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By Lee T. J

The area, A, under a gamma-ray log that passes through a horizontal bed given by: A = gl/k. Here is the equivalent concentration of U3O8 in the body, l the thickness of the body, and k the calibration factor or sensitivityof the logger. The area is independent of the logging speed or logger time constant.This relationship, together with the first moment about the maximum of the log and its value there suflicient to determine the thickness, position of the centre of the bed from the log maximum and the concentration of U3O8.Numerical results obtained from artificial and field data show that the computed results arc as good as those obtained by methods such as the inverse filter technique and the iterative method. The present method yields results that arc easier to feed into an ore reserve data base.

Jan 1, 1981

By James A. Brown, Marius Botha, Christopher A. Fleming

"The technical and economic feasibility or re-processing hundreds of millions of tons of tailings in a number of historic gold tailings dams in the Witwatersrand area of South Africa is being investigated. The objective is to recover uranium and residual gold from the tailings, as well as to oxidize the sulphides to eliminate long term environmental liabilities associated with acid mine drainage. The tailings from the re-processing plant will be re-deposited in a new area far from urbanization, allowing for the rehabilitation of the real estate currently occupied by these historic tailings.The first step in the process involves a mild-regrind and mild acid leach of the tailings (pH 2.5 to 3.0) to dissolve up to 40% of the uranium. This uranium is recovered directly from the pulp by resin in pulp (RIP) with a strong base resin. The RIP tails are then treated by flotation to recover a rougher pyrite concentrate, and flotation tailings that are discarded. The rougher concentrate is cleaned to produce a final pyrite concentrate and cleaner scavenger tailings, and the pyrite concentrate is oxidized in an autoclave to leach uranium and generate acid. The autoclave discharge is combined with the cleaner scavenger tails, and the acid and ferric ions generated in the autoclave are used to leach more uranium and oxidize more sulphide in the cleaner tails. The product from the concentrate leach circuit is processed by resin in pulp for uranium recovery, followed by neutralization, cyanidation and carbon in pulp for gold recovery.The rougher float tails may be further treated to recover gold that was not recovered in flotation, but which had been liberated from the old dumps by natural oxidation of some of the pyrite over many decades. The float tails would be neutralized and treated by cyanidation and CIL to recover this liberated gold.All parts of the flowsheet have been extensively tested in the laboratory, and the critical elements of flotation, pressure oxidation and resin in pulp have been demonstrated in pilot plants. The results of the hydrometallurgical investigations are presented here."

Jan 1, 2010

By Murray Jacobson

Facts obtained by the Bureau of Mines on the dust-explosion hazard in air of materials used in the plastics industry are presented for 313 samples studied in the laboratory. Information is given on ignition temperature of dust clouds and layers, minimum explosive concentration, minimum energy required for ignition, explosion pressure and rates of pressure rise, amount of inert dust required to prevent ignition and flame propagation, and, in some instances, on the limiting oxygen concentration in an atmosphere to prevent ignition by spark and by heated surface. The effects of particle shape, additives, and resin structure on explosibility are discussed. Relative explosibility of the materials is related to the ignition sensitivity and explosion severity and is denoted by an empirical index. Recognition of the degree of hazard will facilitate adoption of adequate measures for preventing ignition and explosion during manufacturing or processing.

Jan 1, 1962

By D. R. Dolinar

Geogrids can be used as surface control on both the roof and rib in underground mines to prevent the fall of small pieces of rock and material from between the primary supports. The use of screen material such as geogrid can significantly reduce the number of ground fall injuries caused by these small rock falls. Because of the potential for reducing injuries through the use of screen, the National Institute for Occupational Safety and Health (NIOSH) has conducted tests on screen materials including geogrid to determine their support characteristics and identify parameters that can affect their performance with respect to maintaining broken or failed rock. A specially designed test frame installed in the NIOSH Mine Roof Simulator (MRS) has been used to evaluate the load and stiffness characteristics of the screen material. Two types of geogrids with various designs have been tested-a polyester yarn and a polypropylene grid. The load-displacement characteristics of these grids were determined and the load capacity and stiffness were calculated through 20in of displacement. The load capacity and stiffness of the geogrid in general are shown to be related to the ultimate tensile strength of the screen material.

Feb 27, 2013

By J. G. Donaldson

Nickel containing less than 0.01 percent of total metallic impurities was produced at the Rolla Metallurgy Research Center of the Bureau of Mines by electrodeposition from purified electrolytes. The first report on this research4 described purification of electrolytes by selective precipitation and by liquid-liquid extraction. This second report describes a procedure: or electrodepositing high-purity nickel from electrolytes purified by passing a nickel ammine solution through a column of an ion exchange resin. The nickel electroplated directly from the ammine solution without further treatment; a titanium cathode and two platinum anodes were used. The nickel deposit was dense, smooth, and adherent, and contained less than 0.001 percent each of cobalt, copper, and iron, and spectrographically detectable traces of aluminum, magnesium, and silicon. Nonmetallic impurities in the nickel metal were carbon and sulfur, each present in concentrations of less than 0.01 percent. The results of several experiments planned to purify solid nickel salts by zone refining are also reported. These salts, after purification, were intended for use in preparing electrolytes for deposition of high-purity nickel. Results were not encouraging so that the more promising ion exchange procedure was emphasized chiefly.

Jan 1, 1962

By E. D. Gardner

This is one of a series of paper's being published by the Bureau of Mines on placer mining; it is written as a supplement to Information Circular 6788, "Placer Mining in the Western United States, Part III", by E. D. Gardner and C. H. Johnson which was published in February 1935. Since Information Circular 6788 was written (1933), considerable advance has been made in the technique of mining placer gravels with power shovels and draglines. Although new washing plants continue to be built in accordance with untried designs the trend of new installations is toward proved equipment. A substantial number of plants are now being operated successfully (1937).

Jan 1, 1938

By Alfred Wild

The Kraftile Co. plant, Fremont, Alameda County, Calif.--the largest producer of glazed, structural wall units west of the Rocky Mountains--maintains modern processing facilities to evaluate and blend a wide variety of clays from several sources to produce quality products. The report desribes the prospecting, exploration, and test methods used to locate raw material sources and covers processing methods, cost factors, and trends. Also, the geologic and ceramic factors are considered in a general discussion of the economics, potentials, and requirements of clays as raw materials for ceramic tile manufacturing.

Jan 1, 1963

To improve the air quality in large-opening stone mines by developing better ventilation techniques, including appropriate fan selection in conjunction with air-coursing methods. Background Stone mines are the most common underground large-entry mines in the United States. Data from the Mine Safety and Health Administration (MSHA) for the year 2000 indicate that there were 162 active nonmetal underground mines in the United States, of which 117 were stone mines. Many underground stone mines are drift mines developed from previous quarry operations. Typically, these room-and-pillar mines have entries that are 20 ft or higher and at least 40 ft wide. These large dimensions lead to a very small ventilating pressure loss, even when significant air quantities move through the mine. This is especially true of drift mine operations where ventilating pressure losses of <0.25 in w.g. are common. Underground stone mines with shafts that are<200 ft deep typically have ventilating pressure losses that are <2 in w.g. The pressure losses through these mines are much lower than those of a typical coal mine or deep metal/nonmetal mine. Therefore, the ventilation techniques and principles are quite different. In addition, because of new MSHA regulations that limit the concentration of diesel particulate matter, these mines may need to greatly increase their ventilation airflow. Therefore, large-opening mines need a fan that can move large air quantities and operate at low static pressures. There are three fan types for mine ventilation: centrifugal, axial vane, and propeller. Centrifugal fans are uncommon in underground stone mines as they are often associated with mines requiring the highest of ventilation pressures. Axial vane fans are widely used in all types of mining operations. They are the most common fan type currently found in underground large-opening stone mines. However, they typically do not operate at low static pressures with high efficiency. Propeller fans are currently uncommon in underground stone mines. They are designed for low static pressures and large air quantities at higher efficiency. This fan type best suits the ventilation needs in large-opening stone mines?they produce large air quantities at low pressure losses. Mines with air shafts<100 ft long and at least 12 ft in diameter have fairly low mine static pressures and may also benefit from propeller fans.

Dec 1, 2002

By Frederick C. Tompkins

A complete service system was established for the monitoring of personnel exposure to N02 based upon the use of passive dosimetry. This system is structured such that minimum effort is required of the user: manufacturing, analysis, reporting, and record keeping functions are provided by the service organization. A field evaluation program was carried out in a dieselized mine to assess the performance of two passive dosimeters, the Walden GASBADGE TM dosimeter, and a tubular dosimeter developed at New York University. Side-by-side comparisons were carried out to evaluate dosimeter suitability for monitoring in the field, and to assess relative accuracy characteristics.

Jan 1, 1976

By G. Swan, E. Nordlund, P. Zhang

"SynopsisThe most widely used support design damage criterion for rockburst-prone mines is based upon kinetic energy, which is proportional to the square of the ejection velocity and is commonly expressed in terms of peak particle velocity (PPV). Field monitoring and back-analyses have shown that ejection velocities of the order of 10 m/s and higher can result from seismic events of moderate magnitude. Such velocities are much higher than those predicted using PPV obtained from scaling laws. It has also been found that the peak ground motion (i.e. PPV) on the surface of an excavation is preferentially amplified (by four- to tenfold) compared to the motion in solid rock at a similar distance from the source. However, the wave propagation and interaction processes involved within the fractured rock in generating high ground motion are very complex and are not well understood at this time.In this paper, velocity amplification was investigated by modelling the dynamic interaction between fractured rock and a free surface using a 2D discontinuum-based numerical program, UDEC (Universal Distinct Element Code). A 1D model with a fractured zone was used to represent the fractured rock. Velocity amplification, quantified by PPV, predicted at the free end of the model was 2.0–3.6 times higher than the input velocity. It was found that the wave frequency, fracture stiffness, fracture spacing, and thickness of fractured zone are the main factors that affect the velocity amplification. The results have proved that the interaction of the seismic wave and multiple fractures near the free surface strongly influences the ground motion.IntroductionSince mining-induced seismicity is almost inevitable in deep mines, ground support is generally employed to mitigate the risk of seismically-induced damage. The most widely used support design criterion for seismicallyprone mines is one that seeks to maximize the absorption of the kinetic energy (plus potential energy if a gravity component is considered) of key rock blocks. Based on this criterion, design methods for rock support were first proposed by Wagner (1984) in South Africa and later improved, among others, by Roberts and Brummer (1988) and Kaiser et al. (1996)."

Jan 1, 2015

The cyclone, or centrifugal separator, ,is firmly established in industry as a low cost separator of solids from gases.While it will also separate fluids of different densities, and solids from liquids, its main use is to remove relatively fine dusts from gases whose pr~erties are generally not greatly different from those of air. This latter phase of operation is the one that will be dealt with here.The duty of such a cyclone separating system is to take in a supply of dusty gas and separate it into its components of dust and clean gas as perfectly as possible for the least consumption of pressure head. Any separation at all causes pressure loss and, in general, the greater the separation, the greater the pressure drop needed to effect it. The percentage of dust in suspension which is separated from the gas-dust mixture is commonly called the collection or separation efficiency. Overall or &quot;true&quot; efficiency must take pressure drop into account and may be considered as proportional to the ratio of the percentage of dust collected to the resultant pressure drop. For any cyclone It will vary with different dusts.Many commercial adaptions of the simple cyclone are made solely on the basis of pressure drop improvement, without taking into account the effect on separation efficiency, probably because the latter is so difficult to assess correctly. It appears unfortunate but true that the majority of such adaptions and patent gadgets fitted to cyclones which decrease pressure drop, do have an adverse effect on separation. In other&apos; words, the true efficiency is seldom increased but often diminished.Without a knowledge of what actually goes on inside a cyclone, it is impossible fully to appreciate the real effect of a modification. For instance, it is on record that a cyclone...

Jan 1, 1949

Located in Timmins, Ontario the Porcupine Joint Venture, a pooling of assets between two existing operations (the Dome Operation of Placer Dome (CLA) and the Hoyle Pond Operation of Kinross Gold Corporation) came about on July 1st, 2002; Placer being the manager of the Joint Venture with 51% ownership and Kinross with 49%. The formation of the Joint Venture was the realization of the dream of many who could envision the benefits of the whole area being operated as one entity ? the combination of the majority of assets in the Porcupine Camp into one venture containing tremendous synergistic potential of manpower, infrastructure, land tenure and exploration development. The name Porcupine in the gold mining industry brings with it the legacy of world class gold mines; the Hollinger, McIntyre and Dome with a proud tradition of excellence. The name Porcupine brings with it the legacy of over twenty individual mining companies in operation at any one time, producing over 65 million ounces of gold.

May 1, 2003

By Z. T. Bieniawski

Geomechanics signifies the science and engineering of soil and rock materials and of rock masses. It is a field of professional practice and research that draws heavily on the elements of soil and rock mechanics. Geomechanics contributes to a number of disciplines: mining engineering, civil engineering, geological engineering, petroleum and natural gas engineering, and engineering geology (including the elements of geohydrology and geophysics). These disciplines are involved in the design and construction of such projects as mines, tunnels, foundations for structures, excavated rock slopes, dams, shafts, boreholes, oil reservoir wells, underground storage facilities for oil and gas, and hazardous waste repositories. Geomechanics allows us to improve both our environment and our quality of life. In the context of this Handbook, the scope of geomechanics is discussed mainly from the point of view of applications to mining engineering. However, the coverage of the subject mate¬rial is so comprehensive that it is relevant to other disciplines as well. Section 10 covers the field of geomechanics in a structured fashion, beginning with the fundamental principles and leading into practical applications in mining engineering. Throughout the treatment of the subject, knowledge of geologic conditions is assumed since this is discussed in other sections of the Handbook. An important feature of this section is a series of practical examples illustrating the various aspects of geomechanics. Since geomechanics is concerned with both soil and rock mechanics, Chapter 10.1 introduces the fundamentals of soil

Jan 1, 2008

By Kung-Lee Wang

SUSTAINED growth characterized the U.S. economy in 1964. Many new peaks were achieved in production, sales, employment, employee earnings, and business profits. At the end of 1964, the economy had experienced 4 years of uninterrupted expansion, and the greatest net gains in output for all postwar cyclical advances had been registered. There were no indications of the various weaknesses which have previously characterized advanced stages of business expansion. Both gross national product (GNP) and national income were 6.7 percent higher than in 1963. In 1964 GNP totaled $628.7 billion, a gain of $39.2 billion over the 1963 figure. On an overall basis, prices rose 1.75 percent in 1964. The real volume of output of goods and services (GNP in constant dollars) increased by 5.0 percent ill 1964; this was more than the 3.8-percent gain in 1963 but less than the 6.6 percent gain in 1962. The 1964 output gain also exceeded the average 3.7 percent annual increase for the postwar period. Congress authorized a two-stage tax reduction designed to further stimulate economic growth and employment. The tax cut favorably affected the 1964 economy in the following ways: By helping to boost personal income, corporate profits, and industrial production; by accelerating the pace of consumer spending and business capital expansion; and by increasing employment, thereby reducing unemployment to 5 percent. Three major problems remained unsolved. These were unemployment of 3.7 million persons, poverty conditions among more

Jan 1, 1965

By M. Beth McClenaghan

This paper summarizes diamond exploration techniques used in glaciated terrain, focusing on indicator mineral and geochemical methods applied to glacial sediments. Understanding the ice flow history, depositional history, and stratigraphy of glacial sediments are essential to successful sampling, interpretation and follow-up of indicator mineral and geochemical anomalies related to kimberlites. Kimberlite indicator minerals survive glacial transport over long distances and the relative abundance of each mineral in till is a function of the primary mineralogy of individual kimberlites. Indicator mineral distributions observed at a regional scale define the net effect of glacial dispersal, often along different ice flow directions. Local-scale distributions define individual dispersal trains. The medium sand (0.25 to 0.5 mm) fraction of heavy mineral concentrates prepared from glacial sediment samples is best suited for indicator mineral surveys. The application of till geochemistry to diamond exploration is increasing because it is significantly cheaper than indicator mineral analysis and it can be performed quickly. The <0.063 mm (silt+clay) and 0.5 to 2.0 mm (coarse sand) fractions provide the best geochemical contrast between background and kimberlite-rich till. Kimberlite pathfinder elements that provide good contrast include Ni, Cr, Ba, Co, Sr, Rb, Nb, Mg, Ta, Ca, Fe, K, Ti and REE, the relative importance of which will depend on kimberlite composition as well as that of the surrounding bedrock.

May 1, 2002

By S. Atallah

A survey was conducted relating to the current practices for the classification of hazardous locations in coal preparation plants. Several plants processing bituminous, anthracite and lignite coal in Pennsylvania, West Virginia, North Dakota, Colorado, Montana and Wyoming were visited. Coal preparation plant operations and designers as well as MESA inspectors were interviewed. The National Electrical Code was discussed with selected members of the NFPA committee and electrical equipment manufacturers. Data provided by MESA on fire and explosion accidents in coal preparation plants were examined. The requirements of the pertinent Federal Regulations, National Electrical Code, National Electrical Manufacturers Association and Underwriters&apos; Laboratories were compared and evaluated. This report consists of two parts. Part I: "Analysis and Review" provides a summary of the findings. Part II: "Recommended Guidelines" consists of recommended uniform guidelines that may be used for interpreting the National Electrical Code as it applies to the classification of hazardous areas in coal preparation plants.

Jan 1, 1977

"Energy efficiency in mining and minerals processing has attracted considerable public and industry attention because of the significant quantities of energy consumption involved. In this context the question of what are worthwhile targets for energy efficiency improvements ought to be of the highest priority. It is however worth taking a step back to avoid falling in the trap of taking preconceived ideas that have been reiterated repeatedly before as gospel. The aim of this paper is to highlight areas where new or alternative approaches could potentially be the better way forward. Some may come as a surprise to conventional industry thinking. Ultimately any such solutions are attractive to practitioners not just in an environmental but also in an economic sense, and hence should be targeted through applied research and development efforts. This paper highlights key aspects of each group of opportunities and some of the individual approaches to provide an overview of the current status quo.MINING INDUSTRY POWER UTILISATION – WHERE IS THE BIGGEST BANG FOR THE BUCK?The question of where is the biggest bang for the buck when trying to determine worthwhile targets for energy efficiency improvements has not always been reported on broadly enough, typically because industry practitioners operate in specific areas of expertise and comfort zone. Looking beyond the familiar doesn’t always come easy. Any technology or methodology consideration to address energy efficiency needs to take into account the context of alternative opportunities of superior value or risks not achieving desired uptake. The following sub-chapters have been ordered by magnitude of improvement potential as best as is possible, starting with the biggest first, and the smallest last. Some may be a surprise relative to conventional mining industry thinking."

Jan 1, 2016

By Poltak Sinaga

PT Kaltim Prima Coal?s 13-km (8-mile) overland conveyor (OLC) was commissioned in 1991. It is a conventional three-roller, 35 degree trough belt type. Cost and performance optimization during initial design resulted in a 5.4-m/sec (17.7-ft/sec) belt speed, 1,000 mm- (40 in.-) belt width to convey 1.35 kt/h (1,490 stph) and 7 Mt/a (7.7 million stpy) of coal. Despite a high initial figure, the belt speed was lifted to 6.5 m/sec (21 ft/sec) in 1996 to accommodate mine throughput in-crease. In 2002, a new low loss ST2100 1,100 mm- (43 in.-) wide belt replaced the ST2250 that was due to be changed-out. An upgrade project was initiated at the end of 2003 to further increase the belt speed to increase the OLC capacity to 30 Mt/a (33 million stpy). Upgrading the OLC by increasing the belt speed was the lowest capital option. Increasing belt width and/or modifying the trough angle to have larger cross sectional area was not an economical option because it would require expensive changes and significant down time of the OLC. To achieve 30 Mt/a (33 million stpy), the belt speed had to be increased to 8.5 m/sec (28 ft/sec). Although such high belt speed looked feasible, there was no information at that time of other OLC operating at such high speed. There was a risk that the conveyor would not operate safely and reliably at higher speeds. This risk was escalated by the fact there was no facility to lower or fine-tune the belt speed once the higher belt speed was implemented.

Jan 1, 2009

By Jerome Apt

This report presents the methods and results performed pursuant to the U. S. Bureau of Mines contract entitled "Noise Abatement in Mining Machinery," Number H0122054. 2.1 Background Until the Congress of the United States created and passed Public Law 91-173, the Federal Coal Mine Health and Safety Act of 1969, there were no directly-applicable standards for noise exposure for underground coal miners.1 Section 206 of this law, approved December 30, 1969, provided for standards of noise to be applicable to each coal mine. It is as follows:

Jan 1, 1975

By J. F. Stenebråten, W. P. Johnson, D. R. Brosnahan

Carbonaceous material (CM) from ores of varying preg-robbing activity from Barrick Goldstrike Mines Inc. (BGMI), Nevada, was characterized in terms of its functional group content, hydrocarbon content, elemental composition, and humic acid content. FT-IR analyses showed neither the presence of hydrocarbons nor of carboxylic, phenolic, or sulfhydrol functionalities. FT-IR bands present included C=C stretching in aromatic rings and C-O-C stretching, indicating presence of oxygen as ether linkages in the carbon matrix. Calculated atomic oxygen to carbon (O/C) ratios did not reveal a trend between maturity of CM and preg-robbing behavior, possibly due to low resolution of electron microprobe analysis. However, the atomic O/C ratios agree with other chemical analysis, indicating that the organic carbon is very mature, similar to or higher in grade than anthracite coal.

Jan 1, 1999