Search Documents

By R. H. Tien

The accuracy of the method of steady-state approximation applied to the problems of heat transfer involving phase change (London and Seban's solution) is improved by defining a "modified heat of fusion" which accounts for the effect of specific heat. An analytical expression for this modified heat of fusion is derived in terms of the actual heat of fusion, specific heat, and surface temperature. Numerical solution for the freezing of iron indicates that the ratio of the modified heat of fusion to the actual heat of fusion increases from 1.04 to 1.4 as the surface temperature decreases from 2700° to 1600°F. The heat transfer process accompanying solidification is complicated owing to the moving solid-liquid interface where the latent heat of fusion is released. Exact analytical solution is available only for a few special cases of freezing problems such as Stefan's1 problem. In a commonly used steady-state approximation method, London and seban's2 solution, the effect of specific heat is neglected. This approximation, however, may introduce some degree of error in mathematical analysis when the temperature of the solid surface is much lower than the freezing temperature, as in the case of freezing metals. In a recent work by Robertson and Schenck,3 the problem of freezing a semi-infinite region with finite surface conductance was programed in a digital computer through the finite difference method. A family of curves for the correction of the London-Seban solution was given in a dimensionless plot for different ratios of heat of fusion and specific heat effect; it was shown that the London-Seban solution when applied to the freezing of a mild steel slab under some particular conditions gave results in error by about 10 pct in the solidification rate. Although the Robertson-Schenck computer result has improved the London-Seban solution to a great extent, lack of generality and the tedious computing procedure have restricted its application. In this paper a "modified heat of fusion" which accounts for the effect of specific heat is defined, and is used instead of the actual heat of fusion in the London-Seban solution. An analytical expression of this modified heat of fusion in terms of the specific heat, surface temperature, and actual heat of fusion is derived by comparing the solutions of Stefan and London-Seban for the case of freezing of a semi-infinite region with constant surface temperature. It can also be extended to the case with finite surface conductance, and the results show good agreement with the Robertson-Schenck computer solution. The expression of the modified heat of fusion, the accuracy of the London-Seban solution, and the temperature distribution within the solid are presented graphically in dimensionless form. Numerical solution for the freezing of iron indicates that the ratio of the modified heat of fusion to the actual heat of fusion increases from 1.04 to 1.40 as the surface temperature decreases from 2700° to 1600°F.

Jan 1, 1969

By A. M. Turkalo

IT is a well-known fact that martensitic steels show a greater resistance to brittle fracture than do pearlitic and bainitic steels. It was, therefore, thought worthwhile to investigate the mode of brittle fracture with respect to structure by studying the effect of various austenite decomposition products on the propagation of brittle fracture in steel by means of electron microscopy. Newly developed replication techniques together with the advantages of the electron microscope such as great depth of field, available high magnification and easy adaptation to stereophotography make electron microscopy very suitable for fracture studies. EXPERIMENTAL PROCEDURE An essentially plain carbon steel containing 0.56 pct C, 1.30 pct Mn, 0.02 pct P, 0.03 pct S and 0.22 pct Si was used in this investigation. The following table gives the heat treatments used to obtain the various austenite decomposition products: The resulting austenite grain size from the 870°C austenitization treatment was about an ASTM No. 7 grain size. The specimens which were 2 in. long, 1/4-in. diam bars were austenitized in a tube furnace through which argon gas was blown. The tube was not, however, air-free and the specimens were not completely oxide-free. Isothermal treatments were done in a lead bath. With the exception of the fully hardened specimen and the one as-isothermally transformed at 300°C the heat treated specimens were notched in the following fashion with a jeweler's saw. A cut about 0.08 in. deep was made perpendicular to the length of the bar. The specimen then was rotated about 45 deg and another cut about 0.08 in. deep was made. In the case of the hard martensitic and bainitic specimens, only one cut was made and the depth was not controlled. The design of the two-cut notch caused fracture to initiate at the point of intersection of the two saw cuts. The specimens were broken at -196°C in a Charpy impact testing machine. In order to hold the specimens securely in the impact machine two square pieces of mild steel were made about 5/8 in. long having the same cross section as that of a standard Charpy specimen but containing a hole 1/4 in. diam through the center of the cross-section. These adapters were slipped over the ends of the test specimen which was then secured tightly by means of set screws in the adapters. The specimen with the adapters was cooled to -196°C in liquid N,, then placed in the impact machine and broken within 3 sec. One half of the broken specimen was used for the electron microscope study of the actual fracture surface. The other half was nickel-plated and a cross section through the notch and fracture was polished for electron microscope examination. Carbon replicas of the fracture specimens for the electron microscope study were made essentially according to Bradley's evaporation technique.' Both direct carbon and two-stage carbon replication techniques were used. In the case of the direct carbon technique, a thin layer of carbon was evaporated first at an angle of about 45 deg to the mean fracture surface and then another film of carbon was evaporated normally to the fracture surface. The carbon replica was freed electrolytically.2 The specimen was made an anode in a 10 pct Nital polishing solution. It was etched intermittently by shutting off the power now and then. The freed replica was washed in 40 to 50 pct water solution of nitric acid for 10 min or so, then washed in water and picked up on a screen for examination. The two-stage carbon replication technique involved first making a primary replica of cellulose * acetate from which a carbon replica was then made. One side of a strip of cellulose acetate wet with acetone was pressed lightly against the surface of the specimen, allowed to dry and then stripped. Prior to the deposition of carbon, which was done at 90 deg to the cellulose acetate replica surface, chromium was evaporated at 45 deg. After the carbon evaporation the cellulose acetate was dissolved in acetone according to the Jaffe method3 leaving the carbon replica preshadowed with chromium for examination.

Jan 1, 1961

By F. C. Holman

It is desired in these notes to record a vein-phenomenon certainly unique in the writer's limited experience, and, as it seems to him, sufficiently rare to be worthy of mention. In the little mining camp of Forbestown, situated in the Sierra Nevada of California, it was announced one day, when the miners of the Cold Banks mine came off shift, that "washed gravel" had been struck on the 265-foot level. To those acquainted with that section and the character of the mine (a gold-bearing quartz-vein) this was a somewhat startling announcement; for, prolific as the State is, we are not in the habit of mixing up promiscuously our vein- and placer-deposits. However, the statement proved to have some foundation. The mine is located at an altitude of about 2700 feet, on the brink of one of the great canyons of erosion characteristic of the drainage of this range. A lateral ravine cuts the vein at right angles, thus making its general strike approximately parallel to the canyon at this point, and with a variable dip of from 20 to 40 degrees towards the canyon. The strong, well-defined vein, often 20 feet wide and more, presents nothing to distinguish it particularly from scores of others in the State, unless if be considered peculiar in the highly crystalline character of its quartz and the nature of the enclosing country-rock, which is metamorphic in the extreme, very hard, devoid of lamination, and in bedding so obscure that it might easily pass—at least on superficial examination—for one of the basic eruptives. Near by in the district can be found a series of slates common to the gold-belt of this range, and within the limit of the company's property is an intrusion of an acid eruptive. On an adjoining claim a granite shows itself. The mine is opened through an inclined shaft sunk on the vein. The ore carries both free gold and sulphurets, the greater part of its value

Jan 1, 1896

By Margaret G. Scroger, Luke L. Y. Chang, Bert Phillips

Using the sealed-system technique, isothermal sections at 1000°, 1400°, and 1700°C for the system Co-W-O hare been determined. The equilibrium data were obtained by microscopic and X-ray diffraction examination of samples winch had been equilibrated in pellet form fit sealed capsules and subsequcelly quenched. The only ternary phase in the system is CoWO, which mells congruentlly at approximately 1280°C. At 1000°C, this ternary phase exists in equilihrinm with all the allows and oxide compounds in the hounding binary systems. At 1400°C, liquid forms in thin oxygen-rick region near the CoWO4 composition and only one phase assemblage in the system (W + WO2 + H'5CV7) contains no In order for tungsten to be used to its full potential as a refractory metal. it is necessary that coatings be developed which will preclude oxidation of the metal. It is true that coatings now in use do protect tungsten for short periods at temperatures near 1700 °C. but no coating has been developed which protects adequately at or above this temperature where the use of tungsten is most required. This situation exists despite the great effort in recent years to develop such coatings. and it has become evident that success in this area can be achieved only after a more fundamental knowledge of the thermochemical and therrnophysical propertics of tungsten oxidation and tungsten -metal oxidation is obtained. In our 1aboratories. a project liclrriel. At 1700°C, tungsten is the ouly solid phase which is stctble, and a large range of compositions melt to two liquids, one metallic and one oxidie. The sealed-system method of etjuilibra lion prevents the determination of the partial pressure of oxygen and the total gas pressure orer the condensed phases at equilibrium. This data is not available and can be obtained only by some other method. We can generalize on these unknowns and indicate that both partial pressure of oxygen and total pressure of the gas phase must increase as compositions change from the W-Co binary toward the oxygen apex and as temperatures increase. has been initiated which is directed at providing some of this fundamental information through a study of metal-tungsten-oxygen reactions and equilibria and the properties of any intermediate phases which result. This paper is based on a part of this program in which the system Co-W-O was studied between 1000° and 1700°C. I) RELEVANT INFORMATION FROM THE LITERATURE A) The Notable Lack of High-Temperature Work on Metal-Tungsten-Oxygen Systems. It should be pointed out that there has been no published report (of which we are aware) which deals with the study of a metal-metal-oxygen system at 1700°C. Also, there has been no report on a complete metal-luugsten-oxgen system at any temperature. As a matter of fact. before this program started. The

Jan 1, 1965

Uranium, discovered in 1949 at Rum Jungle, 40 miles south of Darwin, N. T., was mined and processed to U3O8 from 1954 to 1963 by the Territory Enterprises Pty. Ltd. TEP is a Government company managed by Conzinc RioTinto of Australia Ltd. During this period, the uranium oxide was sold under contract to the Combined Development Agency, a joint Anglo-American uranium procurement agency. When the contract terminated in 1963, more than 31/4 million pounds of uranium oxide had been delivered which had been mined from three open pits. Copper ores, found with the uranium, necessitated the addition of a copper circuit to the concentrator. Copper concentrates containing 12,981 pounds of copper were also produced. Rum Jungle was the largest single industrial enterprise in the Northern Territories and, as such, was an important economic and social factor in this sparsely settled tropical region. To stretch out the life of this enterprise for the above reasons, and with the added possibility that the uranium market might improve, the Commonwealth mined out and stockpiled 650,000 tons of ore containing 9.6 lb of U,O, per ton, which is sufficient to sustain the treatment plant at 200 tpd until about 1971. In the plant, uranium is recovered from solution by solvent ex- traction. Current output is being stockpiled pending suitable market conditions.

Jan 10, 1964

By Victor Lenher

The interest shown recently in selenium and tellurium has brought many requests for an assembling of the analytical chemistry of these two elements. The intention of this paper is to discuss all of the chemical principles utilized in the detection and quantitative determination of these elements, as well as to describe the works methods actually followed by producers of tellurium and selenium in the United States. These methods have been furnished by S. Skowronski of the Raritan Copper Works, H. D. Greenwood of the United States Metals Refining Co., F. F. Colcord of the U. S. S. Lead Refinery, and E. W. Rouse and A. E. Hall of the American Smelting and Refining Company. Occurrence Selenium is found associated with sulfur, to which in many respects it is quite similar. Occasionally deposits of native sulfur, notably those in the Lipari Islands, Kilauea, and Japan, show a red-brown coloration, I which is readily distinguished from that of other sulfur; this red-brown * sulfur contains a small amount of selenium. Not infrequently, the , sulfides of the heavy metals are accompanied by selenium and tellurium, • presumably as selenides and tellurides. The Scandinavian pyrite, which is one of the large sources of European sulfuric acid, when roasted has fur- - nished a large part of the selenium that has come to the United States; it I was in flue dust from the roasting of Scandinavian pyrites that the element was discovered by Berzelius in 1817. Greek and Spanish pyrites also

Jan 1, 1923

By Victor Lenher

The interest shown recently in selenium and tellurium has brought many requests for an assembling of the analytical chemistry of these two elements. The intention of this paper is to discuss all of the chemical principles utilized in the detection and quantitative determination of these elements, as well as to describe the works methods actually followed by producers of tellurium and selenium in the United States. These methods have been furnished by S. Skowronski of the Raritan Copper Works, H. D. Greenwood of the United States Metals Refining Co., F. F. Colcord of the U. S. S. Lead Refinery, and E. W. Rouse and A. E. Hall of the American Smelting and Refining Company. Occurrence Selenium is found associated with sulfur, to which in many respects it is quite similar. Occasionally deposits of native sulfur, notably those in the Lipari Islands, Kilauea, and Japan, show a red-brown coloration, I which is readily distinguished from that of other sulfur; this red-brown * sulfur contains a small amount of selenium. Not infrequently, the , sulfides of the heavy metals are accompanied by selenium and tellurium, • presumably as selenides and tellurides. The Scandinavian pyrite, which is one of the large sources of European sulfuric acid, when roasted has fur- - nished a large part of the selenium that has come to the United States; it I was in flue dust from the roasting of Scandinavian pyrites that the element was discovered by Berzelius in 1817. Greek and Spanish pyrites also

Jan 1, 1923

By Howard S. Strouth

Investors and mining companies in the U. S. have recently shown increased interest in the Union of South Africa. This has been sparked partially by the founding in the U. S. of a large investment trust which will hold substantial shares in many of the leading gold and uranium producers. The average U. S, mining man's judgment of the Union, however, may be somewhat clouded by recent headline news. We are inclined to take a strong dislike to the stern measures of the present Union government with regard to its native majority. Others possibly think of South Africa in krms of a British colony which, under pressure of rising African nationalism, must eventually be abandoned. These concepts frequently suffer for lack of precise information.

Jan 5, 1959

By John C. Bilello

The brittle fracture behavior of cold-worked sintered tungsten was studied over the temperature range 4.2° to 298°K using a high-sensitivity strain measuring system and electronfractography. Similar observations were made on a swaged electron beam zone-refined monocrystal. In sintered tungsten irreversible plastic deformation was observed during cyclic load-unload tests at stress levels well below the fracture stress for all temperatures, but general microyielding could be detected only down to 202°K. For the zone-refined samples macroyielding occurred at all test temperatures with evidence for twinning below -202°K. The fracture stress of the sintered tmgsten was virtually independent of temperature, while the zone-refined crystal showed a 2.3 times increase over the same temperature range. Electronfractography confirmed the presence of numerous rod-shaped and spherical submicroscopic voids which ranged in diameter from 1400 to 4300A in the sintered tungsten; no voids could be found in the zone-refined tungsten. Contrast effects observed on the replicas in the vicinity of certain voids indicated that plastic deformation could be induced by the local stress concentration. It has been suggested that the presence of these voids may be responsible for the low-temperature brittle failure of sintered tungsten. Based m this suggestim und on the evidence obtained here, a dislocatim model is presented to account for the brittle behavior of sintered tungsten. In this model slip, which is induced by the local high stress concentration in the region at the edge of a favorably oriented void, could cause the void to grow to a microcrack of critical size. STUDIES of brittle fracture in bcc metals have led to the well-known experimental relationships between grain size, yield stress, fracture stress, and temperature which have formed the basis for the various dislocation pile-up1-3 or interaction4'= models for slip-induced microcrack nucleation. While microcracks can be nucleated by deformation twins,6,7 there has been no direct evidence furnished by transmission electron microscopy to support conclusively either the Zener pile-up or Cottrell dislocation reaction models for producing micro-cracks in all "brittle" materials. In addition to the "inverse" grain size relationship for yield and fracture stresses the cottrel14 theory predicts that the fracture stress below the transition temperature should behave in a fashion similar to that of the yield stress above this temperature. Such behavior has been verified for several bcc metals.8-10 With reference to both grain size effects and the tem- perature dependence of the fracture stress below the transition temperature, the behavior of sintered tungsten appears anomalous. Early work by Bechtold and Shewrnon 11 showed no apparent temperature dependence of the fracture stress below the ductile-brittle transition temperature (DBTT). They attributed this result to the intergranular nature of the fractures observed. More recent work by Wronski and Four-deux12'13 on considerably purer material did not show any systematic relationship between the fracture stress and temperature below DBTT. The dependence of flow and fracture stresses on grain size is also not clearly established for sintered tungsten. Koo, for example, has shown that the DBTT for sintered tungsten depended chiefly on the annealing temperature and was relatively insensitive to the actual grain size achieved. Using electrofractography and transmission electron microscopy, Wronski and Fourdeuxl3 showed that numerous spherical and rod-shaped submicroscopic voids could be found in sintered tungsten but not in melted tungsten of nominally the same purity. They suggested that these voids could be responsible for the temperature insensitivity of the fracture stress below the DBTT. In the present work the temperature dependence of the fracture stress for high-purity commercially sintered tungsten has been determined. The presence of submicroscopic voids in sintered materials was confirmed, and these were studied in detail to examine the role they could play in nucleating brittle fracture. A dislocation model is suggested which could cause an inherent spherical void to lengthen into a Griffith crack of critical size. EXPERIMENTAL PROCEDURE Commercially sintered tungsten rod was obtained in the as-swaged condition from Sylvania. A zone-refined crystal was obtained from the same source. This crystal was grown by giving three zone passes (at 25.4 cm per hr) to a sintered rod of high-purity tungsten. The rod axis prior to cold working was -15 deg from the [110] direction. Originally the zone-refined rod was -6 mm in diam; it was reduced to -3 mm by eight swaging passes, at high temperatures, with each step having about the same reduction of area. The final swaging step gave a 7.5 pct reduction of area at 1050°C. All swaging operations were performed in a hydrogen atmosphere. For the sintered rod a similar working schedule was employed. Metal-lographic examination of the sintered material revealed that the cold-worked structure had an apparent grain diameter of -25 u transverse to the swaging direction (obtained by the intercept method). In the longitudinal direction cold-worked grains were approximately 1.5 to 2 times their diameter. No distinct fiber structure could be observed optically for the zone-refined rod. The cold-worked structure in the

Jan 1, 1969

By Oscar Johnson

The industry has been canvassed for information on methods of handling grinding steel at milling plants, an important subject overlooked in most descriptive articles on milling plant arrangements. The data collected are offered in this paper as a guide to designers and planners who have loading and storage problems to solve. WITH capacities of milling plants expanding from a few hundred tons per day to many thousand, replenishment of grinding media is an important phase of mill operation. Information on this aspect of milling procedure, solicited from several mining companies, is summarized here. At International Nickel's Copper Cliff concentrator the normally strenuous job of changing rods is considerably simplified by the use of the Garrow rod charging machine, Fig. 1. The overhead crane, Fig. 2, brings a bundle of rods, weighing four to a ton, to the loading platform of the machine, positioned in front of the mill. The rods roll one by one down the slight incline of the platform onto a conveyor which sends them into the mill. A modified version of the Garrow machine, Fig. 3, is used at the Federal mill of St. Joseph Lead Co. An overhead crane places the portable steel structure in position in front of the discharge end of any one of the five 9x12-ft rod mills. It then raises a bundle of about twenty 3-in. rods to the discharge platform of the charging machine. The rods are 11 ft 7 in. long and weigh about 278 lb. By tripping a lever the operator allows one rod at a time to roll onto the inclined rollers. A slight push by the operator sends the rod smoothly into the mill. The Union Miniére du Haut Katanga rod charging machine, Fig. 4, is mounted on a pair of wheels at the forward end with swiveling castors at the back for steering it to position for use or storage. Wheels are equipped with locking brakes to maintain the machine in position while it delivers rods to the mill. The device is made in two parts. The first consists of the base, which carries the supporting wheels, grooved rollers, and drive. The other part serves as the rod deck, which can carry up to six 3-in. x 12-ft rods. A short boom built integral with the base reaches through the mill trunnion and delivers the rods into the mill barrel. Three grooved guide rollers ,are provided to receive the rods from the sloping charging deck. One rod at a time is fed to the rollers and thus delivered into the mill. Two of the rollers are driven by 11/2-hp motor through a V-belt drive. The third roller is driven off the first by a single V belt in a groove below the rod groove and on the same center line. Rods are delivered to the charger by an overhead crane in bundles of three to six as needed. The power is supplied by cables plugged into power outlets, suitably located near the rod mill discharge end. The Oliver Iron Mining Co. uses a rod charger, Fig. 5, suspended from a monorail by cables. It is constructed .of structural steel and has two decks, each capable of carrying five rods of 4-in. maximum diameter. The rods ride in grooved free-turning rollers. Legs extending down from the mill end of the mechanism act as supports when the unit is ex-

Jan 1, 1955

By B. D. Lichter

In a previous paper, Oelsen, Schuermann, and Hey-nertl pointed out the possibility of obtaining complete thermodynamic functions for alloy systems from calorimetric measurements alone. Specifically, if the heat content of a heterogeneous, multicomponent system is known as a function of temperature and composition, then it is possible to derive the heats, entropies, and free energies of formation of liquid phases and of solid intermediate phases of fixed composition. The authors present equations and graphical techniques applicable to eutectic systems and systems with intermediate phases without solid solubility at lower temperatures. eijering has considered possible extension of the treatment to systems with complete solid-state miscibility at lower temperatures; however, experimental difficulties practically restrict the method to systems with very limited miscibility in the solid state. The purpose of this note is to present an alternative derivation of the heats and entropies of formation of liquid phases and of solid intermediate phases from heat-content measurements alone. Fig. 1 shows three types of phase diagram to which the analysis may be applied. If the heat content is determined as a function of composition x, at temperature T, we have quite generally and the heat of mixing of the liquid is obtained directly from heat-content measurements. If the temperature T lies in a two-phase region (solid-liquid) then

Jan 1, 1967

Prospectors were digging silver in the Ray mine area in 1873, and by 1880 high-grade copper ore was feeding a 30-ton copper furnace. In 1910, D. C. Jackling and his associates organized the Ray Consolidated Copper Company, known in mining circles as Ray Con, to exploit the Ray orebody. For 50 years, all mining was underground and the Ray mine was known the world over for innovations in mining methods. It was the first to mine important tonnage (8,000 tpd) by block caving methods. The mill at Hayden, 26 miles (41.6 km) from the mine, kept pace with the new mining methods developed at Ray and in the early 1920's flotation replaced gravity concentration by the vanner machines. First mining by open pit methods began in 1950 and in January 1955 all underground mining was discontinued. The new primary crushing plant, installed in early 1967, featured design simplicity with a low capital cost. The 54 in. gyratory crusher was installed within a total height of 6 1 ft (18.65 m) from the truck dump road bed to the floor beneath the feeder-conveyor under the surge pocket. The crusher is fed by 120-ton trucks dumping from one side only into a 200-ton hopper equipped with a horizontal splitter bar to protect the crusher spider. The crushed ore pocket, of 120 -ton live capacity underneath the crusher, discharges to a 0 to 200 fpm (61.2 mpm), variable-speed, 72 in. by 80 ft long (1.83 m by 24.4 m) sloped belt feeder, probably a first in the industry. Wood-picking stations are provided on either side of the belt so that old mine timbers and tramp iron can be removed from the crushed ore and the wood can be dropped into Dempster containers located below the belt. Counter-weighted finger gates control the bed depth on the belt at 14 in. (356 mm) and a low- level radiation unit automatically maintains a minimum of a 3 ft bed (900 mm) of material on the belt directly under the surge pocket. The conveyor is skirted for its full length and is approximately 60 in. (1.52 m) wide inside its metal skirt liners. Ten impact idlers at 12 in. (305 mm) spacing are provided under the loading pocket and remaining idlers are spaced at 18 in. (457 mm). The belt is 1 ¼ in. (31. 8 mm) thick; and, while it has occasionally been damaged by tramp material, belt life averages 11 million tons. When the belt is changed, the coiled new belt is lowered into position onto one of two belt stands mounted over the feeder, the old belt is cut, and one end is attached temporarily to the new belt. The other end of

Jan 1, 1978

By David R. Mitchell

Many of the difficult operating problems of the preparation of coal for market, of sampling coal shipments and in the utilization of coal are caused by segregation in the coal mass. Segregation may be of two kinds: i.e., "size segregation," in which particles of the same size in a mass of coal containing a range of sizes collect together and "density segregation," in which particles of the same density or specific gravity in a mass of particles of varying density gather together. Mechanics of Segregation Size segregation cannot take place with closely sized coal. As the size range increases, the tendency for size segregation increases. Similarly, cleaned coal with particles of approximately the same specific gravity have very little tendency for density segregation. The wider the density range of particles and the more particles of different density, the greater the chances are for density segregation. The following discussion deals primarily with coal of a wide size range as screenings and of wide density differences as uncleaned or run-of-mine screenings. If a mass of coal containing particles of a wide size range is subject to the stream action of a moving current of water, the small particles are transported farther than the coarser. Particles of different density in a stream of moving water are subject to the laws of classification, the heavier settling out first. The familiar sluice box of the gold miner and the action of rivers and other streams in classifying material according to

Jan 1, 1938

By David R. Mitchell

Many of the difficult operating problems of the preparation of coal for market, of sampling coal shipments and in the utilization of coal are caused by segregation in the coal mass. Segregation may be of two kinds: i.e., "size segregation," in which particles of the same size in a mass of coal containing a range of sizes collect together and "density segregation," in which particles of the same density or specific gravity in a mass of particles of varying density gather together. Mechanics of Segregation Size segregation cannot take place with closely sized coal. As the size range increases, the tendency for size segregation increases. Similarly, cleaned coal with particles of approximately the same specific gravity have very little tendency for density segregation. The wider the density range of particles and the more particles of different density, the greater the chances are for density segregation. The following discussion deals primarily with coal of a wide size range as screenings and of wide density differences as uncleaned or run-of-mine screenings. If a mass of coal containing particles of a wide size range is subject to the stream action of a moving current of water, the small particles are transported farther than the coarser. Particles of different density in a stream of moving water are subject to the laws of classification, the heavier settling out first. The familiar sluice box of the gold miner and the action of rivers and other streams in classifying material according to

Jan 1, 1938

By Alan R. Grant

The Cascade Range of Washington can be considered metallogenetically to be primarily a copper province. Structural and chemical data compiled from examination of numerous copper occurrences in the Cascades indicate a marked parallel of physical conditions for sulfide deposition. In probable order of significance, the environmental criteria are as follows: 1) adjacent or subjacent, postregional metamorphism high-level intrusive activity, most commonly in the time range from 15 million years to 30 million years; 2) transverse northeast trending structural belts which obliquely cut the northwest regional trend of the range; 3) potassium-silica wall rock alteration; most important of the alteration suite of silicates are orthoclase secondary biotite and quartz; 4) the intersection of northwest trending and northeast trending structures. The varying geologic environments in the Washington Cascades present a complex setting for the sulfide deposits. The North Cascades are comprised of predominantly pre-Tertiary metamorphic rocks invaded by Tertiary calcalkaline intrustive rocks. The Central Cascades, lying south of the North Cascades, exhibit a younger, higher level geologic environment comprised of predominantly early to middle Tertiary volcanic rocks and subordinate sedimentary rocks which are intruded by Tertiary calc-alkaline igneous rocks. Although the Tertiary Cascade intrusions are dominantly quartz dioritic, copper mineralization is commonly found in rocks of quartz monzonite to granite composition. These acid rocks appear to be the product of late stage magmatic K alteration of the original quartz diorites. Sulfide concentrations are considered to be in part dependent on the degree of K-silicate activity and the intensity of transverse structural deformation.

Jan 1, 1973

By David K. Hylbert

This study investigated roof falls in room-and-pillar drift coal mines in eastern Kentucky and utilized geologic methods for predicting roof conditions in advance of mining. In the Highsplint mine, the roof was classified in four categories or conditions: Condition A and B (Laminated Shale); Condition C (Rolling Sandstone with Shale in Pockets); and Condition D (Zone of Major Sandstone Roll(s)). Structure contour and isopach maps of the Darby coal bed and associated immediate roof rocks were wed to project axial trends of the sandstone roof. Trend mapping in the mine and on outcrop provided more detailed control for roof projections.

Jan 12, 1978

THE total crude production from the Dutch East Indies, and the British Protectorates of Sarawak and Brunei for 1932 is given in the following table: BARRELS BARRELS (42 GAL.) (42 GAL.) North Sumatra 4,226,935 Ceram 326,207 South Sumatra 13,956,157 Sarawak 2,739,650 Java 3,845,568 Brunei 1,322,725 Dutch Borneo (main island) . 9,406,733 Dutch Borneo (Island of Tara- kan) 6,579,184 Total 42,403,159 Production, which had shown a rapid increase from 1921 to 1929, has since been reduced. Exploitation drilling in the majority of the larger fields was suspended and existing production kept within predetermined limits by beaning. Most of the smaller fields were shut down entirely. The depth of producing levels varies widely in the different fields. Shallow fields with drilling depths to 500 meters (1650 ft.) are still numer-ous as well as those with depths between 500 and 1000 m. (3300 ft.). A few of the newer fields reach greater drilling depths. up to 1600 m. (5250 ft.). The deepest exploration well drilled to date (Djambi field, South Sumatra) reached a depth of 2332 m. (7650 ft.) before abandon-ment in March, 1930. The specific gravities of the various crude oils produced range between 0.65 (86.2° A.P.I.) and 0.95 (17.5° A.P.I.). The lighter crudes have a high gasoline content and fuel oils are derived from the heavier crudes, which usually are rich in paraffin.

Jan 1, 1933

The regular meeting of the Trustees of United Engineering Society was called to order at 4 P. M. Thursday, Feb. 27, 1919, in the Board Room of the American Society of Civil Engineers, Engineering Societies' Building, New York. Minutes of a joint meeting of the Finance Committee of United Engineering Society with finance committees of Founder Societies on Feb. 14, were presented. The President called attention to actions relating to the recataloging of the Library and the support of Engineering Societies Employment Bureau of Engineering Council. The activity of the Employment Bureau was approved and support by the Societies informally assured. In response to a communication from the Fifth Avenue Association, the Secretary was instructed to write favoring the continuance of the daylight saving law. As to recataloging of Engineering Societies Library, it was announced that the Mining, Mechanical, and Electrical Engineers had voted appropriations, as requested, and the action of the Civil Engineers was awaited. A list of applications for offices in Engineering Societies' Building, revised to Feb. 27, was read, showing requests for a total of 29 rooms. The President stated that a decision must be reached soon as to what reply shall he made to these applications. Charles F. Scott, one of the original trustees, who was present, remarked upon the growth of United Engineering Society and his satisfaction at its success. ALFRED D. FLINN, Secretary.

Jan 4, 1919

By Howard E. McKinney

A high-pressure wellhead lubricator has been developed to facilitate telemetering electrical measurements from subsurface reservoirs to the surface with the well under normal flowing conditions. The field unit in use at the present time employs a 5/16-in diameter, single-conductor armored cable and is to be used in wells with surface pressures up to 5,000 psi. It has a pressure sealing element that maintains a continuous and absolute seal around the cable as it enters or leaves the tubing at speeds up to 175 ft per minute. A cable injecting device is used which obviates sinker bars or weight sections on the instrument. INTRODUCTION The development of instruments for securing physical measurements in pressure wells has been confined in the past to those instrument which would operate on a wire line and record the necessary measurements in the downhole instrument itself, or those which would operate on an electric cable in a well with the surface pressure killed by the use of weighted fluids or by the use of tubing plugs. In one case the accuracy of the measurements is questionable, and in the other the range of application is very limited. Considerable work has been done by other interests to provide effective means to accomplish the necessary telemetering. The U. S. Bureau of Mines developed a wellhead lubricator prior to 1947 which permitted a 5/16-in diameter single-conductor cable to be lowered into a well with a surface pressure of approximately 500 psi. This unit was used successfully in a number of tests in Oklahoma. A company which tests wells has recently offered on a service basis a wellhead lubricator with a 3/16-in diameter cable that reportedly operates up to 2,500 psi surface pressures. Each of the above operates on a staging principle to effect a seal. In both of these units some leakage of well fluid occurs when the cable is moved. SPECIFICATIONS FOR DESIGN In order to provide the maximum flexibility in its use, the following parameters were established for the design of our high-pressure wellhead lubricator: L An absolute well fluid seal up to 5,000 psi surface pressures. 2. Means for raising and lowering the instrument at speeds of at least 100 ft per minute. 3. Provision for the instrument to enter and leave the well without disturbing the well flow or the reservoir conditions. 4. A cable large enough to provide suitable electrical characteristics and suitable mechanical properties. 5. A method of operation that will not damage the well in any way. The present high-pressure wellhead lubricator field unit fulfills the above requirements. DESCRIPTION OF THE UNIT AND ITS OPERATION The cable selected for this use is the standard Amergraph 1H2 as manufactured by the American Steel and Wire Co. This particular cable is normally used by the Halliburton Oil Well Cementing Co. in their conventional well logging operations. Although the cable presents a noncircular cross-section (Fig. l), its diameter is very consistent; lor example, maximum diameter is 0.325 in., minimum diameter 0.314 in. This [actor permits the use of the sealing element, as later described. Early in the development of the high-pressure wellhead lubricator it was apparent that we could not effect a direct gas seal around a moving 1H2 cable. This becomes evident when an examination of the cable cross-section is made. The voids between the strands of the outer armor provide natural channels lor the flow and escape in large quantities of a low-viscosity fluid such as gas. However, it is relatively simple to

Jan 1, 1952

By R. W. Freeman, L. L. Tavlarides

The experimental methods used in obtaining kinetic data for solvent extraction systems can affect the validity of the results The method of contacting the two liquids should allow for accurate determination of the surface area, hydrodynamics, and diffusional processes The appropriateness of the Liquid Jet Recycle Reactor is discussed and the modelling of the mass transfer and chelation reaction is presented The LJRR is used to investigate the chelation of copper by LIX65N in toluene from aqueous copper sulfate sulfuric acid solutions The ranges of experimental variables are Copper, 1 8-13.8 g-dm-3, sulfuric acid 0-1.6 g-dm-3, LIX65N, 0 1-1.0 mol-dm-3 Data on the initial rate of copper chelation at the interface is generated Nonlinear regression analysis shows that the following expression adequately describes the data within experimental error.

Jan 1, 1981