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By A. M. Kivari

OPERATIONS at the cement plant of the Permanente Corporation, in the hills about 45 miles south of San Francisco and 12 miles west of San Jose, are interesting to the members because of the adoption of modern hydrometallurgical methods for handling and beneficiating raw materials. Closed-circuit grinding, classification, hydro-separation, flotation, agitation, and thickening are familiar terms at this cement plant. These methods make it possible to process refractory limestone into suitable materials for the manufacture of modern cements. Construction of the plant, having originally a design capacity of 7000 bbl. of cement per day, was started in June 1939, and the first clinker was ground on the following Christmas Day. At present the capacity is about 12,000 bbl. of finished cement per 24 hr., most of the production being low-heat cement.† About 3130 tons of limestone, 620 tons 0f clay and 100 tons of gypsum are required daily for this output. Occasionally iron oxide is added to the clay to obtain the desired composition. This, together with the gypsum, is purchased from outside sources. Up to the present time, the corporation has produced low-heat, normal, moderate heat, moderate-sulphate-resisting, high-early-strength, oil-well, modified-oil-well, and plastic cements. Most of the present production is for Shasta Dam, near Redding, Calif., the total demand being 5,800,000 bbl, of cement. Following are some of the cement requirements of the Shasta Dam specifications: [PERCENT Chemical composition: Loss in ignition2.25 Insoluble residue0.75 SO32.25 MgO5.00 Uncombined lime in clinker (CaO)1 .25 Percentage of iron oxide to alumina ratio1.5 Compound composition: Tricalcium silicate (3CaO.Si02)Not more than 3,5 Dicalcium silicate (2CaO.Si02)Not less than 40 and not more than 65 Tricalcium aluminate (3CaO.Al2O7)Not more than 7 Tetracalcium aluminoferrite (4CaO.A12O3.Fe203) Not more than 0 Fineness:] The average specific surface in the bin sampled shall be not less than 1800 sq. cm. per gram and no individual sample less than 1600 sq. centimeters. Compressive strength: The average compressive strength-in pounds per square inch of three mortar cubes composed of one part cement and 2.75 parts fine testing sand, by weight, shall be equal to or greater than the following:

Jan 1, 1941

By Nicholas J. Grant, Noboru Komatsu

Metallographic and X-ray studies were made of oxide dispersion strengthened Cu-12 vol pet SiO2 and Cu-3.5 vol pet Al2O3 alloys following time exposures at temperatures approaching the melting. point of the matrix metal. Changes in hardness, oxide particle size and crystal structure were studied to determine the time-temperature stability of these alloys. An interpretation of the mechanism of oxide agglomeration is proposed. One of the most striking features of dispersion strengthened metal-metal oxide alloys is their stability at elevated temperatures, both with respect to recrystallization and maintenance of mechanical properties after exposure at high temperatures. A small amount of work has been done on the re-crystallization phenomenon in dispersion hardened metal-metal oxide alloys'l and several theoretical treatments have been advanced regarding the stability of these alloys by Lenel and Ansell,8 and by Grant and his co-workers.9, 10 This paper reports on metallographic and X-ray studies following various heat treatments of Cu-AI2D3 and Cu-SiO2 alloys at elevated temperatures and the effect of subsequent cold work on the recrystallizalion temperature. An interpretation of the recrystallization behavior of this type of alloy, based on the decomposition and agglomeration of oxides, is proposed. EXPERIMENTAL PROCEDURE Cast ingot bars of copper-1.59 pet Si and Cu-0.77 pet Al, 7/8 in in diam, were annealed in argon for 80 hr at 1000CC for homogenization. The homogenized rods were machined into fine chips and ball milled. Milled particles in the range minus 20 to plus 60 mesh were separated for internal oxidation. The internal oxidation was accomplished by the same method used by Preston and Grant,9 except that the oxidalion temperature for the Cu-Si alloy was 750°C, and for the Cu-A1 alloy was 800°C. These powders were then hydrogen-reduced at 450°C, compacted in a copper container, evacuated at room temperature to 0.04 µ, and sealed for extrusion. They were extruded at 1400°F (760°C) with a ram speed of 55 in. per min for an extrusion ratio of 15.6 to 1 to give a rod 0.38 in. diam by about 3 ft long.

Jan 1, 1962

By C. C. Bailey

THE vendor seeking outside capital for his project has the following potential sources which may be approached; 1--private sources, 2-institutional funds, 3--government agencies, 4--established mining concerns, and 5-public financing.

Jan 7, 1953

By Thomas Clagett

THE Pocahontas coal field comprises the area in Tazewell County, Va., and Mercer and McDowell Counties, W. Va., in which Nos. 3 and 4 Pocahontas seams of bituminous coal are mined. It is a mountainous region with ridges rising 300 to 1000 ft. (91 to 305m.) above the very narrow valleys and, except for some poorly kept farms along the tops of the ridges and the area occupied by the mining and coking plants and villages, is wooded throughout. First shipments were made from Pocahontas in 1883. There are now, about 100 mines, 95 per cent. of which are drift mines. At the end of 1920, approximately 298,000,000 gross tons of coal had been produced and 35,000 acres of coal mined. No. 3 seam is from 4 to 10 ft. (1.2 to 3 m.) thick, but the change is gradual and the thickness fairly uniform in any particular locality. It has a streak of bone, about 2 in. (5 cm.) thick, io which the coal adheres on both sides. In parts of the field this bone is replaced by hard slate, usually from 2 to 4 in. thick. The seam has a slate or fireclay bottom and a draw-slate top. No. 4 seam is from 65 to 80 ft. (19.8 to 24 m.) above No. 3 seam, and of minable section only in the western part of the field. It is from 3 to 8 ft. thick and has two streaks off bone, each from 1 to 2 in. thick. It has a fireclay or slate bottom and is overlaid by from 4 to 24 in. of a laminated coal and slate, locally termed "black rash," which is separated from the coal seam by about 3 in. of slate. This "black rash" averages about 25 per cent. ash, but contains some clean coal. The coal in both seams is quite soft. Cleavage sufficiently well defined to exert an influence on the mining is rare. Overlying strata are slates, shales, and sandstones, the sandstones predominating, extending from .30 to 1000 ft. above No. 3 seam. The strata directly above the. draw slate of No. 3 seam, or "black rash" of No., 4 seam, and up to the first sandstone are usually slates or shales, about 10 ft. thick over the

Jan 5, 1922

[For the year ending February, 1936 PRESIDENT AND DIRECTOR HENBY A. BUEHLER3 ROLLA, Mo. PAST PRESIDENTS AND DIRECTORS FREDERICK M. BECKET1 NEW YORK, N. Y. HOWARD N. EAVENSON2 PITTSBURGH, PA.]

Jan 1, 1936

By E. S. Lenker, H. J. Van Hook

A complete swies of solid solutions has been found between the compounds InAs and GaAs Below the solidus. The melting relations determined by differential thermal and static quenching technzques, indicate that the liquidus and solidus are of the simple ascendant type. No evidence of unmixing of the homogeneous solid solutions was observed at sub-solidus temperatures. A quenching method for locnting the solidus, using X-ray diffraction techniques, is described in some detail. THE semi-conducting properties of compounds formed by various combinations of the less familiar intermetallic elements have created an increasing interest in the phase relations in systems involving these elements. The complete phase diagram of such a system, containing a compound of special interest, will often provide information as to the most favorable conditions for preparing large crystals from a melt, as well as specifying the temperature stability of the crystalline phase or phases produced. In view of the current importance of gallium arsenide in semiconductor research and of the structural similarities of indium arsenide, it was thought that the complete phase relations of the system InAs-GaAs should be investigated. Previous work on the system Ga-As by Koster and homa' and on In-As by Liu and peretti2 has shown that GaAs and InAs are the only compounds formed, having melting points of 1238° and 942°C, respectively. In a survey of various systems of elements from groups IIIb and Vb, spengler3 also re- Mines Ltd., for his continuing encouragement and for permission to publish the results of this work. ports complete miscibility of gallium, indium, and arsenic in the liquid state. In a partial investigation of the InAs-GaAs system, Woolley and smith4 found extensive solid solution throughout the alloy range. Their subsolidus work, however, was inconclusive at temperatures below 900" and they did not determine the liquidus relationships of the system. PRESENT INVESTIGATION The starting materials used were high-purity gallium, indium, and arsenic. The method of preparation of the compounds follows that devised by M. Shafer and is described in detail in a paper by Shafer and eiser.' The end-member compounds, GaAs and InAs, were first prepared by reaction of the elements in the desired proportions in evacuated silica glass vials. The vials were rotated in a furnace as the temperature was slowly raised to insure rapid and complete reaction at low temperatures. Thereafter the starting materials, GaAs and InAs, were melted by heating the sealed vials to 1300" and 1000°C, respectively; the vials in this case were filled as completely as possible to keep the vapor space small and thereby minimize the loss of arsenic to the vapor phase. Ten binary mixtures of these compounds were then prepared by reaction of the powdered material in the solid state just below solidus temperatures. At 900C preparations containing 3, 5, 8, 10, 25, 35, 50, and 75 mol pct GaAs were found to be single homogeneous phases, indicating a complete series of solid solutions between GaAs and InAs. Moreover, it was discovered that the homogeneity of any crystalline binary preparation could be very accurately checked by X-ray diffraction because of the large differences in unit cell dimensions of the end membe5s. The cubic lattice constant ofor GaAs is a = 5.652A and that of InAs is a = 6.061A

Jan 1, 1963

By G. S. Hume

IN. THE autumn of 1922, British Petroleums Ltd. found oil of 14° Baumé in a sand 17 ft. thick in its. No. 2 well at Wainwright, 120 miles southeast of Edmonton. This greatly encouraged drilling in the Wainwright-Irma area and this past summer several wells were started, three of which are now completed and the others still being drilled. Of the three completed, No. 4 British Petroleums contains oil; No. 3 British Petroleums gave a show of oil but so far has not given much hope, of becoming a commercial producer; and No. 1 Maple Leaf Co., as now finished, is a. gas well with a daily flow of gas of about 2,500,000 cu. ft. at a closed pressure of 700 lb. An oil sand is reported to have been encountered below the producing gas horizon in the Maple Leaf well but has not been tested. Operations on this well have been suspended for the winter. The Geological Survey of Canada this past summer undertook a geological investigation of this area with the object of defining the structures with which the oil and gas are associated. The structure underlying this portion of the plains was supposed to be a terrace with the western edge dipping into the Alberta syncline and with a monoclinal structure to the east. By accurate leveling on known geological horizons on this terrace, a number of gentle folds were located and -it is in these folds that the oil and gas are found. At the British Petroleums Nos. 2 and 4 oil wells, the western flank of the fold has a gentle dip of only a few feet to the mile to the southwest whereas the strata on the eastern flank dip to the northeast about 40 ft. in ½ mile, the strike of the fold being northwest and southeast. How far oil will be found down the gentle southwest dip is unknown but probably the productive part of the fold will not exceed 1 mile in width, and possibly less. No. 3 British Petroleums well is on the strike of the fold 1 mile southeast of the two oil wells. The sand that was productive in Nos. 2 and 4 wells was not present in this well or, if present, was very thin and unproductive. Two other sand horizons, however, were encountered. The upper of these

Jan 3, 1925

By Oliver Smalley

EXCEPT for the work of Guillet, who conducted a systematic investigation on the zinc-replacing value of nickel in brass, and extended his investigation with a view to developing commercial high zinc content nickel brasses, the author does not know of any systematic research on the subject. The most promising commercial alloys and their physical properties obtained by Guillet are given below: Maximum Elonga- Reduction Copper Zinc Nickel Stress, tion, of Area, Brinell Tons Per Per Cent. Per Cent. Sq. In. 55.0 41.0 5.0 24.4 46.5 94 Sand cast. 22.6 27.0 90 Chill cast. 56.7 39.74 3.35 30.0 43.0 51.7 97 Casting annealed 2 hr. at 750° C. 33.9 33.0 50.7 144 Cold-drawn bar. 55.15 42.3 2.24 29.8 33.0 116 Casting annealed 2 hr. at 750° C. 32.3 29.0 151 Cold-drawn bar. These test results scarcely justify the use of such quantities of so expensive a metal, and could have been obtained from ordinary commercial brass. For purposes of comparison, the physical properties of ordinary brasses, ranging from 70 per cent. to 50.1 per cent. Cu in both the cast and normalized1 conditions are included in Table 1. These incidentally furnish a useful standard of the properties of castings and of rolled, extruded and forged brass when correctly annealed. A close study of some of the well-known special brasses containing nickel reveals a series of alloys which bewilder by their complexity, and one can only hazard a guess at the function and commercial value of each of the many elements used.

Jan 10, 1925

By W. P. Lass

The purpose of this article is not only to describe the plant and method of cyaniding the Treadwell concentrates, but to present some of the results of the experimental work obtained in the past three years for the Alaska-Treadwell Qold Mining Co., at Douglas Island, Alaska, under the direction of F. W. Bradley, Consulting Engineer, and Robert A. Kinzie, General Superintendent, of the affiliated companies. At the time the experimental work was undertaken the concentrates were being shipped to the smeltery at Tacoma, Wash., and the cost for treatment of 3-oz. (gold) concentrates was $11.95 per ton, divided as follows : Smelting-charges,......... $4.00 Loading, freight, insurance, etc., . 2.89 Interest due to time loat in transit and in settlement,... 0.05 Loss due to settlement for 95 per cent. of the gold at $20 per ounce, 6.01 Total,...$11.95 From the experimental work described later, it was estimated that 96 per cent. extraction could be made by treatment on the ground, and that the cost, when treating 80 tons per day, would be $3.25 per ton, divided as follows : Per Day. Per Ton. Labor,. $86.16 $@.827 Chemicals,.76.60 0.960 Power and steam-heat,... 67.60 0.845 Marketing-, refining- and other charges, . 49.36 0.617 Totals,.. $2.59.72 $3.250 Adding to this total the 4 per cent. treatment-loss, which on 3-02. concentrates amounts to $2.48, gives a total cost of $5.13 per ton. Comparing this with $11.95, the cost when shipping to the smelter, leaves a net gain of $6.22 per ton by the local

Jan 1, 1912

By W. F. Holbrook, C. E. Wood, E. P. Barrett

THE high-frequency laboratory induction furnace with a rotating liquid crucible enables research workers to conduct certain investigations heretofore very difficult or impossible to realize because vessels are not obtainable that are capable of resisting the physical conditions or the chemical actions to which they are subjected. Applications for patents covering commercial uses of centrifugal liquid crucibles were filed in the United States in 1919,1 in France in 1925, in the United States and Germany in 1926,2 and in France in 1927.3 In 1928, Schuette and Maier,4 of the Bureau of Mines, reported the construction of a whirling table beneath a high-frequency induction furnace. SHAPE AND SIZE OF CENTRIFUGAL LIQUID CRUCIBLES When a vessel containing a liquid is rotated, the inner surface of the liquid takes the shape of a paraboloid under the simultaneous action of centrifugal force and gravity. The internal dimensions of the paraboloid rotating liquid crucible are governed by the diameter of the container and .its speed of rotation. Melted Wood's metal was poured into cylinders 2 1/2 in. in diameter, which were rotated at 180, 300, and 468 r.p.m. When the metal was solid, a slurry of plaster of Paris was added, and rotation continued until the plaster had set. Fig. 1, a photograph of sections of the cylinders, shows the effect of speed of rotation of the containers upon the shape of the inner surface of the rotating liquid crucibles. TYPES OF FURNACES Three types of high-frequency induction laboratory furnaces using liquid-metal crucibles were designed and constructed by the Blast

Jan 1, 1938

By Joseph Daniels

The Fritz Engineering Laboratory was built under the direction of John Fritz, and presented by him to the University. A view of the building, looking east, is shown in Fig. 1. The building was started in 1909, and completed in 1910, although all of the equipment was not placed until later. Mr. Fritz gave his personal attention to the details of construction and equipment, and it was his custom to drive over every day to the University from his home in Bethlehem and spend some hours watching the work, offering suggestions, making changes, and planning new work. The result is a building and an equipment which embody his practical ideas. The laboratory structure is of the steel mill-building type, of light-colored brick, 91 by 114 ft., of which a section is shown in Fig. 2 and the floor-plan in Fig. 3. The steel frame carries the roof and traveling crane-way. Ample light has been provided by numerous windows in the side and end walls, in the clerestory, and by a skylight 84 ft. long and 9 ft. wide in the north roof. The main aisle of the building is 49 ft. 2 in. between centers of crane-columns, and has a clear height of 40 ft. The remainder of the width is taken up by two side aisles, 18 ft. high. The laboratory consists of four sections: (1) A general testing-section containing the testing-machinery, a small machine shop, and an office; (2) a cement-testing room; (3) a room for making and storing concrete test-specimens; (4) a hydraulic section.

Jan 1, 1912

By R. M. Brick

AN increased demand for information in regard to the effect of gaseous elements in steel has accompanied the recognition of the importance of grain size. Attempts to correlate grain-size characteristics with gas con-tent, particularly oxygen in solution or in the form of included metallic oxides, have not been universally successful. Certain definite effects of dissolved gases are recognized; specifically, the role of hydrogen in causing internal cracks or "flakes" and that of nitrogen in preventing excessive grain growth of ferritic chromium steels. When irregular behavior or properties are found in a well-known steel and no definite cause for the abnormality may be assigned on the basis of chemical and metallographic tests, dissolved gases are frequently blamed as the culprits. The solubilities of hydrogen1 and nitrogen2 in pure liquid iron are known but of the ternary systems, iron-alloying element-gas, only the Fe-Si-N3 and Fe-Cr-N systems have received attention and here the study was confined to liquid alloys. Krivobok4 published a curve show-ing the solubility of nitrogen in liquid Fe-Cr alloys but gave no informa-tion on the experimental procedure employed. The considerable experimental work reported on the Cr-N binary alloys has been reviewed by Hansen.5 It is generally agreed that the nitride CrN is a stable phase although the existence of nitrides within limited temperature ranges of stability, viz., Cr3N2 and Cr2N, has been disputed, Adcock6 and others7 have reported a eutectic between Cr and CrN at 1580°C., although the supporting evidence is not complete.

Jan 1, 1940

By William Fink

THE investigation of the phase relations of high-purity aluminum-base alloys is a part of the fundamental research program of the laboratories of the Aluminum Company of America. The results of a number of binary and ternary systems have previously been published in the transactions of this society. The aluminum end of the binary aluminum-titanium system has been studied. This system has received relatively little attention. To the authors' knowledge, there are two previous papers on this subject. E. van Erckelens1 determined the constitutional diagram reproduced in Fig. 1. .According, to this diagram, the liquids represents the separation of TiAl4 (Ti = 30.7 per cent.). He concluded that this is the composition of the compound, because in his work the eutectic horizontal terminated at 30.7 per cent. titanium and the metallographic examination of a sample of this composition revealed only one phase. According to the constitutional diagram developed by W. Manchot and A. Leber,2 reproduced in Fig. 2 from data given in their article, the liquidus represents the separation of the compound TiAl3 (Ti = 37.2 per cent. ). The composition of the compound was derived in a manner similar to that utilized by van Erckelens. Moreover, Manchot and Leber confirmed the composition of the compound by analysis of the constituent left as a residue after dissolving the alloys in weak sodium hydroxide solution. Although these are the only publications describing the constitution of the system, other investigators have studied the composition of the titanium compound. L. Wöhler3 says that there is a compound TiAl3 which was later confirmed by W. Manchot and P. Richter4 and by

Jan 1, 1931

By W. F. Holbrook, C. E. Wood, E. P. Barrett

The high-frequency laboratory induction furnace with a rotating liquid crucible enables research workers to conduct certain investigations heretofore very difficult or impossible to realize because vessels are not obtainable that are capable of resisting the physical conditions or the chemical actions to which they are subjected. Applications for patents covering commercial uses of centrifugal liquid crucibles were filed in the United States in 1919,' in France in 1925, in the United States and Germany in 1926,2 and in France in 1927.3 In 1928, Schuette and Maier,4 of the Bureau of Mines, reported the construction of a whirling table beneath a high-frequency induction furnace. Shape and Size of Centrifugal Liquid Crucibles When a vessel containing a liquid is rotated, the inner surface of the liquid takes the shape of a paraboloid under the simultaneous action of centrifugal force and gravity. The internal dimensions of the paraboloid rotating liquid crucible are governed by the diameter of the container and its speed of rotation. Melted Wood's metal was poured into cylinders 2 1/2 in. in diameter, which were rotated at 180, 300, and 468 r.p.m. When the metal was solid, a slurry of plaster of Paris was added, and rotation continued until the plaster had set. Fig. 1, a photograph of sections of the cylinders, shows the effect of speed of rotation of the containers upon the shape of the inner surface of the rotating liquid crucibles. Types of Furnaces Three types of high-frequency induction laboratory furnaces using liquid-metal crucibles were designed and constructed by the Blast

Jan 1, 1939

By W. F. Holbrook, C. E. Wood, E. P. Barrett

The high-frequency laboratory induction furnace with a rotating liquid crucible enables research workers to conduct certain investigations heretofore very difficult or impossible to realize because vessels are not obtainable that are capable of resisting the physical conditions or the chemical actions to which they are subjected. Applications for patents covering commercial uses of centrifugal liquid crucibles were filed in the United States in 1919,' in France in 1925, in the United States and Germany in 1926,2 and in France in 1927.3 In 1928, Schuette and Maier,4 of the Bureau of Mines, reported the construction of a whirling table beneath a high-frequency induction furnace. Shape and Size of Centrifugal Liquid Crucibles When a vessel containing a liquid is rotated, the inner surface of the liquid takes the shape of a paraboloid under the simultaneous action of centrifugal force and gravity. The internal dimensions of the paraboloid rotating liquid crucible are governed by the diameter of the container and its speed of rotation. Melted Wood's metal was poured into cylinders 2 1/2 in. in diameter, which were rotated at 180, 300, and 468 r.p.m. When the metal was solid, a slurry of plaster of Paris was added, and rotation continued until the plaster had set. Fig. 1, a photograph of sections of the cylinders, shows the effect of speed of rotation of the containers upon the shape of the inner surface of the rotating liquid crucibles. Types of Furnaces Three types of high-frequency induction laboratory furnaces using liquid-metal crucibles were designed and constructed by the Blast

Jan 1, 1939

By E. Teghtsoonian, A. R. Causey

THE fact that the surface plays an important role in the plastic deformation of a single crystal has been demonstrated by several investigators. The surface conditions have been altered using oxide films,1'2 alloyed metal layers,3, 4 deposited metal films,' and polycrystalline layers.677° The resulting effects on the initiation and subsequent plastic deformation have been investigated extensively except for the case of a single crystal surrounded by a polycrystalline layer of the same material. The purpose of this paper is to describe an investigation of the effect of a polycrystalline surface layer on the yield stress, the critical resolved shear stress, and the work-hardening slope of tin single crystals. The tin single crystals used in this study were grown from the melt using material having an initial purity of approximately 99.999 + pet with lead and iron the major impurities. Fig. 1 shows the orientation of the (110)[001] slip system with respect to the crystal surfaces. The crystals had a 1/4 by 1/4 in. cross section and a gage length of 2 in. The polycrystalline surface layer was produced by abrading the single-crystal specimens with emery paper. Fig. 2 shows the broken Debye rings obtained from the deformed surface. The thickness of the layer was controlled by the number of passes on different grades of paper and was determined by electropolishing in dilute HC1, until the grains produced by the abrasion had all been removed. Metal-lographic examination showed that the grain size varied with depth, increasing from 10 µ right at the surface to 40 µ in the interior of the layer. The yield stress, critical resolved shear stress,

Jan 1, 1965

By Harry Warren

THE Geology Department of the. University of British Columbia has undertaken the task of examining the ores from as many as possible of the gold mines of British Columbia. The object of this work is two-fold. First, it is known that detailed mineralographic studies are useful in attacking ore-dressing problems, and these studies are intended to be helpful to mill operators. Second, it is hoped that mineralogical and mineralographical studies will prove useful adjuncts to those of lithology and structure in throwing more light on problems related to the origin of the deposits. The paper shows that gold, for all practical purposes, is not present in an ore mineral in solid solution nor as a eutectic with any mineral; if the latter were true the gold particles would be distributed equally throughout that mineral. The gold occurs either as native gold or as a gold-silver telluride and is not distributed regularly through any mineral or minerals: The relationship between the gold or gold-bearing telluride and the associated minerals affords a means of classification that is not only simple but also appears to be directly related to the geological nature of the deposit, which may be summarized as follows: 1. Disseminated Gold Type. ;-Precious minerals in extremely small grains, which are distributed without regard to grain size, fractures or grain boundaries: (1) Hedley variety-gold in native form; (2) Surf Point variety-gold predominantly as telluride. 2. Veining Gold Type.-Precious minerals in grains of various sizes, which occur mainly along fractures and grain boundaries: (1) Cariboo gold quartz-gold in native form. (2) Waneta variety-gold as telluride.

Jan 1, 1937

By Michael Tenenbaum, T. L. Joseph

In a previous investigation1 the authors studied the effect of pressure on the reduction of iron ores by hydrogen. With hydrogen as a reducing agent, the rate of reduction was increased substantially by increasing the pressure from 1 to 2 atmospheres. The results with hydrogen prompted the present study of the effect of pressure on reduction with carbon monoxide and with mixtures of carbon monoxide and nitrogen. Features of Reduction Process The gas stream in the lower part of the blast furnace always contains sufficient concentrations of reducing gases to complete reduction provided sufficient time is allowed for the reaction to proceed. Reducing gases react immediately with the iron oxide on the surface of lumps of ore. However, as the unreduced surface recedes from the easily accessible exterior of the lump, the reaction proceeds by virtue of the diffusion of the gases into and out of individual pieces. The rate of diffusion of gases, which undoubtedly plays an important role in the reduction of iron ores, depends on several factors, most important of which are: (1) molecular weight or density, (2) pressure, (3) temperature, (4) concentration gradient. Thus, the rate of reduction of a lump of iron ore at any temperature will depend not only on the specific reaction rate but also upon: (1) available surface of unreduced iron oxide, (2) rate of diffusion of the reducing gas to the reacting surface, (3) rate of effusion of the gaseous products of the reaction from the reacting surface, (4) adsorption of the gases on the reacting surface. The various features of the reduction process were discussed in previous work and need not be reviewed. However, in order to explain

Jan 1, 1940

By Michael Tenenbaum, T. L. Joseph

In a previous investigation1 the authors studied the effect of pressure on the reduction of iron ores by hydrogen. With hydrogen as a reducing agent, the rate of reduction was increased substantially by increasing the pressure from 1 to 2 atmospheres. The results with hydrogen prompted the present study of the effect of pressure on reduction with carbon monoxide and with mixtures of carbon monoxide and nitrogen. Features of Reduction Process The gas stream in the lower part of the blast furnace always contains sufficient concentrations of reducing gases to complete reduction provided sufficient time is allowed for the reaction to proceed. Reducing gases react immediately with the iron oxide on the surface of lumps of ore. However, as the unreduced surface recedes from the easily accessible exterior of the lump, the reaction proceeds by virtue of the diffusion of the gases into and out of individual pieces. The rate of diffusion of gases, which undoubtedly plays an important role in the reduction of iron ores, depends on several factors, most important of which are: (1) molecular weight or density, (2) pressure, (3) temperature, (4) concentration gradient. Thus, the rate of reduction of a lump of iron ore at any temperature will depend not only on the specific reaction rate but also upon: (1) available surface of unreduced iron oxide, (2) rate of diffusion of the reducing gas to the reacting surface, (3) rate of effusion of the gaseous products of the reaction from the reacting surface, (4) adsorption of the gases on the reacting surface. The various features of the reduction process were discussed in previous work and need not be reviewed. However, in order to explain

Jan 1, 1940

By H. T. Clark

Within the last twenty years at least three sets of lattice constants for the room temperature (alpha, hexagonal close packed) phase of titanium have been reported in the literature. These values, summarized in Table 1, differ one from another by amounts far greater than can be explained on the basis of inaccuracies in parameter measurements. This paper presents new values determined for high purity titanium. It also details the effect of two elements, oxygen and nitrogen, on these parameters and shows that two of the previously reported values are probably in error because of the presence of one or both of these elements in the material used for examination. Preparation of Samples The titanium+ used for this study was prepared by the thermal decomposition of titanium tetraiodide7 on a hot titanium filament. This titanium rod was prepared for X ray examination by melting about 10 g in purified argon in an electric arc furnace on a cold hearth. This cast button was cold rolled to 0.040 in. thick sheet, cleaned, annealed in vacuum at 1000°C and cold rolled to 0.020 in. thickness. About 0.003 in. of surface material was then removed by hand grinding on papers to remove any contamination caused by the rolls and the sample was bent to the radius of the focusing camera. The sample was then vacuum annealed at 600°C, a temperature just high enough to cause recrystallization, producing a fine grained structure. Such a structure is essential in sheet specimens prepared for focusing cameras in order to have a sufficient quantity of grains to develop continuous diffraction lines. The use of sheet specimens rather than powder samples appears to be essential for the X ray examination of titanium. This is because of titanium's exceptionally high gettering power and its rapid absorption of adsorbed gases, water -vapor, and the like at annealing temperatures. While the effect of this contamination may be neglected for sheet specimens, its effect on 200-300 mesh powder is appreciable. Titanium alloys of oxygen and nitrogen were prepared by a technique simi- lar to that described above except that the required amount of the highest purity titanium oxide or nitride available was added prior to melting in the arc furnace. These materials were added by placing them in holes drilled in the titanium. A small weight loss invariably occurs during the melting of these oxygen and nitrogen alloys. This is believed to be due entirely to the loss of some of the powdered compound in the blast of the electric arc, an assumption which is justified on the basis that there is no weight loss during the melting of titanium metal and that wet analyses for nitrogen on representative samples have checked with the calculated analyses when it was assumed that the entire loss during melting was due to the loss of titanium nitride powder. These alloy buttons were reduced to sheet in the same manner as used for the unalloyed titanium. Experimental Procedure A North American Phillips 12 cm diam symmetrical precision focusing vacuum camera and copper radiation

Jan 1, 1950