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By Clark Woodland, William E. Stanley

Mining companies have been required to enter a "new era of management" in the 1980's as they strive to become more efficient in an increasingly competitive market place. One response for many companies has been to modify their mine accounting systems to make them more effective for cost control and decision-making. This paper discusses some of the major issues in developing and implementing a standard costing system as part of improved management reporting and cost control procedures. It describes the key features and benefits of a computerized standard costing system with particular emphasis on budget-setting and variance analysis. It also identifies important factors to be considered in order to achieve successful project planning and Implementation.

Jan 1, 1987

By Jin Yu, Fang-Qiu Zu, Yun Xi, Li-Na Mao

"According to the behaviors of resistivity-temperature of Cu-Sb70 melt, which suggests a partly reversible temperature-induced liquid structure transitions (LST) could occur in this alloy, in this paper, we investigated the dependence of solidification on the liquid state. Both resistivity and temperature were measured to track solidification process. The results show that the nucleating undercooling of the melt which experienced the LST increased and the solidified time decreased. Meanwhile, the solidified microstructures refined evidently, with the microscopic pattern of primary phase changes from disordered pillarlike dendrites into homotaxic ones. Moreover, it is verified that the microstructures would be different if the reversible part of the LST was restrained. The new phenomena and results reflected in this paper suggest that grasping the rules of melt structure change with temperature before material processing will give help for controlling the solidification more effectively and finally resulting in more ideal microstructures.IntroductionThe structure and quality of liquid alloys have a direct and important influence on the structure, performance and quality of the solidified ones. In recent years with in-depth study of liquid structure, researchers have found that some liquid structure transitions (LST) could occur on dependence of the temperature or pressure [1-5]. And the article [6] reported that a pressure-induced reversible LST was found in liquid triphenyl phosphite, which further confirmed the authenticity of the existence of the LST. Furthermore, in our earlier studies of Sn-based melts using resistivity method, some abnormal structure changes induced by temperature have been found at hundreds of degrees above liqiudus, and these LSTs are partly reversible[7]. This phenomenon has been discussed and it is suggested that the reversible LST in Sn-based melts are related to the short-range ordering (SRO) structures of Sn, which are tetrahedron structure with covalent bonding. However, does this reversible LST exist in other melts too?"

Jan 1, 2012

By W. S. Fyfe

The future environment of our planet, with the concept of sustainable development, has moved to centre stage of all future plans for development. This global view is new. It presents great opportunities and challenges for the Earth Sciences. We have the tools to describe our environment on all scales - planetary to molecular levels. We must respond to this great demand by world society.

Jan 1, 1990

By J. Betzhold

Knowing more about an orebody makes it easier to exploit it profitably. Many orebodies are made up of different rock types, alteration zones or mineralogical ensembles: oxides versus sulphides or facies with different metallurgical properties for example. Being able to model the spatial layout of these different facies is vital to good mine planning and management. Kriging cannot be used to generate numerical models of orebodies with complex geometric patterns because it gives too smooth an image. Over-smoothing has the meaning of changing the natural selectivity. Conditional simulations are required to do this kind of model respecting the natural variability: honouring the natural selectivity, dilution and ore loss. Standard geostatistical simulations cannot duplicate many of the complex spatial relationships seen in the earth sciences, such as differently orientated facies, sets of conjugate veins or ore types where certain facies cannot touch. After a presentation of the case study, it will be shown why traditional methods for simulating indicators like the sequential indicator simulations, or the truncated gaussian method, cannot be used to simulate it. Plurigaussian simulations are then introduced and shown to be more powerful than the previous methods in their range of application. This is confirmed by the case study treated; a Chilean copper deposit, for which the plurigaussian simulations are seen to respect the different orientations of the individual facies as well as honouring the facies seen in drill holes, and respecting the proportion of each facies even if this varies in space (e.g. increases or decreases with depth). Key words: geostatistics, indicators, conditional simulation, plurigaussian method, copper variability.

Jan 1, 2000

The research, development and testing of a Blast Control Plug (U.S. Pat. #4,754,705) funded by the U.S. Department of Energy is described. The plug's function is to improve blasting efficiency through the enhancement of stemming effectiveness and thereby reduce drilling and blasting costs. The plug comprises a solid unit placed in the blast hole within the stemming column above the explosive. It is designed for use with back filled drill cuttings or any other suitable material The research and development program comprised the testing of the plug in small diameter holes in competent rock for both bench and crater blasting configurations and full scale field trials in multiple hole and row blasts using blast holes of from 76 to 387 mm in diameter. Test measurements included stemming displacement and velocity, face movement and extent, peak air over pressure and ground surface peak particle velocity. Data acquisition equipment included a Spin Physics SP2000 high speed video motion analysis system, and acoustic and seismic monitoring units. Substantial reductions in stemming ejection velocity or ejection elimination were achieved whilst reducing stemming length by up to 35% over conventional practice. Peak air blast pressures were also reduced by between 8 and 25 dB. A strong inverse relationship between rock face movement and stemming ejection velocity was found. The implications of the importance of stemming effectiveness in blasting and computer blast simulation is also addressed.

Jan 1, 1990

El siguiente estudio describe la relación del proceso de electrificación de empresas eléctricas asociadas (Lima, Arequipa), con la minería y la industria azucarera. De los tres campos mencionados, es la minería, la actividad que ha contribuido mayormente al proceso de desarrollo eléctrico (30%), y con el 50% en su aprovechamiento de potencial hidroeléctrico. Asimismo, las necesidades de electricidad para la producción de cobre, zinc y plomo son de 1, 800, 4600 y 450 Kw. -hr. por tonelada de mineral en las minerías del país, Cerro de Pasco y Junin, revelando un espacio de reserva de 600, 000 kw hasta el año de 1975. En este sentido, el proyecto hidroeléctrico del Mantaro, se considera como el sistema eléctrico más idóneo dentro del Plan de Electrificación Nacional, cuya producción alcanza 513,000 Kw. para la ciudad de Lima -en tanto fines de prestación de servicios púlblicos-, y se interconecta posteriormente con la costa norte del Perú. En consecuencia, la ejecución de esta primera etapa del Mantaro, permite alimentar al yacimiento minero de Cerro de Pasco, y al 90% de las minas de los departamentos de Junín, Pasco y Lima.

Jul 20, 1959

By D. E. Larson

The U.S. Bureau of Mines has developed a image analysis methodology to correlate the energy consumed during the grinding of an ore to the mineral liberation achieved. Energy consumption values are obtained using a laboratory-scale ball mill equipped with a torque sensor, and an automated image analyzer is used to determine the liberation present in ground products. By combining liberation information with energy consumption data an appraisal can be made of the energy required to liberate the mineral(s) of interest. Results of tests performed on a complex sulfide material determined the effects of grind duration on the liberation achieved and the energy efficiency.

Jan 1, 1995

By Graham Bright

THE rapid increase in reliability, the low cost f operation, the ready application of safety devices, and the growing availability of central-station power have made the question of installing a hoist of the electric type no longer debatable. Where adequate electric power is available, there are few cases where it would be advisable to install a steam or air hoist. The type of electrical equipment depends largely on the nature of the power supply, its capacity, and the form of the power contract under which power is purchased. In a large majority of cases, the available electric power is alternating current, three phase, 60 cycles. There is, however, considerable 25-cycle power in use; and in a few instances constant voltage direct current is the only power available for a small or an occasional medium-size hoist. Where a new hoist is to be installed, the designer of the mechanical parts can readily take care of the maximum stresses likely to be imposed by the' motor. Where the hoist is already installed and operated by steam or air and it is desired to substitute an electric motor for the engine, a careful check should be made to determine the advisability of using the old mechanical parts. In most cases it is better to install a complete new hoist than to attempt to use old mechanical parts. A steam engine has a definite maximum torque, which the hoist has been designed to withstand, while a motor may be able to deliver momentary torques beyond the strength of the mechanical parts of the hoist. The selection of the proper type of electrical equipment can only be made after complete information is obtained and certain calculations made to determine the capacities required. There are several methods used in making hoist calculations, but no matter what method is utilized a fair degree of familiarity with hoists and hoisting conditions is necessary before an intelligent analysis and proper selection can be made.

Jan 9, 1921

Molybdenum was first discovered on the Continental Divide in Colorado in 19 11; and in 1918 two companies, one of which was the Climax Molybdenum 250 stpd operation, were producing. In 1919 both mines were shut down, but in 1924 the Climax mine reopened and has been producing ever since. Over the years mine production has been increased until today the mill capacity is 48,000 stpd (43,500 mtpd). From 1935 to 1973 all ore was mined underground by block caving with scraper slushing. Since 1973 ore production has been supplemented by open pit mining. As demand for molybdenum increased, upper levels of the mine became worked-out and new lower levels were opened. In late 1972 production began on the 600 level with the mined ore being primary and secondary crushed in the new No. 4 crushing station. Ore is hauled to the primary in 10 st (9. 1 mt) capacity Granby side-dump cars. The trains, carrying 200 st (181 mt), pass throug.h a dump block and discharge directly into a 54 in. by 84 in. Traylor TC gyratory crusher set at an 8 in. (203 mm) open side setting. Since the ore has already been broken to a size which will pass the finger raises in the mining areas, there are only rare oversize boulders to block the crusher opening. Selection of the crusher was based more on its capacity than its receiving opening, as is often the case with gyratories used in open pit operations. Nominal and maximum capacities for this unit are 1250 and 1800 stph (1 135 and 1635 mtph). The ore is often wet and sticky, so a mechanical car cleaning device is utilized. Under the crusher is a 300 st (270 mt) ore pocket equipped with a 60 in. (1.52 m) wide inclined conveyor which delivers the ore to a 2,000 st (1800 mt) surge bin. Near the head pulley of this conveyor is a wood picking station whe re tramp wood and steel are put into cars for removal. Two more apron feeders remove the primary crushed ore from the surge bin, and impact belts and conveyor belts transport the ore to the crushing station for screening ahead of two 7 ft (2. 13 m) standard crushers. Secondary crushed ore is then conveyed to the surface for tertiary crushing. The entire underground crushing room containing the primary, two secondaries, screens and related equipment is serviced by a 100 st (90 mt) crane with a smaller capacity fast hook. A control room is situated so the operator can observe all the crushing operations. Rotoclone collectors remove dust from the entire operation (including the fumes from the zinc pots) and discharge it to the final product belt. The Rotoclones are vented through drifts and raises to the surface. Shop facilities, electrical gear, and lubrication equipment are located

Jan 1, 1978

By B. M. O'Harra

The residues resulting from the retort distillation of zinc ores have from 40 to 75 per cent of the weight of the original ore and contain from 5 to 15 per cent zinc . A rough estimate indicates that approximately 450,000 tons of residues are produced annually in the United States , containing about 36,000 tons of zinc . Besides the current production of residues there are at many smelter sites large accumulations from past operations which are available for treatment if this can be done profitably . In addition to their zinc content the residues contain much unconsumed coal , which has been carbonized during the distillation process , and those from most western ores also contain lead and silver . In this paper is summarized the information obtained in a survey , recently made by the Bureau of Mines , in cooperation with the Missouri School of Mines and Metallurgy , of processes which are in use or which have been suggested for the treatment of retort residues . The complete report of the survey is to be published as a Technical Paper of the Bureau of Mines .

Apr 1, 1923

By George Hope, Edward H. Smith

In late 1989, LAC Minerals purchased 65% of Bond International Gold and as a result became controlling shareholder of the El Indio Mine through Bond and San Jose. El Indio is a world class, complex sulphide gold deposit located in the hydrothermal alteration belt of the Andes mountains in the 4th Region of Chile. The mine is located in the high Andes about 185 km east of La Serena at an elevation of 4000 meters. The 1450 workers at El Indio live in the mine camp at 3200 m and on days off are bussed to La Serena. The El Indio mine was started in 1979 by St. Joe Minerals Corp., bought by Bond in 1987 and subsequently by LAC in 1989. The mine has produced 2.7 million oz. of gold, 9. 5 million oz. of silver and 170,000 t of copper since start of operation. The mill is currently operating at a rate of 2850 t/d and producing a copper/gold concentrate which is roasted to produce a copper/gold calcine and high quality, saleable crude As203• A small proportion of the precious metals are also produced as bullion from the leach circuit. Total production during 1989 was 224,197 ounces of gold, 1,309,342 ounces of silver and 26,968 tonnes of copper. The average cash cost of production for the period was U.S. $96 per ounce of gold, net of by-product credits. The average realized price was $5.30 per ounce of silver and $1.14 per pound of copper.

Jan 1, 1990

By K. M. Reim

Planning the development of the Quartz Hill molybdenum open pit mine in Southeast Alaska required a number of special considerations. Located in mountainous glaciated terrain, about 3.8 m (150 in.) of annual precipitation (with annual snowfall over 10.2 m (400 :in.) was a primary consideration. Mine planning included muskeg and snow removal, avalanche control, clearing timber, water quality control, dust control, seismicity, mine schedule, work force and reclamation. Quartz Hill is in an environmentally sensitive area which has required extensive environmental baseline data collection, four Environmental Impact statements (EIS) and a large number of permits.

Jan 1, 1988

By K Higuchi, K Saito, O Ishiyama

Iron ore in Australia is predicted to increase in its phosphorus content in the near future, which is detrimental to properties of steel product. Steelmakers are concerned by the content of phosphorus in iron ore will exceed limits for steelmaking and increase the converter slag ratio to molten steel, which will finally lead to a decline in competitiveness in high-grade steel production. In this paper, fundamental development of a dephosphorisation technique by reduction gasification is considered. Basic reduction examination was carried out using Australian and a synthetic model iron ore sample with phosphorus compound reagent, varying reaction time and composition of substances to find out suitable process condition for dephosphorisation. With successful lowering of phosphorus concentrations by gasification reduction of the iron ores, dephosphorisation was assumed and further elucidation works were carried out. More than 10 mass per cent of dephosphorisation ratio is obtained from Australian iron ore through batch-type 25 g furnace experiment using hydrogen as a part of reducible mixed gas. Lowering of phosphorus content occurred preferentially either in wustite or in another reducing zones, suggesting a relationship between reducing conditions to efficient dephosphorisation of iron ores. Another result of the fundamental experiment using a model sample with reagent is different dephosphorisation occurred with different reagents contributing to with unified reduction model for phosphorus, providing positive possibility for comparative evaluation, even if new morphologies of phosphorus in iron ore are clarified in future. According to these approaches, it is important to reduce iron ore efficiently and to avoid gasified phosphorus retaining and reattaching to adjacent iron ore particle at the same time. A kiln-type furnace is suggested to overcome previous technical issue, and additional experiments using larger rotating furnace were carried out for verification.

Sep 18, 2023

By B. Woyski

MANY writers, in discussing defects caused by oxidation and gassing of bronzes and red brasses advocate substantially the same cure for both. But from its nature, oxidation cannot take place if there is an excess of fuel in the furnace, while the gases absorbed by some alloys are products of incomplete combustion of the fuel. Hence the metal can be either oxidized or gassed, but it is doubtful whether these actions can take place simultaneously. Oxidation can be easily overcome by the use of deoxidizers or it may be avoided by protecting the molten metal with suitable fluxes. Absorption of gases is more difficult to overcome. The regulation of the air and fuel, so as to produce complete combustion, and the protection of the bath by mineral fluxes are the most important factors. Gas expulsion, resulting in gas holes, porosity, unsoundness, and swollen or cauliflower-headed risers, is said to have several causes. One writer' lists the most common causes in the order of their importance, as follows: Superheated metal, dirty or slaggy furnace conditions, using metals low in quality or those previously subjected to bad melting practice, poor grade of fuel, use of newly lined or damp ladles, indiscriminate mixing of scrap or illogical combinations of metal. Superheating the metal usually occurs when the heat is ready to be poured but for some reason must be held in the furnace. In this case, a careful furnace tender tries to avoid overheating the metal by keeping a mild fire; that is, a reducing fire which, unfortunately, results in gassing the metal. A dirty, slaggy furnace may result in gassing the metal by retarding the heating and prolonging the time necessary to bring the metal to the proper temperature, thereby increasing the chances of gassing in uncertain furnace atmosphere.

Jan 5, 1922

By J. A. Morgan, P. M. Dimmell

Abstract - The Aubry pegmatites are located on the Seymour Lake property, 15 km north of Lake Nipigon in northwestern Ontario. The property lies within the Caribou Lake-Marshall Lake greenstone belt along the English River-Wabigoon subprovince boundary of the Superior province of the Canadian Shield. The property was optioned in March 2001 by Linear Resources (now Linear Gold Corp.), who carried out gridding, prospecting, geological mapping, soil and lithogeochemical sampling, trenching, channel sampling, and a total of 1,866 m of diamond drilling in 32 holes. The Aubry pegmatites are classified by Breaks et al. (2003) as complex type, spodumene-subtype, lithium-cesium-tantalum pegmatites (Cerný, 1989). These pegmatites generally form under high-pressure-low-temperature conditions, display complex internal zoning, have relatively low Nb/Ta ratios in the ore-forming assemblages, and contain significantly elevated tantalum values (Cerný, 1989). Other examples of spodumene-subtype pegmatites include the formerly producing Hugo pegmatite in South Dakota, and the currently producing Greenbushes pegmatite in Australia. The Aubry pegmatites occur as an undulating system of stacked sheets that dip moderately to steeply eastward over a 1-km strike length. The main portion of the North Aubry pegmatite ranges in true thickness from 10 to 28 m over a strike length of 125 m, whereas the thickest portion of the South Aubry has an estimated true thickness of 15 to 16 m over a minimum strike length of 95 m. The North Aubry pegmatite remains open downdip and along strike to the north, whereas the South Aubry pegmatite remains open downdip and along strike in both directions. The Aubry pegmatites are among the most highly evolved in Ontario, with the southern end of the North Aubry (trench 5/6 area) being the most highly fractionated (Breaks et al., 2002). Channel samples from the trench NA-5 area of the North Aubry pegmatite produced values up to 2.49 wt.% Ta2O5 over 4 m. Coarse manganotantalite crystals, up to 5 cm in diameter, from this trench contain up to 84.9 wt.% Ta2O5 (Breaks et al., 2002). Drill hole SL02-31 in the trench NA-6 area gave values of 0.046 wt.% Ta2O5 over 17.7 m, including 1 m @ 0.464 wt.% Ta2O5. Further exploration will focus on defining the grade of the North Aubry zone, extending and defining both known pegmatites, and identifying additional Ta-rich zones within them. Lithogeochemical and enzyme leach soil geochemical data suggest the presence of multiple undiscovered pegmatites on the property.

Jan 1, 2005

By WM. E. Mlligan

IN the last year, much information had become available as to the extent that zinc participated in the war effort. The importance of foreign zinc in this program had been indicated by Bateman (M&M April 1945) as of the order of 400,000 tons annually in zinc or contained zinc. Pehrson (M&M April 1945) reviewed the domestic ore-reserve situation with respect to most minerals and metals and showed the extent to which commercial zinc ores had become depleted in this country. This picture was further darkened by O.P.A. figures appearing in E.&M.J. July 1945 in which figures for total production during the three previous years were broken down into percentages produced under ceiling and various quota price categories. True, factors other than depleted ore reserves contributed to this picture. Among the more important of these, were shortage and high cost of labor, both skilled and unskilled, and the general difficulty and cost of maintaining adequate equipment and supplies. The cost of production in the Tri-State district was most affected.

Jan 1, 1946

Kidd Mine in Northern Ontario is now producing from Stage 1 of the Mine D expansion project ? mining between 2100 m and 2700 m below surface. Planning for Stage 2 of the Mine D project is already well advanced and will see the mine extended potentially to 3100 m below the surface. To ensure adequate ventilation is maintained at such depths, two large axial fans have been installed on the 6000 Level (1800 m below surface) as exhaust booster fans to operate in series with the surface exhaust fans. The Kidd Mine 6000 Level Booster Fans are a unique installation with unique and often unexpected challenges. These challenges have been met and attacked through the combined efforts of mine and fan manufacturer personnel with a common focus.

Jan 1, 2009

By Benjamin C. Greene, H. Beecher Charmbury

Water is a most remarkable substance, essential for life of all kinds. As well as needing water to survive, man has always used it for agriculture, transportation, recreation, and many other things. When our country was young and inhabited by few people, the streams, rivers, and lakes were able to provide all the clean water needed by man and take away all the wastes created. However, with our growing population and an ever-increasing demand for goods and services, the public, industry, and government at all levels have become acutely aware of the need to manage the nation's water resources more efficiently. Abundant energy from many sources has helped this nation to become the greatest industrial nation in the world. Coal has contributed a major portion of this energy, generating electricity, running railroads, and maintaining national security during wartime. The result has been the highest standard of living in the world and a time of widespread economic prosperity. The use of water in coal mining is somewhat different from its use in most industries. With the exception of water used in cleaning plants, for underground dust control, and for fire protection, most of the water en- countered in coal mining operations serves no useful purpose. In other words, it is an undesirable element and must be removed, otherwise it will interfere with operations, cause potential water quality problems, and may even stop operations by flooding. In the past, removing water from working areas of most mines was usually a fairly simple matter. Pumps with piping were installed at sumps or low spots in the mine and the water was pumped to the surface or to drainage control facilities constructed for the operation. Ditches were often used to collect and drain the water by gravity to the outside or to main sumps for pump discharge. In either case, the water was allowed to flow into the nearest stream or river. The concept of "water is water'' was generally accepted without too much concern for what was in

Jan 1, 1981

By Dave Ritchie

En el Perú existen 7 cable-carriles en funcionamiento, de los cuales la mayoría son bicables, cuyos baldes están suspendidos y son jalados por medio de un cable de tracción sobre un cable estacionario. En este aspecto, el objeto del estudio describe el empleo de los mismos en Cerro de Pasco Corporation, su historiografía, costos, procesos, instalaciones y el peso. Así, es menester conocer que dos de los más grandes bi-cablecarriles se encuentran en Mahr Tunnel de la Cerro de Paseo Corporation que conecta la mina de San Cristóbal con la Concentradora de Mahr Tunnel, mientras que el otro está en Quiruvilca, propiedad de la Northern Perú. También hay otros cablecarriles en Tamboraque, Atacocha, en las minas de San Luis y en la fundición de La Oroya. De otro lado, en 1864 se dispuso de parte de la Corporación, la instalación de un mono cablecarril para conectar la mina de Yauricocha con un lugar llamado Chaucha, el cual era el terminal de la línea del tren de Chaucha a Pachacayo. Siendo desde entonces, el único mono-cablecarril de la Cerro de Pasco Corporation, situado en Perú, mientras que los dos restantes pertenecen a la Reynolds Metal Co de Jamaica, y el otro a una mina canadiense, respectivamente. Asimismo esta cablecarril acarrea 48 toneladas de mineral por hora y permite ahorrar el costo de acarreo de madera por camión sobre los caminos de Chaucha a Yauricocha, aunque surgieron algunos defectos con el desprendimiento de los baldes transportadores. Finalmente el cablecarril de San Cristóbla a Mahr Tunnel

Jul 20, 1955

By Sudarshan Martins, Peter Radziszewski

"Tumbling mills are machine, operating in non-equilibrium, capable of applying forces on the ore contained within, causing the ore to break down. The action of the mill on the ore is very inefficient, producing a large quantity of heat. The inefficiencies of the mill drive the desire for improvement, spawning research and development activities. Given the non-equilibrium nature of the mill, the theory of Large Deviations is proposed as the framework that captures the state of the mill. The theory of Large Deviations allows for the determination of the rate function and the scaled cumulant generating function (SCGF), for systems in either equilibrium or non-equilibrium. Powerful connections can been made between familiar concepts of statistical physics and the concepts introduced by the theory of Large Deviations: entropy can be associated with the rate function; the scaled cumulant generating function with the free energy. It is shown that observables, compatible with Large Deviation theory, can be identified for the tumbling mill. Here, the time series of the energy associated with an element of the charge is such an observable. Furthermore, using some experimental data, it is shown that the time series of the energy can define a rate function, thereby describing the system within the Large Deviation framework. Finally, a discussion of the results is given, particularly how this theory can be further developed for tumbling mills."

Jan 1, 2014