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By Kotaro Ohga, Gota DEGUCHI, Kiyoshi HGUCHI

The situation of Japanes coal mine is in the severe enviroment, because the policy on coal mining has changed. Every year one or two coal mines will be foced to close. To continue the production of coal, we have to reduce the cost of production. Therefore, the mining by longwall method which is more than 250m was attempted at Taiheiyou Coal Mine to reduce the cost and this mining method have had successful results. To get successful results by this mining method, the controlling and prediction of gas emission from the longwall panel will be most important things. In this paper, the comparison of the predicted gas emission from the mining panel based on the measured gas content by using new device with the observed results is described.

Jan 1, 1993

By C. L. Karr, E. J. Gentry

Researchers at the U. S. Bureau of Mines have developed a control algorithm to efficiently manipulate chaotic systems. The control, based on both fuzzy logic and genetic algorithms, prescribes actions that drive the chaotic system to acceptable regions of state space. The use of fuzzy logic enables a person who has limited experience with a chaotic system to establish a set of rules for manipulating the problem environment, and a set of membership functions that define terms used in the rule-set. Genetic algorithms are search algorithms based on natural genetics, and are used in the control algorithm to select membership functions that provide for a suitable level of control. The Bureau-developed algorithm controls the computer simulation of a ball bouncing on an oscillating table, a system that exhibits chaotic behavior.

Jan 1, 1993

By Yuusaku Tominaga, Sukumar Bandopadhyay

A power-series trend curve of elapsed time was estimated by using time series data of measured concentrations of carbon monoxide in the Taiheiyo coal mine, Hokkaido, Japan. The difference between the moving average concentration data and the estimated data from the trend curve showed linear correlation when plotted on a normal probability paper and a correlation coefficient value of 0.99. It is concluded that the estimate of carbon monoxide concentration using moving average values of concentrations compares very well with the results obtained from the trend curve within the three-sigma (standard deviation) range of the distribution. Thus, it is believed the results can be used to monitor and detect abnormal ventilation conditions in a ventilation network such as the occurrence of spontaneous combustion at an early stage.

Jan 1, 2002

By I. de Jong, G. Van Weert

Silver cyanide adsorbs extremely well on activated carbons. This suggests that the addition of soluble silver salts to trace cyanide containing waste streams should allow efficient cyanide removal with active carbon. Silver losses, however, would make this method expensive and also objectionable, since silver has biocidal effects. When silver impregnated carbon is used, these problems are overcome. Test work has shown that such silver remains on or in the active carbon, that cyanide concentrations can be reduced to the level of detection (< 5 ppb) and that the silver impregnated carbon can be reactivated with equipment similar to that now in use at gold milling operations. Initial results on the type of carbon, the impregnation procedure and the level of silver, and the effect of repeated regeneration are discussed.

Jan 1, 1992

By J. G. Groppo, B. K. Parekh

Removal of moisture from fine (minus 28 mesh) dean coal to 20 percent or lower level is difficult using the conventional vacuum dewatering technique. High pressure filtration technique provides an avenue for obtaining low moisture in fine clean coal. This paper describes a couple of novel approaches for dewatering of fine clean coal using pressure filtration which provides much lower moisture in fine clean coal than that obtained using conventional pressure filter. The approaches involve (a) split stream dewatering and (b) addition of paper pulp to the coal slurry. For Pittsburgh No. 8 coal slurry, split stream dewatering at 400 mesh provided filter cake containing 12.9 percent moisture compared to 24.9 percent obtained on the feed material. The addition of paper pulp to the slurry provided filter cake containing about 17 percent moisture.

Jan 1, 1995

By M. Niinae, Y. Nakahiro, K. Yamaguchi, T. Wakamatsu

The rare earth magnet has a good performance and the production is increasing year by year. Two types of rare earth magnets are presently made as industrial products. One is a Nd-Fe-B intermetallic compound magnet and the other is a Sm-Co alloy magnet. The mixed scraps of Nd-Fe-B intermetallic compound and Sm-Co alloy are sometimes produced in the step of production. Therefore it is desired that a recycling system of mixed rare earth magnet scraps should be established. In the present study, hydrochloric acid leaching of the oxidizing roasted products of Nd-Fe-B intermetallic compound and Sm-Co alloy and solvent extraction of metals such as Nd, Sm, etc. are tested to obtain the fundamental data for the hydrometallurgical treatment of the mixed rare earth magnet scraps.

Jan 1, 1995

By Hassan El-Shall, Abbas A. Zaman, Brij M. Moudgil

The addition of organic and inorganic dispersants to aqueous suspensions of heterogeneous particles (kaolin) was found to significantly affect the solubility of metal ions from kaolin particles and stability of the dispersion. In most of the industrial applications of kaolin, highly concentrated slurries of controlled stability and fluidity are required. The solubility of kaolin particles in terms of aluminum and silicon ions and its effect on the stability of the slurry was investigated. The main objectives of this study were (1) to study the effect of the extracted metals on the properties and performance of the slurry, (2) to understand the reaction mechanism of dissolution of metals from kaolin, and (3) to understand the interaction mechanism of dispersants with kaolin particles. The controlling variables were dispersant dosage, slurry pH, solids loading, and aging.

Jan 1, 2003

By John L. Watson, Suren Mishra

Many of the wastes produced by modern steel plants are pulps or sludges containing significant concentrations of iron and displaying some ferromagnetic characteristics. These waste materials are often suited to treatment by magnetic cycloning to produce a high solids content underflow and a clean water overflow. Alternatively in the classification mode, the magnetic cyclone can produce a high iron underflow product for recycling by discarding fine non-magnetic material to the overflow. Results for the treatment of a variety of steel plant wastes in 5.0cm, 2.5cm and 1.25cm diameter cyclones, operating with and without an applied magnetic field, are presented. It is demonstrated that the magnetic cyclone increases solids recovery to the underflow product, especially at finer particle sizes and for higher solids content feed pulps.

Jan 1, 1992

By M. Polat, S. Chander

Many models have been suggested in the past to obtain a satisfactory fit to flotation data. Of these, first-order kinetics models with a distribution of flotation rate constants are most common. A serious limitation of these models is that type of the distribution must be pre-supposed. Methods to overcome this limitation are discussed and a procedure is suggested for estimating the &apos;actual&apos; distribution of flotation rate constants. It is demonstrated that the classical first-order model fits the data well when applied to coal flotation in narrow size-specific gravity intervals. When applied to material which is fractionated on the basis of size alone, the use of three parameter models, which were modified from their two parameter analogs such as rectangular, sinusoidal, and triangular, gave most reliable results.

Jan 1, 1995

By David M. Spatz

Team, as defined by Katzenbach and Smith (1993), is a small number of people with complementary skills who are committed to a common purpose, performance goals and approach for which they hold themselves mutually accountable. As the mining industry searches for new ore discoveries increasingly under post-mineral cover, the process of mineral exploration has taken us from prospector to geologist to multidisciplined explorer to multi-disciplinary team. Multidisciplinary exploration techniques have improved in terms of sensitivities and penetration and more than ever before each technique requires specialists with appropriate training and skills to process data and interpret results. To produce a quality product, specialists must collaborate openly and honestly in an atmosphere where the collective result takes into account the knowledge and expertise of each individual and the relationships between all pertinent data sets.

Jan 1, 1998

By Lynn B. Hales, Randy A. Ynchausti

Object-oriented technologies have been developed to more closely model the way we think about the world and our natural approach to solving problems. Higher levels of abstraction, generalization and classification are benefits of an object-oriented approach. Object-oriented programming, design, and expert systems are part of this technology which is shaping the future of real-time supervisory control. Goals of real-time supervisory control systems include: minimizing variations in process operations, improving efficiency, maximizing production, and implementing procedures for starting and stopping the process. Incorporating object-oriented technology in design, development and implementation of real-time supervisory control systems provides new opportunities for these tasks. This paper discusses some of the opportunities and challenges of implementing real- time supervisory control using an object-oriented expert system for a rougher flotation circuit

Jan 1, 1993

By Donald S. Skufca

This chapter focuses attention on major factors pertaining to plant design and general arrangement of equipment. Considered are efficiency of operations, coordination of maintenance and repairs, plant testing of reagents and possible future plant expansions. The design and general arrangement of equipment considers accessibility for maintenance and isolation for repairs, minimum personnel for operations and cleanup, safe working conditions with minimum interruptions to operations. The constant introduction of new reagents requires eventual plant testing and the manner of isolating a “line” or part of the facilities to allow comparisons in the testing of new reagents is discussed. As technology improves and process changes occur, additional equipment or plant expansions are inevitable. Space for these eventualities must be considered while the general arrangement drawings are in the development stages.

Jan 1, 1986

By Thomas J. Martin, James W. Martin, Paul F. Martin

The conveyor belt is the basic building block of a broad range of material handling applications in modern mining systems. The mining plans and site conditions dictate basic system requirements but this is only a part of total design evaluation. The total system in the typical mining situation can encompass all the activities from the excavators at the mining face to the processing plant, site loadout facilities and/or a power plant. The number of alternative configurations which must be evaluated including subsystems and components is limited only by analytical time and creativity. The constraints and issues which must be addressed continue to expand, driven by reliability, environmental impact and cost competitiveness. All of the system requirements must be translated into specifications for costing, final design and construction.

Jan 1, 1993

By R. Costa, A. Kozak, B. Fukuhara

Introduction The Jacobina mine is located in the state of Bahia in northeastern Brazil approximately 330 km northwest of the state capital city of Salvador and 9 km from the town of Jacobina. The Jacobina Mine (Figure 1) is owned by Jacobina Mineração e Comércio, a wholly owned subsidiary of Yamana Gold Inc. The gold mineralization of the Jacobina mine is hosted within quartz pebble conglomerate reefs of the Serra do Córrego Formation which together with the Rio do Ouro Formation forms the Serra do Jacobina mountain chain. The Serra do Jacobina mountains have been mined for gold since the late 17th century. Since the 1970’s, the Jacobina mined has been operated by Anglo American, Williams Resources Inc., Desert Sun Mining Inc. and now Yamana Gold Inc.

Jan 1, 2007

By P. R. McOllough

The Colorado Department of Highways awarded a contract to construct the Second Bore of the Eisenhower Tunnel in August, 1975. The contract was completed June 29, 1979, nine days ahead of schedule, with¬out major claims or delays. The tunneling involved complex construction through difficult ground conditions. The contract, plans and specifications were specifically planned to more equitably share the risks involved and to minimize adversary relationships. The Department produced a detailed tunnel design and maintained responsibility for the design. The contract employed some new provisions; e.g., a review board for settlement of claims and disputes; escrow documents (contractor&apos;s bid documents) to determine the contractor&apos;s basis of bid when determining adjustments. The tunnel contract, plans and administrative efforts employed by the owner and contractor were very successful in this project.

Jan 1, 1981

By G. Zandt, H. R. Pratt, W. A. Hustrulid, M. Bouchon, D. E. Stephenson

PREFACE The National Waste Terminal Storage Program was initiated to conduct the research to select a site for the disposal of high level radioactive waste in deep geologic formations. As part of this program, the Savannah River Laboratory at Aiken, South Carolina, is conducting geologic research of generic applicability on the potential subsurface damage to a repository from an earthquake. Part of this study involved the collection of data on subsurface damage due to an earthquake, and another part involved the calculation of displacement fields as a result of an earthquake. Both of these studies were conducted at Terra Tek of Salt Lake City. This report is an abridged and combined version of both studies which was presented at the Rapid Excavation and Tunneling Conference in Atlanta, GA, on June 19, 1979.

Jan 1, 1979

By S. C. Bandis, N. Barton

During drilling of deep boreholes, local mechanical failures of the wellbore walls may occur due to the inability of the incompetent overburden and reservoir rocks to withstand drilling-induced changes of the stress environment. At present, borehole failure mechanisms in three-dimensional stress fields are poorly understood. Our experimental investigations based on 3-D physical models demonstrate the stabilizing effect of the intermediate principal stress. The latter may play a dominant role in maintaining the integrity of the stress relieving failure zone around the borehole. However, this will depend on the stress anisotropy, the angle of hole deviation and on the angle of internal friction. Our tests also indicate that the failure zone can accomodate high extensional strains. Finally, relations between the physical models and closed-form elasto-plastic solutions are discussed.

Jan 1, 1986

By Gary F. Meenan

The industrial practice of froth flotation for upgrading the quality of fine coal is a relatively complex, expensive, and inefficient process when compared to the coarse- and intermediate-size coal cleaning circuits. The differences in cost and process efficiency can be attributed mainly to the lower equipment throughput, the added cost of flotation reagents, and the fact that flotation is typically a manually operated process susceptible to fluctuating feed characteristics that influence the overall operating efficiency. The emphasis in recent years has been on improving the flotation process efficiency and lowering the cost per clean ton. This has been achieved by larger flotation cell designs, implementation of flotation reagent evaluation programs, and improved process instrumentation and control. These developments are reviewed along with other current coal flotation practices.

Jan 1, 1999

By Z. T. Bieniawski, Nicholson G. A.

This paper describes an empirical constitutive model for underground excavations in rock which equates the deformation modulus to the ratio of the principal stress difference to the major principal strain. The model requires failure criteria which define both the stress difference at failure and strain as a function, in part, of rock mass classification ratings (i.e. Bieniawski&apos;s RMR and Barton, Lien and Lunde&apos;s Q). Available failure criterion allows reasonable estimates of the stress difference for intact rock as well as rock mass. However, a suitable failure criterion for estimating strains at failure for rock was not available. Toward this end, this paper describes the development of an empirical criteria for defining strain at failure for intact rock as well as methodology for developing similar criteria for rock mass.

Jan 1, 1986

By P. Somasundaran, C. C. Harris

The power consumption of stirred-media mills was studied using an approach developed from work on stirred reactors. Evaluated were the relationships of factors such as stirring speed and impeller and tank dimensions on the torque required to rotate disc and pin impellers immersed in dense particulate media. Data collected under carious experimental conditions were analyzed. The results were summarized and presented in the form of characteristic plots, general equations and dimensionless group correlations involving power and modified Reynolds numbers. Special attention was directed towards the rheological properties of the media, which was considered a non-Newtonian liquid, and hence the equation of power-law liquids was employed. A procedure for estimating the parameters of effective viscosity and scale-up guidelines (with respect to power consumption) are proposed.

Jan 1, 1996