Search Documents

By John R. Hawley

Ontario, one of the richest mining districts in the world, is a natural storehouse for much of the earth's fresh water supply. Covering over 344,000 square miles, the surface of this Canadian Province is dotted with 250,000 fresh water lakes and is laced with uncounted thousands of fresh water rivers and streams. The southern portion of the Province, for the most part, is flat or lazily rolling farmland. This is where most of the people in Ontario live. Although it is not a major mining area, southern Ontario does possess important deposits of salt, oil, gas and gypsum. Most of these deposits are being actively worked. Toronto, the capital city of Ontario, lies deep in the southern region. Here the climate is mild and the winters are short. The total annual precipitation consists of 27 inches of rain and 65 inches of snow. Most of the major mining companies that do business in Canada have made Toronto their Canadian headquarters. There are two reasons for this. The first, of course, is money. Toronto is the gathering place of many well- known financial institutions. The second is access. Toronto lies within a few hundred miles of some of the most spectacular mining enterprises that exist in the world.

Jan 1, 1973

By H. C. W. Bosman

"Over the past five years, contributions from geologists and mining engineers were instrumental in the successful development of MEPS. It is a system of FORTRAN programs specifically designed to be used by mining personnel to solve geological and mining problems. MEPS is a flexible keyword-driven system. Extensive error editing procedures significantly reduce the time required to proceed from problem recognition to solution. Possibly the most attractive feature of MEPS is that computer solutions may be guided or selectively modified to obtain desired solutions. Some highlights of MEPS are:1. Vocabulary that is familiar to mining people.2. Geological data storage and retrieval.3. Statistical analysis and variograms.4. Contour maps of assays and geological horizons.5. Trend surface analysis with residual evaluation.6. Ore reserve calculations.7. Open-pit mine design.8. Marginal profitability calculations on pit walls.9. Production scheduling.10. Vertical cross-section plots indicating pit outlines, ore grade contours and selected geological horizons."

Jan 1, 1973

By R. Zins

During the past few years, a completely new concept has been applied to the design of drives for operating at very low speeds. In this, the motor is supplied by a variable-frequency thyristor cyclo-converter. Today, frequency converters with practically unlimited power ratings can be constructed. The system frequency of 50 or 60 Hz is reduced to about 10 % of these values. This makes it possible to operate the synchronous motor, which has a correspondingly high number of poles, at the extremely low speed of the driven mill, i.e, without interposed gearing. The first motors of this type were built to drive ball mills in the cement industry, which are very similar to those employed for ore processing. Here, too, the tendency is to build units of ever increasing capacity. In the case of conventional drives with mechanical gearing, this involves correspondingly increasing difficulties. These difficulties have prompted various studies of the possibility of applying the new type of drive to ore mills as well, but a gearless drive has not yet been built for this application. However, gearless drives for ore mills will certainly materialize soon and it was therefore considered a logical step to report at the A.I.M.E. Conference on the experience gained with these drives in the cement industry, and on the present state of development.

Jan 1, 1973

By Theodore H. Eyde

In 1971, the Minerals Division of The Superior Oil Company acquired exploration rights to an unpatented claim group in the Superior (Pioneer), Arizona mining district, lying west of the Concentrator fault. This major post-mineral fault displaces the Magma vein-fault, which is mined in the Magma Mine at Superior, Arizona. The Magma vein-fault and the enclosing section of pre-mineral rocks consisting of Paleozoic and younger Precambrian sediments and diabase, is overlain by a thick section of post-mineral rocks, consisting of the Gila conglomerate, the Apache Leap dacite, and the Whitetail conglomerate. Geologic information on the thickness and attitudes of the rocks obtained from previous diamond drilling indicated that the section of post-mineral rocks might be from 3,000 to over 4,010 feet thick in the target area. (Figure 1) The Magma vein-fault is a steeply dipping vein which has produced nearly a billion dollars of copper, zinc, silver, and gold. It has been mined continuously for nearly 10,000 feet along the strike and nearly 5,000, feet vertically down the dip. It ranges from less than a foot to over 50 feet wide and contains sulfide mineralization con¬sisting of pyrite, chalcopyrite, bornite, and chalcocite.

Jan 1, 1973

By Gerhard Braüner

The report gives a review of the methods of predicting mine subsidence; these methods are used particularly in European coalfields. The methods are subdivided into two groups, based on mathematical expressions either for the trough profile or for the influence of infinitesimal extraction elements. The fundamental relationships common to all methods described herein are the principles of superposition and of equivalent extraction areas. The involved parameters are derived from field observations. For calculating horizontal displacements, their relation to the slope of the subsidence profile is applied. The time-dependent development of the subsidence process is characterized by the empirical "time factor." Modifications for the case of inclined strata are considered. A brief review of experimental and theoretical model investigations is given.

Jan 1, 1973

By C. A. Komar

Laboratory-scale hydraulic fracture tests were conducted by the Bureau of Mines on directionally oriented sandstone material, along with measurements of directional rock properties such as tensile strength, permeability, ultrasonic velocity, and dynamic elastic constants. In these tests, fracture orientation was determined as a function of various combinations of stress, rock saturation, rate of borehole pressurization, and direction of minimum tensile strength relative to minimum horizontal compressive stress. The objective of the experiment was to investigate whether horizontal stresses always controlled the orientation of induced vertical hydraulic fractures, or if under conditions of small differences in stress and/or slow borehole pressurization rates, the induced fracture direction was influenced by directional properties of the rock matrix. This study shows that the expected influence of horizontal earth stress on the orientation of an induced hydraulic fracture becomes negligible when¬ever the magnitude of the difference between the compressive stresses is 200 psi or less. When this occurs, fracture orientation is controlled by the directional properties of the rock--primarily permeability and tensile strength.

Jan 1, 1973

By Gerhard Braüner

The present knowledge on ground movements and mining damage is mainly based on observations made when mining seamlike deposits. The studies, rules, and regulations in different countries agree in that the differential ground movements, especially the strain, account for the damage to structures. Accordingly, large buildings are particularly susceptible. The opinions on what amount of ground deformation induces what degree of structural damage are not quite uniform. Mining damage can be reduced or prevented by structural and/or underground precautions. The latter comprise measures for generally reducing the ground movements (leaving pillars, filling, partial extraction) and for reducing temporary movements (rapid extraction, specially arranged workings). Because the differential movements decrease with increasing depth of mining, safety pillars are largely dispensable at greater depths. Shafts are mainly affected by the vertical derivatives of rock displacements, but extraction in the vicinity of shafts is feasible even under difficult conditions. The theoretical concept of the ground movement process established in part 1 of this work is in qualitative agreement with the facts herein observed. As a quantitative approach, it should be applied to calculating ground surface movements rather than rock movements about underground openings. It can be extended by introducing more detailed strata characteristics.

Jan 1, 1973

By W. G. Wahl

The Slave Province, a segment of Archean continental crust, migrated west and north from the northern flank of the Superior protoshield shortly after the Kenoran orogeny. The probable cause of migration, the path it followed and the cause of its coming to rest can be inferred from the Bouguer gravity data. The migration caused an indentation in the edge of the Superior protoshield which precluded the development of the Hudsonian orogenic front under Hudson Bay. As the nickel and asbestos deposits of the Thompson Nickel Belt and the New Quebec Nickel Belt are restricted to this orogenic front, no such deposits would occur under Hudson Bay.

Jan 1, 1973

By F. A. Campbell

This paper reports on mineral facies, ore textures, distribution of iron in sphalerites, and fractionation of sulfur isotopes in the Anvil ore body, Yukon Territory, Canada. Because the detailed structure and stratigraphy, both regional and local, are being studied by the geological staff at the mine and members of the Geological Survey of Canada, these topics will be discussed only briefly. The results of our study of the Anvil ore body have implications on theories of the genesis of ore deposits of this type, and these will be discussed. The Anvil ore body is the largest and most significant of three lead-zinc discoveries in an area of the central Yukon where major lead-zinc deposits were unknown only twenty years ago. The Vangorda deposit consisting of 22 million tons was discovered in 1953, followed in 1954 by the Swim Lakes deposit consisting of 10 million tons. The Anvil deposit, which consists of three ore zones, was discovered in 1964. The total reserve at Anvil mine is 63.5 million tons, with an average grade of 3.4% lead, 5.7% zinc, 0.16% copper and 1.2 ounces of silver per ton. This study is concerned primarily with the number one ore body which is about 2,400 feet long, up to 1,100 feet wide and 300 feet thick.

Jan 1, 1973

By James H. Harmon

As the trend to deeper mines, producing from marginal ore bodies, continues, mine hoists and their associated equipment will become more sophisticated, complex, large and expensive. Over the past two decades, mine hoisting equipment and systems have moved from steam engines to static rectification of ac to dc, and electronic controls are the standard. It is the intent of this section to present what is currently available in the field of mine hoisting equipment and systems. Because the present engineer has been exposed longer and more intensively to such things as computers, electronic devices, and machine design, no attempt has been made to make this a layman's article. Contributions from the electrical design and application engineer, gearing and hearing design engineers and other specialists have been incorporated. Some material will be devoted to electrical drive systems, rectifiers and gearing design among others. These items are inherent in the design of a mine hoisting system and the subsequent selection of the correct, most reliable and most economic system. The mine hoist can be a bottleneck between the underground mine and the surface mill. Correct selection of the right type of hoist is imperative. In this vital link between mine and mill, crude estimates of hoist capacity are not good enough, and the mining engineer must design and select the right hoisting system to meet the design specifications. 15.1-MINE HOIST TYPES There are two basic types of mine hoists available anywhere in the world today: the drum hoist on which the hoist rope is actually stored during the hoisting cycle, and the friction (Koepe), which merely passes the rope over the wheel during the hoisting process. Drum and friction hoists are "generic" terms which describe the two basic categories. Within each category are variations, as below. 15.1.1-DRUM HOISTS Drum hoists, as noted, actually store the hoist rope on the drum much the same as line on a fishing reel. To accomplish this task, the drums are so designed to store, in one or more layers, the footage of wire rope equal to the total maximum hoisting distance plus sufficient rope for cutting and inspection at regular intervals and for holding to the drum (see Fig. 15-1). Usual practice in hoist drum design is to allow three turns of hoist rope for holding on the drum and three turns for inspection cuttings. 1. Single-Drum Hoists-Fig. 15-2 shows a typical single-drum hoist as manufactured by most U.S. heavy-mining-equipment companies. With the exception of some very minor features, this design configuration is standard throughout the U.S.A. Fig. 15-3 is a plan view of a typical single-drum mine hoist. This particular hoist has a single-motor drive and a double-reduction set of gearing.

Jan 1, 1973

By A. J. Hargraves

"It is difficult to quantify comparatively the gassiness of a property. The most common index to gassiness, cubic feet of gas per ton of coal mined, is very arbitrary and does not take into account the geological setting nor the mining operation. The gassiness of a virgin coal in situ can be assessed, but no method is precise and the most accurate methods involve prolonged field and laboratory experiments. In general, gassiness increases with depth. Whereas 'gas' normally implies methane, other gases such as nitrogen, carbon dioxide, etc. may be present in seam gas also. The inflammability of methane is a problem, particularly the explosibility of a methane-air mixture; also oxygen dilution is involved in high gas concentrations and some gases are poisonous even in low concentrations. Cross measuring into a virgin seam is usually not as troublesome as development in the seam, where narrow openings may require strong ventilation to dilute gases exuding from the face and sides. Total extraction presents problems of gas from the working seam, or from adjacent seams, particularly at the return side, or of gas-laden air from the goaf streaming out or sometimes surging out intermittently, again on the return side. In pillar extraction or longwall retreating special roadways may be required to allow the side-to-side and end-to-end flushing of the goaf which is somewhat inherent in longwall advancing. Layering may occur, particularly where ventilation conditions are not brisk. Outbursts of gas from adjoining seams may be induced by sudden rupture of roof or floor in caving workings. Outbursts of coal and gas from the working seam may occur, mostly in development work, under special environmental circumstances. Gas problems may be reduced or eliminated by predrainage of gas ....:. rarely successful from the working seam - usually undertaken from adjoining seams prior to escape of gas released by caving. The ideal solution - general predrainage of gas to the surface from measures prior to mining - has yet to be accomplished. • In the planning of gassy mines it is possible to make an assessment of gas contained in the seams and to estimate what proportion will be released into the mine air, but emission of gas into mine workings is never steady and at present there is no better planning criterion than experience at the mine next door!"

Jan 1, 1973

By Roger G. Long

In May 1973, the Bureau of Mines asked Arthur D. Little, Inc. (A DL) to investigate existing industrial communication standards that may be applicable to the problem of developing standards for mine communication, considering that the standards that may ultimately be developed will require simple field procedures for the industry and the inspectorate to determine that communication systems are properly functioning. The emphasis on this study is on telephone communications as related to coal mine applications. B. TASKS The tasks agreed upon for this program were as follows: 1. "Investigate the current practices and existing standards of other industries under government regulation. 2. Determine applicable methods for industry personnel and inspectors to ascertain conformance on-site with minimal test hardware. 3. Review the Bureau's approval, testing and inspection procedure as it may impact the development of such standards. 4. From the above studies investigate the development of installation and performance standards for mine communications, including voice and telemetry. 5. Prepare a written report specifying what standards and field inspection techniques are applicable with recommendations for development of subsequent data and ultimately standards and field inspection techniques. 6. Prepare a written summary of the findings of various investigations with an appendix covering the detailed findings of each investigation. 7. Prepare a list of suggestions of additional assistance the Bureau might require in subsequent phases of developing communication standards and means of ascertaining performance."

Jan 1, 1973

This report, the second in an annual series, summarizes information on latest technological developments and advances, and identifies trends in mining and metallurgy based on a review of activities in the minerals industry in 1971. Exploration and mining data obtained from an annual canvass are presented for 1971 and are compared with similar data obtained over the past decade.

Jan 1, 1973

By Edward J. Budill

One of the most dramatic innovations in the materials handling industry has been the development of stacker cranes and automated material handling systems. The stacker crane with its many capabilities and the development of reliable industrial automation controls have combined to produce dramatic achievements in an area once characterized by inefficiency lack of management attention, and capital investment. In many areas of application however, stacker cranes and high rise storage systems have been designed and installed with insufficient thought given to their integration into the overall operations of the plant or distribution facility. This paper will look at some new and interesting breakthroughs in the integration of stacker cranes and high rise storage systems into the total manufacturing plant system. In this paper we will refer to both bridge type stacker cranes and aisle stackers. The bridge type stacker crane was developed first and was initially developed with forks or other handling devices hoisted up and down a rigid or telescopic mast. This mast system was suspended from a trolley mounted on an overhead crane bridge. Today, the primary application of the bridge type stacker is in warehousing systems for handling basic metal products such as coils, bars, sheets and plates. There is no question that the bridge type stacker has achieved notable results in storage and handling of these commodities. However, a new area for stacker crane application has been developing which in many cases over-shadows the accomplishments in the storage area. This is the application of the bridge stacker as an integral part of the manufacturing processes, or in other terms the production applications of stacker cranes. The stacker crane has a number of attributes which makes these applications very important. First, the crane bridge provides the stable platform for the mounting of machinery which can accommodate the hoisting and lateral movement of large capacity loads. Today stacker cranes are being built with capacities of up to 30 - 40 tons. The bridge cranes can easily accomplish accommodation Of these large tonnages. Secondly, the mast system provides a stable platform for the mounting of a wide variety of manipulating devices which can be used for the placement of material into manufacturing processes, the extraction of this material from these processes, and movement to other points in the process area. These attributes combined with excellent operator control and safety have led to development of the stacker crane as a production tool.

Jan 1, 1973

By K. D. Bulin

"An interesting brief history review of shovels as the primary excavating tool will permit the reader to see that immeasurable development and resources have preceded the shovel excavators which today are used extensively throughout the mining industry. With this as a background, the shovel manufacturer has the ability to utilize his resources best in those areas of shovel development in which the maximum benefits of increased reliability, performance and ease of maintenance will improve the operating rewards to the user of the equipment. The author explains the function of the shovel as a part of the material handling system. A detailed description of those areas of the shovel in which the most recent developments and major improvements have been implemented in the manufacture of the shovel excavator arc included."

Jan 1, 1973

By M. King Hubbert

"The present large-scale use of energy and power by the human species represents a unique event in the billions of years of geologic history. Furthermore, in magnitude, most of the development has occurred during the present century. In the United States, the peak in the rate of petroleum production occurred in 1970 and that for natural gas is imminent. The peak in the world production of crude oil is expected to occur at about the year 2000 and that for coal production at about 2150 or 2200. For other sources of energy and power, water power, geothermal power and tidal power are inadequate to replace power from fossil fuels. Nuclear power, based on the breeder reactor and utilizing lowgrade deposits of uranium and thorium, has a larger potential than the fossil fuels, but it also constitutes a large perpetual hazard. The largest source of energy available to the earth is solar radiation. This source has a life-expectancy of a geologic time scale, is nonpolluting and is larger in magnitude than any likely requirements by the human s pecies. In consequence of the large supplies of available energy, the period since 1800 has been one of an unprecedented exponential industrial growth. This also has been accompanied by a world-wide ecological disturbance, including that of the human population. It can easily be seen that such a period of growth must be ephemeral in character and, in fact, is now almost over. One aspect of this transition from a state of exponential growth to a state of nongrowth is the present alarm over an ""energy crisis."" Actually, the world's present problems are by no means unmanageable in terms of present biological and technological knowledge. The real crisis confronting us is, therefore, not an energy crisis but a cultural crisis. During the last two centuries, we have evalved what amounts to an exponential- growth culture, with institutions based on the premise of an indefinite continuation of exponential growth. One of the principal consequences of the cessation of exponential growth will be an inevitable revision of some of the tenets of that culture."

Jan 1, 1973

By L. A. Haas

Hydrogen sulfide was decomposed to elemental sulfur in an electrical discharge. With He, N., or Ar diluents, a threshold voltage between 1 and 3 kV was required for the decomposition reaction to occur in a laboratory ozonizer. Above the threshold voltage, the HAS decomposition rate increased with increasing voltage, but the increase was more pronounced with argon diluent than with either nitrogen or helium. In common with other reactions in an electrical discharge, the B2S decomposition decreased with increasing temperature in the range of -410 to +61° C. The reaction did not appear to be rate-controlled by a solid-gas sorption step because the introduction of activated charcoal into the electrical discharge zone did not significantly affect the decomposition yield. In the presence of polymeric chlorofluoro-carbon oil, 90 pct conversion of the 3 pct H2S in helium was obtained at 14 kV, 60 Hz, a 2-mm electrode gap, and a gas-residence time greater than 1 min. Under the same experimental conditions in the absence of oil, the conversion was only about 50 pct.

Jan 1, 1973

By Lewis. Clifford J.

The purpose of this article is to present design information and operating data on a pilot gas scrubber which is believed to be a new approach for removing noxious gases and particulate matter from the off gases of coal burning power plants and smelters. This principle of scrubbing gases, particularly, scrubbing with an aqueous slurry of lime, was conceived by the author early in 1972. The National Lime Association financed the design, fabrication and initial operation of the unit. The unit was fabricated by Hazen Research Inc. of Golden, Colorado. It has been tested on the off gases of two coal burning power plants and one smelter. The current environmental program has stimulated research and development activity directed toward the removal of sulfur oxides, oxides of nitrogen, particulate matter and other undesirable substances from gases discharged into the atmosphere. At present, most of this effort is focused on the removal of sulfur dioxide and particulate matter by aqueous scrubbing of the gases. This presentation deals particularly with the removal of sulfur dioxide using an aqueous slurry of lime as the scrubbing medium. In recent papers, the author has called attention to-the sludge problems resulting from aqueous scrubbing and to some earlier data on the pilot scrubber about to be discussed.1/

Jan 1, 1973

By Tapio Leskinen, Jouko Koskinen, Timo Nlltti, Lappalainen Seppo, Pentti Vanninen

"The Courier 300 on-stream analysis system manufactured by Outokumpu has now been in operation at five of the company's concentration plants long enough to give a reliable basis for closer examination of the benefits achieved in control of these processes. The first system was installed at the Pyhiisalmi mine at the end of 1967. Since November 1970, two analyzers have been in operation at Pyhiisalmi feeding the assay data to a process computer which controls the whole plant and does the optimization of the process. In October 1970 the Courier 300 analysis system was installed at S. T. O. LESKINEN J. KOSKINEN the Keretti concentrator of the Outokumpu mine, followed soon by installations at the Vihanti Mine in May 1971, at the new Vuonos mine in November J 971 and at t he Kotalahti mine in December 1971. Since installation of the Courier analysis systems, considerable improvements have been achieved in the control and the economy of the plants. Immediate knowledge of the changes in the process and the possibility for rapid action has resulted in evener production and higher capacity and recovery. The recovery has been increased most significantly at the Vihanti concentrator, which operates on a complex ore. Consumption of chemicals has been reduced at all concentrators. Due to the fact that process control and partly also bilance analysis are not achieved by conventional methods any more, it has been possible to reduce the personnel of the laboratories drastically. Two of the plants, viz. the Pyhiisalmi and the Vuonos concentrators, are computercontrolled. The Vuonos concentrator started operation in January 1972 under computer control from the very beginning. The Pyhiisalmi concentrator has been computer-controlled since 1970. The Courier 300 analysis system was described in detail at the AIME Centennial Annual Meeting (1971). In this paper, less attention is paid to the analysis system. Only the sampling system of the Courier 300 is described in more detail. In the development of sampling equipment, effective use has been made of the company's wide knowledge of the problems involved and the test field offered by its concentrators. The sampling equipment includes secondary samplers and six basically different types of primary samplers, with which most sampling situations can be managed."

Jan 1, 1973

By F. E. Armstrong

This Bureau of Mines publication reviews 237 papery on radiometric prospecting, which is the measurement of naturally occurring radioactivity in the earth's surface and its application to petroleum and natural gas exploration. Many theories and documented surveys are listed in both support and refutation of this reported phenomenon, and the Bureau of Mines is conducting research to obtain direct field information in order to determine the statistical credibility of a radiometric method of predicting petroleum accumulation.

Jan 1, 1973