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By J. C. Fowler

[This i.untra t hds bmii III c'IIILt fur till- past 1':?:u yrlr;, Till-- wurir pnrfor rw:it '. ,JS hlui.rn dawn Ilttf lit Iu i eel i ih?IS( S. 1 hesrt aIII, Phase I Candor tlri I a lest It) donurnSlrale SeiSrrlir nurihudS to hu USi!d lot ttlr? rti?tei thin and Iu" ainnl ul trapped rrlinc:rs hitting (-)it the roof with a harnrner, Phase I' Design and cunStrur.t a permanent Seismic monitor System to rrlunrtur roof (ails arm r:xploslun', III ,r 'Vol king mine. Phase III - Ire dII an an i i irr for sVstl rtl Ii i`'Smltur air quality in till, niitii iiH II ? ir,iti tin; niln !III ;I I ,, i; Phase I V - Conduct 11(21 d tests of the seismic IT IUnit UT ieq system fur a period nl two 11IUIIIIIS. Phase, V - Condirct three test periods of the seismic system over a period of six mimilis. Detailed reports covering the wurk. done in Phases I, 11, and IV have been i : . r tr I - i t report will, therefore, cuni.entrate on the work perfurmed in Phases III anti V.]

Jan 1, 1975

By A. M. Bryukhanov, A. G. Mnukhin

The report states accident rates for gassy/dusty coal mines represented as an ergatic system "man – machine - environment" with further analysis by the method of conditional probabilities. A coal mine has been analyzed with allowance for the attending personnel, equipment and environment as a sequence of events and states. Probabilities of operational states have been determined and prediction of mine behavior has been made on the basis of investigation findings for equipment and the personnel states, and analysis of the environment (i.e. mine and mining conditions). Utilization of expert estimation methods has been considered for determining major operational parameters of gassy/dusty mines. The importance of standardized values of permissible occupational risks (permissible probability of accident, PA) is demonstrated. It is also stated that a procedure is essential to determine these values, involving regular check-ups of the integral safety criterion at all mines and further development of customized recommendations for individual mines on efficient improvement of accident situations. Methodology to determine the assessment criteria has been developed and scientifically substantiated for permissible accident rates in hazardous industries.

Jan 1, 2003

By T. M. Ruff

A prototype mucking machine designed to operate in narrow-vein stopes was developed by Foster- Miller, Inc., Waltham, MA, under contract with the U.S. Bureau of Mines. The machine, called a compact loader-trammer, or minimucker, was designed to replace slusher muckers in narrow-vein underground mines. The minimucker is a six-wheel-drive, skid-steered, load-haul-dump (LHD) machine that loads muck at the front with a novel slide-bucket system and ejects it out the rear so that the machine does not have to be turned around. To correct deficiencies of the tether-remote-control system, a computer-based, radio-remote-control system was retrofitted to the minimucker. Initial tests indicated a need to assist the operator in guiding the machine in narrow stopes. An automatic guidance system that used ultrasonic ranging sensors and a wall-following algorithm was installed. Additional tests in a simulated test stope showed that these changes improved the operation of the minimucker. The design and functions of the minimucker and its computer-based, remote-control system are reviewed, and an ultrasonic-sensor-based guidance system is described.

Jan 1, 1992

By Sheridan J. Rodgers

Improved methods of dust control in the metal and nonmetal mining industries were studied. Preliminary dust surveys were made at selected mines and three mines were chosen for additional studies. Dust control effectiveness was evaluated using full shift gravimetric sampling and GCA Dust Monitor readings. Analyses for free silica content and particle size distribution were conducted. A belt washing system which was used to control dust at a transfer point was evaluated. The average reduction of respirable dust was 48% and the average reduction of total dust was 78%. The belt washing system not only maintained the work place within compliance but reduced maintenance problems along the beltway by 90%. Exhaust ventilation at a crusher was evaluated for control effectiveness. Ventilation along with operation of the crusher control room under slight positive pressure, maintained the work place within compliance. An exhaust ventilation system was designed for use at an underground rotary dump. Although the system was not installed or evaluated, details on the design are given. High expansion foam was used at an ore chute in an attempt to control dust at the draw point and loading point. Results indicated that foam did not effectively control dust.

Jan 1, 1978

By Jeff Whyatt

Deformation of underground salt, trona and potash mines is generally time dependent, providing for gradual adjustment of strata to mining induced stresses. Time dependence can allow for higher extraction ratios provided eventual failure can be tolerated. However, this eventual failure can be violent if creep deformation can shift stress and potential energy to strong, brittle geologic units. The mine failure case studies reviewed here illustrate this process. Yield pillars and defects in bridging strata figure prominently in these cases. Yield pillars provide local and temporary support to the roof, temporarily delaying the cave; and allowing extraction ratios and overburden spans to increase beyond the long term capacity of overlying strata. Defects (faults, voids, thinning) of strong overburden strata reduce the critical span, sometimes to less than panel width. Analyses of many of these cases have focused on a cascading pillar failure mechanism, but recent work and this review point to failure of strong overburden strata as the essential element. The suddenness of failure and attendant seismic events pose hazards to miners and, in some cases, to those on the surface. Characterizing these failures is a first step towards recognizing and managing the risk of catastrophic collapse in underground mines.

Jan 1, 2008

By L D. Queen

"An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation. The Tifalmin porphyry copper district is located in the Star Mountains roughly 35 km north-east of the Ok Tedi mine. The district is a cluster of temporally and geochemically related porphyry copper deposits and their associated skarns. It covers an area of roughly 10 × 6 km and comprises at least three intrusions (Olgal, Futik and Kum Kom) where drilling has demonstrated the presence of porphyry copper mineralisation, and another three intrusions (Rattatat, Unfin and Pad 48) where porphyry copper mineralisation is strongly suggested by surface investigations and geochemical or geophysical signatures.Copper and gold mineralisation was first discovered in the area in the 1960s as part of the regional exploration program by Kennecott that located Ok Tedi. The mineralisation is associated with poly-phase porphyritic diorites, quartz diorites and tonalites that intrude the Upper Eocene to Middle Miocene Darai limestone and underlying Cretaceous to Eocene Feing Group. Radiometric K-Ar and U-Pb zircon ages cluster between 4 and 2 Ma for both the mineralised and post-mineral intrusions. In addition to porphyry-type mineralisation, variable amounts of calc-silicate and/or magnetite skarn occur near the contact of most of the intrusions. Mineralisation in the Olgal and Futik porphyries occurs as chalcopyrite replacement of mafic minerals and in a stockwork of micro-veinlets. Mineralisation mostly occurs in the intrusions but is also observed in hornfelsed siltstones and sandstones of the Feing Group on the southern margin of the Olgal intrusive body. Quartz veining is uncommon. Secondary magnetite is commonly associated with the highest copper and gold grades. Sericitic alteration is most prominent in the mineralised hornfels. Structurally, the area is dominated by syn- to post-mineralisation thrusting from the north. At least one of the deposits (Olgal) appears to be truncated at depth by a thrust fault.CITATION:Queen, L D, 2015. The Tifalmin porphyry copper gold district, Star Mountains, Western Papua New Guinea , in Proceedings PACRIM 2015 Congress, pp 357–360 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 18, 2015

By Jorge Vargas Fernández

El presente artículo describe la relación entre la cultura y los recursos mineros a través del tiempo y las acciones para mantener dicha relación, dada la importancia que tiene para el desarrollo y seguridad del Perú.

Mar 1, 1971

By Robert W. Decker

This report presents a survey of published novel coal cutting (mining) concepts and a brief discussion of each one. A preliminary evaluation follows which identifies promising concepts, emphasizing reduced dust generation and economic production potentials. The promising concepts are then studied more deeply and evaluated in more detail with recommendations given for further development action. The concepts recommended for further work include: Roan and Pillar Mining: Deep Cutting Continuous Miner Linear Cutting Rotary Head Miner Longwall Mining: Oscillating Continuous Water Jet Miner Deep Cutting Shearer

Jan 1, 1981

By Reda M. Bakeer

"An approach slab is the roadway segment that immediately follows a bridge intended to provide a smooth transition between the two elements. Some approach slabs have developed rough rideability with time due to differential settlement between the roadway embankment and the bridge. Soils in south Louisiana are generally poor and highly compressible and, therefore, pile-supported approach slabs were occasionally used. Timber piles of variable lengths are driven into the soft soils where no appreciable toe support exists. This resulted in the soils both supporting loads through shaft resistance and yet experiencing long-term consolidation settlement. Field testing and review of the records of over 120 approach slabs constructed in south Louisiana yielded the conclusion that their performance is primarily governed by negative skin friction (downdrag) imposed on the relatively short timber piles. A software (TU-DRAG) was developed to evaluate the deflection profile of a pile-supported approach slab based on its geometry and conditions of the underlying soils. It evaluates the effect of dragload considering the number and spacing of the piles at each transverse row and their variable lengths along the approach slab. TU-DRAG was utilized in the design of two transportation related projects which have been in service for more than 10 years.INTRODUCTIONThe problem of differential settlement at bridge approaches or “the bump at the bridge” has been recognized for many years. Research studies (1986, 1989, 1997, 2009 and 2013) by the Transportation Research Board (TRB) and the Federal Highway Administration (FHWA) provided comprehensive evaluations of the performance of bridge approach slabs by assessing their field conditions and construction and maintenance records. Various states have also performed their own studies to investigate the performance of bridge approach slabs. The studies considered various types of structures including soil- and pile-supported approach slabs, integral bridge abutments and open-end abutments. Recommendations were provided for the design of new structures and for maintaining and repairing existing structures. Guidelines were offered regarding tolerable movements of bridges and their foundations based on measurements of vertical and horizontal movements of 580 bridges Moulton (1986). Vertical and horizontal movements greater than 102 mm (4 inches) and 51 mm (2 inches), respectively, were considered intolerable. Tolerable limits for angular distortion (differential settlement to span length) were suggested to be 1/250 and 1/200 for continuous and simple spans, respectively. It was reported that a differential settlement greater than 13 mm (0.5 inch) at the bridge interface would be sufficient to constitute a “bump” requiring mitigation."

Jan 1, 2017

By M. Ksiazek

Keywords: Thermal conductivity, thermal diffusivity, flash method, specific heat capacity, manganese ore Manganese ferro-alloys manufacturing involves a combination of quality raw materials and an energy source to produce high-quality products with low energy consumption. The thermal properties of manganese raw materials such as ores, sinters, and briquettes, are among the many factors that determine the amount of energy needed for processing. Thermal expansion, thermal diffusivity, conductivity, and apparent specific heat capacity of solid samples and compacted powder samples of manganese ores were examined from room temperature to 1000 °C. The effect of porosity (of the materials used) on the thermal properties was also investigated. The laser flash method and a pushrod dilatometer were used.

Jan 1, 2011

By Andrés Gonzalo Reyes Unda

Este trabalho de investigação foi realizado com a intenção de obter uma rota alternativa de lixiviação de ouro para minérios de baixo teor para uma planta industrial que adsorve ouro atualmente pelo processo CIL (Carbon in Leaching) na região da Ilha Cristalina de Rivera (ICR). Foram realizados testes em garrafões de 20 litros para estabelecer critérios de operação e dimensionamento de uma planta de lixiviação em pilhas permanentes para tratar 1.000.000 toneladas de minério por ano de minério de baixo teor (0,45 - 0,65 g/t) com granulometria menor que 12mm e com produção anual podendo alcançar de cerca de 455 kg de ouro.

Aug 16, 2017

By J. J. Forbes

The activities of the Bureau of Mines include the development and testing of self-contained oxygen breathing apparatus and other devices for respiratory protection, the development and tasting of devices for detecting dangerous or noxious mine atmospheres, and the training of men in the mineral industries in the use and care of this equipment to enable them to render effective service in mine rescue and recovery operations following mine fires and explosions, or under other conditions where irrespirable gases may be found in mines or mining plants. The first use of self-contained oxygen breathing apparatus for com- bating mine fires and explosions in the United States dates back about 30 years. Previous to that time, exploration for any distance ahead of fresh air was virtually impossible without great risk to life; moreover, the men called upon to render service at mine disasters were not well-versed in the properties and physiological effects of gases likely to be encountered. It was also impossible to work ahead of fresh air to restore ventilation, and if many stoppings were blown out by an explosion, air had to be introduced into whole areas or sections at once without knowledge of the conditions ahead; moving an explosive mixture of methane and air over live fire had to

Jan 1, 1938

By L. Yuan, A. C. Smith

To provide insights for the optimization of ventilation systems for U.S. underground coal mines facing both methane control and spontaneous combustion issues, a computational fluid dynamics (CFD) study was conducted to model the potential for spontaneous heating in longwall gob areas. A two longwall panel district using a bleeder ventilation system with a stationary longwall face was simulated. The permeability and porosity profiles for the longwall gob were generated from a geotechnical model and were used as inputs for the CFD modeling. In this study, the effect of methane emissions from the mined coal seam, including the longwall face and overlying rider seam reservoirs on the gob gas distribution was considered. The spontaneous heating is modeled as the low-temperature oxidation of coal in the gob using kinetic data obtained from previous laboratory-scale spontaneous-combustion studies. Unsteady state simulations were conducted, and the effects of the coal’s apparent activation energy and reaction surface area on the spontaneous heating process were also examined.1

By Ronald E. Triplett, George K. Burke, Bernard H. Voor

To accommodate larger double-stack rail cars through a tunnel, the existing active tracks were to be lowered. The tunnel is an elliptical, horseshoe-shape with concrete base support, removal of which would jeopardize the tunnel integrity, particularly since the soils beneath part of the tunnel floor included soft, saturated silt overlying rock. Grouted bar anchors combined with a SuperJet soilcrete strut replaced the existing support in situ prior to floor lowering. Close cooperation and detailed timely engineering support provided a quality project. Project design and construction, ground improvement methods, and the performance of the work are described.

Jan 1, 2001

By G Liu

Seventy-nine gold deposits and prospects have been discovered in theJiamusi region of northeast China, and constitute one of the most important gold metallogenic belts in China. All these endogenic gold occurrences can be subdivided into three main deposit types: 1. porphyry related; 2. metamorphic-intrusive hosted, and 3. sediment-hosted deposit.   The first two types of gold deposit are spatially and temporally related to Mesozoic Yanshanian granitoid intrusions with hydrothermal activity channelled along crustal-scale fissures. The ultimate cause of the Yanshanian magmatism is considered to be the subduction of Pacific oceanic lithosphere beneath the Eurasian continent. In contrast, the chemical sediment-hosted deposit is typified by the Dongfengshan gold deposit, and genetically related to Proterozoic sedimentation and Mesozoic igneous activities.

Jan 1, 1995

By David van Cleave, David L. Rome

Whether you buy your minicomputer from a manufacturer or another vendor, the first thing you must do is define your needs. With good planning, the initial cost will be low and your return on investment will be maximized over the long term. Involving all members of your staff who will he using the new computer in the planning phase is also important. Their participation will alleviate any potential concerns they may have about new equipment, and their suggestions will provide valuable input for your specifications. After you define your proposed system, survey available hardware and software. The survey will help you in the next step, preparation of specifications. The specifications, along with a quote request, are then sent to various manufacturers. Consider the Manufacturer When selecting your minicomputer, one important item to consider is the manufacturer. Remember, when you buy a computer, you're also buying the services of a computer company. A firm that makes a commitment to its customers and provides a product that is field tested before releasing it for sale is preferable. Examine the company's maintenance and support packages, since every machine requires preventive maintenance. Does your manufacturer or original equipment manufacturer (OEM) support service sites in your area? Has their service record been commendable? Will they provide training for your personnel and a supply of circuit boards so you can retain a degree of self-service autonomy? Three methods of buying a computer involve the manufacturer, an OEM, and the systems house. Buying direct from the manufacturer means you go straight to the source, using no middleman. This gives you maximum flexibility; you can consider every alternative and many possible combinations of computers, peripherals, and software until you find exactly the right system for you. The OEM buys computers direct from the manufacturer and builds them into his own computerized, special purpose product. He usually sells a complete package, including software and hardware, and often noncompetitive equipment as well (a scientific or engineering instrument, for example), designed for the mining market. Because he offers a packaged product, the OEM can often charge less for the system than if you put the pieces together yourself. In many ways, the OEM also provides a unique system. And while the OEM sells a packaged solution, he also usually has the special market knowledge necessary to modify the system to meet your unique needs, if necessary.

Jan 11, 1981

By J. R. Nettle

The purpose of these studies by the Federal Bureau of Mines was to determine the feasibility of refining low-grade hafnium by an inert-gas-shielded molten-salt electrorefining technique to produce a hafnium metal meeting reactor specifications. The techniques were adapted from those used success-fully for titanium electrorefining. Three electrolytes containing hafnium chlorides were developed from which deposits having a Brinell hardness of 170 or below were recovered. A KC1 + NaC1 + HfC14 electrolyte produced deposits in the hardness range of 140 to 165 Brinell. Deposits with a hardness range of from 132 to 152 Brinell were pro-duced from an electrolyte composed of KC1 + LiC1 + HfC14. A third electrolyte composed of NaC1 + K3HfC17 produced deposits with a hardness as low as 139 Brinell. In a fourth electrolyte, composed of NaC1 + K2HfF6, a measure of refining was accomplished, but under the test conditions no metal meeting specifications was recovered; none was softer than 174 Brinell. A number of metallic impurities were reduced in quantity by the electro-refining process, notably iron, which normally was reduced from 250 p.p.m. to less than 50 p.p.m. Magnesium generally was reduced from 680 p.p.m. to less than 80 p.p.m. Manganese content was also reduced by the electrorefining process. Sponge containing 90 p.p.m. Mn yielded deposits containing a maximum of 50 p.p.m.; some deposits contained only 10 p.p.m.

Jan 1, 1961

This document is Volume II of a two-volume report on underground and surface coal mine fires occurring between 1950 and 1977. Volume I discusses the methods of data acquisition, data analysis procedures, results and conclusions. This volume contains (1) a master list of all fire incidents obtained from MSHA reports, (2) an annotated bibliography of all MSHA reports, journal articles on selected incidents, and non-reportable fires (appendix), and (3) indexes to be used in accessing incidents in the master list and annotated bibliography. These three types of information provide the reader with a complete summary of coal mine fires during the period from 1950 through 1977 and a convenient means to locate incidents of specific interest. The body of this volume is organized around two tables and a series of indexes. The two tables are master lists of underground and surface fire incidents. They are followed by 14 indexes keyed to the master list and annotated bibliography. The appendix contains three different parts: o The annotated bibliography of MSHA fire reports (one section each for underground and surface mine fires) o The annotated bibliography of journal articles about selected fires from the MSHA bibliography o A listing of non-reportable fires (one section each for underground and surface mine fires) Descriptions of the contents and use of each of the three major components of this volume (i.e., master list, indexes, and appendix) are presented in Section 2.0.

Jan 1, 1979

By Syd S. Peng

Introduction The most commonly used ground control design in coal mining is the determination of pillar size by various pillar strength formulae for mine layout (Bieniawski, 1983; Holland, 1973; Hustrulid, 1976; Obert and Duvall 1967; Wilson and Ashwin, 1972). However, there have been few documented case histories concerning the validity of those strength formulae. Recently there are indications that those strength formulae tend to overdesign considerably. From a safety point of view, there is nothing wrong with overdesign. But an overdesign with large chain pillars reduces the flexibility of machine movement and decreases production. It also reduces coal recovery and, thus, shortens the reserve's life. This is especially true for small operators who own a limited reserve. Those small mines, through past practices or out of necessity, experiment with smaller pillars than those predicted by the strength formulae. Conclusive ev¬idence has been collected that points to the need of a new concept of coal pillar design. Two case studies will be cited to illustrate this point. 3-D US pillar strength formulae Figure 1 shows a sectional layout of a one-unit mine. The seam was about 1.3 m (50 in.) thick with a uniform cover of 64 m (210 ft). A house was located near the center of the section. The homeowner demanded that no surface subsidence and domestic well dewatering should ever be allowed as a result of underground room-and-pillar mining. Physical properties - strength and Young's modulus - of the rock strata including coal were obtained by testing small samples in the laboratory. The uniaxial compressive strength of the coal was 3660 kPa (823 psi). Using various pillar strength formulae, the homeowner recommended that square chain pillars be at least 11 m (35 ft) wide. The coal company, however, desired to pursue optimum coal recovery in the safest and most economical manner. They engaged in three-dimensional finite element analysis of the section taking into account the complete stratigraphic sequence of the overburden. Results indicated that the section can be developed by 5.5 m (18 ft) wide entries at 21 m (70 ft) center-to-center. In retreat, the pillars can be splitted along both centerlines leaving a stump pillar of 5.5 m (18 ft) square at each of the four corners. The 5.5 m (18 ft) square stump pillars still maintained a safety factor of 1.5, although the safety factors calculated by various pillar strength

Jan 11, 1986

By Randal Martin

Recently, questions regarding the influence of atmospheric temperature and humidity levels on airblast levels have arisen at a number of blast sites. Humidity is alleged to have contributed to high levels of disturbance within communities surrounding blasting. In some cases, local regulatory agencies considered adopting guidelines to specify humidity and temperature ranges under which blasting cannot take place. However, it is normal blasting industry practice not to consider humidity or temperature effects, in the absence of inversions, on airblast levels. When blasting is conducted in the vicinity of residential structures, the influence of weather on the propagation and attenuation of airborne noise from the blasting site is always a concern. Sound naturally attenuates in air with distance from the source. A part of this attenuation is attributed to divergence at the airblast wave front, while the remainder of the attenuation is an accumulation of various factors that include temperature and barometric pressure, absorption in air due precipitation and vegetation, wind and temperature gradients, atmospheric turbulence and topography (Beranek, 1971). Wind speed and wind direction, as well as vertical and horizontal temperature gradients can cause airblasts to focus in local regions surrounding blasting operations and may result in air pressures greater than expected. In fact, wind and temperature inversions can actually increase sound levels with distance from the blast site. Close to the blast site, the effects of inversions may be negligible but may exceed 10 dB at 800 m or greater (Davis and Cornwell, 1991).

Jan 1, 2001