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By L. S. Chabot

INTRODUCTION THE bibliography of mining methods in the past few years has contained many articles dealing with the use of the diamond drill for blasthole drilling. In the Canadian mines, this method has been used with great success in stoping at Noranda, Aldermac, Waite Amulet, East Malartic and Sladen Malartic mines in the Province of Quebec. It has also been used at the Dorchester and Beattie gold mines in Duparquet, Quebec. The method has found useful application at Copper Mountain mine, British Colombia, and at Flin Flon mine in Manitoba. In the United States, the diamond drill blasthole method has been used at Cornwall Iron Ore Mines in Pennsylvania and at the Republic Steel Corporation magnetite properties in the Port Henry district of northern New York. In the Lake Superior iron district, the method has been used at the Anvil-Palms mine of Pickands, Mather and Co. at Bessemer, Mich., and is also used at the Book mine of the North Range Mining Co. at Alpha, Mich. Other companies in the district have also experimented in some degree with the method at some of their properties. This paper is being offered as a preliminary report on the use of the diamond drill method of stoping at the Book mine. Sufficient work has been done with it to prove its worth and it is the purpose of the article to present some results, operational details, equipment ideas and recommendations which we have found in its use at our mine. LOCATION AND DESCRIPTION The Book mine is situated about a mile north of the village of Alpha, in the NE-NE ¼ and the SE-NE ¼ of sec 12-42-33, between the Dunn mine and the Balkan-Judson mine, and about four miles southwest of the village of Crystal Falls, on the Menominee Range of Michigan. The property was found to have ore near surface in sufficient quantities for open-pit operations and stripping was begun in the latter part of 1942 to prepare it for ore production in 1943. During 1943, 288,447 tons of direct shipping ore were produced from the open pit and 382,933 tons in 1944. While the mine was being operated as an open pit some 350,000 tons of lean ore were stockpiled for later treatment. This material is being treated in a washing and jig plant and concentrates are produced during the shipping season. The ore bodies at the Book mine are characteristic of the Menominee Range. They are found on the flanks of sharply folded anticlines which have a fairly steep pitch to the northwest. The open-pit operations in 1943 and 1944 revealed two of these anticlinal structures. A detailed study and classification of the old diamond drill records, coupled with the information of some new holes drilled, has established the

Jan 1, 1947

By Tell Ertl, Ernest E. Burgh

INTRODUCTION THE Bureau of Mines is operating an oil-shale mine 10 miles west of Rifle, Colo., as part of its Synthetic Liquid Fuels program. The purpose of operating this mine is twofold: First, to supply oil shale to an experimental processing plant; and second, to develop practices and select methods for mining oil shale on a commercial scale at the lowest practicable cost. The second purpose-that of finding out how to mine oil shale most cheaply-entails considerable mining research. Since the drilling of oil shale probably will be one of the major items of the mining cost, factors that influence drilling speeds were investigated. One phase of the drilling program was the development of a successful hard-surfaced rock-drill bit1 that can be used for drilling long holes in oil shale without changing bits. During that phase, drilling speeds were measured and drill cuttings were collected for assay and for screen sizing. When the cuttings from the individual tests were compared, a definite relationship was shown to exist between the drilling speed and the coarseness of the drill cuttings. PROCEDURE Measurement of Drilling Speeds All drilling in the tests was done with a Model UMB-D-99W Gardner-Denver wagon drill. Round-lugged drill steel, 1 ¼ in. in diameter was used in 6, 12, and 18 ft lengths with 2 1/8 -in. Timken H-type bits hard-faced with acetylene tube borium. The tests were made in the lower adit of the Bureau of Mines oil-shale mine; the grade of the oil shale drilled ranged from 18.6 to 42.7 gal per ton. During the experiments air pressure varied between 75 and 90 psi while water pressure remained fairly constant at 75 psi. All holes were drilled almost horizontally. Each drill hole was thoroughly cleaned of cuttings after being collared. The advance of the drill along the carriage was measured and recorded as the drilling speed in inches per minute. Method of Collecting Cuttings To facilitate the collection of cuttings, each drill hole was collared in a smooth, vertical portion of the oil-shale breast (Fig 1). A galvanized-steel sheet was fastened to the breast below the area in which the hole was to be drilled. The cuttings washed out of the drill hole by the drilling water were guided by the steel sheet into a wooden box. The cuttings that remained in the drill hole after the drill was withdrawn were scraped out and placed in the same box as the cuttings washed out of the hole. After the cuttings from a 1-min. drilling interval were collected, they were placed in flat metal pans. The fines were allowed to settle and the clear water was decanted. The cuttings then were dried in the sun.

Jan 1, 1947

By H. L. Talbot, A. J. Hall, R. S. Young

A METHOD for the chemical differentiation of oxidized cobalt from sulphide cobalt in complex mine and concentrator products is of considerable interest to a number of mining companies throughout the world. At Rhokana Corporation, in Northern Rhodesia, for instance, cobalt is found chiefly in the sulphide form, as carrollite, but a cobalt oxide mineral also occurs irregularly underground, and relatively small quantities in the mill feed from time to time are difficult to detect it visually at the concentrator. The oxide cobalt is not amenable to the sulphide flotation process used at Rhokana and nearly all of it passes into the tailing. The occasional. period when high tailing losses occur with no appreciable change in the cobalt content of the mill feed has naturally been disturbing to the concentrator staff, who had no means of determining whether an influx of cobalt oxide ore or laxity on the part of the mill flotation operators were responsible for these results. A procedure for determining oxidized copper minerals, based on their solubility in dilute sulphuric acid saturated with SO2, has been used for many years in the copper industry. In the presence of cuprite the procedure fails, but otherwise it gives results quite satisfactory for control purposes. Empirical methods for determining oxidized forms of zinc and lead have been proposed, but they are generally unsatisfactory except in isolated cases of a very simple ore. No published procedure for determining oxidized forms of cobalt or similar elements has come to the authors' notice. EXPERIMENTAL PROCEDURE There are obviously two alternatives in attacking a problem of this nature. One is to employ a solvent for oxide cobalt that will not dissolve cobalt sulphide. The other is, to find a substance capable of oxidizing the cobalt sulphide to sulphate, which of course is water-soluble and can then be leached from the water-insoluble oxide cobalt. A representative sample of Rhokana cobalt oxide ore was secured, ground to minus 200-mesh, and carefully rolled to furnish a standard sample for this work. The analysis of this material gave the following percentages: Co, 0.55; Cu, 1.64; Fe, 2.98; S, 0.08; SiO2, 41.42; A1203, 11.20; CaO, 13.82; MgO, 3.80. As a source of cobalt sulphide a similar large sample of carrollite was prepared, analyzing Co, 23.36 per cent; Cu, 27.32; and S, 31.13. This sample of course was not pure carrollite, but was the best obtainable in quantities sufficient for a standard intended for considerable work. It was a pure sulphide sample, microscopic examination showing only carrollite, a little bornite, and gangue, with no visible sign of oxidized ore present. A wide variety of reagents were used in an effort to selectively dissolve oxide cobalt or to oxidize sulphide cobalt to

Jan 1, 1946

The Carlin gold deposit is located in northeastern Nevada about thirty-five miles by road from the town of Elko. Following the staking of six square miles 'of ground, a drilling program outlined a fine ore body mineable by open pitting. The resulting mine turned out to be the largest open-pit gold operation in the world, until the Rosario Pueblo Viejo operation was started in 1975. Because of the high profitability forecast at the then $35 gold price, construction of a 2000 stpd mill was commenced on a crash program and was completed for Newmont Mining Corporation by Bechtel Corporation in ten months. Production was started in early 1965. The gold mineralization occurs in marine-type sediments, chiefly silt- stones and limey shales, and the ore characteristics make for a difficult materials-handling problem. At 5% to 6% moisture the ore is dusty during crushing, but even a light rain or snowfall virtually turns the material into a slurry. Crushing this sticky ore below 314 in. (19 mm) in the dry season and 1 in. (25.4 m) during the winter is extremely difficult and leads to problems with conveyors, chutes, and fine ore storage. The initial flowsheet for Carlin's crushing plant used a 5 ft by 22 ft (1.52 m by 6. 7 m) vibrating feeder -grizzly under the 60 -ton dump pocket for feeding the 42 in. by 48 in. (1067 mm by 1220 mm) single toggle jaw crusher and a 5 ½ ft (1.52 m) standard cone crusher in closed circuit with a 6 ft by 12 ft (1.83 m by 3.66 m) vibrating double - deck screen. Because continual packing of fines in the vibrating feeder pan would cause frequent plant shut-downs to remove the fines with jack hammers, the decision was made to replace the vibrating unit with an apron feeder and stationary grizzly ahead of the jaw crusher. A dribble belt was also installed under the apron feeder. This installation has greatly improved the feeding of the pit run ore to the .primary jaw crusher. Mining at Carlin is done by a 5 yd shovel and 7 ½ and 10 yd front-end loaders, and ore transport is by several sizes of trucks from 30 to 75 tons capacity. These pit haulage trucks dump onto stockpiles adjacent to the primary crusher. Ore is then fed to the dump hopper by front- end loaders only when the crushing plant is operating. This extra handling procedure is necessary because plant delays caused by problems with wet ore in the secondary crusher resulted in the ore setting up or packing in the dump pocket. Solidified material in the dump pocket would in turn delay truck haulage. The substitution of an

Jan 1, 1978

By J. J. Gilman

Rates of prisnzatic plastic glide ( {1010}<2110>) in pure Cd crystals have been measured at temperatures from 158° to 276°C. The glide rate is proportional to the 2.75 power of the applied shear-stress. The activation energy is 29.2 kcal per mol. It is suggested that the rates of prismatic glide in Cd and Zn crystals are determined by the strengths of the atomic bonds across the prism planes. ALTHOUGH zinc and cadmium crystals both have hexagonal structures with nearly the same c/o ratios, their mechanical behaviors are quite different. Whereas zinc becomes quite brittle below room temperature, and cleaves readily on (0001) planes, cadmium is very ductile even at 4.2°K, and cannot be cleaved at any temperature. As part of a search for the explanation of this difference in behavior, a study has been made of prismatic glide in cadmium. It complements a previous study of the same phenomenon in zinc.1 The primary glide plane in cadmium is the basal (0001) plane, and the primary glide direction is the direction of atomic close-packing <2110>. However, if a tensile stress is applied parallel to the basal plane, then the shear stress on the basal plane equals zero so basal glide cannot occur. At low temperatures, deformation by twinning occurs; but at high temperatures, it has been found in this study that gliding on prismatic planes (1010) occurs in the close-packed direction. This is completely analogous with the case of zinc, except that lower temperatures are required. EXPERIMENTAL The experiments were done in nearly the same way as for zinc.&apos; Therefore, only the differences in the two sets of experiments will be described here; for other details the reader is referred to the previous paper. Crystals 6 by 6 mm sq were used that were grown from "Super Purity" 99.999 + pct Cd purchased from the New Jersey Zinc Co. The crystals were grown with their basal planes parallel to both the rod axis and one of the flat sides of the square cross section, A close-packed direction in the basal plane was oriented parallel to the rod axis. Gage sections were carefully machined into the crystals, and the surface damage caused by machining was removed with the same chemical polishing reagent as had been used for zinc. Thus, specimens of the same form and size as the previous zinc ones were produced. The crystals were heated to the test temperatures in a silicone oil bath (fused salts were tried first, but they reacted badly with the cadmium). An Instron tensile-testing machine was used for applying stresses to the crystals at various constant strain-rates. RESULTS The general behavior of cadmium crystals is much the same as for zinc. Only the constants that measure specific properties are different. Just as

Jan 1, 1962

By H. A. Coy

THE Mascot mines of the American Zinc. Co. of Tennessee are situated at Mascot, Tenn., 14 miles northeast of Knoxville, on the Southern Railway. The district is centrally located in the Great Valley, or Appalachian Valley Province. Prior to 1900, a small output of zinc was obtained from oxidized ore mined in open pits. In 1900, a shaft was sunk to sulfide ore, and in 1903, a second shaft was put down, neither being as deep as 200 ft. The American Zinc Co. of Tennessee began drilling in 1911, and outlined an ore body to which its No. 1 shaft was sunk, to a depth of 365 ft. Since that time, the American Zinc Co. of Tennessee has been the only operator in. the district. The Federal mining laws have never been in operation in Tennessee and mining lands are as irregular in boundary and area as farm lands. Ownerships are generally held in fee. In most cases the surface and mineral rights, are transferred together. Electric power is supplied at 66,000 volts by the Tennessee Power do, from a hydro-electric plant at Parksville, Polk County, Tenn., 100 miles from Mascot. No other power is used, but an emergency steam plant is held ready in case of interruption of service. Labor is all native and non-union. Negroes are employed for most of the shoveling, and for a few miscellaneous jobs, but for almost, no other work.

Jan 9, 1924

By J. E. Crawshaw, Francis B. 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 attained by tamping it, the small lead block, with the steel disk adhering

Jan 1, 1926

By C. H. Chou, A. Sauveur

The senior author of this paper has expressed the belief that when gamma iron transforms into alpha iron on reaching the A3 point, each gamma grain does not change bodily into one or more alpha grains but that the alpha phase forms first at the boundaries and along the crystallo-graphic planes of the austenite grains.1 To quote: On cooling through the point As, at about 900° C, iron passes from the gamma condition to a new allotropic form generally designated as alpha. This transformation, however, is not instantaneous. There are good reasons for believing that it begins at the grain boundaries and along the octahedral planes of the crystals and that it progresses until each grain of gamma iron is changed into a grain of alpha iron, the resulting structure being similar to that of gamma iron. Were it possible to retain

Jan 1, 1929

By C. H. Mathewson

MICROSCOPIC rnetallography has been exploited quite well enough to bring about a very general understanding that the typical metal or alloy is composed of minute crystalline particles blended into a coherent microstructural mosaic. One does not have to be a specialist in metallography to realize that the properties of such an aggregate are essentially a summation in appropriate form of individual effects derived from the shape, size, placement or orientation and cohesive characteristics of the component particles. It is clearly of great importance to consider the various forms of discontinuity which may occur at the boundaries between these crystalline particles. When a number of particles each possessing the same orderly arrangement of atoms are brought together into a close-fitting system of purely haphazard contacts, not unlike a handful of snowflakes compacted into a snowball, the particles are said to possess random orientation. There are no generally accepted views concerning the arrangement of the atomis or the constitutional reaction between atoms where one crystal meets another, but these contact regions are characterized by strength rather than weakness and it is customary to require the presence of many rather than few boundaries in preparing metal for useful service. Under certain circumstances all of the particles in a metal may be nearly alike in orientation. Other general tendencies of orientation may be associated with particular forms of mechanical and thermal treatment. In contrast with these cases of fortuitous or statistical diversity of orientation, we often find adjacent particles united along a plane which possesses a grouping of atoms belonging equally well to both structures. This, of course, determines a fixed relationship between the two orientations and it is always possible to derive one from the other by some form of rotation or reflection prescribed by the symmetry of the crystal structure under consideration. Particles united in this manner are known as twin crystals although the term refers to the form of association rather than the number of individuals concerned.

By Francis Clark

WHEN 60:40 brass is heated to 825° C., given a drastic quench to obtain the beta solid solution, and reheated, various changes take place in the structure. Reheating at 200° C. causes a fine, granular, sorbitic structure to appear which has been considered alpha solid solution. These particles coalesce at higher temperatures of reheating, and at 470° C., the alpha forms twins. A further study of these transformations was considered worth investigating. EXPERIMENTAL WORK The object of the experimental work was to study the effect of mechanical work on rolled 60:40 brass, quenched and reheated, and the mechanism of twinning in the alpha reeds of a furnace-cooled specimen. It was desired to determine the effect of mechanical work on the transformations taking place on reheating the quenched material, both at 200 and at 470° C. A study of the nature of the structure resulting from the breakdown of the beta at 200° C. and a study of the mechanism of twinning above 470° C. were considered problems for investigation. The question of the twinning of the alpha reeds was also an important phase of the work. With high-power magnifications, there was hope of following these processes.

Jan 1, 1927

By Bernard York, John J. Reed

W. 0. Philbrook (Carnegie Institute of Technology, Phila.)—Mr. DeVaney&apos;s paper is a valuable addition to the growing technology of the magnetic roasting of lean iron ores. His furnace is ingeniously designed to permit close control of the process and to achieve high thermal efficiency by counter-current heat exchange and the withdrawal of both solid and gaseous products at relatively low temperatures. The principle of using a lean reducing gas to avoid over-reduction of the ore even at high operating temperatures (for rapid reaction rate) is thoroughly sound. The gas analyses and flow rates reported, however, are internally incon- sistent and render suspect any details of a heat balance based upon them. While it is entirely proper to consider the entrant gas as a reagent and to account only for the heat evolved by consuming a portion of the gas, many operators are accustomed to a heat balance using the total calorific value of the reagent supplied; and comparison of heat balances made with different bases of calculation can be quite misleading. Since Mr. DeVaney&apos;s paper is likely to be cited frequently in future discussions of magnetic roasting processes, it seems worth while to point out the internal discrepancies and to give alternate values of heat requirements for different bases of calculation.

Jan 1, 1954

By Frank Firmstone

Since the blast Fired August 15th, 1878, which was described by Mr. Clark," and up to November, 1881, we have fired three smaller blasts, one in the southwest corner of the quarry and two in the buttress of rock left standing by the first blast near the mouth of the main gangway. We intended to keep an exact account of the stone thrown down by each blast, but the large quantity required by the furnaces since the beginning of 1879, and the time taken up by more important matters, have caused this to he neglected, so that it is not possible to separate exactly the cost and quantity of stone obtained during this time by the old method from that furnished by the large blasts; yet as the latter quantity has been much greater than the former, some notion of the value of the large-blast plan may be reached by comparing the figures from September, 1878, to November, 1881, with those for times when the old system was exclusively used. Since 1878 wages have been raised, lowered, and again raised, and to get a year of sufficiently large production for fair comparison it is necessary to go back to that ending April, 1872, when wage? and supplies were different from present prices and from those of 1878,.

Jan 1, 1882

By Frank Firmstone

SINCE the blast fired August 15th, 1878, which was described by Mr. Clark,* and up to November, 1881, we have fired three smaller blasts, one in the: southwest corner of the quarry and two in-the but-tress of rock Left standing by the first blast rear the mouth of the main gangway. We intended to keep an exact account of the stone thrown down by each blast, but the large quantity required by, the furnaces since the beginning of 1879, and the time taken up by more important matters, have caused this to he neglected, so that it is not possible to separate exactly the, cost and quantity of stone obtained during this time by the old method from that furnished by the large blasts; yet as the latter quantity has beet much greater than the former, some notion of the value of the Jarge-blast plan may be reached by comparing the figures from September, 1878, to November, 1881, with those for times when the old system was exclusively used. Since 1878 wages have been raised, lowered, and again raised, and to get a year of sufficiently large production for fair comparison it is necessary to go back to that ending April, 1872, when wages and supplies were different from present prices and from those of 1878. * Transactions, vol. vii, p. 266.

Jan 1, 1882

In accordance with the requirements of By-Law LX,- I beg leave to submit herewith the report of the Library Committee for the year 1916. The activities shown by the sale of the Institute&apos;s publications during the year are somewhat larger than last year, due principally to the increased sale of special editions on account of the larger sale of the Posepny and Emmons Volumes, owing to increased advertising and to the reduction in price of the Emmons Volume. The sales were distributed as follows: Sale of Transactions $3,237.07 Sale of Special Editions 1,722.50 Sale of Bulletins and Pamphlets 2,263.95 Total $7,223.52, The Institute library has now been merged with the libraries of the. other three Founder Societies and is known and administered as the Library of the United - Engineering Society. When this merger, was effected, a proviso was made that the books contained in the Institute library up to the date of the merger were still to be considered as the individual property of the Institute, and this arrangement applied also to the libraries of the other two Founder Societies. At the time that the American Society of Civil Engineers joined as a fourth Founder Society, they immediately turned over their entire library to the United Engineering Society, relinquishing all property rights in the books entirely.

Jan 2, 1917

By C. W. Goodale

As an appendix to the above-mentioned paper, a drawing of the vertical projection of the Knoxville mine workings is here given. In my paper it was stated that the ore-chimneys are found along a crack or plane of cleavage in the limestone ; and as this crack is not parallel with the strata, it is safe to assume that the manganese was not deposited where it is now found before the tilting-up of the strata, but rather that the crack was caused by the folding, and that tile formation of the ore was entirely subsequent to the change of position of the limestone. There are here four chimneys, which have produced, as far as explored, over 12,000 tons of ore, containing at least 7000 tons of manganese oxides, and it is very difficult to apply Prof. W. P. Blake&apos;s theory of segregation from the surrounding limestone in accounting for the origin of this ore, as cross-cuts and drifts in the countryrock, even at short distances from the ore-chimneys, have not shown manganese in appreciable quantities. It is easier to believe that, in the language of .Mr. S. F. Emmons, in speaking of Leadville ore-deposits, there was a metasomatic interchange between the minerals brought in in solution and the limestone, and not a deposition in already existing cavities. This in-

Jan 1, 1890

By E. B. Branson

Introduction to Geology, by E. B. Branson, W. A. Tarr, and W. D. Keller, revised-by Carl C. Branson. McGraw-Hill, 1952. $5.50.-Dealing with physical and historical geology, the book has been revised from an earlier edition. An attempt has been made to eliminate unnecessary detail in discussing processes and history. Revisions bring technical and statistical data up-to-date, and follow suggestions by teachers who used earlier editions. The book carries an eye witness account of the severe earthquake in Assam, India, in 1950 and the story of Paricutin and other major examples of volcanism. Charts summarize chemical weathering, and the results of metamorphisms. The book also contains many new illustrations, including aerial photographs. A History of Phelps Dodge 1834-1950, by Robert Glass Cleland. Alfred A. Knopf, 1952. $4.00.-The book traces the growth of Phelps Dodge from the day Anson Greene Phelps opened a small saddle shop in Hartford, Conn., to the present day. As the country grew, so did Phelps Dodge. The company took part in large affairs from its very beginning. It bought and sold, exported and imported, built factories and railroads, and widened its scope of operations economically and geographically. Entrance of Phelps Dodge into copper mining and the gradual giving up of other interests in favor of the new venture is traced.

Jan 1, 1952

By Frank Firmstone, Kenneth Robertson

Peculiar crusts having appeared on certain irons made at Glendon and Pequest, which, in our experience, were entirely new, some analyses of them were made; and these analyses, together with an account of the manner of appearance of the crusts, are herewith submitted to the Institute. At Pequest the ores mere: & Peters, from Ringwood, N. J.; + roasted sulphurous ore, from Charlotteburgh, N. J.; and + red ore (decomposed magnetite), from Chester, N. J. The fuel was 7/8 Lehigh anthracite and + Connellsville coke, and the limestone a dolomite from Andover, N. J. The resulting iron varied in silicon from 0 84 per cent. in No. 1 foundry to 0.51 per cent. in gray forge; in phosphorus, from 0.81 per cent. to 0.55 per cent.; sulphur, 0.035 per cent.; manganese, 0.375 per cent. It was highly "chilling" in its properties, and very strong. In running, it invariably appeared to be of a lower grade than it really was; the higher grades scintillating as much as hard iron usually does. After getting into the moulds, and beginning to cool, a black crust began to show itself, seeming to exude from the pigs, till finally, when the iron was cold enough to break, it completely covered the face of the pigs. At this time it was dense black, but after some exposure to the air it ac .

Jan 1, 1884

By Arthur G. Metcalfe

Arthur G. Metcalfe (SOLAR)—Three explanations to account for mechanical nucleation effects are considered in the paper, viz., theories based on fragmentation, agglomeration, and pressure-wave mechanisms. The authors show that none of these mechanisms will explain the results observed with tin and Sn-Pb alloys. A fourth mechanism of nucleation enhancement was developed during work at Armour Research Foundation on casting of beryllium and, although presented briefly on various occasions, the theory has never been discussed adequately. It is believed that this theory will explain many of the observations. Classical homogeneous nucleation theories assume that embryo nuclei are formed in the melt as a result of compositional and/or thermal fluctuations. Stable nuclei are formed when a critical size is reached such that the decrease in free energy for conversion of this volume of melt to solid offsets the increase of surface, energy. The assumption is made that the average properties of liquid and solid metal can be used. In practice this assumption is invalid and indeed is contrary to the postulation of thermal and compositional fluctuations in the melt. Actually the conditions favoring embryo formation bring the seeds of its own destruction—the thermal and compositional fluctuations leave the embryo surrounded by atoms of higher thermal energies and/or by solute atoms that depress the melting point. Any mechanical method of dispersing this destructive

Jan 1, 1964

One of the results of the work of the Committee on Precious and Base Metals is that the present Bulletin is as large as some of. the annual volumes of Transactions of the Institute, and we extend our. compliments and thanks to the Committee and express to the members thereof and to. the authors, who have so bounteously given of their time and information, the. sincere gratitude of the Institute. In order to get all these papers printed and distributed to the membership in advance of the meeting, it was necessary to divide the work between two printers. This accounts for the discrepancy in the pagination of the Bulletin; and we also ask the indulgence of our readers in case errors have crept into this preliminary edition during the period of unusual pressure. Program of the Butte Meeting.-The program of the Butte meeting will include six technical sessions for the presentation and discussion of papers and five half-clay visits to mines and metallurgical works. The following program is practically in final form, with slight additions which may be necessary later. Every effort will be made to have papers presented and discussed on scheduled time, so that members who are unable to attend the entire meeting may so plan their trip as to hear and discuss papers in which they are especially interested.

Jan 8, 1913

Where Does the Mine Dollar Go? BY PAUL M TYLER (Min & Met, April, 183 3900 words) Wage earners on the job get nearly 50 per cent of the mine dollar; salaries normally take over 5 per cent (less for large metal mines); and less than 20 per cent is expended for supplies, materials, fuel, and power The total of all such specified expenditures, which may be loosely described as "direct costs," has tended over several decades to decline from over 75 per cent to under 70 per cent of the gross receipts from the sale of products of mines and quarries The item of supplies and material is far less important in the extractive industries (mines, forests, and fisheries) than in manufacturing For manufactured products the average cost of raw materials was 30 4 per cent of gross sales, almost double the proportion for the mineral industries, whereas factory wages and salaries accounted for only 33 2 per cent instead of 51 9 per cent Within reasonable limits, the margin above direct costs as herein calculated affords a measure of capital&apos;s share in the total realized from sales A preponderant group of mineral industries operate under conditions that permit or require a margin of 25 to 45 per cent At one end of the scale are highly organized industries such as sulfur, fuller&apos;s earth and iron ore mining employing much

Jan 1, 1935