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By M. Misra

Improved liberation and flotation of kerogen from eastern oil shale were accomplished with high-temperature grinding and a1 so with the addition of fuel oil during the grinding stage. Liberation measurements indicated that possible coalescence and aggregation phenomenon of kerogen particles during grinding may reflect this behavior. Additionally, ultrasonic treatment of the rougher concentrate prior to cleaning improved the quality of separation.

Jan 1, 1984

By Dani J. Alldrick, Alastair J. Sinclair, Colin I. Godwin

"Abstract - The Stewart mining camp has a long history of precious and base metal mining. The camp is abundantly mineralized, with more than 200 widespread, varied, vein prospects, deposits and orebodies. These show wide variations in the mineralogy of ore, gangue and alteration assemblages, and wide variations in textures and structural settings. This report establishes the timing of the different metallogenic epochs and suggests a specific exploration application for systematic lead isotope analyses.Galena lead isotope ratios from a range of mineral occurrences indicate that all these varieddeposits formed during two main mineralizing events. Lead isotope data from the Stewart mining camp do not provide absolute ages for the formation of mineral deposits, but the relative distributions of data are consistent with dates determined in other studies. One ore-forming episode occurred in the Barly Jurassic and the other in the Middle Eocene. Both metallogenic epochs were brief, regional-scale phenomena. Sorne deposits from the younger mineralizing episode were em­ placed adjacent to or superimposed on the older deposits.Field and laboratory studies show that the two metallogenic epochs are characterized by different base and precious metal suites: Barly Jurassic gold-silver-zinc-lead-copper; and Middle Eocene silver-lead-zinc. Therefore, showings of different ages have different base and precious metal potentials and deserve different exploration emphasis. Lead isotope studies provide a reliable, cost-effective method for evaluating the age and commodity potential of small or recently discovered mineral showings and for setting exploration priorities on properties with several varied mineral occurrences . The determination of the age and metal potential of a prospect at an early stage of exploration may govern the urgency, intensity or even the necessity for further exploration work."

Jan 1, 1993

The primary use of coal in the US is for electric generation. The problems associated with the use of this vast amount of coal is the central theme of these sessions. The problems discussed include: production capacity, mining problems, coal cleaning, transportation, combustion, and various environmental problems, such as health effects of coal combustion, water and air pollution, and solid waste disposal.

Jan 1, 1979

By Rodrigo Rossi

Evaluating the field of artificial intelligence, it could be seen an increase on video analyses (or computer vision) usage, capturing information that would be difficult to get with other techs and reducing measurement error. After this research, it was presented to operational managers and the idea of applying it to monitor our industrial processes was born.

Sep 29, 2023

By H. Kenworthy

The investigations described in this report were undertaken to demonstrate, on a laboratory scale, the possibility of recovering several million pounds of tin plus tungsten contained in stockpiled and currently rejected slags from the Longhorn tin smelter at Texas City, Tex. At the same time, it was anticipated that the treatment procedures developed might be applicable to slags from other tin-smelting operations. Results of the laboratory work show that it is possible, by pyrometallurgical means, to separate the tin and tungsten into products of intermediate grade that may be returned to the smelter circuits for further upgrading. Several methods of treatment were investigated. The methods that proved effective were: Fusion reduction, chloride volatilization, sulfide volatilization, and carbide formation. Over 90 percent of the tin and tungsten could be removed from the slat by any of these methods. Each type of treatment has advantages and disadvantages, and it could not be determined from the small-scale work which method was the more meritorious. Tungsten and (in some types of treatment) tin-bearing products were diluted by iron, the separation of which will require additional studies. Prevention of a portion of the iron from reporting with the tin or tungsten is a distinct advantage and possibility that will require inure laboratory work to develop the needed techniques for its accomplishment. Tin products from single treatments of stag ranged up to 75 percent in tin content but were more generally under 35 percent. Tungsten products were usually under 15 percent; but segregated portions could be selected, at a sacrifice in recovery, that contained up to 50 percent tungstic oxide equivalent.

Jan 1, 1957

By Rae Mackay, Kaveh Ranjbar Pouya, Ali Tolooiyan

"A major part of Melbourne’s central business district is underlain by a very soft silty clay deposit known as Coode Island Silt (CIS). Due to the low strength of CIS, most construction in the region is based on pile foundation systems. Traditionally, the design of pile foundations is mostly based on empirical and analytical methods. However, numerical methods such as Finite Element Methods (FEM) can be utilised for more accurate estimation of the bearing capacity and deformation of pile foundation systems, especially in complex loading scenarios. Unfortunately, no systematic effort is made yet to calibrate a realistic nonlinear constitutive model to describe the geomechanical behaviour of CIS in a numerically based solution. Among the nonlinear constitutive models, the Hardening Soil (HS) model is an advanced hyperbolic model which accounts for the nonlinearity of stress-strain relationship as well as the stress dependency of the soil stiffness. In this study, the HS model is calibrated based on laboratory tests performed on CIS. Also, to validate the accuracy of the calibration, the wellknown cavity expansion theory is employed to model the CPT cone tip resistance (qc) in CIS, and results are compared against the measured CPT qc profile at the field.INTRODUCTIONA large percentage of world’s coastal areas are covered with soft marine clay deposits. Having very low shear strength and high compressibility, the alluvial deposits are known as one of the most problematic soil layers for the design and construction of infrastructure facilities. A major part of Melbourne’s central business district is underlain by a very soft silty clay deposit known as Coode Island Silt (CIS). Basically, there are two main solutions for construction in such weak soil conditions. One is the use of pile foundations transferring the applied load to deeper and stronger soil layers, and the second one is to employ ground improvement techniques such as using deep soil mixing columns to improve the bearing capacity of the soil. In both cases, a practical geotechnical design should incorporate both stability analysis and deformation analysis to achieve a cost-effective and reliable solution. Most of the classic solutions for stability analyses such as limit equilibrium analysis disregard the stress-strain relationship of the soil for the sake of the simplicity (Chen, 2007; Sokoloviskii, 1965). In a similar simple approach, most of the past studies of deformation analysis have been established on the basis of linear elasticity. However, it is well recognised that the soil stress-strain behaviour is highly nonlinear even at very small strains (Burland, 1989). Hence, for a precise deformation analysis of the foundation of important geotechnical structures, the application of advanced nonlinear constitutive models is extremely beneficial. Precise deformation analysis is essential as geotechnical designers have to predict the displacement of geotechnical structure and the adjacent soil as well as the induced displacement and forces to adjacent structures. This issue is more highlighted recently in the analysis, and design of highly important infrastructures as geotechnical engineers are facing new challenges in the analysis and design of infrastructures in congested areas. Rapid population growth, especially in the major cities all around the world necessitates the design and construction of more integrated infrastructure facilities. Consequently, geotechnical engineers should employ more advanced design approaches to address the new challenges in geotechnical engineering practice. Complicated geometries, different loading scenarios and the application of nonlinear deformation models which is believed to be essential for a precise deformation analysis, necessitate the application of numerical methods to satisfy most of the design requirements."

Jan 1, 1900

By Fabrício Domith Rodrigues, Marcelo Moreira Furst Gonçalves, Leonardo José Silva de Oliveira, Luiz Fernando Andrade de Castro

Eventualmente é necessário ajustar a largura de placas via processo de oxicorte. Contudo, o processo de corte convencional a frio não é recomendado para algumas qualidades de aço por gerar susceptibilidades às trincas na seção de corte. Para contornar a ocorrência de trincas no corte convencional foi desenvolvida e aplicada na Usiminas uma nova técnica de oxicorte em placas com base na utilização de duplo maçarico. Após otimização dos parâmetros de velocidade e posição dos maçaricos foi possível obter temperaturas da ordem de 200°C, homogeneamente distribuídas ao longo da seção de corte, favorecendo o ajuste dimensional sem trincas. Com a implementação industrial, verificou-se índices superiores a 85% de aprovação de placas e, consequentemente, o aproveitamento de placas que anteriormente não eram destinadas a geração de produtos laminados.

Oct 1, 2019

By K. L. Cashdollar, C. K. Man, J. R. Gibbins

Oxyfuel combustion is currently one of the principal technological options being considered for capturing carbon dioxide from pulverised coal power plants. In oxyfuel combustion, coal is burnt in a mixture of recycled flue gases and added oxygen instead of in air. In principle this yields a flue gas containing only carbon dioxide, water vapour and small amounts other impurities. Oxyfuel combustion is superficially similar to combustion in air, but there are inevitable differences. This paper describes ignition tests on pulverised coal suspensions using a suite of coals of different rank and from different countries of origin and over a range of oxygen and coal concentrations of interest for oxyfuel combustion. The ignition tests were carried out using the National Institute for Occupational Safety and Health (NIOSH) 20-litre explosion chamber. The purpose was to determine how easily the various coals ignite and burn in mixtures of O2 and CO2 compared to their combustion in air. The residual char volatile and ash contents for the ignition residues were measured using a thermogravimetric analyser (TGA), allowing Q factors (i.e., enhancement in apparent volatile yield due to higher heating rates and/or heterogeneous reactions) to be determined and compared. An ignition index has been derived from the explosion and char data. This index has been used to rank low volatile coals for ignition propensity in air. The results show that to obtain ignition and combustion comparable to that in air, the oxyfuel O2-CO2 gas mixture must contain over 30% O2. Keywords: CO2 capture, combustion, pyrolysis, oxyfuel.

By Larissa Rodrigues de Carvalho Rocha, Mauro Vivaldino Fernandes, José Eduardo da Silva Moreli, Beatriz Fausta Gandra, Adriano Cesar Carvalhido

No atual cenário siderúrgico, o prolongamento da campanha de um alto-forno tem sido prática usual em diversas empresas. Nesse contexto, a Usiminas tem realizado diversas ações de preservação dos altos-fornos, conciliando com a manutenção da competitividade. Particularmente, o Alto-Forno 3 da Usina de Ipatinga passou por duas trocas de staves, em 2015 e 2018, totalizando a substituição de 68 peças. No presente trabalho é apresentado o planejamento e a execução do retorno operacional após a 2ª troca de staves, destacando as contingências adotadas e lições aprendidas face às ocorrências que impactaram o cumprimento do cronograma previsto. Essa intervenção possibilitará a postergação da reforma para 2021, em alinhamento com as diretrizes da empresa e garantindo uma estabilidade operacional, fundamental para os cumprimentos e superação das metas.

Oct 1, 2019

By Thiago Alexander Heck

A indústria de máquinas e equipamentos hidráulicos está manufaturando produtos com tolerâncias de ajustes dimensionais cada vez menores, visando o prolongamento da vida útil e o alto rendimento de tais componentes. Nesta perspectiva, é notória a necessidade de identificar as principais fontes de contaminação existentes nos fluidos hidráulicos, a fim de controla-los. A partir da coleta de amostras de um óleo hidráulico que passa por uma filtragem nominal e de um óleo hidráulico que passa por um processo de filtração absoluta, foi realizada a contagem de partículas, análise por fluorescência de raios-x, análise microscópica ótica e análise por microscopia eletrônica de varredura, para estas amostras. Com base nas análises realizadas, foi possível constatar a importância do processo de filtragem absoluta na redução dos níveis de contaminação do óleo hidráulico.

Aug 16, 2017

By Dr. Calvin J. Konya, Anthony Konya

Blast violence has always been a criteria that has been analyzed without a quantitative approach relying on opinions of those viewing the blast and oftentimes does not transfer between open-pit mines, quarries, and construction projects. Added to this confusion is that on many regulate projects, such as U.S. Army Corp of Engineers construction projects, the definition of "flyrock" or violence can vary, and contractors must be able to meet this requirement. This project analyzed hundreds of blasts from various construction projects to develop a new metric to determine blast violence - the Violence Factor. If a blast is fired using 1.25" (32 mm) diameter product and a 10-foot (3 m) bench, vertical uplift of 60 feet (18.3 m) would be considered extreme and violent by any professional in the industry. However, a 100-foot-high (30.5 m) bench using 12" (305 mm) bulk product, having a vertical displacement of 60 feet(18.3 m)might be considered typical or non-worrisome. This is where violence factor is beneficial as itprovides a system of scaling the violence of a blast based on the bench height to give manager a keyperformance indicator (KPI) which is easy to monitor and can provide a large amount of information onsite-specific design variables for their performance on blasting and the end-results of the blast. The Violence Factor of a blast is an integer which is scaled to determine how high vertical uplift of a blast is compared to the bench height. This project analyzed numerous blasts to determine what blast design variables contribute to violence. This violence has also been shown to occur when a non-optimal breakage mechanism, cratering, occurs and the design criteria that lead to this cratering. Finally, this paper will present typical results of various levels of violence including backbreak, fragmentation, and muckpile configuration.

By K. S. Radcliffe

Results are presented for the first phase of an experimental program to study the feasibility of using acoustic velocity for predicting the state of stress in a rock mass. Compressional wave velocities were determined axially in cylindrical samples during uniaxial compression for several rock types conditioned in dry and water-saturated environments. Results indicate that in rocks containing compressible voids or cracks, substantial velocity change occurs with the application of stress in the lower (below 100 MPa) stress regime. The effect norm- ally is nonlinear, however, and diminishes to asymptotic values when cracks or voids become closed or with saturation. Empirical prediction equations were derived for each rock type by linear and nonlinear regression analyses, and correlation coefficients were calculated to determine the equations that best fit the stress- velocity data. The operational range for predicting stress using compressional-wave velocity appears to be within the range of vertical stress expected in most shallow to intermediate depth mining operations (less than 1,000 m). Based on the experimental results to date and theoretical considerations, it appears that the technology can be advanced to predict in situ stress based on acoustic P-wave velocity determinations in most mining situations.

Jan 1, 1986

This is the first publication in a projected series of reports on properties of commercial motor fuels pursuant to a cooperative agreement between the Cooperative Fuel Research (C.F.R.) Committee and the Bureau of Mines of the Department of the Interior. The report gives results of analyses in oil-company laboratories of sample of gasoline obtained from service-station pumps in 18 marketing areas by representatives of oil companies. These companies obtained the samples and analyzed them for their own information and supplied data from their laboratory reports to the Bureau of Mines for compilation and publication. History of Bureau of Mines Gasoline Surveys The following quotation from Report of Investigations 31624/ is included in this place for the information of readers who are not familiar with the Bureau of Mines gasoline surveys that have preceded the present report:

Jan 1, 1936

By M. C. Malamphy

A general description of the activities and results of bauxite investigation by The Bureau of Mines at its bauxite project in Saline and Pulaski Counties, Ark., has been given in Report of Investigations No. 4251. The factual data obtained during the project are reported in a series of Reports of Investigation beginning with No. 4251, of which this is the fourth. The data are accompanied by maps showing the location of holes drilled and the deposits developed. Each area upon which work was done is reported by half townships. Each bauxite deposit investigated was assigned a name and a number for ready reference and identification, and its location and name are shown on the appropriate half-township map. The description of each half township is followed by a description of each deposit developed in that half township. The 14 half-township maps and 77 detail maps of the bauxite deposits in this series of reports give the locations and numbers of all the holes drilled on the project except the deep holes drilled to test the geophysical anomalies. The locations of those holes show on Figure 13 in Volume 1. The descriptions of the deposits developed are followed by complete detailed logs of the drill holes. Many of the widely spaced exploratory holes did not discover bauxite of minable thickness and grade. The pertinent information obtained from the widely spaced exploratory drill holes has been summarized and tabulated, and a table for each half township-is given with the discussion covering that area.

Jan 1, 1948

By John D. Hanks

INTRODUCTION Chevron's Uranium Mill is located near Panna Maria, Texas; 70 miles southeast of San Antonio. Designed by Kaiser Engineering, the Mill will process a nominal 2500 dry T.P.D. of uranium bearing ore containing 15% uncombined moisture. Earl Torgerson, San Mateo, California, is the consulting metallurgist on process design. Feed to the plant consists of a mixture of high, medium and low grade sandy day ore; the average grade of the ore will be 0.7% throughout the life of the project. The ore is delivered to the mill via truck and stored by type in individual piles on a flat storage area. The ore is fed by conveyor to a semi-autogenous grinding mill. The SAG mill discharge slurry is pumped either to a storage tank or to the first of five mechanically agitated leach tanks where both H2SO and NaC103 are added. Following leaching, the slurry is mixed with thickener No. 2 overflow before being pumped to a six-thickener, countercurrent decantation circuit where the solution containing uranium is separated from the leach residue. The residue is washed essentially free of solubilized U308 values at the sixth thickener and discharged to an adjacent tailings pond. The first thickener overflow, containing approximately 0.4 grams U308 per liter, is filtered for clarification and sent to the liquid ion exchange (solvent extraction) section. The pregnant aqueous solution is mixed with organic solvent containing amine on which the complex uranyl sulfate ions are absorbed. The immiscible aqueous and organic solutions are mixed and separated in each of the four stages of solvent extraction. The final pregnant organic is directed to a stripping section. A strip solution containing (NH4)2S04 (ammonium sulfate) and NH4C1 (ammonium chloride) is contacted and separated from the organic in each of the four mixer-settler units. The strip solution is mixed with NH3 and the uranium precipitates along with trace amounts of sulfate, chloride, and ammonia. After washing in a thickener, the uranium precipitate or yellowcake is centrifuged and dried in a multiple hearth roaster. Overflow from the yellowcake thickener is recycled back to the stripping section of the solvent extraction circuit. The dried yellowcake concentrate contains more than 98% U308; diluents include H20, ammonia, chloride, etc.. Impurity concentratons in the product are sufficiently low, after drying, to permit direct shipment to refinement installations. ORE RECEIVING Ore from one or more mines will be stored on a pad adjacent to the uranium processing mill. Ore stored in the area may total 200,000 tons or more, which is equivalent to over a two month treatment reserve for the mill. In addition to providing surge capacity, the proposed storage facility permits natural oxidation of the ore and affords an area which, in turn, improve plant U308 recovery and reduces consumption of oxidizing reagents. The uranium bearing ore is segregated at the storage area into several distinct types. One group can be identified by its sandy, clay-like matrix and will be distinguished by its U308 concentration of high, medium, or low. Other ores contain substantial quantities of carbonaceous shale, typical of ore in the area. Feed is recovered from any one or combination of piles, in accordance with operating requirements and recovery factors. The run-of-mine ore, at 15% moisture, is transferred to a stationary, 24-inch by 24-inch grizzly. Undersize material falls into a 280-ton surge hopper located below grade, while oversize material is removed for preliminary size reduction. A sump-pump is located at the reclaim hopper to recover excess mositure and ore spillage for processing. Plant feed is continuously drawn from beneath the hopper at an average rate of 120 tons per hour by means of an apron feeder. The hopper is equipped with a low level safety system to protect the apron feeder assemble. The ore is transferred to a belt conveyor, elevated and discharged into a semi-autogeneous grinding (SAG) mill. Water addition at the discharge point is automatically controlled by a feed rate, moisture analyzer system located on the belt conveyor. GRINDING Minus 24-inch ore, at a rate of 120 mosit tons per hour and cyclone underflow at a rate of 137 moist tons per hour are combined with a controlled 186 gallons per minute fresh, warm plant process water. The mixture, at an average 68% solids, is fed to the SAG mill. The viscous mass is subjected to grinding at a temperature moderately above ambient resulting from use of the 140ºF well water. The 16.5'x5.0' Marcy Mill is driven by a 500 H.P. A.C. Motor. The mill will rotate at 73.4% of critical speed or 14.06 R.P.M. Eight percent of the mill's volume will be occupied by steel grinding balls; 22% by pulp. The mill is designed to rotate in either direction, in order to obtain maximum lifter and liner life. The SAG mill is equipped with a trommel having ½ -inch slots for removal of oversize material at its discharge and the large or oversize material is collected and either recirculated periodically or discarded. The undersize slurry is diluted to 64% solids with the addition of hot well water or mine water to the mill discharge sump. The flow is automatically controlled utilizing data from a gamma density meter. The slurry from the mill discharge sump is pumped to hydrocyclones to classify the particles. Underflow from the cyclones, at 80% + 28 mesh, is recycled to

Jan 1, 1979

By S. A. N. Sheya

The U.S. Bureau of Mines performed batch equilibrium contact experiments to examine the ability of activated coconut-shell carbon to adsorb various metal cyanide complexes. Tests were also conducted to determine the effect these cyanide complex impurities might have on the adsorption of gold by the activated carbon. Metal cyanide species included in the investigation were antimony, arsenic, cadmium, calcium, cobalt, gold, iron, mercury, nickel, silver, thallium, and zinc. Tests were made over a pH range of 6.4 to 12.5. The carbon exhibited a preference for gold adsorption over other metals present in solution. In the absence of gold, the metal cyanide complexes were adsorbed; adsorption generally decreased with increasing pH. However, calcium and thallium adsorptions increased with increasing pH, while arsenic and iron were not adsorbed at any pH.

Jan 1, 1989

By R. Ward Stahl

This publication is a revision of Report of Investigations 5363 updated to reflect the improvement in fire protection at selected coal mines and contains suggestions on what may be considered good fire protective equipment, suggested methods of organizing the attack on fires at various locations underground, and helpful hints on testing and evaluating firefighting facilities.

Jan 1, 1968

By D. Van Tonder, C. Edwards

ABSTRACT Solvent extraction is used in many acid leach uranium circuits to upgrade and purify the uranium-bearing solution prior to final product precipitation. A number of strip options are available to recover the uranium from the loaded organic. This paper compares seven of these options on the basis of typical capital and operating costs for the solvent extraction circuit and downstream uranium processing and also considers other related issues. The aim is to provide an objective comparative assessment of these options that could be used as a qualitative guide in process selection or improvement.

Jan 1, 2013

By J. B. Davis

Isotope analyses distinguish biogenic sulfur ores from non-biogenic ores, but do not distinguish bioepigenetic from biosyngenetic ores. Sulfur deposits of salt dome caprocks and of bedded Permian evaporites of west Texas, however, are clearly bioepigenetic. Anhydrite, introduced by salt diapirs into geologically younger sediments, is converted biogenically to sulfur and calcite in the presence of petroleum; for example, in Challenger Knoll, a salt dome at a water depth of 3600 m in the Gulf of Mexico. Bedded evaporites of west Texas in association with petroleum show an obvious epigenetic replacement of the anhydrite layers by biogenic sulfur and calcite

Jan 1, 1978

By Peter Faust, Peter Hubbard, Kenichi Soga

The European Federation of Foundation Contractors (EFFC) and The Deep Foundations Institute (DFI) have set up a task group to compile a Guide for Working Platforms. The first edition of this Guide has been published in January 2020. The aim of the Guide is to provide reliable methods for design, testing and verification of working platforms for construction equipment, especially in the deep foundation industry where track loads can be excessive due to the nature of its operations. The Guide has identified areas where knowledge is limited. Actual track pressure and its distribution along the length of the tracks is still not well researched. Current recommendation provided in EN 16228-1 are believed to be overly simplified and may lead to conservative requirements for working platform thickness. This paper presents results of a series of field tests where the actual track pressure of a large drilling rig during operation was measured in real time together with the deformation of the working platform. Embedded, distributed fiber optic sensing (DFOS) at different depths throughout the platform allowed for a three-dimensional evaluation of the platform deformation throughout the entire operation. Results will help to develop more reliable recommendations for future safety requirements of working platforms for deep foundation equipment.

May 1, 2022