Search Documents

By W. M. Ma, Daniel W. H. Su, K. Centofanti, Yi Luo, W. L. Zhong, Syd S. Peng

3.1 INTRODUCTION The final subsidence basin discussed so far is that developed long after mining has stopped. In a supercritical final subsidence basin, the central portion subsides uniformly. Thus any structures located there are not subjected to any final permanent surface deformation. But this statement is only true for the final subsidence basin. When the face is moving, the structures are subjected to dynamic deformations associated with the dynamic subsidence basin. For instance the house in front of a moving face (location 1 in Fig. 3.1) is subjected to the maximum tensile strain and the maximum positive curvahue. When it falls behind the face in location 2, it is subjected to the maximum compressive strain and the maximum negative curvature. When the house is far behind the face in location 3, it returns to its original condition with only uniform subsidence. However, the magnitude of the dynamic deformations may be sufficiently large to damage a structure in locations 1 and 2 before it reaches location 3. Therefore it is very important to study the characteristics of the dynamic subsidence basin. Under normal conditions, when the face has advanced for a distance approximately one-sixth to one-third of the seam depth from the setup entry, depending on the seam depth and the physical properties of the overburden strata, the movement of the over- burden strata reaches the surface, whereupon the surface also be- gins to deform. Thereafter, the surface point where the movement initiates is always located at a fixed distance ahead of the face. The angle between the vertical line at the faceline and the line connecting the movement initiation point on the surface and the face- line is the angle of advance influence, w. The angle of advance influence can be used to determine the distance, [ 1], which is the influence zone ahead of the face. w is approximately 20O to 35 O for the northern Appalachian coalfield (Peng and Geng, 1984). The movement of each surface point is a relatively complicated process both in time and in space, because the relative position between the faceline and each surface point varies continuously, so that the direction and rate of movement for each surface point differ. In the following sections, the movements of each surface point on the major cross section are illustrated. 3.2 DYNAMIC SURFACE MOVEMENTS Dynamic surface movements include dynamic subsidence and displacement. The movement of each point on the subsidence basin is different as the face advances from 1 to 6 (Fig. 3.2). Surface points A and B, being far in front of the moving face, subside and displace toward the face (i.e., from A to A' and from B to B'). Point C, which is quite near but in front of the moving face, subsides continuously but displaces initially toward the face and then turns to pure subsidence ending up at C'. Point D, which is behind the face above the gob, subsides continuously, but displaces initially toward the face when it is in front of the face and reverses to follow the moving face when it is behind the face, with the amount of displacement toward the face being larger than that following the face. As a result the net displacement is toward the center of the gob (i.e., from point D to D'). The same statement is true for point E. For point F, the net displacement is zero, i.e it appears to have dropped down vertically to F'. For points G to I, the net displacements are in the direction of face advance except the magnitudes are increasing in sequential order. Point 1, has reached the final dynamic position of 1'. In other words, the face has passed sufficiently away such that it does not affect the movement at point I. All other points (A to H) are still within the face influenced area. 3.3 DEVELOPMENT OF DYNAMIC SUBSIDENCE PROFILES When the face has moved for a distance of h/6-h/3 from the setup entry, surface subsidence reaches the surface. At this time the surface subsidence basin is very mild (S, in Fig. 3.3), and it is symmetrical about the center. As the face continues to advance, the maximum subsidence continues to increase, and its location moves with, but falls farther behind the face. When the face has advanced a sufficient distance, e.g., (0.9-2.2)h, away from the setup entry, the maximum subsidence reaches the maximum possible value (curve S,). At this time, the dynamic subsidence profile is fully developed. Thereafter both sides of the dynamic subsidence profile become stabilized. The subsidence profile on the face side moves with the advancing face in an orderly manner (curves S, and S,). When the face stops, the face side of the profile continues to subside and becomes stabilized (curves;) sometime after. Curve S; is the final subsidence profile (see Fig. 2.22). 3.4 DEVELOPMENT OF DYNAMIC DISPLACEMENT AND SLOPE PROFILES The dynamic displacement profile moves with the advancing face (Fig. 3.4), but changes according to some specific rules. When the face has advanced to A, the surface begins to move and its dynamic displacement profile has two maximum values (curve Ua): one positive near the setup entry moving toward the face advancing direction and the other negative on the face side also moving toward the face advancing direction. As the face continues to advance, the positive maximum displacement on the setup entry side increases and moves toward the face continuously. The same statement is true for the negative maximum displacement on the face side. When the opening increases to the critical size, both the maximum positive and negative displacements reach the peak values and remain constant thereafter. Notice that when the opening becomes critical in size, the point of zero displacement no longer moves with the advancing face. Rather it spreads into an area of zero displacement (curve Ue) and expands as the face advances. When the face stops, the displacement on the face side continues until it becomes stabilized (curve Úe). Curve Úe is the final displacement profile. The ratio of maximum dynamic to final displacement ranges from 60 to 75%. The dynamic slope profile follows the same patterns of change. The ratio of maximum dynamic to maximum final slope ranges from 50 to 80%. The maximum slope decreases with in- creasing rate of face advance (Peng and Geng, 1984). It must be pointed out that except for those near both sides of the profiles, each point on the displacement and slope profiles is subjected to a cycle of positive and negative displacements and slopes depending on its relative position with respect to the face.

Jan 1, 1992

By U. Singh, E. T. Brown, J. Coxon

The rapid fracturing and deformation that occurs around excavations during rock bursts demand that support and reinforcement systems have both deformability and damping capabilities. The energy demand and supply approach currently used in design is considered to be too simplified to represent adequately the rock burst process and the support and reinforcement system requirements. Momentum change may be a necessary second criterion for the analysis of dynamic loading situations. At the St Ives Gold Mining Company, DE plates made from conveyor belt rubber, and dynamic cables with sliding anchors have been developed and used to improve the dynamic performance of support and reinforcement systems. La fracturation rapide et la déformation qui se produisent autour des excavations lors de coups de terrain demandent que les systèmes d’armature et de support soient déformables et aient une capacité d’amortissement. L’approche basée sur l’énergie actuellement utilisée pour la conception est considérée être trop simplificatrice pour représenter adéquatement les coups de terrain et les paramètres de conception des systèmes d’armature et de support requis. Le changement de quantité de mouvement pourrait être un second critère nécessaire pour l’analyse des cas de charge dynamnique. St Ives Gold Mining Company a développé et utilisé des plaques « DE » constituées de caoutchouc de courroie de convoyeur et des câbles dynamiques avec ancrage coulissant afin d’améliorer la performance dynamique des systèmes d’armature et de support. Die ploetzliche Rissbildung und Verformung, die sich in Baugruben waehrend eines Felseinbruchs ereignet, verlangt Stuetz- und Verstaerkungssysteme, welche verformbare und mildernde Eigenschaften aufweisen. Die derzeitlich gebraeuchliche Methode den Entwurf auf den Energiebedarf und dessen Abdeckung zu basieren, wird als eine unannehmbare Vereinfachung betrachtet, da sie den Felseinbruch und die benoetigten Unterstuetzungs– und Verstaerkungssysteme unzulaenglich darstellt. Die Aenderung der Umstaende kann einen zweiten Ansatz fuer die Analyse der Lastsituation erforderlich machen. Die St.Ives Gold Mining Company hat DE Platten aus Foerderband-Gummi und elastischen Kabeln mit verschiebbaren Verankerung entwickelt und dazu verwendet, die dynamische Kapazitaet der Unterstuetzungs- und Verstaerkungssysteme zu verbessern.

Jan 1, 2003

By L. W. Scott, T. H. Dubaniewicz, F. T. Duda, P. G. Kovalchik

Recent research conducted by NIOSH, Pittsburgh Research Laboratory showed that electrical current levels permitted under parent regulations may not limit cable temperatures to less than 90 °C in reeled trailing cables. Reeled cables, tightly wrapped with many turns, ell carrying current in an enclosed space, can become overheated due to poor heat transfer. This overheating can cause the cable insulation to soften and become easily damaged. The damaged insulation reduces the life of the cable and can lead to shock, electrocution, and mine foes. This paper describes a method of measuring the conductor temperature of untie trailing cables during no anal operation. The temperature is measured using a 50/175 micrometer Graded Index Multimode Optical Fiber located in the center of the metallic conductors. Distributed temperature measurements arc made using an Optical Time Domain Reflectometer (OTDR). This system is capable of measuring temperature with an accuracy of plus or minus one degree centigrade over a length of 4 km at 1-m intervals. With this unique way of measuring temperature, tests can be conducted simulating actual mine conditions and provide important data to allow MSHA's Approval and Certification Center to develop approval criteria for cyclically rated reeled machines.

By L. W. Scott, T. H. Dubaniewicz, F. T. Duda, P. G. Kovalchik

Recent research conducted by NIOSH's Pittsburgh Re¬search Laboratory showed that electrical current levels permitted under present regulations may not limit cable temperatures to less than 90°C in reeled trailing cables. Reeled cables, which are tightly wrapped with many turns and which carry current in an enclosed space, can become overheated due to poor heat transfer. This overheating can cause the cable insulation to soften, making them prone to damage. The damaged insulation reduces the life of the cable and can lead to shock, electrocution and mine fires. This paper describes a method of measuring the conductor tem¬perature of mine trailing cables during normal operation. The temperature is measured using a 50/125-, µm graded index multimode optical fiber located in the center of the metallic conductors. Distributed temperature measurements are made using an optical time domain reflectometer (OTDR). This system is capable of measuring temperatures with an accuracy of ± I °C over a length of 4 km at I -mintervals. With this unique way of measuring temperature, tests can be conducted that simulate actual mine conditions. The tests provide important data that allows MSHA's Approval and Certification Center to develop approval criteria for cycli-

Jan 1, 2000

By P. G. Kovalchik

Recent research conducted by NIOSH, Pittsburgh Research Laboratory showed that electrical current levels permitted under present regulations may not limit cable temperatures to less than 90°C in reeled trailing cables. Reeled cables, tightly wrapped with many turns, all carrying current in an enclosed space, can become overheated due to poor heat transfer. This overheating can cause the cable insulation to soften and become easily damaged. The damaged insulation reduces the life of the cable and can lead to shock, electrocution, and mine fires. This paper describes a method of measuring the conductor temperature of mine trailing cables during normal operation. The temperature is measured using a 50/125 micrometer Graded Index Multimode Optical Fiber located in the center of the metallic conductors. Distributed temperature measurements are made using an Optical Time Domain Reflectometer (OTDR). This system is capable of measuring temperature with an accuracy of plus or minus one degree centigrade over a length of 4 km at 1-m intervals. With this unique way of measuring temperature, tests can be conducted simulating actual mine conditions and provide important data to allow MSHA's Approval and Certification Center to develop approval criteria for cyclically rated reeled machines.

Jan 1, 1998

By R. Chen, K. Xia

In deep mining activities, blasting induced compressive stress wave would be reflected as tensile wave at a free surface around the openings, which would facilitate the tensile failure of the deep rock since it is much weaker in tension than in compression. It is thus critical to understand the dynamic tensile failure of rocks subjected to static tension for deep rock engineering applications. A modified split Hopkinson pressure bar (SHPB) system is adopted to load Brazilian disc (BD) samples statically, and then exert dynamic load to the sample through stress wave generated by impact. The pulse shaper technique is used to generate a slowly rising stress wave and thus to facilitate the stress equilibrium of samples during each test. Five groups of Laurentian granite (with tensile strength of 12.8 MPa) BD samples under the pretension stress of 0 MPa, 2 MPa, 4 MPa, 8 MPa, and 10 MPa are tested under different loading rates. The result shows that the dynamic tensile strength of the rock decreases with the increase of pre-tension stress, which is easy to understand because pre-tension stress weakens the rock sample. It is also observed that under the same pre-tension stress, the dynamic tensile strength increases with the loading rate, revealing the so-called rate dependency that is common for engineering materials. Furthermore, it is found that the loading rate sensitivity of the rock increases with the increase of pre-tension stress. A qualitative explanation for this phenomenon is that more microcracks are generated and activated under higher pretension stress, resulting in a more viscous material. Based on the results, an empirical equation is proposed to fit the data and explain the dynamic tensile behaviour of rock under pre-tension stress. A physical model is used to simulate the dependency of the dynamic tensile strength of rock on the pre-tension stress and the loading rate, which is shown to be in good agreement with the experimental results.

Jan 1, 2015

By Jörn M. Seitz

Dynamic load testing is employed with ever increasing frequency to estimate the strength and elastic settlement behavior of piles of all types. For dynamic loading ram masses up to 20 Mg have been used and pile resistance forces up to 30 MN have been activated. Strains and accelerations induced by the impact are measured near the pile top and a load-set curve is computed by the so-called CAPWAP method. This paper briefly describes both the necessary equipment and other details of the dynamic tests and the available analytical tools for data interpretation. Furthermore the need for further research and the current status of standardization will be discussed. This paper also presents the results from several static and dynamic correlation tests on cast-in-situ piles of up to 2 m diameter and 64 m length. The results demonstrate the economical and technical feasibility of this test method.

Jan 1, 1987

By A G. Thompson, E Villaescusa, A De Zoysa, J R Player

Ground support performance is critical to the safe and economical extraction of ore. This is particularly important for mass mining extractions at great depth, which are currently being considered by a large number of mining companies worldwide. As the in situ stresses concentrate around critical excavations, failure occurs at the excavation boundaries and ground support is required for the excavations to remain safe and accessible for their intended lifespan. Ground support consists of reinforcing elements that are installed within the rock mass to modify its internal behaviour (generally to within one excavation radius) and surface support elements that are installed at the exposed boundaries to retain the failed pieces of rock. For surface support to be effective, the loadings need to be transferred to the reinforcing elements; however, the combined performance of rock bolts and mesh is poorly understood in terms of the energy dissipation capacity available for a typical ground support scheme implemented at most mass mining operations.Over the last 15 years or so, a large number of large-scale laboratory experiments have been completed at the Western Australian School of Mines (WASM) Dynamic Test Facility for reinforcement systems and surface support systems loaded separately. The objective of more recent testing has been to establish the combined energy dissipation capacity of typical and enhanced reinforcement systems combined with mesh surface support. Total energy dissipation has been separated into energy dissipation attributable to the reinforcement and to the mesh. The results of the tests are presented and compared with the existing WASM design demand and capacity guidelines.CITATION:Villaescusa, E, De Zoysa, A, Player, J R and Thompson, A G, 2016. Dynamic testing of combined rock bolt and mesh schemes, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 789–798 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

A rough simulated borehole has been developed for the installation and dynamic testing of rock bolts a the WASM Dynamic Test Facility. The rough simulated borehole is used for rock bolts that are sensitive to equipment installation technique or borehole geometry (particularly friction rock stabilisers and resin encapsulated bolts). An extensive axial test program has quantified a difference between the static and dynamic capacity (kN/m of embedment) for friction rock stabilisers once sliding starts. The 47mm split tube bolt has a 50% reduction in embedment capacity (but with significant variation) dissipating 2.7kJ/100mm of sliding per meter of embedment, and the Omega (inflatable) bolt had a 70% reduction in embedment capacity dissipating 6.2kJ/100mm of sliding per meter of embedment. The Omega bolt dynamic capacity remainder at least equivalent to the split tube bolt static capacity.

May 1, 2009

By P. Srinivasulu

The popular theoretical models used for assessing the dynamic behaviour of piles under vertical and lateral excitations are critically reviewed. An experimental study is presented on model piles with varying slenderness ratios. The theoretically evaluated and experimentally deduced natural frequencies and resonant amplitudes of the test pile-soil system are compared. The dynamic stiffness and damping are seen to increase with increasing slenderness of piles. Further, the damping yielded by the theory is found to be on the unconservative side.

Jan 1, 1996

A comprehensive axial test program has been undertaken at the WASM Dynamic Test Facility on the performance of 20mm threadbar. The threadbar tests had a double embedment configuration, with variation to the encapsulation lengths, debonded length and surface hardware and fixtures to examine failure mechanisms. Performance was significantly affected by the collar embedment length and type of fixture nut used. Results ranged from thread shearing occurring between the nut and bar at 1kJ of energy dissipated, to control plastic deformation of a central debonded length dissipating 22kJ.

May 1, 2009

By D. Michael Holloway

The California Department of Transportation (CALTRANS) evaluated several pile foundation schemes for supporting the structures along the realignment of Interstate 880. The project replaces the double-decked (Cypress) viaduct collapsed in Oakland, California during the 1989 Loma Prieta Earthquake. Structural support demands led to the selection of steel pipe piles (16-, 24-, and 42-inch-(406-, 610- and 1067-mm-)diameter), filled with concrete and steel reinforcement. Deep penetrations required through layers of very dense/cemented sands in some locations, caused serious drivability and pile integrity concerns. The need for large pile driving hammers and large diameter steel pipe piles pushed the engineers well beyond local experience. Such questions as the feasibility of driving the pipes closed-ended through dense upper strata and quantifying the effects of installation on the long-term capacities of the piles led Caltrans to develop a comprehensive pile test program to address the design and construction issues effectively. The results were furnished to prospective bidders on the production stages of the ensuing contracts.

Jan 1, 1995

By C. C. Li

The D bolt is a new type of energy-absorbing rock support element recently developed in Nor-way. The D bolt is not only able to accommodate large rock deformations, but can also provide a load-bearing capacity as high as that of rebar bolts. Furthermore, the anchoring quality of the D bolt is similar to rebar bolts because of its multi-point anchoring design.

May 1, 2009

By Sun Ying, Zhang Jing, Li Qiuju

A new process of enrichment Cu in molten copper slag under electric field is presented in this article. The experiments were carried out in the laboratory on a kilogram scale. The mobility of copper slag was improved by the technique of carbon reduction. The effects of temperature, electric field strength and intermittent feeding speed were investigated on Cu migration. The results showed that the best experimental conditions were the temperature at 1523K, electric field strength was 1.5V•cm-1 and feeding rates was 15 g•(10min)-1. The copper content of the slag decreased below 0.6wt%. The process was compared to the traditional electric furnace process of slag cleaning, there was reduced the energy consumption and heat loss, and also harmful gas emissions such as SO2 and CO2, accompanied by improved the efficiency of slag cleaning.

Jan 1, 2016

By Samuel Filgueiras Rodrigues, Clodualdo Aranas Jr., Gedeon Silva Reis, Eden Santos Silva, Fulvio Siciliano

When austenite is deformed above the Ae3 temperature, partial amount of it transforms dynamically into ferrite by a displacive mechanism. After unloading, it retransforms back into the stable austenite by a diffusional process. This influences the rolling load which decreases under isothermal condition or does not increase with decreasing temperature as rapidly as expected under cooling. Plate rolling simulations under isothermal and continuous cooling conditions were carried out on a 0.09 wt.% Nb X-70 steel. Pass strains of 0.2 were employed together with interpass times of 10 s, and 30 s for the cooling conditions and 0.3 with interval of 10 s at 900 °C for the isothermal experiments; strain rate of 1 s-1 was used during the simulations. The mean-flow-stress (MFS`s) behavior of both conditions indicates that dynamic transformation and dynamic recrystallization were taking place during straining. The critical strains for the initiation of dynamic transformation fell around 0.06 while the critical strain for DRX was 0.12. It has been shown that ferrite is formed due to the applied deformation of roughing passes and increases its volume fraction throughout the finishing rolling stage. Under cooling conditions, the ferrite formation is also favored as the temperature approaches the Ae3 line. Such ferrite forms when the driving force for dynamic transformation is higher than the total free energy barrier preventing its formation. This obstacle consists of the free energy difference between austenite and ferrite as well as the lattice dilatation work and shear accommodation work. The addition of Nb retards the retransformation of the ferrite into austenite. Moreover, holding times after rolling increases the amount of austenite available for microstructure control on subsequent stages. The dynamic transformation (DT) mechanism can be used to design improved rolling schedules

Oct 1, 2019

By Messenger A. J, Miles J. G

A thermal neutron irradiation technique using a mCf neutron source has been developed and applied to thp.simultaneous determination of iron and aluminium (expressed as AI2O3) in iron ore fines (-6 mm particle size) on a moving rubber conveyor belt.While the determination of iron with this technique is based on the use of a NaI(TI) detector to monitor the characteristic prompt gamma rays (7.64 MeV) emitted by thermal neutron capture reactions in the iron, the etermination of AI2O3 is based on the use of a second Nal(Tl) detector to monitor the characteristic gamma rays (1.78 MeV) emitted after thermal neutron activation of the aluminium. The second detector is located downstream from the first. Although the speed of the conveyor belt has no direct effect on the iron measurements, it must not exceed about 3 m/min if good accuracy is required for the AI2O3 measurements. Consequently an auxiliary conveyor belt is required in order to avoid interference with normal ore processing.Dynamic trials of the technique, using 1500 kg samples of ore on a 460 mm-wide rubber conveyor belt moving at 1.7 m/min, have demonstrated that the method can achieve accuracies of 0.7% Fe and 0.1% AI2O3. At the present stage of development, it is recommended that lump ore be crushed to a particle size of 6 mm before analysis.In addition to iron and AI2O3 determinations, measurements of total moisture content and bulk density are possible. The determination of Si02 is also feasible, but a separate fast neutron source (e.g., Am-Be) and a separate gamma ray detector are required.

Jan 1, 1980

By Justin Cardwell, Alyson Cartwright

"Grade estimation is the cornerstone of longrange mine planning. Pit designs, metal recovery, mining costs, reserves calculations and reporting are all dependent upon a reliable grade model. If the geology is poorly understood or the interpolation methods and parameters have been haphazardly constructed, then massive financial losses will be the inevitable outcome. Therefore, a properly trained geologist must use all of the appropriate tools available including deposit knowledge and advances in modeling technology to construct the most geostatistically and practically sound long-range block model.Certain deposits, such as the sedimenthosted deposits at Tenke-Fungurume, require an interpolation method that best suits the style of mineralization. In 2014, Hexagon Mining developed a tool in MineSight called dynamic unfolding (MSDU) that has the potential to improve upon previous Euclidean-based interpolation methods. MSDU utilizes the nonstationarity of a folded grade trend to more accurately construct variograms and improve interpolation results based upon a modeled three-dimensional surface.Geology overview. The sediment-hosted Tenke-Fungurume mining district is located in the southeastern part of the Democratic Republic of the Congo (Fig. 1). The rocks within the district are primarily dolomites and shales from the lower half of the Roan Supergroup that were mineralized by ascending pregnant copper and cobalt rich brines within a massive sedimentary basin (Cailteux et al., 2005) (Fig. 2). These oxidized brines likely found a fluid channel in the porous RSC unit. The surrounding rock units provided a redox boundary for copper and cobalt precipitation along organic rich beds, forming a massive stratabound deposit that was later broken up by several subsequent tectonic events (Dewaele et al., 2006)."

Jan 1, 2015

By A. Cartwright, J. Cardwell

"Complex geology requires innovative approaches to confidently and appropriately model grade and geologic trends. Local Anisotropy Kriging (LAK), by Isaaks and Company, and MineSight® Dynamic Unfolding (MSDU) from Hexagon Mining are advanced interpolation methods designed to best estimate grade along deformed three-dimensional grade trends at sediment-hosted deposits. While LAK works in Euclidean space for the construction of variograms, kriging weight assignment, and non-linear local interpolation search ellipsoids, MSDU is far more dynamic and can utilize a modeled three-dimensional undulating surface representing a folded grade trend to construct the above mentioned. MSDU was implemented at the sediment-hosted, stratabound Tenke-Fungurume mining district and revealed major block-to-block differences in interpolated copper and cobalt grades compared to LAK. INTRODUCTION Grade estimation is the cornerstone of long-range mine planning. Pit designs, metal recovery, mining costs, reserves calculations and reporting are all dependent upon a reliable grade model. If the geology is poorly understood or the interpolation methods and parameters have been haphazardly constructed, then massive financial losses will be the inevitable outcome. Therefore, a properly trained geologist must use all of the appropriate tools available including deposit knowledge and advances in modeling technology to construct the most geostatistically and practically sound long-range block model. Certain deposits, such as the sediment-hosted deposits at Tenke-Fungurume, require an interpolation method that best suites the style of mineralization. In 2014, Hexagon Mining developed a tool in MineSight called dynamic unfolding (MSDU) that has the potential to improve upon previous Euclidean-based interpolation methods. MSDU utilizes the non-stationarity of a folded grade trend to more accurately construct variograms and improve interpolation results based upon a modeled three-dimensional surface. Geology Overview The sediment-hosted Tenke-Fungurume mining district is located in the southeastern part of the Democratic Republic of the Congo (Figure 1). The rocks within the district are primarily dolomites and shales from the lower half of the Roan Supergroup that were mineralized by ascending pregnant copper and cobalt rich brines within a massive sedimentary basin (Cailteux et al., 2005) (Figure 2). These oxidized brines likely found a fluid channel in the porous RSC unit. The surrounding rock units provided a redox boundary for copper and cobalt precipitation along organic rich beds, forming a massive stratabound deposit that was later broken up by several subsequent tectonic events (Dewaele et al., 2006). Layering and Block Orientations To capture the bedding-controlled nature of the Tenke-Fungurume copper and cobalt mineralization, each lithology type must be subdivided into individual layers with a uniform thickness (Figure 3). The thickness of each layer is determined by the user, but should equal the bench height to achieve maximum resolution within each lithology type. Composites are back coded from the model to achieve layer codes that match block locations."

Jan 1, 2016

By Ingvar Ymén, Anders Sandc, Jan Rosenkranzc, Lisa Malma, Ann-Sofi Kindstedt Danielssonb

The understanding of particle surface properties is essential for the study and evaluation of froth flotation phenomena, particularly in the investigation of various chemical or reagent effects. Dynamic Vapor Sorption (DVS) is a method used for the analysis of surface properties of powders for instance in the pharmaceutical industry. To the knowledge of the authors, it has however not been used before in applications related to mineral processing. The DVS technique involves measurement of the water uptake of a relatively small amount of sample as a function of the relative humidity (% RH) in a temperature-controlled environment. The purpose of this work was to evaluate the method and investigate how it can complement existing techniques for surface characterization in mineral processing. Four samples (feed, CuPb concentrate, Cu concentrate and Pb concentrate) from the Cu – Pb flotation process in the Garpenberg concentrator, Sweden, were analyzed by DVS and the traditional capillary absorption technique (Washburn capillary rise). This enabled comparison between the two methods and evaluation of their respective advantages and disadvantages. Both methods give the expected ranking of the hydrophobicity for CuPb concentrate, Cu concentrate and Pb concentrate, but a discrepancy was observed for the feed. Washburn gave a value for the contact angle which was in the same range as for the CuPb concentrate, whereas DVS gave a value for the moisture uptake which was much higher than for the CuPb concentrate. Thus, DVS ranks all samples correctly, but with an unexpectedly high value for the feed whereas Washburn gives good ranking for three samples out of four. Potential reasons for the discrepancies are discussed.

Jan 1, 2018

By D. -A Tremblay

Dynamic wetting spread factors and interfacial heat transfer coefficients were determined for aluminum droplets solidifying on copper substrates, The spread factors were determined from the droplet geometries while the heat transfer coefficients were obtained by solving inverse heat conduction problems, 1-D and 2-D heat transfer models are presented and the results they provided are compared, For the latter, a sensitivity analysis was also performed to determine the influence of thermophysical properties and boundary conditions. Experiments were alternatively carried out with three different gaseous atmospheres and the dynamic wetting spread factors were correlated to the interfacial heat transfer coefficients.

Jan 1, 2005