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By C. M. Lundell, F. S. Kendorski, R. D. Prager

The criteria for the design of the shaft/tunnel system excavation at the Rocky Mountain Project was to provide a stable opening during and after construction to receive the concrete lining and to minimize the disturbance of the surrounding rock mass so that the rock mass resists the displacement of the tunnel mining upon internal pressurization. This paper will summarize the geotechnical design of the shaft, elbow, tunnel, bifurcations, and penstocks

Jan 1, 1986

By Suresh K. Bhatt

Appalachian coalfields have been the predominant source of quality coals since the inception of commercial mining in the United States. In a broad sense, Appalachian coalfields can be considered those east of the Mississippi River, representing about 55% of total US coal production. In this special feature on Appalachia in MINING ENGINEERING, emphasis is given to the four coal-producing states of Pennsylvania, West Virginia, Virginia and (eastern) Kentucky. These four states produce more than 90% of the coal from the total Appalachian region, or about 40% of the total US coal production. Historically, Appalachia has been the principal source of coal for domestic industries and for export. There have been numerous fluctuations in the Appalachian coal industry during the past 20 years. Appalachia was affected by cyclical and structural changes in various industries, particularly the US steel industry, and changing world coal markets. It was also the region of more mine worker labor stoppages than other parts of the country. In general, the factors that affected Appalachian coal production over time are identical to those that determined changes in coal production nationally.

Jan 1, 1995

By R. D. Willette

The Hector Mine deposit in the California Mojave Desert has a magnesium-rich clay that formed when lithium and fluorine were introduced into isolated fine lacustrine volcanic sediment during the Pliocene. The intensely deformed deposit has been supplying the highest grade thixotropic clay to the coatings industry for over half a century. A thixotropic clay displays the property of changing from a gel to a sol when shaken, and increases in strength upon standing.

Jan 1, 1995

By Carolyn S. Watkins, Thomas E. Ward, Debby F. Bruhn, Vern Winston, Mary Lou Rowland, Deborah K. Bulmer

The genetic characteristics of members of the genus Acidiphilium are poorly understood. As part of our study of the genetics of these bacteria, a search was made for an endogenous bacteriophage. Such a bacteriophage has been discovered. Several properties of the phage have been investigated. The phage has a lambdoid morphology and is somewhat larger than lambda. A variety of factors which affect phage stability have been investigated. The bacteriophage infects several of the strains that have been tested. Study of this bacteriophage should greatly increase our understanding of genetic mechanisms in Acidiphilium.

Jan 1, 1989

By T. I. Probert, B. W. Burdett, L. B. Hales

Selecting a mineral processing control system from the multitude of offerings can be a formidable task. To assist the plant designer, the material in this chapter includes the advantages and disadvantages of different equipment types, configurations, and control strategies. Selection procedures are detailed, and the importance of each step in the design and selection process is explained.

Jan 1, 1986

By S. G. Malghan, D. Santhiya, S. Subramanian, K. A. Natarajan

The adsorption of poly(vinyl alcohol) (PVA) of molecular weight 25,000 onto alumina was studied as a function of pH. The adsorption isotherms were also determined. The adsorption density increases with increasing pH, while the isotherms are rounded and of the low affinity type. Electrokinetic studies indicate that the electrophoretic mobilities are reduced in magnitude in proportion to the PVA concentration, without any shift in isoelectric-point (iep). This resembles the influence of an indifferent electrolyte. The calculated values of the free energy of adsorption between alumina and PVA are suggestive of hydrogen bonding. FTIR spectro-scopic data provide additional evidence in support of hydrogen bonding.

Jan 1, 2000

By W. P. Stroud, R. S. Dennen

A ground penetrating synthetic pulse radar system has been used by the US Bureau of Mines to probe into a coal pillar to locate hidden structures or anomalies. Direct matrix inversion was used to obtain a velocity image of the interior of the pillar. The reconstructed image showed the existence and location of a relatively low velocity material within the pillar. Core samples were taken from the pillar in a region surrounding the low velocity material. Analysis of the cores showed the presence of a clay vein coinciding with the low velocity material imaged in the tomogram.

Jan 1, 1992

By K. Eric Livo

The Front Range Infrastructure Resources Project (FRIRP) of the U.S. Geological Survey (USGS) is currently using Landsat Thematic Mapper? and air- borne-visible-infrared-imaging-spectrometer (AVIRIS) data along with planned thermal-infrared data and interferometry-synthetic-aperture radar (IFSAR) data to assess the industrial-minerals quality and quantity along the Colorado-Wyoming Front Range Urban Corridor and to characterize surrounding areas. Landsat? satellite data show synoptic views of the corridor, which may readily be used to identify potential regions of permissible terrain, such as river drain-ages, pediment surfaces, upturned lithology, and bed- rock exposures, where various types of deposits may occur. Descriptive models of these deposit types are used to define the physical features that need to be recognized and characterized. In the case of Landsat? data, the measured light is either reflected or partly absorbed by surface materials, depending on the wave- length of the light, which allows coarse mineral classifications to be made.

Jan 1, 1999

By D. Lelinski, X. Nie, J. D. Miller, J. Hupka, K. Bukka

A preliminary characterization of soil components contaminated at a low level (7 nanocuries per gram) with toxic/radioactive metals has been carried out. Most radioactivity and metals content were present in the minus 100 mesh (<150 µm) size fractions. None of the size fractions examined qualified for uncontrolled disposal at dump sites, thus all material would have to be moved to discharge-controlled landfills. The metal content of the sample was below the limits for economical recovery, therefore eventual processing would be dictated by environmental concerns.

Jan 1, 1992

By M. Ghiani, R. Ciccu

After a short review of the basic concepts underlying the application of selective flotation and electrostatic separation to the beneficiation of phosphate ores, the paper deals with the results obtained with these two technologies for a number of run-of-mine ores of different origin and distinct mineropetrographic features. Problems are discussed in the light of the minero-petrographic characteristics of the ores.

Jan 1, 1993

By P. Mousset-Jones, F. Calizaya

Ultrasonic anemometry is a relatively new method of measuring the air velocity in underground excavations and is not widely used. The method has been mainly used for surface applications, such as meteorology and fluid flow measurement. Several instruments were looked at to determine their applicability for continuous underground monitoring systems. The units fall into two main categories: variable distance units and fined distance units. The method relies on the acceleration and deceleration of ultrasonic pulses transmitted through a moving airstream. This study presents some of the results of the testing of variable and fixed distance ultrasonic anemometers in a wind tunnel and a mine drift.

Jan 1, 1995

By A. S. Polubinsky, V. P. Chernyak

A further development of the theory of heat- and mass transfer in the system “strata - mine opening" is necessary for an improvement of the existing technique of heat calculation of mines and other underground constructions. A generalized boundary problem of heat- and mass conduction in strata around an opening as a theoretical ground for that purpose and several particular situations, important from the point of view of an opening and surrounding strata heat state analysis, as well as results of numerical experiments executed for such analysis are presented.

Jan 1, 1997

By Joachim H. Schubert, David G. Hulbert, Ian K. Craig, Roger G. D. Henning

This paper presents a stabilizing controller for flotation plants which uses a quasi-multivariable technique. The controller monitors all the levels in the plant, and by anticipating interactions between various parts of the plant, is able to stabilize the plant far more successfully than the normal plant control. Once stabilizing control has been achieved, optimization of the process becomes easier and more sustainable. An estimate of the improvement in metallurgical performance is made and a singular value analysis was conducted to verify that the multivariable algorithm will theoretically control better than a collection of individual PID loops. Metallurgical results are presented to show that the improvements are attainable in practice. Control by the Mintek algorithm was alternated with normal plant control, to show that the improvements are statistically significant.

Jan 1, 1995

By P. J. Kientzler, Y. C. Lo

The current study is concerned with the analysis and attempt at simulating the product size distributions obtained from a vibrating ultrasonic device. Systematic experiments of comminution were performed with natural sizes as well as monosizes in order to understand the breakage behavior of the device. A precise analysis of the device&apos;s breakage performance in the case of fine grinding of alumina samples will be presented. Initial steps to model the breakage events using a detailed mathematical algorithm will be discussed.

Jan 1, 1992

Simulation models were developed at the Julius kruttschnitt Mineral Research Centre to provide accurate estimates of power consumption for a wide range of equipment. With the models, a range of circuits and operating conditions can be compared by simulation for a particular ore type. Accurate models of classification allow for the interaction between classifier efficiency and target product size (e.g., P80 or percent passing 150 /an) to be considered. This paper considers a range of circuit types and overall energy efficiency in the context of case studies where different circuit types were treating similar ore types.

Jan 1, 1999

By Y. Luo, S. S. Peng

This paper presents some results obtained from research on long-term subsidence over and near chain pillar systems - the area available to long-term subsidence in longwall operations. Although the long-term subsidence for most longwall operations is insignificant, it does exist in some cases. In the cases that showed significant long-term subsidence, it was found that the development process could be expressed by an exponential decaying function. The stability factor of the chain pillar system and the potential for long-term subsidence are the two most important factors that control the magnitude and development characteristics of the long-term subsidence process.

Jan 1, 2000

By Veliko Kertikov

Complicated processes of heat exchange and evaporation, leading to changes in the temperature and humidity of the ventilating air flow, take place during the driving of headings. In the case when virgin rock temperature is high, the increase in air temperature and humidity is significant. This causes a deterioration of climatic conditions in the headings. Procedures for predicting the changes in air temperature and humidity are discussed, together with appropriate calculations and computer programmes. Predicted results for example scenarios are used as a background for the selection of approaches and means to improve the climatic conditions in a dead-end heading using auxiliary ventilation.

Jan 1, 1997

By C. K. Nworu, L. O. Asuquo, C. O. Nebo

Selective flocculation studies of Agbaja iron ore with starch-type and nonionic polyacrylamide-type flocculants has been conducted to determine the effect of flocculant type. The results indicate that corn starch was slightly better than cassava starch in selectivity performance. Cassava starch was in turn better than Superfloc 16, while the poorest results were obtained with commercial starch. Sodium humate shows better dispersive capability, and thus enhanced flocculation results, than sodium silicate. Pulp pH affects the zeta potential, polymer chain configuration and hence selective flocculation. Overall results indicate that recovery and separation of this very fine grained iron oxide by selective flocculation is feasible.

Jan 1, 1995

By E. J. Dorward-King, R. J. Kadeg, S. Pavlou

Risk assessment, risk management, and engineering/economic feasibility analysis are presented as three effective, practical tools for decision making in the remediation of contaminated soils. Risk assessment is applied to evaluate the extent, magnitude and sources of contamination, to identify appropriate contaminants of concern (COCs). Risk management is then applied to identify the acceptable contaminant residual levels for the COCs. Finally, engineering/economic feasibility analysis is used to define the appropriate cost-effective remedial action and associated target contaminant action levels that will achieve the acceptable contaminant residual levels. A real site application of this decision making approach is presented. This site illustrates that through appropriate engineering, acceptable risk-based contaminant residual levels can be achieved with higher action levels.

Jan 1, 1992

By A. M. Tunstall

Blasting is commonly viewed separately from mechanical handling and crushing. This view is misleading because the degree of fragmentation achieved by blasting can have a significant effect on the efficiency of these processes and, hence, on the overall cost of the mining operation. In this paper, aspects of blasting and crushing and their interaction are examined. A case study is also presented that dramatically illustrates the influence of blast fragmentation on subsequent processing and on the financial implications involved.

Jan 1, 1998