Search Documents

By Carl A. Zapffe, George A. Moore

IN a previous publication from this laboratory1 the conclusion was drawn that the embrittling effect of occluded hydrogen on iron and steel must result from the precipitation of the gas within small openings through the crystal structure. A review of the literature then published indicated the real existence of crystal sub- structures of the mosaic type and gave presumptive evidence that the "rift openings" associated with hydrogen occlusion are the same as the "disjunctions" of the mosaic theory. Inasmuch as no clear conception of the actual nature of the crystal fragments and openings inherent in these theories has been established, it was considered desirable to obtain direct micrographic evidence of their true configuration. In this direction the standard methods of metallographic attack have proved useless. Recourse was had, therefore, to the direct examination of the surfaces upon which failure by cleavage had resulted from the presence of hydrogen. It was expected that such a surface, un- affected by chemical attack and undistorted by polishing, would reveal the fine openings penetrated by the gas and thus indicate the real nature of the substructures. MATERIALS STUDIED In commercial steels, defects caused by hydrogen take various external forms ac- cording to such factors as structure and purity, and to the extent to which hydrogen either occludes or produces chemical changes. The present work relates only to the well-known transcrystalline hydrogen embrittlement-"pickling brittleness"-in which elemental hydrogen occluded within the grain develops cleavage characteristics. For example, hydrogen embrittlement resulting from hydrogen reaction products is excluded from detailed study. It was also desirable, as far as possible, to have the study uncomplicated by other elements which themselves cause brittleness. Three types of iron were used. These included ingot iron, decarburized free- machining steel, and a specially prepared, aluminum-killed, electrolytic iron. This , choice allowed a comprehensive selection of unavoidable minor impurities and inclusions, which could subsequently be shown to have no specific effects on the structures within the grains. Carbon, and any other impurities free to react with hydrogen, were first removed by a preliminary annealing treatment in hydrogen. Subsequent treatment in vacuo extracted much of this hydrogen and its gaseous reaction products. The resultant ductile iron was then embrittled either by a second anneal in hydrogen, followed by rapid cooling, or by cathodic electrolysis. Group I: Prepared from Armco Ingot Iron As shown in Table I, the principal impurity in this iron was oxygen, which survived the purifying treatment to a large extent. Two series were prepared. The first (Nos. SIO-24) was purified only one day in hydrogen and dehydrogenized one day in nitrogen. Containing both hydrogen and its

Jan 1, 1943

By John A. Ruppert, John E. Conley

Shortages of cinders, largely resulting from industrial plants converting to fuel-oil, together with an enhanced building activity, have seriously affected the cinder block and lightweight concrete manufacturers. In the search for other sources of lightweight aggregate, various clays, shales, slates and natural occurring lightweight rocks such as pumice, scoria, volcanic ash and the like have received special attention. Methods and equipment for producing suitable lightweight aggregates have been considered. In addition to an expanded use of the rotary kiln, the traveling-grate and continuous-sintering machines are being installed in many localities.

Jan 4, 1950

By F. M. F. Cazin

In my first paper, relating in general to the movement of solids in a medium, I stated a newly-discovered natural law, and explained its application to mechanical ore-concentration. This law, as applied primarily to the motion of ships in water, had been announced, demonstrated and defended by me in the Journal of the Franklin Institute for March, April and May, 1893, and has not been controverted since then. I therefore contented myself in my first paper with the simple statement of it; and in order to avoid unnecessary repetition, I refer the readers of this paper to that statement (ante, p. 81) and to the earlier publication already mentioned.*

Jan 1, 1895

By AIME AIME

A separate room in the suite occupied by the American Institute of Mining Engineers on the ninth floor of the United Engineering Society Building, has been equipped with furniture and telephone extension for the temporary use of members of the Institute or of sister societies, or visitors suitably accredited. In addition to this general accommodation, another room has been similarly furnished as a business headquarters for a single person, and for a limited period. For the conditions of this privilege, inquiry should be made at the office of the Institute. In order that the benefit of this arrangement shall not be restricted to a few members only, the period of continued occupancy will be limited, and applications will be considered in the order of their receipt. A small fee will be required for the use of the facilities furnished.

Jan 1, 1908

By F. P. Dewey

Rich Hill is situated in the famous car-wheel iron region of Southwestern Virginia, and although it contains many iron ores, this paper will be devoted chiefly to its car-wheel ore. Geologically, Rich Hill is somewhat difficult to describe, as the strata of the region are seriously folded and contorted. It lies at the base of one of the primordial spurs of the Blue Ridge, the ore appearing as a sedimentary deposit on the limestone No. 2, sometimes showing an imperfect stratification, but generally being an

Jan 1, 1882

By F. P. Dewey

RICH HILL is situated in the famous car-wheel iron region of Southwestern Virginia, and although it contains many iron ores, this paper will be devoted chiefly to its car-wheel ore. Geologically, Rich Hill is somewhat difficult to describe, as the strata of the region are seriously folded and contorted. It lies at the base of one of the primordial spurs of the Blue Ridge, the ore appearing as a sedimentary deposit on the limestone No. 2, sometimes showing an imperfect stratification, but generally being an

Jan 1, 1882

By S. N. Sharma, William Davis

Because of diminishing energy resources and rising energy costs, every industry is forced to carefully examine its pattern of energy consumption. The copper industry is no exception; current smelting practice begs for technological innovations that would improve the efficiency of its energy utilization. The thermochemical simplicity of copper metal production, as shown in Fig. 1, is deceptive. Designed from the same basic principles, there are four major commercial processes either in use or under construction; and others, such as the Mitsubishi process, are being developed.

Jan 5, 1977

By Luke L. Y. Chang, Bert Phillips

A number of molybdenum oxides have been synthesized and their crystal structures have been described.' No data have been published on the stabilities of these oxides nor on the phase relations in the system Mo-0. It is probable that the tendency toward oxidation of both the metal and the oxides with low oxygen content in addition to the high volatilization rate of the oxides with high oxygen content have precluded accumulation of reliable data for establishing phase relations. These problems make experimentation difficult, but a modifi-

Jan 1, 1965

By Ulick R. Evans, Maurice Cook

The structural changes in metals brought about by annealing follow-ing a deformation at a low temperature has been the subject of many investigations. No less than eleven metals and alloys have been studied in some detail; namely, aluminum, tungsten,2 iron,3 copperI4 gold, zinc,6 cadmium, tin: lead: brass,1° and cupronickel. As a result, it is possible to frame a qualitative statement of the effect of the degree of deformation and the temperature of annealing on the structure finally attained.

Jan 1, 1925

By T. T. Read

In discussing the taxation of mining enterprises, it is desirable to place limits of both time and space on the field of discussion. For our present purposes it seems best to limit consideration to taxation of mining enterprises in the United States, and to further limit the subject to taxation under approximately current conditions. Even with such limitations the field is large enough, since in this country we have, in most regions, a number of taxing powers; so that state, county and village tax systems must ordinarily be considered, in addition to our national or federal taxes. Nor is it possible, in discussing United States mineral taxes of today, altogether to pass by similar taxation in earlier periods, or related systems in other countries. It is perhaps hardly necessary to remind you, at the outset, that each age in the history of the world displays its own system of public revenues, and that the taxation systems of today are everywhere different from those of older times. Theories as to taxation have varied according to the economic basis of the society in which they were formulated, and our ideas as to justice in taxation fluctuate with changes in social conditions. The word taxation is used in a fairly definite sense today, but you have only to glance into the history of taxation to find that the paragenesis of ore deposits is a fairly simple subject as compared to the paragenesis of taxation systems.

Jan 1, 1932

By Charles A. Ashburner

[The statistics contained in this paper were collected for the United States Geological Survey and communicated to the Institute, by permission, prior to their publication in the report on the Mineral Statistics of the United States for 1887.1 The total coal-production of Alabama in 1887 was about 1,950,000 short tons, the spot-value of which, at the mines, was $2,535,000. The coal-regions of the State lie in the extreme southern part of the Appalachian coal-field, the northern part of which lies along the western New York-Pennsylvania State line; between these limits, New York on the north and Alabama on the south, portions of the

Jan 1, 1889

By Oliver Halston

THIS paper reports the results of the use of salt in some research work carried on during the past 3 years at the Salt Lake City Station of the Bureau of Mines, which is quartered in the University of Utah, whose Metallurgical Research Department cooperates with the Bureau. Only the work involving the use of salt is described. The authors wish equal credit given to J. F. Cullen, C. L. Larson, C. Y. Proutz, C. E. Sims, H. C. Neeld, R. W. Johnson, F. G. Moses, N. C. Christensen, and G. H. Wigton, who have all in some way contributed toward the success of this work. Lead Metallturgy Popularly Supposed to be Without Problems In bead metallurgy it is difficult at first to find metallurgical problems, as the prevailing conception has been that bead is so easily concentrated in its various ores and so easily reduced to its metallic form that the only progress possible is that involved in cheapening methods of mining and of reduction. Most of the problems usually considered are of minor nature and do not involve radical metallurgical changes. During the 3 years of work of the Salt Lake Station, the following classification of problems in the metallurgy of bend has been made: Those involving Oxidized Ores. 1. Ores containing only bead. s. Ores containing bead and silver or gold. 3. Ores containing bead and zinc, with or without silver. Sulphide Ores. 1. Ores of pyrite carrying some bead. 2. Ores of complex zinc-bead-iron sulphides. 3. Complex sulphides containing in addition precious metals.

Jan 8, 1917

By A. Patton

Introduction THE use of roll scale in the Bessemer process dates back, to the "best of our knowledge, at least 20 years. It was first used by the Ohio Steel Co.; Youngstown, Ohio (now the Ohio Works of the Carnegie Steel Co.) under the direction of Sam, MacDonald, Superintendent of the Bessemer Department at these works. Two 10-ton vessels and one blowing engine capable of blowing one heat at a time were employed. The object of using the scale was to -shorten the length of the blow; or in other words, to increase the production with the same equipment. Various means were tried out for introducing the roll scale into the bath of molten iron: It was shoveled into the vessel before the heat was charged, so that the metal would flow over the scale; it was shoveled into the bath after the vessel was turned up; it Was dumped into the empty iron ladle by the wheelbarrow-load, and at times wars dumped on top of the molten metal in the iron ladle. But the practice of introducing the scale into the iron ladle had to be abandoned on account of danger from explosions and of skulling the -ladles. It was soon learned that the proper place to charge the scale was in the empty vessel, so that when the molten iron was poured into the vessel it flowed over the scale, causing a considerable reaction to take place before the heat was turned up. Eventually, cylindrical chutes similar to those now in use were installed. Into these chutes the scale is dumped and carried into the empty vessel. Before this convenient means of introducing the scale was adopted, the Ohio Works had satisfactorily demonstrated that roll scale would increase production, by blowing 107 heats in one 12-hr. turn (1,087 tons) with one blowing engine, blowing one heat at a time; whereas, prior to the use of scale, the best practice at these works was about 80 heats under the same conditions.

Jan 2, 1917

By William P. Blake

I have not before had the honor of offering to the Institute a communication on the subject of the variety of asphaltum which I described as uintahite; but several disconnected notices of it have appeared in the Transactions, and much additional information regirding it and its relations to other varieties of the asphalt group has been gathered together. Dr. Henry Wurtz has also discussed the nature of uintaite, and has endeavored to show that it should be considered a variety of grahamite.* We have also had an interesting paper upon."Asphalt and its Uses," from Captain F. V. Greene, containing much important technical information and a scheme of classification of the varieties of bitumen and of bituminous compounds. The object of the present paper is to bring the substance of these disconnected notices together; to present some additional facts; to revise the name uintahite; to compare the substance with the allied bitumens or asphalts, known as albertite and grahamite; and fur-

Jan 1, 1890

Jan 1, 1902

By H. H. Stoek

The fundamental reasons underlying the choicc of a method of mining a coal seam are safety of operation, cheapness of producing the coal and the character of the product as a saleable article. From the standpoint of safety, open or strip coal mining is always preferable, as many of the dangers inherent to underground work are absent, such as explosions of gas and dust, falls of roof and coal, and also to a great extent those due to haulage and the use of explosives, thus eliminating three of the chief causes of accident from which about 75 per cent. of the underground accidents in coal mines occur. The conditions under which coal is stripped also make the work much safer than ordinary quarry work, as the depth of the pit is usually comparatively small. Prom the standpoint of low mining cost, there is much misapprehension and many of the costs given are misleading in that they do not take into account such items as the destruction of the surface for future use, the full cost of the removal of the overburden, depreciation, amortization, coal depletion, loss of time through floods and from bad weather in winter, etc. Coal is no doubt often put on the cars at less cost by stripping than by underground mining, but by no means always so, as is too generally assumed. In some cases coal must be obtained by stripping or not at all, because the small amount of overburden renders underground mining impossible.

Jan 1, 1918

By John Richards

MY remarks will be confined to the experience of our company in mining the No. 8 seam of coal in Ohio, although I believe that the relationship existing here between the method of mining and the method of cleaning will hold true in many of the coal seams throughout the country. The increasing demand for a cleaner and better graded product is being felt throughout the entire coal industry, and the methods of mining are playing an important part in the control of various sizes and quality of coal produced. We have found a definite relation between the mechanical loading of coal and its preparation for the market. In the No. 8 coal seam the location of the non-combustible material is regular. The' marketable coal lies in three benches, separated by streaks or bands of impurities. These impurities must be removed from the coal to properly pre pare the product for the market. Where hand-loading methods are employed, the loader removes as much of this non-combustible material as possible at the working face. The impurities that are missed by the loaders are removed as the coal passes through the preparation plant, by means of picking tables. As this method of cleaning cannot improve the quality of the extremely fine sizes, a practice has been established in the company's hand-loading mines, of undercutting the coal about 2 in. above the bottom of the seam, thereby eliminating any possibility of impurities caused by the cutting machines cutting into the rock bottom below the coal seam.

Jan 1, 1934

By Arthur Wilson, Frederick Carr

INTRODUCTION 1. The application of retreat longwall mining to the North American coal mining conditions is becoming more advantageous as more experience is gained. The productivity results being achieved and potential possible illustrates that this system can be keystone of future underground coal production. 2. In the American coal fields multi-entry is normally practiced as this allows profitable longwall development with existing equipment and systems. Difficulties are being experienced however in the longwall retreat phase by the collapse of multi-entry roadways and excessive use of supplemental support in the following panel tailgates. In some instances the headgate of an operating face can also be in difficulty. 3. Jim Walter Resources Mining Division is developed on a mining plan that calls for three retreat longwalls at each of its four deep mines which have varying depths of cover and immediate roof and floor conditions. The 63 Mine has experienced longwall entry difficulty and there were differing viewpoints with respect to the best development systems to adopt particularily regarding the number of entries and pillar sizes. In an attempt to reconcile these different points of view J.W.R. asked Dr. Wilson to examine the problem and this paper outlines the new approach developed.

Jan 1, 1983

By Richard S. McCaffery, Morrison B. Yung

While assaying some copper carbonate ore from the Frazer claims, Similakameen, B. C., I noticed that on parting the gold button a deep orange solution was formed. The button gave off pink bands in the nitric acid, which became deep orange at a short distance from it; and as it traveled over the surface of the porcelain dish, it left a deep orange track behind. As the button brightened in the cupel, it appeared to have a bronze color; but I have since found that when amarillium is in large excess of the gold, the button is a very dark gray. The button parted easily. To the orange solution I added a salt (NaCl) solution, shook in a silver testbottle, and filtered. With H2S I obtained a precipitate, which I supposed due to platinum. However, on further tests, it did

Jan 1, 1903

By R. G. O’Meara, S. M. Runke

THE Bureau of Mines has been charged by Congress to investigate processes for the production of alumina from low-grade bauxite, alunite, and clay. As one part of the program, an investigation of the application of ore-dressing methods to improve the grade of high-silica bauxite is in progress at the Mississippi Valley Experiment Station at Rolla, Mo. This paper summarizes data obtained so far and presents detailed results of tests on four typical samples. MINERALOGY OF BAUXITE The name bauxite originally was used to designate the dihydrous aluminum oxide (A1203.2H20). The designation has been retained, although the existence of a specific mineral of such composition has been disproved. The term is now applied to ores of aluminum consisting of various mixtures of the minerals gibbsite (A1203.3H20), diaspore (A1203.H20), and boehmite (A1203.H20). The predominant hydrous aluminum oxide in most American bauxite, however, is gibbsite. In some instances bauxite may be amorphous mixtures of the hydrous aluminum oxides that approximate the composition of dihydrous aluminum oxide (A1203.2H20). The proposed name for this material is cliachite. Gibbsite and boehmite, the trihydrate and monohydrate, are soluble in a solution of sodium hydroxide at elevated temperature and pressure, whereas diaspore is practically insoluble. The solubility of these two minerals is the basis of the Bayer process of alumina extraction. All bauxites contain certain impurities, the commonest of which, in the order of their importance, are: silica, principally as a constituent of kaolinite, and to a lesser extent as quartz; iron, as hematite, limonite, and siderite; and titanium, as ilmenite, rutile and leucoxene. Minor impurities are zircon, cobalt and nickel. Bauxite is produced commercially in Arkansas, Alabama, Mississippi, Georgia and Tennessee, but the most important deposits in the United States are in Arkansas, in the vicinity of Little Rock. HISTORY OF BAUXITE BENEFICIATION The literature on bauxite beneficiation is limited, but the reports of Gandrud and DeVaney1 and Clemmer, Clemmons, and Stacy2 show the possibilities of flotation as a means of beneficiating bauxite. Their work has also developed reagent

Jan 1, 1944