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By John Newby, Ulf Gwildis, Fred Marquis

From the Brightwater Conveyance System in Seattle to the Second Narrows Water Supply Tunnel in Vancouver, BC, the design and construction of deep-lying tunnels in the Pacific Northwest often require the incorporation of deep portal shafts. Alluvium overlying marine and glacial deposits combined with the high regional seismicity is the common geologic setting. The latest example illustrating the development of shaft design for this scenario is the 40-m-deep shafts of the Annacis Island Wastewater Treatment Plant New Outfall System. The main components of the shafts include the initial lining, providing the excavation support system to be used for launching and receiving a 5-m-diameter TBM; and the final lining, designed to withstand all static and seismic loads and to remain viable for the intended design life. This paper presents design and construction considerations for these shafts against the background of and lessons learned from past project experiences.

Jun 13, 2021

By Caroline Gomes de Oliveira

As fibras lignocelulósicas representam vantagens econômicas, técnicas e ambientais em comparação com as fibras sintéticas, como fibra de vidro por exemplo, quando se considera as alternativas de reforço aos compósitos. A fibra natural usada no presente trabalho é a fibra de eucalipto, que é largamente cultivada em território brasileiro. Este trabalho tem como objetivo avaliar uma análise estatística da correlação entre o diâmetro e a densidade da fibra de eucalipto. Para isso, foi aplicado o método de Weibull. O diâmetro foi obtido por meio de medições em projetor de perfil, enquanto a densidade utilizou determinações precisas da massa e do volume de fibras. Os resultados revelaram uma dependência inversa entre o diâmetro da fibra de eucalipto e sua densidade

Aug 17, 2017

By Letícia dos Reis Gonçales

A liga AZ91D apresenta 9%pAl e 1%pZn e pode ser submetida a tratamento térmico de solubilização seguido de envelhecimento para melhoria de propriedades mecânicas por meio de precipitação da fase beta-Mg17Al12. Esta fase, porém, pode ter efeitos distintos sobre o comportamento de corrosão da liga. Buscando estudar a influência do tamanho de grão da matriz alfa e a presença de precipitados beta sobre a resistência à corrosão da liga AZ91D, este trabalho utilizou lingotes com estrutura bruta de fusão na obtenção de amostras solubilizadas, laminadas a frio e então envelhecidas, para subsequente análise microestrutural e do comportamento de corrosão. A solubilização ocorreu a 445ºC por 24h e foi efetiva em dissolver quase completamente a fase beta. A laminação levou a uma redução de 20% da espessura das amostras e de 400 para 130 µm o tamanho de grão médio, após envelhecimento. O envelhecimento feito a 200ºC em 2 e 24h permitiu a precipitação de fase beta em maior quantidade e melhor distribuição por contornos de grão em relação às amostras fundidas ou solubilizadas. Ensaios de imersão foram realizados, apontando uma leve queda na taxa média de corrosão quando se lamina a amostra, enquanto as amostras solubilizadas (sem fase beta) mostraram maior susceptibilidade à corrosão. Assim, é possível indicar que o refinamento de grãos é benéfico ao formar uma rede de proteção em ligas de magnésio AZ91D, apesar de introduzir defeitos gerados pela laminação.

Aug 17, 2017

By F. H. McDowell

DURING the last eighteen months the Tilly Foster Iron Mine Company, the President of' which is Mr. E. I?. Hatfield and the Managing Director Mr. B. G. Clarke, has been carrying out a plan

Jan 1, 1889

By C. A. Stetefeldt

FoR the convenience of those who do not care to enter into the details of this long essay, I begin with a summary of the most important results it presents. The extraction of silver by the lixiviation-process from ores which have been subjected to a chloridizing-roasting, is based upon the fact that silver chloride is easily soluble in solutions of sodium or calcium hyposulphite, and that silver is precipitated from such solutions by an alkaline sulphide, with regeneration of the hyposulphite salts. In case the ore contains lead a large portion of the latter is and dissolved, lead sulphate being soluble in hyposulphite solutions. If, at the same time, copper is present, the sulphides precipitated from the solution, contain silver, copper, and lead, a combination of metals not desirable for subsequent treatment. Mr. E. H. Russell, of Park City, Utah, is the inventor and the patentee in the United States and several foreign countries of a new lixiviation-process, based upon the chemical facts discussed in this paper. Mr. Russell has discovered that lead can be completely separated from a sodium hyposulphite solution, as lead carbonate, by sodium carbonate or purified soda-ash, without precipitating any copper or silver. After decanting the solution from the lead carbonate, silver and copper are obtained from it in the usual way. This method of separating lead prohibits the use of calcium poly-sulphide as a precipitant for the sulphides, because any calcium entering the regenerated lixiviationsolution would also be precipitated as a carbonate with the lead by soda-ash. Hence, a sodium sulphide must be employed. A full investigation has demonstrated that this is by no means detrimental. Sodium sulphide and hyposulphite are more advantageously used in the lixiviation-process than the corresponding calcium-salts. Another defect in the lixiviation-process consisted in the necessity of a very perfect chlorination of the silver in the ore, because silver in

Jan 1, 1885

By BHAMIDIPATI S. SASTRY, ANMAYA NAIK, ASIF AHMAD, Srivatsan Jayaraman Sridharan, ADITYA PANDEY

Wet kata cooling power (WKCP) as measured by a kata thermometer is a well-known heat stress index used in the mining industry. Although, over the years, several researchers proposed different heat indices and indicated limitations of the kata thermometer, WKCP is used in the South African gold mining industry due to its simplicity and rapidity of assessment. This paper presents a comparative analysis of the newly developed empirical expression for the WKCP and some of the more commonly used empirical models. For this purpose, WKCP measurements are obtained based on experiments conducted in a low-speed wind tunnel. Based on a regression technique, the analysis presented aims to assess the disagreement between the empirical model predictions and actual measurements. The correlation is also presented between WKCP and the well-established thermoregulation models using parameters from the low-speed wind tunnel experiments, including dry-bulb temperature (Td), wet-bulb temperature (Tw), barometric pressure (P), and wind speed (v). It is found that the proposed empirical model for the WKCP represents the bioclimatic interaction quite well under the specific parameters that defines the harsh thermal environment and air condition, such as metabolic activity, clothing of the person, and the velocity of the ventilating air in which the person is working. The statistical analyses performed show that the empirical model proposed for the WKCP produces satisfactory estimates of the thermal stress experienced under lower air velocities, light clothing, and higher metabolic activity rates.

Sep 2, 2021

By M. D. Amirova

Cyanide-free technology of complex copper-lead ores flotation may be improved through enlarged range of pH values, enhanced copper recovery into copper concentrates due to additional recovery of secondary copper sulfides, as well as through enhanced efficiency of lead sulfides depression in process of new flotation modifiers-based selective separation. Study of the effects of flotation modifier (of metal nature) on minerals surface conditions proved that the xanthate is practically not adsorbed on the galenite surfaces due to minerals hydrophilization. Joint effects of sodium sulfite and modifier enhance process conditions for intensive galenite depression and at the same time for effective chalcopyrite and chalcosine flotation within a large pH values range (from pH=8 to pH=10). Identified mechanisms carry inference that proposed chemical reagent treating method is very promising for selective copper-lead concentrates separation. Potential use of carbon-containing materials as zinc flotation modifier to enhancing zinc recovery in processes of lead-zinc ores treatment has been studied. In our flotation tests we used Shalkiya (South Kazakhstan) lead-zinc ores containing such impurities as carbon shales, which presence impedes the process of saleable concentrates production and gives rise to excessive consumption of flotation agents due to the xanthate adsorption on the carbon. Lead and zinc concentrates were produced by process stages as follows: ores milled to 95% Cl. -0.074 +0; lead and zinc roughing flotation and further recleaner and testing operations. Test flotation in open process cycle resulted in enhancing zinc recovery into zinc concentrates by 21.1% and increasing zinc content in zinc concentrates by 3.96% that evidences promising potentialities for use of carbon-containing products as additional zinc flotation modifier. Works were carried out under National Program 2003~2005 of fundamental researches ?Physical and Chemical Mechanisms of Interactions in Multicomponent Solid and Liquid Systems Specific for Integrated Processing of Complex Metal-Containing Minerals and Technogenic Raw Materials? and contractual Agreement 2005 Optimization of Production and Technology of Shalkiya Lead-Zinc Ores Processing at Kentau Dressing Works.

Jan 1, 2014

By Larry A. Haas

The U.S. Bureau of Mines, in cooperation with Cleveland-Cliffs, Inc. (Hibbing, MN), investigated ways of enhancing the quality (compressive strength, after-tumble and reducibility) of domestic acid and fluxed magnetite pellets by modifying the oxygen content during the preheat and induration periods of the firing operation . Oxidation of magnetite was best accomplished when sufficient oxygen and time were available before the peak induration temperature was reached. The rate of magnetite oxidation increased directly with the gas oxygen content during the preheat period at 7000 C and above. With 30 pct ( or more) O2 and a preheat rate of 2000 C/min, most of the magnetite was oxidized during the preheat period. With laboratory tube and mini-pot furnace tests, oxygen enrichment during the preheat period improved the pellet properties more in the simulated grate-kiln tests than in the simulated straight-grate tests. The longer induration period with the grate-kiln test resulted in more sintering of the residual magnetite and its reaction with the silicon compounds. When flux was present in the pellets, calcium silicates and calcium and magnesium ferrites were formed. More calcium ferrite was formed when the magnetite was oxidized early and less iron was present in the fayalitic calcium silicate slag.

Jan 1, 1993

By H. Cevizci

"Numerical simulation of the plaster stemming method (PSM) was performed and compared with the conventional drill cuttings stemming method (DCSM). Many earlier in situ tests have proved that PSM can use the blast energy more efficiently than DCSM. Despite PSM generating more blast vibrations, it has advantages over DCSM such as better fragmentation and lower cost per unit volume of rock blasted. In this study, numerical simulation with Autodyn software using a 2D tool was employed to prove the efficiency of plaster stemming by comparing parameters such as pressure, Y-velocity, Y-force, internal energy, acceleration-Y, and compression. For example, the maximum pressure attained at the top of explosive column was 7 395 MPa for DCSM whereas it was as high as 11 945 MPa for PSM. Most of the computed parameters were significantly higher in PSM than those obtained for DCSM. This paper is the first study elucidating the efficiency of PSM by numerical simulation. It is concluded that PSM can save substantial amounts of money and effort. IntroductionThe stemming of blast-hole collars in surface mines with an inert material redirects blasting energy to the rock more efficiently, thus the blast-induced energy is utilized more effectively in breaking rock. With proper stemming, the gases should not escape due to loose stemming material. More efficient stemming with better confinement therefore increases the blast fragmentation. In addition, the distance of scatter is increased, giving rise to a looser rock pile that can be more easily loaded and transported. In order to improve the performance of a blast, stemming is used to help maintain the gas pressure over time (Konya and Konya, 2018). Proper stemming has been shown to increase the explosive efficiency by over 41% (Snelling and Hall, 1912).The most common stemming material in open pits and quarries is drill cuttings because of their ready availability at blast sites and the drill cuttings stemming method (DCSM) is a low-cost method. However, it has a major disadvantage in that dry drill cuttings eject very easily from blast-holes during an explosion, thus a great percentage of the blast energy is wasted and lost to the atmosphere. Cevizci (2012, 2014, 2013, 2017) studied blasting parameters in open pits and obtained better results with the plaster stemming method (PSM) in many limestone, basalt, and clay quarries. Moulding plaster is preferred for stemming because of the fast hardening time of 25–30 minutes."

May 1, 2019

By E. W. Filer, L. S. Darker

ONE of the primary purposes of this investigation was to determine how far blast-furnace metal and slag depart from equilibrium, particularly with respect to sulphur distribution. In studying the equilibrium between blast-furnace metal and slag, there are two approaches that can be used. One method is to use synthetic slags, as was done by Hatch and Chipman;' the other is to equilibrate the metal and slag from the blast furnace by remelting in the laboratory. In the set of experiments here reported, metal and slag tapped simultaneously from the same blast furnace were used for all the runs. The experiments were divided into two groups: 1—a time series at each of three different temperatures to determine the t.ime required for metal and slag to equilibrate in various respects under the experimental conditions of remelting, and 2—an addition series to determine the effect of additions to the slag on the equilibrium between the metal and slag. An atmosphere of carbon monoxide was used to simulate blastfurnace conditions. The furnace used for this investigation was a vertically mounted tubular Globar type with two concentric porcelain tubes inside the heating element. The control couple was located between the two porcelain tubes. The carbon monoxide atmosphere was introduced through a mercury seal at the bottom of the inner tube. On top, a glass head (with ground joint) provided access for samples and a long outlet tube prevented air from sucking back into the furnace. The charge used was iron 6 g, slag 5 g for the time series, or iron 9 g, slag 7 % g for the addition series. This slag-to-metal ratio of 0.83 approximates the average for blast-furnace practice, which commonly ranges from about 0.6 to 1.1. A crucible of AUC graphite containing the above charge was suspended by a molybdenum wire in the head and, after flush, was lowered to the center of the furnace as shown in Fig. 1. The cylindrical crucible was 2 in. long x % in. OD. The furnace was held within &3"C of the desired temperature for all the runs. The temperature was checked after the end of each run by flushing the inner tube with air and placing a platinum-platinum-10 pct rhodium thermocouple in the position previously occupied by the crucible; the temperature of the majority of the runs was much closer than the deviation specified above. The couple was checked against a standard couple which had been calibrated at the gold and palladium points, and against a Bureau of Standards couple. The carbon monoxide atmosphere was prepared by passing COz over granular graphite at about 1200°C. It was purified by bubbling through a 30 pct aqueous solution of potassium hydroxide and passing through ascarite and phosphorus pentoxide. The train and connections were all glass except for a few butt joints where rubber tubing was used for flexibility. The rate of gas flow was 25 to 40 cc per min. As atmospheric pressure prevailed in the furnace, the pressure of carbon monoxide was only slightly higher than the partial pressure thereof in the bosh and hearth zones of a blast furnace—by virtue of the elevated total pressure therein. Simultaneous samples of blast-furnace metal and slag were taken for these remelting experiments. The composition of each is given in the first line of Table I. There is considerable uncertainty as to the significant temperature in a blast furnace at which to compare experimental results. This uncertainty arises not only from lack of temperature measurements in the furnace, but also from lack of knowledge of the zone where the slag-metal reactions occur. (Do they occur principally at the slag-metal interface in the crucible, or as the metal is descending through the slag, or even higher as slag and metal are splashing over the coke?) The known temperatures are those of the metal at cast, which averages about 2600°F, and of the cast or flush slag, which is usually about 100°F hotter. To bridge this uncertainty, remelting temperatures were chosen as 1400°, 1500" (2732°F), and 1600°C. For the time series the duration of remelt was 1, 2, 4, 8, 17, or 66 hr; crucible and contents were quenched in brine. The addition series were quenched by rapidly transferring the crucible and contents from the furnace to a close-fitting copper "mold." Of incidental interest here is the fact that the slag wet the crucible

Jan 1, 1953

By S. T. Hall

The authors have previously described a method of enhancing the magnetic susceptibility of pyrite by a mild alkaline oxidative pressure leach (Hall et al, 1985). This finding was successfully applied to enhance the magnetic desulfurization of an Eastern Canadian coal (Hall and Finch, 1984). This paper reports on enhancement of the magnetic susceptibilities of iron-containing sulfides (arsenopyrite, chalcopyrite and marcasite) upon similar treatment. It also explores the application of this pretreatment in the magnetic separation of fine sulfides from oxides and other sulfide minerals. In the latter case galvanic interference effects have a serious impact on the potential use of this method.

Jan 1, 1985

By J. M. Stuve

In this Bureau of Mines investigation, the low-temperature heat capacities of polycrystalline phases corresponding to the sulfide compounds CoSO?89' CoS1?33, and CoS2 were measured by adiabatic calorimetry within the nominal temperature range 5 to 300 K. The derived absolute entropies S298 were 10.36±O.02, 12.96±O.03, and 16.31±O.03 cal?mol-1?K-l, respectively, assuming third-law behavior. In addition, the standard enthalpy of formation 8Hf298 of CoSO?89 was determined by bromine solution calorimetry. The derived value of 8Hf298 was -50.63±2.1 kcal?mol-1, based on the 8Hf298 of Co0. This result is considerably more negative than previously published formation values based on high-temperature gas equilibrium studies.

Jan 1, 1985

By D. R. Derry

"IT WOULD TAKE a braver man than I to try to forecast the future of mining exploration far into Canada's second century. Even to look ahead ten or twenty-five years we must review the figures of the fairly recent past -and I have found this quite a time-consuming but interesting job -in order to find trends and project them into future years. The trends to which I will refer are: firstly, the annual expenditure on exploration and its relation to value of output; secondly, the discovery rate and its relation to production initiations; and thirdly, the methods by which discoveries have been, and will be, made. Exploration Expenditures Figures on the annual expenditure on mining exploration in Canada have been collected and published for some years by the Do-minion Bureau of Statistics. These have some unavoidable limitations; e.g., in the varying definition between one company and another of what comprises ""Exploration"" and in the difficulty of getting complete returns. However, although the actual figure for a given year may be subject to question, I believe that the relative figures from one year to another are reasonably reliable. There is also a lapse of time between the collection of data and publication -the last published figures are for the year 1963. In bringing the figures up to date to 1966 I have canvassed eight of the larger mining and exploration companies and obtained their figures for 1963 to 1966 inclusive, and then averaged these for each year and applied the progression to the 1963 figures."

Jan 1, 1968

By Bertrand L. Johnson

Before 1914 , Chile , because of her extensive resources of natural nitrates , practically monopolized the world markets for one of the leading fertilizer materials . Since nitrogen also is an important war material , constituting in fact the principal ingredient in many high-powered explosives , the World War and the widespread insistence upon national self- sufficiency for war materials brought about the development of nitrogen fixation plants in all of the larger countries . The production of by- product ammonia from gas and coke plants was likewise stimulated . As a result , Chile , even after the ocean lanes were reopened , was forced to fight for her lost markets . Since the world capacity to produce is still far in excess of annual consumption , the competition between natural and synthetic supplies has been keen and prices have fallen below pre-war levels . Chile has recently succeeded in unifying her industry , utilizing the most efficient process now in operation, and the Government is a partner in the new company that will take over all of the present producing companies . These developments place Chilean nitrate of soda , in a much more favorable position among the markets of the world . More intense competition will undoubtedly follow and , in order that those interested may become familiar with the fields upon which the nitrogen conflicts of the near future may be waged , the following general summary of the nitrogen industry has been prepared .

Jan 1, 1931

By P. F. Sands

This U.S. Bureau of Mines report reviews the state of the art in blind pneumatic stowing of backfill in voids in abandoned coal mines. It contains a short history of the development of pneumatic equipment in mining and four recent case histories of blind pneumatic stowing. Limitations of pneumatic stowing in terms of equipment wear, costs, backfill material, and methodology are discussed, and some new procedures and designs are reviewed. A bibliography covering pneumatics in mining is included also. This report provides background for the preparation of a Bureau test program in which the variables affecting the efficiency of pneumatic backfilling will be studied using a full-scale surface test facility.

Jan 1, 1990

By J. Forster, C. A. Pickles, Mackowiak. K.

The future development of nickel laterite deposits is crucial with regards to satisfying impending nickel demands. The commercial implementation of new hydro/pyrometallurgical processes in recent years has led to significant improvements in the extraction of nickel from the laterite ores. One potential alternative pyrometallurgical processing route would be to selectively reduce the nickel and produce a concentrate with nickel contents similar to those attainable in the conventional flotation of sulphide ores. However, even bench scale studies have not yet been able to produce a high grade (>15% nickel) concentrate from a low grade laterite ore. The present research involved the microwave vacuum reduction roasting of a nickel laterite ore to yield a high grade concentrate, rich in nickel. Firstly, the effects of temperature and pressure on the nickel grade and recovery were investigated using a thermodynamic model. Secondly, briquettes containing a mixture of charcoal and a low grade silicate nickel laterite ore were reacted in a microwave vacuum system. The experimental variables studied were the input microwave energy, pressure and absorbed microwave power. Thirdly, the ferronickel in the reacted briquette was concentrated by magnetic separation and nickel grades of up to 21% could be achieved.

Jan 1, 2015

1. Mining directory The mining directory, 1990. Mines and mining equipment companies worldwide. Don Nelson Publications Limited (P.O. Box 193, Barnet, Herts EN4 BLP, England).2. Mintek reports The following reports are available from Mintek, Private Bag X3015, Randburg, 2125 South Africa. They are available at R25 (plus R3,25 GST) per copy to South African addressees, and US$25 per copy (including airmail postage) to addressees elsewhere. There is also an annual-subscription scheme for reports - R400 locally (plus R52 GST) and US$400 (including airmail postage) abroad. The subscription covers al the unrestricted reports published between 1st April and 31st March of successive years, which usualy amount to between 20 and 30. Report M392 Computer programs for optimization by the modified simplex method, by G.L. Moore. Sep. 1989. 25 pp. R25 + R3,25 GST in South Africa; US $25 elsewhere. Report M393 The preparation and certification of fourteen South African silicate rocks for use as reference materials, by E.J. Ring. Sep. 1989.21 pp. R25 + R3,25 GST in South Africa; US $25 elsewhere. Report M395 The separation of trace elements in high-purity rhodium and iridium materials, by R.V.D. Robet and S.M. Graham. Nov. 1989. 10 pp. R25 + R3,25 GST in South Africa; US $25 elsewhere. 3. Publications from Trans Tech The publications listed in this section are available at the prices given from Trans Tech Publications, P .0. Box 1254, D-3392 Clausthal-Zelerfeld, West Germany. Handling of bulk solids. Theory and practice, by P.A. Shamlou. 1988. 200 pp., US$ 59.50. Acoustic emission lmicroseismic activity in geologic structures and materials, by H.R. Hardy and F.W'. Leighton. Vol. I: 1977, 490 pp., US$45.00. Vol. 11: 1980, 500 pp., US$45.00. Vol. Il: 1983, 680pp., US$6O.00. Vol. IV: 1989, 720pp., US$ 75.00. Open pit mine design models. An introduction with FORTRANI77 programs, by E. Alaphia Wright. Early 1990, approx. 200pp., US$75.00. Bucket wheel excavator, by W. Durst and W. Vogt. 988, 450pp., US$118.00. Continuois-surjace mining, by T.S. Golosinski and F.G. Boehm (eds.). 1987, 720pp., US$128.00. Mining-science and technology. 1987, 1430pages, US$ 118.00. Practical handbook for underground rock mechanics, by T.R. Stacey and C.H. Page. 1986, 150pp., US$ 38.00. Professional users handbook for rock bolting, by B. Stilborg. 1986, 150pp., US$38.00. The lighting of underground mines, by D.A. Troter. 1982, 220pp., US$48.00. Elements of hydraulic coal mine design, by M.L. Jeremic. 1982, 16Opp., US$38.00. Continuum theory of rock mechanics, by Cs. Assonyi and R. Richter. 1979, 365 pp., US$ 58.00. Shear and bond in reinforced concrete, by G. Florin.1980, 86 pp., US$ 24.00. Theory and design of surface structures: slabs and plates, by G. Florin. 1980, 222 pp., US$ 24.00. Mineral processing laboratory manual, by A.-Z. Abouzeid. January 1990, approx. 200pp., US$48.00. Weighing and proportioning of bulk solids, by Hendrik Colijn. 2nd ed. 1983, 4OOpp., US$60.00. Solid-liquid flow. Slurry pipeline transportation, E.J. Wasp et al. 1977, 240pp. US$ 58.00. Optimum pipe size selection, by C.B. Nolte. 1978, 304 pp., US$ 60.00.Field instrumentation in geotechnical engineering, T.H. Hanna. 1985, 854pp., US$98.00. The 1990 yearbook and directory. Powder and bulk solids handling and processing. 1989/90, approx. 300 pp., US$ 124.00.

Jan 1, 1990

By E. A. Nesbitt

THE important permanent-magnet alloys 15 years ago contained carbon and depended upon it for their permanent- magnet properties. In recent years great, advances have been made in a number of new alloys substantially free of carbon. These include Remalloy,l an alloy of iron, cobalt, and molybdenum, the various iron- nickel-aluminum alloys of the Mishima2 type, and the more recent Alnico V3 in which the best properties are developed by heat-treating in a magnetic field. The Mishima and the Alnico types of alloys are very brittle and after casting must be ground to size. This article describes a permanent-magnet material4 that can be machined as cast, and when handled with some care can be .rolled to thin sheet and drawn to fine wire. Optimum magnetic properties are developed by a simple heat- treatment, and at this time the ductility A of the alloy disappears. If the cast alloy is heat-treated without cold-working the magnetic energy product is about 1.0 X 106. This material is called Vicalloy I (pronounced vicalloy, V for vanadium, I for iron, and C for cobalt). When the alloy is first hot-worked and then considerably reduced in area by cold-swaging, drawing or grooved rolling, it is found that after heat-treatment the magnetic energy product measured in the direction of previous extension can be increased to 2.0 to 3.5 X l06. These higher values have been obtained only after reductions in area of 75 to 95 per cent, and since the material hardens considerably during working, the reduction ordinarily can be accomplished only in fine wires, although larger sizes can be reduced by the use of powerful machinery. When the material has been cold- worked in such a manner as to improve its energy product substantially, it is called Vicalloy II. Commercial use of Vicalloy has been made in the recording of speech. Tape 0.002 by 0.050 in. has been found superior in quality to all others tried, and is now used in the Western Electric Mirrorphone In a variety of forms Vicalloy I or II is useful in many laboratory instruments, and in experiments in which the sizes and shapes required cannot be obtained with the other more brittle permanent-magnet materials. In 1936, during a study of other age- hardening magnetic systems, it occurred to the author that some of the iron-cobalt-vanadium alloys might be suitable for permanent magnets. The proportions of iron, cobalt, and vanadium were varied and a range of alloys of particular interest was found, as shown by the indicated area in Fig. I. The limits of this range of com- position are 30 to 52 per cent iron, 36 to 62 per cent cobalt, and 4 to 16 per cent vanadium. The compositions indicated by points outside this area were also tested. PREPARATION AND PROPERTIES OF VICALLY I The alloys were usually cast in graphite molds into bars ¾ in. in diameter and

Jan 1, 1946

By John Ward Smith

This paper describes and evaluates a method that the Federal Bureau of Mines used to determine the ultimate composition of the organic material in 10 samples of oil shale from the Mahogany zone of the Green River formation in Colorado and Utah. Since interest has centered on the Mahogany zone, the richest section of the deposit, these 10 samples were chosen to provide a broad representation of this zone with the objective of obtaining generally valid ultimate composition values. The most probable organic composition for the Mahogany zone and the 95-percent confidence limits for each component average (in weight-percent of organic material) are: Carbon 80.5 ± .4 Hydrogen 10.3 ± .1 Nitrogen 2.4 ± .1 Sulfur 1.0 ± .1 Oxygen 5.8 ± .5 As only minor variations in composition were observed, the organic material of this particular bed is quite similar over a wide geographic area.

Jan 1, 1961

By G. L. Humphrey

Although thermodynamic data for ferrous oxide are among the most important in extractive metallurgy, adequate values have not been available until quite recently. The older data suffered not only from the usual experimental difficulties but especially from lack of the knowledge that ferrous oxide of stoichiometrical composition does not exist as a single, thermodynamically stable crystalline phase under any circumstances. This paper reports new experimental data on the heat of formation of ferrous oxide by two methods (combustion calorimetry and solution calorimetry), employing material of unequivocal composition. The results are compared with values obtained from data for the hydrogen reduction, carbon monoxide reduction, and disproportionation reactions of ferrous oxide, and a best value is selected. A table of heat and free energy of formation values of ferrous oxide to 2,000°K is given. These values are combined with available data for water, carbon monoxide, and carbon dioxide to obtain theoretical heats and free energies of reduction corresponding to the selected heat of formation. Hydrogen and carbon monoxide reduction equilibria are compared, and the differences in trend with temperature and the percentage utilization of the reductants are considered.

Jan 1, 1952