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By P. G. Vikre

Several factors have caused less emphasis to be placed on geologic mapping in mineral exploration in the last 15 years. These include opportunities for "easy" discoveries of near surface gold and silver deposits in developed countries, and of base metal deposits as well in less developed countries, a decline of emphasis on geologic mapping in many universities, and a decline of useful mapping by government agencies in many areas. Geologic mapping is simply a way of recording geologic observations on volumes of rock larger than can be seen from one place. Since most geologic processes involve systems larger than this, mapping is also essential to understand the significance of observations made on smaller volumes of rock, such as thin sections and sample taken for chemical or isotopic analysis. To be useful, the observations recorded through geologic mapping are then interpreted to arrive at an understanding of the 3D geometry and geologic history of a volume of rock, which is used to direct mineral exploration, or any number of other purposes.

Jan 1, 1995

By A. W. Fahrenwald

[In studying coarse sand flotation3/ the question of the relation between fineness of grinding and mill capacity logically arose. Everyone familiar with present fine-grinding practice knows that the capacity of a ball mill or similar mill is determined, among other things, by the fineness of the finished product. Undoubtedly a great many mining companies must have a good deal of data directly bearing on this point, yet no quantitative relationship between ball-will capacity and fineness of finished product has been established. The experimental study presented here is an effort to establish this relationship in a semiquantitative way. The subject is a tremendously large one and grows in complexity as the study becomes more searching. In this work the power consumed by the mill in the various experiments was not determined end neither vas the steel consumption measured; mill capacity only was considered.]

Jan 1, 1930

A conventional paddle-type mixer and a gravity flow mixing device were evaluated for conditioning of phosphate ore with fatty acid and fuel oil, and for acid scrubbing prior to cationic flotation. Gravity flow mixing required less residence-time, but slightly higher reagent concentrations to achieve recovery levels similar to conventional conditioning. Grade was less sensitive to reagent concentration using the gravity flow mixer. For acid scrubbing, the gravity flow mixer proved equally effective. In this paper, the effect of time, pulp density, reagent concentration, and emulsification on conditioning and acid scrubbing efficiency of the two devices will be discussed.

Jan 1, 1987

By James M. Peay

This paper discusses the recently completed organizational development research project, which was addressed to the underground mining industry. The three specific purposes of the project were as follows: (a) to determine whether Organizational Development approaches are feasible in the mining industry, (b) to provide a demonstration that Organizational Development methods can successfully contribute to the safety of underground mines, and (c) to compare the efficacy of classical Organizational Development methods, which are highly trainer- intensive, with trainer-nonintensive management development approaches. The term "Organizational Development" (OD) is here broadly defined as a management intervention for the purpose of assisting an organization with the solution of problems, which are seen by the organization as important. More specifically, we can define OD as a planned effort to improve the effectiveness of an organization through (a) team building and problem solving, which concentrates on the issues of immediate concern to the organization, and (b) efforts to improve organizational communication at all levels of the organization.

Jan 1, 1983

By G. R. Hopkins

According to reports received by the Bureau of Mines, Department of Commerce, as of January 1, 1929 there were 413 completed refineries in the United States, with a total daily crude-oil capacity of 3,509,540 barrels. In addition, 14 refineries, with a potential capacity of 99,000 barrels, were being constructed. Of the completed refineries, 341, with a capacity of 3,325,890 barrels, or 95 per cent of the total capacity, were in operation; and 72, with a capacity of 183,650 barrels, or 5 per cent of the total, were shut down. The improved condition of the refining industry in 1928 was indicated in several ways; namely, in an increase in the total capacity of the completed plants, in the opening up of a few plants which were shut down during 1927, in a decrease in the number of plants dismantled, and in an increase in the number of plants under construction. The majority of the refiners have followed a steady expansion program commensurate in most cases with the increase in demand for petroleum products. Obsolete equipment has been dismantled and modern equipment has been installed, with the net result that the total capacity of the completed refineries in the United States has shown a steady increase since January 1, 1918, the date of the first Bureau of Mines survey. Between January 1, 1928, and January 1, 1929, the number of completed plants fell from 423 to 413, but their total capacity increase 259,160 barrels, or 8 per cent. This compares with an increase in runs to stills of domestic and foreign crude petroleum of 10 per cent, and of domestic crude alone of 7 per cent.

Jan 1, 1929

By F. S. Knoll

Electrostatic separation is one of the most misunderstood physical processes used to beneficiate minerals. Nonetheless, millions of tons of titanium ores, iron ores and other minerals are processed every year economically, efficiently and safely. Over the past ten years major advances in electrostatic separation and its application have occurred. New processes include dewatering clay slurries, separating halite and sylvite, and shape separation of vermiculite and gangue minerals. Electrostatic separation techniques are based on one of two methods, electrophoresis or dieleccrophoresis -- processes involving charged and uncharged particles respectively. In some cases, the combination of these two techniques has proven quite useful. The purpose of this paper is to provide a basic understanding of the physical processes collectively called "electro- static separation" in order to enhance one's ability to define and consider new possibilities in mineral processing and other fields.

Jan 1, 1984

The properties required for a com-pound to form useful thermoelectric materials are described. Uranium compounds which might have these properties are reviewed. Several of these compounds have been prepared and fabricated into compacts. The apparatus used for hot pressing, and for the measurement of thermoelectric power, electrical conductivity and thermal conductivity, is described. Detailed attention has been given to the properties of the nitrides. Preliminary studies on a number of other uranium compounds are reported. The figures of merit of the best materials so far examined are one-tenth of those necessary for a useful thermo-electric material. THE efficiency of thermoelectric materials for power generation and cooling is determined by their figure of merit, Z = a2 a/K, where a, a and K are thermoelectric power, electrical conductivity and thermal conductivity, respectively. It is well known that the largest values of Z are achieved with semiconductors (1). High mobility of charge carriers is necessary for simultaneously high thermoelectric power and electrical conductivity.The properties required for a com-pound to form useful thermoelectric materials are described. Uranium compounds which might have these properties are reviewed. Several of these compounds have been prepared and fabricated into compacts. The apparatus used for hot pressing, and for the measurement of thermoelectric power, electrical conductivity and thermal conductivity, is described. Detailed attention has been given to the properties of the nitrides. Preliminary studies on a number of other uranium compounds are reported. The figures of merit of the best materials so far examined are one-tenth of those necessary for a useful thermo-electric material. THE efficiency of thermoelectric materials for power generation and cooling is determined by their figure of merit, Z = a2 a/K, where a, a and K are thermoelectric power, electrical conductivity and thermal conductivity, respectively. It is well known that the largest values of Z are achieved with semiconductors (1). High mobility of charge carriers is necessary for simultaneously high thermoelectric power and electrical conductivity.

Jan 1, 1963

By T. J. Lutz, L. Yan, J. R. Srednicki, J. A. Yonkey, G. T. Homce

"Federal regulations require the installation of refuge alternatives (RAs) in underground coal mines. Of the in-use RAs, over 95% are mobile RAs with the remainder being built-in-place (BIP) RAs. Heat/humidity buildup has been one of the major concerns with mobile RAs. For BIP RAs, however, there is a lack of in-mine heat/humidity test data to determine the extent of heat and humidity buildup. To quantify heat/humidity buildup in BIP RAs, the National Institute for Occupational Safety and Health (NIOSH) performed a series of heat/humidity tests on a 60-person BIP RA with and without a borehole air supply. At various times during the year, tests were performed with cooled, heated, or unconditioned borehole air to examine how various outdoor temperatures may affect the thermal conditions inside a BIP RA. The results show that the air supplied to a BIP RA may require heating and cooling, depending on the outside air temperatures and the temperature of the mine. For example, during tests with an external ambient temperature above 70°F and a humidity that reached 90 %RH, providing 55°F dew point air was able to keep the internal apparent temperature below the mandated 95°F. Results for each test case are presented. INTRODUCTION The Mine Safety and Health Administration (MSHA) has required the installation of refuge alternatives (RAs) in underground coal mines since 2008 [1]. MSHA requires that RAs provide an environment with breathable air for entrapped miners for a 96-hour period. Heat buildup inside an occupied RA is a serious concern. Without a means to dissipate the heat and humidity generated by the occupants and the carbon dioxide scrubbing system, the temperature and humidity inside RAs could lead to severe discomfort or heat stress depending on the mine ambient temperature before and during occupation of the RA. In its 2006 report, the West Virginia Mine Safety Technology Task Force recommended an apparent temperature limit of 95°F for RAs [2]. In 30 CFR 7.504, MSHA specifies a maximum apparent temperature of 95°F inside an occupied RA [3]. The apparent temperature is calculated using both air temperature and relative humidity [4]. To determine if their RAs meet the apparent temperature limit, RA manufacturers have been performing 96-hour-long heat and humidity tests in laboratories. During these tests, a heat input of 117 W (400 BTU/hr) per person is used to represent the metabolic heat of a single miner [2]. The heat generated by the RA’s carbon dioxide system is also accounted for in testing. To account for this heat, 50 W (170 BTU/hr) of heat per miner is used for a lithium hydroxide scrubbing system, or 30 W (100 BTU/hr) of heat per miner is used for a soda lime scrubbing system [5]. In these tests, air velocities around the RA are minimized to represent the worst-case scenario of an interruption in mine ventilation that might occur in a mine disaster."

Jan 1, 2017

By G. R. Elliott

Foreword The office of the Supervisory Mining Engineer, a branch of the l. Federal Government, is financially interested in no oil company and has no stock to sell. This office, however, is deeply interested in the proper and efficient development of Canada's natural resources. The people of Canada are interested in the petroleum development in Turner Valley for two principal reasons: As represented by the Department of the Interior, they are the largest owners of petroleum and natural-gas rights in the field; As a nation, they are vitally interested in the development of petroleum and natural gas as a national asset, and therefore, also, in all productive property, no matter who directly controls the leases. As has been stated by Mr. Charles C. Ross, Supervisory Mining Engineer, "The Department, being responsible for the administration of these public resources, necessarily requires regulations to protect them from abuse by lessees. Our portion of this responsibility is to record a complete history of all drilling operations and to see that proper drilling methods are adopted to prevent damage and wanton waste of the valuable natural resources under discussion." Not only does our position necessitate an impartial and a judicial viewpoint, but, being day by day in touch with all operations in the western provinces, we are uniquely situated to comprehend both individual and general problems.

Jan 1, 1930

By H. E. Dresch

This report summarizes the work accomplished under Bureau of Mines contract H0188068. The contract required design and construction of a high voltage (7.5 KV) explosion proof cable connector for use on underground coal mine drag cables. A connector was constructed with elastomeric phase insulators that provide insulation shielding throughout the connector length. Connector housing was made of flame resist-ant cast poly urethane with no exposed metal components. Electrical and mechanical testing of the completed coupler resulted in satisfactorily meeting most of the design testing requirements.

Jan 1, 1981

By F. J. Gallagher

Some serious fires have occurred in bituminous-coal mines because of short circuits on direct-current power systems that do not have adequate circuit-breaker protection. The writer's observation of circuit-breaker installations in numerous coal mines leads to the conclusion that many persons am not properly informed as to the true functions, limitations, and operation of circuit breakers. Faulty protection results in fire hazards that endanger lives and property. Proper circuit-breaker protection would greatly minimize or, in many instances, eliminate the hazards; moreover, many operating advantages of proper application of modern circuit breakers would be gained. The purpose of this circular is to show why fire hazards exist in many mines despite the use of circuit breakers and how, the hazards may be overcome. A method is given for determining whether additional circuit-breaker, protection is required for a specific 250/275-volt direct-current distribution system, and, if so, the approximate locations and capacities of the required supplemental breakers.

Jan 1, 1951

By D. K. Panda

The behavior of single drops with gas evolution at the interface is of interest because this is one of the important reactions that occur in oxygen steelmaking vessels, where a large amount of iron-carbon drops are dispersed in an oxidizing slag. The carbon dissolved in these drops, reacts with the slag to form CO, which is evolved as a gaseous phase. A room- temperature model was used to study the nature of this type of reaction including the effect of various factors such as viscosity and the presence of surface active impurities. Experiments were done for reacting drops over a wide size range to observe various regimes of behavior. Large single drops were levitated in a counter current flow to produce a sufficiently long residence time to allow the study of the various stages in the reaction. The emphasis of this work was to obtain photographic evidence of a high quality to describe all possible modes of behavior, and so a lot of effort was given to developing and perfecting experimental techniques.

Jan 1, 1994

By G J. Harbort, K Lam, C Sola

The relationship between the geology of porphyry copper deposits and their processing performance is an area of interest. Being able to predict comminution properties of the ore from physical characteristics and geological descriptions would allow an increase in the precision of capital cost estimates, operating cost estimates and throughput rates. This geometallurgical approach would reduce the requirements for expensive comminution tests.As the comminution circuit is the highest capital cost item in the plant and a possible throughput bottleneck, understanding the variability in hardness within the orebody is critical. A geometallurgical model allows calculation of ore hardness values in mining blocks from ore characterisation data. This model subsequently uses a combination of simulation and power-based approaches to relate ore hardness and flotation feed size to grinding circuit throughput.This paper reviews the geometallurgical models developed for seven porphyry copper deposits and discusses the strengths and shortfalls of the methodology and similarities and differences between the different deposits.CITATION:Harbort, G J, Lam, K and Sola, C, 2013. The use of geometallurgy to estimate comminution parameters within porphyry copper deposits, in Proceedings The Second AusIMM International Geometallurgy Conference (GeoMet) 2013 , pp 217-230 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 29, 2013

By E C. Holloway

"The financial valuation of mining assets has a number of fundamental differences to the valuation of many other asset groupings. One such difference is that typically, the greater proportion of both the cost and revenue sides of the cash flow are inherently governed by systemic market forces.As a result, the range of outcomes for the valuation of each mining asset is more unpredictable, with higher levels of risk and uncertainty. In contrast, the management function of many other non-mining businesses or industry groups can control at least a portion of the cash flow by maintaining the margin or controlling the sales price. The management teams of mining businesses and operations typically have limited options, and are thus price-takers for both costs and revenues. As mining is an inherently cyclical industry, large, long-life operations can exist through several price cycles, making valuation both subjective and challenging.The outcomes of both static- and stochastic-based valuations, as well as the internal probabilities of the associated cash flow statements, are significantly impacted when the correlations between the appropriate parameters are quantified, modelled and incorporated into the valuation framework. The appropriate parameters for correlation modelling primarily include those that are governed by systemic market forces. Applying this process results in a different risk profile for the asset by allowing the risks resulting from systemic market movements to be more accurately quantified and then objectively minimised. This process also reduces the level of residual uncertainty in the valuation outcome.This paper presents a valuation methodology to pragmatically incorporate this level of valuation sophistication and statistically quantify the associated increase in the level of confidence of the valuation outcomes reported.CITATION:Holloway, E C, 2016. Correlated valuation methodology, in Proceedings Project Evaluation 2016, pp 181–200 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 8, 2016

By A. K. Gangopadhyay

This paper discusses the effect of grinding media composition, mineral type and slurry environment on the wear rate of various grinding media (balls). Sufficient wear data have been obtained and correlated with the modes of wear determined from examination of the ball surfaces using scanning electron microscopy. Five modes of wear have been identified to be operative under certain slurry conditions for the various ball compositions studied.

Jan 1, 1984

By Michael K. Watkeys, Charlesworth. E. GUY, Jacobus E. Potgieter, Anhaeusser. Carl R., Roger L. Gibson, Alexander F. M. Kisters

Abstract - Intrusive features of cupriferous noritoids from the deeply eroded Proterozoic granite-gneiss terrane of the Okiep Copper District in South Africa illustrate the emplacement of basic magmas into a mid- to lower-crustal environment. The small, easterly trending intermediate to basic intrusions of the so-called Koperberg Suite display a wide variety of geometries, occurrence and emplacement modes, including dike-, sill- and plug-like bodies. Coeval granulite-facies metamorphism, partial melting and ductile deformation of country rock gneisses during intrusion of the basic magmas led to emplacement and dilation processes of the intrusions which differ significantly from those described for dikes and sills at shallow crustal levels. Regional tectonic stresses are largely negligible due to very low differential stress (?1 - ?3) during deformation and intrusion, which permits emplacement at high angles to the principal compressive stress and which follows favorably inclined structural anisotropies. Dilation of the basic intrusions is largely determined by compositional differences of host rocks and occurs by thermal erosion, i.e., assimilation of wall rock gneisses. Low length-to-width ratios of basic to ultrabasic dikes and predominantly diaper -like outlines of mesocratic bodies are indicative of low viscosity contrasts between the mafic magmas and high-grade metamorphic host-rock gneisses. Buoyancy-controlled ascent of the basic to intermediate intrusions is expressed by a broad compositional zoning of basic bodies with respect to the granite-gneiss stratigraphy. Various intrusion modes within the stratigraphic column of the granite-gneiss sequence reflect a lithological and structural stratification of the seemingly homogeneous granite-gneiss terrane.

Jan 1, 1994

By J. H. Elledge

Hydraulic Transportation of Phosphate Ore from, a 40,000 Cubic Yard per Day Strip Mine IMC is transporting 1500 yards per hour of phosphate ore in a water slurry a distance of approximately five miles from a strip mine to a flotation beneficiation plant at their Noralyn Operation. in Barrow, Florida. This ore, which consists of approximately 1/4 phosphate, 1/2 silica sand, and 1/4 clay slimes, is being pumped through a 20 inch O. D. pipeline using seven 20 and 18 inch GIW metal pumps direct connected to electric, motors. This paper details some of the problems involved and the specific methods used to accomplish this bulk material handling requirement.

Jan 1, 1966

By William E. Horst

Ore grindability data based on various techniques to measure comminution characteristics are used to evaluate the crushing and grinding efficiency in mineral processing operations. The importance of achieving improved comminution efficiency, in terms of energy consumption, has been emphasized by recent increases in the cost of electricity. From a theoretical standpoint, the objective of a grinding operation might be expressed as maximizing the production rate at a given grind size while minimizing the energy consumption per ton of material ground. To achieve this objective in an industrial operation presents a challenge especially in view of changes in the raw material which are normally encountered. Various procedures1-5 used to determine energy-size parameters and grindability measurements have been reported. The proposed relationships between particle size and energy consumed have much in common between many of the techniques for measuring grindability. Probably the most widely used parameter to measure ore grindability in recent years is the Bond work index6, Wi, which is defined as the kw-hr per ton required to break from infinite size to a product size of 80 percent passing 100 microns. If the breakage characteristics of a material remain constant over all size ranges, then the calculated work index would be expected to remain-constant since it expresses the resistance of material to breakage. However for most naturally occurring raw materials differences exist in the breakage characteristics depending on particle size, which can result in variations in the work index depending on grind size. Consequently work index values are generally obtained for some specified grind size which typifies the comminution operation being designed or evaluated.

Jan 1, 1975

By M. Sunkpal, K. C. Kocsis

"An underground environment with high air temperature and humidity conditions generated from various heat and moisture sources can significantly affect the thermoregulation processes of the human body. This can lead to a series of heat-related illnesses such as heat exhaustion, heat cramps and heat stroke. The majority of the metabolic energy of a mine worker results in the production of heat. If the human body is to maintain thermal equilibrium, then this metabolic heat must be transferred to the ambient surroundings at the same rate. The heat loss from the human body occurs through a combination of heat transfer processes, such as respiratory heat exchange, convection, radiation and evaporation. If the heat loss from the human body to the ambient surroundings is less than the metabolic heat produced, the excess will be accumulated within the human body, which will result in a rise in the core and skin temperatures. This can ultimately lead to a heat-related illness or a combination of heat-related illnesses. This paper aims to discuss major heat-related issues and provide an overview of various mine ventilation and cooling systems, which can be employed to overcome high levels of heat and humidity in underground mines. In this paper, the effects of heat exposure on the health, safety and productivity of the mine workers are also highlighted. IntroductionMining in the United States remains one of the most hazardous industries, despite significant reductions in fatal injuries over the last century (Coleman and Kerkering, 2007; Saleh and Cummings 2011; Jacklitsch, Musolin and Kim, 2016). Occupational health hazards within the mining industry include hazards that are physical, such as traumatic injury or hearing loss; chemical, such as silica or diesel particulate matter; biological; ergonomic; and psychological (Donoghue, 2004; Saleh and Cummings, 2011). The effects of some of these hazards can be diagnosed immediately, while many, like black-lung and silicosis, will have long-term effects on the health, safety and life quality of mine workers (Donoghue, 2004; National Institute for Occupational Safety and Health, NIOSH, 2000). Among these hazards, exposure to heat and humidity can significantly affect the safety, health and productivity of mine workers, particularly in deep and hot underground mines (Roghanchi, Sunkpal and Kocsis, 2015). Short-term acute heat exposures can cause a rise in the core temperature of the human body, which can result in a heat-related illness or combination of heat-related illnesses. Adverse long-term chronic heat exposure can generate serious occupational heat-related illnesses, such as cardiovascular diseases, mental health problems and chronic kidney diseases. High core body temperatures coupled with dehydration can generate negative behavioral effects such as physical fatigue, irritability, lethargy, impaired judgment, loss of dexterity and loss of concentration (Xiang et al., 2014)"

Jan 9, 2017

By Robert D. Schmidt

The Cyprus Casa Grande Corporation has provided Bureau of Mines researchers with an opportunity to investigate the hydrology of leaching an in place copper ore deposit. Hydrologic investigations of underground in situ copper leaching are being jointly conducted under a cooperative agreement. The hydrologic concerns of leaching operations at the Casa Grande mine focus on maintaining adequate solution injection and recovery rates, and on distributing the injected leach solution effectively within the ore deposit. Hydrologic considerations underlying these concerns relate to the permeability of the oxide ore zone during leaching, the unsaturated condition of the deposit prior to leaching, and the constraints imposed on in situ hydrologic design by the underground mine setting. The investigation involves monitoring of flow and pressure conditions in 58 injection and recovery wells, estimating permeability conditions using a hydrologic model, and on-site testing of hydrodilation and airlift pumping. Transient, fracture-controlled permeability is determined to be the dominant hydrologic consideration. A statistical modeling procedure has been developed for estimating changes in permeability during leaching. Flexibility in well design and operation is essential for accommodating the changes in fracture permeability that occur during leaching.

Jan 1, 1990