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By F. M. Hamilton, H. F. Ameen

Results of a laboratory investigation of some sintering variables are presented. The effect on physical properties of mix component variation and rate of cooling of the sinter is illustrated by crush and tumbler test results and data of reducibility tests and microscopic examination of sinters are shown. The results of using solid additions in the mix to improve bed permeability are given. SOME of the variables encountered in the sintering of iron ores and their effect on sinter properties have been investigated at the Jones and Laughlin Ore Research Laboratory in Michigan. Ores requiring agglomeration before blast furnace utilization may be classed as coarse, intermediate or fine. Coarse iron ore is considered similar to a — 1/4-in. Mesabi wash ore containing some 95 pct of its particles between 94 in. and 100-mesh. Intermediate iron ore is considered similar to our New York State magnetic concentrates in which all the particles are — 20-mesh and about 60 pct are +100-mesh. Fine ores are considered as being at least 100 pct —100-mesh. This paper will deal only with the two coarser classifications. Most of the work has been done in a small experimental batch unit previously described in an AIME1 paper. Results being obtained form a basis for present and future trials in production sinter plants. It is expected that new production units that may be added in the future will benefit from laboratory studies. In general, the results reported here are obtained by laboratory study, but it is Experimental Sinter Machine: The laboratory sinter machine employed in the work consists of a chamber with 1 sq ft of grate area. It is mounted on

Jan 1, 1951

By Helmut Thielsch

During the last three decades a great many arguments have been presented on the subject of "mosaicJ' or "blockJJ structures of metals. Apparently because of insufficient evidence, the "block-structure" theories have never been widely understood among the physical metallurgists in this country, and most investigators among the few that have tried to demonstrate the existence of such an inner strutture Of crystals or grains have failed to recognize also the existence of a lamellar structure. Moreover, little thought has been given to justify the existence of such "lamellar" or "mosaic-block" structures on a theoretical basis. Since properties such as Plasticity; ferro-magnetism, hardness, diffusion, and others may be explained by structural faults in the lattice network of the crystals: the great importance of a more detailed knowledge of the structure within crystals or grains becomes now evident. Because Of the vast extent of the field Of submicroscopic structures, it shall be the purpose Of this paper only to review the more important of the results obtained by other investigators, especially in Germany, where a great deal of attention has been given to mosaic structure during the last three years. The origin of this mosaic patternt and effects of cold reduction and recrystallization will be shown in further studies later on. Imperfections in Crystals The many terms used in the literature to denote structural types of crystals are often not clearly defined. To clear up some of the confusion, the meaning of the more important terms will be given here. ideal, or perfect without any structural imperfections are called "ideal crystals,,or ''Perfect'' crystals,n meaning a Homogeneous interior structure of atoms, ions or molecules, as the case may be. In other words, at every point in the interior of the crystal exactly the same orientation of the crystallographic axes of the coordinate system would exist. The Surface of such a body, if etched with an appropriate etching reagent, would reflect light with perfect uniformity. Crystals of this type are almost nonexistent. Real Crystals.—L'Real crystals"' may contain various types of structural defects, which can be classified into: (I) lineage structure, (2) mosaic-block structure, (3) lamellar structure. The inhomogeneities many,in these groups mean that the orientation of the crystallographic aies will not be the same at every point within the interior of a crystal (or grain of a poly crystalline body). 'Perjecl Real Crystals.—The term "perfect real crystals " is generally used to describe crystals with minute structural or thermo-dynamical inhomogeneities. The former

Jan 1, 1946

By E. V. Potter, H. C. Lukens

INTRODUCTION IN general, during all electrowinning processes, large volumes of gas are liberated at the cathodes of the electrolytic cells. Most of this gas escapes from the electrolyte, but much of it may be absorbed or entrapped in the metal being plated. In many cases, this is not objectionable, but since it is liberated when the metal is heated, it is a potential source of trouble where the metal has to be heated or melted. Since this gas is principally hydrogen, in escaping from a melt it may cause minor explosions and scattering of the molten metal, while in other cases it has been reported to make the metal rise in the molds when cast. Therefore such metals would be more generally useful if all or most of the gas were removed before they were used. In an earlier investigation' the gas content of electrolytic manganese was determined and methods found for removing most of it without detrimentally affecting the properties of the metal. In this paper results of a similar investigation on electrolytic chromium are presented. APPARATUS The apparatus used in these investigations is essentially the same as that used in the manganese work' and is shown in Fig I. It consists of sample chamber A, vacuum or pressure gauge B, volume gauge C, vacuum pump D, hydrogen container E, auxiliary gas chamber F, and furnace G. The pressure in the system is measured by the mercury manometer B. Changes in ' gas volume are measured by volume gauge C which is essentially another mercury manometer in which . the volume of the mercury column is large and can be varied by raising or lowering the well H. In this apparatus the tube had a volume of 100 cc for a 61 cm length. Larger changes in gas volume can be accommodated by auxiliary containers attached to the system at F. The sample is heated by furnace G, the temperature of which is regulated within ± 5°C by an automatic controller. The only change in the apparatus was the sample container which was made smaller because of the chromium metal's containing more gas than the manganese metal and a smaller sample was used. METHOD The measurements were made as follows: The complete system when cold was evacuated and refilled with H2 until all the air was removed. It was then refilled with H2 to the desired pressure, as indicated on manometer B. The temperature was then raised to the desired value and as gas was either liberated from or absorbed by the sample, the height of well H was changed to alter the volume of the system so as to keep the pressure constant. In determining rates of liberation of gas, volume readings were taken at convenient time intervals depending on the rapidity with which the gas was liberated. In determining total volumes, the specimen was held at constant temperature and pressure until

Jan 1, 1948

By E. G. Leonardon, C. Schlumberger, M. Schlumberger

In the search for practical geological problems amenable to solution by the potential methods, the geophysicist is led to study mathematically various theoretical cases. In these idealistic discussions, the media under consideration are generally supposed to be homogeneous and iso-tropic. The geophysicist, of course, realizes perfectly that these conditions do not occur in their entirety in reality. However, the assumptions made are justified, because very often they are necessary in order to render possible an exhaustive study of a given problem, which otherwise would be too complicated, and would not lend itself to a complete mathematical analysis. Of the above two assumptions, that concerning the homogeneity of a given geological formation is satisfactorily realized except in so far as isotropy is concerned, since this property is not often encountered in practice. As a consequence, it is very desirable for the geophysicist to have quite an extensive knowledge of the properties of anisotropic formations, and of the laws that govern the propagation of electric current therein. With such principles in mind, he will be able to decide whether the conclusions arrived at in simple, isotropic conditions are still correct in more complex cases, or in what way they must be modified or adapted in order to constitute a sound basis for the interpretation of the results obtained in anisotropic media. On the other hand, the fact that in anisotropic formations the mobility of the ions is greater along the strike than perpendicular thereto can be utilized for determining the direction of the dip by induction measurements. We therefore propose to study in three successive chapters the following points: 1. Propagation of the electric current in anisotropic media. 2. Some consequences of the anisotropy of geological formations with reference to the surface electrical measurements, and their interpretation. 3. Determination of the direction of the dip of anisotropic formations by surface induction measurements.

Jan 1, 1934

By A. Adiaddevich

Petroleum has been found in Russia in various localities from north to south, as may be seen from the list given below: (a) In the basin of the Petchora river, Northern Russia. (b) In the basin of the Volga river, in the governments of Samara and Saratoff. (c) In the government of Astrakhan and in the Uralsk territory, close to the northern and eastern coast of the Caspian sea. (d) At Grozny in Northeastern Caucasus. (e) In the Daghestan territory, Eastern Caucasus, on the Caspian sea. (f) On the Apsheron peninsula (Baku and other districts) close to the Caspian sea shore. (g) On the island of Tcheleken in the caspiah sea, also on the island of Sviatoi. (h) In the Transcaspian territory on the Neftianaia Gora (Oil hill) and on the surrounding hills. (i) In the Ferghana valley in Russian Central Asia. (j) On the Kertch-and Taman peninsulas on the Black sea. (k) In Siberia it has been discovered in the Transbaikal territory and on the island of Sakhalin.. ' ' In the above-mentioned districts petroleum has been found to exist under different geological conditions and to vary in its chemical and physical properties. At the present time petroleum is produced in Russia at Baku, Grozny, on the island of Tcheleken, in the Ferghana district, and in the Uralsk territory. The yearly production in 1912 throughout the Russian Empire amounted to 69,400,000 barrels, of which the Baku fields were responsible for 52,000,000 barrels. This shows that the Balm fields on the Apsheron peninsula are the chief oil-producing centers in Russia, being at the same time the oldest of all our oil fields. In this paper I shall discuss the Baku fields only, leaving all the others until a later date. The Apsheron peninsula in the Eastern Caucasus protrudes into the Caspian sea in the shape of a triangle some 47 miles long covering a total area of some 750 square miles. The eastern part of the peninsula is a flat, slightly rolling plain, rising in its highest parts to 140 to 170 ft. above

Jan 1, 1915

Occasionally it is interesting, and sometimes useful, to review the past for early references to our industry, and to learn of the trials and travail passed through before it arrived where it now is- and the results of such a review follow. Some time ago one of our modern playwrights and poets, Arthur Guiterman, turned to coal, with the following result: Afar in the Carboniferous time I grew in Paleozoical slime, A lepidodendron with boughs on my stem And lepidostrobuses grew out of them. My roots in the mud of the ages I spread And up to the heavens I vaunted my head, I throve in the heat of tropical sun, And now I am coal at two dollars a ton

Jan 1, 1939

By I. L. Greninger

THE property of the Andes Copper Mining Co. is in the central part of the Republic of Chile, Province of Atacama, 147 km. (91.5 miles) eastward by rail from the port of Chanaral. At this point the Andean system is made up of two principal ranges. The mine is on the westerly slope of the outer, or western, range, at a mean elevation of 3250 m. (10,500 ft.). A meter-gage railroad extends from the company's port at Barquito, near Chañaral, to the reduction plant at Potrerillos. This road has a total length of 151 km. (94.0 miles), of which 93 km. (57.79 miles) are owned by the Andes Copper Mining Co. The remainder of the road is owned by the state. The company operates its trains over the portion of the road owned by the state, under an agreement with the Chilean Government. The mine is connected with the reduction plant by a meter-gage railroad, 10 km. (6.214 miles) long, which extends from the coarse-ore bins at the metallurgical plant to the underground storage bins at the mine. Tunnels make up 60 per cent. of the total length of this railroad. As is characteristic of the Andean region in Chile, the topography of the locality is extremely rough, and a number of points near the mine have elevations of from 15,000 to 16,000 feet. History of Potrerillos Mine The ore occurrence has been known for many years, and many of the claims under individual ownership were worked in a small way before the property was acquired by the present owner—the Andes Copper Mining Company. The highest grade oxide ores near the surface were mined by primitive methods and, after sorting, the product, assaying around 15 per cent, copper, was hauled by mule carts a distance of about 80 km. (49.71 miles)

Jan 1, 1929

By G. R. Brophy, A. J. Miller

The Grossmann principle1 for the calculation of hardenability of steel from composition is attractive because of its simplicity. It postulates that the hardenability of a steel for any particular grain size may be expressed in terms of an ideal critical diameter, which is the product of an ideal critical diameter for a "pure" iron-carbon base multiplied by a succession of factors for each element of composition contained, including the incidentals. It infers that the multiplying factor for a given quantity of an element is constant for all combinations of composition. Gross-mann has stated that in the great majority of cases the experimental values of hardenability are found to be well within 10 per cent of the calculated values. The validity of the scheme has been confirmed in principle by Crafts and Lamont2,3 and by Kramer et al.4 Their results differ from the original in the magnitude of the effect of some elements but, since they accepted the product concept and followed its direction, it is to be ex~ected that similar results would be obtained. Crafts and Lamont, in their second Paper, recognized that the factor relations for manganese and nickel were not continuously linear, but beyond certain critical amounts increase sharply. Austin, Van Note and Prater6 demonstrated nonlinear relations between hardenability and alloy contents. Their curves for chromium, silicon, manganese and nickel were all convex upward to show decreasing incremental effects. They concluded that Grossmann's factors under-evaluate the hardening effect of low percentage additions of these elements, and overevaluate the larger additions. More recently W. Stevens has found that the factor method fails when applied to complex steels containing two or three principal alloying elements other than carbon. Multiplying factors derived from his results bear a complex relation to composition and are not constant for a given amount of an element as the base composition varies. C. A. Liedholm7 found that, using either the Grossmann or the Crafts-Lamont multiplying factor values, not only were the relative hardenabilities of two heats of S.A.E. 6130 chromium-vanadium steel

Jan 1, 1947

ALTHOUGH the open-hearth charge contributes CO, C02, H2, A and water vapor to the combustion gases and absorbs oxygen from them, in the main the thermal effects in the melting charge and molten bath can be considered independently of those in fuel combustion; the latter then is regarded simply as the source of the net heat required to finish a heat of steel. First of all, it should be remembered that a large percentage of the heat supplied to the bath is furnished by oxidation of the various elements in the charge itself. If this charge consisted of 80 to 100 per cent of hot metal and the oxidation were accomplished by blowing in air or oxygen, as in the bessemer converter, the net heat absorption would be negative; that is, the bath would contribute part of the heat required to keep the melting chamber hot, in addition to that contained in the finished steel and slag. In actual open-hearth practices, probably the nearest approach to this is in the duplex furnace, charged with bessemer-blown metal and some hot metal, where very little heat is required to complete the refining and nearly all the heat energy from fuel combustion is used to keep the roof and walls of the melting chamber up to around 2900 to 3000 F (1600 to 1650 C), so that the bath will not cool off during the refining. The other extreme is with all-cold charges containing around 80 per cent steel scrap and 20 per cent cast iron or cold pig iron, in which case a very large proportion of the heat in the bath at tap is supplied from the fuel combustion. THERMAL EFFECTS IN MELTING In a typical heat, the fuel furnishes about four million British thermal units per ton of steel produced. The heat required, for the metallurgical processes is not easily defined in useful manner but it ranges downward from about one million Btu, depending not only on the charge but on the manner of calculation. In, any event, this requirement appears. small in comparison with the

Jan 1, 1964

By E. H. Crabtree, T. C. King

The ferrosilicon grinding unit at the Central Mill of the Eagle-Picher Mining & Smelting Co. near Picher, Okla., was completed in March 1947. The object of the plant was to grind pigs of ferrosilicon, having a size of approximately 1½ by 4 by 12 in. and an analysis of 85. pct Fe and 15 pct Si, to approximately 100 mesh by crushing and wet grinding in a ball-mill classifier circuit. The minus-100 mesh ferrosilicon had formerly been purchased, and was used as medium in the heavy media process for treatment of lead-zinc ores. From the standpoint of dollars and cents, the cost of minus-100 mesh ferrosilicon was roughly $40.00 per ton more than pigs of the corresponding alloy delivered to the mill. Estimated wet grinding costs were considerably below this figure. The possible saving in cost of make-up medium for the cone plant was particularly attractive since, at that time, the plant losses averaged over four tons of minus-100 mesh ferrosilicon per day. Aside from the probable saving on the grinding charge, the need for such a unit was twofold. First, periodic fluctuations in the differential between the top and bottom densities of the cone were thought to be detrimental to metallurgy. There was little doubt that an intermediate differential existed at which the heavy media separa- tion was most efficient, representing a compromise between concentrate grade and tailing loss. Furthermore, if a finer, but considerably cleaner, medium could be obtained, there was the possibility that the differential could be decreased without increasing the viscosity, or conversely, the viscosity of the medium decreased without increasing the differential. Preliminary to experimental work aimed at pegging the cone differential and circulating medium viscosity at whatever values were found to be most efficient, it was essential to have control over both the nonmagnetic content of the medium and the particle size of the contained ferrosilicon. The latter was possible by means of a grinding unit at the mill. Second, whereas the ferrosilicon alloys are made by a number of manufacturers, only two, to our knowledge, grind it in any quantity for use in heavy media plants. For all practical purposes, the Central Mill was limited to one source of supply, a particularly vulnerable position. In case the supply was cut off, it was thought that pigs of the 85 pct Fe, 15 pct Si alloy could be obtained elsewhere, providing means of grinding them was available. There was no published information available covering wet grinding of ferrosilicon. Dry grinding in batch mills and in continuous mills with air classification was being practiced, but the cost of grinding was excessive and the dust condition objectionable. It appeared that primary and secondary crushing was no particular problem, providing heavy duty equipment was used;

Jan 1, 1949

By Eugene P. Pfleider

Research indicates that the cube diamond is a superior stone for drill bits. It can be oriented to combine a long cutting edge with structural strength and high resistance to wear. Test bits set with preferred orientation give double the bit life at astoundingly low diamond loss in comparison to oriented octahedral diamonds. A PROGRAM of research on the orientation of diamonds in drill bits has been under way for several years at both the United States Bureau of Mines Experimental Mine at Mount Weather, Va., and the School of Mines and Metallurgy of the University of Minnesota. Reports on past work done both in the laboratory and the field are available in the technical press.1,3,4 The results of such drilling, done under comparable conditions, show that bits having diamonds oriented in a direction that combines structural strength and greatest hardness not only can advance somewhat faster than random set bits but can do this with a unit diamond loss of 50 pct or less. Several bit manufacturers have initiated the training of diamond setters in the principles of orientation on the basis of the above-mentioned research results. The basic information on the crystallography and hardness variation of the diamond was presented in an earlier paper,' which pointed out that the diamond is several hundred times harder along certain directions and certain faces than on others. The same article discussed the drilling results obtained with a group of nine bits having octahedron diamonds set with on-point, positive (gouge) rake, and negative (drag) rake orientations. The testing of oriented cube diamonds is an extension of this research program, employing the same procedures and equipment (Hy Mac hydraulic drill unit, EXT diamond core bits, St. Cloud Pink granite) as previously described. This current work covers the test experience of seven bits set with cube diamonds running approximately 10 stones per carat. The individual stones were near perfect cubic form; hence it was simple to orient them in any desired direction. The cube is a comparatively rare crystal form of the diamond, although considerable numbers are produced from the Congo. It is understood that most of the cube diamonds are retained in Africa, where they are either used locally for diamond bit manufacture or ground up to make powder. They have been considered to be an inferior stone for drilling purposes.

Jan 1, 1954

By H. A. Buehler

The Ozark region occupies a large part of the southern half of Missouri, the northern portion of Arkansas and comparatively smalll areas in northeast Oklahoma, southwest Kansas, and southern Illinois. It is a roughly elliptical plateau which has been deeply dissected by stream erosion, and which slopes imperceptibly into the prairie regions to the north, east, and west, but which terminates rather abruptly along the Arkansas River on the south and Tertiary lowland to the southeast. The Boston Mountains extending for a distance of some 200 miles (321 km.) along the Arkansas River rise to an elevation of 2000 ft. (609 m.), forming the most prominent topographic feature of the region. The so-called St. Frangois Mountains in St. Frangois, Madison, and adjoining counties in southeast Missouri, form a prominent but more restricted topographic feature, the highest point rising to an elevation of 1800 ft. (548 m.). The remainder of the region is largely a plateau area varying from 800 to 1500 ft. (243 to 457 m.) in elevation. Stratigraphy The region is underlain chiefly by sedimentary formations, which outcrop in roughly concentric bands around a comparatively restricted area of igneous rocks in the St. Frangois Mountain district. Although located geographically near the eastern edge of the Osarks, the St. Frangois Mountains have apparently suffered the greatest orogenic movement and the lowest formations of the succession are exposed in their immediate vicinity. The various sedimentary formations of the region do not show any considerable metamorphism and have suffered little change since consolidation. With the exception of a few basic intrusions in Ste. Gene-vievg County and a pegmatite dike in Camden County, Missouri, there is no evidence of igneous action, since the first sedimentary beds were deposited.

Jan 1, 1918

By Leo B. Bicher, Donald L. Katz

A correlation is presented for predicting the viscosities of light paraffin hydrocarbon mixtures such as natural gases for temperatures from o° to 4o0°F. and for pressures fro1 atmospheric to I0,000 lb. per sq. in. The correlation is based on the viscosity data for the methane-propane system and requires only a knowledge of the molecular weight of the naturaI gas. The viscosities of natural gases reported in the literature up to 2500 lb. were reproduced by the correlation with an average deviation of 5.8 per cent. Introduction The viscosity of a natural gas is required whenever calculations are made of the pressure drop that occurs while the gas flows through pipes or porous media. Methods of predicting the viscosities of gases at the present operating pressures are not available. This paper presents a simple method of predicting the viscosity of a natural gas in the single-phase region from its molecular weight, temperature, and pressure. Viscosity oF Methane-propane Mixtures The viscosity of methane, propane, and four of their binary mixtures, 20,40, 60, and 80 mol per cent, have been determined for pressures from 400 to 5000 lb. per sq. in. and temperatures from 77" to 437 F., with an experimental accuracy of 3.2 per cent.2 The apparatus used in the investigation was a modification of that employed in previous studiesaJ4 on the viscosity of normal paraffin hydrocarbons. It consists of a viscosimeter of the rolling-ball, inclined-tube type,5>k7 with auxiliary equipment for making up and charging binary mixtures into the viscosimeter.~ The viscosity data on the methane-propane mixtures have been plotted as a function of molecular weight with lines of constant pressure, charts of constant temperature in Figs. I to 3. These charts are extrapolated at temperatures below 77°F. and at pressures above 5000 lb. per sq. inch. Prediction OF Viscosity from Molecular Weight of a NaturaI. Gas At atmospheric pressure the viscosity of light hydrocarbon gases increased with increased temperature, contrary to the change of viscosity of liquids with temperature. The atmospheric viscosities of the normal paraffin hydrocarbons have been determincd by several investiga-tors 3,4,9,10,12,15,16,17,19 and are plotted in Fig. 4 as a function of molecular weight, with extrapolation to 896'F. and to 220 molecular weight. Data for isopentane and normal pentane show less than 2 per cent difference in viscosity, indicating that Fig. 4 can be used for isomeric parafin hydrocarbons with an accuracy of approximately 2 per cent. Trautz and Sorg'7 determined the atmospheric viscosities 01 methane-propane mixtures and showed that they are proportional to the molecular weight. The viscosities of these mixtures

Jan 1, 1944

By P. E. Doherty, R. S. Davis

Sub boundaries and micropores, as well as certain other imperfections, may be revealed in aluminum by the formation of pits on the surface during cooling from elevated temperatures. The pits are attributed to the condensation of vacancies from supersaturated solution. This "vacancy pit" phenomenon has been used as an etching technique for studying the structure of aluminum specimens grown from the melt. Three fundamental structures were studied: stria-tions, cells, and dendrites. Two types of striations, as well as a crosswise structure are reported. Mic-roporosity is observed to occur in the cell walls on freezing. Subboundaries between primary, secondary, and tertiary branches are observed in dendritic growth. A special case is cited in which cellular growth suppresses the formation of striations. SMALL, well-defined pits have been observed to form on the surfaces of electropolished aluminum specimens during cooling from elevated temperatures.' This phenomenon was attributed to the condensation, from supersaturated solution, of vacancies at particular points on the surface. It was shown that the amount of cooling required for the formation of pits increased exponentially with decreasing holding temperatures in a way that was consistent with the thesis that a critical supersaturation of vacancies was required for the pits to form. Pits do not form in the vicinity of certain imperfections, namely, subgrain or normal graind boundaries, phase boundaries, certain surface irregularities, and pores. The width of the pit-free region increases with decreasing cooling rate. This observation suggests that the imperfections in question are effective sinks for vacancies and that the pit-free region around them is material that is not sufficiently supersaturated with respect to vacancies to nucleate the surface pits during cooling.

Jan 1, 1962

By James Pollock

SUMMARY THE possibility of colloidal deposition of cinnabar has been neglected. In opalite deposits cinnabar exists in particles within or near the colloidal size range. Colloidal processes have been admitted to be operative in hot springs and low-temperature deposits similar to most cinnabar deposits. Mercuric sulphide sols are stable to elevated temperature and pressure, and in nature probably are chiefly affected by the electrolytes in solution, dilution of colloid, and presence of protective colloids as silica. The stability of mercuric sulphide sols to electrolyte is measured, and shown to be greatly increased by dilution and by the protective action of silica. Mercuric sulphide sols follow the Schulze-Hardy valency rule, therefore the precipitating power of complex mixtures of electrolytes can be computed roughly. The stability of mercuric sulphide sols is shown to be greater than the equivalent precipitating power of the electrolytes in a hot spring depositing mercuric sulphide. It is concluded that finely divided or earthy types of cinnabar are colloidally deposited. POSSIBILITY OF COLLODIAL DEPOSITION While colloidal solution has been suggested as a means of transport for a number of minerals, such as the sulphides of antimony, arsenic, and iron, it has been neglected in connection with mercury. This is surprising because there exists positive evidence that cinnabar is present in certain deposits in particles of colloidal or near colloidal size. Colloidal transport could result from either the rapid dilution or neutralization of alkaline sulphide solution bearing mercury coming in contact with deep ground waters, or from colloidal solution near the original source and subsequent flow to the point of deposition unchanged. That the dilution of a mercuric alkaline sulphide solution will precipitate mercury sulphide in colloidal form has been demonstrated a number of times and is easily confirmed. The dilution hydrolyzes the alkaline sulphide Na2S to the corresponding hydroxide and hydrosulphide NaOH and NaHS, and the diminution of the concentration of alkaline sulphide reduces the solubility. It is not the contention of this writer that colloidal deposition is the mode of transport of mercuric sulphide in all mercury deposits, but that the stability of a mercuric sulphide sol, as demonstrated below, in waters that are similar to those that have deposited mercuric sulphide necessitates consideration of this possibility in many deposits, especially those of the hot-spring and so-called opalite type. EVIDENCE OF COLLOIDAL DEPOSITION Ross1 has shown that most deposits of quicksilver are formed at low temperatures and pressures, and probably by solutions that have relatively simple chemical compositions. In most cases the solutions are probably similar to those observed in hot springs, and in two instances-at Steamboat Springs, Nevada, and Sulphur Bank, California-hot springs have been reported by Becker as actually depositing cinnabar.2 Opalite deposits were believed by early investigators to be surface phenomena

Jan 1, 1944

Contents A-Metal Mining B-Minerals Beneficiation F-Coal

Jan 11, 1951

By Rudolph Gahl

RUDOLF GAIL, Miami, Ariz.-Since I wrote the paper on flotation which is in your hands, important developments have taken place, and, for this reason, I will try in a few words to bring it nearer up to date as far as the Inspiration plant is concerned. You, may have noticed that in the Inspiration concentrator, flotation is not solely relied upon for the recovery of the coarser material, but that flotation tailings are split into a sand and a slime product on drag classifiers. The sand product is treated on tables which thus supplement the work of the flotation machines. Extensive tests have shown, us that, if we wanted to, we could leave out these tables and substitute additional flotation machines, as they will make fully as good, if not a better recovery than tables on the deslimed feed, but the treatment would be more expensive, especially in view of the fact that oils are required which cost more than those which we are now using in our main flotation plant. We have, however, decided to apply flotation treatment to our table middlings. I would also like to add a few words regarding the treatment of oxidized copper ores. Although our experience shows that the addition of hydrogen sulphide and other soluble sulphides effects a very good recovery of copper carbonates with certain ores, we have not been able to prove that we could use it advantageously for the ore mixture which we are treating in our concentrator, and for this reason, have looked toward leaching for extracting the carbonate and silicate copper that we are losing now. Experiments in this direction are going on and are giving very encouraging results. It may interest you to hear that we intend to use limestone for the precipitation of the copper which goes into solution, as electrolytic precipitation seems to be out of the question on account of the diluteness of the resulting solutions, and precipitation by iron was rightly objected to on account of the unavoidable contamination of the water supply. We feel very hopeful about the success of our limestone precipitation which, if it holds what it seems to promise, will develop into a novel feature of copper metallurgy.

Jan 10, 1916

By J. B. Austin, R. H. H. Pierce

IN developing a consistent picture of the thermal expansion of the commercial chromium steels, which cover a range of, carbon contents, it is desirable to know the expansion in the limiting case of the binary, carbon-free, iron-chromium alloys. We have, therefore, determined the thermal expansion of a series of five special alloys, ranging in chromium content from 3 to 10.5 per cent, with not more than 0.03 per cent carbon, over a temperature range extending beyond the transformation region; this low carbon content enables us to draw reasonably reliable conclusions as to the behavior of the carbon-free system. Moreover, the measurements serve to determine the beginning and the end of the alpha-gamma transformation; and they emphasize once more the fact that a transformation temperature determined by any method in which the specimen is .cooled at an appreciable rate is apt to be seriously in error, particularly if the metal contains a transformation-retarding element such as chromium or managanese. The lag, or undercooling, observed at the ?-a transformation is explained in terms of the influence of temperature on transformation velocity; the rather unusual shape of the ? loop is attributed to a change with temperature and with composition of the distribution of chromium between the alpha-iron and gamma-iron solid solutions. The exact composition of the alloys which were obtained through the courtesy of Dr. W. Rohn, of the Heraeus Vakuumschmelze A-G., is given in Table 1. Determinations of the linear thermal expansion and of transformation temperature were carried out in the vacuum dilatometer previously described,1 using a rate of heating and of cooling of 3.0° to 3.5° per minute unless otherwise stated. Magnetic susceptibility, which was measured in studying the rate of transformation, was determined with a magnetic balance, which also has. been described.2

Jan 1, 1935

By F. G. Tryon, F. E. Berquist

Our task is to make a prospecting trip over the whole field of mineral economics which other lectures of this series will explore in detail. The old timers who really understand mining warn us that its economic aspects are often neglected, and this we find to be true. We shall try to show that mineral economics deserves recognition as a separate branch of economic science with urgent and distinctive problems of its own; that to cultivate it requires a fusing of the viewpoint of economics with that of geology and engineering; and that the help of both economists and technical men is needed in exploring its problems and in training workers in the field. To save time, we shall pass over the familiar subjects of production, consumption, and distribution which bulk as large in the market analysis of the minerals as they do in other commodities. The existence of these problems may be taken for granted and attention centered rather upon those that differentiate mining from other branches of industry. What then is the case for an economics of minerals? Why set up a new compartment in a branch of knowledge that is already well subdivided? Do not the established principles of economic theory apply here as elsewhere? In pleading for recognition of mineral economics one often finds that

Jan 1, 1932

By A. T. Shurick

TILE present economic crisis in bituminous coal is substantially the most insidious, and critical, in the modern history of the industry. The large consumption deficit that has gradually developed (almost unawares), has culminated in a situation that has forced home the urgent necessity for prompt and radical remedial measures, such as the various mergers now in course of negotiation. Conditions today are sufficiently comparable with those in the iron and steel industry, preceding the formation of the United States Steel Corpn., to suggest the possibility of a sweeping super-consolidation, that all but staggers the imagination. The important function of the banker in this, and lesser projects, is too well known to require comment, and it is important that we understand clearly just what these functions are. Certain features in banking practice came up for consideration in connection with a rather exhaustive economic study into the prospective future of the coal industry, upon which I was recently engaged for an Eastern bituminous interest. This survey was made for the purpose of effecting a decision on certain pressing questions of policy, involving considerable capital expenditures, that would be compatible with the flattening out in the curve of production in recent years. An examination of the TRANSACTIONS, and the coal literature generally, failed to disclose any pertinent, and authoritative data, on this subject. This was more or less characteristic of the whole survey, which had involved a large amount of original research, and measures were taken to procure the required information. The following notes have been compiled largely from the data thus collected, supplemented with material, suggestions and criticisms, by several of the larger banking houses active in coal, together with personal memoranda of my own.

Jan 1, 1928