초록 ▼

The invention relates to a method for extracting undissolved carbonized lignin from black liquor and products produced thereby. The invention further relates to the solid carbon thus extracted and the carbonized black liquor separated from said solid carbon. According to the invention black liquor f

The invention relates to a method for extracting undissolved carbonized lignin from black liquor and products produced thereby. The invention further relates to the solid carbon thus extracted and the carbonized black liquor separated from said solid carbon. According to the invention black liquor from an alkaline fractionation process is subjected to a hydrothermal carbonization process, an undissolved carbonized lignin is separated from the carbonized black liquor, the remaining carbonized black liquor is fed back into the alkaline fractionation process, and the undissolved carbonized lignin is separated from the carbonized black liquor is purified.

대표청구항 ▼

1. A method for extracting undissolved carbonized lignin from black liquor from an alkaline fractionation process, wherein black liquor having a dry matter content of at least 20 mass% is subjected in a first process step to a hydrothermal carbonization in a temperature range between 210° C. and 270

1. A method for extracting undissolved carbonized lignin from black liquor from an alkaline fractionation process, wherein black liquor having a dry matter content of at least 20 mass% is subjected in a first process step to a hydrothermal carbonization in a temperature range between 210° C. and 270° C., wherein the pH of the black liquor, before or during the hydrothermal carbonization, or the pH of the carbonized black liquor after the hydrothermal carbonization, is reduced to the extent that undissolved carbonized lignin is extracted with a yield of at least 20 mass%,and the pH of the black liquor, before and during the hydrothermal carbonization, and the pH of the carbonized black liquor after the hydrothermal carbonization, are at least 7,the undissolved carbonized lignin in a second process step is substantially separated off from the carbonized black liquor and the carbonized black liquor is fed back to the alkaline fractionation process,the inorganic components of the undissolved carbonized lignin separated off from the carbonized black liquor are reduced in a third process step by a wash andthe undissolved carbonized lignin is extracted with a dry matter content of greater than 40 mass%. 2. The method as claimed in claim 1, wherein an ash fraction of the undissolved carbonized lignin is lowered by the wash in the third process step to a maximum of 10 mass%. 3. The method as claimed in claim 2, wherein the undissolved carbonized lignin is washed in the third process step with water or an acid, in particular with sulfuric acid, and the ash fraction thereof is lowered in this manner. 4. The method as claimed in claim 1, wherein the pH of the black liquor before and during the hydrothermal carbonization and the pH of the carbonized black liquor after the hydrothermal carbonization are at least 8. 5. The method as claimed in claim 1, wherein the undissolved carbonized lignin is substantially separated off from the carbonized black liquor in the second process step at a pH of at least 7. 6. The method as claimed in claim 1, wherein the black liquor is fed in the first process step at a dry matter content of at least 25 mass%, in particular at least 30 mass%. 7. The method as claimed in claim 1, wherein the pH of the black liquor falls by at least one unit and at most to a pH of 8 during the hydrothermal carbonization. 8. The method for extracting undissolved carbonized lignin from black liquor as claimed in claim 1, wherein black liquor having a dry matter content of at least 20 mass% from a chemical pulp factory is subjected in the first process step to a hydrothermal carbonization at a temperature between 210° C. and 270° C. for at least 60 minutes and for a maximum of 600 minutes, wherein the pH of the black liquor falls by at least one unit and at most to a pH of 8during the hydrothermal carbonization andin this case undissolved carbonized lignin precipitates out of the black liquor at a yield of at least 20 mass%,the undissolved carbonized lignin in the second process step is substantially separated off from the carbonized black liquor,the carbonized black liquor is fed back to the chemical pulp factory,the inorganic components of the undissolved carbonized lignin separated off from the carbonized black liquor are reduced in the third process step by a wash and the undissolved carbonized lignin is extracted with a dry matter content of more than 40 percent by mass. 9. The method as claimed in claim 1, wherein the period and/or temperature of the hydrothermal carbonization is selected in such a manner that the pH of the carbonized black liquor is below the pH of the black liquor before the hydrothermal carbonization by at least one unit. 10. The method as claimed in claim 1, wherein the period of the hydrothermal carbonization is selected in such a manner that the pH of the carbonized black liquor is at least 8. 11. The method as claimed in claim 1, wherein the yield of at least 20 mass% of undissolved carbonized lignin is at least 50% achieved during the hydrothermal carbonization. 12. The method as claimed in claim 1, wherein the undissolved carbonized lignin is substantially separated off from the carbonized black liquor in the second process step and a filter cake is removed. 13. The method as claimed in claim 1, wherein the third process step is implemented within the second process step as filter cake wash. 14. The method as claimed in claim 1, wherein the third process step is implemented subsequently to the second process step. 15. The method as claimed in claim 1, wherein the pH before the hydrothermal carbonization is reduced to the extent that lignin precipitates out of the black liquor. 16. The method as claimed in claim 1, wherein the pH is lowered during the hydrothermal carbonization by increasing the fraction of biomass in the black liquor before and/or during the hydrothermal carbonization. 17. The method as claimed in claim 1, wherein the fraction of the chemical element carbon in the undissolved carbonized lignin based on the ash-free and dry mass is at least 60 percent by mass,the fraction of the chemical element carbon in the undissolved carbonized lignin based on the ash-free and dry mass is higher by at least 5 percent by mass than the fraction of the chemical element carbon in an ash-free and dry residue which is extracted in a complete evaporation of the black liquor used as starting material,the ash fraction of the undissolved carbonized lignin based on the dry mass is a maximum of 10 percent by mass,the ash fraction of the undissolved carbonized lignin based on the dry mass is lower by at least 50 percent by mass than the ash fraction of the dry residue which is extracted in a complete evaporation of the black liquor used as starting material,the softening temperature of the undissolved carbonized lignin is at least 200° C. andthe dry matter content of the undissolved carbonized lignin is at least 40 percent by mass. 18. The method as claimed in claim 1, wherein the fraction of the chemical element carbon in an ash-free and dry residue extracted from the carbonized black liquor is at least 60 percent by mass andthe fraction of the chemical element carbon in an ash-free and dry residue extracted from the carbonized black liquor is higher by at least 5 percent by mass than the fraction of the chemical element carbon in an ash-free and dry residue which is extracted in a complete evaporation of the black liquor used as starting material.