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.