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By Mike Broczkowski, Laura Dewhirst, Kieran Large, Angelo R. Fernando, Heather Daigneault, Jim Johnson, Randy Wiens

The radioactive isotope radium 226 is a contaminant of potential concern in effluent waters from metal mining operations in Canada. Acceptable release levels of radium 226 are governed by Metal and Diamond Mining Effluent Regulations. Since radium is invariably present as a companion element in uranium ore, monitoring and controlling of radium 226 is a must for uranium mining operations. Measurement of radium 226 is traditionally carried out through a radiochemical technique involving selective co-precipitation of radium with barium sulphate followed by alpha spectroscopy for quantification. As of 2010, Cameco has also been using an ICP-MS based radium analysis method developed in collaboration with a research team at Trent University, Peterborough, Ontario. This method, which is highly automated and requires significantly less sample handling, with improved turn-around-times, is being used by Cameco site laboratories at the McArthur River and Cigar Lake mines as well as the Port Hope Conversion Facility. This paper compares the benefits and drawbacks of this new method, compared to the traditional alpha counting procedure drawing from almost ten years of field experience.

Jan 1, 2020

By J. C. Rudolph

"THE TOPIC on which I am speaking this afternoon is ""The Future of the Canadian Oil Industry.'' At the time of C + 100, we should take a searching look at ourselves, an honest appraisal of our achievements and a forthright accounting of our shortcomings as well as the uniquely Canadian aspects of this industry. I would like to put before you some of my views on the direction we are taking in the exploration field and in the production field. I would also like to speak briefly on some of our problems and the role of the various segments of our industry in solving these problems.First of all, let us look at the exploration picture. We are in the midst of an exploration boom. There were 133 seismic crews active in Western Canada this winter, the highest since 1957, land prices are appreciating rapidly, Canadian oil reserves increased + 16 per cent during 1966, there is a great demand for technical personnel of every kind and the whole industry, except the drilling segment, seems to be prospering. This surge of activity has its roots in two major occurrences. The first of these was the change in the pro-ration system in Alberta, the major producing province, accompanied by the change in spacing pat-terns. The proration change was designed primarily to encourage in-creased exploration and it has certainly had this effect. It has also had the unforeseen effect of put-ting everyone into what we, in the oil business, call ""elephant hunting."" In other words, the days of the development of barely economic, marginal fields are over. Oil companies today are only interested in high-reserve, high-productivity, high-quality reservoirs."

Jan 1, 1968

By L. J. Cunningham

I THINK it can be safely said that no mining operation, whetl1er open-pit or underground, is ever entirely free of water. It follows that every ton of ore bears a charge which represents, either directly or indirectly, the cost of keeping the mine workings as dry as possible. Water problems occur in all phases of mining operations. They cause difficult and costly drilling conditions during the exploration stage, they often seriously delay mine development, they can slow mine production and reduce efficiency, and they are a continued burden over the life of the mine. It is therefore in the interest of all mining men to be familiar with the methods and materials used for grouting. The most common grouting material is cement. Cement grouting is old and well established, and many engineers are familiar with its uses and limitations. The technique of cement grouting is relatively simple and fairly well understood, and the materials utilized are relatively in-

Jan 1, 1962

By Horace Freeman

"IN THE writer's opinion, the most important industrial re-search problems in Canada concern development of technology for the treatment and commercial utilization of the recent discoveries of v.ast quantities of easily concentrated iron ores in both eastern and western Canada. They exist in both magnetite and hematite forms. The subject is doubly important because of the lack of metallurgical coking coal in Canada. Methods for utilizing our lower grade eastern and western coals for reduction purposes must be developed. We are fortunate in our supplies of oil and gas, which can supply the heat requirements for processing or for thermal electric plants, which are now competitive with hydro-electric plants in the industrial areas. These are among the reasons which have prompted the writer to continue the development of the co-current rotary kiln direct-reduction process outlined •in his report to this Institute at the 1956 Annual Meeting ( 1) in the face of the scepticism which has surrounded the numerous costly failures in 'sponge' or 'direct' iron production. The work involved in bringing the concentrating ores of Canada to the metallic state involves, firstly, concentration of the ores; secondly, preparing the concentrates for reduction; thirdly, reduction of the 'reconstructed' ore; and finally the steel making process. These briefly will be dealt with in order, giving emphasis to the most important of these steps, the reduction process which is the main subject of this paper."

Jan 1, 1959

By A. A. Brant

"Improving geological and geophysical evaluation should serve to reduce the early-stage risk assessment and there-by contribute to exploration expenditure stimulation. The limitations of present-day methods are reviewed, particularly as to anomaly causes, depth penetration and quantitative physical interpretative abilities. Some of the problems now under study are discussed. Future developments expected include the treatment of quantitized geologic and geophysical data, as well as continuing attempts toward computerized interpretation."

Jan 1, 1967

By C. J. Hodgson

"IntroductionThe Kitsault molybdenum mine is located 600 m above sea level on Lime Creek at the head of the inlet of Alice Arm, 140 km northeast of Prince Rupert, British Columbia (Fig. 1). The area of the mine is characterized by rugged topography and deeply incised creeks which drain into the Portland Canal - Observatory Inlet fjord system. Access is by air service or boat from Prince Rupert, or by secondary road from Terrace.HistoryThe deposit was first staked in 1911, at which time the main feature of interest was a polymetallic vein with values in silver located southeast of the molybdenum deposit (Woodcock and Carter, 1976). Turnbull (1916) was the first to describe the extensive zone of crisscross quartz stringers with Mo~ on the banks of Lime Creek which, although it clearly had the potential to contain a major deposit, was not then believed to be of commercial value.Following sporadic work through the 1920s and early 1930s, the ground lay idle unti11959 when Kennco Explorations (Western) Ltd. commenced a program of systematic diamond drilling on the stockwork-type mineralization adjacent to Lime Creek. In late 1964, Kennco announced the presence of an orebody of 36 million tonnes averaging 0.230Jo Mo~ which was to be put into production at a rate of 5450 tonnes per day under a new subsidiary, British Columbia Molybdenum Ltd., at a forecasted capital cost of $20 million (revised to $30 million).Between January 1968 and April 1972, 10.4 million kg of molybdenum were produced from 9.3 million tonnes of ore, at an average mill recovery of 90%, and with an average mill head grade of 0.206% Mo~. The ore was mined in an open pit with a waste to ore stip ratio of 1.5 to 1. The. operation was terminated in 1972 due to weak molybdenum prices and escalating costs.In May 1973, the deposit was purchased by Climax Molybdenum Corporation of British Columbia, Limited and in 1979 transferred to affiliate Amax of Canada Limited. In early 1979, following completion of detailed feasibility studies, Arnax commenced construction of the 10 900 tonne per day Kitsault mine and mill complex based on a mineable open pit reserve of 95 million tonnes at an average grade of 0.192% Mo~, sufficient for a mine life of 25 years. The original capital cost estimate was $143 million; it subsequently escalated to approximately $200 million."

Jan 1, 1995

By T. G. Joseph, A. Sharma

ABSTRACT: Ultra-class haul trucks operating in oil sand face operational and maintenance issues as a result of soft underfoot conditions (Joseph, 2002). With exposure to frequent high g loading events, tire life is reduced due to sidewall belt fexure and frequent ground contact. Therefore, an improved under-standing of the interaction between tires and oil sand is needed. This paper examines the outcomes of a series of static and cyclic loading tests, performed using a scale tire on rigid, sand, and oil sand surfaces. Geometric predictions are made regarding the footprint area and vertical deformation of an ultra-classtire on similar surfaces.

Jan 1, 2011

By X. -G. Chen, K. Liu, N. Parson

"Precipitation-strengthening 6xxx alloys are widely used for building and construction and automobile industries due to their high strength, good weldability and corrosion resistance. However, their elevated-temperature properties (250–300°C) decrease rapidly due to the fast-coarsening of precipitates. On the other hand, dispersoid-hardening is one of the most efficient approaches to improve the elevated-temperature properties. Therefore, the evolution of dispersoids during heat treatment in Al-Mg-Si-Mn alloys was investigated in the present work. Various heat treatments with temperatures ranging from 300–500°Cfor up to 24 hours were performed. Electrical conductivity and microhardness were measured while optical and scanning electron microscopy combined with image analysis, were used to characterize the dispersoids. Special emphasis was placed on the evolution of the size and number density of the dispersoids under different heat treatment parameters. It was found that dispersoids started to precipitate at 350°Cfor 1 hour. Nucleation and growth were the main mechanisms at temperatures up to 400°Cwhile coarsening occurred at temperatures above 450°C. The quantitative results indicated that dispersoids precipitation reached the optimum condition after treatment at 400°Cfor 2–4 hours with a fine size and high number density, resulting in the highest hardness.INTRODUCTIONThe precipitation-hardening 6xxx aluminum alloys with major alloying elements of Mg and Si are one of the most widely used aluminum alloys for building and construction and automobile industries (Dinaharan & Murugan, 2012). In recent years, there have been increasing demands for aluminum structural components to be used at elevated temperatures (250–300°C) for different applications. However, the mechanical properties of 6xxx alloys at elevated temperature are typically reduced due to the rapid coarsening of precipitates at 250–300°C. It has been reported that the yield strength (YS) of AA6061 in the peak-aged condition drops from 276 MPa at room temperature to only 30 MPa at 315°C(Kaufman, 1999). Therefore, it is a key concern to improve the elevated-temperature properties of 6xxx alloys to expand their range of applications."

Jan 1, 2018

By E. C. Sanford

A laboratory-scale batch extraction unit and operating procedure for studying the hot-water separation of bitumen from Athabasca tar sands are described. The extractor evolved from earlier units and has been in use by Syncrude Research for the past 10 years. By using a unit such as this, it is possible to study tar sand feed quality and the effects of chemicals on the hot-water extraction process, while process variables are held constant. Data are presented to demonstrate the importance of surfactants to the process and the interrelated role of inorganic bases and surfactants.

Jan 1, 1979

This paper generalizes open stopes into elliptical cross sections and applies the results of calculations based on the mathematical theory of elasticity to indicate stress distribution on the boundaries of such stopes. These show both compressive and tensile stresses and provide an ex-planation for the development of excessive dilution in shrinkage toping. Introduction T HE stress pattern around shrinkage stopes is identical with that around other stopes under the same physical conditions. However, a shrinkage stope ends as an unsupported open stope, and the method i limited to the stress range within which the rock is generally self-supporting. If it is acceptable to generalize the outline of a shrinkage stope into an elliptical cross section, then the graphs of Geldart & Udd (1) (see also Panek (2) and Denkhaus (3)) provide a good base for approximating the stress distribution as mining progresses. However, with failure conditions in the walls, the axis ratio, as cut

Jan 1, 1964

By N. B. Brown

ABSTRACT The effect of a low4emperature stress relief at 232.2°C. (450°?F.) on the fatigue properties of shot-peened SAE. 1080 steel has been investigated. Specimens of the steel were first annealed. One half of the steel bars were then normalized and the other half were water-quenched and drawn. Specimens of the steel with each heat treatment were tested in tensile, notched bar impact, and fatigue. The fatigue specimens were test in air and water in R. R. Moore high-speed rotating bending machines in the following conditions: un-peened, peened, and peened-and stress-relieved at 232.2°C. ( 450°F.) The 'endurance life' and fatigue properties of specimens given a stress relief heat treatment after shot peening were superior to those of specimens given a smooth machine finish or shot peened. INTRODUCTION THIS investigation was initiated to obtain preliminary information on the effect on the fatigue resistance of shot peening the machined surface of a high-carbon steel similar in composition to that used in hollow drill steel. The data obtained in this investigation could be applied in analysing the application of shot peening hollow drill steel shanks. It is well known that the 'endurance life' and fatigue limits of steel are greatly ?improved by shot peening. References to this in the literature are numerous.

Jan 1, 1951

By R. M. de Carvalho

Empirical and phenomenological models of SAG and AG mills have dominated the scene for the last few decades, being used nearly every time a mill is scale-up or an attempt is made to improve its performance. However, in spite of their success, these models fail to describe the details of both the grinding environment and the breakage mechanisms. The result is a generally good track record, with a few – but very important – instances when these models fall short in their predictions, which can be very costly. Further, nearly all of these models require detailed calibration to industrial and pilot plant data, being costly in their application, although still with limited predictive capabilities. Recognizing these challenges, a new model framework has been proposed which overcomes the limitations of currently used models by coupling the microscale population balance model, the discrete element model and functions that describe internal classification at the mill grate. This model framework has already been applied to describe breakage in ball mills, with showing very promising results. However, in the case of SAG and AG mills a much greater level of complexity is involved in the model, given the interaction between the mechanical environment that is formed totally or, in part, by the ore itself, and the breakage response in the mill. The paper describes the model framework, demonstrating how it can address appropriately effects such as mill speed, mill filling and size distribution, on the response from the mill. Some of the advantages of the model are related to its intrinsic multi-component and dynamic nature, which allows simulating appropriately mixtures of ores of different competences in a transient manner.

Jan 1, 2012

By W. J. Wright

Summary Statement The following notes on the geology of the Grand Lake coalfield are intended to be introductory to a second paper being read at this meeting, which paper will describe the earlier and the more modern mining methods. The coal industry of the Grand Lake coalfield is centred chiefly within a three-mile radius of Minto, but minor operations are dotted over an area of approximately 50 square miles extending easterly to the vicinity of Chipman and Coal Creek (see Figure 1). The coal comes from one seam of Pennsylvanian age. The seam varies in thickness from 16 to 30 inches and lies almost horizontal at depths of 0 to 125 feet. It has been mined and prospected over an area of approximately 150 square miles, but in a portion of this area the commercial possibilities have been destroyed by erosion. The industry is the oldest of its kind in North America, but it did not at tract particular publicity until about 1914. Since that date, mining methods have improved and the output has rapidly increased until, in 1934, it amounted to 271,335 long tons, and furnished employment for about 1,000 men (1). Approximately 73 percent of this amount was produced by the Minto Coal Company, the Miramichi Lumber Company, the Avon Coal Company, and Welton and Henderson, and 25 per cent by the Rothwell Coal Company, Harvey Welton Limited, G. H. King, the Reade Construction Company, and the Newcastle Coal Company. The remainder was produced by J. W. Carter, G. D. Crossman, T. H. Swift, C. S. Yeamans, and several other small operators. The coal is won by underground mining, except in the case of the Reade Construction Company, and a minor operation by Ashfield and Pieton, who have employed open stripping. It is mined only as required to fill definite orders, and is loaded directly into cars for shipment. In 1934, the larger mines did not operate full time, and the production could easily have been increased if markets had been available. The coal is sold in four grades: screened or lump, run of mine, slack, and stripping. The chief market is with the railways and commercial plants, with a fair amount for domestic purposes.

Jan 1, 1935

By S. P. Cashin, D. Kashuba, W. Esplin

Barrick has had 6 autoclaves in operation at the Goldstrike Mine, North of Carlin Nevada, since 1993. The 6 autoclaves operate in parallel, processing slurry of gold ore. The gold in the ore is predominantly associated with, and encapsulated by, sulphide minerals. It is necessary to oxidize at least 90% of the sulphide mineral before the gold can be concentrated using a cyanide/carbon-in-leach (CIL) circuit. Sulphide oxidation chemical reactions occurring in the autoclaves are exothermic; however, the sulphide content in the ore is not high enough to operate the autoclaves in an auto-thermal mode. Heat from steam is added to the first 2 of 5 autoclave compartments to initiate the sulphide oxidation reactions. The steam used to heat the autoclaves is supplied by three boilers, which are fuelled with propane gas. The completion of a few operations and maintenance projects in the last 2 years has resulted in a 50% reduction in propane energy requirements. The autoclave operating temperatures were minimized. Excess oxygen addition was held as low as possible. The material of construction for the compartment walls inside the autoclaves was changed from brick to Titanium metal. And, the speed of the autoclave slurry agitators was increased. All of these activities had an impact on the propane energy requirements of the autoclaves. Presented below is a description of the autoclave systems, and a discussion of how the energy needs were reduced, resulting in significant operating cost savings.

Jan 1, 2004

By J. J. Barakso, C. Tarnocai

This paper outlines a method of testing for the mercury content of rocks, soils and plants. Techniques of sample collecting are described and the analytical procedures outlined. Examples are given of mercury determinations in two known mineralized areas in British Columbia - Copper Mountain Mines and Pacific Nickel Mines.

Jan 1, 1970

By E. A. Hart, J. E. Gill

"The property of Arntfield Mining Corporation, formerly Arntfield Gold Mines, Limited, covers an area of 2,110 acres and lies in Beauchastel township, western Quebec. The Francoeur mine lies to the west, and to the east are the West Wasa and Wasa Lake properties.The property was staked in September, 1923, by the late F. S. Arntfield. The early surface work was concentrated in the west part of the property along the Francoeur-Arntfield shear zone. The zone was opened by No. 1 shaft, which was sunk for an inclined depth of 250 feet. A series of silicified lenses were discovered farther east, where No. 2 shaft was later raised to the surface. A third shaft explored a shear zone about 1,900 feet to the east, where No. 3 shaft orebodies were developed.The mill was built at No. 3 shaft and production commenced in July, 1935, at 125 tons a day. This was increased to 280 tons by 1938, and later to 350 tons. The mine continued operations on this scale until April, 1942, when the exigencies of war necessitated closing. The Company was reorganized in 1944 and underground development was resumed in June, 1945. The total value of gold and silver produced to April, 1942, was $2,011, 755 from 529,987 tons of ore.ROCK TYPESThe area is underlain by highly deformed and altered Keewatin volcanics overlain by little deformed Cobalt sediments along the south boundary. The lavas in the vicinity of the mine workings are rhyolite, trachyte, andesite, and a flow breccia of intermediate composition. The fragmentals range from fine, well-bedded tuffs to coarse agglomerate in which acidic and basic horizons can be distinguished.The intrusive rocks are diorite and quartz-feldspar porphyry in the form of stock and sills, and narrow dykes of mica lamprophyre and syenite porphyry."

Jan 1, 1954

By Takayuki Takasugi, Naoya Masahashi, Yasuyuki Kaneno, Satoshi Semboshi, Yusuke Kadoi

Cu–Ti alloy wires doped with and without a small amount of Ni were fabricated by over-aging and using intense drawing procedures. For both the Cu–Ti alloys with and without Ni doping, the over- aged microstructure was occupied fully with a coarse lamella of Cu solid solution and β-Cu4Ti plates precipitated discontinuously by grain boundary reactions. The full-lamellar microstructure was developed much more rapidly by aging in multi steps at 873 K to 723 K rather than by isothermal aging at 723 K. Ni doping in Cu-Ti alloy was also effective to accelerate the formation of the lamellar microstructure. When drawing the over-aged alloy with inferior hardness but superior electrical conductivity, the strength increased steadily and eventually exceeded that for the wires drawn from the peak-aged alloy. In addition, the electrical conductivity of the wires drawn from the over-aged alloy was always much greater than that from the peak-aged alloy. Eventually, the procedure of over-aging, followed by intense drawing, could enhance both the strength and electrical conductivity of Cu-Ti alloys, whichever they contain a small amount of Ni or not, rather than the conventional peak-aging and drawing process. INTRODUCTION Cu-based alloy wires, which have an excellent combination of strength and electrical conductivity, have attracted extensive attention for highly mechanically stressed electrical devices, such as conductive lead wires and wires in suspension springs. Cu-Be alloys are widely used for such electrical components owing to their combination of strength and electrical conductivity among industrial Cu-based alloys. However, since beryllium is potentially toxic and also a rare element, substitute materials for Cu-Be alloys have been searched for several decades. Age-hardenable Cu–Ti based alloys have been proposed as candidates because their mechanical and physical properties are comparable to those of Cu-Be alloys; however, their electrical conductivity is inferior (Datta & Soffa, 1976; Soffa & Laughlin, 2004). In order to satisfy the requirement of downsizing and streamlining electrical devices, further improvement of the mechanical and electrical properties of Cu–Ti alloy wires is needed. Age-hardenable Cu–Ti alloys, which contain approximately 3 to 6 at.% Ti, are typically prepared using a solid solution treatment above 1100 K and then aging at a moderate temperature of 700 K to 800 K. It has been revealed that the microstructural events during aging progress as follows (Soffa & Laughlin, 2004): (1) compositional modulation of the parent supersaturated Cu solid solution in an initial aging stage (Laughlin & Cahn, 1975), (2) continuous nucleation and growth of fine needle-shaped precipitates of metastable β’-Cu4Ti with a tetragonal structure in a peak-aged stage, and (3) discontinuous precipitation of cellular components laminating the plates of a terminal Cu solid solution and stable β-Cu4Ti with an orthorhombic structure at the grain boundaries in an over-aging stage. It has been also accepted that the highest number density of dispersed fine β’-Cu4Ti needles should contribute to maximal strengthening. On the other hand, decease of the strength in the over-aging stage occurs due to the replacement of the fine β’- Cu4Ti needles with cellular components containing coarse β-Cu4Ti plates, while the electrical conductivity is significantly enhanced due to the depletion of solute Ti in the Cu matrix. This suggests that a combination of strength and electrical conductivity for age-hardenable Cu-Ti alloys is in a trade-off relationship, and that innovative improvement of both properties might be limited to tuning the aging conditions.

Jan 1, 2019

By Michel David

"The usual complaint of mines is that grade does not match exploration expectations. Quite often, more tons are mined than expected but at a lower grade. This can be seen as dilution. Geostatistics can help predict which dilution can be expected both in terms of grade and tonnage for different mining methods.The usual vocabulary of geostatistics speaks of block distribution; block variance, size effect, information effect, all terms which say very little to the practitioner. In f act, all this can be rephrased in terms of dilution .In this paper, the following is presented - an example which shows how reserves change with the size of selection units and number of samples taken, and tables which show the dilution that are bound to happen when dealing with the commonly encountered log-normal distribution. Finally, the paper shows how grade tonnage computations should be made in the case of an arbitrary distribution. IntroductionGeostatistics progresses more and more rapidly if one judge s by the number and quality of papers published in Mathematical Geology or at APCOM meetings. More and more case studies describing successful applications are published (David et al., 1986)(Kwa and Mousset-Jones, 1987). It is estimated that more than 270/0 of the gold mines around the world use geostatistics. There is still, however, a lot of resistance from the remaining 73%. Geostatistics has more formulae and equations than it needs to reach year 2000. We will be well into the third millenium before all the models available now are actually used. The progress may come in the form of finding better ways to present known statistical results and getting away from the jargon of geostatisticians. One example may be in trying to explain how we can answer the most common plea of the mining industry: production grade is not what was expected in the feasibility study."

Jan 1, 1988

By Godfrey W. McDonald, Dennis E. Fredrickson

"Commercial coal mining has been recorded in Nova Scotia since 1863 and during this period an estimated 60,000,000 short tons of mine discard containing 10 1030% coal has been accumulated, Approximately 70% of these dumps are in the Cape Breton region and most are owned by the Cape Breton Development Corporation (CBDC), formerly DEVCO.The explosion of oil produced energy costs which created an increase in thermal coal demand as well as the desire to rehabilitate abandoned mine dumps encouraged coal reclamation. CBDC was receptive to a proposal from the Selminco Joint Venture and encouraged the building of the Princess Recovery Plant (1980) and The Summit Plant (1982).The mine dump contains scrap, waste rocks, coal and substantial quantities of fine shale. The scrap and oversize are removed and the remaining material slurried with water to a density of 1.45. The slurry is cycloned to separate the saleable thermal coal from the rejects which are returned to designated areas of the dump for contouring and revegetation.BackgroundThe recorded coal production in Nova Scotia from 1863 to 1980 was 390,000,000 short tons. This extraction was associated with an estimated 60,000,000 short tons of discarded material. This mining discard and coal washing plant reject are located in numerous, varying sized dumps throughout the mining areas. Approximately 70% of these dumps are in the Sydney coal field region of Nova Scotia. The coal content of these dumps varies from 10 to 30% coal with an average of 18%.Energy CostsThe explosion o f energy costs in the mid-1970s greatly increased the sale price of thermal coal which made recovery of coal from some of the dumps economical. The environmental benefit of these operations will be the rehabilitation of the dumps upon cessation of the coal reclamation operation."

Jan 1, 1983

By J. U. MacEwan

Introduction The equilibrium between copper, zinc, and chlorine may be considered as the simultaneous equilibrium of the two separate chemical reactions of formation of the stable chlorides of copper and zinc at the temperature of the reaction i.e., l440°K. (1,167°C., 2,133°?F.)§ [Zn(g) +Ciz(g) ZnCl2z(g). ... (1) ] [2Cu(l)+Cbi'g) Cu2Cl2(l 1 ....... (21 ] Subtracting, [Zn(g) +Cu2(Clz(l i ZnClz(g) +2Cu!l) ... . (3) ] If this reaction is carried out with a copper-zinc alloy at some constant temperature above the melting point of brass, and at a total pressure of one atmosphere, the equilibrium concentrations obtained will depend on the free energy decrease .of the reaction as written in (3) and on the activities of the various components in. the reaction mixture. If the equilibrium is examined from the point of view of the phase rule, it is a three-component system, and if it exists in two phases (liquid and gas) it will have three degrees of freedom. If the restrictions of constant temperature and pressure are imposed, the degrees of freedom are reduced to one. This means that, in a two-phase system under these conditions, each different alloy phase will be associated with a gas phase of constant composition.

Jan 1, 1951