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By Richard L. Ash

7.3-1. Introduction. All phases of mining competent materials are affected directly by the results achieved from primary blasts. It is imperative that their design suit each particular set of mining conditions. In general, the round design must provide an adequate tonnage of material, properly placed with suitable fragmentation, to ensure that loading, haulage, and subsequent disposal or processing are accomplished at the lowest possible cost. Blasting rounds are designed by the proper application of cratering relationships developed for the single, concentric, confined explosive charge. Blasting for surface mining and most open-cut heavy construction, however, is characterized by the use of rounds, composed of a number of explosive charges with relatively long lengths, which are placed in benches with specific finite dimensions. Therefore, modifications must be made to the classical, single point-charge cratering concepts. It is the purpose of this discussion to outline the basic principles, significant variables, and procedures for their integration in the design of rounds that are applicable to conditions characteristic of surface mining. Because relatively insensitive blasting agents will be used in most instances, particular attention must be given to priming, control of confinement, and selection of charge diameters that ensure complete explosive-reaction execution. 7.3-2. General Considerations. The primary requisites for any blasting round are that it ensure optimum results for existing operating conditions, possess adequate flexibility, and be relatively simple to employ. It is important that the relative arrangement of blastholes within a round be properly balanced to take advantage of the energy released by the explosives and the specific properties of the materials being blasted. There are also environ- mental and operational factors peculiar to each mine that will limit the choice of blasting patterns.

Jan 1, 1968

By Charles V. Riley

While the late 1960's are known as the years of the public recognition of impending environmental crises, the 1970's will be known as the decade of public concern for improving the quality of that environment. One of the major environmental concerns is the temporary disturbance resulting from coal surface or open cast mining. Increasing energy demands in the U.S., a doubling of electrical power consumption each decade during the present century and the projected needs for the remainder of the century are indications that coal surface mining as a major extractive industry will continue. Coal and lignite, prime energy resources and extremely abundant in these United States, in the face of seemingly limited gas, oil and uranium reserves, are both destined for expanded future use. Presently some extremely serious technological and environmental problems are associated with the development and use of nuclear power. It is true that the extraction and use of coal as an energy fuel poses disruptive problems for the environment, but the solutions to many of the problems are known or can he solved within a reasonable time framework Certainly our national well-being and continued survival as a free nation within the world community automatically dictate the continued use of the coal resource for energy. Concurrently, those engaged in coal surface mining, with the temporary disturbance of the land and water resources, must also realistically conclude that public concern for maintaining and improving the quality of the environment will not diminish. Although as ecological, economic, social and aesthetic elements of cost-benefits and human desires are more adequately understood, a more rational and reasonable public and governmental attitude hopefully will result.

Jan 3, 1973

By Charles Smeal, Robert J. Schafer, Max Quantinetz

Normally metal powders cannot be ground to sub-micron sizes because of welding and agglomeration phenomena. Through the use of selected grinding aids and grinding fluids, nickel and other metal powders have been ball-milled as fine as 0.1 It was found that certain inorganic salts are more effective grinding aids for metal powders than conventionally used surfactants. METAL and alloy powders are used to produce reagents, pigments, coatings, solders, brazes, and parts for industry by powder metallurgy techniques. They are also combined with refractory compounds to produce cermets and dispersion-hardened products. One of the interests at the Lewis Research Center has been to explore the potentialities of the dispersion strengthening process. Since the work of Ir-mann, many investigators have shown that the strength of dispersion-hardened products may increase with decreasing interparticle spacing.24 One approach to achieving small interparticle spacing is to combine fine refractory compounds and metal powders, preferably below 1 in size. In attempting to obtain fine metal powders, it was found that until very recently the best that could be obtained from commercial suppliers, particularly of ductile metals, was about 1.0 . Interest was therefore developed in providing finer metal powders for dispersion-hardening studies. Information obtained from the literature, from others working in the field, and from prior experimental work performed at NASA, led to a consideration of ball-milling as a technique to produce the desired materials. Some of the variables associated with ball-milling are the size, material, and nature of construction of the grinding container; the nature and amount of the grinding material and material to be ground; and the nature and amount of the grinding liquid and grinding aid, if employed, and the grinding time. In all ball-milling, welding and agglomeration can oc- cur as well as grinding. Because of the tendency of ductile metals to weld together, they are difficult to grind.5 The ultimate particle size obtained on grinding is generally the one at which the rate of grinding becomes equal to the rate of welding. To help delay welding and thus obtain smaller particle sizes, grinding aids are often employed. The principal objective of this investigation was to produce submicron metal powders by ball-milling the powders with selected grinding aids and grinding fluids. A secondary objective has been to attempt to explain the variations observed in grinding behavior by considering possible grinding mechanisms and correlating various parameters with grinding effectiveness. Three groups of ball-milling experiments were run; one in which the grinding aid was varied, a second in which the grinding fluid was varied, and a third in which the material being ground was varied MATERIALS, APPARATUS, AND PROCEDURE In the first group of experiments in which the grinding aid was varied Inco Carbonyl Grade B nickel powder initially 2.5 (all sizes refer to average particle size as measured by Fisher Sub -sieve Sizer) was used as the material being ground and 200-proof ethyl-alcohol as the grinding fluid. Surfactants, representative of typical organic structures, were selected as grinding aids. Inorganic salts used as grinding aids were chosen on the basis of the size and valence of their ions. Water soluble salts were used in order to facilitate their removal from the slurry after grinding. In the second set of experiments, grinding of the 2.5- Ni powder was tried in four different grinding liquids; water, cyclohexane, n -heptane, and methy-lene chloride. In this study seven grinding aids selected from those tried in the first group of experiments were employed. In the third group of experiments 200-proof ethyl alcohol was again used as the grinding fluid to mill Cu, Cr, Fe, Ag, and Ni powders of various initial particle sizes' All mill charges contained 300 ml of grinding liquid and 3000 g of 1/2 in. stainless steel balls. When inorganic salts were used as the grinding aid, 70 g of salt and 210 g of metal powder were employed, and with surfactants 6 g of grinding aid and 300 g of

Jan 1, 1962

By A. E. Hunt, G. P. Clapp

This paper constitutes in substance a part of a more elaborate chapter, accompanied with extended tables of analyses, prepared for the book of Mr. Fred. H. Whipple on " Water-Supply." In advanee of that use of the material, however, it seemed appropriate to lay a portion of it before the Institute; and this opinion of the authors, the Council, by accepting the paper, has ratified. It may seem at first glance, nevertheless, that a paper dealing chiefly with this subject in its sanitary aspects, and only treating in a subordinate way of the one subject (boiler-scale) usually deemed to concern our professions, is somewhat out of place in our Transactions. But reflection will, we trust, correct this impression. In recent periods, and in continually increasing degree, the managers

Jan 1, 1889

By Paul Weaver

OF the four papers that comprise this TECHNICAL PUBLICATION, three are case histories of individual geophysical prospects, subsequently tested by drilling. The bibliography of Dr. Barton's published scientific papers† includes investigaions in physiography and surface geological mapping, as well as his geophysical papers, and from this list it is to be observed that he early recognized the place of different types of geophysical prospecting methods in the search for geological structures of economic importance. Moreover, his viewpoint was not merely that the structures should be found, but that the geophysical data should be examined quantitatively to determine the geometry of the structures. In other words, that although these data are insufficient to deduce a unique form for the structure that caused the effects measured in the data, the engineering computations should be carried-out to give as much of a definite configuration to he structure as the data permitted, in order that the testing of the structures could be conducted in the most economical manner and with the idea that the experience so gained could be later incorporated in the study of structures subsequently found. Dr. Barton continually emphasized the quantitative use of geophysical observations, whereas at the time that he began his specialization in geophysics it was considered sufficient to use observations only qualitatively. He, more than any one else, was responsible for -the first volume on geophysical prospecting issued by the Institute in 1929, and his three articles in that volume stressed the quantitative use of geophysical prospecting. The fourth article in this present TECHNICAL PUBLICATION is a further contribution to this branch of geophysical interpretation, and is a supplement to the paper in the 1929 volume, "Calculations in the Interpretation of Observations with .the Eötvös Torsion Balance." From the successful' demonstration by Dr. Barton of the usefulness of quan-

Jan 1, 1944

By T. M. Geffen, R. E. Gladfelter

Lipson1 has recently presented a technical note wherein theoretical considerations were used to demonstrate. that the adsorption us saturation relation for a linear absorption method is not necessarily a single valued function of saturation.1 It was concluded that the absorption us saturation relationship is subject to the same hysteretic effect as is the flow behavior between the drainage and imbibition systems. It is the purpose of this note to show, by experimental results, that for the manner in which fluids are distributed in porous materials during fluid flow, the relative X-ray absorption us saturation relationship is single-valued regardless of the saturation history. The design of the apparatus used to measure relative X-ray absorption of cores undergoing fluid flow tests is similar to that described by Morgan, McDowell and Doty. A few modifications have been incorporated in the design to increase sensitivity and simplicity of measurement. The sensitivity is such that for usual types of cores a recording pen movement of approximately 12 linear in. is occasioned between the recording of the core dry and when it is completely full of an absorbing liquid, a solution of approximately five per cent by volume of iodo-benzene in a close-cut hydrocarbon fraction, or a solution of 50,000 ppm sodium iodide in water. Two types of experiments were conducted, one in which the liquid was inside the core, and the other with the liquid outside the core. Tests with the liquid inside the core were run to cover the saturation range encountered in both the drainage (gas drive) and imbibition (liquid flood) flow systems. It is pointed out that the same core was used, but the tests were conducted at different times with the recording mechanism balanced at a different position. Therefore, the absolute values of relative X-ray intensity at any saturation are not the same in each test. In the second type of test the same core was used, but this time its pore space cmtained only gas, and various thicknesses of oil contained in plastic cells were placed in front of the dry core. As before. the relative X-ray ah- sorption was measured and compared to the quantity of oil in front of the core. The arrangement of the fluids with respect to the path of X-rays in these two types of tests represent fluid distributions of a wider difference than can be expected between that established in a core just due to imbibition and drainage saturation flow histories. Thus any deviation from a straight line relationship of the log of the relative X-ray intensity us saturation calibration should be readily apparent. Results of the laboratory tests are given in Fig. 1. A schematic diagram showing the position of the fluids with respect to the path of the X-ray beam is given for the two cases investigated. In the case where the oil existed outside the core (Case B), the log of the X-ray intensity (log, I/I,) is related directly to the cell thickness (amount of oil in X-ray beam path). This correlation is in full agreement with X-ray theory. In the case where the oil or water existed inside the core (Case A) which covers both drainage and imbibition types of flow processes, again the relationship between absorption and saturation (amount of oil in X-ray beam path

Jan 1, 1952

By A. A. Rauth

In this paper, the author derives a series of formulas from basic principles and illustrates the application of these formulas to practical grinding charge problems. The paper establishes the nearly proportional relationship of mill power to charge level and shows how this relationship can be used to advantage in the design, manufacture and operation of grinding mills. The procedures outlined offer a rapid means of anticipating the power requirements for a given charge or determining makeup charges for a given power reading. The theories which have been developed concerning the dynamics of grinding have been motivated largely by the desire to derive workable formulas for the accurate determination of grinding mill power. This accurate determination has always been handicapped by the large number of variables to be considered, some of which are mill diameter, length, speed, liner design, grinding charge and material density, volumetric mill loading, internal friction, and charge size and gradation. In efforts to determine mill power, attempts have been made to utilize torque concepts. The formulas derived consider the grinding mass as a rigid body and utilize factors that are based on empirical data so that the movement of the charge within the mill is compensated for. These formulas are of principal interest to the mill designer since he is charged with the responsibility of analyzing all of the variables and from them predicting a mill size and a motor size which are compatible both with each other and with the grinding job for which they were intended. The mill operator, on the other hand, has an entirely different problem. The mill dimensions are already established and so is the driving motor. The operator's main concern is to obtain maximum performance from the mill he already has. For him, the many variables which perplex the mill designer are fixed values. Mill diameter, length and speed are set and, to a large extent, so are the conditions inside the mill from which the torque formula advocates derive their empirical data. It is conceivable that if the major mill dimensions which affect power demand are held constant, and if the variables influencing empirical factors are held fairly constant, as they are in an operating mill, then the only major variable remaining which affects power is the level of the charge itself. Under this condition.

Jan 1, 1970

By G. W. Josephson

Since the earliest years of recorded history the durability and protective qualities of asphalt and tar have been known and utilized. The mummies of early Egyptian kings were coated with asphaltic materials, and asphalt mastics were common in Babylon. However, according to various authorities, it was not until 1780 that the first forerunner of present-day composition roofing was discovered,l and the large-scale expansion of the industry has taken place since 1900. Historical Background Development was stimulated by the growing popularity of manufactured gas. The by-product tars from these operations accumulated in large waste piles that had no commercial value and were a source of annoyance and expense to the gas companies. These tars were offered at very attractive terms to anyone who would take them away, and the infant "composition" roofing industry benefited accordingly. At first the process consisted simply of dipping sheets of burlap or other fabric in a tank of molten tar or asphalt. The long strip of roofing was rolled up for convenient handling, and the early experimenters soon found that it was necessary to dust the surface of their new "roll roofing" with some kind of material that would prevent the tarred surfaces from sticking together. Any finely divided, low- priced local material like sand or fine gravel served this purpose and from its application the roofing-granule industry grew. As time went on other characteristics of a properly applied mineral surfacing were recognized. As with wooden shingles, tar and asphalt can be ignited by flying embers from near-by fires. It was found that by increasing the largest particle size to the maximum that could be successfully embedded, and by properly controlling the amount of smaller fractions retained in the grade so as to cover the asphalt completely a high degree of resistance to fire was attained. Needless to say, in this early period asphaltic roofing needed such selling points to gain acceptance in a field dominated by wood, slate, and tile. When asphalt is protected from the sun's rays it is extremely durable, but when exposed to sunlight its surface is comparatively rapidly decomposed. Completely covering asphalt roofing with mineral surfacing protects the asphalt and adds materially to the life of the roof—conservatively, 500 per cent. Slate Graftules In the production of split slate shingles a large quantity of waste slate is accumulated, as 60 to go per cent of the rock quarried is discarded. This waste was a continuing burden on the industry. Some was marketed as ground slate flour for filler in paint and linoleum, and there is a record that as early as 1906 two carloads of coarse screenings from slate flour were marketed as granules for surfacing roofing. This new field appeared to the slate Pro-

Jan 1, 1948

By G. W. Josephson

Since the earliest years of recorded history the durability and protective qualities of asphalt and tar have been known and utilized. The mummies of early Egyptian kings were coated with asphaltic materials, and asphalt mastics were common in Babylon. However, according to various authorities, it was not until 1780 that the first forerunner of present-day composition roofing was discovered,l and the large-scale expansion of the industry has taken place since 1900. Historical Background Development was stimulated by the growing popularity of manufactured gas. The by-product tars from these operations accumulated in large waste piles that had no commercial value and were a source of annoyance and expense to the gas companies. These tars were offered at very attractive terms to anyone who would take them away, and the infant "composition" roofing industry benefited accordingly. At first the process consisted simply of dipping sheets of burlap or other fabric in a tank of molten tar or asphalt. The long strip of roofing was rolled up for convenient handling, and the early experimenters soon found that it was necessary to dust the surface of their new "roll roofing" with some kind of material that would prevent the tarred surfaces from sticking together. Any finely divided, low- priced local material like sand or fine gravel served this purpose and from its application the roofing-granule industry grew. As time went on other characteristics of a properly applied mineral surfacing were recognized. As with wooden shingles, tar and asphalt can be ignited by flying embers from near-by fires. It was found that by increasing the largest particle size to the maximum that could be successfully embedded, and by properly controlling the amount of smaller fractions retained in the grade so as to cover the asphalt completely a high degree of resistance to fire was attained. Needless to say, in this early period asphaltic roofing needed such selling points to gain acceptance in a field dominated by wood, slate, and tile. When asphalt is protected from the sun's rays it is extremely durable, but when exposed to sunlight its surface is comparatively rapidly decomposed. Completely covering asphalt roofing with mineral surfacing protects the asphalt and adds materially to the life of the roof—conservatively, 500 per cent. Slate Graftules In the production of split slate shingles a large quantity of waste slate is accumulated, as 60 to go per cent of the rock quarried is discarded. This waste was a continuing burden on the industry. Some was marketed as ground slate flour for filler in paint and linoleum, and there is a record that as early as 1906 two carloads of coarse screenings from slate flour were marketed as granules for surfacing roofing. This new field appeared to the slate Pro-

Jan 1, 1948

By Arthur Gibson

Synopsis.-A new feature in coal mining, where the coal is to be conveyed from a high to a lower elevation and the topography of the country is such as to preclude surface haulage. The distance from the mine to the tipple inn this instance is about 3,000 ft. and the difference in elevation between the terminals 321 ft., of which 225 ft. occurs in the first 1,300 ft. from the loading terminal. A mine car was designed especially for this plant consisting of two tramway buckets on one pair of trucks, the buckets being lifted from the truck, attached to the train line automatically, and conveyed to the tipple. THROUGHOUT eastern Utah, in the Book Cliff range and the Wasatch plateau, the coal-bearing measures are admirably exposed, in the bold and for the most part bare escarpments. The geology is simple, the rocks being almost flat, or at the most dipping not more than 10 per cent. The coal beds occur in a formation, or group of strata, consisting of sandstone and shale, 600 to 800 ft. thick, which has been correlated with the Mesaverde formation of the Cretaceous. Above this occurs about 2,000 ft. of alternate layers of buff-colored sandstone and shale. Below the coal lie the Colorado shales, which are estimated to be about 1,500 ft. thick, below which are the red rocks of the Jura-Trias. As a rule the coal beds all clip in a northerly direction and under the high mountain. The canyons opening out into what is known as Castle valley all cut the coal beds, and the beds rising in the direction of the valley are found frequently high up on the escarpment, often as much as 1,000 ft. above the valley. The surface features of the region have an economic bearing on the availability of the coal. The valleys and gulches in the Colorado shale extend out from the coal areas across the edge of the plain, so that it is impracticable to build transportation lines parallel with the boundaries of the field within several miles of the coal land. It will be necessary, therefore, to build branch lines up to the coal lands from points on the Denver & Rio Grande Railroad traversing Castle valley.

Jan 10, 1914

By Jack White, Ralph B. Adair

THE Mufulira mine in Northern Rhodesia is 13° south of the Equator and at an altitude of 4100 ft above sea level. The concentrator was planned in 1930 to treat about 10,000 tons of ore per day, but before construction work had gone very far the size of the plant was reduced to 1500 tons daily capacity. Then just as the construction was finished in December 1931, the price of copper did not warrant the commencement of operations and it was not until October 1933 that the mine re-opened. Extensions have been made to the plant in 1034, 1935, 1936 1937, 1940 and finally in 1945. The capacity of the plant when the 1945 extension is completed will be 9500 short tons per day. The various extensions have been carried out with the minimum confusion and with great skill on the part of the designers and the erection engineers. In dealing with the plant in this paper it is proposed to give an outline of the present practice and only to refer to past practice when it is considered of particular interest. ORE TREATED The ore consists of fine grained highly siliceous, felspathic and argillaceous quartzites, the latter containing graphitic carbon and locally termed graywacke. These rocks are considerably altered near the surface and on the fringes of the ore body. Despite extensive efforts at mixing, both underground and in the crushing plant, many sudden changes of ore take place in the mill feed. The minerals are chalcocite, bornite and chalcopyrite with relatively unimportant amounts of malachite, native copper, azurite, covellite and chrysocolla. Gold is present at about 1 oz to a thousand tons, and silver at about 2 dwt. per ton. With increasing depth the nonsulphide content or, as commonly termed locally, the oxide content of the ore is decreasing and is now less than 0.25 pct against a high of 0.77 pct. CRUSHING OPERATIONS The first stage of crushing is done underground where the oversize from 12-in. grizzleys is fed to a 56 X 72-in. jaw crusher. At the Selkirk shaft two 10-ton skips deliver the run of mine ore at a rate of 450 tons per hour to the 400-ton capacity shaft bins. One 6 ft wide Ross chain feeder and one locally made air-operated finger feeder feed the two 30-in. McCully crushers. Ahead of each crusher is a 6 X 9-ft spring grizzley spaced at 5 in. on a 35° slope. Neither the Ross chain feeder nor the finger feeder is entirely satisfactory and for the wet, muddy and sticky ore that has to be handled it is planned to replace these with two 6-ft wide apron pan feeders. The McCully crushers deliver a minus 5-in. product, at a rate of over 500 tons per

Jan 1, 1947

By L. Adler

A relatively simple and effective technique is proposed to deal with the failure of geologic masses containing weakness planes. This technique, termed irextended" rupture envelope, provides a means to clearly distinguish rock and soil from fractured rock and, on a theoretical level, considers a matrix-inclusion system. It may also constitute the link between Mohr's and Griffith's failure theories. Included in the article are five sample problems concerning site location, structural design, strengthening the plane of weakness, changing the magnitudes of major and minor principal stresses and changing the orientations of major and minor principal stresses. Engineers trying to solve design problems in rock and soil mechanics have often assumed an iso-tropic and homogeneous medium. For naturally occurring geologic masses this assumption has always been viewed with regret. The following analysis which deals with the effects of plane anisotropy on failure presents a solution to this. The planes of weakness are joints, faults, bedding planes, fracture and cleavage (natural and induced), foliation and schistosity. The physical properties of these weakness planes include an undulating surface, frictional resistance, discontinuous extent, filling material, tightness and presence of water to cause a hydrostatic pore pressure. All of these properties relating to failure can be summarized in Mohr's rupture envelope for the plane of weakness. This, along with the geometrical orientation, strike and dip, of the plane of weakness produces what is termed an irextended" rupture envelope. MOHR'S STRESS CIRCLE AND RUPTURE ENVELOPE The significant features of these concepts are listed below.' 1) A point on the u - r coordinate plane represents the normal and tangential stress components on a reference area in the material. This area can have any orientation. (Fig. la)

Jan 1, 1963

(The paper by L. H. De Wald-Tech. Pub. No. 429 was presented at the Boston meeting, September, 1931.) W. A. SCHEUCH, Chicago, Ill.-Since starting up our Hawthorne copper wire plant we have found that wire bars from certain suppliers perform quite differently from those of other suppliers. In attempting to evaluate these bars, we made cross-sections, and in making these cross-sections we found considerable variation in the crystal structure. Indications were that there was some preference in the type of crystal structure. In attempting to find the reason for that we discussed it with the various producers and-also reviewed the literature. Mr. DeWald was assigned to determine the various factors that enter into copper wire bar crystal structure, on the basis that the product was a horizontally cast wire bar of practically identical composition and of recognized good composition for the present quality product sold in the market. Mr. DeWald has asked me to say that he should have made reference to Mr. Dalzell's paper on a theory concerning gases in refined copper. D. K. CRAMPTON, Marion, Conn. (written discussion).-Mr. DeWald has set forth an interesting and thorough exposition of the factors controlling macrostructure of this material. It is particularly interesting to us as it somewhat parallels work we have done on macrostructure of round copper billets for piercing into tubes. Our findings as to the effect of the several variables on macrostructure check Mr. DeWald's. The general principles underlying the two are precisely the same. The fact that we worked with copper deoxidized with phosphorous instead of tough-pitch copper, and round billets cast on end instead of wire bars, does not influence the results. We have found that round billets cast so as to produce large radial grains have greater soundness and density than those with a fine macrostructure. Further, and more important, we have found that the billets with large radial grains show markedly different performance on piercing from those having a fine equiaxed structure. With a given temperature of billet and adjustment of piercing machine, the coarse-grained material requires appreciably lower power for piercing and goes through the operation inn appreciably less time. These two differences are of sufficient commercial importance to warrant exercise of great care in maintaining the coarse structure. It seems probable that much the same phenomenon should hold in the hot rolling of tough-pitch wire bars. We would expect that, other things being equal, the coarse-grained wire bars would roll more readily and require less power than fine-grained ones. Moreover, we believe the differences in initial structure of the wire bars should be largely eliminated in the hot rolling process and during the subsequent drawing and annealing, of wire would be entirely eradicated.

Jan 1, 1932

By Anson Hayes

THE quality of sheet and strip products made of rimming steel is closely related to the structure and chemistry of the ingots. The varia-tion in composition throughout the ingot, as affected by segregation, is of great importance, as are also the form and distribution of the voids that result from the gases evolved. It is because of this importance that the considerable literature in this field has accumulated. No attempt is made in the present paper to compile a bibliography of the excellent work that has already been done, as this has been adequately covered in the many excellent reports on the heterogeneity of steel ingots prepared by a joint committee and published by the British Iron and Steel Institute.1 From time to time, in any field of investigation new tools and new technique are developed, which make further progress possible. In the field with which this paper is concerned, this is true. The development of the vacuum-fusion method as a means of following oxygen segregation, and a technique for obtaining the volume and composition of the gases evolved during solidification, have opened the way to obtaining data by means of which some considerable progress has been realized in developing more of the detailed mechanisms of solidification and segregation in rimming-steel ingots.

Jan 1, 1938

By Stanley J. LeFond

Jan 1, 1985

By Frank H. Riddle, Wilfrid R. Foster

GENERAL treatment of the various minerals of importance in refractories appears in the chapter entitled "Refractories" elsewhere in this volume. The present chapter is restricted to a discussion of minerals of the sillimanite group and brings up to date the excellent information contributed by Prof. Paul F. Kerr to the first edition (1937). Since the appearance of that edition, the status of the group has changed some- what. Kyanite remains the preferred source material for mullite refractories but total consumption of kyanite has increased considerably.85 The exigencies of World War II forced an increased dependence on domestic sources and led to an intensification of the search for higher-grade deposits of kyanite and allied minerals. The first discovery of massive kyanite similar to that of India has been reported from Georgia.37 British East Africa has joined India as a substantial supplier of our imported kyanite, but that from India continues to hold preference.85 During World War II, prices of both domestic and foreign grades reached peaks unparalleled since the earliest years of the use of kyanite and as yet have shown no tendency to return to prewar levels. Topaz, by virtue of the deposit outlined in South Carolina, merits inclusion in the group.20,36,95 Large andalusite deposits, which threaten to rival our one large domestic occurrence, have been found in Russia.69,88 Sillimanite has not yet attained an important position among these useful minerals because of the lack of accessible deposits of high-quality material in adequate supply.37,50,58 Tests by the Bureau of Mines have indicated the possibilities of economically beneficiating low-grade sillimanite and kyanite.105.106,140 Government, university, and industrial

Jan 1, 1949

By Evan Just

THE high standards of living and improved national security that industrialization can bring are so evident that no country can be named that does not cherish the hope of industrializing. With such a universal aim, why do many countries unable to develop their own industries accomplish so little toward attracting the foreign private investor, who alone can provide them with the necessary capital and skill? Obviously, because they fail to under- stand what constitutes a favorable climate for investment, because they have false notions about being exploited or dominated by the foreign investor, or because they are so nationalistic they refuse to permit outside assistance. The purpose of this paper is to aid the citizens and policy makers of developing countries in achieving their aims, by defining the conditions which en- courage investment and portraying the results of a policy of encouragement. The following is quoted from Eugene R. Black, president of the World Bank:

Jan 6, 1957

Jan 1, 1903

By E. A. Lucero, H. E. Robbins, T. H. Dudley

EL Salvador mine of Andes Copper Mining Co., E subsidiary of Anaconda Co., is in northern Chile about 18 miles north of Potrerillos, 7825 ft above sea level. Initial production is planned for the first half of 1959. Plant capacity will be 30,000 tpd, and there are 308,835,000 tons of proven ore reserves, averaging 1.49 pct Cu. The Inca adit is being driven as part of the mine-to-mill haulageway. Because of the overburden it is planned to mine the deposit by block caving. Ore will be dropped from upper gathering levels through ore passes to the Inca adit, through which it will be transported out of the mine to the primary crushing plant located a half mile from the portal.

Jan 3, 1958

By Charles Miller

Natural carbon dioxide has recently been exploited in the United States in consequence of oil and gas developments in the Western States and the growing demand by transcontinental and transoceanic shippers for solid carbon dioxide. The discovery by drilling of commercial deposits resulted in consideration of its geographic and geologic distribution and occurrence. Its wide distribution in nature is evidenced by its occurrence in the atmosphere, hydrosphere and lithosphere. The question of origin of carbon dioxide involves consideration of theories similar to those concerning natural hydrocarbons, although available evidence favors an inorganic rather than an organic source. Areas favorable to development of commercial production appear to be those in proximity to igneous rocks or in the vicinity of decadent volcanic activity, where, it has long been known, the gas is evolved either free or dissolved in the waters of fumaroles, geysers or mud pots. Structure contour maps are presented showing the Wagon Mound anticline in New Mcxico and the Farnham anticline, Utah. A well drilled on the latter supplies gas to a 20-ton plant manufacturing solid curbon dioxide at Wellington, Utah, on the Denver and Rio Grande R.R., whence it is shipped to surrounding territory and to the West Coast. Before funds are invested in a plant for the manufacture of liquid or solid carbon dioxide, whether supplied by wells or springs, an effort to ascertain the volume of gas available is advisable. The use of present methods of estimation of gas reserves with modifications to account for the quantity absorbed by any water present in the producing formation is recommended. The Farnham anticline is used as an example and computations are made of the probable volume of gas originally present in the structure. No attempt was made to compute reserves in the Niland area, California, for the reason that in such areas it is believed the volume is indeterminate. Introduction Carbon dioxide, in liquid and solid form, has found a wide variety of uses other than its primary application in carbonating beverages. It is now used in more than 40 different ways, ranging from cooling or freezing to use in gas or liquid form for mechanical purposes, chemical industry, explosive, fire extinction, and tire manufacturing. Undoubtedly the chief supply of carbon dioxide is obtained from industrial plants or artificial sources and until recently natural deposits of the gas have received little consideration. Few will question the utility and perhaps dependability of artificial sources, which possess the advantage over

Jan 1, 1938