Search Documents

By Jeong-Heum Kim, Jan M. Mutmansky

The primary purpose of the research summarized in this paper was to experimentally investigate the performance of numerous mine ventilation network iterative solution procedures under controlled conditions to determine which procedures were most favorable in terms of number of iterations and total computational speed. The solution methods investigated included: (1) the Newton-Raphson method, (2) the Hardy Cross method, (3) the linear theory method, and (4) the second-order approximation method. The first three of these methods have been widely used while the fourth was formulated by the authors to investigate its potential for ventilation network computation. In addition to the four solution procedures, three methods for selecting the branches in the meshes and three methods for ordering the meshes for computational purposes were also studied during the investigation. As a result of these various options, a total of 36 combinations of solution methods, mesh selection procedures, and mesh ordering schemes were studied. To investigate the performance characteristics of these combinations, an identical set of 180 randomly chosen ventilation networks was used in sets of 30 networks at six different levels of complexity. Here, the level of complexity is defined as a function of the size (number of branches) and the density (number of nodes compared with the number of branches) of the network. To eliminate variations in the solution times due to differences arising from the fans, a single fan with a fixed characteristic was utilized in all the experiments. This paper will deal only with the results for the four iterative methods used to achieve solutions to the mine ventilation networks. The minimum-resistance spanning tree method for mesh selection and random mesh ordering was used throughout the analysis. The conclusions will be based upon a detailed accounting of the efficiency of each method using the total time to achieve a solution to each problem and averaged over the total problem set. However, the number of iterations and the time to complete each iteration will be studied in order to better understand the solution procedures.

Jan 1, 1991

By I. Shah, L. G. Austin

A method for quantitative investigation of the phenomena involved in fine grinding of materials that follows the changes in the breakage rates of fine particles has been presented. For relatively hard, brittle, non-coating material like quartz, the slowing down effect of breakage rates starts to be significant at relatively coarse sizes, which goes often undetected in closed circuit grinding systems, producing relatively coarse product, say P80=75µm However, for fine grinding systems, as the -10µm fractions begin to build-up, and classification becomes more difficult, the build-up of fine sizes causes a slowing down effect Compounding this problem is the difficulty of obtaining accurate cumulative weight size distributions in the fine size region.

Jan 1, 1983

By Ch. Arvanitidis

This work concentrates on investigating the development of a geotechnical classification method for the Greek soils, which can readily provide a rough but usable estimate of the main strength parameters of the soil. It is expected that such a system will be useful to the structural engineer for either checking the laboratory results or for providing a direct estimate in cases where no tests have been conducted. The method provides strength parameter values by relating classification or physical parameters of various types of soils and/or in situ observations of geological and physiographical nature to the strength parameters, such as, cohesion, angle of internal friction, compressibility, modulus of elasticity, etc, by means of a statistical approach and the extraction of empirical formulae.

Jan 1, 2006

By Bezalel C. Haimson

Long before excavation begins, the in situ stresses in the horizon of planned underground chambers can be measured by employing the hydrofracturing technique in existing exploratory holes. Such measurements produce the stress magnitudes and directions required for the rational design of rock structures. Two recent case histories are cited in which preexcavation stress measurements for the design of underground powerhouses proved very beneficial in the orientation of the chambers and the estimation of the stability and required support. A third stress measurement case is related to the preexcavation design of tunnels that will house doughnut-shaped superconductive magnets for the storage of electric energy. In all cases, expensive later modifications were probably prevented by measuring stresses early in the design stage.

Jan 1, 1976

By F. M. Doyle, Jun Li, Milton E. Wadsworth, E. Peters

The Raman spectroscopic technique was used to study electrochernically oxidized pyrite in-situ. It was found that Raman-active sulfur oxidation products could be detected after a proper potential was applied to the pyrite electrode for a threshold period of time. There existed a minimum potential below which sulfur could not be observed. However, when the applied potential exceeded a certain limit, the intensity of the sulfur spectra decreased. The minimum potential at which sulfur could be observed changed with solution pH. For both acid (pH 2.7) and weak alkaline (pH 9.2) solutions, the minimum potential was 0.8 V/SCE, whereas for neutral (pH 6.5) solutions the value was 0.4 V/SCE. In strong alkaline solutions (pH 12.5) surface sulfur oxidation products could not be detected at any potential.

Jan 1, 1993

By Gary S. Brierley, Ronald E. Romley, Alan L. Howard

The Price Road Drain Tunnel in Tempe, Arizona is part of the drainage system constructed in conjunction with the Outer Loop Highway in metropolitan Phoenix. The Outer Loop Project is a part of a much larger expressway system that includes other large drainage tunnels such as the Papago Freeway Drain Tunnels. Large diameter downhole inspection borings were utilized to obtain subsurface data for the design of these tunnels. Subsurface data obtained from the large diameter borings resulted in the development of empirical parameters that were successfully incorporated into the Geotechnical Design Summary Report and which satisfactorily predicted ground behavior, formed the basis for improved geotechnical design criteria, and facilitated the cost effective assessment of third party risk. The purpose of this paper is to describe the subsurface exploration program performed for this project and to explain the methods used to evaluate underground construction procedures.

Jan 1, 1991

By R. Larry Davis

Over the past decade there has been a continual decrease in domestic oil reserves accompanied by a sharp increase in the demand for energy. Even with increased imports of foreign oil, the energy demand has not been met. This has forced many users to turn to substitute fuels. Of the many substitute fuels available most users are turning to and creating an increased demand for low sulfur coal. Because of the increased demand for low sulfur coal as well as the inherent problems in producing eastern coal, many producers have turned their attention to the large deposits of low sulfur coal in the western United States. Western coal mining is, however, not without its problems such as high moisture content, high ash content, highly variable sulfur content, multiple seams, and/or pitching seams. It is to aid in the solution of these problems that this chapter is directed.

Jan 1, 1979

By D. M. Galbraith

British Columbia's physiography - the mountains, valleys and watercourses - provides the basis for rich and varied plant and animal resources and for complex land uses. Mining alters the physical environment in a manner that may create a disproportionate impact on biological resources and land use systems. The object of environmental legislation is therefore largely the protection of the basic physical environment: land surface, water, and air. The pace of mineral exploration, placer mining, and underground and surface gold mining has recently quickened in British Columbia, testing the ability of both industry and regulatory agencies to respond to legislative requirements. Some parameters of mining activity have critical significance for environmental protection, for example: the area disturbed; the physical and chemical qualities of ore, waste and overburden; and the nature of materials handling. Acid mine drainage is a particular hazard. Provincial legislation that applies to mining includes the Mines Act, the Environment Management Act, the Waste Management Act, and the Water Act. Government of Canada legislation includes the Fisheries Act and the Metal Mining Liquid Effluent Regulations. Every new mine proposal in British Columbia is reviewed in the Mine Development Review Process, which receives its mandate from the Provincial Environment and Land Use Cabinet Committee. The proponent submits reports to the Mine Development Steering Committee in succeeding stages: Prospectus, Stage I (after which approval-in-principle may be granted by ELUC); and if necessary Stage 11. Stage 111 is the

Jan 1, 1987

By Thomas C. Atchison, James J. Olson

INTRODUCTION Technologic progress depends on new and innovative ideas, the practical application of these ideas, and finally as the technology is developed and demonstrated, the engineering improvement or replacement of existing capabilities. In many areas the new ideas, although known, are not immediately put to practical use in all applicable fields. Good technologic forecasting for research and development within the excavation field coupled with adequate technology transfer is necessary to ensure timely application of innovative ideas to remove bottlenecks in the total system. The purposes of this paper are (1) to show the potential ability of technologic forecasting to meet future demands in rapid excavation through the acceleration of excavation rates by research and development in several related technologic fields, (2) to provide a brief review of the initial development of the ARPA (Advanced Research Projects Agency) Rock Mechanics and Rapid Excavation Program, (3) to draw attention to the research projects completed or underway in the FY 1970-1972 ARPA program and explain where information or program results can be obtained, (4) to summarize the progress and accomplishments of applied research contracts in the rock disintegration element of the ARPA program, and (5) to discuss the research directions planned for the remaining years of the program. The Advanced Research Projects Agency (ARPA) is a group within the Defense Department responsible for conducting basic and applied research and development for advanced projects assigned by the Director

Jan 1, 1997

By John E. Litz

Coca Mines Inc. is a medium sized company exploring for and developing precious metal properties in the Western United States. They own interests in a number of properties which contain reserves of gold and silver. The Hog Heaven property presently is under development for a combination of open pit and underground mining, followed by recovery of the silver and gold by cyanidation. Property Location The properties included within the Hog Heaven Project are located in Flathead County, northwestern Montana. The property is readily accessible by road from either Polson or Kalispell, Montana, Figure 1. [ ]

Jan 1, 1984

By J. Kulczycka

Poland in time of transition had been dealing with the remnants of the previous regime ? particularly in the field of environmental protection. The burden left was tremendous and there was a need for fast and effective tools for improving the environment. The idea of environmental protection had been supported by the introduction of a new environmental policy that underlined the importance of sustainable development in industry in the beginning of 1990s. This policy introduced high environmental fees and fines ? a concept not very popular in Europe in that time ? and good only for a country in transition to boost the protection of the environment. While this policy had its role to play, its role is now completed. It is time to move forward, especially when these environmental charges affect the international competitiveness of industries so much, and at the same time have virtually no influence on environmental protection investments any more.

Jan 1, 2005

By Norbert Patzelt, Johann Knecht, Wolfgang Baum

High pressure roll grinding (HPGR) is a mature but still expanding comminution technology. In the metals mining industry, HPGR is slowly gaining acceptance as a cost-efficient, high-throughput alternative for plant optimization. The increasing need to treat ores with progressively lower grades, complex mineralogies, refractory metal occurrence and variable rock types requires an energy-efficient comminution technology that reduces metallurgical problems inherent in conventional crushing and grinding, while stabilizing leach and flotation circuits and increasing metals extraction. This paper will summarize our latest HPGR pilot test results for gold and copper projects in the United States and South America and their confirmation through the first HPGR operation in copper mining. This paper will also stress the use of the high pressure grinding roll as a metallurgical tool. The application of HPGR for the treatment of heap leach SX-EW ores, semi-refractory gold ores, waste rock material and concentrator feeds will be illustrated.

Jan 1, 1998

By C. H. Rawlins

Deep bed media filtration is used as a tertiary treatment step (after hydrocyclones and flotation cells) to remove fine oil droplets and solids from oilfield water before reinjection disposal or to remove particulate material from surface waters used for waterflood injection. Oil and solids injection requirements are typically <5 ppm concentration at <2 micron diameter. The preferred media for produced water filtration is walnut or pecan shell, however the use of this media has evolved by trial & error and the fundamental mechanisms that occur during separation and media cleaning have not been investigated. A project was initiated to fill in this knowledge gap by analyzing the physical, mechanical, chemical, and hydrodynamic properties of six types of granular filtration media (12/20 mesh size): garnet, silica, anthracite, pecan shell, English walnut shell, and black walnut shell. Comparison of bed packing, oil wetting, attrition resistance, particle strength, and fluidization has led to an understanding of the preferred filtration media for separation of fine oil droplets and solids.

Jan 1, 2010

By Zhang Youdi

According to general guidelines, deposits suitable for surface mining can be divided into two basic categories: horizontal or flat-bedded deposits and inclined or dip-buried deposits. A series of mathematical models for surface mine long-term planning (SMLTP) has been developed and can be used for any kind of deposit. The basic theory and methodology of the models are oriented- graph simulation which combines graph and network theory with a systems simulation technique to form a new approach. From the viewpoint of surface mining and long-term plan modeling, the main differences between the two categories of deposits are analyzed, an important algorithm is put forward, and the structure of the models and some results of applications are introduced. Dynamic and comprehensive optimizations have been completed by the SMLTP model series. Combining different OR branches, the new approach has been proved to be a powerful tool to solve the strategic problems of surface mine planning.

Jan 1, 1989

By Pierre Mousset-Jones, Felipe Calizaya

The design of an auxiliary ventilation system for long underground openings (drifts, ramps and shafts), often requires the installation of multiple fans. The fans are installed in series and separated from each other by rigid ducts of fixed or variable length. However, problems relating to excessive leakage often occur, with each project representing a unique problem requiring an efficient solution. In this study, a method to determine the design parameters of an auxiliary ventilation system is presented. The method is based on the principle of partitioning a long ductwork into segments of finite length and solving the resulting networks separately. Specifically, the method is developed to solve two types of problems: constant fan spacing, and constant fan size. In the former, the fan spacing is fixed, and the problem is solved for fan sizes. In the latter, the problem is to solve for fan spacing. An example is used to illustrate the method.

Jan 1, 1993

By Anthony Harding, Rodolfo D. Aradas, Juan M. Fernandez, Darío Tsingas

"The adoption of tunneled combined sewerage interceptors and outfalls leads to design linings which are often subject to internal pressures that are larger than the external pressures, resulting in significant tension loads. The need to meet stringent durability conditions for the normal design life of 100 years often drives client specifications to require a double pass solution with a cast in situ secondary concrete lining. However, improvements in concrete technology and the need to seek efficiency in terms of time and costs, have driven designers to consider single pass segmental linings. The Riachuelo Sanitation project in Buenos Aires is subject to these constraints both upstream and downstream of a sewage treatment plant. This paper describes how the challenges of up to 2 bar pressure differential have been addressed by careful analysis of soil structure interaction to ensure that the full benefit of external ground pressure is realized, resulting in a more optimal design for the constructor both in terms of cost and time. INTRODUCTION The construction of long sewerage interceptors and outfalls is becoming an increasingly common piece of infrastructure for modern urban cities facing a large water front and estuarine conditions, which are under a significant environmental burden imposed by decades of sustained growth. Such works intercept most of the distributed sewage discharges to then divert them to a central treatment point from which it will be finally diffused via an outfall into a water body capable to accept these discharges under acceptable environmental conditions. Depending on the magnitude of the sewage load to be handled, the configuration of the urban environment and the conditions of the receiving water body, both in terms of oceanography forces and seabed conditions, these schemes will vary in length, conveyance capacity and design and construction requirements. When conditions permit, the current trend is the execution of long outfalls using flexible solutions (such as the use of HDPE pipes) which usually require some form of concrete ballasted weights to resist off shore dynamic forces when directly laid over the sea bed. However, this concept faces limitations when the conveyance requirements indicate the need for large diameters (typically above 3000 m) and also when the outfall needs to avoid deep features off shore such as navigation channels. When this occurs, tunneling, particularly segmentally lined tunnel constructed by TBM emerges as the most feasible approach for large diameter, long deep outfalls. The operating conditions often result in internal pressures that are larger than the external pressures, resulting in significant tension loads in the lining. The need to meet stringent durability conditions for the normal design life of 100 years often drives client specifications to require a double pass solution with a cast in situ secondary concrete lining."

Jan 1, 2016

By C. McDonald, S. Slottee

Deep "paste" thickeners have been used in the alumina industry for several decades to improve chemical recovery and allow “stacking” of the red mud for disposal. These paste systems have eliminated many traditional tailings ponds in addition to providing better tails washing and better water recovery. This technology is not widely used or understood in other mineral processing applications. However, there is growing worldwide recognition of the advantages of concentrating mill tailings to a “paste”, i.e. a solid suspension that does not settle or segregate. This technology offers several alternatives to the traditional tailings pond such as “stacking” or mine backfill. More water recovery is possible than with high rate thickeners. Process benefits come in the form of better chemical and metals recovery through better washing in counter current decantation (CCD) applications. Obtaining a true paste (non-segregating suspension which exhibits a yield stress) and understanding the handling characteristics for applications outside alumina, are recent developments. Achieving all of the benefits available from a paste system requires careful design that takes into account the specific requirements of the disposal application along with the peculiar difficulties in producing and handling paste. In fact, design of a paste system is markedly different from a conventional system. Project design usually requires the cooperation of experts in several interrelated specialties including geotechnical, thickener design, pumping and discharge design and controls. A successful project must coordinate all activities to ensure that the overall objectives for the project are achieved. This paper describes the properties of paste, reviews the applications, and discusses the design of a complete paste deposition system.

Jan 1, 2003

By D. G. Chedgy

This article presents a novel design, called the Climax High Capacity Processor (HCP), for pre-combustion cleaning of coal. This design is particularly suitable for the plant capacities of 400 -660 TPH. The HCP is different from the conventional designs with an equivalent throughput in three major aspects: 1) the use of one large capacity HM cyclone to separate coarse and intermediate raw coal in a single circuit; 2) the elimination of the conventional secondary magnetics recovery system by use of the high efficiency Climax magnetic separators; 3) the use of "single line" piping with a minimum requirement of ancillary devices. In comparison with conventional designs with similar capacity, the HCP plant costs much less in capital investment, operation and maintenance.

Jan 1, 1997

By R. A. Jankowski

Although the number of operating longwall mining systems has remained relatively constant, longwall production levels during the last five years have increased significantly. In the United States, longwall mining now accounts for approximately 50% of all underground coal production. While longwalls are highly productive and offer other advantages, operations employing this method of mining continue to experience dust-compliance problems. This increased longwall productivity has meant that far more dust is being produced. An improved understanding of the longwall face-ventilation system and the advancement of face-ventilation technologies are necessary to ensure all face personnel are allowed to work in an environment that is free of excessive levels of airborne respirable coal mine dust. The Dust and Toxic Substances Control Branch, National Institute for Occupational Safety and Health, Pittsburgh Research Laboratory, examined several basic principles of the long wall face-ventilation system and has evaluated the effectiveness of numerous improved face-ventilation techniques for longwall mining systems. These include identifying improved techniques for measuring face-ventilation parameters on longwall mining sections and investigating the fundamental relationship between face airflow and the entrainment and dilution of respirable coal mine dust. Studies have been completed to determine the impact on face dust levels of using belt entry air to ventilate the longwall. Novel methods have been identified to increase the face air¬flow and to manage face airflow to effectively minimize dust exposure to face workers. Unique systems of auxiliary face ventilation have been developed and evaluated at full-scale, simulated longwall test facilities. The theoretical and applied aspects of each of these principles and technologies are discussed. Application of these results throughout the longwall mining industry, as documented from surveys conducted in the early 1980s and 1990s, have reduced the health hazard associated with excessive exposure to respirable coal mine dust.

Jan 1, 2000

By Ted H. Eyde

Nearly 17 years ago a major producer of synthetic zeolites started an extensive exploration program for natural zeolite deposits which resulted in the discovery of over 170 occurrences in the western United States. A few years later several of the other producers and consumers of synthetic zeolites also started similar exploration programs. Since then, small quantities of natural zeolite minerals have been produced from at least 12 deposits in the United States. Of these the Bowie deposit, about 13 miles north of Bowie, Arizona, is the most important,having produced over 5,000 tons of vitric tuff zeolitically altered to the mineral chabazite and minor amounts of the minerals erionite and clinoptilolite. Mining Districts and Mineral Deposits of Arizona compiled by Charles A. Mardirosian, Consulting Geologist, estimates the value of the total production from the Bowie deposit at a very conservative $2,000,000. Unfortunately, none of the companies responsible for the discovery and the initial production of natural zeolites made any effort to develop the high volume, low cost applications of this unique mineral raw material. Instead, they developed only the high unit value uses to supplement their existing synthetic molecular sieve product lines. With the producers of synthetic zeolites thinking in pounds and not in tons, further development of natural zeolite deposits stagnated for over a decade.

Jan 1, 1974