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By Robert B. Johnson

The refraction seismic method has been used as an indirect means of exploring for fluorspar in southern Illinois by the Illinois State Geological Survey. Use of the method has been restricted to those areas where mineralization is associated with faults, a restriction necessitated by the operating principles of the refraction method. The seismic data enable the interpreter to locate fault zones in the subsurface and, under ideal circumstances, to make estimates of dip direction and magnitude and vertical displacement provided the local stratigraphic units are known and are geophysically recognizable. In this instance, refraction seismic exploration has been successful in the surface mapping of well-developed faults, both simple and complex with which fluorspar may or may not be associated. However, less clear results have been obtained where faulting has been less severe and where there are numerous accompanying mineralized joints.

Jan 1, 1964

By M. R. Stauffer, Z. Hajnal

Seismic velocity determinations over Precambrian outcrops near Flin Flon, Manitoba, indicate that several different rock types have sufficient velocity contrast to make reflection mapping possible. Stratigraphic and fault contacts between metasedimentary and metavolcanic rocks have been mapped at some depth. A mu1ti-fold reflection survey attempted to trace the depth extension of an ore-bearing (Pb-Zn) rhyolite horizon within the metavolcanic rocks. A synthetic seismogram has been produced from a 10,000-ft sonic log and provides means of comparing seismic records with the local geology. From this the optimum frequency spectrum and the maximum resolution of the seismic signals were estimated.

Jan 1, 1978

By K. C. Ko, M. K. McCarter

Experimentation with seismic velocity measurements at Kennecott Copper Corp.'s Bingham mine disclosed that some recognized slide areas are characterized by low velocity profiles. A new traverse technique employed during the investigation allows rapid and precise measurements of a quantity referred to as "apparent velocity." This value is a weighted average of the actual velocity in the overbreak zone near the surface and in the intact rock at depth. The low points on the velocity profile are apparently the result of lower actual velocities and deeper overbreak in less competent material within the slide zones. Experience verifies the usefulness and practicality of the technique in delineating adverse areas prior to detectable failure. The technique may be employed as a rapid and economic means of slope stability surveillance in large open pit mines.

Jan 1, 1973

By Richard H. Sibson

Changes in seismic style along the San Andreas fault system appear to correlate with strike-parallel variations in regional heat flow. Large earthquake ruptures are associated with colder segments of the fault zone, while comparatively high levels of microearthquake activity and small to moderate shocks occur along the hotter segments, often in association with aseismic creep. Such behavior is consistent with geotherm and strain rate dependent profiles of shear resistance versus depth, constructed for quartz-bearing rocks. These profiles suggest that the transition from frictional to quasi-plastic behavior with depth should increase by a few kilometers passing from the hotter to the colder portions of the fault zone, giving rise to long-wavelength concentrations of distortional strain energy near the base of the seismogenic zone in the cold segments. Some support for this hypothesis comes from the observed deepening of microseismic activity passing northwest and southeast from the central Californian active region to the currently locked, ~400 Ian segments of the San Andreas fault that ruptured in 1906 and 1857.

Jan 1, 1982

By Cleland N. Conwell

APPLICATION of seismic methods to the location of buried channels in placer mining is fairly common knowledge, yet some of the facets of seismic refraction surveys have remained obscure in their application to mining. This description by a member of the U. S. Bureau of Reclamation team investigating bedrock at the Oso Dam site, may offer a lead to wider application of the method for bedrock determinations in engineering of mine and mill plants, tailing disposal, and water supply. It may also offer assistance in planning geological exploration in areas covered by overburden. Pertinent, and perhaps more than passingly significant, is that the seismic survey of the Oso dam site started at noon and was completed the afternoon of the next day. Location Oso dam site is on the Navajo River, Archuleta, County, Colo., 30 miles southeast of Pagosa Springs, Colo., 10 miles northwest of Chama, N. M. Bedrock at the proposed dam site is Mesa Verde Formation, Cretaceous age sandstone. The nearest good sandstone exposure is about 5/8 of a mile upstream from the location of the seismic determinations. The material above bedrock is sand and gravel with sandy loam soil covering benches above the river. The site appeared favorable, after a geologic and topographic reconnaissance, but overburden thickness was unknown. Exploratory drilling was not contemplated in the near future so a short seismic investigation was selected as the most suitable method of determining depth to bedrock. Field Procedure Geophysically, a seismic depth investigation is simply the measurement of depth from ground surface to the top of a layer which transmits seismic waves at a higher velocity. In this case the high-velocity seismic layer tentatively correlates with the Mesa Verde sandstone. Field procedure required a seismic explorationline or "spread" with 12 geophones set at measured intervals. Explosive charges were buried at few feet in the ground and detonated at shotpoints near the ends of the spread, and at intermediate points. The time of travel of the seismic waves from the shotpoints through the ground to each of the geophones along the spread was measured and recorded photographically with equipment housed in a field truck. The seismograph on each spread provided a time-travel graph. From it were computed the speed of seismic waves in various layers below the surface and depth to each different seismic layer below the shotpoint. In the case of the Oso dam site it was possible, in addition, to determine the depths below certain geophones, because there were only two seismic layers involved. Interpretation In seismic exploration waves are refracted from the top of layers which often correspond to divisions between subsurface formations. When drill holes are available the geologic logs offer a means of correlating stratigraphic breaks with seismic layers, improving reliability of seismic interpretation in terms of depth to bedrock or other geologic terms. There were no drill holes available in the case of the work at the Oso dam site. Geologic conditions appeared favorable for seismic technique because of excellent contrast in seismic wave velocity between the overburden and the Mesa Verde formation. The upper layer had a velocity of approximately 2500 fps and was interpreted as overburden, the lower layer had a velocity of approximately 9000 fps and was assumed to be the sandstone. These velocities are of the order expected in these materials. The seismographs obtained at the Oso dam site were excellent. The energy from the shot came in strongly at each geophone, giving an easily read record. Time-travel graphs plotted from wave arrival times were uniform and made interpretation comparatively easy. In Spreads 1 and 2 near the river the lower velocity layer was 12 to 15 ft deep. For the spreads on higher ground, or the bench south of the river, it was from 15 to 29 ft deep.

Jan 1, 1952

By William E. Bonini, Eugene A. Hickok

IN the course of an investigation directed toward expanding ground-water facilities in Essex and Morris counties, New Jersey, the Board of Water Commissioners of the city of East Orange authorized a seismic-refraction survey1 for the purpose of delineating bedrock topography below unconsolidated overburden. Results of the survey were highly satisfactory and led to the preparation of a comparatively detailed bedrock contour map. Knowledge of the bedrock depth and configuration was an important aid in selection of sites for test drilling. The portion of the East Orange Water Reserve under consideration is in the flood plain of the Passaic River about 10 miles west of Newark, N. J. The flood plain is about 175 ft above mean sea level and is bordered by low hills rising to elevations of approximately 250 ft. The bedrock underlying the Water Reserve consists of sandstone and shale of the Triassic Brunswick formation and is covered everywhere by deposits of unconsolidated glacial outwash sand and gravel, lacustrine clay, and recent river silt as much as 150 ft thick. Yield of wells in the sandstone and shale averages 100 to 200 gpm. Since production wells constructed in the sand and gravel aquifer in the buried river valley shown on the contour map (Fig. 1) yield 300 to 1400 gpm, it was proposed to locate additional production wells in this buried valley, where the yields per well would be maximum.

Jan 4, 1958

By Walter A. English

CONTENTS PAGE Introduction. By WALTER A. ENGLISH 1 Theory of Seismic Reflection Prospecting. By WILLARD H. TRACY 2 Instruments for Reflection Seismograph Prospecting. By ARTHUR NOMANN 9 Seismograph Field Operations. By FRANK ITTNER 15 Determining Geologic Structure from Seismograph Records. By P. C. KELLY 22 INTRODUCTION BY WALTER A. ENGLISH,* MEMBER A.I.M.E. THE four papers making up this symposum have been prepared espe-cially for those who have no knowledge of seismograph prospecting. To many people mathematics is a formidable subject, and many are discouraged from studying seismograph prospecting under the mistaken assumption that the mathematical requirements are severe. In the papers presented here there is not a single mathematical equation. We believe that considerable competence in dealing with some of the most important problems of this work can be attained without any mathe-matical training whatever. At the present time, there is a real need for interpretation of results by persons thoroughly competent to bring geologic experience and imagination to bear on data that are subject to multiple interpretation from a strictly physical viewpoint. Likewise, those charged with the responsibility of planning seismo-graph exploration campaigns would do well to become familiar with as . much as possible of the technical aspects of the work. They would then be in better position to judge of its success in individual cases. It has often been said that the seismograph is a new structure-finding tool for the geologists to use. Using a tool and using its product are two different things. One does not use an automatic screw-threading machine when he buys a box of screws at the hardware store. Neither does the geologist

Jan 1, 1939

By Walter English

THE four papers making up this symposum have been prepared espe-cially for those who have no knowledge of seismograph prospecting. To many people mathematics is a formidable subject, and many are discouraged from studying seismograph prospecting under the mistaken assumption that the mathematical requirements are severe. In the papers presented here there is not a single mathematical equation. We believe that considerable competence in dealing with some of the most important problems of this work can be attained without any mathe-matical training whatever. At the present time, there is a real need for interpretation of results by persons thoroughly competent to bring geologic experience and imagination to bear on data that are subject to multiple interpretation from a strictly physical viewpoint. Likewise, those charged with the responsibility of planning seismo-graph exploration campaigns would do well to become familiar with as much as possible of the technical aspects of the work. They would then be in better position to judge of its success in individual cases. It has often been said that the seismograph is a new structure-finding tool for the geologists to use. Using a tool and using its product are two different things. One does not use an automatic screw-threading machine when he buys a box of screws at the hardware store. Neither does the geologist

Jan 1, 1939

Seismological Society of America, University of California, Berkeley, Calif. Perry Byerly, Secretary. The Bulletin of the Seismological Society of America is issued quarterly. The four numbers each year are collected in a volume; in 1932 the 22nd annual volume was published. The articles contained in the copies of the Bulletin are not, perhaps, of direct interest to a mining engineer but many of them will interest geologists. To indicate the type of articles contained in the Bulletin, the following titles, taken from the current issue, for June, 1932, are given: The Japanese earthquake of march 28, 1925, and the Problem of depth of focus; the earthquake in Santa Monica Bay, California, on August 30, 1930; a new vertical seismography. For copies of the bulletin or information concerning them, address the above.

Jan 1, 1933

By F. R. Morral

INDUSTRY has yet to find a universal solution to the problem of engineer personnel selection. Today, the choice of the right man for the right job is even more pressing than ever before. The age of the hard apprenticeship seems to have passed. In its place one finds the interviewer who must determine through personal contact and evaluation of college grades whether a graduate engineer will fit into his company's scheme. The problem, as it is constituted today, may be broken into four parts: Need for better use of human resources (there is a shortage of engineers, scientists, and skilled workers), productivity with higher efficiency, encouragement of personal pride in work performed, and employee's happiness on the job and away from it.

Jan 4, 1953

By Dr. O’Neil Thomas J., Donald W. Gentry

"There is nothing so disastrous as a rational investment policy in an irrational world. " John Maynard Keynes INTRODUCTION The principles of time value of money concepts were discussed and illustrated in Chapter 3. The importance of time value of money and the role it plays in the discipline of engineering economy have been well established. Chapter 9 further illustrates that project evaluation criteria that fail to consider this aspect are seriously deficient in providing appropriate capital budgeting decisions. Obviously future project receipts and expenditures must be discounted to permit valid comparisons with current cash flows. Although the concept of discounting is widely accepted, the selection of the appropriate discount rate has been the source of considerable debate and much disagreement. This chapter, then, provides an overview of the theoretical and practical considerations for determining or calculating the appropriate rate for discounting, the corporate cost of capital. Note specifically that the assumption of constant business risk among the various investment alternatives is maintained throughout this chapter. THE INTUITIVE APPROACH The fact that interest exists suggests that all money has a cost associated with its use. The cost of this money may be the result of either explicit or implicit charges or some combination of the two. Any time an individual or a firm consumes less than the total earnings generated in a given time period that individual or corporation has either consciously or unconsciously decided to "invest" these excess funds in some type of activity. For instance, the individual or corporation may decide to invest the excess funds in tangible property, place the funds in a money market account, or simply keep these funds in cash. In any case, these funds have been invested in some type of activity which promises the investor some return on the invested capital. Remembering that the firm's primary objective should be the maximization of shareholder wealth, then intuitively it seems reasonable to suggest that the firm should not invest in any project where the anticipated return does not exceed the cost of funds (capital) committed to the project. Indeed, if the firm always invests in projects having returns in excess of the cost of capital committed to them, then the wealth of the firm (as measured by the price of common stock) should be in-

Jan 1, 1984

By R. W. D. Clarke, J. C. Folinsbee

INTRODUCTION This paper deals with a procedure for planning the mining of an orebody for which cross-sections, plans, grade of ore, and a geological estimate of the ore reserve have been prepared. The procedure begins with the preliminary selection of a mining method or methods on which an engineering evaluation will be carried out. The engineering evaluation is described in three parts: Conceptual Studies Engineering Studies Detailed Design An overall planning model is presented, plus an expanded model for the Engineering Study Throughout the discussion of the planning procedure, reference is made to three bulk mining methods, including block caving, sublevel caving, and longhole sublevel stoping, including a summary of the main characteristics of each of these mining methods. The planning model is designed for a longhole sublevel stoping method, but with modification, will apply to other methods. PRELIMINARY SELECTION OF A MINING METHOD To experienced mining engineers, identification of the nominal mining method for a given orebody normally involves a large measure of judgement. The geological data is reviewed to determine the configuration of the orebody, including size, shape, dip, grade, and metal distribution. Geotechnical data is considered, including the competence of the ore and host rock, faults, fracture patterns, groundwater, and the potential for in situ stresses. Geographical data, including the natural and societal conditions, are evaluated for their effect upon the mining method, and finally, economic data, basically defined as the value of the ore in the ground, but more specifically, including grade of mineable ore, distribution of ore grade throughout the orebody, and metallurgical recovery, will have a bearing on the nominal method selected. Preliminary evaluation of these factors will result in the elimination of the obviously inappropriate mining methods, leaving some method or methods for further, more detailed study. Since ore does not occur in simple geometric shapes, the method selected for more detailed study will require some variation to the standard. A few key factors will bear heavily on the selection and provide a basis for the most realistic choice. Geological Data The configuration of an orebody defined by the horizontal and vertical dimensions, the dip and strike, and the possibility of repetitive occurrences will have the major influence on the selection of the mining method. For bulk mining methods, the dip of the orebody should be steep, or the orebody must be thick so that gravity can be utilized to deliver fragmented ore to a central gathering area. Geotechnical Data The geotechnical data will be studied in greater detail when the nominal mining method has been selected and the engineering evaluation is undertaken. However, some basic initial information must be available. The structural strength of the ore and host rock, including the effect on it of faulting, fracturing, and insitu stresses, must be known. Data from exploration drilling and examination of drill core will assist in the preliminary assessment of these factors. Highly fractured ground may suggest a caving method of mining for certain orebody configurations, whereas highly competent or strong ore might indicate that for a similar configuration, longhole sublevel stoping will more likely succeed. Data obtained on groundwater from exploration drilling will be considered to determine if it can be controlled, or if it will represent a long term major expense or a hazard for which no control is possible.

Jan 1, 1981

By William N. Matheson

The major consideration in any management and engineering decision is the economic evaluation of factors. The right decision is the best cost decision, provided of course that it is the safest. Changes, improvements, and advances in mining technology, as in any business, come about through the pressure of economics in combination with the inventiveness and engineering abilities of efficient mine operators. Without proper economic evaluation and an appreciation of profit and loss of an operation, advances in mining methods would come about at a slow pace, if at all.

Jan 4, 1959

By C. A. Rowland, M. D. Flavel

There are seven basic comminution circuits that can be used to prepare beneficiation feed from the product of a primary crusher. This paper gives a comparison of these circuits based on average process and economical data. The paper is principally devoted to a discussion of the test work required to obtain the process data needed to evaluate each circuit. The results of the test work in conjunction with geographic and economic factors can be used to narrow down the choice of possible circuits to one, two, or three before making a detailed engineering study.

Jan 1, 1985

THE problem of picking the best students for an engineering college can no longer, be considered as simply one of determining the amount of general ability, but rather of finding special aptitudes for scientific work, according to Carl C. Brigham~ a Princeton University professor, who has been conducting researches on methods of selecting engineering undergraduates at Cooper Union, an evening school in New York City. When we first began this investigation seven years ago," says Dr. Brigham, "we thought the whole job would be done a soon as we had found a good method of measuring general intelligence. Today we feel that we are still about five years away from a solution, but on somewhat firmer footing than when we were looking for general ability.

Jan 1, 1928

Jan 7, 1951

By M. D. Flavel

The paper describes the physical aspects of the compression and impact crusher types along with the information needed to apply, install and operate them to best achieve designed performance levels. It reviews key performance parameters such as energy size relationships for crushing processes and how automation devices can optimize machine productivity. Weaknesses of existing application engineering methods are discussed. The use of pilot plant information and appropriate laboratory testing procedures are reviewed from the point of view of the application design engineer so that the best type of machine can be selected for a proposed installation.

Jan 1, 1982

By R. W. Schenker

INTRODUCTION Environmental and occupational safety and health requirements often have a major impact on the design of comminution circuits, leading to increased capital and operating costs and reduced income. A project's capital cost can be increased by environmental permitting delays and the addition of dust collection equipment. Income can be reduced by lost production during unscheduled plant shutdowns for dust collection equipment maintenance. Dust collection equipment must be carefully selected and sized to minimize impact on the project. The equipment performance must comply with environmental regulations and allow working areas to comply with occupational safety and health regulations. Unnecessary overdesign could jeopardize the project's desirability from an economic standpoint. The equipment must be sufficiently reliable to avoid interference with production schedules. This chapter provides practical information on the selection and sizing of comminution circuit dust collection equipment that is consistent with the requirements stated above. It presents information on the reasons and general principles of dust collection; various types of dust collection equipment; and design criteria for ventilation hoods, duct systems, fabric filter dust collectors, and fans. An example discussing the selection and sizing of dust collection equipment for a simple comminution circuit is also presented. REASONS FOR DUST COLLECTION Dust collection equipment should be installed in comminution circuits for a variety of reasons, some of which are discussed below. These include compliance with government regulations, minimization of housekeeping requirements, product recovery, and improvement in public and employee relations. Compliance with Government Regulations Dust emissions from comminution circuits must comply with both air pollution control and occupational safety and health regulations. The regulations that may influence the selection of comminution circuits are discussed in more detail in Chapter 2. Air pollution control regulations limit the emission of dust, as well as visible emissions to the atmosphere and the concentration of dust in the ambient air. These regulations minimize the degradation of air quality and impact to other environmental considerations such as the health of the general public,

Jan 1, 1982

By Andrew W. Jenike

STORAGE AND FLOW Introduction The layout and design of a bin or stockpile for bulk solids should assure reliable feed at the required time and rate without spillage and, when required, without segregation and degradation. The typical procedure in the design for gravity flow follows these steps: 1. The bulk solids to be stored are identified and the range of moisture content, temperature, feed rate and time of storage at rest, as well as the storage capacity, are specified. The materials of construction of the hopper, that is of the converging part of the bin, are decided upon. Hopper liners and coatings to reduce wall friction are considered. 2. The flow properties of the bulk solids and the friction angles against the wall materials are measured for the expected range of conditions. 3. The width of a slot outlet needed for reliable flow of each solid under the full range of conditions is determined from the tests. This dimension is an explicit measure of flowability of a solid. The widest slot determines the critical solid and the critical conditions. 4. A suitable feeder of size sufficient for the widest slot outlet is selected. 5. On the basis of the measured wall friction angles, a suitable wall material is selected and a mass flow hopper is designed to ensure reliable and uniform flow of solid into the feeder and to minimize the load on the feeder. The mass flow hopper may extend upward to the intersection with the cylinder thus producing a mass flow bin. Alternatively, the hopper may terminate at a height equal to a few widths of the outlet and then expand at a less steep slope in its upper part in order to save headroom, or it may terminate in the flat bottom of a bin or stockpile. The choice depends on the flow properties of the solids and the size of the bin or stockpile. 6. The design of the bin is completed for the specified storage capacity. Multiple hoppers and

Jan 1, 1982

By Robert B. Hill

A history of gravity classification shows the development of many types of equipment with several prominent types continuing in use today. Part of the development and evolution is the spiral classifier. Data will be presented showing characteristic size separations in a closed circuit grinding operation. Comparisons with hydro- cyclone operation will be shown including operating cost comparisons. Effects of variables will be shown in spiral classifier operation. Finally, other uses for spiral classifiers will be described.

Jan 1, 1982