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By Harry A. Roe

The power drag scrapers and the slackline cableway excavator have been called "long-range excavators." Broadly, their field of usefulness is restricted to work in which their long range of action permits them to operate economically, and which other, possibly more conventional, excavating units cannot do. Both of these machines dig or lift material and transport it to a remote dumping point. They combine these two functions in a single machine, nearly always in a single straight-line motion. The purpose of this paper is to examine the important features that distinguish the machines in this group from each other, as well as from other groups. The Machines The "power drag scraper" is a long-range excavating machine that employs a bottomless drag scraper operated back and forth between digging and dumping points by two haulage cables. The typical arrangement is that of Fig. 1. This is the "slusher" of the underground mine, as well as the "dragline scraper" of the sand and gravel industry, and other open-pit mining operations.

Jan 1, 1938

By Paul M. Tyler

MUCH information concerning pegmatites which was thought to be true a few years ago has been proved false, and what is now actually known about some pegmatites is not true of many others. The erratic and seemingly unpredictable structure and variable composition of this class of mineral deposits has been widely emphasized. Even parts of the same pegmatite body exhibit marked differences in texture, mineral composition, width, and attitude. Constructive geological thinking in respect to pegmatites now aims to establish general laws rather than to stress the confusing diversity of features having no special economic significance.

Jan 9, 1953

By Harry A. Roe

The power drag scrapers and the slackline cableway excavator have been called "long-range excavators." Broadly, their field of usefulness is restricted to work in which their long range of action permits them to operate economically, and which other, possibly more conventional, excavating units cannot do. Both of these machines dig or lift material and transport it to a remote dumping point. They combine these two functions in a single machine, nearly always in a single straight-line motion. The purpose of this paper is to examine the important features that distinguish the machines in this group from each other, as well as from other groups. The Machines The "power drag scraper" is a long-range excavating machine that employs a bottomless drag scraper operated back and forth between digging and dumping points by two haulage cables. The typical arrangement is that of Fig. 1. This is the "slusher" of the underground mine, as well as the "dragline scraper" of the sand and gravel industry, and other open-pit mining operations.

Jan 1, 1938

By Claudio Gutiérrez

The action of quebracho in the selective flotation of fluorite and calcite has been studied. It has been found that the unavoidable ions produced by dissolution of these minerals can precipitate calcium oleate which profoundly influences the adsorption of oleate. The depressing action of quebracho is due, at least partly, to a decrease of the oleate adsorption. The depression of flourite flotation by quebracho in the presence of calcium is due to the fact that precipitated calcium oleate can become only physisorbed, its adsorption being strongly prevented by quebracho. It is concluded that adsorption experiments with flourite must be conducted with a flotation-size mineral, which has a lower dissolution rate than when finely ground.

Jan 1, 1980

Discussion of the paper of W. R. Shimer and F. O. Kichline, presented at the New York Meeting, October, 1913, and printed in Bulletin No. 81, September, 1913, pp. 2361 to 2377. ALLERTON S. CUSHMAN,* Washington, D. C.:-I have been much interested in Mr. Shimer's valuable contribution. The apparent fact that the oxides of certain metals which are not reduced by hydrogen per se, are reducible when the oxides are dissolved in iron in small quantity, is brought out for the first time, and is worthy of the careful attention of investigators. The Ledebur method has been subjected to considerable criticism, owing to the alleged fact that it did not measure the oxygen combined with impurities. Personally I have found the method extremely helpful in spite of the minute quantities of oxygen with which it deals. Mr. Shinier points out that the highest oxygen he obtained by over-blowing was 0.074 per cent., while the minimum quantity in a properly finished steel was in the neighborhood of 0.02 per cent. The Ledebur method is used as a constant check on the quality of heats made in practice under my direction. In dealing with a very pure commercial iron, we should expect to find and would find difficulty in galvanizing sheets made from a heat running 0.07 per cent. oxygen. In fact, we do not like to have the oxygen rise above 0.03 per cent. I am inclined to agree with the author that excessive oxygen leaves a bath of metal in a very short time, but nevertheless I believe it takes only a very little combined oxygen to begin to make its presence felt in the pickling and galvanizing department, when sheet metal is the product manufactured. As Mr. Shimer points out, the higher the carbon, the lower the oxygen danger, and it is partly for this reason that the manufacture of carbon-free metal in the open-hearth furnace has to be so very carefully watched and controlled from the furnace through to the finished product. It is quite possible that, there is a critical temperature of dissociation between iron and oxygen, although the critical points may vary in baths of different carbon content. Unfortunately, the accurate determination of the temperature of a molten bath at the time of pouring or teeming is a very difficult matter. For a long time I have been wishing that there were some reliable data which would indicate the effect of the tem-

Jan 12, 1913

By Chester O. Ensign

Results of the application of geologic knowledge to grade control have been remarkable. Grade reduction from dilution has been diminished from greater than 9% at the time of the program's beginning to about 2% at present. This has resulted in an increase of about 1.8 lb of copper per ton of ore mined and has made a substantial contribution to earnings at White Pine during the past two years. Even more improvement is expected in the future. The White Pine orebody, situated in the southwestern portion of the Keweenaw peninsula of upper Michigan, is a gently dipping stratiform or bedded deposit. Copper distribution is stratigraphically controlled with higher values being confined to specific beds in the ore column. Room-and-pillar mining is practiced. Mining technique and geologic characteristics present a special array of problems in controlling the grade of ore.

Jan 4, 1964

By Clifford Frondel

THE aluminum oxide known as corundum has several varieties that have been used as gem materials since ancient times. These include the red variety called ruby, the blue variety sapphire, and the asteriated types of ruby and sapphire. Asteriated sapphire was known to the ancients under the name of astrios, and descriptions of this gem were given by Pliny and other early writers. The relation of these gem materials to each other as varieties of a single species, corundum, was first clearly established by Haüy in 1805 and J. M. Güthe1 in 1809. Natural gem corundum is obtained principally in Ceylon, Siam, Burma, India, and Australia. Star sapphires and rubies always have been highly prized and in recent years have become particularly popular in the United States. Natural star rubies of large size and fine quality are extremely rare and rank with large and fine emeralds and diamonds as the most valuable of gem stones. Interest thus attaches to the recent success in commercially synthesizing star sapphires and rubies of a size and perfection unmatched by nature.

Jan 1, 1954

By J. V. Emmons

It has long been known that the outside skin of tool steel frequently exhibits properties widely different from the interior of the mass.

Jan 1, 1915

By Henry Mulryan

The largest and purest known deposit of diatomite is being actively mined and processed 3 1/2 miles south of Lompoc, Santa Barbara County, Calif., by the Johns-Nlanville Products Corporation. The workings cover 4000 acres, the depth of economically recoverable diatomite being 1000 ft. (Fig. 1). Lompoe, a community of 2500 population, is situated in the Santa Ynez River Valley 10 miles inland from the Pacific Ocean. It is 44 miles

Jan 1, 1938

By Henry Mulryan

The largest and purest known deposit of diatomite is being actively mined and processed 3 1/2 miles south of Lompoc, Santa Barbara County, Calif., by the Johns-Nlanville Products Corporation. The workings cover 4000 acres, the depth of economically recoverable diatomite being 1000 ft. (Fig. 1). Lompoe, a community of 2500 population, is situated in the Santa Ynez River Valley 10 miles inland from the Pacific Ocean. It is 44 miles

Jan 1, 1938

By J. Spotts McDowell

INTRODUCTION The magnitude of the thermal expansion of silica brick, and its inability to withstand rapid temperature changes, present problems of considerable importance in the manufacture of siliceous refractories. In the study represented by the experimental data herein described, these problems are considered from the point of view afforded by the results of recent investigators: Fenner and his associates of the "Geophysical Laboratory, Washington, D. C., who have established the stability relations of the silica minerals, and Endell and co-workers in Berlin, who have studied the changes brought about in the constitution of siliceous refractory materials upon the application of heat. In the process of manufacture, the quartzite from which the brick is made changes in part into cristobalite and tridymite. The attempt is herein made to determine by microscopic methods the degree of transformation in various specimens of test bricks manufactured at slightly varying temperatures of burning, with varying coarseness of grain, and to determine the effect of repeated burning. The effect of variations

Jan 10, 1916

By Charles W. Dickson

Jan 1, 1904

By D. Harrington

WHEN the word gas is mentioned in connection with mining, almost invariably it is inferred that the explosive gas, methane, is in mind and that it must refer to coal mining. While it is true that methane occurs, or is likely to occur, in almost any or all coal mines, it is also a fact that the metal mines of the world have in them by far a greater variety of gases than have the coal mines. In many cases the gases in metal mines are as dangerous to individuals as the gases likely to be found in coal mines; in some instances the metal mine gases are even more deadly. The coal mine is more likely to have methane than the metal mine, in rare instances it may have high percentages of nitrogen or high carbon dioxide, or there may be a deficiency of oxygen where the air is confined in a blind end or in a sealed region; much more rarely there are found in coal mines in relatively small percentages, ethane, or other hydrocarbons with odor of ether, gasoline or kerosene, or there may be minute percentages of hydrogen sulfide. In time of coal mine fire or explosion, there is likely to be high carbon monoxide (4 per cent. or over in some cases) and if the coal contains much sulfur, there may be some sulfur dioxide in the fire fumes. In metal mines there are a number of cases of occurrence of methane and attendant explosions; some metal mines have appreciable percentages of the decidedly explosive hydrogen; in some metal-mining regions carbon dioxide flows into the mine, fills the workings and overflows just like water. In other regions, at many working faces there are high-temperature gases containing a mixture of gases of sulfur (sulfur dioxide, hydrogen sulfide and possibly SO3 in some cases) together with carbon dioxide and nitrogen, and the deadly hydrogen sulfide in lethal proportions is found in some high-sulfide metal mines at blasting time. Carbon monoxide constitutes a decidedly dangerous day by day hazard in connection with metal-mine blasting, because of the heavy charges of dynamite that are used and the use of fuse, which in burning gives off much carbon monoxide. The poisonous gas hazard is accentuated because of the relatively small openings where metal-mine blasting is done and to the inefficient ventilation of the usual metal mine.

Jan 1, 1930

By Reynold Q. Shotts

CHEMICAL methods, based on the relative rates of oxidation of fusain, bright coal, and dull coal by nitric acid, have been devised to determine these coal components.1-4 Results obtained by oxidation methods for fusain have been checked against results obtained from microscopic methods5, 6on duplicate samples of the same coals, but to the author's knowledge this has not been done for bright and dull coal components. For this reason it is not certain that the two methods of analysis identify essentially the same chemical or physical units. It would be highly desirable to see results of the application of both methods to duplicate samples, but in the absence of any such data the author has attacked the problem indirectly. From the U. S. Bureau of Mines samples were obtained of three Alabama coals which the USBM had analyzed optically and reported on over the past 30 years. These samples were subjected to analyses by oxidation rate methods. Results of this work, and comparisons with the USBM analyses, have been published." This was the first indirect approach to the problem. The present report attempts a second indirect approach by way of internal validation. By nitric oxidation samples of two whole coals were carefully analyzed for fusain, bright coal, and dull coal. One coal was analyzed in duplicate. Duplicate portions of each of the coals were divided into three density fractions by means of heavy liquids. A duplicate portion of one of the coals was divided by sieving into three size fractions. Each fraction was analyzed by oxidation and its percentage composition calculated in terms of fusain, bright coal, and dull coal. Because the weight percent of each fraction was known, a material balance calculation for the whole coal was also made. The resulting reconstituted analysis of the whole coal could be compared to that determined by direct analysis. In addition, specific reaction rate constants were determined for each component and for each whole coal or fraction. Arbitrary reactivity indexes were calculated by dividing by 100 the sum of the products of the percent of each component in the coal and its specific reaction rate constant. The resulting figure was an average reactivity index for each coal or fraction. Weighting the reactivity indexes for each fraction by the percent of the fraction in the coal gave a reactivity index for each whole coal which could be compared to that calculated directly from the whole coal analysis. If oxidation analyses really delineate definite physical entities within the coal, or even definite groups of similar entities, reconstituted analyses calculated from fraction analyses should check closely those made of the whole coal. It probably is true that optical methods identify and describe a greater variety of components than do chemical methods and that variations are wide in the appearance and quantity of those components identified optically. Chemical methods based upon differences in oxidation reaction rates would of necessity be less discriminating, as between similar components, than would optical methods. The procedures followed for oxidizing the samples, analyzing the residues, plotting and calculating the percentage of each component, and calculating its specific reaction rate constant have been fully described.'-' In brief the method originally proposed by Fuchs et al.1 for the determination of fusain consists of the oxidation of small samples of coal in boiling 8N nitric acid in a condenser-fitted flask. After boiling for periods of 1/2 to 4 hr, the unoxidized residue is filtered and washed. The washed residue is treated with normal sodium hydroxide, diluted, and allowed to stand for several hours. The resulting brown liquor is removed, and the filtered residue dried, weighed, ignited, and weighed again. The ash-free residue is expressed as a percent of original dry, ash-free coal. The percent residue is plotted against time, and the extrapolation of this line to zero time gives the percentage of dry ash-free fusain present in the original sample. The shape of the resulting time plots has been explained' by the assumption that they are the result of two different types of reaction, the first part representing a first order reaction with rate a func-

Jan 1, 1956

By R. E. Head

UNDER existing economic conditions, the treatment of gold ores occupies an outstanding position in metallurgical activity. The increased price of gold has automatically brought about a reclassification of old dumps and low-grade orebodies, and many that formerly were considered valueless are now being vigorously investigated and worked. This situation has developed problems that have taxed the ingenuity and ability of metallurgists to the utmost. Some gold ores give a high extraction of gold by standardized methods of treatment; other ores of apparently similar character yield but a relatively small percentage of their gold when treated by the same processes.

Jan 1, 1936

By M. Baeyertz

SINCE 1915 many papers and books have covered industrial applications of X-rays from various angles. Two of the more recent are a paper by Fink and Archer1, which describes in detail the technique of radiography, and a paper by Clark2, which embraces the whole field of X-ray metallography. This paper, therefore, is confined to work of the X-ray Laboratory of the Western Electric Co., which naturally divides into two categories: radiography and diffraction patterns of various types.

Jan 1, 1930

By R. C. Schmidt, B. E. Kennedy

The Mont Klahoyo magnetite deposit is located about 600 km (373 miles) northwest of Abidjan, Ivory Coast. During an exploration period ending in 1977 an international joint venture group investigated the deposit and proved reserves of 670 Mt (739 million short tons) grading 36% iron. The deposit occurs at the northeast end of the Baoubly-Kiriao chain of Precambrian iron formations with associated amphibolites, pyroxenites, and gneisses of the Liberian Shield. The ore body is represented by a highly metamorphosed banded quartz-magnetite iron formation with alternating beds of iron silicates and quartz-magnetite. Amphibolite-pyroxenites and sillimanite-cordierite-garnet gneisses form hanging and footwall rocks. The iron formation has been folded into an elongated, overturned 2-shaped major drag fold with axes trending and plunging approximately northeast. Beds are vertical or dip steeply to the southeast. The ore zone has an average thickness of 130 m (427 ft) and outcrops intermittently over a distance of approximately 5.5 km (3.4 miles). Based upon detailed studies of drill cores and the results of ore dressing test work, eight stratigraphic units, identified as K- 1 to K-8, are recognizable in the iron formation. Four interbedded units are low grade silicate zones (silicate facies) while the remaining quartz-magnetite units are oxide facies, representing the important Mont Klahoyo deposit ores. Ore-bearing "K" units are subdivided further into 11 ore types, based upon their specific lithologies, iron content, and concentration characteristics. Identification of these ore types proved particularly useful to mine planning and flowsheet design. A cap of oxidized material overlies the primary quartz- magnetite iron formation, but no enrichment has occurred. It is thought that the Mont Klahoyo iron formations were deposited chemically in a volcanic environment as a siliceous iron formation with volcanism the primary source of iron and silica. Metamorphism converted the siliceous iron formation to a coarse-grained, quartz-magnetite-silicate iron formation.

Jan 1, 1983

By John V. Beall

Thai means free. Historically accurate, as the country has never been subjugated by foreign occupation, the name "The Land of the Free" also seems to fit the attitude of the people. At the Bangkok airport, without so much as a kopkhun (thank you), travelers are found behind, beside and in front of ticket counters. A pretty Thai face on TV calls flights in English and Thai. Baggage disappears with alarming rapidity and your reporter and spouse despaired of ever being reunited with it. But at the entrance, all the parts came together and there was even a limousine from our hotel, The Oriental. Driving downtown English style, we noted that there were four lanes of traffic occupying the space we would allow for three lanes. Motorcycles and enclosed three-wheel motorcycle taxis were much in evidence, but the occasional water buffalo held up the slow lane. In the city, men wore European-type slacks and shirts but the women were colorful in traditional ankle-length wraparound skirts.

Jan 1, 1970

Albin, B. R. Billings, Mont. '28 Amster, Nathan L 25 Broad St., New York, N. Y. '28 Bache, Jules S 42 Broadway, New York, N. Y. '28 Barrett, C. P 5338 Harper Ave., Chicago, Ill. '28 Baum, Frank G., Cons. Hydro-Electric Engr Cassel, Shasta Co., Cal. '28 Bayless, William S Russ Bldg., San Francisco, Cal. '28 Bean, Louis H., V.P., Dwight P Robinson & Co., Inc. 125 E. 46th St., New York, N. Y. '28 Beatty, Ross J 1105 First National Bank Bldg., Chicago, Ill. '28 Benwell, Oswald F 110 Gilpin St., Denver, Colo. '28 Beymer, Albert S., V P., Keystone National Bank Pittsburgh, Pa. '28 Blumenthal, Hugo 44 Pine St., New York, N. Y. '28 Boettcher, Charles Ideal Cement Bldg., Denver, Colo. '28 Bowlus, Thomas H Iola, Kans. '28 Brown, Colvin B. .. Chamber of Commerce, Washington, D. C. '28 Burt, Maxwell Struthers Southern Pines, N. C. '28

Jan 1, 1923

By G. Willard Quick, John R. Freeman

Jan 1, 1930