Search Documents

By Ernest Burchard

A RECONNAISSANCE Of the manganese-and chrome-ore deposits of Cuba was made by the writer, as a representative of the U. S. Geological Survey, in company with Mr. Albert Burch of the Bureau of Mines under instructions of the Secretary of the. Interior, in the Spring of 1918. The object of the study was to obtain authentic information for the use of the United States Government as to the location, character, quantity, and availability of the manganese and chrome-ore deposits in Cuba. Accordingly, the work comprised the examination of such deposits as seemed to be of promise, without regard to stage of development, with a view to determination of the quantity and quality of ore likely to become available for shipment during 1918 and 1919, and of the tonnage of ore in reserve. While it was possible to visit most of the deposits that seemed to be of promise, there was not sufficient time to visit all that were brought to our attention, some of which may have merit. Manganese ore is found in Cuba in Oriente, Santa Clara, and Pinar del Rio Provinces, but in Oriente Province only does it occur in large commercial quantities. There, the deposits are in three areas: one north of Santiago de Cuba, one south of Bayamo and Baire, and one on the Caribbean coast between Torquino Peak and Portillo. In Santa Clara Province, a little ore has been found near the Caribbean coast west of Trinidad; and in Pinar del Rio Province, manganiferous material occurs north of the city of Pinar del Rio and farther west near Mendoza. The manganese ores of Cuba occur, principally, in sedimentary rocks, such as limestone, sandstone, and shale, that are in places metamorphosed, and. in beds that originally may have been water-laid tuff

Jan 3, 1919

By Edward W. Parker, Marius R. Campbell

According to the estimates prepared by the U. S. Geological Survey, the area underlain by workable coal-beds in the United States is 496,776 sq. miles. Of this total area, 480 sq. miles contain the entire anthracite coal-fields of Pennsylvania. The bituminous coal-fields are estimated to be contained in areas, aggregating 250,051 sq. miles. The grade of coal between bituminous and lignite, and which is designated by the Geological Survey as " sub-bituminous," is estimated to be contained within areas aggregating 97,636 sq. miles, while the areas containing lignite aggregate 148,609 sq. miles. The coal-fields are divided, for the sake of convenience in classification, into six main provinces, as follows: 1. The Eastern. Province, containing the anthracite coal-fields of Pennsylvania and the bituminous coal-fields of the Appalachian region—namely, those of western Pennsylvania, Ohio, Virginia, West Virginia, Kentucky, Tennessee, Georgia, Ala bama, and small outlying areas in North Carolina. 2. The Interior Province, containing the bituminous coal-producing regions of Michigan, Illinois, Indiana, western Kentucky, Iowa, Kansas, Missouri, Oklahoma, Arkansas, and Texas. 3. The Gulf Province, containing the lignite-areas of Alabama, Mississippi, Louisiana, Arkansas, and Texas. 4. The Northern or Great Plains Province, containing the lignite and sub-bituminous areas of North and South Dakota, eastern Montana, and northeastern Wyoming. 5. The Rocky Mountain Province, containing the bituminous and sub-bituminous areas of western Montana and western Wyoming, Colorado, Utah, and New Mexico. 6. The Pacific Coast Province, containing the areas of Washington, Oregon, and California.

Jan 1, 1910

By John J. Borkert, Carl E. Gerity

In situ mining offers a new and proven method of exploiting sedimentary uranium deposits. The feasibility and economic evaluation of exploiting a uranium reserve by either open pit or underground mining should also include a similar study for in situ mining. This report compares the economics of mining several hypothetical uranium deposits at various depths, grades and reserve sizes by open pit and in situ mining. The evaluation process evolved establishing, where possible, common geological and logistical parameters to both methods of mining. The various assumptions that are unique to either open pit or in situ mining were also drafted, where possible, as equal and common functions to be used in each economic evaluation of the reserve models. After the various parameters were defined, they were programmed to an economic analysis of the various hypothetical uranium deposits by the selected mining method. From the vast array of cost evaluations, total capital and operating cost per pound U308 produced, DCF-ROI, and total net profits before State and Federal taxes were selected as the most meaningful results to compare. From the various geologic parameters used, it was determined that the economic viability of a mining venture is most sensitive to a depth-grade thickness ratio. The three selected evaluation products were plotted against the various depth-grade thickness ratios of the hypothetical uranium deposits. The results of the economic cost analyses show in situ mining generally to be a better method to maximize total net profits and to maximize return on investment.

Jan 1, 1979

By Martin J. Conway

DURING the past year, the intense interest shown by the metallurgical industry in the use of relatively pure oxygen has been evidenced by the number of papers dealing with its application and production. The reason for this interest is apparent when it is realized that, weight for weight, oxygen enters into the formation of steel equally with iron. In the manufacture of steel, approximately one ton of oxygen is required to produce one ton of ingots. Until the recent development of plants capable of producing oxygen at far lower costs than had ever previously been considered possible, the oxygen required for steel manufacture was used as it occurs in air, where it is associated with approximately four times its volume of nitrogen. Because of the diluent nitrogen more than 4 tons of total gaseous material per ton of steel must be handled rather than only approximately one ton required when pure oxygen is used. In addition, provision must be made to handle the large quantity of waste, gases resulting from the process. There are cases where the reduction in gas volume alone can justify the installation of an oxygen plant.

Jan 1, 1947

HENRY M. HOWE, Bedford Hills, N. T. (communication to the Secretary?).-The authors valuable results as to the effects of the air-hardening temperature on high-speed steel may be summed up thus: Influence of Rising Air-Hardening Temperature on. High-Speed Steel Air-hardening microstructure Cutting Properties temperature S Austenite Grain Free Carbide Grains Boundaries Too low Small or Narrow Maximum Too soft undeveloped Intermediate, Well-developed Intermediate Little or even Best correct none Too high Coarse hide, even with Minimum . Weak, brittle, three-rayed crumbling stars Here the suggestion is that as the air-hardening temperature rises it causes two prominent effects, one helpful and the other harmful, the increase of the former exceeding that; of the latter up to a certain point, at which the steel is most useful, and then in turn being outrun by it. The first is the progressive dissolving of the free carbide in the austenite, increasing the stability of the red-hard state. The second is the progressive coarsening of the grains, and thickening of the intergranular cement, developing at last into spandril-like three-rayed stars of the 1,288° specimen. (2,350° F.) of Plate D, thus giving clear proof of incipient fusion, that is of crossing the solidus. This causes intergranular weakness. The individual grains may have great red-hardness, but they do not cohere. They approach the condition of a bag of emery grains.

Jan 6, 1917

By Luis N. Henriquez

One form of encouragement for the small copper mining sector in Chile has been the construction and management of custom mill facilities to process the ore. The paper describes an economic analysis framework for the evaluation of government custom milling opportunities. Feasible mill locations and capacities within a region are selected and the infrastructure and milling costs associated with each combination of location and capacity are assessed. For each combination, the economics of developing and operating known copper deposits in the region is evaluated, and an optimum cut-off grade and mine capacity is selected for the deposits which justify development. Since the total ore supply from mines in the region may exceed a particular custom mill capacity, mine development is scheduled to optimize the economics of the mill facility. Finally, the best custom mill location and capacity is selected on the basis of overall costs and benefits. A copper mining region in northern Chile is used to illustrate the application of the model. A mobile mill approach is examined and compared with the fixed location mill alternatives. Results are analyzed as a function of copper price.

Jan 1, 1977

By R. G. Coyle

This paper describes a model of operating policies in an underground metal mine. The purpose of the model is partly that the problem of controlling a mining operation in the face of shocks from its economic environment is interesting in its own right, and also as an input to a larger research project on policy-making in mining companies. The model includes, mining, development and milling sectors together with cash flow and finances. In particular, it shows how the policies used to control the various sectors in the face of environmental shocks from metal prices and changing state of the system are connected by feedback loops. The use of feedback theory differentiates the model from 'ordinary' simulation and assists in the design of 'robust' policies which always achieve effective control. This model is the first stage of a major project and approximations have been made, simply to get the model going. The purpose of this paper is to show the kind of output this type of model produces, to lay our explicitly what is in the model and above all, to invite contributions from mining people on what the model should show and what should be put into it. We claim no virtues for this model. It is just a research tool so that later models will be more worthwhile and useable in practice.

Jan 1, 1977

By A. E. Bellis

The time effect in reheating certain steels below the critical range is very marked. The increased toughness, shock-resisting power, and machinability of steel subjected to a long, high drawing temperature has been thoroughly demonstrated and is of practical importance, particularly in the manufacture of L'smokeless" rifle-barrel steel. The time effect in tempering is most important when a maximum drawing effect is desired, in which case the highest physical properties as well as ease of machining are important considerations. These are the conditions in drilling a rifle barrel. A hole, 0.30 in. in diameter and 24 in. long for the Springfield rifle, and 30 in. long for the Russian military rifle, has to be drilled in the heat-treated material. This barrel-drilling operation is probably the most difficult one in rifle manufacture, and anyone who has been connected with rifle manufacture knows how seriously production is affected when "hard" or non-uniform steel for barrels is encountered. The importance of high physical properties (tensile strength, toughness and resilience) in a rifle barrel is obvious. The physical properties of two different lots of barrel steel are given below. The first lot, No. 1, gave serious trouble in the drilling operation; the second gave no trouble at all. No. 1 No. 2 Elastic limit, lb. per sq. in.................... 117,450 116,800 Tensile strength, Ib. per sq. in................. 132,500 131,750 Elongation, per cent........................ 16.0 20.0 Reduction of area, per cent................... 42.1 51.0 Impact strength, ft.-lb. per sq. in.............. 450.0 520.0 This difference in machining and physical properties was due entirely to the time of reheating. The first lot was given a reheating time of 30 min., the second lot remained at the reheating temperature 2 hr. Both

Jan 1, 1918

Jan 1, 1933

By Frank C. Roe

Two cogent and ubiquitous facts have supported a constant search by the ore processing industry for better wear resistant materials in equipment. First, designs and types of equipment change or improve continually to meet the economic and physical demands of different and/or leaner ores. Second, practically all equipment is subject to impact and abrasion conditions that probably are more severe and extensive than in any other industry. Development and testing by operators and equipment manufacturers alike, has produced an extensive variety of longer lasting metal alloys, rubber, plastics, ceramics and other materials to improve equipment performance under different specific conditions. The need for diversified materials becomes obvious upon the simple realization that no two beneficiation operations are identical. Among the variables in the handling of ore are: 1. Size and weight of ore particles. 2. Hardness and sharpness of ore particles. 3. Concentration of ore particles in liquid or gas suspension. 4. Velocity and direction of particle impact toward equipment surface. 5. Coefficient of friction between ore particles and equipment surface. 6. Temperature of operation. 7. Chemical environment of operation.

Jan 12, 1967

By John L. Hill

Cutter roof failure is a specific type of ground control problem which frequently results in massive roof failure. It is a common occurrence in coal mines of the Northern Appalachian Coal Basin, causing delays in production and posing a safety hazard to mine personnel. The Bureau of Mines is conducting research on the causes of cutter roof failure to gain a basis from which to prevent its occurrence and to support such roof when failure does occur. Research conducted in a coal mine of central Pennsylvania has revealed a correlation between the occurrence of clastic dikes and formation of cutter roof failure. In-mine mapping of ground conditions showed an increase in roof failure in areas of high frequencies of clastic dikes. Rock pressure monitoring around clastic dikes registered the greatest amount of roof loading near the intersection of dikes with the rib. Load cells measuring horizontal pressure changes in the roof indicated that the greatest pressure changes were occurring perpendicular to entry headings when clastic dikes were present. Analysis of rock pressure monitoring shows that the roof behaved as two cantilever beams when severed by a clastic dike. Additional roof supports such as trusses and cribbing were found to effectively support the roof in areas of clastic dikes and prevent cutter roof failure. However, these methods were only successful when employed shortly after mining.

Jan 1, 1984

By F. J. Tuck

THE Hayden mill of the Ray Mines Division, Kennecott Copper Corporation, is now equipped with two 9 by 12-ft. rod mills having a daily capacity of 6000 tons of coarse-crushing plant product from the mine. These two mills crush a 3/4-in. product to approximately 19 per cent on 14 mesh, with only one pass through the mills. Each rod mill has taken the place of four sets of 42-in. Garfield rolls with their attendant screens, and is making a product for the fine-grinding department comparable to that formerly made by rolls in closed circuit with screens. The rod mills are lined with wave-type liners of white iron, varying in thickness from 2 to 3 in. The shell and end liners last approximately 600 to 700 clays. Manganese-steel lifter bars, 3 5/8 in. thick, are used, spaced about 11 in. apart, and they give a life of 350 to 450 clays. Fig. 1 shows the general design and thickness of the wave-type liners and lifter bars; 1 1/2 -in. liner bolts are used to fasten the lifter bars to the shell. The shell liners are held in place by the tapered lifter bars. A ¾-in. wood hacking is used between the shell and the liners. The rod-mill scoop has removable manganese-steel lips, which last 250 to 300 days. The scoop proper has shown some wear in spots; and these spots have been protected by rubber bolted over them. Water and milk of lime are added to the elevator feeding the mill, but not enough water to cause a pounding of the rods against the shell. Roughly, the water added amounts to 2.5 to 33 per cent of the ore. Addi-tional water is added to the mill discharge to facilitate distribution to the classifier bowls in the fine-grinding department.

Jan 1, 1938

By William Kranz

THE increased service demands on some of the products of the National Malleable Castings Co. prompted it about eight years ago to investigate the electric furnace, both in America and in Europe. The process bad' already been sufficiently developed in Europe to lead us to believe that the electric furnace would most nearly meet our requirements. After further investigation and consultation with the highest authorities on the subject, we decided upon the Heroult type as the simplest and most practicable. In 1910, we built a furnace of this type, of 300 lb. capacity, for experimental purposes, and although it was crudely constructed the quality of the material we were able to make justified the installation of a 6-ton Heroult furnace in 1912. This furnace has three electrodes, 17 in. in diameter, uses three-phase, 60-cycle current, and is equipped with Thury regulators, which give us good regulation and a uniform load on the line even when cold melting. The power factor of the furnace is 94 per cent. Since July, 1912, the furnace has been in continuous operation, producing up to the present time, over 20,000 tons of both carbon and alloy steels of varying analyses and of exceptional quality. Both cold-and hot-metal charges have been used, with a power consumption of about 150 kw-hr. per ton in the case of hot-metal charges and from 500 to 600 kw-hr. per ton in the case of cold charges. The electric energy consumed varies according to the final analysis of the steel and the amount of refining required. Too much cannot be said about the refining possibilities of the electric furnace, for no other method of steel manufacture can compete with the electric in this respect.

Jan 5, 1915

By A. Wahab Khair

This paper presents an analysis of fracture mechanisms in coal subjected to bi-axial state of stresses, indentation of laterally con- fined coal specimen. Coal specimens were loaded to failure by the straight wedge indenters at various lateral confinement pressures. Strain distribution and acoustic emission characteristics of coal specimens under stress were recorded. The influence lines of vertical forces acting on the horizontal straight boundary of the coal specimen for each type of wedge indenter have been established using holographic interferometry technique. The effects of wedge indenter angle, confinement pressure, and coal anisotropy on fracture types, failure modes, and post-failure conditions were studied. The results indicated that combined application of holographic interferometry and acoustic emission monitoring techniques is not only suitable for studying deformability of heterogeneous and microscopically discontinuous material under stress but it also enhances the mode of fracture during the post failure stage.

Jan 1, 1984

By Hsun Hu

Based on Kurdjumoiv-Sachs orientation relationship for the fee bee transformation in metals, the jirzal crystal orientation resulting from successive transformations of bee-fee-bee has been analyzed mathematically. There are 528 different variants; many of ther are crystallograpyically equirvalent. Specific examples show that, for equal probability of all the variants, the principal crystallographic axes [100 ], [110], and [111] of the initial bcc crystal can be transformed into vairous axes in the fina1 crystal However, fur each of these principal crystallographic axes, a continuous range of orientation within certain regions of the unit triangle is completely avoided by the finctl Crystals. For uses of higher indices, the final orientations are more uniformly distributed throughout the unit triangle. Results from the PI-esent analysis are in good agreement with preferred Oientations Observed in a zone-meltecl iron bar. THE allotropic forms of iron are characterized by the unusual fact that at both high and low temperatures a bcc structure is stable, whereas at intermediate temperatures (1400" to 910°C) the metal is fcc. Hence, during cooling from its melting temperature, iron undergoes successive phase transformations ofd—? —a with corresponding changes in the crystal structure of bcc — fcc -bcc. while numerous studies have been made in the past of the 1 — a transformation in iron and in various iron-base alloys, no information is available in the literature as to the mechanism of 6 — l transformation and the lattice orientation relationship between these two phases. Experimental difficulties have apparently prevented researchers from undertaking these studies. The laltice orientation relationship between the parent and the new phases of iron resulting from

Jan 1, 1965

On Wednesday evening, Jan. 27, 1915, were held in the auditorium of the Engineering Societies Building the inaugural exercises of The Engineering Foundation, established by the United Engineering Society. The initial gift to the Foundation of $200,000, made by Ambrose Swasey, Past President of the American Society of Mechanical Engineers, was formally accepted at this time. So far as known this is the first instance of a foundation devoted to engineering purposes. This meeting con-stituted also an appropriate tribute to the generous gift made to the Foundation and gave opportunity for expression of the satisfaction and approval which are felt by engineers everywhere at the establishment of a means of promoting the good of mankind through the work of the engineer along the broadest lines. Gano Dunn, President of the United Engineering Society and Past President of the American Institute of Electrical Engineers, acted as presiding officer, and on the platform were seated representatives of the three societies constituting the United Engineering Society, and of the American Society of Civil Engineers. Members of the four societies and many other friends interested in the profession composed the audience.

Jan 3, 1915

By H. S. Rankin

THIS paper is condensed from several reports by members of the staff of the Minerals Testing Laboratory of the Tennessee Valley Author-ity, on a series of experimental tests in the beneficiation of barite of the Valley area. These experiments were conducted upon a large number of samples taken from several mines in three different districts. The area contains numerous producing deposits, nearly all of which are hampered by the high iron and silica content of the ores. Because of the small difference in specific gravity between the iron oxide and the barite, a gravity separation is generally poor. The removal of the iron thus offers a special problem. Some of the operators have turned to magnetic separation to meet the shipping requirements for less than one per cent iron. The present experiments were conducted to determine the application of decrepitation or flotation in simplifying the concentra-tion of the barite by removing the iron oxide and silica in one operation. Practically all the barite marketed in the area has been as "off-color" crude. The bleaching studies were made to determine the bleach-ability of the ores to alleviate this inferior grading, placing them on the market as bleached barite.

Jan 1, 1938

By N. S. Kenny, A. A. Burr

THE purpose of this note is to present evidence that vacancies, which have been produced by quenching from a high temperature, alter the rate of strain-hardening of an hep single crystal. The majority of investigations of the effects of quenched-in vacancies on the yield stress of metals have been made using fee samples in the form of thin wires. However, there is an inherent disadvantage in using such wires to study the effects of vacancies on the rate of strain-hardening of metals because fee wires begin stage II slip either immediately upon yielding or very shortly thereafter. When stage II slip occurs, very rapid strain hardening also occurs, masking the effects of vacancies on the rate of hardening. In this investigation single crystals of magnesium hep were studied since magnesium has only one slip plane at low temperatures and has, therefore, an extensive easy glide region. In addition, the effect of both static and dynamic recovery on the rate of hardening were eliminated by testing in liquid nitrogen. Both forms of recovery occur in hep metals by dislocation climb, which is a diffusion controlled mechanism and is negligible at liquid nitrogen temperatures. Finally, the dependence of the strain-hardening rate on the crystal orientation was eliminated by using the equations of Schmid and Boas.' Variations in the strain-hardening rate could, therefore, be attributed to the presence of vacancies. Single crystals in the form of rods approximately 5 mm in diam and 6 cm long were grown by a modified Bridgman technique from commercial high-purity magnesium (99.97 pet) supplied by the Dow Chemical

Jan 1, 1962

By W. L. Watts

The existence of petroleum in California has been known for many years. From time immemorial the California Indians used this mineral, in the form of asphaltum, for various purposes. In the early history of the State the Catholic fathers utilized it for roofing their missions and other buildings. It is said that in 1855 or 1856 Andreas Pico distilled petroleum on a small scale for the San Fernando Mission. He obtained his crude oil from Pico canon, near Newhall, in Los Angeles county; and he was probably the first refiner of petroleum in this State. In 1856 a company commenced work at the La Brea ranch, in Los Angeles county, and tried to refine the crude oil. In 1857 an attempt was made to produce illuminating-oil from crude petroleum at Carpenteria, in Santa Barbara county; and there are records of similar attempts in other localities previous to 1860; but none of them were successful. The first scientific report on petroleum in California was made by Prof. B. Silliman, who published his researches in 1865. He spoke favorably of the possibility of obtaining petroleum in remunerative quantities in this State, and gave the results of his experiments in the fractional distillation of California petroleum. The next decade was marked by a considerable oil-excitement in California; and a great many companies mere formed for the purpose of petroleum-mining and for distilling crude oil. In most instances these companies did not meet with success; but it must be remembered that the pioneer oil-miners did not

Jan 1, 1900

By Leon McCulloch

WHEN clean iron and metallic zinc dust, protected from the air, are heated below the melting point of zinc, the iron takes on a coating that has excellent protective value. This coating is a brittle alloy of zinc and iron, and the process is called sherardizing. Although the zinc particles are covered with oxide and cannot touch the iron, an extremely small amount of the zinc vaporizes and the vapor, reaching the iron, alloys with it. Other zinc then vaporizes to replace that which has been removed from the atmosphere. This process continues indefinitely at a decreasing rate, for the coating already formed permits zinc to diffuse through-it to combine with the iron beneath. In this way, the coating grows outward from the surface of the iron, as the bark grows from a tree. The method of growth was clearly seen while sherardizing small cubes of cast iron, at about 450° C., in a small glass-stoppered bottle enclosed in a rotating drum. The dust contained about 3 per cent. iron, which prevented caking, and coatings 1/2 in. thick were grown in a few hours. After a heavy layer had been formed, the cubes were again: treated for a shorter time. The layer last formed was seen to lie next to the iron, instead of at the outer surface, showing that the growth was from the surface of the iron outward. The coatings split at the edges and corners, leaving the iron exposed there. Flakes of graphite from the iron were lifted upward and embedded in the coatings. The composition of sherardized coatings varies from the outer surface inward, as would be expected from the mode of growth. That is, the iron content increases slowly at first, then more rapidly as the iron is approached. At the surface the least amount of iron possible is 6 per cent., as the experiments described below have shown.

Jan 2, 1922