Kg h m2 gl m2 settl glgl

1.Sulfuric acid 0.06 1.1 18.2

2.Aluminum sulfate 0.15 1.4 9.3

3.Glucose trisulfate 0.15 1.4 9.3 4.Sulfite liquor 0.83 1.4 1.7

5.Lignin sulfonic acid 0.83 1.4 1.7

The results show that precipitant number 6 is far the best due to the fast settling. The example shows furthermore, the importance of the use of polyflocculants. The more rapid settling implies that the need for settling area is reduced significantly.

30 60 90 120 150

Figure C4.1. Settling is plotted versus time for precipitation with six different précipitants. The number used are explained in Table C4.1.

Figure C4.2. Settling rate in cm / min. is plotted versus the slurry concentration at the transition layer for the six précipitants. The numbers refer to the précipitants explained in Table C4.1.

Figure C4.3. Weight of solid produced kg / h m2 ,Ws , for different values of C = concentrations of solid in the transition layer. Numbers see Table C4. 1.

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