Search Documents

By Alfred E. Hunt

The charge to be described was made in a seven-ton furnace, with a hearth twelve feet long and eight feet wide, with three gas and three air ports on each side. The stock of the entire heat was charged cold in one hour and five minutes, a part of the pig being first placed upon the bottom to protect it, then upon it the plate-scrap and blooms, and finally the remainder of the pig—some two thousand pounds. In fire hours and twenty-five minutes after beginning the charge the metal was melted down level, and two hundred pounds of hot twelve-per cent. spiegel was charged, care being taken to have it entirely immersed in the bath. In two hours more the bath was thoroughly melted and hot, and began to boil, i. e., the carbon began to be oxidized and evolved through the bath of covering slag as carbonic acid and carbonic oxide gases. Seventy-five pounds of lumps of Republic specular iron ore were added at this time, increasing the action, so that in ten minutes after the metal was in active ebullition. A test of the metal showed it to have about 0.90 per cent. carbon. One hour after the first ore was added a test was again taken, after thorough rabbling of the metal, and it was found to be 0.37 per cent. carbon. One hundred pounds more of lump Republic ore and about seventy-five pounds of limestone were then added, and fifty minutes later, after the bath was thoroughly rabbled, a -test showed the metal to have 0.23 per cent. carbon. Twenty-five pounds more of Republic iron ore were added and the metal allowed to boil for twenty minutes, when a test, after rabbling, showed the carbon to be 0.18 per cent. and the manganese to be 0.01 per cent.; the slag fracture was vitreous and of a very dark-green color. About forty pounds of limestone were added, and, the metal being hot and in a state of quiet ebullition, a hickory pole of twelve feet length and about four inches diameter, was run through the aperture in the centre door and held in a steady inclined position in the bath, with the end touching the bottom, the pole being shoved in further as it was burned away. The bath was carefully watched to see that the action that ensued was not too violent, the pole being several times

Jan 1, 1884

The following is an incomplete list of members and guests who called at Institute headquarters during the period July 11, 1918 to August 11, 1918. John Carter Anderson, Tucson, Ariz. Edson S. Pettis, San Francisco, Cal. Lieut. Frank A. Ayer, Tyrone, N. M. Wm. H. Rettie, Yonkers, N. Y. W. R. Canton, McGill, Nev. J. T. Robertson, Port Richmond, S. I. Alden Crankshaw, Palmerton, Pa. Harry O. Robinson, Margarita, John Davenport, W. Norfolk, Va. Venezuela. A. Faison Dickson. C. K. Seng, Gilbert, Minn. F. A. Fahrenwald, Cleveland, C). E. S. Sheffield. L. Hall Goodwin, New York. H. G. Smith. W. H. W. Hamilton, Baker, Ore. Harry M. Spoor. Floyd D. James, St. Louis, Mo. H. H. Stoek, Urbana, Ill. George A. Laird. Arthur L. Tuttle, Copperhill, Tenn. J. W. McBride, Spokane, Wash. Thor Warner, Phoenix, Ariz. Arthur Notman, Bisbee, Ariz. Christopher G. Atwater, Manager Agricultural Dept., The Barrett Co., is in Washington serving the U. S. Navy Bureau of ordnance in connection with the Navy nitrate plant recently authorized by Congress. Edward Ludlam Blossom announces his marriage to Mabel Townsend, daughter of Mr. and Mrs. George Comings Mills, on Wednesday, July 17, 1918, at New York City.

Jan 9, 1918

By O. C. Wheeler

Production in Colombia attained a new high during 1940 when it reached a total of 25,607,976 bbl. Of this amount, the Tropical Oil Co. produced 21;426,492 bbl., including 268,586 bbl. of petroleum condensate, and the Cololmbian Petroleum Co. produced 4,181,484 bbl. from its Barco property. The wildcatting program of different companies in the Magdalena Valley that was initiated during the previous year was continued but with results that were decidedly disappointing. Ten wells were drilled in the Magdalena Valley between the approximate latitudes of Puerto Wilches and Puerto Berrio and nine of these were dry; the tenth was a small producer of no commercial importance. The prospects of finding new fields in the Magdalena Valley thus received a serious setback, since some of the tests drilled were on well developed surface structures. The prospects of the Valley, however, have by no means been exhausted and drilling operations are being continued on other prospects. One additional wildcat was drilled outside the Magdalena Valley on the Colombian Petroleum Company's Barco Concession, which brought to 11 the total number of wildcats drilled in Colom-bia during the year. This well, known as

Jan 1, 1941

By O. C. Wheeler

Production in Colombia attained a new high during 1940 when it reached a total of 25,607,976 bbl. Of this amount, the Tropical Oil Co. produced 21;426,492 bbl., including 268,586 bbl. of petroleum condensate, and the Cololmbian Petroleum Co. produced 4,181,484 bbl. from its Barco property. The wildcatting program of different companies in the Magdalena Valley that was initiated during the previous year was continued but with results that were decidedly disappointing. Ten wells were drilled in the Magdalena Valley between the approximate latitudes of Puerto Wilches and Puerto Berrio and nine of these were dry; the tenth was a small producer of no commercial importance. The prospects of finding new fields in the Magdalena Valley thus received a serious setback, since some of the tests drilled were on well developed surface structures. The prospects of the Valley, however, have by no means been exhausted and drilling operations are being continued on other prospects. One additional wildcat was drilled outside the Magdalena Valley on the Colombian Petroleum Company's Barco Concession, which brought to 11 the total number of wildcats drilled in Colom-bia during the year. This well, known as

Jan 1, 1941

By Eckley B. Coxe

THE plummet lamp, to which I called the attention of the Institute, at the Bethlehem meeting, in August, 1871, with the improvement of the compensating ring, suggested by Mr. Heller, having come into general use for mine surveying in this country, and my attention having been called to the fact that it could not be employed in mines in which there was danger of meeting with fire-damp, I have so modified it that it can be used in all cases with safety. Mining engineers, who are in active practice in those districts where fire-damp is met with in the mines (and I am sorry to say it is becoming much more common in the anthracite regions), know how dangerous their work is when they are called upon to survey such mines, particularly when they are obliged to run lines in those parts of a mine which have been unworked, since by opening of doors, brattice, etc., to get the sights, they are liable to disarrange the currents of air, and cause any fire-damp that may have accumulated in the old workings to find its way into the levels, etc., where the party is at work. It is, therefore, very dangerous to leave an open light (such as the original form of plummet lamp) in an old breast or gangway, even when the safety lamp has shown that no fire-damp is present, for the opening of the doors, etc., may drive the fire-damp to the light, and thus endanger the lives of the engineers. The improved form of plummet lamp, now shown to you, can be used either with or without the safety apparatus. Upon the top of the plumb-bob portion of the old lamp a screw is cut, upon which a ring A is screwed. (See Plate II.) On the external cylindrical part of this ring two small conical holes are drilled, 180° apart. The compensating ring, by which the plumb-bob part of the lamp is suspended, passes over the ring A, and is fastened to it by two small screws having conical points, which fit into the conical holes in the ring A. The safety apparatus resembles, to a certain extent, that of the Mueseler lamp. It consists of a ring B and plate C, which are united by four rods. The plate C has a cylindrical hole in the middle, and four apertures distributed radially around it. In the central cylindrical hole is fitted a conical brass chimney, which projects below the plate C, and is fastened to the latter, being kept ver-

Jan 1, 1875

By J. P. Hammond, C. J. McHargue, S. E. Adair

Cold-rolled sheet textures have been determined for binary solid solutions of aluminum, columbium, tantalum, and zirconium in titanium. An alloy containing 3.8 pct Al had a (0002) [10101 texture, whereas alloys with the other elements had rotated (0002) [10101 textures similar to that of iodide titanium. THERE have been relatively few studies of the effect of alloying on deformation textures. A second element may be present in the base metal in solid solution and/or as a second phase. The literature offers no satisfactory explanation for the effects of solid solution alloying on textures noted thus far. For example, there is no satisfactory explanation of the difference in the textures of copper and a brass. The most complete study of the effects of solid solution alloying on deformation textures has been that of Brick, Martin, and Angier.¹ These investigators reported that the copper texture was retained by alloys of copper with up to 30 pct Ni, less than 5 pct Zn, less than 2 pct A1 or Co up to the limit of solubility. Copper containing more than 5 pct Zn, more than 2 pct Al, or the maximum soluble concentration of tin, silicon, or manganese showed the deformation texture of a brass. Bakarian² reported that additions of 0.20 pct Ca to 99.98 pct Mg or 2.0 pct Mn plus 0.15 pct Ca to magnesium resulted in entirely different textures than for the pure magnesium. The texture obtained for high-purity magnesium sheet showed the basal plane to be concentrated parallel to the rolling plane. The texture obtained for the alloy containing 0.20 pct Ca had the basal planes concentrated in elliptical areas whose centers were tilted 15" from the center of the pole figure toward the rolling direction. This split basal orientation was even more pronounced in the alloy containing 2.0 pct Mn and 0.15 pct Ca. Fuller and Edmunds" studied the rolled sheet textures in a zinc alloy containing 1 pct Cu and 0.01 pct Mn. The basal pole figure of this alloy contained a region of strong concentration not found in the pole figure for pure zinc.' In the above cases, results were discussed in terms of possible changes in slip and/or twinning systems and critical shear stresses. However, there were no experimental data to relate these speculations with the observed textures. It has been suggested that the deformation textures of titanium, zirconium, and beryllium could be directly ascribed to their low c/a ratios. The complex deformation mechanisms of titanium" also have been suggested to be characteristic of hexagonal close-packed metals with low c/a ratios. The purpose of this investigation was to study the cold-rolled sheet textures in binary titanium-base a alloys in which the c/a ratios were greater than, less than, and about the same as the c/a for iodide titanium. The annealed textures of these alloys will be reported in a subsequent article. Materials and Methods The chemical analyses of the metals used in this investigation are given in Table I. The alloys were prepared as 15 g buttons on a water-cooled copper block in a vacuum arc-furnace. The furnace was evacuated to pressures of the order of 10.' mm Hg, flushed with 99.98 pct pure argon, and melting was carried out in 0.2 atm pressure argon. Each button was remelted until radiographs and chemical analyses indicated complete solution of the solute elements. All buttons were forged and homogenized 72 hr at 500°C. The buttons to be rolled were ground and etched to sizes and shapes suitable for the rolling

Jan 1, 1954

The United States Coast and Geodetic Survey has announced the completion of a new outline map of the United States on the Lambert conformal conic projection, scale 1-5,000,000. This map is intended merely as a base to which may he added any kind of special information desired. The shore line is compiled from the most recent Coast and Geodetic Survey charts, state names and boundaries, principal rivers, capitals, and the largest cities in the different states are also embodied. The value of the new outline map on the Lambert projection can best be realized when it is stated that it shows that throughout the largest and most important part of the United States, that is, between latitudes 30 ½ and 49°, the maximum scale error is only 0.5 per cent. This amount of scale error of 0.5 per cent. is frequently less than the distortion due to the method of printing and to changes from the humidity of the air. Only in southernmost Florida and Texas does this projection attain its maximum error of 233 per cent. The map measures 25 inches by 39 inches and will be sold by the Government at 25 cents.

Jan 7, 1919

By Samuel M. Brock

In recent years society has become increasingly concerned with maintaining and improving the quality of environment. Thus, public interest and concern with pollution problems is now high. This is reflected in recent federal and state efforts to formulate new legislation to prevent pollution and strengthen existing pollution laws. In reviewing literature pertaining to pollution problems, it is possible to distinguish many common elements. The most outstanding of these is the failure of the market to guarantee that private firms responding to price signals generated in the marketplace will make decisions leading to optimal resource use. Cases of market failure in allocating natural resources according to the wants of society frequently are due to the presence of technical externalities, or side-use effects.59 These roughly and generally can be defined as interdependencies among production and consumption units, the impacts of which are exerted other than through the market. They are, in other words, extra-market relationships. The economic unit generating external effects does not take them into account in decision-making. Thus, the tendency is for the unit to produce either more than society desires or not enough. In such cases society often has intervened in the decision-making process. This intervention frequently has taken the form of legislation to regulate production and consumption activities. Thus, a body of institutions, which acts as a constraint in decision-making processes, has materialized. These institutions are often far more influential in their effect upon resource use than are the forces of supply and demand acting in the marketplace. The problem of environmental pollution is essentially the problem of handling residuals which are the byproduct of all production and consumption activities which take place in the economy.2 These residuals are emitted into the air and water and disposed of on the land. They are interrelated, in that efforts to control emissions into the air or water can result in the production of solid wastes, which then present disposal problems. It is convenient to separate residuals by the type of pollution they cause-air, water, and land while remembering that these problems are related and that solutions may require coordinated effort.1 Residuals may be produced in both production processes and consumption. Residuals produced in production by the mineral industry, or firms utilizing its products, range from emission of sulfur dioxide by steam generating plants to radioactive mill tailings produced in the course of mining uranium.. Residuals associated with consumption are generated mainly through transportation of members of the household, space heating, and in the disposal of solid wastes, including refuse and junk autos. Residuals associated with both production and consumption receive attention in ensuing sections of this chapter.

Jan 1, 1976

By T. J. Bosworth

The effect of hydrogen pretreatment of alumina, magnesia, and zirconia crucibles on reduced oxygen levels in iron charges has been studied. Hydrogen treatment of commercial high-purity magnesia crucibles was observed to produce as high as 70 pct reduction in oxygen content in iron melts. Hydrogen treatment of the commercial high-purity grade zirconia crucibles produced a 25 pct reduction in oxygen levels in iron melts. An average reduction of Knoop hardness of 47 pct was recorded on the iron charges melted in hydrogen-treated crucibles. On the basis of the experiments and the free-energy diagram, it appears that the major source of reducible oxygen to the iron charge is the suboxides and impurity oxides rather than the major oxide of the crucible. Suitable pretreatment of the crucibles to reduce and remove these oxides yields low oxygen levels in iron melted in the crucibles. DURING the last decade, attempts to produce more pure and uniform alloyed metals have brought about the development of many new melting techniques. Notable among these are vacuum-induction melting, inert and consumable-electrode melting, the cold-mold technique, and numerous techniques for removal of impurities by chemical reaction. However great the achievements in this field, metals must still be melted in contact with media of varying reactivity; i.e., gas, ceramic, and slag. Studies have been made to attain an understanding of the reactions that take place during melting, including slag-metal reactions and equilibria, equilibrium of hydrogen and water vapor, and carbon dioxide and carbon monoxide with oxygen in molten iron. These reactions have been treated quite thoroughly. There is one condition, however, that has been widely overlooked, and, to the author's knowledge, only cursive investigation has been made of it. This is the reaction between the ceramic crucible material and the iron charge. In recent years, Hadley and Bianchi' made a series of studies on hydrogen deoxidation of iron in magnesia crucibles. Bianchi2 studied crucible-FeO equilibria in the temperature range 1525°to 1650°C in high vacuum with, however, inconsistent results. Richardson and Jeffes3 in their series of articles on thermodynamic reactions in the making of iron and steel refer to Wentrup and Hieber's4 work on iron and aluminum deoxidation. Their pork included melting iron in alumina crucibles and measuring the aluminum and oxygen content in the iron. Because of the low values obtained, question has arisen of their analytical accuracy.3 Dastur and chipman5 obtained values on hydrogen-oxygen equilibrium in molten iron contained in alumina crucibles similar to those obtained in experiments in the present program. Hochmann6 studied removal of impurities in chromium irons in high vacuum. His results with respect to oxygen level in chromium-iron melted in magnesia crucibles are consistent with results we have obtained.

Jan 1, 1959

By R. K. McGeary, B. Lustman

Orientation relationships and rates of annealing of 97 pct cold rolled zirconium have been studied by X-ray techniques, metallography, and by hardness measurements. The process of annealing occurring by the formation of domains, and their subsequent growth without recrystallization, is demonstrated. NUMEROUS investigators1-' have revealed sub-grain formation after annealing cold worked metal single crystals and have generally described the results in terms of a dislocation mechanism of polygonization.5,6 in heavily cold rolled polycrystal-line aluminum the first stages of heating cause an apparently spontaneous subdivision of regions of the deformed matrix into a great number of slightly disoriented domains followed or accompanied by rapid growth of certain domains to form a recrystallization texture.7,8 In the present investigation the isothermal rate of annealing of cold worked polycrystalline zirconium has been studied by X-ray techniques, metallography, and by hardness measurement. It will be shown that, rather than by the usual nucleation and growth mechanism,"12 the process of annealing can best be explained by the formation of domains early in the annealing treatment and the subsequent growth of these domains without recrystallization. Experimental Procedure All the experimental work was performed on an arc-melted ingot of high purity zirconium crystal bar made by Westinghouse in a production scale deBoer unit. The weight percentage of impurities in the zirconium were as follows: C, 0.04; Fe, 0.05; Hf, 0.014; W, 0.01; Ti, Ni, and Al, 0.003; Si and N, 0.002; Cr and Cu, 0.001. Metallographically the zirconium showed only a single phase. The 4 in. diarn ingot was forged at 760°C to a 1 1/2x3 in. plate and was then rolled at 760°C to 0.150 in. thickness and annealed at this temperature for 20 min to produce an equiaxed grain structure of about 0.1 mm average grain diameter. The hot rolled plate was roller-leveled, surface ground to 0.135 in., cold rolled 83 pct reduction in thickness on a two-high mill, and then to a total reduction of 97 pct on a Sendzimir mill. The 0.004 in. strip material so produced received no subsequent mechanical treatment. Specimens % in. square were sheared from the rolled strip and isothermally annealed at 104 mm Hg in an all glass vacuum system equipped with a Vycor furnace tube. The temperature data presented are the average temperatures during the runs and did not vary more than about k3"C. X-ray Diffraction Methods: When zirconium is drastically cold rolled, a high degree of preferred orientation results in which prism poles, {1010}, are perpendicular to the rolling direction. After fully annealing this material an entirely new texture develops which corresponds to a 20" or 40" rotation of the deformation texture about hexagonal axes of

Jan 1, 1954

By Carl Tolman, LeRoy Scharon, Harold Powers

THIS paper presents geophysical and subsurface data observed in the vicinity of Shafts No. 1 and and 5 of the National Lead Co. lead mines at Fred-ericktown, Madison County, Missouri, see Fig. 1. The area selected is an excellent example to illustrate the close correlation between geophysical data and geological facts as revealed by drilling and mining. Such close correlations make geophysical applications appropriate to the development of known ore-bodies as well as the exploration for new orebodies. In the past, magnetic and shallow electrical resistivity observations were made over limited areas in the Fredericktown lead district by the Missouri Geological Survey, with favorable results. The first extensive magnetic and electrical resistivity surveys were started by the U. S. Bureau of Mines in May 1945 in two areas located northwest and southwest of Fredericktown, as shown in Fig. 1. The results of these surveys were reported in April 1948 at Denver, spontaneous-polarization surveys were made over the property of the St. Louis Smelting and Refining Co. at Fredericktown by Sherwin F. Kelly Geophysical Services, Inc. Aeromagnetic surveys were completed in 1948 over the Fredericktown quadrangle by the U. S. Geological Survey. Since 1945 geophysical surveys have been an important part of exploration programs in the Fred- ericktown district. Such methods, magnetic and electrical resistivity, are now serving as guides in the further development of known orebodies. On an irregular pre-Cambrian igneous erosion surface Lamotte sandstone of upper Cambrian age was deposited, partially filling the topographic basins, see Fig. 2. Above and conformable with the Lamotte sandstone lies the Bonneterre formation, a dolomite with locally interbedded thin dolomitic limestones and shales at its base. This formation also only partially filled the topographic basins. The Bonneterre was overlain by the Davis, Derby, Doe Run, and Potosi formations, which are principally dolomite. Uplift, tilt, and slight warping has allowed erosion and weathering to remove most of the sediments overlying the Bonneterre, and in many places, not far from the mine, the Lamotte sandstone is exposed. This erosion has also exposed areas of pre-Cambrian igneous rock. The Lamotte sandstone, having been deposited on an irregular pre-Cambrian surface, is extremely variable in thickness and ranges from zero where it laps the pre-Cambrian rocks to 250 ft thick in the deeper basins. In the vicinity of the mines the Bonneterre dolomite ranges from zero where it wedges out against the pre-Cambrian igneous rocks to 400 ft thick. The ore deposits occur as a bedded disseminated type1 and are chiefly composed of galena and pyrite with minor amounts of chalcopyrite and siegenite. Heavy pyrite and marcasite mineralization may be found throughout the Bonneterre formation. However, there is little or no apparent association of these iron sulphide bodies lying above the ore hori-

Jan 1, 1954

By R. T. DeHoff

A new approach to the measurement of the size distribution of particulate structures imbedded in opaque bodies is developed. The method is based upon the assumption of a general two-parameter distribution curve, and the estimation of these two parameters from three well-known counting measurements made upon metallogvaphic sections. The total number of particles in the system is also a product of the analysis. Application of the method with the assumption of the logarithmiconorma1 disfribution function is developed in detail. A complete description of the geometry of a particulate structure requires the determination of the size distribution of particles. The problem of estimating the size distribution of particles of a particular phase in a multiphase system, or the grain-size distribution in a homogeneous system, has been approached by many investigators.'-'0 All of the solutions proposed by these investigators share the following characteristics. a) A minimum of several hundred particle sections in the microstructure must be examined, and some characteristic dimension recorded, such as area,3'5 intercept length,6"9 or diameter.1'2'4'10 b) The resulting data must undergo a series of fairly complex calculations to generate the empirical histogram which describes the size distribution in three dimensions. c) In order to manipulate the result, the histogram must be fitted to some assumed mathematical formula, using the attendant statistical procedures. d) With two notable exceptions,8,10 the particles must be spherical. The measurements and calculations involved are in general very tedious and time-consuming, with the logical result that much effort has been expended in the development of equipment which will perform these tasks automatically and semiautomati-cally.9,11-15 considerable success has been achieved in this area, but the equipment is in general expensive, and usually places stringent requirements On the quality of microstructure which can be reliably analyzed. In laboratories which do not possess such equip- ment, the analysis of geometry is usually limited to measuring total properties of the microstructures, such as volume fraction and interfacial area, because the measurements required are much simpler to make. The determination of size distributions rarely is undertaken. The development which is presented in this paper permits the estimation of size distributions of three-dimensional structures from the same simple counting measurements which are required to determine the surface area and volume fraction of the particulate structure, and one other counting measurement. The basic approach that is used is to assume a general mathematical form for the distribution, which is described by two parameters (as the normal distribution is described by assigning values to the mean and the standard deviation), and then estimate these two parameters from the results of the counting measurements. The introduction of a third counting measurement also permits the evaluation of the number of particles per unit volume, Nv.

Jan 1, 1965

By J. F. Wolff, Anson A. Betts

The following correspondence relating to a paper bearing the above title, presented by J. F. Wolff, at the New York meeting in February, 1917, and published in the Transactions, Volume LVI, page 142, has passed between the author of the paper, and Mr. Anson G. Betts, and is interesting, although it was received much too late for incorporation in its proper place in Volume LVI. Anson G. Betts, Asheville, N. C.—1. I should like to ask Mr. Wolff if he finds from analysis of the iron formation and of the iron ore, and from the relative amounts of each in each unit area of the formation, unleached and after leaching, that the iron remains entirely insoluble and the total quantity still remains present; or whether he finds that some of the iron is removed, or possibly even added by deposition from the water passing through the formation. 2. The water that passed into the iron formation had to go somewhere; was it absorbed by underlying formations through hydration, or, after passing through the ore formation, did it come to the surface in springs at a lower elevation, or how did it escape from the ground? 3. I should like to ask Mr. Wolff whether he finds that the iron formation in the sedimentary series does not come next to the quartzites and generally between the quartzites and slates. J. I?. Wolff, Duluth, Minn.—1. In common with others, you appear to have some hesitancy in accepting the fact of the removal, by solution, of the enormous quantity of silica which has been leached out of portions of the Biwabik iron formation, thus forming orebodies of merchantable iron ore. I believe that even Dr. Waldemar Lindgren once hesitated to accept this fact. However, the evidence is so simple and absolutely conclusive that the fact is established beyond all question. At the contact of orebodies with their rock walls, the bands of iron ore in the orebody can be seen in contact with the corresponding bands of original iron oxide in the rock wall, and the chert layers in the rock wall can be seen to give place to fine granular material (fine silica and iron oxide) and pore space. This is especially noticeable where slumping at the rock walls has not been so great as to displace the layers in the orebody from their contact with their corresponding layers in the rock wall. Although complete analyses of the entire original rocks in the iron series have not been made in any place, to my knowledge, from the best data at hand as to the average analysis of the Biwabik series and the

Jan 1, 1920

By John F. Elliott, John R. Rawling

The rate of reduction of silica to silicon by carbon at 1550° to 1700°C in iron blast-furnace type slag-metal systems has been investigated. In the tower portion of the temperature range oxygen transport in the metal boundary layer at the slag-tal interface is probably rate limiting. A second step, which apparently involves a chemical process in the slag at the slag-metal interface, appears to be rate limiting when the oxygen-transport limitation is avoided. Above 1650°C rate control of the reduction by carbon probably is mixed between the two steps. INVESTIGATIONS1.2 into the equilibrium distribution of silicon between graphite-saturated slags and metals typical of iron blast-furnace practice show that, under the experimental conditions specified, the reduction of silica to silicon is relatively slow compared with the rates of other slag-metal reactions under similar conditions. For this reason, the reduction of silica in blast-furnace slag-metal systems was considered to be an interesting subject for further study. Investigations of the kinetics of the reaction3-5 suggest that several possible steps may be rate controlling, and that the rate-controlling step depends not only on the physical state of the systems but also on the configuration of the apparatus. The main objects of the investigation reported here were to sug- gest plausible reaction paths for the reduction of silica under the experimental conditions chosen and to determine the step or steps which control the rate of reduction of silica. EXPERIMENTAL Two types of experiments involving the reduction of silica from the slag were carried out. In the first, the only reducing agent present was carbon (graphite), for which the over-all reaction is (SiO2) +2C(gr) —Si + 2Co(g) [l] The second type was a graphite-saturated ferro-silicon-iron concentration cell. In it silica in the slag could be reduced either by carbon according to Eq. [I], or by a reaction of electrochemical nature in which silicon was oxidized at the ferrosilicon-slag interface and silica was reduced at the slag-iron interface without the formation of CO. The two types of experiment are described below. Reduction of Silica with Carbon as the Only Available Reducing Agent. The reduction of silica was accomplished by allowing a liquid lime-alumina-silica slag and graphite-saturated iron to react in an induction-heated graphite crucible. The crucible was 2.25 in. diameter and 5 in. deep; it was fitted with a graphite stirrer which penetrated through the slag and into the metal, Fig. 1. The slag and metal charges weighed 350 g each. Pure carbon monoxide at a pressure of 1 atm was maintained above the melt by passing the purified gas through the crucible at a rate of 0.5 liter per min. The gas did not stir either the slag or metal. Temperature measurements were made by sighting an optical pyrometer down the hollow stirrer rod into a 1/4-in. hole drilled in the stirrer blade. The crucible temperature was maintained within *15"C of the required value by manual control of the power supply to the

Jan 1, 1965

J. W. Tomlison—It seems probable that the author's conclusion, that the conductivity of the slags decreases with increasing content of FeO, is erroneous due to the method of plotting the data. Thus, the results of other workers2,3,13,15 show that the conductivity of molten oxide slags increase with increasing temperature, indicating that the trend of the curve shown by the authors is due to the fact that the data for the slags containing relatively small amounts of FeO are at higher temperatures than those for the slags containing relatively large amounts of this oxide. In this connection the work of Wejnarth2 may be mentioned in which in an investigation of a series of iron silicate slags, the conductivity was found to increase with increasing content of FeO; the fact that the author's slags contained TiO2 probably does not affect the issue since it has been shown15,16 that, at least as far as conductivity is concerned, this oxide behaves essentially the same as silica and that mixtures of the oxide with silica have a very low conductivity of the order of 10-4 mhos at 1750°C. In connection with the experimental technique it may be noted that bubbles of carbon monoxide would probably be produced at the surface of the graphite electrodes in contact with the melts thus rendering the accuracy of the measurements somewhat open to question. J. L. Wyatt (author's reply)—Dr. Tomlinson makes reference to works by Martin and Derge, which indicate that slag systems containing no TiO2 are characterized by an increase in conductivity with an increase in temperature. Further, I have cited his examples, which indicate a drastic increase with small temperature change. The results of Dr. Derge's work have no bearing whatsoever on the results of this paper, since the slags under study here contained up to 70 pct TiO2 One cannot generalize on slag systems as a whole on the basis of any one family, for there are definite compounds of ionic nature formed in each system, and the ionic mobilization of these is something that cannot be determined without actual experimentation. Dr. Tomlinson makes reference to an unpublished work which, he claims, shows that titanium dioxide behaves the same as silica in regard to conductivity. Since I have not had 'an opportunity to see the paper I cannot make any comments, but unless the same slag system was studied there can be no specific comparison of results. If the decrease in conductivity of the slag was due entirely to temperature phenomena, as Dr. Tomlinson indicates, then one is without an explanation of the values shown in the paper for slags containing from 10 to 20 pct FeO. I cannot agree that the deviation in findings was appreciably related to temperature change; further, I believe this point was completely covered in the paper. References 13 Endell and Hellbrügge: Glasstech. Ber. (1942) 20, 277. 14 Bockris, Kitchener, Ignatowicz and Tomlinson: Faraday Society. Discussion (1948) 4, 265. 15 Tomlinson: Thesis, London 1949. 10 Bockris, Kitchener, Ignatowicz, and Tomlinson: Unpublished work.

Jan 1, 1951

By J. L. Wyatt

J. W. Tomlison—It seems probable that the author's conclusion, that the conductivity of the slags decreases with increasing content of FeO, is erroneous due to the method of plotting the data. Thus, the results of other workers2,3,13,14 show that the conductivity of molten oxide slags increase with increasing temperature, indicating that the trend of the curve shown by the authors is due to the fact that the data for the slags containing relatively small amounts of FeO are at higher temperatures than those for the slags containing relatively large amounts of this oxide. In this connection the work of Wejnarth2 may be mentioned in which in an investigation of a series of iron silicate slags, the conductivity was found to increase with increasing content of FeO; the fact that the author's slags contained TiO2 probably does not affect the issue since it has been shown15,16 that, at least as far as conductivity is concerned, this oxide behaves essentially the same as silica and that mixtures of the oxide with silica have a very low conductivity of the order of 10-4 mhos at 1750°C. In connection with the experimental technique it may be noted that bubbles of carbon monoxide would probably be produced at the surface of the graphite electrodes in contact with the melts thus rendering the accuracy of the measurements somewhat open to question. J. L. Wyatt (author's reply)—Dr. Tomlinson makes reference to works by Martin and Derge, which indicate that slag systems containing no TiO2 are charac-terized by an increase in conductivity with an increase in temperature. Further, I have cited his examples, which indicate a drastic increase with small temperature change. The results of Dr. Derge's work have no bearing whatsoever on the results of this paper, since the slags under study here contained up to 70 pct TiO2. One cannot generalize on slag systems as a whole on the basis of any one family, for there are definite compounds of ionic nature formed in each system, and the ionic mobilization of these is something that cannot be determined without actual experimentation. Dr. Tomlinson makes reference to an unpublished work which, he claims, shows that titanium dioxide behaves the same as silica in regard to conductivity. Since I have not had 'an opportunity to see the paper I cannot make any comments, but unless the same slag system was studied there can be no specific comparison of results. If the decrease in conductivity of the slag was due entirely to temperature phenomena, as Dr. Tomlinson indicates, then one is without an explanation of the values shown in the paper for slags containing from 10 to 20 pct FeO. I cannot agree that the deviation in findings was appreciably related to temperature change; further, I believe this point was completely covered in the paper. References 13 Endell and Hellbrügge: Glasstech. Ber. (1942) 20, 277. 14 Bockris, Kitchener, Ignatowicz and Tomlinson: Faraday Society. Discussion (1948) 4, 265. 15 Tomlinson: Thesis, London 1949. 10 Bockris, Kitchener, Ignatowicz, and Tomlinson: Unpublished work.

Jan 1, 1951

By S. J. Hubbard, S. D. Michaelson, A. W. Last, B. H. Ensign

Of the seventeen western states, five-Arizona, Utah, New Mexico, Montana, and Nevada-produce about 90 pct of this country's primary copper. All seventeen of these states occupy 60 pct of the nation's land area but receive only 25 pct of the country's total precipitation. Seventy percent of this precipitation returns directly to the atmosphere through evaporation and transpiration, leaving very little for ground reservoir recharge or immediate domestic, agricultural, or industrial use. With so limited a supply available for all, competition for water rights among users is severe. The result does not always permit using the limited supply to produce the most valuable end product. Most of industry and much of agriculture can shop around for suitable operating locations. Where water is critical to their purposes, they can and do locate in areas where the needed amounts are available. Such is not the ordinary lot of the mining industry, which must locate in the area of the deposit it is planning to mine and concentrate. In the case of copper this happens to be, for the most part, right in the heart of the semi-arid regions of the West.

Jan 7, 1960

By K. Kobayashi, K. Ueda, K. Yamaguchi

Lead concentrates from Kuroko (black ore) mines, which contain 4-7% Cu, 55% Pb, 3-777, Zn, and 0.5-0.9% As, are pretreated by a hydrometallurgical process before electric furnace smelting with other lead resources from Kuroko. The hydrometallurgical pretreatment involves sulfuric acid leaching in the first stage and ferric leaching in the second stage. This paper describes the short history of lead recovery from Kuroko and the performance of laboratory tests and pilot plant and commercial operations.

Jan 1, 1985

By A. D. Hodges

The process to be described, whatever other merits (or demerits) it may have possessed, certainly proved a financial success under the conditions of the locality where it was introduced and where a refining process had been sought previously in vain. I have ventured to bring it to the notice of the Institute in the hope that it may prove of some interest as a solution of a practical problem, such as is often presented to the metallurgist in the remote mining regions of the West. The method was used first at the Lyon Mill at Dayton, Nevada, and has been adopted at other tailings-mills on the Cornstock. These mills treat two classes of tailings: "sand," or; material which has passed previously through the pans of the ore-mills; and " slimes," or the fine clayey material which, coming from the battery, is too light to settle in the tanks inside of the mills but is

Jan 1, 1886

By B. B. L. Seth, H. U. Ross

A generalized rate equation for the reduction of iron oxide was derived from which two particular equations were obtained: one for rate controlled by the transportation of gas, the other for rate controlled by the phase-boundary reaction. Pellets of pure ferric oxide having diameters of 8.5 to 17.5 mm and a density of 4.8 g per cm3 were prepared and reduced by hydrogen at 750° to 900°C. From the analysis of data obtairzed, it was observed that neither the phase-houndarv reaction nor the transportation of gas controlled entirely the rate of redziction. Rather, the mechanism of reduction can he divided into three stages. In the beginning, the process seems to depend predominantly on the surJrce reaction, hut after a layer of iron is formed the diffusion of gas becomes the controlling factor. Towards the end, however, the rate falls sharply due to a decrease in porosity. The times predicted by the generalized equation for a certain degree of reduction showed an excellent agreement with those obtained experinmentally for pellets of varying sizes. WIDE interest in iron oxide reduction has resulted in many valuable studies pertaining to thermody-namical properties, equilibrium diagrams, and chemical kinetics. Although the thermodynamical properties and equilibrium diagrams are now known with a fair degree of accuracy, the mechanism and rate-controlling step in the reduction of iron oxides presents a problem to research workers which is still unsolved. This is because the field of chemical kinetics is so highly complex. Besides the chemical reaction between oxide and reducing gas, several other processes are occurring simultaneously such as solid-state diffusion of iron through intermediate oxides (FeO and Fe3O4), the diffusion of reducing gas inwards and of product gas outwards, and the sintering of iron if reduction is carried out above the sintering temperature of iron. Furthermore, there is a large number of variables, including the nature and flow rate of the reducing gas, the chemical composition and physical properties of the ore, the temperature of reaction, particle size, and so forth, all of which can affect both the mechanism and the kinetics of reduction. Despite the controversy and diversity of opinion about the mechanism of iron oxide reduction, three main schools of thought have emerged. According to the first, the rate is controlled by the diffusion of gas through the boundary layer of stagnant gas; the second claims that the rate is proportional to the area of the metal-oxide interface, while the third believes the transportation of reducing gas from the main stream to the metal-oxide interface and of product gas from the metal-oxide interface to the main stream to be the rate-controlling step. 1) The boundary-layer theory is true mainly for packed beds where the flow of gas through the bed is important. For a single particle, the boundary layer may be prevented from being the rate-controlling step if a gas flow rate of reducing gas above the critical flow rate is used. 2) Several workers have reported a linear advance of the Fe/FeO interface which provides excellent support for the belief that reduction is controlled by the surface area. McKewanl has given formal shape to this concept with mathematical derivation and has shown it to be valid for reduction of several iron ores, hematite, and magnetite, both by H2 and H2, H2O, N2 mixtures. Some other investigators, however, do not find this theory to be entirely valid. Deviations have been observed2 and further confirmedS3 Hansen4 also agrees that deviations do occur, at least in the latter stages of reduction, while from the data of several investigators summarized by Themelis and Gauvin,5 it is clear that the theory is not always applicable and further that, when it is applicable, it does not hold in the final stages of reduction. 3) Among those who claim the transportation of gas to be the rate-controlling step are Udy and Lorig,6 Bogdandy and Janke,7 and Kawasaki el a1.8 The validity of the theory has also been acknowledged indirectly by other research workers who show that the sintering and recrystallization of iron cause a decrease in reduction rate, for it is only if the transportation of gas is important that this sintering has any bearing. However, the theory has been rejected by some because they have failed to obtain

Jan 1, 1965