Flashmix high shear mixers help in fumed silica dispersion

Wahal LPM high shear mixers can significantly reduce process times in fumed silica slurry preparation due to their ability to address the unique challenges associated with fumed silica. Here’s how:

Challenges in Fumed Silica Slurry Preparation:

Fumed silica presents several difficulties when preparing slurries:

 

• • Low Bulk Density & Dusting: Fumed silica is extremely lightweight and fine, making it prone to floating on the liquid surface and creating significant dust, which is a safety and handling concern.
  • Difficulty in Wetting Out: Due to its high surface energy and low density, fumed silica resists wetting by liquids, often forming “fish eyes” or agglomerates that are hard to break down.
  • Agglomeration: Fumed silica particles have a strong tendency to form agglomerates (clumps) due to interparticle forces (van der Waals forces, electrostatic charging). These agglomerates need to be effectively dispersed to achieve a homogeneous slurry with desired properties.
  • High Viscosity Build-up: As fumed silica is dispersed, it acts as a rheology modifier, causing the viscosity of the slurry to increase rapidly. This can make further mixing difficult with conventional equipment.
  • Long Processing Times: Traditional low-shear mixers often require extended mixing times to achieve even a suboptimal dispersion, leading to inefficiency.

How Wahal LPM High Shear Mixers Overcome These Challenges and Reduce Process Times:

Wahal LPM (Powder/Liquid Mixers) high shear mixers are specifically designed to handle challenging powder-liquid dispersions like fumed silica. They achieve significant time reduction through:

 

 

1. Rapid Powder Induction and Wetting:
   • Powerful Suction: Wahal LPM mixers utilize advanced rotor-stator technology that creates a powerful vacuum or high-speed flow, drawing powders (like fumed silica) directly into the high-shear zone below the liquid surface. This eliminates floating powders and greatly accelerates the “wetting out” process, preventing the formation of large agglomerates from the start.
   • Sub-Surface Addition: By adding powder directly into the high-shear zone, dusting is minimized, and the powder is wetted instantaneously, preventing the formation of “fish eyes” that would otherwise require long times to break down.
2. Intense Shear for De-agglomeration:
   • Rotor-Stator Mechanism: The core of a high shear mixer is the precisely engineered rotor and stator. The high-speed rotation of the rotor within the close-tolerance stator generates intense mechanical and hydraulic shear forces.
   • Rapid Particle Size Reduction: These forces effectively break down the agglomerates of fumed silica into individual particles or much smaller nano-aggregates. This de-agglomeration is crucial for achieving the desired rheological properties and stability of the slurry.
   • Short Cycle Times: The intense and continuous shear ensures that all material passes through the workhead multiple times in a short period, leading to rapid and thorough dispersion, significantly reducing batch cycle times (often by 80% or more, as reported by users of similar high-shear technologies).
3. Homogeneous Slurry Formation:
   • Uniform Dispersion: The high shear ensures that the fumed silica is uniformly distributed throughout the liquid phase, creating a truly homogeneous slurry free from lumps or inconsistencies. This consistent dispersion is vital for product quality and performance.
   • Effective Viscosity Management: Even as the viscosity increases, the powerful mixing action maintains vigorous in-tank movement, preventing dead zones and ensuring continued dispersion.
4. Customization and Optimization:
   • Wahal Engineers specialize in customized solutions. Their homogenizers can be tailored to specific industry needs, optimizing the mixing process for fumed silica by fine-tuning rotor-stator designs and machine parameters for optimal performance.

In summary, Wahal LPM high shear mixers reduce process times in fumed silica slurry preparation by:

• Minimizing initial wetting issues and dusting.
• Rapidly breaking down fumed silica agglomerates with intense shear.
• Achieving uniform and stable dispersions quickly.
• Enabling higher solid concentrations to be processed efficiently.

This leads to significant improvements in batch cycle time, production efficiency, and overall product quality for fumed silica slurries.

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