Lignin preparation and method for its manufacture
AssigneeLigno Tech Sweden AB
InventorsWilhelm Aarsrud, Hans Bergstrom, Ingemar Falkehag
Life of this patent
Estimating the term…
Abstract
The invention relates to a lignin preparation prepared from black liquor derived from an alkali delignification process, such as the sulphate process, soda process or polysulphide process. The lignin preparation comprises mainly lignin and at least the major part of the sodium content of the lignin separated from the black liquor deriving from such processes has been replaced with calcium, therewith to provide a lignin preparation having improved properties which render the preparation more suitable for use as fuel.
Claims17
A lignin fuel preparation which upon combustion will form an ash having an elevated melting point, said preparation containing predominantly lignin obtained by precipitation from black liquor derived directly from an alkali delignification process selected from the group consisting of the sulphate process, the soda process and the polysulphide process, and wherein the original sodium content of the lignin has been reduced by treating the lignin precipitate so as to be less than 2% by weight calculated on the dry weight of the lignin, and that sodium removed from the lignin has been replaced by calcium such that the calcium content of the lignin exceeds 2% by weight calculated on the dry weight of the lignin, said preparation further including an acid component selected from the group consisting of kaolin, silicon dioxide, aluminum oxide and slag, ash of an acid nature, and mixtures thereof.
A method for producing a lignin fuel preparation, which upon combustion will form an ash having an elevated melting point, said preparation containing lignin derived from an alkali delignification process selected from the group consisting of the sulphate process, the soda process and the polysulphide process, which comprises extracting said lignin by precipitation from black liquor directly derived from one of said processes, separating the lignin precipitate from a black liquor residue by filtration, and removing at least a major part of the sodium content of the lignin by washing with an acid capable of forming a soluble calcium salt, down to a pH value of 9 or less.
Dependencies are inferred from the claim text.