Search Documents

By Donald Thompson, Jessie Bonner, Ileana Tibuleac

Predicting ground motion from complicated mining explosions is important for mines developing blasting programs in regions where vibrations must be kept below certain levels. Additionally, predicting ground motion from explosions in complex 3D media is important for source size estimation for nuclear treaty monitoring. Both problems have been addressed under the development of a new series of programs including: 1) Generalized Fourier Methods to generate synthetic seismograms (Green’s functions) in 3D media for a moment tensor source implementation and 2) MineSeis3D, a program that simulates seismograms for delay-fired mining explosions with a linear relationship between signals from small size individual shots. To test the programs, three-component seismic recordings of three production shots at an iron mine in northern Minnesota were compared to synthetic waveforms in 3D media. Comparison of the observed and synthetic waveforms shows promising results. The shape and arrival times of the normalized synthetic and observed waveforms are similar for most of the stations. The synthetic and observed waveform amplitude fit is best for the vertical components in the mean 3D model but not as promising for the transversal components. The observed effect of spall on the waveform spectra was weak in the case of fragmentation delay-fired mining explosions. Commercial applications of the code could provide data needed for designing explosions that do not exceed ground vibration requirements posed by the United States Department of Interior, Office of Surface Mining.

Jan 1, 2005

FOR rapidly marking in geological and topographical features on parish plans, the author has used the Veeder cyclometer with very satisfactory results. A simple Veeder cyclometer, usually retailed at cycle depots at 4s., is fixed to the axle of the front wheel of an ordinary bicycle. The cyclometer is desigued to read in miles and tenths of miles, which are recorded through gearing actuated by a striker on a spoke of the bicycle wheel engaging one of the vanes of the cyclometer once every revolution.By using 80 strikers the reading would be in chains and tenths of chains; therefore the use of 8 strikers gives the reading in chains, utilizing all the figures. The cyclometer is designed to be placed on the right-hand side of the bicycle, and takes up a minimum of space, being only about the size of the top joint of the thumb. With some makes of cycles there is insufficient clearance, so the cyclometer must then be placed on the left side, and the 8 strikers made to engage the top vanes, as shown in the sketch (Fig. 1).Very accurate readings can be obtained by this instrument. The author has found by numerous tests that the maximum error...

Jan 1, 1916

By C. E. Gerity

Near Bunker, Mo., in the New Lead Belt, Ozark Lead Co. operates a 6000 tpd lead-zinc mine. Mined ore is transported to the surface in three mechanized and automated steps. The mine is developed by a rectangular-shaped sublevel haulage drift 15 ft high by 28 ft wide, driven on strike below the ore zones. Ore transfer raises were driven from the sublevel at locations near the shaft, 1500 ft distant, and on subsequent 1000 ft centers. These 6 x 5-ft raises are slashed to obtain maximum storage below dump points. These dump points are located on each mining level and are of steel and concrete construction. Spiral 12 X 24-ft inclines driven from the sub-level provide access to these levels for equipment and mine utilities.

Jan 11, 1972

By C. Meyer, J. J. Eidel

C. W. Hunt I wish to register strong disagreement with the choices of drilling sites chosen by the Continental Scientific Drilling Committee, while endorsing the stated objectives. Of special significance is the lack of any site involving the metals most needed today in the US, while 9 to 13 km of drilling are allocated to gold and silver districts and 11 to 17 km to base metal (mainly copper) districts. Why is nothing proposed for platinum group or chromite? Is this because the committee did not know of such a site? If so, I offer such a site in California (see Fig. 1). The mineralization shown in Table 1 occurs in a large peridotite body in western Tehama County, CA. Petrography has demonstrated unequivocal evidence of migrated PGE deposited in peridotite and chromite of hypabyssal nature. Active diapirism (due probably to serpentine buoyancy) above a reactivated mantle to surface conduit marks the position of the conduit. Young explosion breccia cemented loosely by volcanic glass and tuff demonstrates the significance of the conduit as the prime source of the various emissions. Deep drilling could result in major metals discoveries as well as shedding light on the grand questions of platinum group mineralization. What role water has played in this occurrence is not yet certain; but chlorine and asphaltite have been detected in and adjacent to native PGM, suggesting a major role for water. The explosion breccia suggests that this excellent site could overlie entrapped geothermal steam.

Jan 6, 1987

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

By B. A. Wilcox

ThERE are several reports in the literature which indicate that both solid-solution hydrogen and hydride precipitates can promote low-temperature em-brittlement of tantalum.1-3 For example, Imgram et al.2 showed that hydrogen additions in the range of 140 to 580 ppm promoted a ductile-to-brittle transition at slightly above room temperature in both wrought and recrystallized tantalum. This contrasts with the observation that tantalum of norma1 purity is very ductile, even at liquid-nitrogen temperature. Imgram et al. also found that hydrogen additions caused a deterioration of notch tensile properties of tantalum. The purpose of this communication is to present some limited evidence that hydrogen can also cause fatigue embrittlement of tantalum. The material used in this investigation was wrought, stress-relieved (1000°C, 1 hr), are-melted tantalum rod (5/8-in. diameter) containing the following impurities in weight percent: 0.005 C, 0.007 02, 0.0005 H2, 0.003 N2, 0.08 Cb, 0.01 W, and 0.01 Fe. Hydrogen charging was done in an atmosphere of flowing dry hydrogen for 3 hr at 600°C, followed by an homogenizing anneal in purified argon for 15 min at 600°C, and cooling in an argon atmosphere. Typical micro-structures of the hydrogen-free and the hydrogen-charged materials are shown in Fig. 1(a) and Fig. 1(b), respectively. Fig. 1(b) shows the appearance of hydride precipitates which, in many cases, formed preferentially parallel to the rod axis. The hydride dispersion was uniform across the diameter of the specimen. The fact that the precipitate was a tantalum hydride was tentatively confirmed by X-ray diffraction on a metallographically prepared surface. After hydrogen charging, chemical analyses by vacuum fusion revealed the hydrogen content to be 0.0295 wt pct. In addition, the oxygen and nitrogen contents were slightly raised to 0.0095 O2 and 0.005 N2.

Jan 1, 1964

By Harry Siewert

"The commissioning of the 4th concentrator (C4) at Freeport Indonesia in early 1998 increased total mill throughput from 130k to 230k tonnes per day. The C4 flowsheet consists of a single 38 ft diameter SAG mill, four 24 ft diameter ball mills followed by four banks of 4,500 ft3 WEMCO flotation cells.The design of the C4 rougher flotation circuit was based on the expectation that the copper and gold recoveries achieved with the 4500 ft3 flotation cells would be equivalent to or better than that achieved with the 3,000 ft3 flotation cells in the 3rd concentrator (C3) rougher circuit. This assumption was due to the fact that the C4 flotation feed size would be less than 15% +212 microns compared to the C3 rougher flotation feed size of less than 23% +212 microns. By mid 1998 it had become apparent that the C4 rougher flotation copper and gold recoveries were below those predicted.In order to determine the cause of the lower recoveries, stage by stage rougher flotation surveys were performed in all four concentrators. The results of the surveys showed that the C4 rougher flotation circuit had a lower recovery of +200 micron material than that achieved in the C 1, C2 and C3 concentrators. Through mineralogical analysis, it was determined that a majority of the copper contained in the +200 micron fractions was liberated and recoverable. This paper describes the steps taken to increase coarse particle recovery, overall plant recovery and the results achieved."

Jan 1, 2001

By Aly M. Mohammad

State and federal agencies during rehabilitation of existing bridges may require the existing bridges to be evaluated under seismic conditions. If the bridge does not perform under the seismic event, the bridge may require seismic retrofitting. Bridges are classified as: Critical, Essential, and Others according to their importance. Geotechnical considerations play a major role in evaluating the bridge behavior under a seismic event. Subsurface conditions influence the magnitude of ground acceleration and hence the forces and moments on the superstructure. This paper will provide a detailed description of the geotechnical aspects associated with the seismic retrofit evaluation for the 12th Street and 14th Street Viaducts located in Jersey City, New Jersey. The paper will also present a description of the geotechnical investigation program including seismic cross-hole surveys to determine the dynamic soil parameters, including the results of site-specific response spectra for both the 475 and 2475-year events. Liquefaction assessment methodology utilizing an equivalent factor of safety will also be described and the design method used will be summarized. In general, the pile foundation is modeled as 6x6 foundation stiffness matrix with 36 stiffness coefficients at the center of the pile cap. The seismic loading on the foundation is evaluated in a pseudo-static analysis, where the dynamic earthquake-induced loads are presented by static forces and moments. The computer program FB Pier was used to evaluate the foundation stiffness. The moments, axial loads, and shear are input into the FB Pier model. The stiffness of the foundation is determined and the results are then input into the Structural model to determine new forces and displacements. Adjustments are made until the loads are compatible with the stiffness used. The understanding of the geotechnical conditions at the 12th Street and 14th Street Viaducts and the coordination between the Bridge and Geotechnical Engineers were able to provide significant cost saving to the Owner. The Design Engineers were able to retrofit the existing Viaduct foundations with reasonable number of additional piles. It is believed that the results and finding presented in this paper will benefit both the Bridge Engineers and Geotechnical Engineers by highlighting the importance of interaction between the two disciplines.

Jan 1, 2006

By H. Tomlinson

"PURPOSE OF REPORTThe purpose of this report, which is the third of a. series on the coal mines of the Western States, is to give the findings of a study of the causes and methods of prevention of accidents from falls of root and coal in the mines of Lincoln County, Wyo. The three mines covered in this report, referred to as A. B. and C, account- for 9 per cent of the coal production in the county and nearly 9 per cent of the State's total production. For comparative purposes some statistical data are presented bearing upon the relation of injuries to their causes, to tonnage produced, to men employed, to days worked, and to days lost as the result of injuries.FATALITIES IN WYOMINGTo show the necessity for this study, Table 1 given the fatalities that occurred during 1928 in the bituminous—coal mines of the United States, of the State of Wyoming of Lincoln County, and in Mines A, B, and C, followed by a brief description of the Kemmerer coal dis-trict, its coal beds and immediate roof, thickness of cover, dip of coal beds, methods of mining timbering for roof support, roof testing, and supervision. All of these factors must be considered in any plan outlined to prevent accidents resulting from falls of roof and coal.ACKNOWLEDGMENTAcknowledgment is made to the officials of the operating companies for their cooperation and assistance during the study and collection of data to complete this report.GENERAL INFORMATIONLocation and Ownership The mines included in this report are within 18 miles north and south of Kemmerer, Lincoln County, Wyo. (fig. 1), and are owned and operated by various coal companies to supply the domestic, smelter and railroad markets. They are severed by branch lines of the Oregon Shorty Line Railroad Coal production and men employed underground in the three mines are indicated in essential detail in Table 2."

Sep 1, 1932

By · J. B. Boisvert, O. Leuangthong, T. Acorn

Optimizing final pit limits for stochastic models provides access to geologic and economic uncertainty in the pit optimization stages of a mining project. This paper presents an approach for optimizing final pit limits for a highly variable and geologically complex gold deposit. A heuristic pit optimizer is used to manage the effect of geological uncertainty in the resources within a pit shell with multiple uncertainty rated solutions. The uncertainty rated pit shells follow the meanvariance criterion to approximate the efficient frontier for final pit limits. Stochastic dominance rules are then used in a risk management framework to further eliminate sub-optimal solutions along the efficient frontier. This results in a smaller set of final pit shells that could be further analyzed for production scheduling. Additionally, the original solutions are analyzed for changes in the mining limits and two regions are targeted as potential regions for further exploration.

By · J. B. Boisvert, O. Leuangthong, T. Acorn

Optimizing final pit limits for stochastic models provides access to geologic and economic uncertainty in the pit optimization stages of a mining project. This paper presents an approach for optimizing final pit limits for a highly variable and geologically complex gold deposit. A heuristic pit optimizer is used to manage the effect of geological uncertainty in the resources within a pit shell with multiple uncertainty rated solutions. The uncertainty rated pit shells follow the meanvariance criterion to approximate the efficient frontier for final pit limits. Stochastic dominance rules are then used in a risk management framework to further eliminate sub-optimal solutions along the efficient frontier. This results in a smaller set of final pit shells that could be further analyzed for production scheduling. Additionally, the original solutions are analyzed for changes in the mining limits and two regions are targeted as potential regions for further exploration.

By Chris Larsen, Ian Orford, Marilene Renaud, Mike Cooper, Lud Strah

"An AG/SAG mill was commissioned at the Brunswick Mine concentrator in October 1998. This paper discusses the original liner design for the bi-directional AG/SAG mill, observed liner wear, subsequent liner design modifications, and benefits. The mill liners consist of steel top hat shell liners, steel end liners, rubber grates and rubber lined pulp lifters.Lifter profile and plate thickness measurements were made on monthly shop days. Trends of wear rates were used to project when liners required replacement. Wear profile information was also used to determine where liner re-design would improve wear life or minimize scrap loss. Charge motion simulation modeling was used as a tool to assist liner design modifications.INTRODUCTIONThe Noranda Inc. Brunswick Mine, located near Bathurst, New Brunswick, is a large underground lead/zinc mine with a nominal production rate of 10,000 tonnes per day. The Brunswick concentrator commenced operation in 1964 with conventional surface crushing followed by rod and ball milling to reduce run of mine ore to the required size to feed two parallel flotation circuits. In 1998 the AG (autogenous grinding) mill was commissioned for a nominal production rate of 9,000 tonnes per day replacing two surface crushing plants, three rod mills and three primary ball mills. In May of 1999 the mining rate was increased and the service of the AG mill was changed to a SAG (semi-autogenous grinding) mill with the addition of 4 inch steel balls (4% volume). The mill operates in closed circuit with 0.66 meter horizontal cyclones to produce a ground product of 90 micron nominal size (K80).The AG/SAG mill liners are steel (Norsteel, chrome-moly steel) with rubber grates and rubber lined pulp lifters.The original liner design was based on studying other AG/SAG mills and recommendations by the liner supplier, Norcast. Design factors taken into account were total cost of lining (including material and labour), protection of mill shell and impact on operating performance."

Jan 1, 2003

Diesel Particulate Matter (DPM) issues are very high profile currently in both Australian coal and metal mines and Australian states are generally moving to acknowledge and to broadly follow US 2008 final metal/non metal mine regulation limits of 0.2 mg/m3 submicron particulate matter, 0.16 mg/m3 total carbon particulate and 0.1 mg/m3 elemental carbon particulate. The real time DPM monitor is being developed on the base of the successful Personal Dust Monitor (PDM) unit. The objectives of recently completed Australian Coal Association Research Program (ACARP) study has been to finalize the design of a DPM unit, to undertake comprehensive and internationally recognized laboratory testing to evaluate the new design and to undertake an underground series of tests to establish the robustness and reliability of the new approach. Under the project Thermo Fisher Scientific has undertaken structural changes to the PDM to convert it to a DPM real time monitoring underground instrument, the D-PDM. The Pennsylvania Pittsburgh Research Laboratories of NIOSH (the group that originally contracted for the PDM development) has undertaken laboratory ?calibration or verification? testing. A phase of Australian mine robustness and engineering testing has been undertaken to ensure the instrument can effectively assist mine management to handle this health issue. Tests have been undertaken at points of expected high atmospheric DPM such as during Longwall face moves, Development RAM car, Eimco and PJB usages. The paper discusses how the monitors have performed within the underground mine environment in evaluating DPM during the various phases of the production cycle. They have closely examined the influence of aspects of the mine ventilation system. Results have been compared to alternative industry pollutant measuring approaches. The outcome of the project gives the industry access to an enhanced tool for understanding the mine atmosphere in the presence of DPM. Real time DPM monitoring will allow the industry to pin-point high exposure zones such as those encountered in coal longwall face moves where various vehicles work or in areas of constrained or difficult ventilation. Identifying of high DPM concentration zones allows efficient modification of work practices to reduce underground miners? exposure. Some outcomes of the ACARP project in this area will be discussed.

Jan 1, 2009

By William Crowe Kellogg

By now the term AFMAG has been fairly well introduced to the mining industry. Several papers have been presented and published concerning AFMAG (references 1 and 2). However, the term AFMAG remains rather new to the industry, and the exact place which AFMAG occupies in the minerals exploration field is still somewhat uncertain in the minds of many who may have use for this new and interesting method of electromagnetic exploration for conductive minerals. It is the purpose of this paper to again review the basic theory of the AFMAG system, to describe and - illustrate the equipment and data presentation as used in aerial surveying, and to provide some idea of the cost and nature of airborne AFMAG surveys. This paper is primarily of a general descriptive nature and presents AFMAG theory in a schematic rather than mathematical form; emphasis is placed on the equipment, the present method of data presentation and survey operations, since it is believed that such, information will now generally best serve to inform the mining industry of the characteristics of the AFMAG system.

Jan 1, 1960

Interest in those physical properties of minerals which might be used to good effect in prospecting is not new. Early in the nineteenth century attempts were made in th'e Cornish mines to measure the natural electric potentials set up by chemical changes proceeding in the lodes. The distortion of the earth's magnetic field by bodies of strongly magnetic iron ore received early recognition in Sweden. Treasure-finders, working on the principle of electrical induction, appear to have been invented about eighty years ago, though were probably not then applied to mineral exploration. By the end of the nineteenth century Eotvos, a Hungarian physicist, had constructed a highly sensitive type of torsion balance capable of measuring the minute distortions in the earth's field of gravitation resulting from variations in the density of the materials composing the crust. During the first decade of this century he demonstrated its value in tracing rock-salt deposits in virtue of their low density compared with the surrounding rocks. Geophysical prospecting began to be recognised as having a very definite value and its development gathered momentum. Its great expansion took place after the 1914-18 war, when its value in oil exploration was amply demonstrated, and this expansion has continued to the present time and shows no signs of abating.Divisions of Applied Geophysics.The four main divisions of applied geophysics are electrical, magnetic gravitational and seismic. With the importance of ores of radio-active metals, one might add to these a radio-active division. The first two are more important to the field of mining, but techniques based on gravitational attraction have their uses in particular cases. Seismic methods are not generally suited to the exploration of metallic ores, but have proved of enormous value in the search for petroleum. With vast quantities of oil as the prize, more money has been lavished on the deve10pment and practice of these methods than on all the others put together.Geophysical Prospecting Methods.Geophysical prospecting methods may be used to detect a mineral deposit directly in virtue of differences in the intensity of some physical attribute common to it and the enclosing country rock. Examples of this are the detection of rock-salt by gravity measurements, or of iron ore by magnetic methods. Of much wider application, however, is the indireot approach in which the aim is to determine, by geophysical means, the geological structures controlling the disposition of mineral deposits. These structures may be partly known from geological work, in which case geophysical methods are useful adjuncts. Where, because of an 'unbroken cover of overburden, no useful geological information presents itself, scout drilling or geophysical prospecting are the only alternatives. Overburden is here intended to mean any covering material not, involved in the structures controlling the mineral deposits. Prospecting for petroleum amounts to the detecting of favourable reservoir structures, and as the chief types of such are the same the world over...

Jan 1, 1950

By G A. Challis, A B. Christiel

Microprobe analyses of electrum grains in some Hauraki Au-Ag deposits indicate that gold fineness is in the range of 500 - 800 (50 - 80 per cent Au), but for most deposits the range is usually narrower than this. The electrums contain minor amounts (<0.8 per cent) of copper, arsenic, antimony, mercury, iron, and sulphur. Platinum and palladium were analysed for but were not detected (detection limit 0.24 per cent for Pt or Pd). For some deposits (eg Waihi), the average fineness values for the analysed electrums correspond fairly well with the electrum fineness determined by assay during the historic mining operations.

Jan 1, 1992

By Rudolf E. Greuer

It is undisputed that an interaction between mine fires and mine ventilation systems exists. The ventilation carries the poisonous and sometimes explosive combustion products, which constitute the greatest danger of mine fires, through the mine and it provides the oxygen on which the intensity of the fire depends. The fire, on the other hand, can produce considerable ventilation disturbances which make it difficult to predict the path along which the combustion products travel. The opinions, how serious a threat such fire generated ventilation disturbances are, vary. Where shallow deposits are mined and brisk ventilation currents are used, it is frequently felt that these disturbances are of no serious concern. Where mine workings extend over larger elevation differences and where such disturbances have been encountered and been the cause of some larger disasters, their assessment is an integral part of all fire emergency plans. The author felt that the potential of digital computers for the design of ventilation emergency plans, contrary to their acceptance for conventional ventilation planning for more than two decades, is not yet fully utilized. He designed a program for the simulation of ventilation systems under emergency conditions in particular fires. This was part of work completed for a contract with the U.S. Bureau of Mines ( Open File Report OFR 115(1)-78)

Jan 1, 1980

By M. Shapiro, L. A. le Grange, B. Henning

A paper was presented by Bateman Minerals and Metals at INFACONX (2004) describing a simplified Computational Fluid Dynamics (CFD) Model for predicting the temperature and velocity distributions in all the fluid zones of a single electrode DC Furnace simultaneously with the temperature distributions in the refractory lining of the vessel. The boundary conditions imposed on the model consisted of the arc current, external surface film coefficients and ambient temperatures. The temperature and velocity distributions in the free-board, slag and metal were solved simultaneously by coupling across the interfaces between the fluids and transportation phenomena developing in the plasma arc. A simplified model was used to describe the ex-change of energy by radiation between the arc and surfaces enclosing the freeboard region. The strengths of this model were reported as being the ability to: ?Solve the different zones and transportation phenomena simultaneously without the need to transfer partial numerical results between different numerical analysis applications. ?Solve velocity and temperature distributions without assumptions regarding internal film coefficients and additional internal temperature boundary conditions. One of the disadvantages of the model was that the energy absorbed by the process was not modelled, resulting in vessel performance predictions under heat loss conditions only. Whilst this allowed potential problem areas such as localized refractory heating to be identified, the model was only capable of predicting how these could be improved by varying the overall geometry and materials of construction. This paper presents improvements in the application software and user defined subroutines of the model as follows: ?Incorporation of surface to gas, gas to gas and gas to surface radiation models to improve the accuracy of radiative heat transfer mechanisms within the freeboard. ?Incorporation of a process energy absorption model based on a theoretical temperature dependant enthalpy curve which incorporates melting, smelting and superheating in selected areas of the bath. This enables the effect of feed distribution and power to feed ratio changes to be estimated. The effects of a commercial arc at full power on the freeboard and slag can now be simulated with increased accuracy.

Jan 1, 2007

By Patrick E. Durnal

The Richmond-San Rafael Bridge was built in the early 50s' and was first opened to traffic on August 31, 1956. Among California's longest steel bridges, it spans more than 21,000 feet across the northern portion of San Francisco Bay. It is one of six toll bridges currently undergoing seismic retrofit in the Bay area. Current retrofit criteria require the structure not to collapse in a Magnitude 8.3 earthquake lasting 45 seconds on the San Andreas Fault. The earthquake epicenter is 10 miles to the west of the Bridge, near the mouth of San Francisco Bay. Another major fault is the Hayward Fault, with a potential of a 7.5 magnitude earthquake. It is only 4 miles east of the eastern end of the bridge. The retrofit criterion is that the structure survives these earthquakes without collapse or loss of life, and that they are capable of repair within a period of one year. Therefore an energy absorbing, ductility and nominal resistance based approach to the retrofit design have been adopted for the retrofit of this bridge. Foundation Retrofit The foundation retrofits were designed to satisfy of drift criteria of 6 inches at the base of the footings, and to keep the existing H-piles from experiencing unacceptable levels of permanent soil displacement and /or structural rupture. Full-scale structural lateral load testing of BP14x89 piling, to rupture, has helped to determine the drift criteria. However recent non-linear analytical results, have led to a redesign, which may allow for 12 inches of drift. The as-built analysis of the Micropile piers determined that those piers would not exceed the 6-inch drift criteria so lateral resisting shear piles were not needed at those piers.

Jan 1, 1998

Using a cylindrical hydrocyclone with a long vortex finder as the separator, a batch sizer was developed for the fast comparative sizing of the coarse solids normally encountered in mineral pulps.Operating times as short as 2 or 3 min gave separations ranging from 16 mesh down to the subsieve sizes.Reproducibility was good and sensitivity was adequate for most applications.

Jan 1, 1968