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By G. O. Kesse

The Republic of Ghana, located on the West Coast of Africa, is one of the West African countries rich in bauxite deposits. The main occurrences of bauxite deposits are at Sefwi Bekwai in the Western Region, Aya-Nyinahin in the Ashanti Region, Atewa Range near Kibi and at Mount Ejuanema both in the Eastern Region of Ghana. These bauxite deposits belong to the so-called blanket deposits as they are associated with erosion surfaces of old peneplains and occur as cappings on the flat tops of hills or mountains whose heights are generally greater than 600 metres above sea level. These deposits can also be classified as laterite-silicate bauxites since they have been formed under tropical weathering conditions. Genetic and mineralogical investigations have revealed that all bauxite deposits of Ghana are the result of indirect bauxitization processes, for the minerals of the weathering parent rocks have not been transformed directly into gibbsite. In all cases, lithomarge of kaolinitic clay can be recognised. The geology of the major occurrences of bauxite in Ghana shows that the Mount Ejuanema deposit is the only deposit associated with the Voltaian System of rocks. This rock System consists mainly of sandstone, shale, mudstone, conglomerates and pebbly beds. All the otter deposits are associated with the Birimian System of rocks which are made up of metamorphosed lavas,pyroclastic rocks, hypabyssal basic intrusives, phyllites, schists, tuffs and greywackes.

Jan 1, 1984

By S. A. Voltura

The Phelps Dodge Miami smelter has smelted copper concentrate using the ISASMELT technology since 1992. The design throughput rate was 591,000 tonnes/year and after a slow start-up, the production rate has exceeded the design after the seventh year of operation. In 2002, the smelter consumed 719,000 tonnes of copper concentrate and has the potential to hit the permitted rate of 772,000 tonnes/year. Improvements to the smelting vessel and the surrounding support processes have allowed for continuous improvement from start up until now. This presentation will outline the chronological events and the improvements completed to accomplish these improvements

Jan 1, 2004

By D. Royston

Curved pulp lifters can provide improved discharge performance from SAG mills, especially for the coarser fraction of rocks in the discharge. They also can provide improved wear life of the pulp lifter, especially the base of the pulp lifter and diversion cone, over comparable straight radial pulp lifters. Current experience with curved pulp lifters and associated grates is covered including design issues and discharge performance for both the slurry and rock components of the discharge.

Jan 1, 2003

By Chi M. Phan, Anh V. Nguyen, Geoffrey M. Evans, Graeme J. Jameson

Surfactants are used to control the interfacial properties of the gas-liquid and liquid-solid inter- faces inflotation. This paper investigates the dynamic adsorption of surfactants at the gas-liquid intelface. The dynamic adsorption process was modeled by considering the surfactant mass transfer to the gas-liquid interface by dimion and the Langmuir and Frumkin adsorption isotherms. The numerical computation was applied to solve the non-linear governing equations. The dynamic adsorption was measured in tenns of the dynamic surface tension using the pen- dant drop method. The theoretical modek were compared against the experimental data obtained with non-ionic (Dowfroth 250) and ionic (sodium dodecylbenzene sulfate, SDBS) surfactants. The theoretical results agreed well with the erperimental data for SDBS, but not for Dowfrother 250, especially for the initial stage. Reasons for the variation in results are given in the paper.

Jan 1, 2005

By A. Unal, R. L. Grayson

The use of radio frequency identification (RFID) technology to solve informational needs in isolated and restricted underground mining environments are reviewed, and the specifications of some of the past and currently available systems are presented. The advantages and disadvantages of using various frequencies, system configurations and specific components, including their construction standards and capability, are also discussed. The remaining challenges to the more widespread use of RFID systems for personnel and vehicle tracking are identified, and recommendations concerning the operating environment capabilities are detailed. Finally, the ultimate requirements for maintaining system integrity during and following a coal mine emergency are discussed.

Jan 1, 1999

By B. G. Long

Coastal States Energy Company (Coastal), a wholly-owned subsidiary of The Coastal Corporation of Houston, Texas, owns coal mining operations in Utah and Kentucky. One of the Utah operations, Southern Utah Fuel Company (SUFCo), located 30 miles west of Salina, Utah, has been operated by Coastal since 1974. This operation is a single-seam, six-section mine operated from one portal area. It produces 2.2 million tons of coal per year and has a payroll of approximately 300 employees, Coal is mined by continuous miners, hauled by diesel-powered haulers and transported by belt conveyor to outside crushing and screening facilities. Sized coal is hauled by contract truckers 80 miles to a unit-train facility located at Levan, Utah.

Jan 1, 1983

By Dale R. Ralston, Roy E. Williams, Gerry V. Winter, George L. Bloomsburg

The purpose of this section is to demonstrate the development of a method that we believe can be used for simulating and predicting mine water inflow. It will also show how important it is for personnel who model mine water inflow to have considerable experience with this subject, and with the conversion of hydrogeologic frameworks to conceptual models. Several of the models described previously are said to be three dimensional. However, closer examination reveals that there is considerable limitation in the variation possible in the third dimension. A true three-dimensional analysis would require a very large program. Therefore, it seems more reasonable to develop a procedure by which information from a two-dimensional model can be used for analysis of a three-dimensional problem. For a vertical mine shaft this is relatively easy because most two-dimensional models have an option for axisymmetric flow. If it can be assumed that axisymmetry exists about the centerline of the shaft it can be modeled easily as has been illustrated previously. For a horizontal drift or tunnel the analysis is not nearly as straightforward. However, the flow can be divided into two parts as indicated in Fig. 59. Part 1 considers the flow into the side of the drift while part 2 considers the flow into the end of the drift. To calculate the flow rate into the entire drift from the unsteady flow into a unit length the instantaneous flow per unit length may be integrated over the total length of the shaft. This procedure is shown in Fig. 60. The radial flow through any incremental length of the shaft is q. The total flow rate, Q, into the drift at any particular time is given by: The discharge q is a function of the time during which a particular segment has been draining that is dependent on the location x. In other words, a location at x = 0 has been draining during the entire time of expansion while a segment at x = L has only started to drain. Therefore, the time of draining at any point, x, is given by: [ ] where t' is the time over which the mine has been expanded. To determine the relationship between q and t it is necessary to refer to Polubarinova- Kochina (1962, pp. 566-569) and the equation given for the unsteady flow problem. This is: [ ] where q is the steady flow, q,, q, are the coefficients, and t is the time since drainage began. The expressions for q0, q1, and q2 are given as:

Jan 1, 1986

By Young C. Kim

Determination of the minimum sampling requirements of the run-of-mine (ROM) coal is very important for the purpose of meeting contract specifications. It is also important for the purpose of meeting emission regulations at a coal-burning power plant, such as the one located at Homer City, Pa. The classical statistical sampling theory can be applied to this problem, if ROM coal samples are known to be spatially (or serially) uncorrelated. On the other hand, the estimation variance concept from the Matherson's geostatistics must be used, if the samples are spatially correlated. Conditional simulation technique combined with simulation of the existing mining method is used to determine under which circumstances ROM coal samples do not preserve the spatial correlation. Only after establishing the degree of correlation that exists among ROM samples, an optimal sampling scheme can be devised using either the classical statistics Or the geostatistics. The minimum required sample volume can then be calculated using the well-known Gy's formula. This paper describes the results of the above investigation using the Helen coal mine data of the Homer City Owners. Empirical guidelines for determining the degree of correlation are also provided for coal mine operators.

Jan 1, 1986

By Paul Saxton

INTRODUCTION AND SUMMARY This short paper deals with the history of the Nickel Plate Mine from 1898 to 1987, with the major focus on the time period 1984 to 1987. Operations from 1898 to 1955 are reviewed in a cursory manner with the emphasis on some interesting points in the early 20th century. A review of the major exploration work carried out in 1984 to 1987 is presented and the process of moving the project through feasibility, government permitting and construction is described. The Hedley gold camp is situated approximately 40 kilometres east-southeast of Princeton, in southern British Columbia. The area has had a long history of gold mining and between 1902 and 1955 approximately 1.5 million ounces of gold were won from several mineralized skarn orebodies. Most production came from the Nickel Plate and Hedley Mascot mines. AN EARLY TO MID 20TH CENTURY SUMMARY The Nickel Plate is one of the oldest mines in the province. The mine had operated from 1904 to 1930 and, after a period of shutdown, from 1934 to 1955. The mine was revived in 1967 for exploration and. will resume production during the first half of 1987. In the first period the Yale Mining Company and Daly Reduction Company operated for six years and Hedley Gold Mining Company for twenty-one. In the second period the mine was operated by the Kelowna Exploration Company Limited and Kelowna Mines Hedley Limited for twenty-one years. In the present period the mine has been revived by Mascot Gold Mines Limited.

Jan 1, 1987

By J. R. Stoltz, E. Thompson, S. Pattee

On May 15 and 16, 1999, a mine ventilation survey was performed in the 705-m- (2,312-ft-) deep Cayuga Mine, Cargill Salt Division, Lansing, NY. The purpose of the survey was to develop a numerical model of the existing ventilation system and to perform a computer simulation study for long-term environmental and ventilation planning. Because the natural ventilation pressure (NVP) has significant effects on the ventilation system at the Cayuga Mine, there was a need to assess the NVP acting in the mine. Due to the ventilation arrangements in the Cayuga Mine, the authors decided to use the direct-measuring method to determine the NVP by measuring differential pressure across the automatic fan door. This difference in pressure was measured immediately after the fan was stopped and the automatic door was closed to stop the flow throughout the entire mine. To show seasonal changes in NVP, two additional measurement for NVP were performed, one on Aug. 22, 1999, during the hot (summer) season, and another on Feb. 6, 2000, during the cold (winter) season. The mutual interaction between the natural ventilation pressure and the main fan at the Cayuga Mine is also discussed

Jan 1, 2003

By S. Mathur

The southern Florida phosphate deposits that will be mined in the future contain significant amounts of dolomite. Because high MgO levels are undesirable in phosphoric acid production, several flotation schemes for the removal of the dolomite have been attempted. Alternatively, selective flocculation has been suggested as a potential process. A high MgO rock was simulated with a 30:10:60 mixture of apatite, dolomite and silica, respectively. Single mineral selectivity was observed in the apatite-silica and dolomite- silica systems using Polyacrylic acid (PAA) and Poly(ethylene oxide) (PEO) flocculants, respectively. However, no single mineral selectivity was observed in the apatite-dolomite system using PEO. Heteroflocculation, suspected to be the major reason for the loss of selectivity, was minimized by the addition of a site blocking agent (SBA), consisting of a lower- molecular-weight fraction of PEO. Process parameters such as size reduction schemes, flocculant/SBA dosage and pH were investigated to achieve the desired separation. The selectivity obtained in binary mixed-mineral tests was also achieved in the ternary mixed-mineral system, namely, the apatite-dolomite-silica system. In this report, surface chemical characterization of the samples and their flocculation behavior are discussed.

Jan 1, 1995

By A. Bleier, E. D. Goddard, R. D. Kulkarni

The influence of the collector structure on the amine (RNH2, R=alkyl) flotation of quartz has been systematically investigated using a modified Hallimond microflotation cell. This study focuses on the effect of varying chain length, branching in the alkyl group R, polyfunctionality of the collector molecule, and alkyl substitution on the nitrogen atom. In addition, adsorption at the solution/air interface and electrokinetic results for the solid/solution interface were employed to further elucidate the role and the interrelation of the structural parameters in the flotation process. Estimates of an electrical double layer attractive energy between the bubble and the solid particle are made.

Jan 1, 1976

By S. Triantafyllidis

The tailings produced from the Kirki (Agios Filippos) high sulfidation epithermal deposit processing plant are laminated, weakly cemented and their particle size ranges from fine sand to fine silt. They are mainly composed of milling residues of gangue (quartz, dickite/kaolinite, pyrophyllite, illite); sulfides and secondary minerals (jarosite group minerals, butlerite, anglesite, beudantite and gypsum) are present to a lesser extent. They have high Pb and Zn (average 0.75 % and 0.57 % respectively) and low S (1.04 to 2.92 %), Cu, As, Cd, Ni and Sb content (average 248, 163, 59, 27, 20 g/t respectively). Stagnant waters forming small ponds on the surface of the impoundments exhibit low pH and high heavy metal and sulfate concentrations. Negative Net Neutralization Potential (NNP) characterizes the tailings, indicating moderate to high potential for acid generation. Application of the TCLP test revealed that the tailings are characterized as toxic because of the increased solubility of Pb and Cd. On the other hand, As TCLP solubility is very low.

Jan 1, 2006

By Judith A. Marks, Deane K. Smith, Jan M. Mutmansky, Maria Klimkiewicz

The mechanical mining of coal seams where roof, partings, and floor rock are extracted along with the coal often introduces large numbers of quartz particles into the mine atmosphere. This study concentrates on the quartz properties in situ and in the airborne dust to determine how they are released from the source rock and whether they are fractured by the mining machinery. Three mines using drum-type continuous miners from different geographic areas were sampled to provide a data base. The roof and floor rocks were primarily siltstones containing 5% to 25% quartz measured by the X-ray powder diffraction (XRPD) method. Much of the work presented here is based on the morphologies of the mineral grains determined by the scanning electron microscope (SEM). The study concentrated on particles of 0.2 to 10.0 µm and on particles containing > 75% Si. Mechanically-crushed quartz particles were also examined for comparison purposes. Particle shapes from the airborne samples suggested that fractured quartz particles were rare. Particle statistics also show that the average size of quartz particles in the airborne samples were similar to the average size of all particles. The conclusion is that very few quartz particles from the source rocks are fractured during mining due to their small initial size and the protection of the associated clays.

Jan 1, 1991

By Anitava Ghosh

A computer program has been written to simulate ground vibrations induced by multiple- hole surface blasts. The program is an inexpensive and relatively easy to use tool for predicting the principal blast vibration characteristics that determine damage and annoyance potential: peak particle velocity, frequency content and pulse duration. The program generates a complete ground motion history by superposing, at any surface position, the vibrations induced by each individual explosive charge. It requires specification of (hence allows accounting for) the blast geometry, initiation sequence (including random delays), position with respect to blast, pulse characteristics induced by each charge, and propagation laws. A methodology is outlined to determine the necessary variables either on the basis of site investigations (e.g.,velocity, attenuation, single-hole input pulse), or by back-calculation from measured blast vibration records. The latter procedure has been applied to blasts from two coal strip mines. Main difficulties encountered are backcalculating individual input pulses, propagation (especially dispersion) parameters and delays. A normal distribution of delays, based on published results, has been shorn to influence the results and the response of a single degree of freedom structure significantly. Broadening of the wave types included, improved input pulse determination and propagation laws, and more detailed verifications with field results are required in order to make the program more directly applicable to practical situations.

Jan 1, 1986

By R. F. Al-Fariss

The phosphoric acid industry is expected to develop in Saudi Arabia in the near future. There are three main reasons for expecting this: the discovery of phosphate deposits in the Sirhan-Turayf region, the construction of phosphate fertilizer facilities of the TSP, DAP and NPK plants on the east coast of the country, and the availability of an ample amount of sulfur As a by-product from the petrochemical industries. This study is a part of the research work performed in the chemical engineering department At King Saud University to evaluate the Saudi phosphate rocks for the wet process phosphoric Acid production and to test different flotation methods for the carbonate rich phosphate rock In a laboratory scale flotation cell. Experimental results for the above tests, as well as Beneficiation by calcination, are presented.

Jan 1, 1993

By T. Malterer, R. Adams

Peat has unique physical, chemical and biological properties. These include high porosity and water retention, high absorption and adsorption properties, and high buffering capacity. In addition, peat is a rich medium for microorganism activity. Peat has traditionally been used for horticultural purposes. However, in recent years, peat is increasingly being used for waste- treatment purposes. This paper reviews North American literature on the use of peat for waste-treatment applications. The literature indicated that peat has potential for use in the treatment of municipal and on-site effluents, for the removal of low concentrations of heavy metals and for the adsorption of liquid and gaseous hydrocarbon pollutants.

Jan 1, 1997

By Fathi Habashi

THE CHOICE of a precipitant for a certain metal ion depends, beside the economic factor. on the following factors: 1) The precipitant should be specific as far as possible so that pure precipitates can be obtained

Jan 1, 1970

By Patrick Hannon

In this presentation, it is intended to briefly describe some occurrences of lead-zinc mineralization in Mississippian carbonates of central Nova Scotia. Results of geophysical and geochemical prospecting are presented. Because the deposits do not give positive identification to these indirect techniques, it is necessary to site exploratory drilling through the development of geological concepts.

Jan 1, 1975

By José Salim, T. V. Subrahmanyan

The occurence of primary stratiform and vein gold deposits in the Precambrian rocks of Northeastern Brazil is discussed. The stratiform deposits are related to clastic sediments (quartzites and conglomerates). The veins are associated with quartz and sulfides and are structurally controlled by shear zones. The gold was recovered for a long time by small miners. Developmental programmes for large scale mining are now envisaged. The recovery problems and gold economics are also discussed.

Jan 1, 1988