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By R. P. Carreker, R. L. Fullman, J. C. Fisher

THE existence of the phase TiAg has not been reported previously. Other investigators have denied the existence of compounds in the Ti-Ag system.13' However, phases of equi-atomic proportion have been reported by Raub, et al.' in the (similar) systems of titanium with gold and copper and zir- conium with silver. Raub's work indicated that titanium and silver are immiscible in the liquid state. No evidence of this was found although a very wide melting range exists which makes the preparation of homogeneous alloys difficult. TiAg is apparently formed by a peritectic reaction between /3

Jan 1, 1954

By A. G. Roach

This paper deals with a plant built under joint agreement between the Canadian and United States Governments to supply the strategic mineral, corundum, at a time when African production was dwindling and war demands still increasing. The operation began in September 1944, retreating the tailings from a former mill by gravity methods, and is still in production (Sept. 1946). In 1942, when it became apparent that South African production would be insufficient to meet mounting wartime requirements of corundum, a survey was made of Canadian sources of the mineral, at the request of the Foreign Economic Administration of the U. S. Government. The investigation' indicated that the quickest and cheapest supply would be obtained by reworking the tailings deposit at Craig-mont, Ontario. Sampling of the dump by Canadian Government engineers revealed that 125,000 tons of tailings, averaging 2.96 pct corundum, was available for retreat-ment. Ore-dressing tests on representative samples of the deposit were conducted by the writer in the laboratories of the Industrial Minerals Section of the Department of Mines and Resources at Ottawa; and gravity concentration on tables was indicated as the most suitable method of treatment. Decision to proceed with the project was deferred until May 9, construction was begun on May 18, and tune-up operation of the plant begun on Sept. IS, 1944. Corundum—Its Properties and Uses Corundum is an oxide of aluminum having the formula Al2O3. Its outstanding characteristic is its great hardness; 9 in the Mohs scale. In this respect it is second only to the diamond. It usually occurs in barrel-shaped crystals in nepheline syenites and other feldspathic rocks deficient in silica. It has a specific gravity of 3.95 to 4.1 and is insoluble and infusible. In color it ranges from white, through red and green, to black. Ruby and sapphire are gem varieties of corundum. Corundum is supplied to industry as closely graded grain.= The coarser roducts (10 to 24-mesh) are used largely for snagging wheels in the steel-castings industry, while the finer grades (from 70-mesh down to flours) find a wide application in the polishing of lenses and for other uses in the optical trade. All sizes of corundum grain are in close competition with synthetic abrasives such as carborundum and alundum. In some fields of application the artificial product is superior to the natural grain but not in' all. The shape of the particle and its behavior under conditions of actual use determine its sphere of employment. The United States is the largest 'Onsumer of corundum, annual consumption in peacetime approaching 3000 tons; during the war this figure was roughly doubled. During the years 1902 to 1913, the bulk

Jan 1, 1948

By A. G. Roach

This paper deals with a plant built under joint agreement between the Canadian and United States Governments to supply the strategic mineral, corundum, at a time when African production was dwindling and war demands still increasing. The operation began in September 1944, retreating the tailings from a former mill by gravity methods, and is still in production (Sept. 1946). In 1942, when it became apparent that South African production would be insufficient to meet mounting wartime requirements of corundum, a survey was made of Canadian sources of the mineral, at the request of the Foreign Economic Administration of the U. S. Government. The investigation' indicated that the quickest and cheapest supply would be obtained by reworking the tailings deposit at Craig-mont, Ontario. Sampling of the dump by Canadian Government engineers revealed that 125,000 tons of tailings, averaging 2.96 pct corundum, was available for retreat-ment. Ore-dressing tests on representative samples of the deposit were conducted by the writer in the laboratories of the Industrial Minerals Section of the Department of Mines and Resources at Ottawa; and gravity concentration on tables was indicated as the most suitable method of treatment. Decision to proceed with the project was deferred until May 9, construction was begun on May 18, and tune-up operation of the plant begun on Sept. IS, 1944. Corundum—Its Properties and Uses Corundum is an oxide of aluminum having the formula Al2O3. Its outstanding characteristic is its great hardness; 9 in the Mohs scale. In this respect it is second only to the diamond. It usually occurs in barrel-shaped crystals in nepheline syenites and other feldspathic rocks deficient in silica. It has a specific gravity of 3.95 to 4.1 and is insoluble and infusible. In color it ranges from white, through red and green, to black. Ruby and sapphire are gem varieties of corundum. Corundum is supplied to industry as closely graded grain.= The coarser roducts (10 to 24-mesh) are used largely for snagging wheels in the steel-castings industry, while the finer grades (from 70-mesh down to flours) find a wide application in the polishing of lenses and for other uses in the optical trade. All sizes of corundum grain are in close competition with synthetic abrasives such as carborundum and alundum. In some fields of application the artificial product is superior to the natural grain but not in' all. The shape of the particle and its behavior under conditions of actual use determine its sphere of employment. The United States is the largest 'Onsumer of corundum, annual consumption in peacetime approaching 3000 tons; during the war this figure was roughly doubled. During the years 1902 to 1913, the bulk

Jan 1, 1948

By Frank Somogyi, Donald H. Gray

Techniques for in-situ dewatering of tailings and slimes include evaporation, decantation, drainage under self weight, drainage by surcharging, and electro-osmosis. A promising technique for increasing drainage efficiency is a vertical, wall-drain system, which can be constructed in an impoundment concurrently with deposition of slurried tailings. The vertical drains, which can be constructed from sand or from the coarse fraction of a tailings stream, greatly speed the rate of consolidation of the fine tailings or slimes. The performance of a wall drain system and the semitidy of consolidation efficiency to certain variables or system parameters are examined. These parameters include the slime deposition rate, ratio of drain to slime permeability, drain width, and drain spacing.

Jan 1, 1979

By J. R. Thoenen

THE proper classification of mining methods has received the earnest study of many mining engineers and has resulted in much technical con-troversy, depending no doubt upon the point from which classification is viewed or the use to which it is put. So far as the writer is aware, the discussion has invariably centered around the classification of under-ground mining methods, and only superficial attention has been directed to surface methods. Volume 72, page 10, of the Institute TRANSACTIONS, presents such a classification, sponsored by the Mining Methods Committee of the Institute. A similar classification by Prof. Hugh P. Nicholson appeared in MINING AND METALLURGY in October, 1934. The two classifications are quite different in their treatment of underground methods but are identical in classifying surface methods, although Professor Nicholson does suggest possible further divisions for surface mining and admits that such subdivision is more difficult than appears at first. Surface subdivisions as given by these two authorities are as follows, showing that in spite of rearrangement the two classifications are identical:

Jan 1, 1935

New York Meets first Wednesday after first Tuesday of each month. DAVID H. BROWNE, Chairman. PERCY E. BARBOUR, Vice-Chairman. A. D. BEERS, Secretary, 55 Wall St., New York, N. Y. C. A. BOHN, Treasurer. Boston Meets first Monday of each winter month. W. E. C. EUSTIS, Chairman. - R. L. AGASSIZ, Vice-Chairman E. E. BUGBEE, Secretary-Treasurer, Mass. Inst. of Technology, Boston, Mass. ALBERT SAUVEUR, H. L. SMYTH. Columbia Holds four sessions during year. Annual meeting in September or October. STANLY A. EASTON, Chairman. FREDERIC KEFFER, Vice-Chairman. LYNDON K. ARMSTRONG, Secretary-Treasurer, P. O. Drawer 2154, Spokane, Wash. D. C. LIVINGSTON. FRANK A. ROSS.

Jan 12, 1916

By S. C. Termes, R. L. Wilfong

As part of an effort to provide basic data on the fundamental scientific and engineering principles of minerals beneficiation, the Bureau of Mines is conducting research on the flocculation of mineral fines. This paper presents results of studies using cross-linked starches containing carboxyl, diethanolamine, iminodiacetic acid, and xanthate groups to flocculate hematite, goethite, chromite, manganite, pyrolusite, cuprite, and cassiterite fines. The carboxyl and xanthate derivatives flocculated all minerals except cassiterite; the latter was flocculated by only the diethanolamine derivative. The imlnodiacetic acid derivative flocculated hematite, goethite, chromite, cuprite, and pyrolusite fines. Zeta potential measurements were made to help define the reaction mechanism responsible for flocculation. These measurements indicate that electrostatic attraction probably is not involved, except possibly in the case of the diethanolamine derivative. The separation of hematite from quartz by selective flocculation with chelating crosslinked starches under two pH conditions and with two dispersing agents is described. Best recoveries and grades were found when either the carboxyl or xanthate derivatives was added at the natural pH of the pulp in the absence of a dispersing agent.

Jan 1, 1984

By C. A. Siebert, O. S. Duffendack, A. W. Herbenar

IN metallurgical problems involving the study of equilibrium in binary systems, the ,existence of an additional vapor phase, due to the presence of a volatile component in the alloy, has often been neglected. This is well indicated by the modified form of the phase rule, usually accepted in condensed systems in which pressure is not considered as a degree of freedom. In many cases the vapor pressure of the volatile component is exceedingly small and for all purposes can be considered negligible, in which case this form of the phase rule is applicable. However, alloys containing Hg, Cd, Zn, or Mg, tend to show very marked equilibrium vapor pressure, even in the solid state, and therefore present cases where the modified form of the phase rule no longer holds true. A quantitative determination of the vapor pressure of zinc in alpha brasses is not only of practical interest because of the loss of zinc in the processing of these alloys, but also of theoretical interest in that such measurements provide a means of applying the principles of theoretical physics and physical chemistry to problems of applied metallurgy. A number of investigators have reported vapor pressure measurements of zinc in alpha brasses. Hargreaves1 made extensive measurements which were used by Birchenall and Mehl² and Guttman³ for the determination of activity coefficients of zinc in alpha brasses. Hargreaves1 used a differentially heated quartz tube and measured the condensation temperature at one end corresponding to the temperature of the heated brass at the other end. Birchenall and Cheng outlined the condensation method of obtaining vapor pressure of zinc and Cd over some of their silver alloys." The primary object of the present investigation was to increase the range and accuracy of the vapor pressure data for the alpha brasses. Preparation of Alloys: Six alloys were prepared from Bunkerhill zinc and O.F.H.C. copper, both of 99.99 pct purity. The cast ingots were annealed for 24 hr at 550°C, scalped, cold rolled 40 pct and annealed for 50 hr at 550°C. The annealed bars were then surface ground and degasified for 30 min at approximately 550°C in an induction heated vacuum furnace. The surface of the bars was removed before milling the bars into relatively fine chips for chemical analysis and samples for the equilibrium cell. The analyses of the six alloys are given in table I. Experimental Method: The vapor pressure of zinc over the various alloys at a number of temperatures was determined from absorption spectra data. The spark source was produced by means of a high tension discharge between two electrodes of pure zinc. The design of the absorption vessel is shown in fig. 1. The vessel was constructed of transparent quartz which transmits the whole of the visible spectrum and the ultraviolet down to a wave length of 2000 A. The thickness of the vapor space was set at 0.8 mm so as to permit a relatively wide range of measurements without altering the vapor space, and thereby necessitating recalibration of the vessel. The furnace used for heating the absorption vessel consisted of a split wound furnace as shown in fig. 2. The spectrograph used in obtaining the transmitted zinc spectra was a double prism type especially designed for a region of 2500-3500 A. A step diaphragm used in conjunction with a tungsten filament provided the necessary intensity patterns required for calibration of the photographic plates.

Jan 1, 1951

By ANDREW CARNEGIE

Although the noble building provided in New York City by Mr. Carnegie for the United Engineering Society has been pushed to about half-completion, the ceremony of laying its corner-stone was not performed until Tuesday afternoon, May 8, 1906. The stone lies just back of the southeast corner of the building, on the north side-of West 39th Street. Among those present were Mr. and Mrs. Carnegie, Miss Whitfield, the sister of Mrs. Carnegie, Ralph W. Pope, Secretary of the Institute of Electrical Engineers, Frederick R. Hutton, Secretary of the. Society of Mechanical Engineers, Rossiter W. Raymond, Secretary of the Institute of Mining Engineers, Charles H. Haswell, the first Chief Engineer of the United States Navy (1836-1851), now in his ninety-seventh year, John Fritz, of the Bethlehem Steel Company, William H. Fletcher, President of the Engineers' Club, E. E. Olcott, President of United Engineering Society, and other interested friends. After an inspection of the interior of the building, the group formed about the corner-stone, which had been draped with the American flag. The exercises were opened by Mr. Olcott, who appropriately welcomed Mr. Carnegie, and briefly expressed the essential value of the building, saying, in part " The societies to be housed underneath this roof have as their aim the pre¬serving and putting in tangible form of the records of scientific accomplishments so as to avoid the repetition of mistakes. The possibility of finding the records of these results all at one center, so near the great Public Library of our city, will be an inestimable advantage to all professions. It is an occasion of no ordinary moment, therefore, when we can welcome Mr. Carnegie and have him lay for us the corner-stone of this great building which his liberality has provided." Mr. Carnegie responded in happy vein, thanking the committee for their greeting, and expressing his pleasure. in being able to do what he had done to further so worthy a cause. Among other things, he said

May 1, 1906

C. W. GOODALE, Butte, Mont. (member of the committee)- (communication to the Secretary*).-In the discussion of papers presented at the New York meeting of the Institute in February, 1915, and at the Arizona meeting of September, 1916, I referred to the activities of the Bureau of Safety of the Anaconda Copper Mining Co., and I am now submitting a few thoughts by members of the staff of that Bureau. TORGUS H. OAAS, Safety Engineer, Butte, Mont.-The report of the Committee on Safety and Sanitation has described different organizations and methods of promoting safety work. The effectiveness of these methods would aid the beginner in his campaign for safety in choosing the kind of organization and methods best adapted for his field. This can he obtained only by a discussion by those who have long promoted this kind of work, and have met with successful results. As the field is new, the different organizations promoting safety work have not established a common basis of rating for their fatal, serious and slight accidents, so that it is now difficult to get a comparative basis from which to judge the merits of the different systems. C. W. GOODALE.-The U. S. Bureau of Mines adopted, at the beginning, as a basis for its yearly summaries, the number of accidents. per 1,000 men employed, and it is now (quoting from its report for 1915, Technical Paper 168) making the following "classification of injuries:" "Many of the States now have. compensation laws, and in order to conform with their classifications, the bureau's classification of serious and slight injuries for 1915 is on a 14-day (2-week) basis instead of 20 days, as in previous years. The new classification of injuries includes three types, as follows: 1. Fatal 2. Serious (time lost, more than 14 days) (a) Permanent disability Total Partial

Jan 6, 1917

By J. L. Carne

ORE control is a matter of planning and supervision based on a foreknowledge of the content and distribution of ore. The Inspiration orebody is predominately a copper-sulphide blanket, overlain by an oxidized zone of copper silicates, copper carbonates, and barren capping. Most of the ore is treated by leaching, and the optimum requirement of this method is the goal toward which the mining schedule is aimed. Both open-pit operations and underground mining are used. The problems of ore control at Inspiration are: I—maintenance of metallurgical balance, 2—conservation of oxide ore, and 3—mining out of the orebody at an average grade which parallels that of the reserve figure. Prior to the fall of 1926 all of the Inspiration division ores were treated by flotation, but the mixed ores of the Live Oak—Keystone section carried too large a proportion of copper in the form of chrysocolla for satisfactory flotation. For this type of mixed ore the leaching process now in use had been worked out, and the plant was put into operation in the fall of 1926. The process is known as the ferric sulphate leach, and the leaching solvents contain both ferric sulphate and free sulphuric acid. Sulphide copper in the form of chalcocite is leached by the ferric sulphate, and the oxidized copper minerals are dissolved by the sulphuric acid. From the beginning of operations to the present time the plant has treated some 67 thousand tons of ore having an average copper content of 1.142 pct, of which 0.605 pct has been in the form of oxidized copper minerals. The plant is currently being operated at the rate of 11,500 tons per day, 7 days per week. However, this tonnage is produced in 6 days of mine operation. The average current grade is approximately 1 pct copper, of which about 50 pct is present as oxidized or acid-soluble copper. Close control of metallurgical procedures is a vital factor in operation of the plant and is in turn dependent upon careful regulation of feed. An excess of sulphide copper requires the presence of more ferric sulphate in the leaching solvents. On the other hand, an excess of ferric sulphate in the presence of a low sulphide feed seriously reduces the efficiency of electrolytic precipitation in tank house operations. This condition must be avoided at all costs. An additional factor must be considered. It is known that the sulphide content is predominant in the ore which remains in the reserve. To maintain the necessary sulphide-oxide proportion, so that the entire reserve will mine out at both a grade and a sulphide-oxide ratio that will be permissible throughout the remaining life of the property, it is obvious that the oxide reserve must be currently preserved to as great an extent as possible. Fortunately much of the oxide reserve is found in the open-pit operation. This happy circumstance adds flexibility to the procedure and makes it possible to maintain the close regulation necessary to insure best overall results, both mining and metallurgical. The two ore streams from the pit and underground operations join at the coarse-crushing plant, and proper control must be exercised before the ore reaches this point. The open pit is currently providing about 55 pct of the ore and underground operations the balance of production. Both operations are under a single superintendent so that the closely interrelated problems may be more readily controlled. The least flexible of the two producing units is the underground mine, where the mining method is block caving. Although a block of ground may be undercut and developed, characteristics of the material determine its caving action. The ore in the chutes must be drawn. The area currently mined from underground is in a zone predominately sulphide and is generally

Jan 1, 1953

By J. L. Carne

ORE control is a matter of planning and supervision based on a foreknowledge of the content and distribution of ore. The Inspiration orebody is predominately a copper-sulphide blanket, overlain by an oxidized zone of copper silicates, copper carbonates, and barren capping. Most of the ore is treated by leaching, and the optimum requirement of this method is the goal toward which the mining schedule is aimed. Both open-pit operations and underground mining are used. The problems of ore control at Inspiration are: I—maintenance of metallurgical balance, 2—conservation of oxide ore, and 3—mining out of the orebody at an average grade which parallels that of the reserve figure. Prior to the fall of 1926 all of the Inspiration division ores were treated by flotation, but the mixed ores of the Live Oak—Keystone section carried too large a proportion of copper in the form of chrysocolla for satisfactory flotation. For this type of mixed ore the leaching process now in use had been worked out, and the plant was put into operation in the fall of 1926. The process is known as the ferric sulphate leach, and the leaching solvents contain both ferric sulphate and free sulphuric acid. Sulphide copper in the form of chalcocite is leached by the ferric sulphate, and the oxidized copper minerals are dissolved by the sulphuric acid. From the beginning of operations to the present time the plant has treated some 67 thousand tons of ore having an average copper content of 1.142 pct, of which 0.605 pct has been in the form of oxidized copper minerals. The plant is currently being operated at the rate of 11,500 tons per day, 7 days per week. However, this tonnage is produced in 6 days of mine operation. The average current grade is approximately 1 pct copper, of which about 50 pct is present as oxidized or acid-soluble copper. Close control of metallurgical procedures is a vital factor in operation of the plant and is in turn dependent upon careful regulation of feed. An excess of sulphide copper requires the presence of more ferric sulphate in the leaching solvents. On the other hand, an excess of ferric sulphate in the presence of a low sulphide feed seriously reduces the efficiency of electrolytic precipitation in tank house operations. This condition must be avoided at all costs. An additional factor must be considered. It is known that the sulphide content is predominant in the ore which remains in the reserve. To maintain the necessary sulphide-oxide proportion, so that the entire reserve will mine out at both a grade and a sulphide-oxide ratio that will be permissible throughout the remaining life of the property, it is obvious that the oxide reserve must be currently preserved to as great an extent as possible. Fortunately much of the oxide reserve is found in the open-pit operation. This happy circumstance adds flexibility to the procedure and makes it possible to maintain the close regulation necessary to insure best overall results, both mining and metallurgical. The two ore streams from the pit and underground operations join at the coarse-crushing plant, and proper control must be exercised before the ore reaches this point. The open pit is currently providing about 55 pct of the ore and underground operations the balance of production. Both operations are under a single superintendent so that the closely interrelated problems may be more readily controlled. The least flexible of the two producing units is the underground mine, where the mining method is block caving. Although a block of ground may be undercut and developed, characteristics of the material determine its caving action. The ore in the chutes must be drawn. The area currently mined from underground is in a zone predominately sulphide and is generally

Jan 1, 1953

By William Y. Warren

Messrs. Thomas & Cross, having leased from the Akron Cement Company from twelve to fifteen acres of abandoned cement-tunnels and chambers, for the purpose of propagating mushrooms for the market, commenced operations about a year ago, and are now beginning to furnish mushrooms in quantities to the local markets of Buffalo and Rochester. The quarries, or, more properly, the mines, of the Cement Company are located at Akron, Erie County, PIT. Y. The cement-rock occurs in a stratum about 71/2 to 8 feet in thickness, which is overlain by from 1.5 to 25 feet of limestone and flint-rock. There is a gentle rise from the opening of the tunnel inwards, giving a natural drainage and leaving the chambers comparatively dry. The roof is good and is supported by pillars and heavy timbers. The mushroom-beds are located about 300 feet from the opening of the tunnel, and are made in the form of mounds about 3 feet by 12 feet, at the base, and 24 feet high, giving to the chambers the appearance of a subterranean graveyard. Many experiments have been made to determine the best form for the beds, and the mound

Jan 1, 1889

By H. F. Gossenberger, J. J. Tietjen, J. J. Gannon, C. J. Nuese

External quantum efficiency measurements at 300" and 77°K are presented for vapor-grown GaAs and GaAs1-xPx electroluminescent diodes as a function of junction depth and doping. In GaAs, external efficiencies are found to decrease exponentially with increasing junction depth, defining an average absorption coefficient of 900 cm-1 at 300°K and 350 cm-1 at 77°Kfor epitaxial layers of p-type GaAs. It is shown that photon absorption losses dominate at room temperature and, in fact, account for most of the external efficiency degradation between 77° and 300°K. Healever, the internal ('junction) quantum efficiency is also found to decrease by a factor of 3.5 between 77" ALTHOUGH rapid progress has been made in recent years with GaAs, Gap, and their alloys for use in electroluminescent diodes, there are still important unknown factors related to the performance of these de- and 300°K. The dependence of GaAs efficiencies on donor and acceptor concentrations is presented, illustrating best efficiencies at donor concentrations of 1.5 to 2x 1018 cm-3 . External efficiencies are found to be independent of acceptor concentrations less than 3 x 1019 cm-3 but to degrade at higher doping. The fabrication of GaAsi-xPx electroluminescent diodes is briefly discussed. External efficiencies here for planar uncoated diodes are about 0.035 pct at 300°K and 0.4 pct at 77°for x = 0.42. A brightness of about 8500 ft-Lamberts is attained at 77°K and of 315 ft-Lamberts at 300° K. for curvent densities of 10 amp per sq cm. vices. For example, although the external efficiency is known to decrease by factors of typically 10 to 30 between 77°K and room temperature, the exact causes of this are still uncertain. Experimental results of ill' and carr2 with zinc-diffused electroluminescent diodes suggest that this external degradation is almost entirely due to increased absorption losses at room temperature, with a relatively temperature-independent internal efficiency; recent calculations by Gonda et al.3 corroborate this hypothesis. In contrast, Pilkuhn and Rupprecht4 find the internal efficiency of solution-grown GaAs laser diodes to degrade from 100 to 66 to 40 pct as the temperature is increased from

Jan 1, 1969

By J. J. Kramer, W. A. Tiller, G. F. Bolling

The solidification of poly crystalline zone-refined lead has been examined. A novel casting technique was used, with several advantages such as unidirectional heat flow, atmosphere control, and decanting of the liquid during any stage of growth. The experimental results show the separate existence of two textures, a (111) surface texture at the chill surface and a texture in the columnar zone, in the absence of conditions which would produce dendritic growth. WALTON and chalmers have most recently shown that the dendrite direction is the preferred axial orientation for the solidification of many metals in casting. Experimentally, for aluminum and lead, they showed that in the columnar zone the dendrite direction, <l00>, predominated, developing from an equiaxed chill cast layer that exhibited no preferred orientation. A reasonable description of the way in which grains closer to the dendrite orientation were able to encompass other grains was then set forth. For their materials, it was also shown that high superheats could inhibit a preferred axial orientation from developing, presumably by inhibiting dendrite growth. The observations of Rosenberg and iller, on the other hand, showed that zone-refined lead, cast under conditions similar to those of Walton and halmers,&apos; had a definite <111> texture in the columnar zone. However, no examination was made of the chill surface to find out if the columnar zone texture was independent of the orientations at the surface. Since the existence of preferred growth in Upure" lead is thus in doubt, a reexamination of the casting of zone-refined lead is presented here, using a novel casting technique. EXPERIMENTAL PROCEDURES AND RESULTS Zone-refined lead was prepared from two starting materials;99.999+pct supplied by ASARCO, and 99.999pct supplied by COMINCO. The manner of zone-refining and the phenomenological tests for purity after refining, have been describedelsewhere.&apos; The casting apparatus is shown schematically in Fig. 1. The following general procedure was used: The metal was cut directly from the best parts of

Jan 1, 1963

By R. W. Mancantelli, J. R. Woodward

IN 1947 a large low grade deposit of uranium was located in the northwest corner of Saskatchewan, in the Beaverlodge property of Eldorado Mining & Refining Ltd. Most of the values occur as thin seams and as coatings on other minerals, and the ore, which is light and friable, is not amenable to the usual gravity methods of concentration. The acid leaching process developed to retreat the company&apos;s Port Radium tailings was also impractical, as the percentage of carbonates is high and the percentage of sulphides relatively low. Construction of the mill building and installation of equipment, both scheduled for 1952, awaited selection of a satisfactory ore dressing process on or before Oct. 1,1951. An extensive research program on dressing of ores from the Ace mine therefore was undertaken by the Mines Branch in Ottawa, a research team at the University of British Columbia, and an ore dressing group at the company&apos;s Port Hope refinery. Pilot plant operations were conducted at the Ottawa plant of Sherritt Gordon Mines Ltd. under the general direction of C. S. Parsons, consultant on metallurgy and ore dressing for Eldorado. In mid-September, having compared results of the several research programs, Dr. Parsons recommended a process employing a carbonate or basic leach. He reported that, while the chemistry of the process had been proved, engineering of the flowsheet was incomplete, and he suggested that under normal conditions further pilot plant work at the Ace mine might be profitable. However, since this would involve a delay of 12 to 18 months in bringing the property into operation, he recommended that design of the concentrator proceed immediately. Concentrator capacity was determined by two considerations: 1) the amount of ore then available and 2) the expectation that continued improvements would be made in the ore dressing process as a result of the intensive research being carried out by the Mines Branch of the Department of Mines and Technical Surveys. As these improvements could affect both the chemistry and the en-

Jan 1, 1956

By Frederick Laist

I AM APPRECIATIVE of the honor you have done me in electing me to membership in your Society. I value the contacts with men of imagination and ideals which this implies. I am grateful for the recognition of such small contributions as I may have made, or helped to make, to the vast fund of scientific and engineering knowledge. We like to think, as we grow older, that our lives have not been purely parasitical, and that through our efforts some forward step, however small, has been taken toward improving conditions under which we live and do our work. In these days of industrial depression, we hear much criticism of our "machine age." Modern engineering, mass production, the complexity of our lives, all come in for some share of blame. The farmer is said to have been spoiled by the tractor and the gang plow, the factory worker has become a slave of the assembly conveyor, the scientific worker is no longer free but has sacrificed much of his individuality to the research organization of which he is a part. We wonder whether our work as engineers has been worth while and whether our striving after more efficient ways of doing things has been a curse to mankind rather than the boon we thought we were conferring.

Jan 1, 1932

By S. S. Clarke

THE opening of sheet-ground mines in which the ore beds are only from 7 to 9 ft. thick led the Commerce Mining and Royalty Co. to con-sider mechanical loading, in order to avoid the high cost of hand shovel-ing in such mines. Scraper loaders were chosen because the capital investment would be comparatively low; because they are small enough to be used in low working faces, and because they can be mounted on a mobile carrier.

Jan 1, 1939

By S. Arthur Krom

(Wilkes-Barre meeting, June, 1911.) RECENT experiments indicate that the usual type of concentrating-table is not only poorly adapted to produce the desired results, but also is based upon an incorrect principle, namely, the use of riffles to perform the work of stratifying the various minerals. We have heard a good deal about riffles for concentrating-tables; exhaustive experiments have been made to discover the proper form of riffle, or to prove the superiority this or that form; disputes and patent-litigation have arisen over the matter of riffles, and thus many have been led to believe that the riffle is the saving-device upon which the process of concentration depends. In the present paper it is proposed to show that the riffle is greatly overrated as to the part it performs in the concentration of minerals, and that, in the near future, it may possibly be eliminated entirely from that process. The experiments in question have shown that the troublesome riffle can be considered of secondary importance at the most, and should be so classed in the construction of a concentrating-table built upon the right lines. The action of any form of riffle on a concentrating-table is such as to upset and retard the process of settling and stratifying the various minerals on the table-deck. From the deck of a riffled table no concentrates can be delivered until the deck is "bedded," that is, until a sufficient amount of metallic values have been fed to the table to spread over a large portion of the deck, forming a substratum of the heavier minerals. This substratum must be maintained by the feed within quite narrow limits, and directly proportional to the rate of discharge from the table, in order that the bed shall not be lost. On the other hand, the riffles having a very lim-

Jul 1, 1911

By G. W. Mao, A. M. Gaudin, D. W. Fuerstenau

Jan 1, 1960