BACTERIAL LEACHING

SGS MINERALS SERVICES

Bacterial leaching is an established method of treating refractory gold and base metal ores or concentrates. SGS Minerals Services has undertaken testing for numerous projects for flowsheet development and optimization including bench scale and pilot plant testing, and audits and troubleshooting at operating plants in South Africa, Brazil, Ghana, Australia, Uzbekistan, Peru, Chile, Greece and the USA.

SGS Minerals Services’ services include:

• Research and development
• Amenability testing
• Flowsheet development
• Continuous pilot plants with integrated downstream processing
• Plant audits and troubleshooting

We have been requested by clients to establish bacterial leaching testing facilities to fulfill a need for:

• An independent testing facility not associated with any processing or engineering interests
• A “one-stop-shop” providing facilities to test alternative oxidation processes including, bacteria, pressure oxidation, Activox® and roasting

Technologies tested include:

• BIOX®
• GEOCOAT®
• (Heap or thin layer leaching of low grade flotation concentrates)
• BacTech processes
• Other non-propriety technologies

SGS’s expertise with the BIOX® process (mesophyllic bacteria) spans amenability testing to plant commissioning. Current research includes pilot testing of chalcopyrite-chalcocite-covellite concentrates using mesophilic bacteria.

We use GEOCOAT® processes in heap leach simulation, column leach testing of various sulphide minerals including pyrite, enargite and sphalerite using mesophile and extreme thermophile bacteria.  We are licensed to use the BacTech technologies and have completed several projects as indicated. Our current research focuses on investigating the oxidation of chalcopyrite.

Agglomeration Leaching of Concentrates
SGS Minerals Services Australia has developed a technique for heap or thin layer leaching of low-grade flotation concentrates. A binding agent is used to attach milled concentrates to the surface of an inert carrier. A suitable carrier is competent crushed rock such as granite in the size range 10 - 12 mm. The agglomerate is stacked in a column and treated by percolation leaching to oxidize the sulphide minerals. This technique may be applicable to low grade concentrates where agitated bacterial leaching or pressure leaching would not be economical.