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By A. M. Gaudin, D. W. Fuerstenau, M. M. Turkanis

SOLUBLE silver salts are effective activators for flotation of sphalerite with potassium ethyl xanthate as collector.' Since sphalerite takes up large quantities of silver ions rapidly," investigation of this system appeared fruitful for studying the mechanism of sphalerite activation and deactivation. Experimental data presented here comprise studies of the mechanism and rates of activation and deactivation of sphalerite with silver and cyanide ions. A 20-lb sample of sphalerite from Ottawa County, Oklahoma, was handpicked, crushed, screened, hydrosized to produce a 65/100-mesh fraction, and purified by electrostatic separation. The sphalerite was then leached with benzene and absolute ethyl alcohol to remove possible organic contaminants and with 0.1 M NaCN to remove any copper that might have been picked up during screening. The benzene had been specially purified by grinding with fine sphalerite for 12 hr to remove trace impurities that might have had a specific affinity for sphalerite. Finally, the mineral was washed, dried in flowing nitrogen, and stored in large ground-glass stoppered weighing bottles under a small nitrogen pressure.

Jan 1, 1957

By D. M. S. Bhatia, Richard D. Hagni

Five sulfide minerals from the Magmont mine, southeast Missouri were sampled for 31 trace elements in over 300 samples by laser microprobe spectrographic analysis of polished sections. The concentration of several trace elements shows a pattern of progressive variation with depth (space) and variation with different paragenetic stages (time) of each mineral. Factor analysis of the geochemical data shows sympathetic correlation both in space and in time of Bi, Cd, Ge, and Sn in galena and sphalerite, and Ni and Co in sphalerite and marcasite.

Jan 1, 1981

By S. P. Goplen, M. Henriksen, T. F. Barron

In the past decade, numerous large scale drilling projects have made use of reverse circulation air lift methods. Reverse air lift pumping can be established by injecting gas into a column of liquid; the subsequently decreased density of the gas-liquid mixture allows atmospheric pressure outside the lift conduit to establish flow. The rate of flow can be controlled by varying the gas to liquid ratio. A typical reverse circulation air lift system is depicted in [Fig. 1]. Allen 1 has described a number of reverse air lift drilling projects. Although cited examples are generally related to large diameter holes, the method has seen use in other applications such as sand dredging, chemical pumping, water well pumping. and continuous coring. One particular benefit obtained with enclosed reverse circulation drilling is elimination of lost circulation. The required air/water ratio for pumping at a given submergence and lift has been established experimentally by Gibbs.2 His data, however, do not reflect sensitivity of flow rate to air/water ratio. Further, in Gibbs' work, air apparently is injec-

Jan 1, 1980

By W. G. Woolf, A. Y. Bethune

Filtration of hot (60°C) supersaturated zinc sulphate solution (sp gr 1.540) from slimy leach residues at the electrolytic zinc plant of Sullivan Mining Co., Kellogg, Idaho, is described. Separation of liquids and solids in the finished leach is by Burt filters modified to meet conditions of high-acid, high-density process for electrolytic zinc. Operating characteristics of the Burt filter on this pulp are presented.

Jan 5, 1950

By E. S. Vargas, T. W. Chapman, Samuel W-S Tse

Models for interphase mass transfer rates in the solvent extraction of metals are developed for zinc and copper chlorides being extracted by trilsooctylamine and for copper extraction by LIX 64N from ammonia solution. The approach is to adopt a stagnant film model on which film thicknesses are known and to derive the interfacial metal fluxes for the case where all reversible reactions are fast and locally equilibrated. A growing drop mass transfer cell is used to measure extraction rates. It is found that for the cases studied the transfer rates are mass-transfer limited On the other hand, copper extraction by LIX from acidic solution exhibits slow reaction kinetics, and earlier kinetics models are confirmed. Interactions that cause varying selectivity in the simultaneous extraction of copper and zinc chlorides are demonstrated.

Jan 1, 1981

By Bernard York

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.

Jan 7, 1953

By B. C. Scott, A. Baker

The Pitch mine of Pinnacle Exploration, Inc. is in the Marshall Pass district, thirty miles east of Gunnison, Colorado. This is a new mining district, having come into existence as recently as 1955, when uranium mineralization was discovered rather late in the days of the uranium boom. There have been three other mines in the district, all of them now inactive. Two of these produced a few hundred tons of very high-grade uranium ore, and the third, Pinnacle's Little Indian 36 mine, produced a few thou- sand tons of lower grade ore. Pinnacle was one of the first companies in the district, and was able to acquire a large acreage. The first two years of exploration were essentially wasted in looking for Plateau-type deposits in a mineralized sandstone bed, but this "wasted" work produced two specific items that paid off. One was an ore-grade outcrop that ultimately became the Little Indian 36 mine, and the other was a boulder of very high-grade uranium ore that eventually led to the discovery of the Pitch mine; however, the actual source of the boulder still has not been found.

Jan 5, 1961

By Donald Ingvoldstad, Harold E. Lee

At Bunker Hill the original charge storage and preparation system was installed in 1917 to accommodate lead-silver gravity mill products. Only minor tonnages of wet fines such as vanner and flotation concentrates were received. Charge flux and diluent requirements were provided by an ample supply of siderite middlings and coarse limerock. While oversize material was crushed through Y4-in., the use of roll crushers in series resulted in a more or less granular, free-running charge of adequate porosity. Under such conditions, receipts could be proportioned directly from receiving bins, and suitable blending was obtained by passing the resultant layered composite through a small Stedman disintegrator. This elementary system served well for production and smelting of an extremely lead-rich sinter, in the low column blast furnace. Here sinter physical quality is less critical, and appreciable quantities of raw flux and oxidized ore may be charged directly to the blast furnace without seriously impairing furnace capacity.

Oct 1, 1956

By Peter F. Howard

Major reserves of phosphorite were found in the Georgina Basin of northern Australia in the period 1966-1968. Geological investigations by various companies and the Bureau of Mineral Resources of Australia show that these phosphorite deposits are associated with siltstones, cherts, siliceous shales, and limestones of the Beetle Creek formation or its equivalents, all of lower Middle Cambrian age. The discoveries resulted from systematic Australia-wide exploration programs by several companies utilizing, in concept, the relation of basin stratigraphy, lithologic associations, tectonics, and phosphate occurrences to paleogeography in respect to its paleolatitude and areas of supposed oceanic upwelling. In terms of field techniques, the first discovery at Duchess, North Queensland, resulted from the recognition of a phosphorite interval at depth in a stratigraphic oil well followed by prospecting of the nearest outcrop of the equivalent aged rock succession. In Northern Territory, the Wonarah-Alexandria deposits, which do not crop out, were discovered by analysis and interpretation of gamma radiation logs followed by drilling.

Jan 1, 1972

By Peter L. Swanson

A microcrack process zone is frequently suggested to accompany macrofractures in rock and play an important role in the resistance to fracture propagation. Attenuation of surface waves propagating through mode I fractures in wedge-loaded double-cantilever beam specimens of Westerly granite has been recorded in an attempt to characterize the structure of the fracture process zone. The ultrasonic measurements do not support the generally accepted model of a macroscopic fracture that incrementally propagates with the accompaniment of a cloud of microcracks. Instead, fractures in Westerly granite appear to form as gradually separating surfaces within a zone having a width of a few millimeters and a length of several tens of millimeters. A fracture process zone of this size would necessitate the use of meter-sized specimens in order for linear elastic fracture mechanics to be applicable.

Jan 1, 1984

By H. B. Charmbury, D. R. Mitchell

Everyone in the coal industry from top management to the preparation engineer is vitally interterested in recovering as much salable coal as possible from the run-of-mine product. Coal losses from a preparation plant occur in the solid refuse material being discharged from the plant and in the bleed-off slurry from the water circuit. The refuse is generally hauled from the plant in solid form by trucks, conveyors, or aerial trams to the refuse or culm banks or it may be crushed and transported by hydraulic methods to refuse ponds or dams. The loss of coal in refuse material and the extent of this problem has been covered in another paper. The loss of salable coal in the plant bleed-off slurry is one of the water circuit problems in coal preparation plants. Slurries originate at various places in the processing circuits and are usually disposed of by transportation to waste ponds known as slurry ponds. Even though the combustible material discharged as slurry and refuse from the plant is labeled a loss, the loss must only be considered temporary. There is a tendency at the present time to examine refuse and slurry losses and to reprocess these materials to recover valuable coal.

Jan 1, 1960

By R. J. Keene

The South Works high-tonnage billet caster was started in late March 1971, with the first heat being successfully cast to completion. Currently, over 31,500 tons per month are being produced. U. S. Steel designed and built this caster with the objective of producing quality-steel billets for critical bar, rod, and wire applications. The essential design parameters were based on studies conducted on the Research Laboratory's pilot caster, also located at South works. 1,2,3)* The caster is a four-strand, straight-mold machine that produces 7.5-inch- square billets at rates exceeding 300 tons per hour. An in-line-reduction mill reduces each strand to either 6-inch-, 5-inch-, or 4-inch-square billets.

Jan 1, 1972

By Gordon A. Gross

Banded siliceous manganese-iron bearing sediments recognized as distinctive facies of Algoma-type iron formation constitute low-grade resources of manganese in many countries. Manganiferous facies associated with oxide and carbonate facies of iron formation have iron to manganese ratios ranging from 0.2 to 2 and commonly about one. Manganiferous facies up to 30 m thick occurring separately or with other iron formation facies are associated with cherts, carbonates, shales, turbidites, tuffs, and lavas. Primary cherty manganiferous facies and their gondite metamorphic equivalents represent significant manganese resources and are protores for higher-grade deposits derived by secondary enrichment processes.

Jan 1, 1983

NEW MEMBERS The following list comprises the names of those persons who became members during the period June 10 to July 10, 1915: Members AGTHE, FRED. THOMAS, Quarry Supt., Atlas Portland Cement Co., Hannibal, Mo. ARTHUR, WILLIAM SEYMOUR, Project Mgr., U. S. Reclamation Service, Williston, S. D. ASH, SIMON HARRY, Deputy State Mine Inspector 503 Alaska Bldg., Seattle, Wash. BALDWIN, C. KEMBLE, Second Vice-Pres. and Chicago Mgr., Robins Conveying Belt Co., 1315 Old Colony Bldg., Chicago, 111. BOGGs, WILLIAM BRENTON, Met Douglaston, L. I., N. Y. BROWN, RALPH DARE, Min.Engr., Asst. Genl. Supt., O'Gara Coal Co., Harrisburg, 111. COLE, A. NEWTON Genl. Supt., Pennsy Coal l O., Clarion Pa. DAVIS, JOSEPH D., Chem Bureau of Mines, Washington, D. C. DEAN, DUDLEY STUART, Treas., Keweenaw Land Association, Ltd., Newport Land CO., 87 Milk St., Boston, Mass.

Jan 8, 1915

By D. A. Kinneberg, J. W. Donaldson, N. J. Themelis

In the Kennecott Converter Smelting process (KCS), copper concentrate pellets are smelted and converted to high-grade matte in a modified Peirce-Smith converter using oxygen-enriched air and fuel. A high-grade matte bath is produced and maintained in the converter. Periodically, the slag layer is skimmed, slowly cooled, and its copper content is recovered by milling. Ladles of matte are transferred and finished to blister copper in another converter. The gases from the Kennecott Converter contain the SO2 products of the smelting and converting processes and can be treated in an acid plant, eliminating the problem of low-concentration gases associated with the operation of the reverberatory furnace. Pilot tests at Utah Copper Division were followed by a full-scale prototype converter test at the Chino Mines Division of Kennecott Copper Corporation. The concepts of the process and the results of this campaign are presented.

Jan 1, 1976

By Wen H. Su

Multiple seam mining and its associated problems are very serious in Southern West Virginia where poor planning or lack of knowledge in seam interaction often results in complete loss of coal properties. Several measures have been proposed to alleviate the interaction problems under various multiple seam conditions, but few of them are specific in terms of mining plan. Two parallel approaches are adopted for this paper. One is field investigation which consists mainly of mine site visits and gathering of data. The other is the two-dimensional finite element simulation of mine workings using the data gathered as input. Two typical cases which represent the past and present multiple seam mining practice in West Virginia were investigated. Much attention is focused on the interaction problems experienced and the important parameters controlling interaction. Several key parameters controlling interaction in multiple seam mining were analyzed. Proper mining plans, by which the interaction problems can be minimized, are proposed for the individual cases after a better understanding of the interaction mechanism was realized through finite element analyses.

Jan 1, 1984

By D. L. Douglas

The ß decomposition of Zr-U-O alloys was studied during an interrupted quench from the a + ß region. Decomposition was more rapid than in binary Zr-U alloys of the same uranium content or qf equivalent ß composition. The rapid transformation has been ascribed to the presence of the primary a phase which provided nucleation sites and which permitted preferential partitioning of oxygen to the a phase and of uranium to the COMMERCLAL heat treatments are designed to produce certain strength and toughness character- istics by controlling the microstructure of an alloy. A desired distribution of microconstituents is achieved in practice by treating an alloy under the correct time-temperature conditions. A knowledge of the phase equilibria in any alloy system is essential in outlining heat treatments, but in addi-

Jan 1, 1961

By W. A. Bruce

THIS paper presents the essentials of a mathematical method of studying the pressure behavior of an oil reservoir as the fluids are withdrawn. Methods are shown whereby the behavior of a reservoir can be used to predict the future relationship between withdrawals and pressure. The oil reservoir is considered as a small part of a large porous continuum, which contains for the most part water. The expansion of this water resulting from a decrease of pressure in the oil zone causes a movement of water that is an important factor in the relationship between fluid withdrawals and reservoir pressure. Examples are given to illustrate the methods of pressure prediction for a circular reservoir containing undersaturated crude, the pressure distribution over a field that has a uniform production rate, the effect of a fault line near a field, the mutual interference of near-by fields, and the perturbing influence of a gas cap. Applications of the analysis to sell-spacing problems are shown.

Jan 1, 1942

By Paul H. Johnson

Chemical mining may be defined as the use of chemicals in extracting metal values from in situ broken or unbroken ores within a mine. The present means for the generation and regeneration of sulfuric acid or sulfuric-ferric sulfate solutions are inadequate for most applications. This report describes a pressure oxidation process for the generation and regeneration of these solutions from pyrites and spent iron sulfate leach liquors. While recent mining developments such as solution injection, caving, and conventional and nuclear blasting, have provided new and better means for the per-colation of leach solutions through rock masses, little has been done to reduce cost and improve the quality of the leach solutions that are required. A leach solution for chemical mining should meet certain requirements. It should be 1) inexpensive on either a small or large tonnage basis, 2) capable of selectively leaching the desired ore minerals contained in a particular ore, 3) of the proper strength or quality to do the job of leaching in an underground environment and 4) amendable to simple and inexpensive metal recovery steps. It is also important that the capital investment be low for the solution generation and; or regeneration plant.

Jan 8, 1965

A 2-year moratorium on accreditation of curricula bearing new designations has been declared by Engineers' Council for Professional Development at its Executive Committee meeting on July 29, 1952. Reason: a more definitive description of what the contents of a curriculum should include to be appropriately designated as "engineering" is needed. This action was brought on by the Committee of Evaluation of the American Society of Engineering Education which had become perturbed over the extension of the name "engineering" to numerous fringe curricula. The 2-year period will permit time for the Committee on Evaluation to study the question and make a recommendation for further action by ECPD. ECPD action also provided that the following curricula should only be given provisional accreditation for one year upon either inspection or reinspection; such provisional accreditation to be extended annually for not more than two successive years pending the report: Engineering Physics, Engineering Mechanics, Geological Engineering, Geophysical Engineering, and Textile Engineering. There are 22 such curricula now accredited.

Jan 1, 1952