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Robe River is ready to go. After seven years of extensive drilling, sampling, pilot plant studies, negotiations with Japan and Australia and agonizing ups-and-downs in financing, this $300 million iron ore project in Western Australia is all set to rush project development to the production stage. Preliminary engineering completed, the combined efforts of Japanese, U.S. and Australian mining concerns will proceed with construction of the project's mining, processing, pelletizing and shipping facilities.

Jan 1, 1970

By Edwin B. Douglas

The Blackbird mine is owned by Calera Mining Co., subsidiary of Howe Sound Co. The mine is located in the Salmon National Forest, Lemhi County, Idaho, about 22 miles west of Salmon and 220 miles north of Pocatello. The thought of producing cobalt from a prospect that offered excellent opportunities stimulated everyone connected with this project. But as time went on, it was found that every phase of the development presented unusual difficulties.

Mar 1, 1956

By I. Iwasaki, R. Titi-Manyaka

Chlorination and chloridization behaviors of pyrite, pyrrhotite, marcasite, chalcocite, covellite, galena, sphalerite, heazlewoodite, and elemental sulfur were investigated by thermogravimetric analysis. The possible reaction mechanisms are discussed on the basis of the theoretical weight changes and thermodynamic considerations. Chlorine is a more effective chloridizing agent than hydrogen chloride. In the light of the experimental results, a scheme for producing nonferrous metal chlorides, molten sulfur, and ferric oxide from complex sulfide flotation concentrates is discussed.

Jan 1, 1974

By Gerald Edmunds

The liquidus line on the phase diagram for temperature versus composition of a binary alloy system, representing the boundary between the homogeneous melt and the heterogeneous melt plus solid, besides showing the minimum casting temperature, is useful in determining eutectic compositions and the presence of phase changes such as peritectic transformations and intermetallic compound formation. The liquidus often is determined by the cooling curves of thermal analysis, but supercooling frequently occurs, so that the temperature values are low. An alternative method, the one employed here, consists of determining the composition of samples of the melts from heterogeneous alloys that are at equilibrium. With meticulous attention to fundamentals, this method is capable of yielding values limited in precision only by the temperature control and measurement and analyses. Apparatus By starting, on the one hand, with a supersaturated solution and allowing the excess solute to precipitate, and on the other hand with an undersaturated solution and allowing more of the solute to be dissolved, both processes being carried out at the same temperature, equilibrium may be said to have been approached from both directions; that is, from above and from below. If the analyses show the solutions to contain the same fraction of solute when equilibrium has been approached from above and from below, one is assured that equilibrium has been reached in both determinations. In order to carry out such determinations, it is necessary to have equipment for obtaining and maintaining the proper temperatures; for holding the melt, measuring its temperature, and stirring, sampling and analyzing it. The present work required temperatures from 420° to 900°C. The equipment consisted of: A furnace, which was a vertical alundum tube, 13/4-in. diameter inside and 18 in. long, wound with Nichrome resistance wire, surrounded by a 3-in. i.d. alundum tube wound for 5 in. of length near each end, for compensation of end losses. This muffle was contained in an iron shell with Transite end plates, the intervening space being packed with Sil-O-Cel. The outside dimensions of the furnace were 12 in. in diameter by 181/2 in. in height. Heating current was supplied by three independent variable-voltage transformers (Variac), one connected to each end compensator winding and manually controlled, and one connected to the main winding through a series resistance of 5 ohms. This resistance was short-circuited for

Jan 1, 1944

By Gerald Edmunds

The liquidus line on the phase diagram for temperature versus composition of a binary alloy system, representing the boundary between the homogeneous melt and the heterogeneous melt plus solid, besides showing the minimum casting temperature, is useful in determining eutectic compositions and the presence of phase changes such as peritectic transformations and intermetallic compound formation. The liquidus often is determined by the cooling curves of thermal analysis, but supercooling frequently occurs, so that the temperature values are low. An alternative method, the one employed here, consists of determining the composition of samples of the melts from heterogeneous alloys that are at equilibrium. With meticulous attention to fundamentals, this method is capable of yielding values limited in precision only by the temperature control and measurement and analyses. Apparatus By starting, on the one hand, with a supersaturated solution and allowing the excess solute to precipitate, and on the other hand with an undersaturated solution and allowing more of the solute to be dissolved, both processes being carried out at the same temperature, equilibrium may be said to have been approached from both directions; that is, from above and from below. If the analyses show the solutions to contain the same fraction of solute when equilibrium has been approached from above and from below, one is assured that equilibrium has been reached in both determinations. In order to carry out such determinations, it is necessary to have equipment for obtaining and maintaining the proper temperatures; for holding the melt, measuring its temperature, and stirring, sampling and analyzing it. The present work required temperatures from 420° to 900°C. The equipment consisted of: A furnace, which was a vertical alundum tube, 13/4-in. diameter inside and 18 in. long, wound with Nichrome resistance wire, surrounded by a 3-in. i.d. alundum tube wound for 5 in. of length near each end, for compensation of end losses. This muffle was contained in an iron shell with Transite end plates, the intervening space being packed with Sil-O-Cel. The outside dimensions of the furnace were 12 in. in diameter by 181/2 in. in height. Heating current was supplied by three independent variable-voltage transformers (Variac), one connected to each end compensator winding and manually controlled, and one connected to the main winding through a series resistance of 5 ohms. This resistance was short-circuited for

Jan 1, 1944

By David J. Mack

A survey and critical appraisal of published information about Young's modulus was originally made by the writer because of a complete lack of information about this very important quantity in works on. mechanics, physical metallurgy, physics, and other sciences. It was felt that a comprehensive summary of such information about Young's modulus might be of general interest and may suggest new problems or lines of attack on other problems that involve E. Hence this paper has been prepared even though it is only a review, with no new ideas or experimental data. The references are only those used in assembling the paper. No attempt was made to compile a complete bibliography on the subject of Young's modulus. CalculatioX oP YouNg's Modulus from Theoretical or Empirical CoNsidera-tions Many attempts have been made to compute E from theoretical considerations. The earliest calculations were probably those of Tomlenson (1883) and Souther-land (1891), but Fess'enden4',~ made extensive calculations a few years later and arrived at the relationship: £ = 78.TOw(i)* where V is the atomic volume. In 1923, Peczalski, working from the same standpoint but with more information available on atomic structure, arrived at an identical relationship, which he expressed as: where B is a constant of value about 8 . 107, p is density and mis atomic weight; the atomic volume, of course, being ml p. Portevind4 immediately pointcd out that while the equations of Fessenden and Peczalski were true of the common metals, they gave low values for the refractory metals with high moduli (Fig. I). He showed (Fig. 2) that much better concordance was obtained by means of an empirical equation of the form: F- KT" where K is a constant; T the absolute melting point; V, atomic volume, and a and b constants of value approximately I and 2 respectively. This constant K in the Portevin equation is not necessarily the same for all elements, as shown by Thompson. Other equations for E based upon theoretical considerations have been derived by Honda and Yamada49 and Lasareff.50 The most recent calculations of elastic moduli based upon quantum mechanics are probably those of Fuchs He extended the method of Wigner and Seitz for calculating the lattice energy and compressibility of monovalent metals and computed the elastic constants of lithium, 18

Jan 1, 1946

By Otto Wartenweiler

After the phenomenal development of the new mine, the United Eastern Mining Co., with Mr. Frank A. Keith as President, decided to install a reduction plant. The character of the ore, closely resembling the product of other mines in the district, did not offer any particular metallurgical problems, since these neighboring mines had been operating milling plants very successfully for several years. Thus, with the general metallurgical treatment fairly well-defined, the matter of next importance was to design and construct a plant as economically as possible, that would give the best results obtainable. The ore consists of a mixture of calcite and quartz in about equal quantities, with some decomposed andesite, while the average value of mill feed was calculated to be $20 or more in gold, no silver being present. The tonnage to be treated at the start was fixed at 200 tons, but, in view of the favorable condition of the mine, it was considered advisable to arrange facilities for increasing the capacity to 400 tons. While it is best in some cases to adopt a distinct independent unit system where future enlargement is contemplated, in this instance the plans worked out differently. Summarized, the treatment adopted consists of coarse crushing, coarse grinding, fine grinding and cyanidation. For coarse crushing the selection of the No. 6 size gyratory crusher was governed not so much by its capacity as by the size of the feed openings to receive the run-of-mine material, which was too coarse for a No. 5 crusher. TO accomplish the coarse grinding to best advantage, a careful comparison was made between the modern steel ball-mill—the last word in crushing and grinding—and one of its older, and, at that time better-established, competitors, the rolls. The following conclusion was reached: While it is possible that for the sized plant under consideration the cost of operating rolls might be a little cheaper, it is preferable to use ball-mills because a simpler arrangement is possible, and because the handling of ball-mills is preferred by the operator. A marked departure was introduced for fine grinding. Instead of the long type of tube-mill, using pebbles, a mill of similar design was selected, but of much shorter length, using small cast-steel balls as grinding medium. For cyanidation, the Dorr continuous countercurrent process was

Jan 1, 1918

By J. B. Mudd

Introduction It is difficult to think of any activity on which mankind has been more dependent than mining, and certainly there is much evidence in almost every part of the world of old workings that clearly demonstrate that man from earliest times has dug and toiled to take from the earth precious stones, metals and materials that from time to time have been essential or of value to him. In step with social development and industrial and technological advances the tempo of mining activity, regulated only by the laws of supply and demand, has quickened and in this century has accelerated rapidly in keeping with its dramatic development. Indeed, the rate of change of events has been such that if it were to continue to accelerate as fast as it has over the past decade there is reason to wonder how the insatiable demands for metals and minerals are to be met in the years that lie ahead. Shallow mines containing high-grade ore deposits either have been or are being rapidly mined out and their place can only be taken in general by ore lying at greater depth, or by ore of low grade, situated for the most part in remote and in underdeveloped areas. The cost of exploration and development is rising at an alarming rate, with the result that the expenditure now required to bring a mine to production far exceeds anything previously contemplated. It is estimated that the total capital required to maintain existing operations and develop new ones during the next 5 years will be of the order of $50,000 million and of this, new capital to bring new mines to production will be of the order of $3,000 million. Today no single mining finance company can, from its own resources, find all the money for a major mining development, and as a consequence there has been a strong trend toward joint ventures and to the formation of multinational consortiums. International lending institutions already play an important part in financing many new mining projects and their participation provides the financial umbrella under which other lenders can invest with greater security. There is little doubt that to finance the costly ventures in the future, governments and international lending agencies, banks and finance

Jan 1, 1971

By D. J. McAdam, G. W. Geil, R. W. Mebs

AS shown in previous papers by the authors 9-l7† the resistance of a metal to fracture, like its resistance to plastic deformation, is a function of all three principal stresses.‡ A technical cohesion limit is the technically determined resistance to fracture under a specific stress system. The technical cohesive strength thus comprises an infinite number of technical cohesion limits corresponding to the infinite number of possible combinations of the principal stresses. The technical cohesive strength, therefore, may be represented by a surface in a diagram with the three principal stresses as coordinates. As shown in previous papers, 9-I8 the technical cohesive strength increases with plastic deformation, with decrease in temperature, and with increase in the strain rate. The technical cohesion limit, therefore, is affected by the same factors that affect the flow stress, § namely, the stress system, plastic deformation, temperature, and the strain rate. More- over, the influence of each of these factors on the technical cohesion limit has been shown to be qualitatively similar to the influence of the same factor on the flow stress.9-18 Advance of knowledge about the conditions determining fracture, of metals has been retarded by the reluctance of some investigators to abandon preconceived ideas about how metals "should" behave. The incorrect idea is still prevalent that the conditions determining resistance to fracture are very different from those determining the flow stress. Attempts are still being made to express resistance to fracture in terms of a single parameter, such as a limiting value of the greatest principal stress, the maximum shearing stress, or the volume stress (one-third the algebraic sum of the three principal stresses). In these attempts, a sharp distinction is sometimes made between a ductile or "plastic fracture " and a "brittle fracture." In making this distinction, however, the meaning attached to the term "brittle fracture" sometimes is not made clear. The term could mean fracture after very little plastic deformation or it could be used to designate the type of fracture. An ordinary fracture of a ductile metal at room temperature starts as a cleavage, generally transverse to the direction of the greatest principal stress, but eventually changes to a shearing fracture. In some conditions, however, the metal fractures entirely by cleavage, with no evidence of plastic deformation during the fracture; the surface of such a fracture may have a

Jan 1, 1947

By Lawrence K. Jetter, Robert F. Mehl

SOME advances have been made recently in the theory of the kinetics of precipitation from metallic solid solution despite the complexities of the problem, but there is surprisingly little quantitative information available on rates of precipitation with which to test present theory or upon which to build new theory.‡ Attempts to measure rates of precipitation have been beset with difficulties which originate both in the anomalies that attend the changes in the properties selected for measurement, as, for example, in electrical conductivity or mechanical properties, and also in the complexities in the structural changes in some systems, as in the aluminum-copper system. If the functional relationship between the quantity of precipitate and the value of the selected property is uncertain, measurements of that property are obviously of uncertain utility in determining absolute rates of precipitation. If the precipitating system passes through one or more transition stages, the interpretation of measured rates lacks definiteness; in such cases, it is necessary to measure the rate of reaction in each separate stage, if the rate measurements are to have any significance from the kinetic point of view.* These difficulties cannot be wholly avoided, for at least in some measure they are characteristic of the process of precipitation from solid solution, but they can be minimized both by the selection of a simple system and by the use of a method of measurement relatively free from anomalous behavior. The present paper reports dilatometric measurements on the rate of precipitation of silicon from the aluminum-rich solid solution in the aluminum-silicon system-a study that approaches the desiderata of simplicity. The aluminum-silicon system offers advantages from these points of view: there are no known anomalies in the property changes accompanying precipitation; 2.3,4 there are no known transition stages; the precipitate is an element, not a compound, and both matrix and precipitate are cubic, and while the structures are not identical (the solid solution is face-centered cubic and the precipitate is diamond cubic), the system at least approaches the ideal case of a crystal precipitating from a matrix of the same crystal type-the ideal case which Becker5 assumed in treating the precipitation process theoretically. The dilatometric method, while not free from disturbing effects, as the subsequent dis-

Jan 1, 1942

US 4,185,077 - In the recovery of uranium from a solution produced by leaching uranium ore, the leach liquor is contacted with a polymeric crosslinked vinyl benzyl chloride anion exchange resin and eluted with sulfuric acid to recover uranyl sulfate Such a resin is resistant to attrition and thermal degradation during elution. R.L. Albright, assigned to Rohm & Haas Co Jan. 22, 1980. 6 pp (423-7). Filed: 10-31-75 (627,829).

Jan 1, 1982

By C. F. Willis

Many of the failures in vocational education are due to the fact that the educational methods were not designed to the capabilities, habits, and environments of those to be trained; rather they were based on the policy that education is education and lessons are lessons, whether for youngsters of fifteen or for men of forty. Vocational education among miners involves, first, a study of the men themselves, their habits, and the use of their leisure time; second, a study of the differences between the methods of teaching required for men and for children. Certain fundamental requirements of training methods for miners are reasonably universal and may be applied with success to any ordinary mining community. The rate of labor turnover is another consideration; it would be useless to design a four-year course for men who remain in one place only a few months. Length of Course The first consideration should be the length of the course. Few mining communities have a sufficiently stable population to make it possible successfully to carry on a course for over a year. While some men might complete a four-year course, the number is comparatively small compared with the number to whom a shorter course would be of service, and it is better to raise the standards of education even a little for a large number than to raise them to a high level for a few. It is perfectly possible to attain both objectives by arranging the courses in small units; all the units, when grouped together, should comprise a fairly complete course, yet any one unit should be complete in itself and of benefit to the workman. It should not take many of these units to make a miner or a timberman out of a mucker; but to do this the course should be short, because muckers seldom stay in one place long. By grouping a number of these units together it Would be possible for a miner to become a shift boss or a shift boss a foreman, and so on. As far as possible the units of the course should not be dependent on those preceding or following. The workman understands the completed job but he is not accustomed to carrying on several jobs at the same time and

Jan 1, 1920

By R. W. Smith

An amine used as a collector in a commercial flotation process is usually a rather impure substance. The differences in ionization constants and solubilities of various amines undoubtedly affect their collecting power or strength. This investigation explores some of the differences among several amines of similar (although not precisely the same) chain lengths. An attempt is made to relate the differences to both observed contact angle and Hallimond tube flotation behavior in quartz systems.

Jan 1, 1974

By John Birkinbine

A RETROSPECT of the growth of the production of pig-iron for the past half century would be the history of the invention and introduction of heated blast as applied to the smelting of iron ores. As the apparatus employed was improved in conception and construction, the economical operation of the furnaces to which it was attached was the more marked, and the production correspondingly increased. To compare the original iron box placed over a coal fire with the modern hot-blast stove, with its combustion-chamber, gas-burners, and air-regulators, would be as unfavorable to the former as to contrast the product of the little Blauöfen with the yield of the improved furnaces of to-day. But, as these little Blauöfen were the germs from which the larger plants have grown, so from the crude apparatus invented and applied by Neilson has grown, in the face of great opposition, the more economical hot-blast stoves now in use. It is not surprising that an innovation like heated blast should have received a large amount of attention from metallurgists, nor that men of recognized ability should formerly have been found both among its champions and opponents, but it is remarkable that, at the present day, with the results of careful research and thorough experiment compiled in convenient shape for perusal, there are iron¬masters who still consider it economy to allow the products of combustion to escape into the atmosphere, rather than utilize them in heating the blast, because of a supposed injury to the quality of the product. In the present state of knowledge and practice, it is proper to express as an axiom, that a well-constructed hot-blast apparatus is essential to the economic operation of an iron-producing plant. Of the interpretation of proper construction there is of necessity a variety of opinions, and, with the view of solving the problem, the apparatus for heating blast has from time to time assumed various forms. Boxes, cylinders, and pipes, placed horizontally, vertically, inclined, or in circles and spirals, have been tried ; there have been pistol-shaped pipes, double pipes, divided or diaphragm pipes, siphon pipes, and as much variety in the mains, connections, flues, and setting. It is probable that, to the introduction of the bell and hopper in

Jan 1, 1876

By John Birkinbine

A retrospect of the growth of the production of pig-iron for the past half century would be the history of the invention and introduction of heated blast as applied to the smelting of iron ores. As the apparatus employed was improved in conception and construction, the economical operation of the furnaces to which it was attached was the more marked, and the production correspondingly increased. To compare the original iron box placed over a coal fire with the modern hot-blast stove, with its combustion-chamber, gas-burners, and air-regulators, would be as unfavorable to the former as to contrast the product of the little Blauöfen with the yield of the improved furnaces of to-day. But, as these little Blauöfen were the germs from which the larger plants have grown, so from the crude apparatus invented and applied by Neilson has grown, in the face of great opposition, the more economical hot-blast stoves now in use. It is not surprising that an innovation like heated blast should have received a large amount of attention from metallurgists, nor that men of recognized ability should formerly have been found both among its champions and opponents, but it is remarkable that, at the present day, with the results of careful research and thorough experiment compiled in convenient shape for perusal, there are ironmasters who still consider it economy to allow the products of combustion to escape into the atmosphere, rather than utilize them in heating the blast, because of a supposed injury to the quality of the product. In the present state of knowledge and practice, it is proper to express as an axiom, that a well-constructed hot-blast apparatus is essential to the economic operation of an iron-producing plant. Of the interpretation of proper construction there is of necessity a variety of opinions, and, with the view of solving the problem, the apparatus for heating blast has from time to time assumed various forms. Boxes, cylinders, and pipes, placed horizontally, vertically, inclined, or in circles and spirals, have been tried; there have been pistol-shaped pipes, double pipes, divided or diaphragm pipes, siphon pipes, and as much variety in the mains, connections, flues, and setting. It is probable that, to the introduction of the bell and hopper in

By R. M. Stewart

INTRODUCTION Requirements for achieving economic slope stability in open pit mining must not only be met during the operating stages but in all preceding stages of mine development. In many operating mines little or no emphasis was ever placed on evaluating the stability of possible slopes during the exploration and planning stages. The purpose of this discussion is to emphasize the necessary considerations that should be made in all stages of development in order to achieve the safest and most economic pit slopes. The most economic slopes may not always be the safest slopes and it is incumbent upon the mine operators and engineers to achieve an optimal combination of economics and safety. The stability requirements outlined are based on the profit motive and are, therefore, practically oriented. Long-term basic research or theoretical studies are considered important only to the extent that they can be shown to have a definite payoff. Consideration will first be given to the information required for stability analysis, which can be determined during the exploration and evaluation stage, followed by further stability work necessary during the mine planning and layout stage. Particular emphasis is then placed on the operating stage in which blasting, dewatering, artificial stabilization, and slope failure are discussed. Lastly, the importance of a logical and orderly research procedure is stressed. EXPLORATION AND EVALUATION STAGE The purpose of the exploration and evaluation stage in the mining scheme is to find and delineate a potential orebody. Discovery and delineation commonly involve drilling tens and in many cases hundreds of boreholes. These boreholes, which may cost as much as $20.00 per foot of depth for a cored hole, are usually abandoned once drilling is completed. Stability evaluation for a potential open pit should begin at this stage by taking advantage of the existing boreholes. Rock and soil properties, as well as hydrologic parameters, may be obtained from both the borehole and the core. Seismic velocity and neutron probes may be used to log the borehole to obtain elastic moduli data. A borehole dilation jack may also be used to give backup information on the rock and soil elastic parameters. Use of a core orientation system can result in the determination of fault and joint frequency and distribution. Before splitting or otherwise disturbing the fresh core, qualitative evaluation

Jan 1, 1972

By Philip Henry

THERE is a difference of opinion among engineers on the subject of depreciation in general, and still more on its application to any given case. The committee which was appointed by the American Society of Civil Engineers to make a report on Valuation of Public Utilities, states "There is no subject connected with valuation about which there are more diverse views than those relating to depreciation;" and in the discussion which took place upon the presentation of the preliminary report of this committee in January, 1914, that part of the report dealing with depreciation called forth more discussion than any other. From this discussion it was evident that the word " depreciation" was not always used in the same sense, so it is quite important that some definition be adopted. As this paper relates to the proper method of treating depreciation by corporations or individuals operating oil properties, both of which must make a return of annual net income to the government in connection with the income tax, it will be in order to adopt the definition of the Internal Revenue Bureau. Under date of Mar. 29, 1910, the Commissioner of Internal Revenue of the Treasury Department stated "Deduction on account of depreciation of property must be based on lifetime of property, its cost, value and use." Again, on Form 1035, "Return of Annual Net Income" for miscellaneous corporations (Section 2, Act of Congress approved Oct. 3, 1913), a deduction from gross income is allowed for "Total amount of depreciation for the year." This item is defined more particularly as follows: "The amount claimed under Item No. 5 (b) for depreciation should be such an amount as measures the loss which the corporation actually sustains during the year in the value of buildings, machinery, and such other property as is subject to depreciation on account of wear and tear, exhaustion, or obsolescence. The amount taken credit for on this account in order to be allowable should be so entered on the books as to constitute a liability against the assets of the corporation. The amount claimed under this item should not cover losses in the value of stocks and bonds. Decrease in the book value of securities owned, so far as such decrease represents a decline in the actual value of such securities, should be deducted under item 5 (a) of the return.

Jan 1, 1915

By H. D. Wilde

At the Sugarland and Raccoon Bend fields in the Gulf Coast area, all wells are drilled with rotary tools and the casing is always set in cement that is placed by the circulation method. After the cement is set, the rotary mud that fills the hole is not withdrawn or bailed out; consequently, it is not customary to give the cementing job a direct test either by putting pressure on the hole to see whether the cement will hold or by observing whether an effective water shut-off is secured. About three years ago, this company started the practice of coring the cement left in the bottom of the casing and examining the core thus secured. If the core was hard and strong, the cementing job was judged a success but if the core was incoherent, soft, and crumbly, the job was considered a failure. Of course, there were intermediate types of cores and it was not always a simple matter from this examination to decide whether the job was a success or failure. After about two years, a summary of the core examinations that had been made indicated that of cementing jobs made at depths of 1000 ft. or less, 60 per cent.. were failures; of those between 1000 and 2000 ft., 80 per cent. were failures, and of those between 3000 to 6200 ft., 100 per cent. were failures. This sta,rtling table emphasized the need of the study of the conditions under which the wells were cemented and of adopting means to reduce the percentage of failures. In addition to these core tests, two wells gave direct evidence that the cementing jobs were not always successful. In one, a four-year-old well at Goose Creek, the casing was perforated, and when fluid was circulated some of the old cement wss brought to the surface. Most of it was powdery and the few chunks that were brought up were soft and crumbly. The other was a well at Raccoon Bend which during a blow-out brought a number of chalky, soft and crumbly pieces of cement to the surface. Suggested Explanations of Cementing Failures Efforts were made at once to explain the causes of these cementing failures. As all of the cements used were of a high grade and gave

Jan 1, 1930

By H. M. Howe

(Read at. the Lake George Meeting, October, 1878.) MANY direct processes have been proposed for the treatment of oxidized ores of copper by reducing the copper oxide to the metallic state, and by separating it from its impurities by a subsequent fusion. The radical objection common to all the methods which have come to my notice, except those in which sulphur plays the prominent part, is that the very deoxidizing agent which effects the reduction of the copper oxide, inevitably reduces at the same time a very considerable part, if not the whole, of the iron which almost invariably accompanies copper in its ores. The result is that, when the ore is subsequently fused, a very great quantity of the already reduced iron separates from the slag along with the copper, alloying with it, and necessitating costly subsequent operations for its separation. Thus, at Perm, in the Urals,* the product of the fusion of ferruginous copper oxides is a mixture of one hundred and fifty-five parts of highly cupriferous pig iron with two hundred and five parts of very impure and ferruginous black copper, containing some 10 per cent. of carbon and iron, though free from sulphur, and of course very difficult to refine. If, in order to avoid this reduction of iron to the metallic state, the reducing action be made feebler, it inevitably results that a considerable part of the copper as well escapes deoxidation ; and, consequently, the slags are so rich that it becomes necessary to treat them subsequently in order to recover the copper which they contain. Thus, in treating native copper, at Lake Superior, where the reducing action is purposely made feeble in order to prevent the deoxidation of the iron, the slags from the first fusion of the ore carry so much copper as to render it imperative to treat them again, which is done in a cupola. And yet, in spite of so far weakening the reducing action as to cause a notable slagging of the copper, a very considerable reduction of iron actually takes place. These are the two dangers which threaten the smelter of oxidized copper ores. If he wishes to avoid slagging his copper, he must have so strong a deoxidizing action as to reduce a great deal of his * Rivot, Prineipes Généraux du Traitement des Minerais Métalliques, i, p. 79.

Jan 1, 1879

By Charles S. Robinson

The Henderson ore body is east of the Continental Divide in the Front Range of the Colorado Rocky Mountains, about 80 km (50 miles) west of Denver. The ore body is being developed for mining by workings that extend more than 1100 m (3500 ft) below the topographic surface. During construction of the mine workings, ground water in fractures in cystalline rock has been encountered. From 1969 to 1973, Charles S. Robinson & Associates, Inc., in cooperation with the engineering and geologic staffs of the Climax Molybdenum Company, a division of Amax Inc., studied the ground water geology of the Henderson mine development area. Detailed geologic record( of the Henderson mine were available as a result of the exploration, evaluation and development of the mine. Records of the flow, chemical composition and temperature of the ground water at and near the surface, from the entire mine, from portions of the mine, and from exploration holes drilled in the mine, were kept as the mine was developed. Where possible, ground water pressures in drill holes and changes in pressure with time, were recorded. The geologic, hydrologic and chemical data were correlated. The following conclusions were drawn from the correlations: The ground water in the Henderson mine occurs in fractures in Precambrian igneous and metasedimentary rock and in a series of Tertiary intrusive rocks. Two zones of ground water were recognized; an active zone, in which the fracture systems are recharged and discharged annually into the surface water system, and a passive zone, in which the fractures were filled with water in the geologic past. Discharge from the passive zone is through mine workings that intersect the fracture systems. Discharge from a fracture or fracture system is initially high but decreases with time. The rate of decrease in flow (or pressure) is exponential. By measuring the change in flow with time, it is possible to calculate the amount of flow at some given period of time in the future. Based on changes in rate of flow and pressure, and the geology, and assuming rates of mining of the ore, it will be possible to predict the volumes of water that will have to be handled during the life of the mine and the area around the mine that will be drained by the mining operation.

Jan 1, 1979