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By T. J. Bosworth

The effect of hydrogen pretreatment of alumina, magnesia, and zirconia crucibles on reduced oxygen levels in iron charges has been studied. Hydrogen treatment of commercial high-purity magnesia crucibles was observed to produce as high as 70 pct reduction in oxygen content in iron melts. Hydrogen treatment of the commercial high-purity grade zirconia crucibles produced a 25 pct reduction in oxygen levels in iron melts. An average reduction of Knoop hardness of 47 pct was recorded on the iron charges melted in hydrogen-treated crucibles. On the basis of the experiments and the free-energy diagram, it appears that the major source of reducible oxygen to the iron charge is the suboxides and impurity oxides rather than the major oxide of the crucible. Suitable pretreatment of the crucibles to reduce and remove these oxides yields low oxygen levels in iron melted in the crucibles. DURING the last decade, attempts to produce more pure and uniform alloyed metals have brought about the development of many new melting techniques. Notable among these are vacuum-induction melting, inert and consumable-electrode melting, the cold-mold technique, and numerous techniques for removal of impurities by chemical reaction. However great the achievements in this field, metals must still be melted in contact with media of varying reactivity; i.e., gas, ceramic, and slag. Studies have been made to attain an understanding of the reactions that take place during melting, including slag-metal reactions and equilibria, equilibrium of hydrogen and water vapor, and carbon dioxide and carbon monoxide with oxygen in molten iron. These reactions have been treated quite thoroughly. There is one condition, however, that has been widely overlooked, and, to the author's knowledge, only cursive investigation has been made of it. This is the reaction between the ceramic crucible material and the iron charge. In recent years, Hadley and Bianchi' made a series of studies on hydrogen deoxidation of iron in magnesia crucibles. Bianchi2 studied crucible-FeO equilibria in the temperature range 1525°to 1650°C in high vacuum with, however, inconsistent results. Richardson and Jeffes3 in their series of articles on thermodynamic reactions in the making of iron and steel refer to Wentrup and Hieber's4 work on iron and aluminum deoxidation. Their pork included melting iron in alumina crucibles and measuring the aluminum and oxygen content in the iron. Because of the low values obtained, question has arisen of their analytical accuracy.3 Dastur and chipman5 obtained values on hydrogen-oxygen equilibrium in molten iron contained in alumina crucibles similar to those obtained in experiments in the present program. Hochmann6 studied removal of impurities in chromium irons in high vacuum. His results with respect to oxygen level in chromium-iron melted in magnesia crucibles are consistent with results we have obtained.

Jan 1, 1959

By Howard A. Meyerhoff, J. Earl Frazier

It is not known when silica sand was first noticed along the north coast of Puerto Rico, but the first mention of its occurrence was made in 1922, by N. L. Britton,1 who described its presence in isolated patches extending from Loiza westward beyond Manati. Further observations were made in 1925 and 1926 by Meyerhoff,2 who extended the known occurrences still farther westward to the low hill belt in the Quebradillas limestone immediately south of Hatillo. The extraordinary purity of the sands, which in most localities exhibit no contamination from the non-siliceous materials surrounding them, was quickly appreciated, and the feasibility of utilizing them for the manufacture of glass was investigated, initially by the Committee on Mineral Resources3 and later (1936) by the Puerto Rico Recon-structionAdministration and by H. C. Ray, mining engineer of the Insular Bureau of Mines. In 1934 samples submitted to the Hazel Atlas Glass Co., of Washington, Pennsylvania, were reported to have the composition as shown in the table on column two. Appreciation of the quality of the sand prompted geological and quantitative studies of the deposits, as well as cornmercial investigations to determine the feasibility of utilizing it locally or on the mainland for the manufacture of glass containers. Distribution of the Sands The quartz sands consistently lie within the outcrop area of the Quebradillas limestone, the youngest of the Miocene formations in the Tertiary coastal plain that fringes the northern coast of the Island. Many of the deposits are closely associated with limestone outcrops, but some appear to be embedded in lagoonal sediments at some distance from rock exposures, and at least one deposit, near Dorado, has been reworked by waves and littoral currents. With this single known exception, the deposits consist of irregular, patternless patches of white sand, which have sharply defined contacts with the surrounding material. Although patches of sand are present in a 90-km. belt that is not more than 5 km. wide, extending from Loiza to Hatillo, they attain maximum size, purity and number in the north central coastal area between Dorado and Barceloneta. Fifty separate deposits have been mapped in Lago Tortuguero and to the south of it, some as small as 50 ft. in diameter but

Jan 1, 1948

By J. Earl Frazier, Howard A. Meyerhoff

It is not known when silica sand was first noticed along the north coast of Puerto Rico, but the first mention of its occurrence was made in 1922, by N. L. Britton,1 who described its presence in isolated patches extending from Loiza westward beyond Manati. Further observations were made in 1925 and 1926 by Meyerhoff,2 who extended the known occurrences still farther westward to the low hill belt in the Quebradillas limestone immediately south of Hatillo. The extraordinary purity of the sands, which in most localities exhibit no contamination from the non-siliceous materials surrounding them, was quickly appreciated, and the feasibility of utilizing them for the manufacture of glass was investigated, initially by the Committee on Mineral Resources3 and later (1936) by the Puerto Rico Recon-structionAdministration and by H. C. Ray, mining engineer of the Insular Bureau of Mines. In 1934 samples submitted to the Hazel Atlas Glass Co., of Washington, Pennsylvania, were reported to have the composition as shown in the table on column two. Appreciation of the quality of the sand prompted geological and quantitative studies of the deposits, as well as cornmercial investigations to determine the feasibility of utilizing it locally or on the mainland for the manufacture of glass containers. Distribution of the Sands The quartz sands consistently lie within the outcrop area of the Quebradillas limestone, the youngest of the Miocene formations in the Tertiary coastal plain that fringes the northern coast of the Island. Many of the deposits are closely associated with limestone outcrops, but some appear to be embedded in lagoonal sediments at some distance from rock exposures, and at least one deposit, near Dorado, has been reworked by waves and littoral currents. With this single known exception, the deposits consist of irregular, patternless patches of white sand, which have sharply defined contacts with the surrounding material. Although patches of sand are present in a 90-km. belt that is not more than 5 km. wide, extending from Loiza to Hatillo, they attain maximum size, purity and number in the north central coastal area between Dorado and Barceloneta. Fifty separate deposits have been mapped in Lago Tortuguero and to the south of it, some as small as 50 ft. in diameter but

Jan 1, 1948

By R. V. Ramani, T. V. Falkie, T. E. Wilson

In order to increase the efficiency of underground coal operations, it is necessary to understand not only the operating system in detail, but the interrelationships between system components and the operating environment. With such an understanding comes more exact application of simulation and other operations-research techniques to plan and operate mining systems. One aspect of the coal-winning system in need of better definition, namely, the performance of continuous miners, is dealt with in this paper. Detailed discussion of this research will be found in a report by the authors. Mining Rate The performance of continuous miners-that is, the rate at which miners can deliver coal from an underground face to the outby transportation system-is dependent upon the geometric and geological conditions of mining, the characteristics of the mining machinery, and the skill of the machine operators. In order to predict mining performance, it is necessary first to identify these factors, secondly to devise a data-collection technique, and lastly, to select a method of data analysis for drawing meaningful conclusions. Factors Affecting Mining Rate: The factors that affect the mining rate can be conveniently grouped in the following four categories: Geological Factors-The natural conditions such as seam thickness, hardness, and cleavage. Geometrical Factors-The height and width of the entries and the angle of drivage with respect to the main entries. Machine Factors-The mechanical characteristics and physical dimensions of the machine, condition of the machine, condition of the bits, and related items. Other Factors-Operator efficiency, size consist of cutter product, etc. A classification such as given here is not rigid; some of the factors can be included in more than one of the categories and some can be combined as ratios. Data Collection The empirical nature of this investigation required measurements of variables under operating conditions in underground coal mines. A majority of the variables measured were continuous over a specific range of values; for example, the "width ratio" varied in practice from 0.25 to 1.00. "Dummy" values were assigned to certain operational variables in order that the variables would have numerical expression, i.e.: [ ] Data Analysis The method of analysis was to test a large model containing potentially significant variables and then reduce the model to one containing only the essential significant variables. The procedure of "scanning" a large proposed model and subsequently condensing the model consisted of two cycles of the same series of computational procedures. Correlation analysis, factor analysis, and regression analysis were the three statistical procedures that were used to derive the rate-generating equation. Correlation and Regression Analysis: Multiple linear correlation coefficients between all of the variables were calculated using the Pearson product moment formula along with the statistical significance of the correlation

Jan 1, 1975

By William B. Harris, Leonard Greenburg, Gustav Werner

Haulage in tunneling operations generally has been done with electric locomotives. As a rule, on short hauls the source of electricity is a storage battery mounted on the locomotive, which, of course, must be removed and recharged periodically. Where the distance from the recharging point to the tunnel face is very long, and where loads are heavy, trolley-driven locomotives are used. Diesel engines have been used in mining and tunneling operations in Europe for a number of years. The recent reports of studies in Belgium1 and by the Bureau of Mines in this country2-4 have indicated the potentialities of this form of power for haulage, mucking, bulldozing and many other underground operations. The hazards attending the use of Diesel engines in more or less closed spaces have long been known. The exhaust constituents that may create a harmful or objectionable environment are carbon monoxide, oxides of nitrogen and sulphur, carbon dioxide, aldehydes and smoke. Lack of precise information regarding the concentration of these gases and the ventilation requirements to reduce them to safe levels has to some extent suppressed their general acceptance in tunneling and mining work. Not until the work of the Bureau of Mines referred to above, and certain experience gained in the construction of the Delaware Aqueduct, ‡ has there been available the requisite information regarding the conditions under which their use may be permitted. This paper concerns itself with the successful operation of Diesel engines underground in the construction of certain parts of the Delaware Aqueduct, and describes the conditions under which Diesel engines have been found to operate with a minimum production of noxious gases. The test data reported were obtained during the operation of Diesel engines over a period of two years.* Studies by the New York State Department or Labor Exhaustive tests were made by the Division of Industrial Hygiene, of the composition of the exhaust gases given off by a Diesel engine mounted on a test block. These tests showed that certain' quantities of the gases are discharged from the exhaust. On the basis of these figures, preliminary requirements of design and control

Jan 1, 1943

By Gustav Werner, Leonard Greenburg, William B. Harris

Haulage in tunneling operations generally has been done with electric locomotives. As a rule, on short hauls the source of electricity is a storage battery mounted on the locomotive, which, of course, must be removed and recharged periodically. Where the distance from the recharging point to the tunnel face is very long, and where loads are heavy, trolley-driven locomotives are used. Diesel engines have been used in mining and tunneling operations in Europe for a number of years. The recent reports of studies in Belgium1 and by the Bureau of Mines in this country2-4 have indicated the potentialities of this form of power for haulage, mucking, bulldozing and many other underground operations. The hazards attending the use of Diesel engines in more or less closed spaces have long been known. The exhaust constituents that may create a harmful or objectionable environment are carbon monoxide, oxides of nitrogen and sulphur, carbon dioxide, aldehydes and smoke. Lack of precise information regarding the concentration of these gases and the ventilation requirements to reduce them to safe levels has to some extent suppressed their general acceptance in tunneling and mining work. Not until the work of the Bureau of Mines referred to above, and certain experience gained in the construction of the Delaware Aqueduct, ‡ has there been available the requisite information regarding the conditions under which their use may be permitted. This paper concerns itself with the successful operation of Diesel engines underground in the construction of certain parts of the Delaware Aqueduct, and describes the conditions under which Diesel engines have been found to operate with a minimum production of noxious gases. The test data reported were obtained during the operation of Diesel engines over a period of two years.* Studies by the New York State Department or Labor Exhaustive tests were made by the Division of Industrial Hygiene, of the composition of the exhaust gases given off by a Diesel engine mounted on a test block. These tests showed that certain' quantities of the gases are discharged from the exhaust. On the basis of these figures, preliminary requirements of design and control

Jan 1, 1943

By A. J. W. Headlee

RECENT interest in germanium centers around its use as a semi-conductor of electricity in electronic devices. It is generally believed that germanium transistors, diodes, triodes, photocells, and rectifiers will largely replace the present-day vacuum tubes. The germanium electronic devices are much smaller, lighter, and more resistant to shock, and they require only a small fraction of current required for conventional devices. Hence only a small amount of heat is given off by the equipment. This development will require many times the quantity of germanium now being produced, which in 1948 was approximately 1000 lb1 and was obtained almost entirely from zinc ores in Missouri, Kansas, and Oklahoma. No one knows with certainty what the demand will be for germanium by 1956. It may be 40,000 lb.1 Known concentrations in zinc ores are not sufficient to

Jan 10, 1953

By John M. Dale

As much as half of the world's known reserves of elemental sulfur occur at or near the earth's surface in natural or native sulfur deposits of volcanic or sedimentary origin. Yet these reserves constitute only a small percentage of the world's supply. Looked on as marginal materials, they remain relatively untouched despite the current demand and improved prices for sulfur. There are two main reasons for this. The first is the nature and occurrence of the deposits. They are generally small and widely scattered in remote and often arid locations, and the gangue constituents of the ore are apt to vary considerably-not only between deposits but also within deposits. The second reason is the lack of workable and economically feasible processes for recovering sulfur from the ores in such deposits. Historically, the older thermal processes in which the sulfur is vaporized away from the gangue were probably the most successful, but they were inefficient and created pollution problems. A few of the historical processes remain in operation today. Recently, however, an improved thermal process to handle all sulfur-containing surface ores has been designed under sponsorship of the Pan American Sulfur Co. A schematic diagram of this process is shown in Fig. 1. The process equipment consists of a paddle trough conveyor retort which is operated as a closed unit to prevent any air or oxygen from entering the system. Ground surface sulfur ore and heated pebbles are fed to this unit simultaneously. The ore and heated pebbles are slowly conveyed and continuously mixed down the conveyor retort. Heat from the pebbles and heat supplied to the outside walls of the trough conveyor retort raise the ore temperature above the boiling point of sulfur. Sulfur vapors and steam originating from moisture in the ore are ducted to a condenser, and the sulfur is recovered as a liquid. The gangue and the pebbles are discharged from the trough conveyor and separated-the gangue being discarded, and the pebbles being conveyed to a direct-fired rotary pebble heater where they are reheated before they are again charged into the rotary trough conveyor retort. The hot gases which pass countercurrent to the pebbles are ducted to the outside of the rotary trough conveyor where they pass countercurrent to the flow of the ore in order to maximize heat recovery and utilization.

Jan 4, 1969

By J. E. Johnson

OF the many items of information necessary to the successful management of the blast-furnace, few are more important than knowledge of the location and movement of the stock-line: whether the furnace is full and has. been kept so; whether the stock is settling regularly or slipping; and, if slipping, how often it has slipped, at what times, and how far at each time. To obtain these data, a man is sometimes stationed at the top of a. pair of mechanically-filled furnaces, simply to watch and gauge them by hand in the old-fashioned way. - A more recent practice is the suspension of test-rods from ropes leading over pulleys to the ground-level, where the ropes are wound on small drums with graduated peripheries and provided with crank-handles, whereby the skip-man or some other person can quickly and conveniently gauge the position of the stock-line in the furnace. I believe the credit for this great improvement belongs to Messrs. McClure & Phillips of Sharon, Pa., who were, as far as I know, the first to apply it, and who have a patent for it. The valuable indications gained by application of the Uehling pyrometer to the down-comer are Dot to be ignored; but the information thus furnished is somewhat indi¬rect, and there is no scale for the translation of "top-tempera¬tures " into " feet down." Moreover, this apparatus as a whole is delicate, and the cost of its installation and maintenance is high. If the record furnished by the Uehling pyrometer is not in the most desirable form, the test-rods, on the other hand, give no record at all, except through the memory, or notes of a man who, to say the least, is not gauging continuously, and who may omit to report an improperly low stock-line, if it be due to a fault of his own.

Mar 1, 1905

By G. T. Lineberry

Power requirements for a piece of mobile mining equipment are largely dependent on the set of conditions in which they must operate. These conditions are isolated and key parameters are identified. The effect of operating conditions on power determination is investigated. A simulation technique is developed to predict ranges of power demands for off-highway haul units as an archetype, permitting the analysis of changeable operating conditions. This program uses given data, conditions, and probabilities and ranges to solve for individual components of power, which can then be summed. By adopting such a technique, a systematic and rational determination of power is made possible. The usefulness of this basic approach in the determination of power requirements for other mobile mining equipment is emphasized.

Jan 1, 1983

By G. L. Hundley, R. E. Mussler, D. H. Yee, F. E. Block, R. S. Olsen

An anhydrous chlorination process for the recovery of copper from chalcopyrite was investigated. Pelletized concentrate was reacted continuously with gaseous chlorine in a vertical shaft reactor at 550° and 650°C. While the copper was withdrawn with the rest of the metals as molten chlorides from the bottom, 99-x% sulfur was distilled from the top of the reactor. The molten metal chlorides were pulverized and dropped continuously into an upward flowing stream of oxygen. Over 80% of the iron chlorides were converted to oxides in a vertical free-fall reactor at 800° and 900°C while the copper chlorides passed through unoxidized. Copper was recovered in powder form by electrowinning continuously from chloride solutions using a diaphragm cell. The product sloughed easily from a titanium cathode and showed no iron contamination. Current efficiencies and power consumptions averaged 77% and 1.24 kw-hr per lb.

Jan 1, 1974

By I. A. Ettlinger

THE formation that the writer has chosen to call "The Central Arizona Batholith" is included in the Globe, Miami, Ray, Pioneer, Troy, and Silver King mining districts. Its extension to the southeast is in the Banner mining field. Basing his argument on what is known of batholithic intrusions, the author offers reasons for considering all these granitic outcrops as parts of a single great mass of plutonic rock. The United States Geological Survey has subdivided this area into three -quadrangles-the Globe, the Ray, and the Florence. Of the first two, geologic atlases1 have been published, but of the last, the topographic map alone is available. These mining districts include such prominent present-day producers as Inspiration, Miami, Old Dominion, Arizona Commercial, Iron Cap, Superior and Boston, Magma, Belmont, and Ray Consolidated. Among those well known in the past are Silver King mine and Gibson mine. Fig. 1 is a geologic map of the Central Arizona Batholith region. F. L. Ransome's excellent work on The Copper Deposits of Ray and Miami, Arizona,' is of great value to all workers in those districts. His geologic map for the Ray and Globe quadrangles has been incorporated in Fig. 1, and the stratigraphic names employed are those first applied and defined by him in his pioneer work in this region. The purpose of this paper is to show that the ores are related to post-Carboniferous granitic intrusions; that while there does not seem to be any adequate explanation for the distribution of all the igneous stocks, a preexisting structure does appear responsible for at least the location of the largest igneous stock of the region; that the principal producing vein mines are located in the sedimentary rocks in the roof of this batholith, while the disseminated copper deposits are found bordering the lower portions of the batholith exposed by erosion; that primary zoning is illustrated not only on a broad (district) scale but also on a small (individual

Jan 1, 1928

FROM north to south activity is picking up through- out the Labrador Trough-already shown to be one of the world's great iron ore provinces. Center of current activity and interest lies in the mid-southern part of the trough as drills, equipment, and . . . money start to pour into the area near Mt. Wright and Wabush Lake. First major announcement in the area came early this spring when J&L and CCI outlined an estimated billion-ton deposit for "future" operations. Later impetus came from rumored railway for US Steel's Quebec Cartier projects in the Mt. Reed area slightly to the south. As this issue went to press US Steel's request for bids on railway and hydroelectric construction, plus IOCC's decision to step up the time- table on its program in the Wabush Lake area east of Mt. Wright, triggered a flurry of other announcements involving many of the top U. S. and Canadian iron ore firms. Do not look for most of these place names in the average atlas . . . they aren't there yet, but they soon will be.

Jan 6, 1958

By J. E. Tobey, David R. Mitchell, J. H. Kerrick

DETAILED knowledge of purchase specifications established by coal consumers is essential to the successful design and operation of a coal preparation plant. ANTHRACITE Specifications should be considered by both the consumer and the producer as guide posts outlining a certain path for both to follow. Plants differ, therefore specifications must differ to meet the varied requirements. Specifications are not of themselves a "cureall" or an assurance of complete satisfaction in fuel utilization. Specifications should not be regarded as a license to engage in an orgy of buying any and all coals that may happen to fall within their limits. This would lead to the indiscriminate mixing of coals which may vary in their burning characteristics. Different coals of equal grade tend to be individualistic in their burning characteristics. Rather, specifications should be used to help simplify coal selection, to reduce the actual number of coals used over a given period; in other words, to have a stabilizing influence on coal or customer turnover. In the final analysis, the use of too many coals per year in a plant is costly to both the consumer and the producer. Too many sources usually result in higher operating and maintenance costs for the consumer and higher sales costs for the producer. Finally, the statement included in the report accompanying the comprehensive Coal Selection Charts prepared by the Coal Committee of the National Association of Purchasing Agents, and released in 1938, is significant. This Committee worked diligently for a period of 15 years seeking to find a scientific and reliable method for selecting coals. The two following paragraphs are quoted from its report: More important is the fact that no ready-made classification or set of specifications can possibly replace the judgment and resourcefulness of an experienced combustion engineer or fuel technologist, nor the usual need for full scale plant tests under the exact conditions of use before a final decision is made.

Jan 1, 1950

By Max Mason

IN 1923 a Western mining company was experimenting with the device of an inventor designed to locate buried ores by radio. Because the progress was slow and the results were confusing, the company began to doubt the usefulness of the method and invited me to review the whole question of the application of physics to ore detection. I was fortunate in securing the cooperation of several physicists who had worked with me during the war on the problem of submarine detection. This group has been increased and has been studying the problem of physical exploration for ores since that time. It was evident that the problem is a big one, with many angles of approach. Its general features may be set down, in rough outline, as follows: The soils, rocks and ores hidden beneath the surface differ one from another in many respects. These differences may be made to furnish a clew for the physicists working from the surface. To bring these differences into action the physicist creates some kind of an effect which penetrates into the ground and is distorted and reflected when it meets boundaries between different sorts of underground structure. In other words, he sends a message down, and the rocks and ore send back signals in reply. In picturing this process, we should not regard the ground as dense and impenetrable. The kind of messages used pass through the earth about as readily as a sound wave travels the air. If, then, the fundamental procedure is to shout down questions in the hope that an orebody will hear and answer back to us, it is clear that a large part of the expert's study must relate to the kind of questions best suited to the temperament and intelligence of orebodies. It will be easier for the ore to reply to some of our questions than to others, and it is for us to find the right questions. In certain cases, we are spared the necessity of using a messenger; because nature has already provided one. For example, we already have a terrestrial magnetic field which auto-matically and continually conveys messages from underneath. We also have available the earth's gravitational field. which furnishes us

Jan 1, 1927

By H. C. Fowler

No exact demarcation can be made between producfion engineering and engineering research projects which interest production engineers because the results of today's engineering research make possible many of the applied production engineering methods of tomorrow. A corollary of the development of fundamental research is that so-called practical research becomes necessary. Assuming engineering research to include all subjects related to oil and gas production on which knowledge is being increased through experimentation and through analyses of data obtained from both the laboratory and the field, a review of the work of 1932 shows that the fundamental concepts of at least three major problems have become better understood—bottom-hole pressures, solubility of gas in oil, and fluid movement—and that the established data on the relationships of oil and gas have been applied to obtain more efficient and more economic production of both. Engineers no longer are concerned primarily with the initial development of devices for obtaining the pressures at the bottom of wells. Advancement in the technique of obtaining reliable pressure readings in wells has been rapid. One of the first public suggestions regarding apparatus for obtaining precise information at the bottom of oil wells was made before the Petroleum Division of the A.I.M.E. in 1928. Even during the early development stages in East Texas, reservoir pressures were estimated from well-head observations. Soon, however, a number of proved devices and methods were available, and today bottom-hole pressures in many fields are being recorded and studied as an essential part of the production programs. The research now turns to interpretations of data, obtained with these devices, in terms of reservoir energy and to the development of methods whereby the oil and gas will be withdrawn in accordance with rational and equitable programs based on oil-gas-energy relationships. The term ((bottom-hole pressures" should not be interpreted as indicating the full scope of all research on this problem. By using pressure (and temperature) data obtained in related vertical-flow studies,

Jan 1, 1933

By Walter English

THE four papers making up this symposum have been prepared espe-cially for those who have no knowledge of seismograph prospecting. To many people mathematics is a formidable subject, and many are discouraged from studying seismograph prospecting under the mistaken assumption that the mathematical requirements are severe. In the papers presented here there is not a single mathematical equation. We believe that considerable competence in dealing with some of the most important problems of this work can be attained without any mathe-matical training whatever. At the present time, there is a real need for interpretation of results by persons thoroughly competent to bring geologic experience and imagination to bear on data that are subject to multiple interpretation from a strictly physical viewpoint. Likewise, those charged with the responsibility of planning seismo-graph exploration campaigns would do well to become familiar with as much as possible of the technical aspects of the work. They would then be in better position to judge of its success in individual cases. It has often been said that the seismograph is a new structure-finding tool for the geologists to use. Using a tool and using its product are two different things. One does not use an automatic screw-threading machine when he buys a box of screws at the hardware store. Neither does the geologist

Jan 1, 1939

By T. L. Joseph

Blast furnaces are most efficient thermally when the CO2 in the top gas is highest. Oxygen introduced in the air blast is converted to CO in the combustion zones. The extent to which CO, generated in front of the tuyeres, is converted later to CO2 depends upon the ratio of ore to coke in the charge and the degree to which CO2, formed by reduction of iron oxides with CO, reverts to CO by the secondary reaction C + CO2 = 2CO. About 300 to 400 lb. of carbon' per ton of pig iron is normally involved in the solution-loss reaction or direct reduction of FeO with carbon, which produces the same over-all results; that is, lower CO2 in the top gas. Rich2 has recently reported a reduction in fuel consumption at slower rates of blowing on two furnaces in spite of higher heat losses per ton of iron. Lower fuel consumption at slow operating rates was due to more complete reduction of the ore that resulted in higher CO2 in the top gas and consequently more efficient use of carbon. Kinney3 has reported substantial savings in fuel as a result of crushing and sizing the ore charge. Improvements in practice brought about by sintering magnetite concentrates, flue dust and fine ores have been due to the establishment of conditions favoring more complete reduction of the ore in the upper part of the furnace. The extent to which oxides and fluctuations in composition in pig iron affect the quality of steel and finished product needs further study. There is evidence that more thorough preheating and reduction of the ore in the upper part of the furnace tend to give a better quality of iron. Bogatzkii4 found from laboratory work that the amount of oxygen entering electrolytic iron, melted under various slags, was directly proportional to the concentration of free FeO in the slag and inversely proportional to the basicity of the slag. Herty and Gaines5 concluded that the silicate content of open-hearth steel before deoxidation is related to the concentration of silica in the pig-iron charge, indicating that most of the persistent inclusions are silica from the iron. They also found that

Jan 1, 1936

By T. L. Joseph

Blast furnaces are most efficient thermally when the CO2 in the top gas is highest. Oxygen introduced in the air blast is converted to CO in the combustion zones. The extent to which CO, generated in front of the tuyeres, is converted later to CO2 depends upon the ratio of ore to coke in the charge and the degree to which CO2, formed by reduction of iron oxides with CO, reverts to CO by the secondary reaction C + CO2 = 2CO. About 300 to 400 lb. of carbon' per ton of pig iron is normally involved in the solution-loss reaction or direct reduction of FeO with carbon, which produces the same over-all results; that is, lower CO2 in the top gas. Rich2 has recently reported a reduction in fuel consumption at slower rates of blowing on two furnaces in spite of higher heat losses per ton of iron. Lower fuel consumption at slow operating rates was due to more complete reduction of the ore that resulted in higher CO2 in the top gas and consequently more efficient use of carbon. Kinney3 has reported substantial savings in fuel as a result of crushing and sizing the ore charge. Improvements in practice brought about by sintering magnetite concentrates, flue dust and fine ores have been due to the establishment of conditions favoring more complete reduction of the ore in the upper part of the furnace. The extent to which oxides and fluctuations in composition in pig iron affect the quality of steel and finished product needs further study. There is evidence that more thorough preheating and reduction of the ore in the upper part of the furnace tend to give a better quality of iron. Bogatzkii4 found from laboratory work that the amount of oxygen entering electrolytic iron, melted under various slags, was directly proportional to the concentration of free FeO in the slag and inversely proportional to the basicity of the slag. Herty and Gaines5 concluded that the silicate content of open-hearth steel before deoxidation is related to the concentration of silica in the pig-iron charge, indicating that most of the persistent inclusions are silica from the iron. They also found that

Jan 1, 1936

By Ripu Daman Lama

The size of coal pillars in mines until recently has been determined by experience without being based upon scientific investigations. As a consequence, the size of pillars had invariably been larger than could be accounted for because of the number of unknown factors involved which influence the strength, dictating the use of large safety factors. With the mining going deeper, the size of the pillars greatly increases and sometimes a considerable portion of the mineral property are blocked in the mine pillars required to support the superincumbent strata. With the advances in the field of Rock Mechanics, attention of mine planning engineers has been focused upon the design of mine pillars for safe and efficient working as well as decrease losses of coal. The problem involves the study of three factors: (1) Presence of stresses in the area and their distribution on pillars in the course of extraction. (2) The influence of external factors on the strength of coal. (3) The inherent mechanical properties of coal. These aspects have been studied by a large number of investigators, the first by in-situ stress measurements and photoelastic studies and the second and third aspect by studies conducted in the laboratory on small size specimens (Bunting, 1911; Evens & Pomeroy, 1961; Gaddy, 1956; Greenland et al, 1941; Steart 1954). The size of the specimens tested in the laboratory has been limited to a few inches and the results obtained have been extrapolated by large factors, sometimes several hundred times the largest specimen tested. In these tests much consideration has not been given to

Jan 1, 1971