Recovery of fibers from a fiber processing waste sludge

Abstract

A process of recovering a useful population of fibers and fines from the waste stream of fiber processing facility is disclosed. Steam explosion of the fiber-containing waste stream is used to increase the separation efficiency of the fibers from the ash. The steam explosion also enhances the quality of the recovered fibers and fines, providing a population of recovered fibers which can be incorporated into the fiber component of a tissue or absorbent paper product.

Description

[0001] This invention relates to a process for recovering a useable population of fibers and fines from the waste sludge of a fiber production or fiber handling facility.[0002] In particular, this invention provides a steam explosion process and a resulting product which permits the separation of a useful population of fibers and fines from the waste streams of fiber production processes such as a waste paper recovery operation or from the waste stream of a papermaking process. The process is useful in fiber and fine recovery from white water waste streams from paper making operations and waste sludge from the de-inking and processing of waste paper. The present invention not only increases the amount of usable fibers and fines recoverable from the waste stream, but increases the fiber quality of the recovered fibers. Additional benefits include a concomitant reduction in the solid volume of the waste stream and increases the usable fiber content available from the initial raw mater...

AI Technical Summary

Benefits of technology

[0034] The invention sets forth a process by which a supply of treated, recovered fibers and fines have superior fiber quality characteristics for absorbent products than similar untreated fibers and fines. The present invention enables both the volume and dry solid content of waste streams to be reduced by the recovery of additional fibers and fines from the waste stream. As a result, it is possible to increase the percentage of fibers and fines from the starting material. It is further possible to incorporate the increased percentage of fibers and fines into a finished paper product without lowering the quality of the finished product.

Problems solved by technology

In particular, efforts to recover the fibers and fines from the waste sludge streams of paper fiber recovery plants have been limited, in part, by the high ash content of the sludge.

The high ash content renders the recovered fibers and fines undesirable for quality end products.

As can be expected, disposal of the unused white water and de-inked effluents results in costs to the papermaking facility.

Landfill and land spreading sites are being depleted at an alarming rate, and the establishment of new sites is difficult due to environmental concerns.

In addition, the cost associated with using landfills to dispose of sludge is constantly increasing.

However, these techniques generally require the use of complex methods and expensive equipment.

In addition, attempts to recycle sludge to make paper have been unsuccessful because the process is inefficient due to drainage problems resulting from the presence of slow drying fines which tend to clog the wires and other equipment.

While considerable prior art exists with regard to methods for handling, utilizing or recycling of sludge as outlined above, in actual fact there has been little commercial implementation.

It is likely that environmental and regulatory pressures to recycle paper and paper products will increase.

Furthermore, wood pulp, even though it is a renewable resource, is becoming more expensive.

Further, none of the references teach or suggest that the useful fiber characteristics of an individual fiber can be improved for absorbent products by the steam explosion process.

The fibers and fines have historically proven difficult to isolate and contain a high degree of contaminants such as ash.

In particular, fines have been considered a waste product in the tissue and paper production industry since fines typically retard water drainage, confer low air permeability to the formed webs or sheets, exhibit a higher degree of chemical reactivity which results in greater chemical cost, and tend to promote greater fiber-fiber bonding which, while increasing product strength, imparts an often undesired stiffness to the paper product.

In particular, the fiber component from paper recycling waste sludge has heretofore been considered unsalvageable in that the reclaimed fibers have had an unacceptably high ash content.

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