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By T. K. Perkins, L. R. Kern, R. E. Wyant

Many factors influence the results of hydraulic fracturing to stimulate well productivity. Most of these factors have been studied and their effects discussed in the literature. However, the movement of sand through the crack during fracturing has received little consideration. Exactly where the sand goes in the fracture, how it gets there, and how this might influence results have not been studied, judging from published reports. To get an answer to some of these questions we have studied sand movement through a simulated crack segment in the laboratory. Although the work is preliminary, we have answered some questions about sand movement in a semiquantitative sense. We are reporting our results at this time in the hope of stimulating interest and further study in this important aspect of fracturing. LABORATORY EXPERIMENTS Fig. 1 is a schematic diagram of equipment used in this study. A segment of a vertical crack 0.25-in. wide was formed between two Plexiglas plates, and movement of sand in fluid through the crack was observed under various conditions. Sand and fluid were injected into the crack at constant rates. The top and bottom of the crack were closed so that the fluid flowed horizontally. Because of gravity most of the sand settled to the bottom before moving very far through the crack. If the fluid velocity exceeded a certain critical value, then all the sand injected was washed on through the crack even though it had settled to the bottom. When the fluid velocity was less than this value when sand injection was started, most of the sand which settled in the crack remained in place until enough of the area open to fluid flow was blocked by the settled sand to increase the fluid velocity to the critical value.. At this point all injected sand moved on through the crack even though it settled to the lower portion of the moving fluid section. All sand previously settled remained in place. When fluid velocity was increased at this paint by increasing fluid injection rate (without also increasing sand injection rate), some of the previously settled sand was washed out until enough area was open to flow that the velocity dropped to the critical value. Conversely, when the fluid velocity was decreased by decreasing the fluid injection rate (without changing the rate of sand injection), additional sand would settle until the critical velocity was again attained. In short, the critical velocity is an equilibrium value which the system will automatically seek, if possible. The equilibrium (or critical) velocity was measured under several conditions. The results of these measurements are shown in Pig. 2 where the equilibrium velocity is shown as a function of the amount of sand injected per minute. The points falling in the shaded band shown in Fig. 2 were obtained with water. The higher viscosities were obtained by adding CMC (carboxymethylcellu-lose). Data indicate that the equilibrium velocity is not very sensitive to sand size or transport fluid viscosity, or to sand injection rate (except at very low rates). Points connected by the solid CUrve in Fig. 2 were obtained with water and 20- to 40-mesh steel shot. The equilibrium velocity is apparently fairly sensitive to difference in density between particle and fluid. Only one run was made with a gelled fluid and that was gelled water at zero sand injection rate as shown in Fig. 2. (Measurements of equilibrium velocity at zero sand injection rate were made by filling the crack

By P. Choquet, F. Miller

"The development and testing of a simple low-cost gauge for measurement of tension in a cable bolt grouted in a borehole are presented. Its principle is based on a resistance wire which is wound on a 70 cm length into the spiral grooves of the wire strand cable bolt. Readings are then taken by a robust automatic data logger with a several day autonomy or by a portable readout. In order to have a complete profile of tension along the cable bolt, a number of tension gauges can be installed along its length.This paper provides a description of the development and laboratory calibration of the tension gauge and addresses the two modes of loading for a cable bolt in a rock mass, namely pure tension and shearing at a joint location.In the second part of the paper, four field tests in underground and open pit mines are reported. The first test was used to substantially modify both the gauge and the readout unit principles while the other tests which are still on-going show a very satisfactory behaviour of the modified version of the tension gauge. IntroductionCable-bolting is often used as ground support in Canadian mines for a variety of applications. In underground mines, cable bolts can be installed vertically at the back of cut and fill stopes or in an inclined fashion in the walls of large open stopes. Alternatively, cable bolts at Mines Gaspe (Noranda Inc.) are used in a fan-shaped pattern from a drill drift to stabilize the inclined roof in 25 m wide open stapes. This new application oriented our research efforts toward the design of a novel instrumentation to monitor the efficiency of most commonly used 5/8-inch cable bolts."

Jan 1, 1988

By A Priatna, H Rumbino, T Casten

This paper discusses the progress of the Deep Mill Level Zone (DMLZ) mine from the pre-feasibility study completed in 2005, through commencement of development access in 2008, completion of the feasibility in 2010 and cave initiation in late 2015. This fourth lift of caving in the East Ertsberg Skarn System (EESS) is located 500 m below the currently producing Deep Ore Zone (DOZ) mine and represents approximately half a billion tonnes of ore and around 1900 planned drawpoints, scheduled to be mined at a peak of 80 000 t/d.The paper reviews the mine design, access requirements, planned footprint sequence and major fixed facility installations such as ventilation, oreflow and shops. A discussion of the preproduction development and construction activities and some of the critical technical challenges overcome during this time frame are addressed, as well as the cave initiation process undertaken in late 2015 and the ramp-up of production and progression of caving.CITATION:Casten, T, Priatna, A and Rumbino, H, 2016. Deep Mill Level Zone – from feasibility to production, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 635–644 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

By P. J. Closmann

Steam zone growth as a function of time has been calculated for the case of constant rate steam injection into a preheated reservoir. To simplify the calculation a linear temperature profile has been assumed in the cap and base rock at the start of steam injection. The results indicate that at early times augmentation of steam zone growth due to preheating should be greatest. At longer times the steam zone development becomes close to that calculated with no preheating. INTRODUCTION With the increasing application of thermal recovery processes to recover viscous oil, cyclic steam injection has become important in many large-scale projects. In this process, the cycle of steam injection followed by oil production is repeated a number of times. At the beginning of the second and later cycles, steam is injected into a reservoir that has already been heated but that has lost part of its heat both in produced fluids and by conductive heat loss away from the injection zone. In such a case, the temperature level of the injection zone and the temperature distribution of the surrounding rock will affect the growth of the steam zone developed during the subsequent steam injection. Knowledge of the size of steam zone developed is important in determining the amount of oil displaced and the extent of heating in the reservoir. It is also useful to be able to compute the size of the steam zone for cases where thief zones take most of the injected steam. This paper presents a fairly straightforward method of estimating the steam zone developed in a preheated formation, based on certain simplifying assumptions. Some cases of steam injection into a reservoir at its original temperature have already been considered elsewhere.1-3 Because it is difficult or impossible to obtain an accurate representation of the temperature distribution in the reservoir some time after initial heating has taken place, in this work, a linear temperature profile in the cap and base rock is assumed (Figs. 1A and 1B). The linear profile has the advantage of yielding heat flow equations that

Jan 1, 1969

By E Villaescusa, C Drover

Fully resin encapsulated threaded bar and cement grouted cable bolts are common forms of reinforcement for underground mining excavations constructed at great depth. These elements are frequently installed to dissipate the dynamic loads caused by violent rock mass failure mechanisms. Failure of the ground support scheme without rupture of the reinforcement elements implies that the maximum energy dissipation capacity of the scheme was not utilised. The ground support damage mechanisms are useful to identify in this context as they reveal vulnerabilities which limit the scheme performance. This paper presents a number of field observations of reinforcement performance following a range of dynamic loading conditions. It was observed that fully resin encapsulated threaded bars exhibit variable behaviour. In particular, inconsistent resin encapsulation was frequently observed in combination with surface support failure, indicating that the retention function of these elements may allow preferential loading of the surface support system. Observations of cement grouted, twin-strand plain cable bolts reveal a common mode of damage involving differential displacement across the steel-grout interface and slip of the cable within the borehole. This is common where strands are not mutually tensioned with barrel and wedge assemblies. Surface fixtures that exceed the strength capacity of the cable strand are required in order to minimise the occurrence of this response. Improved load transfer from the rock mass and surface support to the cable can thus be achieved, particularly where small block size failure occurs.CITATION:Drover, C and Villaescusa, E, 2016. Field performance of fully encapsulated reinforcement during violent failure events, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 659–668 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

Biosorption of Cr(VI), Pb(II) and Zn(II) from Aqueous Solutions by Immobilised Phanerochaete chrysosporium Biomass in a Fixed-Bed Column The continuous-flow adsorption of Cr(VI), Pb(II) and Zn(II) from aqueous solution by immobilised Phanerochaete chrysosporium biomass in a fixed-bed column was studied. The effects of flow rate, influent concentration of Cr(VI), Pb(II) and Zn(II) and bed depth on breakthrough curves and biosorption capacity were investigated. The experimental results showed that the breakthrough time decreased with increasing flow rate, increasing influent concentration and decreasing bed depth. The data also indicated that the equilibrium uptake of Cr(VI), Pb(II) and Zn(II) increased with decreasing flow rate and increasing influent concentration of Cr(VI), Pb(II) and Zn(II). Two models were employed to predict the breakthrough curves and to determine the characteristic parameters of the column useful for column design. The Thomas model was able to predict the breakthrough curve in the range of relative concentration(Co/Ci) higher than0.3, Cr(VI), Pb(II) and Zn(II) whereas the validity of the Bohart-Admas model was limited to the initial part of breakthrough curve at all flow rates and influent concentrations of Cr(VI), Pb(II) and Zn(II). The feasibility of reusing the immobilised fungal beads through five adsorption/desorption cycles in fixed-bed column was investigated.

Sep 13, 2010

By R. A. Harris

In this study Pt-Al thin films were prepared via electron beam physical vapour deposition (EB-PVD) with an atomic concentration ratio of Pt25:Al75. These films were heat treated at temperatures ranging from 150°C to 650°C for annealing times from 4 to 60 minutes. The resulting microstructure of these thin films were obtained via secondary electron imaging used in conjunction with depth profiling with the aid of scanning auger microscopy (PHI 700).Elemental maps of the micrographs were obtained. Simulations, based on a chemical potential Monte Carlo method1, were run for various interaction parameters. From these simulations theoretical depth-profiles and proposed microstructures were obtained. These were compared to the experimentally measured depth profiles and elemental maps. Keywords Monte Carlo, chemical potential, depth profile, Pt-Al thin films.

Jan 1, 2011

By Vernon K. Garrett, Gerhard Sauer

INTRODUCTION Generations of tunneling engineers had to fight not only against bursting rock and squeezing ground but also against the destroying power of water. Intrusion of groundwater into the tunnel opening affects the stability of the tunnel support system, reduces the safety of the traffic inside the tunnel, induces corrosion of installed equipment, and provides for creeping currents at electric facilities. Aware of these problems, engineers of the Washington Metropolitan Area Transit Authority and their consultants opened the way for a new approach in sealing a tunnel. It was made possible by accepting a new method of tunnel construction scarcely applied in the U.S. before. This new technique, the New Austrian Tunneling Method (NATM), provided the basis for the successful installation of a PVC-membrane between two separated shells of tunnel lining, and the carefully directed drainage of groundwater. Beside of the economic benefits already attained by applying the NATM for tunnel construction, the Authority now saves millions of dollars otherwise necessary to maintain the tunnel during its lifetime (Garrett, 1986; Setzer, 1986). But there is a large number of leaking tunnels built according to conventional methods, some of them facing severe problems jeopardizing the safe utilization of these structures. Recently developed methods indicate that even those tunnels can be rehabilitated without extensive costs by draining and sealing them afterwards. A road tunnel in the Austrian Alps provides the scene for a major attempt to convert one of those leaking tunnels into a dry structure.

Jan 1, 1987

By S. Y. Chen

A new process comprising metallizing reduction, magnetic separation, and electroheat melting separation is proposed with the aim of achieving high recoveries of iron, vanadium, and titanium from vanadium titanomagnetite. The effects of magnetic intensity, reduction temperature, reduction time, carbon ratio, and coal particle size on the efficiency of reductionmagnetic separation were investigated, the reaction mechanisms elucidated by SEM and EDS analysis, and the optimal process parameters established. Recoveries of up to 80.08% for titanium, 95.07% for iron, and 71.60% for vanadium were achieved. The reduction sequence is shown to be: Fe2O3 ? Fe3O4 ? FeO ? Fe; Fe2TiO5 ? Fe2TiO4 + TiO2 ? Fe + FeTiO3 ? Fe + FeTi2O5 ? Fe + TiO2.

Jan 1, 2014

By A N. Kasnanto, D A. Sims, J Pocoe, B Pulungan

In this case study we compare the sampling quality of diamond drilling (DD) and reverse circulation (RC) drilling at the high sulfidation Purnama gold–silver (Au-Ag) deposit located in northern Sumatra, Indonesia.There was a systematic bias of 23 per cent gold metal under-call in the diamond drilling based Ore Reserve estimate compared to the mill reconciliation over three years of production. The RC based Grade Control data and mill production data were in much closer accord. Investigation led to quantification of the significantly reduced sampling imprecision (or improved precision) of RC drilling samples relative to diamond drilling samples and the determination of a grade bias between the drill types caused by sample volume and metal distribution in the mineralisation. An infill RC drilling program was undertaken to improve data density across the pit for inclusion in the Mineral Resource estimate. This subsequently increased Au metal in the estimate by 16 per cent.The sampling imprecision of primary diamond drill sampling is rarely tested. Duplicate sampling can be used to quantify sampling imprecision at each stage of subsampling. In diamond drilling it is tested at the primary sampling stage via second half core sampling, while RC sampling is tested with field duplicate sampling at the rig. Duplicate data can be compared in a number of ways to determine imprecision including Thompson-Howarth plots which quantify imprecision to allow comparison between different methods and protocols. Comparing sampling imprecision between data sets and data types allows determination of optimum drilling and sampling protocols and can reflect upon the underlying validity of Mineral Resource input data and estimation outputs.CITATION:Sims, D A, Pocoe, J, Kasnanto, A N and Pulungan, B, 2017. Why combine reverse circulation and diamond drilling in Mineral Resource estimation at Purnama?, in Proceedings Tenth International Mining Geology Conference 2017, pp 413–422 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 20, 2017

By C. Sun

The Leeville underground mine has been in operation since 2006 and currently produces 3,200 tons of ore per day with an average gold grade of 0.4 opt. The mine has a large horizontal extent of 2,500 feet by 500 feet and a vertical extent of 20 to 200 feet. High density of joints occurs within the host rock. Based on Rock Mass Rating and field observation, the Leeville ground conditions are characterized as poor to very poor. As such, heavy ground support is required for the mining operation in Leeville. Ore zones with a height in excess of 10 m (35 feet) are considered for longhole stoping. A typical stope measures 6.0 m (20 feet) wide, 30 to 55 m (100 to 180 feet, depending on the ground conditions) long and 10 to 30 m (35 to 100 feet, depending the thickness of ore body) high, yielding 10,000 to 20,000 tons when completed. Narrow ore zones, less than 10 m (35 feet), are mined using cut and fill. These drifts are 4.6 m (15 feet) wide by 4.6 m (15 feet) high. Based on the afore-mentioned poor ground condition, the establishment of a ground control monitoring system is key to operating both safely and successfully. The ground control monitoring system is composed of comprehensive instrument design and installation. Instruments include Multi-Point Borehole eXtensometers (MPBX) and Stretch Measurement to Assess Reinforcement Tension (SMART) cables. The monitoring system covers the mining zones and infrastructure openings. After about two year?s applications and measurements, useful data has been and continues to be collected to use in future stope and infrastructure structure design. The system provides the information making engineer and operation teams to do their job more confident and efficiency. Keywords: Ground control, Monitoring system, Long hole stope, Instrumentation.

Jan 1, 2009

By R. Lahtinen, M. Tiainen, R. Salminen

The application of similarity analysis derived from regional geochemical mapping data to the location of Ni-bearing intrusions was tested in southwest Finland, where a well-known nickel belt is situated. Samples of till from the vicinity of the Vammala and Kylmakoski Ni-Cu deposits, which were collected independently of the Geological Survey of Finland's regional geochemical mapping programme, were used to provide geochemical modelling data. The data consist of the aqua regia-leachable concentrations of 20 elements from the less than 0.06-mm fraction of glacial till. The variables used in the similarity analysis were selected on the basis of a factor analysis in which the method of oblique rotation was used. A hierarchical clustering of the modelling samples produced two main groups. The first group was described as the "nickel deposit environment model" and the second as the "nickel deposit location model". The data for the standardised variables were compared sample by sample with the model data by similarity analysis using the Simana program with a cos theta measure of pattern similarity. The nickel deposit environment model delineated the known Ni belt and indicated an extension to the east. The nickel deposit location model identified target areas of reasonable size with the greatest potential for Ni ores within the nickel belt

Dec 1, 1991

By D Craw, D Falconer

The Morning Star mine is one of numerous historically mined gold-quartz lodes in the Preservation Inlet goldfield of southwest Fiordland. The mine is hosted in Early Ordovician metasedimentary rocks that are composed predominantly of psammitic and pelitic lithologies. These rocks still contain their primary depositional features and are characterised by upper greenschist facies metamorphic grade.   The Morning Star mine lies on the eastern limb of a gently south plunging anticline. A bedding parallel fault-vein and an associated network of minor quartz veins hosts mineralisation. The main fault-vein structure strikes N-NW, dips steeply (~60¦) W, has a strike length of ~350 m, a vertical extent of ~170 m and is up to 2 m in thickness. The internal structure of the fault-vein consists of laminated quartz, massive and fibrous quartz, and silicified breccias/cataclasites. Gold is typically coarse grained (~1 - 2 mm) and associated with pyrite, arsenopyrite, chalcopyrite, tetrahedrite and galena. The geometry of the Morning Star mine is similar in form to that of a saddle reef. Gold-quartz lodes in the Preservation Inlet goldfield are comparable in geometry and host rock to their offset equivalents in the Golden Blocks field of NW Nelson.

Jan 1, 2005

NASA has received direction for lunar habitation beginning in 2024. Prior to then, it will be necessary to learn about how lunar soil can be used to promote civilization on the moon. Questions must be answered: ?Will it support plant life?,? ?Can it be used as a construction material?,? ?What is needed to maximize health and safety?,? and ?Will it affect equipment, tools, machinery, and clothes?? The only samples available for study came from the Apollo Missions. Because the expense of bringing more material back to Earth is prohibitive, there is not enough available to perform studies to answer the above questions. Hence, there is a great need for its synthesis. Most efforts to date have concentrated on making ?simulant? from single natural resources of volcanic rock. However, another possibility is to use resources here on Earth to extract the minerals of interest into concentrates or so-called ?separates? using traditional mineral processing techniques, and then mix the separates in appropriate ratios to simulate the lunar soil. In this paper, results from a study in which dry Road Norite outcrop and wet mill tailings from the Stillwater Mining Company?s Concentrator located near Nye, MT were examined. Of course, the in-side challenge is to make ?separates? from gangue minerals.

Jan 1, 2012

By Denis Labrie

Le minage en profondeur sous contrainte modérée à élevée présente de nombreux défis aux opérateurs et aux ingénieurs de mine notamment au niveau du contrôle de terrain et de l?environnement minier souterrain, pour assurer la sécurité des travailleurs sous terre et la continuité du cycle d?opération. Des conditions de contrainte élevée signifient une pression accrue au front de taille et sur les structures minières tels les piliers de mine et les fins de zone, un risque de rupture violente ou de coup de toit plus élevé, des zones de rupture plus grandes au pourtour des excavations, des charges accrues sur le support de terrain, etc. Le présent article fournit un aperçu du travail fait à l?intérieur du Programme de Contrôle de terrain de CANMET au cours des sept (7) dernières années, entre 1995 et 2001, pour comprendre et suivre l?évolution des niveaux de contrainte à l?intérieur des structures minières. Les propriétés déterminées en laboratoire sur des échantillons rocheux et les prévisions effectuées au moment de la conception sont comparées avec les observations effectuées en chantier à la paroi des excavations et à l?intérieur de la masse rocheuse. La plupart des cas discutés ici montrent une corrélation satisfaisante entre les observations effectuées en chantier d?une part, et les résultats d?essai obtenus en laboratoire et les calculs réalisés lors de la conception d?autre part. Ces observations peuvent donc être considérées comme des moyens relativement sûrs pour vérifier et suivre l?évolution des niveaux de contrainte présents à l?intérieur des structures minières.

May 1, 2002

By B. Valentim

The methodology used to obtain fly ash subsamples of different sizes is generally based on wet or dry sieving methods. However, the worth of such methods is not certain if the methodology applied is not mentioned in the analytical procedure. After performing a fly ash mechanical dry sieving, the authors compared those results with the ones obtained by laser diffraction on the same samples and found unacceptable discrepancies. A preliminary study of a wet sieving analysis carried out on an economizer fly ash sample showed that this method was more effective than the dry sieving. The importance of standardizing the way samples are handled, pretreated and presented to the instrument of analysis are suggested and interlaboratory reproducibility trials are needed to create a common standard methodology to obtain large amounts of fly ash size fraction subsamples.

Jan 1, 2008

By L. F. Elkins

Water coming into wells with bottom water present in the Fosterton field, when their oil recovery was only 0.1 to 1.5 per cent of oil in place below the lowest perforation, confirms lack of shale barriers to vertical flow which also are not apparent in cores and electric logy. Low contrast of vertical and horizontal permeability, high mobility ratio betweerz oil and water zone and pos.rible rate effects due to gravity Combine to prevent easy analysis of water invasion pattern and efficiency by analogy or intuition. Theoretical analysis of performance including these factors using a new direct nurnerical .solution of potential distribution in a network led to unanticapted indications that water would under-run the entire oil reservoir with low volumetric coverage if supplied through natural influx or peripheral water injecfion below the oil-water contact. An unusual pattern of water injection is to he adopted in this recently unitized pool to provide more uniform water flooding in that two-thirds of the oil reservoir not underlain by bottom wafer. INTRODUCTION The Fosterton field, Southwestern Saskatchewan, Canada, was discovered in Jan., 1952. It produces at a depth of 3,100 ft from a pinch-out of the Roseray sand at the Lower Cretaceous-Jurassic unconformity. The field, covering 2,500 acres, contains 54 wells on 40-acre spacing. Development was essentially complete in June, 1954, but significant production did not start until May, 1955, when a pipeline outlet became available. Within one year rapid in- creases in gas-oil ratio and early encroachment of water created operating problems in the down-structure eastern half of the field and raised serious questions about reservoir performance and ultimate recovery. This paper describes the unusual behavior of water encroachment—on both well and reservoir bases—and the analyses made to interpret it. The field was unitized July 1, 1958, for water flooding. A somewhat unconventional

By Robinson KJ

There has been much debate in recent years regarding the number of Geology (Earth Science) graduates produced in Australia. The key variable has commonly been assumed to be the placement of graduates in the mineral and petroleum industries. Although not wishing to deny the importance of this element, we contend that Geoscience studies should be given to a wider variety of graduates. The essence is to make students and future citizens more environmentally aware. INTRODUCTION Geoscience is fundamental to exploration and to the well-being of the minerals industry and hence the Australian economy. The value of mineral primary products exports for the past three years has been: 1895 $15.3 billion 1986 $14.8 billion 1987 $16.3 billion (Data source: B.M.R) The mining industry supplies about 40% of Australia's export earnings. However the overall value of Geoscience to the Australian economy is much greater. At the opening of the ANZAAS conference in Townsville during May 1987, Sir Bruce Watson , Chairman of the Mt. Isa Mines Ltd., made a plea for a national re-examination of the way science is taught in secondary schools. In particular he emphasized the point that the community should be more aware of the importance of Geoscience and the value of the mining industry to Australia.

Jan 1, 1989

By R. H. Atkinson, R. N. Rhoda

An improved technique has been developed for the deoxidation of palladium with aluminum which is especially suitable for use in making small castings with an induction-melting and casting machine. The effect of various crucible linings on the efficiency of the residual deoxidizer and accompanying oxide film in protecting palladium against oxidation during remelting also has been examined; the preferred crucible lining consists of zirconia cement. THE objective of this work was to develop a simple method of deoxidizing induction-melted palladium which would be suitable for use by manufacturers of jewelry and other small castings. In a common method of deoxidizing torch-melted palladium a piece of aluminum foil is dropped on the surface of the molten metal. If a film is present, which is usually the case, it must first be removed by oxidizing the molten metal thoroughly because it would interfere with the entry of the aluminum into the melt. Removal of the film is probably facilitated by a mild fluxing action of the silica crucibles which are used for torch-melting. However, removal of an alumina film from molten palladium in the crucibles normally used for induction melting is a much slower process and it became necessary to modify the de-oxidation procedure. In the modified procedure the charge is simply melted and the desired amount of aluminum, crimped to one end of a tungsten wire, is plunged through the film into the palladium and the wire immediately withdrawn. The trace of tungsten which dissolves along with the aluminum can be avoided, if considered objectionable, by using a palladium wire. In view of the persistence of the alumina film under the conditions of induction-melting it also was decided to ascertain the efficiency of this film in protecting palladium against oxidation during repeated remelting and casting. Melting Equipment and Materials The equipment used for melting and casting consisted of an Ecco GC:6, 6 to 8-kva high-frequency converter and an Ecco M34B centrifugal casting machine. This unit is being increasingly used for making jewelry and dental castings and it also has been found useful in making exploratory melts of a variety of nickel alloys, for which purpose it is well suited on account of its speed of melting and economy of material. A description of the machine and its operation will be published elsewhere.' A common palladium jewelry alloy, 95.5 palladi-um-4.5 ruthenium (referred to as "palladium" in the trade), was selected for the deoxidation tests. It was available as melting stock which had been melted in air to free it from oxidizable impurities, and also as clean scrap from previous melts which had been deoxidized with aluminum. The latter was thought to be typical of clean "palladium" scrap to be found in a manufacturing jeweler's establishment and it is also similar to one brand of "casting palladium." By the same token, the oxidized melting stock corresponds to "casting palladium" after the latter has been melted and thoroughly oxidized: Pure aluminum wire (99.9 pet), 0.032 in. diam; 1 in. = 0.036 g. Scrap tungsten wire, 0.014 to 0.020 in. diam. Argon, commercial water-pumped; 99.9 pet pure Experimental Procedure Samples of about 50 to 75 g of the palladium alloy were melted in a crucible lined with a proprietary refractory alumina cement. Some charges were melted in air, others in argon. The oxidized melting stock was melted and solidified a number of times in order to remove as much oxygen as possible before deoxidizing, but this treatment was unnecessary in the case of scrap. In either case the metal was deoxidized with aluminum (0.01 to 0.05 pet) by the

Jan 1, 1959

Abbey, Robert Graham, District Mgr., The W. W. Sly Mfg. Co., 50 Church St., New York, N. Y. '21 Abbott, A. N Ave. Morelos 84, Cuernavaca, Morelos, Mexico '23 Abbott, Argyle Campbell, Geol 42 Everett St., Arlington, Mass. '29 Abbott, Clarence E., V.P., Charge of Raw Materials, Tenn. Coal, Iron & R. R. Co., 1242 Brown-Marx Bldg., Birmingham, Ala. '04 Abbott, Louis Benjamin, Chief Engr., Consolidation Coal Co., Watson Bldg., Fairmont, W. Va. '15 Abeel, George H., Jr., Cons. Min. Engr 1281/2 S. Canon Dr., Beverly Hills, Cal. '18 Abel, Raymond L., Asst. Prof., Dept. of Pet. Refin., Univ. of Pittsburgh. .Pittsburgh, Pa. '28 Abel, Walter D., Cons. Engr 650 S. Grand Ave., Los Angeles, Cal. '82 Abele, Louis T., Min. & Met. Engr., Supt., Texas Hill Mine Coulterville, Cal. '31 Abell, Leo M. Millicent, S. Australia '31 Abernathy, George Elmer, Prof. of Geol. & Min., Kansas State Teachers College, Pittsburg, Kan. '20 Aborn, Robert H., Research Lab., U. S. Steel Corp. Lincoln Highway, Kearny, N. J. '19 Abozeid, Mahmood, Dept. of Mines & Quarries Cairo, Egypt '26

Jan 1, 1932