A study of the falcon concentrator

• Main Author: Buonvino, Mark
• Format: Others
• Language: en
• Published: McGill University 1993
• Subjects: Engineering - Metallurgy
• Online Access: http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=67457

A Falcon model B6 was tested on a massive gold-copper sulphide ore (AgnicoEagleLaRonde Division, AELR), to assess its ability to produce a smeltable concentrate(200000 to 300000 g/t); a fine gold-pyrite-silica flotation tail (Meston Resources, MR)to assess the Falcon's ability to recover gold from a low density and very fine material;and a synthetic magnetite-silica ore to obtain more fundamental information on its modeof operation.For 20 kg of AELR's flotation concentrate fed at 20 to 30% solids at 20-30 l/min,the Falcon recovered 22 ± 3% of the gold at a grade of 900 g/t. It overloaded whenmore than 20 kg of material was processed and recovery dropped sharply.Samples of MR's flotation tails were processed with the Falcon. Three differentbowls (8, 10, 14 degree) were tested at two flowrates (10,20 L/min), and three densities(10,20,30 %w/w). None of theparameters were found significant for pyrite, but bowlangle and flowrate were found to be significant for gold. On average, the Falconrecovered 50% of the gold and 20% of the pyrite at a concentrate grade of 4.0 g/t goldin a weight yield of 10%.Three 3-level nested factorial experiments were performed with an artificial feedconsisting of silica and magnetite to study the effect of gangue particle size, bowl type,% solids, and flowrate. A typical loading cycle includes (i) the initial unselectivecreation of a first concentrate bed; (ii) more selective recovery as bed growth stops and(iii) saturation of the bed surface leading to a zero incremental recovery .A sythetic feed (5% magnetite, p5% silica) was used to characterize the Falcon'sloading cycle, its overload, and the effect of operating variables. Overload with thesynthetic feed was virtually complete upon feeding 30 kg, either at 20 or 30 L/min.Three 3-level nested factorial experiments showed that for a constant mass of thesynthetic feed, magnetite recovery increased with decreasing particle size and bowl angle.These effects masked the impact of feed flowrat === Le separateur Falcon est un nouvel appareil centrifuge qui a ere concu pourrecuperer de l'or fin « 53ILm). Cette etude visait a mieux comprendre sonfonctionnement.Un concentre de flottation de la mine Agnico-Eagle, Division LaRonde (75%de pyrite, 200 g/t d'or) a ere traite avec un separateur Falcon afin de produire unconcentre fusionable (200000 a 300000 g/t). Pour une masse traitee de 20 kg, lemeilleur rendement (recuperation d'or: 22 ± 3%; teneur du concentre: 900 g/t) a eteatteint aune densite de 20 a30 l/min, et un debit de 20 a 30 l/min al'alimentation.On a note qu'en augmentant la masse de 20 a80 kilogrammes, la recuperation d'ora diminue de facon tres marquee.On a effectue une deuxieme serie d'essais avec un rejet de flottation tres finde la mine Meston (60% de silice, 1% de pyrite, 1 g/t d'or) afin de reduire les pertesd'or du circuit de flottation. En moyenne, le Falcon a pu recuperer 50% de l'or desrejets, dans un concentre de 4 g/t qui pourrait etre cyanure.Une derniere serie d'essai a ete completee avec une alimentation synthetique(95% de silice et 5% de magnetite) afin de preciser le fonctionnement du Falcon etd'identifier le lien entre la recuperation et les conditions d'operation. Le bol a l'anglele plus aigu, 8°, en presence de la gangue fine, -75 ILm, a permis de maximiser larecuperation de magnetite. Plus precisement, la recuperation de magnetite etait pluselevee pour les tailles granulometrique tres fines « 50 ILm), moyenne pour les taillesgrossieres (+ 200 JLm), et faible pour le reste.On a identifie 3 etapes qui caracterisent le cycle de fonctionnement duseparateur: i) au debut du cyle, l'accumulation de solides contre la paroi du bol, etla formation d'une couche de concentre; ii) une phase de recuperation selective a lasurface de la premiere couche du concentre; iii) et la saturation ala surface vers lafin du cycle. fr