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By Gilberto Yanarico Apaza

A través de estudios electrocinéticas, electroquímicos, y de flotación, se ha confirmado que la flotación de arsenopirita, ocurre debido a la formación de dixantogenato isopropílico, por la oxidación del colector en la superficie del mineral. Este fenómeno se promueve en condiciones ácidas, lo que no es nuestro caso; Sin embargo, se evita la flotación en condiciones alcalinas donde se forman hidróxidos de fierro y arseniatos en la superficie de arsenopirita y variedades de minerales de arsénico.

Sep 1, 2017

By Edwin C. Reeder

This is one of a series of papers dealing with mining methods and costs prepared under the sponsorship of end in cooperation with the United States Bureau of Mines. The mining methods described in this paper are those used in one of the large mines producing fluorspar in the Kentucky-Illinois fluorspar field, located in southern Illinois and western Kentucky on the Ohio River. The occurrence of ore and the methods of wining are similar to those in other mines in the district; therefore information regarding methods and the results obtained should be of interest. Improvements in methods have been made as experience developed the need of them. The trine is situated at Rosiclare, Ill., on the Illinois Central Railroad, and shipments are also made b r barge on the Ohio River.

Jan 1, 1930

By Carlos Ortiz, Pedro Quispealaya

"En este trabajo se detalla las experiencias de innovación de operaciones en una mina subterránea, logrando una visión profesional remota hacia los operadores de: Locomotoras durante la trayectoria de retroceso, Inspección de piques, el arranque y parada de equipos etc. En todos estos empleamos dispositivos electrónicos versátiles en tamaño, peso, capacidad de almacenamiento en memoria y otras relacionadas a la comunicación digital. En esta oportunidad en especial nos referimos a cámaras de video y transmisores aplicando tecnología inalámbrica."

Sep 1, 2017

By B. C. Allen

The interface energies of chronzium, molybdenunz. hugsten, and their solid-solution alloys Cv-35Re, MO-33Re, and UJ-25Re were studied at 0.6 to 1.0 of the absolllte liquidus ter)zpe,vature using fiz&apos;e )izethods. Liquid surface tension, yv , was deter mined clsing the pendant-drop and drop-weight methods. Results are, respectizlely, 1700, 2370, and 2480 +100 dynes per ct for the rhernium -containing alloys and essentially the same as tlwse reported for liquid chro)riln, trolybdenum, and tungsten. Average solid slrjace energy, rsv< xias ))zeasured using tlre fiber-extetlsion method. The ratio of ysS, the acerage high-angle grain-boundary energy, to ySV cclas jolnd fronz grain-bolzdary grooue angles fort)zed at the surface in an inert atrfizosphere. Absolllte iute?:face energies were deterawined using ?nultip/rase equilibria involzing suitable liquids of known surface tension (tin, silver). Interpretation of the experimented results in view of pvobable tenzperatzcre, orientation, and purity effects giz,e the follouling approximations in ergs per sq ctn: ysv (i2lo. Mo-33Re) - 2100, ySS (Mo, Mo-33Re) - 800, rr (defornzation twins in MO-33Re at 1200"C) - 800. ysV (Cr. Cr-35Re) - 2400. YSS (CY, Cr-35Re) - 1000. Probably Ylv- YSV- 2500 for tungsten and W-25Re, giving yss (It&apos;, W-25Re) - 900. The interface energies of solid and liqid ch?&apos;omiu?.z, nolybdenu?rr, and tungsten are not geatly aff&apos;ected by rhenium and therefore are not a ttlajor factor in the ductili zing rhenium effect in Croup VI-A metals. THE interface energies of the refractory Group VI-A metals, chromium, molybdenum, and tungsten, are not well-established. The objective of this investigation was to study the liquid surface tension, solid surface energy, and grain-boundary energy of these metals and compare them to those found for the bcc solid-solution alloys, Cr-35e,&apos; 0-33e,&apos; and -25e. Five techniques were used to measure interface energies in high-purity polycrystal rod, wire, and sheet at 0.6 to 1.0 of the absolute liquidus temperature. The alloys were chosen to see if there was any connection between interface-energy behavior and the ductilizing rhenium effecL4j5 EXPERIMENTAL WORK Materials. A description of the materials used is presented in Table I. Chromium rod was prepared by arc melting iodide process crystals supplied by Chromallo Cor., hot extruding, and warm swaging to 0.63-cm-diam rod.6 The sheet was prepared by rolling as-extruded rod to 95 pct reduction in area from a hydrogen furnace at 800" to 900°C and surface grinding off 0.02 cm from each face. Cr-35Re rod was prepared by arc melting sintered rhenium powder and iodide chromium crystals, warm rod rolling to 50 pct reduction in area in cans, and swaging to 60 pct reduction in area at 1100" to 1200°C. Some of the rod was warm-rolled to sheet and then surface-ground. Portions of swaged chromium and Cr-35Re were further reduced by swaging and drawing to 0.013-cm-diam wire by the General Electric Co. Mo-33Re and W-25Re rod, sheet, and wire were provided by Chase Brass and Copper Co. The molybdenum sheet consisted of two lots, both essentially the same except for the carbon content. Liquid Surface Tension. The liquid surface tension of Cr-35Re, Mo-33Re, and W-25Re was measured by a combination of pendant-drop and drop-weight methods using techniques already decribed." Following out-gassing, molten drops were formed on the ends of centerless-ground Mo-33Re and W-25Re rods by electron bombardment at 5 x 106 mm. Similar drops were formed on outgassed Cr-35Re rods by induction heating under 1 atm of 99.995 pct Ar. Solid Surface Energy. Solid surface energy was measured by conducting microcreep experiments on molybdenum, Mo-33Re, chromium, and Cr-35Re wires at 2350°, 2306, 1550°, and 180O°C, respectively. In preparation, gage marks -2.5 cm apart and -0.001 cm deep were circumferentially scribed on the wire with a razor blade. Weights of the wire material were then attached. Five to seven reasonably straight wires were hung in a container made out of the wire material. The free end was placed through a small hole in the removable top and secured by bending a small portion 90 deg. The containers not only tended to provide vapor-solid equilibrium for the wires but also protected them from gaseous impurities. They were nominally 2.5 cm in diam by 5 cm high and were made from extruded chromium rod, Cr-35Re arc casting, molybdenum bar stock, or welded Mo-33Re sheet. After deg re as ing, the assembly was outgassed at a relatively low temperature to 2 x 10"5 mm and then recrystallized 2 to 8 hr at the creep temperature in a rhenium-element resistance furnace. The static argon atmosphere was gettered by tantalum radiation shielding. Specimen temperature was measured optically to 25"C using calibration with known melting points and blackbody conditions. The wires generally developed a stable bamboo-type structure according to Fig, l(b), (c), and (d) and retained their gage marks [upper portion of Fig. l(d)]. One or two of the weights were clipped off to provide a low load for the creep anneal. To minimize the possibility of bending or breakage, the wires remained attached to the top of the annealing container which was held to keep the wires vertical. The distance between gage marks was

Jan 1, 1967

By George Haag

El shotcrete tiene una función importante en el sostenimiento y protección de una excavación subterránea. En ese sentido, el presente texto señala los tipos de shotcrete (mezcla seca y mojada) ventajas, clases de equipo, provisión de aire, agua, mangueras, inyectores, la clase de aditivos, los tipos de segregados, los análisis de costos, seguridad, tiempo y otros factores.

Jul 1, 1977

By William R. Vogel

The Bureau of Mines Minerals Information organization collects worldwide data on virtually every commercially important nonfuel mineral commodity. These data form the base for tracking and assessing the health of the minerals sector of the U.S. economy. This data collection activity was instituted by the 47th Congress in an appropriations act of August 7, 1882 (22 Stat. 329), to place the collection of mineral statistics on an annual basis. The most recent authority for the Bureau of Mines Minerals Information activity is the National Materials and Minerals Policy, Research and Development Act of 1980 (Public Law 96-479, 96th Congress), which strengthens protection for proprietary data provided to the U.S. Department of the Interior by persons or firms engaged in any phase of mineral or mineral- material production or consumption.

Jan 1, 1988

By M. M. Rao, P. G. Winchell, R. J. Russell

A detailed analysis has been used to correlate the avalable thermodynami c da In on iron-ric11 Fe-Ni (41loys in the body-centered a, and the face-centered y phases. The inp ut injovrt~ation required by the a am lysis consists of tile heat of the a, to y transformation at 1123°K, the heat of mixing of y at 1123°K, tile specific heats of both a, and y (decomposed into Debye, electronic, and magnelic contributions), and the positional and magnetic entropies of both a, and y. PYLrrzary oirt.bul of the analysis is the free energy of each phase as a Junction of temperature and composition. FOr Fe-Ni alloys the adjustment of twenty-one parunletevs allows the accurate reproduction of enthalpy data for both phases, the heat of mixing- for y, the a/y equilibrinm compositions in the Fe-Ni phase diagram, and the usually accepted enthalpy and entropy of a and y iron. Also obtaitzed are fuirly accurate reproductions of electronic specific heat coefficients predicted from electron- to-atom ratio interpolations and To temperatuves eslimanted from transformation studies. Also considered in the calculation are the elastic constants, Curie temperatures, saturation magnlelizalion values, and indications of short- range order. The measnred activity coefficient of iron in anstetnite could not be accurately matched. The major source of uncertainty in the model is thought to be the magnetic contribution to the entropy of austenite. Calcrclations were extended to Fe-ni-C alloys using available carbon-acliuity data. The free energy of transformation from martensile to r at fixed composition was obtained as a function of nickel and carbon contetzt, and binary thetal-carbon phase diagrams Were estimaled as a function of nickel contenl. We needed thermodynamic information for Fe-Ni and Fe-Ni-C alloys at temperatures between 400" and 800°K in order to interpret the results of several phase-transformation studies. The most recent theoretical analysis of the thermodynamics of Fe-Nialloysl was based on a lumped-parameter, regular-solution model and used the Fe-Ni phase diagram available at that time.&apos; Because significant difficulties were encountered in attempting to extend this analysis to Fe-Ni-C alloys, and because more experimental data has become available recently, we decided to attempt a new correlation. The analysis used here allows the extrapolation of measured and calculated thermodynamic values to lower temperatures and the extension of the thermodynamic analysis to Fe-Ni-C alloys. The structure of this correlation consists of expressions containing a total of twenty-one adjustable parameters. The forms of these expressions are discussed in the next section; however, a less formal summary is presented now to provide a physical overview of the model and to indicate its connections to prior work. Primary input information for this correlation is described below. The measured values of the specific heat of iron3 and its analysis475 and theoretical estimates of the specific heat of y* iron at low tempera- loys at 1123°K has been measured by solution calori-metry.7 The enthalpies of both a, and y have been measured most recently by Scheil and Saftig,B who used a dry-ice calorimeter. These data are used to formulate expressions for the heat of mixing of y and the heat of transformation of a, to y both at 1123°K. The a and y solubility limits in the Fe-Ni phase diagram have been redetermined recently9 by methods which assure a close approach to equilibrium. The a to y transformation can occur without change in nickel content or free energy at a temperature called TO; TO temperatures for various nickel contents have been estimated from transformation studies. The computed free-energy functions are adjusted by means of the parameters to fit both the phase diagram and the TO temperatures. Primary emphasis is placed on the phase diagram fit. Iron activities have been measured in Fe-Ni austenite10 between 973" and 1173°K. These activity data, which cannot be fitted accurately with our model, indicate that iron is substantially ideal in iron-rich austenite. Secondary, but helpful, information for the present correlation is provided by neutron diffraction and saturation magnetization measurements on both body-centered and face-centered Fe-Ni alloys."-&apos;3 These results were interpreted11 in terms of composition-insensitive, localized magnetic moments on both iron

Jan 1, 1968

By L. H. McGuire

Many coal beds in the State of Washington, pitching as much as 90°, offer unusual mining conditions. This paper describes methods and safe practices of mechanized mining in pitching bituminous-coal beds that have attracted the attention of mining people from most of the coal-producing countries of the world. The development and use of continuous miners as part of the mechanized program apply particularly to the Roslyn-Cle Elum coalfield, Kittitas County, Wash. All three mines now operating in the field use continuous miners and during 1957 furnished 72 percent of the State&apos;s total coal production. Mining operations are now conducted in three coal beds of the Roslyn-Cle Elum field. The coal measures range from 3-1/2 to 20 feet in thickness and vary in dip from 5° to 45° in the localities where the coal is mined. Some safety measures adopted by-the principal operating company in the field during the past 30 years of mechanized mining follow: Use of only permissible electrical or compressed-air-operated equipment on other than intake air; providing and using an explosion gallery to test repaired permissible electrical equipment before taking it underground; use of only compressed-air-operated drill augers in preference to permissible

Jan 1, 1959

By Joseph E. Matta, John C. LaScola, Fred N. Kissell

The Bureau of Mines investigated coal storage silos to determine how gassy coal must be for methane accumulations in a silo to become hazardous and where such accumulations are likely to occur. Methane concentrations were measured in the open space above the stored coal pile, in the pile, and in the reclaiming area. No methane layering was found in closed-top silos. Reclaiming areas were as gassy as the top part of the silos. Coal samples were collected from the conveyors entering the silos in order to assess the gassiness of the coal. No simple correlation was found between the gassiness of the coal stored and the measured methane concentrations. However, at mines where the average 24-hour gas emission from the conveyor belt samples was 14 ft3/ton or more, fans or open tops were used. It appears that a large fraction of the methane released during storage remains in the void space between the coal particles.

Jan 1, 1981

By Gustavo Quiquia Mucha

El presente texto describe la gestión social desarrollada por la Compañía Minera Milpo, basada en una consultaría previa, libre e informada sobre la exploración minera. Para ello, se incorpora el marco ideológico y metodólogico, cuyos principios se encuentran en el Convenio 169 de la OIT sobre pueblos indígenas y tribales en países independientes, los cuales han sido incorporados en las estrategias y líneas de intervención social de Compañía Minera Milpo S.A.A. en sus proyectos de exploración minera responsable.

Jan 1, 2012

By Michel Mellinger

This paper presents preliminary results of a project aimed at obtaining a better understanding of the genesis of gold mineralization in northern Saskatchewan using lithogeochemistry. The properties sampled were: Weedy Lake (B Zone), Waddy Lake (Komis Zone) and Wedge Lake (Twin Zone) in the La Range belt, and the Rio mine in the Flin Flon area. Although the three vein-type deposits rudied here (Weedy Lake. Waddy Lake, Rio deposit) occur in different geological situation . a common gold deposition mechanism appears to have been active at all three location . Hydrothermal fluids carrying sulphur in solution in exces of gold thio-complexes moved through fractured host-rocks until they reached a site where pyrite precipitation wa triggered. As pyrite precipitated, the a/ aAu activity ratio of the fluid decreased. until a critical thre hold was reached and gold thio-complexe were de tabilized . resulting in the co-precipitation of gold and pyrite. The conditions triggering the precipitation of pyrite appear to have been: the abundance of iron in host-rock ~ilicates at Waddy Lake. and temperature decrease upon the reaching of structural trap~ at both Weedy Lake and the Rio deposit. with additional involvement of carbonatizationrelated reactions between fluid and host-rocks for the latter. In addition to pyrite precipitation , potassic alteration of the mafic metavolcanics is observed at Waddy Lake. while at the Rio deposit, the extensive carbonatization of the host-rocks i coupled with the deposition of chlorite that may have been remobilized from the altered mafic host rocks. In both the B Zone at Weedy Lake and the Komis Zone at Waddy Lake, a di tinct vanadium signature give some clue about the direction in which the hydrothermal fluids have moved . and the interpretation made is con istent with the geological ituation in either case. As for the Wedge Lake deposits, the distinct base metals-precious metals a sociation within a sulphide-facies iron formation confirm the volcanic exhalative origin of this gold mineralization .

Jan 1, 1986

By Chester A. Rowland

La conminución de Ios minerales es, generalmente, una etapa de preparación de la alimentación para las subsiguientes etapas del proceso. La molienda, fase de conminución de productos finos, requiere una gran inversión de capital y frecuentemente es el área de máxima utilización de potencia y de materiales resistentes al desgaste. La molienda se produce normalmente en tambores rotativos que utilizan un medio de molienda que se pierde en la misma, al elevarse con la rotación del tambor, se rompe el mineral por combinación de los efectos de impacto, atrición y abrasión, hasta producir el producto especificado. El medio de molienda pueda ser: - El propio mineral (molienda autógena - primaria y secundaria). - Medio no metálico, natural o fabricado (pebbles) - Medio metálico (barras o bolas de acero) Este capítulo tratará de molinos de barras y bolas que utilicen medio metálico de molienda.

Jan 1, 1982

By John B. Hastings

THE origin of the watery vapors of vulcanism has always been an object of interest and speculation to the seismologist, and as theories of the genetic origin of ore-deposits have of late years been pretty well narrowed down to the expiring forces of plutonic action, the same question has had a lively interest for mining engineers and geologists, as is well shown by the discussions of the subject in our Transactions. The important part taken by volcanic emanations in the origin of pegmatites and quartz-veins, described in my paper, Origin of Pegmatite,1 and their latent power to concentrate into useful deposits such scattered gold as occurs in the Hartsel granite, make a discussion of their derivation but a natural third and final step. It is conceded that enormous amounts of vapor accompany volcanism, though perhaps we are apt to forget that steam has 1,700 times the volume of water, besides which the column seen over Vesuvius and other volcanoes is greatly mixed with air; the immensity of such volumes compared with solids and liquids is shown by the experiment of Gautier, who, by heating dessicated granite to 100° C., evolved from it uses 20 times, and steam 90 times, its own volume. Dana appraised the average amount of water left in ordinary rocks as 2.5 per cent. T. M. Read estimated that the Mississippi river carries to the sea annually 150,000,000 tons of rock material. If these Mississippi sediments, as deposited, contained 20 per cent. of water, it would be 600,000,000 cu. ft., or 4,500,000,000 American gallons, annually. Allowing the vapor suspended over a volcanic cone to be mixed with 80 per cent. of air, this amount of water converted into steam would replenish anew, every 9 min., a column 15,000 ft. high, 2,000 ft. in diameter at the base, and 10,000 ft. at the top. Read&apos;s estimate is only half of the amount given in a more recent and probably correct one .2

Jan 5, 1908

By V. Beskrovnaya

Oxidised lead-bearing ores of one of the deposits of Russian Federation represent complex raw materials. Its main components are lead (3.2%~4.7%), silver (100~300 g/t) and zinc (0.7%~0.8%). The sample is characterized as oxidized ore. Silicium (37.4%) and iron (33.2%) are its main com-ponents and present in oxide form. Lead presents as cerussite, anglesite and plumbojarosite have a subject role. Zinc occurs as smithsonite. Certain part of zinc is associated with manganese minerals (psylomelane-pyrolusite). Close association of valuables with manganese-iron mineralization is ob-served. Silver is present in native finely dispersed form. Three options of flowsheets have been developed to recover valuables from the ore. 1. Hydrometallurgical flowsheet of lead and silver recovery on the basis of chloride leaching. 2. Flotation. 3. Flotation -flotation tailings cyanidation. Hydrometallurgical flowsheet of ore processing on the basis of chloride leaching (option I) al-lows to achieve recovery into saleable products of 68.8% Pb and 70.2% Ag. High quality lead concentrate with 71.7% lead and 700 g/t silver was obtained during flotation (option 2). Flotation tailings cyanidation (option 3) provides 24% silver additional recovery (from the ore). Technical and economical evaluation demonstrated that ore flotation (option 2) and flotation with subsequent flotation tailings cyanidation (option 3) are the most cost-efficient. Option II is the most cost-efficient variant of 1 tonne of ore processing (9.05 US dollars).

Jan 1, 2014

By Shyam Chengalath, Johan Jeansson, Magnus Hörman

Down-The-Hole (DTH) drilling usually uses compressed air to power the hammer. However, there are now DTH hammers on the market which instead of compressed air use high pressure water to power the hammer. There are several benefits with using water DTH compared to air DTH, which are discussed in more detail in this paper. From a physics point of view many of the benefits arise from the fact that water is an incompressible media and air is not. Energy consumption is roughly a quarter compared to air, resulting in lower carbon emission and a lower energy bill. In the case of water DTH the water leaving the drill bit in the hole is at a low velocity and ambient pressure. However, with air DTH the air leaving the drill bit in the hole is at a high velocity and high pressure. This means that the risk of damaging surrounding structures in sensitive areas such as urban environments and dams, is greatly reduced with water DTH. In this paper two cases where water DTH is used in jet-grouting applications are discussed in detail. As these cases show there is a clear improvement in productivity when using water DTH hammers.

Sep 1, 2022

By Edward E. Johnson

The Bureau of Mines publishes in its ?Minerals Yearbook? a series of indexes on the domestic minerals industry. Among these are the index of physical volume of mineral production, indexes of stocks, and indexes of average unit mine value and implicit unit value, This report describes the material coverage of these indexes and the methods used in their construction. Detailed descriptions are given for several other mineral-oriented indexes regularly published by other government agencies. These descriptions give the index user a better understanding of what each index purports to measure and aids him in selecting the most appropriate index for his purpose.

Jan 1, 1965

By Edward E. Johnson

The Bureau of &apos;Mines publishes in its ?Minerals Yearbook? a series of indexes on the domestic minerals industry. Among these are the index of physical volume of mineral production, indexes of stocks, and indexes of average unit mine value and implicit unit value, This report describes the material coverage of these indexes and the methods used in their construction. Detailed descriptions are given for several other mineral-oriented indexes regularly published by other government agencies. These descriptions give the index user a better understanding of what each index purports to measure and aids him in selecting the most appropriate index for his purpose.

Jan 1, 1965

By Corwin L. Cooper

This paper, describing; the milling and cyanidation methods and costs at the Yellow Aster gold mine, is one of a series of papers being prepared by the Bureau of Mines on bold milling practices in the United States. Acknowledgments Acknowledgment is made to the executives of the Anglo American Mining Corporation, Ltd., for permission to publish this article, and to A. W. Frolli, manager, and other members of the company staff, for assistance` in preparing the, paper.

Jan 1, 1936

By R. J. St. Eloi

The Kidd Creek Copper Smelter has been expanded from its original design of 59,000 tonnes of copper per year to over 120,000 tonnes per year .. Modifications to the process gas handling system and acid plant have been made to accommodate this higher production rate and to .generally optimize the operation. The gas handling system associated with the continuous smelting process is discussed in terms of boiler accretions and modifications to minimize their impact on operations; design changes to effect reductions in high pressure drop duct configurations; material changes to overcome corrosion and plant additions to &apos;improve gas cleaning capability. The acid plant is reviewed with references to changes made to accommodate the increased S02 gas strength resulting from the higher smelting rates;

Jan 1, 1992

By Jaime Gómez, María Luisa Pecho

El presente trabajo de investigación aplicada tiene como fin dar a conocer los hallazgos experimentales obtenidos, a niveles de laboratorio y de Planta Piloto, sobre el comportamiento de los sulfuros comunes en la flotación con agua de mar

Sep 30, 2022