Mechanical Slurrying
Recycled paperboard and dry pulp sheets must be reduced to a homogeneous suspension of individual fibers before papermaking can begin. The process of hydrapulping uses high mechanical shear and water action to break the hydrogen bonds holding the dry sheet together. This step is carried out in a large vat equipped with a powerful rotor.
Fiber Separation
Liquid water and dry fibers are fed into the pulp chest where the rotor creates a violent vortex. During hydrapulping, the intense turbulence forces the fibers to rub against each other, which accelerates wetting and fiber swelling without shortening the wood fibers. Chemical additives such as sodium hydroxide can be introduced to assist in ink release and wax emulsification during the recycling process.
The rotor design and extraction plate holes screen out large contaminants such as plastics or wire staples, allowing only the clean slurry to pass to the next stage of preparation.
Consistency Range
Batch operations are performed at different pulp concentrations depending on the raw material and contaminant level. High-density hydrapulping runs at greater solids content to reduce water use and heat consumption. This method minimizes the breakdown of plastic contaminants, making them easier to screen out.
