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By Fernanda da Silva Machado

Em um mundo de recursos naturais decrescentes, com a intensificação das indústrias automatizadas de todos os tipos (I4) e contínuo aumento da população, é necessário desenvolver melhores caminhos para a geração e distribuição de riquezas. Uma das alternativas para este objetivo é o conceito da Economia Circular. Este artigo apresenta um exemplo focado na intensificação do uso de resíduos de biomassa na produção integrada de aço exclusivamente baseada na combinação de reatores industriais existentes em um layout que favorece o conceito da economia circular. O ferro também é obtido do processamento tradicional de sucata, reprocessamento de resíduos de ferro e óxidos de ferro, como a escória, pequenos óxidos de ferro, reversos metálicos, resíduos da indústria siderúrgica integrada tradicional. Os resíduos de biomassa são provenientes da demolição de casas de madeira, e outros resíduos de biomassa, como limpeza florestal para evitar-se incêndios, resíduos de moinhos, paletes usados e qualquer outra fonte de biomassa. As combinações dos reatores tornaram-se possíveis devido à nova versão do processo de Carbonização Contínua, Carboval, um reator especialmente projetado da tecnologia Lambiotte tradicional, para produzir, de preferência, o carvão vegetal que possui as mesmas características necessárias para alimentar o Mini Alto Forno tradicional a base de carvão.

Oct 30, 2017

By Kwadwo Osseo‑Asare, Isehaq Al‑Nafai

The hydrometallurgical processing of bastnasite is a well-known process that is used to extract rare earth metals. However, more accurate measures are required to enhance the efficiency of extracting and recycling rare earths. In this work, Pourbaix (Eh–pH) diagrams for La-, Nd-, and Pr-(F)-(CO3)-(SO4)-(Cl)-(NO3)-(C2O4)-H2O systems were theoretically derived to investigate the stability relations during the hydrometallurgical processing of bastnasite. The diagrams for RE-H2O systems show similar trends to the original ones drown by Pourbaix. The stability domains of RE carbonates were presented by RE-CO3-H2O systems with pH range of 4.5–11. In contrast, the diagrams for RE fluorides showed a large stability region of insoluble REF3 (pH ~ − 1.7–12). The decomposition behaviors of REFCO3 were studied by constructing Eh–pH diagrams for RE-F-CO3-H2O system. The stability regions of bastnasite species extend from nearly neutral to basic media (pH ~ 6.5–12). The acid treatment (using H2SO4, HCl, and HNO3) of bastnasite was investigated by constructing Eh–pH diagrams for REF- CO3-(SO4)-(Cl)-(NO3)-H2O systems. According to these systems, REFCO3 can be decomposed at pH ~ 6.5 when treated with H2SO4 and at pH ~ 1.7 when treated with HCl and HNO3 acids. On the other hand, the alkaline treatment of REFCO3 converts it to RE(OH)3 at pH ~ 11. The recovery of rare earths ions was studied with the aid of RE-C2O4-H2O systems which shows a wide stability region for RE oxalates in pH range of − 2–11. This theoretical approach explained the aqueous relations in the hydrometallurgical processing of bastnasite ore and it can improve the practical hydrometallurgical processing of such ores.

Feb 9, 2024

Discussion of the paper of O. P. Hood, presented at the Pittsburgh meeting, October, 1914, and printed in Bulletin No. 94, October, 1914, pp. 2607 to 2611. R. V. Norris, Wilkes-Barre, Pa.-I have had a little experience with gasoline locomotives and I want to indorse very strongly Mr. Hood's point with regard to the danger of carbon monoxide poisoning. I think .the terrible danger is not fully realized. I was foolish enough some time ago, in investigating a gasoline locomotive, to attempt to walk out of the mine entry behind it, and for several days I felt very seriously the carbon monoxide effects. The use of gasoline locomotives ought to be confined to mine entries where there is a very large amount of air. One of the grave dangers is their great convenience and the temptation to run them into chambers for just a few moments to get a car or two. GEORGE S. RICE, Pittsburgh, Pa.-Apparently one of the great dangers is in the style of the gasoline engine. When my attention was. first directed to the type of gasoline locomotives which I saw in the foreign mines-France, Belgium, and Germany, I was most favorably impressed with them, and they have given no trouble on account of fumes, so far as I could learn. Large numbers of them were being used, but all were of small capacity, and of a kind in which the speed control is by a governor of the hit-or-miss type, the engine running continuously. Their power capacity was very low, if I remember correctly it was not over 4 or 5 h.p., but they were used under favorable conditions where the grades in the mines were slight, since the entries or tunnels bad a slight grade in favor of-the load, making about the same pull for the empties against the grade as for the load with the grade. I understand the hit-or-miss valve arrangement enables a setting that will give more perfect combustion than can be insured with the valve controlled by the operating man, as in the automobile type of valve and engine used in this country. Apparently the European type of locomotive does not have the capacity to permit use under the conditions existing in this country, where most of our entries or tunnels have variable grades and long heavy trips of mine cars are used.

Jan 4, 1915

Discussion of the paper of O. P. Hood, presented at the Pittsburgh meeting, October, 1914, and printed in Bulletin No. 94, October, 1914, pp. 2607 to 2611. R. V. Norris, Wilkes-Barre, Pa.-I have had a little experience with gasoline locomotives and I want to indorse very strongly Mr. Hood's point with regard to the danger of carbon monoxide poisoning. I think .the terrible danger is not fully realized. I was foolish enough some time ago, in investigating a gasoline locomotive, to attempt to walk out of the mine entry behind it, and for several days I felt very seriously the carbon monoxide effects. The use of gasoline locomotives ought to be confined to mine entries where there is a very large amount of air. One of the grave dangers is their great convenience and the temptation to run them into chambers for just a few moments to get a car or two. GEORGE S. RICE, Pittsburgh, Pa.-Apparently one of the great dangers is in the style of the gasoline engine. When my attention was. first directed to the type of gasoline locomotives which I saw in the foreign mines-France, Belgium, and Germany, I was most favorably impressed with them, and they have given no trouble on account of fumes, so far as I could learn. Large numbers of them were being used, but all were of small capacity, and of a kind in which the speed control is by a governor of the hit-or-miss type, the engine running continuously. Their power capacity was very low, if I remember correctly it was not over 4 or 5 h.p., but they were used under favorable conditions where the grades in the mines were slight, since the entries or tunnels bad a slight grade in favor of-the load, making about the same pull for the empties against the grade as for the load with the grade. I understand the hit-or-miss valve arrangement enables a setting that will give more perfect combustion than can be insured with the valve controlled by the operating man, as in the automobile type of valve and engine used in this country. Apparently the European type of locomotive does not have the capacity to permit use under the conditions existing in this country, where most of our entries or tunnels have variable grades and long heavy trips of mine cars are used.

Jan 4, 1915

By Tiago Ramos Ribeiro

Os processos de redução direta utilizam-se de gases redutores (CO e H2) para redução do ferro e produção do DRI. A geração deste gás se dá através de reforma de metano que pode ser feita em um reformador, ou dentro do reator de redução com o DRI como catalizador. O último caso ocorre nos processos auto reformadores. A cinética da reforma de metano com H2O catalisada por DRI foi estudada em temperaturas entre 875°C e 1050°C. Os resultados mostraram que até conversão de metano de 0,50, a reforma é controlada por reação química catalítica conforme mecanismo proposto por Münster e Grabke(3,4). Acima desta conversão, o mecanismo não foi determinado. O uso de gás com potencial abaixo do limite para carburação (CH4/H2O < 1) resultou em DRI sem carbono. Com gás de potencial igual ou acima do limite, a carburação do DRI ocorreu e no caso do gás similar ao do processo industrial a carburação impediu a reação catalítica de reforma.

Oct 30, 2017

By Klaus-Peter M. Hanke

INTRODUCTION In early 1979 Jim Walter Resources, Inc. (JWR) of Brookwood, Alabama approached TMCI Construction, Inc (TMCI) to make a proposal on a program that involved the sinking of up to 10 ventilation shafts of approximately 6.7 m (22 ft) diameter and ranging in depth from 500 to 700 m (1650 to 2300 ft) for the JWR coal mines in Alabama. At this time TMCI was already constructing the first spiral underground bunker (capacity 2000 tons) in North America for the JWR organization at their No. 4 mine in Alabama. The TMCI proposal was based on the use of the mos modern large diameter shaft boring machine rather than sinking the shafts using the conventional drill blast-muck technique. The proposal was made based o: the experiences by the parent company, Thyssen Schachtbau, which has been using this type of machin in Germany for shaft boring since 1971. As a result of the TMCI proposal JWR issued a purchase order to TMCI for the construction of four 6.7 m (22 ft) diameter, concrete lined, unfurnished ventilation shafts ranging in depth from 500 to 700 (1650 to 2300 ft). An order was thus placed with WIRTH Machinen- and Bohrgeraete Fabrik GmbH, in Germany for the manufacture of a model 650/850 E/Sch "Schachtbohrmaschine" (Vertical Shaft Borer = V-mole which arrived on site in Alabama in early 1981. The first V-mole GSB 450/500 was introduced in Germany in 1971 and was capable of enlarging in one step a pre-drilled 1.2 m (4 ft) pilot hole to 4.5 - 5.0 m (14.7 - 16.4 ft). This machine has sunk 9 staple shafts and deepened one surface shaft for a total of 2360 m (7740 ft) of shafts. On the last shaft boring operation in 1978 the machine was converted as an experiment to drill without a pilot hol using a hydraulic pumping system to remove the cutting debris. A second generation machine, the SB VI 500/650, was introduced in 1977 for enlarging the pilot hole to a range of 5.0 - 6.5 m (16.4 - 21.3 ft) diameter. This machine is still in operation and has already drilled well over 2000 m (6500 ft) of shaft. The third generation of V-mole, the SB VII 650/85( for diameters from 6.5 to 8.5 m (21.3 to 27.9 ft) was: commissioned in May 1980 and has been used for two surface shaft deepenings totalling 606 m (1990 ft) with another scheduled for 1982. The main advantages favouring the use of such V-moles were identified as: 1) A reduction in manpower to the crew required in a conventional shaft sinking operation. 2) A considerable reduction in time to complete a shaft compared to conventional techniques. 3) The use of the V-mole eliminates many of the hazards encountered in conventional sinking. Based on the successful performance of the first three V-moles in Germany, Thyssen Schachtbau decided to employ this principle abroad. In 1980 a second machine of the third generation was built and is now operated by TMCI Construction, Inc. in Alabama. The first shaft was completed at the end of 1981 and this paper describes the method of operation including some unique aspects not attempted on prior V-mole operations and some of the statistics arising out of the experiences during the first shaft boring operation. THE NO. 7 MINE FAN SHAFT SITE Jim Walter Resources, Inc. was formed in 1970 to exploit the coal field in Alabama on the southern tip of the Appalachian coal field. The coal reserves amount to around 650 million tons of mainly good quality coking coal of which about 350 million tons are to be extracted over the next 30 years. Shaft sinking and preparatory work began in 1972, and at present 6 mines are producing around 5.4 million t.p.a. Annual production is to expand to 10 million t.p.a. as soon as possible, and the ventilation shafts to be sunk by TMCI play a vital role towards attaining this goal. The first shaft site is located at the No.7 mine, near Brookwood, Alabama. The actual location of the shaft relative to the production shafts is shown on the mine plan (Fig. 1), which also shows the room-and-pillar extraction system used at present. The mine plan further shows the conveyor route used for the muck removal. The geological survey showed that the strata consisted of horizontal layers of mainly sandstone, sandy shale and shale interspersed with several coal seams. The seam being extracted at the No. 7 mine is a combined seam made up of the Blue Creek and Mary Lee seams at a depth of 513 m (1682 ft) and having an average seam thickness of about 2 m (6 ft). At the beginning of September 1980 the surface site preparation and pre-grouting work was completed by JWR, and TMCI was able to commence with Stage I of the shaft sinking program - the drilling of the pilot hole.

Jan 1, 1982

By Leticia Gabriela Winck

As escórias de aciaria, além de ser um coproduto da fabricação do aço, desempenham um papel importante na qualidade dos aços produzidos. Entender como elas se comportam durante o processo de refino é fundamental. Por exemplo, no refino secundário, a absorção de inclusões pela escória é umas das principais formas de se obter aços com maior limpeza inclusionária, e consequentemente, mais nobres. O presente trabalho tem como objetivo a caracterização de fases de escórias de refino secundário do sistema CMAS (CaO, MgO, Al2O3, SiO2), a fim de se obter informações a respeito de sua composição e fração líquida, além de prováveis fases sólidas. Para isso, quatro amostras de diferentes composições químicas foram fundidas em forno elétrico resistivo a altas temperaturas. As amostras também foram analisadas por diferentes técnicas como: microscopia eletrônica de varredura com sistema EDS acoplado (MEV/EDS), difração de raios X e simulação termodinâmica. Os resultados obtidos experimentalmente foram condizentes com as simulações termodinâmicas e com os resultados encontrados na literatura.

Aug 16, 2017

By G P. Taylor

Mining Lease SML 57 was registered to Mount Kasi on 5 January, 1995. The Mount Kasi gold mine is located in Vanua Levu, Fiji's second largest island and operated from 1932 to 1946 producing 261,000t of ore at an average grade of 7.5g/t Au. The deposit represents a structurally controlled style of high sulphidation copper gold mineralisation with peripheral low sulphidation mesothermal vein type gold mineralisation. The resource consists of 1,048,000 tonnes of residual soils (eluvium) containing 1.9 g/t Au at 0.5 g/t Au cut off and 1,240,000 tonnes of hard rock at 3.0 g/t Au and 1.0 g/t Au cut. 94 drill holes, 298 auger holes and 85 pits were modelled to outline the resource. 29% of the pits bottomed in mineralisation and it is likely the full thickness of eluvium has been understated. The pit is scheduled to produce 500,000 tonnes of ore per annum to yield 35,000 ounces of gold with an initial 2 years of eluvial ore followed by a further 2 years of hard rock ore. Total capital costs are estimated to be less than 10.0 million dollars with construction planned to commence in 1995. The likelihood of locating further ore is high.

Jan 1, 1995

By Finn Ouchterlony

A simple bilinear R-curve description of crack extension resistance is applied to the testing of sub-size rock core specimens. The K-curve consists of a linear sub-critical part and a flat post-critical part. Formulas for the apparent energy rate resistance quantities Gm, Jm, and [R] are developed. Experiments on notched cores of Ekeberg marble, Bohus granite, and Stripa granite are compared with these predictions. The R-curve model gives reasonable results for Gm -data but fails essentially to describe the Jm and [R]-data. Another model with a sharply increasing linear post-critical part could possibly account for the [R]-data, but direct R-curve measurements seem a better approach.

Jan 1, 1982

By Milton E. Wadsworth, R. Ted Wimber

Cobalt sulfate solutions containing ammonium acetate and chloroplatinic acid were reduced by hydrogen in a pyrex-glass lined autoclave in the temperature range of 170o to 232°C and hydrogen partial pressure range of 115 to 830 psia. The reduction rate was directly proportional to the hydrogen partial pressure and surface area of the pyrex glass and was independent of the quantity of chloroplatinic acid added initially. Experiments involving the variation of the relative concentration of ammonium acetate indicated that the reducible cobalt complex was probably the diacetate complex of cobalt, Co(AC)4H20, or a new mononcetate complex Co Ac, which was in solubility equilibrium with a pink precipitate of CO(AC)-4HzO. THE reaction in which a metal is dissolved by an acid to produce gaseous hydrogen and a salt solution was discovered early in the history of chemistry. In 1859 Beketoff found experimentally that this reaction could be reversed; i.e., a salt solution could be reduced by gaseous hydrogen to produce a metal and an acid. A review of work done on this phenomenon since that time may be found elsewhere., The hydrogen reduction of a cobalt salt solution is facilitated by complexing the cobalt ion. An ammonia complex of cobalt has been reduced commercially in the recovery of cobalt metal. A new reducible complex of cobalt was discovered5 when it was found that a co-baltous sulfate solution containing ammonium acetate could be reduced by hydrogen at temperatures in the region of 200°C. When a cobalt sulfate-ammonium acetate solution was heated to a temperature below its normal boiling point, a violet color became apparent, indicating complex formation. The nature of this complex was investigated5 by the addition of NH4Ac to a CoSO4 solution maintained at 85o. During the first additions of NH, Ac, the pH of the solution remained fairly constant at about 5.85. However, as the ratio of NH,Ac to CoSO, approached two, the pH rose and then leveled off at about 6.05. The absorption spectra of a Co(Ac), solution and a CoSO,, NH Ac solution were obtained at 85°C and were compared and found to be the same. These findings suggested that the diacetate complex of cobalt, Co(Ac),.4H20, was formed at 85°C. When a cobalt sulfate-ammonium acetate solution was heated to a temperature above about 165o, a finely divided pink precipitate appeared. The X-ray diffraction pattern of this precipitate indicated that it was Co(Ac), - 4H,O. In addition, it was discovered that when chloroplatinic acid, H,PtCl;, was added initially to the cobalt sulfate-ammonium acetate solution, a faster reduction was obtained. The roles of the solution complex, pink precipitate and chloroplatinic acid in the reduction process were then investigated. APPARATUS The experimental work was carried out in a two-liter stainless-steel autoclave. Adetailed description of the autoclave and the auxiliary equipment used in maintaining constant temperature and pressure may be found elsewhere.= Because the stainless steel was corroded, and also because it acted as a hydrogena-tion catalyst, an all-glass liner was fabricated such that the solution came only into contact with flame-polished pyrex glass. EXPERIMENTAL PROCEDURE The solutions used in the experimental work were prepared by dissolving reagent grade chemicals in distilled water. Although variation of the brand of ammonium acetate appeared to have no effect on the experimental results, CoSO, 7H O from the J. T. Baker Chemical Co. of Phillipsburg, N. J.,was found to give faster reductions than that prepared by Allied Chemical and Dye Corp., N. Y. The former was used throughout the course of the experimental work and was weighed up at the outset of each experiment. The ammonium acetate was dissolved to form a 6M stock solution, which was stored under refrigeration. A 10 pct solution of chloroplatinic acid (J. T. Baker Chemical Co.) was diluted to a 1.15 x 1Q2 M stock solution, which was standardized by precipitation of K,PtCl, as outlined by Scott. The appropriate volume of the chloroplatinic acid, H,PtCl,, solution was pipetted into the clean, dry glass liner. The cobalt sulfate-ammonium acetate solution, which had previously been saturated with

Jan 1, 1962

By N. A. Gokcen, J. Chipman

Aluminum and oxygen dissolved in liquid iron were brought into equilibrium with pure alumina crucibles and atmospheres of known H2O and H2 contents to study the reactions: 1—Al2O3(s) = 2 Al + 3 0; 2—Al2o3(s) + 3H2(g) = 2Al+ 3H2o(g); and 3—H2(9) +O = H2O(g). Aluminum strongly reduces the activity coefficient of oxygen and similarly oxygen reduces that of aluminum. Values of the product [% All" • [% O]3 are much smaller than those found in previous experimental studies and are of the order of magnitude of the calculated values. ALUMINUM is the strongest deoxidizer commonly A used in steelmaking, but the extent to which it removes dissolved oxygen has been debatable. The relationship between aluminum and oxygen has not been determined reliably not only on account of the usual experimental difficulties at high temperatures but also because of uncertainties in the analyses of very small concentrations of oxygen and aluminum. The earliest experimental attempt of Herty and coworkers' was followed by a more systematic study of Wentrup and Hieber.' These authors added aluminum to liquid iron of high oxygen content in an induction furnace and considered that 10 min was sufficient to remove the deoxidation products from the melt. Parts of the melts thus obtained were poured into a copper mold and analyzed for total aluminum and oxygen (soluble plus insoluble forms), assuming that the insoluble parts were in solution at the temperatures from which samples were taken. It is conceivable that the furnace atmosphere in their experiments, consisting of mainly air at 20 mm Hg pressure, was a serious source of continuous oxidation and therefore that their oxygen concentrations were correspondingly high. Scattering of their data was explained to be well within the maximum inaccuracy of 10°C in the temperature measurements and errors of ±0.002 pct each in the oxygen and total aluminum analyses. Maximum and minimum deoxidation values, i.e., values of the product [% All' . [% O] differed by factors of 10 to 15; mean values of 9x10-11 and 7.5x10-9 ere reported at 1600" and 1700°C, respectively. Hilty and Craftsv determined the solubility of oxygen in liquid iron containing aluminum, using a rotating induction furnace. Pure alumina crucibles used in their experiments contained the liquid iron which in turn acted as a container for slags of varying compositions consisting mainly of Al2O3, Fe2O3, and FeO. The furnace was continuously flushed with argon, and additions of aluminum and Fe2O3 were made in the course of each experimental heat. The inner surfaces of their alumina crucibles were covered with a substance other than pure Al2O3, containing both iron oxide and alumina. Although frequent slag additions can change the composition of slag in the liquid iron cup formed by rotation, the inner surface of the crucible must depend upon the transfer of oxygen or aluminum through the liquid iron for any adjustment in composition. It is not clear that their metal was in equilibrium with the crucible wall, but it is clear that it was not in equilibrium with Al2O3. Their deoxidation product, [% A].]" • [% O]3, varied by a factor of more than 50; the average values of 2.8x10- and 1.0x10-7 were selected for temperatures of 1600" and 1700°C, respectively. Aside from the experimental determinations, attempts have been made to calculate the deoxidation constant for aluminum indirectly from thermody-namic data. Schenck4 combined the thermodynamic data for Al2O3 and dissolved oxygen in liquid iron by assuming an ideal solution. His calculated values are 2.0x10-15 and 3.2x10-13 at 1600" and 1700°C, respectively. Later, Chipman5 attempted to correct for the deviation from ideality and derived an expression which led to deoxidation values of 2.0x10-14 and 1.1x10-12 at 1600" and 1700°C, respectively. The errors in these treatments originate mainly from inaccuracies of thermal data and uncertainties regarding the activity coefficients of dissolved oxygen and aluminum. The purpose of this investigation was to study the equilibria represented in the following reactions in the presence of pure alumina: Al2O3(s) = 2Al + 3O K = aAl2.ao3 [1] Al2O3(s) + 3H2(g) = 2Al + 3H2O(g) H2O K2 = aAl2(H2O/H2 ) [2] H2(g) +O = H2O(g) K3 = 1/ao (H2) [3] The experimental method consisted of melting pure electrolytic iron, usually with an initial charge of aluminum, in pure dense alumina crucibles under a controlled atmosphere of H,O and H2 and holding

Jan 1, 1954

By A. K. Mukherjee, J. E. Dorn, J. D. Mole

Investigations were carried out on the effect of polyslip on the strain hardening of aluminum single crystals. The orientations investigated were those lor which the tensile axis was in the [001], [111], [112], and [012] directions plus another for which the Schmid angles for {111}(110) slip were 1 deg. The experimental data were analyzed on a model based on the intersection of dislocations with particular emphasis on the effect of polyslip on the activation volume for inter-section. It is shown that the rate of strain hardening inreases for those orientations wherein attractive dislocation intersections occur and that those orientations which produce the greater number of such intersections exhibit the greater strain hardening. Good correlation of the data is obtained with the concept that attractive junctions, as proposed by Saada, Play an important role in accounting for the rate of strain hardening. EXISTING concepts on the nature and cause of strain hardening in fcc metals have been deduced principally from experiments on the deformation of single crystals under single slip. The effect of crystal orientation on the shapes of the stress-strain curves for single slip have been summarized by seegerl and more recently by Clarebrough and Hargreaves.2 Tensile specimens whose axes fall near the center of the [001]-[011] line of the standard triangle of the stereographic projection exhibit the longest range of easy glide (Stage I) and the lowest rates of linear hardening (Stage 11) whereas specimens whose axes lie near fie [001]-[111] line of the standard triangle have limited or no easy-glide range and exhibit somewhat higher linear strain-hardening rates. Specimens whose axes lie near the [001] or the [ill] poles do not exhibit easy glide and have the highest rates of linear hardening. Kocks3 has shown that the highest rates of linear hardening Occur under Polyslip when the tensile axis coincides with the [111] or the [ 001] pole. Since the rate of strain hardening is sensitive to specimen orientation and the incidence of polyslip, these relationships might help to discriminate between various dislocation models for strain hardening in fcc metals. Previous attempts to analyze the effect of orientation on strain hardening,1"3 however, did not provide a unique answer to this problem. Consequently the present investigation was undertaken wherein additional data, particularly that for the effect of polyslip on the activation volume for intersection, was also determined in order to provide more complete information on the details of strain hardening. Whereas analyses of these data reveal that several recommended models for strain hardening are at variance with the facts, good correlation of the data is obtained with the concept that attractive junctions4 play an important role in accounting for the rate of strain hardening. I) EXPERIMENTAL APPROACH seegerl demonstrated that slip in fcc crystals at low temperatures is dependent on thermally activated intersection of glide dislocations with forest dislocations. This has been confirmed by tests on single crystals of aluminum by Mitra, Osborne and Dorn5 and on polycrystalline aluminum by Mitra and Darn.' Thus in accord with Seeger's theory, the shear strain rate, ?, below a critical temperature, T, is where .V is the number of points of contact per unit volume between forest dislocations and glide dislocations, A is the area swept out per successful intersection, b is the Burgers vector, v is the frequency of vibration of the segment of the glide dislocation undertaking intersection, U is the activation energy for intersection, k is Boltzmann's constant, and T is the absolute temperature. For aluminum, which has an extremely high staeking-fault energy, the constriction energy is negligibly small and therefore the activation energy decreases practically linearly with the stress according to as will be recomfirmed later, where Uo is jog energy at the absolute zero, G and Go are the shear moduli at the test temperature T and O°K, respectively, L is the spacing of the forest dislocations, t is the applied shear stress for slip, and tGo is the stress field that must be surmounted athermally.

Jan 1, 1965

By E. T. Turkdogan, L. J. Martonik, R. J. Fruehan

Electrochemical measuretnents of the solid oxide electrolyte galvanic cells CY-Cr2O3 I ZrO2 (CaO) 1 O (in Fe alloy) CY-Cr2O3 I Tho2 (Y2O3)I O en Fe alloy) have been made at 1600°C (2912°F) in order to test the Performance of such cells at liquid steel temperatures. The oxygen pvobe (cell) consists of a disk of ZrO2 (CaO) or Tho2 (Y2O3) electrolyte fused at one end of a silica tube filled with a mixture of Cr-Cr2O3 which is the reference electrode. Upon immersion in liquid steel, the electromotive force readings achieve a steady value within a few seconds, and remain steady for 30 win or more. The perforwzance of the probes has been tested using Fe-O, Fe-Si-O, Fe-Cr-O, Fe-V-O, and Fe-Al-O alloys; the oxygen contents of liquid steel derived from the measured electromotive forces are in satisfactory agreement with those determined by arulysis. Use of the probe in the deoxi-datiorz of steel, in laboratory experiments, is discussed. The results indicate that there is insignificant electronic conductivity in ZrO2(CuO) at oxygen activities down to those corresponding to 10 ppm in steel. At lower oxygen activities, probes tipped with ThOn (Y2O3) disks perform satisfactorily at oxygen activities down to 1 ppm O or less. THE key to the control of deoxidation of steel is a sensing device to measure rapidly the concentration of oxygen in liquid steel in the furnace, ladle or tun-dish at any desired stage of deoxidation. The analysis of the cast steel by the neutron-activation or vacuum-fusion method gives total oxygen as oxide and silicate inclusions. This analysis is important for guidance to steel cleanliness; however, such a postmortem is of little value in the control of deoxidation of liquid steel. At the General Meeting of the American Iron and Steel Institute in New York, 1968, Turkdogan and Fruehan' presented a paper on the preliminary results of the work done in this laboratory on rapid determination of oxygen in steel by an oxygen probe. Details of the work done in this laboratory leading to the development of a galvanic cell for the determination of oxygen in liquid steel, and the results of the tests made are given in this paper. It was through Wagner's contributions, since the early Thirties, to the physical chemistry of semiconductors in general that it ultimately became possible to construct galvanic cells for application at high temperatures. In 1957, Kiukkola and wagner2 successfully demonstrated the use of several solid electrolytes in measuring the free energies of several chemical reactions, in particular, the use of lime-stabilized zir-conia in high-temperature oxidation reactions. Starting 7 years later, a number of papers appeared in the technical literature3-' demonstrating possible applicability of galvanic cells for the determination of oxygen in liquid steel. In the earliest work, Japanese investigators3j4 experimented with various types of reference electrodes, e.g., graphite-saturated liquid iron at 1 atm CO or Ni-NiO mixtures; the results obtained, though promising, were not of sufficient accuracy. Except for the work of Baker and West,6 all other investigators5,7,8 showed that ZrO2(CaO) electrolyte could be used for this purpose. The main part of the galvanic cell used by Fischer and ~ckermann' and by schwerdtfeger7 (the latter work was done in this laboratory), consisted of a ZrO2(CaO) tube, -1 cm ID, closed at one end, with a platinum contact wire fixed mechanically inside the closed end. The tube was flushed with a gas of known oxygen partial pressure, e.g., air, CO-CO2 or H2-CO2 mixtures; gas along with the platinum lead wire served as the reference electrode. The oxygen contents derived from measured electromotive forces agreed reasonably well with the oxygen contents determined by vacuum-fusion analysis. It is evident from recent investigations that the electromotive force technique using a solid oxide electrolyte is fundamentally well suited for the determination of oxygen in liquid steel. However, it is equally clear that the cell arrangement of the type as commonly used is in need of considerable improvement, as it exhibits several shortcomings for industrial and even laboratory use. 1) Because of its size, the zirconia tube, though stabilized, has a poor resistance to thermal shock. 2) Fine pores and microcracks, which are invariably present in zirconia tubes, are detrimental to the satisfactory operation of the cell, particularly when gas reference electrodes are used. 3) Air or carbon dioxide reference electrodes give rise to high electromotive force readings; as a result, the determination of oxygen in steel becomes less accurate. For higher accuracy, the oxygen partial pressure of the reference electrode should be in the range similar to that of oxygen in steel. 4) Even in laboratory experiments, difficulties are experienced when flushing the tube with gases and maintaining the proper gas flow rate. Fischer and Ackermann,' who used air as the reference electrode, reported that when the flow rate was too low, furnace gases would leak into the electrolyte tube, therefore lowering the oxygen potential and measured electromotive force. The required flow rate in order to avoid leakage depended on the tightness of the electrolyte tube which varied with different tubes, thus making it difficult to predict in advance the required flow rate. However, if the flow rate is too high the inside wall of the electrolyte tube would be cooler than the wall

Jan 1, 1970

By Milca Ventura dos Santos, Ricardo Rodrigues Grizotti, Luciano Henrique Andrade de Resende, Francisco Ricardo Casa Neto, Paulo Roberto de Oliveira Junior, Bruno Rodrigues Ferreira

O trabalho tem por objetivo demonstrar o processo de desenvolvimento e implantação da automatização nas operações, atividades de almoxarifados (recebimento, armazenagem, movimentação, inventário, picking e entrega de materiais), com o uso da tecnologia SAP FIORI com interface nos sistemas operacionais Android e IOS para utilização do Mobile (smartphones e tablet’s), já alinhado ao momento da indústria 4.0, visando inovações tecnológicas nos campos de automação, controle e tecnologia da informação. O desenvolvimento nesta nova plataforma visa tornar as operações de almoxarifados mais ágeis e eficientes, buscando otimizar o processamento das informações com mais rapidez, redução do tempo de permanência das mercadorias nas áreas de transferência e gerar maior rastreabilidade dos processamentos com interface direta e on-line com o ERP-SAP da organização. A metodologia do trabalho foi identificar as oportunidades de explorar as melhores potencialidades das soluções do SAP Fiori, alinhadas aos sistemas operacionais Android e IOS para uso de celulares, tablet’s, com comunicação através da rede interna e/ou 3G/4G sempre visando otimizar todas as atividades operacionais (fluxo de materiais) e administrativas (fluxo de informações) dentro dos processos dos almoxarifados e suas áreas de interface. O projeto iniciou-se e sendo implementado nas unidades de Planos (ArcelorMittal Tubarão e Vega), e com plano de expansão para as unidades de Longos da ArcelorMital Brasil durante o ano de 2019. Nesta primeira etapa o resultado alcançado foi de plena adequação, tendo sido encontrado benefícios em redução de erros; aumento de segurança; redução de custos; otimização de processos; transparência em dados; customização de produtos, o qual espera-se que a curva de aprendizado naturalmente nos levará a adoção de novas soluções incrementais resultando nos melhores níveis de gestão do processo de armazenagem e movimentação de materiais.

Oct 1, 2019

By Weston Bourret

The need for wartime supplies of uranium for the Manhattan Project prompted a 1944 study of uranium in South Africa. Uraninite had been reported by R.A. Cooper in 1923 in a Witwatersrand heavy- mineral concentrate, and the search for uranium, therefore, included the district's 30 operating mills. The method of investigation was simple: take bulk concentrate samples from the Wifley tables and determine their mineralogy. Samples were taken on a daily basis, although weekly composites also were taken of some mills. In 1944, most mills had simple gravity circuits and produced (I) a gravity concentrate, and (2) an all-slime [-75 pm (-200 mesh)] product. The tonnage throughput was known, and from that, head assays could be calculated. Concentrate samples were sent to the United States for chemical analyses. A Geiger counter set up in a Johannesburg hotel room provided preliminary data. The early data showed uraninite to be widespread. Microscopic, mineragraphic, and siezing tests were all under- taken in Johannesburg. Ultimately, tests led to a high grade (+90%) uraninite concentrate. Platinum and other heavies were the impurities. In seven months, the investigations had reached the stage where it was possible to forecast an annual production of 5.4 to 7.3 kt (6,000 to 8,000 st) of U3O8. The estimate is still realistic. Additional details are found in Bourret (1981).

Jan 1, 1991

By Haysler Apolinário Amoroso Lima, Francisco Pereira Netto, Vladnilson Peter de Souza Ramos, Bruno Nery Stoco, Gilvan Nascimento de Souza

Em um mercado dominado por tijolos de Al2O3-MgO-C, o revestimento de trabalho de panela de aço monolítico e CarbonFree se apresenta como uma tecnologia disruptiva para um novo patamar de qualidade do aço e eficiência energética. O presente estudo relata a motivação para a implementação do primeiro fundo de panela de aço com revestimento monolítico concretado in situ no Brasil, e apresenta uma análise preliminar dos resultados e vantagens observadas. Uma panela da Ternium Brasil foi revestida com refratários de Al2O3-MgO, e colocada em operação sem nenhuma necessidade de ajuste na operação da aciaria. A partir dos dados de processo e das medições a laser, calculou-se o desgaste do revestimento, bem como verificou-se a garantia de qualidade nos aços IF (interstitial free) e a maior preservação na temperatura do aço durante o refino secundário.

Oct 1, 2019

By Dan Plazak

Discussion by Dan Plazak The authors are to be congratulated for presenting a simple and practical tool for quick estimates of ground water flow rates. At the risk of detracting from the simplicity of the method, I would like to suggest a slight refinement to the equation as presented. As the authors noted, the Jacob-Lohman equation (1952) assumes confined-aquifer conditions. To use confined-aquifer equations in water-table aquifers, Jacob (1963) presented a correction to convert water-table aquifer drawdowns [Ahw] to equivalent confined aquifer drawdowns [Ah,: 2] [Ah Ah = Ah - w(1) Cw 2H where: Ah, = Drawdown in confined aquifer: Ahw = Drawdown in water-table aquifer and H = Original saturated thickness of aquifer] Substituting the above in equation ( I) of Hanna. Azrag and Atkinson [4nT Ah - 2H ) Qj2.25 T t(2) 1 nr2 S W] Since the above expression predicts lower pump rates, it causes the Jacob-Lohman equation to agree more closely with appropriate analytical and numerical models. Figure 1, adapted from Fig. 5 of Hanna. Azrag and Atkinson, illustrates the closer agreement of the modified equation to their numerical model, as reflected in Qm/QJL ratios closer to unity. The agreement improves particularly as drawdown [Ah] becomes large in relation to aquifer thickness H. An additional advantage of the modified equation is that Hanna, Azrag and Atkinson's correction factor C is much more stable as pit depth increases. Assuming, as did Hanna, Azrag and Atkinson, that their numerical model is an accurate predictor, it is clear that the modification incorporated in equation (2) improves the accuracy of preliminary estimates of ground water flow to a pit.[ ] References Jacob, C.E and Lohman. S. W.. 1952, "Nonsteady flow to a well of constant drawdown in an extensive aquifer." Transactions, American Geophysical Union. Vol, 33, No. 4. pp. 559-569. Jacob. C. E.. 1963, `Determining the permeability of water-table aquifers,' USGS Water-Supply Paper 1536-1, pp. 245-271

Jan 1, 1995

By Yuanbo Zhang, Bin Xu, Guanghui Li, Xiao Kang, Chen Liu, Tao Jiang

Iron-bearing dusts, containing valuable constituents such as Fe, CaO, MgO, C, etc., are generally utilized as raw material in iron ore sintering. However, the dusts characterized by low granulating and refractory performances always lead to negative effects on sintering indexes. As we know, the innovative process named composite agglomeration process (CAP) has a series of advantages compared to traditional sintering process (TSP). In CAP, part or all of the iron-bearing dusts is made into green pellets with 5-15mm in diameter, while the rest of iron-bearing dusts and all of the other fine ores is granulated after mixing with fuels, fluxes and return fines. Compared with TSP, CAP could increase the ratio of iron-bearing dusts from 5% to over 20%. Meanwhile, the yield, ISO tumbler index and productivity reached 75.82%, 65.13% and 1.531t·m-2·h -1, respectively.

Jan 1, 2015

By Max Hebgen

I. Natural Features of State Affecting Power Development .. 792 II. Early Developments. 1. Big Hole Plant................. 792 2. Canyon Feny Plant............... 793 3. Madison Plant No. 1............... 593 4. Black Eagle Plant................ 795 III. Later Developments. 1. Madison River System .............. 795 2. Missouri River System.............. 797 3. Great Falls System............... 797 4. Missoula River Development............ 797 5. Big Fork Development.............. 802 $ IV. Present Capacity of Power Developments....... 802 V. Transmission System...............: . 802 VI. Character of Load. 1. Lighting and Small Power Uses........... 804 2. Street Railways ................ 804 3. Mining................... 804 4. Railroads.................... 808 5. Irrigation................... 810 VII. Operation of System................. 812 VIII. Increase in Use of Power............... 811 IX. New Power Developments............... 814 X. Undeveloped Powers................. 815 It is estimated that the total stationary power now used in the United States. steam. water and gas. is probably over 30.000.000 h. p. The total developed water power is about 6.000.000 h. p. The water power in the United States now economically capable of development probably exceeds 25.000.000 h. p. The total developed and undeveloped power is

Jan 1, 1914

By G. Coetzer

"Prior to operating a non-recovery coke pilot plant, it was critical to ascertain coal cake stability during the loading of a 1 m3 coal cake into the oven. Various compaction parameters were verified and established on a small laboratory-scale compaction machine to obtain a coal cake of acceptable stability. These parameters include cake density, cake surface moisture, transverse strength (force applied perpendicular to the original compacted coal cake layers), and applied force to the coal cake. This work determined the behavioural characteristics of the coal while being compacted either with a full-sized or a 1/3-sized compaction plate in a 9 kg capacity mould. Two different coals were evaluated, namely Waterberg semi-soft coking coal (sscc) and Oaky North hard coking coal.The target wet cake density of 1 100 kg/m3 (79% of 1 400 kg/m3 relative density) was achieved for Waterberg sscc, with a particle size d50 varying between 0.6 mm and 1 mm, utilizing the 1/3-sized compaction plate in the laboratory-scale set-up, with 11.6% surface moisture and 92.2 t/m2 commercial equivalent applied force. For Oaky North hard coking coal, a wet cake density of 1 189 kg/m3 (85% of 1 400 kg/m3 relative density) was achieved at a surface moisture content of 12.3% and at a lower applied force than that for Waterberg sscc, i.e. 78.5 t/m2.Coal cakes of acceptable strength, and therefore sufficient stability for further processing, were obtained for all materials evaluated during this study.Further studies should be conducted to determine the effect of zeta potential during the compaction of coals.IntroductionExxaro Resources has successfully installed and commissioned a world-class stamp-charging horizontal 1 t electrically-heated pilot-scale coke oven at its Metallurgy Services facility. Prior to operating the coke non-recovery pilot plant, it is essential to ascertain coal cake stability during the loading of a 1 m3 coal cake into the oven. The design of Exxaro’s pilot plant is such that the coal cake is pushed inside the oven by means of a pusher plate, rather than through a ‘spoon’ feed mechanism, such as is found in industrial horizontal coke ovens. The pusher plate loading mechanism dictates that the coal cake should possess high stability and inherent strength during loading into the oven, owing to frictional forces exerted by the oven floor. In order to obtain a coal cake of acceptable stability, various compaction parameters needed to be verified and established on a small laboratory-scale compaction machine."

Apr 1, 2019