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By William G. Fricke

MaCROSEGREGATION, as distinct from microseg-regation, is often inverse in nature. That is, the eu-tectic solute elements, which are expected to be con-

Jan 1, 1970

By Joseph Pogue

THE prices of crude petroleum and its derivatives have shown an upward trend from 1915 to 1920, and a downward trend from 1920 to 1923, see Table 1. Over the former period, oil prices were dominated by the rapidly increasing demands and inflation incident to the war and its aftermath, while over the latter period oil prices were influenced at the outset by deflation and then by the conditions of overproduction that have characterized the past three years. The purpose of this paper is to analyze the broader features of the more recent price movements in the petroleum industry and to relate these features to basic economic conditions in the industry.

Jan 3, 1924

By John J. Childress, Russell L. Cook

Stringent environmental regulations, which have limited the use of sludge ponds, coupled with the economic incentive to clean more coal or to add fine coal cleaning additions to existing preparation plants have increased the use of static thickeners in preparation plants. The Lamella Gravity Settler, sometimes designated Lamella Thickener, is a shallow depth sedimentation device which has been applied in a variety of industrial process and wastewater control projects in place of the conventional raked thickeners. This paper presents the theory and design of the Lamella Thickener, as well as describing the operating results from several full scale installations in a variety of Appalachian preparation plants.

Jan 1, 1979

By H. M. Howe

The tenacity with which a bad name adheres to a process is well illustrated by the prevalent belief in the irregularity of the product of the Bessemer converter. We have been lately told by an eloquent member that lack of uniformity is the name of Bessemer steel, and that uniform soft steel can only be made in the Clapp-Griffiths Bessemer converter. Yet I believe that, however irregular the percentage of carbon in Bessemer steel may have been formerly, to-day it is well-nigh completely under control. Indeed, the results of a large number of analyses that I' have studied go to show that the

Jan 1, 1887

By D. L. Wood

INTERNAL oxidation' is a process in which oxy-gen, diffused into a suitable alloy, causes precipitation of solute oxide particles as the oxidation front moves inward. During an investigation of internal oxidation now in progress it was observed that the grain size is relatively small in thin strip specimens that have been internally oxidized in the as-rolled condition. This may be due to the restraint of grain growth by the precipitated oxide particles. It was observed also that the grain size in unoxi-dized portions of partially oxidized specimens was

Jan 1, 1958

By J. B. Hiskey, G. Ramadorai

This paper presents the kinetics of leaching pure wulfenite (PbMoO,) with sodium sulfide solutions. Wulfenite dissolves in the presence of sulfide ion according to the following reaction: PbMoO , + S= PbS + MOO;. Synthetic galena is formed and molybdenum is released to solution as molybdate ion. The reaction follows the shrinking core model and the leaching mechanism involves mixed kinetics where both diffusion and chemical reaction are rate controlling. Molybdenum extraction is explained in terms of temperature, particle size, and sodium sulfide concentration.

Jan 1, 1977

By Robert Maddin, Neng-Kuan Chen

THE (001) planes have been reported as the cleavage planes in body-centered cubic metals such as alpha-iron and tungsten.' However, in molybdenum, which is also body-centered cubic, experimental X-ray evidence indicating a similar cleavage plane still seems lacking. Tsien and Chow" observed microscopically in the extension at around 1000°C of molybdenum single crystalline wires 0.25 mm in diam that the fracture plane seemed to be parallel to the operative slip plane, which appeared to be (110) at that temperature. Zapffe' pointed out from fractographic study of polycrystalline molybdenum that "although the transgranular pattern is characteristically non-crystallographic, patterns occasionally reveal {100} cleavage." This has been generally assumed to be the case at ordinary temperatures. In the present experiments, a single crystal of Fansteel molybdenum, Vs in. diam x 2 in. long, prepared by the methods described by Chen, Maddin, and Pond" was fractured at room temperature by bending. The fracture surface appeared to be quite similar to the cleavage surface of zinc and was crys-tallographic. A back-reflection Laue photogram was made using 35 kv copper white radiation; the X-ray

Jan 1, 1952

By Edward Halse

Normal banded structure,* exhibiting bands or layers of mineral symmetrically arranged from the sides to the center of the vein, appears to be by no means common in the Republic of Mexico. When the bands of quartz form interlocking crystals in the center (" comb-structure "), the evidence that the filling has taken place in an open space is complete. This also applies in the case of any mineral the fibers of which are perpendicular to the walls, and which presents here and there, in a central line, cavities or vugs lined with crystals (geodes); but it does not follow that the whole width of the banded vein represents that of the original open fissure. The opening and filling may have been slow and gradual processes, advancing

Jan 1, 1902

Jan 1, 1902

By Richard Hamburger

Calculating machines permit the use of the more rapid cotangent and semigraphic solutions of plane triangulation. The results of these methods are as accurate as those of other methods. Simple adjustment of the net, and ease of calculation encourage more complete field work. Errors in field work or in computation are easily localized.

Jan 2, 1950

By Albert R. Ledoux

With the improvements in design and efficiency of machinery the element of danger in its use is becoming less, but it is a question whether the strain involved in operating modern plants is not increasing somewhat the danger of accident due to human fallibility. I propose to describe a somewhat uncommon casualty resulting from a not infrequent incident in the use of air-compressors. It is not necessary to state the location of the mine in which the accident occurred nor the makers of the compreseor, and the object of this brief paper is more to draw out suggestions from members more familiar than am I with the practical handling of mining machinery, than to point a moral. The compressor in question was a three-drill machine of standard make. At the time of the accident it was furnishing air to a single drill working in an upraise from a well-ventilated tunnel, and giving ventilation to a winze below the tnnnel where two men were hand-drilling. The compressor also furnished power to a small hoist in the winze, but the hoist was only operated occasionally, and never while the drills were working. The drills were located about 1200 ft. from the compressor. The engineer testified that he never had been short of air, and that there had been no complaillts that the

Jan 1, 1904

By Walter Harvey Weed

(Mexican Meeting, November, 1901.) Among the many causes of that perplexing featurc of mineexploitation, the unequal distribution of the ore, the influence of the country-rock upon the vein-contents has long beer1 accepted as an important factor in certain districts, but the general application of the theory has not been proved. It is now possible to obtain trustworthy data with which to test the theory, and either to confirm or to overthrow this time-honored

Jan 1, 1902

H. 0. HOFMAN, Boston, Mass (written discussion*).-The paper by Mr.. Pyne gives clear evidence of the difficulties the metallurgist is likely to encounter when he tries to recover in the blast furnace the metal from old chromite lining used as a refractory material in the copper reverberatory furnace. It appears that chromite cannot be fluxed at temperatures which usually prevail in copper blast furnaces. This calls to mind the freezing-point curve drawn by M. Simonis1 of mixtures of chromite and kaolinite. The chromite used in the experiments contained 52.9 per cent. Cr203, 22.6 FeO, 4.8 AI203, 9.6 Si02, .10.1-MgO; FIG. 1. the kaolinite was clay from Zettlitz with 98.5 per cent. clay-substance: The accompanying curve shows that the eutectic mixture with 35 per cent. kaolinite and 65 per cent. chromite freezes at Seger cone No. 15 (1435° C.), while kaolinite fuses at cone No. 35 (1770° C.) and chromite at cone No. 42 (2000° C.). The curve indicates that the difficulty in the blast furnace can be overcome by having at the smelting zone a temperature much higher than is usual in copper smelting; a charge composition similar to that prevailing at the Mansfeld copper smeltery -which gives with 23 per cent. coke a, slag of the composition Si02, .49.09; .(FeMg)0, 5.58; (CaMg)0, 16.02; A1203,-16.02-might flux and fuse chromite.

Jan 3, 1918

Conquista, the uranium mining and milling complex owned jointly by Continental Oil Co. and Pioneer Nuclear, Inc., has begun operations in Falls City, Texas. The mill has been designed to produce 1.5 million lb of U3O, from 600,000 tpy of ore mined. Currently, the plant processes a maximum 2000 tpd of ore. Mine Planning Texas ore deposits are small and scattered in comparison to other uranium mining districts. Those to be mined at Conquista range from a few acres to more than 100 acres in size. Ore thickness ranges from a few inches to over 15 ft, and depth from less than 20 ft to more than 170 ft below ground surface. Distance from the mill ranges up to 35 mi.

Jan 8, 1972

By J. W. Harden

THE observations here following are the result of an examination made as to the feasibility of extending the South Mountain Railroad from Pine Grove to Waynesborough, and of the commercial value of the ore through which such extension would be made to pass. The road at present built and in operation has a junction with the Cumberland Valley Railroad, half a mile east of Carlisle, and extends southward to Pine Grove, a distance of 176 miles. The extension proposed will add to it near 27 miles, making its total length 44$, more than 23 of which will run through, or in close proximity to, beds of ore. Along the route taken there are a number of openings at which the ore is gotten, of which the Craighead bank, Huntzinger's bank, Lowrey's bank, Wenkoop's bank, the Henry Clay bank, the Fuller

Jan 1, 1904

By Jerome S. Nelson, William S. Johnson

Seismic investigations at pre-construction sites commonly are limited to obtaining velocities and thicknesses of subsurface intervals which are useful in estimating construction costs, but are sometimes difficult to apply to project designing. This paper shows through a case history of the San Bernardino Tunnel Intake Tower, a part of the California State Water Project, that dynamic rock properties and dynamic resonant frequencies can be determined and velocity models constructed from in situ field studies and that these are theoretically correct after simplifying assumptions are made. These data can be used to confirm and extend information obtained by conventional methods such as drilling and laboratory static testing.

Jan 1, 1971

By C. H. Li, R. J. Stokes, T. L. Johnston

Sodium chloride crystals are brittle in the presence of surface microcracks. Water immersion leads to an enhancement of ductility which is retained indefinitely in dry air providing the crystal is dried without leaving a surface precipitate. Storage in a damp atmosphere results in a surface reaction and consequent rembrittlement. Although elimination of surface flaws in ionic solids does not necessarily enhance ductility, there is always a change in the location of the fracture origin. EVER since the original experiments of Joffel there has been controversy over their interpretation and no satisfactory generalized explanation has yet been given. It is generally admitted that when sodium

Jan 1, 1961

By J. W. Harden

THE observations here following are the result of an examination made as to the feasibility of extending the South Mountain Railroad from Pine Grove to Waynesborough, and of the commercial value of the ore through which such extension would be made to pass. The road at present built and in operation has a junction with the Cumberland Valley Railroad, half a mile east of Carlisle, and extends southward to Pine Grove, a distance of 172 miles. The extension proposed will add to it near 27 miles, making its total length 442, more than 23 of which will run through, or in close proximity to, beds of ore. Along the route taken there are a number of openings at which the ore is gotten, of which the Craighead bank, Huntzinger's bank, Lowrey's bank, Wenkoop's bank, the Henry Clay bank, the Fuller

Jan 1, 1873

By R. W. Heckel, J. H. Smith, H. W. Paxton

The habit plane of proeutectoid cementute precipitated from austenite was studied using a two-trace surface (analysis coupled with a direct X-ray back-reflection determination of the orientatzon of the parent Matrix. The results were the same as those obtained by earlier workers1 - 2 who used Indirect methods to determine the orientation of the matrix. The data indicate that a range or habit planes in the parent phase is operative which is not in agreement with accepted existing theories. In 1933, Mehl, Barrett. and smith1 obtained a non-unique result in a study of the Widmanstätten habit plane of proeutectoid cementite. Their data are shown in Fig. 1. These results were verified by Greninger and Troiano,2 although they did not pre-sent any data. Both of these investigations relied upon indirect methods of determination of the matrix lattice orientation. Theoretical considerations of Widmanstatten precipitates have usually proved or assumed an orientation relationship between matrix and precipitate; the habit plane expressed relative to the matrix is generally unique, although it may be irrational.3 Opinion is divided as to the factors influencing the choice of habit plane. Mehl4 felt that a nucleus which was plate shaped to minimize strain energy and surface energy during its formation could maintain this shape by the point effect of diffusion; the

Jan 1, 1961