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By Shuo Zhang, Wenying Liu

"In dump leaching, the efficiency of metal extraction from ores is strongly influenced by the mechanisms of fluid flow. Particle size distribution acts as a fundamental parameter in the determination of fluid flow properties in packed ore beds. In this study, we investigated the particle size distribution in dump leaching by using image analysis technique. The results showed that the particles in the dump varied from smaller than 2 cm to larger than 200 cm in diameter. P80 was calculated to be 200 cm, which was significantly higher than the historical data used by the operation. P25, P50 and P80 were found to increase non-linearly with increasing depth towards the toe of the dump, suggesting the segregation of fine and coarse particles. The image analysis results were verified by applying the rock fragmentation models. The model with the Swebrec function was found to be in better agreement with the image analysis results. Future research will investigate the effect of particle size distribution on the behaviour of fluid flow.INTRODUCTION Fluid flow plays an essential role in the extraction of valuable metals using heap/dump leaching (Amos et al., 2009). The rates of the chemical leaching reactions and microbial activities determine metal concentrations in the leachates and therefore the efficiency of the metal extraction. The reaction rates are influenced by two fundamental processes: transport phenomenon and reaction kinetics (Bouffard & Dixon, 2001). The transport phenomenon refers to the percolation of fluids through channels and pores in a packed ore bed, which carries lixiviants and reaction products to/from ore surfaces by convection and diffusion. The percolation rate of the leaching solution is determined by the hydraulic conductivity of the packed ore bed, which is a function of the permeability and the degree of saturation (Guzman et al., 2008). Permeability, an intrinsic property of a packed ore bed, is strongly influenced by the particle size distribution of the ore grains (Bouffard & Dixon, 2001). Hence, the objective of this study was to investigate the particle size distribution in dump leaching."

Jan 1, 2017

By Nelson Lawrence

An Electrical Risk Management/Inspection Program has been designed specifically for the mining sector in order to provide electrical code expertise and systemic gaps in electrical systems. Goals include improved safety and productivity, reduced injuries and help to enable businesses to better comply with the electrical codes and regulations that govern them. The Electrical Risk Management/Inspection Program is now recognized by some of the world?s largest mining organizations. Since June, 2001 these electrical safety advisory services have been available to underground and surface mine sites throughout Ontario and are now offered throughout Canada and around the globe. This program is also currently being applied to review new electrical installations for mine construction projects thus improving the safety and reliability of mine site electrical systems.

May 1, 2006

By Nicolas Gatelier, Sophie Laurent, Thierry You

Hard-rock caverns for hydrocarbon storage are a very particular type of underground facility controlled not only by local administrative and regulatory constraints that can be very specific, but also by the possible risks of geotechnical or geomechanical failure. Each such facility throughout the world is a prototype that needs to be adapted to very different site conditions. The straight forward application of design methodologies from relatively similar fields (mines, tunnels) can be very useful, but risks holding back the scientific and technical improvements needed by an engineering industry in full development. Here we look at various case histories and at problems that have been raised where recent attempts at standardization would appear to have been ill adapted, and where storage designers, through experience and judgment, may still provide innovative engineering solutions.

Jan 1, 2015

By R. L. J. Phillips

"The environmental impact of the Rabbit Lake project is presented. Baseline data for fish, water, air and radon collected in 1973, 1975, 1980and 1986, are compared with post-development environmental monitoring data. Predicted environmental impacts for the developed Rabbit Lake and B-zone deposits are compared to the actual impacts. INTRODUCTIONThe environmental impact of the Rabbit Lake project has been documented through the years in several submissions to the government agencies. In 1972, the environmental baseline study for the Rabbit Lake area was completed prior to any mining activity at the Rabbit Lake pit (Fig. 1).Sampling concentrated on Hidden Bay and Pow Bay, which received the treated effluent and the waters drained from Rabbit Lake respectively.A second baseline study was done on the Collins Bay area in 1980(Fig. I) in preparation for the mining of the B-zone pit. The detail in this study was considerably greater than the detail in the previous study. Collins Bay and Harrison Peninsula were the areas sampled. The B-zone deposit is being mined at present.With the discovery of the A-zone, D-zone and Eagle Point deposits, it was decided in 1986 to begin proceedings to obtain approval from Saskatchewan's Department of the Environment, and from the Atomic Energy Control Board to develop these deposits.In preparation, a third baseline study of both the Rabbit Lake and Collins Bay areas was done in 1986 and 1987. The emphasis was to establish the baseline at the three new deposits, to quantify the actual impacts of the existing Rabbit Lake operations and to confirm the Collins Bay B-zone (1980) impact predictions. The new deposits will allow us to continue to produce uranium into the future. In January 1988, Saskatchewan approval was received.Since 1975 in the Rabbit Lake area and 1980 in the Collins Bay area, routine environmental monitoring has been done. This has resulted in one of the largest and most comprehensive environmental data bases in North America in mining. By the time the Eagle Point deposit is mined to completion, there will have been data collected for approximately 40 years.Further discussions follow which describe the impacts of the past (1972 to 1984), the present (1985 to 1987) and the future. In addition, the past and present performances and the future plans of the .waste management systems will be discussed."

Jan 1, 1989

By David McMullen

Radiation plays a critical role in the thermal behaviour of hydrometallurgical process equipment. This effect is particularly important when designing refractory lined equipment used in pressure leach/oxidation processes. In order to simplify this non-linear mode of heat transfer, the effects of radiation had previously been incorporated in an equivalent convective film coefficient in finite element methods (FEM). This prior method omits the effects of radiosity, a critical aspect of radiation heat transfer, which affects the design of refractory lining systems in autoclave vessels. Given that 60% of the heat loss in actual plant practice of an autoclave is due to radiation, reliability in the FEM is therefore impacted. This study validates the use of radiosity in FEM through thermal loading using a combination of simple geometries to be applied to complex environments such as vessel nozzle clusters. The added benefits of using a radiosity load includes an increase in confidence in thermal distribution results, greater accuracy in determining appropriate refractory lining systems, weld overlay sizing, and increased accuracy in structural analysis.

Jan 1, 2014

By V Dolmage

In 1957 and 1958, ten topographically suitable damsites were investigated along the Peace river between Finlay Forks and Hudson Hope, B.C. Of these, three were eliminated after a reconnaissance survey indicated that the geology was unsuitable for the 650-ft.-high dam contemplated. ?After extensive drilling, five other sites were deemed unfeasible because of geological factors and, in 1959, the two remaining sites were designated as being suitable, one for the high dam and the other for a low dam downstream. The sites are located in the Peace River canyon, on the west and the south? side of Portage mountain, west of Hudson Hope. The site for the large dam, the Portage Mountain dam, has since been investigated by surface mapping, thousands of feet of diamond drilling, a seismic survey, laboratory rock tests and on-site grouting tests in order to establish the possible effect on the dam of all facets of the foundation rocks. Three diversion tunnels, 50 ft. in diameter and 2,200 feet in length, have been driven through massive sandstone and shale, and an intake cut, 500 ft. in length, 200 feet in width and 200 feet in depth, has also been excavated in rock.

Jan 1, 1963

By M. B. McClenaghan, O. P. Lavin, Ian Nichol

"Abstract-Exploration in most areas of Canada has to contend with problems posed by glacial overburden. In many areas exploration for gold has been based on the sampling of tills, frequently by deep overburden drilling, and analyses of heavy mineral concentrates. Notwithstanding the significant role that till geochemistry has played in the discovery of some important gold deposits over the last few years, increased appreciation of the nature of the glacial history and stratigraphy and the character of gold within till has led to the recognition of a number of ways whereby the effectiveness of exploration can be improved upon.In order for till geochemistry to be useful in exploration, a number of conditions must be fulfilled, including:1. mineralization, or alteration halo related to mineralization, subcropping at the bedrock /over­ burden interface; 2.glacial erosion and dispersal of a recognizable signature of mineralization into the glacialsediments; 3, preservation of glacial sediments containing this geochemical component (trace metal or mineral) at positions subsequently selected for sampling (normally drill sites); 4. correct identification of specific till units and associated ice movement history; 5. collection of adequately large and representative samples; 6. appropriate sample preparation and processing; 7, appropriate geochemical analyses; and 8. correct data processing and interpretation.While we have no control over the first two geological conditions, and only limited controlover till availability, we can control the quality and thoroughness of sampling, sample identification, sample preparation, analysis and interpretation. In particular attention needs to be focussed on obtaining a large enough sample to be adequately representative, an unbiased sample must be collected, together with appropriate sample processing, analysis, data processing and interpretation. It is considered that by modifying or extending existing approaches to gold exploration the chances of exploration success can be increased. In particular, analyses of both the heavy mineral and minus 63 ?m fractions of till is recommended because gold in till may occur in different size fractions."

Jan 1, 1992

By Roger T. Laine

"The Carswell structure, located in the western part of the Athabasca Basin, northern Saskatchewan, has been extensively explored since 1967. This exploration has been successful and lead to the discovery, in 1970, of the D sandstone-hosted unconformity related deposit. By the end of 1984, five additional basement-hosted unconformity related deposits had been delineated: the OP and N discovered in 1970, the Claude in 1971, the Dominique-Peter in 1981, and the Dominique-Janine in 1984. The D deposit has been mined out; the Claude open-pit has already produced more than 500 tonnes of uranium, the development of the Dominique-Peter underground mine (first phase) has been completed, and production from the latter started in 1985.All six deposits are located in the southern part of the Aphebian metamorphic core, 18 km in diameter, which has intruded at least 1250 metres of Helikian Athabasca Group sediments during a cryptoexplosion event at 480 Ma, unrelated to the emplacement of uranium mineralization. The metamorphic rocks, affected by the Hudsonian Orogeny, are divided in two lithostratrigraphic units: the Peter River gneiss, aluminous gneiss series, and the Earl River complex, mixed quartzofeldspathic and mafic gneiss series. A well developed regolith profile is recognizable in the south along the contact with the sandstone and inside the metamorphic core sometimes associated with conformable sandstone beds.Basement and sandstone-hosted uranium deposits show many similarities:-linkage to unconformity;-mineralogy and geochronology with a first phase mineralization characterized by a polymetallic sulphide-uraninite-brannerite assemblage dated at 1150 to 1050 Ma, a second phase characterized by a simple sulphide-uraninite assemblage dated at 890 to 820 Ma, and a third phase characterized by a pitchblende-hematite dated at 380 Ma; and,-linkage to early Hudsonian structures with remobilization of these structures during intense hydrothermal alteration resulting in Mg chlorite-illite halos."

Jan 1, 1986

By J. H. Crocket, J. Andy Fyon

"All gold deposits within the Tisdale Group are spatially associated with carbonate alteration zones; however, not all carbonate alteration zones are host to gold mineralization.Within the komatiitic and magnesium tholeiitic volcanic rocks at the base of the Tisdale Group, discordant and stratabound carbonate alteration zones occur throughout. The alteration zones consist of a ferroan dolomite - quartz inner assemblage which is enveloped by calcite-quartz and an outer chlorite-rich subzone. Factors which control the distribution of carbonate alteration include joint systems, flow contacts, synvolcanic faults and bulk composition of the host rock.Two environments of carbonate alteration can be recognized: 1) The subsea-floor alteration zones developed within the volcanic rock succession where hydrothermal fluids did not discharge directly onto the sea floor. Insignificant gold production has come from this alteration environment. 2) Seafloor zones, which represent points of hydrothermal fluid discharge into the hydrosphere, are spatially associated with felsic volcanic rock complexes and are host to syngenetic, auriferous cherty dolomite.Carbonatized, magnesium tholeiitic basalts, which are host to the auriferous, cherty dolomite, are enriched in antimony (>0.35 ppm), boron (>30 ppm), gold (>5 ppb) and lithium (> 35 ppm), but are depleted in copper ( < 70 ppm), with respect to carbonatized basalts not associated with gold. Orerelated, altered komatiitic flows can be screened using gold (>5 ppb), lead(> 10 ppm), arsenic(> 70 ppm) and antimony (>1 ppm).The habit, petrographic characteristics and certain geochemical characteristics of the altered volcanic rocks suggest that the hydrothermal fluid was of sea-water origin."

Jan 1, 1982

By C. E. Rodgers

WHEN I was asked to prepare, for presentation at the 1938 Annual Meeting of the Institute, some data concerning low-discharge grinding at the Sylvanite mill, it seemed entirely reasonable to expect to have at my disposal the results of at least four full months&apos; operation after the last unit, as then proposed, was installed. Delays in delivery of equipment, nevertheless, shortened the interval, as will be shown herein. In submitting the data contained in this discussion, I wish distinctly to state that the intention is not to claim that final conclusions can be reached at this time concerning our operation. Test periods, in certain instances at least, have been too short for this purpose, although some, where so stated, have been extended through March and April. It is hoped, however, that an advantageous trend in practice can be shown and that the experience related may be of interest to others who are now operating, or who are considering the operation of, low-discharge grinding mills. In the plant under review, four mills are in use: one primary and three secondary. Present mill capacity (grinding, as shown by screen test, about 99 per cent through-200-mesh and approximately 88 to 89 per cent minus-325-mesh with infrasizer giving about 90 per cent of the latter) averages about 525 tons per day. A brief description of each unit will be given and comments will also be made relating to operation. This will be followed by certain test data from which, in conclusion, operating results are summarized.

Jan 1, 1938

By T. W. Wloder

During recent studies concerning the effects that various surface treatments, surface imperfections, locked-in residual stresses and metallurgical and geometrical notches have upon the mechanical behaviour of metals and, in particular, upon their tension-bending characteristics under impact loads, it became apparent that specially developed methods and samples would be of great assistance in determining the desired data. This paper describes and discusses a number of different types of double-notched tension-bending impact samples which have been considered and examined for this purpose. The types most suitable for exploratory investigations are proposed for application in the study of the _behaviour of metals, their welds, and, in particular, their surfaces, when subjected to various notch-severities, surface imperfections, strain rates, temperatures, and constrained states of stress (i.e. the relations of the three principal stresses). It is expected that the proposed double-notched tension-bending samples and the proposed test methods will also contribute toward further understanding of the cold brittle behaviour and the notch-sensitivities of metals. The possibilities of introducing the so-called impact notch-sensitivity index and relative impact notch sensitivity of metals are discussed. Data obtained on double-

Jan 1, 1961

By A. A. Brant

Self-potential methods are based ?on measurements on the surface of voltage distributions caused by natural sub-surface oxidation phenomena. The attempt is made to. correlate voltage minima or maxima with the location of mineral materials or geological conditions which may give rise to such naturally produced spontaneous potentials. Any orebody undergoing oxidation is a source of electric current. Ground waters carrying free oxygen attack the upper surface of the body, rendering this the positive pole of a galvanic cell, with the lower portion of the body the negative pole and the surrounding weak acidic waters the electrolyte. Current flow is from positive to negative through the orebody and negative to positive through the electrolyte, i.e., through the surrounding rock. The upper end of a steeply dipping, tabular orebody is hence indicated as lying below the point on the surface where the largest negative potential is observed(l). From its basis, it is apparent that the self-potential method was developed primarily for ore exploration.

Jan 1, 1942

By R. D. Parker

Location The Frood ore-body is expressed on surface as a prominent gossan ridge, with a total length of approximately two miles. The original Frood (the old No. 3 mine of the Canadian Copper Company) is at the southwest end of this gossan; adjoining it on the northeast is the Frood Extension (until 1929 the property of i:he Mond Nickel Company), while at the extreme northeast end is the Stobie mine. The first two of these divisions of the ridge form the Frood mine as it is known today.? This lies in lots 6 and 7 of the sixth concession, township of McKim, and is two and a half miles north of the city of Sudbury. The general elevation is 1,000 feet above sea level. The Ore-Body The Frood-Stobie parallel offset(l), as its name implies, has no connection in the field with the main mass of the Sudbury nickel eruptive-a norite. It lies one mile to the southeast of that body, and, in general, parallels it in strike. The ore occurs as a more or less tabular structure in what is known locally as the Sudbury series. They are the oldest rocks of the district, and have been placed by Collins(2) as earlier than the lower Huronian, of pre-Cambrian time. The series is comprised of sediments, volcanics (both acid and basic flows), tuffs, agglomerates, breccias, and basic intrusives, all highly metamorphosed, yet all forming a more or less regular picture. The controlling feature of the area has been the attitude of the sedimentary strata, from which has arisen the present sill-like character of the flow rocks, the basic intrusives, and the ore-body itself.

Jan 1, 1932

By David Thomas, Charles Harper, Brian Watters

The Star-Waddy Lakes area lies withjn the northeasterly-trending early- to mjd-Proterozoic volcanoseilimentary-pl utoruc belt referred to as the La Range Domllin. In the area investigated the domajn is composed of the Central Metavolcaruc Belt which is bordered by metasedimentary belts of the Crew Lake and MacLean Lake Belts to the northwest and southeast respectively. The boundaries between the Central Metavolcanic Belt and the flanking belts are generally marked by prominent zones of shearing. The volcanosed imentary succession is intruded by a variety of ultramafic to felsic plutons which, on the basis of lithology, field relations and geochronology, can be broadly subdivided into three groups or episodes. These are: a) an 'early' (ea. 1866 Ma), possibly subvolcanic, episode marked by composite intrusions ranging from gabbro-diorite to granite, b) an 'intermediate' (ea. 1854 Ma) plutonic event distinguished by more homogeneous felsic intru ions ; and c) a 'later' (ea. 1835 Ma) event characterized by leucocratic quartz-rich grani te intrusions. The La Range Domain has undergone polyphase deformation with a strongly developed northeast-trending structural grain. Large scale folding is manjfested by large regional sy nforms, arcuate and triangular patterns associated with many of the plutons and by tight to isoclinal folds within the adjacent metasedimentary belts. Inhomogeneous strain characterizes much of the Star-Waddy Lakes area. With strain gradients being typically very steep, zones of high strain consisting of zones of extreme extensional fabrics, discrete shearing, as well as broader zones of cataclasis and structural slicing, are often juxtaposed with areas of relatively minimal deformation . Dilation structures tend to favour these zones of highly contrasting strain. Late, brittle fractures, faults and shear zones are widespread and appear to be particularly important as loci for gold mineralization. Metan1orphic mineral assemblages indicate that upper greenschist to middle amphibolite facies conditions were attained. Geological and geochenucal evidence indicates that the Central Metavolcanic Belt evolved in an island arc environment. Metavolcanic rocks from both the Waddy and Star Lakes areas display similar characteristics on variation diagrams (e.g. AFM and the Jensen cation plot) in that the dominant trend is calc-alkaline with some basic to intermediate types having a mildly tholeiitic character. A few samples from the southern end of Lower Waddy lake display komatiitic to basaltic-komatiitic afl'injties. The relatively immobile minor and trace elements (e.g. Ti , Zr, Nb, Y, Cr) provide reliable characterization of the metavolcanics, particularly of the basalts, which have highly distinctive trace element properties. Geochemical patterns for the basalts are similar to those for modem volcanic arc basalts. Low initial 87Sr/86Sr ratios (0.7017 - 0.7019) are consistent with a subduction-related origin for the volcanics. The major plutons have chemical properties typical of volcanic arc granites and are largely calc-alkaline in character, showing little chemical variation from the volcanics.

Jan 1, 1986

By A. A. Rogozhin, E. G. Likhnikevich, S. I. Anufrieva, A. V. Kurkov

The Beloziminskoe deposit in Siberia is a large, potentially productive deposit of rare metals contained in ochreous apatite pyrochlore ores formed by weathering of a carbonatite. The ores are composed of pyrochlore, columbitized pyrochlore, monazite, apatite, magnetite, ferric and manganese hydroxide, titanic iron ore, zircon, hydromica, quartz, feldspar, and carbonates. A gravity-flotation enrichment flowsheet with application of cationic and anionic collectors has been developed. This flowsheet allows for obtaining a pyrochlore concentrate containing 44.3% Nb2O5 and 1.89% P2O5 with recovery of 55.83% Nb2O5 as well as an apatite concentrate containing 39.2% P2O5 and 1.05% TR2O3 with recovery of 62% P2O5 and 43.23% TR2O3 from ores containing 0.92% Nb2O5, 16.9% P2O5 and 0.6% TR2O3. Rare-earth concentrate containing 40% TR2O3 with recovery of approximately 10% TR2O3 was obtained at the same time. Major losses of valuable elements are related to slimes, which make up more than 50% of the ground ore. The niobium concentrate does not meet the phosphorus and radionuclide concentrations needed for the production of ferro-niobium. Acid leaching and sulfatization provided a high level of phosphorous and radionuclide removal. Conditions include hydrochloric acid pre-leaching at 75- 80°C with an 18% HCl solution for four hours and low-temperature sulfatization of acid-leached concentrate at 160-180°C for one hour followed by water leaching of the residue. The apatite concentrate could potentially be processed using nitric acid leaching. This technology is based on decomposition of apatite concentrate with 55-57% strength nitric acid with transfer of rare-earth metals into solution in the form of ammonium phosphate. This technology recovers a rare-earth concentrate containing 95% TR2O3 with extraction of 86%, and highly concentrated polynutrient fertilizer (ammophos) with phosphorus extraction of 95%. The completed research shows how complex multicomponent ores of residual soil may be processed for the extraction of niobium, phosphorus, and rare-earth products.

Jan 1, 2016

By S. R. Izatt

The use of MRT, a highly selective separations technology, has long been demonstrated to be a cost effective, efficient, and environmentally sound process for extraction of a wide range of anions and cations that are commonly found in copper electro - refining and electro - winning circuits, as well as in environmental treatment operations. This paper provides an update of commercial MRT applications in the copper industry. Several recent installations and test programs are reviewed including recovery of bismuth from tank house electrolyte, and from chloride matrix selenium reduction solution which is generated in the anode slimes treatment process. Recovery and refining of platinum group metals originating in the anode slimes is also discussed. Various other base metal and other target separations of interest to the copper producer are also reviewed. The recovery products are high purity metal salts which can be marketed directly or readily reduced to metal.

Jan 1, 2007

By Beaumier. M., J. -P. Lalonde

"Les réultats obtenus dans les sols sur quatorze aires d&apos;essai et six cheminements régionaux dans I&apos;A bitibi-Témiscamingue indiquent clairement qu&apos;il existe des variations régionales importantes dans les teneurs en éléments traces de l&apos;horizon A1 formé sur l’épais recouvrement glacio-lacustre de cette région. Les anomalies obtenues correspondent à celles qui ont été décelées lors de précédents levés des eaux souterraines et du till de base.Selon les critères d&apos;évaluation utilisés, treize des quatorze aires d&apos;essai ressortent comme anomales dans Ie contexte abitibien; dix de celles-ci sont tres anomales. Ceci suggère fortement qu&apos;un levé régional de sols, fondé sur une approche multi-éléments, identifierait entre 70 et 90 % des cibles géochimiques reconnues par des échantillonnages en profondeur. Les résultats d&apos;un échantillonnage systématique effectué sur une région de 1000km2 viennent aussi appuyer cette hypothèse. Conséquemment, les sols formes sur les sédiments glacio-lacustres sont un médium très utile pour inventorier de grandes regions recouvertes par ce typ e de sédiments.L &apos;horizon A1 est Ie plus utile pour ce type de levé parce qu&apos;i1 est facil e d échantillonner, qu &apos;it assure une plus grande constance du typ e de matériel échantillonne et qu&apos;il contient des teneurs accrues.De multiples mécanismes de dispersion géochimique ont joué des rôles d &apos;importance variable pendant et après la mise en place des sédiments glacio-Iacustres. Les plus importants sont la pression hydrostatique, la diffusion chimique et électrochimique ainsi que la bio-accumulation. Si on veut progresser dans la connaissance de ce milieu complexe, on devra adopter une approche plus systemique tenant compte de I&apos;interaction des mécanismes agissant dans l&apos;environnement global avant, durant et apres Ie depôt du mort-terrain."

Jan 1, 1984

By M. Leroux, S. R. Rao, J. A. Finch

"Poor Pb-Zn selectivity during Pb flotation in laboratory tests on a Mississippi Valley-type Pb-Zn ore was traced to apH effect. In the pH range, 9.5 to 11.0 sphalerite floated readily without copper activation. Compared to sphalerite flotation with copper activation this procedure gave equivalent selectivity but reduced flotation rate.Possible mechanisms of this sphalerite flotation without copper activation are discussed. Activation by Fe(OH)2 is suggested, the Fe- + ions being derived from superficial oxidation of pyrite in the ore. IntroductionGalena and sphalerite commonly occur together. A typical procedure, using xanthate collectors, is to float the galena first, at pH - 8, followed by flotation of sphalerite after activation with copper (II) sulphate at pH - 10 (to depress pyrite).Flotation tests following this procedure in an undergraduate laboratory course with a Pb-Zn ore from Polaris failed to achieve consistent selective flotation of galena. Occasionally a considerable amount of sphalerite, even though unactivated with CUSO4, floated. This was traced to accidentally high pH. A systematic study was carried out which revealed that sphalerite floated readily in the pH range 9.5 to 11.0 without activation by CuSO4 This paper describes the results of the study and discusses a possible mechanism of this flotation of sphalerite."

Jan 1, 1987

By M. Laframboise, M. Buarzaiga

High-pressure acid leaching (HPAL) of nickel laterites has received considerable attention in recent years. High paymetals extraction, good selectivity, and advances in pressure hydrometallurgical technology are some of the reasons for this interest. Falconbridge Limited (Sudbury. Ontario) investigated the HPAL process using both fresh water and seawater for ore processing. The use of seawater resulted in a chloride concentration of 7.8 g/L in the autoclave feed. A test program was developed to study the effect of process water and leach temperature on the leaching behaviour of different ore compositions from the Koniambo deposit in New Caledonia. The work showed that salinity has a major effect on autoclave chemistry. This paper explores the results.

Jan 1, 2004

By Jean-Sébastien Kroll-Rabotin, Éric Climent, Florent Bourgeois

"Falcon concentrators are enhanced gravity separators designed for concentrating fine and ultrafine slurries. The Falcon UF model is unique in that it is dedicated to beneficiation of ultrafines, one key feature being that it does not make use of any fluidisation water. In a former study, we investigated the physical mechanisms that govern the transport of ultrafine particles (in the range 10 to 80 µm) inside Falcon UF concentrators, and concluded that separation efficiency is governed by differential settling. Initially, we derived and published a predictive model of the partition function under dilute conditions. The present paper proposes an extension of the initial model to concentrated ultrafine suspensions for application to industrial scenarios. The paper discusses how hindered settling has been added into the initial model to account for solid concentration effects. The modified model is tested against experiments carried out with a laboratory scale UF Falcon concentrator from dilute conditions up to 30 vol%. A good agreement between measurements and model predictions is obtained, which confirms that our hypotheses about the physics of separation inside a UF Falcon separator remain valid even at high concentrations.INTRODUCTIONThe Falcon concentrator is a fast spinning bowl that is fed at its centre of rotation. It uses centrifugal force to separate particles that are transported inside a thin liquid film that flows upward along the inclined wall of the bowl (McAlister and Armstrong, 1998). Due to differential settling, dense and coarse particles are concentrated inside the bowl whereas light and fine particles are rejected with the overflow stream. The fast rotation speed of the bowl yields high centrifugal force several hundred times the attraction of Earth. Despite the thinness of the liquid film (between 100 µm and 1 mm with a Falcon L40) where separation takes place, the Falcon concentrator can treat high flowrates (up to 30 L/min). At the bottom of the bowl, an impeller transmits the bowl rotation to the feed, which drains upward by centrifugal force as soon as it hits the base of the spinning bowl (Figure 1)."

Jan 1, 2011