US 12,391,807 B2 · Extraction of valuable components from bark

Abstract

The present invention relates to a process for the extraction of valuable components from a tannin-rich bark raw-material, by carrying out an alkaline cooking step, followed by acid precipitation to separate the valuable components from the remaining bark pulp. The invention also relates to the use of said process on a bark side stream of a chemical pulping plant, whereby the liquor remaining after the extraction of the present process is returned to a stream of the wood pulping process, typically to a black liquor stream, while the spent pulp can be processed further, e.g. by bleaching to give dissolved pulp.

Claims19

Dependent claims

A process for extraction of valuable components from a tannin-rich bark raw-material, the process comprising:

carrying out a pre-treatment on the bark raw material, before an alkaline cooking step, to remove, or at least to decrease the content of silicon and ashes, the pre-treatment comprising washing the bark material with one or more acids or chelating agents at a temperature of 30-50° C., and separating and collecting solids for the alkaline cooking step, and carrying out the alkaline cooking step of the tannin-rich bark raw-material, followed by acid precipitation to provide a solid fraction comprising the valuable components, wherein the alkaline cooking step comprises using a white liquor comprising sodium hydroxide (NaOH) and sodium sulfide (Na2S), thereby obtaining a black liquor comprising polyphenols.

Dependencies are inferred from the claim text.

Extraction of valuable components from bark

Life of this patent

Extraction of valuable components from bark

Life of this patent

Abstract

Claims19