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By David Turnbull

STAFF: Editor, Gerhard Derge Carnegie Institute of Technology Schenley Park Pittsburgh 13, Pa. Editorial Assistant, M. A. Redmerski Production Editor, Otto T. Johnson THE METALLURGICAL SOCIETY: J. S. Smart, Jr., President; C. C. Long, Past-President; K. L. Fetters, Vice President; T. D. Jones, Treasurer; R. W, Shearman, Secretary. PUBLICATIONS COMMITTEE OF THE METALLURGICAL SOCIETY: C. L. McCabe, Chairman; H. L. Bishop, K. L. Fetters, J. J. Harwood, W. A. Krivsky, F. C. Langenberg, R. E. Lund, W. O. Philbrook, L. L. Seigle, R. L. Smith, and F. L. Vogel. Review and selection of monuscripts is under the supervision of the following Publications Committees: Extractive Metallurgy Division: C. L. McCabe, Chairman; R. E. Lund, Vice-Chairman; D. H. Baker, Jr., W. A. Krivsky, R. A. Lewis, Paul Queneau, A. S. Russell, R. E. Shinkoskey, W, W. Stephens, and M. E. Wadsworth. Institute of Metals Division: L. L. Seigle, Chairman, Paul A. Beck, I. I. Bessen, J. 0. Better-ton, Jr., J. B. Clark, R. S. Davis, A. E. Dwight, R. W. Fountain, R. B. Gordon, C. D. Graham, Jr., R. W. Guard, J. C. Gurland, E. L. Harmon, J. J. Heger, A. A. Hendricksan, M. Herman, J. N. Hobstetter, H. H. Johnson, Jr., R. R. Nash, T- N. Rhodin, R. H. Richman, W. Ros-toker, P. G. Shewmon, C. W. Spencer, L.SIifkin, J. K. Stanley, C. D. Starr, and H. C. Stumpf. Iron and Steel Division: H. L. Bishop, Chairman; R. E. Boni, F. C. Langenberg, J. B. Wagstaff, and T. V. Wainwright. Published bimonthly by the American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc., 29 West 39th Street, New York 18, N. Y. Telephone: PEnnsylvania 6-9220. Subscription $20 per year for non-AIME members in United States and North, South, and Central America; $25, foreign; $5 for AIME members. Single copies, $4.00, single copies foreign, $5.00. The AIME is not responsible for any statement made or opinion expressed in its publications . . . Copyright 1961 by the American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc. . . . Registered cable address, AIME New York .. . Indexed in Engineering Index, Industrial Arts Index, and Chemical Abstracts . . . Second class postage paid at New York, N. Y., and Ann Arbor, Mich. Volume 221, Number 3.

Jan 1, 1962

By G. E. Frantti

UNDER the auspices of the Geophysical Committee of Michigan College of Mining and Technology, an investigation was made in Michigan's Upper Peninsula to obtain geophysical data" related to the regional subsurface geology in the area covered by Paleozoic sediments. The area surveyed includes that portion of the Upper Peninsula which lies between R18W to R26W and T41N and T49N, covering approximately 1300 square miles. On the index map, Fig. 1, it is represented by the cross-hatched zone west of Munising. Four of the five sites of detailed investigation are indicated by the letters A, B, C, and D. A detailed gravity and magnetic survey had previously been conducted by J. G. Wilsonz near Perkins, 8 miles north of Rapid River, on a local anomalous area. Results of his work, which showed a large positive magnetic anomaly associated with a gravity anomaly, aroused interest in the possible economic significance of the formations underlying the Paleozoic sediments in this part of the Upper Peninsula. Early in the 1900's the Michigan Geological Survey, as well as many private companies, had done a considerable amount of dip needle work near the southwest corner of the area discussed in this paper. Most of the information available to the writer was obtained from indicated magnetic anomalies on the geological map of the northern peninsula of Michigan. Results of the geophysical activities of mining companies in the vicinity of the Marquette range and Gwinn district were unavailable to the author. Physiography and Geography: The region under consideration has low to moderate relief. About half the area is comprised of swampy lowlands, and because of the swamps and forests much of the land is almost inaccessible. The major drainage system is dendritic, with streams flowing into Lake Michigan on the south and Lake Superior on the north. The general geology, shown in Fig. 2, indicates an overlay of Paleozoic sediments on pre-Cambrian formations along a line running approximately south from Marquette (not shown on the geological map). Actual contact between pre-Cambrian and Paleozoic sediments is not known because most of the area is covered with glacial till, and outcrops are very scarce. Exposures of the Paleozoic sediments show that these beds in the northern areas dip gently under Lake Superior and that in the southern areas they 'dip gently to the southeast. Outcroppings of the pre-Cambrian formations occur primarily to the west of the surveyed area except in the northwest corner where the Laurentian series outcrop as far east as the Gwinn district and also in T46N, R24W. Instrumentation: Gravity measurements were made with the Worden portable gravity meter. Since this was chiefly a reconnaissance regional survey, both the large and small dials were used. The instrument used had a constant of 0.0035 milligals per scale division, a working range of about 25 milligals.

Jan 1, 1957

By Francis A. Thomson

DO the curricula of our mineral technology schools prepare their graduates to meet properly the full range of their responsibilities in after life? An unequivocal "no" could be returned to this question, because training and experience in professional work are quite as important as adequate college preparation. Furthermore, a had curriculum with a splendid corps of men doing the teaching and a competent body of students doing the learning will produce a better result than an ideal curriculum in the hands of unqualified teachers and poorly prepared students.

Jan 1, 1937

By J. T. Eash, E. M. Wise

Platinum and palladium are the most generally useful, most ductile and least rare members of the platinum family. They have many important applications in the pure state but for other applications it is frequently desirable to harden them and otherwise modify their properties by alloying small amounts of the other platinum group metals with them. These alloys are frequently required to withstand very drastic forming operations and to possess certain mechanical properties to fulfill specific requirements. For these reasons a knowledge of the tensile properties and annealing characteristics of pure platinum and palladium as well as their more useful commercial alloys is important to the user and the fabricator. The present work was undertaken to fill this need. Rather brief (5 min.) annealing treatments were employed to render the data of maximum practical value and all tests were conducted upon 0.050-in. dia. wire, initially reduced 50 per cent in area by cold drawing, for the same reason. Conclusions 1. Pure (thermocouple grade) platinum reduced 50 per. cent by cold drawing exhibits the following tensile properties: ultimate tensile strength, 36,000 lb. per sq. in.; proportional limit, 27,000 lb. per sq. in.; elongation, 2.5 per cent in 2 in.; reduction in area, 95 per cent. When fully annealed by treatment at 1100°C. its properties are: ultimate tensile strength, 20,700 lb. per sq. in.; elongation, 30 per cent in 2 in.; reduction in area, 93 per cent. 2. The addition of alloying elements in moderate amounts markedly increases the strength and annealing temperature without much detriment to the ductility. The behavior and properties of variously hardened platinum alloys are considered in some detail. The behavior of a 20 per cent iridium

Jan 1, 1935

By J. T. Eash, E. M. Wise

Platinum and palladium are the most generally useful, most ductile and least rare members of the platinum family. They have many important applications in the pure state but for other applications it is frequently desirable to harden them and otherwise modify their properties by alloying small amounts of the other platinum group metals with them. These alloys are frequently required to withstand very drastic forming operations and to possess certain mechanical properties to fulfill specific requirements. For these reasons a knowledge of the tensile properties and annealing characteristics of pure platinum and palladium as well as their more useful commercial alloys is important to the user and the fabricator. The present work was undertaken to fill this need. Rather brief (5 min.) annealing treatments were employed to render the data of maximum practical value and all tests were conducted upon 0.050-in. dia. wire, initially reduced 50 per cent in area by cold drawing, for the same reason. Conclusions 1. Pure (thermocouple grade) platinum reduced 50 per. cent by cold drawing exhibits the following tensile properties: ultimate tensile strength, 36,000 lb. per sq. in.; proportional limit, 27,000 lb. per sq. in.; elongation, 2.5 per cent in 2 in.; reduction in area, 95 per cent. When fully annealed by treatment at 1100°C. its properties are: ultimate tensile strength, 20,700 lb. per sq. in.; elongation, 30 per cent in 2 in.; reduction in area, 93 per cent. 2. The addition of alloying elements in moderate amounts markedly increases the strength and annealing temperature without much detriment to the ductility. The behavior and properties of variously hardened platinum alloys are considered in some detail. The behavior of a 20 per cent iridium

Jan 1, 1935

By Leslie F. Tedsen, John E. Dorn, Alan E. Flanigan

It is necessary occasionally to use aluminum-alloy sheet where moderately elevated temperatures are encountered. Considerable attention has been directed toward determining the influence of "artificial aging" on the room-temperature properties of the precipitation-hardenable alloys, as testified by numerous company reports and by references I to 4. Investigations on the properties at elevated temperatures are few, however, and have not always covered the range of times and temperatures of greatest interest. The present investigation was instituted to overcome this deficiency. The work was done for the Office of Production Research and Development of the War Production Board, under the supervision of the War Metallurgy Committee, as a part of the "restricted" Project NRC-548. It has been released for publication by the Office of Production Research and Development. AS is well known, the high-strength aluminum alloys achieve their remarkable properties as a result of precipitation-hardening. In production they are subjected to a solution heat-treatment followed by quenching, to retain the supersaturated solid solution. The solution treatment is followed by "aging" (precipitation-hard- ening) either at room temperature or at a suitable elevated temperature. A considerable increase in tensile and compressive yield stresses results from precipitation at room temperature ("natural aging"). Through the elevated-temperature process ("artificial aging") it is possible to obtain values of yield stress considerably higher than those attainable by natural aging. The increase in yield stress is accompanied by a smaller gain in ultimate tensile stress and by a decrease in elongation. During the first stages of artificial aging the yield stress increases steadily until it reaches a maximum value. In this condition the material is said to be "fully aged." Further exposure results in "averaging," attended by a steady decrease in yield stress. In the production of the artificially aged materials, temperatures and times are selected to achieve full aging. The following important characteristics are associated with the process: 1. The higher the temperature, the more rapidly is the fully aged condition attained. :7

Jan 1, 1946

By Leslie F. Tedsen, Alan E. Flanigan, John E. Dorn

It is necessary occasionally to use aluminum-alloy sheet where moderately elevated temperatures are encountered. Considerable attention has been directed toward determining the influence of "artificial aging" on the room-temperature properties of the precipitation-hardenable alloys, as testified by numerous company reports and by references I to 4. Investigations on the properties at elevated temperatures are few, however, and have not always covered the range of times and temperatures of greatest interest. The present investigation was instituted to overcome this deficiency. The work was done for the Office of Production Research and Development of the War Production Board, under the supervision of the War Metallurgy Committee, as a part of the "restricted" Project NRC-548. It has been released for publication by the Office of Production Research and Development. AS is well known, the high-strength aluminum alloys achieve their remarkable properties as a result of precipitation-hardening. In production they are subjected to a solution heat-treatment followed by quenching, to retain the supersaturated solid solution. The solution treatment is followed by "aging" (precipitation-hard- ening) either at room temperature or at a suitable elevated temperature. A considerable increase in tensile and compressive yield stresses results from precipitation at room temperature ("natural aging"). Through the elevated-temperature process ("artificial aging") it is possible to obtain values of yield stress considerably higher than those attainable by natural aging. The increase in yield stress is accompanied by a smaller gain in ultimate tensile stress and by a decrease in elongation. During the first stages of artificial aging the yield stress increases steadily until it reaches a maximum value. In this condition the material is said to be "fully aged." Further exposure results in "averaging," attended by a steady decrease in yield stress. In the production of the artificially aged materials, temperatures and times are selected to achieve full aging. The following important characteristics are associated with the process: 1. The higher the temperature, the more rapidly is the fully aged condition attained. :7

Jan 1, 1946

By J. M. Bugbee

The engineer and the conservationist agree that effective water drive is the desirable reservoir production mechanism. Water drive may result either from the expansion of edge water, the reservoir water bordering an oil pool, or from the artesian flow of edge water from the outcrop. Thus, the extent of the reservoir has an important bearing upon both the rate and the ultimate quantity of water influx to an oil pool. Lens-type reservoirs are generally recognizable, but the complete structure of the more important domal types, having possible limitations from crestal and synclinal faulting, is not well understood. The delineation from cores, electrical logs and exploitation phenomena of the crestal portions of reservoirs is increasingly exact. This paper suggests that inference from these factual pictures, combined with the scattered well and geophysical data of the synclines and with consideration of the dynamics of structural formation, may be applied to solving the complete geologic structure. Since faulting on the domes and in the synclines may effectively seal and thus limit the size of a reservoir and bar additional water influx, consideration of geologic structure and its possible effects is essential to complete analysis and prediction of reservoir performance. Introduction Implicit in reservoir studies is the fact that the oil must be displaced from the reservoir rock by some other fluid, either gas or water, and this understanding yields the terms descriptive of the major reservoir production mechanisms, gas expansion and water drive' Three recent papers1-2-3 make clear the economic and conservation preeminence of Water drive as a production mechanism; in fact, the title of the latest of these is " Production under Effective Water Drive as a Standard for Conservation Practice." There appears to be an assumption at times among analysts that the effectiveness of a water drive is solely dependent on the rate of oil production; that is, if water drive appears to be insufficient or lacking, a lower oil-recovery rate would increase or reveal it. This assumption might result from the fact that the analysis has been wholly developed during the period of production curtailment; that is, since 1929. The writer takes it that the recurrent phrase in De Golyer's paper,3 "some degree of water drive," is related to this assumption. In California, an extraordinary phrase, "inactive water drive," is rather common and the connotation of uncertainty regarding our knowledge of reservoir performance is evident. Wyckoff2 speaks of the type of reservoir and performance as follows: "In general, reservoirs may be any one or a combination of domal, faulted, lenticular, or stratigraphic traps. Insofar as the dynamic performance of such reservoirs is concerned, the particular type merely determines whether regional flow is symmetrical as in a uniformly developed domal or lenticular type, or one-sided as in many stratigraphic or faulted traps." But whether the flow is

Jan 1, 1943

By J. M. Bugbee

The engineer and the conservationist agree that effective water drive is the desirable reservoir production mechanism. Water drive may result either from the expansion of edge water, the reservoir water bordering an oil pool, or from the artesian flow of edge water from the outcrop. Thus, the extent of the reservoir has an important bearing upon both the rate and the ultimate quantity of water influx to an oil pool. Lens-type reservoirs are generally recognizable, but the complete structure of the more important domal types, having possible limitations from crestal and synclinal faulting, is not well understood. The delineation from cores, electrical logs and exploitation phenomena of the crestal portions of reservoirs is increasingly exact. This paper suggests that inference from these factual pictures, combined with the scattered well and geophysical data of the synclines and with consideration of the dynamics of structural formation, may be applied to solving the complete geologic structure. Since faulting on the domes and in the synclines may effectively seal and thus limit the size of a reservoir and bar additional water influx, consideration of geologic structure and its possible effects is essential to complete analysis and prediction of reservoir performance. Introduction Implicit in reservoir studies is the fact that the oil must be displaced from the reservoir rock by some other fluid, either gas or water, and this understanding yields the terms descriptive of the major reservoir production mechanisms, gas expansion and water drive' Three recent papers1-2-3 make clear the economic and conservation preeminence of Water drive as a production mechanism; in fact, the title of the latest of these is " Production under Effective Water Drive as a Standard for Conservation Practice." There appears to be an assumption at times among analysts that the effectiveness of a water drive is solely dependent on the rate of oil production; that is, if water drive appears to be insufficient or lacking, a lower oil-recovery rate would increase or reveal it. This assumption might result from the fact that the analysis has been wholly developed during the period of production curtailment; that is, since 1929. The writer takes it that the recurrent phrase in De Golyer's paper,3 "some degree of water drive," is related to this assumption. In California, an extraordinary phrase, "inactive water drive," is rather common and the connotation of uncertainty regarding our knowledge of reservoir performance is evident. Wyckoff2 speaks of the type of reservoir and performance as follows: "In general, reservoirs may be any one or a combination of domal, faulted, lenticular, or stratigraphic traps. Insofar as the dynamic performance of such reservoirs is concerned, the particular type merely determines whether regional flow is symmetrical as in a uniformly developed domal or lenticular type, or one-sided as in many stratigraphic or faulted traps." But whether the flow is

Jan 1, 1943

By George Branner

THERE is no record of the commercial production of bentonite as such in Arkansas up to the present although fuller's earth has been. mined intermittently in the state1 from 1891 to 1922. Very nearly all of this was obtained from decomposed basaltic dikes.2 Recently three bentonite deposits of close stratigraphical relationship have been identified in the Coastal Plain region of southern Arkansas, which suggests that there may be a considerable quantity of commercial material available. LOCATION AND ACCESSIBILITY The three deposits are located respectively in the SE. ;1/4 SE. ;1/4 sec. 13, T.- 2 S., R. 13 W., Saline County, the SE. ;1/4 SE. 1/4 sec. 18, T. 5 S., R. 16 W., Hot Spring County, and in sec. 22, T. 12 S., R. 19 W., Ouachita County. The Saline County deposit is 14 miles by state highway 167 south of the city limits of Little Rock and 1 mile west by dirt road. This deposit is 12 miles south of Ward switch on the C. R. I. P. Railroad and 11 miles east of Vimy Ridge by dirt road. Vimy Ridge is also on the C. R. I. P. Railroad. The Hot Spring County deposit located in the SE. ¼ SE. ;1/4 sec. 18, T. 5 S., R. 16 W. is about 100 yd. north of Durian switch on the C. R. I. P. Railroad and on state highway No. 9, 5 miles southeast of Malvern. The Ouachita County deposit has not been accurately located but lies in sec. 22, T. 12 S., R. 19 W. It is approximately 2 miles by road from Chidester on the Missouri Pacific Railroad.

Jan 1, 1929

By E. J. KENNEDY

METHODICAL AND EFFECTIVE: thus may be characterized the fall meeting of the Iron and Steel and Institute of Metals Divisions at the Hotel Statler, Buffalo, N. Y., on Oct. 4 and 5. Approximately 200 registered. Interest centered 1111 the technical papers which were keenly followed, with substantial discussion: During the entire week of the National Metal Congress (Oct. 3 to 'i), there were also other sessions of interest' to metallurgists, directed by the America11 Society for Steel Treating, American Welding Society, Production Division of the Society of Automotive Engineers, the Iron arid Steel and Machine Shop Practice Divisions of the American Society of Mechanical En,' the Wire Association and the American Drop Forging Institute. The National Metals Exposition at the 174th Regiment Armory was well attended.

Jan 1, 1932

By D. L. McDanels, J. W. Weeton, R. W. Jech

An investigation was conducted to determine the stress-strain behavior and tensile properties of metallic composites and to relate them to the properties of the base materials. Tungsten fibers in a copper matrix were chosen as the model sys-tem to investigate these properties. Room-temp-atzcre tensile and dynamic -modulus tests were used To meet the demand for improved structural materials, considerable effort is being directed toward the creation of composite materials. One such material under investigation is the fiber-reinforced composite, in which a ductile, relatively weak matrix is reinforced with high-strength fibers. Some work has been done on the reinforcement of metallic matrices with metallic fibers1"5 as well as with ceramic-whisker reinforcement. Summaries of much of this work have been published by Mach-lin7 and Baske~.' Work done at the Lewis Research Center of NASA-" has involved the making and testing of composites composed of a fiber, tungsten, and a matrix, copper, which were insoluble in each other. An equation was presented that showed the relation between the ultimate tensile strength of the composites and the strengths and relative volume percents of the components. This relation was verified experimentally for composites containing fibers extending the full length of the specimen as well as for composites reinforced with short-length or discontinuous fibers. Since the publication of the preliminary results,9'10 additional data have been obtained. This paper presents these data as well as analyses of the stress-strain behavior and the mechanics of deformation of uni-axially oriented, fiber-reinforced metallic composites, in which both components are mutually insoluble. EXPERIMENTAL PROCEDURE Composites were made with high-purity copper as the matrix and 3-, 5-, and 7-mil-diam tungsten wire as the reinforcing fiber. Some specimens were made in which the reinforcing fiber extended completely through the full length of the composite test section. The fibers were placed in ceramic to determine these properties. The composites were reinforced with either continuous or discontinuos tungsten fibers. The tensile properties and stress-strain behavior of composites reinforced with either type of reinforcement were similar, and in both cases the full strength of the fiber was utilized. tubes to insure axial orientation and infiltrated with copper at 2200°F for 1 hr. Composites were also made with short-length (3/8 in. long) 5-mil-diam tungsten fibers as discontinuous reinforcement and infiltrated under the same conditions. The reinforcing fibers in both cases were longitudinally oriented in the direction parallel to the tensile axis. Room-temperature tensile tests were conducted on the composites, stress-strain curves were obtained, and ultimate tensile strength and elongation were measured. Dynamic modulus of elasticity, based upon the resonant frequency induced in the flexural mode of vibration, was also determined for the composites and the components. A more detailed discussion of the experimental procedure employed in this investigation may be found in Ref. 11. RESULTS Room-temperature tensile tests were conducted on 3-, 5-, and 7-mil-diam tungsten wires which had been annealed for 1 hr at 2200°F and show the tensile strength of the wires to be 331,000, 327,000, and 290,000 psi, respectively. Since all the composites were infiltrated under these conditions, the strengths were considered to represent the strength of the fibers in the composites throughout this study. The average tensile strength of the annealed copper used as the matrix in this investigation was 27,800 psi. Results of room-temperature tensile tests on composites reinforced with 3-, 5-, or 7-mil-diam tungsten fibers are plotted as functions of composition in Fig. 1. These data represent previously reported datag,l0 as well as data more recently obtained. The line shown on each curve represents a prediction of tensile strength as a function of composition; the calculation of this line was explained in Refs. 9 and 10. A similar plot is presented in Fig. l(d) for composites reinforced with short-length, discontinuous 5-mil-diam tungsten fibers. Again, both the previously reported and the recent data are presented, and the line shown is identical to that shown for

Jan 1, 1965

By T. T. Read

TWO papers on health and safety were given Thursday afternoon when a joint session of the Health and Safety Committee and the Mining Methods Committee was held. T. T. Read presided and the first paper, on ventilation at Climax, was presented by the author, L. H. Glanville. In the subsequent discussion by Cloyd M. Smith, P. B. Bucky, B. F. Tillson, D. F. Haley, J. L. G. Weysser, and others a number of interesting points not covered by the paper, which appears in full in the January Mining Technology, were brought out. Ventilation troubles in mines so often hinge on the air being too hot and damp that it was interesting to hear of one where it is frequently too cold and too dry.

Jan 1, 1943

By Serge L. Delinois

President Kennedy said that before 1970 this country will send a man to the Moon and get him back on Earth safely. Today, no one doubts that his promise will become reality. He who asks "What, then, is next for us in space?" is no longer considered a dreamer. And one of the very first things he discovers in trying to answer this question is that in whatever does come next, geologists and mining engineers will play a prominent role. This will be true not only in the conquest of the Moon, but also in that of the whole solar system. After 1970, it is very likely that a permanent lunar camp will be established. This beachhead, supplied entirely from Earth, in the beginning, will gradually develop into a research complex where virtually all scientific disciplines are investigated.

Jan 1, 1966

By C. C. Whittier

CIVILIZATION'S PROGRESS, which has multiplied man's comforts, conveniences, a n d happiness, is based upon the extensive employment of natural minerals and sources of energy. Mineral resources are basic factors in modern economic development, machine industry, international trade and world power. A survey of mineral consumption shows that the United States leads the world in the production and consumption of energy materials, of metals, and of the large and diverse array of earth materials that fall in the nonmetallic mineral group. The use of nonrnetallic minerals exceeded both the metals and the fuels in the long period before the industrial age, but it is only in the last two decades that consumption of non- metals has kept pace with and approximated in value the output of metals. Although the data of production in the first half of the last century are meager and fragmentary, the record of the past fifty years-the period of most rapid growth-is available, and reveals an astounding growth.

Jan 1, 1933

By Bunting S. Crocker

PEBBLE grinding at Lake Shore is not a temporary wartime substitute. The tube milling plant, with a 1000 ton per day capacity, grinds a hard siliceous ore to 90 pct - 325 mesh. The plant, prior to using pebbles, was consuming 4.3 lb of 1 1/4-in. grinding balls per ton of ore, which amounted to 785 tons of balls per year. At September 1951 prices, $132.60 per ton, this steel cost amounted to, $104,400 per year, or $0.285 per ton milled. By the Lake Shore method of substituting screened rock for this steel, all of this cost is saved. This is one of the major economies in Lake Shore mill practice. Regardless of the ultimate price of grinding balls, a change, back to steel balls is not considered. The present pebble plant is more flexible than a steel ball plant and equally efficient. For example, if it is desired to change the size of grinding media, the pebble charge in any mill can be changed completely in 4 to 5 days, as against 76 days to change completely a 1 1/4-in. steel ball charge. To change pebble size it is necessary only to change two sets-of screens and clean out the rock feed storage bin. This will take 8 to 10 days as against 3 to 4 months to clean. out the customary supply of grinding balls kept on hand. Also it has not always been ' possible to purchase all desired sizes of balls at any price. In an analysis of savings effected by the use of the pebble mills, the flexibility of the Lake Shore grinding plant should be discussed, as it has a direct bearing on these savings. The plant has always used several units to handle tonnage rather than sending all the tonnage through a single unit. This principle may result in using small diameter mills, but no objection to that is seen. At no time has any advantage been found in cost per ton ground in large diameter mills. Both the capacity and the power of any mill varies as the diameter raised to the 2.6th power. Consequently large or small mills are equally efficient, and a plant should be designed to use as many units-or combination of units as is consistent with reasonable operating practice. Mills under 5 ft diam are harder to reline, etc. To define the case at Lake Shore, .2600 tons per day formerly were milled in seven 7x6-ft ball mills and twelve 5x16-ft (and two 6x16-ft) tube mills.* This gave an excellent test plant. and an extremely efficient-one. In this plant the ratio of ball mills to tube mills was 1: 2. When the much cheaper pebble mills were substituted for the tube mills, this. ratio -was changed to one ball mill to four pebble mills to take the greatest possible advantage of the cheaper operating mill, i.e., the pebble mill. This flexibility without loss in efficiency has been an important item in the cost savings. It is interesting to note that the use of pebbles for fine grinding was. proved first in the laboratory in a 12-in. ball mill. In fact, since 1934 all testing on -.8 mesh material has been done in this 12-in. mill. Scope of the Tests A paper on fine grinding at Lake Shore Mines was published in July 1940.1 This paper covered 7 years of intensive research on fine grinding as well as sizing methods and equipment, plant scale grinding tests on 5x16-ft tube mills with and without .grate discharges-both with 1 1/4-in. and 3/4-in. balls, the use of laboratory mills to evaluate plant changes, and several reports on classifiers and classification. In the following July the addendum report' was added in which the idea of series-circuit grinding was introduced, and the results of running five stages of tube mills and bowl classifiers were shown. Since 1940, the ball milling end of the plant has been altered extensively as a result of tests on the use of 3 1/2-in. rods in 7x6-ft mills and the use of the Tyler repulping screen with from 7 to 14 mesh screens. These tests are, lengthy and may be covered in a separate 'report later. The scope of this report is confined to ore ground by rod milling and ball milling until it passed through an 8 mesh Tyler Ty-rod screen. The -8 mesh screen undersize then was pumped to a primary bowl classifier in open circuit and the sands .from the bowl sent to the primary pebble mills, see Fig: 1. In the pebble mill circuit the ore is ground to 90 pct -325 mesh (24 pct + 28 microns) In studying the flowsheet, attention should be paid to the efficiency of the classification equipment used. The Tyler repulping screen is an efficient machine on the 8 to 10 mesh separation, and the bowl classifier is equally efficient at the 325 mesh separation. Efficient classification is a necessity for series-circuit stage grinding. The ore is hard siliceous porphyry, 60 pct SiO2, 80 pct insoluble. Its grindability at different. meshes has been shown near the top of 'the list in F. C. Bond's grindability tests' Lake Shore is not shown, but an adjacent-mine with identical ore, Wright-Hargreaves, is. Reasons for the-Changeover Since 1936 grinding balls have been rising steadily in price with no sign of stopping. For a mill that used 4.5 to 5.2 lb of grinding balls for every ton of ore ground this rise represented an alarming increase in grinding costs. In many cases the quality of the grinding balls fell off as the scrap steel became more difficult to obtain. The ratio of tube mills to ball mills increased with the use of the Tyler repulping screen in the ball mill circuit. Originally only 3.0 lb of balls per ton were used in the tube mills, and this

Jan 1, 1952

By Joseph S. Malesky

The discovery and development of explosives mark one of the most important findings in the history of civilization. Without explosives our vast economic enterprise concerning the mining of coal, copper, iron, aluminum, and various other ores could not function. Explosives are used in all kinds of construction works, in the razing of old buildings, blasting of trenches, driving of tunnels, and in many other instances common to our everyday life. For these reasons explosives are rightfully referred to as the forerunner of progress. An explosive may be defined as a substance (usually a mixture) that, when flame or shock is applied, yields readily to rapid combustion or oxidation, accompanied by the formation of such relatively large quantities of gases as to produce much violence and pressure which, in turn, react against their surroundings and cause what is termed an explosion. By their very nature the action of explosives is destructive and disruptive of adjacent materials. Decomposition of explosives can occur through deflagration, which is rapid burning or combustion, as in the case of black powder, or through detonation, which is an almost instantaneous disruption, as in the case of dynamites and blasting agents. HISTORY OF BLASTING WITH EXPLOSIVES At one time workmen obtained stone blocks for building by grooving the rock with crude picks, driving wooden wedges into niches in the rock, and pouring water on the wedges; the swelling of the wood forced out the blocks. As late as the 17th century, fires were placed against the face of rock to crack it, and water was sometimes dashed on the heated rock to shatter it by sudden cooling. The progress of our country is synonymous with advancement of the improved manufacture and extended use of explosives. Coal had been

Jan 1, 1981

By Craig S. Hartley

Expressions are obtained for the energy changes associated with the reaction of (a& (111) slip dislocations on intersecting (110)planes in anisotropic bcc metals. An energy criterion for assessing the likelihood of dissociation of the products of such reactions is also presented. It is found that the "burrier reactions" which form a(100) dislocations at the intersection of two active {110) slip planes are more energetically favorable in metals which exhibit a high value of Zener's anisotropy factor, A, than those which have a low value. The results are presented in a form which permits the stacking fault energy to be obtained from a measurement of the separation between par-tials in a dissociated configuration. However, until accurate calculations or measurements of the stacking fault energies involved are available, it is not possible to assess the physical importance of dissociated dislocations. In a recent paper,' the energy changes associated with several types of reactions between two slip dislocations, (a/2)(111){110), in bcc structures were calculated.* Isotropic elasticity and the approxima- tion v = -3- were employed. The purpose of this work is to present calculations of the energy changes for many of the same reactions using anisotropic elasticity. The problem of dissociation of a(100) and a(110) dislocations is also considered, and maximum fault energies for which dissociation will be energetically favorable are calculated for several bcc metals. Two general types of reactions are considered; those for which the reactant (a/2)(111) dislocations have long-range attractive forces and those for which the reverse is true. An example of the former is: (a/2)[lll] + (a/2)[lll]-a[l00] while the latter are typified by: (a/2)[lll] + (a/2)[111] -a[011] Only reactants lying in different slip planes are considered; therefore, the products must lie along (111) or (100) directions, which are the intersection of two {llO} planes. It will be assumed that the reactants and products are infinitely long parallel dislocations, since in this case the energy change associated with the reactions is a maximum.' THEORY The self-energy per unit length of a straight mixed dislocation in an anisotropic medium can be written? where b is the Burgers vector, K is an appropriate combination of the single-crystal elastic constants, and R and ro are, respectively, outer and inner cut-off radii of the elastic solution. The energy given by Eq. [I] does not account for any variation of the core energy with orientation. This could be manifested by an orientation dependence of the core radius or, equivalently, the Peierls width, of the dislocation. However, the energy contribution due to this source is expected to be small, and current models of the dislocation core are not sufficiently accurate to justify such a refinement. It has already been shown that for the isotropic case the energy contributions due to nonzero tractions across the cores of the reactants and products exactly cancel one another in the reaction.' Accordingly, it will be assumed that this contribution to the total energy change in the anisotropic case is small. In the subsequent discussion it is also assumed that the core radii of the reactant and product dislocation are the same and that, where stacking faults are formed, the faulted region is bounded by the centers of the partials. Consequently only changes in elastic energy due to the reactions will be considered. When the dislocation is parallel to either the (111) or the (100) directions, K may be written:375 K = (Ke sin2 a + Ks cos2 a) [2] where K, and Ks are the combination of elastic constants corresponding to an edge and screw dislocation lying along the same direction as the mixed dislocation, and a is the angle between the direction tangent to the dislocation line and the Burgers vector. Eq. [2] should not be confused with the isotropic approximation to the variation in energy with line Orientation.6 It should be noted that the essentially isotropic expression for K is a result of the characteristic symmetry of the (111) and (100) directions and is not, in general, valid for other dislocation directions in anisotropic cubic metals. The energy* change for a reaction in which the re- actant and product dislocations are parallel perfect dislocations can be written: where Ep and E, refer to the self-energies of the products and reactants, respectively. For dislocations parallel to (100) and (111) directions, Eq. [3] becomes:

Jan 1, 1969

By J. D. Cooner

Since my working life of 32 yr has been spent in and about the anthracite mines of the Hudson Coal Co., and the previous 4 yr in a college school of mines, I can write best about the safety program of a coal mining company. However, most of the suggestions, statements and practices mentioned herein are applicable to the members of a safety organization and program of almost any industry. It is realized that industrial officials actually interested in real safety work are fully acquainted with the requirements of a practical safety program. Therefore, for such persons there may be nothing new in this paper. The Hudson Coal Co. of Scranton, Pa., employs 7000 men and produces 5,000,000 tons of anthracite annually at nine collieries scattered for a distance of 40 miles throughout the Lackawanna and Wyoming valleys of northeastern Pennsylvania. For the past 17 yr of the above mentioned 32, I have been engaged in safety work as a safety inspector, assistant mine superintendent, and at present the safety engineer. I have also had the privilege of visiting coal and metal mines in other parts of the United States and Canada. We Americans are the most careless people in the world. If any one doubts this statement why are 100,000 of our people killed accidentally annually? Or why during the almost four years we were engaged in World War II were more of our people killed accidentally at home than were killed in our army, navy, marine corps, coast guard, and other services during the same period? We are careless everywhere— in our homes, on the highway, at work and at play. The purpose of this paper is to outline the requisites of a safety department and its program to stop the accidents occurring to employees at work in mines or industrial plants. The first requisite for a safety program is that the management must be convinced of the need and value of a real safety program. By "management" is meant each department head from the president down. Otherwise a good safety department with a good safety program will not succeed because it will not have the proper personnel and equipment to work with, its rules and regulations will not be enforced, and the members of the safety department will be belittled in the eyes of most of the workmen and supervisors. Next, a safety engineer and his inspectors should have worked in the production end of the mines as workmen and also in an official capacity. They are then in a position to have practical and first hand knowledge of the accident hazards of the industry, how to prevent them, and in general the problems of both the workmen and officials. Some men are appointed as safety inspectors when they are physically unable to carry on as mine officials. Such men may know the safety end of the industry and even be safety-conscious, but if they are physically unable to be mine officials they are also physically unable to be safety inspectors, as a safety inspector in our mines must walk from 2 to 4 miles on each daily inspection and visit each working

Jan 1, 1949

By M. Bevis, A. F. Acton, P. C. Rowlands

Defor~nation twinning and transformation twinning modes most likely to be operative in Fe-Ni and Fe-Ni-C martensites have been determined using a new theory of the crystallography of deformation t~inning.~ This analysis shows that potentially important conventional and nonconventional twinning modes1 have been omitted in previous analyses. Discussion is given on the relevance of the predicted twinning modes to the lattice invariant shear associated with the martensite transformation in steels and to anomalous deformation twinning in Fe-Ni-C martensites. THE two most important criteria which appear to govern operative twinning modes in metallic structures1 are that the magnitude of the twinning shear should be small and that the twinning shear should restore the lattice or a multiple lattice in a twin orientation. The latter criterion ensures that the shuffle mechanism required to restore the structure in a twin orientation is simple. These criteria have been adhered to in the prediction of twinning modes2"6 in bcc and bct single-lattice structures with axial ratios in the range y = 1 to 1.09 as, for example, encountered in martensite occurring in steels. Refs. 2 and 3 in particular consider the martensite transformation in steels and the twinning modes in these cases relate to transformation twinning, and hence the lattice invariant shear associated with the martensite transformation. The list of twinning modes which can be compiled from these sources is incomplete and the ranges of magnitude of shear considered could be unrealistically small, particularly in the case of deformation twinning. The latter consideration is supported by the fact that twinning modes with magnitudes of shear large compared with the smallest shear consistent with a simple shuffle mechanism have been established in, for example, the single-lattice structure mercury7 and the multiple-lattice structure zirconium.&apos; In addition the anomalous deformation twins reported by Ftichrnan4 to occur in a range of Fe-Ni-C martensites still remain unexplained. It is clear that a comprehensive analysis of twinning modes likely to be operative in martensite In steels is required. The results of the application of a new theory of the crystallography of deformation twinningg to these structures are presented in this paper. The theory has been used to determine all shears which restore the lattice or a multiple lattice in a new orientation with magnitude of shear up to a required maximum. The orientation relationships between parent and twinned lattices are not restricted to the classical orientation relationships of reflection in the twin plane or a rotation of 180 deg about the shear direction. PREDICTED TWINNING MODES Twinning modes which restore all or one half of lattice points to their correct twin positions will be referred to as m = 1 and m = 2 modes, respectively. These modes are the most likely to describe operative modes in single lattice structures. The bcc m = 1 and m = 2 modes which have magnitudes of shear s in the range s < 2 and s < 1, respectively, have been given10 and are reproduced here in Tables I and 11. Detailed discussion of the crystallography of these modes and cubic modes in general will be discussed elsewhere (~evis and rocker, to be published). The four twinning elements Kl, &,ql,7)2 as well as the magnitude of shear s are given for each twinning mode, and the twinning modes are given in order of increasing shear. Two twinning modes are given in each row of the tables, the twinning mode Kl, Kz, ql, q2 and the reciprocal twinning mode with elements Kl = K,, Ki = Kl, q: = q2, and 17; = ql. The m = 1 and m = 2 twinning modes which describe twinning shears with small magnitudes of shear and simple shuffle mechanisms in bct crystals with -y = 1 to 1.09 are given in Tables I11 and IV, respectively. On increasing the symmetry of the tetragonal lattice to cubic, that is making y = 1, all modes listed in Tables 111 and IV must reduce to crystallographically equivalent variants of the modes given in Tables I and 11, respectively, or become twinning modes with both shear planes as symmetry planes in the cubic lattice and hence not considered in Tables I and 11. With the exception of this last type of mode only those tetragonal twinning modes which reduce to modes 1.1, 1.2, 2.1, and 2.2 of Tables I and I1 are considered in Tables 111 and IV. For values of y in the range -y = 1 to 1.09 the tetragonal modes and the corresponding cubic twinning modes have approximately the same magnitude of shear. The twinning modes listed in Tables 111 and IV are therefore by the criteria given above the most

Jan 1, 1969