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By M. Reda

Erosion corrosion is acceleration in the rate of corrosion attack in metal due to the relative motion of a corrosive fluid and a metal surface [1]. The increased turbulence caused by pitting on the internal surfaces of a tube can result in rapidly increasing erosion rates and eventually a leak [2]. Engineers and scientists in different disciplines have worked for many years on methods of complete protection from flow induced corrosion or partially reducing corrosion of this type, and they have proposed or applied different countermeasures [2]. The accident at the Surry-2 nuclear power plant (USA) and other similar incidents have once again disturbed the scientific-technical community. This has forced the plant operating personnel and the management to undertake wide-ranging measures in order to discover on time, assess, and monitor such cases. In these extreme cases, protective coating and even metallic bulk material coating (the substrate itself) may suffer considerably from mechanically induced damage [2]. At high velocities, the "leaching out" dissolution reaction of particular, for example, steel elements at the solid-liquid interface become the rate determining step. One practical example for the difference between erosion corrosion and flow induced corrosion is the famous steam eruption from a Japanese [3, 4] nuclear power plant cooling system at the pressurized water reactor (PWR), turbine and in the condenser-steam generator connecting pipe. The rupture occurred in the carbon steel pipe connecting the condenser and steam generator. The damage occurred in the easily eroded/corroded carbon steel at a vulnerable location downstream of an orifice plate, In general, when there is significant reduction in pipe thickness through erosion/corrosion, distinctive patterns are visible, but those patterns were not observed in this case, Thus one can speculate that another phenomenon is possibly controlling, Fluid flow within pipes reduces the pipe thickness leading to an eventual rupture, The thickness reduction mechanism is erosion/corrosion, One example is "cavitations corrosion", Erosion and corrosion occur at the same time, and it is difficult to determine which one is dominant, Therefore, the term, "erosion/corrosion," is used [5]. In the atomic energy field, the terms "Flow Accelerated Corrosion" and "Flow Induced Corrosion" are also used. It is the purpose here to show that during flow induced corrosion a different mechanism may possibly be operating and in some cases it can be different from the well known erosion corrosion. Another example is fretting failures in early Canadian nuclear steam generators which was thought to be due to excessive vibration caused by high.

Jan 1, 2010

?Four-wheel, skid-steer, rover developed for CSA ?U-chassis for payload accommodation ?Passive geometric suspension ?Max speed 13km/hr ?Remote workstation ?275kg payload capacity ?On-board processor, IMU, motor encoders ?5.2kW-h battery capacity

May 1, 2013

By Earl Gebhardt

The planning and design of mining panels in the Potash Corporation of Saskatchewan Inc., Lanigan Division mine Block B involved a number of investigative techniques. The techniques utilized to gain insight into the viability of mining included 2-D and 3-D seismic surveys, longhole drilling, exploration wells, photolineament, magnetic and gravity surveys, and actual room excavation.

Feb 1, 1993

By F. Habashi

"A short account will be presented on the extraction of rare earths from monazite sand, bastnasite ore, and phosphate rock of igneous origin. This includes mineral beneficiation, leaching methods, fractional crystallization [of historical interest], ion exchange, solvent extraction, precipitation from solution, and reduction to metals. INTRODUCTIONOriginally, the term rare earths was only used for the oxides, R2O3, which are similar to one other in their chemical and physical properties and are therefore difficult to separate. Within the rare earth group, the elements scandium, yttrium, and lanthanum differ in their atomic structure from the elements cerium to lutetium (the lanthanides, Ln). Scandium occupies a special position with respect to this classification and its other properties, and therefore does not belong to either of these groups. The rare earth elements always occur in nature in association with each other. The isolation of groups of rare earth elements or of individual elements requires costly separation and fractionation processes owing to the great similarity of the chemical and physical properties of their compounds, which explains why the history of their discovery has extended over such a long period.The word “rare”, when used to describe this group of elements, originates from the fact it was thought that these elements could only be isolated from very rare minerals. Considering their abundance in the Earth’s crust, the term rare is now inappropriate. These elements are lithophilic and are therefore concentrated in oxidic compounds such as carbonates, silicates, titano-tantalo-niobates, and phosphates.The abundance of the rare earth elements taken together is quite considerable. Cerium, the most common rare earth, is more abundant than cobalt. Yttrium is more abundant than lead, whereas Lu and Tm are as abundant as Sb, Hg, Bi, and Ag. For all practical purposes promethium does not occur in nature. It forms only in nuclear reactors."

Jan 1, 2012

By M. B. Kime

"Discrete-element method (DEM) modelling is a powerful tool for studying particulate systems within the mineral processing industry. DEM simulations were conducted to investigate the power draw, load behaviour, and impact energy profile of an experimental ball mill under different milling conditions. The variables considered were mill rotational speed (percent critical speed), ball size, and lifter face angle. The simulation results indicated that the grinding efficiency would be enhanced by using 80% critical speed, 30 mm ball diameter, and 45° lifter face angle. These findings can be useful in guiding actual ball milling tests involving an ore sample.RÉSUMÉ La modélisation par méthode des éléments distincts (MED) est un outil puissant qui permet d’étudier les systèmes particulaires au sein de l’industrie de traitement des minerais. Des simulations par MED ont été menées de façon à étudier le profil de la consommation énergétique, du comportement de la charge et de l’énergie de rupture d’un broyeur à boulets expérimental dans diverses conditions de broyage. Parmi les variables prises en compte figuraient la vitesse de rotation du broyeur (vitesse critique en pourcentage), la taille des boulets et l’angle de coupe de la cornière élévatrice. D’après les résultats de la simulation, on pourrait améliorer l’efficacité de broyage en utilisant une vitesse critique de 80 %, un diamètre de boulet de 30 mm et un angle de coupe de 45 ° de la cornière élévatrice. Ces résultats peuvent se révéler utiles pour les essais concrets de broyage à boulets impliquant un échantillon de minerai.INTRODUCTIONComminution is a very energy intensive process. It consumes approximately 5% of the electricity produced worldwide and more than 50% of the total energy used in mineral processing plants (Pokrajcic, 2010). Among all the comminution stages, ball milling is one of the most energy intensive processes. In ball mills, rotational movement provides the rise of the load and the media that are projected and impact on the mill shell at lower angular displacement, resulting in particle breakage. Ball mills are able to reduce particle size over a relatively wide range of particle sizes. This explains their wide applicability in research laboratories and the mineral processing industry."

Jan 1, 2017

By Pierre Antoine Dhaiti, Gilbert Sergerie, Michel Dagbert, Jean-Maurice Brodeur

"Quality of iron ore is generally determined by several factors which can be correlated or independent. Among these f actors, we generally find per cent iron, silica, magnetite or hardness. Forecasting the short- and long-term fluctuations of these f actors in the future pit is an important feature of mine planning in these deposits. Computer simulation provides a realistic answer to these questions. It allows to generate values for the most important quality features of each shovel load with the proper correlations between them as well as between one load and the next being fully reproduced. Then different sampling schemes f or grade control or blending facilities can be examined on the simulated data. The mechanics of the simulation procedure and its potential applications are described in an example.IntroductionThe purpose of this paper is to illustrate the use of in-situ grade simulation in the planning o f the grade control in an iron ore min e. More precisely, given a production unit of given size, we need to know how many samples have to be collected in that unit so that we ca n recognize its grade with a reasonable precision. Conclusions that we would like to arrive at are of the type: with 4 blasthole samples we ca n get the iron grade of a 10,000 ton bloc k with less than a ± 2% Fe error 95% of the time.The approach t hat we take to solve this problem is simulation. We simulate the grade of samples and the grade of the block that contains these samples. We repeat the simulation for hundred s o f blocks. By comparing the sample grade with the block grade in each case, we determine the actual number o f blocks where the difference sample-bloc k is less than a given limit."

Jan 1, 1983

By F. Crundwell, N. Steenekamp

"The leaching of sulphide minerals generates a significant amount of energy. There are three systems that might be used to remove this energy. These are: cooling coils, quench water, and flash recycle. Flash recycle is the recycling of slurry from the autoclave to the feed tank. Heat is removed in this arrangement when the slurry at elevated temperature and pressure is flashed to atmosphere, releasing steam. The slurry is returned to the autoclave at lower temperature, resulting in cooling. The cooling is directly proportional to the steam released from the recycled slurry. Design equations and results for the flash recycle system are presented. A fourth proposal for removing heat is to recycle slurry from the back of the autoclave. These four alternatives not only remove the heat, but also have an effect on the leaching efficiency. Amongst the four alternatives, design calculations indicate that the flash recycle option is the optimal solution in terms of leaching efficiency and heat removal, and recycling product from the back of the autoclave is the worst. In spite of its efficiency in terms of heat removal and leaching, the implementation of the flash recycle system is limited to a few operations in the platinum industry.INTRODUCTIONIn considering ways to improve leaching operations, focus is placed on the chemistry, on the kinetics, the agitation and perhaps even on the gas mass transfer conditions. Attention is less frequently placed on the removal of energy from these reactors and how this might limit performance.The pressure leaching of sulphides releases a significant amount of heat. For example, the reaction for the leaching of chalcocite, Cu2S, given by"

Jan 1, 2012

By M. Rylatt, E. Legault-Seguin, C. Mohns

"With energy costs increasing and ore grades diminishing, the role of preconcentration in hard-rock mining operations has gained greater interest. Dense medium separation is a process that can be conducted at particle sizes from 250 to 0.50 mm with high separation efficiency, depending on liberation characteristics of the valuable minerals. Pilot-plant case studies conducted at the SGS Lakefield site are presented, including mineral systems such as spodumene, sulfide-bearing gold ores, and complex sulfide ores. These case studies demonstrate that, for amenable ores, mass rejection of 20–60% is possible while maintaining recoveries of greater than 90%.RÉSUMÉ Au vu de la hausse des coûts liés à l’énergie et du déclin de la teneur des minerais, le rôle de la préconcentration dans les exploitations minières en roche dure présente un intérêt croissant. La séparation (ou concentration) en milieu dense est un processus pouvant être mené sur des calibres de grains de 250 à 0.50 mm avec un rendement élevé de séparation, en fonction des caractéristiques de libération des constituants des minéraux métallifères. Sont présentées dans cet article des études de cas menées dans des usines pilotes du site de Lakefield de SGS, lesquelles incluent des systèmes de minéraux tels que le spodumène, les minerais aurifères sulfurés et les minerais sulfurés complexes. Ces études de cas montrent que pour les minerais présentant les caractéristiques de libération appropriées, il est possible d’atteindre un rejet en masse de 20 à 60 %, tout en maintenant des récupérations supérieures à 90 %.INTRODUCTIONPreconcentration is the process of rejecting gangue minerals while ensuring recovery of valuable minerals prior to more intensive, downstream processing. Preconcentration has been practiced in the industry for many years, and is gaining greater interest as the industry copes with processing lower grade, more difficult ores, which typically require finer grind sizes and incur higher energy costs.The benefits of preconcentration are:• lower mining costs, which allows for nonselective mining;• lower process capital and operating costs (e.g., resulting from reduced grinding, flotation, and fines disposal stages);• increased ore reserves, which provides the potential to treat lower grade ore;• increased mine production without expansion of the existing plant or concentrator;• reduced overall tailings impoundment by converting the reject into a byproduct (e.g., underground backfill or aggregate);• improved efficiency of downstream processes (e.g., silica removal in electric arc furnace feed, removal of softer sliming minerals prior to grinding);• potential application to brownfield operations and greenfield projects; and• a “green” process option, which reduces processing energy consumption;– reduces mill feed;– increases stage metal recovery (higher grade feed);– increases mill metal output per tonne processed;– reduces surface plant, tailings dump, and tailings pond requirements because the plant has a small footprint and can be installed underground; and– can be applied to retreatment of old tailings dumps to recover metal values and reduce environmental impacts (e.g., dissolved metal runoff, acid drainage)."

Jan 1, 2017

By Chi Zhang, Junyi Wu

"The use of permanent stainless steel cathodes for electrorefining and electrowinning of cathode copper had been introduced to the market long time ago and now is a well-accepted technology worldwide. During the last decades, the Chinese copper refinery industry had been growing rapidly and many large scaled production plants had been built. In the modern refineries, permanent stainless steel cathodes are introduced and used instead of traditional starter sheets. The most common steel grade used is austenitic stainless steel S31603 (316L/1.4404), while both S30403 (304L/1.4404) and N08904 (904L/1.4539) have been used depending on the actual working conditions, especially with regarding corrosion environment. While 316L permanent cathode functions well in many plants, different kind of problems, such corrosion and deformation, have been reported. There is therefore an increased need for more suitable material. New stainless steels, such as duplex stainless steels, with better properties have been tried and introduced into the application of permanent stainless steel cathode with satisfied results. The article introduces first the Chinese copper refinery industry and properties of duplex stainless steel in general, and then describes the development of using permanent duplex stainless steel cathode, including the actual working conditions, production of cathode sheets as well as the experiences of application in details. After more than one year’s usage, the advantages of permanent duplex stainless steel cathodes are clear seen.INTRODUCTIONChina has become a major player in the international copper market, accounting for around 40 percent of global refined copper demand. Despite the slowdown of the Chinese economy, the consumption of copper products will still increase, but with a medium and/or low growth which will be the new situation for the coming years. The average growth rate is expected to be around 5 percent per annual. In the coming Five-Year plan for National Economic and Social Development a number of initiatives will be finalized which will require massive amounts of copper. In 2015, the expected consumption of copper products will be over 9 million metric tons. The main driver of the consumption is the electric power industry which accounts nearly the half of the total consumption; followed by cooling application with 15% and transportation with nearly 10%, see figure 1."

Jan 1, 2016

By John Blackshaw

NEW sources of supply of tungsten concentrates became necessary when the flow from the Far East was blocked in 1942. In Canada, one source has been noted in the workings of the Hollinger mine at Timmins, Ontario. For many years, a small amount of scheelite had been removed with the gold ore, and an appreciable tonnage of scheelite still remained in the mine. At the request of the Dominion Government, a plant was built to recover this scheelite in the form of a concentrate that could be used by the alloy-steel industry without further preparation. The plant began operating early in March, 1942, and a small tonnage of ore, carrying scheelite and gold values, has been treated daily since then. The possibility of recovering the scheelite had been considered on several previous occasions. Each time the proposal had been given up because the total profits from the enterprise were estimated to be insufficient to repay the capital cost of building the recovery plant. At the time the plant was built, additional information had been gathered about the tonnage and grade of the scheelite ore in the mine, and several thousand tons of ore grading higher than 0. 25 per cent WO3 (tungstic trioxide) were known to be available.

Jan 1, 1943

Experimental determination of the response of an AG/SAG mill treating two components of significantly different impact resistance is challenging for two main reasons: firstly, small scale laboratory tests have yet to be confirmed as valid representations of the full scale milling environment, and secondly pilot plant testing requires 10-20 tonnes of ore per scenario which precludes the use of drill core, rendering the process very expensive. In order to mitigate these difficulties, modelling was considered as a potential way forward. However, as the JKSimMet AG/SAG model currently has no capacity to simulate the interaction of two ore types with differing impact resistance, density and/or feed size distributions, an alternative modelling approach was developed. This approach aims to essentially calibrate the AG/SAG process under a set of given conditions, for which survey data and the ore properties of the main components in the feed blend already exist. This paper describes a new conceptual model, which provides a simplified approach for investigating the multi-component behaviour of two ores of differing hardness/SG in a given AG/SAG milling environment, and which can potentially be used for scale-up from laboratory/pilot testwork and geometallurgical estimation of throughput.

Jan 1, 2012

"The Upper Mannville unit commonly consists of interbedded marine and non-marine sands and shales, but in northwestern Alberta the unit consists of marine shales of the Spirit River Formation. A thick tongue of marine shale (Clearwater Formation) ex-tends eastward into the Athabasca area below sandy Grand Rapids beds. Correlation of Upper Mannville rocks to the southeast is difficult, but in the Cold Lake area a thick sandy depositional cycle (Mannville ""C"" of this paper) appears to be approximately correlative with the Clearwater Formation. In the Lloyd-minster region, tongues of marine sedimentary rock occur in the lower part of the Upper Mannville unit. Most of the Upper Mannville oil occurs in the Grand Rapids Formation at Wabasca, in the thick ""C"" unit and younger Mannville sands at Cold Lake, and in the Sparky and General Petroleums sands of the Lloydminster region (Figure 2).The Lower Mannville unit was deposited on an erosional surface of considerable relief that truncated the Jurassic and older strata of the Western Canada basin. Continental, probably fluviatile, sedimentation persisted over much of the Western Canada basin during deposition of the Lower Mannville unit, but an Arctic or Boreal sea lay over part of northern Alberta. At the end of the depositional episode, the sea transgressed southward and eastward (Figure 3) and re-worked the Bullhead and McMurray sands of northern Alberta into the glauconitic Bluesky and Wabiskaw sands. Topography on the sub-Cretaceous erosion-al surface had a considerable effect on the deposition of the Lower Mannville (Rudkin, 1965), and the highest hills on this surface were not completely on-lapped by Lower Mannville sediments (Figure 3). The coarser elastic material was derived both from a western Cordilleran region and from an eastern Canadian Shield region (Glaister, 1959, p. 620; Mellon, 1956)."

Jan 1, 1966

By W. R. Cowan

The Caledon Outwash is a large deposit of glaciofluvial gravel and sand located 55 km north west of down town Toronto. For the most part it was laid down in a meltwater channel fronting the Paris Moraine about 14,000 years ago. Applying the braided bar model of Eynon and Walker (1974) the principal facies present are imbricated coarse gravels (bar corefacies); crudely stratified, imbricated bar top sandy gravels; and trough crossbedded side channel sands and gravelly sands. Of lesser importance are crossbedded bar front gravels, shallow braided stream facies gravels, and stoss side facies sands and pebbly sands (rare). Lithologically these deposits are characterized by FIGURE I. Geological relationships of Caledon Outwash. Industrial Minerals in Canada up to 95% Ordovician limestone and siltstone in the gravel fraction. A siltstone content of up to 34% requires that beneficiation be carried out for the production of better quality aggregates. Resources remaining are estimated to exceed 500 million tonnes in 3000 ha of the most suitable part of the deposit. Present production is about 4.5 million tonnes per year, shared by several producers.

Jan 1, 1984

By Earl Gebhardt

"The planning and design of mining panels in the Potash Corporation of Saskatchewan Inc., Lanigan Division mine Block B involved a number of investigative techniques. The techniques utilized to gain insight into the viability of mining included2-D and 3-D seismic surveys, longhole drilling, exploration wells, photo lineament, magnetic and gravity surveys, and actual room excavation.IntroductionPotash Corporation of Saskatchewan Inc. (PCS) owns and operates four potash mines in the province of Saskatchewan. The Lanigan Division mine is located 110 Ian east of Saskatoon, Saskatchewan, near the town of Lanigan.The Lanigan Mine commenced production in August 1968under the ownership or Alwinsal Potash of Canada Limited. The mine was purchased by PCS in 1977.Lanigan Division's productive capacity is 3.4 million tonnes of product per year. Ore is extracted from the "" B"" zone or Layer III or the Patience Lake member of the Prairie Evaporite, more than 1000m below surface . The Patience Lake member (approximately 20 m thick) consists of potash interbedded with salt. The average run-of-mine ore grade is 21070 K20 (Fig. I).The mine was initially developed using the room-and-pillar technique. Improvements in mining resulted in the use or extensible conveyors in long panel rooms."

Jan 1, 1993

By Daniel Hodouin, Robert Lanthier, Yve Dube

"A procedure f or constructing a grinding mill dynamic model is proposed. This model is used in a dynamic simulator of are grinding circuits. The simulator is designed for flexible flow sheets involving different grinding mills and particle classifiers and is able to accept several single variable PID control loops. The dynamic model is validated on a laboratory ball mill, and calibrated to an industrial installation. The simulator is used for characterization of grinding circuit dynamic behaviour and tuning of control strategiesIntroductionThe ore grinding operation is a critical step of the ore preparation process because it is the last comminution stage before the separation of minerals. The properties of the ground minerals to be concentrated, control the quality and efficiency of the separation process. This is why it is important to control properly the operation of the last grinding stage, commonly constituted of a closed circuit ball mill with classifier . To provide an adequate fine product, the grinding operation should compensate for the perturbations of the feed characteristics (size analysis, grindability, etc.). The main objective is to maintain a constant size distribution for providing stable operating conditions to the separation units. Simultaneously another usual objective is to operate the grinding circuit at a maximum capacity.Automatic control applied to grinding circuit s is the appropriate approach to improve its operation. Most frequently average optimal operating conditions are determined from steady -state performances of the circuit , and the automatic control is used for stabilizing the operation at selected values of the process variables . In the traditional approach, one or several single input! single output (SISO) control loops are implemented and empirically tuned. Advanced control practices'!' are based on a quantitative analysis of the circuit dynamics, which could also give a basis for the tuning of conventional SISO 100ps(2)."

Jan 1, 1987

By Robert B. Parsons

"Considering the traumatic events of Canadian mining taxation of the 1970s, one wonders at the sanity of anybody who tries to predict what the 1980s might hold for the tax structure of the mining industry. Yet, the author agreed to tackle this task when called upon to do so at the annual meeting of the Quebec Metal Mining Association in June. The text of this ""daring"" speech follows.IntroductionI have been asked to play the part of the oracle at Delphi, and to predict what the 1980s might hold for the Canadian mining industry in terms of taxation. To appreciate the challenge of this difficult assignment, try to imagine someone in my position back in 1972 attempting to forecast the balance of the 1970s. I daresay that ten years ago nobody could possibly have conceived of the devastating and casualty-ridden rollercoaster ride that mining taxation actually took in the 70s. Nevertheless, I shall examine the entrails and try to shed some light on what might happen during the balance of this decade as far as mineral taxation is concerned.If one were to retreat deep into history, one would find that taxation generally served one purpose-namely, to raise revenues for the government. More recently, an important second function has emerged: taxation is increasingly being used as a fiscal tool-a tool intended to mould and shape future events in order to accomplish certain economic, social and political objectives. It is these two main forces-the need (or desire) for revenues and the perceived convenience of using taxation as a fiscal tool-which will continue to shape the tax structure of the future.In our assessment of where taxation of the mining industry may be headed, we should be able to learn something by looking at where we have been."

Jan 1, 1982

By J. B. Morrow

Methods of Coal Preparation Fundamentally, the object of coal preparation is to increase, economically, the value of a fuel by making it more suitable to the uses of the consumer. This can be accomplished in three major ways: 1.Screening or sizing 2.-Mixrng or blending 3.-Cleaning By combinations of any or all of these methods we can prepare coal to meet standard specifications-a process of standardization which is the more desirable the more nearly it approaches the unvarying quality of packaged goods, where the package you buy today and tomorrow is the same as that you bought yesterday. It should be noted that it is readily possible to get good cleaning and still have poor preparation because of faulty screening and mixing, and, on the other hand, it is possible to get a passable grade of cleaning, combined with good screening and mixing facilities.

Jan 1, 1931

By Jerry Gagnon, Matt Burr, Timothy Ellis, Abbas Mirza, Larry Webb

"The mechanical properties of RSR anode alloys (lead-calcium-tin, 009+ and lead-strontium-tin) were investigated as a function of time with an objective of developing lead anodes for use in high temperature electrolytic processes such as in copper liberator cells and in cobalt and nickel electrowinning. At a temperature of 70 oC, the mechanical properties of rolled RSR lead-calcium-tin (PbCaSn) alloy currently used in copper electrowinning decreased gradually while the mechanical properties of rolled RSR lead-strontium-tin (PbSrSn) decreased relatively quickly and stabilized at low strength levels. Cast PbSrSn started off as the weakest alloy but its properties remained stable with time. Rolled RSR 009+ anode alloy showed improvement in ageing properties over the other alloys tested. However, its mechanical properties did not stabilize in the study timeframe of 284 days. Further investigations are planned to study the effect of alloying elements on mechanical properties of RSR 009+ anode alloy over several years as a function of time at 70 oC. The mechanical properties will be evaluated to determine the time at which they stabilize. Comparative plant trials with rolled RSR PbCaSn and RSR 009+ will also be performed in copper liberator cells and in cobalt and nickel electrowinning tankhouses to determine their mechanical and electrochemical performance at temperatures of 65-75 oC.INTRODUCTIONLead-based alloys are the primary anodes used in the electrowinning of copper, zinc, nickel, cobalt and manganese from sulfate-based aqueous systems. Lead anode technology has evolved over the years migrating from pure lead and lead-antimonial alloys to the present day PbCaSn alloys for copper and PbAg and PbCaAg alloys for zinc electrowinning (Prengaman, Ellis and Mirza, 2010). It has also migrated from cast to rolled microstructures in search of improved mechanical properties and higher corrosion resistance. Although great strides have been made in the development of new lead anode alloys and production processes for lead anodes to be used in copper electrowinning, the industry still has some unresolved issues. These relate to the necessity of having higher mechanical properties especially for the lead anodes in liberator cells in copper electrorefining and for cobalt and nickel electrowinning as these tankhouses operate at temperatures of 65-75 oC compared to 40-45 oC in case of copper electrowinning."

Jan 1, 2016

By P. Rocque, S. Talebi

Although the measurement of blast vibration close to the blasthole is critical to the understanding of rock fragmentation mechanisms and blast damage in the rock masses, limited experience for such monitoring exists. Because much higher vibration amplitude and frequency ranges are expected in rock masses close to an explosive charge as compared to far field vibrations, different problems from those for the far field monitoring must be considered for near field blast vibration monitoring. Currently, guidelines for design of the near field blast monitoring systems do not exist. This paper describes the development of an integrated technique for vibration monitoring close to a blast hole, including selection and installation of transducers, design of a monitoring system and signal recording. A densified cement was designed for grouting accelerometers in order to match p-wave impedance between the rock and grout. The monitoring technique described has proven suitable for blast vibration monitoring within 2 m to 15 m of a blast hole having loading conditions similar to production blasts.

Jan 1, 1993

By Sukumar Bandopadhyay, Arunapuram Sundararajan

"For the last three decades, the application of network planning has provided a basis for a formal and general approach to the discipline of project management. For fixed activity duration, a very simple algorithm commonly known as critical path method (CPM), gives the length of time required for the total project as well as indicates the activities which are vital to the completion of a project. Project Evaluation Review Techniques (PER T) on the other hand, generalize the above approach to recognize uncertainty in the activity durations by allowing them to be random variables. One of the misleading aspects of current "" PER T"" solution method is, however, the implication that there is a unique critical path. In general, any number of paths could be critical, depending on the particular realization of the random activity durations that actually occur. In this case, simulation can be utilized to estimate completion time of a project.In this paper, the concept of criticality indexing is discussed, and a simulation model application which defines the critical path based on the criticality indexing concept, to a longwall development - extraction network, is presented. The model also provides suitable scheduling of resources based on the resource constraints and smooth s out period-t o-period assignments. IntroductionThe successful management of large-scale projects require careful planning, scheduling , and coordinating numerous interrelated activities. To aid in these task s, formal procedures based on the networks and network techniques (variously called PERT or CPM) were developed. In its original form the completion time for individual activities of a project was assumed fixed and known in advance: this in turn led to the familiar algorithms for computing the critical path, earliest start time, slack, and so forth. The unreality of such an assumption is, of course , apparent in many contexts. Consequently, attempts were made to introduce probalistic activity completion times, allowing representation of the stochastic nature of most projects."

Jan 1, 1987