METHOD AND APPARATUS FOR RECOVERING FIBRE AND FIBRE-BASED SOLIDS FROM A FILTRATE OF THE MECHANICAL OR CHEMI-MECHANICAL WOOD PULP INDUSTRY, SAID FILTRATE CONTAINING BOTH SOLIDS AND LIPOPHILIC EXTRACTIVE MATERIAL

摘要

The present invention relates to a separation method of fibre and fibre-based material and lipophilic extractive material; the method permits a reduction in the water consumption of a pulp mill and the use of wood species having higher extractives content in the mechanical and chemi-mechanical pulp production. In a preferred embodiment of the invention, a decanter centrifuge is used to recover solids and to separate solids and lipophilic extractives. With a decanter centrifuge a situation is reached in which the colloids containing lipophilic extractive material do not settle but fibre and fibre-based solids settle due to a higher density.