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By Fred Hale

OWING to the large area included in the Yellow Pine mining district, and the-varied nature of its mineral deposits, a detailed geological description of the district could be covered only in an extensive monograph. This paper is intended as a description of the most prominent geologic features only with special reference to those of economic importance. The first mention of the district was in 1903 by J. E. Spurr,1 who briefly describes the structural geology of the Spring Mountain range. In 1906, H. F. Bain2 briefly described the Potosi mine. James J. Hill,3 of the United States Geological Survey, visited the district for a brief period in 1912, the result of which is an excellent reconnaissance report, covering the district in some detail but necessarily with brevity. Since that time, articles covering special features of the district have appeared in the technical press, including some by the writer, and a notable description of the Boss mine, by Adolph Knopf,4 appeared in 1915. Development of the district during the past few years has progressed so rapidly and with so many notable discoveries, particularly with reference to the rare metals, that a further description at this time may prove of interest. The writer's acquaintance with the district is based on 7 years' continuous residence in the vicinity, beginning with the spring of 1910.

Jan 2, 1918

By Pierre Hines

THESE notes are based on observations made while on a recent trip through the West, for the purpose of studying the practical operation of the ball-mill. The writer takes this opportunity to express his thanks for courtesies extended at the many plants visited as well as for the valuable data received. While there are several types of ball-mill on the market, particular attention will here be given to the diaphragm type, as the open-trunnion type, especially the conical mill, has been thoroughly discussed in the Transactions. There is a prevailing impression that the ball-mill is a recent development; however, ball-mills were used extensively in Montana and other western states for crushing ores for concentration as far back as 1898. Its present prominence is due in part to its recent successful application by one of the large copper companies. Without any reference to dry grinding, the first successful ball-mill for wet crushing, which is still in operation, was built 10 years ago.1 This mill, designed by Erminio Ferraris for crushing Sardinian ores for concentration, is of more than passing interest. It embodies the peripheral discharge with grates, large forged-steel balls, and the principal features of the modern ball-mill. The results approach present-clay practice, the chief differences being that the mechanical construction has been improved in the modern types.

Jan 2, 1918

A. Bement, Chicago,Ill. (communication to the Secretary*):— Formerly it was the general practice of engineers to designate coal that is free from moisture and ash as " combustible," notwithstandirig that it contains oxygen and nitrogen. The origin of this practice was more particularly due to the requirements in connection with boiler-testing, which demanded a consideration of that portion of the fuel which took part in the combuition-process because results based on a unit of either moist or dry coal were not comparable, since both moisture and ash were recognized as variable quantities. Thus, a pound of " combustible " became a standard of value, and was treated as a constant before employing measurements of heating-power and calculating therefrom the percentage of efficiency. The recognition of this term " combustible " was an advance to be credited to the engineer rather than to the chemist, because the latter, not having to do with the interpretation of analyses in practice outside the laboratory, usually saw no reason for reporting results in terms other than those of the moist-coal composition. Some years ago I needed a table of fuel-composition in terms of moist, dry, moisture-free and ash-free coal, and of the combustible components. This table required the use of the word combustible in its proper sense, for the purpose of designating carbon, hydrogen, and sulphur, instead of including these three elements with oxygen and nitrogen, to which aggregate the term combustible was formerly applied. To make such a tabulation involved either the use of the inconvenient and cumbersome term, "ash- and moisture-free coal," or of some other representative term, and for this purpose I adopted the expression pure coal, which is short, simple, convenient, and technically correct. It is also harmonious, because it agrees

Jan 1, 1909

LIST OF MEMBERS AND ASSOCIATES ARRANGED ACCORDING TO STATES AND TOWNS. ALABAMA. Aldrich, Aldrich, W. F. Anniston, Noble, A. E Bessemer, Fergusson, V. Bir¬mingham, Aldrich, T. H., Jr, Bowron, C. E, Bowron, J., Davis, F H, Dimmick, F. D., Hillman, Ludwig, C. P., McCarthy, M. E, McCormack, G B., McCrery, Ramsay, E, Shook, A. M. Ensley, McDonald, S., Shook, J. W. Gadsden, Lee, R. H., Jr. Gannts Quarry, Hiller, E Helena, Squire, J. Huntsvalle, Moss Le¬high, Toulmin. Ozmoor, Greenamyer, A. G. Rock Run, Garvin, J M. Selma, Saylor, B. F. A. Sheffield, Miller, D, I. Tuscaloosa, Lodge, J. Woodward, Wood¬ward, A. H. ALASKA Coppermount, Wiswell, H. J. Douglas Island, Macdonald, J Ellamar, Stevens, B. Fairbanks, Hamilton, A L Haines, Le Wald, E A. Jualin, Hoggatt, W. B. Juneau, Denby, Hampton, W. H , Thane, B L , Whipple, J. R. Ketchikan, Bar¬ber, J C , Parker, J. L., Reid, G D Nome, Garfield, C D. Snettwham, Tisdale. Teller, Hirshberg, M. R. Treadwell Caty, Kinzie, Stow, H. P. Valdez, Esterly, G. M, Hazelet.

Jan 1, 1910

By B. W. Vallat

The Newport mine, located at Ironwood, gogebic county, Mich., on the Gogebic iron-range, is owned and operated by the Newport Mining Co., for the mining of iron-ore. I. GEOLOGY. The general geology of the gogebic range has been determined and recorded at different times by well-known geologists,' and their work will be referred to briefly in connection with the local conditions in the mine. The strike of the formation across this property is about 15" north of east. The general dip is 68" to the north. At the base of the formation on the aouth lies the granite. Looking north, at right angles to the strike of the formation, we have the foot-wall of quartz-slates and quartzite about 400 ft. wide; the iron-formation about 800 ft. wide, and the hanging-mall of black slates. The iron-formation is composed of banded jasper and quartzite together with iron oxide and concentrations of iron-ore. In character the ore iu a soft red hematite, with occasional masses of hard blue "steel ore." The formation is crossed in many places by diorite dikes, which cut through at various angles, the larger or main dikes dipping into the foot-wall in a SE. direction at angles varying from 15" to 30°, while numerous small dikes occur which strike through the formation in a vertical plane and at approximately right angles to the main dikes. There are various theories concerning these dikes, especially as to the time of their origin with relation to the ore-deposition. The commonly-accepted theory is that the dikes were there first, but there are some who contend that they were formed

Jan 1, 1912

By Donald O. Rausch, Robert H. Merrill

12.1 -1. Introduction. Problems concerning slopes in soils and rock generally arise in connection with road cuts and open pit mines. The angle at which a slope will safely stand is of major economic importance to both the road designer and the open pit operator. Stable slopes in soils and rock are evaluated through two fundamental approaches, namely, soil mechanics and rock mechanics. The approach selected to make this evaluation depends upon the material in the slope. For the purposes of this chapter, only slopes totally in soil or totally in rock are considered. By definition, soils are unconsolidated accumulations of solid materials produced by mechanical and chemical disintegration of rocks or the accumulation of sediments (28); rock is defined as the hard, compact, natural materials composing the crust of the earth (10). The basic factors affecting slopes in soil or rock are similar, although rock strengths are orders of magnitude greater than soil strengths. In general, the strength of large masses of soil depends upon the texture of the soil, the particle size, cohesion, and resistance to tensile and shear stress; the strength of large masses of rock depends upon the strength of the rock and the defects, such as faults, fractures or joints, that intersect the rock. Further, some of the defects in rock are cemented or uncemented, and may be filled with materials that are strong or weak compared to the rock. In slopes of either soils or rock, the stability is presumed to be a function of the slope height, slope angle, the size of the excavation, and the stresses imposed on the soil or rock by tectonic and/or gravity forces, earthquakes, or other static or dynamic forces. In addition, both soil and rock slopes are affected by static and dynamic water pressures in the pores of soils or permeable rocks or in the defects in the rock behind the slope. Visual observations of slope failures also indicate that both soil and rock can deteriorate with time, and this deterioration may be caused primarily by weathering (27).

Jan 1, 1968

Nov. 4, 1952, AIME, Morenci Sub-section, Longfellow Inn, Morenci, Ariz. Nov. 5, AIME, Chicago Section, Chicago Bar Assn., Chicago. Nov. 8-8, New Mexico Mining Assn. and International Mining Days, joint convention, Alvarado Hotel, El Paso. Nov. 7, AIME, Pittsburgh Section, National Open Hearth Steel Committee, off-the-record meeting, Hotel William Penn, Pittsburgh. Nov. 7-8, Birmingham Technical Meeting of Southeast Section, AIME, Birmingham. Nov. 10-11, Eighth Annual Meeting of The Magnesium Assn., Hotel Biltmore, New York City. Nov. 12, AIME. Connecticut Section, Hartford, Conn. Nov. 18, AIME, Buffalo Section, National Open Hearth Steel Committee, Hotel Statler. Buffalo. Nov. 19, AIME, Connecticut Section, Hartford, Conn. Nov. 19, American Mining Congress Coal Div. Conference, Wm. Penn Hotel, Pittsburgh.

Jan 1, 1952

By Frank C. Roberts

Progress in the facilities for handling mining products has been largely superinduced by the necessities of commercial economy ren dered requisite in order to meet the demand of competition. So rapid has been the depreciation in the value of mineral products, primarily due to the disproportionate increase of output over con sumption, that it may be justly claimed that mining, when considered as a commercial success, depends largely upon the ease and cheap ness by which the products are brought to the surface of the ground. In all methods of performing this operation, wire rope enters as an important factor; and the object of the present sketch will be to explain, as fully as is consistent with the space allotted, the various • adaptations of wire rope employed in placing coal and ores within the reach of our overground systems of transportation. These adaptations will be considered in the following order: I. Hoists. II. Inclined planes. a. Engine planes. b. Gravity planes. c. Aerial planes. III. Haulage. a. Tail-rope system. b. Counter-rope system. c. Endless-rope system. IV. Hoists. The term " hoist" is applied to the system whereby the mine product is elevated from the mine-level to the surface through ver-

Jan 1, 1888

A filled stope is one in which the support for walls and men and, at times, for the back of ore, is furnished by waste rock or sand tailings. The filling may be rock sorted out in the stope or from the walls, develop-ent, or the surface. The orebody is mined in sections, each practically an open or timbered stope, filled wholly or in part before adjacent ground is attacked. As a rule, the filled-stope method is limited to overhand flat-back, stepped-face, or rill stopes. The examples given are Copper Range, Iron Cap, Verde district, Zaruma district, Lucky Tiger, and Silver King Coalition.

Jan 1, 1925

By V. G. Cawagdan, E. M. Sacris

The performance of the grinding circuit, from the initial stages of operation to the present, is discussed. The mill efficiency as measured by the Bond (Bond and Maxson, 1943) grindability data and the operating work index is presented. The objective was to produce a sand cyclone overflow containing not more than 6% 210 µm (+ 65 mesh). This has never been attained, even at low milling rates. Significant improvements in throughput were achieved by instituting equipment changes and process modifications within the grinding circuit. Grind improvements were achieved with enlargement of cyclone spigots, grinding at reduced densities, and decreasing the opening of the ball mill discharge. Additional grinding capacity was realized by converting the concentrate regrinding mill into a secondary ball mill. The previous 20% 210 µm (+ 65 mesh) grind improved to under 15% 210 µm (+ 65 mesh). The latest approach to solving the coarse grind problem is also discussed.

Jan 1, 1985

By George Young

DURING the spring of 1910 I visited a number of open-pit brown-coal mines and underground workings in the vicinity of Halle, Halberstadt, Leipsic, Cologne and Bonn. The notes which I took and the observations which I made at the time have been condensed and make up the principal part of this paper. Certain supplementary information has been taken from several sources which are given in the paper. The mining of brown coal is one of the important industries of Germany. The coal varies in color from dark brown to almost black and is soft like loam. Pieces of wood and strips of bark and, even parts of tree trunks are frequently encountered in the excavation although the coal for the most part consists of a pulverulent, more or less matted mass of small particles of vegetal matter. It is a product between peat and lignitic coal. An analysis, taken from Coal Resources of the World shows the approximate composition of the material: Moisture, 53.73 per cent.; ash, 4.98; fixed carbon, 18.08; volatile carbon, 23.31 per cent. The principal characteristic is the amount of moisture. This seldom runs less than 48 per cent. The ash is usually low and ranges from 5 to 10 per cent. The sulphur content is usually less than 0.5 per cent. The heating effect of the fuel ranges from 2,000 to 2,500 calories.

Jan 2, 1916

By T. K. Prentice

The January-February number of the Journal of the Chemical Metallurgical and Mining Society of South Africa, 1943, is made up entirely of a discussion of Ball Wear in Cylindrical Mills. Following the principal paper by T. K. Prentice are several remarkably pertinent and carefully prepared discussions. Few persons in this country would be likely to see this publication, and since the information presented is new and of current interest, it seems desirable to abstract and review this publication for the benefit of the members of the A.I.M.E. The purpose of the investigation is stated in the first two paragraphs of Prentice's paper, as follows: Early in 1941, The Chamber of Mines Steel Products, Limited, initiated a series of tests under semi-working scale conditions to determine, if possible, those physical and chemical properties of a ball which make it resistant to wear when used in a cylindrical mill as a grinding medium, with the primary object of incorporating those beneficial qualities in the balls being produced at their works. This paper describes the tests carried out and discusses the results obtained. From these results it was possible to formulate a new theory relating to ball wear in cylindrical mills. This theory is presented in the second portion of this paper. Practical Ball-mill Tests in a Cylindrical Mill Part I of the paper begins with a discussion of the methods used for the manu- facture of grinding balls in South Africa. The following paragraph is of particular interest. The cast steel ingots, 4¼ in. square by 3 ft. 6 in. long, are re-heated in a gas-fired sloping stationary-hearth furnace and then rolled in a six-pass continuous mill into 25/8 in. round billets. Some of these billets are then removed and cut into suitable lengths for forging into 4 in., 3¼ in. , 3 in. or 2½ in. balls by means of three Drop and two Beche hammers, but the greater number, whilst still at about 1,000, pass directly into a set of scroll rolls which produce, in an ingenious manner, finished 3 in. balls direct from the 25/8 in. billets. Except in special cases, all balls are allowed to cool in the atmosphere and are not water quenched. Details of the Tests In order to enable the reader to evaluate properly the results and conclusions in the rest of the paper and in the discussions following the paper, most of the information presented by the author under this heading is quoted: The testing unit was a nominal 30 in. diameter and 18 in. long centre discharge Denver Ball Mill. The ore pulp to the ball mill comprised a small portion of the normal feed to one of the fourteen City Deep 5 ft. 6 in. X 22 ft. tube mills, and the grinding media consisted of the balls under test plus other balls to give the desired load. The running time of the test-mill was divided into approximately equal periods of five days 13½ hours each. The usual procedure was to examine and make up the load

Jan 1, 1947

By T. K. Prentice

The January-February number of the Journal of the Chemical Metallurgical and Mining Society of South Africa, 1943, is made up entirely of a discussion of Ball Wear in Cylindrical Mills. Following the principal paper by T. K. Prentice are several remarkably pertinent and carefully prepared discussions. Few persons in this country would be likely to see this publication, and since the information presented is new and of current interest, it seems desirable to abstract and review this publication for the benefit of the members of the A.I.M.E. The purpose of the investigation is stated in the first two paragraphs of Prentice's paper, as follows: Early in 1941, The Chamber of Mines Steel Products, Limited, initiated a series of tests under semi-working scale conditions to determine, if possible, those physical and chemical properties of a ball which make it resistant to wear when used in a cylindrical mill as a grinding medium, with the primary object of incorporating those beneficial qualities in the balls being produced at their works. This paper describes the tests carried out and discusses the results obtained. From these results it was possible to formulate a new theory relating to ball wear in cylindrical mills. This theory is presented in the second portion of this paper. Practical Ball-mill Tests in a Cylindrical Mill Part I of the paper begins with a discussion of the methods used for the manu- facture of grinding balls in South Africa. The following paragraph is of particular interest. The cast steel ingots, 4¼ in. square by 3 ft. 6 in. long, are re-heated in a gas-fired sloping stationary-hearth furnace and then rolled in a six-pass continuous mill into 25/8 in. round billets. Some of these billets are then removed and cut into suitable lengths for forging into 4 in., 3¼ in. , 3 in. or 2½ in. balls by means of three Drop and two Beche hammers, but the greater number, whilst still at about 1,000, pass directly into a set of scroll rolls which produce, in an ingenious manner, finished 3 in. balls direct from the 25/8 in. billets. Except in special cases, all balls are allowed to cool in the atmosphere and are not water quenched. Details of the Tests In order to enable the reader to evaluate properly the results and conclusions in the rest of the paper and in the discussions following the paper, most of the information presented by the author under this heading is quoted: The testing unit was a nominal 30 in. diameter and 18 in. long centre discharge Denver Ball Mill. The ore pulp to the ball mill comprised a small portion of the normal feed to one of the fourteen City Deep 5 ft. 6 in. X 22 ft. tube mills, and the grinding media consisted of the balls under test plus other balls to give the desired load. The running time of the test-mill was divided into approximately equal periods of five days 13½ hours each. The usual procedure was to examine and make up the load

Jan 1, 1947

By F. H. Buttner, E. R. Funk, H. Udin

Gold wires, 5 mil in diam, are found to creep viscously up to approximately 5.5x106 dynes per sq cm around 1300°K. Beyond this point, an additional slip mechanism appears. The average coefficient in the viscous range at these temperatures is 18.9 ± 7x10 12 poises. This observation and other visual observations made during the experiments agree with Herring's predictions. EARLY creep studies by Chalmers on single crystals of tin produced some of the first experimental evidence to suggest that metals deform viscously under very light stresses. That is to say, over a small initial stress range up to 150 g per sq mm, the single crystals of tin elongated at a rate proportional to the stress. The proportionality constant between strain rate and stress is by definition the coefficient of viscosity. Chalmers named this range of proportionality the microcreep range. One of the first theoretical attempts to explain the microcreep phenomenon was given by Kauzman,' who applied Eyring'sQ eneral statistical mechanical theory of shear rates to creep data then available. From the rate theory, he deduced the general hyperbolic sine law for shear rate on the assumption that the distortion of the reaction path due to stress is negligible and that the system is an infinite continuum. In order to fit the available data to the equation, it was necessary to assume that creep occurs by shear of rather large blocks of material, rather than by an atomistic shear process as in diffusion. The size of the shear units was shown to increase with increasing temperatures and lower stress, or lower strain rates. In applying the hyperbolic sine law equation to the microcreep data of tin, it was shown by Kauzman that the unit shear blocks became quite small, which suggested to him that microcreep might be a self-diffusion process. Making this an assumption, Kauz- man reworked the rate theory and arrived at an equation where the shear rate is proportional to the stress. In the form of viscosity coefficient, the equation is: o- _ \LkT V = 2qAlA where u is the stress; S, the shear rate; X, the distance in shear direction moved by flow units relative to one another in the unit process; L, the distance between layers of units of flow; T, the absolute temperature; k, Boltzmann's constant; qAL, a constant proportional to the size of flow units; and kT A, the diffusion coefficient = ------kTe-Q/RT = K X2 h Kauzman applied the expression to molten lead with a fair degree of success, the calculated viscosity being low by a factor of four. For solid lead the result is 5000 times too high. Taking q = 1, and X = dA = L = 21 = nearest neighbor distance, Udin, Shaler and Wulff8 found the equation low by a factor of lo7 for solid copper. On the basis of the discrepancy in lead, Kauzman indicated that microcreep is probably not a simple diffusion process of molecular shear units, but one involving preferential diffusion paths, or even that diffusion in solids does not involve shear at all. Cottrell and Jaswon4 treat the microcreep phenomenon on the basis of slow moving dislocations and apply it to Chalmers' data on tin with fair success. Nabarro Suggested a microcreep model in which mass movement in the direction of pull is effected by the diffusion of holes. The tension on the crystal effectively creates a greater hole concentration at regions near the crystal surfaces perpendicular to

Jan 1, 1953

By T. K. Prentice

ABSTRACTED AND REVIEWED BY E. W. DAVIS,* MEMBER A.I.M.E. THE January-February number of the Journal of the Chemical Metallurgical and Mining Society of South Africa is made up entirely of a discussion of Ball Wear in Cylindrical Mills. Following the principal paper by T. K. Prentice are several remarkably pertinent and carefully prepared discussions. Few persons in this country would be likely to see this publication, and since the information presented is new and of current interest, it seems desirable to abstract and review this publication for the benefit of the members of the A.I.M.E. The purpose of the investigation is stated in the first two paragraphs of Prentice's paper, as follows: Early in 1941, The Chamber of Mines Steel Products, Limited, initiated a series of tests under semi-working scale conditions to determine, if possible, those physical and chemical properties of a ball which make it resistant to wear when used in a cylindrical mill as a grinding medium, with the primary object of incorporating those beneficial qualities in the balls being produced at their works. This paper describes the tests carried out and discusses the results obtained. From these results it was possible to formulate a new theory relating to ball wear in cylindrical mills. This theory is presented in the second portion of this paper. PRACTICAL BALL-MILL TESTS IN A CYLINDRICAL MILL Part I of the paper begins with a discussion of the methods used for the manufacture of grinding balls in South Africa. The following paragraph is of particular interest. The cast steel ingots, 4 ¼ - in. square by 3 ft. 6 in. long, are re-heated in a gas-fired sloping stationary-hearth furnace and then rolled in a six-pass continuous mill into 2 5/8 in. round billets. Some of these billets are then removed and cut into suitable lengths for forging into 4 in., 3 ½ in., 3 in. or 2 ½ in. balls by means of three Drop and two Beché hammers, but the greater number, whilst still at about 1,000 ºC., pass directly into a set of scroll rolls which produce, in an ingenious manner, finished 3 in. balls direct from the 2 5/8 in. billets. Except in special cases, all balls are allowed to cool in the atmosphere and are not water quenched. Details of the Tests In order to enable the reader to evaluate properly the results and conclusions in the rest of the paper and in the discussions following the paper, most of the information presented by the author under this heading is quoted: ….. The testing unit was a nominal 30 in. diameter and 18 in. long centre discharge Denver Ball Mill. The ore pulp to the ball mill comprised a small portion of the normal feed to one of the fourteen City Deep 5 ft. 6 in. X 22 ft. tube mills, and the grinding media consisted of the balls under test plus other balls to give the desired load. The running time of the test-mill was divided into approximately equal periods of five days 13 ½ hours each. The usual procedure was to examine and make up the load

Jan 1, 1944

Apart from the general cooperation received in many quarters, the Unitization Committee desires to make specific acknowledgment to the following individuals for assistance rendered in the study to this time. California.—Committee members: Joseph Jensen, chairman, L. L. Brundred, E. M. Butterworth, H. Norton Johnson, D. B. Myers, W. R. Wardner; others who contributed: C. R. McCollom, F. C. Merritt, E. B. Noble, Ralph Arnold, J. R. Pemberton, Roy R. Morse, T. F. Stipp, John R. Roberts, R. D. Bush, Alexander Anderson, J. A. Taff, F. 0. Martin, J. E. Van Gundy, E. K. Parks, A. C. Rubel, Lew Suverkrop, W. L. McLaine, Gerard Henny, Walter Stalder, Lester C. Uren, Hoyt S. Gale, W. L. Walker. Rocky Mountain.—Fred E. Wood, chairman, J. G. Bartram, C. E. Dobbin, Wilson B. Emery, Charles E. Erdman, R. D. Hawley, E. W. Krampert, Foster Morrell, W. T. Nightingale, K. B. Nowels, C. M. Rath, Earl Shoenfelt, J. W. Steele, E. T. Wilson, J. J. Zorichak. Kansas-Oklahoma.—Committee members: C. E. Beecher, chairman, A. W. Ambrose, R. C. Hauber, Clyde Alexander, R. F. MacArthur, C. R. Swarts, M. M. Valerius, E. H. Griswold, G. 6. Rollin, L. Murray Newman, David L. Trax, Richard K. Huey, Marvin Lee, Harry Johnson; others who contributed: E. A. Carr, Paul S. Ache, K. C. Slater, R. S. McFarland, J. R. McWilliams, Joseph Chalmers, Henry A. Ley, Dorsey IIager, H. C. George, W. K. Whiteford, L. G. E. Bignell, L. E. Smith, George E. Burton. Texas, Louisiana, Arkansas, New Mexico.—Frederic H. Lahee, chairman, Donald C. Barton, C:. E. Beecher, Olin G. Bell, G. E. Campbell, Paul Wagner, John West, Robin Willis, J. M. Forgotson, E. J. Gorman, P. S. Haury, Marvin Lee, C. F. Lytle, L. H. McBee, T. F. Petty, C. C. Pope, F. S. Prout, J. C. Stewart, J. R. Suman, L. P. Teas, W. C. Thompson, A. F. Truex, R. B. Campbell, M. G. Cheney, P. C. Dean, F. W. DeWolf, Dugald Gordon, B. A. Hardey, F. E. Heath, J. F. Lucey, George C. Matson, W. H. Perot, T. W. Pew, W. A. Price, W. A. -Reiter, R. C. Stewart. Eastern United States and Foreign Fields.—H. H. Hill and E. L. Estabrook, chairmen; Dr. Richard Ambronn, Gottingen, Germany; Arthur R. Andrew,

Jan 1, 1930

By Lyman Taylor, Alexander R. Troiano

STUDIES of the transformation of austenite at constant subcritical temperatures have been numerous since the work of Davenport and Bain.1 Considerable information has been obtained on low-alloy steels and on high-carbon alloys containing undissolved carbide or graphite at the austenitizing temperature. Little is known of the isothermal transformation of austenite containing in solution large amounts of both carbon and a single alloying element. In this investigation four steels containing one per cent carbon and with chromium in the range 3 to 9 per cent have been examined with the view to establishing the fundamental character of the isothermal reactions when all carbon and chromium are initially in solution in austenite. EXPERIMENTAL PROCEDURE Alloys The chemical compositions of the steels investigated are given in Table I. The 4 per cent Cr alloy is a commercial steel. The other steels were made by the Carpenter Steel Co. as 50-lb., induction-furnace heats and rolled to 5/8-in. round bars. Bars were softened at 650° to 700°C. before the specimens were cut. [ ] Metallographic Method Most of the lines on the transformation diagrams presented here have been placed on the basis of the microscopic examination of partially reacted specimens. Thees specimens were approximately ½ by ¼ by 1/8 in. in size. Specimens of the 9 per cent Cr steel were held 10 to 12 hr. at 1200° to I225°C. before quenching to the various subcritical temperatures. The other steels were held for 2 to 2 ½ hr. at 1200°C. before quenching. These treatments, carried out in an atmosphere of purified nitrogen, produced an austenite grain size larger than A.S.T.M. No. I, some grains being 1 to 2 mm. in diameter. There were a few undissolved carbide particles in some specimens of the 9 per cent Cr steel. It is believed, however, that any errors in the results due to incomplete solution of carbon and chromium in austenite are negligible; that is, austenite compositions may be considered as being those listed in Table I. X-ray Methods Constituents were identified and martensite axial ratios determined from Debye

Jan 1, 1945

By C. F. Jr. Park

HOG MOUNTAIN is in the north central part of Tallapoosa County, Alabama, about 13 miles northeast from Alexander City. The Hog Mountain Mining and Milling Co. controls 1658 acres of land and is the only company operating in the district. The principal mine workings are in sections 10 and 15, T.24N., R.22E. The region has been visited by geologists many times, has been briefly described in several papers,1 and mentioned in many others. No detailed map of the mine or vicinity has been published. The field work for this report was started in March, 1934, as part of the Public Works reemployment program. About a month and a half was spent mapping both the surface and underground geology. The mine owners and operators have cooperated in every way possible to facilitate the work. N. 0. Johnson, the mine engineer, E. W. Ells-worth, J. E. McCoy and J. G. Englebert have acted as assistants for part of the work. The University of Alabama and the State Geologist's office have aided materially by permitting free use of their libraries and laboratory equipment.

Jan 1, 1935

By Francis Foley

IN THE first report1 disks of steel of- known composition and history were exposed, under carefully prescribed conditions, to impacts of explosion products resulting from the explosion of 50-gm. charges of explosives having well-determined rates of detonation, or to, impacts of a weight of known mass, falling through measured distances. There were available at the Bureau of Mines Experiment Station five explosives, having rates of detonation of 5716, 4470, 3190, 2296, and 1523 meters per second. It being desired to continue this exposure downward, and no explosives with a lesser rate of detonation being at hand, resort was had to the impact of a falling weight, the differences in the velocity of impact being attained by varying the height from which the weight was allowed to fall. It was expected by this means to demonstrate experimentally that the development of Neumann bands was determined by the suddenness of the deformation of the metal in which they were produced. But while progressive deformations were obtained with the explosive charges, the falling-weight method failed because the tup was progressively deformed, also the disks were so flattened as to be unfit for metallographic examination. A return, therefore, has been made to the use of explosives as the source of energy, an air-gap being interposed between the charge of explosive and the disk, as the effect diminishes as the function of the distance between the charge and the object on which the products of its explosion, or the shock wave from its detonation, impinge. The details of the arrangement of the tests by the air-gap method were the same as those described by Foley and Howell,2 except that after the system had been set up and the desired apparent specific gravity for the explosive

Jan 2, 1926

By C. C. Furnas, T. L. Joseph

It is well known that particles of different sizes are not distributed evenly throughout the average charge in an iron blast furnace. Just how great the disparity in particle size in different parts of a single plane in a furnace may be is indicated by the results of some recent investiga-tion1,2 conducted by the Bureau of Mines on a furnace operating on Lake ores. The wide variations found in gas velocity, gas composition, and temperature from the periphery to the center of the upper charge column were caused by the great variation in particle size of the raw materials used and were also greatly influenced by the methods of charging. This paper summarizes the results of an investigation of the influence of different methods of charging and of the treatment of raw materials upon the size distribution of the solid particles in the blast furnace. A more complete report will appear later as a Bureau of Mines technical paper. Importance of Gas-solid Contact One of the authors has pointed out in a previous report? that the operation of the blast-furnace process is entirely dependent on contact between the gas stream and the solid particles in the stock. The gas stream carries the necessary heat as well as the carbon monoxide molecules that do the work of rednction. In the parts of the furnace in which there is little or no contact between the gas stream and the solids there can be little work of reduction. Obviously, the part of the apparatus that is not doing the work for which it is intended is inefficient; the ideal condition is one in which all portions of the stock column are

Jan 1, 1929