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By D Fergusson, J D. St George

Highwall stability is a major consideration in optimising opencast mine geometry. It involves assessing the risk of those slope failures that are large enough to have significant cost, safety and/or operational implications. These risks are then balanced against the value of the resource to arrive at an acceptable slope design. Load-deformation models (commonly referred to as ænumericalÆ models) of slopes provide a powerful tool in this decision-making process since they can be verified well before slope failure occurs. This gives the slope designer increased confidence in reviewing designs during excavation, potentially allowing early revision of pit geometry to either increase or decrease safety margins as appropriate. However, these models are not always adopted as they depend heavily on an appropriate choice of constitutive model and material parameters.   A preliminary load-deformation model of a 170m highwall in Solid Energy North (SEN) OperationsÆ Awaroa 4 opencast coal mine in the Rotowaro Coalfield has been prepared. This uses a strain-dependent constitutive model based on laboratory test results, strength parameters developed by SEN and excavation monitoring data. The laboratory testing has included triaxial compression tests on large-diameter fractured samples to characterise the stress-strain response of the closely-jointed soft rock masses that exist in many parts of the mine. Data from the monitoring of a 25m cut made during excavation of a haul road has been used to refine and verify the constitutive model. The resulting highwall model has predicted highwall crest movements corresponding to the excavation of each bench, for comparison with monitored values. Key model outputs are total horizontal movements of about 0.5m near the highwall crest and shear strains of 0.5-0.7% at the locations of potential bedding-parallel shear planes underlying the highwall. Most of the movement is expected to occur as creep rather than as an immediate response to excavation.

Jan 1, 2006

By AIME AIME

As already announced in the January Bulletin, this publication will be issued during the coming year monthly instead of bi-monthly as heretofore. Among other reasons for this change, it is desired to effect thereby the earlier transmission to members of important papers, lists of candidates for membership, and other items of timely information. Spokane Meeting and Excursions. Further details of the' 97th meeting of the Institute have been sent to members in the Circular of May 8, 1909. For, convenience of the members a summary of the additional in¬formation is here presented. A special train of Pullman cars will leave Chicago about September 15. This train will be side-tracked at all places visited, and the sleepers will be available for lodging and the dining-car for meals during the entire trip, except during the Yellowstone Park tour. The general. cost of the trip per member will be $300, which includes transportation, berth, and meals for the entire trip from Chicago back to Chicago, almost 6,000 miles, and the tour through Yellowstone Park, occupying in all about 30 days. Special accommodations on the train will be furnished at the following, rates

May 1, 1909

By G. Coetzer

"Prior to operating a non-recovery coke pilot plant oven, it was essential to ascertain coal cake stability during the loading of a 1 m3 (1 m × 1 m × 1 m) coal cake into the cold pilot-plant oven by a pusher mechanism. Previously established laboratory-scale compaction parameters, to obtain coal cakes with sufficient stability, were employed during the loading tests of the coal cakes. Two different coals were evaluated, namely Waterberg semi-soft coking coal (sscc) and Oaky North hard coking coal.It was demonstrated that lower applied compaction forces (14%) can be utilized during 1 m3 compaction, in comparison to laboratory-scale tests, to obtain similar wet cake densities, owing to differences in the effect of frictional forces. Wet cake densities for Waterberg sscc improved slightly (3%) to 1.13 t/m3 when utilizing 79 t/m2 applied force for a 1 m3 coal cake, in comparison to laboratory-scale tests. Similar results were obtained for Oaky North hard coking coal, with a 6% density increase to 1.27 t/m3 at a similar applied force. Porosities decreased by 13% and 32% for Waterberg sscc and Oaky North coal, respectively, when 1 m3 compaction was compared to laboratory-scale tests. An opportunity exists to further decrease the porosities of Waterberg sscc during compaction, whereas acceptable compaction parameters were achieved for Oaky North hard coking coal. Most major vertical cracks and the partial collapse of coal cakes were mitigated, and high-stability coal cakes were obtained that could be successfully loaded into the pilot-plant coke oven by a pusher mechanism.Factors contributing to the instability of the coal cake during loading into the oven, such as vertical cracks, are (i) the cubic geometry (1 m3) of the coal cake, (ii) friction exerted by the oven floor, and (iii) mechanical problems, such as a misalignment between the pusher machine feeder plate and the oven floor. IntroductionOperation of the stamp-charging horizontal 1 t electrically heated coke pilot-plant oven at Exxaro Resources requires coal cake stability during the loading of a 1 m3 compacted coal cake into the oven. In this case, a pusher plate is utilized to push the coal cake into the oven over the oven floor. This is in contrast to a ‘spoon’ or bottom plate feeding mechanism as found in industrial horizontal coke ovens. The pusher plate loading mechanism dictates that the coal cake should possess high stability and inherent strength owing to frictional forces exerted by the oven floor. In order to obtain a coal cake of acceptable stability for the 1 t coke oven, various compaction parameters need to be verified and established."

Apr 1, 2019

By Zhigang Liang

Investigation into the mixing of 150t ladle furnace by two-nozzle jetting was performed by a water model simulation of 1:4. The effects of nozzle arrangements including separation angle, radial position and asymmetry as well as tracer adding position on the mixing time were studied. The most favorable mixing is achieved when the two nozzles are symmetrically arranged at half radii in the ladle, with 45o separation angle. The empirical relationship between the mixing time and stirring power intensity has been established for two-nozzle jetting based on the present experimental results. In addition, the swelling above bath surface is also investigated with two-nozzle jetting.

Jan 1, 2009

By M. P. Hardy

Copper-Nickel ores in northeastern Minnesota could establish a new industry in a region where underground mining has not been active. This study reviews geotechnical data relevant to the selection and design of underground mines in this region and by numerical structural analysis evaluates the importance of some geotechnical parameters to mine method selection. Because of the rapid development of computer modeling many new techniques have become available for modeling rock mass behavior in recent years. An overview of these methods is presented and their applicability to mine design reviewed. Methods included in this summary were the differential continuum models, such as finite Pint and finite difference, integral continuum models, such as boundary element, displacement discontinuity and boundary integral equation methods, and discontinuum methods such as the distinct block model. The displacement discontinuity method was used to evaluate the influence of geotechnical parameters on some aspects of mine design. Three problems; room stability, pillar stability on a weak inclined contact and sill pillar thickness influence on sill pillar stability, were analyzed to evaluate the relative importance of insitu stress field and joint properties on design. It was concluded that for stability analysis the initial horizontal stress is of most importance in all aspects of design. The position, orientation, persistence and strength of joints is also of primary concern. In a more general sense, however, it was concluded that detailed geotechnical parameters have much less influence on mine method selection than more general factors such as rock quality, initial stress state, orebody shape and economics.

Jan 1, 1978

By C. Blawert

In spite of various corrosion studies on HPDC AZ91, there is no clear indication which microstructure gives the best corrosion performance. The skin with its fine microstructure is sometimes reported to have the best corrosion resistance, but there is no clear definition of the skin. If the skin is the outermost part of the casting and nothing is removed from it, then it is contaminated and the corrosion resistance is low. If the outermost skin is removed (about 25 µm) then a better corrosion resistance can be obtained. However this does not automatically mean that there is no other region in the bulk of the casting which could have a similar or even better corrosion resistance. Indeed, the corrosion measurements including potentiodynamic polarization and long term electrochemical impedance spectroscopy (EIS) revealed a lower corrosion resistance of the original as-cast skin about 100 pm thick. The thickness of this region is more or less independent from the thickness of the casting section. The surface region is free from any dendritic grain growth which influences the amount and distribution of the 13-phase and therefore the distribution of the most important alloying element Al. This could explain the different corrosion behavior. Further reason can be found in the enrichment of some impurities such as Fe in the near surface.

Jan 1, 2006

By B. E. MacNab

During the past several years, Raymond Kaiser Engineers has prepared numerous studies concerning the technical and economic feasibility of coal exporting facilities in the western United States. Perhaps the most striking conclusion to be drawn from these efforts is that many people underestimate the complexity of the highly competitive, dynamic coal marketing system which includes coal loading terminals as an essential but relatively low-cost link in the energy production and delivery chain. The title of this paper, "The Status of Western United States Coal Ports - An Economic Assessment," should not delude anyone into thinking that the future of western U.S. coal- exporting ports has now congealed into a well- defined economic plan. As this paper will demonstrate, the situation is complex and more dynamic than ever and promises to remain so into the late 1980's.

Jan 1, 1982

By X Zhang, Y Zhu, P E. Ngoepe, P P. Mkhonto, W Xiong, L Han, L Lu

The triazine molecules have not been given much attention and they are potential collectors that may positively impact the mineral processing industry. The adsorption of triazine as collectors such as sodium 2,6-dithio-4-butylamino-1,3,5-triazine (SDTBAT) on pyrite form a basis in design of flotation collectors that may be applicable in a wide range of sulfide minerals. The SDTBAT collector was compared with the sodium normal butyl xanthate (SNBX) and sodium normal butyl dithiocarbamate (SNBDTC). All collectors were adsorbed in their neutral form containing sodium on the pyrite (100) surface. The computational calculations found that the adsorption energies followed the order: SDTBAT (-300.35 kJ/mol) > SNBX (-186.10 kJ/mol) > SNBDTC (-163.78 kJ/mol). It was observed that the SNBX and SNBDTC adsorbed through the S atoms, while the SDTBAT adsorbed through the S atoms and N atoms onto Fe atoms. It is clear that the SDTBAT had a strong binding energy which is attributed to the presence of the triazine group that is electron depositing to the active S atoms compared to the SNBX which possessed the oxygen that is electron withdrawing. Moreover, the SDTBAT collector was found to bind stronger than the xanthate. This was complimented by microflotation tests that showed fast floating and higher recoveries of pyrite when using the SDTBAT collector than the xanthate and DTC. This clearly demonstrated that the SDTBAT is a potential collector to replace the xanthate collector due to its high selectivity and flotation power.

Aug 24, 2022

By J Benn, V Kuznetsov, G Timms, A Spain

Earthen covers are now widely used in the mining industry to control the generation rate and/or release rate of low quality drainage from piles of sulfidic minewastes. Covers are usually designed to reduce the water infiltration rate and in some cases may also reduce the oxygen flux to the underlying sulfides. Engineered covers have only been used since the 1980s, however, and there is very little field data on their performance in the longer term. This lack of information has implications for the degree of confidence that can be placed on the predictions of the environmental impacts of sulfidic minewastes, for the acceptance of close-out criteria by regulatory authorities and for the financial liability of the mining industry. Covers were placed on sulfidic waste rock dumps at the abandoned Rum Jungle uranium mine during 1984 - 1985. These covers were designed to reduce the water infiltration to less than five per cent of incident rainfall by both water shedding and storage-release mechanisms. Regular monitoring by the Australian Nuclear Science and Technology Organisation (ANSTO) demonstrated that the covers performed better than the design criterion for around ten years, but infiltration rates have subsequently increased. There is a 66 per cent probability that the infiltration rate now exceeds five per cent of incident rainfall. The cover on the largest pile, WhiteÆs heap, was sampled in pits dug at eight locations. Sampling was carried out at the end of the monsoonal wet season and again at the end of the ædryÆ season. This, together with laboratory testing, enabled cover performance to be assessed against five criteria: design, construction, cover material characteristics, physico-chemical characteristics and biological characteristics. We are of the opinion that the design of the cover was suitable to achieve the objectives of stability, water shedding, storage-release, and provision of a substrate for vegetation growth. Over most of the surface of the heap, the construction of the covers, drains and erosion prevention structures was in accordance with design specifications. However, several small and localised bare patches on the upper surface of WhiteÆs heap coincide with a reduced cover thickness, which is likely to have been due to poor construction in those patches. The construction of covers on minewastes is dependent on an adequate source of material meeting design specifications. From our limited examination, it appears that there was shortage of material for each of the three zones û a lower impervious clay layer, the moisture storage-release layer and the upper erosion-resistant layer for vegetative growth. An indication of this was that the upper layers in some areas were observed to be thinner than specified. We are of the opinion that this shortage of suitable material has been responsible for some of the changes observed ten years after emplacement. Physical and geotechnical testing indicated that the cover materials no longer meet the original specifications. In particular, the permeability at the 8 locations was found to be greater than specified, by up to several orders of magnitude. The higher permeability may explain the higher observed rainfall infiltration and moisture content of the waste rock. This increased permeability appears to be due to a combination of biological and physical processes û galleries formed by termites and ants and an extensive system of shrinkage/desiccation cracks formed by the development of a polygonal blocky structure involving the entire lower clay layer. The desiccation cracks may fill with coarser illuviated materials and form a conduit through which roots access the underlying waste rock. Measurements were made of oxygen flux into the heap as cover layers were excavated in the pits. They indicated that the full cover currently reduces the oxygen flux to 20 - 23 per cent of that into bare waste and that this reduction seems to be proportional to the cover thickness. It was also found that the oxygen flux into the cover is about four times higher at the end of the dry season than at the end of the wet season and that the difference is due primarily to the difference in moisture content of the cover. Recommendations are made for the design and construction of covers.

Jan 1, 2003

By W. J. Millard

VAGUE rumors and stories have been heard, from time to time, about the diamond and gold deposits of southern Venezuela. It is perhaps appropriate, at this time of revived interest in gold mining, to publish a few facts in regard to this country, which has been undergoing exploration since the fifteenth century. Gold and diamonds are found principally in the State of Bolivar which lies in southeastern Venezuela and is bounded by British Guiana on the east and Brazil on the south (see Fig. 1). The famous Mt. Roraima is situated at a point where these three countries meet in a common point (see Fig. 2). Some gold is also found in the southern part of the territory of Amacuro. Good oil prospects exist in the northern part of this same territory. Diamonds are found on the Caroni river from Rio Paragua to the village of Guri. Another small district is on the headwaters of the Cuyuni river. Quartz veins containing gold are chiefly exploited in

Jan 1, 1931

By I. AITKENS

It is a common misconception that all yellow stones are topazes and that all topazes are yellow; but neither statement is true. The real topaz is a rather rare mineral, and a large number of yellow stones that masquerade as topaz are nothing more than yellow quartz, known as citrine, but almost universally called topaz. The true topaz is often called "Brazilian" topaz by the jeweler to distinguish it from yellow quartz; nevertheless, both terms are freely applied in trade to other yellow stones. Topaz is considered the most popular yellow stone for jewelry and is often used as the principal stone in brooches or pendants, especially in old-fashioned ornaments. However, many other species yield pretty yellow stones, some of which are far more numerous and less costly than the topaz.

Sep 1, 1931

By Mario González Ramírez

The safe transport of sour gas requires steels with enhanced hydrogen induced cracking (HIC) resistance. Centerline segregation bands of high hardness microconstituents and non-metallic inclusions are the heterogeneities usually linked to HIC failures in pipeline steels. Full-scale production heats of a new low Mn, Nb microalloyed steel were produced by different steel mills aiming at the application in sour gas environments. The new alloy design provides both effective strengthening and control of sulphide inclusions. Coil microstructure consisted of fine grained ferrite with a small volume fraction of uniformly dispersed eutectoid aggregates. Most importantly the microstructure was uniform in both the longitudinal and transverse directions and exhibited exceptional consistency. Samples from this steel were submitted to HIC testing according to NACE standards TM0284-2003 without any sign of cracking. The results, so far, confirm that this new alloy design provides the unique opportunity to economically produce a high strength pipe steel grade with improved sour service resistance for the linepipe industry.

Aug 8, 2018

By Stephen R. Iverson

Mineral deposits examined in and near the Raywood Flats RARE II area have low potential for development. The Mill Creek Mine (fig. 1), has produced about 14,000 tons (13,000 t) of marble, and another 5.5 million tons (5.0 million t) of marginal marble reserves suitable for lime, chemicals, and cement production are estimated to remain at this deposit. However, nearly all the marble is outside the study area. The deposit is marginal because alternate sources of marble are closer to markets. A tungsten occurrence in the marble is too small and low grade to be considered a resource. Ten tons (9.1 t) of uranium- and thorium-bearing material have been mined from a pegmatite dike at the St. Patrick Mine. However, this occurrence also is too small and low grade to be considered a resource. More than 400 lode and placer claims have been located in or near the study area. There are no current claims or mineral, oil and gas or geothermal leases.

Jan 1, 1983

By W. W. Adams

"The eighth National Safety Competition, that for 1932, conducted by the United States Bureau of Mines, was participated in by 322 mines and quarries operating in 34 States. Tables 2 to 6 show the relative standing of the various plants. Bronze trophies, known as the 'Sentinels of Safety,' which were provided by The Explosives Engineer magazine to be awarded annually by the Bureau of Mines, were awarded to five companies, each company having established the best accident-prevention record within one of the five classes into which all companies were divided, - namely, anthracite-mining companies, bituminous-coal-mining companies, metal-mining companies, operators of nonmetallic-mineral mines other than coal mines, and quarries or open-cut mines. The trophies are awarded for one year and are then transferred to the winners of the succeeding year's contest.The trophy for bituminous-coal mines, which has been in New Mexico for the past year, was won by a mine in West Virginia. The metal-mine trophy goes to New York State for the first time in the history of the contest. Previously it had been won by mines in Minnesota, Michigan, Kansas, and Oklahoma. The trophy for nonmetal mines remains for another year at Retsof, N. Y.; that for quarries and open-cut mines is transferred to a quarry in Michigan. The trophy for anthracite mines, of course, remains in Pennsylvania, as all anthracite mines in the contest are in that State.In determining the relative standing of the various companies enrolled in the competition, all mines and quarries were graded according to their accident-severity rates, - that is, according to the number of days of disability of employees on account of accidents in proportion to the number of man-hours of work done by all employees at the plant. Reports of accidents and of man-hours worked were furnished by the companies to the Bureau of Mines. These reports were carefully examined and classified to insure uniform weighting of accidents according to the number of days of disability to be charged and to insure uniformity of methods of calculating the accident-severity rates for the various mines and quarries. When the relative standing of all plants had been determined in this way, a summary of the records of the companies having the lowest accident-severity rates in their respective groups was sent to the members of a committee of award for examination in accordance with the rules governing the safety contest. The members of the committee of award were W. H. Cameron, managing director of the National Safety Council; William Green, president of the American Federation of Labor; James F. Callbreath, secretary of the American Mining Congress; T. T. Read, Vinton professor of mining engineering of Columbia University; C. B. Huntress, executive secretary of the National Coal Association; A. J. R. Curtis, assistant to the general manager of the Portland Cement Association; and A. T. Goldbeck, director of the bureau of engineering of the National Crushed Stone Association. When two or more mines within the same group operated without an accident during the year, the contest rules provided that the trophy for the group should be awarded to the plant whose record showed the largest number of man-hours worked."

Jul 1, 1933

By C. Haycocks

The problems caused by interaction in multi-horizon mining are world wide and are not limited to the coal industry. These problems will continue to increase as mining of new seams multiplies and replaces production from mined out horizons. Interaction problems are particularly evident in the Appalachian coal fields which contain many mineable, contiguously placed coal seams. Selection of the mining sequence of these seams, historically and currently, is based primarily on considerations of seam ownership, availability, and economics. Experience has shown, however, that mining any seam can seriously affect subsequent operations in coal seams both above and below the one being mined. This interaction effect is often detrimental to the recovery cost and safety of mining the subsequent seams. Designing to avoid or minimize interaction effects represents a major challenge to the modern coal mining industry and therefore is the focus of this research. In an effort to evaluate past interaction effects and provide guidelines for future mine design, interactive ground control problems were categorized into four areas. These are pillar load transfer, massive interseam shearing, subsidence and pressure arching effects. To facilitate research, each of these areas was studied separately although in reality these subdivisions are arbitrary and have considerable overlap.

Jan 1, 1983

By Lloyd Litwin

The ARTA 2008 Project (Alpha Ridge Test of Appurtenance) was a Canadian Government sponsored deep water seismic survey carried out on the high arctic permanent polar ice cap. This Geological Survey of Canada operation was the second seismic research project in the high Arctic and was monitored by the Danish Government. Utilizing 100% air support from Eureka and then helicopters from an ice based tent camp north of Ellesmere Island, the five week study was accomplished in the early spring just after the sun returned to the far north.

Jan 1, 2011

By H. A. Steane

"This presentation will cover some crushing and grinding considerations in plant design and operation. There is nothing basically new in the subject matter presented here; however, the viewpoint and interpretation may be novel and some of it controversial.The presentation is based on experience gained in the metallurgical design of plants for Placer Development Limited from 1960 to the present. The plants are listed on SLIDE No. 1.These plants have conventional crushing, followed by rod mill and ball mill grinding. I would like to think that autogenous grinding plants are the answer for eliminating secondary crushing plants and reducing the capital and operating costs; however, the autogenous plants seem to have some problems of their own and I have had no experience with them.Fineness of Grinding RequiredFirst let us consider the fineness of grinding required.The fineness of grind will affect the recovery obtained, and the relationship must be determined. If the grinding is too coarse, some of the valuable mineral, either free or locked in middling grains, will not be floated. However, as grinding is probably the greatest single operating cost, we do not want to grind any finer than is justified economically.Finer grinding should not be carried beyond the point where the net smelter return for the increment saved becomes less than the added operating cost. Even this fineness will be beyond the economic limit because of the additional capital cost for the equipment needed to achieve it. These factors will be discussed in more detail later.The Bond work index is the commonest method of expressing a measure of the effort that has to be expended in grinding. It is the kilowatt-hours required to reduce a ton of rock from an infinite size to 80% passing 100 microns. The formula allows a calculation to be made for other size ranges."

Jan 1, 1976

By D D. Deacon

A brief description is given of the requirements which No. 4 Shaft has been designed to meet and of the methods by which two-stage winding of rock has been accommodated in a single shaft sunk to a depth of 7,421 ft. This is followed by a consideration of the factors which led to the decision to sink the shaft as rapidly as possible. Introduction T HE No. 4 Shaft of Hartebeest-fontein Gold Mining Company, Ltd., has been sited to serve the deep southern area of the mine, some 1,500 claims in extent, between the elevations of 6,250 and 7,300 ft. below surface. From this area, some two-thirds of the mine production will ultimately be obtained. Above the 6,-250-ft. elevation, an existing shaft hoisting system, situated adjacent to the reduction plant, is of adequate capacity to cater for all ore hoisted to surface for milling. No. 4 Shaft will therefore be required to provide downcast ventilation of 1,000,000 c.f.m., together with surface hoisting facilities for men, material and development rock and underground hoisting

Jan 1, 1965

By M. Ramulu, A. K. Chakraborty, P. B. Sahu, C. Bandopadhyay, P. B. Choudhury

Human response to blast induced vibration and air overpressure is an unsolved problem that accompanies excavation process in mining. Pre-assessment and understanding of annoyance due to production blasting is probably one of the most important aspects of a successful mining operation. Complaints arising due to unoptimised blasts lead to various critical situations that hamper production. Inspite, this important aspect has been covered by a limited number of researchers in the world and probably least in Indian context. Human response is a complex phenomenon and the sensitivity of individual also vary from person to person depending on various factors like age, sex, literacy, health and exposure to mining. With ever increasing demand of minerals, opencast mines are expected to approach habitats and thus mine management may witness increased response to blasting. Many developed countries have their own guidelines based on scientific analysis, addressing such environmental problems, where as there are a few studies available in India. This study introspects above phenomenon in tune with mining requirements by analysing direct human response. This paper is based on a case study regarding the human response to blast induced hazards in a Manganese mine situated in central India. Advanced techniques of Critical Path Method and Multiple Response Analyses have been used to unearth important inferences on the response of different crosssections of population residing about the mine to blast induced noise, ground vibration and air overpressure. Various inferences drawn may provide guidelines to the planners, environment or safety departments and blasting official for safe and environment friendly blast design.

Jan 1, 2004

By R. D. Pehlke, J. V. Gluck

AS a portion of a general study of liquid-metal thermodynamics, high-temperature galvanic cells were used to study the effect of added dilute solutes on the activity of zinc in dilute solution with molten bismuth in the range 450° to 650°C. 1,2 The cells were of the type The experimental procedures have been described previously.1 In the course of studies conducted in the bismuth-rich corner of the systems Bi-Zn-Au and Bi-Zn-Cu, marked discontinuities were observed in the electromotive force-temperature relations for a number of the experimental compositions. Above the discontinuity temperatures, the relations, which were linear, exhibited slopes similar to the binary alloy of the same mole fraction zinc, as shown in Figs. I and 2. Below the discontinuity temperatures, the slopes were markedly different, but the relations remained linear. In general, as the amount of the third eletnent was increased, the slope of the lower portion of the relations tended to become less positive. The slopes of electromotive force-temperature relations reflect the entropy of mixing of zinc and, therefore, the occurrence of a discontinuity marks the transition between two different equilibrium situations involving the solution of zinc. A number of other investigators3-5 have used such observations to determine liquidus boundaries in binary alloys. Since the upper portions of the ternary electromotive force-temperature relations of this study had the same slopes as the binary alloys, the discontinuities are interpreted as marking the transition between the single-phase liquid region and the underlying two- and three-phase regions. Reference to the Zn-Bi equilibrium diagram6 confirms that the binary alloys were single-phase liquids at the experimental temperatures. Fig. I shows the electromotive force-temperature relations for the alloys containing Bi-Zn-Au and Fig. 2 shows similar relations for the Bi-Zn-Cu alloys. In the lower portion of each figure, the temperature of the discontinuity is plotted vs the mole fraction of the added solute at the various levels of zinc concentra- tion. Cross-plots from these curves at constant temperature permitted the construction of the partial liquidus surface isotherms shown in Figs. 3 and 4.

Jan 1, 1967