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Design and measurement of small recovery gains / N.O. Lotter in Minerals engineering, Vol. 23 N° 7 (Juin 2010) 

Public ISBD [article]  in Minerals engineering > Vol. 23 N° 7 (Juin 2010) . - pp. 567–577 Titre : Design and measurement of small recovery gains : A case study at Raglan concentrator Type de document : texte imprimé Auteurs : N.O. Lotter, Auteur ; A. Di Feo, Auteur ; L.J. Kormos, Auteur Année de publication : 2011 Article en page(s) : pp. 567–577 Note générale : Génie Minier Langues : Anglais (eng) Mots-clés : Flotation  Xanthates  Plant  trial  Reference  distributions  Autocorrelation Résumé : The appearance of a significant amount of liberated fine pentlandite in the Raglan tailings, during a campaign to demonstrate future ore behaviour, called attention to a recovery opportunity. This opportunity was identified by a statistical benchmark survey of the operation during that campaign, and QEMSCAN measurement of these survey samples. This development was caused by escalating ore treatment rates and different characteristics in future ore sources. It was thus proposed to change the selection of collector from potassium amyl xanthate (PAX) to potassium isobutyl xanthate (PIBX). Laboratory scale flotation testwork, using high-confidence flotation testing, followed. The PIBX showed much faster flotation than the PAX. Nickel yield to first rougher concentrate was increased from 23.5% to 44.2%. The Raglan flowsheet bypasses this first rougher concentrate directly to final concentrate. Thus there was an expectation that overall performance would improve at plant scale when using PIBX. A designed plant trial was implemented in 2007 to measure and confirm the performance gain. This trial design used on–off switching following a 3-month baseline data block of normal operations using PAX. This layout provided checking of standard PAX performance prior to and during the trial. Thereafter, they were used to evaluate the trial blocks using PIBX. This trial format was deliberately designed so as to overcome the effects of autocorrelation in the operations data. In this way, small but significant metal recovery gains may be measured and proven in a plant trial. The paper describes the case study to show that this approach successfully blocks out autocorrelation in time, which is an obstacle in analysing concentrator operations data. The results showed that the PIBX had produced clear and statistically significant recovery gains for Ni, Cu, Pt and Pd. Adjusted for feed and concentrate grades, these recovery gains were: Ni: 1.04%, Cu: 1.01%, Pt: 2.67% and Pd: 1.79% in absolute terms. DEWEY : 622 ISSN : 0892-6875 En ligne : http://www.sciencedirect.com/science/article/pii/S0892687510000099 [article] Design and measurement of small recovery gains : A case study at Raglan concentrator [texte imprimé] / N.O. Lotter, Auteur ; A. Di Feo, Auteur ; L.J. Kormos, Auteur . - 2011 . - pp. 567–577. Génie Minier Langues : Anglais (eng) in Minerals engineering > Vol. 23 N° 7 (Juin 2010) . - pp. 567–577 Mots-clés : Flotation  Xanthates  Plant  trial  Reference  distributions  Autocorrelation Résumé : The appearance of a significant amount of liberated fine pentlandite in the Raglan tailings, during a campaign to demonstrate future ore behaviour, called attention to a recovery opportunity. This opportunity was identified by a statistical benchmark survey of the operation during that campaign, and QEMSCAN measurement of these survey samples. This development was caused by escalating ore treatment rates and different characteristics in future ore sources. It was thus proposed to change the selection of collector from potassium amyl xanthate (PAX) to potassium isobutyl xanthate (PIBX). Laboratory scale flotation testwork, using high-confidence flotation testing, followed. The PIBX showed much faster flotation than the PAX. Nickel yield to first rougher concentrate was increased from 23.5% to 44.2%. The Raglan flowsheet bypasses this first rougher concentrate directly to final concentrate. Thus there was an expectation that overall performance would improve at plant scale when using PIBX. A designed plant trial was implemented in 2007 to measure and confirm the performance gain. This trial design used on–off switching following a 3-month baseline data block of normal operations using PAX. This layout provided checking of standard PAX performance prior to and during the trial. Thereafter, they were used to evaluate the trial blocks using PIBX. This trial format was deliberately designed so as to overcome the effects of autocorrelation in the operations data. In this way, small but significant metal recovery gains may be measured and proven in a plant trial. The paper describes the case study to show that this approach successfully blocks out autocorrelation in time, which is an obstacle in analysing concentrator operations data. The results showed that the PIBX had produced clear and statistically significant recovery gains for Ni, Cu, Pt and Pd. Adjusted for feed and concentrate grades, these recovery gains were: Ni: 1.04%, Cu: 1.01%, Pt: 2.67% and Pd: 1.79% in absolute terms. DEWEY : 622 ISSN : 0892-6875 En ligne : http://www.sciencedirect.com/science/article/pii/S0892687510000099

The formulation and use of mixed collectors in sulphide flotation / N.O. Lotter in Minerals engineering, Vol. 23 N° 11-13 (Octobre 2010) 

Public ISBD [article]  in Minerals engineering > Vol. 23 N° 11-13 (Octobre 2010) . - pp. 945–951 Titre : The formulation and use of mixed collectors in sulphide flotation Type de document : texte imprimé Auteurs : N.O. Lotter, Auteur ; D. J. Bradshaw, Auteur Année de publication : 2011 Article en page(s) : pp. 945–951 Note générale : Génie Minier Langues : Anglais (eng) Mots-clés : Flotation  Mixed  collectors  Synergy Résumé : Mixtures of collectors have been widely used for many years in sulphide flotation, and a range of performance benefits have been reported for many different systems. The combinations of collector types have varied, as have the ratios that have been used. Synergistic effects have been obtained (greater than the sum of the parts) and in some cases the mechanisms of this improved behaviour have been identified. These benefits have been attributed to increased carrying capacity of the froth phase, faster kinetics, and more successful recovery of middling or coarse particles. It is the interaction between the various components of the mixed collector system, rather than the individual main effects, that dominate the performance benefits. The process benefits include increased paymetal recoveries and grades – as well as increased rates of recovery whilst using lower dosages of reagents. Various mechanisms have been reported and are discussed. These have been shown to affect different composition/liberation classes and sizes of mineral particles. In recent years, automated quantitative mineralogy and surface analysis technology such as ToF-SIMS have enabled the development of better information, to establish what aspect of the process has been affected. This has been successful mostly for use in a diagnostic capacity. Candidate selection for the mixed collector suite is presently based on experience and contextual knowledge. Predictive properties from these systems are a desirable future goal. Currently optimum combinations are preferably identified experimentally at laboratory scale prior to any plant trial. It is recommended that such laboratory work be performed using a factorial design with replicates and quality controls, such as may be delivered from High-Confidence Flotation Testing. The purpose of this paper is to summarise and review current theory and practice in the usage of mixtures of collectors in sulphide flotation – both in the application and in research in order to develop insights and guidelines to develop a methodology for use in a predictive capacity. A case study demonstrating this approach will be published at a later date. DEWEY : 622 ISSN : 0892-6875 En ligne : http://www.sciencedirect.com/science/article/pii/S0892687510000671 [article] The formulation and use of mixed collectors in sulphide flotation [texte imprimé] / N.O. Lotter, Auteur ; D. J. Bradshaw, Auteur . - 2011 . - pp. 945–951. Génie Minier Langues : Anglais (eng) in Minerals engineering > Vol. 23 N° 11-13 (Octobre 2010) . - pp. 945–951 Mots-clés : Flotation  Mixed  collectors  Synergy Résumé : Mixtures of collectors have been widely used for many years in sulphide flotation, and a range of performance benefits have been reported for many different systems. The combinations of collector types have varied, as have the ratios that have been used. Synergistic effects have been obtained (greater than the sum of the parts) and in some cases the mechanisms of this improved behaviour have been identified. These benefits have been attributed to increased carrying capacity of the froth phase, faster kinetics, and more successful recovery of middling or coarse particles. It is the interaction between the various components of the mixed collector system, rather than the individual main effects, that dominate the performance benefits. The process benefits include increased paymetal recoveries and grades – as well as increased rates of recovery whilst using lower dosages of reagents. Various mechanisms have been reported and are discussed. These have been shown to affect different composition/liberation classes and sizes of mineral particles. In recent years, automated quantitative mineralogy and surface analysis technology such as ToF-SIMS have enabled the development of better information, to establish what aspect of the process has been affected. This has been successful mostly for use in a diagnostic capacity. Candidate selection for the mixed collector suite is presently based on experience and contextual knowledge. Predictive properties from these systems are a desirable future goal. Currently optimum combinations are preferably identified experimentally at laboratory scale prior to any plant trial. It is recommended that such laboratory work be performed using a factorial design with replicates and quality controls, such as may be delivered from High-Confidence Flotation Testing. The purpose of this paper is to summarise and review current theory and practice in the usage of mixtures of collectors in sulphide flotation – both in the application and in research in order to develop insights and guidelines to develop a methodology for use in a predictive capacity. A case study demonstrating this approach will be published at a later date. DEWEY : 622 ISSN : 0892-6875 En ligne : http://www.sciencedirect.com/science/article/pii/S0892687510000671