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By B. M. Larsen, W. E. Shenk, T. E. Brower

Shortly after our previous paper on this subject was printed1 we located a source of uncertainty in the results arising from the unexpected fact that hydrogen slowly reduces silica at 1100" C. in presence of iron, even when the iron nowhere touches the silica, although in absence of iron it does not do so. This difficulty has been completely obviated by the use of a small high-frequency furnace, which enables us to heat the specimen for analysis without raising the temperature of the silica vessel to a point at which any appreciable reduction of the silica glass occurs. We now describe this modification of procedure, and present some typical results obtained with it. For any given specimen of steel, the results are entirely definite and reproducible, but their precise significance is still open to some question, as indeed is true of all methods of oxygen determination SO far developed. Further elucidation of this question is to be expected from the cooperative comparison of the several methods now under way under the auspices of the Bureau of Standards at the instance of the Iron and Steel Division of the A.I.M.E. Apparatus The final form of apparatus we have used is identical with that described and illustrated in our previous paper, except for the substitution for the Globar furnace of a small high-frequency furnace actuated by a vacuum tube oscillator2 0f about 1.5 kw. capacity, and for a slight modification of the containing vessel. This transparent silica vessel is illustrated in Fig. 1 of this paper. Its enlarged portion is about 5 cm. in diameter and 13 cm. long. The silica tube for inlet of hydrogen is fused into this bulb and ends beneath the metal "bucket" holding the steel sample. This sample is in the form of fine millings. The "bucket" is suspended by a platinum wire from the cap of Pyrex glass. The high-frequency

Jan 1, 1934

By W. A. Bruce

This paper covers the theory and present state of development of an apparatus for the nonmathematical analysis of complex problems of reservoir and well behavior. At the present stage of development of this apparatus, it is capable of solving the water-drive problem of any reservoir performance for which a mathematical solution has been presented in the literature, either on the basis of steady or unsteady-state flow analysis. The theory is presented for the extension of the scope of this analyzer along the lines of the present development. The resulting apparatus should be able to solve reservoir-performance problems previously thought too difficult for practical solution by mathematical means. As an illustration of its operation and present scope, the analysis of a reservoir problem and synthesis of expected performance is presented. Introduction In this method† of analyzing problems of petroleum-reservoir and well behavior, the porous continuum of the reservoir is assumed to be divided into small blocks, or units. Each block is assumed to be small enough so that for a material balance on the fluids in the block an average pressure for the block can be used. In analyzing reservoir behavior from this point of view by mathematical means, a set of simultaneous difference equations would be obtained (two for each block), which must be solved or combined into a partial differential equation. In the method to be described here, instead of solving these sets of equations analytically, electrical units are constructed, which will behave in respect to the flow of electricity exactly as the reservoir units behave under various conditions of fluid flow. The electrical units are then wired together in the same way that the reservoir units are connected naturally by virtue of their geometrical locations and shapes. Fluid-Flow Equations Consider a block in a reservoir. Assume that reservoir fluid (or fluids) is flowing in at one face and out at the opposite face, and that the block is small enough so that at all points the stream lines are within one degree of perpendicular to the face. Furthermore, assume that the pressure, pi, at the upstream face (Fig, I) is not more than one per cent greater than P2 the pressure at the downstream face. A material balance will show that the mass of fluid flowing out less the mass of fluid flowing in will equal the change in density times the fluid volume. This is expressed in the equation:

Jan 1, 1943

By F. W. McQuiston, L. J. Bechaud

3.2-1. Introduction. Much has appeared in the technical literature on theory of sampling (18, 37), weight of sample required in relation to particle size (28), probability of error in sampling (3), and statistical analysis of sample data (20). Each industry, whether it be copper, iron ore, or coal, has its own standards and methods. All of the rather extensive theoretical treatments appearing in published literature on sampling apply to material already on hand such as coal, iron ore, or copper concentrates in rail cars, or in moving streams such as on conveyor belts. The attempt usually is to apply statistical techniques in order to improve reliability and precision in sampling, and to reduce differences between the analyses of seller and buyer. In contrast to this type of sampling, very little has appeared in the literature on sampling a virgin deposit from the metallurgical point of view. Perhaps it would he more descriptive to designate this point of view as "Gm-metallurgical," since geology is inextricably interwoven with metallurgy in gaining an understanding of the complexities of a deposit, eventually leading to a definition of mineable reserves, with the development of a flowsheet and engineering criteria for the planning of a successful and profitable operation. The degree of cooperation between these two departments often determines whether the processing plant is a success at the inception of operations, or whether expensive changes and modifications must he made, with the plant finally reaching rated capacity at some later date. The first concern of the metallurgical department should be to establish proper accreditation of the samples which will be used in any ore-testing campaign. It should he made mandatory, as part of operating management policy, for the responsible metallurgist to he aware of the significance of the samples and to become intimately knowledgeable in all aspects of metallurgical behavior and response to treatment of all varieties of ore in the deposit under consideration.

Jan 1, 1968

By John C. Cook

Long-wave short-pulse radar has been shown capable of exploring to distances of several hundred feet through massive, dry rock salt. Exploration distances of 30 to 60 ft through bituminous coal and massive limestone, respectively, have also been demonstrated with low-power experimental radar equipment in underground mines. Working ranges up to 250 ft in limestone and coal are considered feasible. Radar reflections should be produced by all large electrically contrasting objects such as fault gouge masses, wet shattered ground, metallic mineralization, adjacent mine workings (dry or flooded), and abandoned drill holes. It is believed that radar can locate such obstacles in advance of underground mining through all massive rocks of low free-water content, including many igneous and metamorphic rocks. Three years of studies and experiments in radar exploration through rocks are reported.

Jan 1, 1974

By P. F. Gnirk

Consideration is given to creater formation with shallow, contained, chemical explosions in rock masses which exhibit different inherent physical and mechanical properties as determined by standard laboratory techniques. The primary purpose is to determine whether or not a simple but useful generalized correlation can be established between explosive crater formation and one or more common rock properties. Such a correlation could be beneficial in predicting with some degree of reliability the size of a crater which could be expected in a particular rock type for a given input of explosive energy. A series of crater formation experiments employing constant weight charges of Gelex 2 explosive was conducted in five submembers of the taconite formation at the eastern end of the Mesabi Range in northeastern Minnesota. Five mechanical and physical properties-unconfined tensile and compressive strengths, Young's modulus of elasticity, longitudinal wave velocity, and density-were determined by conventional laboratory techniques using core samples from the taconite submembers. Although insufficient data were obtained to warrant the use of mathematical methods in the determination of empirical relationships, the results provided a fairly strong indication that with an increase in magnitude of any one of the five rock properties definite decreases in the optimum crater volume and surface area occur. Furthermore, for a constant explosive energy input, the presence of bedding planes and joint systems in a rock mass influences the formation of craters in such a manner as to increase the volume of rock broken substantially above that expected from the same rock mass without joint systems and, in particular, without bedding planes.

Jan 1, 1968

By C. S. Simons

The conversion of a successful research and development effort into a money-making business venture requires careful attention. Problems of a business nature, such as market size, product selling price, raw materials and fuel availability and cost, financing factors, local and national taxes, licensing arrangements, etc. must, of course, be considered and resolved. In addition, the technical questions involving the scale-up of pilot plant or laboratory results to the full-scale plant must be resolved in order to avoid the financial disaster that attends a major delay in the startup of a commercial facility. The very difficult and demanding task of providing the interface between the research laboratory and the profitable metals processing plant will be discussed with examples from the author's extensive experience. After I had accepted the invitation to present a paper on the above subject of the interface between R & D and production operations, I began to give some serious thought to the subject. The program chairman had told me, in conveying the invitation, that what the committee had in mind was a discussion of positive and negative, forces in that interface, based on "gray-hair" experience. I am, therefore, at least physically qualified! My first reaction was one of mild shock; after over twenty years in the direct pursuit of the conversion of research and development findings into plant operations, I had never tried to sort out my , experience into a formal system of DO'S and DON'TS for the edification of posterity. However, after a little further reflection, I realized that this carries no stigma. No one has been able to formulate such a set of rules, and it is not really very likely to be done. Particularly if they are to be practical. I shall therefore settle for a more modest goal; I will simply discuss the factors that I have come to believe are the most critical in insuring that re- search and development results are converted into successful operation.

Jan 1, 1973

By David Baker

Our large modern blast-furnaces, equipped with ore-bins, larries and mechanical means for putting stock into storage, withdrawing it therefrom, and charging it at the tunnel-head, are indeed wonderful in capacity; yet, it is admitted that, with some notable exceptions, they have disappointed us in economy—that is, in the items of low fuel-consumption, uniformity of product, freedom from slips, and reduced cost of repairs and relining. The manager who estimated the cost of pig-iron to be made in a modern plant, by taking the costs of the hand-filled furnace and deducting the amount to be saved by the mechanical appliances, has been surprised, in many cases, to find that unfavorable results in these items of economy have greatly reduced his expected gains. Is there any reason why the fuel-consumption should be greater for a modern furnace than for an older stack using the same mixture ? Certainly the equipment is much more complete, and the trouble, therefore, must lie in the management or in the character of that equipment. Everybody knows that intelligent and vigilant management is a prime requisite: that any neglect of a detail, though it may not be felt that day or week, will surely sooner or later make its appearance as an increased item of cost. But to hold the furnace-maaager responsible for the relatively poor work of the modern blast-furnace would be, I am convinced, a great injustice. For its management has received much more study and care than was given to the older types. Many furnace-managers have lost their health through worrying over this problem, and some hare lost their positions, being held responsible for results made inevitable, as I believe, by the equipment provided for them.

Jan 1, 1905

By Auguste J. Rossi

We cannot expect, within the limits of this paper, to treat this subject exhaustively, but will endeavor, in the following, to present it in as concise a manner as is consistent with a clear exposition of its importance. Ores of titanium, titaniferous iron-ores (that is, iron-ores containing a notable amount of titanic acid, TiO2,, say not less than 5 per cent., generally 10 to 20 per cent., and frequently more, up to 40 per cent. or thereabout), occur all over the world in immense quantity, " in mountain masses," constituting in some localities, as in Sweden, Norway, Canada, the Adirondacks (N. Y.), in North Carolina and other States of the Union, the geological formation itself, the igneous rocks having, in many places, been so permeated with the metallic oxides as to justify their being called iron-ores. As a rule they are Bessemer ores, quite free from phosphorus and sulphur, though not invariably so. When the percentage of titanic acid is very high, that of the iron is low, but the proportions do not necessarily vary in the same ratio; that is, a rich ore may contain more titanic acid than one lower in iron. The percentage of iron varies, being as low as 35 to 36 per cent. in real ilmenite. It is more generally not less than 50 to 55 per cent., reaching often an average of 58 to 60 per cent., and as high as 63 to 65 per cent. It is obvious that if these ores were to be considered in the same light as other iron-ores, equally rich in iron, they would form an excellent stock for blast-furnaces for years to come, as their supply might be called inexhaustible, and they could

Jan 1, 1903

By W. K. Lewis

During the last decade the petroleum refinery engineer has made great progress in achieving a better understanding of the physical behavior of hydrocarbon mixtures, with particular reference to their pressure-temperature-volume relationships, the mechanism of the evaporation of liquids, the condensation of vapors, including the changes in composition, and the heat effects accompanying them. With the new insight into the mechanism of movement of oil and gas through the formations in which they occur, achieved by the production engineer, it is clear that the latter will need to utilize in the solution of his own problems much of the information outlined above. It is the purpose of this paper to outline the portions of that information that seem most certain to prove of importance in production work. Properties of Pure Hydrocarbons While it is true that petroleum always consists of highly complex mixtures of hydrocarbons, none the less understanding of the behavior of the mixture must be based upon a knowledge of the properties of the pure components. However, in view of the tremendous number of hydrocarbons existing in petroleum, the determination and formulation of the properties of all of them would seem a discouraging task. The difficulty of the situation is increased by the undoubted facts that the overwhelming majority of chemical individuals in petroleum have never been isolated as pure compounds, none of their physical properties have been determined and even their chemical constitution is unknown. The situation would be hopeless were it not for the fact that certain extraordinary correlations of important properties of various hydrocarbons have been discovered which make it possible to predict those properties for a given chemical individual on the basis of a very limited characterization of it. Thus one can predict the vapor-pressure curve of an unknown hydrocarbon over a considerable range from the knowledge of a

Jan 1, 1934

By E. C. Truesdale, R. K. Waring

THE Research Division of The New Jersey Zinc Company (of Pa.) has conducted, over a period of years, numerous tests of the reducibility of various zinc ores and the reactivity of various kinds of coal, using a number of different experimental methods. Most of these tests have involved the reduction of mixtures of ore and coal. In such cases the following simultaneous reactions are believed to be mainly responsible for the production of zinc, as was shown by Bodenstein1 some years ago: ZnO + CO = Zn + CO2[I] C + CO2 = 2CO[2]. Each of these reactions is dependent upon the other for the supply of CO and C02, respectively, and the over-all rate of formation of zinc vapor will be determined by the slower of these two reactions. An analogous pair of reactions sometimes of importance is: ZnO + H2 = Zn + H2O[3] C+ H2O=CO+H2[4] While it is possible to obtain an indication of the relative reducibility of various ores, or of a fine versus a coarse ore, by testing them with a given coal, and while coal reactivities may be measured in a corresponding manner, a more direct determination of relative reaction rates is possible by carrying out the desired reactions, such as I and 2, separately and under reproducible conditions. It is one purpose of this paper to present some of the results that have been obtained by the latter method. C. G. Maier2 discusses the relative rates of reactions I and 2 and concludes that while at relatively low temperatures reaction I is faster than reaction 2, this difference becomes less with increasing temperatures, although at smelting temperatures reaction I is still the faster. He also says (p. 48), "At temperatures . . . between 1100° and 1300°C the zinc oxide reduction reaction is intrinsically more rapid than its physical limitations; that is, it is limited by gas diffusion rates." In the course of numerous reactivity tests involving the separate use of reactions and I and 2, we have obtained data that show by direct experiment, we believe for the first time, the correctness of Maier's statements concerning these reactions. We also include data on the relative rate of reaction 3, involving reduction by hydrogen. Finally, some interesting results obtained by carrying out the reduction of a zinc ore-coal briquet in streaming atmospheres of nitrogen, carbon monoxide and hydrogen, respectively, are presented.*

Jan 1, 1941

By Cyril Smith

A COMPLETE discussion of the literature on the subject of the influence of copper on iron and steel will be published elsewhere.1 The present paper is concerned especially with the precipitation-hardening of copper steels, and brief mention will be made here only of the work of Kin-near,2,3 Nehl4 and Buchholtz and Koster,5 who alone have studied this phase of the subject. Kinnear found that normalized low-carbon steel castings containing about 1.0 per cent copper on drawing at temperatures in the neighbor-hood of 530° C. (1000° F.) increased in tensile strength and yield point, with little decrease in ductility. The maximum effect was obtained with about 0.9 to 1.0 per cent copper, and when the copper exceeded 3 per. cent no improvement occurred on reheating. Kinnear did not study the effect of time of reheating-an all important factor where precipitation is concerned. Nehl,6 who apparently was unaware of Kinnear's work, recognized the change as due to precipitation and studied the interdependence of time and temperature of reheating, the temperature of the initial solution heat treatment, and the speed of cooling necessary to retain the bulk of the copper in supersaturated solu-tion and to give an increase in hardness and tensile strength on reheating. Nehl found that if the final rolling or forging temperatures exceeded 700° C. (1300° F.) it was not necessary even to normalize the steel, but full precipitation occurred on merely reheating the forged or rolled shapes at 500° C. (930° F.).

Jan 1, 1933

By F. L. Clerc

The lead and zinc region of SW. Missouri is interesting, not only by reason of the value of its output, which ranges in the neighborhood of ten million dollars a year, but even more because of the facilities which it offers for the study of certain forms of ore-deposits, of' which the loci and genesis are somewhat obscure. Although the mineral species found in the region are few and of common occurrence, crystallization has taken place on a generous scale, and unusual forms abound in many combinations, presenting examples of pseudomorphism, para-genesis, metasomatic replacement and the action of mineral-depositing and mineral-dissolving waters. For the mineralogist, lithologist, and specialist in certain lines of metamorphism, it has peculiar attractions, while the systematic geologist will perhaps find its chief claim to attention in the simplified problem it presents, in the study of ore-deposits. In addition to the phenomena above enumerated, it presents instances of well-developed comb-structure in the ores, fissures and faults, and slickensides—features usually associated with extensive movements in the earth's crust, and believed by some authorities to prove the deep-seated origin of the ores. In connection with these occurrences, the absence of all igneous rocks from this region is noteworthy and significant. For that reason, the simplified case presented by the Joplin region, from which these rocks have been eliminated as a factor, is specially valuable. Having had unusual opportunities to watch the development of this district, I have been deeply interested in the bearing of the revelations of the Joplin mines upon questions of universal importance to the science of ore-deposits; and it was to my great regret that the project of a meeting of the American Institute of Mining Engineers at Joplin, proposed in 1892, was

Jan 1, 1908

By G. L. Oldright, Virgil Miller

It is well known, in metallurgical circles, though less recognized in the technical press, that there have been remarkable increases in the capacity of the blast furnace in the last five .years. In places this capacity has been almost doubled. This paper will brief the experimental work carried on during more than five years with the direct assistance of the technical staffs of three lead smelters treating three distinctive types of feed. The first is the custom smelter of the International Smelting and Refining Co. at Tooele, Utah1, with a multiplicity of ores; the second, the Kellogg, Idaho, smelter of the Bunker Hill and Sullivan Mining and Concentrating CO.2, treating an exceedingly rich lead charge, such as is now being made more and more as the practice of concentration is improved; and the third, the smelter at Trail, B. C., owned by the Consolidated Mining and Smelting Company of Canada, Limited3, which treats highly zinciferous charges and later recovers zinc from the slag. In comparing operations at these three smelters it must be clearly recognized that the objectives in smelting differ through differences in economics. Many operations are not, then, strictly comparable. There have also been decided improvements in operation since all of the smelters were examined, though this was but a relatively short time ago. The general factors that govern speed in smelting and the loss of metals in the smelters examined will be stressed. (For details of operation the reader is referred to the original papers.) This paper will then be an examination of the fundamentals of operating units in a search for improvements, and not a description of three great lead smelters. Capacity of Blast Furnace Assuming a well prepared and self-fluxing charge to start with, enough coke must be added: (1) to melt the charge, particularly the slag-forming

Jan 1, 1937

By W. M. Weigel

WHILE electric lamps both of the cap and hand type are being introduced into many mines requiring the use of safety lamps, the oil-burning safety lamp is still used in the great majority of cases, and even where the former are used the latter must continue to be employed when testing for gas. It is not the intention to discuss here the relative merits of the two types, but simply to give a comparison of the illuminating effect or candlepower of several kinds of ordinary safety lamps used for general work and for testing. Few data have been published in recent years on this subject and because of this it is hoped that the following information may be of some interest and value. The lamps tested were in all cases. of standard size and in good condition, all practically new, and were selected from a collection of about 100 with a view to obtaining results on as many different common types as possible. With the exception of the gasoline-burning lamps, five different oils were used in each lamp to determine whether -particular oils were suited to particular lamps and whether there was any great difference in the illuminating power of the different oils, or whether some oils would maintain their illuminating power better than others throughout a working period of 8 hr. No attempt was made to determine the amount or cost of oil burned by each lamp, but the condition of the lamp, wick, glass, and gauzes was noted after each test.

Jan 8, 1916

By Tran K. Van, Francois E. Heuzé, Richard E. Goodman

Sound design of structures founded in or upon rock requires that the deformability of each rock member involved be characterized. This can be done by means of loading tests (plate bearing, flat jacks, borehole jacks, pressure chambers, etc.) or through convergence measurements (tunnel convergence, roof sag, etc.) in exploratory works. Analysis of data will be qualitative (degree of nonlinearity, creep behavior, scattering of results over a number of sites, etc.) and quantitative (modulus of elasticity or deformation). Some of these tests involve a very bulky apparatus and are expensive to perform. On the other hand, for the purpose of mapping and describing the various rock members which occur within a given site, many feet of diamond drill holes are frequently completed. Even with the optimum equipment and expert drillers, however, quantitative characterization of the rock units on the basis of tests on returned samples is apt to be misleading; the softer and weaker components of the rock tend to be lost and the fabric of the rock block- fracture system in situ is not sampled. Laboratory moduli of elasticity have proved to be consistently higher than in-situ values selected for engineering purposes. This led to the design of instruments which would operate in boreholes, combining the advantages of a reduced size and a deeper investigation, from the surface to several tens of feet. BOREHOLE DEFORMABILITY MEASURING INSTRUMENTS In the last 10 to 15 years, a number of testing devices have been con- structed which can be inserted into a borehole to apply a load and mea-

Jan 1, 1972

By E. E. White

In August, 1911, I read a paper before the Lake Superior Mining Institute1 on surveying and sampling diamond-drill holes. The present paper gives a more thorough descriptiou of these methods, together with a few changes and notes suggested by further experience. Since August, 1911, the methods, used constantly by the Cleveland-Cliffs Iron Co., have been developed to a higher degree of efficiency, and have given great satisfaction. Until a few years ago but little attention was paid to the determination of the actual course of drill-holes, to the accurate sampling' and analysis of the material, or to the scientific location of the drill-holes. It has now been common practice for several years in many districts to test the inclination of drillholes by etching glass tubes with hydrofluoric acid, but the direction of deviation from the vertical has not often been determined. Methods of determining the direction by means of a compass were first developed in connection with drilling in Victoria. The latest method used on the Rand in South Africa has been recently described by John I. Hoffman.2 In the same paper Mr. Hoffman describes an ingenious method of wedging-off a drill-hole so as to start new holes at several successive points. By this means a hole can be deflected in any desired direction, and the curvature can be controlled to a considerable extent, provided the rock is soft enough to permit the hole to be wedged off. Unfortunately, in the Lake Superior district, the jasper iron-formation is so hard that it is very difficult, if not impossible, to do this. I tried to deflect one hole so as to avoid drill-rods stuck in the hole, by using a

Jan 1, 1913

NEW MEMBERS The following list comprises the names of those persons who became members during the period Nov. 10, 1916 to Dec.10, 1916. BARNSDALL, THEODORE N., Treas. & Mgr., Highland Gas Co., 24 West Corydon. St., Bradford, Pa. BEASLEY, FRED E., Asst. Supt., Copper Refinery, Consolidated Mining & Smelting Co., Trail, B. C., Canada., BREWSTER, THOMAS T., Vice Pres., Gen. Mgr., Mt. Olive & Staunton Coal CO., 1012 Federal Reserve Bldg.,-St. Louis, Mo. BRINDLE ARTHUR ST. C.... Mining Recorder's Office, Trout Lake, B. C., Canada. BULLOCK, Harry E., Pres Kentucky-Jewel Coal Co., Lothair, Ky. BUTLER, PERCY BENNETT, Mine Operator :..P. 0. Box 335, Joplin, Mo. BUTLER, ROBERT S Supt., Three Johns Mining CO., ,Joplin,.Mo. CABOT, Godfrey, L., Carbon Black Maker, Gas Engr., 940 Old South Building Boston Mass.

Jan 1, 1917

By H. M. Chance

The Choctaw coal-field is a direct westward extension of the Arkansas coal-field, but its coals are not like Arkansas coals, except in the country immediately adjoining the Arkansas line. From the base of the coal-bearing rocks up to the top of the coalmeasures, I find a total thickness of at least 8500 feet. This great mass of coal-bearing rocks consists of an alternation of slates, shales, sandstones and coal-beds, with their accompanying under-beds of fire-clay. Only one small bed of limestone was observed. This occurs near the middle of the series; it is about eighteen inches thick, and quite arenaceous. The formation is naturally subdivided by seven or eight thick beds of sandstone, varying from 50 to 200 feet in thickness, the outcropping edges of which form a series of more or less bold " hogback " ridges, the interbedded shales and slate forming the intervening valleys. The base of the coal-series is a massive sandstone, ranging from 100 to 200 feet or more in thickness, lying immediately beneath the Grady coal-bed, which is the lowest known coal. In the district embraced between. the Missouri, Kansas and Texas railroad and the Arkansas State line, this sand-rock usually forms a bold semi-mountainous ridge. This is the ridge through which the St. Louis and San Francisco railroad passes at Bryan station, where the Grady coal-bed is opened and worked, from which point it can be traced westward without difficulty, passing about three miles north of Le Flor on the same railroad, thence west to the " Little Narrows " (which is merely a gap in the ridge), 'and beyond to a point two miles west of the Thompson-McKinney place, where it swings abruptly north for a mile or more, only to resume immediately its westward course, forming for some miles the northern boundary of the valley known as the " Boiling-Springs Prairie," beyond which it trends somewhat

Jan 1, 1890

By J. H. Fletcher

AIR has been cooled, heated, washed; humidified and dehumidified for many purposes and in many industries. At a number of metal mines air is conditioned to reduce the high humidity and unbearable heat found in deep workings, and at some mines air is washed to allay siliceous dust. Steam is introduced into the intake air at many coal mines, particularly in winter, for the purpose of keeping loose coal dust so moistened that the hazard of an explosion is lessened. This paper will describe a further successful application of air conditioning in a coal mine, where, for over three years, all intake air has been cooled to a constant temperature for the sole purpose of preventing roof falls.

Jan 1, 1931

By W. B. Daly, A. S. Richardson

The application of artificial refrigeration, or air-conditioning, to the ventilation of deep, hot mines has long been a subject of interest to the operators of such properties. Artificial cooling of the air in theaters, railroad coaches, and various industrial plants has been so successful within recent years that it has been natural to assume that the adoption of similar methods would afford a ready solution to the difficult problem of mine ventilation. It should however, be obvious, that although there may be nothing technically impossible in the application of this process to mine ventilation there is a great economic distinction between the maintenance of a high standard of comfort for a large number of people in a relatively small space such as a theater and the cooling of air to improve working conditions for miners scattered throughout the extensive workings of a large mine. Many methods of air-conditioning have been considered by the management of the Anaconda Copper Mining Co. at various times, but until the development of the process to be described in this paper none has seemed economically practicable. The Ventilating Problem at Butte The main obstacle to satisfactory ventilation in the Butte mines is the normally high temperature of the granite country rock. In the present operating zone, rock temperatures as high as 120' F. have been noted, and in some parts of the district the rate of increase of temperature with depth has ranged as high as 3.5" F. per 100 ft. Other factors, such as the decay of mine timber and the oxidation of sulfide minerals in the ore bodies, contribute to raise the temperature of the air in the working places but, particularly in the development of the mines to greater depth, the naturally high temperature of the rock is of predominant importance. In few other places, probably, are the ordinary ventilating measures more hindered than at Butte. At an operating depth now exceeding 3000 ft., all of the air required for ventilation must pass through timbered shafts which, because of heavy ground, are of small size and offer great resistance to the flow of air. Shaft compartments are rarely more than 4.5 X 5 ft., and the shaft area open to the flow of air usually does not exceed 65 sq. ft.; in only two shafts is the area as great as 85 sq. feet.

Jan 1, 1934