Search Documents

J. C. WRIGHT.-The problem of organizing and maintaining a vocational class for those employees who are engaged in the mining industry depends on several most important factors. The first is the sympathetic cooperation of employer and employee; the second is to find the subject matter that must be presented to these men; and the third is to find the instructor who can present that subject matter. This is perhaps the most difficult, for we usually find a man who knows the material that is to be presented but is not a teacher or does not know how to organize his material. The man must know the subject matter from the standpoint of absolute contact with industry in order to be a successful teacher. I have come into contact with two kinds of schools organized in connection with mining occupations. In one type the instruction leans very largely toward elementary subjects, arithmetic, reading and writing and spelling; it is not of such a character as to help or improve the working man in his occupation in the sense that we are attempting when we speak of vocational education. In the other type of school, an engineer is usually employed as a teacher. He immediately begins to give the things with which he is most familiar and the instruction becomes such as only those who possess a high-school or college education, perhaps, are able to receive. In between these two schools is the school we are trying to, promote, a school that will meet the needs of those employed. MARGUERITE W. JORDAN,* Altoona, Pa. -Vocational education has become the business man's problem; for he is the keeper of that white elephant, labor turnover, and anything that will decrease the size of the monster is worthy of serious consideration. This vocational education can do; for it can supply many of those deficiencies in upbringing and. environment that make for the discontent and restlessness of our varied classes of unskilled labor: the Anglo-Saxon mountaineer; the Southern negroes who have crossed Mason & Dixon's line by the thousands, "searching satisfaction for our minds;" and the still greater number who have sought across the sea America, "the promised land.

Jan 4, 1919

By Charles F. Park

CORRECTLY speaking, iron ore is limited to any naturally occurring rock from which iron may be extracted at a profit, but in practice the term is frequently used to indicate borderline material or inaccessible material that may in the future become commercially profitable. This distinction is much more than quibbling about terminology. When a layman hears that there are about 45 billion tons of iron ore in the world he naturally thinks that sounds like quite a bit of rock, and what is the use of worrying about the depletion of so plentiful a material. He does not realize, nor does he stop to analyze. why iron ore in Europe and Japan may carry no more than 30 per cent iron while tremendous quantities of 50-60 per cent iron ore in Brazil are not exploited. To people in the iron industry the answer is obvious: the Brazilian material is inaccessible, and there is no suitable fuel near-by. In places closer to home, submarginal ore in considerable quantity contains undesired impurities, such as sulphur, phosphorus, or titanium.

Jan 1, 1947

Oceanographers are tooling up. Back of the build-up is Navy defense work and private business. Business is dipping toes in the ocean gingerly and not sure whether the motivation is based on logic or intuition. The problem is that new business opportunities in the oceans could explode rather than evolve. The question is when. At stake for earthlings are food supplies, mineral resources, oil and gas, weather forecasting, navigational systems, shore erosion control and sewage disposal, as primary targets. "Twenty years ago, offshore oil seemed a remote possibility for economic exploitation but today it is a reality. It became a reality largely because of the development of practical ocean seismic equipment and drilling platforms. Today the oil industry is looking at submerged-type drilling rigs. Mineral exploration in the sea is more expensive than on land now primarily because familiar land tools are being modified for sub- marine work." These were the ideas expressed by C. G. Welling of Lockheed Missiles & Space Co., at one of the many meetings that have taken place so far this year on development of marine resources. Welling's views indicate the rationale of companies that have already invested in the sea. Many companies, including those in mining, have observers who caution, "go slow." The continental shelfs and even the deep ocean floor represent to the mineral industries the age-old, enigmatic confrontation-is this the time to move? To no other industry, except Defense, are the results of correct timing so vital.

Jan 8, 1967

By Carle R. Hayward

The growing importance of metallography has caused a corresponding interest in the improvement of apparatus for preparing specimens of metals and alloys for microscopic examination. The purpose of this paper is to describe an electric heating-furnace, a grinding- and polishing-machine, and a device for mounting specimens, which are used in the metallographical work at the Massachusetts Institute of Technology. These three pieces of apparatus were designed and made in the laboratory of the Institute, and each possesses some original features which may be of interest. Electric Heating-Furnace. The accurate control of heat necessary for metallographic work is best obtained by the electric-resistance furnace. Uufortunately, however, even the platinum-wound furnaces cleteriorate with use and ultimately burn out, while the cheaper resistance-materials are often short-lived. Since the resistance-coil must be replaced from time to time, it is of advantage to be able to make this change with as little trouble as possible, and this is an important feature in the furnace shown in Fig. 1. A is a cylindrical galvanized-iron can, with two handles, B. A porcelain tube, C, passes through the central hole in the cover of the can and rests upon the asbestos disk, D; the bottom of the tube is held in place by the asbestos ring, 3. The space, F, around the tube is filled with powdered magnesia. G is an ordinary assay-crucible, with the cover inverted so as to present a smooth top for supporting a second porcelain tube, H. The latter is wound with " Excello " resistance-tape, 0.014

Jan 1, 1912

By Leon Y. Sadler, E. K. Landis

Froth flotation has been described by several authors" as being analogous to a first-order rate process. Although a few investigators"," have found orders other than one fit their data best, the rate is described most often by the first-order equation, [ ] where r is rate of disappearance of floatable mineral by flotation, C(t) is concentration of floatable mineral in the cell, t is time, and k is first-order flotation rate constant. One of the difficulties in using this rate equation to develop a mathematical description of an actual flotation process is the determination of a suitable value of the constant k. The value of k, which reflects the floatability of the floatable mineral, is dependent on the hydrodynamic conditions in the cell, type and concentration of flotation reagents used, pulp density, and pH, method of froth removal, aeration rate, particle characteristics, and many other factors. Therefore, it is reasonable to expect that each particle of floatable material has a distinct value of k and that a unique distribution of k values exists for given feed and cell conditions. This has been observed and discussed by several investigators, and mathematical descriptions of the batch cell and steady-state continuous cell with distributed flotation rate constant have been developed." The mathematical description in the form of a transfer function of the continuous or flow cell under unsteady-state conditions with a distributed flotation rate constant has not been presented in the literature. The purpose of this note is to make such a presentation. The basic features of the perfectly mixed continuous

Jan 1, 1974

By A. B. Fly

Borehole mining combines the principles of hydraulic mining, slurry mucking and rotary drilling. The borehole is drilled with conventional equipment and is cased down to the top of the mining zone. The borehole mining tool is comprised of the kelly-swivel assembly, multiple drill-pipe sections, and the jet-pump barrel assembly as shown in Fig. 1. The kelly swivel is fitted with a bail to support the mining tool. The kelly drive bushing engages the rotary table to allow the rotation of the mining tool while it is being operated. The jet-pump barrel assembly is comprised of the sidewall jet nozzles, the jet-pump assembly, the suction screen, and the tricone rock bit. Clean fluid is pumped at high pressure through the kelly hose to the high-pressure swivel on the mining tool. The high-pressure pipe conducts the fluid down to the sidewall jet nozzles, the pump jet nozzle, and the tricone rock bit. The sidewall jet streams cut the formation and wash the cuttings down to the rock bit. High-pressure fluid issues from the water courses to clean the bit and to agitate the cuttings. Rotation of the mining tool causes the rock bit to grind any oversize material enough to permit its passage through the suction screen. High- pressure fluid issues from the pump jet nozzle to provide the lift needed to pump the slurry to the surface. The slurry is discharged into the settling pits where the cuttings are deposited and the clean fluid is returned to the suction of the high-pressure pump.

Jan 3, 1969

By T. C. King

AT the new Graham-Central Mill of Eagle-Picher, near Galena, Ill., material is simultaneously dewatered and introduced into the ball-mill scoop boxes by the use of variable-speed, 24-in. spiral classifiers. This arrangement has proved satisfactory in that the moisture content of the wet feed is reduced, thus allowing maintenance of density within the mills, and a constant feed at any desired rate to the mills is provided. In this mill the primary feed is wet crushed to minus 1/2 in. and preconcentrated by jigs to produce a bulk lead-zinc-iron concentrate and a waste tailing. The jig concentrate is then dewatered by a conventional dewatering classifier and stored in bins ahead of the ball mills. Even though this material is well dewatered, the discharge at the bin bottom is sloppy because of the gradual drainage of the water from the surface of the particles. Conventional belt feeders with vertical cutoff gates are unsatisfactory because of the flushing characteristic of the wet sand.

Jan 9, 1950

By A. M. Gaudin

OLEIC acid, a standard flotation reagent, has generally been preferred to other fatty acids. Because oleic acid differs from saturated fatty acids by the presence of one carbon-to-carbon double bond and because the flotation operation is one in which extremely intimate exposure of the reagent to oxygen is obtained, it appeared possible that the value of oleic acid as a flotation collector was related to the oxidizability of its double bond. To test this hypothesis, the floated mineral, fluorite, was leached with a solvent capable of extracting the adsorbed reagent and the extract was analyzed.' Results show that oleic acid is not oxidized during flotation, although some oxidation can be obtained if the flotation operation is repeated many times and if oxygen in place of air is employed as the gas during flotation. Incidentally, it was found that linoleic acid which has two nonconjugated double bonds is not affected appreciably more than oleic acid. Linolenic acid which has three nonconjugated double bonds is measurably altered even during one flotation step, using air.

Jan 4, 1953

By George E. Beavers

It is well to understand at once that converter gas is always mixed with copper blast-furnace gas at Copperhill before entering the Glover tower, and, at times, roaster gas is also added along with the converter and blast-furnace gas. Fig. 1 is introduced to show the variations in the sulfur dioxide content of the gas and the ability of the acid-plant operator to control the variations, resulting in a very even grade at the Gay-Lussac tower entrance. The sulfur dioxide content of the gas entering the Gay-Lussac tower must be low and regular to assure low niter consumption. The blast-furnace gas alone is rather uniform as regards sulfur dioxide content and the variations, as shown in Fig. 1, are chiefly caused by converter changes—out for charging, slag pouring, copper pouring, and, of course, the "finish." The combined gas during the converter finish is, at times, almost free of oxygen and the sulfur dioxide content reaches 13.0 per cent. At such times air is added at the Glover tower.

Jan 1, 1934

Zinc is just now a very important metal. Its use in cartridges and shrapnel brass are in the public eye. But its uses after the war are no less important. Brass as an engineering material for electrical machin-ery, journal bearings, and plumbing fixtures takes fully 50 per cent. of the production, and its use in these lines would have been increased in the last few years but for the price. Its use for barbed wire is probably more in war time than in peace. In the composition of paints, it is becoming more and more necessary. One of the forms of pigment, litho- pone, is the base of nearly all interior wall paints; of all the sanitary enamels for bath-rooms and bath-tubs, and is now in great demand. Zinc oxide is also increasing in use for paint, and for manufacture of linoleum. When we realize that this district-Missouri, Oklahoma, Kansas and Arkansas-produces now over one-third of the zinc ore of the world, it is at once seen that a meeting where the geology, mining, concentration

Jan 6, 1917

By R. E. Sheppard, A. O. Martel

Zinc sinter plant fume is roasted to selectively sulfate the cadmium. Water leaching of the roasted fume recovers about 80% of the contained cadmium and produces solutions containing about 40 grams per liter cadmium and 10 grams per liter zinc. The solution is treated with sodium bichromate for lead removal. Cadmium sponge, precipitated with zinc dust, is briquetted, melted, and cast into commercial shapes. The residue from the water leach is acid leached with waste acid, solubilizing the zinc and residual cadmium. Impure cadmium sponge, precipitated with zinc dust, is separated from solution with cyclones and dewatered in a centrifuge. Air-oxidation- acid leaching of the impure sponge resolubilizes the cadmium. The resulting solution is neutralized, clarified, and treated for cadmium recovery with the water leach solution. The residue from the leached fume is water-washed and recovered in a centrifuge-thickener circuit. This residue contains lead sulfate and significant quantities of gold and silver. Manpower requirements are held to a minimum by automating operations within the Leach Plant.

Jan 1, 1973

By Edward C. Roper

Pegasus' Gold Ltd. operates two gold/silver heap leaching operations in the Little Rockies area of Montana. The Little Rockies has produced gold from underground operations on an intermittent basis from the 1880's to the early 1950's and from the open-pits on a continuous basis since 1979. Run-of-the-mine ore is drilled, blasted, sorted, loaded and hauled. The waste is dumped and compacted into 30 meter (100 foot) fills to be used for future leach pads. The leach pads have a central drain system and the impermeable membrane is constructed of bentonite and 30 mil PVC. The plants which have beenexpanded to 4900 Ipm (1300 gpm) capacity use the Merrill-Crowe process for gold and silver recovery. 4600 liters (1200 gpm) of the 9500 Ipm (2500 gpm) spray capacity is recycled through the old leach pads for upgrading before being processed. The gold/silver precipitate is smelted and the resultant dore' is shipped to a buyerhefiner. 1983 projected production is 2,177 kg (70,000 02s) of gold at a cost of less than $10/gm.

Jan 1, 1984

By J. H. Scaff, H. C. Theuerer

Germanium may be reversibly converted from n to p type by heat treatment. Data for the conversion and the associated changes in resistreatment.tivity are given and the results are interpreted in terms of changes in the donor-acceptor balance. MEANS for controlling the electrical properties of germanium in a predictable manner are of interest because of the increasing utilization of this element as the semiconducting material in electrical devices. Since both the mechanism and the magnitude of the electrical conductivity depend upon the kind and quantity of impurities present, the conductivity usually is adjusted by first carefully purifying the germanium, and then, by standard alloying procedures, adding the elements desired. The elements usually added are from the third or fifth periodic groups depending upon whether p- or n-type germanium is desired. However, in the development of germanium rectifiers during the war, it was found that it was possible also to modify reversibly the conductivity of germanium and even to produce conversion from n to p type by heat treatment.1,5 Since then a detailed study of this effect has been made. The data are presented in this paper and an explanation is offered for the effects observed. Preparation and Experimental Procedure The method used in preparing the germanium ingots for this investigation has been previously described.' The method consists essentially of (1) reduction of GeO2* and (2) preparation of a 50-g ingot from the reduced material. Graphite containers are used in both steps. In the first step the GeO2 is reduced in hydrogen at 650 °C to form a sponge germanium which, to assure complete reduction and to obtain massive materials, is fused subsequently in the reduction furnace by gradually raising the temperature to 1000°C. The button of germanium thus obtained corresponds to a yield of 99.8 pct. The final ingot is prepared by fusion of the germanium button in a helium atmosphere. A cylindrical crucible in a vertical silica tube furnace is employed and the crucible is heated by an external induction coil. The ingot is solidified from the bottom upward by raising the induction coil at a constant rate with power to the coil kept at a fixed value. In such ingots, segregation is normal and most of the impurities are concentrated in the last region of the ingot to freeze. It follows then that the major portion of the ingot is purer than it would have been if freezing had occurred in a random fashion. Moreover the orderly advance of the freezing surface during solidification establishes in the ingot a succession of surfaces of constant composition, if it is assumed that the liquid is homogeneous and that diffusion in the solid is negligible. Therefore, some information on the distribution of impurities in the ingot may be acquired by determining the shape of the solid-liquid interface at different stages of solidification. This is of importance because the concentration of impurities will be seen to affect the response of germanium to heat treatment. Such information is difficult to acquire by direct means, for the impurities responsible for the electrical properties of germanium prepared in this way are present

Jan 1, 1952

By C. W. Allen, B. D. Cullity, H. S. Choi

The torsional deformation of aluminum and magnesium crystals is investigated, with particular reference to the dependence of proportional limit on crystal orientation. The proportional limit is found to be governed by the average value of the resolved shear stress on the most highly stressed slip systems, but the proportional limit does not strictly obey a critical-resolved-shear-stress law. The behavior of a cylindrical single crystal stressed in tension is well known: plastic flow begins when the resolved shear stress on the most highly stressed slip system reaches a critical value. There is much less understanding of the effect of torsion on such a crystal and on the way in which the critical-resolved-shear-stress law should be applied to torsional deformation. In the present paper particular attention is paid to the dependence of plastic yielding on crystal orientation and lesser attention to the mechanism of flow after yielding has occurred. New work on aluminum and magnesium crystals is presented, and previous results obtained in this laboratory on magnesium1 are re-examined. STRESS DISTRIBUTION The problems involved in torsional deformation of single crystals are due entirely to the complexity of the stress distribution. In tension, if loading conditions are perfect, the shear stress on any particular slip plane is completely uniform over the entire area of that plane. In torsion, on the other hand, the stress on any selected plane in a particular direction varies not only from center to edge of the specimen but also around its perimeter. It is convenient to express the stress at any point in terms of t0, which is the shear stress acting at the surface of a cylindrical specimen on a plane normal to the axis and in a direction tangential to the cylinder. At point P of Fig. 1 this stress acts in the direction of axis 2 and is given by To = 2T/pr3 [1] where T is the applied torque and r the specimen radius. This stress can be resolved on any chosen slip system, and details are given in the Appendix. Let P be the point on the specimen surface where the stress is to be evaluated; P is defined by its angular distance A from an arbitrary reference line through 0 normal to the axis. his line is usually taken as the direction of incidence of the X-ray beam used to determine the crystal orientation.) Then the shear stress t, acting at P in direction Dona plane whose normal is N is given by Ts/TO = sin ? 0, cos ?d sin (?0, - ?) + cos ?, sin ?d sin (?d - ?) [2] where 0, and Od are the angles between N and D, respectively, and the axis, ?0 and ?d are the angles between the projections of N and D, respectively, on the transverse plane and the reference line through 0. By means of Eq. [2], the stress 7, acting in any given slip direction can be computed. In the previous work on magnesium1 only gross slip tangential to the specimen surface was considered, and this

Jan 1, 1963

By B. Otto Pixler

Mud-analysis logging provides identification of the fluid content of formations drilled by the rotary method and permits the accurate correlation of oil and gas shows with the depth. Mud-analysis logging eliminates much coring and has an especially important application in drilling programs when coring is particularly hazardous or the electric log is difficult to interpret correctly. An appreciation of the factors that influence the results of the mud analysis, such as rate of penetration, mud properties, coring, and characteristics of reservoir rock as related to the "flushing effect," permits a better understanding of the mud-analysis log. Recent studies of the relationship of the two gas readings obtained by the gas-detector instrument have proved significant. The difference between the total combustible gas reading and the higher molecular weight gas reading indicates the presence of methane. With few exceptions, zones not showing an increase of methane probably can be condemned. Mud-analysis logging furnishes valuable information, which generally cannot be obtained by other methods. Introduction Logging by mud analysis of wells drilled with rotary tools is a direct method of locating oil-and-gas-bearing formations. The use of this method of logging has increased each year until now more than 20 field units are being used in 13 oil-producing states and in some foreign countries. Several papers1-9 have been published in the petroleum trade journals describing in detail the equipment and the application of mud-analysis logging. This paper will discuss briefly the method and review its application and some of the late developments. Method As the drilling of a well progresses, the drilling bit dislodges and disintegrates a cylindrical section of the formation. If oil or gas is contained in the pore spaces of the cylinder, some of the contents of these porous spaces will be entrained in the drilling fluid. In wall logging by mud analysis, the mud is continuously examined for oil and gas on its return to the surface, and the results are correlated back to the actual depth of the hole at the time the mud was clearing the eyes of the bit. The test for gas is made by diverting a portion of the circulating mud from the flow line to a separator or gas trap, where the mud is thoroughly mixed with air and a portion of the gas entrained in the mud is removed. A stream of air is drawn coun-tercurrent to the flow of mud in the gas trap, thus materially assisting the separation of the gas from the mud. The air-gas mixture is then drawn into a "hot-wire" gas-detector instrument where the percentage of the combustible gas is determined. The presence of oil in the formation drilled is detected by a physical examination of the drilling mud under ultraviolet light. A sample of the mud is treated to reduce the surface tension and gel strength, after which it is placed in a viewing box. This box is so constructed that all external light is excluded and so that the sample may be subjected selectively to either ultra-

Jan 1, 1946

By B. Otto Pixler

Mud-analysis logging provides identification of the fluid content of formations drilled by the rotary method and permits the accurate correlation of oil and gas shows with the depth. Mud-analysis logging eliminates much coring and has an especially important application in drilling programs when coring is particularly hazardous or the electric log is difficult to interpret correctly. An appreciation of the factors that influence the results of the mud analysis, such as rate of penetration, mud properties, coring, and characteristics of reservoir rock as related to the "flushing effect," permits a better understanding of the mud-analysis log. Recent studies of the relationship of the two gas readings obtained by the gas-detector instrument have proved significant. The difference between the total combustible gas reading and the higher molecular weight gas reading indicates the presence of methane. With few exceptions, zones not showing an increase of methane probably can be condemned. Mud-analysis logging furnishes valuable information, which generally cannot be obtained by other methods. Introduction Logging by mud analysis of wells drilled with rotary tools is a direct method of locating oil-and-gas-bearing formations. The use of this method of logging has increased each year until now more than 20 field units are being used in 13 oil-producing states and in some foreign countries. Several papers1-9 have been published in the petroleum trade journals describing in detail the equipment and the application of mud-analysis logging. This paper will discuss briefly the method and review its application and some of the late developments. Method As the drilling of a well progresses, the drilling bit dislodges and disintegrates a cylindrical section of the formation. If oil or gas is contained in the pore spaces of the cylinder, some of the contents of these porous spaces will be entrained in the drilling fluid. In wall logging by mud analysis, the mud is continuously examined for oil and gas on its return to the surface, and the results are correlated back to the actual depth of the hole at the time the mud was clearing the eyes of the bit. The test for gas is made by diverting a portion of the circulating mud from the flow line to a separator or gas trap, where the mud is thoroughly mixed with air and a portion of the gas entrained in the mud is removed. A stream of air is drawn coun-tercurrent to the flow of mud in the gas trap, thus materially assisting the separation of the gas from the mud. The air-gas mixture is then drawn into a "hot-wire" gas-detector instrument where the percentage of the combustible gas is determined. The presence of oil in the formation drilled is detected by a physical examination of the drilling mud under ultraviolet light. A sample of the mud is treated to reduce the surface tension and gel strength, after which it is placed in a viewing box. This box is so constructed that all external light is excluded and so that the sample may be subjected selectively to either ultra-

Jan 1, 1946

By D. Perry, G. W. Binkley, G. K. Dumbauld, F. A. Brooks

A new cementing technique has been developed which is particularly applicable to permanent-type well completion operations. The technique makes use of the accelerating effect of calcium chloride on setting time and strength development of cement cake deposited in squeeze cementing. An unique feature is that the accelerator is applied after the unaccelera-ted cement slurry has been squeezed and the excess has been reversed from the well. Laboratory data on the accelerating effect of calcium chloride applied to the fi1ter cakes of three low-water-loss cementing compositions demorzstrate that the procedure results in relatively rapid development of strength and impermeability of the cement cake. Simulated squeeze-ceinenting tests made in the laboratory likewise corroborated the practicality of the procedure. The laboratory tests showed that a newly developed oil-emulsion cemerzting composition is more susceptible to acceleration of set than are modified cements containing high percentages of bentonite. The acceleration procedure has been used successfully in field operations. INTRODUCTION Nature of Problem In squeeze-cementing operations, a substantial amount of time is consumed in waiting on the cement to develop strength after it has been squeezed into the well. Frequently, an interval of 18 to 24 hours or longer is required for the development of strength sufficient to prevent failure of the cement during subsequent operations in the well. Reduction of this waiting-on-cement time offers appreciable savings both in time and in money. A particular type of squeeze-cementing operation to which an increasing amount of attention has been given is encountered in permanent-type well completion operations wherein perforations are to be squeezed off1. In this procedure, it is customary to pump the cement slurry down the tubing and out into the perforated section through a retractable extension pipe. Squeeze pressure is then applied, which forces the cement slurry into the perforations and causes the build up of a compact filter cake of cement within the perforations. The excess slurry remaining in the hole is then removed by reverse circulation. The extension pipe is then retracted, and, if a new interval is to be perforated, a perforating gun is run through the tubing. The newly perforated interval may then be tested by swabbing. In such operations, it has been customary to allow approximately 20 hours or so for hardening of the cement squeezed into the perforations. This time interval is usually measured from the time that the cement is reversed out of the hole to the time that subsequent swabbing is started. If the cement has not developed strength at the commencement of swabbing, the pressure differential caused by swabbing results in failure of the squeeze job. At the time that the work described in this report was initiated, particular consideration was given to the reduction of waiting-on-cement time in squeeze cementing by the permanent-type completion technique. Consequently, much of the experimental work was directed to this specific objective, though the process which was developed for acceleration of strength development has possible application in other than permanent-type completion operations. Method of Attack Although quick-setting cements

Jan 1, 1957

The plan recently started for the organization of a Division of Re-search and Statistics in the American Petroleum Institute will probably shortly be consummated. It is proposed to expend $500,000 annually for this research work. The organization's work, as now outlined, pro-vides for a Technical Director, who is to be in general charge of all the work. He is to be assisted by Consulting Technical Experts, who are to be distinguished specialists in the industry and are to serve without pay. In addition, there is to be an advisory committee made up of one representative from the Bureau of Standards, Bureau of Mines, Geo-logical Survey, American Institute of Mining and Metallurgical Engi-neers, Society of Automotive Engineers, National Automobile Chamber, of Commerce, American Society for Testing Materials, American Chem-ical Society, and the National Research Council. This committee is to meet regularly to discuss the problems of the petroleum industry. An engineer and chief economist are to assist the Director.- The econ-omist is to be in charge of statistics, economic phases of the industry, and publicity. It is the intention to centralize in the Institute all infor-mation that may be required by the States or Federal Government, which would be of value to members of the Institute. This includes prices of crude oil, refined products, and natural gas. The engineer of the division is to coordinate the research work to be undertaken by, the subdivisions of production, chemical engineering, utilization, and special research. Systematic study is to be made of the

Jan 12, 1919

By Lars Thomassen, Ernest Kirkendall, Clair Upthegrove

THE amount of research done in the last few years on the subject of diffusion in solid metals is significant of the importance of this problem. To review the literature dealing with diffusion is unnecessary here. Desch1 in 1912 reviewed the work that had been done on diffusion in solids and gave a bibliography of the literature published before that time. Mehl's paper in 19362 is an excellent review of diffusion in metals and contains a large bibliography. Of importance also for its review and bibliography is an article by A. I. Krynitsky.3 While considerable material has appeared in the literature on diffusion in brass, the amount of information is not great compared to that pertaining to some of the other alloys. Most of the information published is of a qualitative nature; that which is quantitative varies considerably. Thus the quantitative determination of the rates of diffusion of copper and zinc in alpha brass by a new method appeared worth while. In the present investigation the rate of diffusion of zinc in approximately the same composition alpha brass has been determined at three temperatures. PROCEDURE The method used consisted of plating copper on a beta brass, heating it to allow diffusion to take place, and measuring the concentration of copper by determining the lattice constant of the alloy. This method is unique in that it uses a beta brass of such a composition that at the temperature at which diffusion takes place the beta brass is saturated with copper. Thus, while the beta brass supplies the zinc, no diffusion takes

Jan 1, 1938

A filled stope is one in which the support for walls and men and, at times, for the back of ore, is furnished by waste rock or sand tailings. The filling may be rock sorted out in the stope or from the walls, develop-ent, or the surface. The orebody is mined in sections, each practically an open or timbered stope, filled wholly or in part before adjacent ground is attacked. As a rule, the filled-stope method is limited to overhand flat-back, stepped-face, or rill stopes. The examples given are Copper Range, Iron Cap, Verde district, Zaruma district, Lucky Tiger, and Silver King Coalition.

Jan 1, 1925