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The Institute is custodian of funds for support of numerous gold medals and prizes and has representatives on boards awarding still others. Details regarding the Institute Awards are given below. The Institute is represented on the boards of the John Fritz Medal, the Hoover Medal and the Washington Award, in connection with the three national societies of Civil, Mechanical and Electrical engineering; and, also, in the case of the Washington Award, with the Western Society of Engineers. Robert W. Hunt Medal and Prize THE partners of Robert W. Hunt established a fund which was presented to the Institute at a fitting ceremony on May 27, 1920, to establish an annual medal and a sum of money to be awarded under the following rules: 1. The award shall consist of two prizes: first of a gold medal, second of a sum of money; a certificate to accompany each prize. The money prize shall not be awarded to a member over 40 years of age, but under unusual circumstances, both prizes may be allotted to one person provided that he is not over 40 years of age. In general it will be understood that the Committee shall award the money prize to the younger men, rather than the medal. 2. The awards shall be made not oftener than once a year to that person or persons contributing to the Institute the best original paper or papers on iron and steel. The scope of the term "iron and steel" shall be determined by the subcommittee considering the awards. In general, papers dealing with the practical side of the subject have preference over those dealing with the theoretical side in recognition of the fact that Captain Hunt's main contributions to the industry have been in the improvement of production and quality of material. 3. A subcommittee of three to five, including the Chairman of the Iron and Steel Division, shall be appointed by the Iron and Steel Division annually to adjudge the award subject to approval. 4. The awarding committee shall submit its report to the Iron and Steel Committee at its October meeting, and the award shall be certified to the Secretary of the Institute in time to permit the presentation to be made at the Annual Meeting of .the Institute. 5. The recipient of the award shall be designated "The Hunt Medalist." Awards of the medal have been made as follows: 1920—-Robert Woolston Hunt. 192G—John A. Mathews. 1926—Charles Lewis Kinney, Jr. 1929—Edgar Collins Bain. 193G—James Aston. Awards of the prize have been made as follows: 1928—C. H. Herty, Jr. 1929—William E. Griffiths.

Jan 1, 1930

By Albert G. Zima

ACCORDING to recently published statistics, it is predicted that as much oil must be produced during the next 16 years as has been produced during the past 75, in order to satisfy the high rate of consumption of petroleum products. During 1934, over 17,000 oil wells were completed in the United States, and it is expected that over 20,000 additional wells will be drilled during the current year. Were it not for the remarkable progress made during recent years in the improvement of drilling technique and in the development of equipment used in the production phase of the oil industry, it is doubtful whether sufficient oil could be produced to meet present requirements. A few years ago, wells seldom were deeper than 3500 to 4000 ft., owing to the limitations of the drilling methods and equipment employed.. Today, 'however, through the application of scientific drilling methods and the adaptation of modern equipment and improved materials, many wells range from 6000 to 8000 ft. in depth, and a few recent completions exceed 10,000 feet. DRILL TOOLS Modern rotary drilling tools are the product of ingenious design and careful selection and adaptation of materials used in their construction. They must withstand terrific abrasion and, because of their compactness, must be designed to resist exceedingly high unit stresses. In bits, core drills and reamers, the bodies are made of either forged or cast alloy steels, heat-treated to develop a combination of high strength and toughness. To provide sufficient strength to the threaded portions and to protect the threads from distortion or damage, the box or pin sections of the tools are hardened to approximately 310 to 330 Brinell hardness

Jan 1, 1935

Considerable attention has been, and is being, given to the physics of water-films associated with bubble interactions at surfaces. In contrast, little information on the chemistry of such films has been reported. This communication reports a method using sum frequency vibrational spectroscopy (SFVS) to describe hydrogen bonding of interfacial water molecules in water films created with bubbles at hydrophilic and hydrophobic surfaces. The SFVS spectra of water films at hydrophilic silica surfaces differ significantly from the spectra of water at a hydrophobic silica surface. The SFVS spectra indicate that a very ordered water structure exists in water films at the hydrophilic silica surface during contact with a bubble and that the extent of hydrogen bonding increases with an increase in contact pressure. Such structural considerations as well as repulsive electrostatic and Van der Waals forces account for film stability for a bubble at the hydrophilic silica surface. In contrast, the SFVS spectra of water at a hydrophobic silica surface show a lack of hydrogen bonding and are characterized by a distinct absorption at about 3700 cm-1 similar to the spectrum of the air/water interface. These results suggest the presence of a water void, or water exclusion zone, at the hydrophobic surface, as supported by X-ray reflectivity measurements reported in the literature, by atomic force microscopy, and by the results from molecular dynamics simulations. Of course the water film at the hydrophobic surface is unstable with film thinning and rupture upon bubble contact. Under these circumstances it is shown that an attractive Van der Waals force between the bubble and the hydrophobic surface can be expected when the water exclusion zone is taken into consideration. As the thickness of the water exclusion zone increases to a thickness corresponding to the size of nano bubbles, the calculated attractive Van der Waals force increases. This analysis may help to explain the so-called ?short range? and ?long range? hydrophobic forces. Keywords: SFVS spectra, hydrophilic silica surface, hydrophobic silica surface

Sep 1, 2012

By J. Etay, S. Daugan, Y. Fautrelle

"New type of electromagnetic parametric instabilities arising at the free surface of liquid metal in the presence of a low frequency magnetic field are presented. First, the mechanism of the instability is analysed in an idealised case. Then, the experimental device working with mercury is described. Various shapes, both regular and irregular, of free surface are found. A experimental stability diagram is obtained. Measurements of the deformation performed on photographs are compared with physical orders of magnitude.IntroductionWhen a liquid metal pool of electroconductivity a is submitted to an A.C. magnetic field B = B0 cos mt, electrical currents j are induced in the liquid metal and interact with the applied magnetic field to create electromagnetic body forces F = j x B. Those Lorentz forces comprise both a mean value (time average) and an oscillating part. Those forces are widely used in many metallurgical processes to stirr a liquid metal or to control its free surface, e. g., in aluminium continuous casting or electromagnetic levitation problems (1-3). When liquid metal free surfaces are submitted to AC. magnetic fields, the shape of those interfaces may interact with the applied field and leads to a various instabilities. A review of these instabilities may be found in Fautrelle (4). That instabilities may be a problem for the control of processing as electromagnetic levitation or quasi-levitation."

Jan 1, 1999

By Y. J. Wang

The ventilation network problem, having both fixed and nonfixed operating points as control devices, is examined in this paper. Emphasizing the concept of solving a system of n equations in n unknowns, this paper presents the generalized problem formulation, some conditions under which the problem does not have a unique solution, and a solution procedure based on the Newton (or Newton-Raphson) method. A numerical example is included.

Jan 1, 1989

By P. Fauvel, V. Nasri

In January 2001, French and Italian governments signed an agreement for the construction of a new Lyon-Turin railway line. This project includes a tunnel of 53.1 km length and a maximum of 2500 m overburden to be designed for a reference speed of220 km/h. The tunnel crosses major part of the West Alpine geological formations, which are very complex and contrasted in terms of the nature of rocks and the mechanical and hydrogeological conditions. In addition to the twin single-track tubes, numerous intermediary shafts, security station and intervention sites and cross passages should be built to respond to the security, operational and construction requirements. This paper describes the results of the preliminary engineering design and multiple challenges of this very long and deep railway tunnel.

Jan 1, 2005

By D. Carr, C. Anderson, M. Deal, C. Larson

"Construction of the OceanaGold Haile operation’s process plant in Kershaw, South Carolina is currently under way, with ore through the mill expected in late 2016 and commercial production expected in early 2017. The process is designed to treat 6,350 tonnes per day with minor upgrades required to achieve 8,270 tonnes per day. Plant optimization during detailed engineering, combined with a focus on de-risking the process, has resulted in numerous process changes since the initial design. This paper describes the plant optimization and de-risking, it also presents a proven commissioning strategy modelled after OceanaGold’s Didipio operation, whilst identifying potential expansion opportunities. INTRODUCTION Haile Gold Mine is located in Kershaw, South Carolina, approximately 50 miles south of Charlotte, North Carolina. Gold was first discovered at the site in 1827, and the property has been through several operating periods since. The last operation employed heap leaching from 1985 through 1992. Since then, the property has been closed and fully reclaimed. Romarco Minerals acquired the property in 2007, and began an exploration program that delineated 2.02Moz. of gold in reserve at an overall grade of 2.06 g/t. OceanaGold acquired Romarco Minerals and the Haile Operation in October of 2015. OceanaGold operates under a risk management philosophy in all aspects of operation, both corporately and at each individual business unit, and has implemented numerous process changes to eliminate or mitigate risks identified in the initial design of the processing circuit, and provided increased opportunity for optimization and expansion. This paper describes the plant optimization and de-risking, it also presents a proven commissioning strategy modelled after OceanaGold’s Didipio Operation, and identifies potential expansion opportunities. INITIAL PROCESSING CIRCUIT DESIGN An extensive metallurgical test work program was undertaken by Romarco Minerals and third party laboratories during the initial design phase of the Haile project [1]. This preliminary test work provided the technical information as a basis of plant design. The initial flow sheet for the Haile processing circuit is shown in Figure 1 (see APPENDIX). The plant is designed to process 6,350 tpd (7,000 stpd) on an annualized basis. The process begins with a jaw crusher followed by a SAG and ball mill grinding circuit to reduce particle size to P80 74 µm. A flash flotation cell treats 50% of the cyclone underflow in the ball mill circuit. Grinding circuit product is sent to a rougher flotation circuit to recover gold-bearing pyrite. The flotation concentrates from flash and rougher flotation are reground to P80 13 µm using stirred media detritors (SMD’s). The rougher flotation tail is pumped to the carbon-in-leach (CIL) circuit for gold recovery. The reground concentrate is pre-aerated prior to being pumped to the CIL circuit. The CIL circuit is a hybrid circuit with eight tanks. Tank 1 leaches the pre-aerated concentrate only, and tanks 2 through 8 leach the combined flotation tailing and tank 1 discharge. The carbon strip circuit is a standard pressure Zadra system, followed by electrowinning, and refining using an induction furnace. CIL tailing passes through a cyanide recovery thickener prior cyanide destruction and then pumped to the tailing storage facility (TSF)."

Jan 1, 2017

By E. W. Mehal, R. H. Cox

A planar Gunn oscillator was developed for use in a monolithic microwave integrated circuit. The device was designed to operate in the frequency range of 20 to 30 GHz with a continuous wave output. Selective epitaxial deposition was used to form the n+n-n+ device structure in (111)-B semi-insuluting GaAs. The active n- region was about 5 µ thick and was doped to about 2 x 1015 electrons per cu cm by the reactor background. The mobility was -5000 sq cm v-1 sec-1. The n+ epitaxial deposits were doped to 1 x 10" electrons per cu cm using S2Cl2. Planarity of the three DURING the past few years, new microwave devices in discrete form have been developed utilizing GaAs. The next logical step is to combine these devices in a successive deposits was quite good; total overgrowth was less than 1 µ. Metal ohmic contacts were applied to the n+ or n- regions using a Ag-In-Ge alloy. The n+n-n+ devices had symmetric IV characteristics and could be operated C. W. for both directions of device bias. Metal ohmic contacts made directly to the n-region always Produced asymmetric devices. C. W. operation was obtained over the 22 to 28 GHz frequency range. The best performance obtained was 1.5 mw C. LV. output at 28 GHz. microwave integrated circuit. A potential application would be a radar receiver operating in the millimeter wavelength region. The key component in such an integrated circuit is a microwave oscillator, recently described by Gunn.1, 2 Under the influence of a large electric field, high-resistivity GaAs exhibits a bulk negative resistance, and high-frequency current oscillations result. Since relatively high voltage and

Jan 1, 1969

By Wen L. Cai

This paper examines the effects of different block dimensions and cone bases on the economic open pit limit design based on case studies on a coal deposit consisted of two west- east elongated, near vertical thin seams starting with a base model dimension of 200x170x50 (NX*NY*NZ) with a block dimension of 10mx5mx4m (DX*DY*DZ), the blocks were combined along easting, northing and elevation directions. Two cone bases were used, one with a base radius of 10 meters, the other with a base radius of 0. Two pit design algorithms, one is the floating cone algorithm, the other is an optimum algorithm, were used to see which one of the two pit design algorithms is more sensitive to block dimension and cone base variations. The results are presented and analyzed.

Jan 1, 1992

By N E. Whitehead

An application to mine an ilmenite-rich sand deposit in Westland led to public concern about potential radioactive hazards should the ore be further processed to recover zircon or monazite. A review recommended that any material involved in the heavy mineral sand industry containing more than 0.05% thorium, uranium or their mixture should be considered a radioactive substance and, for mining purposes, a notifiable product. Safeguards for those occupationally exposed would operate via the Radiation Protection Regulations. The major safety requirement would be the minimisation of dust in certain operations.

Jan 1, 1993

By Niels Hansen

Dispersion-strengthened aluminum products consist of an aluminum matrix containing finely distributed ceramic or intermetallic particles. Examples of the two types of product are SAP, in which the dispersed phase is aluminum oxide, and materials made from atomized aluminum alloy powder, in which the dispersed phase can be FeA1, particles.' A fundamental difference between the two types of product is that the elongation of aluminum/aluminum oxide products decreases with increasing temperature, whereas the elongation of aluminum- FeA13 products, like that of aluminum alloys, increases with increasing temperature. As regards the structural stability, aluminum/aluminum oxide products are stable to temperatures above 600° C as aluminum oxide does not react with aluminum, whereas prolonged heating at above 400°C of aluminum-FeA1, products leads to coarsening of the intermetallic phase and loss of strength.' On the basis of these results it is supposed that a dispersion-strengthened product combining strength, ductility, and stability at elevated temperatures may be obtained if the dispersed phase reacts with the matrix in such a way that the reaction does not proceed at any significant rate at the application temperature. Different ceramic or intermetallic compounds may be selected as the dispersed phase, and, as alloying of the matrix phase may also influence the reaction, many possibilities exist for each metal. In the present study, aluminum products containing different oxides have been examined. For a reaction to take place between the dispersed oxide and the aluminum the free energy of formation of the oxide (MeO) must be greater than that of aluminum oxide; the difference should, however, not be too great in order to limit the reaction rate. Furthermore the aluminum alloy formed when aluminum reacts with the dispersed oxide should have a melting point near

Jan 1, 1969

By K. A. Slagle, D. K. Smith

weight obtained. Additives used in conjunction with salt in these slurries have included silica flour, calcium ligno-sulfonate and cellulose retarders, granular lost-circulation materials, bentonite and selected low-water-loss additives that are not significantly deteriorated by the presence of the chloride ion. In some other areas of South Texas, the salt-saturated slurries have been used quite extensively for improvement of the flow properties of slurries and attainment of better circulation characteristics at lower displacement rates. Concurrently with this property, the protection of shales and shaly sands is also realized, as well as useful retardation of the slurry. Resultant superior cementing jobs have been indicated by both communication tests and acoustic logs for bonding to pipe and formation.' In one section of Louisiana, a major oil company has been using salt-saturated API Class A cement with calcium lignosulfonate retarder for cementing through the Miocene at 9,000 to 10,000 ft. This is another of the situations where interbedding of sands and shales exists, creating difficulty in maintaining formation competency when a fresh-water slurry contacts the clay minerals of the formation. Further work has also been done in the shaly Miocene formation at 13,000 to 15,000 ft where fairly close water or gas contacts are encountered. Indications thus far are that better segregation of these various fluids is obtained by use of the saturated salt slurries because of their improved formation bonding characteristics. In addition to the properties of salt in this situation, attainment of turbulent flow at minimum displacement rates has also been accomplished by use of an additive to help provide exceptional dispersion and viscosity reduction of the slurry. Another oil company was encountering considerable expense in completing wells in Southwestern Louisiana due to extensive block squeeze requirements for effective separation of zones. A very effective mud program was being used to minimize washout in the shale sections and, apparently, a nearly gauge-size hole was being obtained. However, primary cementing results with fresh-water slurries were generally poor. On a few occasions when slurry was actually circulated to the surface, large pieces of shale formation were brought out of the hole with the slurry, indicating a severely water-sensitive, sloughing formation. Inhibition of shale heaving was being accomvlished in the drilling program, and immediately indone ipon circulation of the fresh-water slurry even though it contained a low-fluid-loss additive to reduce filtrate damage in the sands. The subsequent change to salt-saturated slurry yielded 11 successful primary cement jobs out of 12, compared to the previous success ratio of practically zero. Since these were deep, high-temperature wells in the range of 13,000 ft with high-pressure zones necessitating 17.5-lb/gal fluid densities, the slurry used was API Class E cement, silica flour, weight material, retarder, salt saturation (which also reduced the amount of weight material) and maintenance of low fluid loss by use of a salt-compatible additive. Other salt slurries have been used to a limited extent in this same general area for similar problems at depths ranging from 5,000 to 17,000 ft. In the shallower wells, the cement has usually been API Class A where the salt functions as a retarder, and in the deeper wells API Class E cement is used with the additional salt advantage being its increased slurry weight and inability to dissolve salt stringers. A considerable number of squeeze jobs have also been done on older wells using the salt-saturated slurries with very good results. MID-CONTINENT In North Texas, salt-water slurries have been used for cementing the Woodbine sand, Strawn sand, KMA sand and Pettit lime. Shales surrounding these formations have created the same difficulty in obtaining separation of producing zones that has been the problem in other areas. Depths in this area range from 3,400 ft for the Strawn to 7,400 ft for the Woodbine, and concentration of salt has varied accordingly. In the deeper wells, where retardation is desired, saturated salt-water cement is used; for the shallower wells, in order to provide shorter waiting-on-cement times, the amount of salt has been 18 per cent by weight of the mixing water. Results have been excellent with no reported failures on any of the salt cement jobs; where acoustic bond logs have indicated indifferent bonds previously, they are indicating very good bonding for the salt slurries. In Oklahoma various shales of Pennsylvanian age exhibit a high degree of sloughing in the presence of fresh water, causing severe washouts above and below sand formations which it is desired to isolate. This situation exists to some degree in practically all parts of Oklahoma and includes formations of other ages such as the Wood-ford shale. For the past few years, salt-saturated cements and displacement rates as high as practical have been used as a remedy for this problem, with very good results. The Layton and Bartlesville formations are two examples of shaly sands where saturated slurries have been helpful. In one area where five wells were drilled through this type of problem shale without obtaining a satisfactory primary cement job, a change was made to salt-saturated cement preceded by a suitable chemical wash for the drilling mud involved. Acoustic bond logging indicated excellent bonding, and final completion bore out this result by being trouble-free. This type of slurry has also been used extensively on squeeze jobs where shales have been heaving around the producing formations. Predominantly, the basic slurry has been either API Class A cement or a pozzolan cement—although, as deeper wells are being drilled, the use of salt in Class E cement is also increasing. Salt cement in West Texas has been used primarily to help prevent channeling through the shales around the Delaware sand, Queens dolomite and Hope lime. Many of the shaly and dirty sands of this area are sensitive to the filtrate from a fresh-water cement. Salt at 16 to 18 per cent by weight of mixing water has been added to centent, and has been effective in controlling formation damage and communication between zones in these formations. Use of these lower salt concentrations is dictated in this area by the relatively low formation temperatures where retardation of the slurry would create unduly long waiting-on-cement times. Also, quite a bit of cementing has been done in this area using salt concentrations in the accelerating range— that is, 2 to 5 per cent by weight of water. Specifically, these concentrations have been used in coiljunction with high percentages of gel to overcome the retarding effect of the calcium lignosulfonate dispersant, although there are probably several shales where these concentrations could provide some degree of formation stability. On several occasions, the salt has also been used to lower the critical velocity or rate for turbulence with the slurry, particularly in the pozzolan cements. On wells in the Hope lime, it has usually been necessary to squeeze the shale above and below the lime to get a water-free completion. Use of salt-saturated slurries has largely eliminated this

By George Burke

"Many soil mixing methods have evolved over the years, but the Trench Cutting Re-mixing Deep method (TRD) was developed in Japan, circa 1993, to construct continuous uniform cutoff walls, without the need for an open trench. TRD mixing has been used on over 300 projects in Japan for excavation support, groundwater barriers, liquefaction mitigation, soil improvement and pollution containment. To date, TRD mixing has been used on only three projects in the United States: a test cell in Long Beach, Calif., for seawater intrusion barrier in 2004; a groundwater barrier at a wastewater treatment plant in Lincoln, Calif., in 2005; and presently at Herbert Hoover Dike surrounding Lake Okeechobee in southeastern Florida.The most notable benefits of TRD are its abilities to overcome difficult geology, such as layered rock and dense cobbles and gravels that hinder other soil mixing methods, and to create extremely high-quality walls. The method is ideal for situations in which access precludes the use of more traditional methods due to spoil control, such as waterways and congested urban environments or subsurface obstruction/difficult ground. Spoil disposal is minimized since TRD mixes the soil in place.TRD mixing has a horizontal continuity advantage over traditional multi-auger deep soil mixing (DSM) systems. Because DSM systems create walls by overlapping soil-cement columns, the auger may be deflected by difficult ground, and gaps are possible. Gaps may also occur when constructing an exceptionally deep wall due to the possibility of auger deviation from its required vertical alignment.The method also has a homogeneity advantage in layered soils. Because DSM constructs columns by rotating the defined length mixing tools up and down the soil profile while injecting binder, strength and permeability in each layer will vary. The TRD method vertically mixes the entire profile and core samples show highly uniform strength. It is most cost-effective in deep difficult ground such as layered rock or dense cobbles and gravels."

Jan 1, 2009

By J. T. Norton, Joseph Gurland

IN spite of the extended use and high state of practical development of the cemented tungsten carbides, the structure of these alloys is still a matter of considerable controversy. The characteristic high rigidity and rupture strength of sintered compacts have been attributed to a continuous skeleton of tungsten carbide grains, formed during the sintering process. This view is based mainly on the work of Dawihl and Hinnuber,1 who reported that a sintered compact of 6 pct Co maintained its shape and some of its strength after the binder was leached out with boiling hydrochloric acid. After leaching, only 0.04 pct Co was reported to remain in the compact. They also showed that the assumed increasing discontinuity of such a skeleton, as the cobalt content is increased, could be made to account for the observed discontinuous increase of the coefficients of thermal expansion, the loss of rigidity, and the impaired cutting performance of alloys of more than 10 pct Co. Contradictory evidence was cited by Sanford and Trent,' who mentioned that a sintered compact was destroyed by reacting the binder with zinc and leaching out the resulting Zn-Co alloy. The skeleton theory also does not account for the observed change of strength of sintered compacts as a function of cobalt content. If the skeleton is responsible for the strength, the latter would be expected to decrease with increasing binder content. Actually, the strength increases and reaches a maximum around 20 pct Co. In addition, tungsten carbide is brittle and undoubtedly very notch sensitive. The highest value found in the literature for the transverse rupture strength of pure tungsten carbide prepared by sintering is 80,000 psi.3 herefore, such a skeleton does not easily account for a rupture-strength value of 300,000 psi and higher, commonly found in sint.ered tungsten carbide-cobalt compacts. In view of the conflicting data present in the literature, experiments were undertaken to determine whether the sintering of tungsten carbide-cobalt alloys leads to the formation of a carbide skeleton or whether the densification behavior and the properties of cemented compacts are consistent with a structure of isolated carbide grains in a matrix of binder metal. The specimens were prepared from powders of commercial grade. Tungsten carbide powder ranged in particle size from 0 to 5x10-4 cm. Mixtures of tungsten carbide and cobalt were ball milled in hexane for 48 hr in tungsten carbide lined mills. After milling, the specimens were pressed in a rectangular die (1x1/4x1/4 in.) at 16 tons per sq in. NO pressing lubricant was used. Sintering of the tungsten carbide-cobalt compacts was carried out in a vertical tube furnace equipped with a dilatometer (Fig. I), by means of which the change of length of the powder compacts could be followed from room temperature to 1500°C. An atmosphere of 20 pct H, 80 pct N was maintained inside the furnace. Decarburization of the samples was prevented by the presence of small rings of graphite inside the furnace tube. The temperature of the sample was measured by a platinum-platinum-rhodium thermocouple, which also was part of a temperature control system able to maintain a constant temperature within ±100C. Pure tungsten carbide compacts were prepared by sintering the carbide without binder or by evaporating the binder from sintered compacts in vacuum at 2000°C. Since complete densification of these samples was not desired, they were sintered only to 60 or 80 pct of the theoretical density of tungsten carbide. The specimens were prepared for metallographic examination by polishing with diamond powders and etching with a 10 pct solution of alkaline potassium ferricyanide. Cobalt etches light yellow and the carbide gray. The amount of porosity is exaggerated since it is difficult to avoid tearing out carbide particles, especially from incompletely sintered samples. Experimental Observations A number of specific experiments were carried out in order to study some particular aspect of the sintering problem. The details of these experiments, together with their results, are as follows: Electrolytic Leaching: The binder was removed by electrolytic leaching from sintered tungsten carbide-cobalt compacts for the purpose of determining the continuity of the carbide phase. The method used was based on the work of Cohen and coworkers4 on the electrolytic extraction of carbides from annealed steels. If the sample is made the anode, using a 10 pct hydrochloric acid solution as the electrolyte, the binder is dissolved, but the rate of solution of tungsten carbide is negligible. A current density of 0.2 amp per sq in. was applied. As shown in Fig.

Jan 1, 1953

By M. Mirnezami

Pentlandite samples were obtained as Ni concentrate from three Canadian plants and one specimen sample from Ward?s Scientific Establishment. The samples were upgraded using gravity and magnetic separation techniques. Nickel concentration was determined by atomic absorption spectroscopy. Microprobe analysis identified a range in Co and Cu lattice substitutions. All samples exhibited similar zeta potential-pH trend with isoelectric points from 2 to 3, and similar responses to copper activation and addition of xanthate. The similar trends indicate that the variations in lattice substitution identified have no significant effect on electrokinetic properties; that is, samples from any source likely yield results that can be generalized.

Sep 1, 2012

By Ronald E. Hamilton

"An attempt to review the recent literature on comminution reveals at once that the subject has many ramifications and that the applications are so diverse that there are very few general statements which can be made.It. seems reasonable to start classification on the basis of size of material as Input to the comminution process. However, we find that this can only be done in a very imprecise manner.The initial step of breaking rock from its natural state of very large pieces in geological formations into sizes suitable for processing is accomplished by blasting. This step in the process has not been ex-amined in this project except to note that great changes have been made during the last decade or so in the explosives used, and in the method of handling them. We should determine what effect changes in mining methods can have on the need for crushing.The second step in the process is usually primary crushing, performed by gyratory or jaw crushers. The largest chunk which can be fed to a jaw crusher depends on the size of the machine, and should be larger than the largest fragment produced in the miring process. It is obvious that the larger the crusher, the less care required in mining to en¬sure the absence of rocks too large to be crushed. The optimum size of crusher to minimize overall cost of mining and reduction is not at all obvious, and no information on this point has come to light in this investigation.It is rather generally accepted that size reduction is most efficiently done in small stages, and that different machines have different opti¬mum size ranges of feed. For example, crushers are preferred for sizes above about 1"", rod mills for the range between 1"" and 0.1"", ball mills are preferred from 0.1""down to perhaps 10 microns, and vibratory mills, or jet mills, below 10 microns."

Jan 1, 1976

By D. J. Jr. McAdam

PART I.-OUTLINE OF INVESTIGATION, DESCRIPTION OF METHODS AND MATERIAL Previous Investigation of the Influence of Stress on Corrosion IN 1917 Haigh1 presented evidence that under simultaneous corrosion and cyclic stress metals may fail at lower stresses than if the corrosion is prior to the cyclic stress. In 1926 the author, while investigating the cooling effect of water on the fatigue resistance of metals, found that under these conditions steel specimens fail at stresses far below the endurance limit.2 (By "endurance limit" is here meant the fatigue limit obtained with specimens as free as possible from stress concentration and corrosive influences.) This led to an investigation (at the Naval Engineering Experiment Station, Annapolis, Md.) of the influence of cyclic stress on corrosion. This investigation maybe divided into three parts. The first part was a general survey of the conditions necessary to cause complete failure under corrosion and cyclic stress of relatively high frequency. The entire process by which metals fail under these conditions was-called "corrosion-fatigue." "Corrosion-fatigue limits" for a large number of metals were determined and the relationships of these limits to chemical composition, heat treatment and physical properties were established. The conclusion was reached that corrosion-fatigue is due to the accelerating influence of cyclic stress on corrosion. Results of this part of the investigation were presented in five papers.2-6 The second part of the investigation was a preliminary study of the influence of cyclic stress on corrosion. Each experiment was conducted in two stages. The first was a corrosion stage in which the specimen was corroded under cyclic stress; the second was a fatigue stage, in which the previously corroded specimen was tested (without further corrosion) to determine its fatigue limit. The difference between this fatigue limit and the endurance limit was used as a criterion of the "damage" due to

Jan 1, 1931

By N. P. Haran

A detailed study was undertaken to beneficiate sub-grade iron ore sample from Kenojhar District, Orissa, India containing 57% Fe (T), 7.7% SiO2, 4.8% Al2O3, 4 % L.O.I. 0.4% TiO2,1.3 % Mn and traces of S(T) to make it suitable for the user industry. The mineralogical study indicated that it predominantly consists of haematite with subordinate amounts of goethite and clay. Quartz, Cryptomelane / Psilomelane, Pyrolusite, Gibbsite, Feldspar and Muscovite mica were present in very minor to trace amounts. The Denver grind ability tests indicated, that the sample could be categorized as ?medium soft to medium.? The Bond ball mill work index was determined to be 14.19 kwh per short ton. The beneficiation process involved classification followed by tabling of the classified sand, ground to minus 48 mesh size. The table slimes were subjected to Wet High Intensity Magnetic Separator (WHIMS). The developed process yielded a composite concentrate from tabling and WHIMS operations assaying 65% Fe(T), 2% SiO2, 1.8% Al2O3, 2% Mn and 0.9% LOI with a recovery of 60.1% Fe (T), amounting to 52.5 wt.% yield. To meet the size specifications for pellet making, it was further ground. Dewatering studies were also carried out on the ground combined concentrate and rejects. The thickener area of ground combined concentrate using 0.02 kg/t of Sufloc A 1115 flocculant was 0.02 m2/tonne of dry solids per 24 h. And for the combined rejects using 0.12 kg/t of flocculant, it was 0.035 m2/tonne of dry solids per 24 h. The moisture content, in the pressure filtration cake, in the ground combined concentrate product was 10.0%, and productivity was 506.7 kg/m2h. Thus, by thickening and filtration of process products, 90% of water used in the process could be recovered. The study highlights the development of a simple and cost effective flowsheet with almost complete water recovery for a subgrade iron ore sample. Keywords: tabling, WHIMS, thickener, filtration

Sep 1, 2012

By J. S. Marsh

The student of steelmaking is all too well acquainted with the fact that in many instances he must deal with data that in graphical representation exhibit the property most desirable in bird shot. This is scarcely mystifying, since the effort to establish one variable as a function of another is usually hampered by the simultaneous operativeness of two or three other factors that may be important. A large part of arriving at relationships that have the pleasing self-consistency of, say, precise measurements of thermal expansion, consists of determining what factors must be held constant-—an even larger part usually consists of collecting data for which those factors have been so maintained. It is not intended to imply that functional relationships in the physical chemistry of steelmaking are hopelessly obscure; on the contrary, it is merely necessary to be undisturbed by marked deviation of some points from a curve that otherwise makes sense. A reaction mechanism suggested by such a curve may call attention to hitherto unsuspected factors operative in the origin of the deviating points, and thus permit another step to be taken in the direction of fuller understanding. It is proposed, therefore, to suggest several empirical relationships. Even though the approach is not always rigorous, deviations caused by simplifying assumptions appear to be too small to obscure a provisional It has been appreciated for some time that the carbon-oxygen reaction in liquid steel is highly important. For example, Körber et al.,' in introducing a summary of their extensive work on steelmaking reactions, said: "... the far-reaching and truly dominating action of carbon upon the metallurgical reactions will be especially stressed ..." In "Basic Open Hearth Steelmaking"2 (hereafter BOHS, for simplicity), it is accepted repeatedly that the various slag-metal interactions are nearly always controlled by the carbon-oxygen reaction. Before further discussion of this reaction, however, it will be worth while to consider briefly the carbon-oxygen equilibrium. In BOHS (p. 483) it is stated that: When liquid iron is brought into contact with gases containing carbon monoxide it absorhs carbon and oxygen. Conversely the carbon and oxygen in the metal unite to form carbon monoxide which is evolved from the bath during the open-hearth boil or while rimming ingots are solidifying. . . . When the equilibrium pressure is one atmosphere the equilibrium-constant equation simplifies, on the assumption that the activity of each element is equal to its percentage, to a constant which has been so much used that it has acquired a special symbol m. where m = %C X %O

Jan 1, 1945

By Pedro Tumialán

En el proceso de exploración de yacimientos se utilizan las deducciones de las secciones longitudinales construidas como resultado de trabajo de gabinete de datos que se obtienen en el campo presente. En ese sentido, el presente texto señala algunos casos aplicados en el Perú con el objeto de incidir de manera indirecta la importancia de un método más usado en exploración.

Mar 1, 1973