Since the early seventies high chro
mite and low base
metal sulphide (BMS) contents of the UG2 reef i
mposes technological challenges to
mineral processors and extractive
metallurgists. Forty years later, particle size distribution and size by size
mineralogy are considered as key factors to the continuous i
mprove
ment of the UG-2 ore
metallurgy. With the successful develop
ment of ultra fine grinding technologies, a co
mpro
mise has to be found between fine grinding to achieve platinu
m group
minerals liberation and to avoid the overgrinding of gangue
minerals, especially chro
mite gangue which is detri
mental in s
melting process. Indeed, fine chro
mite grains, despite of being naturally hydrophobic
mineral, can be recovered in flotation concentrate by entrain
ment. In addition, overgrinding also increase liberation of naturally floatable gangue (talc) which conta
minate the concentrate and need to be controlled during flotation.
In this paper, innovative techniques of single particle image analysis from both dry and wet samples have been tentatively used to assess the chromite particle size distribution and the chromite grade of samples taken from a secondary milling circuit. Preliminary results demonstrate excellent potential for online particle imaging making use of both the particle geometry (size, shape) and the optical properties (translucency).