Pulping process without a recovery furnace

Abstract

A novel process has been discovered whereby acid is added to the lignocellulosic material (black liquor containing lignin). The acid renders the lignin insoluble thus enabling it to be separated from the lignocellulosic material. This allows the chemical value of various components to be reclaimed. This process enables important environmental and economic benefits to be achieved. The invention obviates the need for a recovery boiler which burns the sugars and the lignin. Additionally, sodium salts are precipitated out of the process. Sodium carbonate from outside sources is used in the novel process. The supply of energy to the separation process is from a source other than the recovery furnace.

I claim:  
     
         1 . A pulping process without a lignin-fired recovery furnace, said process includes recovering lignin and sugars from a lignin containing solution, comprising the steps of: 
 supplying energy to a digester and blow tank for the generation of a lignin containing solution and pulp, said energy being totally supplied from a source other than a lignin-fired recovery furnace;    separating said lignin containing solution and said pulp;    precipitating polymer-grade lignin from the lignin containing solution by adding an acid selected from the group consisting of sulfuric acid, acetic acid and phosphoric acid or by adding a gas selected from the group consisting of carbon dioxide and sulphur dioxide;    removing said precipitated lignin from said lignin containing solution leaving inorganic ions to react with said selected acid forming inorganic salts and leaving organic sugars in solution; and,    separating said inorganic salts and said organic sugars from said solution.    
     
     
         2 . A process as claimed in  claim 1  wherein said acid is acetic acid which produces sodium acetate.  
     
     
         3 . A process as claimed in  claim 1  wherein said acid is phosphoric acid which produces a sodium phosphate.  
     
     
         4 . A separation process for separating lignin from a lignocellulosic material without using lignin as a fuel, comprising the steps of: 
 supplying energy to said separation process, said energy being totally supplied from a source other than said lignin:    separating lignin from said lignocellulosic material creating a lignin containing solution;    precipitating lignin from said lignin containing solution by adding an acid selected from the group consisting of sulfuric acid, acetic acid, and phosphoric acid or by adding a gas selected from the group consisting of carbon dioxide and sulfur dioxide; and,    removing said precipitated lignin from said lignin containing material leaving inorganic salts and leaving organic sugars from said solution.    
     
     
         5 . A separation process for separating lignin from a lignocellulosic material without using lignin as a fuel, comprising the steps of: 
 supplying energy to the separation process, said energy being totally supplied from a source other than said lignin:    separating lignin from said lignocellulosic material creating a lignin containing solution;    precipitating lignin from said lignin containing solution by adding an acid selected from the group consisting of sulfuric acid, acetic acid, and phosphoric acid or by adding a gas selected from the group consisting of carbon dioxide and sulfur dioxide; and,    adding a compound having a sodium ion as part thereof.