Processing of sulfonated lignin-based liquor containing sulfite and ammonium ions, obtained in paper production, for re-use in building industry comprises optional replacement of some ammonium ions and treatment with formaldehyde

摘要

Process for treatment of a liquor based on sulfonated lignin containing both ammonium and sulfite ions discharged from paper production after treatment of wood with sulfur and ammonium compounds involves complexing the liquor with formaldehyde at 60-70[deg]C with agitation, optionally after replacement of part of the ammonium ions with calcium and/or sodium ions. The amount of formaldehyde added is the stoichiometric amount required for reaction with free NH4+> and SO32-> ions. Independent claims are given for: (a) the complexed product obtained in the above process; (b) use of the product as an additive for mortars and concretes, to enhance their workability; (c) use of the product for soil amendment; and (d) use of the product in building materials such as plaster or bricks.