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By C. C. Hagenbuch

Machine loading of coal into mine cars is increasing rapidly. Particular reasons for its use frequently apply to certain localities, but in general, it is profitable to install mechanical coal-loading equipment: (I) when existing hand-loading contract rates prevent further cost reduction; (2) when the height of the coal bed requires that either top or bottom must be taken to place cars in rooms; (3) when labor shortage or limited house-plant capacity prevents the production of desired tonnage ; (4) when tonnage requirements are in excess of possible hand-loaded production from developed areas; (5) when working places are scattered and it is possible to concentrate production, and therefore supervision, by the installation of mechanical equipment; (6) when rapid development is essential. Having decided to install loading equipment, the problem then arises as to what type is best adapted for a particular mine or coal bed, the choice lying between mobile track equipment, pit-car loaders, scrapers, shaker conveyors, belt conveyors and drag conveyors. MajoR FactoRs Influencing Choice of Equipment In determining the type of equipment to be used, the following major factors must be studied: Grades.—Adverse grades, while permitting other types of loading equipment to work successfully, may prevent the success of a shaker conveyor installation. Thickness of Bed.—The thickness of coal governs the choice of equipment. A machine that requires 5 ft. of head room should not be selected for a 3-ft. bed where otherwise it would be unnecessary either to brush top or to lift bottom. Nature of Pavement.—Soft or scaly bottoms are unsuitable for the use of any type of digging loader, shaker conveyors or scraper loaders. nigging loaders and scraper loaders scale the bottom, mixing it with the coal and causing preparation difficulties; shaker-conveyor drives frequently work themselves loose, destroying the conveyor alignment and creating maintenance problems. Nature of Roof.—With any type of loading machine, it is policy to obtain the maximum possible tonnage per move per set-up. This must

Jan 1, 1931

By A. S. Koster, G. D. Rieck

X-ray experiments were carried out to show the occurrence of cylindrical texture in drawn tungsten wire. Only a small amount of (110) (110) cylindrical texture could he found in wires of intermediate thickness, i.e., of about 1.5 mm diameter. DRAWN wires of tungsten and other bcc metals like iron and molybdenum show a well-established (110) fiber texture. Now it might be conceivable that in drawing radial stresses remove the randomness of the crystallites around the [110} axis, thus giving a fiber texture of higher symmetry. In the resulting so-called cylindrical textures a specified plane normal coincides with the radius of the wire. Several authors discuss the occurrence of cylindrical textures in bcc metals. ~ieck' found no cylindrical texture in drawn tungsten wires of 165 n diameter. Leber~ states that in tungsten wires of 3 mm diameter a cylindrical {100)(110) texture is developed, which is gradually converted to a normal fiber texture by subsequent drawing. He also reported a definite cylindrical texture at the surface of iron wires. Peck and Thomas3 observed a nonuniform mode of deformation of the grains in transverse sections of heavily drawn tungsten and iron wires. According to Bhandary and cullity4 a swaged iron wire has neither a perfect (110) fiber texture nor a perfect {100}(110) cylindrical texture. It is clear that the concept of cylindrical texture in bcc metals still lacks a firm experimental basis. Leber's eviden~e,~ which seems to be the strongest, rests upon qualitative interpretation of photographs. The appearance of the 110 and 200 lines on the photograph of 3-mm wire, however, can be very well attributed5 to a normal ( 110) fiber texture superimposed on random background; our Fig. 1, giving a Debye-Scherrer diagram of etched tungsten wire of 180 p, is free of cylindrical texture according to all authors, but is quite similar to Leber's diagram. It was therefore decided to use a different method of X-ray texture determination on tungsten wires of diameters where cylindrical textures may be expected.

Jan 1, 1965

By M. G. Benz, J. F. Elliott

The austenite solidus of the iron-carbon system has been determined using a series of diffusion couples, each of which consisted of a specimen of austenite held in contact with a melt saturated with austenite. After the equilibrium distribution of carbon had been established by diffusion at a specified temperature, i.e. the austenite specimen had become austenite of the solidus conzposition, the diffusion couple was cooled, sectioned and anazlyzed for carbon. The solidus was found to be a straight line: A revised iron-carbon temperature-composition diagram is presented, COMPOSITION has a marked effect on the temperature at which austenite begins to melt and the austenite solidus of the iron-carbon system describing this effect has been the subject of many investigations.1-10 The significant results of these investigations are presented in Fig. 1. The experimental methods and purity of the materials used in them are summarized in Table I. In plotting the data in Fig. 1 no attempt has been made to convert these results to the International Temperature Scale of 1948," except for the data of Adcock,5 as this conversion would do little to reduce the uncertainty that exists as to the position and shape of the solidus. A point of major concern in evaluating these data is that the alloys studied, except those used by Adcock, were not binary alloys of iron and carbon, Table I. Also, it would appear that several of the methods did not permit equilibrium to be established through the system being studied. All that can be said for the results of these investigations is that they indicate only approximately the location of the solidus with the uncertainty as to its location at 1 pct C being approximately 100°C. The current investigation was undertaken to provide reliable data by which the austenite solidus could be established. It was hoped that information on the liquidus also could be developed at the same time, but experimental limitations prevented this as austenite segregated from the liquid on cooling. After a careful study of possible experimental methods and extensive laboratory tests, it was decided that the use of a series of austenite-liquid diffusion couples would provide the most reliable results. This paper describes the method and its results and also includes a complete iron-carbon temperature-composition diagram based on what are considered to be the best available data. EXPERTMENTAL METHOD The diffusion couple used for this investigation consisted of a small cylindrical pellet of austenite held in contact, at a specified temperature, with a melt saturated with austenite. The composition of the cylindrical austenite pellet was chosen to be approximately 0.1 wt pct C less than the estimated

Jan 1, 1962

Discussion of the paper of John H. Hall, presented at the New York. Meeting, October, 1913, and printed in Bulletin No. 79, July, 1913, pp. 1247 to 1256. WILLIAM 'R. WEBSTER, Philadelphia, Pa.:-I would like to call ,attention to the fact that the results of the ordinary tension and bend tests do not always give us the information we want even if we figure out the amount of work done. You want a bending test of sufficient width and full thickness. In the case of eyebars, for instance, I have had experience with a 10- by 1-in. eyebar which gave perfectly good results in a full-size test of the finished bar. The 10- by 1.5-in. and 10- by 1.75-in. eyebars from the same heats-of steel were absolutely worthless in full-size tests. The narrow bending tests from all these bars gave good results. Bat after going into the matter fully, we found that if pieces about 3 in. wide and full thickness were used for the. cold bending tests, the heavier material would not stand this test, but failed. That is, in order to check the quality of the rolled bar you should have a wide piece of full thickness for cold bending, as the narrow pieces give misleading results. J. E. JOHNSON, JR., New York, N. Y. :-I would like to ask if there have been any tests made to compare the results of Charpy tests with the true dynamic test similar .to the Wohler test, except that the piece is subjected to a tensile or compressive stress and to alternating stresses in addition, at the same time. This seems to me to approach more nearly than any other test to the conditions of actual service. where the piece is under a fixed initial stress plus a highly variable and often alternating stress. Some tests were made on this plan in England within a year or two. The test piece was Subjected to either a tensile or compressive stress of known amount and simultaneously to alternating stresses in addition. Such a. test as this gives information which we cannot get by a tensile test or even from the tensile strength multiplied by an. elongation. Such tests, however, are exceedingly tedious and require long periods of time in order to obtain valuable results. If material could be subjected to these dynamic tests and the same material to the. Charpy shock test, and if some reasonable qualitative relation could be established between the results of the two tests, then we could assume that the shock test, which is so simple and easy to make, was a measurably accurate test of the dynamic qualities of the material. At present it does not seem

Jan 12, 1913

By G. D. Monk, W. C. Krumbein

The relation between permeability and the size parameters of unconsolidated sand is approached by considering sands as logarithmic frequency distributions having the basic parameters mean size and standard deviation. Sieve separates were mixed in accordance with the normal logarithmic probability law, so that the mean and standard deviation could be varied at will. Experiments were conducted in which one parameter was kept fixed and the other varied; in this manner the dependence of permeability on the individual parameters was evaluated. It was found that permeability can he expressed as the product of a power function of the mean size and an exponential function of the standard deviation. Earlier studies of the effect of size of particles on the permeability of uncon-solidated sand have shown that the permeability varies with the square of some average diameter. This was first pointed out by Hazenl in 1892 and verified by Slichter2 in 1898. Hazen's mean size was defined as the 10 percentile of the cumulative curve (i.e., size that is smaller than 90 pel cent of the distribution and larger than 10 per cent). Slichter's effective size, on the other hand, was found by Wilsey3,4 to agree with the 31 percentile. Fair and Hatch6 found that the geometric mean size of sieve separates yielded the same power function; Hulbert and Feben6 found that the permeability of sieve separates varied as the 1.89 power of the median diameter (i.e., the size associated with the 50 percentile of the cumulative curve). Relatively few studies included the effect of the "sorting" of the sediment on the permeability. It was recognized that the nature of the size distribution, in terms of the spread of the particles about the mean, affects the permeability, but no systematic investigations of this effect are known to the writers. Cloud7 demonstrated that the effect of the grain-size distribution on permeability is definitely measurable. In the present paper the authors investigate this relation analytically, and show that the effects of the size parameters on permeability may be predicted for at least a restricted set of conditions. Properties OF Sediments Recent investigations have shown that essentially all the geologically important characteristics of sediments may be expressed in terms of six measurable quanti-tities possessed by each clastic sedimentary particle. These attributes are: (I) size, (2) shape (sphericity), (3) roundness (angularity) , (4) mineralogical composition (density), (5) surface texture, (6) orientation. Each of these characteristics may be defined in several manners. Size may be expressed in terms of sieve mesh, settling velocity, volume, etc. Sphericity is a shape concept introduced by Wadell;8 it is essentially a measure of the ratio of the surface area of an equivalent sphere to the surface area of the particle. The same

Jan 1, 1943

By G. D. Monk, W. C. Krumbein

The relation between permeability and the size parameters of unconsolidated sand is approached by considering sands as logarithmic frequency distributions having the basic parameters mean size and standard deviation. Sieve separates were mixed in accordance with the normal logarithmic probability law, so that the mean and standard deviation could be varied at will. Experiments were conducted in which one parameter was kept fixed and the other varied; in this manner the dependence of permeability on the individual parameters was evaluated. It was found that permeability can he expressed as the product of a power function of the mean size and an exponential function of the standard deviation. Earlier studies of the effect of size of particles on the permeability of uncon-solidated sand have shown that the permeability varies with the square of some average diameter. This was first pointed out by Hazenl in 1892 and verified by Slichter2 in 1898. Hazen's mean size was defined as the 10 percentile of the cumulative curve (i.e., size that is smaller than 90 pel cent of the distribution and larger than 10 per cent). Slichter's effective size, on the other hand, was found by Wilsey3,4 to agree with the 31 percentile. Fair and Hatch6 found that the geometric mean size of sieve separates yielded the same power function; Hulbert and Feben6 found that the permeability of sieve separates varied as the 1.89 power of the median diameter (i.e., the size associated with the 50 percentile of the cumulative curve). Relatively few studies included the effect of the "sorting" of the sediment on the permeability. It was recognized that the nature of the size distribution, in terms of the spread of the particles about the mean, affects the permeability, but no systematic investigations of this effect are known to the writers. Cloud7 demonstrated that the effect of the grain-size distribution on permeability is definitely measurable. In the present paper the authors investigate this relation analytically, and show that the effects of the size parameters on permeability may be predicted for at least a restricted set of conditions. Properties OF Sediments Recent investigations have shown that essentially all the geologically important characteristics of sediments may be expressed in terms of six measurable quanti-tities possessed by each clastic sedimentary particle. These attributes are: (I) size, (2) shape (sphericity), (3) roundness (angularity) , (4) mineralogical composition (density), (5) surface texture, (6) orientation. Each of these characteristics may be defined in several manners. Size may be expressed in terms of sieve mesh, settling velocity, volume, etc. Sphericity is a shape concept introduced by Wadell;8 it is essentially a measure of the ratio of the surface area of an equivalent sphere to the surface area of the particle. The same

Jan 1, 1943

By E. J. Duggan

The mine and mill of the Climax Molybdenum Co. are at Climax, Colorado. Climax is on Fremont pass directly on the Continental Divide, at an elevation of 11,400 feet. Description of Ore The Climax ore-bearing rock is essentially an altered and highly silicified granite, fully half of the gangue being quartz. Molybdenite is the only mineral of economic consequence and most of it is intimately associated with quartz in the form of fine veinlets and stringers. Other minerals are molybdite, pyrite, and chal-copyrite. While the molybdite may be readily extracted by hydrometallurgical methods, its content is too low to make such operations profitable. The pyrite content ranges from 2 to 5 per cent and that of the chalcopyrite from 0.03 to 0.05 per cent. There is not enough copper to make its recovery attractive and one of the metallurgical problems is the elimination of it and the pyrite from the product. On account of the close association of the molybdenite with the quartz and the necessity of eliminating the pyrite and chalcopyrite from the final product, fine grinding followed by flotation is the only feasible method of concentration. History Construction of the first milling unit was started in 1917 and it was operated during parts of 1918 and 1919. In the postwar years, there was almost no demand for the product and production was at a standstill until 1924. The Company's research campaign to develop the use of the metal began to show results in that year. From r926 to 1932 production ranged from 500 to 1200 tons per day. In 1931 an additional mill section was built and production was gradually increased until in 1934 and 1935 about 3000 to 4000 tons was milled per day. This tonnage overtaxed the milling facilities, and as the demand for inolybdenum was growing constantly, additional milling equipment was needed. In 1936 and 1937 another crushing plant, six additional mill sections and the necessary auxiliary plants were constructed and brought into operation. This plant was designed to mill I0,000 tons per day, but it was not long before 12.500 tons was being treated during periods of peak demands. During the summer of 1941, to meet defense needs, the mill has been required to treat 15,500 tons per day. This has been accomplished with little plant expansion and at no loss in recovery, as will be described later. TO increase capacity still further, one more primary section is now being built. This will bring capacity to 18,000 tons per day, which can be stretched to 20,000 tons at a small sacrifice in recovery. Crushing There are two crushing plants: No. I, of 5000 tons capacity (flowsheet in Fig. I) and No. 2, of 15,000 tons capacity (Fig. a).

Jan 1, 1943

By E. J. Duggan

The mine and mill of the Climax Molybdenum Co. are at Climax, Colorado. Climax is on Fremont pass directly on the Continental Divide, at an elevation of 11,400 feet. Description of Ore The Climax ore-bearing rock is essentially an altered and highly silicified granite, fully half of the gangue being quartz. Molybdenite is the only mineral of economic consequence and most of it is intimately associated with quartz in the form of fine veinlets and stringers. Other minerals are molybdite, pyrite, and chal-copyrite. While the molybdite may be readily extracted by hydrometallurgical methods, its content is too low to make such operations profitable. The pyrite content ranges from 2 to 5 per cent and that of the chalcopyrite from 0.03 to 0.05 per cent. There is not enough copper to make its recovery attractive and one of the metallurgical problems is the elimination of it and the pyrite from the product. On account of the close association of the molybdenite with the quartz and the necessity of eliminating the pyrite and chalcopyrite from the final product, fine grinding followed by flotation is the only feasible method of concentration. History Construction of the first milling unit was started in 1917 and it was operated during parts of 1918 and 1919. In the postwar years, there was almost no demand for the product and production was at a standstill until 1924. The Company's research campaign to develop the use of the metal began to show results in that year. From r926 to 1932 production ranged from 500 to 1200 tons per day. In 1931 an additional mill section was built and production was gradually increased until in 1934 and 1935 about 3000 to 4000 tons was milled per day. This tonnage overtaxed the milling facilities, and as the demand for inolybdenum was growing constantly, additional milling equipment was needed. In 1936 and 1937 another crushing plant, six additional mill sections and the necessary auxiliary plants were constructed and brought into operation. This plant was designed to mill I0,000 tons per day, but it was not long before 12.500 tons was being treated during periods of peak demands. During the summer of 1941, to meet defense needs, the mill has been required to treat 15,500 tons per day. This has been accomplished with little plant expansion and at no loss in recovery, as will be described later. TO increase capacity still further, one more primary section is now being built. This will bring capacity to 18,000 tons per day, which can be stretched to 20,000 tons at a small sacrifice in recovery. Crushing There are two crushing plants: No. I, of 5000 tons capacity (flowsheet in Fig. I) and No. 2, of 15,000 tons capacity (Fig. a).

Jan 1, 1943

By M. R. Hatfield, F. J. Vosburgh

In a recent article, it was shown that in the blast furnaces in Germany that are lined with carbon blocks no cooling plates are used, and that shower cooling is employed on the hearth and bosh sections. While one of the authors was in Germany he was told that one furnace was being operated without even the shower cooling on the bosh section, though the hearth section was shower-cooled. In discussion of this interesting situation with a number of blast-furnace operators in this country, it was made clearly and promptly evident that shower cooling was very unpopular, probably because of its messiness and its ineffectiveness. Both of the causes for the dislike of shower coolings are reasonable ones. Shower cooling can be and frequently is messy, but the present cooling of blast furnaces leaves much to be desired on that score. Shower cooling is ineffective as compared with plate cooling, so far as its usefulness in keeping the bricks cool enough not to melt or fall to pieces is concerned. However, the introduction of carbon linings changes the situation. No one is concerned with keeping a carbon lining cool, for no temperature in the blast furnace has any effect on carbon, which is just as stable at 3000°F. as it is at 70°F. The only concern is for the shell—to keep it cool enough for safety and comfort— and for that shower cooling is sufficient. Of course, with only the shell to cool, instead of the shell plus all the refractory material, much less water would be required, and the necessity for constant attention to the flow would be lessened, as the hundreds of inlets and outlets would be eliminated. Probably half of the water used in cooling a blast furnace is used for cooling the shaft and tuyeres and the remainder for the bosh and hearth sections. However, in view of the dislike of shower cooling in the United States, and particularly because at least one German blast furnace is operated with no cooling of the bosh section, thought was given to the possibility that a carbon-lined blast furnace might be operated without any cooling of the entire carbon-lined portion. For that reason a series of experiments was performed to determine what might be the temperature of the shell of a blast furnace protected by a carbon lining and operated under varying conditions up to a maximum inside temperature of 3000°F. Experimental Procedure A schematic diagram of the experimental setup is shown in Fig. I and a photograph of the entire assembly in Fig. 2. The heating element was a a tubc nominally 25/8 in. 0.d. by 2 in. i.d. by 30 in., used as a resistor. Power was furnished by a I5-kva. transformer operating

Jan 1, 1942

By M. R. Hatfield, F. J. Vosburgh

In a recent article, it was shown that in the blast furnaces in Germany that are lined with carbon blocks no cooling plates are used, and that shower cooling is employed on the hearth and bosh sections. While one of the authors was in Germany he was told that one furnace was being operated without even the shower cooling on the bosh section, though the hearth section was shower-cooled. In discussion of this interesting situation with a number of blast-furnace operators in this country, it was made clearly and promptly evident that shower cooling was very unpopular, probably because of its messiness and its ineffectiveness. Both of the causes for the dislike of shower coolings are reasonable ones. Shower cooling can be and frequently is messy, but the present cooling of blast furnaces leaves much to be desired on that score. Shower cooling is ineffective as compared with plate cooling, so far as its usefulness in keeping the bricks cool enough not to melt or fall to pieces is concerned. However, the introduction of carbon linings changes the situation. No one is concerned with keeping a carbon lining cool, for no temperature in the blast furnace has any effect on carbon, which is just as stable at 3000°F. as it is at 70°F. The only concern is for the shell—to keep it cool enough for safety and comfort— and for that shower cooling is sufficient. Of course, with only the shell to cool, instead of the shell plus all the refractory material, much less water would be required, and the necessity for constant attention to the flow would be lessened, as the hundreds of inlets and outlets would be eliminated. Probably half of the water used in cooling a blast furnace is used for cooling the shaft and tuyeres and the remainder for the bosh and hearth sections. However, in view of the dislike of shower cooling in the United States, and particularly because at least one German blast furnace is operated with no cooling of the bosh section, thought was given to the possibility that a carbon-lined blast furnace might be operated without any cooling of the entire carbon-lined portion. For that reason a series of experiments was performed to determine what might be the temperature of the shell of a blast furnace protected by a carbon lining and operated under varying conditions up to a maximum inside temperature of 3000°F. Experimental Procedure A schematic diagram of the experimental setup is shown in Fig. I and a photograph of the entire assembly in Fig. 2. The heating element was a a tubc nominally 25/8 in. 0.d. by 2 in. i.d. by 30 in., used as a resistor. Power was furnished by a I5-kva. transformer operating

Jan 1, 1942

By W. C. Ellis, M. E. Fine

In the iron-cobalt system there are several property-composition relationships of theoretical importance. The alloys are ferromagnetic exhibiting a maximum saturation at approximately 33 at. pct cobalt;' the interatomic distances at room temperature show large positive deviations from Vegard's rule;2 and in the region of 50 at. pct cobalt there is an order-disorder transition2 which has a large effect on other properties. The thermal expansion data for the system have been reported only from room temperature to 100 C and for this temperature range a minimum in coefticient in the rcgion of 50 at. pct cobalt is well established.3,4,6 This paper reports the expansion properties in the iron-cobalt system for temperatures from 30 to 850°C, shows the correlation with other physical properties, and proposes an explanation for the tcrrelation. Experimental Procedure The thermal expansivities of iron-cobalt alloys in 10 pct steps in composition were determined from 30 to about 850°C. The major series of alloys was prepared by induction melting from Armco iron and cobalt rondelles with the addition of about 0.6 wt pct manganese. This series was supplemented by three compositions: high purity electrolytic iron, high purity electrolytic cobalt, and an alloy of 52.1 wt pct cobalt prepared from the high purity electrolytic iron and electrolytic cobalt by vacuum-melting. The compositions of both series of alloys are given in Table I. The specimens for measurement were prepared from the cast ingots by first hot-swaging followed in most instances by cold-swaging to 0.180-in. diam rod. Some alloys in the region of 5c pct cobalt, because of inherent cold-brittleness, were swaged hot to the final diameter. The expansion specimens were approximately 2 1/2 in. long with flat-ground and polished ends. Before measurement they were annealed in hydrogen for I hr at 900°C. In the apparatus used for the thermal expansivity measurements (Fig I), a modification of that designed by Hidnert and Sweeney,? the differential expausion between the specimen and vitreous silica was measured by a dial micrometer reading to 0.001 mm. An invar fixture supported the dial gauge, and this fixture, in turn, was connected to a split invar collar which supported the outer silica tube. A pyrex "T" was placed over the outcr silica tube and was sealed to the invar collar by Apiezon Q sealing compound. A movable hollow vitreous silica rod which rested on top of the test specimen slid through a flexible rubber diaphragm cemented to the top of the pyrex "T." The specimen rested On a vitreous silica pedestal fused into the outer tube and was kept centered by a silica sleeve. A nonoxidizing atmosphere was obtained by admitting hydrogen into the

Jan 1, 1949

By E. J. Duggan

THE mine and mill of the Climax Molybdenum Co. are at Climax, Colorado. Climax is on Fremont pass directly on the Continental Divide, at an elevation of 11,400 feet. DESCRIPTION OF ORE The Climax ore-bearing rock is essentially an altered and highly silicified granite, fully half of the gangue being quartz. Molybdenite is the only mineral of economic consequence and most of it is intimately associated with quartz in the form of fine veinlets and stringers. Other minerals are molybdite, pyrite, and chalcopyrite. While the molybdite may be readily extracted by hydrometallurgical methods, its content is too low to make such operations profitable. The pyrite content ranges from 2 to 5 per cent and that of the chalcopyrite from 0.03 to 0.05 per cent. There is not enough copper to make its recovery attractive and one of the metallurgical problems is the elimination of it and the pyrite from the product. On account of the close association of the molybdenite with the quartz and the necessity of eliminating the pyrite and chalcopyrite from the final product, fine grinding followed by flotation is the only feasible method of concentration. HISTORY Construction of the first milling unit was started in 1017 and it was operated during parts of 1918 and 1910. In the postwar years, there was almost no demand for the product and production was at a standstill until 1024. The Company's research campaign to develop the use of the metal began to show results in that year. From 1926 to 1932 production ranged from 500 to 1200 tons per day. In 1931 an additional mill section was built and production was gradually increased until in 1934 and 1935 about 3000 to 4000 tons was milled per day. This tonnage overtaxed the milling facilities, and as the demand for molybdenum was growing constantly, additional milling equipment was needed. In 1936 and 1937 another crushing plant, six additional mill sections and the necessary auxiliary plants were constructed and brought into operation. This plant was designed to mill I0,000 tons per day, but it was not long before 12,500 tons was being treated during periods of peak demands. During the summer of 1941, to meet defense needs, the mill has been required to treat 15,500 tons per day. This has been accomplished with little plant expansion and at no loss in recovery, as will be described later. To increase capacity still further, one more primary section is now being built. This will bring capacity to 18,000 tons per day, which can be stretched to 20,000 tons at a small sacrifice in recovery. CRUSHING There are two crushing plants: No. I, of 5000 tons capacity (flowsheet in Fig. I) and No. 2, of 15,000 tons capacity (Fig. 2).

Jan 1, 1942

By J. Murray Riddell, George A. Morrison

This paper is a companion to the one by George A. Morrison on Mining a Deep Limestone Mine in Ohio.‡ Barberton is 8 miles west of Akron, Ohio, and 23 miles south of Cleveland. The underground mining of limestone at Bar-berton constitutes the world's deepest limestone mine. The stratigraphy is as follows: 0-20 ft. Loam, clay, sand and gravel. Water bearing. 2-40 ft. Fractured sandstone. Water bearing. 40-110 ft. Sandstone with interbedded shale, slightly fractured. Water bearing. 110-314 ft. Sandstone with interbedded shale, slightly fractured. Water carrying. 314-2197 ft. Shale with occasional seams of sandstone, which varies in thickness from a few inches to 4 feet. Dry. 2197-2247 ft. Limestone. Dry. 2247-2742 ft. Dolomitic limestone. Dry. 2742-2767 ft. Salt. Dry. 2767- Dolomitic limestone. Dry. All of the strata dip to the southeast, about 0.5 per cent from the horizontal. The top 110 ft. of the crust is water-bearing. The rock strata are naturally fractured to a depth of 314 ft., sufficient to allow the passage of water. In the shaft-sinking operations, a stra- turn of oil-bearing sandstone one foot thick was encountered at a depth of 520 ft., and flows of methane gas were pierced at depths of 1350 and 1952 feet. Specifications for the mine plant called for, in part, the sinking of two vertical shafts and a hoisting plant capable of producing at the rate of 300 tons per hour. No. I shaft is 550 ft. west of No. 2 shaft. Each shaft measures 8 by 17 ft. outside of steel. General features of the design (Fig. I) are: Principal set members, 6-in. H-section; connecting angles (studdles), ? by 4 by 4-in. angle irons; spacing of sets. 8 ft. centers; spacing of bearer sets, generally, 160 ft.; bearers, of 12-in. I-beams. Each bearing set featured a concrete ring about the periphery of the shaft, steel to rock, and 8 ft. in height; permanent guides, 6 by 10-in. long-leaf yellow pine, 85 per cent heart. The Shaft-sinking Operation The preliminary shaft-sinking work consisted of driving interlocked steel piling about the exterior of the shafts to depths of 35 and 32 ft., respectively, and of such horizontal dimensions as to ultimately permit the pouring of a concrete collar 2 ft. in horizontal thickness. Following the pouring of a shaft collar, a temporary wooden headframe for shaft-sinking purposes was erected. The head-frame, while ordinary, featured: (1) a storage pocket of 300 cu. ft, capacity with truck servicing facilities, and (2) pneu matically operated dump doors, which mere actuated by the hoistman, thus caring

Jan 1, 1946

SINCE I told you in the preceding chapter how the potter's art is followed in practice, now in this following one I wish to tell you how mortar* and bricks are made, and how and to what purpose they were discovered, although I know you will answer that you know it, inasmuch as it is an art known not only to skillful men but also to the unskilled ones by whom it is practiced, and that bricks and mortar were made and always will be made for the purpose of building. This I admit, but probably everyone does not know it as you do, and you perhaps, do not know its beginnings, although I remember having told you of them. Wishing to repeat it better now I shall begin with long ago, so that both you and I may be better satisfied. Therefore I tell you that you should know that all the arts that men practice in the world have been learned by them either through the process of reasoning from the principles of natural phenomena, from the actions of animals, by chance, or when forced either by some necessity or

Jan 1, 1942

By M. D. Hassiallis

The claim is made in a number of patents1'2'3'4 that some compounds of the class known as aryl sulphides have collector properties. One of these patents generalizes the claim to include all aryl sulphides, whose generic formula is R-S2-R' (where x = 1,2, . . . ), with the restriction that if the aromatic radicals R, R' contain substituent groups these groups may not contain nitrogen or oxygen. Moses, Hess, and Perkins cite as evidence for their claims the results of flotation tests on Anaconda and Miami copper ores using diphenyl sulphide, ditolyl disulphide and dinapthyl disul-phide as collectors. The use of alkyl sulphides as collectors has also been reported5 with the conclusion that the alkyl sulphides are better collectors than the corresponding aryl sulphides. The experimental work cited appears to confirm this contention. In order to test these claims with respect to diphenyl sulphide, a sample, purchased from the Eastman Kodak Co., was tested against Anaconda ore. The procedure followed. was that of Moses, Hess, and Perkins. A sample of ore weighing 500 • grams was placed in a laboratory ball mill. To this was added 220 grams of water, 0.06 grams of commercial diphenyl sulphide (1/4 lb. per ton of ore), and 0.8 grams of lime (3 lb. per ton of ore). The material was ground until 93 per cent passed a 65-mesh screen. This pulp was diluted to 16 per cent solids. A sample of the diluted pulp was placed in a Minerals Separation type of laboratory flotation cell. After a a-min. agitation period, pine oil was added and the froth collected for a period of 15 min. This test recovered 68 per cent of the copper, with a ratio of concentration of 6.8:I. The tailing assay was 0.3 per cent Cu. Moses, Hess and Perkins attained a recovery of 75 per cent, with a ratio concentration of I2:I. Although these results do not compare too well with those of Moses, Hess and Perkins, subsequent tests showed an improvement, as judged by vanning of the tails. It is concluded, therefore, that the patent results are confirmed. Contact-angle Tests In order to study the response of the various minerals, found in Anaconda ore, to commercial diphenyl sulphide, some contact-angle tests were made. Polished particles of bornite, chalcodte, chalco-pyrite, pyrite and quartz were conditioned for 15 min. in a suspension of diphenyl sulphide in water. The concentration of this suspension was 0.284 grams per liter, this being the concentration of this reagent in the ball mill. The conditioned particles were rinsed with water (not rubbed with filter paper or boiled linen) and then tested against an air bubble in the bubble machine, with the following results: born-

Jan 1, 1943

By M. D. Hassiallis

The claim is made in a number of patents1'2'3'4 that some compounds of the class known as aryl sulphides have collector properties. One of these patents generalizes the claim to include all aryl sulphides, whose generic formula is R-S2-R' (where x = 1,2, . . . ), with the restriction that if the aromatic radicals R, R' contain substituent groups these groups may not contain nitrogen or oxygen. Moses, Hess, and Perkins cite as evidence for their claims the results of flotation tests on Anaconda and Miami copper ores using diphenyl sulphide, ditolyl disulphide and dinapthyl disul-phide as collectors. The use of alkyl sulphides as collectors has also been reported5 with the conclusion that the alkyl sulphides are better collectors than the corresponding aryl sulphides. The experimental work cited appears to confirm this contention. In order to test these claims with respect to diphenyl sulphide, a sample, purchased from the Eastman Kodak Co., was tested against Anaconda ore. The procedure followed. was that of Moses, Hess, and Perkins. A sample of ore weighing 500 • grams was placed in a laboratory ball mill. To this was added 220 grams of water, 0.06 grams of commercial diphenyl sulphide (1/4 lb. per ton of ore), and 0.8 grams of lime (3 lb. per ton of ore). The material was ground until 93 per cent passed a 65-mesh screen. This pulp was diluted to 16 per cent solids. A sample of the diluted pulp was placed in a Minerals Separation type of laboratory flotation cell. After a a-min. agitation period, pine oil was added and the froth collected for a period of 15 min. This test recovered 68 per cent of the copper, with a ratio of concentration of 6.8:I. The tailing assay was 0.3 per cent Cu. Moses, Hess and Perkins attained a recovery of 75 per cent, with a ratio concentration of I2:I. Although these results do not compare too well with those of Moses, Hess and Perkins, subsequent tests showed an improvement, as judged by vanning of the tails. It is concluded, therefore, that the patent results are confirmed. Contact-angle Tests In order to study the response of the various minerals, found in Anaconda ore, to commercial diphenyl sulphide, some contact-angle tests were made. Polished particles of bornite, chalcodte, chalco-pyrite, pyrite and quartz were conditioned for 15 min. in a suspension of diphenyl sulphide in water. The concentration of this suspension was 0.284 grams per liter, this being the concentration of this reagent in the ball mill. The conditioned particles were rinsed with water (not rubbed with filter paper or boiled linen) and then tested against an air bubble in the bubble machine, with the following results: born-

Jan 1, 1943

By Arthur F. Taggart, Nathaniel Arbiter

The fact that the floatability of minerals with fatty-acid collectors changes as the pH of a pulp varies was utilized in the early days of flotation, when sulphuric acid was used with oleic acid to float sphalerite and galena. from gangues which themselves float with fatty acids in alkaline pulps. Gaudin1 showed that this difference in floatability is a regular function of the extent of the change in pH. The present paper offers an explanation of the phenomenon, and on the basis thereof sets up recommendations for control of soap-flotation operations. Experimental Parallelism between floatability of a mineral in a given environment and its contact angle in that environment is so well established,2 and the contact angle is so readily and rapidly measurable, that contact angles have been used throughout the experimental work to indicate relative floatability. Experiments comprised contact-angle measurements on a number of representative minerals and metals, and a variety of subsidiary tests designed to check and to amplify the contact-angle indications. Contact-angle measurements were made by the method described in detail by del Giudice.3 Sequence of procedure for determination of the points of Fig. I was: I. Polish specimen. Most specimens yielded zero contact angle after polishing; a few showed a slight "cling." Cling is characteristic of specimens that pit on polishing; it is due to a residue of organic contamination, originally on the particle surface, which persists in the pits. The cling did not change total contact angle after conditioning, and is not, therefore, additive in the upper part of the curves of Fig. I. It may have broadened the bases of the curves for the affected minerals slightly. 2. The specimen was next conditioned in soap solution for 5 minutes. 3. The conditioned particle was transferred, under conditions that precluded surface drying, to an aqueous solution of the pH desired and contact angle determined. 4. The particle was thereupon transferred, again without surface drying, to water. The confirmatory tests will be described at the places pertinent in the argument. Discussion of Results Gaudin and Vincent4 have shown that contact angles with heptoic acid as a collector decrease for a given specimen when the concentration of collector present falls below a certain value. A similar reduction in angle occurs with collector-conditioned particles that are visibly slime-coated, and varies roughly with the extent of coating. Since in the last case the reduction in angle is certainly due to reduction in the proportion of total conditioned mineral surface presented to the bubble, the authors believe that the same condition prevails in the first case cited, and that similar reduction in angle and floatability will occur whenever starvation quantities of collector are present, whether by design or by reason of excessive consumption.

Jan 1, 1943

By Nathaniel Arbiter, Arthur F. Taggart

The fact that the floatability of minerals with fatty-acid collectors changes as the pH of a pulp varies was utilized in the early days of flotation, when sulphuric acid was used with oleic acid to float sphalerite and galena. from gangues which themselves float with fatty acids in alkaline pulps. Gaudin1 showed that this difference in floatability is a regular function of the extent of the change in pH. The present paper offers an explanation of the phenomenon, and on the basis thereof sets up recommendations for control of soap-flotation operations. Experimental Parallelism between floatability of a mineral in a given environment and its contact angle in that environment is so well established,2 and the contact angle is so readily and rapidly measurable, that contact angles have been used throughout the experimental work to indicate relative floatability. Experiments comprised contact-angle measurements on a number of representative minerals and metals, and a variety of subsidiary tests designed to check and to amplify the contact-angle indications. Contact-angle measurements were made by the method described in detail by del Giudice.3 Sequence of procedure for determination of the points of Fig. I was: I. Polish specimen. Most specimens yielded zero contact angle after polishing; a few showed a slight "cling." Cling is characteristic of specimens that pit on polishing; it is due to a residue of organic contamination, originally on the particle surface, which persists in the pits. The cling did not change total contact angle after conditioning, and is not, therefore, additive in the upper part of the curves of Fig. I. It may have broadened the bases of the curves for the affected minerals slightly. 2. The specimen was next conditioned in soap solution for 5 minutes. 3. The conditioned particle was transferred, under conditions that precluded surface drying, to an aqueous solution of the pH desired and contact angle determined. 4. The particle was thereupon transferred, again without surface drying, to water. The confirmatory tests will be described at the places pertinent in the argument. Discussion of Results Gaudin and Vincent4 have shown that contact angles with heptoic acid as a collector decrease for a given specimen when the concentration of collector present falls below a certain value. A similar reduction in angle occurs with collector-conditioned particles that are visibly slime-coated, and varies roughly with the extent of coating. Since in the last case the reduction in angle is certainly due to reduction in the proportion of total conditioned mineral surface presented to the bubble, the authors believe that the same condition prevails in the first case cited, and that similar reduction in angle and floatability will occur whenever starvation quantities of collector are present, whether by design or by reason of excessive consumption.

Jan 1, 1943

By Harmon D. Nine

DISCONTINUITIES in the strain vs cycles to failure (S-N) fatigue curves have been reported for polycrystalline materials by Porter and Levy for copper,&apos; by Benham and Ford for mild steel,&apos; and by Williams and Stevens for 18/5 stainless steel.3 However, the considerable scatter of the points for polycrystalline materials have made a statistical analysis of the data necessary to confirm the discontinuities. By using oriented single crystals of high-purity material and low grown-in dislocation content, the reproducibility has been improved to a degree which makes statistical analysis unnecessary and clearly shows discontinuities in the S-N curves. A recent publication4 reports an abrupt change of slope in the S-N curve for ( 100) axially oriented copper single crystals fatigued in torsion. The reported discontinuities in the S-N curve, along with a different mode of failure in the two branches of the curve, have been interpreted as being due to two different amplitude-dependent mechanisms. Further work on copper single crystals of (111) axial orientation has now been completed which supports the existence of an amplitude-dependent change in the mechanism of fatigue. In the present study torsional-fatigue experiments were performed at room temperature in air on (111) axially oriented single crystals. The crystals were grown and prepared as reported in Ref. 4. Two different methods of growing the crystals also discussed in Ref. 4 produced crystals of two different perfections: Type I with dislocation density of >l06 per sq cm and Type I1 with dislocation density of <l05 per sq cm. In accordance with the accepted hypothesis that crystal flaws are primarily responsible for the scatter of fatigue lifetimes, particularly at low amplitudes, the values for the three lowest amplitudes for Type I crystal are believed to be uncertain. They are marked in braces in Fig. 1. On the other hand, at amplitudes above a surface shear strain (SSS) of *0.003, the data for both types of crystals are in agreement. Most remarkably the S-N curve for torsional fatigue of (111)-oriented single crystals is composed of three segments separated by rather large discontinuities, Fig. 1. Metallographic and X-ray measurements indicate that the lower branch corresponds to the low-amplitude (F) region of the (100) copper single-crystal results as discussed in Ref. 4, and the two upper branches correspond to the high-amplitude (H) region. The lower discontinuity in the (111) S-N curve and metallographic evidence give further support to the hypothesis that different mechanisms of failure operate for high and low strain amplitudes. Reference to the resolved shear stress diagram, Fig. 2, shows that the highest stressed systems in

Jan 1, 1965

By Dr. Egleston

While I thoroughly appreciate the United States testing-machine at the Watertown Arsenal, and regard it as the most accurate testing-machine that has yet been built, I wish that I could say that it is complete in all respects. I not only fully appreciate it, but I have given up advising thesending of material to be tested anywhere else. It is five or six times more expensive to use this machine than any of the others, but the results which are obtained from it are, I think, perfectly reliable, and of such a character that the tests are all comparable with each other. It has proved, beyond a doubt, that the system of testing specimens of&apos; diminished area, and then calculating that the metal examined will be as many times stronger as its area is greater, is an absolutely vicious one. I am quite prepared to say, that, either from their limited size or faulty construction, most of

Jan 1, 1882