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By T. W. Healy, D. R. Dixon

The mechanism of activation of ZnS by metal ions and the subsequent flotation induced by xanthate has been considered as a surface redox reaction. By ultraviolet (UV) irradiation of ZnS suspensions, the normally inert ZnS is caused to react with xanthate in the absence of activator. By similar UV irradiation, the rate of adsorption-exchange of activator ions at the ZnS-H2O interface is also increased. Mechanisms of these reactions are proposed and compared to current electrochemical and semiconducting models of sulfide flotation.

Jan 1, 1976

By G. A. Vissac

The drying of fine coal involves special techniques, which are discussed and analyzed. Types of dryers employing these techniques are described. Calculations are presented for new methods of deal ing with the entrained dust that is always present in fine coal drying operations.

Jan 10, 1953

By R. O. Burt

The economics of recovering slimes by gravity concentration, except in a few highly specialized cases, was hampered by the lack of suit- able high capacity equipment. However, in the last decade increasing cost of power and reagents, coupled with the development of high capacity units, has led to a reappraisal of the benefits of slime gravity concentration. This paper seeks to analyze the merits of gravity concentration, and the constraints placed upon it by the laws of motion. It traces the recent developments of unit processes, and their application to a wide range of minerals. The economics of gravity concentration are also discussed.

Jan 1, 1980

By Andrew Balint, Peter Cammack

When coal is irradiated by the X-rays emitted from a plutonium 238 isotope, the radiation absorbed by elements of low atomic number (carbon and hydrogen) is lower than that absorbed by elements of high atomic number (silicon, aluminium, iron) which form the ash in coal. The differences are reproducible and readily measurable, and this paper describes how this technique is used to determine the ash content of coal and to optimize measurement accuracy. Uses of the output signal are given with an example of a simple control circuit, and the advantages of instantaneous ash measurement are highlighted in terms of operational convenience and profit.

Jan 1, 1977

By Nicholas J. Grant, John S. Benjamin, Bill C. Giessen

In the course of a study of hard particle-duc tile binder composite alloys, interest arose in the nature of the products of the reaction between the inter metallic compound NiAl and the binder niobium. No published information was then available. A program to

Jan 1, 1967

Jan 1, 1880

By Charles A. Ashburner

DURING the early part of August, 1880, I was directed by Prof. J. P. Lesley, State Geologist, to assume charge of the geology and mapping. of the Second Geological Survey of the anthracite codfields. I visited the region uninaumbered by any instructions other than this,—that I should submit a plan for making the sur-

Jan 1, 1881

By E. A. Hartsook

Since World War II we have all been treated to repeated public and private evaluation of the population explosion. Improvements in medicine and agriculture have brought greater life expectancy and a decreasing infant mortality rate. This has brought boom conditions to some areas-and pressures everywhere for the amenities of life: a little elbow room, a tree or a pot of flowers, space to hike or swim with some freedom have all become premium commodities. With this wish for privacy and attractive surroundings, people are being forced to move to once sparsely populated areas. Suburbs expand or sprawl, depending on the point of view. New country is touched by a freeway and houses and stores spring up overnight. Entire new cities are born to meet the increasing mobility of industry and its work force.

Jan 6, 1965

By C. L. Dake

RESIDUAL deposits occur both as products of weathering and as products of hydrothermal decay. PRODUCTS OF WEATHERING That climatic conditions affect greatly both the rate and the results of weathering, is shown. in temperate, polar, arid, and tropical regions, each of which will be considered separately. Weathering under Temperate Climates The decomposition of any rock is accomplished by the removal of the more soluble bases, and a concentration of the relatively insoluble oxides of iron, aluminum, and silicon. By reason of its some-what greater solubility, silica is much more subject to removal than iron and alumina. The two important residual end products of weathering are sands and clays, the former consisting essentially of quartz, and the latter of kaolin and limonite.1

Jan 5, 1915

Jan 3, 1951

By Dorsey Hager

One of the most interesting fields in North America was discovered, early in 1922, near the towns of Sunburst and Kevin, Toole County, Mont. This field produces oil from the Jurassic beds, which heretofore have been of but little importance as oil producers, and promses to be the

Jan 1, 1923

By B. H. Sage

ATTEMPTS have been made to predict the volumetric and phase behavior of naturally occurring hydrocarbon mix-tures1-5 but these methods have not been extended to the higher pressures and tem-peratures that are currently encountered in some producing formations. Furthermore, the methods of prediction at present avail-able have not been tested in a sufficient number of cases to ensure their applica-bility to all naturally occurring hydrocar-bon mixtures, even at the lower pressures and temperatures. For these reasons the behavior of a number of hydrocarbon mix-tures from a field in which the subsurface pressures are above 4500 lb. per sq. in.? and the temperatures are in the neighbor-hood of 250°F. was investigated.

Jan 1, 1940

By F. S. McNicholas

IN the first big blast at Climax, a "loop back" (three-wire system) was used (Fig. I), with the idea of securing a wiring system that would give to all series the same amount of current. Single-phase, 60-cycle, 13,800-volt [ ] power was furnished to the blasting transformers, each of which has a rated capacity of 600 amp. at 480 volts. Two blasting leads were taken from these transformers, giving a blasting current of single phase, 60 cycle, 480 volts, with an instantaneous capacity of more than 600 amp. The blasting switch was on the secondary leads from the transformers, to avoid lag in energizing them.

Jan 1, 1938

By J. B. Mackintosh

THE quantitative determination of copper, by means of electro-deposition, offers so many advantages, that it is to be preferred, when properly executed, to all other methods for ease and accuracy. The object of the present paper is to give the results of a number of experiments made during the past few months, and to indicate some sources of error, which must be avoided in order to attain the necessary accuracy. In 1867, C. Luckow, in competition for a prize offered by the directors of the Mansfield Copper Works, submitted the following

Jan 1, 1882

Jan 1, 1919

By R. M. Keeney

Jan 1, 1915

By William E. Ford, Edward Salisbury Dana

276. Cohesion, Elasticity. - The name cohesion is given to the force of attraction existing between the molecules of one and the same body, in con- sequence of which they offer resistance to any influence tending to separate them, as in the breaking of a solid body or the scratching of its surface. Elasticity is the force which tends to restore the molecules of a body back into their original position, from which they have been disturbed, as when a body has suffered change of shape or of volume under pressure. The varying degrees of cohesion and elasticity for crystals of different minerals, or for different directions in the same crystal, are shown in the prominent characters: cleavage, fracture, tenacity, hardness; also in the gliding-planes, percussion-figures or pressure-figures, and the etching-figures.

Jan 1, 1922

By C. Gutiérrez

Flotation and adsorption studies of ilmenite with technical oleic acid, pure oleic acid, and mixtures of each of them with n-hexadecane have been conducted. From them it is concluded that the depression of ilmenite caused by a too long conditioning time is due to adsorption of the collector onto the fines produced by attrition in the conditioning cell, and that fuel oil is necessary for economic flotation of non-deslimed ilmenite ore. This beneficial effect of fuel oil is attributed to van der Waals forces, of the hydro-carbon chains.

Jan 1, 1978

By Walter J. Johnson

The coals in northern Wyoming and Montana are free-burning and non-caking and range from lignite to bituminous C in rank. Strip and underground mining are employed to supply railroad, utility, industrial, and domestic fuel. The market area includes Iowa, Nebraska, Minnesota, North and South Dakotas, Wyoming, Montana, the Pacific Northwest, and western Canada.

Jan 12, 1953

By Dorsey Hager

One of the most interesting fields in North America was discovered, early in 1922, near the towns of Sunburst and Kevin, Toole County, Mont. This field produces oil from the Jurassic beds, which heretofore have been of but little importance as oil producers, and promses to be the

Jan 1, 1923