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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 J. A. Meech, C. A. Harris

"The application of control theory in mineral processing is more difficult than in other industries because of the complex nature of the unit processes involved and because of problems with accurate on stream measurement of process variables. Conventional control is based on proportional, integral and derivative functions of a continuously measured error term. Computer control can enhance these actions by incorporating logical routines to switch from one relationship to another. The success of this logical approach depends on our understanding of the process dynamics and the stability of the process and model under all conditions. Typically the model does not apply at all times in mineral processing because of frequent and unmeasurable changes in the ore parameters.Recent advances in the theory of fuzzy sets have led to the application of this science to process control. Fuzzy Logic can be used to develop heuristic or rule-of-thumb controllers with the strategy based on the actual operating practice of experienced plant operators. Control action has increased flexibility through the adaptation of human reasoning. Acceptance of the control system by operating personnel is significantly higher because of their participation in its formulation. The requirement of an exact model is not essential.A heuristic controller has been designed and tested with a computer simulation model of a secondary crushing plant. The results of this study are discussed and future applications of this control technique to other mineral processes are suggested. IntroductionThe application of control theory in mineral processing is more difficult than in other industries because of the complex nature of the unit processes involved. Mineral processes typically are characterized by non-linear relationships between input and output variables. Many of these variables cannot be monitored accurately on-stream and so long time lags on the measurement loop are features of the system. The processes, themselves, often have long time-varying responses while the process loads fluctuate significantly on a short-term basis.Attempts to control these processes have led to the formulation of mathematical models to describe each unit activity. Adaptive techniques have also been tried to compensate and account for process changes and vageries. These approaches are mathematically rigorous so that their complexity and precision limit their usefulness when applied to ""vague"" processes."

Jan 1, 1987

By S. Hon, C. Searcy, R. DasGupta, B. Fleet, A. Davidse, A. Pringle

"The mining industry is facing serious long- and short-term challenges relating to uncertain commodity prices, environmental pressures, and margin compression due to rising energy costs. Energy issues, formerly treated as an operating cost, are changing as executives search for longer term solutions to deal with uncertain fossil fuel prices and greenhouse gas emissions. Consequently, mining executives are increasingly willing to consider introducing a proportion of renewable energy (RE) systems into the mine energy mix. This paper examines how RE can be successfully integrated at mine sites, as well as some of the benefits and barriers to their wider adoption.RÉSUMÉ L’industrie minière fait face à de sérieux défis, à long et à court terme, en raison de l’incertitude des prix des matières premières, des pressions environnementales et des compressions de la marge bénéficiaire dues à la hausse des coûts de l’énergie. Les questions énergétiques, auparavant considérées comme un coût d’exploitation, changent alors que les cadres cherchent des solutions à plus long terme afin de prendre des mesures pour contrer les prix incertains des combustibles fossiles et les émissions des gaz à effet de serre. C’est pourquoi les cadres miniers sont de plus en plus disposés à considérer l’introduction d’une proportion de systèmes d’énergie renouvelable dans l’équation énergétique de la mine. Le présent article traite de la manière dont les énergies renouvelables peuvent être introduites avec succès aux sites miniers ainsi que quelques-uns des avantages et des barrières à leur application à une plus grande échelle."

Jan 1, 2015

By Xiao Huang, Jean-Francois Thibault, Ali Merati, Prakash C. Patnaik

Single-crystal nickel-based superalloys are the current state-of-the-art technology for the manufacture of turbine blades. This technological improvement of the turbine blade has brought a considerable increase in its cost. Repair and overhaul of service stressed single crystal turbine components is an economic necessity for life cycle cost reduction of engines since the cost associated with replacement is significantly higher than its counterpart polycrystalline component. This paper will first review the recently reported research in developing repair technologies used for DS and SX components. These techniques repair the crack or defect while at the same time ensuring that the mechanical properties do not deteriorate and, more importantly, that the single-crystal microstructure is not jeopardized. It will then be followed by a brief overview of the research conducted and initiated by the authors with regards to the repair of single crystal alloys.

Jan 1, 2004

Advanced high temperature electrochemical systems such as fuel cells, electrolyzers and ionic transport membranes are currently being developed for a wide variety of energy conversion, storage and gas cleanup applications. These systems offer high electrical efficiency, multi fuel capability, modular construction, no/negligible emissions (SOx, NOx, VOC, particulate matters) with capability to sequester green house gas emissions (GHG). Electrochemical processes and electrode reactions will be discussed. Cell and stack component materials and fabrication processes will be presented. Bulk, surface and interface degradation processes responsible for cell and stack performance degradation will be examined.

Jan 1, 2005

By K. Morikawa, K. Asano, J. Yoshitomi

The quality requirements for ladle shrouds have become stricter year by year to the pursuit of higher productivity and improved quality in the continuous casting of steel. The ladle shrouds must be sufficiently durable under severe conditions, such as operation without preheating and during several sequential castings. The consideration is that ceramic fibres, which have been applied in shrouds for thermal insulation during casting, could pose a risk to the worker's health. We realized materials for the ladle shrouds which show high strength and low elasticity. At the same time pursuing effective insulation, a coating which contains no fibres (Foaming Coat) has been developed, replacing the conventional one containing fibres. These materials are durable under conditions of repetitive use and consequently satisfy the customer's demands. The ladle shrouds which were improved in this way have achieved an excellent durable life in hot service of three times that of conventional ones. This paper reports the recent technological developments in ladle shrouds as well as their performance under hot operating conditions.

Jan 1, 2004

By T. Navessin

Recent research activities in proton exchange membrane fuel cell (PEMFC) have significantly improved the performance per unit cost and its lifetime. These activities narrow the technology gaps, and thus, enable commercialization in some applications. One particular focus is in the development and understanding of proton conducting membrane materials. Many novel membranes are being developed which provide control and systematic understanding of complex relationships between chemical structure, morphology, physicochemical properties, and electrochemical kinetics. In this study, different classes of proton conducting membranes suitable for portable and automotive applications were evaluated in an operating PEMFC at the Institute for Fuel Cell Innovation, National Research Council. Analysis of these results may provide constructive feedbacks to the material researchers.

Jan 1, 2005

By Juan C. Sotomayor Álvarez

The Huantajalla mine is seated on Uchucchacua 's Mixing District that is the fourth producer of Silver in the world. Huantajalla Mine is a new mine that nowadays is being explored and recently it has began to operate. The project for 4-A vein exploitation in Huantajalla Mine using Longhole drillings as a new method of mixing is developed by Planning Department of Uchucchacua Mine in coordination with Geology Department of this mine, started in June 2004. This project is funded by Company of Mines Buenaventura S.A.A In July 2002, Geology Department started the exploration on the area of Huantajalla Mine, discovering the 4-A vein. The reconnaissance and definition of the vein finished June 2003, finding 79,080 Ton of mineral of Silver with a grade of 40.0 Oz Ag/ton and a thickness of 1.85 meters (6 feet ). Using the longhole method on the vein exploitation will replace the cut and fill and shrinkage methods, and it will keep a dilution of 15%.

Oct 1, 2004

By Lee Barbour

Waste-rock piles from metal mining operations are comprised of large surface deposits of unsaturated, coarse-grained soil and rock. The unsaturated condition and heterogeneous, coarsegrained nature of these deposits make them difficult to monitor or characterize. Key parameters that must be evaluated include; volume-mass relationships (e.g. water content, air content, porosity, density, degree of saturation, grain-size), transport properties (e.g. air-permeability, gas diffusion, hydraulic conductivity), geochemistry (e.g. solids, gas, and fluid phases) and soilatmospheric fluxes (water and gas). This paper describes some of the techniques that have been developed to characterize waste rock piles for uranium mines in Northern Saskatchewan. For each technique, the method of measurement is described, and preliminary field data are presented and discussed.

Nov 1, 2002

By D. Laguitton, D. Cimon

"BILMAT is one of the most powerful algorithms in existence for material balance computation in mineral processing flowsheets. It is based on a hierarchical decomposition coupled with the Lagrange multipliers method widely reported in the literature. Flowrates can be calculated optionally for pulp, solid or water. Assays are adjusted for a variety of subnetworks, such as assays of the solid as well as assays of fractions of the solid called level 4 data (l: pulp, 2:solid and water, 3:assays of solid, 4:assays of classes of solid).BILMAT4 is a new implementation of BIU1AT that operates in a new microcomputer environment and makes the method more accessible than ever. Its main features are a full-screen colour editor allowing graphic flowsheet drawing and data entry with automatic error checking. Mass balance equations are automatically generated by analysis of the graphics and corresponding data, thus relieving users from the error-prone definition of networks. Sensitivity analysis is performed to assess confidence intervals of computed flowrates and adjusted assays.BILMAT4 incorporates an option for gold leaching circuits where the element to be balanced appears in both the solid and liquid phases with negligible effect on the mass flows of solids. Recoveries are computed in all streams. This program is currently released by CANMET as part of the CAMP collection for Computer Aided Mineral Processing. A complete sample run of the program is discussed."

Jan 1, 1989

By E. Ferguson

In evaluating refractory designs for cast house applications, thermal calculations are frequently performed to determine cold face shell temperatures, temperature profiles and metal freeze plane locations within the refractory layer, and heat loss in the steady state condition. A problem arises when looking at molten metal transport crucible designs in that these structures are usually operating under non-steady state conditions throughout their production cycle. Because the molten metal temperature varies with time, and material properties such as thermal conductivity are temperature dependant, mathematical solutions are at best... complicated. This paper presents a relatively simple, iterative solution, that can be set up on a standard computer spreadsheet program, to calculate heat transfer in non-steady state conditions. These calculations can provide curves for (1) molten metal temperature vs time and (2) cumulative heat loss vs time, given variable starting conditions, to aid in the evaluation of molten metal transfer crucible refractory designs.

Jan 1, 2004

By F. Schulz

NA's primary smelter has continually increased its production output in the past decade, making it necessary to improve the lifetime of the casting moulds for copper anodes. The current throughput of more than 1,100,000 tonnes per year of copper concentrates amounts to an output of about 450,000 tonnes per year of anode copper at NA's Hamburg plant. The anodes are cast on a single casting wheel with 24 anode moulds. Besides the stable chemical analyses, the reproducible geometry of the anodes is an important precondition for the success of the subsequent electro-refining process. The anode moulds are subjected to thermally-induced alternating stress and side reactions with the melt. Typical signs of wear will be shown and discussed. Different processes to produce anode moulds will be introduced and the results in terms of their lifetime and the quality of the anodes themselves will be discussed. Finally an outlook is given on possible efficiency improvements.

Jan 1, 2007

By D. Xia

Pt-Bi intermetallic Nanoparticles was prepared by the polymer-anchor method. The electron micrographs shows that the dimensions of particles sharply distribute in the range of about 3-6 nm. The elemental ratio of Pt/Bi in the bimetallic particles is estimated by the electron probe microanalysis method. Pt-Bi intermetallic Nanoparticles shows a higher activity for the ORR than pure Pt. No significant dependence of the oxidation currents on the rotating speed of the electrode could be observed in the presence of methanol. This clearly indicates that the Pt-Bi is inactive to methanol.

Jan 1, 2005

The Rabbit Lake In-Pit Tailings Management Facility contains frozen layers of tailings due to subaerial deposition during the coldest periods of winter. Thawing is required to ensure full consolidation of the tailings and to regain disposal space presently occupied by ice. Electric resistance heating has been used to heat soil for bitumen extraction and remediation of volatile contaminants. A preliminary evaluation of the application of electric resistance heating to thaw about 0.3 cubic metres of frozen tailings was conducted using tailings frozen at about -2 oC. Visible thawing of the tailings mass was observed after 25 hours, demonstrating the feasibility of this approach.

Aug 1, 2010

By V. C. Pandolfelli, P. Bonadia, F. A. O. Valenzuela, L. R. Bittencourt

Refractories for aluminum cells, if not properly selected, can lead to increased energy consumption and even shorten the pot life. Based on recent advances in understanding the deterioration mechanism of cathode materials, several commercial bricks in the SiO2-Al2O3 system were compared to the one used by an Alcoa smelter. Both physical and chemical properties were considered in the selection of the refractories. A more reliable method of permeability measurement, which takes into account inertial and viscous effects during the fluid flow, was applied. Additionally, the traditional cup test and other characterization techniques, such as thermal conductivity, X-ray diffraction, and mercury porosimetry, indicated that a brick with a relatively low alumina/silica ratio, presenting low open porosity and low permeability, far exceeded the performance of the brick currently in use.

Jan 1, 2004

By Simon D. Handelsman, Malcolm Scoble, Marcello Veiga

"Abstract - In many mining areas, potentially profitable mineral projects can be at risk because local people do not trust their governments and mining companies on many issues, including human rights. Projects will continue to be vulnerable to potential failure, delays, and higher costs. This paper suggests that geoscientists need to be aware of the global challenges they face from issues of corporate social responsibility, sustainable development, and human rights. These are not areas in which geoscience education has traditionally focused.This paper examines the types of conflict concerning human rights that are encountered by geoscientists involved in mineral exploration and development. It provides a background to human rights issues and presents a classification of the types of issue encountered. It reports on a survey of case studies that provide examples of the breadth, complexities, and consequences of such issues. The paper then concludes by outlining the development of codes and standards to improve performance, and suggests approaches for positive, practical engagement."

Jan 1, 2003

By J. Beddoes

The various microstructural factors that influence the creep resistance of y-titanium aluminides are presented and discussed. Titanium aluminides have potential for a variety of intermediate temperature applications in both gas turbine and reciprocating engines. While it is well established that the 'fully lamellar' titanium aluminide microstructure offers superior creep properties, the particular influence of lamellar morphology, third phase precipitation, and grain boundary structure in controlling both the primary and tertiary creep behaviour is presented. The results are primarily based on tensile creep experiments undertaken using several titanium aluminide intermetallic compositions processed via powder metallurgical techniques, investment casting and Bridgman directional solidification. The results indicate that lamellar structure and precipitate formation have a major impact on primary creep, while microstructural degradation through both lamellar and precipitate coarsening influence on the onset of tertiary creep leading to fracture. The results are used to design a creep resistant microstructure produced by directional solidification and the effectiveness of this designed microstructure is demonstrated through 10,000 hour creep tests.

Jan 1, 2004

By R. D. MacEchern, M. C. Rockwell

"This paper describes the research and tests carried out to recover the readily available barite from the tailings produced by the Nystone Chemical Ltd. operation at Debert, N.S. The tailings comprised 70-80% of the original feed and contained about 20-25% Baso4 .The objective of the research, undertaken during 1982, was to produce a barite concentrate which would meet the American Petroleum Institute (API) barite requirements for use in drilling mud. Samples from the tailings pond were examined and analysed to determine the tailings characteristics.Preliminary test work was performed on the tailings samples using a Haultain Superpanner, Wilfley tables and Humphrey's spirals. The grade of the barite concentrate retrieved did not satisfy the API barite requirements.The fineness of the tailings and the fact that approximately 80% of the barite was contained in the -200 mesh (0.074 mm) size fractions, indicated that flotation of barite from the tailings might be successful."

Jan 1, 1984

By Sheila E. Daniel

"Since 1989, the Mine Environmental Neutral Drainage Program (MEND) has sponsored research into ways of reducing the environmental impact and financial liabilities associated with Acid Mine Drainage from tailings and waste rock. Toward this overall objective, Kilborn was contracted to review the use and applicability of passive treatment systems for acid mine drainage.Experimentation using passive systems to treat acid mine drainage has been ongoing since the early 1980's in North America. Passive treatments are generally considered an attractive alternative to active lime treatment, since they require minimal human involvement, no power, and only seasonal or periodic care and maintenance after establishment. Most attractive is that initial capital cost to implement a passive treatement system is generally low to moderate. Ongoing operating costs are similarly low when compared to active treatment systems.Passive treatment systems currently used, or under investigation to treat acid mine drainage include: anoxic limestone drains, aerobic wetlands, reed bed wetlands, compost wetlands, microbial systems and bioabsorption systems. These wastewater treatment systems utilize the chemical, biological and physical removal processes that occur naturally in the environment to improve wastewater quality, including: oxidation, reduction, coagulation, adsorption, absorption and precipitation; microbial activity; and, gravity aeration and dilution. The rates at which these processes occur determines the loading which can be treated and the effectiveness of the system.The results of our literature review will be summarized, and insight provided into the applicability of passive systems to treat acid mine drainage from Canadian Mines."

Jan 1, 1995

By K. W. Fritzsche

The prosperity of any nation depends, to a large extent, on its natural resources such as oil, coal, 'metal, timber, waterpower, and fertile soil. Each one of these resources forms the basis of a huge industry. The mining and smelting industry ranks among the first since it paves the way for a number of other industries. The mines and smelters provide a market for electric power, coal, timber, and agricultural products: other industries in turn provide a market for metals and non-metals. The real pioneering, however, is done by the prospector who goes into the wilderness to search for the ores from which the metals are to be extracted for the use of men. Prospecting is an interesting and fascinating occupation. There are many difficulties and hardships in the way but the lure of gold and the vision of finding an outcrop that may develop into a large bank account, within a reasonably short time, will urge the prospector forward. Thus, on the outskirts of this northern hemisphere hundreds of prospectors are searching and toiling and of whom nothing is known or heard until they reach civilization and announce a new discovery. Then a mad rush takes place and everybody who can afford to go will take a gamblers chance and plant stakes in the neighbourhood of the new discovery, or wherever an outcrop of mineralized rock can be found, with the hope of winning a fortune.

Jan 1, 1925