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By Richard Klimpel

This paper describes the effects of slurry viscosity on the selection-for-breakage and breakage distribution parameters in the wet grinding of ores. A series of experimental tests were run on laboratory scale ball mills. Slurry viscosities were modified by varying the solids/water ratio with and without the presence of selected chemicals. Very consistent and predictable correlations are shown to exist. The grinding parameters were calculated using a computerized back-calculation technique developed by Klimpel and Austin. Industrial scale circuit calculations and preliminary plant trial data suggest that considerable increases in throughput and/or fineness of grind can be achieved through the judicious use of chemical additives.

Jan 1, 1977

By Burdett Loomis

The advantages of gaseous fuel have been too fully set forth during the past few years to need recapitulation. Papers, arguments, and editorials have been issued, in a more or less general way, that would make volumes. Systems have found zealous advocates, and many promises of results that have sounded strangely in the ears of old-fashioned gas-makers, have been born of theory, and have died in the earliest throes of trial; while in some few instances success has demonstrated the value of practical effort. With few exceptions, however, everything attempted or accomplished has tended towards the one end-—the realization of more perfect results than we can

Jan 1, 1891

By L. C. Graton, Joseph Murdoch

I. Introduction......................... 26 1. The Relations of Scale in Geologic Work........ 26 2. General Characteristics of Copper Sulphide Ores..... 29 3. Scope of Present Study................. 31 11. Description of the Important Minerals............ 36 1. Pyrite....................... 36 2. Pyrrhotite....................... 41 3. Chalcopyrite...................... 41 4. Bornite........................ 40 5. Covellite....................... 50 6. Chalcocite....................... 52 7. Enargite...................... 59 8. Tetrahedrite and Tennantite.............. 61 III. Conclusions.......................... 62 I. Introduction. The Relations of Scale in Geologic Work. Many features of human accomplishment rest upon the possibility of representing natural objects on a scale of different magnitude from the actual one. Most drawings, for example, are of very different scale from that of the object depicted, and indeed are useful mainly 011 this account. More important than the question of mere convenience, however, is that of meeting the physical limitations of vision.' Thus, a mural

Jan 1, 1914

By W. B. Morrison

Anderson, King, and Spreadborough present detailed evidence to show what ~aldwin~' has already pointed out, that, over a relatively small grain-size range (Ad"1/2 ^ 10 mm-'I2, d is average grain diameter), yield point data can fit a number of relationships. Part of the difficulty in obtaining data which reflect only the effect of change in grain size on yielding arises from the fact that in varying the grain size, even though great care is taken, other structural changes are almost certain to occur. In iron alloys, these changes may consist of variations in subgrain size, grain boundary ledge density, and degree of carbon and nitrogen segregation at grain boundaries, all of which are difficult to detect and which may affect yielding, primarily through their effect on dislocation generation. Because of the inherent inaccuracy associated with yield point measurements there is little point in using relatively complex equations to fit data, as was done by Anderson et mnl., rather than the simpler, widely used Hall-Petch equation. In compiling their table of data, it is surprising that they did not include results from certain low-carbon steels,31 in which, as illustrated in Fig. 2, the grain-size range is very much larger than in their Armco Iron. The very fine grains in these steels were obtained by a thermomechanical process. Examination by electron microscopy showed that the grains were separated by high-angle boundarie and contained only an occasional subboundary. The data from these steels obeyed the Hall-Petch equation, and it was shown quite conclusively that they did not fit a d-l or (1-lJ3 relationship. Obviously, a much wider range in grain size than used by Anderson et al. is desirable if we are to determine the true relation between lower yield stress and grain size.

Jan 1, 1969

By G. G. Oberfell

THOUGH the largest volume use of natural gas has been, is. and in all probability will continue to be as a fuel for domestic and industrial heating, it has various market outlets, both as a fuel and as a raw material for the chemical industry. Natural gas is a preferred type of fuel where ease of control, fuel uniformity, and freedom from ash are of primary importance. Other industrially important uses are as a source of carbon black and as a fuel in various low-cost heating operations. Many other uses are of varying importance and new potential uses are continually being uncovered, some being of economic importance to the gas indus¬try as a whole, but most of them involve such small volumes of gas that they are only of passing interest. Since various products extracted from natural gas and recovered as by-products from petroleum refining, such as liquefied petroleum gas and fuel oil, are being utilized in many industrial and domestic heating applications, some consideration will have to be given such materials in order to present a reasonably complete story of the importance of natural gas. Some of these materials may prove to be transient competitors and will not be available when more profitable uses are found for them. Meanwhile, however, the potential volumes of such materials available, the current volumes being marketed, and the nature of the utilization are considered as constituting an essential part of the over-all fuel picture.

Jan 1, 1946

By K. Osseo-Asare

The thermodynamics of solid-aqueous solution equilibria up to 200°C In the systems Me-NH3 H2 0 (Me=Cu, Ni, Co) are summarized with predominance area diagrams generated with the DIAGRAM computer program. The implications of the diagrams to ammonia hydrometallurgy are discussed.

Jan 1, 1981

By W. Rostoker, S. A. Spachner

FOLLOWING the discovery of the w transition phase in certain titanium-chromium alloys by Frost, Parris, Doig, and Schwartz, much interest has centered on the alloys in which this phase is found and its mode of precipitation. The w phase has been found in alloys of Ti-Cr, Ti-Fe, Ti-Mn, Ti-MO,2 and Ti-v.3 The temperature-time-transformation characteristics have, as yet, not been determined for most of these. In this study, such transformation characteristics have been investigated for two heat-treatable titanium alloys known to exhibit transition phase phenomena. The alloys chosen, Ti-8Cr and Ti-13M0, are representative of two classes of binary equilibrium systems. In the

Jan 1, 1959

By Frank Harwood Riddle

Products made from the ores of the sillimanite group, and synthetic substitutes for them, have unique properties, and service tests prove that they are playing, and will continue to play, a major part in improvements in metallurgical processes. Also, they are examples of how comparatively useless, rare, or "museum" minerals have been made available in commercial quantities. Until research developed uses for them, the minerals had been observed only in small, scattered masses, or crystals. Improvements in ceramic processes and compositions have come about very gradually. In the last 10 or 15 years, several outstanding developments have been made. Of greatest interest to the mining and metallurgical engineers are those affecting the composition, necessitating the mining of new minerals, and improvements in ceramic products used in metallurgical processes. Sillimanite and Mullite Sillimanite (Al2O3.SiO2), then known as Fibrolite, according to Dana,' was first reported in 1792. In 1796, cyanite (Al2O3.SiO2) was first described.2 In 1873, Behrens published results of his microscopic study8 of porcelain. He showed that it contained what appeared to be crystals, which dissolved less readily than quartz and glass in hydrofluoric acid. Hussak4 described the presence of needlelike crystals as occurring in some instances in small amounts in certain porcelains. In 1908, Plenske and Zoellner both studied porcelain structure.5 Plenske observed that "sillimanite" might be present in masses of exceedingly minute grains which apparently were amorphous. Zoellner advanced the theory that the needlelike crystals were formed by a molecular change in the clay,

Jan 1, 1932

By Alan M. Bateman

POSSIBLE postwar trends of the more important world minerals will be determined in part by their present world position and by the acts and forces that have operated during the war period, so it is desirable first to review briefly what has been happening in the foreign field of metals and minerals. When we first entered this war we of the mineral profession were all acutely conscious of our lack of strategic minerals and other materials, which had to be imported in great quantities-minerals such as manganese, chrome, tin, mercury, nickel, and antimony. But we realized also that we had to acquire vast quantities of those minerals of which we had thought we were bountifully supplied. Our assumed domestic abundances turned out to be woefully deficient, and demands also arose for new minerals never before produced in large quantities. Some threescore minerals entered the strategic list of our imports. Ores from new sources had to be sought, developed, and transported. Tonnages in the millions of such bulk materials as zinc, lead, copper, chrome, and manganese flowed to feed our war efforts. Sparsely distributed minerals such as tin, mercury, antimony, tungsten, cobalt, mica, and corundum had to be lured from their rock lairs in greatly increased quantities to feed the hungry maw of war industry, and the rare minerals such as tantalite, columbite, beryl, and quartz crystals had to be developed and procured in quantities never before dreamed of. New uses such as radio and radar created demands for many minerals formerly thought of only as adornments of museum collections and not as pressing industrial minerals. Such minerals were never before mined in quantity.

Jan 1, 1945

By R. L. Fullman, J. W. Cahn

A method is derived for obtaining the distribution of sphere diameters and plate thicknesses (or pearlite spacings) from size distribution functions obtained along randomly oriented lines. The method described offers several advantages over existing methods. IT is often of interest to measure not only the average particle size but also the distribution in sizes of particles dispersed in an opaque material, such as an alloy. Particles of a single size will exhibit a range of apparent sizes on the plane of polish. If the sample contains a distribution of particle sizes, the distribution of observed sizes on the plane of polish is related to the distribution of actual particle sizes by an integral equation, For example, a distribution of sphere sizes, N(r),

Jan 1, 1957

By J. C. Osmond

One of the least known geologic regions in the U.S. is the area now called the Basin and Range Province. It is paradoxical that so little geologic information has been compiled for a province that has yielded billions of dollars worth of metals and is currently producing a small amount of oil. Regional stratigraphic studies of parts of this large territory have been published only recently, and regional structural interpretations of even parts of the province are rare in the literature. This, of course, does great injustice to the earliest workers: Gilbert,1,2 Russell,9 Le Conte,4 Spurr,5 Louderback,8 and others, who recognized the area as distinctively different from the rest of North America. Their simplified picture of the structure of the ranges and the province as a whole is the groundwork for present understanding and has never been superseded. Since their early works, however, geologic data from the province has consisted largely of detailed reports of widely scattered mining districts. Each district has been described as though it were an island in an unknown sea. More recent syntheses of the geologic history have been prepared by Lindgren,7 Ransome,8 Nolan,9 Bill-ingsley and Locke,30 Longwell,11 and Eardley.12 The tentative nature of the present interpretation, which treats the structural evolution of the Utah and Nevada area, must be considered in light of the scarcity of geologic information from the province as a whole. The methods of interpreting tectonic history from stratigraphy are based largely on the concepts of Marshal Kay.23 Discussions with Hoover Mackin also have aided in organizing the Tertiary history. TECTONIC AND STRATIGRAPHIC SETTING Two approaches to the subject of the tectonic history are possible; they correspond to looking through opposite ends of a pair of binoculars. One involves an expansion and extension of detailed work and the other an interpretation based on regional geological relationships. It is believed that the second approach, used here, is not in disagreement with detailed observations. The area of the Basin and Range Province is shown in Fig. 1. Within this area middle Tertiary to Recent high-angle faulting has controlled development of mountain ranges and valleys. Only the part of the area north of Las Vegas, Nev., and south of the Snake River in Idaho will be considered in this article. Within this part of the province most of the ranges trend north-south. Approximately two thirds of the area is covered by late Tertiary to Recent valley fill and lake deposits.

Jan 1, 1961

By David K. Hylbert

This study investigated roof falls in room-and-pillar drift coal mines in eastern Kentucky and utilized geologic methods for Predicting roof conditions in advance of mining. In the Highsplint mine, the roof was classified in four categories or conditions: Condition A and B (Laminated Shale); Condition C (Rolling Sandstone with Shale in Pockets); and Condition D (Zone of Major Sandstone Roll(s)). Structure contour and isopach maps of the Darby coal bed and associated immediate roof rocks were used to project axial trends of the sandstone roof. Trend mapping in the mine and on outcrop provided more detailed control for roof projections.

Jan 1, 1979

By A. F. Crowley, D. W. G. White

AS part of a continuing program of liquid metals research, the densities of liquid lead, tin, zinc, cadmium, and indium have been measured by a pycnometric method. The pycnometers are made of high-density graphite to the design illustrated in Fig. l(a). In pursuing this research program, emphasis has been placed on detailed experimental care. As a result, claims are made for densities accurate to within ± 0.05 pct over temperature ranges varying from about 100° to 200°C above the melting point. A paper reporting the densities of tin, lead, and Pn-Sn alloys has recently been published,' while papers dealing with

Jan 1, 1969

By H. D. Newell

THERE has been much research and commercial development in recent years in the use of chromium and nickel in steels of various types, including those intended for high-temperature service. By "high-tem-perature steels" are meant those specifically designed for service at ele-vated temperatures in steam plants, oil refineries and other industries where high-temperature operations are conducted. This paper is devoted to some preliminary data on the effect of silicon on certain of the most popular chromium-molybdenum steels now being used in quantity by the refining industry and includes a short statement on the influence of copper in steels intended for high-temperature service.

Jan 1, 1937

By H. Yoshida, B. G. Liebmann, R. E. Green

In recent years considerable work has been undertaken in order to gain an understanding of the mechanisms responsible for the generation of recrystal- lization textures in face-centered-cubic metals. Two theories have been proposed, that of oriented growth1 and that of oriented nucleation,' and several attempts have been made to check these theories directly by recrystallizing deformed single crystals.3-5 Two groups, Graham-Cahn and Liebmann-Liicke-Masing, studied the orientation of recrystallized grains and their rate of growth, both using strained aluminum single crystals of commercial purity (Graham et al., 99.6 pct, Liebmann et al., 99.8 pct). Surprisingly, the results obtained by the two groups were completely

Jan 1, 1960

By C. O. Tarr, G. V. Smith, R. F. Miller

METALLURGISTS have long recognized that the Fe3C type of carbide is not a stable phase in steel and that, given sufficient time, it will decompose with formation of graphite, at least at temperatures below about 2050°F.1 This slow graphitization has never been of much concern to users of hypoeutectoid steels, for in such steels it occurs only during prolonged exposure at elevated temperature. In 1935, Kinzel and Moore2 reported complete graphitization of the carbide of a 0.1 5 per cent carbon steel that had been in senrice for about 26,000 hr. at a temperature of about 1100° to 1200°F. In discussing this paper, both Mathews and Sauveur reported graphitization of slightly hypereutectoid steels. In an extensive investigation of graphitization of high-purity iron-carbon alloys, Wells1 produced graphite at 7o0°C. (1290°F.) in an alloy containing as little as 0.13 per cent carbon, and showed that graphite may precipitate either directly from austenite or from decomposition of Fe3C, also that the rate of graphitization tends to increase with increase of temperature, at least up to a certain point, and with the presence of graphite nuclei. Jenkins, Mellor and Jenkinson,3 studying the structural changes in carbon steels ranging from 0.17 to 1.14 per cent carbon during stress-rupture tests at elevated temperature, obsenred graphite in an aluminum-killed 0.40 per cent carbon steel after fracture in 4340 hr. under a stress of 17,900 lb. per sq. in. at 840°F. and in many of the steels after stress-rupture test at 1200°F. Unstressed samples of 0.60, 0.86 and 1.14 per cent carbon steels graphitized almost completely in 360 hr. at 1200°F., while samples of 0.90 and 1.10 per cent carbon steels were somewhat graphitized, and steels containing 0.24, 0.40 and 0.57 per cent carbon showed no sign of graphite. Their results indicate that graphite precipitates the more readily the higher the carbon content, though this tendency is influenced to some extent by deoxidation practice, and that graphitization is accelerated by plastic deformation. In a recent study of the graphitization of 0.4 and 0.6 per cent carbon steel strip, made by M. A. Hughes,4 it was found that at 1200°F. graphite appeared after 72 hr. in aluminum-killed but not in silicon-killed steel, and that the rate of graphitization was increased by slow cooling from 1600°F. and by cold-working prior to annealing. In creep tests of normalized o. I 5 per cent carbon steel killed with 2.5 lb. of aluminum per ton, at the U. S. Steel Corporation laboratory at Kearny, spheroidization and some graphitization were found after 3000 hr. at 1000°F. under a stress as low as 15m lb. per sq. inch.

Jan 1, 1944

THE good and lofty men of intelligence are constantly discoverers of many beautiful things, because of their kindness or because they are driven by necessity. Either they shorten the method of making them after they have seen them, or they think how they can be increased in power or how they can be used for various effects in addition to the one intended by the inventor. Certainly all the effects described to you in this Tenth Book derive from gunpowder. When so many proper- ties and so much strength were observed in this, it was thought that by enclosing it in some strong thing that had the power to resist it, gunpowder would produce a marvelous effect. And thus they made a tube of bronze or iron [160v] which they closed with a wooden plug. They applied fire, and when they saw how forcefully this plug issued they thought of making one that would come out and strike in order to destroy things. They made an instrument of bronze or of iron and put some powder and a round stone inside, and called it a spingard. Developing then from this,

Jan 1, 1942

By Robin P. Gardner

Prior work by the author has established that closedform analytic solutions can be obtained for certain steady-state and transient types of operation of open circuit, continuous ball mills. This is possible when the tanks-in-series concept is used with the segregated flow or lumped parameter milling models. Such models should be useful (whenever they apply) in any calculational application since they are efficient and simple to program for digital computation. For example, they might be used within a computer program such as that developed by Herbst et al. for the calculation of model

Jan 1, 1975

By W. O. Philbrook, C. W. McCoy

The reduction of chromous oxide from lime silica alumina slags by carbon-saturated iron behaves as a first-order process having a rate of 0.001 grams Cr min 1 cm 2 (pct Cr ) , substantially independent of slag composition and temperature over an important range for iron smelting. The equilibrium ratio (pct Cr)/[pct Crl is below 0.04 for slags having lime-silica ratios above 0.6. MANY studies have been conducted on chromium in slag-metal systems under oxidized conditions. The Purpose of these investigations has been twofold; namely, (1) to determine those conditions which lead to greater chromium recovery in electric-furnace and open-hearth practice, and (2) to determine the nature of oxide inclusions and de-

Jan 1, 1959

By L. H. Ketchum, T. L. Theis, W. H. Engelmann

The use of a suspended growth system of Thiobacillus ferrooxidans attached in a film to individual particles of bentonite and operated as a sequencing batch reactor is shown to be a practical way of oxidizing ferrous iron in acid mine drainage. This component, followed by limestone neutralization, is both a technically and economically feasible approach to treating these waste waters, compared to existing and other proposed methods. The advantages, in addition to less expense, are greater safety, acceptable treatment at a lower pH, lower solids buildup, less danger of overtreatment, and greater flexibility in operational characteristics. In this paper, data on the continuous bench scale operation of the system under a variety of conditions shows sustained levels of oxidation in excess of 98%. Capital and operating costs are projected to be $80/1000 m3 ($80 per 35, 000 cu ft) of waste water.

Jan 1, 1985