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By S. B. Mishra

Ni-20Cr metallic coating was deposited on a Ni-based Superalloy (3Fe-19.5Cr¬0.3Ti-Balance Ni) by a shrouded plasma spray process; NiCrA1Y was used as a bond coat. Erosion studies were conducted on uncoated and plasma-spray coated superalloy specimens using an air-jet erosion test rig at a velocity of 40 m/s and impingement angles of 30° and 90°. The coating has been characterized for porosity, microhardness and microstructure and X-Ray Diffraction (XRD). An electron probe micro analyzer (EPMA) was used to obtain X-ray elemental mappings of the coating along the cross-section. Scanning electron microscope (SEM) with EDAX attachment was used to analyze the eroded surfaces.

Jan 1, 2005

By J. A. Finch

Solvent-coated air bubbles in the Air-Assisted Solvent Extraction (AASX) process achieve the dual role of high solvent specific surface area and ease of phase separation. The thickness of the solvent film is of fundamental interest but difficult to measure directly in the process itself. As an approach interferometry (in the UV-vis region) was used to measure the time dependent thickness of a film formed by blowing an air bubble in kerosene-based solvents. The film was stabilized by the presence of 1.5 ppm silicone oil, as employed in AASX. The film appears to comprise two layers; an outer "free" layer of almost constant thickness and an inner "bound" layer which decreased in thickness with time. The bound layer is considered relevant to AASX. For a 20 mm diameter bubble blown in LIX/kerosene solvent the initial thickness was ~ 3 um which decreased over 10 minutes to a final rupture thickness of 500 nm. The bound layer thickness and time to rupture decreased with decreasing bubble size. Correspondence to prior indirect estimates of solvent layer thickness is examined.

Jan 1, 2006

By Didier Fohlen

Three Policy Shifts to enhance IFC?s Accountability ? Comprehensive and dynamic treatment of social, health, safety and environmental risks ?Covers a range of risks encountered by clients in emerging markets ?Framework to anticipate risks and to address them as they arise ?Includes community development, biodiversity, human rights ... ? Effective principles to guide an outcomes-based approach ?By clients and IFC ?Focus on broad community support and value-added sustainable development initiatives Enhanced governance, transparency and disclosure

May 1, 2006

By K. Adham

Iron chloride pyrohydrolysis (ICP) is used as an efficient way to fix iron as an oxide, for sale as a by-product or for safe disposal. Iron chloride is reacted with water at elevated temperatures to yield iron oxide and hydrogen chloride. Both the steel industry and synthetic rutile producers make extensive use of ICP. Two technologies are available for ICP: fluidized bed (FB) and spray roaster (SR). Both technologies are energy intensive. Here, fluid beds and spray roasters are compared with respect to their fuel and electrical energy consumptions. Roaster size and oxide product characteristics are also considered. Process models are prepared, using the METSIM® software, and specific energy consumptions are compared. The results will help the industry decide which technology best suits its goals and at what energy cost.

Jan 1, 2006

By N. Djilali

Many of the transport phenomena encountered in proton exchange membrane fuel cells occur intrinsically at the microscale level. Physically representative models that fully account for the salient physico-chemical and transport processes in PEM fuel cells are necessary to achieve truly predictive models that can be used with confidence to: (i) gain a better understanding of in-situ processes and couplings, (ii) explore new concepts, and (iii) support design and optimization. The development of more general, rationally based macroscale models requires use of knowledge on the microscale level to provide guidance, and to determine the required parameters and coefficients (model "constants"). In this paper we present a new membrane transport model, the binary friction membrane model (BFM2), recently developed to account for coupled protonic and water transport in polymer membranes. This general model is based on rational and physical consideration, removes several of the limitations of the empirical models used to date, and is formulated for all purfluoro-sulfonic acid membranes. The use of the BFM2 in a fuel cell model is illustrated highlighting significant performance predictions compared to existing empirical model. The second part of the paper addresses the fundamentals of two-phase transport in hydrophobic gad diffusion media. Computational and experimental visualizations resolving the microscale dynamics of water transport between the fibres of a GDL are presented, revealing transport mechanisms that are, contrary to assumptions used to date, dominated by fingering and channeling.

Jan 1, 2005

? Introduction ? Partenariat MRNF - MAE ? Goldex ? Manitou : - Ré-aménagement du bassin versant - Accès aux zones problématiques - Filtration du ruisseau pour les travaux - Nettoyage près de la rivière - Régulation du débit et bassin - Digues et bassins - Déposition résidus Goldex ? Chemins d?accès Goldex-Manitou ? Pipelines: Goldex ? Retour Goldex ? Manitou ? Station de pompage ? Résumé

Feb 1, 2008

By William H. Pomroy, Kenneth E. Hjelmstad

An underground mine fire can seriously threaten the lives of all personnel in the mine. This fact makes fire emergency planning a high priority in the mining industry. A fire emergency plan includes a means of warning miners of the existence of a fire, and the need to evacuate or retreat to a place of refuge. The warning alarm must be fast and must reach all miners, regardless of their location or work activity. Means of fire warning are varied, and include such methods as stench, flashing lights, telephones, and word-of-mouth (messengers). Unfortunately, none of these methods are entirely satisfactory. Stench can be slow and seldom achieves total mine coverage, especially in high-back room-and-pillar mines with low ventilation velocity. Telephones are effective only where personnel are close enough to hear the phone ring. A novel fire warning alarm system has been developed by the U.S. Bureau of Mines which enables instantaneous warning of all underground personnel. The warning alarm is sent by an electromagnetic signal which penetrates through mine rock from a transmitter to small person-wearable receivers. Each miner's cap lamp battery could be equipped with a small receiver and when a fire or other emergency occurs the miner could be alerted to the danger by a blinking of the cap lamp. Testing of prototype equipment has demonstrated that the transmitted signal is capable of penetrating through over a mile of mine rock and activating the receiver. This paper describes the theoretical basis for through-the-rock ultra-low frequency electromagnetic transmission, design of the prototype transmitter and receiver, test results, and status of commercial development of systems utilizing this technology.

Jan 1, 1994

By Simon Houlding

"Part 1 (CIM Bulletin, August 1991) of this article identified the limitations of the traditional modelling methods and demonstrated the approximations and errors introduced by their application to complex mining situations. The objective of Part 2 is to describe the evolution of new, proven technology which eliminates these deficiencies and provides precise and practical alternatives. These promote the use of realistic geological and mining shapes and eliminate altogether the rectangular approximations of traditional methods. Limitations of the Traditional MethodsThe limitations of the traditional modelling method s (viz. simple block modelling, gridded modelling and their more recent variations) were discussed in detail in Part I . These methods are all based on the use of rectangular discretization to represent the boundaries and volumes of ore deposits and mining excavations. As a result they are unsuited to the representation of nonrectangular geological complexities such as folding, faulting and irregular surfaces . They are equally unsuited to the representation of realistic excavation limits, particularly in the case of underground mining.Recently these methods, with limited variations in technique, have been applied to increasingly more complex geological and mining situations. The resulting potentials for error and conflict within the modelling pro cess were demon strated in Part I . The effects can be summarized as follows:• volume and boundary approximations introduced by therepresentation of irregular three-dimensional boundaries andvolumes by rectangular modelling elements ; • geostatistical errors and conflicts caused by neglect of the relationships between grade estimates and the geometric/ spatial aspects of irregular volumes and associated observations (samples), including an inability to produce precise estimates with meaningful confidence limits;• a compounding of these effects by using rectangular element sizes other than the geostatistical optimum, and by using differentelement sizes within a model; and• general inefficiencies introduced throughout the modelling pro cess by the requirement to represent geology, grade distribution and excavation limits with a singular modelling method and model."

Jan 1, 1991

By W. P. Clement, M. C. Bell

"PT International Nickel Indonesia, a subsidiary of Inco Limited, mines and processes nickel laterite ores for the supply of nickel matte, primarily to the Japanese market. It has large ore reserves and a substantial portion of its energy requirement is supplied from its own hydro-electric plant. Since the early 1980s, the company has increased its production level and has dramatically reduced its unit costs. Projects are in progress to further decrease costs and recently a major expansion - 31% increase in nominal capacity - has been undertaken, consistent with marketing opportunity in Japan. The expansion project, which has a low capital cost per unit of production, is outlined in this paper.IntroductionPT Inco is a fully integrated mining and smelting facility located in Indonesia on the island of Sulawesi, and is based on a very large, world class nickel laterite orebody located 60 km inland from the Gulf of Bone. Construction of a single furnace line plant started in 1973. Complete supporting infrastructure of townsite, hospital, schools, shopping centres, road systems, and an airport, all had to be built. Prior to completing the first phase, the decision to expand the plant to a three kiln-furnace line was made. A major factor in the decision was the ability to develop the hydroelectric potential of the nearby Larona River. This involved construction of a 30 m high dam, and a 7 km surface canal to the generating station. The penstocks drop 150m to three 55 Mw turbines. The power generated is sufficient to supply the entire electrical load for the complete smelting complex and town site. The unique capability to supply the high smelting energy requirements for a lateritic nickel ore by fully captive hydro power, has, over the past decade insulated PT Inco from the large upward swings in oil prices suffered by other lateritic nickel producers.Wet ore is first partially dried to 20% moisture in two co-currently fired rotary driers, screened on an internal trommel, and delivered to two dry ore storage buildings. The partially dried ore is calcined at 750°C and partially reduced in three large 100 m by 5.5 m kilns. Reduction is accomplished by lancing bunker C oil onto the ore bed at the discharge end of the kiln. The kilns are equipped with five air pipes with onboard blowers to gradually bum the combustible gases generated by the lance oil. The kilns were also originally equipped with two side burners to supply additional heat close to the feed end of the kiln. Calcined ore is transferred by 20 ton refractory lined containers to the furnace feed bins at the top of the smelter. Smelting is carried out in three 18 m diameter furnaces powered by 45 Mw transformers. Slag is skimmed at 1550°C through water cooled breast plates and removed to the slag dump by Haulmaster Carriers. Matte of 25% Ni, 1O% S, 65% Fe is tapped at 1350°C into the converter aisle. The iron is slagged in converters to produce a nickel sulphide matte at 80% Ni. Three rotary Kaldo converters were initially installed. The product matte is granulated, dried, and shipped in returnable rubber bags to Japan. Most of the matte is fluid-bed roasted to nickel oxide and then directly reduced in a second reducing fluid bed reactor at our facilities in Japan.The smelting complex was designed to smelt two million tonnes of dry ore per year, equivalent to 34 000 tonne nickel production at an ore grade of 2% Ni. The cost of the entire project including working capital was $900 million."

Jan 1, 1990

By G. Mucsi, J. Faitli, K. Bohács

"The authors developed an online tube rheometer to supplement a Netzsch MiniCer (Netzsch GmbH, Germany) stirred media mill in order to monitor online the rheological characteristics of the suspension and therefore the result of grinding during the process. Previously it was demonstrated that the above measuring system was working appropriately based on the preliminary tests. The product related stress model was applied for the evaluation of the grinding results. It was found that the suspension concentration and the change of the material properties during grinding, consequently the rheology strongly affects the grinding result, i.e. specific surface area, median particle size as well as specific grinding energy. The tested model limestone – water suspensions behaved Newtonian initially, then after a given grinding time their properties had changed and they become Bingham plastic. INTRODUCTIONStirred media milling now is a common practice to produce fine and ultrafine granular materials for different purposes. With an increasing demand of ultrafine powders for industries (Kwade, 1999), wet and dry ultrafine grinding has been increasingly used in various fields, such as minerals (Mucsi, Rácz, & Mádai, 2013)(Rácz, 2014), ceramic materials (Becker & Schwedes, 1999), pigments (Ohenoja, Illikainen, & Niinimäki, 2013), chemical products (Baláž et al., 2013), microorganisms (Kwade & Schwedes, 2002) and pharmaceutics (Afolabi, Akinlabi, & Bilgili, 2014). It is well known that suspension rheology affects the wet comminution of materials (He, Wang, & Forssberg, 2006a). The rheological behaviour of the suspension containing the ground particles might indicate the level of interparticle interaction or aggregation and therefore it is an important variable factor of the process control (Muster & Prestidge, 1995). The influence of the rheological behaviour of mineral suspensions on their grindability has attracted more and more interests and attention, especially on ultrafine grinding performance (He, Wang, & Forssberg, 2006b) (Bernhardt et al., 1999). However, there are still many issues concerning the machine and the process for the different applications. When grinding is effective and the particle size range decreases significantly, the circulating suspension is becoming typically non-Newtonian. The changed rheological behaviour and the increasing rheological material parameters can negatively affect the grinding efficiency; therefore it is an important issue. Ultrafine stirred media milling as well as solid-liquid two phase flow have been studied for a long time at the Institute of Raw Materials Preparation and Environmental Processing of the University of Miskolc. Regarding ultrafine grinding the research is focusing on the description of materials’ grindability (energetic aspects) both in wet and dry circumstances (Mucsi et al., 2013; Rácz, 2014). Concerning rheology, the three measuring pipes tube rheometer was developed decades ago (Faitli & Gombköto, 2015). So far many different solid materials from all over the world had been tested in this rheometer (Faitli & Gombköto, 2015). Main aim of these tests was to gain basic data for large scale hydraulic transport applications. Among the many stirred media mills there is a Netzsch MiniCer mill at the Institute. It was reasonable to combine the two fields together, and the goal of the research presented in this paper is to develop an online tube rheometer for the Netzsch mill and to carry out grinding and rheological testing simultaneously."

Jan 1, 2016

By G. Danha, S. Wabula, D. Glasser, D. Hildebrandt, N. Hlabangana

"Impact tests on single particles or a bed of particles are used to determine the fracture characteristics of particles. Many different techniques have been adopted in comminution in order to find ways of optimizing energy consumption in the size reduction process. In this paper, we apply one such method called the Attainable Region (AR) analysis technique to optimize the impact energy on a bed of silica particles. The attainable region is a fundamental approach that is equipment-independent and can be used to analyze breakage processes. The AR is defined as a set of all possible outcomes, for the system under consideration that can be achieved using fundamental processes operating within the system.INTRODUCTIONThe energy crisis in Southern African has reached such critical levels, that most cities in countries like Zambia, Zimbabwe, Lesotho, Swaziland and even South Africa are experiencing load shedding challenges lasting sometimes up to 18 hrs a day. Southern Africa is well known for its riches in mineral resources, and the economies of most states in this region are driven by the mining & mineral processing sector. With the emergence of small scale miners due to government empowerment policies, national energy providers have had to resort to power cuts mainly to domestic users in a bid to cope up with the huge industrial electricity demands.It has been estimated that about 4% of the total energy used in the world is consumed by the mineral processing sector (Fuerstenau & Lutch, 1999). Tomanec and Milovanovic (1994) estimated that milling alone accounts for more than 50% of the total power used in mineral processing, but this can rise to as high as 70% for hard or finely dispersed and inter-grown ores. Today, the greatest challenge in mineral processing is how to optimize energy input to the size reduction process (Dey & Das, 2013; Nomura & Tanaka, 2011), where it has been observed that only a small percentage (1.5%) of the total energy input really does the breaking (Khumalo et al., 2008) while the rest is consumed by the equipment concerned and lost to contacts that do not result in breakage. The immediate benefits of focusing research on the optimization of energy in size reduction operations in the mineral processing sector lies in potential savings on industrial electricity usage that may then be directed towards domestic users."

Jan 1, 2016

By Irving Wigden

The world is fast becoming information based. Mine companies migrate business infrastructures to be handled electronically. Suppliers move onto the worldwide web. In this ?e-world? successful suppliers will recognize they no longer trade in just equipment, but in knowledge. Companies can no longer just provide products and services, but instead must find ways to harness their knowledge to provide new value for customers. Mine customers will be attracted to suppliers that can help them streamline the process and use Information Technology to optimize operations, increase profit, reduce cost and enhance shareholder value. With the continued move to industry standard communications and software platforms, technology that formerly stood alone can now be integrated with other technologies. This creates more powerful systems that mine operators can use quickly, easily and cost effectively. These unified architectures improve productivity, provide higher asset optimization and allow more informed decision-making. As a leading supplier of process automation solutions for the industry, ABB provides a dynamic range of such control systems. These systems are designed for instrumentation controls, variable speed drives, electrical distribution, electrical equipment and related services for Mine Automation. Enhanced by ABB´s new family of integrated software solutions ? collectively known as Industrial IT ? ABB´s control and Scada systems place you in the best position to optimize your plant, process and enterprise operations. The paper discuss system integration and installation of High-Tec system in an underground mine. ABB has the ambition to be a System Integrator and co-operate with partners in different areas of technology. To day it is a problem to find one Supplier that can be responsible for the complete Automation System. The design of the system is also much depending of the design of the mine and also which caving procedure that is used in the current mine. Much of the work must be done in a feasibility study and during the design phase. If there is careful planning and consideration during these phases is vital in order to avoid costly changes during the commissioning phase The paper will also include a presentation of the benefit of using Automation in an Underground Mine, and how important the integration of the Human Being is to the Automation System. The most profit gained in mining industries are received when the mines can reduce internal and external disturbances in the production flow and speed. Must of the experience and discussed in this paper is from advanced technology, that has been developed in Scandinavian and adopted of LKAB in Kiruna. The author of this paper has been responsible för the Automation projects in the Kiruna Mine during 1994 - 1999. These projects include: Broadband communication of data, audio, compressed video in one data stream. Control System for Haulage -1045m Automation of Load Haulage and Dumping machines (LHD) Control of Production Drilling Riggs from a Central Control Room.

May 1, 2002

By J. Oliveira, A. R. Barnes, R. Pandher

Sub-stoichiometric roasting of arsenic-bearing copper ores is a well established practice. However, ores containing calcium commonly prove challenging where very low arsenic levels are desired, but the reasons for this phenomenon have largely been speculative. In the course of treating arsenicbearing copper ores by partial roasting in fluid bed reactors, XPS encountered one of these Ca-bearing ores which proved a challenge to roast to acceptably low levels of arsenic. Mineralogical examination of the calcines using a combination of XRD (X-ray diffraction), QEMSCAN (Quantitative Evaluation of Materials by Scanning Electron Microscope) and EPMA (Electron Probe Micro-Analysis) helped to identify the arsenic bearing species and assisted in developing a workable theory on the sequence of reactions occurring during the roast. With the assistance of thermo-chemical modelling, this allowed adjustment of the roasting conditions to minimise the amount of arsenic retention in the calcine in spite of the presence of calcium in the ore and advance the roasting program to a commercially acceptable solution.

Jan 1, 2014

Concentrator Improvements -1990-1995Back to Basics ?pilot plant versus plant opportunities identified ?understand process fundamentals & baseline -1996-2000Point ?C?Projects ?strategy to improve global competitiveness ?structure implemented to generate & drive ideas ?capital investment for life of mine asset renewal - 2001-200?Six Sigma Methodologies ?emphasis on data, measurements & analyses ?dedicated, highly trained personnel on projects 1990-1995 Improvement Phase??Philosophy??back to basics?approach?understand what each piece equipment needed to do?understand reagents, control variables?confirm operating strategies ??probe, stabilize, institutionalize??test theories, confirm with lab and plant trials?process stability (equipment reliability, controls)?enhanced operator guidelines, operator training?focus on continuous improvement?optimize existing equipment capability?stop looking for ?magic?solutions 1990-1995 Improvement Phase??Technical?finer grind, same equipment?optimize media size/shape to grinding application?balanced available ball mill power to applications?lowered cyclone feed densities where possible?improved selectivity, same equipment?balanced available cells to applications?streamlined process (eliminate process steps)?added cleaning stages where required?understanding pulp/mineral surface chemistry?lowered flotation pulp densities 1990-1995 Improvement Phase??Effort?numerous studies to understand process?liberation and mineralogical characterization?pulp and mineral surface chemistry?flotation kinetics and entrainment?extensive internal and external manpower?Brunswick, Noranda Technology Centre?CanMet, AMTEL, MinnovEx, Lakefield Research, McGill University?small capital expenditure

May 1, 2002

By Irving Wigden

The world is fast becoming information based. Mine companies migrate business infrastructures to be handled electronically. Suppliers move onto the worldwide web. In this ?e-world? successful suppliers will recognize they no longer trade in just equipment, but in knowledge. Companies can no longer just provide products and services, but instead must find ways to harness their knowledge to provide new value for customers. Mine customers will be attracted to suppliers that can help them streamline the process and use Information Technology to optimize operations, increase profit, reduce cost and enhance shareholder value. With the continued move to industry standard communications and software platforms, technology that formerly stood alone can now be integrated with other technologies. This creates more powerful systems that mine operators can use quickly, easily and cost effectively. These unified architectures improve productivity, provide higher asset optimization and allow more informed decision-making. As a leading supplier of process automation solutions for the industry, ABB provides a dynamic range of such control systems. These systems are designed for instrumentation controls, variable speed drives, electrical distribution, electrical equipment and related services for Mine Automation. Enhanced by ABB´s new family of integrated software solutions ? collectively known as Industrial IT ? ABB´s control and Scada systems place you in the best position to optimize your plant, process and enterprise operations. The paper discuss system integration and installation of High-Tec system in an underground mine. ABB has the ambition to be a System Integrator and co-operate with partners in different areas of technology. To day it is a problem to find one Supplier that can be responsible for the complete Automation System. The design of the system is also much depending of the design of the mine and also which caving procedure that is used in the current mine. Much of the work must be done in a feasibility study and during the design phase. If there is careful planning and consideration during these phases is vital in order to avoid costly changes during the commissioning phase. The paper will also include a presentation of the benefit of using Automation in an Underground Mine, and how important the integration of the Human Being is to the Automation System. The most profit gained in mining industries are received when the mines can reduce internal and external disturbances in the production flow and speed. Must of the experience and discussed in this paper is from advanced technology, that has been developed in Scandinavian and adopted of LKAB in Kiruna. The author of this paper has been responsible för the Automation projects in the Kiruna Mine during 1994 - 1999. These projects include: Broadband communication of data, audio, compressed video in one data stream. Control System for Haulage -1045m Automation of Load Haulage and Dumping machines (LHD) Control of Production Drilling Riggs from a Central Control Room.

May 1, 2002

By J. Dufour

Although the recovery of nitric and hydrofluoric acids from stainless steel pickle liquors has been solved by several methods, such as solvent extraction, acid retardation, evaporation or pyrohydrolysis, metals (mainly iron, chromium and nickel) are usually obtained as a waste or by-product that has to be disposed. Alternatively, the treatment requires a high liquor flow to be economical, as is the case for pyrohydrolysis. A new process has been developed for metals recovery, that produces metal oxides with a low fluoride content. This new technique is based on a selective precipitation mechanism, which produces nickel hydroxide with a purity of 90%, separate from a mixture of iron and chromium oxides and hydroxides suitable for recycling. The reaction mechanism is based on the precipitation of fluoride compounds of iron and chromium, K2FeF5 and CrF3. For this purpose, free fluoride must be added as potassium fluoride. Also, solid fluoride compounds are hydrolysed, releasing free fluoride. A part of the fluoride is recycled to the selective precipitation operation and the remainder is fed to the acid recovery stage. Nickel does not react in this operation; it remains in solution giving a high separation yield.

Jan 1, 2006

By T. Gonzales, M. Maleki, M. Caçador, B. Climenhaga, H. Ghorbani

The campaign life of furnaces in the copper making industry is greatly affected by damage caused by normal operation cycling and abnormal conditions. Proper monitoring and assessment of the existing conditions and safe remaining life of the vessels and their refractory lining is key to prevent an unplanned early replacement. This paper presents an industry-proven refractory management program as well as a typical fitness-for-service assessment of a rotary vessel shell in order to extend the campaign life of copper making furnaces and enhance safety. The furnace refractory management system involves a comprehensive audit and monitoring program which has been successfully applied to several copper flash smelting furnaces over the past 15 years. The fitness for service assessment provides a methodology to estimate the remaining life of the steel components by evaluating the existing damage and future damage rate based on the historical survey data. The above practices can provide the operator with cost savings by extending the vessel campaign life in lieu of implementing more rigorous refractory lining and shell audits. INTRODUCTION Primary copper smelting is generally divided into two categories of flash smelting and open bath smelting. There are many different types of vessels that can be used to convert the copper concentrate to blister copper including, flash, Mitsubishi process, TSL (ISA/Ausmelt), SKS Bottom Blowing, Anode and Teniente/Noranda furnaces, reactors, and Peirce Smith converters. Each vessel has its own complex and intense environment which requires careful refractory and steel design to withstand the severe thermomechanical and thermochemical attacks within its campaign life. The campaign life of furnaces is greatly affected by damage caused by normal operation cycling and abnormal conditions. Proper assessment of the existing conditions and safe remaining life of the vessels and/or refractory lining is key to prevent an unplanned early replacement. This paper presents an industry-proven refractory management program as well as a fitness-for- service assessment methodology to estimate the remaining campaign life of copper making furnaces resulting in cost savings and enhanced safety of the operating vessels.

Jan 1, 2019

By Zia Pirzada

"Time is of the essence" and "Time is money" These are powerful and true statements during a project life cycle and have far-reaching implications on the success and failure of the project Time and progress management is crucial to the project success. Project delays may increase the cost to an unacceptable level and may render the project as economically unfeasible. On the other hand, if the project is completed on time or earlier than as planned, it may generate economic benefits greater than what had been envisioned To take advantage of the financial opportunities and to improve the cash flow as well as Return On Investment (POI), project schedule can be accelerated to complete the project earlier than planned Project schedule acceleration can be achieved by using analytical tools, such as "Schedule Optimization", "Schedule Reduction", "Schedule Compression" or a combination of any of these concepts along with the "Planning for start up". Schedule optimization does not entail any extra cost, however, other acceleration methods, such as Schedule Reduction and Schedule Compression, may require extra expenditures from the owner. Based on the forecasted early start of the revenue stream, the extra expenditure could become a worthwhile venture with a very high rate of return To accelerate the schedule, all aspects of the project should be reviewed with acceleration costs calculated. All risks and opportunities should be evaluated and taken into consideration to determine if the acceleration is feasible and advisable and will provide definite financial advantages Sometimes schedule acceleration may be desired to prevent the company from paying liquidated damages. This is especially true when the project is not expected to complete on the contractual completion date and when the cost of acceleration is less than the liquidated damages that may accrue against the company.

Oct 1, 2010

By S. Esmaeili

The yield strength model developed by Esmaeili, Lloyd and Poole [1] has been adapted to model isothermal aging in Cu-containing AA6xxx alloys, with (a) a moderate and (b) a very low Cu content in the solution-treated, as-quenched, condition, Isothermal calorimetry has been used to analyze the kinetics of precipitation in these alloys, While the kinetic parameters for the low Cu alloy has been derived from the present experiments, the previously determined kinetic parameters for the high Cu alloy AA6111 has been used to model the precipitation kinetics in the moderate Cu alloy. The age hardening responses of both alloys have been well predicted by the model.

Jan 1, 2005

In terms of throughput, product size and power draw, grindcurves provide a measure of the response of the mill performance to changes in mill operating parameters ? usually mill filling. Since presenting the principle in 2006, grindcurves have been applied to a wide variety of AG and SAG mills. Mill response has been carefully measured for variations in: mill fillings from 15% to 40%; throughput by a factor of two; power by 50%; feed blends; liner profile; and mill speed from 65% to 80%. The outcomes of this extensive program of work are presented as the measured grindcurves. How they have enhanced our understanding of mill operation and how they may be applied to practical daily mill control is discussed. It is proposed that this technique provides a viable and valuable mill control tool that may find extensive application in the industry.

Jan 1, 2012