Search Documents

By Theron Wasson

Michigan's production of 17,301,000 bbl. in 1945, which is in line with previous years, has been maintained by extensions to old fields like Deep River, Adams, Fork, and others. There were a number of new discoveries but, as in the past, these are not given very much importance because enough drilling has not been done to develop their potentialities; however, judging by the past, some of them will develop enough production so that 1946 -will probably be in line with other years. Activities in Michigan were confined to the Basin area of the lower Peninsula, which has been under development since 1925.

Jan 1, 1946

By N. S. Wagner

The production of lightweight aggregates in Oregon is a new industry, and, like all new enterprises, it is suffering from growing pains characterized by numerous, small operations some of which flourish for a short time and then cease altogether. Normally all industrial mineral products are produced in a highly competitive atmosphere. At the present time this condition does not exist to a very marked degree in the state because as yet producers have not saturated the constantly expanding market. This paper has been prepared with the intention of outlining very briefly the current status of the various products now being used as lightweight aggregates in Oregon. The present picture will surely change, perhaps quite radically within even a short space of time.

Jan 1, 1949

By C. Chiou, D. P. Seraphim

The effect of clustering on the superconducting properties of Al-Zn alloys has been studied by the ballistic induction techniques. The superconducting critical temperature, T,, changes when zinc-rich clusters are formed. The change in T, depends on the concentration and may be positive or negative, but always correlates with an effective decrease in the solute concentration of the alloy. Reversion after clustering effectively returns a 5 at. pct Zn alloy to the quenched state. These methods might be use&lly extended to the Al-Mg system, where X-ray data are difficult to obtain. In very dilute Al-Zn alloys, as in other tin,' indium, aluminum,2 or tantalums base solid solutions, there is a decrease in the superconducting critical temperature, Tc, roughly proportional to the temperature independent resistivity, i.e., -0.2°K per pS2cm. With increasing solute concentration, the T, generally reaches a minimum and then increases4 to a value well above that for the pure solvent. The change of T, with solute concentration follows an empirical formulation involving two constants which correlate with the scattering cross section of the impurities. As will be shown below, the Al-Zn alloys more concentrated than 1or2at. pct do not follow the empiricism, probably because they are unstable even when rapidly quenched.5 However, it seems possible to study at least the later stages of solute clustering by precise measurements of the 1', following various thermal treatments. A few experiments on quenched alloys, aged alloys, and tests on reversion are reported here. The heat treatments selected for obtaining the quenched and aged states were mainly deduced from the work of Dash and Fine.6 For the quenched state, specimens were homogenized at 480°C, quenched to -160°C, and immediately transferred and mounted in liquid nitrogen. Measurements on the superconducting properties and residual resistivities were then made at helium temperatures, after which the specimens were aged at room temperature for 3 to 5 hr, i.e., much longer than the time required for clustering to be essentially completed. The superconducting properties and residual resistivities were once again examined. To reach the reverted state of the A1-5at. pct Zn alloy, the aged specimen was heated for 5 min at 200°C and then tested as above.

Jan 1, 1963

US Tin Mission To Study Costs in Far East A move to obtain adequate supplies of tin at prices the United States is willing to pay was initiated when the interagency tin mission left for the Far East. The Mission, which includes representatives of the Reconstruction Finance Corporation, State Department, Defense Minerals Procurement Agency and the Bureau of Mines will go to Indonesia and Malaya. The primary purpose of the mission, according to officials, will be to study tin production costs, not to negotiate for the purchase of tin. The mission will be prepared to enter into negotiations, if the Far Eastern producers are amenable. The United States withdrew as a large-scale buyer of tin some months ago in protest against what it considered exorbitant prices being charged in the Singapore market. Subsequent attempts to negotiate for a steady tin supply at what this country considers reasonable prices have been unavailing. The U. S. is prepared to enter into a two or three year contract with the price of tin somewhere between $1.00 to $1.12 per lb. The decision to abstain from the market has not yet put a squeeze on U. S. supplies. Substantial quantities of tin still are coming in from Malaya under an old contract.

Jan 12, 1951

By N. S. Stoloff, K. R. Jordan

The temperatwe and grain size dependence of the mechanical avoperties of ordered and disordered Fe-49 pct Co-2 Pct V were investigated. The yield and flow stresses obeyed the Hall-Petch relationship u = ai + kd-&apos;I2. Ohdering reduced the intercept stress cjj and raised the Petch slope, k, at all temperatures. Ordering also increased the temperatwe dependence of k. The ductile to brittle transition temperature increased with order and grair~ size. Cleavage fracture was nucleation limited and the fracture stress did not zlary linearly with d-&apos;". A quantitative test of the Cottrell-Petch fracture theory (and recent modifications which consider the influence of slip mode), demonstvated that this theory is not applicable to FeCo-V. COTTRELL&apos; and etch&apos; independently suggested that a criterion for cleavage failure at the yield point, a,, based on dislocation pileups at a grain boundary or other obstacle to dislocat.ion motion, is: aYYkd&apos;I2 1 opy [ll or, equivalently, aikz,d112 +k:)bpy [2] where a, and ky are the Hall-Petch intercept and slope, respectively, 2d is the grain diameter, P is a geometric factor dependent on the macroscopic ratio between shear and tensile stress, p is the shear modulus, and y is the true elastic surface energy. When the product of quantities on the left side of the equation is equal to or exceeds that on the right, cracks should be able to nucleate and propagate at the yield stress, as shown schematically in Fig. 1. Therefore a high intercept stress, high Petch slope, or coarse grain size favors brittleness. petch3 associated the existence of a ductile to brittle transition in ferrous alloys with the temperature dependence of ai. One of the earliest modifications of the Cottrell-Petch theory was presented by ~rmstrong,~ who derived an expression for transition temperature in terms of several measurable flow and fracture parameters. The latter paper was able to rationalize situations in which the transition temperature increases with decl-easing grain size, as in the case of molybdenum,&apos; and also suggested that Ppy should be a function of grain size as well as temperature. More recently Johnston et a1.6 and Smith and worthington7 have suggested that the temperature or composition dependence ol&apos; ky must also be taken into account if there is any cha.nge in deformation mode, as from wavy to planar slip, or wavy slip to twinning, with change in temperature or solute content. Armstrong %as suggested that for hcp metals changes in o;k,dw> o;k,d1/2< / is / ^^^^ / / y_______________________________________ d-"2 Fig. l—Schematic representation of grain size dependence of yield stress, cry, and fracture stress, CTF. Intersection defined by Cottrell-Petch equation. slip mode should be incorporated in the theory through changes in the critical resolved shear stress for the slip system which controls ky. The purpose of the present investigation was to critically test the modified677 Cottrell-Petch theory of fracture in the superlattice alloy Fe-49 pct Co-2 pct V, by studying the grain size dependence of the yield and fracture stresses over a range of temperatures, in conjunction with an investigation of slip mode and fracture behavior. Previous work has shown that long range order results in a sharp decrease in flow stress, a small increase in work hardening rate and a drastic upward shift in the ductile-brittle transition temperature of F~CO-V.~&apos;~ The only comprehensive study of slip character in this alloy has been reported in a preliminary account of the present investigation.10 EXPERIMENTAL PROCEDURE The experimental work was carried out on material produced from a 10 lb vacuum melted ingot, of composition 49.32 wt pct Co, 2.09 wt pct V, balance Fe. 30-mil thick sheet samples with a 1; in. gage section were machined from cold rolled stock. The degree of cold work ranged from 85 pct for the finest grained samples to 5 pct for the coarsest grain size. Details of ingot fabrication are reported elsewhere." Equi-axed grain sizes in the range 12.7 to 75.4 p were obtained by annealing for varying times at 850°C. (Re-crystallization annealing time, rather than temperature , was varied to control grain size to insure that samples of all grain sizes contained equivalent quenched-in vacancy and interstitial concentrations.) Grain sizes were measured by the line intercept method on several specimens of each grain size. Following recrystallization, all samples were disordered by quenching into iced brine.

Jan 1, 1970

By E. C. Bohlen, H. l. Burghoff

THE work reported in this paper was carried out to supplement the existing information concerning directional properties and recrystallization textures of annealed brass sheet and strip. These characteristics are of direct interest when the forming and drawing properties of such material are being considered. Among those who have made contributions in this field are Bass and Glocker;1 Bauer, Göler and Sachs;2 Phillips and Samans;3 Pratt;4 Price;5 Cook;6 Richards;7 Brick;8 and Brick and Williamson.9 These investigators have found, in general, that in brass strip that shows directional variations in properties, tensile strength has a minimum value and elongation has a maximum value at 45° to the rolling direction. The most pronounced directional properties have been found in material given the greatest reductions in rolling followed by high annealing temperatures. Recrystallization texture of brass has been variously reported as (113)[112], (001)[100], and a combination of (110)[115] and traces of the primary rolling texture, (110)[112]. The directional studies have been very informative, but actual tests appear to have been confined to material in its final condition. Tests at intermediate stages have received little attention although previous history of some materials has been partly considered. Perhaps the most comprehensive investigation was made by Cook,6 who studied the directional properties of 70-30 brass strip for which the final and penultimate, or next to the last, anneals and the final reductions were varied. He found that, for any given combination of penultimate anneal and final reduction, the tendency toward the development of directional properties was reduced as the temperature of the final anneal was decreased. In addition to drawing cups and making tensile tests of the finished material at various angles to the rolling direction, he measured the frequency and the angles of twins in grains for several specimens. Plots of his twin counts showed directionality for the materials that produced eared cups. TEST MATERIALS AND EQUIPMENT For this investigation, one commercial heat of 68-32 brass was cast in the form of bars for cold-rolling, 13 ½ in. wide and 1 ½ in. thick. The analysis was as follows: 68.83 per cent copper, 0.04 per cent lead, 0.01 per cent iron, 31.12 per cent zinc (by difference). The bars were so processed to the final thickness, 0.020 in., as to obtain on this thickness all possible combinations of the variables listed below except those involving the sequence of 84 per cent penultimate reduction and 84 per cent final reduction: I. Penultimate reductions of 37 per cent, 50 per cent and 84 per cent; 2. Penultimate anneals at 800°, 900°, 1050° and 1200°F.; 3. Final reductions of 37 per cent, 50 per cent, 69 per cent and 84 per cent;

Jan 1, 1942

By T. D. Mueller, H. Dykstra

This paper describes a method for obtaining compositions of gas and oil phases in equilibrium with each other at a given reservoir temperature and pressure as lean or enriched gas is injected into a reservoir oil not in equilibrium with the gas. The method is based on calculation of equilibrium constants, K, from the equation log Kp = A + B F, where p is pressure and F is component characterization factor. A and B are constants that vary with a composition parameter. The paper explains how A and B could be determined with a minimum amount of data. The method consists of calculating equilibrium constants as a function of liquid composition and using the K&apos;s to calculate changes in compositiort of injection gas as it successively contacts original resetvoir oil at the gas-oil front and the change in composition of reservoir oil as it is successively contacted by the injection gas in the vicinity of an injection well. An iterative process is required. Two examples of the method are given which show how oil and gas compositions and properties are calculated with the aid of a computer. INTRODUCTION The calculation of recovery from lean-gas or enriched-gas injection into a saturated or under-saturated reservoir oil requires a knowledge of how phase properties change in a reservoir between injection well and producing well. To determine the phase compositions or properties experimentally would be difficult and time consuming, especially if one wanted to look at the effect of various injection gas compositions. For some fields an engineer would want to make preliminary calculations on the economics of gas injection before he makes the decision to spend a corrsiderable sum of money for laboratory work to obtain the necessary fluid properties. A method for calculatine compositions and properties based on a minimum of laboratory data is described. The minimum amount of data required is injection gas and reservoir oil composition and injection gas solubility as a function of pressure for an undersaturated oil, or the compositions of mixtures of reservoir fluid with two or more enriched gases, which mixtures have a bubble-point pressure that is the same as the expected average displacement pressure. On the other hand, if the economics appear to be attractive, more laboratory data can be obtained in the form of equilibrium constants for three or more mixtures of the reservoir fluid and injection gases. The method is based on the calculation of K&apos;s from the equation, log Kp = A + B F, where K is equilibrium constant, p is pressure and F is component characterization factor. This method of plotting K data by means of the above equation is described by Hoffman, Crump and Hocott.1 A and B are constants that vary with a composition parameter. It is shown how experimental data are used to determine how A and B vary with composition. BASIS OF METHOD EQUILIBRIUM CONSTANTS Equilibrium constant (K) data are required for this method. The K of each component is obtained from an equation that gives the product of K and pressure as a function of component characterization factor. The characterization factor F = b(l/Tb — l/T), where b is a constant characteristic of a given component, Tb is the boiling point in OR at atmospheric pressure of the given component, and T is the temperature of the system in OR. This method of plotting K data is described by Hoffman, Crump and Hocott.l The straight-line equation of the log Kp - F plot is log hp = log Kop +BFi, where Kop is at F =0, i designates the component, and B is the slope of the line. The factor F can be

Jan 1, 1966

By J. E. Hilliard

AS is well-known, the length per unit volume, Lv, of any lineal feature (such as grain edges in a polycrys-talline specimen) can be estimated from a count of the number of point intersections with a random plane of polish. Specifically:&apos; Lv = 2NA in which NA is the expected number of intersections per unit area of the plane. As with all other measurements in quantitative metallography, the estimation of Lv is subject to a sampling error, the magnitude of which will depend on the number of observations. The analysis is usually performed by counting the number of intersections falling within a closed test figure of known area applied to a succession of different areas on the plane of polish. The test figure can be drawn directly on the screen of a projection microscope or else superimposed on the image of the structure by means of a reticule in a focusing eyepiece of an ordinary microscope. The use of micrographs is very inefficient unless, as in the present study, these are also needed for some other purpose. Consider an analysis in which n applications are made of a test figure within which the expected number of intersections is N. The expected total number of intersections counted is then given by NT = nN If (N) is the standard deviation in N for one application of the figure and if the latter is applied to non-overlapping regions so that the N&apos;s are independent in the statistical sense, then the standard deviation in Nt is given by: a(NT) = a(N)vn Eliminating n from Eqs. [2] and [3] we obtain: Thus, k will be a constant for a given specimen and test figure. From Eqs. [ I] and [4] we find As is to be expected, therefore, the fractional error in the estimation of Lv is inversely proportional to the square root of the total number of intersections counted. It is very desirable to have at least a rough estimate of k before starting an analysis, since it will then be possible to decide in advance by use of Eq. [5J how many counts should be made in order to achieve the desired accuracy in Lv. Without such information the investigator, unless lucky, will either do needless (and tedious) work or else obtain a result with too large an error. It is very easy to calculate k for the limiting case of N — 0, i.e., when the test figure is vanishingly small. In this case there is a negligible probability of two or more intersections falling within the figure. There are therefore only two possible outcomes: a count of one with a probability of, say, p and a zero count with a probability of (I-p). Thus and Therefore: We might expect k to depend on N and therefore on the size of the test figure. Such a dependence was observed2 in the analogous case involving the estimation of grain-boundary area per unit volume by a count of the number of intersections of a test circle with traces of the boundaries on the plane of polish. In this case the theoretical value of k at the limit N — 0 was 1.41. It was also predicted that k would display an initial sharp decrease with increasing N. Experimentally, k was observed to decrease to a value of 0.62 at N - 6 and thereafter remain approximately constant. Furthermore, the value of k for N > 6 was found to be insensitive to the form of the structure provided no pronounced anisotropy or grain-size variation was present. In order to determinewhether k would exhibit a similar dependence on N in the estimation of grain-

Jan 1, 1967

By S. M. Marshall, A. C. Richardson, H. Y. Yancey

A year ago, Marshall and Bird presented a paper in which a new method of measuring the agglutinating power of coal was described.&apos; The procedure used was to determine the strength of a button containing 10 parts sand and one part coal, formed by carbonizing the mixture in a crucible in an electric furnace. The result of the determination was reported as the total weight in grams required to bring about complete destruction of the button. Correlations were shown between the agglutinating value and some of the characteristics of the different coals that were investigated. This agglutinating test has been in use fairly continuously during the past five years for coals of widely differing coking qualities, and it has shown reasonably concordant results accurate enough for commercial use, although there are many features of the test which should have further scientific study. During the past year a study has been made of some coals of low coking strengths, and incidental to the main investigation some data which appear to be of interest and value were obtained on the loss in agglutinating power caused by exposure to the air. Three coals were investigated, all of which were of the Tertiary age; two were from one field in Asia, and one from a field in the United States. The three were similar, as shown by the proximate and ultimate analyses in Table 1 (moisture-free basis). Coals SA and RA generally contain about 5 per cent. moisture and coal P about 3.5 per cent. moisture on the as-received basis. The large difference in the ash contents of the coals, amounting to practically 10 per cent. between SA and RA, and P, makes difficult a direct comparison of their qualities. In the second section of Table 1 the figures have been put upon an ash-free basis., This table shows that these coals are closely alike. The ultimate analyses are almost identical except for the higher nitrogen content of

Jan 1, 1930

By H. Vincent Wallace

ALTHOUGH it is universally accepted that free oxygen is A necessary in a cyanide solution for the dissolution of gold and silver-in accordance with Elsner&apos;s equation that 2Au + 4KCN + 0 + H20 = 2KAu (CN), + 2KOH- little has been written and insufficient attention paid to the drop in extraction due apparently to loss of dissolved oxygen in mill solutions. Aeration or oxygenation of cyanide solutions has been more or less successfully accomplished by various types of agitators such as the Dorr (with or without air lifts), Pachuca tanks and more recently "Turbo-mixers" and Denver "Super- agitators"; also by the introduction of chemical oxidizing agents such as Solozone (Na,O,) . At the Wright-Hargreaves and other mines in the Kirkland Lake camp, the introduction of this reagent at the rate of about 1.25 oz. per ton of ore applied to the feed of the ball mills has certainly been beneficial.

Jan 1, 1932

By Dale A. Vaughan, Oliver M. Stewart, Charles M. Schwartz

Solid-solubility limits at 1500°, l000q and 500°C for carbon, nitrogen, and oxygen in high-purity tantalum were determined by X-ray lattice-parameter methods. For carbon, the solubility was found to be 0.17 at. pct at 1500°C, and less than 0.07 at. pct at 1000°C. A nitrogen solubility of 3.70 at. pct at 1500° C decreases linearly with temperature to 2.75 at. pct at 1000°C, and 1.8 at. pct at 500°C. In the case of oxygen, the solubility was found to be 3.65 at. pct at 1500°C, 2.95 at. pct at 1000°C, and 2.5 at. pct at 500°C. The phases Ta2C, the low-temperature modification of Ta205, and Ta,N of unknown composition but which has a superlattice structure based upon the original bcc tantalum lattice have been identified as the initial precipitates in the respective systems. Metallographic methods were employed to verify the X-ray analyses. The etching behavior of Ta is discussed in terms of lattice i?rzperfections and precipitate phases. The excellent fabricability, high melting point, and nuclear properties of tantalum are responsible for interest in this refractory metal. Data on the solid solubility of the interstitial elements (oxygen, nitrogen, and carbon) in tantalum and on the precipitate phases are somewhat limited. The significant contributions are discussed below. Because the purity of electron-beam melted tantalum (only recently available) is considerably higher than that used in previous studies, the present investigation was initiated. Gebhardt et all-3 have investigated the tantalum-oxygen and tantalum-nitrogen systems with particular reference to the changes in physical properties and to the rates of reaction between these gases and the metal. The solubility of oxygen in tantalum was reported2 to be 3.7 at. pet at 1500°, 2.3 at. pet at 100O°C, and 1.4 at. pct at 750°C. Schonberg4 reported that several oxide phases (Ta40, Ta,O, TaO and Ta,05) exist while X-ray studies by Gebhardtl showed only two oxides, Ta,05 and an unidentified phase which was associated with a platelet-type precipitate. La-gergren and Magneli,&apos; however, questioned the existence of compounds other than the two allotropic modifications of Ta,05 for the tantalum-oxygen system. In the case of nitrogen, the solubility was estab- lished by Gebhardt3 to be of the order of 7 at. pct at 1800°c. The solubility was reported to decrease rapidly with temperature, and, although no limits were established, a precipitate phase was observed by Gebhardt except when the high-nitrogen specimens were cooled very rapidly from the reaction temperature of 1800c. He reported the initial precipitate phase to be a tetragonal distortion of the bcc tantalum lattice while Schonberg6 reported the phase lowest in nitrogen Jo be a cubic super-lattice with a cell size of 10.11 A. Two other nitride phases, Ta,N and TaN, were reported; these appear to be isomor-phous with the carbides of tantalum. The tantalum-carbon system was investigated by Ellinger7 and by Lesser and Braurer. Two compounds, Ta,C and TaC, were reported to exist, each with a range of composition. The solubility of carbon in tantalum was found to be practically nil at all temperatures. Thus, of the interstitial elements which are present in small amounts in high-purity tantalum, carbon might be expected to form precipitates. The present investigation was initiated to obtain additional data on the solid-solubility limits of these interstitials at 1500°, 1000°, and 500&apos; with particular emphasis on the distribution and the identification of the precipitate phases. EXPERIMENTAL WORK AND RESULTS In the present investigations of the solid solubility and of the precipitate phases in the systems tantalum-nitrogen, -oxygen, and -carbon, high-purity tantalum was reacted with high-purity gases, homogenized at 1800°c, and annealed at and quenched from 1500°, 1000,

Jan 1, 1962

By William L. Fink, E. H. Dix, L. A. Willey

The results of a preliminary investigation of the aluminum-iron-manganese system showed that small amounts of iron (0.10 per cent) substantially reduce the solid solubility of manganese in aluminum. This is clearly shown in the photomicrographs of three alloys, Figs. 1 to 3. Fig. 1, of an alloy containing 1.04 per cent manganese after a heat treatment at 626° C. for 45 hr., shows only solid solution. This alloy contained less than 0.008 per cent iron. Fig. 2 shows the abundance of a constituent (which undoubtedly contains aluminum, manganese and iron) in an alloy containing 1.00 per cent manganese and 0.11 percent iron after a solution heat treatment at 625" C. for 63 hr. For comparison, Fig. 3 is included to show the relatively small amount of constituent (FeA13) in a similarly heat-treated aluminum alloy containing 0.10 per cent iron but no manganese. These data necessitated a reconsideration of the binary aluminum-manganese diagram that was previously presented,&apos; inasmuch as the alloys used in that work contained from 0.02 to 0.05 per cent iron. This paper is the fourteenth of a series from the Research Laboratories of the Aluminum Company of America reporting the results of investigations of equilibrium relations in aluminum-base alloys of high purity. The purpose was to determine the phase relations in aluminum with aluminum-manganese alloys containing the smallest amount of iron that could be realized with the purest material available at the present time (less than 0.01 per cent iron). Since the previous publication from these laboratories, five investigations of the aluminum-manganese system have been reported. Krings and Ostmannz assigned the formula MnA14 to the compound at the aluminum end of the syst,em, and found a eutectic between this compound and aluminum at 649" C. and 3 per cent manganese.

Jan 1, 1933

By Howard Scott

INVAR is the preeminent low-expansion metal by virtue of the fact that it can be prepared with a zero coefficient of expansion at atmospheric temperature. This fact suggests that there is little room for improvement in the expansion properties of the low-expansion nickel steels. The inference is true, however, only so far as the expansion at and near atmospheric temperature is concerned, because the expansivity of invar starts to increase rapidly on heating above 100° C. and soon reaches the value of copper. Guillaume1 met this situation by increasing the nickel content above that of invar. By that expedient, alloys having low expansivity under higher temperatures were obtained, but not without a large increase in minimum expansivity. The increase in minimum expansivity with increasing nickel content severely limits the technical applications of these alloys at high temperatures. Prospects of improving the expansion characteristics of the nickel steels is offered by alloying. Search for an advantageous alloying addition by analogy with other alloy systems, however, is not productive because the low-expansion characteristic is unique with that system. The rule of mixtures usually gives a fair value of the expansivity of other solid-solution alloys, but in the iron-nickel systems gives a value of 18 X 10-6 per deg. C. whereas the actual value is 1 X 10-6 per deg. C. Apparently suitable additions are not to be deduced from such ingenuous considerations. Recognition of the fact that the temperature range of low expansivity in nickel steels is terminated with loss of magnetism affords a more promising basis for the selection of an advantageous element. One may expect from that fact that additions of nonmagnetic elements to the iron-nickel alloys are detrimental to the low-expansion characteristic. Indeed, carbon, manganese, silicon, copper and chromium are detri-mental to the expansion properties and no nonmagnetic element is reported to be beneficial. From the same viewpoint, the addition of a magnetic metal offers prospects of improvement. As two of the three ferromagnetic elements are already present in the

Jan 1, 1930

By Howard Scott

Invar is the preeminent low-expansion metal by virtue of the fact that it can be prepared with a zero coefficient of expansion at atmospheric temperature. This fact suggests that there is little room for improvement in the expansion properties of the low-expansion nickel steels. The inference is true, however, only so far as the expansion at and near atmospheric temperature is concerned, because the expansivity of invar starts to increase rapidly on heating above 100" C. and soon reaches the value of copper. Guillaumel met this situation by increasing the nickel content above that of invar. By that expedient, alloys having low expansivity under higher temperatures were obtained, but not without a large increase in minimum expansivity. The increase in minimum expansivity with increasing nickel content severely limits the technical applications of these alloys at high temperatures. Prospects of improving the expansion characteristics of the nickel steels is offered by alloying. Search for an advantageous alloying addition by analogy with other alloy systems, however, is not productive because the low-expansion characteristic is unique with that system. The rule of mixtures usually gives a fair value of the expansivity of other solid-solution alloys, but in the iron-nickel systems gives a value of 18 X 10-6 per deg. C. whereas the actual value is 1 X 10-6 per deg. C. Apparently suitable additions are not to be deduced from such ingenuous considerations. Recognition of the fact that the temperature range of low expansivity in nickel steels is terminated with loss of magnetism affords a more promising basis for the selection of an advantageous element. One may expect from that fact that additions of nonmagnetic elements to the iron-nickel alloys are detrimental to the low-expansion characteristic. Indeed, carbon, manganese, silicon, copper and chromium are detrimental to the expansion properties and no nonmagnetic element is reported to be beneficial. From the same viewpoint, the addition of a magnetic metal offers prospects of improvement. As two of the three ferromagnetic elements are already present in the

Jan 1, 1930

By Gerhard Derge, Harold Markus

The introductory paper1 of this series described the potential behavior of tin in sodium carbonate and bicarbonate solutions whose pH ranged from 8.4 to 11.2 and demonstrated that significant and reproducible results could be obtained by proper attention to experimental technique. In examining the corrosion of tin under such conditions, it is desirable to know the effects of anions, aside from carbonate, that are likely to be present in commercial materials packaged in tin. Therefore, in this paper the potential behavior of tin in carbonate solutions to which sodium fluoride, chloride, bromide, iodide, sulphate, nitrate, monobasic phos-phate, dichromate, perborate and acetate have been added will be dcscribed. For most of the additions, solutions containing 0.001 and 0.01 moles of the added material were studied. The experimental procedure was exactly the same as that described in the first paper; the pH of the electrolyte was controlled by adjusting the ratio of carbonate to bicar-l,ol~ate as follows: pH 0.1 M NaHC0............................................ 8.4 2 parts 0.1 M XaHCOr, 1 pa.rt 0.1 M NaZCO?................. 9.5 1 part 0.1 M NaHCOs, 2 parts 0.1 M iVa.,C03. ................ 10.0 0.1 M Na2C0............................................. 11.2 The reagents used were all of C.P. grade. The anions studied may be divided into three groups: (1) anions that had little or no effect upon the potential curves—sulphnte, nitrate, and acetate; (2) those that helped to prevent corrosion at low pH only -fuoridc, chloride, bromide, and iodide; (3) those that helped to prevent corrosion at high pH also—phosphate, pcrborate, and chromate. Potential Measurements f The time-potential curves represntative of group 1 are shown in Fig. 1. These are the curves for 0.005 M sulphate ion and their similarity

Jan 1, 1939

By Harold Markus, Gerhard Derge

The introductory paper1 of this series described the potential behavior of tin in sodium carbonate and bicarbonate solutions whose pH ranged from 8.4 to 11.2 and demonstrated that significant and reproducible results could be obtained by proper attention to experimental technique. In examining the corrosion of tin under such conditions, it is desirable to know the effects of anions, aside from carbonate, that are likely to be present in commercial materials packaged in tin. Therefore, in this paper the potential behavior of tin in carbonate solutions to which sodium fluoride, chloride, bromide, iodide, sulphate, nitrate, monobasic phos-phate, dichromate, perborate and acetate have been added will be dcscribed. For most of the additions, solutions containing 0.001 and 0.01 moles of the added material were studied. The experimental procedure was exactly the same as that described in the first paper; the pH of the electrolyte was controlled by adjusting the ratio of carbonate to bicar-l,ol~ate as follows: pH 0.1 M NaHC0............................................ 8.4 2 parts 0.1 M XaHCOr, 1 pa.rt 0.1 M NaZCO?................. 9.5 1 part 0.1 M NaHCOs, 2 parts 0.1 M iVa.,C03. ................ 10.0 0.1 M Na2C0............................................. 11.2 The reagents used were all of C.P. grade. The anions studied may be divided into three groups: (1) anions that had little or no effect upon the potential curves—sulphnte, nitrate, and acetate; (2) those that helped to prevent corrosion at low pH only -fuoridc, chloride, bromide, and iodide; (3) those that helped to prevent corrosion at high pH also—phosphate, pcrborate, and chromate. Potential Measurements f The time-potential curves represntative of group 1 are shown in Fig. 1. These are the curves for 0.005 M sulphate ion and their similarity

Jan 1, 1939

By Jr. W. L . Phillips

The deformation and fracture characteristics of lithium-fluoride single crystals stressed in compression at room temperature have been studied. In as-cleaved specimens the stress-strain curves were variable; two types of {110} fractures were observed in the vicinity of kink bands. The stress-strain curves of annealed crystals were reproducible; {100} cracks formed which propagated along the (100) and (110) planes. The deformation and fracture characteristics were affected by quenching and X-ray irradiation. STUDY of the mechanical behavior of nonmetallic materials has received considerable impetus in recent years because of the need to overcome the problem of brittleness before the refractory properties of nonmetallics can be fully exploited. Ionic crystals provide a convenient and simplified starting point from which to study the deformation and fracture processes in nonmetallic materials. Early investigations of the mechanical behavior of non-metals were restricted largely to determinations of the crystallographic indices of the cleavage and fracture planes and the glide and twinning elements. Until recently, only occasional systematic studies of the deformation characteristics of non-metals have been made; and investigations of the forces necessary to initiate plastic deformation and the factors which affect the flow characteristics have been restricted largely to studies of sodium chloride&apos;-7 , magnesium oxides-l3 and lithium fluoride. 14-22 Fracture studies on alkali halide and metal oxide single crystals have been limited despite the fact that these materials have a number of advantages for fracture studies. Because they are transparent, the cracks which form can be viewed in three dimensions instead of in two dimensions as in metals. Also, they exhibit stress birefringence under polarized illumination, which enables the internal stress pattern and, therefore, the distribution of dislocations to be examined in the vicinity of the fracture. Early workers1-4 have shown that ionic crystals with a cubic structure fracture in tension along the (100) plane normal to the applied stress. These fractures were brittle at room temperature and propagated very rapidly across the cross section of the crystal. More recently, Stokes, Johnston, and Lil0 have studied crack formation in compressed magnesium-oxide single crystals. They found that the cracks, which were observed after about 3 pct strain, formed in the region of a kink band and lay on conjugate (110) slip planes instead of the usual(100) cleavage plane. Two different types of cracks were noted: stroh23 and secondary. The Stroh cracks did not exist merely on the surface but extended through the specimen in the form of tiny slits. A secondary

Jan 1, 1962

By Maurice Grieves

The great majority of shafts constructed today are still excavated by drilling and blasting, a method which changed very little in over 100 years until the introduction of the mechanical lashing unit and cactus grab by the South Africans, which enabled muck to be removed as fast as massive hoisting systems could handle it and resulted in very rapid rates of sinking. Record breaking month&apos;s performances were achieved at -Hartebeestfontein No. 4 shaft, October 1960-337.1 m; Western Reefs No. 4 shaft, October 1961-340.7 m; and Buffelsfontein eastern twin shaft, March 1962-381.2m. The method was very labor-intensive, requiring a crew of over 60 workers at the shaft bottom during the drill cycle. Safety precautions were strict, but in the drive to achieve rapid advance, cases of personal injury were still somewhat high because of the large number of people engaged in this potentially hostile environment. The South African method, as it came to be referred to throughout the rest of the world, was adopted in the United Kingdom in the late 1950s in a modified form with greatly reduced manpower and nonsimultaneous sinking and lining, which was insisted on by the British Mines Inspectorate. In that instance, it was successfully used to sink the 7.3-m-diam concrete-lined shafts at Kellingley to 770 m depth, with rates of advance of over 90 m/month achieved, a British record at that time. During the sinking of the 1.15-km-deep twin shafts at Boulby potash mine in the UK in 1970, the method was again used, but for the first time ever in Britain exemptions from the mining code permitted the use of crash beams, crash doors, jack catches, and semi-simultaneous sinking and lining techniques. New British shaft sinking records of over 120 m/month were achieved in both shafts. Similar equipment and techniques were used in the early 1970s to sink several deep shafts in Canada, notably Creighton #7 and the Con zinc mine at Yellowknife in the NW Territories. Today, this equipment is standard for deep shafts in the US and the rest of the world. However, with the tremendous escalation in mining labor costs, the impact of health and safety legislation, and environmental regulations, coupled with a very real shortage of miners willing to work in this exposed situation it was apparent that an alternative to the labor-intensive conventional method of shaft construction had to be found. Recognizing the trend is inevitable, one or two major German shaft sinking contracting firms began to take a fresh look at full face boring techniques applied to tunnels and raise bored shafts. The results were most encouraging. Tunnel drivage techniques using moles had developed considerably from Colonel Beaumont&apos;s original channel tunnel machine circa 1880 to the superbly engineered Priestley machine selected to cut the British side in 1975 and the double shielded Robbins Grandori borer on the French side of the English Channel. Full face tunnel machines were being successfully used to drive uphill in inclined shafts in Austria and Switzerland. At Mapprag in Switzerland, the Demag mole drove the first (intentional) vertical transition and curve, and then went on to successfully complete the 730-m-long penstock shaft at an inclination of 35°. In Austria, the Wirth mole drove the Kaprun Glacier ski-lift railcar tunnel at record breaking rates of 457 m/MONTH (best 30 m/d) through green schist at an inclination of 29° for a distance of 3.35 km while the Hydro tunnel at Sarrelli in Switzerland was being driven by the Robbin&apos;s mole at an inclination of 35°. Simultaneously, extremely promising results were obtained using large assemblies of cutter discs on raise borer heads, such as the 4.87-m-diam X 460-m-deep shaft raised by Teton for Jim Walter Resources Inc. Bearing in mind that most mine shafts in the future (unless in exceptionally competent rock) will require some form of lining, and the trend will be toward deeper shafts as the more easily accessible mineral deposits become exhausted, it was seen that normal raise boring had definite limitations in vertical accuracy, in the limitation imposed by the drill string on the available torque that could be applied to the cutter head, and in the risk of collapse of the unsupported shaft rock wall in friable or jointed and fissured ground, since it is not possible to apply any form of temporary support until the permanent lining is being installed. A further problem was the economics of installing a subsequent lining, necessitating setting up a headgear and hoisting arrangement approaching in size that required for conventional drill and blast sinking and lining. Because of the economics, German contractors opted for a phased transition from drill and blast to the full face, rodless, out of the solid shaft mole, by starting off with a down-the-hole shaft boring machine -without a drillstring-but using a pilot hole to get rid of the muck.

Jan 1, 1982

By Subhas G. Malghan

Feldspathic deposits occur widely throughout the United States, but North Carolina, California, Connecticut, and South Carolina accounted for over 80% of the total domestic feldspar output for the year 1973.1 Pegmatites and granites constitute the major feldspar reserves of the United States, 2 and in addition, feldspar is produced as a byproduct by firms whose major products are spodumene and mica. 3 Feldspar flotation is practiced in the United States, Mexico, Finland, Norway, West Germany, Japan, and the USSR. According to the US Bureau of Mines estimates, the production of feldspar in the United States and rest of the world were 704,000 and 2,514,000 t, respectively. Feldspar is principally used as a flux in making glass, pottery, porcelain, enamel, tile, and other ceramic products. In recent years, the domestic feldspar industry is faced with a number of problems. As a result of increased cost of energy and the introduction in 1972 of new legislative programs relating to air, water, and noise pollution, land-use restrictions, and mined-land rehabilitation, the production costs have increased. Apart from the increased cost of operation, an operational problem exists with the feldspar producers in North Carolina, especially those in the Spruce Pine area. This problem is concerned with the use of hydrofluoric acid in the feldspar flotation. Feldspar producers in Spruce Pine, NC, have been discharging process waste water into the North Toe River. The mill waste water contains active fluoride ions. Fluoride in excessive concentrations is undesirable in waters used for drinking. It is stated that water containing 0.9-1.0 ppm fluoride will seldom cause mottled enamel on children&apos;s teeth; and for adults, concentrations less than 3-4 are not likely to cause endemic cumulative fluorosis and skeletal effect. Although the literature on this subject is rather confusing and inconclusive, the inference that concentrations over 4 ppm may affect bone structure is clear. According to the recent Federal Register,4 maximum fluoride level of 1.4 ppm at 79°-98°F is considered to be adequate and safe for the protection of health of the consumers. The EPA and state environmental agencies have accelerated their drive to reduce water pollution on a faster schedule. By 1977, the EPA specifications for maximum contaminant level of fluoride ions in the discharge waters of feldspar milling operatins is expected to be reduced to 2.0 ppm. The other problems of using hydrofluoric acid are the following: toxicity, hazards of handling and storage, and high cost as compared to other inorganic acids (almost 16 times the cost of sulfuric acid). In order to reduce fluoride levels in mill discharge waters, mining companies have taken the following steps: I) Recirculating a part of their mill water. Even though recirculation of mill water seems to be a novel method of reducing fluoride contamination of the discharge water, there are certain operational and handling problems. 2) Conducting research on the treatment of fluorides in mill waste water. The technology of treatment of fluoride ions has received considerable interest in the recent years. A recent research report5 estimates that the cost of fluoride ion removal to meet the present specifications in the feldspar industry is approximately $0.25/t of ore processed, and about $0.50/t of feldspar produced. At the request of the feldspar producing industries in North Carolina, the North Carolina State University (NCSU) Minerals Research Laboratory has taken up a research program directed towards overcoming the fluoride ion pollution problem. After a close study of the operational, technical, and economic aspects of feldspar flotation, it was decided to attempt to replace the conventional hydrofluoric acid process. Conventional Feldspar Flotatin Using Hydrofluoric Acid Since the inception of the feldspar flotation process using hydrofluoric acid by O&apos;Meara2,6 the process has achieved a great commercial success. In the conventional flotation separation of feldspar-quartz, hydrofluoric acid is used to suppress quartz and activate feldspar, and a long chain amine salt (acetate or chloride) is used as a collector. The bulk of amine collectors used in current feldspar operations are applied as the water-soluble acetates of the free-base amines. These products are pastes or waxy solids which are available in a range of acetic acid neutralization levels generally 50 to 100% neutralized. In spite of the problems mentioned in connection with the use of hydrofluoric acid, this process is extremely stable with respect to changes in the process variables. With the exception of a few operations, alaskite and pegmatite are the major sources of feldspar.7 In the flotation treatment of a pegmatite that contains iron-bearing minerals (heavy minerals), mica, feldspar, and silica, a logical order of removal presents itself considering the following:8 1) Mica is readily floated by an amine collector in a pulp pH 3.5. Some iron-bearing minerals will usually respond to amine collector in acid circuit with the mica concentrate. 2) Since iron minerals tend to occur invariably in the feldspar concentrate, it is desirable to remove most of these prior to feldspar flotation. A fatty acid or a petroleum sulfonate collector used in this flotation step in acid circuit will float iron-bearing minerals. 3) Using hydrofluoric acid to maintain pH of 2.5, an amine collector employed in a final step will float feldspar away from silica, usually leaving the latter in the tailing as a high-grade silica concentrate. The problems connected with the flotation separation of feldspar-quartz arise due to the similarities in their chemical structure. Therefore, any reagent system that is likely to succeed in feldspar-quartz separation should have adsorption affinity towards one of the minerals and depression effect towards the other mineral.

Jan 1, 1979

By P. R. Bradley

NO thought had been given to deep level mining at the Alaska Juneau mine prior to 1930, but in that year a prospect winze was started and continued for 1000 ft. vertically below the main haulage or adit level. The point at which this winze was started was selected entirely by the prevailing physical conditions, such as proximity to established workings, convenience, and the presence overhead of a substantial pillar of dimensions sufficient to lo¬cate the sheave wheel and loading pocket. It was, therefore, with some surprise that the unusually high-grade ore found just below the collar of the winze persisted, with certain vari¬ations, to a full depth of 1000 ft. vertically. Likewise this unusually high-grade ore was found to persist on the various crosscuts driven on levels at 200-ft. vertical intervals. To be brief, this deep level work found richer ore than any yet found in the mine over like areas, and inasmuch as the area was sufficient to plan for extensive deep level mining, plans for such work were given extended consideration.

Jan 1, 1936