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By L. D. Gent

This report reviews the current state of the art of remote control techniques for underground continuous miners. A delineation of aspects requiring additional data is presented. Also a summary and delineation are presented in overview form for the related section functions: roof control, haulage, ventilation, power supply and rock dusting. The automated remotely controlled continuous miner project is a long-range research effort. However, the program has been divided into intermediate steps resulting in incremental production increases throughout the program. Data are developed relating the impact of our proposed research and development accomplishments to potential productivity impact.

Jan 1, 1975

By Hal W. Hunt

Heavier loading and more efficient equipment is helping to keep driven piles competitive in America. Better Knowledge and testing of soils and support materials make it practical to use higher stresses; this is being strongly promoted by those directly concerned with timber, steel and concrete piles. Readily available point protection is increasingly used to assure penetration of piles without damage to full load bearing capability. Fabric drains are being installed with pile equipment to speed consolidation of soils. Sheet pile configuration has changed; production has been reduced largely because of imports. Dynamic checking of representative piles for load carrying capability is replacing conventional load testing of just a pile or two ? at much lower cost.

Jan 1, 1987

By T. M. Barczak, S. C. Tadolini

Pumpable roof supports provide an alternative approach to secondary support in underground mining. Unlike all other supports that are either partially or fully prefabricated prior to being transported into the mine, the pumpable support is fabricated in place in the mine entry. This reduces the underground material handling efforts and thus the injuries historically associated with in-mine support construction. On-site fabrication also facilitates application of the support in areas that are inaccessible to transportation equipment such as scoops or rail cars, making it ideal for many bleeder applications. One of the main advantages of the pumpable support is that it fully bridges from the mine floor to the roof, thereby eliminating the requirement of “topping off” the support with wooden wedges or crib blocks that soften most other support responses. This report examines the development of modern pumpable roof support technology and provides a full description of the performance capabilities of each of the support products now on the market.

Near-Infrared Spectroscopy (NIRS) Sorting in the Upgrading and Processing of Skorpion Non-Sulfide Zinc Ore In 2008 Anglo American sponsored a research project at RWTH Aachen University to assess the feasibility of the use of near-infrared spectroscopy (NIRS) for ore waste discrimination at the Skorpion zinc mine. The Skorpion mine is an open pit zinc mine located in Namibia, owned by Anglo American with an annual production of 150 000 t/a of super high grade pure zinc. Opportunities for the implementation of NIRS sorting for the Skorpion process exist to upgrade currently subeconomic material, including the marginal dump (over 2000 000 tonnes, av grade of 2.5 per cent Zn). NIRS sorting is not yet implemented or established in the minerals industry however it is a proven technology in the plastics recycling industry, where more than 2000 NIRS sorters have already been installed. NIRS sorting, a type of sensor-based sorting, is a single particle sorting technique which classifies the particles based on the absorbed/reflected radiation in the near-infrared (NIR) region. A disadvantage of NIRS is that it is a surface measurement technique, but NIRS sorting shows overall great potential for the minerals industry. Skorpion ore minerals include zinc bearing phases such as sauconite, hemimorphite, smithsonite, and hydrozincite. These display diagnostic responses in the near-infrared. There are three major absorption features that characterise the reflectance spectra of the ore bearing minerals. These are due to OH and H2O molecular bonds. The spectral response of the waste material is caused by other minerals such as non-zinc-bearing clay minerals, calcite and impure quartz. Test work showed that it is theoretically possible to separate ore material from most waste material based on spectral response in the NIR region. In addition to upgrading material by removal of waste it is also potentially feasible to classify the material based on zinc grade. A tentative correlation between zinc grade and spectral response seems to exist for the sample test suite in the NIR region.

Sep 13, 2010

By Harry Dobroski

Communications with moving tracked vehicles in a rail haulage mine pose a difficult problem. These communications take place from dispatcher to vehicles or from vehicle to vehicle via the trolley line, which is a very poor communications line. As a result, deadspots and high-signal areas can occur anywhere along the line, or signal can decrease simply as a function of distance. An analysis is made of the trolley line as a communications line, and methods of improving its characteristics are discussed. Data from inmine experiments are presented, showing actual improvements in communications. Recent Bureau developments in new hardware are also discussed. These include an adaptive speaker control for existing carrier phones and a new generation of improved carrier phones.

Heavy mineral deposits are becoming more complex in terms of their compositional variation, particle mineralogy and size distributions, and present challenges for the operation of separation equipment to achieve the required grades and recoveries. Changes in equipment design and concepts potentially provide new opportunities for the beneficiation of heavy mineral sands deposits. The development of a framework for the fundamental understanding of separator performance issues is a first step to develop new machines. This paper will present a first step analysis of electro-static and magnetic separation machines with their application to real separation scenarios.

Jan 1, 2010

By Magued G. Iskander

The deterioration of concrete, steel, and timber is a serious hindrance to construction in marine and corrosive environments. Composite materials such as fiber-reinforced polymers (FRP) can offer performance advantages for construction in these environments. In the last decade, piling made of FRP composites has been used experimentally throughout North America. However, composites face obstacles because they do not have a long track-record of use in civil engineering structures. A comprehensive review of the current experience in research, testing, design, and practice of composite piling is presented in this paper.

Jan 1, 2002

IN all wet concentration processes it is of primary importance to determine to what degree the crushing must be carried in order to obtain the maximum profit per ton of ore milled.To effect a clean separation, either by gravity or flotation treatment, between either one valuable sulphide from another, or a sUlphide from the gangue, the ore must have been subjected to grinding to such an extent that the particles to be separated are completely liberated from each other.Insufficient crushing will result in either an incomplete separation of the sulphides from each other, and thus a loss of the one sulphide in the other, or else a loss of the valuable sulphide in the gangue.This being so, the question arises whether the added cost of extra crushing would be economically warranted by the increased recovery consequent on such a step.

Jan 1, 1927

By M D. Hannington

On the southern flank ofLihir Island, a group of three volcanic cones were discovered at water depths from 1000 - 1500 m. The volcanoes are located in a narrow zone of recent seismic activity and elevated heat flow (up to 100 mW/m2). The recovered rocks consist of fresh alkali-olivine basalts, clinopyroxene-rich basalts, and porphyritic phlogopite basalts. One of the volcanoes has a recently erupted ejecta blanket (recovery of warm ash!), containing a suite of abundant mafic to ultramafic xenoliths. These xenoliths appear to represent a unique cross-section of subduction-modified mantle material sampled by volatile-rich primary fore-arc magma during its ascent to the seafloor. The most spectacular finding was the discovery of an active hydrothermal system with associated vent fauna and mineralization at Edison Seamount, and the recovery of unusually gold-rich (up to 43 ppm Au) hydrothermal precipitates in 1050 m water depth at the top of Conical Seamount, only 25 km south of the world-class epithermal Ladolam gold deposit on Lihir. The discovery of submarine hydrothermal vents associated with highly alkaline, quartz-undersaturated fore-arc volcanics represents a significant departure from similar hydrothermal systems on the mid-ocean ridges and in back-arc basins. The high gold grades in hydrothermal precipitates at Conical Seamount may indicate the first documented example of a shallow-marine epithermal system analogous to those known on land, and has important implications' for the gold potential of submarine arc environments.

Jan 1, 1995

The information age has definitely arrived and in fact has only begun to affect our business processes. Traditionally mining companies have been innovators and leaders with technology, but applying information technology systems to machines directly working on the mining extraction process poses challenges to those introducing the technology. Caterpillar is now presenting machine guidance and information systems for dozers, graders, blast hole drills, shovels, excavators, wheel loaders and trucks. These systems simply increase the flow of real information in real time and deliver it to the end users who can make informed decisions that effect real productivity gains and at the same time eliminate the role of the middle manager who used to monitor and control these activities. Technology also offers cultural changes that appear intangible, but offer significant gains to those that implement technology. Critics state that these intangible benefits are still available to traditional processes, however these intangible elements are never identified nor managed without the introduction of technology enhanced processes. The benefits of these technologies are real and dramatic, existing users offer impressive testimonials, but still the technology can be disproportionate in the time it takes to introduce to an operation. Caterpillar finds that senior to executive management needs to be a part of the technology introduction, to coordinate all departments and set technology strategies.  

Jan 1, 2000

By Frank Sames

The control of the environmental effects, especially blast vibration and airblast, has become a dominating planning criterion for most surface blasting operations. Compliance with existing regulations is generally achieved through constraints in the blast design, or monitoring programs. Commonly, blast vibration and airblast signals are rated and compared only by their maximum amplitude and the principal frequency associated with the peak.

Jan 1, 1997

By M. C. Ruiz, M. E. Godoy, J. B. Rivarola, M. W. Ojeda

The amount of Pd recovered from an exhausted olefin hydrogenation catalyst was found to depend on mixing technique, particle size, carbon percentage, chlorine flow, reaction time and temperature. Pd extraction was total when a sample in the 125-175 micrometre particle size range was chlorinated for 60 min at 723 K with 20 cm3 Cl2/min, for 60 min at 748 K with 30 cm3 Cl2/min and for 30 min at 773 K with 30 cm3 Cl2/min. No C addition was needed; the initial C content of the catalyst was sufficient for total recovery. Pd extraction was also affected by heat treatment in different atmospheres before chlorination. Treatment with O2, N2 and N2 with traces of O2 led to different degrees of oxidation of C and permitted the formation of oxidised Pd species. Thermal pretreatment in N2 with traces of O2 was most conducive to Pd extraction

Jun 21, 1905

By Thomas M. Barczak

This Bureau of Mines report investigates shield mechanics by describing the elastic response and interaction of shield components to applied vertical and horizontal displacements for various canopy and base contact configurations. This research provides information on generalized shield mechanics, which is applicable in describing the behavior of all two-leg shield supports. Utilizing mechanics of materials concepts and known kinematic relationships for two-leg shield supports, free-body diagrams are constructed for each shield component illustrating internal axial, shear, and bending moment responses required to maintain equilibrium for each load case evaluated. Predicted shield (component) responses are verified by controlled displacement of instrumented longwall shields in the Bureau's mine roof simulator (MRS). Conclusions drawn from these analyses include shield structural responses are significantly dependent upon canopy and base contact configurations. Applied displacements also significantly affect shield responses. Horizontal displacement produces different responses than those produced by vertical displacements. The direction of horizontal displacement is also significant in evaluating shield response. Applications of shield mechanics to in situ support monitoring are also discussed. An objective of this research program is to establish unique shield responses to identify in situ load conditions.

Jan 1, 1989

By R. W. Thompkins

MINE operators are concerned with temperature conditions in their mines, particularly the effects of high temperatures on the l1ealth and efficiency of tl1eir employees. This paper is written to focus attention on the variables of heat transfer between rock and air. It illustrates the difficulties of predicting the manner, and the extent, of heat transfer from theoretical concepts, prior to actual operation of a mine airway. There are ~1any sources of heat in mines. The most important is that of the rock surrounding the airway. This heat, in turn, is a product of the age of the rock, faulting, proximity to recent igneous activity, oxidation of sulphides, hot ground waters, etc. The sources of heat may be constant for any one mine, but they are far from constant when dealing with various mining districts or e1•en with a number of mines in the same district. A second source of heat is that produced by machinery in operation. Practically all the waste

Jan 1, 1962

By A. Kar, J. Mazumder

"Laser ablation is a process that can be used to synthesize novel nanoscale particles as well as to deposit thin films of various materials. Usually, nanoscale particles and thin films are formed at relatively high and low pressures, respectively, inside the ablation chamber. This paper presents a mathematical model to predict the particle size distribution in the plasma generated during laser ablation. The model is developed by considering the effects of the laser-matter and laser-plasma interactions, the Stefan condition, and the discontinuity across the Knudsen layer. The nanoscale particles are found to be located at the central region of the plasma near the target. The particles have very high velocity and temperature. A good qualitative agreement is observed between the results of this model and experimental data. IntroductionRapid solidification produces novel microstructures whose atomic arrangements and/or chemical compositions are different from those of conventional materials. The conventional materials are either crystalline or amorphous. The crystalline materials have both short- and long-range orders, whereas the amorphous materials have only the shortrange order. The nanocrystalline materials have neither short- nor long-range orders, and for this reason, they exhibit novel properties which are important for synthesizing new materials. The atoms of a nanocrystal can be classified as ""crystal atoms"" and ""boundary atoms"", where the ""crystal atoms"" have the nearest-neighbor configurations similar to the lattice configuration, whereas the nearest-neighbor configurations of the ""boundary atoms"" differ from the lattice configurations 1. Various aspects of the nanoscale materials have been discussed in Refs. [1-7]."

Jan 1, 1994

By JÖRG DEHNERT, PETER WINDISCH, Bernd Schönherrt, JENS STOPP

The Quick-Erect Stopping System (QESS) offers a new way of reducing the radon exposures of miners in Germany, especially during remediation work in old mines. The QESS is a light-weight, modular, and reusable construction kit of interlocking telescopic aluminum tubes, radon-proof foil, and expanding foam. It is designed to seal off radon-rich parts of galleries within only a few minutes. Originally, the QESS was developed to protect miners against radon exposures. Then, the QESS found the attention of several mine rescue teams at a German mining conference. The Student Mine Rescue of the Technical University Bergakademie Freiberg and the Wismut Mine Rescue carried out firstmine rescue drills in Freiberg and Schlema. Additionally, a mine rescue drill was carried out by the Front Range Mine Rescue in the Edgar Experimental Mine of the Colorado School of Mines. These drills helped to improve the systemand highlighted its potential for mine rescue operations. Now, the QESS is wellsuited for small-scale mining. The QESS can be used to seal off galleries in only a few minutes to both protect miners fromradon exposures and to support mine rescue operations. Moreover, the QESS was also successfully used in ventilation experiments.

Jul 23, 2020

By M Fallon

The full history of exploration successes, failures and related costs from initial greenfield exploration in 1987 to the current brownfield stages was analysed for the Plutonic Marymia Gold Belt of Western Australia. This belt, which had escaped the attention of turn-of-the-century prospectors and had not produced any gold until 1990, is an ideal area for a collectively exhaustive, progressive value and risk case study of expected return on gold exploration. The study analyses the progressive screening of over 200 greenfield and near mine prospects, through various stages of exploration to the establishment of 38 mining sites, ranging from a few large mines to small satellite operations. It provides empirical estimates of the historical Bayesian probability of projects advancing to successive stages of exploration, eg from reconnaissance, to systematic drill testing, resource delineation, feasibility and mine development, given a successful outcome in any exploration phase. The ratio between the estimated value of the gold discovered and the corresponding historical exploration expenditure in each year and cumulatively, ie the average cost of discovery per ounce of gold, are then computed as measures of historical return on the exploration investment in this belt. These, together with an estimate of the æresidualÆ gold endowment, ie of the number and size of possible as yet undiscovered deposits, generated through the use of rank statistics (ie ZipfÆs law), provide a basis for future strategic consideration in exploration targeting in this and similar geological terranes.

Jan 1, 2009

By Gary B. Glass

Seventeen percent of US coal production now comes from the 19 surface coal mines in the Powder River Basin of northeastern Wyoming. The Powder River Coalfield, which coincides with this topographic and structural basin, is unique to the conterminous US, in that it contains an estimated 934.4 Gt (1.03 trillion st) of in-place coal resources. At least 13.2 Gt (14.6 billion st) is a compliant, strippable reserve base. In 1993, an estimated 162 Mt (179 million st), or 98% of the coal mined in this Wyoming coalfield, came from the thick - average 30.5 m (100 ft) - subbituminous, Wyodak coalbed, or from the Anderson and Canyon coals in the one mine where the Wyodak is split into two separate coalbeds. The other 2.7 Mt (3 million st) of coal mined in the Powder River Basin in 1993 came from the School, Badger, Monarch and Deitz No. 3 coalbeds. In this "world class" coalfield, there are at least 13 other persistent, 3 to 15 m (10 to 50 ft) thick, coalbeds as well as the Big George and Lake De Smet coalbeds, which are each 61 m (200 ft) or more thick in places. None of these latter 13 coals are mined at this time.

Jan 1, 1994

By P D. Katsabanis

The dynamic tensile strength of geomaterials is known to be highly dependent on the strain rate of the load applied. This is significant in applications where the material is subjected to shock waves and impact loading. This paper proposes the use of a simplified method to determine the dynamic tensile strength of hard brittle rocks using an explosively impacted version of the Hopkinson Pressure Bar. A compressive stress wave was propagated in a sample, representative of the material of interest, by detonating a small charge at one end of a cylindrical sample. The tension wave, generated upon reflection at the free face, causes spalling in brittle materials. Strains at four points in the specimen were continuously measured and the dynamic tensile strength was determined by applying the one-dimensional wave theory.

Jan 1, 2010

By Y. Q. Li, Z. C. Shen, C. H. Zhao

The dynamic properties of the KYF-320 flotation machine which is one of the biggest flotation machines in the world were tested and then verified by the computational fluid dynamics (CFD) simulation. Aeration rate testing results suggest that he effect of circulation holes on the fluid state in the flotation cell becomes gradually smaller when the impeller speed is greater than 107 r/min. The dispersion degree of air increases with the increasing impeller speed and decreases with the increasing aeration rate, and it increases slightly when the impeller speed is greater than 107 r/min. The air holdup increases and then decreases with the increasing impeller speeds and aeration rates, and a maximum value of air holdup is shown at impeller speed of 107 r/min with a value of 12.28%. CFD simulation results are in good agreement with these testing results. Industrial-scale test was carried out using this 320 m3 flotation machine for the flotation of Cu ores. The results show that Cu content increases from 0.06% of crude ore to 1.26% of concentrate, and the S content increases from 0.39% of crude ore to 24.83% of concentrate. Moreover, using this flotation machine 5.88% of power is saved compared to other type of large flotation machine.

Jan 1, 2015