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By R. E. Doerr

The successful technical demonstration of coarse coal slurry transportation at Consolidation Coal Company's Loveridge Mine in West Virginia suggests that it is now appropriate to seriously consider this technology in other applications, especially the transport of ' coal in surface mining. Early examination indicates that coarse coal slurry transport may be highly competitive with existing haulage systems, depending on a number of factors. These factors are not yet completely defined, but certainly will include production rates, coal physical and chemical properties, terrain, soil conditions, climate, water availability and quality, availability of skilled labor and other economic considerations impacting the existing haulage systems.

Jan 1, 1983

By Antti J. Niemi

Radioisotope tracers have so far been used for extraction of residence time distributions of flotation devices. They have also been proven applicable to evaluation of rate coefficients k of industrial flotation. It is now shown how values of k are scaled up on the basis of laboratory data on flotation and chemical conditioning, and of laboratory testing of samples from output of industrial conditioning vessel. Subsequently a model of conditioning and flotation is obtained which may be used for simulation and control of the steady state of the combined process. Discussion extends to modelling, simulation, CAD and opti- mization of flotation plants with re- circulation, and of ore dressing systems which consist of grinding and flotation plants.

Jan 1, 1990

By C. E. Stack

For the purposes of this presentation, "refractory clay" is intended to include any clay suitable for refractory products and thus represents a description based on industrial application. Other common examples based on use would be white-ware clay, bleaching clay, paper clay, or cement clay. Most users and producers of refractories have specific quality requirements which determine the quality or type of clay that can be utilized. Many clays can however be interchanged or substituted in use by changing manufacturing processes or upgrading less desirable clays. U.S. Bureau of Mines publications (Ampian, 1985) categorize days into six groups. These are kaolin, fire clay, ball clay, bentonite, fuller's earth, and common clay. These are practical groupings based on clay production and usage in the United States. Among these groups bentonite, fuller's earth, and common clay are primarily composed of the minerals, smectite, illite, or chlorite, and are non-refractory. Kaolin, ball clay, and fire clay are commonly used in refractories and thus qualify as refractory clays.

Jan 1, 1986

By Ronald L. Haxby

This report presents a refractive seismic technique for evaluating the strength of rock within an open pit bench. A concept of correlating rock strength and seismic velocity is discussed and a method of predicting the degree of fragmentation of a pit bench is introduced, Figure 1 shows the area of interests [ ] Most of the work was performed while completing graduate studies at the University of Arizona.

Jan 1, 1967

By John C. Nigro

Bench scale and pilot plant research was conducted using dolomites (CaO,MgO) lime as the basic additive in the preparation of self-fluxed pellets from a typical magnetic taconite concentrate (5.57 S_2). The specific objective of this investigation was to ascertain the viability of the magnesia lime pellets in high temperature oxidizing and reducing atmospheres. Pellet basicity and induration temperature were major parameters affecting fired pellet quality; temperatures ranging from 1,200° to 1,250" C appeared to be the most favorable for production of self-fluxed pellets with basesities (B) above 1.0. Comparison of the mechani¬cal and metallurgical properties of regular (acid) and self-fluxed pellets (B 1.55) produced under similar conditions in a modified grate pelletizing machine showed that the self-fluxed pellets were more resistant to abrasion and to high and low temperature reduction disintegration, an important consideration in commercial application. The Plus 3 mesh Linder index increased from 68 percent (regular pellets) to over 90 percent (self-fluxed pellets). The reducibility and swelling indices of the self-fluxed pellets were found to be comparable to the regular pellets.

Jan 1, 1972

By M. C. Williams, T. P. Meloy

With the increasing power of computers to simulate and control processes in the mineral industry, predicting the potential use of computers in the minerals field is not a hazardous enterprise, but predicting the timing of their use is. Like the railroad industry, technology invades the mineral industry, rather than being an industry like electronics that creates technology. Because of this invasive nature of computer technology in the minerals field, this paper predicts what will be possible to do effectively and economically with computers in the mineral industry. Moreover, this paper explores the problems of using the emerging computer technology in the mineral industry. For example, if not now, it soon will be possible to control the output of a mineral processing circuit - high grade, high flow or a mixture of it - to meet the daily market conditions and to sell each day that daily "mill" output as "mill" futures on the commodity market. Finally, suggestions are made which may be done to prepare the industry for the computer revolution in the mineral industry.

Jan 1, 1993

By Ireneusz Tomza, Jolanta Lebecka

INTRODUCTION Radioactive deposits were observed in 1972 in some of the Upper Silesian coal mines. They were located mainly in the drains in galeries and on the inside surfaces of water pipes. They also caused some problems by accumulating in water pumps. It has been postulated that the deposits are produced by natural radioactive waters seeping from the rocks. Investigations were initiated to answer the following questions: - What is the composition and the amount of radioactivity in the deposits? - What radioisotopes are present in the water? - How are the radioactive deposits formed? - Do the radioactive waters also occur in other mines? - How does the radioactivity of the water depend on chemical composition? - What is the origin of the radioactive water? - Does the water and the deposits cause radiation hazards for miners? -How can the radiation hazard be reduced? METHODS OF MEASUREMENT Determination of Radium Isotopes in Water The commonly used methods of radium determination in water are either based on measurements of the radioactivity of 222Rn which is in equilibrium with 226Ra, or on the detection of alpha particles of the radium radioisotopes after chemical separation of radium from the water sample. The method based on radon activity measurements is very sensitive and does not require any chemical Separation, but it can be used for determination of 226Ra from the uranium series only, because the thorium daughter 220Rn has too short a half-life (55s to yield the required accuracy. The method developed by Goldin, 1961 [2] involved alpha-particle measurements in thin layers of RaS04 and BaS04 separated from the water. This method is not convenient for saline water and water with high barium concentration because the amount of barium carrier in this case is too large to obtain a thin layer of precipitate with sufficient activity. The Upper Silesian carboniferous waters are often saline with high barium content, so the method described by Goldin was not convenient for this case and it was necessary to change the detection system and modify the chemical preparation. The procedure developed by the authors for the determination of radium isotopes in water was as follows: - Depending on the Ba2+ content and the required sensitivity of measurement, a water sample of 200 cm3 to 3 dm3 was taken. - 10 cm3 of 0.25 M citric acid and 5 cm3 15M ammonia was added to form complex Ba2+ ions and avoid the immediate precipitation of BaSO4. (This was repeated as long as the addition of BaC12 did not form a precipitate.) - 1 cm3 of 1N solution of Pb(N03)2 as a carrier for radioactive isotopes of lead and 10 cm3 of 0.1 N BaC12 as a carrier for radium were added. - The sample was heated to the boiling point and the precipitation of RaS04, BaSO4 and PbS04 with 50% H2SO4 was carried out. - After several hours the sample was centrifuged and the precipitate was purified by washing with nitric acid and distilled water. - The precipitate was then redisolved in 20 cm3 0.125 M Na2EDTA and 3 cm3 6M ammonia and reprecipitated from the solution by dropwise addition of acetic acid to d pH of 4.5. At this value of pH, precipitation occurs only for the barium and radium sulfates, while lead and all other radioactive elements remain in the solution. The date and time of deposit precipitation was recorded. - The final barium-radium sulfate mixture was washed with distilled water and transferred to standard measurement vials. - Each vial containing a deposit had 6 cm3 of distilled water added and was then shaken vigorously. 12 cm3 of liquid gelling scintillator (INSTA-GEL UNISOLV-1 type) was then added and the vi 1 was shaken again. After a while the scintillator turns into a milky gel in which the deposit is uniformly distributed. - The standard sample of 226Ra was prepared in the same way. - The activity of the samples was measured using a liquid scintillation spectrometer. (In this case the TRICARB 3320 produced by Packard Instruments, was used). Tests run on standard radium solutions provided by Amersham Radiochemical Centre indicated that this method of measurement enables one to achieve an efficiency of almost 100% (within measurement error). For alpha particles no quenching effect was observed for the BaS04 concentration in the range up to 80 mg of BaS04 per 1 cm3 of liquid scintillator coctail (Fig. 1). This provides a sensitive determination of radium in water with high barium content and also in saline water. In saline water the solubility of barium sulfate is much higher than in

Jan 1, 1981

By Alan Bauer

In recent years there has been increasing interest in employing the technique of explosive casting in strip mines. Explosive casting, applied to dragline mining, describes the procedure whereby the overburden is horizontally displaced by blasting causing a portion of the material to be thrown into the previously mined cut. Therefore, it is not necessary to subsequently excavate this waste with the stripping equipment. In addition, allowing the overburden unrestricted movement during the blast most often results in improved fragmentation and enhanced machine productivity. The method is receiving attention because the capital and maintenance costs of stripping equipment has risen rapidly in relation to explosives costs. Improved productivity is necessary to maintain unit costs at an acceptable level.

Jan 1, 1983

By Ralph P. Hackl

Ore at the Congress gold property, located near Goldbridge, British Columbia, is extremely refractory with most of the gold disseminated in fine-grained arsenopyrite. Metallurgical testwork conducted by Giant Bay Biotech Inc. indicated that biooxidation pretreatment was capable of increasing cyanide gold recovery from the ore to greater than 90%. To determine if the bioleach process could be successfully scaled up, a 225m' (7950-cu ft) commercial size bioleach reactor was built and tested at the mine site in 1989. At that time, the tank was the largest bioleach reactor ever operated. The objectives of the program were: • to ascertain if the biooxidation rates obtained in lab and pilot-scale reactors could be duplicated in a commercial scale tank; • to identify agitation conditions under which the process will function optimally; and • to demonstrate the bioleach process on a scale sufficient to satisfy the owners and potential investors.

Jan 1, 1990

By Y. J. Wang

The selection of a shaft size for ventilation purposes is a classic problem of concern to mining engineers. This presentation is concerned with the sizing of conventionally-sunk circular shafts with concrete or shotcrete linings. Costs of sinking shafts of three different depths (from 500 feet to 1000 feet) and six different diameters (from 14 feet to 24 feet) were obtained through questionnaires to shaft contractors. The primary objective of the economic model presented is the balancing of detailed annual capital and operating costs to achieve the minimum overall cost of the shaft installation over its life. The economic model is similar to previous analyses but treats several of the individual cost categories in an updated fashion. Included in the paper is a detailed analysis of the effects of varying power costs on optimal shaft size. Also included are a statistical analysis of current shaft costs and comments on the choice between shotcrete and concrete linings.

Jan 1, 1977

By R. W. Williams

Consequent on the development of digital computers the importance of analog simulation as a means of studying engineering problems has diminished in recent years. The general-purpose nature of a digital computer ensures its applicability to a wide range of tasks whereas an analog simulator is confined to the one specific use for which it was designed. Nevertheless the analog technique remains attractive in its application to certain aspects of the study of mine ventilation networks, for reasons which will now be developed.

Jan 1, 1980

By Michael Fehler, Hidenshi Kaieda, Leigh House

Hydraulic fracturing has gained in popularity in recent years as a way to determine the orientations and magnitudes of tectonic stresses. By augmenting conventional hydraulic fracturing measurements with detection and mapping of the microearthquakes induced by fracturing, we can supplement and independent1 y confirm information obtained from conventional analysis. Important information obtained from seismic monitoring includes: the state of stress of the rock, orientation and spacing of the major joint sets, and measurements of rock elastic parameters at locations distant from the wellbore. While conventional we1l 1ogging operations can provide information about several of these parameters, the zone of interrogation is usually limited to the immediate proximity of the borehole. The seismic waveforms of the microearthquakes contain a wealth of information about the rock in regions that are otherwise inaccessible for study. By reliably locating the hypocenters of many microearthquakes, we have inferred the joint patterns in the rock. We observed that microearthquake locations do not define a simple, thin, planar distribution, that the fault plane solutions are consistent with shear slippage, and that spectral analysis indicates that the source dimensions and slip along the faults are small. Hence we be1 ieve that the microearthquakes result from slip along preexisting joints, and not from tensile extension at the tip of the fracture. Orientations of the principal stresses can be estimated by using fault plane solutions of the larger microearthquakes. By using a joint earthquake location scheme, and/or calibrations with downhole detonators, rock velocities and heterogeneities thereof can be investigated in rock volumes that are far enough from the borehole to be representative of intrinsic rock properties.

Jan 1, 1986

By P. Bottomley, M. Matthews

Maintaining an acceptable thermal environment in South African gold mines becomes increasingly difficult as mining progresses to greater depths where higher virgin rock temperatures are encountered. Current environmental practice offsets the resulting high heat loads by installing large refrigeration plants. However, with the continued escalation of refrigeration costs, it has become necessary to examine other methods for economically combatting the underground heat load. The Chamber of Mines Research Organization has recently been pursuing a programme to devise methods of reducing the flow of heat into underground workings at source. Although there are several sources of heat (such as machinery, men, and explosives), the most significant is that from the rock mass surrounding the workings (Bluhm et al., 1986a). The main thrust of the work has therefore been directed at predicting and devising methods of reducing this heat source. A great deal of theoretical work has been carried out on the prediction of underground heat flow. From a review of this work (Bluhm et al., 1986b) it became apparent that there are two major aspects which require attention, namely algorithms for predicting the heat flow around the advancing stope face, and a correlation of the theoretical work with accurate empirical data. In order to remedy this situation, new theoretical models have been developed (von Glehn and Bluhm, 1986), and heat flow measurements have been made in both a conventional stope (Bluhm et al, 1986a) and in a backfilled stope (Matthews u., 1987). A number of methods for reducing rock heat flow are being examined. These include the insulation of intake airways (Bottomley, 1985 ), backfilling with waste material of the worked out areas, and alternative approaches to the design of mining layouts, the mining method, and the choice of cooling strategy. This paper highlights the heat load reductions that can be achieved by backfilling the worked-out areas and by adopting concentrated mining. The first part of this paper summarizes the results of the measurements obtained in the conventional and backfilled stopes. The theoretical models are then described and comparisons are made with the measured values.

Jan 1, 1987

By D. R. Wilburn

This summary of international mineral exploration activities for 2012 draws upon information from industry sources, published literature and U.S. Geological Survey (USGS) specialists. The summary provides data on exploration budgets by region and mineral commodity, identifies significant mineral discoveries and areas of mineral exploration, discusses government programs affecting the mineral exploration industry and presents analyses of exploration activities performed by the mineral industry. Three sources of information are reported and analyzed in this annual review of international exploration for 2012: 1) budgetary statistics expressed in U.S. nominal dollars provided by SNL Metals Economics Group (MEG) of Halifax, Nova Scotia; 2) regional and site-specific exploration activities that took place in 2012 as compiled by the USGS and 3) regional events including economic, social and political conditions that affected exploration activities, which were derived from published sources and unpublished discussions with USGS and industry specialists.

May 1, 2013

By L. M. Pero

The paper summarizes aspects of the recent literature on mineral development in the Third World. The emphasis is on publications covering agreements between host governments and mining companies.

Jan 1, 1985

By W. Linwood Haden

Fullers earth has been mined since about 1920 in southwest Georgia and the adjoining area of Florida. In 1935, the mineral was named "attapulgite" after the source of a sample near the town of Attapulgus, Decatur County, Georgia. Mining and processing of the clay was described in a 1930 publication1 at a time when petroleum refiners were the major users. In the years since then, the uses and users of attapulgite have multiplied, and both mining methods and processing methods have been changed to optimize the clay for the new uses. A comprehensive review of the properties and applications of attapulgite 2 has been published. Only a brief review will be given here to explain the properties being sought and to show how these properties are optimized by mining and processing practices.

Jan 1, 1972

By O. Lopez

"Stringent regulations and increased arsenic presence in ore bodies being exploited have created the need for cost effective and environmentally compliant technologies to remove selenium and arsenic from mine waters and metallurgical waste streams. Existing treatment methods have high life cycle costs and/or produce residues that, due to their unknown stability over the long-term, may represent future liabilities. This results in high compliance costs and uncertainties which negatively impact existing operations and projects in permitting. Selen-IX™ is a new ion exchange based process that selectively removes selenium from mine impacted waters down to 1 ppb while producing a stable inorganic iron-selenium product. Results of piloting completed on streams generated from coal and copper-gold deposits are presented along with preliminary equipment sizing and life cycle costs of full scale treatment. An example of a commercially available system for arsenic removal using sulphide precipitation is presented. The benefit of this treatment method is discussed based on recently completed technical feasibility assessment including laboratory testing and preliminary engineering design. INTRODUCTION Selenium Due to the chemical similarity between selenium and sulfur, selenium substitutes sulfur in many minerals that can be found in a wide range of deposits including coal, base metal, precious metal, phosphate, and uranium. One of the main environmental challenges facing the industry in North America today is related to the removal of hexavalent selenium, e.g. selenate, to ultralow levels, typically between 1 to 10 ppb, from large flows of often cold water containing less than 1,000 ppb of selenium. Recent studies commissioned by the industry identified biological selenium reduction systems as the best available technology. Although the biological selenium reduction process is commercially proven in certain applications to remove selenium to ultralow discharge levels, the technology has been primarily applied to relatively low and constant flows of warm water produced by the Flue Gas Desulfurization (FGD) scrubbers in the power generation industry. The wide spread adoption of this treatment method by the mining industry is hindered by high capital and operating costs associated with treating large flows of cold water, lack of data and knowledge about the long term stability of solid residues produced by this treatment, and limited capacity of biological systems to respond to sudden changes in flow and/or mass load of contaminants. Furthermore, it has been reported that reaching discharge limits less than 3 ppb could be a challenge and that polishing treatment for the removal of BOD and phosphate maybe required to avoid the impact of the biological treatment which requires organics and nutrients, on aquatic environment downstream of treatment plants. Alternate treatment systems are being developed to overcome and/or completely avoid some of the challenges of biological systems. One such treatment system is BioteQ’s Selen-IX™ process which is purely physico-chemical treatment system."

Jan 1, 2015

By Jay A. Bowden

In April of 1990, Homestake Mining Company began a 5,100 m (16,700 ft.) exploration drift from the Homestake Mine in Lead, South Dakota. The drift starts from the mine's 6800 level, nearly 2,100 m below the surface, and extends north to further explore occurrences of gold discovered by surface drilling. Access to the North Drift for men and materials and for disposal of waste rock is limited to the Homestake Mine's #6 Winze, which serves as the major production shaft for the deep levels of the mine. This paper will discuss the successes and challenges encountered while managing a tunneling project 2,100 m below the surface and from an active mine.

Jan 1, 1993

By V. Matthews

"INTRODUCTION Typical grinding electrification requirements are defined by high power, constant torque and slow speed. Dual pinion mills also include a need for tight tolerances in torque between the two motors, to avoid overloading any single motor. Standard induction (asynchronous) motors have often been used but only in combination with mechanical gearboxes (reducers), required to reduce process speed to the correct level for mill pinions. The gearbox introduces added system complexity, capital cost, maintenance and energy cost due to mechanical losses. SYNCHRONOUS AND ASYNCHRONOUS MOTORS Elimination of the gearbox requires a motor designed to operate at a very low speed (rpm). Traditionally, mill motor requirements were best served by synchronous motors. The benefits of synchronous motors include- • Higher Efficiency (no conductor losses in rotor) • Very high power at low speed • Flexible Power factor (leading or lagging) • Constant speed (not load dependent) • More accurate speed control Synchronous motor cost is higher due to construction complexity, need for exciter and excitation panel, brushes, brush lifters. Figure 1 represents the equivalent circuit for a synchronous motor.Asynchronous motors, also known as squirrel cage induction motors, are singly excited, per Figure 2, the resulting equivalency circuit is less complex and only in need of a single voltage source.Commonly, a DC voltage supply is connected to the rotor (both physically and electrically) via brushes. The DC voltage enables the production of flux in a single direction. The brushes are connected to rings. The slip rings encircle the rotor but are insulated from the rotor. The slip rings are connected to a rotor winding known as a field winding. On large motors, brushless exciters are often used. A brushless exciter is a small AC generator whose field circuits are mounted on the stator and armature circuits are mounted on the rotor shaft. The exciter generator’s 3-phase output is rectified to DC by a 3-phase rectifier (mounted on the shaft) and fed into the main DC field circuit. It is possible to adjust the field current on the main machine by controlling the small DC field current of the exciter generator (located on the stator). [1] Brushless synchronous motors are often preferred over the traditional brush design but introduce additional complexity to motor construction in the form of additional windings and rectifiers comprising the excitation circuit. It stands to reason that because of the additional complexity, a synchronous motor will be higher in cost than an equally rated asynchronous induction machine."

Jan 1, 2015

By James W. Stewart, A. C. Colvine

Introduction Precambrian shield terrains the world over are experiencing an unprecedented level of concerted exploration for lode gold deposits. Reasons for this include: • The increase in the price of gold (following 40 years at $1.13/g or $35 per oz) has transformed targets that were once unattractive into viable exploration propositions. • The relatively suppressed market for other metals produced from shields (base metals, nickel, iron, and uranium) has further focused exploration attention on gold. • The preeminence of gold production from rocks of early Precambrian age, as shown in Fig. 1. • The relatively high grade of gold in these mines (averaging about 10 Wt or 0.29 oz per st) permits profitable extraction even under depressed gold prices. A number of these mines have been in continuous operation for more than 50 years. • The recent discovery of the major Hemlo deposit, in well exposed rocks adjacent to the Trans Canada Highway, has had a world-wide impact. This demonstrates that a major new deposit can be found even in an accessible, well exposed area of a shield; gold mineralization is susceptible to rational exploration; and new target types for gold exploration exist. This paper reviews exploration activity for gold in shield terrains worldwide (Fig. 2), excluding Early Proterozoic paleoplacers of the Witwatersrand type. Emphasis is on the Archean, which is traditionally the most productive part of the Precambrian shields. There is also an emphasis on the Canadian shield (Fig. 3) because of its vast areal extent and exceptionally broad range of mineralization styles. Geological Approach A basic problem exists in gold exploration when compared to exploration for base metal massive sulfides that predominated during the 1960s and 1970s. Gold concentrations cannot usually be detected by airborne geophysical instruments. The majority of massive sulfide deposits were detected using airborne electromagnetic detectors and magnetometers. A full 75% of Canadian gold discoveries can be credited to surface prospecting. The percentage is even higher in other countries. This observation allows for great optimism for two reasons: • Large areas of shield terrain are obscured by either surficial deposits (glacial tills, clays, and desert sands) or deep surface weathering. This makes them inaccessible to prospectors. Logic dictates that such obscured areas should have the same potential for gold concentration as has exposed bedrock. • The Hemlo style of mineralization, a roughly tabular ore body where gold is associated with disseminated sulfides, is different from the traditional prospecting target. The gold is hosted by discrete quartz veins. While it is true that limited discoveries were made at Hemlo more than 30 years ago, and this style of mineralization is present elsewhere, recent

Jan 12, 1984