Search Documents

By Herman F. Kaiser, Charles S. Barrett, Robert F. Mehl

The copper-silver system presents several points of special interest in the study of segregate structures. The system is simple eutectic, with limited solid solutions terminal with the pure component metals. The extent of solid solubility decreases with decreasing temperature for both the copper-rich and the silver-rich alloys, thus offering a possibility for the formation of Widmanstätten figures and also a possibility for aging after quenching. In contrast to the structures studied previously the structures in this system are unique in their origin, for one terminal solid solution will precipitate the other, and vice versa. In most of the other systems for which crystallographic data on the precipitation (or transformation) process arc available, either intermetallic compounds or intermediate phases partake in the decomposition process; the absence of such phases thus distinguishes this system. The lattice structures of the two solid solutions are identical in type, differing in lattice spacing by approximately 10 per cent; because of this it seems difficult if not impossible to predict on the basis of present theory either the outward form of the precipitate or the lattice orientation relationships between matrix and precipitate. The eutectic temperature in the copper-silver system' is 779" C. At this temperature copper dissolves 4.3 atomic per cent (7.0 weight per cent) of silver in solid solution; this solid solubility decreases to zero at room temperature.² Silver at the eutectic temperature rctains 14.0

Jan 1, 1935

By Charles S. Barrett, Herman F. Kaiser, Robert F. Mehl

The copper-silver system presents several points of special interest in the study of segregate structures. The system is simple eutectic, with limited solid solutions terminal with the pure component metals. The extent of solid solubility decreases with decreasing temperature for both the copper-rich and the silver-rich alloys, thus offering a possibility for the formation of Widmanstätten figures and also a possibility for aging after quenching. In contrast to the structures studied previously the structures in this system are unique in their origin, for one terminal solid solution will precipitate the other, and vice versa. In most of the other systems for which crystallographic data on the precipitation (or transformation) process arc available, either intermetallic compounds or intermediate phases partake in the decomposition process; the absence of such phases thus distinguishes this system. The lattice structures of the two solid solutions are identical in type, differing in lattice spacing by approximately 10 per cent; because of this it seems difficult if not impossible to predict on the basis of present theory either the outward form of the precipitate or the lattice orientation relationships between matrix and precipitate. The eutectic temperature in the copper-silver system' is 779" C. At this temperature copper dissolves 4.3 atomic per cent (7.0 weight per cent) of silver in solid solution; this solid solubility decreases to zero at room temperature.² Silver at the eutectic temperature rctains 14.0

Jan 1, 1935

By H. O. Hofman

At the Lake Superior meeting, September, 1904, Messrs. A. Gibb and R. C. Philp presented a paper entitled " The Constitution of Mattes Produced in Copper-Smelting,"' in which they concluded that ferrous and cuprous sulphides formed the chemical compound, 5 Cu2S, FeS. They arrived at this inference from the observed fact that a matte containing Cu,S, 90.4, and FcS, 9.6 per cent. (or, in round figures, Cu2S, 90, and FeS, 10 per cent.), did not contain any metallic copper, while one with more than 10 per cent. of FeS readily dissolved copper, and with less than this amount retained copper in mechanical suspension. Although they determined the melting-points of five mattes containing from 32.6 to 80.1 per cent. of copper, they did not draw a freezing-point curve, as the necessary apparatus was not available. A microscopical examination of 11 polished samples gave them a grayish-black field of very uniform appearance, except that five of the specimens showed the presence of metallic copper. The object of the present investigation was to supplement the above paper by drawing the freezing-point curve of the ferrous sulphide-cuprous sulphide series, and to see how the constitution could be further revealed by microscopical work. The results obtained lead to conclusions very different from those of Gibb and Philp. While their paper bears the date 1904, it was published only in 1906.2 In the meantime, Bolles3 had presented his paper, " The Concentration of Gold and Silver in Iron-Bottoms." The raw material which formed the basis of the research was a matte containing Fe, 61.68, and Cu, 11.20

Jan 1, 1908

By Donald W. Gentry, John F. Abel

This paper presents some of the results of a rock mechanics instrumentation program designed for, and implemented at, longwall panel 4N at the York Canyon Mine near Raton, New Mexico. The objective of this particular instrumentation program was to determine the response of the rock mass to longwall mining of a thick coal seam utilizing shield-type supports. Measurements were made in the rock along the ground surface, above the coal seam, in the coal seam, and immediately below the coal seam. Longwall test panel 4N had a total developed length of 762 m (2500 ft) and a face width of 168 m (550 ft), Fig. 1. The seam mining height in the panel area was approximately 3 m (10 ft). The average depth of overburden above the panel is 107 m (350 ft) although it ranges from 73-134 m (240-440 ft). Roof support at the face was provided by 116 Hemscheidt 320 HSL shields. These shield-type supports weigh 11.4 metric tons each.

Jan 3, 1978

By J. W. Edington

THE Hopkinson bar has become a popular technique for the measurement of the mechanical properties of materials deformed at high strain rate. Maximum use of the equipment is made in the arrangement first used by Kolskyl in which a short compression specimen is sandwiched between two pressure bars and is loaded by a single pulse travelling through the system. The pressure bars are used both to apply the load to the specimen and as transducers to obtain continuous strain-time histories of three pulses, incident on, reflected, and transmitted by the specimen. The data measured by the pressure bars can be analyzed in terms of the stress/strain behavior of the specimen.2'3 However, one of the assumptions of the analysis of the observed pulses is that the total stress and total strain do not vary significantly from point to point within the specimen at any given instant during the deformation process. Although this assumption is generally justified for very short disc-like specimens2 the situation is uncertain for larger specimens. For example, at small plastic strains (-0.01) Hauser et al.2 have some evidence of small flucations in the total stress within the crystal during deformation, even in relatively short aluminum specimens. In addition, Karnes4 has shown that the plastic strain, and by inference strain rate, is different at each end of a compression specimen tested in a Hopkinson bar, although the length of the specimen was not specified. Recently, the mechanical properties and the dislocation substructure have been investigated in single crystals of columbium5 (length 0.25 in., diam 0.19 in.), and copper6 (length 0.5 in., diam 0.5 in.) deformed at high strain rates. As part of this research program the assumption that the plastic strain is constant throughout the specimen has been checked by measuring the total dislocation density as a function of position in the specimen. Compression specimens of the same orientations and dimensions were tested as described previously5,6 sing a split Hopkinson bar. Since any discontinuity in strain distribution is most likely to arise during the initial stages of deformation the investigation was performed on specimens deformed to plastic shear strains of 0.054 (copper) at a strain rate 1.2 x l03 sec-1, and 0.06 (columbium) at a strain rate 1.5 X l03 sec-1. The orientation of the single crystals is shown in Figs. 1 and 3. Thin foils were taken parallel to the most highly stressed slip plane, i.e., (111) in copper and (011) in columbium, using conventional disc techniques. The dislocation densities were measured using first order reflections with compensation for invisible dislocations.5'6 In the copper single crystals the discs were randomly distributed throughout the cross section of the specimen. However, the dislocation density obtained from each disc was plotted vs the disc positions relative to the ends of the specimen. The results for the copper specimens are shown in Fig. 1. Clearly the dislocation density is constant throughout the main portion of specimen within the experimental error. The error bars on the dislocation densities correspond to a shear strain variation of 0.015 on the basis of previous measurements% ± of the rate of increase of dislocation density with strain in copper single crystals of the same geometry. Thus within this experimental error the plastic strain can be concluded to be constant within the specimen and the assumptions used in the analysis of the stress/time curves are therefore reasonably valid. The higher measured dslocation density near the impact end and the lower dislocation density at the bar end of the copper specimen is in agreement with the results of Karnes4 who showed that this strain/time curve rose to a maximum more rapidly at the impact end compared with the bar end. Hauser et al.2 have also pointed out that at small plastic strains (-0.01) the strain at the impact end of the specimen may be greater than that at the bar end. Thin foils taken from different points within the columbium single crystals demonstrated that the dislocation density could vary significantly within the specimen, see Fig. 2. Large areas of some thin foils up to 30 µ sq contained very few dislocations, see Fig. 2(a). However, in other parts of the compression specimen dislocation configurations like those shown in Fig. 2(b) existed over large areas (-30 µ sq). As a result, when the average dislocation density in a thin foil is plotted as a function of the position of the thin foil relative to the ends of the specimen, considerable scatter is observed, see Fig. 3. In this material then, the local dislocation density, and consequently the

Jan 1, 1970

By K. Hodgson, N. C. Joughin

The detailed mechanism of rockbursts and other forms of damage due to rock failure in underground mining is as yet unknown. Studies of the energy changes which necessarily occur when an excavation is made underground seem to provide the best understanding of the phenomena leading to rock failure and damage (see Cook 1). It is common knowledge that the damage and rockburst hazard increases with depth and is greatest at remnants and in regions mined in an irregular manner. The rate at which energy is released as an excavation is enlarged provides an objective parameter to describe mining geometry in terms which are significant to studies of rock failure. In this paper, it is shown empirically that the rate of energy release per unit area increase in the size of an excavation is closely related to seismicity and incidence of damage in the mine. Consequently, it is suggested that the energy release rate is an important parameter in the design of underground mine layouts. Observations were made at two mines: the East Rand Proprietary Mines, Ltd. (E.R.P.M.), at a depth of about 9000 ft, and at Harmony Gold Mining Co., Ltd., at a depth of about 5000 ft. At both of these mines continuous recording seismic networks were in operation. (See Cook and Joughin.3) DESCRIPTION At E.R.P.M. the gold-bearing reef dips at approximately 35 degrees and is presently being mined at depths from 8000 ft to 11,000 ft below surface. The rock surrounding the excavation consists of a very homogeneous quartzite extending far into the hangingwall and footwall. The stoping width is approximately 40 in.

Jan 1, 1967

By R. W. Waterfill

MANY existing ore deposits of valuable metals have been worked out in their upper surface levels and the continued productivity of these mines is dependent on their extension to greater depths in the earth. The maximum depths at present reached are about 6000 to 8000 ft. below the surface, with no evidence of an impoverished ore vein. These mines are widely distributed; some of the best known are in South Africa, Brazil, India and in the western sections of the United States. Among the factors which increase the difficulty of working these mines at increasing depths are hoisting, rock pressure and temperature. The manner and effectiveness with which these problems are met will, no doubt, determine in a large measure the ultimate depths to which any mine can be profitably worked. The most critical of these three factors at present is the increase in temperature with depth. The high temperature and humidity in many of these mines at present is severely detrimental to the health of the workers and greatly hampers their efficiency. Some have almost reached a condition in which the human system cannot survive. The problems involved in the cooling and ventilation of mines have all been ably analyzed and presented in previous articles. For this reason, only a resume of conditions affecting the cooling and conditioning of deep and hot mines will be given in this paper before attention is directed to possible methods of improving atmospheric conditions in the working levels.

Jan 1, 1929

By Y. L. Yao

THE NaT1-type compound may be considered as the penetration of two diamond lattices in such a way that a superstructure of the bcc lattice is formed. Examples of the NaT1-type compound of lithium are LiZn, LiCd, LiA1, LiIn, and LiGa. Except for LiZn and LiCd, each molecule of these equiatomic compounds contains a total of four valence electrons. In LiZn and LiCd it was suspected (for example, see Ref. 1) that the fourth electron was withdrawn from the 18-shell of zinc or cadmium. An incomplete 18-shell would have to show strong paramagnetism. In 1955 Klemm and Fricke2 determined the magnetic susceptibility of LiZn, LiCd, LiA1, and LiIn (also NaTl and NaIn). The molar susceptibility of the outer electrons of LiZn and LiCd was found to be not strongly but weakly positive; that of LiAl and LiIn not negative but weakly positive. Thus they questioned the hypothesis about LiZn and LiCd in particular and the description of the NaT1-type structure in general. However, they did not determine the magnetic susceptibility of LiGa. This note is to report results for all five compounds of lithium. The starting materials are 99.9 pct pure lithium sticks containing less than 0.005 pct Na. 99.9 pct Zn, 99.9 pct Cd, 99.99 pct Al, 99.999 pct In, and 99.999 pct Ga. Weighed amounts of two components were wrapped in tantalum foil and placed in a graphite crucible. It was found that the tantalum sheath minimized the vaporization losses of lithium during melting. The sheath was easily stripped from the alloy rod and the tantalum in the alloy was barely detectable (less than 0.01 wt pct). The melting was performed in a resistance furnace under an argon atmosphere. Alloy specimens were annealed for 1 hr at 400°C in vacuum. The magnetic susceptibility at room temperature was determined by the Faraday Method, using the procedures previously described.' The results are shown in Table I. The interpolated values at 50 at. pct of Li and the average values at 48 to 52 at. pct of Li at 20°C determined by Klemm and Fricke2 are also shown. It is seen that the present value for LiZn and LiCd is slightly more positive but the present value for LiAl and LiIn is slightly less positive than their corresponding values. Also, it is noted there is an abrupt decrease of susceptibility of LiAl from 51.2 to 52.5 at. pct of Li. Klemm and Fricke2 found that the total susceptibility of LiZn, LiCd, LiA1, and LiIn is almost independent of temperature. slater4 gave a working expression for the diamagnetism of the atomic core as follows:

Jan 1, 1964

By G. C. Mudd, E. J. Myers

Within the last 15 years David Brown Gear Industries has manufactured approximately 200 large mill gears over 6m diam., 58 of them over 9 m and up to 12 m diam. The experience has not been without problems, due to a lack of clear understanding of the loads and stresses imposed on large gear wheels. American Gear Manufacturers Association (AGMA) practices suggest that a service factor be used for mill gears. But what is meant by "service factor"? The layman might be forgiven for believing that the term is synonymous with "safety factor," but this is certainly not true. The service factor is an aggregate of the following in some proportion: -An application factor, i.e., an allowance for the fact that systems do not run smoothly with uniform torque. -An ignorance factor covering the imperfections in the basic gear calculation. -Possibly a safety factor. In the following sections some of the ways in which the limits of applicability can be overstepped are discussed.

Jan 1, 1983

By D. A. Woodford

In a constant-load creep test, if the density of nlobile dislocations is assumed constant for strains exceeding that corvesponding to the minimum creep rate, it is shown that the creep rate may be approximated by the equation where E is the nominal strain, o0. is the initial stress, and a' the stress fov unit dislocation velocity. The constant C contains the mean density of mobile dislocations and n is a measure of the stress sensitivity of dislocation celocity. This equation is shoum to be applicable to published data on an alloy steel and on nickel. The degree of plastic instability and hence the creep ductility is dependent on the calue of n for these materials. When instability becomes gross and local macroscopic necking occurs, the assumptions are no longer valid. On the basis of this equation, and the strain-time relation derived from it, a method of predicting the creep behavior at different stresses is suggested. MOst analyses of creep data have been concerned with time-dependent transient creep or time-independ- ent secondary creep in constant-stress tests. The far more widely used constant-load test has been neglected in terms of a mechanistic approach. In general, since the strains involved are usually small, the same laws for transient creep may be applied to both types of tests. However, there is no steady-state creep in a constant-load test since the stress increases continuously. Any apparent steady state observed on a strain-time plot is either fortuitous or illusory, and is generally revealed as a continuously varying creep rate on a carefully constructed strain rate vs time plot.* Transient creep may be understood in terms of a simple differential equation representing the change in mobile dislocation density with time:' where p is the density of mobile dislocations. The first term on the right is related to first-order kinetics of dislocation multiDlication and the second to second-order kinetics of exhaustion. On the basis of this equation, several authors2-4 have found good agreement with experimental transient creep curves for a number of materials. When k1p = k2p2, a steady-state creep

Jan 1, 1968

By N. J. Olson, G. W. Toop

A series of equations previously derived for calculating ternary thermodynamic properties using binary data has been applied to the problem of predicting ternary phase diagrams and quaternary excess free energy. The methods are considered to be rigorous for regular ternary and quaternary systerns and empirical for nonregular systems. The equations have been used to predict ternary phase boundaries in the Pb-Sn-Zn system at 926°K and the Ag-Pd-Cu system at 1000ºK. Calculated quaternary excess free-energy values are presented for the Pb-Sn-Cd-Bi system at 773°K. A method for predicting the location of ternary phase boundaries would be a useful supplement to experimental measurements in ternary systems. This has been recognized with the considerable work that has been done to find models to predict or extend thermodynamic properties and phase diagrams in binary and ternary systems1-18 for which direct experimental measurements are limited. With the access to highspeed digital computers and mechanical plotting devices, it is currently rather easy to compare mathematical models with experimental data. The regular-solution model is consistent with systems which exhibit negative heats of mixing, positive heats of mixing, and miscibility gaps, and therefore it is applicable to simple phase diagrams. The purpose of this paper is to illustrate the use of regular-solution equations to predict, empirically, phase equilibria in some types of nonregular ternary systems. Corresponding equations for regular quaternary systems are given and used to calculate empirical quaternary excess free-energy data. METHOD FOR PREDICTING THE LOCATION OF TERNARY PHASE BOUNDARIES USING BINARY DATA Meijerin1,6 has used the regular-solution model to calculate common tangent points to ternary free energy of mixing surfaces and hence to determine phase boundaries in ternary systems involving miscibility gaps. He used the following equation to calculate ternary excess free energy of mixing values: stants characteristic of the binary solutions, and Ni is the mole fraction of component i. An alternate expression which gives for regular solutions as a function of binary values of along composition paths with constant N1/N2, N2lN3, and N1/N3 may also be derived:15 ternary r xs 1 ?c-*n.Ti*.U*. This expression for is more useful for the empirical calculation of ternary excess free-energy values for nonregular systems because actual binary AFXS data may be used in the expression rather than attempting to find suitable constants for Eq. [I]. The results of this feature of Eq. [2] are illustrated in Table I where calculated excess free-energy values for the Ni-Mn-Fe system at 1232°K are compared with experimental data of Smith, Paxton, and McCabe.19 Although regular-solution equations have been shown to give calculated thermodynamic quantities which agree quite well with experiment for single-phase nonregular ternary systems,14,15 care should be exercised in the use of the equations to predict thermo-dynamic properties of multiphase ternary systems in which strong compound formation is suspected. This precaution is consistent with the simple regular-solution model which for negative values of ai_j will indicate a tendency toward compound formation but even for very large negative values of ai-jwill not give multiphase binary or ternary systems involving a distinct stable compound. Hence, calculated ternary free-energy data using Eq. [2] might be expected to vary between being rigorous and poor, in the following order, for ternary systems which are: a) regular solutions, b) nonregular single-phase liquids in which random mixing is nearly realized, c) nonregular single-phase solids, d) nonregular multiphase systems exhibiting miscibility gaps, e) nonregular multiphase systems with binary compounds but no ternary compounds, f) nonregular multiphase systems with highly stable binary and ternary compounds. The calculated data will be expected to be least accurate for the last two cases. The general method adopted in this paper involves two-dimensional plots of ternary activity curves. The principle used is that tie lines indicating two-phase equilibria join conjugate phases a and B for example, for which a1(a) = a1(B), a2(a) = a2(B), and a3(a) = a3(B). Tie lines may be determined by plotting the ternary activities of two components along an isoactivity line for the third component and the unique points where the above equalities hold may be found graphically.

Jan 1, 1970

By Theron Wasson

The year 1942 in Michigan was devoted largely to the development of fields discovered in 1941 but was also characterized by a great increase in prospecting for new productive horizons below the Dundee limestone. Some new fields were discovered but as yet these have shown few signs of being of major importance. Michigan's total production for 1942, of 21,754,000 bbl. of oil, as reported by the U. S. Bureau of Mines, was second only to the record year of 1939 when 22,799,000 bbl. of oil were produced. All important fields were prorated throughout the year, and it is obvious that without proration a new all-time high would have been established for the state this year. From 1925 to the end of 1942, Michigan has produced annually the following amounts of oil: Year Barrels Source 1925 4,000 1926 94,000 1927 435,000 1928 592,000 1929 4,641,000 1929 Michigan Geological Survey 1930 3,928,000 3,785,000 1932 6,925,000 1933 7,942,000 1934 0,603,000 1935 15,776,000 U.S. Bur. Mines, 1937 1936 11,928,000 U.S. Bur. Mines, 1938 1937 16,628,000 U.S. Bur. Mines, 1939 1938 19,211,000 U.S. Bur. Mines, 1938 1939 22,799,000 1940 19,764,000 1941 16,361,000 1942 21,754,000 Total 183,170,000 This tabulation shows the steady growth of the industry in Michigan since the first discovery of oil in 1925. Maes A map of the oil and gas fields of Michigan in 1941, published in the report for 1942, shows the main producing areas and should be referred to if information in regard to their location is desired.* The main producing zones were shown in the columnar section in the same publication. Development in Fields Reed City Field.—During 1942 the Reed City field, which ended 1941 with 112 producing oil wells, added 70 new producers to bring the total at the end of the year to 182 wells and 4700 proven acres. A south extension of the field developed during the year was in large part responsible for the increase. Approximately 9,000,000 bbl. of oil was produced from the field during the year, bringing the total accumulated production to the end of the year to roughly 11,750,000 barrels. Headquarters Field.—The Headquarters field, which started the year with ro producing oil wells, ended the year with 41 wells aid 1240 proven acres. Approximately 2,300,000 bbl. of oil was produced in 1942. Kawkawlin Field.—Although not a 1941 discovery, the Kawkawlin field has been actively developed on the 40-acre spacing plan during the last year, 42 producers having been completed, bringing the total number of wells at the end of the year to 77. Nearly 500,000 bbl. of oil was produced during the year.

Jan 1, 1943

By Theron Wasson

The year 1942 in Michigan was devoted largely to the development of fields discovered in 1941 but was also characterized by a great increase in prospecting for new productive horizons below the Dundee limestone. Some new fields were discovered but as yet these have shown few signs of being of major importance. Michigan's total production for 1942, of 21,754,000 bbl. of oil, as reported by the U. S. Bureau of Mines, was second only to the record year of 1939 when 22,799,000 bbl. of oil were produced. All important fields were prorated throughout the year, and it is obvious that without proration a new all-time high would have been established for the state this year. From 1925 to the end of 1942, Michigan has produced annually the following amounts of oil: Year Barrels Source 1925 4,000 1926 94,000 1927 435,000 1928 592,000 1929 4,641,000 1929 Michigan Geological Survey 1930 3,928,000 3,785,000 1932 6,925,000 1933 7,942,000 1934 0,603,000 1935 15,776,000 U.S. Bur. Mines, 1937 1936 11,928,000 U.S. Bur. Mines, 1938 1937 16,628,000 U.S. Bur. Mines, 1939 1938 19,211,000 U.S. Bur. Mines, 1938 1939 22,799,000 1940 19,764,000 1941 16,361,000 1942 21,754,000 Total 183,170,000 This tabulation shows the steady growth of the industry in Michigan since the first discovery of oil in 1925. Maes A map of the oil and gas fields of Michigan in 1941, published in the report for 1942, shows the main producing areas and should be referred to if information in regard to their location is desired.* The main producing zones were shown in the columnar section in the same publication. Development in Fields Reed City Field.—During 1942 the Reed City field, which ended 1941 with 112 producing oil wells, added 70 new producers to bring the total at the end of the year to 182 wells and 4700 proven acres. A south extension of the field developed during the year was in large part responsible for the increase. Approximately 9,000,000 bbl. of oil was produced from the field during the year, bringing the total accumulated production to the end of the year to roughly 11,750,000 barrels. Headquarters Field.—The Headquarters field, which started the year with ro producing oil wells, ended the year with 41 wells aid 1240 proven acres. Approximately 2,300,000 bbl. of oil was produced in 1942. Kawkawlin Field.—Although not a 1941 discovery, the Kawkawlin field has been actively developed on the 40-acre spacing plan during the last year, 42 producers having been completed, bringing the total number of wells at the end of the year to 77. Nearly 500,000 bbl. of oil was produced during the year.

Jan 1, 1943

By Charles Legrand

The power plant of the Burro Mountain Copper Co. is located near Tyrone, N. M., at 5,950 ft. elevation. It is interesting because it uses the largest stationary Diesel engines in the United States. The general layout of the plant is shown in Figs. 1 and 2. The building is of steel-frame construction with hollow-tile walls and corrugated-iron roof; the floor is concrete and all windows have steel frames, making a fireproof building. The building is made to accommodate one more electric generator unit which is being installed; also two 4,000-cu. ft. air compressors direct-connected to three-cylinder engines with the same size cylinders as the electric units. The power plant consists of two 815-kva., 60-cycle, three-phase, 6,600-volt, 180-r.p.m. generators, direct-connected to five-cylinder, two-cycle Diesel engines; the necessary circulating pumps for cooling water, cooling towers and oil storage tanks. A portion of the power is used in the same building as the generating units to run one of two 200-kw. rotary converters delivering 260-volt direct current, and a 2,500-cu. ft. air compressor, delivering air at 95 lb. pressure, direct-connected to a 400-hp., 6,600-volt, three-phase synchronous motor. The remainder of the power is used to run a 1,500-ton concentrating mill 3 ½ miles from the power house, various hoists, pumps and motors about the mines and the lighting and water-works of the town of Tyrone. The direct current is used for electric traction in the mine, also to run hoists and motors that were installed before the new power plant was built. Due to the large hoists that take starting peaks of 250 kw. and the 10-ton electric locomotive that takes at times 150 kw., the load is extremely variable, as shown in. Fig. 3.

Jan 9, 1916

By M. Albertson

At Cobalt, Ontario, Canada, a lake was drained to facilitate mining, by the Mining Corpn. of Canada, during the spring and early summer of 1915. Previous to pumping out the water, great quantities of sands and slimes from concentrating plants had been discharged into the lake and during and after the lake's drainage, its basin was a receptacle for tailing products. As the writer was at work along the shore line as the lake was being drained, he had a good opportunity to observe the changes that took place as the water was withdrawn. Some adjustments between the incoming sands and the mud in the lake had taken place before pumping was commenced. One of the most interesting results was the appearance of a small dome in a path the writer traversed twice a day for several months; he remembers distinctly the difficulty of crossing this. Cobalt Lake owed its existence to the gouging out of a rock basin by glaciation. The long axis of the basin closely follows the strike of a thrust fault of about 500 ft. (160 m.) vertical displacement. The lake was originally shaped somewhat as shown. The length was about 3000 ft. (914.4 m.), the width at the lower lobe was about 1000 ft., and the width at the narrows probably 400 to 500 ft. The original depth of water varied from 20 to 30 ft. (6.1 to 9.1 m.), near where the island later was formed, to 60 to 70 ft. (23.6 to 27.6 m.) in the widest part of the lower lobe. At the narrows, the depth was 30 to 40 ft. Above the bed rock was sand, with boulders near the bottom, and mud. During the building of the railroad in 1903, considerable filling was done along the right of way. With the commencement of mining operations, about 1905, waste rock and mill tailings were dumped into the lake. One of the mining companies operated a hydraulic giant to remove the glacial debris from several hundred acres of rock surface; much of the sand and clay from this operation was deposited in the lake. About 1,500,000 tons of mill tailings, composed of sands and slimes, were discharged into the lake's waters previous to 1915. Most of this material

Jan 1, 1921

By Alden Greninger

METALLURGISTS have long believed that martensite in steel forms as plates along the octahedral {111} planes of austenite. Much has been written about mechanisms whereby units of the austenite lattice are pictured as transforming to martensite by shearing movements initiated along the octahedral planes of austenite, supposedly resulting in plates of martensite lying parallel to these planes of shear. A critical inspection of two or three photomicrographs of quenched hypereutectoid steel led us to the conclusion that the orientation habit of martensite, at least in hypereutectoid austenite, could not possibly be octahedral. Inasmuch as recent studies30,31 of the martensite-type reaction in nonferrous alloy systems have established the irrational orientation habit as characteristic of this type of lattice transformation, the need for a thorough restudy of the crystallography of martensite formation in steel was evident. The present paper reports the results of such a study, extended to include both cementite and some of the products of constant-temperature decomposition of austenite. Also reported are a few of the results obtained from a microscopic and X-ray study of the austempering process in very high-carbon steel.

Jan 1, 1940

By J. E. Andersen, J. Halpern, C. S. Samis

In the presence of oxygen, galena is oxidized in an aqueous medium containing sodium hydroxide, in accordance with the following reaction: PbS + 2O2 + 3OH ? HPbO2 + SO4 = + H2O A novel method was devised for following this reaction which takes place in an autoclave under oxygen pressure, by measuring the concentration of HPbO2- in the solution with a cathode ray polarograph employing stationary platinum electrodes. Using this procedure a study was made of the kinetics of the reaction, in which the effect of a number of variables, including temperature, oxygen pressure, NaOH concentration, and agitation, on the rate, were determined. The results of this study are described and discussed, in terms of possible mechanisms for the reaction. IT is known that sulphide minerals can be oxidized in aqueous media in the presence of oxygen under pressure. Reactions of this type can be classified in two categories depending upon whether the products of oxidation are insoluble or soluble in the aqueous medium. An example of the first type of reaction is the oxidation of pyrite in alkaline solutions, giving rise to an insoluble iron oxide. The kinetics of this reaction have been investigated and its mechanism established.' It has been applied in the oxidation of iron sulphides present in refractory gold ores to improve the subsequent recovery of gold by cyanida-tion.' The second type of reaction finds application where it is desired to recover the metal by leaching during oxidation. In this case a medium is selected in which the oxidized mineral is soluble. For example, nickel, copper, and cobalt sulphide ores can be treated by oxidation in the presence of a solution of ammonia dissolving the nickel, copper, and cobalt as the metal ammine sulphate salts.:' A similar treatment has also been reported to apply to zinc sulphide ores.' It is known that lead sulphate is soluble in solutions of sodium hydroxide or ammonium acetate. It should therefore be possible to dissolve the lead from galena ores by aqueous oxidation with oxygen under pressure using either of these solutions. The applicability of the ammonium acetate treatment has been investigated and confirmed in a recent study.' The present paper describes the results of a similar study in which the kinetics of the oxidation of galena in sodium hydroxide solutions have been investigated. The object of this investigation was pri- marily to obtain information of a fundamental nature relating to the kinetics and mechanism of this reaction. The use of pulps of comminuted ore in a study of this type is undesirable because of the difficulty in controlling and measuring the surface area. The measurements were therefore made using galena crystals of measured surface area and in this way absolute reaction rates were obtained. The reaction was found to proceed as follows: PbS + 2O2 + 3OH ? HPbO2 + SO4 + H2O [I] The products are sodium plumbite and sodium sulphate salts which dissolve in the aqueous solution. The reaction studies were carried out in an autoclave in which a desired pressure of oxygen was maintained. The reaction was followed by measuring the concentration of lead in the solution with a cathode ray polarograph. The results obtained in this investigation are presented and discussed in the present paper. Experimental Materials: The crystals of galena were obtained from Violamac Mines, Sandon, B. C. The following impurities were indicated by spectrographic analysis carried out by the Provincial Assay Office, Victoria, B. C.: Sn, 0.02 to 0.2 pct; Sb, 0.07 to 0.7; Zn, 0.01 to 0.1; Si, Fe, Mg, As, less than 0.05 pct; Ag, 126 oz per ton, the latter determined by standard fire-assaying procedure. After cutting a specimen measuring approximately 5x7x12 mm, the crystal surfaces were ground parallel to the 100 axes using No. 2 emery, washed with water, and the dimensions were measured with a micrometer. Oxygen gas was of commercial grade and supplied in cylinders by Canadian Liquid Air. Solutions were made up with chemicals of chemically pure grade and distilled water. Equipment: Autoclave: The autoclave used in these studies was constructed of stainless steel and

Jan 1, 1954

GWILLIAM H. CLAMER* (Philadelphia, Pa.).-Sulphur is not so detrimental in its effect if oxygen is also present, so that in sulphur-carrying bronzes and brasses, it is advantageous to maintain a certain percentage of oxygen. As a matter of fact, it would be possible sometimes to correct difficulties by actually adding oxygen. If the cathodes were charged directly into an electric furnace in a neutral or reducing atmosphere, a very high grade of copper would result by a simple melting operation. This would very largely eliminate the loss occasioned by melting in a reverberatory furnace. In such a furnace a large amount of slag is produced during the oxidizing stage of refining. Notwithstanding the fact that melting in an electric furnace might be somewhat more expensive than melting in a fuel furnace, the ultimate result would be a saving and the production of a very high grade of copper.

Jan 1, 1919

By George B. Langford

The McIntyre mine is in the Pearl Lake section of the Porcupine gold area. The rocks are Keewatin lavas intruded by quartz porphyries and albitite dies of Algoman age. Gold-bearing quartz veins are found in the Keewatin rocks near the porphyry stocks. The whole area has been highly compressed by forces acting along a N. 20°W. line. These forces folded the Keewatin rocks before the intrusion of the Algoman rocks, and later schisted both the Keewatin and Algoman rocks. Vein fractures were developed after the folding but before the development of the schist by the compres-sive forces being locally broken up into couples. These couples were set up by the differential resistance to deformation of porphyries and basalts, and also by the competency of the dacites and incompetency of the tuffs and fragmental rocks. During the important period of vein formation, two zones were developed—an inner productive zone in which the quartz veins are ankerite-bearing and an outer barren zone in which the quartz veins are calcite-bearing. The vein solutions originated in the same magrna that supplied the albitite dikes. Introduction The McIntyre mine, in the Porcupine gold area of northern Ontario, has passed its twenty-sixth birthday and has been producing gold since early in 1912. During this time approximately ten million tons of ore has been mined and over three and a half million ounces of gold recovered. This amount of ore would be sufficient to fill 2300 standard railway freight trains, each of 100 cars, and the gold produced, although only equivalent to a cube 51/2 ft. to the side, would weigh approximately 100 tons, a load for three freight cars. Silver has been produced in the ratio of 1 oz. of silver to every 4.4 oz. of gold, so that the total silver recovery is in the neighborhood of 700,000 ounces. The early history of the mine, like that of many others, shows that for several years it fought an uphill struggle for existence. One of the important features in winning this fight was the early recognition of some of the geological conditions responsible for the ore deposits, and the application of this knowledge in the search for ore and in the acquiring of adjoining properties. As early as 1913—only two years after the mine was opened—a geological department was organiaed. It has functioned almost continuously since that date and has demonstrated the importance

Jan 1, 1941

By George B. Langford

The McIntyre mine is in the Pearl Lake section of the Porcupine gold area. The rocks are Keewatin lavas intruded by quartz porphyries and albitite dies of Algoman age. Gold-bearing quartz veins are found in the Keewatin rocks near the porphyry stocks. The whole area has been highly compressed by forces acting along a N. 20°W. line. These forces folded the Keewatin rocks before the intrusion of the Algoman rocks, and later schisted both the Keewatin and Algoman rocks. Vein fractures were developed after the folding but before the development of the schist by the compres-sive forces being locally broken up into couples. These couples were set up by the differential resistance to deformation of porphyries and basalts, and also by the competency of the dacites and incompetency of the tuffs and fragmental rocks. During the important period of vein formation, two zones were developed—an inner productive zone in which the quartz veins are ankerite-bearing and an outer barren zone in which the quartz veins are calcite-bearing. The vein solutions originated in the same magrna that supplied the albitite dikes. Introduction The McIntyre mine, in the Porcupine gold area of northern Ontario, has passed its twenty-sixth birthday and has been producing gold since early in 1912. During this time approximately ten million tons of ore has been mined and over three and a half million ounces of gold recovered. This amount of ore would be sufficient to fill 2300 standard railway freight trains, each of 100 cars, and the gold produced, although only equivalent to a cube 51/2 ft. to the side, would weigh approximately 100 tons, a load for three freight cars. Silver has been produced in the ratio of 1 oz. of silver to every 4.4 oz. of gold, so that the total silver recovery is in the neighborhood of 700,000 ounces. The early history of the mine, like that of many others, shows that for several years it fought an uphill struggle for existence. One of the important features in winning this fight was the early recognition of some of the geological conditions responsible for the ore deposits, and the application of this knowledge in the search for ore and in the acquiring of adjoining properties. As early as 1913—only two years after the mine was opened—a geological department was organiaed. It has functioned almost continuously since that date and has demonstrated the importance

Jan 1, 1941