Gravity Separation
Posted on January 6, 2021 Separation
Gravity separation exploits density differences to separate materials. It is used in mining to remove solids from liquids (thickening or clarification), separate immiscible liquids (oil/water, flotation), or enhance separation using centrifugal forces.
In principle, gravity separation is simple, requiring only a vessel and sufficient residence time. However, it often requires careful design of inlets / outlets, internal flow management, vessel size optimization, or even chemical treatment for best performance:
• Inlet design: High velocity feed streams from relatively small pipes must be well-distributed across the entire vessel. Mixing energy and adverse flow patterns inside the vessel that inhibit separation must be reduced.
• Outlet design: Removing the separated materials from the vessel must be accomplished while maintaining the separation performance. Underflow and overflow design parameters include stream density, flow split, and launder design.
• Supplementary streams: Some processes require the removal of fines or other slowly separating components for additional treatment.
• Variations in Feed Properties: Flow rates (turn-up / turn-down), material properties, and feed compositions may vary widely in some processes and the vessel must be designed accordingly.