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By Simon D. Strauss

What are future prospects for U.S. mining? In many quarters the assumption is made that this country has passed its zenith as a mineral producer -- that it is in a period of decline and that it is becoming a have-not nation like Japan and much of Western Europe. These industrial rivals of ours must depend almost entirely on others for their mineral supplies. In trying to answer this question one must of course distinguish between resources and productive capacity. In today's volatile and competitive markets, the definition of what are reserves and what are merely identified resources becomes ever more difficult. Many large deposits have been found that are unlikely to be viable in the marketplace under normal conditions but that can be of significance to the nation's military and industrial security in times of emergency. I should like to draw on personal experience from World War I1 for illustration. 4fter Pearl Harbor great concern developed over the availability of a long 1ist of strategic materials for which this country was largely dependent on imports. Included were a number of minerals of which domestic deposits had been identified. Among these were chromite, manganese ore, mercury, mica and tungsten.

Jan 1, 1982

By P. G. Sprang, S. Rosen

The Y-Al- C ternary phase diagram for the com -position range from 55 to 100 at. pct Y and for a temperature of 950°C has been constructed from metallographic and X-ray diffraction data. The significant features of the isothermal section which is presented are the small solubility of aluminum in the binary Y3C phase and the presence of a ternary carbide phase with a small homogeneity range around the composition Y3AlC. The similarity in structure and composition between these two carbide phases is discussed in the light of the misci-bility gap which exists between room temperature and 1300°C, which was the temperature range studied. THE occurrence and stability criteria of ternary T3BC, carbide phases having the L'12 structure and the general formula T3BCx have been discussed in detail by stadelmaier1 and more recently by the present authors., Stadelmaier found many representatives of these phases formed between the T metals Mn, Fe, Co, and Ni and the B metals Mg, Al, Zn, Ca, Ge, Cd, In, Sn, Hg, T1, and Pb. The present authors reported on a new series of iso-structural carbide phases formed between the T metals of the Sc group and the B metal, aluminum. These new phases are unique in that many of the Sc group elements form stable binary carbide phases which occur about the composition T3C and which crystallize with a structure similar to that of the T9BCx ternary carbide phases. Furthermore, these binary and ternary phases are found to coexist in equilibrium with each other. The similarity in structure and composition between, for example, Y3C and Y3AlC in the light of the mis-cibility gap which had been found to exist between these two phases indicated a need for a more thorough knowledge of the phase relations which occur in alloys based upon these compositions. Consequently, an investigation of the phase equilibria in the yttrium-rich portion of the Y-A1-C phase diagram was undertaken. The limiting Y-A1 binary diagram determined by Lundin and Klodt3 and the results of Spedding et al.4 governing the Y3C phase were used as guides in , constructing the diagram. EXPERIMENTAL Alloys weighing about 10 g were prepared by arc-melting powder compacts made from the various components on a water-cooled copper hearth using a tungsten electrode in a gettered argon atmosphere. Good homogeneity was obtained by melting the alloys three times. The purity of the yttrium used was 99.9 pct (0.07 pct rare earths). The purity of the aluminum and the carbon was 99.99 pct. The results of chemical analysis on five representative alloys showed that losses during the alloying process were predominantly carbon losses and that in no instance did the measured concentration of this component differ by more than 3 at. pct from the intended composition. For this reason the alloy compositions which are reported are those of the charges prepared for melting. Three alloys which were analyzed for copper, tungsten, nitrogen, and oxygen compositions showed that no contamination had occurred either during casting or during the subsequent annealing treatments. For the major part annealing treatments were carried out on specimens which were placed in

Jan 1, 1965

By Frank S. Hurley

To comply with the California Mine Safety Orders pertaining to transportation of mine workers over mine railroads, the management of the New Idria mine in San Benito County, Calif., designed special man-cars. The new regulations, dated October 1958, make it mandatory for mine man-cars to be designed for carrying five or more men to and from the mine workings. At the New Idria mine, largest single producer of mercury in the U.S., each shift normally employs about 70 men. However, with the possibility of a future increase in the work force, seven man-cars were constructed with a total carrying capacity of 84 men. The general design of the mine man-cars was dictated by safety regulations plus the physical characteristics of the mine-low headroom, limited side clearance in haulageways, and track irregularities due to ground swells. The cars measure 10 ft long, 44 in. wide, and 50 in. high and were built at an average cost of $450 per car. All assembly work was done at the mine site.

Jan 7, 1960

By H. C. Chang, N. J. Grant

Creep of very coarse grained high purity aluminum was studied at 400°, 700°, and 1100°F at initial stresses of 50 to 1200 psi. Local strain measurements were made across the grain boundaries and in different regions of various grains during creep, thereby permitting the drawing of component creep curves. The relative amounts of elongation as measured across a grain boundary and in the grains adjacent to the boundary depend on the temperature of testing. The significance of creep curve equations and activation energies is discussed. THIS paper presents some of the results of a research program devoted to the study of the mechanism of creep in high purity aluminum. Previous publications have dealt with the cyclic processes of alternating grain boundary sliding and migration, and the deformation in the grains caused by these processes;' the direction and the driving force of grain boundary sliding and migration;' the deformation in the grains and the restricting effects of the grain boundaries on this deformation." These previous papers were based mainly on either microscopic observations or X-ray data, or both. Sometimes creep curves across two closely spaced reference marks (about 0.6 to 0.7 mm apart) were also presented with a view to correlating the elongation values with the optical observations in general, and with certain deformation processes in particular. These curves shall henceforth be referred to as component creep curves. No attempts were made, however, to compare either the component creep curves which were obtained in different regions of a specimen, or those obtained from different specimens subjected to different creep test conditions. It is the purpose of this paper to present these component creep curves. Among the factors influencing the behaviors of these curves, those studied were stress, temperature, and grain arrangements in the specimens. It is proposed to show how greatly the deformation can vary from grain to grain and within an individual grain in a coarse grained specimen. The experimental technique and procedure have been presented.' It remains necessary to emphasize that the reference marks were produced by pressing a thin sewing needle into the surface of the specimen before the final annealing at 900°F for 24 hr and at 1150°F for 12 hr. The cold work around the needle indentations was therefore removed. The depth of these holes after electropolishing the annealed specimens was about 0.01 mm. This depth and area were negligible in comparison with the thickness of the specimens, 2.3 mm, and hence would not affect the creep behavior. Results Fig. 1 shows a development diagram of specimen P-8. The dots on the surface locate the needle point reference marks used to obtain the component creep curves. A curve obtained between two dots across a grain boundary measures not only the boundary deformation but also the deformation associated with boundary sliding occurring in the grains in the region between these indents. The original distance between two reference marks was about 0.6 to 0.7 mm. The maximum error of measurement was 0.01 mm, or in terms of percentage elongation, of the order of & 1.5 pct. Whereas the component creep curves shown in the figures to follow were drawn as a gross average of the points, in view of the fineness of some of the steps of grain boundary sliding and migration, as shown in the previous publications,¹,2 it appears logical to expect that some of the finer cycles of movement have not been delineated for the strain sensitivity of the measuring system. It seems justifiable to say that the curves are not as smooth as shown. 700°F Tests: Fig. 2 shows component creep curves across four of the grain boundaries in specimen P-8, tested at 700°F and 85 psi. These curves clearly show alternate cycles of increasing and decreasing

Jan 1, 1954

By I. Iwasaki, P. L. De Bruyn

Electrical double-layer properties of the silver sulfide-solution interface in different electrolytes and the influence the properties exert on the adsorption of dodecylammonium acetate (DAA) were studied using an electrochemical titration technique. The flotation behavior of silver sulfide was observed using DAA as collector and the results were correlated with adsorption measurements. Silver and sulfide ions were identified as the potential determining ions and their adsorption densities were measured as functions of the pAg and of the ionic strength at two different pH values. The point-of-zero-charge (PZC) was observed to be at pAg 10.2, the value being independent of pH and of the nature and concentration of the electrolyte used. The surface charge of silver sulfide in these electrolytes was positive for pAg values less than 10.2 and was negative for pAg values greater than 10.2. The adsorption of amine on silver sulfide surfaces at pH 4.7 was found to be strongly dependent on the pAg. A shift in the PZC towards a lower pAg due to the adsorption of amine indicated a specific affinity of dodecylammonium ion towards silver sulfide surfaces. At pH 9.2 a strong adsorption of the undissociated amine molecule was indicated. The PZC shift towards a higher pAg and the adsorption of the amine was virtually independent of the interfacial electrical conditions.

Jan 1, 1972

By H. I. Aaronson, C. Laird

Cold rolling by 50 pct a A1-4 pct Cu alloy containing many 0' plates has been found to accelerate markedly the transformation of 8' to 0 upon further aging. Although the basic mechanism of this transformation remains unchanged by plastic deformation, the nuclea-tion kinetics of 8 become appreciably more rapid and also less dependent upon temperature. Particularly at lower aging temperatures, rounded idiomorphs replace several faceted rnorphologfes. The rates of growth of 9 idiomorphs in deformed specimens aged at 300°C are appreciably more rapid than simple volume diffusion control allows. This observation is shown to be explained by an excess vacancy, rather than by a dislocation Piping mechanism of growth. ThE rather complex phenomenology of the 8' —8 transformation in Al-Cu alloys has been recently elucidated in considerable detail by means of transmission electron microscopy.'-4 This technique was also employed in the present investigation in order to examine the effects of plastic deformation upon the transformation of 8' to 8. The mechanism of the transformation in undeformed Al-Cu alloys has been established as the following sequence of events.1"4 The first step is the nucleation of 9 at (Y:8' boundaries. Nucleation of a 0 crystal takes place, however, at only a very small proportion of the 8' plates present. Each 0 crystal simultaneously consumes the host 8' plate and the a! in the immediate vicinity, with growth into a being the rate-controlling process. The remaining 8' plates are then dissolved as they fall under the concentration shadow of the growing 8 crystals. The evidence on the effects of plastic deformation upon these processes is intriguing, but much less detailed. The careful X-ray studies of Graf and Guinier have shown that the aging times required to form detectable amounts of 8' and 8 are reduced by prior cold working. Thomas and Nutting confirmed these results by replication electron microscopy. Nile-shwar,* on the other hand, reported that creep deformation decreases the rate of formation of 0. While this difference may have been caused by the use of concurrent rather than successive deformation and ag- ing, the X-ray technique which he used was able to monitor only the 0 phase. It is thus possible that the times needed to form 8' were increased moreg than the kinetics of 8' — 8 transformation were accelerated. At 90 pct deformation by cold rolling, Graf and Guinier found that the usual 0' —0 8 sequence is reversed: 0 forms first. von Heimendahl 10 confirmed this result with transmission electron microscopy. Pollard and Nutting, 11 and more recently Driver and Barrand, 9 having used the same technique, report that 9 also forms first during creep deformation. In the present study, the maximum amount of deformation was limited to 50 pct reduction by cold rolling in order to insure that 8 formed principally by the decomposition of . I) EXPERIMENTAL PROCEDURES This investigation was conducted on an Al- 3.93 pct Cu alloy, prepared as previously described. 4 Morphological and crystallographic effects of plastic deformation were studied in specimens annealed 6 hr at 548°C, quenched, and then aged for either 3 or 8 hr at 250°C to form large numbers of 0' plates. After cold rolling to a 50 pct reduction in thickness, the

Jan 1, 1969

By WILFRED SYKES

IT is with particular pleasure that I welcome the members of the Open-hearth Conference of the I American Institute of Mining and Metallurgical Engineers to this meeting, as I feel this is one of the most useful activities of the Institute in the field of ferrous metallurgy. For the information of our other members I might say the Open-hearth Conference was organized by Mr. Reynders when he was president, and is made up of open-hearth superintendents and metallurgists. All the plants are invited to send representatives, and practically all do, with the exception of the U. S. Steel Corporation. It meets twice a year to discuss various problems in connection with the manufacture of steel, and its minutes are published for the benefit of those attending, the expense being defrayed by the participating companies. This conference, .1 believe, should be a model for activities in the other branches of the work covered by this Institute. It works, not by reading formal papers, which we all know is not a very satisfactory method to bring out the experience of others, but rather by a round-table method of discussion. The spirit of the meetings is such that each member feels perfectly free to state his experience, and he gets as much as he gives. A series of topics for, discussion is brought to the attention of the chairman and after one is exhausted the next point is taken up. In this way there is a real interchange of ideas and experiences which cannot fail l to be of the greatest benefit to those attending. That these meetings are beneficial is evidenced by the "continued growing attendance and lively discussions at these half-yearly meetings.

Jan 1, 1930

By A. L. Moore

KAISER Bauxite Co., a subsidiary of Kaiser Aluminum & Chemical Corp., has been mining and shipping Jamaican bauxite for over a year. On Feb. 10, 1953 the first boat load of bauxite left Port Kaiser, Jamaica, for the company's alumina plant at Baton Rouge, La. To provide its own source of the aluminum ore, a Kaiser Aluminum & Chemical Corp. exploration party started initial reconnaissance in 1947. This work, and subsequent exploration, led to the acquisition of reserves sufficient to warrant a full-scale mining operation for several decades.

Jan 3, 1954

By S. C. Dhara

A process of solvent extraction and separation of platinum group metals (PGM) and gold using primary, secondary, tertiary, and quarternary organic amines has been briefly described. The effects of amine structures; the use of diluents; the principle of synergism and antisynergism in the mixed extractants; the oxidation states of metal ions are explained in the amine extraction process of precious metals.

Jan 1, 1984

By Wilbur E. Sanders

AT some period during the operation of metalliferous and other commercially valuable mineral-deposits in connection with their underground mining, when the developments therein have become so extensive that their description is tedious and confusing, some scheme for naming or numbering the various workings and their parts is necessary for convenience of ; reference.. A simple and symmetrical yet expansive system of classification must be devised, one that is capable of being extended to cover all possible exigencies and conditions of future operations within the property. Such a scheme, properly arranged, greatly simplifies communication between the various departments of the mining business, as, for instance, between the administrative and the operating departments of the concern, and is of the greatest assistance to the officers of the mine in enabling them to locate and describe particular points and parts of workings and specific kinds of work. Again, in the proper segregation and differentiation of mine-accounts, when they are carried out with that detail which will furnish ready information concerning the cost of a particular piece of work, or the various items and totals of expense connected with the, development,, operation and repair of each or all of the mine-workings, some such method of designation becomes a necessity. . Moreover, such a plan is admirably adapted to the needs of the mining engineer, who, in connection with his reports upon mining-properties, is sometimes required, in his descriptions of certain blocks of ore, to locate lists of assays of samples taken from many and various places, and to designate workings and parts of workings that are located in different parts of the mine, sometimes at points wide apart.

May 1, 1906

By Carl W. Volz

NORWAY'S metallurgical development, which has extended over many centuries, is intimately associated with that country's unique topography and climatic conditions. It is a rugged mountainous country, with a most irregular shore line, bordered by thousands of islands forming a natural protection for shipping. There are an endless number of lakes, and innumerable rivers and waterfalls, many fed by glaciers and melting snow. Rainfall is abundant. Though half of the country is north of the Arctic Circle, it is warmed by the Gulf Stream, so that the average temperature is about 45°, or 20° higher than other parts of the world in the same latitude. A sub-

Jan 1, 1935

NEW MEMBERS. The following list comprises the names of those persons who became members during the month of September, 1913: Members. ANDERSON, ANDREW P., Min. Engr 908 Story Bldg., Los Angeles, Cal. ANDROS, STEPHEN 0., Min. Engr University of Illinois, Urbana, Ill. BECKETT, PERCY G., Min. Engr Globe, Ariz. BLAIR, THOMAS S., JR., Prest. Blair Engrg. Co 343 S. Dearborn St., Chicago, Ill. BOYLE, HARRY, Min. Engr S07 Lowman Bldg., Seattle, Wash. BRADEN, EUGENE B., Vice-Prest., Selby Smelting & Lead Co., Merchants Exchange Bldg., San Francisco, Cal. CHALMERS, JOHN W., Min. and Elec. Engr., Morro Velho, Villa Nova de Lima, Honorio Becalho Minas Geraes, Brazil, So. America.

Jan 10, 1913

By Warren E. Wilson

The transportation of solids in pipe lines is a matter of deep concern in many fields of engineering. Much experimental and theoretical work has been done in an effort to devise means of designing pipe lines that will satisfactorily transport given solid loads, but there remain many unanswered questions in this field. The present discussion will be confined to a rather narrow portion of this field and will endeavor to point out certain factors that may well be considered when comparing the relative economy of various installations. The data have been presented previously but a new interpretation was prompted by a suggestion in a paper by Professor O'Brien,' of the University of California, that the friction work per pound of dry material should be considered in determining the relative efficiency of various installations. This method of considering relative economy in various pipe lines leads to some rather unexpected conclusions, especially with reference to the economy of large pipe sizes. A previous suggestion by the writer concerning the economy of a rather peculiar type of installation is strengthened. It is not believed that the considerations set forth herein apply directly in the case of dredge lines, where economy is largely a matter of a high rate of pumping in order to reduce the unit overhead charge. However, it is believed that some value may be gained from these considerations in cases involving the disposal of a fixed amount of solids per unit time with a minimum expenditure of energy and at a low cost for replacement of worn pipes. Such situations are not uncommon in the disposal of mill tailings and the disposal of solids deposited from irrigation waters. It was found that data leading to general conclusions for various pipe sizes were not available but certain definite trends are indicated and methods of analyzing available data are presented in the hope that they may be of assistance in preparing engineering estimates on designs of pipe lines of the type described above. Energy Requirements Carrying out the idea contained in Professor O'Brien's paper concerning the method of computing energy required to transport solids, the following analysis leads to some rather interesting conclusions. Let us represent: Solids load in terms of mass per unit time by w Ratio of mass of suspended solids to total mass of mixture flowing by p Volume rate of flow of mixture by Q Length of pipe by L Slope of energy grade line by s Mass per unit volume of solids by m8. Mass per unit volume of liquid by mi Mass per unit volume of mixture by 11 We then have as an expression for the solids load: w = pqmm The work done per unit mass, p, on the mixture to move it along the pipe the

Jan 1, 1947

By Warren E. Wilson

The transportation of solids in pipe lines is a matter of deep concern in many fields of engineering. Much experimental and theoretical work has been done in an effort to devise means of designing pipe lines that will satisfactorily transport given solid loads, but there remain many unanswered questions in this field. The present discussion will be confined to a rather narrow portion of this field and will endeavor to point out certain factors that may well be considered when comparing the relative economy of various installations. The data have been presented previously but a new interpretation was prompted by a suggestion in a paper by Professor O'Brien,' of the University of California, that the friction work per pound of dry material should be considered in determining the relative efficiency of various installations. This method of considering relative economy in various pipe lines leads to some rather unexpected conclusions, especially with reference to the economy of large pipe sizes. A previous suggestion by the writer concerning the economy of a rather peculiar type of installation is strengthened. It is not believed that the considerations set forth herein apply directly in the case of dredge lines, where economy is largely a matter of a high rate of pumping in order to reduce the unit overhead charge. However, it is believed that some value may be gained from these considerations in cases involving the disposal of a fixed amount of solids per unit time with a minimum expenditure of energy and at a low cost for replacement of worn pipes. Such situations are not uncommon in the disposal of mill tailings and the disposal of solids deposited from irrigation waters. It was found that data leading to general conclusions for various pipe sizes were not available but certain definite trends are indicated and methods of analyzing available data are presented in the hope that they may be of assistance in preparing engineering estimates on designs of pipe lines of the type described above. Energy Requirements Carrying out the idea contained in Professor O'Brien's paper concerning the method of computing energy required to transport solids, the following analysis leads to some rather interesting conclusions. Let us represent: Solids load in terms of mass per unit time by w Ratio of mass of suspended solids to total mass of mixture flowing by p Volume rate of flow of mixture by Q Length of pipe by L Slope of energy grade line by s Mass per unit volume of solids by m8. Mass per unit volume of liquid by mi Mass per unit volume of mixture by 11 We then have as an expression for the solids load: w = pqmm The work done per unit mass, p, on the mixture to move it along the pipe the

Jan 1, 1947

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

By streaming potential techniques, the zeta potential of quartz has been measured as a function of the concentration of dodecylammonium salts at different pH values. These experiments indicate that adsorption of dodecylammonium ions takes place as individual aminium ions until a certain critical concentration is reached in the double layer, at which point the adsorbed collector ions begin to associate into patches of ions, called hemimicelles. Because of its effect on the surface potential of quartz, pH controls the adsorption of dodecylummonium ions. The value of cooperating agents and nonionized constituents of flotation systems is discussed. Previous investigation of the role of pH in the flotation of quartz with anionic collectors is here extended to an inquiry of how the cationic collector, dodecylammonium acetate, is adsorbed at the quartz-solution interface. The equilibrium amount of this collector adsorbed by quartz has already been measured as a function of concentration and pH. The weight of prior evidence has suggested that two mechanisms are involved in the adsorption of this collector by quartz, but with existing adsorption measurements alone it is not

Oct 1, 1955

By R. C. Himes, K. Zanio, J. B. Wagner, J. W. Moody, J. F. Miller, W. Johnson

The recent research with which this paper deals has been concerned with the preparation of pure PbTe crystals suitable for control of radiative processes and othe.v electronic applications. The research has been directed toward the developrnent of methods for the preparation of puve, homogeneous, loul-ca,wier-density PbTe crystals suitable for use in the fabrication of optically pumped and electrically pumped diode lasers. Steps in the preparation of the crystals include 1) purification of the starting materials, 2) synthesis and purification of the PbTe, 3) growoth of PbTe crystals, and 4) adjustt~zertt of composition of the crystals This Paper describes the general preparation procedure employed and discusses some investigntiotzs of purification processes. THE as-received lead and tellurium are nominally 99.999 to 99.9999 pct pure. Assays furnished by the suppliers, obtained by emission spectrographic analysis, show only the presence of about 2 ppm Mg in the tellurium. Such analyses are not very informative, however, since they give no information on the concentrations of normally gaseous impurity elements such as oxygen. Both the lead and the tellurium in the as-received state usually contain appreciable concentrations of oxygen—primarily in the form of oxides on the surfaces of the material. To reduce the oxygen content, the lead is held in the molten state in hydrogen at -700°C for several hours. For this treatment, the lead is contained in a graphite boat which is rf-heated, and the hydrogen is passed through a liquid-nitrogen trap prior to use. Tellurium is subjected to multiple distillation in hydrogen to remove oxygen and other foreign impurities. If, in conducting the distillation, approximately the last 10 pct of the charge at each "stage" is left as the discard cut, purification of the tellurium proceeds as indicated in Fig. 1.l Tellurium used in this work has been distilled two or three times to reduce carrier concentration to about 10" per cu cm. The PbTe is prepared from the purified elements by reacting them in the molten state in sealed, evacuated, or hydrogen-filled silica ampoules. The charge is usually held above the melting point of PbTe (923°C) at 1000 C for 24 hr to ensure that it has been homogenized. Two methods have been employed for the growth of the required single crystals of PbTe: growth from the melt, which will be discussed first, and growth from the vapor phase. Large single crystals of p-type PbTe can be grown readily from the melt by the Bridgman method. For this method of crystal growth, the PbTe is synthesized in situ from proper proportions of the purified elements. Growth (dropping) rates in the range 1.3 to 6.5 mm per hr are employed. Material near the maximum melting composition (about 50.012 at. pct Te) is utilized to avoid composition change on freezing, and thus to obtain crystals of nearly uniform composition. Crystals prepared by use of procedures described up to this point were sufficiently pure and perfect that they could be used for the preparation of laser crystals in studies at Lincoln Laboratory.2-5 ADJUSTMENT OF COMPOSITION Good n-type crystals of PbTe cannot readily be grown from the melt. Further, growth from the melt of crystals of any compositions (n or p type) other than those near the maximum melting composition is difficult because of the large composition changes that must occur on freezing.'" However, melt-grown crystals can rapidly be brought to other desired compositions by isothermal equilibration through the vapor phase with a two-phase Pb-Te stock material, essentially as described by Brebrick and Allgaier.1 The work to be discussed has been concerned with the preparation of n-type crystals; thus, the two-phase stock which was employed contained excess lead, and all ensuing discussion is of the preparation and properties of n-type crystals. The equilibration was designed to the shift composition to the lead-rich limit of stability at the selected temperature. Initial treatment of the crystals at high temperature was employed to minimize the total time required for the equilibration. Final adjustments of the composition and state of the crystals were made by use of low-temperature heat treatment at temperatures in the range 200" to

Jan 1, 1968

By Coolbaugh, Franklin

CRUSHING of Climax mine-run ore is carried out in two plants: No. 1 plant (flowsheet in Fig. 1) has a capacity of approximately 5000 tons per day. It is used as a stand-by except when maximum production is required. No. 2 plant (Fig. 2) has a top capacity of approximately 17,000 tons per day. The No. 2 crusher is more efficient to operate on reduced tonnages regardless of the wide variation in peak capacities. The system of crushing is similar in both plants: Mine ore, of a size which can be drawn through 48 by 96-in. slusher openings underground, is dumped into the crusher bins from ten-ton mine cars and fed into 48 by 60-in. Buchanan jaw crushers by means of chutes and Ross chain feeders. The jaw crushers are set to discharge at approximately 9-in. size. Jaw crusher discharge is conveyed to 7-ft. Symons standard cone crushers where it is broken to minus-2-in. size,

Jan 1, 1946

Duval Corporation, the owners of the Sierrita, Esperanza, and Mineral Park copper operations in Arizona, first acquired the mineral rights to their Battle Mountain, Lander County, Nevada, property in 1962. Development of the mine commenced in mid - 1965, and the copper operation began at the end of 1968. The ore, a mixture of chalcocite and chalcopyrite, was milled and floated at a rate of 3, 175 mtpd (3,500 stpd). Because of low copper grade and price, the plant was shut down after about ten years of operation. Attention was then turned to an adjacent low-grade precious metal ore body which contained 2.74 g Au and 3.4 g Ag per mt (0.08 oz Au and 0.10 oz Ag) and minor amounts of copper. Test work revealed recovery by Carbon-In- Pulp treatment would amount to approximately 2.8 mt (90,000 oz) each of gold and silver per year. A rapid engineering and construction schedule resulted in the world's largest, as of late 1980, Carbon-In- Pulp plant being put on-stream in January 1979, with a capacity of 2.720 mtpd (3,000 stpd). Fortunately, the original crushing and grinding plant with all its infra structure was available, and the only modification needed was the addition of a gravity circuit to remove coarse free gold ahead of Carbon- In-Pulp treatment. One of the four primary 500 mm (20 in.) cyclone underflows in the primary ball mill circuit is directed to a secondary ball mill where its product is again cycloned. The cyclone underflow is screened at 3,360 microns (6 mesh) with the undersize being treated on two Pan American 1.07 m by 2. 14 m (42 in. by 84 in.) jigs. Hutch product is further concentrated on two Wilfley tables, a magnetic separator, and on a third Wilfley table where approximately 930 g (30 oz) of gold are recovered each day for amalgamation, retorting, and smelting. Returning to the grinding circuit, the final cyclone overflow is sent to the original plant tailings thickener to obtain proper pulp density for Carbon-In-Pulp treatment. Thickener underflow, at about 40% solids, is then conditioned with air and lime in a series of two 8.5 m by 9.75 m (28 ft by 32 ft) 15O cone bottom Pachucas for oxidation of pyrrhotite. The pulp is then split into two streams for cyanidation for 48 hours in two lines of eight Pachucas of the same size. Pulp is transferred from tank to tank by auxiliary air lifts. Cyanided pulp is then sent to a series of six C. I. P. mechanically agitated tanks with one hour retention in each tank. Originally these

Jan 1, 1981

By Eckhard Nembach

The phase diagram of the system Pb-In has been investigated between -27° and + 40°C, using nzainly X-ray dijfraction. In accordance with t her mo dynamic measurements by Heumann and Predel, a segregation occurs at low temperatures, though not in the form of a nziscibility gap. THE phase diagram of the system Pb-In has been the subject of extensive investigations,1&apos;1 but recently Heumann and prede13 concluded from their thermodynamic data that a new feature should occur below room temperature. These authors observed that the maximum values for the enthalpy and entropy of mixing, which occurred at a composition of 50 at. pct Pb, were +400 and —1.7 cal per g-atom deg, respectively. From this the authors estimated that a miscibility gap should occur below 30°C, centered at 50 at. pct Pb. Resistivity measurements seemed to support this view. These authors proposed the phase diagram outlined in Fig. 1. Three phases exist at 30°C: the tetragonal indium phase with c/a > 1, the tetragonal intermediate phase a, with c/a < 1, and the fcc lead phase. During an investigation of the superconducting properties of Pb-In alloys. it has been observed4 that aging a specimen with 50 at. pct Pb for 14 days at -18°C decreased the superconducting transition temperature about 0.13"K and tripled the transition width. In this paper, the results of an investigation of the Pb-In phase diagram in the temperature range from — 2T to +40°C are reported. Superconductivity and X-ray methods have been used. 1) SPECIMEN PREPARATION The materials were provided by the American Smelting and Refining Co. According to the manufacturer their purity was 99.999 pct. The weighed amounts of the constituents were sealed in quartz tubes under an atmosphere of 10 torr helium, mixed for 24 hr in a rocking furnace at 380°C, quenched in ice water, and homogenized at 20" to 30°C below the solidus line, established by Heumann and Predel. The annealing times were 144 hr for specimens containing Less than 30 at. pct Pb and 36 hr for the remainder. 2) SUPERCONDUCTIVITY EXPERIMENTS The specimens were quenched from the homogeniza-tion treatment into ice water and their superconducting transition temperatures T, measured. The procedure used has been described in Ref. 4. The transition was detected by the change of the mutual induc- tance of two coaxial coils containing the sample. T, was defined as the temperature at which 50 pct of the total change in inductance had occurred. The repro-ducibility with which T, could be measured was i0.002"K. Then the specimens with lead contents between 38 and 75 at. pct were aged for 7 days at temperatures between -30" and 40°C. If this treatment caused T, to change by more than 0.005"K or the width of the transition to increase by more than 0.002"K, it was concluded that the specimen had undergone a phase change and no longer consisted only of the fcc lead phase: as it did immediately after homogenizing. The result is shown in Fig. 2. From this one can estimate at what temperatures and concentrations phase changes occur. The X-ray measurements were based on these preliminary results. 3) X-RAY EXPERIMENTS Because of the softness of the material, relatively coarse powders. 75 p, had to be used, which were filed in a helium atmosphere from homogenized specimens. The powders were annealed at least 30 min at temperatures between 120" and 16OJC, depending on their concentration, and quenched in ice water. Then their X-ray patterns were taken at -178°C with a Picker diffractometer, model 3488K, and a cold stage. on which the specimen was in thermal contact with a liquid-nitrogen reservoir. In this way the following relation was established for the fcc lead phase: a = 4.697 + 0.00247C for 40 5 C 5 75 11 where n is the lattice constant (A) and C is the at. pct of lead. The coarseness of the powder made it impossible to use lines with 0 > 75 deg; therefore n was averaged from lines with 45 deg 5 0 5 75 deg. The results were reproducible to within i0.05 pct. Relation [I] is very similar to the one found by Heumann and Predel at room temperature. Following this, homogenized specimens with compositions between 15 and 56 at. pct Pb were aged for at least 10 days at temperatures between -27" and

Jan 1, 1970

By R. A. Garling

INTRODUCTION Since the infancy of in situ uranium mining, a growing number of hydrometallurgical processes have been incorporated into pilot and commercial scale flowsheets. Although initial design efforts were geared toward maximizing uranium recovery and minimizing plant and wellfield flow circuit maintenance, recent emphasis has shifted to improved means of water conservation and aquifer restoration. As mining units approached depletion, evaporation ponds reached minimum freeboard, and state and federal agencies demanded proof of groundwater restoration, processes including mixed bed and conventional ion exchange, reverse osmosis and electrodialysis were adopted by the industry. These units served the additional function of reducing process bleed flows during mining in states where the deep disposal well permitting ice remains unbroken. This report concerns the use of electrodialysis as an alternative to the more conventional processes used in in situ mining. In addition to a brief history and description of the process, a comparison to reverse osmosis and operational data derived from testing an Ionics, Inc. 1.31 x 10-3 m /s (30,000 gallon/day) unit at the Teton-Nedco Leuenberger Research and Development pilot will be presented. HISTORY Commercially practicable electrodialysis was contingent upon the development of synthetic ion exchange membranes in 1940&apos;s. In 1952, Ionics Inc. demonstrated that the process was amenable to the treatment of salt and brackish water and, in 1954, made their first commercial sale. The following decade saw several major electrodialysis unit sales which were generally targeted for use on private or municipal potable water treatment. Major increases in membrane desalting unit capacities, facilitated by technological advances in the reserve osmosis industry, were noted during the 1970&apos;s. The development of polarity reversing electrodialysis equipment which reduced feed pretreatment requirements, increased water recovery rates, and simplified unit operation, kept Ionics Inc. competetive in the water treatment industry. Engineering advances which incorporated automated equipment, non-corrosive construction materials, and improved ion exchange membranes allowed the electrodialysis process to compete in industrial waste treatment among other commercial markets. PROCESS AND APPARATUS DESCRIPTION The electrodialysis process utilizes direct electrical current passed across a stack of alternating cation and anion selective membranes in order to achieve an electrochemical separation of ionized materials in an aqueous solution. The membrane stack has the appearance of a plate and frame filter press and auxilliary equipment includes solution pumps, electrically actuated valves, filters, piping and a direct current power source. The ion separation membranes are thin sheets of synthetic cation or anion selective resins. Attaching sulfonate or quaternary ammonium groups to the cross linked copolymer structure determines the ion selectivity of the membrane. The membranes are separated from each other in the stack by non-conductive spacers that house flow channels which route the flow tortuously and parallel to the membranes. Direct electrical current passing perpendicularly to the membranes and solution passages attracts cations toward the cathode and anions toward the anode (Figure 1). As the ions from the feed stream pass through the ion selective membranes, they become concentrated in the adjacent brine channel and are retained there by the combined attractive force of the electrode and the repelling force of the next membrane toward the electrode. Limiting factors on the degree of demineralization possible include chemical solubilities in the brine flow and the current density that will produce an unacceptable degree of polarization (Figure 1). Feed or brine solution treatment with complexing agents or acids has been successfully applied to prevent membrane scaling. Polarization can occur when sufficient current density is applied to dissociate water in the ion depleted region of the diluting compartments near the membrane surfaces. Significant polarization is evidenced by large electrical resistances across cell pairs and notable pH differences between diluting and concentrating streams. Limiting current densities have been increased in U.S. manufactured equipment by utilizing tortuous flow paths of relatively high linear velocities thereby promoting continous solution mixing. Energy consumption is due to separating electrolytes and solutions, oxidation and reduction reactions occurring in electrode compartments, overcoming electrical resistance, conversion from AC to DC power, solution pumping and auxiliary equipment actuation. A major improvement to the basic electrodialysis process was applied in 1970 which resulted in frequent, automatic cleaning and descaling of membrane surfaces. The process, polarity reversal, incorporates alternating the cathode and anode on a periodic basis while exchanging product and brine flow channels via electrically actuated values. The reversal reduces the potential of stack plugging with CaCO3 (calcite), CaSO4 (gypsum), and colloidal materials and, in most waters, eliminates feed pre-treatment requirements. For approximately two minutes during and following the reversal, off spec. water is flushed to waste or reintroduced to the feed supply. The usual feed treatment on polarity reversing electro-

Jan 1, 1982