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"Located on Missouri River 16 miles N. E. from Helena, 67 miles from Butte and 18 miles below Canyon Ferry. River drainage area 16,000 sq. miles.DAM: Built in 1907; rebuilt of concrete in 1911. Maximum height 129.3 ft., length over all 720 ft.; elevation of crest 3621; elevation of bridge 3640; normal head 60'; normal tail water elevation 3568.5.SPILLWAY: Length over all 491 ft.; clear opening in 24 sections; 445' flashboards, 14 high to elevation 3635, which is 3.5' above Canyon Ferry normal tail . water elevation.PENSTOCKS: 5 of steel, 12 ft. diam., about 75 ft. long from canal to main turbines, and 3 40-inch diam. from canal to exciters.WHEELS: 5 main pairs, horizontal, center discharge, 48-inch bronze turbines, 225 rev., 4,000 h-p. at 60 ft. head, made by S. Morgan Smith Co., direct coupled to generators, and--3 single, horizontal, 25-inch units, direct coupled to exciters.GENERATORS: 5 W. E. & M. Co. water wheel type, revolving field, 2,800 k-w., 2,400 v., 225 r. p. m., 3 phase, 60 cycle alternators.OPERATION: The plant has a larger water storage than Canyon Ferry and can also use stored water from Canyon Ferry storage. Separate transmission lines 13 miles long connect to lines from Canyon Ferry to Butte, and the Plant operates in parallel with the Canyon Ferry plant."

Jan 1, 1913

By F. R. Hensel

PuRe silver and silver-lead alloys have been studied as to their suitability for bearing~.' A review of the properties of thallium and the silver-thallium constitutional diagram was made by the author to analyze the possibilities of silver-thallium compositions for antifriction materia1s. t The silver-rich end of the diagram as reported in the literatureg-" was found to be sketchy and it was necessary to carry out corisiderable experimental work to arrive at definite conclusions. Some of the results of this work are reported in this paper. Test Materials In the beginning of the work, only fused alloys were investigated. Later, research Table i.—Composition of Fused Silver-thallium Alloys Tested for Antifriction Properties Percentage Alloy No. of Thallium 1533...................... 0.48 1534.................... 1.06 a31 HT................... 2.04 231....................... 2.10 232 HT................... 3.83 Balance 232....................... 4.07 Silver 233 HT................... 5.86 a33....................... 6.38 a34....................... 9.84 a34 HT................... 10.07 was carried out on electroplating methods and diffusion processes. In preparing the fused alloyst care was taken to exhaust the toxic fumes caused by the thaillium content. The compositions of the series of fused alloys are listed in Table I. The silver-thallium alloys were melted in clay-graphite crucibles and cast into preheated steel molds of 3/4-in, diameter. In the cast condition, they showed a cored structure, as indicated by the micrographs of Figs. I to 3. The etching reagent used was a mixture of 2 grams K2Cr207, 8 C.C. H2S04, and IOO C.C. H20. The cored structure is unsatisfactory for the type of corrosion resistance required for bearing applications, and homogenizing experiments were carried out at various temperatures, the results of which are shown in Figs. 4 through 8. The alloys with a lower thallium concentration, which were heated for 2 hr. at 525°C show an almost completely homogenized solid solution type of structure. With higher thallium concentration, the homogenizing temperature was dropped to 475OC. to eliminate the formation of a liquid phase. It is evident that heating for 2 hr. at this temperature did not iesiilt iii complete elimination of the cored structure. As would be expected, cold-working of the cast structure is an expedient in establishing equilibrium conditions. The fine homogeneous grain structure shown in Fig. 7 corresponds to the cold-worked area under the Rockwell ball penetration when the hardness was taken before heat-treatment. A detailed structural study was made on a cast silver-thallium alloy containing 3.67 per cent thallium. Three micrographs (Figs. 9, 10 and 11) show the transition

Jan 1, 1946

By F. R. Hensel

PuRe silver and silver-lead alloys have been studied as to their suitability for bearing~.' A review of the properties of thallium and the silver-thallium constitutional diagram was made by the author to analyze the possibilities of silver-thallium compositions for antifriction materia1s. t The silver-rich end of the diagram as reported in the literatureg-" was found to be sketchy and it was necessary to carry out corisiderable experimental work to arrive at definite conclusions. Some of the results of this work are reported in this paper. Test Materials In the beginning of the work, only fused alloys were investigated. Later, research Table i.—Composition of Fused Silver-thallium Alloys Tested for Antifriction Properties Percentage Alloy No. of Thallium 1533...................... 0.48 1534.................... 1.06 a31 HT................... 2.04 231....................... 2.10 232 HT................... 3.83 Balance 232....................... 4.07 Silver 233 HT................... 5.86 a33....................... 6.38 a34....................... 9.84 a34 HT................... 10.07 was carried out on electroplating methods and diffusion processes. In preparing the fused alloyst care was taken to exhaust the toxic fumes caused by the thaillium content. The compositions of the series of fused alloys are listed in Table I. The silver-thallium alloys were melted in clay-graphite crucibles and cast into preheated steel molds of 3/4-in, diameter. In the cast condition, they showed a cored structure, as indicated by the micrographs of Figs. I to 3. The etching reagent used was a mixture of 2 grams K2Cr207, 8 C.C. H2S04, and IOO C.C. H20. The cored structure is unsatisfactory for the type of corrosion resistance required for bearing applications, and homogenizing experiments were carried out at various temperatures, the results of which are shown in Figs. 4 through 8. The alloys with a lower thallium concentration, which were heated for 2 hr. at 525°C show an almost completely homogenized solid solution type of structure. With higher thallium concentration, the homogenizing temperature was dropped to 475OC. to eliminate the formation of a liquid phase. It is evident that heating for 2 hr. at this temperature did not iesiilt iii complete elimination of the cored structure. As would be expected, cold-working of the cast structure is an expedient in establishing equilibrium conditions. The fine homogeneous grain structure shown in Fig. 7 corresponds to the cold-worked area under the Rockwell ball penetration when the hardness was taken before heat-treatment. A detailed structural study was made on a cast silver-thallium alloy containing 3.67 per cent thallium. Three micrographs (Figs. 9, 10 and 11) show the transition

Jan 1, 1946

By Joseph A. Whitchurch

The N20 to N25 Tunnel (basic) segment was the second tunnel contract awarded for construction by The PB/MK Team. This project embodied 3.9 km (2.4 miles) of tunnel and was located within the northwest quadrant of the 86.9 km (54 mile) long main collider ring. The contract required the excavation and initial support of a 54.3 m (178 vlf) deep ventilation shaft, a connecting horseshoe shaped Adit and TBM starter tunnel and 3,865 m (12,680 If) long main collider tunnel with a 4.3 m (14 ft) minimum finished diameter. This paper discusses the construction methods, equipment utilized and the production achieved in the construction of the ventilation shaft, connecting adits and the main collider tunnel.

Jan 1, 1995

Aalde, Kaare. ('40) Gen'I Del., Bisbee. Ariz. Aase, Glenn D., ('40) Univ. of North Dakota. Grand Forks. N. D. Abadesco, Enrique A., ('39) College of Engrg.. Univ. of the Philippines. Manila, P. I. Abbott. John L., ('40) Colorado School of Mines. Golden. Colo. Abdul-Ahad, A., ('39) Montana School of Mines. Residence Hall, Butte. Mont. Abreu, Ovidio M., ('38) Univ. of Nevada, Reno, Nev. Acomb, Allen. ('41) Louisiana State Univ., Box 1970, University. La. Acosta S., Gonzalo. ('40) Univ. of Texas, Univ. Sta., Box 1785. Austin, Tex. Adam, Howard W., ('41) Montana School of Mines. Butte, Mont. Adams, Albert, ('381 New Mexico School of Mines, Socorro. N. M. Adams. Charles W., ('39) Michigan College of Min. & Tech., Houghton, Mich. Adams. H. Travis, ('39) 316 South -5th St., Bur¬bank. Calif. Adams, Jack L., ('39) Univ. of Oklahoma, Nor¬man. Okla. Adams. John W., ('41) Colorado School of Mines, Golden. Colo. Adams. Lewis J.. ('39) 402 Del Mar Blvd., Corpus Christi, Tex. Adams, Rob L., ('40) Agricultural & Mech. Col¬ lege of Texas. Box 600, College Sta., Tex. Adamson. Charles R., ('41) Univ. of Utah, Salt Lake City. Utah.

Jan 1, 1941

By B Beamish

The concept of a ‘critical velocity zone’ in the longwall goaf environment for the development of a spontaneous combustion event has been supported by numerical modelling. However, there is no experimental data available for Australian coals to show ventilation effects on the self-heating incubation behaviour of broken coal in the longwall goaf. A preliminary study using incubation testing has been completed on three high volatile bituminous coals (A, B and C) with R70 self-heating rate values of 3.86°C/h, 3.15°C/h and 2.09°C/h and moisture contents of 11.3 per cent, 3.9 per cent and 4.7 per cent, respectively. Mass to flow rates used in the adiabatic oven reaction vessel have been selected to be indicative of a sluggish, natural air leakage and medium ventilation environment. Under a sluggish ventilation flow rate all three coals incubate to thermal runaway in minimum time frames of 2.8–3.1 years, 34–42 days and 79–95 days, respectively. When the ventilation flow rate is increased to natural air leakage, coal A with the highest R70 value and highest moisture content selfheats to 28°C above mine ambient temperature before heat loss takes over due to moisture evaporation. However, both Coals B and C at this flow rate incubate to thermal runaway in a shorter time frame than under sluggish flow. At the medium ventilation flow rate, only Coal B incubates to thermal runaway, albeit after a significant extended period of time. These results show how important it is to determine the heat balance between the coal intrinsic reactivity (as indicated by the R70 value) and moisture content. The results also have implications for the possible location of the ‘critical velocity zone’ and subsequent hotspot development and migration.

Oct 12, 2022

By W. J. Schlitt, K. McNaughton

A heap-leach field test was conducted during the 1993-1994 winter season at Carmacks, Yukon Territory, Canada. The purpose of the test was to demonstrate the viability of heap leaching Carmacks oxide copper ore in an arctic setting on a year-round basis. The test itself utilized a 5-m-diam crib loaded with 250 t of composite ore from the Carmacks copper deposit. The ore was stacked to a total height of 7 m in the crib, including 1 m of ore as an over- layer above the emitter system. This matched the plan for the commercial heap at the time when the test was started. The design also replicated an interior segment of the commercial heap. Leaching was done at a flow rate of 0.2 L/min/m2 using leachate at 21 °C. This temperature was maintained with no external heat input other than normal process heat transferred from electrowinning to the leachate via solvent extraction. Winter conditions were quite typical of those expected at the mine site. The temperature reached -54°C, while averaging -13°C over a three-month period. In spite of some flow system problems, leaching continued unabated, and freezing was limited to the insulating ore over-layer and isolated points near the outer crib walls. Thus, the test demonstrated that year-round heap leaching of Carmacks copper ore is practical in an arctic setting.

Jan 1, 2000

By AIME AIME

Council.* PRESIDENT OF THE COUNCIL. JOHN HAYS HAMMOND NEW YORK, N. Y. (Term expires February, 1908.) VICE-PRESIDENTS OF THE COUNCIL. HENRY M. HOWE NEW YORK, N. Y. J. B. GRANT DENVER, COLO. JAMES D. HAGUE NEW YORK, N. Y. (Term expires February, 1908.) SAMUEL B. CHRISTY BERKELEY, CAL. JOHN A. CHURCH NEW YORK; N. Y. New PERSIFOR FRAZER PHILADELPHIA, PA. (Term expires February, 1909.)

Mar 1, 1907

Jan 1, 1897

PRESIDENT AND DIRECTOR EUGENE MCAULIFFE OMAHA, NEBR. PAST PRESIDENTS AND DIRECTORS HERBERT G. MOULTON NEW YORK, N. Y. JOHN R. SUMAN HOUSTON, TEXAS TREASURER AND DIRECTOR H. T. HAMILTON NEW YORK, N. Y. VICE PRESIDENTS AND DIRECTORS ERLE V. DAVELER NEW YORK, N. Y. W. M. PEIRCE PALMERTON, PA. PAUL D. MERICA NEW YORK. N. Y. LEROY SALSICH DULUTH, MINN. CHESTER A. FULTON NEW YORK, N. Y. L. E. YOUNG PITTSBURGH, PA.

Jan 1, 1942

By Mario Aiezza

This paper outlines the results of a relationship developed during the design and construction of the foundations for the Gallery Towers project in Melbourne. Both the builder and the piling contractor were determined to arrive at a satisfactory foundation solution to the problems encountered at the site. The scope of piling work was to provide load-bearing piles under the building columns, some of which were located within a retention system that also required a piling solution. Geological conditions were variable and challenging. The site area was small and located adjacent to the National Arts Centre in the developed Southbank area, a high density office area. This presented logistical problems in limiting construction traffic on site and also demanding minimal noise and vibration emanating from piling activities. The piling contractor, Vibro-Pile, and the builder, Walter Construction Group, faced the challenges presented with a refreshing cooperative attitude that was beneficial to both companies. Commercial issues rising from design and construction problems were first put apart in order to allow the respective technical department of each company to work with minimum constraints to achieve the most cost effective solution. In the process usual adversarial attitudes resulting in loss of time and money was avoided. A number of issues were addressed successfully at minimum cost and time during this contract. Despite the difficulties encountered, the job was completed on time and with negligible claims for extras, resulting in the development of a strong mutual respect between both companies.

Jan 1, 2002

By Henry R. Linden

The demand for natural gas continues to increase at higher than anticipated rates, partly because of its widening price advantage over most other fossil fuels when the cost of air pollution control is included. However, there are clear indications that natural gas supply from the contiguous 48 states and continental shelves will not indefinitely keep up with this rapid growth in demand. Projections are presented which define the extent of potential deficiencies from the 1970's to the year 2000. Among the sources of supplemental gas - imported pipeline natural gas from Canada and Mexico, tanker import of liquefied natural gas, and synthetic pipeline gas from coal and oil shale - by far the most abundant at potentially competitive costs is pipeline gas from coal. The state of development and relative economics of the various coal gasification processes are reviewed. It is shown that synthetic pipeline gas could become a very substantial market for bituminous coal and lignite at current minemouth prices - 60-70 million' tons of coal for each trillion cubic feet of synthetic pipeline gas produced. This corresponds to only slightly more than the current annual increase is gas demand.

Jan 1, 1969

By H. W. Schadler

The superplastic behavior of low carbon and manganese bearing steels has been evaluated. The results of elevated-temperature stress-strain rate and elongation tests are reported which indicate that high strain rate sensitivity (>0.5) and adequate elongations are achievable in ultrafine-grained steels 1 to 2 p, but at strain rates which are not commercially attractive. It has been demonstrated that the fine grain size is retained after long times and high strains if the temperature is kept within the range of the two-phase (a + ?) field. INTEREST in superplasticity has been stimulated by the desire to: 1) understand the origin of, and mechanisms responsible for, the large uniform elongations observed, and 2) exploit this property for commercial advantage in metal forming operations. Although the Zn-22 wt pct Al alloy presently being studied as a model material1-5 may find application in sheet forming and extrusion, the potential of super-plasticity should best be realized in large tonnage materials, such as steel and aluminum alloys. The degree of superplasticity in low-carbon and manganese-bearing steels has been evaluated. The results of elevated-temperature stress-strain rate and elongation tests on ultrafine grain size material are reported. Avery and Backofen6 and Hart7 have shown that geometrically stable flow leading to extensive uniform elongation in the tension test is associated with high values of the strain rate sensitivity, m, defined: Lozinsky had reported that titanium and zirconium experience permanent deformation if subjected to a constant load and cyclic heating through the temperature range of the phase transformation. Although strain rate sensitivities in excess of about 0.2 had not been reported previously for steel, permanent deformation had been observed11-13 in a wide variety of steels subjected to a constant load and cyclic heating through the temperature range of the a-? phase transformation. Thus by analogy, steel could be expected to exhibit high strain rate sensitivity but only in the a + ? condition. High strain rate sensitivity has been observed at 650°C (a + Fe3C), but not reported as such, by Bailey, Dickenson, and pearson14 in 1931 at a strain rate of about 10-9 per min. It then remained to determine whether high tensile elongations would be observed in a rate-controlled test at constant temperature and at what strain rate strain rate sensitivity values greater than 0.5 would be observed. Since previous experience8 had indicated the importance of fine grain size to realizing high m at reasonable strain rates, it was first necessary to produce an ultrafine grain size and then keep the grains from growing during the test. The results of this investigation show that fine grain size can be readily produced16 and maintained by restricting the temperature of testing to below the ? transus. Further, superplasticity (high m and large uniform elongation) is observed. However, the strain rate range is only marginally useful for commercial forming operations with the finest grain size produced. MATERIAL The material investigated initially was a 1.9 wt pct Mn, 0.42 wt pct C, hot-rolled bar previously used by Low and Turka1015 and available in the laboratory. The 0.500-in. round was cold-rolled to a 0.090-in. flat, annealed for 4 hr at 850°C in argon, air-cooled, and cold-finished to 0.050 in. Subsequently, four additional steels of the compositions given in Table I were investigated to explore the effects of manganese, carbon, and test temperature on the observed stress-strain rate behavior. These steels were melted under argon, cast to 0.75 by 2 by 5 in. slabs, hot-rolled at 850°C, surface-finished to 0.13 in., and cold-finished to 0.050 in. Sheet tensile specimens 0.200 in. x thickness with 1- or 2-in. gage length were cut parallel to the rolling direction. Table I also includes the nominal transformation temperatures for the AISI 1340 and the four experimental steels. EXPERIMENTAL PROCEDURE Production of Fine Grain Size. Ultrafine grain size (1 to 5 p) was considered essential for this studv. Grange16 has described two techniques for producing

Jan 1, 1969

ALABAMA Aldrich.-Lloyd, T. W. Anniston.-Carrington, F. G. Klugh, B. G. Bessemer.-Abbott, C. E. Dobbs, G. G. Ferguson V. Salmon, h. S. Stuart, Q. W. Birmingham.-Adams, J. H. Aldrich, T. H. Aldrich, T. H., Jr. Allen, A. W. Armstrong. W. D. Ball, E. M. Bonnyman, J. Bush, M. W. Carter, E. Crawford, G. G. Davis, C. B. Dryer. T. B.

Jan 1, 1923

Council PRESIDENT OF THE COUNCIL. JOHN HAYS HAMMOND NEW YORK, N. Y. (Term expires February, 1908 ) VICE-PRESIDENTS OF THE COUNCIL. HENRY M. HOWE NEW YORK, N. Y. J. B. GRANT DENVER, COLO. JAMES D. HAGUE NEW YORK, N. Y. (Term expires February, 1908.) SAMUEL B. CHRISTY BERKELEY, CAL. JOHN A. CHURCH NEW YORK, N. Y. PERSIFOR FRAZER PHILADELPHIA, PA. (Term expires February, 1909 )

Jan 1, 1910

THE Institute of Metals Division of the A. I. M. E. has joined with the American Society for Steel Treating and the American Welding Society in support of National Metal Week in Philadelphia, Oct. 8 to 12. Individual and joint technical sessions, plant inspection trips, and a general exposition to be held in Commercial Museum have all been arranged. With the coming of the Institute of Metals Division into the circle, the scope of the exposition has been broadened to cover non-ferrous metals, and exhibits of much interest are promised. Headquarters for the Institute of Metals and the American Society for Steel Treating will be at the Benjamin Franklin Hotel, and for the American Welding Society at the Bellevue-Stratford. The American Society for Steel Treating and the Welding Society will hold technical sessions each forenoon at their hotel headquarters. The Institute of Metals Division will hold sessions Tuesday morning and Wednesday and Thursday afternoons; that for Wednesday being a joint session with the American Society for Steel Treating. The latter society will hold independent afternoon sessions on Thursday and Friday. Registration and information desks will be open at the hotels throughout the week, and an attractive program of entertainments has been arranged.

Jan 1, 1928

By H. C. Gatos, J. T. A. Pollock

It is well known that the superconducting critical current densities of many alloy superconductors may be increased by cold working and in some cases further enhanced by a short heat treatment. This latter enhancement has been attributed to the redistribution of dislocations into cell-like networks' and to the precipitation of second phase particles,2'3 which act as flux pinning centers. In a manner analogous to dislocation pinning in precipitation hardening alloys,4 it is expected that here also a critical distribution of the pinning centers should result in maximum pinning effect. Concentration inhomogeneities exist in most or all commercial alloys yet there have been only a few attempts made to determine their effect on critical current capacity in the absence of cold working. Sutton and Baker,5 and Kramer and Rhodes6 have found that the complex precipitation processes occurring during the aging of Ti-Nb alloys can result in critical current density enhancement. Livingston7-10 has clearly shown, for lead and indium based alloys, that the distribution of precipitated second phase particles is of critical importance in determining magnetization characteristics. However, these '(soft" alloys age at room temperature and the time involved in specimen preparation prevents metallographic examination in the state in which the superconducting measurements are made. Thus results with such alloys are expected to be biased towards larger precipitates and interpar-ticle spacing. The present study of Ta-Zr alloys was undertaken to examine the influence of second phase precipitation, as controlled by heat treatment, on the critical current capacity of well annealed polycrystalline material. A study of the published phase diagram11 indicated that annealing supersaturated samples containing up to 9 at. pct Zr at suitable temperatures would result in the precipitation of a zirconium-rich second phase. It was MATERIALS AND PROCEDURE The alloys were prepared from spectrochemically pure tantalum and zirconium. Analysis was carried out by the supplier. Major impurities in the tantalum were: 12 pprn of 02, 17 pprn of N2, 19 pprn of C, and less than 10 ppm each of Mo, Nb, Al, Cr, Ni, Si, Ti. The crystal bar zirconium was pure except for the following concentrations: 15 pprn of 02, 17 ppm of C, 23 ppm of Fe, 11 ppm of Cu, and less than 10 pprn each of Al, Ca, N2, Ti, and Sn. Samples were prepared in the form of 8 to 10 g but-tons by arc melting using a nonconsumable electrode on a water-cooled copper hearth in a high purity ar-gon atmosphere. Each button was inverted and re-melted three times to ensure an even distribution of the component elements. The samples were then homogenized at temperatures close to their melting points for 3 days in a vacuum furnace maintained at 5 x 10-7 mm Hg. After this treatment the buttons were cold rolled to sheets approximately 0.020 in. thick from which specimens were cut, 0.040 in, wide and 1 in. long suitable for critical current density (J,) and critical temperature (T,) measurements. These strips were then recrystallized and further grain growth was allowed by an additional vacuum heat treatment at 1800°C for 60 hr. Some second phase precipitation occurred during cooling of the furnace and a solution treatment was necessary to produce single phase supersaturated samples. This treatment was successfully carried out by sealing the samples together with some zirconium chips in quartz tubes under a vacuum of 5 x 10-7 mm Hg, heating at 1000°C for 5 hr and then quenching into water or liquid nitrogen. The samples were then heat treated at either 350" or 550°C and quenched into water or liquid nitrogen. All samples which were heat treated at 350°C were quenched in both cases by cracking the capsules in liquid nitrogen. The samples treated at 550°C were quenched by dropping the capsules into water. Analysis for oxygen in randomly selected samples indicated that the oxygen content was in the range of 175 to 225 ppm. Values of Tc were determined by employing a self-inductance technique. Jc measurements were made at 4.2oK by increasing the direct current through the wire in a perpendicularly applied field until a voltage of 1 pv was detected with a null meter. The risk of resistive heating at the soldered joints during these latter measurements was reduced by first plating the ends of the wires with indium and then soldering to the copper current leads using tin. Metallographic examinations were performed after mechanical polishing of the same samples and etching in a 4H20:3HN03 (conc):lHF(conc) solution.

Jan 1, 1970

By Lawrence Addicks

(San Francisco Meeting, September, 1915) THROUGH the courtesy of Dr. James Douglas I am permitted to give, a summary of some of the results obtained in leaching slimes tailings in a series of experiments conducted under my direction at Douglas, Ariz.. during the past year. While the test run for which the data are given deals with a particular case, much of the work is general in its application and may therefore be of interest. This work was done upon the ores of the Burro Mountain Copper Co. A description of the geology of the district will be-found in the paper by R. E. Somers published in the May, 1915, Bulletin of the Institute. The mineral is pyrite and chalcocite very finely disseminated throughout the gangue and a characteristic of all the ores is the large amount of alumina present. A representative analysis of the particular ore under consideration would be about as follows: Cu, per cent 2.35 S, percent 3.0 Ag, ounces per ton 0.05 CaO, per cent 0.5 Au None K202, per cent 4.0 Fe, per cent 1.5 SiO2, per cent 70.0 A120,, per cent 13.0 The leaching of the ore direct was early dismissed from consideration for the following reasons: 1. The ore would have to be quite finely crushed to liberate the mineral for leaching; concentrating after crushing would cost but a few cents a ton; and a higher total recovery would result from leaching tailings rather than ore. 2. Rough concentration would yield a suitable material for roasting to make sulphur dioxide or sulphuric acid in connection with the leaching scheme. 3. Such a program put the question of cost vs. recovery on a basis where flotation and discarding of tailings were directly comparable.

Jan 8, 1915

Jan 1, 1966

By William P. Shinn

Jan 1, 1881