Process for producing lignin products

Claim 1

A PROCESS FOR OBTAINING LIGNIN FROM LIGNOCELLULOSE MATERIAL WHICH COMPRISES TREATING SAID MATERIAL WITH AN AQUEOUS SOLUTION OF AN ALKALI METAL CARBONATE AT A TEMPERATURE OF FROM ABOUT NORMAL ROOM TEMPERATURE TO ABOUT THE BOILING POINT OF SAID SOLUTION AT ATMOSPHERIC PRESSURE AND IN CONCENTRATION SUFFICIENT TO PROVIDE NOT SUBSTANTIALLY MORE THAN ABOUT 15 PARTS OF SAID ALKALI PER 100 PARTS OF DRY LIGNOCELLULOSE MATERIAL FOR DISSOLVING FROM THE MATERIAL LIGNIN AND POLYSACCHARIDES-OTHER-THAN-CELLULOSE AND LEAVING A LIGNOCELLULOSIC RESIDUE, SEPARATING THE RESULTING AQUEOUS ALKALINE TREATING SOLUTION FROM THE SAID LIGNOCELLULOSIC RESIDUE, SUBSTANTIALLY NEUTRALIZING SAID ALKALINE SOLUTION AND CONDITIONING THE SAID AQUEOUS SOLUTION BY ESTABLISHING A SALT CONCENTRATION THEREIN IN AN AMOUNT SUFFICIENT TO CAUSE PRECIPITATION OF A SUBSTANTIAL AMOUNT OF ITS LIGNIN CONTENT, SEPARATING THE THUS PRECIPITATED LIGNIN FROM THE RESIDUAL SOLUTION, AND TREATING THE SAID LIGNIN WITH AN AQUEOUS SOLVENT FOR EXTRACTING COMPONENTS DISSOLVED BY SAID SOLVENT.