Search Documents

By Donald W. Scott, Nathaniel Arbiter, A. C. Richardson

THIS paper describes the application of amine flotation to a specific problem-that of increasing the grade of magnetite concentrates derived from an iron ore requiring extremely fine grinding for mineral liberation. Experiments conducted on an iron ore from Wisconsin had shown that concentrates containing 60 to 62 per cent iron and 12 to 14 per cent silica could be produced by magnetic separation. The residual silica occurred as quartz and hornblende, either entrained or locked with magnetite. Most advantageous utilization of the concentrate, however, necessitated that the silica content be reduced to about 5 per cent, equivalent to an iron content of 67.5 per cent. It had been demonstrated that tabling of the magnetic concentrate removed sufficient quartz and hornblende to yield an acceptable concentrate, but disadvantages inherent in tabling dictated that flotation be investigated as a substitute. The goals set for the flotation investigation were: (I) the production of concentrates of about 68 per cent iron content from the magnetic concentrate; (2) an iron recovery of about 85 per cent of that in the feed to flotation; and (3) minimum reagent cost. Both batch and continuous flotation tests were employed; the former, to establish the procedure and the latter to verify it. Although the data were obtained on a specific ore, and with a commercial application in view, it is believed that they have a bearing on other problems where amine flotation is being used or is anticipated. SAMPLES Two samples, designated "minus 100mesh magnetic concentrate" and "minus 150-mesh magnetic concentrate," were used for the batch experimental work. They differed only in the degree to which the crude ore was ground prior to magnetic separation. They were stored moist in steel drums in quantities sufficient for all the experimental work reported. This procedure had the advantage of allowing all tests to be made on common samples, but had the disadvantage that the individual flotation samples, because of the difference in storage time, were subject to various stages of surface alteration. Previous work had indicated that common samples were desirable for the batch studies, and it was decided that if these data appeared sufficiently promising the effect of surface alteration could be checked best by continuous tests. The size distributions and the assays of the samples are given in Table I. The minus 150-mesh magnetic concentrate, on which most of the flotation tests were made, assayed 60.9 per cent iron, 13.3 per cent silica, and 0.016 per cent phosphorus. The minus 325-mesh portion represented 78.1 per cent of the sample by weight, and assayed 67.9 per cent iron. Thus, the insoluble, mainly silica, was concentrated

Jan 1, 1945

By H. W. Fox, M. R. Achter

IN a previous study of the effect of atmosphere on creep-rupture properties,' it was shown that the relative strength of nickel in air and in vacuum may be reversed by a change in either stress or temperature, Fig. 1. At low stresses and high temperatures the metal is stronger in air but stronger in vacuum at high stresses and low temperatures. A mechanism to explain this reversal was proposed involving two competing processes; oxidation strengthens the metal while adsorption of gas lowers the surface energy, relative to that in vacuum, and reduces the work required to propagate a crack. The process which controls is determined by stress and temperature. In a number of private communications, however, the objection has been made that even in the vacuum of objection mm of Hg used in this study, the surface of a

Jan 1, 1960

By E. Gybbon Spilsbury

The recovery of gold and silver from their ores by means of the cyanide process has been so successful in the last few years that ally radical improvement would seem impossible; yet the appliance to which I wish to call attention in this paper is really a radical departure from the methods now in general use. The most modern and approved of these, known as the all-slimillg method, depends for its success on the grinding of the ore so fine that practically 90 per cent. of it will pass through a 200-mesh screen. The slimes thus produced are then agitated and aerated in tanks of various types. The main object of this treatment is to insure such a thor-

Jan 1, 1911

By C. W. Merrill

The price records of seven representative mineral commodities for the 68-year period 1890 through 1957 have been compiled and analyzed for significant trends. When these records are reduced to real prices in terms of dollars of constant purchasing power or to the purchasing power of industrial wages at average rates, a substantial overall fall in prices is revealed. This downtrend contradicts the widely held concept that heavy drafts on a mineral resource must lead to scarcity, reflected in rising prices. Three metals (aluminum, copper, and pig iron), two fuels (bituminous coal and petroleum), and two nonmetals (sulfur and cement) have been chosen because of their pre-eminence in their respective categories, their significance in an industrial economy, and the ready availability of their price records. It might be added that these seven commodities were selected before any price figures were compiled; none was selected or rejected to substantiate any preconceived notions as to price trends. The overall importance of the seven is demonstrated by the fact that, taken together, they composed over three-fourths of the value of all minerals produced in the U. S. in 1957. The first step in the analysis was to reduce the price records to a basis for significant comparisons. Two such comparisons have been made: 1) The quantities of each of the commodities that could have been purchased for an average hour's wage in each year, and 2) the unit price of each commodity through the years in terms of deflated dollars. These data are set forth in the accompanying table and two charts. The quantities of the mineral commodity purchasable with the average wage for one hour's work in all manufacturing industries through 1926 were based on annual average prices and on average annual wage rates determined by Paul H. Douglas and published in his "Real Wages in the United States, 1890-1926." The series was extended through 1957 by the Bureau of Labor Statistics, U. S. Department of Labor. Calculations based on these data show that the average worker could have purchased 1.28 lb of copper with his hourly wage in 1890, whereas his hourly wage would have purchased 8.11 lb in 1957, an increase of 633 pct in the 68-year period. An average hour's wage would have bought 10.85 gal of petroleum in 1890, compared with 33.04 gal in 1957. Even more spectacular is the increase in sulfur, of which 25.25 lb could have been purchased with the 1904 average hourly wage; 223.08 lb were purchasable with the wage in 1957—an increase of 883 pct. Comparable price data for sulfur are not available for years earlier than 1904. For every commodity, the calculations show an improvement in the wage earner's purchasing power in 1957 compared with the early years. Measuring purchasing power in terms of wages does not give an entirely fair picture of the availability of a commodity in an economy. When the efficiency of an economy changes and the balance shifts among such elements as raw-material production, manufacturing, and service trade, the economic significance of an hour's work changes. Partly to meet such criticism, but mostly to present another interesting measure of the response of minerals to changing market conditions, a second set of calculations has been made to deflate unit prices for the seven commodities into terms of 1954 dollars. To accomplish this adjustment to a common 1954 parity, the Gross National Product Price Deflator, developed by the Office of Business Economics, U. S. Department of Commerce, was used. Although the results of these calculations are not as striking as those based on labor's increasing purchasing power, nevertheless the declines outweigh the rises in the prices of the mineral commodities. In terms of these deflated prices, aluminum and sulfur are much cheaper today than in the early years; copper was substantially cheaper in 1957 than in 1890; pig iron and petroleum are little changed; and only bituminous coal and cement have increased substantially. Strangely, the two mineral commodities with the strongest reserve positions are the two to exhibit rising real prices. Now this apparent overall downtrend in prices has taken place during a period of almost fantastic increase in the demand for mineral products. The value of minerals consumed in the world during the period greatly exceeds all mineral consumption up to 1890. A stage has been reached in the U.S. in which 95 pct of the energy used is of mineral origin and in which machines, structures, roadways, communication facilities, and most other elements in the industrial economy are primarily of mineral origin. Even agricultural fertility is maintained, in large measure, by mineral fertilizers. A series published in Minerals Yearbook shows that the value of U. S. mineral products has risen from $615 million in 1890 to $18,000 million in 1957, a 29-fold increase. Even in deflated dollars, the increase has been eightfold, while population has expanded less than threefold. Not only are demands of the industrial nations— the U. S., countries of Western Europe, and Japan— increasing at rapid rates, but those countries with agrarian economies are calling themselves underdeveloped and clamoring to industrialize. The ever-expanding mineral requirements in the U. S. and throughout the world show no abatement. Mineral reserves frequently have been described as wasting assets. Much concern has been shown for future users, who have been pictured as finding themselves on a plundered planet. Conservationists have viewed the future with alarm and have demanded legislation and regulations to reduce the drain on mineral reserves.

Jan 1, 1960

By C. H. North, L. E. Lynd, W. W. Anderson, H. Sigurdson

CONSIDERABLE uncertainty is revealed in the literature regarding the nature of the titanium minerals which make up the bulk of the heavy, opaque fractions of numerous beach sand deposits of the world. An investigation was made, therefore, of beach sand concentrates of North Carolina, Florida, Brazil, and India. Magnetic concentration, X-ray, and microscope data were obtained which show that these concentrates consist essentially of ilmenite and its alteration products. The alteration, brought about by oxidation and leaching of iron values, has resulted in upgrading the ores to a range of 56 to 64 pct TiO2, as compared with 52.7 pct in ilmenite of theoretical composition. Conclusions drawn regarding the nature of the dominant titanium-bearing mineral in beach sand deposits have been based mainly on chemical composition, specific gravity, and petrography. This material has usually been referred to as ilmenite or weathered ilmenite. It has also been referred to as arizonite because in chemical composition it resembles an occurrence in Arizona which was described by Palmer1 in 1909.

Jan 8, 1954

Jan 1, 1879

By Evangelo Agelopas

Steelmaking operators are familiar with the costs involved when ingot molds must be scrapped prematurely because of the failure of a stripping or turning lug. Some mold sizes can be expected to produce one hundred or more ingots per mold before normal wear causes the mold to become unserviceable. Therefore, the failure of lugs at less than the average life for that mold size represents a sharp increase in terms of mold cost per ingot ton produced. To combat these wasteful and costly occurrences, it was determined that an efficient method of replacing lugs should be developed to extend the life of molds which are otherwise in good condition. The purpose of this paper is to describe a lug welding method which has proved effective and economical. This method is known as the Oxygen and Mapp Process.

Jan 1, 1972

By C. H. Li, R. J. Stokes, T. L. Johnston

A portion of the Ni3Cr-Ni3Al phase dzagram has been investigated, including the precipitation of 1 (Ni3Al) as well as the existence of ordered Y (Ni matrix), Extensive metallographic studies by electron microscopy have been carried out and X-ray diffraction diagrams have been taken at both elevated and ambient temperatures, No long-range ordering of the phase was found above 893°C (1639°F) in the compositional range investigated. The high rate of formation of the ordered ?1 phase upon quenching has been confirmed, a phenomenon which up to the present Lime has retarded the understanding of this phase diagram, Specimens with controlled amounts of ?1 exhibited up to a six-fold improvement in yield and creep strength compared with single-phase Ni-Cv-A1 alloys. MOST of the important high nickel heat-resistant alloys are related to the nickel-chromium-aluminum system. One of the important functions of the aluminum, often accompanied by titanium, is to produce a precipitate of the very fine ?1 phase (Ni3A1, X) where X may be Ti, Cr, or other elements. A number of investigators1-" have demonstrate the presence of y' in these alloys but most of their materials contained large amounts of other elements resulting in appreciable amounts of con- fusing phases such as carbides. Further clouding of the precise role of y' has been the suspected existence of an ordering reaction in the y matrix itself, ro-3,12-17 It appeared from these investigations that aluminum in Ni-Cr alloys would raise the ordering temperature of the matrix from 540°C at NisCr to 1300°C at Ni,Al. In support of this possibility, the matrix phase in the parallel Ni-Fe-A1 system is ordered to very high temperatures.1 OBJECTIVES OF THIS RESEARCH From this survey of the literature it appeared desirable to conduct an investigation of the simple Ni-Cr-A1 system using the alloys of the highest available purity to avoid the complication of foreign phases and thereby isolate the structures in the Ni-Cr-A1 system. Procedures were developed to study ? - ?o and ? - ?1 equilibria. Preliminary mechanical tests at elevated temperatures were also conducted.

Jan 1, 1962

By H. I. Smith

CONTENTS [PAGE Problems of Mining and Processing Mineral Aggregates (TP 1649, by NATHAN C. ROCKWOOD, Min. Tech., Nov. 1943. Discussion by H. I. SMITH, IRVING WARNER and the author) t Mica in War (TP 1749, by RUSSELL G. WAYLAND, Min. Tech., July 1944. Discussion by H. S. SPENCE) 3 Three Roofing-granule Plants in Pennsylvania (TP 1787, by RICHARD M. FOOSE, Min. Tech., Jan. 1945. Discussion by H. I. SMITH)5 Methods of Prospecting and Mining Optical Calcite in Montana (TP 1896, by E. W. NEWMAN, Min. Tech., Nov. 1945. Discussion by W. C. STOLL and FRANK C. ARMSTRONG, and the Glass Sand and a Glass Industry in Puerto Rico (TP 1939, by HOWARD A. MEYERHOFF and J. EARL FRAZIER, Min. Tech., Nov. 1945. Discussion by A. M. SHORT, the author and PHILIP The "Bonanza" Mica Operation of Purdy Mica Mines, Limited, Mattawsn Township, Ontario (TP 2154, by HUGH S. SPENCE, Min. Tech., March 1947. Author's supplement and discussion by JOHN A. BAKER, E. J. LINTNER, and the author) 7 Process for Manufacture of Dead-burned Magnesite and Precipitated Calcium Carbonate from Dolomite (TP 2155, by ROBERT D. PIKE, Min. Tech., March 1947. Discussion by 0. C. RALSTON and the author) 9] Problems of Mining and Processing Mineral Aggregates H. I. SMITH*-Mr. Rockwood has presented a very interesting paper on problems of the mineral aggregate industry in meeting specification requirements, which apparently are ever decreasing in tolerance. May I call attention to a method of mineral separation that may be of value in separating the flat aggregate particles from the more angular ones and possibly the soft particles from the hard. The method is the old Pardee spiral coal separator, extensively used many years ago in the anthracite region for separating rock and bone from anthracite coal.1 The success of the process depends on the relative coefficient of friction of the aggregate particles to be separated rather than on their relative specific gravity. The flat and the soft particles normally will slide more slowly and stay on the inner spiral until they reach the delivery spout at the bottom whereas the round and the angular pieces will work to the outer edge and fall off into a spiral of larger diameter. The capacity of the separator is increased materially by having three inner spirals, with a separate feed for each, on which the particles travel more slowly, and one outer spiral from which the more rapidly traveling pieces slide to the bottom. IRVING WARNER*-I have long been convinced that much of the equipment and methods developed for mineral dressing might be advantageously employed in the mineral aggregates industry, and more particularly in the production of sand and gravel. The two industries are not well acquainted with each other or their problems. They have separate trade publications. The difficulty with the situation is that there are few large sand and gravel plants and few provided with technical services in their own organization or by retainer. This does not refer to engineering organizations but rather to improvement of plant technic in processing.

Jan 1, 1947

By C. D. Rugen

Ground raw material as fed to the cement kiln generally is a mixture of two to four components, each of which may have widely varying physical and grinda-bility characteristics. Chemically similar materials found in the same or different deposits may also differ appreciably in physical properties, depending on their crystalline structure. The calcareous or principal cement raw material may vary from a soft chalky limestone or friable cement rock at one plant to a hard limestone or oyster shell at another plant. Argillaceous materials include clays, shales and granulated slag. Siliceous and/or iron-bearing material, including sand, 'iron ore and cinders, may also be required in addition for certain types of mixes. Frequently differences in grindability characteristics are not given the attention they deserve in comparing grinding results at one plant with those at another or in selecting suitable circuits or equipment. Many types of crushing and grinding units are used, with numerous open and closed circuit arrangements. Both wet and dry processes are used successfully. When rebuilding or installing a new grinding department, the choice of process or circuit in some cases may be dictated by the nature of the materials being ground but in other cases it may be the result of good salesmanship or a compromise. An over-all evaluation of wet process vs. dry process grinding should not be made without considering the effects on all other *producing departments in the plant. In general, the more recent grinding installations, both wet and dry, have employed closed circuits, but many older open circuits are still in successful operation. In our experience, closed-circuit raw grinding pays, because of lower power consumption and less operating labor per ton of product. However, some dry open-circuit mills with improved equipment and operating methods compare favorably in performance with dry closed-circuit units. Character of Ground Raw Mix (Kiln Feed) Grinding in the cement plant in general requires a considerably finer product than in most ore-grinding operations. A distinction between fineness of kiln feed and of cement may be made in that kiln feed preferably should be ground to a limiting size,whereas finished cement should include a range of size fractions including sufficient fine flours to give a product with satisfactory physical qualities. Grinding raw mix for kiln feed therefore is more comparable to ore grinding, although the limiting size is smaller. Most kiln feeds are ground from 85 to 95 per cent passing 200-mesh, depending on mix composition. Some cement chemists believe that raw materials cannot be too fine, since her particles theoretically combine more readily and intimately in the kiln. However, there are certain definite practical objections to extremely he kiln feed, such as loss of kiln dust, unstable material flow through the kiln and greater difficulty in control of chemical composition due to dust loss, and the disproportion of fines from the more easily ground component. Our

Jan 1, 1948

By C. D. Rugen

Ground raw material as fed to the cement kiln generally is a mixture of two to four components, each of which may have widely varying physical and grinda-bility characteristics. Chemically similar materials found in the same or different deposits may also differ appreciably in physical properties, depending on their crystalline structure. The calcareous or principal cement raw material may vary from a soft chalky limestone or friable cement rock at one plant to a hard limestone or oyster shell at another plant. Argillaceous materials include clays, shales and granulated slag. Siliceous and/or iron-bearing material, including sand, 'iron ore and cinders, may also be required in addition for certain types of mixes. Frequently differences in grindability characteristics are not given the attention they deserve in comparing grinding results at one plant with those at another or in selecting suitable circuits or equipment. Many types of crushing and grinding units are used, with numerous open and closed circuit arrangements. Both wet and dry processes are used successfully. When rebuilding or installing a new grinding department, the choice of process or circuit in some cases may be dictated by the nature of the materials being ground but in other cases it may be the result of good salesmanship or a compromise. An over-all evaluation of wet process vs. dry process grinding should not be made without considering the effects on all other *producing departments in the plant. In general, the more recent grinding installations, both wet and dry, have employed closed circuits, but many older open circuits are still in successful operation. In our experience, closed-circuit raw grinding pays, because of lower power consumption and less operating labor per ton of product. However, some dry open-circuit mills with improved equipment and operating methods compare favorably in performance with dry closed-circuit units. Character of Ground Raw Mix (Kiln Feed) Grinding in the cement plant in general requires a considerably finer product than in most ore-grinding operations. A distinction between fineness of kiln feed and of cement may be made in that kiln feed preferably should be ground to a limiting size,whereas finished cement should include a range of size fractions including sufficient fine flours to give a product with satisfactory physical qualities. Grinding raw mix for kiln feed therefore is more comparable to ore grinding, although the limiting size is smaller. Most kiln feeds are ground from 85 to 95 per cent passing 200-mesh, depending on mix composition. Some cement chemists believe that raw materials cannot be too fine, since her particles theoretically combine more readily and intimately in the kiln. However, there are certain definite practical objections to extremely he kiln feed, such as loss of kiln dust, unstable material flow through the kiln and greater difficulty in control of chemical composition due to dust loss, and the disproportion of fines from the more easily ground component. Our

Jan 1, 1948

By A. Thies, Wm. B. Phillips

1. Introductory Remarks.—The Haile Gold Mine is in Lancaster county, South Carolina, 3 1/2 miles east of Kershaw station on the Charleston, Cincinnati and Chicago Railway. It was first opened about, the year 1832, and since that time has passed through various fortunes. Many different operations have been practiced here for extracting the gold : panning, grinding in Chilian mills or arrastras, stamping, the Designolle process, dry-crushing, and finally the Thies process of barrel-chlorination, which has now been in successful use for 2 1/2 years, and by which 36,000 tons of ore have been treated profitably. The Thies process is in brief the treatment of dead-roasted auriferous concentrates (pyrite, sometimes also chalcopyrite, as at the Phœnix mine, Cabarrus Co., N. C.) with nascent chlorine, without ' artificial pressure or exhaust, in lead-lined iron cylinders; the throw-

Jan 1, 1891

By C. W. Clark

Two papers have been written previously concerning operations at the Montreal East plant of Canadian Copper Refiners Limited. The first one,1 written in 1932, described silver-refinery operations at the time for producing silver and gold bullion from tankhouse anode slimes; the second,2 published in 1933, consisted of a description of the entire plant. Since publication of these papers the refinery has become the world's larg-est producer of refined selenium. The first selenium was produced in August 1934. Tellurium production on a. commercial scale followed in October 1935. This paper will deal with selenium and tellurium produc-tion and also with present operations in the silver refinery. Blister cakes from Hudson' Bay Mining and Smelting Co., Flin Flon, Manitoba, and commercial anodes from Noranda Mines Limited, Noranda, Quebec, are refined at Montreal East. Both these bullions have unusually high gold, selenium and tellurium content. The average assay of raw slimes produced from domestic and Noranda anodes is about 40 per cent Cu, 3600 oz. per ton Ag, 800 oz. per ton Au, 22 per cent Se and 3.7 per cent Te.

Jan 1, 1938

By George Kenzy, Charles B. Manula

This paper introduces a philosophy of dynamic modeling. Here, the development of a simulation model of a coal mining system is described for the purposes of: (a) system design and selection of equipment for a new operation; (b) analysis of existing operation' for possible alterations, additions, or general improvements.

Jan 1, 1976

By Archer Wheeler

THE copper industry in the Province of Katanga, in the Belgian Congo, which is now controlled and operated by the Union Minere du Haut Katanga, had its inception many years ago in the vision of a Scotsman, Robert Williams, now Sir Robert Williams, Baronet. He it was who personally negotiated the mineral concession with King Leopold of Belgium, sent in the prospecting parties who located most of the present mines of the company, later arranged for the Belgian participation from which the present company was formed, and has been its active mentor ever since. The idea back of his efforts was the establishment of an industry on the Congo-Zambezi divide, of sufficient importance to draw up to it the head of the Cape to Cairo Railroad, the dream of Sir Cecil Rhodes, and the consummation of which he had left as a legacy to Mr. Williams, his successor. The reports of the prospecting expeditions showed that copper in profitable quantity was there, but many difficulties lay in the way of the establishment of the infant industry. The isolated location of the mines, various tribal wars, the Boer War, and many other factors contributed to making progress very slow. However, in spite of these difficulties the railroad was finally built and a blast-furnace plant erected at Lubumbashi, near Elisabethville, the capital of the Province. Operations of this plant were started in 1911, treating high-grade oxidized ores and producing pig copper by a reducing smelting. Production has been continuous since that time and the company has grown so that at present it ranks as the largest individual copper producer in the industry. It is a fitting monument to the foresight, optimism and driving force of its founder, and the progressive policies of his Belgian colleagues. In January, 1914, the Union Miniere du Haut Katanga engaged as its consulting engineer, Archer E. Wheeler, metallurgical engineer, at that time general superintendent of the Great Falls plant of the Anaconda Copper Mining Co. Mr. Wheeler was commissioned by the Board of Directors to proceed into Katanga, and make all necessary investigations to enable him to report on a comprehensive development program, and to recommend a scheme of treatment particularly for their low grade

Jan 1, 1932

Discussion of the paper of HOWARD N. EAVENSON, presented at the New York meeting, February, 1915, and printed in Bulletin No. 98, February, 1915, pp. 413 to 430. WILLIAM H. GRADY, Bluefield, W. Va.-Mr. Eavenson gave a comparison between accidents in the State of West Virginia and in the Pocahontas field. The figures quoted are, I presume, taken from the reports of the State Mine Inspector. There are no statistics available, in readily accessible form, giving a comparison between the Pocahontas field and the mines of the United States Coal & Coke Co. which are a part of the field. It occurs to me that the paper would be more complete with these data and I will say that the mines of the Pocahontas field produced during the year 1913 about 15,000,000 tons, about 3,000,000 tons of which was produced by the United States Coal &Coke Co. This gives an indication of the extent of its operations. The Pocahontas field lies largely in the counties of McDowell, Mercer, and Wyoming in West Virginia, and Tazewell in Virginia.: Without consulting maps, I should say that all of the acreage under operation at present by this company lies wholly in McDowell County and that the average conditions off roof top and bottom in its mines are the average of the county, but that the worst conditions in some of these mines are the worst to be found in the county. The average conditions in Tazewell County are about the same as in McDowell County, except that the average thickness of the seam is much greater. The average conditions of top and roof and bottom are better in Mercer and Wyoming counties than in the mines of the United States Coal &. Coke Co.; the worst conditions in these counties are not so bad as in McDowell and Tazewell counties and the best are better than those encountered in McDowell and Tazewell counties; also the thickness of seam is less in Mercer and Wyoming counties. THOMAS W. DAWSON, Scottdale, Pa. (communication to the Secretary*).-The H. C. Frick Coke Co., the mines of which are in Fayette and Westmoreland counties, Pennsylvania, in the Connellsville coke region, has been pursuing a safety campaign for a number of years and a short resume .of its practices will be of interest in connection with Mr. Eavenson's paper.

Jan 5, 1915

By K. H. Adams, T. Vreeland

The basal stress-strain behavior, dislocation density, and strain vale sensitivity of the flow stress uqere measured at room temperature on single crystals oj-zone-refined zinc , 99.999 pct Zn, and zinc containing 0.0025 and 0.02 wt pct Al. No significant change in the stvain rate sensitivity of the flow stress occurs with the addition of aluminum. Changes in dislocation substructure and nonbasal dislocation density were obserrled with the addition of aluminum. The effect of aluminum on the basal slress-strain behavior is explained in terms of changes in nonbasal dislocation density which determines the separation distance of junctions between basal and nonbasal dislocations. The onset of basal slip is associated with the breaking of attractive junctions. The chunge in basal dislocation density was found to be proportional to the one-third power of the plastic shear strain, indepedent of purity. THE effect of impurities in solid solution on the stress-strain behavior of single crystals has been the subject of many theoretical studies. These studies have generally concentrated on the interactions between impurities and dislocations to explain the hardening effeet of impurity additions. The theories that have been proposed include those of yott and Nabarro,&apos;l&apos; Cott-re11; Suzuki; and Fisher. In practice, it is generally difficult to predict the relative importance of the vari- ous effects due to impurities. In addition, secondary effects of impurity additions such as induced changes in dislocation density and substructure in the as-grown crystals have received little attention. Many experimental investigations have been conducted on the effect of impurities on the stress-strain behavior of fcc crystals. Hcp crystals have not received much attention except for the extensive work of Levine et a1.= on magnesium alloy crystals. Stuwe~&apos;&apos; has studied the effect of copper impurity on the critical shear stress of zinc crystals and has interpreted the results in terms of the impurity atmosphere model of Cottrell and Jaswon. This report presents the results of an experimental study of the effect of aluminum additions to zinc on the basal stress-strain curve and the strain rate sensitivity of the flow stress. Etch pit techniques were used to measure and characterize the dislocation density and substructure in the zinc alloy crystals. EXPERIMENTAL PROCEDURE Specimen Preparation. Compression test specimens of four different purities of zinc were prepared from CP grade zinc of 99.999 pct purity obtained from the New Jersey Zinc Co. An analysis of this material furnished by the supplier indicated the following impurities in wt ~ct: Pb = 0.0002; Fe = 0.0002; Cd = 0.00005; other <0.60011. A quantity of material of this grade was further purified by zone refining. Zone refining was carried out under a helium atmosphere by passing a double &apos;One furnace Over a 6-ft-10ng charge at the rate of 2 in. Per hr. * total of ten double zone passes were made before the charge was removed from the furnace. The first one third of each charge was used to grow single crystals. Quantities of two

Jan 1, 1969

By John J. Curzon

The existence of mineralized ground in the area near Lake Chelan has been known since 1887, when Major A. B. Rogers, a locating engineer for the Great Northern Railway, came up Lake Chelan to Railroad Creek in search of a pass over the Cascade Mountains. The steep mountainsides near the crest of the Cascades proved too difficult for railroad construction, and the project was abandoned. Upon his return to Seattle, Major Rogers apparently told his friends, the Denny family, about the large, red, oxidized patches he had seen on the valley walls along Railroad Creek. The Dennys, being true pioneers in spirit, grubstaked J. H. Holden to explore the area and to stake any promising mining ground, and thus began the chain of events that culminated in the construction of the plant that is now known as the Chelan Division of the Howe Sound Company. Holden staked the first group of claims in 1892. Soon afterward, A. H. Murdock, who was then a storekeeper in Chelan, and who is still living at Waterville, and his partner, W. P. Robinson, staked adjacent ground. These two groups of claims formed a substantial part of the mining property being worked today. During the period from the original staking in 1892 up to 1928, when the Britannia Mining and Smelting Co. optioned the property, many attempts were made to bring the property into production, through the formation of several stock companies and by examination and testing by engineers from several well-known mining companies. Although the Britannia organization optioned the property in 1928, not much was done until 1930, when a subsidiary was formed—the Chelan Copper Mining Co.—to explore further the possibilities of the ground. Some work was done during the next few years, but it was not until March 1937 that the Chelan Division of the Howe Sound Co. took over with a program of "full speed ahead," and active development of the mine and construction of the complete plant was begun, including docks, tug and barges, 54 miles of power line, 11 miles of road, mill, shop buildings and complete camp. Production began in April 1938, and has continued without interruption, except for regular change days and holidays and a six-weeks strike in 1939. This interval of time has seen the gradual evolution of a mine and mill originally planned for a rate of 1000 tons per day into a compact operation that last year averaged 2264 tons per operating day. This operation, although rather small when compared with the large copper producers of the Southwest, is important to the state of Washington for several reasons: It has provided employment for several hundred people continuously since construction days in 1937; it has helped materially in the war effort, through production of vital copper and zinc, without which no war can be won; and last, but not least, it has conclusively refuted the old pessimistic arguments that a successful mine would never be found in the Cascade Mountains of Washington. The Holden mine has been producing

Jan 1, 1946

By J. S. Fulton

THOSE who live in steel-mill towns are so accustomed to the sight of flames spouting from the mouth of a Bessemer vessel that they seldom pause to think of the amazing process behind it. Actually cold air is being blown through a hot liquid and, instead of cooling it, raises the temperature of the liquid. When coffee is too hot to drink, we know that blowing on it will cool it, so it was no wonder that when Henry Bessemer (or William Kelly, as your patriotism chooses) first proposed this cycle of steel production, he was considered mad. When Bessemer and Kelly started their investigations around 1852, there was not much practical knowledge of metallurgy and, in consequence, there was wide variation in the product made by their process. It was appreciated that the silicon, carbon and iron were all potential fuels, but not until Mushet discovered the beneficial effects of having manganese in the pig iron did the process really become commercial. Bessemer&apos;s patent of 1855 covered a crucibleful of liquid iron into which a refractory tuyere was lowered and the blow started. Since that time virtually every conceivable form of vessel, bottom arrangement, tuyere size and location have been suggested or tried. There have been stationary vessels with fixed bottoms, that were side, top or bottom blown; tilting vessels with two sets of side tuyeres at different elevations; vessels like a three-compartment septic tank; vessels of a cylindrical form supported on the long axis with tuyeres along the side submerged by a partial rotation of the vessel (this type continues in copper refineries) ; portable vessels to make the blow in a ladle over a mold in a foundry; a combination of a cupola and converter in one shell, and various other arrangements. But in all these experiments, compressed air for the blast was presupposed and there was little discussion of the quantity or quality of the air delivered to the tuyeres. At one time or another various practices that now are forgotten have been tried or suggested: for instance, the use of inert gas at the end of the blow; the addition of fuel to the blast; the use of hot-blast stoves; the drying of the air to a minimum moisture in the blast. Except in the last-named method little attention was paid to the quality or quantity of the air blown. PHASES Of the many papers published on various phases of the Bessemer process, nearly 170 according to one bibliography, over go per cent were concerned with the metallurgical phase and less than 10 per cent discussed various sections of the pneumatic phase. Since the two phases are coincidental, apparently nine times as much thought has been given to the result as has been given to one of the causes of the Bessemer process. Is it not possible that if more attention had been paid to the pneumatics so many papers would not have had to be written on the troubles in the metallurgical phase? A study of published papers and conversation

Jan 1, 1941

By F. J. Dunkerlery, V. Damiano, J. Fulton, F. Pledger

Grain-growth and recrystallization characteristics of a commercially pure zirconium prepared by the iodide process are reported. Grain growth from 640° to 800°C was continuous once initiated and obeyed D = kt". Recrystallization of zirconium occurred at temperatures of 450° to 550°C after deformations of 20 and 50 pct. Hardening from partially soluble inclusions prevented determination of the absolute rates of recrystallization, but the relative rates of recrystallization obtained are useful as a guide in fabrication practice. BASIC information needed as a guide in the hot and cold working and annealing of metals includes recrystallization and grain-growth data. A search of the literature revealed no such information for pure zirconium. This is a report of practical grain-growth and recrystallization results obtained for a commercial grade of pure zirconium on a project sponsored by the Office of Naval Research. In this work, isothermal grain-growth curves were obtained at five temperatures from 640" to 800°C inclusively; while recrystallization curves have been determined at 450°, 500°, and 550°C for the metal at the deformation levels of 20 and 50 pct. In addition to the usual variables of temperature, time, and deformation, distribution of the second phase found in all commercial grades of iodide zirconium is also treated as an important factor in these grain-growth and recrystallization studies. In conducting this work, two properties of zirconium were particularly pertinent in dictating experimental conditions. First, since zirconium undergoes a transformation from the a close-packed hexagonal form to the ß body-centered cubic form at 862°C, no recrystallization or grain-growth studies were made above 800°C. Second, because dissolved gases (oxygen, nitrogen and/or hydrogen) increase the hardness and lower the ductility of the solid metal, all annealing treatments in this investigation were carried out in vacuum or in a helium atmosphere. Materials and Methods The zirconium used in this investigation was prepared by the Foote Mineral Co. by deposition from its iodide. A spectrochemical analysis of the metal showed the following composition in weight pct: Hf, 2.1; Mg, 0.012; Fe, 0.035; Si, 0.095; Ti, 0.023; Al, 0.037; Mo, trace; Ni, trace; Cr, trace; Ca, 0.006. Conventional metallographic procedures involving hand polishing on wet metallographic papers, followed by final polishing on fine, levigated alumina on gamal cloth and a medium speed wheel were used throughout this investigation. Grain boundaries were revealed with modified Tucker&apos;s etch containing 20 parts glycerine, 2 parts hydrofluoric acid, and one part nitric acid. Grain-Growth Procedure: Three lots of zirconium, designated here as series A, B, and C were prepared for the grain-growth studies as follows: Series A was prepared by cold swaging the % in. as-deposited rod to a 3/16 in. final diameter, followed

Jan 1, 1952