Search Documents

By R. S. Wagner, H. Brown

Criteria for nucleation with the aid of twin planes during crystal growth from the melt are discussed. It is shown experimentally that bismuth crystals can grow from a subercooled melt in a twinned bismdtic form. A mechanism of growth based on the presence of at least me twin plane is proposed. It is well known that faceted growth can be observed in crystals grown from the vapor phase, dilute solutions, or from the melt. Faceted growth, in which the crystal is bounded by its slowest growing faces, will occur if the growth rate is strongly orientation dependent. The addition of atom layers on a facet plane can only occur by two-dimensional surface nucleation or with the aid of an imperfection. Nucleation with the aid of dislocations was proposed by rank' and observed to be of particular importance in crystal growth from the vapor phase. Nucleation with the aid of two-dimensional imperfections, notably twin planes, was suggested by stranski2,3 and Frank.4 A twin plane, terminating at the growth interface, can form a reentrant step at which nucleation can occur at a much smaller super-saturation (or supercooling) than required for two-dimensional surface nucleation. Nucleation by a twin plane usually results in a fast growth rate along a crystallographic direction parallel to the twin plane. Such a nucleation mechanism, based on the presence of a twin plane, has been used by Dawson5 to explain the growth and morphology of sheet-like crystals of paraffin n-hectane. In recent years more evidence was found that nucleation by twin planes occurs frequently in crystal growth from the vapor phase and from dilute solutions, for example, in cadmium,' barium titanate,7 silver,8 silicon9 and gallium arsenide.10 In crystal growth from a supercooled melt, however, nucleation by twin planes has so far only been observed in materials with the diamond or zinc blende structure. Bennett and Longini11 were the first to recognize the important role a single twin plane plays in the growth of germanium dendrites. Subsequently, it was found that a prerequisite for continued propagation of germanium dendrites is the presence of two parallel twin planes which form a self-perpetuating system of nucleation sites.12 Sili- con and some III-V compounds such as InSb also grow dendritically by twin plane nucleation. It appears that the following criteria must be satisfied in order that nucleation with the aid of twin planes can occur: A) The growth form of the material must be faceted." B) The formation of twin boundaries, by a fault in layer sequence during growth, by plastic deformation, or by an accidental meeting of properly oriented crystals, must be possible. C) Twinning must form a reentrant step where the twin boundary terminates at the faceted growth interface. D) These three conditions are necessary, but in certain cases not sufficient for continued crystal growth with the aid of a twin plane. Depending on interface morphology, a combination of more twin planes is sometimes required to form a self-perpetuating system of nucleation sites. This investigation was carried out with the idea in mind that nucleation with the aid of twin planes is a more general phenomenon and should occur in those materials, grown from a supercooled melt, which satisfy the criteria outlined above. It has been found that crystals of high-purity bismuth grown from a supercooled melt can grow by the aid of a twin plane. In the first two sections the faceted growth form and the twinning elements of bismuth are discussed. In the last section prismatic crystals of bismuth, which appear to grow with the aid of a deformation twin are discussed.

Jan 1, 1962

By Philip W. Moen

It is with sincere regret that the members of the Institute will have heard of the death, on March 17th last, at Terre Haute, Ind., of Professor Charles 0. Thompson, A.M., Ph.D., President of the Rose Polytechnic Institute of that city, and for many years pre viously the head of the Worcester County (Mass.) Free Institute of Industrial Science, and in 1881 and 1882 one of the managers of this society. To us he was chiefly known by the excellent character of the work which he had performed, as a recognized leader among the technical educators of the country. He was a constant, and interested atten dant at our meetings, seeking to acquaint himself not less with all that was noteworthy in the practical attainments and developments of the branches of industry represented by our membership, than with such such facts as would be of service to him in shaping or guiding a wise course of instruction in the institutions of which he had charge. We shall not soon forget him, or the genial courtesy of his manner, or his ready words and thoughtful comments. Charles Oliver Thompson was born September 25th, 1836, at East Windsor Hill, Conn., where his father, Rev. William Thomp son, D.D., was professor in the Connecticut Theological Seminary, since removed to Hartford. The son was fitted for college under the late Paul A. Chadbourne, and entered Dartmouth College in 1854. He was graduated in 1858 with honors. In all the studies of his course he had maintained a high rank, but showed marked proficiency in chemistry and mechanical philosophy. In 1861 he received the degree of A.M., followed by that of Ph.D. from his own college in 1879, and from Williams in 1880. In September, 1858, the year of his graduation, he became principal of the Peacham Academy, Vt., remaining in that position until November of 1864, though during that period he devoted several months to practical work as a surveyor and civil engineer. Thus his experiences were developing the qualities which, later on, fitted him to carry out so successfully the plans of the thoughtful projectors of a new system of technical education, along a path before untrodden, but which the test of time and the indisputable proof of success have shown to be both wise and fruitful.

Jan 1, 1886

By W. O. Philbrook, H. W. Hosking, N. B. Melcher

Rates and patterns of gas flow in an experimental blast furnace were investigated by measurements, at three levels, of gas compo-sitions and temperatures and by direct determination of gas transit time by a new method employing mercury vapor as a tracer. Infer-ences were drawn about localized reaction zones and the mechanism of the onset of' channeling. LACK of precise knowledge of the nature of gas movement in the blast furnace has always been an impediment to better understanding of the blastfurnace process as a whole. The effects upon operation of various types of charge distribution are very largely brought about by the modifications to gas flow which they occasion. Intelligent evaluation of these effects demands a better understanding of the factors influencing gas flow and the ways in which the flow pattern is altered by conditions existing in the stock column. The same knowledge is required before a fundamental approach can be made to the problem of establishing optimum lines for new furnaces. An experimental furnace is operated at the Bureau of Mines Central Experiment Station, Pittsburgh, Pa. Advantage was taken of experimental operation to conduct an investigation to develop and evaluate methods of study which could be applied later to industrial furnaces. The gas composition and temperature determinations were made as a preliminary study so far as gas flow was concerned but yielded significant information relating to other processes occurring within the furnace. The direct measurement of gas transit times by the mercury-vapor method constituted the major object of the investigation. Development of the mercury-vapor method was carried out while the data on gas composition and temperature were being collected. A complete description of the principle and development of the mercury-vapor method is beyond the scope of this paper but is available elsewhere. The results obtained and some consideration of the method's effectiveness and its potential value in the study of industrial problems will be treated here. DESCRIPTION OF FURNACE The general lines of the experimental blast furnace are shown in Fig. 1. The hearth diameter was 3 ft at the beginning of the investigation, and this was later enlarged to 3 ft 9 in. and finally to 4 ft to increase capacity. Tuyere to stockline height is 21 ft 4 in. The bosh depth is 3 ft 4 in. over which it opens to a width of 5 ft, and this diameter is carried up for 2 ft in a cylindrical section. The inwall batter of 1/2 in. per ft. is considerably less than in larger installations This may have influenced the movement of gaseous and solid materials. The furnace is inside a laboratory building and is charged from outside by a skip and hoist. Feeding into the first of three bell chambers, the stock is distributed by rotating the upper bell, the other two being used to obtain an effective gas seal. Three water-cooled tuyeres, with a nozzle dia-

Jan 1, 1960

By E. S. Machlin, C. W. Chen

RECENTLY Chen and Machlin' proposed a mechanism for intercrystalline cracking in metals during high-temperature stressing. According to this mechanism the formation of voids at grain boundaries is primarily responsible for intercrystalline cracking. A model has been provided to demonstrate the initiation of submicroscopic cracks and voids at jogs of grain boundaries where grain boundary sliding is inhibited. Submicroscopic cracks can grow as a result of either further grain boundary sliding or localized tensile stress. In the former case, it is believed that grain boundary sliding produces more voids which link together to produce macroscopic cracks and which may lead to the eventual failure of the metal. Concurrently, Nield and Quarrell2 reported their interesting results obtained in a systematic investigation of intercrystalline cracking in two aluminum alloys under various creep conditions. Their observations are generally in agreement with the above mechanism, especially the conclusion that voids are formed as a direct consequence of grain boundary sliding. On the basis of the volume fraction occupied by voids, they could find no confirmation of vacancy condensation as the mechanism for void growth. Furthermore, an important feature of intercrystalline cracking has been likewise pointed out by them that the majority of cracks are not formed at grain corners. Nield and Quarrel1 meanwhile emphasized the importance of grain boundary migration by designating it as one of two main processes operative in the mechanism of crack formation during creep. The designation seems unnecessary because overemphasis of grain boundary migration only complicates the mechanism of void formation. There are two reasons which militate against the inclusion of grain boundary migration in the mechanism of void formation. In the first place, the formation of intercrystalline voids per se does not require grain boundary migration. Secondly, in addition to grain boundary migration, void formation may be minimized by any other process such as plastic deformation which is capable of relieving localized stresses around jogs. Chang and Grant3 have shown that intercrystalline cracking is prevented in aluminum by lattice bending in high stress regions. The influential role played by grain boundary migration in creep has also been realized in our studies. In several cases, voids did not appear at all in grain boundaries whenever grain boundary migration took place prominently during creep. The purpose of this paper is to discuss the effect of grain boundary migration on the formation of intercrystalline voids and other related rupture properties. Experimental evidence indicates that in an unstable grain structure void formation may be markedly modified by structural changes. The abnormally high ductility and the transcrystalline mode of fracture observed in copper at elevated temperatures reveals that effective grain boundary migration minimizes void formation. Grain boundary migration has long been known as a common high-temperature phenomenon in metals with the grain configuration in a nonequilibrium state. Its effect on ductility and mode of fracture has not been recognized until recently.4 Since the introduction of the term "Equicohesive Temperature," the conventional belief has been that below the equicohesive temperature the ductility of metals increases moderately with decreasing temperature until the ductile-to-brittle transition temperature of fracture is reached. In this temperature range, metals fracture in a ductile mode with a "cup-and-cone" fracture surface. Above the equicohesive temperature, ductility remains invariably low and decreases slightly with increasing temperature. The mode of fracture is strictly brittle and intercrystalline. Typical examples have been shown for a brass and copper in Fig. 1 and 9, respectively, in the paper by Greenwood, Miller, and Suiter.5 The observation in the upper temperature range that ductility of metals is low and insensitive to temperature may be explained in terms of void formation at grain boundaries. It is also in accordance with the findings of McLean6 and Fazen, Sherby, and Dorn7

Jan 1, 1961

By I. H. Silberberg, R. L. Reed, O. K. Kimbler

interfacial films have frequently been observed at interfaces between certain crude oils and water. Several investigators have postulated that the presence of these films should influence the efficiency of oil recovery in water drive or waterflood operations. They may also influence the stability of emulsions which are sometimes a problem in petroleum production, and may be a factor in the fonation of paraffin deposits in oil well tubing and flow lines. This paper presents a technique with which a modified Langmuir film balance may be used to study the compressibility and collapse pressure of these natural interfacial films. Experimental data are presented for several nude oil-water systems. Data developed are used to infer the phase state of the film as a function of such variables as rate of reduction of interfacial area, ionic composition of the subtrate and pH of the subtrate. A film of known physical characteristics is shown to have a sinnificant effect on oil recovery from an unconsolidated sand pack. Possible applications of these results to petroleum production are discussed. INTRODUCTION The use of water to displace petroleum from reservoir rocks is of major importance both as a primary and a secondary recovery process. As water invades the rock, oil is completely displaced from some pores and left as a discontinuous phase in other pores. The manner in which water moves from pore to pore is strongly influenced by capillary forces. In view of the complexity of reservoir fluid systems, there can be little doubt that complicated interactions take place at both the liquid-solid and oil-water interfaces. One of the more interesting, and least understood, of the phenomena which take place at the oil-water interface is the formation of interfacial films. These films are believed to result from the adsorption of high molecular weight polar molecules at the interface.l.2 Presence of such molecules may cause a striking alteration in interfacial tension. When the oil-water interfacial area of certain crudes is rapidly reduced, a thin region (film) about the interface assumes the appearance of a solid membrane, and striations, wrinkles and gross distortions may occur. If such a film is solid, it should greatly alter the interfacial tension normally assumed to exist between the oil and water phases. If the membrane is continuous, a solid phase would separate the oil and water. Interfacial films between crude oil and water were observed in 1949 by Bartell and Niederhausers who commented upon the apparent rigidity of the films and their possible importance in the petroleum industry. Morrell and Egloff4 had earlier attributed the extreme stability of emulsions of sea water in fuel oil to very stable asphaltic films. Numerous investigators have observed rigid films in the course of crude oil-water interfacial tension determinations by the pendent drop method. Several investigators5,6,2 have separated inter-facially active materials from crudes and attempted to characterize them chemically. Reisberg and Doscher,2 using Ventura crude, showed the interfacial tension against water (as measured by the pendent drop method) to be affected by aging, contraction and expansion of the interface, and the pH of the water. These investigators attributed the adhesion of oil to a water-wetted surface and the distortions of flow paths in glass capillaries to the presence of rigid films. Dodd7 has studied the interfacial viscosity of adsorbed films and found them to be non-Newtonian in behavior. Craighead and Harvey8 reported a series of displacements in tubes packed with 60 mesh glass beads. They interpreted the results as indicating an effect of stearic acid films on waterflood recovery and imply that natural films may produce similar results.

Jan 1, 1967

For the year ending February, 1920 PRESIDENT HORACE V. WINCHELL MINNEAPOLIS, MINN PAST PRESIDENTS PHILIP N. MOORE ST. Louis, Mo. SIDNEY J. JENNINGS NEW YORK, N. Y. FIRST VICE-PRESIDENT A. R. LEDOUX NEW YORK, N. Y. TREASURER GEORGE D. BARRON NEW YORK, N. Y. SECRETARY BRADLEY STOUGHTON NEW YORK, N. Y.

Jan 4, 1919

By R. M. Asimow

The magnetization curves for specimezs containing superparmagnetic particles are considered. It is shown that the curves may differ from a Langezlin function because of particle anisotropy, particle interactions , and the presence of a size distribution of particles. The various causes of particle anisotropy are considered, and magnetization curves for specimens with cubic and uniaxial anisotropy are presented. The magnetization curves depend on the In the particle-size below 100A it is quite difficult to obtain quantitative size and shape information on precipitate particles. All of the available techniques have their limitations; however, quantitative applications of superparmagnetism have not been developed as fully as possible due to a lack of analysis of the complete magnetization curve. With such an analysis it appears possible to obtain from a single magnetization curve of a specimen containing randomly oriented SPM (superparamagnetic) particles a quantitative volume distribution and a description of the particle shape.* sign of the anisotropy energy and in the case of a negative uniaxial anisotropy (prolate spheroids) the resulting curves may differ very considerbly from a Langevin function. A graphical technique is developed whereby it is possible to separate out the effects of the size distribution, the particle interaction, and the particle anisotropy. Thus it is possible to obtain quantitative values for both the particle shape and the size distribution. Langevin function2 I/Is = ctnh(HVIs/k T)-k T/HVIS [ 1 ] where I, is the saturation magnetization, V the particle volume, H the applied field, T the particle temperature, k the Boltzmann constant, and I the magnetization in the direction of the applied field. Such behavior is rarely if ever observed in actual systems. One explanation for this is that the SPM particles do possess a significant anisotropy and thus the magnetic energy associated with the particle depends on the direction of magnetization in a more complicated way than for the isotropic particle of Eq. [I]. In general the magnetic energy E of an isolated SPM particle embedded in a nonmagnetic matrix can be expressed as a sum of several contributions: E = Eh + Ed+Es+Ec [2] where Eh is the external field energy, Ed the energy resulting from the particle demagnetizing factor, E, the magnetostriction energy, and E, the crystalline anisotropy energy. In each term we consider only the part dependent on the orientation of the magnetization vector and the particle axes as the shape of the magnetization curve will be determined by these contributions. Following the same procedure used in deriving the Langevin function,

Jan 1, 1965

By R. Kossowsky

BRIDGMAN has listed five possible transitions in bismuth at 25°C which were observed as volume changes. He was unable however to detect the last three transitions by electrical-resistivity changes. Kennedy and LaMori have verified the pressures at the Bi 1-11 and Bi 11-111 transitions. They suggested however that the 125-kbar transition previously reported by Bundy3 actually corresponds to the 90,000 kg per sq cm transition observed by Bridgman.1 Jura4 reported a well-defined drop in resistivity at 92 kbar obtained by a four-lead method. The Bi 111-IV and Bi IV-V transitions have not been reported in any of the above-mentioned references.'-' Bundy3 observed a small dent in the low-temperature boundary of the Bi Vll region which is consistent with the presence of a 111-IV boundary. Zeitlin and Bray-man5 were the only ones to report small but well-defined drops in resistance of bismuth at 44.0 and 63.8 kbar, corresponding to Bridgman's 111-IV and IV-V transitions, respectively. High-purity (99.99 pct) 0.020-in.-diam 0.5-in.-long bismuth wire was used to calibrate the Uniram tetra-hedral high-pressure apparatus used in the present work. The bismuth phase changes at 25°C were correlated with changes in electrical resistance as a function of pressure. The output of a sensitive bridge constructed of carbon resistors and kept at a constant temperature of ±°C during the measurements was fed to the Y axis of a MoseleyX-Y recorder and the X axis was used for time scans. Specimens were pressurized using a hydraulic press with maximum capacity of 200,000 lb. Load was applied in increments of 2000 lb and held for about 3 min. The resistance was recorded at the end of this time period. Good contact was established below 20,000 lb. Typical recorder charts are reproduced in Figs. 1 and 2 which show that resistance fluctuations were practically nil during each time scan. Well-defined discontinuities in resistance were observed at 58,000 and 82,000 lb, Fig. 1. Two small but definite "blips" are noticed at 92,000 and 122,000 lb, Fig. 2. At 156,000 lb another drop is observed which

Jan 1, 1967

For the year ending February, 1920 PRESIDENT HORACE V. WINCHELL MINNEAPOLIS, MINN. PAST PRESIDENTS PHILIP N. MOORE ST. LOUIS, Mo. SIDNEY J. JENNINGS NEW YORK, N. Y. FIRST VICE-PRESIDENT A. R. LEDOUX NEW YORK, N. Y. TREASURER GEORGE D. BARRON. . . . ' NEW YORK, N. Y SECRETARY BRADLEY STOUGHTON NEW YORK, N. Y

Jan 6, 1919

For the year ending February, 1920 PRESIDENT HORACE V. WINCHELL MINNEAPOLIS, MINN. PAST PRESIDENTS PHILIP N. MOORE ST. Louis, Mo. SIDNEY J. JENNINGS NEW YORK, N. Y. FIRST VICE-PRESIDENT A. R. LEDOUX NEW YORK, N. Y. TREASURER GEORGE D. BARRON NEW YORK, N. Y SECRETARY BRADLEY STOUGHTON NEW YORK, N. Y.

Jan 12, 1919

By James Norman, E. W. Gieseke

SPODUMENE is a lithium-bearing pyroxene, and is an important source of lithium compounds. Because of its high alumina and lithia content. it might be a desirable constituent of glass batches. The use of spodumene in ceramics will undoubtedly increase, as it has been shown that a mixture of the proper proportions of this mineral with soda feldspar and potash feldspar has a much lower maturing temperature upon firing than has any one of the three components.1 The mineral spodumene seldom occurs as pure mineral, but ordinarily with feldspars, mica and quartz. All spodumene-bearing rocks tested contained these minerals as gangue. Small amounts of iron and manganese oxides also were present, usually as stains on the silicate grains. Mica associated with the spodumene carried a considerable amount of lithia. This was discovered in flotation tailings, which, although virtually free of spodumene grains when examined microscopically, showed 0.4 to 0.5 per cent Li20 on chemical analysis. The lithia content of micas picked from the North Carolina spodumene rock was variable. Some samples contained little lithia, others more than 3 per cent. In 1938, under the supervision of Oliver C. Ralston, [t] the Bureau of Mines, in cooperation with the Tennessee Mineral Products Corporation, undertook to study the beneficiation of North Carolina spodumene by froth flotation. The Bureau had previously published investigations on the beneficiation of spodumene.2, 3 The methods described in the second publication3 did not give good results with badly weathered spodumene rock, so that more thorough investigation of the subject was warranted. STUDY OF METHOD OF FLOTATION SEPARATION Most of the work on concentration of spodumene was done with rock from near King's Mountain, North Carolina. Rock from two

Jan 1, 1940

By George D. Dub

Owens Lake is at present a source of important nonmetallic minerals, sodium carbonate (soda ash, Na2CO3); sodium sesquicarbonate (trona, Na2CO3.NaHCO3.-2H2O) and borax, (Na2B4O7.10H2O). Owens Lake is a closed basin in the southern part of Inyo County, California, at the southern end of Owens Valley, east of the Sierra Nevada Mountains and west of the Coso and Inyo Mountains. Broadly considered, it is in the Great Basin area, but at no time was it a part of Lake Lahontan. Closed Basins Closed basins are phenomena of arid or semiarid regions where outflow is considerably less than inflow and where accordingly soluble salts concentrate in residual liquid. When inflowing waters originate in areas where the rocks are predominantly marine sediments, the residual basin liquid is primarily a chloride, brine; if the rocks are largely igneous, the residual brine tends to be alkaline containing carbonates, and sometimes borates as well. Since normally, both types of rocks occur in regions contiguous to closed basins, residual liquids do not often fit into the two broad divisions mentioned. No two residual brines are exactly alike, just as no two ore deposits are exactly alike. Even out of the same closed basin, it is possible to get widely different analyses of liquids since underground and surface flows, as well as local evaporation rates and other conditions might have a marked influence on residual-liquid compositions. At Searles Lake, The American Potash and Chemical Corporation is building a plant to process a lower-level brine which is considerably higher in sodium carbonate and borax, and lower in potassium chloride, than that company has processed for many years. F. W. Clarke1 has classified waters of closed basins as follows: I. Chloride type; largely sodium chloride (NaC1) and of oceanic type, such as Great Salt Lake. Related is -the Dead Sea, a bittern residue of magnesium, potassium and sodium chlorides. a. Sulphate type; largely sodium sulphate (Na2SO4) with considerable sodium chloride such as Sevier Lake, Utah; Laramie Lakes, Wyoming; Dale Lake, California. 3. Carbonate type; high in carbonates and fairly high in sulphates, such as Moses Lake, Eastern Washington; and the Nebraska Potash Lakes. 4. Carbonate—chloride type; lower in carbonates than type 3 and about equally rich in sulphates, such as Pyramid Lake, Nevada. 5. Sulphate—Carbonate type; quite high in sulphates and carbonates, such as Pelican Lake, Oregon. 6. Triple type; considerable quantities of carbonates, sulphates and chlorides

Jan 1, 1948

By George D. Dub

Owens Lake is at present a source of important nonmetallic minerals, sodium carbonate (soda ash, Na2CO3); sodium sesquicarbonate (trona, Na2CO3.NaHCO3.-2H2O) and borax, (Na2B4O7.10H2O). Owens Lake is a closed basin in the southern part of Inyo County, California, at the southern end of Owens Valley, east of the Sierra Nevada Mountains and west of the Coso and Inyo Mountains. Broadly considered, it is in the Great Basin area, but at no time was it a part of Lake Lahontan. Closed Basins Closed basins are phenomena of arid or semiarid regions where outflow is considerably less than inflow and where accordingly soluble salts concentrate in residual liquid. When inflowing waters originate in areas where the rocks are predominantly marine sediments, the residual basin liquid is primarily a chloride, brine; if the rocks are largely igneous, the residual brine tends to be alkaline containing carbonates, and sometimes borates as well. Since normally, both types of rocks occur in regions contiguous to closed basins, residual liquids do not often fit into the two broad divisions mentioned. No two residual brines are exactly alike, just as no two ore deposits are exactly alike. Even out of the same closed basin, it is possible to get widely different analyses of liquids since underground and surface flows, as well as local evaporation rates and other conditions might have a marked influence on residual-liquid compositions. At Searles Lake, The American Potash and Chemical Corporation is building a plant to process a lower-level brine which is considerably higher in sodium carbonate and borax, and lower in potassium chloride, than that company has processed for many years. F. W. Clarke1 has classified waters of closed basins as follows: I. Chloride type; largely sodium chloride (NaC1) and of oceanic type, such as Great Salt Lake. Related is -the Dead Sea, a bittern residue of magnesium, potassium and sodium chlorides. a. Sulphate type; largely sodium sulphate (Na2SO4) with considerable sodium chloride such as Sevier Lake, Utah; Laramie Lakes, Wyoming; Dale Lake, California. 3. Carbonate type; high in carbonates and fairly high in sulphates, such as Moses Lake, Eastern Washington; and the Nebraska Potash Lakes. 4. Carbonate—chloride type; lower in carbonates than type 3 and about equally rich in sulphates, such as Pyramid Lake, Nevada. 5. Sulphate—Carbonate type; quite high in sulphates and carbonates, such as Pelican Lake, Oregon. 6. Triple type; considerable quantities of carbonates, sulphates and chlorides

Jan 1, 1948

By P. Lindstrom

Retreat mining, using yielding steel friction props, over a 7-year period has been successful at a uranium mine operated by Hecla Mining Co. in southeast Utah. The support system allows good roof control, maximum profit, complete extraction, and good ventilation. Unusual subsidence observations were made in that some of the surface was raised rather than lowered. Longwall mining, commonly practiced in European coal mines, has a potential of broader application because of mechanization possibilities and better roof control and ventilation at greater depths. The Radon mine was one of the first American metal mines to use yielding steel props for supporting the relaxed core of the pressure arch which is induced by retreating longwall mining. Full caving was induced. After more than 7 years of stoping experience, the method has proved very satisfactory for the conditions encountered. The mine and method have been described in references listed in the bibliography. U.S. Bureau of Mines Information Circular 8004 by Wilbert Dare and Philip Lindstrom gives the most information. Stoping experience at this mine indicates that there are many advantages to be gained by using yielding supports; such as in safety, timber cost, roof control, ventilation, ore dilution, and low cost per pound of metal produced. Subsidence measurements show that the surface will rise rather than slump in some areas over the mine. This appears to be an unusual observation and is presented as a new development in subsidence studies. The Radon mine is located 35 miles southeast of Moab, Utah in the north end of the Big Indian mining district in San Juan County. Hecla Mining Co. operated the mine from early 1955 to early 1964 through an operating agreement with Federal Resources, Inc. Development consisted of a 3-compartment, 690-ft shaft, 4 main levels driven on the ore horizon and a haulage level below the ore. Evaluation of physical and economic factors showed that this flat-dipping ore occurrence could be mined by a low-cost coal mining method. The value of the deposit was high and unusual premiums were possible by clean mining. Complete extraction without loss of ore pillars, minimum ore dilution and high production per man were obtained by longwall mining. The principle of working under the relaxed core of

Jan 1, 1964

By Samuel Hoyt

THE hardness of annealed copper has been given in the literature and is easily obtained by any of the standard methods of hardness testing. It is not our intention to correct published values or to add to them, but to describe tests of two bars of annealed electrolytic copper in which the methods of Meyer's analysis were employed. MEYER'S ANALYSIS OF BALL INDENTATION TEST The ball indentation test is probably the most valuable hardness test we now have but, as it is carried out in the Brinell or Rockwell test, the result may be seriously in error without the operator suspecting such to be the case. This condition results from the isolated and uncontrolled nature of the measurement. The accuracy depends on the accuracy of the equipment and the care and skill used in the operations; there is nothing in the impression diameter, which is all that is measured, to indicate the presence of error. Meyer's analysis supplies a control of the measurements that goes far toward eliminating unsuspected errors. The principles of this work maybe obtained from elsewhere.1 As this subject has not received the attention of this Institute, it may be well to summarize the more important points as follows.

Jan 2, 1926

Contents A - Metal Mining B - Minerals Beneficiation F - Coal H - Industrial Minerals I - Mining Geology L - Geophysics

Jan 11, 1953

For the -year ending February, 1920 PRESIDENT HORACE V. WINCHELL MINNEAPOLIS, MINN. PAST PRESIDENTS PHILIP N. MOORE ST. Louis, Mo. SIDNEY J. JENNINGS NEW YORK, N. Y. FIRST VICE-PRESIDENT A. R. LEDOUX NEW YORK, N. Y. TREASURER GEORGE D. BARRON NEW YORK, N. Y. SECRETARY BRADLEY STOUGHTON NEW YORK, N. Y.

Jan 5, 1919

By Walter Knox, J. D. Doherty

IN 1939, at the request of The Koppers Coal Co., the Koppers Company Research Department established a Stoker Coal Research Laboratory for the purpose of investigating the performance characteristics of stoker coals in typical domestic stoker installations. Fig. I is a photograph of part of the laboratory. The material in this paper deals with the performance of one coal in a single installation. Presented are details of this installation, mechanical characteristics of the stoker, and the results of a series of burning tests in which adjustments were systematically varied. SUMMARY OF RESULTS Mechanical Features I. A large percentage of the total power consumed by a domestic stoker is used to operate the gear case and motor (Fig. 3). 2. The power consumption per ton goes down with an increase in rate of coal feed (Fig. 4). 3. The automatic air control in this stoker showed advantages over manual control (Fig. 5). 4. The air velocities through the retort tuyeres were uniform around the retort, but varied between the rows of tuyere rings (Fig. 6). 5. The crushing of coal with this stoker increased the minus 1/8-in. from 1 1.6 per cent to 19.2 per cent. There was a noticeable segregation of coal as it came from the retort and distribution was not uniform (Fig. 7). 6. Measurement of air entering over the fire showed that with some not uncommon adjustments this air may he a high percentage of the total air supply (Fig. 8 and Table I). Operating Performance I. The removal of clinker was shown to give a period of poor performance characterized by a high fuel-bed resistance and a high percentage of carbon monoxide in the flue gases (Fig. 10). 2. The fuel-bed resistance was found to decrease as the fuel bed built up in a normal response to heat demand after a prolonged hold-fire (Fig. II). 3. With intermittent operation the burning rate was almost always less than the feeding rate. The wide variations were found to be greatly dependent upon the length of the On period and the length of the intervals between On periods (Fig. 12). 4. The maintenance of a low furnace draft led to less fly ash, better clinker formation, and higher efficiencies (Fig. I3). 5. The maintenance of a minimum of excess air also resulted in less fly ash, better clinker formation, and higher efficiencies (Fig. 14). GUIDING PRINCIPLES In planning the investigations, the following principles were adopted: Selection of Healing Equipment.-Use only standard models of stokers and furnaces representative of those widely used.

Jan 1, 1942

By Walter Knox, J. D. Doherty

In 1939, at the request of The Koppers Coal Co., the Koppers Company Research Department established a Stoker Coal Research Laboratory for the purpose of investigating the performance characteristics of stoker coals in typical domestic stoker installations. Fig. I is a photograph of part of the laboratory. The material in this paper deals with the performance of one coal in a single installation. Presented are details of this installation, mechanical characteristics of the stoker, and the results of a series of burning tests in which adjustments were systematically varied. Summary OF Results Mechanical Features I. A large percentage of the total power consumed by a domestic stoker is used to operate the gear case and motor (Fig. 3)- 2' The power consumption per ton goes down with an increase in rate of coal feed (Fig. 4). 3. The automatic air control in this stoker showed advantages Over manual control (Fig. 5). 4. The air velocities through the retort tuyeres were uniform around the retort, but varied between the rows of tuyere rings (Fig. 6). 5. The crushing of coal with this stoker increased the minus 1/8-in. from 11.6 per cent to 19.2 per cent. There was a notice- able segregation of coal as it came from the retort and distribution was not uniform (Fig. 7). 6. Measurement of air entering over the fire showed that with some not uncommon adjustments this air may be a high percentage of the total air supply (Fig. 8 and Table I). Operating Performance ,. The, removal of clinker was shown to give a period of poor performance characterized by a high fuel-bed resistance and a high percentage of carbon monoxide in the flue gases (Fig. 10). 2. The fuel-bed resistance was found to decrease as the fuel bed built up in a normal response to heat demand after a prolonged hold-fire (Fig. II). 3. with intermittent operation the burning rate was almost always less than the feeding rate, The wide variations were found to be greatly dependent upon the length of the On period and the length of the intervals between On periods (Fig. 12). 4. The maintenance of a low furnace draft led to less fly ash, better clinker formation, and higher efficiencies (Fig. 13). 5. The maintenance of a minimum of excess air also resulted in less fly ash, better clinker formation, and higher efficiencies (Fig. 14). Guiding Principles In planning the investigations, the following principles were adopted: Selection of Heating Equipment.—Use only standard models of stokers and furnaces representative of those widely used.

Jan 1, 1942

By Walter Knox, J. D. Doherty

In 1939, at the request of The Koppers Coal Co., the Koppers Company Research Department established a Stoker Coal Research Laboratory for the purpose of investigating the performance characteristics of stoker coals in typical domestic stoker installations. Fig. I is a photograph of part of the laboratory. The material in this paper deals with the performance of one coal in a single installation. Presented are details of this installation, mechanical characteristics of the stoker, and the results of a series of burning tests in which adjustments were systematically varied. Summary OF Results Mechanical Features I. A large percentage of the total power consumed by a domestic stoker is used to operate the gear case and motor (Fig. 3)- 2' The power consumption per ton goes down with an increase in rate of coal feed (Fig. 4). 3. The automatic air control in this stoker showed advantages Over manual control (Fig. 5). 4. The air velocities through the retort tuyeres were uniform around the retort, but varied between the rows of tuyere rings (Fig. 6). 5. The crushing of coal with this stoker increased the minus 1/8-in. from 11.6 per cent to 19.2 per cent. There was a notice- able segregation of coal as it came from the retort and distribution was not uniform (Fig. 7). 6. Measurement of air entering over the fire showed that with some not uncommon adjustments this air may be a high percentage of the total air supply (Fig. 8 and Table I). Operating Performance ,. The, removal of clinker was shown to give a period of poor performance characterized by a high fuel-bed resistance and a high percentage of carbon monoxide in the flue gases (Fig. 10). 2. The fuel-bed resistance was found to decrease as the fuel bed built up in a normal response to heat demand after a prolonged hold-fire (Fig. II). 3. with intermittent operation the burning rate was almost always less than the feeding rate, The wide variations were found to be greatly dependent upon the length of the On period and the length of the intervals between On periods (Fig. 12). 4. The maintenance of a low furnace draft led to less fly ash, better clinker formation, and higher efficiencies (Fig. 13). 5. The maintenance of a minimum of excess air also resulted in less fly ash, better clinker formation, and higher efficiencies (Fig. 14). Guiding Principles In planning the investigations, the following principles were adopted: Selection of Heating Equipment.—Use only standard models of stokers and furnaces representative of those widely used.

Jan 1, 1942