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By Vathsala Rajagopal, lwao lwasaki

The grinding media materials for the mining industry require corrosion and abrasion resistance properties not only to minimize the wear but also to improve the flotation recoveries of sulfide minerals. The media wear mechanisms and the factors influencing the grinding ball wear during grinding are discussed with respect to abrasion, corrosion and impact wear of grinding media materials. Interactions between the grinding media and sulfide minerals in a ball mill adversely affect the floatabilities of the ground minerals. The possible galvanic interactions between grinding medium-mineral and their effects on the flotation responses of sulfides are also reviewed. The selection criteria for alloy composition that reduces the overall wear along with adverse effects on flotation are brought out.

Jan 1, 1992

By John D. Kalasky

Island Creek Coal Company has had, for many years as a primary concern, the activity of handling large quantities of methane in the ventilation of its deep mines of southwest Virginia. Since the development of the Beatrice operation in the mid 19601s, the concern has been well founded, and through the years progress has been made in this most important facet of the extraction of the coal reserves to insure the safety of the employees engaged in the mining opera- t ions.

Jan 1, 1980

By A. M. Al Taweel, V. K. Kasireddy

Intensive coal cleaning usually necessitates fine grinding of the feed in order to liberate inorganic constituents from the surrounding organic matrix. This however adversely affects the ability of flotation techniques to beneficiate coal. Such difficulties are mainly attributed to the increase of particle population density, the decrease in capture efficiency, and the greater tendency of inorganic components to report with the froth. A three-pronged approach was adopted in an attempt to overcome these difficulties. The aggregative flotation technique was used to reduce particle population densities and improve capture, while unconventional spargers were used to generate a wide range of bubble sizes. Use of unagitated flotation columns allowed for the maintenance of countercurrent flows in both the recovery and washing sections. The combined effect of these parameters enabled the recovery of 92% of the carbon content of coal having an average particle size of 20.5 µ m, while rejecting 85% of the ash. This was accomplished using 2 kg of fuel oil per tonne of coal in a column 2 meters high operating at 2-3 tph/m3, a capacity which compares favourably with conventional cells.

Jan 1, 1989

By Shigeru Sarata

Working places in underground mines are formed by digging. The main feature of underground working places is that they are surrounded by rock. Digging through rock, which is main operation of mining, generates great reacting force. In many cases, supports are required to maintain a roof. Working places change their location with progress of mining operation. Therefore, for automate the work in such environment, a locomotive mechanism which can endure great reacting force, can support effectively the roof and floor, and has high moving performance in rough environment, might be required. In narrow underground environment which is surrounded by rock, it is possible to generate great fixing force by means of a jack which is set between the roof and floor or both side wall it is usual to apply a jack as anchor post for fixing machinery or reacting force. Self advancing supports widely used in long wall faces in coal mines could be said an example of locomotive mechanism with propping up fixing method. However it is difficult to say that ordinary self advancing supports have enough adaptability for various condition of the roof and floor. New locomotive method for underground working place 'Swing Phase Locomotion' is proposed. It is achieved by mechanism based on frame type support and synchronous control of jacks. Furthermore, to achieved high adaptability to various conditions of the roof and floor, another walking mechanism has been developed. The mechanism employs propping up jack as its legs.

Jan 1, 1989

By D. S. Cavers

INTRODUCTION This paper discusses aspects of rock engineering applicable to surface gold mines. Discussion particularly centers on areas in which rock mechanics can enhance the mine productivity or profit- ability. Methods of analysis are discussed briefly but for more detai1s the reader is referred to the appropriate references. A team approach to the overall design of the pit generally pro- duces a better result at an overall lower cost. In particular, money is wasted by asking for a "report on slopes" and then input- ting this slope angle into a pit design and economic analysis study without further reference to the geotechnical engineer. Pit slope angle depends on slope orientation, location, pit shape, pre-existing discontinuities and mining methods. Preliminary slope angles can be produced but optimization depends on ongoing inter- action between the mining engineers, geologists and geotechnical engineers. This interaction can a1 so substantially reduce overall design time which may be critical in bringing remote plays into production. Most surface gold mines in North America are in igneous or metamorphic environments. Rock mechanics aspects discussed in this paper will be discussed with reference to these environments al- though most of the principles and comments are applicable to sedimentary environments as we1 1.

Jan 1, 1987

By R. Henley, S. S. Webster, L. Harris

High resolution airborne magnetic and radiometric data have been shown to optimize exploration for epithermal gold deposits in the vicinity of Charters Towers, northeastern Queensland. The radiometric data allow extrapolation of poorly outcropping geology to provide a cost-effective mapping technique, even at exploration scales (eg. 1:25,000). At a regional scale (eg. 1 : 100,000) the magnetic data reflect the regional tectonics and divide the area into domains for the application of different genetic models. For example: 1. the Ravenswood Batholith is characterized by multiple intrusions dating from Ordovician to Permian age. The polarity of the magnetic anomalies implies an age for the intrusions and indicates a deposit style for exploration. 2. extensional and wrench tectonics along the northern margin of the Drummond Basin are interpreted from the magnetic data and indicate favourable blocks for detailed exploration. Genetic exploration models may be tested in favourable environments by the recognition of geophysical signatures. These signatures reflect structural, lithological and alteration patterns arising from controls on ore deposits and can be applied at regional or detailed scales.

Jan 1, 1989

By M. Beus, S. Stewart, S. Iverson

Recent ore pass failures have underlined the need for improved designs, standards, structural monitoring methods and better hang-up prevention and removal techniques. Researchers at the Spokane Research Laboratory of the National Institute for Occupational Safety and Health (NIOSH) are investigating methods to improve safety during the transport of ore in ore passes. Design criteria and hang-up prevention and remediation strategies involve studies of the effects of static and dynamic ore and waste-rock loads on chutes, walls, gates and support structures. Particle flow analysis methods were used to simulate the response of various ore pass designs to a wide range of ore loading conditions. A full-scale mockup of actual ore pass and chute assemblies was duplicated and tested for load response. Data from a particle flow code and the mock-ups were compared Loads on an active ore pass chute were measured

Jan 1, 2000

By M. F. Gleason, S. Burns, J. R. Arnold

In 1986, Gold Fields began negotiations with a large Nevada electrical power utility to supply power for its Chimney Creek mine in northern Nevada. After the long negotiations reached an impasse over various costs associated with the power line, a decision was made by Gold Fields to generate its own power. Self-generation is not uncommon overseas, but it is rare for any but very large or very small operations in the United States. Surprisingly, under certain conditions a mine can generate its own power profitably, and Gold Fields has found that the associated operating and maintenance problems are minimal. The following report details what factors went into this decision and how it works. Hopefully, it can serve as a guideline for those who may find themselves in a similar position. History In the spring of 1986, Davy McKee Corp. was contracted by Gold Fields Mining Corp. to provide design engineering and construction management for the chimney Creek Mine. Chimney Creek is located about 50 mi northeast of Winnemucca, NV in a remote part of Humboldt County. The nearest industry using utility power was the Pinson Mine, about 13 mi from the proposed plant site. The existing electric line was not capable of carrying another mine the size of Chimney Creek, which required 29 million kwh per year. There were three options available to Gold Fields for the power supply: 1 )Power could be supplied by the public utility from a coal-fired plant about 30 mi away by constructing a new line to the mine,

Jan 1, 1991

By K. B. C. Brady, B. E. Scheetz, J. E. Cuddeback, T. W. Bergstresser, W. A. Telliard, S. C. Parsons, R. J. Hornberger

Two weathering procedures are being developed by the Acid Drainage Technology Initiative in cooperation with federal agencies(OSM and EPA). Objects are to: (1) standardize existing humidity cell and leaching column procedures; (2) improve test methods by maintaining a carbon dioxide enriched environment needed to optimize carbonate mineral dissolution, and quantifying particle size variables to evaluate reaction kinetics, and (3) provide flexibility in test method implementation consistent with EPA guidelines for Performance-Based Measurement Systems. Preliminary results indicate the CO2enriched leaching environments produce alkalinities that are similar to field observations and greater than the tests run under atmospheric PCO2. Leaching columns produce higher alkalinity than humidity cells.

Jan 1, 2003

By Edmond Donovan, O&apos

With the increase in complexity of conveyor systems and the inexorable demand for more capacity and availability, the ability of designers to accurately predict performance is becoming increasingly important. Dynamic analysis techniques for modelling wave mechanics in conveyors are finding increased applications. Unfortunately, the reliability of these modelling techniques is dependent on a thorough understanding of the performance characteristics of the components that make up the system. These characteristics include such things as response rate, hysteresis and efficiency. Some parameters such as idler rolling resistance can be easily quantified by measurement. More complicated drive parameters are difficult or impossible to measure, particularly in large horse-power equipment. One method of quantifying or at least bracketing the performance envelope of complicated pieces of equipment is to construct a mathematical model. This can be done quickly and economically, and the influence of various parameters can be determined. This paper sets out to demonstrate by example the usefulness of this technique in gaining an understanding of complicated systems. The model is developed and the influence of a number of variables are examined.

Jan 1, 1996

By Thomas R. Yanske, Jonathan E. Carmack, Lyndon M. Clark

In order to maximize the extraction of high grade pillars at The Doe Run Company, artificial pillars are created using cemented rock fill (CRF). CRF pillars aid extraction of pillars in two ways. One is to offer back support for the immediate area where pillars are being extracted. The second is to increase the post failure residual strength of pillars surrounded by backfill. The CRF is produced using a combination of minus 1.0 m run of mine (ROM) rock and minus 5 cm crushed rock. Depending on the operation the CRF slurry is either produced in an underground or a surface batch plant. The slurry and rock are transported to the fill area by truck where they are mixed and placed in 1 m lifts. To reduce the amount of CRF needed, fill fences are constructed around the perimeter of the CRF pillar. Within these fences ROM CRF is placed in lifts until within 0.6 m of the back after which minus five centimeter CRF is slung tight to the back utilizing slinger trucks. In constructing these artificial pillars a number of set procedures have been established to ensure that the work is done both properly and safely.

Jan 1, 2001

By Stéphane Servant, Jacques Ouellet, Ferri Hassani

This paper presents essentially the logistic and practical aspects involved for in situ testing of mine paste backfill with a self-boring pressuremeter. The investigation discussed in this paper is part of an extensive and ongoing research project to identify and validate an in situ testing technique for cemented mine backfill such as hydraulic or paste backfill as well as Insitu behavior of backfilled stopes. After a literature review on field testing of soils and past experiments on mine backfill in situ testing, the self-boring pressuremeter was selected as the most appropriate instrument for this task. The authors presents in this paper the technical aspect involved in a field trials that was conducted in a Canadian underground mine using paste backfill. The results of this first successful trials show that self-boring pressuremeter test can provide high quality and reliable backfill characteristics results, using analytical techniques developed for soils (Ouellet et al., 1998). The parameters obtained were: estimation of the lateral stress in the ground, the soil stress-strain response and the soil strength. The logistic and equipment required to conduct such testing underground is fully described. Performance achieved in the field and technical difficulties encountered are highlighted. Recommendations for future experiments with such instruments are given. Some potential technical improvements to better adapt this in situ testing technique to mine backfill are proposed.

Jan 1, 2001

By Victor S. Sazhin, Alexander Kostenko

The hydrochemical method, which is based on the separation of aluminium oxide and silicon oxide by the hydrothermal decomposition of aluminosilicates by alkaline solutions in the presence of calcium oxide, can be effectively used for the complex processing of high-silicon aluminium ores. In this case, the silica is bound to a slightly soluble compound: Na20.2Ca0.2Si02•H20 (under the conditions: [&k]= 9, CaO/SiO2 = 1.05, alkali concentration in the solution: over 300 g/l Na20, T = 240...300 °C). If alkaline solutions of 100...150 g/l Na20 concentration are used, Ca0•SiO2•H20 or 2Ca0•Si02.0.5H20 compounds, depending on calcium oxide dosage, are formed at 280...320 °C. New methods for the crystallization of Na20.Al203.2.5H2O from concentrated alkaline solutions rand low-concentration solutions are proposed to isolate aluminium from solutions. The hydrochemical method, which involves no sintering process allows one to decrease the expenditure of heat by a factor of two, to reduce the investment and to exclude the pollution of the ambient air by dust-laden gases. The expansion of the raw-material resources base of

Jan 1, 1984

By Alan G. Mayton, Jon C. Volkwein

The U.S. Department of the Interior, Bureau of Mines, in cooperation with an American firm, has been contributing toward the creation of a new highwall mining system for extracting coal in active, unreclaimed contour strip mines in the United States. The prototype system features the computer-based, remote control, video operation of a thin-seam continuous miner. Haulage is accomplished remotely also with a 76-m (250-ft) long multiple-unit continuous haulage (MUCH) conveyor system on rubber-tire vehicles. One aspect of this multi-faceted effort has been to design a ventilation system for removing dust generated at the face during the extraction process. The remote mining system eliminates the need for personnel in the mined workings. Ventilation is required to remove visible dust from the area inby two video cameras. These cameras are located approximately 6 m (20 ft) from the face, one on either side of a modified Jeffrey 102HP continuous miner. Removing the dust from this area provides the remote operator with constant visual monitoring of coal extraction at the face and thus, insures the effective operation of the mining system. A ventilation system was designed for use in a mine opening with a maximum cross-sectional area of roughly 4 sq m (44 sq ft) excluding the mining machinery. This paper describes the ventilation system and discusses how it was developed in view of the constraints imposed by the mining equipment, mining conditions, and the extraction process.

Jan 1, 1989

By D. W. Niosi

In this chapter, a review is made of the various stages of an exploration program, mineral rights acquisition methods and the partners involved in an agreement, the after- tax cash flow approach using present value discounting principles, the establishment of computerized financial models for assistance during the negotiating stages for a mineral property, and the various evaluation techniques and their specific applications during different phases of an exploration program. A set of examples is shown encompassing the initial target-seeking stages to the ultimate feasibility study stage.

Jan 1, 1979

By Charles E. Glass

As partial implementation of the Surface Mining Control and Reclamation Act of 1977, the Office of Surface Mining (OSM), Department of Interior, has requested each state to inventory hazardous abandoned mining areas within their boundaries. Primary interest is in such areas .as unstable waste-banks, subsidence and slumping, contamination of water supplies, and preservation of overall aesthetic qualities through reclamation. In addition to the concern expressed for abandoned mining areas, the legislation requires a complete inspection of operating mines quarterly and a partial inspection monthly. In Arizona copper has been mined for over 100 years and coal and uranium mining promises to expand in future years. The OSM requirement for a waste inventory and frequent monitoring of Arizona's large, widely spaced mines places a severe demand on limited personnel and operating budgets. Remote sensing by satellite provides an attractive and effective approach to aid the inventory and monitoring requirements of the OSM legislation.

Jan 1, 1979

By Fathi Habashi

WHILE HYDROGEN SULFIDE precipitates metal sulfides from aqueous solutions, other gases such as sulfur dioxide, carbon monoxide, and hydrogen, under certain conditions, precipitate the metals directly. This can be achieved at high temperature and pressure. Such processes are of great technical importance, since metals of high purity are precipitated economically in a powder form. As a result of the availability of such powders on a large scale. processes for compacting metal sheet and other mill forms directly from the

Jan 1, 1970

By T. C. Rao, N. Suresh, M. Vanangamudi

Experiments have been conducted on a 76¬mm water-only cyclone treating cowl below 2 mm size having different proportion of -0.075 mm fines. The effect of cone angle of the cyclone (compound cone) has been analyzed on water split, separation of -0.075 mm fines, separation of coarse solids, and on separation behavior of individual size ructions of the feed. It has been noted from the results that there exists a linear relationship between the flow rate of water in the feed and flow rate of water reporting to overflow stream. This relationship is independent of the cone angle and, with changes in the fines content in the feed, only the intercept of the straight varies, keeping the slope constant. Further, it has also been found that the percentage of fines below 0.075 mm reporting to the overflow is directly proportional to the percentage of feed wafer reporting to the overflow. This relationship is found to be independent of the cone angle and the fines in the feed. The performance of the water-only cyclone has been analyzed by plotting partition curves for different experimental conditions. In addition to this, the Rosin-Rammler equation has been fitted to the partition curves of the hulk feed and individual size-fractions. Tile analysis of the results has revealed that the specific gravity of separation increases with increase in the cone angle of the cyclone while it decreases with increase in percent fines present in the feed. Mathematical relationships have been developed to relate the variation in SG50 with cone angle and percent fines in the feed.

Jan 1, 1990

By Fathi Habashi

OXIDE ORES can be divided into two groups: 1) Simple oxides (Table 3.1). 2) Complex oxides. Those ores containing minerals composed of two oxides; an acid oxide (Cr2O3, Nb2O5, etc.), and a basic oxide (CaO, FeO, MnO), as shown in Table 3.2.

Jan 1, 1970

By V. Scovazzo

Cost-effective underground mine configurations have been designed in highly fractured rock masses where the stone possesses a high material strength. A limestone mine in the eastern United States is used to demonstrate procedures for the geotechnical design of one such operation. The mine discussed is located in both limbs and the axis of a recumbent fold that fractured the rock mass. In a highly fractured rock mass, where the host rock has high strength, a design can be developed to alleviate intact rock failure. This is possible because in most cases as the stress levels needed for intact failures are approached, the stresses are quickly dissipated due to movement along discontinuities, which represent planes of weakness. As a result most underground failures in highly fractured rock are due to sliding or toppling. Even when intact rock fails in a highly fractured rock mass, it is the movement along an existing joint or other weakness plane that often initiates or causes this failure. It is therefore important to obtain the characteristics of weakness planes that are the discontinuities within the mass. The required information on weakness planes, geology, and strength of materials is discussed and recommendations for obtaining this information are presented. A discussion is provided on failure modes and the use of developed information for their evaluation. The impact on geotechnical design is demonstrated through pillar sizing procedures; however, this approach can also be applied to mine roof and pillar foundations.

Jan 1, 2004