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By Henry N. McCarl

[The Construction Materials section contains the following Chapters: Aggregates Cement and Cement Raw Materials Crushed Stone Dimension and Cut Stone Lightweight Aggregates Gypsum and Anhydrite Sand and Gravel Insulating Materials-Thermal and Sound Slag Roofing Granules] Mineral aggregates are those natural and manufactured industrial mineral and rock materials that provide bulk and strength in portland cement concrete, bituminous concrete mixes, and plaster or stucco surfaces. They may also provide special characteristics such as thermal and acoustical insulation, weight, surface textures, abrasion resistance, and impermeability to various concrete products and mixes. Most aggregates are relatively inexpensive materials, but despite their low unit value, the tonnages consumed each year in the United States and throughout the" world make mineral aggregates by far the leading industrial mineral and rock materials both in terms of volume (tonnage) produced and value consumed. The major use of mineral aggregates is in concrete. The low cost, high bulk aggregates tend to keep concrete construction costs at levels competitive with other building materials. Other major uses of aggregates include highway and railroad base or ballast materials, graded fill, and various industrial uses such as metallurgical and chemical fluxes and raw materials-these latter uses are often considered nonaggregate uses of mineral aggregate materials. The per-ton value of mineral aggregate materials at the production plant in 1980 and 1981 varied from $2 to $5 for most sand and gravel and crushed stone, $3 to $6 for air-cooled slag, $7 to $20 for expanded slag and expanded clay or shale aggregate, to as much as $165 to $320 for expanded perlite or vermiculite. The expanded lightweight aggregates have been dramatically affected by increasing fuel costs. It is ironic that the specialized aggregates used as insulating materials to conserve energy cost so much more to produce due to the high proportion of energy consumed in their production. The first four parts of "Construction Materials" deal with the utilization of four major mineral aggregate types: Crushed Stone, Lightweight Aggregates, Sand and Gravel, and Slag. While the focus will be on the use of these industrial minerals and rocks, there will also be some coverage of sources, mining and production, especially in those cases where they are not discussed in the Commodity section of this book.

Jan 1, 1983

By Charles S. Barrett, Robert F. Mehl

It is generally understood by workers in the field of the crystal structure of metallic alloys that terminal solid solutions are of two types, the substitutional and the interstitial. In reviewing the literature, the work of Weissl on the crystal structure of the alpha copper-tin alloys was encountered, in which a new type of terminal solid solution was proposed. In brief, Weiss' findings showed that the density of the alloys calculated from the side of the unit face-centered cube on the assumption of simple substitution—that is, with four atoms to the unit face-centered cell—was much higher than the density measured directly. It was suggested that the assumption of four atoms to the unit cube is not valid for these alloys, and that each unit cube contained less than four atoms; in other words, that one tin atom replaces more than one copper atom, leaving some atomic positions unoccupied. Such a structure, if verified, would have far-reaching significance in the study of the crystal structure of metallic alloys. It would indicate a complexity in terminal solid solutions not hitherto suspected and might encourage work leading to the discovery of other alloys of the same type, and perhaps to types intermediate between it and the two recognized types. It is of importance, therefore, to reinvestigate these alloys with respect to the type of solid-solution structure obtaining therein. Materials and Experimental Method The alloys were prepared from electrolytic copper cut directly from the cathode and the high-purity tin furnished by the U. S. Bureau of Standards for the calibration of thermocouples. No analyses for impurities of these materials or of the finished alloys were made, since such impurities as might be present could have only a wholly inappreciable effect upon the data obtained and the conclusions drawn. The alloys were made by melting the weighed copper charge in a graphite crucible under a KCl-LiC1 flux with later additions of NaC1, using induction heating. When the copper was melted the weighed portions of tin were

Jan 1, 1930

By R. L. Langenheim

Cooperative education for engineers is based on the premise that theory and practice are inseparable in training men for the engineering profession, and the two must be advanced simultaneously in order to train men most successfully and efficiently. The teaching of theory obviously should be done by the college but the practice must be obtained in the field where the application of the theory is made. The ideally trained engineer is one that knows theory, can apply the theory to practice, can direct, and work with, his fellow men. The old four-year plan of training engineers does a fair job of teaching the underlying theory of engineering but neglects entirely the training necessary for application of the theory, except through laboratory experiments, and the training in adjustments necessary to direct and work with men. An engineer, like a lawyer, doctor, dentist or other professionally trained man, cannot practice until he has had practical experiences that give him a knowledge of the other phases of his profession. The doctor serves as an interne, the lawyer reads law in the office of a practicing attorney, and the engineer must enter the profession as a laborer or as an apprentice, unless he has had the advantage of a cooperative education. Cooperative education provides the opportunity for the coordination of practical and theoretical training for the engineering profession throughout the period of training and thus eliminates many that are unfit to enter the profession, giving them an opportunity to seek other fields for which they may be better fitted, and reduces the overhead in industry that results from a large turnover of men not fitted for the profession. The Cooperative Plan Cooperative education in engineering is no longer an experiment. It was inaugurated at the University of Cincinnati in 1904 by Dean Herman Schneider, and has worked successfully ever since. Over twenty schools offer this type of education and many thousands of young men have had the opportunity to receive their technical training under this plan. Under the cooperative plan a student attends class for a period of eight weeks, then enters industry for eight weeks, maintaining this schedule

Jan 1, 1937

THE second operation in the art of casting, and one of the greatest importance, is that of melting and thoroughly liquefying the materials of which you wish to make your casting. On this operation depends the whole outcome of your intentions and the perfection of your work. Without it, even though you had a great abundance of moulds and vast quantities of bronze, your desires, labor, and expense would all be in vain. In this operation I find on consideration that, in addition to experience, there are three necessities-perhaps indeed four-that must be provided without fail. The first is the furnace or other agent which contains the fire and the metal brought together. The second is the wood or charcoal which is the necessary and proper nutriment of the fire, from whose virtues are derived the greater or lesser forces which, according to their kind, are ready to effect what is required. The third is to have the materials disposed to easy fusion by means of corruption, alloying, or by their own nature. The fourth, as the motivating cause of the whole, could perhaps be listed as the first-this is the ingenuity and good judgment of the worker, together with the bodily exertions not only of himself but also of his helpers in addition. For, besides a certain ordinary caution, it is necessary to pay particular attention, first, to see that the furnaces, machines, ladles, hearths, refineries, and other kinds of instruments or similar vessels be made so as to dispose the metals for melting, and, when melted, that they easily maintain them so. These should also be prepared in such a way that they cannot be injured by the fire, for if they should be damaged the operation would fail. In order to do this, it is first necessary that you arrange the instruments with forethought and action so that the power of the fire can operate. Fire operates on things only when brought together with them in long-continued operation, or when driven by a great force of wind. It burns many things and softens others, but it makes the metals as liquid as water.

Jan 1, 1942

By V 7. 0 / 300 dpi

THE cams at present universally used in stamp mills lift the tappets with an involute form of curve, to which the surface of the tappet is always tangent; moreover, the line of contact between tappet and cam, if produced, would pass through the center of the stem. This is no doubt a desirable feature, but the writer has long believed that it would be much more desirable if the cam were to pick up the stamp without shock, and gradually increase the upward velocity of the stamp throughout its upward movement. The involute form of cam attempts to impart instantly a considerable upward velocity to the stamp, starting it from a state of rest, and the result is a destructive blow, a great deal of noise, and much wear and vibration. The writer has developed a form of cam which will lift the stamp with a motion similar to that of the piston of an engine between the end and middle of its stroke; in other words, harmonic motion, from the point. of zero to maximum velocity. The curve will give this ideal motion only when the stamp is set for the exact drop for which the cam was designed, but the improved cam will not be as bad as the involute cam until the drop is reduced one-half. In other words, if a cam is designed for a 6-in. drop, it will be some improvement over the usual form of cam until the drop is only 3 in. Any cam, whatever its form, must of course lift the stamp in the same number of degrees of revolution; therefore, with this new form, since the stamp starts more slowly on its upward course, it must end up by going faster, the average speed being the same as with the involute cam. The stamp, after it is no longer in contact with the cam, keeps on going up a certain distance, which is easily calculated. It is therefore possible to hang up a stamp without a cam stick, if the fingers are not more than 1/8 in. longer than necessary to hold the tappet above the cam.

Jan 12, 1914

By James T. B. Ives

The map exhibited* as an example of my method of construct ing geological strata-maps is essentially an educational appliance. The method, however, is available for the production of maps of comparatively small areas, which, I am confident, will be found of great practical value to mining engineers. Before stating how the method may be so applied I will briefly describe the map exhibited, as the easiest way of making my meaning clear. Almost any region might be taken. This map represents the eastern half of the United States; and the geology is that of the map issued by the Geological Survey, and revised and extended subsequently by Professor Hitchcock for your Institute. I use ten cards, of the colors used in the geological map, each having the geog raphy of the area printed upon it; and I superimpose these in the order in which the colors occur in the index to the map. I next cut away a portion of each card, excepting the lowest, leaving only so much of each as represents the exposure of the formation of that color plus all those which overlie it. When that is done, the whole, looked at from a distance, appears to be an ordinary geological map. Looked at more closely, however, the formations are seen to overlie one another, as in nature. The cards are covered with glass in a frame, which, hinged at the bottom edge, can be let down. The cards are then found to be all hinged in the same manner, and they, too, may be lowered, one after the-other. I am told by teachers of geology of great experience and the highest reputation that by this appliance they will be assisted in im parting to students the first facts and principles of geological sci ence. Having let down the whole series of cards, until that repre senting the Archaean is seen underlying all the rest, the teacher will gradually rebuild it. The Cambrian will thus be laid down upon the Archaean before the eyes of the class, the Silurian upon that,

Jan 1, 1888

Air-sand Process of Cleaning Coal Discussion of paper by THOMAS FRASER and H. F. YANCEY, presented at the New York Meeting, 1926, and issued, as Pamphlet No. 1561-F, with MINING AND METALLURGY, February, 1926. T. DEVENNY, Edgarton, W. Va.-How near the size of the sand can the coal to be treated be brought? Do you use an 8-mesh coal on that cleaner? J. J. RUTLEDGE, Baltimore, Md.-From the little I have seen of the apparatus in operation, I should say 8-mesh. In my experience in metalmine concentration work, trying to separate different minerals on one jig, sometimes I have succeeded and sometimes not. This apparatus has appealed to me; something of this kind should be useful with the silicates and carbonates of zinc. I think this apparatus has possibilities in metal mining. Recently in our coal field a screen has been introduced for cleaning coal; it is giving excellent service. When I asked the inventor why he did not take it to the metal mines, he said there was a good and sufficient reason, in a patent way. There may be reasons why it would not be applicable for metal mining; but the simplicity of it appeals to me and I cannot see why it could not be so used. T. FRASER (written discussion).-We feel that 8-mesh would be about -the minimum size of coal practicable to treat by the air-sand process. This would depend partly upon the friability of the coal. The more nearly the lower size limits of the coal- approaches the size of the sand, the more .time will be required in screening the sand out of the cleaned coal, which would mean a little more chance of breakage. In regard to the treatment of ores; this would necessitate the use of some heavier mediums than ordinary silica sand, or some other means of making the separation at a higher specific gravity than is required for coal. We are now working on a method of obtaining this effect for the preparation of anthracite coal without resorting to the use of heavier and more expensive material than common sand.

Jan 1, 1927

By Benj. E. Shackelford

THE present paper is concerned with typical temperature values experienced in lamp-filament measurements as made on regular factory and engineering products. It deals with the relations existing between temperature, efficiency, lamp size, and life of incandescent lamps, insofar as they affect the rating of the product and its use by the individual consumer. The temperatures measured lie in that range covered only by the general method of radiation pyrometry, as opposed to direct methods used under contact conditions. The range of temperatures ordinarily experienced extends from about 2125° K., for the now almost extinct carbon-filament lamp, to 3200° K. for the comparatively new tungsten-filament motion-picture lamp. Most of the more common sizes of tungsten lamps have temperatures ranging from 2500 to 3000° K. Because of the high temperatures involved and the relatively small area of the sources used, we are practically restricted to two methods of measurement, both of which depend on the light radiated front the filament. The first and more usual method is that of the Morse pyrometer, dependent on the variation in temperature of the amount of light of a given color range yielded by the filament. In this case, the measured temperature is that of a small part of the incandescent body, that is, the part which is focused on the comparison filament. The second method, known usually in this country as that of "color match" and in England as "color-identity" is based on the color of the total light yielded by the filament, the comparison being facilitated by the use of an ordinary photometer- head. A more definite idea of the temperatures involved in the case of filaments of various vacuum and gas-filled lamps, is given by Fig. 1. The size of the lamp, in watts, is plotted along the horizontal axis and the temperature of the filament is plotted along the vertical axis. The lamps concerned are regular product, rated for 1000 hr. life. The temperature values for the old 16-candlepower carbon lamp and the new motion-picture lamp are shown by the cross and circle respectively.

Jan 9, 1919

By C. F. Cockrell, K. K. Humphreys, H. E. Shajer

It is quite conceivable that the question of using coal or an alternate fuel in the future by large industrial consumers may be decided on the basis of possible profitable utilization of flyash. Accordingly, the Coal Research Bureau at West Virginia University has been attempting to develop new uses for this waste material. This effort has resulted in the development of a process for producing flyash-based face brick and other structural materials which generally exceed published specifications for competitive clay-based materials. These structural materials, containing up to 97% waste coal ash, can be produced from flyash derived from most coals without regard to the physical or chemical properties of the coal ash. Preliminary production cost estimates indicate that face brick can be manufactured at a rate of 9000 brick per hr or more with a resultant gross profit of over $24.00 per thousand brick. Plant payout time for a plant of this size would be only about 1.2 years assuming a market price of approximately $55.00 per thousand, a well established figure for comparable clay brick. With flyash production expected to more than double in the next 15 years, there is an increasing need for a practical and Profitable method for the utilization of large tonnages of this material (see Table I listing total flyash production of utilities in each state of the U.S.). Present industrial and governmental physical and chemical restrictions, particularly for use as a lightweight filler or pozzolanic material, have limited the use of flyash considerably. For those ashes which have met the required standards, utilization is not always assured because of lack of promotion and poor public acceptance. Less than 6% of the total flyash production in the U.S. was sold in 1962. The remainder was dumped in disposal areas at costs as high as $2.42 per ton.' It is quite conceivable that in the near future the question of using coal or an alternate fuel by large industrial consumers may be decided on the basis of the possible utilization of flyash. To help insure future coal demands, the Coal Research Bureau at

Jan 1, 1968

By F. D. Mahone

Much crude oil, as produced from the well, carries varying amounts of water, which may be present as free water in globules sufficiently large to settle out, in time, if the fluid is allowed to stand, or as an emulsion formed by myriads of minute water particles, each surrounded and entrapped by a film of oil through which it cannot break under the action of gravity alone. Such an emulsified mixture of oil and water is commonly termed "cut oil." When such an emulsion is subjected, under proper conditions, to the influence of a high-potential alternating-current field, the minute water particles rupture the enveloping oil films and coalesce into larger water droplets this procedure continuing until all the water is freed into drops of such size that they readily settle out. This action has been photographed by the micro-moving-picture camera; under the microscope, the breaking-up of the emulsion, as described, is seen to be accomplished in a few seconds. The low power requirements of the process, from records of commercial plants, substantiate the theory that the action is that of a multitude of electrical condensers in series, rather than that of a number of conducting paths. The minute water particles serve as the metallic elements, or plates, of the condensers and the separating oil acts as the dielectric. Such surface charges as the particles may have are removed, and the intervening oil is broken, probably electrically by the voltage and mechanically by the attractive force between adjacent oppositely electrified particles. The principle of breaking up an emulsion under the influence of an alternating electric field was discovered by F. G. Cottrell and Buckner Speed, through experiments conducted, at the University of California, which resulted in a plant being installed on the property of the Lucile Oil Co. in the Coalinga field, California, early in 1909. This plant was able to reduce 14-per cent. emulsion to less than Pper cent. with commercial success. Standard Cottrell Apparatus The present standard Cottrell apparatus consists essentially of the electric treater and a settling or trap tank. The treater is a galvanized-iron tank approximately 3 ft. in diameter and 10 ft. high, which con-

Jan 1, 1924

By Frank Alfred Fahrenwald

Discussion of the paper of FRANK ALFRED FAHRENWALD, presented at the New York meeting, February, 1916, and printed in Bulletin No. 109, January, 1916, pp. 103 to 149. F. A. FAHRENWALD, Cleveland, Ohio (communication to the Secretary*).-Since the publication of my paper in the January Bulletin, (which was largely a metallographic treatise), I have been questioned regarding two points referred to therein. One of these is that which deals with the application I have made, p. 119, of the equation for melting pressures which correspond with different working temperatures. The other refers to the statement, p. 137, that "Prolonged heating at relatively low temperatures gave fewer and larger crystals and crystals of different sizes, while a flashing at higher temperatures gave a very fine and uniform crystalline structure, which was much' to be preferred." Especial emphasis was not placed upon either of these two factors, for each seemed perfectly logical and obvious. As they do not seem to be self-explanatory, I will supplement with those portions of my notes which were purposely omitted from the manuscript submitted for publication. A few practical illustrations may serve as evidence in support of the first of these, but it must be understood that in this work the "amorphous theory" is considered as being sound, and that it is assumed that metals allow of distortion, without fracture, by virtue of the formation of slip surfaces, accompanied by the transformation of crystalline material to the, amorphous phase. Effect of Pressure.-In all forging, rolling, and drawing operations, it is known that specimens of small cross-section may be worked at a lower temperature than can be used for the same material in much greater mass and sectional area. In -the larger pieces the maximum pressure is brought to bear upon the material near the surface, so that the interior is not subjected to great pressure, but to, a stress more nearly tensile, or shearing, so only the surface is subjected to the critical melting pressure. In the case of wires which draw hollow, the center is subjected to practically a tensile stress which breaks it, while the surface skin draws perfectly, due to the enormous "flowing" pressure exerted upon it by the surface of the draw-plate.

Jan 5, 1916

IF you wish to make the acid that is vulgarly called common aqua fortis,* for parting gold from silver, you must first provide as many cucurbits and alembics, receivers, and materials as you wish, and then make a furnace that is long and conveniently wide for holding three or four pairs of cucurbits or as many as you wish. If you have to make this by art in order to work a large quantity, you could make several small furnaces for it seems that not more than three or four pairs are suitable for one. Prepare the places where the cucurbits are to stand with bottoms or covers made of potter's clay or tiles that are half round like the bottoms of the cucurbits and have a little rim around the top so that they can be built in. Proceed to build these in in pairs, one by the other with convenient spaces between, placing an iron support across to make this place stronger and more secure. In every corner and also in the middle a hole must be made as a vent for the smoke, as is done in all furnaces. You will see the form of this somewhat roughly drawn here. [Figure 25] Near this prepare a number of cucurbits which are made of glass, as clear and uniform as possible and very well formed. There must be no bubbles or other indentations in these, for they would be dangerous and uncertain for your work. Lute these with lutum sapientiae up to within three dita or less from where the neck narrows. This lute must be spread out well all over to the thickness of two threads or a little more. Then cover and make them strong with this well-made plaster, and finally dry it, taking care that there are no clefts or cracks such as clays are often prone to make even though they be well prepared. For greater security choose among these [64v] a clay that is lean and then mix it with at least a fourth part or more of wool-clloth clippings and about an eighth part of wash

Jan 1, 1942

By A. C. Veatch

THE MIDLANDS of England contain large areas of important oil lands, which, however, will not become of commercial importance for at least 5 years, because the ownership of the oil has become a political issue. In Great Britain, except in certain special areas, all minerals, except for gold and silver, belong to the surface owner. The leasing of minerals on the large estates is a very complicated business, as the family solicitors have many forms and formalities that must be observed. In the case of one of the large estates, the principal revenues of which for several hundred years have been from coal leases, the average time between the agreement on terms for a coal lease and the signing of the same has been 8 years. In 1916, one coal lease on this estate had been pending for 15 years, and was still unsigned, although the important terms had been agreed upon 15 years previously. Under war conditions, and considering the extreme importance that the production of petroleum in England would have had, such delays could not be tolerated. Most of the British landlords, relying on the almost, universal opinion of their own countrymen that there were no commercial deposits of petroleum in Great Britain, were prepared to give all their oil rights to the government, but they feared that such action might establish a precedent with respect to coal. For years the Labor Party and extreme radicals have protested against the payment of royalties to landlords on coal. The government, therefore, introduced a bill taking over all the oil rights and providing for the payment of a small royalty to the landlords, to safeguard the principle of compensation in case the coal mines should ever be nationalized. The provision of this bill, with respect to the payment of royalty to landlords, was defeated by a vote of 44 to 35 in a night session of the House of Commons on Oct. 25, 1917, when most of the members were absent, but when a group of labor members and extreme radicals were present. The resubmission of the point to the House of Commons was prevented by the labor members of the coalition government, who reminded the cabinet that the agreement

Jan 1, 1920

By J. A. Solomon, H. E. Shafer

As a result of the great demand for metallic aluminum and the scarcity of domestic bauxite, numerous processes have been proposed and developed to extract the oxide of this metal (Al2o3) from clays, shales, and other low-grade raw materials.1-4 An exploratory study was made to extract alumina with sulfuric acid from relatively impure coal-associated draw-slate and to establish an optimum calcination temperature for maximum recovery. Draw-slate is the term used to describe the hard, slaty material directly overlying many coal seams and may range from a few inches to a few feet in thickness. Alumina content of these draw-slates may range from as low as 15% to over 35%. Although the following results are limited in scope, some of the data should prove beneficial for further work. Coal-associated clay, shale, and gob heretofore have been considered nuisance products; any successful alumina extraction process would greatly enhance the worth of these almost limitless resources. This research demonstrated that an optimum calcination temperature for alumina extraction could be established for a coal-associated draw-slate and that this temperature was lower than those suggested in previous work with unspecified clay types. It should be noted that slightly higher acid concentrations and somewhat finer particle sizes were used in this series of tests as compared to previous work. EXPERIMENTAL WORK Essentially, alumina extraction proceeded in four steps: 1) grinding, 2) calcining, 3) acid leaching, and 4) precipitating of aluminum sulfate. An initial series of reference tests to determine the optimum temperature of solubility for alumina was run using relatively pure kaolin. Kaolin forming clays are hydrous aluminum silicates of the approximate composition 2H2O A12O3 2SiO and kaolinite is the mineral that predominates in most kaolins. 5 The kaolin was ground to -30 mesh and subsequently calcined at temperatures ranging from 100°C to 700°C. Each sample was calcined for 1 hr in a muffle furnace and in turn subjected to sulfuric-acid leaching (H2SO4, 9 molar) for a 2-hr period. The filtrates were analyzed for the amount of dissolved alumina recovered.637 Also, each sample of leached or barren residue was

Jan 1, 1968

By J. W. Eckerd

Anthracite mining developments have not been as spectacular as the advances made for bituminous coal. The reasons are well known, i.e., steeply pitching seams of the western, eastern, middle and southern fields, and the physical conditions of the strata in which the seams are situated. Beds with moderate pitches (30º to 35º or less) have been mined with coal planers, longwall with movable props, shaker chutes, coal borers and large diameter boring machines. However, the use of this equipment has been limited to a relatively small portion of the production. Long-hole drilling has been developed from a point where holes of 25 or 30 ft have been replaced by those up to 130 ft. This has been possible through the introduction of primacord and similar detonating agents that can fire a long train of explosives with one cap. The usual practice in long-hole mining is to drive a gangway, chutes and monkey heading, or return airway, in the normal development manner. Two breasts can then be driven from the lower to the upper level to act as openings for the beginning of the long-hole work. Following completion of the development, holes can then be drilled from the monkey headings 100 ft or more up the pitch through the coal to within 15 ft or more of the upper level, depending on the nature of the coal on the roof. The thickness of the coal bed determines the spacing of the long holes, although they usually are on 6-ft centers for a 6-ft thick coal seam. The Bureau of Mines has conducted extensive investigations and tests on the development of a hydraulic mining system to be used in conjunction with hydraulic hoisting. Tests were conducted in cooperation with a large anthracite producer in a coal seam from 10 ft 6 in. to 15 ft in thickness and on a pitch from 0º to 20. This particular mining procedure is adaptable only to thick seams on relatively flat pitch as the maneuverability of the hydraulic jumbo is an important restricting factor.

Jan 2, 1968

By J. Ostachowicz, B. Holynska, M. Lankosz

The paper presents an analyzer and the method for the continuous determination of weight percentage of ore grains with diameter smaller than 75 µm in mineral slurries. The method is based upon the measurement of characteristic x-rays of copper excited by primary radiation of two different energies 16.5 keV and 60 keV from Pu238 and Am241 sources respectively. Additionally the backscattered primary radiation is measured in order to correct the variations of the solids content in the slurry. Since the particle size distribution of slurry can be described by the Rosin-Rammler formula, some calculations have been carried out in order to evaluate the influence of distribution parameters upon the results of the measurements of weight percentage U75 of particles smaller than 75 µm. The influence of solids content and of the copper concentration variation on the results has been also evaluated.1 It resulted from the calculations that the ratio rl/rz, where rl and r2 are the relative intensities of copper characteristic x-rays excited with 16.5 keV and 60 keV photons respectively does not depend on the copper content within the range 1 % to 4% of copper and is slightly dependent on the solids weight fraction and its chemical composition. The change of the dispersion parameter of the Rosin- Rammler distribution from 0.5 to 0.9 results in a change of value of U75 of approximately 3.0%. The results of calculations have been confirmed by the results of laboratory experiments. Therefore, a prototype of industrial analyzer for continuous determination of weight percentage of particles smaller than 75 µm has been designed and made. Its schematic drawing is shown in [Fig. 1]. Slurry is flowing down through steel flow-cell of the length equal to approx. 2 m. In the center, two XRF measuring heads (1) and (2) are located. Each of the heads comprises a rigid waterproof cover (3) with the mylar window (4), in which a proportional counter of resolution 15% for 6.4 keV is mounted with a preamplifier (5). The low- energy isotope source (6) is centrally located above the detector

Jan 1, 1980

AT THE beginning of February the British Government announced acceptance of the American terms for funding the war debt, the main features-being as follows: Interest rate of 3 per cent. for the first 10 years and then 3 ½ per cent. up to the final extinguishment of the debt at the end of 62 years. The interest from the time since the loans were made to the actual beginning of the funding arrangement to be recomputed at 4 1/4 per cent. instead of the 5 per cent. rate now in effect. Congress ratified the contract respecting the British debt. The ship subsidy bill was relegated to the rear, which is indeed an end to the project. The natural consequence of this will be a liquidation of the Govern-ment's shipping business. The joint committee on the reorganization of Govern-ment departments made its report to the President. In general this seems to offer a well-considered plan for the coordination of Government service. The pro-posals respecting the bureaus that are particularly associated with the mining industry may be subject to criticism. According to the committee's plan, the Geological Survey remains in the Department of the Interior, but the Bureau of Mines and the compilation of the statistics of mineral production are transferred to the Department of Commerce. The Lausanne conference among the European powers came to an end early in February, without any treaty having been signed, owing to the refusal of the Turks to accept the ultimatum of the Allies. Theoreti-cally this left conditions in a state-of war between the Allies and Turkey. However, no actual movements have resulted. The French and Belgians continued to hold the Ruhr district of Westphalia, extending their lines and administration of the region. The Germans adhered to the policy of passive resistance. In the Parliament of Great Britain the French and Belgian policy was plainly declared to be unwise and dangerous. French and Belgian industries, moreover, were troubled by strikes among their own coal miners for higher wages. The Poles and Lithuanians engaged in border war-fare;. the civil war in Ireland continued. The rest of the world was quiet insofar as military operations are concerned.

Jan 2, 1923

By Amitava Gangulee

A recent investigation has shown that solid solution hardening is almost absent in the quasibinary system SnTe-pbTe.1 The lack of solid solution hardening was attributed to the small difference of only about 3 pct between the atomic sizes of lead and tin, and to the fact that the formation of these solid solutions involved changes only in the sublattice occupied by the lead and tin atoms. The investigation reported here is concerned with the quasibinary system PbSe-PbTe which, similar to the SnTe-PbTe system, forms a continuous series of solid solutions2 and has the same NaC1-type (Bl) structure. The size difference between the selenium and tellurium atoms, however, is slightly larger than 7 pct. No indication of any ordering of the lead and tin atoms at. selected compositions had been found in the system SnTe-PbTe, which had been explained by the weak second-nearest-neighbor interactions between lead and tin atoms.' The possible occurrence of an ordering transition in the system PbSe-PbTe was also investigated in the present work. Polycrystalline specinlens of PbSel-1-xTex (x = 0, 0.20, 0.25, 0.33, 0.50, 0.67, 0.75, 0.80, and 1.0) were prepared by melting appropriate amounts of 99.999 pct pure Pb, Se, and Te j.n evacuated and sealed Vycor capsules. The capsules were quenched in water. The solidified ingots were homogenized at 800°C for 14 days. Chemical analysis of the homogenized ingots showed that the deviations from the stoichiometric compositions were less than 0.1 at. pct for each component. Part of each ingot was ground to pass through a 75 g sieve and pressed into 25.4 mm by 12.7 by 2 mm briquettes. Duplicate sets of specimens, each containing at least one briquette and part of the ingot of each composition, were sealed in evacuated Vycor capsules. Both sets were annealed at 500°C for 7 days; one set was quenced in ice-water and the other was cooled to room temperature over a period of 14 days.

Jan 1, 1970

By C. L. Rabe

The Muddy and Dakota sands, more commonly known as the "D" and "J" sands, respectively, of the Denver-Julesburg Basin are correlative over a large area. It is reasonable to believe, therefore, that depositional environment throughout the Basin was comparable. Local variations in sand development do occur, however, and productivity is often governed by permeability as well as structural position. Experience indicates permeability is commonly a function of cementing material. While cases of siliceous or calcareous cementing have been observed, the bonding material is, for the most part, clay. Under the latter circumstance, clay should bear some relation to permeability. Similarly, gamma radiation should bear some relation to the amount of clay. This study was undertaken to determine if a cross relation exists between gamma radiation and permeability. RESULTS OF INVESTIGATION A qualitative relation does exist between gamma radiation and permeability for clay-bonded Muddy and Dakota sands of the Denver-Julesburg Basin. This is illustrated graphically by Fig. 1, which shows corrected gamma ray deflection vs permeability for five wells over an area approximately 50 miles long and 8 miles wide. The "corrected" gamma ray deflection cannot be read directly from the gamma ray survey in all cases. It became apparent early in the investigation that methods would have to be developed for converting all gamma ray surveys to a common deflection scale and to correct for thin bed effects. COMMON SCALE DEFLECTION Because all logs are not recorded in the same calibration units or at the same sensitivity, it was felt they could be most readily converted to a common scale by measurement of deflection in inches from zero. Initially, four wells in the Jacinto field of Nebraska were carefully correlated, and selected intervals were planimetered to obtain average deflections. Average deflections of planimetered intervals from three of the wells were plotted vs those of the fourth well which was to be used as a common reference. The plots are shown in Fig. 2. While results obtained by this method in the Jacinto field were relatively good, the planimetered intervals were not easily correlated with logs from other fields. Furthermore, the planimetric method is laborious and not readily adapted to routine operations. Deflection of the "Bentonite marker" was found to

Jan 1, 1958

By William Newnam

THE smelting of galena in the ore hearth has been practiced in many countries for several hundred years with varying success. In the United States the water-jacketed American hearths and the Jumbo hearths have found some favor, in the Missouri lead belt, where large quantities of non-argentiferous galena concentrates are produced. In form and method of operation the ore hearth has changed but little since its earliest conception. A detailed description of the furnace is not needed here; it has been fully described in most works on the metallurgy of lead and in many technical papers. Since its field is restricted to non-argentiferous galena, containing over 68 per cent. of lead, its .use is limited to a few districts; and, on account of certain disadvantages attending its operation, modern sintering and blast-furnace practice has nearly driven it out of the Missouri field. It is not generally known that the cost of producing pig lead is smaller by the hearth method than by sintering and blast-furnace smelting. Yet it is doubtful if any metallurgist knowing this to be true would recommend an American hearth installation-by reason of the disadvantages which will be briefly enumerated. The furnace has been limited to a length of from 4 to 5 ft., requiring for its operation two men working an 8-hr. shift as a maximum. The product per man is small; the work is hot and laborious; and the difficulty of completely removing the dust and fume has made it a notorious source of lead poisoning. Although suitable, for, operations on a small scale a large number of hearths would be required for a plant smelting 10,000 tons of 68 to 70 per cent. concentrates per month; and the number of semi-skilled laborers would be six times the number of hearths-a condition which is prohibitive. On account of the high percentage of dust and fume produced, a large flue and bag-house installation is required and, in the past, the handling and re-treatment of. this dust and fume has been a serious problem.

Jan 10, 1915