CHAPTER 6 EXPERIMENTAL
The results show that the addition of DPOOI reduces the viscosity of the suspensions. Figure 6.55 illustrates that the addition of DPOO 1 to a ferrosilicon-magnetite suspension at a specific gravity of 2.2 reduces the viscosity of the suspensions by a considerable amount. The addition of Ig DPOOllkg reduces the viscosity by up to 20%. Addition of a further 1 gram and 3 g DPOOllkg does not appear to further reduce the viscosity of the suspensions by much. A similar trend is observed for some of the other specific gravities. At a specific gravity of 2.3 the reduction in the viscosity of the suspensions at DPOO 1 additions equal to 2g DPOO llkg is not as pronounced as at Ig DPOOllkg. However, additions of 5g DPOOllkg results in a further reduction of the viscosity.
At a specific gravity of 2.4 the viscosity reduction for both Ig and 2g DPOOI additions is relatively high. But at 5g DPOOllkg additions, the viscosity reduction observed was much lower than that observed at the 1 and 2 g DPOOllkg additions. At specific gravity 2.5 there appears to be little difference between the viscosity reductions at 1 and 2 g DPOO llkg additions. A much larger drop in suspensions viscosity was observed at 5 g DPOOllkg additions. From a specific gravity 2.6 to 2.8, the drop in viscosity increases between Ig and 2g DPOOllkg additions. There appears to be little benift in increasing the dosage ofDPOOI additions to 5g DPOOllkg.
The results above show that DPOO 1 is capable of reducing the viscosity of suspensions of ferrosilicon-magnetite mixtures. At low specific gravities (2.2 to 2.4), some of the graphs with DPOOI additions are close to the plain ferrosilicon graph at the same specific gravity. The results show that DPOO 1 has an effect of bringing the viscosities of the ferrosilicon-magnetite suspensions towards those of plain ferro silicon suspensions. However, it is not quite clear from the results which dosage ofDPOOI is more effective. It appears at though the optimum dosage lies somewhere between 19 and 2g DPOOllkg additions.
CHAPTER 6
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EXPERIMENTAL
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Shear rate (sol)
Figure 6.62 Effect of DPOOI on ferrosilicon-magnetite #1 mixtures (2:1) at sp.gr.2.2
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Figure 6.63 Effect ofDPOOl on ferro silicon-magnetite #1 mixtures (2:1) at sp.gr.2.3
CHAPTER 6
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Figure 6.64 Effect ofDPOOl on ferro silicon-magnetite #1 mixtures (2:1) at sp.gr.2.4
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Figure 6.65 Effect ofDPOOl on ferrosilicon-magnetite #1 mixtures (2:1) at sp.gr.2.5
CHAPTER 6
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Figure 6.66 Effect of DP001 on ferrosilicon·magnetite #1 mixtures (2:1) at sp.gr.2.6
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Figure 6.67 Effect ofDP001 on ferrosilicon·magnetite #1 mixtures (2:1) at sp.gr.2.7
CHAPTER 6
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Figure 6.68 Effect of DPOOI on ferro silicon-magnetite #1 mixtures (2:1) at sp.gr.2.8
Table 6.8 summarises the results shown in the above figures. Again the percentage viscosity reduction was taken as an average over the entire range of shear rates.
Table 6.8 Viscosity reduction on FerrosiliconiMagnetite #1 (2:1) mixtures
% Viscosity Reduction
Specific Gravity 19DPOO1/k~ 2XDPOOllk~ 5XDPOO1/k~
2.2 10.0 7.3 14.0
2.3 13.4 8.0 -6.1
2.4 4.7 5.8 -22.8
2.5 -5.4 -6.4 -14.8
2.6 8.2 15.8 -3.2
2.7 16.2 22.5 9.7
2.8 14.8 22.7 9.0
The figures above also show that the viscosity of the suspensions is reduced at some of DPOO 1 additions. At a specific gravity of 2.2 the addition of Igram DP001 / kilogram reduces the viscosity of the suspensions by up to 10%. There is not much difference observed through the addition of a further 1 gram. Additions of 5grams DPOOI / kilogram reduce the viscosity by
CHAPTER 6 EXPERIMENTAL
14.0%. At a specific gravity of 2.3, the viscosity begins to increase after additions of 19ram DP001 / kilogram. At Sgrams DP001 / kilogram additions the viscosity of the suspensions exceeds that of the pure suspensions. a similar sort of trend is observed at specific gravities 2.4 to 2.6. At a specific graVity of 2.S there appears to be no reduction in viscosity. In fact, there is an increase in the viscosity of the suspensions at all DP001 additions. At specific gravities 2.7 and 2.8 the viscosity is reduced by additions up to 2grams DP001 / kilogram. At Sgrams DP001 / kilogram additions, the viscosity appears to also increase.
For the ferro silicon-magnetite suspensions at a ratio of 2:1, the presence of magnetite is much lower than ferrosilicon. The stability of the suspensions is thus not as stable as ferrosilicon- magnetite mixtures at a ratio of 1: 1. The measurements of these suspensions were much more difficult at the lower specific gravities. The presence of DPOO 1 could have also added to the higher settling rates of the media particles. The accumulation of solid particles at the base of the cup could haye resulted in the simulation of viscosities in excess of plain suspensions at the lower specific gravities.
The graphs above also show that the viscosities of suspensions at some DPOO 1 additions are close to those of ferrosilicon suspensions at the same specific gravities, particularly at low shear rates.
At specific gravities 2.7 and 2.8, DP001 reduces the difference in viscosity between ferrosilicon- magnetite suspensions and pure ferrosilicon suspensions by as much SO% at high shear rates.