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SAP processing

Bühler solutions for SAP meet the most demanding market requirements for hygiene products. After the polymerization the polymer is in a jellylike form available. It needs further thermal and mechanical processing to reach the final consistency needed for manufacturing consumer hygiene products.

Thermal treatment includes drying and subsequent cooling steps, which are performed using belt dryers. Further mechanical processing includes grinding and sizing using standard Bühler machines. For transporting the intermediate product between all steps of thermal and mechanical processing, gentle pneumatic conveyances are used.

Grinding and sifting of Superabsorbent

Efficient grinding is a process which has a great impact on product quality. Grinding can be done with different principles like hammering, cutting, shearing or impacting.

For a size reduction of particles in the range from 2 - 12 mm down to 0.15 – 0.75 mm roller mills are the most efficient process principle, especially when few fines shall be generated. Roll grinders linked with efficient sifters are an advanced solution. After each grinding step the product is fractioned into fines, product and coarse particles. Only the oversized particles are fed to the next reduction step. This serial link of grinding and sifting is the way to reach top results, i.e. fines are minimized. For SAP sizing Bühler recommends a 3-step reduction process.

If the superabsorbent gel is dried by a belt dryer then a pre-grinding step typically with a nibbler is necessary. So it is sure that the feed is uniform and contains no oversized coarse particles.

In grinder operation the feeder evenly distributes the feed along the roller gap. The material flows between the rolls, which rotate countercurrent at different speed. By rotation the feed is grinded by compression and shearing. Material discharge happens by gravity preferred with some suction of a pneumatic transport line.

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