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By Stephen D. Antolovich

RECENTLY, much interest has been generated in materials that undergo martensitic phase transformations on straining.')' While it is undoubtedly true that a large amount of ductility can be obtained at rather high strength levels, the question of the general way in which the phase transformation affects the plane strai fracture toughness, as measured by the parameter KIC, has yet to be answered. Let us consider a material that contains a sharp crack as shown in Fig. 1, and is subjected to a tensile stress 00. It is known that the presence of a crack tends to multiply the stress in the area of the crack according to the following equations:3

Jan 1, 1969

By P. Schwed

IN determining the mechanism responsible for sintering, the most direct procedure available is the comparison of the observed time and temperature dependence of the process with the dependence to be expected upon the basis of each conceivable mechanism. This was done by Kuczynskil who, in treating the mechanism of surface diffusion, postulated, in effect, that the concentration gradient of vacancies is different from zero only within the neck. This procedure was recently questioned by Cabrera' who assumed, on the contrary, that diffusion occurs only in the region outside the neck. In the present note, the calculations are performed without restriction on the region of diffusion. To carry out this objective it is first necessary to

Jan 1, 1952

Discussion of the paper of CLARENCE A. WRIGHT, presented at the St. Louis meeting, October, 1917, and printed in Bulletin No. 130, October, 1917, pp. 1565 to 1591. H. A. WHEELER, St. Louis, Mo.-This paper by Mr. Wright is one of the most thorough and exhaustive studies that has been made of the milling practice in the Joplin district. Mr. Wright spent about two years there, in behalf of the U. S. Bureau of Mines and the Missouri Geological Survey, and this paper, which is the result of his work, will, repay careful reading by any student of ore dressing and is invaluable to an operator in that district.

Jan 1, 1918

By Arthur F. Taggart

ENGINEERING is the art of control of men, matter, and energy in timely concert to provide economically the material needs of man. Control requires knowledge of the thing to be controlled and of proven methods of controlling. Knowledge of man comprises understanding of what he is and of his reactions as an individual and in the mass to his surroundings and to other men. Knowledge of matter comprises understanding of its fundamental nature, its methods of combining into multitudes of animate and inanimate forms, the properties of these forms and their various utilities, their sources and availability. Knowledge of energy constitutes knowing what is meant by the term, its various forms and sources, the laws of convertibility, and the methods of transformation and transmission.

Jan 4, 1950

By G. R. St. Pierre, A. Ghosh

In the Si-C-0 system at temperatures of interest in process metallurgy there are four stable condensed phases—silicon, carbon, silica, and silicon carbide (Sic). Silicon melts at 1683oK1 and shows negligible solubility for carbon and oxygen at 1700°K. However, silicon dissolves approximately 1.5 at. pct C at 2500oK.2 Carbon in the form of graphite remains pure and dissolves negligible amount of silicon.' Silica (crysto-balite) melts at 2001°K' and is essentially a stoichio-metric compound. Silicon carbide is a solid and shows negligible deviation from stoichiometry up to approximately 2800oK.2 Besides the condensed phases there is a gas phase

Jan 1, 1970

In May 1952, a total grant of $750 was made for the establishment of a scholar- ship in petroleum engineering for the academic year of 1952-1953, to be ad- ministered by AIME and to be known as the AIME-Socony-Vacuum Scholarship in Petroleum Engineering It will be given In the general field of petroleum engineering The scholar selected must be an undergraduate who is expected to complete academic work during the period of the award In other words, upon completion of the award period, the recipient is expected to be ready to enter industry The establishment of this Scholarship and the selection of the Scholar there under will Impose no ob1igation upon the Scholar or upon Socony- Vacuum with respect to employment The Scholarship is being administered by the Mineral Industry Education Division of the AIME

Jan 1, 1952

By Roshan B. Bhappu, George M. Potter

The chemistry involved in the recovery of gold and silver from natural resources through hydrometallurgical and pyrometallurgical processes is reviewed. Process metallurgy for the cyanidation, activated carbon adsorption, carbon stripping, and electrowinning of gold and silver is discussed. The application of zinc sodium sulfide use for silver recovery from cyanide solutions is covered. Electrooxidation, other oxidation methods and roasting processes for problem ores and concentrates containing organic carbon and impurities such as arsenic, antimony, and tellurides are summarized. The smelting of cathodes, precipitates, and other products, and the various wet and furnace steps in separating dore metal are also reviewed.

Jan 1, 1981

By Richard Pearce

WHILST most of the silver- and copper-bearing veins of Butte have characters somewhat similar, the Gagnon vein has certain rather remarkable features which are not noticed in any of the other mines. The silver-veins proper, as illustrated in the Alice, Lexington, Moulton, and many others, have certain well-known typical characters. Manganese is always present in variable quantities as rhodocrosite or rhodonite, associated with quartz, pyrite, and sphalerite, and with little or no copper. The copper-veins also have certain mineralogical characteristics, which are very similar, or different only in minor points. Chalcocite, chalcopyrite, bornite, enargite, with variable quantities of pyrite, may be said to represent the general mineralogical features of these lodes. It is worth noticing that while the silver-bearing lodes have more or less sphalerite, this mineral is almost entirely

Jan 1, 1888

By John P. Weir

Coal's participation in the domestic energy market depends to a very large extent upon the cost of coal delivered to consumers. Today the principal use of coal in the U.S. is in steam-electric generating stations. Generally, it is the delivered cost per million Btu's that is given the greatest weight in choosing either oil, natural gas or coal as the fuel used in these power plants. There are three major cost components of generating electric energy in steam-electric plants. These expenses expressed in terms of "dollars per kilowatt year" are: (1) operation and maintenance of necessary facilities, (2) fixed charges of necessary capital investment, and (3) fuel. For a modern large plant, the first two items would be approximately as follows:

Jan 9, 1962

By Rodney L. Stone

In past attempts to characterize green and dry iron ore pellets, the authors have found large variations in the results of strength tests performed on closely sized pellets from the same batch. Where bentonite was the binder, such variations in the pellet quality were attributed to the presence of internal flaws and the nonuniform distribution of the binder. Studies have shown that pellet strength is strongly dependent on the degree of "mixedness" of the iron ore concentrate and the bentonite binder. However, before such a relationship can serve as a guide for the development of better mixing techniques and the associated economy of bentonite consumption, more precise knowledge of the bentonite-concentrate mixtures is needed. For example, what is the bentonitc distribution from pellet to pellet and within pellets?

Jan 1, 1970

THE only asbestos mine in the Middle East is on the Island of Cyprus, high in the Trodos Mountain village of Amiandos. The mine is owned by the Tunnel Asbestos Cement Co. Annual output is some 18.000 tons of short fibre in the 4-T. 4-Z, and 5-R grades.

Jan 9, 1953

INTERNATIONAL ENGINEERING CONGRESS This Congress will be held under the auspices of five National Engineering Societies, of whi h the Institute is one. The sessions will be held in 11 sections and the proceedings will be published in 10 volumes of 500 pages each, of which Volume 8 will contain the papers and proceedings on Mining Engineering and Metallurgy. The membership fee of $5 will entitle the holder to the volume of General Proceedings and Index, and, in addition thereto, any other single volume chosen. Other volumes may be subscribed for according to a sliding scale depending upon the number of volumes taken. The Institute will have a meeting in San Francisco during 1915, and it is desirable for our members to join the International Engineering Congress at in early date in order that their support of the enterprise may be given in its early stages, when it is most needed.

Jan 2, 1914

By P. J. Conners, H. Colijn

Belt conveyors have proven themselves for many years as a dependable and low cost method of moving bulk materials at high flow rates. The success of a belt conveyor system greatly depends on the initial loading of the material on the belt. If the material is loaded on the belt at the center, at the same speed and without impact, then about 90% of all belt conveyor problems would disappear. Proper belt loading is primarily determined by the engineering and design of the conveyor transfer point. Some general design criteria required for proper transfer of materials from one conveyor to another are established and discussed. Specific attention is given to loading chutes and skirting.

Jan 1, 1973

By A. H. Lindley, Fraizer M. Stewart

For many years large mining companies were able to finance nearly all of their capital requirements from internally generated funds. However, during the last decade, funds needed for capital expenditures, dividends, and scheduled debt retirement have grown faster than cash flow. As a result the minerals industry has had to rely increasingly on other sources of funds. Getting the capital for new mining projects is a challenge, particularly for smaller companies. New methods of financing and new variations to old methods have been developed and more are needed. Commercial banks are short-term lenders. By policy their loans are limited to low risk loans-those made solely on the borrower's general credit, and secured loans where cash flow is sufficient to provide repayment within a comparatively short term. To maintain liquidity, banks prefer to make loans of less than seven years' term. If a longer loan is needed an insurance company or pension trust may take the long-term part.

Jan 1, 1971

One item of general interest in MINING ENGINEERING Trends, May 1952 gives the wrong impression of the scale of the ilmenite operations in North Carolina It also implies there are known deposits of rutile which "guarantee self-sufficiency for many years" So far as we know this is not true At present, rutile is in such short supply in the United States that the Defense Mineral Authority is encouraging prospecting for new deposits So far none have been found of any consequence and our needs have to be met largely from the deposits near Jacksonville, Fla, and rutile imported from Australia JAY P WOOD VICE-PRESIDENT HUMPHREYS GOLD CORPORATION The reference to self-sufficiency was meant to apply to the ilmenite-bearing sands, not rutile, but improper phrasing failed to make this clear However, the press release that the Glidden Co circulated stated that this deposit of ilmenite was one of the largest in North America -Editor

Jan 1, 1952

By L. D. Muller, C. P. Sayles

When minerals are mined in arid or semiarid areas where water is at a premium, dry processing is a natural route to take for concentrating or classifying the values. Until recently though, dry processing technique were limited by the lack of suitable equipment. With the advent of the pneumatic pinched sluice at Warren Spring Laboratory, Stevenage, Hertfordshire, England, a new tool emerged to fill this gap and it has the potential of providing industry with a high output concentrator or preconcentrator for dry natural ores and secondary materials. The pneumatic pinched sluice gives every indication of fulfilling these requirements with the added advantage that with homogeneous materials-such as crushed limestone or quartzose sands-it may alternatively operate as a high throughput dry classifier or sizing device. An industrial version of the equipment is now being manufactured by Dryflow Separators Ltd., as sole licensee for the National Re- search Development Corporation.

Jan 1, 1971

By Eugene A. Alexandrov

The Minister of Geology of the Soviet Union P.Ya. Antropov, recently visited China and claims that this country occupies one of the foremost places in the world in reserves of tin, tungsten, molybdenum, antimony, iron ore, coal, and phosphates. Occurrences of economic value of chromite, nickel, gold, beryllium, tantalum, niobium, rare earths, and asbestos have also been reported. MINERAL RESOURCES Coal: The inferred reserves of coal are estimated at at 1,500 billion tons. A considerable part of the coal reserves is represented by coking coal, 80% of which is bituminous. Thicknesses of coal seams range up to 150 ft in the principal deposits located in northern and northeastern China. The total output of coal in 1958, 270 million tons, was produced by an army of 20 million people mainly in small mines operated by the agricultural communes. Modern hydraulic mining is applied besides primitive, obsolete methods and equipment

Jan 3, 1960

The separate outputs of Burma and India in 1937 were 274,664,365 gal. valued at £4,474,147 and 75,657,857 gal. valued at £1,030,591, respectively. The corresponding figures for the year 1938 were 263,823,-265 gal. valued at £3,766,810 and 87,082,371 gal. valued at £1,234,563, respectively, which is a slight increase in total quantities but a fall in value for the combined outputs of Burma and India. The appreciable increase from India in 1938 is due to an increase of over 11 million gallons from Attock and a little from Digboi, while the decrease from Burma is due to a fall of nearly 9 million gallons from Yenangyaung, over 3 million gallons from Yenangyat (and Lanywa) and half a million gallons from Minbu (Table 1). The 'amount' of gasoline produced from natural gas during the year 1938 was 10,587,291 gal. in Burma and 496,163 gal. in the Punjab.

Jan 1, 1940

The separate outputs of Burma and India in 1937 were 274,664,365 gal. valued at £4,474,147 and 75,657,857 gal. valued at £1,030,591, respectively. The corresponding figures for the year 1938 were 263,823,-265 gal. valued at £3,766,810 and 87,082,371 gal. valued at £1,234,563, respectively, which is a slight increase in total quantities but a fall in value for the combined outputs of Burma and India. The appreciable increase from India in 1938 is due to an increase of over 11 million gallons from Attock and a little from Digboi, while the decrease from Burma is due to a fall of nearly 9 million gallons from Yenangyaung, over 3 million gallons from Yenangyat (and Lanywa) and half a million gallons from Minbu (Table 1). The 'amount' of gasoline produced from natural gas during the year 1938 was 10,587,291 gal. in Burma and 496,163 gal. in the Punjab.

Jan 1, 1940

By D. Hartley

United States Steel Corp's. Minntac mine is located at Mt. Iron, Minn. on the Mesabi Iron range. The taconite pit is two miles wide, with a maximum depth of 170 ft. Millions of tons of crude ore, waste rock, and surface overburden are handled annually at the mine. All crude ore plus some of the lower-grade rock are rail-hauled; other materials are trucked. Length of rail haul averages 3.5 mi, with a lift of 140 ft. The maximum grade against the load is 1 ½ %. Nine 1200 hp diesel-electric locomotives handle trains of 40-and 50-cu yd side dump cars in crude ore and lower-grade rock service. In addition to this continuous operation, locomotives handle coarse tailings disposal and switching duties on an intermittent basis. All railroad equipment operates under the supervision of a mine control foreman through voice radio communication. The pit foreman also has this frequency available, quickly accommodating any changes in operation that may be required.

Jan 1, 1970