In excess of one million tonnes of recovered paper is collected annually in South Africa. This is 62% of the available recoverable paper. Paper fibres deteriorate in strength during each recycling cycle.

Fractionation is the process of classifying pulp according to specific fibre properties, including fibre length, cell wall thickness (CWT) and degree of fibrillation.

Using fractionation, a pulp of better quality and uniformity may be produced. This project involved the testing of two types of fractionating equipment viz., hydrocyclones and screens to fractionate two types of recycled fibre pulp viz; common mixed recovered paper (C+) and heavy letter one (HL 1).

After fractionation, the refined long fibre fraction (LFF) or rejects was combined with the unrefined short fibre fraction (SFF) or accepts, to achieve a better quality pulp, than the unfractionated, unrefined feedstock.

The hydrocyclone was found to be the best method for fractionating both the C+ and HL 1 grades of recovered paper with respect to tensile strength.

Download technical paper here.