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By Norman Hedley, George Barsky, S. J. Sawinson

The cyanidation of precious-metal ores is a complex chemical process. Numerous reactions occur, some of which cause an undesired consumption of alkali and of cyanide. A knowledge of these reactions, their products, and the factors that influence the rates at which they proceed should be of value in working out the most economical conditions for cyanidation; but at present, much of this knowledge is lacking. This paper is confined to a study of some of the fundamentals of cyanidation. At the start of such an investigation it is necessary to simplify the problem under consideration by eliminating as many variables as possible. The results are then, of course, not immediately applicable to practice, but it is hoped in further work to round out the information and thereby make it of more practical value. For convenience in presentation, the paper has been divided into two parts, one devoted to a study of the reaction between cyanide and gold or silver, the other to a consideration of the factors that determine the rate of dissolution. I. REACTIONS INVOLVED IN DISSOLUTION OF GOLD AND SILVER IN DILUTE CYANIDE SOLUTIONS Ever since the cyanide process for gold and silver extraction was introduced there has been discussion of the equation representing the reactions involved. In undertaking a detailed study of these factors, it was felt that the most logical first step was to determine, if possible, what reactions could theoretically take place when gold and sill-er are dissolved by dilute cyanide solutions. It is possible to determine whether or not a given reaction will theoretically take place by calculating the free energy of the reaction. This free-energy value for any given reaction is the algebraic sum of the free energies of formation of each of the reactants and products, and, if these values are known, the calculation is simple. (A chemical change always involves an energy change and the amount of energy change involved is the factor determining whether a given reaction will take place or how far it will go. In chemistry we consider what is known as the "free energy"; that is, the maximum amount of energy that can be utilized as

Jan 1, 1935

By A. W. Gauger

SMELTING of iron ore, manufacture of steel, and the fabrication of ferrous metal products are all processes that require energy. Charcoal was adequate, to supply this energy for the relatively simple processes of the early iron-masters. In the fourth decade of the nineteenth century, anthracite and bituminous coal and later coke supplanted charcoal for the smelting of iron. So far as the chemical phases of the process were concerned, charcoal was an ideal iron-furnace fuel. It had practically no sulphur, and its ash, besides being low in quantity, consisted chiefly of lime and alkalies, thus supplying a part of the flux required for smelting the ore. The ash of coal and coke on the other hand, being largely silica, had itself to be fluxed with bases added to the charge. Physically, however, coke proved to have many advantages over charcoal, which could not be used in the furnaces of today. The chief reason, however, for the change from charcoal to coke was the impossibility of maintaining an adequate wood supply.

Jan 1, 1941

By AIME AIME

DESPITE the fact that its membership is spread over every continent of the globe, the Petroleum Division was able to report a very substantial attendance at its meetings. Careful planning on the part of its chairman, J. B. Urnpleby, and his associates resulted in the presentation of a program that was of timely interest -and led to discussions that will unquestionably prove to be of major value to the petroleum engineer and to the oil industry in general. Scheduling of meetings so as to avoid all conflicts made it possible to obtain a higher average attendance at the several sessions* than in previous years, and gave everyone a chance to hear all of the papers that he was interested in. The chairmen of the various meetings are to be congratulated especially for their skill in handling them so that at .no time was there the least indication of lagging interest.

Jan 1, 1930

WITH the economic situation of the world what it is, we may expect important events in every month of 1922, and January showed us some-what of the nature of things that will happen. The Germans announced their inability to meet in full the reparation payments that were due Jan. 15. The Su-preme Council arranged a plan for them to pay some thing on account every 10 days, and called a conference at Cannes to talk things over. While this conference was in progress Premier Briand resigned and was suc-ceeded by Poincaré. This emphasized the growing differences between British and French policies and interests. The French want to exact the utmost from the Germans; so do the British. The latter think, however, that the French aims will so cripple the Germans that they can not work properly and hence can not trade. Great Britain, with a huge unemploy-ment problem, must have trade. The French thought that Briand was unduly deferring to the British and withdrew their support of him. The other important political developments of the month in Europe were the establishment of the Irish Free State, relieving the British of the vexatious Irish question; and the growing tendency to recognize the Soviet government of Russia and admit its representa-tives into international conferences. In the United States the great political event was the establishment of the dominance of the agricultural bloc in the Senate, which implies the passage of agrarian legislation that will probably be unwise. Economically, there was no progress in the United States. If anything there was probably some reces-sion in the physical volume of business. There were some further reductions of wages, but these were irregular, geographically, and moderate in amount. The great unionized trades maintained the jam. Events of great importance were the formal demand of the anthracite coal miners for increased wages on April 1 and the declaration of the bituminous coal miners that they would resist a reduction at that time. The attitude of these groups is believed to presage labor troubles in the spring. In the metal markets affairs were dull during Janu-ary, but prices were generally firm, save for a little further weakening in iron and steel. In the matter of production, however, there was some quickening of activity, especially in copper, zinc and iron.

Jan 2, 1922

“The mining industry can do more to alleviate world poverty, hunger and human misery, more to close the widening gap between advanced and developing nations and more to achieve international peace and understanding than any other single force in the world," Charles W. Court, Minister for Industrial Development, Western Australia, told the American Mining Congress audience at the opening session of the 1969 Mining Convention, October 19-22, San Francisco. Australia, he pointed out, is a shining example. In 1971, 60% of U.S. mining investment overseas will go to Australia and other parts of Oceania, an increase of 42% over a year ago. Australia has capitalized on world needs, its own rich resources and good investment climate. Developing nations can and should do the same, but they mix emotion with nationalism, often frightening away foreign investment which could breathe life into dormant and backward areas, said Court.

Jan 12, 1969

department, first as a practical miner, next. as rodman on the survey corps, of which he soon became chief, then draftsman and mining engineer in the company's office. In January, 1916, he was promoted to the position of district engineer in charge of mining engineering work. He became a member of this Institute in September, 1917. Captain Ba.llamy's military experience began at the same time as his engineering practice. He was a charter member of Company A, Engineers, N. G. P., which was organized ten years ago. He saw service on the Mexican border as First Lieutenant of this Company, and remained in that position until November, 1916. In July, 1917, he was again called into service and was sent to Camp Hancock, Ga., with the 103d Regiment of Engineers. Before joining this regiment he attended a school for officers at Fort Sill, Okla., where he received special training in field fortifications. In December, 1917, he was commissioned Topographical Captain on the Regimental Staff, and in April, 1918, preceded his regiment by about six weeks to France, where he again attended an officers' training school. He rejoined his regiment on July 15, near Chateau Thierry and was killed near Fismes on Aug. 9, 1918. Lieutenant Martin F. Bowles Martin F. BOWleS, born Apr. 25, 1893, at Bonne Terre, Mo., and graduated from the Neodesha, Kans., High School, had finished all but one month of a four-year course in metallurgical engineering at the Missouri School of Mines, Rolla, Mo., when on May 12, 1917, he entered the first Officers' Training Camp at Fort Riley, Kans. At the close of the training period, he was commissioned a Sccond Lieutenant and assigned to Co. B, 355th Infantry, 89th Division, and stationed at Camp Funston. He left this camp with his company on May 21, 1918, and sailed from an eastern port on June 4, ayriving in England on June 15, 1918. After a short stay at a rest camp there, he proceeded to France. On August 14, he wrote that he was with Battalion Headquarters as Gout Officer, 1st Battalion, 355th Infantry, 89th Division. The last letter received from him, dated September 2, was written in his dugout and contained the following: "Here it is 2.45 a. M. Sitting in a dugout waiting for some patrols to report back in, I am writing this by the light of two candles." He was killed in action on the night of Sept. 3, 1918. The letter of notifi-

Jan 1, 1920

By E. J. Schmitz

This novel safety-lamp, which was first introduced in some of the German coal-mines in 1882, at once attracted general attention in the coal-districts of Europe. Objections which arose during the early stages of its use at the mines have gradually died away with the increase of experience in handling the lamp 011 the part of the miners, and the continual efforts to perfect it on the part of its inventors. Wolf's lamp has rapidly surpassed all its rivals, and has already a greater distribution on the Continent than any one of its older sisters. In the course of two and a half years, the manufacturers have sold 25,000 of the lamps, besides remodelling several thousand rapeseed-oil lamps. This great success, which of itself speaks loudly enough as to the superiority of the Wolf benzine-lamp, is corroborated by both official and private reports, which all agree in pronouncing this lamp the best yet brought forward. It was described in a paper by Mr. Eugene B. Wilson, read at the Chicago meeting of the Institute, in May, 1881,* in which its salient merits were briefly but clearly indicated. Every previous improvement of the original Davy lamp has been directed to one or more of the following main points: 1. Light of greater and more uniform intensity. 2. Freedom from smoke or soot, which clogs the gauze and other parts of the lamp. 3. A greater safety and sensitiveness in the presence of firedamp. 4. An illuminating material which, satisfying the foregoing conditions, should be also cheap. 5. A lock which could not be opened in the mine by the miner. 6. An arrangement for lighting without opening the lamp. 7. An arrangement for changing the size of the flame in the closed lamp, to supersede the picker, the danger from which is explained in Mr. Wilson's paper, already cited. It may safely be said that wolf's lamp was the first to secure all these objects. The adoption of benzine instead of rapeseed-oil (previonsly the best illuminant) has completely satisfied conditions 1, 2, 3, and 4. Benzine gives a much clearer, stronger, and more uni-

Jan 1, 1886

By H. R. Aldrich

This paper is not a treatise on the theory and practice of magnetic surveying. It presents a diagram upon which have been plotted observations taken with the simplest form of magnetic instrument, the lowly dip needle, over a large area astride the Lake Superior syncline of northern wisconsin. The exposures of the underlying formations are not sufficiently great in number nor fortunate in distribution to have provided the fuller understanding of the geology which has been secured by the use of the magnetic observations as an auxiliary tool or accessory in the hands of the geologist. The diagram (Fig. 2) in large part speaks for itself if studied in connection with the geological map (Fig. 1) for which it is the main control. It is presented to demonstrate the extent to which the use of such methods may aid in the solution of geological problems in a covered country. The diagram is probably unique in assembling the expression of such a wide range of formations, affected by so wide a range of secondary processes, and deformed by so many different structures in terms of magnetic variation. Few geologists outside of the Lake Superior country have had any first-hand experience in the taking of magnetic observations and the interpretation of the results in terms of geological conditions; nor have the Lake Superior men gone with the methods far afield from the mere tracing of iron formations. In more recent years the oil companies have gone heavily into investments in magnetometers, balances, and dip needles in the quest of concealed structural anomalies which are the favorable loci of petroleum accumulation. But these geophysicists come back from the fields with their collections of observations facing the question of interpreting the geological meaning of their magnetic anomalies. It is considered probable therefore, and certainly it is the hope of the writer, that the appended charts, or magnographs, which show how character of the country rock and its changes, structural strike and dip and their changes, depth of burial and its variation, contact metamorphic

Jan 1, 1929

By M. S. NORTH

IT may be a far cry from the days of the old horse whim, and it is relatively a long way back to hand production in factories. Modern machinery has made possible deep shaft-sinking, newer methods have increased the recovery of mineral. Technically, excavating and ore dressing have advanced as has mass production and its many ramifications in the manufacture of commercial product. To those of the mining industry who would have us believe that mining and manufacturing are totally different enterprises, it can be said that certain differences do exist. These differences rather than being fundamental are the result of adhering to past practices which were possibly sound years ago but do not measure up today. Differences in managerial control, sales, and distribution, cost finding, etc., are often so pronounced that efforts to compare or contrast are almost futile.

Jan 1, 1930

By D. Harrington

One of the main functions of the United States Bureau of Mines is to obtain and disseminate information that will promote safety in and around mines, and the health and safety of employees engaged in mining. Serious health and safety conditions arising out of contamination of air in metal mines by dust, fumes from explosives and fires, and absorption of oxygen by timber and other causes, led the Bureau of Mines to cooperate with the United States Public Health Service in the study of dust occurrence and ventilation in metal mines in various parts of the country. A. J. Lanza, of the U. S. Public Health Service, and Edwin Higgins, mining engineer of the U. S. Bureau of Mines, in 1915, made a detailed study in the mines around Joplin, Mo.; their reports1 are now available. In 1916, 1917, and 1918, a similar study was made in the Butte, Mont., region by Doctor Lanza and D. Harrington, mining engineer of the Bureau of Mines; the reports of this investigation will be available soon. In 1919, the study was continued in some of the Arizona mines by D. Harrington, of the Bureau of Mines, and G. E. McElroy and R. A. Koronski, of the U. S. Public Health Service, the underground work being completed in June, 1920; these reports are now being prepared for publication. In the spring of 1920, the scope of the work was extended, with D. Harrington in charge as supervising mining engineer, and short studies were made in the mines of the Coeur d' Alenes in Idaho and around Oatman, Ariz. It is hoped soon to extend the work into mines of California, Nevada, Colorado, Michigan, and Minnesota, and ultimately to other states should the mining companies be willing to coöperate. While the coöperation of the mining companies is necessary, the companies are put to practically no expense other than supplying a guide to accompany the investigators underground, the length of time spent

Jan 1, 1922

By Eugene Guccione

FOREWORD-At the SME-AIME meeting in Las Vegas this year, the SME Publications Board and the MINING ENGINEERING Committee decided that a fitting way of celebrating the United States' bicentennial would be to publish an article in ME covering the great men in American mining. After some discussion as to the inclusion of financiers -men such as William Randolph Hearst, J. Pierpont Morgan, etc.-the group agreed that the feature should be restricted to the "nuts-and-bolt people," e.g., mining engineers, geologists, mineral processing engineers. Thus, from the AIME All Institute Honors roll and from the SME Awards list, the group chose these 11 historical figures: Herbert Hoover, Daniel C. Jackling, Henry Krumb, James Douglas, Rossiter W. Raymond, Hal W. Hardinge, Seeley W. Mudd, Erskine Ramsay, Howard N. Eavenson, Robert A. Richards, Arthur F. Taggart. What follows is an account of each of these great miners' achievements and the problems they faced, and an assessment by some of today's mining leaders of the challenges that lie ahead.

Jan 7, 1976

By Harry A. Lipsitt, Douglas Y. Wang

A fatigue study in completely reversed axial tension-compression has been perforried on high-purity titanium and on three high-purity alloys of titanium. The alloys each contain approxi7nately 0.75 at. pct of a single interstitial element; carbon, nitrogen, and oxygen, respectivley. The results corroborate a previously published theory which proposed that strain aging under alternating stress was responsible for the fatigue limit behavior of certain alloys. The present data indicate that in these alloys an increasing strain-talline aging effect under alternating stress is provided by oxygen, carbon, and nitrogen, respectively. CURRENT research on the nature of the fatigue limit in metals suggests that the presence of a fatigue limit in metallic materials is a manifestation of strain aging that occurs under alternating stress.lm5 A comprehensive theoretical model based on the above hypothesis has been developed to explain the existence of a fatigue limit.' This model also provides increased insight into several other fatigue phenomena as under stressing, overstressing, and coaxing effects. The theory, as well, provides equal understanding for those cases where no real fatigue limit is observed. Briefly, this theory assumes that the S-N curve for a pure metal is a smooth function of the applied stress, and the effect of adding an element that is soluble (or forms a precipitate) in the pure metal is simply to shift the S-N curve to the right. If the added element confers the power to strain age, the result is a further shift of the S-N curve, this time upward and to the right. Since strain aging is not expected to be a strong function of stress, and since damage per cycle is known to be quite stress dependent, it is to be expected that there will be some limiting lower stress at which the strengthening due to strain aging will balance the damage due to crack propagation. This stress is the fatigue limit. The position of the fatigue-limit knee was thought to be a function of the magnitude of the strain-aging effect on both the finite and infinite life portions of the S-N curve. Although the strain aging hypothesis seems to be reasonably valid for bcc materials,2'6 it needed to be tested for both fcc and cph metals. This report is the first of a series concerning the fatigue-limit behavior of titanium with varying amounts of the interstitial solutes (C, N,, and 4) that are known to cause static strain aging in titanium. Yield-point effects have been reported for polycrys-talline high-purity titanium alloys containing either carbon, nitrogen, or oxygen.7'9 These effects were observed at testing temperatures in the range 100 to 300'. In addition yield-point and strain-aging effects have been reported for single crystals of titanium containing 0.1 wt pct C plus N.' These yield points were observed over a wide temperature range, but no room-temperature aging occurred. Aging at 180' was required to cause the return of the yield point. The magnitude of the yield phenomena in titanium containing interstitials is not expected to be as large as is observed in bcc metals because of several factors. Titanium has a very high chemical affinity for oxygen and nitrogen. The thermodynamic stability of solutions of oxygen or nitrogen in titanium is recognized. Lattice parameter measurements of titanium containing arbon, oxygen,1° or nitrogen" show that the "c" parameter is expanded more than the "a" parameter, but that up to about 2 wt pct this results in an insignificant change of the axial ratio 'c/a." Ehrlich" has shown that the sites occupied by interstitial atoms in titanium are spherically symmetrical and therefore a lattice expansion, at a constant c/a ratio, results in a simple dilation of the interstitial site. Such a dilation involving no shear has been shown to react only with edge components of dislocations.13 This causes only a weak pinning action. Shear stresses would be anticipated locally when only one of the two interstitial positions was occupied. The carbon atom will cause a symmetrical distortion of the lattice whereas the oxygen and nitrogen atoms have, in addition, the previously mentioned chemical affinity of titanium for these elements. These factors will result in a considerably smaller reduction of free energy upon the association of interstitial atoms with dislocations, and therefore a much weaker pinning than has been observed for the bcc metals. These considerations would lead to the hypothesis that of the interstitial elements considered here carbon would cause the strongest pinning effect in titanium where the amount of interstitial in solution is constant. This hypothesis will be borne out in the analysis of the present results.

Jan 1, 1962

By W. R. Ingalls

In reviewing the history of the metallurgy of zinc, I shall pass hastily over what is only of antiquarian interest. That has been excellently treated by Dr. Bernhard Neumann in "Die Metalle" (1904) and has been described briefly in my "Production and Properties of Zinc" (1902), in my "Lead and Zinc in the United States " (1908), and in other metallurgical works of more or less the same date. In this present monograph, I have it in mind to confine myself mainly to technical practice, especially to that of the last 75 years, prior to which period advance was slow and of no great moment. The ancients made brass by the cementation process, i.e., embedding copper in a mixture of calamine and carbon and heating, whereby zinc oxide was reduced and zinc was vaporized and combined with the copper. Zinc was isolated by some of the alchemists, who named it and knew something of its properties, but made no use of it. Long before then, however, zinc was produced in India. Later it was produced in southern China. Possibly the Chinese obtained their knowledge from India. The Chinese in remote places still produce small quantities of zinc. I have seen photographs of their furnaces; or pots, for they hardly deserve the dignity of being called furnaces. I imagine that they are the same that were used centuries ago, for I cannot conceive of anything more primitive. Anyway, it is certain that the idea of a commercial production of zinc in Europe was imported from the Orient, where the metal was known in commerce as Speauter and Spiauter, whence speltrum and finally our term spelter. Tutanego and Tuteneague are other old names. Dr. Isaac Lawson went to China about 1730, expressly to discover the method of its production. What connection there was between Isaac Lawson and John Champion we do not know, but the latter obtained in 1739 a patent for a process of distillation downward and at some time between 1740 and 1743 erected a works at Bristol and actually began the manufacture of spelter. A production of 200 tons per annum is mentioned. In about the year 1766, Rishop Watson visited the Champion works and saw the process in operation, which previously had been

Jan 1, 1937

By Robert H. Richards

The group of four papers on ore dreseing read at the Butte meeting, all of them dealing with the recent developments at the Great Falls and Washoe plants of the Anaconda Company, form an extremely important contribution to the subject of ore dressing. It proves the efficacy of the new hindered-settling principles first brought out in a paper entitled Close Sizing Before digging' and later elaborated in a paper entitled Development of Hindered-Settling Apparatus: and it is the first large demonstration on this class of mill that has been made. It must be very gratifying to all mill men to have these papers at hand, charged with careful investigations and results pointing to the conclusions reached; the papers cannot fail to be a great help to every designer of mills and to mill men who are working on this class of concentration. The papers have dealt with their subjects so completely and have demonstrated every point from beginning to end in each case so thoroughly it leaves little for the commentator to say in the way of criticism. Therefore it seems best to him to confine himself to adding a few points of history which he believes will be interesting to the readers. Referring to the paper by Mr. Wiggin, and to the fact that the Richards hindered-settling pulsator classifier was turned down, the writer wishes to say that this classifier was the first of its kind that had ever been introduced, and since that time it has undergone great developments which he believes would overcome the difficulties encountered in the test,. In fact, there was one test made at Great Falls which with the Wilfley tables and vanners brought all the tailings down to 0.36 per cent. copper except the fine slime. Since that time, and since the classifier has been further developed, in one Colorado mill it proved a wonderful amalgam catcher, catching in all

Jan 1, 1914

By HAROLD A. KNIGHT

The Miami Copper Co., Arizona, is asking Congress to reimpose the import duty of two cents per pound on copper which, by law, has been suspended until June 30, 1950. C. Donald Dallas, chairman of Revere Copper and Brass, champion of a duty-free regime as regards the red metal, has been answering E. H. Westlake, Miami president, now that Mr. Westlake's statement to stock- holders has been salted away for posterity on wire recorders. Even prior to this action and at the instigation of two prominent consumers of pig lead, the House of Representatives has, in the confines of committee, not yet reported out, as of June 16, a bill to suspend the duty on lead for another year from expiration of the present law June 30, 1949. But apparently the bill was started too late. Thus the tariff issue becomes a Rip Van Winkle again after having slept for several years in the mountains of metals scarcity. During the wartime scarcity and the boom days that followed, most metal producers welcomed a considerable influx of foreign metal since it gave them a little surcease from constant teleibhone calls asking why that delivery of 300 tons of lead, 250 tons of zinc, and 1000 tons of copper had been delayed. These were the days when it was such an undisputed sellers' market that the sellers had even thrown away their certificates of ownership. Another development that brings home the tariff situation, small in it- self but perhaps indicating a trend, has been the announced closing of

Jan 1, 1949

By G. Krauss, W. Pitsch

The fine structure of the bcc martensite formed in an Fe-33 wt pct ATi single crystal of arrstenite is sho~on by transmission electron microscoPy to consist of combinations of transformation twins, stacking faults, deformation twins, and regular arrays of parallel screw dislocations. These structures constitute evidence for the multiple lattice-invariant deformations which operating during the formation of martensite could produce the real habit-plane scatter measured by a two-surface analysis of the plates formed in the single crystal of this investigation and reported in the literature for other Fe-Ni rnartensites. CRYSTALLOGRAPHIC theories1,2 of martensitic transformation show that the habit plane of martensite in a parent lattice is dependent in part upon an inhomogeneous distortion or lattice-invariant deformation which takes place on a fine scale within a martensite plate during its formation. Several recent theoretical papers3,4 have addressed themselves to an analysis of a wide variety of conceivable lat-tice-invarient deformations and the habit planes which they produce, while experimental investigation have been concerned with either the measurement of habit planes or the description and identification of the martensitic fine structure which reflects the nature of the lattice-invariant deformation operating during transformation. In Fe-Ni alloys with subzero Ms temperatures, the group of alloys with which this paper concerns itself, habit planes have often been found to scatter an amount greater than might be expected from possible experimental errors,5-7 and fine twinning has been identified as a major constituent of the fine structure of martensite.8-11 It has been suggested3,4 that more than one type of invariant shear occurs during martensitic transformation. This possibility has been experimentally supported12,13 by the observation of both dislocation configurations and twinning in a single martensite plate. The purpose of this paper is to report additional evidence for multiple lattice-invariant deformations in martensite and so to account for the real scatter in the habit planes of the martensite plates formed in Fe-Ni alloys. EXPERIMENTAL PROCEDURE The Fe-Ni single crystal was produced by pulling a high-purity iron and nickel charge through a single-crystal vacuum furnace in an alumina crucible. The crystal was double-melted to promote homogeneity and to increase its size by further additions on the second pass. In its final form the crystal was 4 cm in diam and 5 cm long. The nickel and carbon contents were analyzed at 32.9 and 0.006 wt pct, respectively. The austenite of this alloy first transformed to martensite by bursts at about -120°C, and, to preserve as much of the austenite as possible, all transformation was performed just below -120°C. Some observations were made on transformed samples which had been heated for 2 min at 340°C. It is assumed that the features of the martensite of these samples, Figs. 1 and 4, are the same as those of the as-quenched martensite. Orientation of the crystal by X-ray diffraction established 10.735 0.609 0.3161? as the axis of the crystal, an orientation that was checked within 2 deg by neutron diffraction. Further checks by electron diffraction of samples cut normal to the axis confirmed this orientation within the larger limits of error inherent in electron diffraction of thin foils. The X-ray orientation was the one used for the two-surface analysis of the martensite habit planes. A two-surface analysis was performed on the quadrant of the single crystal which had been oriented by both X-ray and neutron-diffraction techniques. Photomicrographs at X50 were made on two surfaces along an edge 2 cm long. Fiducial marks and the fact that many of the plates were almost completely surrounded by retained austenite made good matching of individual plates on two surfaces possible. The habit-plane trace on a surface was taken as the best line parallel to the long axis of a plate. A measure of the accuracy afforded by this criterion was provided by a family of very large plates which appeared at intervals along the entire 2 cm length of the edge. The plates all had habit-plane traces within 2 deg of one another. Many of the plates did not show midribs and, therefore, the use of midribs7 to represent habit-plane traces was not feasible in this investigation. The over-all experimental accuracy is estimated to be better than ±2 deg. Samples for transmission examination in a Siemens Elmiskop I at 100 kv were prepared by cutting 2-mm-thick discs from the single crystal, removing about 0.5 mm by chemical polishing,14 trans-

Jan 1, 1965

By Milton E. Wadsworth

Hydrometallurgical processing of ore deposits by solution mining or in situ techniques requires the interfacing of technologies as diverse as hydrology, geology, chemistry, and rubblization. This synthesis represents one of the main challenges to in situ processing due to the inherent complexity and vocabulary of these well-developed technologies, and to the general lack of appreciation for the depth of knowledge and endeavor in each separate field. No better example of the need for such interfacing of technologies exists than that of solution mining. How well these technologies interface depends upon the size of the operation and its financial capability to use the information and technology available. It is inconceivable that any one individual can optimize each potential contribution alone; consequently, some areas are usually neglected or simply are not fully appreciated. When one examines what must be done at a future date to develop and exploit a remote solution mining system, it becomes obvious that each discipline must effectively communicate the needed background information to make the project a synthesized whole.

Jan 12, 1977

By A. Alonso, J. Daubenspeck

In the nickel extraction process at Nicaro, Cuba, dried and ground nickel bearing laterites are reduced at 1300-1400F in multiple-hearth furnaces. Nickel is leached from the reduced ore by aeration in an aqueous solution of ammonium carbonate. Nickel carbonate is precipitated from the liquor and calcined to yield nickel oxide. The following are the more important modifications of the Nicaro process since plant rehabilitation and expansion. Ten percent increase in tonnage was achieved without decreasing the fineness of the ore by minor mechanical modifications of the grinding plant. Another five percent increase in tonnage was attained by intentionally overloading the ore prepration and leaching circuits in an effort to control cobalt extraction. Modifications at the sintering plant allowed it to handle the entire output of the expanded plant. A fifty percent increase in leach liquor cooling facilities alone provided an increase in nickel production of five percent. Stronger fresh leach liquor for increased nickel washing efficiency was obtained through improved distribution of water to the ammonia absorption towers. Advantage was taken of the reduced calcine's capability to precipitate cobalt, and modifications in the leach liquor circulation provided controlled cobalt solubility with minimum harm to nickel extraction. Several process changes at the drying plant brought about a ten percent reduction in the fuel oil consumption at this pint. Controlled air addition to the reduction furnaces' upper hearths burned formerly wasted combustibles thereby reducing oil consumption by twenty percent. The nickel extraction process successfully emplayed on the extensive but lowgrade lateritic ores of Eastern Cuba at the U. S. Government owned Nicaro plant, has been previously described in various publications. The large mine and plant operated by the Nickel Processing Corporation, located on the northeastern shore of Oriente Province, have been recently expanded to a yearly capacity of about 50 million pounds of nickel. Essentially, the operation involves open pit mining of a limonite-serpentine ore mixture containing 1.3 to 1.4 percent nickel and 34 to 38 percent iron. The comparatively lumpy, wet (25 to 30 percent moisture) ore is first dried and ground prior to chemical treatment, to which the entire 7,000 tons per day feed must be subjected. In the initial chemical action the dried and ground ore is reduced with carbon manoxide and hydrogen at 1300-1400° in multiple-hearth furnaces. The resulting metallic nickel is selectively leached from the reduced calcine by aeration in an

Jan 1, 1961

By T. Egleston

AT the Dover meeting of the Institute, Mr. F. A. Canfield showed some of the members a machine which he had invented for dressing mineralogical and geological specimens, which he has since modified and brought to such a high state of perfection, that after having used it for several months in preparing specimens for the cabinet of the

Jan 1, 1876

By T. Egleston

At the Dover meeting of the Institute, Mr. F. A. Canfield showed some of the members a machine which he had invented for dressing mineralogical and geological specimens, which he has since modified and brought to such a high state of perfection, that after having used it for several months in preparing specimens for the cabinet of the