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By V. I. Lakshmanan

Process Research ORTECH Inc. (PRO), with its in-depth knowledge on cobalt behaviour in nickel matte smelters and its novel mixed chloride hydrometallurgical processing, is developing a hybrid process to enhance cobalt recovery. PRO’s experimental data is compared with plant information on cobalt behaviour in smelters. In final stages of iron rejection in the converters, the thermodynamics of the matte-slag system dictates the undesirable transfer of the cobalt to the final converter slags. This results in much lower cobalt recovery in the product Copper/Nickel matte (<60%) in present copper and nickel smelters. This information is used to transfer cobalt into desired quantity of converter slag. The enriched cobalt slag is subjected to PRO mixed chloride process to recover nickel, and cobalt as high value salts of importance in lithium ion batteries. From a typical converter slag containing 3.5% Ni, 1.5% Co, and 1.0% Cu, PRO leach process extracts 98 % Ni, and 98 % Co, and 99% Cu. Application of this process to enhance cobalt recovery in typical Copper/Nickel smelters is presented. In addition, this will also enhance the Copper and Nickel recovery. Both these aspects are of interest to the Copper, Nickel, and cobalt producers. INTRODUCTION In pyrometallurgical extraction of copper and nickel from sulphide ores cobalt often occurs with copper and nickel. The requirement of cobalt is increasing due to its need in lithium ion cells used in electric vehicles. Therefore its efficient and economical extraction in a form suitable for use in lithium batteries is of great interest at present. In the pyrometallurgical processing of copper and nickel sulphide concentrates the concentrate is smelted to produce a furnace matte, which is then sent for converting to remove the iron to produce iron free (~1% Fe) matte for further processing to copper or nickel matte. The copper/nickel matte is processed for metals recovery by hydrometallurgical or vapo-metallurgical or oxidation – reduction routes to make market products. As shown in Figures 1 and 2 the slags are produced in the smelting step and in the converting steps. The metal losses in smelting are controlled by the oxygen pressure in that step and slag production which is controlled by concentrate grade. The slag produced in the converting step which is carried out at a higher oxygen pressure contains higher level of metals is often returned to the smelting step to increase value metals recovery.

Jan 1, 2019

By J. Dong

"Xanthate is a sulfide collector that has been widely used in flotation for almost a century. It is inexpensive, easy to synthesize and apply, and produces good metallurgy in the right applications. However, a major drawback of xanthate is that it decomposes easily and generates CS2 gas in transportation, storage and operation, which can be harmful to human health. Also, excessive xanthate in tailings pond leads to toxicity of the process water and potential damages to aqua-life systems. New regulations in Ontario require that the TWA (time-weighted-average) value of CS2 in the work place is below 1 ppm, which is 1/10 of the previous limit. The stringent regulation may eventually sweep other regions of Canada with the increased awareness of healthy working conditions and environment protection. Therefore, it becomes very important to find xanthate replacements which will be “green”, i.e., environmentally friendly.In this research work, a systematic procedure is used for collector evaluation using the Sudbury nickel sulfide ores from Vale’s Ontario operations, starting with the collector properties (MSDS) evaluation, followed by batch flotation tests, miniplant tests, plant trials and economic evaluation. It is found that the most promising xanthate replacement is dithiocarbamate.INTRODUCTIONSulfide mineral flotation has been practiced since the early 20th century. Its industrial importance is well recognized as mineral concentrates from flotation can be economically smelted and refined to provide primary metals. Collectors play a vital role in froth flotation. There are reagents possessing both a polar group that binds them to the mineral surface and a nonpolar group that is oriented away from the surface to attach air bubbles. The introduction of xanthate as a sulfide collector in 1925 was a remarkable development in froth flotation (Keller, 1925). It is low cost, easy to synthesize, water soluble, simple to control in application. Most importantly, it has strong capability and usually good selectivity for sulfide mineral flotation, which have been keeping its application prominent for almost a century."

Jan 1, 2011

By Adil Aledresse, Louis Mercier, Laxman Amaratunga

"The development of high capacity adsorbents with uniform porosity denoted, MP-HMS (Mercaptopropyl – Hexagonal Mesoporous Structure) using nanotechnology, and their ability to extract gold from solution, is presented. The preparation of highly effective heavy metal ion adsorbents by the incorporation of thiol moieties into the pore channels of mesoporous silica molecular sieves has been the subject of many nanotechnology research investigations. The unique feature of these nanoporous adsorbents is their ability to adsorb gold ions from ultra-low concentration solutions like mine effluent as well as from leached solutions in gold mills. The preliminary studies from laboratory simulated gold solutions show that the adsorption capacities of these materials are also among the highest reported. MP-HMS has shown the capability to adsorb 370 mg gold per one gram of the nanomaterials from Tetrachloroaurate solution (up to 37% of their weight). Experimental studies indicated that the maximum adsorption of gold (as high as 99.9% recovery). The current studies will be extended to investigate the interaction of ionic gold complexes with nanomaterials. Future development of this work may lead to either to replace the conventional CIP/CIL processes or use nanomaterials in tandem with the former, suggesting plausible use of mesoporous material in pulp, MIP or in leach, MIL, as a novel gold extraction process.INTRODUCTIONGold typically occurs at very low concentrations in ores less than 10 g/t or 0.001% (mass basis). At these concentrations the use of aqueous chemical (hydrometallurgical) extraction processes is the only economically viable method of extracting the gold from the ore. Typical hydrometallurgical gold recovery involves a leaching step followed by the separation of the gold bearing solution from the residues, or adsorption of the gold onto activated carbon adsorbent. After elution from the activated carbon the gold is further concentrated by precipitation or electrodeposition."

Jan 1, 2008

By Polysius AG

"The Lone Tree demonstration was an important milestone in bringing High Pressure Grinding Roll (HPGR) technology into hard rock applications in the mining industry. HPGRs have become standard equipment in the cement, iron ore, and diamond industries over the past fifteen years, but their use in severe duties found in the hard rock mining sector has been restricted due to high roll wear and subsequent low availability. HPGR availability has historically been limited because of frequent downtime for edge weld rebuilding as the rolls wore and short tyre life from high roll surface wear rates.Recent advancements in HPGR wear protection are now being evaluated for commercial applications in the gold and copper mining industry where this technology may offer benefits in comminuting hard and/or abrasive ores and in improving metal recovery in heap leaching applications.Proving the feasibility of HPGRs for processing competent, abrasive gold ore, Newmont Mining Corporation, the world's largest gold producer, operated an HPGR demonstration plant employing a POLYSIUS (POLYCOM) HPGR incorporating some unique wear protection, at their Lone Tree gold mine near Winnemucca, Nevada. Results of the successful demonstration are presented and evaluated in this paper.The Lone Tree HPGR demonstration plant operated for three months, from April through June 2003. The HPGR operated for 1626 hours and processed 141,000 tons of ore. This technology demonstration focused on measuring operating performance, wear characteristics, and availability of today's HPGR technology.Polysius' innovative roll surface wear protection system eliminated edge-welding downtime. Improved surface wear protection extended tyre life to predicted durations acceptable for very abrasive service. The POLYCOM HPGR is now deemed suitable for selected hard rock applications."

Jan 1, 2005

By E. S. Yan, R. Graley

"The StackCell was developed to overcome the engineering and design challenges that are commonly associated with existing flotation technology such as pneumatic, self-aspirating cells, mechanical cells, and flotation columns. These challenges include high energy consumption, large floorspace requirements, and size. They are most evident when designing systems to process streams containing a high volumetric flow rate coupled with a significant float yield. Unlike many metalliferous and industrial mineral applications, fine coal flotation circuits are typically characterized by feed streams containing a low solids content (<5%, by weight) where up to 85% of the feed can report to the product launder. With input from major engineering houses and end-users, the Eriez Flotation Division (EFD) developed the StackCell technology with the goal of providing an additional flotation option for end-users. This technology was designed specifically to overcome these challenges by providing an efficient method of separation in terms of metallurgy, but also with respect to equipment size, energy consumption, and installed costs. Besides being placed in tandem with existing cells to provide cost-effective supplemental capacity, this technology can be installed in a stand-alone arrangement as recently demonstrated at Patriot Coal’s Kanawha Eagle preparation plant. This manuscript provides an understanding of the underlying fundamentals of this new technology and presents data from Kanawha Eagle in addition to other industrialscale installations.INTRODUCTIONOver the past decade, column flotation has continued to gain acceptance as an alternative method for recovering fine coal due to superior metallurgical performance as compared to mechanical flotation cells. This point has been proven on numerous occasions by comparison of plant flotation data with the release analysis separation curve (Dell et al., 1972). Data from a release analysis test approximates the ultimate flotation response of a coal sample. In North America, a number of investigations have been published that document bottom-line improvements achieved using column cells (Luttrell et al., 1999; Kohmuench et al., 2004; Baumgarth et al., 2005). According to these reports, the benefits are derived from an overall increase in plant yield that can be achieved due to the improved product grade in the flotation circuit. In particular, the application of wash water to a deep froth utilized in column flotation minimizes the nonselective recovery of high-ash ultrafines that are hydraulically entrained in the froth by conventional flotation machines."

Jan 1, 2013

By L. Li

The rock quality designation (RQD) was initially introduced by Deere (1963) for civil engineering. But, its application has been largely extended to rock mechanics and has become a fundamental parameter in geotechnical engineering (e.g., Hoek & Brown 1980; Milne et al. 1998). The success of this definition is due, in great part, to its simplicity. However, this index includes a number of limitations. Among these limitations, a critical one is associated with the arbitrarily selected threshold value (e.g., Priest & Hudson 1976). Consequently, the RQD value would vary with different threshold length for the same core. Also, using the customarily and universally adopted but very arbitrarily selected threshold value of 10 cm (for NX cores) in the assessment of RQD, the RQD values usually tend to be either high or low in most rock engineering. Some intermediate values (50%) are less frequently encountered (Harrison 1999). The original definition of RQD does not well represent the actual quality of rock masses. In this paper, an improved definition of rock quality designation (RQDc) is given.

May 1, 2009

By Marc D. Melker, Geoffrey R. Lane, Michael Jahraus

"The Cresson gold deposit is located in the Cripple Creek district of Colorado. The deposit is composed of volcanic intrusive rocks and volcanogenic sediments where gold mineralization is associated with veins and cavities within a diatremal breccia.The purpose of the current study was to:1. Determine the penetration potential of the Cripple Creek Breccia.2. Assess the relationship between penetration and gold recovery within the Breccia.Two methods were applied using a cyanide solution containing ultraviolet sensitive dye to elucidate pathways of penetration within the rock. The first involved stagnant soaking of twoinch square pieces within the solution. The second method involved column leaching of ~100kg of Breccia crushed to P80 12.7 mm (0.5 inch). Samples were selected at specified intervals to capture the penetration progress of the solution. Photomicrographs and image analysis were utilized to illustrate and quantify the degree of penetration.Results indicated that the maximum penetration for the Cripple Creek Breccia (85 to 97%) due to a porous and permeable groundmass, containing large non-porous lapilli fragments. In addition, ~90% of leachable gold was recovered with only ~50% rock penetration.INTRODUCTIONDye penetration studies were first developed at SGS-Lakefield Research for the purpose of determining the fluid penetration amenability of differing rock types. The method was to place a large rock or drill core in a pan with 1 to 2 inches of a pre-mixed, water based fluorescent dye. The sample was sequentially cut after prescribed time periods to reveal a fresh surface. The cut surface was photographed under long wave ultraviolet light, and the same piece returned to the dye and allowed to sit until the next prescribed cutting."

Jan 1, 2006

By R. Bruce Ferguson

"IntroductionThe Beaverlodge Operation of Eldorado Nuclear Limited is a uranium property located near the north shore of Lake Athabasca about 7 miles from Uranium City, Saskatchewan.The mill is a 2000 tpd carbonate leach operation producing a high grade yellowcake concentrate.The Lamella Thickener was purchased to replace a 55 foot conventional unit which had deteriorated beyond repair. The cost of the unit was considerably lower than for a conventional unit, installation was much simpler and the unit is much more compact allowing it to be installed in the mill basement and be insulated completely.The unit was sized according to the results of tests performed both by the supplier and Beaverlodge engineering staff. The supplier guaranteed overflow clarities of less than 100 ppm suspended solids. The Lamella thickener was developed by A. Johnson Co. of Stockholm, Sweden, is manufactured under license by Parkson Corporation of Ft. Lauderdale, Florida and is distributed in Canada by A. Johnson Co. of Montreal."

Jan 1, 1975

By Janis A. Shandro

The mining sector is a major economic driver for Canadian, and British Columbian communities. In parallel strong commitments have been made by industry to the well-being and sustainability of associated communities. However, these dimensions are the least understood. Especially lacking are focused regional investigations that compare the well-being and sustainability of communities dependent on different resources sectors. It is hypothesized that this type of comparative analysis will help to foster a greater understanding of what makes a resource or mining community healthy and sustainable. This paper describes research that examined community-level indicators associated with well-being (e.g. education, income and employment) and sustainability (e.g. economic diversity). The indicators were derived from Canadian Census data for 31 British Columbia resource-based communities (with a focus on mining) during a period of time (1991 to 2001) when resource sectors experienced an economic downturn. Our findings identify that during this decade, mining communities differed significantly from other resource-based communities, and comparative analysis of census derived indictors illuminate challenges that mining communities in British Columbia face with respect to wellbeing and sustainability (such as economic diversity, unemployment, and population loss). To contribute to the mining sector?s efforts towards meeting their commitments to communities, this paper concludes by proposing strategic opportunities aimed at the enhancement of mining community sustainability for policy-makers, communities, and the mining industry to consider.

May 1, 2011

By O. A. Bascur, J. Patrick. Kennedy

"The lack of integration of mining and metallurgical information at sufficient detail to act is a problem. Without such data, mine cut-off grade can not be optimized on a per grade basis. It is difficult to determine economics without integration of mine transactions, stockpile inventories, process flows and assays. Actions also require real time information from manufacturing assets, but corrected for gross errors from trucks, shovels, conveyors, faulty sensors, bad instrument calibration. Validation methods must include process models to identify corrupt actionable information. This paper presents new tools that use the model the process to sift through available data, identify and eliminate gross errors, and use statistical data reconciliation to create material balanced, internally consistent values. Uses of models allow data to be unified for useby both monitoring and decision making processes.A Real Time Performance Management (RtPM) uses unifying analysis methods to empower everyone in the organization with unparallel real-time intelligence, enabling them to continuously improve performance.BACKGROUNDExtraction of metals has become a global business; new economic and environmental forcing factors are present today which were unheard a couple of years ago that are causing companies to focus on plant operations. High ROI actions can be achieved internally which will increase mining and metallurgical processing unit efficiency and reducing operating costs if the proper information is provided those in the complex that can act. Large changes are possible with many of these small steps if the barriers for action are removed. The chief impediments are lack of infrastructure including the data, computing tools and essential data and bad information.Increased demands will be placed on the types, quantity and priority of information. Metallurgical complexes are attempting to become better neighbors, increase productivity, improve customer service, and satisfy the regulators and compliance groups -- all with fewer people and less costs."

Jan 1, 2004

By Deon van Tonder, Chuck Edwards

"Solvent extraction is used in many acid leach uranium circuits to upgrade and purify the uranium bearing solution prior to final product precipitation. A number of strip options are available to recover the uranium from the loaded organic. This paper compares some of these options on the basis of typical capital and operating costs for both the solvent extraction circuit and downstream uranium processing, and also considers other related issues. The aim is to provide an objective comparative assessment of these options that could be used as a qualitative guide in process selection or improvement.INTRODUCTIONIn the 1950s the uranium industry was the first industry to adopt solvent extraction (SX). Since then, the flow sheets have advanced. Notable was the introduction of tertiary amine extractants by General Mills during the late 1950s and 1960s (Mackenzie, 1997; Mackenzie, 2005), which is still today considered ‘state of the art’ technology. Initially solvent extraction was done in combination with ion-exchange, such as in the Eluex flow sheet, followed later by the adoption of direct solvent extraction from pregnant leach solution (PLS). From a strip-precipitation perspective ammonia strip followed by ammonium diuranate precipitation was widely adopted as the norm in the uranium industry. More recently alternative strip systems have been receiving increasing attention due to the environmental, health and safety issues associated with ammonia and the resulting calcined uranium oxide product. This paper explores some of these alternative options in comparison with the ammonia route.It is important to acknowledge that each operation is unique, and therefore the information and philosophy outlined in this paper serve to provide a general guide that can be potentially applied and adapted to any site or project."

Jan 1, 2013

"Drilling twinned holes is a traditional technique used for verification of intersections of high-grade mineralization, testing of historic data, or confirmation of drillhole data during geological due diligence studies. Twinned holes can also be used for special tasks such as correcting earlier data that are recognized to be biased. Successful implementation of the twinned-holes technique requires thorough planning. Experience suggests that good practice is to drill twinned holes no more than 5 m apart. Many unsuccessful twinned-holes programs could possibly have failed because the twinned holes have been drilled too far apart.Twinned holes are best compared by mineralization intersections and, if the data and geological characteristics of the deposit permit, by samples, equal-length composites, or geological units. Variables to be verified by twinned holes should include the thicknesses of the geological units of interest (e.g., mineralized thickness) as well as the presence of significant geological features (e.g., ore/mineralization contacts, alteration, etc.).A formal, rigorous analysis of twinned-hole data is essential. Repeatability of sampling, analytical results, and bias must be analyzed and statistically quantified. The number of twinned holes required for conclusive statistical and geostatistical analysis can be as high as 20-30, in particular where the studied variables are characterized by high short-range (local) variability.The efficiency of this approach is demonstrated by several examples of successfully applied twinned-hole projects, including applications to orogenic gold, mineral sands, bauxite, and iron ore deposits."

Jan 1, 2009

By K. L. Murphy, G. Multamaki, P. M. Huck

"A preliminary evaluation, based on existing data, has been made of the implications of placing radium-barium sludge in tailings areas. The study was restricted to a consideration of possible increases in the quantities of radionuclides escaping to the environment through either groundwater or surf ace water, considering the types of tailings treated and the effluent treatment systems currently operating in Canada.IntroductionIn the recovery of uranium from ore deposits, the tailings produced by mine/mill complexes are conveyed to impoundment areas in slurry form. After settling, the supernatant is discharged to the environment together with runoff from precipitation on the tailings bas in. Currently, all operating uranium mines in Canada employ barium chloride treatment to control the release of dissolved radium to the aquatic environment. The dissolved radium in the tailings decant is precipitated with barium chloride, forming (Ra,Ba)SO4, and allowed to settle in ponds or lakes. In some instances, settling tanks have replaced ponds and flocculants have been added to aid settling. Because the Atomic Energy Control Board does not consider the precipitation ponds to be suitable for final disposal of these sludges, acceptable sites must be found. Options which have been suggested for sludge management include underground placement either in worked-out mine areas or in special chambers, or placement in the tailings areas. Conceptually, the latter alternative is attractive and probably would minimize sludge handling. This alternative would be subject to the AECB policy which requires that upon abandonment, radioactive releases from a tailings area must be within present regulatory limits and that treatment to meet these limits should not be required in perpetuity.No quantitative data exist concerning either the effect of physical and chemical conditions in the tailings on resolubilization of radium from precipitated sludges or the fraction of this additional radium which would be released."

Jan 1, 1982

"Geoscan is used for multi-elemental analysis of conveyed bulk materials in the minerals industry with proven performance and demonstrated paybacks of weeks or months in iron ore, manganese, copper, zinc-lead and phosphate industries. Geoscan-M measures continuously through the full bed depth and is unaffected by belt speed, particle size, layering, mineralogy and dust levels. Increments of typically two minutes are accurately measured and provide the plant operators with tonnage weighted results of contained elements. Measurement of the composition in real time enables prompt feedback to the mining operators and also feed forward to the process operators. Crushed ore increments can be diverted based on composition, such as diverting waste for disposal or marginal material to a stockpile for separate processing. Bulk sorting allows material to be placed into relevant stockpiles for subsequent blending to achieve consistency for process feed. Parameters used for decisions may be primary metal content, deleterious component content, other process parameter, or a combination of these. Process parameter may be the elemental ratio between critical components, e.g. Cu:S ratio, basicity, or the content of an “indicator” element (such as Si indicating material hardness). Benefits will be discussed based on case studies in copper and iron ore.IntroductionAs operators of process plants strive to remain competitive as capital and operating costs increase and commodity prices fluctuate, more focus has been directed at incremental performance improvements at incremental cost rather than major expansions to increase output. The philosophy of working smarter allows plants to adopt technologies proven in other industry sectors to minimise risk. This paper discusses one such technology that the minerals sector is adopting and has found to be safe, reliable and accurate with paybacks of weeks in most applications. New applications continue to be found and major benefits realised at various stages in the processing and handling of ores and products."

Jan 1, 2016

By Gabka T., R. E. Gregorczyk

Work to improve employees' behavior in Głogów Copper Smelter began in 2009. It has been noted that over 90% of accidents at work are attributable to human reasons. At that time, a series of external workshops was contracted based on exercises conducted by a psychologist trainer with supervisors. Having trained about 300 employees, an observation of employee behavior at workstations was started as part of the control of risk reduction measures. As a result of the above actions, the number of accidents was reduced by half between 2009 and 2017. Currently, internal workshops for communication improvement for behavioral auditors are conducted by the employees of the Smelter. Named: "I observe, react and communicate" and aimed at further mastering the elements of the safety culture in Głogów Copper Smelter. INTRODUCTION KGHM Polska Miedz is an integrated mining and smelting copper producer based in Poland and operates on the international metal market. KGHM, with annual production of over 500 thousand tonnes of copper, holds a middle position in the world ranking of copper producers. At the same time, in Europe it is the largest producer of copper from its own ore deposits, possessing its own integrated production structure, from underground mining operations to final, top-quality product. It is also worth mentioning that KGHM Polska Miedź is one of the largest Polish exporters and, apart from copper, is a significant primary silver producer in the world. The mission of our company, consistent with its strategy, is to produce copper and silver in a safe mode for workers and the environment, with reduced environmental impact. Therefore, "Głogów" Copper Smelter operations are continuously focused on the creation of safe working conditions, and minimizing the negative effects on the environment. The company meets the requirements of an Integrated Management System comprised of the following: Quality Management System ISO 9001:2008 Environment Management System ISO 14001:2004 OHS Management System according to the requirements of BS OHSAS 18001:2007 Being a proud socially responsible company, we are aware that part of an efficient OHS system is to recognize, monitor, prevent, educate and motivate, thus continuously improve working conditions for 2500 employees of Głogów Copper Smelter &Refinery. We clearly communicate that a low accident rate is beneficial for both, staff and the company, and is of utmost importance as a part of our health policy.

Jan 1, 2019

By Martin Stoklossa

Surface mining operations typically require run-of-mine material to be sized for further processing. In-pit crushing facilities serve this need, as stationary, semi-mobile or fully mobile units. Although in particular fully mobile crushing facilities have been in use for over half of a century, other surface mining techniques have typically been implemented. However, with increasing operating costs in truck and shovel operations, and other economic considerations, mobile crushing plants are increasingly a viable option. The operational and economical parameters in relation to the optimal surface mining equipment selection will be reviewed. The role of the mobile crushing technology within the continuous vs. noncontinuous surface mining operation and basis for mine planning are also discussed. Current applications and respective case studies will be reviewed. Key performance indicators will be presented. These performance parameters can be viewed as a tool to aid in the equipment selection process. The future direction for further research and development in mobile crushing facilities will also be presented.

May 1, 2008

Westwood Quebec Long Life, Low Cost CONSTRUCTION UPDATE ? Shaft advanced to 840m (after 1 year), 3 km of down ramp and 2 km of exploration drift ? Head frame and hoist room structure completed ? 2009, 84,700m drilling program completed (increase 9%) 2010 OUTLOOK ? $102 million expenditures planned ? Shaft to advance to 1,300m and the first loading excavate 71,500m drilling program planned

May 1, 2010

By Véronique Falmagne

The mining sequence at Noranda?s Bell-Allard mine calls for two mining fronts retreating toward a central pillar known as the Retreat Zone between pyramids A and C. It is clear from numerical modeling and rock mass characterization that the induced stress level in the pillar will exceed the rock mass capacity. A mining plan was developed including the re-dimensioniong of stopes in the Retreat Zone, additional ground support and instrumentation in order to ensure the safety of the workforce and to maximize ore recovery while minimizing production delays. The mining strategy consists in allowing the rock mass to fracture and fail progressively while maintaining control of the existing openings with the appropriate support. A systematic analysis of rockbursting and caving hazards was conducted for all accesses and stopes in order to plan ground support and instrumentation needs.

May 1, 2003

By Pavel Vasak

Microseismic monitoring has become standard practice in the mining industry as a ground control monitoring tool at depth. Translating the information into practical hazard assessment tools for the rock mechanics practitioner is the focus of research jointly conducted at Creighton Mine by INCO Mines Technology Centre (MTC) and the Geomechanics Research Centre (GRC) in Sudbury, Ontario. Rock mass damage mechanisms are typically related to stress and the presence of geological structures. Due to well executed de-stress blasting practices at the mine, stress related problems are minimized. However, structurally related damage mechanisms associated with shear zones, faults and joints pose a substantial hazard. Identifying active structures from the dataset of seismic and microseismic events is generally problematic. We propose a new methodology that uses a combination of spacetime event density, hierarchical clustering and principal component analysis to identify planes of microseismic activity, termed active planes (APs). Once identified, the presence and intersection of active planes can be used to provide a hazard ranking for nearby excavations. The ranking is based on the standard Q rock mass classification system, with emphasis on the joint set number (Jn) and stress reduction factor (SRF) parameters. If the rock is treated as a fractured continuum, then, the Jn indicates the degree of freedom for blocks to move and hence, increased potential hazard. An increased hazard can also result if the APs are larger-scale and discrete (faults) rather than ubiquitous (joints). In this case the SRF is used as a measure of the degree of looseness in the rock mass.

May 1, 2004

By T. G. Paradis, C. A. Mohns

"This paper summarizes the Wren CAT (Clarifier and Accelerated Thickener) deep bed thickener operation at the EKATITM Diamond Mine in Canada’s Northwest Territories. EKATITMs’ thickener project is presented in terms of initial design considerations and present day operating practices. A circuit description summarizes process equipment, reagent systems, and typical process conditions, and details of Wren CAT operating principles are provided. Operating strategies are discussed, with emphasis on process instrumentation and control and operating challenges.INTRODUCTIONThe EKATITM diamond mine, operated by BHP Diamonds, Inc., is located in the Northwest Territories near Lac De Gras, approximately 300 km NNE of Yellowknife, NT. 9000 dry metric tonnes of diamond-bearing kimberlite ore are processed daily. Processing operations commenced in October, 1998.The EKATITM process plant flowsheet features typical steps in diamond recovery plant design. Figure 1 shows the general plant flowsheet. Size reduction and feed preparation are accomplished by crushing, scrubbing, and high pressure grinding rolls (HPGR) through closed-circuit classification with vibratory screens. Heavy medium separation (HMS) is used as the initial stage of heavy mineral concentration. Secondary concentration is accomplished in the recovery plant by attrition milling; wet, high-intensity magnetic separation (both wet and dry); and X-ray sorting.The present budget throughput rate is 9000 dry tonnes per day. This will be increased to 18,000 tonnes during the first ten years of operation. Unlike most kimberlite treatment facilities, which process material from a single ore body, EKATITM’s process plant was designed to accommodate ore from five different kimberlite pipes, each with its own treatment characteristics.All processing, except for primary crushing, is carried out in a temperature-controlled environment in the main process plant building."

Jan 1, 2000