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By K. R. Long

Until it was defunded in 1995, the U.S. Bureau of Mines maintained a Cost Estimating System (CES) for prefeasibility-type economic evaluations of mineral deposits and estimating costs at producing and non-producing mines. This system had a significant role in mineral resource assessments to estimate costs of developing and operating known mineral deposits and predicted undiscovered deposits. For legal reasons, the U.S. Geological Survey cannot update and maintain CES. Instead, statistical tools are under development to estimate mining costs from basic properties of mineral deposits such as tonnage, grade, mineralogy, depth, strip ratio, distance from infrastructure, rock strength, and work index. The first step was to re-estimate ?Taylor?s Rule? which relates operating rate to available ore tonnage. The second step was to estimate statistical models of capital and operating costs for open pit porphyry copper mines with flotation concentrators. For a sample of 27 proposed porphyry copper projects, capital costs can be estimated from three variables: mineral processing rate, strip ratio, and distance from nearest railroad before mine construction began. Of all the variables tested, operating costs were found to be significantly correlated only with strip ratio.

Jan 1, 2011

By Gerald G. Griswold, James O. Greenslade, Cherie Tilley, Richard Reseigh

INTRODUCTION The Harrison Western Corporation, a leading Denver based mine contracting and engineering concern, is presently engaged in sinking two 1,006 m (3,300 ft) shafts for the Phillips Uranium Corporation at their Nose Rock Project, approximately 13 miles northeast of the small community of Crownpoint in McKinley County, New Mexico. The Nose Rock Project is the first attempt by the Phillips Uranium Corporation to tap the deep uranium reserves in what has become known as the Grants Mineral Belt. (See Figure 1) Project Description Phillips Uranium Corporation's plan for the large 2700 metric ton per day (2950 tons/day) mining facility calls for a series of deep access and ventilation shafts ranging from 4.27 m (14 ft) to 5.49 m (18 ft) in diameter to approximate depths of 1,006 m (3,300 ft). The initial pair of shafts consists of one production shaft and one ventilation shaft separated by a distance of 91 m (300 ft). The interbedded layers of sedimentary sandstones and shales to be penetrated by the shafts contain several major water producing aquifers, the deepest being the mineralized zone called the Westwater Canyon Member of the Morrison Formation.

Jan 1, 1981

By Paul Wellman

A computer program is presented that may be used to calculate the bare equipment cost of the major processing units for any hot potassium carbonate gas purification system. The program is designed such that, with only minor modifications, it could be used with a variety of computer systems.

Jan 1, 1968

Early in 1940 the development and sampling programmes in hand on the North and British Sections of North Broken Hill Limited were such as to necessitate the drilling of a large number of drill holes ranging up to about thirty feet in length. On the British Section, one purpose was to test the existence, width, and value of narrow lodes believed, for geological reasons, to occur in the walls of the existing workings. Another object was to definitely disprove the existence of payable shoots of ore in certain largerhodonite and quartz-garnet ("garnet sandstone") pillars which had been formerly left as unpayable.On the North Section, the main purpose of the short holes was to delineate the ore-body boundaries by drilling laterally from drives in ore, and thus enable level layout to be planned in advance of sill stoping. It was also desired to test the walls of stopes in those portions of the mine where the economic limit of mining is not rendered obvious by a clear-cut wall, but should be determined by assay. In these latter cases it was hoped to eliminate "prospecting by stoping," a procedure by which any doubts as to the existence of further good ore behind the low-grade walls were settled by continuing to stope laterally until all chance of such an occurrence was removed.LONG HOLE ROCK DRILLINGFollowing an investigation of recorded instances of similar practice elsewhere it was decided to use the rock drill for a series of trial sample holes. A 3-in. drifter was used. This was selected from those in use underground, and was given a special overhaul; had a new machine been purchased, a 4-in. type would probably have been obtained as being more suited to the work. The rods were H in. hollow round steel with a type "1" Jackrod thread. Couplings were of chrome steel, and were H in. in diameter, and 2 in. long. Jackbits (type "1" thread) in sizes from 2 in. to 4 in., with 1-in. gauge changes, gave a range of nine bit sizes. They were resharpened by hot milling, and were not milled to a definite gauge size.After sharpening, bits were sent underground without sorting into sizes, the drillers selecting the next bit with callipers. In view of the small scale of operations, it was not considered worth while to adopt special measures, such as the cold grinding of bits, which might have given a better product. Later, however, new bits were used exclusively, the idea being to accumulate enough blunt Jackbits to warrant a thorough treatment of the sharpening...

Jan 1, 1941

By R. Hendrickson

In the 1940's a top blown water-cooled oxygen lance was developed to inject oxygen into liquid iron. This process, the LD or BOF process technique, today is used in 65% of the world's steel production, and represents the largest oxygen market for temperature enhancement in steel and non-ferrous smelting applications. There are three major approaches to the use of oxygen in metallurgical processes: (1) general enrichment of the air supplied to burners or tuyeres, (2) under-flame enrichment or injection, and (3) the use of an auxiliary oxy-fuel burner as a heat source. With each of these techniques there are technical and economic trade-offs.

Jan 1, 1990

By Scott, Turner

IN 1933, the monetary metals were produced in a ratio of 6.7 oz. of silver to 1 oz. of gold, the lowest relatively for silver since the period from 1851 to 1865. At the beginning of that period, the virgin placers of California -and Australia began producing almost simultaneously; in consequence, there was an abrupt fall in the high silver side of the ratio that had prevailed through the centuries after America was discovered. The output from the Comstock and other silver-bearing lodes, located a decade after this influx of new gold began, soon restored the production ratio to its former proportion, that is, a relatively large weight of silver compared to gold.

Jan 1, 1934

By R Memary

The environmental and economic impacts of a significant dependence on fossil fuels are affecting the future of sectors such as of mining. These impacts are prompting the Australian Government to seek solutions for reducing its dependence on fossil fuels more generally, such developing clean energy and improving energy efficiency. However, limited research has been undertaken to assess the potential synergies between clean energy and mining in an uncertain global future. This paper analyses current energy use by mining in Australia and reviews the drivers and opportunities for energy efficiency and cleaner energy technologies to be coupled to mining under three future scenarios. Linkages between mining and clean energy are investigated for three global scenarios for mining and metals to 2030, developed by the World Economic Forum (WEF), namely Green Trade Alliance, Rebased Globalism and Resource Security. These scenarios are applied to assess how they could change the barriers, opportunities and trade-offs required for the development of a more sustainable energy sources by the minerals industry in Australia.

Nov 22, 2011

By Pertti Koukkari, Nagendra Tripathi, Karri Penttilä, Justin Salmine

ChemSheet is a thermodynamic multi‐phase multi‐component simulation software, which is used as an Add‐in in Microsoft Excel. In ChemSheet, the unique Constrained Gibbs free energy method can be used to include dynamic constraints and reaction rates of kinetically slow reactions, yet retaining full consistency of the multiphase thermodynamic model. With appropriate data, ChemSheet models can be used to simulate reactors and processes in all fields of thermochemistry. The presentation will cover off‐line modeling of Cu‐flash smelters and advanced thermochemical simulation coupled with on‐line process control of Cu‐Ni smelting. The presentation will describe an off‐line model of Cu‐smelter based on critically assessed properties of the Al-Ca-Cu-Fe-O-S-Si –system (slag, matte and liquid metal) by using the quasichemical model. A four‐stage reactor model (shaft, settler, uptake and bath) is used for optimizing process parameters and feed particle distribution. As a second example, an advanced thermochemical model of a Ni-Cu sulphide smelting plant will be given. The on‐line model covers the operation of treating Ni-Cu-S concentrate via roasters, electric furnace and converters, producing a high grade Bessemer matte product for further refining. The model integrates the thermochemistry of the roasters and electric furnace, and predicts important process parameters such as degree of sulphur elimination in the fluid‐bed roasters, matte grade, iron metallization, slag losses and the iron to silica ratio in the electric furnace slag. Both models can be used to assist process engineers and operators in calculating the addition rates of coke, flux and air for different feed scenarios.

Jan 1, 2014

By Charles A. Kumbe

"INTRODUCTION The Sullivan Mine was examined by Thomas L. Chapman, an engineer of the Bureau of Mines, in March 1943. Samples taken from the few mineralized exposures justified further investigation of the property. To determine whether extensive exploration of the property would be warranted, the Bureau did a small amount of trenching and underground work during April 1943, 3/ under Bureau project 1462.ACKNOWLEDGMENTSIn its program of exploration of mineral deposits, the Bureau of Mines has as its, primary objective the, more effective utilization of our mineral resources to the end that they make the greatest possible contribution to national security and economy. It is the policy of the Bureau to publish the facts developed by each exploratary project as soon as practicable after its conclusion. The Mining Branch, Lowell B. Moon, chief, conducts preliminary examinations, performs the actual exploratory work, and prepares the final report. The Metallurigical Branch, R. G. Knickerbocker, chief, analyzes samples and performs beneficiation tests.The investigations of the and Metallurgical Branches of the Bureau, as reported in this paper, were supervised by J. Hedges, district engineer for Arizona, and S. R. Zimmerly, regional engineer for the Western Region, respectively."

Feb 1, 1947

By R. L. Grayson, S. S. Peng

"Abstract. Sampling of respirable dust and analyses of samples have been partially completed for a longwall panel. Physical and compositional properties which have been characterized include:l. Respirable mass concentration, 2. Mineral composition,3. Particle size distribution by mineral,4. Particle shape distribution by mineral,5. Particle angularity distribution by mineral, and6. Respirable size distribution.Analytical techniques used in the characterization of samples are described, and results are reported with emphasis placed on relationships between the various characteristics and worker locations. Details of existing mining conditions, equipment arrangements, dust control methods and operating system parameters are presented.INTRODUCTIONThrough the work of many researchers worldwide, the health of coal miners in modern societies is now protected from dangerous exposure to respirable coal mine dust. A vast amount of research culminated in the exposure-response model of Jacobsen, et al. (1971) whi3h has been used to establish the 2mg/m exposure limit in the United States. According to the model, exposure to respirable dust for 35 years at this level or less would prevent the occurrence of a clinically significant case of coal workers' pneumoconiosis (CWP). The exposure limit, of course, must be adjusted whenever greater than five percent free silica exists in the respirable dust.The Jacobsen model was built around a mass concentration exposure, which showed the highest correlation with incidence and progression of CWP. As Morgan; et al. (1973) noted, howev.er, the quantity of respirable dust inhaled is not the only significant factor. It is noted that although mass of respirable dust correlates highest with the incidence of CWP, it is not a causal factor. Indeed, the insidious processes causing the disease occur on the cell-particle scale, requiring microscopic investigation."

Mar 1, 1989

By R. J. Evans, A. G. Revesz

Silicon films have been grown by chemical reaction on (111) silicon substrates. The surfaces were examined by various microscopic and interfero-metric methods. Surface structures are classified into two groups depending on whether the angles between the bounding planes and the (111) surface are small (<3 deg) or large (> I0 deg). A layer-gvowth mechanism is postulated to explain the topography and the influence of growth parameters. Growth proceeds by lateral expansion of the (111) layers in (211) directions, thereby forming steps. The step edges are perpendicular to the direction of expansion and are thus along (110) directions. Step bunching md surface nucleation both play an important role in modifying the flow pattern and in the step regeneration. These are influenced ver?) much by impurities, especially oxygen. Although the growth is a result of a surface-controlled ga: reaction, it is very similar to growth from an impure solution. OVERGROWTH ("epitaxial growth") of silicon is important and widely used. During the past years several investigators have observed various topographical features or so-called faults on the grown films. A study of the surface morphology gives some insight into the growth mechanism. I) EXPERIMENTAL Silicon films have been grown on silicon substrates by a method described by Theuerer.&apos; Silicon is formed by reduction of SiCl, in hydrogen. The rate of incidence of SiC1, was varied between 5 x 10"6 and 2 x 10&apos;4 moles min-&apos; cm-&apos;. The mole fraction of Sic4 in the Hz-SiCL mixture was about 5 x X Both the rate of incidence and the mole fraction were calculated on the assumption that the Hz bubbling through the SiC1, reached equilibrium saturation. Assuming uniform velocity distribution, the linear velocity of the gas in the reactor tube was estimated to be 2 cm sec-l. The temperature of deposition was varied between 1070" and 1260°C. Chemically polished p-type silicon wafers of 20 to 100 ohm cm resistivity were used as substrates. These were within 1/2 deg of a (111) orientation. The thickness of the grown n-type film was determined by two methods: a) measurement of the depth of the p-n junction taking into account the junction shift due to diffusion, b) measurement of the traces of stacking-fault tetrahedra on the (111) plane.&apos; The agreement between the two methods was better than 20 pct. The rate of growth varied between 0.2 and 4.0 pmin-&apos;. The formed films were examined by reflection and light-section microscopy, and by multiple-beam interferometry. Phase-contrast illumination revealed height differences of about 30A. For measuring heights greater than 1 p a light-section microscope3 was used. The resolution by multipke-beam interferometry4 was between 50 and 100A. Crystallographic directions on the surface were determined by X-ray and from the orientation of etch pits and stacking faults as revealed by Dash etch (I part HI?, 3 parts HNOJ, and 12 parts CH3COOH). Some specimens have been investigated by electron microscopy. Platinum-shadowing and carbon-replica techniques were used to show the fine topography and reflection diffraction to determine the structure of the grown layers. 11) RESULTS The topographical features can be classified into three groups. he first group is comprised of fine ridges (striations). The second group consists of structures, which are bounded by planes making angles of less than 3 deg with the (111) surface. They are, therefore, vicinal planes. Structures which closely resemble growth or etch pyramids from the third group would normally be bounded by perfect low-index crystallographic planes. In this case they are deformed. The angles between the bounding planes and the (111) surface are generally larger than 10 deg. The fine ridges are present, even on the smoothest surfaces, as shown in Fig. 1. They are along a (110) direction. The height differences could not be resolved with interferometric techniques. The basic characteristic structures of the second group are depressions and hillocks. These are bounded by three planes, two of them with larger slopes than the third one. The edges between the planes, as projected to the (111) surface, point in (211) directions. Various habits of these structures are shown

Jan 1, 1964

By P. J. Colbassani

Samples of mine atmospheres collected by Federal coal-mine inspectors during their inspections and investigations of coal mines, in accordance with provisions of the Federal Coal Mine Safety Act (66 Stat. 692; 30 U. S. C., sees. 451-483) are analyzed routinely by chemical methods at Bureau of Mines laboratories. When samples collected in open workings of nongassy coal mines at points not less than 12 inches from the roof, face, or rib contain 0.25 percent or more methane, the act requires the operator, during operation of such mine, to comply with the provisions of sec. 209, Title II, of the act, which pertain to gassy mines. The methane con-tents of such samples are determined by a physical method based on infrared absorption spectrometry to provide an independent check on analytical results obtained by chemical methods. This information circular describes the equipment and procedures used by the Bureau for determining low concentrations of methane in coal mine atmospheres by infrared absorption spectrometry. ACKNOWLEDGMENTS The authors are indebted to Dr. R. A. Friedel, Chief of Spectrometric Section, Branch of Coal-to-Oil Research, Bureau of Mines, for suggesting the analytical method and for furnishing valuable advice and assistance, and to J. A. Queiser of his staff for making exploratory measurements by this method; to Dr. M. G. Zabetakis of the Division of Explosives Technology for his assistance during the conduct of preliminary experimentation; and to L. B. Berger, Chief, Branch of Health Research, under whose guidance the equipment was procured and the work conducted.

Jan 1, 1958

By J. Smolensky, M. Paul

The Nordhalde is a waste rock pile resulting from uranium mining near Ronneburg, Germany. The pile contains over 27 million m3 of waste rock. Typical seepage water has a pH of 2.7 and a sulfate concentration of 10,000 mg/L. Geochemical investigations of the Nordhalde from 1993 to 1996 included drillholes, test pits, ABA and metals analyses, column tests, and a detailed review of the construction history of the pile. In 1996, eight drillholes were instrumented for monitoring oxygen and temperature. Monitoring continued for a fill year. Hourly temperature and pressure readings were taken by automated data recorder. Oxygen concentrations were measured three times per week, and periodic gas samples were obtained for complete analysis. The resulting data set is believed to be one of the most comprehensive of its kind. Effects noted elsewhere, such as thermal convection, are evident. However, unlike other data in the literature, the NordhaIde data shows a strong seasonal effect, with convection dominating oxygen transport only in the winter months. Analysis of the data allowed the amount of contaminants associated with ongoing and historical oxidation to be compared, and results were used to assess the potential effectiveness of proposed remediation measures.

Jan 1, 2000

By D. E. Andrus

This paper, which describes the milling practice at the Montana mine concentrator of the Eagle-Picher Lead Co., is one of a series being prepared by the United Slates Bureau of Mines. LOCATION The Montana mine is situated on the eastern edge of the Oro Blanco mountains at an elevation of 4,300 feet. It is in the Oro Blanco mining district, Santa Cruz County, in the southern part of Arizona, about 4 miles north of the Mexican border, 30 miles northwest of Nogales and 80 miles southwest of Tucson. Amado, a station on the Southern Pacific Railroad, midway between Tucson and Nogales, and about 40 miles northeast of the mine, is the shipping point and is reached over an excellent highway.

Jan 1, 1931

By Ihsan Berk Tulu, Gaobo Zhao, Deniz Tuncay, Syd S. Peng

Longwall mine instrumentation for measuring abutment stress distribution, mining induced immediate roof stress change and deformation, and primary/secondary support loads and deformations provides critical guidance for the design of gateroad chain pillars and roof support. Field measurement results are also recognized as the best way to calibrate numerical models that have been used to study the failure and support mechanisms. International Conference on Ground Control in Mining (ICGCM) started in 1981 and since then, there were 26 papers published in the proceedings discussing the stress and load measurements as the face advanced using various field instrumentation techniques. The focus of this paper is on summarizing the analyses of the data published in these papers. Stress/load change monitoring included the following categories: gateroad chain pillar, abutment pressure, bolt load, and pre-driven recovery room. The data shows that the magnitude of stress changes as the face advances varies considerably from panel to panel and mine to mine. However, regardless of types of stress changes, pillar stress, abutment pressure, and bolt load, there exists a rough trend of stress increase as the face advances, generally consisting of three stages, i.e., stress/load (1) initially increases steady or slowly, (2) increases rapidly, and (3) increases reaching the peaks and dropping down slowly or sharply. The stress/load increases start earlier during the second panel mining and are larger than the first panel mining. This review makes it easy for the interested persons to find valuable data for other similar projects.

Remote sensing methods have been used to evaluate vegetative growth patterns for many applications, though relatively little work has focused on tracking mine reclamation progress. For coal mines in Central Appalachia, reclamation approaches that include production of biofuel feedstocks are increasingly attractive, as these may yield significant post-mining land values and contribute to carbon-neutral energy supplies. To optimize productivity, the influence of reclamation parameters must be well understood ? which necessitates tracking biomass production over long time periods. Satellite-based estimations may offer low-cost alternatives to conventional biomass appraisals, and also the potential to provide critical input for carbon accounting at varied spatial scales. In this paper, we use biomass production experimental plots on reclaimed mine sites established by the Powell River Project (PRP) for a comparative study between satellite measurements of Normalized Difference Vegetation Index and inventory estimates of biomass under a variety of conditions. The PRP is a unique public-private partnership in the coalfields of southwestern Virginia dedicated to enhancing beneficial use and environmental protection of mined lands.

Feb 27, 2013

By Robert Hopler

The literature of explosives and blasting consists of a great variety of printed materials. These materials include technical papers, books, and articles by individuals and organizations; manufacturer’s product catalogs and brochures; handbooks offering guidance for the field blaster; complete encyclopedias on the subjects, and short entries in general-interest encyclopedias; government publications; proceedings of organizations devoted to the subjects; magazines specific to the subjects; articles in general circulation magazines; and other miscellaneous sources. In short, there is a multitude of literature on the subject, some well indexed for retrieval, but most not. This presentation will be a broad-brush look at some of the most important or interesting literature on the subject, since in no way can all the various references be mentioned, much less covered in depth. To illustrate the presentation, interesting materials from the author’s collection will be shown.

Jan 1, 2000

By I. E. Wahn, E. A. Boutin

"The Manibridge Mill is unique in its treatment of relatively high grade nickel-copper ore because in the mill design are included one 10' diam. x 10' Maxwell cell, and three 12' diam. x 12' tank cells. These large cells are used as rougher-scavenger cells. Three 8' diam. x 8' tank cells as well are used for cleaning and recleaning of the tank cell concentrate.Flexibility of flow is the main criterion in the tank cell circuit. Targets from these cells are a high grade nickel-copper product with a minimum of talcose gangue.The operation of the tank cells has been encouraging and they have performed well with both low and high grade heads, yielding a high grade concentrate product.Manibridge Tank CellsDescription:The tank cells at Manibridge consist of one 10' x 10' Maxwell cell, three 12' x 12' tank cells, and three 8' x 8' tank cells. The four large cells are currently being used as rougher scavenger cells. The three small cells are used as cleaner cells.Both sets of tank cells consist of Denver steel tank and Super Agitator Mechanisms with steel beam super-structures. The agitator mechanism has a totally enclosed ball bearing spindle housing with a cold rolled steel shaft, and a stanclard standpipe with adjustable collar.The air rings for the tanks were fabricated by Nelson Machinery. Both large and small cells have injection rings with equally spaced air holes in the bottom centre line of the ring.Air is supplied to the tank cells by a Dresser Clark low pressure air blower.The following is a table of pertinent data on the tank cells:"

Jan 1, 1974

By Alla D. Mah

Relatively pure aluminum nitride (AIN) recently has been prepared in sufficiently large amounts to permit a variety of experimental studies.4/ Several mechanical and chemical properties have been investigated, which show that this substance has good potentialities as a container for liquid aluminum, gallium, and boric oxide. The present work by the Bureau of Mines was undertaken to obtain thermo-dynamic data pertinent to the calculations regarding thermal stability and reactivity of aluminum nitride. The following measurements were made: (1) determination of the heat of formation from the elements at 298.15° K.; (2) determinations of the heat capacity over the temperature range 51° to 298.15° K. and the evaluation of the entropy at 298.15° K. therefrom; and (3) determinations of the heat content over the temperature range 298.15° to 1,800° K. These data are combined to obtain free energies of formation from the elements between 298.15° and 2,000° K.

Jan 1, 1961

By D. K. Denton, J. M. Girard, D. F. Scott, T. J. Williams

Personnel from the Spokane Research Laboratory, National Institute for Occupational Safety and Health, examined an underground pillar at the Homestake Mine, Lead, SD. Investigations involved strain relief and seismic tomography studies in the mine, and ultrasonic velocity measurements on pillar core in the laboratory. Measured octahedral normal stress was 37 MPa (5,366 psi); seismic P-wave velocities averaged 5.2 km/s (17,060 ft/s); and ultrasonic velocities at a pressure of 39.6 MPa (5,750 psi) averaged 6.3 km/s (20,669 ft/s). The difference between in-mine and laboratory velocities is attributed to the attenuation of seismic energy by mine fractures larger and more numerous than those in the samples of core measured in the laboratory. Using these results, researchers hypothesize that pillar rocks have the ability to withstand stress an order of magnitude greater than they currently sustain.