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By T. Fraser, F. F. Giese, R. L. Sutherland

Under a cooperative agreement between United States Bureau of Mines and the Truax-Traer Coal Company, some operating-scale experiments have been made with the cyclone thickener in the preparation plant of the Shamrock No. 1 mine at Kayford, West Virginia. These tests were made with a 14-in. cyclone of the type developed by the Dutch State Mines in Limburg. It was applied experimentally to the thickening of solids in washery water to obtain performance data to show the range of sizes that may be recovered and other operating characteristics that would indicate the field of usefulness of this device in coal preparation practice. This is a progress report only. It covers results obtained in a series of 17 tests of the operation of what has been considered a unit of commercial size operating on suspensions of fine coal mixed with a relatively small amount of free impurities. The underflow material, after further dewatering in centrifuges, is a marketable grade of coal. The coal at Shamrock No. 1 is mined from the No. 2 Gas seam. It is made up essentially of a low ash coal suitable for byproduct use with one or more bands of splint coal of higher ash content suitable for industrial fuel. The washing plant was installed for the two-fold purpose of removing the free impurities incident to mechanized mining and to separate the run of mine coal into the two types. To accomplish these results it is necessary to make a separation at a specific gravity of about 1.4 to recover the byproduct coal and to separate the splint coal from refuse at a higher gravity. The coarse coal section of the washing plant was put into service about 10 months before the fine coal section was completed. Inadequate screening capacity in the raw coal preparation plant resulted in a portion of the fine coal being fed to the jigs. No provision for preliminary dedusting of the raw coal feed was incorporated in the design. Under the conditions in the initial operating period, separation at the desired lower gravity was not realized, apparently because of the presence of an excessive amount of fine solids in suspension in the wash water. Difficulty in wetting the fine coal may also have been a contributing factor. Additional facilities for the removal of the fine solids from the wash water was indicated. Information then available on the Driessen cone for this purpose was studied and a cooperative agreement with the Bureau of Mines for experimental work with a unit of standard size as developed by the Dutch State Mines was arranged. During the time required for construction of the cone it was found the addition of a small amount of wetting

Jan 1, 1950

By Donald C. Myntti

INTRODUCTION A major segment in a successful heavy equipment maintenance and repair program is the provision of well-laid out and well-equipped shop and service facilities The facilities described here will be those required for a large, high tonnage hard rock open pit mine utilizing rotary drills, shovels, haulage trucks, support equipment, and service trucks. The term support equipment covers the equipment required to support the drill, shovel, and truck operations, these are crawler tractors, road graders, front-end loaders, water trucks, rollers, rubber-tired tractors, etc. Service trucks are the automotive type consisting of rubber-tired over-the- road equipment. The primary structures generally involved in the total maintenance effort are as follows. (1) the main shop with an attached warehouse (the structure could also house the tire and lube shops plus the equipment cleaning stalls), (2) a service station with bulk petroleum product storage tanks, (3) a heating plant, (4) a security station (lf this is a corporate requirement), (5) operating department and employee assembly buildings, and (6) an electrical substation. Under certain conditions, many of these facilities with the exception of the substation could be combined In one or several structures. This arrangement could have a great advantage especially in areas where the heating of the structures is extremely critical.

Jan 1, 1979

By D. C. Hilty, W. Crafts

J. Chipman—It has been my privilege to discuss this work with the authors on several occasions and to observe at first hand the experimental methods employed. I wish, therefore, to emphasize certain points which they have mentioned only briefly with regard to the experimental techniques. The rotating induction furnace as here employed interposes liquid metal between slag and refractory thus preventing the two nonmetallic parts of the system from reaching equilibrium with one another. It is therefore impossible for the metallic phase to be completely in equilibrium with both the slag and the crucible. The metal also acts as a partially permeable membrane allowing certain components, including oxygen, to diffuse from slag to crucible. This transfer results in building up on the face of the crucible a layer of material whose composition is in part dependent on that of the bath. Reactions between the layer and the solid refractory are slow, as evidenced by the rather good life of the crucible. Hence it seems probable that the layer is more nearly in equilibrium with the metal than with the underlying crucible material and that, once it is established under a bath of a given composition, its further reactions with that bath are slow. Additions to slag or bath may be followed by changes in the layer; and time must be allowed for virtual completion of such changes, before it can be assumed that slag and metal are in equilibrium. We may judge from the results reported that, in general, this was the case and that the data represent at least quite close approximations to slag-metal equilibrium. Data on deoxidation and on oxygen solubility are no better than the analytical methods employed. The vacuum fusion method as used by the authors seems entirely adequate for the samples analyzed. I have had frequent occasion to compare results with their laboratory, always with very satisfactory agreement. The determination of aluminum at very low concentrations is perhaps an even more difficult procedure. Here also the colorimetric method used has been worked out with great care and is undoubtedly the most dependable method available. The discrepancy between observed and calculated deoxidation or solubility lines is not to be explained as the result of experimental errors, either in the sampling or analysis of the metal. Nor is it to be blamed upon inaccuracies in the several kinds of indirect data upon which the calculated results were based. It is true that both the observed and the calculated lines admit of some uncertainty as to their exact locations, but the uncertainties are small compared to the wide gap which separates the two lines. The authors have pointed out the real cause of the discrepancy. In all of their experiments the solid phase was not Al2O3 but a mixed oxide containing iron and aluminum. This suggests an extension of the calculated values to include equilibrium with the spinel FeO . A12O3. The free energies of FeO and A12O3 are known, that of the spinel is not. However, it cannot differ greatly from that of its component oxides for even in the more stable spinel, chromite, the free energy of formation from the oxides is less than 10,000 cal. For purposes of calculation we shall call this free energy X and solve for values of X lying between zero and 10,000 cal. The other data required are taken from the forthcoming revision of "Basic Open Hearth Steelmaking" and are given in the following equations in which underlined symbols indicate elements dissolved in liquid steel and the standard concentrations are 1 pct. ?F° at 1600°C, cal ?LA = 2 Al + 3 O; + 107,200 FeO = Fe + 0; + 5,460 FeO + A12O3 = Fe + 2A1 + 4 0; + 112,660 — X The corresponding equilibrium concentrations are shown in fig. 21. The line marked A12O3 corresponds to the first equation, those marked FeO . AL2O3 correspond to the last, with X = 0, 5000 and 10,000 cal, respectively. The two upper lines represent the data of Hilty and Crafts and of Wentrup and Hieber. The points are the observations of Hilty and Crafts in the presence of 0.50 pct Mn.

Jan 1, 1951

By P. Bardzil, J. Gurland

An experimental study of the variation of transverse-rupture strength with composition Anexperimentaland grain studysize has shown that the strength reaches a maximum for values of the mean free path between carbide particles of 0.3 to 0.6 microns. The fracture oforiginates in and proceeds through the carbide grains mainly. Impact strength and hardness also were recorded. MOST of the physical properties of sintered carbides vary linearly with composition. The transverse-rupture strength, however, shows a unique behavior. As the amount of binder metal is varied from 6 to 25 pct by weight, the strength at first increases; then, between 15 and 20 pct Co, it reaches a maximum of nearly 400,000 psi, and finally decreases with further additions of binder metal. This behavior of the transverse-rupture strength has been reported, among others, by Englel and Sandford and Trent.' The significance of these observations has not been discussed in the literature. That it may be of more than specific importance is indicated by the very similar variation of strength with composition encountered in other systems sintered in the presence of a liquid phase, such as Tic-Ni3 and Fe-Cu.' Experimental Details All compacts were prepared and sintered according to normal industrial practice. The average diameter of WC grains and the mean free path between grains were measured on metallographically prepared samples by a method of linear and planar analysis sing the relations where d is the average diameter of dispersed grains; Nl is the number of noncontiguous grains intersected on a metallographic plane by a line of unit length; N, is the number of noncontiguous grains per unit area; P is the mean free path between grains of dispersed phase; and f is the volume fraction of dispersed phase. Approximately 1000 grains were counted on each sample. For each composition d2 was plotted against P, the resulting straight lines serving as a check on the measurements. The distribution curves of the WC powders of different average diameters were homologous, and no attempt was made to influence the grain size by blending powders, adjusting the sintering conditions, or otherwise altering the particle size distribution. Densities were measured by differential weighings in air and water. The degree of densification did not vary consistently with either composition or grain size. The density is influenced by slight amounts of impurities, specifically by 0.1 to 0.2 pct Fe which enters the powders during ball milling. As an illus- -tration of the experimental variations, a number of measured densities are listed in Table I. They are expressed in percentage of theoretical density, as calculated from the published X-ray densities of WC and Co.' For the purpose of determining the transverse-rupture strength, rectangular test specimens (3/16x 3/8x3/4 in.) were broken by loading at the center of a 9/16 in. span. The average strength of five or more samples is reported for each composition and grain size. The compacts were ground on two parallel surfaces only. The load was applied at an average rate of 6,800 psi per sec. Since the elongation after fracture of the alloys is very small, it was assumed that the compacts deform elastically to failure and the fracture stress was calculated by the conventional beam formula. The data for one alloy are presented in Table II as an example of the results and scattering ranges encountered. The precision of the test, as measured by the average difference between duplicates, is of the order of 15,000 psi. The results are strictly comparable only to compacts prepared and tested in the manner described and of similar chemical composition and grain size characteristics. Unnotched Charpy specimens were used for impact testing. Each point represents the average of 3 to 20 samples, the larger number being used in an attempt to determine the influence of grain size. Considerable scatter was encountered, the range from lowest to highest value often amounting to 30 pct of the impact strength. The hardness is reported as a Ra reading, using a 60 kg load with diamond brale indenter. Compositions are given in weight percent.

Jan 1, 1956

By Charles A. Lindberg

It will be generally agreed that the most important accessory to a rail haul operation is the railroad type locomotive crane. The oldest and still most common type is the steam crane, a self-contained steam power plant, coal fired, complete with boom and hoisting machinery and mechanical drive capable of propelling the unit on its own power at speeds up to 15 mph on the level, and hauling, if necessary, a car for transport of the objects being handled. Usually, for greater mobility and safety, this crane and flatcar are moved around the pit by a switcher locomotive. Crane capacities range from 25 to 40 tons, these loads being handled with the shortest radius of boom and with outrigger. Boom lengths are 55 to 60 ft long, usually with heavy lift main blocks at 40 ft boom lengths. Lifting capacities with booms at maximum radius are approximately 20 % of maximum rating. Free capacities, namely without outriggers, range from 65 (at minimum radius) to 55% (at maximum radius) of the above capacity values.

Jan 3, 1950

By R. L. Huntington, D. T. MacRoberts, Charles R. Hetherington

SINCE the equation of continuity governing transient flow of gases through porous media cannot be integrated mathematically into a simple usable expression free from series terms, empirical and approximate equations have been advanced relating cumulative production and future production rates from gas reservoirs with time. In order to check the accuracy of these empirical equations and to obtain an insight into the initial conditions pertinent to the solution of the fundamental equation of continuity, experimental work has been conducted on a vertical 2-in. tube, 91.6 ft. high, packed with unconsolidated Wilcox sand. The results presented in graphical form show the accuracy of the approximate relations. Data from unsteady-flow runs on the 2-in. experimental tube are presented graphically, and are applied to obtain an equation for this specific case, and are offered as an aid in future investigations of this basic equation. The close agreement between equations calculated for steady-state flow and the experiments indicates that the decline of actual gas reservoirs may be treated by an application of these equations without serious error.

Jan 1, 1942

By C. G. Dunn, K. T. Aust

SEVERAL studies1-10 have reported a type of grain boundary migration which occurs when a strained grain grows into an adjacent deformed grain during annealing. Beck and Sperry called this phenomenon strain-induced grain boundary migration, since the observed boundary movement, which takes place in a direction away from the center of curvature, is apparently motivated by the excess free energy of strain hardening. However, little information has been obtained on the detailed structural changes accompanying such grain boundary motion. The problem of driving force for strain-induced boundary migration was considered by Dunn and Daniels,' who used bent bicrystals of Si-Fe. They demonstrated that two grains of differing energy, in the form of subboundaries, behaved according to the concept that the low-energy grain would grow at the expense of the high-energy grain. Beck" reported experiments of Sperry for high-purity aluminum, which indicated that generally the particular grain of a pair which work-hardened more was invaded. The measure of work hardening here was

Jan 1, 1958

By AIME AIME

MEXICO embraces one of the great metal and petroleum producing provinces of the world. In this respect its history dates back to the overthrow of the Aztec empire by a Spanish force under Hernando Cortes between 1519 and 1.521. Even before then, its richness in silver and other minerals was not unknown. But it was a treasure house for the Spanish conquerors until the country became independent in 1821. It has been computed that in the 400 years following 1521, Mexico yielded 1.55,000 metric tons of silver, worth $3,000,000,000, two-thirds of the entire world production. In 1935 the country accounted for 36 per cent of the world's silver output, 14 per cent of its antimony (in 1934), 13 per cent of its lead, 3 per cent of its zinc and copper, and 21/2 per cent of its petroleum. Contrary to the impression of some, its gold output is now comparatively small, though important in the past. Its oil, as well, formerly hulked much larger than now, in 1921 being one-fourth of the world output.

Jan 1, 1936

By Stewart, J. B.

THE property at which this work was done consists of a large deposit of potash salts occurring in massive beds of rock salt, overlain by 600 ft. of salt-impregnated shales and marls. It is in the Province of Cataluiia, Spain, about 45 miles from the railway station of Mauresa and about a mile south of Suria. In addition to sinking the shaft, the program of construction work laid out by the European owners (not Spaniards) included a single-track narrow-gage railroad from Mauresa to the mine; one large office building and several large shop buildings, all of brick and concrete with steel truss roofs; two extensive benches for the future recovery plant; and a large village of stone dwellings for employees. The pay-roll showed approximately 1200 to 1500 men employed. After two years' operation, ending early in the autumn of 1920, the shaft had been sunk 325 ft. and still had an equal distance to go to reach the potash; all tunnels for the railroad were done and the road-bed $0 per cent completed; only a little more than the foundations were completed for all the large buildings, and the excavations of the benches were about 75 per cent done-while only a fair start had been made upon the employees' village. This was the state of affairs when the European owners decided to offer this property under a one-year option to an American syndicate, providing that they agreed to carry on the entire building program and to sink the shaft as fast as was consistent with the quality of work which they demanded, for they wished the shaft to endure at least 200 years.

Jan 1, 1926

By A. L. Mular

lnput energy-size modulus relation at small reduc-tion ratios is expressed by Et = (M, -Mt) k;. In some cases 13 is close to Schuhmann's distribution modulus a in value. Experimental results in conjunc-tion with the equation demonstrate the fact that energy input which produced fracture is not expended on unbroken starting material inside the mill at any time. Recently, schuhmann1 derived the Charles equation2 using the postulate that complex com-minution operations can be considered as a summa- tion of many comminution events. The fragments resulting from each event are assumed to follow the Gaudin-Schuhmamn distribution. In his derivation, Schuhmann implies that the size distribution of the total mass of a material is determined by the fraction of that mass actually subjected to comminution. Consider a feed to contain a volume, Vo, of uni- formly sized homogeneous material. After t seconds of grinding, let the volume of broken material be Vo - Vt where Vt is the volume of starting material not yet broken. The size distribution of the broken material is given by: where V is the cumulative volume less than size X, and k, is the size modulus of the broken material at time t. The distribution for the total volume at this

Jan 1, 1962

By William M. Shepard

The Tintic mining districts of central Utah com- prise one of the major silver-lead producing areas in the United States. Ore valued at nearly $450 million has been produced from these districts since the initial discoveries, in 1869, of veins cutting the Silver City monzonite stock. Subsequent production from the famous manto-type "ore runs", which characterize the Main Tintic district, was followed during the past 40 years by discovery of the blind orebodies of the East Tintic district, including the famous Tintic Standard mine and the most recent discovery, the Burgin mine, currently being brought to full production by Kennecott Copper. The occurrence of blind orebodies of exceptional size and grade in both the Main and East Tintic districts has made this area a field laboratory of major importance for the study of geochemical dispersion halos and alteration features associated with known ore, and has led to the discovery of additional concealed orebodies. The larger share of the basic data-gathering and interpretation has been done by members of the U.S. Geological Survey who have been studying the Tintic mining areas since before the turn of the century. These studies have been supplemented and expanded by the geological staffs of the local operating mining companies, by exploration geologists and by students.

Jan 4, 1966

By F. S. Crawford

IRON and copper are mined in the Lake Superior district. The iron mines of the district have the best safety record for that industry in the country as a whole, while the copper mines of the district rank second in two of the four years recorded (Table 1). In Utah copper comes mainly from open-pit mines, which enables that state to lead easily in safety. All of the Michigan production comes from deep under-ground workings. About 60 per cent of the iron miners in St. Louis County, Minnesota, are employed at open-pit mines; this favorably affects the combined open-pit and underground accident-frequency rate, as this county pro-vides most of the Minnesota-mined iron ore. In Michigan, however, there are few open-pit mines, the bulk of the production coming from underground mines, while all of the Wisconsin production, just across the state line from Michigan, is from underground mines. In spite of the fact that fewer mines in Michigan use the safer open-pit method, the iron-mining industry of that state maintained a consistently low record from 1931 to 1934; however, it was many points behind its nearest com petitor, Minnesota, with its much greater production from open-pit mines.

Jan 1, 1939

By Arthur L. Walker

In June, 1893, while I was with the Old Dominion Copper Co. at Globe, Ariz., I received an offer to take charge, as manager, of the Baltimore Electric? Refining Co. which had recently built a plant at Baltimore, Md., having a capacity of about 1200 tons of electrolytic copper per month, using the Hayden series system. This was a very large output, for in those days the plants were small and the art was in its infancy. At the beginning of 1893 there were 11 electrolytic refineries in the United States, most of them using the multiple system. The Hayden series system was used at Baltimore and Bridgeport and the Smith series system was in operation at the Electrolytic Copper Co. at Ansonia, COM., and at the Pennsylvania Salt Co. at Philadelphia. In the latter system the plates were placed in a horizontal position, but the operating difficulties were so numerous it was soon discarded. The total production of these 11 plants in 1892 was very small; I have not been able to discover reliable figures of production. There were about thirty electrolytic copper refineries in the world that year, according to Titus Ulke, and the entire production of these

Jan 1, 1932

By C. A. Heiland

MEASUREMENTS of gravity with gravimeters have come into increased use in this country and abroad in the past five years. Probably 100 to 125 gravimeter parties are working in the United States alone. In oil exploration, gravimeter methods have relegated the gravity pendulum definitely to second place, if not third, and now closely rival and possibly surpass the torsion balance in many applications. Gravimeters have lately been applied in mining, although it is doubtful whether they will ever replace electrical or magnetic methods in this work. Notwithstanding the widespread application of gravimeters, there has been no article covering the entire field in the domestic or foreign literature. The purpose of this paper is to meet the demand for com-prehensive engineering information on the subject. The working principles of a number of gravimeters will be, illustrated and treated in relation to the action of corresponding seismometers and astatization methods. The mathematical discussion of theory has been confined to the most necessary fundamentals and been given in as ele-mentary form as possible. A description of calibration methods con-stitutes the last part of the paper. The symbols shown at the top of page 2 will be used in equations throughout the paper.

Jan 1, 1939

By J. R. Linney

THE Eastern magnetite industry has not failed in its contribution to the war program during the past year. Man-power shortage was the critical problem in maintaining production and for the last half of the year, owing to lack of man power, it was necessary for some mines to change from seven to six days per week schedule. At Cornwall, Pa., the mine operated by the Bethlehem Steel Co. produced approximately 2,000,000 tons of crude ore and 1,200,000 tons of iron ore concentrates, a decrease of about 10 per-cent compared with the previous year. Railroad haulage in the open-pit at this mine was discontinued, being replaced by Mack trucks of approximately 30 tons' capacity. At the Mt. Hope mine in New Jersey, the Warren Foundry and Pipe Corp. produced about 195,000 long tons of crude ore obtaining 70.000 long tons of lump ore and 35,800 long tons of concentrates. An additional 24,500 long tons of concentrates was produced from a stock pile of 47.000 long tons of crude ore accumulated during the latter half of 1943, following the fire in their old dry mill. All of this material was handled through their Brown

Jan 1, 1945

By Arthur A. Center

WAR demand- motivated developments in the zinc industry during 1942. Stocks of Prime Western were built up and High-Grade remained tight. The Prince The Prime Western stocks are expected to be cut down and the demand for High-Grade more easily filled as the Depue reflux plant of the New Jersery Zinc Co. increases - production. Subistition of steel for brass in artillery shell cases will have a considerable effect on the zinc situation of the country one estimate of the saving in zinc in 1943 by this substitution being a little under 100,000 ton, of metal. The metal saved will, of course be High-Grade. If the substitution occurs, the present tight situation in High-Grade may be entirely relieved as new production comes on the market and zinc may find itself approaching a situation as comfortable as that of lead provided the supply of zinc-hearing raw materials is sufficient to keep all reduction plants tip to capacity production. The premium price of the per pound of zinc over set quotas which went into effect early in 1942, helped to bring about the new lead-slag-fuming plant and other new sources of raw materials.

Jan 1, 1943

By Charles C. Goddard

Since discovery of silver-gold lode deposits in 1864, the Butte district has produced more than $2.25 billion worth of copper, zinc, manganese, silver, and gold, an unprecedented value in the mining world. Exhaustion of the gold placer deposits along Silver Bow Creek, southwest of Butte, forced the early-day placer miners to turn their attention to the bold out- crops of the many veins exposed on the hillsides above the placer diggings. These outcrops bore silver and gold, and enough so that many lode claims were located. Such famous silver mines as the Alice, Moulton, Magna Carta, Nettie, and Blue Bird were developed. These and many smaller operations contributed to making Montana the leading silver-producing state in the 1880's. As depth was gained in the silver mines in certain parts of the district, occurrence of zinc minerals became troublesome. Zinc was not recoverable at the time, and in the chloridizing, roasting, and amalgamation of the ores, silver and gold recovery was greatly reduced. A period of active silver mining continued until 1892, when a decline in the price of silver brought the silver mining period to a close. Elsewhere in the district it was discovered that while some of the veins contained silver ores in the oxidized portions, the predominant minerals that were deeper were copper-bearing. Marcus Daly exposed rich copper ore on the 300 level of the Anaconda mine in 1891, and mining in the district disclosed that copper was destined to be developed in abundance. Early copper ore shipments were made to Swansea, Wales.

Jan 3, 1959

By H. B. Northrup

Mineral Industries Extension instruction was pioneered by The Pennsylvania State Colleges Extension work was organized in 1893 and constituted what is believed to be the first vocational adult educational effort in that field in America. From 1894 to 1899, twenty-seven extension bulletins were printed and distributed free for the benefit of classes in the coal-mining industry and the records show that free lectures wore delivered by a corps of teachers of the mining department of the College "to the mining employees at their customary lace of assembly upon matters of interest to them in their occupation." In 1899, the State Legislature reduced the appropriation to the College and therefore the extension pamphlets and lectures were discontinued. Several sporadic attempts were made to resume the extension services in mining through industrial grants for travel and publications, and through voluntary contributions by members of the resident staff. The work. consisted mainly of lectures and demonstrations and served the purpose of creating the desire for more training and information of a more formal character. In 1928, the nave of the school was changed, by trustee action, from School of Mines and Metallurgy to the School of Mineral Industries and the working structure of the school was organized under the three functional collaborating headings: Resident Instruction, Correspondence and Extension Instruction, and Mineral Industries Research. The three functional bodies are separate, yet interdependent. The Federal Smith-Hughes law, passed in 1917, made Federal and State funds available for vocational educational work. Mining extension was revived in 1919 and the College employed one full-time extension professor to reorganize the work and instruct the classes. In 1923, the State Department of Mines and the State Department of Public Instruction entered into, a formal agreement with the School of Mineral Industries to assist the College in its extension program.. Classes were organized to study the State mining laws and State Department of Mines' previous examination questions and answers, in preparation for coming state examinations for certification of competency as underground officials. Mimeographed lesson material was used at first, and in 1947 and 1929 mining instruction and mining teacher-training lessons were printed. In 1931, the extension activities of the school were placed on an organized basis compatible with the newly formed school organization and a director was appointed to tale full charge of the work. During that year, at a conference in Harrisburg, an agreement was consummated between the State Departments of Public. Instruction, Mines, Labor and. Industry, and the College whereby extension classes in the field of the, mineral industries could be organized by the College, throughout the State, under "public supervision and. control," in close cooperation with the State Department.

Jan 1, 1941

By E. J. KENNEDY

THE 142D MEETING of the Institute is rapidly shaping up with splendid prospects of a strong technical program and the lighter side of this annual occasion amply provided for. The date is February 20 to 23. The technical sessions will be held in the Engineering Societies building; the smoker-dinner, the informal dance, and the annual reception and dinner, at the Commodore Hotel, Monday, Tuesday and Wednesday respectively. The news to date on the technical side is as follows: Mining Methods-Subsidence The Mining Methods Committee has prepared an interesting program which will be divided into two sessions to be held early in the week. At the first there will be papers on mining methods and development, including a description of the "Sinking and Equipment of No. 2 Shaft at Minas de Matahambre," by Dudley D. Homer and R. H. Cromwell. They describe in considerable detail the equipment used and the practice followed in sinking this important shaft, giving detailed costs and performance figures. Hoist¬ing ?arrangements and mining practice at the "Red Ore Mines of the Woodward Iron Co. at Bessemer, Ala.," are described by Tenny C. DeSollar, superintendent of mines, in a second paper. At this session of the Mining Methods Committee, H. M. Roche and R. E. Crockett, of the Committee on Eastern Magnetite Mining and Milling Methods, will present their paper, "Iron Ore Mining at the Scrub Oak Mine." This mine is in the highlands of New Jersey about 40 miles west of New York City. Prof. Robert K. Warner of Yale University will present a paper on "The Selection of a Mining System," which should have an interesting discussion. Pierre R. Hines, of Portland, Ore., will present, with stereopticon slides, his paper on "The Owyhee Tunnels, U. S. Reclamation Project, Owyhee, Oregon," describing one of the recent irrigation undertakings.

Jan 1, 1933

By H. F. Kendall, J. H. Ffolliott

MANY papers and reports have been devoted to the geology and ore deposits of the Ducktown district, Tennessee, especially the complete report by W. H. Emmons and F. B. Laney, published as Professional Paper 139, by the U. S. Geological Survey. The present paper discusses the work of the geological organization of the Tennessee Copper Co., which is based on the field work of the above paper and the consulting work of W. H. Emmons. The Ducktown basin lies in the southeastern corner of Tennessee and extends a short distance into Georgia and North Carolina. All productive mines are contained in an area of 15 sq. mi. in the center of this basin, which is an undulating plateau at an elevation of 1650 to 1800 ft. above sea level. It is surrounded by the relatively high mountains of the southern Appalachian region. The rocks are of early Cambrian age. Deposition of the ores probably took place during the latter part of the Paleozoic era. The ore deposits are rudely tabular to lens-shaped bodies of massive sulfide, varying from a few feet to over 200 ft. in width. In general they all strike northeast and dip southeast at angles from 45° to 70°. Locally, where affected by folding and faulting, the variations in dip may be even greater. The lodes usually are parallel at distances of from one-half to one mile measured normal to the strike. The deposits are a replacement of a fairly continuous bed or a series of disconnected limestone lenses, highly folded and somewhat faulted, which probably represent the same stratigraphic horizon.

Jan 1, 1933