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By C. S. Smith

The partial persistence of grain size and grain shape on melting and resolidifying crystalline substances, as well as the general effects of pre-solidifi-cation and of superheating on nuclea-tion rate, have been attributed to the presence in the liquid of crystalline impurities bearing some structural relation to the principal solid and hence capable of serving as nuclei for its crystallization. That such lattice matching does sometimes occur is well established, but it is surely improbable that a compound possessing both high-temperature stability and the requisite structural similarity should be naturally available in almost every system. It is now suggested that a mechanism for producing appropriate nuclei exists in the crystallization of all but absolutely pure substances. Impurities can he of many kinds. Some will give rise to compounds that are less soluble in the solid crystal than in the liquid. A . crystal forming from a melt or solution containing these will be supersaturated in some degree, and the foreign atoms will commence to segregate during or after solidification. They do not necessarily form pure, unstrained, crystals of the precipitating compound with its normal composition and structure. Generally—at least in the metallurgical examples that have been most studied —the first recognizable nuclei have lattice coherency with the surrounding matrix and have practically the same crystal structure and lattice spacing as the material in which they form, differ- ing only in composition. An extremely thin oxide layer formed under appropriate conditions on or in a solid metal will tend to be coherent with the metal lattice, and the first few atom layers of the oxide in contact with the metal will differ in both composition and structure from massive crystalliue oxide. It will resemble the metal more closely than the oxide. If it did not subsequently change on melting, such an oxide film would constitute an almost perfect "template" or two-dimensional matrix to hold a few atoms of the primary metal in the exact array needed to form a nucleus for solidification. Any precipitating material will adopt the correct spacing over a few atom diameters, and with appropriate substitution of other atoms of the correct sizes a precipitate can match the parent lattice over large areas of cohererlce without excessive strain. In metals, the componentsof a host of oxides, silicides, borides, nitrides, carbides, sulphides, and other compounds are always present in minute amounts. Some of these will be eliminated because of extreme insolubility in the liquid, while others will remain soluble in the solid; occasionally, however, particles will be formed in the solid by coherent precipitation—not of pure substances, but of whatever assortment of atoms best satisfies the joint requirements of availability, affinity, and appropriate average atom size. Of these, many will disappear on melting, but a few will persist unmelted as little rafts of complex composition, maintaining in the liquid a surface of the exact geometry needed to nucleate the solid on subsequent cooling. Their number and size distribution will determine the resulting grain size; the dimensions of the largest will determine the degree of undercooling that can occur before solidification commences. A similar process may operate in the case of phase transformations in solids. The coherent precipitation of supersaturated minor constituents in a low-temperature phase should facilitate the nucleation of this phase on subsequent cooling after transforming into another phase at higher temperatures. At first sight this hypothesis may seem little different from the older ones. It should therefore be emphasized that it does not depend on chance to provide the right compound to form a nucleus, but postulates that every crystal, containing minute amourlts of any of a wide range of impurities, automatically engenders particles having the correct surface structure to serve as nuclei for subsequent solidification. It could operate in any system, metallic, organic, or inorganic. The suggested mechanism is closely analogous to the production of antibodies from antigens in living organisms—indeed, it was a description of the matrix theory of this process that suggested to the writer its crystalline analogue.

Jan 1, 1950

By M. M. Fidlar, Ralph E. Esarey

A marked decrease in drilling during 1937 in Indiana seemed to have no undesirable effect upon the oil and gas industry. Instead, production figures for oil showed a small increase over those for the preceding year, although not so much gas was marketed as in 1936. Drilling activity was centered in proven areas, and the proportion of dry holes to the number of wells drilled decreased somewhat. During 1937, including old wells drilled to deeper horizons, 134 wells were completed in Indiana, of which 39 were oil wells, 39 gas wells, and 56 dry holes. Nearly 75 per cent of the holes were drilled in proven areas. Of the 36 wells drilled in wildcat areas, only four found commercial production. Wildcat wells were especially numerous in Vigo, Pike, Perry and Spencer Counties. Exploratory drilling activity in Vigo County resulted in part from the drilling of the discovery well in the new Prairie Creek field. In Pike County, wildcat wells were drilled in the search for new supplies of gas to meet the demand in the southwestern portion of Indiana. Drilling in both proven and wildcat areas in Perry and Spencer Counties continued to be heavy, because of the presence of shallow Missis-sippian sands and the resulting low cost of drilling and equipping. At the end of the year, 42 of the wells started in 1937 were not completed. Only a few locations were drilled in the old Trenton field, but the wells, many of them 40 years old, continued to furnish a small supply of gas for domestic consumption. Oil production in the Jay County portion of the Trenton area was nearly twice that of 1936, owing in part to a vacuum system installed on several leases. The Harrison County (Laconia) gas field is being developed northward to offset water encroaching from the south. This water in the black shale threatens to put an end to the steady production that this field has furnished for many years. During 1937, the Oaktown gas field again furnished more gas than any other field, but production in that area showed a marked decrease over the marketed gas for 1936. During the early months of the year, seven wells were completed in the Oaktown field to bring the total number of producing wells to over 40. At present, all the operators in the area are

Jan 1, 1938

By R. A. McClelland

In the development of the Sirosmelt tin smelting process the need has arisen to understand and predict the problems likely to be encountered in optimal furnace operation on larger scales and over wide ranges of operating parameters. To study these parameters in detail with existing pilot plants and production scale plants is prohibitive in terms of cost, time and limitations of furnace design. The Sirosmelt computer model, SMELT, has been developed to simulate the process and to study a range of metallurgical parameters. The model's robust basic form has allowed adaption to a variety of needs. It is now being used to generate data on optimum operating conditions for a commercial scale plant and for operator training.

Jan 1, 1984

By Randolph Specht

A two year study was made of the waste disposal of the pebble rock phosphate industry. Solid slimes are impounded in large settling areas and the process water is re-used. Clear effluent was not found to be toxic to fish or animal life in field tests or in controlled experiments.

Jan 7, 1950

INTRODUCTION The mineral sample is the fundamental unit upon which the mineral appraisal is built. Values derived from the sample are the most important quantitative measurements made in the total evaluation process. The sample value

Jan 1, 1980

By Lewis Delano

IT HAS been generally recognized that, owing to the extreme friability of, galena, fine grinding has a tendency to cause excessive sliming of the mineral, so operators of lead mills have attempted to avoid this condition by commencing concentration at as coarse sizes as any mineral is freed. Jigging has been the basis of the milling process, making a clean coarse concentrate and a large amount of tailing, which was considered sufficiently low-grade to be rejected. However, developments and improvements in concentration processes are everywhere changing the low-grade tailing of yesterday into material worth retreating today. Investigations of the work of the Hancock jig on the Bonne Terre ore- have shown that the best results to be expected will give a tailing assaying 0.75 per cent. lead; the average over all conditions and grades of ore will be between .0.80 and 0.90 per cent. By crushing the jig tailings in ball-mills and retreating by tables and flotation, a tailing of considerably lower grade can be made; the problem then becomes an economic one of increased crushing costs versus higher recovery. In considering the entire elimination of jigging, the increased smelting charges; due to a greater amount of slime galena will be counterbalanced by the lower operating cost, in-creased recovery, and the many advantages of a simpler flow sheet. In developing these problems in the Bonne Terre mill of the' St. Joseph Lead Co., a long series of tests has been carried out covering every stage of crushing and concentration, and a large number of possible flow sheets were considered and tried. Only the final results and a few comparisons will be given here. At the same time, a careful and detailed cost-keeping system has enabled us to compare milling costs with the various flow sheets, and to calculate the economics of the problem' with great accuracy. .

Jan 8, 1920

Reynolds Jamaica Mines, Ltd., has received a $3+ million loan from ECA for the development of what are termed the largest bauxite deposits in the world in Jamaica, B.W.I. This amount is in addition to $11 million already provided. The new agreement calls for delivery of 750,000 tons a year beginning in early 1952. Inco has announced a new alloy containing 35 pet Ni which can be used for many purposes served by the old alloys which ran up to 70 pet Ni. The new alloy "Incoloy" is 35 pet Ni, 20 pet Cr, and the balance iron.

Jan 8, 1951

By C. E. Agnew

The Eastern district, composed of New Jersey and eastern Pennsylvania, with its native ores, was the cradle of the iron industry of the United States. The district attained and held the leadership in production of pig iron for over 100 years, from pre-Revolutionary days to approximately 1875. The first shipment of Lake hematite ore was made in 1853. It was a small shipment, transported by a sailing vessel and a canal barge, but it was the beginning of the end of the supremacy of the Eastern district, although at that time the ore was supposed to be too rich to be successfully smelted with the block coal then in use at western furnaces. The iron made from the first shipment of Lake ore was worked into nails by the Sharon Iron Co., at Sharon, Pa. The writer's great-grandfather, David Agnew, and his brother, John P. Agnew, owners and operators of the Sharpsville furnace, Sharpsville, Pa., worked the shipment through a furnace. Because of this, the writer feels some satisfaction in having been one of a group that solved the problem of making profitable an operation using Eastern district ores exclusively. With the development of Lake mines, and the production and use of coke, the Middle West district gradually assumed the position of leadership in production; because, even though the ores were transported 1000 miles by water and rail, its cost figure on pig iron was better than that of the eastern producer whose furnace was next to his mine. Such a cost figure was possible because the ore was naturally rich in iron and reduced easily. It was possible to carry a heavy burden on the furnace, which resulted in large tonnage and low coke per ton of iron. This paper is in no sense a technical one. The purpose is to show that with the proper physical preparation of the Eastern magnetites they will reduce as easily as the Lake hematites, and because of the high iron concentration give the Eastern producer just as much advantage as formerly he was at a disadvantage in comparison with the Middle West producer.

Jan 1, 1938

By C. E. Agnew

The Eastern district, composed of New Jersey and eastern Pennsylvania, with its native ores, was the cradle of the iron industry of the United States. The district attained and held the leadership in production of pig iron for over 100 years, from pre-Revolutionary days to approximately 1875. The first shipment of Lake hematite ore was made in 1853. It was a small shipment, transported by a sailing vessel and a canal barge, but it was the beginning of the end of the supremacy of the Eastern district, although at that time the ore was supposed to be too rich to be successfully smelted with the block coal then in use at western furnaces. The iron made from the first shipment of Lake ore was worked into nails by the Sharon Iron Co., at Sharon, Pa. The writer's great-grandfather, David Agnew, and his brother, John P. Agnew, owners and operators of the Sharpsville furnace, Sharpsville, Pa., worked the shipment through a furnace. Because of this, the writer feels some satisfaction in having been one of a group that solved the problem of making profitable an operation using Eastern district ores exclusively. With the development of Lake mines, and the production and use of coke, the Middle West district gradually assumed the position of leadership in production; because, even though the ores were transported 1000 miles by water and rail, its cost figure on pig iron was better than that of the eastern producer whose furnace was next to his mine. Such a cost figure was possible because the ore was naturally rich in iron and reduced easily. It was possible to carry a heavy burden on the furnace, which resulted in large tonnage and low coke per ton of iron. This paper is in no sense a technical one. The purpose is to show that with the proper physical preparation of the Eastern magnetites they will reduce as easily as the Lake hematites, and because of the high iron concentration give the Eastern producer just as much advantage as formerly he was at a disadvantage in comparison with the Middle West producer.

Jan 1, 1938

By H. T. Byck

THE plastering properties of six representative California drilling muds were studied over a temperature range of 70° to 175° F. at several mud weights, using a high-pressure circulating filter press with full size consolidated cores. In all tests, with untreated as well as with chemically treated muds, the filtration rates at elevated temperature were higher than at low temperatures and in nearly every case this increased filtration rate was notably larger than could be attributed alone to the decreased viscosity of water-the flowing medium-at elevated temperatures. It is concluded that no existing method will permit even an approxi-mate determination of the filtration rate at high temperature from data at room temperature. It is necessary to measure filtration at the tem-perature actually anticipated in the well, or to make a sufficient number of tests at various lower temperatures so that a small extrapolation of these data to the anticipated well temperature may be applied. Such tests should be carried out on the mud as actually used in the well. The viscosity of each of the muds was determined over the same temperature range. While no relationship was observed between mud viscosity and plastering properties, it was found that chemical treatment of the muds for viscosity reduction shifted the temperature of minimum viscosity to appreciably higher values than for untreated muds.

Jan 1, 1939

By Terry G. Richard, Sunder H. Advani

A sequence of 250 unconfined compression tests were completed on a common marine shale indicative of the overburden strata of east- central Ohio. The samples were of a light gray clay shale of Pennsylvanian age. The shales considered are obvious layered materials with distinct bedding planes. For this reason there is sufficient evidence to consider this material as anisotropic in nature. With a properly chosen reference coordinate system this anisotropy can be reduced to a layered orthotropic characterization. This implies that the mechanical properties can be specified with regard to principal material directions. With this nature in mind a systematic study of the combined influences of strain rate and moisture conditioning was initiated. Of particular interest is the variations in unconfined ultimate compressive strength with variations in the controlled parameters of strain rate, moisture conditioning level and direction of testing. Results of this particular phase of the program are presented.

Jan 1, 1982

By P. Barnes

If it be admitted that the use of the metric system of measurement is desirable, and that it will be well, as urged by one of our engineering societies, to show upon all our plans or drawings a metric scale in addition to a scale of inches, then it becomes important to introduce some ready means of drawing these scales. For many present purposes it is quite sufficient to space off and to draw them with the common dividers and the right-line pen, but if the number of drawings made or copied in an engineer's office, and upon which scales must be shown, is more than two or three daily, then some more mechanical or automatic means should be provided. For a great majority of detail drawings, a simple transcript of the surface of a good two-foot rule would answer every purpose, and probably the best comparative showing of the metric scale would be made by drawing a line of millimeters close by the side of the line of sixteenths. This would be in fact little more than the

By W. E. Newberry

The Aspen Mining District is situated at the eastern edge of the system of stratified rocks of western Colorado, where this edge meets the ridge of metamorphic granite which divides the State into two unequal parts. In following the valley of the Roaring Fork westward from the continental divide towards Aspen, one passes through a country of granite and gneiss, with no sedimentary rocks until the town is nearly reached. At this point the Cambrian quartzites first make their appearance, lying on the granites, with a dip of from 30' to 45 to the northwest. Beyond these quartzites and conformably upon them lie dolomites, limestones, shales, porphyries and sandstones, gradually flattening in general dip as one proceeds westward, but much disturbed by local foldings and faultings.

Jan 1, 1890

Future of State and Federal Oil Regulation. BY NORTHCUTT ELY (Trans , vol 118 2400 words) The Interstate Oil Compact, ratified by six states and Congress in 1935, replaced the petroleum code, invalidated with other codes by the Schechter decision This compact endeavors, first, to conserve reservoir energy of oil pools through substantially uniform conservation measures by the states, second, it recognizes the state rather than the Federal Government as possessing the necessary police power for that purpose, third, it establishes an interstate advisory commission, so that orderly production in one state is not penalized by uncontrolled production in another, fourth, Federal interests are recognized in the control of hot oil, regulation of imports and fact-finding forecasts of supply and demand by the Bureau of Mmes It is not as complete an instrument as proposed by the Federal Oil Conservation Board in 1932, but is workable, and will be effective in proportion to the support given it by the industry Three results may follow First, now that fear of Federal control has subsided, the industry may lose interest in the compact and let it fall to pieces, second, if vigorously supported by the industry, the compact can accomplish most of the conservation objectives sought by the Federal control measures now believed unconstitutional, third, if the Compact fails, Federal regulation is almost certain to be revived, and can probably be sustained in connection with neutrality legislation, regulation of interstate pipe lines, and coordination of Federal and state gasoline taxes Nearly every step toward governmental regulation has originated within the industry state proration, the Federal petroleum code, Federal control of imports, Federal control of hot oil are examples The Compact shows a trend toward coordination between the powers of the industry, the state government, and the Federal Government If this arrangement fails through lack of interest by the oil industry, the next step is likely to be absorption by the Federal Government of the other two factors involved in the situation

Jan 1, 1937

By J. R. Guard

Development of electrical power in coal mining has been an outstanding example of adaptbility. It has accommodated itself to new inventions, changing mining methods, increasing demands, increasing safety requirements and many other new conditions. With the appearance of the continuous miner in the mining machinery picture, those engineers interested in the application of electricity to mining have been thinking about what new comination of electrical apparatus will best suit this newcomer. It is the purpose of this paper to discuss the relative costs of supplying d-c versus a-c power to mining equipment with particular reference to continuous miner setups. Assume that a-c power will be delivered to the mine at some high voltage suitable for transmision to the various substation locations. Typical voltage for this purpose is 4000 volts. The problem then is to change the power to some kind of power suitable for driving the motors of mining equipment. For safety and other reasons the voltage to be delivered to the motor terminals must be under 600 volts.

Jan 6, 1950

By Waldemar Lindgren

I. INTRODUCTION AT the time of the discovery of America the old world had a scant supply-of the precious metals. Both the northern and the southern part of the new continent proved wonderfully rich in gold and silver and its treasures were eagerly looted; though the looting has lasted four centuries, the nines of its mountain chains are far from being exhausted. Even the later discoveries in Australasia and eastern Siberia could not rob the Western Hemisphere of its position as the greatest gold and silver producing region of the world, though finally the developments in a narrow and circumscribed area in South Africa wrested from the Americas their supremacy in the production of gold. Nevertheless the history of the two parts of the great western continent has been strikingly different. At first the Spaniards extracted vast treasures of silver from Mexico, Peru, and Bolivia, while Colombia and some placer deposits in Peru yielded a smaller quantity of gold. A couple of centuries later, a stream of gold began to flow from Brazil, the silver production from the countries mentioned above continuing strong in the meanwhile. Later on, the yield of South America diminished, but to offset this there began a wonderful series of discoveries in North America. The gold fields of California astonished the world; and when the cream of these had been skimmed off there began a no less amazing development of the Central Cordilleran gold and silver districts, which soon wade the United States the greatest producer of the precious metals. Aided by ever improving technique, extensive exploration, and a system of railroads, the yield was maintained and increased. Still later followed the discoveries of the gold fields of the arctic region and silenced those who had maintained that the zenith in gold production had passed. Recently the province of Ontario in eastern Canada

Jan 4, 1916

By Charles A. Ashburner

The existence of natural gas-springs in Pennsylvania and the adjoining States west of the crest of the Allegheny Mountains was known to the earliest settlers. Possibly the first gas obtained from a well was at Fredonia, Chautauqua County, N. Y., where a well was sunk on the bank of Canadaway Creek, near the Main Street bridge, in 1821, and sufficient gas obtained for 30 burners, the inn having been illuminated by the gas when General Lafayette passed through the village about 1821. In 1858 another well was drilled, which supplied 200 burners. A still larger one was drilled to a depth of 1200 feet in 1871. According to Mr. E. J. Crissey, Secretary of the Fredonia Natural Gas Light Company, the average monthly supply of these wells in 1880 was 110,000 cubic feet. Since 1859, when the drilling of oil-wells in Western Pennsyl-

Jan 1, 1886

By N. Brown, J. Washburn, E. R. Parker

MOST previous quantitative work on creep of single crystals has been concerned primarily with developing empirical equations for the creep curve. Although the equations used by Cottrell and Aytekin¹ and Tyndall² represented the data quite well, it was often necessary to use different values of the constants for different specimens even though they were apparently tested under identical conditions. In the course of previous work on the effect of surface coatings on creep of zinc single crystals," it was found that equal resolved shear stress frequently did not produce equal creep rates in different specimens. The work of Chalmers' in the very

Jan 1, 1954

By H. R. Tunnell

EVERY ONE connected with a mine knows that it is hard to keep down the costs of moving ore from the place where it is broken to the shaft or portal. Considered broadly, the subject of handling would cover all work done in a mine, but here it has been limited to handling ore in stopes and drifts, through chutes, and on levels. Good Ventilation and a strict enforcement of rules for the prevention of dust safeguard the health of the men and lower transportation costs. HANDLING ORE IN STOPES AND DRIFTS The object of all stoping is to mine ore of good grade at low cost. In Butte, the major part of the ore is mined, from Veins dipping from 60° to the horizontal to those which are vertical, by means of, square-set, rill, -timbered-rill, and back-filling stopes. When blasted, a part of the rock is carried by gravity to the grizzlies over the chutes, the rest is shoveled. Rock, when broken in a stope, may be deflected by inclined floors or slides toward the top of a chute leading to the level below. Ore broken clean enough to ship should be carried, by the force of its fall, into a chute or as nearly into that chute as the safety of the stope and the men permits. Ore that requires sorting, about 80 per cent. of all ore mined, is caught on a grizzly and the waste picked out. Waste rock broken in a stope is used to fill that stope and should be blasted into the gob with as little handling as possible.

Jan 2, 1922

By P. I. Brooker

The semi-variogram, the basic tool of geostatistical estimation procedures, must itself be estimated from the available data. From a numerically simulated two-dimensional deposit, with known variability expressed through its semi-variogram, the standard arithmetic mean estimator is used to calculate experimental semi-variograms. These are determined on a series of data sets obtained from the deposit with various sampling grids that cover different areas of the deposit and have a mite range in the number of available data. The orders of discrepancies between estimated and theoretical semi-variograms are determined in this idealized situation; and this provides a basis against which to assess experimental semi-variograms made on field data.

Jan 1, 1984