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By David M. Miller, Pramod C. Thakur, Larry D. Taylor

The most common technique used to suppress respirable coal dust in air is that of spraying with fine water particles. The water droplets are typically much larger than respirable dust particles and they collect dust particles mainly by interception. Dust collection efficiencies can be improved by reducing the droplet size and in- creasing the droplet velocity. This is typically done by reducing the surface tension of water and increasing the water pressure. Dust collection efficiency can be further improved by in- creasing the electrical attraction between the water and dust particles through electrostatic charging. A technique developed by Conoco accomplishes both surface tension reduction and electrostatic charging by discharging weak solutions of surfactants in water at high pressures, 13.8 to 27.6 MPa (2000 to 4000 psi) in an intrinsically safe manner. The paper de- scribes the process and presents related dust suppression data.

Jan 1, 1986

By Nora M. Hutt, Kevin A. Morin

One technique for controlling ongoing acidic drainage is to relocate and submerge net-acid-generating waste rock in a lake or water-retaining impoundment. This can lead to the overall improvement of water quality and the reduction In short-term environmental liabilities. A case study of this technique is the Eskay Creek Mine in northern British Columbia. Some findings of the study are: (1) the addition of lime to each truckload of rock, based on its rinse pH, neutralized the accumulated acidity and suppressed the accumulated-metal release, (2) only 10-20% of the dump's neutralization potential had been consumed when acidic drainage appeared, (3) water chemistry in the watershed recovered roughly three years after relocation, and (4) environmental liability was reduced due to the cessation of on-land acidic drainage with no degradation of lake chemistry.

Jan 1, 2000

By Andrzej M. Wala

A prototype expert system for planning and designing an underground coal mine has been developed in a doctoral study at the University of Kentucky. This prototype expert system for underground coal mine planning and designing consists of a number of knowledge bases concerning different elements of design (e.g., ground control, excavation and bulk materials handling, ventilation, etc.). The objective of this paper is to present the development process of the ventilation design knowledge base for this prototype. This expert system prototype is intended for building an instructional expert system for underground coal mine design. Therefore, the undergraduate course on mine design has been used as the basis, for its development. Because of the availability of knowledge and expertise, this research study has been limited to development of a knowledge model for the Appalachian coal mining region.

Jan 1, 1993

By D. G. Millette, A. J. S. (Sam) Spearing

The design of a cost effective backfill system involves many aspects and various inputs from different engineering disciplines. Backfilling is a very significant mining cost and efforts need to be made in the design stage to maximise efficiency and flexibility whilst minimising costs. The aspects that need to be considered include the following: Required fill performance underground Peak and average fill tonnage requirements Backfill scheduling in the mining cycle Material selection, testing and preliminary costing Plant design and storage needs Infrastructure requirements Implications on surface waste/tailings disposal and costs Total backfill costs In order to produce a cost effective and efficient backfill operation, a multi-disciplinary project team is required that should include the following skills and functions: Mine Planning Rock Engineering Metallurgy Mechanical Engineering Environmental Health and Safety Tailings Disposal/Waste Management This paper discusses the above and indicates important aspects that should be considered.

Jan 1, 2001

By K. Gum, W. C. Hirt, D. A. Rice

Selective flocculation was used to produce a superclean zinc concentrate by minimizing silica contamination. Research was carried out on a flotation concentrate from the Jersey Miniere Zinc Company (JMZ) in Gordonsville, TN. The material was first dispersed with sodium silicate and then causticized tapioca starch was used to selectively flocculate the sphalerite, leaving the silica in suspension. This technique has been applied commercially to iron ore beneficiation but never to zinc processing. The feed material assayed 0.45% SiO2. The use of 0.56 kg/ t (1.13 lb/st) sodium silicate and 0.070 kg/t (0.141 lb/st) causticized tapioca starch resulted in a 98.2% zinc recovery and produced a purified zinc concentrate assaying 66.0% Zn and 0.24% silica. The target level for silica contamination in JMZ zinc concentrates is currently 0.30% Si02. This work demonstrated that selective flocculation is a potential method for cleaning flotation concentrates, particularly where low silica products are required.

Jan 1, 1995

By J. N. Economopoulos

The mining industry is becoming increasingly aware of environmental issues and has made big forward steps in the field of environmental management. Legislation, social pressure and competition introduced changes in the industry?s policies and practices in order to conform to the new standards of environmental performance. The paper addresses the need for an integrated and systematic approach to the issues of environmental management within the mining industry.

Jan 1, 2002

By Todd A. Duex

The Richmond Hill Mine has recently completed a reclamation plan to mitigate Acid Rock Drainage (ARD) which was identified at the toe of the former waste rock pile in 1992. Reclamation activities began in 1994 with the removal of ARD material from the waste rock pile and placement of this material in the former pit. This material was then isolated from the near surface environment by a low permeability capping system designed to minimize water and oxygen flow into the material. The capping system consists of, from bottom to top, six inches of limestone, 18 inches of low permeability clay liner, 4 and one-half feet of thermal barrier/drain layer, and six inches of topsoil. This capping system was completed in 1995. An extensive program is in place to monitor the effectiveness of the reclamation plan, and includes measurements on moisture content movement, temperature, oxygen content, and groundwater impacts. Monitoring has been ongoing since the completion of reclamation. This monitoring plan is demonstrating the success in isolating the material from the near surface environment and minimizing the impacts to the surrounding environment.

Jan 1, 2000

By J. K. Mohanty, D. Panda, P. K. Sahoo, R. K. Paramguru, K. C. Nathsarma

Ferromanganese slag, a product of the manganese industry, was characterized mineralogically. The slag, which contains high Mn values, was characterized using optical microscopy, XRD analysis and electron microscopy. No separate Mn-bearing oxide mineral phase was found. The slag is amorphous, and no crystalline phase was identified in the hulk sample by XRD, However, in. fine fractions, quartz was identified. Scanning electron microscopy (SEM) revealed the presence of Mn, Si, Al and Ca in the matrix without the development of a mineral phase. Leaching experiments using H2SO4 were carried out to determine if Mn could be extracted from the slag. At room temperature, almost 100% of the manganese could be dissolved at a solid-liquid ratio o f 1:10 by leaching with dilute sulfuric acid. The impurities could be precipitated by pH adjustment to produce a manganese sulfate solution suitable for the production of MnO2 or electrolytic Mn metal. Based on the laboratory-scale experiments, a suitable process is proposed to recover manganese values from the, ferromanganese slag.

Jan 1, 1999

By Richard Engelmann

The mining industry, in particular the coal industry, has experienced the implementation of some major environmental regulatory programs during the past two decades. Over the coming decade the coal industry will probably experience only "fine tuning" of the regulatory programs they now operate under. The rest of the indus- try, however, appears to be on the verge of coming under a major new regulatory effort by the Environmental Protection Agency. Litigation and resulting court decisions will be the main force driving further changes in the SHCRA (Surface Mine Control and Reclamation Act) regulatory program. These changes are anticipated to be minor in compar- ison to earlier changes. EPA, however, is preparing a regulatory program which may carry as much impact to the rest of the mining industry as SNRA was to coal. Details of this program have yet to be worked out. Changes in the way EPAts Clean Air Program is applied to mining could also significantly impact the mining industry.

Jan 1, 1989

By F. M. Swain

High-calcium limestones occur in the upper part of the New Market Formation, of Lower Middle Ordovician age, in Franklin and Cumberland Counties, Pennsylvania. The high-calcium facies of the New Market Formation is represented by sublithographic limestone or vaughanite, which probably formed in quiet water; low-energy environments such as intershoal lagoons, or in protected bays similar to the present-day Florida Bay environment. Rapid facies changes are characteristic of the strata. The better grade of stone lies in the upper 100 to 125 feet of the New Market Formation and averages 95-97% calcium carbonate. Silica and magnesia are about equal in amount as impurities. One high-calcium belt extends from the Maryland state line through Chambersburg and Newville to beyond Carlisle. The strata in this belt are structurally complex, which requires careful field study' and core-drilling prior to exploitation. Stone suitable for blast-furnace flux is present in relatively large amounts, but stone for open-hearth use or portland cement requires more selective quarrying.

Jan 1, 1966

By I. Longson

Maintaining control over underground environmental conditions in the United Kingdom is increasingly dependent on the contribution of underground booster fans. Given the recent trends of higher rates of production from a fewer number of coal faces with higher levels of mechanization and higher power consumption, the effect has been to place a greater load on the mine ventilation system. This has increased the scale of potential problems that may arise should any of the main ventilation control devices not perform at the required full duty. This is particularly true for underground booster fans. Major changes occur in the main ventilation parameters on the stoppage or restart of a booster fan which results in a temporary loss of environmental control. This paper analyzes the impact of such events and details a mathematical model thar has been developed for a single-mesh circuit containing a main and a booster fan. Predictions based on this simple model are presented and discussed with particular reference to the energy changes occurring within the ventilation system immediately following a booster fan stop or restart

Jan 1, 1995

By J. E. Hoffman, Massimo Maccagni, T. J. Keefe, Marco Olper, O&apos

The problem relating to the use of insoluble anodes in acidic and highly aggressive environments has still not been definitely solved, and it is therefore a recurring subject of discussion. The fields of application in which insoluble anodes play a fundamental role are mainly in the electrolytic extraction of metals, in cathodic protection with impressed current, and in the production of oxidized halogenated salts. Based on the foregoing, B.U.S Engitec Servizi Ambientali (BESA) developed an electrode suitable for the use in the above-mentioned system. The basic component of the BESA anode is a bimetallic wire made of a copper rod (core) covered by a thin layer of valve metal, to be chosen between tantalum (Ta) and niobium (Nb). The wires, coated with suitable catalyst (PbO2, Pt or others) are inserted in a plastic frame and fixed to a current feeder by means of a screw, ensuring an optimal contact. Experimental data on the operating conditions, such as kind of electrolyte, current density, electrode potential, corrosion tests and fields of possible application, are described.

Jan 1, 1993

By E. M. Van Eeckhout

The National Uranium Resource Evaluation Program (NURE) has produced a mass of geochemical data in the form of data files on tapes. This paper presents a methodology for utilizing those tapes in a simple, practical manner. An example is given of an analysis of the Butte quadrangle, Montana, tape obtained from the Los Alamos National Laboratory (LANL). The example details the sequence of splitting the data file, plotting histograms, cumulative frequency curves, concentration plots, and methods for evaluation. All programs are written in FORTRAN. The case study was performed using a mini- computer (DEC PDP 11/70) and standard plotting subroutines.

Jan 1, 1982

By D. Dimitriadis, T. Polglase, M. M. Botz, W. Phillips, R. Jenny

Cyanidation processes for the extraction of gold or silver frequently involve the processing of sulfurcontaining solids that react with cyanide to form thiocyanate. The formation of thiocyanate is an undesired side reaction, and in many cases thiocyanate formation results in a prohibitively high cyanide consumption. With the increasing number of gold and silver mining projects that involve the processing of sulfide ores or concentrates or that utilize a biological sulfur oxidation process, more attention is being focused on minimizing thiocyanate formation and in treating solutions to eliminate toxicity associated with thiocyanate. Though not yet commercially applied, there are several processes available to recover cyanide from thiocyanate to reduce tailings toxicity and to allow the reuse of cyanide otherwise lost to thiocyanate formation. This paper presents an overview of processes available for recovering cyanide from thiocyanate along with estimated operating costs for the processes. Pilot testing data suggests that in some cases cyanide can be recovered from thiocyanate for approximately the same cost as newly purchased cyanide.

Jan 1, 2002

By Robert E. Goodwin

There are four main requirements which must be considered when selecting a wire rope for the best serviceability. A proper choice is made by correctly estimating the relative importance of each of these requirements and selecting s rope which has those qualities best suited to withstand the combination of destructive forces expected under continued service. A wire rope should possess: 1. Strength sufficient to support the maximum load expected and with s proper safety factor. 2. Ability to withstand bending and to resist bending fatigue without failure of the wires. 3. Ability to withstand surface abuse such so abrasive wear, pounding, and wire scrubbing. 4. Ability to withstand abuse such as crushing and distortion.

Jan 1, 1968

By C. Ceccarini, I. Salvadori, G. Oggiano

GENERAL BACKGROUND The first mention of the presence of bauxite in the mesozoic series of north-west Sardinia (fig. 1) is owed to Oosterbaan, a Dutch geologist, who carried out a geological survey of the area in the ninetten thirties. A more detailed study of the mesozoic series was attempted in the fifties by Pecorini and other, who concentrated particularly upon the stratigraphy of the bauxitic horizons, through examination of the various outcrops. In the sixties a pining company, Monte Amiata S.p.A., turned its attention to a section of the deposit outcropping near Olmedo and, considering it to be of some promise, carried out prospecting works consisting essentially of various trenches, some bore holes, a few adit and a. layout plan for the preparation and execution of trial exploitation. The results, although positive, did not convince the company's shareholders to continue the exploration. This report, which is intended as a new contribution to knowledge of the Sardinian bauxite deposit, takes into account the information acquired not only from a drilling prospection begun in 1979 in connection with the SOMIT-PROGEMISA joint venture, but also the results of structural studies and numerous chemical, mineralogical and

Jan 1, 1984

By Isobel Clark

Geostatistical methods of estimating ore reserves and other spatial phenomena are becoming increasingly wide spread in their use. Properly applied, Geostatistical estimation falls into two stages -- the "modelling" of the spatial variability within the study area; and the use of this spatial model to provide an appropriate estimation technique. The first stage usually consists of construction and interpretation of semi-variogram graphs, and the second is the development of the corresponding Kriging method. Because of the apparent subjectivity inherent to the first stage of a geostatistical analysis, attempts have been made to provide methods of "testing' whether a particular semi-variogram model (say) adequately represents the study area. Increasingly, the choice of model is being justified by a process known as "Cross Validation'. With this approach, the analyst uses a partial data set to estimate values at actual sampled positions. "Real" and "estimated" values are then compared in such a way that the model can be accepted or rejected. This paper discusses the process of cross validation in some detail, using case studies as examples. Some problems with the technique are illustrated and discussed.

Jan 1, 1986

By H. R. Weischedel

The art of wire rope inspection has advanced rapidly over the past decade. Present electromagnetic (EM) wire rope inspection instruments provide an important and often vital element of wire rope inspection. Some instruments are easy to operate and offer simple and clear data interpretation. Simultaneously, wire rope inspection and retirement standards are becoming simpler and more lucid. Future guidelines will he easy for inspectors to apply and for rope operators to fulfill. The thrust of evolving regulations is clearly toward periodic EM inspections supported by visual inspections. These development sallow even moderately skilled personnel to perform EM inspections of wire ropes. Therefore, it is now possible and cost effective for wire rope users to have EM and visual inspections performed by in-house personnel. In-house EM inspections have many advantages and offer an excellent return on the initial investment. Since EM inspections can detect rope deterioration in its beginning stage, wire rope users recognize that they are an effective preventive maintenance tool. For instance, the early detection of wear or corrosion allows immediate corrective action. This can easily double, or even triple or quadruple, the service life of a rope.

Jan 1, 1991

By Allen M. Newcome

The Ohio valley division of consolidation coal company has incorporated two new aspects within its coal mining concern. A new communication system, thru the cooperation of the c. & p. Telephone company, has been established in each of our mines with its central control in the general office building. In conjunction with this system, a Texas instruments 960 a computer has been incorporated into the system. The purpose for our computer is to provide modernization and improvement to our safety, production and maintenance programs. Thru proper use, the computer will help eliminate inaccuracies and inefficiences that have previously caused inaccurate analysis of problems. Due to federal requirements for more reliable communications in underground mines, Ohio valley division is making a concentrated effort to improve its communication systems. Systems such as the magneto phone and trolley phone have been looked at more critically. It was found that these systems are being used well beyond their limits. With these facts in mind, division personnel started looking for a system that would have these built in advantages: ease of maintenance and installation, increased reliability, low cost, and an inherent ability as a multiple use system.

Jan 1, 1975

By C. Maltesh, P. Somasundaran, G. A. Gruber

Anionic conditioning of phosphate ores prior to fatty acid flotation is a critical step that determines the selectivity, recovers and, hence, the economics of the process. However, the chemical mechanisms operating during this conditioning step are not very well established. In this work, a comprehensive surrey of plant practice was conducted. Then, adsorption on flotation feed and francolite were studied under simulated plant conditions. Different adsorption mechanisms were found to be dominant under laboratory and plant conditions. In plant water, there was sonic physisorption of oleic acid on phosphate flotation feed and francolite, in addition to chemisorption. However, in distilled water under laboratory conditions, only chemisorption was detected. Fuel oil reduces the residual oleic acid in solution after adsorption, which explains the beneficial role of extender in phosphate flotation. The dissolved species in solution arising from the flotation feed or plant processing water are shown to clearly play a major role in determining the adsorption of oleic- acid on the substrates. The study also specifically demonstrates that, for the results to be used commercially, it is important to conduct the tests under plant mixing conditions and with the same plant water chemistry.

Jan 1, 1997