Alkali salts can be recovered from clarified liquor following lignin biomass separation through regenerating alkali pulping liquor by recausticizing. Soluble organic compounds remaining in clarified liquor can be anaerobically digested for methane production before recausticizing with burnt lime.
Liquor treatment applies to soda pulping or kraft pulping liquors. For soda pulping of straw and similar high silica residues, silica absorbed into liquor separates with lignin during the biomass precipitation. As there is no necessity for thermal processing of liquor, a requirement of silica elimination is avoided. The separation procedure requires inexpensive polymeric and surface active agents, with use of commercial sulfuric acid for pH reduction. The process is carried out at ambient temperatures. Capital equipment requirements are minimal.
The technology was invented by Dr. Hassan El-Shall of the University of Florida. U.S. patent no. 5,635,024 issued June 4, 1997, titled "Process for Separating Lignins and Dissolved Organic Compounds from Kraft Spent Liquor" describes the innovative and unique features of the process. A second U. S. patent, no. 6,632,327 issued October 14, 2003, is titled "Treating Spent, Waste, Alkaline Digestion Liquor from Paper Pulping Operations and Product". Related patents have been issued or are pending in several national venues.
BOUNTIFUL APPLIED RESEARCH is licensor of the El-Shall spent digestion liquor separation process. Harrison R. Cooper is president of Bountiful Applied Research.
Contact BARC by e-mail - hcooper "at" BARC-usa.com. Telephone 801 295-2345 and FAX 801 295-2346.
LINKS: Click on yellow cube.
Patent text on record at U. S. Patent and Trademark Office web site
Poster presentation at San Francisco TAPPI Pulping Conference October 1997 (30 Kb file - requires Acrobat reader)
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SLIDE PRESENTATION - MINI PILOT PLANT AT UNIVERSITY OF FLORIDA ENGINEERING RESEARCH CENTER (MAY 2000).   This link is 4 meg.   Illustrates continuous lignin separation from black liquor, and also results of decolorizing (removal of lignin) from wash water at various contamination levels.
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Most recent revision December 2004