🔧 Can Rotary Pumps Be Used to Pump Slurries? Special Cautions
Rotary pumps are widely used in industries for in‑plant processes and pipeline transfer where metered flow and medium‑to‑high discharge pressures are required. But when it comes to slurry handling, special considerations must be taken into account. Slurries contain solid particles suspended in liquid, which can cause abrasive wear, binding, and efficiency loss if pumps are not properly selected and operated.
🔹 Rotary Pumps and Slurry Handling
- Rotary pumps can handle slurries when precise flow control and steady discharge pressure are needed.
- Efficiency depends on the clearances between pumping elements.
- Slurries with hard particles increase wear and reduce pump life.
- Proper design and operating conditions are essential to avoid damage.
🔹 Factors Affecting Rotary Pump - Performance in Slurries
1. Solid Concentration
- The concentration of solids has the greatest effect on slurry fluidity.
- Example: Paper stock slurry (5–15% by weight) shows different shear characteristics depending on concentration.
2. Particle Size and Shape
- Pump clearances must be greater than the maximum particle size to prevent binding and wedging.
- Larger clearances reduce wear but may increase slip (internal leakage), lowering efficiency.
3. Hardness of Solids
- Soft solids (e.g., polymer chains) cause minimal wear.
- Fibrous solids may carry hard particles, increasing abrasion.
- Very hard irregular particles (e.g., sand, carbon) cause severe erosion at rotor tips and housing surfaces.
4. Pump Speed
- High speeds increase shear and relative velocity of solids, accelerating wear.
- For abrasive slurries, pump speeds should be significantly reduced compared to non‑abrasive fluids.
🔹 Special Cautions for Rotary Pumps in Slurry Service
- ✅ Select proper clearances to accommodate particle size.
- ✅ Reduce pump speed to minimize wear and shear.
- ✅ Evaluate slurry concentration and adjust pump design accordingly.
- ✅ Inspect regularly for wear on rotors, housing, and seals.
- ✅ Use abrasion‑resistant materials for pump components when handling hard solids.
- ✅ Balance efficiency vs durability – larger clearances reduce wear but may increase slip.
🔹 Applications of Rotary Pumps in Slurries
- Paper industry – handling paper stock slurry.
- Mining – transferring coal slurry and mineral suspensions.
- Wastewater treatment – sludge and fibrous slurry pumping.
- Chemical processing – viscous slurries with controlled flow requirements.
🔹 Key Takeaways
- Rotary pumps can be used for slurry pumping, but require careful design and operation.
- Solid concentration, particle size, hardness, and pump speed are critical factors.
- Always ensure clearances exceed particle size to prevent binding.
- Reduce pump speed for abrasive slurries to extend equipment life.
- Regular inspection and use of wear‑resistant materials are essential for reliable operation.
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