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By Maurice Lacasse, Pierre Legast

GENERAL OUTLINE For more than one hundred years, asbestos ore has been mined on Les Mines d’Amiante Bell's property at Thetford-Mines , Quebec, Canada. In 1878, the first tons of fibre were produced. The mine operated as an open pit until 1951 at a yearly production of about 330 000 mt of ore. Since 1951, the mine has operated underground using a block caving method. The mine produced 725 000 mt per year until 1978, when the rate of production was increased to 1 100 000 mt. The ore was produced entirely fm the first lift on 650 level until 1976. Then, a second lift on 950 level was put into operation to replace production facilities fm the first lift which is now exhausted. Annual fibre production is 72 500 mt with grades £ran 3 to 7. The total work force is 600 people. The host rock is a peridotite partially serpentinized. The asbestos fibre seams occur as stockwork deposit structurally controlled by talcose shear zone. The geological rock formations are heavily jointed and have a wide range of competence. Asbestos ore bodies have an heterogeneous nature which des difficult geological interpretation. THE GRIZZLY METHODS A full gravity method was used on the first level where the caved ore was drawn from finger raises onto grizzly bars spaced at 480 mn. Oversize blocks were reduced by secondary blasting. The ore fell by gravity in- to the ore pass below the grizzly chamber and was loaded into 5.7 mt haulage cars through a 1.2 m wide chute. Access to the undercut drift was fm the grizzly drift through finger raises. The undercut trough was drilled and blasted in a 1.2 m interval ring sequence into a slot situated at the end of each panel. The undercut stope was emptied through the finger raises. The undercut retreated from South to North at blast interval determined by the finger raises spacing. Fig. 1 represents the various steps involved with the grizzly method. Extraction drift dimensions were opened 1.8 m wide x 2.4 m high with anchor rock bolts and wire mesh where safety required them during excavation. Grizzly chambers were excavated at 2.4 x 2.4 x 4.6 m long on a 7.6 x 7.6 m grid spacing. Ore passes with dimensions of 1.5 x 1.5 m were developed from the haulage drift. On the extraction level, headings were drilled with jacklegs and cleaned by slusher into ore passes to the haulage chutes. The support used in the grizzly chambers was square concrete structure with 150 mn H beam reinforcement. The H beam was partially buried in the concrete and had one free face to allow for difference frequency of blast vibration between concrete and steel. The supported brow of the chamber had an opening 1.5 x 2.1 m. Ore passes were ring concreted 150 mn thick without any reinforcement. A 24 MPa compressive strength concrete was pumped and poured in pre-assembled forms. Based on the success of this method on the first level, the same layout was repeated on the second level. With the start of undercutting on the second lift, signs of deterioration were noticed in extraction drifts. At first, there was great concern as the operators were confident that standard repair techniques could cope with such a situation. An intensive program of support repair and a reduction of draw resulted. The following method of repairs were used: 1) Steel square sets of 150 mn H beam at 0.6 m intervals were installed. 2) This was reduced later to 0.3 m interval and eventually to a skin to skin steel structure. 3) Yieldable arches were introduced spaced at 0.9 m intervals, linked laterally with 150 m. H beam. 4) The yieldable arches spacing was then reduced to 0.46 m and eventually installed skin to skin. However, this support was not successful.

Jan 1, 1981

By Harlowe Hardinqe

ABOUT three years ago a distinctive new type of crushing and grinding equipment, known as the Hadsel mill, was announced. A description appeared in the November, 1932, issue of this magazine. Any machine that would take run-of-mine ore and reduce it, in one operation, and at a reasonable cost, to a size suitable for metallurgical treatment was bound to attract much interest, as the original Hadsel mill did. The first commercial sizes were built with the drum supported by an overhung shaft and partly immersed in a tank. The drum carried inside and outside buckets to lift the ore, which was dropped as the drum revolved onto stationary breaker plates projecting into the drum from the opposite tank wall. The coarser material settled back into the inside buckets. Intermediate sizes were carried into the tank, and this material was scooped out by the outside buckets and deposited hack in the drum for further grinding. The fines were carried out of the mill with the wash water over an adjustable weir at one side of the tank.

Jan 1, 1935

By M. O. Holowaty, C. M. Squarcy

Blast furnaces are the tools of men, and it is men who have made them great. Here is presented the story of the Ironmakers-the men who first poured hot metal into what would someday be the sinews of a nation. W HEN the Jacobean merchant adventurers bade farewell to the first ship of colonists sailing for the new land, they instructed them to direct all their skill and energy to grow silk worms in Virginia. The adventurers felt sure that they could flood the market with highly priced and much desired goods like silk, sugar, tea, and indigo. They were also convinced that they would fill the needs of the mother country for iron. Early iron production in the colonies The merchants certainly had a wonderful imagination, for silk and indigo were just as exotic in Virginia as they were in England. The settlers found it more profitable to raise tobacco on the vast stretches of the free, fertile land. Thus the plans of settlers clashed with those of The Virginia Co.; and only point of agreement was the desire to produce iron. But, even there the motives of the settlers and those of The Virginia Co. of London were worlds apart. The settlers wanted to produce the tools badly needed in the colony, while the Company desired to cash in on the rising demand for iron which the home industry could not satisfy. Both the settlers and the Company lost no time trying to find iron ore. Locations of the early mines are not known. If, however, the reports of the Irishman, Francis Maguel, can be trusted, as early as 1609 a ship sailed for England with a load of 17 tons of crude iron which the East India Co. purchased at £ 4 per ton. The iron was of excellent quality and considered the best iron made of non-English ore that was ever purchased.

Jan 1, 1961

By Jay R. Burns

TWO magnesium sand-casting alloys are commonly favored in the United States. These are referred to as H and C alloys (Dow Chemical Co.) or 4Mz65 and AM260 alloys (American Magnesium Corporation). Both are of an aluminum-zinc-manganese type. H alloy contains 6 per cent aluminum and 3 per cent zinc and is characterized by relatively good toughness. C alloy contains 9 per cent aluminum and 2 per cent zinc and is employed where high yield strength and pressure tightness are required. Examination of magnesium castings poured in Europe and England,'J however, demonstrates that H and C alloys are replaced by .%8 and AZ~I, respectively. That is, A8 reprcsents a magnesiurn alloy having superior toughness while A291 is suitable for high yield strength and pressure-tight applications. The basic difference between the .Ameri-can and European alloys is that the foreign alloys employ a somewhat higher aluminum content and less zinc than is found in H and C alloys. The mechanical properties of the alloys, when divided into high and low-aluminum groups, are quite similar, as determined from separately cast foundry-control type test bars ,In this paper the decrease of mechanical properties caused by any given amount of microporosity is measured for H, C, A8, and AZ~I alloys. The relative susceptibility of each of the four alloys to microporosity is also determined. Typical mechanical properties and nominal chemical analyses are reported in Table I. The apparent similarities between the two alloys in each group have led to considerable discussion as to the relative merits of each of the compositions.2 Popular points for comparison between the alloys have been the relative susceptibility of each of the four alloys to microporosity6 and the effect of this microporosity on their mechanical properties. It is primarily intended, in this paper, to show the

Jan 1, 1946

By Jay R. Burns

TWO magnesium sand-casting alloys are commonly favored in the United States. These are referred to as H and C alloys (Dow Chemical Co.) or 4Mz65 and AM260 alloys (American Magnesium Corporation). Both are of an aluminum-zinc-manganese type. H alloy contains 6 per cent aluminum and 3 per cent zinc and is characterized by relatively good toughness. C alloy contains 9 per cent aluminum and 2 per cent zinc and is employed where high yield strength and pressure tightness are required. Examination of magnesium castings poured in Europe and England,'J however, demonstrates that H and C alloys are replaced by .%8 and AZ~I, respectively. That is, A8 reprcsents a magnesiurn alloy having superior toughness while A291 is suitable for high yield strength and pressure-tight applications. The basic difference between the .Ameri-can and European alloys is that the foreign alloys employ a somewhat higher aluminum content and less zinc than is found in H and C alloys. The mechanical properties of the alloys, when divided into high and low-aluminum groups, are quite similar, as determined from separately cast foundry-control type test bars ,In this paper the decrease of mechanical properties caused by any given amount of microporosity is measured for H, C, A8, and AZ~I alloys. The relative susceptibility of each of the four alloys to microporosity is also determined. Typical mechanical properties and nominal chemical analyses are reported in Table I. The apparent similarities between the two alloys in each group have led to considerable discussion as to the relative merits of each of the compositions.2 Popular points for comparison between the alloys have been the relative susceptibility of each of the four alloys to microporosity6 and the effect of this microporosity on their mechanical properties. It is primarily intended, in this paper, to show the

Jan 1, 1946

By B. D. Saklatwalla

FOR the proper understanding of the inclusion of certain elements in this review it seems necessary to state the meaning of "rare metals." Certain elements occur in deposits limited in extent or concentration, so that the extraction of the element in relation to market conditions becomes uneconomical. Others may occur in extensive and rich deposits but the reduction of the metal may be difficult and costly. Both these conditions effect the same result, namely, make the metal rare and costly. As an example of the first kind may be mentioned radium and of the second, calcium.

Jan 1, 1939

By ELLSIVOKTH DAGGETT

THE Berlin gold quartz mine is situated in Nye county, Nevada, on the west flank of the Shoshone range, about 40 miles south and 30 miles west from the town of Austin, the county-seat of Lander county. The distance from Austin is about 60 miles by stage-road. The outcrop of the vein, at the top of the incline-shaft, is situated just at the base of the mountain proper, almost exactly at the intersection of the mountain-side with the gravelly bench that slopes for about three-quarters of a mile to the flatter sage-brush plain, or desert valley, below. The -vein itself consists almost entirely of quartz, with perhaps 2 per cent. of sulphide of iron, copper, lead, zinc and antimony, and perhaps a trace of some of the compounds of tellurium with gold and silver, although none of the latter have been as yet positively identified. The relative proportion, by weight, of silver and gold in the ores, varies in different parts of the vein, from 12 silver for 1 of gold, to 7 silver for 1 of gold. The quartz vein-filling is usually frozen fast to the walls, and is very hard and compact, seldom showing the friable, fissured, or shelly structure often to be found in quartz veins. Comparatively little evidence of relative motion of one wall of the vein upon the other is to be found-a fact indicating that during the formation of the vein, and prior to the extensive movements herein described, little disturbance had taken place. No evidence whatever of metasomatic origin has been observed. On the other hand, occasional occurrences of comby structure, in which the axes of the quartz crystals are at right angles to the plane of the vein, rather indicate deposition from solution in a pre-existing fissure. Spurs, or branches, and small parallel veins, while not en-\

Mar 1, 1907

By A. W. Hahn

USE of gold leaf goes back to biblical and even to prehistoric times. Both gold and silver, as well as other metals, were employed in illustrating or illuminating manuscripts. The medieval monks also used bronze powders. Metals were subdivided as finely as possible by mechanical methods, or by granulation and then were pounded into finely divided flakes. Substances such as honey have also been employed, since early times to keep the flakes of metal apart during grinding. Stearic acid is a more modern agent used in flaking aluminum and other metals. Finely divided "blue powder" is a by-product in retorting zinc ores, and contains from 78 to 90 per cent of zinc metal. This has been used as a precipitant for precious metals in the cyanide process and for chemical reduction processes. The making of zinc dust by atomizing is a step well known in electrolytic zinc plants. The Thermit process of Goldschmidt also requires the use of finely divided aluminum.

Jan 1, 1937

By W. Smith, F. G. Rinker, D. Beggs

Early in 1965 the Surface Combustion Division of the Midland-Ross Corporation was awarded the contract to engineer and construct a taconite pelletizing plant for the National Steel pellet plant, administered by the Hanna Mining Co., near Keewatin, Minn. This plant, which will have an annual capacity of 2,400,000 long tons, will produce pellets from magnetite concentrate using a new process developed through a joint research program by Midland-Ross, Hanna Mining, and the National Steel Corp. The work that culminated in the decision to construct this plant is the result of a research program for the development of the Midland-Ross heat fast process for the production of prereduced or metallized pellets. PELLETIZING PROCESS There are many acceptable methods for producing oxide pellets from ground iron ores and concentrates, and all of these give an acceptable product for blast furnace utilization. The vertical shaft furnace, the traveling grate, and the grate-kiln have been installed in many pelletizing plants in the northern hemisphere; therefore, the acceptance of these methods and the problems associated with them are well understood. However, this research project investigated a method for improving upon these processes to produce a high quality oxide pellet at a low operating cost.

Jan 9, 1966

Discussion of the paper of W. R. Shimer and F. O. Kichline, presented at the New York Meeting, October, 1913, and printed in Bulletin No. 81, September, 1913, pp. 2361 to 2377. ALLERTON S. CUSHMAN,* Washington, D. C.:-I have been much interested in Mr. Shimer's valuable contribution. The apparent fact that the oxides of certain metals which are not reduced by hydrogen per se, are reducible when the oxides are dissolved in iron in small quantity, is brought out for the first time, and is worthy of the careful attention of investigators. The Ledebur method has been subjected to considerable criticism, owing to the alleged fact that it did not measure the oxygen combined with impurities. Personally I have found the method extremely helpful in spite of the minute quantities of oxygen with which it deals. Mr. Shinier points out that the highest oxygen he obtained by over-blowing was 0.074 per cent., while the minimum quantity in a properly finished steel was in the neighborhood of 0.02 per cent. The Ledebur method is used as a constant check on the quality of heats made in practice under my direction. In dealing with a very pure commercial iron, we should expect to find and would find difficulty in galvanizing sheets made from a heat running 0.07 per cent. oxygen. In fact, we do not like to have the oxygen rise above 0.03 per cent. I am inclined to agree with the author that excessive oxygen leaves a bath of metal in a very short time, but nevertheless I believe it takes only a very little combined oxygen to begin to make its presence felt in the pickling and galvanizing department, when sheet metal is the product manufactured. As Mr. Shimer points out, the higher the carbon, the lower the oxygen danger, and it is partly for this reason that the manufacture of carbon-free metal in the open-hearth furnace has to be so very carefully watched and controlled from the furnace through to the finished product. It is quite possible that, there is a critical temperature of dissociation between iron and oxygen, although the critical points may vary in baths of different carbon content. Unfortunately, the accurate determination of the temperature of a molten bath at the time of pouring or teeming is a very difficult matter. For a long time I have been wishing that there were some reliable data which would indicate the effect of the tem-

Jan 12, 1913

By Lester F. Engle

Books have been written, complex charts drawn, great batches of punched cards handled by ever increasing numbers of computers, and innumerable meetings held-all for the purpose of making effective the ultimate objective of new, revised or improved process facilities. It is to the credit of management, engineers, and others that in the vast majority of cases, the outcome of their work has been technically sound and economically rewarding. There is a way, however, to insure even better results.

Jan 5, 1966

By Moshe Sheinkin, Burke O. Trafton

This paper describes the use of a computer in analyzing the expected return on a mining venture. The computer program is designed to incorporate all aspects of a mining project, including the mine, mill, smelter, and refinery. Data input may consist of the operating variables in each phase such as the mining rate, grades, reserves at the mine, and the technical operating characteristics of the mine, mill, smelter, and refinery. Detailed tax computations are shown for a domestic operating company, for a foreign company and for a foreign subsidiary. In addition, the use of the various options that are available such as expense write-offs or deferments to create tax credits during preproduction years are considered, and its effect on the DCF. The program is also constructed to accommodate changes in metal prices, and escalation of capital requirements and operating costs. Output consists of profit and loss statements for entire projects using different methods of depreciation, cash flows, discounted cash flows, net present value and returns on investment. Returns on investment are computed for equity investment, total investment, and total investment less tax credits. Allowances are made for bank and guaranteed loans. Additional financial statements can be made for the following: a) A mine-mill segment with a concentrate selling schedule b) A mine-mill-smelter complex with a smelter product selling schedule c) Profitability of the smelter separately d) Profitability of the refinery separately

Jan 1, 1969

By W. D. BRENNAN

FOR a considerable number of years past, there has been a shortage of experienced coal miners at the coal mine of the Phelps-Dodge Corp. This is probably due, to some extent, to the mines being so far south of the main western coal producing regions, so that experienced men secure employment before reaching this point. These mines are at Dawson, New Mexico, which is in Colfax County, near the Colorado line. The district is known as the Raton field, and the seam being worked is known as the Raton or Blossburg seam. The mines operated are Nos. 1 to 6, 8 and 9. The daily out- put at the present time, with restricted operations, is about 4000 tons, but the daily capacity is about 5500 tons. The mines are so grouped that the coal is dumped over four tipples. The mines are about twenty-five years old and extend as much as three miles under ground; they are all drift openings, with trolley, storage battery, and mule haulage. At the same time that the shortage of miners existed there was a surplus of common labor seeking employment. We learned that the Copper Queen. Branch of Phelps Dodge Corp. conducted a training school in one of its mines which had worked out very satisfactorily, and thus gained the idea of attempting such a school in the coal mines at Dawson.

Jan 1, 1929

By Walter R. Hibbard, George H. Eichelman, William P. Saunders

INTEREST in the various products of the austenite eutectoid transformation in iron-carbon alloys, particularly as produced by the isothermal sub-critical techniques introduced by Davenport and Bain,1 has resulted in the application of similar heat treatments to other eutectoid transformations. Studies2.3.4 of the beta copper-aluminum alloy eutectoid transformation revealed microstructures very similar to those found in iron-carbon alloys. Investigations5,6 of the kappa phase in the copper-silicon alloy system have established the eutectoid type transformation of this phase into terminal alpha and intermediate gamma phases. This transformation has been reported' as forming a eutectoid type structure in a very sluggish manner by a long time isothermal treatment. The purpose of the present investigation is to study the products of the kappa eutectoid transformation as affected by transformation temperatures by means of microscopic and hardness methods. PREPARATION OF ALLOYS The copper-silicon alloy equilibrium diagram is shown in Fig I. The kappa field converges to a minimum silicon solubility at the eutectoid composition and all other completely kappa alloys are hypereutectoid. Thus, kappa decomposition involves first the proeutectoid precipitation of gamma, followed by the eutectoid transformation of a lower silicon content kappa (5.2 pct). Smith5 has indicated that alloys containing between 5.4 and 5.7 pct silicon could be hot rolled, but that the latter composition was desirable in order to permit a wider kappa temperature range. The alloy was prepared by adding Baker's commercially pure silicon to an ingot of copper-silicon alloy containing 2.34 pct silicon remaining from the investigation of Brick, Martin and Angier.7 Following the casting techniques of Krynitsky, Saunders and Stern,8 the ingot was melted under a heavy layer of dried charcoal in a clay-graphite crucible in a gas-fired pot furnace. Small lumps of silicon were held under the melt surface with a graphite rod. After the silicon had dissolved, the alloy was chill-cast and then remelted without a cover, stirred thoroughly, skimmed and poured into a preheated cast iron mold. The cast microstructure is shown in Fig 2. The casting, 10 X 4 X ¾ in., was annealed at 750°C for 21 brand furnace cooled. About 1/16 in. was milled from all surfaces. The plate was cut in half longitudinally and the bottom half analyzed by A.S.T.M. methods.9 The composition by weight was as follows: copper 94.24 pct, silicon 5.56 pct, iron 0.11 pct.

Jan 1, 1948

By C. J. Ramsburg

THE construction and operation of by-product coke-oven plants in America are essential to strong national defense and of the greatest importance to many widely diversified undertakings as well as to safety and health. CARBONIZATION PROCESS Coal used under a boiler or in a locomotive is consumed by combustion. Coal used in a by-product oven is distilled or carbonized, meaning that heat is applied to the coal, out of contact with air, causing a distillation that removes the volatile matter in the coal in the form of gas and vapor, leaving coke as a final product. From the gas and vapor distilled from the coal, many valuable substances can be secured, known as by-products. Hence the name "by-product oven." The simplest example of this principle can be shown by means of an ordinary clay pipe. If powdered coal is placed in the bowl of the pipe, the opening of the bowl is plugged with clay, and the bowl placed in a flame, the bowl will become hot, transferring the heat through the wall of the bowl to the coal within. When this coal attains a temperature of about 950°F., gas will begin to pour out of the pipe stem, and this gas may be lighted. A black liquid also will exude from the stem of the pipe. This is tar mixed with certain other products. What remains in the bowl after distillation is coke. A coke oven corresponds to the bowl of the pipe. A modern oven of the latest type is a refractory brick chamber approximately 42 ft. long and 14 ft. high, averaging 18 in. in width. The oven is filled with coal through closable charging holes in the oven top. Each end of the oven consists entirely of a self-sealing door, the removal of which permits the finished coke to be discharged by means of a power-operated pusher machine. The ovens are built in batteries, and the heating is effected by gas burned in vertical flues in the oven walls, each set of flues heating the walls of two adjacent ovens. Such ovens carbonize a charge of approximately 18 tons of coal in 18 hr., or have a daily throughput of 24 tons per oven, producing about I 7 tons of coke. In times of need, the output may be increased by raising the temperature of flues, thus shortening the coking time. There is one great essential difference in principle between distillation in a clay pipe and in a coke oven. In the 18-in. oven, the distillation proceeds from two parallel walls held at a high temperature (over 2000°F.) and instead of all the coal being heated at once, the distillation is a progressive one creeping inward. The average travel of this heating is 1/2 in. per hour from each vertical wall, and as the volatile products are formed progressively they must push away from the interior toward the wall through the previously formed hot coke, then up the walls and over the top of the coal charge, finally escaping through the outlet pipe. This results in a cracking of the components into many different and valuable substances not formed when the carbonizing temperature is low.

Jan 1, 1942

By W. Geo. Waring

THE growing need of better methods for the recovery of zinc and other elements from complex sulfide ores has suggested an inquiry respecting a possible group separation of the elements by the aid of volatilization at more or less elevated temperatures. It 'is evident that if the zinc content of such ores can be completely separated, for instance, as pure oxide, by a volatilization 'method, there should be no difficulty in recovering the other elements by smelting and refining. Zinc burning" as applied to zinkiferous ores has advanced but little in practice since the invention of the wetherill grate-furnace process in 1852, as may be seen by reference to papers on the subject.' In other words the thermochemical reaction employed in effecting the volatilization of the zinc is essentially one of reduction by means of carbon, whether the ores treated contain their zinc in an oxidized form, or as the sulfide. The zinc vapors, liberated from the ores at a temperature above that required for the reduction of ZnO by C (about ,1100° C.) or for the volatilization of ZnS per se, (about' 1300°-1400° C.) are subsequently burned to ZnO or to ZnO + SOz, by contact with' atmospheric ,oxygen in the upper or posterior parts of the furnace chamber, or in a so-called "combustion chamber" after leaving the .furnace proper.

Jan 1, 1925

By Franc R. Joubin, D. H. James

Uranium exploration in the North Shore area of Lake Huron goes back to 1847 when J. L. LeConte, a distinguished American geologist, identified a pitchblende-like mineral which he called coracite from specimens sent from a locality north of Sault Ste. Marie. In 1948 a search for the LeConte occurrence resulted in discovery of the Camray field, some 70 miles north of Sault Ste. Marie. Prospecting the Camray field yielded about 30 pitchblende occurrences spread over approximately 200 sq miles. Almost without exception these discoveries consisted of narrow, short, pitchblende-filled fractures, within or along the contacts of diabase dykes cutting pre-Cambrian Archean granite and gneiss. Eight discoveries were diamond drilled and three were explored underground, but none proved to be of economic value. Uranium prospecting at this time spread far afield, and it was in 1949 that radioactive conglomerate was discovered in Long Township of the Algoma district midway between and 90 miles from Sault Ste. Marie and Sudbury. F. Joubin examined this discovery at that time but could not interest capital in its development.

Jun 1, 1956

By G. L. Kehl, Emilo Jaraiz F., J. S. Brett

The transformation of eutectoid beryllium bronze has been quantitatively investigated at 550° and 592°C, the temperature region where the products of p decomposition are a fine lamellar eutectoid and a coarse lamellar aggregate which replaces the fine eutectoid with prolonged annealing. Metallographic evidence indicates that the coarse lamellar aggregate forms preferentially in the most densely lamellated regions of the fine eutectoid and favors the hypothesis that the development of the coarse lamellar aggregate in the fine eutectoid is due to the occurence of a cellular segregation reaction. WHEN eutectoid beryllium bronze (Cu-94 pct, Be-6 pct) is isothermally transformed at high temperatures in the and y region after quenching from the fl field, the principal initial decomposition process is G one of growth of approximately spherical nodules composed of a number of lamellar colonies of the a and y phases. After the initial reaction has proceeded substantially or completely, depending on the transformation temperature, a second reaction occurs wherein the fine lamellar eutectoid is replaced by a coarser lamellar aggregate composed of the same oand yphases.' This reaction is not simply a spheroidization of the initial fine eutectoid but the nucleation and growth of a coarser, structurally different, and more stable distribution of the @and yphases. Fig. 1 illustrates the replacement of the initial fine lamellar structure by a coarse lamellar aggregate. The a phase is the dark mottled constituent; the light constituent the y phase. The phase diagram for the copper-rich end of the Cu-Be system2 is shown in Fig. 2. The a phase has the face-centered cubic structure characteristic of copper-rich solid solutions. The B phase is a disordered body-centered cubic structure, while the y phase is body-centered cubic, ordered (CsC1, B2 type). A. viswanathanS investigating Debye patterns of Cu-6 pct Be discovered that a transitory phase appeared on very rapid quenching from the /3 region which was absent when the quenching velocity was moderate. The phase could be assigned a body-centtred cubic structure with a lattice parameter of 2.876. Tempering at 100°C for 2 hr after quenching resulted in complete disappearance of the phase. The work of Fillnow and Mack' is the only previously published study of the isothermal transformation of eutectoid beryllium bronze. Their study elucidated the nature of decomposition at various subcritical temperatures in an exploratory fashion. The purpose of the research reported in this paper was principally to obtain quantitative information on the isothermal decomposition of the fl phase and to clarify the relationships existing between the fine lamellar eutectoid and the coarse lamellar aggregate. EXPERIMENTAL PROCEDURE The material used in this investigation was an almost eutectoid Cu-Be alloy bar furnished by D.J. Mack. The alloy had been melted under a protective carbon cover and centrigugally cast into a graphite mold preheated to 490 "C. Segregation was minimized by violent agitation during melting and pouring. The analysis of the casting was 93.85 pct Cu, 5.60 pet Be with traces of Si, Mg, Mn, Co, and Al. To determine the minimum soaking time necessary to insure specimen homogeneity, a number of specimens were held in the P region at 788OC for times fron 1 min to 12 hr and isothermally transformed at 550°C. Specimens betatized less than 12 min exhibited partial transformation at times shorter

Jan 1, 1961

By Robert S. Schecter, Mark P. Walsh, Michael J. Humenick

In recent years in situ leach mining has emerged as a viable technology for the recovery of uranium from strata in South Texas which contain relatively low concentrations of uranium ore. Because the ore bodies lie within ground-water aquifers, a significant determinant in the economics is the requirement that such aquifers be protected from contamination. Since ammonia is one of the constituents of the leach solutions now being field tested, one environmental problem to be resolved is the removal of ammonia at the end of mining. A second related question is the fate of the ammonia which is not removed by the restoration procedure. This paper considers the displacement and migration of ammonium in a flowing electrolyte with concomitant ion exchange. The ion exchange is an important feature since, during the solution mining phase, ammonium saturates the mineral exchange sites and must be removed from these sites. A mathematical model is used to simulate this process and the model is tested against the results of laborator.y experiments. It is found that the simulations are adequate if an appropriate selection of parameters is made. The model is then used to investigate the effect of cation composition and concentration of the restoration medium as well as dispersion on the overall effectiveness of the process. It is concluded that increasing the concentration of monovalent ions in a solution containing a mixture of both monovalent and divalent ions decreases the adsorption selectivity of the divalent ions with respect to all monovalent ions including ammonium. Thus increasing the ionic concentration of a restoration fluid by increasing the concentration of a nonselectively adsorbed (with respect to ammonium) ion may have a very limited benefit.

Jan 1, 1979

By Allan Martin, R. A. Swalin

Diffusion rates of manganese, aluminum, titanium, and tungsten in nickel were measured at temperatures between 1100° and 1300°C. Activation energies, Q, and values of the frequency factor, Do, were calculated for each system. Values of Q were found to be within 15 pet of that for self-diffusion of nickel in agreement with present theories of diffusion. ONE of the most interesting problems in diffusion concerns factors governing the order of diffusion coefficients of various solutes in a common solvent metal at low solute concentrations. An early suggestion by Rhines and Mehl' was that diffusion coefficients might each approach that of the self-diffusion coefficient of the solvent itself. Later Thomas and Birchenall' pointed out correlations between the order of the diffusion coefficients and the freezing point depressions of the solvent by the various solutes. Other correlations have been sought. To settle this question it seems likely that much more data will be needed and, in particular, data collected at low solute concentrations. This type can be obtained by special analytical techniques as well as by use of radioactive tracers. The following study was made of diffusion of manganese, aluminum, titanium, and tungsten in a common solvent, nickel, at relatively low solute concentrations: 1—Production of alloys of nickel with manganese, aluminum, titanium. and tungsten at concentrations of the order of 1 atomic pet. 2—Use of pressure-welded diffusion couples in cylindrical form. 3—Diffusion anneals in the temperature range of 1100" to 1300°C. 4—Lathe sectioning of the diffused couples. 5—Spectrophotometric analyses of lathe turnings for the solute being studied. 6—Calculation of the diffusion coefficient for each of the solutes as a function of temperature. 7—Interpretation of results with current theories of diffusion. Experimental Work Materials—Two types of nickel were used in this research. The grade designated as Vacuum melted Mond nickel was used for all diffusion systems except the Mn-Ni system for which the Vacuum melted electrolytic nickel was used. Analyses of the two grades are given in Table I. The manganese used in making alloys was 99.9 + pet pure, aluminum 99.99 pet pure, titanium 99.9 pet pure, and tungsten of C.P. grade powder. Alloys used in this investigation were prepared by melting in vacuo or under a low pressure of argon. After melting, all heats except those of nickel-manganese were poured into a cylindrical copper mold 3 in. long and 1 in. ID. In the case of nickel-manganese, the alloys were solidified in the melting crucible. For nickel-aluminum heats alumina crucibles were used and for all other heats, zirconia crucibles.

Jan 1, 1957