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By Thomas Wright

No symposium on die casting could be complete without consideration of the methods of formula and impurity control. No consideration of control would be complete without discussion of that new tool of the analytical chemist and inspector, the quartz spectrograph. Just as there is an increased appreciation of the possible applications of the die-casting process and of die castings, so too is there, slowly but surely, of the spectrograph. At present the role of the instrument might well be compared with that of brass or magnesium die castings. Neither is as widely understood or known as they will be. Product specifications are increasing and are getting more explicit and often more rigid. The designer, metallurgist and production engineer or superintendent will be forced to depend more and more on the chemical laboratory. Sampling, as well as analyses, testing and inspection problems will grow. The chemical laboratory must meet its increased responsibility and use of the spectrograph will become more common. Advantages of increased precision, greater speed, lessened labor and often lower costs cannot be ignored. It will be the purpose of this paper in part to outline the respective fields of chemical and spectrographic analyses and to indicate where one may overlap the other and in part to indicate certain possible sources of contamination of zinc-base die-cast alloys in particular.

Jan 1, 1935

By Theodore H. Eyde

The porphyry-copper province of southwestern United States and northern Mexico constitutes the largest copper-producing region in the world. More than 20 deposits discovered since World War II are being exploited or in the process of exploration and development. Because of the remarkable success in discovering new deposits, exploration activity continues at a very high rate and deeper targets are explored each year. Exploration programs for deeply buried porphyry-copper deposits require a reevaluation of the conventional exploration techniques. Though surface induced-polarization techniques have about reached their practical detection limit, aeromagnetics will play an increasing role in the exploration activity as will downhole logging tools. In addition to a valid geological concept, any successful exploration program for porphyry-copper deposits in the southwest must have two other essential ingredients: money and guts. Unfortunately many exploration programs in the southwest are underfunded and doomed to failure. Future exploration will demand more joint venturing in which larger and more expensive exploration programs can be successfully funded by groups of companies or syndicates.

Jan 1, 1975

By D. M. Hausen

A quantitative x-ray diffraction method has been developed for the analysis of alteration minerals in wallrock. Alteration data are plotted and contoured (analogous to geochemical data). Alteration trends outlined by this technique correlate closely with geochemical anomalies, and in some cases extend well beyond the perimeter of anomalous base metal values. "Monomineralic contouring," applied originally to porphyry-type mineralization, has been extended to other types of mineralization, including volcanogenic massive sulfide deposits. Equipment and techniques used in the quantitative measurement of alteration mineralogy are discussed.

Jan 1, 1980

The practice of fine-grinding is now being so succeesfully carried on in some fields, notably in West Australia, and its advisability has been so frequently pointed out,l that the matter in this paper is not put forward as new; its chief object being to call attention to the importance of fine-grinding in the treatment of comparatively low-grade oree. I' have been engaged daring the last five years in the cyanide-treatment of ores in the Ohinemuri district (North Island), New Zealand, and I consider that, in the near future, extremely fine-grinding (almost sliming) will become a very im-

Jan 1, 1906

By D. B. Reger

DAVID B. REGER.-T Want to 'add that since this paper was prepared a well is now being; drilled it the location recommended do the last page. It was not, however, done at my instance; it was done at the instance of Dr. White, the State- Geologist of West Virginia, who has been trying for several years to induce the large oil and gas companies to make a test of some of these, deep sands in West Virginia and a well is now just being started in Wood County, right at this immediate

Jan 4, 1917

By J. W. Pugh

PREFERRED orientations in cold-rolled body-centered-cubic metals appear to have remarkable similarity. The as-cold-rolled textures in iron,1,2 silicon-iron,3 mild steel,4 molybdenum, vanadium,&apos; chromium,&apos; tantalum,&apos; tungsten,&apos; and a-zirconium-niobium alloys10 have been determined. These textures have, in some cases, been represented by congrUOUS pole figures and have all been described in one or both of two ways. They have frequently been reported as predominantly (100) <011> orientation

Jan 1, 1959

By G. R. St. Pierre, L. M. Adelsberg, R. Speiser

OXIDE platelets have been observed&apos;-3 in oxidized tantalum adjacent to the metal-oxide interface, Fig. 1. The origin and identity of the platelets are important with respect to the proposal of an acceptable mechanism of tantalum oxidation. At reaction temperatures below 750°C, it has been established that the platelets

Jan 1, 1967

By E. C. Truesdale, W. K. Waring

The Research,Division of The New Jersey Zinc Company (of Pa.) has conducted, over a period of years, numerous tests of the reducibility of various zinc ores and the reactivity of various kids of coal, using a number of different experimental methods. Most of these tests have involved the reduction of mixtures of ore and coal. In such cases the following simultaneous reactions are believed to be mainly responsible for the production of zinc, as was shown by Bodenstein&apos; some years ago: ZnO + CO = Zn + CO2 [i] C + COj = 2CO [2] Each of these reactions is dependent upon the other for the supply of CO and COz, respectively, and the over-all rate of formation of zinc vapor will be determined by the slower of these two reactions. An analogous pair of reactions sometimes of importance is: ZnO + He = Zn + HZO 13] C + Hz0 = CO + He U3 While it is possible to obtain an indication of the relative reducibility of various ores, or of a fine versus a coarse Ore, by testing them with a given coal, and while coal reactivities may be measured in a corresponding manner, a more direct determination of relative reaction rates is possible by carrying out the desired reactions, such as I and 2, separately and under reproducible conditions. It is one purpose of this paper to present some of the results that have been obtained by the latter method. C. G. Maier2 discusses the relative rates of reactions I and 2 and concludes that while at relatively low temperatures reaction I is faster than reaction 2, this difference becomes less with increasing temperatures, although at smelting temperatures reaction is still the faster. He also says (p. 48), "At temperatures . . . be- -tween 1100&apos; and 1300°C., . . . the zinc oxide reduction reaction is intrinsically more rapid than its physical limitations; that is, it is limited by gas diffusion rates.&apos;&apos; In the course of numerous reactivity tests involving the separate use of reactions and I and 2, we have obtained data that show by direct experiment, we believe for the first time, the correctness of Maier&apos;s statements concerning these reactions. We also include data on the relative rate of reaction 3, involving reduction by hydrogen. Finally, some interesting results obtained by carrying out the reduction of &apos; a zinc ore-coal briquet in streaming atmospheres of nitrogen, carbon monoxide and hydrogen, respectively, are presented.*

Jan 1, 1944

By E. Gybbon Spilsbury

Everybody who has had his attention turned to the gold-deposits of the Southern States, is acquainted with the undisputed fact of the existence, at least in the Carolinas and Georgia, of enormous areas of gold-bearing rocks. Long before the discovery of the precious metal in California, gold-mining on a very extensive scale mas a well-estab-

Jan 1, 1887

By M. Karfakis, K. Kim, R. V. de la Cruz

The in situ deformability of a closely jointed basalt rock mass was determined by two different methods: the NX-borehole jack method where displacements of opposing curved platens were related to applied hydraulic pressures, and the modified Goodman jack method where tangential strains on the borehole walls were related to induced tangential stresses. The modulus obtained by the modified Goodman jack method were much higher than those obtained by the NX-borehole jack method. To explain the discrepancy, the influence of fractures and test variables, such as depth, orientation, hole location, and applied pressure on the calculated modulus of the rock mass, were analyzed by factorial analysis. It was found that the orientations and measurement depths have statistically significant effects. The in situ deformability values obtained by nonlinear regression analysis were also found comparable with other measurements and empirically predicted values for the basalt rock mass.

Jan 1, 1984

By Michael Richings

Although the role of slope stability has not changed, there have been changes in the mining industry which affect the geotechnician engaged in slope stability studies. The deposits currently being mined or evaluated are technically difficult , capital intensive, and economically marginal. In addition, many mining companies are now either controlled by oil companies or are financing projects through bank loans. The mining investor or decision maker is, therefore, often more sophisticated financially, but less sophisticated in mining terms. The impact of these changes will be to force the geo- technician and mining engineer to attempt to quantify risk and financial implications of a slope design. In conclusion, this paper outlines several questions which mining engineers should be asking those engaged in geotechnical studies and indicates the necessity for the mining engineer and geotechnician to work together and quantify the financial risk associated with a geotechnical design.

Jan 1, 1983

By G. R. St. Pierre, R. D. Blackburn

Oxygen contents of&apos; liquid-iron alloys saturated with oxides are analyzed. Minimum points observed in particular Fe-X-O systems can be predicled by a simple extension of first-order interaction methods. If minimum oxygen content occurs at N; where r is the ratio of metal to oxygen in the oxide phase. RECENTLY, wisher&apos; reported on solubility measurements of A1203 in liquid iron at 1580°C which support the earlier work of d&apos;Entremont, Guernsey, and chipman2 and Gokcen and Chipman. Swisher&apos;s diagram is reproduced in Fig. l. Minimum points in oxide solubilities have also been found in the Fe-Cr-0 system,4 Fig. 2, and the Fe-Ti-0 system,&apos; Fig. 3. Minima positions can be used to confirm approximately the measured first-order interactions, &, cgr, and E&~, in liquid iron and to deduce compositions of components of constant activity in the oxide phases. Consider the solution of Alz03 in liquid iron: for which an equilibrium constant can be written as: differentiating Eq. [2] with respect to Na~, the atom fraction of &l in the metallic solution, and noting that If the activities of Al and 9 are expanded by a first-order interaction model, then:

Jan 1, 1969

By D. F. Toner, P. E. Gage, D. J. Mack

MUCH work has been done on the decomposition of the p phase at the eutectoid composition, 11.9 pct Al, in the Cu-A1 system by Smith and Lind-lief,&apos; Mack,&apos; Klier and Grymko,3 Haynes,4 and others. In all of the mechanisms proposed by these workers for the decomposition of the ß phase, it was stated that the a phase must precipitate rich in aluminum with respect to the equilibrium composition of 9.4 pct A1 at 565°C. To check this hypothesis, it was necessary to have a master curve relating equilibrium aluminum content of a to lattice parameters of a. A number &apos;&apos; binary Cu-Al alloys of increasing amounts of aluminum were prepared by Ampco Metal Inc. These alloys, received as-cast, were given a 30 pct reduction of area by hot-working and then annealed at 900°C for homogenization and slowly cooled in the

Jan 1, 1956

By P. Barnes

In vol.33 of the Proceedings of the Institution of Civil Engineers, London (part 2, for 1870-71), may be found a statement of the cost of two blast furnaces, together with a somewhat detailed description. The attempt will he made in this note to restate these items of cost, so that the information may be rendered perhaps more accessible to our members than in its present place of record, and also in order that the items may be more intelligibly compared among themselves, or with similar items in other cases.

Jan 1, 1879

By N. N. Breyer, W. R. Warke, S. Dinda

A model for the low-temperature peak, LTP, in fcc metals is presented. In high stacking fault energy metals, e.g., aluminum and nickel, it is proposed that a reversible dislocation glide and climb process might give rise to the observed high relaxation strengths and activation energies equivalent to volume self-diffusion values. In low stacking fault energy metals such as copper, gold, and silver, dislocation climb is energetically unfavorable at T < 0.5 Tm and the relaxation process is therefore mainly one of reversible glide. This model is used to explain the effect of a change in grain size and impurities on the LTP. THE low-temperature grain boundary damping peak, LTP, in spectroscopically pure aluminum,&apos; copper,17&apos; gold,2 nickel,3 and silver4 has recently been the subject of a detailed investigation by our laboratory. The main results are summarized in Table I. An empirical relationship was found between the peak relaxation strength, AE, and the width of the dissociated dislocation, do,* given by: do = µa2/24p? (Ref. 5) [I] where p is the shear modulus, y is the stacking fault energy,6-8 and a is the lattice parameter, Table 11. 4E is plotted against do in Fig. 1. Two regions are apparent: region (a)! which contains all but one of the metals, where AE decreases linearly with increasing do, i.e,, AE 1/do; and region (b), where ?E is approximately independent of do. A similar trend is observed when the ratio Qp/QL is plotted as a function of do, Fig. 2. (Qp and Ql are the activation energies for the peak and for lattice diffusion, respectively). In the past, when Qp and QL were found to be comparable, the relaxation peak was explained in terms of grain boundary sliding.10 The equivalence of Q, and Qb. the activation energy for grain boundary diffusion, prompted the suggestion that it was a consequence of reversible grain boundary migration on an atomic scale." A new model for the LTP, which is based on the experimental relationships in Figs. 1 and 2, is presented. In region (a) it is suggested that stress relaxation occurs through the reversible glide and climb of grain boundary dislocations; in region (b) only reversible glide can take place. The resultant effect on the grain boundary might be sliding or "a bowing out", but, since the total distance moved will be 50A, the atomic movements are considered of primary im- portance. It must be emphasized that this is only a qualitative model, but at the moment it appears the most likely way to explain the widely varying, but re-

Jan 1, 1969

By C. G. Fink, G. L. Putnam

The dissolution of gold by cyanide solutions was studied by determining the time required for the solvents to dissolve gold leaf. Minute traces, even 0.5 ppm, of sulphide ion retard the dissolution of gold, and this behavior cannot be accounted for by the presently accepted hypotheses involving oxygen-depletion or thiocyanate formation. On the other hand, traces of the salts of lead, bismuth, mercury, and thallium considerably accelerate the dissolution. The beneficial effect of lead is dependent upon the pH and cyanide ion concentration of the solution.

Jan 9, 1950

MELTING in a hearth and in a basket is almost the same thing; charcoal and bellows are used for both. These are made large or small according to the quantity that you wish to melt, and more or less force of the bellows is applied according to the need. The hearth, bowl, or refinery, as the masters call it, is made with bricks and clay like a forge; opposite the middle of the tuyère a round hole is made like a wash- basin, wide at the mouth and narrow at the bottom where there is a hole for emptying it. A little iron plug is put in this so that it may be closed when necessary, or a piece of brick that is cut and pointed. Now, when this has been well covered all over with ashes, and the tuyère has been arranged so that the wind strikes the center, it is first filled with charcoal and baked very well so that the metal may be kept hot once it has been melted. When it has been baked, it is again filled with charcoal, fire is applied, and it is left to inflame gradually by itself. Then put one or

Jan 1, 1942

By S. V. Krishnan, I. Iwasaki

In the upgrading of finely disseminated iron ores, selective desliming is the critical step that must be controlled to achieve efficient flotation. A prerequisite for selective desliming is a properly-dispersed pulp; sodium silicate is commonly used as a dispersant. The mechanism by which sodium silicate acts as a dispersant in the presence of calcium ions was examined by streaming potential measurements, settling tests, abstraction density determinations, selective flocculation tests, and scanning electron microscope observations. The study established that calcium silicate precipitates on the mineral surfaces dispersed the pulp. Although sodium silicate was a nonselective dispersant, the addition of corn starch aided flocculation of goethite over quartz at low silicate additions, but became ineffective at higher silicate levels. A model is presented to explain the dispersant mechanism of sodium silicate in the presence of calcium ion for selective flocculation of iron ores.

Jan 1, 1983

By H. Conrad, V. Damiano, J. Hanafee, N. Inoue

The effects of hydrostatic pressure up to 400 ksi at 25" to 300°C on the mechanical properties of three forms of commercial beryllium (hot-pressed block, extruded rod and cross-rolled sheet) were investigated. Three effects of pressure were studied: mechanical beharior under pressure, the effect of pressure-cycling, and the effect of tensile prestraining under hydrostatic pressure on the subsequent tensile properties at atmospheric pressure. For all three materials the ductility increased with pressure whereas the flow stress did not appear to be significantly influenced by pressure. An increase in the subsequent atmospheric pressure yield strength generally occurred as a result of pressure-cycling or prestraining under pressure, whereas either no change or a decrease in ductility occurred. The only exception to this was sheet material, which exhibited some improvement in ductility following a pressure-cycle treatment of 304 ksi pressure. The effects of pressure-cycling and prestraining were relatively independent of the temperature at which they were conducted. Stabilized cracks of the (0001) type were found in hot-pressed specimens and {1120) type in extruded and sheet specimens following straining under pressure. Also, pyramidal slip with a vector out of the basal plane, presumably c + a, was identified by electron transmission microscopy for extruded rod and for sheet strained under pressure. Small loops similar to those previously reported were found after straining at pressures of the order of 300 ksi. THE use of beryllium in structures is limited because of its poor ductility under certain conditions. Therefore, one objective of the present research was to determine if the ductility of beryllium at atmospheric pressure could be improved by prior pressure-cycling or prestraining under hydrostatic pressure. Another objective was to study the mechanisms associated with the plastic flow and fracture of the polycrystalline form of this metal with pressure as an additional variable. Since the early work of Bridgman,1 it has been recognized that many materials which are brittle at atmospheric pressure exhibit appreciable ductility when strained under high hydrostatic pressure. This effect has been reported for beryllium by Stack and Bob-rowsky2 and by Carpentier et al.3 and has been attributed to the operation of pyramidal slip systems with slip vectors inclined to the basal plane while cleavage or fracture is suppressed.4 That such slip may occur simply by the application of pressure alone without external straining (pressure-cycling) is suggested by the results on polycrystalline zinc5 and polycrystalline beryllium,6 where nonbasal dislocations with a vector (1123) were reported. A significant improvement in the ductility of the bee metal chromium by pressure-cycling has been reported.7 On the other hand, limited studies on the pressure-cycling of the hcp metals zinc67819 and beryllium6 indicated no improvement in ductility; there only occurred an increase in the yield and ultimate strengths. The study on beryllium was limited to hot-pressed material. Consequently, additional studies on the effects of pressure-cycling on other forms of beryllium seemed desirable, especially since for chromium some authors10 have been unable to detect any improvement in ductility while others find a large improvement.7 That the ductility of polycrystalline beryllium at atmospheric pressure might be improved by prior straining under hydrostatic pressure was suggested by the known beneficial effects of cold work on the ductile-to-brittle transition temperature in the bee metals. It was reasoned that, by straining under hydrostatic pressure, fracture would be suppressed, and during the propagation of slip from one grain to its neighbor dislocations with a vector inclined to the basal plane"-&apos;4 would operate. Upon subsequent straining at atmospheric pressure, these dislocations with a nonbasal vector would continue to operate and thereby reduce the tendency for fracture to occur, by assisting in the propagation of slip across grain boundaries and by interacting with any cracks that may develop. It was recognized that maximum improvement in ductility would probably occur at some optimum amount of prestrain under hydrostatic pressure. If the pre-strain was too small, an insufficient number of dislocations with a nonbasal vector would be activated; if it was too large, internal stresses (work hardening) might increase the flow stress more than the fracture stress, or incipient cracks or other damage could develop. EXPERIMENTAL PROCEDURE 1) Materials and Specimen Preparation. The materials employed in this investigation consisted of hot-pressed block (General Astrometals, CR grade), extruded rod (General Astrometals, GB-2 grade with a reduction ratio of 8:1), and cross-rolled sheet (Brush S200, 0.065 in. thick). The analyses of these materials and mechanical properties at room temperature and atmospheric pressure are given in Table I. The grain size of the hot-pressed block was 15 to 16 µ, that of the extruded rod 10 to 11 µ, and that of the sheet 7 to 10 µ in the rolling plane and 5 to 6 µ in the thickness, all determined by the linear intercept method. Al-

Jan 1, 1969

By d&apos, C. McCoul, C. Antonio, R. Krohn

MOST of the commercial colored gold alloys for jewelry applications are based on the Au-Ag-Cu-Zn system. Although work has been done on the constitution of the Au-Ag-Cu system.&apos;-4 there are no reports in the literature on the effects of zinc additions in these alloys. We have metallographically determined the a =al + a2 transformation temperatures in 91/2- and 131/2-karat alloys in which varying amounts of zinc have been substituted for copper and silver. Samples were cast in the form of 1/2-in. round bars

Jan 1, 1970