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ASIDE from the John Fritz Medal, in which the Institute participates through its representation on the John Fritz Medal Board, the Institute itself has five major awards to make annually for excellence in technical papers, as follows: The Robert W. Hunt Medal, The Hadfield Prize, The J. E. Johnson Jr., Award, The Lewisohn Platinum Prize to senior members, and the President's Prize to junior members. ROBERT W. HUNT MEDAL The partners of Robert W. Hunt established a fund which was presented to the Institute at a fitting ceremony on May 27, 1920, to establish an annual medal and a sum of money to be awarded under the following rules: 1. The award shall consist of two prizes; first of a gold medal, second of a sum of money; a certificate to accompany each prize. The money prize shall not be awarded to. a member over 40 years of age, but under unusual circumstances, both prizes may be allotted to one person provided that he is not over 40 years of age. In general it will be understood that the Committee shall award the money prize to the younger men, rather than the medal. 2. The awards shall be made not oftener than once a year to that person or persons contributing to the Institute the best original paper or papers on iron and steel. The scope of the term "iron and steel" shall be determined by the sub-committee considering the awards. In general, papers dealing with the practical side of the subject have preference over those dealing with the theoretical side in recognition of the fact that Captain Hunt's main contributions to the industry have been in the improvement of production and quality of material. 3. A sub-committee of three to five including the Chairman of the Iron and Steel Committee, shall be appointed by the iron and Steel Committee annually to adjudge the award subject to approval. 4. The awarding committee shall submit its report to the Iron and Steel Committee at its October Meeting, and the. award be certified to the Secretary of the Institute in time to permit the presentation to be made at the Annual Meeting of the Institute. 5. The recipient of the award shall be designated "The Hunt Medallist." SIR ROBERT HADFIELD PRIZE Sir Robert Hadfield has offered an Institute prize of $1000 for researches with regard to the different forms of combination of carbon in iron and steel. Until within a few weeks no paper has been submitted which could compete for this prize. If the paper in hand should not meet the requirements, the donor has suggested that the prize be transferred and offered for: (a) the determination of the hardness in metals in connection. with super-hardness, (b) in consideration of questions of fuel economy, (c) in consideration of questions of industrial development and labor. J. E. JOHNSON, JR. AWARD This award is made from the income of a fund of $3000 donated by Mrs. Margaret Hilles Johnson in memory of her husband, J. E. Johnson, Jr., who was a prominent engineer, author of two valuable volumes on iron blast-furnace construction and practise, vice-chairman of the Institute's Iron and Steel Committee, and a frequent contributor of papers to the Institute's TRANSACTIONS.

Jan 1, 1925

Jan 1, 1958

By H. H. Klepfer, M. E. Snyder

UNTIL very recently, the commercial availability of the rare earths as metals has been very limited. Fabrication of mill products from these metals has not been studied in most cases. This note reports the results of the development of fabrication techniques for thulium. Thulium has a melting point of about 1550°C and a hexagonal close-packed crystal structure. It oxidizes in air to give a black oxide (TmzO,). The procedures for producing thin thulium foil were developed on one ingot weighing about 220 g and were subsequently applied in processing about a pound of metal to foil. Several alternates for the various fabrication steps were investigated and will be discussed. The metal fabricated was in the form of commercial chill-cast ingots 1 in. in diam and 2 in. long weighing approximately 220 g. Impurities in the ingots were reported by the vendor to be 4000 ppni tantalum, 2000 ppm calcium, 200 ppm nickel, 100 to 200 ppm iron, 100 ppm europium, and less than 100 ppm copper, lutetium, and ytterbium. In addition to these impurities, several salt-like inclusions as large as l/8 in. in diam were revealed along the center line of the one ingot sectioned. Preliminary tests indicated that small wafers cut from the as-cast ingot would not fabricate readily by rolling. Forging of copper-jacketed wafers was therefore attempted. At 1550"F forging was satisfactory but an apparent reaction of copper with thulium demanded investigation of lower temperatures. Therefore, the remainder of the test ingot was forged at 1450°F—with only minor cracking. All ingots forged were inserted into copper tubes of 1 in. 1D and 0.125-in. wall thickness. The jackets were sealed by flattening the ends of the tubes and welding under helium. Heating time at 1450°F was 30 min. Press forgings of 1/8 in. per pass were used, followed by 10 min reheats. When the ingots had been squared and reduced to 0.250 in. in thickness, the original copper jacket was stripped off and replaced by a new jacket in preparation for hot rolling. Hot rolling at 1450" F without edge cracking was readily accomplished after forging. Excellent results were obtained with 10 pct reductions of thickness followed by 5 to 10 min reheats. After reduction of thickness from 0.250 to 0.100 in. the copper jacket was removed. It was found, in fact, that hot rolling in air was possible. A tenacious black oxide similar to that seen on zirconium was formed during 3 min reheats at 1450°F. Reduction in air to 0.010 in. foil was possible taking 10 pct reductions per pass. The oxide coat formed during hot rolling in air could best be removed by sand blasting and pickling. Common pickling solutions containing polar solvents were found to attack the metal too rapidly and a concentrated nitric-hydrofluoric acid mixture attacked neither the oxide nor the metal. The most satisfactory pickling solution was 52 vol pct concentrated nitric acid-48 vol pct glacial acetic acid. After forging to 0.250 in., vacuum annealing and cold rolling was found to be another satisfactory alternate to hot rolling in copper jackets. After forging. a hardness of Rockwell B76 was found. Annealing in vacuum (2 X l0-5 mm of Hg) for 1 hr at 1200"F did not alter this value. Annealing at 1470"F for 1 hr brought the hardness down to R;]63. With cold rolling (5 pct per pass) the hardness returned to about R,1:76 after 20 pct reduction and edge cracking became noticeable. However, cold rolling to a total of 40 pct reduction in thickness (RI,,83) was possible before edge crack propagation became serious. Good surface finish was obtained, and the metal loss due to oxidation was minimized by cold rolling and vacuum annealing. Using this procedure the yield of 1.25 in. wide by 0.010 in. thick foil from a 1-in. diam ingot was about 40 pct.

Jan 1, 1961

The negative charges on diaphragms of quartz, tungstic oxides, stannic acid, acid dyestuffs, soaps, and glass have for a number of years been explained on the basis of chemical equilibria—a hydrogen ion or light metal ion passes into solution leaving the solid complex ion negatively charged. While there are a number of observations which indicate a proportionality between the ( potential and the streaming potential it should be recognized that all the experimental evidence thus far presented shows that if hydrogen ion concentration is kept at a constant value, electrokinetic phenomena are influenced by salts. The multivalent ions exert the greatest effect on the reduction of osmotic flow. In the interpretation of all electrokinetic data the assumption is made that the potential of the solid remains constant. That this is not true is evidenced by the values of [ potential for quartz in contact with conductivity water as reported by the several investigators and by the authors of this paper. It is apparent that the nonreproducibility of surfaces will always prevent the obtaining of exactly comparable data. At best the experimental technique described depends on a theory which is capable only of showing a trend—another quartz surface should exhibit similar but not identical potential curves. It seems entirely reasonable to assume that the negatively charged laurate ions should have little or no attraction for a negatively charged quartz surface. The weight of previous experience in selection of flotation activators points unerringly to the usefulness of the multivalent metallic ions. The primary reason why the divalent barium ion is not available to two negative charges on the quartz surface might easily be that of distance between such adjacent negative charges. Otherwise activation could not occur, and the quartz could not assume the remaining unit positive charge of the barium ion. For this case no electrical double layer theory seems necessary. Clearly this is, at the negatively charged quartz surface, a case of partial chemisorption of the cationically divalent barium ion followed by the anionic neutralization of the remaining cationic charge by the freely moving laurate ion. It is hoped that the authors will continue with this interesting technique and that their results will continue to indicate trendwise what is known about the

Jan 1, 1957

By Casper A. Nelson, Wendell M. Whitecotton

A WIDE variety of lead ore is treated by the Midvale Smelter, for it is a custom plant not only treating Company lead concentrate and direct-smelting ores but also custom ores and concentrates, principally from Utah, Idaho, and Nevada, with lesser amounts from Arizona, California, Colorado, Montana, Oregon, and Washington. The principal operating departments of the plant are weighing and sampling, Wedge roaster, D&L sintering, blast furnace and drossing, and baghouse. The lead bullion produced is shipped to a subsidiary, the U.S.S. Lead Refinery, Inc., at East Chicago, while the by-products, such as matte and speiss, are shipped to other smelters or re-treated at the plant.

Jan 1, 1948

By B. F. Buie

Included in the general category of clays is a large and varied assemblage of nonmetallic silicate minerals which characteristically occur as fine-grained particles having flaky, sheetlike, or rod-shaped form. Most, though not all, are hydrous aluminum silicates. Amount and kind of impurities vary greatly, and these strongly influence the uses of the various clay types. Clays occur in a wide range of geological situations: as bedded sedimentary deposits composed of the weathering products of feldspar and other minerals; as alteration products of igneous, sedimentary, and metamorphic rocks weathered or hydrothermally altered in place; and, to a more limited extent, as hydrothermally introduced materials. TYPES AND MARKETS On the basis of chemical composition and crystal structure, two major groups of clay minerals recognized are the "kandites" or kaolin group, and the "smectites" or montmorillonite group. Another major type is illite, particularly important as a constituent of shales. Two additional mineral species having economic importance are attapulgite (palygorskite) and sepiolite. For present purposes, however, a classification based on utilization is more appropriate. The U.S. Bureau of Mines recognizes six types of clay: kaolin, ball clay, fire clay, bentonite, fuller's earth, and miscellaneous clay. Kaolin The kaolin group of minerals consists of the mineral species kaolinite, halloysite (metahalloysite), dickite, and nacrite, although the latter two are not being produced commercially. Kaolin, also called china clay, is a high-purity white material. Perhaps it is best known as a principal ingredient in the manufacture of chinaware, porcelain, and other high-quality ceramic products. However, by the mid-1970s very close to 50% of the kaolin produced in the United States was going to the paper industry for use as a filler and coating material. Manufacture of refractories uses about 12% of U.S. production. Kaolin is also used in plastics, in the rubber industry as a filler in footwear, electrical cable, and similar products, and as a conditioner of rubber for automobile tires to add strength and abrasion resistance. Smaller amounts are used in printing ink, paint, and adhesives; as insecticide carriers; in the production of catalysts for the petroleum refining industry; and in many other industrial and commercial applications. Production and use of kaolin in the United States doubled in the ten years from 1946 to 1956, and doubled again by 1966. Growth continues at a rate of about 7 % per annum.

Jan 1, 1976

By H. K. Shearer

Oil production in north Louisiana in 1938 was 28,442,910 bbl., a decrease of 225,160 bbl., or less than 1 per cent, from 1937. The principal increases were at Cotton Valley, Lisbon and Zwolle. The greatest decrease was at Rodessa, with small normal declines in production of the old settled fields. Natural gas production from gas wells declined 15.9 per cent from 1937, but casinghead gas increased, so the decline in total production was only 6.9 per cent. Decline in completions was due to lack of proven areas for drilling, as well as price and marketing difficulties; and wildcat activity mas also less than in 1937. The increase in number of dry holes was due chiefly to shallow drilling in the old Caddo and Zwolle fields. Most important events in 1938 were the discovery of the Shreveport deep oil and gas field, extension of the Logansport gas-distillate field into Louisiana, development of oil production in the Bodeaw zone on the flanks of Cotton Valley, opening of deep gas-distillate production at Shongaloo, and completion of one well in a deeper horizon at Bluc Lake (Zwolle field). Geological Notes The deep drilling done in 1938 did not cause any important changes in geological correlation and nomenclature of the formations below the Upper or Gulf Cretaceous. The stratigraphic section of the Lower Cretaceous and deeper beds, with names used in the accompanying tables, as approved a year ago by the Shreveport Geological Society, is as follows:

Jan 1, 1939

By Henry Gross

RECENTLY, areas of abnormal rock pressure have been drilled on the Gulf Coast of the United States. These pressures may be caused by the recent and pronounced raising of some of the structures without loss of the formation pressure that existed when the reservoir was developing and the producing sand much more deeply buried. It is possible also that a permeable fissure may connect a shallow accumulation of gas with the gas cap of a much deeper reservoir of oil, gas and water. The pressures are so great that dependence on blowout-prevention equipment alone is hazardous to life and property. Fortunately, wells with excessive casing-head pressures, such as the Stanolind Oates No. 1 of the South Houston field, an 8700-ft. gas well with 6000 lb. per sq. in., and the near-by Stanolind Candelari No. 1, and 8100-ft. gas well with 5000 lb. per sq. in., have not blown out and cratered. A case is on record of drill pipe in a, well in Harris County, Texas, (Oates No. 1) rotating for 8 hr. through blowout-prevention rants holding a back pressure of 2900 1b. per sq. in. at the casinghead after the mud was altered by salt-water intrusion. Such conditions warrant the use of extremely heavy muds having low viscosity, made from galena (PbS) or specially prepared mixtures of hematite (Fe203) and galena suspended by bentonite. In some Gulf Coast wells, sodium silicate mixed with concentrated brine is used to drill through heaving shale formations. Such a fluid inhibits heaving remarkably, but it is expensive and costs as much as $10 per barrel. Barite has been used to weight this mixture. However, this mineral too rapidly increased an already excessive viscosity and it was thought that galena might be better for weighting such drilling fluid. The operator was anxious to try the latter, but none was available in the district.

Jan 1, 1938

By G. H. Fancher

Improving economic conditions are reflected in the statistical picture of the petroleum and natural gas industry for 1933. Prices were better, demand was greater and the volume of production increased. The increase in the production of gas has been due mainly to the utilization of outlets to the new prolific gas fields of Potter and Tioga counties; of oil, to the growing demand for Pennsylvania grade lubricants. It should be emphasized that nowhere is volume of production more subject to control due to the extensive use of secondary methods of recovery and regional peculiarities than in Pennsylvania. A summary of developments in production for Pennsylvania in 1933 of necessity is brief. The data listed in Table 1 are all too few in number and not all that is desirable from the standpoint of accuracy. No state agency for the collection of data exists, no reports are compulsory. Nevertheless, because of the hearty cooperation of many individuals and public spirited corporations, it is believed that the data are as reliable as are obtainable at the present time. Furthermore, records of the past too often are lost, were never in existence or are fragmentary, to say the least. Illustrative of the condition is the fact that no thorough study of the oil and gas-producing regions has ever been made. The publications of the Pennsylvania Topographic and Geologic Survey upon the subject are noteworthy and valuable, especially the most recent one.' The Survey has been handicapped in the work by lack of time, personnel and funds in addition to the difficulties mentioned previously. It is obvious, therefore, that Table 1 cannot be completed for Pennsylvania. The data simply are not in existence. Officially there are 328 oil and gas pools or fields known by name and 58 distinct sands or horizons, one or more of which are productive of oil and gas in the various pools, but reliable data for only three general regions could be assembled.

Jan 1, 1934

By H. K. Shearer

Oil production in north Louisiana in 1938 was 28,442,910 bbl., a decrease of 225,160 bbl., or less than 1 per cent, from 1937. The principal increases were at Cotton Valley, Lisbon and Zwolle. The greatest decrease was at Rodessa, with small normal declines in production of the old settled fields. Natural gas production from gas wells declined 15.9 per cent from 1937, but casinghead gas increased, so the decline in total production was only 6.9 per cent. Decline in completions was due to lack of proven areas for drilling, as well as price and marketing difficulties; and wildcat activity mas also less than in 1937. The increase in number of dry holes was due chiefly to shallow drilling in the old Caddo and Zwolle fields. Most important events in 1938 were the discovery of the Shreveport deep oil and gas field, extension of the Logansport gas-distillate field into Louisiana, development of oil production in the Bodeaw zone on the flanks of Cotton Valley, opening of deep gas-distillate production at Shongaloo, and completion of one well in a deeper horizon at Bluc Lake (Zwolle field). Geological Notes The deep drilling done in 1938 did not cause any important changes in geological correlation and nomenclature of the formations below the Upper or Gulf Cretaceous. The stratigraphic section of the Lower Cretaceous and deeper beds, with names used in the accompanying tables, as approved a year ago by the Shreveport Geological Society, is as follows:

Jan 1, 1939

By John V. Beall

Cutting costs and increasing safety with new ideas is the byword with The Cleveland-Cliffs Iron Co. on the Marquette Range in Michigan. Among the new ideas being tried out are mechanical shaft mucking, prefabricated lagging to replace timber poles, Carset bits in shaft sinking, and rubber tired guide wheels on the ore skips. Plans are being made to stockpile ore with conveyor belts during the winter. In sinking the Mather "B" Shaft a 3/8-yd clamshell-type bucket is used for mucking. The clamshell is opened and closed by means of a verticallymounted hydraulic ram actuated by 5000 psi oil pressure. An Ingersoll Rand-type hoist is used to raise and lower the clamshell. The hoist is controlled by one member of the crew on the floor of the shaft. When the bucket is raised, the men swing it over the muck pile to the desired position and then it is lowered on to the broken rock. The 1400-lb weight of the bucket causes it to sink into the broken rock and it digs as the ram closes the bucket. The hydraulic ram is operated by a man on the lowest shaft steel set who controls a specially designed oil pump which supplies oil pressure. The clamshell is emptied.

Jan 1, 1949

The Institute conducts jointly with the American Society of Civil Engineers, American Society of Mechanical Engineers and American Institute of Electrical Engineers, certain activities as listed below, and is joint owner with them of certain properties. United Engineering Trustees, Inc. When Mr. Carnegie made. his gift ?for the erection of a suitable home? for the engineering societies,

Jan 1, 1944

By F. S. McNicholas

Various methods of block caving and draw practice are classified and the advantages, disadvantages, rock, treatment, size of orebody, costs, and profit comparisons, and other factors which determine the selection of the proper method are outlined.

Jan 1, 1951

By P. A. Beck, Hsun Hu

As described by means of quantitative pole figures, the annealing texture of highly rolled aluminum consists of the four retained components of the rolling texture near (123) [121], rather more sharply developed, and of a cube texture component. Local reorientation corresponds fairly well to 40 rotation around a [111] axis. In copper strip rolled 96 pct, the annealing texture is mainly the cube texture, with the four twin orientations as minor components. The annealing texture of highly rolled brass strip consists of four components of the (225) [734] type. REVIEWS by Wassermann,' Barrett,' Dunn,3 and Richards' give detailed accounts of the numerous publications dealing with annealing textures in rolled polycrystalline metals. Although a considerable amount of information of an empirical nature has been available for many years, even relatively recently the state of recrystallization-texture theory was considered uncertain. The reviews referred to above deal mainly with the description of experimental results, without developing generally applicable principles, suitable for explaining the observed annealing textures. The investigations of Burgers and Louwerse5 and Barrett6 showed that in deformed single crystals of aluminum the orientation of the recrystallized grains deviates drastically from that of the deformed matrix. According to Barrett and to Beck and Hu,7 the relationship between the two orientations can be best described as a rotation of about 40° around a [111] axis. Recent investigations led to similar orientation relationships for various face-centered cubic metals with a simple texture, regardless of whether the annealing process was recrystallization (strain-free grains growing in a highly deformed large crystal of aluminum' or copper: or in deformed cube texture copper") or coarsening (strain-free grains growing at the expense of an essentially strain-free, fine grained, polycrystalline matrix of single orientation texture copper,'" aluminum,' or nickel-iron). Barrett" pointed out the possibility that this orientation relationship may be a result of the orientation dependence of the rate of grain boundary migration. More recently, considerable evidence became available in favor of this view.12,13 In apparent contradiction to the above results, it has been known for a long time that the recrystallization texture of polycrystalline metals is often similar to the deformation texture. This was found, in particular, for the fiber textures obtained by wire drawing, compression, or compression rolling.' Following a suggestion by Barrett,2 Kronberg and Wilson and Beck and Hu7 described a mechanism by which a [Ill] fiber texture, resulting from plastic deformation, may be retained upon recrystallization, even though the orientation of individual recrystallized grains differs from that of the local area of the matrix in which they grow. This mechanism assumes that the reorientation corresponds to a rotation around the [1ll] axis, which is also the fiber axis. The present investigation was undertaken to examine in detail the orientation relationship between deformation texture and recrystallization texture in rolled face-centered cubic metals, using the quantitative methods of texture determination that have recently become available.", '" Quantitative pole figures for the rolling textures of such metals were reported recently." Quantitative pole figures for annealing textures are given in the present paper. It was planned to investigate whether or not the orientation relationship previously found for the recrystallization of deformed single crystals, and for coarsening of single-orientation texture material, is capable of accounting for the observed, often complex, annealing textures in rolled polycrystalline metals. The question whether local reorientation is predominant, even in the early phases of the annealing process, was to be studied with high purity aluminum. by making use of an oxide film and sensitive tint illum-

Jan 1, 1953

By John L. Boardman

BECAUSE of the attention that has re¬cently been given to the health and safety of miners by various organizations such as the A.I.M.E., The American Congress, Mining Section, National Safety Council, as well as the Bureau of Mines and various state mining departments, your committee on health and safety deemed it best to call attention this year to the mine-accident cause that is by far the most important; namely, injuries due to falls of ground, rock, roof and coal. Each of several members of the committee contributed a brief outline of the importance of this accident cause in his district. While these papers were brief, it would require too much time and space to give them in full, therefore we present an outline of each and summation of all. REPORT OF M. D. COOPER, HILLMAN COAL AND COKE CO. M. D. Cooper, Division superintendent, Hillman Coal and Coke Co., Pittsburgh, Pa., contributed the following: During the period from 1930 to 1939, accidents from falls of roof in bituminous mines average 54.3 per cent of all accidents. In mechanized mining, there is a tendency toward reduction in this class of accidents because the operator of the machine is usually at a distance of 10 to 20 ft. from the face, whereas. in hand loading the miner is close to the face during most of the shift. No doubt the use of aluminum and light steel beams supported at regular intervals by jacks, a common practice in mechanical mining, has contributed to the favorable record so far developed. REPORT OF M. H. FIES, DE BARDELEBEN COAL CORPORATION Milton H. Fies, Vice-President, DeBardeleben Coal Corporation, Birmingham, Ala., says: With reference to the types of mining, it is suggested that a clear understanding be had as to the character and thickness of the directly overlying strata, with especial consideration to the strength and in some cases an analysis of it. In coal mining, generally speaking, overlying strata higher in silica than others is stronger. In changing from narrow to wide places, the procedure should be experimental, both as to the width and depth of places and as to the nature of the necessary timbering. Since most of the accidents in coal mining particularly are due to falls of roof and coal, this phase of mining should be attacked with vigor. There is no substitute for discipline and, in this connection, under present conditions it is important that cooperation by the labor organizations be sought and that a spirit of fairness prevail. Frequent and thorough inspection of all active working places should be made.

Jan 1, 1941

By John L. Boardman

BECAUSE of the attention that has recently been given to the health and safety of miners by various organizations such as the A.I.M.E., The American Congress, Mining Section, National Safety Council, as well as the Bureau of Mines and various state mining departments, your committee on health and safety deemed it best to call attention this year to the mine-accident cause that is by far the most important; namely, injuries due to falls of ground, rock, roof and coal. Each of several members of the committee contributed a brief outline of the importance of this accident cause in his district. While these papers were brief, it would require too much time and space to give them in full, therefore we present an outline of each and summation of all. REPORT OF M. D. COOPER, HILLMAN COAL AND COKE CO. M. D. Cooper, Division superintendent, Hillman Coal and Coke Co., Pittsburgh, Pa., contributed the following: During the period from 1930 to 1939. accidents from falls of roof in bituminous mines average 54.3 per cent of all accidents. In mechanized mining, there is a tendency toward reduction in this class of accidents because the operator of the machine is usually at a distance of 10 to 20 ft. from the face, whereas in hand loading the miner is close to the face during most of the shift. No doubt the use of aluminum and light steel beams supported at regular intervals by jacks, a common practice in mechanical mining, has contributed to the favorable record so far developed. REPORT OF M. H. FIES, DE BARDELEBEN COAL CORPORATION Milton H. Fies, Vice-President, DeBardeleben Coal Corporation, Birmingham, Ala., says: With reference to the types of mining, it is suggested that a clear understanding be had as to the character and thickness of the directly overlying strata, with especial consideration to the strength and in some cases an analysis of it. In coal mining, generally speaking, overlying strata higher in silica than others is stronger. In changing from narrow to wide places, the procedure should be experimental, both as to the width and depth of places and as to the nature of the necessary timbering. Since most of the accidents in coal mining particularly are due to falls of roof and coal, this phase of mining should be attacked with vigor There is no substitute for discipline and, in this connection, under present conditions it is important that cooperation by the labor organizations be sought and that a spirit of fairness prevail. Frequent and thorough inspection of all active working places should be made.

Jan 1, 1941

Discussion of the paper of GEORGE S. Rice, presented. at the Pittsburgh meeting, October, 1914, and printed in Bulletin No. 94, October, 1914, pp. 2459 to 2492. WILLIAM GRIFFITH, Scranton, Pa.-I notice in the discussions and literature that emphasis is placed on rock dust, shale dust, and limestone dust, and I infer that these different. sorts of rock are ground up to produce this dust. -Is that right? MR. RICE.-That is correct, but we do not have to grind the limestone dust we are using in the experimental mine, as that is obtained from a quarry, and is used just as it comes; we can get it very cheaply, as it is a by-product of the quarries. MR. GRIFFITH.-Have any experiments been made with ordinary dirt out of the fields; could not that be used as ground dust? MR. RICE.-If you dry it and powder it enough so it will float in a, strong air current it might be all right for the barriers, but if it is damp there will be a tendency for it to mat together; then it would be quite useless for making a dust cloud. There might also be another disadvantage if used through the whole mine, if it had very much free silica in it, which is bad for the lungs. Limestone and selected shale dust would not affect the health of miners. MR. GRIFFITH.-In order to do very much good with any of those barriers, they ought to be rather extensively used throughout the mines, and there are few mines that have facilities for grinding up this rock into such a fine dust. If the ordinary earth from a plowed field could be used, even if it were not quite so good, it is more accessible and very much cheaper; therefore, in using it, with the universality of the supply through-out the country, it would tend to stop explosions. MR. RICE (communication to the Secretary*).-In closing, it is well to again emphasize that I do not advocate barriers being a "cure-all" for explosions. It will be generally agreed that prevention is best, not only by means of improved methods of using explosives, and ventilation to prevent accumulations of firedamp, but also by either thoroughly wetting the dust throughout the mine, or else so treating it with rock dust or other inert dust that an explosion cannot start. From my observations I believe that rock dusting. is a practicable method, and has the merit of visibility, and remaining effective for considerable periods, whereas the watering method has to be daily followed up, and if neglected for a short period the mine may become in a dangerous condition. The Germans

Jan 4, 1915

By I. Fatt

Networks of resistors are used as analog computers to obtain relative permeability and resistivity index curves for networks of tubes. These curves have all of the characteristics of those obtained on porous media and, therefore demonstrate the validity of the network of tubes model. INTRODUCTION In paper I' of this series the network model was shown to give information on the structure of porous media that could not be obtained from the bundle of tubes model. The agreement between the capillary pressure characteristics of a network of tubes and those of typical porous media does not prove the validity of the network made. The bundle of tubes model, although it gives less information, also shows this agreement. In this paper the flow properties of a network of tubes are shown to be in agreement with flow properties of porous media. The flow properties of the bundle of tubes model are not in adequate agreement with those of porous media. The dynamic properties of porous media, such as fluid permeability and electrical conductivity, have been found experimentally to be more sensitive functions of structure and pore size distribution than are the static properties such as porosity and capillary pressure characteristics. The network model can, therefore, be best tested by comparing the dynamic properties of a network of tubes with the observed properties of porous media. All static and dynamic properties of a completely valid model must agree with the observed properties. The most commonly measured sensitive dynamic properties are the relative fluid permeability and the relative electrical resistivity. Experimental measurements of these dynamic properties on sandstone, sintered glass, sintered alumina, and soil are reported in the petroleum and soil science literature. These properties were chosen, therefore, for the test of the network model. In the network model, relative permeability is the permeability of the network when some of the tubes are not conducting fluid, relative to the permeability when all tubes are conducting fluid. Similarly, the relative resistivity is the electrical resistivity of the network of tubes when some of the tubes are filled with a nonconductor. relative to the resistivity when all tubes are filled with the electrical conducting fluid. Single Size Tube Network The simplest porous medium is one in which all pores are of the same size. Such media can be approached by packing beds or columns of uniform size particles of sand, glass, or metal. The model of such medium in this study is a network of single size tubes. The network form, the ß factor, is usually not known for real porous media. If the validity of the network model can be established, then the study of the flow properties

Jan 1, 1957

By Glenn S. Wyman

CHUQUICAMATA, located in northern Chile in the Province of Antofagasta, is on the western slope of the Andes at an elevation of 9500 ft. Because of its position on the eastern edge of the Atacama Desert, the climate is extremely arid with practically no precipitation, either rain or snow. All primary blasting in the open-pit mine at Chuquicamata is done by the churn drill, blasthole method. Since 1915; when the first tonnages of importance were removed from the open pit, there have been many changes in the blasting practice, but no clear-cut rules of method and procedure have been devised for application to the mine as a whole. One general fact stands out: both the ore and waste rock at Chuquicamata are difficult to break satisfactorily for the most efficient operation of power shovels. Numerous experiments have been made in an effort to improve the breakage and thereby increase the shovel efficiency. Holes of different diameter have been drilled, the length of toe and spacing of holes have been varied, and several types of explosives have been used. Early blasting was done by the tunnel method. The banks were high, generally 30 m, requiring the use of large charges of black powder, detonated by electric blasting caps: Large tonnages were broken at comparatively low cost, but the method left such a large proportion of oversize material for secondary blasting that satisfactory shovel operation was practically impossible: Railroad-type steam and electric shovels then in service proved unequal to the task of efficiently handling the large proportion of oversize material produced. The clean-up of high banks proved to be dangerous and expensive as large quantities of explosive were consumed in dressing these banks, and from time to time the shovels were damaged by rock slides. As early as 1923 the high benches were divided, and a standard height of 12 m was selected for the development of new benches. The recently acquired Bucyrus-Erie 550-B shovel, with its greater radius of operation compared to the Bucyrus-Erie 320-B formerly used for bench development, allowed the bench height to be increased to 16 m. Churn drill, blasthole shooting proved to be successful, and tunnel blasts were limited to certain locations where development existed or natural ground conditions made the method more attractive than the use of churn-drill holes. Liquid oxygen explosive and black powder were used along with dynamite of various grades in blasthole loading up to early 1937. Liquid oxygen and black powder were discontinued because they were more difficult to handle due to their sensitivity to fire or sparks in the extremely dry climate. At present ammonium nitrate dynamite is favored because of its superior handling qualities and its adaptability to the dry condition found in 90 pct of the mine. In wet holes, which are found only in the lowest bench of the pit and account for the remaining 10 pct of the ground to be broken, Nitramon in 8x24-in. cans, or ammonium nitrate dynamite packed in 8x24-in. paper cartridges, is being used. This latter explosive, which is protected by a special antiwetting agent that makes the cartridges resistant to water for about 24 hr, currently is considered the best available for the work and is preferred over Nitramon. Early churn drill hole shots detonated' by electric blasting caps, one in each hole, gave trouble because of misfires caused by the improper balance of resistance in the electrical circuits. Primarily, it was of vital importance to effect an absolute balance of resistance in these circuits, the undertaking and completion of which invariably caused delays in the shooting schedule. Misfires resulting from the improper balance of electrical circuits, or from any other cause, were extremely hazardous, since holes had to be unloaded or fired by the insertion of another detonator. The advent of cordeau, later followed by primacord, corrected this particular difficulty and therefore reduced the possibility of missed holes. After much experimentation, the blasting practice evolved into single row, multihole shots, with the holes spaced 4.5 to 5 m center to center in a row 7.5 to 8 m back from the toe. Such shots were fired from either end .by electric blasting caps attached to the main trunk lines of cordeau or primacord. The detonating speed of cordeau or primacord gave the practical effect of firing all holes instantaneously. Double row and multirow blasts, fired instantaneously with cordeau or primacord, proved to be unsatisfactory in the type of rock found at Chuquica-

Jan 1, 1952

By J. N. Butler, R. J. Morris

A series of organic collectors has been developed which successfully float synthetic secondary uranium minerals, such as autunite, carnotite, and torbernite. Recoveries up to 97 pct have been obtained. With cleaning of rougher concentrates, ratios of concentration as high as 15:1 are possible on head assays of 0.10 to 0.50 pct U 3 O 8. Additions of certain base metal salts aid in recovery and materially increase the rate of flotation and selectivity of the collectors for the synthetic minerals. Flotation tests on natural uranium minerals have not yet equaled results obtained on the synthetics, although these collectors do give better results than conventional collectors for nonsulfide minerals. RAPID increase in mining and milling uranium ores during the past seven years and the discovery of large tonnages of uranium-bearing material too low in grade to stand the cost of leaching have developed considerable interest in possible methods for beneficiating these marginal ores. Such ores are generally classed as those containing less than 0.10 pct U3O8. Development of a beneficiation method that would give both high recovery and high ratio of concentration would also make possible the beneficiation of higher grade ores and would provide higher grades of feed to existing leaching plants. Although considerable research and testing on physical or physico-chemical beneficiation of domestic uranium ores has been done in the past, to the best knowledge of the authors only a single application of physical beneficiation is now in operation on a commercial scale. Flotation has been attempted on the basis of mineral association rather than by direct concentration of the contained uranium minerals. Flotation studies conducted on this project on certain ores gave recoveries of 60 to 70 pct of the uranium by the use of conventional flotation agents such as oleic acid, but ratios of concentration were in the order of 1.5:1 to 2.5:1. Subsequent cleaning to upgrade the concentrates rapidly increased losses in the cleaner tailings, which were not later refloated in the rougher flotation. Selection of Collector: In selecting desirable organic collectors for these oxide systems, a thorough study was made of the relationship between structural characteristics and collector activity by an examination of the behavior of a number of different functional arrangements present in a variety of organic molecules, (see Fig. 1). It is generally accepted that a collector must have a relatively long-chain hydrocarbon radical and a chemically reactive elec-trophilic center. Such a requirement could be met by a large number of compounds, but steric effects at the uranium mineral surface, solubility, compat-ability with aqueous systems, air avidity, bond strength at the mineral surface, interfacial concentration of the collector, and diffusion rate of the formed complex from the air-water interface eliminated many as unsuitable for this purpose. Preliminary investigations were completed of possible collector designs consisting of aliphatic and aromatic hydrocarbon radicals attached to stable combinations of nitrogen, oxygen, sulfur, and halogen electrophilic centers, Fig. 1.Tests were made to determine melting point spans, solubility of mineral-collector combinations in various solvents, reactions with soluble uranium salts, contact angles, and floatability by semi-quantitative beaker methods.' Contact angle determinations were not too useful because of the fine particle sizes of available mineral samples. From the foregoing study it appeared that nitrogen-sulfur electrophilic centers coupled with straight-chain saturated alkyl hydrocarbon radicals would hold the most promise for floating secondary uranium minerals. As the dithiocarbamate compounds can be made to combine these attributes they were selected for further study. The dithiocarbamates form a parallel structure to the xanthates, with the fortuitous exchange of

Jan 1, 1957