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By W. J. Wrazej

THE measurements on the formation of multi-layered scales on pure iron1 and the metal -lographic examination of the produced layer of FeO, Fe,O,, and Fe2O3 shown in micrographs2 throw much interesting light on this apparently well-known subject. Professor Paidassi announced2 that in a few months7 time further results are going to be published with regard to the growth of Fe2O3 and Fe2O3 layers on an Armco iron as a function of temperature. Because of the very thin layers of Fe2O3 which are shown by Paidassi (Fig. 10 of ref. 2) when samples were scaled in air at 700°C for 4 hr and because this is not in agreement with the present author's previous observations, the following experiment was recently carried out. Polished cylindrical samples 13/64 in. in diam and 1/4 in. long from electrolytic iron used for spectro-graphic work (Hilger, H.S. Iron rods, F.693) and an Armco iron sample 1/4 in. in diam of the same length were suspended in a muffle furnace on Nichrome wire and annealed in air for 4 hr at 700°C 5OC. Because of the known easy peeling off of the Fe2O3 layer which is mainly in the form of powder (purple red dust on the surface) the samples were protected against any draft and shock. After annealing, the samples were cooled in air and placed in the mount-

Jan 1, 1954

By Charles Austin

IT has long been known that plain high-carbon steels may be susceptible to graphiti-zation below the A, critical, but no data have been available to indicate what factors cause and tend to inhibit graphite formation. Two recent publications1,2 have shown that the factors controlling graphitization below the A, are different from those operating above the A, inversion where commercial graphitization of malleable iron begins. Furthermore, for plain high-carbon steels graphitization below the critical point does not appear to be related to ordinary chemi-cal analyses. Many years ago it was recorded' that the rate of graphitization at subeutectoid tem-perature is not a maximum just below the A, critical, but at some lower temperature, which Austin and Norris have shown to be about 670°C. Indeed, work done in our laboratory has demonstrated that it is im-possible to spheroidize certain steels in the temperature range of 650° to 710°C. with-out the formation of considerable amounts of graphite. However, if the temperature is maintained just below the A, (720°°C,) these same steels may be completely sphe-roidized at constant temperature. In previous studies1,2,4 on 1 per cent plain carbon steels graphitization was en-countered during prolonged tempering. The limited number of steels studied did not provide sufficient data to permit adequate study of the factors controlling this graphi-tization. Accordingly, a limited statistical investigation was undertaken, utilizing 18 steels of similar chemical analyses, fur-nished by four steel companies, who also supplied information regarding the history of manufacture.

Jan 1, 1940

By Claus Guenter Goetzeil

(New York Meeting, February, 1937) The object of this investigation was to determine whether silver alloys could be used instead of the currently employed insert of high-expansion Average Coefficient per Deg. C. over Range 20° to 200° C. Pure aluminum..................................... 24.6 X 10-6 Cast low-expansion Si-Cu-Ni-A1 piston alloy............ 20.0 X 10-6 High-expansion austenitic Cu-Ni cast iron.............. 19.3 X 10-6 Cast steel (0.25-0.35 C, 0.40-1.0 Mn).................. 12.6 X 10-6 Cast iron (3.15 total C, 2.16 Si)....................... 12.8 X 10-6 Pure silver.......................................... 18.9 X 10-6 austenitic ferronickel alloy, to reduce the wear of ring grooves in light metal pistons. A typical example of a piston containing a ferronickel insert is shown in Fig. 1. The high coefficient of expansion of silver made it worthy of consideration, while the small size of the insert would render its use feasible in Germany as an emergency measure. The coefficients of linear expansion of several metals and ailoys are as shown in the table above. Obviously the melting point of the insert must be high enough to prevent it from melting when the light alloy is cast around it. This imposes a lower limit of about 850" C. for the solidus of the silver alloy. Pure silver melts at about 961" C., so that the tolerable depression in the solidus is rather small. To avoid deformation of the insert during use a Brinell hardness number of at least 60 appears necessary.

Jan 1, 1937

By Francis A. Thomson

But little has been written concerning the camp of Republic. In 1900 Chatard and Whitehead 1 reported the results of some experiments with samples of ore from the Republic mine, and a few years later Fritz Cirkel2 described the construction, operation, and results attained in the mill at the Mountain Lion mine. From time to time brief articles, mostly of a semi-technical nature, have appeared in the Engineering and Mining Journal and other mining periodicals. The general geology of the camp, especially in regard.to its areal features, has recently been ably described by Joseph B. Umpleby.3 To bring to mind the general features of the district it may perhaps be well to review briefly some facts in regard to it, before discussing the treatment of the ore. I. History and Production. The town of Republic is situated in the NW. corner of Ferry county, about 25 miles south of the International Boundary, on the head-waters of the San Poi1 river, in what was formerly the " north-half" of the Colville Indian reservation. On Washington's birthday, 1896, this portion of the reservation was thrown open to mineral location, and within a few weeks important discoveries had been made. The present Eureka mining-district was organized, the camp grew apace, and consignments of ore were shipped by wagon to Grand Forks, 30 miles away; or to Marcus, a somewhat greater distance. It is reported that the first 1,500 tons shipped from the Republic mine uetted the owners $160 per ton, after being hauled

Jan 1, 1913

By Harold Cook

Discussion of the paper of HAROLD EARLE COOK, presented at the New York meeting, February, 1916, and printed in Bulletin No. 110, February, 1916, pp. 375 to 400. ALBERT SAUVEUR, Cambridge, Mass.-I think we must all agree with Lieutenant-Commander Cook when he says that there is a great deal of room for improvement in the annealing of steel castings and that better results would be attained if the annealing were conducted in closer agreement with scientific requirements. Whether even a carefully annealed steel casting can ever be made the equal of a steel forging of good quality is still a debatable question. Nevertheless, we all realize that very greatly improved results can be attained by careful annealing. Lieutenant-Commander Cook refers to some requirements calling for annealing steel castings above the Ac1 point. He is undoubtedly right where he says that this should be the Ac3 point. Take, for example, a steel casting containing, say, 0.35 per cent. of carbon, having a very coarse structure made up of coarsely crystalline ferrite. If this is heated just above the Ac1 point the ferrite remains, of course, just as it was before, while the pearlite is converted into a solid solution, austenite. Upon cooling, all this austenite is again converted into pearlite, or sorbite, while the coarse structure of the ferrite remains unchanged and the annealing has accomplished very little. It is therefore surprising that the requirement of annealing above the Ac1 point should appear, in these specifications.

Jan 5, 1916

By E. T. Turkdogan, P. Grieveson

Experimental results are given for the rate of oxidation of ferrous iron to ferric iron in pure molten iron oxide by carbon dioxide + carbon moloxide mixtures at 1550°C. It is shown that the rate-controlling process is the interdiffusion of iron and oxygen atoms within the melt. The inter-diffusivity of iron and oxygen in the melt is obtained from the results and the value of (5.0 * 1.0) x 10-5sq cm per sec is recommended for the temperature of 1550°C. Similarly, it is also found that the rate of reduction of molten iron oxide is con -trolled by diffusion in the melt; however, apparent interdiffusivity values from these experiments are 10 to 20 pct higher than those obtained in the oxidation experiments, by virtue of convection arising from density difference. The results of the oxidation experintents are used to calculate an estimated self-diffusivity of iron in molten iron oxide of (1.5 * 0.5) x sq cm per sec. BECAUSE of the industrial importance of iron oxides, the study of the kinetics of both the reduction and oxidation of the solid oxides has received a great deal of attention. However, knowledge of the kinetics of similar reactions in the liquid state is very meager. Dancy 1 studied the kinetics of reduction of molten iron oxide by carbon in pig iron and found that the reaction is very fast. It was concluded from the results that the reduction of molten ferrous oxide is a first-order reaction up to 80 pct reduction, while

Jan 1, 1964

By H. M. Fisher, R. E. Snow, S. C. Sun

RAPID colorimetric estimation of the amount of transparent minerals has been applied success- fully to instream mill products at the cryolite flotation plant of the Pennsylvania Salt Mfg. Co., Natrona, Pa. Apparatus used was a Bausch & Lomb monochromatic colorimeter. The optical assembly of the colorimeter, shown in Fig. 1, passes light from a 6-v, 32-cp, prefocus incandescent lamp through two condensing lenses, a heat-absorbing filter, an aperture-control diaphragm, an interference filter, and a sample container. The light finally strikes a barrier-layer photocell and the output current of the photocell is measured by a galvanometer. The engraved index line of the collective lens, located between the lamp and the galvanometer, is imaged upon the transmission scale of the colorimeter by the galvanometer mirror. Reflected light from the galvanometer mirror, the position of which is determined by the output current of the photocell, enables reading of percent transmission throughout the mineral sample being tested. The colorimeter, Fig. 1, was standardized as follows: 1-The colorimeter was connected to a Sola constant voltage transformer, A, of 6-v output operated from a 110-v ac supply. 2-Turning the toggle switch, C, illuminated the transmission scale, B, and the control knob, D, was adjusted with a blank in the optical system until the hairline on the scale read zero. 3-A No. 430 interference filter, E, was inserted into the filter channel, F. &--A test tube, G, containing 7 cc of distilled water was pressed into the sample space, H, and the fine adjustment knob,

Jan 9, 1954

By Richard S. McCaffery, Joseph F. Oesterle, Oscar O. Fritsche

The method of obtaining the data on which this paper is based is explained in detail in the paper on Determination of Viscosity of Iron Blast-furnace Slags.' The work was made possible by a grant of funds from Engineering Foundation, and it gives the results now obtained, continuing the general subject of our previous work and reported in former papers2 The data experimentally obtained are in the form of a temperature-viscosity curve for any slag of particular composition. (See Fig. 1.) From these curves, the viscosity of a slag of a definite composition and at a definite temperature is taken off and is plotted on a plane triaxial diagram showing compositions of silica lime and alumina on a plane representing constant-magnesia content (Fig. 4). The temperatures at which these results were plotted are 1300°, 1350°, 1400°, 1450°, 1500°, 1550" and 1600" C. and since the constant magnesia plane sections were an even 1 per cent. magnesia apart, magnesia analyses not of even unit magnesia composition were projected to these even unit magnesia planes. For example, 1.78 per cent. magnesia and 2.35 per cent. magnesia were projected to the 2 per cent. magnesia plane. The triaxial diagrams on which this first plotting was made were drawn on celluloid sheets, a transparent material on which it was easy to draw. When all the experimental work was plotted on celluloid in this way, the sheets representing a definite temperature were stacked in the proper order and were examined by transmitted light. Where

Jan 1, 1932

By B. Ladanyi, B. Hoyaux

A first requirement for assessing the safety of a rock slope, either artificial or natural, particularly if the rock behaves in an elastic-brittle manner, is a propw knowledge of the distribution of stresses within the slope and their development with time and advancement of workings. There are a uumber of different methods that can be used, in principle, for obtaining this information, such as (1) stress measurement in situ, (2) photoelasticity,1 (3) analytical methods, and (4) numerical methods. In cases where the stress distribution cannot be obtained by classical analytical methods, as in the one considered herein, either photoelasticity or numerical methods are norrnally used. However, actually, due to the rapid development of high-speed computers, increasing preference is given to the numerical methods. Among the latter, the most successful ones, to date, for determining the stress distribution in slopes have been (1) the finite difference method,2-4 (2) the lumped parameter method,5 and (3) the finite element rnethod.6 However, for determining gravity stresses in a natural rock slope, only the finite difference method has been used until now.7,8 A solution of the same problem by the finite element method will be shown here in which a particular reference is given to the development of tensile fracture zones within the slope. FINITE ELEMENT METHOD The stress analysis using the finite element method originates from an extension of the matrix analysis of structures.9 It consists in decomposing a continuous medium, assumed herein to be homogeneous and isotropic,

Jan 1, 1972

By R. P. Smith, L. S. Darken

FOR a high-purity iron-carbon alloy, the phases existing at equilibrium at temperatures slightly above the temperature of the metastable eutectoid are austenite and cementite (hyper-eutectoid) or austenite and ferrite (hypo-eutectoid) and those below the eutectoid temperature (carbdn content > 0.02 pct) are ferrite and cementite. Such an alloy, held in a carefully controlled and measured temperature gradient (about 1 cm per deg) which includes the eutectoid temperature, then quenched and examined metallographicall.y, provides a precise measure of the eutectoid temperature. The samples were hollow cylinders approximately 1.3 cm OD, 0.63 cm ID, and 2.5 cm long, which had been carburized to the desired carbon content at 1000°C with an appropriate hydrogen-methane mixture. In order to cool the samples to room temperature with a minimum change of carbon content and absence of cracks they were quenched in a Cerro Bend bath at 480°C, followed by a water quench to room temperature. Three cylinders were suspended in the furnace1 in a purified helium atmosphere, by a closed end, thin wall, silica tube which also served as a thermocouple well. The top and bottom cylinders served only as a means of making the temperature gradient along the center cylinder more uniform. The temperature was determined with a platinum-platinrhodium thermel calibrated by comparison with a thermel certified (* 0.5OC) by the National Bureau of Standards. After holding in the temperature gradient for 24 to 72 hr the samples were quenched in Cerro Bend at 480°C, followed by

Jan 1, 1960

By S. E. Bronisz, J. O. Brittain

Experiments have been carried out to study the effect of an applied stress on strain aging in steel. It was found that the stress-induced strain aging reaction proceeds rapidly in the temperature range of 0° to 60°C. The variation of stress-induced strain aging with plastic strain, aging time, and temperatures is reported. The activation energy for the stress-induced strain aging was found to be 10,000 cal per mol for the steel used in this investigation. VARIOUS observations1-5 have been made of the influence of an applied stress upon the yielding of iron and steel. However, there have been only cursory studies of the effect of an applied tensile stress upon strain aging in iron and steel1,2 The following represents the results of a preliminary study of strain aging as influenced by the application of an external tensile load during the aging process. For the most part, previous experimental work on strain aging can be classified into two parts. First, the experimental technique involved a direct determination of mechanical properties of a suitable specimen that has been plastically deformed to a constant strain and aged generally at a temperature of the order of 200°C, with the aging times varying from about 1/10 to 2 hr.6-8 The second classification of strain aging experiments involves an indirect determination of strain aging by means of physical property such as electrical resistivity or internal friction as a function of the aging time at a constant temperature and strain.9-12 The latter results have

Jan 1, 1961

By George J. Young

Discussion of the paper of George J. Young, presented at the San Francisco meeting, October, 1911, and published in Bulletin No. 59, November, 1911, pp. 839 to 872. ASKIN M. NlCHOLAS, Melbourne, Australia (communication to the Secretary) : * Professor Young deals with quite a variety of machines and methods, but, strangely enough, makes no mention of the work done by me, although he concludes with the remark that the " thin-cake continuous filters are a decided improvement over the thick-cake filters." As those interested in slime-treatment may consider that I did nothing more than to patent a process, I submit Fig. 1, showing the working-drawings of a machine, made, tested, and proved to work satisfactorily by me early in 1905. This time is prior to any work done in slime-filtration with rotating filters by E. L. Oliver or others. I maintain that a number of appliances now in use for slime-filtration infringe my patents. And after most exhaustive inquiry, I know of no machine or process, prior to my description in 1899,1 that embodied getting rid of the residues by holding them on the cloth with the vacuum, and then discharging them with back-pressure, so as to form a cycle of the operation, the result being continuous treatment. I therefore think that any paper dealing exhaustively with this subject is not complete without a reference to the work that I have done. * Received Mar. 11, 1912. 1 U. S. Patent No. 619,211, Feb. 7, 1899.

Aug 1, 1912

By Robert Glass Cleland

[MINING DIVISION GENERAL WESTERN ADMINISTRATION Harrison M. Lavender, Vice-President and General Manager Charles R. Kuzell, Assistant General Manager Walter C. Lawson, Assistant to Vice-president and Genera1 Manager]

Jan 1, 1952

By D. H. Desy, L. C. Fincher

The magnesium-rich end of the Mg-Ti phase diagram was investigated. The liquidus, solidus, and solvus boundaries to 1 pct Ti were established. All alloys were prepared by saturating molten magnesium with titanium in a consumable titanium crucible under inert gas maintained at 230 psig. The liquidus of the Mg- Ti system was determined by analysis of dip samples taken from 700° to 1300°C under equilibrium conditions in a pressurized inert atmosphere furnace and by analysis of small ingots rapidly poured and quenched from 1400° to 1500°C. The solubility of titanium in magnesium ranged from 0.018 wt pet Ti at 700°C (0.012 wt pet at 650°C by extrapolation) to 1.035 wt pet Ti at 1500°C. The solidus for compositions ranging from 0.03 to 1.00 wt pet Ti was determined to be 650° ± 1°C by thermal analysis. The titanium solid solubility values ranged from 0.08 wt pet at 350°C to 0.19 wt pet by extrapolation to 650°C. The freezing reaction is peritectic. No intermetallic compounds were found in the system; the phase in equilibrium with molten magnesium saturated with titanium was found to be titanium with magnesium in solid solution. Solid titanium will dissolve at least 1.32 wt pct Mg. PREVIOUS investigations of the Mg-Ti system have shown considerable disagreement on the solubility of titanium in liquid magnesium. Furthermore, the solid solubility of titanium in magnesium has not been well established. Liquidus curves for previous work and for the present investigation are shown in Fig. 1. Aust and Pidgeon1 used a dip-sampling method on molten magnesium held in equilibrium with solid titanium under a protective atmosphere to determine the solubility and found that it ranged from 0.0025 wt pet Ti at 651°C to 0.015 wt pet Ti at 850°C. Eisenreich2 introduced titanium into molten magnesium by means of TiCL4 adsorbed on BaCl2. Ingots were then cast at various temperatures. Making the assumption that only the titanium dissolved in magnesium at the time of casting was soluble in H2SO4, Eisenreich determined the solubility of titanium in molten magnesium to range from 0.003 wt pet at 655°C to 0.115 wt pet at 800°C. Eisenreich also determined the solid solubility of titanium in magnesium to be 0.015 wt pet at room temperature and 0.045 wt pet at 500°C. Since the solid solubility just below the freezing temperature for the bulk of the alloy was much larger than the liquid solubility just above the freezing temperature, Eisenreich concluded that the freezing reaction was peritectic. Obinata et al.3 equilibrated molten magnesium with titanium in hermetically sealed titanium containers which were then furnace-cooled. The titanium content of the magnesium was then determined and found to range from 0.170 wt pet at 700°C to 0.85 wt pet at 1200°C. No intermetallic compound was found in the system. The Armour Research Foundation4 determined two points on the solvus by electrical resistivity methods: 0.00057 wt pet at 200°C and 0.0008 wt pet at 300°C. At higher temperatures, data were meaningless with no trends observable. The authors of this report believed that the lack of significant data at the higher temperatures was due to variations in specimen geometry, although there was no positive evidence to verify this supposition. The present investigation was undertaken to clarify the uncertainty in both the liquidus and solvus of the magnesium-rich end of the Mg-Ti system. EQUIPMENT AND MATERIALS The equipment used in this investigation, with some modifications, was essentially that used by Crosby and Fowler5 in their determination of part of the Mg-Zr phase diagram. The equipment, as modified for this work, is shown in Fig. 2. It consists of a sealed furnace chamber which can be pressurized with inert gas so that melts can be made above the boiling point of magnesium at atmospheric pressure. Melts are made by induction heating in a titanium crucible which, after diffusion of sufficient magnesium into the walls of the crucible to saturate the titanium at the sampling temperature, comprises the solid phase in equilibrium with the molten magnesium. Dip samples may be taken with the sampling tube, or the entire furnace may be tilted so that ingots may be poured into a mold in the side chamber. The principal difference from the earlier apparatus is in the thermocouple, which in the present equipment is enclosed in a protection tube and immersed directly in the melt. The tips of both the thermocouple protection tube and the sampling tube, which dip into the melt, are made of high-purity titanium. The 4 1/2-in.-long titanium tip of the sampling tube is threaded into a steel tube, O in Fig. 2, which extends through the top of the furnace. To determine whether the temperature at the tip of

Jan 1, 1969

By R. I. Jaffee, F. C. Holden, H. R. Ogden

ECENT papers dealing with the properties of unalloyed iodide titanium have been directed primarily at the determination of base-line properties for alloy investigations. Early work was limited to a few tests because of the limited availability of iodide titanium at the time. In the results of papers by Campbell et al.,1 Gonser and Litton,2 Jaffee and Campbell,3 inlay and Snyder,4 and Jaffee, Ogden, and Maykuth, data on mechanical properties are presented for unalloyed iodide titanium in the annealed and cold-worked conditions. Data are presented in this paper which show the effects of heat treatment on the structure and mechanical properties of commercially produced iodide titanium. Correlation is made between microstruc-tural variables and the mechanical properties. Experimental Procedures Melting Stock: The melting stock used was as-deposited iodide titanium, produced by New Jersey Zinc Co. The furnished analysis showed the following range of impurities: N, 0.004 to 0.008 pct; Mn, 0.005 to 0.013; Fe, 0.0035 to 0.025; Al, 0.013 to 0.015; Mo, 0.0015; Pb, 0.0045 to 0.0065; Cu, 0.0015 to 0.002; Sn, 0.001 to 0.01; Mg, 0.0015 to 0.002; and Ni, 0.003. Hydrogen content as determined by vacuum-fusion analysis was 0.0091 wt pct (0.44 atomic pct) after arc melting and fabrication. Nitrogen analysis on the arc-melted and fabricated titanium showed a content of less than 0.002 pct N. The average hardness of the furnished stock was Rf 70, or approximately 85 VHN. Melting Procedure: The as-deposited rods were rolled, sheared, and degreased in preparation for arc melting. The charge was arc-melted with a tungsten electrode in a water-cooled copper crucible under a positive pressure of high purity (99.96 pct) argon. The final ingot was approximately 2 in. in diameter and showed no increase in hardness over that of the initial stock. Fabrication: Heating for fabrication was done in air. It was begun by forging the ingot into a 3/4 in. diam rod, at an initial temperature of 1600°F. Scale was removed by sandblasting. The rod was then swaged to 1/4 in. diam at room temperature through a series of 20 dies, with approximately 10 pct reduction in area between each die. An anneal of 1 hr at 850 °C in air was given after the 1/2 in. die, such that the final cold reduction was 75 pct. Sections cut from this rod were used for test and microstructure specimens. Heat Treatment: Heat treatments were carried out in resistance tube furnaces with stainless-steel linings, under an atmosphere of gettered argon. As further protection against contamination, the specimens were packed in titanium turnings in a titanium sleeve. Control experiments have shown negligible hardness increases with this method, indicating that contamination from oxygen and nitrogen is slight. Three cooling rates were employed in this work; these have been designated as water quenching, argon cooling (to simulate air cooling under a controlled atmosphere), and furnace cooling. The cooling rate for an argon cool is 100°C per min for the first minute, with an average cooling rate of 35°C per min over a 15-min period. A furnace cool requires about 10 hr, with an average cooling rate of 3.6oC per min during the first hour, and an average cooling rate of 1.2°C per min over the 10-hr period. Microimpact Test: The specimen adopted was based on the cylindrical Izod Type Y specimen (ASTM, E23-41T). All dimensions were reduced to half scale, including the notch radius. Specifications are shown in Fig. 1. The specimen is held vertically in an adapter and broken as a cantilever beam. Impact tests were run on a constant-velocity (11.34 ft per sec) Tinius Olsen impact testing machine with a total available energy of 100 in.-lb. Tests were made to determine the correlation between this microimpact and the standard V-notch Charpy impact test. Curves showing impact energy as a function of temperature for both impact tests are plotted in Fig. 2. Transition temperatures, when they occur, are about the same for both impact tests. All three titanium-rich materials have the same conversion factor, 10. Tensile Testing: Tensile tests were conducted on Baldwin-Southwark testing machines using the 600, 2400, or 3000 1b range. Specifications for the test specimen were taken from the 1948 edition of the ASM Metals Handbook, and are shown in Fig. 1. Strain measurements were made using an SR-4 resistance gage (Type A-7) cemented to the reduced section in conjunction with a lever-type extenso-meter. Readings on the SR-4 strain indicator were

Jan 1, 1954

By H. M. Fisher, R. E. Snow, S. C. Sun

RAPID colorimetric estimation of the amount of transparent minerals has been applied successfully to instream mill products at the cryolite flotation plant of the Pennsylvania Salt Mfg. Co., Na-trona, Pa. Apparatus used was a Bausch & Lomb monochromatic colorimeter. The optical assembly of the colorimeter, shown in Fig. 1, passes light from a 6-v, 32-cp, prefocus incandescent lamp through two condensing lenses, a heat-absorbing filter, an aperture-control diaphragm, an interference filter, and a sample container. The light finally strikes a barrier-layer photocell and the output current of the photocell is measured by a galvanometer. The engraved index line of the collective lens, located between the lamp and the galvanometer, is imaged upon the transmission scale of the colorimeter by the galvanometer mirror. Reflected light from the galvanometer mirror, the position of which is determined by the output current of the photocell, enables reading of percent transmission throughout the mineral sample being tested. The colorimeter, Fig. 1, was standardized as follows: 1—The colorimeter was' connected to a Sola constant voltage transformer, A, of 6-v output operated from a 110-v ac supply. 2—Turning the toggle switch, C, illuminated the transmission scale, B, and the control knob, D, was adjusted with a blank in the optical system until the hairline on the scale read zero. 3—A No. 430 interference filter, E, was inserted into the filter channel, F. 4—A test tube, G, containing 7 cc of distilled water was pressed into the sample space, H, and the fine adjustment knob,

Jan 1, 1955

By Thomas R. Scotese

A rock mechanics instrumentation and monitoring program was implemented during pillar extraction at Gulf Mineral Resources' Mt. Taylor Mine, the deepest uranium mine in the U.S. Three types of monitoring were employed: (1) drift convergence around stopes (using a portable tube extensometer), (2) stress changes in pillars (using vibrating wire stressmeters in horizontal boreholes), and (3) load changes in haulageways under stopes (using vibrating wire load cells in jack stands). Results include convergence-time graphs, convergence contour maps, stress-time graphs, a stress increase contour map, load-time graphs, and abutment load limit maps. Major factors influencing results include (1) size of pillars around the extraction area, and (2) presence and orientation of a major fault adjacent to one extraction area. These factors, combined with pillar extraction, produced evidence of load transfer over 120 m from a stope measuring only 55 m x 45 m. Vertical stress increases of 7 to 17 MPa (1000 to 2500 psi) within 60 m of the stope were obtained using the stress- meter manufacturer's method. The fault apparently prevented load transfer in the down-dip direction but increased load transfer in the up-dip direction. Convergence rates of up to 1.3 cm/day (0.5 in/day) were measured at two stations. Instruments were generally reliable despite adverse underground conditions. The instrumentation and monitoring program at Mt. Taylor provided a warning system against ground control problems and a characterization of ground behavior for future development and extraction of pillars. Recommendations are made for future mining and instrumentation practices.

Jan 1, 1984

GENERAL GEOLOGIC DESCRIPTION The Escalante silver deposit located in southwestern Utah is an epithermal vein system consisting of a hanging wall and footwall vein, straight along strike and dipping about 1.2 rad (70°). The veins consist of banded quartz and calcite fissure fillings between volcanic wall rock that are silicified for some distance outward from the vein. The walls of the veins are sharp and the silver values are irratically distributed through the various bands within the vein. Only very low grade values are to be found in the wall rock on either side. The portion of the veins above the water table have been somewhat leached, with some secondary enrichment below. The mineralogical zonation is variable due to a fluctuating water table through geologic time. SAMPLE MANAGEMENT AND COMPOSITE ASSAYS Sample data for the deposit was obtained from over 50 diamond drill holes, from channel samples cut at intervals across a drift, and from scattered surface trenches along the out- crop of the hanging wall vein. Fig. 13-1 is a surface plan map showing the vein outcrop and some diamond drill locations. Two cross sections through the vein are shown in Figs. 1 3-2 and 13-3. Nearly all of the diamond drill core of vein material was assayed in 0.3-m (I-ft) lengths, from which weighted composite assays were manually calculated for the horizontal thickness of the vein. The centers of the composited samples were plotted in north and east coordinates and by elevation, and locations and assay

Jan 1, 1980

By Charles H. Kline

Industrial minerals are the Cinderella of the mining I industry. Often considered as just dirt by traditional hard-rock miners and oil drillers, these products nonetheless comprise the second largest segment of the industry and the fastest-growing one. With annual sales of $5.7 billion, industrial minerals make up 22% of the dollar value of U.S. mineral consumption. By contrast, metals account for only 11%. Fuels, of course, are dominant, representing 67%. The dollar values of production and consumption for the three segments of the industry in 1968 are shown in Table I. The growth rate of industrial minerals is shown in Table II. From 1953-1968, the current-dollar value of all U.S. mineral production increased at the average annual rate of 3.8% while that of the gross national product increased at 5.9%. Industrial minerals are the only segment of the mining industry that approached the growth of the overall economy in this period, with production values increasing 5.1% a year and apparent-consumption values 5.6% These data, expressed in current dollars, include the effects of inflation. The growth in U.S. industrial minerals production is even more striking when expressed in indexes of physical production. As shown in Table III, production of all U.S. industries increased by 4.1% a year from 1953 to 1968. The growth in production of stone and earth minerals just matched this figure. By contrast, the average annual increase for oil and gas was 2.2%: for metals, 1.6% : and for coal, only 0.6 %.

Jan 1, 1970

By R. W. Balluffi, B. H. Alexander

RELATIVE diffusion rates of copper and zinc in a brass have been measured in a vapor-solid type of couple with which the amounts of copper and zinc diffusing past inert Kirkendall markers can be obtained by means of a few simple experimental measurements. If inert markers are placed on the surface of copper which is then exposed to zinc vapor from a brass chips, the particles become buried due to outward diffusion of the copper, as shown in Fig. 1. A schematic diagram of such a couple after diffusion is shown in Fig. 2. Consideration of the diffusion flow of copper and zinc shows that the entire hatched area, including the cross-hatched area, is proportional to the amount of zinc diffused inward past the markers and that the smaller cross-hatched area is proportional to the amount of copper diffused outward past the markers. These areas are completely determined by the expansion of the couple, the depth of the buried particles below the surface, and the chemical composition at the specimen surface. As Darken1 has shown, the ratio of diffusivities of copper and zinc is then given by the ratio of these two areas. Polycrystalline copper and two copper single-crystals made by the Bridgman method were prepared in the form of 1.5 cm diam disks approximately 0.5 cm thick with faces plane and parallel. Tungsten particles approximately 0.001 cm in diam were bonded to the surface of each disk by heating 5 hr at 1060°C in vacuo. Each specimen was next

Jan 1, 1953