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By R. D. Lord

This paper deals with the search for the best practical means of storing sulphide bearing tailings, where there is no residual excess of carbonate material. It is the common experience that the sulphide content decomposes, with the aid of bacterial action, and the resulting sulphuric acid escapes, along with any heavy metal solutes, through embankments that are usually porous to some degree. The problem is typified in the tailings of the uranium operations of Elliot Lake, Ontario, where mining started some 20 years ago. The approach to tailings disposal paralleled the practice for other hydrometallurgical plants treating gold and base metal ores. Impoundment areas were designed to retain solids, and a clear and neutral overflow was considered satisfactory practice. Now experience has shown that these areas, some idle for over a dozen years, release acids, in seepage and overflows, to an unacceptable degree. To protect natural water courses neutralizing plants are operated wherever required. Lime slurry is fed continuously into the tailings outflows in a quantity sufficient to raise the pH to 8.5 and precipitate heavy metals that may be in solution. The objection to this procedure is that the plants will require servicing indefinitely, unless a better remedy is found.

Jan 1, 1975

By James W. Guider

Of all the technology available to the iron blast furnace operator, raw materials preparation is by far the most important. Superior raw materials have been basic to the success of the Japanese steel industry, and they are just as essential to the American steel industry in winning its competitive battle against foreign government subsidized steel imports. Therefore, the mine operator and the ore beneficiation engineer must strive to produce the highest quality raw materials possible to meet the precise demands of the modern blast furnace and steel plant.

Jan 1, 1978

By W. J. Mahoney

A good quality assurance program at a coal mine or power plant is accurate, timely, and consistent. The quality analysis is accurate due to a complete sampling of the coal stream loaded into the unit train. The sample analysis is accurate because standardized testing procedures are applied. Once the analysis is completed, the results must be communicated to the electric utility in a timely manner. The electric utility needs the results to better manage the coal inventory at the power plants. A quality assurance program can also help the mine deliver a consistent product to the electric utility's power plants. The importance of the three major tenants for a good quality assurance program: accuracy, timeliness and consistency, are based on major changes that are taking place in the electric utility industry.

Jan 1, 1994

By Sheldon P. Wimpfen

Under the Wilderness Act of 1964 and the accompanying House Conference Report, the Geological Survey and Bureau of Mines are charged with the responsibility of making recurring mineral studies of wilderness and wilderness candidate areas in national forests within and proposed for the National Wilderness Preservation System. The Wilderness Act, a major shift from the multiple-use concept of national forests, identified for the first time the value of mineral resource information in decisions for single-use designation of public lands. This concept was further realized when the Secretary of the Interior in May 1974 recommended that mineral studies be made prior to wilderness recommendations for five large Interior-managed game ranges and the Glacier Bay National Monument aggregating 7.8 million acres. Presently, our studies have been completed on 126 wilderness and proposed wilderness areas totaling 15.4 million acres in the national forests. In 1973, 1 year in advance of the act's 10-year review deadline, we completed the 34 primitive areas, originally the only potential additions considered by the 1964 Act.

Jan 1, 1975

By Jon P. Stone

The Automated Minerals Information System (AMIS) is an integrated data base system being developed to support the Bureau of Mines minerals information collection and analysis activities. The system facilitates cross-referencing and integration of domestic and foreign information from a variety of sources. The AMIS provides a central source of minerals information that is versatile and responsive to the needs of problem and policy analysts as well as supporting the needs of those involved in data collection and interpretation. As the AMIS becomes fully implemented, it will become an important tool in forecasting and assessing the impact of policy decisions that affect the supply and demand for minerals. The Bureau of Mines has long been the Federal Government's principal source of worldwide information on non-fuel minerals. Emphasis is placed on the analysis of mineral problems and policies as they affect the world's nonfuel mineral resources. To facilitate timely and accurate analysis, comprehensive data on 87 commodities are collected by various Bureau programs. Minerals information is made available through a number of periodic publications including the annual Minerals Yearbook and monthly Mineral Industry Surveys. These data collection and analysis activities have traditionally been supported by over 200 separate information processing systems. The Bureau of Mines has begun to implement a broad information strategy to provide a better response to the mineral problems and issues of the 1980's. The cornerstone of the Bureau of Mines information strategy is the development of the Automated Minerals Information System. When fully operational, we believe that the AMIS will provide the Bureau of Mines with the most comprehensive source of minerals information available anywhere in the world.

Jan 1, 1982

By K. Pietruszka

The article presents the concept of the application of the Finite Element Method (FEM) and ABAQUS software in the global monitoring of changes in the rock mass and on the surface of the area, as a result of backfilling the workings. Waste materials applied for stabilizing old mining workings can have a strong influence on the rock mass and surface. According to the regulations, this process should be carefully monitored, especially in terms of the safety of surface structures and rock mass stability. The article presents the concept of an analytic and graphic presentation of the results of the measurements of old workings, applying the Finite Element Method and ABAQUS software in model studies. The main purpose of such interpretation of the geodetic observations results is the application of methods providing wide possibilities to present the geometry of workings, their changes and the influence of the rock mass and surface.

Jan 1, 2008

By Kevin Sharman, Peri Mehling

A detailed assessment of acid rock drainage (ARD) potential was conducted at the Quintette Coal Mine site in northeastern British Columbia The site is unusual in that the coal seams contain low sulphur levels as compared to eastern coals (typically less than 0.5%), and the non-coal wastes generally do not to have the potential to generate acid on the basis of static ABA tests. The presence of small iron-stained seeps on the pit walls indicate localized sulphide oxidation, while the overall mine site drainage has remained of excellent quality with extremely low levels of metals after approximately 15 years of mining. Thus the site provides an excellent comparison to more problematic coal mine sites. For the Quintette assessment, static acid-base accounting (ABA) analyses of individual samples were compared to criteria for potentially acid generating materials developed for the U.S. Appalachian coal, as well as criteria developed in British Columbia for hard rock mines. Geologic units were characterized by the percentage of samples, or weighted thickness, that was deemed potentially acid generating (PAG). Links were then made to actual seepage and water quality emanating from geologic units around the site. Seeps at the site demonstrate a large range in pH (2.32 to 8.18). The few acidic seeps (pH < 4.0) were found to contain elevated levels of sulphates, dissolved iron, manganese and aluminum, consistent with the metals typically of concern in Appalachian coal mines. Other heavy metals that were detected in acidic seeps at Quintette included copper, zinc, nickel and cadmium. The use of simple ABA tests, and comparison of individual sample results with the Appalachian and British Columbia criteria, was found to be useful in predicting the probable sources of the small localized acidic seeps.

Jan 1, 2000

By Samuel B. Romberger

During the formation of most epithermal precious metal deposits geochemical changes can be characterized by the introduction of large amounts of silica, minor amounts of sulfur, and trace quantities of gold, silver, and other metals. During the same process, large amounts of alkalis and alkaline earth elements, such as sodium and calcium, and sometimes aluminum are removed from the rocks. In deposits hosted by carbonate sedimentary rocks large amounts of carbonate may be removed before or during the silicification process. Small amounts of iron may be introduced by the mineralizing solutions, however, in most epithermal deposits this may be a relatively immobile component and is locally derived. The results of these changes are deposits consisting of up to 90 to 95 percent silica as quartz veins, breccias, silicified host rocks, and jasperoids containing a few percent sulfides, mostly pyrite, and a few parts per million gold and silver. Other minerals commonly but not always present are barite, arsenic, antimony, or mercury sulfides, and tellurides. Often gold shows a spatial, and therefore an apparent genetic, relationship to pyrite in primary ores. Alteration and gangue assemblages sometimes include sericite and/or adularia, and parts of the deposits may contain alunite and/or clay minerals. Even though the value of these deposits usually lies in their gold content, silver is usually present in larger quantities than gold (Romberger, 1990). Based on these general characteristics observed in a large number of epithermal deposits, together with processes occurring in active geothermal areas to which they are often genetically linked (Henley, 1985), a model is proposed whereby deposition occurs along a subhorizontal zone separating environments of contrasting chemistries. The upper environment is characterized by oxygenated acid waters and the deeper environment by a reducing near neutral aqueous system. The model describes the chemical changes occurring as a result of mixing and/or boiling within this zone. It builds upon the physical models proposed by Romberger (1988a) for disseminated gold deposits and Bonham (1988; 1989) for volcanic rockhosted deposits.

Jan 1, 1990

By William C. Peters

"A large proportion of the earth&apos;s surface is blanketed by young sedimentary formations and by recent lava flows. How many Guanajuatos lie concealed beneath the rhyolitic capping of the Sierra Madre of Mexico? How many Kirkland Lakes are under the drift cover of the Canadian Shield? How many Wilunas are still hidden by the alluvium of the desert of Western Australia? How many ore deposits lurk underneath the basalt-covered plateaus of the Columbia River region? If erosion at Goldfield, Nevada, had stopped 100 feet higher, probably no ore would have been exposed. How many Goldfields are still awaiting discovery?" --Hugh Exton McKinstry, 1948

Jan 1, 1969

By Robert A. Metz

During the past decade we have witnessed spectacular improvements in productivity of open pit mining equipment. Thousand-horsepower engines, 200-ton trucks and 15-yard electric shovels, which such a short time ago were just dreams on a drawing board, are now realities. More productive equipment and metal shortages have encouraged increased production at existing mines and the development of new larger tonnage operations. Operators and engineers have been able to employ computers and various other types of automation to "stay on top of things". The mine geologist, however, is merely faced with a bigger and more rapidly changing pit to pick in. Keeping geologic information current in these mines presents entirely new problems to mine geological staffs. To obtain adequate geologic information on the developing orebody requires enlargement of the staff to share the work load or revision of methods in keeping with the times. The former has the disadvantage of loss of the comprehensive knowledge of the pit that a chief geologist likes to have, not to mention management&apos;s usual lack of enthusiasm for force increases.

Jan 1, 1970

By Bruce L. Bryson

In the past decade a principal growth area in refractory technology has been the development and use of extra high alumina refractories. The refractories user is asking for, and is prepared to pay for, higher purity, more dense materials with longer life, less maintenance, and better dimensional tolerance to meet the exacting demand of high output processes. High alumina and bauxite refractories are being used more and more to keep pace with the demand for guaranteed performance. The steel industry, for example, is starting to place great reliance on these products. A unique material now available with all the requirements for extreme purity and density is tabular alumina, already proving itself in many refractory applications.

Jan 1, 1973

By Michael Michaylov

INTRODUCTUCTICN The coal seams at Bobov dol basin are highly prone to spontaneous combustion in Bulgaria. The risks of endogenous fires (SPONCOM) exist mainly in gob area. During the last 15 years three different technologies for preventing and fighting SPONCOM have been applied in underground mines of this basin: pulp from hard material and water, foam and inerting with nitrogen. On the basis of experimental application of these technologies as well as theoretical and experimental research a new technology - Foam Pulp Technology (FPT) was worked out. It is very effective in difficult to reach places in a gob. BACKGROUND AND THE NEED OF FPT Application of the three methods mentioned above showed advantages as well as some disadvantages, allowing determination of their effective application scope depending on geological and working conditions. Their advantages can be summarized as follows: - Foaming: high viscosity at low density, which allows forming a thick layer; good surfactant wetting properties; excellent effective cooling during evaporation in high temperature zones. - Pulping with mixture of solid particles (e.g., fly ash) and water from surface installation: easy to apply in a mine; low operational and energy costs due to gravity transport from the surface to the gob: good ecological results because the waste material is returned back underground. - Inerting with nitrogen: volumetric action which doesn&apos;t restrict the thickness of treated coal pile; easy to apply in a mine; controllable nitrogen delivery depending on fire hazard conditions. Main disadvantages of the same three methods are: - Foaming: rapid disintegration due to intrusion into heterogeneous and porous media and high costs due to the need of frequent large volume foam flows (short foam&apos;s life); - Pulping: inapplicable for coal piles with high thickness which is of great importance in the cases of seams with ununiform hypsometry (rapid and frequent changes in a seam configuration) and/or great volumes of coal or ore piles particularly heated to a high temperature; strong dependence on gob floor declination; water draining of the working face area which impedes the movement of supports and chain conveyor&apos;s. - Inerting: relatively high costs hardly depending on the rate of face advance (fig.1) in comparison with the other methods; it is difficult to ensure sufficient oxygen at the exit end of the face. This problem is crucial in faces with a high level of methane emissions; accelerating of the oxidation and spontaneous heating of the pile after turning off the nitrogen supply. Inerting should be applied again at higher capacity of nitrogen supply (fig.2) and what is more important, it shouldn&apos;t be

Jan 1, 1995

By B. H. Kaye

Particle-size Distribution Specifications for Particulates. Feed to and finished products from size-reduction operations are defined in terms of the particulate sizes involved. It is also well to know whether the ultimate individual particle is being measured, or, if any aggregation or agglomeration of particles exists, whether this has been created by the size-reduction operation. The most complete description of a powder is given by its particle¬size distribution. This can be plotted in terms of cumulative percent oversize or undersize in relation to the diameters of particles, or it can be plotted as a distribution of the amounts present in each unit of diameter against the several diameters. It is common to employ a weight basis for percentage, but there are some data in the literature where frequency, or number of particles, is used. The basis of percent¬age, whether weight, frequency, or some less commonly used factor, should be specified, as also should be stated the diameter, its units, and preferably whether determined by sieve, settling velocity, or other¬wise. Fig. I presents two sets of distributions-ore cumulative and the other in unit intervals. The slopes of the 5-µ intervals of the cumulative curves are converted to percent per micron and plotted as a block, or histogram, from which smooth curves are derived. Powder A has a narrower, or tighter, size range for the bulk of its weight than powder B. Both materials have the same weights below and above the size marked by the arrow. Simpler treatments of distribution are possible. In some cases the significant value is the top size. Since the 100% point is dubious, some amount, as 95 or 98%, so specified, can be called top size. In other cases the percent on some sieve helps define coarseness. Merely stating that all, or all but a small percentage, passes a given sieve is inadequate for defining the true fineness or a material. Complete parti¬cle-size analysis to show the distribution is essential for most compari¬sons and calculations. Particle-Size Equations. A number of equations have been pro¬posed to correlate the quantity of a particulate material with its parti¬cle size to obtain a distribution relationship. &apos;s 19 In the literature it is often assumed that a powder must follow some distribution, such as the Rosin-Rammler-Bennett:20, 21

Jan 1, 1985

By J. Loredo

Asturias, in northern Spain, emits 18 Mt CO2/year to the atmosphere, which supposes the biggest industrial CO2 emissions in the country. In order to avoid CO2 emissions to the atmosphere, keeping the availability of energy from fossil fuels, background studies focussed to the selection of favourable sites for CO2 geological storage are necessary. In Asturias, the options for CO2 geological storage are sequestration in deep saline aquifers or sequestration in unexploted coal beds. In the area, there is the biggest coal basin of the country and a great Palaeozoic sedimentary basin with appropriate silicoclastic or carbonated reservoirs and impermeable caprock for CO2 geological storage, located in proximity to thermoelectric power plants and other sources of CO2 emissions. All evidences suggest that CO2 storage in deep aquifers is the most interesting option but a legal planning and a technical regulation are still to be done. The possibility for CO2 sequestration in coal beds is modest and associated to the CBM commercial exploitation. It is necessary to have in mind that the feasibility of CO2 geological storage in Asturias apart of technical factors will depend on price of CO2 ton, legal conditioning and possibility to apply emission rights to projects.

Jan 1, 2006

By Michael J. Martinson

Mine ventilation has been evolving as a separate field of study since the middle of the nineteenth century, and some practitioners might assert that mine ventilation has come of age as a discrete field in the last decade or two. Certainly the extensive literature now available on many facets of the subject, international congresses, the phenomenal upsurge of interest in mine ventilation in the United States of America since the passage of the 1969 Federal Coal Mine Health and Safety Act, and the existence of a virile mine ventilation society in South Africa with its own monthly journal all point in this general direction; on the other hand the lack of a rational design philosophy for ventilating mines suggests that mine ventilation may still be on the threshold of maturity. To generalise, many mines are still ventilated simply to comply with arbitrary statutory regulations, or with some ill- defined notion of reducing the risk of injury associated with the atmospheric environment in mines. Hazards in this category include oxygen deficiency, toxic gases and particulates, pathogenic gases and aerosols, explosive gases and dusts, and extreme climatic conditions. Although many mines are ventilated to abate the risk of a specific injury, there is inevitably a spectrum of latent and patent atmospheric hazards in every underground mine. The writer (Martinson, 1976) has previously drawn attention to the dearth of material on mine ventilation design in textbooks and technical journals, and to the overly simplistic approach sometimes adopted in the limited work published on the subject. The available material undoubtedly contains useful technical data and persuasive views, but seemingly could not be used to demonstrate the rational engineering approach to mine ventilation design advocated in the present paper. The range of papers presented at the 1975 and 1979 Congresses, and the diverse interests and affiliations of delegates, emphasize the multidisciplinary nature of mine ventilation. Easily recognisable topics include: Fluid mechanics Thermodynamics Heat transfer Flames and combustion Aerosol physics Radiation physics Geophysics and geomechanics Occupational diseases Epidemiology Industrial physiology Despite these heterogeneous connections there can be little doubt that mine ventilation is fundamentally an engineering field and not an off-shoot of some other branch of applied science. The distinction is important because mine ventilation has essentially developed as a form of ad hoc trouble- shooting, and in the process mining engineers have relied extensively on the assistance of experts drawn from other fields. Thus historically there has been limited scope for the application of rational design techniques, and personnel enlisted from scientific disciplines may not have had any previous experience in the intricacies of engineering design.

Jan 1, 1980

By Edward H. Eisenbrey

This paper is primarily concerned with the exploration for massive sulphide orebodies. In a discussion of this type, it seems appropriate to establish a few definitions so that all parties may consider the same beast and its habitat. First, the term "massive sulphides", as used here, not only denotes a body of mineralized rock containing in excess of 50% sulphides by volume, but a mass of sulphides that respond as a conductor to the electromagnetic (EM) systems currently in use in exploration. "Disseminated sulphides" refer to all of those sulphide occurrences that respond to the Induced Polarization (IP) geophysical methods most commonly in use in porphyry copper exploration. This latter definition may also include the disseminated sulphide halos so frequently found associated with massive mineralization as well as banded and stringer sulphide mineralization. It is plain to see that these two end members of our definitions can easily blend into each other. The term "volcanogenic" refers here to any and all geologic processes that have their origin in volcanic activity. Thus we are concerned here with the exploration for massive sulphide ore deposits derived from and affected by contemporaneous and post mineral volcanic activity. Furthermore, most massive sulphide deposits are apparently formed in a submarine environment, deposited with extrusive rocks and sediments and/or chemical hot spring accumulations, then enclosed and protected by the addition of more volcanic and sedimentary material then, probably folded and deformed into one of their myriad of shapes.

Jan 1, 1973

By D. J. Dunn

Grinding balls, simple in shape, are actually sophisticated machine components, and essential elements of mineral grinding mills. Their physical properties and quality must be adequate to achieve design life and grinding mission with few failures. Consistant properties and freedom from breakage are essential. Size, mass, hardness profile, chemistry, and microstructure are important variables which should be designed, specified, controlled, and verified to achieve optimal mill performance. Failure to specify ball properties in detail or failure to obtain required ball properties and quality can cause milling productivity losses and excessive costs that could endanger a milling operations survival in the competive mineral industry.

Jan 1, 1989

By William J. Shampine

The Floridan aquifer, which underlies all of Florida, yields water with a sulfate content of less than 50 parts per million in the north-western part and throughout most of the center of the State. In the southern part of Florida and along the most of the east coast, the sulfate concentration generally exceeds 100 parts per million and is as much as 1,700 parts per million. The sulfate concentration tends to be higher in the deeper zones of the aquifer. This map shows the sulfate concentration in the upper part of the aquifer. Sulfate is found in almost all natural water. Sulfate in rainwater is dissolved from impurities and gases in the atmosphere. Rankama and Sahama (1955, p. 314) report that the average sulfate content of rainwater is two parts per million; however, concentrations have been as high as 283 parts per million. Much of the sulfate in rainwater comes from hydrogen sulfide gas which is generated in shallow water on the continental shelves. The combustion of bituminous coal used for heating and industrial purposes seems to be an important local source of sulfate.

Jan 1, 1966

By Christopher Haycocks

Self-supporting, open stoping underground mining methods are some of the earliest, starting with the prehistoric flint mines of Europe and the Egyptian gold mines of Nubia in the time of the pharaohs. When the early miner created an opening, it had to be inherently stable and self-supporting to enable him to continue. Therefore, as mining progressed beyond simple gophering, self-supported open stoping methods were devised to meet the needs of individual ore bodies. Timber for support appears in mines as early as 1000 BC, but this was for no more than local ground control. The ingenuity of mining engineers through history has so refined open stoping methods that today they produce more tonnage than any other mining system. Self-supported open stoping finds its application in moderate to strong rocks that exhibit little jointing or fiagmentation. Good back, hanging wall, and footwall conditions that require no more than incidental support are an essential part of these mining methods. Open stoping methods find applications in all inclinations of ore body from flat to vertical, and where ore movement may be either mechanical or under the influence of gravity. Table 18.0.1 demonstrates the range of ore bodies suitable for open stoping, with particular reference to their dip and the deposit thickness. Most of the flat-dipping applications use ore pillars for overall support and ground control that may be recovered under some conditions after completion of normal stoping practices. In steeper ore bodies, rib, crown, and sill pillars used to block out the ore may be recovered subsequent to the completion of stoping. Open stopes are frequently filled to facilitate pillar recovery. Two of the methods, vertical crater retreat (VCR) and shrinkage stoping, utilize fragmented ore for temporary support in the stopes. In these two cases, the stope is not strictly open until after drawdown.

Jan 1, 2008

By Larry Murphy, Mohammad R. Jafari, David M. Giel, Sharat K. Kalluri

"Built in 1940’s to provide a key roadway arterial between New York and Boston, the Heroes Tunnel is the only highway rock tunnel in the state of Connecticut and is part of the Wilbur Cross Parkway. This 365.0 m long tunnel consists of two barrels, each with two lanes of traffic, and carries over 71,000 vehicles per day. For nearly 70 years, the tunnel has seen millions of vehicles pass through but time has taken its toll and now the tunnel lining, ventilation system and radial section joints are significantly deteriorated and in need of rehabilitation. Owned and maintained by the Connecticut Department of Transportation (CTDOT), CTDOT initiated a unique managed approach to mitigate the risk, social impacts and financial implications associated with rehabilitation of this tunnel. This new approach consists of performing field inspection and conducting a comprehensive study to explore six rehabilitation options, including construction of new tunnels and enlarging the existing tunnels. The main criteria for this study are: Impact on traffic and the resulting delay cost; Construction cost; Construction duration; and Construction complexity. This paper will present the results of the alternative study. PROJECT BACKGROUND Location and Importance Heroes Tunnel is located in the State of Connecticut within the Town of Woodbridge and the City of New Haven near the Town of Hamden border. Heroes Tunnel is the only true highway tunnel in the State of Connecticut. The tunnel is part of the Wilbur Cross Parkway (Route 15), a scenic connection between Hartford and New York. Originally constructed and opened to traffic in 1949, the tunneled portion of the parkway passes through the West Rock Ridge. The tunnel was originally named West Rock Tunnel, but was re-designated as Heroes Tunnel in 2003. Route 15 is a vital roadway within the State transportation infrastructure. In the vicinity of Heroes Tunnel, Route 15 carries approximately 71,000 vehicles daily. Locally, Route 15 provides access to residences, shopping centers, and points of interest, as well as other state roadways. Regionally, Route 15 connects New York to the Hartford area and serves as an alternate expressway route to I-95 and I-91. The tunnel is approximately 365.0 m long and passes through the West Rock Ridge. West Rock Ridge is an 11.3 km long rock ridge located on the west side of New Haven. A network of suburban streets abuts the mountain on all sides and a seasonal paved park road climbs to the crest of the ridge. Figure 1 depicts the tunnel topography and location."

Jan 1, 2016