Activox®

LOW TEMPURATURE AND PRESSURE OXIDATIVE LEACHING

• Pressure Oxidative Leaching
• What is Activox Process?
• Capabilities for Activox®  Leaching
• Activox® and Associated Testwork
• References

PRESSURE OXIDATIVE LEACHING

Pressure oxidative leaching (POX) is a well established technology which is used for processing base metal sulphides (eg nickel, copper and zinc) and for treating refractory gold ores and concentrates.

• Conventional pressure oxidation operates at temperatures exceeding 200ºC with overpressures of 2200 kPa or more. The technology is robust and reaction rates are fast.
• Activox is a form of pressure oxidation which operates at milder conditions of temperature and pressure; e.g. 95 – 100ºC and 1000 kPa. The milder operating conditions simplify the engineering requirements and reduce costs, yet maintain the advantages of pressure oxidation.

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What is the Activox® Process?

The Activox® process was first tested in 1991 and since that time, extensive testing has been conducted resulting in the further development of the technology. One of the major developments was the successful application of Activox® to the leaching of chalcopyrite concentrates.

Activox® is essentially a simple, yet novel approach to pressure oxidation. The process combines fine milling (using a suitable power-efficient stirred mill) with low temperature pressure oxidation. Control of the pulp chemistry is important to optimize metal dissolution, break down sulphides, achieve selectivity and minimize oxygen consumption. The process has been described in a number of publications.

SGS Minerals Services has made a major commitment to provide a “one-stop-shop” for clients who wish to evaluate the use of Activox® technology, from preliminary batch testing to fully integrated continuous pilot testing including cyanidation, solvent extraction and electrowinning as well as data interpretation, preliminary costing, engineering and feasibility studies.

SGS Minerals Services is able to back-up all Activox® testing with the services of our metallurgical laboratory and we are also able to evaluate alternative technologies like conventional pressure oxidation, bacterial oxidation and roasting.

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CAPABILITIES FOR ACTIVOX® LEACHING

Our capabilities for providing Activox® testing include:

• Fine milling carried out using vertical stirred mills
• Pressure leaching on a batch basis, using titanium autoclaves
• Pressure leaching on a continuous basis can be tested using our state-of-the-art pressure autoclave pilot plant. This is a fully integrated facility consisting of feed control, four-stage autoclave (25 L), neutralization, CCD circuit and downstream mixing/holding tanks. The plant is well instrumented for control and data logging purposes. The autoclave section has been specially designed to give accurate mass and heat balances and is extremely versatile with respect to testing various parameters like temperature profiles, retention times, oxygen flows, etc.

SGS Minerals Services has a wide range of other equipment, operated by experienced staff, to provide support to Activox® test programs, eg:

• Feed preparation – crushing, milling, sampling etc
• Concentrates production – flotation (batch and continuous pilot), gravity and magnetic separation
• Cyanide leaching - batch and continuous
• Solid/liquid separation - settling and filtration, batch and continuous
• Solvent extraction – batch and continuous mini-plant facilities
• Electrowinning – small scale to large scale, both batch and continuous.  A full-sized nickel cathode test facility has been operated.

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ACTIVOX® AND ASSOCIATED TESTWORK

• Batch leaching of a large range of concentrates has been carried out since 1992. SGS Minerals Services has built up valuable experience on how to optimize the oxidation and leaching of various sulphide minerals, including those containing copper, nickel, cobalt, zinc, arsenic and gold
• Continuous pilot testing including leaching, neutralization, CCD, precipitation, solvent extraction and electrowinning has been carried out on a number of nickel/copper/cobalt ores
• Solvent extraction programs, both batch and continuous, have been carried out on copper, nickel and cobalt using various circuit designs and reagents

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REFERENCES

Angove J E, Corrans, I J and Johnson, G D, 1993. The Recovery of Nickel and Gold from Sulphide Concentrates, in Proceedings of the XVIII International Mineral Processing Congress, pp 1227-1231 (AusIMM:Sydney).

Corrans, I J, Angove, J E and Johnson, G D, 1995, The Treatment of Refractory Copper-Gold Ores using Activox® Processing, in Randol Gold Forum Perth '95 - Gold Metallaurgy & Environmental Management, pp 221-224 (Randol International Ltd:Perth).

Johnson, G, Corrans, Ian and Angove, J, 1993. The Activox® Process for Refractory Gold Ores, in Randol Gold Forum 1993 Proceedings, pp 183-188, (Randol International Ltd:Beaver Creek).

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