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By Neville G. W. Cook, John Kemeny

Utilizing the principles of elastic-brittle fracture mechanics, stress-displacement relationships are derived for an elastic solid containing a slip plane consisting of various configurations of collinear arrays of cracks. These models take into account the heterogeneous nature of slip planes as observed in the lab and in the field, and are relevant to the behavior of rock containing faults, joints, bedding planes, and fractures. All of our models exhibit slip weakening behavior, and show regimes of both stable (aseismic) and unstable (seismic) deformation. For given configurations of cracks and applied boundary conditions, our results show explicit ly the energy released through unstable crack growth. For instance, it is found that two equal length cracks growing together release more seismic energy than, say, a large crack growing into a small crack. Also, by allowing cracks to coalesce, our models show multiple stick-slip events without crack healing or other geochemical means.

Jan 1, 1986

By Neil Donnell, O&apos

MODERN mine maps are largely a product of evolution. The first mine maps used in the west were old composite maps with all the levels plotted on the same sheet. The composite was widely used and occasionally is seen even now. This type of underground map had serious limitations. One was the development of an indecipherable complex of workings around steep shafts. The other limitation was that of size; often when a working passed the limit of the sheet no map was made of it. These old maps have been superseded by the single level maps, laid out in squares or rectangles which can be expanded indefinitely in all directions. This produces a system capable of unlimited expansion in three dimensions, with all the detail of every working clearly marked and legible. A good set of mine maps should be laid out in blocks, all blocks of equal size. Each block should be limited by plane coordinates without overlap on bounding map quadrangles. At all times the direction of North should be indicated as an aid in remembering bearings of underground workings. It is desirable that all maps of whatever scale be plotted on sheets of uniform size. In fact, it is possible to make nearly all underground maps, surface maps and sections on sheets of the same size.

Jan 9, 1950

By T. A. Rickard

The use of the verb in this mood is not as common as formerly: at the time, for' example, when the Bible was translated and the plays of Shakespeare were written. Nevertheless it is an essential part of literary English. In editing the `Mining and Scientific Press' I do not insist upon the use of the subjunctive in articles that are contributed from the outside, but it is deemed proper in all our editorial writing. To speak plainly, the subjunctive is I a mark of scholarship; it is ignored by those that are not particular in such matters, and unfortunately it is a source of perplexity to many that are entirely unfamiliar with the use of it. Therefore, as an editor, I think it well to allow the indicative mood to be used by contributors in sentences in which, to be strictly correct, the verbs .should be in the subjunctive mood. The fact that most subjunctives are indistinguishable in form from indicatives is another cause of trouble to the uninitiated.* For example, the verbs in such phrases as "Suffice it to say ", "So help me God ", and "God save the King" Fare in the subjunctive. One reason why the subjunctive is becoming uncommon is the growing habit of expressing the subjunctive meaning by aid of auxiliary verbs that are coupled with the infinitive; thus: "It will suffice' to say" and "May God save the King". The subjunctive is common in subordinate clauses, and that is how it obtained its name, `subjunctive', meaning * The student is referred to `A New English Grammar', by E. A. Sonnenschein, published by the Clarendon Press, Oxford. This textbook (see pp. 60-71 in Part III) discusses the subject luminously.

Jan 1, 1931

By W. S. Ayres

BACK in the early nineties the old Dickerson iron mine in Morris county, N. J., was operated by a vertical shaft 850 ft. deep and by a continuing slope for more than 1000 ft. more 011 an incline of 65", together making the vertical depth about 1800 ft. I was then the general superintendent there. This mine, named for a former governor of New Jersey, had been worked more or less continuously from long before the American Revolution and up to this particular time. The pumping equipment was of the old-time Cornish type, with its long pump-rods running down the vertical shaft and the slope to the sump at its bottom. It was operated by a large flywheel engine in the engine room and all angles were turned by the usual bobs. Saturday was the day fixed for lowering the "suction" into the deepened sump at the bottom of the advancing slope. The mine foreman had gone down with the morning shift to superintend this very vital and particular work, which consisted not only of lowering the "suction" into the sump immediately after the pump had been stopped, but of securing it to the rock and putting in the added sections of column-pipe and of tightening up the numerous bolts at their joints, all before the water rose to the point of working. At an appointed time during the forenoon I had agreed to go down into the mine and join the mine foreman in consultation over any difficulties that might have arisen. At the time agreed I went down by the cage to the bottom of the vertical 850-ft. shaft, and then by ladders down the slope for over 1000 ft. more.

Jan 1, 1930

By AIME AIME

ALMOST as many attended the annual dinner this year as last, when the presence of Mr. Hoover was such an attraction that almost two-thirds more than had ever attended before were present. Only by putting the late comers at tables in the balcony could everybody be accommodated. Past President De-Golyer was the toastmaster and in opening the post-prandial exercises referred to the regrettable fact that this was the last of the long series of dinners which have been held at the Waldorf, as the hotel will be torn down to give way to an office building before another year. To the delight of the gathering "Oscar" appeared and, in a delightfully brief but characteristic speech, referred to the long association that had existed and hinted that a new Waldorf-Astoria may arise, where the Institute could continue to gather annually in an enlarged replica of the room they had met in so long. Before taking up the presentation of the medals, Mr. DeGolyer referred to the Institute's "Legion of Honor," the 34 men who have been members continuously for over fifty years. For various reasons only five of them, W. S. Ayres, F. G. Corning, Henry D. Hibbard, A. F. Schneider and Arthur Thacher, could be present. They were all seated at the speaker's table, and W. S. Ayres, 56 years a member, as the dean of the group, was called on to respond for them all. He said: "The introduction I have just received would indicate that this particular group of men to which I belong is considered by the chairman to be a group of real antiques. Possibly you are questioning the accuracy of his judgment. I hope you are, although there may be some first-sight evidences tending to substantiate the view held by the chairman.

Jan 1, 1929

By Joe M. Short

More than eighty years ago, in what we generally consider a more leisurely age, workers and engineers began the construction of the longest railroad tunnel in the world. When completed, the Simplon Tunnel ran more than twelve miles through the alps to connect Switzerland and Italy. Work began in 1898 and the tunnel was completed in 1905. In all it took about seven years to build one of the world's great tunnels. More than seven years ago, in what was hoped to be a rapid and constructive to the deaths of 38 workers in two spectacular tunnel disasters in 1971, the secretary of Labor's Construction Advisory Committee on Safety and Health began in January 1972 a search for an effective standard on tunnel safety. Much hard and useful work has been done, especially by the construction advisory committee' but more than seven years later, we still don't have a tunnel standard. We may speculate that, when the Simplon Tunnel was completed, workers and their bosses assembled to celebrate their achievement and to count their casualities. We have no need to speculate on the lack of achievement up to this time. An so far as I know, the bureaucrats have suffered no casualities except perhaps some unreported cases of ring-around-the-color. The only moral I can draw from all this is thai it is easier to penetrate solid rock than it is to get through bureaucratic fog. We can only hope that OSHA will finally take advantage of the work which was finished years ago and complete the actions necessary to give us a tunnel standard. Having made my point, I could stop my remarks right now; but

Jan 1, 1979

By J. C. Rudolph

"THE TOPIC on which I am speaking this afternoon is ""The Future of the Canadian Oil Industry.'' At the time of C + 100, we should take a searching look at ourselves, an honest appraisal of our achievements and a forthright accounting of our shortcomings as well as the uniquely Canadian aspects of this industry. I would like to put before you some of my views on the direction we are taking in the exploration field and in the production field. I would also like to speak briefly on some of our problems and the role of the various segments of our industry in solving these problems.First of all, let us look at the exploration picture. We are in the midst of an exploration boom. There were 133 seismic crews active in Western Canada this winter, the highest since 1957, land prices are appreciating rapidly, Canadian oil reserves increased + 16 per cent during 1966, there is a great demand for technical personnel of every kind and the whole industry, except the drilling segment, seems to be prospering. This surge of activity has its roots in two major occurrences. The first of these was the change in the pro-ration system in Alberta, the major producing province, accompanied by the change in spacing pat-terns. The proration change was designed primarily to encourage in-creased exploration and it has certainly had this effect. It has also had the unforeseen effect of put-ting everyone into what we, in the oil business, call ""elephant hunting."" In other words, the days of the development of barely economic, marginal fields are over. Oil companies today are only interested in high-reserve, high-productivity, high-quality reservoirs."

Jan 1, 1968

By W. R. Horn

"WHAT I PROPOSE TO DO is to review or report very briefly and generally on the most important subject areas of environmental concern within the mining industry and to indicate the progress being made. First, however, it seems to me both appropriate and necessary to refer to what I said in an address to the CIM Annual Western Meeting, in November 1971, in Vancouver. At that time, I tried to convey: that the awareness and alertness of this far-flung and diversified industry was sharply on the up-swing; that the knowledge of helpful technology for the abatement of pollution by water and solids was significantly increasing; that most mines were doing something about it; that many had already achieved a recycling of process water to a really significant extent; that progress was being made - though not without considerable difficulty - on the large-scale neutralization and subsequent chemical treatment of acid- and metals-bearing waters; that increasing work was being done by individual mining companies on methods for the vegetation of completed tailings impoundments; and that it had been possible to develop a meaningful estimate of the amount of money to be spent by the industry on environmental control measures during the period 1971-75 (as much as $500,- 000,000 ) . Reference was also made at that time to the constructive work in hand toward the fixation, elimination or dispersion of sulphur from smelters and to the considerable attention which was being given by the indust(y itself toward in-plant problems, e.g., dust and noise. Finally, note was taken of the fact that the inclusion of environmental control costs in the pre-operational financial provisions of new mining operations is now established practice."

Jan 1, 1973

By J. Solano

El sostenimiento con pernos de roca requiere de estudios que determinen cuáles son los factores que influyen en el proceso de acción recíproca entre la roca y sus elementos. En ese sentido, el objetivo del presente trabajo es mostrar los resultados de las investigaciones realizadas, basadas en el principio de deformación y compresión sobre la roca en el mismo campo de trabajo. Para ello, es necesario considerar que el desconocimiento de las propiedades físico-mecánicos de la masa rocosa y de instrumentos de investigación, limita el estudio a la determinación del anclaje y la pérdida de tensión de los pernos.

Nov 20, 1972

Alexander Forsyth, Southport, Me. (communication to the Secretary): In Mr. Irving's able and interesting paper he describes minutely the appearance of the wolframite and its association with the refractory siliceous gold-ore. He also describes this gold-ore, but fails to mention the important pockets of metallic gold found in the Lead City occurrence of it. I use the term " metallic " in preference to the more usual " free," for it has been found that this gold is not easily amalgamated. Metallic gold is comparatively rare in the refractory siliceous gold-ores of the Black Hills; hence its occurrence in considerable amounts in the Lead City wolframite district deserves notice. I possess a beautiful specimen from the Harrison mine. It is a lump of drusy, granular ore, about 6 in. in diameter. The gold .is " shot" through it in large and small pin-heads; and in two specially oxidized areas, each about 11/2 in. in diameter, it is peppered full. The famous " Grantz strike," made in the Lead City wolframite locality, produced many beautiful gold specimens. This district affords an excellent example of the repeated discovery of new mineral values upon old ground. By reason of its proximity to the Homestake vein, this wolframite deposit was inevitably traversed many times by experienced geologists, mineralogists and mining engineers, who evidently must have thrown aside, with no thought of wolframite, the lumps of " black iron " lying about. I have the admission of an able geologist that, six months before the wolframite was discovered, he visited some of the very mines where it occurred, and passed it by as magnetic iron-ore. At the time of the discovery, the mineral was scattered over the gold-mine dumps in no small quantities, having been culled as worthless out of the gold-ore. It remained for

Jan 1, 1902

By W. A. Vine

Next year, in 1964, Butte will celebrate its Centennial. It was in May, 1864, that the first recorded mining activity took place. During that summer, several rich placers were found on Silver Bow Creek and its tributaries, and a gold rush followed. As placer mining proceeded in the creek beds, the quartz lodes on the hillsides were located and the veins were prospected. Mining in Butte entered its second phase when the rich silver mines, the Alice, Moulton, and Lexington, were opened. The silver boom lasted until the decline in the price of silver in the early 1890's forced the closure of many of the mines. An indication of the beginning of the copper mining era in Butte was in 1866 when it was noticed that green copper carbonate discolored some of the, lode material. It was not until ten years later, however, that the Anaconda and St. Lawrence claims were located by Michael and Ed Hickey. The claims were sold in 1880 to Marcus Daly and in 1881, Daly obtained financing and organized the Anaconda Silver Mining Company to exploit the vein The silver venture was a failure because of the predominance of copper which diluted the bullion to only 400 fine.

Jan 1, 1963

By Oliver C. Ralston, Foster Fraas

"INTRODUCTION The predominant characteristic of powdered mica is the thin -plate shape of the particulars, and the thinner the plates, the more enhanced is this characteristic. Consequently, it is frequently desirable to grade mica according to the thickness of the plates. Concerning the various possible methods for grading mica, very little has been published. There is also no information on the relative quantities of mica per given range of plate thickness. This paper presents a graphical method that shows how these quantities are distributed and how the different methods of grading compare.CUMULATIVE BULK DENSITYBulk density, which is an indirect measure of the plate thickness, was determined in a small cylindrical cup of 3.37 cubic centimeters volume. The mica was placed in the cup under a standard procedure. The densities thus measured checked these determined in a 273 cubic centi¬meter cup with less than a 2 percent error.In calculating cumulative densities it is important to know how they are averaged. In any grading operation the bulk density of a series of fractions is determined. Starting with the lowest density fraction, the cumulative percent under-density can be calculated through the various fractions. It is possible that quantity may be measured by volume or weight and that the averaging may be done by a number of methods. However, experimentally it has been shown that the quantity must be by volume and that the averaging must be arithmetic. This is illustrated in table 1, in which the calculated and actual bulk densities are listed."

Sep 1, 1942

By Clarence Hardy Long

In January of 1969 the United States Department of Health, Education and Welfare, through the National Air Pollution Control Administration, published a series of Air Quality Criteria (4'S) and Control Techniques (6,7) for air pollutants in compliance with the 1967 Clean Air Act which will affect the operation of all fuel burning equipment in the very near future. The design of equipment for the future which will use fossil fuels will also be affected. The purpose of this paper is to discuss some of the modifications which might be anticipated in the future for fuel burning equipment. One class of the several air pollutants looked at first by the USDHEW was the sulfur oxides. Other pollutants, such as nitrogen oxides, will be studied and controls for these will supposedly be written in due time. The obvious use of low-sulfur fuels, coal, oil and natural gas is suggested by the Control Technique(6). Conversion to other sources of power, such as nuclear energy and hydropower, is also suggested. The statement is made that since possible hydroelectric sources are limited and nuclear plants are not yet available on a large scale, the changeover to these sources of power will not be overnight. The bulletin (6) suggests that one possible solution in some areas may be the use of low sulfur coals for short periods of time during periods of severe air pollution. A curve showing the effect of this was given in the 1969 April issue of the Power magazine, where A. E. Boyer and F. B. Kaylor of Stone and Webster also described a computer program called DOSAGE which might be used to check weather, temperature, humidity, wind direction and velocity, and sound an alarm when that 0.1% of the time per season is here that requires the use of low-sulfur fuel. Inversion is eminent! Once this has passed operation on regular fuel may be resumed. This would mean a separate storage

Jan 1, 1970

By P. K. Muduli

The number and the type of trucks and shovels are two important factors in determining the optimal design parameters of an open-pit mining system. Characteristics of trucks' arrival and service-time distributions determine the performance measures of a truck-shovel system when it is modeled as a closed queuing network. In all of the previous analytical queuing studies of truck-shovel systems, trucks are assumed to be identical with respect to their arrival and service-time distributions. This assumption, although desirable for reducing computational difficulties, causes either underestimation or overestimation of the performance measures depending on the number and type of equipment used in the model. The relative error in performance measures could be significant when the number of different types of trucks and shovels is large. In this paper an analytical method is proposed to model the truck-shovel system as a multiple-chain closed queuing network. This approach would provide the capability of estimating system performance measures for planning purposes when the truck fleet is not necessarily composed of identical trucks. An example of truck-shovel systems is discussed to show how the incorporation of different types of trucks does affect performance measures.

Jan 1, 1996

By B. F. Fackenthal

For the past year we have had in use at the Durham furnace a set of hollow pig-patterns made of iron, which have given such satis factory results that I think a description of them would be of interest to the members of the Institute. Before the introduction of these iron patterns, we used the ordi nary wooden patterns, made in the usual way with straps of iron along the sides to protect the corners from wearing off. The size and shape of these wooden patterns are shown in Fig. 1. When the patterns were new, the pigs weighed about 130 pounds each, and were uniform in size, and the moulding was clean. But constant use soon wore the patterns away; and at the end of a few months, the pigs had become, in consequence, so much lighter that the moulding, daily, of several additional beds was necessary to accommodate the same quantity of iron. As the patterns wear away, the moulding becomes ragged and the pigs rough. Moreover, wooden patterns are often destroyed by fire. I have known an entire set to be destroyed by a break-out of iron. The iron pattern which I have designed is free from all the objections to the wooden pattern, being not only more durable, but, in the long run, far cheaper. The iron pattern having the same shape and size as the wooden one, is made of the best flange-iron, of No. 13 gauge. After the sheets have been cut to the proper size, three heats are required for the flanging. At the first heat, each piece is stamped in a cast-iron form, which gives the proper shape to the bottom part of the pat-

Jan 1, 1889

By I. N. Knap

Discussion of the paper of HOWARD R. HUGHES, presented at the Now York meeting, February, 1915, and printed in Bulletin No. 99, March, 1915, pp. 629 to 635. I. N. KNAPP, Ardmore, Pa.-The claims made in the paper for the Sharp & Hughes cone bit are modest. I have used it with satisfactory results. It is a wonder for eating through hard, brittle rock; it will drill through iron pyrites that the fish-tail bit cannot enter. Soft ground is apt to contain concretions that are much harder than the containing ground. ?We have at times in drilling with a fish-tail bit thought the hole was partly in such hard material and partly in soft, thus making a difficult place to drill past in the ordinary way. By changing to a Sharp & Hughes cone bit such obstructions were easily overcome. This cone bit has greatly widened the range of work that may now be profitably accomplished by the hydraulic rotary method of drilling. It is not, however, adapted to drill soft or sticky ground, the old fish-tail bit being better for such purposes. The fish-tail bit usually scrapes its way through the material drilled, but not always. I believe at times it cuts and chips in soft friable rock. That is, the bit seems to bite into the rock, and when sufficient torsion is put on the drill stem it breaks its hold and jumps around and chips the rock from the bottom of the hole, like a stone cutter's chisel, and then takes another hold. This condition occurs only in friable material when the bit is sharp and the feed properly controlled. The Sharp & Hughes cone bit is a most valuable -tool for the rotary driller.

Jan 5, 1915

By Steven A. Elmquist

INTRODUCTION R&D activities are needed, at a minimum, for a company's competitive survival followed in importance by the growth and diversification of the company. For most industrial companies, however, R&D is the business area that has been the most difficult relative to confident long-range financial commitments and effective control and relative to its value as a long-term investment. Investors look not only at the current profitability of the company but increasingly at the plans, actions, and quality of the personnel in position to improve the market position and profitability of an organization. "The strongest predictor of investment value is the degree of innovation of the 'company.' I believe this is true of both strategic planning and R&D activities." R&D is the lifeblood of a company's future. If this basic premise-R&D for survival and growth-is believed to be true, why is it necessary to "Sell R&D in your organization? My personal experience, in a number of organizations, is that R&D budget is perceived as a business element area that could be delayed or reduced to improve the bottom line during difficult business conditions. I believe the following quote speaks volumes about this subject-"There is only one thing I know for certain about research, and that is it costs money-lots of it." -Unnamed, Hard- headed Financial Executive. A business must make money and be profitable in order to maintain and create jobs, pay taxes, cover working capital and costs of goods sold, and most importantly, create value for its shareholders. The foremost element of selling R&D, therefore, is to consistently demonstrate the R&D group's contribution to the bottom line.

Jan 1, 2004

"Since all gold mills must sooner or later be cleaned up for permanent shutdown it was felt that a record of what was done at one mill might be of some help to those who will have to do the same job in the future,In cleaning up the mill of Delnite Mines Limited, I had an advantage that most mill superintendents will not have in that I started up the mill and was there until it was shut down, It was also known for two years approximately when the shutdown would be and for a year almost the exact time. This, of course, made careful planning possible and enabled me to get advance information that wouldn't have been available had the shutdown come unexpectedly,Early in 1964 calculation of ore reserves and the known number of working places available indicated that the mine would run out of ore sometime in August or September but not later than October, The time of course would vary with the number of competent miners that could be retained until the shutdown. Since the mining method used exclusively on the ore then remaining was cut and fill, it was known that once mining operations ceased it would require at most two days to crush and grind the last of the ore.In March 1 964 I took samples of the concrete floor under the precipitation presses, in the flux room and furnace room of the refinery and from the assays obtained proved that there would be no profit in breaking up the concrete to recover the gold from it, Samples taken from the top half inch of the concrete floors assayed less than 0, 10 oz per ton,"

Jan 1, 1966

H. S. COE, St. Louis, MO. (written discussion *)-I feel much gratified that Mr. Mishler has confirmed those principles of slime settlement expressed by Mr. Clevenger and myself. I wish to state that, when we wrote the article referred to by. Mr. Mishler we had not seen his earlier article in which he gave a formula to be applied to the settling rate off feed pulp for determining thickener area required at El Tigre. It has been my experience that in cyanide work the settling area required is determined by the settling rate of the feed pulp for perhaps 20 per cent. of all of the ores to be encountered. For the other ores, the area required is greater than that indicated by the settling rate of the feed and corre-sponds to the settlement of a somewhat thicker free-settling pulp. Mr. Mishler, in his paper, has thoroughly outlined a set of tests for determining thickener capacity, which, if carefully carried out, should be entirely reliable, provided allowance is made for changes in the mill feed from time to time. Two features of his paper, I, believe; need comment. In speaking of the time required for slime to flocculate after being fed, Mr. Mishler quite properly states that the actual settling rate for the feed pulp can-not be that of completely flocculated pulp because of this time lost in flocculation. It seems to me, however, that this feature cannot be of very great importance, for the following reason: The upper zones of pulp in a thickener may be, and often are, as thin as the feed pulp. If, therefore, the feed be introduced at sufficient depth below the pulp surface to prevent agitation at the surface, there will be ample time for it to become flocculated before it becomes the surface layer, and it, will

Jan 1, 1918

By T. E. Walsh

I will address two important alternative energy resources, solar and geothermal, with emphasis on their potential application in electric power generation. As a result of this presentation, I hope to leave you with a realistic view of the principal technology options that are being developed or that are available. Solar Types of Collection In terrestrial solar applications, the biggest challenge is to find ways of collecting the sun’s relatively low intensity energy so it can be converted economically to useful thermal or electric energy. Fig. 1 shows that there are both natural and technological ways of collecting solar energy. In nature we find that solar energy aids in the production of biological growth, rainfall, and wind, all of which can, in one form or another, be put to use in the production of heat or electric power. The sun’s rays also are collected and stored naturally in the form of heat in the upper layers of the ocean which can be put to use in the production of electric energy by means of ocean thermal energy conversion (OTEC) approaches. On the technological side, the sun’s rays can be intercepted by materials that directly absorb and convert its energy to low-grade heat, or by mirrors or lenses that focus the rays onto a material to produce high-temperature heat. The higher temperature systems can be used to drive efficient heat engines in the production of electricityy. The sun’s rays also can be collected on photosensitive materials, in either a direct or concentrated form to generate DC electricity directly. The systems I will discuss employ all of these means of collection and conversion, excluding biological and hydroelectric. The former is too exi

Jan 9, 1980