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By J. W. Koger, R. E. Hurnrnel

QUENCHED, bcc p brass, P1, transforms to a mar-tensitic phase, when it is cooled below room temperature.' This transformation can be followed using resistance measurements since the resistivity of the martensitic phase is considerably larger than that of the parent phase, Fig. 1.' phillips3 first reported that, when Cu-Zn alloys containing between 37.0 and 39.0 wt pct Zn were quenched from the 0 region to room temperature, variable amounts of a phase could be observed depending on the mode of quenching. If the quench occurs very rapidly, the a phase forms by a "massive transformation". The resultant phase has the same composition as the high-temperature P phase from which it was formed. If the quench is less severe, the alloy is retained largely in the p form; however, some a is formed by precipitation. In this case, a contains more copper than the high-temperature 0 phase from which it has formed. The a phase most probably does not undergo a transformation in the temperature range where p transforms to low-temperature martensite. This can be deduced from the Eesistivity-temperature relation which is linear in this temperature range, Fig. 2. The stable a phase which is present along with R. E. HUMMEL is Assistant Professor, Department of Metallurgical and Materials Engineering, University of Florida, Gainesville, Fla. J. W. KOGER, Junior Member AIME, formerly with University of Florida, is now with Oak Ridge National Laboratory, Oak Ridge, Tenn. Manuscript submitted December 13, 1967. IMD.

Jan 1, 1969

By Frank Kneeland

SAFETY FIRST is a popular motto-most mining companies have adopted it. It is probable, however, that in the majority of cases it is only a motto and gets no further than the office stationery or the bulletin board at the mine's entrance. In but few industries is there employed a greater diversity of machinery and mechanical devices than in coal mining. The list ranges all the way from mechanical stokers to wood-working machinery and undercutters. Many of these devices, particularly those employed in wood working, are extremely dangerous. In 1913, 23 per cent. of all fatalities occurring in coal mining in the U. S. were caused by machinery of some sort or other. Although the forms of accidents occurring with mining machinery are legion, they generally arise from one or more of five causes: (a) Falls from ladders, platforms, etc.; (b) coming in contact with moving machines or parts thereof; (c) electric shocks; (d) failure of some machine part; (e) mismanipulation of valves, levers, switches or other hand-operated controlling devices. The steps which may be taken to prevent accidents from the above causes are almost as numerous as the accidents themselves. There is, and can be, no panacea for all mishaps, nor for any one class of accidents. There is no mathematical or other formula that will bring immunity under any set of conditions. Common sense is the only guide. The remedy for the first-named class of accidents is simple and generally effective-namely, make the staging, ladder, platform, or other support, abundantly strong to carry any possible weight that it may be called upon to bear; provide ample railings on platforms or runways, and non-slipping feet on movable ladders.

Jan 1, 1915

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

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, moreover, 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

By Arthur Knapp

The petroleum industry is confronted with the problem of conservalion. This is not a simple problem in view of a wide difference of opinion among authorities as to whether conservation is necessary and the specific direction that it should take. Many writers accuse the petroleum industry of wasting the natural resources of the country. Others link the consuming public with the industry in this waste. Let us define our terms; agree, if possible, on where and when waste occurs in connection with either the recovery or use of petroleum and select such plans for conservation as appear most practical. A plan for conserv3tion which appears to be logical today may not meet the problem tomorrow. The conservation of petroleum is closely linked with the advancement of marly arts and sciences and as these advance, the plan of conservation has to change. The need for conservation does not necessarily rest upon the elimination of waste. There is not necessarily a fixed connection between waste and conservation. Conservation may be necessary or desirable although there is no waste. Definitions Waste: Useless or unnecessary expenditure. Conservation: The preservation of the natural resources for economical use. Both definitions contain adjectives the interpretation of which is extremely difficult. It is the determination of what expenditures are "unnecessary" or what uses are "economical" that will require study and agreement. If one lets his automobile engine run in cold weather in order to keep it hot, it is difficult to measure that necessity. If an automobile is driven two blocks, when the driver is physically capable of walking, what is the measure of necessity. This question is in the realm of one of the oldest of sociological problems, "What is a luxury?"—a problem which has not been solved. The history of society indicates that the measure of a man's wealth has been the measure of necessity. What he can afford to buy without stinting himself in some other direction, is not a luxury to him and, if it fulfills his desires, may be considered his necessity.

Jan 1, 1927

By John A. Meech, J. G. Paterson

Activated carbon is a strong adsorbent for amyl xanthate, capable of removing from solution up to a quarter of its own weight in xanthate. In selective flotation system where depression is unstable, separation efficiency increases with activated carbon additions. The improvements observed are brought about by two mechanisms. First, by removing stripped and residual collector ions from solution, competition between depressant and xanthate is reduced and depression is stabilized. In addition, the texture of the froth phase at high pine oil concentrations is modified by activated carbon such that better drainage between the air bubbles takes place, alleviating the mechanical entrapment of depressed mineral particles. In treating a bulk copper/lead concentrate produced from GECO ore, selectively between galena and chalcopyrite is increased when activated carbon is used. Although the rate of flotation of galena is marginally lowered by activated carbon, a small extension in the duration of flotation allows the lead recovery to increase by 19% at the same recovery of copper. An addition rate of 0.75 kg/ton (1.5 lb/st) of bulk concentrate is suggested as optimum from this testwork. However, the actual level used in the mill is dependent upon the residual concentrations of collector and frother in the bulk concentrate pulp.

Jan 1, 1979

By Charles Pack

DIE castings may be defined as metal castings made by forcing molten metal, under pressure, into a metallic mold or die. It is necessary to keep this definition in mind to avoid confusing this process with other permanent-mold casting processes. The fundamental principles of the process have been known and practised many years. The simplest application is embodied in the modern linotype machine in which molten metal (usually tin-lead alloy) is forced under pressure into a metallic mold. The pressure is derived from a piston and cylinder immersed in the molten metal. Progress in the art of die casting may conveniently be divided into threee groups: Machine for imparting pressure to the metal, material for the die or mold, casting alloys. CASTING MACHINES The problem of delivering molten metal under pressure into a die is comparatively simple, when dealing with low-fusing-point alloys, as the alloys of lead and tin, but it is much more complicated when dealing with metals of higher fusing points, such as the alloys of zinc, aluminum, and copper. Although the art of die casting is comparatively new and, to a large extent, unknown, the records of the patent office are replete with patents on the subject. Fig. 1 shows the Underwood machine patented in 1902; this is probably one of the first machines designed for the production of commercial die castings. The relation of this machine to the linotype casting machine is clearly. apparent. A cylinder and piston are immersed in the molten metal, the application of power to this piston forcing the molten metal, under pressure, into the mold or die. The Doehler machine, Fig. 2, patented in 1907, is based on the same general principles. This machine is used to a large extent at the present time, throughout the United States, for the production of zinc, tin, and lead alloy die castings.

Jan 2, 1919

J. B. MCGRAW, New York, N. Y. (written discussion*).-In Mr. Burke Baker's description of the process of the American Briquet Co., he speaks only of the attractive features, but every process which uses a compound or emulsified binder has certain undesirable features which must be considered. In making an emulsion, the success of which depends upon the introduction of the various ingredients at certain fixed temperatures and the complete intermixing of a soluble solution with an oil which has absolutely no affinity for it, considerable difficulty is found in keeping the various factors in strict accordance with the formula. To serve its purpose properly or, in other words, to be right for easy mixing with the coal, it should be of a certain predetermined density. Among the controlling factors of this ate the proportion of moisture contained and the temperature of the oil when introduced. If the latter is higher than intended, a greater proportion of moisture will be evaporated than is proper, and if the oil is not sufficiently hot the process of emulsification is retarded. These various factors can be controlled with more or less certainty where working in a laboratory or in a small experimental way, but when it is attempted on a large commercial scale, certain obstacles not otherwise apparent are likely to be encountered.

Jan 5, 1918

By Bailey Willis, George Otis Smith

I. Summary of General Features. Location.—The Clealum iron-ore deposits occur on Clealum river, a tributary of the Yakima river; in the eastern spurs of the Cascade range, Washington.† Mount Stuart, 9470 feet in altitude, is a dominant peak of the district, which will therefore be referred to as the Mount Stuart district. By way of the valley and cañon of the Clealum, the ores are 18 miles from Roslyn, the colliery-town, which is reached by a short branch from the Northern Pacific Railroad. Where they occur the valley has an elevation of 2900 to 8000 feet above sea; that of the end of the branch railroad at Ronald is 2345 feet. The grade of the valley from near Ronald to the junction of the Clealum and Salmon Lasac rivers, 144 miles, is 20 feet per mile; thence to the iron-ores it is 130 feet per mile, through a cañon 241/2 miles long. Abreast of the deposits the western wall of the valley is formed by precipices of sandstone; the eastern slope is comparatively gentle, being cut in easily eroded

Jan 1, 1901

By Yang Tsang Woo

The method of making coke that has been adopted at the Kaiping and other collieries in northern China resembles, to some extent, the familiar bee-hive oven process of the United States, except that a kiln with permanent sides is used instead of a closed oven, and the products of combustion are drawn off at the bottom. In building coke-kilns in China, two circular holes, 8 ft. 6 in. in diameter at the bottom and 13 ft. in diameter at the top, are excavated in the ground, and connected at the bottom by a flue, as shown in Figs. 1 and 2. The sides and bottom of the kiln are lined with fire-bricks, and covered with a lager of fireclay, and a rectangular opening, 6 in. by 8 in., connects the bottom of each kiln with the main flue. Around the edge of the hole, and overlapping the lining, is a wall of fire-brick extending 2 ft. 6 in. above the level of the ground. An open space 5 ft. wide is left in this wall, through which the coal is carried into the kiln and the resultant coke removed. This space, of course, is bricked up during the time that the coking-operation is being carried on. The wall is pierced with nine flue-openings uniformly placed around the circumference, each interverliilg space in the wall being strengthened with a brick buttress, as is shown in Figs. 2 and 4. The floor of the kiln, as well as the main flue, is lined with fire-brick. Before charging the coal, it is first placed in shallow bamboo sieves, 2 ft. in diameter, and immersed in a trough 10 ft. long, and 3 ft. wide, fed with pit-water, in which it is washed by hand. Fig. 3 shows the manner in which the washing is done. From 25 tons of good "dust" coal, 22.5 tons of washed coal are obtained. When ready to charge the coal into the kiln, a temporary cone-shaped flue of fire-wood and lump coal is first built to a

Jan 1, 1906

By Craig R. Barrett, Oleg D. Sherby

The creep characteristics of four pure metals with widely Varying stacking-fault energies (silver, copper, nickel, and aluminum) were evaluated above 0.5Tm. Creep tests were performed under conditions of constant atomic diffusivity and constant stress over the elaslic modulus. The sleady-state creep rate, Es, was found to he a funclion of the THE most common empirical representation of the steady-state creep rate, Es, at high temperatures and intermediate stresses is of the form where a is the applied stress, E is an elastic constant, A and n are constants (n is typically stacking-fault energ, y, such that Es is proportional to y3,5. In addition, it was uncovered that the primary creep strain and the strain to fracture increased with increasing y, and that the ratio of initial to steady-state creep rate decreased with increasing y. about 5), Q is the activation energy for creep (usually equal to that for self-diffusion), and kT has its usual meaning. sherbyl and McLean and ale' have used this expression to correlate creep data for a number of pure metals. An interesting aspect of Eq. [I] is the absence of any dependence on the stacking-fault energy. While most creep data seem to obey the stress and temperature dependence predicted by Eq. [I], when data for several metals are put on a master plot they do not fall on a common line but form a band. The width of this band corresponds to a variation in Es of 102 to l03. sherbyl attempted to explain this band by assuming that a grain-size effect was present which led to the observed variation. On the other hand, Felt-

Jan 1, 1965

By J. W. Dougherty, J. M. Douglas

THE Hollinger gold mine is in the Porcupine mining division, District of Cochrane, in the northern part of the Province of Ontario. The adjacent town of Timmins, with a population of 25,119, lies 490 miles by railway north of the city of Toronto. GEOLOGY The property is situated on the northwest limb of a major syncline, which pitches northeast at approximately 50°. The principal rocks of the Hollinger area are of pre-Cambrian age and consist of altered, schistose, Keewatin lava flows intruded by stocks of schistose, quartzfeldspar porphyry generally assigned to the Algoman period. The structure of the Keewatin series is extremely complex as a result of close folding and some faulting. The schistosity, trending north 70° east and dipping steeply to the southeast, is most highly developed along a subsidiary anticline in which the major porphyry bodies occur. The ore bodies, which exhibit three principal structures, consist of quartz veins and associated pyritized wall rock. Some lodes are composed of en echelon veins, others exhibit a main quartz body with branching stringers and a third consists of a single definite lead. Gold, in a coarse visible form, may be confined to quartz in some ore bodies but in others it is finely divided and is found not only in quartz but also associated with pyrite in the adjacent wall rock. In many veins the distribution of gold is such that there are several ore sections, separated by areas of low-grade material, in the same vein although its physical appearance remains unchanged. The veins form a very complex pattern in an ore zone which in places attains a length of 6000 ft. and a width of 4000 ft. They are most abundant in the Keewatin lavas in the neighborhood of the porphyry bodies. Few of the veins are persistent for long distances, though some

Jan 1, 1940

By G. M. Schwartz, J. N. Gundersen

John W. Gruner (Professor Emeritus, College of Science, Literature, and the Arts, Dept. of Geology, University of Minnesota, Minneapolis) — It is surprising that two men as well acquainted with the taconite rocks of the Mesabi District as Drs. J. N. Gundersen and G. M. Schwartz should have concluded that the taconite of the Eastern Mesabi before the intrusion of the Duluth gabbro consisted largely of quartz and magnetite. These minerals were "locally reconstituted" into "a wide variety of silicate mineral assemblages" by the gabbro. It is well known, of course, that the silicate mineralogy of the Eastern Mesabi ('about 14 miles in length) is quite different from that of the Main Mesabi which is over 60 miles long. The change from one to the other is abrupt and cannot be attributed to any other cause than the thermal effects of the gabbro. Are we to assume or believe that the taconite of the Eastern Mesabi was radically different from that of the Main range before the gabbro metamorphosed it?

Jan 1, 1962

By D. Watson, T. J. N. Grainger-Allan

A technique for studying the mechanism of the froth flotation process in which continuous froth removal does not take place but, instead, an equilibrium is reached between froth and pulp is described. A flotation cell, specially designed to facilitate equilibration, and froth and pulp sampling procedures are described. The main advantage of the technique is that the ability to measure the steady-state froth height allows froth-stability effects to be separated from pulp-process effects. In the flotation of hematite front quartz, linear relationships are found between airflow rate and froth height and between airflow rate and the ratio at equilibrium of mass of values in froth to mass of values in the pulp. A simple mechanistic interpretation of these results is given. It is suggested that froth-stability effects may play a more important role than hitherto allowed. In particular, the way in which concentration and size distribution of gangue particles may affect overall flotation rate is shown.

Jan 1, 1975

By Dennis A. Clark, Brent Larsson

Tunnelling today is a lot more than drilling and blasting. The developments in drilling and blasting technique have made it pos¬sible to save costs both by increasing the advance per round and optimizing the demands on the final contour. Increasing the hole depth by using longer feeds and bigger dril¬ling rigs make the drilling time shorter compared to the set up time. It is important that the deeper holes are followed up by using a suitable cut. The most common cut in Sweden today is a parallel hole cut with one or more large holes; with a diameter corresponding to the hole depth and wanted advance per round. It is often specified that smooth blasting is to be carried out with a specific drill hole spacing. It is extremely rare, however, for specifications to be issued concerning the alignment of the raw of holes closest to the contour holes. It is very easy to ruin the effect of smooth blasting altogether by firing the rest of the round carelessly with an excessively high charge distribution. The drilling and blasting of the contour holes and the line of holes closest to the contour holes is therefore an extremely important part of any underground work. Accuracy and care in connection with the drilling of contour holes is also extremely important since it is possible to reduce the amount of overbreak, the result being more rapid mucking out, smoother and more durable surfaces and also less consumption of concrete for lining purposes.

Jan 1, 1983

By T. P. Harrington, P. G. Doctor, K. A. Prisbrey

Crushing and grinding ore consumes so much energy that it represents a major component of total processing costs. While it has been estimated that only about 0.6% of the total energy expended in grinding is actually used to create new surfaces, accurate measurement of this quantity is difficult. If energy expended in crushing and grinding could be more directly measured, alternatives for increasing efficiency of the processes could be evaluated more effectively. Since the energy intensity associated with rock fracture is related to fracture sonority, it should be possible to use this sound (acoustic emission) to measure the actual energy expended. However, it is difficult to apply this approach because the mill environment is so noisy. To make the approach practical, a method for differentiating acoustic emissions caused by rock fracture from those caused by extraneous noises must be found. Pattern recognition analysis may provide such a method. This paper presents the results of pattern recognition analysis to make two types of differentiations: acoustic emissions caused by crushing two types of minerals (quartz and chrysocolla) and those caused by two extraneous noise sources, and acoustic emissions produced by each mineral.

Jan 1, 1982

By C. Schlumberger, M. Schlumberger

The object of this paper is to clarify the idea, so important when exploring by potential methods, of the depth of investigation attainable by electrical measurements. After defining, with some precision, .the term "depth of investigation'' in geophysics, the authors show how it is possible to regulate this depth in potential methods and to obtain an 'electrical drilling" from surface observations. They consider also the difficulties encountered in deep measurements and indicate how it is possible to reach greater depths than those having an industrial interest. Depth of Investigation The term, depth of investigation, in its general sense, is easily understood. For instance, a driller who can pull cores from a depth of 2000 m. is capable of working, with accuracy, to that depth. By means of a properly placed drill, he may locate an orebody at a depth of 1999 m., however small this orebody may be. On the contrary, the term as used in geophysics requires precise elaboration. As a matter of fact, no geophysical method, irrespective of the physical property studied (density, magnetic permeability, conductivity), can discover a very small body at a great depth because, in practice, the physical parameter upon which such a geophysical method is based is never regular enough, throughout the ground, to distinguish the feeble anomaly caused by the small, deep-lying body from the numerous anomalies due to irregularities of the encasing terrains. Aside from this question of the ratio between the size of the body being hunted for and its depth of burial, a second factor plays its role in the possible depth of investigation; that is the difference, for the parameter under consideration, between the body and its surrounding material. The greater this difference, and the more homogeneous the encasing terrains, the greater is the possible depth of investigation. This being generally established for all geophysical methods, it is possible to distinguish two main classes of these methods, from this same point of view

Jan 1, 1932

By A. P. Anderson, J. H. Jensen, W. E. Breckoff

Bromine is the intermediate member of the halogen family of elements between iodine, a solid, and chlorine, a gas. The name is derived from the Greek "bromos," meaning stench. Bromine is the only nonmetallic element that is liquid at room temperatures with a melting point of -7.2° C and a boiling point of 58.78º C. Reddish brown in color, it dissolves easily in water to yield a red solution. Bromine volatilizes at ordinary temperatures to a red vapor that is very irritating to the eyes, nose, and throat. Density of the liquid is 3.12 and gas weighs 7.59 gpl at standard conditions. As the element is highly active, it exists in nature only as bromide compounds. Bromine was discovered by Antoine Jerome Balard in seawater bitterns in 1826 and first prepared in quantity in 1860. Distribution Bromine is widely distributed in nature and compounds occur in solution in natural brines, in seawater, saline lakes, oil and gas well brines, and in evaporite chloride minerals. The concentration of bromine salts ranges from 60-65 ppm in seawater to several thousand ppm in oil well brines and saline lakes. The distribution of bromine in marine evaporite minerals and in the solutions from which they crystallized was determined many years ago by H. E. Boeke (1908). Theoretical aspects regarding the geochemistry of bromine have been published in numerous papers (Raup and Mite, 1969). Bromine occurs in solid solution in carnallite and sylvite associated in potash deposits; in halite in salt beds; salt in oil shales; and in trona deposits. Its presence is useful as a guide in geochemical exploration. The analysis of small amounts of bromides in the presence of large amounts of chlorides is discussed by W. Schwerdtner (1963). Manganese, iron, and iodine may interfere with the determination. Other analytical methods are discussed at length in the literature (Stenger and Atchison, 1964). Sources and Reserves The sources and reserves of bromine, given in Table 1, appear ample to meet present and foreseeable requirements in all producing countries. With the occurrence of bromine salts in seawater and other brines, the potential for bromine production is worldwide. It has been estimated that 99% of all commercially recoverable bromine is in the ocean. However, actual subterranean brines having a higher bromine content than seawater will continue to be the preferred sources of bromine for the foreseeable future. [ ]

Jan 1, 1983

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 Graham Bright

Before the arrival of central-station power, all coal and metal mines generated their own power and, in many cases, these isolated power plants gave a fair continuity of service. In coal mines that produce considerable gas, it is essential that power be available at all times for operating the ventilating fan and the hoist, if the mine is of the shaft type. In the case of an isolated power plant, if trouble should develop with the fan the men can be hoisted quickly when the mine is of the shaft type. On the other hand, if trouble develops with the hoist, the fan can be kept in operation, and there will be no necessity of haste in getting the men from the mine. Now that central-station power is being used so extensively for mine service, the continuity of service with gaseous mines is very important. : Inherently, the central station is much more reliable than any isolated plant, but trouble may occur on the transmission lines which may prevent the transmission of power for a considerable time. : Some mines have kept their steam equipment intact and ready for operation in case the purchased power should fail. This is expensive procedure, for the boiler plant must be fired at all times so that the emergency power will be quickly available. In a number of instances, gasoline-engine driven generators have been installed to furnish emergency power for the service hoist. As most service hoists are of the alternating-current type, the generator of the gasoline-engine driven set is usually of the a.c. type and is arranged to drive the service hoist motor at full speed, or an extra motor that can be thrown into gear on either the main or service hoist and the hoist operated at a greatly reduced speed. This arrangement is used because it is difficult and expensive to obtain and install large gasoline-engine driven units. The author has recently developed a plan by which the main hoist and the fan can both be operated at reduced speeds, in case of loss of power from a central-station power system. In this plan a gasoline-engine

Jan 1, 1923