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Table 4 :
Mass balance on catalytic species in the lab reactor
% of loaded catal in -100µm % of loaded catal in +100µm % of loaded catal in reactor
Exp
Cu Sn Zn
Cu Sn
Zn
Cu Sn Zn
1
50% 48% 21%
4% 6% 2%
54% 54% 24%
4
46% 47% 28%
5% 19% 4%
51% 66% 32%
7
48% 56% 39%
5% 16% 7%
53% 72% 47%
8
42% 56% 26%
3% 9% 2%
45% 66% 28%
Based on these results, it seems that zinc addition to the reactor make species less
volatile / more accumulated in the reactor, and that aluminium make zinc and copper
more mobile. Tin seems not being affected by aluminium addition.
Discussion
In any tested conditions, a low quantity of copper (3% to 7%) was transported from
activated particles to fresh silicon in the lab reactor conditions. The amount of
transported copper was not highly affected by the conditions evaluated.
On the contrary, tin and zinc content in the fraction above 100µm (silicon added on
day 2) varied a lot with the experimental conditions. Tin transport under nitrogen
seemed significantly favoured by temperature.
Zinc addition seemed to increase catalyst retention in the lab reactor, whereas
aluminium seemed to make catalytic species more mobile
Calculation of surface concentration of catalyst on fraction +100µm after transfer
indicated quite stable concentration in copper, systematically lower (2 to 4 times) than
copper concentration in the initial composition. Tin surface concentration are in most
of the cases significantly higher than in the initial composition whereas zinc surface
concentration is systematically lower.
135