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By P. Shahinian, M. R. Achter

P. Shahinian and M. R. Achter (U.S. Naval Research Laboratory)—We should like to point out another instance where concentration of impurities in grain boundaries led to an embrittlement. In this case an impure nickel (99.8 pct) developed many more in-tergranular cracks during creep in a nitrogen atmosphere than in vacuum.5 In comparison high-purity nickel (99.99 pct) exhibited a much smaller atmosphere effect. We concluded that the interartion of the nitrogen with nitride-forming impurities concentrated at grain boundaries promoted inter-granular cracking.

Jan 1, 1965

WITH the present mobilization program in full swing and the enrollment in engineering colleges dropping off, many solutions are offered to relieve the shortage of trained men in the engineering profession. Industry can absorb about 30,000 engineers annually, according to the Engineers Joint Council, and forecasts indicate that the number graduating will have dropped from 38,000 in 1951 to about 12,000 in 1954. If this condition were to continue there would probably not be enough people with technical training to run industry in four or five years.

Jan 12, 1951

Carlisle: I'm in the office of Comar Wilson in London. Comar is going to be good enough to talk about some of the very interesting things that have happened to him during a full, active, exciting life. Let's start in and find out where you were born, where you went to school, etc. Wilson: My parents lived in the heart of the Lake District in Cumberland, England. My father had about a half-interest in a small lead mine which he ran. He was quite non-technical, but he ran it.

Jan 4, 1965

By William Gilman

IN the past five years, and without much fanfare, Turkey has emerged as a significant figure in the world mining picture. This has been accomplished by a five-year plan now in its last year. A second five-year plan is already under way, ahead of schedule. It will concentrate even more than the first in developing Turkish mines in order to increase present exports of coal, chrome ore, and copper, and to develop new mineral exports as well. To be fully understand the republicic?s mining program should be considered as something more than merely tapping rich resources in the East along the Aegean Sea, in the North among the mountains descending to the Black Sea, and in the West at the foot of the Taurus Mountains. It should also be viewed in the light of a strong nationalist policy with many aspects of state socialism. Turkey declares frankly that all mineral re- sources belong to the nation and all exploitation should be by the state for the twin purpose of modernizing the state and securing foreign exchange for the state by exports. Accordingly, the principal mines are state-operated and a few lesser enterprises, although not state-owned, have at least been put in the hands of Turkish capital.

Jan 1, 1938

By A. C. Dittrick

THE Simon-Carves washer, originally known as the Baum jig washer, was first built in Europe about 1892. It was probably the first washer to use intermittent pressure of air on water in one part of the wash box to obtain water pulsations in another part. This type of washer was also the first to successfully clean various sizes in the same unit. Previous practice was to size closely before washing. Today there are several large firms abroad, and a few in the United States, that are constructing the Baum type washer. The design of all is practically the same, their differences being only in details. In 1928, the Hanna Coal Co. first gave consideration to the question of coal cleaning. It was believed at that time that by efficient removal of so-called noncombustibles appearing in the Pittsburgh No. 8 seam, certain markets that had been lost due to poor preparation might be recovered. Mechanical cleaning and mechanical loading were under consideration. This type of cleaning was considered the most practical means of removing impurities in the sizes below 4 in. It was decided to adopt mechanical cleaning and develop a system of mechanical loading that would be successful on No. 8 coal.

Jan 1, 1935

(Under this heading will be published notes sent to the Secretary of the Institute by members or other persons. ) An experienced gold and silver metallurgist specializing in cyaniding is desirous of obtaining a position in 'America. Speaks, Mexican Spanish fluently. A member, a. technical graduate, with four years' experience in railroad work and-general construction, two years' on mine examination and geological reconnaissance, and two a half years' drilling exploration in placer work and petroleum, together with prospecting and geological interpolation, desires a position as a mining engineer or mining geologist. An experienced mine superintendent, manager, or field engineer, is open for engagement. He has had 12 years' experience as superintendent and manager of large mines in the United States and Mexico, and experience in mine examination. A member of the Institute with several years' experience in mining in the Lake Superior copper district, is open for engagement.

Jan 7, 1913

By J. R. Hillebrand

From the abstract, "A realistic ore deposition model to serve as a conceptual framework." Further, on page 246, "The first area of study was the Josephine peridotite, now identified as an ophiolite terrane, located in northern California and southwestern Oregon (Fig. 3). Here, it was felt that we could test the models shown in Figs. 1 and 2 and, if successful, expand the model and test it in other chromite districts in the US and around the world." My comments refer only to chromite deposits in Europe and the Middle East. First, I question that may chromite deposits occur in the idealized ophiolite section shown in [Fig. 1]. Second, although some podiform deposits (referring to morphology) have been important (Gulernan, Turkey, for example), the stratiform deposits are of greater importance in tonnage and frequently grade. Examples include Nada, Yugoslavia; Bulqiza, Albania; Xerolivado, Greece; Saranovsk, Russia; and Abdasht, Iran.

Jan 1, 1984

By John C. Smock

George Hammell Cook was born at Hanover, Morris County, New Jersey, January 5, 1818. His early education was obtained in the country school, and he was, for a short time, a teacher in his native town. In 1836 he was engaged, as a civil engineer, in making surveys and locating the line of the Morris and Essex Railroad from Newark to Morristown, and the extension of the road to the Delaware River. Appreciating the advantages of a thorough education, and seeking a wider field of usefulness, he entered the Rensselaer Polytechnic Institute at Troy in 1838, and, was graduated from that .school in 1839. In this institution he heard the lectares of Amos Eaton, the famous teacher, from whom so many of our older scientists caught their inspiration and love for the natural sciences. After graduation, he was employed as a tutor in the school, and subse-

Jan 1, 1890

By C. G. Albert

The literature of paper technology contains a number of articles having reference to developments in the field of coating and filler clays for use in paper manufacture. Much of this information has not been included in mining publications and has therefore not been readily available to all in the mineral industry. Recent developments in this field, including spray drying of clays, are presented here. U. S. Bureau of Mines figures for 1952 indicate that the paper industry consumes more than 50 pct of all kaolin produced and sold in the U. S. As most of the kaolin used by the industry comes from Georgia producers, the fraction of their output destined for paper use is thus appreciably higher than 50 pct. Small wonder that the kaolin industry, especially in Georgia, is highly sensitive to the quality requirements of paper mills and must respond promptly to technological developments in paper manufacturing.

Oct 1, 1955

By H. Rumfelt

Strip mining in the domestic coal industry is contributing a greater proportion bf overall production than at any time in the past. U.S. Bureau of Mines statistics show that the percentage of total production mined in 1958 by stripping methods increased to more than 30 pct, up from 22 pct in 1951. The tendency to favor strip and open pit mining exists in other mining activities, but such trends are not as clearly outlined as in the coal industry. Significantly, the depth of overburden in coal properties considered suitable for stripping is also increasing. A depth of 50 to 60 ft of overburden was once considered to be about the maximum amount that could be handled economically. Today, a depth of 80 to 100 ft is frequently taken into consideration for simple overcasting operations (i.e., excavating overburden and dumping it in the spoil position where it remains indefinitely).

Jan 5, 1961

By Clinton L. Miller

MINING operations have been carried on in the immediate area of the Elizabeth mine during periods of high copper prices since 1793, when copperas and vermillion were first won from the outcrop. Present operations started in 1942 as a war baby. Since then production has totaled 1.7 million tons of 1.8 pct Cu ore. Elizabeth mining operations are on a pyrrhotite- chalcopyrite orebody contained in a gently plunging amphibolite syncline. The oreshoot varies in width from 10 to 40 ft, and in the area under consideration is about 150 ft in vertical extent, and more than 1000 ft long. Surface pits or cuts have been worked in three areas along the outcrop, with one pit just completed and a second in full production. Present production is 24,000 tons per month, of which 6000 to 7000 tons is trucked from the open pit.

Jan 11, 1954

By R. F. Miller, R. F. Campbell

Sixteen steels containing different combinations of chromium and molybdenum, in amounts up to 5 per cent of each element, were examined for microstructure and hardness after air cooling and after furnace cooling from suitable austenitizing temper- atures. Diagrams summarizing the structnres and hadness resulting from these two cooling rates are presented (Figs. 3, 4, 7).t Data were also obtained on the influence of these two elements, individually and in combination, on the depth of decarburiza-tion observed after furnace cooling (Fig. 8). Composition of Material The chemical composition of the steels investigated is given in Table I. The plain carbon steel was made in a 2 5-ton Heroult electric-are furnace, while the alloy steels were made in a 4.5-ton Ajax-Northrup elec- tric induction furnace. The cast ingots were hot-rolled to 1.75-in. bars. Air-cooled Series The I.75-in. bars were forged to flat plates, 0.25 in. thick, from which specimens 0.5 in. wide by 2 in. long were cut. The specimens were pretreated to improve their homogeneity by heating to 1830°F. (I000°C.) for 20 min. and oil-quenching. They were then reheated to 1740°F. (950°C.) for one hour and air-cooled, after

Jan 1, 1942

By R. F. Campbell, R. F. Miller

Sixteen steels containing different combinations of chromium and molybdenum, in amounts up to 5 per cent of each element, were examined for microstructure and hardness after air cooling and after furnace cooling from suitable austenitizing temper- atures. Diagrams summarizing the structnres and hadness resulting from these two cooling rates are presented (Figs. 3, 4, 7).t Data were also obtained on the influence of these two elements, individually and in combination, on the depth of decarburiza-tion observed after furnace cooling (Fig. 8). Composition of Material The chemical composition of the steels investigated is given in Table I. The plain carbon steel was made in a 2 5-ton Heroult electric-are furnace, while the alloy steels were made in a 4.5-ton Ajax-Northrup elec- tric induction furnace. The cast ingots were hot-rolled to 1.75-in. bars. Air-cooled Series The I.75-in. bars were forged to flat plates, 0.25 in. thick, from which specimens 0.5 in. wide by 2 in. long were cut. The specimens were pretreated to improve their homogeneity by heating to 1830°F. (I000°C.) for 20 min. and oil-quenching. They were then reheated to 1740°F. (950°C.) for one hour and air-cooled, after

Jan 1, 1942

By George A. Guess

THE increasing demand for greater speed and more accuracy, in making daily assays of ores and products from mills treating material containing but very small quantities of lead and copper, has caused the older analytical methods to be supplanted by new ones devised to meet the needs of modern work. For " control " work in copper analyses, I had, previous to the present equipment, introduced in my laboratory the ordinary electrolytic method, using hollow cylindrical electrodes, and with these I began a series of experiments in determining the lead-content of daily mill-samples and controls. The results, proving accurate and satisfactory, I then devised, with Mr. H. E. T. Haultain, a cheaper electrode than the ordinary jacket electrode, which costs from $15 to $20,-the expense of the older form making the installation of many units very costly. The form of cathode finally adopted as the most satisfactory, shown in Fig. 1, is cut from 0.001-in. platinum foil. It is 12.5 cm. long, and is divided into a blade 4 cm. wide and 6.25 cm. long, and a tongue 0.7 cm. wide and 6.25 long, the immersion area being 50 sq. cm. and weight 1.5 grams. The blade is first sand-blasted and then corrugated lengthwise, in order to impart the necessary rigidity. Strips of platinum foil 0.001 in. thick, 12.5 cm. long and 0.5 cm. wide, having a median corrugation, form the anodes. Three electrodes are used in each cell, one anode in the middle and one cathode oil each side of the anode. These electrodes are connected to slotted alumi¬num terminals, in which they are held by contact pressure. The terminals are -in. rods, projecting 2 in. horizontally in front of the wall of the cabinet.; at the back the middle electrode (anode) is connected with one pole of the current, and the two outer ones (cathodes) with the other pole.

Nov 1, 1905

By R. J. Quigg, G. P. Conard, J. F. Libsch

IN a recent investigation of the Mn-Ge system by Zwicker it was reported that two inter-metallic compounds in this system, Mn,Ge, and Mn,Ge,, exhibited ferromagnetic properties. Of these, Mn,Ge, was reported as "strongly magnetic" and Mn,Ge, was said to be "weakly magnetic" but no actual values were given. In a study of magnetic alloys of nonmagnetic elements sponsored by the United States Army Signal Corps at Lehigh University, test bars having the nominal composition of these compounds were prepared by pressing elemental powders and sintering them in a purified helium atmosphere. Magnetic values obtained on these compounds are reported in Tables I and 11. It should be cautioned that the test bars were somewhat porous and that X-ray patterns run on these materials indicated that the homogenization in the samples was not complete, but that in each case the compound reported on was the dominant phase. The (B-H) max and particularly the Br values for pure dense M&Ge, can, therefore, be expected to be somewhat higher than those reported herein, while those for Mn,Ge, may be in error in either direction. Further details on this investigation are available in previous publications.23

Jan 1, 1956

By W. J. C. Venter

The use of activated carbon to improve the selectivity in the separation of base metal minerals from bulk concentrates played an important role in the development of separation techniques employed at Tsumeb and Kombat mines. The Kombat mine, owned and operated by Tsumeb Corp. Ltd., is located in the Otavi Valley in the northern part of South West Africa, approximately 213 air miles north of Windhoek and 38 air miles south of Tsumeb, at latitude 19° 43'S and longitude 17º 41'E. The mine is linked to all major centers by both national railroad and tarmac highway systems which pass right through the town. The Otavi Minen- and Eisenbahn-Gesellschaft (OMEG) mined ore on the farm Asis from 1908-1925. Tsumeb Corp. Ltd. acquired the mineral rights in 1947, started diamond drilling in 1954 and commenced mine development in 1960. The mill started production in 1962 when proven ore reserves were 3,378,084 st containing 2.85% Cu and 2.90%Pb. Annual production of 248,411 st was increased in May, 1967 to the rate of 422,990 st, which was still being maintained in 1971, when ore reserves stood at 3,054,701 st of grade 1,91% Cu and 2.5% Pb.

Jan 4, 1973

By H. B. Charmbury, D. R. Mitchell

Everyone in the coal industry from top management to the preparation engineer is vitally interterested in recovering as much salable coal as possible from the run-of-mine product. Coal losses from a preparation plant occur in the solid refuse material being discharged from the plant and in the bleed-off slurry from the water circuit. The refuse is generally hauled from the plant in solid form by trucks, conveyors, or aerial trams to the refuse or culm banks or it may be crushed and transported by hydraulic methods to refuse ponds or dams. The loss of coal in refuse material and the extent of this problem has been covered in another paper. The loss of salable coal in the plant bleed-off slurry is one of the water circuit problems in coal preparation plants. Slurries originate at various places in the processing circuits and are usually disposed of by transportation to waste ponds known as slurry ponds. Even though the combustible material discharged as slurry and refuse from the plant is labeled a loss, the loss must only be considered temporary. There is a tendency at the present time to examine refuse and slurry losses and to reprocess these materials to recover valuable coal.

Jan 1, 1960

By Felix Wunsch

WHILE the effect of the cold-junction temperature has been known by many, its consideration has been ignored in a number of installations, resulting at tunes in a very considerable error. In fact, the magnitude of this error may amount to over 100° in some cases. While hand-operated correcting devices for portable checking pyrometers may be entirely satisfactory, it is, of course, desirable to have such apparatus en¬ Millivoltmeter Thermocouple Platinum Wire Mercury FIG. 1.-EARLY `METHOD OF AUTOMATICALLY COMPENSATING FOR COLD-JUNCTION TEMPERATURE CHANGES. tirely automatic, when applied to curve-drawing or printing pyrometers, otherwise there is no assurance that the record is correct. Numerous methods for automatically compensating for cold-junction temperature changes of thermocouples have been proposed and used in connection with millivoltmeters. One of the earliest proposed was that shown in Fig. 1. A bare resistance wire was immersed in a column of mercury located near the cold junction of the thermocouple. An increase in temperature near the cold junction resulted in a rise of the mercury column, which short-circuited more of the resistance wire causing an increase in the potential difference across the millivoltmeter, which compensated for the decreased electromotive force of the thermocouple.

Jan 9, 1919

By R. V. Ramani, George W. Luxbacher

Computer simulation of mine ventilation systems, after a slow start in the early sixties, is gaining increasing acceptance for planning, design, and evaluation purposes. Numerous programs are readily available from government, university, consulting, and industry sources. The computer adage "garbage in, garbage out" is as applicable in ventilation engineering as in any other application of computers, and has been responsible for the questionable results obtained in some instances. The source of input data for a ventilation simulation is most often a pressure-quantity survey of the mine, or, in the case of a new mine, information derived from a survey of an existing mine which has conditions similar to those expected in the new mine. The crucial step is to generate simulation input data from the ventilation survey. Problems such as quantities that do not balance, pressure gradients opposite to measured air flow, differences in the pressure datum in a multi-shaft mine, modeling of leakage, and deviations in flow from the square law (H=RQ2) are frequently encountered and must be resolved. The purpose of this paper is to discuss these aspects and to propose procedures which can lead to input data for valid simulations of mine ventilation systems.

Jan 1, 1982

By W. H. Adams

During the years when Americans were most active in investigations of the many substances containing nitrogen or ammonia, viz.: 1869 to 1875, my connection with certain chemical industries led me to experiments in the direction of the recovery of wastes from coal-gases. I take from my notes such memoranda as I think will be of interest, in the hope that some benefit may be derived therefrom by engineers at present attempting to utilize the waste products from coke-oven and blast-furnace gases. An examination of the conditions governing the manufacture of gas along the Atlantic seaboard, and an intimate knowledge of the mine-products used by the different large works, naturally led me at first to consider the well-known foreign methods of concentrating the available soluble salts in a modicum of water. The result was sufficiently promising to warrant a full line of experiments. At that time, no attention seemed to have been paid to the values of " gas-liquors." Nearly every gas-works in the United States wasted its wash-water in the sewers. The nitrogen in bituminous coals varies in quantity from 0.75 to 1.50 per cent. of the total weight. In the process of distillation in

Jan 1, 1887