Search Documents

By Frank Firmstone

IN Chemical Phenomena of Iron Smelting, Mr. Bell gives the weight of materials required to fill furnaces of various sizes at the Clarence Works ; as this differs very much from the weight required for furnaces at Glendon, where anthracite and magnetic and brown iron-ores are used, a comparison is interesting. Taking furnaces at Glendon of 4800 and 11,900 cubic feet capacity and comparing them with the Clarence furnaces of 6000 cubic feet and 11,500 cubic feet, we find that the 4800 cubic feet at Glendon and the 6000 cubic feet at Clarence required respectively-

Jan 1, 1873

By Robert Keeney

Before the outbreak of the war in 1914, the only electric-furnace smelting plant operating on a commercial basis west of the Mississippi River was an electric pig-iron plant in California; rare metal ores were not smelted, concentrates of molybdenum, tungsten, uranium, and vanadium ores being shipped east for reduction. Practically no- chrome ore was being mined, and only comparatively small amounts of manganese ore. Today there are two electric smelting plants in California, one in Washington, one in Iowa, and four in Colorado; two plants are under construction in California, and one in Montana. Ores of manganese, chromium, molybdenum and tungsten are now smelted in the West, and although uranium and vanadium concentrates are still shipped to the East, they will probably be treated in western plants in a short time. The four electric-furnace plants in Colorado are listed in Table 1. TABLE 1.-Electric Smelting Plants in Colorado Capacity, Company, Location Kilowatts Products . Tungsten Products Co Boulder 800 Ferrotungsten, ferromolybdentun. Boulder Tungsten Production Co. . Boulder 400 Ferrotungsten. Ferro Alloy Co Utah Junction 1200 Ferrochrome, ferrotung-sten. Iron Mountain Alloy Co Utah Junction 3000 Ferromanganese. Power for all of these plants is supplied by the Colorado Power Co.

Jan 8, 1918

By P. Marier, T. R. Ingraham

When anhydrous cupric sulfate is heated in a stream of nonreactive gas, cupric oxysulfate is formed. When this reaction is complete, the cupric oxysulfate then decomposes to cupric oxide, which is the normal end product of reaction. The kinetics of each of these reactions has been studied using pellets prepared from finely divided cupric sulfate and from finely divided cupric oxysulfate. In each case, the reactant-product interface within the pellet is well-defined, and by normalizing the decrease in inter facial area with the weight fraction of the pellet decomposed it has been shown that the interface migrates into the pellet at a uniform rate at constant temperature. The activation energy estirnated for the decomposition of cupric sulfate is 57 ± 7 kcal per mole and that for cupric oxysulfate is 67 ± 8 kcal per mole. The rate of interfacial reaction is flow-sensitive, increasing with increasing flow of a sweep gas in the range from 50 to 2000 cu cm per min. The rate of decomposition is retarded by sulphur trioxide in the sweep gas. The relationship between sulfur trioxide Partial pressure and rate is consistent with the Langmuir Adsorption Isotherm governing the retention of sulfur trioxide in the interfacial layer. MOST of the work reported on the thermal decomposition of cupric sulfate and of cupric oxysulfate is related to the thermodynamics of the individual decompositions.'-4 No information is available on the rates of the individual reactions, on their activation energies, or on the effects of gas flow or of partial pressure of sulfur trioxide on the reaction rates. Some dubious conclusions based on relative reaction rates have been drawn from studies on the oxidation of sulfides. For example, on the basis of the products observed in a quenched system, it has been suggested5" that, when copper sulfide is roasted, the cupric oxide which is formed arises from the decomposition of either cupric sulfate or cupric oxysulfate. This is very difficult to reconcile with the thermodynamics of the C-S-O System,3 which support the probability that both cuprous oxide and cupric oxide precede cupric oxysulfate and cupric sulfate in the sequence of products formed during the oxidation of cuprous sulfide. In this paper the individual sulfate decomposition reactions will be examined and suggestions will be advanced for the mechanism of reaction. This will be based on the effects on reaction rate of changes in interfacial area, flow rate, and back-pressure of sulfur trioxide. EXPERIMENTAL Materials. The copper source material used in all experiments was Fisher Certified Reagent Grade anhydrous cupric sulfate, for which the following analysis was supplied by the manufacturer: chloride, 0.002 pct; alkalies and earths, 0.2 pct; insoluble, 0.002 pct; iron, 0.020 pct. Cupric oxysulfate was prepared by roasting cupric sulfate for 48 hr, with frequent rabbling, in an open tray in a muffle furnace maintained at 725°C. At this temperature, cupric sulfate develops about 0.16 atm pressure of combined sulfur trioxide, sulfur dioxide, and oxygen. Cupric oxysulfate develops only about 0.05 atm pressure, and is stable until

Jan 1, 1965

By A. Kenneth Schellinger, O. Cutler Shepard

INTRODUCTION OVERGRINDING, or the breaking of ore particles into sizes smaller than required for liberation, is a first-magnitude problem in grinding for concentration processes. The conventional ball mill-classifier circuit used in commercial grinding produces mineral particles that are all ground to pass an upper size limit, while the proportion of very fine sizes, or slimes, is uncontrolled. Calculations based on measurements made in commercial plants which were grinding ore for flotation concentration indicate that about 90 pct of the energy used in grinding is consumed in useless overgrinding.1 In addition to accounting for the consumption of a large amount of energy, overgrinding is detrimental to the flotation process. Overground slime coats larger particles and inhibits selective action by the flotation reagents on particles which by themselves could be separated very well. A further difficulty is that extremely finely ground minerals do not respond satisfactorily to flotation-collecting reagents, and both selection and recovery decrease markedly with particles finer than 5 to 10 microns.2 Conventional classifier-ball mill circuits inherently tend to overgrind the valuable minerals more than the gangue minerals because most valuable minerals are of higher density and are softer and more friable than the gangue minerals. The remedy to this situation would seem to be a separating mechanism which would separate free valuable mineral particles regardless of size and density considerations and a mechanism which would operate in the grinding mill so that valuable mineral grains would be removed from the grinding machine as soon as they are freed. A consideration of these ideas led the authors to the conception of a simultaneous grinding and flotation mechanism. So far as the authors are aware, such a machine has never been tried, even on a laboratory scale. DEVELOPMENT OF APPARATUS AND EXPERIMENTAL METHOD Apparatus development went through several stages before a really workable machine was devised. Work was started with a large cast-iron mortar 7 ½ in. in diameter and 8 in. deep. A cast-iron disk was mounted on the end of a vertical shaft so that it fitted loosely into the bottom of the mortar. On top of the disk four radial cleats ¼ in. high were bolted to agitate the ball charge as the disk, or impeller, rotated. The vertical shaft was driven at 100 rpm by a mechanism improvised from an old coffeemill type of grinder. A hole was drilled into the bottom of the mortar through which compressed air was introduced for frothing. In operation, weighed charges of ore which had been crushed to pass an 8-mesh screen were placed in the bowl along with water and suitable reagents. The impeller was then started and the compressed air turned on so that the ore was ground while being exposed to air bubbles. Mineralized froth was

Jan 1, 1947

By A. Kenneth Schellinger, O. Cutler Shepard

Overgrinding, Or the breaking of ore particles into sizes smaller than required for liberation, is a first-magnitude problem in grinding for concentration processes. The conventional ball mill-classifier circuit used in commercial grinding produces mineral particles that are all ground to pass an upper size limit, while the proportion of very fine sizes, or slimes, is uncon rolled. Calculations based on measurements made in commercial plants which were grinding ore for flotation concentration indicate that about go pct of the energy used in grinding is consumed in useless overgrinding.1 In addition to accounting for the consumption of a large amount of energy, over-grinding is detrimental to the flotation process. Overground slime coats larger partitles and inhibits selective action by the flotation reagents on particles which by themselves could be separated very well. A further difficulty is that extremely finely ground minerals do not respond satisfactorily to flotation-collecting reagents, and both selection and recovery decrease markedly with particles finer than 5 to 10 microns.2 conventional classifier-ball mill circuits inherently tend to overgrind the valuable minerals more than the gangue minerals because most valuable minerals are of higher density and are softer and more friable than the gangue minerals. The rem- edy to this situation would seem to be a separating mechanism which would separate free valuable mineral particles regardless of size and density considerations and a mechanism which would operate in the grinding mill so that valuable mineral grains would be removed from the grinding machine as soon as they are freed. A consideration of these ideas led the authors to the conception of a simultaneous grinding and flotation mechanism. So far as the authors are aware, such a machine has never been tried, even on a laboratory scale. Development oF Apparatus and Experimental Method Apparatus development went through several stages before a really workable machine was devised. Work was started with a large cast-iron mortar 7½ in. in diameter and 8 in- deep. A cast-iron disk Was mounted on the end of a vertical shaft SO that it fitted loosely into the bottom of the mortar. On top of the disk four radial cleats ¼ in. high were bolted to agitate the ball charge as the disk, or impeller, rotated. The vertical shaft was driven at 100 rpm by a mechanism improvised from an old coffee-mill type of grinder. A hole was drilled into the bottom of the mortar through which compressed air was introduced for frothing. In operation, more charges of Ore which had been crushed to pass an 8-mesh screen were placed in the bowl along with water and suitable reagents. The impeller was then started and the compressed air turned On so that the ore was ground while being exposed to air bubbles. Mineralized froth was

Jan 1, 1949

SMELTING is a thing essential to the end for which ores are sought, for without it every ore is a useless stone. This art is especially needed by those who, drawn on by hope, have mined ores in large quantities with great expense and effort. For this reason it is worth while to use one's wits and, if ordinary ways should not suffice, to consider how to find new ways of smelting the ores in order to extract the metals and to purge them of their earthiness. For this reason I shall now tell you of blast and other furnaces, and I shall also tell you, in order that you may be warned, that whoever wishes to do this well must first look at the nature and quality of the ore. You will already have had enlightenment on this from the experiments on assaying and with this as guiding star it is necessary to make ingenious structures and to provide for-the other needs as necessary, for one ore requires iron and another lead. Since I have already spoken of these in their own places on their ores, it is not necessary at present that I repeat, but here I wish to speak only of copper ore as a companion of silver and gold, and of where art is most required and where difficulties chiefly appear. For these things a machine must be built that is convenient to a good water supply in order to continue the work more easily. Its wheels should be large and easily moved, constructed in such a way that the force of the water lifts the bellows that are placed at the tuyère to direct the blast inside the furnaces that are to smelt the ores. For this, attention must first be given to the site of the machine, the quantity of water, and its fall; then to the wood for building the machine and for making charcoal; then to the stones that are used for the blast furnaces; then to the provision of good bellows that are wide, long, and full in their sides and made of cloth, for the better these are, the more they quicken the power of the charcoal

Jan 1, 1942

By Harry L. McNeill

THE Selective Media Process was developed by the author in a laboratory provided by The Steårns-Roger Manufacturing Co. It is the outcome of an [ ] investigation into the possibilities of coarse beneficiation by sink and float without using the conventional heavy media. Commercial work to date has been limited to the treatment of minus 3/8-in. iron ore at the Hill Trumbull washing plant of the Cleveland Cliffs Iron Co., at Calumet, Minnesota. Two cut away prints of the machine are shown (Figs. I and 2). A rotary conical impeller is mounted within a stationary cone (Fig. 2). This impeller is adjustable vertically by a 12-ton screw jack. The speed of the impeller can be varied from 14 to 32 r.p.m. by the Reeves variable-speed motor pulley mounted on the 7 ½ -hp. motor drive. Attached to the bottom of the stationary cone is the automatic control valve for sink product, actuated by a ¼ -hp. gear motor. The sink product is dewatered in a conventional drag driven by a 7 ½ -hp. motor and discharged onto an inclined conveyor containing from 6 to 10 per cent moisture. Two plants are operated at the Hill Trumbull property. All the ore is first treated in a typical washing plant (Fig. 3). When treating "wash ore" a finished concentrate can be produced by the log washers and Akins classifiers, as the separation involves only fine silica (minus 48-mesh) and free iron. However, when "jig ore" is fed to the washing plant the coarse

Jan 1, 1946

By J. S. Kasper, R. M. Waterstrat, B. F. Decker

THE large difference in the X-ray scattering factors for molybdenum and manganese makes the o- phase in the Mn-Mo system an interesting one to study with respect to ordering of the atoms. Such a study has been carried out using data obtained from a powder sample, and the resulting evidence for ordering in this compound is presented here. It is not possible, of course, to obtain all the details of structure for a u phase from powder data only. Most difficult of all would be the determination of precise atomic parameters. There is reason to believe, however, that the atomic parameters do not vary greatly in the different s'S and that the precise values obtained from one s structure would then allow decisions as to the ordering of atoms to be made when there is a large difference in scattering factors. In particular, the powder intensities for Mn-Mo s are for the most part in good agreement with those observed for Co-Cr, for which single crystal studies have been made by the authors.' There are a few marked discrepancies in the intensity comparison of the two s's, and these cannot be removed by adjustment of the parameters. They are interpreted as resulting from a more pronounced effect of ordering of the atoms. Accordingly, the parameters of Co-Cr s' have been used for the calculations of the Mn-Mo intensities. For Co-Cr, the space group is D4h14-P4/mnm with atoms in the following positions: 1—2 in (b); 11—4 in (f), with x=0.1031; 111—8 in (i), with x= 0.3713 and y=0.0370; IV—8 in (i), with x=0.5662 and y=0.2396; and V—8 in (j), with x=0.3160Y and y — -0.250. The unit cell is tetragonal, with an==9.10A and cn=4.74A for the Mn-Mo u phase studied here.

Jan 1, 1955

By John Dodd

This paper reviews advances in the technology of abrasion resistant iron and steels, which could help combat abrasion and wear in mining operations. With the recent progress in high chromium alloy iron development, high temperature heat treatment of massive castings can be eliminated, aloy cost reduced, and cracking problems avoided. Data on erosion-corrosion resistance of these irons; trends in the development of improved cast steels; and factors influencing toughness and abrasion resistance of manganese steels are all considered. The 7% Mn. 1% Mo manganese steels are shown to combine toughness and abrasion resistance, and composite castings are a means of combating abrasion in applications involving severe impact. A brief appraisal is given of recently developed martensitic wrought steels with improved weldability.

Jan 1, 1982

The following record of the important responsibilities already shouldered by Dr. Ricketts will give some indication of the trust and confidence reposed in him by his colleagues. The Institute is to be congratulated that a man who is already so much engaged should be willing to assume the further responsibility of guiding the Institute's Ship of state during the ensuing year. Louis Davidson Ricketts, who is brother of Professor Palmer or Chamberlaine Ricketts, President of Rensselaer Polytechnic Institute, was born at Elkton, Md., Dec. 19. 1859, was graduated from Princeton University in 1881 with the degree, Bachelor of Science, chosen a Fellow in Chemistry and W. S. Ward Fellow in Economic Geology, and after two years' study given the degree Doctor of Science. Following the completion of Iris work at Princeton, Dr. Ricketts went to Colorado and started to work as a mine surveyor. For the 15 years following, his time was chiefly occupied in reconnaissance work, geological work and mine examination. From 1887 to 1890 Dr. Ricketts was Geologist for Wyoming, and at, the end of that period transferred his operations to the Southwest. where he has since been steadily engaged in large mining projects. He was identified with the acquisition of the property now owned by the Moctezuma Copper Co., a , subsidiary of Phelps, Dodge & Co., at Nacozari, Sonora, Mex. From 1899 to 1901 he was General Manager of the property and during his administration the concentrator and reduction works were completed and the mines put on a dividend-paying basis

Jan 3, 1916

By Philip D. Wilson

IT has been my privilege to read the article prepared by R. S. Dean entitled "Production of Alumina from Low-Grade Domestic Materials" which appears on another page of this issue. Dr. Dean should be congratulated on the preparation of such an erudite and scholarly dissertation on bauxite and on the work which the Bureau of Mines has been doing in connection with the development of processes to use low-grade domestic materials.

Jan 1, 1943

By R. B. Kelly, Paul Martin

Central Texas added 76 producing oil and gas wells during the year, abandoned 378 wells in the same period, and produced 10,359,905 bbl. of oil in the 12 months under consideration. The oil production represents a decline of only 3 per cent as compared to 1934, but it must be remembered that much new production was added during the year. The activity in new work centered in Frio, Bexar, Williamson and Cald-well counties, with development in the Pearsall, Von Ormy and Byersville fields taking first importance. New discoveries in 1935 were confined to Pearsall area of Frio County and an extension to the Darst Creek field in Guadalupe County. The Red Lake field, in eastern Freestone County, proved itself of importance from the standpoint of a gas reserve but no oil production has yet been obtained. In Bexar County, the Von Ormy field, in which the discovery well was drilled early in 1934, completed 22 oil producers during the year. (A map of Central Texas showing location of oil and gas fields was published in Volume 114 of the A.I.M.E. Transactions.) New Fields Pearsal1.—The Amerada Petroleum Corporation, in developing its 60,000-acre block in Frio County, has definitely proved the existence of commercial oil production in four separate horizons; namely, the Navarro, the Austin Chalk, the Buda and the Georgetown. The discovery well, a two million cubic foot gas well, was tompleted in 1934. A test of the Trinity sand at 10,050 ft. found salt water but later was plugged back and finished as an oil well in the Navarro sand. Most recent of their discoveries has been in the Austin Chalk at a depth of 5666 ft., where a 24-hr. gage through 1-in. choke showed 2640 bbl. of pipe line oil. The oil has a gravity of 28.0" A.P.I. and is brownish in color. Because of lack of pipe lines in the area, the wells are produced only for short periods of time, and it is predicted that development will be slow until the district is entered by pipe line purchasing companies. Von Ormy.—In March, 1934, Umbren et al. completed their Wentz

Jan 1, 1936

By Paul Martin, R. B. Kelly

Central Texas added 76 producing oil and gas wells during the year, abandoned 378 wells in the same period, and produced 10,359,905 bbl. of oil in the 12 months under consideration. The oil production represents a decline of only 3 per cent as compared to 1934, but it must be remembered that much new production was added during the year. The activity in new work centered in Frio, Bexar, Williamson and Cald-well counties, with development in the Pearsall, Von Ormy and Byersville fields taking first importance. New discoveries in 1935 were confined to Pearsall area of Frio County and an extension to the Darst Creek field in Guadalupe County. The Red Lake field, in eastern Freestone County, proved itself of importance from the standpoint of a gas reserve but no oil production has yet been obtained. In Bexar County, the Von Ormy field, in which the discovery well was drilled early in 1934, completed 22 oil producers during the year. (A map of Central Texas showing location of oil and gas fields was published in Volume 114 of the A.I.M.E. Transactions.) New Fields Pearsal1.—The Amerada Petroleum Corporation, in developing its 60,000-acre block in Frio County, has definitely proved the existence of commercial oil production in four separate horizons; namely, the Navarro, the Austin Chalk, the Buda and the Georgetown. The discovery well, a two million cubic foot gas well, was tompleted in 1934. A test of the Trinity sand at 10,050 ft. found salt water but later was plugged back and finished as an oil well in the Navarro sand. Most recent of their discoveries has been in the Austin Chalk at a depth of 5666 ft., where a 24-hr. gage through 1-in. choke showed 2640 bbl. of pipe line oil. The oil has a gravity of 28.0" A.P.I. and is brownish in color. Because of lack of pipe lines in the area, the wells are produced only for short periods of time, and it is predicted that development will be slow until the district is entered by pipe line purchasing companies. Von Ormy.—In March, 1934, Umbren et al. completed their Wentz

Jan 1, 1936

The following is an extract of the Engineers' licensing law recently passed by the Colorado legislature; it went into force July 10. On the board of examiners are representatives of the four national societies. R. J. Grant, of Denver, represents the American Institute of Mining and Metallurgical Engineers; H. I. Reid, of Colorado Springs, the. American Society of Civil Engineers; H. S. Sands, of Denver, the American Institute of Electrical Engineers; and Frank E. Shepard, of Denver, the American Society of Mechanical Engineering. Within sixty clays after the taking effect of this act the Governor of the state shall appoint a State Board of Engineer Examiners, to be composed of five members, who shall be legal residents of the state of Colorado and who shall have been engaged in the practice of engineering for at least ten years. Upon the expiration of the term of any members other than the state engineer the governor shall appoint their successors for a term of four years, from a list of five nominees elected by the licensed engineers acting in a general assembly called together for this purpose by the president of the board. Such assembly shall be held in the month of January next preceding the expiration of the terms of any members. The Board of Examiners shall adopt all necessary rules, regulations and by-laws to govern its proceedings, not inconsistent with this act or the laws of the state or of the United States.

Jan 8, 1919

By William Paxton Hewitt

In the Santa Eulalia mining district, Chihuahua, Mexico, the main mineral zone occurs in a gently warped dome with simple associated structures and contains orebodies distributed through a vertical range of over 900 m. The stratigraphy of 1945 m of geologic column is described and an abrupt shrinkage is documented in the volume of limestones immediately associated with large orebodies. Termed collapse, this shrinkage occurred during the course of mineralization. Contacts of limestone with igneous sills, and 366 m of fossiliferous limestone beds, particularly the main fossil bed, have been important localizers of ore-bodies. Up-dip gravitational controls may have been important. Fractures have exerted only local controls and over short distances. Thrust zones have displaced diabase sills and in turn have been intruded by upper members of a group of rhyolite porphyry sills. Mineralizers were related to the rhyolite porphyry, and ore has been introduced to the limestone where certain sills lie between the displaced segments of diabase and have been cut by north-south fissures. Speculations are raised that fields of unreleased strain may have influenced orebody locations; the district's zoning pattern may be a reflection of the filtering effects of large volumes of limestone; and that metal-rich brines mobilized by or incorporated within the invading porphyry might be the source of the mineralizers. PRODUCTION AND LOCATION The Santa Eulalia district has a production record approaching or exceeding 35 million tons of silver-lead-zinc ore from replacement bodies in limestone. In operation since the first years of the 17001s, production has been confined to two intensely mineralized areas separated by 2 km of barren limestone, the West Camp and the East Camp. Probably 50% has been mined since 1908, with over 90% from the West Camp. The West Camp, exploited through a vertical depth of 1945 m and now approaching exhaustion, is the subject of this paper. The district lies in the northern part of the Santa Eulalia Mountains in central Chihuahua in northern Mexico, 400 km south of El Paso, Texas, and 22 km southeast of Chihuahua City. Dominating the northern part of the range is the Cerro de Santa Eulalia, a broad rolling upland which contains the district's West and East Camps. The West Camp, on the west side of the range, centers around the village of Santo Domingo, which is 2 km northeast of the Real de Santa Eulalia (Fig. 1). REGIONAL GEOLOGY Thick-bedded middle Cretaceous limestones, probably Aurora, form the great bulk of the Cerro de Santa Eulalia. These beds, warped into a gentle dome, are severed on the west by a faultline scarp and truncated on the north by the Dolores Pass, a wind gap that

Jan 1, 1969

By L. J. Kashar

By means of a continuum-mechanics approach, the following equation for calculuting the pressure for axisymmetric cold forging has been derived: where P is the extrusion pressure; K and n are the strength coefficient and the strain-hardening exponent of the steel, respectively; a and b are strain factors, primarily dependent on the die design; and R is the extrusion ratio. Data from compression and backward-extrusion tests performed at a crosshead speed of 0.5 in. per min on a nonwork-hardening material pure lead) and on a work-hardening material (1018 steel) indicate that the predicted extrusion pressures obtained from the derived equation agree very closely with the actual extrusion pressures. Therefore, the equation can be used to predict backward-extrusion pressures from standard mechanical-test data. The decision to cold-forge a part is based on several considerations, most of them related to economics. However, the production feasibility is usually determined by the pressure needed to extrude the part and the availability of tooling that can repeatedly sustain this pressure for over several hundred thousand cycles. A major contribution to the cold forging of steel would result from the development of steels that could be forged at reduced pressures and from the development of techniques that permit the accurate prediction of the pressure necessary to cold-forge the part. The ability to predict extrusion pressures is necessary to properly design the tooling required for the cold-forging process. Attempts to theoretically predict the cold-forging pressure, especially for work-hardening materials, have been unsuccessful in previous investigations of the cold-forging process.1-3 Many empirical relations have, therefore, been proposed relating the extrusion pressure to the chemical composition,' the extrusion ratio,2 the tensile strength,273 and hard- ness, 2 and the yield strength3 of the material being extruded. However, these empirical relations are valid only for the specific conditions used in their development, and, in some cases, the empirical relations had a scatter band greater than * 10 pct. A study of the extrusion process was undertaken with the objective of developing predictor equations for extrusion pressure by using a continuum-mechanics approach to the problem of metal flow. The derivation of such an equation is summarized in this paper, and data are presented that confirm the validity of the derived equation. DERIVATION OF THE EXTRUSION EQUATION If the extrusion of a material through a die is considered in terms of a work balance, it has been shown that it is possible to derive an equation relating the work necessary to move the material through the die to the deformation work undergone by the material. The work done, W, in moving the material is given by where F is the extrusion force, I, is the distance the material was moved, A, is the original cross-sectional area of the material, P is the extrusion pressure acting on A,, Ap is the cross-sectional area of the extrusion punch, and Pp is the punch pressure acting on Ap. The deformation work, WD, is given by where V is the volume of metal deformed, ay is the flow stress of the metal, and E is the total strain undergone in the extrusion. If there are no frictional losses, the work done, W, is equal to the deformation work, WD; therefore, Since the volume of a metal does not change during deformation,

Jan 1, 1968

By Myron K. Rodgers

In rock- or ore-crushing tests all data, in order to be valuable for study and comparison, should be obtained and tabulated under conditions as uniform as possible. The results of many such tests have no value for comparison, because of incomplete data and the lack of uniform conditiops, screens and scale of sizing, etc. The purpose of this paper is to suggest a form of standard specifications which may be developed by the Milling Committee and approved by the A. I. M. E. for rock-crushing tests. It is not intended to discuss any theories of rock crushing. Reports of rock-crushing tests should include the following details: 1. Description of the machine employed (jaw or gyratory crushers, rolls, stamps,tube mills, Chilean mills, etc.), 2. Method and material (timber, concrete, etc.) of foundation. Much power is dissipated in the vibration of poor foundations. 3. Locality from which the rock or ore was obtaincd, and geological, mineralogical, and physical characters of the material. 4. The power consumption of the machine running with no load and with full load, the unit of power being 1 hp. per 24 hr, 5. The capacity of the machine in tons (of 2000 Ib.) per 24 hr. 6. The duty in tons per horsepower-day. 7. The screen analysis of feed and product by the proposed A. I. M. E. standard screen scale. On the foregoing statement, the following remarlrs are offered. Toughness of Rock Table P shows the relative crushing duty of the same machine on three different characters of rock, all other crushing conditions being the same. This table indicates that the specific resistance of the rock to crushing, may affect the crushing duty of a unit of power as much as 300 per cent. Perhaps this quality may be called toughness. It is not a function of hardness only. For comparison of tests, rocks should be divided into

Jan 1, 1916

By John V. Beall

Copper production in the. United States in 1972 amounted to 1,658,000 tons according to the USBM. This figure is up over 1971 but falls below 1970 production of 1,719,101 tons. This report is essentially about the status of copper mining operations in the U.S. and is an update and expansion of the report "Southwest Copper-A Position Survey" published in [A=], October 1965. At that time, the trend was toward using larger equipment to mine lower grade ore and toward the expansion of dump leaching practice. That trend continues today but, it is overlain by intensive activity to comply with existing environ¬mental legislation and uncertainty over proposed revisions of venerable laws governing mining. In the U.S. today there is, practically speaking, no excess smelting capacity so that expansion of copper production through the startup of new mines is inhibited. Owners of a large undeveloped orebody would have to decide before going into production whether to sell the concentrates offshore, which has many problems, whether to try one of several unproved chemical processes for producing refined metal from concentrates or embarking on the construction of a traditional pyrometallurgical plant in the face of considerable uncertainty over the pollution standards that eventually must be met. The situation is such that not only is the present rate of U.S. copper production threatened but the ability to meet projected increased demand in the years ahead may have been severely retarded.

Jan 4, 1973

By M. E. Wadsworth, D. R. Wadia

The rate of reaction of cuprite was measured in a series of sulphuric acid solutions, from which oxygen had been excluded, at various concentrations and temperatures. The overall reaction CuzO + H2S04 + Cu " + CuO + H20 + So4' may be explained quantitatively by two simultaneous rate reactions involving not only H+ but also the hydrolytic adsorption of H2SO4. The results indicate the importance of considering surface mass balance relationships associated with heterogeneous surface reactions. T EACHING has long been an important method for the recovery of metals from certain minerals. Many processes have assumed minor importance in modern practice but such operations as the recovery of uranium and present interest in high pressure-high temperature solution of sulphides' ' well illustrate the importance of leaching as a unit operation. Little quantitative information is available in a form sufficient to determine the mechanism of solution at the solid-aqueous solution interface for given systems. For this reason, it is important that fundamental studies of leaching processes be conducted so that parameters associated with such surface reactions may be understood and correlated. Cuprite was chosen for this study as a result of a recent investigation carried out at the University of Utah on ores of the Ray and Chino Mines Divs. of the Kennecott Copper Corp. These sulphide deposits contain sufficient oxidized minerals, such as cuprite, malachite, and azurite, so that recovery of metal values contained in the oxidized fraction is of primary interest. Of these oxides, cuprite (Cu,O) is the most interesting, since it dissolves in sulphuric acid by an oxidation reduction couple resulting in the formation of 50 pct metallic Cu and 50 pct cup-

Jan 1, 1956

By J. van Lookeren

In the case of a reservoir where the oil underlies a large gas cap and overlies bottom water, production can be inzproved considerably if wells are perforated below the water-oil contact rather than opposite the oil-bearing section. The theoretical arguments for this improvement, which in some cases may be tenfold, are supported by experimental evidence. INTRODUCTION Reservoirs frequently consist of one sand body containing an oil layer underlying a thick, gas-bearing section and overlying bottom water (Fig. 1). Wells in such reservoirs are customarily opened up opposite the oil-bearing interval or, rather, opposite the lower part of this interval (Fig. 2). More often than not, it is inefficient or prohibited to blow off large quantities of gas with the oil. This im-psses a severe limitation on the drawdown, which results in low oil-production rates. Because of the small difference in specific gravity between oil and water, the latter will easily cone upwards, so that the production of water together with the oil is not prevented by this completion method. In such a situation wells should be opened deeper, in the originally water-bearing zone. The gas can be shut off by not perforating over the upper part of the interval (Fig. 3) or by a tubing hung close to the bottom of the interval (Fig. 4). Initially much water will be produced, but when steady-state conditions have been established (as depicted in Figs. 3 and 4) larger drawdowns are permissible than in a conventionally completed well, and correspondingly higher oil-production rates will result. Water cuts are only slightly higher because of the small effect of gravity on the water-oil flow distribution. CALCULATIONS The ratio of improvement has been estimated by means of approximate calculations. The completion depicted in Fig. 4 is the most convenient basis for these calculations. By postulating that vertical flow gradients can be disregarded, the Appendix shows that the well-known Dupuit formula can be obtained except for some complication due to the presence of two fluids rather than one. The Appendix makes the reasonable assumption that, for suitable boundary conditions, the oil layer occupies a constant fraction of the total fluid height throughout the reservoir. The oil- and water-production rates can thus be related to the liquid levels in the borehole as follows:

Jan 1, 1966