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By Louis W. Cope

The Compañía El Zapote Yacimiento Y Minas, S.A. has an ore body containing 650,000 tons of 0.185 oz/t gold ore in Mexico. Metallurgical testwork has been done to determine the response of this ore to several possible processing schemes. The paper describes the rationale for selecting the Silver State Mining Co. methods in Colorado. Plans for developing the mine and building the treatment plant are described in detail in the paper. Estimates of capital and operating costs are included.

Jan 1, 1984

By Glenn M. Boyce, Timothy R. Coss

Microtunneling first appeared with some regularity in the United States in 1987. Until then, only Japan and Germany utilized this method of construction. Its high costs initially limited its application to special situations. The last ten years have seen the use of new pipe materials, new machines, new cutterheads, new techniques, and an average growth of30 percent each year. This paper documents the growth and changes that have occurred with microtunneling. Based on current industry practices and advances from abroad, this paper postulates what the next ten years may hold.

Jan 1, 1997

By J. A. Finch

The use of pneumatic methods for measuring interface level in flotation columns is analysed. It is shown that errors can vary over a wide range (e.g. 40 cm. in one industrial application) depending on bubble size, particle size, bubble loading, liquid hold-up and bulk slurry density. Accurate measurements (+ 5 cm) can be obtained by measuring intensive properties of the froth near the interface. Methods based on the measurement of temperature and conductivity are described and analysed. Control of the interface level using these measurements subject to various disturbances is demonstrated.

Jan 1, 1988

By T. Shungu, N. Vermaut

The various copper-cobalt ores mined by Gecamines, together with typical plant applications and results, are briefly described. Intensive laboratory investigations have been undertaken in recent years to improve the metallurgical performances of the various concentrators. As a result of these tests, it was shown that the flotation of the siliceous oxide ores could be improved by increasing the efficiency of the palm oil collector (energetic conditioning, chemical emulsifier, petroleum sulfonate addition) and by varying the froth depth in the cells. A new flowsheet incorporating these modifications and a regrinding stage has been approved for the rehabilitation of the Kolwezi concentrator. For what affects dolomitic oxide ores, hydroxamates were tested as secondary collectors and, based on successful laboratory results, plant trials were run but failed due to excessive frothing. In other plant tests, xanthates were replaced by a xanthate- fatty acid mixture; plant trials over more than one year proved successful for copper, but not for cobalt. Mercaptans were tested as secondary collectors for the sulfides flotation from sulfide or mixed oxide-sulfide ores; laboratory results proved successful but, to date, no plant test has been run.

Jan 1, 1987

By J. W. Danni

Today's mining industry faces many challenges. Perhaps none is more important than the challenge of improving our industry's public image. Opinion polls document public concern for a clean and safe environment. As part of that public, the mining industry must share that goal. The public is now the most powerful environmental group in society. And the public wants the environment to be protected. In May 1989, Edgar S. Woolard, chairman of DuPont, spoke to the American Chamber of Commerce. He said that industry's continued existence "requires that we excel in environmental performance and that we enjoy the non-objection - indeed even the support of the people and governments in the societies where we operate." In effect, Woolard called for "corporate environmentalism." He defined it as an "attitude and a performance commitment that places environmental stewardship fully in line with public desires and expectations." Environmentalism is no longer a fringe activity, but rather is now clearly in the mainstream. How can we meet public expectations and improve our image as an industry? One of the best ways is to plan, design and operate our mine facilities with environmental responsibility and social concern. The Mineral Hill Mine provides a good case study of a facility that has made this commitment. The project used an inter-disciplinary, multiagency task force, citizen advisory groups and engineering and design considerations. As a result, Mineral Hill achieved cost-effective permitting. At the same time, the operation demonstrated effective "corporate environmentalism."

Jan 1, 1992

By Michael Honerkamp, Clemens Mann

A quarry is not a static, but a dynamic structure that greatly affects the appearance of the surrounding area. Excellent planning is required today to cope with this continual change. In this paper several case studies are presented where computerized three-dimensional visualization has been successfully applied.

Jan 1, 1996

By R. G. Reddy

Iron solubility's in spent pickling (HFHNO3 -H2O) solutions were determined as a function of HF and HNO3 acid concentrations. A chemical analysis of the industrial pickling solutions and sludges was performed. The stable phases observed in the sludges are FeF3.3H2O and (FeCr)F3.3H20. Pure Fe metal, AISI 316 stainless steel and AISI 416 stainless steel were used in this study. The results show, that the solubility of Fe increased as the concentrations of HF increased in the pickling solution at a fixed concentration of HNO3. A reasonable agreement between the experimental solubility data and the theoretical calculated data was obtained. X-ray diffraction analysis showed that the solid solubility product formed in the ternary solution containing pure Fe is mainly, at a high pH value, FeO(OH) compounds and, at a low pH value, Fe F3.3H2O compounds.

Jan 1, 1994

By J. A. Finch

The photographic measurement of bubble diameter is tedious and restricted to vessels with transparent walls and relatively low bubble concentrations. A new method for predicting bubble diameter in a flotation column has been developed and confirmed by comparison with measured mean bubble diameter (Yianatos et al., 1987) Flotation columns are not mechanically agitated. This note describes an extension of Ms method to a mechanically agitated flotation machine. A recent publication by Szatkowski (1987) provided sufficient data to calculate bubble diameter by the proposed method and compare with values determined photo- graphically. Method In a two-phase system (gas and liquid), bubble diameter (db), superficial gas rate (Vg) and liquid rate (Vl), and gas holdup (Eg) are linked by two relationships (see the nomenclature at the end of the paper for definitions of symbols). [ ] Equation 1 is the definition of slip velocity (relative gas to liquid velocity) for a countercurrent gas-liquid system, and equation 2 is an adaptation (Yianatos et al., 1987) of the expression of Masliyah (1979) for hindered settling in a multispecies system. The solution for bubble diameter is by repetitive substitution of estimates of db in equation 2 until the calculated Ubs is equal to the measured Ubs in equation 1. Results and discussion Table 1 presents the data obtained by Szatkowski (1987) from a mechanically agitated laboratory flotation machine. The machine generated bubbles by directing a gas stream into the vicinity of a disk rotating at Ngh speed (up to 8000 rpm) in the flotation slurry. The air was completely dispersed in a swarm of fine bubbles. A photographic technique was used to determine the distribution of bubble size. The mean diameter and standard deviation were then calculated. Table 1 provides all the information necessary for computing bubble diameter (Vl is assumed zero). The calculated bubble diameter is presented in Table 1 as d;. Figure 1 plots measured versus calculated bubble diameter and shows reasonable agreement between values. There is an apparent tendency to undercalculate the small bubbles and overcalculate the large ones.

Jan 1, 1987

By Donald C. Trueblood

Since the Surface Mining Control and Reclamation Act (SMCRA) was passed in 1977, coal mine reclamation has been restricted from utilizing bluff-1ike features in permanent reclamation. This restriction is based on those provisions of SMCRA which require the elimination of all highwalls. In 1987, the Wyoming Mi ni ng Association began an effort to acquire the ability for coal mines to utilize bluffs in permanent reclamation for the purpose of enhancing the post-mining land use. The regulatory reform approach being uti1ized includes formation of a work group with members from industry, government, agriculture, and environmental organizations to prepare a proposal. Advantages of this approach are discussed.

Jan 1, 1989

By V. A. Leach, Lokan. K. H., S. B. Solomon, R. S. O’Brien, L. J. Martin, K. N. Wise

INTRODUCTION The development during 1979 of a relatively small, but high grade (10,000 tonnes uranium at an average grade of 2 per cent), uranium ore body at Nabarlek in the Northern Territory, Australia offered an excellent opportunity to obtain detailed radiation data for an open cut mine operating during the dry season. The ore body (Queensland Mines Limited-1979), which was completely extracted in a period of four and a half months, consisted of a vein type deposit dipping at 30 to 45 degrees and contained a central core of pitchblende in massive and irregular pods, surrounded by lower grade fine grained disseminated pitchblende. Mineralisation extended from the surface to a depth of 72 metres over a length of 230 metres with an average but variable thickness of 1D metres. Ore near the surface had been heavily weathered and complex secondary minerals were formed which had dispersed from the main vein. Mining was carried out with large earth moving equipment. Overburden and weathered surface ore were removed initially with scrapers. At greater depths bulldozers were used to rip and assemble ore and rock at each level, and these were removed by large trucks to the ore and waste rock stockpiles. Where necessary, blasting took place during shift changes each evening. Mining was essentially continuous with two ten hour alternating shifts working for thirteen days out of fourteen. At the completion of mining a relatively small excavation (335m x 185m x 70m) remained, and this will serve as a tailings repository during the milling phase. FIELD MEASUREMENTS The inhalation of radon daughters, arising from the radioactive decay of radon gas is well established (Archer et. al. 1973) as a potential hazard in the uranium mining industry. Control over radon and its daughters to ensure that recommended exposure limits are not exceeded is achieved by providing adequate ventilation, and under normal circumstances natural ventilation from an open pit should be sufficient. However, during the dry season it is not uncommon for stable atmospheric conditions, with little horizontal air movement, to develop - particularly at night - and significant radon daughter concentrations may accumulate. Throughout the entire mining period measurements were therefore made of radon and radon daughter levels at representative locations within the pit and on the ore stockpile as it developed. Initially these measurements were carried out manually, using the Rolle method for radon daughters, (Rolle 1972) and .scintillation cells (Lucas 1964) or a two filter tube for the determination of radon (Thomas 1970). For the latter half of the period however, a continuous recording instrument, developed within the Laboratory was used to provide a detailed record of radon daughter levels within the pit. At the same time, continuous readings of wind speed and direction, and vertical temperature gradient between 10 and 3D metres were recorded on a 30 metre meteorological tower, situated 800 metres from the pit. Radon Emanation Rates It is evident that radon and radon daughter concentrations depend on the grade, or more particularly, on the surface radon emanation rate of the ore which is exposed. Accordingly, as the mine progressed, detailed measurements were made of both of these quantities. The surface emanation rate of radon was determined for each ore bench as it was exposed by placing an extended array of canisters, filled with freshly degassed activated charcoal, face down on the ore for a known time. These canisters, which had previously been calibrated in the Laboratory, adsorb radon with high efficiency, and the total radon adsorbed is measured after retrieval by detecting the gamma rays from the trapped radon daughters (Countess 1977). At the same time, as each canister was placed in position, a measurement of the local ore grade was made for each location. This was achieved with a calibrated sodium iodide scintillation detector, adjusted to detect the 609 keV gamma ray from the isotope 2148i, a decay product of radium. Finally, measurements were made of the radiation field 1 metre above the surface, with a gamma ray survey meter, which was calibrated in the Laboratory. The relationship between the scintillator count rate and ore grade was determined by comparing the scintillator output with the gamma monitor, and relating the latter measurements to ore grade (Thomson and Wilson 1980). It was observed that while emanation rates and ore grades varied widely, the ratio of emanation rate to ore grade was in general fairly stable. A plot of this ratio is presented as a function of depth below the original surface in Figure 1. For most observations the ratio is constant at a value of 80 Bq m-2 s -1 per unit ore grade, where ore grade is expressed as percentage of U308. At the surface however, where the ore was weathered, the ratio was about a factor of three higher, and at two particular depths, where high grade pitchblende was being removed, it was very much lower. This was not unexpected as earlier Laboratory studies of drill core samples from Nabarlek had indicated that the emanation coefficient (the fraction of radon produced within the ore which escapes from the mineral particles) decreases with increasing ore grade.

Jan 1, 1981

By L. Laage, R. Greur, W. Pomroy

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 US Bureau of Mines and Michigan Technological University 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, 1995

By Li Changgen, A. Bahr

The adaptability of pneumatic flotation cells for the flotation of sulfide ore and the conditions for sulfide ore flotation in pneumatic cells were investigated. The advantages of pneumatic flotation cells over mechanical flotation cells, as well as flotation columns, for the flotation of sulfide ore were demonstrated. Test results indicated that the Cu grade and recovery for concentrates obtained when using the pneumatic flotation cell were 1 % to 2% and 4%, respectively, higher than those obtained when using the mechanical flotation machine.

Jan 1, 1993

By L. A. Puchkov

The creation of automatic methane concentration control systems presupposes the use, as a control factor, of the air rates in workings and in mine as a whole. These systems present a complicated set of computers and software, including as major components the following - systems for detecting methane concentration and air rate; - telemechanics systems; - programs and means of data processing; - programs and means of air rate control in workings and main fan capacity control. The paper analyses the experience of development and exploitation of automatic methane control system in gassy mines of the USSR Donetz coal basin. Much attention is given to the study of technological factors influence upon aerogasdynamic process using automatic methane control system.

Jan 1, 1989

By Kenneth R. Miller

Surface mine equipment operators in the Campbell County region of Wyoming's Powder River Basin have found new ways of solving old problems. Technology, experience, competitive pressures and an increasing grasp of economies of scale have driven mine operators, equipment manufacturers and suppliers to specialization of applications. In economic terms, today's coal price of $4.95/t ($4.50/st) equates to $2.53/t ($2.30/st) in 1980 terms - an incomprehensible value at that time. This article describes some examples of change and adaptation made by Powder River Basin coal operators in overburden stripping equipment and techniques. It focuses on the evolution of the design and use draglines, shovels, trucks, scrapers and dozers.

Jan 1, 1998

By Sol Ribakoff

With the utilization of most of the "high dam" sites for hydro-electric power and the completion of most railroad routes, many tunnel contractors were extremely doubtful that tunnel driving would continue to be an important element of heavy contracting. Experience has proved otherwise. The ever-increasing need for rapid transit and for pollution control have generated, and will continue for the indefinite future to generate, a very high level of tunneling activity. At the same time, the costs of construction have traveled an upward curve in the tunnel industry, as in all other types of construction. As a result, Owners, Engineers and Contractors have sought ways and means of constructing more economically through the development and use of labor-saving devices and techniques. The development of mining machines and lasers has contributed tremendously to such economy. Before giving you a contractor's viewpoint on Owner-Engineer-Contractor relationships in tunneling, it may be well to provide some background as to matters which give rise to that viewpoint. Construction contractors in general, and tunnel contractors in particular, have always had to contend with the physical environment in which the work has to be accomplished. However, when a building contractor has constructed his foundation, and certainly after he has "closed in", he deals thereafter with known physical conditions, or at least with conditions which he could reasonably have estimated would occur. Except, perhaps, for the hazard as to earthquakes, he has cleared Nature's threats. A tunnel contractor, however, must give thought to what the physical environment may do to his job, each and every day that he is driving a tunnel. The general consensus among tunnel men is that Mother Nature is much more likely to be murderous than motherly. Without attempting to make too much of

Jan 1, 1997

By André G. Journel

As opposed to graphics applications in medical sciences and mechanical engineering, computer imaging of the subsurface faces a severe problem of data shortage. Most graphics softwares include an interpolation algorithm aimed at producing slick graphic output, irrespective of the attribute being interpolated, the quantity and quality of the data available, and what the map is intended for. It is suggested that the power of modern computers be also used in providing representations of the subsurface that accurately reflect actual spatial variability and the large variety of soft information available beyond hard data. Since any subsurface representation is uncertain, a measure of that uncertainty should be provided which can be used for risk analysis.

Jan 1, 1992

By Jacob Feld

Introduction The best way to eliminate the possibility of rapid excavation in tunnel work is to start an argument between Owner Engineer and Contractor. And arguments are readily started when work is progressed without a frank open agreement on the rules of the game. Fifty years ago a tunnel contractor took a job to excavate and line a tunnel, providing all labor and materials under the guidance and continuous instruction of the Engineer who provided all survey work, checked each new heading and set the lines for the next round of drill holes, usually designed and ordered protective measures, kept record of progress and controlled payment for the work. In my first job in a tunnel, muck cars were loaded by hand and hauled by donkeys. Progress was, at today's criteria, not rapid. The Contractor or in the case of a large concern, his executive field representative was always at the site, knew most of his men by name, and there was a mutual feeling of respect between him and the Engineer in charge of the work. Misunderstandings were cleared up when they came up, expeditiously and fairly, even though satisfaction was not always expressed. The Owner came for the ground breaking and usually for the holing through shot. The Owner had full reliance on the Engineer's ability and integrity. The Engineer recognized the Contractor's expertise in being able to man the job and produce results.

Jan 1, 1974

By Timothy Batchler, Khaled Mohamed, Morgan Sears

The National Institute for Occupational Safety and Health (NIOSH) initiated a testing program to assess the effects of lateral loading on various standing supports used in underground coal mines. This study is not intended to endorse a particular type of standing supports nor to provide a comparison between different types of standing supports. This paper aims to measure the lateral loading capacity of two types of standing supports and evaluate how it affects their vertical loading capacity and yielding mechanisms. The study utilizes the Mine Roof Simulator (MRS) at NIOSH Pittsburgh. Type-1 support is characterized by telescopic tubes made from ASTM A-513 steel with a specified locking mechanism, and Type-2 support comprises a single component constructed from ASTM A500 Welded Grade C pipe. Vertical load tests were carried out to assess the designed performance of Type-1 and Type-2 props. Type-1 props demonstrated a "constant yielding" behavior, achieving an ultimate capacity of up to 140 kips. Type-2 props showed a "load shedding" behavior, reaching peak verti- cal loads of up to 191 kips. Buckling analysis revealed that Type-1 props were not designed to buckle, and Type-2 props failed due to buck- ling rather than material yielding. Under vertical pre-loading, lateral loading tests showed that Type-1 props can withstand about 9 kips, and Type-2 props can withstand about 10.79 kips of lateral load. This represents roughly 6% of their vertical loading capacities. Testing props under lateral loads in addition to their intended vertical loads showed that the lateral loads could influence their loading mechanisms. Type-1 props did not exhibit the expected "constant yielding" behavior under lateral load but instead showed "load shedding" decreasing their rated vertical capacity by 70%. At high vertical pre-loading, Type-2 props demonstrated "constant yielding" behavior instead of the anticipated "load shedding," leading to a 60% reduction in their rated vertical capacity. These findings provide valuable insights into the behavior of these props under different loading conditions, aiding in their efficient use and design in underground mining operations.

Jun 25, 2024

By M. Lotfi

The criteria for evaluating equipment operator performance were identified as the changes in reaction time, the changes in physiological responses, and the changes in subjective reporting of stress. Data were collected while the Subjects operated a front-end loader simulator. This report out-lines the components and the tasks generated by the simulator. It explains the simple and basic assumptions underlying the design of the simulator and the methods of data collection. Improvements that can facilitate the collection of data, including the connection of the simulator to a portable personal computer for on site use are discussed. Statistical analysis of data showed significant deterioration in performance. The report concludes that operator performance can be measured and improved. This report shows that the operator tasks can be simulated by means of simple simulators, the complexity of which is determined by the availability of funds and the area of interest of the investigator.

Jan 1, 1989

By Gun Berglund, Eric Forssberg

Sulphide mineral flotation is known to be affected by oxidation-reduction conditions in the pulp, although there is some doubt as to whether it is the oxidizing environment or the type of oxidant which influences flotation. Variations in the oxidizing conditions of the pulp and their subsequent effect on flotation were examined for two types of natural sulphide ore, a galenasphalerite ore and a complex pyrite ore. Different gas mixtures ranging from pure nitrogen to pure oxygen were used to control the oxidizing conditions. Zinc recovery increased with a more oxidizing environment, and nitrogen gas acted almost as a depressant for sphalerite in the flotation of the Pb-Zn ore. For the complex pyrite ore, the selectivity between chalcopyrite and both gangue and pyrite improved when the environment was oxidizing, resulting in higher Cu recovery in the copper rougher concentrate. The use of an oxygen rich flotation gas was found to be a suitable method for changing the oxidizing conditions and improving flotation under controlled conditions. The flotation results were correlated to the oxygen content and the redox potential, parameters which describe the pulp chemistry conditions.

Jan 1, 1989