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By G. W. Leney

Introduction and Historical Background The office and mining operations of Pacific Asbestos Corporation are located near Copperopolis, California in the foothills of the Sierras about fifty miles east of Stockton. This is historic country in the heart of the old Mother Lode gold district. Mark Twain's famous story of the jumping frog, written here, is still commemorated in an annual contest in Calaveras County,' and the camp at Poker Flats, described by Bret Harte, was only a few miles from the present mine.2 Joaquin Murrieta, the famous Mexican bandit started his three year reign of terror in this vicinity,3 and Black Bart, the P08 laureate of the stagecoach robbers, held up his first stage at Funk Hill, just three miles north of the mine. His last robbery was at almost the place, on the top of the hill overlooking the Stanislaus River ferry crossing. Although this was his favorite country, and he traveled extensively through it, he was not a credit to his acclaimed profession of Mining Engineer because there is no evidence that he ever recognized the asbestos, and he was finally caught as a consequence of the robbery at the ferry.4 One of the old stagecoach roads crossed the Stanislaus River at the mine site, and the ferry landing may still be seen from the main haul road into the pit. The road itself is partly buried under the rock dumps. In spite of its location and apparently prominent exposure, the first work on the asbestos deposit was not recorded until 1904.5 Development of the present operations was started in 1959 by Jefferson Lake Asbestos Corporation, a subsidiary of Jefferson Lake Sulphur Company. Management control of the company changed hands several times and it was later reorganized under the name of Pacific Asbestos Corporation. In December, 1968, a controlling interest was acquired by H. K. Porter Company, Inc. Figure (1) shows the mill and office buildings as seen from a site near the entry road. The offices are at the left with the mill warehouse in the foreground. The conveyor at left center carrys mine concentrates up the hill from the crusher. In the background are the dry rock storage building and mill tailings piles. Since the beginning of mining operations in 1962, seven and three-quarter million tons of ore and fifteen million tons of waste have been removed from the open pit which now measures about 1400 x 1800 feet at its widest points. The lowest operating level is at an elevation of 726 feet about 325 feet below the original surface. Figure (2) shows the open pit looking toward the west end. The main haul road can be seen along the side of the pit. A shovel is operating at the bottom of the pit while a front end loader on the level above provides ore for blending. In the background are rock dumps for waste stripping. The company markets an annual production of 30-35,000 tons of chrysotile fibre in groups 4 through 7, under the Mother Lode Brand

Jan 1, 1972

By W. J. Gibson

"This paper will provide a general assessment of the differences in construction and industrial labour relations. From this outline will come a detailed examination of labour relations in the construction industry and then specifically as related to the construction of mining projects, with emphasis on projects in isolated areas. Development of manpower forecasts, manpower availability, wage escalation formats, working rules, training and recruitment programs, and safety - as related to construction labour relations in the mining industry - are topics which will be dealt with."

Jan 1, 1972

By Kenneth K. Landes

So far my consulting in industrial minerals has been confined principally to carbonate rocks,-salt, coking coal, and glass sand. Much of this work has been for companies either too small for a full-time geological staff or unaware of the value of employing one or more qualified geologists permanently. It gave me considerable personal satisfaction to see several of the latter companies employ one or two full-time geologists after the completion of a consulting contract with them. One possible reason why some companies lack the wisdom to hire geologists is that they are dominated by engineers who still subscribe to the old idea that engineers are self-sufficient in all fields. They could have learned this from their professors. I once knew a Dean of Engineering who got purple in the face when a faculty committee was discussing the financing of a broad gauged engineering project and suggestions were made that assistance be obtained from the Schools of Business and Law and from some of the science departments tie pounded the table and shouted "Engineers are trained to handle all this!" In teaching engineering geology some years ago I used to tell the class repeatedly that the course would not make them geologists, that the purpose was to teach them

Jan 1, 1972

By Vard H. Johnson

"In contrast with the well-publicized Pittsburgh coal, and the Everglades of Florida, most coal-forming swamps of Cretaceous time in western North America occupied relatively limited areas. They formed in areas of irregular subsidence, bounded by the changing levee systems of meandering streams. Coke quality is determined by the physical and chemical behaviour of the vitrain during thermal decomposition. Vitrain is at least in part a colloidal substance, originally containing large proportions of water; its formation and survival depend on maintaining a shallow cover of stagnant water up to the time of burial. Heat from swamp fires or subaerial dyhydration could destroy it or impair its quality. Observed patterns suggest that the metamorphism is almost entirely thermal, and that there is little relation to tectonic stresses, or loading. These coals had probably achieved essentially their present rank prior to deformation. Evidence of frictional heating along the thrust planes is minimal or absent. Normally, coal beds are aquifers. Oxygen carried into the subsurface becomes available and reacts with the vitrain to destroy its natural thermoplastic properties. The tolerance of oxygen without loss of thermoplasticity is inversely related to the volatile content. Significant lateral variations of coal thickness are common and sometimes occur in short distances. In deformed areas these thickness changes are more commonly due to differential tectonic stress rather than to original thicknesses of coal. Locally, coal is known to have flowed into cavities, or fractures. These principals are discussed in relation to coal deposits of western Alberta and eastern British Columbia."

Jan 1, 1972

By W. Robert Power

Dimension stone includes a wide variety of natural materials that are put to an equally wide variety of uses. It is possible to classify dimension stone according to the end use to which the stone is put or according to the lithology of the stone. Both schemes are used by the United States Bureau of Mines in the annual Minerals Yearbook. The 1969 Yearbook lists 15 specific uses and has additional miscellaneous catagories. The same Yearbook lists five specific rock types or lithologies, and also includes a miscellaneous category. In a short presentation it would hardly be possible to list and define all these categories, much less discuss the evaluation of deposits with regard to all possible combinations. Besides, I am only slightly familiar with some of the uses and their requirements. I have therefore chosen to limit my remarks to some special problems in evaluating dimension stone that is to be cut and finished to specific sizes, tolerances, and finishes for use in buildings and some monuments. This use class is called cut stone in the Minerals Yearbook. In terms of dollar value it is the largest single use category. In 1969 the dollar value of cut stone was $29,122,000 which is more than twice the value of the next largest category. For those of you who are interested in other use applications of dimension stone I suggest that you start with recent articles by Bowles (1960), Currier (1960), and Barton (1968).

Jan 1, 1972

By Armine F. Banfield

The Purpose of the Paper It is fitting that the first paper of a session on the Financial Aspects of Mining should be on the basic data upon which any financial discussion of a mining project must be based. The history of a mining project starts with exploration in an area considered geologically favorable for mineralization and culminates in the discovery of a body of valuable mineral material commonly known as a mineral deposit. Subsequently more detailed exploration establishes the approximate size, shape, tonnage and average grade of the deposit by surface and/or underground drilling, -surface trenching and/or underground workings. Some preliminary metallurgical testing and other studies, as required, are made at this time. Development work is then carried out to provide representative samples for determining flowsheet and metallurgical balances, preparing the deposit for production and establishing more firmly the grade and mining characteristics of the deposit. A feasibility study is then made of the engineering aspects of the project including the estimation of operating coats, the capital required to place the deposit into production, profit and return on investment. A valuation of the deposit

Jan 1, 1972

By W. A. Hoyer

Neutron activation analysis for mineral identification has attracted the attention of numerous investigators, judging from the publications on this subject in the past few years. 1-9 The appealing aspect of this method of mineral analysis is its proven sensitivity in the laboratory. In principle, activation analysis is one of the few petro-physical methods whereby a direct analysis for a mineral itself is possible in a borehole. The successful application of activation analysis requires the use of particular neutron reactions, measurement of selected gamma-ray energy intervals, and optimum bombardment and detection times. For copper analysis, Labanov et al., 10,11 using a low-energy PuBe source, reported an acceptable logging means. On the other hand, Pradzynski12, in analyzing ores and process tailings, used high-energy neutrons and photons for surface measurements of process samples. The work of Labanov et al. was based on measuring the rate of decay of the activated copper and hence was not as definitive as might be desired. Equipment is commercially available to carry out activation studies in the field 13,14 Gamma-ray spectra can be successfully transmitted over ordinary logging cables and, with borehole high-energy neutron accelerators and lower-energy chemical neutron sources, a variety of neutron activation methods can be studied. The purpose of the study discussed in this paper was to determine the feasibility and practicability of logging for copper using neutron activation techniques and commercially available equipment. The laboratory study showed that Cu could be detected in rock samples in the laboratory by high-energy neutron activation of 63 Cu. In the field, however, due in part to the large volume irradiated, the direct detection of copper using high-energy neutrons was not as promising. Detection of copper by measuring both the direct gamma-ray emission and the excessively strong low-energy gamma-ray absorption appears promising. Copper was not detected either in the laboratory or

Jan 1, 1972

By James Douglas

For the past several years, inflation has placed increasing pressure on our economic system. The total effect of inflation is complex when combined with other factors which affect the economics of equipment. A mathematical model is described herein which can be programmed on a computer to determine the effect of inflation on economic life and profits after taxes. The computer output results in graphic plots which clearly show the relation of various percentages of inflation to life and profits. Inflation has become a common topic of conversation in the recent past. What is it and how can it be measured? What effect does increased inflation have on equipment policy? Research now in progress at the Construction Institute at Stanford University is beginning to unravel some of the mystery of inflation. As a start, let us answer the first question by defining the word inflation. The dictionary says that inflation is "an increase in the volume of money and credit relative to available goods resulting in a substantial and continuing rise in the general price level. It appears, in fact, that we are in an inflationary spiral which is "a continuous rise in prices that is sustained by the tendency of wage increases and cost increases to act on each other." 3 Inflation behaves just like compound interest. It takes more dollars of future years to buy an equal amount of a given commodity, be it a material or a service. Let us assume an annual inflation rate of 5 percent. Assume that 1Associate Professor of Civil Engineering, Stanford University, Stanford, California. 2Webster's Seventh New Collegiate Dictionary, Springfield, Mass., G. and C. Merriam Co., 1969. 3Ibid.

Jan 1, 1972

By I. R. Jonasson, R. W. Boyle

"Current interest in the distribution of mercury in the natural environment comes from quite different, though not unrelated, sources. Mercury has long been an important metal in many industries and has, therefore, been much sought after by mining interests. The presence of mercury traces in the various media of the natural environment, namely soil, rock, air, water and vegetation, is exploited by geochemists not only to find mercury and polymetallic ore deposits, but also to find most other types of economic metal mineralization. More recently, however, mercury has caught the attention of health authorities and environmental scientists who are becoming increasingly concerned over the hazards of mercury wastes and the danger these present to the environment and to man. It is now apparent that the trace quantities of mercury, considered so important and helpful to exploration geologists, can be concentrated in the biosphere to such levels as to present considerable problems for ecologists. This article summarizes most of the available data on mercury contents in materials of geological interest and presents average normal values for rocks, ores, minerals, soils, sediments, waters and plants. The geoch.emical cycle for mercury in nature is presented and the mechanisms of mercury migration around the cycle are discussed."

Jan 1, 1972

By John E. Caffrey

United States Steel Corporation began mining coal in southern West Virginia at the turn of the century, and until the late 40's production was confined to underground mines. Surface mining was initiated in our southern West Virginia -holdings as a means of recovering coal that could not be obtained by underground mining methods. After observing and evaluating surface mining methods employed by other companies, some of which operated on lands of U. S. Steel on a lease basis, we undertook the establishment of a surface mining operation. Our method, as, initiated in the early 50's, remains basically the same today. Variations have come about primarily by equipment modifications. The method consists' of a pioneer cut to establish the coal outcrop, a drill bench for drilling, blasting, and removal of the overburden from the top of the coal. The land is rugged except for the flood plains of some of the larger streams. The mountains have steep slopes, averaging 30 degrees, with relatively sharp ridges and very narrow valleys,. Geologically, the coals_ lie in the Pocahontas formation of the Pottsville group in the Pennsylvanian system. This means that the coals in our area of operation lie at the base of. The coal measures in the Appalachian range. The coal that we have mined is primarily the Pocahontas nos. 3 and 4 seams. We have mined negligible amounts of other seams in the Pocahontas groups above the no. 4 seam. The Pocahontas no. 3 seam, which is the lowest mineable seam geologically in this area, lies anywhere from 700 feet below: the valley floor up to 400 feet above the floor. This is occasioned by the Anticlinal formation which gives us grades Of about 9% at the anticline, decreasing to about 1 to 1-1/2% on the extreme flanks. We have the opportunity to engage in surface mining where the coal seams intercept the surface above the valley floors.

Jan 1, 1972

By R. B. Moffitt

INTRODUCTION In recent times the continuing depletion of high grade mineral deposits and the massive increase in raw material consumption have forced the metal mining industry to exploit ore bodies of lower and lower grades. To obtain a satisfactory financial return from these deposits, there has been the concurrent and evident trend towards increasing the size of operations to obtain benefits from the economies of scale. The evaluation, planning, and design of these large scale open-pit operations, so as to yield the maximum possible return on investment, is an extremely complex, iterative procedure. With profit margins trimmed, "small" errors can become much more significant and with exploration costs spiralling, accurate and rapid evaluation is essential. It demands a sophistication and precision in the evaluation process unheard of ten years ago. What follows attempts to describe the need to thoroughly plan the overall evaluation programme such that duplication of effort is avoided and all relevant information is systematically recorded from the outset of exploration. The final section of the paper takes a realistic case study to illustrate the significance of pit slope angles on the design of the final pit and the economics of the total project. THE EVALUATION PROGRAMME The team, (for a team effort it must be), that is charged with the responsibility of conducting the evaluation exercise, has the difficult task of placing values on a multitude of independent and inter-related variables. Each variable has some economic significance; the degree of significance varying according to the metal sought, the environment in which it occurs, the vagaries of the market place, to name but a few of the problems facing the project team. From this maze of variables, the team must identify those that have the most critical influence on the overall economics of the proposed venture. Investigations must then be set in motion to quantify these controlling factors more precisely. It is important to recognize that such investigations form part of the evaluation programme and require monitoring for both timing and cost as the whole exercise of evaluating the project continues. To add to the difficulties, the economic significance of any particular variable may change during the course of the programme.

Jan 1, 1972

By H. G. Stephenson, C. W. Gregory

"This article describes the methods used for pillar extraction in the Wilson Seam at Canmore Mines, Alberta. The Wilson Seam is extremely gassy and varies in thickness between 7 and 30 ft, with an average of 12 ft. The gradient varies from 5 to 30 degrees, with an average of 15 degrees. The seam was developed using Lee Norse miners to form pillars which the company intended to extract using the same machines. Before pillar extraction commenced, an abandoned and inaccessible mine 160 ft above the Wilson had to be drained of 360 million gallons of water. When this was done pillar extraction commenced. Conditions in the mine slowly deteriorated and after 6 months the decision to withdraw the continuous miners was taken. Slusher hoists were installed to replace the continuous miners, with the result that roof conditions and safety steadily improved."

Jan 1, 1972

By E. A. Wieselmann

This chapter presents a successful approach for achieving mine entry stability at the Cane Creek potash mine by the utilization of closure measurements. The mine is located in southeastern Utah (Fig. l). Mining is being conducted at depths in excess of 3000 ft under structurally complex geologic conditions typical of the Paradox salt basin. The closure measurement systems described have definite application for determining relative entry stability in other nonelastic rocks which are similar in behavior to potash. Similar types of closure measurements have been taken in various underground openings throughout the United States, Canada, arid Europe. Application of this closure data has previously met with varying degrees of success as a tool for design of under- ground openings in both elastic and nonelastic media.1-32 Closure measurements can be made easily and economically and they provide a practical solutiori to a practical problem. They are in-situ measurements which do not necessarily require laboratory correlation. Simple closure measurements have special significance in potash because "steady-state" ' closure rate, or creep, of the entries is measured. These closure rates can be utilized because nonelastic media such as potash will never achieve absolute stability around a mine entry. The potash will tend to creep or deform until all entries are closed and the overburden stress is redistributed over what was previously the mine area. The time for this ultimate effect to occur is dependent on a number of mining and geologic variables. Percentage of mine extraction, mining

Jan 1, 1972

By H. J. Lechtenberg

Preliminary results are given of solvent stimulation of two wells producing viscous oil (14°-17° API) from the Tar zone in the Wilmington field, California. The solvent (coker oil, an intermediate refinery product) was injected into the formation, and after a soak period, the well was returned to production. Data are given on crude oil properties, solvent properties, determination of volume of solvent in the produced oil, rate of oil production before and after stimulation, volume of additional oil produced, and volume of solvent recovered. Although further study and improvement of the method arcs needed, cyclic solvent stimulation appears to be an unqualified success in one well and a moderate success in the other.

Jan 1, 1972

By D. N. Madge

A description will be given of an approach to plant process automation based on the strategy of first developing an information system followed by later development of process models. The advantages of this approach over the unit process control will be outlined. Some insight will be given into the risks associated with this method. These risks can be shown to be primarily economic.' Some reference will be made to two Cominco installations in the interests of illustrating the generality of the information systems approach.

Jan 1, 1972

By C. P. Davenport

At the risk of belaboring certain facts which have so often been stated in the past, please bear with me while I set the stage. What are the projected electrical power needs of the nation and of the Northwest during the next 15 to 20 years? No one who has researched the subject over its historical past has reached a substantially different result than the following simple conclusion: electrical power requirements are doubling every decade. There are some who question the necessity of a power company's need to install capacity every ten years equal to what it has done during its entire previous history; there are even those who would argue that such growth should be arbitrarily curtailed. We are not here today to decide who should have light, heat, jobs and comfort, for we know that a power company must, by law, meet its responsibilities of providing the energy the public expects when the switch is thrown. The Northwest area (the States of Oregon and Washington), for which I speak, has the same case history of electrical power need as does the nation as a whole, and the requirement boils down to roughly an average of a million kilowatts of new capacity each year over the next ten years and we can estimate an average two million kilowatts per year in the 1980's. This is simple arithmetic, but the problems of meeting this exhausting schedule are a real challenge. The subject to which I address this paper is the role that Western Coal will play in the 6 billion dollar investment in these power generation stations. That 6 billion dollar figure represents today's dollar value and you may wish to apply your own escalation - frankly, I haven't the courage.

Jan 1, 1972

By V. M. Lepetic

Large tonnages of copper and molybdenum sulfide ore are treated by flotation. Substantial savings could be realized, particularly in high-capacity concentrators, by use of a simplified flotation technique involving lower reagent consumption. Chalcopyrite and molybdenite from some deposits can be floated by use of only a frother as a single flotation reagent; acceptable concentrate grade and recovery can be obtained. Separation of molybdenite from copper sulfides may become simpler and less costly. The genesis of the ore and the ions present in the flotation pulp liquid phase appear to be the major success-determining factors.

Jan 1, 1972

By Raymond Derzay

This publication is intended to be of value to the mineral industry in establishing and maintaining effective programs for preventing noise-induced hearing loss. Factors involved in this loss and the need for and the requirements of an effective hearing conservation program are discussed. The legal and legislative history of compensation for hearing loss is briefly reviewed. A review of statutes is not attempted since several States have recently modified) or are in the process of modifying their laws regarding permissible noise exposures) required hearing protection) and/or compensation for hearing loss. A review of other aspects of the problem of industrial noise in terms of medical, physiological) and psychological frames of reference is included. A hearing conservation program is described in detail. Appendixes detailing the names and addresses of a few equipment suppliers are included. References are provided for those who may wish to delve more deeply into the medical, technical, and scientific considerations of noise and its effect on man.

Jan 1, 1972

By A. A. de Gast, R. B. James

"The metal content of ore blocks can be calculated by the use of many different methods. These methods range in sophistication from manual calculation to computer. oriented techniques. In this case a cubic polynomial regression model is developed to depict the grade distribution of an orebody. Mine production, in stope dimensions, is then simulated on a computer to predict the output of metal content. The volume, grade and variance of the grade are estimated by triple integration and matrix algebra. A case study shows reasonable agreement between the results from the mathematical model and the mine geologists' estimate of production and ore reserve grade and tonnage."

Jan 1, 1972

By N. N. Moebs

The atmosphere in part of an air-sealed coal mine was monitored continuously through a drill hole for oxygen content to determine the effectiveness of sealing a mine against the entrance of air and the major force that caused the phenomenon of mine breathing through the overburden. The differential pressure across the seal and the barometric pressure on the outside also were recorded. A general correlation, obtained between the oxygen level, differential pressure, and barometric pressure, indicates that changes in air pressure are the cause for periodic replenishment of the oxygen in the mine. Mine effluent quality was determined by conditions in many sections of the mine and could not be related to the oxygen level at the drill hole.

Jan 1, 1972