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By Ernest L. Ohle

The newly opened Hayden Creek lead mine represents a variation from the usual Southeast Missouri type. Galena mineralization occurs in sandy dolomite cementing a conglomerate of granite boulders and in cracks in the boulders. The conglomerate occurs at the base of the Bonneterre formation on the slopes of two buried pre-Cambrian knobs. IN 1943 diamond drilling from the surface in an area 2 miles southwest of Leadwood, Mo., discovered a lead deposit of a markedly different character from the usual southeast Missouri type. Subsequent drilling of about 500 holes indicated several million tons of ore, and in 1950 a 701-ft vertical shaft was sunk into the orebody. This paper describes the geology of this interesting occurrence insofar as it is known from the drilling and the small underground exposure at the bottom of the shaft. Geology The location of the Southeast Missouri Lead Belt and of the Hayden Creek property are shown in Fig. 1. As shown here, there are two separate producing areas, one from which the larger tonnage has come, located near Bonne Terre, Flat River, Desloge, and Leadwood, and the other to the south around Fred-ericktown and including famous old Mine LaMotte. The best published description of Lead Belt geology is by Tarr.* In pre-Cambrian time in this area, an assemblage of granites and rhyolitic flow rocks was eroded to a mature topography. Sedimentation, beginning in the Upper Cambrian, filled in the valleys and gradually covered even the highest hills. The first formation deposited was the La-motte sandstone; it is successively overlain by the Bonneterre dolomite, the principal lead-prodbcing formation, then the Davis shale. the Derby-Doerun limestone, and a succession of Cambro-Ordovician cherty dolomites. Several of these formations may be found in direct contact with the pre-Cambrian as their deposition progressively overlapped the older rocks on the flanks of the igneous knobs and ridges. Immediately overlying the pre-Cambrian there is, not uncommonly, a thin basal conglomerate of granite or porphyry boulders, which is incorporated into the overlying sediments. Deposition of the lower part of the rock section was fairly continuous, and the Lamotte sometimes grades almost imperceptibly into the lower sandy Bonneterre. Since the sediments were deposited on an uneven floor, they tend to reflect the irregularities in that floor. Most of the steep dips found in the district, that is, dips in excess of 10°, are original dips and not caused by deformation. Such domelike structures in the sedimentary rocks around the igneous knobs have localized a considerable number of the orebodies in the district and particularly those in the Frederick-town area. Many of the larger orebodies, however, have no close relation to the pre-Cambrian topography. Most of the lead production has come from the lower 150 ft of the Bonneterre formation, where disseminated ore spreads laterally parallel to the bedding for great distances. Average stoping height is about 20 ft, but in a few places there are stopes over 175 ft high.

Jan 1, 1953

By Ernest L. Ohle

The newly opened Hayden Creek lead mine represents a variation from the usual Southeast Missouri type. Galena mineralization occurs in sandy dolomite cementing a conglomerate of granite boulders and in cracks in the boulders. The conglomerate occurs at the base of the Bonneterre formation on the slopes of two buried pre-Cambrian knobs. IN 1943 diamond drilling from the surface in an area 2 miles southwest of Leadwood, Mo., discovered a lead deposit of a markedly different character from the usual southeast Missouri type. Subsequent drilling of about 500 holes indicated several million tons of ore, and in 1950 a 701-ft vertical shaft was sunk into the orebody. This paper describes the geology of this interesting occurrence insofar as it is known from the drilling and the small underground exposure at the bottom of the shaft. Geology The location of the Southeast Missouri Lead Belt and of the Hayden Creek property are shown in Fig. 1. As shown here, there are two separate producing areas, one from which the larger tonnage has come, located near Bonne Terre, Flat River, Desloge, and Leadwood, and the other to the south around Fred-ericktown and including famous old Mine LaMotte. The best published description of Lead Belt geology is by Tarr.* In pre-Cambrian time in this area, an assemblage of granites and rhyolitic flow rocks was eroded to a mature topography. Sedimentation, beginning in the Upper Cambrian, filled in the valleys and gradually covered even the highest hills. The first formation deposited was the La-motte sandstone; it is successively overlain by the Bonneterre dolomite, the principal lead-prodbcing formation, then the Davis shale. the Derby-Doerun limestone, and a succession of Cambro-Ordovician cherty dolomites. Several of these formations may be found in direct contact with the pre-Cambrian as their deposition progressively overlapped the older rocks on the flanks of the igneous knobs and ridges. Immediately overlying the pre-Cambrian there is, not uncommonly, a thin basal conglomerate of granite or porphyry boulders, which is incorporated into the overlying sediments. Deposition of the lower part of the rock section was fairly continuous, and the Lamotte sometimes grades almost imperceptibly into the lower sandy Bonneterre. Since the sediments were deposited on an uneven floor, they tend to reflect the irregularities in that floor. Most of the steep dips found in the district, that is, dips in excess of 10°, are original dips and not caused by deformation. Such domelike structures in the sedimentary rocks around the igneous knobs have localized a considerable number of the orebodies in the district and particularly those in the Frederick-town area. Many of the larger orebodies, however, have no close relation to the pre-Cambrian topography. Most of the lead production has come from the lower 150 ft of the Bonneterre formation, where disseminated ore spreads laterally parallel to the bedding for great distances. Average stoping height is about 20 ft, but in a few places there are stopes over 175 ft high.

Jan 1, 1953

By W. L. Falke, A. A. Cochran

A basic problem in connection with manganese is to find economical ways to utilize domestic resources. As a part of its program to conserve domestic mineral resources and to reduce dependence of foreign sources, the Bureau of Mines had conducted extensive research to broaden manganese technology and to find economical, technically-feasible processes for recovering manganese from these low-grade resources. This paper analyzes some of the major difficulties which have been encountered in previously proposed processes for treating low-grade manganese ores and discusses a process which may circumvent many of these difficulties. Vast deposits of low-grade manganese ore exist in the U.S., yet domestic production is insignificant compared to the more than 2 million tons of ore imported yearly into this country.' A basic problem in connection with manganese is to find economical ways to utilize domestic resources.2 As a part of its program to conserve domestic mineral resources and to reduce dependence on foreign sources, the Bureau of Mines has conducted extensive research to broaden manganese technology and to find economical, technically feasible processes for recovering manganese from these low-grade resources. Although a great many processes have been proposed for treating domestic manganese resources, a failing of many of them is that too many steps are involved for economical operation.' Some of the major processes that have been proposed were reviewed by Norman and Kirby.3,4 Chlorination processes have become increasingly useful as a means of recovering valuable metals from raw materials, because the relative cost of chlorine (Cl2) and hydrogen chloride (HC1) has decreased through the years, and because the corrosion resistance of materials of construction has been improved. The objective of these processes is to form metal chlorides that are more volatile or water-soluble than are the corresponding oxides or sulfides; these compounds then can be separated from the gangue or other minerals by volatilization or leaching. Several chlorination processes for the recovery of manganese have been investigated by the Bureau of Mines5-8 and others; the major chlorination processes were reviewed in 1963, and their main features were compared.4 In all these processes, the simultaneous leaching or volatilization of iron chlorides with manganese chloride (MnCl2) is a problem, and the more iron that is present, generally the greater the problem. The leaching step is not highly selective, and the product of this step is, at best, suitable only for the production of ferromanganese or for further processing to remove iron. The product of the volatilization step is, in all cases, a mixture of iron and manganese chlorides that contains too much iron even for ferromanganese production, and must undergo additional processing steps for iron removal. THERMODYNAMIC CONSIDERATIONS The literature indicates that the desired chlorination reactions will proceed at practical rates at temperatures near 1200°K (927°C). Free energy changes at 1200°K for the critical steps of the reduction and chlorination reactions9-11 follow: Most of the research on chlorination processes for manganese recovery has been done with HC1 rather than with C12, for the following three main reasons: 1) Recycling of the chlorinating agent, which is economically vital, appeared to be easier for HC1

Jan 1, 1968

By E.G. Lewis, l.M. Barker

The literature of milling is replete with papers devoted to the subject of ball milling, all of which no doubt have contributed in one way or another to progress in that art. In this paper reference will be made to only a few of the many authors, but the value of the contributions of all who have written on that subject is hereby acknowledged. With a few exceptions the efforts of most students of the subject have been devoted to laboratory investigations of principles. Davis1 was one of the first to report on plant-scale investigations and to present to mill men certain criteria for the guidance of ball-milling practices. His conclusions with respect to the significance of sizing analyses of classifier sands in their relation to the factors of mill speed and ball sizing are particularly referred to. Those conclusions were: 1. If the balls are large or the speed of the mill is high, crowding will appear at the finer sizes in the classifier sands. 2. If the balls are small or the speed is low, crowding will appear at the coarser sizes in the classifier sands. 3. The indications are that best efficiency is obtained when the screen analysis of the sands show a minimum crowding at any size. The last conclusion was qualified by the statement that it had not been proved conclusively. It is surprising, however, that the litera- ture of later years reveals little evidence that millmen have made any serious attempt to apply those criteria. This may, perhaps, be explained by the fact that the average plant-scale ball-milling problem presents so many variables that an investigation of any one of them encounters the problem of control of the others—a problem that often is unsurmountable in a small plant. In a large plant, in which there is a duplication of grinding units in parallel operation, opportunity may be afforded for determining the value of such criteria. Nevertheless, a study of published data from grinding circuits of both large and small plants suggests that either Davis' criteria have been tried and found inapplicable or have never been given consideration. For the purpose of testing Davis' conclusions and with improvement of ball-milling efficiency as the final objective, a test program was initiated in the concentrator of the New Cornelia branch of the Phelps Dodge Corporation early in 1938. The practices of that plant have already been described.2 The fine-grinding units are arranged so that any one of eight units may be operated as a test unit and its results compared with those of the remaining units. All units receive similar feed from a common storage bin, in which the product of the fine-crushing plant is bedded by traveling tripper. The ball mills are all similar in size and operated at the same speeds, and are individually metered. The feeder conveyors of each unit are equipped with Merrick weightometers. The test program as initially outlined proposed investigation of the following:

Jan 1, 1943

By L. M. Barker, E. G. Lewis

The literature of milling is replete with papers devoted to the subject of ball milling, all of which no doubt have contributed in one way or another to progress in that art. In this paper reference will be made to only a few of the many authors, but the value of the contributions of all who have written on that subject is hereby acknowledged. With a few exceptions the efforts of most students of the subject have been devoted to laboratory investigations of principles. Davis1 was one of the first to report on plant-scale investigations and to present to mill men certain criteria for the guidance of ball-milling practices. His conclusions with respect to the significance of sizing analyses of classifier sands in their relation to the factors of mill speed and ball sizing are particularly referred to. Those conclusions were: 1. If the balls are large or the speed of the mill is high, crowding will appear at the finer sizes in the classifier sands. 2. If the balls are small or the speed is low, crowding will appear at the coarser sizes in the classifier sands. 3. The indications are that best efficiency is obtained when the screen analysis of the sands show a minimum crowding at any size. The last conclusion was qualified by the statement that it had not been proved conclusively. It is surprising, however, that the litera- ture of later years reveals little evidence that millmen have made any serious attempt to apply those criteria. This may, perhaps, be explained by the fact that the average plant-scale ball-milling problem presents so many variables that an investigation of any one of them encounters the problem of control of the others—a problem that often is unsurmountable in a small plant. In a large plant, in which there is a duplication of grinding units in parallel operation, opportunity may be afforded for determining the value of such criteria. Nevertheless, a study of published data from grinding circuits of both large and small plants suggests that either Davis' criteria have been tried and found inapplicable or have never been given consideration. For the purpose of testing Davis' conclusions and with improvement of ball-milling efficiency as the final objective, a test program was initiated in the concentrator of the New Cornelia branch of the Phelps Dodge Corporation early in 1938. The practices of that plant have already been described.2 The fine-grinding units are arranged so that any one of eight units may be operated as a test unit and its results compared with those of the remaining units. All units receive similar feed from a common storage bin, in which the product of the fine-crushing plant is bedded by traveling tripper. The ball mills are all similar in size and operated at the same speeds, and are individually metered. The feeder conveyors of each unit are equipped with Merrick weightometers. The test program as initially outlined proposed investigation of the following:

Jan 1, 1943

By Henry G. Granger

DURING upwards of three thonsand miles of canoc-travel in South America, including several mishaps, the writer has unfortunately lost his book of notes taken during the year 1894 in Dutch Guyana, or Surinam. But a year spent in a foreign country, visiting its principal mining properties, is necessarily productive of indelible memories and impressions, and some of these may be of interest to the Institute. The Guyanas include British, or Demerara, Dutch, or Surinam, French, or Cayenne, and the Disputed Territory, or that portion of Brazil on the northeast coast of South America. After passing the picturesque mountainous coasts of Colombia and Venezuela, one reaches a low, flat mud-bank which extends far out into the sea, so that from the steamer, over a couple of leagues of turbid, shallow water, one call just see the dismal outline of the pestilential "bush" that fronts the Caribbean sea, clear around to the mouth of the Amazon. Here, iii the order mentioned above, are the Guyanas. So much has been said about this out-of-the-way section during the late excitement over the Venezuela boundary question, that the historical part of the subject may be advantageously condensed. Gold-mining in the Guyanas is altogether placer-mining, and is of the same general nature throughout; hence by describing the methods in use in Surinam and the results there achieved, ail idea will be given of the work throughout the field. The product of this section is about three to four millions of dollars annually, mostly from Demerara, not because of superior richness of its placers, but as a result of its very much larger population, which exceeds twice the aggregate census returns of both Surinam and Cayenne. Mining ill all this section is of comparatively recent date, and is indirectly due to the decline of the sugar-industry. After the introduction of beet-sugar scores

Jan 1, 1897

By A. S. Learoyd

The Anthracite Division, Bureau of Distribution, of the United atates Fuel Administration, came into existence about Oct. 20, 1917. There had been no definite policy determined upon and the distribution had been carried out by the producers and distributors of this fuel as under normal conditions. The domestic sizes had been shipped from the beginning of the coal year on Apr. 1 in about their usual proportions to the various sections of the anthracite consuming territory of this country, which, in a general way, extended as far west as Nebraska and Montana, and in the south along the Atlantic seaboard to Florida. With the advent of cold weather, about the middle of November, acute shortages commenced to develop all over the northeastern section of the country, due to largely increased demand by the public in general, to enormously increased population in centers where industrial war activity was concentrated, and by the needs of the war industries themselves. Commencing with the early part of December, this demand was aggravated by extreme low temperatures and heavy snow; and the production decreased for the same reasons. From that date until the change in the weather, about the latter part of February, it was simply a question of getting coal into communities as emergencies occurred, to take care of individual cases. No definite plan of distribution could be followed. The coal mined between Apr. 1 and Nov. 1 had been distributed as mined and therefore only current production was available for distribution. The Anthracite Division, during this period, consisted of a Director, two assistants, together with an office force .of seven or eight clerks and stenographers. The trying experiences of the winter of 1917-18 had, however, shown a ready willingness on the part of the anthracite operators and distributors to cooperate in every way with the United States Fuel Administration. It was realized that if a definite and comprehensive plan of distribution could be formulated to become effective Apr. 1, 1918, determined on the actual needs of each state and community, the producers

Jan 1, 1920

By Howard C. Dunkle

Various factors can affect the quality of B1112 and B1113 steel as produced in a bessemer plant; among them: vessel-charging practice, blowing practice, ingot-pouring practice, ingot delivery-time practice, pit-heating practices, and ingot-rolling practice. Evaluation of the influence of ingot delivery time on quality has been chosen as the subject for this paper because this time is completely within the control of the operator, and on this particular factor there is a tremendous amount of information in the dusty archives of the average steel plant. In order to know how much improvement can be made and when attention should be directed to other factors that influence quality, in the continual struggle for improvement, the effect of ingot delivery time must be accurately evaluated. Once this is done, the importance of other variables can be accurately obtained, thus eliminating the necessity of resorting to opinions that are of doubtful value at best. In the study described herein, extensive use was made of the statistical card system as a method of determining the effect of ingot delivery time as a quality factor in bessemer screw-stock grades by simple direct correlation. The value of this statistical method as a means of accurately determining the influence of various factors has been amply demonstrated by Work1 for the bessemer process and by Hand and Gould2 and Fetters and Chipman3 for the open-hearth process. The quality records of 300,000 tons of bessemer screw-stock billets were used in this study of the effect of ingot delivery time on the rejections for breaks, pipe, check and seams. The reduction in the number of rejections for poor quality reduces the costs and increases the productivity per man-hour. The operator today, more than ever before, must know how to keep costs down, how to do it most quickly and in the best way, and how to obtain the highest quality in line with the ever increasing demands of the customer. It is necessary for him to know the individual relations and interrelations between various factors affecting the quality of the manufactured product if he is to produce material that will meet competitively the cost, performance, and quality demands of the trade. SIGNIFICANCE OF STEEL MANGANESE, MIXER SILICON AND STEEL SULPHUR AS QUALITY FACTORS In order to obtain the highest grade of material it is necessary to control many factors-not just one or two, as operators

Jan 1, 1945

By W. O. Hotchkiss

DURING the summer of 1927, the Department of Terrestrial Magnetism of the Carnegie Institution of Washington joined with the Michigan College of Mining and Technology in conducting a series of earth-resistivity measurements in the Michigan copper country. The geological structure in this section is quite varied and fairly well known. The purpose of the investigation was to discover the correlation between the variations in electrical resistivity of large masses of soil and rock in place and the geological structure below the surface. The work done may be roughly divided into two parts: (1) Measurement and study of the variations in resistivity with depth, or with volume, to establish such general relations as exist between the two: and (2) the determination of the specific resistivity of various formations in order to make available more fundamental data which may aid in the interpretation of the results of the former type of measurement. A report by Mr. Rooney, which gives in detail the measurements made and the results obtained, forms the basis for this article. MEASUREMENT AND STUDY OF VARIATIONS IN RESISTIVITY The possibility of applying data from measurements of the physical properties of earth material to the 'study of the geological structure has long been recognized, and a number of methods for determining the position and character of concealed rock strata by means of seismic, gravitation, magnetic and electrical measurements made on the surface are being used with varying degrees of success. One physical property which varies widely for different materials, and hence affords an opportunity for distinguishing between them, is their electrical resistance. Locations were selected where the geological structures were well known and where the depths to the water level and bed rock had been determined by drilling. The problem was to determine the value of measurements of resistivity and its variations as indications of the geological structure below the surface.

Jan 1, 1928

By F. J. Mehringer, C. W. MacGregor

VARIOUS investigations have been carried out to determine the effects of cold-rolling on the common physical properties as represented by the yield strength, tensile strength, percentage of elongation and ordinary reduction of area. Very little information is available in the literature with reference to the effects of cold-rolling on the true stress-strain properties. Since the ordinary physical properties base both the stresses and the strains on the original dimensions of the test piece, which are greatly changed during the test, they are essentially empirical values and do not represent physically either true stresses or true strains. Consequently, they do not give an accurate picture of the effects of different conditions, both mechanical and metallurgical, on the strength and ductility of the material. It is not, however, the purpose of this paper to review the various advantages accruing from the use of true stress and true strain values, since these have been shown elsewhere,1-12 but to utilize them in representing the various effects considered. The true stress S and true strain (e = q') values mentioned above for the tension test are defined by1 [ ] where P, A, Ao are the axial load, the instantaneous area and the original area of cross section, respectively. From simultaneous readings of the axial load and the dimension or dimensions determining the instantaneous area of cross section, the true stress-strain curve is constructed by using the relations given in Eq. I. It is then the object of this paper to discuss the general effects of cold-rolling on the true stress and strain values for a low-carbon steel together with the effects of age-hardening and directionality on these properties. PRELIMINARY INVESTIGATIONS The material considered throughout the paper is a low-carbon steel of the following chemical analysis: C, 019 per cent; S, 0. 118; P, 0.092; Mn, 0.85; Si, 0.01. The stock was received in bars, 7 by 3/4 in., and was first annealed for one hour at 1650°F. followed by a furnace cool. Photomicrographs of this material showed considerable directionality even in the annealed condition. In view of the possible effects of the nonhomogeneity and directionality in this material, it was considered important to investigate their influence on the true stress-strain diagrams. In addition, the effect of strain-aging in this steel was also made the subject of a preliminary study. Elect of Aging on True Stress-strain Properties Since a certain time element would elapse between the cold-rolling operation and the final tension tests, it was determined to investigate the aging character-

Jan 1, 1945

Jan 1, 1932

By Rossiter W. Raymond

The formal outline of Mr. Hague's life and work is embraced in the following statement, chiefly based upon data furnished by him, at my request, shortly before his death. At that time the probability that I would survive to record his death was apparently small; but I urged upon him the duty of providing, whether for me or for my successor as Secretary of the Institute, trustworthy material for the notice which somebody would some day have to write—and which might otherwise be incomplete or incorrect. Mr. Hague, with characteristic promptness and freedom from affectation, did what I asked of him; and I am therefore able to present an authoritative sketch—concerning the details of which I shall add my own comments, and some particulars obtained from friends. James Duncan Hague was born Feb. 24, 1836, at Boston, Maes., where his father, Rev. William Hague, D.D.,an eminent clergyman, then resided. After a preliminary education in private schools, he studied in 1854 at the Lawrence Scientific School of Harvard University; in 1855 and 1856 at the University of Göttingen, Hanover; and from 1856 to 1858 at the Royal Mining Academy of Freiberg, Saxony. In 1859-1861 he was attached as chemist to a South Sea exploring expedition, sent by W. H. Webb, of New York, to examine Jarvis, Baker, and other islands for phosphate-deposits. After the outbreak of the Civil War, he entered the U. 5. Navy, serving for a year as Judge Advocate to the fleet stationed at Port Royal, S. C. In 1863 he became Superintendent of the Albany and Boston copper-mine, in the Lake Superior region, where he was also connected with the earliest development of the Calumet and Hecla property. In 1867 he became the First Assistant Geologist in Clarence King's famous Exploration of

Jan 1, 1909

By D. H. Gieskieng

Published tables of jaw crusher capacities are compiled for the most part from field performance data, interspersed with interpolations, extrapolations, various safety factors, and other modifications. Such a table attempts to balance and equalize field data from widely Werent materials, with differences of crushability, efficiency of feeding, sizing of the feed, and so on. The tests described in this paper were undertaken with the objectives of checking previously reported capacities; of studying the effects of various factors upon the capacity, including jaw plate curvature; and, if possible, of deriving a general capacity equation. Such an equation has been derived from the data obtained in these tests. It is given together with factors for its use. While more accuracy than is usually required may be obtained by careful application of the equation, it is of simple form and provides a convenient reference plane upon which the potential capacity of various crushers may be compared, and with which operating adjustments may be made on existing installations. The principal deviation in these tests from the usual approach consists of a laboratory technique which has been developed for the production of selected capacity data. Recording instruments are connected to crushers in such a manner that a continuous record is produced which discloses the inherent maximum capacity of the crusher and shows capacity decreases caused by hangups. The capacity effects of various crushing conditions are made more evident by this arrangement. The recording instruments were first applied to a standard sized 10 by 7 in. Blake-type jaw crusher in the laboratory. Suficient tests were run on this with various combinations of setting, throw, speed, feed sizing, shapes of jaw plates, and other operating features, to establish the individual effect of each on the capacity. The instruments later were applied to much larger crushers in the field, through the excellent cooperation of the managements in the Mesabi Iron Range, and data were obtained which closely corroborated the established trends. The capacity equation resulting from the test work is made up of a series of factors, each representing the contributing effects of setting, speed, width of chamber, nip angle, feed density, type of jaw plates, stroke, and the overall operating technique. Fortunately, most of these factors were revealed to be in direct proportion to the capacity for straight plate chambers. This equation is also applicable to chambers using curved plates, with slight modifications resulting from the capacity limitation of the upper portion of the crushing chamber. The equation has been derived from tests covering a very wide range of feed density and hardness. It has been found valid, providing that the feed material is either nonpacking in character, as is usual, or allowance in designing the crushing chamber shape has been made to accommodate this characteristic. Preliminary investigation has shown that the equation is also applicable to single-toggle jaw crushers. Conditions of this are that the top of the flywheel rotate towards the top of the crusher opening, and that the horizontal motion of the swing jaw relative to the stationary jaw at the discharge opening be considered as the stroke. The relatively large upper chamber jaw motion would probably result in realiza-

Jan 1, 1950

By L. B. Slichter

It has been estimated that rock exposures in most mining districts aggregate less than 1 per cent. of the total surface area.1 Conclusions concerning the hidden 99 per cent. necessarily have been based on knowledge of only a small fraction of the surface, and from this limited information the geologist has been obliged to deduce the approximate and general nature of the underlying formations. In the search for ore it is necessary to supplement this general picture with greater detail. Fairly accurate knowledge of relatively small zones is required. This knowledge is carefully sought in many different ways—detailed interpretations of geological history, the tracing of float, the use of test pits, of trenching, of drilling, and of other methods. Practical ingenuity, scientific brilliance, great perseverance and patience, and the expenditure of large sums of money have all been a part of this search. The problem of exploring beneath cover with economy, and of obtaining essential information which this cover hides, is obviously a difficult one. It is also a very important one, for geologist's inform us that already the story of the 1 per cent. exposed outcrops has been largely read.V here remains the nearly virgin field comprised in the hidden 99 per cent.: and the importance of this zone is bound to increase continually. In recent years, the problems connected with the exploration of this "99 per cent. zone" have attracted a constantly enlarging group of investigators and at present greater efforts than ever before are being made to resolve them. This work, in it's various special aspects, has enlisted, beside geologists, the cooperative efforts of chemists, physicists, and mathematicians. The progress made in this development should be kept before those directing explorations in order that due advantage may be taken of a changing situation. My subject concerns certain aspects of one of the older physical methods of exploration, the magnetic method. This method is familiar in principle to most of us, arid because of its age., is especially suitable for

Jan 1, 1929

By D. Duffey, P. F. Wiggins, F. E. Senftle

An examination of the neutron capture gamma ray method using a 252CF neutron source indicates that this technique may be feasible for process stream analysis of ores. Simulated laboratory experiments were made on iron in taconite and magnetite, and copper and nickel in their respective ores. Satisfactory analyses were obtained for 500-1000-g samples in a combined irradiation and counting time of 100 min. For large industrial size samples this time could be shortened. Based on these experiments, a set of guidelines are given for the use of the neutron capture gamma method in an industrial mill.

Jan 1, 1974

By B. B. Zavoico, J. G. H. Crump, P. P. Gregory

West Texas was the scene of greatly increased oil activity during 1937, producing 75,743,000 bb1.l in that year as compared with 61,901,-000 bb1.2 in 1936, an increase of 22.36 per cent. The annual total of wells completed increased from 15863 in 1936 to 28062 in 1937, an increase of 76.92 per cent. Of the total completions in 1937, 2464 were oil wells,2 11 gas wells2 and 331 dry holes.2 The marked increase in the number of oil wells completed in West Texas during 1937 had a substantial effect upon the daily average production per well, which decreased 20.84 per cent from December 1936, when a total of 5310 wells3 produced 5,236,467 bbl.3 for an average of 31.81 bbl. per well per day to December 1937, when 7571 wells2 with a total production of 5,910,257 bb1.2 averaged 25.18 bbl. per well per day. Drilling blocks and checkerboard acreage were being acquired following geophysical work in the northern end of the Permian Basin area, composed of Bailey, Cochran, Hockley, Yoakum and Terry Counties, presaging extension of active development northward. During 1937, at one time 30 geophysical crews were working in West Texas, and an average of 15 to 20 crews was active in this area throughout the year. Discoveries Wasson-Denver Field.—Wasson-Denver field in Gaines and Yoakum Counties was the outstanding field discovery of the year. Production is from porous limestone found at about 5000 ft., and an average well is good for from 300 to 500 bbl. of crude oil per day through 3/4-in. choke. The discovery well was drilled by A. G. Carter and others on the Wasson Ranch, Gaines County, and the field has since been extended into Yoakum County. At the year's end 21 wells had been completed, producing

Jan 1, 1938

By Pierre Hines

THESE notes are based on observations made while on a recent trip through the West, for the purpose of studying the practical operation of the ball-mill. The writer takes this opportunity to express his thanks for courtesies extended at the many plants visited as well as for the valuable data received. While there are several types of ball-mill on the market, particular attention will here be given to the diaphragm type, as the open-trunnion type, especially the conical mill, has been thoroughly discussed in the Transactions. There is a prevailing impression that the ball-mill is a recent development; however, ball-mills were used extensively in Montana and other western states for crushing ores for concentration as far back as 1898. Its present prominence is due in part to its recent successful application by one of the large copper companies. Without any reference to dry grinding, the first successful ball-mill for wet crushing, which is still in operation, was built 10 years ago.1 This mill, designed by Erminio Ferraris for crushing Sardinian ores for concentration, is of more than passing interest. It embodies the peripheral discharge with grates, large forged-steel balls, and the principal features of the modern ball-mill. The results approach present-clay practice, the chief differences being that the mechanical construction has been improved in the modern types.

Jan 2, 1918

By Tracy Jarrett

In 14-karat gold alloys, as in 10-karat gold alloys,3 the addition of such metals as zinc, nickel, copper and silver produces a wide range of physical and chemical proper-ties such as color, hardness, corrosion resist-ance and melting points. These important factors made gold alloys desirable in the optical work and for jewelry. In 14-karat gold alloys, as well as in 10-karat or 12-karat, it is possible to have two golds of the same color, one of which will corrode more than the other, although it may be harder. Some of these alloys have been investigated by F. E. Carter,1 E. M. Wise,5 and L. Sterner Rainer.4 In this group of alloys the gold content of 58.3 per cent (14-karat) was held constant, while the copper varied from 36 to 24 per cent. The balance of the alloy consisted of one, two, or three of the metals silver, zinc, and nickel. All the alloys were melted in an induction furnace and cast into an ingot that meas-ured 3 by 1/4 by 3/4 in. The method of determining the melting points, color deter-minations and acid test have been discussed in previous papers by the author.2,3 It is necessary to use small test bars (Fig. r). The tensile bars were annealed at 1300°F. for 20 min. and then air-cooled. There being a very marked drop when the yield point was reached, "the drop of the beam" method was used in determining the yield point.

Jan 1, 1940

By C. L. Clark, J. Russ

FOR many years attempts have been made to develop a laboratory test that would serve to indicate the proper temperatures to be used in the various hot-working applications to which metals may be subjected as they are being processed from the cast ingot to the desired finished products. That these attempts have not been very successful is indicated by the fact that most of the temperatures in use today in these operations have been developed over a period of years by trial and error. In other words, the selection of the proper temperatures for the hot-working of metals is generally an art rather than a science. Our knowledge with respect to the behavior of metals at elevated temperatures has been greatly extended during the past several years. While most of the work in this field has been done at proposed operating temperatures of equipment, rather than at processing or fabricating temperatures, one outstanding fact has been developed, which is applicable to the entire high-temperature range; that is, that the rate of deformation to which the metal is subjected is of the same order of importance as the temperature. The failure to properly recognize this fact has greatly retarded the development of a suitable laboratory test for determining hot-working temperatures. INFLUENCE OF RATE OF DEFORMATION ON HIGH-TEMPERATURE PROPERTIES It is not the intent of this paper to survey all the work that has been done on the effect of deformation rate on the properties of metals. The importance of this factor, however, was shown by Zay Jeffries1 as early as 1919, when he called attention to the existence of the so-called equicohesive temperature and to the effect of certain factors on the location of this temperature. Fig. I is a diagrammatic sketch showing the effect of temperature on the relative strength of the crystals and grain boundaries and the type of fracture that will result, depending on the location of the test, or working temperature with respect to the equicohesive temperature. Since the type fracture varies, it also follows that at temperatures below the equicohesive temperature the major deformation occurs in the grains; while at temperatures above, the deformation results either from the movement of the grains with respect to each other or recrystallization of the strained material occurs almost instantaneously, producing new crystals at the fracture. As previously indicated, it is an established fact that the position of this equicohesive temperature for any given metal is dependent on the deformation rate. For example, in 0.15 per cent plain carbon steel the location of this temperature under

Jan 1, 1945

By John Johnston

The actual amount of any metal volatilized from a mixture of metals depends on the magnitude of its partial vapor pressure under the specified conditions of temperature, and on the circumstances attending the heating—in particular, on the duration of heating, the volume of gas coming into actual contact with the surface of the metal, the extent of this surface, and the rate of diffusion of the volatile metal from the body of the melt toward the surface.' If two (or more) metals are volatilizing from the same mixture of metals, the several conditions are identical except for the difference in partial pressure and in rate of diffusion of the volatilizing metals; the second of these two factors is without doubt only of secondary importance as it is probable that the rates of diffusion of the volatilizing metals would be very similar. Hence, in order to gain an estimate of the relative amounts of two metals that may be volatilized from a given mixture, it is necessary to know the vapor pressure, or, more precisely, to ascertain for each metal its partial vapor pressure in equilibrium with the liquid (or solid) alloy under the particular circumstances. The partial pressure of each constituent depends on the effective concentration of that constituent in the alloy2 as well as on the vapor pressure of the constituent when pure, and it can be calculated when both of the above factors are known. The first step, therefore, is to ascertain the vapor pressure of the several pure metals. Vapor Pressure of Pure Metals The experimental data on the vapor pressure of the several pure metals with which we are here concerned are not so accurate as could be wished, nor have the determinations been made in general at temperatures such that the results can be used directly. In a previous

Jan 1, 1919