Bioleaching technology, originally developed by BacTech Mining Corporation (re-named REBgold Corporation on December 2, 2010) employs the use of naturally occurring bacteria, harmless to both humans and the environment, to liberate precious and base metals from difficult to treat ores and concentrates. The registered trademark for REBgold’s bioleaching technology is “BACOX”.

Following completion of a Plan of Arrangement in December 2010, BacTech Environmental Corporation was granted a perpetual, exclusive licence by REBgold Corporation to use the BACOX technology for the remediation and reclamation of tailings left by previous mining operations.

The following provides some background on the technology and patent process.


The First Technology commercially developed by REBgold using the technology of Kings College London, relates to a process for recovering base and/or precious metals from sulphide materials comprising bacterial leaching the sulphide material with an aqueous solution at a temperature of 25°C to 55°C. The aqueous solution contains a thermotolerant bacterial culture which has an optimum growth temperature of 40°C to 45°C, and is capable of promoting oxidation at a temperature of 25°C to 55°C. The oxidized residue is separated from the aqueous liquid and metal is recovered from the residue and/or aqueous solution.

The Second Technology, purchased from VistaTech, relates to a process for recovering precious metals from particulate sulphide materials comprising bacterial leaching the sulphide material with an aqueous solution at a temperature of 45°C to 90°C. The aqueous solution contains a facultative or obligate thermopile capable or promoting the oxidation of the sulphide material. The oxidized residue is separated from the residue and/or aqueous solution. The bioleaching is carried out at a temperature of at least 45°C, and in the presence of nutrients to oxidize the mineral sulphide and liberate the precious metal. This technology relates mainly to the use of higher temperature bacteria which is more relevant for base metal extraction.

The First and Second Technologies are the subjects of patent applications and registrations in a number of countries as follows:

In Australia, the original patent application 652231 with respect to the First Technology was subject to an opposition by Billiton South Africa Limited (“Billiton”) and an opposition by Technological Resources Pty Ltd. The patent application was refused. The decision does not prevent REBgold from using its technology for gold or base metals. BacTech (Australia) Pty Ltd has filed a Divisional Application with respect to Application 652231. This has allowed REBgold to file more detailed data on the base metals applications within the Patent Application that the company believes are still patentable. The commercial application of the First Technology is dependent upon trade secrets and other proprietary information in addition to the patents.

REBgold and Mintek have jointly applied for patents for improvements to copper bioleaching in a number of Central and South American countries, including Mexico.

In addition, REBgold has access, through its agreement with Mintek, to technology for the bioleaching of chalcopyrite that has been patented in a number of countries and has applications pending in others.

More recently, REBgold has been granted patents in Chile and Spain for development of a novel reactor system and this has also been registered in the USA .

REBgold has also recently been granted patents for a method of improving heap leaching using high temperature bacteria in a number of South and Central American countries and in Namibia and South Africa.

Of equal or greater value to patents, is the knowledge that REBgold has gained from testing, piloting, and commercially applying the technology to a complete spectrum of sulphide ores and concentrates for precious and base metals. The company has adapted the bacteria to create a vast number of differing inoculums applicable to many ores and concentrates. This repository is an extremely valuable component of REBgold’s intellectual property, as it represents a significant barrier to entry for competitors. In addition, REBgold has developed detailed methods for utilizing the technologies. These methods are part of the intellectual property of REBgold, although the nature of the methods may be such that they would not substantiate the granting of a patent.