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By T. A. Wedge

This paper suggests a crude correction for the impact of raw material quality on factor productivity in the Canadian mining industry. Such a correction would give a figure more dependent on the changing efficiency of the use of labour and capital, and less dependent on the effects of unquantified changes in inputs.

Jan 1, 1973

By Kristine Haug

Although most in situ operations in Alberta do not encounter significant problems during resource extraction, there have been a few documented occurrences of oil or steam releases as a result of compromised caprock seals. The objective of the Oil Sands Caprock Integrity Project (OSCRIP) is to characterize the units above and below bitumen zones to determine which geological factors affect the quality of the caprock seal. In addition, geomechanical properties and stress measurements of the bitumen reservoir and overlying units will be examined to provide a better picture of the containment conditions in which in situ operations occur. The information from this study will aid regulatory staff and industry in determining the zone-specific geological and geomechanical factors that could affect the design, operation, and feasibility of in situ recovery projects. The OSCRIP study area (Townships 87 to 99 and Ranges 1 to 13, West 4th Meridian) encompasses the surface mineable area, the northeast extent of the Wabiskaw-McMurray bitumen deposit and the Clearwater Formation, as well as a wide band of the Devonian salt-dissolution zone. Regional geological mapping of the Cretaceous strata focuses on the spatial extent and thickness of the caprock seal. Mapping of the underlying Devonian strata is targeted at better understanding the potential effects of salt dissolution and collapse of overlying strata on the integrity of the caprock seal. Examination of LiDAR (Light Detection And Ranging) bare earth DEM in the study area has revealed localized depressions that may represent sinkholes rooted in subsurface collapse features in Devonian carbonate and evaporite strata. Mapping the location and understanding the timing of salt dissolution-related features and deformation in the Devonian strata will help address questions about the possible effect that geological structures, such as sinkholes, have on the integrity of the caprock, as well as the potential for localized variations in the stress regime of the bitumen zone and overlying units. The stress regime in units above 350 m is such that any induced fractures are believed to be horizontal, and therefore, there would appear to be no mechanisms that would allow these fractures to reach the surface. However, recent incidents have shown that vertical pathways can occur, linking the subsurface to the surface. The final phase of the project will evaluate the changes that may occur in the stress regime under thermal operating conditions in the study area.

Jun 1, 2012

By Dan Miners

"This presentation will provide an overview and understanding of Mine Safety and Health Administration (MSHA) and Ontario Regulations for Mines and Mining Plants. It includes discussions on the history and practical development of the standards and an overview of engineering best practices from a construction, maintenance and operational viewpoint. INTRODUCTION Ontario is one of the safest mining jurisdictions in the world and has some of the most comprehensive regulations for the construction, operation and maintenance of a mine. In the USA, several operators have adopted some or all of the practices prescribed by the Ontario Regulations as an internal procedure. Experience has demonstrated that these plants are indicating less unplanned downtime and fewer issues with MSHA inspectors in their hoist plants. HISTORY AND THE REGULATIONS Both Canada and the USA have had some form of laws governing the operation of mines since the late 1890s. The paths of legislation have run in reasonably parallel lines, continually improving the health and safety conditions in the mining industry. Ontario Mine Health and Safety In the 1970s the accident rates in mining were higher than any other industrial sector; this prompted a Royal Commission on the Health and Safety of Workers in Mines (the Ham Report). The recommendations of this report, published in 1976, generated several changes in the regulations regarding worker safety in mines. Following the release of the Ham report, the Occupational Health and Safety Act (OHS) was passed by the Legislature in 1978. The Act is a set of comprehensive laws governing almost all Ontario workplaces, and it replaced separate laws governing different industrial sectors. OHS is enforced by the Ministry of Labour (MOL), and this discussion will focus specifically on Ontario’s Occupational Health and Safety Act, R.R.O. 1990, Regulation 854, Mines and Mining Plants, Part X Mine Hoisting Plant (Ontario Regulations). USA Mine Health and Safety A coal mine explosion in West Virginia and medical studies on occupational disease led to the 1969 Federal Coal Mine Health and Safety Act (Coal Act). The Coal Act was the most comprehensive and stringent Federal legislation governing the mining industry to date. The Mining Enforcement and Safety Administration (MESA) was formed, following the 1973 Act, as a new departmental agency to assume the enforcement of safety and health in mines. The Federal Mine Safety and Health Act of 1977 (Mine Act) transferred enforcement responsibilities from the Department of the Interior to the Department of Labor and named the new agency the Mine Safety and Health Administration (MSHA). This agency enforces the Code of Federal Regulations (CFR), and this discussion refers to CFR Title 30 Mineral Resources, Chapter I Mine Safety and Health Administration, Department of Labor, Subchapter K—Metal and Non-metal Mine Safety and Health (MSHA)."

Jan 1, 2019

"A numerical procedure based on Smoothed Particle Hydrodynamics (SPH) is developed for rock blasting phenomena involving multiple intersecting joints. In this procedure, an elasto-plastic damage constitutive model has been applied in the framework of SPH to simulate yielding response of the surrounding rock medium. In this paper, a square shape rock medium with centrally located emulsion explosive in a borehole is numerically blasted with and without the presence of two diagonal rock joints. The model is simulated by assuming all four sides of the rock medium as free surfaces. The paper elaborates the propagation of stress wave, expansion dynamics of gaseous products, and development of fracture, fragmentation of the medium and dissipation of energy due to damage.INTRODUCTIONDamage prediction of rock mass and its mean fragmentation size are of important to design blast parameters for a given explosive. Current blasting practice solely depends on empirical relationships between fragmentation sizes to those blast design parameters while mathematical descriptions of the physical laws governing the process of rock blasting are limited. A constitutive relationship based on properties of explosives and rock mass is of special interest because of its capabilities in describing the key features of rock fracture and fragmentation, resulting in understanding of the physical process involved in rock blasting. It is well known that blast-induced damage and fragmentation of rock mass occur due to detonation induced stress wave and product gas driven fracture propagation. Nevertheless, the fundamental mechanism of the failure process and the behavior of rock characteristics under these two different loading are not well understood in many cases, which are closely related to growth of fractures and interaction of cracks under different loading conditions.Continuum damage mechanics is considered to be appropriate to describe the failure process under such high-amplitude stress wave. Based on this approach, several theoretical models have been developed to analyze the dynamic damage of brittle material such as rock and concrete with microstructure (Chen, 1999; Taylor et al., 1986; Wu et al., 2004; Yazdchi et al., 1996). These models are mostly based on the theory of damage mechanics or fracture mechanics with some statistical treatment to incorporate random distribution of microcracks. In the application of fracture mechanics theory, sometimes it is difficult to estimate the micromechanical parameters such as crack density and fracture toughness in different modes. In this study, damage in rock material is evaluated according to the earlier model developed by Grady and Kipp (1980), which is a fracture model coupled with a material description for stress wave propagation to predict quantitatively fracture and fragmentation under explosive loading conditions."

Jan 1, 2015

By J. G. Kim, B. G. Chae, D. S. Cheon, E. S. Park

The underground structures such as high-level radioactive waste disposal thermal energy storage should be designed and constructed considering thermal-mechanical characterization because of long term and/or cyclic thermal stress. High temperature changes in these structures can extend the existing cracks and generate new cracks in surrounding rock mass. In case of long term and/or cyclic thermal stress conditions, it is possible to lose the function of structures caused by the significant cracks and fracture growth in the rock mass. In this study, the critical thermal crack temperature of the granite, limestone and thermal Kaiser effect were evaluated. Experiments were carried out with the heating speed of 1.5?/min. To avoid thermal shock and target temperatures were set at 150? and 250?. In order to verify the thermal Kaiser effect, the samples were heated by 150 ? after 2-3 repetition to 250?. The generation and growth of cracks were observed through an acoustic emission measuring system. The variation of the physical rock properties was measured before and after thermal experiments. After compared with the thermal experiments using PFC2D, numerical simulations were carried out at higher temperatures (400?). The experiments showed that the initial thermal crack temperature of granite and limestone is about 35?, 32? and the critical thermal crack temperature were about 69? , and 49? , respectively. The experiments confirmed the thermal Kaiser effect of experimented granite and limestone due to thermal cyclic loading. From the numerical analysis, the critical crack temperature showed the same tendency as the thermal experiments. The P and S wave velocity of the sample after the experiment were reduced. Therefore, when heat is applied in long-term and repetitive conditions, these cracks may affect the function and stability of the underground structure. Therefore, further studies of thermal stress effects should be performed.

Jan 1, 2015

By L. Zeng, Q. Feng, Z. Qiu, L. Ou, Central South University

It is well-known that the use of nanobubbles can significantly improve the flotation efficiency of ultra-fine particles. However, this is mainly focused on coal and phosphate rock flotation. In the field of nonferrous metal processing, the related research is few. In this paper, a small laboratory mechanical cell associated with a specially-designed nanobubbles generator was used to investigate the effects of nanobubbles on enhancing ultra-fine scheelite flotation. Nanobubbles were created and based on the hydrodynamic cavitation principle through Venturi tubes. Comparative flotation tests were performed using different tubes to evaluate the nanobubbles impact on the ultra-fine scheelite particle flotation recovery. In order to better understand the nanobubbles enhanced ultra-fine scheelite flotation, nanobubbles potential and size distribution were measured. The effect of nanobubbles on the particle aggregation and scheelite particles potential were also studied through the turbidity tests, microscope tests and zeta potential measurements. According to the results, the mean size of nanobubbles was about several hundred nanometers, and the surface of nanobubbles was of highly negative charge in alkaline conditions. The flotation recovery of ultra-fine scheelite particles was increased in the presence of nanobubbles. The zeta potential measurements indicated that the repulsive forces between scheelite particles decreased when nanobubbles existed. Through the turbidity tests and microscope tests, the promotion effect of nanobubbles on particle coagulation could be verified more directly. The existence of nanobubbles in flotation system promotes the particle aggregation, thus increasing particles apparent size and particles capture by bubbles, which may be the fundamental reason why nanobubbles enhance ultra-fine scheelite flotation.

Jan 1, 2016

By Wm. F. Wuest

INTRODUCTION THE Western Canada sedimentary basin has one feature in common with the Precambrian Shield area: it also was a great chemical laboratory. The mining industry of Canada exploits the end products of chemical experiments that occurred on the Shield during periods of repeated disturbances in Precambrian times. The petroleum industry on the other band exploits what also appears to be the final results of chemical experiments that took place throughout all of post-Precambrian up to Tertiary times. Since the subject of this paper is a factual study of Alberta well waters, no attempt is made to answer significant questions pertaining to the probable role waters play in the generation of oil, or to the significance of the effects of structure and depth on waters. Data from several hundred well-water analyses were compiled by the writer in a series of charts and diagrams, of which those included in this paper are representative. Early studies indicated the possibility that outstanding anomalies in general concentration of waters and in greatly increased concentration of elements such as calcium, magnesium, bromine, and iodine for example, might be expected from wells that produced oil or were in the immediate vicinity of producers. The water analyses from wells which? were drilled at a later date did not confirm this possibility, and it is suggested that, aside from their initial value to the petroleum engineer or to. those interested in the commercial possibilities of brines, no definite significance as an aid in oil discovery can be attributed to water analyses.

Jan 1, 1951

By M. Hozayen, Q. Ni, E. S. Radwan, P. Nawrocki, A. Jebbouri

"A major geomechanical study was conducted for one of the UAE onshore oil fields with the purpose of studying reservoir rock properties and stress distribution, based on which a 3D coupled reservoir geomechanical model was built. This model was later used for wellbore stability analysis and for analyzing the effect of fractures on future reservoir production performance, including fracture deformation and permeability evolution occurring due to reservoir depletion and resulting changes in local stress field. The subject of this study was a complex fractured Upper Cretaceous carbonate reservoir characterized by high degree of heterogeneity, both vertically and laterally. Wellbore instability related drilling problems were encountered while drilling the wells in this field. The problems were mainly in drilling the horizontal wells, including breakouts and mud losses. Experimental results of laboratory tests used in this study are summarized in Part I of this paper whereas wellbore stability analysis and formulation of a3D geomechanical model that was built for that purpose is summarized herein.A 3D geomechanical reservoir model was developed, which included natural fractures. The mechanical properties of the reservoir rock, such as Young’s modulus, Poisson’s ratio, UCS, friction angle and tensile strength were populated based on the correlations established in Part I of this paper and the developed model was then used to simulate the 3D mechanical-property distribution and the evolution of the in situ stresses in the field due to depletion from 1983 to present-day. Based on the full field model, mud weight cubes were developed to predict the safe mud weight windows in different drilling directions. In addition, well stability prediction for two planned wells was performed using a 3D near-borehole model. Firstly, the computed stress state and mechanical properties simulated in the full field model were extracted along the well trajectory of an existing horizontal well which was drilled recently and then, a3D near-borehole model was constructed along the well trajectory. The wellbore stability analysis along the well trajectory, including stress state, strain distribution and displacements, was performed to identify the instability events along the well trajectory. It has been seen that the presence of natural fractures is closely related to the recorded borehole instability incidents. The computed plastic strains which indicate the wellbore failure were consistent with the recorded wellbore instability events in the FMI image logs, what provide further verification of the developed model. Then, this 3D near-borehole model was applied to two planned horizontal wells and the wellbore stability analysis for the two wells was carried out.The results showed that drilling vertically in the reservoir is safer than drilling horizontally. However, the drilling mud weight window in the vertical direction is narrow, being as narrow as 18.7 pcf or 0.299 sg locally. Drilling horizontally is less stable towards the maximum far field stress direction than towards the minimum far field stress direction. The mud weight cubes were used to identify the optimal well placement and well trajectory. For planned well trajectories, this technology can also be used to determine the optimal mud weight."

Jan 1, 2015

By V. Estrada, G. Aguilera

"Since the most of mineral processing are wet, and for more specific applications where it is necessary to increase the purity through leaching and / or concentration, the proper dispersion is the first, and perhaps more crucial stage in the whole chain of processing. This specific process is based on the formation of a dispersion or suspension of mineral, trying to make the mixture as homogeneous as possible, and with specific rheological conditions. Sometimes it is not enough agitation to make it happen, so that chemical additives are used as an aid. However, the addition of chemicals strongly alters the viscosity and other rheological properties of the suspension factor to consider for subsequent steps to ore beneficiation. In other hand, in a process where no chemicals used often employ large quantities of water to achieve dispersion. But if an efficient chemical agent, which optimizes said dispersion through a specific physicochemical effect on the particle surface is used, also it can generate rheological advantages, besides achieving rational use of water and increase the recoveries of the product main about also optimal costs. The aim of this work is to find the optimal rheological conditions for a dispersion of kaolin as study case, looking for stability, best disaggregation, viscosity and pseudoplasticity.To find the optimal additive, the evaluation parameters were: 1) Best degree of dispersion of the suspensions according to the analysis of the flow curve; 2) Best level of disaggregation of particle chemical analysis delaminated by Particle Size Distribution; and 3) Best thixotropic rheological parameters and pseudoplasticity. Finally the optimum additive as one that meets the best combination of parameters is proposed.INTRODUCTIONKaolin is a clay material formed by altering of feldspar composed mainly for kaolinite. Depending on the application, the kaolin as raw material must be refined and processed because the ores of clays contain usually a lot of impurities derived of its sedimentary source, such as feldspar, mica and quartz (Torres, et. al., 2011). According to the experience on the plant floor and the publication of several scientific papers, it is known that the dispersion is a crucial stage in mineral processing (Greene, Duke, & Hunter, 1965) (Raghavan, et. al., 2004), not only because of the disaggregation of particles, besides because of the humectation of them. Is clear that disaggregation of particles give to the suspensions rheological stability, and the humectation improves the effect of further processes like grinding or chemical treatment. The dispersion process involves making a suspension of the mineral with a solvent which is usually water, to obtain a homogeneous dispersion, with the aid of energy of stirring. Sometimes is not enough the agitation (even with high energy) for this to occur, so is necessary the use of dispersing substances which introduce ions and molecules as modifiers of chemical potential, forcing the molecules of the material to disperse. Sometimes their use even could affect the pH of the suspension in a non-desirable condition. (Flores, 2013)."

Jan 1, 2016

By P. Wanjara, M. Xiao

During fusion welding of aluminium alloys, the avoidance of defects (such as porosity, oxides, hot cracking, undercutting) as well as the ability to optimize the microstructure-property characteristics in the assembly are critical for the stringent manufacturing specifications in the aerospace industry. In this work, aluminium alloy (AA) 2024 was electron beam welded autogenously as part of a study to determine the influence of parametric conditions on the characteristics of the heat affected and fusion zones to obtain optimal welding conditions. In particular the evolution in the weld geometry, microstructure and mechanical properties were examined as function of the processing conditions, including beam current, beam focus, beam oscillation, linear heat input and welding speed. For optimized parametric conditions, microstructural examination of the joints revealed narrow fusion and heat-affected zones comprising of dendritic structures without the occurrence of defects that enabled a maximized joint efficiency.

Jan 1, 2006

By P. Ramirez

"To achieve an optimal metallurgical performance in the flotation process the bubble diameter should be between 0.5 and 2.5 mm. To control bubble size, frothers are added, reducing bubble size and conferring bubble stability against coalescence. However, the bubble generation mechanism determines predominantly the bubble size distribution produced. In mechanical flotation cells, bubbles are produced by the shear stress generated by a rotating blade on a gas stream. This mechanism produces a log normal bubble size distribution. In contrast, in column flotation, jetting gas injectors are commonly used in Chile and the bubble size distribution is bimodal with small and large bubbles. Bubbles larger than 2.5 mm mean a loss in surface area, while bubbles smaller than 0.5 mm move with the pulp stream and therefore collide less frequently with particles. In this paper, a new device based on a jetting sparger and a deflector disc (impinging jetting) is evaluated as an alternative sparger for column flotation.The new device was tested in a rectangular acrylic cell 1 m × 0.5 m × 3 m. High-speed cinematography was used to compare bubble generation with jetting and impinging jetting at different gas velocity in the nozzle (5–50 m/s). From the image analysis, it was observed that the deflector induces a shear stress, in analogy to a rotating blade but in this case the shear results from a high velocity gas hitting a static surface. The device was evaluated in a 0.5 m diameter 3 m high column. The McGill bubble viewer technique was used to compare the bubble size generated by jetting and impinging jetting. It was found that the Sauter mean bubble diameter reduced from 7.4 mm to 2.8 mm, when the jetting sparger was modified with the deflector. In the case of the impinging jetting sparger, 70% of the bubbles were in the effective range for flotation, while for the jetting sparger, only 10% were in the effective range."

Jan 1, 2016

By T L. Horsley

The change from a seasonal to a continuous mining operation at Cassiar has been accompanied by increased emphasis on the preventive maintenance of mining equipment. This paper describes how equipment maintenance is organized, and details some maintenance practices that have proved advantageous to the Cassier operation. Introduction Cassiar Asbestos Corporation Limited is currenly carrying out an open-pit mining operation at the 6,300-foot elevation on McDame mountain in northern B. C. A 6-mile road connects the mine to the mill and plantsite at the 3,500-foot elevation. Ore concentrate is delivered to the mill via a 3llz-mile tramline. Naturally level ground does not exist in the mine area. The weather is typical of mountainous regions, exhibiting wide and rapid variations in temperature. It is generally wet and windy at the mine elevation, and a heavy snowfall is common. The rock types vary from a soft, sheared serpentine to massive serpentine, to medium-hard, friable sediments to hard, blocky volcanic flows.

Jan 1, 1964

By J. W. Stickney

"On July 1, 1977 Hudson Bay Mining and Smelting Company Limited announced the commencement of construction of a 3800 ton per day concentrator at Snow Lake, Manitoba. Snow Lake, a community of 2200 people, is located 130 road miles from the main metallurgical plants at Flin Flon.The design, detailed engineering and equipment selection for the project was awarded to Wright Engineers Limited of Vancouver, B.C., who would be working in close liason with Hudson Bay Mining personnel throughout the project.The feasibility of constructing a metallurgical plant in the Snow Lake area, in addition to the concentrator at Flin Flon, had been under study since 1964 with plants of varying capacities and designs being considered. Each successive study recommended a plant of increased capacity and sophistication and finally upon an in-depth study in 1976 of ore reserves, freight rates and operational benefits, the construction of a 3800 ton per day copper-lead-zinc concentrator appeared highly benificial."

Jan 1, 1981

By L. Long

Stirred milling of nickel laterites offers possibilities for improving liberation and selective size reduction of soft nickel-bearing minerals in laterites. Batch grinding tests were performed in a Netzsch LME4 stirred mill on siliceous goethitic (SG), goethitic (G), and saprolitic (SAP) nickel laterite samples (- 2000 ?m particle size) to evaluate the effect of stirrer speed, solid content, water salinity and grinding time. A fine mineral product (-38 µm) was used to evaluate the effect of selective grinding and Ni upgrade. The optimum grinding time for the highest Ni upgrade was 0.25 min, 0.1 min and 0.1 min for the SG, G, and SAP nickel laterite, respectively. A new feed (38-2000 µm) for each nickel laterite sample was prepared for batch grinding tests under the optimum grinding conditions. Upon grinding the 38-2000 µm feed, the - 38 µm product confirmed the effect of selective grinding and nickel upgrade. Size classification followed by stirred milling is a suggested process for Ni upgrade. The best Ni upgrade result was achieved on the SG nickel laterite among the three samples. The Ni grade increased from 0.85% to 1.37%, with 27.8% Ni recovery. Bottle roll leach tests showed that for SG and SAP samples selective grinding had no dramatic effect on Ni extraction due to the slow leach rate of hard mineral particles. Stirred milling of G sample increased the surface area of goethite, resulting in higher Ni extraction. Gravity concentration through a Knelson Concentrator was not effective in the further treatment of the stirred milling products either due to the poor operating conditions or due to the mineralogy characteristics of the feed samples. The energy requirement in the stirred milling was investigated. The first pass of the signature plots study is critical for the purpose of selective grinding, because the best result on selective grinding is achieved in the early stage of the grinding process.

Aug 1, 2013

By Chris D. Veldhoen

If you ask most diamond drillers if they have ever encountered methane gas, the answer would probably be yes. This paper explores a serious methane gas explosion that the author experienced while diamond drilling at a northerly Ontario mine. It is hoped that by documenting this event, people may be alerted to the hidden danger posed by confined methane in underground workings. Methane gas tends to be a problem the deeper you get in any Canadian gold mine. Common procedure when encountering methane is to take readings at the collar of the hole and at different lengths from the source. Monitoring continues until the readings drop below 0.25 ppm. Methane is a tasteless odorless gas that is usually locked up in the seams of the rock or is a product of decaying organic material. Occasionally, the gas is released abruptly over a short period of time. Sometimes the gas can continue to vent for months or even years. In small concentrations, methane is relatively safe. In concentrations under 0.25 ppm methane gas is considered safe to work around. Concentrations over 0.25 ppm can become dangerous. During the summer of 2001, Chris Veldhoen was drilling at a gold mine in Ontario. There were three electric hydraulic diamond drills on the 39 meter level, approximately 5200 feet deep. Two Longyear LM 55 drills were about 40 feet apart and another LM 75 was about 2000 feet away. The two LM 55?s were set up to drill holes no deeper than 350 meters. All three drills had been set up on the same spot for more than a month. None of the three drills had ever encountered methane gas in the entire time they had been drilling on the level. On the day shift of July 13 2001, the driller on Chris? cross shift hit a small pocket of gas. He tested the hole and got a reading above 0.25 ppm. He proceeded to rope off the area with a ?DO NOT ENTER - METHANE GAS? sign and a rope denying access beyond the sign. On Saturday, July 14, Chris was instructed to install a Margo plug in the hole that was emitting methane gas. Methane is usually odorless, but occasionally when encountered underground, is accompanied by a rotten egg smell. As he walked to the drill, he could not smell methane gas. He proceeded to test the hole and got a reading of 0.22 ppm methane. This number was in the acceptable range for drilling, but he plugged the hole anyway.

May 1, 2004

By J. A. Orr

The details connected with the mining and subsequent handling of Creighton ore were fully covered in a paper presented to the Institute in 1920. The following brief notes describe certain phases of the present practice and show wherein it differs from the practice at that time. These may be summarized under the following headings. (a) Recovery of pillars. (b) Drawing the ore. (c) Change from sub-level tramming to branch-raise system. (d) Chute construction. The present stoping practice is the same as formerly, i.e., fiat-backed shrinkage stopes of 60-foot width, between rib pillars of 15-foot width, extending from the footwall to the hanging-wall. Formerly, when these stopes were completed to the stopes above, they were drawn empty of broken ore, and the 15-foot rib pillars were caved into the stopes and drawn off through the same chutes as were used to draw the ore from the stopes.

Jan 1, 1926

By G. Kordosky

The experience of one plant regarding degradation of copper solvent extraction reagents in the presence of 20 to 30 g/1 nitrate in the leach solution was described at Cobre 2003. However, little information is available about the degradation of copper solvent extraction reagents where the nitrate concentration of leach solution is much lower. Analysis of plant organic samples taken from an operating copper SX plant over a long period of time shows that small amounts of nitrate in the leach liquor can be a significant contributor to reagent degradation provided certain other conditions are present. These conditions are discussed and cautionary suggestions on copper SX plant operations in the presence of even low levels of nitrate in the pregnant leach are made based on industry experience with copper solvent extraction plants and copper solvent extraction reagents.

Jan 1, 2007

By F. Shi

The JKRBT (JK Rotary Breakage Tester) is a newly developed impact breakage testing device for rapid ore breakage characterisation, and has recently been commercialised after a three year comprehensive validation study, involving five major mining companies and six industrialised JKRBT units deployed worldwide. Comparisons of breakage mechanisms and characterisation data between the JKRBT and the Drop Weight Tester (DWT) indicate that, despite the differences in the breakage modes, the JKRBT can provide statistically similar A*b parameters, by using a data reduction procedure which takes into account the difference in the number of contact points, strain rate and potential for secondary breakage. Feedback from the validation sponsors has indicated higher productivity and better repeatability of the JKRBT compared with the DWT. This better precision, combined with the JKRBT’s wider particle size capability and wider specific energy range, provide a more powerful tool, ideally suited to rapid mapping of ore hardness in geometallurgical and comminution applications.

Jan 1, 2012

By T. R. Kostecki, J. Hirschi

"Analytical engineering design is based upon a trial-and-error iterative and deterministic process. Within this process, the engineer obtains some estimated values, plugs them into de facto closed-form equations, and receives output, which is expected to be a single number that serves as the basis for the design. This number is typically a factor of safety, or some other equivalent strength-stress ratio. This provides the engineer with a quick and relatively quantitative design methodology. This can create problems however, because in mining applications, the actual in situ system is highly variable, complex and often chaotic, which can lead to potentially incorrect conclusions that result in unsafe designs. A more appropriate and reliable approach is a probabilistic analysis for engineering design. This process is used widely in civil and other engineering disciplines, but is often overlooked for applications in coal mine design. Additionally, it seems the amount of past studies using this approach, especially in coal mine design, are rather limited. Considering how the probabilistic approach can account for uncertainty in parametric values and how unpredictable a mining design can be, the authors believe that this approach has potential in mining. This paper will focus on a summary of past studies related to probabilistic analysis in coal mine pillar design and provide recommendations for future work that could improve design reliability. INTRODUCTIONFeasibility and fundamental design procedures for excavations often start with an assessment of mine openings, pillar design, and the surrounding structure by using a deterministic approach with closedform solutions (ex. Bienawski, Obert-Duvall). These are reliable methods, but designers know that the inputs in these closed-form solutions are estimates at best and do not incorporate any degree of uncertainty. This is therefore not an optimal design procedure.A more appropriate design should incorporate some uncertainty because of the chaotic and variable nature of geology and mining conditions in general. In an attempt to account for uncertainty, a probabilistic approach can be adopted, which accounts for deviations in variables and provides a more optimum design solution. By applying a probabilistic approach, a designer can look at multiple failure scenarios at the same time instead of using the same deterministic design over and over."

Jan 1, 2015

By C. W. Eggert

This paper gives an account of the E.V.O.P. tests made at the Copper Rand mill of the Patino Mining Corporation in Chibougamau, Quebec. The runs were made to acquire an understanding of the method. A description of events, along with conclusions, observations and opinions, is out-lined.

Jan 1, 1967