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The coalmining industry in most countries has, at various times, suddenly been confronted with a decrease in demand for coal. Readjustments made to reduce productive capacity to match the reduced demand for coal have often resulted in hardship to mineworkers, loss of capital investment to mineowners and loss of coal reserves. The consequences of the methods of readjustment adopted in the past have contributed to the low esteem in which coalmining has come to be regarded by a large section of the gel).eral public in many countries.Four sections of the coalmining industry, representing different periods of time, different countries, and different methods of industrial organisation have been examined:Great Britain and the U.S.A. during the inter war years, the post war European Coal and Steel Community, and post war Great Britain under the National Coal Board. An assessment has been made of the methods adopted in each case to reduce productive capacity to match a reduced demand for coal. Finally the fundamentals of the problem-as it affects the coalmining industry of any country-are considered, and possible solutions put forward.During the 1950's, surplus productive capacity was a problem in many coalmining countries, including Australia and New Zealand. As a rule no techniques are developed beforehand to solve problems introduced by a sudden decrease in demand for coal. The situation is usually tackled by a series of short term decisions based on expediency, which often in the long run only aggravate the problem.

Jan 1, 1961

By M. Karsten

Platinum mines in the Bushveld Complex are located in areas with a high geothermal gradient. This means that, compared to, for example, gold mines of the Witwatersrand region, high rock temperatures are encountered at relatively shallower depths. Thus air cooling and refrigeration need to be considered at early stages in mine development. Another factor that influences air cooling and ventilation requirements is the use of trackless diesel equipment for loading and hauling broken rock. At shallower depths it will be more cost-effective to locate the cooling and ventilation equipment on surface, whereas for deeper mines the more cost-effective option is to locate cooling equipment underground. For intermediate depths, trade-off studies need to be undertaken to determine the optimum mix between more cooling and less air or more air and less cooling, as well as the optimum location for this cooling equipment. Factors that are taken into account include power requirements, positional efficiency, and additional infrastructure requirements. Traditionally the approach has been to ventilate ?all of the mine all of the time?. However, with increasing power costs and growing pressure to ensure sustainability, this strategy must be modified to apply ventilation and cooling on demand. In other words, both cooling and ventilation equipment should be operated only when needed and should be adjusted to the demand at the time. Obviously there will be areas that will need to be ventilated (and cooled) continuously (for example, for dilution of flammable gases), but this can be built in to the overall strategy. In addition, in devising ventilation on demand (VoD) strategies, occupational criteria relating to exposure to gases, noise, and heat need to be taken into account. This paper discusses options available for implementing energy-efficient ventilation and cooling systems and suggests ways of changing traditional thinking in the overall ventilation and cooling of mines. Efficient ventilation and cooling designs can play a major role in improving sustainability and reducing energy costs and carbon footprint.

Jan 1, 2012

By J. Patterson

"Acid Mine Drainage (A.M.D.) formed from oxidation of disposed pyritic wastes presents a potential pollution hazard for Equity Silver Mines Limited and the mining industry in general. Failure to collect and treat these acidic effluents can eventually affect the quality of receiving streams and endanger aquatic life forms. Treatment and discharge of A.M.D. to the receiving environment must comply with stringent anti-pollution laws.Wastes mined at Equity Silver Mines Ltd. are predominantly acid generating and must be handled according to a materials management plan to minimize impact on the environment. Effluent collection and treatment facilities have been constructed to address the short term environmental concerns with reclamation and research programs being developed to address and monitor abatement measures for control over the long term.The purpose of this paper will be to offer a brief overview of these measures. Key topics for discussion will be: kinetics of Acid Mine Drainage, acid generating potential, water treatment and sludge handling, special wastes, waste dump construction, waste rock amendments, bacteriocide research, simulations, and reclamation measures. Programs designed to evaluate impact on the receiving environment, although they form an extensive part of the program, will not be discussed in this paper.INTRODUCTIONEquity Silver Mines Limited is located in the Central Interior of British Columbia, within the Omineca Division, 35 kilometers southeast of Houston Mining and approximately 575 kilometers by air north-northeast ofVancouver (Figure 1).The deposit consists of three economic mineralized zones: The Southern Tail, Main and Waterline Zones. Mining of the Southern Tail commenced in April, 1980 and was completed in the first quarter of 1984. Main Zone production was initiated during the last quarter of 1983 and the Waterline Zone remains undeveloped to-date. Remaining reserves are in the order of four years contingent on favourable metal prices. The three deposits (Figure 2) occur within a window of interbedded volcanic and minor sedimentary rocks. The older volcanic sequence is bounded on the west by a small granite-like stock and on the east by a gabbro-monzonite complex. All are overlain by a series of younger lava flows."

Jan 1, 1988

By Rob Sloan, Simon Yu, Rob Robison, Mark Schmidt

"In 2000-2009, Highland Valley Copper (HVC) tested new generation 660 mm cyclones supplied by various manufacturers in an aim to replace existing first generation 762 mm cyclones without success. Due to plant infrastructure limitations, new generation larger (838 and 800 mm) cyclones were not feasible. In 2010, an approach of testing hybrid 800 mm diameter cyclones was initiated by HVC. The hybrid cyclone consists of an 800 mm cyclone upper head section and the use of existing 762 mm cyclone conical sections. Three hybrid 800 mm cyclones were engineered and fabricated, targeting a throughput of 850-950 mtph and were installed in the E line cyclone cluster. Since starting operation on September 20, 2011, three hybrid 800 mm cyclones have been running at combined throughput ranges of 750 to 1050 mtph. Based on plant Daily Met Reports, the test hybrid cyclones demonstrated a decrease in misplacement of coarse copper bearing material to the cyclone overflow and better cyclone efficiency when compared to the existing 762 mm cyclones at the same throughput. The hybrid 800 mm cyclones also demonstrated significantly higher capacity per unit when compared to the existing cyclones. Based on the improvement demonstrated in the full plant trials, HVC decided to install the new hybrid 800 mm cyclones in all five grinding lines starting in July, 2012. A more detailed discussion of the full plant trials and initial results of the first complete retrofit of E line will be presented. INTRODUCTIONHighland Valley Copper Partnership (HVC) is Canada’s largest base metals mine and one of the world’s largest producers of Cu-in-concentrate. The mine, located in the central interior of British Columbia, is owned (97.5% interest) and operated by Teck Resources Ltd. In 2011, HVC produced about 210 million lbs. of Cu and 8 million lbs. of Mo. HVC’s Mill Modernization Project (MOP), which was budgeted for $475 M, is currently under intensive construction and is scheduled for commissioning in Q1 2014. The following description was valid at the time of writing this paper.The operation has been expanded a number of times since the startup of the original Lornex mill in 1972. The plant started up with two 9.75 m (32 foot) diameter primary SAG mills. It was expanded in 1981 with the addition of a 10.36 m (34 foot) diameter SAG mill. In 1988, the Highmont concentrator grinding mills and flotation section were moved and attached to the Lornex mill site. This added two10.36 m (34 foot) diameter AG primary mills to the Highland mill. This brought the total number of primary mills to five referred to as Line A, B, C, D and E: three SAG mills (A, B and C) each with two ball mills in parallel and two AG mills (D and E) each with one ball mill. Each AG mill line is equipped with one short head pebble crusher. Ball mill circuits are classified using 8 clusters of ten Linatex 762 mm cyclones to reach a target P80 330 micron (equivalent 43% +100 mesh), before the cyclone overflow product advances to the bulk flotation circuit."

Jan 1, 2013

By Paul Hughes

This paper describes a focus of work presently being conducted at the Rock Mechanics Research Group at the University of British Columbia. The underhand method under consolidated fill ensures a high recovery under an engineered back that is comprised of cemented rock fill and/or cemented paste fill. This method of mining has been employed successfully in mines throughout North America as a method of mitigating exposure to the operator having to work under a seismically active ?back?. This paper reviews design methodology in the placement and analysis of sill mats with reference to site observation coupled with on going numerical and analytically derived solutions.

Jan 1, 2006

By Charles E. Whieldon

Because of the importance of recovering more oil from known petroleum reserves, increased emphasis has been placed on the application of secondary-recovery methods. It is hoped that these reports will stimulate interest in improved waterflooding techniques, thereby discouraging premature abandonment of oil leases. Previously published reports3 4 5/ have described the results of water-flooding in Roane, Pleasants, and Wetzel Counties, W. Va. (fig. 1). This report describes the South Penn Oil Co. Yawkey waterflood property, Berea sand, Griffithsville oilfield, Duval District, Lincoln County, W. Va. (fig. 2).

Jan 1, 1961

By J. Chlopas, D. J. Barratt, M. V. Sharp

"This paper describes the modifications made to the Fox Mine copper concentrate bin in order to obtain a continuous flow condition. The design of these modifications is based on test results obtained on Fox Mine concentrate using the flow factor testing machine in the research facilities of Cominco at Trail, B.C.The original design consisted of a cylindrical steel bin on a concrete slab with two slot-discharge openings. Based on predictions of the maximum mass flow hopper angle for conical and wedge shaped hoppers for the concentrate on various potential bin lining materials, Ultra-High Molecular Weight (UHMW) Polymer was selected as a liner.Using the recommended angles for conical and wedge shaped hoppers, the profile of the bin base was changed to suit the existing slot openings.The initial method of fastening the liner resulted in failure of the connections. Subsequent modification to the zinc concentrate bin fastener system proved satisfactory and it has now been in operation for over one year without any separation of the lining material.Utilization of flow testing procedures on concentrate samples has demonstrated that proper design of storage bins or hoppers to achieve continuous flow can be incorporated into the design of new plants."

Jan 1, 1978

By T. C. Cheng, G. P. Demopoulos

It is the object of this paper to discuss various options for improving the hematite process in terms of increased throughput hence lower capital cost and production of saleable quality hematite. With reference to increasing the throughput of the process, it has now been determined via the analysis of Akita Zinc Co's continuous industrial autoclave performance data that the process kinetics is limited by the rate of the hydrolytic precipitation reaction. By correlating the hydrolytic precipitation rate to supersaturation ratio, it is shown that accelerated kinetics can be achieved via the following measures: (1) in-situ neutralization with addition of zinc calcine; (2) elevation of temperature; and (3) dilution of feed; of which, the first one was retained for further evaluation. According to presented estimates, addition of calcine, amounting to only 2.6% of the total zinc calcine processed, can allow for shortening the retention time by at least 50%. Such drastic shortening of retention time may be either used to increase the throughput of a given autoclave circuit or alternatively to release autoclave capacity for clean hematite production. Hydrothermal treatment of the crude hematite product proved effective in producing clean hematite as according to laboratory tests, hence allowing the sulphur content of hematite to be reduced from around 4% to less than 1%. A conceptual flowsheet incorporating in-situ neutralization for accelerated kinetics with hydrothermal upgrading of crude hematite without sacrificing production capacity and with minimum upset of the plant's water balance is described.

Jan 1, 2004

By C. Bazin

The separation of rare earth elements is a complex process that is industrially carried out using liquid/liquid extraction. Detailed flow sheets of solvent extraction plants for the separation of rare earth elements are rarely available in the literature which limits the opportunity to teach and test the application of data reconciliation, process optimization and control to these types of plants. The basis of a simulator for a rare earth elements separation plant is described in this paper. The simulator is used to adjust the organic phase and stripping acid flow rate in a separation circuit of heavy rare earth elements from light one?s.

Feb 27, 2013

By Olli Aulio, Outokumpu Oy

"GENERALThe Outokumpu Company is today an important European producer of metals from its own mines: copper nickel cobalt, ferro chrome and zinc being the main products. In 1972 about 4 million tons of ore was hoisted from eleven mines.Outokumpu Oy has gained experiences on the various aspects of on line computer control since 1968. This knowledge has been combined to develop a standard computer control package for concentrator control. Before the development of computer control package was started Outokumpu Oy had three large computer control systems. The first system was at the Pyhasalmi Concentrator, thee second at the LokkolaPlant, and the installation of the third system at the Vuonos Concentrator was just started.The characteristics of general computer software packages - both control and executive ones - were thus well-known as well as the practical usage of control theory. Furthermore Outokumpu had developed the Courier analyzer which included a so-called minicomputer. This project had given experience both 1n totally self made real tire executives and in computer hardware and peripheral d=vices. The instrumentation of the Outokumpu concentrators was designed and installed traditionally by the engineers of Outokumpu themselves."

Jan 1, 1973

Removal of Arsenic in Enargite from Copper Ores by Flotation and Leaching in NaHS Media

Sep 13, 2010

By P. Walford, C. Mealin, D. Good

"The geology of the Ore Fault Ni-Cu deposit has been reinterpreted in the light of recent studies of the geology of the Neoarchean Bird River Sill Complex and the occurrence of economic Ni-Cu and Zn-Cu-Ag mineralization. The Ni-Cu sulfides are hosted by the lower of two parallel NNW-trending and moderately W-dipping mafic-ultramafic intrusions related to the Bird River Sill Complex. The bod¬ies intruded a bimodal volcanic suite consisting of weakly deformed mafic flows and felsic pyroclastic rocks. The mafic volcanic rocks are geochemically related to the MORB-type rocks of the Lamprey Falls Formation, and the felsic volcanic rocks are related to arc-type rocks of the Peterson Creek Formation. The original pyroxene- and olivine-dominated mineralogy of the sills has been replaced by variable ser¬pentine-amphibole-talc-carbonate assemblages.The Ni-Cu sulfide assemblage exhibits textures and geochemical signatures typical of orthomagmatic sulfide mineralization. The sulfide minerals are associated with cumulate layers of magnetic ferrochromite that range in thickness from a few to tens of centimeters. A later event of Zn-Cu-Ag sulfide mineralization associated with quartz veining and garnet-chlorite alteration along a fault that strikes north, dips vertically, and cuts all rock types. The mineralized fault is cut by the NE-trending Peterson Creek shear zone. Where the Ni-Cu and Zn-Cu-Ag mineralized zones intersect, remnant magmatic features such as amphibolite or cumulate ferrochromite bands occur within quartz veins or local chlorite alteration. The mixed zones contain a very unusual polymetallic assemblage of Ni, Cu, Zn, Ag, and platinum group elements (PGE)."

Jan 1, 2009

By N van Aarde, B A. Moore, S van der Merwe

Frequently materials handling operations are compromised by transfer chute problems ranging from high wear rates, blockages and ineffective loading of the downstream conveyor. This paper will present the design flow implemented to overcome problems in two case studies utilising discrete element modelling incorporating material characterisation.Material testing is relevant in achieving a valid discrete element method (DEM) simulation model and subsequently a valuable design tool for transfer chute assessment and design. It is well recognised that in the current growth and demand for mineral resources, leading to ever increasing conveyor capacities associated with export terminals and mineral processing facilities that transfer chutes are a key focus point. The successful performance of the transfer chute is also dependent on operating with a ærobust rangeÆ of material flowability and handling characteristics. This requirement is crucial in accommodating mineral ores from developing resources, which are often more friable and stickier than in past decades.This paper will include details of chute installations associated with iron ore and coking coal, from the DEM simulations through to the performance of the installed and commissioned plant.CITATION:Moore, B A, van der Merwe, S and van Aarde, N, 2013. Implementation of advanced transfer chute designs, in Proceedings Iron Ore 2013 , pp 445-450 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 12, 2013

By Mark Rybak

On Aug. 31, 2006, Tropical Storm Ernesto hit the city of Richmond, VA. The Battery Park area was hit particularly hard, as flooding forced an evacuation of the area. A large sinkhole collapsed a sewer line in the Battery Park area, blocking the pipe and causing more serious flooding. This article describes the fast track design, bidding and construction of an emergency tunnel to bypass the collapsed sewer. Innovative value engineering, tunneling and shaft-sinking methods and final lining design all contributed to the success of this project. The storm inundated Richmond, VA with up to 305 mm (12 in.) of rain that, in some areas, caused widespread flooding and damage. One of the hardest hit areas of Richmond was Battery Park. A major trunk sewer in the Battery Park area collapsed and caused local combined sewer and stormwater flooding. The collapsed sewer was a 2.4-m x 76-mm (8-ft- x 3-in.-) wide by 2.7-m- x 152-mm- (9-ft- x 6 in.-) high arch sewer that was constructed in the 1920s and later filled over with municipal solid waste and a soil fill cap to cur-rent elevations. A sinkhole was created in the area of collapse approximately 18 m (60 ft ) deep and 31 m (100 ft) in diameter. This caused the existing arch sewer to become blocked. As a result of this blockage, contaminated floodwaters reached depths in low-lying areas in excess of 8 m (25 ft).

Jan 1, 2008

By D. K. Ingram, P. Jurovcik

The National Institute for Occupational Safety and Health (NIOSH) identified hearing loss as the most common job-related disease in the United States in its 1996 National Occupational Research Agenda. Previous studies by NIOSH have shown that operators of surface drill rigs without cabs are commonly exposed to A-weighted sound levels exceeding 90 dB. During hammer-drilling, A-weighted sound levels exceeding 100 dB were recorded at the operator station. NIOSH collaborated with a local drilling company to design and install a partial cab between the operator and the drill steel in an effort to reduce the sound level at the operator station. Sound level measurements in the field show the partial cab reduces the A-weighted sound level by 5 to 9 dB at the operator’s left ear and 2 to 5 dB at the operator’s right ear while hammer-drilling. This paper briefly discusses the preliminary design of a cab and the testing of materials for construction of the prototype. An explanation of the ideas behind the prototype design and fabrication are covered. Finally, the field test method and results are discussed in detail.1

Elongates are commonly used as stope support in South African gold and platinum mines. To evaluate the effect of the inherent strength, stiffness and yield variability associated with elongates, a statistical method is presented which addresses and quantifies the support performance at various levels of certainty. The analysis, which is based on a normal distribution, makes use of force-deformation curves determined from multiple laboratory compression tests on the same support type. The applicability of the method is illustrated making use of actual performance capabilities of various types of elongates. In order to ensure a high probability that support units installed underground exceed the standard support performance curve established by means of laboratory tests, the statistical mean of a suite of tests based on the same support type is downgraded. The ?correction factor? is a function of the mean and standard deviation of the test data, as well as the sample size of units deemed to control the local rock mass stability. It is shown that downgraded performance curves based on a high probability (90 to 95percent) of support units exceeding this performance level are suitable to ensure that the design of support systems will in variably meet the design criteria. In the highly discontinuous hangingwall rock mass typically associated with intermediate- and deep-level mining operations, the interaction between adjacent support units is comparatively limited (at the support spacings commonly used). Therefore, the appropriate sample size (n) of the support units controlling the local rock mass stability should be n= 1. In shallow mining conditions, sample sizes of up to n=5 may be warranted, depending on the spacing of joints and other discontinuities in the hangingwall.

Jan 1, 2001

By K. Sugawara, Y. Hirakawa, A. Sato

The rock mass properties such as deformability and permeability are highly dependent on the existence of cracks. The Ratio of Crack Opening Dependency (RCOD) was proposed as a new index to evaluate the deformability of infinite jointed rock mass. The RCOD is defined as the ratio of total amount of crack opening and the total deformation of jointed rock mass. The theoretical relation between the RCOD and the effective compliance of jointed rock mass is discussed and confirmed through two-dimensional numerical analysis by the SC-DDM, together with the applicability to the rock engineering. Les propriétés de masse rocheuse telles que la déformabilité et la perméabilité sont très dépendantes de l'existence de fissures. Le rapport de dépendance d'ouverture des fissures a été proposé comme un nouvel index d'évaluation de la déformabilité de masse rocheuse à assemblage infini. Le rapport de dépendance d'ouverture des fissures est défini comme étant le pourcentage de quantité totale d'ouverture des fissures et de déformation totale de la masse rocheuse assemblée. Le rapport théorique entre le rapport de dépendance d'ouverture des fissures et la compliance efficace de masse rocheuse assemblée sont traités et confirmés au travers d'une analyse numérique à deux dimensions par SC-DDM en même temps que l'applicabilité à l'ingénierie des roches. Die Felsmasseneigenschaften wie Verformbarkeit und Durchlässigkeit sind hochgradig abhängig von dem Vorhandensein von Rissen. Das Verhältnis der Riss-Öffnungsabhängigkeit (RCOD) wurde als neuer Index der Verformbargkeit von infinit zerklüfteter Felsmasse vorgeschlagen. Der RCOD wird als Verhältnis der Gesamtmenge der Rissöffnungen und der Gesamtverformung der zerklüfteten Felsmasse definiert. Die theoretische Beziehung zwischen RCOD und der effektiven Verformbarkeit von zerklüfteter Felsmasse wird diskutiert und durch zweidimensionale numerische Analyse mit SC-DDM bestätigt, zusammen mit der Anwendbarkeit auf Bergbautechnik.

Jan 1, 2003

By Frank E. Williams

This Bureau of Mines report describes 147 known fluorspar deposits in New Mexico and briefly mentions 54 miscellaneous occurrences for which little or no information was obtained. Most miscellaneous occurrences are minor and too poorly exposed to be considered more than prospects. History and production of fluorspar in New Mexico, type of deposition, mineralogy, uses, and grade specifications are discussed. Total mine production of fluorspar in New Mexico is nearly 641,000 tons of various grades of crude ore and hand-sorted material. Fluorspar deposits occur in 13 of the state's 32 counties. Grant, Valencia, and Luna Counties account for 86.4 percent of the total production. During the investigation, 141 deposits were visited. A total of 72 character samples was collected for assay, and 3 larger samples were collected for bench-scale metallurgical tests. Results of these metallurgical tests indicate that an acid-grade product can be obtained with 95 percent recovery of the CaF2 content of the crude ore.

Jan 1, 1966

By Natalia Konstantinova, Georgy Novikov, Pavel Rekant, Goergy Cherkashov, Olga Bogdanova

The economic interest of oceanic ferromanganese crusts and nodules is determined by high grades of major, rare and earth rare elements in these types of marine minerals [1]. Modern oceanic ferromanganese deposits have a global distribution with the largest fields in the Pacific Ocean. The Arctic Ocean still remains a poorly explored region. The first ferromanganese deposits from the deep part of the Arctic Ocean were recovered almost at the same time in 2012 both in US and Russian cruises to the Chukchi Borderland (1) and Mendeleev Ridge (2). Preliminary results of mineral deposits from the first area were reported at UMI-2012 by James Hein et al. [2]. We present here the data of ferromanganese deposits from the Mendeleev Ridge.

Sep 1, 2014

By Frank E. Williams

This Bureau of Mines report describes 147 known fluorspar deposits in New Mexico and briefly mentions 54 miscellaneous occurrences for which little or no information was obtained. Most miscellaneous occurrences are minor and too poorly exposed to be considered more than prospects. History and production of fluorspar in New Mexico, type of deposition, mineralogy, uses, and grade specifications are discussed. Total mine production of fluorspar in New Mexico is nearly 641,000 tons of various grades of crude ore and hand-sorted material. Fluorspar deposits occur in 13 of the State's 32 counties. Grant, Valencia, and Luna Counties account for 86.4 percent of the total production. During the investigation, 141 deposits were visited. A total of 72 character samples was collected for assay, and 3 larger samples were collected for bench-scale metallurgical tests. Results of these metallurgical tests indicate that an acid-grade product can be obtained with 95 percent recovery of the CaF2 content of the crude ore.

Jan 1, 1966