Search Documents

By Truan-Sheng Lui, Li-Hui Chen, Fei-Yi Hung, Cheng-Yi Chen

"This research used the austempering heat treatment on the SCM435 thin specimen with a type of double loop and obtained the Cr-Mo bainite structure, and then we could further investigate the mechanical properties of SCM435 bainite structure. Experimental data showed the stability of the mechanical properties of specimen with austempering temperature 830°C for 25 minutes was better than that of 15 minutes. The size of austenite grain affected the strength of thin specimen. After austempering at 830°C-25minutes and salt bath at 290°C, the stability of UTS was better than that of salt bath at 310°C and 330°C. The average hardness of all specimens was about more than HRA70. The specimen with austempering at 830°C-25minutes and salt bath at 290°C-30minutes had bigger grain size of austenite and retained y, it also had higher hardness and strength toughness. So, its stability was improved for tensile strength comparing with traditional tempered martensite process.IntroductionSCM435 is a Cr-Mo steel with high strength and high hardness properties, and it has been widely used in machine parts, shafts, gears and strength screw products [1-3]. However, this system often has lower reliability due to the brittleness of high-temperature tempering and quenching inequality. Considering the austempering heat treatment can obtain the uniform bainite structure to improve the temper brittleness, and the austempering heat treatment is a continuous process that it also has efficiency and uniformity. For the thin plate specimens, the mechanical properties of the bainite structure are better than traditional martempering structures."

Jan 1, 2013

By Enrique Munaretti, Cathy Aimone-Martin, Vitor Rosenhaim, Jair Koppe

Production blasts at one of Copelmi’s coal mine operations will be carried out 100 m (330 ft) from a neighborhood located in the town of Butiá, southern Brazil. Mine management is concerned about the possibility of damages and complaints due to blasting operations at close distances to structures of substandard construction. Blasting in the area is characterized by the use of very low powder factor resulting in confined shots in which movement is restricted to a point of almost undershooting the rock. Over the past year, tests were conducted mainly in the overburden area to determine the best approach to be implemented when blasts move closer to the town. Mine management wants vibration levels to be reduced lower than the damage limits proposed by Brazilian regulations to ensure a safety margin and mitigate perception by the community hoping to reduce the number of complaints.

Jan 1, 2013

By Andy Judge

"In traditional Permanent Magnet Machines, such as electric motors and generators, power is transmitted by magnetic flux passing through an air gap, which has a very low magnetic permeability, limiting performance. However, reducing the air gap through traditional means carries risks in manufacturing, with tight tolerances and associated costs, and reliability, with thermal and dynamic effects requiring adequate clearance. Using a magnetically permeable, high thermal conductivity material has the potential to improve magnetic performance, while at the same time offering performance advantages in heat transfer.Ferrofluids can be used to improve permeability in the rotor I stator gap. However, there are several tradeoffs in this approach. Fluid immersion comes with an increase in fluid friction loss compared to the windage losses of a traditional system. Isolating the rotating components from the ferrofluid can offset this effect. Also, while the magnetic effect can be positive for gap permeability, leakage flux can increase, and saturation can limit gains. These effects must be taken into account for a system optimized for ferrofluid immersion.IntroductionPermanent Magnet Machines (PMM's) convert electrical energy to mechanical energy in motor applications, or, for generator applications, convert mechanical energy to electrical energy through means of passing alternately polarized magnets past electrical coils. Looking at a simplified version of a PMM, where Rx is magnetic reluctance and <l>x is magnetic flux, we have the circuit shown in Figure 1."

Jan 1, 2013

By T. Johnson

Hydrometallurgical processes can be exceptionally corrosive. This is particularly true in acid leaching processes for copper, cobalt, nickel and rare earth elements. In the last five years, several large hydromet plants have been built in North America (Vale - Long Harbour, Baja Mining ? El Boleo and MolyCorp - Mountain Pass). Hundreds of storage tanks, extraction vessels and electrowinning cells along with miles of piping were designed and fabricated to withstand the aggressive environments inherent in these processes. One key element all three projects had in common was the extensive use of FRP in equipment design. As a material of construction, FRP provided equal if not improved durability relative to alternative corrosion resistant alloys at a considerably lower cost. This paper will highlight the extensive use of FRP in these three world scale projects and why it was chosen for each process.

Jan 1, 2013

By Min Zhu, Yu Ji, An-chao Ren

"After being welded in the weld plant, the 100-meter heavy rails with the specification of 60kg/m are found broken during the straightening process in four planes. Failure analysis is made using the optical microscope and SEM with the result showing that the broken rail contains the imperfection of protrusion which exists at the edge of rail foot, about 1 00mm away from the rail end. When the protrusion is peeled off by deseamer from rail surface, cold scratch is generated which causes the rail to be broken during the subsequent straightening process. By adjusting the roll diameter differences between top and bottom roll of universal finishing mill and the height of pass line, it is possible to maintain the rails flat when leaving the mill. This prevents the upsweep and downsweep phenomena and, thus, the imperfection of protrusion can be eliminated. IntroductionThe development of rail transit worldwide has entered into a new era since the 1960s. The hi-tech rail transit system has gradually gained recognition over the world. In particular, the emergence of new-type passenger trains represented by TGV of France, ICE of Germany and Shinkansen of Japan and heavy haul trains as well, has revealed the charming way and more prosperous future of the modern and hi-tech rail transit system to the people all over the world. It should be pointed out that rail transit system is still the most effective solution to traffic jams among urban cities and in the central cities during the 21 '1 century, especially high-speed railway and subway which take overwhelming advantages over air transport, marine transport and road transport in terms of high speed, high efficiency, safety, comfort, environment protection and high flow. With the trend of increasing speed and heavier load of trains, higher product quality of rails is demanded. The rails for passenger dedicated lines require high cleanness, high accuracy in size, high flatness, high surface quality and large size (100-meter fixed length). The rail quality has direct influence on the operating performance of rail and railway traffic safety. The 100-meter heavy rails with the specification of 60kg/m are broken subject to the straightening process in four planes after being welded in the weld plant. This paper analyzes the reason for rails being broken and provides the theoretical proof for determining the rolling process."

Jan 1, 2013

By Hongli Wen, Guangkun Shen, Qiong Deng, Xuling Chen, Min Gan, Xiaohui Fan

"In this research, pyrite cinder which contains 53.51% Fe and 0.54% Pb was processed by magnetic roasting separation to obtain a concentrate with 64.62% Fe and 0.56% Pb. The concentrate was then leached with hydrochloric acid to remove lead. Several technological parameters which may influence the removal efficiency were investigated: the mass fraction of hydrochloric acid, pulp density, the leaching time and temperature. On the conditions that the mass fraction of hydrochloric acid of 5%, pulp density of 30%, the leaching time of 30 minutes and leaching temperature of20°C, the lead content in the concentrate was reduced to 0.19%. The product was suitable for agglomeration and pelletization. Through the analysis of the lead distribution and phase change during the whole process, the mechanism of lead separation from pyrite cinder was analyzed.IntroductionPyrite cinder is rich in iron, which defines its most extensive and effective use as raw materials for iron making. However, some pyrite cinders contain much non-ferrous metals, which is detrimental for the iron making process. Lead, one of the harmful elements, will destroy the blast furnace lining. Besides, it causes pollution of the environment[1]. Therefore it is necessary to remove excessive lead before entering the blast furnace. To separate the lead from pyrite cinder, much research was done, including flotation, high temperature evaporation and leaching. High temperature evaporation consumed too much energy. The flotation was difficult to obtain high- grade iron ore concentrate[2]. Majority of the leaching was direct leaching of pyrite cinder, which was also difficult to get high-grade iron ore concentrate[3]. This article explored the magnetic roasting method to get high-grade iron ore concentrate, acid leaching method of the concentrate to remove excessive lead, providing guidance for the efficient utilization of pyrite cinder."

Jan 1, 2013

By Roberto Folchi, Hans Wallin, Mara Battocchio

An understanding of explosives science and technology, and the competence to harness it is central to maintaining Explosives capability, national security, and in sustaining a competitive industry. A consequence of eroding this competence is the increased likelihood of explosives accidents. These are often catastrophic as demonstrated by accidents in Nigeria, Russia, Toulouse and Enschede. In addition to the serious loss of life there was the very significant damage to houses, domestic and industrial infrastructure and to the environment at a cost of many millions of Euros.

Jan 1, 2013

By Jilai Xue, Jun Zhu, Baisong Li

"TiB2-C/C Function Gradient Materials (FGM) is used in cathode materials to improve aluminum wettability and melt penetration in aluminum electrolysis. In this investigation, FGM was tested for use as part of the cathode materials, where a 10 mm thick TiB2-rich layer was on the top as an Al-wettable surface, the TiB2-C layers in the middle as a gradient layer and the carbon on the bottom as a base. Electrical resistances ofFGM were determined in the temperature range of25- 9600C in argon atmosphere. The results show that the present of TiB2-C gradient layer can reduce the open porosity and the electrical resistance of the cathodes materials at elevated temperatures. The cathode samples after aluminum electrolysis usually demonstrates an increase in electrical resistance, but the application of FGM layer can compensate such an increase for certain extend due to less variation in porosity and lower the level of melts penetration.IntroductionCarbon is still used for aluminum reduction cathodes dominantly, but it has a poor wetting properties by liquid aluminum and the anode-cathode distance has to be kept about 4-5cm with an additional 1.3-2.0 V voltage drop [l]. TiB2 has better wettability by liquid aluminum with higher electrical conductivity and stronger chemical resistance to the electrolyte attack. And the wettability ofTiB2-C composites cathode on liquid aluminum can be also improved, while liquid aluminum can completely wet the cathode surface ifTiB2 content exceeds 27% [2-4]. However, during the process of TiB2-C composites cathodes preparation and aluminum electrolysis, the deformation by temperature variation or sodium penetration are great disparity between TiB2 and carbon due to their physical properties difference. This will accelerate the cathodes cracking and deterioration."

Jan 1, 2013

By Biao Zhou, Qian Li, Kuo-Chih Chou, Yi-Long Liang, Jie-Yu Zhang, Qun Luo

"In this work, the phase transformational behaviors and microstructural characteristics of 60Si2CrVAT spring steel were systematically investigated as a function of applied cooling rates in the range of 0.l-10°C/s. A quenching deformation dilatometer was used to austenize and quench. The dilatometric curves between length changes and temperature of samples suggest three characteristic stages could be identified as different ranges of cooling rates, which meets well with metallographic examination and the measured hardness results. As the cooling rate increases, the structure transformed from pearlite, granular bainite to finally martensite. The F + P and B zones are completely overlapping in continuous cooling transformation (CCI) curve, which indicates that this steel is difficult to become single bainite and shows good hardenability.IntroductionThe 60Si2CrVAT, a high-carbon low ally super-high strength steel developed from the ?OCT 60C2XFA and 60Si2MnA, is often used for coil spring of heavy vehicles and high-speed railway by hot deformation or cold deformation [1-3]. The addition of Si improves relaxation resistance significantly, through the refinement of tempered carbides as the result of the retardation of E -carbide conversion to cementite during tempering. Due to its deleterious effects on decarburization and toughness, the maxinJum content of Si has limited to 1.5 or 2.0% [4-5]. Additionally, V and Cr can improve sag resistance due to the precipitation of fine carbonitrides during hot rolling [6-7]. To best of our knowledge, the strengthening by precipitation of alloy carbides of Cr and V often referred to secondary hardening [8]."

Jan 1, 2013

By Charles S. Spirakis

The consistent occurrence of organic carbon early in the paragenesis of Mississippi Valley-type sulfide deposits suggests a genetic link between organic carbon and the sulfide ores. Reduction of sulfate in the mineralizing solution by organic carbon at the sites of mineralization is commonly proposed as the precipitation mechanism for these deposits, but inorganic sulfate reduction is too slow to be important to the chemistry of the ore zone, and bacteria, which catalyze sulfate reduction at low temperatures, are not known to survive at the temperatures of mineralization. Sulfate reduction with or without bacteria is not consistent with the sulfur Isotope evidence. Sulfur isotope studies also indicate that the derivation of sulfur from hydrocarbon at the sites of mineralization is unlikely. Organometallic complexing may be involved in the transport of metals, but no plausible mechanism for breaking these complexes at the sites of mineralization has been proposed. Reduction of partly oxidized sulfur species in the mineralizing solution by organic carbon at the sites of mineralization is a possibility which deserves further scrutiny.

Jan 1, 2013

By Thomas A. Printz

The wide use of carbon steel in construction and engineering projects makes this engineering material accountable for approximately 85% of the total annual steel production worldwide. Despite the lack of corrosion resistance of carbon steel, it is incorporated into the permanent work for marine applications, power plants, transportation projects, chemical processing, mining, petroleum production and refining, pipelines, mining and construction equipment. Corrosion is an electro-chemical process that occurs in the presence of water and air. When an electric current is introduced to water or soil, the rate of carbon steel corrosion increases rapidly. Gaseous atmospheric constituents that are capable of electrolytic activity can also increase the rate of corrosion. Corrosion tends to be more rapid in environments in which the steel is exposed to water, and then air, rather than being constantly submerged. The exposure to seawater increases steel pitting because the electrical conductivity is improved in salt water.

Jan 1, 2013

By Armin W. Stuedlein, Seth C. Reddy

In this study, factors affecting the reliability of augered cast-in-place (ACIP) piles under axial compression at the serviceability limit state are addressed using a simple probabilistic hyperbolic model and a database of load tests on ACIP piles in cohesion less soils. The aleatory and model uncertainty in a selected load-displacement model is statistically characterized, and is used to simulate representative random samples from the bivariate random vector of model parameters. A first-order reliability method (FORM) was used to determine the effect of sample size on the stability and uncertainty of the reliability index. Sample sizes greater than about 40 provided relatively consistent estimates of the reliability index; however, its uncertainty continued to decrease with increasing sample sizes. Additionally, the effect of slenderness ratio on the reliability of the serviceability limit state design was characterized and found to exhibit a significant effect on the probability of exceeding a specified displacement.

Jan 1, 2013

By Carlos Maurício Fontes Vieira, Sergio Neves Monteiro

"A ceramic body traditionally used to produce bricks and roofing tiles with kaolinitic clays was reformulated by the addition of sand and illitic clay. The objective was to obtain a ceramic product with better technological properties. Specimens were made by uniaxial press-molding at 20 MPa and then fired at 850, 900 and 950°C. The determined technological properties were: linear shrinkage, water absorption and flexural rupture strength. The results showed that both sand and illitic clay contribute to reduce the water absorption of the industrial clayey body. With respect to the flexural behavior, it was observed that the incorporation of sand decreased the mechanical strength. On the other hand, the illitic, incorporated in an amounts of 30 wt.% contributed to increase the mechanical strength of the clayey ceramic.IntroductionCeramic bodies industrially fabricated in the county of Campos, north of the State of Rio de Janeiro, in Brazil, are still empirically elaborated using a mixture of local clays. These clays are predominantly kaolinitic mineral in nature, associated with high plasticity and elevated weight loss during the firing stage. Due to the excessive plasticity of the ceramic bodies, dimensional defects, which occur after drying and firing are usually obtained. Moreover, the kaolinitic nature and the presence of aluminum hydroxide (gibbsite) confer a refractory behavior to the local clays, which impairs sintering during the firing operation. In the case of clay ceramic products for civil construction, this results in greater porosity associated with elevated values of water absorption and low mechanical strength [1,2]. To avoid these problems, it is necessary to reformulate the ceramic body composition. The addition of both non-plastic materials to reduce plasticity and fluxes to condition the refractoriness is a possible alternative.As an alternative to reduce the plasticity of clayey ceramics sand, which is predominantly constituted of silica, can be used. The incorporation of sand in amounts of up to 25 wt.% to a clayey ceramic body used for roofing tiles fabrication was studied by Vieira et al. [3]. In that work specimens were prepared by extrusion and fired at 850°C. The results indicated that in the pre-firing stages the sand improved the workability of the investigated clayey ceramic body and facilitates the drying stage. It was also observed that the incorporated sand significantly improved the physical and mechanical properties of the clayey ceramic after firing. On the other hand, the apport of flux oxides could be done by the use of illitic clays that have a higher amount of alkaline oxides in comparison with the kaolinitics clays."

Jan 1, 2013

By Yamei Han, Jiang Du, Jinhui Peng, Mengbi Fu, Libo Zhang, Zhengfu Zhang

"A continuously pilot synthesis by microwave-heating was used in preparing the cathode material LiNi113Co113Mn11302 for Li-ion battery, which used Ni1/3Co1/3Mn1/3(0H)2 and LizC03 as raw materials. Decomposition of the raw materials and synthesis of LixNi113Co113Mn11302 would be fmished in single roasting process. In addition, using microwave-heating would reduce the reacting time largely. Furthermore, the yield of LixNi1/3Co1/3Mn1/302 synthetized in single roasting process was 50 kg. Meanwhile, the effects of Li:(Ni+Co+Mn) molar radio (Li:(Ni+Co+Mn)=l.06, 1.075, 1.09, 1.15) was studied in this paper. XRD, SEM and EIS were used in characterizing the cathode material. The results showed that the best Li:(Ni+Co+Mn) molar radio was 1.075. It was found that the LiNi113Co113Mn11302 synthetized with Li:(Ni+Co+Mn)=l.075 had homogenous distribution of particles and ideal layered structure. The galvanostatic charge-discharge(O. l C, 2. 75-4.3V, vs. Lt /Li) tests showed that the initial discharge capacity of the LixNi113Co113Mn11302 was 159.5mAh·g-1, and the discharge capacity was 157.6mAh·g·1after10 cycles.IntroductionRecently, as the cobalt was expensive and the restriction of dynamic power, the commercial cathode Li2Co02 which was expensive, toxic, and high pollution had exposed its defects[1·2l. Since T.Ohzuku[3l first reported the layered LiNi113Co113Mn11302, this material had high reversible capacity and caused the attentions of researchers[4l. Its reversible capacity was l 60mAh/g and 200mAh/g in the voltage range of 2.75-4.3V[5-61. But for the present, preparing LiNiwCowMnw02 by traditional had lots of disadvantages, such as the long heating time, the high cost and the volatizing of lithium and so on[7-9l. According to these, traditional prepatation wasn't good for sustainable development and energy conservation."

Jan 1, 2013

By Jilai Xue, Jun Zhu, Germain Kouma Ndong, Qiaochu Liu, Luxing Feng

"High-temperature oxidation and corrosion behaviors of Ni-Fe-Cr alloy as inert anodes for aluminum electrolysis have been studied in oxygen and molten electrolyte. The oxidation and corrosion scales on the anodes tested were analyzed using XRD and SEM-EDS. The oxidation rate is found to increase with increasing temperature from 700 °C to 950 °C, which can be approximately described by an inverse power rate function. The oxidation scales at 750 °C, 920 °C and 950 °C contain Cr-rich phase along with FeCr204 and (Feo.6Cro4)203. The corrosion extent of Ni-Fe-Cr anodes in electrolyte is dominated by temperature, which can make the scales thickness double from 700 °C to 750 °C or from 920 °C to 950 °C. Cr and Fe in the scales on the anode in electrolysis corrode preferentially into the molten electrolyte, while the nickel oxides could better sustain the corrosive environment in electrolysis. The results can be useful for developing inert anode material for potential application in aluminum electrolysis.IntroductionThe development of an inert anode for aluminum electrolysis has been a long term goal for aluminum industry. The present process for primary aluminum production involves the reduction of alumina with carbon anodes, forming carbon dioxide:"

Jan 1, 2013

By A. Butler

This paper explains the politics of mine nationalization in contemporary South Africa. Nationalization and privatization typically occur in the oil, mineral resources, and state utilities sectors, and they tend to follow one another in a long-term cyclical pattern. The paper explains why the current international environment has encouraged demands for nationalization and other forms of ?resource nationalism? in the South African minerals sector. It goes on to describe how the resurgence of resource nationalism has been influenced by internal factional politics in the African National Congress. It concludes that nationalization is unlikely to be the outcome of current policy deliberations within the ANC.

Jan 1, 2013

By Binxu Zeng, Mark Jolly, Xiaojun Dai

"The traditional investment casting foundries use batch melting and chunky running systems to produce casting components. This method leaves the energy saving issue as subsidiary one. In our research project, one of the partners, the AEROMET international PLC provides the thin wall aluminium component ""filter housing"" for test. The AERO MET uses traditional casting route to produce the filter housing, which only gives 5% --10% yield. In this paper, numerical simulation method is used to analyse filling and solidification of the casting running system. The CRIMSON running system of the filter housing is designed by using casting simulation software, MAGMAS and Flow3D. By working with AEROMET, various configurations of the casting running systems were tested and analysed. Using them ultiple life cycle approach, the energy content of new process is compared with traditional one. It indicates that the CRIMSON process only uses 36% of energy consumed by the traditional route.IntroductionThe investrnent casting is a metal for ming process using expendable patterns, which is a standard casting technique and is widely used to produce quality parts. Its accuracy, versatility and integrity tie itself to important and precious engineering components in Aerospace industry. However, traditional investrnent casting process usually uses chunky runner system and gravity filling method. It not only reduces the casting yield of the product but also causes the pouring defect during the casting. As author's previous research showed that gravity filling method pouring basin and down sprue are two main resources of entraimnent defects generation. No matter how good the running system is, entraimnent defects such as double oxide films (DOF) and bubbles will I get into the casting to cause problem."

Jan 1, 2013

Decision-making regarding plant-scale reagent dosage regimes and air rates is a topic of ongoing investigation and high importance. The current work explains some techniques that have proven useful in deciding on plant-scale flotation operating regimes. Specific focus has been placed on the reagents: frother and depressant, as well as some discussion around the control of air rate and froth depth. Air rate has been selected based on its effects on the froth phase. Froth velocity and froth height above the cell lip are the two variables measured and used to select the operating air rate. Pulp level is then adjusted to increase or decrease mass pull. A technique has been developed using the Anglo Platinum Bubble Sizer on an industrial flotation cell to determine the relationship between bubble size and frother concentration. This technique has been extended to measure the equivalent frother concentration or frothabilities of various streams on a rougher bank. A mass balance for frother was performed successfully, and this provided a better understanding of the way frother moved in the rougher bank. With this knowledge, more informed decisions can be made about frother addition required in subsequent flotation stages. For depressant, a new protocol for deciding on dosage rate has been developed. The depressant dosage should be based on the amount of fresh feed material reporting to a bank. Currently 400 g per ton of fresh feed has been assumed a reasonable starting point, with promising results. Improved froth stability and grades were observed. There is scope for more accurately defining the optimal dosage rate. Importantly, the combined effect of changing the chemistry and the hydrodynamics together has been demonstrated. A significant upward shift in the grade-recovery relationship for a cleaner bank was observed.

Jan 1, 2013

By Maria Kuttig, Christian Ruback, Gerhard Tober, Petra Maier

"It has been demonstrated that there is a strong relationship between work hardening with various post heat treatment and cyclic deformation behavior of structural steel S275. This study contributes to a project developing a process for the complex forming of steel, which combines rolling and bending. Due to the complex geometry of the final work piece, the deformation degree varies greatly. The forming temperature, as well as post heat treatruent, influences recrystallization processes in dependence of the local deformation degree, resulting in inhomogeneous microstructure of the work piece, which affects the quasi-static and dynamic properties. Cyclic creep and hardening or softening has been monitored during constant amplitude loading at stresses near fatigue strength in normalized condition. Work hardening, stress relief or recrystallization influence the cyclic deformation behavior and produces cyclic creep effects. Cyclic softening or hardening and creep were observed to occur in parallel. To what extent these properties are noted depends on the deformation degree.IntroductionThis work is part of a research project developing a new process for the three dimensional forming of steel. For the final product the fatigue strength influenced by the forming parameters is very important. Due to its complex geometry, the formed final plate has different deformation degrees. This leads to different recrystallization behavior and heat treatruent will have different effects on the microstructure. The peak deformation degree cp of the plate will be around -0.5 what leads to the analysis using rolling from 22 mm to 13 mm of thickness. The quasi-static material properties are very important for calculating the preliminary design. However, work pieces which are cyclic loaded need fatigue tests to describe the in-service material behavior. [l] For the prediction and to guarantee the wanted life-time of the part cyclic deformation tests are important. [2, p.23-32] When it is assumed that the work piece will only loaded in cyclic tension, fatigue testing will be done from zero to a maximum force value. In preliminary tests this value is the tensile fatigue strength from a Smith diagram. During processing, here forming, work hardening takes place resulting in strengthening. Therefore, in further tests maximum load can be increased to monitor cyclic deformation mechanism in more detail. However, to study cyclic creep and hardening and softening data should be evaluate over sufficient life time and should not fracture too soon."

Jan 1, 2013

Mine planners must select a single pit for design with the knowledge that the grades on which this selection is made are uncertain. This uncertainty is often ignored through the use of deterministic models of grade. This makes the mine planner?s job simpler but does not necessarily lead to the ?correct? or ?best? selection. Grade uncertainty is typically modeled with conditional simulation, which generates multiple possible realizations of grade that are equally probable (or improbable). M ethods for incorporating grade uncertainty into mine planning to date have either been perceived as being too complicated, not accessible or too time-consuming. This paper proposes a simple and efficient modeling approach to incorporating conditional simulation into pit optimization, which would be able to be applied in currently commercially available software. An example for R esolute M ining Ltd.?s Syama gold project in M ali shows the range of ore, grade and value outcomes associated with generating pits through a variety of methods.

Jan 1, 2013