Search Documents

Quarrying and crushing 500 tons of limestone plus burning some 240 tons of limestone per day are the two initial phases in the production of borax, soda ash, sodium sulfate and related chemicals at Stauffer Chemical Co.'s plant in Westend, Calif. These processing steps have been upgraded in recent years by the installation of new primary and secondary crushers, an 8 x 340-ft rotary kiln plus kiln feed, control and cooling components-all designed and manufactured by Traylor Engineering and Manufacturing Division of Fuller Co. As a result of this new equipment, a new product- quicklime-has been added to the West End product family and considerable reductions have been realized in fuel and manpower costs.

Jan 1, 1965

By Merrill Horine

IT has been stated and accepted for many years that the automotive industry was the instigator, the principal sponsor for and the largest user of alloy steel and nonferrous alloys. The only universally recognized standard specifications and heat-treatments for these materials are those adopted by the Society of Automotive Engineers. It is this same auto-motive industry that has been the chief inspiration for and consumer of modern production machine tools. The production curve of steel ingots is more sensitive to fluctuations in automotive production than any other influence or group of influences. In every other important steel-con-suming industry, automotive materials and automotive processes are the outstanding features of modern progress. In this connection I need only mention the prefabrication of buildings, following the automotive system of straight-line, interchangeable mass production; the motorization of ships and railroads, employing automotive types of prime movers; the production of pressed-steel stoves, plumbing and furniture by methods originated in the automobile-body industry and the extensive use of rubber for the cushioning of all manner of machinery as pioneered by the automotive and tire industries. Dr. Jeffries has brought out this point in his address (p. 21), assuring us that the transportation industry is the largest user of these materials. In the transportation industry, or as we might more accurately express it, the transportation group of industries, the. automotive industry pre-dominates as a user of light alloys. One out of every four tons of aluminum produced is consumed by the automotive industry. Similarly, the automotive industry ranks first in the consumption of the following metallurgical materials: steel, 24.04 per cent; malleable iron, .57; alloy steels, 72.2; nickel, 30; lead, 39 per cent.

Jan 1, 1936

By P. K. Lucke

One of the interesting features connected with the great continental uplift, which formed the table land of Mexico, is the great depth to which oxidation and secondary enrichment of orebodies occurred. This table land lies at altitudes ranging from 4000 to 7000 ft. (1219 to 2133 m.) above sea level. Several cases could be cited of oxidized zones in copper and lead mines which reached depths of upward of 1500 ft. (457 m.) below the surface, and it is universally admitted that the oxidized zone in a mine is limited by the permanent water level. Mexico, however, like many other countries in which deserts occur, is visited at rare intervals by tremendous floods, which sometimes cause variable water levels over long periods. The following cases bear out the idea, and lead to interesting conclusions of commercial value. My paper demonstrates that carbonates of ores may occur below water level and sulfides above, and I will endeavor to explain the causes of the phenomena in certain specific instances. Case I.—Fig. 1 in this case shows that sulfides of lead remained

Jan 1, 1920

By Herbert K. Kutter

This paper is concerned with the physical phenomena in the fracture process of presplitting and only indirectly with the establishment of the optimum presplitting parameters. Its nature is therefore qualitative, rather than quantitative. Before examining the problem of presplitting, it is first necessary to study the phenomena which occur when an explosive charge is detonated in a borehole. To do this it is desirable to consider the action of the explosion wave separately from that of the expanding gases.l In the theoretical analysis such a separation poses no problems. Experimentally this was accomplished by use of an underwater-spark discharge to generate the stress wave and by pressurized oil to simulate the pressure of the explosion products. The main role of the wave is to generate a densely radially fractured zone around the borehole. The subsequent gas pressure, exerted against the walls of a highly (radially) fractured cavity, generates a quasi-static stress field (henceforth referred to as static stress field). This stress field was found to be the same as that of a pressurized cylindrical "equivalent cavity" with a radius equal to that of the crack tips. Under these conditions the quasi-static stresses become appreciable and cause further extension of the radial cracks. It was further found that, under gas pressure, the longest of the radial cracks would extend first, and extension of two diametrically opposed radial cracks requires the least pressure. From these observations concerning the single shot the transition to a whole series of more or less simultaneous shots, as in presplitting, can readily be made. In the case of multiple shots, as in presplitting, exactly the same effects occur, but at numerous locations and sufficiently close in time that they interfere with

Jan 1, 1968

By Edward Nichols

These deposits, which are found in James County, Tennessee, differ both in their mode of occurrence and in their chemical constitution from any other ores belonging to the same geological horizon which are known to the writer. Taylor's Ridge, or White Oak Mountain, is a long monoclinal ridge, which starts from a point near the Tennessee River in Meigs County, and, following a southwwt .course, extends unbrokenly into Cherokee County, Alabama, where it finally disappears. It is made up of strata of the Upper Silurian rocks, which dip to the southeast. To the eastward of this ridge, which is generally several hundred feet high, are a series of low foothills or knobs, composed of Clinton shales carrying seams of fossiliferous hematites. In the neighborhoud of the East Tennessee, Virginia, and Georgia Railroad, where it crosses the ridges, considerable ore has been milred from these seams during the pst ten years. Most of the workings have been superficial, and the ores mined, with one exception,,carry a silicious and nod-calcareous gangue, and contain from fifty to sixty per ceut. of iron.

Jan 1, 1882

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

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

Jan 1, 1960

By Richard D. Harvey, Arthur M. Squires, Robert A. Graff, George Kan

Particles of half-calcined dolomite (CaC03 + MgO) that had undergone cyclic absorption of H2S and regeneration with C02 in laboratory tests reveal enlargement of the crystallite grain structure, reduction in the number of pores but enlargement in their size, and partial development of a relatively dense mosaic microstructure on outer surfaces of cyclically reacted particles. Scanning electron microscopy, X-ray microanalysis, microprobe analysis, and X-ray diffraction techniques were used to evaluate microstructural properties of particles after tests conducted at pressures of 1 and 21 atm and temperatures of 7000 to 9000 C. The tests conducted at 7500 C and 21 atm showed the most favorable absorption and regeneration capacities of the dolomite tested. The changes in structure and pores play a major role in reducing the sulfur reactivity of half-calcined dolomite particles. The mosaic microstructure forms more rapidly at 1 atm than at 21 atm pressure. Once it occurs it seals the surface of the natural pore channels that existed in the half-calcined dolomite and restricts further conversion of crystallites of CaCO3 within the particles. Although a relatively coarse, granular mosaic of crystallites is present on some particles cycled at 21 atm pressure after only three absorption-regeneration cycles, it does not completely cover the particles, and that is true even after 30 cycles. Individual crystallites of MgO were not resolved by the X-ray microanalysis, but we believe that during the tests the MgO occurs as crystallites no more than 0.1 um in diameter that are homogeneously distributed through the particles, and it remains essentially inert during the reactions. The MgO contributes to the maintenance of the original fine-grained and microporous structure of the particles, an effect that is most advantageous to absorption and regeneration.

Jan 1, 1976

By Henry S. Washington

During the last twenty years or so the chemical investigation of rocks has made great advances, and it is now generally recognized that a knowledge of the chemical composition is as essential as that of the texture or mineral composition—if not more so—for the proper classification of rocks and study of their origin and relationships. Rock-analyses have vastly increased in number and, what is of greater importance, in quality. New and improved methods permit of greater accuracy than was possible in the early days, and the list of chemical constituents frequently determined has risen from the seven or eight of the greater part of the nineteenth century, to twenty or more. Indeed, rock-analyses with determinations of so many constituents are now commonly made by the chemists of the United States and Australia, while in Germany, Great Britain, France, and Italy the rarer constituents are determined more frequently than formerly. As a consequence of this modern, accurate work, it has been discovered that some elements which were formerly supposed to be rare are of wide-spread occurrence and are often present in considerable amount. The fact is further being developed that the elements tend to show certain relations of occurrence or abundance in connection with each other. This is a fact which is applicable to the rarer elements, and which also finds a broad geological and petrological expression in the recognition of petrographic provinces. We are beginning to obtain some definite, though as yet rudimentary, knowledge of the distribution of the elements among igneous rocks. Some of the results along these lines obtained by study of the vast accumulation of analytical data now available are well known to petrologists, while others do not seem to be so gener-

Jan 1, 1909

By R. B. Haagensen, E. Martinez, V. Kudryk

The sample under investigation contained approximately 16% BaSO, and was 80% -325 mesh. Established methods for floating barite did not produce concentrates of satisfactory grade or barite recovery because of low barite content and the presence of 6% calcite in the feed. By using a new long-chain sulfosuccinamate collector in combination with relatively high concentrations of sodium silicate, a barite concentrate was produced that would be acceptable as an oil-drilling mud using a simple rougher-cleaner circuit. No desliming of the fine-ground feed was necessary. Barite recovery was over 80% and the concentrate produced had a specific gravity higher than 4.3. During the course of the investigation, a procedure was developed to obtain semiquantitative determinations of barite, calcite, quartz, and feldspar in test samples using an infrared spectrophotometer. Samples were also analyzed in a thermobalance for determination of the calcite content. The use of these instruments made it possible to obtain quick mineralogical assays and proved to be of invaluable assistance in guiding the flotation testing.

Jan 1, 1976

By Titus Ulke

About two years ago, in making an examination of the Etta mine for the Harney Peak Tin Co., I discovered, in a vertical secondary quartz-vein in the granite massive of Etta mountain, the mineral about to be described. The vein was from a few inches to 3 feet wide, and was exposed for a length of about 15 feet. It was

Jan 1, 1893

By Sergio G. Jarpa

A mining project is, at one and the same time, capital intensive and highly risky. Besides, because of its usual long projected life, the operating cost is more difficult to predict and offtentimes exceed, during the life of the project, the first investment manifold. The objective of this study was to evaluate the applicability of cost-capacity relationships as used in the chemical industry to mining operations and, when necessary, to develop new ones. With the aid of a computer library program available at the Computation Center of the Pennsylvania State University, the total investment in mining equipment was determined to vary exponentially with production capacity, and the scaling exponents for each class of equipment, i.e., drills, shovels, trucks and earth moving equipment, as well as for the total operation were calculated. Since the scaling exponent for the whole mining operation happened to be equal to 0.94, it was concluded that more significant economies of scale are achievable in processing plants than in mining operations. From the operating cost point of view, unit material cost was found to decrease more rapidly than unit labor for the same increases in production capacity. The analysis of cost centers revealed that drilling and blasting, which are materials-intensive operational stages, were the most favorable in achieving significant economies of scale. Hauling unit cost, on the other hand, decreased only slightly when production capacity increased.

Jan 1, 1977

IN order that you may be expert in every phase of this art of parting, I wish to caution you upon twelve points, all necessary, so that you may know beforehand what may happen to you and what provision you must make to obtain good results. Understand that the gain derived from this art lies in carrying out the work that you wish to do accurately and with profit, which means nothing other than working with certainty and seeing that there is no loss of gold or silver [69v] or substance of anything that is valuable in itself. For, since everything lost is silver or gold, it is valuable however little. it may be, and many little things obviously make one large one; for gain increases gain, and loss, loss. Therefore, you will have as your first task to seek to have the materials that you are to use for making the aqua fortis of as perfect a nature as possible. I tell you this because the saltpeter is often weaker and of worse quality than the alum. For this reason it is necessary to make an effort to have it not only well refined and free from earthiness but also of a nature as powerful as pig [dung] saltpeter, the color of which tends strongly toward yellow. In order to work better, you also refine this again before you put it to use, as I shall tell you in its place. Likewise, see if you can get alum of the red kind that comes from the Levant or from Cartagena, for it costs less and is more powerful. Furthermore; see that you have a good number of well-formed cucurbits of properly purified glass not too large and of, equal content and size. Above all, see that they contain, no indentations, bubbles, folds, or scratches, especially, in the, body or in the bottom, because they break easily and the nature and great force of the acid pierces them by eating away, and makes a little hole. For this reason, cucurbits. are always divided into four grades; one is taken for making aqua fortis, another for drying the waters when they are laden with silver, the third for recovering the acids from the separations, and the fourth are either rejected as useless or dangerous, or are saved for recovering the whites or for some other service. Whoever wishes to practice this art well should remember to keep a large supply of cucurbits, receivers, and alembics. The third is the precaution which one must take in luting them; first, to

Jan 1, 1942

By ABBOT A. HANKS

WHEN gold was discovered in California, and San Francisco grew almost over night from a handful of people to many thousands, one of the first difficulties experienced was the lack of money. Gold dust in considerable quantities was rushed into the city from the various mining camps but there was no money. Purchases were paid for by weighing out dust in hand scales. We can appreciate&apos; the difficulty of paying for a drink or buying a postage stamp under these conditions. All this gold was in the form of dust from placer workings and the first metallurgists were the assayers&apos; who melted and refined this gold, casting it into bars which were weighed, assayed, stamped with fineness; value, and the name of the assayer. Many .of these plants were of considerable size, handling shipments that were accumulated by banks and express companies throughout the "Diggings" and sent to San Francisco to be shipped by water to the eastern states. Several

Jan 1, 1931

By George Holderer

THE relation between man-hours of labor and production may be correlated for any industry, and already it has been widely used in piece-work studies. It is not in general use as yet for recording labor efficiency of an enterprise or an industry. An exception to this is the Cement Institute, which tabulates the man-hours used in each operation and FIG. 1.-LABOR PRODUCTIVITY IN COPPER MINING. thus gets the total man-hours per barrel of cement. The writer knows of one steel company that keeps a complete record of man-hours for every operation from mining the ore to finishing the product. No doubt many others find the information useful, and such a study could be of value to the mineral industries.

Jan 1, 1935

By H. William Ahrenholz

Many technical meetings were attended by mining people during the past year in which rock mechanics was either the main subject for discussion or was a prominent part of the program. Several universities continued to offer short courses in the applications of rock mechanics for practicing mining engineers. At the beginning of the year, the AIME Committee on Rock Mechanics achieved standing-committee status. It is to assume responsibility for coordinating all AIME activities in this area. Eleven professional societies are now participating in a newly formed Intersociety Committee for Rock Mechanics. AIME and its constituent societies has three representatives. Delegates from the Intersociety Committee will serve on the U.S. National Committee for Rock Mechanics which is being formed by the national Academy of Sciences.

Jan 2, 1967

By Andrew S. McCraeath

The treatment which a steel receives, and the uses to which it may be applied, are frequently determined by the percentage of carbon which it contains; and especially is this the case in the different steel works in this country. The part which this element plays in the composition of steel is such an important one that a process for its accurate determination becomes an absolute necessity.

Take a look at the maintenance force in some of Wyoming&apos;s surface coal mines and you&apos;ll notice a significant change-the workers are younger than ever and many have had little or no prior experience. The change is quite a departure from industry&apos;s previous "experienced only" hiring policy. It results, in part, from a successful training program offered by Casper College in Casper. Wyo..

Jan 12, 1978

By Wayne C. Hazen, James K. Kindig

As the complexity of hydrometallurgical systems increases, it offers new opportunity for applications of solvent extraction. However, the high capital cost of mixer-settlers for large flow rates is a drawback to wide application in base metal recovery. This paper presents information on the use of cyclone separators in place of settlers with attendant significant reduction in capital cost. Various flowsheet possibilities for this development are discussed.

Jan 1, 1972

By H. E. Cline, T. H. Alden

A study zvas made of rate-sensitive plastic deformation and superplasticity in alloys of lead and tin. These alloys (lead, PO-19 pct Sn, Sn-38 pct Pb, Sn-2 pct Pb, tin) were extruded, aged at room temperature, or melted and resolidified to produce a variety of ~nicrostrnctures. Flow stress us strain rate data were obtained frorn tension tests for strain rates between 10-6 and 1 min-1. The curve log o .us log £ was S-shaped jor fine-grained materials and approxinzately linear for coarse-grained nzaterials. At constant grain size, the behavior was relatively insensitive to conposition. High rate sensitivity (d log o/d log k) and superplasticity occurred at intermediate strain rates in fine-grained materials and are believed to be associated with a transition with strain rate in the mode of plastic flow. This transition was shifted to higher strain rates with increasing temperataire or decrensing grain size. The high rate rneclzanisrn is presunzed to be slip, while rnetallographic evidence sug-gests that the low rate lnechanism is pain boundary sliding. PEARSON&apos; discovered that extruded eutectic alloys of Pb-Sn and Bi-Sn could be elongated as much as 2000 pct in tension. The ability for stretching decreased with aging time or annealing to increase the grain size. At high strain rates, or if the material was in the cast condition, normal ductility was observed. Following deformation of the extruded Pb-Sn eutectic at low rates, Pearson observed an equiaxed granular structure on an initially flat surface, while rapid straining produced elongated grains. He attributed the large deformation in the extruded alloys to the persistence of extremely small grains to a temperature sufficiently high for inter granular flow. Avery and backofen2 measured the strain rate sensitivity of the flow stress, m = d In old In 6, in the Pb-Sn eutectic and established a correlation between m and the tensile elongation. In the extruded eutectic alloy the strain rate sensitivity was 0.1 to 0.2 at rapid rates and the elongation was small, while at low rates m increased to 0.4 to 0.6 and superplastic elongation was observed. They also noted a grain size effect. In the case of the cast Pb-Sn eutectic the strain rate sensitivity remained at 0.1 over the range of strain rates of their experiment (3 x 10"3 to 2 min-I). These authors suggested that diffusional (Nabarro-Herring) creep was the mechanism by which deformation occurred at low strain rates, while climb-controlled creep occurred at high rates. Two predictions of this model are that, at low strain rates, the strain rate sensitivity approaches 1, i.e., Newtonian viscosity, and that the strain rate at constant stress varies as D/L2, where D is the coefficient of self-diffusion and L the grain size. More recently, a mechanical and microstructural investigation of the dilute superplastic alloy, Sn-5 pct Bi, has been done.3 The results show that the high strain rate sensitivity is associated with a transition with strain rate of the mechanism of plastic flow. At low strain rates, grain boundary sliding and its associated accommodation processes were evident, while at high strain rates quasi-uniform slip was concluded to be the dominant deformation process. The following experiments were performed to extend our knowledge of the phenomena of superplasticity to a larger range of strain rates, compositions, temperatures, and microstructures in the Pb-Sn alloy system. The question of why a cast structure does not exhibit viscous behavior although it appears to have a fine microstructure2 was investigated.

Jan 1, 1968

By H. W. Mead, C. E. Birchenall

The rates of growth of graphite nodules in cast irons are calculated for a model of a growing graphite sphere surrounded by a shell of austenite through which carbon and iron are diffusing. The carbon is supplied by a cementite-austenite mixture at the outer edge of the shell. The calculated rates from carbon diffusion agree fairly well with the measured values, but the rates based on iron self-diffusion are much too low. Because the iron must be removed for the process to continue, o plastic deformation mechanism is suggested. THERE has been an unfortunate tendency in the literature of growth and dissolution reactions to identify the slope of a plot of the logarithm of the growth or dissolution rate vs reciprocal of temperature with the activation energies determined by diffusion measurements in chemically similar systems. If the solubility limits at the growing or dissolving phase interfaces change appreciably with temperature, such procedures may lead to serious errors in specifying the mechanisms controlling the rates of these processes. A reaction involving the simultaneous growth of graphite from and dissolution of cementite in austenite will be discussed here to show that substantial oversimplifications have been made in earlier studies of this process. From a dilatometric study of the overall y-range graphitization process, Bunin and Danil&apos;chenko&apos; found an apparent activation energy of 90 kcal per g-atom. They concluded that, since this value was much nearer the approximately 68 kcal per g-atom observed for self-diffusion in pure iron than it was to 32 kcal per g-atom for diffusion of carbon in iron, the rate-controlling process must be the diffusion of iron away from the growth interface to provide space for graphite to grow. Bunin and Salli&apos; bolstered this agreement with the observation that graphite forms preferentially at surfaces, cracks, and pores where free volume is present initially. Ziegler, Meinhart, and DeaconQ ad found an apparent activation energy for graphitization of 98 kcal per g-atom. This value, like that of Bunin and Danil&apos;chenko, applies to nucleation and growth occurring simultaneously. It is not generally assumed that nucleation is entirely diffusion-controlled. Treatments such as prior cold-working and prequenching, which strongly affect the rate of graphitization, would be expected to have little effect on diffusion processes occurring at the graphitization temperature. In any case 90 kcal per g-atom is not particularly close to the 54 kcal or lower to be expected for diffusion of iron which is carbon-saturated.&apos; The presence of silicon in iron is said to reduce the activation energy for diffusion,&apos; so its presence in cast irons would be expected to have a similar effect. The growth rates of nearly spherical graphite nodules have been studied by Brown and Hawkes." The initial rate of growth before impingement of adjacent carbon-depleted areas was found to be parabolic, and rate constants were measured at several temperatures. Their apparent activation energy for the growth process only was roughly 45 kcal per mol. Burke and Owen&apos; made growth-rate measurements on several alloys, recording appreciable induction periods, initial nucleation rates, and average radial growth rates based on an assumed linear rate of radial growth. They found that increased silicon content increases the ovel-all reaction rate and the initial rate of nucleation, and decreases the induction period. Assuming 1) spherical nodules. 2) constant volume rate of nucleation, 3) austenite in equilibrium with cementite at positions where the cementite is not depleted, and 4) a constant diffusion distance during the growth of a nodule, they calculated an apparent overall activation energy of 68 kcal per mol, which was related to an activation energy for nucleation of 79 kcal per mol and activation energy

Jan 1, 1957