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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 James R. Garvey

Coal reserves of the United States are enormous. Considered on the basis of proven reserves, and compared with reserves of other fuels, coal constitutes 88% of the proven recoverable energy resources of the nation. That includes oil, natural gas, oil shale and uranium used in burner reactors. Considered on the basis of "ultimate recoverable reserves", that is, those resources which can be extracted with improved technology and at somewhat higher costs and including those resources of all fuels not yet found but believed to be waiting discovery, coal still accounts for 75 % of the national total. In the U.S. hydrocarbon economy about 76% of the total energy needs are supplied by petroleum and natural gas and about 20% by coal. Domestic resources of oil and gas are running dangerously low, and assuming a continued hydrocarbon economy, the 20% supplied by coal may increase dramatically. Nearly a quarter of the petroleum consumed in the U.S. is imported. Natural gas is in shorter supply than petroleum and the problems of its importation seem at least as difficult as those of oil.

Jan 6, 1972

By Neville G. W. Cook

The ultimate goal in rock mechanics is to make quantitative predictions of the response of rock to changes. Measured and calculated values of changes in displacements or temperatures in the rock for six different field experiments are compared using linear regression. When values of the mean compressive stresses are large compared with the values of the deviatorial stresses, linear elasticity, using values for Young's modulus from laboratory tests, provides a good predictive model. However, if the values of the mean compressive stresses are small compared with those of the deviatorial stresses the behavior and response of the rock, though systematic, is not linear. Linear heat conduction provides good predictions of changes in rock temperatures but thermal displacements are not predicted well by linear thermoelasticity.

Jan 1, 1982

By William E. Ford, Edward Salisbury Dana

239, Contact-Gwiorneters. - The interfacial angles of crystals are measured by means of instruments which are called goniometers. The simplest form is the contact- or hand-goniometer one form of which is represented in Fig. 377. This contact-goniometer consists of a card on which is printed a semi- circular arc graduated to half degrees at the center of which is fastened a celluloid arm which may be turned to any desired position. The method of use of the goniometer is illustrated in Fig. 377. The bottom of the card and

Jan 1, 1922

By Robert H. Richards, E. E. Bugbee

Friends often ask how accurate the work of our little stamp mill is, or express the opinion that a little mill cannot do good work. As a reply we would like to place on record the results of a few tests. There are two periods of work in our laboratory; the fall term, when the class collectively goes through all our chief laboratory-processes, and the spring term, when the students work up their theses, each electing some one process or investigation and devoting himself wholly, or almost wholly, to that. Some of the tests, the results of which are recorded in this paper, were made in the fall term; the preparation of the apparatus, the sampling and the assaying being done largely by assistants, with the aid of the students. Others were made in the spring term as thesis-work, and the results are due wholly to. the students. The complete " tree " of our process is patterned after the-

Jan 1, 1904

LOCAL SECTIONS (There are 60 Local Sections in the United States, 4 Foreign ) ADIRONDACK Established June 18, 1952 Paul W Allen, Chairman William Webb, Vice-Chairman Edwin Briggs, Secretary-Treasurer National Lead Company Mac Intyre Development Tahawus, New York Paul W Allen, Section Delegate R G Fleck, Alternate Section Delegate

Jan 1, 1954

By Cyril Stanley Smith

BETA brass (consisting of approximately equal atomic proportions of copper and zinc) exists as a random solid solution at high temperatures, but at low temperatures [ ] an ordered structure is stable, with the copper and zinc atoms occupying alternate sites on the body-centered-cubic lattice. On cooling, ordering commences at a temperature of 450° to 470°C., depending on the composition. The degree of ordering progressively increases at lower temperatures until it becomes virtually complete at about 100°C. The electrical resistivity of the alloy illustrates the changes clearly (Fig. I). This type of reaction has been a favored subject for study by physicists. An [ ] excellent summary of the theory is to be found in a paper by F. C. Nix and W. Shockley.1 All published data on electrical conductivity, specific heat and other properties agree in indicating that the ordering reaction in beta brass takes place so rapidly that it cannot be prevented or even retarded by quenching. With most ordered alloys, cold-working induces disorder and

Jan 1, 1942

By W. H. Fluker

Until recently, the universal practice in New Zealand was dry-crushing and direct cyaniding. With ores containing no mineral sulphides, and little or no coarse gold, 'this method, in spite of its many disadvantages, gave excellent results, and was by far the best one available, pending the solution of the slimes-problem. But the situation has now been changed. The successful treatment of the slimes, enabling the mines not only to do away with dry-crushing, but also to deal with the mineralized ores of the lower levels, which are, for obvious reasons, quite unsuited to that method of treatment, has made wetcrushing universal; and this may be taken as satisfactory proof of its superiority over the former practice. In the lack of accurate information from plants operating successfully, particulars of experimental trials carried out on a working-scale at the Waitekauri Extended mine, Maratoto,

Jan 1, 1903

By David R. Maneval, Ralph A. Lambert, H. B. Charmbury

Subsidence, although it may or may not be apparent on the surface, is an inevitable consequence of deep coal mining and a frequent cause of damage to surface structures. Efforts to prevent subsidence go back many years, but there is still only one known antidote that is both technically feasible and predictable. This is the hydraulic or pneumatic stowing of solids-or flushing. In coal mines, however, flushing has been rarely used because it is considered the most expensive method of filling such mines, even though the reverse is true for ore mines. It is thus significant that the method has found favor in a comprehensive program the Commonwealth of Pennsylvania has undertaken to eliminate the hazards of abandoned coal mines within its jurisdiction. In "Operation Backfill," as the program is known, the Commonwealth has successfully used hydraulic flushing and fully justified the method economically.

Jan 4, 1967

Jan 1, 1926

By R. J. P. Lyon

It is usually assumed1,2 that ore deposition is relatively slow, taking place over tens of thousands of years. Yet many syntheses and phase changes can be completed in the laboratory in a matter of hours, under essentially the same pressure and temperature conditions to be expected in nature. Much has been written about geothermometry, and Ingerson's recent summary2 can hardly be surpassed. Rather than review the whole field, this article will deal specifically with diffusion rates in solid solutions* of the sulfide minerals.

Jan 11, 1959

By Donald N. H. Chi, Henry E. Perlee

Accident cost data bases for all mining sectors covering the period 1975 through 1980 have been created on the PDP-11/70 and VAX-11/780 computers at the Bureau of Mines Pittsburgh Research Center. The total expected costs of the following tangible elements are computed: (a) loss in personal income; (b) compensation of wages from State, Federal, and union funds for disabling injuries; (c) benefits for injuries resulting in death or permanent disability; (d) medical treatment and hospital care; (e) investigation of a fatal accident; and (f) production loss due to accidents involving fatalities or amputation injuries. Each cost record computed contains a reference to the original record in the Health and Safety Analysis Center (HSAC) accident files to permit concurrent analysis. The intended applications include examinations of annual trends in mine accident statistics on the basis of economic loss. This provides an additional perspective on mine accidents. Various examples of the use of these data bases are presented.

Jan 1, 1983

Western Mining Corp. has announced plans to expand its mining operations at Kambalda, and to build a nickel refinery at Kwinana, near Perth, Western Australia. The refinery will use the ammonia-leach hydrogen reduction processes of Sherritt Gordon Mines Ltd., and it is expected that by 1970, when the expansion is scheduled for completion, Western will be the world's fourth largest nickel producer. Although estimates have not been finalized, the total cost is expected to be about $55 million. The mine and mill facilities at Kambalda, which began production in June 1967, are now producing at the rate of 11 million lb of contained nickel per year. The company estimates the sulfide ore reserves at Kambalda and St. Ives at 10.4 million tons averaging an usually high grade of 3.8% nickel, or about 790 million lb of contained nickel. In addition, silicate and oxidized ores have been located in both areas.

Jan 3, 1968

By Iichiro Omori

THE Mabuki process, a Japanese hearth process for the treatment of matte, uses the same princi-ple as the Bessemer steel process. The only difference between the two is that in the Mabuki proc-ess a hearth furnace, not a converter, is used. Though the hearth is not as good as the converter, the first cost is very low and the capacity is compara-tively small; so the process is most suitable for smelters FIG. 1.-PLAN AND SECTION OF HEARTH. having a small production. To construct the hearth, an excavation, 6 ft. in each dimension, is made in the ground and a drainage channel is dug at the bottom. Then all side walls are faced with stone or slag brick and the cavity is filled with fireclay or brasque, except the hearth at the top.

Jan 9, 1922

By H. L. Monroe

Meramec Mining Co., owned 50% by St. Joseph Lead Co. and 50% by Bethlehem Steel Corp., is engaged in mining, concentrating and pelletizing iron ore from the Pea Ridge Mine which is located about 75 miles southwest of St. Louis. The Pea Ridge orebody lies under some 1300 ft of limestone, dolomite, shale, and sandstone. It runs from east to west for about 1/2 mile and varies in width up to a maximum of around 600 ft. The orebody dips about 80" S. The ore is high grade magnetite with some local zones of specular hematite. The Precambrian country rock is rhyolite porphyry.

Jan 12, 1965

By S. Tiwary, S. Samanta, B. N. Pandey, N. C. Saxena, R. Sinha, B. P. Nandy, B. Singh

Subsidence investigations over one bord and pillar and one longwall caved panel at Dhemomain colliery showed that, although the width-depth ratio (0.82 and 0.83) and working and strata conditions were almost identical, the maximum subsidence over bord and pillar panel was 46.2 per cent of extraction thickness against only 6.9 per cent over longwall panel. The angle of draw was 13O to 210 and 66 to 95 per cent of the subsidence had taken place immediately after extraction. The subsidence profiles were not symmetrical and were of funnel like shape. There was wide variation in subsidence movements over caved faces in India mainly due to difference in the composition of supercumbent strata.

Jan 1, 1983

By R. W. Jenkins, O. J. Neslage

The need for mechanized drilling to decrease mining costs has resulted in the development of the jumbo from column-and-bar drill by carriages to hydraulically controlled jib jumbos. Resultant savings from use of improved jumbos have been high enough usually to retire the machinery investment within a year. The jib jumbo unit has been and applied successfully to development and preparation programs and flat-bedded stopes, and an even wider field is forecast for its use.

Jan 5, 1950

By R. H. Wightman, G. H. Adams

H. C. WEED*—Referring to the use of "dummy fuse" for checking the shots in chute blasting operations, I believe that an even better practice is to blast the chutes with no delay electric blasting caps. Permanent wires can be strung through the grizzly lines and the lead wires from the shots attached to these lines. Using this method, no time is lost in spitting the individual fuses. The possibility of a fused charge becoming dislodged by previous shots and falling into the chute below is eliminated and there is no chance of a man walking back into his own blast. A small hand twist blasting machine or a radio "B" battery can be used to fire the shots if the lines are fired individually. If so desired the entire area can be blasted at once by a switch at the manway or in the drift below. providing a sufficient source of electricity is available. In case a switch is used, proper precaution for locking the switch must be provided. R. H. WIGHTMAN (author's reply) —We do use electric blasting when the number of shots is large; but we have found it more satisfactory to use fuse and caps for individual shots on the grizzly.

Jan 1, 1950

THE fall meeting of the Petroleum Division of the American Institute of Mining and Metallurgical Engineers will be held in Fort Worth on Oct. 19 and 20. The Texas Hotel will be headquarters. for this meeting, the technical sessions being held in the ball-room of the hotel. During the evening of the nineteenth a smoker will be held at the Fort Worth Club. In working out the program for this meeting, J. B. Umpleby, vice-chairman for production engineering, considered it especially desirable to offer as complete a discussion as possible of the subject of air-gas lift, its theory and practice, and its relationship to gas-oil ratios. The entire first day will be devoted to sessions on this subject. One session of the second day will be devoted to the use of electricity in oil-field operations and the second to the handling of congealing oils and paraffin. In addition to this program there will be one or more sessions when petroleum engineering research problems will be discussed. This meeting of the Division is primarily devoted to production engineering, as will be seen from the pro-gram. During one of the sessions, however, a brief review with forecasts of the production situation will be presented.

Jan 8, 1927

By Toshimitsu Kokubo, Yoshio Yamagata, Tadao Moro, Kenji Tomita

Owing to the traffic jam in collection, and transportation of wastes, the air- and water- pollution in incineration plants, and the sanitary trouble in reclaimed land, it seems that the defective existing system of the solid waste treatment in Japan can not follow the change in quality and the increase in quantity of solid wastes. Under these situations, the objective of the municipal solid waste treatment must be to actualize the pollution-free system for environmental protection and the resources recovery system for resource- and energy- saving. From this point of view, AIST of Japan is now engaged in the research and development of the resources recovery system from municipal solid wastes. This paper reports on the outline of the development of resources recovery technology in Japan, including the AIST's project on this matter.

Jan 1, 1976