Andrew Carter 
Technical Director
Tetra Tech - Coffey Geotechnics
EUR ING, CEng, BSc, MIMMM, MSAIMM, SME
Andrew is a practical operations and engineering manager with broad experience in base and precious metals - extractive, pyro-metallurgical and hydrometallurgical practice - acquired in nearly 40 years of operations line management, engineering and consulting practice. He also has a demonstrated track record in corporate financing and restructuring, business start-up and organisation building, technological innovation and problem solving, intellectual property management and patenting, project development and project management, environmental permitting, and business development and marketing. Andrew has worked on numerous projects throughout the world in countries such as Australia, Brazil, Bulgaria, Canada, Chile, China, Ghana, India, Peru, Russia, Sierra Leone, South Africa, USA, Zambia, and Zimbabwe.
The “Goldilox” Process For The Treatment Of Pyritic Gold Tailings
It is generally recognized that a large proportion of the gold remaining in the residues from most of metallurgical plants is occluded in pyrite. The conventional flotation-roasting process typically recovers approximately 40 per cent of this gold. The process described here is an unconventional route involving bacterial oxidation, which can achieve a gold recovery of approximately 80 per cent. The paper describes tests carried out in the laboratory, as well as on a slimes dam. The results show that the recovery of gold can be noticeably enhanced through the use of bacteria under conditions of controlled pH, moisture, and aeration. Biological oxidation of the pyrite releases the occluded gold, which then becomes amenable to cyanidation.