Search Documents

Technical graduate wanted for metallurgical. work in experimental laboratory of large New England manufacturing concern. A knowledge of metallography of steel is essential. Practical experience is desirable but not required. No. 305. Man familiar with precipitating with the diamond drill core to act as foreman. No. 311. Competent mining man to develop and take charge of mines in Peru. Property to be developed from start and equipped with thoroughly modern appliances to meet the increased production. Applicant must possess considerable mechanical ability and experience. No. 312. Engineers and assistant engineers in forest production for National Defense work for the duration of war. Laboratory work conducted primarily by experimental and research methods, embracing principally investigations of mechanical and physical properties of wood, processes for the preservation of wood against decay and other destructive agents, practical problems of pulp and paper industry, and other industries utilizing wood by chemical means or otherwise. Assistance in this department of Government is urgently required in order to obtain maximum benefits from the investigation. Salary $1860 to $3000 for engineers; $1200 to $1800 for assistant engineers. No. 313.

Jan 6, 1918

By Ernest N. Patty

Placer gold-bearing gravels of interior Alaska and the Yukon are, for the most part, permanently frozen, and are described as permafrost. The first step in preparing these gravels for dredging is to strip by bulldozer the surface layer of tundra, brush, and scrub timber, and to expose the ebony colored surface of the frozen mud at the grass roots. This mud varies from a frozen, muddy ooze to a sandy silt and locally may contain layers of peat. The whole mass is intercalated with ice dikes and lenses. The thickness will vary from a few feet up to 100 ft, depending upon local conditions. A freshly exposed surface will thaw to a depth of 4 in. per day during the summer season. Common practice is to expose a large surface of this mud to the sun and each day's thaw is then swept off by water and carried away in suspension.

Jan 1, 1951

Discussion of the paper of Frederic P. Dewey, presented at the Cleveland Meeting, October, 1912, and printed in Bulletin -No. 70, October, 1912, pp. 1075 to 1101. EDWARD KELLER, Perth Amboy, N. J. (communication to the Secretary *) :-Mr. Dewey, in his paper, offers a liberal addition of new data to those already to be found in the technical literature on this subject. However, now as before, the work issuing from the U. S. mints and assay-offices conveys the impression that systematic sampling in those institutions is more or less a secondary consideration, the chief attention being given to the principle of producing approximately homogeneous bars; recourse being taken to remelting or refining the bullion. This practice has been definitely rejected in the realm of copper-bullion sampling, for the reason that in such operations there are always unaccounted losses. Does not the same objection hold true for gold-bullions; although, perhaps,in a lesser degree ? Differences of opinion would seem justified on the following statements made by Mr. Dewey: 1. "Only two classes of alloys can form homogeneous bars-those that are solid solutions, and the eutectics."

Jan 3, 1913

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 milling and metallurgical subjects; to determine the existence of mining maps, arid to furnish general 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 N. E. Grosvenor

The study of rock mechanics is becoming more important each year and several groups are currently engaged in the study of rock mechanics instrumentation and techniques that can be used to determine rock properties in place. As it becomes necessary to mine lower grade ores, larger equipment and tonnages are required, which in turn call for larger openings underground. In addition, rock mechanics studies are necessary for designing large underground openings for defense and powerhouses, and highway and water tunnels. Meramec Mining Co. has a rock mechanics program in which they are trying to develop a means of detecting ground instability prior to failure. In one case advance warning resulted in valuable lead time for back filling stopes before pillar failure had progressed to a dangerous extent.1

Jan 2, 1968

By Luis A. Fierino, M. Ashraf Mahtab

This paper reviews the background of, and solution techniques for, the major geomechanics problems affecting caving operations, including prediction of cavability, defining size distribution of or fragments, stability and support of production openings, and control of rock bursts and subsidence. Further research is also suggested in the solution of the various geomechanics problems.

Jan 1, 1984

By N. Mao

This paper presents the results of a research effort to develop a technique for estimating in situ stresses by measuring stress-induced velocity anisotropy around a borehole. Relevant parameters required to make the estimate were identified and measured in the laboratory on a 35.6 cm (14.0 in) cube of Nugget sandstone with a 10.2 cm (4.0 in) diameter hole, under biaxial loading. Two pairs each of radially and tangentially polarized transducers were placed inside the hole with displacement directions either parallel or perpendicular to the principal stress directions. With this configuration, relative travel times were measured by both a pulsed phaselocked loop technique and a cross correlation of digitized waveforms. The biaxial velocity data were used to back-calculate the applied stress. The standard deviation of the differences between the calculated and applied stresses is 0.62 MPa (90 psi) for a stress level up to 8.63 MPa (1250 psi).

Jan 1, 1984

Regulation of the Coal Industry. BY HOWARD N EAVENSON (Tech Pub 711, also Trans, vol 119 3400 words) A review of conditions in the bituminous coal industry during the last 15 years and of the attempts to remedy them through Appa¬lachian Coals, Inc, and through the NRA The lack of any provision in the so-called "Guffey" law for conservation of our coal supplies is pointed out and the efforts at regulation of the English coal industry are described Assuming that some regulation of the industry is necessary to maintain reasonable working and living conditions and that Federal control by compulsion will not be possible, the requirements for regulation

Jan 1, 1937

By J. C. Smock

The primitive mode of mining clay by open workings, in which the overlying beds of earth (commonly termed the " bearing ") were removed, and the clay then dug out by sinking shallow pits, is still the prevalent and almost universal mode of extraction. This is particularly true of our cretaceous and tertiary clays, which are generally earthy in character, and but slightly covered by drift and alluvium. The most accessible beds in many of our clay districts have been worked out, and clay miners are compelled to search for new outcrops, or to remove thicker beds of top dirt or bearing. Under this stimulus subterranean working, or mining proper, has been suggested. A brief notice of this new mode, as employed by Mr. Otto Ernst, near the head of Chesquake's Creek, three miles south of South Amboy, New Jersey, is here presented for your consideration. Previous to mining, the old mode of extraction, digging pits, was found to be too expensive, in' consequence of the heavy amount of top dirt and the excessively large amount of water in these overly

By E. A. Khopunov, V. I. Revnivtsev

The process of triboelectric separation from the point of view of its potential for selective separation of various mineral particles can be described as "dry flotation." Large scale practical applications of this technique are limited because suitable models which can describe contact charging of mineral particles have not been developed. Among the various concepts a promising one is an attempt to change development in dielectric minerals within the limits of contact phenomenon in semiconductors. Experimental investigations reported in this paper indicate that the charge development is mainly a result of contact electrification of dielectric minerals characterized by "donor" and "acceptor" type energy spectra due to lattice defects.

Jan 1, 1980

By D. Malhotra, R. M. Hoover, F. N. Bender

The paper discusses the effect of aeration and agitation on grade and recovery of molybdenite. A series of factorially designed flotation tests were carried out in a "Leeds Automatic Laboratory Flotation Cell." Analysts of flotation results indicate that molybdenite has fast floating and slow floating components. The rates of fast floating components, which do not create a problem inflotation, could be varied by changing agitation or airflow rates. However, the rate of slow floating components was stable and was only a function of residence time. Aeration has a significant effect on the grade of MoS2 and only a slight effect on the recovery of MoS2. Agitation has a slight effect on the grade, but does not effect the recovery of molybdenite. The implications of the results on the design of flotation cells and control and optimization of the existing circuits are also considered.

Jan 1, 1981

By Glenn C. Waterman

The use of stream sediment and soil sampling as an aid in exploration has markedly increased in recent years as more and more attention has been directed to areas that are generally geologically favorable for mineralization but show little outcrop. Numerous ore deposits and many hundreds of mineral deposits that have no surface exposure have been found associated with anomalous geochemical patterns. Sophisticated techniques have been developed to "wring out" of geochemical data subtle information that is pertinent in defining areas of exploration interest. Variations in metal patterns in soils and sediments as they are affected by pH, Eh, weather, topography, etc., are pretty well known. Field studies have determined the variations and controls of metal ion distribution in the several soil horizons and the contributions to metal concentrations made by different types of vegetation. Less well known is how to interpret geochemical data since thickness of soils over bedrock varies in an unknown fashion and, particularly, where glacial debris of unknown thickness is piled on top of soils or scoured bedrock.

Jan 7, 1975

By B. S. Taylor, J. D. Fraser, W. L. Chen

Steam coal quality is less stringent than metallurgical coal quality. Steam coal is prepared either by cleaning a full-size range of raw coal or cleaning coarse coal only, leaving the fine coal raw. The latter scheme is more cost competitive. It is particularly applicable to US eastern soft coal where low ash coal is concentrated in fine sizes. For raw coal size separation the Rotating Probability Screen, developed by the British Coal Board, may be used for easy change of raw coal separating size, and to avoid screen deck plugging when handling wet and clayey raw coals.

Jan 1, 1985

By J. C. Smock

THE primitive mode of mining clay by open workings, in which the overlying beds of earth (commonly termed the "bearing") were removed, and the clay then dug out by sinking shallow pits, is still the prevalent and almost universal mode of extraction. This is particularly true of our cretaceous and tertiary clays, which are generally earthy in character, and but slightly covered by drift and alluvium. The most accessible beds in many of our clay districts have been worked out, and clay miners are compelled to search for new outcrops, or to remove thicker beds of top dirt or bearing. Under this stimulus subterranean working, or mining proper, has been suggested. A brief notice of this new mode, as employed by Mr. Otto Ernst, near the head of Chesquake's Creek, three miles south of South Amboy, New Jersey, is here presented for your consideration. Previous to mining, the old mode of extraction, digging pits, was found to be too expensive, in' consequence of the heavy amount of top dirt and the excessively large amount of water in these overly-

Jan 1, 1875

By Louis A. Panek

MOST roof bolts are used in mines with bedded roofs, but it has not been determined to what degree thin-bedded roofs can be reinforced by bolting if there is no thick member in which to anchor the bolts, or what function the bolts must perform in such a case. Owing to widespread practice of sys- tematic bolting to support thin-bedded roofs, moreover, it is desirable to design roof-bolting systems on a quantitative basis. Specifically, a solution to the following problem is required: For a roof composed of beds of given thickness and physical properties, what is the optimum length, spacing, orientation, and tightness of bolts consistent with safety and economy? The investigation reviewed here has produced a functional equation to evaluate these variables and establish basic principles of roof bolting.

Jan 1, 1956

By Theodore Barry

The task of developing controls in the mining and manufacturing industries to give them a tighter grip on operating costs has afforded this author an interesting vantage point for observing certain practices common to both industries. Of course, each of these industries has problems unique to itself, but all industries have many common problems. After all, every industry is a business and every business is concerned with the task of producing its wares as profitably as possible. While many differences between businesses in different industries are known, the author is convinced through experience that the mining industry has much more in common with the manufacturing industry than is generally acknowledged. Four principal questions come to mind in the comparison of mining with manufacturing: How different are the management control methods in these two worlds? How do both industries go about the task of controlling costs? How does the mining industry compare in terms of the effectiveness of its workers? And perhaps most important, what can the mining industry learn from what the manufacturing industry is doing?

Jan 11, 1962

The Wheeler Condenser & Engineering Co., of Carteret, N. J., is now building a line of horizontal and vertical shaft centrifugal pumps for general services, as well as for condenser work.. This company has been building centrifugal pumps for over 20 years, most of them being used, however, in connection with condensers. The new line of pumps is suited for all services. A small motor-driven unit for tank or stand pipe operation is shown in Fig. 1. Referring to the sectional illustration (Fig. 2), it will be seen that this pump conforms to the most recent advances in centrifugal pump construction, having a two-part divided casing, with the suction and discharge nozzles in the lower half. The impeller is of the closed double-suction type, protected by labyrinth wearing rings. The shaft is protected from the water by bronze sleeves, which screw on to the shaft and extend clear through into the bearing bracket boxes. Bearings are of the ring-oiled type, and in the outboard bracket, is a ring-oiled thrust bearing, which is a refinement not usually found in double-suction

Jan 4, 1916

By J. Ehner Thomas, M. D. Gould

Until four years ago the market price of oil securities moved directly and immediately with the general list. This point, was first developed by the senior author in 1924 while making a statistical study of the relative movement of oil securities and the general market. Plotting the monthly averages of 17 oils against 233 industrials disclosed the sur- prising relationship shown in Fig. 1. The traditional vagaries of the oil business, the wide fluctuations in current supply and resulting abrupt changes in crude prices nevertheless produced no movements in the market price of oil securities as a group, which departed notably from the movements of the general market. Obviously general business conditions did not always change when and as conditions in the oil industry changed; clearly the fluctuations of

Jan 1, 1929

By O. W. Walvoord

ONE particular plant has been chosen to illustrate the various factors in mill design. The problems are general in nature and with various modifications are met in the design of most milling plants. Literature on modern mill design is not extensive and certainly has not kept pace with the rapid advancement in the art of ore beneficiation. Much remains to be investigated, and continued vigilance is required to give the operator and the metallurgist the best layout to meet the industry's changing requirements. The Humboldt project, a joint venture of the Cleveland-Cliffs Iron Co. and the Ford Motor Co., involves an iron ore flotation plant near the town of Humboldt, on the Marquette range of the Michigan Upper Peninsula. A crushing plant, designed for an ultimate capacity of 720 long tons per hr, is followed by a first mill unit of 70 long tons per hr. Future mill units are planned to bring the total mill capacity to 5000 long tons per 24 hr.

Jan 1, 1954

ON Coal's Horizon one development rises above all others. That is the swift expansion of output to make Soviet Russia the largest coal producer on earth next to the United States. Few Americans are aware of the speed and extent of that expansion nor of the accompanying creation of a strong, resourceful mining machinery industry, nor of the extent and character of the mechanization of Soviet coal mining. Two initial clarifications are necessary for better understanding. First, we must keep in mind the sharp distinction between the Russian people and the communist Soviet dictators who rule them. The great mass of the Russian people are not members of the Communist Party as people here are Republicans or Democrats. They are not permitted to be members. There are, by various estimates, only 2 to 4 million members of that party in all Soviet Russia. The other 196 to 198 million are the victims of their tyranny and their terror. It is the activity of the Soviet rulers that concerns us here.

Jan 1, 1954