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By D. L. Ealy

At the Beckley Mine in southern West Virginia, forecasting unstable roof conditions in advance of mining is accomplished by using a rating system that combines historical information on mine roof failures with known mine geology. Failure frequency rates are derived for each category of roof rock composition, unit thickness, structure, and extraction ratio. In this manner, known geological environments are rated according to instability based on actual experience. Drill hole control and geological interpretation provide the basis for forecasting unstable conditions beyond working faces. The forecasting technique has assisted mine management in reducing fall frequencies by 80% over the past two years compared to the first five years of operation. This reduction in fall frequency was accomplished by modifying the plan of advancing sections to minimize mining exposure to unstable roof conditions.

Jan 1, 1980

By R. V. Ramani, W. Miola

The MSHA prescribed method for the determination of quartz in airborne respirable-dust samples from underground coal mines is the P-7 method, a combination of low-temperature, radio-frequency ashing (LTA) and infrared analysis (IR). There is no prescribed procedure for quartz analysis in bulk samples of coal and host rock. Dispersive infrared (IR), Fourier-transform infrared (FTIR) and X-ray diffraction (XRD) methods are most commonly used for the analysis of quartz in powders. Several aspects of the experimental procedures, such as the preparation of the analysis sample from bulk samples, ashing techniques, scanning procedures, peak measurement location, calibration techniques, sample amounts, size consist and data interpretation, affect the results from each of the methods differently. Significant differences in analytical results obtained from X-ray diffraction (XRD) and infrared spectroscopy (IR) on the same samples are reported. All studies point to the need for reliable quartz analysis methods. In a recent research program, a procedure for preparing bulk-coal and host-rock samples for quantitative quartz analysis was developed. Further, the results from X-ray diffractometry and infrared spectroscopy for quartz content on identical samples were compared. Calibrations with pure and mixed standards were used to assess the influence of particle-size distribution, matrix and calibration on the analytical results. In this paper, several issues concerning the measurement of quartz in the samples of coal, host-rock and airborne respirable dust from mines are outlined and quantified.

Jan 1, 1996

By Zhen-xing Diao, Feng Zhao, Ya-dong Xue

"Two important aspects of excavation performance of TBM are advance rate and cutter replacement/ring consumption, which is closed to the cost and construction duration of the project. To achieve this, a database of TBM parameters and the geological-geotechnical conditions during the excavation of Yinhanjiwei was compiled and analyzed. Relationships between different geological and TBM operational parameters were investigated. Results of analyzes show that there are qualitative correlation between Field Penetration Index (FPI) and rock geological parameters. And strong relationships between FPI and operational parameters are suggested. In this study, the cutter replacement and ring consumption were analyzed using statistical method for preliminary estimation in similar conditions. 1. ITRODUCTION Hard rock TBM is widely used in tunneling project nowadays because of its advantages to conventional drilling and blasting, especially in long tunnels. The biggest advantage is its high advance rate. However, rock conditions of tunnels are complicated. So TBM performance becomes a primary topic in tunneling engineering, which includes of rate of penetration, utilization, daily advancement, cutter consumption and so on. Many prediction models have been developed to estimate the TBM performance in the project planning phase. The most widely accepted and used models around the world are semi theoretical CSM model (Rostami and Ozdemir, 1993; Rostami, 1997) and the empirical NTNU model (Blindheim, 1979, Bruland, 1998).With increasing uses of TBMs in different ground conditions, an increasing number of researchers have developed new models in order to predict the performance of TBM more accurately in similar geological conditions.(Gong and Zhao, 2009; Hassanpour et al.,2009, 2010, 2011, 2014; Delisio et al., 2013; Delisio and Zhao, 2014)"

Jan 1, 2016

By H. H. Murray

Abstract. World reserves of bauxite are abundant. Domestic reserves are limited and as a consequence the United States must rely on foreign suppliers for over 90 percent of its bauxite. Nationalization of many bauxite mining operations, levying of higher taxes, increased production and transportation costs, and attempts to create a uniform market price combined to place the United States in a vulnerable position. Alumina from kaolin, alunite, anorthosite, and oil shale have-been-or are being evaluated. World bauxite reserves are increasing and attempts to establish a uniform price have failed; therefore, it may be many years before domestic non-bauxite sources of alumina can compete with imported foreign bauxite.

Jan 1, 1980

By R. Das Gupta

Variations in the characteristics of bentonite, magnetic taconite concentrate and system water have been examined to show their effects on pelletizing. Chemical methods have been tried to alter the clay or the system water so as to obtain pellets with desired properties. Those methods include ion exchange and the use of supplemental binders (organic and inorganic).

Jan 1, 1978

By Simon W. Houlding

This paper summarizes recent developments in computer modelling and estimation technology. Significant improvements in computational and modelling efficiencies have advanced technical computing to the stage where, for the first time, it can be realistically applied to short-term mine planning and production control. Real-time interactive grade estimation of complex shapes, volumes and grade distributions, based on immediate turn-around of production sample grades, is now possible. An added benefit is the ability to produce complete geostatistical estimates which include confidence limits. These can be incorporated into the decision making and risk assessment processes of production control. Why the need for new technology? What is wrong with the conventional methods which have sufficed for the last thirty years? The response is manyfold. They suffer from inefficient computational processes and conflicts with geostatistical theory. They are responsible for constricting the flow of information between the disciplines involved in the mine production process. Finally, it is illogical to approximate irregular geological and mining volumes with orthogonal sets of rectangular blocks. Geological materials do not occur in block formation; and mining methods which excavate rectangular blocks have yet to be developed. Other computer based technologies have evolved out of the dark ages of rectangular approximations and have successfully dealt with irregular three-dimensional geometries. It is time for computing in the mining industry to follow this example and take full advantage of available technology. To provide the necessary background, consider the basic requirements for successful implementation of technical computing within the mine production process.

Jan 1, 1992

By Robert L. Randall

The mineral industries have a continuing need for market forecasting and analysis for a variety of purposes, among which are organization and control of the sales effort, financial and corporate planning, and evaluation of the anticipated revenue from investment in proposed projects. For anything beyond the simplest extrapolation, some kind of economic reasoning or analysis is called for, which may or may not be incorporated into a formal or quantitative model. The principles described here apply to most of the commercially significant minerals and metals. The examples are drawn largely from the copper market, as it is the one with which I have the most practical experience. Practical forecasting is the process of analysis and synthesis from three categories of knowledge: facts and statistics, theory, and practical knowledge and informed opinion. Although many attempts have been made to build forecasts on only one of these three pillars, none has been successful as an operating procedure because of the lack of balance. There are no facts about the future-only about the present and the past. Facts can illuminate the future, but the future can be described only in terms of probability or more or less likely states of affairs-not as a continuous extension of the past and present. Likewise, theory, although useful as an organizing discipline and for providing a methodology of analysis, is inadequate for the complexities of reality. This is especially so when there is feedback between plans and forecasts to produce a new outcome and when there are significant elements of unpredictable free will, such as presidential jawboning or foreign policy considerations. Such elements are difficult to accommodate in neat theories, although they must certainly be reflected in the forecasts. Pure opinion frequently suffers from both a lack of-disciplined reasoning and the presence of biases or self-interest. While the future is unknown, it tends to cast its shadow before it; hence, forecasting is the art and science of positioning oneself so that the shadow becomes visible to the forecaster.

Jan 1, 1979

By J. Y. Kim, S. L. Chryssoulis

Lead ions that originate from galena during the processing of complex sulfide ores migrate onto the surfaces of sphalerite and iron sulfide minerals. This results in poor selectivity during differential flotation. Generally, in sulfide ore processing, the lead-activated minerals float in the Cu/Pb rougher circuit. The surface lead complicates the zinc flotation circuit by lowering the concentrate grade. The effect of lead in the differential flotation of sphalerite from Cu-Pb-Zu and Pb-Zu ores is discussed. Plant and laboratory-test data are interpreted by determining the surface compositions of individual grains of sphalerite and iron sulfide particles. For the first time, surface compositions were determined by using laser-ionization mass spectrometry (LIMS) and time-of-flight secondary ion mass spectrometry (TOF-SIMS). Cationic and cationic species on the surface were analyzed to elucidate the phenomena. It was proven that these new techniques are very useful in understanding the basic mechanisms of a sulfide mineral-flotation system.

Jan 1, 1997

By Michael A. Werner

"A Yieldable Structure for Use in Areas of High Rock Stress & Deformation." Rock stress of up to 9000 psi have been recorded in the mines of the Coeur d'Alene Mining district. Associated with these large stresses are rock fractures and deformation. In order to maintain openings required for mining, large wood preparation structures are constructed to provide access to the work areas for men and materials. These wood raise preparation structures are costly to construct and maintain. Therefore a steel-foam concrete structure was designed and proposed for testing which would be less costly to construct, require no maintainence and maintain its structural integrity while allowing up to 53 inches of wall rock deformation.

Jan 1, 1984

By Armine F. Banfield

The Purpose of the Paper It is fitting that the first paper of a session on the Financial Aspects of Mining should be on the basic data upon which any financial discussion of a mining project must be based. The history of a mining project starts with exploration in an area considered geologically favorable for mineralization and culminates in the discovery of a body of valuable mineral material commonly known as a mineral deposit. Subsequently more detailed exploration establishes the approximate size, shape, tonnage and average grade of the deposit by surface and/or underground drilling, -surface trenching and/or underground workings. Some preliminary metallurgical testing and other studies, as required, are made at this time. Development work is then carried out to provide representative samples for determining flowsheet and metallurgical balances, preparing the deposit for production and establishing more firmly the grade and mining characteristics of the deposit. A feasibility study is then made of the engineering aspects of the project including the estimation of operating coats, the capital required to place the deposit into production, profit and return on investment. A valuation of the deposit

Jan 1, 1972

By Numan Elmas

Barite deposits located in Dinek and surrounding region have important economic features with their large reserve capacity for Turkey. The objective of this study is to elucidate geological and depositional characteristics in terms of. site investigation and chemical analysis. In order to do this, geological area of about 300 km2 was examined and detailed geological map was constructed. It was observed that Barite mineralization in these deposits was occurred in carbonate and pelitic rocks of Lower Cambrian-Lower Ordovician. Deposits were exposed to advanced diagenesis regional metamorphism and tectonics that rotated and deformed the barites; therefore, barites shows secondary veins, brecciate and fracturing structure. Even though, a few light isotope values of barites may suggest hydrothermal and exhalative sedimentary characteristics or possible mixing with magmatic fluids, generally heavy isotope values indicate that the sulfate ions were supplied from coeval seawater and, many of sedimentary features and petrological, geochemical characters support dominantly sedimentary origin.

Jan 1, 2005

By Y. Topkaya, R. E. Johnson, B. R. Palmer, R. B. Bhappu, J. Brent Hiskey, Gürses Öner

Currently there is considerable interest in applying in situ leaching technology to recover copper from oxide ores. In many instances, the distribution of copper mineralization in these deposits is fracture controlled. Laboratory core-leaching experiments have demonstrated that leaching response is sensitive to the dissolution of copper from and the formation of channels along main fractures. Solution short- circuiting can be a major limitation of this technology. This paper describes the application of macromolecular polymers to achieve flow-profile control during leaching. Pre- and post-leached fractures were characterized by computerized tomography (CT) analysis.

Jan 1, 1993

By Stephen Stone, Kerby Dobbs, G. Richard Whittecar, W. Lee Daniels, Zach Agioutantis, Tess Thompson

A common result of Environmental Impact Assessments associated with mining projects is the construction of new wetlands in areas disturbed by mining operations. Where appropriate, this mitigation may be considered an integral part of the mine reclamation process under the principles of sustainable development in the minerals industry. Wetbud is a new tool for estimating wetland water budgets using available weather data and site-specific topographic, soil and geohydrologic data, coupled with mass balance mathematics. Wetbud is primarily intended as a planning tool for use in the design of created wetlands, but it can also be applied to native wetlands or wetland restoration sites where the required input parameters can be specified. Wetbud can be run in its basic form where wetland topography, soil parameters and groundwater flux are simplified, or in the advanced form, where these parameters are included in a more complex approach via integration of the MODFLOW package, a free 3D program that was developed by the United States Geological Survey. Both versions can also include overbank flow hydrology sources and the advanced form can also model sloping and irregular topography. The program downloads weather data from the nearest applicable station and selects appropriate wet-normal-dry (W-N-D) years following a modest user data clean-up step. Wetbud also has the ability to utilize existing short-term (e.g. 6 to 9 months) groundwater data from an up-gradient well to simulate longer-term groundwater level inputs for the selected W-N-D years. In addition, Wetbud features a “Wizard” version that comes pre-loaded with 14 pre-selected weather data sets for all areas of Virginia that can develop a simple monthly water budget in less than 15 minutes – a feature that could be expanded anywhere geographically with historic weather data.

Jan 1, 2017

By A. K. Bakshi

Mineral suspensions show Newtonian flow properties at lower solid concentration, but change into non-Newtonian regime as the solids content is increased. For Newtonian fluids viscosity is independent of shear rate, but for non-Newtonian fluids it varies with rate of shear. Therefore, measurement of viscosity at a shear rate, different from the process will be futile unless the slurry is Newtonian. This is especially true for hydrocyclone operation, where the rate of shear is different at different points within the hydrocyclone. In this case, it is very important to determine the flow type of the suspension before attempting to establish any correlation between viscosity and process efficiency. A new technique to distinguish such changes in flow type has been developed. This involved a co-axial cylinder type viscometer which measured apparent viscosity at a low shear rate, and a vibrating sphere type viscometer which measured the apparent viscosity at a high shear rate. Special precautions were taken to allow measurements of viscosity of rapidly settling mineral suspensions. Because the vibrating sphere viscometer operated at a much higher shear rate than the rotating viscometer, the two instruments together could determine the shear-rate dependency of the viscosity. Ground silica of 80% passing 65~m size in water was used to prepare slurries at concentrations ranging from 1O-70wt% solids. Viscosity of each slurry sample was measured simultaneously by both the viscometers and the results were compared with each other. With this technique, it was found that all the silica slurry samples were in the Newtonian flow regime.

Jan 1, 1995

By S. J. Czehura

The Butte quartz monzonite is the host rock for early porphyry copper style mineralization and subsequent mesothermal-epithermal, enargite-gold style veining that transects the district. The east-west Anaconda system veins: including the Emma, Anaconda-Original, Syndicate, Badger-State, and Alice-Rainbow veins, each with strike lengths of over 12,000 feet and vertical continuity in excess of 4,500 feet, along with mining widths from 5 to 50 feet, are unique to Butte. The incredible dimensions and tenor of these veins have yet to be surpassed and Butte is still touted as being the “Richest Hill on Earth.” The Anaconda Company was formed in 1895 to develop underground copper reserves in the district and eventually consolidated all operations under one company. Production from underground mining continued through the mid-1970’s. Open pit mining in the Berkeley pit began in 1955 with the extraction of supergene ores, along with the remnants of deeper horsetail zones inaccessible to the underground mines. Operations in the Berkeley pit were suspended in mid-1982 because of the rejection of high arsenic, copper concentrates at major smelting facilities throughout the world. Bulk mining of porphyry style mineralization in the Continental pit began in January 1980 to supplement copper production while stripping “C” pushback in the Berkeley pit. The Anaconda Smelter closed in September 1980. A molybdenum circuit was added to the Butte Concentrator in 1981 and mining continued in the Continental pit to produce copper and molybdenum concentrates. A blend of Berkeley and Continental ores were processed to dilute penalty metals in the final concentrates marketed to toll smelters. All mining operations ceased mid-1983 when Anaconda closed the Continental pit and offered the property for sale. Montana Resources reopened the Continental pit in June 1986 to produce copper and molybdenum concentrates. Operations were suspended mid-2000, because of exorbitantly high power prices, but resumed in November 2003 with rising metal prices. Bulk open pit mining of the early porphyry style mineralization has sustained production over the past twenty years and mining is expected to continue in the Continental pit with favorable prices. Future mining will eventually develop a 500 million-ton geologic resource incorporated in a supergene enrichment blanket situated between the Berkeley pit and the Continental pit. Grades in this enrichment blanket range in the neighborhood of 0.5% copper.

Jan 1, 2006

By O. E. Brown

The measurement principle of the Coulter Counter for particle size analyses is described. The application of the Coulter Counter to cement particle content and size analysis and to the size distribution of clinker from standard grindability tests are described. Methods of calibration, sample preparation and data reduction are presented. The results of the analyses obtained are compared with characteristics associated with performance showing both concordance and non-concordance of test data., Future uses of the Coulter Counter for particle size analysis in research and plant control adaptations are indicated.

Jan 1, 1960

By D. Robert Weir, M. J. H. Ruscoe, R. M. Berezowsky, M. A. Clegg

The metallurgical processing involved in the produc-tion of the new Canadian one dollar coin is reviewed starting with the hydrometallurgical production of pure nickel powder, followed by the powder metallurgy process for the production of nickel strip and coinage blanks, and concluding with the Aureate bronze electroplating and heat treatment procedure. Coinage requirements are then reviewed with regard to economic, public acceptance, and service requirements. Finally the properties of Aureate nickel coinage are presented in the light of the many and varied coinage requirements, and it is concluded that the new Canadian dollar coin exceeds the requirements admirably.

Jan 1, 1990

By J. A. Brierley, C. L. Brierley

The history, current applications and future of biotechnical developments in the metals' extraction industry are reviewed. Bioleaching of copper minerals continues to be the most significant application. Uranium bioleaching was successfully demonstrated at industrial scale. Developments are now being made in biooxidative pretreatment of refractory gold concentrates, ores and low-grade materials. Advancements are forthcoming in water and solid mine waste bioreclamation, including metals' biosorption, wetland treatment of acid mine drainage, and biodegradation of cyanide in spent, heap-leach operations. Better understanding of the types and functions of microorganisms involved in metal interactions could advance genetic engineering applications in bioleaching and bioreclamation.

Jan 1, 1993

A digital computer program has been developed to mathematically simulate the effect of limited changes in feed rate on the grinding circuit of an operating mill. The data on which the program is based was supplied by the staff of the mill in question. Samples taken around the complete grinding circuit were analyzed for solids content and particle size distribution for two feed rates. Matrix models were used to represent the grinding units: rod mill and pebble mills. Parameters for these models were computed using a method developed by Mular(l). Classifier parameters were computed by the Powell search method(2) for the Plitt model (3) . The simulation program, which permits the computing of the size distributions in the circuit resulting from the changes in feed rate between the two measured values, assumes that a linear relationship exists between the corresponding parameter coefficients. The program uses an iteration method to bring the simulated grinding circuit to a steady-state material balance for any specified' feed rate between those measured. The program is, in addition, extremely fast and economic in computing time. The results show that the simulations are not everywhere consistent with practice. For example, higher feed rates on simulation predict finer products. These errors are shown to be attributable to anomalies in data gathering techniques. An improved sampling procedure for grinding-circuit data gathering is suggested for future simulations of this type. It is concluded that the

Jan 1, 1971

By John Jonkman

The cost of equipment maintenance is the largest single expense at many mines and processing plants. It is not unusual for a maintenance and repair budget to be larger than 50% of the punt's total budget. Generally, in the mining industry, 400-60% of the work force in a plant reports to the maintenance department. Studies have shown that many plant maintenance workers are only 33 to 40% productive, working 2.6 to 3.7 hours of every 8-hour day. In recent years, many companies have begun to recognize that- productivity improvements and cost reductions can he achieved by upgrading maintenance methods. This paper discusses ten common causes of low maintenance productivity and how recent advancements in computing technology can be utilized to address these causes for low productivity.

Jan 1, 1986