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By H. Landsberg

SUBSIDENCE caused by mining operations has been a matter of interest for the mining engineer for just 111 years, since the Belgian Committee for study of subsidence in the city of Liege submitted its first report in 1825. This interest is fairly expressed in the enormous amount of literature that has since appeared on this subject. A bibliography, probably far from being complete, which preceded this study as a pre-liminary survey, comprises more than 800 titles. In spite of this fact the problem remains today as acute as it has ever been. The questions of as good a recovery as possible of the national resources, the safety of the operations, and the protection of private and public property are the important angles from which to look at the problem.

Jan 1, 1936

In 1934 the Southern Experiment Station of the U.S. Bureau of Mines in. cooperation with the University of Alabama began an investiga-tion of the availability of kyanite ores as a source of raw material for the manufacture of refractories. Under this program, gravity concentration and flotation tests have been made on two varieties of Georgia kyanite ore, mica schist and massive. Most of the attention has been directed to the mica schist ores, as they are more widely distributed and seem to offer greater economic possibilities than the massive ores. It is evident that the preparation of kyanite for use as a refractory material involves other considerations than the mere elimination of impurities. A concentration process that eliminates impurities satisfactorily may have to be followed by some additional treatment, since the final product must be of a coarse-ness and size ratio that will make it suitable for refractories manufacture. So far in the investigation at the Southern Experiment Station of the U.S. Bureau of Mines only the concentration problem has been considered, and this paper is intended as an interim report.

Jan 1, 1936

By Mark Malamphy

THE occurrence of outcrops of bituminous schists and sandstones impregnated with heavy asphaltic petroleum first directed attention to the Sao Pedro area as a possible source of commercial production of petroleum. Since 1920, more than 20 wells have been drilled in this area. The discovery of oil shows and small quantities of natural gas in some of the early wells led to the continuation of drilling in the hope that more important findings would result. During the early part of 1934, detailed magnetometer observations were made in this area, and a con-siderable number of torsion balance stations were occupied. The results of these geophysical observations help considerably to clarify the structure of the area and the very considerable amount of geologic information available makes possible a much more exact interpretation of geo-physical anomalies. In presenting the results of these observations, and interpretation of the geophysical data, certain actual case problems are included; i.e., geophysical anomalies due to anomalous masses of which the forms and positions are more or less known. Although anomalies due to igneous intrusions are probably more important to geophysicists in Brazil than in other countries, these data have a certain interest for all geophysicists, particularly because they were obtained in the south magnetic hemisphere, where the lines of magnetic force are directed upward, and in a region of moderately low inclination. This is considered as a geological-geophysical problem, and only passing mention will be given to the petroleum possibilities of the area.

Jan 1, 1936

United Engineering Trustees, Inc. H. G. MOULTON, 40 A. L. QUENEAU, '38 ALBERT ROBERTS, '39 The Engineering Foundation GEORGE D. BARRON, '40 A. L. QUENEAU, '38 Engineering Societies Library Board H. K. MASTERS, '38' A. B. PARSONS, Ex-officio F. F. SHARPLESS, '37

Jan 1, 1936

By Carl Floe

THE possibility of separating the various constituents of mixed ores or metalliferous products by differentially producing their soluble sulfates has not received the consideration that it deserves. The production of the soluble sulfate may be accomplished by baking the ore with sulfuric acid or by treating it with gases containing oxides of sulfur. This paper is primarily concerned with the first method. The procedure used was to mix the material with a solution containing a definite weight of sulfuric acid, baking the mixture at various tempera-tures and then leaching out the soluble sulfate with water. The amount of acid used was calculated to produce certain desired soluble sulfates. The temperature of baking depended on the decomposition points of the sulfates involved. The object was to prevent the formation of or to decompose certain sulfates while leaving a maximum quantity of another sulfate in a water-soluble form. This procedure has two possible advantages over the ordinary method of leaching with an aqueous solution of sulfuric acid. First, a more selective leach may be obtained, and second, the higher temperatures and stronger acid concentrations involved will permit a better recovery of materials that are difficultly soluble in relatively dilute aqueous sulfuric acid solutions. The method of sulfuric acid baking followed by water leaching is not new, as it has been applied in the treatment of various metalliferous materials such as the recovery of cadmium from flue dust1, the re-treat-ment of zinc leach residues2 and the working up of electrolytic slimes3.

Jan 1, 1936

By J. J. Pelley

NOT being a scientist, an engineer or a metallurgist, I consider it a very great honor indeed to be asked to address the American Institute of Mining and Metallurgical Engineers. Your program indicates that any lack of intricate and technical knowledge on my part in the field of metals will be well taken care of by others. Therefore, I believe any remarks that I have to make might well be devoted to the practical side of metals in railroad service and to the general railroad situation as I view it today. The experiments now being conducted on the railroads with so-called streamlined, light-weight trains and cars would not have been possible had it not been for scientific and engineering research in the past that made these lighter weight metals available. The railroads now have approximately forty units of these new trains in operation. Experi-ence with them will no doubt be a guidepost for future construction in that direction. While the best known experiments are in the passenger service, they are being extended into the freight service. Within the past three years there was constructed for the Association of American Railroads a new standard box car of ordinary carbon steel, in which, by reason of superior design, weight was reduced by 3500 to 4500 lb. under that of existing cars of like capacity. The Association is now testing a box car that weighs approximately six or seven tons less than practically all of the box cars of like capacity in service today. If these tests are successful a very large field for the use of lighter weight metals will immediately be opened, provided the costs of such metals are not too high. The fact that various experiments are being carried on with other classes of equipment constructed with so-called light-weight and non-corrosive metals no doubt will have a considerable effect upon the rebuild-ing of old equipment. The question then will be: How much can we afford to spend on the rebuilding of an old car weighing six to seven tons more than a new car constructed with the latest available materials?

Jan 1, 1936

By V. F. Parry, S. P. Burke

The presence of gas in coal mines necessitates the use of costly ventilation arrangements and the use of expensive mining methods. On the other hand, the gas itself in many instances is of considerable intrinsic value, and its separate recovery might conceivably be a profitable undertaking. This paper is concerned with a study of the movement of gas in coal strata with the object of determining the laws governing gas movement and thus making at least a preliminary step toward the solution of the more practical problem of its control or recovery. Naturally, so important a subject has received much attention from scientists and engineers. In most cases, however, the studies have been concerned with the origin1$, the amount" the composition3 and the method of retention4 of the gas in coal; or, from the more practical side, have been concerned with the phenonlena and conditions associated with outbursts5 or explosions and their control. Numerous studies also have been made of the permeability of coal to gas" of gas pressures measured in coal seams, etc. The authors are unaware, however, of any attempt to present a consistent or complete picture of the laws governing the movement of gas through the coal. Study in West Virginia A recent study conducted at this University7 gives the first presentation of the distribution of pressures in a small section of a coal seam. Holes were drilled into the coal rib to various depths and at various distances from the coal face. The location selected for study was as remote as possible from disturbing influences of mining operations, faults, "wants," etc. The pipes extending into the coal that were used to determine pressures were grouted into the borehole for the entire depth of the hole, and great precaution was taken to insure accurate pressure readings. A map of the geology of the region, a map of the probable boundary and extent of the coal seam, a current map of the mine and a

Jan 1, 1936

By J. Charles Miller

THE expansion of facilities for rapid transportation of perishables by train, truck and airplane has necessitated consideration of refrigerants of a minimum weight and volume per pound of cooling and has stimulated the use of solid carbon dioxide commercially. The gas probably has not had wide application in the past in air-cooling equipment for mines, theaters or buildings, owing to its thermodynamic properties, as will be deduced from examination of Table 2. However, consumption of the liquid in carbonating beverages remains a dominant factor. In addition to these uses, carbon dioxide is employed to a limited degree as an explo-sive in the liquid form, as a freezing agent in plumbing, in laboratories for low-temperature work, and in the manufacture of golf balls.

Jan 1, 1936

By D. Harrington

The occurrence of dusts in underground workings creates many difficult and, in some instances, contradictory and conflicting problems for workers, operators, and all others interested in health and safety in mining and tunneling. Moreover, there are many misconceptions both as to the actual effect of most dusts which may be encountered in underground work and as to remedial or alleviating measures. Although the harmfulness of mine dusts to health of miners has been mentioned by man; writers in ancient times, much of our really authentic knowledge of the effect of underground dusts upon health or safety in both coal and metal mines has been pained during the past 30 or 35 years. There has been, however, a considerable amount of generalizing from some local condition or occurrence or theory rather than arriving at conclusions after extended studies and observations made not only in mines and tunnels but also in town, camps, and plants, and comprising date on as many different mining and tunneling localities, conditions, etc., as could be secured with reasonable expenditure of time or money. This paper dives sortie observations based on the writer's 30 odd years of experience in and around both coal and metal mines, including approximately 20 years? close study of dust disease with detailed surveys and reports on dust occurrence and effects in considerably more than 100 mines in probably 20 States of the Union. The observatio are those of an engineer and in many respects conflict the with "going" ideas of doctors, pathologists, and others who have written on dust disease. Were the word dust is used in this p: per in connection with respiratory disease, it refers to solid particles which float or can float in the air breathed by workers. Although these particles are usually dry, they may be wet; in general, their dimensions are so small as to be invisible to the nailed eye. Dusts in coal mines which may be involved in the initiation or extension of explosions, are generally thought to be those which are smaller than 20-mesh in size but chiefly finer than 20-mesh; coal-mine dusts which are harmful to health of workers have essentially the same general physical characteristics as other dusts, but usually consist of smaller particles.

Jan 1, 1936

By G. A. Baird

With the exception of eight wildcat completions, which were unsuccessful and abandoned, all of the 1935 new drilling was performed in the proven fields. As of Dec. 31, 1935, 22 drilling rigs were in operation, of which 9 were at wildcat locations and the remainder were being used in new drilling in proven fields; in addition, 25 workover rigs (exclusive of cleanout rigs) were operating, all in the major fields. Production of Crude Oil.—Notwithstanding the considerable decrease in new completions during 1935 as compared with 1934, crude production mounted to a new high of 148,893,225 bbl., clean oil at 60' F., representing an increase of 12,532,579 bbl. over the previous record year, 1934, total of 136,360,646 bbl. This increase was due: (1) to the flush production

Jan 1, 1936

By W. W. Adams

Because of insufficient funds for printing, the Bureau of Mines was unable to publish its annual bulletin covering accidents at metal mines in the United States for the year 1933. A brief mimeographed summary of the principal statistical data for that year was released to the public late in 1934. Since then reports for 1934 have been received from the mining companies, and in order to avoid further delay in releasing this information to the mining industry and others interested in the prevention of accidents in mining, statistics for both years are presented in this publication with a minimum of interpretation and comment. The fatal-accident rate for the metal and nonmetallic mines (excluding coal mines) of the United States was more favorable in 1933 than in any previous year since 1911, the first year for which the Bureau of Mines obtained reports from the operators. Further progress was made in 1934, when the fatality rate was even lower than that of 1933. On the other hand, the nonfatal-accident rate, which had reached its lowest level in 1932, increased in 1933 and increased further in 1934, although not to such an extent as to prevent the rate for either of those 2 years from being better than that for any year previous to r1931.

Jan 1, 1936

Jan 1, 1936

By R. S. Dean

The function of the Metallurgical Division is to conduct investigations relating to the treatment of mineral products from the state in which they are mined to the refined metal or other unfabricated product. These investigations include scientific and practical studies of ore dressing, covering the crushing and grinding of ores, separation by gravity, flotation. and magnetic methods; the hydrometallurgical treatment of ores, including cyanidation and amalgamation of the precious metals; the smelting and refining of copper, lead, and zinc, as well as the rare metals; and steel-melting practices from the raw ore to the finished steel. The object of this work is to conserve natural resources and eliminate waste by furnishing information on current methods of metallurgical practice. making fundamental studies of metallurgical processes, and developing new processes to the point of demonstrating their practicability. The Division is made up of sections devoted to the several phases of this work, each section being headed by an investigator capable of supervising his particular work. The work is carried on at the experiment stations and field offices or in the field, whichever seems best suited for the work in hand. The following, projects should be mentioned as particularly outstanding among those consummated successfully during the year: 1. Application of the type of chemicals known in the textile industry as wetting-out agents to flotation and agglomeration of ores, particulary soluble salts such as sodium and potassium chloride which must be treated in saturated brine. 2. Demonstration or a linear relation between surface and coercive force in magnetic minerals and Its application to magnetic separation and to the determination of grinding efficiencies and other metallurgical data which require surface determination at very fine sizes. 3. Pilot-plant demonstration of the practicability of the reduction of iron ore by natural gas and conversion of this direct iron into steel by direct melting and by forging and rolling before melting. The structure and properties of the iron so produced were studied in detail. This report covers the fiscal year July 1. 1934, to June 30, 1935.

Jan 1, 1936

By E. W. Schilling

THE-separation of hematite by hysteretic repulsion was first brought to the attention of the public in 1922, by W. M. Mordey1. Three-years later another paper2 was published and after another four years a third paper3 appeared in the South African publications. Certain data were lacking in these papers. In order to continue the work intelligently a knowledge of the shapes of the hysteresis curves for certain minerals was very necessary. This information was not available until the present year4. It was known that reduction of certain ores rendered them amenable to this process of separation but definite data in. the form of curves showing exactly the effect of such treatment were lacking. Prob-ably our best source of information on the separation of minerals by the use of alternating-current magnetic fields today is the reports from the U. S. Bureau of Mines 5-7. It is not the purpose of this paper to tell the reader in detail how to make a commercial separator. Experimental models have recently been made7 and the results obtained have been so good that it is the opinion of the authors that the public will soon take an active interest in the subject and its development. The writers have constructed a separator that is considerably different in construction and operation from the two types described by Mr. Davis. This will be described; but the real purpose of this paper is to outline certain experiments and give curves showing data that have a fundamental bearing upon the practical construction of a separator of this type.

Jan 1, 1936

By R. P. E. Hermsdorf

THE electrolytic refining of metals for the removal of undesirable impurities has become a recognized necessity in the nonferrous field. Copper, lead, zinc, nickel, silver and gold have been produced in this manner for years. The United States Metals Refining Co., realizing that considerable quantities of lead and tin could be made available to the trade if a satisfactory method of purification of these metals could be established, decided to investigate the possibilities of electrolytic solder. In cooperation with Dr. Edward F. Kern, of the School of Mines at Columbia University, the company developed a process of electrolytic refining of lead-tin alloys using a tin-lead fluosilicate electrolyte. A pilot plant was installed in November, 1927, and the commercial unit was put in October, 1929. Since that time thousands of tons of electrolytic solder have been produced in this plant and consumed by all branches of industry that use solder.

Jan 1, 1936

By Alexander Deussen

The figures listed in a table for Gulf Coast fields given by L. P. Teas1 in 1934 are so greatly at variance with results that I have obtained from a serious study of this subject over a number of years, that I am disposed to challenge the correctness of Mr. Teas' figures as an accurate representation of acre-foot yields of Gulf Coast fields, and as regards at least two of the fields listed by Mr. Teas I desire to "put into the record" some figures that, according to my study, are more nearly in accord with what I conceive to be the actual facts. Upon investigation I find that Mr. Teas' figures, inadvertently no doubt, arc not what they purport to be. Apparently the figures were arrived at by considering as thickness of the producing formation the net thickness of producing rock corresponding "to the total of the net portions of the producing zones which actually yield oil into the drill hole"—and in following this method I am under the impression that Mr. Teas was acting under instructions of the Institute in the preparation of this paper, in order to get comparable figures from the several fields of the United States. Apparently the author interpreted these instructions to mean that in the absence of cored thicknesses of producing horizons the actual number of feet of screen set in the various producing zones was to be taken as the basis for arriving at the thickness of these zones and the "acre-foot" yields. It is obvious that in many instances only 20 ft. of screen, or even 10 ft. of screen, might be set in a well, when there might be actually 100 ft. of oil sand present. In the early operations in the Gulf Coast it was usual to set much less screen than the amount of sand. It follows that the "acre-foot yields" so arrived at would be much greater than those found by using the full amount of sand. In Mr. Teas' table, it was indicated that up to the end of 1933 "acre-foot" yields had been obtained in the several fields as listed in Table 1. A casual inspection of these yields will show that certainly they do not properly reflect the amount of oil produced from an acre-foot of the

Jan 1, 1936

Jan 1, 1936

By Wing G. Agnew

The drilling and bit-sharpening practice in the southwest Wisconsin zinc district generally conforms to the procedure described herein, except at very small properties, where drill steel is sharpened by hand. Though hot milling of rock-drill bits is practiced in South Africa on some of the large-scale operations, it is seldom seen at American minus in any form. Because of the simplicity and low cost of the equipment, it was thought that a brief description might prove interesting to same of the operators in ether districts who do not have enough steel to sharpen to warrant equipping an elaborate sharpening shop.

Jan 1, 1936

By J. G. Thompson

THE methods employed for the determination of oxides and oxygen in ferrous materials may be roughly classed in two groups, "wet" methods and "hot" methods, the first group including the iodine, electrolytic, mercuric chloride, hydrochloric acid, nitric acid, and chlorine methods; the second group including the vacuum-fusion and hydrogen-reduction methods. The wet methods depend upon preferential solubility in a selected medium to separate the metallic portion of the sample from the oxygen-containing constituents. Subsequent analysis of the insoluble residue permits the isolation and separate determination of individual oxides and compounds. The hot methods depend upon the reduction of the oxide constituents of the sample by means of carbon or hydrogen at elevated temperatures. With the exception of the recently developed fractional vacuum-fusion method, the hot methods do not identify individual oxides and compounds but yield only a single value represent-ing the sum of the oxygen contents of several or all of the oxide con-stituents present. With such diversity in the principles and. aims of the different groups, it is not surprising that concordance of results by differ-ent methods has usually been difficult to obtain. The present cooperative attempt to define more rigorously than has been possible heretofore the accuracy and limits of usefulness of the vari-ous methods, originated in correspondence between Dr. John Johnston, Director of Research of the United States Steel Corporation, and other interested metallurgists. The plan was, briefly, to submit identical samples to a number of laboratories for analysis by different methods and to collate the results of these analyses. The project was endorsed by the Iron and Steel Division of the American Institute of Mining and Metal-lurgical Engineers at the annual meeting in February, 1933, and has been conducted under the joint sponsorship of the Iron and Steel Division and the National Bureau of Standards. The latter organization undertook

Jan 1, 1936

By Gilbert Thiessen

The use of a pneumatic process for removing fine material (usually less than 48-mesh) is increasing in the preparation of stoker-size coal. The fine material, produced as a byproduct, is known as dedusting-plant dust. Since fusain is the most friable ingredient in bituminous coal (it may readily be rubbed to an impalpable powder with the fingers), it tends to accumulate in this byproduct. While studying the properties of cokes produced by blending Illinois coals with other materials, considerable quantities of fusain were required. Dedusting-plant dust suggested itself as a convenient supply. It became necessary, therefore, to determine how much fusain was contained in a measured sample of dust, how the fusain was distributed with respect to size and specific gravity in the sample, and whether or not it would be feasible or desirable further to concentrate or to recover the fusain from the dust before using it in the blends to be coked. The results obtained indicate the possibilities of production of a high-fusain material. Previous Work Lehmann and Stach have developed a processl,2 for separation of banded bituminous coals into their band ingredients by impact pulverization followed by screening or air separation. They found, as might be expected, that the fusain was concentrated in the very fine material. Prockat and Raute3 examined samples from dedusting plants operating in the Ruhr. They separated the dust into various screen sizes and determined the composition of each of these sizes in terms of the banded ingredients of the original coal. In the dusts examined by them, the finest material was always high in fusain, and most of the fusain contained in the original samples could be recovered from this fraction.

Jan 1, 1936