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By Utley Wedge

In general, the art of securing copper from sulphide ores or concentrates may be said to consist of: (1) separation, in the molten state, of copper sulphide with some iron sulphide, from the great bulk of gangue-material, followed by (2) elimination of sulphur and iron from the molten matte, by oxidation and fluxing, leaving metallic copper. The definition is made broad enough to cover the general practice, whether or not the ore or concentrate is given a prelimiuary roast for the removal of surplus sulphur. The above process, which I will designate as the smelting process, makes necessary the presence in the ore, or the addition thereto, of such silica, lime, and iron as may be necessary for the formation of a light and fusible slag, together with sufficient sulphur and iron for the formation of copper-matte, and also the addition to the matte of sufficient silica for the oxidation and fluxing-out of the iron. These items, together with the cost of fuel sufficient for melting the mass, constitute important items of cost in the copper-smelting process. Numerous cases where fluxing-materials are scarce or dear, or where fuel is expensive, have caused special attention to be given recently to the wet process of copper-extraction, which may be designated as consisting of forming soluble copper salts which are then washed or leached out of the ore or concentrates by dissolving in water or acid. Metallic copper may then be secured from the solution of copper salts by electrolysis; by cementation; or copper can be brought out of the solution as a hydroxide or other insoluble precipitate and reduced to metallic copper by subsequent melting in a reducing atmosphere.

Jan 1, 1913

By Nathaniel Herz

PARTING of bullion before shipment to the mint had been considered by the Homestake Mining Co. at various times, but had never been attempted before 1933, be- cause the margin of profit appeared to be too small to warrant the complications in refining. When the gold standard was abandoned by the United States in the spring of 1933, however, parting of the bullion was decided upon. The method selected was the Miller or chlorine process, which consists of the passing of gaseous chlorine into a bath of molten bullion, converting all metals other than gold into chlorides, and remov-

Jan 1, 1935

By MAURICE ALTMAYER

M Y DUTIES, as a member of the Department of Franco-American War Cooperation of the French High Commission were to study the copper and brass industries of America from the mining of the various non-ferrous metals to the semi-finished, or finished materials. In the pursuit of these studies, it was my privilege to visit a number of industries and organizations in different parts of the country. I first visited most of the Eastern copper refineries that were supplying the Allies with vast amounts of metal. These works are producing their material by the multiple or the series process, although the first method predominates. But, regardless of the process employed all the plants attain an exceptionally high standard of quality in their production. One of the points that particularly attracted attention was the manner in which improvements could be traced from the older worlds to the more recent ones. The impression was that, thanks to a spirit of broad-minded cooperation between the principals of the companies and frequent exchanges of views between members of the staffs, all persons interested benefitted by the experience thus gained, to the advantage of the community at large.

Jan 1, 1920

By F. Ernest Brackett

Much new data on the flow of gases have been discovered by recent experiments by the United States Bureau of Mines and others. Although additional investigation is still desirable, the information now collected seems sufficient to attempt a tentative coördination of the friction factors. This study is confined entirely to fluid friction when the density throughout the duct is so nearly constant that it may be so considered. In the subsequent discussion the following notation is used: v = mean velocity of fluid in duct, feet per second. v' = mean velocity of fluid in duct, meters per second. R = hydraulic radius of duct, feet. R' = hydraulic radius of duct, meters. S = the hydraulic slope. P = pressure absorbed by friction, pounds per square foot. p = pressure absorbed by friction, pounds per square inch. p' = pressure absorbed by friction, kilograms per square centimeter. A = sectional area of duct, square feet. O = perimeter of duct, feet. L = total length of duct, feet. L' = total length of duct, meters. d = diameter of a cylindrical duct, inches. w = density of the fluid, pounda per cubic foot. g = specific gravity of the fluid compared with water = w % 62.4. C, k and B, coefficients for formulas using English measures. C' = metric coefficient, v' = C'R'S. n = coefficient of roughness for English or metric units. The basic formula for the flow of all fluids at constant density appears in the three following forms, which may be denominated: (a) The slope formula, v = CRS (b) The ventilation formula, " n = (c) The pipe formula, C is Kutter's coefficient, which is extensively applied to the flow of water in ducts and channels of all kinds; E is Atkinson's coefficient, used principally with air in ventilation problems; B is a coefficient conveniently adapted to studying the flow of water, gases and vapors in pipes. 312

Jan 1, 1927

By C. K. Leith, W. J. NEAD

(Glen Summit Meeting, June, 1911.) . ONE Of the most significant developments in the iron industry in recent years has been the discovery and opening of enormous reserves of low-grade ore in eastern and northeastern Cuba. The two principal fields are the Mayari and the Moa, situated on Nipe bay, in the Province of Oriente. A less well-known district of the same type is that of Baracoa, at the east of the island, and another is in Camaguey province in central Cuba. In the comprehensive estimates of the iron-ore reserves of the world, published during the summer of 1910 by the International Geological Congress in Sweden,' these Cuban deposits are estimated at about 2,000,000,000 tons. Certain it is that the reserve is a large one. The Spanish-American Iron Co., the Juragua Iron Co. (Bethlehem Steel Co.), the U. S. Steel Corporation, and others have been active in this exploration.. The Spanish-American Iron Co. has established a port for the handling of these ores at Felton, has built a railway 16 miles to the ore-fields, and has opened up deposits for steam-shovel mining. Its expenditures have reached an aggregate of about $6,000,000 in preparation for the handling of these ores. Shipment of the ore to Sparrow's Point, Md., has begun and may be expected to rise to a considerable amount in the near future. The ore reaches this point at a cost per unit of iron considerably lower than Lake Superior ores, and the presence of a low percentage of nickel gives a desirable steel. It is not the purpose of this article to consider these ores from a commercial stand-point, but rather to discuss their-origin. If our conclusions are correct, they throw light on the character of the deposits which should have some commercial significance. 1 The Iron Ore Resources of the World, an inquiry made upon the initiative of the Executive Committee of the Eleventh International Geological Congress, Stockholm, vol. ii., p. 795 (1910).

Mar 1, 1911

By O. B. Buchlen, J. W. Smith

The Coal Research Bureau of the School of Mines at West Virginia University, using an experimental flotation cell designated an airlift-cyclone was able to obtain a clean coal product containing 7.64% ash with 94% yield and 97% coal recovery. This favorable performance was obtained with the experimental flotation cell operating as a simulated three-stage unit on slurry taken from the fine coal circuit of a coal preparation plant. This experimental device, consisting of a sheet metal cyclone-like unit mounted on a U-shaped uplift pipe, uses a combined flotation and cyclone action to beneficiate the minus 14 mesh partially cleaned feed product. In addition to providing comparable analytical results, the airlift-cyclone possesses other attractive features among them being a low capital expenditure, utilization of moderate plant floor space, efficient operation on high density feed slurry, and absence of moving parts. The primary shortcoming of the experimental cell is its limited capacity. The Coal Research Bureau presently has under construction a larger unit which, it is hoped, will provide the capacity and quality to establish the airlift-cyclone as a commercially feasible unit. Froth flotation of fine coal is a practice which has only recently gained wide acceptance in this country. Various explanations can be put forth for this delayed acceptance of a very selective and efficient system of coal preparation. Among these reasons would be the advent of continuous mining machines resulting in the increased production of coal fines, the change in market patterns from domestic and rail consumers who did not want fines to a predominantly utility market which normally consumes fines, and also the imposition of legal restrictions in regard to stream pollution. However, the major detriment is probably the high cost involved both in installation and operation of the flo- tation unit and auxiliary systems. These facts assume greater emphasis when considering that froth flotation installations normally process a low quality feed product. A recent estimate' of installation costs including dryers, filters, and other auxiliary equipment for a flotation system was $5000 to $7000 per ton of capacity while the operating costs, exclusive of auxiliary equipment, were estimated at 10 to 306 per ton of feed. The Coal Research Bureau of the School of Mines at West Virginia University is currently developing a simplified froth flotation cell, designated an airlift-cyclone, which may provide considerable savings in capital and operating costs without sacrificing product quality or recovery. This experimental cell consists of three primary components: 1) a vertically mounted U-shaped pipe; 2) an air injector device; and 3) an integrally mounted cyclone-like unit (Fig. 1). A feed slurry is introduced at the top of one leg of the U-pipe while compressed air is injected near the base of the other leg. The air serves both to aerate the pulp and to cause it to flow upward into the base of the cyclone unit where the floated clean coal is separated from the reject material and unfloated coal which remains in slurry. The Coal Research Bureau's experimental airlift-cyclone is somewhat similar in principle to a flotation device developed by Russian engineers in the late 1950's. In tests upon a two-stage pilot-size device, the Russians obtained very favorable cleaning efficiencies.' However, later experience with production models demonstrated that rated capacities and acceptable product quality could not always be maintained.3 Because of these limitations, Russian engineers subsequently recommended that conventional, mechanical cells be used when cleaning difficult to float slurries. Engineers at the Coal Research Bureau felt that such a device utilizing the combined actions of a cyclone and a froth flotation machine offered numerous attractive features and merited investigation. Accordingly, a small capacity experimental airlift-cyclone was designed and, with the permission of the Christopher Coal Company Div. of Consolidation Coal Co., installed in Christopher's Humphrey preparation plant near Morgantown, West Virginia.

Jan 1, 1964

By AIME AIME

COAL occupied a large place in the technical sessions of the Institute at its annual meeting for in addition to three sessions specifically de- voted to coal the two sessions on mine ventilation and the two on ground movement and subsidence, which are reported under their own headings, were primarily concerned with coal. The first session on coal was a joint one with the Iron and Steel Division, on Wednesday afternoon, with F. H. Crockard and J. R. Campbell presiding as joint chairmen and the latter actually officiating. The principal topic of discussion was G. S. Scott's paper "Evaluation of Coal for the Making of Blast- Furnace Coke," which has been published as T. P. 159. The author made a brief statement of its con- tents to start the discussion and the chairman, after briefly reviewing it himself, called on C. A. Meissner to start the discussion. He briefly reviewed the economic factors in the use of coal for coke-making, saying that not only .does the removal of 1 per cent of ash from the coal reduce the cost of pig iron 12 or 13c. per ton, but it also permits coke of satisfactory structures to be made from a coal which otherwise could not be used. He stressed the importance of uniformity in blast-furnace fuel and discussed the benefit of mixing different coals as raw material for the coke oven and cited experience with Illinois coals.

Jan 1, 1929

Insoluble slimes are present in nearly all sylvinite ore bodies and must be removed prior to potash flotation because they adsorb excessive amounts of potash flotation reagents and cause low potash recoveries and grades. The problems associated with insoluble slimes will become more pronounced as high grade-low insol potash ores are depleted and lower grade ores containing high insols are processed. The most common commercial practice for insoluble slimes removal is mechanical desliming (hydroclassification); however, most of these desliming circuits were designed to treat sylvinite ores containing less than 4 percent insoluble slimes. As Mr. Banks mentioned in his presentation, higher insoluble slimes concentrations (>4 pct) in the mill feed overtax the mechanical desliming circuit and result in excessive brine and potash losses. Increasing the capacity of the circuit would require redesigning of the entire potash circuit and additional costly equipment. Because of mineralization and liberation properties of the high insols sylvinite deposits, the expansion of the desliming circuit may not economically maintain high potash grades and recoveries. Selective flocculation-flotation is an excellent alternative for removing insoluble slimes from potash ores. Cominco's ore, containing 4.5 to 8 percent insoluble slimes, is particularly amenable to the slimes flotation process, probably because of the absence of expanding-type clays such as montmorillonite. The overall potash recovery of 86 percent and low slime flocculant and collector dosages of 0.03 to 0.04 pound reagent per ton of feed is good evidence of the success of the process. If appreciable montmorillonite were present, the metallurgy would not be as favorable and reagent consumptions would increase significantly.

Jan 1, 1979

By G. A. Vissac, R. G. Minet, N. E. Sylvander

R. G. Minet—The authors' description of the remarkable progress made in the last few years in applying the fluidized solids technique to the problem of lignite drying and carbonization clearly demonstrates that engineering techniques available today may make many processes practical and profitable which a few years ago were considered otherwise. As pointed out in the article, the future of the carbonization step hinges on the value and utilization of low temperature tar. On paper, at any rate, this tar looks like a valuable raw material for the chemical industry to use. Some 50 to 60 pct may be converted to pitch for electrodes, roofing, road tars, and other valuable products; the 25 to 30 pct tar acids could conceivably form a basis for a new low cost resin or plastic of the phenolformalde-hyde type. Yet these materials are so new and dissimilar from available sources that much work must be undertaken by the chemical industry before they will be accepted. Now that the work of Dr. Perry and his colleagues has made a large supply of low temperature tar a real possibility, I would expect the chemical industry to accelerate its work in this field. On the basis of certain data available in the literature it appears possible to produce a more aromatic tar, although in smaller yield, by operating at temperatures in the range of 1300" to 1500°F. Operating a fluidized bed process for lignite at these conditions should be technically possible, at least, and could produce a tar having more familiar characteristics. I wonder if Dr. Parry would care to comment on such a possibility. Incidentally, in our own work on carbonizing coking coals in fluidized beds, using Ohio, Pennsylvania, and West Virginia high volatile bituminous coals, we have obtained yields which agree with the correlation given for tar yields vs moisture and ash-free volatile Btu. Our data are slightly under the line, but certainly in the range of the correlation. We have also obtained evidence in support of the authors' statement as to the effect of air on the process. In our pilot plant all the heat required for carbonizing is released by internal combustion of char in the fluidized bed in normal operation. We are also equipped to obtain all carbonization heat by external electric heaters on the shell of the carbonizer while introducing only an inert gas to the process. We note no difference in tar yield or characteristics between the two operations. In the case of the gas, however, it appears that some hydrogen is consumed by the air combustion. We would be interested in hearing in a little more detail about the hot dust and char handling problems at Sandow. Have the authors found char subject to spontaneous combustion? Have they ever tried a coking coal in their pilot plant? V. F. Parry (author's reply)—Production of a more aromatic tar by operation of the carbonizer at 1300" to 1500°F does not appear to be economical. 1) The capacity of a reactor operating at 1500°F would be 30 to 50 pct less than the capacity at 932 °F and the cost of processing would increase materially. 2) The cracking of tar vapors in a reactor requires appreciable time to complete the reactions and it is doubtful that considering the very short time of residence of tar vapors within the reactor (4 to 10 sec after evolution) the basic character of the tar would be changed significantly. This is indicated from the data reported in Table XIV. 3) General studies have shown that it is advisable to operate at the minimum temperature to produce the maximum tar and minimum gas. 4) Operating problems and the maintenance of vessels and reactors, and the hazards of handling hot char, increase with the temperature of carbonization. It is technically possible to operate at temperatures as high as 1500°F, but in my opinion it is not economical or desirable. We believe that the primary tar must be won in the simplest way and then processed alone to change its character for production of desired products. It is interesting to have confirmation of our observations on the reaction of air with the products of carbonization. The major reaction is with the char, fol-

Jan 1, 1957

By Stewart Coleman, Thomas W. Moore, H. D. Wilde

It is recognized that in the early days of the petroleum industry oil was produced with practically no scientific or fundamental knowledge of the laws and principles governing its extraction from the ground. Only a few, if any, of those exploiting the oil resources made any effort to collect accurate scientific information. There was little need for it, for as is frequently the case where the supply of a natural resource appears inexhaustible and is greater than the demand, large profits were possible from merely skimming the surface with little regard to the efficiency or thoroughness with which the oil was obtained. With this policy in force, great quantities of gas were wasted and when the reservoirs ceased producing by natural means they still contained a large fraetion of the oil originally in them. The present tendency in the industry is toward conserving existing oil reserves. In order that greater percentages of the oil present in the ground may be recovered, efforts are being made to improve production methods and to rework depleted fields. If the production methods are to be improved intelligently it is essential that the fundamental laws be known and understood, consequently large amounts of money and effort are being spent in gathering data that will serve to define and interpret these laws. A great deal of attention is being focussed on the study of the motion of oil through an oil-bearing sand, the forces that cause it to move and the factors that affect its motion. It is recognized that one of the important factors is pressure, but its quantitative effect is not known. In a given field the rate of production declines with time and so does the rock pressure. Furthermore, a comparison of different fields shows, as a

Jan 1, 1930

By William F. Boericke

CONSIDERABLE waste of oil and grease in lubricating motors and other machinery results from the use of bearings that are not totally enclosed. There is also the likelihood of damage to the bearing through the accidental introduction of grit or dust both in the oiling process and after, unless the cover is entirely dustproof. With the ordinary sleeve bearing that is only partly enclosed, it is generally easier for a careless attendant to cause trouble through neglect than with the ball bearing type, which from its design, must be totally enclosed to give effective service, and needs a minimum of attention. At one of the large mining companies which has taken a leading part in reducing unit costs and pioneering new developments in mining machinery, ball bearings have been gradually supplanting the conventional type of sleeve bearings on many of their motors, centrifugal pumps, and other machines in the mines. This innovation is not recent, as substitution of ball bearings on mine motors was first tried out by this company in 1909. Since then an increasing number of such bearings have been put in. They are now favored because of increased operating efficiency and reduction in lubrication costs.

Jan 1, 1926

By Carl F. Floe, Michael B. Bever

ACCELERATED by the demands of war, research and development work in nonferrous physical metallurgy has continued at a rapid pace during the past year. In particular, advances have been made in processing and fabrication, especially of the light alloys, and in the surface treatment of metals. Theoretical physical metallurgy, although less active, has not been neglected and the year has brought forth some -notable contributions to our understanding of the fundamental structure of metals and their behavior in service. Of course, much work that has been done cannot be publicly discussed because of wartime restrictions.

Jan 1, 1945

By Robert F. Mehl

PROGRESS in the general field of nonferrous physical metallurgy during the past .year has been uneventful but healthy. A continued increase is apparent in the number of useful alloys and in the mechanical treatment and heat- treatment of finished metals and alloys nothing can hinder the multiplication of alloys or the diversification of their treatment as knowledge of the behavior of .alloys increases; as ternary and quaternary alloys are better understood, hundreds of new metal combinations with unusual properties may well be expected. Evidence of rapid progress is already at hand.

Jan 1, 1936

By AIME AIME

I N JUNE, 1918, at a meeting of the American Society of Mechanical Engineers in Worcester, Mass;, a resolution was adopted for a committee to investigate the aims and organization of that society. This was followed subsequently by similar independent action on the part of the Society of Civil Engineers. The other two Founder Societies were approached and requested to appoint similar committees, the four committees to combine as a .Joint Development Committee, later called the Joint Conference Committee, to investigate what might be done in the way of coordinating those activities of the Founder Societies which ape of common interest, and which were then being pursued separately. The Joint Conference committee worked diligently -for almost. two years and. brought forth a tentative as outlined in its report which was published in full in MINING AND. METALLURGY, December, 1919. It recommended the formation of a nation-wide organization to be composed of representatives' of all of -the engineering societies, local, state, regional, or national, the object to be to further the interest of the public through the use of technical knowledge and engineering experience, and to consider and act upon matters common to the engineering and allied technical professions. Whereas the technical societies have large fields of endeavor in welfare work, and their prime. efforts are 'still in technical lines, this new organization was to be devoted entirely to service, looking to the welfare of the nation and the engineering profession, and to service for the public in local and state affairs.

Jan 1, 1920

By L. Weaver

THE Tennessee Copper Co.'s mines are in the southeast corner of the state of Tennessee. Polk Co., in the well-known Ducktown copper basin. Their new circular production shaft will eventually be the only ore hoisting shaft, and is located for handling ore from Boyd, Calloway, Mary, and Cherokee mines. A circular, rather than a rectangular, shaft was decided upon because: 1-The circular shaft section is stronger when lined with concrete. Reinforcing steel was not required, thus reducing lining cost by one- quarter. 2-Water sealing was desired; it was thought it could best be done with a concrete lining followed by pressure grouting to eliminate water seeps. 3-The shaft labor saving equipment could best be used in a large opening, so the round section was made for economy, sinking, mucking, concreting and water sealing. Less shaft steel is used than could have been possible with steel sets. There are no posts required; center beams and Tee plate assembly placed at 10 ft hold the 100 lb steel guide rails. The shaft is 12 ft 7 1/2 in. ID of the concrete walls. This is large enough for two 10-ton hoisting skips and a ladder compartment. One of the skip compartments is for hauling equipment. The grouting equipment was a 2%xlO-in. Gardner-Denver grout pump, air powered and developing 1000 lb pressure. A grout mixer, also air driven, fed the mixed solution into a tank coupled to the pump suction. Grout materials used were mostly water and Portland cement. Some Bentonite was used to seal porous ground near the surface.

Jan 11, 1950

By Courtenay de Kalb

THE Exposed Treasure gold-mine has, for the past four years, been one of the largest producing mines of Southern California, its annual output having constituted 1 per cent of the total gold and silver production of the entire State. At the present moment the property is idle, owing to the large quantity of water encountered oil the lower levels, which will require the installation of a powerful pumping-plant before operations can be recommenced. Moreover, a prompt change in the character of the ore has occurred at water-level, which makes imperative an extensive campaign of development in the region of the unoxidized ores before a plant adapted to their treatment can be definitely decided upon. The character of the changes encountered in these deeper ores makes the geology of this deposit a matter of importance, not only for the immediate district, but for the desert region of Southern California in general, where many mines exist having in the oxidized belt conditions that, in many respects, resemble those in the Exposed Treasure mine. The deposit is situated in an apparently isolated butte about 2.5 miles south from the town of Mojave, on the Mojave desert; The butte, though apparently isolated, is in fact geologically part of an extinct volcano, known as Soledad butte, which rises out of the plain 1,5 miles SW. of the mine, to an altitude of 4,650 ft. above sea-level. Other buttes also rise from the desert plain toward the south and east, and again to the westward, all being closely related geologically to Soledad butte,-the whole constituting a single system as to origin and time. Since the end of the period of active volcanism in this region, there has been extensive denudation, the ancient plateau having been dissected during an epoch of apparently exces-

Jan 1, 1907

By Robert S. Williams

NO new ferrous alloys have been produced in the last five or six years that are as outstanding contributions to civilization as were the high-speed steels of the early part of the century or the stainless steels announced at the close of the World War. There have been, however, many developments of major importance having to do either with modifications of existing alloys or with new methods of treatment of older iron or steel alloys. Only a limited number of these new developments can be discussed and their selection does not necessarily imply that these are the most important but merely that they are of general interest rather than perhaps of greater importance in highly specialized fields.

Jan 1, 1939

By David A. Thomas, David N. French

The lrnrdness of WC crystals has been measured with the Knoop indenter at loads of 100 and 500 g on the (0001) and (1070) planes. The hardness as tneasitred on the basal plane is 2400 kg per sq mm and shows little anisotropy. The hardness on the prism plane, however, shows a marked orientation dependence, with a low value of 1000 kg -per sq mm when the long axis of the Knoop indenter is oriented parallel to the c axis and a high value of 2400 kg per sq mm when the indenter is perpendicular to the c axis. Slip lines (Ire observed surrounding the microhardness indentations and they show slip on (1010) planes, probably in [0001] and (1120) directions. This slip behavior can be explained by the crystal structure of TVC, which is simple hexagonal with a c/a ralio of 0.976. The hardness anisotropy call be explained by [0001]{1010} and (1130) {10l0] slii) and the resolved shear-stress analysis of Daniels and Dunn. HARDNESS anisotropy is a well-known phenomenon and has been reported for many metals, with both cubic and hexagonal structure.1-6 For hexagonal tungsten carbide, WC, a wide range of hardness values is reported in the literature. For example, Schwarzkopf and Kieffer7 give a hardness of 2400 kg per sq mm and report a value of 2500 kg per sq mm by Hinnüber. Foster and coworkerss give the average Knoop microhardness as 1307 kg per sq mm with a maximum value of 2105 kg per sq mm. Although these values and the structure of WC suggest the likelihood of hardness anisotropy, no such measurements have been made. We first detected a large apparent hardness anisotropy in WC crystals about 75 p large, in over-sintered cemented tungsten carbide. Prominent slip lines also occurred around many indentations. This report presents further observations and interpretations of hardness anisotropy and slip in WC crystals obtained from Kennametal, Inc. Both Knoop and diamond pyramid indenters were used on a Wilson microhardness tester with loads of 100 and 500 g. EXPERIMENTAL RESULTS The carbide crystals tended to be triangular plates parallel to the (0001) basal plane of the hexagonal structure. The side faces were parallel to the ( 1010) prism planes. Specimens were mounted approximately parallel to these two types of faces and metallographically polished. Laue back-reflection X-ray patterns were used to orient the specimens, which werethen ground to within ±1 deg of the (0001) and (1010) planes. The Knoop hardness values measured on the basal plane are plotted in Fig. 1. There is only a small anisotropy, with a hardness range of 2240 to 2510 kg per sq mm. The additional points at angles from 52.5 to 67.5 deg confirm the sharp minimum hardness at 60-deg intervals, consistent with the sixfold hexagonal symmetry. The average hardness of all values obtained on the basal plane is 2400 kg per sq mm. While the basal plane shows only slight anisotropy, the (1010) plane exhibits marked hardness anisotropy, from 1000 to 2400 kg per sq mm. Fig. 2 shows the hardness as a function of the angle between the long axis of the indenter and the hexagonal c axis, the [0001] direction. The minimum and maximum occur when the indenter is oriented parallel and perpendicular to the [0001] direction, respectively. The anisotropy of the prism plane is contrary to that reported for hexagonal zinc and hard- However, the basal-plane anisotropy is similar to these two metals.1'2 To check the accuracy and reproducibility of the measurements, a series of fifteen impressions was made at 100-g load in the same orientation in the same area of the specimen surface. The average for all was 2040 kg per sq mm, with a range of 1950 to 2130 kg per sq mm, giving an accuracy of about ± 5 pct. Thus the slight anisotropy on the basal plane is almost within experimental error. Fig. 3 shows slip lines around the Knoop indentations on the basal plane. The slip traces are in directions of the type (1130). The presence of slip steps on the basal plane indicates that the slip direction lies out of the (0001) plane. Because WC has a c/a ratio of 0.976,' the shortest slip vector is [0001], which suggests slip systems of the type [0001] (1010). Fig. 4 shows slip lines around the Knoop intentations on the (1010) plane. These slip lines are inconsistent with [0001] slip but can be

Jan 1, 1965

By H. K. Work, H. B. Emerick

IN the past year the steel industry underwent an abrupt conversion from a war tempo to a highly competitive peacetime schedule. It is still too early to gain a comprehensive picture as to which of the measures in production metallurgy, that made the war effort so successful, will remain in the postwar production of steel, but many of them undoubtedly will fill an important place after the war. Considerable speculation has developed regarding the disposition of the war-born production facilities of the steel industry. These include new open-hearth and electric furnaces, as well as vast numbers of auxiliary, supplementary, and balancing units that increased and speeded up production beyond the normal capacities of existing melting furnaces and finishing mills. Although these facilities were installed primarily to help meet war requirements, consideration was also given, in planning, to their possible peacetime use. The new equipment is generally modern and efficient, and it seems reasonable to suppose that strategically located units will gradually be absorbed by various steel companies to supplement their own facilities, or to replace in kind, obsolete and inefficient equipment now ready to be scrapped. Some, however,

Jan 1, 1946

By Arthur F. Hagner

The titaniferous magnetite deposit at Iron Mountain, Wyoming, is in Precambrian anorthosite. Individual ore bodies are lenses, commonly arranged en echelon, conformable to the platy crystal structure and compositional layering of the anorthosite; a few transect these features at various angles. The ore bodies are on the east flank of the principal anticline in the anorthosite mass. Magnetite and ilmenite, accompanied by spine!, are the ore minerals. The principal gangue minerals are olivine, which was introduced with the ore, and plagioclase, the chief constituent of the anorthosite. The anticlinal region appears to have been a structurally weak zone, and westward-bowing curves of the axis were especially favorable sites for localization of the two largest massive ore bodies. These bodies are synclinal and plunge southeast. The proportion of magnetite-ilmenite to olivine and to anorthosite appears to be related to structural features. Where magnetite-ilmenite is present with olivine, the magnetite-ilmenite is encountered along the most pronounced parts of a fold where anorthite content is highest, whereas olivine is associated principally with more gently folded portions. During granulation and recrystallization of the anorthosite mass, temperature and pressure changes furnished the energy required to release and mobilize iron and other elements that migrated to areas of low pressure, the ore zone. Some iron and magnesium may have combined with silica from partly dissociated plagioclase to form olivine. The ore formed by replacement of anorthosite as indicated by: (1) the marked changes in mineralogy along strike, dip, and plunge of an ore body; (2) the concentration of massive ore in folds and olivine on limbs; ( 3) the halo of low-grade mineralized rock that transects the structure of the anorthosite in the hanging wall; and ( 4) the layering in the large southern ore body, that strikes more easterly than the trend of the body.

Jan 1, 1968