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By Aloys IL. Wollrab

The conditions that govern the selection of a suitable type of detachable bit for the small, isolated mine, for rock work and tunnel contracting and for the large mine are quite dissimilar, therefore intelligent recommendation of a particular make of detachable bit must involve consideration of many factors. Small, isolated mines may find advantageous a detachable bit that a larger mine cannot afford to use, because of more efficient conventional steel sharpening and steel-distribution practice, but a small mine may not be able to adopt the practice of large mines because of necessary capital expenditures for equipment for detachable-bit sharpening and . shanking. The perfect detachable bit, suitable for all conditions, has not yet been developed. Conventional Drill Bit in Use That drilling speed increases as the bit gauge decreases is well known, but since small-hole drilling is the exception rather than the rule the rate of such increase is probably not so generally recognized. Tests carried out by Holman Brothers Limited1 with 7/8-in. steel show that when bit sizes are reduced from I½ in., I3/8 in., and I3/16 in-; to I3/8 in., I1/4 in.., and I1/8 in., respectively, the volume of the hole is I 5 per cent less and the drilling speed 49 per cent higher. Recent tests by the United States Bureau of Mines2,3 in hard, uniform basalt showed that a reduction in average gauge from 2.077 to I,826 in., a difference of o.25I in., gave an increased drilling speed of 65 per cent. The limits to which a drill hole may be extended depend upon the loss in gauge. Since the conventional bit with 5° and 14° clearances did not possess sufficient reaming edge to permit the smaller gauge changes that were required for small-hole drilling, experiments were made in bit construction with a view to correcting this deficiency. This resulted in the adoption of the full reaming cross bit (having full Carr charac1erist.i~~) by some mines4 In order to drill holes having a minimum taper from the collar to the bottom of the hole, full reaming center-hole cross bits with 90° cutting angles, 5° and 14° wing tapers, forged on 7/8-in. quarter-octagon drill rods, are used in the conventional drill-steel practice at Hollinger. In the steel shop close attention is given to the condition of the dies and dollies, which, combined with a rigid inspection of the finished bit, ensures as nearly a perfect bit as call be forged economically. Shop practices and costs have been discussed in earlier paper.5,6 The method by which the radii for the special dies used for forging bits of different gauge diameter are obtained so that the points and reaming edges cut circles of the same diameter has been discussed by Hibbert. Requiremnts for Detachable. Bit for Hollinger Under these it it was appar- ent that it would be difficult to introduce a detachable bit that could successfully compete with the conventional bit already in

Jan 1, 1943

By W. W. Weigel

THE mines of the St. Joseph Lead Co. in St. Francois County, Missouri, form a roughly triangular area of about 45 square miles. Locally this is known as the Lead Belt. The four operating mines in the area at present are the Federal, Leadwood, Desloge, and Bonne Terre, in decreasing order of mine area and daily production. Mining began in 1864 and has been carried on in the district continuously since that time. [ ] As a group, the Lead Belt mines now handle 20,000 gal. per min. of water, average head about 465 ft., against a normal daily ore tonnage of 21,200 tons. For a six-day operating week this gives a ratio of 6 ½ tons of water per ton of ore. Total average pumping in 1931 was about 15,000 gal. per min. Since that time a large area of virgin territory has been opened, much of which has had temporary flush flows. About 75 per cent of the water enters in certain restricted very wet areas. Production figures are given in Table I. The figures by divisions for 1931 and 1941 are not exactly comparable, as there were several transfers of pumping loads from one division to another during that period of time. GEOLOGY The basement formation in the Lead Belt area consists of the pre-Cambrian rhyolite porphyry and granite. Overlying this is the La Motte sandstone, of Middle Cambrian age, which offers a good medium for circulation of water. It varies in thickness up to 400 ft. Above this is the Bonne Terre dolomite, approximately 375 ft. thick, which in turn is overlain by the 150-ft. Davis shale. The formations above this, present in the Lead Belt in small areas only, are of minor importance. The ore bodies occur as large, horizontal tabular masses or as long, narrow runs; they are found throughout the Bonne Terre but largely in the lower 150 ft. The rather indefinite contact with the La Motte is a favorite ore horizon. Mining is entirely by open stope and pillar breast systems. To the south, west, and north of the district, sandstone outcrops are few and limited. Heavy faulting bounds the district on those sides and probably there is little if any artesian circulation from those directions. To the east, the La Motte rises to an outcrop area of about 40 square

Jan 1, 1943

By Luis Toron, Salvador Cortes-Obregon

John D. Price (Colorado Fuel and Iron Corp., Pueblo, Colo)—The paper on the coal fields of the Oaxaca district as prepared by engineers Toron and Cortes-Obregon of the staff of the Bank of Mexico bears witness to the thorough and careful way in which the men associated with this organization perform their work. There is little to be added to their paper in way of discussion other than to confirm and amplify some of their statements. Since the only extensive and well-developed field of coking coal lies in the northeastern section of the country adjacent to Sabinas in the state of Coahuila, it follows that blast furnace plants would be located in that same region. Two such plants are now operating at Monterrey and Monclova, using coke produced at the Sabinas district mines. But the nearer of these two plants is 600 miles from Mexico City and even farther from the center of population. Transportation of products from these mills to the market area is therefore expensive, both because of the distance and the difficulty of the terrain over which it must be carried. The development of an integrated steel industry closer to the center of population has therefore long been a goal toward which the Mexican technicians have been striving. While the presence of coal of some grade has been reported in many of the states, and many ideas have been advanced regarding its possible uses in iron and steel production, deposits of anthracite in Sonora and the various coals of the Oaxaca district as reported on in this paper are the only ones that have been explored in a serious manner. The coking coal from the Mix-tepec zone appears to offer promise of producing a coke which could be used in a standard blast furnace. Several problems are indicated, however: 1—The ash in the coal is high as mined, but indications are that it can be washed to an ash content of 15 pct with a recovery of 70 pct of washed coal. 2—Such washing would increase the volatile content from 17.4 pct to about 20 pct, and in a byproduct oven this should give a coke yield of close to 80 pct with an ash content of coke under 20 pct. 3—A free swelling index of 5 appears low for a good coking coal, and below that of the coals from the Sabinas district, which show between 6 and 9. But washing of the coal should result in an improvement in this regard; in the United States coals from Utah with an index even lower than 5 have made a usable coke. 4—A coal with volatile as low as 17.4 in raw coal and 20 in washed coal would come close to being classed as a low-volatile rather than medium-volatile coal, and low-volatile coals are notorious for their high expansion properties. Several plants in the United States are making coke from straight medium-volatile coal of 26 to 28 volatile content, and one at Rosita,, Mexico, from coal of 25 volatile. But no plants to my knowledge are using coal as low as 20 volatile. Since the Rosita coal appears to be a borderline coal from the angle of its expansion properties the coking of one of the straight lower volatile must be approached with caution. 5—There are few coals possessing any degree of coking properties which cannot be used in coke production by careful attention to its preparation and blending. The fact that coals of other types are available in this same region make improvement through blending very possible. 6—There are other workable methods of reducing iron ore other than the conventional coke-blast-furnace method. These will not be discussed here but it is known that their use has been considered. The technicians of not only Mexico but also of the other Latin American countries are keenly aware of their natural resources and their national needs. This paper emphasizes the fact that the Mexican technicians are working on their problem and attempting to speed the day of self-sufficiency for their country. Salvatore Cortes-Obregon (author's reply)—I wish to thank Mr. Price for his kind remarks. The Mixtepec coal as shown in Table II has 30 pct ash and a free swelling index of 5, but when the same coal is washed to 15 pct ash it has a free swelling index of 8 to 9 and the volatiles increased from 17.4 to 20.7 pct. A satisfactory coke has been produced from blends made in the Mexican laboratory using at least 40 pct of the Mixtepec coking coals with the other Oaxaca non-coking coals. Koppers in Germany report good coke obtained from the Oaxaca coal with a blend of 80 pct Mixtepec coal. Consideration is being given the possibility of using methods other than the conventional blast furnace for the reduction of iron ore near the Oaxaca area; electric furnaces appear promising. The non-coking coals could be used to produce cheap electric energy and the coking coals to make metallurgical coke.

Jan 1, 1955

By W.W. Weigel

The mines of the St. Joseph Lead Co. in St. Francois County, Missouri, form a roughly triangular area of about 45 square miles. Locally this is known as the Lead Belt. The four operating mines in the area at present are the Federal, Leadwood, Desloge, and Bonne Terre, in decreasing order of mine area and daily production. Mining began in 1864 and has been carried on in the district continuously since that time. As a group, the Lead Belt mines now handle 20,000 gal. per min. of water, average head about 465 ft., against a normal daily ore tonnage of 21,200 tons. For a six-day operating week this gives a ratio of 6½ tons of water per ton of ore. Total average pumping in 1931 was about 15,000 gal. per min. Since that time a large area of virgin territory has been opened, much of which has had temporary flush flows. About 75 per cent of the water enters in certain restricted very wet areas. Production figures are given in Table I. The figures by divisions for 1931 and 1941 are not exactly comparable, as there were several transfers of pumping loads from one division to another during that period of time. Geology The, basement formation in 'the Lead Belt area consists of the pre-Cambrian rhyolite porphyry and granite. Overlying this is the La Motte sandstone, of Middle Cambrian age, which offers a good medium for circulation of water. It varies in thickness up to 400 ft. Above this is the Bonne Terre dolomite, approximately 375 fl. thick, which in turn is overlain by the 150-ft. Davis shale. The formations above this, present in the Lead Belt in small areas only, are of minor importance. The ore bodies occur as large, horizontal tabular masses or as long, narrow runs; they are found throughout the Bonne Terre but largely in the lower 150 ft. The rather indefinite contact with the La Motte is a favorite ore horizon. Milling is entirely by open stope and pillar breast systems. To the south, west, and north of the district, sandstone outcrops are few and limited. Heavy faulting bounds The district on those sides and probably there is little if any artesian circulation from those directions. To the east, the La Motte rises to an outcrop area of about 40 square

Jan 1, 1943

By W. W. Weigel

The mines of the St. Joseph Lead Co. in St. Francois County, Missouri, form a roughly triangular area of about 45 square miles. Locally this is known as the Lead Belt. The four operating mines in the area at present are the Federal, Leadwood, Desloge, and Bonne Terre, in decreasing order of mine area and daily production. Mining began in 1864 and has been carried on in the district continuously since that time. As a group, the Lead Belt mines now handle 20,000 gal. per min. of water, average head about 465 ft., against a normal daily ore tonnage of 21,200 tons. For a six-day operating week this gives a ratio of 6½ tons of water per ton of ore. Total average pumping in 1931 was about 15,000 gal. per min. Since that time a large area of virgin territory has been opened, much of which has had temporary flush flows. About 75 per cent of the water enters in certain restricted very wet areas. Production figures are given in Table I. The figures by divisions for 1931 and 1941 are not exactly comparable, as there were several transfers of pumping loads from one division to another during that period of time. Geology The, basement formation in 'the Lead Belt area consists of the pre-Cambrian rhyolite porphyry and granite. Overlying this is the La Motte sandstone, of Middle Cambrian age, which offers a good medium for circulation of water. It varies in thickness up to 400 ft. Above this is the Bonne Terre dolomite, approximately 375 fl. thick, which in turn is overlain by the 150-ft. Davis shale. The formations above this, present in the Lead Belt in small areas only, are of minor importance. The ore bodies occur as large, horizontal tabular masses or as long, narrow runs; they are found throughout the Bonne Terre but largely in the lower 150 ft. The rather indefinite contact with the La Motte is a favorite ore horizon. Milling is entirely by open stope and pillar breast systems. To the south, west, and north of the district, sandstone outcrops are few and limited. Heavy faulting bounds The district on those sides and probably there is little if any artesian circulation from those directions. To the east, the La Motte rises to an outcrop area of about 40 square

Jan 1, 1943

By M. C. Udy, F. W. Boulger

AN incomplete phase diagram for the U-Ti systern was determined earlier 1 and more recently, a tentative diagram was presented for the uranium-rich end of the system.' In the present re-examination of the whole system of U-Ti alloys, high purity materials were used. Melting stock for the alloys was high purity uranium, containing about 0.09 pct C as the only appreciable impurity, and high purity iodide-process titanium purchased from New Jersey Zinc Co. Both metals were cold rolled to about 1/6 in. thickness, sheared to about I/' in. squares, and cleaned by pickling. The alloys were arc melted under a helium atmosphere in a water-cooled copper crucible. A thoriated-tungsten electrode was used. The furnace chamber was evacuated, then flushed with helium, prior to each melting. It was finally filled with stagnant helium at one atmosphere pressure. Each alloy was remelted three times after the original melting, to insure homogeneity. The alloy button was turned bottom side up before each re-melting operation. Some 22 alloys were examined. Their compositions were spaced at appropriate intervals between 100 pct Ti and 100 pct U. Analyses were made on chips taken after fabrication. The major contaminant was carbon, which varied from 0.03 to 0.08 pct. It appeared in the microstructure as titanium carbide. Alloy compositions were calculated to a carbon-free basis for consideration on the diagram. Tungsten and copper, possible contaminants from the melting operation, were generally less than 100 parts per million each. Fabrication All alloys were forged and rolled to bars approximately V8 in. square. They were clad either in SAE 1020 steel or in a 5 pct Cr-3 pct Al-Ti-base alloy, depending on the fabrication temperature. A temperature of 1800°F (980°C) was used for alloys near the compound composition. This necessitated using the titanium-base alloy, since iron reacts with titanium at this temperature, producing a low melting alloy. Other alloys were fabricated at 1450°F (790°C), using steel jackets. No iron-titanium reaction occurred at this temperature. The jackets were welded in place in an argon atmosphere. Those alloys sheathed in steel were declad and then reclad between rolling and forging operations. On the other hand, those clad with the titanium alloy were cut to a roughly rectangular shape prior to clading and were then carried through both the forging and rolling operations without opening. Those alloys near the compound composition were found to be cracked when the clading was removed. The cracked materials had been plastically deformed, however, and at least some of the cracking had OCcurred during cooling. Heat Treatment The rolled bars, after being declad and shaped to remove surface contamination, were all given an homogenizing treatment of 160 hr at 2000°F. (Samples were taken for analysis following the declading and shaping operations.) All were heat treated at the same time in one furnace, but each was sealed in a purified argon atmosphere in an individual Vycor glass tube. Argon pressure was such that it was approximately atmospheric at temperature. One end of each tube contained titanium chips and this end was heated to 1200°F (650°C) for 10 min prior to the heat treatment. This purged the atmosphere of residual reactive gases. The balance of the tube was warmed during the purge to liberate adsorbed moisture and gases, which also reacted with the hot chips. The bars were furnace cooled from the homogenization treatment. Specimens of each alloy were water quenched after 2 hr heating at 1000°, 1200°, 1400°, 1600°, 1800°, and 2000°F (540°, 650°, 760°, 870°, 980°, and 1095°C). In addition, some were treated at intermediate temperatures of 1300°, 1500°, and 1700°F (705", 815", and 925°C) and at 2150°F (1175°C). Specimens, about '/s in. cubes, were cut from the bars, sealed in individual Vycor tubes, and heat treated as described. All specimens heat treated at the same temperature were processed together. Samples were quenched by breaking the Vycor tube rapidly under water. Metallographic Examination Specimens were mounted in bakelite and ground wet on 180 grit paper held on a 1750 rpm disk. They were then ground wet by hand, using 240, 400, and 600 grit papers. The rough grinding was continued long enough to get well below the surface. Specimens were mounted separately because of the variation in the rate of etching between alloys. The specimens were polished with rouge on a 4 in., 1725 rpm wheel covered with Miracloth. Alloys on the titanium side of the compound composition were etched with a solution of 2 pct hydrofluoric acid in water saturated with oxalic acid. A few crystals of ferric nitrate were added as a bright -ener. Specimens were immersed 5 sec, polished to remove the etch, then re-etched. With the higher titanium alloys, it was often necessary to start the etch on the polishing wheel, because of the formation of a passive film. In some instances, a plain 2 pct hydrofluoric etch was satisfactory. For the alloys on the uranium side of the compound, a distinction between the compound and the uranium phase developed after standing a short time in air. This could be hastened by the application of heat, such as obtained by placing the specimen on a radiator. A deep etch was necessary to develop details in the uranium-rich phase, such as the Widmanstaetten pattern sometimes obtained by quenching y uranium. A 2 pct hydrofluoric acid solution was used for this deep etching.

Jan 1, 1955

By E. H. Dix

During an investigation of high-strength manganese bronze by til Engineering Division of the Air Service, at McCook Field, Dayton, Ohio, particles of a "blue constituent" were noted in the microstructure of most of the bronzes examined. The constitution of the simple copper-zinc base alloy is still a matter of dispute in spite of the fact that the copper-zinc series is one of the oldest industrially important groups of alloys, and has received thc carly co~l+itlcl-ntio11 of scirntific rcsc:trch. Thc diagram, according to the rnost rcrent \vork.' IS shown in Fig. 1. The disputed questions involve the tcrmi~r:~tiorl of the beta field and the lint at 470' C. The parliest expc~imc>ntcr, Rol)erts--~1~11stcri, detectrd an arrest in some of his cooling curves :it approximately this temperature and ascribed them to the formation of a cutectic; it has since been proved that there arc no eutectics in this series. Shepherd? was unable to detect any thermal arrests at this temperature, his. diagram was essentially as shown in Fig. 1, except that the line at 470" ('. was omitted and the beta phase carried down to normal temperature. 1,:ttcr. carpenter and Edwards, by a very painstaking research, definitely established the authenticity of the line but attributed it to the breakdown of the BETA constituent into a cutectoid of alpha and gamma. microscopic evidence of the formation of the cutectoid is doubtful and it seems more likely to he due to an allo-tropic change in the beta constituent as shown by Fig. 1. At least for practical purpose?, it is more convenient to think of the structure of a 60-40 brass as a mixture of alpha and beta prime crystals rather thin alpha plus an unresoluble eutectoid of "apparent beta" as it has often been called. * Chief, Metals branch, Engineering Division, Air Service. 1 0. F. Hudson: Jnl. Inst. of hlvtals (1913) 12, 2 E. S. Shepherd: Jnl. Phys Chrm. (10141 8, 421. H. C. H. Carpenter and O. A. Edwards: Jnl, Inst. of Metals (1911) 5, 127.

Jan 1, 1923

By E. H. Dix

During an investigation of high-strength manganese bronze by til Engineering Division of the Air Service, at McCook Field, Dayton, Ohio, particles of a "blue constituent" were noted in the microstructure of most of the bronzes examined. The constitution of the simple copper-zinc base alloy is still a matter of dispute in spite of the fact that the copper-zinc series is one of the oldest industrially important groups of alloys, and has received thc carly co~l+itlcl-ntio11 of scirntific rcsc:trch. Thc diagram, according to the rnost rcrent \vork.' IS shown in Fig. 1. The disputed questions involve the tcrmi~r:~tiorl of the beta field and the lint at 470' C. The parliest expc~imc>ntcr, Rol)erts--~1~11stcri, detectrd an arrest in some of his cooling curves :it approximately this temperature and ascribed them to the formation of a cutectic; it has since been proved that there arc no eutectics in this series. Shepherd? was unable to detect any thermal arrests at this temperature, his. diagram was essentially as shown in Fig. 1, except that the line at 470" ('. was omitted and the beta phase carried down to normal temperature. 1,:ttcr. carpenter and Edwards, by a very painstaking research, definitely established the authenticity of the line but attributed it to the breakdown of the BETA constituent into a cutectoid of alpha and gamma. microscopic evidence of the formation of the cutectoid is doubtful and it seems more likely to he due to an allo-tropic change in the beta constituent as shown by Fig. 1. At least for practical purpose?, it is more convenient to think of the structure of a 60-40 brass as a mixture of alpha and beta prime crystals rather thin alpha plus an unresoluble eutectoid of "apparent beta" as it has often been called. * Chief, Metals branch, Engineering Division, Air Service. 1 0. F. Hudson: Jnl. Inst. of hlvtals (1913) 12, 2 E. S. Shepherd: Jnl. Phys Chrm. (10141 8, 421. H. C. H. Carpenter and O. A. Edwards: Jnl, Inst. of Metals (1911) 5, 127.

Jan 1, 1923

By Koert D. Burnham, John G. Broughton

WOLLASTONITE in Essex County, New York, occurs as a typical contact mineral in a series of rocks metamorphosed by anorthosite. Sole current use is in various types of electric welding fluxes. Its uniform lathlike shape suggests its use as a specialized filler.

Jan 1, 1944

By R. A. Kinzie

THE major operating costs in a cement plant are labor, power, and fuel. The opportunities and methods of savings in labor and power parallel other industries. Because our industry's use of fuel is large and its method of use is unique, the devices adapted for saving fuel are of interest. In normal practice the raw material in the form of a dry powder or a mud is fed to a rotating inclined cylinder where it is dried, calcined, and clinkered. In a Lepol kiln the raw material is rolled up into little balls with water in the nodulizer, fed to a traveling grate on which it is dried and partially calcined and tben to a short kiln where the process is finished. The more usual methods of saving heat have been the use of long kilns with chains in wet process plants and the use of waste heat boilers in dry plants (fig. 1). At the Santa Cruz plant we have used a Lepol system kiln and achieved a fuel 'economy of 4.7 gal per bbl of clinker or about 704,-000 Btu per bbl. This can be compared with our old kilns using the same fuel and raw material which consume 7.8 gal per bbl or 1,130,000 Btu per bbl. These are gross Btu and not the net figures usually used in reports of foreign companies. Our average consumption for 1948 was 708,000 Btu per bbl of Lepol clinker, based on cement sold, and oil purchased. The overall fuel consumption for 1948 was 6.61 gal per bbl. The Lepol system consists of a nodulizer, a grate, and a kiln. There is the usual accessory equipment which is similar to that used in other cement plants. The following description covers the equipment in operation at our plant. The nodulizer is a cylinder 8 ft 10 in. in diam by 18 ft long set on a slope of 1/2 in. per ft, and rotated at about 10 rpm. It is driven by a 50 hp wound rotor motor drawing about 9 kw. The inside of the shell is cleaned by a continuously operating scraper which draws 0.1 kw. The dry raw material is fed to the nodulizer where, being sprayed with water, it rolls into small spheres about 90 pct being between 1/2 and 1 in. in diam and containing about 15 pct water. The nodules fall on the traveling grate where the hot gas from the kiln is pulled down through the

Jan 1, 1951

By R. A. Kinzie

THE major operating costs in a cement plant are labor, power, and fuel. The opportunities and methods of savings in labor and power parallel other industries. Because our industry's use of fuel is large and its method of use is unique, the devices adapted for saving fuel are of interest. In normal practice the raw material in the form of a dry powder or a mud is fed to a rotating inclined cylinder where it is dried, calcined, and clinkered. In a Lepol kiln the raw material is rolled up into little balls with water in the nodulizer, fed to a traveling grate on which it is dried and partially calcined and tben to a short kiln where the process is finished. The more usual methods of saving heat have been the use of long kilns with chains in wet process plants and the use of waste heat boilers in dry plants (fig. 1). At the Santa Cruz plant we have used a Lepol system kiln and achieved a fuel 'economy of 4.7 gal per bbl of clinker or about 704,-000 Btu per bbl. This can be compared with our old kilns using the same fuel and raw material which consume 7.8 gal per bbl or 1,130,000 Btu per bbl. These are gross Btu and not the net figures usually used in reports of foreign companies. Our average consumption for 1948 was 708,000 Btu per bbl of Lepol clinker, based on cement sold, and oil purchased. The overall fuel consumption for 1948 was 6.61 gal per bbl. The Lepol system consists of a nodulizer, a grate, and a kiln. There is the usual accessory equipment which is similar to that used in other cement plants. The following description covers the equipment in operation at our plant. The nodulizer is a cylinder 8 ft 10 in. in diam by 18 ft long set on a slope of 1/2 in. per ft, and rotated at about 10 rpm. It is driven by a 50 hp wound rotor motor drawing about 9 kw. The inside of the shell is cleaned by a continuously operating scraper which draws 0.1 kw. The dry raw material is fed to the nodulizer where, being sprayed with water, it rolls into small spheres about 90 pct being between 1/2 and 1 in. in diam and containing about 15 pct water. The nodules fall on the traveling grate where the hot gas from the kiln is pulled down through the

Jan 1, 1951

By Gerhard Derge

THE orientation relationships resulting from allotropic transforma-tions and the formation of segregate structures in metals and alloys have been the subject of the eight earlier papers in this series1. A brief summary of orientation studies has also been given by Sachs2. A survey of these papers discloses that the factors that determine the orientation relationship of a precipitated phase to its parent solid solution, as Well as the outward form and appearance of the new phase, are not completely understood. It is now evident that crystallographically analogous systems, as a rule, exhibit the same type of Widmanstätten figure and orientation relations, so that useful information is not to be expected from examination of a new alloy involving lattice combinations of which the orientation relationships are already known. Therefore, the determina-tion of the relations existing between lattice types that have not already been studied seems to be the most promising mode of attack upon the problem; both of the systems reported in this paper represent new com-binations of lattice types.

Jan 1, 1937

By C. Graeme-Barber, R. L. Bell, T. G. Langdon

An analysis is made of the formulas and ,methods used to estimate the contribution of grain boundary sliding to the overall strain of a polycrystal. The errors involved in the approximations and/or ,mistakes in earlier work are assessed quantitatively so as to make possible the critical use of previously published data. SINCE it has been found that, under conditions of very slow creep, the strain due to grain boundary sliding (?gb) may contribute as much as 80 pct of the total creep strain,1,2 it is obviously important to have reliable methods for estimating this grain boundary strain. In two recent papers Stevens3,4 has drawn attention to the pitfalls encountered in assessing ?gb. He criticizes 1) the assumptions made in the derivation of some of the formulas for ?gb, and 2) the indiscriminate averaging procedures used for obtaining the quantities substituted in these formulas. These and further criticisms of earlier work are mostly valid. Unfortunately the only formulas and procedures recommended are either impossible or very difficult to apply in practice. Furthermore no attempt is made to assess the errors involved by the earlier approximations or mistakes, and so it is not possible to make critical use of any of these early dab. The present article attempts to improve on these shortcomings by reference to empirical verification of easily applied formulas whose theoretical derivations involve some otherwise unjustifiable assumptions, and by a quantitative assessment of the errors in previous work. DEFINITIONS First it is necessary to define the terms and symbols to be used. The choice of symbols preferred here is a logical combination and extension of the v introduced by McLean5 and the u by Brunner and rant.' In Fig. 1 the two grains X and Y are displaced by the sliding vector AC. u is the component of sliding resolved along the stress axis, v is that measured perpendicular both to the stress axis and to the specimen surface, and w is that measured perpendicular to the stress axis but in the plane of the surface. Two angles define the orientation of the grain boundary: 8, between the stress axis and the surface trace of the boundary, and +, the internal angle on a longitudinal section cut perpendicular to the surface. In computing the strain resulting from the boundary displacement at all the in- dividual boundaries in a polycrystal the components u, v, or w are sometimes averaged along a longitudinal line (i.e., parallel to the stress axis), sometimes along a transverse line, and sometimes at randomly chosen boundaries. Averages obtained in these three ways are given subscripts 1, t, and r, respectively. Stevens rightly calls attention to the possibility of non-equiaxed grain shapes either at the start or at the end of deformation. In this article all values of numbers of grains per unit length will refer to measurements made before deformation. The subscripts 1 and t will be used for the number of grains per unit length obtained along longitudinal and transverse lines, r for that obtained by averaging along a number of randomly directed lines. FORMULAS FOR ?gb ?gt, as a Function of u. An obvious truth is that cgb can, in principle, be obtained by summation of all the v components at the boundaries intersected by a longitudinal line of known length I, viz.: where nl is the number of grains per unit length, parallel to the stress axis, in the unstrained specimen. There are assumptions in the analytic derivation of Eq. [I] due to Brunner and rant' but ~achinger' arrived at Eq. [la] by a rigorous method. Unfortunately the experimental procedure required by Eq. [ la] proves very difficult as boundary migration tends to obscure the points at which the longitudinal line meets the grain boundary and the errors on such measurements tend to be large, see Fig. 2. For example, on a specimen of Magnox AL 80 at a creep strain of 9.7 pct, 300 measurements of u obtained from the points of intersection of a longitudinal line with the grain boundaries gave ul = 8.95 ± 3.58 pm, or an error of ±40 pct, at the 95 pct confidence limit. These large errors due to migration may be avoided by measuring u from the separation of the segments

Jan 1, 1968

By Albert J. Phillips

As early as 1824, Haidinger' described crystals of native copper that were, according to Dana,2 " probably twinned parallel to the octahedral plane and normal to this axis." In 1837, Rose3 very clearly demonstrated that native copper crystals were commonly twinned on the octahedral plane. Lasaulx,4 in 1882, described polysynthetic octahedral twins and stated that enclosed twinning lamellae were observed. Even on crystals formed artificially by electrolysis, twinning was observed as early as 1886, by Brown.5 Many other descriptions of twinning in native copper and in gold and silver are to be found in the literature, and in every case with which we are acquainted the twinning is conformable to the spinel law; i. e., the octahedral plane is both twinning and composition plane. Metallurgists have long been familiar with the straight-sided bars or bands that commonly occur within the irregularly outlined grains of metallic crystalline aggregates. They are certainly found in nearly all metals of the face-centered cubic type after cold working and annealing. If a specimen showing these bands is rotated, keeping the angle of incidence of the illuminating beam constant, they usually exchange color contrast periodically with their respective matrix crystals. Also slip lines, when produced in these specimens, nearly always show a change in direction upon passing through the bands, giving rise to the "stairway" effect often illustrated in metallurgical textbooks. Apparently the only quantitative observations on bands of this sort were made by Osmond and Cartaud6 on austenitic steel. They selected,

The Institute maintains a dual relationship with students (1) an individual relationship with a Student Associate, and (2) a relationship with local organizations of students, known as Affiliated Student Societies or Student Chapters 1 The conditions of Student Associate¬ship are set forth in Section 9, Article I, of the Bylaws of the Institute (see page 74 and following pages) During 1934, sundry amendments were made for the purpose of improving the student relationship Post-graduate students are now eligible, and associateship can be maintained, with the payment of the regular dues of $2 per year, for 18 months following graduation in June With his regular dues, each Student Associate is entitled to receive during the year his choice of MINING AND METALLURGY, METALS TECHNOLOGY, MINING TECHNOLOGY, PETROLEUM TECHNOLOGY, or COAL TECHNOLOGY, and on payment of an additional fifty cents he can have both MINING AND METALLURGY and any one of the others He is accorded the privilege of getting special publications such as "The Porphyry Coppers" and "Elements of the Petroleum Industry" at the reduced prices applicable to Members, he has the privileges of the Engineering Societies Personnel Service and the Engineering Societies Library, and he is not only invited but urged to attend all meet¬ings of the Institute, its Divisions and its Local Sections The Institute wants to extend the hand of professional fellowship to students following mineral industries curricula

Jan 1, 1952

By Joseph C. Mead, Alan Stanley

The MacIntyre Development of the National Lead Co. is located at Tahawus, N. Y. The operations involve the mining and concentrating of a titaniferous iron ore to produce an ilmenite concentrate and a magnetite concentrate. Construction of the MacIntyre plant was commenced during the summer of 1941,when world conditions threatened to cut off the supply of Indian ilmenite. An open pit mining operation was developed and the crushing and milling equipment put in operation in July 1942. A general description of the operation was given in the Adirondack Issue of Mining and Metallurgy for November 1943. The metallurgy of the mill operation was described by Mr. Frank R. Milliken,* Plant Manager, National Lead Company, MacIntyre Development, and presented at the AIME New York Meeting, February 1948. The magnetite concentrate produced in the milling operation was too fine (minus 20 mesh) to be used directly in iron blast furnace operation, and most of the magnetite had to be stockpiled in 1942 and 1943. In 1943, the Defense Plant Corp. built a Greenawalt sintering plant at Tahawus, N. Y., to put the magnetite concentrate in a more suitable form for use in the iron blast furnace. The Greenawalt sintering plant consists of three 10 by 25 ft sintering pans designed to produce 1800 gross tons of sinter per 24 hr. The vacuum to each pan is produced by two Greenawalt fans in series, pulling approximately 30,000 cu ft of air per minute at 50 in. water gauge vacuum. The plant started operation in August 1944. The present plant production averages 25 tons per operating pan hour (approximately 224 lb per operating hour per square foot of grate area) of plus 1 in. sinter. Raw feed to the plant consists of 61 pct magnetite, 4 pct anthracite coal culm, and 35 pct minus 1 in. return fines which are conveyed to a pug mill where the materials are mixed thoroughly and water added to give the mixture 5.5 to 6 pct moisture. The mixed prepared feed is conveyed to two 4 by 10 ft vibrating screens where the minus 1 in. plus 5/8 in. return fines are screened out and discharged into a surge bin for use as a hearth layer. The minus 5/8 in. prepared feed is discharged into another surge bin for use as prepared feed. A charge car, electrically operated, having a capacity of one charge of prepared feed and several charges of hearth layer, lays a thin layer of plus 5/8 in. return fines and 9½ in. depth of prepared feed into the pans. A fluffing roll and a vibrator on the car fluffs and spreads the prepared feed into the pans. An ignition car, electrically operated, ignites the top of the bed with a 30 sec flash burn. The 9½ in. bed sin-ters in approximately 13 min. Dumping the pan, and recharging and igniting the bed requires 2 min. To improve the quality of the ilmenite concentrate produced in the mill and to reduce the amount of titanium dioxide lost in the mill tailings and in the magnetite product, extensive research work and pilot plant operations have been done on grinding the crude ore to minus 65 mesh size (rather than to minus 20 mesh) and concentrating it by a combination of magnetic separation (for magnetite recovery) and flotation (for ilmenite re-covery). These tests have proved successful in increasing ilmenite re-covery and grade. With the development of the ilmenite flotation process to a stage where a full scale flotation plant was in the design stage, the problem arose of handling the 65 mesh magnetite concentrate that would be produced. In order to study and solve the problems of handling and sintering the 65 mesh magnetite in the sinter plant, a pilot sinter plant was secured from John E. Greenawalt. The effect of using 65 mesh magnetite in the sintering operations was then studied on the 2.4 sq ft test pan, operating under conditions as similar to the large plant as could be set up in the laboratory. A series of tests were run in the test pan on present sinter plant feed that had been mixed in the plant pug mill. An average production and an average quality of sinter produced in this series

Jan 1, 1950

By James Douglas

I had the good fortune to visit the Stockholm Exposition just before its close in October last, and to get a glimpse of the methods used in Sweden in making the wonderful steel and iron for which its furnaces are so famous. My time and opportunities for observation were limited, but some points which I noted may be worth bringing to the notice of the Institute. The Exposition itself was confined to the natural and artificial products of Scanclinavia, and therefore iron and steel held a very prominent place in it. There was a complete collection of the rocks and ores of the Peninsula made by the Geological Survey; and every iron-mine of note exhibited a glass model of its workings, as well as classified specimens, accompaniecl by thorough analyses of the ores. Another feature of interest was the display of models of the old mining-machinery, in the invention and introduction of which Sweden led the way, and of the old and new surveying-instruments and compasses devised for the exploration of the Swedish iron-ore bodies, all of which are more or less magnetic. The magnetometric collection and exhibit of methods of operation made by Prof. Nordestrijm were supremely instructive. The larger metallurgical works, such as those of the Kopparberg and Sandvik companies, exhibited their wares in separate pavilions, in which crude and manufactured objects were arranged most eflectively and tastefully; while the smaller companies erected in the Industrial Arts Building trophies, every one of which was an object of beauty. One was struck on all sides by the fine asthetic feeling exhibited in the ingenious installation of materials and objects not easily lending themselves to artistic treatment. Hammers, picks and drill-steel were grouped into mural designs which it was a delight to look at.

Jan 1, 1899

By W. T. Burns

Attempts were made in 1908, at the Great Falls Works, to produce ingots direct from the Butte precipitate by smelting the material in a reverberatory refining furnace. The ingots produced in this manner averaged 99.4 per cent. of copper and 0.40 per cent. of arsenic and antimony. The copper content being considered too low, it was decided to cast the copper into anodes and to treat the anodes in the electrolytic plant. No. 1 Furnace, in which the precipitate was treated, was a regular cathode refining furnace previously employed in making wire bar, cake, and ingot from electrolytic cathodes. The hearth of the furnace was 24 by 12 ft., having a capacity of 100,000 lb. of cathodes. The furnace was coal fired, and the copper was dipped by means of trolley ladles. The average composition of the furnace charges was as follows: Per Cent. Peer Cent. Copper. Precipitate,..........7.5.3 40 to 80 Purification cathodes,.....1.9 92 Refinery slag (oxide slag),.. 10.1 50 to 60 Electrolytic cathodes,... 2.1 99.9 Precipitate anode scrap,.... 3.1 99.0 Scrap copper,.........7.5 99.2 100.0 The slag from this furnace amounted to 46 per cent. of the total amount charged and was of the following average composition: Per Cent. Cu..............16.86 SiO2.............34.7 FeO.............18.8 A12O3.............13.0 CaO.............9.4 MgO.............2.7 S............... 0.47 As..............0.11 Sb...............0.006 Ag, oz per ton.....0.18

Jan 1, 1914

The Institute maintains a dual relationship with students: (1) an indi¬vidual relationship with a Student Associate; and (2) a relationship with local organizations of students, known as Affiliated Student Societies or Stu¬dent Chapters. 1. The conditions of Student Associateship are set forth in Section 9, Article I, of the Bylaws of the Institute (see page 57 and following pages). During 1934, sundry amendments were made for the purpose of improving the student relationship. Post-graduate students are now eligible; and associateship can be maintained, with the payment of the regular dues of $2 per year, for 18 months following graduation in June. With his regular dues, each Student Associate is entitled to receive during the year his choice of Mining and Metallurgy, Metals Technology, Mining Technology, Petroleum Technology, or two "classes" of Technical Publications; and on payment of an additional fifty cents he can have both Mining and Metallurgy and any one of the others. He is accorded the privilege of getting special publications such as "The Porphyry Coppers" and "Ore Deposits of the Western States" at the reduced prices applicable to Members; he has the privileges of the Engineering Societies Employment Service and the Engineering Societies Library; and he is not only invited but urged to attend all meetings of the Institute, its Divisions and its Local Sections. The Institute wants to extend the hand of professional fellowship to students following mineral industries curricula.

Jan 1, 1938

GOVERNMENT ESTABLISHES DIVISION OF ENGINEERING Government supervision of employment for technical men has been inaugurated by the United States Employment Service, through the establishment of a Division of Engineering, with A. H. Krom, of Chicago, formerly Secretary of the American Association of Engineers, as Director. War demands on the engineering profession have already caused a serious shortage of men with mechanical designing experience and those with practical experience in chemical engineering. At present the professional organizing mediums reach less than 20 per cent. of the estimated 300,000 technical men in the country. This is not a satisfactory arrangement for war times. All the technical men of the country must be reached and, in addition, all men with technical experience must be carefully registered so that they will be immediately available. The advantages of such a governmental registering and systematizing of employment will be apparent at once, to the engineer. Considering that this is principally an engineer's war, the importance of Federal direction of distribution and conservation of the technical service of the country is apparent. The Service will he started through the office of the Director of Engineering, 29 S. LaSalle St., Chicago. All technical men desiring to register for emergency Government work or permanent advancement in positions meeting their qualifications, are urged to volunteer at once for registration, classification and employment.

Jan 8, 1918