The crystallization module receives the saturated feed after evaporation and concentration; through cooling or further evaporation, the solute precipitates as crystals, and after thickening, centrifugal separation, and drying, a solid salt product is obtained. It is a key unit for solid-liquid separation at the end of ZLD.
Process Principle
- The saturated feed is further concentrated or cooled in the crystallizer; after entering the supersaturated zone, crystals nucleate and grow.
- After the crystal slurry is thickened in a thickener to increase solids content, it enters a centrifuge or filter for solid-liquid separation.
- Part of the mother liquor is returned to the system or discharged; impurity accumulation must be controlled to maintain crystal quality.
Product Features
- Can convert dissolved salts into solids, enabling near-zero liquid discharge of wastewater and salt recovery.
- Crystallization type is selectable and can be determined according to the material solubility curve and product particle size requirements.
- Can seamlessly connect with evaporation units such as MVR and MED to form a continuous production line.
- Product salt purity and particle size are affected by mother liquor impurities and operating conditions, and must be commissioned according to actual operating conditions.
Application Industries
- End-of-pipe crystallization and mixed-salt solidification for ZLD projects.
- Segregated crystallization and recovery of industrial salts such as sodium chloride and sodium sulfate.
- Salt crystallization and purification in lithium battery and new energy material production.
- Crystallization and mother liquor treatment in the chemical and hydrometallurgical industries.
Specifications and Models
| Parameter | Unit | Typical value |
|---|---|---|
| Treatment capacity (crystal slurry) | m³/h | 1–50 (typical) |
| Crystallization type | — | Forced circulation / DTB / OSLO |
| Discharge solids content | % | 10–30 (typical) |
| Product moisture content (after centrifugation) | % | 3–8 (typical, depending on the material) |
| Operating temperature | ℃ | Determined from the material solubility curve (typical value depends on the system) |
| Material | — | Stainless steel 316L / duplex steel / titanium |
The data in the table are common ranges for similar equipment and are for selection reference only; specific specifications, models, materials, connections, and control methods must be confirmed during the selection stage based on water quality, treatment scale, and site conditions.