Search Documents

By J. A. Herbst, K. Rajamani, Y. C. Lo

In spite of potential theoretical and economic advantages of large-diameter ball mills, many manufacturers elect not to build them owing to what is perceived as an excessively large design risk. This is because traditional predictions for mill scaleup to large diameters are not always accurate. Alternative methods of analysis and scale-up are required. Recent studies have shown that detailed population balance models which account for important grinding subprocesses (grinding kinetics, material transport, and classification) are capable of predicting the performance of small- and intermediate-diameter mills (up to 4.3 m, or 14 ft) from small-scale batch tests. These same models are used in the current study to predict the performance of a "borderline "large ball mill (4.7 x 5.5 m, or 15 x 18 ft) at Asarco's Sacaton operation, a ball mill (5 x 5.8 m, or 16.4 x 19 ft) at Kennecott's Chino operation, and one of the world's largest ball mills (5.5 x 6.4 m, or 18 x 21 ft) at Cities Service Pinto Valley operation. Model parameters required for scale-up have been estimated in a 380-mm-diam (15-in.-diam) batch mill. Predictions are compared with the results of detailed plant sampling in the three plants. For the Sacaton and Chino operations, the error of the predictions was found to be less than 2.5%, while the corresponding error for the Pinto Valley operation was less than 2.7%. It is concluded that proper representation of the major subprocesses of grinding in the model equations is the key to achieving accurate scale-up. Of special importance is the need to account for the size distribution of the grinding media and the influence of the size distribution environment in the mill on grinding kinetics.

Jan 1, 1986

[NOTE.-The names of authors of papers are printed in small capitals, and the titles of papers, in italics. Casual notices, giving but little information, are indicated by bracketed page numbers. Large Roman numerals are volume numbers; small Roman numerals after volume numbers following titles indicate the page on which the presentation of the paper is mentioned; Arabic figures refer to the text of the printed papers.] A Use Classification of Coal, (ASHLEY) LXII [xiv]; LXIII, 782; Discussion: (HALL), 794; (ZERN) , 795; (ASHLEY), 795 Absorbent material, liquid-oxygen explosives, LXXI, 1251. Absorbents for liquid-oxygen explosives, LXIX, 292, 299. Absorption : cupellation : gold, special cupels, LIX, 194. primary and secondary, LIX, 213. ratio of silver to gold, LIX, 212. silver, specla1 cupels, LIX, 195. Absorption method, gasoline from natural gas, LIX, 584, 585. Absorptzon of Sulfur from Producer Gas zn Open-hearth Furnaces (NEAD), LXX, 176; Discussion: ( WATERHOUSE), 184 ; (REYNDERS) , 184; (KINNEY), 184 Accelerated wearing tests, bearing metals, LXIX, 973. Accident prevention, results, Utah, LXVIII, 360 Accident Prevention, 1919 (SINN), LXIII, [xiii] Accidents: causes in coal mines, LXXI, 1229. classification, Anaconda Copper Mining Co., LXVIII, 9. coal mining: comparison with metal mining, LXVIII, 360. pillar mining, LXVIII, 323. relation to method, LXVIII, 323 shafts, LXVIII, 207, 209 Utah, LXVIII, 363 - concentrating mills, Utah, LXVIII, 362 liquid-oxygen explosives, LXIX, 330, 339 losses through, LVIII, 65 metal mining, LXVIII, 361, 363. mine: causes, LIX, 652. curve of decrease, LIX, 655 days of greatest frequency, LIX, 657 human element as cause, LIX, 652, 653. intemperance as cause, LIX, 658 labor relation, LIX, 652 prevention, LIX, 653. record, New Jersey Zinc Co., Franklin mine, LIX, 655 time of greatest frequency, LIX, 657, 658 Utah, LXVIII, 360 prevention, LVIII, 65 report blanks, Anaconda Copper Mining Co, LXVIII, 13, 15. statistical base, Anaconda Copper Mining Co, LXVIII, 9 time lost, LVIII, 70 transportation, Clifton-Morenci district, LXX, 851.

Jan 1, 1926

By N. M. Raju, B. Singh

The paper seeks to present the results of experimentation in room and pillar stopes with different ground conditions to determine the safe working span. In the experimental stopes, ground movement was monitored with gradual widening of the room span. The field measurements included closure between the stope walls and the extent of ground movement in the hangwall using borehole extensometers. hock bolting was used as an exclusive support system which enabled introduction of scrapers for improving productivity. In one nine, phosphate bed, 3 to 3.5 m thick dipping at 45O and overlaid by weak laminated shale, was worked at shallow depth of cover. h the experimental panel, five s topes were worked with spans varying from 5.5 to 7 m. In the second mine, the chalcopyrite orebody up to 6 m in thickness dipping at 25 - 30" was worked at a depth of 1100 m. The hangwall consisted of fairly competent schistose rocks and therefore 10 to 15 m wide spans could be experimented. The field measurements confirmed that in the phosphate mine with weak shale roof, 7 m span could be safely worked with subsequent caving of the bolted roof. In the copper mine, 15 m span could be worked and the stopes required subsequent backfilling for better ground control.

Jan 1, 1983

SOUTHERN CALIFORNIA SECTION Executive Committee SEELEY W. MUDD, Chairman. C. COLCOCK JONES, Vice-Chairman. FREDERICK J. H. MERRILL, Secretary-Treasurer, 631 Higgins. Bldg., Los Angeles, Cal. RALPH ARNOLD A. B. CARPENTER A. B. W. HODGES WILLIAM F. STAUNTON The third meeting of this winter season tool: place in a private dining room of the Sierra Madre Club in Los Angeles on Feb. 1, 1916, at 6:30 p.m., 22 members and guests being present. In the absence of the Chairman, S. W. Mudd, the Vice-Chairman, C. Colcock Jones, presided. After an enjoyable dinner the meeting was called to order, and the first paper by Ralph Arnold on Conservation of Oil and Gas in the Americas was read by the Secretary. W. F. Staunton then read an important paper on The Influence of California Oil on the Mining Industry of the West. In this he touched upon the uses of oil as a fuel for generating power, especially in connection with the Diesel engine. This paper was discussed it some length by J. F. Mitchell-Roberts, R. B. Moran, F. H. Asbury and L. D. Godshall. The Chair then introduced Robert B. Moran of the California State Mining Bureau, Deputy Supervisor of Gas and Oil, for the' Los Angeles . District, who addressed the meeting on the work of his department. The meeting concluded with A. B. Carpenter's reading of a paper on The California Gasoline Industry by W. R.. Hamilton, Manager of the Ventura Refining Co. F. J. H. MERRILL, Secretary. ,

Jan 4, 1916

By E. T. Turkdogan, P. Grieveson

It is shown experimentally that, by making use of the coupled S-O reaction in ionic melts, it is possible to transfer slclJur or oxygen from a lozv to a high chemical potential through an ionic nzenzbrane. This uphill transfer of sulfur is accompanied by a counter downhill transfer of oxygen and vice versa. The Materials balance shows that the amoulits of sul -fur and oxygen lost or gained by one system are the same as those gained or lost by the other systenz — the two systejns being separated by an iofzic membmne. The systems used in these experi?nents were solid Mn-MnS-Mno and liquid Fe-S-0. Sufficient results were obtained Lo study the kinetics of the transfer and the indications are that the counter diffusion of sulfide and oxide iojzs in the membrane is the rate controlling process. WHEN an ionic oxide-melt reacts with an atmosphere containing sulfur and oxygen-bear ing gases the following reaction occurs: 1/2 S2 (gas) +O2- (melt) = S2- (melt) + 1/2 0, (gas) [1] Under the restrictions that i) electric conductance in the melt is purely ionic and ii) each constituent element in the melt does not change valence, the solution of an atom of sulfur in the melt will result in the evolution of an atom of oxygen, so that the electric neutrality is maintained. For a given temperature and melt composition, the equilibrium concentration of sulfur in the melt is determined by the ratio, po2 /ps2 , in the gas phase and not by the individual partial pressures of oxygen and sulfur. This has been demonstrated by a number of investigators, for example by Richardson and withers', Fincham and Richardson,la by St Pierre and Chipman,' and by Turkdogan and Darken.3 In his Howe Memorial Lecture for 1961, Darken discussed the possibility of uphill pumping of sulfur through an ionic membrane at the expense of oxygen. TO test the validity of this concept associated with coupled reactions, experiments were carried out in the following manner. A presintered mixture of Mn-MnS-MnO and prefused mixture of Fe-S-0, contained in platinum and iridium crucibles, respectively, and separated by a thin layer of soda-glass (to act as an ionic membrane), were placed side by side in an evacuated silica capsule and sealed. This was then kept at 1400°K for a required time to allow Reaction [11 to occur via the ionic membrane. When partial equilibrium is reached, the ratios Po2 /pS2, for systems on either side of the membrane, are equal and the flux of sulfur and oxygen through the membrane becomes zero, although the individual partial pressures po2 andp,, in these two systems may differ considerably.

Jan 1, 1962

By H. A. Doerner, F. D. DeVaney, J.B. Clemmer

Production of magnesium metal in the United States during the past decade has increased from less than 600,000 lb. in 1928 to more than 4,800,000 lb. in 1938.1 The growing industry has stimulated interest in methods of production and in sources of raw material. All of the present domestic production is from brines. However, the availability of large tonnages of magnesite in the state of Washington, together with the possibility of cheap power, have created interest in the utilization of magnesite for the production of magnesium metal as well as for other purposes. Magnesite, the carbonate of magnesium (MgCO3), usually is associated with limestone (CaC03) and dolomite (MgCO3. CaC03). It occurs in crystalline and microcrystalline (sometimes termed amorphous) forms.2 The more common crystalline mineral is found in various shades of white, gray, yellow and brown, the colors being due to impurities, chiefly iron. Magnesite has a hardness of 3.5 to 4.5 and a specific gravity of 3.0 to 3.1. It forms rhombohedra1 crystals in the hexagonal system, having a vitreous, pearly luster. The quarries and mines of the Northwest Magnesite Co. near Chewelah, Wash., are large producers of magnesite for refractories. The deposits are extensive, some veins being hundreds of feet wide. The boundaries of the veins are indefinite, and the magnesite is interfingered with dolomite. Calcite, talc, serpentine, quartz and shale are disseminated through the deposits. The quality of the ore cannot be determined by appearance or by simple tests; chemical analysis is required. These features make it difficult to determine the boundaries or total quantity of workable ore.3 Only the higher-grade ores are mined, and a considerable proportion of the magnesite content is discarded by hand-sorting and log-washing methods. After calcining, the sorted product meets the specifications for usual refractory material, as it contains approximately 81 per cent MgO, 7 per cent SiO2, 6 per cent CaO and 6 per cent Fe203 + A1203. A sample of the reject material had the following analysis after calcining: 65.4 per cent MgO, 6.3 CaO, 21.1 SiO2 and 6.5 R2O3. The percentage reported as R2O3 includes compounds whose chlorides are acid-soluble but give precipitates in ammoniacal solution that are ignited and weighed. The more common constituents are Fe2O3, A1203 and TiO2. The sorted magnesite product is not the best grade. even for refractory purposes, and leaves much to be desired for a reduction process. The rejected material contains a large proportion of magnesite. It is apparent that an effective concentration method would yield a higher recovery and a better product. In general, the refractory grade is not suitably pure for other uses. Recent developments in the production of

Jan 1, 1943

By J. B. Clemmer, F. D. DeVaney, H. A. Doerner

Production of magnesium metal in the United States during the past decade has increased from less than 600,000 lb. in 1928 to more than 4,800,000 lb. in 1938.1 The growing industry has stimulated interest in methods of production and in sources of raw material. All of the present domestic production is from brines. However, the availability of large tonnages of magnesite in the state of Washington, together with the possibility of cheap power, have created interest in the utilization of magnesite for the production of magnesium metal as well as for other purposes. Magnesite, the carbonate of magnesium (MgCO3), usually is associated with limestone (CaC03) and dolomite (MgCO3. CaC03). It occurs in crystalline and microcrystalline (sometimes termed amorphous) forms.2 The more common crystalline mineral is found in various shades of white, gray, yellow and brown, the colors being due to impurities, chiefly iron. Magnesite has a hardness of 3.5 to 4.5 and a specific gravity of 3.0 to 3.1. It forms rhombohedra1 crystals in the hexagonal system, having a vitreous, pearly luster. The quarries and mines of the Northwest Magnesite Co. near Chewelah, Wash., are large producers of magnesite for refractories. The deposits are extensive, some veins being hundreds of feet wide. The boundaries of the veins are indefinite, and the magnesite is interfingered with dolomite. Calcite, talc, serpentine, quartz and shale are disseminated through the deposits. The quality of the ore cannot be determined by appearance or by simple tests; chemical analysis is required. These features make it difficult to determine the boundaries or total quantity of workable ore.3 Only the higher-grade ores are mined, and a considerable proportion of the magnesite content is discarded by hand-sorting and log-washing methods. After calcining, the sorted product meets the specifications for usual refractory material, as it contains approximately 81 per cent MgO, 7 per cent SiO2, 6 per cent CaO and 6 per cent Fe203 + A1203. A sample of the reject material had the following analysis after calcining: 65.4 per cent MgO, 6.3 CaO, 21.1 SiO2 and 6.5 R2O3. The percentage reported as R2O3 includes compounds whose chlorides are acid-soluble but give precipitates in ammoniacal solution that are ignited and weighed. The more common constituents are Fe2O3, A1203 and TiO2. The sorted magnesite product is not the best grade. even for refractory purposes, and leaves much to be desired for a reduction process. The rejected material contains a large proportion of magnesite. It is apparent that an effective concentration method would yield a higher recovery and a better product. In general, the refractory grade is not suitably pure for other uses. Recent developments in the production of

Jan 1, 1943

By Frederick Prime

The Great or Cumberland Valley, which (under a variety of names) extends from Canada, through Vermont, Massachusetts, Connecticut, New York, Pennsylvania, Maryland, Virginia, and East Tennessee, to Alabama, is composed in part of limestones lying immediately above the Potsdam sandstone. Geologically, they belong to the era between the Potsdam and Trenton, and are commonly termed Calciferous. A peculiarity of these limestones is their great richness in limonite or brown hematite ores, which form a large part of the charges of the many blast-furnaces situated on their outcrops. The mines from which the ores are obtained are (properly speaking) only pits or quarries, from which 'the ore is extracted by means of picks or shovels, powder being rarely employed. The ore does not occur casually at any point in the limestone, but forms regular lines, following apparently the outcrops of certain beds. In Lehigh County, Penn., where 1 have been engaged on the Geological Survey of the State, during the past season, there are three or four of these lines. During the progress of the survey I was much struck by the fact that the two most important and promising lines of outcrop were, one at the base of the crystalline schists (forming the South or Lehigh Mountain), and overlying the Potsdam sandstone conformably; the other, near the line of junction of the calciferous limestone with the slates of the Cincinnati epoch. The mines along these two lines, following the topography of the country, were in place, richer and more permanent than those of the belts between, which were generally leaner. A peculiarity of these two lines of outcrop, and one to which I particularly desire to draw attention, is the occurrence of what I at first mistook for a highly altered slaty limestone, but which subsequent analysis proved to consist in great part of damourite (hydrated potash mica). The following are analyses of this damourite slate: I. From Fogelsville, Lehigh County, within a few hundred feet of the contact of limestone and slate, by Dr. F. A. Genth. 11. From Hensingerville, Lehigh County, within 300 feet of gneiss, by Mr. Sydney Castle, of the University of Pennsylvania. 111. From Allentown, Lehigh County, within 150 feet of con

By AIME AIME

DREAMS do come true at times, although it is evidently better to believe in engineers than to "believe in fairies" if most dreams are to be translated into fact. It was a fine dream that David H. Moffat had when he projected a railway directly west from Denver; a dream of opening a new empire in northwestern Colorado, and of quickening transportation from the Middle West to the Pacific slope. But Moffat had been a miner and had become a banker. He knew that dreams, untranslated into works, benefit no one and pleasure only the dreamer, so he employed an engineer, H. A. Sumner, to study and plan the route to be followed by the rails. Previous main lines had run to the north, the Union Pacific, or the south, the Santa Fe. The Denver and Rio Grande, it is true, wriggled its way bravely across Colorado but, in order to reach a point 74 miles in an airline west of- Denver, travelled 281 miles following two canyons and crossing Tennessee Pass at 10,240 ft. Valuable as such a road is, it could never accomplish what Moffat had in mind. It was known that no low pass could be found directly west of Denver but up to 9000 ft. the topog-

Jan 1, 1925

By A. A. Burr, D. G. Ebeling

The effects of casting texture, grain orientation and grain size upon the performance of Alnico permanent magnets is described. Single-crystal specimens were produced by special sintering and grain coarsening techniques to study the effect of crystal orientation. In addition to texture and orientation effects, an analysis of the results indicates that the permanent magnet performance is impaired by a refinement of the grain size. AN excellent historical review of the development of Alnico permanent magnets has been prepared by Bozorth.1 The desirable permanent magnet characteristics of Fe-Ni-A1 alloys were discovered in 1932 by Mishima.2,3 The work of Ruder' showed that the alloys were age-hardenable, and Betteridge5 defined the best composition and heat treatment for the magnetically isotropic alloy known as "Alnico 3." Horsburgh and Tetley0 increased the energy product by the addition of cobalt and copper, "Alnico 2," and Oliver and Sheddon7 demonstrated that cooling in a magnetic field improved the residual induction of this alloy. Jonas8,9 then disclosed the great practical benefits of heat treating an alloy of higher cobalt content in a magnetic field and the resulting alloy, "Alnico 5," has become the standard of the industry. This paper describes the fundamental aspects of a procedure which can be used to further improve the properties of these anisotropic permanent magnet alloys. A study of the casting techniques used in the production of anisotropic Alnico permanent magnets indicated that the magnetic quality was affected by the as-cast macrostructure. Improved performance was observed in magnets containing a high percentage of columnar grains whose long axes were parallel to the magnetic axis of the casting. McCaig10 studied the effect of such columnar grain structures upon the magnetostriction characteristics of similar alloys, however no data was presented showing the effects on other magnetic properties. The following paragraphs describe two experiments which were conducted to determine the effect of various grain orientations upon the energy product. Special composite molds were prepared of highly conductive and highly refractive components to remove the heat of solidification from the casting in a controlled manner. Representative macrostructures produced by these techniques are shown in Fig. 1, along with the relative volumes of favorably oriented columnar grains. The alloy, Alnico 5, has the highest permanent magnet performance of any commercial magnet material. It has the nominal weight composition of 8 pct Al, 14 pct Ni, 24 pct Co, 3 pct Cu, and 51 pct Fe. A heat of this material was cast into molds producing the type A and B grain structures shown in Fig. 1 and pairs of the resulting magnets were placed in heat-treating boats so as to eliminate any biasing effects of boat position. After a standard heat treatment the type A magnets, with 16 pct of the volume composed of favorably aligned grains, had a maximum energy value of 3,940,000 gauss-oersteds, while the type B magnets with 73 pct aligned grains averaged 5,090,000. This large im-

Jan 1, 1954

By Benjamin L. Miller, Charles H. Breerwood

From earliest recorded times, limestone has been employed in the industrial life of peoples of all sections of the world where it exists. It is widely distributed and therefore has been available in almost every country and has been employed for a variety of purposes. Its earliest use was for buildings, since it is more easily quarried and dressed than most other kinds of rocks and so could be utilized by early inhabitants, poorly equipped with tools. The next use was in the manufacture of lime, which was employed by the ancients in mortar. These two uses of limestone are still all important, but they have been overshadowed in scores of regions by literally hundreds of new applications for raw limestone or products made from it. Anyone familiar with modern manufacturing processes can quickly call to mind many industries in which limestones are essential, and new uses are continually coming to notice. Any enumeration would probably be incomplete and soon out of date. Origin of Limestone Disregarding details and unusual types concerning which often there is insufficient evidence and considerable difference of opinion, limestones have been formed by the precipitation of calcium carbonate from solution through the action of organisms, both plants and animals, or in a limited number of instances by chemical reactions without the intervention of living forms. Some of the organisms extracted the calcareous material in order to build up hard structures, either as bony skeletons or as coverings (clams, snails, etc.), whereas others in their life functions emitted substances that resulted in the precipitation of the soluble constituents outside the organisms themselves. In some instances the organisms utilized only calcium carbonate but in some cases other compounds as well were precipitated. Various materials have been found in the hard parts of animals, and for that reason it is almost impossible to find a pure natural limestone; that is, one composed entirely of CaCO3.

Jan 1, 1938

By Charles H. Breerwood, Benjamin L. Miller

From earliest recorded times, limestone has been employed in the industrial life of peoples of all sections of the world where it exists. It is widely distributed and therefore has been available in almost every country and has been employed for a variety of purposes. Its earliest use was for buildings, since it is more easily quarried and dressed than most other kinds of rocks and so could be utilized by early inhabitants, poorly equipped with tools. The next use was in the manufacture of lime, which was employed by the ancients in mortar. These two uses of limestone are still all important, but they have been overshadowed in scores of regions by literally hundreds of new applications for raw limestone or products made from it. Anyone familiar with modern manufacturing processes can quickly call to mind many industries in which limestones are essential, and new uses are continually coming to notice. Any enumeration would probably be incomplete and soon out of date. Origin of Limestone Disregarding details and unusual types concerning which often there is insufficient evidence and considerable difference of opinion, limestones have been formed by the precipitation of calcium carbonate from solution through the action of organisms, both plants and animals, or in a limited number of instances by chemical reactions without the intervention of living forms. Some of the organisms extracted the calcareous material in order to build up hard structures, either as bony skeletons or as coverings (clams, snails, etc.), whereas others in their life functions emitted substances that resulted in the precipitation of the soluble constituents outside the organisms themselves. In some instances the organisms utilized only calcium carbonate but in some cases other compounds as well were precipitated. Various materials have been found in the hard parts of animals, and for that reason it is almost impossible to find a pure natural limestone; that is, one composed entirely of CaCO3.

Jan 1, 1938

By W. C. Ellis, E. S. Greiner, M. E. Fine

Discontinuous changes of Young's modulus, internal friction, coefficient of expansion, electrical resistivity, and thermoelectric power are evidence for a transition in chromium near 37OC. Although the X-ray diffraction pattern gives no clue, a difference between the thermal expansivity and the temperature dependence of the lattice parameter suggests a crystal-lographic change. Young's modulus data disclosed another transition near THE thermal dependence of a number of proper- ties of chromium indicates a transition occurring over a temperature range near room temperature. Bridgman' noted this first from a minimum in the electrical resistivity near 12°C. In a sample of greater purity, Sochtig' observed the minimum at 41 °C. Erfling3 reported an inflection in the thermal expansivity curve at 36°C. These temperature-dependence curves are reversible with no hysteresis being detected. No discontinuity or inflection has been observed in the heat capacity' or the paramagnetic susceptibility.' Likewise, no one has noted a change in crystal symmetry. In the present investigation Young's modulus, internal friction, coefficient of expansion, electrical resistivity, illustrated in Fig. 1, lattice constant, Fig. 2, thermal electromotive force, Fig. 3, and paramagnetic susceptibility, Fig. 4, were measured over an extended temperature range. The samples were prepared in two ways: (1) By cold pressing a sintered electrolytic powder compact,' and (2) by electroforming from an aqueous solution. The electroformed samples were prepared by R. A. Ehrhardt and G. Bittrich by plating on copper or nickel tubes from an aqueous solution according to the method of Brenner, Burkhead, and Jennings.' The pressed powder samples (method 1) were finally annealed at 1400°C in purified helium: the electroformed samples, packed in powdered chromium, were vacuum-annealed at 1000°C. From the composition of the original powder' the purity of the pressed powder samples is estimated to be 99.8 pct Cr. Spectrochemical analysis furnished by E. K. Jaycox, revealed only slight traces of impurities in the electroformed sample (less than 0.001 pct), neither iron nor nickel being detected. Chromium deposited by this method is reported to contain approximately 0.05 pct 0.- Methods and Data Young's Modulus: For measurement of Young's modulus, an annealed, pressed powder sample, 0.114 x0.237x1.845 in., and an electroformed sample, 0.10 in. od, 0.01 in. id, and 1.86 in. long, were prepared. The resonant frequencies of the rod samples in forced longitudinal vibration were measured at a series of temperatures from —192" to 200°C by a method previously de~cribed.6,7 Because the samples were nonferromagnetic, iron- silicon or molybdenum permalloy tips (0.013 in. thick) were soldered to the ends. The softening temperature of the solder limited the temperature of measurement. Young's modulus, E,, of chromium at temperature, T, may be calculated from the resonant frequency of the composite rod, f,; the thickness of the tips, t; the length of the chromium sample at 25°C, l,.; the density of chromium at 25°C, pc (7.20 g per cc);5 and the thermal expansivity, Al/l25. Modulus differences for two temperatures, ET and E, are accurate to +0.002x10" dynes per cm2. ET = 4PAlc+2tyf Young's modulus at 25°C, Fig. la, is 28.2~10" dynes per cm' (40.8xlO" si) in wrought chromium (upper curve). The modulus of the electroformed sample is apparently lower due to cracks. From the modulus measurements two transitions were observed: one with a critical temperature at 37°C, the other at —152°C. Internal Friction: The internal friction, 1/Q, was determined from the width, Af, of the strain amplitude-frequency curve at 0.707 times the strain amplitude at resonance;' the internal friction, 1/Q, then equals Af/f. Fig. lb shows a sharp peak in internal friction at 38°C. The internal friction of the electroformed sample had a similar maximum. Thermal Expansion: The expansivity measurements, shown in Fig. 2, covering the temperature range —195" to +400°C were made by D. MacNair in an interferometric dilatometer8 sing a sample consisting of three pyramids 0.25 in. high prepared from wrought electrolytic chromium. Below —120°C the experimental points deviated up to ±2x10 from the drawn expansivity curve in Fig. 2 because of decreased precision of the quartz wedge thermometer at low temperatures. Near 38°C the thermal expansivity curve, Fig. 2, goes through an inflection corresponding to a minimum in the coefficient of expansion, Fig. ld, and a relative volume decrease on heating. Electrical Resistivity: The variation of electrical resistivity with temperature measured by the po-tentiometric method is also shown in Fig. l. The resistivity of the wrought chromium (upper curve) at 20°C is 13.6 microhm-cm; of electroformed chromium (lower curve) 12.8 microhm-cm. The lower value reflects higher purity and agrees closely with a published value." A minimum at 40°C occurs in the resistivity curves of both samples. No conclusive evidence for a transition near — 150°C was observed, but the points, Fig. 1, appear to deviate from a smooth curve between —120" and —160°C.

Jan 1, 1952

By A. E. Brugger

SOME 2,000 years ago Pliny is supposed to have said, "Out of Africa always something new." It may perhaps even now be news to a great many that the Belgian Congo has in recent years been producing approximately a quarter of a ton of diamonds annually. For that is what the 1 1/4 million carats, the recovery from 40-odd operating mines, and about 20 or 25 per cent of the world's normal consumption, amounts to. In 1915, first exploitation operations produced less than 50,000 carats from two mines. The rapid expansion of operations following the Euro¬pean war meant a most rapid development of a virgin land. The interior is now reached by air in one day from the mouth of the Congo River, where steamers unload mail and passengers from Antwerp. This trip formerly consumed 4 to 6 weeks by a narrow-gage, wood-burning, railroad around the rapids of the lower Congo and Livingston Falls; by river boat to the heads of navigation, Djoko Punda on the Kasai or Luebo on the Lulua; and thence by caravan of native porters over narrow-trails to head¬quarters on the Tshikapa. Hundreds of miles of automobile roads have been constructed over veldt and through forest, bridging streams and ferrying rivers. The railway from Capetown to the Katanga copper district to the East, once two months away by trail is now reached in 2 or 3 days over fair automobile highway. Native "boys" who a few short years ago wore little more than a smile and a string of beads and to whom a wheelbarrow was a complicated piece of machinery, are today driving Fords, tending boilers and engines and operating electrical equipment, or are capable mine workmen, machinists and artisans, and dressed in all manner of cast-off white man's clothing. Even as late as 1920, due to difficulties of securing and transporting machinery during and just after the war, the crudest hand operations were the rule for the excavation, sizing, and concentration of the diamondiferous gravel. All washing and concentration is now mechanized, using steam or electric power, and where operations are sufficiently large to permit competition with native labor costs, excavation and transportation are also accomplished by machinery.

Jan 1, 1932

By F. Clerf

Blast-furnace practice in France is determined more or less by the character of the ores used. Some French ores are siliceous and others are calcareous, therefore by proper burdening a self-fluxing mix can be used. This is not always done, as, for instance, at the Caen furnaces of the Société Métallurgique de Normandie, where the Soumont ore of Normandy is used, which is a carbonate. This ore is crushed and calcined at the mines, yielding a product that is porous and well sized for blast-furnace consumption. The lines of the Caen furnaces are given in Fig. 1. Originally these furnaces had 16 tuyeres; six are plucked and these tuyeres are set in the lower part of the bosh. Operating data on these furnaces are given in Table 1. Table 1.—Operating Data, Caen Furnaces Kg. Lb. Blast-furnace burden per ton of iron: Soumont ore....................................... 200&2100 (44004650) Limestone...................................... 900-1000 (2000-2200) Basic Bessemer slag (bearing phosphorus).............. 100 (220) Scale.............................................. 35 (77) Manganese ores.................................... Coke.............................................. 1100-1200 (2420-2640) Coke analysis: Ash, per cent............. 9.5 H2O, per cent............. 4.0-10.0 Flue dust (approx.), kg. per metric ton.... 200 (440 lb.) Blast volume, cu. m. per hr.............. 83,000 (49,000 cu. ft. per min.) Preesure, lb............................ 12 Blast heat, deg. C....................... 650 (1200" F.) Top temperature, deg. C................ 250 (445O F.) Top-gas analysis, per cent............... CO2 9.3 CO 30.3 O2 0.3 H2 3.0 Production per 24 hr. about 510 tons. MINETTE ORES The most important ore deposits in France are in the west of Lorraine. They are called the "minette" ores and are of two classes-—siliceous and

Jan 1, 1937

By D. B. Williams

For the first time in the history of the Venezuelan petroleum industry production exceeded 200 million barrels. The total production for all fields amounted to 205,430,869 bbl., which is more than 9 per cent of the world's 1939 total. This is an increase of over 15 million barrels or 8.0 per cent above the 1938 figure, which, compared with the slightly less than 2 per cent increase of the 1938 figure over 1937, shows the marked activity in Venezuela during the past year. The Maracaibo Lake fields are still the predominating factor in Venezuelan production, showing an increase of approximately 9½ million barrels over last year's figure and accounting for 71.8 per cent of Venezuela's total. Lagunillas continues to hold precedence as a single field, having yielded 47.1 per cent of the accumulative total and 39.4 per cent of 1939's total. This field showed an increase of slightly more than 3½ million barrels over 1938. Tia Juana, the second largest field, attained a record production, increasing its percentage of the Venezuelan total from 23.4 in 1938 to 23.7 in 1939. The La Rosa field, which includes Punta Benitez and Ambrosio, declined from 13.7 to 12.0 per cent; Bachaquero, the southernmost Lake field, which came into regular production at the end of 1938, contributed over 31/3 million barrels. Quiriquire, in eastern Venezuela, ousted La Rosa as the third largest producing field, and, although production increased by 11/3 milliorl barrels, percentage of the total declined from 13.2 to 12.9. Mene Grande, the oldest field, declined from 6.6 per cent in 1938 to 5.9 in 1939. Tem-blador produced for a whole year for the first time and yielded 3,647,867 bbl. The Colon district, in the Maracaibo Lake area, comprising the Tarra-Los Manueles fields, showed slight increases, as also did Cumarebo and Pedernales. Construction of the 16-in. pipe line from Oficina to Puerto La Cruz (Guanta), the longest line of this size in the world, was completed toward the end of the year and this new field in eastern Venezuela started shipping oil in December. This field is operated by the Mene Grande Oil Co. and was credited with a production of 2,347,625 bbl. in 1939. Jusepin field, some 25 miles southwest of Quiriquire in eastern Venezuela,

Jan 1, 1940

By D. B. Williams

For the first time in the history of the Venezuelan petroleum industry production exceeded 200 million barrels. The total production for all fields amounted to 205,430,869 bbl., which is more than 9 per cent of the world's 1939 total. This is an increase of over 15 million barrels or 8.0 per cent above the 1938 figure, which, compared with the slightly less than 2 per cent increase of the 1938 figure over 1937, shows the marked activity in Venezuela during the past year. The Maracaibo Lake fields are still the predominating factor in Venezuelan production, showing an increase of approximately 9½ million barrels over last year's figure and accounting for 71.8 per cent of Venezuela's total. Lagunillas continues to hold precedence as a single field, having yielded 47.1 per cent of the accumulative total and 39.4 per cent of 1939's total. This field showed an increase of slightly more than 3½ million barrels over 1938. Tia Juana, the second largest field, attained a record production, increasing its percentage of the Venezuelan total from 23.4 in 1938 to 23.7 in 1939. The La Rosa field, which includes Punta Benitez and Ambrosio, declined from 13.7 to 12.0 per cent; Bachaquero, the southernmost Lake field, which came into regular production at the end of 1938, contributed over 31/3 million barrels. Quiriquire, in eastern Venezuela, ousted La Rosa as the third largest producing field, and, although production increased by 11/3 milliorl barrels, percentage of the total declined from 13.2 to 12.9. Mene Grande, the oldest field, declined from 6.6 per cent in 1938 to 5.9 in 1939. Tem-blador produced for a whole year for the first time and yielded 3,647,867 bbl. The Colon district, in the Maracaibo Lake area, comprising the Tarra-Los Manueles fields, showed slight increases, as also did Cumarebo and Pedernales. Construction of the 16-in. pipe line from Oficina to Puerto La Cruz (Guanta), the longest line of this size in the world, was completed toward the end of the year and this new field in eastern Venezuela started shipping oil in December. This field is operated by the Mene Grande Oil Co. and was credited with a production of 2,347,625 bbl. in 1939. Jusepin field, some 25 miles southwest of Quiriquire in eastern Venezuela,

Jan 1, 1940

By D. Kramer

HASEN1 has published a phase diagram for the zirconium-nickel system. This phase diagram has been redetermined by Hayes, Roberson, and paasche2 in the range 0 to 50 at. pct Ni. Recently, Smith and Guard3 have published a tentative diagram for the

Jan 1, 1960

By Thomas A. Edison

We have not yet begun. to realize the possibilities of automatic machinery, in part because we have not developed the designing brains, and in part because we have not sufficiently simplified industry to make possible the economical use of such machinery. The principle of the Jacquard loom, has scarcely been utilized except in weaving silk and in the player piano. It is the principle of bringing into action the various parts of a machine in accordance with a pattern traced on a steel card by perforations or as on the paper roll of a player piano. This principle gives us a control which can be applied to any kind of machine. It is a' great reserve principle for the future. But even now, with the machinery that we have at command, anyone can cut the number of employees in two, at the same time doubling his output, by installing semi-automatic or automatic machinery. And no one knows how far this process can go on. Cutting down the number of men is not just putting some poor fellows out of a job. It is increasing the number of good jobs by increasing the production per capita to a point where really satisfactory wages can be paid out of it, and this in turn- increases the amount of work required to be done and creates new jobs. Thus, cheapening in- creases the demand.

Jan 1, 1929

By C. C. Wright, T. S. Spicer, R. G. Bowman

In recent years considerable publicity has been given to the problem of atmospheric pollution by fuel-burning equipment. Legislation has been stimulated and smoke ordinances have been enacted, the provisions of which show a definite trend toward stricter control of the emissions not only from the stacks of industrial fuel users but also from the chimneys of domestic consumers. As a result of war conditions, some slackening in the enforcement of these ordinances may be noted, but this is only a temporary expediency caused by the changes necessary in the distribution of the nation's fuel supplies and difficulties in securing the necessary equipment. Previous trends may be expected to continue in the postwar period. Largely because of the consumer demand for automatic heat, but partly because of the legislation against smoke emission, there has been a marked increase in the use of domestic underfeed stokers with the past decade. When correctly adjusted and operated, these units reduce the smoke emission materially, so that even the high-volatile bituminous coals may be burned with little or no emission of objectionable smoke. Unfortunately, however, the use of the domestic underfeed stoker introduces another problem; namely, fly-ash. Production of Fly-ash The term "fly-ash" is a misnomer, since the fly material is generally a mixture of small carbonaceous particles varying from green coal to coke, and inorganic particles ranging from fluffy ash to small particles of fused clinker. For want of a more comprehensive name, however, the term fly-ash is used throughout this paper to include all the fly material. Even with hand-fired furnaces a certain amount of fly-ash is produced, which necessitates periodic cleaning of the boiler flues or furnace radiator, the smoke pipe, and occasionally the chimney itself. With stoker operations the amount of fly-ash is increased many fold, because of the higher velocity of air travel through the fuel bed. Frequently the amount of this fly-ash attains such proportions as to constitute a definite nuisance to the householder and his neighbors and distracts very materially from the otherwise automatic or semi-automatic performance of the stoker. Virtually all the boilers and hot-air

Jan 1, 1944