Search Documents

By Walter Ccallo, Dante Soberon

El área de estudio está ubicada entre los 15° - 16° 30’ Latitud Sur, comprende los departamentos de Arequipa e Ica. En esta área fueron definidas las nuevas unidades intrusivas del Batolito de la Costa (Segmento Arequipa), en el marco de la actualización de la carta geológica a escala 1:50,000. En base al mapeo detallado de rocas intrusivas, estudio petrográfico, geoquímica de rocas e isotopos U/Pb, se logró determinar hasta doce nuevas unidades intrusivas, distribuidas en un tiempo geológico continuo desde el Jurásico medio (168 Ma) al Cretácico superior (92 Ma). Se evidenciaron además nuevas estructuras relacionadas a mineralizaciones de yacimientos tipo pórfido, IOCG (Iron Oxide Copper Gold), vetas mesotermales auríferas y cupríferas.

May 1, 2008

By S. Al-Hassan

The deposit has been exploited for Mn oxide and carbonate since 1916. Known reserves of MnO, however, are almost depleted and the survival of the mine will depend on the exploitation of the carbonate. Kriging, inverse distance weighting (IDW) and cross-sectional methods have been applied to the evaluation of the carbonate resources and reconciliation of the estimates obtained shows that kriging and IDW give almost identical block values. A comparison using conditional probability indicates that there is virtually no difference between the global reserve estimates derived from the cross-sectional and kriging methods. The physical causes of these similarities are highlighted and the problems of dealing with multimodal distributions are discussed together with the difficulties of semi-variogram modelling

Jun 19, 1905

By R. D. Saltsman

This report is in fulfillment of Contract No. H023001.5 awarded to Bituminous Coal Research, Inc., on November 15, 1972. The scope of the work under this contract was to perform a two-phase survey for the purpose of determining the status of work in the following specific areas of industry needs under the Technology Transfer Program and to increase industry's awareness of research efforts under the Federal Coal Mine Health and Safety Act of 1969 6f (P.L. 91-173): 1. Research and development of respirable dust sampling instruments which will more accurately collect the respirable Cuss as defined by the Federal Coal Mine Health and Safety Act of 1969. 2. Development of a better means of control of respirable dust and float dust.

Jan 1, 1973

By M. H. Basiri

The application of aluminum matrix composites, due to their unique properties, is significantly growing in the variety of industries such as aerospace and automobile. In comparison to other light metals, such as magnesium and titanium, aluminum is lower in price. These are the advantages that this metal dominates the others. In this research, first by applying the lost foam casting method, the SiCp/A356 composite was cast in the bottom and side gate conditions with 690°C and volume fraction of 10%. Furthermore, the effects of reinforcement particles (60 µm, 75 µm) were examined. The results present the particles distribution in the side gate methods is more homogeneous than the bottom gate casting method. Also, by increasing the particles sizes, the fading rate in the side gate are reduced from 22% to 19%, as well as from 26.4% to 25.4% in the bottom gate. Key words: Carbide-Silicone Particle, Gating System, Composite Micro-Structure, Foam Casting

Feb 27, 2013

By Nick Rose, Robert Sharon, Mark Rantapaa

Development of the Northeast Layback of Barrick’s Betze-Post open pit commenced in June 2000 and was successfully completed to a height of 400m (1,300 ft) in January 2003. Following a brief exploration drilling campaign at the toe of the final slope, in-pit waste rock backfilling commenced, which will ultimately buttress the final wall. Instability initially occurred in late 2000, above the 5040 Level, as the slope height approached 120m (400 ft). As mining reached the 4680 Level, significant deformation was experienced over a slope height of 230m (760 ft). Slope stability was managed and targeted reserve recovery was achieved by executing complicated modifications of the mine plan, including splitting layback development, well placed offloading cuts, step-outs and mid-slope waste rock buttresses. Decision on timing of these modifying events was often dictated by review of deformation magnitudes and rates determined from continuous slope monitoring records. Design modifications were developed through continuing interpretive refinement of structural geology controls and groundwater distribution, and through stability re-assessments. This document presents an overview of the geological setting and material and strength conditions of the northeast sector of the Betze-Post open pit, followed by development experience leading to design and development of the Northeast Layback. Rock mechanics modeling, design details and geotechnical performance monitoring are then presented. Development experience, stabilizing adjustments to the original design and safety procedures for development and exploration activities are described. The document is finalized with conclusions and acknowledgements.

Jan 1, 2005

By Roy T. Sorensen

As part of its mission to maintain an adequate supply of minerals to meet national needs and maximize mineral production from domestic sources, the Bureau of Mines is investigating the recovery of alumina by hydrochloric acid leaching of kaolinitic clay. Most iron impurities are leached from the clay along with the alumina and must be removed before or during crystallization to aluminum chloride hexahydrate. The thermal decomposition step then provides an alumina product of acceptable iron analysis. Miniplant studies of a Bureau-developed solvent extraction technique, using a tertiary amine in kerosene diluent, have demonstrated that the iron content in aluminum chloride leach liquors can be reduced to levels of less than 0.007 wt-pct (7 ppm), expressed as Fe203. Entrained and dissolved organic matter in the purified pregnant leach liquor from the solvent extraction circuit can be reduced to less than 2 ppm by using a fabric-packed coalescer and subsequent activated carbon treatment. Investigators discovered that a steady buildup of zinc accumulated in the solvent phase within the extraction circuit, proportional to the amount of leach liquor treated. The solvent phase zinc analysis increased by 0.01 wt-pct ZnO for each 1,000 gal of pregnant leach liquor purified.

Jan 1, 1981

By S. Malhotra

Processes for the recovery of manganese contained in low-grade domestic sources are evaluated. Conclusions are based on analysis of literature, technical evaluation and cost analysis. The Nossen Nitric Acid Process, the Sulfuric Dioxide Process rind the Ammonia Leach Process should be developed further as they offer the hunt opportunity for commercialization.

Jan 1, 1984

By E. D. Calvert

The objective of this research was to examine variations in melting and forging practice for four titanium-base alloys and to determine their effect on the resultant product. Of particular interest was the evaluation of the skull-casting technique. The data should serve as a guide to producers and consumers of titanium products. Physical properties of four titanium-base alloys in ingot form and in sheet form were evaluated and correlated, where possible, with variations in the melting and casting procedure. Consumable-electrode melting was used throughout, but arc current and furnace backfill pressure were varied, and ingots were formed both by melting directly into a water-cooled copper mold and by skull melting followed by pouring into a graphite mold. Alloying metal additions for the alloys tested were (1) 8 percent manganese, (2) 6 percent aluminum and 4 percent vanadium, (3) 6 percent molybdenum and 2 percent aluminum, and (4) 16 percent vanadium and 2.8 percent aluminum.

Jan 1, 1962

By W. Lum

In the U.S., flexible metal pipe culverts are designed by ring compression theory because the pipes are capable of deflecting and deriving side support from surrounding ground. For economy, tunnel liners are often designed as flexible structures that depend on the lateral pressure of the surrounding ground to maintain stability. In this paper, simple formulas are presented to determine the maximum deflection a concrete tunnel liner may assume and the ring compressive strength of the deflected liner. A tunnel can then be constructed to work within these limits. Similar techniques may be used to design concrete pipes.

Jan 1, 2010

By R. Tessier, C. R. Larsen

"INTRODUCTIONOn November 10, 1982 Nor and a Inc signed an agreement with Golden Sceptre Resource Ltd. and Goliath Gold Mines Ltd. to construct a mine and milling facility.The Golden Giant mine is located in the Marathon area of north - western Ontario, immediately north of Highway 17 and about- 3.5 km west of Highway 614.With the exception of selected unit processes, the mill was designed for a nominal throughput of 2500 tonnes per day with early operating data to be used to identify sections requiring possible expansion to achieve an ultimate throughput of 3000 tonnes per day.Commissioning of the highly instrumented milling complex which includes crushing, grinding, cyanidation, and carbon in pulp processes commenced in February 1985. After water testing various sub-circuits from grinding through tailings, waste ore was introduced to ensure proper mechanical and electrical operation of process equipment.The first ore was milled as a mixture with waste on March 4, 1985. The first gold bullion was poured April 6, 1985.Initially, ore was only available from mine development at a rate of 700 t/d, which was milled at a minimum rate of 1200 t/d. While regular weekly shut downs of two to three days was useful for mechanical maintenance, changes, and modifications, process tuning was more difficult due to the non-steady operation. As increased quantities of ore became available, regular weekly shutdowns tapered off and process operation improved accordingly. For testing purposes and as ore was available, mill throughput was increased regularly to 2300 t/d and for very short periods of time to nearly 3000 t/d.No major design or operating problem has been encountered to date. The following is a brief description of the milling process and various operating highlights. Process flowsheets are shown in Figures 1 through 6."

Jan 1, 1986

By F. -J. Wodopia

Sustainability of energy supplies has been an issue of general interest for a long time. Whilst in the past the continuous productive use of natural commodities was in the fore, its compatibility with the environment and climate and ultimately also social aspects have recently gained more and more attention. Today many discussions focus on the climate compatibility of individual options to act. Fossil fuels, in particular coal and lignite, are generally challenged because coal use makes a significant contribution to global man-made CO2 emissions. The drastic increase in the consumption of fossil fuels is not explained by the fact that coal utilisation technologies are not or cannot be sustainable but rather by the growing world population and the endeavours numerous national economies trying to catch up economically. Coal is the world’s No. 1 fuel and, in the view of many experts, will keep this position also in the foreseeable future. The access to its deposits plays a significant role for the economies of the emerging countries. Consequently the aspects of energy security and economic efficiency need to be considered at eye level with climate compatibility. In Germany, however, the public acceptance of fossil fuels and of large industrial projects is in the focus of attention.

Jan 1, 2011

As requested by my fellow members I shall endeavour to read a paper on the Treatment of the Auriferous Sulphide Ores of Kalgoorlie from a metallurgical standpoint. Before going into the subject it will be necessary for me to make some slight explanations. As most of you are aware many of our London friends holding interests in some of these mines think it necessary that their doings should be shrouded in mystery. The result of this is that in some cases it is impossible to get any official figures from the mines for this paper. I must ask you not to lose sight of the fact that in treating the sulphide ores of the Kalgoorlie mines we had absolutely no data to start on, and that to-day. we are just beginning to get a fair grip of tbe subject; and though very high extractions were announced when the first plants were started on sulphide ore, it was well known that this was only to maintain the public confidence in the mines to allow time to make necessary adjustments; and, as showing the advance made in the treatment of the ore, I notice several of the mines have published the results of the final or re-treatment of the residues of their first sulphide treatment. I have also had the opportunity afforded me of thoroughly sampling the residues of several of the principal mines, and find the results as now published absolutely correct.

Jan 1, 1901

By Michael Epstein, Daniel E. Rosner

Fume nucleation sufficiently close to vaporizing suvfaces can augment net vaporization rates into cooler environments. Environmental conditions favoring large vaporization rate enhancements are briefly discussed and a previous theoretical treatment of this nucleation phenomenon is generalized to account for the self-regulating effect of condensalion-heat release within the boundary layer. Despite kinetic limitations on homogeneous nucleation, and latent heat release, non-diffusive condensate removal processes appear to make possible large enhancements in steady-state vaporization rates, provided surface temperatures are well below the boiling point. When condensed phases vaporize (or dissolve) into cooler media, the diffusion-limited mass loss rate can be strongly influenced by the process of nucleation/con-densation (or precipitation) within the thermal boundary layer. This condensation process (which typically leads to mists or fumes in the case of evaporation into cooler gases) has the effect of steepening the vapor pressure profiles near the evaporating surface, since the condensation zone acts as a vapor sink. However. the resulting enhancement in the diffusion-limited evaporation rate can be estimated (as first done by Turkdogan1 for the case of molten iron/nickel alloys evaporating into helium) only if one has independent knowledge of the critical supersaturation, sCrit(T), required to homogeneously nucleate the vapor.* In a recent reformulation and generalization of the theoretical model of Ref. 1 it has been shown that, when log sCrit is approximately linear in reciprocal temperature, rather simple expressions can be derived4 for the ratio of the actual rate of vaporization j" to either the minimum (no condensation) rate j"min, or the maximum (equilibrium condensation) rate j"max In the present communication we wish to briefly report on further developments and implications of the formulation of Ref. 4, with emphasis on i) environmental conditions favoring large enhancements in vaporization rate, and ii) the self-regulatory influence of condensation heat release (neglected in Refs. 1 to 4) on predicted vaporization rates. Additionally, we take this opportunity to correct several misprints appear- ing in Ref. 4, and comment on Elenbaas's recent criticism5 of Ref. 1. MAXIMUM POSSIBLE VAPORIZATION RATE IN PRESENCE OF CONDENSATION A nonequilibrium theory is of interest because of the very large difference between the minimum (no condensation) and maximum (equilibrium condensation) vaporization rate. The magnitude of this maximum possible enhancement can be shown quite clearly by combining a result of Refs. 3 and 4 with the fact that for most liquids there is a simple relationship between the molar heat of evaporation, A, and its boiling point, i.e., A/(RTBp) = C, where the constant C, often called the Trouton ratio, takes on values not very different from 11.* More generally, for any substance (including The Trouton ratio (which for water is 13, for methane, 10, and so forth) will be recognized as the ratio of the molar entropy change upon vaporization (at TBP or Ttransf) to the unlversal gas constant R. Its near constancy reflects the fact that the change in atomic order upon vaporization depends only weakly on the kinds of molecules involved. those that sublime under ordinary conditions) we can define a characteristic transformation temperature. Ttransf, by a relation of the form Ttransf =A/(CR), and then examine the maximum possible evaporation rates as a function of how far removed from Ttransf are the surface temperature, Tw, and ambient temperature, T. Subject to the assumptions: 1) equilibrium vapor pressure, pv,eq, everywhere small compared to prevailing total pressure, p, and 2) negligible effect of condensation heat on temperature profile, the maximum enhancement ratio was found (Eq. [17], Ref. 4) to be: where, for most vapors, Nu/NuD (the ratio of heat transfer coefficient to mass transfer coefficient for the same configuration) is a number near unity.* Ex- *An alternative derivation of the Nu = NuD special case of this equation. revealing its validity for arbitrary velocity/temperature profiles in a laminar boundary layer, is given in Ref. 3. amining this result for a "Trouton substance", one obtains the results shown in Fig. 1, constructed for C = 11. Since we are concerned with vaporization enhancements (j'max/J"min > 1) at surface temperatures below Ttransf, this area of interest is shown unshaded. One notes that at a fixed ambient temperature (hence, T/TtranSf) there is a unique surface temperature, 2T , at which j"max/j"min attains its peak value; moreover, the peak enhancement ratio, see dashed locus. Fig. 1, is: (NuA/NuD)(C/4)(Ttransf/T,). Hence, if Nu = NuD, when the ambient temperature is less than 1/4 of TtranSf the peak enhancement exceeds the Trouton

Jan 1, 1969

By W. H. Smith

IN connection with some recent work on the effect of impurities on the ductility of chromium, it appeared desirable to know the solid solubility of carbon in chromium. A literature survey indicated that this information was not available. Although considerable work has been done on the Cr-C phase diagram,&apos;.&apos; previous investigators have been more concerned with the structure and phase boundaries of the carbide phases than with the terminal solid solution. The phase diagram shown in Fig. 1 is taken from the work of Bloom and Grant&apos; and represents the most recent determination. As indicated by the dashed line, the a solid-solubility limit was not determined. Experimental Procedure Alloys of chromium were prepared from hydrogen-treated and vacuum-degassed electrolytic chromium plus spectrographic grade carbon. The oxygen and nitrogen content of the alloys was <0.002 pct. After melting, analysis of the alloys showed them to contain 0.02, 0.08, 0.15, and 0.55 pct C. Pieces of the alloys were heated in a protective atmosphere to various temperatures and then quenched after holding for a time sufficient to insure equilibrium. Microscopic examination of the as-quenched alloys for the presence of a second phase was used as a measure of the solubility limit. The heats were made in a multiple hearth arc-furnace using a zirconium-gettered static argon atmosphere. A zirconium melt was made before each Cr-C heat. Triple melting was used to insure ingot homogeneity as shown by microscopic examination. The alloys were prepared by adding portions of a 4.5 pct C-Cr master alloy to high purity chromium. The carbon contents listed previously were those obtained by analysis. The nitrogen and oxygen contents after arc melting were both <0.002 pct. Sections 1/8X1/4X1/2 in. were cut from the 100-g ingots and a hole drilled in one end in order to suspend the sample from a molybdenum wire. After the surface was carefully cleaned, a sample of each melt was hung in a mullite tube heated externally by a platinum resistance furnace connected to a vacuum system. The lower portion of the mullite tube was sealed to Pyrex and closed off several inches below the furnace. This was filled with sili-cone oil kept cold by circulating cold water around the outside of the Pyrex. Quenching into the oil bath was achieved by melting a fuse wire supporting the sample. It required about 4 sec for the sample to cool from 1400" to 600°C. This severity of quench was considered satisfactory to freeze-in the high temperature equilibrium. For tests made at temperatures of 900" to 1200°C, heating was done in vacuum; for tests above 1200°C, an argon atmosphere was used. The holding time employed ranged from 12 hr at 900°C to 6 hr at 1400°C. Experiments were performed at temperatures of 900°, 1000°, 1100°, 1200°, 1300°, and 1400°C. Microscopic examination for evidence of a second phase was done at X1500. Experimental Result The microstructures of a 0.08 pct C-Cr alloy as-cast and after quenching from 1300°C are shown in Figs. 2 and 3. A 0.15 pct C-Cr alloy quenched from 1300°C is shown in Fig. 4. The data obtained from the quenching experiments is shown graphically in Fig. 5. If the Van&apos;t Hoff equation is obeyed, a plot on a logarithmic scale of the mol fraction of solute vs the reciprocal of the absolute temperature should give a straight line. For dilute solutions the weight percentage can be substituted for the mol fraction without introducing any appreciable error. The Van&apos;t Hoff equation can then be written as where H is the heat of solution in calories per mol. The slope of the straight line on the log pct C vs 1/T plot gives the value of AH. Assuming that the Van&apos;t Hoff equation is obeyed, which is probably justified for the dilute solution of carbon in chromium, the heavy straight line shown on Fig. 5 represents the best fit of the data. This line was obtained as follows. On Fig. 5 the results of the microscopic examination of all alloys following quenching were plotted and designated as to whether one or two phases were seen. Below 1100°C all alloys showed a second phase on quenching. The heavy vertical lines shown in Fig. 5 therefore represent the possible range of the ter-

Jan 1, 1958

By S. A. Lever, R. Hultgren

The solidus is usually the least satisfactorily determined portion of a phase diagram. Cooling curves, which succeed well with the liquidus, show the solidus inaccurately or not at all because of segregation which occurs during freezing. Heating curves of carefully homogenized alloys might be expected to indicate accurately the solidus, but they are seldom used. Dynamic methods involving heating or cooling are never completely satisfactory because of uncertainty as to whether equilibrium is attained. A static method in which the specimen may be allowed hours, days, or even weeks to attain equilibrium is to be preferred. In a static method a solid solution, for example, is first made thoroughly homogeneous, then heated to successively higher temperatures. After sufficient time at each temperature to assure equilibrium, some property is measured which should alter strikingly when melting begins. Microscopic examination can be used to detect the beginning of melting, but the method is tedious since the specimen must be quenched, sectioned, polished, and etched before each examination. Of all the physical properties which change on melting, electrical resistance is probably the most satisfactory to measure. The measurement may be made while the specimen is at temperature without damage to the specimen. It may be repeated indefinitely to ascertain when equilibrium has been achieved. Measurements may be made on a single specimen over the whole range of temperature. Most metals approximately double their resistance on melting. Since an accuracy of a few tenths of a percent is easy to achieve, the method is highly sensitive to the beginning of melting. In spite of these advantages, which have been perceived for a long time,l,2 a reasonable search of the literature has failed to reveal a single case in which the method has been satisfactorily applied in practice to the determination of solidus temperatures. The use of electrical resistance measurements appears to have been confined in practice to changes in the solid state. In the work described in the following pages we have applied the electrical resistance method to the solidus of the lead-tin system. We have found the method to be convenient, reproducible, and highly sensitive. We chose the lead-tin system because it leads to few technical difficulties. Furthermore, a number of determinations of solidus have been made in this system by various methods and results could be checked against them. However, all published results are not in good agreement with one another, so this work should help in determining the solidus more precisely. The Lead-tin Diagram Because of its commercial importance, there have been numerous investigations of the lead-tin diagram. The results of the most recent work on the solidus are indicated in Fig 7, as well as the results of the present work. The works of Honda and Abe3 and of Stockdale4 agree fairly well with each other and with the present work. Jeffery&apos;s5 data indicate the solidus to be about 50°C lower. Honda and Abe3 used differential thermal analysis on both heating and cooling cycles. Stockdale4 used the microscopic method and also differential heating curves. Stockdale&apos;s results were about 4" higher than those of Honda and Abe at low tin contents and lower at higher tin contents. These results also agree with those of Rosen-hain and Tucker.= Jeffery5 used electrical resistance measurements of the alloy as it was being heated or cooled. Apparently he did not attain equilibrium as his results are about 40°C lower than those of Stockdale4 or Honda and Abe.3 MATERIALS AND METHODS The lead and tin used were of high purity. They were supplied by the American Smelting and Refining Co., who gave the following analyses: Lead: silver, 0.0016 oz per ton; copper, 0.0008 pct; cadmium, 0.0007 pct; zinc, 0.0002 pct; arsenic, 0.0003 pct; antimony, 0.0002 pct; bismuth, 0.0005 pct; tin, 0.0001 pct; iron, 0.0020 pct; lead (by difference), 99.995 pct. Tin: antimony, 0.037 pct; arsenic, 0.020 pct; bismuth, 0.004 pct; cadmium, trace; copper, 0.025 pct; iron, 0.004 pct; lead, 0.020 pct; nickel and cobalt, 0.005 pct; silver, 0.0005 pct; sulphur, 0.005 pct; tin (by .-difference). 99.88 pct. One hundred grams of metal with the desired proportions of lead and tin was weighed out to the nearest one-tenth of a milligram. The mixture was placed in a silica crucible, covered with charcoal, and melted in a reducing atmosphere in a gas-fired furnace. The alloy was well stirred. Chemical analysis of two of the alloys checked closely with the weighed portions. The compositions of the remainder of the alloys were taken directly from the weighings, without chemical analysis.

Jan 1, 1950

By F. M. d’Heurle

Films of molybdenum have been prepared by sputtering onto oxidized silicon substrates. The resistivity. lattice parameter, orientation, and grain size were studied as a function of substrate temperature and substrate bias. Under normal sputtering conditions, the resistivity of the films was found to be quite high (600 x 10 ohm-crn). However, with the use of the negative substrate bias of 100 v and a substrate temperature of 350°C, films weve produced with a resistivity of ahout twice that of bulk molybdenum. The lattice parameters measured in a direction nornzal to the surface of the films weve found to be gveatev than the bulk value. This was interpreted as being at least partly due to the presence of compressive stresses. The effects of annealing in an Ar-H atmosphere were studied in terms of diffraction line width, lattice parameter, and resistivity. BECAUSE of its relatively low bulk resistivity (5.6 x 106 ohm-cm)&apos; molybdenum is potentially interesting as a thin-film conductor in integrated circuits. An additional feature which makes it attractive for this purpose is its low coefficient of expansion (5.6 x KT6 per "c),&apos; which is fairly well matched to that of silicon (3.2 x 10 per c). It is possible to deposit molybdenum films by evaporation but generally films produced in this manner have a high resistivity. In order to achieve resistivities close to bulk value, Holmwood and Glang found it necessary to operate in a vacuum of about 107 Torr and to maintain the substrates at 600 C during film deposition. Sputtered molybdenum films have been examined by Belser et a1.7 and, recently, by Glang et al.&apos; This paper describes the results of an attempt to extend some of that work and examine the effects of annealing and getter sputtering on the physical and structural properties of the films produced. SPUTTERING APPARATUS AND PROCEDURE The apparatus used for most of the film sputtering work described here consisted of two "fingers" serving as anode and cathode, respectively, which were mounted within an 18-in.-diam glass chamber. A liquid nitrogen-trapped 6-in. diffusion-pump system was used to achieve a vacuum of about 1 x 107 Torr within the chamber prior to sputtering. The essential features of the equipment are shown in Fig. 1. Cathode and anode fingers are stainless-steel tubes isolated from the top and bottom plates by Teflon collars. In order to limit the discharge to the space between anode and cathode, each finger is surrounded by an aluminum hield, at ground potential, having an internal diameter 18 in. larger than the outside diameter of the finger. The cathode and anode fingers are 6 and 4 in. in diam, respectively. A 116-in.-thick sheet of molybdenum is brazed with a 10 pct Pd, 58 pct Ag, 32 pct Cu alloy to a copper disc which is mounted by means of screws and a large 0 ring onto the lower end of the cathode finger. The disc is cooled during sputtering by water circulation inside the finger. The use of several feet of plastic tubing for the water input and outputg reduces leakage to ground to less than 1 ma when the cathode potential is raised to 5 kv. The upper end of the anode finger is terminated by a brazed-on copper block. A variety of specimen holders can be easily mounted on the upper face of this block. Substrate heating or cooling is achieved by use of an appropriate unit attached to the lower face of the same block. Heating is achieved by means of cartridge-type heaters and cooling by copper coils fed with forming gas under pressure. The inner chamber of the specimen finger constitutes a small vacuum chamber of its own which is evacuated by an auxiliary mechanical pump in order to limit heating element oxidation and heat transfer by convection currents. An advantage of the finger arrangement is the absence of cooling and heating coils and wires within the main chamber. The stain less-steel shutter is useful to establish a discharge for cleaning the cathode at the beginning of each sputtering run. Water cooling of the shutter reduces heating and the out-gassing of impurities which might condense on the nearby substrates. Unless otherwise specified, the substrates used in these experiments were 1-in.-diam oxidized silicon wafe:s, 0.007 in. thick, having an oxide thickness of 6000A. The substrate holders were large copper discs onto the surface of which a number of molybdenum discs, 116 in. thick and 78 in. in diam, were brazed. The wafers were clamped to the molybdenum discs

Jan 1, 1967

By H. W. Meyer, H. N. Lander, F. D. Delve

A method of calculating the changes in blast-furnace performance brought about by burden and/or blast modifications is presented. Essentially the method consists of three simultaneous equutions derived from materials and heat balances. These equations can be used not only to evaluate quantitatively the effect of changes in process operating variables on furnace performance, but also to provide a useful means of evaluating changes in process variables which cannot be measured directly. It has been customary for a number of years to use simple heat and materials balances as a basis for assessing blast-furnace practice. A good example of the method used to set up these balances is that proposed by Joseph and Neustatter.1 This approach to process assessment has limited utility, however, in that it cannot be used to predict the furnace coke rate or production under new operating conditions. Using an approach based on multiple correlation of blast-furnace variables, R V. Flint2 has developed an equation which may be used to predict the change in coke rate that will result from some changes in operating conditions with a reasonable degree of accuracy. Although this equation has useful applications in production planning, it cannot be used to study the relationships between the operating variables and the fundamental thermochemi-cal characteristics of the process. In attempting to analyze the blast-furnace process quantitatively, the idea of dividing the furnace into zones3 may at first appear attractive. In our present state of knowledge, however, it is not possible to define with any accuracy the physical limits of such zones in relationship to their temperatures or to the reactions which may occur in them. Although its application is restricted, the zonal approach to blast-furnace analysis is useful in some instances. For example, the change in the calculated flame temperature in the "combustion zone" caused by injecting steam constitutes information which is helpful in understanding why the addition of steam to the blast is best accompanied by an increase in blast temperature. The zonal approach cannot, at the present time, be used to establish the relationships between process variables and process performance if the whole process rather than part of it is to be considered. One of the earliest approaches to the problem of relating blast-furnace operating variables to pro- duction and coke rate was that developed by Marshall.4 Essentially Marshall&apos;s work showed that it was possible to estimate the performance of a furnace by solving three simultaneous equations which consisted of rudimentary carbon and heat balances plus a further equation relating the production, wind rate, and the carbon burned at the tuyeres. Although these equations did not include all of the chemical and thermal variables of the process, their derivation and application seems to be the earliest attempt which achieved any success in relating prior furnace operating data to the calculation of furnace performance under different blast conditions. Work carried out in Germany has been directed mainly towards prediction of coke rates using material and thermal balances rather than statistical methods. wesemann5 used prior furnace operating data as part of the basis for predicting the change in coke rate accompanying a change in burden composition. This author employed a method of successive approximations to estimate the secondary changes in slag volume and stone rate brought about by the change in coke rate. The most recent analysis, which seems to have been developed concurrently with the thermochemical model presented in this paper, has been described by Georgen.6 This author has succeeded in improving on Wesemann&apos;s approach by expressing the total changes in the slag volume and stone rate in terms of the change in coke rate itself. This is accomplished in a manner similar to that used in the thermochemical model described in this paper. Although Georgen makes use of a calculated furnace heat loss, he does not relate the heat loss per unit of hot metal to the production rate as is done in the present work. Georgen&apos;s approach may be used to calculate the changes in materials requirements accompanying changes in furnace operation; it cannot be used to assess the resulting changes in production. The fact that blast-furnace behavior can be interpreted by consideration of the heat requirements of the process was demonstrated by Dancy, Sadler, and Lander.7 In the analysis of blast-furnace operation with oxygen and steam injection these authors showed that it was possible to account for the changes in production and coke rate

Jan 1, 1962

By Sheridan J. Rodgers

Toxic fumes generated during shot firing under actual mining conditions were measured. Eight shots with Gelodyn-2X and seven shots with Tovex-100 4VT were monitored. Average CO values for Gelodyn-2X and Tovex-100 4VT were 0.20 ft3/lb and 0.09 ft3/lb, respectively. Average N0x values for Gelodyn-2X and Tovex-100 4VT were 0.049 ft3/lb and 0.026 ft3/lb, respectively. The results obtained with these in-mine tests will be used by the U.S. Bureau of Mines in the development of a large chamber method of measuring fumes from shotfiring of explosives.

Jan 1, 1977

Although bismuth mineralization is spread widely through the Lachlan Fold Belt in New South Wales, broad grouping of the various deposits can be effected on the basis of geographical and geological (age and type of associated rocks) affinities. As a result, significant concentrations of bismuth can be recognized in the Mid-Western granites, Cobar-type ore, the Yass Silurian acid volcanic belt, and the Albury, Bega, Braidwoodand Bathurst districts.In these deposits bismuth generally occurs in minor amounts associated with molybdenite, wolframite, scheelite, cassiterite, chalcopyrite, galena, magnetite, pyrite, arsenopyrite, and native gold. From this group of minerals three broadly defined associations can be recognized.I. Bi-Sn-W-Mo2. Bi-Au( -Te)3. Bi-Pb-Cu(-Au)There may be some interchangeability of these metals, as instanced by occasional Bi-Cu-W-Mo mirleralization, but pyrite and/ or arsenopyrite are usually prominent in all associations.The first two of these associations occur mainly in the form of narrow quartz veins rarely averaging more than O&#183; 3 per cent Bi, although there is often a marked enrichment in ferruginous material in the oxidized zone.Most of these veins occur within or adjacent to granitic rocks of varying ages (principally Silurian or Devonian), although Bi-Au mineralization tends to be related to more basic igneous activity than the Bi-Sn-W-Mo association.The latter is also occasionally developed in pipes, usually coarse-grained and richer in bismuth (as at Whipstick, the principal mine in New South Wales with a production of 343 tonnes of the metal), or in lower grade, but probably larger tonnage skarn deposits. The bismuth-base metal association occurs mainly in Silurian acid volcanic sequences and may also form low grade but large tonnage deposits, such as is possibly developed at Cobar.

Jan 1, 1973

By Ramón Sánchez, T. López Willy, M. López Willy

La exploración de depósitos de Zn supergénicos conlleva la necesidad de poder evaluar la concentración de este metal base en campo, donde el uso de la técnica de tinción “Zinc Zap” se vuelve fundamental. La evaluación de un rango amplio de muestras de sondaje diamantino y rechazo fino (pulpa) utilizando la mencionada técnica ha dado la posibilidad de categorizar tres grupos principales según coloración, dependiendo de las concentraciones de Zn: 0.5 - 2.0 % con RBG (150,121,97); 2.1 - 8.0 % Zn con RGB (114,52,32); y ˃8.1% Zn con RGB (83,37,45).

May 10, 2023