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By J. A. Scott, F. R. Hensel

The paper deals with the investigation of two types of coreless induction furnaces, one of 60 cycles, the other of 5000 cycles. Nickel was used as test material and the absorption of oxygen by molten nickel was chosen for determining the influence of the frequency on the metallurgical characteristics of the furnaces. Dr. Herty's aluminum method, slightly modified, was found suitable for determining the nickel oxide content in nickel. Also an electrolytic method for determining alumina in nickel was worked out. The solubility-temperature relations for nickel oxide in molten nickel were determined approximately. It was found that the solubility of nickel oxide increases with the temperature. Comparative tests on the rate of oxygen absorption made in a 60 and a 5000-cycle furnace showed that the absorption of nickel oxide in nickel is an increasing function of turbulence, time and temperature. The rate of oxygen pickup in the 60-cycle furnace is about three times as great as in the 5000-cycle furnace. In the 60-cycle furnace the maximum oxygen content of the melt comes close to the saturation limit. Melting under an oxygen-free atmosphere prevents oxidation in both types of furnaces. DISCUSSION (Iloward Scott presiding) H. Scott, East Pittsburgh, Pa.—When Professor Desch was in Pittsburgh recently he mentioned that the induction furnace has practically replaced the crucible furnace in Sheffield except for the carbon tool steels. Dr. Hensel is to be congratulated on the development of analytical methods for determining inclusions and for getting two different methods to agree. F. R. Hesnsel—Recently the purification of molten metals with hydrogen or other suitable gases has become an important issue and a number of patents have been taken out covering gaseous treatments of molten metals. In this connection I wish to call

Jan 1, 1933

By R. A. L. Black

Rock mechanics is a very new science. It has been accepted as a recognized discipline for some two decades, but it is only within the last five to ten years that it has been common to include the teaching of rock mechanics as a separate subject in undergraduate curricula at universities. Thus, few senior mining engineers practicing in industry, either men in charge of production or those engaged in mine planning and design, are familiar with the subject. That this unfamiliarity has continued so long is also due in part to the fact that the results of rock mechanics investigations have been published in a large number of different periodicals covering subjects ranging from experimental stress analysis to obscure branches of applied earth sciences. The first really useful textbook ' in the English language was published only in 1965, in Canada. It made available to students and to practicing engineers, for the first time in concise form, the essential body of accepted knowledge about rock mechanics and developed the theories on which it is based in a simple, clear and logical manner. Another factor which has resulted in rock mechanics science being slow to be accepted by the mining industry is that research work has often appeared to be esoteric and unpractical. Senior engineers have been reluctant to spend money on the application of new knowledge when the process of application seemed uncertain and ill-defined, and where the cost of field investigations (which is necessarily high) appeared to offer no certainty of economic reward. This is a reasonable attitude on the part of mining engineers; they are responsible to skeptical boards of directors whose chief concern is, very properly, the net return on capital invested. The application of rock mechanics science has not in the past,

Jan 1, 1968

By Sherwin Kelly

The prime objective of geophysical exploration is to promote the economical and rapid dis-covery of mineral or oil deposits of commercial value. To a few this concept as applied in min-ing may signify the direct discovery of ore-bodies, but to the geophysical engineer this latter Idea is one of the most insidious and detrimental misapprehensions which he has to combat. The destruction of this annoying obstacle to the progress of geophysical exploration reveals the kernel of truth behind it, that the exploration geophysicist has for the better part of two decades been concerned primarily with the discovery of mineral formations favorable to the occur-rence of commercial ore. There is a very real distinction here, since geophysical methods are capable of discovering certain mineral formations such as sulphide bodies or quartz veins, but are totally incompetent to predict whether or not they constitute ore; that is. whether or not they contain minerals of economic value in the amounts requisite to repay extraction. The art of geophysical exploration is now, however, rapidly outgrowing these early limita-tions. The rate of this growth will in large measure depend on the recognition by the mining industry of the fact that geophysics can play a role far wider and more important than it usual-ly does now, in guiding the future exploration and development of mineral deposits. It is my own firm conviction that as time marches on we will see the methods of applied geophysics turned more and more to the delineation of both minor and major structural features. The outlining of such features having a bearing on the probable loci of mineral deposition will be of inestimable value in guiding the development of a mining district. It is in this field that there will In-evitably occur a meeting and overlapping of the activities of the exploration geophysicists and

Jan 1, 1940

By T. B. Counselman

THE importance of concentration of iron ores too low in grade to be smelted direct is shown by Table I, showing 1940 ship- [ ] ments from the Lake Superior district. Canadian ores are omitted. [ ] Only in Minnesota is concentrating, other than crushing and screening, practiced at present. Tonnage produced by various methods of concentration is shown in Table 2. The curves in Fig. I show the gradual increase in tonnage of concentrated ores shipped, compared with total shipments from Minnesota. Most of the concentration work is performed on the Mesabi Range. This range is about 100 miles long, and not over 3 miles wide from the line at which the formation tapers out to a feather edge on the north to the place on the south at which, some 600 ft. thick, it is overlain with slates. CLASSES OF ORE The Mesabi Range contains three classes of iron ore. First is the unaltered taconite, or banded iron-bearing chert. It is estimated that there are some 60 billion tons of this material, which contains, roughly, 25 to 30 per cent iron. This material is virtually untouched, since no commercially successful method has yet been found for concentrating it to a grade suitable for the blast furnace. Intensive experimental work is in progress, and the problem is gradually being solved. In 1922 the Mesabi Iron Co. spent several million dollars erecting a large-scale pilot plant for concentrating and sintering the magnetic taconites on the east end of the range. An important tonnage of high-grade sinter was shipped to lower lake furnaces, proving that the taconite can be concentrated to a satisfactory grade. The costs, with equipment and methods then in use, were too high for

Jan 1, 1941

By Richard P. Rothwell

IN the pear 1881, I visited San Domingo, in the interest of French capitalists, to examine and report upon certain "concessions" of gold-bearing gravel and quartz veins, on the Isabella and Jaina rivers and their tributaries. This district is periodically reported to he extraordinarily rich, and there is oast around it the glamour of the mysterious shipments of gold, credited, in romance and in more or less romantic history, to Columbus and the Spaniards of the fifteenth and sixteenth centuries. Since considerable sums of money and several valuable lives have been lost in the unsuccessful search for its profitable mines, it seems desirable to place on record Borne of the information collected concerning the value of these famous gold fields, with the hope of facilitating the work of those who may hereafter be called on to investigate these claims, and of preventing the unnecessary waste of capital. It is needless to add that the capitalists for whom my investigations were made abandoned the enterprise they had in view,although no doubt similar schemes will be brought forward many times in the future, as they have been in the past, under the fervent advocacy of too sanguine enthusiasts. Since the time of the Spanish occupation of the Island of San Domingo, in 1497, when Columbus Found the natives wearing ornaments of gold, more or less of the precious metal has been obtained annually by washing the gold-bearing sands of several of its streams. It is said that during the Spanish domination, when the native Indians were held in the most abject servitude, a certain amount of gold was required of each one as the rault of his labor. Uuder this

Jan 1, 1882

By C. T. Eddy

The refining of native copper in the reverberatory furnace, as practiced in the Lake Superior district of Michigan, is very similar to the reverberatory melting and refining of cathodes, but the presence of arsenic in some of the copper concentrates renders the operation somewhat more difficult. Though the copper occurs as the native metal, which is often excep tionally pure—purer, in fact, than after it has undergone refining—its intimate association with the gangue minerals necessitates the cumbersome reverberatory treatment. The gangue consists chiefly of complex silicates of calcium, magnesium, iron, aluminum and sodium, but in certain ore deposits other minerals are often found, among them the native copper arsenides—mohawkite, whitneyite, algodonite and the like. These latter minerals, when present, because of their relatively high specific gravity (7.5 to 8.5), find their way into the concentrates through the gravity concentration processes employed in the recovery of the copper. When such concentrates are melted, the silicates are removed as slag, but, because of the great affinity of molten copper for arsenic, the arsenides dissolve more or less completely in the copper bath. Because of the stability of the resulting melt, the arsenic is tenaciously held in solution. The influence of arsenic on the properties of copper, especially on its electrical conductivity, is generally recognized. For certain uses it is beneficial, and in many instances its presence in limited amounts is not objectionable, but if the metal is to be used for electrical purposes, the almost complete removal of the arsenic is of prime importance. Considerable research has been done on the subject of the influence of arsenic on the electrical conductivity of copperll but the conclusions presented in the literature dealing with the problem show some disagreement. The methods now in use for the removal of arsenic have not

Jan 1, 1931

By Kenneth B. Barnes, George H. Fancher

With the advent of water-flooding into active commercial usage in half a dozen areas in the Mid-Continent, the process passes the experimental stage and joins other methods and processes now in use which have been found suitable in one oil field or another in securing a more profitable production than has existed heretofore. The use of the air-gas lift, acidization, pressure maintenance and repressuring have presented their problems in economics and engineering during their introduction and extended application. When a new field is discovered or attention is turned to an old producing area in which these methods have not been considered, it is to be expected that these problems again arise. While some information is available as to the results obtained by water-flooding in a few localities in the Mid-Continent, the extrapolation of the sand data on which the results are based, for even generalized use in other areas and fields in the region, is hazardous. It is precarious to assume that the same physical condition will obtain in a sand over more than small, special areas. This paper is concerned with a brief presentation of such data as are available to the authors on existing operations, a survey of the region and extent to which application of the method seems most likely to be made, an estimation of the crude reserve existing for such operations, suggestions as to the importance of core analysis in guarding against uncontrolled floods and its usefulness in predicting ultimate recoveries, and comment on some of the economic phases involved. These subjects, as concerned with water-flooding in the East (notably Bradford, Pennsylvania), have been discussed in detail in the literature and are generally well known. Especially is this true of discussions of the mechanical equipment and various lease layouts and development patterns for water-flooding.

Jan 1, 1936

By Kenneth B. Barnes, George H. Fancher

With the advent of water-flooding into active commercial usage in half a dozen areas in the Mid-Continent, the process passes the experimental stage and joins other methods and processes now in use which have been found suitable in one oil field or another in securing a more profitable production than has existed heretofore. The use of the air-gas lift, acidization, pressure maintenance and repressuring have presented their problems in economics and engineering during their introduction and extended application. When a new field is discovered or attention is turned to an old producing area in which these methods have not been considered, it is to be expected that these problems again arise. While some information is available as to the results obtained by water-flooding in a few localities in the Mid-Continent, the extrapolation of the sand data on which the results are based, for even generalized use in other areas and fields in the region, is hazardous. It is precarious to assume that the same physical condition will obtain in a sand over more than small, special areas. This paper is concerned with a brief presentation of such data as are available to the authors on existing operations, a survey of the region and extent to which application of the method seems most likely to be made, an estimation of the crude reserve existing for such operations, suggestions as to the importance of core analysis in guarding against uncontrolled floods and its usefulness in predicting ultimate recoveries, and comment on some of the economic phases involved. These subjects, as concerned with water-flooding in the East (notably Bradford, Pennsylvania), have been discussed in detail in the literature and are generally well known. Especially is this true of discussions of the mechanical equipment and various lease layouts and development patterns for water-flooding.

Jan 1, 1936

By Fred A. Anderson, George B. Wallace, Edward J. Slebir

Auburn Dam will be a thin, double-curvature concrete arch dam about 685 ft high. With a crest length of about 4000 ft, it will be the world's longest single-arch dam. The site is located on the North Fork of the American River about 40 miles northeast of Sacramento, Calif. Construction is scheduled to get under way in 1970. In planning for the design and construction of Auburn Dam (see artist's conception), the foundation material, with its various discontinuities, is being investigated and the structural characteristics of the rock mass evaluated. The investigation and testing programs will aid in defining the pertinent geologic features and their individual and cumulative influence on the foundation. The work includes geologic surface mapping, surface trenching, core drilling, geophysics, tunneling, excavating shafts and raises, performing in-situ tests, and conducting laboratory tests on core and block samples. Competent amphibolite is the predominant material in the foundation, but significant bodies of chloritic, talcose, and metasedimentary rocks, a strongly developed jointing pattern, faults, and shear zones also affect the deformability of the rock mass. A comprehensive rock mechanics program, closely coordinated with geologic investigations as well as the engineering studies, therefore is required The rock mechanics work is a combination of many analytical studies and experimental investigations. The experimental work includes laboratory tests on core samples from holes drilled for geological studies of the entire foundation and in-situ tests performed in selected areas. The laboratory testing program evaluates the general properties of all important rock types and aids in correlating many of the key structural features encountered within the foundation. To derive maximum benefit from the field tests, they are conducted in materials which represent a

Jan 1, 1970

By James C. Ray

The age classification of the mineralized veins of the Butte district, as given by Weed and Sales, was tacitly accepted for many years. Weed, whose field work was completed in 1906, divided the copper veins into groups of four ages.' In 1913, Sales modified Weed's classification and assigned all mineralized veins (including the silver-zinc veins of the border or "peripheral" zones) to three periods of fracturing and mineralization. Both writers based their classifications mainly on the relative ages of the observable faulting whereby the veins of a so-called "earlier" system are intersected and offset by those of a "later" system. Nevertheless they possess structural and mineralogical characteristics in common which indicate that they are of the same age. The writer has maintained since 19143 that these vein systems were formed during one general period of mineralization along a network of intersecting fractures of approximately simultaneous origin and that the existing offsets are largely due to postmineral faulting. Leith,* takes cognizance of the accumulating mass of data relative to the simultaneous formation of intersecting fracture systems and says, referring to ~utte: "It now appears that the mineralization accompanying them (individual structure systems into which the veins have been grouped) is substantially of one period, indicating that the successive structural movements took place mainly within the period of mineralization." This paper presents the results of certain structural experiments which suggest a modified interpretation of the published data on the Butte district. The interpretation is substantiated by the writer's observations in the Butte mines and is offered with the hope that it will reconcile the structural with the mineralogical conditions existing in this most interesting district; also, that it will emphasize the importance of a

Jan 1, 1931

By Barry K. McMahon

The fundamental problem in rock mechanics is accounting for the discontinuous and anisotropic nature of the jointed rock mass. It is this problem that makes rock mechanics distinct from the mechanics of steel, glass, or concrete. Existing mathematical models explain much of the behavior of rock cores in the laboratory but, in civil engineering at least, the rocks that matter are the ones that are already broken. On the other hand, the basically descriptive methods now used in engineering geology do not lend themselves easily to mathematical analysis. A set of indices of geological properties related to the strength and deformation characteristics of jointed rock is needed. Like the index properties used in soil mechanics these will probably not have precise mathematical meaning, but once correlations are established with large scale tests they can form a basis for the transfer of test results, obtained in one area under one set of conditions, to the prediction of rock behavior in another area under another set of conditions. Indices of rock properties are even more important in rock mechanics than in soil mechanics as the cost of testing is much higher. To be useful, these indices must be easily and quickly measured and give reproducible results when measurements are made by different people. In this paper the word "joint" means all naturally occurring rock fractures with less than 3 in. of clay or other soft coating material. EXISTING INDICES OF ROCK PROPERTIES A comprehensive review of indices of rock properties for intact rock is given by Deere and Miller.' They provide charts ". . . for estimating the strength or modulus properties for intact rock from the numerical indices obtained by either the Schmidt hammer, the Shore Scleroscope,

Jan 1, 1968

By E. C. Harder

The situation in the United States, at the present time, regarding the supply of manganese ores and alloys of manganese is one of great seriousness and is likely to become increasingly so while the European war continues. The two principal iron-manganese alloys, ferromanganese and splegel-eisen, are indispensable in steel manufacture, being used extensively in the Bessemer and open-hearth processes. Spiegeleisen, the lower alloy, contains between 15 and 25 per cent., and ferromanganese, the higher alloy, between 60 and 80 per cent., of manganese. Besides manganese the alloys contain iron and carbon. On the market ferromanganese is usually quoted on the basis of 80 per cent. manganese, and spiegeleisen on the basis of 20 per cent. manganese. The consumption of ferromanganese has been increasing during recent years at the expense of spiegeleisen, because larger quantities of the latter must be used to accomplish the same purpose with the result that the amount of carbon introduced with it into the molten metal is frequently injuriously great. Manganese ore proper, in the form of manganese dioxide, is used extensively in many chemical industries, especially for oxidizing purposes. It is also used for the manufacture of both wet and dry electric cells and in the manufacture of paints and dyes. The manganese ore used in this country has been derived hitherto from three principal sources: Southern Russia, Southern British India and East Central Brazil. The following tables show the quantity of manganese ore imported from these countries, and (for comparison) the domestic production, during 1912, 1913 and 1914. The imported manganese ore has been used largely in the manufacture of iron-manganese alloys and in addition large quantities of the alloys themselves have been imported, chiefly from Great Britain, Germany and other European countries.

Jan 1, 1917

By Otto F. Pfordte

The great advance of the last twenty years in the specialization, delicacy and efficiency of ore-concentrating apparatus calls for a finer system of testing both the qualities of ores and the operations of machines in this department. In amalgamation, lixiviation and smelting, the daily employment of physical and chemical tests has been recognized as necessary, and the cost of the necessary laboratories and employees is cheerfully paid. But while much progress has been made in concentration (due, in a large degree, to the study of the subject in our technical schools), it is still too common in actual practice to follow the loose old method of roughly estimating, once for all, that a given ore " concentrates x tons into one," and resting on this assumption so long as that ore continues to be treated, while assays of the tailings from concentration are made from time to time, without exact determination of their quantity. The first step toward accuracy of control must be a more frequent and precise measurement of the quantity of concentrates from a given operation. This should be expressed in pounds per unit of one ton; and the variations shown in frequent determinations will furnish a constant check upon the character of the ore and the performance of the apparatus. But this is only a part of what should be constantly and systematically done to insure the best work upon a material which must vary continually, even though it come from one mine only. If, in any mill, appropriate laboratory-tests were made at least once a week, the labor and expense involved would be amply repaid by increased knowledge and control of the current operations. A small testing-laboratory, provided with a few gold-pans;

Jan 1, 1902

ROBERT M. KEENEY,* Portsmouth, Ohio (written discussion?).- Mr. Coffin has written a most interesting paper that covers most of the uses to which water-cooled devices are subjected; but to meet with the operating department's approval, these devices must effect a saving in cost per ton of ingots produced in the furnace. The making of steel in the open-hearth furnace is dependent entirely on the personal element. It is not possible to charge the furnace with so much raw material, turn on a valve for heat, and by use of recording thermometers, clocks, etc. empty the furnace when a steel is made. Competent men trained to the work must be in charge all the time, and the quality and quantity of steel produced is quite as dependent on the care and working qualities of the furnaces as on the raw material and working of the charge itself. Steel making is hot, hard work and the inducement offered to technical men to take up this work is not sufficient to induce many to enter the field. The result is that most of the workmen in an open-hearth plant, the men who actually operate the furnace and make the steel, are not technical men and do not understand the "whys" and "wherefores " and care less. All this means that a furnace must be built as nearly fool-proof as possible. By this I mean that it is necessary to protect those parts of a furnace most subject to abuse by water-cooled devices whenever possible, and these water-cooled appliances must he as nearly fool-proof as they can be made. The control of the gas entering a furnace is of the utmost importance. This means a properly designed port must have the same design throughout the whole run of the furnace. This is not possible with the ordinary

Jan 6, 1919

By David Browne

THE use of coal-dust fired reverberatory furnaces, or indeed of reverberatory furnaces of any description, was for the Canadian Copper Co. a matter of necessity, and not of choice. For 20 years smelting had been done in blast furnaces alone, and with the Herreshoff furnaces used prior to 1904 there was no trouble in treating fine ores. But little flue dust was produced, and this, following the time-honored custom, was wetted down and put back with the charge. Whether the flue dust really smelted, or whether it was worn out by being chased around in a circle, was a problem that troubled no one. With the installation of modern blast furnaces and high-pressure blowing engines, in 1904, flue dust commenced to assert itself. Evidently more dust was made than could be smelted, but so many vital problems engaged our attention at that time that this minor question was pushed to one side. In 1906, the details of blast-furnace smelting and the conversion of matte had been worked out to a satisfactory conclusion, and the ever-increasing piles of flue dust and fine ore on the stock yard demanded serious consideration. Numerous experiments in sintering, briquetting, mixing with converter slag, forming blocks of flue dust with green-ore fines and cement, and so on, were undertaken. None of these showed much promise. Our problem, was still further complicated by the question of treating converter slag. The ore was basic, the slag was not needed as a furnace flux, and it was felt that under these conditions the old method of pouring slag in molds and resmelting in the blast furnace was an unnecessary expense. If the converter slag could be settled in basic-lined reverberatory furnaces, in which at the same time flue dust and green-ore fines could be smelted, two problems might thus be solved.

Jan 1, 1915

By Hewitt Wilson

CHALK is soft, pulverulent limestone formed from calcareous remains of microscopic organisms. Whiting is the powder made by the fine- grinding of limestone. Although European chalk dominated the early American market and is still shipped to the eastern and western seaboards, the domestic producer, by new technical processing, improved equipment, and proper selection and mixing of raw materials has shown that the United States can be independent of foreign sources. DISTRIBUTION European Chalk-Outcrops of Cretaceous chalk are found in the area roughly bounded by Antrim, Ireland, on the east, East Prussia on the west, Sweden and Scotland on the north, and Nice, France, on the south. Commercial chalk is mined from the chalk cliffs between Dover and Hull, England; from deposits near Mons, in the Departments of Pas de Calais and Nord in northern France; and from similar de- posits in Denmark and Belgium. United States-Some grade of limestone is found in every state of the Union, but true chalk of Cretaceous age is limited to three large areas in the central and southern states. Niobrara (Cretaceous) chalk outcrops are found as a narrow band encircling the Black Hills in South Dakota, Wyoming, and Nebraska, and in much larger exposures in southeastern South Dakota, eastern Nebraska, and western Kansas. A third chalk belt extends from west central Arkansas into Oklahoma and connects with the Austin beds, which almost cross Texas. In the southeastern states, the Selma chalk extends from western Tennessee south through northern Mississippi and turns east across central Alabama. Most of the domestic chalks are discolored with iron oxide or carbon. Some marls can be included with chalks of commercial possibilities. Some of the soft, cream-colored limestones of northern Florida, Georgia,

Jan 1, 1949

By W. A. Mudge, Paul D. Merica

One of the most prominent features of our present-day industrial development is the ever-increasing demand put upon materials of construction. Engineering ingenuity, within the past 25 years, has been unusually active, and in some fields at least engineers frankly say that engineering design has progressed as far as the limitations imposed by the properties of the present materials of construction will permit. Consequently, they are today demanding improvement in their working materials and seeking new ones, through the aid of which the present limitations of design may be overcome. The activity of this search is evident in all fields, but it is particularly so in that of structural materials required to be resistant to corrosion. The corrosion resistance of metals and alloys is never absolute and all-inclusive; a particular alloy will withstand some corrosive conditions well and fail utterly under others. Furthermore, other properties, physical and mechanical, required in conjunction with corrosion resistance vary considerably for different commercial applications. One wants a soft, ductile sheet metal resistant to atmospheric corrosion; another, a high-strength alloy resistant to sulfuric acid. The last decade has witnessed active and definite progress in the development of high-strength, corrosion-resisting alloys. In June, 1924, a symposium by the American Society for Testing Materials, on Corrosion-resistant, Heat-resistant and Electrical-resistance Alloys, disclosed no less than 60 commercial alloys the properties of which were described as being suitable for industrial service where corrosion resistance was a feature. Today the number of these alloys has been doubled, at least. In addition, economy in design and construction through decreased weight has given considerable impetus to the improvement of alloys of which the mechanical propprties may be improved by heat-treatment.

Jan 1, 1935

By Paul D. Merica, W. A. Mudge

One of the most prominent features of our present-day industrial development is the ever-increasing demand put upon materials of construction. Engineering ingenuity, within the past 25 years, has been unusually active, and in some fields at least engineers frankly say that engineering design has progressed as far as the limitations imposed by the properties of the present materials of construction will permit. Consequently, they are today demanding improvement in their working materials and seeking new ones, through the aid of which the present limitations of design may be overcome. The activity of this search is evident in all fields, but it is particularly so in that of structural materials required to be resistant to corrosion. The corrosion resistance of metals and alloys is never absolute and all-inclusive; a particular alloy will withstand some corrosive conditions well and fail utterly under others. Furthermore, other properties, physical and mechanical, required in conjunction with corrosion resistance vary considerably for different commercial applications. One wants a soft, ductile sheet metal resistant to atmospheric corrosion; another, a high-strength alloy resistant to sulfuric acid. The last decade has witnessed active and definite progress in the development of high-strength, corrosion-resisting alloys. In June, 1924, a symposium by the American Society for Testing Materials, on Corrosion-resistant, Heat-resistant and Electrical-resistance Alloys, disclosed no less than 60 commercial alloys the properties of which were described as being suitable for industrial service where corrosion resistance was a feature. Today the number of these alloys has been doubled, at least. In addition, economy in design and construction through decreased weight has given considerable impetus to the improvement of alloys of which the mechanical propprties may be improved by heat-treatment.

Jan 1, 1935

By Robert Anderson

DURING the past 5 years no subject has aroused more interest or received more attention among mill operators than flotation. One reason for this is, undoubtedly, the remarkable success of the process in Australia where that country has risen to the position of furnishing one-fifth of the world's Supply of zinc. The plant of the Butte & Superior Copper Co., designed by James M. Hyde in 1912, was the first important large flotation plant in this country; other installations have been made since then with considerable frequency, particularly so in the last 2 years. Without going into complete detail, it may be safely said that although flotation is a highly successful commercial process, it is more or less on an empirical basis. Upon scanning the literature, it is found that the flotation investigations have, in the main, dealt with a solution of the problems which accrue to practise; until recently no attempt was made to remove the difficulties in the way of the formulation of a consistent and harmonious theory. Of late this phase of the work has been receiving considerable attention, particularly by the United States Bureau of Mines at its Salt Lake City station, by the Mellon Institute at Pittsburgh, by the General Engineering Co. at Salt Lake City, by many of the mining schools, and private individuals almost ad infinitum. There is, at present, an enormous amount of laboratory work being carried on in flotation research, and probably the time is not far away when a generally acceptable explanation of flotation phenomena can be Set forth. However, at this time, it seems as though the current technology is befogged with a super-abundance of contradictory evidence; this confusion can only be dispelled as time proceeds and the knowledge of the subject becomes more complete.

Jan 7, 1916

By Theodore Simons

Permission to present this paper at the February, 1915, meeting of the Montana Section of the American Institute of Mining Engineers was liberally granted by W. A. Clark, Jr., President-and General Manager of the Timber Butte Milling Co., and by the representative of the Minerals Separation Co. For the many courtesies shown the writer on his visits to the mill and for information supplied, he is indebted to all the officers of these companies, especially to W. N. Rossberg, W. D. Mangam, Hamilton Cooke, Jr., T. M. Owen, T. C. Wilson, R. McGillivary, L. L. Quigley, C. Bartzen and others. The writer takes this opportunity to herewith express to them his appreciation and sincere thanks. Location of Mine and Mill The concentrator of the Timber Butte Milling Co. was built to treat the ore mined at the Elm Orlu mine of the Elm Orlu Mining Co., which carries zinc and lead in sphalerite and galena; copper in bornite, chal-cocite, tennantite, and tetrahedrite; and gold and silver either free or chemically combined with the sulphides of the base metals. The gangue is chiefly quartz, barite, fluorite, rhodonite, and rhodocrosite. The iron in the ore occurs as irqn pyrites. The Elm Orlu mine is situated in Butte, Silver Bow County, Mont., near the northern border of what is locally known as the Butte sulphide-copper belt, about one mile north of the Anaconda mine, and adjoining the Black Rock zinc mine of the Butte & Superior Co. on the southwest. The mill is on the northern slope of Timber Butte, a prominent topographical landmark in the Butte district. This site permits to a large extent the gravity system of ore flow; it presents a convenient and extensive area for a tailings pond; and it is comparatively near to the source of water supply and to existing railroads.

Jan 1, 1916