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By H. A. Coy

THE Mascot mines of the American Zinc. Co. of Tennessee are situated at Mascot, Tenn., 14 miles northeast of Knoxville, on the Southern Railway. The district is centrally located in the Great Valley, or Appalachian Valley Province. Prior to 1900, a small output of zinc was obtained from oxidized ore mined in open pits. In 1900, a shaft was sunk to sulfide ore, and in 1903, a second shaft was put down, neither being as deep as 200 ft. The American Zinc Co. of Tennessee began drilling in 1911, and outlined an ore body to which its No. 1 shaft was sunk, to a depth of 365 ft. Since that time, the American Zinc Co. of Tennessee has been the only operator in. the district. The Federal mining laws have never been in operation in Tennessee and mining lands are as irregular in boundary and area as farm lands. Ownerships are generally held in fee. In most cases the surface and mineral rights, are transferred together. Electric power is supplied at 66,000 volts by the Tennessee Power do, from a hydro-electric plant at Parksville, Polk County, Tenn., 100 miles from Mascot. No other power is used, but an emergency steam plant is held ready in case of interruption of service. Labor is all native and non-union. Negroes are employed for most of the shoveling, and for a few miscellaneous jobs, but for almost, no other work.

Jan 9, 1924

By Max Roesler

Page I. Introduction........................... 78 Location.......................... 78 Scope of Work and Acknowledgments.............. 79 History and Mining...................... 80 I1. Topography and its Interpretation................. 80 III. Petrology............................ 82 Sedimentary Rocks...................... 82 Description....................... 82 Age.......................... 84 Igneous Rocks........................ 85 Diabasic Rocks..................... 86 Dioritic Rocks...................... 87 Granitic Rocks...................... 88 Later Dike Rocks.................... 88 IV. Areal Geology.......................... 88 Rock Types Found in the District............... 88 Distribution of the Various Rock Types............. 89 Surface Distribution................... 89 Vertical Distribution................... 90 Causes of Present Areal and Vertical Distribution of the Various Rock Types..................... 91 Faulting...................... 91 Magmatic Differenti~tion............... 91 Tilting........................ 95 Erosion....................... 96 V. General Description of Ore Deposits................ 96 Nature of Ore ........................ 96 Shap~ and Size of Orebodies.................. 96 Geologic Position....................... 97 Mineralogy......................... 98 Distribution....................... 98 Interpretation...................... 99 Superficial Alteration................... 102 VI. Genesis of the Ore Deposits.................... 104 Previous Theories...................... 104 J. P. Kimball...................... 104

Jan 1, 1917

By M. G. Corson

INFORMATION regarding the use of manganese alloys has hitherto been incomplete and available only from widely scattered sources. This paper attempts a systematic description of properties .and uses of alloys other than manganese bronze, manganin and duralumin, which are probably the only non-ferrous alloys associated with manganese in the minds of most metallurgists.1 PROPERTIES OF MANGANESE Manganese can react either acid or basic; it is hard to obtain in the pure state; it has two different crystalline lattice structures, both of the cubic system, one stable above 850° C. and the other below 650° C., both coexisting in the intermediate range. Although the commercial product is hard and brittle, the pure metal seems to be ductile. In fact Zhemchuzhny, in Russia, was able to obtain ductile manganese and draw it to fine wires by the simple expedient of adding about 3 per cent. copper to the alumino-thermic product. Copper most probably brings the silicides, aluminides, nitrides and carbides present in the commercial product into a much less harmful form of distribution. One industrial use that can be foreseen for wrought manganese articles is as anodes for electrolytic processes in sulfate and nitrate solutions, particularly with high voltages. A practically insoluble skin of manganese peroxide is likely to form in such cases and an insoluble and strong anode material will be available.

Jan 1, 1927

By Otto C. Kopp, Thomas B. Crattie, Dennis R. Owen

Whole-rock analyses of limestones, fine-gralned dolostones and coarser-grained dolostones adjacent to mineralized breccias (Coy mine, Mascot-Jefferson City district) were compared with similar lithologies adjacent to apparently non-mineralized breccias at the new Thorn Hill section located approximately 39 km north of the Coy mine. Specimens were analyzed for Ca, Mg, Si, Al, K, Fe, Mn, Sr, Br, C1, S, Ti and P using X-ray fluorescence analysis. The concentrations of the major and most minor elements for Thorn Hill specimens fall within the range of concentrations for Coy mine specimens; however, significant differences (probability < 0.05) were noted for Fe, C1 and Br for fine-grained dolostones and for MgO, Fe and Mn for the coarser-grained dolostones. No significant differences were detected for the limestones.

Jan 1, 1985

Jan 1, 1958

By C. M. Young

The following paper has been prepared with the object of placing on record in the Transactions some facts concerning the present condition and future prospects of the coal industry of Illinois. In presenting it, the writer wishes to say that a considerable amount of the material contained is taken from the publications and records of the Illinois Coal Mining Investigations, the annual Coal Report of the State Mining Board, and the work of the State Geological Survey. Coal Beds and Mining Methods According to the latest maps of the State Geological Survey, there are only 19 of the 102 counties of the State some portion of whose territory is not within the borders of the coal measures. If outlying areas in Calhoun and Whiteside Counties are considered, the number is reduced to 17. This does not mean that all of the 85 counties that are partly or wholly underlain by coal measures will become producers, as there are some portions of the State in which the coal does not occur in beds of such thickness as to warrant the hope that it can be mined. The mining of coal is widespread, however, for in 1916 there was production from 61 of the 102 counties of the State, There seem to be no cases in which operations will be limited by depth, as none of the coal measures lie at depths much greater than those at which it has been proved that coal may be profitably mined in this field. In fact, the deepest shaft reaching a bed of bituminous coal in the United States is located in this State at Assumption, where coal only 3 ½ ft. (1.07 m.) thick is worked at a depth of 1004 ft. (306 m.). The coal beds occur in the form of a basin which is deepest along a line extending through the central part of the State and bearing a little west of north. The northern, western and southern borders of this basin lie within the boundaries of the State, but on the eastern side the Illinois field is continuous with the Indiana field. The glacial drift covers all except the extreme southern end of the State and the visible outcropping

Jan 1, 1918

By R. E. Carter, C. Wagner, F. D. Richardson

By means of inert markers of radio-platinum, it has been shown that cobalt metal oxidizes by out-ward diffusion of cobalt atoms through the oxide. Oxidation rates have been measured at various temperatures and oxygen pressures and have been found to agree with the rates calculated from the Wagner equation and the authors&apos; values for the diffusion coefficient of cobalt in the oxide. The distribution of radio-cobalt in growing oxide loyers has been accurately measured and found to be different from that predicted from the Wagner oxidation theory. Attempts have been made to measure the change of lattice parameter of the oxide with composition. SEVERAL investigators have shown that cobalt metal oxidizes according to the parabolic law,1-3 but no detailed study has been made of the oxidation mechanism. Cobaltous oxide has a metal-deficient lattice, but the defect concentration which is dependent on the oxygen pressure is only approximately known.&apos; From the similarities in the structures of "CoO" and "FeO" and the rate laws governing the oxidation of cobalt and iron, Gulbransen- as suggested that cobalt, like iron," oxidizes by diffusion of cobaltous ions through the oxide layer. To substantiate this hypothesis, he has attempted to measure the oxidation rate of cobalt as a function of the oxygen pressure but has been able to report only that the rate depends on a "small" power of the pressure. On the other hand, Preece," Valensi,&apos; and Arkharov&apos; all have suggested from indirect evidence that oxygen diffuses through the COO to the metal-oxide interface. The present authors, in a previous paper,&apos; have shown that the rate of diffusion of cobalt in cobaltous oxide is dependent on the oxygen pressure. In that investigation, they also found that cobaltous oxide disks made by complete oxidation of cobalt metal were porous at their centers (Fig. 5L, ref. 4). Both these facts strongly suggest that oxidation of the metal proceeds via outward diffusion of cations. In order to establish the mechanism unequivocally, oxidation experiments were made with inert radioactive platinum markers, and the dependence of oxidation rate on oxygen pressure was measured. In addition, an attempt was made to determine the form of the cation vacancy gradient, which the marker experiment showed must exist across a growing oxide layer. This was done by depositing radioactive Co on the surface of a cobalt disk and then measuring the tracer distribution across the oxide layer produced by partial oxidation of the metal. Finally, an X-ray examination was made in an attempt to find the expected change of lattice parameter of COO with oxygen pressure. Experimental The apparatus and materials used were substantially the same as those previously described by the authors.4 Marker Studies: The use of inert markers to follow oxidation reactions was first attempted by Pfeil" in 1929, and radioactive markers have recently been used by Davies et al.&apos; In the investigation reported here, the markers were applied as an (NH4)2PtCI6 slurry in several thin streaks across both faces of four disks of cobalt metal 1 mm thick and 14 mm in diameter. The disks were then oxidized almost to completion at 1200°C in pure oxygen. After oxidation, they were mounted and sectioned and auto-radiographs were taken to locate the markers. Oxidation Rate: The oxidation rate of cobalt was measured at 1148°C at oxygen pressures ranging from 0.0055 to 1.0 atm and at 1000°, 1148", and 1350°C under 1 atm of oxygen. The rate was deter-

Jan 1, 1956

By Neils Hansen

The microstructure of dispersion-strengthened aluminum aluminum-oxide products containing from 0.2 to 4.7 wt pct of aluminum oxide has been examined by optical and transmission electron microscopy, and the flow stress has been determined at room temperature and at 400C by tensile testing. Products were examined as recrystallized and as high-temperature extruded, and the microstructures consisted of a fine dispersion of oxide particles in a matrix divided by respectively recrystallized grain boundaries and subgrain boundaries. The flow stress (0.2 pct offset) at room temperature of recrystallized dispersion strengthened aluminum aluminum-oxide products is the superposition of dispersion strengthening and grain boundary strengthening. This superposition has been found to be linear. The flow stress (a) can be related to the grain size (t) by the Petch equation: ing content of oxide and k is a constant independent of the oxide content. For extruded products a similar relation has been found by replacing the grain size by the subgrain size. The k-value is of the same order for the two types of structure, which shows that the subgrain boundaries are as effective slip barriers as grain boundaries. Tensile testing at 400C of re-crystallized and extruded products shows that oxide dispersion strengthening is very effective, whereas the strengthening effect of grain boundaries and subgrain boundaries is small. THE microstructure of dispersion-strengthened products consists of hard particles finely distributed in a metal matrix. The strengthening effect of the dispersed phase has been fairly well established,1 and it has been found that the size and volume fractions of the dispersed particles are important structural parameters. However, in many dispersion-strengthened products which have been worked and heat-treated during manufacture the matrix is divided into well-defined grains or sub-grains, which may also have a strengthening effect. A model of the matrix strengthening in dispersed products worked during manufacture has been proposed,2 introducing the energy of the structure as a strengthening factor, especially at low temperatures. A difficulty in this model is, however, to relate this (stored) energy to the structural parameters directly observable as for instance grain size. The strengthening effect of the matrix grain size after recrystallization has been in- vestigated for nickel-thoria (TD-Nickel) products3 and for copper aluminum-oxide products. Conclusive results were, however, not obtained as the grain size of TD-nickel was constant. 5 to II , after recrystallization at temperatures from 700 to 1200°C and as the copper products containing 5 to 1 wt pct of aluminum oxide could not be recrystallized even after severe cold reduction and heat treatment at 1050C. For aluminum aluminum-oxide products containing from 1 to 5 wt pct of aluminum oxide it has been shown that the tensile strength at room temperature decreases when an extruded product is cold-worked and recrystallized. The matrix in the extruded products is divided into well-defined subgrains of micron size, and as the grain size of the recrystallized products is about two orders of magnitude higher, it is obvious that grain boundary strengthening occurs. Preliminary results8 have indicated that the flow stress containing no grain boundaries, A is a constant and t is the subgrain size. At elevated temperatures the effect of boundaries is more complex; it has been shown11 that recrystallized products having an oxide content of about 3 wt pct are more creep resistant than extruded material in the temperature range 400° to 600°C, whereas on application of a higher strain rate the tensile flow stress (0.2 pct offset) is higher in extruded than in recrystallized aluminum—5 wt pct aluminum oxide products at temperatures from room temperature to 427°C (800), Finally it has been shown12 that the Brinell hardness at 350°C of extruded products having about the same content of aluminum oxide increases with decreasing grain size, determined by X-ray line-width measurements. The present study was undertaken to obtain a quantitative relationship between the tensile strength and the grain size of aluminum aluminum-oxide products in the recrystallized as well as in the extruded state. The tensile testing was performed at room temperature and at 400uC. The grain size of the recrystallized products was varied by changing the degree of cold-work preceding the recrystallization heat treatment. In extruded products grain (or subgrain) size variations were obtained by high-temperature heat treatment after extrusion. EXPERIMENTAL a) Materials. Aluminum aluminum-oxide products have been manufactured by consolidation of aluminum powder covered with a layer of aluminum oxide formed during powder manufacturing. The products examined were manufactured from atomized powder containing

Jan 1, 1970

By William Sharp

Discovery of new ore in the Eureka district, Nevada, as a result of bold and persistent exploration based on a geologic interpretation of structure has recently aroused wide comment in mining circles. It may therefore be of interest to the profession to have a summary of the historical background and an account of the recent program of development. The mines of Eureka, discovered in the late 1860&apos;s, were the first important silver-lead mines in the United States. They have a production record of more than fifty-one million dollars.&apos; After the ore bodies were apparently bottomed in the 1880&apos;s, repeated attempts to find new ore were unsuccessful until 1940, when a diamond-drill hole cut a 40-ft width of sulphide ore 1409 ft below the 841-ft level of the Locan shaft. The next hole cut 30 ft, of ore and three additional holes drilled in 1943 and 1944 showed the ore body to be continuous, Shaft sinking to reach and open up the ore body has been in progress since 1945. Geology Stratigraphy The ore in the Eureka district occurs in a series of Cambrian sediments which is exposed through a thickness of over 6000 ft. The stratigraphic column is as follows:2 Thickness. Ft Ordovician : Pogonip limestone (upper part). Thin bedded limestone with some chert. Upper Cambrian: Pogonip limestone (lower part). Thin-bedded limestone (with shaly limestone and chert).... 425 + Dunderberg shale. Shale (clay and calcareous shale) and thin-bedded limestone............. 34°+ Hamburg dolomite. Dolomite and limestone.................... 900+ Middle Cambrian: Secret Canyon shale. Shale and thin-bedded limestone........ 1,035 Geddes limestone. Carbonaceous, flaggy limestone with some shale partings................ 335 Middle (?) and LoweR Cambrian: Eldorado dolomite. Dolomite and limestone.................... 2,000 Lower Cambrian: Prospect Mountain quartzite. Quartzite with occasional intercalated conglomerate and shale 1,660+ The Prospect Mountain quartzite has been subdivided into two formations: Upper part, Pioche shale. Shale, quartzite with some intercalated limestone (Lower Cambrian fossils)-200 ft. Lower part, Prospect Mountain quartzite proper- 1,460Sft. Total thickness................ 6,695 + Much the most productive of these formations has been the Eldorado dolomite, which yielded more than $42,000,000 at Ruby Hill and an additional amount

Jan 1, 1949

By William Sharp

Discovery of new ore in the Eureka district, Nevada, as a result of bold and persistent exploration based on a geologic interpretation of structure has recently aroused wide comment in mining circles. It may therefore be of interest to the profession to have a summary of the historical background and an account of the recent program of development. The mines of Eureka, discovered in the late 1860&apos;s, were the first important silver-lead mines in the United States. They have a production record of more than fifty-one million dollars.&apos; After the ore bodies were apparently bottomed in the 1880&apos;s, repeated attempts to find new ore were unsuccessful until 1940, when a diamond-drill hole cut a 40-ft width of sulphide ore 1409 ft below the 841-ft level of the Locan shaft. The next hole cut 30 ft, of ore and three additional holes drilled in 1943 and 1944 showed the ore body to be continuous, Shaft sinking to reach and open up the ore body has been in progress since 1945. Geology Stratigraphy The ore in the Eureka district occurs in a series of Cambrian sediments which is exposed through a thickness of over 6000 ft. The stratigraphic column is as follows:2 Thickness. Ft Ordovician : Pogonip limestone (upper part). Thin bedded limestone with some chert. Upper Cambrian: Pogonip limestone (lower part). Thin-bedded limestone (with shaly limestone and chert).... 425 + Dunderberg shale. Shale (clay and calcareous shale) and thin-bedded limestone............. 34°+ Hamburg dolomite. Dolomite and limestone.................... 900+ Middle Cambrian: Secret Canyon shale. Shale and thin-bedded limestone........ 1,035 Geddes limestone. Carbonaceous, flaggy limestone with some shale partings................ 335 Middle (?) and LoweR Cambrian: Eldorado dolomite. Dolomite and limestone.................... 2,000 Lower Cambrian: Prospect Mountain quartzite. Quartzite with occasional intercalated conglomerate and shale 1,660+ The Prospect Mountain quartzite has been subdivided into two formations: Upper part, Pioche shale. Shale, quartzite with some intercalated limestone (Lower Cambrian fossils)-200 ft. Lower part, Prospect Mountain quartzite proper- 1,460Sft. Total thickness................ 6,695 + Much the most productive of these formations has been the Eldorado dolomite, which yielded more than $42,000,000 at Ruby Hill and an additional amount

Jan 1, 1949

By J. R. Thoenen

THE consensus of opinion in the published literature on. Grecian magnesite is that it has been formed by alteration of the serpentine, which in turn was itself a product, of metamorphism from the original olivine intrusion. The general opinion seems to be that the magnesite was formed by descending waters heavily charged with CO2. Inasmuch as this opinion is held by engineers far better qualified than I to speak authoritatively on this subject, I hesitate to dispute that theory. However, certain occurrences coming under my observation do not, to me at least, seem to-entirely substantiate this theory. LOCATION Most of the Grecian magnesite comes from the Island of Euboea, although more recently some deposits have been opened on the mainland near the City of Saloniki, which prior to the war was Turkish. The island, comprising a state or province in the Greek political structure, is roughly 110 miles long and varies from 10 to 30 miles in width. It lies off the east coast of the Greek peninsula in the AEgean Sea with its long axis extending in a northwest-southeast direction. It is separated from the mainland by a long narrow arm of the sea known as the Atalanti Canal. Chalkis (Halkis), the capital on the west coast of the island, is the northern terminus of a branch of the state-owned railway and is connected with the mainland by a single-span, movable, highway bridge, roughly 150 ft. long.

Jan 1, 1928

By B. C. Burgess

IN the first edition of this volume,44 feldspar was introduced as "the I commonest mineral of the crystalline rocks," usually in small grains associated with other minerals and commercially produced only from pegrnatites. Now other crystalline rocks, such as alaskites and granites, have become present or potential sources of feldspar. In addition, feldspar has encountered very vigorous competition from such substitutes as nepheline syenite and aplite. COMPOSITION AND PROPERTIES The feldspars form a group of which the principal species are orthoclase, microcline, albite, and anorthite. These are aluminum silicates of potassium, sodium and calcium. There are also a barium feldspar, celsian, and barium orthoclase feldspar, hyalophane, rarely found and of no commercial importance. None of the minerals in the feldspar group are found pure or nearly pure. The potash feldspars, orthoclase and microcline, nearly always contain some albite (soda microcline, an- orthoclase); the soda feldspars usually contain some anorthite (lime feldspar). There is a series of soda-lime feldspars known as plagioclase in which the albite and anorthite molecules replace each other in varying proportions from albite through oligoclase, andesine, labradorite, and bytownite to anorthite. Theoretical chemical composition of the principal feldspars is given in Table 1. The Whiteware Division of the American Ceramic Society sub- mitted a list of definitions of ceramic terms, in April 1947, for use in technical literature. For feldspar it gives: "A group of igneous minerals consisting chiefly of the aluminum silicates of potash, soda and lime, in which one base generally predominates." Commercial feldspars are intergrowths of at least two species of feldspar, which occur associated with one or more accessory minerals such as quartz, muscovite, biotite, garnet and tourmaline as well as with small but varying proportions of the decomposition product, kaolinite. An intergrowth of quartz and feldspar frequently contains

Jan 1, 1949

INTRODUCTION The regional characteristics of porphyry copper deposits in South America southward from Pantanos and Pegadorcito, Columbia, will be summarized. The age of formation of deposits spans the period from the Permian to the present. Where possible, the general characteristics and the individual structural features of the deposits are integrated into the plate tectonic model. Individual deposits cited in this chapter, located in Fig. 1, are the best known and most fully described, and form the Andean copper belt (Peterson, 1958). Smaller porphyry copper deposits fall both east and west of the line of large, high grade deposits (e.g., Chuquicamata and Toquepala) that make up the spine of this belt. Most of those smaller deposits (e.g., Mi Vida [Koukharsky and Mirre, 19761) are omitted from Fig. 1 and Tables 1 and 2, however. Neither the Andean orogen nor the individual deposits within it are as well de- scribed in the literature as are their counter- parts in the Cordilleran orogen of North America. Therefore, generalizations relying on regional geologic mapping, geophysics, and isotopic geochemistry lack details pertinent to this type of deposit in the Cordilleran orogen. The South American porphyry copper province has been described by Hollister ( 1974) to include most of the Andean orogen excepting the tin province of Bolivia. Porphyry copper deposits have not been commonly found within the tin belt, although copper-tin (e.g., San Rafael, Peru) and copper-tungsten (e.g., Llamuco, Chile) de- posits are known. James (1971) shows the depth to the Moho to be appreciably greater where the tin belt exists, but disclaims any genetic significance from the coincident appearance of the tin-tungsten province and the inhibition of porphyry copper development where the sialic crust thickens. Dates on tin mineralization in this belt (Clark and Farrar, 1973) are similar to some dates for porphyry copper mineralization known else- where in the Andean orogen. It seems that some mechanism is needed to explain the geographic separation of porphyry copper- molybdenum and simultaneous tin-tungsten- molybdenum metallization within the same tectonic system and appearing at similar distances from the trench. The thickened crust of the tin belt is one of the few known differences. Tables 1 and 2 list some of the most important porphyry copper deposits explored to date, but do not include Antaminas, Peru. or a number of other large skarn deposits

Jan 1, 1978

By H. D. Kynor

By the term mechanical mining is meant that operation, or series of operations, that replace the hand methods of mining. The first undercutting machine to operate in anthracite was placed in the Butler mine of the Hillside Coal and Iron Co., Dec. 23, 1910, by the Sullivan Machinery Co. The first Jackhamer used in the anthracite field was installed at the Wadesville colliery of the Philadelphia & Reading Coal and Iron Co. in Oct., 1912, by the Ingersoll-Rand Co. The first longwall conveyor was installed at the Dodge mines of the Delaware, Lackawanna, & Western Coal Co. in March, 1912. The first mechanical scraper equipment was installed in the Seneca mines of the Lehigh Valley Coal Co. in January, 1914. The amount of anthracite mechanically mined since the first mining machine was installed in 1910" is as follows: Penna. Coal Co. D. L. & W.. ScRanton Temple Hudson YeaR and Hill- Tons Coal Co., Coal Co., Coal Co., Total, side Coal Tons Tons Tons Tons and Iron. Tons 1920................ 372,737b 367,000d 322,892 74,127 371,878 1,508,634 1919................ 950,786 no record 306,616 81,575 319,356 1,658,333 1918................ 917,778 744,966 24,880 44,756 288,781 2,021,161 1917................ 757,940 838,800 5,050 57,279 164,180 1,823,249 1916................ 286,780 860,663 13,960 114,173 101,475 1,377,051 1915................ 428,819 592,169 8,253 1,029,241 1914................ 219,188 153,896 373,084 1913................ 171,505 1912................ 124,267 124,267 1911................ 40,319 40,319 1910................ 1,184 1,184 a A slightly greater production was obtained than here indicated, as the tonnage from individual operations is not shown. b Decrease due to strike conditions in 1920. c Does not include tonnage of D., L., & W. d D., L., & W. decrease in 1920 due to having fewer mining machines in operation. There are about 150 undercutters in use in the anthracite region, 80 mechanical loaders, and 10 longwall conveyors.

Jan 1, 1922

By R. L. Loofbourow

Trends in the metal mining industry were definitely down in 1954. With a record in 1953 of $1.8 billion output, the last year dropped to $1.5 billion, the lowest value since 1950. The decrease in iron ore production alone accounted for at least 10 pct of the decline. PROBABLY more than any previous year, political debates of 1954 marked a new high for the mining industry. Lead and zinc prices gave forth with minor rallies producing no real improvements. An anticipated drop in copper prices never came to be. Early in the year arguments for more free trade versus tariffs to restrict imports were voiced eloquently by Charles P. Taft, president, Committee for a National Trade Policy, and Andrew Fletcher, president, St. Joseph Lead Co.

Jan 3, 1955

By Cyril Stanley Smith, W. Earl Lindlief

A study of the mechanical properties of the alloys of copper and silver led to the discovery that the solubility of silver in copper was greatly different from that generally supposed, therefore some work was done to determine the solubility with greater accuracy than had previously been achieved. After the work had been completed, two papers were published&apos; giving solubility figures which agreed closely with one another and with the work described herein. A detailed comparison of that work with the present will be given later. Preparation of Allots The copper used in making the alloys was electrolytic ingot of high purity. The silver was prepared by precipitation as chloride from nitric acid solution, followed by fusion of the washed precipitate with sodium carbonate and potassium nitrate. This method gives metal containing at least 99.99 per cent silver. The copper was first melted under charcoal in a small electric resistance furnace and the silver added as pure silver, it being unnecessary to make any intermediate alloys. After thorough stirring the metal was poured into a mold of suitable form. The alloys contained between 0.008 and 0.015 per cent of oxygen. Small amounts of oxide were visible under the microscope, but it is not believed this would have much effect on the results. Copper-silver alloys are notorious for segregation, consequently a few experiments were carried out to find a form of casting with as little segregation as possible. A mold 6 in. long and 1/2-in. dia. was first used, and an alloy nominally containing 5 per cent silver was cast in it, while some of the same alloy was poured directly into water to obtain the maximum rate of cooling possible. Analyses were made both on this sample and on turnings from the top and bottom of the 1/2 in. dia. cast-ing, the turnings being separated into three parts according to the position

Jan 1, 1932

By W. E. Keck

THERE is a considerable tonnage of iron ore in the Menominee Range Michigan that is unsalable only because it has too large a content of sulphur. Beneficiation of such ore is economically desirable, as a rela-tively large quantity of finished concentrate would be obtained (deleteri-ous sulphur mineral content being generally less than 5 per cent) and because large blocks of such ore have been developed incidentally during search for low-sulphur ore. Research on the flotation beneficiation of these high-sulphur ores consisted of: (1) a study of the flotative properties of the principal min-erals in a nearly puree state, (2) flotation of synthetic mixtures of these pure minerals and (3) application of this experimental information to samples of the ores. Gypsum in iron ores is extremely deleterious; but when sufficiently free from impurities it is a valuable commodity. In 1934, the United States produced 1,500,000 tons of calcined and uncalcined gypsum valued at $13,700,000&apos;. Of this quantity and value, Michigan produced approxi-mately 19 per cent4. Thus this investigation may also prove to be of interest in connection with the gypsum industry if minerals separation, such as flotation, becomes necessary in the future processing of gypsum. Data on the flotative properties of gypsum would also be of interest to the science of flotation because such information has been extremely limited. The technical literature reveals one reference to the flotation of gypsum, in which was discussed the use of the mineral, with several others, to determine the relation between the floatability of minerals and the pH of the flotation solution2. This investigation necessarily was not comprehensive in regard to gypsum, but it did show that the mineral could be floated with oleic acid under varying pH conditions.

Jan 1, 1937

By J. A. Herbst, D. W. Fuerstenau

This paper examines the zero order production phenomenon in the context of the size discretized batch grinding model. A restrictive interrelationship between the selection and breakage parameters of the model, which is mathematically sufficient to ensure zero order behavior, is delineated. Based on this interrelationship, a scheme is developed for predicting the values of the selection and breakage parameters for all size fractions from a minimum of experimental data. To test this scheme, dolomite was ground in a laboratory batch ball mill. Successful simulation of the comminution behavior of this system was achieved using the batch grinding model with the parameter values obtained from the proposed scheme. Historically, a preponderance of comminution research has centered on attempts to relate breakage energy to the performance of comminution machines. Concomitantly, grinding data were interpreted almost exclusively in terms of inherently empirical energy-size reduction relationships1-3 or "laws of comminution"4- 6 which were based on highly oversimplified descriptions of the fracture process. In some instances, these relationships provide a crude basis for the correlation of experimental data, but, invariably, this approach is inadequate for meaningful process simulation. The control and optimum design of comminution circuits require a mathematical model capable of depicting the size reduction behavior of every size fraction for grinding conditions of technological importance. Energy-size relationships do not provide this detailed information. For example, an energy-size analysis for batch ball-milled dolomite has recently been completed in the authors&apos; laboratories.7 This analysis provided a satisfactory correlation between the hypothetical size modulus, which characterizes only the finer portion of the size distribution, and the input energy. However, this relation did not constitute an adequate description of the complete system. In general, one of two distinct viewpoints toward simulation has been adopted in recent comminution research. The first approach focuses on the fracture of single mineral specimens, with the essential aim of representing the over-all process in terms of the breakage characteristics of individual particles and the characteristics of the stress field which the particles experience within the particular size reduction device. As illustrated by Harris&apos;s review,&apos; the actual incorporation of single-specimen fracture information into a description of the behavior of a multiparticle comminution system has seldom been attempted. The only model to accomplish this incorporation was the one developed by Schönert.8 The Schonert model treats single-passage grinding machines in terms of a distribution of effective loads acting on a particle, a distribution of required particle breakage energies, and the breakage product distribution. However, the use of single-particle fracture behavior to derive models of the size reduction process is at present limited to machines in which the particle residence time is approximately equal to the time required to apply stress. As a result, Schönert&apos;s analysis cannot be used to advantage to simulate the complex environment which prevails within a tumbling mill. For multiple-passage systems a second approach to the description of comminution processes has been more fruitful. This approach entails the formulation of a mathematical model which is phenomenological in nature in that it lumps together the entire spectrum of stress-application events which prevail in a system under a given set of operating conditions. The appropriately defined average of these individual events is then considered to characterize the over-all breakage properties of the device. Thus, to analyze the performance of a tumbling mill, the manner in which the particles of a particular size (or size fraction) are stressed need not be distinguished. Instead, a single parameter is assumed to represent the resistance of that size to fracture, given the average grinding environment which exists in the mill. The isolation of such a parameter and a related set of quantities, which constitute the breakage product size distribution for the average event in this size fraction, allows the formulation of physically meaningful descriptive equations capable of yielding precise and detailed information for simulation.

Jan 1, 1969

THE subcommittee on Coal Mining, since its appointment, has been engaged in collecting data about subsidences in coal mines in this country, and it now feels that almost all of the available data about occurrences of this sort in bituminous mines has been collected. As most of the bituminous seams are nearly level, the records obtained give the problem in its simplest form, without complications due to the pitch of the seam. Similar data is being compiled for the anthracite regions and it is hoped that this will be ready for the 1927 meeting. Copies of the questionnaire, Appendix A, were mailed to all of the coal operators&apos; associations, to most of the large operating companies and to many engineers, with the request that any data on the subject be returned to the committee, or that advice of any subsidences known be given. The replies to most of the questionnaires were general only, although some specific cases were given. Many of the companies were unable to reply to all questions, as they lacked the necessary data, but in nearly every case where accurate data was available, it was cheerfully furnished, and any additional information requested was secured. All specific cases of subsidence were followed up by correspondence, and in several cases by personal inspection. Figs. 1 to 31 were made from the information furnished. Table 1 gives measurements of elevations taken in one case at intervals from October, 1913, to May, 1918. With one exception, where the evidence cannot yet be released on account of a lawsuit, it is believed that the cases submitted with this report include practically all that have happened in bituminous coal mining in this country of which actual measurements were secured. Some of these have already been published in the excellent report by Young and Stoek,1 and some instances have been secured from other publications. In collecting these data, the subcommittee had the Engineering Societies Library extend the bibliography given in the bulletin mentioned above to date. This list is given in Appendix B.

Jan 2, 1926

By Charles Means

A THOROUGHLY modern coal-handling system has been installed at the Pittsburgh Terminal R. R. & Coal Co.&apos;s new No. 8 shaft, or Coverdale mine, about 11 mi. (17.7 km.) from Pittsburgh on a spur f the Montour R. R. The Pittsburgh seam, which is the one worked, is reached at a depth of 342 ft. (104 m.). Power is delivered to the mine at 22,000 volts over a transmission line of the bow-arrow type of construction. A private telephone line connecting the various mines and the main office in Pittsburgh is carried on the same poles. The high-tension line is brought to an outdoor, step-down, transformer substation, where three 833-kv.-a., single-phase, 60-cycle, oil-insulated, self-cooled transformers reduce the potential to 2300 volts. The transformers are protected by electrolytic, aluminum-cell lightning arresters, horn gaps, and choke coils. High and low-tension busses, together with fuses, choke coils and air-break horn-gap switches with their remote-control operating mechanism are mounted on a substantial structural-steel tower 25 ft. (7.6 m.) in height. MINE SUBSTATION The transformer substation is adjacent to a pressed-brick building that houses direct-current substation equipment together with switchboards, etc., for the control and distribution of power. This building also contains the hoist for the men and supplies.

Jan 9, 1921