Control of continuous crystallization
Motivation
Chemical recovery in the pulp mill is based on leaching and recrystallization. Disturbances in the leaching stage induce variations in crystal size distribution. This creates problems in the centrifuges resulting in capacity problems or even breaks in the operation.
Implementation
A Pixact Crystallization Monitoring (PCM) system is used to measure crystal size and the fraction of fines in the suspension.
Benefits
The PCM system provides the means to react quickly to any changes in crystal population. In addition, observations based on the PCM data led to several improvements in the process operation.
Process parameters
| Crystalline product | Na2SO4, Na2CO3 |
| Size distribution | 20…1000µm |
| Solids concentration | 45 w-% |
| Temperature | 90°C |
| Pressure | 4 Bar |
| Other remarks | pH 10-11 |
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