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By R. J. Teitel

The Pb-U system has been investigated by X-ray, thermal, and microscopic analyses. Two pyrophoric intermetallic compounds were found; UPb3 and UPb. The crystallographic structure of UPb3 is reported. A phase diagram was drawn for the system showing three eutectic and one syntectic reaction. AS a result of the interest in uranium metallurgy, the Pb-U system has been investigated. Practically no quantitative data appears in the literature concerning this system. Chips were machined from bars of high-purity uranium obtained from Ames Laboratory and the lead was 99.9 pct high-purity grade from Bel-mont Smelting & Refining Co. The chips were pickled in a dilute solution of nitric acid, washed in water and then alcohol, and dried prior to use for alloy preparation. The lead was simply sheared from the pig with no chemical treatment. Lead and uranium were placed in graphite crucibles and loaded into an induction furnace. In order to insure good alloy formation, the lead was loaded above the uranium to wash the uranium chips into the melt. After the charge was held at the desired preparation temperature for 15 to 30 min, it was allowed to cool in the crucible. The entire melting operation was accomplished in an atmosphere of helium (double charcoal refined grade with no further treatment). The procedure was to outgas the furnace by first evacuating it to 10-% m Hg, admitting helium to 8 psi gage and sealing the furnace off. An optical pyrometer focused on the charge through a hole in the crucible cover was employed for thermal measurements. Usually a 50° to 70°C correction had to be added to the instrument value. The most suitable alloy preparation temperature range was found between 1220° and 1280°C. The reason for this is explained by the phase diagram, Fig. 7. Above this temperature range two liquids separate preventing alloy formation upon cooling at a reasonable rate. On the other hand, below this range the uranium was coated with a layer of both compounds and the rate of reaction was diminished by diffusion processes. The fastest reaction rate occurred in this narrow range of temperature because only UPb coats the uranium and it evidently does not protect the uranium as well as UPb,. Apparatus and Procedures The development of apparatus and techniques was determined by the peculiar properties of the alloys. All the alloys were pyrophoric, and, consequently, the alloys had to be protected from oxidation by handling them in a dry box or inert atmosphere furnaces. Other operations performed outside of this equipment had to be done as quickly as possible. Thermal analyses were conducted in a furnace and arrangement similar to that described by the author.' Graphite crucibles having a thermocouple well in the bottom were used to contain the prepared alloy, while a helium atmosphere protected the melt from oxidation. The furnace was outgassed by pumping a 10-3 mm Hg vacuum until the furnace had been heated to 400°C. Then helium was admitted and the furnace sealed under 8 psi gage pressure. Chromel-alumel thermocouples were used for thermal analysis and the accuracy of thermal measurements was judged to be k 5°C. At first, an attempt was made to use platinum-platinum-rhodium thermocouples, but evidently lead vapors attack it at high temperatures forming low melting alloys. These lead vapors had direct access to the thermocouple because the graphite crucible was porous. A differential temperature control was used to regulate thermal analyses. The thermal gradient across an alundum tube placed between the windings and the crucible was maintained constant by a controller.

Jan 1, 1953

By Lovell Lawrence

MAGNETITE deposits in the Eastern States have been mined uninterruptedly since pre-Revolutionary War days. The industry, thriving in normal times, was given impetus in all periods of tumult, and continued to advance and expand, until the Lake Superior ores came into production. A period of comparative quiet existed until increased freight rates, together with increased mining costs on Lake Region ores, permitted the magnetites again to compete. This, coupled with World War demands, created unpre¬cedented activity. Producing plants were at their peak, new mines were equipped and put in operation and the industry pushed production beyond the absorption point. Ore stocks were tremendous, internal competition severe, and a great increase in import of European ores brought the industry to a low ebb in 1923.

Jan 1, 1933

By Harry A. Lipsitt, Douglas Y. Wang

A fatigue study in completely reversed axial tension-compression has been perforried on high-purity titanium and on three high-purity alloys of titanium. The alloys each contain approxi7nately 0.75 at. pct of a single interstitial element; carbon, nitrogen, and oxygen, respectivley. The results corroborate a previously published theory which proposed that strain aging under alternating stress was responsible for the fatigue limit behavior of certain alloys. The present data indicate that in these alloys an increasing strain-talline aging effect under alternating stress is provided by oxygen, carbon, and nitrogen, respectively. CURRENT research on the nature of the fatigue limit in metals suggests that the presence of a fatigue limit in metallic materials is a manifestation of strain aging that occurs under alternating stress.lm5 A comprehensive theoretical model based on the above hypothesis has been developed to explain the existence of a fatigue limit.' This model also provides increased insight into several other fatigue phenomena as under stressing, overstressing, and coaxing effects. The theory, as well, provides equal understanding for those cases where no real fatigue limit is observed. Briefly, this theory assumes that the S-N curve for a pure metal is a smooth function of the applied stress, and the effect of adding an element that is soluble (or forms a precipitate) in the pure metal is simply to shift the S-N curve to the right. If the added element confers the power to strain age, the result is a further shift of the S-N curve, this time upward and to the right. Since strain aging is not expected to be a strong function of stress, and since damage per cycle is known to be quite stress dependent, it is to be expected that there will be some limiting lower stress at which the strengthening due to strain aging will balance the damage due to crack propagation. This stress is the fatigue limit. The position of the fatigue-limit knee was thought to be a function of the magnitude of the strain-aging effect on both the finite and infinite life portions of the S-N curve. Although the strain aging hypothesis seems to be reasonably valid for bcc materials,2'6 it needed to be tested for both fcc and cph metals. This report is the first of a series concerning the fatigue-limit behavior of titanium with varying amounts of the interstitial solutes (C, N,, and 4) that are known to cause static strain aging in titanium. Yield-point effects have been reported for polycrys-talline high-purity titanium alloys containing either carbon, nitrogen, or oxygen.7'9 These effects were observed at testing temperatures in the range 100 to 300'. In addition yield-point and strain-aging effects have been reported for single crystals of titanium containing 0.1 wt pct C plus N.' These yield points were observed over a wide temperature range, but no room-temperature aging occurred. Aging at 180' was required to cause the return of the yield point. The magnitude of the yield phenomena in titanium containing interstitials is not expected to be as large as is observed in bcc metals because of several factors. Titanium has a very high chemical affinity for oxygen and nitrogen. The thermodynamic stability of solutions of oxygen or nitrogen in titanium is recognized. Lattice parameter measurements of titanium containing arbon, oxygen,1° or nitrogen" show that the "c" parameter is expanded more than the "a" parameter, but that up to about 2 wt pct this results in an insignificant change of the axial ratio 'c/a." Ehrlich" has shown that the sites occupied by interstitial atoms in titanium are spherically symmetrical and therefore a lattice expansion, at a constant c/a ratio, results in a simple dilation of the interstitial site. Such a dilation involving no shear has been shown to react only with edge components of dislocations.13 This causes only a weak pinning action. Shear stresses would be anticipated locally when only one of the two interstitial positions was occupied. The carbon atom will cause a symmetrical distortion of the lattice whereas the oxygen and nitrogen atoms have, in addition, the previously mentioned chemical affinity of titanium for these elements. These factors will result in a considerably smaller reduction of free energy upon the association of interstitial atoms with dislocations, and therefore a much weaker pinning than has been observed for the bcc metals. These considerations would lead to the hypothesis that of the interstitial elements considered here carbon would cause the strongest pinning effect in titanium where the amount of interstitial in solution is constant. This hypothesis will be borne out in the analysis of the present results.

Jan 1, 1962

GWILLIAM H. CLAMER (Philadelphia, Pa.).-About 16,000 tons of tin is used annually in the production of white metals. The real reason for using the so-called genuine babbitt, which is a high-tin base babbitt, perhaps in the majority of cases, is that tin has always been. a high-priced metal and people naturally believe that what they pay a high price for must be good. Mr. Jones has shown that the common metal, lead, is a superior base for most purposes for Which babbitt metal is used. The addition of lead is often looked upon as adulterant to genuine babbitt, and specifications for this reason rigidly restrict the lead content. A sub-committee of the Society for Testing Materials, at the meeting in June, presented tentative specifications on babbitt metal, in which were included twelve formulas, containing from zero to: 20, per cent. of tin, and several containing from 65 and 92 per cent. Babbitts. containing

Jan 1, 1919

By Thomas T. Read

MINING, which is at least twenty centuries old, was at first, and long, wholly a practical art. Little more than two centuries have elapsed since the inception of the idea that general education and a knowledge of natural science would be of advantage to those engaged in the mining industry. Though schools of mining began to develop in Europe early in the eighteenth century the concept of educational preparation for technical conduct of the industry was slow in winning general acceptance in the industry itself. John Hays Hammond, in his autobiography,1 recalls that when he sought employment with a mining company after he had graduated from Yale and Freiberg he had to assure its executive, before being even considered for employment, that he did not consider that he had learned anything about mining. This was as late as 1880. Existence in the industry of a prejudice against education of the academic type is perhaps an explanation why inadequate provision has been made by the mining industry for the continuing education of technical employees after they enter employment, although engineering education prior to engaging in industry has now won general acceptance. I am familiar with the existence of "loop" courses for engineering graduates in metallurgical plants, of schemes for giving mining graduates "practical experience," and of the interest in vocational courses for workmen which sprang up in the period of labor shortage during and immediately following World War I (but which quickly died when the depression of 1921 again made experienced workmen available in sufficient supply), having been chairman of a committee appointed by the Mineral Industry Education Division to make a survey of existing provisions for post-employment training for engineers in our industry. The results of that survey, reported elsewhere, clearly indicate that it is inadequate as to amount; the aim of this paper is to present evidence for belief that it is also inadequate in quality. To avoid becoming too involved, no reference will be made here to post-employment vocational training for workmen, which is a subject differing so much from post-employment education for engineers as to require separate treatment. Neither will postgraduate education for metallurgical engineers be discussed, because a distinction must then be made between training for research work and for plant operation, whereas mining engineers engage almost exclusively in operations. Since the situation in the coal-mining industry has been discussed at several recent meetings, that also will be passed over, and what follows should be taken as a discussion applying exclusively to the metal-mining industry. PROFESSIONAL DEVELOPMENT In the operations field (both in mining and metallurgy) the work to which a beginner is assigned is seldom closely related to previous academic education. The contrast is almost as great as between

Jan 1, 1941

Albin, B. R Billings, Mont. '28 Amster, Nathan L 25 Broad St., New York, N. Y. '28 Bache, Jules S 42 Broadway, New York, N. Y. '28 Barrett, C. P 5338 Harper Ave., Chicago, 111. '28 Bayless, William S Russ Bldg., San Francisco, Cal. '28 Bean, Louis, H 60 E. 42nd St., New York, N. Y. '28 Beatty, Ross J Room 604, 6 N. Clark St., Chicago, III. '28 Benwell, Oswald F Hold Mags. '28 Beymer, Albert S., V.P., Keystone National Bank Pittsburgh, Pa. '28 Blumenthal, Hugo 44 Pine St., New York, N. Y. '28 Boettcher. Charles Ideal Cement Bldg., Denver, Colo. '28 Bowlus, Thomas H., Banker, Pres., Allen County State Bank Iola, Ran. '28 Brown, Colvin B Chamber of Commerce, Washington, D. C. '28 Burt, Maxwell Struthers Southern Pines, N. C. '28

Jan 1, 1934

By Albert E. Wiggin, Frederick Laist

Early ill 1914 it was decided to test, on a fairly large scale, the treatment by flotation of Anaconda slime and mill tailing. For this purpose a standard-type Minerals Separation machine was installed at the Washoe Reduction Works during May and June, 1914. This was followed by the installation of a full-size Callow pneumatic machine plant. Experiments were also made, on a smaller scale, with the Froment, the Towne, the Fields, and the Anaconda flotation machines. The last-named machine was developed at this plant. In addition to the tests made in the standard-type Minerals Separation machine some tests were made using a Minerals Separation machine of the sub-aeration type. During the series of experiments a large variety of oils was tested. Experiments were also conducted using both round-table feed and tailing to determine whether it would be better to displace the round tables by flotation for the treatment of the slime, or to supplement the round tables by flotation of the round-table tailing. A series of tests was also made on the treatment of the mill tailing by grinding followed by flotation to determine the relative merits of flotation and leaching for the treatment of this product. In addition, flotation tests were made on mixtures of mill tailing and slime. The round-table feed referred to above is the total slime from the mill. It contains about 35 per cent. colloidal solids and approximately 90 to 95 per cent. of the total solids will pass through 200 mesh (0.067 mm.). It assays from 2.3 to 2.6 per cent. Cu. The mill tailing referred to above is the total discard from the mill, exclusive of the slime. It is all finer than 2 mm. and about 90 to 95 per cent. will remain on 0.25 mm. It assays about 0.60 per cent. Cu. A brief summary of the experimental flotation results follows:

Jan 1, 1917

By Frederick Laist

I. EXPERIMENTAL FLOTATION CONCENTRATION INTRODUCTION EARLY in 1914 it was decided to test, on a fairly large scale, the treatment by flotation of Anaconda slime and mill tailing. For this purpose a standard-type Minerals. Separation machine was installed at the Washoe Reduction Works during May and June, 1914. This was followed by the. installation of a full-size Callow pneumatic machine plant. Experiments were also made, on a smaller scale, with the Froment, the Towne, the Fields, and the Anaconda flotation machines. The last-named machine was developed at this plant. In addition to the tests made in the standard-type Minerals Separation machine some tests were made using a Minerals Separation machine of the sub-aeration type. During the series of experiments a large variety of oils was tested. Experiments were also conducted using both round-table feed and tailing to determine whether it would be better to displace the round tables by flotation for the treatment of the slime, or to supplement the round tables by flotation of the round-table tailing. A series of tests was also made on the treatment of the mill tailing by grinding followed by flotation to determine the relative merits of flotation and leaching for the treatment of this product. In addition, flotation tests were made on mixtures of mill tailing and slime. The round-table feed referred to above is the total slime from the mill. It contains about 35 per cent. colloidal solids and approximately 90 to 95 per cent. of the total solids will pass through 200 mesh (0.067 mm.). It assays from 2.3 to 2.6 per cent. Cu. The mill tailing referred to above is the total discard from the mill, exclusive of the slime. It is all finer than 2 mm. and about 90 to 95 per cent. will remain on 0.25 mm. It assays about 0.60 per cent. Cu. A brief summary of the experimental flotation results follows:

Jan 3, 1916

By B. Haimson, C. Fairhurst

One of the main functions of rock mechanics research has been to find ways of determining in-situ stresses. Many methods have been suggested, the most significant ones calling for measurements inside bore- holes. These methods usually employ some instrumentation for the purpose of measuring hole deformation. Several years ago, a new method was suggested by Scheidegger,l based on previous work by Hubbert and Willis.2 It was the method of "hydraulic fracturing," which had been introduced by the oil industry in 1948 for the purpose of oil-well production stimulation. Basically, hydraulic fracturing consists of sealing off a section of a borehole, pumping in a fluid, and pressurizing it until fracture occurs. If pumping is continued vigorously, the fracture is opened up and extended. In an oil field, such an artificial fracture increases the overall permeability of the formation and usually enhances production. During the entire operation, the variation of pressure with time is ordinarily recorded. Hubbert,2 Scheidegger,1 Kehle,3 and others have shown that the recorded pressures can be theoretically related to the magnitudes of the principal in-situ stresses; the orientation of the fracture can often be used to determine the direction of the principal stresses. The advantage of hydraulic fracturing over the present in-situ stress determination methods is simplicity: no sophisticated instrumentation is required inside the borehole; hence, the stresses can be measured at any depth. Moreover, if the formation is impermeable to the fracturing fluid, no elastic constants of the rock are required in calculating the stresses, a

Jan 1, 1970

By G. Richards Gwinn

THE mineral graphite has been known for hundreds of years and was first used commercially as a coloring agent. Its true identity, however, was not recognized until the end of the eighteenth century and its commercial development did not become extensive until near the close of the nineteenth century. The common names for this mineral are graphite, plumbago, and black lead; others less frequently used are potelot, crayon noir, carbo mineralis, and kish. Graphite was named by Johann Gottlieb Werner in 1789 from the Greek word graphein, to write, and this name was applied primarily to the large crystalline, flake variety. Plumbago is a trade term used primarily for massive graphite as found in Ceylon. Black lead is also a trade term and, like plumbago, is based upon the idea that prevailed throughout the Middle Ages that graphite was a form of lead, or at least contained that metal. Graphite is a soft, black, unctuous form of carbon that crystallizes in the hexagonal system with rhombohedra1 symmetry. It occurs occasionally in six-sided tabular crystals but usually is found in foliated masses, minute disseminated scales, or earthy lumps. It has perfect basal cleavage, is gray to black, has a metallic luster and a gray streak. The specific gravity is 2.1 and hardness is 1 to 2. It is opaque even in finest particles; extremely resistant to the action of acid or heat; and a good conductor of both heat and electricity. Graphite may be separated into three classes: ( ) natural, (2) manufactured (which is sometime called artificial), and (3) colloidal. Natural graphite is divided into two classes, "crystalline" and "amorphous." Crystalline graphite may occur as flake, lump, chip or dust. Amorphous graphite is a commercial term only, as all graphite is crystalline, but grades in which the individual grains cannot be distinguished are classified by the trade as amorphous. Natural mixtures of crystalline and amorphous occur in all proportions. The term "artificial graphite" is a misnomer; "manufactured graphite" is a better term, because it actually is pure crystalline graphite,

Jan 1, 1949

By William Fink

ALTHOUGH age-hardening in an aluminum-base alloy containing magnesium was observed by Alfred Wilm1 as early as 1911, it was not until 1919 that a theory of the mechanism of age-hardening was proposed. Merica, Waltenberg and Scott,2 studying the age-hardening character-istics of Duralumin at the National Bureau of Standards, came to the conclusion that age-hardening of this alloy is caused by the precipitation of CuAl2, which is less soluble at the aging temperature than at the solu¬tion heat-treating temperature. It was postulated that the initially precipitated particles were of fine colloidal dimensions but that they gradually grew in size. Maximum hardness was assumed to be attained when the particles reached a critical size. This theory was at first received skeptically, since it was a widely accepted view at that time that the solid solution state should represent the hardest state of an alloy. Shortly thereafter, Jeffries and Archer proposed their well-known "slip interference theory."3 They suggested that age-hardening was accomplished by the precipitated particles acting as keys interfering with slip along crystallographic glide planes. They showed that this mechanical theory led directly to the assumption that maximum harden-ing would be produced by particles of a critical size, which they suggested would have a diameter approximately 10 times that of the aluminum atom. This contribution amplified and explained so rationally the age-hardening theory of Merica, Waltenberg and Scott that wide accept-ance resulted.

Jan 1, 1939

By Harold Rabling

The following notes are taken from results obtained on a standard 25-ft. Hancock jig1 tested during regular operation in the Bonne Terre mill of the St. Joseph Lead Co. The object of the tests was to determine the conditions for most effective work, and the nature of products that could be made. The material treated was sized between 9-mm. and 2-mm. round-hole screens, and was constant throughout the experiments. Three products were made, concentrates from the first three hutches, middlings from the fourth and fifth, and tailing from the sixth. The middlings were crushed in one pair of Allis-Chalmers Style B, 30 by 14-in. rolls, and elevated with the original ore to the 2-mm. screens, oversize of which formed the jig feed. While this arrangement was very simple, it gave rise to undesirable crowding of the circuit. Table 1 shows tonnage and assay values of the jig feed and products at the beginning of the experiments, and brings out the excessively large amount of middlings, comprising 63.3 per cent. of the total material fed to the jig. The rolls, being heavily overloaded, did very little crushing, a screen analysis of the product showing that only 27 per cent., or 128 tons, was crushed fine enough to pass to the tables. The remaining 347 tons returned to the jig with 400 tons of original ore. At .times, this overcrowding became much worse, and the tonnage in circuit grew to enormous proportions. It became imperative

Jan 1, 1918

By H. W. Morse

MANY of our largest copper deposits contain both sulfide and oxidized copper minerals. The large porphyry mines, with a total copper content of from 1.3 to 2.0 per cent., send to their mills ore with an oxide content of from 0.2 to 0.4 per cent. While the recoveries of the sulfide minerals are considered satisfactory, using modern flotation practice, the recovery of the oxi- dized portion of the copper is small; better recoveries of oxidized copper were made before flotation methods were adopted. Beside the ores containing copper mainly as sulfide, with a small amount of oxidized copper,, many of the large porphyry mines have oxide orebodies, in which the propor-tion of non-sulfide minerals is so high that 2 present methods of treatment are ineffi-cient. In some of the well-known ore-bodies in the Miami-Inspiration district the copper occurs about equally in sulfide and oxidized forms; and the mixing of minerals is complete throughout the ore-body. There is no possibility of mining the sulfides and the oxides selectively. At the New Cornelia mine, however, the oxide, and sulfide ores are sharply separated, per-haps by an ancient water level, so that the oxide ore may be mined and treated in a plant built for that purpose, and the under-lying sulfide ore may be left for treatment in another plant. If copper is to be made from an ore having a total content of 1.5 per cent., it must be concentrated or removed from the ore by some. hydrometallurgical method. Flotation is generally successful for the sulfide minerals and flotation after filming with sulfide seems to work in many cases on the pure carbonate minerals. Callow has given an extensive report on the results of "sulfidizing" flotation on the ores of the. Magma mine.1 Where such ?a 'method can be applied, it ?may be, the best

Jan 9, 1922

By W. R. Hibbard

The term lineage was first introduced by Buergerl to denote dendritic branches, grown from a crystal nucleus during solidification from the liquid, with imper- fections in alignment of the order of 10 : to 10-4 cm. These imperfections are associated with distortions of the dendrites caused by the subsequent solidification of the inter-dendritic filling and are illustrated in Fig I. Buerger etched zinc single crystals made by the Bridgman3 method to develop this dendritic pattern and show lineage microscopically. Since maximum crystal growth in face-centered cubic metals occurs along the [IT] directions,2 lineage would appear in copper as small deviations of dendritic branches from these directions. Elam4 and others5"8 reported etching effects resulting from coring along the cube face traces of various copper alloy crystals. These traces were used by Samans8 to orient single crystals. Williamson9 noted a "lined structure (in alpha brass single crystals) consisting of an ordered arrangement of etch pits" which were probably traces of {IOO} planes but somewhat uncertain because they were never straight (that is, apparently lineage). Greningerl1 described the distortion and multiplicity of Laue spots in back reflection X ray photograms of copper single crystals showing lineage. The present investigation -includes metal-lographic, X ray, and property studies of lineage in large grain and single crystal specimens of copper. Preparation of Specimens specilnens 10 in. long 35 1/2 in. diam of oxygen-free copper (o.F.H.c.) (99.985 pet) were' melted vertically in graphite crucibles under an atmosphere of commercial nitrogen purified through a gas train including sulfuric acid, potassium chloride, magnesium chiorate, hot copper chips and phosphorus pentoxide. After a temperature of 1200°C had been maintained for 1/2 hr, the furnace was turned off and the specimens cooled at a rate of about 150°c an hour' This method of direct solidification was used by Greningerlo to produce single crystals with marked lineage and in this investigation produced a fair yield of single crystal specimens in

Jan 1, 1949

By W. R. Hibbard

The term lineage was first introduced by Buergerl to denote dendritic branches, grown from a crystal nucleus during solidification from the liquid, with imper- fections in alignment of the order of 10 : to 10-4 cm. These imperfections are associated with distortions of the dendrites caused by the subsequent solidification of the inter-dendritic filling and are illustrated in Fig I. Buerger etched zinc single crystals made by the Bridgman3 method to develop this dendritic pattern and show lineage microscopically. Since maximum crystal growth in face-centered cubic metals occurs along the [IT] directions,2 lineage would appear in copper as small deviations of dendritic branches from these directions. Elam4 and others5"8 reported etching effects resulting from coring along the cube face traces of various copper alloy crystals. These traces were used by Samans8 to orient single crystals. Williamson9 noted a "lined structure (in alpha brass single crystals) consisting of an ordered arrangement of etch pits" which were probably traces of {IOO} planes but somewhat uncertain because they were never straight (that is, apparently lineage). Greningerl1 described the distortion and multiplicity of Laue spots in back reflection X ray photograms of copper single crystals showing lineage. The present investigation -includes metal-lographic, X ray, and property studies of lineage in large grain and single crystal specimens of copper. Preparation of Specimens specilnens 10 in. long 35 1/2 in. diam of oxygen-free copper (o.F.H.c.) (99.985 pet) were' melted vertically in graphite crucibles under an atmosphere of commercial nitrogen purified through a gas train including sulfuric acid, potassium chloride, magnesium chiorate, hot copper chips and phosphorus pentoxide. After a temperature of 1200°C had been maintained for 1/2 hr, the furnace was turned off and the specimens cooled at a rate of about 150°c an hour' This method of direct solidification was used by Greningerlo to produce single crystals with marked lineage and in this investigation produced a fair yield of single crystal specimens in

Jan 1, 1949

By R. T. Moolick, John E. Neill, O&apos

In selecting a particular stripping method the ultimate aim is the removal of material at the least possible cost. Accomplishment of this goal requires the careful consideration of many factors including geologic and topographic information, proximity of the stripping operation to waste disposal areas, possible problems of land reclamation, types of suitable equipment available, and auxiliary equipment requirements. 4.2-1. Selection of Stripping Methods. The size of an orebody and the distribution of values within that orebody normally will limit the variety of economical stripping methods which need to be considered. Much may depend upon the selectivity required in the mining due to the relationship between ore and overburden, as well as the character of the overburden itself. The following factors concerning the geologic nature and environment of an orebody, as well as the production requirements, must be determined before any selection of equipment is made: 1. The size of the orebody and distribution of the values within that orebody. Is the ore massive or scattered, bedded or disseminated, thick or thin? 2. The nature of the overburden to be removed. Is it a hard dense rock, bedded rock (thick or thin), friable material, earth, sand, elay, marsh, etc.? 3. The character and significance of geologic structures (fractures, faults, shear zones, etc.) associated with the ore occurrence. Are there water bearing formations with resulting water disposal problems? 4. In considering the nature of the overburden, including its alteration products, the physical or chemical conditions which, when combined with anticipated climatic conditions, may render certain equipment inoperable during unfavorable seasons.

Jan 1, 1968

By Peter B. Scotland

The mines of the Arizona Copper Co. are situated in the Morenci-Metcalf copper district in southeastern Arizona. This copper-bearing district covers a triangular mountainous area of about 3 square miles, rising abruptly from the gravel plateau of the surrounding country. In this area, an immense intrusion of porphyry lias displaced, shattered, and engulfed the shales, limestones, and quartzites formerly bedded on the basal granite. Outcrops of oxide ore were discovered in 1873, and these surface ores were found to connect in depth with large bodies of high-grade oxide ores in the limestones and shales. The mining of these high-grade ores continued until about 1893, when their rapid exhaustion led to the discovery and exploitation of the low-grade sulphide ores in the adjoining porphyry. Methods of concentration were then devised and the low-grade ores finally rendered profitable. The Arizona Copper Co. and the Detroit Copper Mining Co., operating in the same district, were the pioneers in the successful development of the low-grade "porphyry" properties of to-day. The largest mines of the Arizona Copper Co. are the Humboldt and Clay at Morenci, and the Coronado, Metcalf, and King at Metcalf. These mines produce about 4,000 tons daily of concentrating ore containing from 2.5 to 2.8 per cent. copper. The topography of the country is very rugged and mining operations are conducted principally through adit levels. A few of the mines are opened by shafts, the deepest being 1,100 ft., in the Coronado mine. Ore Occurrence The low-grade sulphide ore occurs as: (1) disseminated deposits in the main stock of quartz porphyry; (2) lode deposits in fault fissures in granite. The high-grade oxide ores were found as tabular deposits in limestone and shale close to contacts with porphyry dikes. Low-grade oxide ore formed the outcrop of some of the sulphide orebodies; the majority of the outcrops, however, were barren.

Jan 1, 1915

By Harold Rabling

THE following notes are taken from results obtained on a standard 25-ft. Hancock jig 1 tested during regular operation in the Bonne Terre mill of the St. Joseph Lead Co. The object of the tests was to determine the conditions for most effective 'work, and the nature of products that could be made. The material treated was sized between 9mm. and 2-mm. round-hole screens, and was constant throughout the experiments, Three products were made, concentrates from the first three hutches, middlings from the fourth and fifth, and tailing from the sixth. The middlings were crushed in one pair of Allis-Chalmers Style B 30 by 14-in. rolls, and elevated with the original ore to the 2-mm. screens, oversize of which formed the jig feed. While this arrangement was very simple, it gave rise to undesirable crowding of the circuit. Table 1 shows tonnage and assay values of the jig feed and products at the beginning of the experiments, and brings out the excessively large amount of middlings, comprising 63.3 per cent. of the total material fed to the jig. The rolls, being heavily overloaded, did very little crushing, a screen analysis of the product showing that only 27 per cent., or 128 tons, was crushed fine enough to pass to the tables. The remaining 347 tons returned to the jig with 400 tons of original ore. At times, this overcrowding became much worse, and the tonnage in circuit grew to enormous proportions. It became imperative

Jan 8, 1917

By B. Tani, K. Anderson, I. Johnson, R. Schablaske

INVESTIGATION of the various rare earth-cadmium binary systems discloses the existence of a compound corresponding to the composition MCd6 in all systems save the La-Cd system. Lattice constants for all of the MCde compounds, except LaCd6 which apparently does not form, and PmCd6 whose synthesis was not attempted, are also recorded herein. Iandelli and Ferro 1 report the existence of the compound CeCd6. No additional information, structural details, and so forth are given. Elliott and Lemons2,3' have measured the vapor pressure of cadmium over CeCd6 and have calculated the activity of cadmium in solid CeCd6. These authors find that CeCd6 exists over a composition range from 5.967 to 6.098 (Cd:Ce ratio) at 584oC, and from 5.971 to 6.118 at 639°C. The following is an excerpt from the paper by Elliott and Lemons: 2 "Recently Mr. F. H. Ellinger of this laboratory has indexed an X-ray diffraction powder pattern of CeCd6.00 which we had prepared by gas phase reaction. The compound has a primitive cubic unit cell with a = 15.783 + 0.001A Based on the volume of the cubes surrounding an elemental cerium or an elemental cadmium atom, Mr. Ellinger finds room for 24.10 CeCd6 formula units in the CeCd6 unit cell; similar calculations based on CeCd2 and CeCd11 yield 24.18 formula units per unit cell. The presence of 24 CeCd6 units per unit cell seems probable with an X-ray density of 8.255 grams per cubic centimeter. The most one can say about in-terstitial~ is that there appears to be room in the crystal even at room temperature." Measurements of the solubility of the rare earths in liquid cadmium4 led to the discovery of GdCd6,

Jan 1, 1964

By H. R. Shidel

This paper summarizes the results obtained from the preliminary cementing of wells in an effort to cut off the bottom water. The object of this work was two-fold: (1) To prevent the oil sand from becoming flooded. (2) To plug off bottom water, thereby preserving the individual well and reclaiming production. Valuable suggestions and help have been given by the following named: Messrs. Kyle and La Velle, of the U. 8. Bureau of Mines; Magnolia Petroleum -Co.; Freed Oil and Gas Co. The cementing work was carried out under the personal supervision of L. J. Snyder. In an unpublished paper on the "Water Problem in the Augusta Field," 5. K. Clark reaches the following conclusions: (1) That the great amount of water present is bottom water, occurring in the Varner sand, the main producing or the 2500-ft. horizon, (2) That the only striking connection between structure and water is in .the area of the marked fault on the Ralston, E. C. Varner, and F. Varner leases in sections 8, 9, 16 and 17. (3) That the oil occurs in porous streaks, generally separated by finegrained, well cemented sand, which is barren. Possibly two or three such pay streaks may be found. That under a pay, fine-grained sand occurs, which is presumably barren at the time of drilling, but soon reveals water. The writer takes partial exception to the last point, because well defined shale, slate, lime, or hard sand breaks have been encountered in a great many cases, separating the pay streaks under which water is often found. This is not an invariable occurrence, as cases have been noted when the oil has been followed immediately by water in the same stratum. In an effort to overcome the water menace, the following methods of plugging were tried: (1) Plugging with wood, lead, and limit plugs. (2) Plugging with sand pumpings.

Jan 1, 1920