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By D. M. Bondurant

Auger mining-extraction of coal with large diameter augers is proving profitable in recovering coal left after stripping has ceased to be economical. Its many advantages-low initial cost of equipment, low operating cost, low power demand, adaptability to selective mining, simplicity of operation, etc.-have excited the interest of some in the industry in its possibilities for underground operation.

Jan 5, 1951

A Report Of Current Activity In The Industry

Jan 5, 1951

By William L. Swager

This is the second in Mining Engineering's series of articles on sources, uses, production, and conservation of strategic minerals. "Cobalt" first in the series, appeared in February 1951.

Jan 5, 1951

A PROSPECTOR stood atop a Venezuelan mountain called El Florero just 25 years ago, and shouted to the world that he had found a large, rich new source of iron ore. But his words were lost in the big green South American jungles and besides, the world had more iron ore than it could handle. There were no crises in 1926, no major wars on the horizon, no worries about mineral supplies. In the U. S., the populace was "keeping cool with Coolidge," and the solid foundation of the economy-the steel industry-rested on a still firmer basis, the Lake Superior iron ores.

Jan 5, 1951

By R. C. Amero

FULLERS earth is a general name applied to claylike minerals that have high natural adsorptive powers. They are usually distinguished from ordinary clays by a higher content of combined moisture and a lower apparent density. The definition is based on the ancient use of the material for fulling, or cleansing woolen cloth of oil and grease; a more modern definition should mention the ability to decolorize oil and should differentiate between fullers earth, which is naturally active, and certain bentonites which only develop decolorizing power after being leached with strong mineral acids. The distinction between fullers earth and activable bentonite is not a sharp one, since all types of intermediate clays can be found that are more or less naturally active, yet more or less responsive to acid treatment. The differences seem to depend somewhat on the amount of leaching that has been effected by natural ground waters.

Jan 5, 1951

By Orville Lyons

CENTRIFUGAL force has been utilized for the dewatering of fine coal for over 50 years by means of machines commonly called centrifugal dryers. In any centrifuge the coal and water are subjected to a spinning action which usually increases in intensity as the coal progresses through the machine. This spinning action, or the centrifugal force that it induces, tears water away from coal particles and produces a dewatered coal. The effectiveness of the dewatering action for any particular machine is governed by the size-consist of the coal and the centrifugal force imparted to the water on the coal.

Jan 5, 1951

New Products Equipment

Jan 5, 1951

By Donald W. Mitchell

MINE operators have a choice of several classifications of mechanical loaders. Within each classification there are many types and makes available. Table I lists loaders on which manufacturing data as to operating characteristics are available. This paper discusses the conditions met in a mine as they affect these characteristics. It is assumed that management will provide satisfactory engineering, supervision, power, maintenance, loader service within a concentration of workings, and a balanced working cycle served by balanced production equipment. These are factors which affect the optimum operational efficiency of a loader. The conditions which determine loader choice are:

Jan 5, 1951

By Harold B. Foxhall

THIRTY per cent of the mineral wealth of the United States is obtained from seven states: Arkansas, Kansas, Louisiana, Missouri, New Mexico, Oklahoma, and Texas. This area, which produced 84,727,156,000 worth of minerals in 1948, constitutes an almost complete economic unit in relation to mineral resources essential to industry. All of these states are producers of fuels and some of metallics, but in the field of important nonmetallic industrial minerals the picture is near perfection-a mineral any one of the seven states lacks, one of the others has in quantity.

Jan 5, 1951

By H. H. Hasler

THE mining and removal of coal from two or more beds, either simultaneously or consecutively, in vertically adjacent areas have always been matters of concern to mine operators from both operating and recovery points of view. However, with the progressive introduction and use of electrical and mechanical facilities, such problems assume even greater proportions. In this paper typical cases occuring in Cambia County, Pa., are given and procedures whereby such problems may be greatly reduced, if not entirely eliminated, are suggested.

Jan 5, 1951

There is plenty of sulphur available but not at the price currently being paid for brimstone. Immediate shortages may be felt before the market adjusts, making marginal sources and by-product sulphur and acid available. (See P. 403) Government aid for mineral exploration is available and regulations governing applications are available from The Defense Minerals Administration, Dept. of Interior. lust ask for M0-5 and also for the contract form which is MP-103.

Jan 5, 1951

By J. E. Ryan

TRONA, Calif., is a miniature urban community of some 3500 people, located on the northwest shore of dry Searles Lake in the extreme northwest corner of San Bernardino County, approximately 186 miles north and east of Los Angeles. Since it is situated on the Mojave Desert, a typically desert climate prevails with wide variations in temperature between day and night, extreme daytime summer heat, and cool to cold winters. Rainfall averages somewhat less than 4 in. per year, and dust storms are common. The rate of evaporation, however, is great, amounting to 6 to 9 ft of water per year. The extremely low humidity makes the summer heat of 110°F tolerable with only a mild, temporary discomfort.

Jan 5, 1951

GROWTH of the United States to industrial supremacy in the world is mainly because of the rapid exploitation of natural resources. The easily found high grade mineral resources have been depleted and attention has turned to low-grade ores. Progress has been made from the comparatively crude mining and milling techniques, which sufficed for the rich deposits, to more complex technology for exploiting low-grade ores. In spite of this progress the defense program is pointing up the fact that the mining industry is caught short on ability to produce the needed mineral raw materials. The mining industry is digging itself out of business here in the United States.

Jan 5, 1951

Jan 5, 1951

THE Leadville tunnel, a Bureau of Mines project designed to unseal Colorado's rich but flooded lead, zinc, and manganese mines, is still being advanced, although the work is encountering severe difficulties. Work on the tunnel, begun in 1943, was dropped for lack of funds in 1945, and started again last September. The tunnel is one of the nation's toughest mining jobs. Fifty firms and individuals, who were asked to bid on the job of continuing be- yond the 6600-ft mark, didn't even answer. The work was finally taken over by the Utah Construction Co. of Salt Lake City. Since last September, the face has been moved 1000 ft closer to the flooded Leadville district mines, and to the hoped-for length of 17.300 ft. Some apparent success has already been noted, with an unusual decline in the water level in some major mine shafts reported this winter.

Jan 5, 1951

By H. LeRoy Scharon

The electrical resistivity method was utilized at 245 road cuts and structure sites over the 166 miles of the Philadelphia and Western Extensions of the Pennsylvania Turnpike System. Varying geologic structures and rock types afforded an excellent academic study of the method as well as a practical application to modern highway engineering.

Jan 4, 1951

By J. J. Spencer

IT has been found that, during any particular period of operation or in mining any particular area of the Castle Dome mine, there appears variation between mine grade and mill grade, thus Ear always in the plus direction. It would be interesting to know if this condition obtains at other properties, and, if possible, to alter the sampling methods or computations in order to get better agreement between mine and mill figures.

Jan 4, 1951

Critical Shortage of Engineers M AN POWER commitments for defense, superimposed on normal domestic requirements, exceed the available supply of labor. The armed services, industry, and the professions are sizing themselves up man power-wise and are announcing that serious shortages are imminent or already in existence. The engineering profession is facing serious shortages. The main reason for this is the recall of engineering and scientific personnel to the armed services.

Jan 4, 1951

By A. J. Zinkl

A two-year test led to adoption of carbide insert bits at the Iron King mine. Results: greater production, lower costs, and happier miners.

Jan 4, 1951

By A. O. Bartell

The rich Columbia River Basin is producing a long list of minerals useful in ceramics, farming, construction, power, metallurgy, and other industries.

Jan 4, 1951