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By AIME AIME

MINERALS and mineral resources are recognized as one of the things that nations are prone to quarrel about. The territory that was arbitrarily incorporated into the Polish Republic after the World War produces a variety of essential minerals on a substantial scale. The accompanying table has been compiled to give some idea of the relative importance of this production. Poland, before the recent war started, had an area of 150,000 sq.mi., just a little larger than the State of Montana. Its population was 32,000,000, equal to that of New York, New Jersey, Pennsylvania, Connecticut, and Massachusetts. Though not a highly industrialized country it nevertheless has important mines, steel plants, petroleum refineries, and sundry metal-fabricating manufactories. Coal, petroleum, iron and steel, zinc, lead, pyrite, potash, and salt are produced in excess of the country's domestic consumption. It has no appreciable production of copper, chromium, tungsten, nickel, tin, mercury, manganese, aluminum, magnesite, fluorspar, or graphite.

Jan 1, 1939

By Richard L. Ash, Thomas E. Pearse

Most theories of blasting phenomena are based on the condition that explosive charges have a spherical shape. If a cylindrical charge is considered, the explosive is usually assumed to have an infinite velocity of detonation. Another limitation is also often imposed whereby only one free face is considered to exist. Unfortunately, these conditions all serve to limit the number of variables involved and tend to over-simplify analyses. The result is that explanations for actual effects from blasts are seldom realistic. In addition, no solution has yet been found to explain the actions of certain blasting agents that appear to stress materials in a different manner than do many of the high explosives. In order to determine causes for some of the unexplained phenomena, investigations were conducted by the writers on both actual field blasts and theoretical problems. Although many solutions have been proposed to explain the rock breakage processes, none relate the effects of hole depth, explosive and rock energy- propagation velocities with charge placement geometry. Evidence indicates there is a definite interdependence of those factors and that they are of vital importance in proper drill-pattern design. For simplicity most of the discussion in this paper applies to vertical blast-holes drilled in uniform massive rock for open pit blasting, although the basic principles presented apply to all forms of blasting with certain basic modifications being necessary for specific field conditions.

Jan 9, 1962

It has been established that molybdenum sesquisulphide, not molybdenite, is in equilibrium with molybdenum metal and sulphur vapor in the vicinity of 1100°C. The S2 pressure for this system has been obtained using the Knudsen orifice method and the standard free energy for the dissociation of S2. THIS work was undertaken to help in determining the thermodynamic properties of the molybdenum sulphide which is in equilibrium with metallic molybdenum and sulphur vapor in the temperature range 1025" to 1150°C. From the results of MontoroL and of Parravano and Malquori' molybdenite would be expected to be in equilibrium with molybdenum metal, while the results of Guichard indicate that a lower sulphide must be in equilibrium with the metal. Thus it was concluded that the problem warranted reconsideration, especially in view of the suspiciously low temperature independent term for the standard free-energy function for the reaction MoS² Mo + S,. The reaction was calculated and duly noted as being low by Richardson and Jeffes,' using the data of Parravano and Malquori.' Experimental Method The general method used in this investigation is that of the Knudsen orifice method for the determination of equilibrium pressure. The apparatus and technique are similar to those described for the determination of the vapor pressure of silver.% owever, a closed-end McDanel tube instead of fused silica was used to maintain the vacuum, a molybdenum effusion cell with a replaceable lid was employed instead of a silica cell, and a titanium getter maintained at run temperature was used to assure that no oxidation of the molybdenum or molybdenum sulphide was taking place. All runs were made at a residual pressure less than 10-5 mm Hg. The data are given in Table I. Runs 1 through 13 were obtained using molybdenite, analyzed 98.5 pct, from the Molybdenum Corp. of America. The remaining runs were done with a sample from the Climax Molybdenum Corp. which was their grade No. 3 and analyzed 59.87 pct Mo. The weight loss of the cell during heating up and cooling down was subtracted from the total weight loss of the cell during the run. Also, when the tem- perature was changed, the Knudsen cell was placed in the vacuum chamber and heated at temperature for several hours in order to allow the sulphide and the metal to adjust their compositions to the equilibrium values, to desorb or adsorb gases into or from the molybdenum cell itself, and to desorb any water from the molybdenum sulphide or molybdenum powder inside the cell. Water may have been adsorbed inside the cell because, after each run, the top of the cell was removed and the material in the cell was stirred to insure that a layer of molybdenum metal would not build up and obstruct the passage of sulphur vapor into the gas phase. It was established that the molybdenum cell alone decreased in weight an inappreciable amount when heated at the highest run temperature for long periods of time. There are two questions to be answered before the data in Table I can be used to calculate thermodynamic functions: 1—Which molybdenum sulphide is in equilibrium with molybdenum metal and sulphur vapor? 2—What sulphur species are present in the vapor phase? It can be assumed safely that no molybdenum is vaporized, since its vapor pressure is almost negligible at these temperatures. It will be shown subsequently that no sulphide of molybdenum is volatile. Question 1 was answered in the following way: The especially purified molybdenite, obtained from the suppliers mentioned previously, was charged

Jan 1, 1956

By P. Chiotti, E. R. Stevens

The electromotive force between pure magnesium and Mg-Zn alloys in a fused KC1-LiCl-MgC12 cell was measured over the temperature range 360° to 730°C and for alloy compositions of 0.052 to 0.635 atom fraction magnesium. The calculated activity coefficients of magnesium in the liquid alloys may he represented by the relation These data and the phase diagram were employed in calculating the standard free energy of formation for the compounds MgZn, MgZn2, and MgZn2, In the temperature range from 25° to 590°C the relation ZINC-rich magnesium alloys have been shown to be very effective in reducing various solute chlorides or oxides from fused salts such as KC1-LiC1 eutectic. Such reactions are of interest in the developinent of pyrometallurgical methods for reprocessing nuclear reactor fuels.' As the conceniration of the magnesium is increased beyond 5 to 10 wt pct the extent to which solutes, such as yttrium, lanthanum, cerium, and other rare earths, can be reduced or removed from the salt decreases. This effect is due to the resulting change in the activity of the solutes in the Zn-Mg alloy as well as the change in the activity of both the zinc and mag- nesium. The purpose of the present investigation was to determine the thermodynamic properties of the Zn-Mg system which, in addition to yielding information on the alloying behavior of these two elements, would permit a more quantitative understanding of the above reactions. Since this investigation was initiated several publications have appeared in the literature giving results on the thermodynamic properties for the liquid alloys of this system. 2-4 Kozuka, Moriyama, and Kushima3 measured the vapor pressure of zinc over four different alloy compositions by a carrier-gas technique. Eremenko and Tukashenko2 and Terpilowski4 measured the electromotive force between pure magnesium and various alloys in a fused salt cell. Earlier work has been summarized by Hultgren, Orr, Anderson, and Kelley.5 In the present investigation electromotive-force measurements were made on a cell of the type The temperature range covered for the lower-melting alloys was roughly 375° to 730°C. These data were employed in calculating the thermodynamic properties for the liquid alloys and in conjunction with the phase diagram,' reproduced in Fig. 1, were used in calculating the standard free energy of formation of the compounds MgZn, MgZn2, and Mg2 Zn11. The results obtained are compared with available data from the literature. MATERIALS AND EXPERIMENTAL PROCEDURES Materials employed were: Bunker Hill slab zinc, 99.99 pct pure; Ames Laboratory magnesium containing 13 ppm N, 195 ppm C, and trace amounts of calcium, copper, nickel, and silicon; reagent grade KC1, LiC1; and high-purity MgC12 obtained from Dow Chemical Co. The electrolyte consisting of KC1-LiCl eutectic (44.4 wt pct LiC1) to which was added 15 wt pct MgCl2, was dried in a quartz tube by heating to 340° C under vacuum for a period of 4 to 5 hr, and then passing HC1 through the salt as the temperature was slowly raised to above the melting point of the salt. After about 3 hr the HC1 was shut off and the system flushed with argon and then vacuum applied for 1 hr. The salt was finally siphoned through a sintered glass filter and cast into a Pyrex container which was sealed and

Jan 1, 1965

By AIME AIME

THE Coal Division holds its fall meeting in the Pocahontas coal field, at the West Virginian Hotel, Bluefield, W. Va., Oct. 9 and 10. The first day will be a busy one-two sessions for the presentation of papers and a dinner in the evening. Hon. E. Fudge, Assistant Undersecretary, Mines Department, and R. V. Wheeler, head of the Mines Research Board of Great Britain, will be the guests of the Division. Mr. Wheeler will discuss the British Mining Act as relates to the coal industry. George S. Rice, Chief Mining Engineer, U. S. Bureau of Mines, will present an account of the recent meeting at Buxton in England, of representatives of England, Germany, France, Belgium and the United States to formulate a plan and to correlate research work now in progress in the various countries. The second day the members will be the guests of the operators on a trip through the Pocahontas field. The work of preparation for the meeting is being actively pushed by committees headed by T. H. Clagett, R. M. Lambie and H. D. Smith, and a good attendance, both local and from the general membership of the Division, is anticipated. Because many will make the trip by car the principal automobile as well as rail-road connections to Bluefield are given here. The program for Friday, Oct. 9, follows:

Jan 1, 1931

By Bradley Stoughton

A LL over our great country I have been privileged to see, during the last six weeks, the manifestation of a new spirit among engineers. Partly under the inspiration of leaders whose influence has been felt not only nationally, but internationally, - partly through the recognition of the service that engineers have been able to render to the nation during the recent crisis, a new self-consciousness has been acquired by the individuals, and now this self-consciousness seeks expression in opportunities for service and participation in public affairs. The engineer . no longer sees himself a mere reservoir of information to be tapped when some one is in need of cold facts, no. more an administrator of mere material things, but a potential administrator of- public affairs, a citizen and a human being, with the responsibilities, as well as the privileges of citizenship.

Jan 1, 1920

By R. J. Corfield

MODERNIZATION of the entire electrical system and improvement of Rotation process efficiency is the twofold goal of the improvement program underway at the Arthur and Magna concentrators of the Utah Copper Div., Kennecott Copper Corp. Copper ore from the Bingham pit goes to these two concentrators where an interlocking program calls for complete electrical modernization and increased flotation process efficiency through additional capacity and flow scheme revisions. Flotation plants at the two mills are essentially duplicates, and while this article deals with the changes at the Arthur mill similiar improvements are being made at the Magna mill.

Jan 3, 1953

By Donald L. Everhart

SOONER or later intelligent exploration for uranium leads to these questions: Where did the metallic ions that formed the orebodies come from? What processes and geologic factors were involved in ore replacement? These matters, of course, make a big difference in how best to look for orebodies. Before these questions are discussed it might be well to point out other factors bearing on the subject. The whole business of uranium exploration is only a little over ten years old, participation by the public is only about six years old, and real interest and activity by more than a few large mining companies has arisen only in the past two or three years. Throughout this short period, uranium exploration has been affected by the unique influences of necessary security measures and by division of the over- all job into individual projects by a large number of specialists in diverse fields. This has meant that a normal interchange of information on the nature of uranium deposits has really only just begun. Com- pared to the vast amount of published studies on iron, copper, lead, zinc, and gold deposits over the past 50 to 75 years, current knowledge of uranium deposits is in its infancy and much of the pertinent information is still scattered about in a number of unpublished sources. The volume of reports on all phases of uranium exploration is now beginning to mount at a remarkable rate, and geologists with widely varying specialized backgrounds in uranium geology are engaging in spirited debates over the origin of uranium and the relative importance of geologic controls of various deposits.

Jan 9, 1954

By AIME AIME

The 102d meeting of the Institute was held at the Institute headquarters in the Engineering Societies Building, New York, N. Y., on Feb. 19, 20 and 21, 1912. A Bureau of Information, in charge. of Mr. George Buckman, was maintained during the meeting. The proceedings opened with an informal social meeting on Monday evening, Feb. 19, in Assembly-Room No. 1, on the

Mar 1, 1912

By E. V. Murphree

CREATION of atomic energy, aside from its influence on war or peace, has posed these basic questions for the world: How soon can energy from atoms be harnessed to do man's daily work? How much of this power will there be, to what degree will it supplant present fuels, and what does it imply for the future of civilization? Answers to these questions may be found in part in analysis of just what atomic energy is and how far its development has come. The answers are encouraging. One of the first questions encountered in considering the application of atomic reactions is whether such reactions can be controlled. Fortunately, this has been adequately demonstrated by the operation of the Government plutonium plants at Hanford, Wash. Here nuclear reactions are carried out on a large scale involving liberation of about a billion B.t.u. per hour. This hourly heat liberation is equivalent to that obtained from about 7100 gallons of fuel oil. It has been possible to operate these plants day in and day out with the reaction controlled at the intensity desired. There should therefore be no question that, under proper conditions, reactions involving nuclear fission can be controlled.

Jan 1, 1946

By J. L. Fitch, B. G. Hurd

The presence of gypsum in samples subjected to standard core analysis introduces serious errors in the measurement of water saturation and porosity. The magnitude of these errors, depending upon the type of analysis procedure used, has been evaluated experimentally and theoretically. Water-saturated pore volumes determined by vacuum distillation or retort procedures may be too high by as much as 48 per cent of the volume of gypsum present. The maximum error in this value determined by Dean-Stark extraction with toluene is 36 per cent of the gypsum volume. If pore space is measured by a Boyle's law type porosimeter the maximum erorr due to gypsum is 38 per cent of the original gypsum volume present. The conscientious core analyst may eliminate the errors caused by gypsum by either of two methods. He may apply suitable corrections for the water of crystallization removed from gypsum, or take special precautions to prevent dehydration of gypsum during core cleaning and alzalysis procedures. These alternatives are discussed and methods for obtaining reliable core analysis data are proposed. Gypsum (CaSO4 . 2H2O) occurs as a common mineral in many of the world's sedimentary basins. In addition to its presence as primary bedded evaporitic deposits, it is often found as secondary replacement zones and pore-fillings in host rocks. That it may cause false indications in porosity, both on neutron logs and in standard core analysis, has been generally recognized. False porosity interpretations from neutron logs result because the chemically bound water in gypsum attenuates neutrons as effectively as free water. Errors in core analysis result when gypsum is dehydrated prior to or during the analysis. Vacuum retort procedures used by many laboratories to determine fluid saturation and porosity effect a complete removal of water of crystallization from gypsum. The crystal water, distilled and collected with free water from the sample, is counted as water-sat11rated pore space. Dehydration of gypsum results in a decrease in volume occupied by calcium sulfate and a corresponding increase in pore volume. Thus, if gypsum is dehydrated by sample cleaning and drying procedures, subsequent porosity measurements with gas expansion or compression instruments will be high. The qualitative effect of gypsum on porosity determinations by retort procedures was discussed in a recent article by Bynum and Koepl3. They concluded that since false porosity was interpreted as being water saturated, determinations of oil content were not affected. Others in the industry, however, have pointed out that porosity values are often used with values of water saturation determined independently, e.g., from electric resistivity logs in making reserve estimates. Values of water saturation calculated from the formation resistivity using the Archie equation, S4= are actually low if values of are high due to gypsum. In this case, false porosity values due to gypsum could cause serious errors in calculations of oil-in-place. This investigation was made to determine quantitatively the effect of gypsum on porosity values determined by different core analysis procedures. EXPERIMENTAL PROCEDURES Dehydration of Gypsum The extent and rate of removal of water of crystallization from gypsum under conditions encountered in core analysis procedures were studied. Taken for the experiments were three types of relatively pure, naturally occurring gypsum, viz. selenite, satin spar and massive gypsum. Although all samples probably contained trace chemical impurities, each type lost the theoretical amount of water upon complete dehydration. An automatic recording thermobalance, similar to one described by Mauer2, was used to obtain dehydration rate data for samples heated in dry air. Water

By Frank G. Breyer

C ONDITIONS have not been favorable for new developments in any line. It has been a period, how- ever in which recent developments have been subjected to the severest tests. Those which have been able to hold their own in the severe competition of 1932 must be considered fully proved commercial processes. The continuous vertical-muffle retort plant at Palmer- ton is reported to have been in operation at practically full capacity throughout the year. The high quality of metal produced and the low operating costs are factors which have kept this plant running when many of the older furnaces were shut down. The plant at Meadow- brook, W. Va., is also reported to have been in steady operation throughout the year. Average retort life is said to be better than two years with about three-quarters of the original retorts still in operation after 2 ½ years.

Jan 1, 1933

By Mitchell, Edmund I.

VARIOUS suggestions as to proper fees for engineering services have been put forth by individual practitioners and by the American Institute of Consulting Engineers, the Connecticut Society of Civil Engineers, the Iowa Engineering Society and the Mahoning Valley (Ohio) Engineers, for the guidance of both the engineer and his client. The American Institute of Architects also has a schedule of minimum charges (revised 1908). So far as can be determined, however, the four national societies representing civil, mining, mechanical and electrical engineering have never given consideration to this question. An examination of technical periodicals published during the past decade shows that these schedules make provision for three methods of charging; i.e., (A) a percentage of the cost of the completed project; (B) a per diem rate; and (C) a fixed sum. Suggested minimum charges are as follows:

Jan 1, 1921

By Philip D. Wilson

AS thin most important and vital component of an airplane aluminum hay rapidly become the heart and tome- of the war program. Its production ham increased amt will continue to increase, in comparison with its pre-war position further than that of any of lie other important critical metals except magnesium. Compared with the 1939 production of tons of primary ingot coming from four plants, all owned by the Aluminum Company of America the 1942 figures are more than three timer as large. Including, recoverable scrap and contracted ingot from Canada the 191,, supply of aluminum for the United States will be over siren times dial of 1939- A substantial part of this increase has been achieved during the past year as total production in 1941 was only some 307,500 tons. During 1942 six great new ingot plants sponsored and owned by the Government have come into production and three others are nearing completion.

Jan 1, 1943

By L. H. E. Weyher

As a result of past developments, mainly at universities, the coal industry has had access for a decade or more to a number of computer programs for coal mine planning. Using some of these programs Bethlehem Steel's Research Department in 1969 launched jointly with Bethlehem Mines Corporation an extensive research and development program aimed at: (1) testing the capabilities of these programs through trial applications as the need and opportunity existed, (2) defining what additional capabilities were required to make mine planning computer systems fully useful in the hands of Bethlehem's mine-planning engineers in the field, and (3) developing and implementing in the field the mine-planning systems agreed on. This program is now nearing completion, and several of Bethlehem's operations routinely use the planning tools that were developed. The progress of this research program is discussed in terms of our initial trial applications of computer methods to mine planning and the incorporation of several innovative features into our new set of computer programs, in particular, the use of time sharing, data base management systems, and general-purpose simulation languages.

Jan 1, 1977

By C. Norman Cochran

The pllnse diagvam for the NaF-AlF3 system was used to calcutate an ionic model for the NaF-AlF3 system. Assuming an ideal solution,a series of simultaneous equations expressing equilibria be-tween solid and liquid phases at the euleclic, perilec-tic, and melting points were solved for the activities of the ionic species, the dissociation constants, and the entropies and heats of fusion. The calculations suggest the existence of A13F1415 ions in addition to the F-1+AlF6-3 , and AlF4-4 ions previously proposed by others. The calculaled valnes give better agreement with vapor pressures than the previous model without Al3Fl14-5. Additional possible vefinements of the model are proposed. CRYOSCOPIC1 investigations and density data2 for the NaF-A1F3 system have previously been used to study the dissociation mechanism of Na3A1F6 and to derive equilibrium constants for its dissociation to NaF and NaAlF,. Depending primarily on the heat of fusion assumed for cryolite, the dissociation constants ranged between 0.02 and 0.18 from cryoscopic studies, and from 0.09 at 1273°K to 0.16 at 1363°K from density data. In most cases the values were unable to reproduce satisfactorily the experimental liquidus lines very far on the A1F3 side of the Na3A1Fe composition. This suggested the existence of at least one other ionized compound in the melt besides NaA1F4 in the Na3A1F6-A1F3 side of the system. This is assumed to be liquid Na&13F14 (chiolite), which is already established as a stable solid in phase studies of this system. MODEL FOR THE MELT The melt is assumed to be an ideal solution with ion activities equal to anion fractions. The only cation in the model is sodium so that Temkin and simple anionic activities are identical. Although the compounds are completely ionized to Na' and the respective anion in the melt, molecular rather than ionic notation is used throughout this work. The Na3A1Fe is assumed to dissociate to NaA1F4 and NaF as in the former model, and Na&13F14 to dissociate to Na3A1Fe and NaA1F4. Other valid dissociation equilibria can be written involving these four compounds, but all of these can be obtained by combinations of the two described dissociation reactions and, thus, are automatically considered in these calculations. The model allows for no free AlF3 so that compositions for NAIF3 > 0.5 (mole fraction A1F3 on the NaF-A1F3 basis) cannot be treated. The question of the existence of free AlF3 in the melt will be discussed again later. The constants in the model were evaluated from points along the entire known liquidus line of the NaF-A1F3 system. Previous work employed only the liquidus line or densi- ties near the Na3A1F, composition. The liquidus line compositions used in the solution of the model are from unpublished work by Mr. P. A. Foster, Jr., for compositions between the Na3A1F6 melting point and the Na&13F14-A1F3 eutectic, and from the published works of Grjotheim,1 Phillips,3 and Foster4 for the remainder of the system. The relationships used in solving for the desired dissociation constants and heats and entropies of fusion are listed in Table I, and the points along the liquidus line at which each apply are indicated to the right of the relationships. The mole fractions of each of the separate species in the melt are symbolized by N. Relationships [I] and [2] are the respective dissocia-ation constants, Kl and K2, of Na3AIF6 and Na5A13F14 for this model. For simplicity, these constants will be assumed to be independent of temperature. Relationship [3] follows from the assumption of the ideal solution. The expression relating the values of N to the experimental values of NAIf3, is given in Relationship (41. Relationships [5], [6], and [7] each state the equilibrium between a compound in the melt and its pure solid phase for the portion of the liquidus lines where it precipitates. The heats of melting, AH,, and entropies of melting, AS,, used in [5], [6], and [7] are assumed to be independent of temperature. The compositions and temperatures of all five invariant points (two melting points, two eutectics, and one peritectic) along the liquidus lines from NAIF3 = 0 to NAIF3 = 0.5 were employed in the solution. The eutectic and peritectic compositions were particularly useful because each of these is involved in one more equation than other points along the liquidus lines and thus reduces the number of points required to solve for the constants. Also, their use assures that the inflection points in the derived liquidus line will correspond exactly with those on the experimental liquidus line. The total number of equations is 5k1 — 1, where n is the number of experimental composition points used. The number of unknowns is 4n + 5 (4n- 3 values of N, 3 values each of AH, and AS,, and 2 values of K). Thus, six points must be used in the solution to obtain an equal number of equations and unknowns. The one additional required experimental composition was taken on the liquidus line between the Na3A1Fe melting point and the Na3A1F6-Na5A13F14 peritectic. Previous work indicated this was a difficult portion of the curve to fit. The temperature used for the point was 1161°K, the same as for the NaF-Na3A1Fe eutectic. This choice of temperature gave two points with identical NNa3AIF6 values which simplifies the algebraic solution. The second point at this temperature is denoted 1161°'K. PROCEDURE FOR SOLUTION OF EQUATIONS Values were assumed for NNa,AIF and NNaF at the NaF-Na3A1F6 eutectic at 1161°k. By an iterative procedure, the corresponding values for NNa5A13F14 and NNaAlF4 at 1161°K were determined from 131 and 141. A value was assumed for NNaAlF4 at 1161°'K and

Jan 1, 1968

By Arthur S. Dwight

THE professional career of Thomas Septimus Austin, who died at El Paso, Tex., August 23, 1906, was contemporaneous with the growth of the silver-lead smelting-industry of the Far West, to which his talents and zeal contributed in no small degree. Born at Stratford, Conn., December 7, 1853, he was the seventh son in a family of thirteen. His parents were well-to-do; and he received a thorough preliminary training at the Hopkins Grammar School, New Haven, Conn., passing thence to the Columbia School of Mines, in New York, where he was graduated in 1876. His first professional work was that of analytical chemist with a Cuban sugar company. In this position he spent a year, and, whatever else of benefit he may have acquired during that year in Cuba, he gained a facility of speech in the Spanish language which was of inestimable value in his subsequent work in Mexico and the southwestern United States. In 1877, he went to the Rocky Mountains, and, under the firm name of Murphy & Austin, opened an assay-office in Leadville, Colo., which was just then coming into public notice as a rich silver-lead camp. The next year, however, he entered the service of the Germania Smelting & Refining Co. at Salt Lake City, Utah, where he remained until 1882, first as assayer and chemist, and later as Assistant Superintendent. The Germanic bears the honorable distinction of being one of the first of the large " custom " lead-smelters erected in the West. Its founders may be called the pioneers of the modern lead-smelting practice, and the Germania served, to a large extent, as a model for the many plants that sprang into existence during the next few years in Utah, southern Idaho, Colorado and other lead-producing districts. The formulation, for the first

Jan 1, 1908

By P. Chiotti, J. T. Mason

Ther?nal, X-ray, metallographic, and vapor pressure data were obtained to establish the phase diagram and standard free energy, enthalpy, and entropy of formation for the compounds in the Sw-Zn system. Four compounds, SmZn, SmZn2 , SmZn4.s, and SmZn8.5, melt congruently at 960°, 94Z°, 908°, and 940°C, respectively. The cornpounds SlnZns, Sm3Znll, and SnzZn7.3 undergo peritectic decomposition at 855", 870°, and 890C, respectively. Another compound of uncertain stoichiometry, SmZn11, undergoes peritectic decomposition at 760°C. Four entectics were observed with the following compositions in weight percent zinc and eutectic tenzperatures in degrees Centigrade: 12 pct, 680°C; 36 pct, 890°C; 58 pct, 850°C; and 72 pct, 900°C. An allotropic transformation and a composition range were observed for the SmZnz compound. The transfor)nation varies from 905" to 865°C as the zinc content increases from 16.0 to 48.5 wt pct, respectively. The free energy of formation of the compounds at 50PC varies between -15.9 kcal per mole for SmZn to -51.1 kcal per mole for SmZn,.,. Corresponding enthalpies vary between -19.2 to -78.3 kcal per mole. The ther-modynamic properties for the liquid alloys are described by the relations: A search of the literature revealed very little information on the Sm-Zn system. Chao et al.&apos; as well as Iandelli and palenzonai have reported the structure of SmZn to be cubic B2 type and Kuz&apos;ma et al3. have reported the structure of -sm2zn17 to be of the Th2Ni17 type. The purpose of this work was to establish the phase diagram of this system, to determine the zinc vapor pressure over the solid two-phase regions of the SYstem, and to calculate the thermodynamic properties of the compounds. MATERIALS AND EXPERIMENTAL PROCEDURES The metals used in this investigation were Bunker Hill slab zinc 99.99 wt pct pure and Ames Laboratory samarium. Analysis of the samarium by chemical, spectrographic, and vacuum-fusion methods gave the following average impurities in ppm: Nd, <200; Eu, <100; Gd, <100; Y, <50;Ca, 225; Ta, 400; Mg, 10; Cu, ~50; 0, 175; H, 20; and N, 15. The elements Fe, Si, Cr, Ni, Al, and W were not detected. The samarium was received as sponge metal and was kept under argon except when being cut with shears and when being weighed. Tantalum was found to be a suitable container for alloys with zinc contents up to the Sm2Znl, stoichio-metry. At higher zinc contents the grain boundaries of the tantalum containers were penetrated by the alloy and the containers failed during prolonged annealing. About 25 g of massive zinc and samarium sponge were sealed in tantalum crucibles equipped with thermocouple wells. These crucibles were in turn sealed in stainless-steel jackets. All closures were made by arc welding under an argon atmosphere. The samples were equilibrated in an oscillating furnace and in some cases were given various heat treatments in a soaking furnace. After appropriate heat treatment the steel jackets were removed and the alloy subjected to differential thermal analysis. The apparatus was calibrated against pure zinc and pure copper and found to reproduce the accepted melting points within 1°C. Alloys were subsequently subjected to metallographic examination and those of appropriate compositions were used for X-ray diffraction analysis and for zinc vapor pressure determinations. The vapor pressures were determined by the dewpoint method. Both the differential analysis and dewpoint measuring apparatuses have been described in earlier papers.4, 5 All alloy samples were etched with Nital (0.5 to 3 pct nitric acid in alcohol) except the samarium-rich alloys. These more reactive alloys were electro-polished in a 1 to 6 pct HClO4 in methanol solution at -700c at a potential of 50 v. EXPERIMENTAL RESULTS Phase Diagram. The results of thermal analysis are indicated by the points on the phase diagram, Fig. 1. Eight compounds and four eutectics were observed. The composition of the compounds and their melting or peritectic temperatures are given on the phase diagram. The four eutectic compositions in wt pct zinc and eutectic temperatures in % are: 12 pct,- 680°C; 36 pct, 890°C; 58 pct, 850°C; and 72 pct, 900°C. The stoichiometry of the most zinc-rich compound is still uncertain, but is very likely either SmZnll or SmZnlz. However, to simplify the presentation which follows it will be referred to as SmZnll. As shown on the phase diagram the phase regions for some of the samarium-rich alloys have not been unambiguously established. A sample of pure samarium was observed to transform at 924°C and to melt at 1074"C, in good agreement with corresponding val-

Jan 1, 1968

By A. W. WALKER

All branches of production engineering showed steady and definite progress during 1941. Most of it has been of the slower and more conservative type rather than the sensational. To a large degree the changes have been influenced by the expanding war economy, and this tendency will probably be even more marked during the coming year. The stress of the times is placing more emphasis on the principles of engineering and conservation, with the object of obtaining the greatest possible recovery with a minimum waste or expenditure of equipment. Also available material supplies are often being turned to new uses.

Jan 1, 1942

DeLamar, the largest silver mine in the United States outside the Coeur d’Alene District in Idaho, came into production in April 1977. It is a joint venture of Earth Resources Company and Canadian Superior Oil Co., with Earth Resources being the operator. The property is a consolidation of several old operations dating back to the 1800s; the better known of these are the DeLamar and Sommer-camp mines. DeLamar is situated in southwestern Idaho near the Oregon border in the Owyhee Mountains, 88 km (55 miles) southwest of Boise, Idaho. Heavy snowfalls and very low temperatures are common in the wintertime. Planned production was 77,500 kg (2.5, million oz) of silver and 5 13 kg (16,500 oz) of gold per year. Expected life at a milling rate of 1,540 mtpd (1,700 stpd) was 20 years, with an ore grade of 144 g Ag and 1.58 g Au per mt (4.2 oz Ag and 0.046 oz Au per st). Present production is at the rate of 1,900 mtpd (2,100 .stpd). The total cost to bring the mine into production was reported to be approximately $22 million, and the mill was reported to have cost about $10,000 per daily ton of design capacity. At DeLamar, naurnanite (Ag2Se) is the principal silver .mineral occurring with acanthite (Ag2S) disseminated through quartz veins and a silicified rhyolitic ash-flow tuff of Miocene age. The mineralization is relatively iron and manganese free and is readily amenable to cyanidation giving recoveries of 85% silver and 92% gold, which occurs free. When the plant was started, considerable difficulties were encountered in handling the wet sticky ore because of the high clay content. Following primary crushing, the ore is stockpiled. Due to the sticky nature of the ore, the vibrating feeders initially installed under the stockpile were replaced by a reclaim hopper and an apron feeder which was fed 24 hours a day by a front-end loader. The minus 200 mm (8 in.) ore is fed to a 5.5 m by 2.75 m (18 ft by 9 ft) autogenous mill followed by a 2.75 m by 4.57 m (9 ft by 15 ft) ball mill and cyclones. The mills are equipped with 750 kw and 520 kw (1,000 hp and 700 hp) motors. Both mills discharge to the same cyclone feed sump and a portion of the cyclone underflow is returned to the autogenous mill. Cyclone overflow, which is 20% plus 74 microns (200 mesh), is leached in four agitators in series for 72 hours (45 hours at the 2,100

Jan 1, 1981