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By W. H. Bassett

BERYLLIUM was discovered in 1798 by Vauquelin and the metal was first produced by Wohler in 1828 about a year later than his production of metallic aluminum. Beryllium remained dormant until about 1920 when the production of the metal by the electrolysis of a molten bath was carried out by Stock in Germany, closely followed by Dickinson in the United States and by Vivian in England. This may not have been the first time the electrolytic method was thus used but was the beginning of present-day methods. I believe the first commercial attempts in this country started with the Kemet Laboratories about 1924. Siemens & Halske in Germany were working on the same problem at about the same time. The work of the Kemet Laboratories was transferred to the Beryllium Company of America and later to the Beryllium Development Corporation. In 1926 1 made a considerable study of the beryllium¬copper alloys, using beryllium purchased from the Beryllium Company of America, and read a paper on this subject at the February, 1927, meeting of the A.I.M.E. However, I failed at that time to discover the properties of precipitation hardening which such alloys have in a very marked degree. After this publication the work on beryllium-copper alloys rested awhile. One cause for this was the difficulty of securing a supply of beryllium-at least at what might be considered a reasonable price. In 1926 the price was $200 per lb., a figure which held about the same both in this country and in Germany until the beginning of 1932, when it was offered here at $50 per lb. if taken in the form of a copper alloy which carried about 121/2 per cent beryllium. Somewhat later the 121/2 per cent alloy dropped to $25 per lb. of beryllium contained, which is the present price. Promise is made that with a greater consumption, production on a larger scale warrants a reduction in price to $10 per pound or less.

Jan 1, 1933

By W. D. Robertson, D. A. Koss, A. J. Goldman

THE significance of the hcp (E) structure, which appears when Fe-Cr-Ni alloys (stainless steels) are transformed martensitically, has been the subject of considerable study and speculation.'-7 It has been proposed that the hcp structure is an intermediate phase in the transformation: fcc (austenite) — hcp (E) -bcc (0, martensite). However, recent studies by transmission electron microscopy6,7 have indicated that the hcp structure may be a consequence of the large shear strain (10 deg) associated with the fcc to bcc transformation. That is, the transformation to a bcc structure is accompanied by extensive dissociation of dislocations in the parent austenite, which has a low stacking-fault energy.'-'' X-ray diffraction analysis of the transformed alloy reveals a pattern of lines corresponding to an hcp structure, together with the parent austenite and the bcc product. The fact that the hcp structure is observed only in association with the bcc product in these alloys1'4'6'7 lends support to the conclusion that the hcp structure is a secondary product of the transformation. But, the evidence is circumstantial and more definite resolution of the two possibilities mains to be obtained. If the hcp structure is an intermediate product of the transformation, as in 1) above, then two distinct Ms temperatures should be observed, Ms and To evaluate this possibility, three different techniques that are particularly sensitive to the structural changes accompanying such transformations have been used in an attempt to detect two transformation temperatures in an Fe-15.1 Cr-11.7 Ni alloy: 1) high-sensitivity differential thermal analysis, 2) the temperature dependence of resonant frequency (elastic moduli), and 3) internal friction of cylindrical specimens vibrating in either longitudinal or torsional modes. To obtain the necessary sensitivity, a differential thermal analysis technique was developed for the purpose, Fig. 1. The differential temperature between a nickel standard and the specimen was amplified to produce a sensitivity of 0.02OC (0.7 v) in temperature difference. The specimen and the standard were surrounded by a copper block and the entire assembly was immersed in a solution of methyl and ethyl alcohol, freezing point, - 140OC, which provided the necessary thermal stability to reduce temperature fluctuations to negligible proportions. A cooling rate of about 1.5OC per min was obtained by bubbling liquid nitrogen through the liquid bath. In order to calibrate the experiment with respect to the evolution of heat in the transformation from fcc to hcp structures, differential cooling curves were obtained for an Fe-19.8 Mn alloy, which transforms martensitically to E.'"-' a Ms(e) temperature of 145°C was clearly defined by a temperature

Jan 1, 1964

By F. B. Plummer

THE physical properties of oil-producing sands, such as grain size, porosity, and permeability, are becoming more and more important in petroleum production engineering as oil fields are being repressured and rejuvenated. A number of excellent papers have been published recently on all three of these properties. Faucher, Lewis and Barnes1 give a com-plete survey of the work done through 1932 and contribute also much information on sands that they themselves have examined. Muskat and Botset,2 Wykoff, Botset, Muskat and Reed,3 Hurst,4 and Muskat5 have contributed a great deal to the theory and actual measurement of flow of liquids and gases through porous media. Muskat and Botset have measured the permeabilities of different sands with gases and liquids. They find that the radial is always slightly under the linear permeability. However, in most of the previous experiments small samples of the sand were used, and the method of production of fluid or gas through the sands has not been very close to actual oil-field conditions. In addition, so far as the authors are aware, no measurements of linear and radial permeabilities have been made simultaneously under exactly the same conditions. The multiple permeability apparatus described here is a part of the equipment being acquired by this laboratory for thorough investigation of the physical properties of producing sands. It possesses certain advantages for comparative studies of liquid flow. Additional data and descriptions of other instruments will follow in papers to be written later on. The essential features of the permeability apparatus are as follows:

Jan 1, 1934

By M. E. Lombardi

ThE Coalinga oil field is located on the west side of the San Joaquin Valley, California. The structure is in general a monocline, the edges of the oil horizon resting on the foot hills and dipping gently toward the east. One prominent anticline occurs plunging southeast. The earlier drilling was done in the foot hills comparatively near the outcrop and the wells were shallow. The sands were followed eastward and, in the case of the anticline, along the plunge, the wells becoming deeper and deeper until the depth of 4,000 ft. was reached and passed. There is nothing to show that the oil will not be found in quantity at still greater depth. In fact, some of the best producers have tapped the sand at close to 4,000 ft. The recovery of oil still farther to the east, and therefore at greater depth, seems to be mainly a question of drilling. In this territory the formations drilled through are chiefly sands and shales; they will not "stand up" in an open drilling hole; the casing has to be carried close to the bit, and it is always difficult to keep the casing free for any considerable distance. Ability to carry casing of comparatively large diameter without conductor pipes for distances of 2,000 or 3,000 ft. or over is desirable in such territory chiefly for two reasons. It makes it possible to enter the oil sand with a pipe of ample diameter; it eliminates one or more expensive strings of casing which act only as conductors for the water string, and furthermore, in territory where waters are encountered which corrode steel rapidly, it makes possible the construction of a rust- and alkali-resisting water string. It is always desirable to shut off top waters, which may lie within 100 ft. or less of the oil sand, with 10-in. pipe. Where the depth is so great that a practical weight of 10-in. pipe will not withstand the probable collapsing pressures, 81/4 in. at least is desirable. About the limit of rotary drilling to date in California seems to be the setting of the 10-in. string at 3,200 ft., although the rapid advance in rotary work during the past year seems to indicate that this depth may soon be increased. It is my purpose now, however, to treat only of cable-tool drilling. The problem is to reach a depth of 4,000 ft. or more with a string of

Jan 1, 1915

By Warden A. Moller

(Pittsburg Meeting, March, 1910.) THE Fushun coal-field, now being opened up by the South Manchurian Railway Co., is connected with the main line by a branch, 30 miles long, from Sui Chia Tun, 10 miles south of Mukden, the capital of Manchuria. The coal-field, which lies on the southern bank of the Hun river, 25 miles east of Mukden, consists of a long narrow valley,. running east and west between hills composed of granitic and volcanic rocks. At the foot of the northern hills, the Hun river flows westward towards the Liao river, which drains the greater part of South Manchuria. At the foot of the southern hills, resting immediately upon volcanic rocks, and overlain by 20 ft. of alluvial, is a thick layer of Tertiary shales, carrying near the base two coal-seams. In many places the lower of these two seams is in immediate contact with volcanic lauds and basalts, the flows of which were evidently both prior and subsequent to the formation of the coal-seams. This contact has practically destroyed the lower seam for commercial purposes. The value of the field lies in the upper seam, which, for a length of nearly 8 miles, varies from 100 to 130 ft. thick. Of this seam, 85 per cent is good coal. The seam dips to the north conformably with the shales, at angles of from 25° to 30°, and appears to have an uninterrupted dip for about 1.5 miles before being possibly cut o$' by the northern hills. The coal-bearing shales extend east and west for a length of about 20 miles, but towards the east the continuity of the seams is broken by intrusive rocks. The coal is of the sub-bituminous variety, low in ash, bright in appearance, and breaks with a conchoidal fracture. It has the usual qualities of Tertiary coal-quick steam-raising and poor stacking-qualities. Pieces of resin, varying in size from

Apr 1, 1910

PRESIDENT GEORGE OTIS SMITH, District 4 WASHINGTON, D. C. PAST PRESIDENTS SAMUEL A. TAYLOR, District 3 PITTSBURGH, PA. E. DEGOLYER District 0 NEW YORK, N. Y. FIRST VICE-PRESIDENT W. H. BASSETT District 1 WATERBURY, CONN. TREASURER KARL FILERS NEW YORK, N. Y.¬ SECRETARY H. FOSTER BAIN NEW YORK, N. Y.

Jan 1, 1923

By R. C. Hall

We are pleased to confirm some of the mechanical data presented by Dr. Detert on the 18 pct Ni marag-ing steel.15 Bar 3 in. in diam and containing 0.02 wt pct C, 18.5 Ni, 8.9 Co, 5.1 MO, 0.55 Ti, 0.05 Al, and balance iron has been examined in our laboratory. Cylinders 0.5 in. high and 0.4 to 0.5 in. in diam were cold-compressed from 3 to 40 pct reduction in height. Table VI shows some typical data; deformation in-

Jan 1, 1968

By AIME AIME

BEFORE proceeding with the papers scheduled for the ore and foundry session*, the teller's report on the election of officers for the ensuing year was presented, a; follows: Chairman. G.C. F. MacKenzie; vice-chairmen, C.S. Robinson, J. T. MacKenzzie, C. E. Meissner; executive committee, A. L. Field, R. F. Harrington, E. F. Kenney lit. Waterhouse announced that the fall meeting will be devoted to alloy steel. This meeting will be held in Chicago the week of Sept. 22 in connection with the National Metal Congress. He also announced that oxygen in steel will be the central idea of the meeting which will be held in New York next February. The first paper, entitled "Sintering Limonitic Iron Ore at Ironton, Minn.," was presented by Perry G. Harrison (T. P. 284), the author. Sintering was first un¬dertaken in 1024 to treat Cuyuna range iron and manganiferous ores low in silica and high in moisture and containing objectionable qualities of fine... A Dwight-Lloyd machine was first installed. This machine was replaced by a larger one having a width of 72 in. The power cost was decreased from about $11.22 per ton of sinter on a 42-in. machine to about X0.14 for the 72-in. machine. The tons of sinter per man-shift was increased from 11.86 to 16.77. Improvements embodied in the larger plant reduced the cost of sintering to $0.41. The analyses of iron ore and manganiferous ore and the sinter produced from these materials was used to show the increase in value at the mine resulting from sintering. Crude iron ore actually unsalable was increased in value f.o.b. mine from a theoretical figure

Jan 1, 1930

By Walter Hull Aldridge

Much has been said about the foreseeable exhaustion of known mineral reserves-particularly in the United States. It is claimed that we are about to become a have-not nation insofar as certain essential minerals are concerned; and in this respect our position is often contrasted with that of the world as a whole, largely because we have drawn so heavily on our domestic resources during the last fifty years. As a matter of fact, the difference is not great if one takes a reasonably long-term view of the situation. No one denies that nature endowed the United States richer in mineral resources than any other equal area. It is granted that we have skimmed the cream of many kinds of minerals; but in a free international trade in minerals it would not be many decades before the richer deposits-at least the deposits easy of discovery throughout the world would be depleted to much the same degree as those in the United States today. For it is a fact that the problem of satisfying the needs of our industrial society for minerals is fundamentally worldwide in scope. The singular and significant attribute to all minerals is that there is but a single crop. Forests can be grown, but mineral deposits can be replaced only by finding new ones. Thus, one of the vital tasks of the mining engineer, the petroleum engineer, and the geologist is to find these new mineral resources. Another task is to devise means and methods for the exploitation of, at costs that are economic, low-grade deposits and those deeply buried in the crust of the earth. The first need, however, is to find the deposits in the ground. If the assumptions of those who today fear an early exhaustion of all deposits are valid, the outlook for continued material and social progress is gloomy indeed. I take a more optimistic view, for it is my belief that vast new sources of needed minerals will have come to light before our known resources are gone. The real question is whether the outside layer of the crust of the earth that is accessible to engineers contains adequate mineral deposits; and whether engineers can find those deposits. The answer must be based on geologic science, geologic fact, and mining history. Every continent, and almost every country, has yielded minerals of industrial utility in substantial quantity. Mineral deposits are widespread. Geologists know the conditions that were favorable to the occurrence of ores and the types of rocks in which various kinds of ores may ordinarily be found. They know that such rocks occur over broad regions of the earth's surface. They also know that in large areas rocks that are potential carriers of ores are covered and concealed by material of entirely different character. Such cover may consist of lava flows, layers of volcanic ash, or beds of material washed down from the surrounding mountains. Sometimes those covers are thick, sometimes relatively thin. But men well-qualified to pass judgment are sure that concealed deposits, large in number and in size, exist close enough to the surface to make exploitation practical. Only by actual penetration of the surface can this contention be proved, but to conclude otherwise would be to ignore the laws of probability and to deny the over-all consistency of nature. The task of probing the crust of the earth to determine the location of these deposits, and to obtain some notion of their size and quality, poses serious problems. However, they should not be beyond human solution. Much more research must be done in analyzing and explaining the laws of ore deposition. New tools, in the shape of techniques and methods and of mechanical and electrical devices and instruments, must be developed. But no reasonable person can doubt that these objectives will be achieved. As the need becomes increasingly pressing, scientists and engineers will supply the imagination and the ingenuity that will provide the solution. The time and effort thus far devoted to the development of methods for locating hidden ore bodies have been pitifully meager. Energetic investigation of the subject of applied geophysics is essential to the success of the mineral industry, and I have no hesitation in predicting that effective techniques will be found and successfully applied. Twenty-five years ago the petroleum industry

Jan 3, 1950

By K. Shoji, R. Hogg, L. G. Austin

The flow of dry powders through continuous ball mills has been investigated. Based on a physical model of the system, expressions have been derived which relate the holdup of material in the mill and its variation along the length of the mill to the mill dimensions, speed of rotation, material feed rate, and the mill discharge geometry. Experimental results obtained in a small (4 in.) mill using 3/8-in. steel balls and a feed of silicon carbide particles are in good agreement with the prediction of the model.

Jan 1, 1976

By J. T. Norton, N. J. Grant, A. M. Gervais

An investigation of the creep deformation of coarse grained specimens of high purity aluminum in the temperature range 800' to 1150°F, permitted the formulation of a theory explaining the formation of kink bands. The X-ray Laue back-reflection technique was used in conjunction with metallographic studies to determine the crystallographic elements involved in kinking and to measure the rotations of the bands. THAT metals deform by the formation of kink bands was first shown by Orowan1 in 1942. He manually compressed cadmium single-crystal wires, the basal planes of which were parallel to the wire axis and to the direction of compression. He found that kink bands formed quite suddenly. Similar experiments were performed by Hess and Barrett2 on zinc with a hydraulic testing machine to permit slower more careful compression. They observed that kink bands formed progressively with increasing compression. Recently Washburn and Parker3 observed the formation of kink bands in zinc single-crystal specimens during tension creep experiments. Each of these authors observed the formation of kink bands but did not make a complete analyses of the crystallographic relationships. In addition to these studies on hexagonal metals, extensive investigations of kink bands formed during deformation of aluminum in tension at room temperature have been reported. Two types of deformation bands have been observed during the deformation of aluminum at room temperature. These are: 1—kink bands: these exhibit a sharp curvature of the lattice along certain surfaces, and 2—bands formed by secondary slip along certain regions. As has already been shown by Honeycombe,4 it is important to point out the difference characterizing the two types of deformation bands. In the first case. for moderate deformation, only one system of slip planes normally is active; in the second case, however, two slip systems are active in the deformation bands. The latter have a rumpled surface because of the action of the two slip systems. In the present work only the first type of band was studied and to avoid any confusion the term kink band will be used exclusively in the discussion which follows. Honeycombe' observed that very narrow kink bands (width, 0.01 mm) formed along the (110) planes during the deformation of high purity aluminum at room temperature. He observed narrower ones in commercially pure aluminum and found also that their width decreased with decreasing temperatures. Chen and Mathewson5 reported the formation of kink bands during tensile testing of single crystals of high purity aluminum at room temperature and pointed out that some rotation occurred about a [211] direction. The influence of the bending moment on the formation of kink bands was illustrated by the experiments of Rohm and Kochendorferl0 who used a Polanyi apparatus to obtain pure shear during tensile testing of high purity aluminum single crystals. Under such conditions only one slip system was active and no kink bands were observed; consequently, no noticeable asterism was detected after deformation. The influence of the bending moment will be discussed later. Calnan8 gave a detailed account of the work performed on kink bands obtained during deformation of aluminum at room temperature. Because no explanation of the process of kink band formation in creep was given in the previous investigations and because some of the above observations are vital to the following discussion the brief review of the literature has been given. It is proposed in the present work to provide an explanation of kink band formation during creep deformation at elevated temperatures. Results and Discussion Kink bands were observed to form during tensile creep testing of high purity (99.995 pct) aluminum specimens, having a very large grain size, in the temperature range 800" to 1150°F. These observations were made in grains which occupied the whole cross section of the specimen. The specimens were originally round (diameter, 0.187 in.; gage length, 1 in.) and had parallel flats milled to permit easier metallographic and X-ray observations. The final

Jan 1, 1954

By J. Jolly, R. V. Wheeler

This short note on the probable character of the organic sulfur compounds in coal can do no more than indicate lines of research. We have no new experimental work to describe, nothing comparable in value with the careful studies of American coals by Powell and Parrl and Yancey and Frazer. A study of the manner in which sulfur compounds exist in British coals (and their behavior on heat treatment) is rendered increasingly necessary by the fact that the British reserves of good coking coals of reasonably low sulfur content are fast being depleted. We believe that it is essentially by a study of the modes of formation, occurrence, and decomposition of the various types of inorganic and organic sulfur compounds in coal that it will be possible, with hope of success, to attack the problem of purifying coals, otherwise eminently suitable for coking, from these objectionable ingredients. Sulfur, so far as is at present known, does not normally occur in the free state in the coal conglomerate, but is chiefly distributed, irregularly, in three forms : 1. As primary constituents of the coal conglomerate, organic in nature and probably associated with those molecular complexes that have resulted from the degradation of the proteins of the plant tissues responsible for the formation of the coal mass. These constituents can be classed as "organic sulfur." 2. As metallic sulfides, e.g., iron pyrites. 3. As metallic sulfates, e.g., calcium sulfate and ferrous sulfate. (The occurrence of these compounds varies with the occurrence and degree of degradation of class 2.) It is usually found that sulfur compounds of class 3, the metallic sulfates, are present in coal in small proportions only, amounting to about 1 or 1.5 per cent. of the total sulfur. The compounds in classes 1 and 2 are therefore of more importance. Class 1 alone will receive considera-

Jan 1, 1925

By F. X. Tartaron

This article is a continuation of a previous paper by the writer in which Kick's Law was stated to be a part of comminution theory. ln the present paper, a broadening of ideas is attempted in order to state a general theory. The word "general" is employed because the new theory includes all previous laws and generalizations which are considered to be essentially correct. These ideas are combined into a coherent whole and the general theory can be expressed by the equation In the author's previous paper on comminution, ' the equations developed were based on Charles' equation of exponents a-n +1 = 0. 2 This paper is divided into two parts, designated as First Approach and Second Approach. In the First Approach, the equations of the previous paper are utilized, with Charles' equation of exponents being necessary. In the Second Approach, a separate and independent method is used to derive the same conclusions as in the First Approach, but without the use of Charles' equation of exponents. Holmes accepts the theoretical foundation of Kick's Law as sound but denies that the law as such operates in comminution. His idea is that Kick's Law requires homogenous matter whereas the presence of cracks, flaws and cleavage planes, which predominate in the coarser particles, makes matter unhomogene-ous. This explains why there is no experimental evidence to support Kick's Law. However, since the basis of the law is theoretically sound, all experimental evidence must be viewed as emanating from it. This requires modification of current comminution equations to fit this concept. Holmes makes the modification by changing the constant exponent n in the general energy equation used by Charles (E = - JCdx/xn) to a variable exponent r. The writer asserts that Kick's Law operates in comminution without modification but it does not

Jan 1, 1963

By Philip D. Wilson

IT has been my privilege to read the article prepared by R. S. Dean entitled "Production of Alumina from Low-Grade Domestic Materials" which appears on another page of this issue. Dr. Dean should be congratulated on the preparation of such an erudite and scholarly dissertation on bauxite and on the work which the Bureau of Mines has been doing in connection with the development of processes to use low-grade domestic materials.

Jan 1, 1943

By M. Metzger, J. Intrater

IN the large number of important studies on high-purity aluminum (e.g., recrystallization and grain growth, creep, internal friction), it does not seem to have been generally recognized that the iron content, despite its very low figure, has a strong influence on a number of properties. In part, its influence is due to the very low solubility of the Fe-A1 6 phase. For aluminum of about 99.99 pct purity, the iron content may be 0.001 to 0.004 pct. For values in this range, a second phase will be present below 410" to 480 °C. This was determined by extrapolation of a log solubility vs inverse temperature plot of the solid solubility data of Edgar.' One consequence is the inhibition of grain coarsening below the solubility limit. This is shown in Table I, which gives, for three iron contents, the annealing temperature required for the absence of grains smaller than 1/2 mm average diameter together with the minimum temperature for the presence of some grains larger than 2 mm diameter. The specimens were 1/4x 1 1/2-in. strips cut from hard-rolled 1/16-in. sheet supplied by the Aluminum Co. of America.

Jan 1, 1954

By Philip B. Bucky

[ ] FOREWORD THIS symposium brings together points of view, experiences and ideas on rock bursts from a goodly portion of the globe. Some conceptions, particularly those regarding the necessity of depth, have been fairly well shattered, as we find that they are present in the water tunnels of New York, on the surface at marble quarries in Vermont, and in the coal mines of the United States, as well as in the deep mines of the South African and Kolar gold fields, and in the nickel, copper and gold mines of Canada. Their occurrence under such a variety of conditions is, therefore, a challenge,

Jan 1, 1942

By W. C. Williamson, J. L. Shugert

DUST control is receiving considerable attention today by most companies as is evidenced by the many articles, papers, and books written on the subject. ~~~t of the larger mining companies have given this subject close study and have established standardized methods of control. W. C. WILLIAMSON and J. L. SHUGERT, Members AIME, are Assistant Ventilation Engineers, Anaconda Copper Mining Co., Butte, Mont. San Francisco Meeting, February 1949. TP 2705 A. Discussion of this paper (2 copies) may be sent to Transactions AIME before Feb. 28, 1950. Manuscript received Jan. 17, 1949. Permissible Limits: The question of permissible dust limits has been considered by medical commit-ties and various national conferences. Dr. Lanza, of the Metropolitan Life Insurance Company, Dr. Le-roy U. Gardner, of the Saranac Laboratory for the study of Tuberculosis, and Dr. Pancoast, of the University of Pennsylvania, have been members of these committees. A statement included in reports of some of these committees is as follows: Concentrations to which the dust must be induced in order to be safe have not been absolutely determined. There is evidence that a concentration of more than five million particles per cubic foot of a highly siliceous dust is dangerous. Therefore, it may be stated that it is desirable to avoid counts of more than five million particles of dust containing free silica to a high percent in working places. Table I gives the safe limits adopted by several state industrial codes. Table I. Safe Limits of Dust Concentration Limit Million Particles State Per Cu Ft Cal~fornia Silica (less rhdn 10 pct) 50 Silica (10 pct to 50 pcr) 10 Sllica (more than 50 pct) 5 New York Frcc silica less than 10 pet by weight of rock formation 100 Frec silica more than 10 Pct by weight of rock formation 10 Oregon Silica (over 40 pct) 5 Silica (20 to 40 pct) 10 Silica (10 to 20 pet) 20 Wisconsin 15 million particles, under 10 nicrons in longest dimension per cu ft of air, when the quartz content of the dust is 35 pct, variations in free silica content will make proportional inverse changer in this standard Close attention to dust concentrations has been given to mining operations, since these operations are frequently carried on at considerable distances

Jan 1, 1951

By J. L. Shugert, W. C. Williamson

DUST control is receiving considerable attention today by most companies as is evidenced by the many articles, papers, and books written on the subject. ~~~t of the larger mining companies have given this subject close study and have established standardized methods of control. W. C. WILLIAMSON and J. L. SHUGERT, Members AIME, are Assistant Ventilation Engineers, Anaconda Copper Mining Co., Butte, Mont. San Francisco Meeting, February 1949. TP 2705 A. Discussion of this paper (2 copies) may be sent to Transactions AIME before Feb. 28, 1950. Manuscript received Jan. 17, 1949. Permissible Limits: The question of permissible dust limits has been considered by medical commit-ties and various national conferences. Dr. Lanza, of the Metropolitan Life Insurance Company, Dr. Le-roy U. Gardner, of the Saranac Laboratory for the study of Tuberculosis, and Dr. Pancoast, of the University of Pennsylvania, have been members of these committees. A statement included in reports of some of these committees is as follows: Concentrations to which the dust must be induced in order to be safe have not been absolutely determined. There is evidence that a concentration of more than five million particles per cubic foot of a highly siliceous dust is dangerous. Therefore, it may be stated that it is desirable to avoid counts of more than five million particles of dust containing free silica to a high percent in working places. Table I gives the safe limits adopted by several state industrial codes. Table I. Safe Limits of Dust Concentration Limit Million Particles State Per Cu Ft Cal~fornia Silica (less rhdn 10 pct) 50 Silica (10 pct to 50 pcr) 10 Sllica (more than 50 pct) 5 New York Frcc silica less than 10 pet by weight of rock formation 100 Frec silica more than 10 Pct by weight of rock formation 10 Oregon Silica (over 40 pct) 5 Silica (20 to 40 pct) 10 Silica (10 to 20 pet) 20 Wisconsin 15 million particles, under 10 nicrons in longest dimension per cu ft of air, when the quartz content of the dust is 35 pct, variations in free silica content will make proportional inverse changer in this standard Close attention to dust concentrations has been given to mining operations, since these operations are frequently carried on at considerable distances

Jan 1, 1951

By C. S. Matthews, P. Hazebroek, H. Rainbow

It ha been suggested that lormation fractures created by well stimulation treatments will adversely affect sweep-out efficrency in injection operations. Fluid-flow model studies involving vertical fractures of various lengths and fluid systems of various mobility ratios have been carried out to study this subject. In addition, limited data have been obtained on one model containing a horizontal fracture. It was found that relatively long and highly conductive fractures (not generally obtained fracturing operations) were required to affect the sweep-out efficiency substantially. In a given case in the field an approximate distinction can be made between the presence of long conductive fractures and shorter or less conductive ones. This is done with pressure build-up analyses along with data on the relationship of fracture length and conductivity to well productivity. This type analysis shows that usually the fractures induced are either short or of limited conductivity and therefore do not damage sweep-out efficiency. INTRODUCTION Improved well productivity and in-jectivity can frequently be exploited in injection operations. Higher total throughput can yield improved economics. On occasion, the achievement of an increased productivity or injectivity in specific wells can bring about a more uniform sweep of the reservoir. Higher rates can be exploited particularly in water floods of "depleted" reservoirs where a rapid "fill-up" is desired and where low pressures contribute to low well productivity. The creation of fractures local to the wellbore is an excellent means for achieving these objectives. Even though fracturing has been employed in some floods with success,1"3 there still seems to be some reluctance to employ this tool for fear of undue damage to the flood pattern and ultimate recovery. We therefore need to examine the influence which fractures of varying length may have on flood performance and then determine the length of fractures which obtain in the field with conventional fracture treatments. A substantial influence of fractures on the recovery obtained at breakthrough of the injected fluid has been presented by Crawford and Collins for equal fluid mobilities for the line-drive pattern.4,5 In addition, the influence which a fracture has on the production performance after breakthrough and on the ultimate recovery warrants consideration in reaching a conclusion concerning the use of induced fractures in flooding operations. This report presents this type of data for the five-spot injection pattern for several fluid mobilities. In arriving at some conclusion concerning the fracture lengths obtained in field operations we must examine the performance characteristic most affected by the fracture. This is the change in the flow system as reflected in the change in productivity and pressure build-up behavior. A study of these changes is also presented in this report. RESERVOIR ANALOGS The X-ray shadowgraph technique, employing miscible displacement in porous models, has been used in the study of the influence of fractures on pattern sweep-out efficiency. The X-ray shadowgraph procedure is described in detail in an earlier report8. Fractures were represented by leaving the proper portion of the model surface exposed to either injection or production. This assumes the fracture resistance to be negligible compared to that of the formation. Actually the flow resistance in propped fractures obtained in the field is sometimes not negligible so that the results with this model indicate the maximum influence of the fracture. Two types of models were necessary to represent vertical fractures in a five-spot flood. These pattern elements are illustrated in Fig. 1. In studying the influence of the horizontal fracture, only one well spacing length to thickness ratio of 50 was used. The pool unit of a Carter Electric Analyzer was used in studying the influence of fractures on productivity and build-up behavior. The square drainage system of a well was represented by a network of 576 elements of equal volume and resistance. One-fourth of this drainage area was studied as a model unit using a network of 144 condensers and resistors. Vertical fractures were represented by a shunt directed from the well perpendicular to the drainage boundary. Horizontal fractures were represented by a circular shunt. Resistance of a shunt was varied in representing different conductivities for the fractures. FRACTURE DIRECTION AND LENGTH The direction at which a vertical fracture extends into the formation and its length and conductivity influence the sweep behavior. The two

By Ernest Burchard

FLUORSPAR is found in most of the states from the Rocky Mountains westward, and commercial production of the mineral has been reported from Arizona, Colorado, Nevada, New Mexico, Utah and Washington. The map in Fig. 1 indicates the general distribution of many of these deposits but it is by no means complete. In the summer of 1926 the writer examined certain deposits of fluor-spar in Arizona, California, Colorado, New Mexico and Washington; in November, 1927, revisited the Jamestown, Colo., district, and in earlier years examined deposits in Colorado and New Mexico. Based on notes of his own and. on descriptions and other data by H. A. Aurand, H. W. Davis, R. B. Ladoo, V. C. Heikes, W. D. Johnston, Jr., and by producers of fluorspar, he prepared the following brief descriptions of deposits and estimates of reserves of fluorspar, originally for the use of the subcommittee on fluorspar of the Joint Committee on Foreign and Domestic Mining Policy and on Industrial Preparedness respectively of the Mining and Metallurgical Society of America and the American Institute of Mining and Metallurgical Engineers. Descriptions of many fluorspar deposits in various western states and districts have been published. It is not feasible to summarize this literature here, but the appended bibliography will indicate to the interested reader what papers are available.

Jan 1, 1933