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Papers by Jacques McMullen

L’utilisation de remblai en pâte constitué de rejets de concentrateur pour le remblayage des chan... more L’utilisation de remblai en pâte constitué de rejets de concentrateur pour le remblayage des chantiers souterrains est une pratique de plus en plus répandue dans l’industrie minière. Une technique analogue peut aussi servir pour l’entreposage de ces résidus en surface. Puisque les résidus en pâte possèdent une densité et une résistance mécanique plus élevées que les résidus conventionnels, leur utilisation aide à réduire l’aire finale du parc à résidus miniers. Cette technique permet aussi d’augmenter le volume d’eau qui est récupérée au concentrateur. De plus, le remblai en pâte retient plus efficacement l’eau interstitielle en conditions non saturées, diminuant ainsi le risque de désaturation et le potentiel de génération de drainage minier acide (DMA). Présentement, le stockage des rejets de concentrateur en surface sous forme de remblai en pâte est limité à un nombre restreint d’opérations minières dans le monde. La mine Bulyanhulu (Tanzanie) de la compagnie Barrick Gold Corpora...

onto carbonaceous matter from preg-

La presente invention concerne un procede de recuperation de metaux precieux dans lequel des jaro... more La presente invention concerne un procede de recuperation de metaux precieux dans lequel des jarosites et/ou des sulfates ferriques basiques sont regules par le durcissement a chaud de la suspension epaisse de decharge de l'autoclave suivi de la decomposition de l'argentojarosite en utilisant des agents consommant des acides forts.

IFAC Proceedings Volumes, 2000

The evolution of automation and process control has forever changed the way gold processing plant... more The evolution of automation and process control has forever changed the way gold processing plants are operated. Over the past twenty years, from being fully manual, plants are, nowadays, virtually operating on full automatic mode. An overview of the process control evolution is presented along with the challenges currently faced which, when resolved, will allow turning to reality the future vision proposed on how plants are likely to operate.

$Research paper thumbnail of Procede de recuperation d'or et d'argent a partir de minerais refractaires$

Mining, Metallurgy & Exploration, 2003

$Research paper thumbnail of Process for recovering gold and silver from refractory ores$

ABSTRACT Underground,disposal of mine ,tailings as a ,paste backfill is becoming ,the state-of-th... more ABSTRACT Underground,disposal of mine ,tailings as a ,paste backfill is becoming ,the state-of-the-art in many,mining operations. Densified tailings are also a ,promising ,solution for surface storage. Since paste tailings have a higher density and strength than conventional tailings, their use for surface disposal may help decrease the final size of the land area covered by the impoundment.,It also increases the amount of water being re-circulated at the process plant. Moreover, because of its propensity to retain water under unsaturated conditions, paste tailings are less likely to be exposed to an oxidizing environment, which reduces the potential for generation of acid mine - 2 - drainage (AMD). Presently, storage of paste tailings on the surface is limited to a very small number,of mining ,operations around ,the world. Barrick’s Bulyanhulu Mine in Tanzania ,is considered to be a pioneer,of this technology. This paper presents some of the developments,on this approach, and discu...

Minerals Engineering, 1994

Gold thiourea complex adsorbs easily onto activated carbon, but elution fi'om the carbon is diffi... more Gold thiourea complex adsorbs easily onto activated carbon, but elution fi'om the carbon is difficult. Several elution colutitiot~ and eluants have been studied, such as organic acidic thiourea solutions at ambient temperature, alkaline thiourea solution, alkaline cyanide solution, sodium sulphide and sodium thiosulphate solutions at an elevated temperature range. Effects of variables, such as the concentrations of solution constituents, retention time and solution temperature etc., were investigated. The elution rate constant and the activity of the eluted carbon were used to compare the merits of the processes. The results demonstrated that organic thiourea can elute the gold thiourea complex fi'om carbon at ambient or low temperatures. At an elevated temperature range, alkaline thiourea and sodium sulphide solutions are more e~ciency. The best eluted carbon assays less than O. 2 mg Au/g C.

Minerals Engineering, 2005

Kalgoorlie Consolidated Gold Mines (KCGM), the largest gold producer in Australia, has spent in t... more Kalgoorlie Consolidated Gold Mines (KCGM), the largest gold producer in Australia, has spent in the last 4 years considerable efforts to develop a parallel processing alternative to roasting primarily because of the increasing sulphide content of the ore in the Superpit and the long term tendency for more stringent environmental regulations. Ultra-fine grinding (UFG) was the technology selected to process part of the increased concentrate tonnage. A laboratory investigation was then initiated, to improve the leaching conditions of the flotation concentrate with the objective of maximizing gold recovery while minimizing processing costs. The concentrate used for the laboratory investigation had the following composition: 41.4 g/t Au, 59.7% pyrite, 0.3% chalcopyrite, 38.2% gangue, and a P 80 of 114 lm. The gold in the concentrate is refractory and contains free gold, gold tellurides and gold associated with pyrite. Deslime concentrate and the ultra-fine grind fraction of the concentrate were also used in the study. A high concentration of lime in conjunction with lead nitrate proved more effective to dissolve gold tellurides compared to pH 11 used by the plant. The new leaching conditions also reduced significantly cyanide consumption from 12-15 kg/t to 3.5-4.0 kg/t. At a P 80 of 21 lm, the cyanidation with 4.5 g/L NaCN, 25 ppm DO, 1 g/L lime yielded solid residues with 8.6 g/t Au. Addition of lead nitrate to the leach produced a leach residue at 7.8 g/t Au. Using a finer grind, a P 80 of 11 lm, an additional gold extraction of 1.6 g/t was obtained, which was similar to the gold extraction of the UFG processed on site (leach residue of Gidji). The reduction of cyanide consumed was attributed to passivation of pyrite and chalcopyrite. Scanning Electron Microscopy (SEM) examination of the leach residue indicated that the majority of remaining gold was primarily encapsulated within pyrite; indicating that the refractoriness of the tellurides has been effectively mitigated by the approach. The high oxygen demand of the conditioning stage was reduced by adding lead nitrate. The leaching of the sulphide concentrate at a coarser grind is not an economical option. Lead nitrate addition showed a more beneficial effect on the leaching of UFG than leaching of the bulk concentrate. A plant trial on the effect of high lime concentration and lead nitrate addition, as well as a pilot plant trial, are scheduled to test the laboratory results.

International Journal of Mineral Processing, 1996

Percolation leaching with a thiourea solution was investigated for processing a low-grade gold su... more Percolation leaching with a thiourea solution was investigated for processing a low-grade gold sulphide deposit (Bousquet V) belonging to the mining company Lac Minerals Ltd. Certain leaching parameters, such as percolation rate, thiourea concentration, oxidizing agent (H ,O,, Fe3+) and granulometry were studied. To limit the phenomena of thiourea decomposition and to optimize gold extraction, it was necessary to maintain the leaching potential between 420 mV and 450 mV (S.H.E.). The maximum gold extraction in leaching the Bousquet V ore, after 75 days, varied b'etween 76% (H,O,) and 83% (Fe3'>, with thiourea consumption depended on the Tu/oxidizing agent concentration ratio and the nature of the oxidizing agent used. Acid consumption varied with ore granulometry (100 kg/t for-9.54 mm/+ 1.63 mm; 80 kg/t for-19.04 mm/ + 1.63 mm).