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By Donald W. Scott

This paper describes the application of ore-dressing methods to the reclamation of milled frit from over-spray, or waste, porcelain enamel. Frit is the name given by enamelers to a granulated glass produced by the smelting and subsequent water quenching of various ingredients capable of forming a glass, usually including a compound to produce opacity. It is the major component of porcelain enamel, and normally commands a price ranging from 7 to 12 cents a pound. In the *preparation of a white enamel slip, usually 6 or 7 parts of clay, 2 parts of opacifier, small amounts of electrolytes, in some cases inorganic color stabilizeis and organic dyes, and 35 parts of water are added to 100 parts of frit; the mixture then is milled to a fineness of the order of 92 to 95 pct through a 200-mesh sieve. The frit forms the base of the enamel; the opacifier imparts opacity or reflectance; the clay suspends the frit while in slip form and serves as a binder in bisque form (dry and unfired); and the electrolytes control the workability. Spraying is used commercially, in many cases, to apply the finish coat of enamel to the ware, prior to drying and firing. In the spraying operation, only about 50 pct, by dry weight, of the enamel slip adheres to the surface of the ware, the remainder forms the over-spray. From 1/2 to 2/3 of the overspray goes up the flue where it is lost or recovered, depending on whether the plant is equipped with a dust-collecting installation; the coarser portion of the over-spray is collected in the spray booth. The former product is termed flue reclaim enamel, and the latter booth reclaim enamel. Although the spraying operation is done in specially constructed booths, which are partially or completely enclosed, it is extremely difficult to keep out contaminating dirt, which joins the reclaim. Some present-day large enameling plants use 20 tons of frit a day, of which 10 tons go into reclaim with a potential value of $1400 to $2400. When two-coat finish enamels were common, the reclaim was used satisfactorily for the undercoat, but the relatively recent advent of one-coat finish enamels prevented use of the reclaim because, even when blended with first-run enamels, it gave dirty finishes with poor gloss. It was thought that the pitting and specking encountered with reclaimed enamels were caused by the contaminating dirt, and that the poor gloss was caused, primarily, by the high clay content; more clay usually was added to give proper suspension properties to the slip when the reclaim was used. A clay content in excess of about 10 pct usually imparted refractoriness to porcelain enamels. Present-day one-coat porcelain enamels must combine high gloss and opacity with freedom from surface defects. Methods of beneficiating the over-spray,

Jan 1, 1948

By D. A. Dahlstrom

Although the liquid-solid cyclone is a relatively recent innovation in the field of coal preparation, various authors have already indicated three distinct applications to operations encountered in the modern tipple. Driessen's articles and work at the Dutch State Mines exhibited its possibilities in the beneficiation of fine coal with apparently high efficiencies down to the 200-mesh fraction. 1 2 3 4 Other publications point out its use as a recoverer, thickener, and preliminary dewatering agent of fine coal which in too many cases is being wasted due largely to former high operating cost limitations 5 6. Finally, certain authors have emphasized the practicability of applying the cyclone to the elimination of coarse and fine solids from water slurries in the tipple in order to produce a water suitable for recycle purposes containing only minute particles far below the 200-mesh size.6 This would result in a closed water system for many cases, with its accompanying economic and operating advantages to locations where water quantity and quality problems are severe; better operation of washing equipment using a consistent water devoid of injurious fine particles; lowered maintenance costs due to the lesser abrasion resulting when the fine abraiding particles are removed; and the greater ease of disposing of refuse streams of reduced volume containing greater percentages of solids.

Jan 1, 1949

By C. R. Ramachandra, C. C. Patel

Flotation of chalcopyrite from a low grade ore was studied by using different xanthates and dixanthogens as collectors and by conditioning the flotation pulp with oxidizing gaseous systems. The improvement in the recovery of chalcopyrite with the oxidizing systems was mainly due to the auto-activation of chalcopyrite, leading to the enhanced adsorption of xanthates and dixanthogens even when the latter were formed by oxidation of the xanthates. With air or oxygen as oxidizing system, the amount of ethyl xanthate required at pH 8.5 was much less than normally employed in the industry, the recovery being 97-99% of chalcopyrite with a concentrate of 24% copper. With isopropyl and isoamyl xanthates, the recovery was improved but the grade was lowered. By conditioning the pulp with air-CO2 or oxygen-CO2 mixture, the recovery was lowered with ethyl xanthate only, mainly due to the depressant action of bicarbonate formed. Flotation with dixanthogens gave cleaner concentrates of chalcopyrite. because iron pyrite did not float with these collectors. Of the dixanthogens tried, diisopropyl dixanthogen gave the highest recovery, 99% chalcopyrite with a concentrate containing 28.5 to 30% copper, when the pulp at pH 8.5 was condi-tioned with air. Isopropyl dixanthogen was found to be the best collector of all the xanthates and dixanthogens studied. It was found that the adsorbed ethyl, isopropyl and isoamyl xanthates at chalcopyrite surface, activated by cupric sulfate, and at iron pyrite surface were oxidized to the corresponding dixanthogens to different degrees in presence of air, oxygen, air-carbon dioxide mixture and oxygen-carbon dioxide mixture.' The dixanthogen formed at chalcopyrite surface was, however, firmly adsorbed while that at iron pyrite surface was easily desorbed. Since dixanthogens formed have greater hydrophobicity than the corresponding xanthates, as revealed by contact angles,1,2 the former were expected to improve the flotation results. It was, therefore, thought desirable to find out the effect of air, oxygen, air-carbon dioxide mixture and oxygen-carbon dioxide mixture on the selective flotation of chalcopyrite when individual xanthates were used as collectors. The effect of direct use of dixanthogens as collectors on the selective flotation of chalcopyrite was also investigated. For these studies, low grade chalcopyrite ore, received from the Indian Copper Corp., Ltd. (I.C.C.), Ghatsila, Bihar, was employed. At the milling plant of the I.C.C., chalcopyrite is floated at a pH of 8.5, employing ethyl xanthate as collector. EXPERIMENTAL Materials Employed: XANTHATES - Ethyl, isopropyl and isoamyl xanthates of potassium were prepared in a pure state by the methods described earlier.4 A 0.03% aqueous solution of a xanthate was freshly prepared in air-free distilled water for flotation studies. DIXANTHOGENS - Diethyl, diisopropyl and diisoamyl dixanthogens were prepared by the oxidation of xanthates by iodine and purified by extraction with petroleum ether. A 0.03% alcoholic solution of dixanthogen was used as a collector. FROTHER - A 0.2% solution of pine oil in ethyl alcohol was employed. SODIUM CARBONATE - A 0.4 N solution was used. ORE - The composition of the -100 +200-mesh size (Tyler standard) powdered ore, as determined by standard methods of analysis, was: copper 1.57%, iron 10.29%, sulfur 3.15% and acid insolubles 66.10%. Iron present as chalcopyrite (CuFeS2) was 1.38%, while that present as iron pyrite (FeS,) was 1.37%. Both chalcopyrite and iron pyrite were found to be liberated from the gangue minerals and from each other, as observed under a microscope. Flotation of Chalcopyrite with Xanthates in Presence of Different Gaseous Systems: Fifteen grams of -100 + 200-mesh size ore were shaken well with 100 ml of distilled water. The pH of the pulp was adjusted to 8.5 by the addition of sodium carbonate solution. Then 0.1 ml of xanthate solution (0.005 lb xanthate per ton of the ore) was mixed with the pulp, and the latter together with washings transferred to a

Jan 1, 1963

By M. J. Duggin

Structural similarities between the E, X, and iron carbides are illustrated. Experimental evidence regarding phase transformations occurring during ternpering reactions in finely divided carbides, thin-film carbides, and carbides which occur in steels is considered and possible mechanisms for the E — x and x — 9 transformations proposed. HOFER1 has shown that within the appropriate temperature ranges carbon monoxide will react with finely divided a iron to form either iron carbide or x iron carbide. He has shown that at an elevated temperature the E iron carbide will transform to the x iron carbide (Hagg carbide) which, upon further elevation of temperature, will transform to 9 iron carbide (cementite). Jack,2,3 using X-ray diffraction methods, has observed that during the tempering reactions occurring in steel the E iron carbide formed in the first stage of tempering passes into two-dimensional platelets of 0 iron carbide during the second stage of tempering. The three-dimensional form of the 0 carbide is formed during the third stage of tempering. Jack suggested2 that the two-dimensional platelets of 0 carbide could be related to the faulted x iron carbide. Okada and Arata4 investigated a Swedish steel containing 1.05 wt pct C and approximately 1.0 wt pct Mn using permeability measurements at low field strength. A Curie point of 360°C was observed in the quenched steel, which indicated the presence of E iron carbide. On tempering at 400°C the specimen developed a Curie point at 230°C, indicating the presence of x iron carbide, and on tempering at 700°C the specimen developed a Curie point at 190°C which was assigned to 0 iron carbide. The carbides were extracted electro-lytically and the use of X-ray diffraction techniques4r5 indicated the carbide with a Curie point of 230°C to be x iron carbide. The Curie points of the carbides are 10 to 22°C lower than the accepted values which is probably due to the presence of manganese in the carbides, since it has often been observed (e.g., Ref, 6) that a partial substitution of manganese for iron in cementite will lower the Curie point of this carbide. Hofer' summarizes additional evidence of the tempering reactions in steel in which E iron carbide, formed during the first stage of tempering, transforms to x iron carbide during the second stage of tempering. During the third stage of tempering, the x carbide disappears as the 0 carbide is formed. By carburizing thin iron films in a CO gas stream, ~a~akura' has been able to produce the E, X, and 0 iron carbides. He found that below 250°C the E iron carbide was formed; between 250" and 350°C the x iron carbide was formed and above 350°C the 0 iron carbide was formed. He has shown that the E iron carbide transforms to form x iron carbide at 380" to 400°C and that the x ir°n carbide transforms to form the 0 iron carbide at approximately 550" C; both of these phase transformations are irreversible. Hofer' presents a review of evidence to show that the sequence of reactions occurring during tempering processes subsequent to the formation of E iron carbide formed by the direct carburization of finely divided a iron is the same as the sequence of reactions which occur during the tempering processes subsequent to the formation of E iron carbide in steel during the first stage of tempering. It is evident from Nagakura's work that identical tempering reactions are found in thin films of iron which have been carburized to form iron carbide. The purpose of this paper is to discuss the structural similarities between the E, X, and 0 carbides and to suggest a possible mechanism by which regions of the E carbide, formed during the first stage of tempering, may transform to the x carbide during the second stage of tempering. For the finely divided or thin film carbides a mechanism will be proposed for the transformation of the x carbide to the 0 carbide during the third stage of tempering, although it will be suggested that there is evidence that such a transformation may not occur in steels. STRUCTURAL DATA OF THE E, X, AND 0 IRON CARBIDES € Iron Carbide. It is evident from X-ray diffractions and electron diffraction', investigations that the metal atoms in the E iron carbide form an hcp structure with lattice constants ah = 2.752A, ch = 4.3534, using electron diffraction, reports the lattice paramet$rs of the superlattice cell to be a = 4.767A, c = 4.354, c/a = 0.9134. He finds that the carbon atoms occupy the octahedral voids in the metal atom structure so as to form a hexagonal stacking sequence with its basal plane parallel to that of the metal atoms. Considerable long-range disorder occurs in the positioning of the carbon atoms, however, which is in agreement with the possible range of composition Fe2C-Fe3C discussed by Hofer.' Barton and ale" have made X-ray diffraction measurements on a sample of E iron carbide extracted from a catalyst in an organic process. Although there were few reflections recorded on the obtained X-ray powder diffraction pattern, they have proposed that the structure could belong to one of the three possible space groups p3m1, P63/mmc, or Pbcn if one assumed the composition to be Fe2C. Nagakura, using electron diffraction data, suggests a space group of P 6322 for a specimen of c iron carbide of apparent composition Fez.&. x Iron Carbide. The x iron carbide has been studied by Duggin and Hofer" and by Jack and wild,' who

Jan 1, 1969

By AIME AIME

IN A STATEMENT summarizing general conditions in the Federated American Engineering Societies, the executive secretary, L. W. Wallace, expresses the belief that the Federation has made substantial progress. At the annual meeting of the American Engineering Council, to be held in Washington Jan. 5 and 6, this progress will be shown by reports covering activities in many fields. "Unquestionably," says Mr. Wallace, "the Federa¬tion has made favorable and permanent contacts in Washington. Through the, activities of Congress and of the new Federal administration. we have had the opportunity to render some really constructive service. We feel, however, that the great body of engineers are not adequately informed of the organization of the Federation, of its aims and purposes and of its activities.

Jan 1, 1921

By H. S. Martin

Although it was known some years ago at the Utah Copper Co. mills that fine grinding improved flotation recoveries, no accurate data were available until recently as to just how far the grinding could be carried economically. In 1923 the ultimate degree of fineness for flotation feed was supposed to be about 10 per cent. on 65 mesh, with approximately 55 per cent. through 200 mesh, which meant that most of the mineral would pass 100 mesh. At this time Garfield and Wilfley tables were used ahead of flotation and a good deal of the coarse mineral removed prior to the ball mill regrind. Shortly afterwards, mill-scale tests developed the fact that on a feed containing not over 10 per cent. +65-mesh material flotation alone would give a copper recovery equal to that obtained by the combination of tables and flotation, but that on much coarser feed the recovery with flotation alone was lowered. This was at a time when all the sulfide minerals were floated if possible, so that the only requisite was to grind fine enough to free the mineral from gangue. Earliest Use of Microscopic Examination of Tailings As early as 1921, the writer had attempted to determine by chemical analysis the relative proportions of copper minerals in tailings from an ore that made extremely poor flotation results. Chemical analysis was not satisfactory or conclusive, and samples of these tailings were sent to the U. S. Bureau of Mines Station at the University of Utah for microscopic examination. The question at that time was to determine, if possible, which copper minerals had been lost and why, but R. E. Head, in his report, revealed other interesting data. He said in part: Briefly stated, the mineral partieles or grains may be classified into scparate groups as follows: 1. Free grains of pyrite, chalcopyrite, chalcocite and bornite, respectively, which contain 110 other included sulfides; 2. Grains in which all three of the copper sulfides are representel (the core may be of chalcopyrite, partially altered to boruite, these two minerals being cntirely surrounded by a shell of chalcocite); 3. Grains composed of equal amounts of bornite and chalcocite or chalcopyrite and chalcocite. The grains of free mineral particles are perhaps the most numerous, taking the ore as a whole, but it is noticeable that of the grains of combined or associated sulfides

Jan 1, 1930

New York Meets first Wednesday after first Tuesday of each month. W. FRANCIS, Chairman, WILLARD S. MORSE, Vice-Chairman. THOMAS T. READ, Secretary, Woolworth Bldg., New York, N. Y. P. A. MOSMAN, Treasurer. LOUIS D. HUNTOON. WILLIAM A. POMEROY. Boston Meets first Monday of each winter month. HENRY L. SMYTH, Chairman. ALFRED C. LANE, Vice-Chairman AUGUSTUS H. EUSTIS, Secretary-Treasurer, 131 State St., Boston, Mass. ROBERT H. RICHARDS, ALBERT SAUVEUR. Columbia FRANK A. ROSS Chairman. RUSH J. WHITE, Vice-Chairman. LYNDON K. ARMSTRONG, Secretary-Treasurer, P. O. Drawer 2154, Spokane, Wash. FREDERIC KEFFER, FRANCIS A.,THOMSON.

Jan 4, 1915

THE hall of the Western Iron and Nail Associations having kindly been placed at the service of the Institute, the opening session was held at 3 o'clock, Tuesday afternoon, May 13th, with an attendance of about one hundred and twenty-five members. Mr. William Metcalf, of Pittsburgh, read an address of welcome on behalf of the Local Committee of Arrangements, to which President E. B. Coxe responded. The following papers were then read and discussed : Regenerative Stoves; a Sketch of their History and Notes on their Use, by John M. Hartman, of Philadelphia. Some Curious Phenomena Observed on Making a Test of a Piece of Bessemer Steel, by William Kent, of Pittsburgh. On the Use of Determining Slag Densities in Smelting, by Thomas Macfarlane, of Wyandotte, Michigan. After the reading of these papers each member was presented by the Local Committee with a schedule of excursions, a specially prepared map of Pittsburgh and surroundings, and a directory of industrial works, all tastefully bound, and also with a metal badge bearing the seal of the Institute, to be worn on the excursions. The second session was held on Tuesday evening. The following persons, duly proposed for members and associates of the Institute, were, on the recommendation of the Council, unan¬imously elected. (In this list are included those elected at the final session on Friday morning.) George Bartol, - Cleveland, Ohio. Luther S. Bent, - Steelton, Dauphin Co., Pa. Octave Chanute, - New York City. Albert H. Childs, - Allegheny, Pa. Theodore Cooper, - New York City. Andrew Cosgriff, - Brewster, Putnam Co., N. Y. William B. Crocker, - New York City. Henry M. Curry, - Pittsburgh, Pa. Charles Davis, - Allegheny, Pa. Henry F. De Bardeleben, - Birmingham, Ala. Herbert Du Puy, - Pittsburgh, Pa. Charles L. Fitzhugh, - Pittsburgh, Pa. W. S. Franklin, - Ashland, Md. F. G. Fricke, - Pittsburgh, Pa. Paul A. Fusz, - St. Louis, Mo. Ignatius Hahn, . Pittsburgh, Pa. Henry Hargreaves, - South Pittsburgh, Tenn.

Jan 1, 1880

By Arthur Smith

THE Verde mining district is in Yavapai County, in north-central Arizona. Jerome, the principal town, has a population of 6000 and the two important mines of the district-the United Verde and the United Verde Extension-lie almost within its limits. Perched high on the southwest side of the Verde valley, at elevations of 4800 and 5500 ft. (1463 and 1676 m.) respectively, both mines have long tunnels from their lower levels through which the ore is hauled to the smelters. Clarkdale, the smelter town for the United Verde mines, lies in the Verde valley 4.1 miles (6.5 km.) distant in an air line from Jerome and at an elevation of 3560 ft. The two towns are connected by the standard-gage railroad of the Verde Tunnel and Smelter R. R., a subsidiary of the United Verde Copper Co. This road is 11 miles long and has a compensated grade of 4 per cent. At Clarkdale it connects with the Verde valley branch of the Santa Fe railroad. Clemenceau, the smelter town for the United Verde Extension mine, lies 3.5 miles (5.8 km.) in a southeasterly direction from Clarkdale, at an elevation of 3420 ft. It is connected to the Verde Valley branch of the Santa Fe railroad at Clarkdale by the Arizona Extension R. R., . a subsidiary of the United Verde Extension Mining Co. The portal of the haulage tunnel, at an elevation of 3757.5 ft., is also connected with the smelter town by 4 miles of standard-gage track belonging to? the same company. In the vicinity of Jerome, the great southern escarpment of the Arizona plateau forms the northeast side of the Verde valley. The general level of this escarpment, or "rim" as it is called, is about 4000 ft. above the Verde River. A corresponding elevation is reached only by the highest peaks of the Black Hills, which bound the valley to the southwest. Two lava-capped mesas, known as "Mingus" and "Wood chute mountains," form the culmination of the Black Hills. That part of the Old Black Hills mining district which lies between their crests and the Verde River is now known as the Jerome, or Verde, mining district. If the . smelter towns are not included, a strip about 7 miles long by 3 miles (11 by 5 km.) wide, embraces practically all of the properties belonging to the Jerome district. This strip lies parallel to and along the side of the Verde valley from First View, 2 miles northwest from Jerome, to the vicinity of Allen Springs, at the south end of Mingus mountain and all within the boundaries of the Prescott national forest reserve.

Jan 3, 1924

By R. S. Craig, W. E. Wallace, G. S. Kamath

The destruction of long-range order in Mg-Cd, has previously been thought to occur as a second order process. In the present work a variety of X-ray diffraction techniques are employed to show that in this case and in Mg-Cd alloys containing frorn 20 to 33 1/3 at. pct Mg the process more nearly resembles an ordinary first order phase transformation. It is found that the ordered alloy, which occurs as a single phase at lgw temperatures, transforms with increasing temperature into a Cd-enriched disordered (P) phase and an Mg-enriched ordered (a) phase. The interval over which these two phases coexist under apparently equilibrium conditiovs extends from 25" to 87°C content. At 33 1/3 at. pct Mg the two-phase region has disappeared. Measurement of the long range order parameter, s, for the ordered phase in MgCd, (from superlattice line intensities) shows that it disorders only very slightly before it is transformed into the p form. Kinetic experiments reveal that when the a phase is formed frorn the p phase by suitably quenching so as to suppress phase segregation, the transformation is essentially complete and the a phase has acquired its equilibrium value of S in less than 1 min. In an earlier investigation carried out in this Laboratory1 the rate of disordering of the MgCd3 superlattice was determined over an extensive range of temperature. The process was found to be first order and the rate constant, k, was established. At the lowest temperatures studied k was found to increase exponentially with temperature. At higher temperatures, however, it passed through a maximum and for the 100 deg interval below the point at which the superlattice was destroyed k was observed to decrease with increasing temperature. The various theoretical treatments1-3 of order-disorder phenomena lead to a negative temperature coefficient for k near the superlattice critical temperature but this region for MgCdB seemed unusually wide. Detailed analysis of the point indicated' that either the long-range order parameter, S, for MgCda varied with temperature in an anomalous way or the disordering in this instance is more complex than in the cases which have been treated theoretically. The original objective in the present work was simply to determine S vs temperature for MgCda to ascertain whether the disordering was in conformity with theoretical expectations.2° In an early stage of the work it was noted, however, that under equilibrium conditions ordered (a) and disordered (0) phases coexist in MgCd, over a considerable range of temperature. Since on thermo- dynamic grounds the coexisting phases must differ in composition, the investigation was enlarged to permit the compositions of the two phases in MgCd3 to be determined and to establish the extent of the two phase regions for alloys containing from 20 to 33 1/3 at. pct Cd.

Jan 1, 1963

BETWEEN the third and twentieth days of November, 1903, six intensely interesting letters were mailed from Santiago, Chile, addressed to "Mr. William Braden, Consulting Mining Engineer, 71 Broadway, New York City." The subject of these communications, referred to as the "Rancagua mines," was a copper property situated in the high. Andes; and the writer was Marco Chiapponi, an Italian mining engineer. Many a letter has been written about potential mines and prospects, good and bad, situated in all parts of the world; but few of them combine the shrewdness, sincerity, naïveté, and salesmanship that appear in these fascinating letters by Chiapponi. In 1894, Mr. Braden, as a young man twenty-three years old, had gone to Santiago to look after the erection and operation of some mining machinery that was to be exhibited at the International Mining Exposition. Not the least important of his purposes was to get acquainted at first hand with the mines and mining men of Chile, which ranked at the time (as it does today) second to the United States as a copper-producing country. It happened that a dispute arose regarding charges for certain construction work done in connection with young Braden's exhibit. Finally, arbitration was agreed upon and the Chilean exposition officials proposed Se[n]or Marco Chiapponi as a fair-minded neutral to decide the question. This he did in a manner satisfactory to both sides, and subsequently he and Mr. Braden became good friends. Nine years later Braden wrote to Chiapponi inquiring as to certain matters connected with the Corocoro copper mines in Bolivia. It was to this letter that Chiapponi refers in his letter of November 3, from which the following are some extracts,

Jan 1, 1933

By Maurice Ewing

THE purpose of this paper is to present the results of the application of the earth-resistivity method of subsurface investigation to the problem of locating seams of anthracite coal beneath a mantle of soil and subsoil. Details are given of the successful use of this method in locating the outcrops of anthracite seams in actual prospecting. The presence of the outcrop of an anthracite seam is indicated at points where electrical resistivity tests showed relatively low readings. The reason for, this is that in some localities the resistivity of anthracite was found to be about 0.0001 megohm-cm. compared to 1 to 200 megohm-cm. for shales and sandstones. For two reasons it is believed that the data sum-marized in this paper should be of particular interest. In the first place, most of the interpretations of the resistivity survey have been checked by subsequent drilling and some by the removal of the overburden and the exposing of the anthracite seams. It is infrequent that the oppor-tunity for checking results so thoroughly is given. In the second place, the fact that recent commentators 1.2.1 on the application of geophysical methods to mining have concluded that direct prospecting for anthracite and other types of coal is not promising makes the good results obtained more significant. So far as the authors can learn, the only previous experiment with electrical methods in the Pennsylvania anthracite field was one made by Sherwin F. Kelly in 1922, when he used the self-potential method at Wilkes-Barre4. The profile he made does not show a very marked correlation with the geologic cross section. Kelly points out that stray currents from electric motors in the mines undoubtedly affected his results, but the experience of the present authors with stray currents from mining machinery suggests the possibility that the potentials measured by Kelly were due almost entirely to this effect.

Jan 1, 1936

By C. A. Heiland

The following summary is written for the benefit of the practical operator in the nonmetallic field who wishes to know what geophysics has done and may be expected to do in his line of work. His problem is quite different from that of the geophysicist who has operated with various or all methods and has followed the literature, and who is assumed to be familiar with the geologic possibilities and limitations of each method. This article is not written for the latter, although he may be interested in the four or five hitherto unpublished surveys described. To the operator, on the other hand, geophysics is only secondary. His problem is to determine which geophysical method is best suited to his special needs. If he wanted to know, however, which method could be used to locate a certain material of given physical properties, building stone, for instance, he would have to wade through a tremendous amount of geophysical literature, bibliographies and articles, before he could find what he wanted. Therefore, the purpose of this summary is to present the geological problems first and then to discuss the comparative merits of the geophysical methods that can be, or have been, applied. Choice of Geophysical Methods in Oil, Civil and Mining Engineering In the first two of these fields, the geological problems are not nearly so complex as in the metal and nonmetallic mining fields. The selection of the correct geophysical method in these fields is not nearly so difficult for the operator. For oil prospecting, his problems have been discussed exhaustively by E. DeGolyer.(1) † In civil engineering (foundation and ground-water work), the usefulness of electrical methods has been so well established that there is hardly any choice of other methods at present. The situation may be changed in the future with the perfection of the seismic reflection method for shallow depths. In the mining field the operator and often the geophysicist himself finds difficulty in determining which method is best suited for a given

Jan 1, 1934

By B. J. Shaw, R. Kossowsky, W. C. Johnston

High purity (99,95) Ni-51 wt pct cr eutectic alloy was unidirectionalty solidified at rates of 0.1 to 8 in. per hr. The resulting material was characterized by large grains, approximately 0.5 mm in cross section and extending through almost the entire length of the specimen, parallel to the growth axis. The eutectic structure of specimens the growth at -1/3 The per hr consisted of a continuous nickel-rich phase and chrome -rich lamellae approximately 2 thick, spaced about apart. Specimens were tested in compression at temperatures ranging from —196 to 850"C over which range the 0.2 pet yield strength dp -creased from 160,000 p si to 35,000psi, respectively. Swaging to 40 pet reduction in area, followed by a 30-min anneal at 1000c to remove residual cold work, increased the 0.2 pet yield to 260,000 psi at -196°C, dropping to 35,000 psi at 850°C. The increase in strength was attributed to a residual cell structure. The strength of the alloy could be rationalized by the simple rule of mixtures if one assumed that additional strength is derived front a size effect characterized by is petch equation IN recent years there has been increasing interest in dispersion and second phase strengthening in materials needed for high-temperature applications. inm role of structure on the mechanical The of such alloys has been well established of such some extent accounted for theoretically. and to of how the strengthening mechanisms due to fibers and lamellae operate has been reduced to its fibers form by the fabrication of composites of strong rods unidirectionally aligned in a From work on tungsten-fiber-reinforced copper, for example, it was established that the "Rule of Mixtures" could explain the strengthening.12 " some what more sophisticated technique for introducing strong fibers into copper matrix was used by Hertzberg strong Kraft3 who unidirectionally solidified the copper-chromium eutectic. The use of unidirectionally fied eutectics has advantages in that there are no matrix-fiber wetting problems and fine fibers are automatically aligned and uniformly fiber However, one Is restricted to a specific volume fraction of the second phase. Nevertheless, even though the volume fraction is fixed, the rod or lamella thickness, , can be varied by controlling the freezing interface velocity. Alternatively, the grown material may be worked down by swaging or rolling. Embury and Fisher, " using this approach, drew down pear lite in iron and studied the mechanical properties iron and that the yield strength, oy, was properties.proportional They that d was the wire diameter. It could be inferred that was also proportional to but the work hardening had to be taken into consideration at the same time. By varying the growth rate of the cadmium-zinc lamellar eutectic, Shaw'1 showed that was proportional to without the introduction of work hardening and suggested that the lamellar interface itself contributed to the strengthening of the composite. In this investigation we have evaluated the mechanical properties of the unidirectionally solidified fec-bec eutectic Ni-Cr. This eutectic was selected because it presented the possibility was selected beca temperature, and high corrosion resistant alloy, and also represented a hard-soft phase combination with two completely different slip systems. Specimens were tested in compression and tension up to 850°C and a detailed study of the micro structure as a function of plastic strain and temperature was carried out by light and electron microscopy. It was shown that the composite strength tested in compression can be accounted for by the simple rule of mixtures if one allows for an additional term representing the effect of Intereprese EXPERIMENTAL PROCEDURE 1) Unidirectional Solidification. Fig. 1 is a schematic drawing of the apparatus used to produce 0.2 in. diam by 12 in. long alloy ingots. The crucible tube is alumina, containing the charge which has been is swaged, or machined to 0.195 in. diam. The lower end of the tube is immersed to 0 .195in in.d iam. The upper end is supported by a 10 mil nichrome wire which lowers the crucible mil nic hr the] wire at a prescribed rate. Surrounding the furnace is a graphite susceptor into which a control thermocouple is inserted. The furnace is insulated with fiberfrax and enclosed in a quartz tube. There is a sliding seal at the bottom around the crucible and one on the top so that an atmosphere may be used for the sample and suscep tor. The power for the furnace is supplied from a 10-kw, 450 kc generator. The skin depth (the skin depth at which the field falls to l/e of its value at the outer surface) for graphite (p = 10 (j-ohm-cm) is 0.1 in. at this fre-

Jan 1, 1970

By H. F. A. Hergt, K. L. Sutherland, J. Rogers

In 1938 Ralston4 reviewed the many attempts to find a satisfactory collector for the separation of cassiterite from its ores and in 1944 Dean and Ambrose2 summarized some further attempts. Generally, soaps and amines are effective but nonselective collectors. We have discovered that reagents containing either the polar group — SO4- or — SO3- are excellent collectors for cassiterite and promise to be selective. The response to these reagents of cassiterite and of minerals commonly associated with it was studied, using the captive-bubble technique. Using these fundamental data, the practicability of separation and concentration of tin was investigated by flotation tests in a 2000-gram Denver cell. Experimental Methods Reagents All inorganic reagents were of Analar grade. The preparation and purification of sodium cetyl sulphate, cetyl trimethyl-ammonium bromide, laurylamine and cetylamine have been previously described.5 The other collectors were commercial surface-active agents, which were used without purification. Tests Captive-bubble Tests and Cylinder Flotation Tests have been previously de- scribed.5,10 The full lines shown in the figures relating solution composition to contact (flotation) distinguish solutions in which contact (flotation) is possible from those in which it is not. The curve is derived by successive approximation and the accuracy is ±0.2 pH units and ± 5 mg. per liter of collector or depressant. Solution compositions for which it was shown experimentally that contact or flotation is possible are marked by a circle, those for which it is not possible, by a cross, and those for which it is doubtful by a cross within a circle. It is assumed that at all other solution compositions within (without) the curve, contact or flotation is possible (not possible). After testing in the collector solution, the mineral was removed, washed, and tested by the captive-bubble method in water, or floated in a cylinder with frother only. In this way the composition of solutions in which a mineral was conditioned but in which properties of the collector solution prevented contact or flotation can be defined. The composition of solutions in which conditioning was possible lie between the full and broken curve, and the experimental results are indicated by a square. The curves show the limits of composition of solutions in which flotation in a cell would be possible but many factors other than those considered in these the determine recovery and grade of a given mineral in practice. Flotation Tests in 500 and 2000-gram Denver SUbmachines,—Melboume tap water, containing 12 parts calcium, 6 parts

Jan 1, 1947

By J. Rogers, H. F. A. Hergt, K. L. Sutherland

In 1938 Ralston4 reviewed the many attempts to find a satisfactory collector for the separation of cassiterite from its ores and in 1944 Dean and Ambrose2 summarized some further attempts. Generally, soaps and amines are effective but nonselective collectors. We have discovered that reagents containing either the polar group — SO4- or — SO3- are excellent collectors for cassiterite and promise to be selective. The response to these reagents of cassiterite and of minerals commonly associated with it was studied, using the captive-bubble technique. Using these fundamental data, the practicability of separation and concentration of tin was investigated by flotation tests in a 2000-gram Denver cell. Experimental Methods Reagents All inorganic reagents were of Analar grade. The preparation and purification of sodium cetyl sulphate, cetyl trimethyl-ammonium bromide, laurylamine and cetylamine have been previously described.5 The other collectors were commercial surface-active agents, which were used without purification. Tests Captive-bubble Tests and Cylinder Flotation Tests have been previously de- scribed.5,10 The full lines shown in the figures relating solution composition to contact (flotation) distinguish solutions in which contact (flotation) is possible from those in which it is not. The curve is derived by successive approximation and the accuracy is ±0.2 pH units and ± 5 mg. per liter of collector or depressant. Solution compositions for which it was shown experimentally that contact or flotation is possible are marked by a circle, those for which it is not possible, by a cross, and those for which it is doubtful by a cross within a circle. It is assumed that at all other solution compositions within (without) the curve, contact or flotation is possible (not possible). After testing in the collector solution, the mineral was removed, washed, and tested by the captive-bubble method in water, or floated in a cylinder with frother only. In this way the composition of solutions in which a mineral was conditioned but in which properties of the collector solution prevented contact or flotation can be defined. The composition of solutions in which conditioning was possible lie between the full and broken curve, and the experimental results are indicated by a square. The curves show the limits of composition of solutions in which flotation in a cell would be possible but many factors other than those considered in these the determine recovery and grade of a given mineral in practice. Flotation Tests in 500 and 2000-gram Denver SUbmachines,—Melboume tap water, containing 12 parts calcium, 6 parts

Jan 1, 1947

By Nathan C. Rockwood

LIME is a very general term applied to products of limestone, in popular treatises often incorrectly, including ground or pulverized limestone used in agriculture. When used without qualifying adjective, the term usually means burned or calcined limestone, or quicklime, or calcia. The corresponding calcined product of magnesite is magnesia. If the calcined rock is relatively pure calcium carbonate, the resulting lime is a "high-calcium" lime; if the rock is dolomite, or a combination of calcium and magnesium carbonates, the lime is a "dolomitic" or a "high- magnesium" lime. There are various grades in between, depending on the percentage of magnesium carbonate and other ingredients in the raw rock. For some industrial purposes only high-calcium limes are suitable; in other processing-as, for example, neutralizing acid wastes -the relative percentages of magnesium and calcium carbonates in the raw material are not important. Limestone is burned (roasted or calcined) in furnaces known as lime kilns by direct exposure to the hot gases and flames. When heated to incandescence, the carbon dioxide content of the rock is expelled, leaving calcium and magnesium oxides, according to the formula usually written: [ ] This thermal reaction is reversible, which requires that the lime be withdrawn from the "calcining zone" of the kiln about as fast as made. Pure calcium carbonate would lose 44 pct of its weight in the calcining process; dolomite, 48 pct. Generally, the lime will retain the approximate size and shape of the piece of rock from which it is made but some few limestones tend to break down into granules or dust. Hence lime (quicklime) comes from the kilns in lumps or granules and normally is packed in water- tight containers in these forms, or is pulverized after calcination.

Jan 1, 1949

By Zay Jeffries

TUNGSTEN has the highest melting point of all the known metals, namely 3350° C.; it is one of the hardest of the metals; it has the highest equiaxing or recrystallization temperature after strain hardening, of any pure metal known. It is particularly distinguished because, when composed of small equiaxed grains, it is extremely. brittle and fragile at room temperature, and when possessing a fibrous structure it maybe ductile and pliable at room temperature. The common ductile metals act in exactly the opposite manner in this respect. The present paper will include a brief note regarding the manufacture of wrought and. ductile tungsten. The metallography of wrought and ductile tungsten in the various stages of manufacture will be considered more or less in detail. The general relationships between the properties of tungsten and other metals will also be considered. A discussion will be given explaining why fibrous tungsten is ductile at room temperature, even though past experience with other metals would indicate that it should be brittle. Finally, a brief note regarding some new fundamental metallographic propositions relating to all metals will be given.

Jan 6, 1918

By D. J. Jr. McAdam

RESULTS of investigation of corrosion-fatigue of metals at the U. S. Naval Engineering Experiment Station have been presented by the author in four papers. 1,2,3,4 In those papers references were given to the work of Haigh in 1917.5 The investigation at Annapolis included a variety of ferrous and non-ferrous alloys. The experiments showed that even slight corrosion simultaneous with fatigue may cause failure at stresses far below the ordinary endurance limit. The experiments also showed that, for most metals, severe stressless corrosion prior to fatigue is much less damaging than even slight corrosion simultaneous with fatigue. The term "corrosion-fatigue" was restricted to mean the simultaneous action of corrosion and fatigue. The combined effect of corrosion followed by fatigue was called "prior-corrosion fatigue." A stress-cycle graph representing corrosion-fatigue is a curve approaching a horizontal asymptote, the ordinate of which may be called a "corrosion-fatigue limit." To avoid confusion in later discussion, the term "endurance limit" will be restricted to mean the fatigue limit obtained by tests in air with specimens as free as possible from stress concentration and from corrosion. The endurance limit as thus obtained presumably represents an inherent property of the metal.

Jan 1, 1929

By W. F. Boericke, T. H. Garnett

The Wisconsin zinc district, or the Upper Mississippi lead and zinc district as it is also termed, lies in the southwestern corner of Wisconsin, and embraces adjacent portions of Illinois and Iowa. It includes Iowa, Grant, and Lafayette counties in Wisconsin, and Jo Davies country in Illinois. In Iowa, Dubuque formerly produced considerable lead, but there has been little mining there in recent years. The map, Fig. 1, shows the entire district, withroads, railways, streams, and the various towns, or "camps," around which the mines are clustered. The hatchwork indicates the areas in which lead and zinc have been mined. The district is about 60 mi. (96 km.) north and south and about 40 mi. (64 km.) east and west. Not all of the territory is mineral bearing, and there are considerable areas that are believed to be barren. The grouping of the mines is patchy and irregular, though certain broad zoncs of mineralization extend almost the full width of the district, as from Mineral Point west through Mifflin and Livingston, and from Shullsburg west through New Diggings and Hazel Green. It is worth noting that the best mines of the district have, to date, been found within 10 mi. ease or west of the fourth principal meridian line, thus lying within a long, narrow, north-and-south belt extending the length of the district. In a field as large as the Wisconsin, which has only within comparatively recent time been worked intensively for zinc, the chances are good for opening new and important orebodies in parts of the district not yet, or insufficiently, prospected. However; the prospecting has been most successful around, or adjacent to, the old lead diggings of nearly a century ago, and the camps that were well known then are still centers of activity. In their order of importance they are: New Diggings, Ben-ton, Mifflin-Livingston, Galena, Linden, Hazel Green, Shullsburg, and Highland. The district is one of the best farming districts in Wisconsin, with deep fertile soil. The farms are large and well improved, and the towns are modern and prosperous. Railroad facilities are good and proximity to Chicago is an asset. Mining is usually done on a leasing system of 10

Jan 1, 1920