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By H. Hubert

THE first attempts at direct utilization of blast-furnace gas in engines were made in 1895. For a considerable time the gas had been burnt in Cowper stoves for heating the blast for the furnace, and under the boilers which supplied steam to the blowing-engines, and others serving the furnaces. It was natural, therefore, that the idea of directly employing it in gas-engines should have occurred simultaneously to several engineers, notably to Lürmann and to Lencauchez, who had pointed out the blast-furnace as a powerful -gas-producer. Nevertheless, nowhere had any attempt been made to apply it to this purpose up to the end of 1894, when Thwaite proposed it to Mr. James Riley, of the Glasgow Iron & Steel Company. About the same time investigations were being made in Belgium and in Germany, independently of Thwaite's experiments, which were not generally known on the Continent. The industrial world, which up to that time had hardly favored the idea, had thus been gradually prepared to receive it. The gas-engine, long restricted to small sizes and dependent upon the use of an expensive fuel obtainable only in large centers, now began to make headway. At the Paris Exhibition of 1889 two engines of 100 h.p. were shown and excited much interest among engineers. One had four cylinders, and was made at the celebrated works of the Deutz Company, and the other was a single-cylinder engine, exhibited by two French designers, Messrs. Delamare-Deboutteville and Malandin. In the meanwhile the design of gas-producers had made important progress, completely freeing the new engine from its

Nov 1, 1906

By N. A. Zeigler, T. D. Yensen

Aging is a term that connotes a slow change in properties under ordinary operating conditions. It can be accelerated by increasing the temperature and by mechanical straining. The magnetic properties of iron and some of its alloys have for many years been known to be subject to such a change. But the cause of the change was not recognized until a few years ago after mechanical age-hardening in non-ferrous alloys of the "duralumin" type had been definitely shown, by means of solid solubility curves, changes in electrical resistance and microanalysis, to be caused by slow precipitation of one or more constituents from the solid solution. The similarity between the solid solubility curves of such alloys (Fig. 1) and those for iron-nitrogen (Fig. 2) and iron-carbon alloys (Fig. 3) below the A1 transformation point suggested at once that magnetic aging of iron might be caused by a similar process; namely, by the slow precipitation of carbon and nitrogen in the form of Fe4N and Fe3C at ordinary temperatures because of a cooling rate that had been too rapid to permit complete precipitation according to equilibrium conditions. This suggestion has since been amply confirmed, particularly by the comprehensive work of Köster1 on the effect of nitrogen and carbon. Typical curves are shown in Fig. 4 for the relationship between aging temperature and coercive force. Previous to the establishment of the precipitation-hardening theory it was thought that the effect of nonmetallic elements like C, N, O, etc., on the magnetic properties of iron was greatest when these elements were retained in solid solution, atomically dispersed throughout the interstitial spaces of the iron lattice2. Based on the theory that magnetic properties are intimately connected with the regularity of the lattice, it now follows quite logically that a greater effect on this regularity may be obtained when the above impurities are precipitated as very fine particles of Fe3C, Fe4N, FeO, etc., more or less uniformly dispersed within the grains. But if this is the case, it follows also that there must exist a relationship between the size

Jan 1, 1935

By N. A. Zeigler, T. D. Yensen

Aging is a term that connotes a slow change in properties under ordinary operating conditions. It can be accelerated by increasing the temperature and by mechanical straining. The magnetic properties of iron and some of its alloys have for many years been known to be subject to such a change. But the cause of the change was not recognized until a few years ago after mechanical age-hardening in non-ferrous alloys of the "duralumin" type had been definitely shown, by means of solid solubility curves, changes in electrical resistance and microanalysis, to be caused by slow precipitation of one or more constituents from the solid solution. The similarity between the solid solubility curves of such alloys (Fig. 1) and those for iron-nitrogen (Fig. 2) and iron-carbon alloys (Fig. 3) below the A1 transformation point suggested at once that magnetic aging of iron might be caused by a similar process; namely, by the slow precipitation of carbon and nitrogen in the form of Fe4N and Fe3C at ordinary temperatures because of a cooling rate that had been too rapid to permit complete precipitation according to equilibrium conditions. This suggestion has since been amply confirmed, particularly by the comprehensive work of Köster1 on the effect of nitrogen and carbon. Typical curves are shown in Fig. 4 for the relationship between aging temperature and coercive force. Previous to the establishment of the precipitation-hardening theory it was thought that the effect of nonmetallic elements like C, N, O, etc., on the magnetic properties of iron was greatest when these elements were retained in solid solution, atomically dispersed throughout the interstitial spaces of the iron lattice2. Based on the theory that magnetic properties are intimately connected with the regularity of the lattice, it now follows quite logically that a greater effect on this regularity may be obtained when the above impurities are precipitated as very fine particles of Fe3C, Fe4N, FeO, etc., more or less uniformly dispersed within the grains. But if this is the case, it follows also that there must exist a relationship between the size

Jan 1, 1935

By Charles R. Fettke

The permeability of an oil or gas sand is its capacity for transmitting fluids, either liquids or gases, under pressure. The permeability of a sand depends upon the size and shape of the openings in it and the extent to which these communicate with one another, as well as upon the ratio of their volume to the total volume of the sand. The apparatus employed and the method of procedure used by the authors in conducting the permeability tests have been described in a previous pub1ication.l For the tests described here 1/2-in. cubes were used. They were set in the lower end of a 1-in. union, inserted in a square hole cut in a hard rubber stopper which fitted into the lower end of the union. In the tests with air, volumes were measured with a wet American gas meter of 100 cu. ft. capacity. In those with water, distilled water at room temperature was employed, unless otherwise noted. DescRiption of Sands Tested The tests described in this paper were performed upon 18 samples representing typical oil and gas sands from 7 localities in northwestern Pennsylvania. For purposes of identification, the cores from which the samples came have been designated by capital letters, the sequence of the samples in the cores by numerals, and the individual cubes by small letters. All cubes from the same samples came from adjacent portions parallel to the bedding. Core A of the Bradford sand came from the north central part of the Bradford field, from an area where water-flooding operations have proved highly successful. Core B of the same sand was obtained from the southern part of the field. This core contained a so-called "loose streak," 7.5 ft. thick, in the middle portion of which B2 is a representative sample. The "loose streak" has given trouble in water-flooding but responded favorably to an air-drive, using a pressure of 300 lb. The natural production was increased approximately five times over a period of three years in which the air-drive was in operation. Core C, also of the Brad-

Jan 1, 1931

By N. G. W., Cook

When an excavation is made underground the original rock stresses are removed from the surfaces of the excavation. These surfaces converge to partially close the excavation and the superincumbent rock mass moves down towards the excavation. If the convergence of the surfaces of the excavation were controlled, energy generated by their motion against the controlling forces could be extracted. Since the total forces in the rock mass are not significantly affected by the excavation, stress concentrations arise around the excavation, which compensate exactly for those stresses no longer transmitted through the excavation. These phenomena give rise to two general principles which provide the basis for analyzing the effects of making any underground excavation. The first of these is that the total force resulting from the stresses across any plane in the rock, including any plane through the excavation, must be the same before and after the excavation is made. The second of these is that energy must necessarily be released as a result of making an underground excavation.

Jan 1, 1969

By A. J. Griest, P. D. Frost, H. A. Robinson

The flow characteristics and uniform elongation of alpha-beta titanium alloys in the solution-treated condition were shown to be markedly affected by the solution temperature. Two classes of alpha-beta alloys were distinguished, based on the effect of solution temperature on the uniform elongation. Martensitic alpha-beta alloys, which are relatively weakly beta-stabilized, showed decreasing values of uniform elongation as the solution temperature was initially increased. However, after solution-treatment at still higher temperatures in the alpha-beta field, the uniform elongation of these alloys was again high, and often attained its maximum value. Nonmartensitic alpha-beta alloys, which are more heavily beta-stabilized, showed a continuous decrease of uniform elongation with increasing solution temperature. The behavior was rationalized in terms of the alpha-beta ratio and the alloy content of the beta existing at the solution temperature. The data indicate that in commercial practice close temperature control may be required to get maximum uniform elongotion, and hence, maximum potential formability, in solution-treated sheet. Bend-test data also were obtained for the solution-treated conditions. A MOST important objective of current titanium research is the development of age-hardenable alloys with superior formability in the solution -treated condition. Alpha-beta titanium alloys have been shown to be amenable to high-strength aging treatments after solution-treatment in the alpha-beta field.' However, heat-treatment data on the properties of solution-treated sheet, such as uniform elongation, minimum bend radius, and flow properties, which have a bearing on the potential formability, have not been widely available. This paper presents only the most significant results of a research program conducted at Battelle for the Air Force in an effort to develop sheet alloys that can be formed readily as solution-treated and subsequently aged to very high strengths. Data for 10 compositions representative of the more than 25 alloys studied in this program are presented. A primary objective of the paper is to demonstrate the pronounced dependence of the flow characteristics and uniform elongation on solution-treatment temperature. This effect is believed to be vitally important in the commercial heat-treatment of age-hardenable titanium sheet alloys. Experimental Procedures Melting and Fabrication—The nominal and actual compositions, beta transi temperatures, and rolling temperatures of 10 of the 30 alloys studied are presented in Table I. Stock :€or two of the alloys, E (Ti- 8Mn) and J (Ti-6A1-4V) was obtained from commercial heats. The remaining heats, except D and I, were double melted as 10-lb heats in a consumable-electrode furnace. Melting stock was 120 Brine11 hardness sponge. The oxygen and hydrogen analyses spotted throughout the heats indicate the range of interstitial levels resulting from the melting practice used. Heats D and I were melted as 20-lb ingots with the same grade of sponge. These ingots were cut in half and one portion used in the present evaluation. The ingots, which were about 4 in. diam and 4 in. in height, were upset forged and drawn at 1750°F to sheet bar 5/8 in. thick by 2 1/2 in. wide in such a manner that the top of the ingot corresponded to the top of the sheet bar. Slabs of the sheet bar, 5 1/2 in. in length were scalped to 1/2 in. thickness and rolled at the temperatures indicated in Table I to approximately 0.055 in. sheet. Elongation during rolling took place at 90" to the original forged length. The fabrication procedure used is described in some detail since the experimental heats showed considerable directionality in mechanical properties. The rolling procedures for the commercial heats were unknown, but were such as to produce essentially isotropic properties. All heats, as rolled, showed microstructures typical of alpha-beta alloys worked in the alpha-beta field; that is, the structures consisted of equiaxed alpha particles in a beta matrix. Heat Treatment— The effects of solution and aging heat-treatments on the properties of the alloys were evaluated uSing longitudinal and transverse tensile and bend coupons sheared from the sheet. Two or three solution-treated conditions were evaluated for each alloy. In addition, the alloys were also tested after annealing at 1200°F for 4 hr and furnace cooling. The solution-treated and annealed conditions were those in which the alloys might be expected to

Jan 1, 1959

By A. CHESTER BEATTY

MAGNESIUM oxide is by far the most refractory of the common oxides, since it has a melting point of 5072 deg. F. as compared with 3110 deg. F., the melting point of silica (crystobalite) ; 3722 deg. F., the melting point of alumina (corundum) ; and 4127 deg. F., the melting point of chromite (Cr2O33FeO). Its large-scale use in the lining of metallurgical furnaces dates back to the latter part of the nineteenth century, when extensive deposits of magnesium carbonate were discovered in southern Austria in the province of Styria. Before the development of Austrian magnesite, calcined dolomite, a mixture of lime and magnesia, was used in basic steel-making furnaces. The lime in the dolomite was quite objectionable, since it slaked on exposure to the atmosphere, and dolomite therefore could not be made' .into permanent furnace bottoms or into brick. The Austrian magnesite, with its very low lime content, was free from these objections and soon displaced much of the dolomite. With the extensive development of basic steel-melting, the rise of the copper industry, and other metallurgical and chemical processes which dealt with chemically basic substances, the use of magnesite grain and magnesite brick increased rapidly.

Jan 1, 1931

By AIME AIME

LEADING off the Thursday morning session on Non-metallics was C. E. Heinrichs' paper, "Phosphate Flotation, Its Place in the Technology and Economics of the Phosphate Industry." Mr. Heinrichs also presented a closely related paper, "Milling Methods and Costs at the No. 2 Concentrator of the Phosphate Recovery Corporation," by H. S. Martin. The first of the papers points out the great significance of flotation to the phosphate industry, inasmuch as flotation practically doubles the potential recovery, thereby decreasing production costs and increasing reserves materially. The second paper describes three such plants, two of which are in Florida, the third being at Wales, Tenn. Operating characteristics and costs are reviewed. Answering inquiries from the floor, Mr. Heinrichs said that the adoption of a new parallel-shell dryer, from 60 to 80 ft. long, instead of the old single-shell countercurrent dryer, had increased the unit drying capacity over 300 per cent and had reduced the drying cost to less than 25c. per long ton of dried product. The initial moisture is from 15 to 18 per cent and the final about 2 per cent.

Jan 1, 1933

By Charles R. Wilson, Thomas W. Doe, Jane C. S Long, Howard K. Endo

An approach to treating flow through fractured rocks is presented which involves (1) determining statistical distributions for fracture area, density, orientation, and aperture from field data, (2) computer generation of fracture systems from the statistical distributions, and (3) analysis of the permeability and porosity of the fracture systems. The fracture density and orientation data my come from core logging or mapping. The hydraulically appropriate apertures and areas of the fractures come from transient flow analyses of single fracture well tests. These tests my also yield information on fracture deformability. Analysis of flow through computer generated fracture systems shows that an equivalent porous medium permeability can be defined for some fracture systems if a large number of fractures is taken into account.

Jan 1, 1982

By C. W. Phillips, R. S. Busk

With most cast metals the grain size may vary within wide limits, depending upon the conditions at the moment of freezing. These conditions are subject to control in magnesium-base alloys, by proper melting and superheating techniques, enabling production of quite uniform and fine-grained castings, almost independent of section thickness. However, such variations of grain size as do exist, in common with all metals, are reflected in corresponding changes in mechanical properties. It is the intent of this paper to present data giving the relationship between grain size and mechanical properties. Data are also included on the combined effects of grain size and micro-porosity. In addition, a short discussion of factors influencing the grain size of sand castings is included. Measurement OF Grain Size By grain size is meant the statistical distribution of volumes occupied by the individual crystallites in a metal section. Since this is almost always impossible of direct measurement, several methods of estimating and expressing the size have been evolved. Most exact methods make use of the microscope. This involves study of a single plane cut at random through the metal. What is seen in the microscopc are polygons, each the cross section of a grain. The diameters or areas of these polygons are then measured and the grain size is expressed as an average diameter, number of grains per unit area, average area per grain, or, rarely, average volume per grain. Rutherford, Abom, and Bain3 have discussed extensively the errors involved when using a plane section to estimate volume. They clearly point out that the tendency is to underestimate the true grain size because of the nature of the measurcment. The A.S.T.M. recommends that measurement be made by comparison with a standard chart, by means of Jeffries' planimetric method4 or Heyn's intercept method. The Society recommends that the notation be in terms of the number of grains per unit area (as is the grain-size number used for steel) or as an average diameter, expressed in inches or millimeters (as for copper and brass). The method of measurement used for this study was comparison with a standard chart, which has been described by P. F. George.5 The chart was constructed by photographing at Ioo diameters a uniform specimen with an average grain diameter of 0.003 in. The average diameter of this specimen was determined by numerous measurements, using both the Jeffries and Heyn methods. The other grain sizes were then obtained by appropriate enlargemcnt of the master sample. Careful comparison of the chart method with other methods on identical samples indicates that though the differences be-

Jan 1, 1945

By John L. Boardman, C. W. Goodale

The motives behind the organization of the Bureau of Safety were twofold. First, there was the policy of the company toward its employees, which was one of fairness and consideration for their welfare and which entails the prevention of injuries; second, in order to prevent injuries, a study of their causes was essential, and this study could be made only by a thorough systematic classification of accidents, which required a special department to form and carry out the plans. The Bureau of Safety was organized to begin operation Jan. 1, 1914, hut practically all of the first year was spent in collecting data, making plans, etc. This department is semi-independent of others and reports directly to the president and general manager. It consists of the president of the company and the managers of the following departments: Mines, Washoe Reduction Works, Great Falls Reduction Works, Coal department, lumber department, B. A. & P. railway; and the chairman of the Bureau of Safety. Working under this group is the General Safety Committee consisting of the manager of mines, as chairman, the general superintendent, two assistant general superintendents, and the heads of the following departments: mechanical, geological, purchasing, sampling works, and framing plant; and also the safety engineer. Operating under the General Safety Committee are the group safety committees, consisting of the Anaconda group of mines, Boston & Montana group of mines, zinc group of mines, Washoe reduction works at Anaconda, B. & M. reduction works at Great Falls, coal department, lumber department and the R. A. & P. railway. Each of these group safety committces was in charge of the superintendent or manager of the group represented and the committee consisted of the foremen of the mine's or works that the committee served, as well as the safety engineer. These foremen and superintendents had met regularly for the purpose

Jan 1, 1923

By John L. Boardman, C. W. Goodale

The motives behind the organization of the Bureau of Safety were twofold. First, there was the policy of the company toward its employees, which was one of fairness and consideration for their welfare and which entails the prevention of injuries; second, in order to prevent injuries, a study of their causes was essential, and this study could be made only by a thorough systematic classification of accidents, which required a special department to form and carry out the plans. The Bureau of Safety was organized to begin operation Jan. 1, 1914, hut practically all of the first year was spent in collecting data, making plans, etc. This department is semi-independent of others and reports directly to the president and general manager. It consists of the president of the company and the managers of the following departments: Mines, Washoe Reduction Works, Great Falls Reduction Works, Coal department, lumber department, B. A. & P. railway; and the chairman of the Bureau of Safety. Working under this group is the General Safety Committee consisting of the manager of mines, as chairman, the general superintendent, two assistant general superintendents, and the heads of the following departments: mechanical, geological, purchasing, sampling works, and framing plant; and also the safety engineer. Operating under the General Safety Committee are the group safety committees, consisting of the Anaconda group of mines, Boston & Montana group of mines, zinc group of mines, Washoe reduction works at Anaconda, B. & M. reduction works at Great Falls, coal department, lumber department and the R. A. & P. railway. Each of these group safety committces was in charge of the superintendent or manager of the group represented and the committee consisted of the foremen of the mine's or works that the committee served, as well as the safety engineer. These foremen and superintendents had met regularly for the purpose

Jan 1, 1923

By W. J. Rogers, L. J. Dwiggins, R. O. Williams

THERE has been comparatively little work on the importance of strain rate and temperature as variables in the formation of deformation textures. For this reason the present work was started, the choice of compression being in part that of convenience and in part because of the absence of quantitative data in this area. These do not turn out to be important variables within the range studied which permits the results to be condensed into this note. Samples 1/4 in. in diam and 1/2 in. long were machined from 99.9 pct pure commercial aluminum and recrystallized to a fine grain size. A set of five samples were deformed between a spring-driven weight and an anvil resulting in roughly 20 pct strain each time. The strain rate varied because of decle-ration and shortening of the sample but would average about 10&apos; per min. Deformation at temperatures over the range of -76" to 150°C were obtained by heating or cooling the samples. Complete lubrication could be obtained by oil since the short time of contact did not permit its escape. The samples were compressed to a total true strain of 1.4 to 1.6. A larger sample was prepared similarly with spiral grooves in the ends to hold paraffin which provided essentially complete lubrication. This sam ple was compressed slowly at room temperature at a rate of about 2 per min to a total strain of 1.0. Cylindrical samples were carefully machined from these discs with a radial direction as an axis. They came from the center half of the samples and were roughly 1/16 in. in diam. The samples were etched down 15 pct to remove any surface effects. Diffraction data were then obtained for six different kinds of planes by the use of the Norton technique as applied to a fiber texture. Direct comparison between the raw data failed to reveal any significant difference between any of the samples and consequently the data from only one sample was completely reduced. The particular sample had been deformed at O°C The background was subtracted from the intensity data which were averaged over the four quadrants and then normalized to random. These data were then used to obtain fiber-axis distribution charts as previously described.2 For this sample the (422) plane was also run to assist in this inversion. The final result, Fig. 1, provided a comparable fit to that previously obtained from fiber data. About 85 pct of the material forms an elliptical texture around the <110> direction. The radius (at half height) is 5.5 deg along the (111) boundary and 8 deg along the (100) boundary. The remaining 15 pct forms a ridge running from this texture to near the <311> direction. The regions around the (100) and (111) planes are devoid of material. The earlier qualitative results of ~arrett~ are in complete agreement with the present results. The possibility has been dis-cused that the material around the <311> results from friction between the sample and compression plates.4 The present results are considered proof that such is not the case because of the uniformity of sample deformation and the requirement of axial symmetry before fiber-axis distribution charts can be accurately obtained. Recently results have been obtained to show that strain rate and temperature are important variables in the extrusion of aluminum.5 Perhaps the most important observation was that the partial recrystal-lization occurred even at room temperature. Strain rate was considered to be a factor only in that it produced a temperature change. There are many differences between the two experiments, the most important possibly being that their material was roughly ten times the purity of the present material. The present experiment, however, may not be as definitive as desired in this respect since it has been shown that compressed aluminum recrystallizes without a texture change6 although supplementary

Jan 1, 1961

By John Eash

DURING recent years nickel has had an increasingly important role as an alloying element in the copper-tin bronzes. Nickel additions not only produce better casting alloys but also make alloys whose properties can be varied by precipitation hardening; thus leading to increased commercial application of copper-nickel-tin alloys. Recent investigations have indicated a decrease in the solubility of tin in the alpha phase as the annealing temperature is lowered and as the nickel content is increased within certain limits. A further change caused by the nickel additions is produced in the excess phase of the copper-tin bronzes. The alpha plus delta eutectoid is replaced by a clear precipitated constituent in the alloys containing up to 15 per cent tin and not less than 1 per cent nickel. This paper has a dual purpose. The first is to present a new determination of the alpha-phase boundary in alloys containing from 0 to 20 per cent nickel, together with the liquidus and solidus temperatures above that field. The second purpose is to give the equilibrium conditions existing in alloys exceeding the alpha phase containing up to 31 per cent tin and 5 per cent nickel, so that the disappearance of the alpha plus delta eutectoid constituent may be explained. After considering the earlier investigations of the related alloy systems and the experimental procedure used in this investigation, the alloys will be discussed in groups as separate quasibinary systems containing constant amounts of nickel. The systems considered contain 0, 1, 2, 3, 5, 10 and 20 per cent nickel. The straight copper-tin system was reinvestigated in order to establish a foundation on which to build the remaining material. The 1 per cent nickel alloys studied give the relations existing in the region of the eutectoid transformation between the copper-tin system and the 2 per cent nickel copper-tin system which has been investigated in detail. The thorough examination of the latter system was made since 2 per cent of nickel is representative of the commercial additions to the cast bronzes and also because it is sufficient to produce

Jan 1, 1932

By John T. Eash, Clair Upthegrove

During recent years nickel has had an increasingly important role as an alloying element in the copper-tin bronzes. Nickel additions not only produce better casting alloys but also make alloys whose properties can be varied by precipitation hardening; thus leading to increased commercial application of copper-nickel-tin alloys. Recent investigations have indicated a decrease in the solubility of tin in the alpha phase as the annealing temperature is lowered and as the nickel content is increased within certain limits. A further change caused by the nickel additions is produced in the excess phase of the copper-tin bronzes. The alpha plus delta eutectoid is replaced by a clear precipitated constituent in the alloys containing up to 15 per cent tin and not less than 1 per cent nickel. This paper has a dual purpose. The first is to present a new determination of the alpha-phase boundary in alloys containing from 0 to 20 per cent nickel, together with the liquidus and solidus temperatures above that field. The second purpose is to give the equilibrium conditions existing in alloys exceeding the alpha phase containing up to 31 per cent tin and 5 per cent nickel, so that the disappearance of the alpha plus delta eutectoid constituent may be explained. After considering the earlier investigations of the related alloy systems and the experimental procedure used in this investigation, the alloys will be discussed in groups as separate quasibinary systems containing constant amounts of nickel. The systems considered contain 0, 1, 2, 3, 5, 10 and 20 per cent nickel. The straight copper-tin system was reinvesti-gated in order to establish a foundation on which to build the remaining material. The 1 per cent nickel alloys studied give the relations existing in the region of the eutectoid transformation between the copper-tin system and the 2 per cent nickel copper-tin system which has been investigated in detail. The thorough examination of the latter system was made since 2 per cent of nickel is representative of the commercial additions to the cast bronzes and also because it is sufficient to produce

Jan 1, 1933

By David G. Chedgy, Wen L. Chen, Bill S. Taylor

Theoretically the heavy medium cyclone is capable of cleaning raw coal from a top size of about 38 mm (1 1/2 in.) to a bottom size of about 200 mesh. With this idea, plants have been built recently using the heavy medium cyclone without desliming. The full size range down to zero is fed into the cyclone. Products + 28 mesh are removed in the normal manner on drain and rinse screens. The 28 x 200 mesh products are recovered separately from the magnetic separator tailings. Simplicity of flowsheet and plant operation coupled with the high efficiency of the heavy medium cyclone makes this a very attractive approach.

Jan 1, 1980

By Evan Just

Attempting to analyze a 25-year forecast after less than a third of the time has elapsed may seem premature. The President&apos;s Materials Policy Com- mission&apos;s report necessarily painted with a broad brush and made no claim for pinpoint accuracy in its predictions. More importantly for present purposes, it made no attempt to predict the detailed courses of production and consumption during the period forecasted. Several statistical highs and lows may very well lie between now and 1957, so comparing recent figures with points taken from the report on a straight-line basis would be illogical. Moreover, the report assumed that the general trend of consumption-domestic and foreign-would be upward. Contrarily, domestic figures were lower in 1957 than in 1950. Therefore, to project curves from 1950 through 1957 leads to conclusions that are probably false. Many in the industry would feel more uncertain about forecasting 1975 domestic conditions now than they would have been in 1950, even though nearly a third of the 25 years has elapsed. In making comparisons, several statistical problems are encountered. The Paley report figures for 1950 were estimated in several cases and corrected figures vary as much as 10 pct. For example, the report placed 1950 lead consumption at 800,000 tons, whereas actual consumption was 885,000 tons. Obviously, in comparing more recent figures with the report&apos;s projections, adjustments must be made for positions taken in error from the start. Over the long pull, such discrepancies will probably be insignificant, but they must be noted in comparing short-term changes.

Jan 10, 1959

By AIME AIME

THE 131st meeting of the American Institute of Mining and Metallurgical Engineers was held in New York on Feb. 16 to 20, 1925, with the largest registration of any previous meeting, the total being 1320 compared to 1276 in 1924. The technical sessions were more largely attended and aroused more discussion than ever before. There were joint meetings with the Mining Section of the National Safety Council, under the auspices of the Industrial Relations Committee of the Institute and two very important lectures, the Howe Memorial Lecture, under the auspices of the Iron and Steel Committee, and the lecture by Dr. Carl Benedicks, of Sweden, on Corrosion, under the auspices of the Institute of Metals Division. The Petroleum Division conducted its annual Symposium on Oil which will be published later in book form. At the annual business meeting on Feb. 17, the following ticket was elected, and the reports of the President, Treasurer, and Secretary &apos;were presented:

Jan 1, 1925

By S. R. Elliott

The Spies mine is located in the eastern half of the northwest quarter of section 2443-35, near the village of Iron River, Mich., and is operated by The Cleveland-Cliffs Iron Co. Speaking generally, the jasper hanging walls of most of the deposits in the Iron River district dip at a steep angle and are exceedingly strong, standing without caving, even after mining has been continued for years and after large excavations have been made. The ore is fairly hard and tough and contains no slippage faces. It occurs in large masses, which are often egg shape, with the smaller end down, and can be mined in open stopes without the use of timber. The common system employed in the district is the shrinkage stope, or some modification of it. The Spies system was developed to utilize the advantages of the open-stope method and to avoid the disadvantages of the shrinkage stope. The Spies shaft was sunk to such a depth that the bottom, or third level, was in rock at a short distance below the bottom of the orebody, the shape and extent of which had been previously determined by diamond drilling. This is shown in plan and by the ore contours at the first, second, and third levels in Fig. 1, and in section in Figs. 2 to 7. In order to provide the necessary mills and raises, three parallel crosscuts were driven on 25 ft. centers on the bottom level. Drifts on the second and first levels were driven to the orebody and followed the foot wall in a southerly direction to the end of the ore. In crosscut 3, Fig. 1, raises 30, 40, 50, and 60 were carried up on the foot wall and holed into the second level, and were ultimately carried up and holed into the first level. These foot-wall raises carry the pipes and ladders, provide a means of ventilation, and furnish safe communication to all working places in the stope. From crosscuts 1, 2, and 3, raises were completed to a height of 32 ft., or the elevation of the first sublevel. They were then connected by east and west crosscuts to the main foot-wall raises 30, 40, 50, and 60, shown in Fig. 4. The crosscuts in raises 1 to 5 were then driven west and the

Jan 1, 1923

By S. R. Elliott

The Spies mine is located in the eastern half of the northwest quarter of section 2443-35, near the village of Iron River, Mich., and is operated by The Cleveland-Cliffs Iron Co. Speaking generally, the jasper hanging walls of most of the deposits in the Iron River district dip at a steep angle and are exceedingly strong, standing without caving, even after mining has been continued for years and after large excavations have been made. The ore is fairly hard and tough and contains no slippage faces. It occurs in large masses, which are often egg shape, with the smaller end down, and can be mined in open stopes without the use of timber. The common system employed in the district is the shrinkage stope, or some modification of it. The Spies system was developed to utilize the advantages of the open-stope method and to avoid the disadvantages of the shrinkage stope. The Spies shaft was sunk to such a depth that the bottom, or third level, was in rock at a short distance below the bottom of the orebody, the shape and extent of which had been previously determined by diamond drilling. This is shown in plan and by the ore contours at the first, second, and third levels in Fig. 1, and in section in Figs. 2 to 7. In order to provide the necessary mills and raises, three parallel crosscuts were driven on 25 ft. centers on the bottom level. Drifts on the second and first levels were driven to the orebody and followed the foot wall in a southerly direction to the end of the ore. In crosscut 3, Fig. 1, raises 30, 40, 50, and 60 were carried up on the foot wall and holed into the second level, and were ultimately carried up and holed into the first level. These foot-wall raises carry the pipes and ladders, provide a means of ventilation, and furnish safe communication to all working places in the stope. From crosscuts 1, 2, and 3, raises were completed to a height of 32 ft., or the elevation of the first sublevel. They were then connected by east and west crosscuts to the main foot-wall raises 30, 40, 50, and 60, shown in Fig. 4. The crosscuts in raises 1 to 5 were then driven west and the

Jan 1, 1923