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By Norman M. P. Low

"IntroductionIndustrial applications of mica utilize two commercially important varieties of mica: muscovite and phlogopite. Muscovite mica is a potassium mica with a general chemical formula, H2KA1(Si04)3 h, and is sometimes referred to as a potas hsilicate. Phlogopite is a magnesium mica having a general chemical formula, H2KMgSi(Si04)3, and is distinguished from the muscovite mica by its decomposition in sulphuric acid.Canada is one of the major natural mica producers in the world. A large tonnage of the mica powders is at present mined and processed in the Eastern Townships of Quebec. This Canadian mica is of the phlogopite type. A closely related mineral of the mica family which is widely used in the construction industry is vermiculite. It is a dehydrated magnesium-aluminum-iron silicate characterized by a foliated structure. Expanded vermiculite, which is often referred to as exfoliated mica, is used as many types of thermal and acoustic insulation, as loose fill in buildings, as an aggregate in concrete, as an ingredient in plaster and insulating concrete , and in fire-proofing compositions. Natural phlogopite and muscovite mica powders are used extensively as reinforcing agents in organic polymers. They also have a wide range of applications in commerical products. For example, dry-ground mica powders are used in large tonnage as a surface finish in roofing materials and as a bonding agent in wallboard joint cement. Common products such as paint, rubber, plastics and welding rods contain mica. Recent studies have also shown that mica powders can be added to portland cement in the preparation of concrete products, as they could improve the tensile strength of the concrete products. The potential and possible"

Jan 1, 1982

By L. C. Bird, A. I. A. Salama, M. W. Mikhail

"A program of sampling in Canadian washeries was carried out by the Coal Research Laboratory (CRL) over a period of two years to evaluate the performance of various density separators in these operations(1). Operating data on quality and recovery of products, separation efficiencies and cutpoints for each separator type are compared with data predicted using computer models developed from previously existing data.The Heavy Medium Cyclone (HMC), Heavy Medium Bath (HMB) and jig models give predictions of recoveries and qualities of products for sizes coarser than 10mm with absolute value of error mean less than 7 per cent, whereas predictions of the Water Only Cyclone (WOC) model for -10mmfine coal are with absolute value of error mean less than 8 per cent. Although less accurate for -10 mm fine coal, the HMC and jig models produce predictions of recoveries with absolute value of error mean less than 2 per cent and quality of products predictions with absolute value of error mean less than 28per cent which are generally acceptable because more liberation in the fine fractions appears to compensate for any difference in the accuracy of separation, resulting in good prediction of the clean product. However, ash content of the actual fine refuse was lower than predicted. The difference is attributed to the highly friable nature of Canadian coals which tends to cause an excessive loss of coal fines to the fine refuse.A comparison study based on quality and recovery of products is made between the Dutch State Mines (DSM) models and the recently modified models, both produced comparable predictions."

Jan 1, 1985

By Libao Zhu, David J. Williams, Nazife Erarslan

"Statistics show that the drawbell in underground mines is usually subjected to significant damage by impact loading due to falling ore. Drawbell damage causes a large quantity of residual ore to remain on the drawbell, thus leading to a huge waste of ore resources. In this study, the Cavity Monitoring System (CMS) and Surpac software were employed to visualize the 3-D damage. Also, the Discrete Element Method (DEM) was employed to perform simulations of the falling ore to investigate the damage evolution of drawbells under repeated ore impact and obtain the dynamic damage accumulation mechanism. The reason of drawbell damage was found due to the micro-shear cracks. The numerical simulations of a drawbell damage process under repeated impact loading showed the main failure type was shear failure and this type damage was found increasing with more ore falling. INTRODUCTIONDrawbells are an important part of underground mines and play a significant role in ore recovery in terms of safety, economy and efficiency (Brunton et al., 2010; Hustrulid & Bullock, 2001; Trueman et al., 2002). In most cases, blasted ore is gravitated along the drawbell and finally arrives at the footwall of the drawpoint. However, some of the blasted oversize ore blocks clog the drawbell road and those ore pieces are called hang ups (Penswick, 1997). However, any damage on a drawbell is believed to be the reason for these hang-ups. In the literature, researchers have reported that the stability of the draw-point is influenced by the stress distribution above and near the drawbell (Butcher, 1999; Neverov & Neverov, 2013). Much research in the literature has been done on draw-points in underground mines. In fact, rockfalls cause very serious damage on a small impact area in a very short time (Volkwein et al., 2011). Hoek (2000) pointed out that the blasted ore causes progressive ravelling and even collapse of the drawpoint, thus the ore in the stope is abandoned. In this paper, the Cavity Monitoring System (CMS) was employed to obtain the damage profile of a drawbell due to the impact of rockfalls and to confirm the residual blocking ore on the damaged drawbell. Then, the drawbell damage evolution due to repeated falling ore was simulated by the Discrete Element Method (DEM)."

Jan 1, 2015

By H. Hejny

Given the current status of political discussion in Europe about raw materials issues, the sustainable development of the extractive industry and the reduction of its environmental and societal footprint are among the key topics in this discussion. In this context, the European Commission approved the EO-MINERS project (Earth Observation for Monitoring and Observing Environmental and Societal Impacts of Mineral Resources Exploration and Exploitation). The overall aim of EO-MINERS is to bring into play EO-based methods and tools to facilitate and improve interaction between the mineral extractive industry, authorities, and the society in view of its sustainable development while improving its societal acceptability. Developing generic, standardised and reliable EO-based products to monitor the environmental and societal footprint of mining projects is the way chosen by EO-MINERS to improve this interaction, along with the organisation of tripartite meetings gathering all relevant stakeholders. The project uses existing EO knowledge and carries out new developments on three demonstration sites (Sokolov lignite mining area, Czech Republic, Witbank coal field, South Africa, Makmal gold mine, Kyrgyzstan) to further evaluate and demonstrate the capabilities of integrated EObased methods and tools in monitoring the environmental and societal footprints of the extractive industry during all phases of a mining project, from the exploration to the exploitation and closure stages. It contributes providing reliable and objective information about affected ecosystems, populations and societies, to serve as a basis for a sound ?trialogue? between corporate stakeholders, governmental organisations and societal stakeholders. The project already developed a set of consolidated indicators based upon previous knowledge about mining-related issues along with interviews of national, regional, and local stakeholders. These indicators reflect known environmental and societal issues at mining sites as well as the interest of various relevant stakeholder groups. The process described in the EO-MINERS project ? policy assessment > indicator identification > choice of suitable EO tools able to serve monitoring task > monitoring by EO tools > making available objective information for fair dialogue among stakeholders ? is generally applicable to all stages of a mining project. The key to success will be the right choice of indicators addressing the problem and subsequently the right choice of suitable EO tools and finally the willingness of all stakeholders to find a common solution. To this end, the EO-MINERS project organises site-specific ?trialogue? workshops at each demonstrations site, which aim to provide relevant information in adequate quality to the stakeholders as common ground for discussions. Local stakeholders, including mining companies, regulatory bodies, and community representatives are invited to participate in these workshops where the relevance of the developed EO-based products to environmental and societal impact assessment will be discussed. The presentation will discuss results obtained during these trialogue workshops, as well as the success and difficulties and reluctances encountered. The project will further indicate ways and means how the EO products and other project results may be used for monitoring purposes in all phases of a mine.

Aug 1, 2013

By Edgar L. Horner

"The objectives of the Wabush Mines tailings stabilization program are to control dust Ii/t-off and to rehabilitate the disposal area. The evolution of the program started with test plots in 1970, these being continued and expanded upon through 1974. In 1976, a 35-acre vegetation field trial was attempted and failed, part of the failure being attributed to lack of adequate equipment. Subsequently, equipment was purchased and during the summer of 1979-80 extensive areas were treated. The program was also expanded to include the evaluation of chemical and water spray stabilization versus vegetation in areas where shorter-term control is required. In addition, during the summers of 1979-80, spruce bog material was spread over about 100 acres and seeded.The approach to reclamation by vegetation at Wabush is one of soil building. Work to this point indicates that iron ore tailings can be converted to a soil capable of supporting plants. Plans for the Wabush tailings disposal area should make dust lift-off from inactive tailings areas negligible within the next few years."

Jan 1, 1981

By A. Mular, T. Bond, G. D. Farnell, J. F. Kingston

"ABSTRACT:-A 60—cm semiautogenous grinding-(SAG) mill was designed -for continuous wet operation in closed circuit with a vibrating screen. The circuit is fully instrumented and automated. Part of the control system incorporates Foxboro SPEC 200 controllers around the pump box to maintain level. The rest of the control system involves an ACTION model BC2 basic direct digital controller that handles all other inputs/outputs and contact closure sensing:·The success of the control system is attributed to the uniqueness of specially designed mass flow metering systems. Various control strategies are possible. Employed to date has been control of a mill load set-point by cascading the deviation from load set-point as the set-point to the fresh feed rate ""controller"". Mill feed water is ratioed to total flow rate of solids fed to the mill. The performance of the circuit is being correlated with the performance of full scale SAG circuits in British Columbia to develop models, to assess the feasibility of scale up and to investigate the effects of design variables on responses such as circuit throughput. 1 INTRODUCTIONWhere ore types are appropriate, semiautogenous grinding and/or autogenous grinding (AG) has replaced conventional grinding. Secondary/Tertiary crushing plants are thereby eliminated so that capital expenditures are less and overall comminution costs can be lower (Barratt 1982). To establish the suitability of an ore for SAG circuits, pilot scale tests with 1.7 to 1.8 M diameter mills are often conducted. At least one test per ore type in a deposit has been necessary. Often, each test involves a large amount (up to 50 tonne) of sample, so that the testwork can be expensive and may discourage the use of SAG or AG circuits. However, MacPherson (1977) has employed a continuous 45 cm dry Aerofall mill circuit closed with screens and an air classifier to determine whether ores are suitable for SAG milling. The amount of sample per ore type is of the order of 60 kg or less. Thus an established SAG mill scale up procedure that employs small circuits is highly desirable.The purpose of this paper is to describe a small 60 cm wet continuous SAG/ AG mill pilot circuit assembled at the University of British Columbia to study the feasibility of scale up, to assess the influence of design variables, to develop mathematical models and to evaluate the effects of alternative control strategies on circuit performance"

Jan 1, 1988

By K. Tsuchihashi, A. Kishimoto, T. Uda, Y. Kado, S. Maruyama

We recently proposed a continuous production process for titanium metal with some experimental results. In the process, titanium tetrachloride is reduced by Mg in the presences of Bi to form a Bi-Ti alloy at 900ºC. At this temperature, the obtained alloy is liquid and allows for the continuous removal of product and heat from the reaction vessel. The obtained Bi-Ti alloy was vacuum-distilled at 1000ºC for 24 hr, and 98 at % (92 wt %) titanium, which was easily crashed to powder, was obtained. Bi solvent was selected because of the highest titanium solubility at 900ºC and the moderate vapor pressure among the candidate metals (Bi, Sn, Pb, Zn, and Sb).

Jan 1, 2014

By G. Simard, D. Boudeville, A. Leclerc, A. Boivin

"The objective of this work is to study the various parameters that affect the overflow clarity of gravity settlers used in the precipitation circuit of alumina hydrate from the Bayer process. A mathematical model incorporating the size distribution of the feed suspension (Multi Size Group model), its diphasic nature (Schiller Naumann model) and the presence of turbulence (Shear Stress Transport model) has been solved numerically using ANSYS-CFX software. Preliminary results indicate that the overflow clarity is mainly controlled by lateral diffusion of fine particles (~20µm) from the exit of the feed well and by their upward transport from the sediment bed interface. Also the turbulence pattern in the settling zone seems to play a significant role in this vertical transportation. The validity of the model has been verified by comparing the measured solid concentrations from a pilot classifier with the calculated ones. This model could provide mineral processing plant operators and designers with a tool to optimize the configuration of classifiers with respect to the overflow clarity.INTRODUCTIONProblemIn the Bayer process, alumina hydrate precipitation from the saturated liquor is initiated in settler by adding crystallization seeds. Most of the precipitated alumina settles to the bottom of the tank while the liquor and the remaining alumina rise to the top, where they are removed at the overflow. Ideally the overflow clarity, which depends on the operational mode of the classifier, should be controlled within targeted limits."

Jan 1, 2016

By Philip M. J. Gray

"The real cost of conversion from ore to semi-fabricated non-ferrous metals has been increasing for many years. Consumer resistance and improved knowledge and techniques now available justify investment in revolutionary as well as evolutionary methods of extraction. Metallurgical factors in current practice which preordain high production costs are identified as: smelters' demand for clean minerals, use of processes with low intensity of working per unit of reactor volume, use of low-velocity reactions, use of long reactor retention times relative to the speed of reactions, dilution of values in solution and commitment to electric power as a source of energy.Six new types of flowsheet are proposed for processing from ore to metal, composed of steps which are economic to construct and maintain and making maximum direct use of fossil fuel and the energy content of minerals. The basic knowledge and technology for developing these flowsheets exists. It is very tentatively suggested that these routes might reduce the capital and production cost for conversion of ore to metal by 30-50%."

Jan 1, 1980

By Pierre Montrueil, Marcel St-Amant

Within the next few years, underground mobile equipment will be partially automated. Mining methods will integrate more and more automation. Such an evolution will be possible only if adequate underground communication systems are developed. This is expected due to the available competence in Canadian telecommunication, to the economic pressure on the Canadian mining industries for international competitiveness and to the social changes where a better working environment (i.e. less accidents) becomes a major concern. CCARM propose the concept of a Production Area Network for Automated Mobile Units called PANAMU as an intermediate size communication system. It can be implemented using mature present-day technology and it can be integrated in some mine wide communication systems. It can evolve so as to incorporate new technologies because of its modular concepts. In this paper, the communication requirements are estimated, the amtmptions are defined, the concepts of the PANAMU are presented and an over- view of its implementation is described. CCARM presents this article to the mining industry as a document for discussion.

Jan 1, 1994

"This paper discusses the use of risk assessment and risk management techniques within the Australian underground coal mining industry, within the context of geotechnical risk. The industry works within a pro-active, “enabling” legislative framework, where companies and management apply a range of risk assessment tools as part of their everyday management processes. Different geotechnical risk factors and approaches are reviewed, together with application examples – ranging from mine planning and design, operations, and accident investigations.A particularly powerful resource in each of the above stages of geotechnical management is the RISKGATE system. RISKGATE is an assembled “body of knowledge” structured under different topics across the Australian coal industry, of which three topic areas address rock mechanics issues for both the underground and surface mining sector. This paper will provide an overview of RISKGATE in the context of risk-based rock mechanics applications in underground coal mining."

Jan 1, 2015

By Kwang-Hyun Jeon

Recently, 3D printing technology in the manufacturing field is in the spotlight. In the construction industry, similar rapid prototyping technology that does not use conventional form can be applied to meet the demand on free formed structure that can provide aesthetic value and functionality. Conventional formwork can increase construction cost and period for various structure with complex shapes while it has numerous advantages such as high strength, convenience, accuracy and good quality of surface roughness. To meet the demand on free formed structure, automated freeform construction systems such as Contour Crafting and Concrete Printing have been developed with active collaboration between university and industry in USA and England. However, details on the system have not been fully released in public, so the possibility of its fusion and spin-off technology cannot be expected. In this paper, cost-effective solution for mechanical and control system for constructing a free curved structure without mold are described. As an appropriate material for the system, fiber reinforced mortar was selected by experiments on compressive strength, setting time and fluidity. After performing G-code simulation, transfer and extrusion experiments with the selected mortar mix were performed and the possibility of the development of automated freeform construction system was demonstrated. Based on this research results, it is required to keep the automated freeform construction system improve and extend it into the new application area in construction industry.

Aug 1, 2013

By Bill Charbonneau

Lumen, lm The measurement unit of light emitted by a light source 60W incandescent840 lumens 32W T8 linear fluorescent3200 lumens 54W T5HO linear fluorescent5000 lumens 400W metal halide24,000 lumens

Oct 1, 2010

By Frank Martonhegyi

"The objective of this paper is to review the coal basins in the Canadian part of the Western Cordillera to aid their understanding, and to aid in finding and proving places of economic coal mining potential. Coal occurs in eugeosynclinal basins in the Western Cordillera which evolved through three stages: -from systems of volcanic arcs in the Late Jurassic to mid-Cretaceous; -through an intermediate stage with deposition in increasingly restricted successor basins in Jurassic to Early Tertiary; -to a continental stage by the Eocene. Minor coal seams occur usually in late volcanic arc stage sediments bur they can be locally thick as they are on Queen Charlotte Islands. Successor basins usually show a marine-paralic-limnic evolurion. Signijicanr coal deposits occur in the tarter two sequences in the Whirehorse (Tantalus) and Bowser (SkeenaSusrur) basins. Currenr activities are intensive in the more accessible Bowser Basin, for example at Telkwa, Susrut River and on the Groundhog coal field. On Vancouver Island major coal seams occur in cyclic sediments, but the more accessible deposits are mined our. Exploration renewed recently in the less accessible northern part of the Island, for example Quinsam, for surface mineable coal. The Western Cordillera is a mosaic of allochtonous tectonic blocks. They originated from the south and were displaced northward by several hundred kilometres. Many Tertiary coal basins are related to strikeslip transcurrent faults along which the later part of displacement took place, for example the Dawson coal area in the Tintina Trench. Tensional and dipslip normal faulting also created or enhanced sites for thick peat accumulation. For example at Hat Creek 280 m of coal occur in a 550 m section. Secondary structures are often better exploration targets than the main fault zones. Pluvial and alluvial fan environments away from the main drainage are usually the favourable sites for thicker and cleaner coal deposition."

Jan 1, 1985

By Bo R. Arvidson

"New permanent magnetic alloys have recently opened up possibilities for development of unique mineral separators. These are now making several new applications feasible. In many cases where conventional electromagnetic-induced roll separators have traditionally been used, the new permanent magnetic roll separators may reduce both over-all capital costs and operation costs.The development of the next generation of extremely powerful permanent magnets, i.e. neodymium-iron alloys, is progressing rapidly and will affect the roll separator as well as another type of magnetic separator. Permanent Magnet Roll SeparatorDesign and FeaturesDiscs of permanent magnets interleaved with soft iron discs constitute the basic magnetic roll design (Fig. I). By enveloping the magnetic roll with a thin abrasive resistant belt (Fig. 2), even highly magnetic particles are removed.The first prototype roll utilizing the new magnets was shown to have approximately equal strength as induced magnetic roll (IMR) separators. Since the initial test roll, the new separator, called the PERMROLL® , has been made twice as strong with regard to magnetic force, that is, the magnetic flux density is determined to exceed 1.7 tesla (17 kilogauss), while the magnetic field gradient is more than twice the gradient than can be practically achieved with IMR."

Jan 1, 1985

By Eiichiro Mizushima

Catalyst systems comprising (Ph3P)AuCH3 and acid co-catalysts were found to be highly efficient for hydration of alkynes to give ketones. Methanol was the best choice of solvents. Introduction Hydration of carbon-carbon unsaturated bonds is one of the environmentally benign routes to the carbon-oxygen bond formation. Hydration of alkynes forming carbonyl compounds, an important variation in this category, is a well known reaction which has been extensively studied. The reaction by acid-catalysis is the most conventional method, while it is applicable only to electron rich acetylenes to obtain satisfactory yields (1,2). The hydration of simple alkynes usually requires another catalyst (co-catalyst), typically a mercury(II) salt (3), which is inconsistent with the guiding principle of Green Chemistry (4).

Oct 1, 2003

By R. E. Stewart

"Using the concept of economic life and marginal analysis, it can be shown that proper equipment replacement timing can save a mining company many thousands of dollars. To assist management with determining the economic life of mining equipment, a new computer package has been developed. The package, called ERG (equipment replacement guide), incorporates all important economic factors related to equipment usage, such as operating costs, maintenance costs, salvage values, depreciation, volume of work, tax credits, inflation rates, ROJ, etc. The information is used in a series of equations which balance the costs of new equipment against the total cost of old equipment. The solution of the equations determines economic life and the point in time when the old equipment should be replaced. IntroductionIn an operating mine, equipment must eventually be replaced or downgraded for a variety of reasons. Fleets of haul trucks, dozers and other major pieces of equipment deteriorate over time until the mounting costs of maintenance and repair force either a major overhaul or the ir replacement by new and more efficient pieces of equipment.The question of determining the best time to replace old equipment has been approached in many different ways. Various methods, ranging from operating experience, intuition and physical necessity to sophisticated computer models have been devised to help cope with equipment replacement decisions . The best of the se will incorporate the most important economic factors related to equipment usage, such as operating and maintenance costs, salvage values, depreciation, work delivered, the cost of capital, tax credits and, of course, the effects of inflation.Economic TheoryThe fundamentals of equipment replacement theory grew out of the interaction between economics, engineering and finance. The use of annual cost comparisons and rate-of return calculations were helpful in handling situations in which assets with different finite lives were being compared. Later developments bringing together the concept of economic life and marginal analysis helped provide additional refinements to the theory. Taylorui showed that the displacement of an aging asset with a similar, but newer, asset can be justified economically when the marginal cost of keeping the asset one more year exceeds the minimum uniform annual cost equivalent of the proposed replacement."

Jan 1, 1980

Particles for heap leaching in conventional circuits are prepared using Cone crushers. Cone crushers are used to crush the ore to the size range between 12-25 mm for heap leaching operations. Leaching from these relatively coarse particles occurs only at the surface and in subsurface regions, which are accessible from the surface by cracks and pores. Since leaching is active in accessible areas, the method of comminution that forms multiple cracks and pores would offer an advantage for heap leach. An investigation was performed in this study to assess if the HPGR forms more cracks and pores than a Cone crusher. X-ray computed tomography (CT) was used to characterize the degree of cracks and pores formed by these two comminution devices that can be used for heap leaching feed preparation. In order to compare the effect of the comminution method on crack network generation, a bulk sample of the zinc ore was crushed by the HPGR at three different pressure settings (45, 95 and 120 bar), the sample ore was also crushed with a Cone crusher for comparison purposes. Products from the Cone crusher and HPGR experiment were then screened into five size fractions ((-25 +19), (-19+16), (-16+9.5), (-9.5+5), (-5+4.75) mm), Subsamples from the ((-25 +19), (-16+9.5), (-5+4.75) mm) size fractions were analysed. The spatial distribution of the crack network of sphalerite particles was characterized using a highresolution industrial X-ray CT system. This paper describes the use of image analysis techniques including image segmentation, which uses a combination of thresholding and other methods to characterize and quantify crack and mineral dissemination in the sphalerite particles after comminution with the HPGR and Cone crusher. The results are validated with those obtained using traditional techniques such as physical gas (with N2) adsorption, mercury intrusion porosimetry, SEM and QEMSCAN.

Jan 1, 2012

By K. J. Aglias, M. Jeffery, J. V. Simmons, J. A. Johnston, S. G. Fityus

"Shales and mudrocks undergo weathering in the near-surface geological environment, and degradation when directly exposed at the surface. Despite having superficially similar appearances, many shales have very different degradation behaviours. For example, some shales break down readily upon exposure whilst others remain more or less intact. Further, for those shales which break down, the style of degradation can vary greatly. A phenomenon is described where fresh shale blocks that are exposed at the surface undergo rapid breakdown to a fragmented texture which then persists for relatively long times, without further breakdown to finer soil particles. This is illustrated for some coal mine waste rocks. Furthermore, this metastable fragmented texture seems to be particular to each particular type of shale. The paper presents a conceptual model for this physical breakdown of shales which accounts for the differences in fragmental texture that are observed. The importance of several factors including strength, permeability and expansive clay content are identified for their contribution to the degradation behaviour of different shales.INTRODUCTIONShales and MudrocksThe term shale is applied widely to a class of mudrocks having a range of distinctive but gradational appearances and mechanical behaviours. Mudrocks are sedimentary rocks primarily composed of silt and clay sized particles (Tucker 1982). Mudrocks form in low to very low energy environments such as flood plains, lakes and deltaic environments, where the finest detrital particles are able to settle out of suspension (Reeves et al., 2006; Stow, 2005; Tucker, 2001).Unlike coarser siliciclastic sedimentary rocks, mudrocks do not present with a wide variety of sedimentary structures and textures. The most common texture is a preferred orientation of clays and micas parallel to the bedding plane. This textural component is related to the property of fissility or the ability for such textured mudrocks to split along smooth planes that are parallel to the bedding. Another common structure is lamination, formed by variations of grain sizes and types during deposition, Massive texture describes the situation where no sedimentary structures or textures are apparent (Boggs Jr., 2009; Tucker, 2001). The term shale varies between sources and contexts, with Reeves et al. (2006) stating that a shale is a fissile mudrock, where “fissility is a property that has developed at a certain stage of weathering”."

Jan 1, 2015

By K. van Netten, T. P. Ernst

"Froth flotation has been used successfully for about a century in the beneficiation of both coal and mineral particles. With the on-going trend towards lower feed grades, however, there is a need to transform this technology in ways that can deliver ultrafast separations, with strong selectivity, and recovery, covering a broader size range. It should be recognised that the hydrophobic effect, with its highly selective and long-range interactions, will most likely underpin any new technology. We identified the separation of the concentrate from the tailings as the rate determining step of conventional flotation technology. This limitation was then addressed by developing a novel flotation technology, insuring the formation of a concentrate that could be separated more rapidly from the tailings. We introduced a novel binder medium, a highly concentrated water in oil emulsion, to act as the focal point for hydrophobic adhesion, effectively replacing the air bubbles used in conventional flotation. The hydrophobic particles adhere to and become embedded within the binder, forming saturated agglomerates that float upwards. Moreover, by forming these large and resilient agglomerates, the product can be quickly dewatered over a screen and separated almost immediately from the tailings. Remarkably, this new binder permits residence times in the order of a few seconds under batch conditions. This paper examines the performance of the technology as a function of the oil wt% added to the slurry. The paper also examines the performance of the technology as a function of the particle size, showing a decline as the particle size exceeds 0.50 mm.INTRODUCTIONFroth flotation involves the collision and adhesion of hydrophobic particles to rising air bubbles, the carrying of those particles from the bubbly-pulp zone into a froth zone, and subsequent drainage and migration of the pulp to achieve the final concentrate (Wills, 2006). Within a Jameson Cell the feed slurry and air bubbles are brought into intense contact within the active area of the downcomer, achieving rapid kinetics of hydrophobic particle adhesion to the air bubbles (Harbort et al., 1994). However, once the bubble laden product and tailings emerge from the downcomer there is the need for separation of the concentrate from the tailings, an inherently slower process. In other devices such as mechanical cells the initial kinetics of particle adhesion are far slower, relying on the turbulent eddies throughout the cell, while in a column the kinetics rely upon an even slower process of bubble interception with suspended and settling particles (Gorain, 2007). However, in all cases the driving force for segregating the bubbles from the tailings, and the drainage of the froth are inherently the same. We do note, however, recent advances by Galvin and co-workers in achieving so-called Fast Flotation, utilizing a system of inclined channels to dramatically increase the segregation rate of bubbles from the tailings, permitting much higher gas and feed fluxes to be applied, achieving up to a ten-fold throughput advantage (Dickinson et al., 2014). Any further improvement within the existing flotation paradigm would require the introduction of centrifugal forces, but this would also require the formation of much finer bubbles than is typically used given the tendency of relatively large bubbles to reach a limiting slip velocity due to deformations and increased drag. Across all flotation devices we argue the rate determining step remains the segregation of the bubbles from the tailings."

Jan 1, 2016