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By Iain G. Bruce

The need to improve supply reliability while improving our environmental record during the past half decade of low metal prices has required the mining industry to prioritise expenditures. Quantitative Risk Assessments using third party reviewers and specialist risk management teams have assisted in identifying hazards that can both disrupt supply and impact the receiving environment. Graphical displays using risk ellipses can simplify the presentation of the results in a Probability-Consequence (PC) graph. Development of risk acceptability envelopes using readily available financial data superimposed onto the same PC space assists management to prioritise their risks and focus on risk reduction measures. Development of this system and examples of the successful implementation of the system from several recent projects are described.

May 1, 2003

By T. R. Kostecki

"Instrumented rock bolts are effective tools for assessing the reinforcement and condition of immediate roofs; however, instrumentation can have relatively high costs, which can be justified by high reliability and repeatable and representative data measurements. The instrument’s durability and operational life are of great importance, along with accuracy, applicability, and usefulness. This paper develops reliability models for three instrumentation technologies used in slotted rebar, drawing data from studies at five underground coal mines. Three case studies demonstrate instrument applicability and usefulness. Finally, two types of instrumented rock bolts are used to determine the direction of bend and maximum bending strain. RÉSUMÉ Les boulons d’ancrage instrumentés sont des outils performants qui permettent d’évaluer la consolidation et la condition des toits immédiats. L’instrumentation peut cependant se révéler très onéreuse, des coûts qui se justifient par sa fiabilité élevée ainsi que par des mesures de données reproductibles et représentatives. La durabilité de l’instrument et sa durée de vie opérationnelle sont très importantes, de même que son exactitude, son applicabilité et son utilité. En s’appuyant sur des données issues d’études menées dans cinq mines de charbon souterraines, cet article développe des modèles de fiabilité pour trois technologies d’instrumentation utilisées pour des barres d’armature nervurées. Trois études de cas démontrent l’applicabilité de l’instrument et son utilité. Enfin, deux types de boulons d’ancrage instrumentés sont utilisés pour déterminer la direction de la flexion et la contrainte de flexion maximale.INTRODUCTION Using instrumented rock bolts to monitor strain changes in a rock bolt array allows engineers to understand the per-formance and effectiveness of the rock reinforcement system and the response of the rock mass to such support; however, instrumentation remains a niche solution for solving complex ground-control problems—particularly for underground coal mines, which is where they are needed most. From 2000 to 2016, fall-of-ground fatalities still accounted for an average of approximately 30% of the total annual underground coal mine fatalities in the United States alone (United States Department of Labor, 2018). These tools would also be useful for deep hard-rock mining conditions. The main reasons for the lack of widespread use are not only cost but also accuracy, applicability, implementation procedures, intrinsic permissibility, and reliability (Peng, 2015). As a result, measurements of coal mine roof behaviour using instrumented rock bolts are quite scarce, not widely published, or inadequately presented to provide a seamless understanding of a roof’s response to support."

Jan 1, 2018

By Mike Samuels, John Starkey

"This paper examines test results and grinding mill design for the recent Fortune Minerals’ NICO Project, located in the Northwest Territories. SAG milling and rod milling options are compared. Rod milling is clearly shown to be the best option because of the ore’s extreme resistance to breakage in a SAG mill environment.Surprisingly, the Bond Ball Mill Wi was 13 kWh/t for this ore. The Bond Rod Mill Wi was 20 kWh/t, whereas the SAG pinion energy to grind the ore to T80 1.7 mm was 30 kWh/t. The existence of ore with this ratio of SAG hardness to Bond BM Wi has not been previously observed. If not considered, this critical relationship may adversely impact the accuracy of mill design. This paper substantiates the significance of these findings to achieve successful grinding design on ore that is macro-competent during primary size reduction, but relatively normal during secondary grinding.INTRODUCTIONThe NICO Cobalt-Gold-Bismuth-Copper deposit is located 160 km northwest of the City of Yellowknife, Northwest Territories. It is the largest IOCG-type deposit (aka Olympic Dam-type) currently recognized in Canada with Mineral Reserves of 21.8 million tonnes contained within a larger 57 million tonne, lower-grade Mineral Resource. The project, owned 100% by Fortune Minerals Limited, has been assessed in a positive definitive feasibility study, subject to underground test mining and pilot plant testing, and is now in the permitting stage to develop a combined open pit and underground mine and process plant. An updated process flow sheet incorporates conventional crushing, grinding and bulk flotation, followed by filtration for shipment of a concentrate to a purpose-built refinery proposed to be built near Saskatoon, Saskatchewan. At the refinery, separate bismuth and cobalt concentrates will be produced following regrinding. The hydrometallurgical process methods include: pressure acid leach, precipitation, ion exchange, and electro-winning for recovery of cobalt as 99.8% cathode; solvent extraction and electro-winning of by-product copper cathode; ferric chloride leach and electro-winning for recovery of bismuth as 99.5% cathode; and cyanidation of the leach residues for recovery of gold as doré."

Jan 1, 2010

By Manqiu Xu, Glen Robertson, Steve Wilson, Pete Quinn

"The middlings circuit, once called the pyrrhotite rejection circuit, at Inco’s Clarabelle mill was a single flotation stage. It used to process a combined feed consisting of the main flotation scavenger concentrate and the non-magnetic portion of the magnetics flotation circuit tails. The typical circuit metallurgy was 55% nickel recovery at 6.5% Cu+Ni concentrate grade. In the past few years, a research project with the objective of improving the circuit metallurgy was initiated between Inco’s research laboratory and the Mill’s Process Technology group. This project has gone through three steps: a) initial laboratory studies, b) on-site pilot plant investigation, and finally c) full plant implementation.The present paper describes the initial laboratory test work. The development of a two-stage circuit consisting of separate rock and pyrrhotite rejection stages to replace the simultaneous rejection of both rock and pyrrhotite in a single stage is discussed. A two-stage circuit simulation based on batch laboratory flotation data is also presented. Further development work, including the on-site pilot plant test work and the plant implementation of the new circuit design, will be described in a later publication.INTRODUCTIONThe milling operation at Inco’s Clarabelle mill, Copper Cliff, Ontario processes a rich complex sulfide ore from several large production mines around the Sudbury basin (Agar, 199 1). The sulfide mineralization is simple, consisting of chalcopyrite (Cp), pentlandite (Pn) and pyrrhotite (Po). The main gangue minerals are pyroxene, feldspar and quartz with minor amphibole and talc. Estimates of mineral composition are routinely calculated from Cu, Ni and S assays. In the mineralogical calculations, all gangue minerals are conveniently grouped and treated as rock (Rk)."

Jan 1, 2000

By Donald Leroux, Jean-François Wilhelmy, Ahmed Bouajila

"A young private R & D organization, COREM celebrated its 10th anniversary in 2009. Managed by a consortium of nine mining and metallurgical companies, COREM has the mandate of increasing the competitiveness of its member companies through the development and transfer of mineral processing innovations. Typical technologies developed by COREM include alternative mineral processing techniques, novel operating strategies, innovative sensors and process simulation software. Many of them were developed in partnership with universities and selected research organizations.Because the COREM membership base is broad (from ferrous to base, to precious metal industries), its R & D program must deliver technologies with applications within a wide spectrum of mineral processes. Comminution, physical (gravity and magnetic) separation, flotation, cyanidation, pelletizing and thermal processes are the main topics of the R & D program. A number of new technologies have been developed and transferred to the plants of member companies. These examples of transferable technologies demonstrate the capability of COREM to impact the bottom-line of its member companies.INTRODUCTIONCOREM is a private mineral-processing R & D organization that operates from its own laboratories and pilot-plant with its own staff of professionals and technicians (about 95 persons). It is managed and financially supported by a consortium of nine mining and metallurgical companies and three provincial and federal ministries. The very ‘down-to-earth’ mission statement of COREM is to increase the competitiveness of the mineral processing plants of its members. The eighteen plants upon which the COREM technology development program is currently based can be found in Québec, Newfoundland and Labrador, New Brunswick, the Netherlands and Botswana."

Jan 1, 2010

By G. N. A. Senhorinho, J. A. Scott, C. A. Laamanen

"Closed mine sites are widely regarded as a negative asset due to their legacy of environmental impacts. These sites are often characterized by waterbodies with elevated metal concentrations and low pH that are traditionally considered to have little or no value. These sites are potential sources of beneficial biocompounds produced by microalgae in response to environmental stresses. A bio¬prospecting program found that certain microalgae from waterbodies near historical mine sites exhibited higher antibacterial activity than any microalgae previously reported in the literature. There is potential for the mining industry to be involved in examining features such as tailings ponds at mine sites for high-value compounds, including ones that might help mitigate rapidly growing microbial resistance to current antibiotics. ¦ KEYWORDS Antibacterial, Closed mining sites, Metabolites, Microalgae, Stressed environments RÉSUMÉ Les sites miniers clôturés sont généralement considérés comme des actifs négatifs en raison de leurs répercussions sur l’environnement. On trouve souvent sur ces sites des étendues d’eau affichant de fortes concentrations en métaux et un pH faible, généralement considérées comme ayant peu, voire pas de valeur. Ces sites sont des sources potentielles de biocomposants bénéfiques produits par des microalgues en réponse aux perturbations environnementales. Un programme de bioprospection a permis de déterminer que certaines microalgues trouvées dans ces étendues d’eau à proximité de sites miniers historiques présentaient une activité antibactérienne supérieure à celle mentionnée dans toute la docu¬mentation existante. L’industrie minière pourrait bien participer à l’examen de particularités telles que la recherche de composants à haute valeur dans des bassins de décantation des résidus sur des sites miniers, notamment des composants qui pourraient aider à atténuer l’augmentation rapide de la résistance micro¬bienne aux antibiotiques actuels. ¦ MOTS CLÉS antibactérien, environnements perturbés, métabolites, microalgues, sites miniers clôturésINTRODUCTION The mining industry is one of the largest economic drivers in the world. Within Canada, for example, it contributed 2.8% (C$57.6 billion) of the 2016 gross domestic product (Marshall, 2016). Canada also has the highest non-ferrous exploration budget worldwide (Marshall, 2016); therefore, it is likely that mining operations, mine waste disposal, and the number of closed sites will continue to grow in Canada. The environmental impact of mining operations stems from the volume of tailings produced, which can be up to 97–99% of the total volume of ore processed at a mine (Adiansyah, Rosano, Vink, & Keir, 2015). In 2010, mining was the world’s largest industrial producer of waste at a total of 65 billion tonnes: 51 billion tonnes of waste rock (mine overburden) and 14 billion tonnes of tail¬ings (Jones & Boger, 2012)."

Jan 1, 2019

By S. W. Marcuson

In the late 1960's concerns about the natural environment reached high levels within North America and provided activists with suitable platforms for exerting influence over the general public and politicians. In response a host of regulatory mechanisms were developed, statutes, voluntary measures, land grants, codes of practices etc. Emerging environmental awareness from the era provided impetus for rapid technological change that encompassed all industries, especially the base metal business. The resulting clean up impacted all aspects of copper production, dealing with issues such as waste disposal, water and air quality with specific impact on emissions of sulfur dioxide and particulate. This paper provides a perspective of these changes reviewing the macro-economic impact of environmental movement in mining with its specific implications to the copper smelting industry. The fundamental challenges that were faced by the old, but capital-intensive North American plants and the approaches taken to deal with the changing times are reviewed with special emphasis on the conceptual approach to smelter S02 abatement and different paths taken in the USA and Canada. The role of economics, sustainable R&D and presence of technical infrastructure that facilitated the change process is elucidated, and speculations are made about the future state of pyrometallurgy and the natural environment. Cu2007 -

Jan 1, 2007

By Tony Robles

"A new process is disclosed for the recovery of gold and/or silver values from activated carbon wherein they are adsorbed as cyanide complexes. A unique chemistry allows the new process to use mill process water containing an inexpensive, non-hazardous compound as the eluant. The new process has an elution period of 5 hours at 98°C. The gold in the eluant can be recovered by electrowinning or zinc precipitation. The new elution process is simple, reliable, and provides an eluted carbon that may not require thermal regeneration before reuse. Retrofitting the new process to existing processes such as Zadra, Anglo, and others will not require significant capital expenditures.IntroductionThe efficient and reliable elution process for gold/silver from activated carbon is a very important process in the gold mining industry. The most common techniques for elution of gold cyanide from activated carbon are the Zadra and Anglo procedures.Specialized elution techniques like the Micron and Acetonitrile processes have not been commercialized to significant extent probably due to relatively complex unit operations and expensive reagents.Important functions of the gold recovery circuit are:Efficiently recover gold/silver from the loaded carbon.Carbon is in good condition for reuse for optimum recovery.The pregnant solution is amenable to electrowinning or zinc precipitation to recover gold/silver from the solution.The whole process to be simple and short to reduce gold inventories.Present Elution ProcessesTable 1 shows some carbon elution processes that are available today. The two main elution processes used in the industry are: (1) the Zadra process, in which hot cyanide solution is circulated through an elution column and electrowinning cells; and (2) the Anglo American Research Laboratory (Anglo) process, consisting of a pretreatment step with caustic cyanide solution, followed by elution with deionized water."

Jan 1, 2000

By Stephen J. Roberts

Gold catalysts were prepared on co-precipitated, calcined copper oxide - zinc oxide support by an inverse deposition-precipitation method. These catalysts were characterised by X-ray diffraction (XRD) and temperature-programmed reduction (TPR) and studied for CO oxidation activity at various catalyst calcination temperatures. TPR studies of the support material exhibited a double peak and shift to lower temperatures for the reduction of Cux+ to metallic copper, as opposed to the single reduction peak for pure CuO. This phenomenon is possibly caused by an interaction with the zinc oxide. The addition of gold to the support CuOZnO led to a further shift in copper reducibility to lower temperatures. Gold present in the initial uncalcined catalyst as Au3+ was auto-reduced to Au0 under various calcination temperatures. The Au3+ reduction peak was observed to shift to lower temperatures with increasing calcination temperature. The catalytic activity was found to pass through a minimum value with respect to calcination temperature. Catalysts with both gold in entirely the 3+ or metallic oxidation state were found to exhibit high activity. Furthermore, the catalysts were found to decrease in activity with decreasing Au3+ content up to an intermediate calcination temperature, afterwhich the activity increased sharply. Possibly at higher temperatures, a stronger Au-support interaction is formed, leading to a new active site.

Oct 1, 2003

By L. C. Bird, N. T. L. Landgren, M. W. Mikhail

"Through funds made available in 1972 by the Nova Scotia Department of Mines and Energy (DME) and the federal Department of Regional Economic Expansion, a program was initiated to recover saleable coal from mine waste dumps adjacent to the existing Acadia wash plant in Stellarton, Nova Scotia.Following evaluation of these dumps in 1972, the Acadia wash plant was modified to treat high-ash material. The first production was recorded in late 1974. By the end of 1979, a total of 738,202 t of dump material had been processed, yielding a total of 205,212 t of thermal-quality coal.The successful Stellarton operation led to considering the possibility of recovering thermal coal from other dumps. Evaluation of the Westville dumps indicated total recoverable reserves of 1,346,617 t averaging 53.8OJo ash.Parameters for plant design were defined from the washability characteristics of the dump material and the results of a bulk test. Two options were proposed; one was to use the existing plant with some modifications, the other was to build a modular mobile plant that could be used at future dump sites in the province after Westville. At the 25% ash level, the potential recovery of coal from the dump was estimated at 41% yield (by weight) or 549,679 t."

Jan 1, 1981

By Bassam Kattaa

"Abstract - A heavy mineral survey of beach and dune sands including geochemical analysis for trace elements was undertaken to evaluate the economic potential of the sands and to understand the nature and distribution of the heavy minerals relative to potential source rocks. Results indicate that heavy minerals are generally derived from outcropping volcanic rocks that comprise a proportion of the hinterland in the south part of our survey area. The most abundant minerals are magnetite and pyroxene. The morphologies of the heavy mineral grains are angular to subangular, suggesting that they were transported short distances from the source rocks. Factors controlling heavy mineral distributions include wave and wind action, proximity to provenance, the fluvial drainage network, and longshore currrents.The most economically important mineral is ilmenite. Zircon and rutile concentrations are relatively minor and thus have lower economic potential."

Jan 1, 2002

By K. Galovich, P. Krivokuca

"Quinsam coal mine is located about 25 km west of Campbell River on the east coast of Vancouver Island, British Columbia. Using continuous miners in a fully mechanized retreat room-and-pillar operation, it produces low sulphur, “super compliance” thermal coal for domestic and international markets at a rate of about 2600 t/d. Currently, 65 people work at the site, including some corporate employees.Opened in 1993, the Quinsam mine had a dismal safety record until 1997. Lost time injuries and medical aids were unacceptably high. In 1998, a change in corporate structure brought a change in safety attitudes; a total and unequivocal commitment to safety as job No.1 by corporate and site management. This commitment was clearly spelled out in a new mission statement, circulated to all employees by the new President and CEO, David Slater: “Safety is job No. 1; Production flows from safety; and Think safety at all times.” As well as re-defining workplace safety practices, QCC tightened engineering controls and enforced strict adherence to mine plans.This paper provides a general background to the mining operation, and describes the safety practices that have resulted in an enviable safety record in recent years, reflected by provincial and national recognition."

Jan 1, 2004

By Brad Thrall, Howard Bradley, Michael Samuels

"LOCATIONViceroy Minerals Corporation owns and operates the Brewery Creek heap leach gold mine located approximately 55 kilometers northeast of Dawson City, Yukon Canada. Dawson was home of the Klondike Gold Rush 100 years ago. Upon startup in November 1996, the Brewery Creek Mine was the northernmost operating heap leach gold mine in North America and one of the most northern in the world. Located at 64"" 02' latitude, the mine is less than 300 km south of the Arctic Circle. Access to the mine is available at Kilometer 14 of the Dempster Highway, linking Inuvik, NWT and the Klondike Highway, 40 kilometers east of Dawson City. The immediate vicinity is the only part of Canada not glaciated in the Wisconsin advance, which has resulted in an oxide ore deposit due to approximately 80,000 years of weathering - an area unique in Canada.DESCRIPTION OF OPERATIONSIn order to utilize heap-leaching technology successhlly in an extreme northern climate, a number of design features were incorporated into the process flow sheet to operate on a year round uninterrupted basis. Winter temperature may dip below minus 50 ""C, demanding an approach to mining and leaching that is different from heap-leach operations in more temperate climates. Because of the severe winter temperatures, the mine operates approximately 2 10 days per year, while the leaching process is continuous on a year round basis. Run of mine ore (ROM) is placed on the heap beginning in mid April until late October. Overall gold recovery is projected to be 78% over a 325 day leaching cycle with annual production levels of 2.3 million tonnes of ore placed on the pad, with an average of 75,000 ounces of gold recovered per year. The recovery process utilizes conventional sodium cyanide leaching, carbon adsorption, high pressure stripping, thermal reactivation and acid washing, and on-site smelting.HISTORYFollowing a comprehensive governmental and public review of the proposed project, a Class A Yukon Water license was issued in August, 1995. Construction started in 1995 and leaching commenced in October 1996.A Socio-Economic Accord with the Tron Dek Hwech'in First Nations provides for employment, contract, and scholarship opportunities for First Nations citizens."

Jan 1, 1999

By K. Gie Tan, Frank Wright

"Misty Mountain Gold Limited (MGL - TSE VSE, MGLCF - NASDAQ) of Vancouver, owns the Harmony Gold Project located in the Queen Charlotte Islands of British Columbia. The deposit contains a mineable reserve of 2.3 million ounces of gold, at a 1.2 g/t cut-off and an average grade of 2.1 1 g/t Au.Discovered in 1970 and frequently investigated by previous owners, full-scale production has not yet occurred because of the complex metallurgy of the deposit. Recent process studies that were completed in six months at Process Research Associates Ltd. (PRA) of Vancouver resulted in significant improvements to the project viability. The work involved detailed mineral processing studies aimed at achieving a marketable concentrate. An option for bio-oxidation and cyanidation to allow on-site dor6 production was also investigated.The main findings at PRA followed the front-end recovery of finely divided free gold (Au) by gravity concentration. Approximately 20% of Au reported to less than 0.2% of the mass, resulting in a grade exceeding 500g/t Au. The resulting gravity tailing provided a uniform feed for flotation evaluation. The optimization of this step allowed for a reasonable primary grind size of 80% passing (&) 50pm. Efficient slime’s rejection was made possible by flotation at a reduced pulp density, and pre-oxidized sulphides were reactivated with Na,S. The regrinding of the bulk flotation concentrate followed by up to five stages of cleaning resulted in a combined gravity + flotation product of 50g/t Au with 82% recovery in less than 4% of the feed mass.Further studies indicated that the flotation concentrate was amenable also to tank bio-oxidation. At 65% sulphide oxidation the gold recovery improved from less than 70% to 90% by cyanide extraction using CIL (carbon in leach). This compares to less than 45% gold recovery from whole-ore cyanidation in several previous studies. Heap leaching may also be considered for lower grade material. PRA’s methodical approach and consistent results dispelled the uncertainty about predicting the material behavior for the Harmony Property."

Jan 1, 2000

By J. M. Houston

"In October 1982, Rio Algom Limited, purchased a tin prospect near East Kemptville, Nova Scotia, from Shell Canada Resources. This purchase led to the development of the first substantial tin mine in North America. This paper deals with the drillingand blasting operations at Rio Algom, in particular the use of emulsion explosives technology.This presentation describes what emulsion explosives and Heavy AN/FO are, and the support system used to deliver these products to the blast site.HistoryThe East Kemptville mine site was discovered by Shell Canada Resources (SCR) in July 1978. SCR started diamond drilling on the tin prospect in March 1979. After 8220 m of BQ drilling, it was estimated a reserve of 56 000 000 tonnes of 0.165% Sn was present.The property, which is located 54 km northeast of Yarmouth, Nova Scotia (Fig. 1), showed, after a feasibility study that, given an ore treatment rate of 9000 tonnes per day, a mine life of 17 years could be expected.GeologyThe tin deposit of the East Kemptville Mine, occurs in granitic rocks at their contact with metasedimentary rocks. The mineralization is in the form of cassiterite with associated sulphides of copper and zinc. The tin occurs in a stockwork of tin bearing Greisen alteration zones.East Kemptville MineThe mine planned an open pit operation with the first five years being mined at a rate of 14 000 tonnes per day, of which 5000 tonnes will be waste and low grade ore. Eventually, the total mining rate will be 21 000 tonnes per day, including 12 000 tonnes of waste and low grade ore. Figure 2 shows the general layout of the mine site.East Kemptville Chooses Emulsion ExplosivesIn December 1984, East Kemptville Mine awarded the Explosives Division of C-I-L Inc. a contract to supply explosives to the borehole. The system chosen gives East Kemptville the on-the-bench choice of regular AN/Fa, or a high density, Heavy AN /Fa product called SuperAN· or a water resistant emulsion explosive called MAGNAFRAC· for holes that cannot be dewatered.Emulsion ExplosivesAn emulsion is an intimate mixture of two liquids that do not dissolve in each other. Emulsions have contributed to our daily lives in such products as insecticides, salad dressings and cosmetics."

Jan 1, 1987

By J. C. Gathje

Newmont acquired the Phoenix Project through the acquisition of Battle Mountain Gold in 2000. Shortly after the acquisition, Newmont Metallurgical Services (NMS) and Nevada Operations began development work on a process to Pressure Oxidize (PDX) precious metal rich copper concentrates from Phoenix using the Lone Tree PDX facilities at Valmy, Nevada. The high precious metals content of the Phoenix concentrate - Au up to -300 g/t and especially Ag, up to -1700 g/t - led Newmont to the development of a High Temperature PDX process that achieves high cyanide leach recovery of Au and Ag, from the PDX solids, without the requirement for a messy and expensive "lime boil" or sulphate destruction process. Base metals content in Phoenix concentrates range from: 15-25 % for Cu, 1-10 % for Zn and 0-2 % for Pb. Excellent solution extraction of Cu and Zn is achieved while Pb is precipitated in the PDX residue. In addition to achieving high Au and Ag recovery this process produces very clean PDX discharge liquors that require minimum effort to remove contaminant metals and PDX solids that have superior settling and filtration characteristics. All of these factors contribute to lower capital and operating costs for the overall process. This paper describes the laboratory and PDX pilot plant developments for this process.

Jan 1, 2004

By Jacob Masliyah, Zhiang Zhou, Dharamdat Christendat, Tshitende Kasongo, Kevin Hyland, Zhenghe Xu, Ted Kizior, Douglas Cox

"A novel on-line visualization system, previously developed at Syncrude Canada Ltd., has been modified to characterize rising bubbles, particles and particle-bubble aggregates in a flotation process. With this system, the bubble size and rise velocity in a laboratory flotation cell can be determined. The technique allows the loading of solids on bubbles to be visualized, thereby providing an in-depth understanding of sub-processes of flotation. A step-by-step data processing procedure is presented. The applicability of the developed system to mineral flotation and bitumen extraction is discussed. Under batch flotation conditions in a laboratory Denver cell, three main bubble-particle attachment patterns are observed. They are: i) single particles attached to single bubbles, ii) particle aggregates loaded on single bubbles; and iii) a group of particles aggregated with a group of bubbles. The results demonstrate that the on-line visualization system is a powerful tool for understanding and diagnosing flotation processes.INTRODUCTIONAir (Gas) bubbles are an indispensable component in a flotation system. Both industrial practice and theoretical analysis indicate (Yoon, 1993; Diaz-penafiel and Dobby, 1994) that the size and population of bubbles are two important process parameters in modeling flotation. More recent investigations (Finch, et al., 1999; Gorain, et al., 1997) suggest that for a given flotation system, bubble surface area flux, defined as the air liquid interfacial area per unit time and unit cross-sectional area of flotation cell, showed a better correlation with the flotation rate constant. As a result, the bubble surface area flux is now being considered as a key parameter to account for the combined effect of bubble size and population in evaluating the performance of flotation machines and modeling flotation processes. However, the success of using bubble surface area flux in flotation process modeling largely depends on how accurate it can be determined or estimated (Finch, et al., 1999)."

Jan 1, 2000

By Sanjeeva Latchireddi, Travis Orser

"Today’s high capacity semiautogenous grinding (SAG) mills expend vast amounts of energy and in doing so consume tons of shell liners and steel balls, while processing ore. The energy efficiency of these high throughput grinding mills can be attributed to the field of breakage and slurry discharge system. The charge motion and breakage of particles inside the mill depends on the shell lifters design, while the discharge of ground particles is controlled by the grate and pulp lifters. The limitations imposed by poor grate and pulp lifter design become increasingly apparent with increasing size of ag/sag mills and their operation in closed circuit. The design of these mill components has been largely based on trial and error and hence varies considerably between manufacturers. This paper discusses the use of two state of the art design tools - Millsoft™ and FlowMod™. Millsoft™ is an effective tool to design the shell lifters and optimize charge motion, whereas FlowMod™ simulates the slurry discharge system to design grate and pulp lifters. The application of these simulators will be discussed using case studies of full scale mills.INTRODUCTIONMany large mining operations around the world have one or more semi-autogenous (SAG) mills doing bulk of the work in their size reduction operation. The SAG mill is usually followed by a ball mill to finish the size reduction prior to the concentration step. In the past when primary, secondary and tertiary crushers fed material directly to large ball mills, the energy efficiency of the concentrator was determined for the most part by the ball mill operation, whereas now the energy efficiency of a plant often rests largely on the SAG mill operation. As a result mines have shifted their emphasis in optimization from ball mills to SAG mill"

Jan 1, 2005

By Michael Drozd

"The operation of an activated charcoal system has five separate unit operations. These unit operations have common points for CIP, CIL and CIS system, which vary widely in application.The unit operations are:a. Absorptionb. Desorption (Stripping)c. Acid Washingd. Reactivatione. Carbon Handling (carbon transportation, sizing, dewatering, etc.)Cost optimization starts with the basic operating parameters (design philosophy) set down at the time of engineering design. These parameters undergo almost immediate change due to site specific ore requirements, throughput changes, operator requirements or reagent availability.Activated charcoal is sometimes viewed as simple, uncomplicated reagent that requires not optimization. To some extent, this statement is true, but under most circumstances, if the time necessary to optimize the use of activated charcoal is available, the effort is rewarded with significant savings. CPL-Carbon Link has embarked upon a program of supplying technical support with its activated charcoal. Several operations in the United States have undertaken to have CPL-Carbon Link do an operational survey to determine if potential savings are possible. CPL-Carbon Link has offered to do these surveys for projects that are clients or simply would like to have CPL-Carbon Link review their operation. The information accumulated by CPLCarbon Link is being used to attempt to fashion industry standards so that a common reference point can be established for activated charcoal usage."

Jan 1, 2008

By Peter Wells, Laxman M. Amaratuga, Todd M. Kanhai

"Certain mining methods (eg. Cut-and-fill) result in the contamination of run-of-mine ore with shotcrete. This shotcrete remains mixed with the ore throughout processing. Experimentation performed by Falconbridge Limited revealed that underground contamination of ore by shotcrete (eg. as little as 1% by weight) has led to ill-effects on the nickel recoveries from the flotation process in the mill. The nickel recoveries of contaminated samples were lower than tests without the shotcrete Contamination.To optimize flotation circuits it is important to know why the contamination has created these effects and also to find a method to abate or remove them. Laboratory testing showed that the age of the shotcrete was a factor in it’s effect on nickel recoveries. Younger aged shotcrete gave nickel recoveries lower than baseline nickel recoveries with no contamination. Older shotcrete gave nickel recoveries similar to the baseline.Literature on other cementitious material contaminations on ore revealed that a possible means of remediating this problem is the use of acid in the flotation. The initial pH in the flotation pulp was designed to be pH 9.2, but with the young shotcrete contamination the pH was in the neighbourhood of 10.5. Acid addition may act as a means of lowering the pH to the optimal operational value. Laboratory test work showed that acid addition brought nickel recoveries closer to the baseline."

Jan 1, 2000