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By C. A. Worner

THE meeting of the Petroleum Division at the Annual Meeting of the Institute maintained the high standard set in previous years, and attendance of member: of the Division was at a new high. The impact of the war was evident not only in the tone of many of die papers but also in the presence at the meeting of many of our members now serving in the armed forces of our-country. Ken interest was manifested in all papers presented and the discussions which followed developed many additional facts of interist and importance. The first activity of the Division was the joint meeting of the Papers and Programs and the Publications Committees on Monday afternoon; at which time definite plans were formulated for a simplification and co-ordination of the work of the committees.

Jan 1, 1944

By Robert Mehl

RELATIVELY few data have been collected on the rates of diffusion in ternary solid solution systems. In general it does not seem worth while to gather extensive data for such systems until the factors that determine the rates of diffusion in binary systems are better understood. But the rates of diffusion in a ternary system of limited solid solubility, in which the terminal solid solution is in equilibrium with an intermediate phase and may thus be represented as a quasibinary system, represents a case of special interest. In this case, where by reason of the association of the two solute metals in an intermediate phase a special attraction of the two solute atoms may be safely assumed, some interaction of these atoms during simultaneous diffusion in the solvent lattice might be expected. It has frequently been proposed that molecular solid solutions exist in quasibinary and in other ternary (and binary) solid solutions. There is no direct evidence for such solid solutions; arguments based upon the supposed anomaly in certain physical properties1 are hardly important; unexpected density relationships have proved deceptive ;2 suggestions of molecular solid solutions have been made on the basis of solution laws in their application to certain systems, but without result;3 attempts to find lattice parameters in the solid solution Al-MgZn2, which cannot be calculated from the separate effects of magnesium and zinc and might therefore be taken as evidence for a molecular aggregation, have given negative results.4 Fundamentally, methods for the determination of the state of molecu¬lar aggregation in solution depend upon the kinetic behavior of the par-ticles constituting the system. If it could be shown that the two solutes in a quasibinary ternary system diffuse in molecular proportions, despite a radical difference in the separate rates of diffusion of each solute when diffusing alone in the solvent lattice, some basis for the concept of molecu-lar solid solution would be afforded. Freche5 examined the rates of independent and simultaneous diffusion of magnesium and silicon in

Jan 1, 1939

By S. J. McCarroll

Fig. 1—The belt shown at right carries filter cake to mixing station over calciner. Crude ore conveyors appear in right background. THE Three Kids mine, some six miles east of Henderson, Nev., is in a typical southwest desert area, with high dry summer heat and cool to cold winter seasons. The manganese deposit was located during World War I.' During this period 15,000 to 20,000 tons of ore assaying up to 41 pct manganese were shipped. Interest in the deposit was not revived until the middle thirties, when experiments on the ore were initiated. Test work indicated possible recovery of only 70 pct by flotation, but in 1941 additional work was done at the Boulder City pilot plant of the U. S. Bureau of Mines and also by M. A. Hanna Co. As a result, the Manganese Ore Co. was formed and a plant utilizing the SO2 process was constructed. Numerous operation difficulties ensued, and the plant. was closed when the manganese situation in the country eased. In 1949 Hewitt S. West initiated negotiations to acquire the plant. In 1951 Manganese, Inc., was formed and contract entered into with the General Services Administration to supply 27 million units of metallurgical grade manganese in the form of nodules to the national stockpile. A second contract was made to upgrade 285,000 tons of stockpile ore. Test work was undertaken by the Southwestern Engineering Co. and likewise by the Boulder City pilot plant at the U. S. Bureau of Mines. Results obtained indicated the commercial feasibility of the flotation process. Construction of the plant, which is shown in Figs. 1 and 2, was started in June 1951, and operations on a break-in basis began in September 1952. Apart from the usual starting difficulties two major disasters caused serious setbacks, one a kiln failure in February 1953, and the other a fire that destroyed the flotation building in June of the same year. The nodulizing section of the plant resumed operation in November, and the flotation section in January 1954. The ore minerals are chiefly wad,* with minor amounts of psilomelane, and occur in sedimentary beds of volcanic tuff. The ore is overlain with beds of gypsum which outcrop or may be covered with surface gravel. Intermediate beds of red and white tuff occur frequently with lenses of red and green jasper and stringers of gypsum and calcite. Small amounts of iron are present; lead content averages about 1.0 pct and minute amounts of copper and zinc are found. Barite, celestite, and bentonite are present. Since these are made up of minute asicular crystals, moisture content is very high, averaging about 18 pct. Ore reserves have been estimated at 3 million tons averaging 18 pct Mn2 and up to 5 million tons after grade is dropped to 10 pct Mn. A good part of the orebody was stripped of overburden by the previous operating company . Approximately 50 pct of the ore, representing more than 60 pct of the manganese, can be mined by open-cut methods. A system for underground min- . ing has not yet been decided on. Open-cut mining with benches of 20 ft has proved satisfactory. Although the ore is soft and appears dry and dusty it has a certain resilience, probably due to the porosity and moisture which makes drilling and fragmentation difficult. Wagon drills have been abandoned in favor of the Joy 225-A rotary drill which will put down a 43/4 -in. hole at the rate of 2 ft per min. Holes are spaced in a pattern with 8 to 9-ft centers. Forty percent powder has been used, but better breaking to 2-ft size is obtained with low velocity bag powder of 30 pct strength. Loading is done with one 21/2-yd shovel, and cleanup follows with one D-7 bulldozer. The ore is hauled with Euclid trucks about 1000 ft from the pit to a blending pile, where the daily mine production is spread in layers by bulldozing until approximately one month's mill feed is accumulated. A new pile is then started and mill feed is drawn from the first pile by one 13/4-yd shovel and Euclid trucks, with a haul of approximately 500 ft. Mining is performed by an independent contractor with engineering and supervision by the company staff. Early test work indicated that the manganese could be floated with soap, a wetting agent, and fuel oil to give a recovery of better than 75 pct with a grade of 43 pct Mn. The concentrate when nodulized with coke would upgrade to 46 pct Mn or over, and the lead volatilized to 0.6 pct residual.

Jan 1, 1955

By Walter E. Lewis

Myriad problems face all of us in the next decade. Vietnam, poverty, and pollution are perhaps the most pres- sing. A lesser one but still vital to us as a Nation is the slow hut apparently relentless extinction of the mining, metallurgical. geological and petroleum engineer. Are we doomed to take our place in the crossword puzzle with the moa. to be defined like it as an "extinct bird"? Or can we reverse the trend perhaps, in the next decade? The plain fact is we are an endangered species, and must resign ourselves to virtual extinction in the 1970's unless the trend is reversed. Probably, many of us have felt the problem will solve itself if left in the in-basket long enough, believing, that the trend will reverse solely on the basis of demand for these disciplines. This approach has not worked up to now, it gives no promise of working in the future, and furthermore, the problem has been in the in-basket much too long. The point is simply this: What can each of us do as an individual, or as part of a company, a State agency, a Federal agency, a university, or an organization such as AIME?

Jan 1, 1970

By C. L. Sollenbeger, R. B. Greenwalt

PERHAPS the most widely used dispersants or gangue depressants in nonmetallic flotation are sodium silicates, which vary in silica-to-soda ratio from 1 to 3.75. Typical manufactured silicates in order of decreasing solubility and increasing amounts of silica are Metso, silica-to-soda ratio of 1.00; D, 2.00; RU, 2.40; K, 2.90; N, 3.22; and S-35, 3.75.* References in flotation literature1,2 to the use of sodium silicates are often weak because they fail to mention the type of silicate used. Metso and silicate N have occasionally been mentioned, but when the type of silicate is not mentioned, it is usually assumed to be N, the cheapest of the soluble silicates and the one recommended by sodium silicate manufacturers as a flotation agent. In the All is-Chalmers Research Laboratories a systematic study was made of the effect of different alkali-silica ratios on the concentration by flotation of two scheelite ores. One of these was a high grade ore from the Sang Dong mine in Korea. The effect of such factors as pH; addition agents; and conditioning time, temperature, and pulp density on the flotation efficiency of this ore have been described previously. The other ore was a low grade ore from Getchell Mines Inc., Nevada. The mineralogy and techniques of concentrating this ore have been described by Kunze. Hereafter these ores will be referred to as the Korean and Nevada ores. Experiments were made with both to determine the effect of three factors—-type of silicate, concentration of silicate, and pH of the pulp—on recovery and grade of tungsten in a rougher concentrate. Average WO, content of the Korean ore was 1.50 pct and of the Nevada ore 0.27 pct. The predominant tungsten mineral in both ores was scheelite, which was accompanied by a small amount of powellite. The powellite and scheelite were finely disseminated through both ores and required a —200 mesh grind for liberation. Major gangue minerals in the Korean ore, in decreasing order of abundance, were amphi-boles, quartz, biotite, garnet, fluorite, and calcite. Bulk sulfides composed about 3 pct of the total weight. Gangue in the Nevada ore, in descending order of abundance, was garnet, alpha quartz, calcite, phlogopite, wollastonite, and amphiboles. Sulfide minerals were 3 to 4 pct of total weight. Batch flotation experiments were made with 500-g samples of ore, each sample wet-ground to 90 pct passing 200 mesh. The finely ground ore was floated in a Fagergren batch cell at 25 pct solids. The natural pH of the Nevada ore was 8.9 and of the Korean ore, 8.5. The D, RU, K, N, and S-35 sodium silicates were obtained in colloidal dispersions with varying amounts of water. The most alkaline, Metso, was in dry powdered form. For convenience in addition, 5 pct solutions by weight were prepared from each of the silicates, on the basis of dry sodium silicate dissolved in the correct amount of distilled water. Chemical analyses of the various silicates are given in Table I, together with the pH of the 5 pct solutions. A preliminary bulk sulfide float was made with secondary butyl xanthate as the collector and pine oil as the frother. The WO] analysis of the sulfide concentrate was nearly 1 pct for the Korean ore and about 0.1 pct for the Nevada ore. The tungsten contained in the sulfide concentrate constituted about 3 pct of the total tungsten in each ore. No effort was made to recover these tungsten values. The scheelite was floated with oleic acid. Adjustments in pH were made with sulfuric acid or sodium carbonate. A 1 pct solution of 85 pct Aerosol OT was sprayed on the froth and sides of the cell during the scheelite float to aid in dispersing the minerals and to decrease the entrapment of gangue particles. Six tests were planned for each of the six types of silicate in which concentrations of 1, 2, and 4 1b of silicate per ton of dry ore were investigated at both 6.5 and 10 pH. All tests were made at room temperature. The performance of each silicate was judged from the grade and recovery of WO, in the scheelite rougher concentrate. Tungsten recovery was calculated on the basis of the scheelite remaining in the ore after the preliminary sulfide float. Testing of each silicate at three levels of concentration and two levels of pH required 36 tests with each scheelite ore. Variance analyses were performed on the concentrate grades and recoveries to determine whether or not the type of sodium silicate, the concentration of sodium silicate, or the pH significantly affected recovery or grade. Results Concentrate Grade: A variance analysis of the concentrate grades for the Korean ore showed that concentration of the silicate and pH of the ore pulp were major factors in producing a high grade concentrate. Also, the silica- to-so da ratio was important as an interaction with pH. The concentrate grade vs silica-to-soda ratio is plotted in Fig. 1. The curves show that the concentrate grade improved with an increase in concentration of sodium silicate and also

Jan 1, 1959

By AIME AIME

IN an address before the New York Section. A.I.M.E., Oct. 20, Alex L. ter Braake, speaking on the tin industry of the Netherlands East Indies, interjected a few remarks, at the chairman's request. on the mineral stock-piling project now before Congress in a bill sponsored by Senator Scrugham. The full text of Mr. ter Braake's paper was published in the Nov. 6 issue of the American Metal Market. Following mention of the buffer stock scheme as applied in the tin industry, Mr. ter Braake continued:

Jan 1, 1943

By Jack G. Gill, Richard A. Dick

Blasting safety is a subject that cannot be overemphasized. Two years ago, a study was published describing g a series of fatal blasting accidents which took the lives of ten metal and nonmetal miners during the period of May 1973 to August 1974.1 Each accident was described, and the direct causes were delineated. In each instance, specific MESA safety regulations were violated. Four of the victims were killed by drilling into explosives; two were killed by lingering too long in the vicinity of fuse rounds; two fatalities resulted from improper guarding of shots; one blaster did not retreat far enough to avoid the blast concussion; and another used an improper tester for checking an electric blasting cap. All of these fatalities could have been avoided by adhering to the MESA blasting regulations contained in 30 CFR Part 55 (Health and Safety Standards-Metal and Nonmetallic Open-Pit Mines), Part 56 (Health and Safety Standards-Sand, Gravel and Crushed Stone Operations), and Part 57 (Health and Safety Standards-Metal and Nonmetallic Underground Mines).

Jan 11, 1977

By M. R. J. Wyllie, F. Morgan, P. F. Fulton

The importance of formation factor, F, not only in electric logging but as a fundamental rock parameter has recently been stressed.',: The desirability of investigating the range of variation of the resistivity index exponent, n, in the relationship I = S ;", where I is the resistivity index and Sw the water saturation as a fraction of the void volume of a porous medium, has also been urged.3 The magnitude and variation of n with saturation and rock texture is a subject not only of theoretical interest but also one of prime importance in the interpretation of electric logs. A simple technique has recently been developed which enables both F and u to he measured with high accuracy and which may also find acceptance as a convenient method for the determination of irreducible saturation attainment in the restored state method of core analysis. Experience has taught that reproducible measurements of F are possible only if the resistance measuring electrodes are so arranged with respect to a plane face on a porous medium that they are able to make electrical contact with substantially all entry pores in that plane. In practice this may be achieved by using a platinized-platinum gauze electrode backed by some absorbent material (such as felt) which has been saturated with a fluid identical with that used to saturate the porous medium. Applicatiorl of pressure to the electrode and absorbent material then forces the gauze against the plane face of the porous medium and simultaneously squeezes saline solution through the meshes of the gauze. By this means the electrode is in continuous aqueous contact with all pores and satisfactory and reproducible low resistance contact with the porous medium is achieved. Clearly this method, although satisfactory for measurements of F, cannot be applied to the making of continuous resistance measurements on a porous medium while capillary pressure desaturation is being carried out. However, accepting the principle that for satisfactory results electrical contact must be made between a measuring electrode and all pores adja- cent to that electrude, methods of bringing electrodes into intimate contact with the surfaces of porous media were investigated. Two methods were ultimately found to be satisfactory: in the one, the metal electrode is formed on the required portion of the porous medium by the use of a metal spray gun, while in the second the electrode is painted on with an ordinary camel's hair brush. The first method has the advantage of permitting the use of any metal which can be sprayed, but has the disadvantage of requiring rather elaborate and expensive equipment. The second method is presently limited to silver electrodes although in principle other metals, e.g. platinum or gold, could be used. Moreover, the method is so simple and cheap, and has been found to be so satisfactory that it will be described in some detail. The core being investigated is cut into a right circular cylinder and is extracted and dried in the usual manner. The ends are then lightly painted with silver conducting paint* of the type used in printed electrical circuits. The quantity of paint used is not critical but the recommended, minimum compatible with entirely coating the core ends is recommended, particularly on the end that contacts the barrier. The core is then dried at atmospheric temperature for one hour or for shorter periods at any suitable elevated temperature up to about 110°C. It will be found that silver coatings so prepared are not only strongly adherent but also permeable and the core may be the core may be desaturated by the ordinary capillary pressure technique through one of the coated faces. The same permeability is characteristic also of thin metal coatings formed using the spray-gun technique. An ordinary Lucite capillary pressure desaturation cell has been adapted to a form suitable for measuring the resistivity of the saturated silver faced cores both at 100 per cent saturation (i.e., F) and at intermediate saturations down to the irreducible minimum. This has been achieved as follows: A Coors porcelain barrier, having a displacement pressure of c 30 psi was grooved across a diameter. Dimensions of this groove were c 1 mm deep and 1 mm wide at the top. The groove was then painted thickly with silver conducting paint, the paint in the groove being extended lightly over the edges of the groove for a distance of c 1 mm on each side. A 30 gauge silver wire was then arranged in the groove in a form of a spring bow, each end of the silver being held at diamet~ically opposite ends of the groove by means of plastic cement. The arc of the bow at its highest point was arranged to be a millimeter or so above the face of the barrier, while one end of the bow wire was led by means of a pressure-tight connection through the wall of the capillary pressure cell. The groove in the barrier was then Surrounded by suitably cut portions of Kleenex in the conventional manner so as to ensure capillary continuity from core to barrier, and the core placed on the barrier. The weight of the core distorted the silver spring bow and good electrical contact was thereby made between the outside of the cell and the lower painted silver electrode. Electrical connection to tile top painted silver

Jan 1, 1951

By M. R. J. Wyllie, F. Morgan, P. F. Fulton

The importance of formation factor, F, not only in electric logging but as a fundamental rock parameter has recently been stressed.',: The desirability of investigating the range of variation of the resistivity index exponent, n, in the relationship I = S ;", where I is the resistivity index and Sw the water saturation as a fraction of the void volume of a porous medium, has also been urged.3 The magnitude and variation of n with saturation and rock texture is a subject not only of theoretical interest but also one of prime importance in the interpretation of electric logs. A simple technique has recently been developed which enables both F and u to he measured with high accuracy and which may also find acceptance as a convenient method for the determination of irreducible saturation attainment in the restored state method of core analysis. Experience has taught that reproducible measurements of F are possible only if the resistance measuring electrodes are so arranged with respect to a plane face on a porous medium that they are able to make electrical contact with substantially all entry pores in that plane. In practice this may be achieved by using a platinized-platinum gauze electrode backed by some absorbent material (such as felt) which has been saturated with a fluid identical with that used to saturate the porous medium. Applicatiorl of pressure to the electrode and absorbent material then forces the gauze against the plane face of the porous medium and simultaneously squeezes saline solution through the meshes of the gauze. By this means the electrode is in continuous aqueous contact with all pores and satisfactory and reproducible low resistance contact with the porous medium is achieved. Clearly this method, although satisfactory for measurements of F, cannot be applied to the making of continuous resistance measurements on a porous medium while capillary pressure desaturation is being carried out. However, accepting the principle that for satisfactory results electrical contact must be made between a measuring electrode and all pores adja- cent to that electrude, methods of bringing electrodes into intimate contact with the surfaces of porous media were investigated. Two methods were ultimately found to be satisfactory: in the one, the metal electrode is formed on the required portion of the porous medium by the use of a metal spray gun, while in the second the electrode is painted on with an ordinary camel's hair brush. The first method has the advantage of permitting the use of any metal which can be sprayed, but has the disadvantage of requiring rather elaborate and expensive equipment. The second method is presently limited to silver electrodes although in principle other metals, e.g. platinum or gold, could be used. Moreover, the method is so simple and cheap, and has been found to be so satisfactory that it will be described in some detail. The core being investigated is cut into a right circular cylinder and is extracted and dried in the usual manner. The ends are then lightly painted with silver conducting paint* of the type used in printed electrical circuits. The quantity of paint used is not critical but the recommended, minimum compatible with entirely coating the core ends is recommended, particularly on the end that contacts the barrier. The core is then dried at atmospheric temperature for one hour or for shorter periods at any suitable elevated temperature up to about 110°C. It will be found that silver coatings so prepared are not only strongly adherent but also permeable and the core may be the core may be desaturated by the ordinary capillary pressure technique through one of the coated faces. The same permeability is characteristic also of thin metal coatings formed using the spray-gun technique. An ordinary Lucite capillary pressure desaturation cell has been adapted to a form suitable for measuring the resistivity of the saturated silver faced cores both at 100 per cent saturation (i.e., F) and at intermediate saturations down to the irreducible minimum. This has been achieved as follows: A Coors porcelain barrier, having a displacement pressure of c 30 psi was grooved across a diameter. Dimensions of this groove were c 1 mm deep and 1 mm wide at the top. The groove was then painted thickly with silver conducting paint, the paint in the groove being extended lightly over the edges of the groove for a distance of c 1 mm on each side. A 30 gauge silver wire was then arranged in the groove in a form of a spring bow, each end of the silver being held at diamet~ically opposite ends of the groove by means of plastic cement. The arc of the bow at its highest point was arranged to be a millimeter or so above the face of the barrier, while one end of the bow wire was led by means of a pressure-tight connection through the wall of the capillary pressure cell. The groove in the barrier was then Surrounded by suitably cut portions of Kleenex in the conventional manner so as to ensure capillary continuity from core to barrier, and the core placed on the barrier. The weight of the core distorted the silver spring bow and good electrical contact was thereby made between the outside of the cell and the lower painted silver electrode. Electrical connection to tile top painted silver

Jan 1, 1951

By John V. Beall

Our moment of truth is in the offing. When the SME Directory is published in this July issue of [8:] we will know how good or how bad our system is for this computerized Directory. At this writing we have not seen the printout. The SME Directory is designed for maximum utility by the membership but this, of necessity, makes the job complicated. In the alphabetical section, names are listed last name first, followed by codes indicating the class of membership, year of election and divisional interests of each Member. This information is followed by job title, company division, company name and address complete with zip code, or simply by the mailing address of the Member in cases where he either has no company or has not supplied the company information.

Jan 1, 1971

The object of crushing and grinding for leaching is obviously to permit contact of the solvent and mineral and subsequent removal of pregnant solution in a reasonable time. Heap leaching is the leaching of ores that have been mined and transported to prepared, relatively impervious pads for leaching by sprinkling or ponding, and percolation of the lixiviate through the ore. Dump leaching is the leaching of dumps or low-grade ore or overburden without the use of prepared pads under them. Run-of-mine material, e. g., low -grade ore from open pit stripping operations, may be leached without crushing, and a fairly high recovery made by heap leaching. An alternate method for better grade gold/silver ores is to crush to 9 to 13 mm (318 to112 in. ) size for pad heap leaching, as used by Smoky Valley Mining Company at Round Mountain, Nevada, on gold ore, and to 38 rnrn (1 -1 12 in.), which will be done by Candelaria Partners, at Candelaria, Nevada, on silver ore. Heap leaching of copper probably began at Rio Tinto, Spain, about the year 1752. This was done by the leaching of weathering piles of ore in the open air followed by iron cementation of the liquor that drained off the heaps. Its application to the low -grade southwestern United States copper ores was overlooked for many years, and low- grade ores from Sacramento Hill at Bisbee, Arizona, were the first to be heap leached in 1923. Site preparation used a half century ago is the same today. "The need for some form of waterproofing of the pad was evident. Before leaching ore was piled, the site was cleared of cactus and brush. After clearing a gentle sloping area, it was then covered with a blanket of rolled and tamped clay or slime tailing. When heaps are built, a layer of coarse fragments may be put down first to assist drainage. A second method of leaching without grinding, usually for higher grade ores, is by vat or tank leaching of material crushed to 9 to 13 mm (318 to 112 in.) size. Such a plant is considerably more expensive than a heap leaching installation but much less costly than grinding for agitation leaching, and a recovery higher than that obtained by heap leaching is to be expected. Vat leaching has been widely used by the copper industry on higher grade copper ores but has been used in only a few small operations on that size gold or silver ores. However, such a plant should be considered for a modest tonnage of a few million tons, 3 to 7 g per mt (0.10 to 0.20 oz per st), of Carlin-type leachable ores crushed to 9 mm (318 in.).

Jan 1, 1981

By J. B. Cohen, S. L. Sass

The nucleation process for y', Ni3Ti, is shou'n to change from heterogeneous to uniform as the undercooling within the phase boundary increases. As unifornz nucleation beconres copious, (100) alignment is observed in the early stages of aging; howecer. whether or not the alignment is due to spinodal decomposition could not be determined. The presence oi a large-scale reversible segregation of titanium and not the intermediate precipitate y' may be the cause of the initial strengthening in this alloy system and the discrete regions detected magnetically by Ben-Israel and Fine. Evidence is presented for the role of dislocations in the formation at long aging tines oJ the equilibrium precipitate . ThE nickel-rich portion of the Ni-Ti phase diagram consists of a terminal fcc solid solution of titanium in nickel called y.' For temperatures below 1290°C if the solubility limit is exceeded and the temperature is high enough, the excess titanium will combine with nickel to form q, Ni3Ti, a four-layer hcp ordered structure with stacking sequence ABAC."~ Since a change in structure is involved, formation of q is slow and a metastable precipitate referred to as y' forms. This metastable precipitate is an ordered cubic phase in the unconstrained state having a structure similar to Cu3Au (LIZ) with the composition Ni,Ti."'5 From X-ray studies,8, 7 the following sequence is indicated for the precipitation reaction at low temperatures: 1) The appearance of satellites around low-index diffraction spots and splitting of high-index spots, indicating the formation of a slightly tetragonal phase in an imperfectly periodic arrangement. The tetragonal phase is y' or the depleted matrix, depending on the volume fractions of matrix and precipitate (and hence, the alloy composition); tetragonality apparently arises from coherency strains. 2) The appearance of diffraction spots from the equilibrium second phase, q. Ben-Israel and Fine'" used magnetic methods to measure the changes in matrix composition during aging, and to estimate the precipitate composition in a Ni-10.1 at. pct Ti alloy. They observed that the alloy, solution-treated at 1270°C and quenched, contained heterogeneities with discrete compositions which gradually vanished upon aging. It was suggested that y' may initially form as a defect structure with several possible compositions deficient in titanium as compared to Ni3Ti; the composition Ni3Ti develops with prolonged aging. The initial composition was Ni6Ti which would require a very large deviation in stoichiometry for y'. It was noted that at 700°C the precipitation reaction was 80 pct complete after 2 hr and that the volume fraction of second phase was 0.2 after 1 hr. Mihalisin and Decker' suggested that the equilibrium precipitate, besides being nucleated at grain boundaries, could also form at stacking faults. ~errick" examined the formation of in Ni-Cr-Ti, and suggested that a collapsed vacancy cluster within y' acted as a nucleus for intragranular q at high temperatures, 820" and 900°C. After long aging times at lower temperatures, 650" and 750°C, diffraction patterns taken from regions containing ribbons of stacking faults showed spots associated with q. Aging greatly enhances the mechanical properties of these alloys, even at high temperatures, and the metastable precipitate y' is thought to be responsible.' At 600°C the hardness of a Ni-10.1 at. pct Ti alloy increases rapidly during the first 20 hr of aging and continues to increase slowly thereafter.'" At 700°C the hardness reaches a maximum at 1 to 2 hr and then decreases.l1 In this paper the kinetics of formation of y' and the mechanism of transformation to in a Ni-Ti alloy are described. Evidence is presented that suggests that large-scale regions of titanium segregation are present initially and these may have an important influence on the initial strengthening of the alloy: these regions may be the heterogeneities detected by Ben-Israel and Fine. I) EXPERIMENTAL TECHNIQUES The Ni-10.3 at. pct Ti-0.6 at. pct A1 alloy was prepared by vacuum melting. Its chemical analysis is given in Table I. A 0.007-in.-thick strip was sandwiched between foils of the alloy and placed in an open Vycor tube with titanium chips (to get oxygen) and solution-treated for ; hr at 1150°C in a Globar Furnace under a flowing argon atmosphere. Following a quench into an ice-brine mixture at -5" to -2"C, a sample to be aged at temperatures up to and including 700°C was sealed in an evacuated Vycor capsule before being put into a fused salt bath. Aging above 700°C was carried out on bare samples in a salt bath. When removed from this bath and quenched into an ice-water mixture, the sample was normally coated with a thin layer of oxide easily removed with emery

Jan 1, 1970

By M. R. Geer, J. D. Davis, H. F. Yancey

ALTHOUGH the mechanical cleaning of coal is carried out at plants on the surface, preparation is actually begun at the face in the mine. Here the character of the coal and the amount, character, and distribution of the impurities within the bed may be seen. Blasting methods, dust-allaying procedures, location of mining cut with respect to bands of impurity, and the practice of discarding segregated impurities underground, all have an important bearing on the successful operation of surface cleaning units. The most important single characteristic of both coal and its asso¬ciated impurities from the standpoint of cleaning is specific gravity. Other characteristics related in one way or another to the preparation of coal are rank, petrographic composition, structure and hardness, and friability. These and still other coal properties are discussed in the first section of this chapter and impurity characteristics in the second. COAL CHARACTERISTICS RELATED TO PREPARATION Rank As a result of work done over a period of several years by committees of the American Society for Testing Materials and the American Standards Association, standard specifications are now available showing the classification of coals according to rank and quality of grade.' The term "rank" expresses the degree to which the original coal-forming material has been changed by metamorphism through successive stages from peat to anthracite. Table 1 shows the classification of coals according to rank as devised by the committees of the organizations mentioned. The basic scheme of classification for the higher-rank coals is according to

Jan 1, 1943

By C. E. Birchenall, W. Batz, H. W. Mean

AT temperatures between 1095' and 1347ºC, 13 runs have been made on the diffusion of silicon in iron. In two of the runs the couple compositions were entirely within the loop of the Fe-Si system; the base alloys contained 0.0 and 1.0 wt pct Si. The other runs in which the couples consisted of a 2.3 wt pct Si alloy welded to a 3.7 pct Si alloy were a phase throughout. The alloys were made by melting electrolytic iron and commercially pure silicon. Trace impurities were not determined. The butt welded couples were diffused in an inert atmosphere of argon or hydrogen. After cooling, cuts of two mils or greater thickness were machined parallel to the weld interface. The chips were analyzed for silicon. When the concentration and distance data were examined on the conventional probability plot,' no marked variation of the diffusion coefficient with concentration was indicated over the narrow composition ranges employed. Therefore, a single diffusion coefficient is recorded for each run in Table I. The temperatures and atmospheres of the diffusion anneal are listed along with the compositions of the base alloys. For a iron the silicon diffusion coefficient is given by the equation: D = 0.44 e-48,000/RT where R is the gas Constant and T, the absolute temperature. However, since the scatter in the data is fairly large, the activation energy may be in error by as much as 6000 cal per g-atom. The two ? iron points do not permit estimation of the activation energy with any reasonable certainty. They do indicate that the coefficients reported by Smithells2 and Jost,3 based on the work of Fry,4 are much too high. Although very dilute solutions in iron of manganese,5 nickel,8 cobalt,7 and molybdenum8 give dif- fusion coefficients quite close to those obtained for self-diffusion in iron, the silicon values are considerably higher, though of the same order of magnitude. This seems to be consistent with the fact that the silicon atom is the only one of those listed here which is appreciably smaller than iron. The authors are grateful to the Office of Naval Research for their support of this work under Contract N6ori-47, Task order IV, Project NR 031-184, to J. K. Stanley and the Westinghouse Research Laboratories for the silicon alloys used, to several steel companies for the silicon analyses, and to C. Wells, of the Metals Research Laboratory, Carnegie Institute of Technology, for numerous suggestions during the course of the work. References 'C. Wells: Atom Movements (1951) Chapter 2. A.S.M. 2C. J. Smithells: Metals Reference Book (1949) p. 405. Interscience. Pub. Co. 3W. Jost: Diffusion (1952) p. 223. Academic Press. 4 A. Fry: Stahl und Eisen (1923) 43, p. 1039. T. Wells and R. F. Mehl: Trans. AIME (1941) 145, p. 315. "C. Wells and R. F. Mehl: Trans. AIME (1941) 145, p. 329. 7M. F. Hawkes and R. F. Mehl: Trans. AIME (1947) 172, p. 467; Metals Technology (August 1947). .J. L. Ham: Trans. A.S.M. (1945) 35, p. 331.

Jan 1, 1953

By J. J. Kramer, W. A. Tiller, G. F. Bolling

The temperatures of solid-liquid interfaces have been measured during the growth of Sn-Pb alloy crystals which exhibited a cellulur substructure. A simple descriptive theory was used in combination with this data and the other measurable growth variables to predict some features of the solute segregation such as the intercell excess concentration and the depth of cell grooves during freezing. The effective distribution coefficient at the tip of a cell, a, was predicted and experimentally found to vary in the range, 1 >a > k0. At the lower limit, the severe segregation that must arise between dendritic cells was substantiated by various observations such as the existence of a second Phase even for alloys of only 0.2 wt pct Pb. ThE cellular morphology of a solid-liquid interface is known to coincide with the formation of a zone of constitutional supercooling ahead of the interface during growth.' The occurrence of various cell structures, (two-dimensional cells, regular cells, dendritic cells), has been quantitatively investigated,'2,4 but the segregation of solute which arises as a consequence of this mode of growth has only been examined qualitatively. An indirect method of obtaining the solute concentration at the tip of a cell cap during solidification has been de-

Jan 1, 1963

By T. Egleston

The materials containing copper which are refined in the United Statrs, are, for the most part, the natiye noppers of Lake Superior. IJntil quite recently but little pig copper Was made for sale, and that came principally from the pure sulphorous ores of New England and the Sonth, and was generally sdd to reSneries not far from the ore filrnaceu. A stnall aiuoiint found its way into the'niarket which was produced either as the by-product of the treatment of gold and silver ores, or as the result of the treatment of impure copper ores; but both these grades, on account of the impurities they contained, were loolced on with stlspicion, and were not sought for. A11 the grtlGis of pig coppcr are sold by the unit of oopper contents, a great redtiction being made in the price when impurities are present. There are at the present time only three works which treat native copper, the two of the Detroit and Lake Superior copper Company, and the works of C:G. Hussey & Co., in Pittsburgh. There are a few works ivhich smelt sulphuroris ores and refine their pig; bo sides these t1le1-e arc a few siuall works where gig copper is refined uuly. Some of these purcIlase blscir copper, refine scrap, or simply refine such grades of ingot copper as are found in the market, but nlostly that from Lake Superior, for the purpose of getting it into swh shapes that can be handled cpmtriercially to advantage, such as in making large plates or high grades of wire fir electrical purposes. A nomher of such works are situated in the Xaugaturk Vatley aud elsewhcre in New England. The recent discoveryof vnlt~sblc ores in Ariarona makm it probable that within a few year8 the refining of capper In the United States will make great develupments. Up to the time of the discovery of the mines on Lake Superior, only a very small quantity of native copper had ever been foond, not sufficient to justify the erection of worlrs fbr its special treatment. It had, besides, never been found in very large maweq so that the discovery of greabblocks of it presented serious difficulties, not oolp in mining it,-I- but in bringing it into a merchantable condit'ion. It seemed a very simple process to melt these large maws,

Jan 1, 1881

By AIME AIME

MEMBERS of the Engineering Education Committee held two meetings at Joplin preliminary to the opening of the main meeting there. The first was held on Sunday afternoon. It was attended by all who had arrived early enough and as among the dozen or' fifteen who were present the heads of a half dozen schools of mines were included it was a representative gathering. C: H. Fulton, chairman of the Committee presided and T. T. Read acted as secretary of the meeting. The chair., man reminded those present that last year there had been some discussion as to the advisability of the proposal, made by Edward Steidle, that a, separate society, devoted to education in the mineral industry, he organized. Many .people had felt that there are already so many societies in existence to demand one's time and attention, that it would be a mistake to add to their number and the counter suggestion had been made that the work of this committee could be so reorganized as to meet all the needs that a separate society could fill. He therefore presented for discussion these four' questions: (1) Shall a subcommittee .be appointed to study, and report in February, 1932, the possibility of the reorganization of the work of the Engineering Education Committee into the equivalent of an' Institute division; (2) if the work is so reorganized what shall be the relation of the work of the Committee (division) to the work of the-Society for the Promotion of Engineering Education; (3.): what are the, cardinal objectives of education for the mineral industry; and (4) what should be done as regards the movement in some institutions to plan their work-in the light of that being done in other institutions, for example, in geophysics?

Jan 1, 1931

By Harold R. Larson, John F. Elliott

The standard free energies of formation of several nzetallic sulfides have been measured by a reversible electromotive-force cell employing stabilized zir-conia as the electrolyte. The oxygen potential at the cathode was fixed by the use of pure oxygen gas at 1 atm. It was established at the anode by bringing to equilibrium the reaction between the sulfide and oxide species present. Thus, Gf: for the sulfide could be obtained from the cell potential and the standard free energies of formation of the oxides participating in the reaction. The results in calories per cam rnole for the temperature range 850" to 1100°C are: Use of the reversible electromotive-force cell having an oxide-ion electrolyte to obtain the standard free energies of formation of some of the more stable metallic sulfides offers a convenient experimental method that is very productive. It also avoids some of the problems inherent in the experimental methods' for such studies which rely on precise determination of gas compositions, particularly if these compositions lie near the limits of our capabilities for accurate chemical analyses. The reaction equilibrium between the lowest sulfide of a metal, SO2 at a fixed pressure, and an oxide of the metal has a characteristic oxygen potential. For example: and for metals whose lowest sulfide is much more stable than the oxides of the metal, the equivalent reaction might be:

Jan 1, 1968

By M. W. BERNEWITZ

ALL live producers and manufacturers of metals and alloys are investigating new uses for their products. The tin and tin-plate industry is no exception. One-third of all the new tin mined and refined is consumed in making tin plate. Several billions of cans are each year made from tin plate for the preservation of nearly 200 kinds of food. There are more than 500 tin-plate mills or individual stacks in the United States, which country makes more tin plate than all other countries combined and exports large quantities. As much as 1,800,000 tons of till plate has been made in a year in this country, and 28.000 tons of tin has been used in this period for this purpose. In sonic years a third of the till is so consumed; in 1933 it was half of the supply.

Jan 1, 1935

By M. R. Tek, L. K. Thomas, D. L. Katz

Threshold displacement pressures are needed to determine how much overpressure can be used in storing natural gas. An experimental technique for determining threshold pressures by displacing water with gas from samples saturated with water is presented. Threshold pressures for eight low permeability samples were measured. Threshold pressure data obtained in this work, plus data on higher permeability samples reported in the literature, are correlated with porosity, permeability, surface tension and formation resistivity factor. Mercury injection pressures also were measured and correlated with air-water threshold pressures. Threshold pressures were found to be independent of time. An aerial photograph of gas emerging from the top of a core shortly alter its threshold pressure has been exceeded shows that the gas bubbles are uniformly distributed across the face of the core. Channeling will occur, however, when an increased gas phase permeability is reached, A porous medium can be re resealed alter its threshold pressure has been reached, provided it has not been desaturated below a fixed saturation. Its new threshold pressure will be lower than when the sample is 100 percent saturated with water. INTRODUCTION The degree of overpressure in excess of the discovery pressure that a gas storage reservoir can withstand is determined by the ability of its caprock to contain gas, providing the pressure does not exceed the structural limit of the reservoir. The retention of gas in a reservoir by a caprock saturated with water is a result of the capillary forces acting at the gas water interface. Without the presence of water in a caprock, gas would leak out of the reservoir at a rate determined by the permeability of the caprock to gas. The ability of a caprock to contain gas is expressed in terms of its threshold displacement pressure, which is defined as the minimum pressure needed to initiate the displacement of a wetting phase by a nonwetting phase from a porous medium 100 percent saturated with the wetting phase. The gas industry must be able to predict how much "overpressure" a gas reservoir can withstand before leakage occurs by gas displacing water from caprock overlying the reservoir. This is of economic importance since the storage capacity of a gas reservoir is proportional to its pressure. The discovery pressure for most reservoirs is found between the upper and lower limits1 shown in Fig. 1. Discovery pressures in excess of their hydraulic pressure gradient are attributed to the compaction of an isolated shale formation by the overburden.2.3 The lower limit of 0.433 psi/ft corresponds to the weight of the overburden, the gradient of the rock itself. Somewhere between

Jan 1, 1969