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Jan 1, 1952

Jan 1, 1930

Jan 1, 1909

Jan 1, 1917

Jan 1, 1932

Jan 1, 1905

By W. Randolph Van Lewis

In determilling the relative rate and in fi~lding the point where different inlpurities containecl in copper-matte are eliminated during the process of a converter-blow, the follo~ving results were obtainecl : A converter was selected which was starting on its sccolld charge. The first charge after lining had finished its copper " hot," and conseqaently no copper was adhering to the sides of the lining. All the copper and granulated slag from the previous charpc mcrc dumped, thus removing ally possibility of " salting " the matte to be tested. The coliverter worked fast and well during the entire test. Periods of ten minutes were selected. The converter mas brought from the stack to secure each sanlple of matte to be

Jan 1, 1904

Jan 1, 1935

Jan 1, 1944

Jan 1, 1907

By Freeman Bishop

Before Capitol Hill hearings, primary metal producers are often called "concentrated industries" because there are relatively few companies in each category and most of them are large corporations. Capitol Hill still looks on large companies as inherently wrong, but there are about as many arguments one way as the other. Encourage Imports? Now comes Assistant Attorney General for Antitrust Richard W. McLaren to say that imports of metals and other basic materials should be encouraged to create competition for the concentrated industries here at home. Cloakroom analysts are wondering how this ties in with President Nixon's cabinet task force studying the copper price structure. This is chaired by Dr. Hendrik Houthakker, a member of the White House Council of Economic Advisers who has also indicated that the use of imports to pull down prices may be one way to create less inflation.

Jan 1, 1970

Jan 1, 1890

By James E. McNulty

Coal reserve estimates are prepared using a simple equation: the product of area, bed thickness, density and recovery factors. Each of these elements involves a degree of risk based on certain assumptions. Reserve area, thickness and density rely on certain physical data whose accuracy, reliability and sufficiency may be problematical. Estimates of recovery factors for mining and coal preparation are often subjective. Most reserve estimates assume, sometimes incorrectly, that the subject reserves will be completely extracted. The principle that certain coal resources are reserves, if they can be considered economically recoverable at the time of determination, needs to be reexamined in the light of recent market cycles. Reserve estimating requires the exercise of judgments, the validity of which reflect the qualifications, experience and objectivity of the estimator.

Jan 1, 1985

Jan 1, 1890

By R. L. Manegold

IN RECENT years there has been a decided trend toward bringing ores and coal out of open-pit and underground mines by long, sloping single-stage belt conveyors. Because the high investment cost of haulage conveyors dictates maximum speed and full loading for economy, conveyor belts are running faster than ever before, with a greater burden on the belts. In addition, larger blocks of ore are being mined and conveyed. Rougher use of large mining equipment generates more tramp iron; mechanical loading rejects nothing. Therefore the extraction of tramp iron and other deleterious materials for the protection of haulage conveyors at transfer points, chutes, and idlers is becoming an increasingly difficult job. In our experience, the best method of protecting long haulage conveyor belts is to extract the tramp iron, at least the large tramp iron, ahead of the main haulage conveyor or series of conveyors. It is most practical to collect the tramp iron at the earliest source -possible, usually directly after the primary car unloading dump or after the primary crushers, which are ordinarily not affected by tramp iron, see Fig. 1. The coal or ore from its primary source is fed by chutes or feeders onto a buffer or shock belt conveyor, a short, ruggedly built conveyor system that can be considered somewhat expendable. Its primary function is to bring the ore up to speed for transmission to the haulage conveyor. There is no assured method of protecting this conveyor from tramp iron damage at its feed end. Likewise, there is a possibility, although remote if the magnet applied to this belt is installed correctly, that the tramp iron extraction process will damage the shock belt, which is, however, short and comparatively inexpensive. Magnetic head pulleys with their maximum effective range of about 8 or 10. in. cannot be considered for large installations, even though they are desirable because of the continuous and, automatic tramp, iron removal feature. Further, the most dangerous form of tramp iron with respect to potential damage to a haulage conveyor is the long rod, roof bolt, or rail segment, which is not extracted satisfactorily because of the limited tangential contact of such an iron shape with the magnet. Magnetic head pulleys are also undesirable because the dribble or fines from the head pulley discharge at the same point as the tramp iron. Screens must be used to separate the fines from the magnetics, resulting in additional expense and loss of head room. Magnetic detectors have been used with success, but they only indicate the, presence of iron, and the conveyor belt must be stopped for its manual removal. The, stoppage of any conveyor means that all preceding equipment must be stopped or a cascade of material on the idle conveyor will result. Occasionally combinations of detectors and magnetic, head pulleys are used. The detector precedes the magnetic head pulley and detects only large pieces of tramp iron, while the magnetic pulley subsequently takes out the smaller ferrous metals. Suspended magnets overcome the disadvantages of magnetic head pulleys, detectors or a combination of both. There are several magnetic extraction problems involved in applying a suspended magnet at this

Jan 1, 1952

Mining Methods LUCIEN EATON, Chairman GERALD F. SHERMAN, Vice-chairman CHARLES W. WRIGHT, Secretary Alluvial Mining CLINTON BERNARD CHARLES H. MUNRO CHARLES JANE N H. R. NORSWORTHY Open-cut Mining Iron MAX H. BARBER J. A. MacKILLICAN Copper MICHAEL CURLEY H. B. TEMPEST Underground Mining Iron C. H. BAXTER CARL BREWER TENNEY C. DESOLLAR Copper W. B. DALY A. H. WOHLRAB R. W. THOMAS

Jan 1, 1934

By Wolfgang Pietsch

Prior publications have shown that the structure and characteristics of direct reduced iron produced by direct reduction from iron ores or iron ore pellets depend on many parameters which include process variables, such as, reduction temperature, reduction gas composition, and type or origin of the raw material. Most of the published literature deals with direct reduced iron produced in the laboratory at theoretically interesting but commercially uneconomical or technically impossible conditions. Much of the work was carried out in pure carbon monoxide in pure hydrogen, or in such mixtures of carbon monoxide and hydrogen which are of no commercial interest. Other results were obtained at temperatures which are too high and would cause sticking in large scale plants. For this reason, work was initiated by Midrex Corporation to investigate the influence of raw materials and reduction temperature on structure and characteristics of direct reduced iron. The composition of the reducing gas used to prepare the samples for this study produces results corresponding to those obtained with a typical commercial gas. The temperatures at which reduction was carried out are in a technically feasible range. This paper reports on the results.

Jan 1, 1979

TENDENCIES toward nationalization grew noticeably stronger in some areas. Late last fall Bolivia took over the tin mines of four foreign operators and handed them a bill for a fabulous amount claimed for damages. In the same breath, the price Bolivia offered to pay for the mines appeared to many to be slightly ridiculous. Many engineers felt that the country would not be able to run the mines successfully. Even if they could, some thought that the Bolivian Government would gut the orebodies in an attempt to get at rich deposits for high profits, leaving the lean ores in unmineable condition.

Jan 2, 1953

The Mexican Government is building a mill at Churunibave in Sonora to handle lead, zinc, and copper ores. This development was sparked by increased mining activity in Mexico and Arizona caused by the Korean war. Pickands Mather, acting for a group of iron ore producers, is negotiating an agreement with Steep Rock Iron Mines, Ltd. to explore and perhaps lease iron ore property covering more than 1000 acres in the Steep Rock Lake area in Western Ontario. Plans call for the early commencement of an exploratory program. Other members of the group by Pickands Mather are Bethlehem Steel, Youngstown Sheet & Tube, the Steel Co. of Canada, and Interlake Iron Corp.

Jan 3, 1951