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By R. C. Burtan

Long before the dawn of recorded history, man began to dig into the earth's crust in a never ending search for useful materials. It has been well established that prehistoric man discovered flint. "The Flintstones" were aptly named. The flintknappers of southern England and Wales still exist today in ever dwindling numbers as they seek out chunks of flint. It is a well known fact that more than half of the earth's crust is composed of silicon dioxide (SiO2), also known as silica. Silica and silica containing materials have a great many uses in modern society. However, this material is potentially extremely hazardous to our health. Centuries before the Christian Era, Hippocrates wrote of a lung disease common to those who mined in hard rock. It is obvious to us that he was describing silicosis. It is also apparent from ancient writings, that the Egyptians were aware of this malady. Dioscorides also wrote on this subject in the fifth century, B.C. It is undoubtedly the oldest and best studied of the occupational lung diseases. It was certainly described by Agricola in his "De Re Metallica" published in 1556, in which he described lung disease among hard rock miners. This publication, I'm sure, is of special interest and perhaps known to many of you in the mining community. The original document was written in Latin and was translated in 1912 by two gentlemen, Hoover and Hoover. One of these translators was Herbert L. Hoover, a former president of the United States, who made his living before his presidency as a mining engineer.

Jan 1, 1984

By P. Schiavi

A trend towards the independent verification of sustainable development reporting and assessment using third party certification can be discerned in the global minerals industry. Various codes that provide for the third party assessment and certification of performance against a range of externally developed sustainability indicators are being adopted by minerals companies, and there is also considerable activity in the broader area of third party assurance. Using a sociological approach, this paper examines the reasons why third party certification schemes are appearing in the minerals industry to address sustainable development imperatives in preference to other forms of regulation, and considers the broader implications of this trend. Data are drawn from a series of qualitative, in-depth interviews conducted with some of the key players in the development and adoption of certification schemes in the minerals industry, with executive managers of a range of large mining corporations, with representatives of global non-governmental organizations that are active in mining issues, and with government officers responsible for the regulation of mining corporations in Australia. Factors responsible for the emergence of the new certification schemes include: increasing demands from stakeholders for greater credibility in reporting against sustainable development indicators; broader contextual factors including globalization and neoliberal policies; and issues relating to trust and risk. Using insights from our research, and the work of others in this field, we identify some of the critical features of a credible third party certification scheme, and note some of the challenges for the design and implementation of such schemes. We conclude by discussing some of the broader implications of third party certification as an emerging form of regulation in the minerals industry.

Jan 1, 2007

By J. D. Miller

Many factors -- political, environmental and technological -- will determine the extent to which the United States realizes the potential of its vast coal resources. Not the least of these factors is technogical development including mining, processing and transportation. With regard to processing technology, about 50% of the 800x106 tons of coal mined annually in the U.S. is processed in preparation plants. The purpose of the physical separations accomplished in these preparation plants is to remove ash (present as clays and other oxide minerals) and sulfur 'present mostly as pyrite). Coal flotation circuits for such separations are becoming more important in the processing of minus 28 mesh coal. (1,2,3) For example in the U.S. in 1960, 31 flotation plants processed 26,500 tpd; whereas in 1980, there were 80 flotation plants which processed 78,300 tpd. This corresponds to an annual growth in flotation plant capacity of 10 per year during the past two decades. Coal flotation is based on the natural or induced hydrophobicity of coal particles which are separated from hydrophilic ash and sulfur constituents by attachment to air bubbles. The coal particle/air bubble aggregates are collected in a froth phase which is created by the addition of a suitable frother such as MISC. Without exception, such separations are made in a conventional flotation cell, which, in essence, is a stirred tank reactor with a shrouded rotor to shear the air as it passes through a hollow shaft. The dispersed air bubbles (4.0 mm diameter) are stabilized by addition of the frother. Collision of the air bubbles with, and/or precipitation of the air bubbles on, the coal particles results in the formation of coal particle/air bubble aggregates which rise in the gravitational field and are collected in the froth phase developed at the top of the flotation cell. Restraints on successful separation by this conventional flotation technique are particle size and retention time. Generally it is found that effective flotation is only achieved for particle sizes between 10 and 1000 microns. Further, with respect to retention time, it is found that a nominal retention time of at least 2 minutes is required for successful separations. These facts limit the effectiveness of conventional coal flotation. Coal fines may be lost in the reject stream and disposal is frequently a problem. The retention time required for conventional flotation results in large floor space demands which limit the capacity of the plant.

Jan 1, 1981

By William F. Ryan, Paul T. Gribbon

With the rise in construction claims in public works contracting over the years, the use of Dispute Review Boards (DRB’s) in underground construction contracts has become quite common. However, in order for the DRB process to be an effective tool, there must be complete trust and confidence in the Board members and their adopted procedures by both the owner and contractor. This can be difficult in an industry where Board members and contractors may be well known to each other, while an owner maybe involved in a large complex underground project only occasionally. Using case histories, this paper will discuss some recent experiences with the DRB process from an owner’s perspective.

Jan 1, 2003

By Peter Jackson

Over a quarter of a century ago a New Zealand physicist suggested the possibility of detecting coal seam discontinuities by a seismic method carried out underground in the mine workings (Evison 1955). Twenty years ago initial experiments were performed in Germany (Krey 1963). Since then research has continued, notably in Britain and Germany, in order to provide a reliable fault and washout detection system. The National Coal Board of Great Britain has now carried out more than 250 surveys in Britain, France and Australia. The first NCB survey in the U.S., a successful application of the technique to an Ohio coal seam, will be described and the strengths and limitations of the method explained.

Jan 1, 1984

By C. R. McKee

In-situ mining of hard rock deposits will only become successful as we understand the engineering parameters involved and the design limitations they impose. As recognized by Wadsworth1 the most critical area is the enhancement of permeability in a hard rock mass. Along with creating permeability, the appropriate flow and fragment size conditions must be generated to insure economic rates of mineral recovery. In this article our interest is confined to true in-situ processes in which boreholes are drilled from the ground surface or a mine drift to deeper strata. We assume that fractures and permeability enhancement will be due to explosives detonated in boreholes. Other techniques such as hydraulic fracturing do not produce the necessary size distribution to promote economic extract ion rates unless the medium is already highly fractured and interconnected. Notable exceptions where hydraulic fracturing is applicable are many oil, gas and salt deposits. For many in-situ processes, an array of explosive charges offers the opportunity of creating a distribution of many fractures not achievable by other techniques. Such a situation would be suitable, for example, to in-situ mine hard rock gold, uranium, copper or oil shale deposits and may enhance oil and gas recovery in certain situations. The purpose of our article is to review and extend the explosive permeability theory of McKee and Hanson 3,4,5 and to apply its results to derive design parameters suitable for in-situ mining.

Jan 1, 1981

By Donald E. Hendrickson

A new prinicple of side dumping front end loading for underground mucking machines has completely changed the concept of underground loading and haulage equipment arrangement both in production and development work loading. Versatility and adaptability of this type of machine permits combinations with a broad range of haulage means not possible with -conventional overhead loaders. Steel "armored" conveyors serving this type of loader are replacing conventional rail mounted car haulage to give a continuous loading operation and effect important economics of reduced manpower, faster loading rates and fewer working areas for a required production. First used in Germany this easy to control and highly efficient means of placing rock from the muck pile on or into haulage means has advanced the art of underground rock loading more in the past three years than any other advancement since the first successful small crawler mounted air powered loader was introduced in 1954. Bucket type loaders with a relative new side dump principle are gaining in popularity for underground loading. They are replacing conventional overhead loaders in present applications and becoming first choice in new ones. Primarily for hard rock development and production loading they are also widely used in production loading of coal and other soft materials. This discussion briefly traces the historical development of hard rock underground loaders to the new side dump type and its present population. In more detail various applications, loading techniques and the advantages of operation, production and economy with the side dumper in hard rock loading will be dealt with.

Jan 1, 1966

By R. Bhaskar

The results of an experimental study on the dispersion and deposition characteristics of fine coal dust in mine airways are presented. Experiments were conducted at various flow velocities using bituminous and semi-anthracite-coal dust which had a large proportion of dust in the respirable size range. Cross sectional variations in the concentration of dust at various points in the airway were also measured. Instruments used in the experiments included gravimetric samplers and impactors. Concentration measurements were made both for the respirable and total airborne dust. The experimental design, sampling procedures and results are discussed. The study is aimed at providing a better understanding of the temporal and spatial behavior of dust particles in underground mine airways.

Jan 1, 1986

By K. S. E. Forssberg, M. I. Hallin

In many cases, the reuse of process water in flotation plants is desirable both for plant operating reasons and for environmental protection. The main advantages are better housekeeping of fresh water and process chemicals together with the reduction of polluting species to the environment. There are however a number of problems involved in the use of recycled process water. The main problem is that recycling sometimes has a deterious effect on the process and can occur months after the start of water recycling. The Division of Mineral Processing of Luleå University of Technology has been conducting experiments on recycling of process water at various sulphide plants in Sweden for over ten years. The experiments have been carried out in pilot- and full industial scale, in collaboration with the mining companies operating the plants. Until 1988 investigations were carried out in four different sulphide plants. The objectives of the experiments were: first to document differences in the composition of the process water during recycling; secondly to investigate any changes in the pulp chemistry of the flotation circuits wich may be due to the influence of recycled water; and lastly to establish critical levels, if any. of the parameters measured. While conducting experiments of this kind several things have to be kept in mind. Normally, recycling is done by using tailings pond water as process water. This means that time effects are important, because of the time lag between water input in the tailings pond and the reclaim of that water back to the plant. As will be shown, the

Jan 1, 1989

By M. G. Mudrey

Considerable potential for metallic mineral resources in the lower Proterozoic rock of the Lake Superior region exists (Mudrey and Kalliokoski, in press). Most of the identified resources occur within a 2.0- to 1.9-b.y.-old lithotectonic assemblage characterized by extensive sedimentary strata in the north and thick volcanic se- quences in the south, all deposited on a two-terrane, composite basement of Archean age (DeMattis, 1989). Since the late 1960s, measured resources of nearly 90 Mt (100 million st) of typical volcanogenic massive sulfide at eight localities in Wisconsin have been discovered. The largest of these, near Crandon, contains about 61 Mt (67 million st) of ore averaging 5.6% zinc, 1.1 % copper, and 0.5% lead. Although none of these properties are in production, estimates by Mudrey (1978) suggest that Wisconsin could become a major contributor of newly mined zinc and copper in the United States. These discoveries and uranium and gold discoveries in the Canadian Precambrian are what have led to in- creased metallic mineral exploration throughout the northern half of Wisconsin (Fig. 1). In this chapter, we discuss the geology and legal framework in which the Proterozoic volcanogenic massive sulfide deposits were found. Exploration activities for other metals have generally been negative, and have been background noise for the legislative activities related to the massive sulfide discoveries. Uranium exploration has been consistently negative, although several different environments have been assessed. Other metal discoveries. such as titanium/vanadium, have been subeconomic.

Jan 1, 1991

By G. Ferrara, P. Bozzato, B. Chinè

To obtain a reliable comparison between conical and cylindrical separatory vessels used in dynamic dense-medium separation systems, the following two studies were made: a study of the swirling flow in conical and cylindrical vessels using laser-Doppler velocimetry (LDV) and a study of the behavior of suspensions of magnetite and ferrosilicon in water in both separators. It was found that the tangential velocity profiles differ in conical and cylindrical vessels. In a conical cyclone, free vortex conditions affect the largest part of the vessel, while in a cylindrical vessel, the motion approaches that of a forced vortex, i.e., that of a centrifuge. It was also found that the conical vessel manifests higher centrifigal acceleration and very strong densifying (the density differential) and, hence, the density gradient inside the vessel is large. It was found that the cylindrical vessel manifests lower centrifugal acceleration and low densifying, i.e., low-density differentials, and hence, the density gradient inside the vessel is small. Also, due to greater densifying, the density cut-point in cyclones is higher than the operating medium density, while, in cylindrical vessels, the density cut- point is closer to the medium density. The results provide an interesting description of the differing behaviors of conical and cylindrical vessels, and they help explain the differences in pegormance between the two types of separators.

Jan 1, 2000

By R. M. Campoy

In this review of the copper, lead, zinc, and molybdenum industries in Mexico, the author describes how the country's position in the world base metals market and the climate for foreign investment in Mexico have been affected by the nationalization of the banking industry in that country and by recent mining legislation and the current national debt crisis.

Jan 1, 1988

By R. Bhaskar

The results of an experimental and theoretical research study into the spatial and temporal behavior of dust in mine airways is summarized in the paper. Experiments were performed in mine airways under both controlled and normal operating conditions. The controlled experiments included the documentation of the concentration and deposition patterns for two types of dust under three different velocities. Real-time dust concentration data were obtained using Real-time Aerosol Monitors (RAM-I) to determine the dispersion coefficient in a mine airway. On the theoretical front, a convection-diffusion model of the dust flow phenomenon in mine airways was developed considering dominant mechanisms affecting dust transport and deposition in mine airways. Mechanisms modeled include turbulent and gravitational deposition, coagulation, and dispersion.

Jan 1, 1988

By Robert Blair, David L. Fey, Stanley E. Church

Determination of the pre-mining geochemical baseline in bed sediments in watersheds impacted by historical mining activity is important in establishing watershed restoration goals. We have developed methods to solve this problem in the Animas River watershed, southwestern Colorado, using geomorphologic mapping to identify terraces that contain pre-mining sediments. Following a systematic evaluation of possible sites, we collected samples of pre-mining sediments in gravel deposits from 21 sites throughout the watershed. Geochemical analysis of individual layers has produced a chemical stratigraphy that can be tied to the historical record through geochronological and dendochronological studies. Analysis of geochemical data, when coupled with the historical record, clearly shows that there has been a major impact on the geochemistry in bed sediments in the active stream channel by past mining activities. Historical mining has resulted in a substantial increase in metals in the very fine sand to clay-sized component of the bed sediment of the upper Animas River, and Cement and Mineral Creeks, which are the major tributaries of the Animas River. Enrichment factors for metals in modem bed sediments, relative to the pre-mining sediments, range from 1 to 6 for arsenic, 1 to more than 10 for cadmium, 1 to about 15 for copper, 1 to more than 25 for lead, 1 to more than 10 for silver, and 1.6 to more than 12 for zinc. The pre-mining bed sediment geochemical baseline is high relative to average crustal abundance values of many metals. The Animas River watershed above Silverton, Colorado would be readily identified as a highly mineralized area suitable for mineral exploration if it were not disturbed by mining.

Jan 1, 2000

By Raymond E. Kary, John W. Mcklveen

The four unit Cholla coal fired power station at Joseph City, Arizona, consumes coal from the McKinley mine located in western New Mexico. Since coals may contain relatively high uranium or thorium concentrations and may release quantities of detrimental progeny of these elements to the environs, there is concern that releases may pose an adverse environmental impact or even a health hazard to the workers. Thus, an effort was made to quantify the radionuclide content of the coal and compare the results with radionuclide concentrations already present in the vicinity of the plant. Additionally an attempt was made to assess any potential for significant enhancement of the levels of radioactivity in the environment or to plant personnel. Background gamma radiation measurements at and near the plant ranged from 8 to 12 [µ]R/hr (70 to 105 mR/yr) with a few localized anomolies measuring to 18 [u]R/hr (160 mR/yr). Levels on top of the coal storage piles decreased to ~ 6.5 [u]R/hr (60 mR/yr). Apparently the direct radiation emitted from the coal is less than the background levels in the vicinity of the plant. Measurements performed on top of several coal seams at the mine confirmed low radiation levels emanating from coal, but readings more than doubled when the overburden was monitored. Laboratory gamma spectrometry confirmed the lower amounts of natural radioactivity in the coal when compared against soil and water samples obtained in the vicinity of the plant and the overburden at the mine. In an effort to see if there is biological enhancement, animal feces was sampled. The radiation variations were found to be influenced primarily by naturally occurring potassium-40 which varied from ~ 1 to 18 pCi/gm rather than fluctuations in the uranium and thorium series. The potassium-40 concentrated in the ash were similar to the concentrations in the environs around the disposal ponds while Radium-226 concentrated in the fly ash was ~ 3 times that found in the immediate surroundings. Radon-222 gas concentrations in buildings at or near the plant ranged from 0.5 to 1.8 pCi/l and were generally lower than indoor concentrations measured in the Phoenix area. The burning of coal at the Cholla station does not appear to increase ambient levels of radioactivity found in the surrounding environs or to the workers. However, the use of byproduct fly ash for construction purposes may need to be examined.

Jan 1, 1981

By Hubert E. Risser

At the outset of a discussion on the adaptability of Illinois coals for use in iron and steel production, it is perhaps well to define terms. ?Adaptability? as used in this context, means that a coal can be, adapted to use within a given technological and economic framework. For a coal to be adaptable, to use in the manufacture of metallurgical coke within the present technological and economic framework, it must possess, among other things, at least the following characteristics: 1. The coal must be capable of producing, alone or in combination with other coals, a coke that can meet at least a minimum standard of required performance in the present-day blast furnace. The coke must have sufficient strength, stability, hardness, and freedom from impurities to make it suitable. 2. If the coal in its raw form does not meet these requirements, it must be amenable to beneficiation or upgrading so that the requirements can be met. 3. It must be available in uniform quality and in sufficient quantities to meet the need. 4. Use of the coal must be economically attractive. If its quality is equivalent; to that of the coals with which it must compete, it must be no more expensive than they. If It is better, a premium price may perhaps be demanded. If, in any respect, it is the least bit less suitable, the cost must be lower to offset its disadvantages.

Jan 1, 1961

By Robert E. Moore

Investigators have attempted to develop lime refractories on a scale for broad applications in the metal and ceramic industries for several decades. There was a flurry of activity in the early to mid-fifties but no commercial developments were forthcoming. The literature of that period yields little information on plant trials. A major factor suppressing past interest in lime has to have been the high success with the application of magnesic and dolomitic materials. These materials, usually tar-bonded or impregnated, have become the refractories success story of the past two decades, especially in BOF applications. It is safe to say that their development and application has essentially plateaued, and that work today is focussed on finding cheaper paths to produce MgO-based refractories. For example there are efforts underway to extract MgO from mineral magnesite and to combine natural dolomite with MgO1. Beginning in the late sixties, rather intensive research began on the development of CaO brick, especially in East and West Germany, in Poland, and other communist bloc satellites, 'and also in Italy and Spain. One speculates that the motivation was a regional shortage of good magnesia and dolomitic material. Of course, There has always existed the prospect of cost savings should it be possible to use raw limestone as the starting material. Quite a large literature has appeared treating of these developments which in the early seventies had already reached full plant scale trials and uses. Some of the directions followed in the research have led to novel methods of brick manufacture.

Jan 1, 1985

By Raphael Mourad, Colin R. Phillips

Fluorescence, radioluminescence, phosphorescence and thermoluminescence in TLD 100 and 700 are discussed and compared. The energy budget in thermoluminescent material is presented in general terms. Results of measurements of radioluminescence, phosphorescence and thermoluminescence in LiF:Mg irradiated with [a] radiation, using simple facilities, are presented. The calculated energy budget in the exposed chips using [a] radiation is compared to published data using [y] irradiation.

Jan 1, 1981

By K. I. Cunningham, C. S. Spirakis

Two types of native sulfur deposits have been found in Lechuguilla Cave: thin late-stage crusts and massive early- formed deposits. Most, if not all, of the crusts appear to have formed by remobilization of native sulfur contained within gypsum and sulfur masses. The process is occurring today and is slowly converting the sulfur to gypsum. The absence of primary gypsum or reductants in the cave indicates that the early-formed massive sulfur deposits did not form by in-place reduction of sulfate, which is the process that formed the commercial sulfur deposits in the Delaware basin. Instead, it appears that H2S dissolved in basinal brines was oxidized by oxygen in near-surface ground waters in the cave. Fluid- inclusion data, which suggest the presence of both fresh water and saline water as the sulfur formed, support this interpretation. Although individual sulfur deposits in Lechuguilla Cave are no more than several tens of metric tons, the abundance of secondary gypsum (as much as 10 meters thick) indicates that native sulfur may once have been much more extensive.

Jan 1, 1992

By Sandip K. Mukherjee

This paper describes the application of pressure foam to control respirable dust in a double-drum longwall mining section. The feasibility of passing an adequate quantity of pressure foam through the shearer drum was initially established in the laboratory. Thereafter, underground testing of the foam system to determine its effectiveness on an active operating longwall was conducted in a mine in West Virginia. The foam system proved superior to the water spray system. The de- tails of the laboratory and field investigations, the results obtained, and the degree of acceptance of this system by the mining company are discussed in this paper.

Jan 1, 1984