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By W. C. Meyer, R. R. Klimpel

A physical model of flotation, derived from viewing froth as a kinetic species since it constitutes the carrier of ore particles, not only agrees with and is simulated by engineering mathematical models, but is statistically verified by actual laboratory flotation data. The model couples the mechanical removal of froth using paddles with the more rapid interactions taking place in the bath. It clearly shows that the kinetics of mass removal is dictated by flotation cell dimensions, paddle speed, and, more importantly, froth characteristics. Some conclusions and model predictions are presented.

Jan 1, 1984

By D. R. Semmes

The possible oil territory of Alabama can be readily divided into two regions, the Paleozoic area of the north, and the Coastal Plain province of Cretaceous and younger formations lying to the south. This latter area has received much attention in the last few years and has been described by a number of writers.' Although the possibilities of the Cretaceous series have been much emphasized by recent writers, the fact remains that the two, or possibly three, localities where oil or gas have been found in anything like paying quantities are confined to the area of Carboniferous rocks. Moreover, almost all of the oil seeps and a good percentage of the gas seeps are confined to this area.2 Topographically, as well as structurally, the Paleozoic area can be divided into three rather well defined provinces: (1) The broad, open Coosa Valley lying adjacent to the crystalline oldland, with comparatively little relief, except for occasional longitudinal ridges and rather intense folding; (2) the plateau region of horizontal or gently warped Pennsylvanian strata broken by occasional anticlinal valleys aligned northeast and southwest, outliers of the Coosa Valley proper, in which the older Paleozoic formations are exposed—a region of much relief (200

Jan 1, 1921

By Richard A. Arnold

The evolution of planning processes in the United States from the early 1900's is briefly examined. From one year operating budgets, planning processes have evolved into sophisticated analyses of alternative long-term future strategies and the management issues and practices which relate to their implementation. Increasing complexity within the business environment has led to numerous planning methodologies and extensive use of computers to analyze operating and financial information. All of these developments, however, have not supplanted the real need for decision-makers to continue to give important weight to the intuitive or soft data inputs into the planning process.

Jan 1, 1985

By Alberto J. Terrones L.

THE classical papers on contact metasomatic deposits by Lindgren on the Clifton-Morenci district,1 by Barrel1 on Marysville, Mont.,2 and by Goldschmitt on the Oslo district, Norway,3 laid the foundation for understanding of the importance of separating the metamorphic process from the subsequent metasomatic stage. Knopf4 made a big step forward by recognizing that sulfide ore minerals are invariably younger than silicates and by further stressing the importance of structural control5 ore finding. Some years later Harrison Schmitt6 fought the idea that contact metasomatic deposits are erratic, irregular, bunchy, economically marginal, and of small size, concluding that these descriptions have little factual basis. He emphasized the importance of detail mapping and careful geological study as fundamental requirements for a better understanding of these deposits. This article presents a comparative description of the structural features at the Magistral, Antamina, Morococha, Vilca, Ferrobamba, Katanga (Quibio), Tintaya, and Huarca contact deposits (Fig. 1). Further, it will describe how these structural features controlled the emplacement of the intrusives, their shape, distribution of metamorphic and metasomatic halos, and sulfide deposition in post-skarn structural channelways. Finally, the modifications introduced by a superimposed hydrothermal stage recognized at some localities will be discussed.

Jan 3, 1958

THE task of the smith who works in iron is very laborious, indeed far more so than that of the coppersmith just described. For he also handles heavy weights continually, and stands constantly erect be- fore the fire of the forge, since the hardness of the iron cannot be softened except by means of heating and boiling it well. In this place he continually moves his body, now thrusting the iron into the heart of the fire with large thick tongs, now removing it to look at it and to put sand, tuff, or other earth over it, now putting on fresh charcoal, now moistening and slowing down the fire, and now cleaning it. Finally, while the iron is hot

Jan 1, 1942

By John L. Schroder, Woods G. Talman

EXPERIENCE has shown that certain known natural conditions and other indefinite characteristics combine to make a mining area vulnerable to mountain bumps. Some of the known conditions are heavy overburden, an overlying stratum of strong non-elastic rock, a structurally strong coal seam that does not crush easily and yet is the weakest stratum in the series, and a floor stratum of more than ordinary firmness. The indefinite characteristics could include resistance of top or bottom of a coal seam to lateral flow, effect of immediate top and bottom strata, nature of the coal seam, and other factors about which very little is known. It is in this area that exhaustive study is needed to achieve positive control of the dreaded mountain bump hazard.

Jan 8, 1958

By George E. Beavers

Under the title used for this paper, the converter practice of the Tennessee Copper Co. is described in the TRansactions of the Institute.l That article contains the following statement: "The limit in capacity of the Peirce-Smith converter in terms of concentrate has not been reached but approximately as high as one ton of concentrate has been handled for each ton of liquid matte charged and good working conditions have been maintained." It is not the intention of the writer to review the conditions leading up to the introduction of a Peirce-Smith converter at Copperhill, but, instead, to offer later data to show how satisfactory the installation has been. Converter Campaign, June 15, 1930 to August 23, 1931 Blowing time (converter days)............... 349.90 Number of blows........................... 427.00 Tons matte charged........................ 38,335.00 Copper assay of matte, per cent.............. 13.67 Tons blister copper made.................... 9,246.00 Time to blow one ton of copper, minutes...... 54.50 Air used per minute, cu. ft................... 12,500.00 Blast pressure, lb........................... 12.80 Air per ton copper, cu. ft.................... 681,330.00 Air per ton iron, cu. ft....................... 199,040.00 Tons flux used............................. 11,845.00 Tons flux per ton matte..................... 0.31 Tons flux per ton copper.................... 1.28 Tons flux per ton iron....................... 0.37 Tons concentrate treated.................... 28,960.00 Copper assay of concentrate, per cent......... 17.13 Tons concentrate per ton matte.............. 0.76 Tons material charged per converter day...... 235.70

Jan 1, 1934

H. D. HIBBARD, Plainfield, N. J. (written discussion *).-While this valuable and timely paper may not go to the root of the matter, it deals with many of the elements and factors involved. It might be taken as the engineer's solution of the case, starting with the assumption that steel is steel, while the tendency for a rail to have transverse fissures may, and probably does, depend, in part at least, on conditions met before it reaches the track. Admitting with the author that "brittleness of fracture in all grades of steel is characteristic of fatigue tests" we may yet look farther back to find out, if possible, why some rails and some steels are more prone to have transverse fissures than others, for it has been found that rails from certain heats of steel developed these fissures under a service which

Jan 3, 1918

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 William H. Callahan

"For his exceptionally successful career as a geological mentor, for his ore-finding skills, and particularly the discovery of the Central Tennessee Zinc District and for his lecture, 'Prospecting in the USA-Promise and Problems.' " Recipient of the 1982 D.C. Jackling Award

Jan 1, 1983

By H. C. Rolseth, R. H. Kohler

Jet channeling made its entry into the granite industry in 1955 and quickly gained acceptance as an economical method of quarrying. Developed by the Linde Division of Union Carbide Corp., this method employs a small rocket-jet burner with a high-temperature, high-velocity exhaust flame that causes granite to disintegrate. It can thus make continuous vertical cuts to free large blocks from granite formations. The Thermal Spalling Process The effect of a thermal device on rock depends upon the rock's spallability. In simplest terms, spalling is the decrepitation resulting from differential expansion of rock crystals due to thermally induced stresses.1 the individual rock properties influencing the spalling characteristic are so numerous and their interaction is so complex that it has so far been impossible to predict with accuracy the reaction of any particular rock to a high-temperature source of heat. Perhaps computers will eventually make such predictions possible, but for the present it is necessary to impose the thermal shock conditions on a sample of the rock to establish its spalling characteristics. The properties most favorable to a high degree of spallability are: (1) Large linear thermal expansion at temperatures below 700º C. (2) High thermal diffusivity at temperatures below 400º C. (3) Equigranular interlocking structure with little or no fine-grained clay or mica alteration products. (4) No significant amounts of soft, low-melting, or elastic minerals or materials which yield after thermal decomposition.

Jan 7, 1969

By D. W. Jessup

ONLY during the past few years, have the old-fashioned methods for treating ores and byproducts progressed to any marked degree. The advent of multiple-hearth roasting, blast roasting, the baghouse, and the Cottrell plant indicate this change. It is the ability to roast and smelt sulfide ores and concentrates that gave this later advance. Further investigations that will solve the problem of efficient handling of flotation concentrates and their attendant ills are of the utmost importance. With future developments, the metallurgist will be able to smelt more economically and to treat still more refractory ores, making the early methods appear small by comparison. GROWTH OF SMELTING Well within the memory of pioneer smeltermen, the ore was charged directly into the blast furnace as it came from the mine;, only the richer, ores were smelted, the lower grade and sulfide ores were undesirable. Matte was, at first, thrown away and only two products) were desired-slag and lead bullion. Scores of the early smelting companies failed because of improper reduction of ores, high costs, short- furnace campaigns, inability to treat sulfide ores, and ores containing-zinc. With the failure of weaker companies, consolidation eliminated many others, until today the field is dominated by a comparatively few organizations, each strong financially. Formerly, a few thousand dollars would erect a small plant, whereas the modern smelter costs over a million dollars. Ore and products to which formerly no attention was paid are now treated with comparative ease and at a good profit. Mechanical improvements have modernized smelting, furnace tonnages show an increase, and metal recoveries have made enormous strides. Even though costs have decreased, they have not dropped in proportion to the improvements, because of the higher wages, greater costs of fluxes and coke, more undesirable ores smelted, etc.

Jan 8, 1925

By David A. Summers, Clark R. Barker, Marian Mazurkiewicz

In May 1975 the U.S. Bureau of Mines contracted with the University of Missouri-Rolla, Rock Mechanics and Explosives Research Center to develop a Hydrominer modification to a longwall shearer unit, wherein the rotating pick-laced drums and connecting gear drives are replaced by a water jet cutting ahead.1 The concept of the water jet cutting head is based on using the high localized energy of the water jets to isolate a slice of coal by cutting a slot under, at the back of, and at the top of the web. The plow blade of the head then advances into the cut and wedges the coal cantilever over onto the conveyor (Fig. 1).

Jan 4, 1978

By I. L. Nichols, D. C. Seidel, D. E. Traut

A fluidized countercurrent ion-exchange system was developed, operated, and evaluated by the Bureau of Mines. The system consisted of integrated multiple-compartment absorption and elution columns in which the solution flows are continuous except for short periods when resin increments are withdrawn. The exchange of uranyl sulfate between a simulated acid leach uranium solution and a strong-base, ion-exchange resin together with the subsequent elution with an acidified sodium chloride solution was studied. The effects of the number of sections, section heights, amount of resin withdrawal, and solution flow rates were investigated. Also examined were the kinetic and equilibrium relationships for the absorption step. The experimental data indicate a strong interdependence between variables. Solution retention time appears to be a major limiting variable. The column was efficient over a range of conditions, but close control was needed for optimum operation.

Jan 1, 1977

By Henry N. McCarl, John J. Dran

The academic community and the larger and more sophisticated mining companies have largely rejected the older mineral valuation methods such as the Hoskold and Morkill concepts and replaced them with "discounted cash flow" (DCF) techniques. The relevancy and usefulness of the older methods have been questioned primarily on the basis of their underlying assumptions that mining companies do not have numerous alternative investments and must use sinking funds deposited at market or "safe" rates of return to recover the purchase price of mineral reserves. The ability to reinvest in numerous (often nonmining) alternative business ventures, the changing purchasing power of the dollar, corporate income and other taxes, depreciation and depletion allowances, and modern financial management practice all militate against the continued use of the older valuation methods, especially for the larger mining companies. Small mining companies and individuals still use these methods largely out of habit and familiarity. The Hoskold Mineral Reserve Valuation Method The Hoskold method was developed prior to the evolution of modern accounting practices and before the days of the corporate income tax. At the time of its development, annual earnings of the firm were represented by the difference between cash revenues and cash expenses and were not subject to taxation by the government. Thus, earnings at that time were equivalent to what is today known as cash flow.

Jan 7, 1974

By L. W. McKeehan

Jan 1, 1934

NORTH AMERICA ALASKA Anchorage,-Ames, M. B. Culver, H. W. Fiedler, H. L. Fox, E. F. Gallemore, W. A. Kreitlow, E. J. Layfield, R. A. Saarela, L. H. Strandberg. H. Candle,-Bobbins, J. S. College.-Fackler, W. C. Joesting, H. R. Swift. R. E. "Wilcox, H. G.. Crooked Creek-Lyman. R. F. Fairbanks.-Beistline, E. H. CANADA Canadian Army Overseas,¬ Ball, H. D. Brides, C. Butterill. H. J. M. Ladner, F. E. Lane, H. C. Millar, R'. A. Murchison, R. G. Passow, F. M. ALBERTA Calgary-Allen, R. E. de Hart. J. B. Dingman, C. W. Furnical. G. H. Gray, J. G.

Jan 1, 1943

By Harrison R. Cooper

Measurement of process material composition with on-line instrumentation has commanded attention of metallurgical plant management as a logical extension of the sampling operation, making possible immediate determination of essential data needed to maintain efficiencies at the highest possible level. The current status of methods employed for online composition analysis of slurries and solid materials is reviewed.

Jan 1, 1984

By L. L. French

Jan 1, 1977

By Kenneth A. Grace

Jan 1, 1985