Process development by Dynatec for the Ambatovy Nickel Project

The Ambatovy Nickel Project involves the proposed recovery of nickel and cobalt from a laterite deposit in Madagascar. The project has the potential to produce 60,000 t of nickel and 5,600 t of cobalt annually. In support of the bankable feasibility study, laboratory and mini pilot plant testwork was carried out at the Dynatec laboratory in Fort Saskatchewan. This paper describes the major findings of the test program.The Ambatovy ore is primarily ferralite (limonite). Saprolite is present at the base of the deposit and a transition zone, referred to as low magnesium saprolite, has also been defined. Separate bulk samples of ferralite and ferralite/saprolite blend were prepared for the testwork; the blend contained 1.29% Ni, 0.11% Co, 3.11% Al, 1.81% Cr, 46.2% Fe, 1.03% Mg, 0.83% Mn, and 2.53% Si.The preferred process includes acid pressure leaching, neutralization of excess acid with limestone, recovery of the soluble nickel and cobalt values as mixed sulphide intermediate by precipitation with hydrogen sulphide, and subsequent refining of the mixed sulphide to nickel and cobalt metals. Pressure vessels are used for the ore leach and sulphide precipitation steps. A Dynatec mini pilot plant autoclave, in operation during the Ambatovy ore leach testwork, is shown in the figure. The operating volume of this autoclave is about 30 L, corresponding to a scale-up factor of about 20 000 : 1 in comparison with commercial ore leach autoclaves.The mini pilot plant program included a 13-day unit operations campaign to test the ore leach and neutralization steps. The sulphide precipitation conditions were established in separate unit operations campaigns. Based on the results of the unit operations campaigns, a 9-day continuous process demonstration campaign of the ore leach circuit was then carried out, followed by a 6-day continuous demonstration of the sulphide precipitation circuit, using product liquor from the 9-day campaign.The Ambatovy ore responded very favourably to leaching. Nickel and cobalt extractions in the range of 95.5% to 97.0% and 94.0% to 97.0%, respectively, were achieved in the demonstration campaign. The optimal conditions in the ore leach step were sulphuric acid addition in the range of 220 to 300 kg/t of ore, 260°C, and a 75 min. retention time in the autoclave. The pressure leach discharge also proved to be amenable to a combination of slurry and solution neutralization with satisfactory rejection of impurities. The leach residue displayed excellent settling characteristics, both before and after neutralization with limestone, resulting in exceptionally good recoveries of metal values in the counter-current decantation wash circuit. Nickel and cobalt losses in the neutralization and washing steps were less than 1%.Approximately 99.5% of the nickel and 99.2% of the cobalt contained in the neutralized leach solution were recovered in the sulphide precipitation step, using relatively mild conditions of 105°C and 200 kPa H2S overpressure. The mixed sulphide product was then treated in a series of steps, simulating a commercial refinery, to ultimately produce separate nickel and cobalt metal products with better than acceptable purity.The successful testwork program has demonstrated a technically viable process for treatment of the Ambatovy ore and has provided essential data for the capital and operating cost study.
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Summary: Surface subsidence and sinkhole development over abandoned and collapsing underground mine workings are major environmental and public safety hazards in some areas. Small-scale undocumented workings are particularly problematic because their presence is often unknown until infrastructure has been developed over them and there is an unexpected subsidence event, often requiring expensive site stabilization or abandonment. Surface wave imaging is a relatively new seismic technique that generates...
Publication: CIM Bulletin
Author(s): S.D. Butt, C. Xu, M.D. Vance, G.C. Corbett
Issue: 1089
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Publication: CIM Bulletin
Author(s): P. Harvey
Issue: 1089
Volume: 98
Year: 2005
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Summary: Several sources of information often contribute to the comprehension of an ore deposit, for instance samples from diamond drill holes, reversed-circulation drill holes, or blast holes. Even if all the available information comes from the same drill hole type, it may have been collected through several campaigns, sampled with different protocols, or analyzed by different laboratories. In general, these sources of information do not have the same quality, therefore, they constitute different...
Publication: CIM Bulletin
Author(s): X. Emery, J.P. Bertini, J.M. Ortiz
Issue: 1089
Volume: 98
Year: 2005
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Publication: CIM Bulletin
Author(s): G. McIsaac
Issue: 1089
Volume: 98
Year: 2005
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Summary: Underground coal production at the Hustas mine, west of the village of Eynez, was from the KM2 seam, which lies at an average depth of 200 m and ranges from 15 m to 25 m in thickness with an average extractable thickness of about 18 m. The underground lignite mining methods employed in Turkey are mostly non-mechanized longwall methods. At the Hustas mine, the method used is a manual double-slice longwall method. The face area is maintained at about 2 m high using hydraulic steel props...
Publication: CIM Bulletin
Author(s): C.O. Aksoy
Issue: 1089
Volume: 98
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Summary: Load-haul-dump vehicles (LHDs) are extensively used in underground mining, however, equipment design and operating conditions contribute to restricted operator sight lines. The inability to clearly see people, objects, or hazards around the machine has contributed to a number of accidents including fatal injuries. In order to identify vehicle design characteristics resulting in restricted and blocked sightlines, line-of-sight assessments are traditionally completed in the field. However,...
Publication: CIM Bulletin
Author(s): T. Eger, A. Jeffkins, P. Dunn, I. Bhattacherya, M. Djivre
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Volume: 98
Year: 2005
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