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By T. C. Rao, D. D. Patil

The fishhook effect, wherein the recovery of fine particles in the underflow increases with decreasing particle size, has been observed in hydrocyclone classification. A systematic study was carried out to determine the factors affecting the recovery of very fine particles to the underflow. Attempts were made to identify factors, i.e., design and operating variables, that affect the size at which this phenomenon occurs. Experimental results show that the sizes at which the fishhook effect occurs is mainly a function of feed size distribution and solids concentration and is less dependent on the design variables.

Jan 1, 2002

By T. R. C. Aston

Extensive undersea coal reserves, identified in the offshore portion of the Sydney coalfield, Nova Scotia, have resulted in the implementation of a multi-year research program to develop site specific guidelines for the undersea longwall mining operations. At present, uncertainty exists regarding the applicability of the current undersea mining guidelines. Preliminary studies have revealed four potential schemes for monitoring seafloor longwall subsidence profiles: seasurface, subsea, geophysics, and direct monitoring. However, further work has indicated that the use of marine geophysical techniques may be the most effective method of identifying and evaluating seafloor subsidence profiles by comparing pre- and post-mining seafloor topographies.

Jan 1, 1990

By Isiah M. Warner, Philip Oldham, John Kennedy, Bennett D. Lass

A new method for determination of residual flotation oils on beneficiated kaolin clays has been developed The method, which yields qualitative information, is based on fluorescence measurements employing a spatially resolved, polychromatic illumination source for excitation, and a two-dimensional detection scheme using a silicon-intensified, video imaging device The method was used to identify residual oils on a beneficiated, Washington County, Georgia, crude clay The results were compared to a similar qualitative analysis performed via capillary column gas chromatography using a flame ionization detector The video fluorometry was the preferred method of analysis

Jan 1, 1983

By M. W. Chanda

This paper presents the development of a rock-creep measuring apparatus using air as the initial pressure source. Servo-controlled machines can and have been used for time-dependent property tests. However, the long-term nature of some tests makes essential the complete independence of stress-maintaining equipment from main power sources or continuously running hydraulic pumps. The main objective of this paper is the development of a creep testing machine that is free from interference arising through power supply interruptions or mechanical maintenance normally associated with many compression testing machines. To achieve this, a compressed-air power source was used to drive a compression ram. A few trial results obtained and analyzed using the transient creep law are in reasonable agreement with the general creep law.

Jan 1, 1993

By V. Dezelic, D. B. Apel

This paper describes the results of laboratory and field experiments conducted to determine the applicability of Ground Penetrating Radar (GPR) for the assessment of the strata thickness and for the identification of separation between bedding planes in stratified rocks. The knowledge about the extent of such separation in the roof layers and information about roof lithology can be used to determine the roof support requirements for underground mines where stratified rocks are present. The laboratory and field experiments were conducted at the Rock Mechanics Laboratory and the Experimental Mine at the University of Missouri-Rolla. The 1.5 GHz high resolution, shallow depth GPR antenna was used for all of the experiments.

Jan 1, 2004

By M. Galetakis, C. Roumpos

A sustainable coal industry needs to achieve a number objectives concerning mainly with superior utilisation of deposits and improved environmental performance. Modern quality control systems, which are greatly based on the on-line analysers, play an important role in achieving sustainability targets. This paper discusses the testing and application of on-line ash analysers installed in the Ptolemais and Megalopolis lignite mines in Greece and examines the possibility of using this type of analyser to control blending and homogenisation operations. The effect of the accuracy of on-line analyser to control process, when used for the characterization of low rank coals with complex and variable composition, such as greek lignites, is examined.

Jan 1, 2005

By P. C. O. Chukabarah

Atkinson's resistance square law is the cornerstone equation for traditional expression of energy losses in mine ventilation engineering. But the nomenclature for the various forms of energy losses are often confused for one another, misapplied or misinterpreted. These forms of energy were re-examined from thermodynamic and fluid-dynamic perspectives. Resultant expressions showed that both incompressible and compressible flow regimes in underground mines can easily be accommodated. Given the well-known three major energy forms, which are equivalent to one another but numerically unequal, corresponding equations to Atkinson's (pressure loss) for headloss and workloss were derived. The thermodynamic weight relational resistance ([w] s2/m5) associated with energy per unit weight (headloss) was dimensionalized for the first time. Also, normalized Atkinson-like equations for headlosses and worklosses were derived to ease direct computations in mine ventilation practice.

Jan 1, 1995

By H. L. Owens, J. W. Fredland, K. K. Wu

The Mine Safety and Health Administration (MSHA) is responsible for reviewing and approving the engineering plans for impoundments, of significant size or hazard potential, that are constructed on coal-mine property. Over the years, technical review criteria have been updated as the state-of-the-practice for dam safety has evolved. The evaluation of stability under earthquake loading, for example, has gotten much more sophisticated for impoundments built using upstream construction. Recent incidents where slurry has broken into mine workings have caused MSHA, mine operators, and design engineers to re-examine this safety issue. This paper gives an overview of MSHA’s impoundment plan review process.

Jan 1, 2003

By John Turner, David Carey

The Robbins Mobile Miner demonstrates the successful combination of hard rock excavation technology and the latest electronic control technology. The mobile miner, a partial face hard rock tunneling machine, features a fully integrated control system relying on a Programmable Logic Controller (PLC). This PLC controls all functions: tramming, steering, boom swing, cutting depth, conveyor operation, air scrubbers, hopper loading and unloading, etc. The machine is fully instrumented allowing the PLC to monitor the results of all commands on a continuous basis, to record data, to evaluate developing problems, or to shut the machine down if necessary. The paper describes the development of the Robbins - Pasminco automated mobile miner and early testing at Pasminco Mining's Broken Hill Southern Operations, New South Wales, Australia.

Jan 1, 1993

By R. H. T. Garnett

Offshore mining of placer diamond deposits along the coast of South Africa and Namibia has become a multi-scale activity. It is a successful offshoot of a land-based mining industry that has operated along the coastline for more than 80 years. Onshore diamond deposits have been worked by several methods from the foreshore to some kilometers inland (Hodgen). These deposits are the foundation of an ongoing industry along the coastline. The offshore diamond industry began in the late 1950s and has now come of age. Diamonds are produced along 800 km (500 miles) of coastline in water 200 m (660 ft) deep. About half of the coastline is in Namibia, north of the Orange River that defines the border with South Africa. The other half is in South Africa.

Jan 1, 1995

By Stephen J. Navin

The Los Angeles Metro Red Line has installed high density polyethylene (HDPE) as a gas and water barrier around all subsurface structures. The paper reviews the geological setting and resulting need for the barrier. HDPE installation practices are outlined, as are the risks to the barrier, from normal placement methods. Testing and inspection methods used to assure a quality installation are described, and also the field tag method for recording deficiencies and their repair. Specifications and installation changes that will be incorporated into subsequent contracts to improve the quality of the installation are high lighted. The cause of the fire that destroyed part of a tunnel is reviewed as are the revised precautions put in place to prevent a recurrence.

Jan 1, 1991

By M. H. Weinecke, B. P. Faulkner

This paper discusses the process for making lightweight aggregate, the waste materials that make good lightweight aggregate, the chemistry of making lightweight aggregate and the commercial prospects for making lightweight aggregate from wastes. Svedala Industries has been making lightweight aggregate (LWA) from waste materials for the last 10 years. Many claylike materials, such as coal fired boiler ash and washings from a granite quarry, can be used alone or with additional waste materials to produce commercially salable LWA.

Jan 1, 2003

By F. Bourgeois, J. A. Herbst, R. P. King

The ultrafast load cell (UFLC) has proved to be an exceptionally good device for the study of the fundamental processes associated with the impact fracture of particulate material. A new high- sensitivity UFLC has been commissioned at the Utah Comminution Center for the study of low-impact energy single-particle fracture. The force-time histories of individual fracture events have been measured. The force and energy absorbed at crack initiation have been measured at several particle sizes. The mass specific energy for fracture and the associated breakage function have been determined. The distributions of particle breakage energy and particle strength have been measured as a function of particle size.

Jan 1, 1992

By E. D. Seymour

Minera Yanacocha operates a complex heap leach gold facility in the Northern Andes of Peru. Four leach pads and thirteen solution storage process ponds form an extremely complex system. Distinctly different wet season and dry season rainfall accumulations present unique challenges to the process water balance. Minera Yanacocha operates four excess water treatment facilities which discharge water to the environment at specific quality standards in order to maintain a balanced system. Numerous government agencies and non-government organizations are involved with the permitting, monitoring and control of the discharged water. Minera Yanacocha maintains a relationship with 65 villages and communities, with a population of approximately 29,000 people and the city of Cajamarca with approximately 100,000 residents. This paper provides a high level review of the system complexity, the water balance, the excess water treatment facilities and social aspects of solution management.

Jan 1, 2004

By J. C. Stankus, S. S. Peng

Many coal seams are associated with soft floor strata. During mine development, if coal pillars are not properly designed, floor heave occurs and causes interruption of coal production. In the severe cases, the section or mine is abandoned. One method for controlling floor heave is floor bolting. This paper describes the demonstration of flour bolting methods in a West Virginia, info coal mine. Three methods were used: vertical full resin bolting, floor truss bolting and floor truss bolting pins a floor slot at the center of the entry. The design of each method and the experimental results are discussed.

Jan 1, 1995

By William R. Sharp

This paper describes a graphics station and graphics software designed specifically for use within the minerals industry. Through the graphics station, a user is able to recall maps for modification, display them on a color CRT, send the work to a plotter, and restore the work when finished. The engineer may use the system for the storing of data, per- forming engineering calculations, doing word processing, and performing general file maintenance. In addition, the system may be used to communicate with a mainframe computer for such purposes as: transmission of large data files, graphic 3-dimensional rotation of a mineral deposit or mine design, contouring of spacial data, and other data processing work.

Jan 1, 1982

By Boris M. Vorobjev

The paper in question discusses a wide range of topics related to computerized coal mine monitoring systems starting with the history of development and application of computerized monitoring coal mine systems and finishing with modern trends in the design and updating of such systems. The paper focuses exclusively on methodological and technical aspects of computer-based coal mine monitoring systems and their applicability in both surface and underground coal mining operations.

Jan 1, 1989

By P. E. Sperry, J. M. Duncan

INTRODUCTION The purpose of the report on which this paper is based is (1) to evaluate the potential for cost reduction of urban mass transit tunnels by use of alternative materials transport systems during the tunneling process, and (2) to identify research and development program elements to assure that the materials transport system will not become the limiting factor for the rate of excavation. The approach taken was: Review the state of the art of urban tunneling by extensive interviews with representatives of tunnel contractors, equipment manufacturers, government agencies and consultants, and by review of recent literature.

Jan 1, 1979

Bauxite mine rehabilitation is an important stage of today’s bauxite mining activities. To get an overall picture on those activities the International Aluminum Institute (IAI) has been carrying out Bauxite Mine Rehabilitation Surveys since 1991. The most recent survey from 2003 covers 70% of the world’s bauxite production and 23 corresponding companies from 12 countries. The survey activities show that nearly all operations refer to a sophisticated environmental management strategy. By setting up a review scheme based on the principles of the Global Reporting Initiative the compliance of this survey to aspects of Sustainable Development has been reviewed. The Clarification of a multitude of aspects based on the GRI guidelines helped to structure recommendations and relate them to the survey as such but also to the different stakeholders involved.

Jan 1, 2005

By Roger Mourich

As the Powder River Basin coal industry has grown, many changes have occurred in the coal market, the economy and the Basin's methods of dealing with competition in the coal mining business. This article notes the mines that have changed to draglines as the major overburden-stripping tool. The Powder River Basin is defined as those mines within a 97 km (60 mile) radius of Gillette, WY. Mines to the north and south of this area - Decker, Spring Creek, Glenrock - have used draglines more extensively. The reasons for the conversions to draglines at each mine, and the specific timing of these changes, were different. However, the driving factor was economics. As coal production increases, strip ratios increase and coal sales prices decrease, mines must find ways to deal with rising costs and falling revenues. The primary method used has been conversion of overburden stripping to dragline operations. Stripping ratio equals the bank cubic yards of overburden removed for every ton of coal mined.

Jan 1, 1994