What is pulp refining?

Pulp refining is the controlled mechanical treatment of pulp fibres to modify flexibility, swelling, fibrillation, bonding surface, fines and fibre dimensions for the required paper grade.

What are the main types of pulp refiners?

Common industrial types include single-disc, double-disc, twin-flow and conical refiners. Hollander beaters are also used in batch and speciality applications.

Is mechanical pulping the same as pulp refining?

No. Mechanical pulping produces pulp from raw material, while refining normally treats pulp after it has been produced. Mechanical-pulping processes may also use refiners.

Does more refining always increase paper strength?

No. Tensile and burst may initially improve, but excessive treatment can cut fibres, reduce tear strength, slow drainage, lower bulk and increase energy consumption.

Why does pulp refining reduce drainage?

Refining increases fibre swelling, flexibility, surface fibrillation and often fines content, creating a denser fibre network that retains water more strongly.

What is net specific refining energy?

Net specific refining energy is the useful refiner energy above no-load losses divided by dry fibre throughput.

What is specific edge load?

Specific edge load relates net refining power to the total plate-bar cutting-edge length passing per second and is used as an indicator of treatment intensity.

When should a paper mill conduct a refiner audit?

A refiner audit is useful when strength is unstable, drainage is poor, motor load fluctuates, plate life is short, energy per tonne is high or expected production cannot be achieved.