Search Documents

By Krystyna Raszka, Jerzy Iskra

The paper presents results of spectrophotometric investigations concerning the adsorption of sodium oleate on silicon carbide in the presence of the cations of multivalent metals, applying the ATR IR technique with computer-aidedprocessing of the spectrum. The analysis of these spectra indicates the occurance of distinct OH and COOH bands in the pH range in which the hydroxy complexes of metals of the type MeOH+ and MeOH++ reach in the respective cases the highest concentration in the solution. The correlation of these results with those of flotation, measurements of the zeta potential confirms the proposed mechanism of activation of the flotation of silicon carbide, applying sodium oleate as a collector, the collection taking place over the adsorption of hydroxy complexes of the type MeOH+ and MeOH++

Jan 1, 1995

By Tim O’Neil

Big and getting bigger. Barrick Gold Corp., the third-largest gold producer in the world, began production in September — ahead of schedule — at its Meikle Mine. At a scheduled full production rate of 12.4 t/a (400,000oz/year), it will be the largest producing underground gold mine in the United States. The $180-million Meikle Mine is located on Barrick’s Goldstrike property in Nevada and has 205 t(6.6 million oz) of gold reserves. The compact Meikle deposit has an average ore grade of 23 g/t (0.68 oz/st), making it one of the highest-grade mines in the country.

Jan 1, 1996

By Jozef Szymanski, Julian Partyka, Jerzy Krynicki

In order to study blast-induced dust in a hard rock metal mine experimentally and analytically, a part of a stope mined by Vertical Retreat Mining (VRM) was monitored throughout its lifetime. Dust measurements were used to describe the dust source, to study the dynamics of removal of airborne dust from the blasting area, and to examine a variation in dust production with a stope's progress. An analysis based on graphical and analytical comparisons of blasts taking place in a single stope is presented and discussed. Also, some transient phenomena of dust flow in the stope vicinity, caused by the blasts only, are examined.

Jan 1, 1997

By J. Searls

The potash review arrived too late to appear in the June issue. Potash is a general term that includes several water soluble potassium salts: potassium chloride (muriate of potash), potassium sulfate (sulfate of potash), potassium magnesium sulfate (sulfate of potash-magnesia), potassium nitrate (niter) and sometimes potassium carbonate. Potassium carbonate was the original potash when it was leached from wood ashes and dried in large, cast iron pots to black-to-gray crystals (ash) to form "pot ash." "Pearlash" was potash roasted to white crystals. In modern terminology, the great preponderance of "potash" is the mined forms. It is estimated that 95% of the potash mined around the world is used as fertilizer. In 1840, Justus von Liebig demonstrated to the scientific community the importance of potassium to the growth of plants. But there was no low-priced source of potash available at that time. In the winter of 1851-1852, minable potash was discovered near Stassfurt,

Jan 1, 1991

By Gregg J. Hodges

The Stillwater Mining Co. is a partnership of The Pittsburg & Midway Coal Mining Co. and Manville Corp. The Stillwater Mine, located near Nye, MT, is the Western Hemisphere’s only primary platinum-palladium deposit. The mine began production of flotation concentrates in March 1987. In the fall of 1987, an integrated pilot plant testing campaign of electric furnace smelting and oxygen-blown converting confirmed the feasibility of further upgrading to semi-refined matte, or “white metal.” In the summer of 1990, the production smelter was brought on line. The record of the discovery and development of the Stillwater deposit, mine and concentrator has been summarized in several articles (White, 1987; Kennedy, 1987; and Hodges and Clifford, 1988). Similarly, the pilot campaign to test the feasibility of treating the flotation concentrates in an integrated smelting plant has been described (Hodges and Clifford, 1988; Matousek, et al., 1989; and Matousek and Whellock, 1990).

Jan 1, 1991

By Y. C. Kim

One-quarter of a century has passed since the "theory of regionalized variables" (geostatistics) was introduced by G. Matheron (1962, 1963) in France. Yet, only during the past decade has geostatistics found broad acceptance in the mining industry. Foremost among the reasons for this time lag was ignorance. The first English treatise on geostatistics was not written until Matheron (1971), and the first published text accessible to mining professionals did not appear until David (1977). Other significant reasons for the slow acceptance of geostatistics included the conservative nature of management in the 1970s minerals industry, and the fact that conventional ore reserve estimation performs reasonably well when confined to massive deposits of base metal and iron deposits having relatively low coefficients of variation in grades. In short, mine engineers and geologists were not willing to accept a new set of tools for problems that they did not see.

Jan 1, 1989

By M. J. Zdunczyk

Sand is one of the most common materials on the earth’s surface. It is a naturally occurring material resulting from the physical and chemical breakdown of rocks. The definition of sand varies, as do the number of products made from the material. Sand is generally classified by grain size, however the measurement or scales differ depending on the context in which it is being used. Geologist define sand as particles of rock between .05 and 2 millimeters in diameter. The variability of the mineral composition generally dictates which sand can be used for different industrial purposes. For example, sand used for Portland cement concrete and asphaltic concrete mixtures can be very different in physical and chemical composition than sand used in the making of fiberglass. In this paper, construction uses of silica sand, which consists almost entirely of the mineral quartz (SiO2), will be discussed and analyzed.

Jan 1, 2001

By M. Tirmarche, J. Brenot, J. W. Piechowski

INTRODUCTION Statistical analysis of results obtained by workers survey is very often limited to the determination of the collective dose and mean annual values. This information is not sufficent by itself for radiation protection purposes since the cumulative exposure of a worker during his working life is not taken into account. A more complete analysis would be obtained by considering both: [ ] These two notions are different. The former depends on the evolution of the protection with time and is related to annual limits (ICRP, 1977 and ICRP,1977 a). The second depends mainly on the works performed during the period of survey, the interference of protection evolution is weakened. So it is useful to foresee how the individual average annual doses would be when considering survey periods of 5, 10 years, or more. STUDIED POPULATION In order to analyse the two previously mentionned notions it is necessary to follow up a well defined population of workers which is continuously exposed to the radiological hazards on a long enough period. The selected population is that of the workers of the French uranium mines always present during the 1971-1979 period (9 years). The number of individuals is 937. The radiological hazards are: 1. exposure to radon and short-lived daughters 2. exposure to long-lived ore dust 3. external irradiation. The workers of the uranium mines are exposed to these radiological risks in different ways according to the work performed. It is therefore necessary to subdivide the population into more homogeneous groups with respect to the radiological risks. Three groups are considered: - Group 1 : 227 individuals whose radon and dust exposures are always nil - Group 2 : 449 individuals whose radon and (or) dust exposures are different from 0 every year - Group 3 : 261 individuals represent a mixed category. Some features of these groups are given in table 1. [ ] The 937 followed individuals represent approximatively the half of the whole population of the French uranium mines. Taking into account the procedure adopted to select the studied population, it appears clearly that this population is not representative of the whole miner population. DOSIMETRIC RECORDS Three risk indicators are considered .Individual annual exposures to radon and its shortlived daughters. They are determined by ambient monitoring based on radon concentration measurements and recording of the times elapsed in the various workplaces. For each worker the annual exposure is represented by the mean annual air concentration and is expressed as a fraction of the maximum annual concentration (MAC). Given the administrative arrangements and the effective state of equilibrium between radon and its daughters, the maximum annual concentration is practically equivalent to 1 Working Level = 2.08 x 10- 5 jm-3. (UNSCEAR, 1977). . Individual annual exposures to long-lived ore dust which are also expressed in fraction of the maximum annual concentration. . Individual annual doses of external irradiation (X and [y] rays) expressed in mSv (= 10-3 Sievert). Irradiation monitoring is based on use of individual film badges.

Jan 1, 1981

Growing concerns of climate change and its potential association with the release of greenhouse gasses to the atmosphere have prompted possible legislation which would require minimization of greenhouse gas emissions. Carbon dioxide and methane, both of which largely contribute to the greenhouse effect, have direct links to the fossil energy industry sector. Specifically, the combustion of one ton of coal produces between one and three tons of carbon dioxide, dependent upon the carbon content and heating value of the combusted coal. Additionally, coal mine methane (CMM) released through a mine?s ventilation system has a radiative trapping impact approximately 20 times greater than that of an equivalent mass of carbon dioxide. The capture of coalbed methane (CBM) prior to the mining process and its utilization as an alternative energy source provides the possibility of a decreased carbon footprint. Domestically, the past 25 years have seen a significant expansion of the CBM industry. Internationally, in developing countries such as China, the need for western coal degasification technology is growing. A collaborative, international effort will be required to initiate a recognizable decrease in global greenhouse gas emissions. This paper identifies the potential decrease in equivalent carbon dioxide emissions through effective degasification at a hypothetical longwall mine located in China. Advanced, three-dimensional gas reservoir simulation software will be utilized to determine the maximum feasible CBM recovery in a low permeability, high gas content reservoir prior to the mining process.

Jan 1, 2010

By Tench C. Page

The Yarnell gold deposit is located 1.5 km (1 mile) south of Yarnell in the Weaver mining district of Yavapai County, AZ (Fig. 1). Elevations within the area of the deposit range from 1400 to 1560 m (4590 to 5120 ft). Historic production, principally from quartz veins localized along the Yarnell fault, was about 200 kt (220,000 st) at an average grade of 6.9 to 10.3 g/t (0.2 to 0.3 oz/st) gold. The federal government closed the mine in 1942 due to World War II. Norgold Resources Inc. leased the property in 1988 and joint ventured it with Asarco the same year. Asarco drilled 7822 m (25,660 ft) in 96 reverse circulation and four diamond drill holes and identified 8 t (260,000 oz) gold reserve. IBema Gold Inc. acquired Norgold in 1991 and is currently permitting the project. Production is expected to begin within the next two years

Jan 1, 1994

By M. Josick Comarmond, Paul L. Brown, Greg P. Timms, A. Ian M. Ritchie, John W. Bennett

Geochemical kinetic models have only become available in recent years and their utilisation in the prediction of effluent chemistry from sulfidic waste rock piles is even more recent. The models used to date, however, have incorporated some questionable assumptions. This paper shows how geochemical, mineralogical and physical field data have been coupled to remove some ill-founded assumptions in the construction of a geochemical kinetic model. Further, the paper discusses a comparison between the observed effluent chemistry from a waste rock dump at the Rum Jungle copper/uranium mine in northern Australia with model predictions. In general, there is good agreement between the two, although an anomalous result is discussed.

Jan 1, 2000

With the rapidly growing use of hydraulics in mining equipment, maintenance personnel should be familiar with the various components in hydraulic systems. Hydraulic systems do wear out - the fluids they transport are hot and turbulent, the equipment they power often imposes tremendous pressure pulsations and bending stresses, and the working environment is harsh. Therefore, even though hydraulic hoses are made of remarkably trouble-free components, they do need to be replaced periodically. There must be coupling methods that allow hoses to be replaced without disturbing other components. Couplings must also provide a variety of leak-resistant connections between hoses and other components in the hydraulic circuitry. Threaded Connection and Seals Hydraulic coupling thread ends and sealing arrangements are standardized, with many types available. Their outward appearance varies, but coupling configurations are recognizable by examining threads and seals and comparing them to the examples provided here. Iron Pipe Thread There are two kinds of iron pipe threads normally used in mining equipment circuitry - National Pipe Tapered Thread for Fuels (NPTF) and National Pipe Straight Thread Mechanical Joint (NPSM). The NPTF seal is the engagement of the coupling threads, called thread interference. When tightened, the tapered thread of the male fitting binds into that tapered thread of the female fitting to form a relatively leakproof seal (Fig. 1). In the NPSM seal, there is a 30° angle seat machined into the end of the male NPTF fitting. This seat engages with a mating 30° angle cone on the inside of the female fitting. Female NPSM fittings have straight threads, as opposed to the tapered threads of the NPTF fittings. However, most NPTF solid male fittings also have a 30° angle seat enabling them to be used with NPSM female fittings (Fig. 2). JIC and SAE Fittings Joint Industry Conference (JIC) and Society of Automotive Engineers (SAE) seals are formed by joining two mating, conical metal surfaces. The coupling threads are used to bring and hold these surfaces together to form a leak-resistant seal. A JIC connection is a solid male threaded end, with a 37° machined male nose, mating with a 37° female flare seat. When connected, the mating surfaces are held together by the threads, but the threads do not form the seal. The female seat is created by flaring a tube end or machining the interior surface of a stem to 37°. A female JIC has a swivel nut, allowing the sealing surfaces to be joined together without twisting a hose or twisting the seats against each other (Fig. 3). JIC couplings are frequently used on low, medium, or high pressure hydraulic circuits on mining equipment and machinery. The SAE connection is similar in appearance and sealing characteristics to the JIC system, except the angle of the machined male nose and female flare seat is 45° (Fig. 4). "O" Ring Fittings Seals for "O" ring fittings are formed by compressing an "O" ring against an exposed machined surface on a mounting block or hydraulic component part. The "O" ring must be compatible with the type of hydraulic fluid used (Fig. 5). An "O" ring boss connection is made of a male straight thread

Jan 10, 1983

By Prasannarao Dontula, Kal V. S. Sastry

Advances are made in the field of mineral processing on a continuing basis both in the industry and the academia. These advances do not always get used fully because of the inherent difficulties in the transfer of knowledge and reduction to practice. In recent years, knowledge engineering is being increasingly employed in other fields to overcome some of these difficulties. This paper presents a vision of how knowledge engineering can be applied to the benefit of the mineral processing industry and includes a discussion of associated principles, techniques, and advantages.

Jan 1, 1993

By Daniel J. Kennedy, George W. Klinowski

A significant portion of each mine is ventilated with the help of auxiliary fans delivering fresh air to the faces of its developing headings via flexible or rigid ducts. Quality and volumes of air delivered to the blind working faces are essential for creation of safe and acceptable conditions for employed crews. Well designed and properly maintained delivery systems are necessary in each mine. The Cape Breton Coal Research Laboratory, part of the Canada Centre for Mineral and Energy Technology located in Sydney, Nova Scotia, Canada, developed a tracer gas based technique which provides fast and accurate evaluation of any auxiliary ventilation system performance. In addition, important information about the system's behaviour is gathered which can be used for designing a similar system in comparable conditions.

Jan 1, 1989

By David M. Miller, Pramod C. Thakur, Larry D. Taylor

The most common technique used to suppress respirable coal dust in air is that of spraying with fine water particles. The water droplets are typically much larger than respirable dust particles and they collect dust particles mainly by interception. Dust collection efficiencies can be improved by reducing the droplet size and in- creasing the droplet velocity. This is typically done by reducing the surface tension of water and increasing the water pressure. Dust collection efficiency can be further improved by in- creasing the electrical attraction between the water and dust particles through electrostatic charging. A technique developed by Conoco accomplishes both surface tension reduction and electrostatic charging by discharging weak solutions of surfactants in water at high pressures, 13.8 to 27.6 MPa (2000 to 4000 psi) in an intrinsically safe manner. The paper de- scribes the process and presents related dust suppression data.

Jan 1, 1986

By E. Topuz, M. J. McPherson, I. M. Konduri

Theoretical investigations and laboratory experiments demonstrated that there is a great potential for the use of jet fan ventilation in mines. This paper summarizes research that consisted of laboratory-scale model tests, full-scale mine model tests and underground coal mine entry tests. The laboratory model used water as a fluid medium and simulated a typical 25-m- (82-ft-) long heading having a 1.5 x 6-m (4.9 x 19.7 ft) cross section. The effects of various nozzle positions and designs were investigated by using still photography. It was also found that the use of jets in combination with line curtains enhanced the overall ventilating effect in the model entry. Flow measurements in the full-scale mine model and in the coal mine entry were conducted to evaluate the effectiveness of the jet fan. It was concluded that the designed jet fan ventilation system was an effective means of ventilating blind airways.

Jan 1, 1998

By Michael T. Ballard

The key to productive computer usage is system software integration with full compatibility among individual components. The majority of software developers in our industry are still in the process of perfecting individual components. As a result, exchange and validation of data between disciplines becomes an arduous process. We at Morrison Knudsen Engineers, Inc. (MKE) have integrated an entire system, allowing exploration, geology, modeling, mine planning, and operation modules to work as a single, complete system with direct exchange and validation of data. The importance of integration to both developers and users of today's mining soft- ware is becoming increasingly apparent as we, an industry, move toward growth and enhancement of the technology of ore reserve acquisition, evaluation, and management. It is also important to understand the present state of integration and where it is leading US. Not long ago, another industry passed through the same stages we are now setting up for the mining industry. The stereo industry began with a few individual components, the record player, tape recorder, and radio. People were able to play records, listen to the radio and record conversations and music only through microphones on their tape recorders. Soon, one enterprising individual discovered he could tape sound directly from the radio or record player by capturing audio output from the speaker wires. Interfaces and patch cords were developed, providing a means to transfer audio information between components with not only little loss of sound quality, but also the elimination of back- ground noise. The industry took another step forward with the introduction of "integrated" stereo, where the components were packaged in one cabinet with shared resources. This reduced overall cost which paved the way for better quality. Today's stereos are now so well integrated that many of the components share data and resources from the same manufacturer, designed to work together for almost perfect data transfer between any of the components. The result is better sound, convenience, and reduced cost. This is the ultimate goal for integration. Any system development passes through these same steps on the road to total interaction. Initially, the components are designed, tested, and marketed individually, often by separate companies. As the users become familiar with the components, the need arises for an automatic interface between the components. This is necessary to cut down on error during data transfer and to eliminate the redundant work required to enter results from one component into the next component in the system. As a result, interfaces must then be developed to aid in this data transfer. After data transfer is accomplished, the next step is resource sharing. Resource sharing is careful design and engineering by either cooperative, individual manufacturers or one firm taking on the task to produce a single package product. Design and resource sharing leads to lower overall cost, while still providing component capability with options to grow as the user grows. The mining software industry has been working to develop some very high quality component software and has indeed accomplished this task in every aspect of the mining industry. However, realizing the importance of integration, some companies with limited individual resources have started working together to interface their individual components. Other firms have undertaken the project of developing complete, integrated systems.

Jan 1, 1987

By Leo Langland

One of the primary functions of the Geotechnical Services-Materials section of the Arizona Department of Transportation (ADOT) is locating, sampling, and evaluating potential aggregate deposits throughout the State. This information is essential in designing, estimating, and bidding highway construction projects. The nature of materials used for aggregate varies greatly within Arizona. The northeastern or plateau section is famous for its scenic sedimentary formations that are, how- ever, too soft to make suitable aggregate. Volcanic materials are widely used in place of more conventional geologic units. In contrast, the southwestern, or Basin-and-Range section, contains a relative abundance of good aggregate, especially a diversity of gravels. The paper will review the off ice, field, and laboratory methods used by the ADOT Materials Section in satisfying its needs for aggregate information in Arizona.

Jan 1, 1987

By J. R. Diehl, R. W. Lai, R. W. Hammack, S. U. M. Khan

Cyclic voltammetry (CV), flotation response, evolved-gas analysis (EGA), and X-ray photoelectron spectroscopy (XPS) were employed to evaluate the major differences in the surface property and surface reactivity of a selected coal pyrite and a mineral pyrite. Surface properties of pyrite were evaluated in terms of flotation response in the presence of both an anionic fluorosurfactant and sodium hydrosulfide. The charge transfer adsorption and oxidation potential of sodium hydrosulfide were evaluated using cyclic voltammetry. Drastic differences in the flotation response have been observed between the coal pyrite and the mineral pyrite. Significant differences in the cyclic voltammograms at pyrite surfaces of these two sources were also observed. Measurements by XPS and EGA were used to determine the oxidation products and the rate of oxidation of the coal-pyrite and the mineral-pyrite surfaces.

Jan 1, 1991

By R. Kramer

The Process Mineralogy review arrived too late to appear in the May issue. The Process Mineralogy Committee scheduled programs with both SME and The Metallurgical Society. At the 1991 SME Annual Meeting in Denver, CO the committee sponsored five sessions containing 31 papers. Four process mineralogy sessions were sponsored at the 1992 annual TMS meeting in San Diego, CA. Process mineralogy is used to understand and evaluate mineral behaviors during mineral beneficiation, phase reactions during metallurgy, recoveries and reactions of precious metals during processing and mineral and phase behaviors with respect to environmental problems. The most recent refinement in mineralogical studies with respect to mineral beneficiation has been the wider use of image analysis and combined materials balancing techniques of image analysis data. Image analyzers that can perform analysis with respect to mineral beneficiation are expensive. They are used only for solving major processing problems. Nevertheless, the methodology of analysis continues to be refined. Much better data are collected, and methods of evaluating the data continue to improve. One interesting development involves modifying the ultrasound unit used in medical studies to perform a three-dimensional analysis of ore particles.

Jan 1, 1992