In most instances, the application of high-chrome grinding media results in an increase in the recovery of the valuable mineral(s). The authors have published data from a number of plant-based case studies, which indicate that it is not unreasonable to expect a recovery increase in the vicinity of 1.5 to 2.0 per cent for a copper ore. It is of interest to understand where the increase in recovery is coming from. That is, is the additional copper recovery the result of improved fine particle flotation or is it due to an improvement across all size fractions?
This paper aims to answer this
question. Laboratory flotation tests were completed using forged steel and a
high-chrome alloy on a volcanogenic massive sulfide copper ore. The unsized data
indicated that the application of high-chrome grinding media to this ore
resulted in an improvement in both copper recovery and copper concentrate grade.
A detailed kinetic analysis of both the copper sulfide and gangue minerals was
completed that clearly shows that the change to a more inert grinding media
produced significant increases in the flotation rate constants (both fast and
slow) across all size fractions. It is also possible to observe that the change
in pulp chemistry has resulted in a decrease in the flotation kinetics of the
-20 micron pyrite, while the coarse pyrite recoveries have increased, presumably
because of an increase in the flotation of the chalcopyrite/pyrite composite particles.
Greet, C J, Jacques, S and Kinal,
J, 2014. Recovery-by-size kinetic analysis to determine where metallurgical
improvements occur when converting to high-chrome grinding media, in
Proceedings 12th AusIMM Mill Operators' Conference 2014 , pp 217–224 (The Australasian Institute of Mining and Metallurgy: Melbourne).