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By W. Joseph Schlitt

The characteristics of successful heap and dump leach operations are first reviewed in a general sense. Then attention is focussed on solution management as the key operating parameter in leaching. The first part of this study includes a detailed conceptual analysis of fluid flow. This identifies the relationships between the flow parameters and the chemical and physical properties of the rock. Then these relationships are extended to practical systems in order to establish optimum application rates and solution distribution methods for heaps and dumps. The study shows that there is a maximum effective application rate, qmax, that can be used without causing solution short circuiting. This rate is a function of the minimum permeability in the heap or dump. The expression for qmax is qmax (gal/ft2/hr)[~]0.9 k (darcies). Here k is the appropriate permeability coefficient. Using this equation, qmax is found to be on the order of 1 gal/ft2/hr (4 cm/hr) for a typical heap or dump leach operation.

Jan 1, 1984

By R. A. Pallanch

SODIUM sulfite as a zinc retarding agent in the selective flotation of complex lead-zinc sulfide ores was discovered by the writer in the summer of 1919 in the testing laboratory of the U. S. Smelting, Refining & Mining Co.'s gravity concentrator at Midvale, Utah. It proved to be the first reagent to give consistently good results in the laboratory on the company's Bingham ore. In December, 1919, C. A. Lemke, concentrator superintendent, recommended that a flotation unit be added to the existing gravity mill to handle the mill slimes, using sodium sulfite as the zinc depressant. Owing to the poor lead and zinc markets and the unfavorable royalty schedules offered by the Minerals Separation Co., the project fell through at this time. In 1921, a number of laboratory tests were made at Midvale on other ores, among them ore from the Sunnyside mine at Eureka, Colo. Both sodium and calcium sulfites were used with success on this ore. Early in 1923, further tests were made at Eureka, shortly after the Sunnyside company had resumed operations after a two-year shutdown. As a consequence sodium sulfite was given a trial in the mill. The results showed sufficient improvement over previous work as to warrant continuous use of this reagent in the lead circuit. Except for a week or so in 1926 and for several weeks in April, 1927, when sodium cyanide and zinc sulfate were given trial runs in this mill, sodium sulfite has been used ever since. Sodium sulfite was chosen rather than the calcium sulfite because of its greater solubility, making it possible to introduce the reagent as a solution. This solution is introduced into the Marcy ball mills along with the original feed of ore. The consumption of sodium sulfite in the Sunnyside mill varies from ¼ to ½ lb. per ton of ore, the smaller amount probably being nearer the average. In February, 1924, laboratory work at Midvale demonstrated conclusively that good results could be obtained on the company's Bingham ore and on most of the custom ores tested by using sodium sulfite as the zinc depressant, xanthate as the lead enhancer in the lead circuit, followed by copper sulfate and additional xanthate to float the zinc. Sodium sulfide was used to float the iron pyrite after the lead and

Jan 1, 1928

By Joseph Hays

MORE years ago than I care to admit I conferred the title of "combustion engineer? upon my-self since nobody else would confer it. I thought at the time, and for some, years thereafter, that my field was limited to the precincts where the fuel was being burned, but I found that I could stand in the door of the furnace room and hear distressed heat units calling for help all over the plant. Some of them were over-worked, others were compelled to do useless work, and still others, anxious to render a proper account of themselves, were not permitted to do any sort of work at all and were utterly wasted. The combustion engineer has something to do at that interesting occasion when the heat unit is being born in the furnace, but his responsibility does not end there. He must follow the little fellow throughout the entire period of its hectic existence in the plant and see that it gets a fair chance and a square deal everywhere. I fear that the general impression of the combustion engineer's duties is much as mine was in the beginning; that his job is limited to the implements and processes incident to the specific operation of converting fuel into active, heat energy and of applying it to the boiler, the still, or what-not, with the least possible waste. But is it not true that a heat unit saved in a remote corner of the plant means just as much to the fuel account as another saved at the furnace? And if nobody else is looking after the heat units out on the range why should the combustion engineer spend all of his time hanging around the corral? If combustion engineer is not a broad enough title to cover the man in charge of a general heat unit rescue campaign call him any-thing else you please. The job is all that counts. The name means nothing. A skunk by any other name would smell as bad. The greatest field I have ever found for general "heat rescue" work is the oil refinery. In refining we first put heat into the oil and then take it away from the vapor. The greatest heat losses occur during the cooling operation, but there are losses, many of them preventable, either wholly or partly, at every step of the several processes in oil refining.

Jan 3, 1928

By J. C. Bowling

The services provided by consulting engineers to the mineral process industry are briefly described. The organization of a multi-discipline consulting firm is outlined. Finally, the role of a consulting engineering firm is amplified by a description of its activities in the design and construction of a mineral process plant from inception to start-up.

Jan 1, 1978

By P. C. Keith

IT is difficult to talk about atomic energy and the engineer without repeating a number of phrases that have been worn smooth with use Mr John M. Hancock has spoken to you of the two-sidedness of atomic energy, one useful, and the other destructive. If a control plan of the type that he has outlined is adopted it will be perfectly possible to go ahead with the peacetime development of atomic energy Failing the adoption of such a plan, emphasis will of necessity be placed upon the perfection of atomic energy as a weapon of destruction I want to speak, however, in the hope that atomic energy will be developed for peace-time use, and speak about the role of the engineer Before I can do that I must, outline the framework within which the engineer must work, and then I would like to go back and tell of some of the things that he has done, in the hope that that may throw some light on what he may be expected to do in the future Last year the McMahon Committee the Senate Committee charged with drafting domestic atomic-energy legislation-held extensive hearings in an effort to strike a balance between the negative attitude of what to do about atomic energy and the positive attitude of what to do with it Out of these hearings grew the United States Atomic Energy Act, calling for a civilian commission to exercise control over all atomic-energy activities in this country As you

Jan 1, 1947

By HARRISON W. CRAVER

LIBRARIES are universally recognized as essential to modern civilization. In a world that gets most of its learning through the printed word, storehouses of print are a vital necessity. In this regard engineering differs in no way from the other learned professions, but until recent times the library needs of engineers have received rather scant attention. When the engineering profession was more of an art and less of a science than it is today, when each problem was solved more through the results of experience than by applying scientific principles, literature was less helpful. The engineer of today, however, is aware that his activities rest upon a scientific foundation and consequently comprehensive books dealing with more limited fields are now being published. Another difficulty for the operating engineer in the past was that the published works on engineering were written chiefly for use as college texts. A third obstacle to the development of engineering libraries has been the lack of librarians with experience in engineering.

Jan 1, 1938

By E. P. Shea

The Anaconda Co.'s Geological Department at Butte, Mont., was started early in the Company's history because of litigation involving vein ownership and extralateral rights. The problems, some of which were resolved in courts, were many because of the large number of veins and lode locations. Defensive action was required to prove ownership and protect against illegal exploitation of the downward and extra-lateral extensions of the ore bodies. In many cases it was necessary to define the outcrop of the vein and to show that its apex was within the boundaries of the lode claim. Exhibits illustrating geology were needed to present the cases clearly, and these could be made only after careful inspection and mapping of the underground workings by competent geologists. Also, The Anaconda Co. was one of the first companies to recognize the worth of skilled mining geologists and the value of accurate records in the search for new ore. The department was organized in 1900 by H. V. Winchell who, with D. W. Brunton, worked out the methods. Reno Sales was Chief Geologist from 1906 until 1948 when he was succeeded by V. D. Perry, the present Chief Geologist. Under their direction, F. A. Linforth, M. H. Gidel, C. H. Steele, E. P. Shea, C. C. Goddard, Jr., and W. A. O'Brien enlarged the scope of the work and improved the technique.

Jan 3, 1961

By Hans W. Schreiber

INTRODUCTION At the end of the day, the decision by the sponsor to proceed with a project and to seek financing, or the decision by the financier to grant financing are made on a judgmental basis. Cash flow projections, sensitivity and risk analysis, the innumerable ratios applied by the financier, the so-called feasibility study, etc. are all only tools, and the degree to which they affect decisions is as highly varied as are the personality differences and business conduct and outlooks of the persons who render the decision of "go or no-go". The independent consultant, then, is expected to provide an additional increment of credulity and/or reliability to the "tools" which others will use in reaching a decision; the consultant is really not in a position to directly recommend a "go or no-go". PROJECT FINANCE INGREDIENTS The project finance situation has basically three ingredients: - The project; - The inherent risks attendant with project failure; - The parties. The project, to be viable for financing, will have certain essential characteristics, namely: 1. Clear title or rights to the mineral; 2. Proven definition/establishment of mineral quantity; 3. Financial viability; 4. Physical access consistent with financial viability; 5. A market for the product at a price and for the quantity consistent with financial viability; 6. Transportation/shipping from the project facility to the market at a cost consistent with financial viability; 7. Availability and demonstrated expertise of the developer of the facility; 8. Demonstrated expertise of the operator of the facility; 9. Production processes do not involve unproven new technology; 10. Availability of management personnel; 11. The property and the facilities have value (and thus can be used as collateral); 12. Government approvals/support, as required, will have been obtained; 13. The political environment is essentially friendly and stable; 14. The owner(s) of the project have the financial, strength to make equity contributions consistent with total required investment capital and project risk; 15. Backing by credit support other than that of the financier (i.e. guarantees); The inherent risks of failure are (Nevitt, 2nd Edition); 1. Completion delays with consequent delays in the generation of revenue 2. Cost overruns 3. Technical failure 4. Financial failure of contractors 5. Government interference 6. Uninsured losses 7. Increased price or shortages of raw materials, supplies 8. Technical obsolescence 9. Loss of competitive position in the market place 10. Expropriation 11. Inadequate/poor management The parties directly or indirectly integral to the project financing are: - The mineral rights owner - The developer - The operator - The equity investor

Jan 1, 1985

By E. M. Wise

IN a previous communications the improvement in strength, harden-ability and color, occasioned by replacing gold in a typical gold-silver-copper alloy by various amounts of platinum, or palladium, was discussed. In the present paper the results of further studies upon the constitution and the nature of the hardening transformation in these alloys are pre-sented. This research may be summarized as follows: 1. The liquidus and solidus have been determined for the alloys of the palladium and platinum series. Cooling curves were utilized for deter-mining the liquidus of the palladium alloys but this method proved unsuitable for the platinum alloys so that a, novel quenching method was utilized for the latter. Both the liquidus and solidus of the palladium alloys increase steadily with the palladium content. The liquidus of the platinum alloys increases rapidly with the platinum content, while the solidus temperature increases with the platinum content up to about 14 atomic per cent platinum, but suffers no further increase with additional increments of platinum up to 20 atomic per cent at least, owing to a peritectic reaction. 2. Palladium, and even more effectively platinum, reduces the rate of grain growth. Owing to this fact and to the increase in the solidus temperature, "overheating" does little or no damage to alloys containing reasonable quantities of these elements. This is confirmed both by tensile tests and metallographic examination. 3. The excess phase present in one of the high-platinum-content alloys has been isolated and chemically analyzed and was found to consist almost wholly of platinum, gold, and copper, evidently derived from the compound AuCu, by the partial replacement of gold by platinum.

Jan 1, 1933

By E. M. Wise

THE practice of dentistry, particularly the construction of artificial dentures and "bridges," involves a unique and difficult application of the precious-metal alloys. Appliances used in the mouth are continuously exposed to corrosive agencies which can hardly be described as mild, and must remain free from tarnish and be substantially immune to corrosion. Limitations with respect to space and weight demand high physical properties, while complexity of form requires ease of working. The high corrosion resistance required necessitates the use of alloys of high precious metal content. The usual expedient of resorting to mechanical working to produce the requisite strength and stiffness cannot be utilized because of the frequency of annealing and soldering operations. To meet these difficult conditions manufacturers of dental goods were early led, unknowingly perhaps, to the production of precipitation-hardening or temperable alloys. The excellent properties of iridium-platinum may have suggested the addition of platinum metals to the conventional gold-silver-copper alloys to produce greater strength and hardness. It was found that such quarternary alloys retained their high physical properties after passing through the usual soldering process; i, e., heating to 7500 to 8000 C. and cooling naturally in the air. Later it was discovered that they could be softened and rendered more ductile by heating to the same temperature and quenching, in water. These early examples of precipitation hardening, for years the common knowledge, of dental practitioners and laboratory technicians, escaped the attention of the scientific world and discovery of the transformation which was responsible for this hardening was discovered by the Russian investigators of the system Au-Cu, Kurnakow, Schemtschushny and Zasedatelev,(1) § although the optimum conditions for securing good properties in aged alloys were not given attention.

Jan 1, 1932

By Thomas A. Wright

No symposium on die casting could be complete without consideration of the methods of formula and impurity control. No consideration of control would be complete without discussion of that new tool of the analytical chemist and inspector, the quartz spectrograph. Just as there is an increased appreciation of the possible applications of the die-casting process and of die castings, so too is there, slowly but surely, of the spectrograph. At present the role of the instrument might well be compared with that of brass or magnesium die castings. Neither is as widely understood or known as they will be. Product specifications are increasing and are getting more explicit and often more rigid. The designer, metallurgist and production engineer or superintendent will be forced to depend more and more on the chemical laboratory. Sampling, as well as analyses, testing and inspection problems will grow. The chemical laboratory must meet its increased responsibility and use of the spectrograph will become more common. Advantages of increased precision, greater speed, lessened labor and often lower costs cannot be ignored. It will be the purpose of this paper in part to outline the respective fields of chemical and spectrographic analyses and to indicate where one may overlap the other and in part to indicate certain possible sources of contamination of zinc-base die-cast alloys in particular. COMPOSITION Aluminum.-Aluminum die castings are expected to conform to the specifications of the American Society for Testing Materials1† and the Society of Automotive Engineers2. The A.S.T.M. has recognized seven

Jan 1, 1935

By Thomas Wright

No symposium on die casting could be complete without consideration of the methods of formula and impurity control. No consideration of control would be complete without discussion of that new tool of the analytical chemist and inspector, the quartz spectrograph. Just as there is an increased appreciation of the possible applications of the die-casting process and of die castings, so too is there, slowly but surely, of the spectrograph. At present the role of the instrument might well be compared with that of brass or magnesium die castings. Neither is as widely understood or known as they will be. Product specifications are increasing and are getting more explicit and often more rigid. The designer, metallurgist and production engineer or superintendent will be forced to depend more and more on the chemical laboratory. Sampling, as well as analyses, testing and inspection problems will grow. The chemical laboratory must meet its increased responsibility and use of the spectrograph will become more common. Advantages of increased precision, greater speed, lessened labor and often lower costs cannot be ignored. It will be the purpose of this paper in part to outline the respective fields of chemical and spectrographic analyses and to indicate where one may overlap the other and in part to indicate certain possible sources of contamination of zinc-base die-cast alloys in particular.

Jan 1, 1935

By B. M. Larsen, T. E. Brower

INTRODUCTION AND SUMMARY BY "thermochemical factors" we refer to those variables which affect the net heat which must be put into the bath in order to make a heat of steel from any given set of charge materials. This is admittedly only one phase of the production rate problem. The whole problem includes also consideration of rate of charging, flame radiation intensity, rate of optimum fuel input obtainable without undue damage to the furnace structure and any variations in conditions such as stirring, slag volume or viscosity which affect the rate at which heat can flow down and away from those exposed surfaces where the heat is first received from the flame. Because a given type of charge in a shop is often considered as being nearly constant in both physical and chemical characteristics from one heat to another, and because such a state of affairs may be thought of as resulting in a reasonably constant net heat requirement, this requirement is usually neglected as an invariable, inevitable matter, about which nothing can be done. With normally variable charge, and variable percentages of limestone and cold pig, however, the net heat requirement can be subject to very appreciable change; it may also be affected by such things as the currently popular procedure of blowing oxygen into the bath, To bring the general problem of production rate into better perspective, therefore, it seems worthwhile to try to evaluate the net bath heat requirement and the amount by which it may change through variation in different factors. Because our calculated values of net heat are admittedly uncertain, we have tried to check them in part by statistical data on actual production rates over rather large groups of commercial heats. The results of calculation of net heat requirements in a wide range of actual commercial practices may first be summarized briefly. We find a wide range between the extremes of different practices, as would be expected, with duplex practice (essentially blown metal plus hot metal) having essentially a zero net heat requirement, an all-cold charge practice somewhat over 1 million Btu per ton of steel and a high hot metal practice about 0.75 million Btu per ton. Over the commercial range of scrap plus hot metal practice, increasing the percentage of hot metal from 40 to 78 pct, with other factors nearly constant, decreased the net heat by only some 5-10 pct, The net heat is increased by about 1.2 pct for each I pct of the metallic charge present as cold pig. Calculated values of oxygen supplied by air varied from about 25 up to 60 lb per ton of steel, and in a 60 pct hot metal practice, an increase from 32 to 52 lb oxygen from air decreased the calculated net heat from 0.88 to 0.74 million Btu per ton. Use of pure cold oxygen to substitute for about one half of the total charge ore (about 28 lb oxygen replacing 145 lb ore per ton of steel) decreased the

Jan 1, 1948

By Eli Sani

Investment in the mineral industries-particularly in the mining industry-differs from investment in nonminera1 industries in that the latter have an indeterminate life, assumed to be perpetual, and are not called upon to replace the firm's original investment. In mining ventures, on the other hand, once the ore bodies are depleted the mine has no economic value; the original capital investment must be returned to the investor by the time the ore is exhausted. A mining venture is also characterized by the significant cost and time associated with the exploration phase. A myriad of samples must be taken, geological features investigated, and ore grade assured. In addition, most mining ventures require substantial capital expenditures aggregating several hundred million dollars for a number of years before the project begins producing any revenue. Any theoretical model employed in evaluating a mining venture, as well as similar mineral ventures, must take all these factors into consideration.

Jan 5, 1977

By Herbert K. Kutter

This paper is concerned with the physical phenomena in the fracture process of presplitting and only indirectly with the establishment of the optimum presplitting parameters. Its nature is therefore qualitative, rather than quantitative.

Jan 1, 1968

By Herbert K. Kutter

This paper is concerned with the physical phenomena in the fracture process of presplitting and only indirectly with the establishment of the optimum presplitting parameters. Its nature is therefore qualitative, rather than quantitative. Before examining the problem of presplitting, it is first necessary to study the phenomena which occur when an explosive charge is detonated in a borehole. To do this it is desirable to consider the action of the explosion wave separately from that of the expanding gases.l In the theoretical analysis such a separation poses no problems. Experimentally this was accomplished by use of an underwater-spark discharge to generate the stress wave and by pressurized oil to simulate the pressure of the explosion products. The main role of the wave is to generate a densely radially fractured zone around the borehole. The subsequent gas pressure, exerted against the walls of a highly (radially) fractured cavity, generates a quasi-static stress field (henceforth referred to as static stress field). This stress field was found to be the same as that of a pressurized cylindrical "equivalent cavity" with a radius equal to that of the crack tips. Under these conditions the quasi-static stresses become appreciable and cause further extension of the radial cracks. It was further found that, under gas pressure, the longest of the radial cracks would extend first, and extension of two diametrically opposed radial cracks requires the least pressure. From these observations concerning the single shot the transition to a whole series of more or less simultaneous shots, as in presplitting, can readily be made. In the case of multiple shots, as in presplitting, exactly the same effects occur, but at numerous locations and sufficiently close in time that they interfere with

Jan 1, 1968

C W. ROLFE, Professor of Geology, Emeritus, has of-fered a prize of $250 for the most valuable contribu-tion toward a new, better, or increased use of any mineral resource of the State of Illinois. The prize is open to anyone engaged in research, either privately, commercially, or in connection with any univer-sity or college staff, or any state or national bureau or sur-vey. The work must have been done, or at least completed, curing the year named. Three copies of the paper or books must be in the hands of the chairman of the committee on or before 6 p. m., May 1, 1928. If an unpublished paper is submitted, it should be typewritten, double spaced, on 8 1/2 by 11-in. paper. Unpublished results of study, or papers or books pub-lished since May 1, 1927, and before May 1, 1928, may be offered in the competition; but the results of the study must show real present or prospective economic value. Address all contributions and correspondence to Rolfe Prize Committee, 209 Transportation Building, University of Illinois, Urbana, Ill.

Jan 3, 1928

By W. M. Peirce

THE PROCESSES USED FOR THE rolling of zinc are not novel or unique in a mechanical sense. There has not been so widespread a tendency toward heavy slabs and mechanical handling, and toward 3-high and continuous mills as has taken place with steel and with some of the other nonferrous metals. Those respects in which the rolling of zinc differs from the rolling of other metals center around two facts. First, the hexagonal zinc crystal has only one plane of easy slip: namely, the basal plane. Fortunately, however, the crystal twins readily on any of the pyramidal planes, thereby creating new basal planes favorably oriented for relief of the stress which has caused twinning. Second, the recrystallization temperature of zinc is little above room temperature and for very pure grades of zinc may in fact, be at room temperature for severely strained material. The practical effect of these two characteristics of zinc will become evident in the later discussion. First, it is necessary to give some attention to the melting and casting of billets for rolling. Reverberatory furnaces are commonly used for melting. These vary over a wide range of capacity from as low as 5 tons to 100 tons or over. Low-frequency electric furnaces have also been used with satisfactory results. Arc Furnaces are, of course unsuited to a low-melting and lute-boiling metal, such as zinc. To minimize oxidation and volatilization losses in the furnace, the temperature should be kept below 500°C. With this temperature in the melting furnace, a suitable pouring temperature in the neighborhood of 460°C can he maintained at the mold when a transfer ladle is used for pouring.

Jan 1, 1948

By Thomas E. Leontis

INTRODUCTION THE importance of magnesium alloys in the manufacture of aircraft engines has been realized for many years. A concentrated effort has been exerted in the laboratories of the Dow Chemical Co. to develop magnesium-base alloys with improved properties at elevated temperatures whereby greater advantage can be taken of the inherent lightness of these materials. In an earlier publication,1 attention was called to the superior tensile properties and resistance to creep of cerium-containing magnesium alloys at temperatures up to 700°F. More recently, additional data on magnesium-cerium alloys have been furnished by Murphy and Payne.2 The present paper deals with the mechanical properties of sand-cast magnesium alloys containing zinc, at temperatures up to 500°F. The study includes binary Mg-Zn† alloys containing up to 10 pct zinc and several ternary and some polynary alloys based on the Mg-1Zn,†Mg-3Zn, Mg-4.4Zn, Mg-6Zn, and Mg-10Zn binaries. The compositional variation in the tensile properties, hardness, and creep at room and elevated temperatures, and in the electrical conductivity at room temperature has been determined. The results of these tests show that many zinc-containing magnesium alloys exhibit resistance to creep at elevated temperatures significantly higher than that of present commercial magnesium alloys, but lower than that of alloys of the magnesium-cerium type. In addition, they have high tensile properties at room and elevated temperatures and high conductivity. This combination of mechanical properties and conductivity indicates that these alloys should be given serious consideration for commercial applications involving exposure to temperatures higher than those to which present commercial magnesium alloys can be taken safely. LITERATURE The properties of sand-cast magnesium alloys containing zinc as a principal alloying element have not been investigated very extensively, especially at elevated temperatures. The following remarks, which are confined to sand-cast alloys, will serve as a summary of the most important references on this phase of magnesium metallurgy. The first recorded determination of the tensile strength of binary Mg-Zn alloys as a function of zinc content was reported by Aitchison.3 Similar studies, including the measurement of elongation and hardness, have been performed by Gann and Winston,4 Dumas and Rockaert,5 Haughton and Prytherch,6 and by Spitaler, the last being reported by Beck.7 A slight superiority in the tensile strength of chillcast Mg + 8 Zn alloy over the sand-cast alloy was noted by Maybrey 8 That alloys of magnesium containing 5 to 12 pct zinc

Jan 1, 1948

By Rossiter W. Raymond

(Read at the Wilkes-Barre Meeting, May, 1877.) THE 12th of April, 1877, witnessed the celebration, at Freiberg, Saxony, of an event profoundly important for the ancient mining industry of that district, and full of interest to mining engineers throughout the world-namely, the connection of the famous Roth-

Jan 1, 1878