Oxygen uptake rate test methodology

Oxygen is required during gold cyanidation for its dissolution and, at considerable mass input, for the oxidation of sulphide minerals if beneficial for the gold recovery process. Oxygen uptake rate (OUR) values for specific ores form important base data for further computations towards sizing the oxygen plant on a mine site.

Existing methods were reviewed, and the in-house procedure adapted to use the approach regarded as most valid. A series of testwork was performed to identify the test-specific parameters most liable to influence the produced data point. A flotation concentrate and two Run Off Mine (ROM) ores were used in the programme. The test data shows that grind (10-fold), temperature (a limiting factor due to intense oxygen uptake) and shear impact (+ 50%) are dominant factors, able to change the OUR value by factors. This would require more careful definition and application during tests. Sample ageing, often cited as a major concern, appeared to be of much less impact than anticipated.