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By J. Killian, S. Cox

Many questions exist within the geotechnical industry as to the applicability of Strength Reduction Factor (SRF) values to the design acceptance criteria (DAC) of mining operations. There are many factors that contribute to changes in the SRF estimate, some of which are numerical (e.g. dilation angle) and some of which are geometric (e.g. model grid size)[1]. Numerous studies have confirmed equivalent values of SRF and FOS are found for soil slopes of limited height as presented in, [2] and [3]. However, significant deviation of the SRF value was observed for highly cohesive materials (rock slopes) of heights typically encountered in mining, [4]. This paper builds on the work presented in [4], providing a more rigorous examination of the modeling parameters that control the SRF estimate. The failure mechanism assumed for this study was a simple circular shear surface in a uniform material. Both LEM and numerical methods are suited well for analysis of this failure mechanism. A parametric study was completed to evaluate and test the relationships of key numerical variables that affect the estimated value of the SRF using Itasca’s Fast Lagrangian Analysis of Continua (FLACTM) software. The effect of groundwater has been tested and may be significant but is not presented as part of this body of work for brevity and simplicity of presentation.

Mar 2, 2022

By Libby R. Ricafort, Nonato S. Retardo, Jose B. Anievas

This paper shows the metallurgical test results that led to the design of the heap leach facilities of Philex Mining Corporation. The design incorporates a water management model as process solution circulation is excessive with high rainfall intensity in the area. This poses problems in the operations requiring stringent controls than would be necessary in a less severe environment. The corporate perspective embraces on environmentally-sound mineral development. A budget is always provided to environmental management making certain that no industrial development is moved forward at the expense of the environment.

Jan 1, 1996

If a fire occurs outby an underground coal mine section, the immediate safe evacuation of miners from the working section should always be the first action during the rescue operation. Unfortunately, in many cases, the escape-ways (escape routes) dedicated for miners' evacuation are contaminated with fire byproducts from adjacent entries. The purpose of this paper is to present the ventilation control process that will maintain the escape-way free from contaminants and available for travel. Several scenarios in a different section on ventilation system arrangements are analyzed, discussed and presented. To perform these studies, the author used a mine-fire simulator, which provides a dynamic (in real time) representation of the fire's progress and also gives a display, a color-graphic visualization, of the spread of combustion products throughout the ventilation system. Presented and discussed in this paper, also, are ways in which the mine-fire simulator can be used as a training and teaching tool for miners and, particularly, for ventilation and safety personnel.

Jan 1, 1993

By T. Tamagawa

A gaseous chlorination process for hydrometallurgical treatment of a chalcopyrite concentrate was investigated. The overall process is visualized to consist of low temperature chlorination-selective oxidation, followed by aqueous chloride leaching and SX-EW for producing electrolytic copper, elemental sulfur and ferric oxide. In this article, the chlorination phase of the processes is described. Initially, the chlorination behavior of chalcopyrite-concentrate micro-pellets was investigated using a small batch-type fluidized bed reactor. The optimum conditions thereby established was used in continuous chlorination tests. The chlorinated products thus prepared were used in the selective oxidation phase of the investigation.

Jan 1, 1999

By N. W. Johnson

Two analysis tools which have been applied to problems in industrial Flotation processses are the application of kinetics and detailed mineralogical or liberation data, both on a size-by-size basis. The paper describes practical examples of the application of kinetics to examination of the entrainment recovery mechanism, the retardation of valuable minerals at the commencement of flotation sections and the resolution of problems related to valuable species with reduced rate constants at the end of sections. Examples of the usefulness of size-by-size liberation data for monthly composite samples of products from a concentrator are also described.

Jan 1, 1985

By Hayward B. Oblad

The effects of eight independent variables on froth flotation product yield, ash content, and coal recovery were studied using laboratory batch flotation of 0.6 am x 0 coal. The eight flotation variables investigated were air feed rate, pre-dispersion of collector oil, impeller speed, product collection time, initial solids concentration, collector conditioning time, frother (methyl isobutyl carbinol) concentration, and collector (No. 2 fuel oil) dosage. The two-level Plackett-Burman screening design and the three-level Box-Behnken design were used. Within the ranges studied, air feed rate had no effect on product yield. Pre-dispersion of collector oil, impeller speed, product collection time, initial solids concentration, and collector conditioning time showed only minor effects on the product yield and quality. Frother concentration (mg/L) in the process water and collector oil dosage (g/kg) were shown to be the dominant independent variables in coal froth flotation. Flotation experiments that vary initial solids concentration at constant frother dosage (g/kg) confound the effects of frother concentration (mg/L) and solids concentration. The dominating effects of frother concentration and oil dosage on coal recovery and froth product ash content are illustrated with three-dimensional plots. The relationship between froth product ash and coal recovery is also clearly illustrated by the flotation data.

Jan 1, 1985

By Robert C. Cifelli

INTRODUCTION Background and Objectives Underground coal mining is a vital component of West Virginia's economy. However adverse environmental effects including ground subsidence and aquifer dewatering are often associated with such mining activities. Many families in northern West Virginia still rely on private water wells and springs for domestic water needs. In such areas where underground coal extraction and land subsidence have occurred, a disruption of the ground water flow system commonly exists with subsequent drainage of water to lower levels that may extent as deep as the mine workings; this causes loss of water supplies to landowners and represents a nuisance to mining companies 2 This report represents a summary of an M. S. thesis project in geology at West Virginia University by the senior author (3). The intent for this study was to document the effects of underground coal removal on ground water levels at selected mine sites in northern West Virginia, as observed from water wells, springs, and streams. This research should be useful to coal companies and regulatory agencies and aid in recommendations of future water well locations and specifications in areas of existing or proposed underground coal mines.

Jan 1, 1986

By S. S. Peng

In this paper, the precise definitions for a number of commonly used subsidence parameters are given. The subsidence parameters have been determined using an integrated approach for 110 subsidence cases collected in the major US coal fields. Attempts have been made to establish empirical formulae for the parameters. The results of this study indicate that some traditionally-held concepts should be changed.

Jan 1, 1995

By R. D. Grove, M. F. Elliott, R. L. Weigel

The control of Florida phosphate flotation plants is largely based on the visual observations of experienced operators, both in recognizing good and bad froth conditions and in making judgments about the composition of feed, concentrate and tailing streams. Chemical analyses lag the process by at least two hours and therefore only assist in recalibrating the operators' vision when major deviations occur. An image analysis system has been developed by IMC Agrico Company (IMCA) to improve upon the accuracy and precision of the composition estimation process. It still relies upon the operator taking a representative sample, but provides a measurement in about 15 minutes after that sample is obtained. This paper describes the system and its use and presents comparative results for various process streams.

Jan 1, 1993

By Hans Smit

The face of mining as we know it is set to change in the very near future as mining companies all over the globe realize the implications of accessing the vast mineral wealth contained on, and under, our ocean floors. With some land based mineral deposits being fully exploited across the world, deep sea mining is set to revolutionize global approaches to the search for precious metals and other sought after minerals. [ ] Previously, the financial implications of deep sea mining outweighed the benefits of access to the mineral rich deposits identified all around the world. The process of marine diamond mining off the west coast of southern Africa started in the late 1950?s by a Texan, Sammy Collins, and subsequently continued by De Beers to the present day, has proven to be an excellent proving ground for the development of technology and mining systems that ensure a sustainable and financially viable business. [ ]

Jan 1, 2008

By I. H. Gundiler

Although cyanidation has been universally applied in the processing of gold and silver ores, the search for less toxic alternatives continues. Difficulties encountered in processing ores containing oxidized copper minerals and the inherently slow kinetics of cyanidation have generated a renewed interest in thiosulfate leaching. This process, as well as the catalytic effects of copper ion, were well recognized and widely applied towards the end of the past century. In this study, the effects of copper, ammonia, and thiosulfate concentrations on gold dissolution were investigated using the rotating disk technique. Extraction of gold and silver from an oxidized copper-bearing ore was also studied utilizing a statistical experimental design, and these results were displayed in the form of contour plots.

Jan 1, 1993

By D. S. Yantek, L. A. Alcorn, M. J. Lowe, H. E. Camargo

U.S. National Institute for Occupational Safety and Health (NIOSH) studies show that 43.5% of surveyed coal preparation plant workers had noise exposures exceeding the U.S. Mine Safety and Health Administration permissible exposure level of 90 dB(A). Sound levels around vibrating screens in these plants often exceed 90 dB(A). NIOSH is currently developing noise controls for horizontal vibrating screens. To characterize noise sources, NIOSH researchers performed sound pressure level (SPL) measurements on a vibrating screen at their Office of Mine Safety and Health Research laboratory in Pittsburgh. The results show that the entire screen contributes to noise below 1 kHz, and the vibration mechanism housings are most significant above 1 kHz. Constrained layer damping (CLD) treatments and an enclosure were used to reduce mechanism housing noise in this range from 1-10 kHz. These were evaluated using sound power level measurements according to ISO 3744. The CLD treatments reduced the A-weighted sound power level by 3.1 dB in the 1 to 10 kHz one-third-octave bands. A panel-on-frame vibration mechanism enclosure using various types of panels further reduced the A-weighted sound power level from the CLD configuration in the 1 to 10 kHz one-third-octave bands by 3.7, 4.0, and 3.9 dB for aluminum, steel, and Dynalam™ panels, respectively. The combination yielded a 7 dB reduction from baseline in A-weighted sound power for the same frequency range.

Jan 1, 2011

By K. W. Vincent

This paper, deals with the beneficiation of a low grade Western phosphate to ore. More specifically it summarizes the results of a study made to optimize a scrubbing step in the process, and to provide firmer data for use in plant design. The deposit is situated about 30 miles northeast of Pocatello, Idaho, in the Fort Hall Indian Reservation. It is a bedded deposit and throughout most o the orebody includes three contiguous layers of phosphatic material which differ in P205 content. The J. R. Simplot Company, as operator for a Simplot-FMC joint venture, mines the ore selectively by open pit methods The lower bed containing a nominal 30% P205 is shipped to the Simplot Company fertilizer complex near Pocatello; the middle layer averaging about 24% P205 supplies the FMC elemental phosphorus plant also near Pocatello, The top layer averaging around 16% P205 and designated as mill grade shale is stockpiled for future beneficiation. This paper is concerned with some aspects of the processing of this low grade shale.

Jan 1, 1965

By N. Nemeth

The filter is an apparatus designed to hold the filter medium. At such a medium takes place the entire liquid-solid or gas-solid separation process. Hence, the medium is really the essence of filtration. Yet, the medium, an originally clean porous substance with trapped solids in it, is perhaps the most neglected part of filtration research. Basically three problems prevail at the medium: 1) Penetration of solids and their blinding of the medium and the influence of such blinding on the resistance to flow. ii) The behavior of the medium in long term repetitive filtration. iii) The filter effect phenomenon whereby the flow rate on filtering an apparently clear liquid through a medium decreases with time. This study undertakes to investigate these fundamental processes.

Jan 1, 1968

By Paul S. Parobeck, Robert A. Haney, Andrew J. Gero, Thomas F. Tomb

As a result of recommendations made in the 1988 Report of the Mine Safety and Health Administration Advisory Committee on Standards and Regulations for Diesel-Powered Equipment in Underground Coal Mines, the Mine Safety and Health Administration (MSHA) initiated a program to develop and test a diesel particulate sampling device. The sampling device employed the principles of inertial impaction to separate respirable dust into two fractions; one fraction containing particulate material having an aerodynamic equivalent diameter equal to, or greater than, 1.0 micrometer, and the other fraction containing particulate material having an aerodynamic equivalent diameter less than 1.0 micrometer. The design criteria were based on data which showed that virtually all of the diesel particulate material and very little of the mine generated dust was less than 1.0 micrometer in size. The instrument was tested in underground dieselized coal mines and in the laboratory. Comparative measurements were obtained with the MSHA designed impactor sampler, a University of Minnesota (UM) designed impactor sampler and MSHA's standard respirable coal mine dust sampler. Simultaneous measurements were also obtained with five of the MSHA and five of the UM designed impactor samplers to investigate between sampler precision. The paper discusses the design differences between the MSHA and UM impactor samplers, the precision of replicate measurement obtained with both instruments and compares measurements obtained with the respective samplers of the sub- and supermicron fractions of the respirable material.

Jan 1, 1991

By S. R. Stine

The Cyprus Thompson Creek Mine is located at 2,286m (7500 feet) elevation in the Central Idaho mountains, 61.16 kilometers (38 miles) southwest of Challis, Idaho off State Highway 75. The Thompson Creek molybdenum deposit lies near the eastern border of the late Cretaceous Idaho Batholith within a complexly deformed sequence of Paleozoic sedimentary rocks. Molybdenum mineralization is contained in a composite biotite granodiorite-quartz monzonite stock considered to be genetically related to the Idaho Batholith intrusive event. The ore is being mined by open pit methods and delivered to the concentrator stockpile with an overland conveyor belt system. The concentrator is designed as a 22,680 metric tons (25,000 ton) per day plant at an average head grade of 0.1% Molybdenum.

Jan 1, 1986

By M. R. Peterson

The U.S. Bureau of Mines has investigated new methods for increasing the selectivity in flotation by creating and regulating reagent concentration gradients within flotation columns at steady-state operation. Gradients were generated and traced in a water-only system with the use of fluorescent dyes, and the effects of various operating parameters on these gradients were investigated. From this investigation, it was found that both gradual and steep gradients could be generated in the froth cleaning zone, and that these gradients could be changed through the manipulation of both physical and chemical operating parameters. The application of reagent-gradient control to mineral systems could improve both flotation grade and recovery in commercial flotation operations without the use of additional flotation circuitry.

Jan 1, 1992

By M. Dondi, M. Surracco, G. Alfano, P. Saba

Recent investigations on fine grinding with jet mill miprototypes of original design, constructed at the DIMM and Centro Studi of the National Research Council at Cagliari University, have led to the realization of a third generation micronizer characterized by large capacity and high efficiency. The new model and its distinctive features are described here and the results are presented of grinding tests on typical, high grade Sardinian minerals used for quality products. The operating principles of the jet mill are described in relation to the mechanico-elastic properties of the minerals treated. In particular the efficacy of the comminution process is demonstrated in terms of both solid treated and of impact, attrition and shearing forces generated in the micronizer. Particle size distribution of the finished products are reported, that satisfy the most stringent market specifications for the different minerals, as well as energy consumptions. The alternative operating options for solving particular grinding problems and minimizing energy consumption are discussed. Lastly, the main developments of the jet mill for a possible application at industrial scale are suggested.

Jan 1, 1995

By J. D. Crone

Crone Geophysics Limited in co-operation with Newmont Exploration Limited has developed a ground Pulse electromagnetic method. This is the first unit in a planned integrated system of surface and borehole Pulse EM equipment. Newmont had previously developed an operational Pulse EM unit for use in areas of very high surface conductivity. The Newmont equipment was large, heavy apparatus that required motorized transport. It operated in the equivalent frequency spectrum of 10Hz to 2.5Hz. The basic aim of Crone Geophysics was to design a Pulse EM system more portable than Newmont's. We wanted to operate in all types of field conditions including heavily wooded and mountainous terrain areas. We also wanted to record the higher frequency information that is contained in the Pulse EM waveform. There are three reasons why we thought this high frequency information was important in survey applications: (1) Field tests conducted over massive sulphide bodies in the Arizona desert showed that the desert weathering process tended to break down the electrical contact between sulphide crystals. The net effect is to reduce the conductivity of a massive sulphide body, particularly narrow bodies or highly fractured sulphide zones. In order to detect such occurances the higher frequency information is essential. (2) We wanted to be able to detect occurances with sulphide content as low as 5% sulphides that are usually poor to moderate conductors. (3) We also wanted to be able to determine the presence and extent of surficial conductive formations and clay deposits since many airborne EM anomalies are caused by such bodies. If we have the capability of detecting and recognizing these formations we would be able to explain the airborne anomaly.

Jan 1, 1976

By Alfred G. Hoyl

The author, in exploring a virgin area vertically in two known ore shoots requiring decline shaft sinking, drifting, crosscutting and diamond drilling, chose to use electric, electric hydraulic, and diesel rubber-tired equipment. A rebuilt hoist, and electric hydraulic shaft shovel (mucker), hydraulic sinking drills, single boom electric hydraulic jumbo, electric hydraulic LHD, and electric hydraulic diamond drill were used successfully. Slides of the equipment and its use are shown. The advantages and disadvantages of the equipment are discussed, together with costs and production.

Jan 1, 1984