Search Documents

By P. R. Hines

Diphenyl guanidine is used as an accelerator in vulcanizing rubber. Other rubber accelerators are also flotation collectors, e.g., dithiocarbamate, thiazole, and the xanthates. Urea and its derivatives are good flotation collectors,' and guanidine is the nitrogen analog of urea. These two characteristics suggested testing diphenyl guanidine as a flotation collector. Diphenyl guanidine has been tried in flotation work previously, but references give no details.'.' Bunker Hill Co. of Kellogg, Idaho, supplied the ore sample used in these tests. The sample was typical of the ore milled in 1949 and contained 4.52 pct Pb and 1.08 pct Zn. A flotation test made by the author with potassium ethyl xanthate as a collector, the same flotation reagents, and the same grind employed in regular Bunker Hill mill practice was the standard for comparing results with the compounds and derivatives of guanidine. The compounds and derivatives of guanidine are only fair collectors of galena. However, if potassium ethyl xanthate were used in the galena float, its presence later in the sphalerite float would make it impossible to introduce another type of collector and be certain which collector contributed the result, so the compound or derivative of guanidine under test was used in both the galena and sphalerite floats in Table I. On both the galena and the sphalerite in the Bunker Hill ore, the depressing action of sodium cyanide and zinc sulfate is much greater with collectors of the guanidine type than with the xanthates. If the depressing agents are left out when a guanidine type of collector is used, but a pH of 8.6 is maintained with either lime or sodium carbonate, the depressing action is approximately the same as in the standard xanthate test. Consequently the depressing agents, sodium cyanide and zinc, were not used in the galena floats of tests 1226, 1228, and 1286, Table I, so the galena floats would be on a comparable basis with the standard xanthate test. As shown by the tests in Table I, the loss in the tail when diphenyl guanidine is used is 8.3 to 9.3 pct, as compared to 17.6 pct with potassium ethyl xanthate, or a recovery of 2.3 to 2.0 lb more zinc. Concentrate grade is 13.7 pct with potassium ethyl xanthate and increases to 22.9 and 31.8 pct with diphenyl guanidine, showing a much higher selectivity. Unless the Barrett's No. 4 coal tar creosote is considered to be a collector, no collector other than diphenyl guanidine is present in the tests, Nos. 1226, 1228, and 1286. Tests 1218, 1253, and 1263 in Table I1 were run to check the effect of the depressing agents used in flotation of the galena (sodium cyanide and zinc sulfate) upon subsequent flotation of sphalerite by diphenyl guanidine. Urea was substituted for potassium ethyl xanthate in tests 1253 and 1263 because it is a good collector for galena and a poor one for sphalerite, and the effect of the depressing agents is more marked with urea than with potassium ethyl xanthate. Test 1205 checks the effect of urea alone without any depressing agents when used for the flotation of galena. Table I1 shows that diphenyl guanidine as a collector for sphalerite is compatible with other flotation reagents used in floating galena. When the depressing agents sodium cyanide and zinc sulfate are used in the galena flotation step, the amount of lime in the sphalerite flotation must be increased (compare 1253 and 1263). Table I11 gives some of the compounds of guanidine which were tested and compared. Some of the compounds and derivatives of guanidine* are solu- * Diphenyl guanidine is in commercial production and is available on the market. ble in water and others are not. Those tested were fed dry. When an organic collector is promising, its compounds and derivatives should be tested and their comparative collecting power recorded. Eventually, in this way, it may be possible to discover some of the essential chemical characteristics of a good collector. For example, it is interesting to compare the diphenyl and dibutyl derivatives in Table IV with those of urea in Table 111, Example 3, U. S. Patent 2,664,198. All are good collectors. Table I shows some of the effects of lime on recovery of sphalerite by diphenyl guanidine. Table V

Jan 1, 1960

By P. E. Busby, C. Wells, M. E. Warga

Fundamental data on the rate of diffusion of boron in austenite and solubility of boron in the a and y phases of iron and steel have been obtained from deboronizing experiments and provide partial explanations for some of the phenomena observed in boron steels. The rate of diffusion of boron is about the same as carbon in austenite. The solubility of boron in austenite at normal heat-treating temperatures is less than 0.001 pct. A partial tentative Fe-B phase diagram in the important low boron concentration ranges and an equation representing the diffusion of boron in austenite are presented. A LTHOUGH a search of the literature revealed ALTHOUGHthat boron diffusion had not been studied quantitatively and systematically prior to 1948, a few qualitative observations which were made by following the diffusion of boron into iron packed in ferro-boron1-3 suggest that boron obeys normal diffusion laws and that the rate of diffusion increases with increasing temperature. The claim of Cornelius and Bollenrath1 that boron does not appear to influence the rate of carbon diffusion has recently been substantiated by Wells, Batz, and Mehl.4 Calculations based on data from the paper by Campbell and Fayv indicated that the diffusion coefficient (D) for boron in iron at 900°C is approximately 3x10 sq cm per sec; a value of 2x10-7 sq cm per sec at 1038°C has been reported by Digges et al in connection with decarburizing experiments on a commercial boron steel containing 0.43 pct C. During the period 1948 to 1950 several diffusivity constant (D) values for the diffusion of boron in the y phase of iron and steel and a number of solubility values for boron in both a and y phases were reported. It was concluded tentatively as a result of Metals Research Laboratory studies that D values for boron in y and a phases are about the same as for carbon in the comparable phasesa and that carbon up to 0.4 pct did not affect the rate of diffusion of boron in y iron above 1000°C within the limits of experimental error. Whether saturation of the y or a phases with carbon would significantly affect rates of diffusion of boron through them was then and still remains in doubt. The best estimate of Q (activation energy) was reported to be about 25,000 cal, somewhat lower than that for carbon in y iron. The solubility of boron in y iron at 1000°C was thought to be higher than 0.004 pct B but not as high as a more recent analysis of available data shows it to be. The solubility of boron in a iron at 700°C was reported to be 0.0004 pct B, but it would not have surprised the authors if the true solubility value is actually lower than this. Breaks in diffusion curves which were not understood when first obtained prior to 1950 have now been recognized as indicating solubility limits, and these are included in the present paper. Experimental Procedure Two methods were employed in an effort to determine diffusion coefficients (D) for boron in austenite. Early experiments involved the use of welded couples prepared in accordance with the procedure of Wells and Mehl,' but when the results of these experiments proved to be unsatisfactory for calculating D values, studies were continued by means of deboronizing experiments. In both cases, boron analyses following the diffusion anneal were carried out spectrographically and all D values were computed using the Grube solution of Fick's law. The precision of the spectrographic method used proved to be about equal to that reported by Corliss and Scribner" —average deviation from the mean about 5 pct of the amount present when the boron content is 0.003 pct. Concentration-penetration curves obtained from spectrographic analyses of welded couples generally indicated that practically no boron was transported across the weld interface during the diffusion anneal. Furthermore the concentration-penetration

Jan 1, 1954

By Gearge C. Wallick

This paper describes experimental procedures for the calibration of capillary tubes to be employed as comparison standards in gas flow-rate measurements and considers several types of flow which were observed in the calibration of seven capillaries of varying diameter. It is shown that under certain experimental conditions deviations from Poiseuille flow are observed which may not be attributed to turbulence, and that this flow behavior may be described empirically by introducing the classical kinetic energy correction into the Poiseuille equation. INTRODUCTION Techniques have been developed for the measurement of the volume rate of flow of nitrogen through glass capillary tubes as a function both of the differential pressure applied and of the absolute gas pressure. Capillary tubes thus calibrated are frequently used to determine the rate of gas flow through a porous sample in the measurement of slip-corrected permeability. The purpose of this note is to describe the calibration procedure and to discuss some observed deviations from the ideal flow behavior predicted by the Poiseuille equation. EXPERIMENTAL PROCEDURE The volume flow rate of nitrogen as a function of the differential pressure was determined experimentally for a series of seven glass capillary tubes of varying diameter. As is shown in Table 1, the capillary radii in the series ranged from 0.004 cm for K1 to 0.07 cm for K7. The capillary tubes were cut from capillary tubing purchased on special order from several manufacturers and the bore radii were determined by microscopic measurement. The gas volume flow rate was measured for each capillary tube at a series of differential pressures in the range from 0 to 3 cm of mercury and at average absolute pressures of 1.0, 2.5, 4.0, and 6.0 atm. Experimental Procedure for Small Capillaries A schematic diagram of the apparatus used to calibrate the three smallest capillaries, Kl, K2, and K3, is shown in Fig. 1. By means of a standard Ruska Instrument Corp. volumetric pump (equipped with a synchronous motor drive, two stages of gear reduction, and a quick-change lathe gear box), nitrogen was displaced by mercury from a metal cell immersed in a constant-temperature bath. The pump, the line to the cell, and a part of the cell were filled with mercury. As mercury was forced into the cell, it displaced nitrogen which passed through the capillary tube being calibrated and into a large container with a volume of approximately 30 liters. Since the volume of this container was very large compared to the total volume change of the gas resulting from the action of the displacement pump, the absolute pressure of the system was essentially constant throughout any one run. Prior to any determination this pressure could be set at any desired level by means of an auxiliary nitrogen cylinder. The differential pressure across the capillary was measured with a Meriam Red Oil manometer and recorded together with the corresponding pump displacement rate which was equal to the gas flow rate. By repeating this process for a series of different displacement rates at each of the absolute pressures of interest, the data necessary for plotting the calibration curves for capillaries K1, K2, and K3 were obtained. All calibration measurements were made in a constant temperature room to minimize errors due to temperature fluctuations. In each run. the flow was maintained until equilibrium was established. Experimental Procedures for Large Capillaries The flow rates through Capillaries K4, K5, K6, and K7 required to obtain the pressure drops desired were larger than could be obtained from available constant displacement pumps, and it was thus necessary to employ an alternative calibration procedure. The arrangement of apparatus used in calibrating these capillaries at an average pressure of one atmosphere is shown in Fig. 2. Each capillary was calibrated by flowing nitrogen through the capillary and recording the differential pressure as a function of the flow rate. 'The differential pressure was measured with a Meriam Red Oil manometer and the flow rate was determined by collecting the effluent gas over water at constant pressure and recording the increase in volume per unit time after an equilibrium had been established. Appropriate corrections were made for the

Jan 1, 1953

RECENTLY seven Boy Scouts were chosen from all the troops in the United States for their all-around ability, excellence in' scouting, and special ability as writers. Two of the members of this selected group were sons of In-stitute members. In the accompanying illustration, Ber-nard Queneau, son of A. L. J. Queneau, of the U. S. Steel. Corp., can be seen at the extreme left, just behind Theo-dore Roosevelt, who is shaking hands with the boy next to. Carl Zapffe (standing in the middle with his hands behind him), the son of Carl Zapffe, manager of the iron ore prop-erties of the Northern Pacific Railroad.

Jan 6, 1928

By T. F. Witherbee

THE following calculation of heat requirement covers the working of the furnace from January 25th to February 14th, inclusive. A short time previous to the first date the furnace had been working rather badly, so that 300 lbs. of ore and 500 lbs. of limestone were taken off. Within the time mentioned the quality of the iron passed

Jan 1, 1877

Brushy Creek mine is located near the center of a linear, 40 mile long belt of mineralization that extends south from St. Joe Minerals Corp.'s Viburnum division. The mine area includes a segment of 5.4 miles long of this new mining region along which eight mines are presently operating. The geology of the area is relatively simple; the rock formations have not been disturbed through folding or extensive faulting.

Jan 7, 1973

By Bryan J. Travis, Thomas L. Cook

INTRODUCTION Our growing concern for adequate and secure sources of energy and minerals has stimulated vigorous exploration for new sources, research toward a better understanding of geological processes, and development of new extraction technologies. The need for control, or at least prediction, of subsurface fluid flow is important for many of these technologies for example: primary, secondary and tertiary recovery of oil; ground water and waste management; in-situ fossil energy extraction (oil shale, coal, tar sands); and solution mining of uranium, copper and other minerals. These technologies, especially the last two, are characterized by highly complex systems. A partial list of the physical processes occurring would include flow in porous/fractured media, multi-phase and multi-component flow with heat transport, chemically active fluids and soils, tracers, diffusion and dispersion, fracturing and dissolution. A great deal of understanding of how these processes behave and interact can be obtained from models. MODELS Theoretical models are valuable because they: 1) provide a frame of reference for interpreting results of laboratory and field experiments; 2) once validated by experiments, allow a variety of geometries, injection/production strategies, etc., to be examined (at relatively low cost) for efficiency and stability; 3) can provide guidance to the design of experiments and field operations. Most models are based on the fundamental principles of mass, momentum and energy balance. But from this starting point, many paths can be taken. For example, there is the theory of Payatakes (1973) which concentrates on the microscale dynamics. In this approach, the rock or soil matrix is represented by a complex of characteristic channels (such as periodically constricted smooth tubes). Detail of flow within the characteristic channel is calculated very accurately. A difficulty with this model is that description of a representative channel can require several parameters which may not be easily measured. Also, it is not clear how the channels can be combined practically to model a large scale flow. Another type of model is the "global" one described by Bear (1972). Here, the continuum equations for conservation of mass, momentum and energy are averaged over a distribution of pore channels, resulting in a set of conservation equations in which the small scale structure of the medium is replaced by quantities such as porosity, permeability, dispersion coefficients and tortuosity. This approach allows computation of large scale flows. However, additional constitutive equations are needed which relate averaged quantities such as permeability to observables such as local saturation, particle size distributions, and others. An important difference between models is the way they handle the momentum equation. Payatakes' model solves the full equation. In others, it is replaced by a simpler relation such as Darcy's law (valid for slow flow rates) or by Forchheimer's equation which extends Darcy's law to higher flow rates. These simple relations can nevertheless match a great deal of experimental data (Dullien 1975). The permeability term which appears in Darcy's law and in Forchheimer's expression has been related to other quantities such as porosity and particle surface area. The Kozeny-Carmen equation is a well-known example, valid for some ranges of porosity and particle sizes and for some materials. Several other semi-theoretical, semi-empirical formulations have been devised, none of which are entirely satisfactory. One goal of researchers has been the ability to predict permeability of a porous material from basic measurable quantities such as grain size distributions without recourse to adjustable parameters. This effort has proceeded from consideration of distributions of idealized, non-intersecting channels, to intersecting channels, to consideration of both distributed pore radii and pore neck radii. This last approach has been used successfully to predict permeabilities (ranging over several orders of magnitude) in sandstones (Dullien 1975). Additionally, studies on explicit networks of channels (e.g., Fatt 1956) and percolation theory (e.g., Larson et. al. 1981) have been used to examine interconnectivity effects in porous media with the hope of eventually being able to predict permeability accurately. To be of more than theoretical interest, a model must be compared s controlled laboratory conditions where boundary and initial conditions and relevant material properties can be accurately determined. Also, extraneous forces can be eliminated so that the interactions between processes of interest can be clearly seen and flow models can be vigorously tested. In contrast to the well-defined environment and

Jan 1, 1982

The figures given here were received through the courtesy of the Bataafsche Petroleum Maatschappij and the Standard-Vacuum. There is an increase in production for the year of approximately 4½ million barrels. In November the average production indicated that during the year 1935 the total production would probably exceed 50 rnillion barrels. To maintain this production, only 106 wells were drilled during the year, mainly in South Sumatra.

Jan 1, 1935

[ ] [LOCAL SECTION CODE (Numbers indicate Sections) No. Section LI Alaska L50 Adirondack L2 Arizona L58 Arkansas L84 Balcones L66 Billings Petr. L3 Black Hills L4 Boston L76 Caracas L5 Carlsbad Potash L6 Central Appal. L60 Central N. Mex. L7 Chicago L79 CIM-AIME Calgary L82 CIM-AIME Edmonton L8 Cleveland L9 Colorado]

Jan 1, 1961

[Indexes to Vols. 1-35, 36-55, 56-72, 73-117 (set of 4 Indexes). DIVISIONAL TRANSACTIONS AND SPECIAL EDITIONS Coal Division Volume, 1930, 1931, 1932, 1934, 1936, 1938, 1940, 1942, 1944, 1946. Institute of Metals Division Volume, one each year 1927-1946. Iron and Steel Division Volume, one each year 1928-1946. Metal Mining, Nonmetallic Minerals and Mining Geology Volumes, 1934, 1935 (Out of print), 1937, 1940,* 1941, 1943.ø]

Jan 1, 1946

By J. E. Coyne, L. E. Tanner, J. E. Boyd

In recent investigations of the isothermal transformations of the retained 0 phase in a titanium alloy having 13 pct V, 11 pct Cr, and 3 to 4 pct Al, there have been indications that the w transition phase is the initial decomposition product at temperatures below about 950°C (510 c).' This metastable phase, found in a number of titanium-base alloys rich in stabilizing elements and known to have an adverse effect on their ductility and toughness, is not easily observed by the usual experimental techniques. Since wis coherent with the /3 matrix,495 distinct interphase boundaries are not revealed metallographically. However, in some cases, an etching effect (i-e., a "mottled" /3 surface) poorly resolved by light microscopy has been found to correspond with the presence of w.6 X-ray diffraction examination has generally been the most suc- cessful means for identifying this phase and crys-tallographic determinations have been made.4'5 Dynamic elastic modulus7 and electrical resistivity measurementse have also aided in the identification of w. In the current study, the electron microscope was utilized to examine microstructures in aged Ti-13V-11Cr-3A1 that were unresolvable by light microscopy techniques. Using negative parlodion replicas (shadowed with chromium at 27 1/2 deg) examination was made of various transformation

Jan 1, 1962

By Daniel Martin

THE dendritic pattern of steels shown by deep etching is used exten-sively as a guide in the inspection and control of the great majority of steels used in ordnance construction and for many applications in indus-try. The value of macroexamination lies in the fact that it enables a qualified observer to make deductions concerning the general quality of relatively large pieces of metal. Not the least of these general character-istics is the nature and extent of the dendritic segregation in the steel, either in the cast condition or after mechanical or thermal treatments. PREVIOUS WORK Detailed methods for macroetching were outlined by Yatsevitch1 and have been standardized by the American Society for Testing Materials. A comprehensive study of the occurrence, origin, and the chemical and crystalline nature of the dendritic structure was given by Keshian.2 The marked persistence of dendritic segregation in nickel steels is fully recognized and has been discussed by Sauveur and Reed' and by others. Very little, however, has been written on the effect of the various elements on the macrostructure of steels, and the purpose of this report is to submit evidence concerning the influence of chromium, nickel and molybdenum on the macrostructure of some 4 by 4-in. ingots cast and treated under closely controlled conditions.

Jan 1, 1939

By John Fritz

Gentlemen of the American Institute of Mining Engineers : I desire to thank you sincerely for the distinguished honor you have conferred upon me by electing me to the presidency of this society, a position which in the past has been filled by some of our most distinguished and ablest members, men eminently qualified by education, practical training and a business ability which has enabled them not only to fill the position with credit to themselves, but as well with honor to the society. In deference to a custom long established, by which the presidentelect is expected to read a paper on some subject with which he is more or less familiar, I have thought that a brief review of the methods employed in the manufacture of iron, as witnessed by myself, and reaching back to 1838, would interest some of our older members and give our younger ones a glimpse into the trials and difficulties encountered in those early days by the pioneers in this great industry. In 1840, 12 to 20 tons of pig-iron was the make of a furnace per week—at this time from 1200 to 2000 gross tons. In 1840, 3 to 4 tons No. 4 wire rods per turn. They have lately made 176 gross tons in 11 hours. In 1840 I have not the quantity of puddled iron made; but it was

Jan 1, 1895

By K. Matsuda, H. Tanaka, M. Mamiya, H. Majima

Copper cementation was studied from both thermodynamic and kinetic aspects. The temperature effect of copper cementation, which has been recognized as an anomalous result, and the rate enhancement phenomenon observed after the initial linear step are, in particular, focused in this work. The main results obtained are as follows; 1) Free energy changes of copper cementation reactions, calculated by the use of the "Correspondence Principle" of Criss and Cobble are rather insensitive to temperature. 2) A Flow-cell assembly consisting of a special cupric ion electrode, a calomel electrode and a potentiometer is particularly useful for the continuous measurements of copper cementation rate. 3) Two first-order reaction rate constants for the CU2+- Fe system were successfully determined by the use of the flow-cell assembly. 4) Activation energies determined for the initial rate and the 9 maximum rate of CU2+ - Fe system are both 4.6 kcal/mole. This fact suggests that the mechanisms of the initial reaction and the final reaction are essentially the same and both reactions are rate controlled by the diffusion in a boundary layer. The difference in the rate constants of them may fie explained by the effect of the nature of surface deposits. 5) Qualitative explanation of the rate enhancement phenomenon from the initial rate was successfully made by applying Bockris "Penetration Model."

Jan 1, 1976

By Franklin R. Carpenter

Pyritic smelting, so-called, as practiced in the Black Hills is pyritic smelting only in the sense that Dr. John Percy uses the expression in his " Metallurgy of Silver," where he describes a process for smelting dry silver-ores in connection with iron pyrites, to form a regulus. The ores treated by this process in the Black Hills are very siliceous, averaging about 74 per cent. of silica, from 10 to 20 of iron oxide, 4 or 5 of alumina, and from 2 to 4 of lime. In 1889, while Dean of the South Dakota School of Mines, I took up the question of their smelting. There were neither copper- nor lead-ores in the Hills; hence pyrite and pyrrhotite, of which there are large deposits, were employed to form a regulus. This mixture of pyrite and pyrrhotite, besides being absolutely barren of gold and silver, carried an average of 30 per cent. of silica. The only basic material available as a flux for the great excess of silica in the ores and in the pyrite was a dolomitic limestone. Moreover, the local coke gave 24 per cent. of ash, 60 per cent. of which was silica—as unpromising a set of conditions as can well be imagined. We had before us the examples of Mr. W. Lawrence Austin, of this Institute, who had experimented at Toston, Montana,"

Jan 1, 1901

By Wayne Anderson

Regarding the technical paper by Thomas E. Finch and Edward L. Fidler, "Recovery of Stray (Thin) Seams in Western Coal Mining." I would like to comment on this subject. In western Canada, most strip mines encounter thin seam coal or rider seams. Although the paper addresses the problems and costs associated with the recovery of this coal, it does not take into account what the savings are. Without looking at the savings, the "Total Objective" is of course not clear. I feel that in a stripping operation the mine can spend per ton (of the thin seam) up to their dragline stripping costs per ton to recover a rider seam or thin seam. The reasoning behind this is simply that this is the price the mine will have to pay to expose an equivalent amount of coal without the recovery of these thin seams. If the mine can recover a rider seam or thin seam for less than the dragline operating costs per ton, a savings will be realized. By recovering a thin seam or rider seam, the life of an ore body is extended by that amount of coal not thrown away. In addition, the cost of land acquisition, associated permits, capital, and reclamation will be reduced as more coal is delivered for a given area. When the above points are considered, the recovery of these thin seams can be very profitable and indeed worth recovering.

Jan 1, 1983

NORMAN B. PILLING (author's reply to discussion *).-The discussion by Mr, Bassett raised one or two points that deserve further discussion. The printed figure for the lead content of the copper used was 0.015 per cent. and not 0.15 per cent., upon which his comment was based. A copper having the latter figure would, of course, be quite unusual. Mr. Bassett takes exception to the writer's statement regarding the distribution of cuprous oxide in wrought copper and states that "the FIG. 1.--ROLLED AND ANNEALED SHEET. ETCHED WITH AMMONIA AND HYDROGEN PEROXIDE. X 75. eutectic of copper with cuprous oxide is usually found between the crystals of pure copper, whether in the cast or the wrought form." While it is very well known that during the solidification of cast copper the cuprous oxide is segregated completely as an envelope of cuprous oxide-copper eutectic around the crystals of copper free from oxide, it is the writer's opinion that, as a result of repeated rolling, this eutectic structure is quite destroyed and the small particles of cuprous oxide become widely scattered, and in the recrystallization following, during annealing, the rearrangement of the grain boundaries takes place with much indifference to the actual distribution of these particles. In the accompanying micrograph, taken from a rolled and annealed sheet, the random distribution of the small cuprous-oxide particles with reference to the location of the grain boundaries may be seen.

Jan 3, 1919

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

By G. V. Sullivan, B. E. Davis, T. O. Llewellyn

The Bureau of Mines, US Department of the Interior, conducted studies to recover phosphate from four dolomitic southern Florida deposits not currently mined. The samples contained 5.8-10.2% P205 and 1.7-4.8% MgO. Chemical analyses of sized fractions indicated that no pebble concentrate, +1.2 mm (+14 mesh) could be produced from these samples. A scheme was developed that consisted of desliming, grinding, scrubbing, and redesliming the ore to produce a flotation feed. Conventional one-step fatty acid fuel oil batch flotation tests on the samples resulted in concentrates containing 29.0-31.3% P205 at flotation recoveries ranging from 72.4 to 96.1% of the flotation feed. The MgO content of the concentrates ranged from 0.47 to 1.36%. Continuous flotation of the Manatee No. 2 sample indicated that commercial-grade phosphate concentrates analyzing 31.3% P205 and 0.55% MgO could be produced with a flotation recovery of 89.9%. The MgO content of concentrates obtained from the Manatee No. 1 and Hardee samples was 1.20 -1.36 %, respectively. Leaching with aqueous SO2 reduced the MgO content of these phosphate concentrates to 0.5 and 0.8%, but with a concomitant loss in phosphate recovery of about 10%.

Jan 1, 1985

By Lawrence Adler

The authors are to be complimented on using a novel and potentially helpful technique to analyze the effects of mine roof trusses. However, some criticisms of their application and analysis seem appropriate to further its acceptance. This discussion will deal with the normal structural analysis format covering: 1) material, 2) load, 3) structure, and 4) analysis. It will then briefly review the testing procedures and finally cover miscellaneous items.

Jan 12, 1978