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By B. Silliman

THE occurrence of diamonds of some size in the gold-fields of California is by no means uncommon, and was noticed by me in a communication, to the California Academy of Science in 1867, when specimens of this gem, from at least five different localities, were exhibited. I then suggested that a more attentive examination of the heavy sands left in the sluices of hydraulic washings would in all probability detect diamonds, mingled with other rare species not commonly believed to have occurred in these sands. Mr. George A. Treadwell, of San Francisco, has 1at.ely sent me a small package of these sands, collected by him from the sluices of the " Spring Valley Gravel Mining Claim," Cherokee, Butte County, California. A microscopic examination shows these sands to abound in beautiful colorless zircons (hyacinths), of the form well known in the hyacinths of Expailly (France), associated with crystals of topaz, quartz in fragments, rounded grains 'of chromic and titanic iron, and

Oscar Rohn was born in Jackson, Wis., June 27, 1870. He attended the University of Wisconsin and there gained from Professor Van Hise his inspiration for scientific effort and useful attainment. While a student at Wisconsin he was interested in athletics and was a member of the first eight-oared crew that Wisconsin sent to compete with Eastern crews at Poughkeepsie. He was an instructor in the gymnasium for several years. He received his B. S. in 1895 at Wisconsin, specializing in engineering and geology. 1229

Jan 1, 1924

By John C. LaScola, David M. Hyman, William P. Diamond

The U.S. Department of the Interior, Bureau of Mines, has established a computer-implemented coalbed methane data base containing data representing over 2,000 coal samples from approximately 250 coalbeds located in 17 States and one Canadian Province. Space for approximately 130 sample characteristics is reserved for each sample record and is divided for access efficiency into three separate physical files. A software package was written to provide a user-friendly environment in which the three files can be manipulated simultaneously. These files can be used interactively in DATATRIEVE 11, a commercially available sorting, retrieval, and report-writing software package or in any FORTRAN-compatible system for statistical analysis. The data base has been established for coalbed methane research in response to the health and safety needs of the mining industry. Possible applications of the data base include mine planning related to the occurrence of gas, as well as delineating areas of resource recovery and utilization.

Jan 1, 1983

By A. Mitchell, M. Etienne

VARIOUS'-3 reports on the electroslag remelting process refer to the "thin skin of slag" existing around the slag pool and the solidifying ingot, but none considers the various mechanisms by which this layer forms and thus influences the surface quality of the ingot. A vertical section4,5 of the Cao-CaF2-Al2O3 diagram is shown in Fig. 1 between CaF2 and 6Al2.CaO3 From this, it is seen that a typical "70:30" CaF2:A1a3 slag will solidify to produce 6Al2O3.CaO primary phase in a eutectic matrix. The commercial slags contain sufficient CaO to produce* this composition by both the

Jan 1, 1969

By C. E. Lesher

Two processes for agglomerating fine sized ores with low temperature coke are described. One process (Orcarb) agglomerates ores with limited amounts of carbon; the other (ore-carbon pellets) pelletizes fine sized ores, using low temperature cokes as the binder. Data are presented on the products obtained when taconite, magnetite, and hematite concentrates and several titanium oxide ores were used. Reduction of finely divided oxide ores has long been a major metallurgical problem. Various methods of agglomerating, notably briquetting, sintering, nodulizing, and pelletizing, have been developed and are in industrial use. Carbon is the usual reducing agent for oxide ores and attempts have been made to agglomerate fine ores with coking coal in order to get the metallurgical advantages of intimate contact and increased particle sizes suitable for subsequent smelting or reduction.

Oct 1, 1955

By Walter E. Heinrichs

Before covering the separate methods used in mining geophysics, it may be well to mention some current basic geophysical prospecting concepts. As in most fields, a better understanding and means of studying these fundamentals usually provides the more common improvements, rather than new principles being discovered. The relative detail and complexity of most mining geology often results in the use of geophysics in problems it cannot solve. On the other hand, suitable applications are often ignored or left unrecognized. To minimize this, it is important to consider geophysics as a phase, or additional tool, in geological or exploration engineering.

Aug 1, 1956

By B. J. Klee

What is the economic basis for direct, continuous particle size measurement and control? First, precise grinding control is necessary to achieve and maintain a specified recovery and throughput. Second, throughput and recovery are direct functions of particle size-and these two factors control the economic performance of the ore concentration process. Third, only size-based control using a particle size and percent solids monitor (PSM) has achieved the necessary precise control. Recovery, throughput and cost can be accurately measured for various concentrator operating conditions if particle size is closely controlled. From such data the economic results of different particle size grind points can be analyzed. This will reveal the best combination of recovery and throughput to meet objectives established by financial management. Predictable, repeatable response to set-point selection is essential if the projected profitability of the mill is to be reached.

Jan 11, 1976

By C. A. Stetefeldt

In my paper on "The Consumption of Fuel in the Taylor Gas-Producer Plants at the Aspen and Marsac Mills" (Trans., xxiii., 134), I mentioned that in the plant which I had designed for the Ontario mill, the gas-tubes were to be covered with thin, corrugated sheet-iron, over which a coating of asbestos-magnesia would be spread in order to effect a good insulation and keep the gas as hot as possible. At the Ontario mill, two Stetefeldt furnaces and two revolving driers are fired with gas. One furnace is connected with a Taylor producer of 5 feet diameter, and the other furnace and the two driers are heated by the gas from a Taylor producer of 7 feet diameter. In the latter case the gas-tubes are necessarily somewhat long, and the cleaning of them takes time. In order to prevent overheating of the tubes during that operation, it has been found advantageous not to provide them with an insulating covering. If a tube becomes red-hot at any place by the burning of soot, this is at once observed, and the tube is closed until it cools down. The tubes con-

Jan 1, 1895

The Library of the above-named Societies is open from 9 A.M. to 10 P.M., except on holidays. It contains about 70,000 volumes and 90,000 pamphlets, including sets of technical periodicals and publications of scientific and technical societies. Members of the Institute, with few exceptions, are forced to spend a portion of their time in localities isolated from sources of information. To these the Library, through its Library Service Bureau, can render valuable service through correspondence; letters requesting information will receive especial attention. The Library is prepared to furnish references and photographic copies of articles on mining and metallurgical subjects; to determine the existence of mining maps, and to furnish general information on the geology and mineral resources of all countries. All communications should be made as definite as possible so that the information received may be what is desired and not include collateral matter which may not be of interest. The time spent in searching for such collateral matter will be saved, and the information will be sent more promptly and in more usable shape.

Jan 3, 1918

By G. C. Mudd, E. J. Myers

Within the last 15 years David Brown Gear Industries has manufactured approximately 200 large mill gears over 6m diam., 58 of them over 9 m and up to 12 m diam. The experience has not been without problems, due to a lack of clear understanding of the loads and stresses imposed on large gear wheels. American Gear Manufacturers Association (AGMA) practices suggest that a service factor be used for mill gears. But what is meant by "service factor"? The layman might be forgiven for believing that the term is synonymous with "safety factor," but this is certainly not true. The service factor is an aggregate of the following in some proportion: -An application factor, i.e., an allowance for the fact that systems do not run smoothly with uniform torque. -An ignorance factor covering the imperfections in the basic gear calculation. -Possibly a safety factor. In the following sections some of the ways in which the limits of applicability can be overstepped are discussed.

Jan 1, 1983

It is well to bring before you again the chief purpose of the National Research Council and of this its Division of Engineering, to stimulate others to make researches rather than to make them ourselves, because a given amount of our energy spent in inciting others will accomplish far more than if applied in executing them ourselves. This is because there are scattered through the numberless governmental, educational, and industrial laboratories of the country a very great number of investigators not only capable of being stimulated, but willing to aid in cooperative broadly planned research rather than to follow the haphazard methods of the past. Taken collectively, these laboratories and their personnel can produce an annual crop of knowledge the value of which is of the order rather of billions than of millions of dollars. I invite you to regard this potential product as a crop, to be planned, fertilized, harvested, and distributed with the sane order of statesmanship, the same breadth of view, with which we treat any other great human product or achievement, whether agricultural, industrial, or transportational.

Jan 1, 1919

No early records of coal in Iowa have been found, although it is very probable that coal along the Mississippi, in the northeastern corner of the state, was seen very early. The United States Census of 1840 showed a production of 400 tons, mined of course in 1839, and the earliest mining, was in Jefferson and Fairfield Counties where the coal was hauled by wagons to shops in the Mississippi River towns years before any railroad was built in the state. In 1840 mines were opened in Van Buren County, near Farmington and Douds, and in Scott County, near Jamestown, all of the product being used locally.' In 1844 D. D. Owen reported seeing mines in the tongue of land between the Rock and Mississippi Rivers, in one of them the coal being 5 to 6 ft. thick, and several other seams south of this locality? In the, late forties a number of small mines were opened in various parts of the state, and in following years in practically every county having coal. The Mystic seam was first opened in 1857 in Appanoose County, since then consistently one of the large producing areas in the state. Consumption was local until the Milwaukee Railroad was built through the county in 1887.1

Jan 1, 1942

By J. B. Scuffham, G. A. Rowden

The use of ammonia as a leaching agent has been well-documented but only recently have its advantages been fully exploited on a commercial basis. When compared with conventional sulfuric acid leaching processes, the major advantage of ammoniacal systems is their ability to reject iron and many acid consuming gangue materials. Although metallic copper, nickel, zinc, etc. are dissolved rapidly in ammoniacal liquors at ambient temperature in the presence of air the sulfide ores of these metals are more resistant to this treatment. Sherritt Gordon Mines in Canada treats sulfide concentrates at its Fort Saskatchewan plant under pressure with ammoniacal am- monium sulfate solution to solubilize the non-ferrous metal values. Typical leach operating conditions are 80-95°C and 115- 128 psig. Although the metals present in the ammonical solution could be recovered via solvent extraction techniques, Sherritt Gordon Mines currently operates a pressure reduction process using hydrogen to yield metal powders directly from the ammoniacal solution. The basic Sherritt Gordon technology has been applied world wide for the treatment of nickel/cobalt concentrates.

Jan 12, 1973

By J. Wayne Erickson

Hundreds of millions of dollars have been spent to discover or purchase uranium resources that cannot, or should not, be mined with conventional methods if human, natural and financial resources are to be conserved. Three years ago, an industry-supported research stud was initiated to determine whether a safer and more efficient (in terms of cost and environment) uranium mining method could be designed to replace existing techniques. As a result of this study, the "underground in situ" method was conceived and developed to the stage where it is now feasible. This approach involves: (1) sinking a shaft; (2) driving a drift on the ore horizon the length of the ore body; (3) drilling almost-horizontal long holes the width of the ore body; and (4) oxidizing and leaching the uranium drawn from these holes. The method is unique in that the uranium is removed with a minimum of disturbance to the natural hydrology of host or surrounding sands.

Jan 11, 1978

By W. H. Fluker

Until recently, the universal practice in New Zealand was dry-crushing and direct cyaniding. With ores containing no mineral sulphides, and little or no coarse gold, 'this method, in spite of its many disadvantages, gave excellent results, and was by far the best one available, pending the solution of the slimes-problem. But the situation has now been changed. The successful treatment of the slimes, enabling the mines not only to do away with dry-crushing, but also to deal with the mineralized ores of the lower levels, which are, for obvious reasons, quite unsuited to that method of treatment, has made wetcrushing universal; and this may be taken as satisfactory proof of its superiority over the former practice. In the lack of accurate information from plants operating successfully, particulars of experimental trials carried out on a working-scale at the Waitekauri Extended mine, Maratoto,

Jan 1, 1903

WE the undersigned, being all persons of full age and citizens of the United States, and a majority residents of the State of New York, desiring to form a corporation pursuant to the provisions of the Membership Corporations Law for the purpose of incorporating, as provided in Section 5 of Article I. of said law, the existing unincorporated association known as American Institute of Mining Engineers, do hereby make, acknowledge and file this Certificate for that purpose, and do Certify as follows: I. That the American Institute of Mining Engineers is an unincorporated association organized and existing with the object of promoting the arts and sciences connected with the economic production of the useful minerals and metals and the welfare of those employed in these industries by means of meetings for social intercourse and the reading and discussion of professional papers, and to circulate by means of publications among its members and associates the information thus obtained. II. That the persons duly appointed or designated to manage the affairs of said association are designated by the rules thereof Members of its Council; that the undersigned are all members of said Council as the same was constituted on the 29th day of December, 1904.

Jan 1, 1923

Raymond Weir Smyth, born Nov. 3, 1888, was the son of Herbert Weir Smyth, professor of Greek Literature at Harvard University. He graduated (A. B.) from Harvard in 1909 and later pursued advanced studies there in chemistry and in metallurgy. He held the position of metallurgist for the American Steel and Wire Co. at Worcester, Mass., and also for the Steel and Tube Co. at Youngstomn, Ohio. For a time he was inspector of munitions for the British Government and stationed at the Railway Steel and Spring Co. at Latrobe, Pa. For a short time, in 1917, he was Inspector of Ordnance for the U. S. Government, and the following year, having entered the U. S. Naval Reserve Force, he was ordered in a similar capacity to the Midvale Steel Co. In September, he removed to the Navy Yard, League Island, Philadelphia, to train for the obligatory minimum of six months' sea duty. There he contracted influenza, which was followed by pneumonia, from which he died, September 27, at the Navy Yard Hospital. Captain Braxton Bigelow* Captain Braxton Bigelow was the son of Major John B. Bigelow, U. S. A., retired, and grandson of the late John Bigelow, author, and Minister to France under President Grant. Captain Bigelow graduated

Jan 1, 1920

By Andrew Roy

THE Mahoning Valley coal region lies on the extreme northern outcrop of the Ohio coal-field, and all the mines, with one exception, are opened on the lower coal of the series, No. 1 of the Ohio Geological Survey. The coal ranges from an inch to five, six, and sometimes seven feet thickness, the workable height being between two and a half and six feet. There are two varieties of coal, known in market as "Briar Hill coal " and " Mineral Ridge coal;" both varieties are drawn from the same seam. The Briar Hill coal is generally called block coal, and is the kind so largely used in a raw state in smelting iron. It pos¬sesses a laminated structure, easily splitting into horizontal sheets, but is very difficult to break in the opposite direction. The faces of the layers are often covered with a soft, dead, carbonaceous material, like charcoal, and the whole seam throughout is marked by alternate layers of dead and bright-looking coal. In the act of combustion the coal neither swells nor changes form, the masses retaining their shapes until they fall to ashes in the furnace. The Mineral Ridge variety is much softer, and is also shorter in the grain than the Briar Hill. kind, and it contains a good deal of

Jan 1, 1876

By Richard A. Pomeroy

This mine, known also as the A very Mine, is situated on Petite Anse Island, Iberia Parish, Louisiana. The island is about four miles from Vermillion Bay, an arm of the Gulf of Mexico, and is one of four islands or hills surrounded by the sea-marsh, as shown in the accompanying map. (Fig. 1.) A fifth, Joe Jefferson's Island, or hill, is some distance from the sea-marsh. These five islands: Belle Isle, Cote Blanche,Grand Cote, Petite Anse and Jefferson, appear to be the tops of submerged hills, and occupy a line having nearly a northwest trend. To the north are a series of hillocks that extend at intervals to the hills of Northern Louisiana, which in turn appear to run into the Ozarks of Arkansas. Near the mine there is sandstone, also a thick vein of lignite. Bones of the mastodon have been

Jan 1, 1889

By H. J. Modi, P. L. De Bruyn

In recent years interest has been aroused in flotation rate studies both from a technical and a more practical aspect. With increasing fineness of grind becoming a necessity in treatment of low grade ores, differences in flotation rates of various size ranges will assume importance in the evaluation of overall recovery results. Theoretical analysis of flotation kinetics was initiated by Schuhmann, who sought to define flotation rate of a given mineral and specified size range in terms of certain physical variables of the flotation system. Using as a basis for his analysis the bubble- particle encounter hypothesis previously advanced by Gaudin, Schuhmann writes for the rate of flotation (R,) of particles of average size x, [ ]

Apr 1, 1956