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By Herbert Hoover

BOTH the directors of industry and your leaders have made great progress toward a new and common . ground in economic conceptions, which, I am confident, has had a profound effect upon our economic progress during the last few years. That is the conception that industry must be constantly renovated by scientific research and invention; that labor welcomes those labor-saving devices; that labor gives its full and unrestricted effort to reduce costs by the use of these machines and methods; that the savings from these reduced costs shall be shared among labor, employer and the consumer.

Jan 1, 1930

By C. P. Lawhon, J. P. Simpson, W. M. Evans

Recent efforts to design drilling fluids for increased drifting rates have confirmed some laboratory results of other investigators, but have also produced additional data that should be considered. These data were obtained under controlled test conditions using a microbit drilling machine. Clays and some polymers have previously been reported to cause reduction in drilling rate. Recent data have shown that under laboratory conditions, suspensions of a single day or polymer have sometimes given faster drilling rates than when water was used. Measurements have been made of clay suspensions and polymer suspensions comparing filtration (I) under API conditions, (2) while drilling with temperature of 150F and differential pressure of 1,000 psi and (3) under dynamic conditions after drilling. Some correlation between instanraneous filtration (white drilling) and drilling rate has been observed. INTRODUCTION Several papers have been presented that related drilling fluids to penetration rate. Generally, it was found that a decrease in the solids concentration resulted in significant increases in the drilling rate. Of course, this change also resulted in a decrease in the viscosity of the drilling fluid.' Conclusions from investigations by this laboratory are in agreement. Data have shown that of the simple mud measurements commonly made at the drilling rig (density, plastic viscosity. yield point, API filtrate and total solids), only the density and total solids have a significant relationship to the drilling rate in Berea sandstone when attempting to correlate a single mud property individually.' More recent drilling rate experiments have been designed to study (1) effects of individual clays and polymers on drilling rates in Berea sandstone and Lueders limestone, (2) the relationship between drilling rate and dynamic filtration as measured after drilling and (3) the relationship between drilling rate and dynamic filtration as measured during drilling. Data show that drilling rates are dependent upon type and concentration of particles, type of formation and filtration of the individual fluids while drilling. Mud pressure: pressure of drilling fluid as measured after leaving the drilling chamber (Fig. 1). This is taken to be approximately the mud pressure just past the bit and at the face of the formation. Terrastatic pressure: pressure representing weight of overburden. Formation pressure: pressure of formation fluid as measured at outlet of drilling chamber (Fig. 1). This is taken to be approximately the pressure of fluid in the interstices of the formation. Differential pressure: difference between the mud pressure and formation pressure. LABORATORY EQUIPMENT AND TESTING PROCEDURE The drilling equipment was described in two previous publications."' Main components are a drilling chamber, filter-heater, rotary drive and variable-speed circulating pump. Auxiliary pumps supply pressure boosts for the mud, terrastatic and formation pressures. All equipment is designed for 15,000 psi and 500F. Capacity of the circulating system is approximately 7 gal. The mechanical design was facilitated by moving the rock down onto the bit. Data collected with this design should not differ from that obtained by a normal design where the bit moves into the rock. Drilling fluid is pumped through 50 ft of ID pipe coiled in an oil bath, enters the rotary shaft at a right angle and is pumped through the jets on the bit (Fig. 1). Most of the drilled solids are extracted by a screen mounted in the circulating system on the suction side of the pump. Data reported in this paper were obtained by controlling these parameters: mud pressure, 5,000 psi; formation pressure, 4,000 psi; terrastatic pressure, 5,000 psi; force on bit, 1,000 Ib; formation, Berea sandstone and Lueders limestone; flow rate, 7 gal/rnin; bit, 11/4-in. diameter with two 0.078-in jets; mud temperature. 150F; and rotary speed, 60 rpm. Mud pressure was controlled at 5,000 psi, thus giving a differential pressure of 1,000 psi even though the fluid densities varied. Cores of 3%;-in. diameter and 8 in. long were selected from quarry blocks to provide some control of grain size distribution, permeability and porosity. A 2-in. section was cut off each core and a I -in. diameter plug was taken from this section. Permeability to 5 percent by weight sodium chloride solution was determined and the large cores were

By W. C. Knoblaugh

Rotary kilns are adaptable to many fuels, but this paper deals principally with the use of powdered coal. The observations and conclusions presented are based on rotary kilns used in the manufacture of basic refractories for steel furnaces. Solid fuels are pulverized for two principal reasons: (I) ease of control, and (2) rapidity of combustion. By the use of pulverized coal, the operator can increase or decrease the fuel supply by small increments and with very little time lag between the change of control and the resultant change in the flame. This is extremely important in this type of furnace, as the temperature range for maturing the clinker is very narrow. By fine grinding, it is possible to increase the rate of burning of the coal, thereby liberating great quantities of heat within a small space in a short time. Under given conditions, temperature is a measure of the heat liberated per unit of time. To attain the temperatures of 2950° to 3150ºF., which are encountered in the manufacture of various steel-furnace refractories, it is estimated that it is necessary to liberate 125,000 to 175,000 B.t.u. per cubic foot of the burning zone per hour. The manufacture of dolomitic refractories is a ceramic process and, as is true in most such processes, the material must be subjected to a certain critical temperature for a certain length of time in order to complete the reaction. If the time of reaction is reduced, the temperature must be increased; in other words, if the rate at which the material flows through the hot zone of the kiln is increased, the temperature of the hot zone must be increased to compensate for this shorter exposure to the flame. Firing with Pulverized Coal Fig. I is a line drawing of a rotary kiln with the attendant equipment indicated in their relative positions. The kiln proper consists of a sloping, refractory-lined steel tube rotating slowly about its longitudinal axis (0.75 r.p.m.), and is countercurrent in operation in that the raw feed is introduced at the stack end and gradually approaches the zone of highest temperature at the lower end, where the fuel is introduced. Before 1930, the usual method of firing a rotary kiln was to store the coal in the pulverized form and then feed from this storage to the kiln as needed. This proved unsatisfactory and dangerous because of dust explosions and the inability to obtain an even feed to the kiln caused by arching of the coal in storage and flooding of the coal feeders. In later years the practice has been to store the raw coal and grind it as it is needed. Such a layout is indicated in Fig. I. The coal is stored in bins, charged from the top and drawn from the bottom into recording scales and then into some type of unit pulverizer. There are a number of good pulverizers .on the market, each incorporating features that the manufacturer considers outstanding.

Jan 1, 1948

By W. C. Knoblaugh

Rotary kilns are adaptable to many fuels, but this paper deals principally with the use of powdered coal. The observations and conclusions presented are based on rotary kilns used in the manufacture of basic refractories for steel furnaces. Solid fuels are pulverized for two principal reasons: (I) ease of control, and (2) rapidity of combustion. By the use of pulverized coal, the operator can increase or decrease the fuel supply by small increments and with very little time lag between the change of control and the resultant change in the flame. This is extremely important in this type of furnace, as the temperature range for maturing the clinker is very narrow. By fine grinding, it is possible to increase the rate of burning of the coal, thereby liberating great quantities of heat within a small space in a short time. Under given conditions, temperature is a measure of the heat liberated per unit of time. To attain the temperatures of 2950° to 3150ºF., which are encountered in the manufacture of various steel-furnace refractories, it is estimated that it is necessary to liberate 125,000 to 175,000 B.t.u. per cubic foot of the burning zone per hour. The manufacture of dolomitic refractories is a ceramic process and, as is true in most such processes, the material must be subjected to a certain critical temperature for a certain length of time in order to complete the reaction. If the time of reaction is reduced, the temperature must be increased; in other words, if the rate at which the material flows through the hot zone of the kiln is increased, the temperature of the hot zone must be increased to compensate for this shorter exposure to the flame. Firing with Pulverized Coal Fig. I is a line drawing of a rotary kiln with the attendant equipment indicated in their relative positions. The kiln proper consists of a sloping, refractory-lined steel tube rotating slowly about its longitudinal axis (0.75 r.p.m.), and is countercurrent in operation in that the raw feed is introduced at the stack end and gradually approaches the zone of highest temperature at the lower end, where the fuel is introduced. Before 1930, the usual method of firing a rotary kiln was to store the coal in the pulverized form and then feed from this storage to the kiln as needed. This proved unsatisfactory and dangerous because of dust explosions and the inability to obtain an even feed to the kiln caused by arching of the coal in storage and flooding of the coal feeders. In later years the practice has been to store the raw coal and grind it as it is needed. Such a layout is indicated in Fig. I. The coal is stored in bins, charged from the top and drawn from the bottom into recording scales and then into some type of unit pulverizer. There are a number of good pulverizers .on the market, each incorporating features that the manufacturer considers outstanding.

Jan 1, 1948

Noranda Mines, of Quebec, signed a contract for construction of a $20 million copper refinery at Gaspe, P.Q. The plant is expected to have a 65500-ton daily capacity for both concentrator and smelter. Extensive drilling. around Gaspe has revealed more than 65 million tons of 1 to 2 pct copper in several deposits. Cerro de Pasco Corp. has called a special stockholders meeting for August 19 to obtain permission to engage in the oil and natural. gas business, in addition to its present production of zinc, lead, copper, silver and other metals. St. Joseph Lead Co. recently entered the oil development field. The United States, Canada and Great Britain have agreed to establish a permanent organization to work on unification of engineering standards. General accord has been reached on drafting standards and practices, screw threads, fittings for gas cylinders, and fits and tolerances. Permanent committees will study these fields. Reconstruction Finance Corn approved the largest sum in its history. for a mining enterprise when it loaned $94 million to San Manuel Copper. Corp., of Pinal County, Ariz. The loan will be used to increase production of copper and molybdenum, in what was described as-the biggest copper deposits in the country. Three large gold mining concerns operating in the Philippines told the Philippine Wage Board that they would be forced to close if they had to boost miners' wages 500 to $2 per day. The companies are Mindanao Mother Lodes, Benguet Consolidated, and Balatoc Mining Co.

Jan 1, 1952

By Albert Hahn

ABOUT three years ago John Hays Hammond took over the control of the Eureka Metallurgical Co., at Salt Lake City, Utah. Funds were advanced for investigating the process invented by R. V. Smith, for concentrating oxidized lead ores. A great deal of laboratory work was done and a reagent was developed by C. M. Nokes of Salt Lake, which was found to be particularly suitable for oxidized copper ores, refractory manganese silver ores, and oxidized gold ores. After sufficient laboratory work had been performed to demonstrate the fundamental principles of these inventions, a test mill, having a capacity, of 20 tons of ore daily, was erected at Murray, Utah. In this test mill approximately 1200 tons of various types of ores have been concentrated by means of the above-mentioned process and reagents, and this large-scale work as well as laboratory work is being continued at present. Details of these mill tests are given in Table 1, and a representative group of laboratory tests are shown in Table 2. The process requires no special machinery or appara-tus. Its success depends entirely, on the method of preparing the pulp and its subsequent flotation in clean water, as outlined in the Smith patent. The reasons for the success of the Nokes special reagent are not definitely known. The outstanding feature, which seems to be of extreme importance, is that when the concentrates are examined under the microscope, each particle of mineral appears to have a particle of paraffin, attached to it. This paraffin-mineral combination seems to be particularly suitable for flotation and it follows that any coating oils readily attach themselves to the paraffin-mineral combination.

Jan 9, 1923

By William L. Fink, H. R. Freche

This is the thirteenth paper of a series from the laboratories of the Aluminurrl Company of America presenting the results of investigations of equilibrium relations in aluminum-base alloys prepared from electro-lytically refined aluminum. The ninth paper, on The Constitution of High-purity Aluminum-titanium Alloys,' presented a type of system that had not previously been encountered in aluminum alloys. Subsequent work has shown that there are several similar binary aluminum diagrams including that of aluminum and chromium. The present investigation was limited to the cxtreme alnminum end of the aluminum-chromium system. The first systematic investigation of the aluminum-chromium equilibrium diagram was carried out by Hindrichs.? The resulting equilibrium diagram with some imaginary additions suggested by Guillet3 is shown in Fig. 1. Recently Goto and D6gane4 investigated the constitution of aluminum alloys containing up to 32 per cent chromium, and presented the diagram that is reproduced in Fig. 2. Wide discrepancies in the two diagrams are evident. The following intermetallic compounds have been reported in the literature: A1Crl5,6 AlloCrlzSi,5 AlCr4,6 AlCr3,7 AlaCr.8 Preparation of Alloys and Chemical Analyses With the exception of sample Y4206, which will be described under Determination of Hyperperitectic Liquidus, the alloys were prepared from electrolytically refined alurninum% Of which the analysis is given in

Jan 1, 1933

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Jan 1, 1938

Discussion Of the paper Of GEORGE K. BURGESS, J. J. CROWE, H. S. RAWDON, and R. G. WALTENBERG, presented at the Pittsburgh meeting, October, 1914, and printed in Bulletin NO. 93, September, 1914, pp. 2433 to 2437. ALBERT SAUVEUR, Cambridge, Mass.-The Bureau of Standards has once more rendered a public service. Manufacturers and consumers of steel rails alike should welcome the important results now laid before them by Dr. Burgess and his co-workers. Personally I welcome these results all the more that in the past, as some of the members may remember, I have never failed, when occasion arose, to call the attention of rail manufacturers to the importance of controlling the finishing temperature of their rails. The pioneer metallographic work conducted at the South Works of the Illinois Steel Co. in the early '90s clearly brought out the close relations existing between the manufacture, properties, and finishing temperature of steel rails and I think I may say without fear of being contradicted that the results of this early investigation had considerable influence in drawing the attention of manufacturers to the importance of finishing temperature and of heat treatment in general. The results now before us should be, it seems to me, of great value to rail manufacturers in their efforts to produce a better and, above all, a safer rail. It seems to be demonstrated in this paper that there is no difficulty in installing in rail mills pyrometric outfits, making it possible to record, without interfering in the mill operations, the temperature of the rails as they leave the finishing rolls, or of the ingots as they are withdrawn from the soaking pits, or at any intermediate point in the process of manufacture. The inference necessarily follows that manufacturers should see to it that such pyrometric installations are made, in order that they may actually know, instead of guessing at, the temperature of their rails;, and, for obvious reasons, rail consumers should insist upon such installations. In the rolling of heavy sections especially should care be taken to lower their finishing temperature, seeing that the present tendency is to finish them at higher temperature, whereas, owing to the slower cooling of their central portions, which makes for coarseness of grain, they should, if anything, be finished at a lower temperature than lighter rails.

Jan 4, 1915

By H. C. Vacher

THE limiting concentrations of carbon and oxygen which may co-exist at equilibrium in liquid iron are important in determining the degree to which liquid steel may be refined before it is deoxidized. Most refining processes depend upon the oxidation of a highly carburized iron which invariably results in contaminating the steel with oxygen. The oxygen .thus introduced presents many problems to the refiner, who in turn has attempted to rid the steel of this impurity by deoxidation with elements such as manganese, silicon and aluminum. The importance of the limiting concentrations of carbon and oxygen is accentuated in view of a number of recent researches which have indicated in many instances the existence of relations between oxide inclusions and dissolved oxygen and physical properties and chemical behavior of steel. The determination of the equilibrium concentrations of carbon and oxygen existing in iron under steelmaking conditions is obviously of fundamental importance. It has been generally assumed that the product of the equilibrium concentrations of carbon and oxygen in liquid iron is a constant and that this product is directly proportional to the carbon monoxide pressure in equilibrium with the liquid iron. Herty1,2 has computed values for this product based on open-hearth data which are all in the neighborhood of 0.01 to 0.03 (per cent. FeO X per cent. C) for temperatures in the vicinity of 1550° to 1600 C. and one atmosphere pressure. Kinzel and Egan3 have attempted to determine the value of this product by exposing liquid iron to carbon monoxide at one atmosphere pressure. The value reported by them was 0.0005 at 1550°. C. In. order to apply certain equations to the rate of carbon elimination in the open-hearth process, Feild4 found it necessary to assume. a value of 0.0102 at 1580° C. for this

Jan 1, 1931

By D. I. Cameron

A graphical method has been developed and tested for separating the effects of grain boundary and lattice diffusion in polycrystalline materials. The method is based on the assumptions that for unidirectional diffusion from a plane source of radioactive material, the penetration of activity far into the specimen from the source is due solely to grain-boundary effects, and 2) pure grain-boundary penetration is described by a linear plot of log activity vs the perpendicular distance x from the source. The former is based on the fact that at any temperature the grain-boundary diffusion coefficient is always very large relative to the lattice diffusion coefficient; and the latter is based on the derivation of Fisher.1 Using these criteria along with appropriate penetration data (in this case, data for the diffusion of Cb95 in pressed and sintered UO2) one first plots the data as log activity vs x2 and as log activity vs x, as shown by curves 1 and 2, respectively, in Fig. 1. A tangent line to curve 2 for large x (curve 3) is then transferred to the x2 plot as curve 4. The subtraction of curve 4 from curve 1 yields curve 5 which represents only lattice diffusion and may therefore be related to the diffusion coefficient by using the appropriate solution to Fick's second law. It should be noted that the method has inherent inaccuracies for small and large values of x2 and only the subtraction at intermediate values can be used. For the illustrated specimen the calculated diffusion coefficient is 3.4 X 10-11 sq cm per sec at 1445°C while data using a single crystal of UO2 at the same temperature yielded a value of 2.9 x 10-11 sq cm per sec.2 The same method of subtracting grain-boundary diffusion effects to obtain lattice diffusion coefficients has been successfully used to determine self-diffusion coefficients of Th230 in polycrystal- line thoria.

Jan 1, 1962

By R. H. Schnitzel

Internal-friction peaks have been observed in tungsten single crystals at about 300° and 400°C. The characteristics of these peaks are similar to interstitial peaks observed in other bee metals; therefore, the origin of these peaks appears to he the Snoek mechanism. The interstitial responsible for the peak at about 300°C has not been identified. Carburizing increases the magnitude of the peak at about 400°C; consequently, it appears reasonable to suppose that the specific interstitial associated with this peak is carbon. The activation energies associated with the 300° and 400°Cpeaks are about 35,000 and 45,000 cal per mole, respectively. INTERNAL - friction peaks resulting from the stress-induced diffusion of interstitials (Snoek relaxation peaks) have been frequently observed in bee metals.1-5 Attempts to detect Snoek relaxation peaks in tungsten have, however, not been fruitful.' Failure to find Snoek peaks in sintered tungsten can perhaps be attributed to one or more of the following difficulties: a) the relatively low purity of the sintered tungsten; b) the lack of extensive metallurgical knowledge about tungsten-interstitial alloys, such as suitable interstitial dosing and quenching procedures; and c) the inconsistency of some of the interstitial analyses of tungsten, which reflects itself in one's inability to be sure of the nature of the specimens. This present investigation did not overcome all of these difficulties for successful tungsten internal-friction measurements. Some of these difficulties still persist and new difficulties were encountered during the course of this investigation. Nevertheless, the use of electron-beam tungsten single crystals having somewhat greater purity levels than sintered tungsten combined with appropriate carburizing and quenching procedures permitted a reasonable attempt to be made. As a consequence, internal-friction peaks were observed in these tungsten single crystals at about 300° and 400°C. These peaks were found to be unstable, since they annealed rapidly away during a sequence of internal-friction measurements. Hence, it was necessary to construct an apparatus having a faster heating rate to study some of the details of these peaks. From the behavior of these peaks as well as our knowledge of similar peaks in other bee metals, one can reasonably conclude that these peaks are caused by residual interstitial impurities within these crystals. Further investigation of these peaks after the application of various metallurgical treatments lent credence to this supposition. EXPERIMENTAL TECHNIQUE The internal friction of tungsten single crystals was measured using two different pieces of apparatus both of which are of essentially the same conventional design, namely the KE type of torsion pendulum. The important difference between these two types of apparatus was in the attainable heating rate and method of protection of the specimen from atmospheric contamination. The apparatus designated "number 1" was enclosed in a vacuum chamber which was heated by an externally mounted furnace. It had a slow rate of heating which was estimated to be about 4°C per min from room temperature to about 350°C and then about 1°C per min to 600°C. The internal friction of tantalum was measured with this apparatus and the established Snoek peaks were found.' These tantalum peaks in the temperature range from room temperature to 400° C served as a check for the apparatus. The apparatus designated "number 2" having a faster heating rate than number 1 was not elaborate. It consisted of a mounted nickel tube to which split heating elements were attached. Argon was used as the protective atmosphere. The measured heating rate was about 12° to 15°C per min whereas the cooling rate was somewhat slower at about 10° C per min because of the increased difficulty encountered in stabilizing the temperature. No surface oxidation of the specimen was noted after any test. This apparatus was also checked with the known peaks of tantalum.1 The preparation of the single-crystal specimens for internal-friction measurements consisted of centerless grinding the crystals from an approximate 0.200 in. diameter to 0.030 to 0.040 in. in diameter, and then electropolishing them to about 0.020 in. in diameter. Single crystals processed in this manner are designated as being in the virgin condition. Since the length of crystal varied from 3 to 9 in., the test frequency varied from about 1 to 2 cps. The frequencies of measurement, axial orientations, and chemical analyses for the various crystals are listed in Table I. The controlled addition of carbon into tungsten is a difficult problem. Attempts to find the critical conditions necessary for an equilibrium treatment were not fruitful. Therefore, a simple nonequi-librium method was used. The addition of carbon to these crystals consisted of appropriately combining three treatments—carburizing to achieve a case, annealing to partially dissolve the carbon into the

Jan 1, 1965

By M. Kaufman, A. E. Palty

THE mechanical properties of an alloy under given test conditions are in the main determined by the grain size and the phases present, their distribution and temperature-time dependence. Alloys intended for use at elevated temperatures, especially multiphase alloys depending upon precipitation reactions for strengthening, are particularly susceptible to changes in the phases present. Unfortunately, for modern superalloys, very little published information exists which relates the mechanical properties to the basic structural variables. The present work is an effort to do this for an alloy widely used in aircraft gas turbines and related applications, Udimet 500.* The mechanical properties inves- two heats is within the normal specifications for the alloy. However, the elements which most strongly influence the phase reactions, C, Ti, Al, and Mo, are comparable in the two heats. There was no intentional addition of boron, but normal pickup is about 0.002 pct. The vacuum-melted material was received in the form of centerless ground wrought bar stock % in. diam. PHASE STUDIES A) Methods—Two methods were used to determine the phases present: X-ray diffraction measurements on electrolytically digested residues, and microscopic examination. No single commonly used electrolyte will reveal all the phases that may be present; therefore, two complementary acids were selected: HCl and H3PO4. The necessity for this will be shown below in the results. The acid concentrations used were 10 pct HC1 in alcohol and 10 pct H3 PO4 in water. The current density was maintained below 0.1 amp per sq in. Residues were rinsed and separated by centrifuga-tion. X-ray diffraction patterns were obtained in a 114 mm Debye-Scherrer type camera using cobalt radiation. A temperature of 2250°F was selected to obtain as complete solutioning of phases as possible without encountering incipient melting. Specimens were

Jan 1, 1961

Correspondent. Must be able, by virtue of, connection, to forward; daily ands weekly, reports, outlining, conditions affecting economics of. industries, particularly the metallurgical, and chemical, industries. New. York, City. R-1982. Sales Lubrication. Engineer. Preferably with experience, as chief marines engineer familiar with internal-combustion; engines and, with, automobile trade. Must be good salesman, of goody appearance and be able to meet people. Middle West. Salary $27.00: to start. R71984.

Jan 12, 1919

By W. C. Knoblaugh

ROTARY kilns are adaptable to many fuels, but this paper deals principally with the use of powdered coal. The observations and conclusions presented are based on rotary kilns used in the manufacture of basic refractories for steel furnaces. Solid fuels are pulverized for two principal reasons: (I) ease of control, and (2) rapidity of combustion. By the use of pulverized coal, the operator can increase or decrease the fuel supply by small increments and with very little time lag between the change of control and the resultant change in the flame. This is extremely important in this type of furnace, as the temperature range for maturing the clinker is very narrow. By fine grinding, it is possible to increase the rate of burning of the coal, thereby liberating great quantities of heat within a small space in a short time. Under given conditions, temperature is a measure of the heat liberated per unit of time. To attain the temperatures of 2950° to 3150°F., which are encountered in the manufacture of various steel-furnace refractories, it is estimated that it is necessary to liberate 125,000 to I75,000 B.t.u. per cubic foot of the burning zone per hour. The manufacture of dolomitic refractories is a ceramic process and, as is true in most such processes, the material must be subjected to a certain critical temperature for a certain length of time in order to complete the reaction. If the time of reaction is reduced, the temperature must be increased; in other words, if the rate at which the material flows through the hot zone of the kiln is increased, the temperature of the hot zone must be increased to compensate for this shorter exposure to the flame. FIRING WITH PULVERIZED COAL Fig. I is a line drawing of a rotary kiln with the attendant equipment indicated in their relative positions. The kiln proper consists of a sloping, refractory-lined steel tube rotating slowly about its longitudinal axis (0.75 r.p.m.), and is countercurrent in operation in that the raw feed is introduced at the stack end and gradually approaches the zone of highest temperature at the lower end, where the fuel is introduced. Before 1930, the usual method of firing a rotary kiln was to store the coal in the pulverized form and then feed from this storage to the kiln as needed. This proved unsatisfactory and dangerous because of dust explosions and the inability to obtain an even feed to the kiln caused by arching of the coal in storage and flooding of the coal feeders. In later years the practice has been to store the raw coal and grind it as it is needed. Such a layout is indicated in Fig. I. The coal is stored in bins, charged from the top and drawn from the bottom into recording scales and then into some type of unit pulverizer. There are a number of good pulverizers on the market, each incorporating features that the manufacturer considers outstanding.

Jan 1, 1946

By A. M. Gaudin, D. W. Fuerstenau

By streaming potential techniques, the zeta potential of quartz has been measured as a function of the concentration of dodecylammonium salts at different pH values. These experiments indicate that adsorption of dodecylammonium ions takes place as individual aminium ions until a certain critical concentration is reached in the double layer, at which point the adsorbed collector ions begin to associate into patches of ions, called hemimicelles. Because of its effect on the surface potential of quartz, pH controls the adsorption of dodecylummonium ions. The value of cooperating agents and nonionized constituents of flotation systems is discussed. Previous investigation of the role of pH in the flotation of quartz with anionic collectors is here extended to an inquiry of how the cationic collector, dodecylammonium acetate, is adsorbed at the quartz-solution interface. The equilibrium amount of this collector adsorbed by quartz has already been measured as a function of concentration and pH. The weight of prior evidence has suggested that two mechanisms are involved in the adsorption of this collector by quartz, but with existing adsorption measurements alone it is not

Oct 1, 1955

By Charles H. Behre

KEYNOTE of the mining geology sessions was the preparation for an extensive war with all that this implies as to the need for strategic minerals, both metallic and nonmetallic. Nevertheless the sessions also included many papers of less urgent, more theoretical interest. The stress of wartime production had the effect of giving an unusually full and rich program, the longest in recent years, with sessions continuing virtually throughout the meeting. Some papers dealt with geophysical prospecting as applied to mining geology; others were concerned with the grand strategy of mineral reserves and thus involved the industrial minerals; such "borderline" subjects were presented before sessions held jointly with the Geophysics Committee or the Industrial Minerals Division.

Jan 1, 1942

By F. C. Farnham

In this paper it is shown that the vertical component of the earth's magnetic field for the area of the United States can be very closely approximated by assuming it to be the sum of the vertical components of two magnetic fields. The first of these is the field of the centered dipole described by J. Bartels,l the axis of this dipole intersecting the earth's surface at two antipodal points, the one in the Northern Hemisphere being at latitude 78.5°N. and longitude 69°W., and the dipole having such strength that the vertical component of its field at its axis pole is 0.63 oersted. The second field is that due to a second dipole situated halfway between the center of the earth and a point on the earth's surface at latitude 38.5°N., longitude 91.5°W., the axis of this dipole being along this radius, the south pole being toward the surface, and the dipole being of such strength that its field at the point on the surface mentioned above is 0.069 oersted. Using the field computed on this basis, tables of latitude and longitude correction factors were computed and are included in the paper. It is also shown that the secular variation in the earth's magnetic field may be roughly accounted for by assuming it to be due to motion of the second dipole described above. Although there is an error in the equation used for computing the strength of the field due to the second dipole, the distribution of the field computed is very nearly that of the assumed arrangement of dipoles. Subsequent work by the author reveals that minor changes can be made in the location of the second dipole, which will make the computed field fit the observed field even more closely. It has also been found2 that the vertical component of the field may be represented equally well by a purely empiric relationship.

Jan 1, 1940

By F. C. Farnham

In this paper it is shown that the vertical component of the earth's magnetic field for the area of the United States can be very closely approximated by assuming it to be the sum of the vertical components of two magnetic fields. The first of these is the field of the centered dipole described by J. Bartels,l the axis of this dipole intersecting the earth's surface at two antipodal points, the one in the Northern Hemisphere being at latitude 78.5°N. and longitude 69°W., and the dipole having such strength that the vertical component of its field at its axis pole is 0.63 oersted. The second field is that due to a second dipole situated halfway between the center of the earth and a point on the earth's surface at latitude 38.5°N., longitude 91.5°W., the axis of this dipole being along this radius, the south pole being toward the surface, and the dipole being of such strength that its field at the point on the surface mentioned above is 0.069 oersted. Using the field computed on this basis, tables of latitude and longitude correction factors were computed and are included in the paper. It is also shown that the secular variation in the earth's magnetic field may be roughly accounted for by assuming it to be due to motion of the second dipole described above. Although there is an error in the equation used for computing the strength of the field due to the second dipole, the distribution of the field computed is very nearly that of the assumed arrangement of dipoles. Subsequent work by the author reveals that minor changes can be made in the location of the second dipole, which will make the computed field fit the observed field even more closely. It has also been found2 that the vertical component of the field may be represented equally well by a purely empiric relationship.

Jan 1, 1940

By C. F. Park

Hog Mountain is in the north central part of Tallapoosa County, Alabama, about 13 miles northeast from Alexander City. The Hog Mountain Mining and Milling Co. controls 1658 acres of land and is the only company operating in the district. The principal mine workings are in sections 10 and 15, T.24N., R.22E. The region has been visited by geologists many times, has been briefly described in several papers,' and mentioned in many others. No detailed map of the mine or vicinity has been published. The field work for this report was started in March, 1934, as part of the Public Works reemployment program. About a month and a half was spent mapping both the surface and underground geology. The mine owners and operators have cooperated in every way possible to facilitate the work. N. 0. Johnson, the mine engineer, E. W. Ellsworth, J. E. McCoy and J. G. Englebert have acted as assistants for part of the work. The University of Alabama and the State Geologist's office have aided materially by permitting free use of their libraries and laboratory equipment. Geography Hog Mountain forms a conspicuous ridge that rises to a height of a little more than 1000 ft. above sea level, and about 400 to 500 ft. above the adjacent country. The ridge is composed of granitoid intrusive rock and silicified schist that are more resistant to erosion than the surrounding softer schist. The topography of the area around the ridge is gently rolling and is typical of the subdued forms of the deeply eroded Southern

Jan 1, 1935