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By Charles F. Brush

THE compression of gases to a very high degree, for purposes of scientific research, has long presented serious difficulties to the physicist. Great advances have been made of late years in the construction of ordinary air or exhaust pumps, while very little has been done towards the improvement of compression pumps. The principal difficulties encountered in the construction of such apparatus are the existence of the so-called "dead space" in the pump barrels, leakage of the piston packings under high pressure, and the trouble arising from the unequal expansion of parts caused by the development of the latent heat of the gas during compression. Of these obstacles to success, the "dead space" is far the most serious, as it fixes a limit to the performance of the pump beyond which it is impossible to carry the compression. The writer having occasion, some time since, to make a series of investigations on gases very highly compressed, and finding no apparatus, or description of apparatus, adequate to produce the required

Jan 1, 1876

Jan 2, 1966

The Library of the above-named Societies is open frond 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 front 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 neaps, and to furnish general information on the geology and mineral resources of all countries. All communications should he 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 1, 1917

By Richard P. Rothwell

The anthracite coals of Pennsylvania are all mined from large veins. A seam less than four feet. in thickness is generally considered as unworkable, those from which most of the coal now comes being from 8 'to 30 feet thick. The system of mining employed is, almost without exception, that known as " chamber and pillar work;" that is, the coal is taken out of chambers of from 18 to 30 feet in width, and pillars of from 12 to 20 feet are left between these to support the roof. In general, the entire thickness of the seam, even

By J. R. Cooper, A. Bruynesteyn

The final results of the operation of the Cananea test dumps are discussed. Scale-up factors between shake-flask tests, column tests and the large test dumps are established for the Cananea ore. The formation of clay layers, which formed inside the dumps and markedly affected extraction, as well as secondary enrichment, are discussed.

Jan 1, 1974

By F. X. Tartaron

F. C. Bond (Consulting Engineer, Processing Machinery Dept., Allis-Chalmers Manufacturing Co., Milwaukee, Wis.) — Papers such as this one which deal in a lucid manner with the obscure fundamentals of comminution theory are always welcome. The author has attempted to bring together several diverse theories and handles them interestingly. However, some of the ideas expressed and conclusions drawn require critical reviewing, for which amenities alone will not suffice. The author points out that the theoretical energy required to break across crystal lattices is of the order of 1000 times the actual energy required to crush or grind, and that this energy in turn is perhaps 1000 times the measured surface energy of the new surface area produced. The energy required to grind commercially is controlled by flaws and dislocations, rather than by the inner strength of the lattice structure. The measured surface energy is only a slight residue left after the face atoms are adjusted to their new environment. The dislocations in the crystal lattice structure, with a spacing of about O.l,u, or

Jan 1, 1962

By Charles E. Wait

The old laboratory at the School of Mines was among the notoriously bad ones, being situated in apartments of the main collegebuildings not originally intended, and conspicuously unfit, for the use to which they were put; while, as in many of our schools and colleges, the assaying was done in the basement of the college. Prominent among the disadvantages of such an arrangement are insufficient light, poor ventilation, and little or no provision to carry off offensive gases. It is not my intention now to present a complete description of this building. I wish merely to call attention to a few points in its construction and equipment, which may prove of interest to those who contemplate erecting buildings for snch work, and who may be, as we were in this instance, limited as to funds. In this laboratory every room is well lighted; all rooms used by students are well ventilated, and are provided with closed hoods for

Jan 1, 1887

By F. F. Aplan

Pollution control will be of utmost importance in the 1970's. In this area, the mineral process engineer has a special competence to understand and remedy many pollution situations. There is an old adage that goes, "Build a better mouse- trap and the world will beat a path to your door." Would that it were so, but the reality of the situation is such that, just as a supplier must sell his machine, a professional man must sell his competence. It is a sad but true fact that mineral processing engineers have not done a very good job in selling their extensive competence in the control of a broad range of pollution problems. Recently one of our students visited a paper pulp mill where he was shown a foam fractionator used to remove paper pulp fibers from plant discharge waters. "Foam fractionator hell, that's a flotation cell!'' was his comment. Ah so, it would appear that large numbers of technical people consider themselves experts on "foam fractionation" Or is it that we have been very remiss in demonstrating the usefulness of our equipment and processes and our professional competence to solve, these pollution problems?

Jan 1, 1970

By Charles F. Brush

The compression of gases to a very high degree, for purposes of scientific research, has long presented serious difficulties to the physicist. Great advances have been made of late years in the construction of ordinary air or exhaust pumps, while very little has been done towards the improvement of compression pumps. The principal difficulties encountered in the construction of such apparatus are the existence of the so-called "dead space" in the pump barrels, leakage of the piston packings under high pressure, and the trouble arising from the unequal expansion of parts caused by the development of the latent heat of the gas during compression. Of these obstacles to success, the "dead space" is far the most serious, as it fixes a limit to the performance of the pump beyond which it is impossible to carry the compression. The writer having occasion, some time since, to make a series of investigations on gases very highly compressed, and finding no apparatus, or description of apparatus, adequate to produce the required

By S. R. Gilbert, B. W. Burdett, L. B. Hales

A brief review of grinding control systems is given with a review of the most popularly reported control loops. The trend toward more sophisticated control systems in terms of control strategies and control equipment is discussed, and the reasons for the popularity of distributed control equipment are outlined. The evolution of the interface between the operator and the process and its importance in plant control is described. Finally, the authors' view is given as to the future of grinding control.

Jan 1, 1984

By A. M. Gaudin

IN flotation lime is used to depress pyrite. For this purpose it is preferred to caustic soda. The low cost of lime and the widespread availability largely account for this preference. However, there is some evidence1 that pyrite is more readily depressed by calcium than by sodium ions at the same pH. To measure the difference in adsorption of calcium and sodium, which is thought to lie at the basis of the differences in depressing action, radionuclides of

Jan 2, 1953

By Edwin B. Johnson

The success of self-fluxed sinter in enhancing the operation of the blast furnace during the past few years has reasonably led to the assumption that the use of self-fluxed pellets might result in even greater furnace efficiencies. A great share of development work in agglomeration has been directed towards techniques related to the production of self-fluxed pellets, but no appreciable tonnage of self-fluxed pellets had been produced on a commercial scale until this past year when The Cleveland-Cliffs Iron Co. produced 35,000 tons of such pellets by the grate kiln system at the Republic mine during the period May 21-June 5, 1962.

Jan 3, 1963

By M. S. Klima, P. T. Luckie

Interfacing new or improved unit operations SUBMODULES with the EXECUTIVE of a macro analysis simulator usually requires modification of the input data. For example, particle processing SUBMODULES that are sufficiently general in nature to provide useful predictions require input data for rather narrow size fractions. Such data is not always available for the EXECUTIVE and must therefore be generated by the SUBMODULE. A successful interface to allow incorporation of a new SUBMODULE for comminution and one for classification in a general stream state flowsheet simulator is presented. The general nature of the SUBMODULES, as well as the logic of expanding and contracting the required data input is discussed.

Jan 1, 1983

By Hu Weibei

This paper describes the development and implementation of the control system in the flotation plants of China. The control system can be categorized as: Control in the crushing circuits: Automatic control of the flow rate of the crusher. Control in the grinding circuits: Control of the feed rate of the grinding mill and circulating load. PSM-200, an indigenous particle size monitor, and gamma-ray density gauges are utilized. Control in the flotation circuits: pH control, flotation reagent dosage estimation and control, pulp level control, aeration control, etc. Complete grinding-flotation circuits control is based on minicomputer operations. Some typical control systems which have been applied in copper flotation plants are summarized and specific problems discussed.

Jan 1, 1984

By Claudia Gasparrini

Silver occurs in nature in major, minor and variable amounts in a very large variety of minerals and in several mineral species in the same ore. Because these minerals may respond differently to the same flotation or leaching agents, detailed studies to establish the correct silver mineralogy become essential for optimum recoveries in those situations where the silver is treated as a primary product. On the other hand, fine grain sizes, which often affect gold recoveries, are not generally as critical in silver metallurgy, due to the lower market price which allows for more of the element to remain In the tailings before incurring in economical losses.

Jan 1, 1984

By Francis L. Vinton

THE eccentric theodolite I exhibit is one constructed by the Stack-poles of New York, from drawings, considerably modified, of Combes's theodolite. The telescope is on one side of the horizontal limb, and the vertical circle is opposite to the telescope; thus they nearly balance each other, making already the construction lighter than in the instrument of Combes, where the telescope and vertical circle are together on the same side, and are both balanced by a considerable weight. The instrument stands upon three levelling screws or feet, an improvement upon the old or general style of mounting a transit on four feet-for indeed the instrument is easier levelled, and, more-over, stands more stable on three than on four points of support. The general advantage of an eccentric theodolite is evident, namely, that it can measure any and all vertical angles, from 0 to 360, without being interfered with by the horizontal limb as is the transit; besides this advantage, it needs no preparatory adjustment or correction for eccentricity ; on the other hand, however, that correction

Jan 1, 1873

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 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 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. HARRISON W. CRAVER, Director.

Jan 4, 1919

INTO their great Pacific Northwest counting house went the members of the Industrial Minerals Division recently, to count their blessings amidst the scenic grandeur and mineral wealth of the State of Washington. From their vantage point in Seattle, those who attended the IMD's fourth Pacific Northwest meeting turned their sights to the South and Southeast, scanned Montana, Idaho, Oregon and Utah, and predicted a very healthy economic future for their region. The praises of Idaho's booming phosphate industry were sung by Earl W. Murphy, secretary of that State's Chamber of Commerce. He said the establishment of Fort Hall, on the banks of the Snake River near Pocatello, first turned the eyes of the world toward what is now the center of the greatest known deposits of phosphate rock-the section adjacent to the common corners of Idaho, Wyoming and Utah. With the founding of Fort Hall, Mr. Murphy said, historians will also rank the construction of the first electric furnaces for the production of elemental phosphorous as equally significant in the commercial history of the West. Those furnaces were installed only last year by the Westvaco Chemical Div. of the Food Machinery & Chemical Corp. at Pocatello, at a cost of $8 million.

Jan 7, 1950

By Maurus Seet

Mainland China, with one-fourth of the world's population and one-tenth of its coal production, can no longer be ignored as a considerable force on the world energy scene. In terms of annual productivity, China's 300 million tons of coal rank third behind the Soviet Union with 655 million and the United States 557 million (1968 Minerals Yearbook. USBM). When viewed from another angle, 1967 figures show that increased productivity from all coal-producing continents, with the exception of North America, was led by Chinese-dominated Asia with a 19% gain. Not unpredictably though, China, on a per capita basis, is closer to the bottom of the list among members of the industrial community. Despite its misspent youth, and despite the set- backs caused by the Big Leap Forward of the late 50's and the Cultural Revolution of the late 60'S, the People's Republic has managed to make some impressive strides in developing its coal industry over the past twenty years.

Jan 1, 1971