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By J. Carr

Ring gear and pinions used as the final drive on large metallurgical grinding mills are expected to transmit their rated horsepower reliably for long periods of time. Duty is 24 hrs./ day. Life expectancy of such gear sets is of the order of 20 years; that is, each gear and pinion flank is expected to resist failure by pitting for 10 years. This means that for a dual pinion gear set having a ratio of 18.42:1.0 and a mill speed of 10 RPM, every gear tooth will see 105.12 x 106 surface contact stress cycles and every pinion tooth will see 968.15 x 106 surface contact stress cycles in a 10 year period. The allowable surface contact stress on the gear and pinion is determined by the material hardnesses. The rule being the higher the hardness, the higher the allowable surface contact stress may be.

Jan 1, 1985

By H. Grothe

El presente texto señala las posibildades técnicas y económicas en la instalación de una refinería de zinc y una fundición de plomo en el Perú. Para ello, se revisan los problemas técnicos que comprende (la materia prima y la elaboración). Respecto a los yacimientos y considerando como norma las extracciones actuales, se asegura la existencia de materias primas para un espacio prolongado de tiempo dentro de un período mínimo de 20 años. Asimismo, la calidad de las menas no sufrirá ninguna variación fundamental en este espacio de tiempo y las plantas de preparación existentes estarán en condiciones de suministrar a la nueva fundición suficientes concentrados, tanto en cantidad como en calidad.

Mar 1, 1960

By D. L. Jones

The leaching of natural chalcopyrite was studied in both ferric sulfate and ferric chloride solutions. The chemistry of the two reactions is quite different, with substantial sulfur oxidation occurring only in sulfate solutions. Ferric chloride is a more effective reagent, for the leaching rate is greatly increased with finer particles and higher (Fe+++), and unaffected by high (Fe++); none of these advantages are found with ferric sulfate. In addition, the morphology of leaching appears to be different, with ferric sulfate leaching preferentially along fissures or grain boundaries. The kinetics were found to be linear over an extended period, rather than parabolic as reported elsewhere. An explanation of the observed phenanena is proposed using the electrochemical theory of leaching, and experimental measurement of the mixed potential of the mineral during leaching.

Jan 1, 1976

By James K. B. Booth

The natural crustal abundances of the principle metals of commerce are examined in relation to production and prices for each metal. Two factors, the abundance x price ratio (BP factor) and abundance/production (B/T factor) are listed for each metal. Ideally, for these desirable commercial metals, each factor should be a constant and the same for all metals; comparing the divergences for the full list of metals allows conclusions to be drawn on the relative degree of natural availability of each metal and the ease or difficulty of winning the metal from the earth's crust. Plotting the two factors for each metal over the past decade of steady industrial usage illustrates the anomalous position of copper and, to a lesser degree, molybdenum and it is concluded that over the long term the price of copper will continue to rise steeply. Possible future prices for copper are examined and a suggested preferred order of ranking of the metals as exploration targets would be copper, nickel, tin, zinc, silver, molybdenum and lead, for the near term, with molybdenum possibly increasing its ranking in the list within the next decade.

Jan 1, 1971

By A. S. Ibrado

Research investigations on the chemistry of the adsorption of gold cyanide on activated carbon have mostly reduced the role of activated carbon as the provider of the large surface area needed for adsorption. Most do not go beyond suggesting that oxygen functional groups on carbon play a key role in the adsorption process. Our research shows that the nature of the material, specifically its structure, is a crucial factor in the adsorption equation. To delineate the effect of adsorbent properties, gold cyanide was adsorbed on a series of carbonaceous adsorbents, including lignite, coals, anthracites, carbon blacks, graphite and activated carbon, which covers wide variations of composition, surface acid group content, and degree of graphitization. The results show that the adsorption of gold cyanide per unit area of adsorbent is not related to the amount of oxygen groups on the surface or even the total oxygen content of the material. However, they show very strong correlation with the degree of graphitization of the adsorbent, which indicates that the graphitic plates of activated carbon play the most important role. The findings suggest that majority of the adsorption occurs on the plate faces of the graphite crystallites of activated carbon.

Jan 1, 1992

By Gieskieng, D. H.

Published tables of jaw crusher capacities are compiled for the most part from field performance data, interspersed with interpolations, extrapolations, various safety factors, and other modifications. Such a table attempts to balance and equalize field data from widely different materials, with differences of crushability, efficiency of feeding, sizing of the feed, and so on. The tests described in this paper were undertaken with the objectives of checking previously reported capacities; of studying the effects of various factors upon the capacity, including jaw plate curvature; and, if possible, of deriving a general capacity equation. Such an equation has been derived from the data obtained in these tests. It is given together with factors for its use. While more accuracy than is usually required may be obtained by careful application of the equation, it is of simple form and provides a convenient reference plane upon which the potential capacity of various crushers may be compared, and with which operating adjustments may be made on existing installations. The principal deviation in these tests from the usual approach consists of a laboratory technique which has been developed for the production of selected

Jan 1, 1949

By D. Orynbassar, N. Madani

This work addresses the problem of geostatistical simulation of cross-correlated variables by factorization approaches in the case when the sampling pattern is unequal. A solution is presented, based on a Co-Gibbs sampler algorithm, by which the missing values can be imputed. In this algorithm, a heterotopic simple cokriging approach is introduced to take into account the cross-dependency of the undersampled variable with the secondary variable that is more available over the entire region. A real gold deposit is employed to test the algorithm. The imputation results are compared with other Gibbs sampler techniques for which simple cokriging and simple kriging are used. The results show that heterotopic simple cokriging outperforms the other two techniques. The imputed values are then employed for the purpose of resource estimation by using principal component analysis (PCA) as a factorization technique, and the output compared with traditional factorization approaches where the heterotopic part of the data is removed. Comparison of the results of these two techniques shows that the latter leads to substantial losses of important information in the case of an unequal sampling pattern, while the former is capable of reproducing better recovery functions.

Aug 1, 2021

By L. M. English

A basic model has been developed to help assess methane control needs for longwall mining of coal in gassy areas. Rather than depending upon reservoir and rock mechanic theory, it uses an empirically-determined gas emission rate as an input and operates on the assumption that, within a specific region and zone, gas emissions will be relatively equivalent for uniform incremental volumes of gob created by mining. The computer program divides longwall panels into segments, keeps track of the face advance, and generates emission rates and volumes for both the entire panel and for individual zones within the panel by summing values for all undermined segments. This model can aid the determination of the number, size, and location of vertical wells or other methane control applications that are needed for gob gas control.

Jan 1, 1998

This list is part of the long-range conservation program of the Bureau of Mines and is intended for use by those interested in the Bureau's publications dealing with oil shale and shale oil. The items included represent 51 years of research by Bureau of Mines employees on oil shale and shale oil and are available at any U.S. depository library. DISTRIBUTION U.S. Bureau of Mines report series contain both free and sales publications. An asterisk (*) designates publications for sale. Such publications can be obtained from Superintendent of Documents U.S. Government Printing Office Washington, D.C. 20402

Jan 1, 1969

By Henry M. Howe

PART I. § 1. Introduction. After giving certain definitions, this paper gives the reasons which led to Roozeboom's form of the diagram of the freezing-point curves and general equilibrium of the iron-carbon compounds, steel and cast-iron ; and then those which led to replacing it with the present or double diagram, in which graphite is at all temperatures held to be the more stable and cementite the less stable (metastable) form of carbon. Next in § 10 the evidence supporting this greater stability of graphite is examined, then in § 17 that which seems to oppose it, and in § 22 a summary of the evidence is presented. The second part of the paper considers the topography of the graphite-iron diagram, rejecting summarily the solubility-lines based on the data of Charpy and Grenet and of Mannes-mann, on the ground that the data even on their face do not really point toward these lines, and that they are wholly incompetent to determine any solubility-lines whatsoever, because they report together with the dissolved carbon also an indeterminate quantity of cement-carbon, and because even such carbon as is actually dissolved, only in part represents the solubility of graphite, and in another and indeterminate part represents the solubility of cementite, or at least of carbon in presence of cementite as distinguished from graphite. It might be thought that graphite is but slightly soluble in iron, because of the absence of any suggestions of eutectoid graphite, corresponding to the eutectoid cementite of pearlite in very many cases in which the cast-iron seems to consist of ferrite and massive graphite only, and because of the micrographs of Goerens and Gutowsky. In these the primary austenite of cast-iron quenched but little below the eutectic freezing-

Jan 7, 1908

By R. M. Santmyers

Umber and sienna, like ocher, are naturally occurring mineral pig- ments composed largely of clay permeated with hydrated iron (ferric oxide), but they differ from ocher in that they also contain hydrated manganese oxide. The presence of manganese accounts for their browner color. In addition to silica and alumina (clay) and the coloring oxides of iron and manganese, these pigments often contain lime, barium, and other metallic salts as impurities. Sienna most nearly approaches ocher in chemical composition, and the chief distinction is its physical character. It grades into ocher with de- creasing iron content and into umber with increasing manganese content. Sienna is translucent rather than opaque and is more of a stain than a pigment; as the iron oxide content is rather high (often 60 to 80 per cent), the color is strong and rich and varies from pure brown to reddish brown. This pigment raw sienna, terra di Siena, and Italian earth. is known under several names: Burnt sienna is a pigment of an orange-brown tint made by cautionsly calcining raw sienna. It is divided into two grades; American, and Italian burnt sienna. American burnt sienna is a reddish-brown pigment containing from 25 to 60 per cent iron oxide (Fe2O3). One grade, found in Pennsylvania, analyses as high as 80 per cent and is mown as double strength sienna. Italian burnt sienna is a pigment generally containing more iron than the American product, averaging 60 to 75 per cent iron oxide.3 American pig- ments of the same iron content differ materially in shade, having a Havana- brown color, whereas the Italian is more of a maroon. Italian siennas when tinted with 20 per cent of white, show a bluish tint, whereas American siennas yield a brownish or yellowish hue. Raw umber, also known as Turkey umber, Levant umber, and terra ombra, is a greenish to yellowish brown siliceous and ferruginous earth, containing a considerable proportion of one or other of the higher oxides of manganese, Mng04 and MnO2." It is similar in many respects to raw sienna except that it is much coarser and contains more manganese oxide. All umbers contain over 5 per cent of manganese dioxide. Like sienna, umber is a permanent pigment, not being injured by light or by impure atmospheres. Burnt umber (velvet brown, chestnut brown, etc.), results from the calcination of raw umber. The color is much richer and warmer than that of the raw umber. The colors are equally permanent and can be used in conjunc- tion with all other durable pigments.

Sep 1, 1931

By I. R. Stevenson, J. G. Dunn, T. N. Smith, L. C. Mackey

An experimental flash reactor has been developed to simulate the operation of an industrial flash-smelter reaction shaft. Four concentrate materials of differing mineralogical compositions were characterised and then oxidised in the reaction shaft. The products were examined by chemical analysis to determine the extent of oxidation and by electron-probe microanalysis to determine the fate of individual particles. This programme of work enabled the influence of mineralogical composition and particle size on the extent of oxidation to be assessed

Jul 1, 1991

By Herry Poernomo, Agus Prasetya, Iga Trisnawati, Himawan Tri Bayu Murti Petrus, Gyan Prameswara, Panut Mulyono

We studied yttrium extraction from untreated zircon sand processing waste tailings. Xenotime mineral as the rare earth element source with an abundance of yttrium (REY) was detected in sufficient grade for extraction. As much as 9.03% yttrium exists in zircon tailings (analysed by X-ray fluorescence spectrometry). The presence of yttrium was confirmed by X-ray diffractometry in xenotime minerals, which are yttrium carriers (Y-PO4). The purpose of this research was to determine the effect of leaching conditions on yttrium recovery from zircon sand after alkaline fusion treatment. Alkaline fusion was chosen to decompose phosphate into hydroxide in the xenotimemineral,which will reduce further required hydrometallurgical processing.Alkaline fusionwas carried out for 3 h at 450 °C, with a ratio of sodium hydroxide to zircon tailings sand of ~ 1:1. The alkaline fusion product was leached with water, followed by hydrochloric acid treatment to leach the yttrium. Yttrium recovery reached 87% under optimum conditions (60 °C, 1MHCl, and solid-to-liquid ratio = 1/10 for 7.5 min). A suitable model for yttrium dissolution with hydrochloric acid was diffusion through a solid particle ash layer. The calculated activation energy (EA) for this model was 20.21 kJ/mol.

May 26, 2020

By J. Oré Iwanaga

El presente texto señala el uso de geocontenedores como una alternativa en la deshidratación de lodos líquidos ( relaves) a través del programa MATLAB que permite la determinación de los parámetros de diseño más importantes. La ejecución del programa se realizó en la planta concentradora de la Compañía Minera Raura, ubicada en la cordillera occidental entre Huánuco y Lima, sierra central del Perú donde se estableció la presión de bombeo (Po) y resistencia del geosintetico (T),a partir de datos conocidos como: perímetro (L) y peso específico del lodo líquido.

Jul 1, 2014

By Miguel Tapia, al et, Milenko Gonzalez, Sergio Giglio

El Encierro es un yacimiento de tipo pórfido Cu-Au del Mioceno superior ubicado en la zona intermedia entre las franjas de El Indio y Maricunga, en el norte de Chile. Está emplazado bajo un extenso lithocap que presenta evidencias de mineralización de tipo epitermal de alta sulfuración y que fue explorado entre 1987 y 2010 por varias empresas. En 2016, AMSA firmó un contrato de opción de compra con Barrick con el objeto de comprobar la existencia de un sistema tipo porfídico en profundidad con potencial económico. Cuatro campañas de perforación desarrolladas entre 2015 y 2020 permitieron probar que debajo del lithocap se encuentra un sistema porfídico de Cu-Au con leyes que se incrementan por debajo de la cota 3,000 m.

May 10, 2023

By A M. Nyembwe, A M. Garbers-Craig, R Cromarty

With the depletion of high-grade lump iron ore, concentrates have been identified as an alternative material for sinter making. Adding concentrates to the sinter mixture reduces sinter bed porosity and gas flow through the sinter bed. This will result in lower sinter strand productivity. A potential solution to this problem is to add concentrate in the form of micropellets. This study investigates the effect of concentrate and micropellet additions on the permeability of the sinter mixture. Permeability was measured on sinter mixtures containing ten to 40 per cent concentrates and micropellets at various moisture contents. The effect of concentrate and micropellet addition on the permeability–moisture relationship was examined. The results confirmed that the addition of concentrates into the sinter mix decreases the maximum permeability of the sinter bed. The incorporation of micropellets into the sinter mix reduced the permeability less than concentrate addition. The study also showed that the maximum permeability of sinter mixes containing concentrate is reached at the same moisture content as the sinter mixture without concentrate addition. For sinter mixes containing micropellets, additional water must be added to obtain maximum permeability. Parameters including the granule size, void fraction and angle of repose were also investigated to evaluate their effects on the sinter bed permeability.CITATION:Nyembwe, A M, Cromarty, R and Garbers-Craig, A M, 2015. Effect of concentrate and micropellet addition on iron ore sinter bed permeability, in Proceedings Iron Ore 2015, pp 69–76 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 13, 2015

By Jack R. Miller

This session has been organized to suggest to you that the development of direct reduction is important to the iron ore mining and coal mining industries. The papers presented this morning will include a discussion of the costs of making direct reduced iron (DRI), the iron ore and coal supplies needed to produce DRI, the financing of direct reduction (DR) projects and, probably most important, the impact of the DR development on the iron ore and coal industries. For starters, this opening presentation offers a brief statement about DR practice and DRI, under the title that should surprise no one: "Direct Reduction: What Is It?" There is always the chance? that a brief statement may become long and complicated. But, by mixing some slides borrowed from Hal Lownie with a larger number of photographs accumulated from other sources, I hope to avoid such pitfalls.

Jan 1, 1978

By Brad Gunn

Our program has been dictated by the necessity of broadening our markets through converting potash chemicals to fertilizers more in demand than potassium chloride. To this end, we have undertaken studies on methods of preparing potassium sulphate or potassium magnesium sulphate by rather simple conversion. When mixtures of sodium and magnesium sulphates are reacted with potassium chloride, the ratio of sodium to magnesium is quite pertinent. A range of ratios has been selected and the conversions of potassium chloride to sulphate have been assessed by cyclic operations. Results from experimental procedures for producing potassium nitrate are also avail-able. The influence on recovery for systems including organic solvents is assessed for a variety of situations.

Jan 1, 1971

By J. K. Whyatt

The Bureau of Mines, under a cooperative agreement with Callahan Mining Corp., measured rock displacement at the 4,7S0-ft level of the 5,100-ft-deep rectangular, timbered Caladay Shaft in northern Idaho. Displacements were measured with multiple-position borehole exten-someters (MPBX) installed 4 ft above the face and timber extensometers (TE) installed with the timber sets. This report presents the displacement data along with preliminary, qualitative observations of rock behavior. The measured displacements showed an instantaneous response to shaft sinking and significant time dependency. The relative magnitudes of displacement measured at the shaft walls were heavily influenced by local geologic structure and distance from the shaft bottom.

Jan 1, 1987

By J. E. Hawley, Y. Rimsaite, T. V. Lord

"IntroductionIN THE COURSE of. a spectrographic investigation of the platinum metal .content of various minerals in sulphide ores, the use of • fire-assay beads dissolved in gold-amalgam ( 1) was found suitable for the quantitative determination of palladium and platinum. Later work on platinum and bismuth-rich beads showed however, that these could not always be readily mixed uniformly in the amalgam. Accordingly another technique was sought which would allow the simultaneous determination of gold, silver, palladium, platinum, rhodium, and bismuth, the last .a common contaminant in fire-assay beads. The method evolved, which consists of dissolving fire-assay •beads in .lead, resembles in several respects the method of Scobie (2) in which silver was used. It has equally good sensitivity arid reproducibility, and allows the determination of silver as well as the other metals mentioned. The 'mutua1 standard' method of calculation (3a) is used to determine actual quantities present. This method has been applied to sulphide and arsenide minerals and •ores• of nickeliferous and non-nickelferous deposits• of both pre-and post Cambrian age, and, following a suggestion by Dr. G. S. Hume and the late Dr. H. V. Ellsworth, Geological Survey of Canada, has also been used for a peculiarly rich platiniferous uranium oxide ore from the Nicholson property, Lake Athakaska, Sask. More recently, the method has been .tested for the determination also of iridium and ruthenium and results indicate it may be applied, as• well to osmium."

Jan 1, 1953