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THE British Industrial Fatigue Research Board has issued its annual report covering the year 1925, and a nine-page review of it, by George E. Shepard, was published in this country in the November, 1926, Bulletin of the Society of Industrial Engineers. The report gives results of three different investigations, all of which indicate that rest-pauses, where the spells .of work are 41/2 hr. long or more, not only increase the contentment of the workers, but often bring about an increase in output. A report on the physiology of ventilation is about to be published, and one on the theory of ventilation has been issued. These seem to add but little to the work being done in this country by the Bureau of Mines and the American Society of Heating and Ventilating Engineers. Other studies made are on atmospheric conditions in cotton weaving, on lighting in composing rooms, on repetitive work, the teaching of muscular skill, the energy expenditure in heavy work, the metabolic processes involved in violent exercise, the relation between oxygen intake and lactic acid in the blood, and fatigue in localized groups of muscles. Most of this material is intended for advanced workers in these fields, but will be of interest to engineers who desire to keep up with cur-rent progress in the determination of the facts involved in fatigue resulting from industrial work.

Jan 2, 1927

By D. D. Hawat

The locations of potential reserves of chromite ores throughout the world are discussed. Reference is made to the marked changes in international trade in chromite ores during the past ten to fifteen years, and to the change in locality of the production of ferochromium aloys, which is curently largely carried out in the country of origin of the ores. The influence of these changes has been very profound in South Africa, which has the largest smelting capacity and the largest production of ferochromium aloys in the world. A proportion of South African ore is stil exported to meet the demands for the production of chromium chemicals and refractories, including a large tonnage of foundry sands. Ferochromium smelters in South Africa have a capacity of virtualy 1 Mt of aloy per annum. Nearly al this development has taken place since the introduction of the argon-oxygen decarburization (A.O.D.) process for the smelting of stainless steels. Formerly, expensive Iow-carbon ferochromium aloys were required as raw materials, but the AO.D. process, which is being used world wide, permits the use of high-carbon ferrochromium, the main product of the smelters in this country. The production in South Africa of chromium-containing corrosion- and heat-resistant steels is stil on a relatively smal scale, but serious atention is being paid to the exploitation of low-carbon weldable feritic chromium steel.

Jan 1, 1986

1. Reviews A concise world atlas of geology and mineral deposits, by D. R. Derry. London, Mining Journal Books, 1980. (Reviewer: B. C. Alberts) The geology of the Western Cordillera of northern Peru, by various authors. London, Institute of Geological Sciences, Overseas Memoir 5. (Reviewer: C. E. Feather) 2. New books Influence of diffusion coatings on the strenth of steel, by G. V. Karpenko, V. I. Pokhmurovskii, V. B. Dasilov, and V. S. Zamikhovskii, second revised and updated edition by A. Aladjem. Aedermannsdorf (Switzerland), Trans Tech Publications, 1979. 200 pp. Sw. Fr. 68.00. Mechanical and corrosion properties, by G. S. Ansell, P. Haasen, J. Weertman, D. J. Fisher, U. Gramberg, and F. W6hlbier (editors). Heat-resistant and refractory steels, by K. L. Lanskaya. Aedermannsdorf (Switzerland), Trans Tech Publications, 1979. 266 pp. Sw. Fr. 86.00. Hardening of metals, by P. Feltham (editor). Aedermannsdorf (Switzerland), Trans Tech Publications, 1980. 316 pp. Sw. Fr. 78.00. Precious metals The 6th International Precious Metals Conference will be held in Newport Beach, California, from 7th to 11th June, 1982. Strata mechanics A symposium on Strata Mechanics is to be held in Newcastle-upon-Tyne from 5th to 7th April, 1982. Over the past thirty years, mining of coal and stratified mineral deposits has become increasingly capital-intensive, and the level of investment demanded by modern methods has led to demands for improved assessment of their likely performance.

Jan 1, 1981

By John W. Cabot

The fact has long been known, that the temperature at which steel is made and cast bears a very important relation to the molecular condition of the cast ingot. But until quite recently this fact has not received the consideration which its importance seems to justify. That the ingots from a very " hot " blow in the Bessemer converter, for instance, would not roll as well as those made at a lower temperature, was observed very early in the development of the process; but the further investigation of the effects of varying temperature from "hot" to "cold," has not been carried out with that degree of fulness which has been accorded to the effects on the rolling of the chemical elements, and other conditions in the manufacture. In the following pages will be presented the results of an investigation of this subject, undertaken with the view of determining how far the influence of temperature extends, through how great a range its effects can be traced, and what temperature in the making and casting will give the best results in the rolling of the ingots. In the series of observations forming the basis for the conclusions arrived at, while it was not possible to get the full chemical analysis of every heat considered, a complete record of each, in other details, was made, and a large number of these were averaged together to

Jan 1, 1886

By August Wendel

IT is a well-known fact to all Bessemer steel manufacturers using a blooming mill, that ingots show large cracks in the first few passes of the rolls, which, in the following ones, do not always roll up satisfactorily. This deficiency in the quality of the product is generally called " red-shortness," though, in the writer's opinion, mostly unjustly so. Different explanations for the said peculiarity are given by the leading authorities, each works selecting one element as a special scape-goat for the inferior quality of the ingot. The sulphur is generally first charged as being the principal cause of all mischief in this direction ; then, after ascertaining that sulphur is not higher than the average, and sometimes lower in the very worst heats, silicon has to bear its share of abuse. How and why silicon should affect the working qualities of the metal, the writer could never precisely learn, but is convinced that the doctrine of its pernicious influence is an established one with many. In cases where silicon failed to explain everything, resort was taken to calcium, aluminum, and some other known or unknown elements, without settling the difficulty; and lastly, when the skill of the chemist became exhausted, " practical men " came to the same conclusion, which many leading blast-furnace managers had arrived

Jan 1, 1876

By Horace Pops, L. L. Isaacs

SOLID-STATE transformations at low temperatures are frequently studied by optical metallography. Greninger and ooradian' and Hull and Gar-wood2 have examined the martensitic-type transformations in 0-phase Cu-Zn alloys during continuous cooling below room temperature. The lowest range of temperatures in the apparatus described by these investigators is limited to approximately 110°K. Present studies of reversible first-order phase transitions near liquid-helium temperatures have necessitated the design of a new cold-stage cryo-stat for optical metallography. The features of interest of this instrument are as follows: a) temperatures down to 4.Z°K are obtainable; b) the specimen is always under vacuum, thereby avoiding the condensation of moisture; c) specimens can be rapidly cooled or heated at varying rates, thus permitting studies of transformation hysteresis. Fig. 1 shows the details of the cryostat. All major parts are made of type 304 stainless steel. Both helium and nitrogen cans are Heliarc-welded to the helium filling tube, permitting the use of a common shielding can. Hence, the over-all weight and the area of the evacuated surface are mini- mized. The copper sample holder is screwed into the bottom of the helium can. To assure good thermal contact between the sample holder and the refrigerant, an indium ribbon is placed on the threads

Jan 1, 1964

By Laurentiu Nastac

"The importance of investigating solute redistribution during the unidirectional solidification of multi-component alloys is broadly discussed in the literature. A previously developed analytical model that was experimentally validated for Al-Cu, Sn- Bi and Fe-Si dilute binary alloy systems is used in this article to study in detail the solute redistribution, the liquid/solid interface stability based on an extended transient constitutional undercooling criterion and the size of the initial transient region during the unidirectional solidification of Ti-6-4 and Ti-17 alloys. A comparison between Ti-6-4 and Ti-17 alloy systems with respect to interface stability and the size of the initial transient region is also provided. The effective partition coefficients of the alloying elements in these alloys were determined based on specially designed experimental measurements.IntroductionThe importance of investigating solute redistribution during alloy solidification is broadly discussed in the literature [1-5]. One of the relevant applications of this study would be the mathematical modeling of equiaxed and columnar solidification of multicomponent alloys. This includes the instability of the solid/liquid interface. There are several mass and heat transfer processes that involve the calculation of solute redistribution during directional solidification such as industrial directional solidification processes, continuous casting, remelting processes, Czochralski crystal growth technique, floating zone techniques, etc."

Jan 1, 2012

By August Wendel

It is a well-known fact to all Bessemer steel manufacturers using a blooming mill, that ingots show large cracks in the first few passes of the rolls, which, in the following ones, do not always roll up satisfactorily. This deficiency in the quality of the product is generally called "red-shortness," though, in the writer's opinion, mostly unjustly so. Different explanations for the said peculiarity are given by the leading authorities, each works selecting one element as a special scapegoat for the inferior quality of the ingot. The sulphur is generally first charged as being the principal cause of all mischief in this direction ; then, after ascertaining that sulphur is not higher than the average, and sometimes lower in the very worst heats, silicon has to bear its share of abuse. How and why silicon should affect the working qualities of the metal, the writer could never precisely learn, but is convinced that the doctrine of its pernicious influence is an established one with many. In cases where silicon failed to explain everything, resort was taken to calcium, aluminum, and some other known or unknown elements, without settling the difficulty; and lastly, when the skill of the chemist became exhausted, " practical men " came to the same conclusion, which many leading blast-furnace managers had arrived

By A. J. Van Rensburg, N. B. Strydom, C. H. Van Graan

The design, construction, and use of a practical ice-jacket for miners by N. B. STRYDOM, Ph.D. (Illinois) (Fellow), D. MITCHELL, Ph.D. (Rand) (Member), A. J. VAN RENSBURG, M.Sc (Poteh) (Visitor), and C. H. VAN GRAAN, M.Sc (Pretoria) (Visitor) Microclimate suits have been shown to be very effective in decreasing physiological strain in hot, wet environments, thus enabling men to work without risk in areas that would normally carry a high risk of heat stroke. In this paper, some design considerations in the development of the frozen jacket are described. Water complied with most of the desirable properties required of a coolant material for use In a microclimate suit. The Human Sciences Laboratory has developed a jacket in which ice is used as the coolant and which is designed according to the most acceptable anthropometrical characteristics. The jacket consists of an inner poncho-type waistcoat containing 28 water compartments. Over this is worn an insulating jacket, which minimizes warming of the coolant by the environment. Suitable refrigeration units have been developed to freeze the jackets underground. Laboratory tests have shown that these jackets are effective for about 2,5 hours, Irrespective of the wet-bulb environment, when men are working at a moderate rate. Jackets should, however, be used only in environments in which the wet-bulb temperature is in the range of 32,S0 to 35,S °C.

Jan 9, 1974

By D. J. Bosman

Rapid fouling of condenser tubes in underground refrigeration plants is a frequent occurrence. It leads to low heat transfer efficiencies, with consequent serious reduction in capacity and increase in the horse-power requirement of the units. High pressures develop in the condensers, and frequent cleaning of the tube bundles is required. The cleaning operation takes up to 8 hours and in some cases results in significant loss of production. One of the possible causes of fouling is deposition of scale, but this can be readily overcome by controlling the concentration of the water. When water evaporates, the dissolved solids remain behind; thus evaporation increases the amount of dissolved solids per unit volume. If half the original volume evaporates, the concentration of the dissolved solids is doubled and the water is said to have a 'concentration' of two. Concentration may be controlled by regulating the amount of water allowed to bleed from the system. The actual concentration value required is a function of the chemical analysis of the circulating cooling water. In one instance, where the problem of scale formation had been eliminated, fouling still persisted, and the possibility of excessive quantities of dust in the re-circulating water was investigated. A dispersing reagent was added to the condenser cooling water as a means of preventing sludge deposition in the condenser tubes. As shown by curve A in Fig. 1 the reagent addition did not decrease the rate of fouling.

By P. B. Demarsh

"Location: - On highway 59, 17 miles east of Val d 10r near junction of Montreal highway in Northwestern Quebec.Life; - Started production 1952, ceased 1965.Ore: - Pyrite, chalcopyrite and small amounts of free gold and goldsilver tellurides in narrow quartz-carbonate-tourmaline veins in granodiorite. Specific gravity 2, 70.Capacity: - 700 tons daily Bevcon ore supply, l 000 tons daily when custom ore available.Assay: - Heads 0 .140 oz. per ton; tails 0. 009 per ton; extraction 92.5%.Grind: - 75% minus 200 mesh at 700 tons; 68% minus 200 mesh at 1000 tons. Detention time 28 hours and 21 hours respectively.Treatment: - Cyanidation process.Reagents: - Per ton. Aero Cyanide (NaCn) 0, 50; crushed unslaked lime 1. 75; zinc 0. 03; litharge 0. 10; steel consumption 2. 25.Water: - Pumped from land-lock spring fed lake l 1/2 miles distant.Cost: - Per ton. Crushing 0. 13; grinding 0 .32; filtration 0. 07; cyanidation 0.14; miscellaneous 0.29; total 0.95.Power: - Hydro-electric, 25 cycle, 12, 000 volts reduced to 550 volts.Labour: - Predominantly French Canadian, nucleus English Canadians.Tailings: - Impounded low lying pond.Personnel: - 15 including supervision.Flow sheet: - Canadian Mining Manual l 9 5 6 .Building: - Wood truss construction: 3/ 4 in. siding, ten test and 1/ 4 in. transite outside. Corrugated galvanized iron roof. Ground level foundations. Internal self induced heating. Wood stave tank equipment."

Jan 1, 1966

By Ana Bohé

Nowadays, Gas-solid processes are widely used in the industry. The chloration and carbochlorination of metallic compounds are some of this kind of non catalitic heterogeneous reactions. In particular those related with extractive metallurgy of refractory elements (Zr, Ti, Nb, Ta, RE, etc). The development of materials to be used in reactors at elevated temperatures and with high corrosion performance, enhance the application of this kind of processes. Although they are currently carried out in the production of many comodities, the mechanism of most of them are yet not well understood. The present work is a deep discussion on the most important aspects to take into account for determining the mechanism of gas- solid reaction, and those criteria fulfil in this analysis were applied to chlorination and carbochlorination examples. The microstructural characteristic of solids, the mass and heat transfer phenomenon, the adsorption and desorption of gaseous species on active surface, surface diffusion processes and chemical elementary steps, which are the mainly contributions to the mechanism of these reactions were analysed. Furthermore, the effect of them on the reactivity of solids and the control step of the reactions were determined. The application of catalitic mathematical models to this kind of reaction and the modification for the better interpretation of experimental results is also undertaken. The most appropriate experimental procedures for following these reactions and the microstructural characterization techniques needed to be use in each case, there limits and applicability are also indicated.

Jan 1, 2006

By W. W. Coblentz

THE constants in question pertain to the total radiation and the spectral radiation of a uniformly heated enclosure, or so-called black body. These constants have been determined for the range within which temperatures can be measured with thermocouples. Conversely, using these constants and suitable instruments, such as an optical pyrometer, for example, it is possible to determine temperatures far above the range attainable with the most refractory thermocouples. The formula of Stefan Boltzmann for expressing the total radiation of a black body is R = kT4 in which k is the coefficient or "constant" under discussion. In view of the fact that total radiation pyrometers are usually calibrated on an arbitrary scale, there is no great demand for an exact value of the coefficient of total radiation in absolute value. However, it is intimately connected with the constant of spectral radiation; hence, an accurate determination of the constant k gives a check on the constant of spectral radiation. The distribution of radiation in the spectrum of a black body is represented by Planck's equation, E? = C1?-5 (e c/?T - 1)-'. The spectral radiation constant c, in this formula, is useful in optical pyrometry and in establishing a high temperature scale. The numerical value of the constant c has been determined in the range of temperatures measurable with thermocouples and, also, by extending the temperature scale to higher temperatures by means of total radiation measurements.

Jan 8, 1919

By Wenqing Qin, Yunfan Wang, Ximei Luo, Fen Jiao

In order to investigate the effect of nanobubbles on adsorption of surfactant on mineral surface, the nanobubbles on the surface of calcite with -37µm fraction in the sodium oleate system were controlled by pressurization and decompression to mixing vessel. Subsequently, the adsorption amount of sodium oleate on the surface of calcite were detected by ultraviolet spectrum at different stirring times and different pressures. At the same time, the nanobubbles on the calcite surface were imaged with atomic force microscopy (AFM). In addition, a homemade vacuum Hallimond tube device was used for the flotation of single mineral, and the grade and recovery of minerals in concentrate was used to determine the influence of the nanobubbles on flotation. The experimental results showed that a large number of nanobubbles were found on the calcite surface by AFM under the dissolved oxygen difference (DOD) condition of -4 mg/L. And a large difference in adsorption capacity of sodium oleate on the surface of calcite was observed under different air pressure conditions. It indicated that the ambient pressure had a certain effect on the adsorption of sodium oleate on the calcite surface, and this effect did not depend on the constant low pressure or constant normal pressure, but depended on the changing process of pressure. The single mineral flotation experiment results indicated the recovery of calcite under decompression condition (formation condition of nanobubbles) was 1.5-2 times that under constant normal pressure, and the flotation time is much shorter. Moreover, the recovery under constant normal pressure was greatly influenced by flotation time. In this paper, only one aspect of the effect of nanobubbles on mineral flotation was preliminarily explored. It was confirmed that after vacuum-pumping, the adsorption of sodium oleate on calcite surface could be increased, the flotation time also was greatly reduced and the recovery of calcite was increased.

Jan 1, 2018

By Eric Jette

The nickel-chromium alloys form the base f for many industrial heating alloys, so that this system is of considerable practical importance. The literature on these alloys, however, contains much conflicting evi-dence, not only regarding the solubility limits of the terminal solid solu-tions at different temperatures but even regarding, the number of phases existing in the system. Part of the difficulty undoubtedly arises from the fact that chromium of sufficiently high purity has been available only during the last few years. A second and possibly even more impor-tant difficulty arises from the ease with which chromium reacts with silicon and carbon compounds and the atmosphere to form silicides, carbides, nitrides and oxides. Pilling and kihlgren1 in 1929 reviewed the existing scanty information. They did not consider the diagram by which they summarized the various bits of information to be entirely satisfactory. Matsunaga2 investigated the system by thermal analysis, microscopic examination and other means. Electrolytic nickel of 99.9 per cent purity and thermit chromium containing 0.30 per cent al, 0.40 per cent fe, 0.25 per cent si and 0.04 per cent c were used. A tammann furnace with hydrogen flowing through it was used for melting. Sekito and matsunaga3 reported an x-ray, investigation presumably on these same

Jan 1, 1934

By Maurice Rey

The copper segregation process is designed to concentrate oxidized copper ores or mixed sulfide-oxide copper ores which are refractory to normal and cheaper mineral dressing or leaching processes. Such ores contain copper silicates or highly disseminated copper minerals in a gangue not entirely free from limestone or dolomite. Concentra¬tion by flotation is, under these circumstances, not possible and the acid-consuming constituents do not permit acid leaching. A high temperature treatment at 700-800°C, in the presence of a small amount of sodium chloride and of finely divided carbon, concentrates the copper into easily floated metal by a kind of reducing chloridizing roast. The sulfides, if present, are either oxidized in the heating stage and react like oxides or float with the metallic copper in the flotation step. The ores which have the aforementioned characteristics and which are high grade enough to pay for the treatment are scarce, so that the process has only a limited application. Theory of Copper Segregation Sodium chloride, reacting with water vapor and the acid gangue constituents, produces hydrogen chloride which reacts with the copper minerals. The copper is volatilized as cuprous chloride and immedi¬ately reduced on the coal particles by hydrogen emanating from the volatile matter of the coal and from the water-gas reaction. Hydrogen chloride is

Jan 1, 1985

By D. B. Swanepoel

Hulamin Rolled Products (Ltd) developed a high Mn and Si containing alloy, EN 4017 as a scrap consuming alloy from the waste generated in producing their range of clad products for brazing of inter alia automotive heat exchangers. The multifaceted composition of this alloy (Al -1.2 wt% Si -1.1 wt% Mn -0.2 wt% Mg-0.26 wt% Cu) suggested that it might display some degree of strengthening via precipitate formation of the Mg2 Si-types. The aging isotherms constructed showed that EN 4017 with 0.19% Mg reached a lower peak strength (YS~210 MPa and UTS~260 MPa)compared to the EN 4017 material with 0.43% Mg (YS~270 MPa and UTS~325 MPa). The higher Mg variant of EN 4017 was comparable with the age-hardenable reference alloy EN 6061. Selected area electron diffraction (SAED) studies proved that the microstructure of age hardened EN 4017 contained a combination of ß', ß" and U2 phase after being aged at 175ºC for 65 h. The general microstructure contained precipitate free zones as well as grain boundary Si films, although these did not lead to significant embrittlement. The role of Mn dispersoids in the fracture mechanism of 4017 is also discussed. The article will compare the behaviour of EN 4017 with that EN6061. Keywords: Age-hardening, dispersoids, magnesium silicide, precipitate free zones

Jan 1, 2009

By S. K. Kawatra, T. C. Eisele

Coal-cleaning operations commonly produce a fine-waste stream containing a considerable amount of coal. The recovery of this coal is normally not economical because the coal is mixed with large amounts of difficult-to remove clay slimes and is often heavily oxidized or contaminated. Conventional froth-flotation machines cannot, in a single flotation stage, produce an acceptable product from such material, and even flotation columns often have difficulty cleaning this type of feed. A new type of flotation column was designed specifically to deal with these problems, and a column of this design was installed and tested in a coal-cleaning plant in Ohio. The feed coal tested was the plant&apos;s tailings-thickener product. The coal was 80% -176 µm and had a heating value of 8401 Btu/ lb. The coal contained 39.8% ash, as fine clay, and 2.83% total sulfur. Because previous attempts at conventional flotation of this type of material had been abandoned, plant personnel believed that the coal was too heavily oxidized and contaminated for flotation to be effective. However, by using the new column it was possible to recover up to 85% of the calorific value in a product containing < 11 % ash, and it was possible to recover 60% of the calorific value in a product containing <8% ash. In addition, the bulk of the pyritic sulfur was also rejected from the coat.

Jan 1, 1996

By Francis M. Walters, Irwin R. Kramer

The substitution of cobalt for part of the nickel in Invar was found by P. H. Brace1 to lower the coefficient 01 expansion. Scott1 extended the use of cobalt to alloys of higher inflection temperatures. Such alloys have a larger temperature range of low expansion than those without cobalt, and their use up to 400&apos; or 500°C. offers decided advantages in certain applications. However, it has been found that the iron-nickel-cobalt alloys are not stable in this temperature range. Experimental Methods Two methods were used in studying the stability of the low-expansion iron -nickel-cobalt alloys. Dilatometer specimens were held at 480°C. for 9 months and the change in expansion characteristics was dctcr- mined. Filings were held for about 2 months at various temperatures and the change in structure was determined by X-ray diffraction. As shown by Table I, the alloys studied covered a wide range in nickel plus cobalt content (which determines the inflection temperature) as well as some variation in the ratio of nickel to iron (which controls the temperature of the gamma to alpha transformation). Included also are alloys containing carbon and vanadium, carbon and titanium and three with various amounts of copper. The alloys were melted in a high-frequency induction furnace with a magnesia crucible, using ingot iron, electrolytic nickel and commercial cobalt. Fifteen-pound heats were cast into iron molds after deoxidizing with silicon, or

Jan 1, 1942

EDMUND NEWTON, Minneapolis, Minn. (communication to the Secretary?).-In discussing the question of the deoxidation of steel and material suitable for performing this function at the end of the heat, it would seem logical also to include the question of prevention of oxidation in the steel or the formation of iron oxide, FeO. I refer to the use of manganese in the basic open-hearth and basic Bessemer processes. The advantages of high manganese in pig iron for these processes have evidently been clearly understood in Germany for a number of years, although little has been written in regard to the exact manner in which the benefits are obtained. In this country, while we make no steel by the basic Bessemer process, our basic open-hearth process is becoming more and more important. Until 10 years ago, in this country, manganese in the pig iron for this process was considered of little value and by many writers it was spoken of as a disadvantage. During the past 10 years, however, in certain parts of the United States, higher contents of manganese in basic pig have been used with considerable success, although there is apparently nothing in our technical literature to show the reasons for this trend. A German book, "The Basic Open-Hearth Steel Process" by Carl Dichmann does, however, offer an explanation. Dichmann says that if the charge for either of the above-mentioned processes contains 3 per cent. of manganese or above, satisfactory steel.

Jan 6, 1917