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Since 1955 Gaspe Mines has produced 144 million tonnes of ore, averaging 0.87% Cu, mined from two open pits and underground workings. In 1994, four exploration drill holes discovered a buried porphyry/skarn Cu-Mo deposit at depths of between 1000 m and 1700 m below the top of Porphyry Mountain. The mineralization and alteration associated with the Porphyry mountain quartz monzonite does not outcrop. A total of 19,500 m of drilling in 12 drill holes has outlined 200 million tonnes grading 0.73% Cu and 0.08% Mo. Mineralization occurs as veins and disseminations of chalcopyrite and molybdenite. Drilling and feasibility studies continue.

Jan 1, 1998

By Furuyama Takashi, Mori Sukeyuki, Hara Tsuyoshi, Fukushima Yujin

In mineral processing practice, flocculation is largely established as an engineering technique of waste water treatment and the study of parameters increasing the settling velocity of particles is still of great importance to improve the process. Further investigations were made using quartz (Q89) and fluorite samples (F91) which included 58.8% and 65.8% of -2.3 µm particles respectively. In all the experiments the flocculation phenomena were observed varying the pH value of the aqueous suspension. In contrast to quartz particles (Q89) which did not flocculate for all pH values, it was, noticed that fluorite particles (F91) flocculated in the alkaline range of pH over 11. With an aqueous suspension containing equal quantities of Q89 and F91, a hetero-flocculation of particles was observed at a range of pH below 10. In this case, the maximum floc size of the hetero-flocculation was 37.0-26.2 µm This size was about three times larger than when quartz (Q84) and fluorite particles (F85) were used with 32.4% and 40.4% of -2.31 µm particles respectively. Besides, in the experiments using Q89 and F91, the maximum size of hetero-flocculated single particles was found to be 6.54 µm instead of 3.27 µm as obtained with Q84 and F85.

Jan 1, 1995

By C. D. Elifrits

The required reclamation of land disturbed by surface coal mining often results in the creation of some over steepened slopes which are prone to rapid erosion and sediment production. This natural activity on such slopes is not desirable nor allowed under current regulations. Experience has indicated that novel approaches must be devised to address the problem. Research conducted on field sites in Missouri has indicated that construction, during the reclamation and grading processes, of a man-made drainage system will control the erosion. The drainage system must replicate or exceed the natural system in terms of drainage density and channel frequency. Basic design considerations will be summarized in this paper and field results shown.

Jan 1, 1986

By R. D. Hagni

Introduction The ore deposits of the Viburnum Trend in the Southeast Missouri Lead District constitute the world's largest lead producing district. Six or seven mines currently are in production in the Viburnum Trend. The principal minerals are few in number, simple in composition, and form simple superposition and replacement textures. The economically valuable minerals in the typical lead-zinc ores of the Viburnum Trend are the sulfides, galena, sphalerite, chalcopyrite, and siegenite. The most abundant gangue minerals are dolomite, marcasite, pyrite, calcite, quartz, and dickite. Four concentrates, lead, zinc, copper, and cobalt are produced from the ores, and they contain an interesting suite of trace elements, of which silver and cadmium are recovered at the smelter and refinery.1 Emphasis is given here to the variations in directions of ore fluid flow based upon interpretations of the positions of orebodies due to the ore fluids being impeded by Precambrian basement relief and upon patterns of ore mineral/metal zoning. The Precambrian basement relief and Lamotte Formation pinchout has exerted an important control upon the specific locations of orebodies in the Southeast Missouri Lead District. The locations of some orebodies along one side of Precambrian knobs or ridges strongly suggests that they are positioned on the side from which the ore fluids flowed. Other orebodies are located in positions that suggest that they formed where the ore fluids passed around or between Precambrian knobs. Patterns of mineral and/or metal zoning have been used in many mineral districts to interpret the directions of ore fluid flow. The mineral/metal zoning pattern correlates closely with that of the mineral paragenesis. The earliest deposited minerals tend to be deposited nearest to the source, the later deposited minerals next closest to the source, and the latest deposited minerals furthest from the source. In the Southeast Missouri Lead District, it is interpreted here that the early-deposited copper-rich ores are closest to the source of the ore fluids, the subsequently-deposited zinc-rich ores are next closest to the source, and iron-rich ores are furthest from the source.

Jan 1, 2006

By J. W. Lowry

After years of processing copper porphry ores, the Ray concentrator of Kennecott Minerals Company installed a concentrate regrind mill in its flotation circuit. The first cleaner concentrate is reground rather than the usual rougher concentrate. An additional cleaning of the reground product yields an increase in copper content of the final concentrate and a significantly lower insol content. The desired goal of decreasing the energy requirements for smelting the concentrate has been achieved.

Jan 1, 1980

By Michael Hood

Subsidence profiles above two adjacent panels in Illinois are compared with pro- files predicting subsidence behavior obtained using the (i) National Coal Board (NCB, 1975) method, (ii) the profile function method and (iii) the influence function method. The NCB method predicts the maximum subsidence values at the center of the troughs accurately, but, the overall shapes of these predicted profiles do not match the profiles from the measured data well. Consistent values for the angles of draw were measured but these angles were different in the transverse (average value 43 degrees) and in the longitudinal (average value 17.5 degrees) directions. Time dependent subsidence effects are shown to be small but measurable. These displacements continue at a linear rate for at least a 12 month period. A comparison of measured horizontal distances, interpreted as horizontal strain, and the NCB predictions for strain shows that the peak measured strains are greater by a factor f about four than the predicted strains. The relationship between surface curvature and strain is investigated. Problems associated with calculation of surface curvatures from vertical displacement data are highlighted and a recommendation is made for future studies to consider direct measurement of this parameter. Surface curvatures above a moving face are found to be about three times less than the curvatures at the stationary end of the panel. On the other hand, a hyperbolic tangent profile function is shown to serve as an accurate predictive tool for subsidence behavior in two adjacent longwall panels at Old Ben Number 24 mine in Illinois. This function predicts not only the vertical displacements but also the surface curvatures above both panels. Influence functions are shown to be more problematic, although potentially more flexible, in their application than the profile functions.

Jan 1, 1982

By K. E. Burgher

Since World War II, the need for the use of explosives in construction, mining, and quarrying near congested urban areas has increased dramatically. Often times a coal mine, once isolated from a city, finds itself surrounded by residential and commercial structures. The United States Bureau of Mines and others have researched blast design to a point where ground vibration and airblast damage can be avoided. A problem still exists, however. It is the fact that people often react to only the loud noise associated with a blast although it may not cause damage. Most often it is the concussion of a blast, less than 20 hertz and inaudible, that produces damage. Public fear from the "startle" and "fright" of loud blast noise greater than 20 hertz leads to the complaints which are generally unfounded. See Thackray, Touchstone, and Baily (1975) for a further discussion of the startle effects of loud sudden noises. When blasts are designed in accordance with U.S.B.M. specifications, management generally has little to worry about with respect to damage claims. Complaints, however, still arise when the noise is accentuated from the blast. It is meteorological conditions which dictate how the sound levels will propagate. Some mines use small pilot test shots (generally one-two lbs) to determine when atmospheric conditions favor sound travel.

Jan 1, 1987

By J. G. Jenkins

Magma Copper Co.'s San Manuel solvent extraction/electrowinning (SX-EW) facility has operated since May 1986. The original facility had a design capacity of 22.6 kt/a (25,000 stpy) of electrowon copper cathode produced by processing pregnant leach solution from an open pit-heap leach operation. In 1988, the plant was expanded to 45.3 kt/ a (50,000 stpy) to incorporate processing in-situ leach solutions. This pager focuses primarily on the heap leaching area with regard to exploration, testing, feasibility, permitting, design and construction, and operating practices. Research using surfactant leaching aids to enhance copper recovery is also discussed.

Jan 1, 1995

In 1991, most industrialized countries, except for Germany, were in a recession or a period of reduced growth. The US economy, already in recession, suffered from mounting banking system losses and the uncertainty brought about by the Persian Gulf War. However, US and worldwide minerals exploration did not collapse as it did during the mid-1980s. Even though gold and base metal prices declined, prices were still above cash costs for most operations. This allowed the continuation of established exploration programs but sharply limited new initiatives. Exploration 1990-1991 Planned worldwide 1991 exploration expenditures declined by about 8% from 1990 levels, according to a survey of 153 companies by the Metals Economic Group (MEG). Canada was the leading exploration target with 23% of the total, followed by Australia and the US (19% each), South Africa (13%), Latin America (11%) and the South Pacific (7%). The remaining 8% was split evenly between Europe and the rest of Africa. In Latin America, Mexico and Chile are the most attractive countries for exploration. Recognizing the risks involved, the industry has been cautious about ventures in the former Soviet Union. Survey results also showed that while the majors expected to maintain exploration spending, smaller firms were cutting back or actively seeking farm-outs from the majors (personal communication, M. Wegener, MEG).

Jan 1, 1992

By William E. Cutcliffe, John A. Ames, John D. MacFadyen

Webster's dictionary nearly equates portland cement with its current primary definition of cement. Although such equation may be a triumph of common usage, the confusion between the terms cement and concrete unfortunately is very widespread. Full definition of cement properly would extend to many substances, but for purposes of this chapter cement is restricted to varieties of portland cement including portland-pozzolan cement. Among the usually recited historical notes concerning cement is that it was developed by the Romans. Their use of cement in the great structures of Rome, and even in the far comers of their Empire, such as Hadrian's Wall in the north of England, testifies to the antiquity of a major cement industry. From English sources we know of John Smeaton's carefully proportioned hydraulic cement mixed in 1756 and of Joseph Aspdin's patented cement to which, in 1824, he gave the name portland cement. (He claimed that his cement mortar looked like the famous dimension limestone quarried from the Isle of Portland on England's south coast.) The year 1971 marked the centennial of portland cement manufacture in the United States. A fair historical account of the many real contributors to the cement industry since 1756 unfortunately would be too extensive for this chapter. Development of rotary kiln practice and burning at higher temperatures clearly was the major move into today's technology. Cement manufacture is the processing of selected and prepared mineral raw materials to produce the synthetic, mineral mixture (clinker) that can be ground to a powder having the specified chemical composition and physical properties of cement. Cement making incorporates a number of distinct steps, but it is characterized by the key pyroprocessing (or burning) step, which brings about the necessary changes in the raw materials. This pyroprocessing is a chemical process. Conversion of large volumes of mineral raw materials into specification-controlled cement at relatively low cost is the objective. Statistics on the cement industry are of uneven quality. The US Bureau of Mines (USBM) is the principal collector of available data. These statistics can be only as good as the quality of information supplied by the reporting companies. The data perhaps most often questioned relates to productive capacity of the industry. The questions submitted by USBM are valid, nevertheless, and the information gained from them, as good as is available, is what is generally used. The Portland Cement Association also is a source of much quality information. In analyzing cement industry production rates, it is well to keep in mind that measurement of raw materials requires the reader to recognize that approximately 1.6 t of dry raw materials are required to make 1 t of clinker. This number can vary depending on the amount of kiln dust wasted. Also that to produce 1 t of portland cement required .94 to .96 t of clinker, the remainder being gypsum or anhydrite. A ton of masonry cement or pozzolanic cement re- quires considerably less clinker.

Jan 1, 1994

By German Zambrana

The solution of the problem of beneficiation of cassiterite from its primary ore deposits is of fundamental importance to Bolivia. The process today involves a gravimetric treatment of the ore followed by sulphide flotation. During the last year, a cassiterite flotation stage has been added in several plants to treat the slime tailings. Although cassiterite flotation is already economical for the slime tailings and the mechanism of the process are understood, it is felt that further research could improve the results. In the past, considerable amount of research and test ark has been performed to select appropriate collectors to improve recovery, to increa¬se the grade of tin in the concentrate, to minimize the effect of metallic ions like Ca+2, Fe+2 and Fe+3 which prevent flotation, and to increase the pH of the pulp which now it can not be higher than 3.0. It has been reported that the halogen salts (1) like NaCl exhibit special surface affinity for cassiterite but none for quartz. These effect seems to be favourable for the selective flotation of cassiterite from silica minerals. In view of these preliminary results it was decided to follow the research accordingly: OBJECTIVES The objectives of the present investigation are: 1. 0 evaluate the influence of NaCl salts in quartz and cassiterite flotation.

Jan 1, 1971

By P. L. De Bruyn

[According to the Young equation, SG = SL + Coso, the equilibrium contact angle depends on the values of the three interfacial tensions involved. A solute promotes wetting, i. e. a decrease of contact angle if it decreases.LG and/or YSL or if it increases SG. Dewetting, the important step in flotation is, promoted if the solute increases y and/or SL or decreases. Most solutes used for wetting or dewetting are, positively adsorbed at all interfaces involved and consequently according to the Gibbs equation lower the interfacial tensions. Wetting is therefore expected to occur if LG and SL are more affected by the solute than SG. Dewetting on the other, hand demands a greater decrease of SG than that of SL (and of LG). See P. L. de Bruyn, J. Th. G. Overbeek and B. Schuhmann, Jr., Mining Engineering (1954) P. 519.]

Jan 1, 1960

By C. Cigna, M. Patrucco, D. Savoca, E. Lovera

The paper deals with the activity program and the preliminary results of a research work commissioned by IReR Research Centre and Regione Lombardia to the Department of Land, Environment and Geotechnologies of Politecnico di Torino. The aim is to define measurement, analysis and control criteria for the emission of chemical and physical pollutants from non-metal mining industries, with particular reference to noise and airborne particulates. Such emissions are related to health risks and annoyance problems, both for the working crews and the neighbouring population, and so, in order to get an effective sustainability of the industry, suitable reduction methods and assessment tools are required. A simple technique for the evaluation and forecasting of both the emission levels and deriving impact has been tested at different mining and quarrying sites, considering their differences in terms of layout and exploitation method, the latter ascribed to a series of main typologies as present in Lombardia region.

Jan 1, 2005

By L. F. Ruppert, R. C. Milici

Coalbed methane (CBM) is currently being produced from a relatively small area in the Dunkard and Pocahontas basins, in the northern and central parts of the Appalachian Basin, respectively. In general, much of the production occurs where the coal beds are beneath 500 feet or more of overburden, where the rank of the coal is high-volatile B or greater (%Ro >0.8), and where the natural fracture system is enhanced by structural deformation. It is anticipated that near-term CBM development will continue within these areas and will expand in the Appalachian basin as technology improves and as the price of gas rises.

Jan 1, 2003

By Thorvald Wetlesen

Computer controlled drilling is now proven technology. It was first introduced by the development of the Furuholmen system for a prototype three boom tunneling jumbo in Norway in 1978. Now, 13 rigs with this concept are in operation in Europe, 3. in mining in England and. 10 in tunneling elsewhere in Europe. The system is also adapted to roadheader guidance. Practical experience has shown that the computer control system makes it possible to drive tunnels with a more accurate contour thus reducing the total amount of rock excavated, and where a full concrete lining is required a reduction in concrete volume is achieved. The total tunneling economy is improved. In the future we expect to see a wider range of instrumentation on jumbos, from the simple direction instruments to computer guidance systems for monitoring only, as well as fully automatic drilling to a programmed drilling pattern. More compact and reliable electronics will be available. Systems with low power consumption will fit easily into flameproof applications. Cabling complexity will be reduced by connection of sensors to serial signal lines.

Jan 1, 1989

By d&apos, L. F. G. Assumpcao

Kaolin samples from Rio Capim resources were treated in conventional and superconducting magnetic separators to study the main variables that influence the color removal process. Coating clays and delaminated clay were tested. Retention time (or pulp injection velocity), magnetic field intensity and matrix type were the' variables studied. The feed brightness ranged from 84.7 to 87.6 % ISO for the coating clays and from 80.7 to 85.4 % ISO for the delaminated clay. The results showed unleached brightness values higher than 88 % ISO for coating products and higher than 87 % ISO for the delaminated product, using a conventional magnetic separator with an applied field of 1.5 to 2.0 Tesla. With a maximum field intensity in the superconducting machine of 5.0 Tesla, unleached brightness values higher than 88.5 % ISO for both coating and delaminated clays were attained.

Jan 1, 1995

By M. J. Virnig, Christopher A. Fleming

THE CIP PROCESS "IN THE RIGHT PLACE AT THE RIGHT TIME? After its tentative introduction to the precious metals mining industry in the earlier part of this century, the carbon in pulp (CIP) process has now come of age, and is the process of choice on all new gold mills. Well over 50 percent of all gold that is mined each year is recovered by adsorption on activated carbon, and the percentage will increase in the years ahead, when old mills using Merrill Crowe technology come to the end of their lives, and as the proportion of world gold production from low-grade resources increases. The pioneering process development work in this field, which was mainly concerned with carbon elution, was carried out by Zadra and his colleagues at the United States Bureau of Mines in the early 1950's (Zadra et al., 1950, 1952), and led to the commissioning of the first large-scale, industrial CIP plant, at the Homestake Mine in South Dakota, in 1973 (Hall et al., 1974). From there, the process spread rapidly, firstly in South Africa in the late 1970's. and then throughout the rest of the gold producing world in the 1980's. There were several factors that led to the meteoric (by gold industry standards) acceptance and successful implementation of this new technology into gold processing operations worldwide. Firstly, and perhaps most fortuitously, the development of the technology closely paralleled the 1968 release of the gold price from the rigid constraints of the $35/oz. gold standard. With the value of the metal allowed, for the first time in modern history, to fluctuate in response to free market supply and demand forces, the gold industry witnessed an unprecedented boom as the price of their commodity increased ten-fold in a remarkably short period of time. This had several important spin-offs as far as new process developments were concerned: The profits realized by established gold-mining companies increased enormously and, consequently, there was more to spend on research and development and exploration for new deposits.

Jan 1, 1993

By J. P. A. Hortley

In conventional electrolytic copper production, looped copper starter sheets, on which the copper is deposited, are supported by hard-drawn copper bars. These bars have cross-sectional areas of between 1 and 1.4 in2. The suspension bars serve two purposes: firstly to support the cathode, which can weigh up to 150 kg, and secondly to introduce the electric current. IYI examined these two requirements in detail to see whether a better design could be achieved. Considering firstly the current carrying requirement, it wee noted that under normal refinery conditions, each cathode carries between 400 and soak. If one applies the generally accepted rule that 1 in of copper can carry 1000A4 a suspension bar need theoretically contain only 1/2 in2 of copper. This contention is supported by the fact that the 500A current passed through the cathode also appears to pass quite satisfactorily through the two support loops, which have a cross-sectional area of approximately 0.35 in 2. Turning now to the strength requirements, the cross-section of hard-drawn copper bar required to support a 150 kg cathode is relatively small, and easily met by the present designs. It is not, however, the static load applied by the 150 kg cathode immersed in the electrolyte which causes the damage to the hard-drawn copper, or even the increased static load of a 100 kg man standing on one foot in the centre of the bar; the damage is actually caused by the dynamic loads applied to the bare when they are dropped, thrown into containers, lowered too rapidly into the cell, or otherwise mistreated. The important requirement is therefore that the bar does not permanently bend. Its proof stress of limit of proportionality, rather than the amount that it deflects under static loading, should be the strength criterion. With the hard-drawn copper normally used for the manufacture of suspension bars, it has been observed that the copper becomes annealed during use, particularly at the end of the bar where the current is introduced. Thus, after a relatively short time, the cathodes are in effect being supported by annealed copper bars.

Jan 1, 1978

By C. P. Lazzara, F. J. Perzak, C. C. Hwang, C. D. Litton

Fire development and spread along conveyor belts in ventilated ducts were investigated experimentally and theoretically. Various types of conveyor belts used in mining applications were ignited and burned in a full-scale gallery under various flow conditions. The flame spread rates depended strongly on the ventilation air speed. The time-temperature traces of gas and belt obtained at 12 feet from the entrance show that a rapid belt surface temperature change takes place prior to a change in the gas temperature, indicating that radiative heat transfer from the flame to the belt surface plays an important role. Further, anomalies in the flame spread rate in the vicinity of 1.5 m/s air speed (i.e., much greater rate than that observed at either higher or lower speeds) can be explained through the mechanism of flame tilt and the resultant view factor between the flame surface and the belt surface. In order to correlate the fire spread with material properties of the conveyor belts (such as the specific heat, the thermal conductivity, and the pyrolysis temperature) and the fire environment (such as the gas temperature and the ventilation air speed), a theoretical model has been developed. This model is based on the experimental observation that the radiative heat transfer is the dominant mode of energy transfer ahead of the flame front. Agreement between the theory and the experimental results is good.

Jan 1, 1991

By S. K. Kawatra, K. A. O, DeLa&apos

On-line sensors and process controls are important for efficient operation of coal preparation plants. The objective of this paper is to describe the current practice in on-line measurement of composition, density, moisture, level, flow and weight. This paper also discusses how on-line sensors can be implemented in process control, and how sensors which are currently being developed can be utilized.

Jan 1, 1988