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By H. F. Yancy

PooR results in coal washing and in ore concentration are sometimes attributed to the shape of the particles in the feed. It is well known that the shape of a particle influences its rate of fall in water. This is evidenced by the value of the constant C in the Rittinger equation for the velocity V of settling in water, V = C-D(d- z ), where C has the following values: 2.73 for roundish grains, 2.37 for long grains and 1.92 for flat grains. This report, which is based upon data obtained during the course of coal-washing investigations conducted by the U. S. Bureau of Mines in cooperation with the College of Mines of the University of Washington, gives the results of a method or procedure of screening in which the particles are separated into three shapes and shows the deportment of these shapes when coal is treated on a coal-washing table. The method consisted in first screening the coal with Tyler standard square-hole sieves, followed by screening tests of each of these products with screens of rectangular opening. For this purpose Tyler "Ton-Cap" screens were used; each square-hole product was subsequently sized with two Ton-Cap sieves so selected that their shortest dimensions were approximately 75 and 50 per cent., respectively, of the opening of the square-mesh sieves. For example: A product which is through 8 mesh (0.093 in.) and on 10 mesh (0.065 in.) is screened on slotted sieves which have openings 75 and 50 per cent. of the 0.065-in. opening in one direction and an opening of not less than 0.065 in. in the other direction. For convenience in discussion, the particles retained on the first slotted screen are termed "cubical"; those retained on the second slotted screen are termed "prismatic" and those passing the second screen are called "flat." (See Fig. 1.) The square-mesh screens separate particles according to two dimensions, length and breadth; the slotted screens divide them further according to the third dimension, or thickness. Prismatic particles have a mass of about two-thirds, and flat particles of about one-half, that of cubical particles of the same square-mesh size. The screen-

Jan 1, 1931

By D. F. Kaufman, V. V. Damiano, G. J. London, L. R. Aronin

Beryllium bicrystals were Prepared by a seeding and floating zone-melting technique from high-purity beryllium single-crystal material. The starting material was given six floating zone purification passes prior to producing the bicrystals. Symmetric, asymmetric, and antisymmetric bicrystals were tested in tension. Included were bicrystals with boundaries both parallel and perpendicular to the tension axis. Modified symmetric bicrystals were also examined in detail. In these cases, the angles made by the slip planes with the boundary were not equal. Failure by (0001) cleavage, (1180) cleavage, and boundary separation were all observed depending on the orientation of these cleavage planes and the boundary with respect to the tension axis. Failure occurred on whichever system experienced the greatest normal stress. The origin of the fractures observed and the operative dislocation mechanisms were investigated by frac-tography and transmission electron microscopy. The results indicate that low-angle boundaries form in close proximity to the bicrystal boundary and act as sites for crack nucleation. It has been concluded that, although macroscopic compatibility was satisfied in many of the bicrystals examined, the bicrysta1 boundary was effective in Producing "early" failure by local bend plane formation as plastic deformation proceeded, followed by cleavage initiation and crack propagation. SINGLE crystals of high-purity beryllium oriented with the basal plane inclined 45 deg to the tension axis exhibit a critical resolved shear stress of about 300 psi and 200 pct extension by slipping only on the basal plane before failure by cleavage on that plane. Single crystals, oriented with the basal plane parallel to the tension axis, deform by prism slip at a critical resolved shear stress of 9000 psi and exhibit an extension of over 100 pct before failure in a ductile manner.' In contrast to the behavior of single crystals, poly-crystalline beryllium deformed in tension or bending exhibits little or no ductility at room temperature. Beryllium's lack of ductility at room temperature has been attributed to its lack of a sufficient number of independent slip systems. Beryllium has only four independent slip modes at room temperature and according to the Taylor2 and von Mises3 criteria at least five independent shear modes are necessary to completely satisfy the strain compatibility conditions at all the boundaries in a random polycrystalline sample. Studies of beryllium bicrystals thus appear to provide a convenient way in which to determine whether the condition of strain compatibility is a necessary and sufficient condition to prevent failure and whether obviously incompatible boundary conditions result in boundary separation. Bicrystal studies, although not providing all of the constraints encountered in polycrystalline samples, do allow one to select very specific orientation relation-

Jan 1, 1969

[Note.—The paper of Mr. W. H. Hoffman (Glen Summit, October, 1891; Trans. xx., 602), on "Practical Results in the Magnetic Concentration of Iron-ore," together with a paper by the same author (Baltimore, February, 1892; Trans. xxi., 126), on "Granulating Magnetic Iron-Ores with thesturtevant Mill atCroton Magnetic Iron-Mines, N. Y.," and also the papers Presented at this meeting,

Jan 1, 1893

MODERN mining is based on drilling--everything else stems from that. U. S. and Canadian mining companies and suppliers of mining equipment are constantly seeking new techniques and tools for increased drilling efficiency. Ultimate goal is increased bit-against-rock time. Just how important their efforts are can be seen through a legitimate extension of available statistics. In Canada some 70 million ft of drilling per year is required. While the number of feet actually drilled in the U. S. is unknown, it is possible to compare U. S. and Canadian mineral production, excluding oil and coal. In the U. S. mineral value was $4200 million and across the border $836 million. Taking into account the number of drilled feet required to produce Canada's total, the U. S. total would be 365 million ft in 1953. A saving of 14 per ft would reduce over- all metal and nonmetal mining costs some $3.65 million per year. This does not take into account other indirect savings. Methods have changed and there have been structural and metallurgical advances in blasthole practice in the last ten years. The Editors of MINING ENGINEERING in the articles on the following pages present the most significant innovations coupled with results in the field. Environment plays an important role in selection of materials and equipment -but while unanimity does not exist throughout the industry in reference to drilling problems, a definite trend is evident. For the story of that trend read the articles on the following pages.

Jan 9, 1954

By K. K. Clark

Excessive injection pressures in water injection wells may create deeply penetrating fractures, or may open up existing reservoir fractures. If these fractures are oriented toward offset producing wells, oil recovery at injected water breakthrough and ultimate recovery will be impaired. A method of calculating fracture lengths from pressure fall-off test data is presented. The method is based on a linear flow model that simulates conditions present during the early-time period after shutting in an injection well. Fracture lengths can be calculated directly if formation permeability is known. A graphical technique is presented that provides fracture lengths based on permeabilities calculated from normal fall-off tests, where those permeabilities are adjusted for flow geometry. Test data from four injection wells and results obtained from applying the method to these wells are discussed. Introduction Rates of water injection into nonstimulated wells in low permeability reservoirs frequently fall below economically desirable levels. Therefore, some form of stimulation such as hydraulic fracturing often is performed on these wells. Usually these fractures penetrate a short distance from the well — short as compared with interwell spacing — and therefore should not create problems of water channeling to offset producing wells. In the past, some operators have been tempted to increase injection pressures continually to maintain a specified injection rate. But pressures cannot be increased indefinitely. Field data indicate that continued injection above fracture opening pressure can cause excessively long fractures to approach between well distances. If these long fractures intersect or closely approach offset producing wells, premature water breakthrough can result. It is difficult to seal effectively these fractures by various workover procedures after premature water breakthrough has occurred. This paper describes testing procedures that are potentially capable of detecting premature water breakthrough before it occurs. Knowledge of fracture lengths and fracture opening pressures can assist field engineers in selecting optimum operating conditions for water injection wells. Fracture lengths should be calculated from pressure fall-off tests on injection wells, and maximum permissible iniection pressures should be determined from step-rate injectivity tests. Equipped with this information, the field engineer is in a better position to recommend for a particular injection well the optimum operating conditions that will lessen the chances of channeling to offset producers. Historically, pressure transient tests have been conducted primarily on producing wells and analysis procedures have been based on radial flow concepts. Several authors have suggested that these same procedures be applied to tests conducted on water injection wells. This application is justified for wells that are not connected to extensive fracture systems. However, if the formation is severely fractured, the interpretation methods must be modified. Several authors have presented the pressure response of various systems that are intended to simulate reservoir conditions. A paper by Russell and Truitt* on vertically fractured svstems is probablv the most useful from the standpoint bf the fieid engineer. Russell and Truitt presented the pressure-vs-time behavior of a well connected to vertical fractures with various fixed lengths. Their permeability adjustment technique is used in this paper to refine methods of calculating fracture length and interwell permeability. Theory and Definitions Three flow-system geometries are considered in analyzing injection well test data. These various geometries are applicable during specific time intervals of transient pressure tests. Schematic drawings of the flow models, and the time intervals over which they are applicable, are shown in Fig. 1 in the chronological order that they are applied to the pressure response of water injection wells in fractured formations. The very early response is simulated by an infinite linear system as shown in Fig. 1A. This representation permits the calculation of matrix surface area exposed to the fracture. The model shown in Fig. 1B is identical with the one studied by Russell and Truitt. They evaluated the transient pressure response of this vertically fractured system by finite difference techniques. The results were presented as tabulations of dimensionless pressure drop functions for a range of fracture lengths. A semilog plot of these data shows that the apparent matrix permeability can be related to the true matrix permeability by a simple exponential function. Their adjustment factor is used in this paper to improve the accuracy of matrix-permeability and fracture-length calculations.

Jan 1, 1969

By R. L. Vaughn, H. R. Cooper

Effective procedures for automating X-ray assaying by use of a computer are described. These methods have advanced the reliability and accuracy of X-ray data, resulting in improved assay measurements for operations and process control. Assaying by X-ray fluorescence has been increasingly used in the mining industry, both for analyzing solid H.R. COOPER and R.L. VAUGHN, Members AIME, are Systems Manager-Process Control and Senior Systems Analyst, respectively, Scientific & Engineering Computer Center, Ken-necott Copper Corp., Salt Lake City, Utah. TP 68B236. Manuscript, Sept. 16, 1968. Discussion of this paper, submitted in duplicate prior to Dec. 15, 1969, will appear in SME Transactions, March 1970, and AIME Transactions, 1970, Vol. 247. samples for smelter, mill, and mine quality control and for continuous stream analysis of mill pulps. The important advantages of X-ray methods in laboratory assaying are reduced analysis cost, and for on-stream analysis, immediate assay information on concentrator streams. Of the numerous reports concerning X-ray analysis in mining operations, one is referenced which can be noted particularly in conjunction with this report.' Continuous X-ray analyzers have been installed at Kennecott and other mining companies for operations guidance and trend information for a number of years. However, complete operational acceptance of X-ray data has been slow, due* to the difficulty in maintaining

Jan 1, 1970

By Hugh S. Spence

THE use of natural feldspathic rocks, as opposed to straight feldspar, for ceramic purposes is not new. "Cornwall stone," a semi-kaolinized granite containing fluorite, has long been used by the English pottery trade instead of feldspar, and "Carolina stone," a similar rock, is now being offered to the American trade. A recent report of the U. S. Bureau of Mines states that trachyte, a glassy volcanic rock, is being used in California instead of feldspar in ceramic bodies. In Germany, phonolite and basalt have been investigated, and possibly also used, as ceramic raw materials, and extensive research has been conducted in Russia in recent years looking to the utilization of the immense bodies of nepheline syenite of the Kola Peninsula, which is the host rock of the apatite deposits now being exploited on a large scale in the Murmansk region; the nepheline is recovered as a by-product of the concentration of the apatite. Long used principally as a raw material for the pottery and allied industries, where, in bodies, glazes, enamels, etc., it serves as a fluxing ingredient and forms, on firing, a glassy bond with the more refractory clay, flint and coloring particles, feldspar has been finding ever increasing employment in glass. In 1936, over half of the nearly quarter of a million tons of feldspar sold in the United States went to the glass trade. Its usefulness for this purpose is due to the resistance to thermal shock which it imparts to glass products, particularly bottles, containers and tableware, because of its alumina content, which averages from 16 to 20 per cent. Active search has been made on the American continent during the past few years for other minerals of feldspathoid type, with comparable or higher alumina content, that may be suitable for glass and other ceramic purposes. One of the most important results of this work has been the delimiting in central Ontario of large bodies of nepheline syenite of excellent ceramic grade.

Jan 1, 1938

By J. David Lowell

For the first time in several years, Chile is again opening its doors to foreign investment. In its new investment code, the Chilean government has announced its willingness to become a partner in joint Chilean-foreign projects for a number of government-controlled porphyry copper deposits at the developed, semi-developed, or prospect stage; and, that it will allow privately owned deposits or deposits discovered by new exploration to be developed with up to 100% foreign ownership. Three deposits of particular interest are: El Abra, with at least 300 million mt of +100% Cu; Los Pelambres, with at least 428 million mt of 0.78% Cu and 0.03% Mo; and Andacollo, with 350 million mt of 0.70% Cu and 0.015% Mo. (El Abra is almost entirely government- controlled; but both Los Pelambres and Andacollo are mostly under private ownership.)

Jan 11, 1974

By RUSSELL C. FLEMING

THE important advances that have been made of recent years in mining and milling methods and in mechanical equipment at mines need no re- telling, but there has been a remarkable growth in one type of equipment which has gone nearly unnoticed. That is the increasing use of storage-battery locomotives underground. Since the war the number of these locomotives and their field of use have increased tremendously; their growing acceptance represents an al- most complete reversal of opinion from an earlier period when they were generally looked upon as in- adequate for the strain of mine service. At the time when storage-battery powered units were first making their bid for recognition, the use of power in haulage had already passed through several phases; hand tramming, rope haulage, compressed air locomotives, even gasoline locomotives, had all been used, ending finally in the general adoption of the electric trolley locomotive for practically all power-haulage requirements. It was, and is, conceded that the trolley loco- motive met more adequately the varied and severe conditions of mine service than any previous type of haul- age unit. Subsequent developments have had to endure comparison and surpass in performance that type of haulage before changes would be considered.

Jan 1, 1930

By Donald E. Ackerman, Norman B. Pilling

The solubilities of a series of experimental alloys covering the range 0 to 100 per cent. Ni, 0 to 30 per cent. Cr have been studied under conditions of complete submersion in several fully aerated acid solutions, and in solutions containing sulfurous acid. In nonoxidizing, hydrogen-discharging acids, if the nickel content is below a certain critical amount, chromium increases the rate of solution and nickel decreases this rate; this critical content of nickel is about 13 per cent. Alloys containing more than this corrode at a constant minimum rate independent of iron, nickel or chromium contents. Austenitic chrome-nickel steels may thus have a resistance to these acids equal to that of nickel-chromium alloys. In nitric acid and in unaerated sulfurous acid rather sharp limits of attack occur which are principally dependent on chromium content. In the former the limit of attack is not related to a particular chromium content but varies continuously with acid concentration. The action of sulfurous acid on these alloys is highly dependent on the presence of small amounts of other substances in solution, and many sulfurous acid mixtures rapidly attack alloys to which the pure acid is wholly inert. The observed effects are not compatible with Tammann's theory relating corrosion resistance to lattice structure but are believed to be concordant with current views of the electrochemical nature of corrosion. Introduction The discovery, development and engineering application of iron alloys resistant to corrosion may well claim a place among the important developments in metallurgy of the past two decades. The varied demands of industry coupled with the skill of the metallurgist have resulted in the production of an extensive group of steels and alloys ranging from the now familiar "stainless " chromium steels of the kitchen to special alloys of great chemical complexity for particular, exacting needs. Any adequate description of the important properties of these-— physical, chemical and economic—would be a formidable undertaking.

Jan 1, 1929

By Donald E. Ackerman, Norman B. Pilling

The solubilities of a series of experimental alloys covering the range 0 to 100 per cent. Ni, 0 to 30 per cent. Cr have been studied under conditions of complete submersion in several fully aerated acid solutions, and in solutions containing sulfurous acid. In nonoxidizing, hydrogen-discharging acids, if the nickel content is below a certain critical amount, chromium increases the rate of solution and nickel decreases this rate; this critical content of nickel is about 13 per cent. Alloys containing more than this corrode at a constant minimum rate independent of iron, nickel or chromium contents. Austenitic chrome-nickel steels may thus have a resistance to these acids equal to that of nickel-chromium alloys. In nitric acid and in unaerated sulfurous acid rather sharp limits of attack occur which are principally dependent on chromium content. In the former the limit of attack is not related to a particular chromium content but varies continuously with acid concentration. The action of sulfurous acid on these alloys is highly dependent on the presence of small amounts of other substances in solution, and many sulfurous acid mixtures rapidly attack alloys to which the pure acid is wholly inert. The observed effects are not compatible with Tammann's theory relating corrosion resistance to lattice structure but are believed to be concordant with current views of the electrochemical nature of corrosion. Introduction The discovery, development and engineering application of iron alloys resistant to corrosion may well claim a place among the important developments in metallurgy of the past two decades. The varied demands of industry coupled with the skill of the metallurgist have resulted in the production of an extensive group of steels and alloys ranging from the now familiar "stainless " chromium steels of the kitchen to special alloys of great chemical complexity for particular, exacting needs. Any adequate description of the important properties of these-— physical, chemical and economic—would be a formidable undertaking.

Jan 1, 1929

By Earl G. Alexander, W. R. Runyan

The nature of silicon growths which form on amorphous silicon dioxide during epitaxial deposition in unmasked areas was investigated. Octahedral silicon crystals nucleate and grow on the oxide at pinholes, adjacent to foreign matter, and probably at oxygen-deficient sites. Generation of these oxygen-deficient sites on the oxide surface is shown to be thermody-namically favorable under usual deposition conditions. The conditions which affect saturation (SiCl4 concentration, flow rate, temperature) determine the number of sites on which silicon will nucleate and grow. Reaction product HCl is likely responsible for suppressing silicon growths on the oxide near exposed areas of silicon. Evidence is given that the oxide-silicon interaction occurs in hydrogen only and involves water as a transport agent. SINCE shortly after the first epitaxial layers of silicon and germanium were grown over large areas, efforts have been underway to grow selectively on specified portions of the surface. Such selective growth should be particularly applicable to monolithic integrated circuits. Usually the approach has been to use a mask to delineate the desired area,'-7 but the VLS methoda can also be used, and direct programmed atomic beam deposition has been suggested.9 The masking techniques may embody two forms: in one the mask is a material which can later be removed along with any growths attached to it; in the other, attempts are made to prevent growth on the mask, so that over a whole slice the only deposition that will occur is in the unmasked regions. The present work is concerned with only the latter case, and specifically with silicon. Joyce and Baldrey1 suggested the use of thermally grown silicon dioxide as a mask material and showed that for the proper choice of operating conditions (total flow, SiCl4 concentration, total deposition time, and temperature) spurious growth could be minimized and that if the deposition times were not too large, and the criteria not too stringent, a usable process occurred. Later Schnable et al 4 observed that after extended deposition times, during which most of the silicon dioxide became covered with growth, there was always a band of oxide around the exposed silicon area that was quite free of spurious silicon crystallites. This latter observation is particularly intriguing since it extends the hope that with proper precautions masking can be much more versatile than it presently is. EXPERIMENTAL PROCEDURE Silicon substrates oriented to within 1.5 deg of a (111) plane were prepared by etch polishing lapped

Jan 1, 1967

By H. H. Dievendorff, F. W. Hertel

The method of drilling deep wells into the earth for the recovery of oil and gas is beset with many hazards. This is especially true in the Ventura Avenue field, which has the distinction of being the hardest field in California in which to complete a deep well. The hard, shifting and squeezing formations must be penetrated to great depths in the face of tremendous gas pressures. This field presents problems that keep the operators abreast with all of the latest developments in oil-field tools and machinery and in oil-well drilling practices. Equipment must be strong, and adapted to deep-well drilling and the handling of long heavy strings of casing. High-pressure sands require the utrnost care and attention of the operators and no chances can be taken, since a serious blowout may cause the loss of a well that has cost months of labor and expense. Equipment must meet these requirements or be discarded. Although the deepest wells in the world are not in this field, nor hav:. the longest strings of casing been set, nevertheless, the consistency with which deep wells are drilled and long strings of casing are set places the Ventura Avenue field foremost, in this respect, among the oil fields of the world. The V'entura Avenue field dors claim the deepest commercial oil-producing well in the world, in the Shell Co. of California's "Edison" No. 18. This well was drilled 7015 ft. and came in flowing 3280 bhl. of oil per day. This field also claims the deepest average depth of producing wells in that its Ill producing wells average 5676 ft. in depth. Of these 111 producing wells, 50 arc 6000 ft. or deeper, and 16 are 6500 ft. or deeper. Also, of the 111 producing wells 100 arc flowing, and 11 arc pumping wells. This paper is intended to set forth the methods used in the drilling of deep wells with rotary tools and the handling of long heavy strings of casing in the Ventura Avenue field.

Jan 1, 1928

By Doll. H. G.

THIS paper discusses a method and apparatus for determining the dip of formations traversed by a drill hole, by means of electrical measurements in the hole. The process consists in recording the Spontaneous Potentials present along three oriented generatrices in the hole, By comparison of the three curves thus obtained, after application of a correction factor to compensate for any deviations of the hole, the dip angle and the dip direction are determined. Excellent accuracy is obtained for dip angles over 10°. Because the method is simple and the apparatus rugged, the measurements are rapid and reliable; consequently, they can be made at all the levels that are of interest at any time after the well has been drilled. Mechanical cores are not needed to evaluate the dips. A convenient, time-saving procedure is to perform the dipmeter survey at the time the electrical log is taken, using for both operations the same cable and truck. Actual examples of results obtained in wells of the Gulf Coast area are given.

Jan 1, 1942

By A. L. Hornbaker, S. D. Schwochow

Industrial minerals are becoming increasingly important in Colorado's mining industry, not only in production value but also in the variety available and in their potential development for both conventional and new uses. Fluorspar, building stone, fire clay, and pegmatite minerals have been historically important but are not now extensively mined. Aggregates (sand, gravel, and crushed stone), cement materials, metallurgical limestone, and common clays currently are the highest valued commodities. Those offering the greatest future potential include diamonds, nahcolite and dawsonite associated with oil shale, alunite, potash, zeolites, and rare earths.

Jan 1, 1982

By AIME AIME

TECHNICAL achievement in mining will be rewarded at the forthcoming Annual Meeting of the Institute when the William Lawrence Saunders Gold Medal will be presented to Herman C. Bellinger. Mr, Bellinger was unanimously selected on the first ballot of the Medal Committee. Mr. Bellinger has had notable technical success as vice-president in charge of operations for the Chile Exploration Co., a position he has held since 1920.

Jan 1, 1941

By Arthur Gray

THE thermal analysis of a metal or alloy is ordinarily made with the aid of heating and cooling curves, in which transitions are indicated by the rapid changes in curvature that accompany .changes in the rate of heat absorption or evolution. Analysis by the method that depends on the change in thermal expansivity is not customary, partly, at least, because of the difficulties involved in making the necessary measurements. However, under certain circumstances, the dilatometric method of analysis may possess advantages over the thermometric method that will justify the additional trouble required. The addition of 1 per cent. of zinc to an alloy has been found to produce, upon the volume changes that take place during transition, effects that suggest the possibility of using the dilatometric method of thermal analysis as a rather sensitive means of obtaining chemical information. Although the illustrations presented in this paper are drawn from data obtained during an investigation of dental amalgams, similar phenomena can doubtless be observed with other alloys. Some of the results found during an investigation made in 19171 have been confirmed by data on the thermal expansivity of amalgams published by Souder and Peters of the Bureau of Standards in reporting tests of dental materials.2 Although the Bureau of. Standards made experiments for the purpose of discovering effects of including zinc as one of the constituents of a dental alloy-a matter much discussed in dental literature but without the presentation of reliable experimental evidence to support the views of ;either side-the reports of the test made by the Bureau give the impression that certain striking phenomena associated with the presence of zinc were not noticed. Among such phenomena are those connected with the conditions that determine whether or not a specimen of amalgam becomes covered with droplets from which crystals develop.

Jan 9, 1920

By Howard Willey

MINING operations of the Charcas unit at present are limited to the Tiro General mine at Charcas, in the State of San Luis Potosi, Mexico. The Tiro General mine was first operated during the Spanish occupation of Mexico for rich silver ores in an oxidized zone along the outcrop of the principal vein. In depth the ore is a complex sulfide with widely varying proportions of sphalerite, argentiferous galena and chalcopyrite; and until recent years, it was economically impossible to carry on mining otherwise than irregularly in sections of the veins richest in galena and chalcopyrite. The advent of selective flotation brought the orebody as a whole within the field of economic interest, and a flotation mill of 650 metric tons daily capacity was constructed in the year 1925. The mining of partly worked-out sections of the mine, as well as the very heavy ground in most of the stopes opened in virgin ore, presented an unusually difficult problem. This -paper describes the so-called "filled top slice" stoping method finally adopted as the standard system.

Jan 1, 1930

By R. L. Curfman

In May 1960, six months after conversion of one- half of the Uranium Reduction Co. mill from acid to alkaline leach, severe corrosion was encountered in the 112 stainless steel wash baskets in the resin- in-pulp portion of the uranium circuit. Fortunately the corrosion was limited to the stainless steel screen cloth and bolts. The frames were not affected. Each resin-in-pulp wash basket serves as a container and a vehicle for approximately 40 cu ft of ion-exchange resin. Four baskets are installed in each tank through which uranium-rich solution flows as the baskets move up and down mechanically in the tank. The ion-exchange resin has an affinity for the uranium in the solution which causes it to be deposited on the resin in solid form. By reverse action with different chemical solutions, the uranium may be stripped from the resin for further processing and purifying. This section is the first step in the actual recovery of the uranium.

Jan 9, 1962

By S. W. Zanolli

The history of labor relations in the coal industry of the United States is a study of its collective bargaining. This study of collective bargaining is largely the history of the United Mine Workers of America and its contractual relations with the various coal mining employers who have produced this country's coal over the years under a free enterprise system. There have been other unions in the picture from time to time and some coal miners have mined coal without representation by any union. Even today some 25% of the nation's coal is produced outside of the collective bargaining relationship with the UMWA. However, more than 100,000 coal mine wage employees - well over 75% of the total in the industry - are covered by labor agreements negotiated for them by the UMWA. Practically all of these work in bituminous mines.

Jan 12, 1972