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En quoi consistent les études de suivi des effets sur l?environnement (ESEE)? Les ESEE constituent une méthode de suivi scientifique que l?on peut employer pour déterminer la santé des écosystèmes aquatiques (qui peuvent être touchés par l?activité humaine) et l?efficacité des mesures de protection de l?environnement. Les ESEE sont des évaluations scientifiques itératives du poisson, de l?habitat du poisson et des ressources halieutiques. Le programme comporte des phases séquentielles de deux à six ans de suivi, d?interprétation et de compte rendu au cours desquelles la fréquence et le type de suivi dépendent des résultats des études précédentes. Le programme des ESEE pour les mines de métaux est fondé sur un accord conclu à l?unanimité entre les intervenants. Les exigences du programme et les guides techniques connexes ont été élaborés à la suite d?une consultation multilatérale à laquelle ont participé les représentants du secteur privé, du gouvernement et des collectivités. Toutes les mines assujetties au Règlement sur les effluents des mines de métaux (REMM), aux termes de la Loi sur les pê ches, doivent procéder à une ESEE dans le cadre de l?autorisation qu?ils ont reç ue de rejeter des effluents. Le REMM a été enregistré le 6 juin 2002 et publié dans la Partie II de la Gazette du Canada le 19 juin 2002 (SOR/DORS/2002-222).

Nov 1, 2002

By Juan Ruiz-Ornelas, Yousef Mohassab, Ricardo Morales-Estrella, Hong Yong Sohn, Noemi Ortiz-Lara

The effect of mechanical activation on the reduction kinetics of magnetite concentrate by hydrogen was studied. The magnetite concentrate was milled for 8 h using a planetary mill. After the milling process, the average particle size was reduced from 14 to 4.4 m resulting in a lattice microstrain of 0.30. Thermogravimetric experiments were conducted to focus on the chemical reaction as the rate controlling factor by eliminating external mass transfer effects and using a thin layer of particles to remove interstitial diffusion resistance. The onset temperature of reduction was decreased due to the mechanical activation, and the degree of conversion was decreased by sintering of particles which was confirmed by SEM analyses. In view of the results, a reaction rate expression is discussed from which the activation energy is calculated.

Jan 1, 2016

Aluminum Production. -By October 1, Aluminum Company of America will restart a 35,000-ton-per-year unit at its aluminum smelter at Rockdale, Tex., restoring that facility to its full capacity of 325,000 tons annually. Primary Ingot Price Increase. -Most U.S. aluminum producers in mid-September were quoting a price of 72 cents per pound for primary aluminum ingot. On September 19, Kaiser Aluminum & Chemical Corp. announced that it would increase the price of primary aluminum ingot 4 cents to 76 cents per pound.

Jan 1, 1980

By B. DE MARE

THE No. 6 open-hearth furnace at the plant of the Worth Steel Co., Claymont, Del., is the first to be rebuilt according to the Kuehn system. This as well as the other five furnaces at Claymont, has a nominal capacity of 75 tons, but the actual charge is about 242,000 lb. No hot metal being available, the pig-iron is charged cold. Oil of low grade with an asphalt base is used as fuel. These two items have to be kept in mind when discussing the actual fuel consumption. Careful records have been kept covering a five weeks run and the following is a brief summary of them The time required to heat the furnace preparatory to charging from the time a wood fire was started until charging commenced was 36 hours. This, I understand, is much less than with furnaces of standard design. The draft of the furnace, as shown by a gage in the stack-flue, is 1.25 in. The maximum draft with new checkers on former runs was 1.50 in., this draft gradu¬ally decreasing as the checkers closed up. Both of the first helpers claim the present draft is all they need for the proper working of the furnace, and, as with the Kuehn regenerators the draft remains practically the same from beginning to end of a run, this is satisfactory.

Jan 1, 1929

By S. S. Peng

Successful longwall mining requires a good roof control. A good roof control implies that: (1) no excessive pressure is build up in the face powered supports, and (2) chain pillars are designed in such a way that panel entries are well protected and interactions between adjacent panels are minimized. A clear understanding of strata behavior around longwall panels due to face movement is, therefore, the foremost requirement for achieving better roof control. This dissertation is designed to analyze the effects of strata behavior on longwall panels due to the mining activities. The following topics are studied: (1) the weighting, phenomena and their effects on front abutments, and (2) the chain pillar stability and pillar design under various roof conditions. Three dimensional finite element analysis was employed. The effect of parameters such as overburden depth, mechanical properties of the immediate roof and main roof, panel width, and size of chain pillar on (t) and (2) were analyzed. Four typical models were utilized to simulate various phases of panel extraction under various combinations of the above parameters; model one is to simulate the beginning of panel mining; model two is to simulate the situation that longwall face has passed more than half of panel length; model three is to simulate the completion of panel production; and model four is to simulate the second panel mining. The following formulae have been developed by applying multiple regression model to analyze the finite clement results: (1) a formula that classifies the type of root strata at the face area. (2) formulae that predict the first weighting and periodic weighting lengths. (3) a formula for design of the chain pillar size. Case studies were performed to check the validity of the formulae proposed. Comparison of the formulae proposed for the chain pillar design with other formulae were also performed.

Jan 1, 1984

By William J. Harris, Morris Cohen

INTRODUCTION THE recent application of lineal analysis1,2 to the austenite-martensite reaction has made possible a quantitative study of the kinetics of this transformation during rapid cooling. Martensite range curves can thus be constructed to portray the onset of the reaction at [M.] and its subsequent progress as a function of temperature down to and below the ambient. It now seems in order to investigate other aspects of the martensite transformation, using this quantitative method of approach. One of the least understood characteristics of the austenite-martensite reaction is that of stabilization which has been defined by Troiano and Greninger3 as "a lowering of [M.], resulting from aging, without change in chemical composition of the parent solid solution." In other words, if the hardening quench is arrested at a predetermined subcritical temperature (Th) for a sufficient period of time, more austenite may be retained at a given lower or reference temperature (Tr) than if the steel had been cooled directly and rapidly to Tr in the first place. For the purposes of the work at hand, the extent of stabilization produced by the isothermal treatment at Th, is measured explicitly in terms of the excess austenite [(S)] that exists in the steel at Tr, over and above the amount that is normally present after direct quenching to Tr. Tr is conveniently taken to be room temperature, but this choice is not essential and is sometimes undesirable. The holding temperature (Th) may be above or below [M], and still cause stabilization depending upon the chemistry of the austenite. Stabilization has been found to occur in the presence of bainite4 and of martensite5,6,7,8 as well as in the absence of either.9 The phenomenon of stabilization is not concerned with (and may even be obscured by) ferrite formation or any other type of phase change occurring at Th that alters the chemistry of the remaining austenite. Such a structural change would obviously influence the martensite transformation during subsequent cooling. Stabilization, however, is more subtle; it appears to manifest itself without detectable variation of the austenite composition, whether in the presence or absence of transformation products. There are relatively few direct references to stabilization in the literature. The stabilizing effect of room temperature aging and tempering on the subzero transformation of retained austenite has been clearly shown in plain carbon,6.8 low alloy 6.7.8 and high alloy tool steels.10,5 Starting with the as-hardened steel, the degree of stabilization increases with tempering time and temperature through

Jan 1, 1948

By J. F. Olk, E. D. Spaulding, R. E. Thurmond, G. A. Komadina, R. W. Hernlund, J. A. Journeay

THE Pima pit is a 1700x1400-St oval, the long T axis parallel to the strike of the orebody. The north side of the pit is carried as a final pit slope that coincides with the footwall of the orebody. The south side and east and west ends of the pit are working slopes continually being stripped back toward the final slopes. An inclined roadway extending from the natural ground surface on a 5 pct grade down to the north- east corner provides access to the pit. This road enters the pit 130 ft below the natural surface and continues as a pit ramp on a 5 pct grade to the 3150-ft bench (roughly the base of the alluvial cover). At this point the ramp system is steepened to a 12 pct grade and continues to the pit bottom. The 5 pct grade is maintained in the alluvial section to facilitate scraper haulage out of the pit. In addition to this main access ramp, temporary working ramps in the alluvial areas allow shorter routes to dumps. These are left on top of working benches and do not change the overall working slopes. Below the base of the alluvium, haulage is by truck down to the skip loading point or up from the bottom to the skip loading point.

Jan 4, 1958

By Samuel Filgueiras Rodrigues, Sebastião Raimundo de Jesus Belém leitão Filho, Gedeon Silva Reis, Eden Santos Silva

Nesse trabalho estudou-se o retardo na cinética de amaciamento estático do aço inoxidável austenitico ASTM F-1586 (ISO 5832-9) usado na confecção de implantes ortopédicos, por meio de ensaios de torção a quente isotérmico em duplo passe. Inicialmente as amostras foram aquecidas por indução até a temperatura de 1250 oC e mantidas por 300 s para solubilização, em seguida resfriadas até a temperatura de deformação (Tdef), que variou de 1000 a 1200 oC, com passes de deformações de ε1 = ε2 = 0,30, taxa de deformação de 1,0 s-1 e tempo entre passes (tp) variando entre 0,1 – 1800 s, simulando um processo de forjamento a quente industrial de um dispositivo ortopédico. Os resultados da simulação física do processamento termomecânico indicaram que 60 % do amaciamento dá-se por recuperação estática (SRV), com moderado valor de energia de falha de empilhamento (γEFE ~ 69 mJ/m2) do aço e tempo de encubação pra iniciar a recristalização estática (SRX) maior que 10 s abaixo de 1100 oC com formação de patamares nas curvas de amaciamento Xs vs tp, indicando atraso na cinética de recristalização estática (SRX) resultante do efeito dos precipitados da fase Z (NbCrN) induzidos por deformação nos contornos dos grãos austeniticos.

Nov 18, 2019

By Aziz NI

There are a number of methods available for the determination of the fracture toughness of rock. Some of the most recognised methods include the hollow pressured cylinder, the short-rod, the chevron - edge-notched round bar in bending and the disc-shaped compact specimen. Most of these tests are difficult and expensive to conduct. In this paper the simple Brazilian testing of discs for tensile strength has been used to determine their fracture toughness. Tests were conducted on six different rock types and the values of the fracture toughness obtained for each type are in close agreement with the results of the well recognised the chevron edged types. Details of the tests, and analytical validation of the technique, are presented

Jan 1, 1992

By Heinrich Freyn

THE American iron and steel manufacturer finds himself to-clay barely at the threshold of enormous possibilities for practicing rational economy in the use of fuels. The fuel cost is by no means the smallest of items which enter into the cost of manufacture of iron and steel products, but the great wealth of this country in high-grade fuels, together with a protective tariff, has heretofore made fuel economy relatively unimportant. In Germany, the use of raw coal for the purposes of iron and steel manufacture has been all but abandoned and large sums of money, formerly irrevocably wasted, are now being saved. When scanning the literature of this country devoted to the application of gas power, but little information will be found on a subject which, however, is destined to become of considerable importance in the United States, namely, the use of coke-oven gas for the generation of power in gas engines. This lack of information can be traced to the fact that the regenerative by-product coke oven with its large amount of surplus gas is still far from having attained in this country the universal application which it has found in Europe. This statement needs hardy any corroboration other than the evidence of statistical investigations made by E. W. Parker of the United States Geological Survey, according to which only approximately 25 per cent. of the total coke produced in this country in 1912 was made in by-product coke ovens, whereas 75 per cent. was produced in bee-hive ovens. This entailed the enormous loss of over $80,000,000 in non-recovered by-products, such as gas, tar, and ammonia, without considering the substantial loss due to the non-recovery of benzol from the coal. There are two more or less distinct fields of application of the by-product coke oven: one, to furnish as the main product metallurgical coke of specified quality, and surplus coke-oven gas as the by-product, and the other, to carbonize high-volatile coals, and thus produce as the main product large quantities of gas, high in heat value and rich in illuminants, adapted primarily for domestic heating and lighting, while domestic coke becomes the by-product.

Jan 4, 1914

By G. Chi

Outline 1.Regional geologic setting 2.Host rocks and structures 3.Mineralization, alteration and paragenesis 4.Geochronology 5.Major and trace elements 6.Fluid inclusions 7.Carbon and oxygen isotopes 8.Conclusions

Apr 1, 2005

By J. L. Stokes, L. J. Demer

It has recently been shown' that epitaxial films of silicon carbide deposited on silicon single crystals possess desirable properties for semiconductor applications. There is one apparent disadvantage to such a system, however; since epitaxial deposition is a high-temperature process, it can result in plastic deformation of the silicon substrate. The accompanying Berg-Barrett X-ray diffraction photographs reveal plastic deformation in two silicon semiconductor crystals which occurred when the crystals were coated with an epitaxial layer of silicon carbide at 1150°C. Due to differences in thermal expansion between the silicon substrate and the epitaxial silicon carbide, the silicon was subjected to stresses while still in the plastic temperature range. Both crystals shown were 0.7 in. in diam and 0.0055 in. thick. The crystals were sliced from a larger crystal so that their polar axes were parallel to the [ill] direction. After cutting, the crystals were polished with diamond paste, and etched in HC1 vapor to remove surface damage re- sulting from the cutting and polishing operations. This provided clean, damage-free surfaces on which to deposit the silicon carbide. Figs. l(a) and l(b) are reflection and transmission photographs, respectively, of the same crystal. A smaller portion of the crystal is shown in the transmission geometry, because a vertical slit was

Jan 1, 1965

By M. A. Scheil

Austenitic stainless alloys are susceptible to stress-corrosion cracking which may occur under certain corrosion environments irrespective of their susceptibility to intergranular corrosion. Test samples are described for investigating stress-corrosion susceptibility of alloys for industrial equipment. A laboratory test using a solution of magnesium chloride boiling at 309 F. was found to produce transgranular cracks in several alloys investigated and in types 347 and 316 stainless steel tubing a residual stress of the order of 10,000 psi. was observed to initiate cracking. The susceptibility to stress-corrosion cracking as judged by the boiling magnesium chloride test indicates that alloys may be selected which will withstand a high stress in service Stressed specimens of stainless alloys included in a corrosion testing program will aid in determining the acceptibility of these fabricated alloys, when stressed, to the service conditions.

Jan 1, 1945

By G. S. Rice

This paper describes preliminary tests at the Bureau's Experimental Mine to determine, under conditions that may prevail in a bituminous coal-mine heading, how small a quantity of fire damp may bring coal-dust into suspension and ignite it. The results show that the explosion of as little as 150 cubic feet of an explosive mixture of gas and air containing 9 per cent natural gas may start a disastrous explosion of coal-dust. This is a very small volume, of gas, to cause such a result. Let us suppose that this amount of explosive mixture, as at the face of an entry which was 10 feet wide and the face was overcut to a depth of 6 feet and an upper layer of coal 2.5 feet thick had been removed, the recess so made would have a volume of 150 cubic feet. Furthermore, only 13 cubic feet of pure methane is needed in thin volume to produce this 9 per cent explosive mixture.

Jan 1, 1930

By Douglas A. Elkins

The unique characteristics of plasmas, their current applications, and ongoing research into new applications are described. Major technical and economic problems in application of plasma technology are discussed. Examples of potential applications of plasma in extractive metallurgy are described and evaluated. The report includes a selected bibliography of articles on plasma and related high-temperature technology.

Jan 1, 1969

By Alden B. Greninger, Alexander R. Troiano

Metallurgists have long believed that martensite in steel forms as plates along the octahedral {111} planes of austenite. Much has been written about mechanisms whereby units of the austenite lattice are pictured as transforming to martensite by shearing movements initiated along the octahedral planes of austenite, supposedly resulting in plates of martensite lying parallel to these planes of shear. A critical inspection of two or three photomicrographs of quenched hypereutectoid steel led us to the conclusion that the orientation habit of martensite, at least in hypereutectoid austenite, could not possibly be octahedral. Inasmuch as recent studies,30,31 of the martensite-type reaction in nonferrous alloy systems have established the irrational orientation habit as characteristic of this type of lattice transformation, the need for a thorough restudy of the crystallography of martensite formation in steel was evident. The present paper reports the results of such a study, extended to include both cementite and some of the products of constant-temperature decomposition of austenite. Also reported are a few of the results obtained from a microscopic and X-ray study of the austempering process in very high-carbon steel. I. The Martensite Transformation Previous Work Microstructure and Crystal Structure of Martensite.—Among the best series of published photomicrographs of quenched steels are those of Whitely,1 Robertson,2 Hanemann and Schrader,3 and Lucas.4 The crystal structure of martensite is body-centered tetragonal, with axial ratio varying from 1 near 0.0 per cent carbon to 1.08 for 1.75 per cent

Jan 1, 1940

By Alden B. Greninger, Alexander R. Troiano

Metallurgists have long believed that martensite in steel forms as plates along the octahedral {111} planes of austenite. Much has been written about mechanisms whereby units of the austenite lattice are pictured as transforming to martensite by shearing movements initiated along the octahedral planes of austenite, supposedly resulting in plates of martensite lying parallel to these planes of shear. A critical inspection of two or three photomicrographs of quenched hypereutectoid steel led us to the conclusion that the orientation habit of martensite, at least in hypereutectoid austenite, could not possibly be octahedral. Inasmuch as recent studies,30,31 of the martensite-type reaction in nonferrous alloy systems have established the irrational orientation habit as characteristic of this type of lattice transformation, the need for a thorough restudy of the crystallography of martensite formation in steel was evident. The present paper reports the results of such a study, extended to include both cementite and some of the products of constant-temperature decomposition of austenite. Also reported are a few of the results obtained from a microscopic and X-ray study of the austempering process in very high-carbon steel. I. The Martensite Transformation Previous Work Microstructure and Crystal Structure of Martensite.—Among the best series of published photomicrographs of quenched steels are those of Whitely,1 Robertson,2 Hanemann and Schrader,3 and Lucas.4 The crystal structure of martensite is body-centered tetragonal, with axial ratio varying from 1 near 0.0 per cent carbon to 1.08 for 1.75 per cent

Jan 1, 1940

By Montini A

The dynamic behaviour of the load in a pilot-scale ball mill has been measured as a function of axial position within the mill, end plate lifter design, load volume J (percent of mill volume), percent solids in the slurry S and mill speed N (percent of critical speed). Conductivity probes were inserted through the shell of the mill to provide online measurements of the dynamic orientation of the load in the mill. It was found that 1. the height of the shoulder of the load is increased by increasing J, S or N. 2. Measurements of the effect of S on the location of the shoulder of the load should be very useful in mill control strategies. 3. The axial centre of gravity of the load in the mill is not affected by operating conditions. 4. The presence of lifters on the feed end plate does not affect the torque drawn by the mill. 5. Holdup of slurry in the mill is a strong function of slurry viscosity and a weak function of mill speed.

Jan 1, 1986

F. E. BASH, Philadelphia, Pa.-In order to make a definite check on the emissivity of crucible steel under works conditions, a test was planned and executed by the plant of the Midvale Steel Co., by a Sub-committee, as follows: Five crucibles were put in a crucible furnace with-the normal charge and were treated in the same manner as a number of others that were charged at the same time; the only difference was that the five cur-cibles had lids with.2-in. holes in the center. It was thought that after the crucibles were removed from the furnace a reading could be made through the hole in the lid with the optical pyrometer and that such a reading would give the true temperature of the steel as black-body con-ditions should prevail inside the crucible. If after obtaining the true temperature, the crucible lid were removed and the steel poured into the ladle, the apparent temperature could be taken by sighting on the steel stream and the emissivity obtained from the two temperature values. Such a test was carried out with five crucibles. About a third of the crucibles charged into the furnace with the five experimental ones were first drawn from the furnace and poured into the ladle. The experimental crucibles were then drawn and readings of the true temperature were made

Jan 12, 1919

By Vijaya Bhushan Rao, Jason Redgers

The typical Vibrocompaction projects undertaken in the UAE are on reclaimed Sands. These Sands which are predominantly the crushable, calcareous, carbonate sands found locally as opposed to the more common quartz or silica sands that are featured in most design literature. The famous reclamations such as the iconic Palm Jumeirah in Dubai, often have specification for mitigation of liquefaction induced settlements, bearing capacity increases and total and differential settlement requirements. Often these performance targets are achieved by the means of achieving a particular relative density that are generally measured by a defined Cone Penetration Test, CPT targeting values of cone resistance (Qc), MPa at respective depth zones. In this paper some case studies are presented, where soil suitability for deep compaction by vibratory methods was firstly assessed for suitability using the Massarsch, 1991 compactability chart prior to the application of vibrocompaction and its subsequent evaluation. One such project named the Island Development required 17 to 23m depth of penetration only to treat the lower 5 to 6m of sand above rockhead as eventually the top 15m of sand will be further excavated to allow for the construction of basement. The paper will present pre and post CPT results, the results of initial site calibration trials and evaluation of the completed works.

Oct 1, 2022