Alumina Evaporator Overview
An alumina evaporator is specialized equipment used in the Bayer process for concentrating sodium aluminate liquor to precipitate alumina hydrate (Al(OH)₃). It plays a critical role in alumina refining, ensuring energy-efficient separation of aluminum oxide from bauxite ore.
Key Components & Working Principle
Feed System
Preheated aluminate liquor (~30% solids) is fed into the evaporator.
Evaporation Chamber
Utilizes falling film or forced circulation designs to enhance heat transfer.
Heat Source
Typically steam (0.3–0.8 MPa) or waste heat from calcination.
Condensate Recovery
Condensed water is recycled to reduce freshwater consumption.
Types of Alumina Evaporators
| Type | Advantages | Applications |
|---|---|---|
| Falling Film | High thermal efficiency, low scaling | Final concentration stage |
| Forced Circulation | Handles high-viscosity slurries | Pre-concentration of liquor |
| Multiple-Effect | Energy savings (3–6 effects) | Large-scale refineries (>1Mt/y) |