paper offers a better understanding of how each of the following factors contributes to the reagent selection: 1. Natural Flotability 2. Degree of Oxidation 3. Size Distribution 4. Percent Solids in Feed Slurry 5. Fluctuations in Plant Feed 6. Limitations on Froth Handling 7. Clean Coal Specifications 8. Ash Content in Feed a) discrete ashable minerals b) inherent ashable minerals 9. Water Chemistry 10. Petrographic Composition of Coal 11. Free-Swelling Index 12. Convictions of Customer The application of conditioning reagents - both promoters and emulsifiers can substantially improve the coal recovery. Some low-rank, hydrophylic coal, previously considered unfloatable can be economically recovered with the use of the proper reagent.

Jan 1, 1986

By B. J. Arnold

Coal froth flotation cells typically receive little attention in coal preparation plants. They process only a small portion of the total coal feed (perhaps 5-1 0% of the total plant feed in the United States), they are viewed as a way to take the load off the refuse thickener, and their operation is not well-understood by cleaning plant operators. Operating parameters are set based on the equipment supplier information, and reagent dosages are set at the recommendation of the latest chemical vendor. The cells then operate day in and day out, recovering coal and producing a product that may not meet ash or sulfur specifications or that may be the wrong percent solids for downstream dewatering operations. If improvements can be made to this circuit, then the whole plant will benefit. Paying attention to rate and residence time and the wealth of data from the literature or from a series of targeted laboratory tests can give operators the key to improving the performance of froth flotation cells AND overall plant performance. This paper provides an overview of froth flotation rate and residence time data and gives practical suggestions for specifying and using laboratory tests to improve froth flotation performance. Suggestions for improving froth cell performance are also given based on available literature data.

Jan 1, 1999

By Takashi Sakaguchi, Akira Nakajima

Some attempts were made to recover and remove heavy metal elements, such as uranium, copper and chromium, from aqueous systems by using several phosphate compounds. The phosphorylated derivatives of polysaccharides, chitin phosphate, chitosan phosphate and cellulose phosphate, have high abilities to accumulate heavy metals, such as uranium, copper, manganese, cobalt, cadmium, zinc, nickel and chromium, compared with non-phosphorylated polysaccharides. In order to obtain basic information on the recovery and removal of uranium that may be present in industrial effluents, mine waste water and seawater, the adsorption of uranium by chitin phosphate and chitosan phosphate was investigated in details. The adsorption of uranium by chitin phosphate and chitosan phosphate was much greater than copper, cadmium, manganese, zinc, cobalt, nickel, magnesium and calcium. The adsorption of uranium was very rapid and was affected by pH of the solution, temperature. granule radius and co-existence of carbonate ion. The amounts of uranium adsorbed on the adsorbents increased linearly as the external uranium concentration increased. Uranium adsorbed on chitin phosphate easily desorbed with diluted sodium carbonate solution. On the other hand, uranyl and cobalt ions were separated from each other by using chitin phosphate. Along with these fundamental research, some attempts were made to recover uranium from seawater.

Jan 1, 1993

By John J. Reed

The 1945 fire at the Braden (El Teniente) Copper Mine in Chile took 354 lives, and ranks as the most lethal metal mine fire in history. The mine was developed in the wall of a canyon over 900 m (3,000 ft) deep. Principal entrance was through a main haulage adit at the canyon bottom, and up through two internal shafts. Mining was by block caving from the top of the orebody with most of about 900 men on shift working in three production areas. Ore was transferred by gravity to the haulage level through a complex system of ore passes with associated ladderways. Normal mine ventilation was incast through numerous level portals and up- cast through the shafts and raises. The fire was confined to a maintenance shop just inside the portal of the lower production level. Smoke, gases and flammable vapors were drawn into the mine, and a subsequent explosion of the gases destroyed an air door and injected carbon monoxide into the workings. Falling water in a drainage raise near the fire made it downcast, which carried gases down to all the lower levels where they were drawn into the levels and then up connecting raises. Miners attempting to escape by climbing down the ladderways from the production levels were met and killed by the rising gases.

Jan 1, 1989