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By R. R. Kimpel, L. G. Austin

An equation is derived describing fragment size for single fracture of brittle solids. It contains the equations of earlier workers as special or approximate cases and, in addition, is capable of describing coarse distributions in which a few large particles are produced on fracture. The equation can be fitted well to single fracture experiments where over-breakage is avoided. In 1956 Broadbent and callcottl described a method of analyzing the unit operation of grinding, applicable to homogeneous breakage of brittle materials. In essence, the grinding process was split into two parts: 1) the fractional amount of a given size which is selected for grinding per unit time, 2) the size-weight distribution of the fragments produced by breakage of this certain size (primary breakage distribution function). The theory was formulated using matrix algebra. They attempted an experimental verification of the theory using an assumed primary breakage distribution but the results were not very satisfactory. Austin and Gardner2 showed that this assumed distribution was widely different from experimental values and that it led to the poor agreement of predicted size-weight distributions with experiment found by Broadbent and Callcott. In addition, Austin and Gardner2,3,4 reformulated the original approach in terms of differential equations of grinding and demonstrated that the approach led to a very satisfactory description of the grinding process, providing that the descriptive parameters were measured experimentally. Recent work5 has substantiated these findings and the distribution functions of several materials ground under different conditions in different mills have been determined experimentally. The fraction underweight versus size used by

Jan 1, 1965

By H. J. Rose

Graphic methods have long been used to advantage in dealing with diverse phases of fuel technology and research. Not only are graphs convenient for presenting data and making calculations, but they are invaluable for deriving generalizations from a mass of data. This is particularly true when relationships are obscure and numerical correlation is poor. This paper describes a new form of graph, the Multibasic Coal Chart, which has been developed to facilitate the study and comparison of coals of all ranks from peat to anthracite on any moisture and purity basis. This type of chart is of unique value for coal classification purposes, since it permits a direct visual comparison of the results obtained when coals are classified by the various systems which have been proposed. Coals are highly variable in character as a result of wide differenees in original vegetal ingredients, degree of metamorphism, and nature and amount of associated impurities. For nearly 100 years, attempts have been made to devise a satisfactory method of classification, and many tables, formulas, ratios and graphs have been suggested. Many of the suggested systems possess considerable merit and have found a limited use, thus promoting a better understanding of coal. However, objections have been raised against each system, and none has received general adoption. When the various systems of classification are compared, it is found that there is an apparently almost hopeless confusion due to: 1. Serious lack of agreement as to the proper moisture and purity basis on which to classify coal. More than ten different bases have been proposed, each of which requires complete recalculat.ion of the analysis data used. 2. Lack of agreement as to what chemical and physical properties are most important and best to use for classification purposes. There is too little knowledge of the degree to which these properties can be correlated.

Jan 1, 1930

By Fred C., Fred C. Bond

Comminution energy is principally energy of deformation before breakage, which appears as heat. An empirical equation is presented which covers the entire comminution range. The new strain-energy theory considers comminution from the known principles of mechanics and the reduction ratio. Energy requirements according to the different theories are compared.

Jan 1, 1950

By S. A. Falconer

Much attention and publicity has been given, during recent years, to grinding, classification, flotation, and thickening. The various technical papers, and symposiums held to discuss these important phases of milling, have contributed to a better under- standing of the fundamental principles and operating variables involved. Another important part of milling- to the flotation operator-is a treatment step to which frequently too little attention is given-" conditioning," or the treatment the ground mineral pulp receives before it enters the flotation machines. Conditioning" is a hackneyed and frequently misused term, commonly employed to describe the pretreatment of surfaces of minerals in ore pulps or mill pr6ducts prior to froth flotation. In general, such pretreatment is for the purpose of changing the flotation characteristics of these mineral surfaces to enable them to respond in some desired predetermined manner when subjected to flotation. Taggartl states that the function of conditioning is "either to insure selective collector coating of one mineral species while another species is not; or to take such steps as will compensate for departure there from."

Jan 1, 1949

By Joseph Chalmers, E. L. Rawlins, D. B. Taliaferro

PRoblems dealing with the movement or migration of fluids through porous beds have been the subject of much research. The subject is not peculiar to the production of oil and gas, as many investigators have studied the nature of this movement and its relationship to the problems of other industries. Darcyl conducted a series of experiments relating to the percolation of water through filter beds. King2 carried on an extensive series of laboratory experiments with the object of formulating some conception of the rate of movement of water through soils and sand strata in the drainage of surface water into underground channels and subsequent recovery of this water through wells drilled into the source beds for irrigation purposes. Slichter3 undertook a study of the same problem from a mathematical standpoint, and more recently Furnas4 has investigated the flow of gases through beds of broken solids with particular reference to blast-furnace operation. With specific reference to gas production, Muskat and Botset5 of the Gulf Research Laboratory undertook an experimental study to establish quantitatively the characteristics of and laws governing the flow of gases through consolidated and unconsolidated porous materials of fine texture with a view of predicting the performance of gas in an underground reservoir. There seems to be a general agreement that many of the relationships between the numerousfactors influencing the flow of fluids through porous materials are far too complicated to be attacked by analytical methods based upon a knowledge of hydrodynamics. For gases, the laws of

Jan 1, 1932

By Paul E. Melancon, Vincent C. Kelley, Dale F. Kittel

Uranium of the Grants region occurs predominantly in continental sandstones of the upper part of the Jurassic Morrison Formation, but significant lesser deposits are found in limestone of the Jurassic Todilto Formation and in black shale of the Cretaceous Dakota Formation. The deposits are disseminations that form runs ranging from a few hundred tons to several million tons. The ore consists mainly of uraninite, uraniferous carbonaceous material, coffinite, and such secondary oxidized minerals at tyuyamunite, carnotite, and uranophane. In sandstone, the ore runs were locallized by mudstone, interstitial carbonaceous material, and primary sand channel trends. In limestone, ore deposition was related to folds and fracture zones. The great bulk of production has come from the Ambrosia Lake mines in the Grants district and the Jackpile and Paguate mines in the Laguna district. The ores, which generally have been 0.20 to 0.30 per cent U3O8, are treated at mills operated by Kerr-McGee Corporation, Homestake-Sapin Partners, and The Anaconda Company, all in the Grants district. In 14·years after discovery in 1950, the deposits had yielded concentrates valued in excess of $800,000,000. Since deposition of the Jurassic host rocks, a geologic history involving tilting, faulting, erosion, changing ground-water environments, and oxidation has considerably influenced the existence and character of the deposits. It is evident that their ongm is not simple. However, a degree of agreement appears probable for a pre-Dakota age for the original ore runs, and, at Ambrosia Lake, two principal stages of ore formation, separated by Laramide faulting, are recognized. All earlier ores have been modified by Quaternary oxidation, solution, and enrichment during which time much secondary tyuyamunite, metatyuyamunite, carnotite were formed.

Jan 1, 1968

By AIME AIME

LOCAL COMMITTEES. EXECUTIVE.-W. A. Lathrop, Chairman; R. V. Norris, Secretary; S. D. Warriner, Treasurer; Irving A.. Stearns, W. J. Richards, H. S. Drinker, C. D. Simpson. GENERAL RECEPTION.-Irving A. Stearns, Chairman. Archibald, James, Jr., Pottsville. Lawall, E. H., Wilkes-Barre. Ashley, H. H., Wilkes-Barre. Lentz, W. 0., Mauch Chunk. Ayres, WV. S., Hazleton. Lewis, Albert, Bear Creek. Beard, J. T., Scranton. Loomis, W. H., Jeddo. Bridgman, J. C., Wilkes-Barre. Markle, Alvan, Hazleton. Bunting, Douglas, Wilkes-Barre. Markle, John, Jeddo. Chase, F. M., Wilkes-Barre. Neale, J. B., Minersville. Coroner, Eli T., Scranton. Norris, R. V., Wilkes-Barre. Cote, E. B., Jr., Drifton. Oliver, Paul A., Oliver's Mills. Davies, W. H., Hazleton. Owens, W. D., Pittston. Davis, H. G., Dorranceton. Pardee, 1. P., Hazleton. Dodge, W. F., Wilkes-Barre. Quin, R. A., Wilkes-Barre.

Jul 1, 1911

By J. Gurland

THE microstructure of sintered carbides consists of particles of metal carbides, such as WC and TiC, embedded in a metallic binder which is usually a cobalt—or nickel-rich solid solution. One of the important factors influencing the strength of the alloys is the degree of dispersion of the carbide particles in the binder matrix. While it is generally accepted

Jan 1, 1960

By W. M. Aubrey, P. L. Steffensen

AUTOMATIC grinding control for ball mills in closed circuit with cyclones was developed for the concentrator of the Marmoraton Mining Co., a subsidiary company of Bethlehem Steel Corp. The concentrator, located at Marmora, Ont., Canada, treats an ore that analyzes 35 to 40 pct magnetic iron. Magnetite, the recoverable iron mineral, is concentrated by fine grinding and magnetic separation. The mesh of grind obtained in the plant is not determined by the point at which liberation is sufficient to yield a satisfactory grade of concentrate, but by the physical requirements of the downstream pelletizing operation. This is considerably finer than is metallurgically necessary. The concentrator has two identical units, each consisting of a rod mill in open circuit, followed by a ball mill in closed circuit with a cyclone and two rougher magnetic separators. The cyclone was chosen as a classifier because of its high efficiency on heavy gravity, magnetically flocculated material.

Jan 1, 1957

MRS. SIDNEY J. JENNINGS, President, MRS. ARTHUR S.. DWIGHT, First Vice-President, MRS. KARL EILERS, Second Vice-President, MRS. H. W. HARDINGE, Third Vice-President, MRS. BRADLEY STOUGHTON, Recording Secretary, MRS. AXEL 0. IHLSENG, Corresponding Secretary, MRS. ARTHUR S. DWIGHT, Acting Treasurer. Welfare Committee MRS. C. C. BURGER, Chairman, Sub-Committees Americanization Belgian Relief MRS. LEVI HOLBROOK, Chairman, MRS. HENRY H: KNOX, Chairman, Emergency MRS. HERMAN A. PROSSER, Chairman. Since the annual meeting held in February, 1917, when the Woman's Auxiliary to the A. I. M. E., was formed, the work of organization, which of necessity must be slow, has steadily gone forward. Under the Chairmanship of Mrs. C. C. Burger of the Welfare Committee, three active sub-committees have been formed: that of Americanization; under Mrs. Levi Holbrook, who is eminently fitted for such a position, by her active and valuable work in a number of the fine patriotic societies of our country; the Belgian Relief Committee, under Mrs. Henry H. Knox, which has clone phenomenal work in the three months of its existence, and whose report is later given in detail; and the Emergency Committee under Mrs. Herman A. Prosser, which has a fund already established, and is. in close touch with Major Arthur S. Dwight, ready to act when necessity arises. The officers of the Auxiliary feel more than gratified at the response so far received, and in a later issue will print extracts from letters, if permission can be gotten from the writers, showing the interest and enthusiasm that have beer aroused by the formation of a Woman's Auxiliary. Answers have even come from far Korea "the hermit nation," from Australia, from South America, showing what a bond of sympathy and, helpfulness is in process of growth. It is our sad duty to announce the death of our Treasurer, Mrs. George D. Baryon, who, from the very inception of our plan to organize, was an inspiring and valuable co-worker. Her place will be difficult to fill. Mrs. Arthur S. Dwight is Acting Treasurer at present. The Auxiliary wishes to express its heartiest thanks to Mr. Stoughton, the genial and efficient Secretary of the A. I. M. E., for his cooperation and valuable suggestions in the difficult work of organizing. He has indeed been "a guide, philosopher and friend." SUSANNE M. IHLSENG (MRS. AXEL 0.), Corresponding Secretary.

Jan 7, 1917

By E. H. Cho

INTRODUCTION Activated charcoal has been used for several centuries in many capacities including the recovery, isolation and purification of various materials (1). The first use of charcoal in a gold metallurgical system was in the extraction of gold after chlorination (2, 3,4). The gold was dissolved in a chlorine system and subsequently filtered through charcoal. The application of charcoal with cyanide extraction was patented by Johnston (5) in 1894 and adopted commercially in Australia in 1897. The process consisted of dissolving the gold and silver in a potassium cyanide solution and passing it through a series of charcoal filters. The charcoal was subsequently smelted to recover the gold and silver. The interest in the use of charcoal diminished in the first part of the twentieth century as the practice of the use of zinc as a precipitating agent increased. However, in 1916, the Yuanmi Mine in Australia replaced their zinc precipitation plant with a charcoal adsorption plant. In 1926, Scott and Gross (7) of the U. S. Bureau of Mines con- ducted extensive research on the adsorption of gold and silver from cyanide leach solutions. Among their findings was the result that the most important factor in improving the adsorptive power of charcoal was heat treatment with oxidation by air or steam. The work of Zadra (8) in 1952 stimulated renewed interest in the use of activated charcoal in gold and silver recovery with the development of a method of recovery of the gold and silver from the charcoal other than its destruction by burning. The process involved simultaneous desorption

Jan 1, 1983

By A. M. Gsudin, F. W. Bloecher, C. S. Chan-s, P. L. De Bruyn

M ANY elements can now be obtained in radioactive form. The radioisotopes have the same chemical properties as the corresponding inactive forms, differing from them only by their nuclear instability. This combination of properties permits radioelements to act as atomic tracers, the tracer atoms revealing themselves at the time of their decay with emission of electrons and positrons (beta radiation), helium nuclei (alpha radiation), or electromagnetic radiation (gamma radiation). The tracer technique is particularly attractive for the study of surface chemistry problems in general and flotation problems in particular because of its extreme sensitivity. A large proportion of the ionizing events, initiated by the characteristic decay emissions in a radioactive sample, can be recorded by radiation probes of suitable design and geometry. An idea of this sensitivity can be gathered from the following example: assume that 0.001 mg of pure RaD (radiolead), a beta-ray emitter, is used in a flota¬tion tracer experiment. This is 1210 X 10-1 mole; since the fraction trans¬formed per second (the so-called decay constant), is 9.92 X 10-10, the number of ionizing events per second would be (6.023 X 1023 X y,,, X 10-1) X 9.92 X 10-10 = 2.845 X 106. (The decay constant is expressed in sec-'. Its product with the half life, expressed in seconds, is the pure number, natural logarithm of 2 = 0.693. The half life is the length of time required for decay of one half of the total number of radioactive atoms of one particular type.) (See reference (1) at the end of this article.)

Jan 1, 1948

By D. L. Katz

A PHASE diagram showing boundary curve and quantity of liquid in the two-phase region was determined for a mixture of natural gas and natural gasoline in the region of its critical conditions. The tempera-tures and pressures of phase measurements were in the range of 85° to 212° F. and 1300 to 2600 lb, per sq. in., respectively, with the critical conditions at 169.5° F. and 2615 lb. per sq. in. abs, Color phenomena were observed in the region of the boundary curve from 102° to 192° F. Approximate densities of the single-phase and two-phase regions and analysis of the system are included. Boundary curves between the single-phase and the two-phase regions have been determined for several binary mixtures containing hydro-carbons. 2,3,4,6,7,10,11,12,14 These investigators did not report the relative amounts of liquid and vapor within the two-phase region. The equilib-rium values obtained from the dew-point and bubble-point data can be used to compute the lines showing percentage of liquid on the pressure-temperature phase diagrams but the positions of the lines near the critical temperature and pressure are uncertain. Relative amounts of vapor and liquid were obtained for a gasoline and a naphtha' within the two-phase area but not in, the region of the critical temperature and pressure. The bubble-point and dew-point lines, as well as the percentage liquid lines within the two-phase region, were determined by visual observations in glass apparatus.

Jan 1, 1939

Cortez Gold Mines operated a conventional 2,100 mtpd (2, 300 stpd) cyanidation plant until the 5 million ton ore body was worked out in 1973. (See Gold and Silver Cyanidation Plant Practice by F. W. McQuiston, Jr. and R. S. Shoemaker, Society of Mining Engineers, AIME 1975.) Sub-grade material was dump leached at the mine -mill location in 1971, and the resulting pregnant solutions were added to the feed in the plant's Merrill-Crowe precipitation unit for gold recovery. In early 1973, however, Cortez put into operation their Gold Acres mine which was located about 13 krn (8 miles) to the west of the 'Cortez mine. Economics at that time dictated the heap leaching of the lower grade portion of the ore body with the higher grade being trucked to the Cortez plant for milling. Leach ore was moved directly from the open pits to prepared leach pads located on a gently sloping terrain of 570 grade. Preliminary pad preparation at the leach site included removal of vegetation which was composed of sagebrush and grading of the base. Pads were comprised of mostly minus 74 micron (200 mesh) materials and were made of clay-silt or slime tailings spread on the pad area in thin 50 to 75 mm (2 to 3 in. ) layers, compacted with a vibrating roller compactor to a depth of about 380 mm (15 in.). This was followed with a 100 mrn (4 in.) layer of coarse rock to prevent erosion on the pad and to allow solutions to move laterally under the heaps. Leach solutions normally traveled the length of the heaps and were collected in plastic-lined ditches from which they flowed by gravity to the pregnant solution storage pond. Both pregnant and barren ponds were constructed in the same manner as the leach pads - being lined with compacted tailings or clay silts. The Gold Acres facility required pregnant solution storage of 6 million liters (1.6 million gal) and barren storage of 3.8 million liters (1.0 million gal) designed to handle two to three days of heap drainage or to retain run-off from a major rainfall. Various heap heights were tried including 3, 6, and 9 meters (10, 20, and 30 ft), with a 6 m (20 ft) height selected. Ore was dumped by trucks in a single 6 m (20 ft) lift using a D8 Caterpillar dozer for

Jan 1, 1981

By L. D. Godshall

A great deal has been written of late regarding the loss of silver in assaying; very discordant results have been published by different writers, and much uncertainty exists concerning even approximate losses in a careful determination of silver, as represented by a fire-assay. In the present paper it has been the aim of the writer to determine as accurately as possible the losses sustained by silver, under certain specified conditions, during the process of cupellation. Such losses are well known to be due to absorption by the cupel and volatilization. The conditions, however, which govern these losses are not believed by the writer to be so well understood. The most important of these are : 1. The effect of variable quantities of silver used. 2. The temperature of cupellation. 3. The character and quantity of impurities in the lead button. 4. The weight of the lead button. 5. The nature of the cupel. The following experiments were made for the purpose of demonstrating, as nearly as possible, the total loss of silver in cupellation under the most favorable conditions to be obtained in commercial assaying. Chemically pure silver and pure lead were taken. The latter was obtained from test-lead, first melted into a bar, from which pieces of the desired weight were cut and accurately weighed. The experiments recorded in this paper were planned by the writer, but executed throughout by Mr. J. N. Walker, whose ability as an accurate, careful and painstaking assayer is too well known and recognized throughout the West to require any further endorsement from me.

Jan 1, 1897

By Wilford L. Stork

Certain influences of oxygen on iron have been known for many years and it has always been considered one of the worst enemies of the iron and steel founders. Nobody had a good word for it, hence little was done to make use of this oxygen. In all the fields of foundry practice, the desideratum was "melt without oxidation of the metal." In the consideration of the influence of oxygen on cast iron, we must not confuse this condition with oxidized iron caused by poor melting conditions, due to a high bed, heavy charges, low coke ratio, excessive melting rate, high blast, or poor charging. It is admitted that oxygen absorbed by iron melted under these conditions has a deleterious effect on the properties of the iron. The writer has had experience both in the melting under such poor conditions and in remedying these bad conditions and considers the product far inferior to iron melted under normal conditions. As stated by Dr. Richard Moldenke,l such iron has a higher melting point and high combined carbon, is sluggish, and contains slags and oxides in solution in the liquid, causing slag inclusions and gas occlusions, 'thus producing defective castings. This oxidized condition cannot be counteracted or removed by any of the known deoxidizers; it can be remedied only by proper melting conditions. Such iron is redly burned, whereas the iron considered in this paper was melted under normal conditions with moderate blast, correct bed height, light charges of iron, and low coke consumption and is not in this category at all. In 1914, the late J. E. Johnson, Jr., startled the metallurgists of the . world when he published his results on the advantages of oxygen on cast iron.2 His work is so convincing and so logical, in spite of the common and well-established notions on the subject, that nobody has been able to refute a single argument. Such an eminent authority on iron and steel metallurgy as Prof. H. M. Howe has accepted the work in all its details in his latest book.3 The work of J. E. Johnson, Jr., has revolutionized the metallurgy of cast iron and it seems apparent that all future work must include an oxygen determination just as we include silicon, sul-

Jan 1, 1920

By J. B. Clemmer, W. L. Lennemann, J. B. Rosenbaum

Security restrictions on processing uranium raw materials to yellow cake were lifted in August 1955, coincidental with the Geneva Conference on Peaceful Uses of Atomic Energy. Numerous reports and technical papers on uranium extraction and recovery methods have appeared since that time, and it is doubtful that another review of past and current practices would add much to the technical literature. Development of some promising procedures was arrested, perhaps temporarily, by mechanical handling problems or peculiarities in the chemistry of uranium and associated elements. Some methods have been incompletely evaluated and still others that tested well in the laboratory and pilot plant are dormant because of competition from other processes, or because of their restricted applicability to particular ore types that have not reached quantity production. In view of the vast number of new ideas and procedures that have been advanced, considered, and tested, it would be futile to attempt a comprehensive survey in this article. Only a cross section of the field, based on random sampling, can be provided here. The authors have chosen, therefore, to discuss some innovations that may provide a clue to uranium ore processing techniques of the future. An effort has been made to select unpublicized new metallurgical techniques or interesting applications of established principles and procedures. With the two exceptions noted later, all the research to be described has been sponsored by the AEC. Physical Beneficiation: Individuals and firms engaged in mining and processing uranium ores, and in related research activities, have often had considerable experience in ore dressing. As might be expected, therefore, a prodigious amount of work has been done on physical beneficiation testing of uranium ores, particularly in efforts to concentrate subgrade materials. Although some success has been attained on specific ores by gravity concentration and flotation, ratios of concentration have generally been low and there has been difficulty in making a throwaway tailing.

Jan 9, 1957

There is plenty of sulphur available but not at the price currently being paid for brimstone. Immediate shortages may be felt before the market adjusts, making marginal sources and by-product sulphur and acid available. (See P. 403) Government aid for mineral exploration is available and regulations governing applications are available from The Defense Minerals Administration, Dept. of Interior. lust ask for M0-5 and also for the contract form which is MP-103.

Jan 5, 1951

By CLAYTON C. BALL

In the year 1948, more than ever before, the coal industry established itself on the threshold of a new and exciting future expansion. While production did not equal the wartime and peacetime peaks of 1944 and 1947, it was, in review, a good coal year. During the latter part of the year a combination of mild weather, record stock piling, and general business slackening reduced coal demand to the extent that marginal mines suspended operations, while mines remaining active found it necessary to renew their attention to producing better products at lower operating costs.

Jan 1, 1949

By M. I. Kabir, R. S. Schechter, L. W. Lake

This paper presents the development and application of a novel scaling technique that, when used with a streamline model, causes a "bundle" of one-dimensional (1-D) problems to reduce to a single 1-D calculation. The 1-D bundle is the streamline representation of a two-dimensional (2-D) problem. The 1-D calculation accounts for chemical-rock interactions and the streamline model for areal sweep. The scaling technique significantly reduces computation time, is readily modified to desktop calculations, and can be applied to both absorbing and reacting species. The work was sponsored by the US Bureau of Mines.

Jan 1, 1986