Search Documents

By Granville S. Borden

THE program for income tax legislation presented here proposes some diminution in the current tax burden on mineral producers but it will, if enacted, eventually increase the potential and current Government revenue from the mineral industry.

Jan 6, 1951

Plans for the fall meeting of the AIME, to be held in conjunction with the Centennial of Engineering -marking the 100th anniversary of the Society of Civil Engineers-indicate that the Chicago gathering will be one of the most significant in Institute history. Headquarters for the six divisions represented will be the Palmer House. Twenty technical sessions will be held from September 3 to 6, with papers of industry-wide impact to be presented. The papers will follow the theme of the celebration-a century of engineering progress. The MBD will start the ball rolling with morning and afternoon sessions Thursday, September 4. A luncheon also will be held. MBD has scheduled morning and afternoon sessions for the following day as well. MGGD, Iron and Steel, and the Coal Div., will hold sessions Friday afternoon. The Industrial Minerals Div. plans an executive meeting, 5 pm, Friday. Geology Subdivision is slated for morning and afternoon sessions Saturday. The Coal Div. will meet again Saturday morning.

Jan 1, 1952

By Y. Takahashi, I. Iwasaki, S. Tanabe

Supported by the vigorous capital investment of the heavy and chemical industries and by the ever-increasing demand for durable consumer goods in the past decade, Japan has now emerged as the world's third largest steel producer, surpassed only by the United States and the Soviet Union. In 1968, the crude steel production is expected to exceed 50 million tons; the per capita steel consumption at that time will reach 886 lb, approaching the level of Western Europe. Characteristics of the Japanese steel industry is the high dependence of raw materials on overseas sources. Before World War II the industry relied on North China and Manchuria for coking coal, and on middle China, Hainan Island, the Philippines and the Malayan Peninsula for iron ores. After the war, the major sources of iron ores were shifted to the Philippines and the Malayan Peninsula, supplemented by shipments from the United States, Canada, India and Goa. The United States, in addition, became the primary source of coking coal.

Jan 1, 1967

By Bernard York, John J. Reed

Mine opening stability was investigated by loading model openings to failure. Eight-inch plaster blocks were cast with small uniform section openings passing through the centers. After curing, the models were jacketed and loaded hydrostatically in a closed vessel. Opening size, shape, and orientation were varied to determine how these factors influence opening stability. THE investigation described in this paper is a continuation of a project begun in 1946 by Bernard York and W. E. Bush. .The experimental method used in the investigation involves the hydrostatic loading of a model mine opening to failure. Most investigators agree that this loading closely approaches actual conditions in very deep mines. The conditions are further idealized by using an essentially isotropic model material. The experiments consist of casting 8-in. plaster cubes, or 8-in. diam cylinders 8-in. long, having a relatively small uniform section hole passing through their centers. After thorough drying, the models are jacketed in a flexible plastic bag and loaded hydrostatically with water in a closed vessel. At about 300 to 500 lb per sq in. pressure the central opening fails. The fracture pattern resulting from opening failure is studied in a plane normal to the longitudinal axis of the opening. The model block is sawed through its center after loading to expose this plane and to eliminate the possibility of end effect. By changing

Jan 1, 1954

During the year Jan. 1 to Dec. 31, 1916, 962 applications for member-ship in the Institute were received, as compared to 558 during the corresponding period in 1915. The lines along which the Committee has, worked during the year, group themselves under seven principal heads. Large Companies.-Early in the year a letter was addressed to each member of the Institute who is the executive head of an organization, pointing out to him the advantages that would accrue to that organization through having as many of its subordinate members as were qualified participating in the activities of the Institute. This was followed by a second letter to those who made no reply to the first. The response to these letters was very gratifying, 12 new members having been secured at a single plant, and smaller numbers at others. This was effectively supplemented by our President, who wrote the executive heads of some of the largest mining and smelting companies, pointing out to them the advantage to be derived from sending some of the junior members of their staff to attend the Arizona Meeting. One organization sent 24 of its younger men, many of whom were not members of the Institute, but who, subsequently sent in applications for membership. It is to be hoped that the precedent thus set' will be acted 'on in -fuller measure in succeeding years.

Jan 2, 1917

By Richard L. Gordon

Minerals long have been important commodities in international trade. As an inevitable result, the governments of the world have employed a wide variety of programs that affect the flow of trade. Roughly speaking, we may distinguish between the desire of more developed countries (MDCs) like the United States, western Europe, and Japan to control imports of minerals and the concern of less developed countries (LDCs), like India, about exploiting and exporting their minerals. The terminology used to describe different countries and the classification of specific countries into groups is unsettled and often changing. The poorest countries have been characterized as backward, undeveloped, underdeveloped, and developing. The problem seems to be in selecting a term that is both accurate and polite. Less developed seems, for reasons outlined by Hagen [pp. 51-57], the most convenient term. The borderline between an LDC and an MDC is always open to dispute. Objective measures are difficult to develop because of deficiencies in basic data, and enormous conceptual problems arise in making valid comparisons from even good data [see Hagen, pp. 7-28]. Thus, policies of the MDCs can be evaluated chiefly by using a few basic arguments for protectionist attitudes towards international trade. In dealing with the LDCs, a more far-ranging evaluation that covers general economic policy goals, the role of foreign investment, and the indirect effects of trade is required. This duality breaks down when trying to deal with the depressed areas in an MDC; here the issues are more akin to those associated with problems in an LDC. Similarly, variants of arguments used in LDCs appear in debates about foreign investments in MDCs. The whole discussion of minerals in LDCs, moreover, has obvious implications for MDCs like Canada and Australia. They, too, must face problems about the best utilization of their resources. THE RESTRICTION OF MINERAL TRADE BY DEVELOPED COUNTRIES[a] At least to some extent, the world's leading industrial nations have intervened to control the inflow of minerals. Such regulation is particularly pronounced for energy. Both the United States and western Europe employ

Jan 1, 1976

THE composition and quality of finished steel depend upon selection and proportioning of the raw materials of the charge as well as on control of furnace practice. This chapter deals only with those raw materials of the basic open-hearth process which are important in determining the composition of the steel or slag. They are the metallic charge, oxygen-bearing materials, fluxes, and alloying and deoxidizing additions. Refractories, which may also affect the slag composition, are discussed in the previous chapter. Wide variations are possible in the type and composition of charged materials, but in all cases certain fundamental relationships among the elements of the charge must be maintained. Since the process consists essentially of refinement by oxidation of undesired elements, a balance must be established between the sources of oxygen and the elements in the charge that are subject to oxidation (see Chapters II and VII). For example, if it is desired to use a high ratio of blast-furnace hot metal to scrap, it is necessary to add an oxygen-bearing material such as ore or mill scale to eliminate the excess carbon and silicon that are present in the hot metal. An example of the opposite extreme would be the use of a metallic charge composed entirely of steel scrap. With this type of charge, it is common practice to substitute burnt lime for limestone as a flux and to charge some carbonaceous material such as coke to avoid an excess of oxygen in relation to the elements of the charge that are subject to oxidation. Elements such as copper and nickel, which are not subject to oxidation or other reactions resulting in their elimination, may be introduced into the charge only to the extent to which they are permissible in the finished steel. An example of adjustment of the charge for elements of this type would be found in the use of steel scrap high in copper. In this case, metallic components of the charge other than the scrap should below in copper, or a sufficiently high ratio of pig iron to scrap should be charged to dilute the copper from the scrap, so that the average copper content of the melt will be below the required maximum.

Jan 1, 1944

By M. M. Slotnick

IT was once aptly said that a sign of approaching senility is ceasing work on a subject and beginning to talk about it. Perhaps that explains why, after many years in which part of my duties has been the training of college men in various branches of petroleum exploration geophysics, I have now begun to talk about it. In making an outline of what I believe ought to be discussed under the general heading of the title, I found it almost impossible to subdivide the ideas into an ordered set of discrete subjects. Rather, the pertinent remarks seemed to interlock almost everywhere. The consequence is that it will be necessary to start with the conclusions and then try to justify them by jumping back and forth. However, based on the types of men with whom I have had to deal, the subject naturally divides itself into two parts. In the first part, I should like to deal with the case of those undergraduates whose natural bent is toward the physical sciences and who may decide to enter the geophysical fold as a career. The other part will deal with those many men, geologists and engineers for the most part, who have drifted into exploration geophysics by one means or another, and whom it is necessary to train for geophysical work while they are occupied in their routine jobs. Here it may be in point to remark that most men in exploration geophysics at present have been developed from precisely the latter group, and that the problem of training here is of great importance even though, in this paper, it will perforce occupy the secondary place. TRAINING OF A GEOPHYSICIST The outstanding reason for the perplexing problem on the training of a geophysicist is that ideas differ on the answer to the question: "What is a geophysicist?" In any of the scientific "specialties," like physics, for example, it is relatively simple to pigeonhole a man as being qualified to call himself a physicist. That appellation applied to an individual does not mean that he has mastered only the branches of intellectual endeavor usually associated under the broad name of "physics." We expect him also to have a more than mere acquaintance with mathematics and chemistry and some understanding of most of the other sciences. But note this important point-we expect our physicist, whom we have chosen as an example, to be intelligently trained so that, if necessary, he can and will know how and where he can get the proper information on a subject in which he is not a specialist; he will know how to absorb that information and turn it to his uses. It seems to me that this is the outstanding characteristic of a man who can truly call himself a scientist: that he is a specialist in one of the broad branches of science and that he has enough training and discipline in the scientific approach so that, when called upon to do so, he can intelligently absorb knowledge from another bordering science (and all sciences not only border upon one another to some extent, but more often, overlap one another), and

Jan 1, 1941

By R. Schuhmann

PROBLEMS in expressing, interpreting, and using size-distribution data recur in many phases of mineral dressing; therefore it is desirable that size analyses be expressed in such a form, either numerically or graphically, that comparisons can be made readily. The size distribution of comminuted material is a result of a specific physical operation on the material and therefore should be governed by some definite physical principle, or cause-effect relation. Although this principle has not been discovered, it has been found that the size distribution of comminuted, homogeneous solids may be expressed by relatively simple mathematical equations. Two equations in particular, proposed by Gaudin1 and by Rosin and Rammler,2 respectively, have stood out, both having wide demonstrated ranges of application. The form and the method of application of the two appear almost irreconcilably different on the surface, but, as will be shown, they are asymptotic in the fine sizes when expressed in the same units. This paper gives the results of a further study of the Gaudin and Rosin-Rammler relations, made with the object of developing a form of size-distribution equation that will be more usable and more significant-particularly in comminution studies, both for interpreting the nature of size distribution and for evaluating surface. The work is summarized in the following: I. An equation relating cumulative per cent finer to particle size in the fine sizes is derived from Gaudin's original equation. That equation relates weight per cent retained on one size and through the next larger size in a geometric series of sizes to size (of the retaining screen, for example). 2. Comparisons with Gaudin's equation and with the Rosin-Rammler equation show that the cumulative equation applies to the fine sizes of all size distributions that fit either of these earlier relations, and, furthermore, has some advantages over each. 3. A simple graphical method of surface calculation based on the cumulative-equation plot is evolved and illustrated. 4. Additional confirmation of the cumulative equation was obtained in the more severe test of sizing down to the limit of a sedimentation balance a sample of jaw-crushed quartz. The equation was closely followed over a 20o-fold range in size, from approximately 0.4 mm. (35 mesh) down to 0.0023 mm. (2.3 microns), the lower limit of the size analysis made. There is no indication that the equation will not hold further to well below 2.3 microns. 5. Calculations of the surface produced in the jaw-crushing test mentioned above showed that at least 8o per cent of the total new surface was on particles finer than 35 mesh (about ½ 5 of the crusher setting). The minus 35-mesh portion was only

Jan 1, 1940

By Frank Ruskey, Richard G. Burdick

Many problems associated with potential hazards in a proposed mining area may not be adequately appraised because of the complexity of trying to evaluate them in terms of production requirements. Frequently, encountered hazards have to be dealt with by day-to-day operational schemes that require the miner to either force a way through them or avoid them by blocking off the area in which the hazards are known to exist. These considerations, after the mine is in full production, can be costly to the mine operator and can increase the danger to the miners. A hazard-evasion computer program for mine planning that will appraise proposed mine layouts on the basis of existing or potential hazards has therefore been developed. The program is intended for use during the planning phase of a mine, where it should assist the mining engineer in making decisions in mine design, With the output from this program, the mining engineer should be able either to corroborate his judgments made on the basis of mining experience or to find unanticipated solutions to design problems. The program tests hundreds of possible solutions to a mining layout, and by sorting out the 10 best (based on a criteria of minimum-abandoned-coal) limits the number of choices that need to be considered and appraised for applicability to a given mine scheme.

Jan 1, 1976

By Jens P. Nielsen, W. H. Justice

This paper describes an improved acidizing technique which has been applied in acidizing gas wells in the La Gloria Field. Wells acidized in this manner exhibited a much greater increase in deliverahility than wells acidized in the conventional manner. The acid is injected into the well in small slugs separated by a small volume of high pressure gas. The acid and gas are displaced from the tuhing by high pressure gas to reduce the hydrostatic head on the well when the acid is recovered from the well. The well is opened for production as soon as the acid and gas are displaced. This procedure permits a very rapid recovery of the acid which results in large increases in the deliverability of the gas wells. It has been found advantageous in the acidization of gas injection wells to inject the high pressure gas directly after the acid without backflowing the acid out of the well. This practice has made it possible to inject the gas in the injection wells of this field with a much lower pressure differential. This reduces the horsepower required to inject the gas and also decrease:, the number of injection wells required per reservoir. INTRODUCTION The results obtained by acidizing gas wells ill the La Gloria Field have varied considerably in the past. For this reason. a planned study of the acidizing procedure was undertaken in order to obtain more consistent results. The Frio Sands of the La Gloria Field are rather permeable and it was not necessary to acidize many of the wells when they were originally completed. At the completion of an eight-year cycling program in several of the gas reservoirs, it became necessary to recomplete many wells in other reservoirs. It was found that the opan Flow potential of the wells recompleted in different sands was not as large as wells that were originally completted in that reservoir. A study of the drilling records of several of these wells indicated that the sands had originally been subjected to considerable hydrostatic drilling fluid overload while the well was being drilled to the deeper sands of the field. It is indicated that during this eight-year period, the drilling mud and water that were lost into the formation when the well was being drilled had formed a relatively impermeable Eone around the well bore. This impermeable zone around the well bore made it very difficult to obtain high deliverability wells when the original wells are recompleted in other zones. Muskat' has shown that in uniformly permeable and porous formations a zone of partial plugging one ft in radius around the well would drastically decrease the productivity of the well. The analysis for this problem shows that the production capacity of a well is very sensitive to the value of the permeability of the zone immediately surrounding the well bore. This is to be expected in view of the highly localized character of the pressure drop in a radial flow system about the well center. The reduction of the deliverability is not proportional to the thickness of the mud-affected zone as the major portion of the reduction in deliverahility IS caused hy the

Jan 1, 1952

By R. W. Raymond

This name is applied to the present mining law, as enacted in 1872 and since, to indicate its leading characteristic—in which it differs from all previous mining laws of this or any other country. The earlier act, passed in 1866, was practically the first attempt of Congress to deal with the question of mining titles upon the public domain. It was framed after nearly twenty years of acquiescence on the part of the Government in the self-constituted tribunals, officials, rules, and customs of the mining districts. In its recognition of these, and in several other particulars, the act of 1866 was open to serious criticisms. It is the purpose of this paper, not to trace the history of legislation on this subject, or show in detail what were the faults of the earlier law, but rather, by a discussion of certain aspects of the present law, to point out how great a revoluition it has effected in the rights of mining locators, and to indicate some of the difficulties attending its application. In the attempt to correct the vagueness of the act of 1866 an entirely new elernent was introduced into the law, bringing with it a new set of difficulties. Under the act of 1866 and the miners' customs which it followed, the lode was the thing claimed and subsequently acquired by patent. And the claim to a given number of feet on the longitudinal course of the lode was rooted in 'a discovery of any part of the lode in any part of the claim. ("Extensions" could in many districts—perhaps universally—be located and claimed on the strength of the discovery in the principal claim to which they referred; but this is a point not essential to the present discussion.) It was not necessary to find the outcrop or the upper edge of a lode in order to lay a valid location upon it. An explorer, sinking a shaft and intersecting a lode not already discovered and claimed by another, could claim by that discovery the number of feet along that lode which the local laws might permit (not exceeding the maximum set by the United States statute) whether his sur-

Jan 1, 1884

By G. H. Clevenger

(Continuing the discussion of the paper of James Johnston, presented at the New York meeting, February, 1914, and printed in Bulletin No. 85, January, 1914, pp. 107 to 133.) This paper cannot fail of being of great interest and value to all who are interested in the cyanide process, on account of the important developments which it records. Mr. Johnston is to be commended for the large amount of detail which he gives, and the company and its management for permitting the publication of data of this character, which while of great value to others could well be considered private property. It might be discussed from a number of standpoints: First, as an example of recent practice in mill and cyanide plant construction; second, the mill practice; third, the cyanide practice; and fourth, the new features in cyanide treatment involved. Perhaps a more vivid way of expressing it would be : First, the equipment or tools with which the various operations are carried on, are they the best and most efficient which could have been selected for their respective uses; and, second, is the best use in every case made of these tools? It may be well inquired is the highest possible recovery of silver made at the lowest cost per ounce recovered? For after all, the making of the greatest ultimate profit is inseparably associated with successful metallurgical practice; there must therefore be at all times a careful balance maintained between recovery and cost of obtaining it. I wish to call attention in a very general way to the equipment used and to an anticipation of questions which are bound to arise in this connection. However, the. bulk of my discussion will be confined to the presentation of certain additional data, together with a more or less general discussion showing the line of development which leads up to the present practice and .the applicability of certain features of it to similar problems elsewhere. There are a number of vital points of broad general interest involved in Nipissing low-grade practice upon which metallurgists will by no means be agreed to which I wish to call particular attention in the hope that it will lead to the presentation of data y others of practice in other districts which will' assist in reconciling this divergence of opinion.

Jan 7, 1914

By F. Lynwood Garrison

It is not intended to make in the present paper any deduction or to formulate any theories from the results obtained by experiments. The further expenditure of considerable time and labor would be required to obtain a sufficient basis for positive assertions as to the microscopic structure of the different varieties of iron and steel, and the structural changes which take place in them. It is therefore my purpose at this time to offer simply a synopsis of the general results arrived at in a few months' work, a brief description of apparatus used, and a few hints as to the preparation and preservation of the material which it is intended to investigate. The study of the microscopic structure of iron and steel is not altogether new. Some attention has been given it in both England and Germany. But the foreign publications on the subject have thus far been confined, so far as I am aware, to two papers, one by Herr Martens, of Berlin, contributed to the Verein zur Befoerderuny des Gewerbfleisses and the other a lecture by Dr. H. C. Sorby of Sheffield. Dr. Sorby, it seems, was induced to investigate the subject as bearing on the structure of meteoric iron ; and the results he obtained are certainly very interesting. At the Boston meeting of this Institute, in February, 1883, Mr. J. C, Bayles called attention to the subject in a neat and exceedingly interesting paper, in which the work of Messrs. Martens and Sorby was summarized,* and original suggestions were added. It is at present difficult to say what will he eventually the practical value of the microscope, thus employed, in the sciences of engineering. The role which it seems most likely to play is that of' an adjunct to the testing-machine, and not (as some have supposed) a rival to the chemical laboratory. That it will be a most valuable accessory seems, to say the least, highly probable. I need hardly go at length into the details of preparing the material for examination. Mr. Bayles has described the process in such a plain and comprehensive manner that if his instructions are

Jan 1, 1886

By B. L. Thane

Within the past few years, the mining industry has taken a new impetus in all its branches. New mines are being opened every day, while old ones, which have been either working at a loss, or have been compelled to shut down, are now gradually being reopened and placed on a paying basis. This growth and new life is due, in a measure, to the discovery of new mining districts, but the most important cause of the progress is the wonderful advance that has been made in all branches of mine-engineering. By means of the important inventions and discoveries that have been made in mechanics, chemistry, and electricity, we are now able to work ores which, only a short time ago, would have been regarded as worthless. We find, for instance, the electrician eliminating two of our greatest difficulties, those of distance and superior elevation, while the mechanic has brought to the highest degree of perfection, not only ore-crushing and hoisting machinery, but all such devices as pertain to the mechanical handling of ores, and, at the same time, the metallurgist, with his combined chemical and mechanical skill, has helped us to extract the precious metals from the most refractory of ores. But when we turn to examine methods in actual use for

Jan 1, 1900

By H. G. Moulton

THE INCREASING scale of mining operations over the past decade, particularly in connection with the exploitation of large bodies of comparatively low-grade copper ores, has made necessary the study of the behavior of rock under failure. When extractions of as high as 40,000 tons a day are reached in steam-shovel operations and as high as 20,000 tons per day in underground mining operations, it is evident that excavations soon become of such size that the behavior of the rock will often be dependent on fundamental principles applicable to more or less homogeneous materials under stress, rather than on weathering or local planes of weakness. In the ordinary rock excavations encountered in civil-engineering practice, such as excavations for subways, highways, railroads, etc., rock faces are not carried to depths sufficient to develop any pressures, or consequently any failures, except those due to loose masses resulting from local planes of weakness. When, however, orebodies whose tonnage is measured by hundreds of thousands are to be extracted by steam-shovel operations in open pits, it is necessary to determine if possible in advance the slopes that the sides of the pits will assume, for these slopes influence the shape of the excavations and thereby the amount of ore that may be extracted by the open-pit method. When large orebodies are mined underground at depths of 300 to 500 ft. (91 to 152 m.) by caving methods, the surface subsiding as the ore is withdrawn, it is necessary to determine in advance the outermost limits of fracture in the subsiding surface, for on the delineation of these limits depends the location of surface improvements, mills, smelters, etc. and also the location of development work, such as hoisting shafts, main haulage levels, and all other underground openings that must remain undisturbed during the period of ore extraction. Heretofore, in civil-engineering practice, it has been assumed that earth and rock behave differently in failure. For the calculation of earth

Jan 2, 1920

By C. N. Schuette

The material presented in this paper has been gathered by the writer during a long and varied experience on matters pertaining to the quicksilver industry. During the past 18 years he has visited practically all of the quicksilver mines of the United States and has had occasion to review the literature on quicksilver mining the world over. In a previous publication1 the conclusion was expressed "that the greatest opportunity for increasing the economy in quicksilver production lies in giving more attention to the geology of the deposits ... " The present paper is a contribution toward that end. Due to a lack of correlation of the observed facts, a great deal of confusion exists in the views of various writers concerning the mode of occurrence of quicksilver ores. This paper attempts to show that certain common factors underlie the formation of all quicksilver orebodies. It attempts to present a framework on which to marshall the observed facts and thus make clear the interrelation of various observations which at first sight appear to be contradictory. The material presented is fragmentary in many respects and it is hoped that readers familiar with the deposits mentioned may supply the deficiency. The reader is asked to refer to the publications cited for maps and additional information on the individual orebodies, as this review, in covering so much territory, must necessarily confine itself to a bare outline of the facts concerning each occurrence. The writer hopes that this paper will elicit comment and criticism from the many competent men interested in the quicksilver industry and to all of them he would express his indebtedness for the many courtesies that they have extended to him at various times in the past. Theory op Primary Concentration The mode of occurrence of any given orebody presents an individual problem to the miner engaged in exploiting it. No two orebodies are exactly alike in their geological relationships, therefore an understanding, in detail, of the geology is necessary if the orebody is to be exploited in the most economic manner.

Jan 1, 1931

By AIME AIME

On Nov. 11, 1909, M. Alexandre Pourcel, of Paris, France, upon the proposal of a large number of distinguished members, and the unanimous recommendation of the Council, was elected by the Board of Directors an Honorary Member of the Institute. M. Pourcel has devoted forty-three years to the metallurgy of iron and steel ; and the work which he did between thirty and forty years ago constitutes an important part of the founda¬tion of the practice of to-day. Among his striking contribu¬tions are : (1) his perfection, in 1869, of the manufacture of high-grade ferro-manganese in a carbon-lined open-hearth furnace, instead of the costly crucibles previously used; (2) his discovery, in 1874, of the method of making solid steel cast¬ings; (3) his manufacture, in 1875, of ferro-manganese and silico-spiegel in the blast-furnace; and (4) his anticipation, in 1875, of modern American blast-furnace practice, by the pro¬duction, in a very small furnace, of Bessemer pig containing 2.5 per cent. of silicon, from a burden yielding only 46 per cent. of iron, and with a consumption, per ton of pig, of only 1,8401b. of coke, containing 15 per cent. of ash. These brilliant pioneer achievements, together with his contributions to cur¬rent technical literature, won for him the Bessemer gold medal of the Iron and Steel Institute ; the great" medal of honor," which is the highest award of the French Society of Mineral Industry, and other gold medals, as well as the distinction of honorary membership of the Comité des Forges de France, which was conferred upon him in 1891. In recent years, M. Pourcel has been instrumental, as consulting engineer of the Société de Commentry-Fourchambault, at Decazeville, France, in an extraordinary development of the manufacture of special steels. The Invar plant, of this company, is said to make a greater variety of such steels (includ-

Dec 1, 1909

By Barry K. McMahon

Following minor slope failures at the commencement of mining the west wall of the Kanmantoo Mine was redesigned from an overall slope between haul roads of 55° to 46°. This decision was based on a probabilistic analysis which indicated that 46° was the optimum economic slope.

Jan 1, 1983

By R. W. Diamond

THREE mills are now operated by the Consolidated Mining & Smelting Co. of Canada, Ltd:: (1) The Sullivan concentrator, Chapman, B. C. (near Kimberley, B. C.), (2) the St. Eugene concentrator, Moyie, B. C., and (3) the Tadanac (customs) concen-trator, Trail, B. C. Differential flotation is the only concentration method employed in all three plants. Tables are used for pilot work only. Flotation equip-ment and control are similar in the three mills, and the flow sheets at the St. Eugene and Tadanac mills, while much simpler, are modeled after that of the Sul-livan concentrator. Successful differential flotation of Sullivan ore com-menced in the spring of 1920, in the pilot concentrator at Trail. During 1920, 193,804 tons were treated by this process. This operation continued without interrup-tion and with steady growth. For the first 7 months of . 1923, which concluded the pilot plant operation, ap-proximately 1100 tons were treated daily. I believe the Sunnyside plant of the United States Smelting &. Refining Co. was the only successful and large scale operation practising differential flotation prior to 1920. in North America. The Sullivan ore, because of its high iron content, was quite a different problem from that at Sunnyside. The entire tonnage of Sullivan ore had to be separated into three sulfide concentrate products-lead concentrate, zinc concentrate and iron concentrate. The choice and arrangement of equipment, and the original flow sheet for the Sullivan concentrator were controlled by the results of the exhaustive pilot mill test. These covered a continuous period of 3 1/2 years and involved the treatment of 1,076,368 tons of Sullivan ore. Satisfactory recoveries are made from feed; 11.0 per cent lead and 7.5 per cent zinc in the form of lead concentrate containing 69 per cent lead, 4.5 per cent zinc, and zinc concentrate containing 3.0 per cent lead and 49 per cent zinc. (The pure zinc mineral in Sulli-van ore is marmatite, 'containing approximately 54.5 per cent zinc and 10 per cent iron. It is apparent, there-fore, that 49 percent concentrate is high grade for this particular ore.)

Jan 8, 1927