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By Foster Fraas

Almost all minerals show irreversible changes in electrical conductivity after heating in the temperature range 100° to 800° C. This effect can be detected with only a limited number of minerals with the standard ionizing-electrode-type separator, which differentiates between nonconductors and conductors in the single-particle resistivity range of 1011 to 1013 ohms. Tests outside this range with other type separators, such as the static field type, increase the number of minerals with which the effect can be detected to almost all that were tested. Irreversibility may be the result of an alteration of adsorption layers, volatilization of surface cations or anions, or an oxidation or reduction. One example is limonite, which decomposes to hematite and passes through two minima and two maxima in conductivity in the temperature range 100° to 900° C.

Jan 1, 1959

By E. G. King

Existing thermodynamic data for compounds of the rare-earth metals are few in number and often inaccurate because, in the past, it was difficult to obtain samples that were pure enough and reasonable in cost--a situation that is rapidly improving. This paper reports the results of low-temperature heat-capacity and high-temperature heat-content measurements for cerous fluoride (CeF3) and supplies the first such published data for a rare-earth fluoride. The low-temperature heat-capacity data cover the temperature range 51°-298° K. and serve to evaluate the entropy at 298.15° K. The high-temperature heat-content data cover the temperature range 298°-1,799° K., including the temperature and heat of fusion. The results are assembled for ready use in thermodynamic calculations. Cerous fluoride is one of the important intermediate compounds in the production of cerium metal.

Jan 1, 1959

By Bruce I. Thomas

[THIS PAPER, tine of a series on placer ml n in iii Alaska, describes mining methods and gives unit costs at operations where hydraulic and mechanical excavation equipment is used with nonfloating washing plants. The mining methods described were developed during the last 30 years to copy with conditions peculiar to arctic and subarctic regions arid are now used by a large segment of the placer mining industry in Alaska. The operations described have been classified if m ii into three main categories: Those having sluices at a bedrock level, those having sluices above bedrock and those having mobile nonfloating washing plants (dryland dredges). Diesel-powered bulldozers and draglines convey or clevate gold-bearing gravel to the sluices, remove tailings, and strip waste gravel and other overburden. Diesel-powered centrifugal pumps supply water foe sluicing and hydraulic stripping. Detailed descriptions and unit cost arc presented for 14 operations to illustrate the numerous arrangements udder the first 2 categories.]

Jan 1, 1959

By Alfred L. Anderson

Thorite and rare earth deposits in the Lemhi Pass area of southeastern Lemhi County, Idaho, are contained along complex shear and fracture zones and in reopened gold-quartz veins and copper lodes in quartzitic and phyllitic rocks of the Pre-cambrian belt series. Some of the shear and fracture zones are several tons of feet across and comprise broad zones of irregularly mineralized rock. These lodes contain a notable concentration of thorium and rare earth elements along with considerable amounts of barium, .potassium, calcium, iron, aluminum, phosphorus, sulfur, and silicon. The principal minerals are thorite, locally allanite, monazite, xenotime (?), apatite, specular hematite, barite, potash feldspar, occasionally calcite and quartz. Exept for some of 'the specular hematite, barite, reddish feldspar, calcite and quartz, the minerals are not distinguishable without the microscope. The thorite and locally allanite were deposited first, then the monazite and other phosphates, which were in turn followed successively by barite, potash, feldspar, calcite, and quartz. In exceptional cases, deposition of thorite and specular hematite was repeated after the feldspar. Some of the deposits contain several percent thoria, but the average os generally under one percent. The rare earth content is comparable with that of the thoria. The deposits appear to be of hydrothermal origin and are probably related genetically to late Cretaceous or early Tertiary igneous activity, manifested locally by a few dioritie and lamprophyric dikes.

Jan 1, 1959

This report is the 22d in a series summarizing Bureau of Mines research and technologic work on coal and related investigations.2 3/ A summary of work published during 1957 and of work in progress is presented. Details regarding the subjects treated in the publications may be found by referring to articles cited in the footnotes. The objective of the coal work of the Bureau of Mines is to obtain information that will lead to improved production and utilization of coal, thus conserving a most important national asset.4 5/ Though studies of mining methods and exploration of various coalfields ma; contribute directly to improved production, no less so does the work in health and safety. The many problems relating to chemical and physical properties of coal reflect the need for an understanding of these properties for the most effective use of coal in its various fields of application and for the development of new methods of processing coal. Studies of existing and proposed processes of combustion, carbonization, gasification and hydrogenation of coal are necessary for increased efficiency in its use. Engineering service provided by the Bureau is of direct value in the conservation program in preventing waste. Stations where the main coal activities of the Bureau are carried out are shown in the following list:

Jan 1, 1959

By H. D. B. Wilson, D. T. Anderson

"Canadian sulphide deposits generally have characteristic compositions. Metal associations in ore deposits and in igneous rocks are similar.Nickel: sulphur ratios, copper-nickel ratios, and nickel :cobalt ratios in copper-nickel sulphide ores are characteristic for most orebodies. Nickel, as sulphide, is highest in ores associated with ultrabasic rocks, whereas copper is highest in ores associated with gabbros. Cobalt is relatively constant. The metal ratios in copper-nickel ores are due, first, to the composition of the related igneous rock or magma; second, to the partition ratios of the metals into the sulphides when separating from the silicate rock or magma; and third, to the conditions at the time of deposition. Each factor is discussed and the evidence indicates the Frood orebody is a magmatic segregation in place and Falconbridge is an injected sulphide melt. Many Canadian orebodies containing copper, zinc, or lead also have relatively constant compositions. •Copper and zinc are concentrated in gabbro and diorite, and copper-zinc ores in northwestern Quebec are spatially related to gabbros and diorites. The same three factors con-trolling metal ratios in. copper-nickel deposits should control the metal ratios in copper-zinc deposits if the metals come from the gabbro-diorite intrusions.The ratios of base metals in common sedimentary rocks are not similar to the ratios in orebodies. Base metal elements are mobilized during high-grade metamorphism, but much fundamental research is needed before the relation between metamorphism and ore deposits can be established on a sound basis. The distribution of elements in sulphide orebodies suggests that cop-per, zinc, and lead are deposited simultaneously .in relatively constant proportions rather than successively in a paragenetic sequence. Zoning may be due to different ratios of metals being deposited under changing temperature, pressure, and chemical environment, or may be the result of other processes."

Jan 1, 1959

By W. A. Grosh

The Piquette Mining and Milling Co, operates a zinc mine and concentrating mill in the Upper Mississippi Valley zinc-lead district near Tennyson, Wis. The principal ore mineral is zinc sulfide, which occurs in limestones and dolomites of the Decorah formation. Exploration in the district is by churn drilling from the surface. An adit at the base of the ore zone provides access to the mine. A room-and- pillar mining method with irregular pillars is used. Drilling is done with Jumbo-mounted drills. The broken ore is loaded by crawler-mounted front-end loaders into diesel-powered trucks for haulage direct to the mill.

Jan 1, 1959

By W. C. Lacy

THE Cuajone porphyry copper deposit is the northernmost of a group of three deposits in southern Peru controlled by the Southern Peru Copper Corp.-Toquepala, Quelleveco, and Cuajone— all within a 20-mile belt. Although small pockets of high-grade copper oxide ores were worked in the Cuajone area in the 19th century, it was not until 1939 that its potentialities as a disseminated deposit were recognized by 0. C. Schmedeman. An exploratory drilling pro- gram was begun in December 1942 and continued until early 1945. The program was revived in November 1952 and completed early in 1954. Early exploration was by diamond drilling. Later exploration was predominantly churn drilling, with diamond drilling used only for wildcat holes. Along this northwest-trending belt of deposits. which follows the western slopes of the Andean Range, quartz-monzonite has invaded earlier dio-rite intrusives and a series of warped and tilted Cretaceous volcanic flows. Little faulting of consequence has been recognized within the mineralized areas. Sulfide minerals were introduced into all these diverse rocks, and mineralization was followed by erosion, oxidation, and enrichment. In Late Tertiary and/or Quaternary time the entire

Jan 1, 1959

By Charles W. Huggins

DEVELOPMENT of the electron microscope has permitted man to examine many small objects that could not be resolved by the light micro-scope. Diffraction, spherical aberration, and chromatic aberration are the main factors that limit resolution to about two-tenths micron with the light microscope. No matter how perfectly a light microscope is constructed and operated, it cannot possibly resolve points separated by less than two-tenths micron. Rapid development following World War II has produced many electron microscopes capable of 20 A resolution. Fibrous inorganic minerals are well suited for electron microscopic study. Many micrographs of chrysotile have been published, but electron microscopic study of the amphiboles has been somewhat neglected. New techniques in sample preparation have simplified the study of fibrous material. Ultrasonic energy has been very helpful in sample dispersion. This publication contains a representative group of electron micrographs of natural inorganic fibers that have industrial value. These fibers commonly are referred to as the asbestiform minerals. The Bureau hopes that the knowledge gained through electron microscopy and other scientific study of the natural inorganic crystalline fibers eventually will lead to the production of synthetic fibers that will satisfy the requirements of industry.

Jan 1, 1959

By John J. Stokes

Literature on the electrolysis of aluminum from cryolite melts and on the structure of these .melts is surveyed critically. Data on density, freezing point, and other properties are reviewed. Theories of the electrolysis are examined in the light of these data. Two theories are presented which account equally well for the observations. In the early days, the process was thought of as a simple one. The actual mechanisms must be tremendously more complex. This paper is devoted to a rather narrow part of the whole subject, namely, what ions are present in the bath, and by what mechanism the current is carried. Using cryoscopic data, Rolin has determined the following composition for molten cryolite. Na2,AlF 3Na + 3F + AlF [1] He postulates the following equation for the ioniza-tion of alumina at low concentrations Al2O3 Al + AlO2 +O. [2] At concentrations above 0.025M he supposes the ionization of alumina to proceed as follows Al2O3 AlO + AlO2. [3] Rolin's mechanism of electrolysis for the more concentrated solution in Eq. 3 is as follows. The AlO' ion migrates to the cathode. where it is dis- charged, giving metallic aluminum and 0' ions which migrate to the anode. The AlO2- ion migrates to the anode, where it is discharged, giving Al ions and oxygen which reacts with carbon to form CO2 In the case of the extremely dilute solution in Eq. 2 the Al ion migrates to the cathode and the AlO2-and 0 migrate to the anode as before. Another possible mechanism for the electrolysis follows. Ionization of Cryolite Na3AlF4 = 2Na + 2F + NaAlF, Na + AlF-AlF+Na + F [4] Addition of Alumina 2Na2AlF+ 2AL2O4 6Na + 3A12O3F4 [5a] Al2O2F 2AlOF2 [5b] Cathode Process AlF, + 3e+ 4F + Al. [6] Anode Process AlOF2 + 2F AlF1 + 1/20, + 2e or A12O2F + 4F-2A1F; + 0, + 4e. [7] Although both Rolin's and the present mechanism of the Hall process may be qualitatively satisfactory, present data are not adequate for quantitative tests of the theories.

Jan 1, 1959

By Donald T. Delicate

Since the discovery of uranium in the Ambrosia Lake Area in 1955, a new mining district has developed which promises to be the greatest uranium producing area in the United States. Exploration and development work is proceeding rapidly in mines operated by Kermac Nuclear Fuels Corporation, Phillips Petroleum Company, Rio De Oro Uranium Mines, Inc., Calumet & Hecla, Inc., Rare. Metals Corporation, Homestake-Sapin Partners, Homestake-New Mexico Partners, and Centennial Development Company. Individual mining operations vary in size from 200 tons to more than 1200 tons per day with production from wet and dry ore bodies ranging in depth from 300 to 1500 feet. Many problems have been encountered during the development period in the district mines. Within this paper the author will review some of these problems and mining practices being used. In order to understand better the developments to date, a brief description of the area and its geologic setting will be presented.

Jan 1, 1959

By M. M. Kirk

Forced-air cooling of cold-mold arc furnaces for melting zirconium and similar metals has been investigated and found to be practical from the stand-point of heat transfer. It is believed that this technique offers a significant reduction in explosion hazard from that inherent in water cooling, the current industrial practice. A copper crucible, with longitudinal, integral-type fins and with an outer jacket to confine the airstream, appears to be the best general design for air-cooled operation. Cutting the fins into short segments and bending the segments to produce a herringbone effect increased the airstream's turbulence and was found, on test, to increase the heat transfer up to 35 percent.

Jan 1, 1959

By F. A. Forward, A. H. Ross, J. Halpern

Application of the carbonate leaching process to carno-tite ores has often been limited by the difficulty of obtaining simultaneous high recoveries of uranium and vanadium. The chemical aspects of this problem are discussed and the effect of prior roasting procedures on this discovery is described. IN treating carnotite ores by carbonate leaching it is often necessary to subject the ore to a prior roast. Among the advantages that may result from roasting are: 1) improvement in settling and filtering characteristics of the ore; 2) destruction of carbonaceous impurities that would otherwise contaminate the leach solution and consume carbonate reagent; and 3) substantial increase in extraction of vanadium, which is usually low when the un-roasted ore is leached. Recovery of vanadium may be an important factor in processing carnotite ores, and the fact that vanadium is usually recovered in good yield by acid leaching has often been an economic advantage over results obtained with carbonate leaching. It has been found that response of an ore to carbonate leaching, following roasting, depends primarily on its composition and on the conditions of the prior roast treatment, particularly with regard to the roasting temperature, the atmosphere maintained above the charge during roasting and cooling, and the presence of certain reagents. These factors, especially the last, virtually determine the extractions of uranium and vanadium attainable by carbonate leaching, as well as the reagent consumption on leaching, whereas adjustment of the leaching conditions has only a limited influence. These variables were examined systematically to elucidate roasting and carbonate leaching of carnotite ores and to establish a treatment yielding high recoveries of both uranium and vanadium. Tests were conducted on samples of four different Colorado Plateau ores, described in Table I. Roasting Procedure: The roasting tests were conducted in an electrically heated furnace in which the temperature was controlled to ±15°C. The ore (usually a 500-g charge) was ground to —100 mesh, mixed with the desired reagent, and spread in a silica tray to a bed depth of about 1/2 in. During the roast the charge was rabbled at intervals of 15 min. To provide free access of air the furnace was usually ventilated; however, in a few experiments a controlled atmosphere such as carbon dioxide or hydrogen was maintained above the charge. Leaching Procedure: The pulp, generally comprising 500 g of ore and a 2000-cc solution containing 80 g per liter of Na2CO8 and 20 g per liter of NaHCO3, was agitated in an autoclave at 120°C, under 30 psi 02. Samples were withdrawn periodically, and the solution and ore residue were analyzed. Under the conditions employed, maximum attainable extractions were generally achieved in 4

Jan 1, 1959

By J. C. Underwood

"The wear performance of grinding balls under conditions of impact and abrasion is affected by their chemical composition and structure. The selection of appropriate analyses and heat treatments that will provide both abrasion and impact resistance takes into account the effects of certain elements on structure and harden-ability, as well as the over-all effect of composition and hardness penetration on the residual stress pattern developed through heat treatment. Direct quenching from forging temperatures substantially increases hardenability over that obtained in reheat-quench practices, and can be done without undue risk of damage to the ball provided that the harden-ability bears the correct relationship to ball diameter.Average volumetric hardness and percent hardened volume are convenient parameters for quantitatively expressing the response to heat treatment and indicating anticipated wear properties. A number of factors which can lead to reduced wear life as a result of material or processing problems are reviewed and illustrated."

Jan 1, 1959

By D. W. Frommer

As one phase of a general problem of recovering sulfide slimes, mineral-dressing research was conducted on flotation tailing from the St. Joseph Lead Co., Bonne Terre, Mo., mill to recover a significant portion of the residual, finely divided galena. Production of a high-grade concentrate was not part of the immediate objective. Only a reasonable ratio of concentration of lead sulfide slime was sought, since the problem of upgrading by mechanical or extractive processes would be considered in the later stages of this study. The results show that, from a feed material averaging 0.20 percent lead (about 70 percent finer than 400-mesh), a recovery of up to 45 percent could be effected by flotation in rougher concentrate analyzing up to 6.5 percent Pb. These results were obtained by using larger quantities of various xanthates and sodium sulfide than used customarily in mills. Sodium sulfide, which is ordinarily detrimental to flotation of galena, was beneficial in this case.

Jan 1, 1959

By Myron W. Mellor

Much has been published concerning the subject of coal preparation as related to electric power generation however it is always a most vital topic for both utilities and coal producers, It also constitutes a field of study that is never finished since new concepts and changing demands continually require altered perspectives. One graphic illustration that has been used to emphasize the rapidity with which times are changing is the fact that during World War I, a station that consumed 1000 tons per day was looked upon as a large central station, while today some single generators require 1500 tons during the same period, For further emphasis, at that time a 20,000 horsepower turbo-generator was a mighty large machine; today, a unit of this size is planned for driving the boiler water feed pump required for a single large main unit. During the past ten years alone, electric utilities have more than doubled their percentage of coal consumed as compared to the total market. They now account for approximately 40% of the United States consumption and one-third of all production including export, Conversely, approximately 70% of all U. S. steam electric generation is by coal and this percentage is expected to increase. It is further predicted that utility consumption will increase from the current 160,000,000 tons per year to between 400 and 500 million tons in 1975 which is approximately equal to todays total production

Jan 1, 1959

By C. E. Hennig

On January 1, 1959, the United States had 313 petroleum refineries with a total installed crude-oil throughput capacity of 9,819,846 barrels per day, according to the Bureau of Mines annual survey. Compared with a year ago, this represents a net decreased of five in the number of slants mild a net increase in capacity of 412,139 barrels per day. The continued increase in total capacity and decrease in number of plants raised the average capacity of a refinery to a new high of 31,373 barrels per day. During 1958 total capacity increased in every refining district except the Louisiana Gulf district, which showed a 2-percent decrease due mainly to the retirement of the American Oil Company's plant at Destrehan, La. The largest increase, 14 percent, occurred in the Texas Inland district followed by a 12-percent increase in the Arkansas-Louisiana Inland district. At the beginning of 1959 the industry was building facilities that would add 108,400 barrels per day to crude-oil capacity. It also had under construction a capacity of 226,100 barrels per day as replacement. On January 1, 1959, no new refineries were under construction.

Jan 1, 1959

B. P. Thomson (South Aust. Dept. of Mines): Dr. A. B. Edwards presents in the published discussion on the above paper, his interpretation of the dolerite dyke-lode relationship as a major objection to the syngenetic origin for Broken Hill ore bodies to which Mr. Condon subscribes.Dr. Edwards claims that the dyke-lode relationships indicate clearly that the Broken Hill orebody was formed after the folding and regional metamorphism of the Willyama Series. Field evidence compels m:e to join with H. F. King (1958), in finding this conclusion unacceptable-as follows:(1) Broken Hill type mineralization, as defined by King and Thomson (1953), is clearly confined by the regional sillimanite isograd and does not extend into the lower temperature almandine and biotite zones as does the Thackaringa type mineralization.(2) In the Corruga area the writer has mapped a dolerite dyke apparently cutting a conformable quartz gahnite lode of the Broken Hill type (see Edwards 1958, p. 12).(3) At the Champion mine a similar lode is cut by a fine grained granite dyke.An alternative history of the dolerite dykes to that given by Stillwell & Edwards (1956, p. 26) appears possible. It has been suggested by the writer in an unpublished thesis, (Thomson 1955, p. 30), that the pyroxenite and serpentine plugs and dolerite dykes are rheomorphic end-products of a complex regional metamorphic and metasomatic process involving the formation of amphibolite and pegmatite. The analogy in composition between the dolerite and normal amphibolite is close (see Edwards 1958, Fig. 1, p. 22).

Jan 1, 1959

Descriptions of the following awards and lists of recipients through 1957 may be found in 1957 AIME Directory Recipients since that time are as follows JAMES DOUGLAS GOLD MEDAL 1958-J Roy Gordon "For distinguished contributions to process metallurgy in the field of smelting and refining of nickel, and metallurgical improvements in nickel recovery " 1959-Clyde Williams "For outstanding contributions in nonferrous metallurgy partic¬ularly through stimulating research and interest in the basic metallurgy and the use of both the common and the less common metals " WILLIAM LAWRENCE SAUNDERS GOLD MEDAL 1958-Willlam Jesse Coulter "For his distinguished achievement in contributing in general to the success of Climax Molybdenum Company, and, in particular, for developing mining practices of the Climax Mine "

Jan 1, 1959

By W. L. Dare

This information circular is one of a series published by the Federal Bureau of Mines in which the methods and costs of producing uranium ore on the Colorado Plateau are discussed. This report describes the three largest company-operated uranium mines of Climax Uranium Co. - the G-1, the Mineral Joe, and the Frank No. 1. Climax Uranium Co., a subsidiary of American Metal Climax, Inc., was [corporated] May 11, 1950, just 2 years after establishment of the domestic uranium program by the Atomic Energy Commission. Twenty-five years earlier Arthur H. Bunker, now chairman of the board, American Metal Climax, Inc., organized and operated the U. S. Vanadium Co. at Rifle, Colo.3/ Soon after Climax Uranium Co. was organized, it entered into a contract with the Federal Government to build a uranium-vanadium processing mill in Grand Junction, Colo. Under the contract Climax leased from the Federal Government certain uranium-bearing lands that had been withdrawn from public entry in 1948. From Minerals, Engineering Co. on June 12, 1950, Climax acquired other uranium-vanadium properties on Calamity, Outlaw, and Monogram Mesas in Colorado and on Polar Mesa and in the Yellow Cat area of Utah. To house the milling equipment, Climax leased the old Grand Junction sugarmill building of the Holly Sugar Co. Milling facilities, based on a then new process developed for treating both uranium and vanadium, were completed, and the plant went into production in 1951.

Jan 1, 1959