Search Documents

By J. T. Norton, J. G. McMullin

E. R. JETTE*—The way this ternary was developed there are two directly determined points on each of the iso-thermals except the 700° isothermal, where I believe there is only one. How were the end points determined, and what was the basis for it? Whose work formed the basis for the silver copper line ? M. B. BEVER †—At most temperatures the authors determined three points of the isothermal line. For example it can be seen from Fig 3 and 4 how three points for the 600°C contour line were obtained. The authors took two additional points for each temperature from the copper-silver binary diagram contained in Hansen's volume on constitution diagrams. It is correct that the 700°C contour line is based only on one point in the ternary field which was found by a slight extrapolation of Fig 4. R. I. JAFFEE*—Are the tie lines representing phases in equilibrium parallel to the silver-copper boundary ? M. B. BEVER—Are you asking that as a matter of principle ? R. I. JAFFEE—I assumed that would follow from principle. I wonder if that is in accordance with the authors' ideas too. M. B. BEVER—I do not believe the authors obtained any information on the tie lines in the two-phase field. Of course, in the limiting case of very low gold contents the tie-lines approach to the silver-copper boundary, but generally in the two-phase field I do not think that the tie-lines have to be parallel to the boundary. E. R. JETTE—I am quite sure they do not have to be parallel. You cannot tell from this work in which direction they go. E. A. GULBRANSEN*—Were any pycnometric measurements made to check the lattice parameters of the alloys ? M. B. BEVER—I did not hear any-

Jan 1, 1950

By G. H. Montgomery

THE PROPERTY of Aunor Gold Mines, Limited, consists of eleven claims, located in Deloro township, approximately three miles southeast of the town of Timmins. Production began in 1940 and currently the mine is operating at a rate of 485 tons per day. GEOLOGY AND MINE DEVELOPMENT The ore zone at Aunor occurs in altered lavas bounded on either side by soft talc-chlorite schist, locally known as 'soapstone'. The zone has a strike of N.80°E, dips 60° North, and varies in width from 0 to 250 feet. Within this zone the main orebody has a westerly plunge, away from the No. 1 shaft area (Figure 1). The mine is developed by a vertical three-compartment shaft from surface to the 3,082-foot horizon. Working levels are spaced at 125- foot intervals from the 625-foot to the 1,625-foot horizon, from which to tl1e 2,125-foot level the interval is 250 feet.

Jan 1, 1957

By H von Blottnitz, A C. Keith

The influence of the life of a mine extends beyond its immediate vicinity both in geographic and temporal terms. Decisions around mine approvals are generally made based on economics, for the mine owner and immediate environmental and social impacts by governments and communities. The value from life-of-mine planning can also be viewed in a holistic frame across the entire value chain from mine to product user. This research examines the Carmichael Coal Mine in light of the holistic benefits and impacts along its value chain from the mine to relieving the lot of energy poor in India.CITATION:Keith, A C and von Blottnitz, H, 2016. Can Australian coal alleviate energy poverty in India – a case study, in Proceedings Life-of-Mine 2016 Conference , pp 52–56 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jun 28, 2016

By Stephen C. Tadolini, Thomas M. Barczak

Roof support systems, longwall shields in particular, have persistently grown in size and capacity for the past 25 years. Why is this? Is it a good thing or is it unnecessary? What are the consequences of this “bigger-the-better” design philosophy? Rarely do we see a “one size fits all” approach to roof support except when it comes to longwall shields, where the historical trend for new procurements is to simply purchase the highest capacity support you can buy. Does high capacity ensure failures will not occur? The answer is no! The highest capacity tailgate supports are typically the ones that fail the most often. What does this tell us? It tells us that there are fundamental aspects of support design and ground control that we still do not understand or recognize when designing a support system. This paper provides an interesting evaluation of these issues and proposes a different approach to support design that attempts to match the support performance characteristics to the ground behavior. Along the way, some of the old premises of support design will be discarded, and new “controversial” ideas developed. Thinking outside the box never hurt any industry. Mining has made it a common practice.

By L. B. Pankratz, R. Barany, W. W. Weller

Experimental determinations were made of the heats of formation at 298.15 ° K of cuprous ferrite and cupric ferrite ; the heat capacity of cuprous ferrite was measured over the temperature range from 50 ° to 298 ° K and the entropy at 298.15 ° K was evaluated ; the heat contents of cuprous ferrite and cupric ferrite above 298.15 ° K were measured to 1,500 ° K and 1,100 ° K , respectively . These thermodynamic values were combined with other pertinent data to obtain heat and free energy of formation values at high temperatures . The stability of the two ferrites with respect to their constituent oxides is discussed . Thermodynamic values are included for the decomposition of cupric ferrite to form cuprous ferrite , magnetite , and oxygen .

Jan 1, 1964

By Vivek Samu, Murthy Guddati

A new method called Effective Dispersion Analysis of Reflections (EDAR) was recently developed to effectively analyze the dispersive waves generated from lateral impact to piles. This paper presents the results of nondestructive length estimation of existing piles through EDAR. EDAR provides a new visualization method for analyzing wave reflections by transforming the response into the frequency domain thus eliminating the need to perform difficult peak picking in the time domain. In addition to being able to analyze dispersive waves, EDAR also incorporates the effects of radiation damping due to the surrounding soil leading to more accurate length estimates. Concrete filled steel tubes of different embedment depths were tested both in laboratory and field conditions. Length estimates obtained were within 10% error margins after careful analysis accounting for the presence of soil effects and effects from pile top reflection.

By Robert F. Droullard

The Bureau of Mines has investigated techniques of using gross alpha or beta detectors to continuously measure working levels. Both methods measure radioactive particulates collected on a filter paper using a constant airflow. Inherent-error studies indicate a value of about ±3 percent for the gross alpha method and about ±8 percent for the beta method in typical mine atmospheres. However, the beta method avoids problems associated with alpha detectors and is therefore more useful. Applications of these continuous working-level detectors include work area monitoring of exposure levels in underground openings, such as mines and caves, and calibrating personal dosimeters exposed over extended time intervals.

Jan 1, 1977

By M. Tsesarsky, M. Hazan, E. Gal

"Rock masses comprised of stiff inclusions in softer matrix are common in various geological environments. The heterogeneity and multi-scale nature of these materials make the evaluation of their mechanical properties a challenging task, which cannot be accomplished using conventional laboratory tests and composite mixture rules. We employ the homogenization method to estimate the mechanical properties of geological materials with inclusions. The homogenization method solves the equations of elasticity on the material (microscopic) scale for a unit cell subjected to unit strains under periodic boundary condition. The micro-scale elasticity equations are solved using the Finite Elements Method, and are in turn used to obtain the structure scale (macroscopic) material matrix.In this research, Finite Element models for unit cells with spherical and ellipsoidal inclusions were developed. Using the unit cells, a parametric study of the geometrical and statistical microscopic properties of the material composites was performed. The following parameters were studied: volumetric ratio, Young’s modulus ratio, size-distribution of inclusion and inclination angle of inclusions. The main purpose of the parametric study was to study the deviation from isotropy as a function of the aforementioned parameters.It was found that for volumetric ratio of 5%-40%, the deviation from isotropy increases, as the volumetric ratio of inclusions increases. For spherical inclusions, most of the cases studied exhibit quasiisotropic behaviour; whereas ellipsoidal inclusions exhibit considerable deviation from isotropy. The inclination of the ellipsoidal inclusions enlarges the deviation from isotropy (9% at random orientation and 26% at 0°)."

Jan 1, 2015

By Adrian Moore, Alan Richards

"It has been common practice to set blast vibration limits for structures using an “observational”approach whereby limits are set at a level based on observations of damage, or the lack ofdamage, combined with a tendency to further reduce the permitted level due to uncertainty. Suchan observational approach was used in the USBM RI 8507 to produce the frequency dependent‘Safe Levels of Blasting Vibration for Houses’ which has become a universal Standard for overthirty years."

Jan 1, 2013

By J. A. Roberson, Robert A. Rapp

From the observation of platinum wire marker movement in the oxidation of columbium at high lemperatures and low oxygen pressures, predonzinant cation diffusion in CbO, has been demonstrated. The Cu,0 molecule was used as an oxidizing species to study the nature of the porous scale and the location of the reduction site in the oxidation of colum-bium. The Cb205 scale contains microporosity and forms by alternate ionic diffusional growth and fracture. The oxidation of columbium at high temperatures and very low po, results in a relatively compact and protective Cb205 layer. THE observation of marker movements during oxidation is one means for the identification of the mobile ionic species in an oxide lattice. Previous marker experiments in the oxidation of columbium have all resulted in the markers being found on the outside surface of the Cbz05 scale. The Cr203 powder markers of Klopp et a1.,' the gold film marker of Kofstad and ~jijllesdal,' and the platinum wire marker of Cathcart et a1 .3 were found at the oxide/gas interface for oxidation temperatures ranging from 450" to 120O0C. However, in all experiments relatively high oxygen pressures were used. As discussed by Mrowec, even the interpretation of marker experiments in simple scales containing only one compound is not without ambiguities. In brief, it can be said that a marker may be found almost anywhere in the scale layer if the metal oxidizes by cation diffusion through the scale; the position of the marker depends upon morphological happenings in the scale. When considering marker movement in a polyphase scale one must proceed with extreme caution. For example, in the past (and present) work markers have never been found at the columbium-scale interface, and one might infer that the oxygen ion is mobile in CbO and CbO,. However, only trace quantities of CbO and CbOz have been present on any of the specimens, so no firm statement is justified on this basis. Despite previous experimental work, considerable doubt still exists concerning the role of the oxides CbO and CbOz in the oxidation of columbium. The identification of the mobile ionic species in CbO and CbOz from the observation of platinum wire markers was one goal of the present investigation . The linear kinetics of columbium oxidation at high temperatures (T - 1000°C) suggests that the Cbz05 scales which form on columbium are porous. From mercury absorption measurements on a Cbz05 scale formed at 500"C, Aylmore et al.' reported a minimum volume fraction of connected voids equal to 0.15. While these scales often appear to be quite porous when viewed in metallographic cross section, they are so brittle that metallographic preparation is likely to exaggerate any porosity originally present. In this investigation, porosity developed during the oxidation of pure columbium and present at the high temperature was detected by oxidizing specimens in sealed evacuated capsules containing large compacts of mixed copper and CuzO powders. wooda has demonstrated that the CuzO, or (CuzO),, molecule is volatile and that oxygen is transferred by the CuzO molecule from a Cu/CuzO mixture to materials having a greater affinity for oxygen. For each molecule of CuzO that is reduced at a sink for oxygen, two atoms of copper are deposited. Quantitatively, essentially all of the oxidation carried out by a Cu-Cu20 compact results from a displacement reaction involving the CuzO molecule. When a metal which oxidizes to form a porous scale is exposed to the CuzO vapor, the CUZO molecules are reduced in the pores leaving a deposit of metallic copper to mark the site of the reduction. This technique has the rather unique advantage that any copper-coated pores found in the scale are unambiguously related to the reduction site in the growth of the scale under consideration. Pores or cracks which form in a msition*- external to the reduction site or which occur as a result of cooling or handling of the specimen will not exhibit the copper deposit. EXPERIMENTAL PROCEDURE Marker experiments were made on columbium metal, and on pellets of CbO which had been pressed and sintered. Platinum wire markers (0.001 and

Jan 1, 1968

By Jari Aromaa, Antti Kekki, Olof Forsén

"The deposition of copper on inert substrate depends on the number of active sites that will react at certain overpotential. The critical overpotential depends on surface morphology, surface film resistance and additives on cathode surface. The effects of surface properties on copper nucleation and growth rates were studied for used stainless steel blanks from several tankhouses. The surfaces of the blanks were characterized with electrochemical and mechanical methods. Electrochemical deposition tests were done at current density of 300 A/m2 for 10, 30 and 60 seconds. The nucleation density and copper coverage were estimated using image analysis. The surface film resistance did not correlate with copper growth. Increasing surface roughness correlated with lower copper growth.IntroductionStainless steel cathode blanks in copper electrorefming are usually made of AISI 3 I6L type steel. They have a typical lifetime over 10 years. During use the surface will collect deposits and become rough due to wear and corrosion. These factors can affect the nucleation and growth of copper. The nucleation and deposition of copper on inert substrate depends on the number of active sites that will react at certain overpotential. The critical overpotential can depend on surface film resistance, surface morphology, and additives adsorbed on cathode surface.The deposition potential of metallic ions on a foreign substrate is usually higher than the deposition potential on the electrode made of the same metal due to crystallographic substrate/metal misfit [I]. If the substrate has traces of the depositing metal they will be preferential growth sites. For a smooth deposit a large number of simultaneous nuclei is necessary. However, excessive nucleation density can lead to porous deposits [2]. Surface films of good conductivity are needed for dense nucleation and small nuclei. On cathode blanks the number of active sites increases with increasing surface film conductivity [3-5] and/or surface film porosity [6]. On AISI 3 I6 L stainless steel a more resistive oxide has been found to limit favourable sites for copper nucleation and more conductive film promoted high-density copper nucleation [7]. Also Urda-Kiel et al. have concluded that thicker oxide layers on AISI 304 stainless steel resulted in lower nucleation [8]. Increase in overpotential or current density activates more and more of the potential nucleation sites and this can be seen as higher number of nuclei [9] or smaller average distance between nuclei [10]."

Jan 1, 2012

By Anuj Narang

Large-scale separation or flotation cells, used in the primary extraction in the oil sands industry, are integral parts of the overall process of bitumen extraction. Good regulation of the interface level between the bitumen froth and the middlings in these cells can result in a significant improvement in bitumen recovery and throughput, and heavily influence process economics. Automatic control of such industrial processes presents challenges such as multi-phase flow dynamics, variable process gain and time delays, poor quality of measurements and significant disturbances. This paper details a case study application of development of multiple models of the dynamics of the interface level and the design of model predictive controllers (MPC) for a separation cell process. A Model predictive controller (MPC) using linear models is designed and implemented in real time on an industrial separation cell. The industrial implementation results show that the MPC scheme provides significant benefits over the current operations which use a PID controller. The benefits include significant reduction in the variance of the interface level resulting in higher bitumen recovery and smoother downstream operation plus energy savings due to reduced underflow pump speed.

Sep 1, 2012

By Raymond S. Suglo

Increasing depths of mining coupled with the mechanization of most underground mining operations have led to growing complexities in the mine environments with the production of large amounts of gaseous and particulate contaminants. Over 100,000 lives have been lost due methane gas and dust explosions in coal mine workings in both the US and Canada since 1900 when the methane concentrations exceeded stipulated levels in some workings. There is therefore the need to constantly assess and evaluate the performance of the existing mine ventilation systems to maintain safe and acceptable mine environmental conditions in workings to meet the requirements of federal, state or provincial laws. This paper uses the results of continuous monitoring of methane concentrations conducted in selected development headings in coal mines in North America to assess the effectiveness of existing auxiliary ventilation systems in the control of methane gas concentrations in the headings. The results show that the average quantities of fresh air required to dilute, disperse and remove methane concentrations within set levels of one minute varied from 5.43 m3/s in Heading #11 (Condition 2) to 27.97 m3/s in Heading #10 (Condition 1) and this represented about 12 to 26% of the quantities required to dilute methane concentrations to safe levels within one minute under Condition 1 and 32 to 139% under Condition 2. The average dilution times in the headings studied were less than 8 minutes. The forcing efficiencies of the auxiliary systems in the headings studied ranged from poor to excellent implying that the auxiliary ventilation systems were capable of controlling the methane concentrations below statutory levels but may not be able to cope with large and unusual methane concentrations in the headings. This study is important to prevent methane gas and coal dust explosions in coal mines and thus avoid any loss of lives and property.

May 1, 2001

By Renato Ferreira Lima e Corrêa Pereira

Na manufatura de produtos metálicos, o forjamento é o processo de transformação a quente de materiais dúcteis, como aços e ligas, através de conformação mecânica efetuada com esforço de compressão por uma prensa, de modo que eles assumam os formatos desejados. Este processo normalmente é utilizado para produzir peças de formas complexas e com uma maior precisão dimensional de acordo com a especificidade exigida pelo cliente final. Para obter resultados de qualidade, foi necessária a implantação de técnicas de medição indireta de última geração, que proporcionam ganho de tempo e a redução de desperdício de energia e material, além de aumentar a segurança, reduzindo a presença de pessoas próximas aos materiais para medições manuais. O presente trabalho trata da criação de um sistema de visão que, por meio de análise de imagem, é capaz de coletar a medida do perfil de barras em uma Forjaria em tempo real, podendo ser utilizado durante a operação da prensa, para garantir que o material está em conformidade com o especificado. A execução do sistema em produção aponta que as medidas realizadas apresentam desvio máximo de 2mm em relação àquelas realizadas pelos operadores.

Jul 30, 2018

By M A. Rhamdhani, R Z. Mukhlis

Removing the ledge formation in the Hall-Heroult cell during the electrolysis process may significantly reduce the energy requirement of the aluminium production process. In the absence of the ledge, however, the sidewall-material types become heavily restricted since the cryolite is very corrosive at the electrolysis temperatures. This paper study the corrosion behaviour of sintered nickel ferrite, nickel aluminate, and magnesium aluminate refractories (as possible candidates for sidewall material) in molten aluminium and cryolite melts with various alumina content at 980°C. Immersion tests of refractories with various porosity were conducted to assess the suitability of the refractories in the corrosive environment of the electrolysis cells. Microstructural change of the refractory after immersion were analysed using secondary scanning electron microscopy (SEM). Sampling of the melts were taken at 0, 10 min, 30 min, and each hour up to 6 hrs, and subsequently analysed by Inductively Coupled Plasma (ICP) spectroscopy. Based on the projected concentration of the refractories constituents in the melts, it was predicted that the corrosion rate of NiFe2O4, NiAl2O4 and MgAl2O4 in cryolite with 11 wt per cent Al2O3 were 461 × 103, 1.03 × 103, and 798 × 103 cm/a, respectively. Much lower corrosion rate of 2.3 cm/a for NiFe2O4, 2.6 cm/a for NiAl2O4 and 0.3 cm/a for MgAl2O4 were predicted if the refractories in contact with aluminium melts. Erosion played an important role in the corrosion as the concentration of the refractory constituents in the melts were beyond its solubility limit. It is therefore crucial to increase the densities of the refractory and improve its wetting characteristics.

Aug 21, 2024

By Edwin B. Wilson, Joseph W. Leonard, Richard W. Borio

preparation of specification coals for the utility industry is approached from the standpoint of a cooperative effort with the power company to assure that the shipped product will be a noncorrosive coal. Selective mining, coal preparation, the use of additives, and coal blending are mine-site techniques proposed as means for upgrading corrosion-retarding constituents of utility coals (CaO and MgO) while, at the same time, reducing the concentration of those constituents of coal (Na20 and K,O) which cause corrosion. Data obtained from large-scale boiler testing in combination with bench-scale physical and chemical tests are used as a basis for the formulation of mine-site procedures to improve coal combustion utilization. Electric power generation remains the greatest market for coal in the United States. A major reason for this strong market has been the ability of the coal industry to supply a superior product for combustion while maintaining competitive prices. Now that the coal industry is engaged in intensive competition with nuclear power for future energy demand, it becomes ever more imperative that superior coal products are produced. One important problem when burning some coals is a liquid phase corrosive attack on boiler tube metal in the superheater and reheater areas of the furnace where steam temperatures may exceed 1050°F. In addition to causing power outages and high maintenance costs, corrosion is a continuing barrier to the future development of more efficient steam cycles which permit lower generation costs when using coal. Research methods of the past which have been directed at finding solutions which could be applied at the power plant site have been only partially successful and are generally costly. This paper contains a suggested --method of corrosion control through investigation of the problem at the source of the trouble—the coal supplier facility. It is proposed that mine-site pre-ventative procedures be considered as an effective means of cooperative corrosion control between the power company and the coal supplier. Economic justification must be applied to the individual situation. This paper is based on recent work by Combustion Engineering, Inc. and the Coal Research Bureau of West Virginia University under a contract from the Department of the Interior Office of Coal Research.',' Results which are of importance to this discussion may be summarized as follows: 1) The alkali minerals of coal (Na2O and K2O), as measured by an acid leaching process, can be related to corrosion rate in utility boilers. As these constituents increase in a coal product, its corrosiveness can be expected to worsen. 2) The alkaline-earth minerals contained in coal, reported as total CaO and MgO reduce corrosiveness 2s their concentration increases. 3) Naturally occuring, alkaline-earth-bearing materials, such as limestone and dolomite, may be added to a coal to reduce its corrosiveness. 4) Coals with very low iron contents tend to be less corrosive. These results provide the groundwork for examination of the system of operations which occur at the supplier facility from the seam face where mining is begun to the point of loading for shipment. The Mining System Fig. 1 is a cross section of one of the typical coal seams (designated coal A) that was boiler tested during this research program. This seam is overlain by material which consists primarily of a gray-black shale. In the lower third of this seam, there exists a thin rock parting of less than 4 in. in thickness which is consistent throughout the seam. The floor material is fireclay. In order to examine mineral distribution throughout this particular seam, the Coal Research Bureau collected a

Jan 1, 1971

By F. R. McDonald

The proton NMR spectra of 32 pyridines in two solvents, carbon tetrachloride and benzene-d6, are presented. The chemical-shift and differential-shift values are correlated with the substitutent position and with the solvent media. The ring protons and the protons on alkyl substituents are tabulated. The paramagnetic shift of the protons adjacent to the nitrogen is discussed, and a proposed structure for the pyridine-benzene complex that is consistent with the observed anomalous paramagnetic shift is presented. The utility of the data in the identification of pyridine compounds found in shale-oil naphtha is demonstrated.

Jan 1, 1971

By B. Friedrich, N. Anastasijevic, S. Stopic

The extraction of nickel from Serbian and Western Australian lateritic ore by sulphuric pressure acid leaching (PAL) has been studied. The following parameters were tested: stirring rate, acid to ore ratio, reaction time, pressure and temperature. These studies were performed with ore samples from the Rudjinci, Serbia and Silcrete, Australia, both belonging to the laterite-silicate group of deposits. An increase of the reaction temperature and the stirring speed at a fixed acid/ore ratio showed a positive influence on nickel extraction. The decrease of the oxidation potential with time correlated with the increase in Fe(II) in solution and nickel extraction as the reaction went to completion for both ores. The target values of 95 % Ni extraction and 60 % Co extraction were attained in 5 min at 250°C for the Serbian silicate ore, at an agitation rate of 1500 rpm, 10 % solids, and acid/ore ratio of 0.40. Under similar conditions only 60 % Ni, but 69 % Co could be extracted from the Australian Silcrcte ore due to different mineralogy. The nickel extraction was shown follow a diffusion-controlled reaction model.

Jan 1, 2004

By Patrick R. Atkins

Energy issues will have increasing impacts on decision making in all facets of society over the next few decades. Industrial users of energy and producers of products that affect energy use must be fully aware of the implications of their processes and products on the energy situation. This paper describes a model that has been developed for the aluminum industry that allows scenarios to be evaluated to gain improved understanding of possible implications for our businesses. A brief overview of the model is provided.

Jan 1, 2006

By Richard L. Rains

During this study in 1983, the U.S. Bureau of Mines examined one mine and five prospects in the Greenwater Valley Wilderness Study Area (WSA). No mineral resources were identified within the WSA. Principal mineral commodities in the WSA are gold and silver with minor lead, and zinc. Two properties have significance; sample analyses indicate the Salsberry Prospect may have gold-silver-lead-zinc resources, and the Graham Jem Mine may have gold resources. The likelihood for development is greatest at the Salsberry Prospect, although the only recorded production from the study area was from the Graham Jem Mine; in 1908 less than 1 ton of gold-bearing ore valued at $25,000 per ton was produced. Gold, silver, lead, zinc, and copper minerals in the WSA are associated with rhyolite dikes and quartz veins in Precambrian gneissic rocks, commonly concentrated in sheared zones along the dikes and veins. Although known to contain silver-lead deposits elsewhere, Precambrian Noonday Dolomite sampled inside the WSA contained no significant mineral values. Much of the WSA is covered by relatively unmineralized Tertiary and Quaternary volcanic rocks. The Bureau collected 140 rock samples at four adits, nine shafts, four trenches, and 33 prospect pits in the WSA. In 1983, 14 lone claims and one millsite within the study area were current. No patented claims, placer claims, or coal, mineral, oil and gas, or geothermal leases were in the WSA.

Jan 1, 1985