In this study, the effect of speed was investigated on the breakage rate of UG2
platinum ore in a batch mill of 5 dm3 and 175 mm internal diameter. One size fraction
method was carried out to perform the experiment. Five mono-sized fractions in the
range of 1.180 mm to 0.212 mm separated by β2 series interval were prepared. The
fractions were milled at different grinding times (0.5, 2, 4, 15 and 30 min) and three
fractions of mill critical speed were considered (20%, 30%, and 40%). The target of
critical speed below 50% was due to the need of lower energy consumption in milling
processes. The selection and breakage function parameters were determined and
compared for fractions of critical speed.
First the grinding kinetics of the ore was determined and it was found that the
material breaks in non-first order manner. Thereafter, effective mean rate of
breakage was determined. It was found that the rate of breakage increased with
increase of mill speed and optimum speed was not reached in the range of chosen
mill speed fractions. Again the rate of breakage was plotted as a function of particle
size, the optimum size was 0.8 mm when milling at 30% critical speed. As for 20% and
30% optimum size was not reached. The selection function parameters estimated at
30% critical speed were π0 = 0.04 minβ1
, πΌ = 1.36, π = 0.9 mm, and Ξ = 3. Breakage
function parameters were determined and was noticed that the material UG2
platinum ore is non-normalised, i.e. Ξ¦ value was changing from 0.25 to 0.90
depending on feed size and mill speed. The parameters π½ and πΎ were constant at 7.3
and 1.17 respectively. / College of Science, Engineering and Technology / M. Tech. (Chemical Engineering)
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:unisa/oai:uir.unisa.ac.za:10500/26498 |
| Date | 11 1900 |
| Creators | Makgoale, Dineo Mokganyetji |
| Contributors | Mulenga, Francois |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Dissertation |
| Format | 1 online resource (xxi, 115 leaves) ; color illustrations, graphs (chiefly color), application/pdf |
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