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By W. B. Heroy

ONLY through the mineral fuels can large amounts of energy be transported to great dlstances and stored for long periods for future use. Coal has the advantages over oil of greater safety of handling and smaller losses in storage. But oil is, in the present stage of technical advancement, the more economical source of liquid fuel for internal-combustion motors. No method for direct use of coal in such motors has been developed that can compete with petroleum products. The automoblle engine and the airplane motor are designed to make the most effective use of gasoline.

Jan 1, 1944

By AIME AIME

THE MILLING PROGRAM on Monday required a morning and afternoon session with a special luncheon of the Milling Committee in the Engineers Club at noon. Grinding and flotation were the main subjects of the papers which drew an attendance of fifty or more at each session. Under the direction of Chairman Arthur F. Taggart in the forenoon, all papers on flotation and general milling were considered, leaving the, after- noon free for crushing and grinding, with Dr. Galen H. Clevenger in the chair. The high spot was the first public presentation of the idea of size reduction of minerals by explosive shattering.

Jan 1, 1932

By C. K. Leith

CERTAIN ideas on iron and steel sanctions to follow originated in a series of conferences held under the joint auspices of the War Department and Brookings Institute in Washington last spring. The views presented may be regarded as those of substantial segments of the steel industry. In view of the fact that steelmaking capacity can be so quickly converted to the production of armament, any effective control must necessarily include the entire steel industry and not solely the parts devoted to the production of implements of war. It must also be exercised all the way from production and shipment of raw materials through their ultimate conversion into finished products and use. Control will be dis- cussed under two main headings: (I) control of raw materials at the source; (2) control of steel capacity within the Axis countries.

Jan 1, 1944

By Carl Zapffe

THE object of the Bradley process is to free manganese oxide from its associated gangue and separate the contained iron oxide by dissolving the manganese and precipitating it from the solution. 'The fundamental features of the process are : making. both 1 a manganese ore and an iron ore; effecting a separation of manganese .and. iron by means of selective roasting; leaching- the manganese from the roasted ore by using ' ammonium sulfate; precipitating the manganese by using the ammonia gas generated during leaching; fixing the precipitate by oxidizing with air; breaking down and reforming the ammonium sulfate, so that daily very little additional ammonium sulfate beyond that originally charged into the system is required; washing the manganese precipitate and the iron-silica residue and evaporating the liquor to conserve the dissolved salts in the moistures of these two products and 'to reduce the sulfur content,; drying the precipitates; magnetic wet-concentration of the iron-silica residue; sinteriny the manganese-and .the' iron-concentrates.

Jan 1, 1929

By AIME AIME

S ULFURIC acid made in the United States during the last four years has averaged approximately 7,000,000 tons of 50" B6 acid a year. This is double the production of the year 1913. About 66 per cent of the acid is made from sulfur, 16 per cent from pyrite, 13 per cent at copper, lead, and zinc smelters, and the remainder from miscellaneous sources it her the chamber process or the contact process, (at some plants both) is used. In 1923, the contact process accounted for nearly 30 per cent of all the sulfuric acid made in this country and since then it has been increasingly employed. It was first introduced here in 1898, and has always .proved less expensive than the chamber process for the manufacture of .acid of high concentration and purity, but the latter produces acid of low strength suitable for many industries.

Jan 1, 1929

By Franklin G. Pardee

IN 1920 the Minnesota Tax Commission estimated a reserve of 1,341,674,538 long tons of iron ore in Minnesota, the Michigan State Tax Commission report showed 199,092,855 long tons in reserve in that state, and the Wisconsin Geological Survey set the Wisconsin reserves at 21,500,000 long tons. The total reserve that year for the Lake Superior District amounted to 1,562,267,393 long tons. Ten years later the reserves of iron ore in these same districts were Minnesota 1,235,227,510, Michigan 168,349,823, and Wisconsin 23,000,000, or a total of 1,426,577,333 long tons. The decrease in ore reserves in this ten-year period was 135,690,060 long tons, but the shipments were 520,746,975 long tons. In other words, the ten-year depletion in reserves was only 8.68 per cent. If similar conditions carry into the future this calculation would indicate a life for the ore reserves of the Lake Superior region of over 100 years.

Jan 1, 1933

By Charles H. White

METHODS in colorimetry are based on the assumption that the intensity of the color of a definite volume of solution is directly proportional to the quantity of the color-producing substance' present. In the preparation and examination of colored solutions there are three ways in which the depth of color may be varied. These variables are; (1) the quantity of the coloring matter, (2) the quantity of the solvent, or the dilution, and (3) the thickness or depth of that portion of the solution examined. With these three variables as a basis, three general methods in colorimetry have been devised, all of which have been used in the determination of carbon in steel. In the first method, the quantity of the solution is kept the same for both the unknown steel and the standard, and the sections compared are of equal thickness, while the quantity of the standard is varied until the color obtained is of the same intensity as that produced by a definite quantity of the unknown steel. In laboratories where this method is used there is pre¬pared and kept for permanent use a series of solutions with varying amounts of the standard, representing the percentages of carbon from the lowest to the highest demanded in that laboratory. These standard solutions are kept in bottles, or test-tubes of equal diameter, and are arranged in series from the faintest to the most intense color, so that it is a simple matter to find the place of the unknown steel in the series, when the solution is of a definite volume and is contained in a tube of the same diameter as the standard tubes. In the second method, equal quantities of the standard and of the unknown steel are dissolved, the standard is diluted to a definite volume, and the solution of the unknown steel is di-

Sep 1, 1906

By Frederick M. Becket

AFTER all the chronology that has been given, what is the present status of chromium steels? For the purpose of this discussion the different types of chromium steels can be divided into three classifications-those containing relatively low , percentages of chromium, say 5 per cent or less; the medium-chromium steels containing up to about 18 or 19 per cent chromium; and the steels containing still higher percentages of chromium, and some of the special alloys. Chromium has some unique effects in steel, so it is well to make a few generalizations. The affinity of chromium for carbon is great and the metal is unique in the manger in which it supplements and enhances the effects of carbon. Chromium retards -considerably the thermal transformations on cooling and exerts an opposing influence both on the absorption and precipitation of the carbides in steel. These statements make it easy to understand the fact that chromium .steels are capable of producing a hardened product at a much slower rate of cooling than is, true of plain carbon steel, and that chromium carbide or -the mixed carbides of iron and chromium do not contribute to brittleness to as great a degree as does iron carbide.

Jan 1, 1929

By James P. Kimball

AMONG the curious results of the recent advance of prices in the iron trade of the United States, one of them at least is to be regarded as of great importance. I allude to the utilization of mill cinder as a cheap and almost costless substitute for high-priced iron ores in many blast furnaces, situated within easy reach of such raw material. It has been, with but few exceptions, the practice in this country, based upon tradition rather than upon authority or European precedents, to waste this material on 'account of its high proportion of silicic and phosphoric acids, although known to contain more iron than most ores, and although also known to be sometimes applied to the blast furnace in greater or less quantities without serious detriment to the iron for specific purposes. While in use to a limited extent in the Hocking Valley and Hanging Rock iron regions of Ohio for several years, its use in Western Pennsylvania has only become general of late, under the exigencies of high prices and a short supply of ore. Especially has mill cinder largely entered into the stock of furnaces attached to rolling mills in and about Pittsburgh. Under such circumstances the cinder pig has been paddled on the premises, and the malleable iron produced has been unexpectedly good. Cautiously as at first mill cinder has been applied, it is evident that the temptation to use it freely is a strong one whenever the commercial rates for high-class ores are out of proportion to the general conditions of the iron trade, as sometimes happens in this country, especially as the free use of it is apparently justified by the quality of the iron produced from this cheap and abundant material. Indeed the consumption of cinder pig has., not been wholly confined to mills using up the production of furnaces belonging to the same plant. One furnace at least on the Ohio, at Covington, for several' months has been making foundry pig from "all cinder." The iron has gone into the general trade. It is probable that malleable iron of good quality can he made from the poorest cinder pig, but with what degree of economy will

Jan 1, 1881

By Andrew A. Blair

The increased importance and value of chemical analysis in connection with metallurgical operations is largely, if not entirely, due to the increased accuracy of the analytical methods used for the quantitative determination of the foreign elements always associated with the metal operated upon. This applies especially in the working of iron and steel, and to the determination of the amounts of such elements as phosphorus, carbon, and silicon. The influence of greater or smaller amounts of these elements upon the physical properties of iron and steel will be better understood when the proper experiments shall have been made upon samples whose chemical composition is known with almost absolute certainty. From the present standpoint of analytical chemistry, it is easy to see that at least one reason for the failure of many attempts to solve this problem, is the inaccuracy of the analytical methods used. Even at the present time the frequent want of agreement (over and above the unavoidable error due to manipulation) between chemists working on the same sample, leads one to think that there is still at least a choice in the methods used. It is true that very frequently a faulty method in the hands of a skilful analyst may be made to give corroborative results

By Edward D. Thimons, Richard J. Kline

Converting the energy of falling water into useful work is a well developed engineering concept. Much of the electric power consumed in the United States is generated in this manner. It is easy to conceive that the water which flows down long vertical pipelines into deep nines could be utilized in a similar manner by allowing it to operate a turbine at the bottom of the pipelines. The mines in the United States are continually descending to greater depths in search of mineable deposits. Large quantities of water are carried down long vertical pipelines in order to be used for dust suppression, motor cooling, and refrigeration. Pumping the used water back to the surface is also required. The electrical costs associated with mining are also constantly escalating due to both increased demand and rising kilowatt hour costs. To help deal with this problem, the United States Bureau of Mines (USBM) has awarded a contract to Foster-Miller, Inc. of Waltham, MA, to investigate, evaluate, and demonstrate commercially available means of energy recovery for the deep mining industry. In other words, it demonstrates an efficient system for converting the energy of water flowing down vertical pipelines into useful mechanical or electrical energy.

Jan 1, 1982

By Andrew A. Blair

THE increased importance and value of chemical analysis in connection with metallurgical operations is largely, if not entirely, due to the increased accuracy of the analytical methods used for the quantitative determination of the foreign elements always associated with the metal operated upon. This applies especially in the working of iron and steel, and to the determination of the amounts of such elements as phosphorus, carbon, and silicon. The influence of greater or smaller amounts of these elements upon the physical properties of iron and steel will be better understood when the proper experiments shall have been made upon samples whose chemical composition is known with almost absolute certainty. From the present standpoint of analytical chemistry, it is easy to see that at least one reason for the failure of many attempts to solve this problem, is the inaccuracy of the analytical methods used. Even at the present time the frequent want of agreement (over and above the unavoidable error due to manipulation) between chemists working on the same sample, leads one to think that there is still at least a choice in the methods used. It is true that very frequently a faulty method in the hands of a skilful analyst may be made to give corroborative results

Jan 1, 1876

By G. Hasenfus, M. Karmis, G. Goodman

Surf ace subsidence is rapidly becoming an important environmental consideration of active as well as abandoned mining operations. The damages attributed to this phenomenon have been witnessed in both rural and urban areas and include land settlement and fracturing, structural damages to surface buildings or facilities and disruption or contamination of ground water supplies. The problem of mining subsidence has gained considerable emphasis in the Appalachian coalfield. The increased mining activity over the past few years and the particular topographic conditions, lithologic and structural environment, mining methods and hydrological patterns are all factors which have contributed to specific subsidence characteristics in this region. The objective of this paper is to discuss and review the most widely accepted methods of subsidence prediction above longwall as well as partial extraction systems in Appalachia. These include an accurate and easy to apply empirical method, which has been developed entirely from field information pertaining to the Appalachian coalfield and incorporates both geometrical and geological information of the panel in question. The second method is a development of influence functions and is founded on the zone area approach. Both methods, originally derived for longwall mining, have been expanded to include room and pillar applications and have been widely used by the mining industry in the Appalachian coalfield.

Jan 1, 1984

By W. B. Potter

There is probably no more interesting group of mineral fuels to be found in any country than that occurring within the limits of the new State of Colorado. The supplies are so abundant, and the occurrence and distribution are so favorable for easy development and transportation to the future manufacturing centres of the State, that they are destined to play a very important part in the material growth and prosperity of the region, the more so because of the rich and varied stores of ores awaiting metallurgical treatment, and the comparative scarcity of timber for fuel. From a purely scientific point, also, these lignitic coals form an interesting and important series. An examination of their geological occurrence and relations opens up new and important questions regarding the comparative value of various kinds of geological evidence, while a study of the character and composition of this class of fuels, which forms a connecting link, as it were, between the lignites and the true bituminous coals, may lead to a more thorough and accurate classification of mineral fuels. The analyses here presented are from samples, of not less than fifty pounds each, obtained by myself during the summer of 1875, and may be regarded as representing very fairly the average run of

By D. M. Jamieson, M. P. Pearse, E. R. A. Plumstead

In 1948 the shaft sinking record in the Republic of South Africa was held by the Van Dyk Consolidated Mines Ltd. for a ventilation shaft with a footage of 461 ft sunk during the month of August 1941. This record remained for some ten years; but in the ensuing nine years it was broken no less than 13 times. Table I gives shaft sinking records throughout the world for the 21 years, 1940 to 1960. History shows that the wide, deep, timbered rectangular shaft had passed its peak of popularity by 1948, although it still had a great deal to commend it, both from the sinking and operational points of view. In sinking, it is easy to clean manually, and water can be handled by bailing when wet ground has to be negotiated; its shape also lends itself to equipping concurrently with sinking. In operation it provides the most convenient "in line" hoisting arrangement, and if the ventilation requirements so demand, it offers the simplest solution in that it can be divided into upcast and downcast sections. Furthermore, in the case of a multi-level mine, the shaft compartments can be reduced conveniently if the full area of the shaft is not required to serve all levels.

Jan 4, 1963

By W. B. Potter

THERE is probably no more interesting group of mineral fuels to be found in any country than that occurring within the limits of the new State of Colorado. The supplies are so abundant, and the occurrence and distribution are so favorable for easy development and transportation to the future manufacturing centres of the State, that they are destined to play a very important part in the material growth and prosperity of the region, the more so because of the rich and varied stores of ores awaiting metallurgical treatment, and the comparative scarcity of timber for fuel. From a purely scientific point, also, these lignitic coals form an interesting and important series. An examination of their geological occurrence and relations opens up new and important questions regarding the comparative value of various kinds of geological evidence, while a study of the character and composition of this class of fuels, which forms a connecting link, as it were, between the lignites and the true bituminous coals, may lead to a more thorough and accurate classification of mineral fuels. The analyses here presented are from samples, of not less than fifty pounds each, obtained by myself during the summer of 1875, and may be regarded as representing very fairly the average run of

Jan 1, 1877

By Luther Wagoner

For a number of years I have, at odd times, tried to perfect a method of assay sufficiently delicate to find and estimate minute quantities of gold and silver. The object in view was to examine rocks remote from veins or mineral areas, in order to test the probability of the lateral-secretion theory. Having succeeded in measuring approximately the amount of gold and silver contained in one cubic centimeter of sea-water, I present a detailed account of the method employed, with some of the results obtained. General Method of Assay. The use of purified lead without other flux, blowpipe methods, extraction by cyanide, and measurement of the beads by the microscope. Purged Lead. The method of testing is by cupellation. On a properly prepared cupel, it is easy to cupel and find a bead of 0.002 mm. diameter. Such a bead of silver weighs about 1 part of a milligramme. A bead 0.02 mm. in diameter weighs about 1/24,000 mg., and a close approximation can be made to its weight. It is desirable that the lead used in the assay should be low in silver so as to avoid large correction, but as the parted

Jan 1, 1902

By B. H. Bergstrom, Will Mitchell, T. G. Kirkland, C. L. Sollenberger

SEVERAL constructive and fundamental studies have been made in the analysis of data obtained from experiments carried on with batch ball and rod mills. The operating characteristics of ball milling in small continuous circuits have also been appraised. It is from these analyses that some of the theories of comminution have been developed. Relatively few studies of continuous rod milling have added significantly to the fundamental concepts, because seldom have they yielded sufficiently consistent results. Perhaps they have been too limited in their scope. Careful control of the variables in batch grinding is simple compared with that encountered in a continuous operation. This factor alone has discouraged many investigators. Occasionally results of systematic changes made in industrial rod mill circuits have been published, but usually the data are sketchy and are restricted because -of the unwieldiness of the equipment used. The work, in general, has not been comprehensive; nevertheless it has provided empirical relationships that have bridged the gap between postulate and practice so that by proper manipulation of formulae, a mill designer can anticipate mill size and power requirements.1-3 Although operating variables of a small continuous mill are not so easy to control as with the batch mill, with present day devices, and with careful experimental work, consistent results can be obtained.

Jan 10, 1954

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. SOURCES The principal sources of the gas at present are coke ovens, lime kilns, breweries and other fermentation plants, all of which are within easy reach of markets. Natural sources, however, have not received the consideration they merit, mainly because of their isolation. It is asserted by some manufacturers that the carbon dioxide gas produced from wells is unsatisfactory because it often contains impurities that are difficult to remove, while that produced as a byproduct is much purer or contains impurities that are easier to remove.

Jan 1, 1936

By E. Goldin, H. J. Juretschke

THE electrical properties of porous conductors have been studied ever since such materials, usually prepared by pressing and sintering of metallic powders, obtained practical importance. In most cases, however, the results have not been easy to interpret because of the great number of independent variables such as powder size, pressure, pressing rate and temperature, subsequent thermal history, porosity, and so on, which enter into the fabrication of industrially desirable materials. In recent years an interpretation of these properties has become of interest because the electrical properties of many new substances, prepared as fine powders by crystallization from the vapor phase or by reactions in the solid state at high temperatures, have to be determined on porous samples formed from the powder. Since theoretically significant information must refer to the fully dense state of the material, it is important to relate the electrical properties measured on such porous samples to those expected for a sample of 100 per cent density. A simple theory for the porosity dependence of the electrical conductivity and the Hall effect was recently proposed by Juretschke, Landauer, and Swanson.' Their model, assuming a distribution of pores of equal size and shape, sufficiently far apart so that each pore is embedded in a region of uni-

Jan 1, 1959