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1. New publications International minerals/metals review - 1982. Washington D.C., McGraw-Hill, 1983.720 pp. U.S.$1l7. Mining subsidence engineering, by Helmut Kratzsch. New York, Springer, 1983.580 pp. U.S. $63,20. Papers presented at the 6th International Symposium on Jet Cutting Technology, Guildford, England: April 6-8, 1982, edited by H. S. Step hens and E. B. Davies. Cranfield (England), BHRA Fluid Engineering, 1982. £40. 2. Mintek reports Report M95 Modern applications of polarography and voltammetry to inorganic analysis. Report M96 The mathematical modelling of the reduction behaviour of chromite from the Upper Chromitite Layer of the Bushveld Complex. Report M113 The selective flotation of South African chromite. Conference on copper The International Conference 'Copper 83', to be held in London on 1st and 2nd November, 1983, will provide a valuable forum for all connected with the manufacture and use of copper. Underwater mining The 14th Underwater Mining Institute will be held in Madison, Wisconsin, on 7th and 8th November, 1983. Asian mining The Institution of Mining and Metallurgy, in conjunction with the Chamber of Mines of the Philippines, will hold an international conference, Asian Mining '84, in Manila, Philippines, from 6th to 8th November, 1984. Apcom '84 The Eighteenth International Symposium on the Application of Computers and Mathematics in the Minerals Industries will be held in London in the week 26th to 30th March, 1984. The Symposium is being Jet cutting Another Symposium on the very successful and popular series of international conferences on Jet Cutting Technology is being arranged by BHRA.

Jan 1, 1983

By James A. Mason

The State of California has instrumented numerous buildings, bridges, and dams throughout the state with earthquake recording devices. These accelerometers are strategically placed to measure the response of the structure to a specific seismic event. This comprehensive program enlightens the field of seismic engineering after each earthquake. The Office of Strong Motion Studies, California Strong Motion Instrumentation Program, a sub-branch of the Division of Mines and Geology, provides a professional service unequalled in the world. Within hours of a local earthquake, a preliminary report with the epicenter / hypocenter, structural damage, and time history records are available to all interested parties. The included partial report in the appendix, see section 5.1, is one of the reports that C.S.M.I.P. produced after the Loma Prieta Earthquake of October 17,1989. The diagram on the cover is even of interest. This is a small portion of San Francisco. The values on the diagram are the recorded maximum horizontal ground accelerations at that location in the city. For example, the acceleration at Yerba Buena Island was 0.06g. (The "g" refers to the acceleration of gravity. Thus, a 0.06g acceleration refers to the force, F=m*a, that the structure would experience. For this case, the force would be six percent, 6 % , of the mass of the structure.) Yet, directly on the other side of the Bay Bridge, at Treasure Island, the acceleration was 0.16g. Yerba Buena Island is a natural island composed of hard granular material. Whereas, Treasure Island is a man-made island of imported filled. Here one can see the absorption / transmission difference between hard material, which interact with short seismic wavelengths, and soft cohesive material, which interact with long seismic wavelengths.

Jan 1, 1993

By M. B. Standing, D. L. Katz

Equilibrium data are reported on the composition and densities of coexisting vapor and liquid phases as a function of Pressure and temperature for four hydrocarbon systems prepared from crude oil and natural gas. The data were observed over a range of pressures from 1000 to 8220 Ib. per sq. in. and at temperatures ranging from 35' to 250°F. The compositions of the hydrocarbon systems were such that the critical temperatures of the mixtures were lower than the range of the investigation. Under these conditions, it is shown that the composition of the systems has a marked effect upon both the absolute value of the equilibrium constants and the change of the constants with pressure for the several components comprising the system. From weight-balance considerations, it has been possible to construct the partial phase diagram of a mixture of a 49.9" A.P.I. crude oil and natural gas having a gas-oil ratio of 3660 cu. ft. per barrel. Descriptions of the apparatus used, the analytical procedure, the material used, and the equilibrium measurements are included. A knowledge of the physical behavior of naturally occurring hydrocarbon mixtures is fundamental to the treatment of many problems in the production, transportation and rehing of petroleum. The recent discoveries of pools having formation pressures up to 7500 lb. per sq. in. and higher, and the development of full-scale equipment to operate at pressures of 5000 lb. per sq. in. or more have greatly increased the need for knowledge of the composition, temperature, pressure and density relationships of coexisting vapor and liquid hydrocarbon phases. The following paper presents the results of investigations upon 22 mixtures of natural gas and crude oil of known com~o~itio~ that had been brought to equilibrium under controlled conditions of temperature and pressure. Data are presented upon the densities and compositions of the coexisting vapor and liquid phases for four different systems containing hydrocarbon material having boiling points from minus 2 5S°F. to well over I000 F. The data were observed Over a pressure range from Iooo Ib. per Sq. in to 8220 lb. Per sq. in. and a temperature range from 35' to 2 50°F. The accepted method of computing the physical relationship between two coexisting phases of a hydrocarbon mixture is by use of the "equilibrium constant" K as proposed by Souders, Selheimer, and Brown. definition,

Jan 1, 1944

By M. B. Standing, D. L. Katz

Equilibrium data are reported on the composition and densities of coexisting vapor and liquid phases as a function of Pressure and temperature for four hydrocarbon systems prepared from crude oil and natural gas. The data were observed over a range of pressures from 1000 to 8220 Ib. per sq. in. and at temperatures ranging from 35' to 250°F. The compositions of the hydrocarbon systems were such that the critical temperatures of the mixtures were lower than the range of the investigation. Under these conditions, it is shown that the composition of the systems has a marked effect upon both the absolute value of the equilibrium constants and the change of the constants with pressure for the several components comprising the system. From weight-balance considerations, it has been possible to construct the partial phase diagram of a mixture of a 49.9" A.P.I. crude oil and natural gas having a gas-oil ratio of 3660 cu. ft. per barrel. Descriptions of the apparatus used, the analytical procedure, the material used, and the equilibrium measurements are included. A knowledge of the physical behavior of naturally occurring hydrocarbon mixtures is fundamental to the treatment of many problems in the production, transportation and rehing of petroleum. The recent discoveries of pools having formation pressures up to 7500 lb. per sq. in. and higher, and the development of full-scale equipment to operate at pressures of 5000 lb. per sq. in. or more have greatly increased the need for knowledge of the composition, temperature, pressure and density relationships of coexisting vapor and liquid hydrocarbon phases. The following paper presents the results of investigations upon 22 mixtures of natural gas and crude oil of known com~o~itio~ that had been brought to equilibrium under controlled conditions of temperature and pressure. Data are presented upon the densities and compositions of the coexisting vapor and liquid phases for four different systems containing hydrocarbon material having boiling points from minus 2 5S°F. to well over I000 F. The data were observed Over a pressure range from Iooo Ib. per Sq. in to 8220 lb. Per sq. in. and a temperature range from 35' to 2 50°F. The accepted method of computing the physical relationship between two coexisting phases of a hydrocarbon mixture is by use of the "equilibrium constant" K as proposed by Souders, Selheimer, and Brown. definition,

Jan 1, 1944

The U.S. Bureau of Mines investigated CaF2-assisted H2SO4 leaching to extract Mn from domestic silicate manganese resources. A pyroxmangite ((Mn,Fe)Sio3) ore containing, in pct, 34 Mn, 23 Si, 3 Ca, and 1 Fe was leached at 90° C for 3 h in a solution containing, in g/L, 12 Mn, 140 H2SO4, 130 (NH4)2SO4, and 5 CaFz. Manganese extraction of 92 pct was achieved. Manganese of greater than 99 pct purity was prepared by electrolyzing the purified pregnant solution at a current density of 50 mA/cm2. The current efficiency was 65 pct.

Jan 1, 1991

By J F. Seale

The design of the settling pond for the Malvern Hills opencast coal project was based on a primary requirement to control runoff and sediment generated from the immediate 6 ha mine catchment, which included two seepages from old underground workings. The pond has been particularly effective in controlling turbidity in the outflow water, with the consent limit of 50 NTU being met on all but one occasion and normal levels of discharge less than 10 NTU. Water quality testing carried out at the time of consenting indicated that there were no acid-generation issues with the proposed mine site in dominant mudstone strata of the Broken River Formation, and that water from the old mine workings was near-neutral in terms of pH and well-buffered. However, it became apparent over the very dry summer of 2003 - 2004 that slaking of the exposed mudrocks in the mine batters was resulting in significant acidity generation, and outflow pH levels were well below the consent limit of 6.5 during and following periods of rainfall. Although these acidity problems have been remediated in the short-term by the use of lime products, it is clear that a programme of lithotype characterisation for AMD should have been undertaken and this has now been implemented. Design of long-term acid drainage control measures is being carried out, and will probably be based around the use of hydrated lime for pH control with enhancement of natural wetlands.

Jan 1, 2004

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, whereas 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 fluidized bed technology in several different reactor types for a multitude of process applications. The versatility of the fluidized 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 Bern Klein, Randy Blaskovich, Reem Roufail

"Morphology is a tool that is rarely used for mineral breakage mechanism evaluation. Ground particles are typically assessed for their size distribution. They are also visually analyzed using image analysis. However, image analysis is not a comprehensive evaluation of the particle surface texture. It evaluates particle’s size parameters such as area, diameter, and perimeter amongst other features. On the other hand, morphology analysis takes the particle assessment to another level of detail. Morphology analysis evaluates particles’ roundness, elongation and angularity that would indicate the degree of roughness of the particle. According to Roufail and Klein (2009), rougher surfaces are generated due to breakage along grain boundaries – intergranular breakage. Mill operation, particularly mill speed, dictates the dynamics in the mill. Stirred mills are known to break the particles via abrasion under standard operation. However, if the dynamics of the grinding media in the mill are changed, the particles could be more exposed to impact and compression loading that would lead to a different mode of breakage.In this paper, the effect of material properties and mill operating conditions on particle morphology will be studied. Hard non-sulfide versus soft sulfide minerals are compared, namely quartz and galena, respectively. Extreme mill speeds are tested covering the range of 1000 to 2000 rpm for a 4-litre Netzsch (ISA) mill. In addition to particle size distribution, micro-analysis is executed in the form of morphological analysis using a tested manual roughness point counting technique.INTRODUCTIONGrinding in general and stirred milling in particular are processes that are used to break particles to liberate metal-bearing minerals for further separation downstream. The energy required to achieve the target particle size versus maximum possible liberation has been studied intensively and it is usually the breaking point for the grinding system chosen in a process flowsheet. Operating conditions are dictated by the energy consumption. Becker et al. (2001) related different forms of energy such as input, specific, volume/mass specific energies to stress intensities and final product fineness. Other research studies focused on energy input in a stirred mill (Zheng, Harris and Somasundaran, 1996)."

Jan 1, 2011

By Donald Christofferson

This report documents the program conducted to demonstrate the application of a flywheel-powered propulsion system to underground mining shuttle cars. Such application can replace the present electrical trailing cable common to most shuttle cars and thereby eliminate those safety hazards, maintenance problems, and haulage route limitations inherent in the trailing cable. Described are the activities undertaken to specify and design a flywheel of optimum size, shape, and material; to identify the best concepts of input and output systems; and to achieve installation of the power package into a shuttle car. The resultant Flywheel-Powered Shuttle Car is an FMC Model 6L shuttle car, 6-ton capacity, 20-ton gross vehicle weight, powered by a flywheel system with 4.5-kilowatt-hour usable energy. The completed vehicle was delivered to the Bureau of Mines in Bruceton, Pennsylvania, for testing and evaluation.

Jan 1, 1986

By C. Heckman, M. S. Moats, A. Luyima, W. Cui

"Cyclic voltammetry, electrochemical impedance spectroscopy (EIS), and galvanodynamic and chronopotentiometric techniques were used to characterize the effects of DXG-F7®, a commercial smoothing agent, on copper electrodeposition onto 316L stainless steel from a synthetic electrolyte containing 40 g/L copper (Cu2+), 160 g/L sulfuric acid (H2SO4) and 20 mg/L chloride (Cl-) at 40oC. The findings were compared against results using HydroStar® 4208, a modified polysaccharide. The nucleation overpotential and plating potential observed in cyclic voltammetry and galvanodynamic testing showed that neither DXG-F7 nor HydroStar significantly polarized acidic copper electrodeposition. Subtle differences between the additives were found during EIS testing and modeling, but more research will be needed to fully understand these differences. Surface-roughness measurements of two-hour deposits indicate that DXG-F7 and HydroStar produced smoother deposits as their concentrations in the electrolyte increased. No difference in the surface roughness of deposits was detected between the additives. Based on the experimental evidence resulting from the laboratory testing, no significant difference was found between DXG-F7 and HydroStar at 20 mg/L Cl- concentration, with the exception that DXG-F7 dissolves more easily in water than HydroStar. Introduction Cathode deposits obtained from acidified copper sulfate electrolyte(s) without organic additives are often soft, coarsely crystalline and nodular (Sun and O’Keefe, 1992). Therefore, small amounts of organic additives are added to the electrolyte to produce level and dense cathodes during copper electrowinning. The action of organic additives is thought to be due to their adsorption on the surfaces of the newly formed copper grains. Hence, any copper grain that grows excessively fast adsorbs a layer of organic additive, which inhibits growth. The result is a smoother and harder deposit of suitable purity (Sun and O’Keefe, 1992). In part I of our four-part series on the examining of copper electrowinning smoothing agents, a review of previously published work on organic additives used during copper electrowinning was presented (Moats, Luyima and Cui, 2016). In the review, it was noted that many tankhouses had switched from guar to other saccharide-based products such as HydroStar and DXG-F7."

Jan 1, 2016

The annual general meeting of the Branch was held at the St. Helena Club on Thursday, August 21, 1969. Mr J. G. Kirchner (Chairman) was in the Chair. Also present were Mr R. C. J. Goode, President of the S.A. Institute of Mining and Metallurgy; Nine Members: Messrs N. A. Honnet, W. R. Lawrie, J. N. Saunders, D. D. Waterman (Committee Members), M. G. Cullen, G. C. P. Labuschagne, H. A. G. Slater, I. G. Thomas, T. Zadkin and Nine Associate Members: Messrs R. Campbell, D. E. Couperthwaite, T. M. Espach, J. M. Ferguson, G. W. Futcher, A. G. C. Merson, E. R. Penny, R. B. Sutherland, J. W. van den Munckhof and One Visitor: Mr D. J. McLaren. The Chairman declared the meeting open and, on behalf of the Branch, thanked the President for coming from Johannesburg to attend. MINUTES OF THE PREVIOUSGENERALMEETING As the Minutes of the General Meeting held on June 18, 1969 had not yet been published in the Journal, the Chairman moved that their adoption and the discussion thereof be deferred to the next General Meeting. This motion was adopted unanimously. CHAIRMAN'S ANNUAL REPORT 1968/69 At Mr Kirchner's request, Mr. R. C. J. Goode took the Chair during the presentation of the Chairman's Annual Report. (This report was published in the August 1969 issue of the Journal.) OFFICE BEARERS AND COMMITTEE MEMBERS FOR THE YEAR 1969/70 The Chairman announced that the outgoing Committee had elected the following office bearers for the coming year: Chairman: N. A. Honnet; Vice-Chairman: J. N. Saunders; Immediate Past Chairman: J. G. Kirchner. The Chairman then read a letter from the scrutineers reporting that the following had been elected to the Committee: M. S. Grobler, W. R. Lawrie, L. O. W. Leimer, A. T. Lewis, R. S. Pearson, T. Zadkin. The Chairman thanked the scrutineers for their services, and congratulated Messrs Lawrie, Leimer and Zadkin on their re-election and Messrs Grobler, Lewis and Pearson on their election to the Committee. The Chairman announced that he had heard, with regret, that Mr. T. Zadkin would be leaving the O.F.S. at the end of August, 1969. Mr Zadkin had served on the Committee continuously since the inception of the O.F.S. Branch and records showed that he had only failed to attend three General Meetings in over nine years. The Chairman expressed the gratitude of the Branch for Mr Zadkin's invaluable services to the Institute, congratulated him on his well earned promotion and wished him well in his new position. INDUCTION OF CHAIRMAN The Chairman introduced Mr N. A. Honnet to the meeting by briefly outlining his past career and, after congratulating him on his election, called upon him to take the Chair. In congratulating the out-going Chairman on a very successful term of office, Mr Honnet said that due to the absence of many Committee Members for a large portion of the year Mr Kirchner had carried a heavy burden, and he moved a vote of thanks and appreciation for Mr Kirchner's efforts. This was carried unanimously. GENERAL BUSINESS There were no points raised under this heading. MINING AND METALLURGICAL CONGRESS The Chairman called on Mr W. R. Lawrie to give his talk on aspects of the Mining and Metallurgical Congress recently held in Britain. This presentation was illustrated with photographic slides and proved of great interest to Members. Mr D. D. Waterman proposed a vote of thanks to Mr Lawrie and the Chairman then asked Mr R. C. J. Goode to contribute to Mr Lawrie's address. Mr Goode thanked Mr Kirchner for his efforts during his very successful term of office and congratulated the in-coming Chairman and Vice-Chairman on their election. He then gave a brief talk on aspects of the Congress not dealt with in Mr Lawrie's address. These included the industry's requirements of graduates, the necessity of their rapid advancement and the desirability of sending such young men to attend future Congresses. Mr Goode announced that two symposiums will be sponsored by the Institute next year, one on Tunnelling and the other on Open Cast Workings.

By Alexander May

The U.S. Bureau of Mines conducted studies to determine if phosphate slag stockpiles at Tennessee Valley Authority's National Fertilizer Development Center were hazardous materials. The stockpiles were not hazardous materials as determined by Environmental Protection Agency (EPA) extraction procedure (EP) toxicity test. Radium-226 concentration was 28.7 pCi/g in slag and 2.1 pCi/g in background material. Radium-226 was not leached from the slag. Fluoride concentration was 3.87 pct in slag, 0.18 pct in subsurface material under slag, and 0.08 pct in the background. Slag material permeability was 1.65 x 10-3 cm/s, and subsurface material permeability was 3.24 x 10-6 cm/s. Rain water, trapped in a depression on top of the east slag stockpile, became seepage water at the base of the stockpile. Concentrations of EPA toxic elements in seepage water were much less than concentrations from an EPA EP toxicity test on the slag. Twelve elements-Na, Mg, Ca, Sr, Ba, Cr, Mn, Co, Cu, Cd, AI, and P-had higher concentrations in seepage water than in rain water on top of the slag stockpiles, or in creek water adjacent to stockpile bases, indicating that they were leached from slag stockpiles.

Jan 1, 1990

By D. D. Macdonald, G. Engelhardt

The accumulation of damage due to localized corrosion [pitting, stress corrosion cracking (SCC), corrosion fatigue (CF), crevice corrosion (CC), and erosion-corrosion (EC)] in complex industrial systems, such as power plants, refineries, desalination systems, etc., poses a threat to continued safe and economic operation, primarily because of the sudden, catastrophic nature of the resulting failures. Of particular interest in managing these forms of damage is the development of robust algorithms that can be used to predict the integrated damage as a function of time and as a function of the operating conditions of the system. Because complex systems of the same design rapidly become unique, due to differences in operating histories, and because failures are rare events, there is generally insufficient data on any given system to derive reliable empirical models that capture the impact of all (or even some) of the important independent variables. Accordingly, empirical models have generally failed to provide a robust basis for predicting the accumulation of corrosion damage in complex systems under realistic operating conditions. The alternative prediction philosophy is determinism, in which the development of damage is described in terms of valid, physico-electrochemical mechanisms with the output being constrained by the natural laws. The differential damage is then integrated along the corrosion evolutionary path for the system (i.e., over the future operating "history") to yield the desired integrated damage, which is the quantity that is most useful to an operator. In this paper, we review the theory of predicting corrosion damage within the framework of Damage Function Analysis (DFA), with particular emphasis on the pitting of aluminum in chloride solutions and on the accumulation of damage from SCC in Type 304 SS components in the primary coolant circuits of Boiling Water (Nuclear) Reactors (BWRs). These cases have been selected to illustrate the various phases through which localized corrosion damage occurs.

Jan 1, 2005

By Fred A. Webber

STEEL ROPE WIRE is one of the more specialized commodities among the many grades of highcarbon steel wires. In its production there are many metallurgical aspects of interest from the steelmaking on through the final stages of wire drawing. We produce rope wire in an integrated mill com prising all the operations from the blast furnaces to finished wire drawing in the wire mills. Steelmaking is carried out with close control on hot metal, selection of scrap, and fluxing materials. The basic open hearths are of 170 tons capacity. Steel is teemed into 19 1/2 in by 19 1/2 in big-end-down molds and is hot-topped with the use of clay refractory hot-tops. The weight of this ingot is 6,900 pounds. All high -carbon steel ingots are charged hot into the soaking pits and are then rolled through the blooming mill in 16 p asses to a bloom ax~ in. by 41/2 in. and approximately 65 feet long. Necessary bottom and top crops are taken on the bloom as it passes from the blooming? mill to the billet mill. The still hot bloom is continuously rolled through the billet mill in . 5 passes to a 2 3/8 in. square. Billets are cut to 32 feet in length by a flying shear and then allowed to cool on the hot bed.

Jan 1, 1957

By Hernando Labarthe

"El presente texto describe el desarrollo de la planta concentradora ubicada en Castrovirreyna, ubicada en Huancavelica como parte de las plantas de beneficio del Banco Minero del Perú. La Planta de Virreyna tieneuna capacidad de 50 toneladas diarias y por flotación selectiva se obtiene concentrados de zinc, plomo y cobre. El mineral a beneficiarse de diversas minas es transportado por camiones y almacenado en tolvas de madera y canchas de recepción con amplia capacidad. "

Mar 1, 1957

By Michael J. Klishis

Accident rates continue to show that underground mining jobs areamong the most hazardous occupations in the United States and roof bolter operators continue to have one of the highest accident incident rates (MSHA, 1991) despite efforts by labor, government, and industry to reduce and eliminate work-related hazards. In the last two decades we have seen technical innovations such as the ATRS, and there has been an increased emphasis on hazard awareness through programs such as MSHA's REAP, but bolter operators continue to be injured and killed. Researchers at West Virginia University examined risk in the roof bolter's job and developed new approaches to accident and injury prevention. The study concentrated on the workers' job performance, machinery and the work environment to identify miner's risk and hazard exposure while bolting.

Jan 1, 1993

By Brian Danyliw

"Dust control is an increasingly important consideration for all mining operations from a health, safety, environmental and maintenance perspective. Modern mining operations incorporate a variety of mechanical dust control techniques into design however in many cases these engineered systems are unable to meet desired fugitive dust level targets. In these cases a variety of chemical dust suppression options are available to operators to assist in meeting their targets. This paper provides an overview of available chemistries, discussion of application techniques and equipment requirements and available performance monitoring technologies. This paper will also include a number of case histories discussing the treatment approach chosen, challenges encountered, chemical feed, storage and application equipment, monitoring techniques employed and results achieved.INTRODUCTIONDust FundamentalsFugitive dust by definition is an aerosol consisting of particulate matter suspended in a gaseous medium. Aerosols can include suspensions of particulate (solids) or sprays (liquids) or a mixture of both. Of particular concern from an occupational health and safety perspective are aerosols of particulate matter due to their involvement in classical occupations lung diseases such as silicosis, poisoning through chronic exposure to compounds such as lead and beryllium and expected involvement in more modern identified conditions such as cancer, asthma, and a host of other respiratory and non-respiratory conditions which may be caused or influenced through exposure to dust.According to the ""Glossary of Atmospheric Chemistry Terms"" (IUPAC, 1990), ""Dust: Small, dry, solid particles projected into the air by natural forces, such as wind, volcanic eruption, and by mechanical or man-made processes such as crushing, grinding, milling, drilling, demolition, shoveling, conveying, screening, bagging, and sweeping. Dust particles are usually in the size range from about 1 to 100 µm in diameter, and they settle slowly under the influence of gravity."" It should be noted that the behavior of particulates with respect to settling rate in air is a function of particle mass and shape and therefore the geometric size of the particle can be misleading. Occupational hygienists utilize the concept of particle aerodynamic diameter as a more representative reflection of particle size. Particle aerodynamic diameter, is defined as ""the diameter of a hypothetical sphere of density 1 g/cm3 having the same terminal settling velocity in calm air as the particle in question, regardless of its geometric size, shape and true density."" The expression of particle size as aerodynamic diameter allows for a more consistent understanding of particle behavior both from a settling perspective as well as from the perspective of how dust particles will behave in the respiratory tract. Figure 1 illustrates settling rates for particles of various aerodynamic diameters. The relationship between particle size and settling rate is important for understanding what size of particles must be addressed by dust control strategies as well as what particle sizes represent the most danger from an exposure and occupational health perspective."

Jan 1, 2015

By Robert C. Horton

The Getchell Mine is located on the east flank of the Osgood Mountain Range in the Potosi Mining District, Humboldt County, NV. Mining in the area first began in 1883 for copper, lead and silver in skarn-related deposits. Tungsten was discovered in the skarns in 1916 and was mined sporadically until 1957. The first major discovery was made in 1933 when two Winnemucca prospectors, Edward Knight and Emmett Chase, found gold at the present site of the Getchell gold mine. In 1934, after a small amount of preliminary prospecting, the claims were purchased by Noble H. Getchell of Midas, NV. The Getchell Mine Inc. was organized and exploration and development work began on a broad scale. Major funding was provided by George Wingfield and investors he assembled. Laxalt described Wingfield’s immediate history prior to his financing of Getchell as follows.

Jan 1, 1999

By Clayr Alexander

Stillwater Mining Co. (SMC) is engaged in developing, extracting, processing and refining palladium, platinum and associated metals (PGM)from the J-M Reef. This geological formation is located in Stillwater, Sweet Grass and Park counties in southern Montana. Associated byproduct metals include rhodium, gold, silver, nickel and copper. SMC’s current mining operations are near Nye, MT. The company is currently developing a second underground palladium and platinum mine, the East Boulder project, about 21 km (13 miles) west of the Nye operations. A 5,650-m (18,550-ft) tunnel is required to gain access to the ore-bearing horizon (J-M Reef).

Jan 1, 1999

By J. Dvorácek

Similar to the case of any other business venture, the activities of mining industries are profit-oriented. Nothing will stop successful businesses in their quest for new localities to be prospected for minerals of their choice, because the useful economic life of any mine is limited. Before starting the process of land acquisition, it is important for any mining company to be able to forecast the profitability of the venture. The focus of this paper has been on the prospects of success, concerning the case of the opencast extraction of aggregates for construction. A set of 70 successful and loss-making quarries was subjected to investigation. An international company owns the quarries, which are located in seven European countries. The method of discriminate analysis provided the criteria for assessing future economic performance. The same criteria served the purpose of classifying other quarries belonging to the company.

Jan 1, 2012