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By L. C. IlsLey

Cooperation between the United States Bureau of Mines and the Safety in Mines Research Board of Great Britain, continuous since 1924, has made possible this and other papers on safety subjects. Grateful acknowledgment is made to representatives of the Safety in Mines Research Board of the Mines Department for their assistance in arranging visits to several mine safety stations, and to F. R. Wynne, Deputy Chief Inspector of Mines, Great Britain, for arranging visits to mines in Great Britain, Belgium, Germany, and France. During the summer of 1927 the writer had the privilege of visiting the mine safety testing stations in Great Britain, Belgium, Germany, and France, in the order named. All of these countries have large coal mines, many of which are rated as gassy. Therefore, when installation of electrical equipment is contemplated, each of these countries is confronted with the same safety problem as is the United States - the development of electrical equipment that will not ignite gassy mine atmospheres which might, through neglect or accident surround the equipment. The means used by these countries in safeguarding gassy mines should therefore be of general interest to safety engineers of American coal mines, and it is proposed to give a brief survey for each of the four countries mentioned. This paper presents the second of these surveys, which covers conditions in Belgium.

Jan 1, 1929

By J. C. Engel

Recent innovations in mine safety include the use of mercury vapor lamps for mine vehicle illumination. Such lamps, however, extinguish whenever the line voltage at the machine momentarily sags or is interrupted. The lamps must then cool for several minutes before they will restart. By supplying reduced high frequency power to the lamps from an auxiliary source, it is possible to maintain ionization in the arc tubes preventing the lamps from extinguishing. Essentially an auxiliary high frequency supply, the keep alive system provides additional power to the lamps automatically whenever the lamps are in danger of dropping out. The system can also provide the operator with the ability to dim the lamps at will for periods of up to three minutes by simply interrupting the 60 Hz power to the conventional ballasts. Each unit, housed in a steel explosion proof enclosure with a volume of approximately 0.6 ft3, is capable of servicing up to six 175 watt H-39 mercury lamps and two 100 watt H-75 reflector flood lamps. A total of 16 units were produced for the USBM under this contract and its extension.

Jan 1, 1979

By Robert B. Johnson

The refraction seismic method has been used as an indirect means of exploring for fluorspar in southern Illinois by the Illinois State Geological Survey. Use of the method has been restricted to those areas where mineralization is associated with faults, a restriction necessitated by the operating principles of the refraction method. The seismic data enable the interpreter to locate fault zones in the subsurface and, under ideal circumstances, to make estimates of dip direction and magnitude and vertical displacement provided the local stratigraphic units are known and are geophysically recognizable. In this instance, refraction seismic exploration has been successful in the surface mapping of well-developed faults, both simple and complex with which fluorspar may or may not be associated. However, less clear results have been obtained where faulting has been less severe and where there are numerous accompanying mineralized joints.

Jan 1, 1964

By Robert E. Manning

At present, a need exists for more effective noise control in the coal-mining industry. In particular, new muffler designs with the required acoustic performance are needed for percussive pneumatic drills. Accordingly, the U. S. Bureau of Mines issued a contract to USS Engineers and Consultants to design a muffler capable of attenuating the noise from the air exhaust of a pneumatic drill. The specific objective of the contract was to design and deliver a prototype muffler that would attenuate the air-exhaust noise to 90 decibels on the A scale (90 dbA). The test drill used in this investigation was one used for roof-bolting purposes in coal mines. Using the combined approach of analysis by digital-computer program and experiment by simulated-noise tests, three prototype mufflers were designed and constructed at U. S. Steel Research. The mufflers consisted of a variety of resonator chambers and expansion-contraction chambers, and were of the following sizes: A muffler with a 3- by 5-inch elliptical cross section and about 8 inches in length. A muffler 5 inches in diameter and about 5-1/2 inches in length. A muffler 5 inches in diameter and about 10-1/2 inches in length. These mufflers were subjected to laboratory tests to determine their effectiveness in attenuating exhaust noise, mechanical noise, total drill noise, and simulated noise. All mufflers reduced the exhaust-noise level by about 25 dbA - from about 115 dbA without a muffler to below 90 dbA with a muffler - and thus were successful in meeting the contract objective. Field tests were conducted with the three prototype mufflers at U. S. Steel's Robena No. 4 Mine, and no icing problem was encountered. A fourth prototype muffler was designed to fit around the leg of the pneumatic drill. Tests showed that this kidney-shaped muffler also reduced the air-exhaust noise to below 90 dbA.

Jan 1, 1973

By Etienne Audibert

No satisfactory theory has yet been advanced to explain what takes place when an explosive is fired in a mixture of firedamp and air. The only means of measuring the' danger is to fire the explosive into the gas mixture and note the effect, but the conditions of firing must be chosen carefully. This report is presented in the hope that it will assist in determining what method to use. The experiments have been designed to show the effect of the principal factors involved in the conditions of firing, and the results give information that seems to have some value.

Jan 1, 1940

By Etienne Audibert

No satisfactory theory has yet been advanced to explain what takes place when an explosive is fired in a mixture of firedamp and air. The only means of measuring the danger is to fire the explosive into the gas mixture and note the effect, but the conditions of firing must be chosen carefully. This report is presented in the hope that it will assist in determining what method to use. The experiments have been designed to show the effect of the principal factors involved in the conditions of firing, and the results give information that seems to have some value.

Jan 1, 1940

By J. Brian Anderson

Jointed micropiles were investigated to support bridge foundations where shallow rock was present. In this application, micropiles would have some amount of unsupported length, and would be subject to nominal lateral loads. Five lateral load tests were conducted on micropiles to demonstrate the impact of casing joints and rock socket embedment on lateral behavior. Load tests were simulated with FB-Multipier, a hybrid-finite element program for analysis of deep foundations, for proper design of the loading apparatus and instrumentation. The micropile sections were 2 m (6.56 ft) long, 273 mm (10.75 in) in diameter, 13 mm (0.5 in) thick walled, with a 50-mm (2-in) long threaded joint. Micropiles were made of one to three casing sections and were embedded 0.3, 0.6, 1.5, or 3.0 m (1, 2, 5, or 10 ft) into rock. In each test, two identical micropiles were pulled together using a simple frame until the weaker pile failed. All micropiles were instrumented with inclinometer casings while two contained strain gages at 0.76 m (2.5 ft) intervals. Load and displacement were measured at the pile heads. Tests showed the embedment of 0.6 m, 1.5 m, and 3.0 m (2 ft, 5 ft and 10 ft) sufficiently carried lateral loads over 180 kN (20 tons). The piles embedded 0.3 m (1 ft) were not able to maintain lateral load. In general, all micropiles tested to failure exhibited a brittle failure mode where there is small lateral deflection followed by a sudden failure at the casing joint. This was demonstrated in three of the load tests. In most cases, the micropiles were stiffer and stronger in the load tests than originally predicted numerically. The final test, where piles were not loaded to failure, verified that embedding vibrating wire rebar strain meters in the grout captured the bending moment profile of the micropile. The results showed the maximum moment in this case being carried directly across the threaded joint as predicted by the preliminary models. The results of these tests were used to calibrate the FB-Multipier numerical model. Using a load test that included bending strain measurements for a match, the soil properties were adjusted to produce reasonable matches for all of the load tests.

Jan 1, 2011

By Luciana Angelita Machado

Os rejeitos gerados na mineração de carvão, sob condições atmosféricas e a possível presença de bactérias acidofílicas proporcionam a oxidação primária do sulfeto de ferro, formando sulfatos e ácido sulfúrico. Com a redução do pH da água, ocorre a mobilização de metais contidos no material, gerando a drenagem ácida de mina (DAM). A DAM causa um impacto nocivo na qualidade da água superficial ou subterrânea. Uma das tecnologias de prevenção da geração da DAM consiste no método de aditivos alcalinos. Assim, o objetivo do presente trabalho foi avaliar o controle da DAM pela mistura de rejeito de carvão com escória de aciaria elétrica do forno panela. A metodologia utilizada baseou-se nos ensaios estáticos e ensaios cinéticos. Os resultados demonstram que o rejeito de carvão gera DAM. Contudo os problemas ambientais podem ser em grande parte resolvidos pela mistura do rejeito com a escória na proporção acima de 10:10. Os ensaios cinéticos demonstram que, nessa condição, ocorre aumento do pH e redução do potencial redox e sulfatos na água lixiviada. Desta forma, a disposição conjunta de escória de aciaria elétrica do forno panela com rejeito de carvão é uma alternativa viável para o controle da geração de DAM em minerações de carvão.

Jul 30, 2018

By Otto Sandovel Zea

El compromiso de minería perfecta se limita no solo a la preservación del medio ambiente, sino a la prevención de riesgos por desprendimiento de rocas y aplastamiento en el interior de la mina. En ese sentido, el presente texto señala la factibilidad de minar a sección plena todos los tajeos a través de la simulación de las condiciones más favorables y desfavorables de la mina, determinando como la alternativa más viable la bóveda en arco. Dicha estructura otorga estabilidad a las labores de minado -en tanto da sostenimiento activo a través del (Shotcrete SFR y Pernos Hydrabolt), así como desarrolla mayor productividad y menores niveles de riesgo por desprendimiento de rocas, menores grados de sobre excavación y genera de vibraciones al haber implementado la voladura de Pre-corte en sus labores.

Sep 12, 2011

By K A. Bunker, A D. Campbell, E Ah Mu, A R. Penney

The Ernest Henry mine is a transverse sublevel cave (SLC), which is relatively unique due to the 45 degree inclination of the orebody. To economically recover ore, each sublevel is horizontally offset from the previous level by around 25 m, depending on the orebody geometry. Mine development, slotting and initial production within this zone occurs in a high stress abutment that increases in magnitude at depth. These areas are seismically active and close to the hanging wall where cave propagation is yet to initiate. High stress conditions and the close proximity to the cave seismogenic zone results in challenging geotechnical conditions in the step out zone of each level and requires management of hazards including stress driven rockfalls, rock bursts and pillar failure.This paper outlines how these hazards were forecast using numerical modelling and geotechnical monitoring. Risk management techniques included dynamic ground support design, development of a new mine layout and extraction sequence as well as delayed re-entry into seismically active areas. Ongoing monitoring, instrumentation measurements and field observations were used to track the effectiveness of the controls.Future production levels are forecast to experience increasing stress and seismicity, which will increase demand on excavations and installed ground support. Ensuring the techniques and controls for monitoring, measuring and mitigating stress and seismic hazards are enforced is essential for continued safe production.CITATION:Campbell, A D, Bunker, K A, Ah Mu, E and Penney, A R, 2016. Managing stress and seismicity in an inclined sublevel cave, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 319–328 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

By Adam Wright

"Les Mines Selbaie have been producing copper and zinc concentrates from the A-1 ore zone since 1986. This paper reviews major developments in flotation practice over that period. Firstly, ore blending strategies for Selbaie's non-homogeneous polymetallic ore are discussed. The evolution of reagent use is then reviewed, focussing on copper collector trials. A description of Selbaie's flotation columns follows. Finally, past and future developments for process control are outlined.Depuis 1986, Les Mines Selbaie produisent du concentré de cuivre et de zinc provenant de la zone A-1. Cette conférence présente !es développements majeurs en flottation qui ont eu lieu depuis ce temps. Premièrement, la stratégie du mélange de minerai non homogène polymétallique est présentée. L'évolution des réactifs utilises est démontrée, particulièrement !es collecteurs de cuivre. Par la suite !es colonnes de flottation sont presénteés et finalement !es développements futurs ainsi que ceux qui ont eu lieu dans le contrille de procédé sont expliqués.1.0 INTRODUCTIONLes Mines Selbaie, wholly owned by Billiton Metals Canada Inc., is currently mining and processing ore from a polymetallic surface deposit located 288 km northwest of Val D'or, Quebec (fig. 1). The mine produces copper concentrates containing gold and silver as well as zinc concentrates containing silver. 8000 dmt/day of ore is crushed and ground to 80% passing 49 µm, prior to processing by conventional copper/zinc differential flotation. The flotation circuits consist of both conventional and column cells (fig. 2). Detailed descriptions of the mill are available elsewhere in the literature (8,9)."

Jan 1, 1995

The status and outlook for mining, in your view. Minerals remain a major part of the world’s economic foundation. The fortunes of the mining industry rise and fall with general economic trends, but mining is no less important today on a global basis than it has been historically. Certainly, portions of the industry are critically depressed — domestic copper to name one area —but other sectors are prospering. Mineral consumption, both worldwide and in the United States, has increased steadily since the Great Depression, hitting all-time highs in 2000, the last year for which I have seen data. The highly developed economy in the United States tends to obscure the continuing importance of minerals here. But in less developed nations the critical nature of minerals is obvious and well accepted. In short, although there is no shortage of problems or challenges facing mining — there never has been — mining remains an essential business with great global opportunity.

Jan 1, 2003

Background ArcelorMittal?s (formerly QCM?s) Port Cartier iron ore pelletization operations 2 side-by-side induration furnaces each producing 578 t/h of cured pellets Firing No. 6 fuel oil and coke breeze (in bed) Very large heat losses to be addressed primarily by gas recirculation

May 1, 2011

By J Samosir, L A. Snyman

Northparkes is located 27 km north of the township of Parkes in central New South Wales, Australia. The operations consist of underground block cave mines and an ore processing plant that produces high-grade copper and gold concentrate. Production is currently sourced from the E48 Lift 1 block cave mine and open cut stockpiles. Mining commenced at Northparkes in 1994 as an open cut operation. Underground block cave mining began in 1997. Northparkes was the first mine in Australia to use the highly efficient block cave mining method, which relies on gravity and natural rock stresses to fragment the ore.An issue affecting production in 2011 was the stability of the E48 mine. A small portion of the drives on the extraction level began to deteriorate as the ground support system failed. The problem was temporarily fixed by stopping production in three extraction drives and tight filling selected areas within these drives (and drawpoints) with low-strength concrete. This action provided immediate support and stability whilst allowing time to investigate potential ground support remedies. From these investigations it was decided to use resin injection technology and additional ground support to stabilise the rock in the aforementioned extraction drives as the concrete plug was excavated in a controlled advance and sequence. This made the area safe and ensured the ongoing safe operation of the E48 mine. The redevelopment of one of these drives began late in 2011, with the remainder being progressively redeveloped over the next two years in order to maintain the extraction level stability.This paper looks at the strategies employed to safely re-open previously converged drawpoints and associated extraction drives that were subject to high abutment loading that was possibly associated with premature cave breakthrough.CITATION:Samosir, J and Snyman, L A, 2014. Redevelopment at Northparkes following significant drive closure, in Proceedings AusRock 2014: Third Australasian Ground Control in Mining Conference , pp 87–92 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 5, 2014

The roasting of sulphide ores and concentrates is often the first step in the production of metals or chemicals. In many processes, the production of sulphuric acid is viewed as a by-product, while in some plants production is an important economic factor. Regardless of the purpose, a pyrite roasting plant consists of mainly three plant sections: roasting, gas cleaning and sulphuric acid. With the addition of air, the pyrite concentrates are transformed into solid oxides and gaseous sulphur dioxide at temperatures of 600 - 1000° C. After cleaning and cooling, the sulphur dioxide in the roasting gas is further processed to sulphuric acid. Two types of reactors are used depending on the application: stationary or circulating fluid bed . For over 60 years, Outotec has progressively been developing the principle of fluidised bed technology in several different reactor types for a multitude of process applications. The versatility of the fluidised bed reactor system has manifested itself in the treatment of minerals, including solid fuels, and for metallurgical processes both in the ferrous and non-ferrous fields. Process applications have included roasting, calcining, combustion and charring of coals, as well as off-gas treatment. This paper provides a summary of the pyrite roasting technology currently used along with a simple cost comparison of pyrite roasting and sulphur burning processes.

Jan 1, 2009

The roasting of sulphide ores and concentrates is often the first step in the production of metals or chemicals. In many processes, the production of sulphuric acid is viewed as a by-product, while in some plants production is an important economic factor. Regardless of the purpose, a pyrite roasting plant consists of mainly three plant sections: roasting, gas cleaning and sulphuric acid. With the addition of air, the pyrite concentrates are transformed into solid oxides and gaseous sulphur dioxide at temperatures of 600 - 1000° C. After cleaning and cooling, the sulphur dioxide in the roasting gas is further processed to sulphuric acid. Two types of reactors are used depending on the application: stationary or circulating fluid bed . For over 60 years, Outotec has progressively been developing the principle of fluidised bed technology in several different reactor types for a multitude of process applications. The versatility of the fluidised bed reactor system has manifested itself in the treatment of minerals, including solid fuels, and for metallurgical processes both in the ferrous and non-ferrous fields. Process applications have included roasting, calcining, combustion and charring of coals, as well as off-gas treatment. This paper provides a summary of the pyrite roasting technology currently used along with a simple cost comparison of pyrite roasting and sulphur burning processes.

Jan 1, 2009

By Harold A. Watson

A method for measuring leakage of vapors into a chemical-cartridge half-mask facepiece during simulated use is described. The respirator, fitted with high efficiency cartridges, is worn in a dichlorodifluoromethane (CC12F2)--air test mixture while a series of timed activities (facial movements, varied breathing, exercise, etc.) is performed. Complementing other tightness tests, this method is useful particularly for studying face fit and the effect of facial movements on leakage. The concentration of CC12F2 within the facepiece is monitored continuously to observe the immediate effect of physical activity on leakage. A composite sample is collected simultaneously in a plastic bag as a measure of average leakage during the 18-minute test period. Leakage, reported as percent, is calculated from the concentrations of CC12F2 within the facepiece and in the test atmosphere.

Jan 1, 1970

By Org de Wet

This paper summarises the strategy for selection between a two module coal plant incorporating large, but less equipment, and a three module coal plant with more but smaller equipment. The two options were evaluated in terms of three main categories: ? Size ? size of the equipment and the effect on the process efficiency as well as the difference in physical dimensions of the plant to accommodate the larger equipment; ? Cost ? capital savings between a two and a three module plant, processing the same ROM (run-of-mine) tons per hour (t/hr); and ? Practicality ? in terms of constructability of the plant, safety of using larger equipment and maintainability of the equipment. Decisions that were taken to reduce the risk associated with size, cost and practicality on the chosen option of a two module plant will be highlighted.

Jan 1, 2006

By Alfred Petrick

This report analyzes the byproducts systems of lead, zinc, uranium, rare earths, iron, aluminum, titanium, and lithium. Specific byproduct metals covered are cadmium, germanium, indium, and thallium from the zinc system; antimony and bismuth from the lead system; vanadium, radium, and scandium from the uranium system; rare-earth oxides from the rare-earth system; and cobalt, gallium hafnium, and rubidium from other systems. The report discusses various metallurgical systems, marginal and incremental production costs of byproduct subsystems, industry structure and organization, and historical data on price, consumption, and supply.

Jan 1, 1973

By J. S. Miller

The Bureau of Mines conducted surface tests to determine the feasibility of using liquid explosives for underground rock fracturing. The effects of configuration, confinement, length, critical layer thickness, and fracture-propping sand on detonation and explosive propagation velocity of desensitized nitroglycerin were studied, using polymethyl methacrylate and glass-plate reservoirs through lengths from 3 to 12 ft, with explosive-layer thicknesses from 0.1875 to 0.0312 in and in aluminum tubes 8 ft long with diameters from 2.000 to 0.125 in. Interval and continuous detonation velocity data were obtained. Under the test conditions detonation velocity was dependent upon explosive confinement and fracture-propping sand. The detonation velocity of a confined nitroglycerin explosion in aluminum tubes can be reduced by as much as 85 percent, when the tube contains fracture-propping sand. The shape of the reservoir, whether triangular or rectangular, has little effect on the detonation velocity or explosive propagation. The critical or minimum explosive-layer thickness between glass plates, capable of supporting propagation, was 0.0312 in. The presence of a fracture-propping sand in the sheetlike layers increased the critical explosive layer thickness to 0.0625 in. In nitroglycerin-filled and nitroglycerin-sand filled tubes, the minimum tube diameters successfully tested were 0.125 in and 0.375 in, respectively.

Jan 1, 1969