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By Howard Scott

The great advances made in mechanical engineering during recent years through the use of alloy steels, as illustrated by the development of the airplane and automobile, may be ascribed primarily to the application of nickel as an alloying element. The ternary system iron-carbon-nickel has a wide industrial application and forms, further, thefundamental basis of the even greater class of the widely used quarternary steels such as nickel-chromium, nickel-silicon, and nickel-vanadium. As is not uncommon with such cases of virile growth in an industry, the application of the alloy steel in a largely empirical manner has outstripped its scientific development so that a fertile field for metallographic research still remains. In this field, the basic nickel steels require first consideration and are the subject of the present investigation, which is offered as a preliminary to the study of the more complex alloys of industrial importance Of the principal tools of metallography—microscopic examination, determination of mechanical properties, and thermal analysis—the last has developed much more slowly in its application to industrial needs so that the situation often exists that heat treatment operations are based on empirically determined temperatures; that is, temperatures deterrnincd without regard to the actual transformation characteristics of the alloy. This situation is undesirable as there is no uniform standard for comparison of results. It is due, outside the usual difficulties involved in temperature measurements, to the pioneer character of much of the published work; to the lack of definiteness of the Ac, transformation,1 particularly in low-carbon steels; to the failure to define operating conditions completely; and to the paucity of information correlating thermal characteristics with results of heat treatment.

Jan 1, 1922

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Jan 1, 1907

By J. W. Spretnak

It is well-established that decohesions occurring at the interface of the matrix and rigid inclusions and second-phase particles are prime causes of ductile fracture initiation. It is not clear, however, how these decohesions occur. The idea that the interface bond is broken in tension is not particularly attractive when one considers the strength of such interfaces and the fact that plastic flow is not restricted under conditions of continuing flow required to initiate and propagate ductile fracture. A suggestion as to the mechanism of decohesion arises if one takes the position that, as the dislocation density increases with plastic flow and reaches some critical range of density, the phenomenon of flow can be regarded as fluidlike instead of the crystallographic motion of dislocations. As the spacing between dislocations decreases, the matrix becomes increasingly disordered in terms of loss of periodicity. At some critical degree of reduction of the periodicity, it is suggested that flow can be regarded as hydrodynamic, rather than crystallographic. Such a state has been referred to by rheologists as the "plasticized state", or the "fourth state of matter", between the liquid and solid state. A similar argument pertains qualitatively with the increase in equilibrium vacancy concentration as the temperature approaches the melting point. Taking the viewpoint that at larger strains the flow may become hydrodynamic in nature, a mechanism of decohesion is suggested. A well-known phenomenon in boundary-layer flow is that of "separation" locally of the boundary layer from the substrate.' Under certain conditions, the flow in the immediate neighborhood of the substrate becomes reversed, causing the boundary layer to separate from it. The exact condition for separation is that the velocity gradient normal to the substrate vanishes there, or It is of interest that blunt particles such as spheres and circular cylinders are most likely to give rise to separations because of unfavorable pressure distributions behind them. The source cited gives solutions for positions of separations for various geometries. In principle, such separations can also take place when metal is flowing over a "dead zone" of stagnant metal. This may explain the initiation of fracture at the elastic-plastic boundaries of plastic enclaves under a notch.

Jan 1, 1967

By E. L. Estabrook

THE production of crude oil in Wyoming rose to 44,290,010 bbl. in 1923 and declined, during 1924, to 39,295,030 bbl., a decrease of about 11 per cent. The Salt Creek field supplies 75 to 80 per cent. of the production. Pipeline runs from the Salt Creek field reached a maximum in November, 1923, at a daily average for the month of 116,437 barrels. During 1924, the gas pressure in Salt Creek has declined rapidly and the production dropped to about 60,000 bbl. per day. Part of 'the decline during the last few months was due to lack of power to pump the wells. The electric-power plant of the Midwest Refining Co. did not begin to deliver current until the middle of December, by which time several hundred wells were off production. The cold snap in December, which brought, the temperature down to 30° below zero on the 17th, tied up operations almost completely and the average production for the month was only 49,545 barrels. As more wells are being pumped and the number of dead wells reduced, the production is rising and was up to 61,000 bbl. during the last week of January. A further increase is expected as the weather becomes warmer. The production of Salt Creek, by months, during 1924 is given in Table 1. TABLE 1.-Total Monthly Production, Average Daily Production and Number of Producing Wells in Salt Creek during 1924 TOTAL PRODUCTION, DAILY AVERAGE, NUMBER OF MONTH BARRELS BARRELS WELLS January 3,523,647.40 113,666.05 919 February 3,074,916.67 106,031.61 929 March 2,977,095.14 96,035.32 950 April 2,811,110.22 93,703.67 987 May 2,858,842.04 92,220.71 1,024 June 2,649,752.57 88,325,09 1,092 July : 2,697,829.36 87,026.75 1,153 August 2,624,371.84 84,657.15 1,213 September 2,281,219.04 76,040.64 1,274 October 2,073,961.42 67,000.84 1,313 November 1,722,050.09 57,401.67 ~ 1,335 December 1,535,903.78 49,545.28 1,352 Total 30,831,699.57 84,239.61 1,352

Jan 3, 1925

By W. P. Haseman

The well method of producing oil and gas is universally used in the development and operation of oil and gas properties. It consists essentially in the spacing of a number of wells on a given tract, and in drilling and operating them in accordance with established practices. The method is based on a fundamental energy principle. This principle governs the state and the change of state of fluids or fluid mixtures confined under pressure within a porous and permeable reservoir in such a way as to direct a flow from the reservoir into and out of a drilled well with a reduction of potential energy. The application of the well method of producing oil has given data which prove that the total yield of oil from a reservoir through wells is, in general, only a small fractional part of the total oil that is contained in the reservoir. It is generally recognized that a spacing of one well to each 160-acre tract of any good oil pool is too wide. However, one well to this 160-acre tract will yield a large quantity of oil and in time will dissipate most, if not all, of the potential energy that was originally stored and retained in the fluids by pressure. Two wells spaced and drilled on this 160-acre tract would yield approximately twice the quantity of oil, while four wells would yield approximately four times the oil. A well spacing is soon reached, with the addition of wells to this 160-acre tract, in which the drainage interference of offset wells will materially affect the yield of oil per well. The increased yield of oil, therefore, is not directly proportional to the added number of wells but the increased costs of development are directly proportional to the added number of wells. It is evident that while an added number of wells to this 160-acre tract yields an increased quantity of oil, there is an economic limit to the number of wells to be added. The yield of oil and the costs of development and operation are of such a nature, and are so related, that

Jan 1, 1930

By Prof John E. Church

It is a well-known fact that under similar conditions a ton of pig iron can be made from any ore with less fuel when charcoal is used than when coke or anthracite is employed for heating. The cause of this superiority is entirely undiscovered, and no explanation has yet been offered which has won even temporary acceptance. Such as they are the hypotheses heretofore presented are of two general kinds, and they come from those two divisions of the working force which are so often antagonistic in all professions, the scientific and the practical men. The theory of the scientific men is drawn from the chemical reactions which are known to go on in the furnace, and it is well expressed in a recent paper by Prof. Akerman, of the Stockholm (Sweden) School of Mines. It makes the superiority of charcoal as a fuel in the blast furnace to depend upon its quick and thorough reduction of carbonic acid. This property belongs to charcoal in virtue of its porous structure. Its cells have a diameter of only one twenty-four hundredth of an inch, and one grain of charcoal has been computed to have a surface of two and four-tenths square feet. According to the theory in question, carbonic acid is formed by the first impact of the air upon the fuel; but in charcoal furnaces the acid is immediately reduced to oxide by taking the necessary amount of carbon into combination, and the gas reaches its highest reducing power even in the near vicinity of the tuyeres. Coke, being harder, does not produce so strong a reducing gas in that part of the furnace. Carbonic acid is formed as in the case of charcoal, and remains longer before its reduction to oxide is completed. Anthracite is the

Jan 1, 1879

By O. G. Bell

While all of the Southwest Texas fields lie within the Gulf Coastal Plain this area may be divided into three subdivisions—the Coastal Plain zone proper, the Reynosa Escarpment zone, and the interior zone. The Coastal zone includes that strip adjacent to the Gulf of Mexico and . extending inland for a distance of about 60 miles and includes the Palo Blanco, Palangana, Piedras Pintas, Kingsville, Agua Dulce, Saxet, White Point and Refugio fields. The Reynosa Escarpment zone includes a Pliocene overlap over older Tertiary sediments lying west of the Coastal zone. The western margin of the Reynosa formation forms a more or less well-defined westward facing escarpment with which the so-called Reynosa Escarpment fields are indirectly related. These fields include those in eastern Zapata, eastern Webb, western Jim Hogg, western Duval, McMullen, Live Oak, Bee, Goliad and Victoria counties. The interior zone includes these fields west of the Reynosa Escarpment which are not in any way related to it and are on separate types of structure. Production data by fields and wells are shown in Table 1. Roma.—During 1928 the Texas Co. completed two small gas wells at 198 ft. on the Roma Structure near the town of Roma on the Rio Grande in Starr County. This gas is of no commercial importance but was used for fuel in drilling other deep tests on this structure. Three dry holes ranging from 3600 to 4200 ft. were drilled; then their No. 4 Guerra, the fourth deep test, was completed during December as a small producer of 37" Bé. oil from a sand at 3560 to 3590 ft. No production was marketed during December but arrangements were being made to handle the output from this well during 1930. This is the first commercial producer in Starr County. Driscoll.—In 1929, Robert Driscoll discovered gas on his Santa Rosalia Ranch in Duval County while drilling water wells. Two sands were developed, one at 2400 ft. and another at 2936 ft. and several gas wells were completed in each, ranging in volume from 15,000,000 to 40,000,000 cu. ft. and in reservoir pressure from 500 to 1,000 Ib. Early in January of 1929, Mr. Driscoll's No. 14 Fee was completed as a 50-bbl. oil producer at 2894 ft. Two other oil producers were completed early in 1929. Mr. Driscoll's death early in the year curtailed develop-

Jan 1, 1930

By W. L. Chu

It was observed that chromized coatings on low carbon steel could be embrittled by cooling slowly through the 475°C range. A higher chromium coating was more susceptible to embrittlement than a lower chromium coating. Coating structure and composition could be correlated with the chromizing process and prior carbon content of the steel. IT was recently observed that during the fabrication of rectangular tubings made with chromized thin gage 1010 steel, a high percentage of these parts were fractured readily in a brittle manner under the light impact-forming load employed. Ensuing investigation indicated the cause for such brittle failures to be the so-called 475°C embrittlement of the chromized coatings. The experimental work and results are briefly reported. Rectangular tube sections of normalized AISI C1010 steel, which had a cross-section of 0.5x1.5 in. and a wall thickness of 0.030 in., were chromized to yield coatings having several ranges of thickness, varying from 0.0005 to 0.002 in. Essentially, the chromizing process is similar to that described by Samuel and Lockington,' which consists of heating the parts in a sealed container at about 955°C for 4 hr in intimate contact with a chromizing mixture* samples in a hydraulic press, and the other employed a simple beam bending test of the flat sides of the tubing walls. Neither, however, was able to differentiate the relative brittleness of samples known to include both the brittle and tough types, since the impact-brittle samples were found to deform readily in a manner similar to the tough ones. Both the tough and brittle samples were studied by reflection microscopy. Observation showed that the microstructures of the steel cores were similar in content and distribution of inclusions as well as in the ferritic grain size. Results of Filar micrometer measurements showed that coating thicknesses+ of the brittle samples averaged 0.0007 in., whereas those of the tough samples averaged 0.0016 in. The micrographs of Fig. 2 illustrate the structural differences between coatings of both types of samples. By dissolving the steel cores in nitric acid, coatings of both the brittle and tough samples were isolated. Simple bending tests showed that coatings of the brittle samples cracked readily at about 90" bend, whereas those of the tough samples could be bent nearly 180° without cracking. The coatings as well as the steel cores were analyzed for carbon and

Jan 1, 1956

By D. B. Dowling

The interest which has been aroused in prospecting for oil in the foothills of southern Alberta, and in the oil possibilities of the known gas fields situated in the less-disturbed areas, called for a much closer examination of the structure, thickness, and composition of the underlying rocks of the region than had hitherto been made. The areal geology of the larger part of the great plains was outlined by Dawson, McConnell, and Tyrrell, between 1881 and 1885. The foothill area was not critically examined at that time, owing to the time which would have been required for its proper study and the difficulty that was found in recognizing in the foothills the divisions which had been adopted in the mapping of the formations of the plains. This was due in great measure to the paucity of exposures in continuous sections of the lower divisions of the Upper Cretaceous. Since the pioneer work on the plains was published, the beds which form continuations south into Montana have been critically examined, The Canadian beds arch over the end of a flat anticline which rises to the south; and two sections in Montana, one on each side of the anticline, help to explain some of the difficulties previously encountered in the mapping of the measures found in the foothills. The index map, Fig. 1, shows the area studied, and its relation to southeastern Alberta, and to Montana. Problems of Correlation The principal difficulty experienced in correlation was in connection with the measures known as the Montana group. The beds of this group did not seem to agree in the two Montana sections. They showed the same differences to some extent as are encountered in comparing the foothill measures with those of the plains. The Montana group in Dakota and Manitoba consists of a series of shales of marine origin. In the eastern Montana section two sandstone members appear, leaving a shale member at the top and another

Jan 1, 1916

By Howard Scott

The great advances made in mechanical engineering during recent years through the use of alloy steels, as illustrated by the development of the airplane and automobile, may be ascribed primarily to the application of nickel as an alloying element. The ternary system iron-carbon-nickel has a wide industrial application and forms, further, thefundamental basis of the even greater class of the widely used quarternary steels such as nickel-chromium, nickel-silicon, and nickel-vanadium. As is not uncommon with such cases of virile growth in an industry, the application of the alloy steel in a largely empirical manner has outstripped its scientific development so that a fertile field for metallographic research still remains. In this field, the basic nickel steels require first consideration and are the subject of the present investigation, which is offered as a preliminary to the study of the more complex alloys of industrial importance Of the principal tools of metallography—microscopic examination, determination of mechanical properties, and thermal analysis—the last has developed much more slowly in its application to industrial needs so that the situation often exists that heat treatment operations are based on empirically determined temperatures; that is, temperatures deterrnincd without regard to the actual transformation characteristics of the alloy. This situation is undesirable as there is no uniform standard for comparison of results. It is due, outside the usual difficulties involved in temperature measurements, to the pioneer character of much of the published work; to the lack of definiteness of the Ac, transformation,1 particularly in low-carbon steels; to the failure to define operating conditions completely; and to the paucity of information correlating thermal characteristics with results of heat treatment.

Jan 1, 1922

By W. A. Lang, K. C. Gilbart, E. Stansfield

It has long been known that coal is unstable and oxidizes in air, even at ordinary atmospheric temperatures; also, that such oxidation affects the analysis of coal. Nevertheless little or no precaution is taken to prevent oxidation in the ordinary methods of analysis, and the possibility of error due to oxidation is sometimes ignored even in researches on coal. Although the general nature of coal oxidation is well known, and many workers have made careful studies of the rate of oxidation of different types of coal exposed to oxygen at different temperatures, yet the amount of oxidation coals undergo in the ordinary process of analysis, and its influence on the determined analysis, is not well known, and the published data are widely scattered through the literature. This paper is a collection, from this laboratory, of data that bear on the subject, together with a brief summary of three methods employed here to evaluate the oxidizabil-ity of coal. The post-Carboniferous coals of Alberta range all the way from anthracite down to lignite. As some of them are notably susceptible to oxidation, the necessity for care was early forced upon our attention, and oxidation has been reduced either by the removal of air with a vacuum pump or by the displacement of air with natural gas (methane). The two routine analytical operations most liable to involve oxidation are the preliminary, partial drying of the crushed coal (called air-drying) and the determination of moisture. The first is a prolonged operation on coarse coal at ordinary temperatures, and the second a short treatment on powdered coal at higher temperatures. Oxidation also occurs in coal samples stored in ordinary sample bottles. In order to gain information for this study, determinations were recently carried out on the same samples in air, in natural gas, and in vacuo. Sixteen coals were tested; three would be classed in the United States as coking bituminous coals, two as noncoking, nonslacking, bituminous coals, and the rest as subbituminous. Table 1 gives typical analyses of these coals as mined.

Jan 1, 1934

Discussion of the paper of Dorsey A. Lyon and Robert M. Keeney, presented at the Butte meeting, August, 1913, and printed in Bulletin No. 80, August, 1913, pp. 2117 to 2149. C. D. WOODWARD, Butte, Mont.:-We constructed a small blast furnace, and used first carbon electrodes and an alternating current of about 50 to 75 volts. We were able to smelt the material which was fed to the furnace, but we did not carry on experiments far enough to see just exactly what the power consumption was and compare it with the amount of material treated. We found that the blast seemed to help materially in reducing our charge and cutting down our power consumption. There were several other experiments tried at the time, and I do not call to mind now just what they were. We were trying to do away with the carbon electrode and replace it with an iron one, and it also seems to me we tried to use the ore for an electrode; but I believe that the electric furnace in the reducing end is simply a question of British thermal units per kilowatt-hour compared with British thermal units in a pound of coke. Now, if a pound of coke costs us 0.5 c. and a kilowatt-hour costs us in the neighborhood of 1.5 c., I think there is a big advantage in using coke instead of the electrical current for copper reducing. We tried steam, and a number of other methods, to throw copper down, but it has been some time ago and I am not very familiar with them now. The outlook of the experiments did not seem to be very promising, and we took it more as a thermal problem than an electrical one. PROF. JOSEPH W. RICHARDS, South Bethlehem, Pa.:-Mr. Woodward has spoken of the question as a thermal problem. I would call attention to the fact that electric furnaces usually utilize the heat of the electric current at from four to ten times the efficiency with which the heat generated by fuel is utilized; so it will not do simply to compare by thermal units generated. Your total thermal units may cost much less from coke than from electricity, yet you will find the electrically generated thermal units utilized in a properly designed furnace from three to ten times more efficiently than in the combustion furnace. You must make that allowance is comparing the cost of thermal units generated electrically and thermal units from coke.

Jan 11, 1913

By Edward M. Weiss

THE emphasis in some political quarters on hemispheric unity and defense indicates Latin American mineral resources should be more extensively developed. However, United States mining companies have, in many instances, been discouraged by the laws of southern neighbors. At the same time, some of the countries have liberalized their mining laws in an effort to attract investments from the United States. The resultant confusion has been detrimental to all concerned. Ownership of Mineral Deposits Examination of the mining codes of Latin American countries shows that, without exception, governments reserve the right of direct ownership of all mineral resources. Ownership can be divided between the Feredal Government and the states or among the Federal Government, the states, and private individuals. However, in the majority of the nations constitutional authority vests all mineral rights solely in the Federal Government. Mexico is the only country that has expressed Federal ownership as imprescriptible; the other republics have not defined the exact significance of government ownership. The implication derived from the general economic and political climate is that all mineral resources are ultimately to be regarded as a national heritage. Whether a concession granted to an individual or corporation carries any right of private property is shaded with a variety of meanings. The exceptions at one extreme are Argentina and Bolivia, whose laws state explicitly that a concession granted to a juridical person is an act of the state, and the land becomes the private property of the individual, and the concessions constitute real property. However, in Mexico mining concessions or grants do not create rights of fee-simple ownership. The concession only conveys the exclusive right to explore, develop, and work the deposits. The mining property remains the property of the state. In some instances exploitation concessions represent a compromise between private and government ownership. In Honduras the period granted to a mining enterprise is fixed at 90 years. At the end of that time, the enterprise and all installations revert to the state without compensation.

Jan 1, 1952

By C. P. Parsons

To properly account for the various characteristics of drilling muds obtained in different areas and geological horizons, it is necessary to study the composition of the mud from a chemical and physical standpoint as determined by the proportions and activities of the various solid contituents that are present in various states of division. Briefly summarized, science teaches that there are three states of division into which these solid constituents or particles may be grouped: namely, the suspended state, the individual particles of which are known as suspensoids; the colloidal state, in which the individual particles are termed colloids; and the crystalloidal state, wherein the individual particles are held in true solution and are termed crystalloids. The suspended state is one wherein the particles are fairly large and are present as molecular complexes, having none of the properties of colloids or crystalloids. Since matter varies in physical character and in chemical activities with its state of division, these coarser suspensoids do not themselves materially affect the physical or chemical properties of the solution in which they are suspended. On the other hand, they are distinctly detrimental in drilling muds and it is desirable that they be removed. Under the general classification of suspensoids are included sand, gravel and cuttings which contribute nothing to the colloidal stability or other desirable properties of the drilling fluid. As the state of division approaches but does not reach a molecular simplification, the term "colloidal state" is used in describing this condition. The colloidal state arises when one form of matter is in a very fine state of division and is distributed through a second phase. The material in the finely divided state is called the dispersed phase, while the liquid in which it is dispersed is called the dispersive phase. These particles of matter are in a colloidal state and will not settle out from the dispersive phase so long as colloidal conditions are stable. Moreover, they exhibit the property of having an oscillating movement around a central position in solution (the Brownian movement). In the third state of division, the crystalloidal state, the individual particles are held in true solution and are usually present as single molecules or ions. In a drilling fluid the water content of the fluid contains

Jan 1, 1931

By William P. Blake

The occurrence and distribution of phosphorus is one of the most important questions with which the steel-maker has to do. Large sums are invested in processes for the removal of this element from ores before they come to the blast-furnace, and much greater sums in freeing the pig-iron from it. Mechanical engineers are becoming more and more critical of the amount of total phosphorus left in structural steel, the tendency being to require that it be reduced to the lowest possible figure. The old maximum of 0.1 per cent. is now considered much too high for first-class structural steel, and demands for 0.03 to 0.01 per cent. are by no means unheard of. The first to speak, in a scientific way, of the harmful effect of phosphorus on iron and steel appears to have been Meyer, who, in 1781, made mention of what we now term "cold-shortness," ascribing it to the presence of this metalloid, but not suggesting any remedy. It is, however, doubtful if a clear idea of this subject was possessed by the scientific world until after the invention of the pneumatic or Bessemer process, in 1855-56. One of the chief obstacles in the way of this renowned metallurgist,—one, indeed, the removal of which was the sine qua non of success,—was the phosphorus in the iron blown. The effect of the phosphorus does not seem to have been apprehended until many and costly experiments had been made, and then the required minimum percentage of it in the iron was secured only by the use of low-phosphorus ores. It was not until '1879-80 that practical success was reached, by the Thomas process, in the actual removal of the phosphorus from the iron. We now know something of the effect of the total amount of phosphorus on iron and steel, but very little as to the effect of the condition of the phosphorus. The state of combination in which

Jan 1, 1893

By Floyd C. Kelly

There is an ever-increasing demand for furnaces with controlled atmosphere, due to the large quantities of steel being used in the automotive industry, such as the high-chromium stainless irons, the 18 Cr, 8 Ni stainless iron and low-carbon steel sheets. The difficulties involved in the annealing of such materials, if they are to be kept absolutely free from oxidation, are many. It is possible to bright-anneal these steels in small laboratory hydrogen furnaces, using specially purified hydrogen and taking some additional precautions. In the first place, the insulation, usually of alumina or magnesia, holds small amounts of water vapor, which it is almost impossible to remove completely. Secondly, there is always condensataion of water vapor in the cooling chambers of such furnaces, and with the continuous circulation of the hydrogen gas in the furnace, the water vapor is carried from the cooling chamber back into the heating chamber. This water vapor oxidizes the charge. Lastly, the supply of moisture is made sure by the diffusion of small amounts of air from the atmosphere into the furnace against the pressure of the hydrogen. The oxygen combines with the hydrogen and forms more water. Under such conditions there is little gained by using specially purified gas, because it becomes contaminated after reaching the furnace. Low-carbon Steel If a sheet of low-carbon steel is annealed in such a furnace at 750" C. and allowed to cool with the furnace, an adequate flow of purified hydrogen being maintained all of the time, the steel will come out with a very thin coating of blue oxide. If a similar sheet is annealed at the same temperature and quickly pushed into the cooling chamber, it will come out nearly bright, or perhaps with only the edges slightly discolored. It is difficult to get a piece of steel through a furnace of this type with an absolutely bright surface. This is due to the fact that there are always traces of oxygen or water vapor in the furnace. When the steel is allowed to cool with the furnace, it reaches a critical temperature where the affinity of iron for oxygen is greater than that of hydrogen for oxygen, and the steel comes out discolored. If the steel is pushed from the hot zone

Jan 1, 1931

By V. Annamalai, J. B. Hiskey

The kinetics of copper cementation on a rotating disc of pure aluminum were studied as a function of chloride ion concentration, rotational speed of the aluminum disc, hydrogen ion concentration, copper ion concentration, and temperature. The optimum experimental conditions for all the parameters were determined. Chloride ion was found to destroy the naturally existing aluminum oxide film, and enabled the cementation reaction to proceed. A two-step rate, observed in most of the experiments, was attributed to the attainment of a roughened surface. An Evans diagram for the copper-pure aluminum system was constructed and utilized in predicting the controlling mechanism of the system. At low temperatures (<33°C), the rate with an experimental activation energy of 20.36 kcal mol- 1 was controlled by the presence of an oxide layer. While at higher temperatures presence of an oxide layer. While at higher temperatures (>33° mol- 1 was controlled by ionic diffusion. The deposits obtained were pure copper and not a copper-aluminum alloy. The amount of aluminum dissolved was determined for each experiment, and the maximum excess consumption was found to be only 40%. The structural characteristics of the copper deposits were studied using a scanning electron microscope. These observations indicated that the deposits were either bulbous, massive crystalline, or dendrites of different degrees of fineness depending on the experimental variables. The reaction rates seemed to depend on the deposit structures in a predictable way when a particular experimental parameter was varied.

Jan 1, 1979

By James Terry Duce

In order to facilitate interpretation of the data in this chapter, we print the following excerpts from circulars to authors, compiled by Mr. Frank A. Herald when he was Vice-chairman for Production of the Petroleum Division, and revised in 1939. Generally in Table 1 the unit for prescntation of data is a field. For our purposes a field is defined as the whole of a surface area wherein productive locations are continuous. Such unit commonly includes and surrounds nonproductive areas. Such unit commonly includes a great variety of geologic conditions—several units of continuous productive reservoirs of distinctly different structure and of distinctly different stratigraphy. Therefore it is hoped that our authors will subdivide "field" so as to enable students to make analyses that may have scientific and /or commercial value. As to each spacc in the tabulation, it is citller (1) not applicable, (2) the proper entry is not determinable, (3) the proper entry is determinable, but not determinable from data available to the author, (4) the proper entry is determinable by the author. In spaces not applicable, the author will please draw horizontal lines; in spaces where the proper entries are not determinable, the author will please insert x; in spaces where the proper entries are detcrminable but not detcrminable from data available to the author, the author will please insert y; in spaces where the proper entries are determinable by the author he will, of course, make such entries. Generally, y implies a hope that in some future year a definite figure will be available. Inability to determine precisely the correct entry for a particular space should not lead the author to insert merely y. Contributions of great value may be made by the author in many cases where entries arc not subject to precise determination. In such rases the author should use his good judgment and make the best entry possible under the circumstances. For many spaces, the correct entries represent the opinion of the author (for example, "Area Proved") and in such cases the entries need not be hedged to such extent as in cases where the quantities are definite yet can be ascertained only approximately by the author. In cases under definite headings but where figures are only approximate, the author may use x. For example, if the total production of a field is known to be between 1,800,000 and 1,850,000, the author may report 1,8xx,xxx; or if the production is between 1,850,000 and 1,900,000, the author may report 1,9xx,xxx. Where a numeral is immediately to the left of x or y, such numeral represents the nearest known number in that position. As to quantity of gas produced from many fields the question will arise as to whether the figures should include merely the gas marketed or should include also estimates of gas used in operations and gas wasted. Although rough approximations

Jan 1, 1939

The Western World&apos;s gold reserves now exceed 23,000 mt (750 million oz), 65% of which exist in South Africa. Although several major mines are reducing production or closing because of depletion of reserves, new mines or expansions of existing mines are coming on-stream which will maintain an annual production of 684 mt (22 million oz) of gold well into the 1990s. These new operations by the South African mining industry represent the largest expansion since the opening of the Witwatersrand gold fields in 1886. Included in three new mines being opened is that of Anglo American Corporation&apos;s Elandsrand plant, their fir& new gold venture in South Africa in seventeen years. Current average grade of South African mines is 8.2 g Au per mt (0.24 oz per st); and while the cost of the Elandsrand 135,000 mt (149,000 st) operation, including mine development, was about $314 million, it is estimated that the cost of a comparable operation started today and completed in the mid-1980s would be of the order of $480 million. New mines to exploit low-grade ore bodies are, therefore, likely to be few in number, and further expansion will undoubtedly be in the form of extensions to existkg operations where cash flow can be used to finance development. The authors&apos; first monograph, "Gold and Silver Cyanidation Plant Practice," devoted a section to South African cyanide plant operation; and it is believed that this new volume would not be complete without a description of Elandsrand, South Africa&apos;s newest gold plant. The Elandsrand mine is adjacent to Anglo American&apos;s Western Deep Levels on the Far West Rand. The decision to go ahead with the development was taken in mid-1974 from the results of exploration drilling carried out over a period of .lo years. Results of 17 bore holes and 68 intersections of the Ventersdorp Contact Reef had indicated a gold-.bearing reef less than one meter thick at a depth of 1,800 to 3,000 meters (5,900 to 9,840 ft). Preliminary studies indicated a mine of 900 km (560 miles) of underground workings would yield 725,000 kg (23. 3 million oz) of gold from 60 million mt (66 million st) of ore to be milled over a period of 34 years. Eventually, when the mine is in full production, the total hoisting capacity will be 300,000 mt per month (331,000 st) for a milling capacity of 225,000 mt per month (248,000 st). The Elandsrand surface facilities have been built on a low range of 0 hills to take maximum advantage of the 10 slope in transporting ore

Jan 1, 1981

By B. G. Zambre, G. A. Parks, J. N. Roco

Automatic controls have long been a fact of technological life. Some understanding of control systems is rapidly becoming essential to the competence of mineral engineers. Students in undergraduate mineral engineering curricula, however, should not be expected to develop proficiency in the design and interpretation of control systems. They should be provided the opportunity to absorb some of the fundamental concepts and cant of such highly specialized peripheral fields as automatic controls. The present paper describes the components of a simple, flexible and relatively inexpensive control system designed primarily for the use of students in independent study projects. The control system is based on a continuous on-stream optical analyzer analogous to commercially available systems using X-Ray fluorescence analysis. The components can be easily adapted to control other separators and separations. As described here, they have been arranged to control the magnetic separation of a magnetite bearing specular hematite from quartz to produce a quartz product of fixed hematite content using a minimum of power. The control system consists of the magnetic separator* with a vibrating feeder, † a sampler, an optical scanner, a differential amplifier, a millivolt recorder ‡ and a motor driven, metered variable DC power supply for the separator electromagnet. An optional magnet current recorder is useful. The system as arranged for closed loop control is illustrated in Fig. 1. The elements of the loop are identified in automatic control jargon in Table I. The same components can be easily adapted for use in other control modes.§.1 * A Carpco Induced Roll High Intensity Magnetic Separator (Carpco Manufacturing, Inc., Jacksonville, Fla.); modified for external magnet power supply. A Jeffrey-Traylor Vibrating Feeder Type 1B (Jeffrey Manufacturing Co., Columbus, 0.). A Beckman Laboratory Potentiometric Recorder (Beckman Instruments, Inc., 619-A) fitted with adjustable limit switches for external circuit control (Beckman Instruments, Inc.. 71980). Terminology is taken from ref. 1. CLOSED LOOP OPERATION The separation is monitored through the optical reflectivity of the tailings stream which is proportional to the hematite content, THA. The difference, A, between the measured analysis (actually a proportional voltage) and a reference analysis (also a proportional voltage) is continuously recorded. The separation is controlled through changes in the electromagnet current, I, supplied from a motor driven variable source. The two primary variables, ? and I, are linked through adjustable limit switches on the

Jan 1, 1965