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By Yi Luo

Subsidence events occurred over inactive room and pillar (R&P) mines, including abandoned mines or sealed portions of active mines, are classified as unplanned subsidence because of their timing and distribution are unpredictable. When investigating such subsidence cases, many uncertainties exist and disputes often focused on whether the observed structural damages are caused by mine subsidence or other natural or artificial causes. However, solid evidences to identify the causes are often lacking. In order to conduct a thorough and impartial investigation, good knowledge in subsidence theories and other ground control subjects and broad experience are required.

Jan 1, 2009

By Daryl E. Radcliffe, Raymond M. Stateham

The Bureau of Mines, under a Cooperative Agreement with the Bear Coal Company, Somerset, Colorado, conducted a large scale evaluation of the effect of time lapse on roof stability. Time lapse in this study is the interval between exposure and permanent support of the mine roof. The study indicates that time lapse is not a critical factor in roof stability provided permanent support is installed before catastrophic failure begins. Concurrently with the time lapse study, investigations were made of stress distribution around resin-grouted bolts, the regional stress field, and anomalous geologic conditions. The behavior of the resin-grouted bolts, at least in the Bear mine, appears to fit the Coulomb-Navier Theory. Geologic conditions are primary factors in trends of roof stability that extend across the mine.

Jan 1, 1982

By JOE SIERAKOSKI, W. R. Hardwick

This paper , which describes mining methods and practices at the Johnson Camp copper -zinc mine , Coronado Copper & Zinc Co. , Cochise County , Ariz . , is one of a series being prepared by the Bureau of Mines on mining methods , practices , and costs in various mining districts of the United States . Johnson Camp is in the eastern foothills of the Little Dragoon Mountains in secs . 23 , 24 , 25 , and 26 , T. 15 S. , R. 22 E. ( fig . 1 ) . The mining property is in the low, rolling foothills at an altitude of slightly over 5,000 feet above sea level ( fig . 2 ) . The area is covered with scattered grass and small desert shrubs . The climate is mild , with hot summers and mild winters . The average annual precipitation is about 12 inches . The nearest surface water is the San Pedro River , some 12 miles west of the mine . The property is owned by the Coronado Copper & Zinc Co. , Los Angeles , Calif . This report gives a brief history of the property , describes the general geology of the area and of the ore deposits , outlines the methods of prospecting and exploration , and gives the methods of sampling and of estimating ore reserves . Development and stoping methods are explained . Underground transportation , ventilation , mine drainage , and safety measures also are described . The last section gives a brief description of the milling practice .

Jun 1, 1957

By Alan B. Wagner

Data from seven instrumented pile load tests in Milwaukee, Wisconsin and two other instrumented load tests reported in the literature, one in Evanston, Illinois and one in Houston, Texas were reviewed. The data were for pipe piles having diameters from 9-5/8 inches to 18 inches, driven to depths between 36 and 96 feet. These data were used to develop a relationship between effective vertical stress and unit side friction and unit end bearing. These relationships were based on readily measured soil parameters, undrained shear strength, Cu, and Standard Penetration Test (SPT) values. This Beta (ß) and Nt approach and four other methods were then used to calculate the bearing capacity of the nine cases analyzed. The results from each of the methods are compared with the measured results.

Jan 1, 1991

By D. K. Steele

An 18-in-diam column water elutriator was designed, tested, and operated by the Bureau of Mines for recovering nonferrous mixed metals from automobile shredder rejects. The waver elutriator separated metals from nonmetals contained in shredded nonmagnetic rejects. The unit was constructed and integrated into a local automobile shredding operation. Nonmagnetic rejects from the automobile shredder were fed onto the surface of a column of rising water. Dense materials fell through the rising water and were collected as a sink product at the bottom of the column; medium-density materials were removed as an intermediate product in a water flow through a discharge port located between the overflow and sink; and light materials were immediately carried out in the overflowing water at the top of the column as a float product. Nearly 99 pct of the mixed metals were recovered from the nonmagnetic rejects as a 70-pct-metal concentrate. Other operating conditions yielded a 93.7-pct-pure-metal product resulting in a 93.1-pct metal recovery. Float rejects are combustibles, light plastics, foam rubber, and minimal amounts of coated and uncoated copper wire. The middling discharge contained mainly medium-density rubber, plastics, glass, rock, coated and uncoated copper wire, and frequently some thin-sheet stainless steel and wrought aluminum. Maximum metal recovery in the operating program was achieved using a water velocity of 52 fpm (650 gpm). Maximum purity was obtained with a velocity of 88 fpm (1,100 gpm). .Water was recycled through a 12,000-gal baffled clarifying tank. Entrainment water losses with the float and middling rejects averaged 50 gpt of reject feed. Records maintained by the shredder operator show a 34-pct increase in nonmagnetic metals recovery during a 1-yr operation of the water elutriator as compared to recoveries from a previously used air classification system.

Jan 1, 1983

By B. A. Hillman

Silicon is the second most abundant element on earth, exceeded only by oxygen. Silicon dioxide forms a crystalline structure of repeating SiO2 molecules which form characteristically hard, durable crystals. As a result, crystalline silica is Ubiquitous in the crustal rocks, sediments and the mineral products derived from mining. An examination of the history of studies that identify silica as a human and animal carcinogen is presented in the context of the development of a public health policy in California. The implications for the cost of conducting aggregate and other mining operations in the state are discussed.

Jan 1, 1992

By Andrew M. Leszcykowski

In 1985 at the request of the Bureau of Land Management, personnel from the U.S. Bureau of Mines examined a 27,680-acre portion of the 30,420-acre King Hill Creek Wilderness Study Area (10-19-2) in order to evaluate the mineral resources. The study area, in southwestern Idaho, is underlain by Tertiary tuffs and basalt. There are no known mining claims or prospects in the study area, and no mineral resources were identified. The Volcano mining district is immediately north, but mines there are in granitic rock which does not crop out in the study area. Oil and gas leases were offered for land in the southern part of the area, but no applications were filed, and the lease offering was withdrawn (1985). INTRODUCTION This report describes the USBM (U.S. Bureau of Mines) portion of a cooperative study with the USGS (U.S. Geological Survey) to evaluate mineral resources and potential of the King Hill Creek study area at the request of the BLM (U.S. Bureau of Land Management). The USBM examines individual mines, prospects, claims, and mineralized zones, and evaluates identified mineral and energy resources. The USGS evaluates potential for undiscovered resources based on areal geological, geochemical, and geophysical surveys. Results of the investigations will be used to help determine the suitability of the study area for inclusion into the National Wilderness Preservation System. Although the immediate goal of this and other USBM mineral surveys is to provide data for the President, Congress, government agencies, and the public for land-use decisions, the long-term objective is to ensure the Nation has an adequate and dependable supply of minerals at a reasonable cost.

Jan 1, 1986

By Shouchen Dun, Zong-Ming Li

Manipulation of hand-held objects in 3D space is a complex task. Understanding how individual digits interact with a hand-held object provides helpful information for hand tool designers, researchers, clinicians, and occupational therapists. At the object-digit interface, the contact mechanics can be represented by three force and three torque components. Six-component force/torque transducers can register all the three forces and three torques at the digit-object interface, and therefore are advantageous in the study of manipulation mechanics. The large number of force and torque signals from multiple force/torque transducers are difficult to interpret and therefore making experimental research of manipulation a challenging task. The purpose of this study was to develop a 3D visualization tool for the investigation of the contact mechanics at the object-digit interfaces during manipulation tasks. Methods A 3D stick-figure hand model was created based on digitized 23 anatomical landmarks of the hand. Five miniature 6-component force/torque transducers (4 × Nano17 for the fingers, 1 × Mini40 for the thumb, ATI Industrial Automation, NC) were used to record force and torque data at the tips of individual digits. Thirty channels of force/torque signals from the transducers were collected by a 16-bit analogue-digital converter (PCI-6031, National Instrument, Austin, TX) installed in a computer. The transducers were mounted on a custom-made rectangular aluminum handle for object manipulation. Coordinate frames were established at each transducer, on the handle, and at the base of the MicroScribe digitizer. To visualize the force vectors at the digit-tips, the coordinates of the hand landmarks in the MicroScribe coordinate frame and the force vectors in local transducer coordinate frames were transformed to a common coordinate frame defined on the handle. One healthy right-handed, male subject participated in the experimental study. During the tests, the participant sat in a chair by a testing table. The forearm was strapped to an arm holder in neutral rotation position. The instrumented handle was fixed on the testing table by a C-clamp through an adapting plate. With the hand of the subject gripped on the instrumental handle, the landmarks of the instrumented handle and the transducers, as well as the anatomical landmarks of the hand were digitized using the MicroScribe digitizer for the purpose of coordinate frame establishment and transformation as described above. The subject performed three different maximum isometric voluntary contraction tasks: (1) grasping, (2) rotating in pronation, and (3) lifting. Results The 3D hand model and representative force vector clusters in a single trial of grasping, rotating, and lifting tasks are shown in Figure 1. Each cluster was formed by displaying all the 3D force vectors during the period of “stabilized” maximum effort in a trial. The magnitude and

Jan 6, 2006

By Larry A. Haas

The U.S. Bureau of Mines is investigating ways of enhancing the high-temperature softening-melting (HTSM) properties of domestic taconite pellets. These properties, which are important for determining the performance of pellets in blast furnaces, include pellet bed contraction, pressure drop, S-value (area under the pressure-temperature curve), and softening and metal-slag drainout temperatures. Experiments showed that HTSM properties were related to the physiochemical properties (fired strengths and reducibilities) of pellets containing different levels of limestone and dolomite flux. Flux additions resulted in slightly lower green and fired pellet strengths, but improved metallurgical properties, such as reducibility. The influence of reduction conditions on HTSM properties was evaluated by varying the pellet metallization starting temperature and the carbon monoxide content of the CO-N2 gas mixture. HTSM property change was more sensitive to flux addition levels when metallization was initiated at 1,100° C with 20 pct CO in the gas stream. The S-value and the metal-slag drainout temperature were found to be the best criteria for characterizing HTSM properties. The optimum flux addition level was about 8 pct (4 pct dolomite, 4 pct limestone) or a basicity of about 1. At higher flux levels, a higher metal-slag drainout temperature was obtained.

Jan 1, 2010

By Martin Kesting

The world wide growth dynamics and the continuously growing demand for energy, results in increasing energy prices. Looking from this point, the efficient exploitation of fossil fuel deposits has become a more important factor to the production of energy raw materials than ever before. This shall be reached by an increase of the automation degree of the bucket wheel excavator in the open pit mining as well as a quality increase of the entire mining process chain. A further optimization of this operation can only be achieved by gathering additional information about the input parameters. The earlier and more exact the description of the input parameter, the greater the effectiveness of the entire process chain. To address this major issue, the RWE Power AG assigned the Institute for Transportation and Automation Technology with the research project "SIMT, Sensory Identification of Material Type and Detection of the Interfaces" [Kes07]. Presently, the control of the bucket wheel excavator is carried out manually by the operator, as well as the visual identification of the different geological layers and the energy raw materials. In this paper, a sensor-system is introduced, which was developed in order to transfer the manual material identification and detection of interfaces into an automatic online procedure. A special challenge and the main focus of this contribution is the integration of this sensor system into a bucket of the bucket wheel excavator. For measuring procedures where direct contact with the in situ material is necessary, the sensor has to be integrated into the bucket. Since direct contact with the material is not necessary, it can be integrated next to the bucket wheel. The results of a preliminary study show that although there is a broad spectrum of sensor technologies for material and interface identification, only a few are suitable for an application in on-line measuring at the bucket wheel excavator. Taking into consideration the demands on the sensor technology, the studies carried out and comparable applications of individual sensor technologies which have already taken place in practice, the integration of the following measuring systems have been realized: ground penetrating radar / reflection measurements, geo electric, resistance geo electric technology. The solution developed in the research project offers for the first time the direct integration of sensor systems into the bucket of a bucket wheel excavator. It will now be possible to test other measurement methods and sensors, not only for the ones already mentioned. As an example the integration of a triaxial accelerometer to measure the solid borne sound and vibrations concerning the cutting of different materials will be shown.

Oct 1, 2009

By Virgil A. Marple

The primary purpose of this contract was to evaluate methods and techniques by which the size distribution acid concentration of mining-related dusts can be measured. One result has been the development of a portable, battery-operated optical particle counter/ multi-channel analyzer system which can he used to determine the size distribution and concentration of mining aerosols. One important aspect of this program has been the development of a calibration technique which relates the output of the optical particle counter to the penetration of the particles through an impactor: This results in a calibration curve in terms of the aerodynamic or Stokes' diameter or the aerosol particles. Using this technique, calibrations were performed on coal, silica, Arizona road dust, potash, and rock dust (corer ore) aerosols. Another task of this program was the calibration and evaluation of the GCA respirible dust monitors (RMD) 101-1 and 301. The results of evaluation showed that the instruments were within the manufacturer's specification of ±25% of the true mass concentration up to about 15 mg/m , if the dust particles were in a size range from about 0.7 to 10 µm aerodynamic diameter. Particles smaller tan about 0.7 µm were not collected by the instrument and particles larger than about 10 µm were lose in the inlet. Other tasks included performing field studies in cooperative research programs with the Bureau of Mines personnel, development of a portable polystyrene latex generator for use in optical particle counter calibrations in the field. The incorporation of impactor classification devices on the inlets of aerosol mass measuring instruments to give mass size distributions, and a study of the density of coal particles as a function of the particle size.

Jan 1, 1977

By Robinson KJ

There has been much debate in recent years regarding the number of Geology (Earth Science) graduates produced in Australia. The key variable has commonly been assumed to be the placement of graduates in the mineral and petroleum industries. Although not wishing to deny the importance of this element, we contend that Geoscience studies should be given to a wider variety of graduates. The essence is to make students and future citizens more environmentally aware. INTRODUCTION Geoscience is fundamental to exploration and to the well-being of the minerals industry and hence the Australian economy. The value of mineral primary products exports for the past three years has been: 1895 $15.3 billion 1986 $14.8 billion 1987 $16.3 billion (Data source: B.M.R) The mining industry supplies about 40% of Australia's export earnings. However the overall value of Geoscience to the Australian economy is much greater. At the opening of the ANZAAS conference in Townsville during May 1987, Sir Bruce Watson , Chairman of the Mt. Isa Mines Ltd., made a plea for a national re-examination of the way science is taught in secondary schools. In particular he emphasized the point that the community should be more aware of the importance of Geoscience and the value of the mining industry to Australia.

Jan 1, 1989

By Thys B. Johnson

The mine system analysis and evaluation study presented in this report was part of the U. S. Bureau of Nines' Tertiary channel project conducted under the Heavy Metals program. The Badger Hill pit, located on the west end of the San Juan Ridge area, near Nevada City, California, was the site of the Bureau's field work. The objectives of this study were: (1) Determine potential alternative mining systems for some of the large tertiary channel gold-bearing gravel deposits, and (2) Identify areas of technology where further investigation would be merited because of their potential inclusion in a mining system for such deposits, The study involved the development of a mineralized block inventory, an economic block inventory, determination of optimum ultimate mining limits and a preliminary economic mining system evaluation. Computer programs were developed and utilized for each of the study phases stated above. The sampling program conducted at Badger Hill by the Bureau Delineation Group together with confidential drill hole data provided by the San Juan Gold Co. formed the basic gold values and distribution information from which a deposit model was developed. The deposit was divided into minable block units and net economic values were assigned to each block for various configurations of both open-pit and underground mining methods based on cost and performance data provided by the various Bureau of Mines Research Centers. A number of controllable variables such as: (1) Mining method (open-pit and underground), (2) depth of mining cut, (3) production rate and (4) equipment type and capacity were evaluated. The prime measures of effectiveness on which the mining systems where judged were discounted cash flow rate of return and maximum utilization of natural resources. The analysis showed that underground mining of the Six-Mile Tertiary channel gold-bearing gravel deposit under consideration was uneconomical and did not permit maximum recovery of the resources within the channel. It was also apparent that mining the Six-Mile Deposit for gold alone is uneconomical or at best marginal at a gold price less than $80 per ounce. The analysis showed that the potential for an economic mining operation within the Six-Mile Deposit exists when the gravel resources of the channel are considered together with the gold. It was determined that the highest rate of return would be realized with a 20-year open-pit mining operation yielding 745,000 ounces of -gold and 55 million cubic yards of usable gravel.

Jan 1, 2012

By Frank L. Hess

In the first cart of that little space of time that we have designated as the nineteenth century, chemistry had reached a wonderful stride. Viewed from the present heights attained by the efforts of innumerable chemists with perfected apparatus, mire reagents, air under pressure, water, gas, and electricity conducted to the desk, and. numberless other helps, it seems marvelous that chemists of that day obtained such results. In 1820, about half of the elements had. been discovered; of these discoveries, Swedes had made 15 or more, about once-third of the elements then known and nearly half of those discovered after 1700.

Jan 1, 1939

By W. Reed

During the 20th century, the increased emphasis on worker health and safety and the advent of new mining equipment and methods led to many changes in mine face ventilation practices. Efforts by government and private industry to improve and modify ventilation practices resulted in better health and safety conditions for workers. This paper examines factors that had a significant influence on mine face ventilation design during the past century. Several “milestone” events are discussed along with the impact they had on worker health and safety. Significant ventilation research efforts by government and private industry are presented. This brief ventilation history highlights innovative ventilation designs and a consistent commitment to mining health and safety.

By Philip C. Good

Red mud residue from Bayer process treatment of Jamaican bauxite was dewatered in batch and in continuous centrifuges. Solids content of the residue was increased from its original value of 20 to 25 percent to about 40 percent by centrifuging. Clear effluent amounting to approximately 40 percent of the slurry liquid was recovered containing dissolved alumina and soda values for potential recycle to the alumina plant" Addition of a chemical flocculant to the centrifuge increased capacity by about 35 percent. Manufacturer's estimate of large-scale equipment requirements, based on data collected in this investigation, was that a proposed installation for dewatering 16,000 tons per day of Jamaican red mud would require twenty-two 24-by 60-inch solid-bowl-type centrifuges. Cost analysis of a proposed installation, based on a Jamaican red mud tonnage of 16,000 per day, is included also.

Jan 1, 1968

A diverse selection of rockbolt designs and resin anchors are available for use in underground mines. Research in recent years at the UNSW Mining Research Centre led to the construction of a rockbolt pull-testing facility. This facility has subsequently been upgraded, commissioned and initial test work has been completed to verify the pull-test process. A test program has been completed with the objective to understand the load transfer mechanism and improve the general performance of rockbolts. This paper describes the results of this research. Une sélection diverse de dessins du rockbolt et ancres de la résine est disponible pour usage dans les mines de métro. Faites des recherches ces dernières années à l'UNSW que le Centre de la Recherche Minier a mené à la construction d'une facilité de l'essai de la traction du rockbolt. Cette facilité a été améliorée par la suite, le travail de l'épreuve en commission et initial a été complété pour vérifier le processus de la traction-épreuve. Un programme de l'épreuve a été complété avec l'objectif comprendre le mécanisme du transfert de la charge et améliorer la performance générale de rockbolts. Ce papier décrit les résultats de cette recherche. Eine verschiedenartige Auswahl an rockbolt-Designs und Harzankern ist dafür verfügbar, benutzen Sie in unterirdischen Bergwerken. Forschung in letzten Jahren beim UNSW-Bergbau Forschung Zentrum führte Ruckerprobung-Einrichtung zur Konstruktion eines rockbolt. Diese Einrichtung ist anschließend befördert worden, ist beauftragt worden und wird abgezeichnet, prüfen Sie, die Arbeit ist vervollständigt worden, um den Ruckprüfung-Prozeß zu verifizieren. Ein Prüfungsprogramm ist mit dem Objektiv vervollständigt worden, den Lastübertragungsmechanismus zu verstehen und die allgemeine Aufführung von rockbolts zu verbessern. Dieses Papier beschreibt die Ergebnisse dieser Forschung.

Jan 1, 2003

By J. van Lookeren

In the case of a reservoir where the oil underlies a large gas cap and overlies bottom water, production can be inzproved considerably if wells are perforated below the water-oil contact rather than opposite the oil-bearing section. The theoretical arguments for this improvement, which in some cases may be tenfold, are supported by experimental evidence. INTRODUCTION Reservoirs frequently consist of one sand body containing an oil layer underlying a thick, gas-bearing section and overlying bottom water (Fig. 1). Wells in such reservoirs are customarily opened up opposite the oil-bearing interval or, rather, opposite the lower part of this interval (Fig. 2). More often than not, it is inefficient or prohibited to blow off large quantities of gas with the oil. This im-psses a severe limitation on the drawdown, which results in low oil-production rates. Because of the small difference in specific gravity between oil and water, the latter will easily cone upwards, so that the production of water together with the oil is not prevented by this completion method. In such a situation wells should be opened deeper, in the originally water-bearing zone. The gas can be shut off by not perforating over the upper part of the interval (Fig. 3) or by a tubing hung close to the bottom of the interval (Fig. 4). Initially much water will be produced, but when steady-state conditions have been established (as depicted in Figs. 3 and 4) larger drawdowns are permissible than in a conventionally completed well, and correspondingly higher oil-production rates will result. Water cuts are only slightly higher because of the small effect of gravity on the water-oil flow distribution. CALCULATIONS The ratio of improvement has been estimated by means of approximate calculations. The completion depicted in Fig. 4 is the most convenient basis for these calculations. By postulating that vertical flow gradients can be disregarded, the Appendix shows that the well-known Dupuit formula can be obtained except for some complication due to the presence of two fluids rather than one. The Appendix makes the reasonable assumption that, for suitable boundary conditions, the oil layer occupies a constant fraction of the total fluid height throughout the reservoir. The oil- and water-production rates can thus be related to the liquid levels in the borehole as follows:

Jan 1, 1966

By R. Karl Zipf

Multiple seam mining interactions caused by full extraction mining, whether due to undermining or overmining, frequently involve tensile failure of the affected mine roof. The adverse ground control conditions may prevent mining for both safety and economic reasons. Prior researchers have identified the geometric, geologic and mining factors controlling multiple seam mining interactions. This numerical study examines the mechanics of these interactions using a modeling procedure that 1) incorporates the essential constitutive behavior of the rock such as strain-softening of the intact rock and shear and tensile failure along bedding planes and 2) captures the geologic variability of the rock especially the layering of weak and strong rocks and weak bedding planes. Specifically, the numerical study considered the effect of vertical stress, interburden thickness, and the immediate roof quality of the affected seam in both undermining and overmining situations. The models show that for overburden-to-interburden thickness (OB/IB) ratios of less than 5, interactions do not occur, and that for OB/IB more than 50, extreme interaction is a certainty. In between, the possibility of an interaction was found to depend on gob width-to-interburden thickness ratio, site specific geology and horizontal stress to rock strength ratio in addition to the OB/IB ratio. The models also showed that horizontal stress was profoundly altered well above or below a full extraction area and that these changes are likely to influence the success or failure of multiple seam mining. The role of horizontal stress in multiple seam mining interactions has received little attention in prior investigations. Four factors control the mechanics of multiple seam mining interactions: 1. vertical stress concentration 2. horizontal stress concentration 3. stress re-direction 4. bedding plane slip bands A combination of vertical and horizontal stress increase and high stress gradients in the vicinity of full extraction areas re-orients principal stresses into a very unfavorable direction. This seemingly small stress re-orientation has a profound adverse effect on bedded rock.

By Georgene Renner, William R. Yernberg, Steve Kral

ABB offers complete electrical revamps of mining shovels with ac or dc drives, drive control, frequency converters with insular gate bi-polar transistor technology, intelligent control packages and visualization. Many of the world’s shovel excavators and draglines (walking excavators) were built in the1980s. After 15 to 20 years of round-the clock operation in openpit mines, these machines start to feel their age. Electrical parts are particularly vulnerable. Their performance deteriorates and availability and productivity fall. Even with regular ser-vice and maintenance, a machine of this age will accumulate 400 hours of unscheduled downtime a year. The need for a replacement becomes pressing, but the expense is often prohibitive.

Jan 1, 2005