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By Mourad Aissa

From our previous work (Gardner, Aissa, and Verghese, 1982) on determining the residence time distribution of ball mi 11s from radiotracer data taken in closed-circuit operation without interruption of the process, it occurred to us that the data taken for this purpose also contained information on the breakage rates of all the sizes present. It is the purpose of the present work to evaluate methods to obtain breakage rates from this data. A numerical solution for the impulse injection and subsequent detection of radiotracer in a closed-circuit linear comminution process is developed and used with typical breakage parameters, residence time distribution, and classifier functions to study and evaluate these methods.

Jan 1, 1984

By W. C. Hagel

In 1952, Hauffe and pfeiffer1,2 reported that parabolic rates of nickel oxidation are decreased by factors of two and four at 1100° and 1000°C, respectively, when Li2O vapor is present. Hauffe 's3 explanation was that monovalent lithium enters the crystal lattice of p-type NiO to decrease cation-vacancy concentration and, hence, diffusion of Ni2+ ions across the growing oxide. After first succeeding in adding lithium directly to molten nickel, the purpose of this investigation was to determine whether alloyed lithium is a more effective oxidation inhibitor than the external vapor. Seven 650-g heats were prepared by melting carbonyl nickel inductively under 1 atm of argon. Various amounts of lithium were added by dropping small chunks into the melt. Only about 10-pct recovery was achieved with the remainder lost by spattering and volatilization. Nominal and actual

Jan 1, 1965

By A. W. Mitchell

Barite occurs as bedded and vein-type deposits in Nevada along a north-northeast trending zone that Parallels the Antler orogenic belt. The Nevada bedded deposits presently supply 85% of domestic barite production, used primarily as a weighting agent in the petroleum drilling industry. The ore bodies are controlled structurally and stratigraphically along regional and local structural breaks in siliceous eugeosynclinal rocks of lower to middle Paleozoic age. Evidence for the origin of the barite includes sedimentary and hydrothermal features, indicating that localization probably took place along fractures in the sea floor.

Jan 1, 1982

By G. K. Burgess

J. W. RICHARDS, South Bethlehem, Pa.-I think my affections are still rather with the radiation pyrometer than the optical pyrometer, for practical use, and I wish that Prof. Burgess would use the two together, under the same conditions, using the optical as his standard, if he prefers. Then, assuming the optical emissivity which he feels is correct for the optical pyrometer, he could calculate the thermal emissivity for use with .the radiation pyrometer. If we could thus get reliable values for the thermal emissivity, we could then use the radiation pyrometer, and would avoid the use of the standard lamp, which has to be frequently calibrated for use in the optical pyrometer. It is very advisable to distinguish carefully between the terms optical emissivity and thermal emissivity. There -is considerable confusion caused by the bare statement that molten iron has an emissivity of so much, meaning by that its optical emissivity, for a light wave of a certain length; whereas what we want in the radiation pyrometer is its total ther-

Jan 4, 1917

By Franklin H. Sharp

The operation of the Magmont Concentrator located on the New Lead Belt of Southeast Missouri is described. Ore characteristics affecting lead-copper-zinc separation are enumerated, and the cur- rent methods of separation are detailed.

Jan 1, 1976

By J. S. Smart

The six countries which make up the European Economic Community-Belgium, France, German Federal Republic, Italy, Luxembourg and The Netherlands-are populated by about 170 million consumers. Their economic abilities and their standard of living have increased at a high rate during the past few years. Consequently, the policies and trade practices adopted by the group will have International repercussions within the nonferrous Industry whether or not other nations are eventually admitted to the group. Considering the hopeful prospects of only a few months ago, it is surprising that we must now face up to the fact that Great Britain and Norway, in particular, will achieve membership status only after prolonged and difficult negotiations, if at all. However, this is but one of many factors that should remind us that the Common Market is yet in its formative stage and has by no means reached maturity.

Jan 6, 1963

By B. Y. Ekber, A. S. Gorbachev

The development of economically effective and safe methods of mining thick coal seams allow considerable coal reserves to be used as an energy resource all over the world.

Jan 1, 1979

The Library of the above-named Societies is open from 9 A.M. to 10 P.M., except on holidays. It contains about 70,000 volumes and 90,000 pamphlets, including sets of technical periodicals and the publications of - scientific and technical societies members of the Institute, with few exceptions, are forced to spend a portion of their time 'in localities isolated from sources of information. To these the Library, through its Library Service Bureau, can render - valuable service through correspondence; letters requesting information will receive especial attention. The Library is prepared to furnish references and photographic copies of articles on mining and metallurgical subjects; to determine the existence of mining maps, and to furnish genera1 information on the geology and mineral resources of all countries. All communications should be made as definite as possible so that the information received may be what is desired and not include collateral matter which may not be of interest. The time spent in searching for such collateral matter will be saved, and the information will be sent more promptly and in more usable shape.

Jan 10, 1916

By C. F. de Mendonca, T. Kater, R. P. de Souza

Since 1976, Cia Vale do Rio Doce (CVRD) has carried out tests to develop a type of pellet made with an organic binder. Peridur is one binder that showed it could be used in industrial plants. Extensive tests were run in CVRD's pilot plant. The results are presented in this paper. The decision was made to carry out an industrial production of 50 ht (55,000 st) of pellets. The results are shown in this paper. No detrimental effects of the Peridur were observed in either the process or in product quality.

Jan 1, 1985

By C. Wegert, L. E. Paulson, S. A. Cooley, R. C. Ellman

The Grand Forks Energy Research Center (GFERC) and Commonwealth Edison of Chicago jointly conducted tests in which 400 tons of subbituminous and lignite coals were dried in a commercial scale dryer, oil sprayed and cooled, then shipped from Pekin, Ill., to Grand Forks, N.D., and stockpiled. Cars containing raw coal and dried coal which had not been sprayed, were also transported for comparative purposes. During transit, observations were made of changes in the coals' moisture content, dust losses, and temperature.

Jan 1, 1977

By C. M. Wayman, S. R. Rauze

It was recently reported' that the initial transformation in (100) iron whiskers grown in the bcc condition can be nucleated on heating in regions of the whisker which are not necessarily the hottest. Although this behavior was observed1 several times, its sporadic nature precluded any documentation other than occasional visual observations during hot-stage optical-microscope heating experiments. The purpose of this communication is to report how, in one instance, the a-y transformation in such a (100) iron whisker was initiated in a region which was clearly at a lower temperature than an adjacent region which did not transform at all.

Jan 1, 1967

By Clark A. Sumner

An apparatus for agglomerating fine particles was developed in 1969 as a joint effort of Stauffer Chemical and O’Brien Industrial Equipment. Commercial sized units were built for agglomerating home dishwashing detergents. Recently, as a result of further pilot development, variation of bed depth and cage configuration has resulted in a means of controlling the amount of internal classification from a minimum, producing small agglomerates, to a maximum, producing compact rounded agglomerates. Little or no external classification of discharged agglomerates is needed. At maximum internal classification the agglomerates roll on a bed of fine particles rather than the shell resulting in increased agglomerate size.

Jan 1, 1977

By Charles J. Speake, Dennis R. Haley, Thomas E. Finch

The tremendous interest in development of surface- mineable coal throughout the western US will bring with it a requirement for many manhours spent in mine planning and equipment selection. One problem in particular that engineers face during the planning stage is that of selecting a dragline with the proper reach capability. Reach, expressed in terms of operating radius and effective spoil radius, can be a major problem when mining deeper than originally planned, and aside from production requirements, the ability of a particular dragline to spoil across a strip is essential. Determination of dragline reach needed for a multiple-seam western coal operation can be simplified by use of an equation derived below that eliminates the need for tedious and repetitive calculations.

Jan 5, 1977

By C. H. Ault, D. D. Carr

Four counties in Indiana- LaPorte, Vigo, Vanderburgh, and Switzerland-have potential for deep underground limestone mining because they are in or near high population areas and have no surface-mineable limestone deposits. The principal markets are Gary-South Bend, Terre Haute, Evansville, and Cincinnati. Mineable seams suitable for aggregate are 120-150 m (400-500 ft) below the surface in LaPorte and Vigo Counties, about 90 m (300 ft) below the surface in Switzerland County, and about 600 m (2,000 ft) below the surface in Vanderburgh County. Some deposits are also suitable for high-purity uses or for cement raw materials, which enhances their potential for exploitation.

Jan 1, 1983

By E. H. Crabtree

Research on the iron ranges begins to bear fruit in big plant construction -Big coppers raise capacity, build at new Arizona, Michigan, Nevada, properties - Hydrometallurgy comes to fore with new uranium ore treatment and the Chemico process for nonferrous metals -

Jan 2, 1953

By S. Ito, Y. Watanabe

In the long range production planning at the Matsumine mine, a management target is to maintain a desired production rate and to keep fluctuations in copper and zinc grades within given allowable limits. A simulation model was developed to find, on a trial and error basis, how feasible and practical the target may be under certain constraints on the underground mining sequence. A number of simulation runs have been made to obtain the most suitable production rate for the long term. In this paper, an outline of the simulation model is described.

Jan 1, 1976

The regular activities of the Institute are financed mainly by income derived from members' dues, from advertising in MINING AND METALLURGY, and from the sale of publications to the public In addition, collateral activities and special projects are financed each year by means of income from endowed funds controlled and administered by the Institute In the aggregate, the amount of these endowments totals more than $830,000 An active effort is being made to increase the endowment funds of the Institute through a standing committee, of which Harvey S Mudd is Chairman, and

Jan 1, 1952

By John V. Beall

W hen the blasts went off on West 11th St., just off 5th Ave. in New York City, James Michaels, editor of Forbes magazine, was in his office a few doors away reviewing color layouts with his production manager. Having once been a reporter, he grabbed his trench coat and dashed for the street to be con- fronted by the demolished townhouse which had been turned into a bomb factory by youths. To Michaels, this shocking episode supplied the exclamation point to thoughts he was formulating that an era had ended and a new one was beginning in the economic and social climate of the U. S. "For twenty years corporate profits, the stock market, middle income pay have gone up and up. . . The illusions of twenty years are in confrontation today with changed needs," he said. "International omnipotence is economically beyond our means, . . The anti-pollution and community renewal people are not nuts in tennis shoes who will go away. . . That corporation presidents can report an increase in earnings every year is an illusion that will be dropped. . . There has been a $200 billion shrink in value of stocks and bonds since Nixon came into office" were some indicators Michaels mentioned.

Jan 1, 1970

By H. Sato, I. Matsuoka, T. Kawai, S. Hasebe

In a limestone mine, a large amount of slime is washed off in order to remove impurities such as clay minerals. A fine sized calcite is, consequently, wasted and freight for carring the slime to reclaim land is expensive. The separation of calcite from the slime has been investigated by the flotation process, using sodium oleate as a collector. A satisfactory flotation of calcite from the slime requires great amounts of sodium oleate, because sodium oleate is consumed by clay minerals. But, the amounts of sodium oleate required are reduced to half by adding suitable amounts of sodium silicate. After rougher and cleaner flotation, the concentrate containing more than 97% calcite is obtained with 70% recovery; thereby the amount of slime to be reclaimed is reduced to 40%.

Jan 1, 1976

By Christopher Haycocks, Lawrence P. Johnson, George M. Neall, James M. Townsend

No method of roof control yet devised has proven to be universally acceptable for the wide range of strata conditions experienced in U. S. coal mines. However, a relatively new innovation, the roof truss, has proven itself capable of preventing roof failures which both conventional and resin bolting could not. Presently, the economics of roof trusses are not favorable when compared to bolting due primarily to drilling and installation procedures, but this is expected to change with improved truss and equipment designs. To realize the full potential of this new method of roof control, design criteria are needed which can optimize the effect of the truss for varying strata conditions.

Jan 6, 1978