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By W. M. Peirce

The present work has been done in an endeavor to correlate and complete the data on the constitution of alloys of zinc with other common metals, dealing exclusively, however, with the zinc-rich alloys in which the zinc content is between 90 and 100 per cent. This investigation has included the systems lead-zinc, cadmium-zinc, iron-zinc, copper-zinc, aluminum-zinc, nickel-zinc, manganese-zinc, cobalt-zinc, tin-zinc, and magnesium-zinc. The important ternary system zinc-lead-cadmium and the zinc corners of other ternary systems have been investigated in connection with this work but will not be dealt with here. Zinc does not form a single homogenous zinc-rich solid solution over any considerable range of concentration with any of the metals mentioned. A limited range of solid solubility is said, by previous investigators, to occur in several cases and certain effects on the properties of zinc are attributed (with varying degrees of consistency among different writers) to the presence of certain other metals dissolved in zinc. The increasing use of rolled zinc and the possibilities offered by zinc as a casting alloy in certain fields have made it essential to determine precisely these equilibrium relationships. In carrying out this investigation reliance was placed chiefly on two methods, conductivity measurements and microscopic analysis. The first method proved valuable in determining the existence and extent of solid solubility. The second method stands alone as a means of determining structural characteristics and supplements the first method in the measurement of solid solubility. The scleroscopic hardness of all conductivity specimens was measured partly for its value from the point of view of mechanical properties and partly as a check on the conductivity curves in indicating the limits of solid solubility. No hardness curves are included in this paper, for in no case were they important in arriving at the constitution of any system. Conductivity measurements were in all cases made on cold-rolled strips 0.020 in. thick and 0.5 in. wide, both as cold rolled and after an

Jan 1, 1923

There were present eleven Directors, the Institute's Legal Counsel, the Secretary, the Assistant Secretary, and twenty-three guests. The Report of the Committee on Nominations (listed elsewhere) was presented and ordered to take the statutory course. The appointment of a Committee on Mine Taxation was approved. An Advertising Manager was appointed. E. G. Spilsbury and A. S. Dwight were appointed as representatives of this Institute on the Franco-American Engineering Committee. The Transactions were presented to the University of Louvain, and the monthly Bulletin to the French Technical Index. Permission was given to publish in full the argument of William H. Shockley on simplified spelling. A committee was appointed to have charge of the publication of the Raymond Memorial Volume. There were elected 70 members, 15 associates, and 1 junior associate. Three members were reinstated and the resignations of two were ac-cepted. The clues of 10 members who had been in active service with the allied armies were remitted. An extension of time for the payment of dues was granted to the 11 members.

Jan 12, 1919

By Kenneth A. Gutschick, Robert S. Boynton

Lime has become a general and loosely used term to denote almost any kind of calcareous material or finely divided form of limestone or dolomite, as well as burned forms of lime. However, according to Webster, lime is only calcined limestone (known as quicklime, unslaked lime, or calcium oxide). It also embraces the secondary product of quicklime, i.e., hydrated lime or slaked lime (calcium hydroxide). There are two basic types of limestone used for lime manufacture-high calcium and high magnesium (dolomitic). The dolomitic quicklimes and hydrated limes correspond to their "high calcium" counterparts. The only difference is that the dolomitic types are a combination of the elements calcium and magnesium, in varying percents, whereas high calicum limes contain less than 5% MgO down to 1/2%. In either case a pure form of limestone of at least 97% combined carbonate content is needed to make salable lime, barring a few exceptions. The calcination of both types is diagrammed chemically as follows: [ ] In the foregoing reversible reactions the limestone is burned (calcined) in lime kilns, with the carbon dioxide content of the stone expelled as a gas. The weight loss during calcination of pure high calcium limestone is 44%; with equimolecular dolomitic limestone, the weight loss is 48%. Since lime has a strong affinity for CO_, particularly if moisture is present, it will readily revert to its original carbonate form. This occurs when quicklime "air-slakes" and adsorbs CO.. from the air. Thus, quicklime is perishable and should be stored in dry, water-tight areas. Depending upon the type of kiln used and the physical structure of the stone, the size of the quicklime may range from sandlike granules to 8 in. lumps. However, pebble sizes ranging from 1/4 in. to 2 in. are the most common. Screened quicklime fines are also com¬pressed (pelletized) into 1 in. pellets. For some purposes ground or pulverized forms of quicklime are used, ranging from No. 10 mesh to dust. Generally a pebble of quicklime is about the same size as the pebble of limestone before calcination (perhaps shrinking slightly). A more stable form of lime is hydrated lime. This is obtained by adding water to quicklime, slaking it into a dry, fine, subsieve size white powder. Because its affinity for moisture has been satisfied, it is not vulnerable to further moisture like quicklime. However, it has the same strong affinity for CO_. The following reversible chemical reactions illustrate how hydrated lime when heated (or dehydrated) can revert to the original oxide form:

Jan 1, 1975

By E. V. Crane

A tremendous volume of the metal rolled annually into sheets strips and coil stock finds its way to a host of stamping and manufacturing plants which are the quantity production units of the country. Considerable in volume, too, are the rolled and extruded rods which go into forging and manufacturing plants for conversion into the same general line: those widely sold metallic necessities and luxuries of the household, the office, transportation, farming and building construction. Yet, in spite of its age and its importance, the stamping trade has been doing its "engineering" largely by trial and error. Its distinctive method is shearing out and plastically working metal to finished shape in a few quick strokes with high loads and expensive tools which are warranted only by large quantities to be produced. The principal operations have many features In common with rolling and wire-drawing methods. Combinations of stresses are diffcrent, however, and details of operations are infinite in variety. An engineering study of the subject begins with stress analysis, but must go back to metallurgy for its foundation. A grouping of pressed-metal working operations according to whether the metal is (1) sheared, (2) bent, (3) drawn or (4) squeezed has proved useful. All of these groups include instances of both hot and cold operations. For discussions of metal working properties, the division between hot and cold working is taken as the recrystallization range of temperature. This, of course, brings tin, lead and often zinc into the hot-work range at or near room temperature. The outstanding hot-working press field is in forging: particularly of brass; all of which is included in the squeezing group. Shearing Operations The shearing group of operations, including blanking, piercing, trimming, shaving, slitting, shearing, notching, parting and numerous variations and combinations of these enters once or more into the production schedule of practically every stamped or forged article. The transverse stress, set up in shearing, as shown in Fig. 1A, is a combination of an angular compressive thrust and a tensile stress which is also at an

Jan 1, 1931

1944. Walter Hull Aldridge New York, N. Y. 1946. Peter M Anderson Johannesburg, South Africa 1946. Charles Camsell Ottawa, Ont. Canada 1946. Charles Augustus Carlow Fife, Scotland 1949. Erie Victor Daveler New York, N. Y 1946. Cecil H. Desch London, England 1946. William Fraser London, England 1917. Herbert Hoover New York, N. Y. 1941. Daniel Cowan Jackling San Francisco, Calif. 1939. Henry Krumb New York, N. Y. 1942. Essington Lewis Melbourne, Vic., Australia 1921. C. McDermid London, England 1944. Walter C. Mendenhall Washington, D. C. 1942. Paul Dyer Merica New York, N. Y. 1938. A. M. Portevin Paris, France 1934. T. A. Rickard Victoria, B.C., Canada 1946. John R. Suman Houston, Texas 1946. Wen-Hao Wong Chungking, China

Jan 1, 1952

By Byron E. Eldred

(Pittsburg Meeting. March, 1010.) GENERALLY speaking, the practical study of combustion has been made mainly from the stand-point of the steam engineer. This. narrow view-point has left open a large field for scientific research on the application of combustion in other arts, where the conditions of heat-utilization are widely different from those presented in the steam-generator. The great economic importance of the boiler and the ease of measuring its performance, together with the comparative uniformity of conditions in the steam-generator, is, probably, quite largely responsible for the practical neglect of the study of the use of fuels in other arts save only on the basis of their thermal value. Yet these other arts show quite plainly that a thermal-value basis alone is Dot sufficient. For example, in burning lime, under ordinary conditions of firing, a cord of wood will do as much work as a ton of coal, though the latter affords more than twice the number of heat-units. Similar results are evidenced in burning brick, in the roasting of certain ores, in reheating billets, and in many other arts where heat is to be applied over extended areas to fragmental masses of more or less refractory materials. In these arts much is to be gained by a careful study of the application of the heating-agent in the form of the long flame, and in the production of the heat in contact with, or in direct proximity to, the object to be heated. Of necessity, in boiler-practice, combustion cannot be maintained in actual contact with, or in close proximity to, the object to be heated. Speaking in a general way, heat is imparted from burning bodies to things to be heated in two ways : directly, by radiation, and indirectly, by transfer of the sensible heat of hot gases by convection or contact; by conduction from the hot uses. Both ways are utilized in boiler-practice-directly, by

Jun 1, 1910

By C. E. Sims, G. A. Lillieqvist

The following presentation is more a summation of observations made and conclusions drawn over a period of three to four years than a report of experiments made with a definite objective. Tests were made, of course, to verify hypotheses, but the large mass of data was collected incidental to other work. Lack of space forbids the presentation of more than a few of those data. On the other hand, it is unfortunate that some of the most illustrative examples are not available. The work is admittedly incomplete but is presented in the hope that it will stimulate further work along a similar line. The answers to many of the questions left unanswered by this paper will be found only after long and painstaking study, such as is scarcely possible in a commercial laboratory where problems of immediate importance consume most of the time. It is also hoped that this study will in some measure throw light on some of the dark spots of steelmaking, and help to clarify some of the annoyingly vague references to "good practice." Only cast steel was studied and the conclusions apply to cast steel, but it is the authors' opinion that the quality of rolled or forged steel is largely dependent on the quality of the ingot, which is a casting. Although this discussion deals almost entirely with inclusions, it is important that the reader understand that only those natural inclusions which owe their origin to the solubility of certain materials in steel and to the chemical reactions of steelmaking are considered. Accidental inclusions, such as entrapped particles of slag, nozzle, runner, or mold arc outside its province and are not considered. Such accidental inclusions are always dangerous and should be carefully avoided. Relation between Ductility and Nonmetallic Inclusions In September, 1928, an acid electric furnace was put into operation at the Indiana Harbor plant of the American Steel Foundries. Following the usual practice, aluminum additions were made in order to obtain sound castings. Immediately the problem of low ductility arose. Previous to that time, only open-hearth steel was produced, and, aluminum being used rarely in that steel, there had been practically no trouble with low ductility in the lower carbon range.

Jan 1, 1932

By Evan Evans

WITH the expiration on April 30, 1941, of the agreement between the anthracite operators and the United Mine Workers of America, a new agreement was entered into, providing for a general wage increase of 7 1/2 per cent effective May 1, to be brought to a total of 10 per cent on Oct. 1. Contract rates were increased from the rates established under the agreement of September 1923, and hourly rates were raised above the agreement of May 1936 as modified from the eight-to seven-hour day in May 1937. The new rates are to be in force for the duration of the agreement, ending April 30, 1943.

Jan 1, 1942

By J. E. Ryan

TRONA, Calif., is a miniature urban community of some 3500 people, located on the northwest shore of dry Searles Lake in the extreme northwest corner of San Bernardino County, approximately 186 miles north and east of Los Angeles. Since it is situated on the Mojave Desert, a typically desert climate prevails with wide variations in temperature between day and night, extreme daytime summer heat, and cool to cold winters. Rainfall averages somewhat less than 4 in. per year, and dust storms are common. The rate of evaporation, .however, is great, amounting to 6 to 9 ft of water per year. The extremely low humidity makes the summer heat of 110°F tolerable with only a mild, temporary discomfort. Nature of Deposit During the periods when Searles Basin was flooded, the waters that passed through Indian Wells Valley spread out to form a broad, shallow lake providing, in effect, a settling basin for suspended sediment. The drainage into the deeper and more isolated Searles Basin thus was clarified to a great degree before concentration began. Today, the elevation of the dry surface of Searles Lake is 1618 ft, and the salt deposit measures 5x7 miles. At the eastern and northeastern margins of the main playa zone and just at the foot of the alluvial slope of sand and coarser wash from the Slate Range mountains, a rim of crusted salts rises a few feet above the level of the flat. The deposit is a saline efflorescence composed of salts that were presumably brought up with rising ground waters to be deposited at the surface by solar evaporation. This deposit consists chiefly of trona, and it is after this Trona Reef that the town Trona was named. Strip mining operations have been conducted in the past at infrequent intervals for the recovery of crude trona salts. The main focal point of interest in Searles Lake from a commercial standpoint is the main salt body located almost centrally in the basin. The exposed portion of this porous saline deposit covers approximately 12 sq miles and averages 71 ft deep. Its interstitial voids, which constitute 50 pct of the total volume, are permeated with a brine, which is in equilibrium with the soluble salt deposits. The brine is the raw material for the operations of the American Potash and Chemical Corp. plant at Trona, shown in Fig. 1. The soluble salt deposits are of interest for their potential values in future technologic development. The brine, which is stratified according to slight differences in density, stands usually within 6 in. of the surface of this exposed, firm, salt body. The surface is usually dry and will support the weight of heavy mobile units and drilling equipment. Occasionally, however, surface waters from the higher watersheds encroach upon the main salt body during infrequent periods of precipitation on the surrounding mountains. This water dissolves surface salt, becomes a dilute brine, and has been observed to stand as high as 18 in. above the salt surface when undisturbed. Windstorms will shift the water back and forth across the lake surface. The exposed salt body is surrounded by additional submerged areas of commercial soluble salt deposits covering some 20 sq miles, hidden from view by marginal playa mud. These vary in depth up to as much as 30 ft. Thus, the outline of exposed and submerged salt deposits of commercial value is estimated to cover a total area of 32 sq miles, which is roughly circular but slightly elongated from northwest to southeast. It has been estimated that each square mile contains about 100 million tons% f alkali salts. The results of drill borings in the past 15 years have brought to light the interesting fact that the main salt body lies superimposed on an impervious mud deposit from 10 to 15 ft thick containing relatively little soluble salt. Under this deposit lies a second soluble salt body 35 ft deep. The lower salt body is interspersed with numerous insoluble mud lenses and its composition is considerably different from that of the primary, or main salt deposit. Recent drill borings have not penetrated beyond 300 ft. They have, however, revealed that underlying the lower salt body, the mud sediments carry deposited minerals of trona, nahcolite, mirabilite and much less soluble carbonates or sulphates of calcium and/ or magnesium. This structure is shown in Fig. 2. Current Lake Survey Program Several hundred holes have been drilled in the deposit. However, to carry out a thorough and carefully correlated study of the composition of the soluble salts and other minerals in the dry lake basin, a drilling program was inaugurated recently and is now nearing completion. In this survey, pattern drill holes are sunk at regular lh-mile intervals to a depth of approximately 150 ft. Drilling equipment consists of a No. 51 C. P.

Jan 1, 1952

NEW MEMBERS The following list comprises the names of those persons who became members during the period Nov. 10 to Dec. 10, 1915: BARTH, ERNEST, Petroleum Geol Box 552, Tulsa, Okla. BEROLZHEIMER, D. D.,.Chemist; Librarian, Barrett Mfg. Co., 17 Battery Pl., New York, N. Y. BLIEK, PIERRE FRANCISCO, Mgr., Compania Minera de Oruro, Oruro, Bolivia, So. Amer. BLOCS, JAMES A., Met 1076 1st Ave., Salt Lake City, Utah. BULKLEY, RALPH G., Mine & Mill Supt.; The Montezuma Mines & Mills Co., Montezuma, Colo. BURRAGE, ALBERT CAMERON, JR., Met. Engr.; Director, 85 Ames Bldg., Boston, Mass. CABELL, CHARLES ARNOLD, Vice-Pres Carbon Coal Co., Carbon, W. Va. CHAPMAN, LEWIS CARL, Economic Geol Producer Oil Co., Houston, Tex. CHOFFEL, FLAVIEN AURELIEN, Mgr Ingersoll-Rand Co., Paris, France COY, HARLEY A., Mine Supt American Zinc Co., Mascot, Tenn. DITTMANN, C. 0. ADOLF, Cons. Engr., Beer, Sondheimer & Co., Inc., Santiago, Chile, So. Amer.

Jan 1, 1916

By E. J. Ripling

TUBES may be produced by a large number of forming processes, the most common of which will be discussed analytically in this paper. In no case will the stress analysis for any given tube producing process be derived formally for where such analyses are available, they may be referred to readily. Rather, emphasis will be placed on the interpretation of the theory of the different processes, few of which are developed to a state that will allow rigorous mathematical analyses, in an attempt to give a rational description of the effects of the different variables involved in each method. Tube producing methods can be divided into two groups: Those used to form shells, and those used to further work these shells into a shape more suitable for their final use. Among the first group are included roll piercing, extrusion and cupping for seamless shells, and bending with welding for welded tubes. The re-forming processes include sinking, drawing with a plug, and drawing with a rod. Only the plastic forming operations will be discussed here; other forming processes such as casting shells will not be considered. PRODUCTION OF SHELLS Shells for Seamless Tubing Piercing: The extremely important process of forming an axial hole in a billet by oblique rolling never has been analyzed satisfactorily, although a certain amount of experimental work relating to this process has been conducted. There are a number of factors that make piercing difficult to analyze; one of these is the fact that piercing is not a problem in plasticity, but one in fracturing, and the laws of fracturing are even less well understood than those of plasticity. If, however, it is assumed that fracturing occurs on a surface as a result of tensile stresses acting normal to this surface, piercing can be analyzed qualitatively by examining the stresses established in the oblique rolling process. To determine the origin of the tensile stresses that are thought to effect piercing, it will be necessary to know the angular relationships between the maximum stresses that are established in piercing. These angles quite frequently can be determined in a plastic deformation process by an examination of the deformed product. For example, consider the stresses established when a tensile test is conducted on a rectangular cross-sectional specimen of pearlitic steel. When stretched, this material first flows plastically, exhibiting the well-known yield jog on a stress-strain curve. The formation of the slip areas that give rise to the yield jog can be detected during the straining, since these flowed areas cause depressions on the specimen surfaces which can be seen if the surfaces are polished highly. The plastically strained areas also can be found after the specimen has been stretched to a strain not exceeding the yield jog, by sectioning the test piece and. etching these sections with Fry's etch. With this etchant, it is possible to dis-

Jan 1, 1951

Jan 1, 1910

By A. S. Richardson

THE conditions that make necessary the mechanical ventilation of the Butte mines of the Anaconda Copper Mining Co. are due to a number of causes, all of which are incidental to the depth at which mining operations are now carried on. The main object to be accomplished, of course, is the reduction of the temperature and humidity of the air in the working places. Ventilation fans, both surface and underground, have been used for many years, but increasing depth has made the problem much more difficult. Further improvement in both ventilation equipment and methods, therefore, became necessary; and it is the purpose of this paper to describe the work planned and done under the improvement program. The mines of the district have been frequently described in various technical publications, so a description is unnecessary here. From a mine-ventilation viewpoint, compared with coal-mine ventilation systems, the problem is complicated by the fact that the workings to be ventilated are situated on a large number of steeply dipping veins which frequently intersect and are faulted, and also by the fact that the extent, or existence, of orebodies is not definitely known in advance of actual development work. For these reasons ventilation work cannot be planned in advance of actual operations, nor can such regular systems of ventilation as are used in working the more uniform and continuous bodies of coal be developed. When operations are conducted at a normal rate, about 10,000 miners are employed on two shifts, so that about 5000 men will be underground at one time. But as ventilation is necessary to reduce high temperature and humidity due, mainly, to natural causes, the quantity of air per man per minute is not a governing consideration in determining ventilation requirements. Most important among the numerous sources of heat and humidity in the mines are : heat generated during decay of mine timber; heat and humidity given off by mine rock and water; heat generated by oxidation of sulfide minerals; heat given off by electrical equipment; heat generated by mine fires (in certain localities).

Jan 2, 1922

By Edward H. Bzirdick

THE territory under particular consideration in this article comprises portions of La Plata and Montezuma Counties, situated in the southwestern corner of Colorado, and around the base of the La Plata Mountains. (See Fig. 1.) In southeastern Utah and northeastern Arizona there are several mountain systems whose origin and structure are practically identical with the La Platas so that ore occurrences found in the latter can be hopefully looked for in the former. With this assumption, there is an area around the laccolithic ranges which offers promise for a successful exploration for gold ores. Ore occurrences of the Silverton, Telluride, Rico, or Ouray Districts will not be discussed, although in these areas the Mesozoic sediments are more or less involved within the ore-bearing complex. These have been intensively studied and developed. The idea is to set forth what my mining experience has been within the largely unaltered . Mesozoic horizon which remains around the extreme bases of the La Plazas. This, until recent years, has been almost entirely neglected by prospectors and operators and, so far as similar territory in Utah and Arizona is concerned, so remains.

Jan 1, 1934

By W. R. Bendy

GRINDING is a large and costly part of Portland cement manufacture. Prior to clinkering in the rotary kiln, raw materials are ground to a fineness of 80 to 90 pct passing 200 mesh. Then, after burning and cooling, the resulting clinker is ground to about 92 pct passing 325 mesh. In the cement industry the most favored method of grinding has always been by impact and attrition of a ball charge in a rotating mill. Other types of mills, in which materials are ground between die rings and rollers, or between die rings and large balls, are sometimes used for single-stage grinding and often for preliminary grinding followed by grinding in ball-type mills. Their efficiency is usually high, but maintenance and repair costs are high also, and the ball-type mill continues to be the most widely used. Together with 4 pct gypsum to retard setting time, the kiln run clinker—consisting of hard, semi-fused lumps that may have been crushed to — 1/2 in.—is ground to a Blaine surface area of 3000 sq cm per gram and about 92 pct passing 325 mesh. Approximately 32 kw-hr per ton, or 6 kw-hr per 376-1b barrel, are consumed in the grinding mills alone, not counting auxiliaries. Open Circuit Clinker Grinding: Many early clinker grinding plants employed two-stage, open circuit grinding. Comparatively short mills of large diameter, loaded with balls 4 in. and smaller, first reduced the clinker to 95 pct passing 14 mesh. Tube mills of smaller diameter and greater length, loaded with balls 11/4 in. and smaller, carried out the fine grinding operation. An early development was to assemble two or more stages of grinding in a single mill having two, three, or four compartments separated by division heads. There were difficulties in balancing the compartments, but compartment mills were popular in the 1920's because the layout was simple and there were no elevators and conveyors. Oversize Particles: Open circuit mills, whether separate ball and tube mills or compartment mills, always encountered the problem of tramp oversize in the product. A small percentage of clinker survived passage through the first grinding stage as particles—perhaps 1/16 in. diam—that were too large for the smaller balls in the following stages to reduce to —200 mesh. When the feed rate was lowered to reduce tramp oversize, there were serious losses in grinding efficiency. Many ingenious designs were perfected to incorporate perforated screen plates or wire mesh screens in the ball mills or in the first compartments of compartment mills. Their purpose was to prevent mate: rial passing out of the first stage until it was small

Jan 1, 1958

By Thomas T., Read

IT is difficult to judge how much influence the success attained during its first year, 1864-65, by the School of Mines at Columbia had on developments in education for the mineral industry elsewhere in the immediately subsequent years. The facts are as follows: 1. The Massachusetts Institute of Technology began giving instruction in February 1865, with a mining course included in its curriculum. 2. Early in 1865 the faculty of the Department of Science, Literature and the Arts of the University of Michigan requested permission from the Regents to establish "a course of study to be called the School of Mines . . . Also that the degree of Mining Engineering, be conferred on students who should complete the course of study prescribed in the same." A resolution authorizing this was adopted by the Regents on March 28, 1865. 3. Samuel Hooper endowed a Sturgis-Hooper professorship of geology at Harvard in 1865 with the intention of making it a nucleus of a new School of Practical Mining and Geology. 4. Yale appointed Alfred P. Rockwell professor of mining in 1865. 5. Lafayette College appointed Henry S. Osborn professor of mining and metallurgy in 1865. 6. Washington College (as Washington and Lee was then known), rising out of the ashes of Civil War destruction, made a fresh start in 1865, with Generalized as its president, and offered a mining course in the first catalogue thereafter published. 7. Lehigh University, founded in 1866, had a mining curriculum from its beginning. 8. Rensselaer Polytechnic began offering a curriculum in mining and metallurgical engineering in 1867. It would be natural to suppose that these events were a reaction, to the success of the school at Columbia, - and possibly they

Jan 1, 1941

By M. L. Holzworth, Philip R. Sperry, Paul A. Beck

INTRODUCTION THE basic work of Z. Jeffries1,2,3 has long ago established the main features of grain growth in the presence of a dispersed second phase. Working with sintered specimens of initially fine grained tungsten, to which various amounts of thoria have been added, Jeffries found that grain growth was inhabited, that is, practically prevented, up to a certain annealing temperature. When this temperature, which increased with the thoria content, was exceeded, extremely large grains developed abruptly from the fine grained matrix. Such a "coarsening temperature" was later found by Gross mann13,14 in certain types of steel, while Bain showed" that in other steels grain growth was gradual, without inhibition and abrupt coarsening. Later work16,17,18,19,21 demonstrated the connection between coarsening and aluminum additions. The viewpoint that the direct cause of inhibition and coarsening in aluminum killed steels is a fine dispersion of aluminum oxide21 appears to be held quite generally, although some doubts have been voiced even very recently.20 In steels with Ti additions the titanium carbide phase is considered responsible for the inhibition effects found.20 The coarsening temperature increases, with the titanium content. That coarsening may occur, as a result of certain heat treatments, even in low carbon rimmed sheet steel, was shown by Samuels,22 He also detected coarsening in a steel ingot of similar composition, after giving it the same heat treatment as that used by him for the sheet material, In this instance the identity of the inhibiting phase has not been determined, However, Tangerding found 23 that even the few small carbide particles, which occur in carbonyl iron, have a very marked inhibitive effect. As a result of an oxidizing anneal at 850°C, large grains begin to form at the surface of the carbonyl iron specimen, and gradually grow inward as the subsurface oxidation of the carbide particles progresses and eliminates the obstruction, The carbide particles can be removed also by annealing in hydrogen, with similar results. But if the oxidizing anneal of 10 hr at 850°C in air, is followed by annealing in hydrogen for 75 hr at the same temperature, grain growth is more spectacular; usually the whole specimen is transformed into a single crystal (approx. 1,5 cm X 5 cm). The reversed procedure, that is, hydrogen annealing followed by oxidizing annealing leads to smaller grains. Tangerding arrived at the logical conclusion that there must have been in his specimens some additional obstruction to grain growth resulting from a minor impurity, other than carbon. It seems likely that this obstruction was caused by an oxide formed during the oxidizing anneal and gradually reduced during the subsequent hydrogen-annealing. Other instances of grain growth inhibition of varying severity, associated with a dispersed second phase, have been described by several authors. Notable examples: lead with 0.06 pct Cu or Ni,24 cartridge brass with 0.12 pct Cr,25 or with up to 0.15

Jan 1, 1948

By J. Chupak, D. J. Salley, G. L. Simard

Radiotracers were demonstrated to be of considerable value in a study of the interaction of dithiophosphate with galena. The interaction had characteristics of both chemisorption and chemical reaction, being complex because of the nature of the galena surface. Sorption was rapid and markedly reversible, and flotation occurred at relatively small amounts of dithiophosphate sorbed.

Jan 1, 1950

By F. A. Schaufelberger

Early work on chemical precipitation of metals from metal salt solutions is reviewed. The chemistry and thermodynamics of precipitating copper, nickel, cobalt, and cadmium metals by reaction with hydrogen are discussed. Mechanisms of metal precipitation, nu-cleation, growth, and agglomeration are reviewed, as well as some solubility phenomena of cleation,gases and solids at elevated temperatures. Experimental data presented deal mainly with the reaction of copper sulfate solution with Hz. METAL can be recovered from a leach solution either indirectly by precipitation as a compound that is later reduced or directly by electrolysis, cementation, or chemical reduction, for example, with hydrogen. The widely used electrowinning processes suffer from the inefficiency of converting fuel to low voltage dc and from low current efficiency when complete recovery is attempted. With the batch hydrogen reduction methods outlined here, a unit of fuel converted to hydrogen in modern gas reform plants will make two to three times as much metal as can be obtained with electrolysis. With continuous hydrogen reduction, four to six times as much metal is obtained. Precipitation by reducing a metal salt solution with H, has been known for almost 100 years.' Commercial use of the process, however, awaited the research and development program initiated by Chemical Construction Corp. Within the last few years this program has brought about construction of commercial plants, listed on p. 701. Ideal hydrogen reduction will precipitate a pure metal from a solution obtained by commercial leaching methods at a rapid rate without excessive temperatures and pressures. The metal precipitate will be of desired size and density, less than a percent left in the vessel being deposited on the wetted parts. The present discussion will outline Chemical Construction Corp.'s early development program and will discuss the chemistry and mechanics of reducing copper, nickel, cobalt, and cadmium from solution by H2. Work on selective reduction of nickel from cobalt has been described earlier.2 The article is not concerned with precipitation of copper by disproportionation of cuprous solutions where yield is limited" to 50 pet.* It does not discuss use of gaseous reducing agents other than hydrogen, such as SCV which may lead to contamination with sulfur, or CO," which is considerably more expensive than hydrogen and produces a gaseous reaction product, CO2.† The article does not include use of other nongaseous reducing agents: which are far more expensive than CO. Also, notes on the history, engineering design, and performance of commercial plants have been given elsewhere." It will be shown that a pure metal can be precipitated by reduction with hydrogen from solutions obtained by commercial leaching methods when the solution cohposition is controlled and proper acidity, proper metal ion concentration through controlled complex formation and hydrolysis, and adequate agitation for suspension of metal and for transfer of reducing gas are maintained. Reasonable temperatures and pressures are used which are less excessive than those used by previous workers, although they are maintained at above equilibrium values because of process kinetics.' It has also been found necessary to induce nuclea-tion and to control growth and agglomeration in order to get a powder product of suitable physical properties. Review of the Literature Muller, Schlecht, and Schubardt of I. G. Farbenm claimed a successive reduction of silver, copper, nickel, cobalt, and zinc from ammoniacal solution by applying progressively higher temperatures and hydrogen pressures. Metals produced by this technique were not pure, since no attempt was made to adjust the solution composition between the different reductions. It is doubtful that the zinc product contained any metallic zinc. The major contribution to the literature" was made by the Ipatiews,12 who prepared platinum, iridium, copper, nickel, cobalt, lead, tin, arsenic. antimony, and bismuth at often extreme conditions, up to the critical temperature of water (373"C), at 1500 to 7500 psi, for as long as several days. Even cadmium and zinc were claimed to have been observed in trace quantities precipitated together with basic salts. In the early experiments solutions were not stirred. Extensive formation of oxides and basic salts occurred. probably long before sufficient hydrogen could be supplied in the unstirred liquid to decrease the metal concentration in solution by reduction. The importance of hydrogen pressure was

Jan 1, 1957

By Robert Glass Cleland

DURING the closing month of 1929, Walter Douglas found his health impaired by the strain of many difficult years of alternating prosperity and depression, and in April 1930 resigned the presidency of Phelps Dodge. Douglas was succeeded by Louis S. Cates. The choice broke a tradition that had been held inviolate for almost a hundred years. For the first time in its long history, the direction of the company's policies and operations was entrusted to a stranger without previous Phelps Dodge background, training, experience, or tradition. But the choice was wisely made. For a time at least, the path of Phelps Dodge was to run through rough and dubious ground, and no man in the United States was better qualified to blaze that trail than Louis Cates. After graduating from the Massachusetts Institute of Technology, Cates had served a rough and financially un- profitable apprenticeship at one of the century-old mining camps of Chihuahua, Mexico. Following his return to the United States and a brief interlude as assistant to the president of the National Steel and Wire Company, he had resumed his mining career, first as timekeeper, then as

Jan 1, 1952