Coal Preparation » Fine Coal
The ACARP funding allowed the design of a production sized Jameson Cell test rig with internal sampling arrangements and for investigations into combustibles recovery under different Jameson Cell operating conditions.
Reduction in downcomer turbulence through operation with a lower jet velocity results in a substantial increase in the combustibles recovery within the Jameson Cell downcomer and for the overall Jameson cell combustibles recovery of coarse coal. This is achieved with up to 42% decrease in power consumption.
Downcomer Combustibles Recovery
Decreasing the jet velocity from 15m/s to 11m/s resulted in a 12% increase in Jameson Cell downcomer recovery of +1mm particles and a 10% increase in the plus 0.71 minus 1mm fraction. No loss in fine coal recovery was encountered using these operating parameters.
Increasing the jet velocity from 15m/s to 18m/s resulted in a substantial decrease in downcomer coarse coal recovery.
Overall Jameson Cell Combustibles Recovery
Decreasing the jet velocity from 15m/s to 11m/s resulted in a 22% increase in overall Jameson Cell combustibles recovery of +1mm particles and a 11.5% increase in the plus 0.71 minus 1mm. No loss in fine coal recovery or product quality was encountered using these operating parameters.
Increasing the jet velocity from 15m/s to 18m/s resulted in a substantial decrease in overall Jameson Cell coarse coal recovery.
The recovery of coal particles in most flotation machines including the Jameson Cell decreases as the particle size becomes coarser than 0.5 mm. One perceived reason for this traditional drop in recovery in the Jameson Cell is the level of turbulence in the downcomer. Recent basic research conducted by Greg Harbort at the University of Queensland, through a collaborative ARC funded research project between the University and Xstrata Technology, indicates that the relationship between turbulence, air entrainment and bubble surface area in the downcomer could be optimised further. The work, which was conducted in a 100mm downcomer using an air water system, showed that the optimum condition for this relationship could be achieved with lower turbulent energy.
Table 1 Size by Size Downcomer Combustibles Recovery
| -0.038 | -0.063 | -0.125 | -0.25 | -0.5 | -0.71 | -1.0 | +1 |
+0.038 | +0.063 | +0.125 | +0.25 | +0.5 | +0.71 |
11.3m/s at 1.77 Air- to-Pulp ratio | 82 | 93 | 93 | 94 | 91 | 85 | 94 | 88 |
Table 2 Size by Size Overall Jameson Cell Combustibles Recovery
| -0.038 | -0.063 | -0.125 | -0.25 | -0.5 | -0.71 | -1.0 | +1 |
+0.038 | +0.063 | +0.125 | +0.25 | +0.5 | +0.71 |
11.3m/s at 01.77 Air-to-Pulp ratio | 92 | 99 | 97 | 97 | 98 | 99 | 97 | 93 |