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By Benjamin N. Webber

THE peninsula of Nicoya contains virtually all of the known manganese deposits of Costa Rica. These are south and west of the Tempisque River, which flows across the peninsula near its juncture with the mainland. This peninsula forms the westernmost part of the province of Guana¬caste, which is the northern of the two Pacific Coast provinces of Costa Rica. The larger villages are connected by ox-cart roads and trails. The area may be covered on horseback without difficulty except during the rainy season, when rivers are in flood and difficult to ford. This is particularly true of the Rio Seco-Guayjiniquil area, where there are no inhabitants and few open trails through the tropical jungle. Santa Cruz and Sardinal are served by the Taca Airlines, two planes a week from San Jose and Puntarenas. The port of Puntarenas has excellent loading facilities but none are available nearer the manganese districts; there ore must be lightered to vessels standing offshore. PHYSIOGRAPHY In Costa Rica there are three physiographic divisions: (I) the central plateau (Mesa Central), a somewhat dissected lava platform upon which are superimposed volcanic peaks, some of which are still active; (2) the Atlantic lowlands and (3) the Pacific lowlands. The peninsula of Nicoya and the larger part of the province of Guanacaste lie within the Pacific low lands. The term "lowland" indicates relation to the central plateau, as the peninsula of Nicoya is largely mountainous. The mountains of Nicoya form the southern extremity of a range of low hills, which are almost continuous along the Costa Rican coast to the Nicaraguan border. The coast line shows evidence of subsidence. The Gulf of Nicoya obviously is the drowned valley of the Tempisque River. The west coast of Nicoya shows many rocks, shoals, bays, inlets and small islands as evidence of a sea encroachment. The altitude of the manganese deposits ranges from 0 to 800 ft. Topography is of the mature type of wide valleys and low ,hills, often with abrupt slopes. The climate is tropical and humid; rainfall of 125 in. falls largely between Sept. I and Jan. I. Vegetation often is very dense, the Rio Seco-Guayjiniquil area being truly tropical jungle, containing many hardwoods. HISTORY AND PRODUCTION The production of manganese ore in Costa Rica apparently dates from the first World War. It reached a peak of about 10,000 tons in the year 1919, then declined rapidly. Evidence of this period of prospecting has rotted away or been swallowed by the jungle. The war now in progress apparently revived the interest in Costa Rican manganese and has encouraged further prospecting. Deposits long known have been redenounced and trails have been cut through the jungle to them. Many new deposits have been discovered in the last

Jan 1, 1942

By R. I. Jaffee, J. G. Dunleavy, W. Hodge, H. R. Ogden

Early in 1946, at the instigation of the U. S. Army Signal Corps, the authors made an extensive survey of the available literature covering high-strength, high-conductivity alloys. For the purposes of the Signal Corps, the minimum tensile strength to be considered was 150,000 psi, together with at least 50 pct IACS conductivity. No single alloy was found to be in production, or mentioned in the literature, which had this combination of properties. The constitution diagram for the iron-copper alloys is not well established in the respect to the two-liquid region. Fig I, taken from the 1939 Ed. of the ASM Metals Handbook, shows a two-liquid system existing above the liquidus temperature, but disconnected from it. Although Ruer and Fickl and Ruer and Goerensz definitely established the fact that two liquid layers could occur in the system, Ruer3 was not convinced that the line of immiscibility was closed in the center. Maddocks and Claussen4 found no liquid immiscibility at temperatures up to 157oOC in alloys containing almost no carbon. Although the diagram would indicate age hardening of the copper-iron alloys is possible, Hanson and Fords found that little hardening effect could be obtained. However, Gordon and Cohen6 reported that the response is better if the quenching is very efficient. Although iron has a potent effect on the conductivity of copper, Hanson and Fords have shown that, when hot-rolled copper-iron alloys are aged at 1200°F, the electrical conductivity decreases sharply with iron contents up to 0.2 pct Fe, and then levels off at conductivities between 60 to 70 pct IACS with compositions to 2.1 pct Fe. They also found that aging did not increase the tensile strength, although increasing iron content gave a moderate improvement in strength. High-strength copper-iron alloys, usually containing about 60 pct iron, had been reported by Smith and Palmer.7 They found that an alloy containing 56.4 pct copper, 0.21 pct magnesium, balance iron, would give a maximum tensile strength of 170,000 psi and an electrical conductivity of slightly over 35 pct IACS. The alloy could also be processed to have I50,000 psi tensile strength, and about 41 pct I.\CS conductivity. Decreasing the iron content increased the electrical conductivity, but the long mushy range during freezing of the alloy containing 10 to 20 pct iron made the production of good castings difficult. In spite of the difficulty encountered by Smith and Palmer with alloys of around 20 pct iron, it was decided to make a rather complete investigation of this type of alloy. As a result of this investigation, a method of alloying and fabricating copper alloys containing 10 to 15 pct iron was developed

Jan 1, 1949

Discussion of the paper of K. Huessener, (Trans., vol. 53, pp. 402 to 4333, and of the papers of Linn Bradley, H. D. EGbert and W. W. Strong, pp. 303, 319. R. J. WysoR, So. Bethlehem, Pa. (communication to the Secretary*). —At our plant (Bethlehem Steel Co.), we have had several Bradshaw burners under course of construction and erection for some time, but up to the present we have not had opportunity to put them in service. I regret that I can not take part in the discussion with some actual results from these burners. Mr. Huessener properly emphasizes the importance of obtaining the highest combustion temperature practicable in boiler practice, which demands a near approach to perfect combustion conditions. The ideal burner is the one which, while meeting the various mechanical requirements, fulfills the above condition under a wide range of gas pressure. The question as to the relative value of hot raw gas and cold washed gas for boiler use is a very interesting one. I think that in the past the importance of low temperature of washed gas sometimes has been overemphasized. Mr. Huessener has pointed out that so far as temperature is concerned, no advantage accrues in washing gas below 100" F. In many plants, there is a notable operating economy in using furnace cooling water, which is appreciably warmer than the supply water. However, in a given type of washer, other conditions being constant, the lower the exit gas temperature the lower will be the dust content; this is equivalent to saying that the more washing water is used, other conditions being constant, the lower will be the dust content of the exit gas. For each type of washer there is a certain desired average temperature difference between inlet water and exit gas, concomitant with known average dust and moisture contents, and with economical operation. With the present tendency toward smaller stove checkers, it is generally agreed that gas for stove use should be cleaned to a dust content of 0.20 grain or less. The method employed and extent of gas cleaning are clearly problems for individual furnace plants. As a general proposition, wet washing is decidedly more attractive for furnaces smelting soft, fine Lake ores than for those reducing chiefly hard, lumpy ores, such as the foreign and domestic magnetites. In the former case the average moisture content of the gas is probably 35 grains per cubic foot, the dust content is relatively high and the top temperature relatively low. In our plant, the ore mixtures consist almost exclusively of hard magnetites. The average dust content of the gas leaving the dust catcher will average only about 2 grains and the moisture about 12 grains per cubic foot, corresponding to saturation at about 83" F. The temperature is fully 100" F. higher

Jan 1, 1917

By A. A. Watts, R. I. Jaffee, F. C. Holden, H. R. Ogden

Hypoeutectoid Ti-Cu alloys are responsive to heat treatment, and considerable variation of mechanical properties may be produced by transformation of the ß phase. Control of cooling rate, isothermal transformation, or quench tempering determine the transformation structure and properties. The transformation products are similar to those of carbon steel. THE equilibrium diagram for the Ti-Cu system has been studied by various investigators, and the most recent diagram is that determined by Jou-kainen, Grant, and Floe.' The titanium-rich portion of this diagram is reproduced in Fig. 1. The alloy compositions and annealing temperatures used in this work are shown. The Ti-Cu alloys containing up to 17 wt pct Cu are representative of an active eutectoid alloy system. Joukainen et a1.l have stated that ß phase cannot be retained on quenching and this has been confirmed in the present work. The similarity between the Ti-Cu system and the Fe-C system is evident and, as will be shown later, many of the transformation products appear to have similar microstructures. Heat treatments in this program were designed to produce the structures of primary interest for study and determination of mechanical properties. Experimental Procedures Preparation of Alloys: Five ½ lb ingots, ranging in composition from 0.8 to 6.83 pct Cu, were prepared by double arc melting in an atmosphere of high purity argon. Titanium melting stock was obtained from high purity iodide titanium, and copper additions were made from copper wire clippings. Segregation was reduced by inversion melting, in which the once-melted ingots were inverted in the crucible and remelted. The double-melted ingots were forged at 1600°F to ¾ in. diam rods, with both heating and forging operations being carried out in air. Surface scale was removed by grit blasting and grinding, after which the forgings were vacuum annealed at 900°C. The alloys then were swaged to ¾ in. diam rod at 750°C and test specimens were cut from this material. The vacuum annealing operation was to remove dissolved hydrogen, which is commonly present in the iodide titanium as-received. Although vacuum fusion analyses were not obtained for all these alloys, past experience indicates that the 6 hr treatment with a limiting pressure of 10- to 10-5 mm of Hg is sufficient to reduce the hydrogen level to 10 to 30 ppm. Vacuum fusion analysis of the 0.8 pct Cu alloy showed 19 ppm of hydrogen. In addition to the five hypoeutectoid alloys, three 15 g ingots were prepared with nominal copper additions of 9, 10, and 11 pct. Fabrication procedures were similar, except that these alloys were rolled to 0.040 in. sheet. Microstructure specimens only were obtained. Table I shows analyzed compositions and fabrication temperatures for these alloys. Heat Treatments: All heat treatments were made in potentiometer-controlled, resistance-wound tube

Jan 1, 1956

By J. D. Hanawalt, C. E. Nelson, J. A. Peloubet

THE subject of the salt-water corrosion resistance of magnesium alloys is somewhat like that of the pitting of stainless steels, in that it involves a relatively small percentage of the applications but receives a much greater proportion of the publicity. Actually magnesium alloys are in use in many exterior applications as well as interior, with no trouble from corrosion. Magnesium and its alloys have a striking stability against atmospheric attack, being far superior to iron. Specimens exposed unprotected to atmospheric weathering for 10 years show only a superficial surface-film formation. The basic nature of magnesium and of its important alloys is that they are also resistant to the attack of salt water even in an unprotected state, giving substantially no loss in weight after one year of alternate immersion in 3 per cent NaCl solution (Fig. I). This basic behavior is often masked because of the extreme sensitivity of these alloys to certain impurities and combinations of impurities. It is known, and the subject of increasing emphasis, that higher purity leads generally to greater stability for many materials, nonmetallic as well as metallic. However, a review of the literature on the corrosion factors in magnesium alloys shows that almost all researchers worked with base metal in which metallic impurities varied in uncontrolled amounts. The major factor, that of metallic impurities, probably greatly overshadowed the effects of minor ones such as flux inclusions, nonmetallic impurities, porosity, metallographic state, which these researchers presumed to study. In the present investigation the first observation of interest is that whereas magnesium of commercial purity (99.9 per cent pure) has a corrosion rate in alternate immersion in 3 per cent NaCl solution at room temperature of anywhere from 5 to 100 mg. per sq. cm. per day, the corrosion rate of high-purity magnesium is 0.15 ± 0.05 mg. per sq. cm. per day. The principle followed in the experiments was to add to such base magnesium other elements, singly and in combination, in controlled and known amounts and to observe the corrosion behavior of the resulting alloy. These experiments show the existence of what may be called "tolerance limits" of magnesium and some of its alloys for certain impurities. The extremely small percentages of impurities involved and the sharpness of the corrosion discontinuities appear to be quite unpredictable. In order to carry on this work, it was necessary to develop an analysis technique suitable to the problem. In some cases it was necessary quantitatively to analyze impurities to less than 0.001 per cent. The experimental data to be presented are based on observation of about 5000 alloy specimens and on more than 50,000 quantitative analyses. While the primary purpose of this paper is to present the experimentally obtained data on corrosion rates as a function of composition, and particularly to demon-

Jan 1, 1941

By H. A. Saller, F. A. Rough

Studies of the V-U system have been made to determine the constitutional diagram. The diagram is fairly simple, since no intermediate phases are formed. Additions of vanadium lower the uranium melting point and allotropic transformation temperatures. The maximum solid solubility of vanadium in uranium is 12 atomic pct and the maximum solid solubility of uranium in vanadium is about 4 atomic pct. WITH the advent of high purity iodide vanadium,' it became of interest to study the alloying characteristics of vanadium and uranium. Alloys were prepared covering the entire system and were studied using a combination of metallographic examination and thermal and X-ray analyses. As a consequence of this work, the V-U constitutional diagram was evolved. In order to prepare suitable alloys for equilibrium-phase studies, it is desirable to have the purest possible starting materials. For this investigation, calcium-reduced vanadium, de Boer process crystal-bar vanadium, and good Mallinkrodt Chemical Co. uranium were used. The first work was done using the best vanadium then available, that being calcium-reduced vanadium produced at Knolls Atomic Power Laboratory. Subsequently, the important features of the diagram were checked using alloys made with crystal-bar vanadium produced at Battelle. These checks are in agreement with the earlier work. Analyses of the starting materials are contained in Table I. Only minor amounts of any impurities were present in either the vanadium crystal bar or uranium. Nevertheless, care was exercised in selecting the uranium for the alloys. The procedure followed was to section the stock into suitable pieces for melting, and macroetch each piece. Only those pieces which appeared to be clean by macroetch examination were used for alloying. Experimental Procedure Melting: Alloys with 0 to 50 atomic pct V were induction melted in beryllia (BeO) crucibles under vacuum of 10 microns pressure or better. A number of remelts was frequently required to insure uniformity of the individual ingots. Although no visible reaction between the alloy and crucible was found in any of these operations, the alloys were checked by spectroscopic analysis. Only trace amounts of beryllium were detected in the alloys. Alloys containing 50 to 100 atomic pct V were arc melted in a water-cooled copper crucible under an atmosphere of helium. A tungsten electrode was used. Ingots of 10 to 15 g were produced readily by turning and remelting a few times. Such small ingots were necessary because high purity vanadium was not available in appreciable quantities at this time. After melting, the ingots were examined metal-lographically for segregation and were consolidated by remelting before fabrication was attempted. Spectroscopic analyses showed that only small amounts of tungsten were picked up during the arc-melting process. Fabrication of Alloys: Alloys containing up to 20 atomic pct V could be fabricated by rolling in air at 600°C with 5 min between passes. After each pass through the rolling mill the alloys were returned to

Jan 1, 1954

By Robert B. Fulton

The objective of this chapter is to discuss the interrelationship between industrial minerals and chemical manufacturing. It is intended to supplement rather than duplicate the commodity chapters. Particular emphasis is given to the pertinent chemical element and to market factors. Condensing this broad subject into a few pages of this handbook permits treating only the most important elements derived from industrial minerals. Hydrocarbons, which quantitatively dominate as raw materials for the chemical industry, are omitted, as are the metallic elements and the minerals covered in other "use" chapters such as phosphorous, potassium and nitrogen for fertilizers, and titanium dioxide for pigments. The remaining six elements of major importance are: boron, bromine, chlorine, fluorine, sodium, and sulfur. These elements are treated individually under separate headings. Table I (Jones, 1973) affords an overview of the main industrial minerals, the chemical products derived from them, and end uses of the products. Salt brines have particular importance as raw material sources for the chemical industry. Table 2 (Anon., 1967) is a chart of the chemical compounds derived from four types of brines: (1) Owens Lake-type brines, which are sources of boron and sodium compounds; (2) Midland-type brines, from which bromine, iodine, and chlorides of calcium, magnesium, potassium and sodium are derived; (3) Searles Lake-type brines, yielding boron, bromine, lithium, magnesium, potassium, and sodium compounds; and (4) Silver Peak-type brines, produced mainly for lithium. Market Attributes Some of the important market traits common to industrial minerals used by the chemical industry are listed below. 1. They are international commodities, such as fluorspar and sulfur, which largely move to foreign consumers. 2. Grade, and freedom from deleterious elements are important factors affecting their usability in chemical processes. An example is salt (NaCl) used in electrolysis where ultrapure evaporated salt is required to meet rigid specifications. 3. Purified products take on the characteristics of specialty items and command a distinctly higher price than the basic commodity from which they are derived. 4. In practically all cases, chemical users require some sort of cleaning or beneficiation of the naturally-occurring mineral to bring it to specification, and individual specifications may vary from user to user for essentially the same use. 5. In some instances it is necessary to strike a balance between what the vendor can supply and what the buyer requires, with the result that specifications have to be eased to afford the needed materials in marginal cases. 6. Because they tend to be bulk commodities, low cost for handling and transportation are important and such costs may limit the area from which a chemical user can draw his supply. For example, fluorspar from China and Thailand normally goes to Japan, while South African fluorspar can go either to Japan or to the US. 7. Shipments are usually in bulk and frequently in multiple-car, full-trainload or full-shipload lots to reduce transport costs, which in turn may require large terminal investment facilities.

Jan 1, 1983

By E. J. Haug, M. M. Fine

For several years work has been carried on by the U.S. Bureau of Mines at Rolla, Mo., to develop improved methods of concentrating the oxidized ores of lead and zinc. Various samples have been investigated, and results on some have been published. Details of the progress to date are given in a mineral dressing study now being conducted for an extensive oxidized lead-bearing tract in southeast Missouri, property of St. Joseph Lead Co. These oxidized ores present problems typical of many encountered in modern mineral dressing research in that recovery of very fine particles is of

Jan 4, 1955

By R. P. Carreker, R. L. Fullman, J. C. Fisher

CREEP tests are usually constant load tests. As deformation occurs, the cross section of the specimen changes so as to maintain approximately constant volume. Until necking starts, A _ l0 A0 - 1 where A is the cross-sectional area, 1 is the specimen length, and the subscript o indicates initial values. Thus, during a tensile creep test under constant load, the stress increases in proportion to the elongation. A A, 1, where S is the stress and F the load applied to the specimen.

Jan 1, 1954

Jan 1, 1967

By John Birkinbine

Forty years ago, when the first shipments of iron-ore were made from the Lake Superior region, the supply for the blastfurnaces active at that date was in most cases a local consideration ; the majority of the smelting-plants being close to the oremines. Of those which depended in whole or in part upon ores brought from distances greater than an economical wagonhaul, few obtained supplies by canal or railroad from points 50 miles removed. At the present time the ore-supply is a local consideration for but a small proportion of American blast-furnaces, and 700 miles or more separate a greater num-

Jan 1, 1898

By G. L. Coleman, D. S. Hutton, W. C. Leslie

The occurrence of twins in a iron, generated during cooling through the ?-a transformation, is well established,1-8 but this phenomenon has been nearly ignored during the past 20 years. It is the purpose of this note to call attention to the prevalence of such twins and to illustrate their appearance. The work of paxton7 and Kelly8 has demonstrated beyond reasonable doubt that for Neumann bands (mechanical twins) in a iron the twinning plane is (112) and the twinning direction <III>. The agreement with McKeehan&apos;s earlier work4 on transformation twins indicates that both types of twins in ferrite follow the same twinning law. There is little doubt of this conclusion, but it could be strengthened by a microbeam X-ray determination of the orientation relationship between a single ferrite grain and a transformation twin within that grain, as in the technique used by Kelly8 on Neumann bands. RESULTS AND DISCUSSION Transformation twins, identified by their appearance on a polished and etched section, were found in

Jan 1, 1960

By Forbes K. Wilson

Dick Hunt is known for having said, "Ore bodies are found but mines are made." This was certainly true of the Ertsberg-it was stumbled upon, literally, by a group of mountain climbers, but to develop it into a mine took 12 years of concerted effort. For more than a century, explorers had attempted to penetrate the jungles of New Guinea and climb the snow-covered Mt. Carstensz, named for a Dutch navigator who first saw it in 1620. But the first to succeed was the Colijn expedition which reached the 5030-m (16,500-ft) pinnacle in December 1936 after starting out from the south coast57 days earlier. Members of that expedition were A. H. Colijn and Jean Jacques Dozy, employees of Shell Oil Co., and Lt. Wissel, a pilot in the Royal Dutch Navy.

Jan 6, 1977

By E. V. Potter, E. T. Hayes, H. C. Lukens

Large volumes of hydrogen are liberated at the cathode during electrolytic precipitation of manganese. Most of the gas escapes from the electrolyte, but a considerable amount may be entrapped in the manganese plate. Gas has been observed to escape from manganese melts in puffs that bite at the surface. It has been reported that castings made with electrolytic manganese tend to rise in the molds; for this reason the manganese is often treated to remove hydrogen before the melt is made or it is premelted and used as cast manganese in making the alloys. The effect of hydrogen on the properties of manganese and its alloys is not known, but its effect on iron and iron alloys has been studied extensively.l.2 The close relationship between iron and manganese suggests that hydrogen may have a similar effect on the properties of manganese and its alloys. The purpose of this investigation was to determine the amount of hydrogen or other gases in typical commercial electrolytic manganese sheet and to investigate ways of removing it most conveniently. Apparatus The apparatus used is shown schematically in Fig. I. It consists of a chamber A in which the metal sample is placed, a vacuum or pressure gauge B, volume gauge C, vacuum pump D, hydrogen container E, auxiliary gas chamber F, and furnace G. The specimen chamber was made of two concentric quartz tubes. The outer one, a, connects with the closed gas system and is surrounded by the furnace G. A second tube, b, fits closely inside a and has a small end that projects into the space for the specimen and holds the thermocouple for measuring the temperature of the sample. The inner tube is joined to the outer tube outside the furnace, with rubber tape and sealing wax, to prevent gas leakage into or out of the closed system. This type of specimen container is loaded very easily and can be used several times if molten metal does not come in contact with the quartz. An ordinary mercury manometer B is used to measure the pressure in the system. The volume gauge C is essentially another mercury manometer, but the volume of the column is much larger than normal and the height of the mercury can be varied by raising or lowering the well H. In this apparatus the tube had a volume of IOO C.C. for a 60-cm. length. For larger changes in gas volumes, auxiliary containers F were used to increase the volume of the system by known amounts. Valves were arranged so that these auxiliary containers could be filled from the system and evacuated by the pump as often as necessary to accommodate the increases in the volume of gas in the system. The furnace G, used to heat the samples, was equipped with an automatic temperature controller, which maintained the desired temperatures within ± 5°C.

Jan 1, 1945

By W. H. Porter, M. E. Wadsworth, J. R. Lewis, K. L. Leiter

The oxidation of Cu2S in oxygen and the sulfating of Cu2O in oxygen-sulfur dioxide atmospheres was carried out under a variety of conditions. The oxidation of Cu2S was found to be retarded by entrapment of SO, and O2, which stabilized internal sulfates for long periods of time. The course of the reaction was followed by measuring weight changes and also by SO, evolution. Sulfating of Cu2O was a maximum at ratios of SO, to O2 approximating maximum SO, production. At elevated temperatures SO, was found to increase the rate of oxidation of Cu2 O to CuO even though sulfates did not form. All sulfating reactions followed the parabolic rate law indicating diffusion. MANY studies of the roasting of copper sulfides have been reported in recent years. Diev et al.1 investigated the roasting of chalcocite (Cu2S) in air, and oxygen enriched air. Lewis et al.2 also studied the oxidation of natural and synthetic chalcocite in air and oxygen atmospheres and their studies indicated that the maximum formation of water soluble sulfates occurred at approximately 450oC. Ashcroft3 reported that oxide production during the roasting of chalcocite resulted only from secondary decomposition of sulfates which were formed as primary products. peretti4 refuted this claim by showing that a layer of Cu2O appeared directly adjacent to the Cu2S during roasting of cylindrical briquettes of cupric sulfide, CuS. The linear advance of the Cu2S-Cu2O interface was used as a measure of the kinetics of the roasting reaction. The reactions proposed were: 2 CuS—Cu2S + 1/2 S2 [4-1] 1/2 S2 + O24 SO2 [4-2] cuzs +3/2 O2 4 Cu2O + SO2 [4-3] cu2o + 1/2 O2—2 cuo [4-4] At temperatures above 663oC, CuO was the only final solid phase reported. Below 663" C increasing amounts of sulfate were found mixed with the CuO. McCabe and Morgan5 investigated the roasting of discs of synthetic chalcocite and reported the following sequence of products beginning at the sulfide surface: Cu2O, a mixture of Cu2O and CuSO4, Cum,, CuO . CuSO4, and CuO. The principal reactions were reported to be: Cu2S + 3/2 O2-Cu2O + SO2 [5-1] CU2O + 2 SO2 + 3/2 O2—2 CUSO4 [5-21 2 CUSO4— CUO . cum, + SO3 [ 5-31 cuo . cuso4—-2 cuo + SO, [ 5-41 Eq.15-11 supports the claim of Peretti, Eq. [4-31, that CuzO is formed directly from Cu2S rather than as a secondary product from a sulfate as suggested by Ashcroft. On the other hand CuO was found to form as a secondary product from the decomposition of copper sulfate and basic copper sulfate, Eqs. [5-31 and [5-41. The formation of sulfates was explained by McCabe and morgan5 to be a direct reaction of Cu2O with 0, and SO, or SO, at distinct regions in which the partial pressures of each were such as to form the sulfate. Thornhill and pidgeon6 roasted both natural and synthetic chalcocite grains in air at temperatures between 420" and 550° C. They found a dense primary oxidation layer in contact with the sulfide. A secondary layer of porous oxidation products was found to expand with roasting time. The oxide products were leached away and the remaining core was studied by X-ray diffraction. The X-ray patterns showed an increased conversion of chalcocite to digenite with time. Digenite,7 a defect structure of cuprous sulfide, occurs naturally as Cu,-,S where x = 0.12 to 0.45, with an average analysis of Cu, ,S. The mechanism of digenite formation was proposed as: Cu2S + oxygen—Cu1-8S + 0.1 Cu2O [6-1] Cuj.eS + oxygen—0.9 Cu2S + SO2 [6-2] It is apparent from the above studies that the oxidation of Cu2S, ultimately ending in CuO, may be divided into ihree general stages (all of which may occur simultaneously): 1) primary oxidation to Cu2O; 2) secondary sulfate formation; and 3) sulfate decomposition. Consequently reactions of O2 and SO, with Cu20 constitute important aspects of the roasting of chalcocite. Virtually no studies have been made regarding sulfating reactions involving Cu,O. Mills and Evans8 noted the effect of sulfur dioxide on the oxidation of copper at low temperatures and low SO, partial pressures. They reported a measurable increase in the oxidation rate of copper when SO2, was present. Interest in the Cu2O-CuO-0, system has been limited predominantly to misciblllty studies and determinations of heats of formation by

Jan 1, 1961

By E. P. Dahlberg, R. E. Reed-Hill

On the assumption that stress or strain relaxation occurs as the result of a thermally activated process, equations are derived relating to tensile experiments that give the strain as a function of the time under the condition of constant stress, and the stress as a function of the time for constant strain. It is demonstrated that if the strain-rate equation i = previously proPosed by Kuhlmann., is used as a starting point, then the relaxation of strain at constant stress may be expressed by the equation c = (-RT/(Y) 1tz tanh (t + is the strain capable of being relaxed at any given instant. Similarly, it is shown that the relaxation of stress at constant strain may be given by a = (-RT/B) In tanh (t + t0)/27, where a is the instantaneois value of the relaxable stress. The fact that these relationships reduce to well-known empirical equations at both large and small values of the stress Or strain is also shozcn. The present theory is shown to agree well with experimental data obtained from tensile elastic aftereffect experiments on a zirconium specimen prestrained at 77 k as to make it strongly anelastic. It is also demonstrated that elastic aftereffect data obtained using torsional specimens ?,Lay agree reasonably well with the equation derived for the case of tension. RELAXATION experiments are often employed as a means of studying metallic deformation mechanisms.&apos; The simplest and most commonly employed techniques involve stress relaxation at constant strain and strain relaxation at constant stress. In general, however, investigations of this nature have been seriously handicapped in the past by a lack of suitable equations giving the time dependence of the relaxing variable over an interval that extends from small strains up into the region where internal-friction experiments become strain-amplitude dependent. This paper presents a derivation of such a set of equations for the case where the time-dependent part of the strain is anelastic or recoverable and the specimens are loaded in simple tension. The relaxation of strain under the condition of constant stress will be considered first. Let us assume that strain relaxation occurs as the result of a reversible thermally activated process that occurs at a number of relaxation centers lying in an elastic matrix. Then, following Kuhlmann,2 we may express the rate of strain relaxation as follows: where C is the strain rate, AFx the free energy of activation of the process controlling strain relaxation, a, the effective or average resolved stress at the relaxation centers, u an activation volume, R the universal gas constant, T the absolute temperature, > a factor with dimensions of a volume that accounts for the strain contribution of a successful operation of a unit process, N the number of relaxation centers per unit volume, and v the Debye frequency. The first term on the right of Eq. [I] represents a strain rate in the direction favored by the stress, while the second term represents the rate in the opposite direction. It is implied in Eq. [I.] that both F and v are symmetrical with respect to the two basic directions of operation of a relaxation process. Eq. [I] may also be written where and S and Q are the activation entropy and activation energy, respectively, of the relaxation process. In the following, A will be considered a constant. This is compatible with a set of experimental conditions where the relaxation rate is controlled by a single basic reversible process in which it may be assumed that the temperature dependence of the product ?Nv is negligible in comparison with the temperature variation of the exponential term. It is also implied that v, 7, and N do not depend strongly on a, . In deriving a relationship for the strain as a function of the time from her equation, equivalent to Eq. [2], Kuhlmann2 chose to consider only the limiting cases where the time was either very small or very large. It will now be shown that it is possible to integrate Eq. [2] to obtain a single equation valid over a wide range of strains if the concept of relaxable strain is introduced. The use of this quantity, which is the difference between the instantaneous value of the strain and the value of the strain at complete relaxation, represents the primary point of departure of the present theory from that of earlier workers. Let us express the effective stress at the relaxation centers in terms of strain. For this purpose we may use the following equation derived by zener3 for the case of strain relaxation at slip bands: where M? and M are the relaxed and unrelaxed moduli respectively, go the applied constant tensile stress, and m an average orientation factor that takes account of the fact that a,, the effective stress at the relaxation center, may not be a tensile stress (i.e., a

Jan 1, 1967

1. List of Manuscripts Seen in America 2. List of Manuscripts Seen in England 3. List of Maps Examined 4. List of Newspapers Examined 5. General Bibliography - Numbered Reference List

Jan 1, 1942

By Charles W. Sweetwood

THE Western phosphate field, virtually ignored for 40 years, has been undergoing a rapid climb to economic importance. Until World War II there seemed to be no reason for developing the phosphate rock region of the Intermountain Empire. But the tremendously increased demand for food production and the needs of many branches of the chemical industry changed all that. Quite suddenly a report made by the U. S. Geological Survey at the turn of the century became important. The survey showed that 60 pet of the nation&apos;s phosphate reserves were in the western phosphate field. Simplot Fertilizer Co. was one of the first to become actively interested in the development of the area. In August, 1945 the company began exploration of the Phosphoria Formation on the Fort Hall Indian Reservation. The result was the Gay Mine, about 18 miles east of Indian Agency Headquarters at Fort Hall, Idaho, developed to supply high grade phosphate rock for processing into superphosphate fertilizer at the company&apos;s Pocatello plant. Six ft of high grade oolitic phosphate rock (ranging from 32.5 to 34.5 pet P2O5) were discovered at the base of the Phosphoria Formation by diamond drilling and dozer trenching. High quality and thickness, plus the fact that the formation lay flat and near the surface made strip and open pit mining possible. In one year of mining, starting June 1946, a total of 53,000 tons of main bed oolitic phosphate rock was hauled to Pocatello for processing into supersulphate. The first year&apos;s operation was in

Jan 1, 1952

By David B. Reger

New discoveries of gas in the southern counties featured the petroleum industry in West Virginia during 194;. Drilling for oil increased slightly over 1944 and a small increase of initial production resulted. Out of 28 wildcats drilled, there were 16 gas discoveries and 12 dry holes. No commercial oil was found in the 28 wells.

Jan 1, 1946

By H. l. Burghoff

THE presence of tellurium in copper and, by inference, in copper alloys, has been considered seriously detrimental and has been avoided. In particular, very small amounts of tellurium have been found to produce red-shortness, although the effects on cold-working and ordinary physical and mechanical properties have not been known so definitely. References in the literature are few, but as long ago as 1881, Egleston1 reported that 0.083 per cent tellurium in fire-refined copper rendered the copper red-short and therefore worthless for hot-rolling. In hot-rolling copper cakes containing this amount of tellurium, he found that fine cracks appeared in the cakes on the first pass through the rolls, the cracks opening further in successive passes. When cold, the metal was said to be tough and malleable. A few years ago, during the course of an investigation in our laboratory on copper-base alloys, it was found that tellurium-bearing alloys could be machined much more freely than similar alloys not containing tellurium. The study was pursued further in this direction, and considerable data were obtained, which indicated that certain tellurium-bearing alloys might have properties of commercial interest. The work eventually led to patent protection,2 a wide range of tellurium-bearing copper-base alloys being covered. This article presents results obtained on the effect of tellurium on the. mechanical properties of three copper-base alloys: commercial bronze (90 Cu, 10 Zn), 1.5 per cent tin bronze (98.5 Cu, 1.5 Sn), and silicon bronze (96 Cu, 3Si, 1 Zn).

Jan 1, 1937