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Pressure leaching
Pressure leaching is a well established hydrometallurgical alternative for gold, nickel, PGE and base metal ores. SGS Minerals Services has been active in this area since 1985, developing flowsheets and running integrated pilot plants in support of bankable feasibility studies featuring pressure leaching. Many operating plants have been built based on our studies.
Batch pressure leaching capabilities are available at our South Africa, Australia, and Canadian laboratories while continuous pressure leaching capabilities for extended pilot operations are available in Canada and Australia. Both locations utilise multi-compartment “submarine” style pilot autoclaves in combination with integrated downstream unit processes to test complex integrated metallurgical flowsheets for bankable feasibility studies.
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Why choose SGS?
- proven track record with hydrometallurgical pressure leaching
- wide range of equipment to support lab, batch and pilot scale projects
- extensive experience dealing with many deposit types
- applied research background to develop new technologies in this field (e.g. the PLATSOL™ process) or adapt existing protocols to maximize grade, recovery or costs efficiencies
- reputation of being impartial and fair and thus able to conduct independent process reviews
- bankable reputation which means that our technical reports are accepted for financing purposes
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OPERATIONAL PARAMETERS, SGS MINERALS SERVICES' PILOT-SCALE AUTOCLAVES
|
Australia |
Canada |
| Commissioned |
2001 |
1992 |
| Design |
titanium, 5-stage submarine |
titanium, 6-stage submarine |
| Working Volume |
65-75 L |
25-35 L |
| Maximum Temperature |
290°C |
255-270ºC |
| Maximum Pressure |
9 MPa |
5 MPa |
| Feed rate |
20-50 kg/h |
6-12 kg/hr |
| Pre-heat |
Steam heat exchange |
Electric heat exchange |
| Pressure |
Control automatic |
Semi-automatic |
| Let Down |
Single pot continuous discharge of slurry at 100°C with control. |
Single pot intermittent discharge of slurry at 100ºC |
| Sample feed and measure parameters during leaching |
Yes, each compartment |
Yes, each compartment |
| Process Control |
Distributed control system,
Windows operator interface |
Bailey distributed control system |
| Data Export and Handling |
Access or Excel |
Access or Excel |
| Flowsheets supported |
HiPAL™ * |
POX, HPAL |
| Especially suitable for |
Generating products for market evaluation |
Projects with limited ore or if cost of shipping is a factor |
| * POX-suitable autoclaves also available at Australian facility |
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OVERVIEW OF AUTOCLAVE APPLICATIONS
- Acid and alkaline oxidation of refractory gold ores and concentrates
- Copper, zinc, nickel and/or cobalt concentrate leaching
- Nickel concentrate leaching
- Sulphide precipitation of Ni, Co
- Uranium ore leaching
- Graphite concentrate purification
- Arsenic ore leaching (caustic)
- Molybdenite concentrate leaching
- Scorodite precipitation
- Nickel, cobalt laterite leaching
- Jarosite stabilization
- Hematite precipitation
- Caustic leaching
- Polymetallic PGM leaching (PLATSOL™)
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PRESSURE OXIDATION FOR GOLD
When direct treatment with a cyanide solution results in low gold extraction, the ore is termed “refractory”. Gold encapsulated in a sulphide matrix can be readily recovered after a destructive oxidation treatment. After leaching and neutralization, cyanidation or CIL can recover the gold. Pressure leaching in autoclaves has been developed into a standard operating procedure and is being applied in many operating mines. Test work is performed in the laboratory or in a continuous pilot plant operation.
Since the inception of pressure leaching for refractory gold ore twenty-five years ago, numerous operations have applied this technology, establishing it as a viable and robust process. Examples of the application of this technology are available worldwide.
Clients Include
Barrick Gold Corporation, Kinross, Nerco, International Corona, Polymet Mining, Ashanti Goldfields Company Ltd., TVX Gold Inc., Placer Dome Inc., Gold Reserve, General Gold.
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PRESSURE LEACHING FOR BASE METAL SULPHIDES
Confidence in pressure oxidation technology further spurred base metal (Cu,Zn,Ni,Pb) producers to consider a hydrometallurgical route for base metal recovery, particularly from complex sulphide ore systems. A number of process options are available for hydrometallurgical treatment of these ores, but pressure leaching is a common starting point.
SGS Minerals Services has experience with all the pressure leaching processes that have been developed for the treatment of base metal sulphide ores and concentrates.
Low pressure
- Activox Process
- MIM/Mt. Albion Process
Medium pressure
- Dynatec Process
- Anglo American/UBC Process
- Oxiana/Mt. Gordon Process
High pressure
- Phelps Dodge-Placer Dome Process
- PLATSOL Process
Clients Include
WMC, Codelco, Phelps Dodge Corporation, Exxon Mobil Coal and Minerals Company, Cyprus, Aker Kaeverner, SNC Lavalin, Fluor Daniel Wright, Oxiana, Polymet Mining
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PRESSURE LEACHING FOR NICKEL IN LATERITES
Recently, there has been considerable interest and development in the pressure acid leach (PAL) process as applied to the treatment of nickel laterites. SGS Minerals Services boasts the most comprehensive laterite processing test facilities in the world in both Canada and Australia. A number of major pilot plants have been operated to test a variety of integrated flowsheets, producing intermediate or final LME grade metal products.
Clients Include
BHP-Billiton, WMC, Weda Bay, Centaur Mining and Exploration Ltd., Preston Resources, CVRD, Ravensthorpe Nickel Ltd., Anaconda Nickel Corporation, Highlands Pacific Ltd.
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PRESSURE LEACHING FOR PLATINUM GROUP ELEMENTS
The application of pressure oxidation for PGM recovery from base metal sulphide concentrates has attracted much interest in recent years, as markets for these materials have increased. We have worked with a number of clients in the development of the PLATSOL™ process. This unique approach to simultaneous extraction of PGM group metals and the host base metals from complex sulphide orebodies is an excellent example of the in-house expertise held by SGS Minerals Services in this area.
PLATSOL™ is a single step, high temperature pressure leaching processing which the base metals sulphides are oxidized with oxygen to soluble metal sulphate complexes and sulphuric acid while the gold and the PGM are solubilized as chloro-complexes by the addition a small amount of chloride to the autoclave feed.
PLATSOL™ is especially desirable for the treatment of:
- Lean concentrates containing mixed base metals with relatively low concentrations of precious metals.
- Dirty concentrates containing deleterious elements
- High chromium and magnesium bearing concentrates
- Gold concentrates in areas where cyanide is prohibited
- Concentrates in areas here the resource base is small or the cost to transport concentrate or ore from a remote location to a smelter is prohibitive
Clients Include
Amplats, Lonmin Ltd.,Impala Platinum Ltd., Polymet Mining Corporation, Lac des Iles Mines, Stillwater Mining Company, BHP-Billiton, CVRD, Harmony Mines.
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For more information, please contact our Pressure Leaching Experts.
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