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By M. B. Bever, A. K. Jena

THE heats of formation ?H at 273°K of the compound AgMg as a function of composition have been measured by solution calorimetry.1 The value at the stoichiometric composition is -4.41 kcal per g-atom. From electromotive force measurements2'3 the heat of formation at 773°K of stoichiometric AgMg has been determined as -5.19 kcal per g-atom.4 The combination of these two values results in an unusually high negative temperature coefficient of the heat of formation d?H/dT = ?Cp = -1.6 cal per g-atom-OK. By contrast, published heat contents of the compound AgMg and the component elements above room temperature5 indicate that the temperature coefficient of the heat of formation of AgMg is nearly zero. In this communication calorimetrically measured heats of formation of A.K.JENA,Junior- MemberAIME,andM.B. BEVER,Member AIME, are Staff Member, Division of Sponsored Research, and Professor of Metallurgy, respectively, Massachusetts Institute of Technology, Cambridge, Mass. Manuscript submitted July 1, 1968. IMD AgMg below room temperature are reported and the temperature dependence of the heat of formation is discussed. The heat effects of additions of samples of the compound AgMg containing 50.1 at. pct Mg to liquid tin-rich solutions at 623°K were measured in a solution Calorimeter.6 The heat effects of additions plotted against the average of the atom fractions of solutes in the solution before and after each addition were a linear function of composition from which the heat effect at infinite dilution was obtained, Table I. The calorimeter was calibrated by additions of tin; the heat content (H623°K - H273°K) of tin was taken as 4.08 kcal per g-atom.4 The heat effect at infinite dilution of an addition of where heat of formation of AgMg at T°K, T = temperature from which samples are added (78°, 195°. and 273°K), Xi = atom fraction of i in AgMg, ?Hi = relative partial gram-atomic enthalpy of i in tin-rich solution.

Jan 1, 1969

C. A. ROSE, New York, N. Y. (written discussion *).-Without doubt the excellent results obtained at Ajo will cause surprise among metallurgists; 75 per cent. average capacity and 80 per cent. extraction during the first year of operation of a plant using a new metallurgical process are figures that speak for themselves. It is obvious that the most troublesome feature of the process is the fouling of solutions. The effects of this are most evident in the electrolytic tank house; but apparently the solutions are so heavily loaded with salts that their dissolving power is also impaired. This is indicated by the fact that copper comes into solution during washing after the leaching of the ore is completed, as shown by the decreasing ratio of acid to copper in the various washes tabulated in Table 4, and also by the fact that 4.9 per cent. of the total copper in the ore remains in the tailings in a soluble form. Even though the extraction in leaching and the ampere efficiency in electrolysis would be benefited by keeping the salts in solution at a lower concentration, it is doubtful whether it would pay to decrease these salts by discarding more electrolyte without other changes in the, process, since this would increase the amount of cement copper produced, which is already very large. If, however, it would not disturb the process otherwise, this object could be accomplished by increasing the range of electrolysis, so that solution going to the tank house would contain, say, 4 per cent. copper and 1 per cent. acid, and the solution returned to the leaching plant 1 1/2 per cent. copper and 4.8 per cent. acid, and by increasing the volume of solution to be discarded, this to be taken from the electrolyzed solution returned to the leaching plant. By this arrangement, more salts will be removed from the system per ton of cement copper produced; and if sufficient solution is discarded to keep the iron content down to 1 1/2 per cent. it would he feasible to recover the copper from

Jan 4, 1919

By AIME AIME

THE session* on Non-ferrous Metallurgy held Monday morning was conducted in a most satisfactory manner with F. F. Colcord, vice-president, U. S. Smelting Co., in the chair. In spite of the early hour and the fact that members desired to register first, the meeting started quite promptly, with almost every chair in the room occupied. About 65 men were present and during the morning many more came but, not being able to find room, drifted away to other fields of activity. The first paper presented, "Lead Refining Practice of the Bunker Hill Smelter of the Bunker Hill & Sullivan Mining & Concentrating Co.," by Alfred F. Beasley (T. P. 303), was read in abstract by Edward H. Robie, and an animated discussion followed in which Messrs. Johnson (written discussion), Brewer and Jones and Professor Hayward participated. The discussion hinged principally on the liquation of the zinc crusts, but Professor Hayward called attention to the fact that the practice of keeping the gold and silver crusts separate was not new and the present scheme illustrated the axiom that processes based on fundamental principles should not be considered as extinct; one can never tell when it may be found advantageous to make use of them again.

Jan 1, 1930

By D. C. Shelton

Eq. 4 and 5 on page 5 of the March 1965 issue of Transactions, and Eq. 12 on page 8 of the same issue should read respectively:

Jan 1, 1965

By J. C. Fisher

THE following facts are reasonably well established concerning the influence of boron on the hardenability of steel:1-4 1—Boron does not appreciably influence the ther-

Jan 1, 1955

By Strathmore R. B. Cooke, Paul B. Queneau

The kinetics of the dissolution of scheelite in basic solutions of carbonate and fluoride were investigated. Work was also done with solutions of alkali metal chloride, hydroxide, phosphate, and mixtures of phosphate and fluoride. The study was conducted at 90 psig and at temperatures ranging from 100" to 155"C, and both natural and synthetic scheelite single crystals were used. The interaction of scheelite with carbonate solutions generally followed a parabolic rate law, and resulted in the formation of calcite crystals on the attached surface. The transport of the CO3 through the calcite to the scheelite surface was probably rate -controlling between 115" and 135°C. Positive deviations from Parabolic behavior were observed at 100" and 155?C, presumably due to the calcite grain growth, and to the formation of a noncoherent calcite layer, respectively. The leaching of scheelite with alkaline fluoride solution produced a calcium fluoride reaction-product which covered the surface as a sheet-like layer. Below 110°C the dissolution rate was parabolic; at 115" and 135°C it was linear. In the linear region, the periphery of the calcium fluoride layer lifted from the sample. Only the lower layers, braced by the scheelite substratum, remained unbroken. This bound layer, approximately constant in thickness, limited the rate at which the fluoride could attack the scheelite. The phosphate and phosphate-fluoride leaches dissolved scheelite at a linear rate; solid reaction products were respectively hydroxyapatite and fluorapatite. Sodium hydroxide and chloride were not effective leachants, and did not produce observable solid reaction products. THE feasibility of pressure leaching of scheelite pulps with basic solutions containing either carbonate or fluoride ions, as indicated by the following equations, has been established by previous investigators:1-3 200°C CaWO4s + CO37q - CaCO3s+WO4aq [1] 200°C CaWO4s + 2Faq ^ CaF2s+WO4aq [2] It is to be noted that a commercial process employing reaction [I] is in use at Union Carbide's operation near Bishop, Calif. In the earlier work referred to, it was apparent that the precipitation of the solid reaction-product on the scheelite particles sharply reduced contact of the leachant with the scheelite. We have extended this work by studying the kinetics of dissolution employing single crystals of scheelite of known exposed surface area. In addition, the effectiveness of solutions of phosphate, of phosphate with fluoride, and of chloride and hydroxide as leachants for scheelite have been investigated. EXPERIMENTAL Apparatus. The low-pressure autoclave used in this wo (100 psig maximum) is essentially that of J. Halpern4 as modified by F. A. Forward.5 Constructed entirely of 316 stainless steel, its maximum capacity is 4000 ml. The temperature in the autoclave was regulated to *0.5?C by a Wheelco thermocouple controller. A 4-in. diam, three-bladed impeller, circulated solution upward against the sample, and a strobo-scope permitted holding the stirring rate to *15 rpm. A check valve and a "pop" type safety valve were installed, a sample holder was fixed to an externally adjustable rod, and a water-cooled condenser was placed in series with the sampling valve. The stainless steel sample holder, Fig. 1, held the epoxy-mounted sample (f) five mm above the impeller. Tightening the tapered sleeve (d) positioned the epoxy-resin specimen-mount by forcing it back against the spacer (c). The mount (e) was 1 in. diam. Sample Description and Preparation. Both synthetic and natural scheelite crystals were leached. The former were single crystals of 99.95 pct purity which were leached approximately perpendicular to the "c" axis; they were supplied by the Gallard-Schlesinger Chemical Manufacturing Corp. The natural crystals, supplied by Minerals Unlimited, were transparent, analyzed 99.8 pct CaWO4, and in ultraviolet illumination exhibited the characteristic blue glow of substantially molybdenum-free scheelite. To permit exposure of an essentially constant surface area of scheelite to the leachant, the samples were mounted in Scotchcast Brand Resin No. 250 (Minnesota Mining and Manufacturing Co.). The mount-

Jan 1, 1970

By John Henry Harden

This shaft, located in the northern anthracite coal-field about 2300 feet southwest from the court-house at Wilkes-Barre, in the County of Luzerne, Pa., is the property of the Lehigh & WilkesBarre Coal Company. The sinking and cribbing to the solid rock (see isometrical view on Plate IX) was conducted by Mr. W. W. Kenrick. Dimensions of the earthwork to the foundation of the cribbing, 51' 2" long, 17' 4" wide, 31' deep. Total amount of excavation in cubic yards, 998.5. Dimensions within the permanent cribbing, 45' 4" long, 11' 16" wide, 31' deep, divided into six parts by buttons 8" x 12", each division, 7' x 11' 6". Permanent cribbing 12" x 12"; temporary cribbing 8" x 10" ; backing, 3" thick ; clay puddle to exclude surface water, 12" thick; conductors, 8" x 5"; lining, 1" thick from top to bottom of the shaft. In the latter part of the year 1871, Mr. H. Murray & Son contracted with the company for the continuation of the work at the rate of four hundred dollars per yard in depth, to a point 100 feet below the Hillman seam of coal; for the succeeding 100 feet the price to be increased twenty-five dollars per yard, and so on until the bottom rock of the Baltimore seam of coal was found. The size of the shaft within the cribbing timbers is 45 feet 4 inches by 11 feet 6 inches, having six divisions of equal dimensions, 7 feet by 11 feet 6 inches, giving room for what is known as the "standard diamond " car, whose capacity when level full is 100 cubic feet, but when loaded by the miner 4 inches above the top contains 112 cubic feet." Two divisions of this shaft are intended for hoisting coal from the Hillman seam, two from the Baltimore seam, one for ventilation, and one for pumps. The works were planned for two pairs of direct-acting, high-pressure engines, twenty-four boilers, and for an estimated output of 2500 tons of coal per day from the two seams.

By A. J. Jacobs, J. W. Spretnak, R. Speiser

The activities of nickel in liquid iron-nickel solutions containing from 10 to 90 at. pct Ni were measured over the temperature range .1510° to 1600°C. A special function was devised whereby activities can be computed by a graphical integration using the results of chemical analyses on the vapor phase alone. The liquid solutions studied exhibit negative deviation from Raoult's law, but they approach ideality as the temperature is raised from 1510° to 1600°C. The maximum heat of solution is less than -8.0 kcal per mole. The entropy of solution is less than —2.5 kcal per mole deg at 1510°C, and changes negligibly as the temperature is raised. The liquid iron-nickel solutions do not follow regular solution behavior. THE activities of the components of a liquid alloy system can be determined in favorable cases from the partial pressure of the vapor in equilibrium with the liquid alloy.' Assuming that the vapor over the alloy behaves as an ideal gas, the activity of component i is given by the expression, Where the superscripts 1, v, and o signify the liquid, the vapor, and the pure component, respectively; the f's are the fugacities, and the P's, the pressures. The quantities Pi and Pi can be determined by the

Jan 1, 1960

By E. S. Grumell

THE correct sampling of coal and coke is becoming important to an ever increasing number of producers and consumers. This, therefore, may be an opportune moment to examine where we stand with regard to existing and proposed methods. In this paper an attempt will be made to review, as briefly as possible, some of the considerable amount of painstaking research which has been done in the last 10 years, and which has unquestionably led to a much better understanding of the subject. In so doing we shall try, on the one hand, to make clear where substantial progress has been made, and on the other hand, to draw attention to points that require further investigation. The paper is divided into sections in order to emphasize the major divisions of the subject; further, in order to retain this emphasis, detailed consideration of some of the points has been relegated to appendixes. No attempt has been made to give a complete survey of the literature, as this has already been done by L. A. Bushell.2 The following abbrevia-tions will be used: A.E., average error; P.E., probable error; S.W.R., size-weight ratio; B.S.I., British Standards Institution.

Jan 1, 1939

By A. M. Gaudin, Olav Mellgren, P. L. De Bruyn

In commonly used to prepare the surface of the mineral to be floated so that attachment to air takes place. The quantity of agent required to make the mineral hydrophobic is usually very small, of the order of 0.1 to 0.25 lb per ton of mineral. Details of the mechanism of pyrite collection are for the most part unsettled. Adsorption of collector has long been believed to involve an ion exchange mechanism as demonstrated for galena' and for chalcocite. In the work on chalcocite it was also demonstrated that a film of xanthate radicals unleachable in solvents that dissolve alkali xanthates, copper xanthate, or dixanthogen was formed at the surface of the mineral. The unleachable product increased with increasing addition of xanthate up to a maximum corresponding to an oriented monolayer of xanthate radicals. Pyrite is extremely floatable with xanthate if its surface is fresh,,' but the floatability decreases rapidly as oxide coatings increase in abundance. Pyrite shows zero contact angle when in contact with ethyl xanthate solution at pH higher than about 10.5; at neutrality. a contact angle of 60° is obtained at a reagent concentration of 25 mg per liter. Alkali sulfides and cyanides are pyrite depressants.

Jan 1, 1956

By Sukeyuki Mori, Kinjiro Aso, Tsuyoshi Hara, Hisao Okamoto

A theoretical calculation of the electro-osmotic circulation of liquid in a rectangular micro-electro-phoresis cell was presented by Smoluchowski (1921) and Komagata (1933). According to their theories, the velocity of liquid changes with depth such that the velocity distribution may be represented by a symmetrical parabola in the cell. Their theories appear contrary to the results of our experiments which show that the velocity distribution curve is represented by a symmetrical parabola whose symmetrical axis is displaced from the center line of the cell. A similar phenomenon had been suggested by Lane and White in 1937 based on the latter's theory which seemingly was incomplete. By using methods of measuring electrophoretic velocities based on the above three theories, serious errors are obvious. We are thus proposing a unified theory for determining the electrophoretic velocity of mineral particles in a rectangular cell. The equations of Smoluchowski, Komagata and White can be derived from our theory as special cases. On the basis of our theory, we are proposing an improved method of determining the precise electrophoretic velocity of mineral particles based solely on the coefficients of the velocity distribution curve. In our experiments, this method gives satisfactory results. We determined the relation between the zeta-potential and pH value of suspension for several minerals.

Jan 1, 1980

By Hamilton Wingate

In his paper on the hydraulic mining of a low-grade gravel in California,* Mr. W. H. Radford expresses the hope that other members of the Institute will contribute, for the benefit of all, their experience in similar lines. In these notes 1 shall describe the conditions and results of the operation of the Gold Bug Mining Co., of Cleveland, O., at Georgetown, Eldorado county, Cal.

Jan 1, 1903

By Stephen Krickovic

AS it is commonly understood in the bituminous coal mining industry, pillaring means removal, as completely as is practical, of all pillars formed in the development of headings and rooms on first mining. The degree to which this can be accomplished, termed percent of recovery, is of course dependent generally upon the physical conditions of the bottom and the overburden, the system of min-

Jan 1, 1956

Discussion of the papers of Benjamin Talbot. E. A. Beck, Emil Gathmann, Sir Robert A. Hadfield, and P. H. Dudley, presented at the New York Meeting, February, 1913, and printed in this Bulletin (No. 76, April, 1913). CHAIRMAN JAMES F. KEMP :-I call upon Prof. Albert Sauveur to open the general discussion on the subject of sound steel ingots. ALBERT SAUVEUR, Cambridge, Mass. :-I believe that I have the privilege, this instant, of opening one of the most important, significant and far-reaching discussions ever held before this Institute. I believe that our talk this morning will be heard far and wide, not only on this side of the water, but also on the other side. Everywhere, in short, where steel is manufactured. I welcome the opportunity of expressing my mind in regard to the production of sound steel ingots, a subject about which I entertain some very decided opinions. I shall not attempt to discuss the relative merits of the various processes that have been described. I shall, on the contrary, confine myself to a general consideration of the important questions before us. So intensely do I feel regarding the production of sound steel ingots that I have put my remarks on paper in my desire to present my Views.

Jan 4, 1913

His face wreathed in smiles, J. Richard Lucas, Chairman of the Keynote Session, conceded that "the papers appeared to have been of some interest." This was a modest description of the opening day of technical sessions at the SME Fall Meeting and Exhibition, October 13 to 15, in Tampa, Fla. The auditorium had capacity for 800 spectators and there was hardly a vacant seat visible. The topic, Resource Development of the Fertilizer Minerals, was covered in four authoritative papers. H. S. Ten Eyck set the stage. Resources are always viewed in relation to future requirements, and these depend largely on population. If the population trend continues, the world's 3.3 billion people will increase to 6.7 billion people by the year 2000. About 70% of this increased population will be in developing areas which are not capable of supplying sufficient food and fiber for their needs. Fertilizer is a means of bridging the crop shortage. Projections of fertilizer requirements by 1970 are from 53 million to 67.5 million long tons of plant nutrient which compares with 1964 consumption of 37.7 million tons. Looking ahead to 1980, the growth continues with an estimated demand of 80 million to 113 million tons combined of N P and K.

Jan 12, 1966

Major William R. Grunow, in a brief account off his military services, says: "I take pleasure in informing you that since my return from France I have been stationed at Camp A. A. Humphreys, Va., and am now on duty as a Senior Instructor at the Engineer Officers' Training School. While in France, I served as a company commander in the 305th Engineers and was later ordered to return to the United States for assignment to new troops. Upon arrival in the United States, I received my majority." P. F. Rodegerdts gives us the following account of his military service: "I enlisted in the Naval Reserve Flying Corps in San Francisco on Feb. 12, 1918. On February 10, I was ordered to Cambridge, Mass., where I was enrolled for the course in technical aircraft construction given at Massachusetts Institute of Technology. After successfully completing the course of instruction, I spent six weeks in practical construction of seaplanes at the Curtiss aeroplane factory in Buffalo. Following this, I was assigned to active service at Akron, Ohio, on June 22, 1918. At the same time I received my commission of ensign U.S.N. R.F. Unfortunately, I have been kept at Akron and although I have made

Jan 1, 1919

For the first time, the attendance at the meetings of the Institute passed the thousand mark; as is shown by the following table: REGIS- AT BANQUET DID TOTAL TERED NOT REGISTER Men :..:... 703 76 806 Women 195 61 256 1062 The names of the members and guests who registered or attended the banquet but did not register are: A A. D. Beers C. A. Adams Hans Behr Thos. J. Adams Edgar G. Bell Lawrence Addicks Donald A. S. Bell H. T. Abrams W. de LeBenedict G. Aertsen G. B. Bertelli M. M. Albertson Charles P. Berkey James Aldrich Clinton Bernard D. C. Alexander, Jr. W. N. Best W. H. Alexander Robert M. Betts A. W. Allen Christopher H. Bierbaum F. D. Aller Paul Billingsley R. H. Allport R. A. Bingham F. C. Alsdorf R. M. Bird Capt. M. Altmayer John L. W. Birkinbine A.' W. Ambrose G. S. Bisey Henry M. Ami Charles W. Boise F. L. Antisell J. J. Blackmore R. S. Archer A. E. Blackwood Paul' Armitage Capt. C. K. Blatchly Andrew B. Armstrong E. L. Blossom Clifton T. Armstrong C. A. Bohn Ralph Arnold James M. Bonsall R. M. Atwater, Jr. E. E. Boon Joseph E. Aue Gail Borden A. M. Austin R. S. Botsford W. S. Ayres John M. Boutwell

Jan 4, 1919

By P. Somasundaran, D. R. Nagaraj

This study initiated to explore the potential of commercial chelating extractant for beneficiation of minerals revealed "LIX "65N to be an excellent collector for cuprite and chrysocolla. The collector action of the LIX is proposed to result from its chelation with copper species on the surface of the minerals. Thus, the syn-isomer of LIX65N, which is unable to form a chelate with copper ions, failed also to act as a collector. The proposed mechanism takes into account partitioning of LIX between the mineral surface (to form a surface chelate) and the copper chelate dispersed in the bulk aqueous phase (either due to formation of the chelate with dissolved copper, or due to detachment of chelate formed at surface). The efficiency of the collection is dependent upon this partitioning since the bulk chelate is found unable to collect. The marked decrease in flotation obtained when copper was added to the system supports this mechanism. The dependence of flotation of chrysocolla and cuprite on pH and reagentizing time is discussed on the basis of the proposed mechanism. Batch laboratory flotation tests using synthetic mixtures of oxide, sulfide and mixed oxide-sulfide copper minerals with quartz demonstrated the ability of LIX to separate the copper minerals from quartz.

Jan 1, 1980

By Vernon F. Swanson

An equation has been developed which will permit the direct determination of free settling velocity of any sized particle encountered in mineral benefici-ation. The equation is based on Newton's Law with the friction factor defined as a function of the laminar boundary layer. Development of the equation is described first from an empirical trial-and-error approach. Examples are given of actual settling data from the literature versus calculated data to prove the validity of the new equation. Newton's law of resistance of a fluid to flow around a sphere is expressed in Eq. 1. Free settling velocities can be determined by setting Eq. 1 equal to the gravitational force on a particle and solving for V. Experience has shown that when the solids are greater than 1 mm in diam, or when Reynold's number for the system is greater than 800-1000, the friction factor term, fD, essentially becomes a constant, and Eq. 2-b becomes Newton's equation for free-settling and is applicable under the conditions stated. Another special condition exists for particles smaller than 0.05 mm or when Reynold's number for the system is less than three. In this case fD=24/NRor24µ/pL,dV,. Eq. 2-b can then be rewritten as

Jan 1, 1968

Meeting of Nov. 21, 1913.-The President reported the appointment of the officers and members of the Committee on Non-Metallic Minerals, published elsewhere in this Bulletin. The President appointed the Executive Committee of the New York Section as a local .committee to have charge of the Annual Meeting of the Institute in February, 1914, with power to add to their numbers. It was voted that the Chairman of each Technical Committee, be made ex officio a member of the Committee on Papers and Publications. At the request of the Secretary, Burr A. Robinson was appointed Assistant Secretary of the Institute. E. Gybbon Spilsbury was nominated as representative of the Institute on the John Fritz Medal Board of Award. It was voted that the next summer meeting of the Institute be held in Salt Lake City in August, 1914, with power to the Executive Committee to fix the exact date. Substantial reduction was made in the price of the back Transactions of the Institute in accordance with the notice published on p. i of this Bulletin.. The By-Laws of the Montana Local Section were approved. The printing contract for the year 1914 was made with the Maple Press. Thirty-eight Members, one Associate and three Junior Members were elected.

Jan 12, 1913