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By D. Harrington

ANNUAL or necessary inspections and investigations of coal mines for various purposes were made possible through the Federal Coal Mine Inspection Act of May 7, 1941, which authorized entry to the Secretary of the Interior through the Bureau of Mines. Primary object of these inspections is to obtain information pertaining to health and safety conditions. Among the purposes for which the data are to be used, are annual reports to Congress, the publication of inspection reports, and the compilation and publication of statistics. The act states that inspections and investigations shall be made by employees of the Bureau of Mines, who shall co-operate with other bureaus of the U. S. Department of the Interior, as well as with the official mine-inspection, safety cr health agencies of the several states and territories. The act specifies that a coal-mine inspector shall have "the basic qualifica-

Jan 1, 1946

By Benjamin Gi ldersleeve

Uniquely colored, thin-bedded quartzite is quarried between Crossville and Crab Orchard in Cumberland County, Tenn. It is produced in all sizes up to the limits of transportation from beds usually ranging in thickness from less than 1/2 in. to 6 in. The stone is very resistant to wear and weathering and is marketed throughout the country for many different purposes in exterior and interior construction. The annual production exceeds 36,000 tons, valued at nearly $1,000,000.

Jan 1, 1950

By Finney, W. R.

MUCH has been said and written of the "Big Inch," of the terrific obstacles encountered in its construction, of the colorful and tough men engaged in its building, but little has been publicized of the engineering and economic problems behind the scenes. Long before Pearl Harbor it was apparent to the petroleum industry that a critical oil shortage could be expected along the Atlantic seaboard, owing to delay in tanker deliveries as a result of convoy movements, and to allocation of vessels for foreign shipments. This area, with a normal consumption of approximately 1,800,000 barrels per day of oil and products, was almost entirely supplied by tanker. Pipe lines supplied an average of only 20,000 barrels per day in 1939, 40,300 barrels per day in 1940, and 55,000 barrels per day in 1941. A small amount of oil and products was also delivered via barge.

Jan 1, 1943

By John F. Wiggert

DURING the early years of Homestake operations, shaft signaling from the cage tenders to the hoisting engineers was done by mechanical means. Small steel cables or jointed steel rods were suspended in the shaft compartments and counterbalanced with weights or springs. These cables or rod strings were connected to the mechanically operated gongs at the engineers' stations by means of bell cranks and steel wires. The system was simple and economical and served the purpose well until the mine reached a depth of 1000 ft., then the system became slow and cumbersome and required a considerable amount of muscular effort to operate it with much speed, because of the inertia of the heavy moving parts. The mechanical signaling was superseded by a simple electrical system consisting of a single pair of wires in steel conduit for each shaft compartment. In the shaft at each station a pull switch was connected to the wires. The switches were operated by means of bell cords, which extended from station to station. This electrical system was a great improvement over the mechanical one, but it had one serious drawback, which also applied to the older system; namely, the engineer did not know where a signal originated. Later on this signaling was improved to overcome this drawback, and to give the engineer a positive indication of a signal's origin. In this system a separate return wire from each pull switch is carried to an annunciator at the engineer's station, where it indicates the signal's origin. While the annunciator system used by Homestake is very safe and reliable, it has the inherent drawback of all wire-connected systems in that it is impossible to send a signal from a moving cage. A number of years ago Homestake became interested in the possibility of using some sort of radio transmission for shaft signaling. The company did much experimental work with purely radio signal transmission, but no practical way was discovered to use radio transmission in a mine shaft for signaling to or from a cage. Therefore, all efforts were directed to devising a practical way of using the hoisting rope as part of the circuit. It was realized that the return circuit from the rope would need to be through electrostatic coupling between the cage and the earth or ground sides of the shaft, because the guides would not always be wet enough to make possible good electrical contact between the cage and earth, therefore relatively high-frequency alternating current was chosen as the medium of transmission. Soon a practical system was developed for transmitting an electric current from a moving cage over an electric circuit of which the hoisting rope was a part. A high-frequency electric current is used as a carrier to transmit the signals or mes-

Jan 1, 1941

By F. O. Garrabrant

Power is furnished to the Climax Molybdenum Co. by the Public Service Co. of Colorado over two 100,000-volt lines to a bank of three 3333-kva. transformers 100/13.8 kv. These transformers are so designed that with the addition of forced cooling their capacity may be increased 331/3 Per cent at 12,000-ft. altitude. Under present conditions, these transformers are operated at 140 per cent of their rating with forced air cooling. On the secondary side of this bank there is a 15-kv., 1200-amp. Westinghouse oil circuit breaker provided with automatic reclosing relays allowing three successive short circuits before lockout. From this breaker 13.8-kv. power is transmitted to a central switching station (Fig. I) where all circuits radiate to the different operations of the property. Each circuit is protected by a 23-kv., 600-amp. oil circuit breaker with by-pass and isolating disconnecting switches.

Jan 1, 1947

By AIME AIME

HE State of Utah has an area of 84,990 sq. mi., and like other inland states in the West its population, although steadily increasing, is relatively small. The fact that it is a state possessing vast mineral resources is attested by a careful study of statistics which have been compiled by Federal and State investigators. Some idea of the extent of these resources and the degree of development of a particular state or region may be gained by such a study, but in the case of Utah statistics and other available information fail to portray completely the true extent and value of its existing metallic and non-metallic resources. The State is probably more widely known for its production of metallic ores which has placed it in an eminent position among the metal mining states of the Nation.

Jan 1, 1925

By OTTO HERRES

TO operate the bituminous coal industry in the United States in 1929 cost $770,237,000, of which $30,739,000 was paid for purchased power and $34,947,000 for new machinery and equipment. Equipment aggregated 3,124,000 hp. A mining industry that spends $65,000,000 a year for power and machinery is likely to be fairly well mechanized, and when the machinery in use takes three million horsepower to drive it, the probabilities are that mechanization has been in progress in at least some of the mines for quite a few years. Mechanization in its broadest sense implies machine cutting, power drilling, mechanical loading, electric haulage, mechanical sizing and cleaning, and lesser applications of machinery to mining operations. But the introduction and development of mechanical loading has been the feature of coal mining recently and its extraordinary progress is causing great changes within the industry. First, let us look at the records. The quantity of coal loaded mechanically in bituminous mines was:

Jan 1, 1933

By HORACE H. EJIRICH

(New York Meeting, February, 1912.) PREFATORY NOTE.-The first part of this paper was sent to me by Mr. Emrich nearly nine months ago ; and. I held it, waiting for the second part, which he had promised to forward soon, so that I might submit the whole to some of his former professional associates, and advise him of their criticisms and suggestions before offering his work to the Institute. But, five days before the second part reached me, I received by telegraph the news of Mr. Emrich's sudden death. The paper has therefore not had the benefit of such a revision by the author as might have made it in some respects clearer and more complete. Nevertheless, I believe that experts in the branch of metallurgy with which it deals will find it both original and suggestive.-A. EILERS. I. PARTIAL REFINING IN THE ANODE-FURNACE. During my connection with one of the large New Jersey copper-refineries, and probably before that period, from 15 to 20 per cent. of the copper-bullion received was the very foul, leady blister-copper produced from lead blast-furnace matte. It had been customary to mix a small part of this blister with each charge of purer pig-copper, in the effort to dilute it as much as possible before casting into anodes; but tank-house conditions were such that I was led to try making entire furnace-charges of this blister, and refining it as much as possible in the furnace-afterwards casting to anodes and refining electrolytically, in tanks and solution separate from the main bulk of the purer copper. In making this experiment, notes were made, for several furnace-charges, of everything thought to have a bearing on the question, and some interesting facts were brought out, both in the furnace-working and afterwards in the tanks.

Jun 1, 1912

By C. T. Liu, J. Gurland

The deformation behavior in tension of spheroidized carbon steels was studied at room temperature as a function of carbon content, 0.065 to 1.46 wt Pct, and carbide particle size, 0.88 to 2.77 p. It was found that the Hall-Petch strength-grain size relation is directly applicable to the yield and flow stresses of the two lower-carbon steels , 0.065 and 0.30 pct C. The strength data for the medium- and high-carbon steels, 0.55 to 1.46 pct C, also satisfied the Hall-Petch relation, provided that these data are based upon the particle spacing. Beyond 4 pct strain, the flow stress data of all the steels studied could be represented by the same Hall-Petch relation with dinerent spacings for grain boundary and particle strengthening. The behavior of the higher-carbon steels was consistent with the postulated formation of a dislocation cell network during processing and initial deformation (up to 4 pct strain). The cell size was assumed to be equal to the planar particle spacing. The true stress at the ultimate tensile strength was also found to be a function of the particle spacing. At a given temperature and strain rate, the yield and flow stresses of carbon steels depend on the type and dimensions of the microstructure. Starting with the work of Gensamer et al. in 1942,' experimental studies on pearlitic and spheroidized carbon steels revealed that the strength of steels is a function of two main parameters: the ferrite grain size2'3 and the carbide particle spacing;1'4'5 on this basis, two different strengthening mechanisms have been developed to apply to steels of low and high carbon contents, respectively. In polycrystalline iron and mild steels the grain boundaries are regarded as the major structural barriers to slip. The relation between strength and grain size is generally represented by the Hall-Petch equation which is based on a linear proportionality between strength and the inverse square root of the average grain size.2'3y677 However, Gensamer et al.' and Roberts et related the yield strength of medium -and high-carbon steels to the carbide particle spacing alone, and they found a linear relation between the logarithm of the mean free path in the ferrite and the yield strength in both spheroidized and pearlitic steels. By means of the electron microscope, Turkalo and LOW' extended the study to finer structures; they concluded that the logarithmic relation is not valid for the entire range of microstructures unless grain boundaries are also included in the measurement of the mean free path. For the specific case of spheroidized steels, Ansell and aenel' found that the yield strength data,4'5 when plotted as a function of mean free path, fit the Hall-Petch equation; however, T'ysong found that the same data fit the 0rowanl0 relation if a planar inter-particle spacing is used. Recently Kossowsky and ~rown" studied the strength of prestrained spheroidized steels, 0.48 and 0.95 pct C, and concluded that the strength due to the carbide dispersions varies linearly with the reciprocal of the square root of the mean free path between carbide particles and dislocation networks. Such networks were first observed by Turkalo." The conclusion common to all these studies is that the available slip distance in the ferrite is the most important variable in determining strendh. Previous work on carbon steels is restricted to limited composition and strain ranges. The mechanism which governs the flow properties is not clearly understood, and, in particular, little is known about the composition dependence of the transition between grain boundary strengthening and particle hardening. The purpose of the present work is to investigate the strengthening mechanism in spheroidized steels over a wide range of carbon content, 0.065 to 1.46 wt pct, and plastic strain, yielding to necking. The spheroidized structure was chosen because of its relative simplicity and the relative ease of control and measurement of the structural parameters. The experimental work is limited to tensile testing at room temperature at constant extension rate. The effects of the carbide particles on the fracture behavior of spheroidized steels are discussed elsewhere.13 EXPERIMENTAL PROCEDURE Eight different grades of vacuum-cast carbon steels were supplied in the form of forged and rolled plate by the Applied Research Laboratory of the U.S. Steel Corp. The compositions furnished with these steels are given in Table I; the carbon content ranges from 0.065 to 1.46 wt pct, or from 1.0 to 22.3 vol pct of carbide. The steel plates were cut transversely into rods a little larger than the test specimens, 1 in. gage length, i in. diam. The rods were austenitized in air (enriched with CO by a consumable carbon-rich muffle) at 50° C above theA, orA., temperature for 2 hr and then quenched in oil with vigorous stirring. The as-quenched rods were tempered in two stages in order to obtain the desired distributions and sizes of carbide particles. The rods were first tempered at 460° C for 10 hr and then at 700" C for periods ranging from 4 hr to 3 days, in vacuum. After final machining, all specimens were vacuum-annealed again at 650°C for 1 hr in order to relieve residual stresses. The tension tests were carried out in two steps. The initial part of the load-strain curve, up to about 2 pct strain, was determined on a Riehle testing machine with an extensometer of small strain range, 4 pct strain, in order to obtain the yield and initial flow piopertiesi As soon as the first part of the test was finished, the specimen was placed in an Instron testing machine equipped with a strain gage extensometer with a maximum strain range of 50 pct. The load-strain curve to fracture was

Jan 1, 1969

By AIME AIME

NEW YORKERS look forward to the third week of February as the time of the year when they can count on seeing their friends-from far and near gathered in the city for the four-day annual session of the Institute.., Indeed, the metropolitan district is so large that in engineer who lives in New, Jersey and has his office on the lower end of Manhattan island may easily pass a whole year without seeing an acquaintance who lives in Westchester and has an office near Forty-second Street. If the Institute served no other function than to provide a place where friendship may be renewed, ideas exchanged, and new acquaintances made it would still be worth while. But when about 30 technical sessions at which about 160 papers are read and discussed are compressed into four days the annual meeting is also entitled to high rank as an intensive course of post-graduate instruction in the newest development in mining and metallurgical technology. Last, but not least, it is the occasion of a good time for one and all, even if they do get more than a little behind on sleep before the end of the fourth day. Nine o'clock is the time set on Monday morning for the beginning of registration, but a half-hour before that a number have always 'put in an appearance, and this is fortunate, because by 10 o'clock four sessions had begun, those on mining methods, geophysics, a round table on the valuation of coal, and the session of the Local Section delegates. Three committees of the A. S. T. M. were also in simultaneous session, so the meeting may be fairly said to have started "in high."

Jan 1, 1931

By A. T. Yu

As the first loads of Noamundi iron ore rumbled into the new 54-in. Gyratory Crusher on March 30, 1968, one of India's largest and most modern iron ore processing complexes began operations. The completion of the $13 million mining and processing complex brought to a successful conclusion the second chapter of a phased expansion program initiated in 1958 by India's gigantic Tata Iron and Steel Co. The completed complex will yield annually 2.5 million tons of washed, sized ore and sinter fines destined for Tata's furnaces at Jamshedpur. Hewitt-Robins Div. of Litton Industries was awarded the turnkey project on the basis of world- wide competitive bids. Eighty miles southwest of the city of Jamshedpur, Noamundi lies on an approximate geographic grid of 22º-5' latitude north and 85º-30' longitude east. The mine is approximately 600 ft above sea level.

Jan 11, 1968

By George A. Miller

THE outstanding characteristic of the American business man is that he likes to run his own business his own way, without any interference from his wife, his friends, his bankers, and least of all from his government. The oil man, like the miner, is an American business man in which this special characteristic is even more pronounced. It may be because he has been an explorer and is more nearly like those pioneering Americans who explored, developed, and built these United States.

Jan 1, 1944

Jan 1, 1879

By H. A. Kuhn

THE Pittsburg coal field in western Pennsylvania, is conceded to be the most important in the world. To measure its importance it is necessary to understand the extent of its service in the various industries of the country. Probably 90 per cent. of the pig iron manufactured in the United States up to the present time has been made by using coke manufactured from the Pittsburg coal seam in western Pennsylvania. This coal field is the foundation on which the city of Pittsburg rests and is the reason for the great growth of the iron industry in the Pittsburg district. Iron ore is brought to this district, not because Pittsburgh is a. natural location, over other locations, for the iron and steel industry-as its position places the manufacturer at the mercy of the railroads-but the ore is brought 1,100 miles to meet the fuel. It can be said that the illuminating-gas industry in the United States has used this coal exclusively to the same extent that the pig-iron maker has used it. It may be also said that 20 to 25 per cent. of the fuel used on railroads in the United States conies from this coal field. The Pittsburg coal field is unquestionably the center of the industrial population of the United States, for in addition to the industries of the district and those closely adjoining, it has tributary to it all the cities and industries along the Great Lakes and practically all of Canada with the exception of the extreme western and eastern ends. It supplies the industries and population west of Duluth and Superior many hundreds of miles. This coal is floated down the Ohio and Mississippi rivers, supplying the towns en route, and is delivered in New Orleans, a distance of 2,200 miles, for approximately SO to 90 c. per ton transportation cost. It is delivered on the docks of Superior and Duluth at a cost of transportation 50 c. a ton less than the cost of transporting the same coal from Pittsburg to a local consumer in Philadelphia. With other Appalachian coals it has large markets east and along the seaboard, especially for byproduct-coke making and the illuminating-gas industry. It is considered the premier railroad fuel of the world on account of the fact that this coal in a given-sized locomotive will probably haul more cars than any other coal in the

Jan 10, 1914

By JOHN LANE DYNAN

HE Tonopah Extension property consisted originally of three claims, with an area of 38 acres. In 1902 a shaft, now known as No. 1, was started near the eastern end of the property, close to the Tonopah Mining Co.'s boundary line, in the. andesite cap rock' which covers the ore-bearing formations in the western end of the Tonopah district. A short distance below the 60-ft. level, the orebodies pinched out, although the veins continued. This shaft has not been used since 1916. Before 1910, the production was small, coming mostly from small shoots of high-grade shipping ore. In that : year, the, company started its 30-stamp mill and cyanide plant; the mill was later enlarged to 50 stamps, with a corresponding increase in the cyanide-plant capacity, which brought the capacity of the mill up to 350 .tons per day. The total production of the mine to Oct. 1, 1920, is 871,177 tons of ore, from which was recovered 15,267,216 oz. of silver and 156,241 oz. of gold.' This makes an average recovery per ton of 17.5 oz. silver and 0.179 oz. gold. The average price received for silver since' the beginning of operations is 65.87 c. per oz., and the average value recovered from the ore-'is $15.25. The area of the property has been gradually increased by purchases and consolidations of adjoining ground until it is now 647 acres. A new shaft, known as No. 2, was started in 1912, 1600 ft. west .of No. 1, and in the following year a crosscut on the 750-ft. level of this shaft resulted in the discovery of the. Murray Vein system, from which the greatest prosperity of the mine has come. This vein, with its related veins,

Jan 1, 1921

By W. R. Wilcox

The camphor-anthracene system was chosen as a transparent low-melting analog of the zirconium carbide -graphite system. Camphor and zirconium car -bide both grow nonfaceted, while casting of mixtures yields platelets of both anthracene and graphite. Zone melting of thin layers of organic was observed under the microscope. Irregular lamellar structures were produced at high values of the ratio of the temperature gradient G to the zoning rate V. The anthracene invariably led the camphor, indicating lower kinetic undercooling for the anthracene. The lamellar spacing was an order of magnitude greater than typical spacings for metal eutectic systems. Exact behavior depended on orientation of the anthracene. Oriented dendritic structures were produced at low values of G/V. Transient and oscillatory behavior were also observed—much of it unexpected. A.RC-CAST refractory carbide-graphite mixtures are promising thermal-shock resistant materials. Oriented structures of these materials would be superior to arc-cast materials for many applications. Mollard and Flemings1 and Cline2 have shown that aligned structures can be obtained for a wide range of Pb-Sn alloys. However, these metals both solidify in a nonfaceted manner while graphite yields platelets or flakes. In addition only small diameter samples of Pb-Sn alloys were produced because it was necessary to avoid free convection and to have high temperature gradients. The purpose of the present work was twofold: 1) To observe the solidification of a transparent low-melting analog of carbide-graphite systems and 2) to see if larger diameter samples can be produced. EXPERIMENTAL PROCEDURE When zirconium carbide-graphite mixtures are cast, the resulting structure naturally depends on composition. Carbide-rich mixtures yield metal-like nonfaceted carbide dendrites in a eutectic matrix. Graphite-rich alloys have graphite platelets in a eutectic matrix. Empirically it was found that camphor-anthracene mixtures produce similar structures with camphor being nonfaceted and anthracene forming plates. The organic eutectic melted at 116°C and was composed of 78 wt pet camphor.3 The camphor used was U.S.P. grade from Fisher Scientific Company; the anthracene was 98+ pet fro Aldrich Chemical Co. The impurity content is judged to be on the order of 1 pet. Mixtures ranging from 50 to 88 wt pet camphor were employed for the experiments. All but one of the experiments were performed on the microscope-stage zone melting apparatus described in detail elsewhere.4 The organic mixtures were contained in horizontal cells made of microscope slides or cover glasses. In most of the cells the organic was present as a very thin layer, thus giving almost two-dimensional growth behavior. The cells were moved slowly under a heated wire, which caused a molten zone to move through the solid at rates ranging from 0.01 to 5.4 cm per hr. The temperature gradient was estimated before moving the zone by measuring the distance between the line where all solid was melted (freezing point) and that where solid first began to melt (eutectic temperature). The temperature gradient was found to be 465°C per cm in the thinnest cells used, which were made by pressing together two microscope cover slips in the organic melt and then rapidly withdrawing them. RESULTS The experimental results are described in four parts: simultaneous growth, dendritic growth, irregular growth, and transients and erratic phenomena. Steady state data are summarized in Fig. 1. Except where noted all comments are for the cells containing a thin layer of organic. A) Simultaneous Growth. Simultaneous and roughly parallel growth of anthracene and camphor was obtained over the full range of compositions investi-

Jan 1, 1970

By William J. Coulter

WITHIN the United States the problem of meeting maximum production by our metal mines has been solved by: (1) Conservation of man power by mechanization. (2) Increasing man-power efficiency as expressed in tons per man-shift by the adoption of new and more efficient methods. (3) Production from submarginal properties made possible by some form of government subsidy. (4) Selective mining of high-grade areas. (5) Drawing on broken ore reserves and reducing advanced development work to a minimum. (6) Making maximum use of available equipment. (7) Repairing equipment that normally would be replaced. (8) Working a seven-day week on a three-shift basis to get maximum use of equipment and man power. (9) Adoption of incentive plans to increase maximum efficiency and unit production. (10) Important advancement in metallurgy, resulting in larger recoveries. (11) Improvements in safety, health, and general working and living condi-

Jan 1, 1945

By CHARLES M. A. STINE

IN fighting a war the all-absorbing intent is to win. There is little time to analyze the rush of events or to appraise their consequences beyond the war's end. The united objective is, rightly, success for our arms. Yet under the pressures of a great war there may be compressed scientific, economic and social developments that might have taken many decades to achieve under less urgent conditions. Their effects on our lives and all civilization may be more wide-reaching and lasting than any military conquest. They constitute one of the must imperative incentives to victory. No American, least of all any scientist worthy the name, conceivably could endorse war as a justifiable means to progress. The destruction of life and property wrought by the present war far exceeds the havocs of a century's earthquakes. Most of mankind is burning itself on an altar of paganism. Nonetheless, one fact is inescapable Despite the recurrent malady of war history's overall course is forward. Mankind has the habit of rising phoenix-like from its own ashes to attain greater heights. Progress is immortal.

Jan 1, 1942

By W. F. Tanner

A river delivers a given load of sand, and hence heavy materials, into the sea. The load is fixed by drainage basin characteristics and processes. Wave energy available for redistributing that load is fixed in an entirely different way. An equilibrium diagram of these two parameters (load vs energy) pennits a tentative prediction of what will happen to the heavy minerals. Alluvial rivers transport a mechanical load which consists essentially of wash load (finer than about 0.05 mm in particle diam), bed load (coarser than about 0.10 mm) and the transition sizes in between. A few rivers carry no appreciable mechanical load, and are excluded from this discussion. An example of the latter is the Suwannee River of Florida, which empties across an oyster bar into the Gulf of Mexico and does not build a delta despite the absence of significant waves or currents in that part of the Gulf. An alluvial river may deliver its load into a protected sediment trap (such as an estuary, sound or lagoon), onto a low-energy coast (where it builds a delta) or onto a high-energy coast (from which spot the river load is swept away). The nature and disposition of the load depends, obviously, on three sets of factors: 1) drainage basin characteristics and processes, which determine quantity and make-up of the load; 2) coastal structure and geomorphology, which determine the kind of river-sea coupling which

Jan 1, 1962

By Sidney Snook

FLUORSPAR production is the most important industry in a compact area in southern Illinois and western Kentucky bordering the Ohio River. Producers' activities do not usually figure much in the mining news of the country, so that few know that the last year or so has been an unusually active one. Mine shipments more than doubled in 1939 compared with the poor year 1938. The average price changed but little, though it is now about one-sixth higher than at the beginning of last year. The outbreak of war in Europe a year ago lent an immediate stimulus to the industry, though only about 15 per cent of the domestic consumption is normally imported, thanks to a tariff of $8.40 per ton, equivalent to about 30 per cent ad valorem. Be- cause of the increased production and many expansions and improvements in the mines and plants, the period since the beginning of 1939 has been the most important one for the industry in the last 15 years.

Jan 1, 1940