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By T. A. Read, H. M. Otte

THEORETICAL analysis by Wechsler, Lieberman and Read of the crystallography of martensite formation has shown that the requirement for the existence of a macroscopically undistorted plane between austenite and martensite permits a calculation of the indices of the habit plane of the marten-

Jan 1, 1958

By C. E. Lundin, D. T. Klodt

The binary alloy systems, Y-Ti, Y-Zr, and Y-Hf, have been investigated throughout their entire composition regions. There is no compound formation in any of the systems, and each system is characterized by a single eutectic reaction. The eutectic compositions and temperatures are as follows: A eutectoid reaction pct Y and 870°C occurs in the Y-Ti system, whereas a peritectoid reaction,: pct Y and 880°C occurs in the Y-Zr system. Peri-tectic-type reactions at temperatures above the eutectic levels are postulated for the yttrium and hafnium transfovmations. The development of the technology of yttrium has been given considerable attention during the past few years, and studies of binary phase equilibria have, of course, taken a prominent position in this development. In many respects yttrium, in the third group of metals of the periodic table, is similar to the adjacent group of metals, titanium, zirconium, and hafnium, and the knowledge of the phase relationships of yttrium with these metals is basic to their technology. MATERIALS AND EXPERIMENTAL PROCEDURES Materials. The metals for this investigation were supplied by the General Electric Co., Aircraft Nuclear Propulsion Department. The yttrium was in the form of an arc-melted ingot, and the other metals were in the form of high-purity, iodide-Process crystal bar. Table I lists the purities of these materials. Alloy Preparation. Melting was done by conventional techniques in a nonconsumable electrode arc furnace in an atmosphere of purified argon. Melting conditions for each binary system were the same. Each alloy button was inverted and remelted several times to assure homogeneity. Accurate weights of the charges and resultant alloy buttons were obtained to indicate deviations from intended compositions. No chemical analyses were obtained since melting weight losses were consistently in the range of 0.1 to 0.2 pct of the total weight. 10- or 20-g buttons for each 5.0 wt pct composition increment were melted to survey the three individual alloy systems. Additional alloys differing in composition by 1.0 or 0.1 wt pct increments were also melted to study selected regions of the systems. Metallograpllic Techniques. Standard metallo-graphic techniques were followed for mounting and rough grinding. Preliminary polishing was accomplished using 6-u diamond paste as an abrasive on a Metcloth Lap. Final polishing was done on a Microcloth-covered wheel using 1-u diamond abrasive paste. Purified kerosene was used as a lubricant for both polishing stages. • sothermal- Annealing. Alloys were sectioned for as-cast structlure examinations and then homogenized in preparation for isothermal-annealing treatments. Homo{:enization was accomplished by cold pressing the alloy buttons followed by 72-hr anneals at 1100c. The alloys were encapsulated in Vycor or quartz for the homogenization treatments or for isothermal anneals. Resistance-wound or resistance-element tube furnaces were used for the annealing treatments. The homogenized alloy buttons were cold rolled until cracking occurred or until a -in. specimen thickness was obtained. Small -in. square) specimens for the isothermal anneals were then sawed from the alloys. Each specimen was wrapped in tantalum foil before being sealed in the capsule. Temperatures during the anneals were controlled The time at temperature necessary to equilibrate the structures during the anneals was determined for each alloy system by holding triplicate specimens of alloys at a constant temperature for three different periotls. The specimens were quenched and examined microscopically to determine the number and amounts of phases present in the micro-structure as a function of time. Melting Studies. Eutectic temperatures of the three alloy systems were established from the results of incipient-melting studies conducted on as-cast alloys. Specimens to be melted were suspended on a tungsten wire inside a graphite cylinder placed in a glass vacuum chamber. An optical pyrometer was used to follow the temperature of the specimen as it was inductively heated in a high vacuum. The temperatures were corrected for emissivity losses by standardizing the pyrometer with known-melting-point metals. Accuracy of the temperature measurements is estimated to be + 10°C. The melting point of the yttrium was determined to be 1550°C by this technique. The invariant-temperature levels were also checked by an anneal-quench technique. This technique consists of annealing a series of

Jan 1, 1962

By B. Stimpson, D. M. Ross-Brown

Borehole information is often the only source of information on rock conditions at depth during the stage of feasibility studies of a project, and from this data the rock mechanics engineer would like to make some quantitative estimates of rock mass cohesive strength. While judgement and experience will usually play a paramount role at this stage, simple tools for estimating rock mass cohesive strength would be an asset. In this paper, an approximate technique is suggested for assessing the cohesive strength of a randomly jointed rock mass from borehole data on fracture intensity and intact rock strength.

Jan 2, 1979

By W. W. Anderson

A formula for quantitative efficiency is proposed, in which the efficiency value is a function of the improperly distributed material at the gravity of separation effected by the cleaning equipment. The misplaced material is expressed as a percentage of the total material discharged from the equipment. Numerous examples are given, demonstrating application of the formula to various types of separation, including multiple-product separations.

Jan 2, 1950

By Eckley B. Coxe

IN making surveys in the anthracite coal regions of Pennsylvania, the ordinary engineer's chain (50 or 100 feet long) is generally used, both above and below ground. Sometimes, where it is difficult to chain, as, for instance, across a chasm, a wire is stretched from one station to the other, the distance is marked on the wire and its length is then measured with the ordinary chain. Having had occasion lately to make some surveys where it was necessary to determine with great accuracy the position of the land or property line, not

Jan 1, 1874

By W. H. W. Husband

Rock salt has been solution mined for many years in many countries. Attempts have been made in the past in Canada and various other countries to produce potash by the same method. However, only Kalium Chemicals Ltd. has been successful, possibly because the conditions in Saskatchewan are the most favorable to be found so far for the development of a solution-mining method for potash. In view of the fact that few studies of solution mining of potash have been attempted, only one company has succeeded in using the method, and no information has been released by this company, the application of solution mining of potash ore bodies has to be presented on the basis of available theory, past small-scale studies, and recent patents. A simple mining method is outlined and possible methods of recovering the potash from the brine are discussed. Dissolution data pertaining to solution mining of potash, flowsheets, and material balances are presented. The available information is brought together in a cost analysis to show capital and product costs in terms of 1966 dollars.

Jan 1, 1972

By E. A. Lowe, C. C. Walden, D. W. Duncan, P. C. Trussell

The industrial importance of bacteriological leaching is finding increasing application in the treatment of low-grade ore and of exhausted mines. Another possible application of bio-leaching is in the extraction of ore concentrates, although here the first uses will likely be for ores that are refractory to conventional metallurgy. Biological leaching studies, which have been in progress for over ten years in this laboratory, are directed towards the more rapid and complete leaching of metals from their sulfides, particularly of copper, zinc, and nickel. The program involves not only laboratory studies, but pilot-plant operations and liaison with mining companies which are underwriting the cost of the investigations. Although the bacterial oxidation of mineral sulfides to the corresponding water-soluble sulfates has been occurring naturally for many centuries, the first documented recovery of solubilized metal from pregnant solution was at the Rio Tinto operation in Spain. At this location leaching variables were studied extensively in an empirical manner some years before the causative bacteria were first isolated from other leaching situations. Documentation of the presence of bacteria in leach waters of the Rio Tinto, Spain, operation was not confirmed until 1962.3 On this continent leaching was pioneered in the early

Jan 1, 1968

By Timothy E. LaTour, Robert Kerrich

Microstructures and mineral chemistry of amphiboles and plagioclases from two spatially related mylonite zones at the Grenville front are significantly different, suggesting different physical conditions (including temperature) for the formation of the two zones. Oxygen isotopes indicate multiple episodes of fluid-rock interaction, consistent with previously determined mylonitization temperatures and postulated tectonic evolution of the area.

Jan 1, 1982

By W. L. Zeigler

THE gravity concentrator of the Hecla Mining Co. was originally constructed in 1888 by the Milwaukee Mining Co., which was operating the Gem of the Mountains mine. It was purchased by the Hecla Mining Co. in 1900, and placed in operation 2 years later. At that time FIG. 1.-HECLA MINING CO. GEM CONCENTRATOR, GEM, IDAHO. the capacity was only about 200 tons a day, but many additions and changes in equipment have been made so that the present capacity is about 800 tons. One of the outstanding improvements made was the substitution of Callow flotation cells for vanners, which occurred in 1915. The recent building of a flotation plant for treating jig tailings, and the construction of a modern surface plant at the mine, following the

Jan 1, 1927

By A. W. Mitchell

Barite occurs as bedded and vein-type deposits in Nevada along a north-northeast trending zone that Parallels the Antler orogenic belt. The Nevada bedded deposits presently supply 85% of domestic barite production, used primarily as a weighting agent in the petroleum drilling industry. The ore bodies are controlled structurally and stratigraphically along regional and local structural breaks in siliceous eugeosynclinal rocks of lower to middle Paleozoic age. Evidence for the origin of the barite includes sedimentary and hydrothermal features, indicating that localization probably took place along fractures in the sea floor.

Jan 1, 1982

By S. J. Shale

Recent changes at Cornwall are highlighted by development of a panel caving method, with slushing drifts, for underground practice as open pit operation nears close. Metallurgy keeps the pace with high recovery from increasing amounts of harder to liberate, higher sulphide content, underground ore.

Jan 7, 1953

By M. T. Erickson, C. A. Rowland

Ball mills 5.5 m (18 ft) in diameter and larger tend to use energy delivered to the mill less efficiently than smaller diameter mills, particularly when the large mills carry 40% by volume ball charges. This paper will explore factors used in scaling up ball mills, showing where the advantages of one factor can possibly be negated by another factor. The paper will propose possible operating limits and areas for further study to establish selection and design limits.

Jan 1, 1985

By J. A. Herbst, D. W. Fuerstenau

The effect of mill speed and ball load on the dry ball milling of dolomite is examined in the context of the batch grinding model. Observed changes in the parameters of the model are interpreted, as far as possible, in terms of the mechanics of particle motion in the mill. A parameter estimation scheme previously proposed by the authors is shown to provide the basis for a successful simulation of grinding behavior over a wide range of mill speeds and ball loads. Finally, a combination of experimental and simulated results is used to determine the optimum mill speedball load for closed circuit grinding in this mill-material system.

Jan 1, 1973

By J. A. Rajala, R. W. Smith

The effect of increasing ionic strength, via monovalent and divalent ions, on alkyl sulfate flotation of hematite and quartz war investigated. The effects of collector chain length and pretreatment on this flotation were also studied. Sodium hexadecyl sulfate was shown to be a superior flotation collector to sodium dodecyl sulfate for recovery of hematite when there was no salt addition. Similar observation were made when sodium sulfate or sodium chloride was used to control ionic strength. Sodium dodecyl sulfate floated hematite better than its longer chutited counterpart under conditions of low pretreatment temperature and increasing calcium chloride concentration. The flotation recovery for all salt containing pulps was almost always improved after preboiling. Most of the results obtained when the pretreatment temperature was raised were attributed to increased solubility of the collector.

Jan 1, 1984

By R. F. Marande, R. S. Busk

THE magnesium-aluminum-zinc system contains most of the magnesium-base alloys used commercially, although in practice the ternary, alloys are usually modified by the addition of a small amount [ ] of manganese. Table I contains the magnesium-base commercial sand-casting alloys most widely used throughout the world, together with their typical tensile properties. These alloys may be regarded as a single family of varying aluminum and zinc content, disregarding manganese. A concise means of presenting data for them is by means of iso-property lines plotted on triangular coordinate paper. Constitutional, casting, and mechanical properties are presented in this manner. The data are given with the object of providing reference material, and to aid in the choice of a commercial alloy to serve a particular purpose. Detailed, critical analysis of the commercial alloys has been covered in a previous paper.1 [ ] All alloys reported were made in 15-lb. melts, superheated to 1700°F. for 15 min., cooled to 1400°F. and poured in sand molds. The test bars produced had a ½ in. reduced section and were about 6 in. long. Except for the data represented in Figs. I and 3 the alloys used were of commercial purity and contained 0.1 to 0.2 per cent Mn in addition to the aluminum and zinc. CONSTITUTIONAL DATA Under the heading of Constitutional Data are included all known data on con-

Jan 1, 1946

By A. J. W. Headlee

RECENT interest in germanium centers around its use as a semi-conductor of electricity in electronic devices. It is generally believed that germanium transistors, diodes, triodes, photocells, and rectifiers will largely replace the present-day vacuum tubes. The germanium electronic devices are much smaller, lighter, and more resistant to shock, and they require only a small fraction of current required for conventional devices. Hence only a small amount of heat is given off by the equipment. This development will require many times the quantity of germanium now being produced, which in 1948 was approximately 1000 lb1 and was obtained almost entirely from zinc ores in Missouri, Kansas, and Oklahoma. No one knows with certainty what the demand will be for germanium by 1956. It may be 40,000 lb.1 Known concentrations in zinc ores are not sufficient to

Jan 10, 1953

By F. Galasso, A. Paton

ThE recent emphasis on producing boron fibers by reacting boron trichloride and hydrogen on a hot tungsten wire has brought about a renewed interest in the tungsten boride phase diagram. The reaction of the boron with the tungsten core results in the formation of 6 WB, W2B5, and another tungsten boride phase, which was suspected of being the WB4 phase reported by Chrbtien and Helgorsky.1 While the powder-diffraction data for the boride in the fiber and those reported

Jan 1, 1967

By Gerald M. Friedman

CONVENTIONAL usage defines emery as a natural aggregate of corundum and magnetite. Because emery bodies contain abundant spinel two types are recognized, spinel-bearing and spinel- free. Watson and Steiger1 introduced the name spinellite for emery in which spinel is a major constituuent, but this term has not been generally adopted. Spinel emery grades locally into spinel magnetite rocks with or without accessory corundum. Even this variety has been used commercially in the past. The term emery therefore applies to natural aggregates composed of corundum and magnetite; corundum, magnetite, and spinel; and spinel and magnetite.

Jan 7, 1957

The Institute is custodian of funds for support of numerous gold medals and prizes and has representatives on boards awarding still others. Details regarding the Institute Awards are given below. The Institute is represented on the boards of the John Fritz Medal, the Hoover Medal and the Washington Award, in connection with the three national societies of Civil, Mechanical and Electrical engineering; and, also, in the case of the Washington Award, with the Western Society of Engineers. The Institute is represented with these four societies on the committee in charge of the Alfred Noble Prize.

Jan 1, 1937

By J. W. Evans

ONE possible method for the separation of hafnium from zirconium is by the vapor phase oxidation of the purified mixed chlorides. An important factor for success depends on the difference in free energies of the following reactions: ZrCl(g) + O2 = ZrO2(s) + 2C12 [1] HfCl4(g) + O2 = HfO2(s) + 2C12. [2] Prakash and Sundaram1 have calculated these values from certain data and carried out experimental work with partial success. However, their free energy values for reaction 2 diverge rather widely from other data which are presented here. The possibility of successful separation is briefly considered in the light of these alternative values. Table I shows the free energy values (?F°) for reactions 1 and 2 derived from the recent compilation of data on oxides and chlorides by Glassner.2 The corresponding values of Prakash and Sundaram for the same temperatures are also shown. The alternative values to those of Prakash and Sundaram for reaction 2 are substantially confirmed by the data of Kubaschewski and Evans" and Cough-lin' on heats of formation, entropies, and heats of vaporization. In spite of the considerable uncertainty in the hafnium data it is reasonable to suppose that the oxide-chloride free energy difference for two such chemically similar elements would not be very far apart. These figures indicate clearly that the oxidation of hafnium chloride is appreciable at all temperatures. Nevertheless, there is a significant difference between the values for reactions 1 and 2

Jan 1, 1959