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By M Safa

Addressing deficiencies and defects that occur during construction projects is costly and time consuming. The manual quality assurance programs currently used in the industry have certain limitations, including human error and lack of consistency. Hence, there is a need for integrated electronic models that employ new technologies and methods. This research introduces an integrated construction quality control system that has the potential to improve quality management processes in the construction field for piping construction, which is a complex process often requiring rework. The proposed integrated system relies on data collected from construction sites using photogrammetry and laser scanning, which is then used to compare actual work performed to that designed. The proposed system aims to improve the promptness and accuracy of quality assurance processes, in particular dimension measurements, by avoiding human error and integrating defect detection and quality management. The use of this system has highlighted some of the limitations during data fusion and acquisition process, which are highlighted in this paper. These aspects must be considered to increase the reliability of the acquired information.

Aug 1, 2013

By M. Zamalloa, P. J. Mackey, P. Coursol, Y. Prévost

"Over the last decade or so, the availability of commercial thermodynamic modelling packages, such as FactSageTM, have been utilized to help the plant optimize slag chemistry and to minimize slag handling issues that can arise, such as those due to a process upset, for example, by undue feed variability. This paper illustrates an extension of the application of this software in examining a large range of NCV operating parameters, such as the %Fe/SiO2 ratio in the slag and the level of minor gangue components in the slag including CaO, Al2O3, ZnO, MgO, and PbO. The conditions influencing the slag liquidus range of NCV slag are discussed with respect to the overall process chemistry.Given that a sufficiently low %Fe/SiO2 ratio is used in NCV slag, most components such as CaO-ZnOPbO- Al2O3-MgO, in small concentration, all contribute to lowering the NCV slag liquidus. Considering the present level of these minor components, the NCV can operate consistently at 1200°C if the %Fe/SiO2 is between 0.6 and 0.8 in the slag. Using the type of phase diagrams presented in this paper, it is possible to develop different Noranda reactor/Noranda converter operating strategies adapted to the feedstocks available at Xstrata mines/plants or from other sources. The NCV is unique in that a fayalite-based slag is employed for high-efficiency continuous converting with excellent operating results."

Jan 1, 2007

By I. Thobadi, C. Pawlik, K. Bisaka, S. Mokoena, M. Erwee

The PyEarth™ process developed at Mintek has been demonstrated successfully at pilot scale. Nine tons of ore containing 2.3 mass % of total rare earth oxides (TREO) from a dormant mineralogically complex iron-rich ore deposit, was subjected to a concentrating smelting step in a 200 kW DC open-arc pilot furnace and the rare earths from the resulting slag were extracted via a hydrometallurgical route. This ore deposit is practically not amenable to extraction by conventional methods. The testwork results proved that the PyEarth™ process was able to optimize the extraction of rare earths while minimizing waste through the removal of iron as a saleable iron alloy. Reduction of iron to the alloy in the smelting step was found flexible, efficient, and controllable, while rare earths were left virtually unreduced in the slag phase. The slag chemistry is selected to optimize both the smelting and leaching performances as well as the alloy composition. Leaching of the resulting slag was found possible and most efficient in hydrochloric acid amongst other lixiviants tested.

Jan 1, 2017

By J. U. MacEwan

Introduction The equilibrium between copper, zinc, and chlorine may be considered as the simultaneous equilibrium of the two separate chemical reactions of formation of the stable chlorides of copper and zinc at the temperature of the reaction i.e., l440°K. (1,167°C., 2,133°?F.)§ [Zn(g) +Ciz(g) ZnCl2z(g). ... (1) ] [2Cu(l)+Cbi'g) Cu2Cl2(l 1 ....... (21 ] Subtracting, [Zn(g) +Cu2(Clz(l i ZnClz(g) +2Cu!l) ... . (3) ] If this reaction is carried out with a copper-zinc alloy at some constant temperature above the melting point of brass, and at a total pressure of one atmosphere, the equilibrium concentrations obtained will depend on the free energy decrease .of the reaction as written in (3) and on the activities of the various components in. the reaction mixture. If the equilibrium is examined from the point of view of the phase rule, it is a three-component system, and if it exists in two phases (liquid and gas) it will have three degrees of freedom. If the restrictions of constant temperature and pressure are imposed, the degrees of freedom are reduced to one. This means that, in a two-phase system under these conditions, each different alloy phase will be associated with a gas phase of constant composition.

Jan 1, 1951

By Douglas R. Piteau

"Assessing the stability of a slope cut in rock is basically a problem of engineering geology - geology, because it involves a sound understanding of the important aspects of geology, such as geological structure, ground water, weathering and other natural phenomena, which all relate to or exist in a geological environment, and engineering, in that quantitative evaluations and calculations are necessary, these being based on mechanics and relating to the strength of the geological materials and the forces causing instability of the slopes. The engineering geologist must make every attempt to. provide, in a quantitative way, information on those geological factors which are necessary for making calculations of the probable stability of the slope. These include numerical assessments of quantities relating to the characteristics of structural discontinuities, rock types, topography, hydrogeology, tectonic history and other environmental factors. Based on the development and extension of these general principles, both preliminary and final slope stability studies of some open pits in South Africa, Swaziland and Zambia have been conducted. Some of the basic concepts and techniques developed to carry these studies out are described."

Jan 1, 1972

By L Gill

The four basic types of electric motors -squirrel-cage, wound rotor, synchronous and D.C. -are de-scribed, with particular reference to speed-torque characteristics. The three classifications of squirrel-cage motors, C.E.M.A. B, C and D, are compared, and methods of selection for specific drives are outlined. Wound rotor and synchronous motors are covered from the viewpoint of construction details, methods of operation and control required. The application of these motors to crushers, conveyors and ball mills is described and reasons for their selection are given. The application of D.C. motors to haulage equipment and mine hoist drives is included, and the basic principles of a variable voltage drive are illustrated. Efforts have been made through-out to provide specific examples of motor selection, with particular reference to the mining industry. THIS paper will attempt to answer the question -"which motor should be used for a specific drive?" Although it is impossible to cover the complete subject of electric motor application here, we hope to give some idea of the types of motors available and why certain types are used on specific applications.

Jan 1, 1963

By R. H. Nafziger

A novel process has been developed for preparing directly workable steel ingots from prereduced iron ore pellets by a two-stage process. The pellets are continuously charged into an electric arc furnace, where molten metal is separated from the gangue. The molten metal flows out of this furnace through a hollow nonconsumable graphite electrode immersed in a molten flux in an electroslag furnace. The molten metal solidifies on a continuously withdrawing base plate to form the ingot. A variety of standard carbon and alloy steel ingots . free of porosity , were produced using suitable decarburizers and ferroalloy additions. Some advantages of the two-stage process include: (a) consumable electrode fabrication is eliminated; (b ) no expensive deoxidizers are required; (c ) the uncontaminated electros lap flux can be reused; (d) energy consumption averages 25% less than in a conventional electric arc - electroslag operation ; and (e) the operation is continuous.

Jan 1, 1977

By Sh. Karimidorabati

In the construction industry, project changes constitute a major cause of delay, disruption, cost increases, poor quality and unsatisfying performance. They are also known as a main factor of litigation between the owners and constructors. Construction projects are essentially process-based, and with the critical role of Information Technology (IT) in this industry, projects, especially mega projects, are being managed remotely. The volume of data and documents, such as Requests For Information (RFIs), different types of Change Requests (CRs) and Project Change Notices (PCNs), being transferred and exchanged amongst the stakeholders of a project is considerable. The circulation of these documents amongst project stakeholders still heavily relies on two methods or levels for management of change process; Conventional (fully paper-based, Faxes, Snail mails) and Electronic or semi-automated (Email, Internet, PDF files). These two methods are dependent on human discipline to follow specified processes which often break down because of human nature. This creates serious compliance problems. It is hypothesized here that fully that automated process-based management of change can lead to better compliance, more efficient management of change, and reduction of time and cost of data exchange. An approach of doing this is presented in this paper. Ultimately, its impact should improve project performance. Conclusions are presented on time savings and improved compliance.

Aug 1, 2013

By C. W. Drury

It is practically fifteen years since stellite was first introduced into industry, and since then the progress made in its manufacture has been so rapid and the number of successful applications so varied that it was considered a review of the more important phases would be of general interest. Stellite is a cobalt-chromium-tungsten alloy, containing approximately 2. 75 per cent carbon. The high percentage of carbon is necessary for the requisite hardness and resistance to wear at ordinary temperatures, whereas the tungsten is essential to impart hardness at a red heat. Chromium imparts hardness and strength, and cobalt renders the alloys more resistant to oxidation. The metals cobalt and chromium are completely soluble in all proportions, both in the liquid and solid state, the equilibrium diagram showing a minimum in the solubility curve at approximately 50 per cent cobalt and l,340°C. Cobalt and tungsten are completely soluble up to 40 per cent tungsten, which is beyond the limit of the; tungsten content of stellite alloys. In the presence of carbon, carbides are formed, which are essential in stellite possessing good cutting or wearing properties.

Jan 1, 1930

By S. Makni, S. Koppalkar, A. Bouajila

ABSTRACT This paper briefly reviews the gravity recovery between conventional and centrifugal gravity separators. The advantages of semicontinuous gravity separators will be discussed, as will techniques for upgrading the gravity concentrates. The research efforts in optimizing semicontinuous gravity separators will be recalled. An innovative gravity circuit for eliminating or minimizing the use of complex processing schemes will be reviewed. Ongoing gold gravity research has revealed that gold particle shape transformation is one of the main factors explaining the lower recoveries of the plant units. Efforts to devise possible remedies for improving plant gravity recovery will be discussed.

Jan 1, 2013

By F. Moraw

The use of redox fuel cells in which oxygen is replaced by other oxidants such as ferric ions can have significant advantages [1-3]. For example, the cathodic reaction rate (e.g., exchange current density) can be increased by several orders of magnitude compared to the oxygen reduction reaction, and platinum group metal (PGM) catalysts are not required. As a result of the higher aqueous solubility of the oxidant in a redox fuel cell compared to that of oxygen the rate of mass transfer (e.g., limiting current density) is greater by several orders of magnitude. The redox fuel cell can achieve high efficiencies and has other fuel cell advantages. The main issue with the redox fuel cell cathode is the regeneration of the oxidant where low conversion efficiencies are achieved even with platinum group metal (PGM) catalysts. In the work discussed here the Fe3+/Fe2+ redox fuel cell cathode is characterized over a range of electrolyte concentrations and operating conditions, and electrode materials. Cyclic voltammetry and electrochemical impedance spectroscopy are mainly used for electrochemical characterization and mechanistic determination of the cathode redox couple. Further characterization with selected compositions and materials is done in a redox fuel cell (hydrogen - Fe3+/Fe2+). The mechanism and the advantages and disadvantages of the fuel cell redox cathode are discussed with respect to other approaches and other redox couples.

Jan 1, 2005

By M. Behrouz

Thermal power plants convert thermal energy due to nuclear reactions or the combustion of coal, gas, heavy oil, or some other hydrocarbon to electrical energy. They consist of a variety of equipment, such as boilers, turbines, generators, cooling towers, and auxiliary equipment. Any factor that affects the equipment efficiency affects the overall efficiency. Analysis of the cooling tower and raw water using the Langlier Saturation and Ryznar Stability Indices showed that the cooling water at Sarchesmeh was slightly scaling with respect to silica. Cold lime softening was found to be a cost-effective method to produce cooling water with adequate properties to reduce the cooling water make up from 85 to 70 m3/h and blow down rate from 35 to 20 m3/h.

Jan 1, 2007

By K. D. Bulin

"An interesting brief history review of shovels as the primary excavating tool will permit the reader to see that immeasurable development and resources have preceded the shovel excavators which today are used extensively throughout the mining industry. With this as a background, the shovel manufacturer has the ability to utilize his resources best in those areas of shovel development in which the maximum benefits of increased reliability, performance and ease of maintenance will improve the operating rewards to the user of the equipment. The author explains the function of the shovel as a part of the material handling system. A detailed description of those areas of the shovel in which the most recent developments and major improvements have been implemented in the manufacture of the shovel excavator arc included."

Jan 1, 1973

By Quenton Johnson, W. A. Gough, David Carr

"This paper describes the application of the BrainWave Model Predictive Controller (MPC) and Advanced Control Expert (ACE) Advanced Supervisory Control System on the SAG Mill, Ball Mill, and Rougher Flotation cells for a new gold processing line at the Oceana Gold - Haile Gold mine in Kershaw, South Carolina. For this project, ANDRITZ supplied the control system design and programming, operator-training simulator and advanced control. The advanced control was tested against the IDEAS™ dynamic simulator, and commissioned during the startup of the processing plant to help achieve target production as quickly as possible. Operators were able to run the equipment in a consistent and optimized manner from an early stage of the plant operation, increasing efficiency and profitability. MPC is able to reduce process variability beyond the best performance that can be obtained with conventional Proportional Integral Derivative (PID) control methods. MPC is able to optimize the control of processes that exhibit an integrating type response in combination with transport delays or variable interaction, which are characteristic of many gold processes including SAG mill weight control and Flotation cell froth level control. The experience and benefits of applying MPC during the startup of a new gold processing plant are presented in this paper.INTRODUCTION Mineral processing operations present many challenges for automatic process control due to variations in unmeasured ore properties, material transport delays, and non-linear response characteristics. Advanced process control technologies such as expert systems and multi-variable model predictive controllers are often used to improve the control of these processes to increase productivity and recovery efficiency. Typically these systems are applied after the mine has been in operation for a period of time. For this project, a complete dynamic process simulator was developed using the IDEAS platform for the purpose of training operators before the plant was constructed. Operators were able to become familiar with the process and the control system in order to become proficient in the use of the controls before the plant was ready to start. They were able to practice abnormal condition management including startup and shutdown of the process using the simulator and develop complete Standard Operating Procedures (SOPs) for these situations. The simulator was also used to test the control system functionality and operator Human Machine Interface (HMI) configuration to reduce errors and improve the performance of the control system during plant start-up."

Jan 1, 2017

By O. A. Ojo, N. Esmaeili

"The effects of brazing and use of composite powder mixture as interlayer material on hot corrosion resistance of brazed IN738 superalloy were studied. Brazing was observed to result in significant reduction in the hot corrosion resistance of the superalloy. However, application of composite powder mixture, which consists of additive superalloy powder, enhanced the hot corrosion resistance of brazed samples. It is also found that although the use of composite powder mixture increased hot corrosion resistance of brazed alloy, if the additive powder completely melts, which is possible during brazing, it can significantly reduce the hot corrosion resistance of the brazed joint. Elemental micro-segregation during solidification of the joint with completely melted powder mixture produces chromium depleted zones and consequently reduces hot corrosion resistance, since a uniform distribution and adequate chromium concentration is necessary to combat hot corrosion. This has not been previously reported in the literature and it is crucial to the use of composite powder mixture for enhancing the properties of brazed superalloys.INTRODUCTION Superalloys have been developed in response to the increasing demand for materials with higher resistance to corrosion and creep and also with higher mechanical strength at higher temperatures (Smith, 1981). Ni-base superalloys are predominantly used in manufacturing hot sections of gas turbine engine components. This is due to their high strength and corrosion resistance in extremely high temperature service environments which is typical for hot sections of gas turbine engines (Miglietti, 2009). The continuous demand for higher efficiency and output has resulted in the use of higher operating temperatures and gas pressure in modern gas turbine engines (Jahnke & Demny, 1983). Consequently, this has caused thermal and mechanical stresses which result in severe degradation and damage of gas turbine engine components due to creep, fatigue and hot corrosion (Zhang, Feng, & He, 2006). The decision to replace or repair damaged parts depends on the overall repair cost and expected life of the repaired components (Jahnke & Demny, 1983). However, in most cases, it is more cost effective to repair damaged parts rather than use a full replacement."

Jan 1, 2017

By C. H. Hopper

THE gold orebodies of the Matachewan Consolidated mine are of particular interest geologically because of their odd shapes, their apparent lack of connection one with another, and the fact that they occur in a number of different formations. All of the orebodies exhibit a similar fracture pattern and the areas of fracturing appear related to the local folding. However, the lack of either horizontal or vertical continuity suggests additional controls not yet discovered. The question of origin, so ably discussed by H. C. Cooke in 1919, will be reviewed in the light of the additional evidence uncovered since his examination of surface trenches twenty-four years ago. The Matachewan Consolidated mine, with its neighbour, the Young-Davidson mine, is in Powell township, 25 miles by road northwest from Elk Lake, 30 miles west of Kirkland Lake, and 45 miles southeast of Porcupine. It may be considered as being on the westerly extension of the Kirk-land Lake sedimentary belt, where the rock column is markedly similar. There is no similarity in structure, however, for great ore-bearing shears and faults simply do not occur at Matachewan. Rather may it be said that the region, under stress, failed in isolated brecciated patches, some of which make up today's orebodies. The mine currently treats 1,000 tons a day of porphyry ore averaging 0.10 oz. gold per ton. It started operations in 1934 on greenstone ore, and the mill then treated 150 tons a day of ore averaging 0.23 oz. gold per ton. Total production to the end of 1941 has been 929,484 .tons averaging 0.160 oz. gold per ton.

Jan 1, 1942

By R. Yost

"This paper describes a case study that illustrates how detailed geological engineering results were communicated to address a range of stability challenges in a producing mining environment. Instead of using standard geological engineering terminology, findings and recommendations were communicated as mine design options and mining responses to accommodate possible slope instabilities and associated risk. The resulting medium- to long-range mine plan integrated the potential slope instabilities and associated mining responses to provide a higher probability of planned resource extraction. It also reduced the potential for long-lasting production and processing delays.RÉSUMÉ Cet article décrit une étude de cas illustrant l’intérêt de la communication de résultats détaillés de géologie appliquée pour résoudre un éventail de difficultés relatives à la stabilité dans un environnement minier en production. Plutôt que d’utiliser une terminologie classique de géologie appliquée, les résultats et les recommandations ont été communiqués sous forme d’options pour la conception d’une mine et de réponses dans le contexte minier permettant de surmonter les éventuelles instabilités des pentes et les risques associés. Le plan de mine sur le moyen à long terme qui a résulté intégrait les instabilités potentielles des pentes ainsi que les réponses connexes dans le contexte minier afin de renforcer la probabilité de l’extraction des ressources prévue. Il réduisait également la possibilité de retards durables dans la production et le traitement.INTRODUCTIONSlope failures in an active mining operation are unscheduled but expected events, in the sense that the geotechnical design often assumes the potential for slope failure but cannot predict exactly when a failure will occur. Unfortunately, the geotechnical engineering cycle—characterization, slope design, displacement monitoring, instability management, and failure remediation—that is necessary to manage slope-failure risk is not always well known or understood outside the geotechnical engineering profession. The first introduction many personnel have to geotechnical engineering is when a slope failure starts to develop and appears to threaten the safety and livelihood of their workplace.At that point, the task of communicating the risk management of slope failure falls to the geotechnical engineer, who must summarize analytical methodology, design concepts, monitoring trends, and analysis results, frequently to an audience with limited exposure to the geotechnical field. All too often, the response has been to present a risk-management plan in the vernacular of geological engineering— using terms such as factor of safety (FOS), pore-pressure reduction, and slope unloading—instead of expressing the problem and solution in more readily understood mine production terms."

Jan 1, 2017

By SANDVIK WHITE

The mining industry produces approximately 4-7% of global greenhouse gas (GHG) emissions. It is fundamental for mining operations to take immediate sustainable action to actively contribute to an emissions-free future for the next generations. The mining industry has traditionally relied heavily on diesel technology and transitioning to more sustainable solutions requires change management to drive cultural acceptance and new product development. Sandvik was interested to find out the lifetime emissions of a single drill rig and to compare similar application diesel and BEV drill rigs with same use profile to each other. That led the calculation and pondering towards comparing different countries and mine sites as well

Jan 1, 2023

"Ore deposits containing rare earth elements normally contain small amounts of the radioactive elements thorium (Th) and/or uranium (U). These are the naturally-occurring isotopes U238, U235, and Th232 (and associated decay-series daughter products) that are ubiquitous in nature, and that contribute a small percentage of the natural background radiation exposure encountered by humans. The presence of these radioactive materials in the ore deposit creates potential hazards to human health and the environment that must be dealt with properly in the mining, processing, and refining of the ores, as well as management of waste streams and residues. This paper presents an overview of the environmental and safety issues associated with U and Th, with particular emphasis on rare earth mining, processing, and refining projects; the regulatory approaches followed to ensure that rare earth deposits are developed, operated, closed, and decommissioned safely; and the development of information during the project predevelopment work and permitting processes that feed into the design, operation, and closure of tailings impoundments and milling/separation/refining facilities. Case studies will be presented subject to the availability of relevant public information. INTRODUCTIONNearly all ore deposits containing economically-recoverable rare earth minerals also contain small amounts of the radioactive isotopes for the elements thorium (Th) and/or uranium (U) and their associated radioactive decay products. Therefore, the handling and management of these materials in mining and mineral processing operations must be performed so that workers and the environment are protected from harm from Th and/or U (and their radioactive decay products), just as they must be protected from any other potentially harmful constituents present in the ore or introduced in processing. Examples of these might include ores with high sulfide content, which may pose a risk of acid rock drainage, or chemicals used in ore processing and metals production.The purpose of this paper is to present information on how rare earth mining and processing projects with ores containing Th and/or U can be developed, operated, and decommissioned safely according to applicable regulations intended to protect worker health & safety and the environment.It should be noted that some countries are considering developing Th as a feedstock for producing nuclear energy, which could have some effect on future development of rare earth ore deposits. To avoid confusion, that issue is not discussed in this paper."

Jan 1, 2012

By C. Tong, B. Hilscher

"Sensor based ore sorting is being rapidly adopted by the mining industry. The ability to boost mill feed grade by rejecting waste grade rocks early in the process has proven revolutionary for some operations.This paper briefly reviews the current position of ore sorting in the industry, as well as abridged results from specific operations such as Barrick, McEwen, New Gold, and two others. The paper also introduces the concept of “Profit Recovery™”, the measuring of recovery based on rock profitability rather than just metal content.IntroductionSensor based ore sorting is being rapidly adopted by the mining industry. The ability to increase mill feed grade by rejecting waste grade rocks early in the processing stage is proving to be revolutionary for some operations. These potential outcomes have been too invaluable to be overlooked by both producing operations and prospective projects, thus leading to a wide range of studies on ore sorting. In addition, the advent of ore sorting has also called for a new standard of recovery analysis. The answer to this is the creation of a new term and concept - Profit Recovery™.This paper evaluates the most recent results of ore sorting in the mining industry, and presents the results from five different mining operations. Additionally, this paper will discuss and evaluate the Profit Recovery™ of each of these operations. The goal of this paper is to address common concerns regarding ore sorting rejects and their actual impact on project economics.State Of The ArtOre Sorting is a sensor-based sorting and pre-concentration technology implemented before the processing stage that is used to reduce the amount of waste reporting to the mill feed. This technology can also be utilized to recover ore from previously uneconomic waste, as well as reduce the mill energy and reagent consumption (Tong, 2012). In greenfield projects, sensor-based sorting can further provide value by reducing processing capital costs. The decline of available high grade orebodies and decreasing head grades has further increased the attractiveness of pre-concentration, and subsequently ore sorting (Lessard et al., 2014).There are currently two notable types of sensor-based sorting: bulk and rock-by-rock. Bulk sorting consists of live, high tonnage sorting that can be installed on a scoop or on a conveyor belt with a diverter. Rock-by-rock is a selective sorting method that scans and sorts individual rocks on a conveyor belt, and rejects rocks using air jets or mechanical levers. Figure 1 shows a diagram for a typical air jet sorter."

Jan 1, 2018