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By R. S. Das, A. K. Sinha

Modern mine ventilation systems have grown rapidly in recent years both in terms of complexity and value for human health and safety. Although computer models are now available to help the design and operation of mine ventilation systems, considerable differences often exist between the computer-based predictions and practical results. Research conducted to compare computer results with practical measurements made in ventilation circuits simulated in a physical model seems to confirm such differences. It is concluded that although a mine ventilation computer model is a very powerful tool, it can be utilized to its full potential only if reliable input data are provided.

Jan 1, 1987

By L. A. Puchkov

The creation of automatic methane concentration control systems presupposes the use, as a control factor, of the air rates in workings and in mine as a whole. These systems present a complicated set of computers and software, including as major components the following - systems for detecting methane concentration and air rate; - telemechanics systems; - programs and means of data processing; - programs and means of air rate control in workings and main fan capacity control. The paper analyses the experience of development and exploitation of automatic methane control system in gassy mines of the USSR Donetz coal basin. Much attention is given to the study of technological factors influence upon aerogasdynamic process using automatic methane control system.

Jan 1, 1989

By C. R. Bennett

A copper heap leach model, employing leading edge computational fluid dynamics (CFD) technology, is applied to the Zaldivar heap leach operation in Chile in order to explore and analyze the possible impact of operational changes. The effect of changes to the heap operation on copper recovery has been previously investigated and reported by the Zaldivar operation. This paper examines the extent to which a comprehensive heap leach model supports the analysis and conclusions of the published work. The heap is a complex multi-phase process, consisting of a solid static porous media with complex fluid flow, gas and liquid phases, competing solid-liquid reactions, dissolution of minerals and transport through the heap. The model accounts for the physical and chemical features of the heap, including transport and reactions kinetics for the important copper and iron sulfide minerals, ferrous oxidation, bacterial effects, thermal energy, acid and sulfate balances. The model was calibrated to published data on the ore body and employed to analyze the impact of a number of operational changes, including solution flow rate, acidity, lift height, crush size and head grade.

Jan 1, 2012

By Jess H. Albino, Girish Roy, James M. Monsees

Construction of the North Hollywood line of the Los Angeles Metro System required crossing the Hollywood Fault as the twin transit tunnels extend into the San Fernando Valley. The Hollywood Fault is considered active and represents the largest active fault that the North Hollywood Redline extension will cross. The feature is a thrust fault with the north plate overriding the southern plate and creating the Santa Monica Mountains in the process. South of the fault lies the alluvial valley and Hollywood. North of the fault are the Santa Monica Mountains which rise locally to more than 1200 feet. The average overburden at the seismic section is about 300feet and is overlain by Runyon Canyon Park, a municipal park with environmentally sensitive areas. The actual fault plane was anticipated to lie within the southernmost120 feet of the 600 to 700-foot-wide fault zone. The special seismic section constructed for the tunnels consisted of an enlarged cross-section with special lining, drainage and finish features that will facilitate the restoration of metro service in case of a major event occurring on the Hollywood Fault. The discussion will address the geology, the procedure used to define the design event and predicted displacements, the unique design features as well as the construction methods used and the instrumentation and the results obtained.

Jan 1, 1999

By R. Hogg, T. F. Dumm

A simple shape description scheme has been developed which has the specific aim of distinguishing between angular and more rounded particles. The procedure involves fitting a general polygon (usually about 20 sided) to the particle profile. Geometric shape descriptors have been defined based on variations in the angles between adjacent sides and their radial displacement from the particle centroid. A two-parameter shape description, incorporating an angular variabli1ity and an elongation index, has been shown to be clearly consistent with visual observations. A single-parameter angularity index has been shown to be very sensitive to small differences in particle roundness and seems to provide a better description of angularity than other approaches such as signature and fractal analyses. The scheme has been applied to three sets of fine quartz particles produced by different grinding procedures. The results indicate that the technique is capable of distinguishing between angular and re1atively rounded particles and can quantify their specific shape features.

Jan 1, 1991

By R. G. Reddy

Chemical and structural changes occurring during the roasting of refractory gold ores were investigated. Effect of temperature on oxidation behavior of ores was analyzed using TGA, DTA and X-ray diffraction methods. The experimental results showed that the carbon in the ore has to be oxidized to a minimum value before any appreciable oxidation of sulfur occurs. Oxidation rates as a function of temperature were calculated. Optimum conditions under which a successful roasting of the refractory gold ores can be obtained are discussed.

Jan 1, 1990

By Jack E. Thompson

Thank you Tom and JM for that nice introduction. The remarks I am about to make rely on a large way on comments made by Barrick's Chief Counsel, Patrick Garver, to an internal meeting of Barrick's senior staff. I plagiarized so much from his notes that I thought that I should provide attribution. I did get his consent to borrow so freely. What I have done is take his general comments and used my conversations with CEO's and other participants in the industry to enhance the message with concrete examples that underscore the points I wish to make. What you are about to hear is my personal view – I am not speaking as a representative of any company. With that introduction, now would be a good time to give you the main theme of my talk: The SEC should change its rule making to a more public cooperative approach. If that were to happen the SEC would avoid some of the harm it has been doing to the companies in this sector and the very shareholders it seeks to protect.

Jan 1, 2003

By John C. Morrisey, Harold M. Ray

With full production from the Casteel Mine in 1987 The Doe Run Company, a wholly owned subsidiary of the Fluor Corporation, encountered a significant increase of copper and iron to the Viburnum Mill. This major change of the lead, zinc, and copper metal ratios in the ore created circuit problems which adversely affected concentrate quality. Recognizing the problem, the company embarked on a metallurgical research program to include laboratory, pilot plant, and plant testing. The program developed an innovative copper prefloat process which both increased copper recovery and significantly improved concentrate quality. The process was tested and first operated at Doe Run's Brushy Creek Mill then installed at the Viburnum Mill in 1992. A brief history of development, plant operating data, and other potential applications for the patented processes will be described in the paper.

Jan 1, 1993

By Robert Jedrzejczak

The Endako Mine is an open-pit molybdenum mine located in the north central region of British Columbia, Canada, about 960 km (600 road miles) north of Vancouver. Production for the latter part of 1992 was expected to averaged 63.5 kt/d (70,000 stpd). Of that amount, 27 kt/d (30,000 stpd) was the mill feed. This production is achieved with five 11.5 to 14.5 m3 (15 to 19 cu yd) electric shovels, six Euclid R190 and two Unit Rig M120 diesel-electric haul trucks, and three 320 mm (12.25 in.) electric rotary drills. There are three ore zones delineated into pit areas: the Endako, Denak East and Denak West. Present mill feed source is the southeast stage of the Endako Pit. Stripping is carried out in the south wall stage also of the Endako Pit. The mine high grade aggregate is reduced in the primary and secondary crushing circuits before processing in conventional RM-BM-flotation circuits. The majority of the molybdenum sulfide (MoS2) is roasted on site to produce technical grade molybdenum oxide (M003). A portion is further refined and treated to yield a 99.9% pure MoS2 product.

Jan 1, 1993

By Annan Cook

Cyprus Metals' Sierrita mine is located in the Pima Mining District, Pima County, Arizona (Fig. 1), which is one of the largest known porphyry copper districts. The ore body is part of a large mineralized system that includes Cyprus' adjoining Esperanza mine. The copper and molybdenum grades being mined at Sierrita make it one of the two lowest grade porphyry copper mines in the world Mineral production from the district was first recorded in 1876. Copper from replacement deposits in carbonate rocks and copper¬-lead-zinc from veins in volcanic rocks were mined from several deposits. However, it was not until 1957 that the district commenced to become a major copper producer with the beginning of production from the Pima mine, which was the first open pit operation. Since that time, seven other open pit mines have come into production. Because of the variable copper prices and high operating costs, not all of the mines are operating today. A map of certain outcrops, plutons, and open pits, as well as older underground mining operations, in the Pima district is shown in Fig. 2.

Jan 1, 1991

By R. L. Grayson, Y. J. Wang

An integrated approach to the management of underground coal mine production and cost is presented. A conceptual model for objectively analyzing an underground mine to obtain lower cost and higher productivity from operations is outlined. The model is designed to provide mine managers with a quantitative, decision-assisting methodology that can be used in formulating timely responses to fluctuations in operations. It consists of a productivity fore- cast component, routine use of current resource consumption factors, a linear programming scheduling component, a manpower loading analysis, and an inventory control component. The model is applied to an underground coal mine.

Jan 1, 1990

By Stanley R. Riggs

Extensive phosphate resources occur within the Miocene Hawthorn and Pungo River Formations which have not been considered in the past since they were poorly known and were not available to conventional mining. These resources include 1) deep phosphates that occur below 75 meters of overburden within major sediment basins throughout the southeastern coastal plain, and 2) offshore phosphates that occur on the continental shelf and within the U.S. Exclusive Economic Zone (EEZ). The future potential of these two vast resources will be realized with development of new mining technologies such as hydraulic slurry mining and integrated with advanced technolgy already being utilized in the offshore petroleum industry.

Jan 1, 1986

By G. J. Jansen

Introduction The usefulness of microscopes in exploration and ore dressing, problems has been documented for the older generation of mining industry personnel in such publications as Schneiderhohn and Ramdohr (1931). A more recent publication that examines the subject is Process Mineralogy, a conference proceedings of The Metallurgical Society (TMS, 1981). However, it is worthwhile to review some of the principles and advantages of microscopic examination of rocks, ores, and mill products. Transmitted light Microscopists can look at materials in transmitted or reflected light. Studying transmitted light is what is usually meant by petrography. In this method, the light passes through the specimen. The upper polarizing filter can be moved in (crossed nicols) or out (open nicols) of the light path. The specimen can be a thin section, a slice of rock mounted on a glass slide and ground to 30 µm (>400 mesh). Or, it can be a sample of rock or ore crushed to about 70 µm (200 mesh). Transmitted light study is particularly suited to gangue minerals, such as quartz, carbonates, and feldspars, and to the study of alteration processes and products. It has some applications to liberation studies. Minerals are identified in transmitted light by observable and measurable optical parameters, such as cleavage and twinning. Figure 1 is a photomicrograph of the mineral microcline, (original

Jan 8, 1985

By Christopher Haycocks, Randolph Reed, Erik C. Westman

The industrial Source Complex (ISC3) model is the accepted standard used to predict emissions of particulate matter less tan 10µm in diameter (PM10) from industrial operations. This model, however, over-predicts PM10 emissions from surface mining operations, making permits harder to obtain. The over-prediction is likely due to the fact that the model applies emissions from mobile (dynamic) sources to stationary (static) areas. Utilizing a Gaussian dispersion equation, a Dynamic Component Program was created to correct the over-prediction of the model and results in a much more realistic modeling of actual conditions from mobile sources.

Jan 1, 2002

By Blair K. Salisbury

Dissolution within Permian evaporites of the Delaware basin has created extreme lateral geologic and physical property inhomogeneity within and above the evaporites. Discriminating a sulfur deposit's geophysical signature from other variances is difficult. This is particularly true of porosity-dependent gravity and electrical methods. However, other techniques that detect alteration of strata above sulfur deposits may be applicable individually or in combination with other types of data. Relationships between sulfur deposits and gravity, magnetic, gamma radiation, spontaneous potential, and soil geochemical measurements are illustrated by data from several Delaware basin geophysical and geochemical surveys.

Jan 1, 1992

By F. F. Aplan

Rather than reiterate what is well known about the flotation of the non-sulfide minerals, emphasis has been placed on those separations which are not so effective. These difficult separations are largely connected with problems of selectivity in the flotation of the base metal oxides, the other slightly soluble minerals, the insoluble oxides and the naturally floatable minerals. The paper discusses possible methods of improving selectivity between similar species and of improving selectivity against the gangue minerals.

Jan 1, 1994

By C. Orf. Chukabarah

Erratic behavior in convergency during iterative numerical-method evaluation of mine ventilation fan characteristic curves is one of the common problems encountered in mine ventilation network analysis. Five different sets of mine fan data points, that had resulted in unsatisfactory fan characteristic curves, were re-analyzed in the present study, using an embedded mine network optimization computer program. Current results revealed that all five fan data sets not only can be satisfactorily fitted as Yang (1992) did with MFIRE subprogram, but can further be optimized with unique solutions as implemented in the present study. It was concluded, inter alia, that the improved MFIRE-based mine fan curve-fitting computer subprogram (SPLINE) produces satisfactorily similar fan curves as SPSS-based curve-fitting algorithms, including when the latter method uses either standardized or unstandardized fan curve data sets.

Jan 1, 1993

By J. Shibata

Separation of rare earth, especially Nd and Sm, was investigated by batch and column methods with a solvent impregnated resin. The solvent impregnated resin was prepared by impregnation of organo- phosphorous extractant whose trade name was PC-88A into a macro porous resin. The adsorption behavior of rare earth with a solvent impregnated resin in a batch method is the same as that with solvent extraction. In a column method to separate Nd and Sm, the effective separation in both adsorption and elution processes can be attained by setting suitable conditions, such as bed height, flow rate and concentration of eluent. Neodymium which is a lighter rare earth is separated from Sm an adsorption step, while Sm in which is a heavier rare earth is recovered in an elution step. From the integration of breakthrough and elution curves, yield of Nd and Sm is calculated in the condition of 100% purity. It was found from the results of life test of the resin that the solvent impregnated resin can be repeatedly utilized at least 20 times.

Jan 1, 1995

Projections of coal reserves in Central Appalachia are essential for long-term planning in the region. Annual production is declining in states such as Virginia. And minable reserves for the Central Appalachian coalfield are challenged by difficult geological, mining and market conditions. To project coal mining longevity in this region, interviews with mining companies were conducted to determine and assess technical and economic factors that affect coal seam minability. This information was ap- plied to seam and coal reserve data developed by state and federal governments. The results were analyzed to determine the effects of various factors on the overall minable coal reserve base.

Jan 1, 1998

By Chen Chuanqing

The Mining design system is a CAE (Computer Aided Engineering) software and was developed as designer-oriented, interactive mode software to perform geological and mining design calculation and graphics. To perform geology and mining design, the deposit model files created by the software "Deposit Modelling System", are transferred to the environment of graphics support software, then a specially developed drafting submodule can be selected to proceed to interactive graphics design. If it is necessary to calculate the grade and quantity of a particular part of the ore-body, another submodule will be called and run. The resulting file is 'transferred back, and the recalculation program takes the data from the file and refers to the deposit model file to create a summary reserve report: The minimum hardware configuration of the system are IBM-AT Basic work station with high resolution graphic monitor and peripherals needed are digitizer, plotter, printer.

Jan 1, 1989