Search Documents

By J. M. West

Increased leisure time and increased interest in the out-of-doors is leading more and more families to experiment with placer mining of gold, and some- times even to going on into small-scale production. This Bureau of Mines report supplies basic information un areas of occurrence, equipment needed, prospecting, sampling, mining, and regulations concerning the possession and sale of gold. Selected references are given for further study.

Jan 1, 1971

By Dean H. Ambrose

This paper presents the results of a study using computer human modeling to examine machine appendage speed. The objective was to determine the impact of roof bolter machine appendage speed on the likelihood of the operator coming in contact with. A contact means two or more objects intersecting or touching each other, e.g., appendage makes contact with the operator?s hand, arm, head or leg. Incident investigation reports do not usually contain enough information to aid in studying this problem and laboratory experiments with human subjects are also not feasible because of safety and ethical issues. As an alternative, researchers developed a computer model approach as the primary means to gather data. By simulating an operator?s random behavior and machine?s appendage velocity, researchers can study potential hazards of tasks where it is not possible to perform experiments with human subjects. Analysis information is helpful to the mining industry in terms of making recommendations that reduce the likelihood that roof-bolter operators experience injury due to contact with a moving boom. Data analysis of roof bolter simulations show that the virtual-operator?s response time has little effect on the number of contacts experienced. Based on frequency and cross-tabulation, regardless of other variables, contact incidents were always greater when the boom was moving up, were always greater on the palm, and were always greater for the boom part of the machine. Also, regardless of boom speed, the 25th-percentile-sized operators experienced more contacts than did other operator sizes. Furthermore, regardless of boom speed, the 152-cm mine seam experienced more contacts than did other seam heights tested. Results of a survival analytic approach suggest that controlling the boom speed is the most important factor in determining the risk of an operator making contact. Based on the data collected, boom speed greater than 41 cm/s results in a substantial increase in risk to the roof bolter operator and should probably be avoided. At speeds less than or equal to 25 cm/s are associated with a more modest relative risk, which represents an acceptable level of risk. Also, at speeds between 25 and 41 cm/s, there could be a particular boom speed in this range at which a significant inflection point in the relative risk estimates occurs. Based on the results, this issue needs to be addressed by future research.

Jan 1, 2003

By L. A. Morely

The overall objective of the subject contract was to investigate the application, economic, and safety considerations of electrical-shock prevention techniques applied to surface and underground mines. Volume I of the four-volume final report starts by summarizing all research performed, and synopses of the three other report volumes are included. The balance of this volume concerns one major task of the contract, the protection of maintenance personnel. After specifying the scope of work for the task, electrical is defined, and needed ground-fault relay characteristics to prevent ventricular fibrillation are established. This is followed by an analysis of alternating-current systems, a comparison of these systems with respect to body currents, and the advantages and disadvantages of the various ground-fault protection techniques. An analysis of direct-current systems for off-track vehicles is then covered. These analyses form the basis for the research recommendations which along with suggestions for future research, conclude the report volume.

Jan 1, 1982

By I. Gaballah

Cadmium is toxic to plant, animals and humans. The council directive of the European Communities No 8315 13lEEC has fixed an upper limit of 200 ppb for the release of cadmium in industrial effluents. The conventional method of neutralization/prccipitation ( NIP ) is inefficient to reach this limit. The objective of this study is to test the efficiency of the trees modified bark to remove cadmium cations from industrial effluents after the conventional treatment by NIP. Laboratory scale tests with synthetic solutions show that the cadmium removal depends upon pH and initial concentration. About 99.9 %, 99 % and 96 % of the metal are removed from synthetic solutions containing 10, 100 and 1000 ppm respectively. Pilot plant trials ( 1 m3 ) with an industrial effluent bearing about 500 ppb of cadmium lead to the almost complete elimination of the cadmium ( final concentration is lower than the analytical detection limits < 20 ppb ).

Jan 1, 1994

The purpose of the contract was to develop an improved coal mine dust sampler whose electrical-to-mechanical energy conversion efficiency would be superior to that of the presently available equipment. The electrical to (pressure) X (volume) conversion efficiency directly affects the size and weight of the air samplers. At least half of the mass of present equipment is composed of the rechargeable batteries. Any increase in efficiency will allow this mass to be reduced or the flow rote to be increased.

Jan 1, 1974

By Richard C. Rice

Laboratory and field data for wire ropes typical of constructions used in underground mine hoisting were obtained, screened, encoded and analyzed statistically. The statistical analysis of data for hoist ropes retired from service showed that rope remaining strength (or, conversely, strength loss) can be predicted with good accuracy if several nondestructive measures of rope damage are assessed. Found to be most important was the outer-wire corrosion rating, the electromagnetic (EM) nondestructive-inspection technique used for predicting strength loss, and the rope diameter reduction. Signs of rope deterioration such as broken wires or damage were also important indicators of strength loss. Based on the results of this investigation, a number of recommendations are presented that promise to yield better rope inspection and retirement criteria which will in turn lead to improved safety and efficiency in underground mine-hoist systems.

Jan 1, 1983

By S. M. Shelton

Tests employing various ore-dressing methods were made on a manganese wad ore from the W. A. Chinn property in the Batesville-Cushman district of Arkansas in an effort to develop a practicable procedure for the production of ferromanganese-grade concentrates. The ore body occurs as a bed approximately 7 feet thick in the residual clay of the Ferndale limestone formation5/. The crude wad ores are soft aggregates of various oxides of manganese, which are loosely bonded together. Hard lumps of high-grade ore are disseminated throughout the wad. Hausmannite, pyrolusite, and psilomelane are the principal minerals. Some clay is present, but most of the gangue consists of leached fragments of the original siliceous and calcareous rocks in which the manganese occurred. In addition, hydrated oxides of iron, which axe present, also must be considered as gangue. Definite phosphate minerals have not been identified.

Jan 1, 1942

By J. C. Boswell, J. D. Crawford

IN addition to its base-metal and coal mining operations, the United States Smelting Refining and Mining Company has, for the past quarter century, been one of the few large American mining companies interested in dredging. Its activities in this field are confined to gold, and to Alaska, but it is the largest operator in that territory, with twelve huge dredges available to work during the summer on the frozen ancient beach sands at Nome and the gravels of Fairbanks. These operations will be described separately.

Jan 1, 1948

By C. Kasatuka

Globalization creates investment opportunities for enterprises around the world. Attracting foreign investment has been a key challenge for economic growth in developing countries. Corruption, political instability, armed conflict, and other internal problems affect foreign direct investment (FDI) inflows negatively. A framework of criteria provides a basis for comparing non-commercial risk (NCR) among twenty-three mineral economies. Countries competing for foreign direct investment inflows are ranked from least to most risky. This study compares Inward FDI Performance Index (IND) with NCR ratings in developing countries and shows that risk is increasingly mitigated by means of appropriately structured insurance. Given the option for countries with similar mineral potential, investors will generally invest in the country that offers lower non-commercial risk. Keywords: foreign direct investment, non-commercial risk, developing countries.

Jan 1, 2006

By E. V. Lilford

Valuators of mineral properties are faced with a range of valuation methodologies, the most important of which are grouped under the headings of the market approach, the cost approach and the income approach. The way in which value is defined and the detail of the different valuation methodologies is examined here. This paper aims at documenting the variety of valuation procedures and applying each method to a variety of gold projects and comparing the outcomes. Any decision to apply a valuation technique will depend principally on the stage to which the project has been developed. The valuation approach to a greenfield project will be substantially different from that applied to a well-drilled, extensively explored mineral property. Furthermore, a valuation exercise may produce different outcomes for the same gold project depending on which method is applied. In order to investigate the variability in valuation methods and to explore the outcomes of different approaches, a series of five gold projects was analysed. The projects differ in regard to levels of capital application, infrastructural setting, depth below surface, in situ grade, and the stage of development, and were valued using the different methods. The most critical aspect of any valuation is the capacity of the valuer to identify the salient issues and ensure that they are incorporated into the valuation. The danger of simply applying ?black box? solutions to valuation problems without a full understanding of the parameters and the areas of uncertainty is emphasized. The importance of the valuator?s experience, insights into best practice and the ability to recognize and submit to the requirements of compliance within the minerals industry is among the most important characteristics of a valuer.

Jan 1, 2005

Breaks in coal slurry impoundments can threaten the lives and health of area residents, destroy homes and businesses and contaminate water supplies. This dangerous potential looms over coalmining regions in West Virginia and throughout Appalachia. The Coal Impoundment Project was begun in June 2003 to provide an inventory and mapping of active and abandoned impoundments in West Virginia. The project also provides the public with specific information about the impoundments in their communities. It is dedicated to alerting residents of danger and evacuation plans, reducing risk to residents and finding alternatives to impoundments. Since its first year, more than 100 impoundment sites have been added to the project’s Website.

Jan 1, 2005

By L. Li

The performance of microemulsified diesel and conventional diesel collectors in coal flotation was compared by flotation indicators, including combustible recovery, ash content of the clean coal, and the flotation index. An efficient separation with lower dosage was obtained using the microemulsified diesel collector. Under optimum separation conditions, the microemulsion consumption was 100 g/t less compared with diesel. The saving in diesel consumption using the microemulsion reached about 70%, disregarding the consumption of the surfactant and cosurfactant. Frothing tests showed that the frother dosage was decreased by using the microemulsion collector, because of the surfactant and cosurfactant added during preparation. The microemulsified diesel collector is superior to the conventional diesel collector in terms of diesel consumption and separation efficiency, but the selectivity requires further improvement. Keywords froth flotation, microemulsified collector, coal.

Nov 1, 2013

By Ivan E. Goodner, Charles H. Fulton

THE subject of the constitution of copper-iron mattes has received considerable attention in recent years by Keller,1 Bolles,2 Hofman,3 and Gibb and Philp.4 Still more recently Friedrich, Röntgen, Wiedmann, Heyn and Bauer, and Leroux have published, in some instances, elaborate researches on the various systems of the sulphides, and the sulphides and their respective metals, which enter into the constitution of mattes, and have added very greatly to the knowledge of the subject. The work of Friedrich has been especially fruitful. But to date no effort has been made to correlate the data obtained in the latter researches and apply then to the study of the product called " matte," which is made in such large quantities by copper and lead-smelters. In this paper we propose to determine, by metallographic and chemical means, the constitution of copper-iron and copper-lead mattes in the light of the recent data above mentioned. We do not discuss copper-nickel mattes or speisses (artificial arsenides). The paper is divided into three sections I. A review and discussion of the various binary systems of the metallic, sulphides, and the binary systems of various metals and their respective sulphides entering into the constitution of mattes; also a discussion of the physical and chemical properties of these sulphides. II. A description of the results obtained from the chemical and metallographic examinations of the samples of copper-iron and copper-lead-iron matte obtained from various plants.

Nov 1, 1908

By A. J. Farstad

Recent advances in microcomputer technology have opened the way for systems which can track the location of underground mining personnel from the surface. A computerized system has been designed which is capable of not only tracking the location of the miner but also of monitoring underground parameters, communicating between work stations and sounding alarms when underground conditions are judged to be unsafe. For the system described herein, the locations of the underground personnel are detected by a network of underground terminals which routinely emit RF pulses to interrogate miniature transponders worn by the miners. Each transponder is uniquely programmed to delay its response in such a way that the RF terminal can identify the individual transponders by the time slots in which the responding pulses are received. The underground terminals are then interrogated by the host computer on the surface which keeps a running account on underground mine conditions and personnel. The underground portion of the system is designed to operate even during mine emergencies, deriving its power from rechargeable battery supplies which are float charged during normal operation. Nine mines were visited on this program and the industry reaction to the system was generally favorable. By slanting the system design for daily use in the mine, the chance of its acceptance by the industry is enhanced. Furthermore its likelihood of being operational in the event of an emergency is significantly increased.

Jan 1, 1981

By Anthony T. Iannacchione

The Roof Fall Risk Index (RFRI) is a new method introduced by the National Institute for Occupational Safety and Health (NIOSH) to assist the underground stone mine operator in 1) assessing defects the mine strata and 2) rating the relative roof fall risk these defects pose. The RFRI utilizes observational techniques to identify defects in the roof strata caused by local geologic, stress, and mining conditions. Assessment values for ten defined defect categories provides the foundation for estimating a range of risk conditions between 0 and 100 that define the potential for a roof fall. This paper examines how the defect information is collected using two field verification sites and proposes methods to analyze the RFRI data. These examples provide information on how well the method replicates observed conditions and how it might be applied in practice.

Jan 1, 2006

By R. V. Ramani

This volume is the fourth of a four-volume final report on research carried out under a contract from the U.S. Bureau of Mines on the development of a computer simulation model for surface mine reclamation planning. The other volumes are titled as follows: Volume I: Ore Reserve Estimation, Volume II: Dragline Model, and Volume III: Mine Coordinate Generator System. The Open Pit Materials Handling Simulator (OPMHS) was first developed" in 1971 and modified and updated in 1975. The present work is an update of the 1975 version and provides a direct link between the geology and reserves system and the various activities of the mining equipment in a mining system. Also, the modeling techniques in OPMHS/2 have incorporated a flexible method for describing various equipment (shovels, trucks, belts, trains, etc.), locations, their sequence of operations, place changes, and their interactions. These features allow for studying mining equipment selection, mining method analysis and reclamation planning. This report describes the Open Pit Materials Handling Simulator Version 2 (OPMHS/2). The report details the program features, operation, and application. Through an extensive set of appendices, the data input sequence, input variable definitions, sample data listing and program output are presented in detail.

Jan 1, 1985

By J. L. Bowlby

The heats of combustion of fuels are determined in the laboratory by means of a calorimeter, usually of the oxygen bomb type. A known weight of the fuel is burned in an atmosphere of oxygen under approximately 400 pounds pressure in a heavy metal container-the bomb- and the heat evolved is imparted to a definite quantity of water. From the rise in temperature, measured by means of a Beckmann thermometer, and other data incidental to the determination, the heat value of the sample can be calculated. On paper, the method appears simple indeed, but in practice the determination of the heat of combustion is one of the most difficult of the various coal analyses. This h as led to considerable investigational work in order to obtain formula: whereby calorific values of solid fuels could be calculated from proximate analysis data al one. The proximate analysis of a fuel consists of the determination of moisture, ash, and volatile matter, with fixed carbon by difference. Sulphur determinations properly belong to the ultimate analysis, but in this section of the country, where the sulphur content of the coal is comparatively high, a request for the proximate analysis of a fuel implies the determination of the sulphur as well.

Jan 1, 1929

By J. Bongardt

Ecologically acceptable techniques are described for the handling of waste materials from the fabrication industry. New production methods and the recycling of sludges from grinding and other waste materials are suggested.

Jan 1, 1997

By P. T. Slatter

The efficient and accurate design of pipe and pumping plant for non-Newtonian mineral slurries remains a problem. The objective of this paper is to present the development of the Balanced Beam Tube Viscometer (BBTV), an instrument which could facilitate more accurate design for these slurries. The background of rotational and tube viscometry is reviewed and the fundamental principles and inherent advantages of the BBTV are given. The design, data acquisition and processing techniques are introduced and results showing the reliability of the new instrument are presented and discussed. It is concluded that the BBTV is a reliable and versatile instrument for both routine analyses and research work, and has the potential to provide data for the refinement of the design procedure for mineral slurry pipe and plant design.

Jan 1, 1998

By J. E. Campbell, A. W. Wesner, M. Pobereskin

This paper summarizes the results of an investigation sponsored by The Coates Steel Products Company. The objective was to determine the relative effects of certain chemical and physical properties on the wear resistance of grinding balls when grinding cement. In making this study, a number of types of balls were used in both dry and wet grinding in commercial ball mills. The radioactive-tracer technique was used in separating the test balls from the rest of the mill charge and in sorting the different types of halls that were all tested at the same time for each of the grinding operations. PROCESSING OF GRINDING BALLS In order to determine whether the properties of grinding balls, namely, composition, microstructure and hardness, can be related to the rate of wear, the halls used in this study were selected to represent various combinations of these properties. It was recognized that the mechanism of wear was not the same in the wet mill as in the dry mill. Therefore, the types of balls tested in each of the two environments were not necessarily the same. However, all of the types of balls evaluated in the dry mill were tested simultaneously for one time period, while those evaluated in the wet mill were tested simultaneously for three different time periods. All of the test balls were separated from the charge when the mill was dumped. All of the balls were of 0.940-inch diameter when charged, and all but the regular production balls were finish ground to this size to eliminate the decarburized surface layers. The steels and processing methods used, as well as the micro-structures and hardness levels of the balls, are described as follows: Regular production forged SAE 1095 steel balls were used in both the wet and dry mills. They were forged to a nominal diameter of 0.940 inch and quenched in oil from the forging temperature. Each retained a partially decarburized surface layer from the forging bar stock; the maximum depth of this layer was about 0.030 inch and the decarburization was negligible where the ball was sheared from the bar. The hardness at the surface was 40 to 46 Rock-well C in the partially decarburized area and 57 to 62 Rockwell C in the areas not decarburized. The hardened zone extended to a depth of about one-third of the radius. Below the decarburized layer, the hardened zone consisted primarily of hard as-quenched martensite with varying amounts of retained austenite. This structure changed to fine pearlite at a depth of about one-third of the radius. In order to eliminate the effect of the decarburized layer, a set of production balls of SAE 1095 steel was forged to about a 1-inch diameter, quenched in oil from the forging temperature, and ground on ball-bearing grinding equipment to a 0.940-inch diameter to remove the decarburized layer. The balls&apos; hardened zones were similar to those in the previous set. The hardness of the finished surfaces was 52 to 60 Rockwell C. A slight amount of decarburization apparently remained after the removal of about 0.030 inch from the surface. Balls of this type were tested in the dry mill only. Another set of forged SAE 1095 steel balls of 1-inch diameter was heated to 1500 F and quenched

Jan 1, 1961