Desulphurization of Placer Dome’s Musselwhite mine gold cyanidation tailings

Mill tailings with a potential to generate acid mine drainage should be properly disposed of to avoid environmental problems. Acid may be produced in a tailings site through reactions such as the following:
2FeS2 + 71/2 O2 + H2O Æ Fe2(SO4)3 + H2SO4
Fe2(SO4)3 + 6H2O Æ 2Fe(OH)3 + 3H2SO4
Although bacterial activity is known to promote the process, the principal requirement for these reactions to occur is the exposure of the sulphide mineral to oxygen and moisture. Thus, the placement of an inert cover over previously deposited tailings could provide sufficient protection from these agents and inhibit acid generation. The inert material needed for this purpose might be derived from production tailings by sufficiently reducing their sulphur content, i.e. by desulphurizing them, most probably through flotation. The suitability of desulphurized tailings as a cover material may be assessed by determining their net neutralization potential (NNP), which is the neutralization potential (NP) minus the acid generation potential (AP) of the tailings, all expressed in terms of tonnes of CaCO3/1000 tonnes of tailings. Any positive NNP value would theoretically imply that the tailings would be non-acid generating, but in practice higher values should be aimed at to be more certain.
Placer Dome Canada operates a 4000 tpd gold cyanidation facility at Musselwhite mine, in northwestern Ontario, where the mill tailings have been classified as acid generating due to their higher than acceptable pyrite (FeS2) and pyrrhotite (Fe8S9) content. Currently, the tailings are not desulphurized, but are treated for cyanide destruction using the INCO SO2/Air method prior to their disposal.
As part of the company’s tailings management program, a laboratory investigation was undertaken to examine the effectiveness of flotation in desulphurizing the tailings. Experiments were conducted, using the Box-Wilson experimental design method, to study the effect of pH, collector (KAX – potassium amyl xanthate) concentration, and air flow rate, and a computer simulation program was developed for the flotation process using Microsoft Excel and its Visual Basic Editor. Both the test data and simulation results indicated that the Musselwhite mine gold cyanidation tailings can be successfully desulphurized by froth flotation of the sulphide minerals contained in them. It was found that flotation could readily reduce the sulphur content of the tailings to well below 0.5% and raise their NNP values to 10 or more. The concentrate removal rate necessary to achieve these NNP levels would depend on the flotation conditions employed, however, according to the simulation assessments, it may amount to as low as 5% of the flotation feed. Among the process variables, the air flow rate proved to be the most critical, with pH and collector concentration showing lesser importance, as illustrated in the figure. It was therefore concluded that the amount of air admitted into the flotation cell needs to be carefully optimized and closely monitored in an actual plant operation. The use of copper sulphate for the purpose of reactivating the sulphide minerals was found unnecessary, and the reason for this has been attributed to the fact that copper sulphate is employed during the cyanide destruction process and thus reactivation might already have taken place at that stage. Pilot plant tests are presently underway at the mine site to further investigate the tailings desulphurization process in preparation for full-scale implementation.
Full Access to Technical Paper
PDF version for $20.00
Search
Sort By:  Relevance
Showing results 1 - 6
Text
Summary: This paper deals with specifying and evaluating fans for mine ventilation projects. Topics such as fan and equipment design life, operating points, and the operating conditions are discussed. Over the anticipated life of a mine’s ventilation system, the operating requirements will invariably change. Operating duties that define the range of the ventilation requirements need to be established. Apart from achieving planned operating pressure and volume range, consideration should be given to...
Publication: CIM Bulletin
Author(s): J.S. Stachulak, K.A. Mackinnon
Issue: 1084
Volume: 97
Year: 2004
Text
Summary: Gondwana coal deposits are widespread and are known to occur on four continents. Gondwana is the southern super continent that resulted from the breakup of the super continent Pangea during Late Carboniferous to Early Permian time. Gondwana was separated from the northern continent Laurasia by an equatorial sea, the Tethys. Gondwana coals are present in South America, Africa, India, and Australia. Laurasian coals occur in the United States, Canada, Russia, and Europe where they constitute the...
Publication: CIM Bulletin
Author(s): P.A. Hacquebard, M.P. Avery
Issue: 1084
Volume: 97
Year: 2004
Text
Summary: Minera Penmont’s La Herradura, which began in July 1998, is a joint venture between Industrias Peñoles, S.A. de C.V. and Newmont Mining Corporation. The mine is located in the northern Mexican state of Sonora. La Herradura consists of an open pit mine with a two-stage crushing plant and a heap leaching facility. Gold is recovered from the pregnant solution using the Merrill-Crowe process. La Herradura produces about 130 000 oz gold per year and its treatment capacity is approximately 22 000...
Publication: CIM Bulletin
Author(s): S. Cossio, J.-L. Noyola, P. González, R. Espinosa
Issue: 1084
Volume: 97
Year: 2004
Text
Summary: A number of fluidized bed applications in nickel extraction have been developed for commercial use. Five important processes have gained particular acceptance, namely, sulphide ore roasting, nickel sulphide (matte) roasting, nickel oxide reduction, laterite ore pre-reduction, and nickel chloride pyrohydrolysis. These applications all benefit from the fast reaction kinetics, high heat and mass transfer rates, and the excellent controllability of fluidized bed reactors. This paper examines the...
Publication: CIM Bulletin
Author(s): K. Adham, C. Lee
Issue: 1084
Volume: 97
Year: 2004
Text
Summary: Industrial practice in mineral processing shows that an important problem in understanding and monitoring in-mill parameters is due to the lack of fundamental knowledge and appropriate sensors. However, over the last decade, DEM modelling has shown an interesting potential in describing the fundamentals of grinding mill behaviour, in improving the understanding of internal grinding mill dynamics, and in developing solutions to industrial practice. With the objective of bringing this emerging...
Publication: CIM Bulletin
Author(s): P. Radziszewski, S. Caron
Issue: 1084
Volume: 97
Year: 2004
Text
Summary: Borehole seismic field tests were conducted over two sub-economic massive sulphide deposits located in Norman West, Ontario, and Halfmile Lake, New Brunswick, to assess the usefulness of this technique for the exploration of base metal deposits. The field tests were conducted by the Downhole Seismic Imaging (DSI) consortium, a consortium initiated by the Geological Survey of Canada, Canadian mining and services companies (Falconbridge, Inco, Quantec Geoscience, and Noranda), and universities...
Publication: CIM Bulletin
Author(s): G. Bellefleur, C. Müller, D. Snyder, G. Perron, E. Adam, K. Stevens, L. Matthews
Issue: 1084
Volume: 97
Year: 2004
Powered by Coveo Enterprise Search