EFFICIENT METHODS AND COMPOSITIONS FOR RECOVERY OF PRODUCTS FROM ORGANIC ACID PRETREATMENT OF PLANT MATERIALS

1 . A method of producing a lignin composition, the method comprising the steps of:

a) separating lignin from a lignin suspension produced from organic acids pretreatment of plant material by centrifugation, and

b) cleaning the lignin in the centrifuge by multiple applications of wash solution onto the lignin during centrifugation, to form multiple centrifugates, and

c) recovering a first centrifugate and a second centrifugate for use in hemicellulosic juice concentration, and

d) recycling a third centrifugate for separating the lignin in the concentrated extraction liquor in the separating step of the process, and

e) discharging the lignin from the centrifuge.

2 . The method according to claim 1 , wherein the centrifuge is a scraper centrifuge.

3 . The method according to claim 1 , wherein the centrifuge is equipped with a spraying device for delivering wash solution.

4 . The method according to claim 1 , wherein the centrifuge rotates continuously through the entire process.

5 . The method according to claim 1 , wherein the wash solution comprises formic acid, acetic acid, and water.

6 . The method according to claim 1 , wherein the wash solution consists solely of water.

7 . The method according to claim 1 , wherein the multiple applications of wash solution comprise a first application of a wash solution comprised of high organic acids content washing water, a second application of a wash solution comprised of low organic acids content washing water, and a final application of a wash solution comprised of fresh water.

8 . The method according to claim 1 , wherein the wash solution has a content of formic acid of 0% to 30% by weight.

9 . The method according to claim 1 , wherein the wash solution has a content of acetic acid of 0% to 20% by weight.

10 . The method according to claim 1 , wherein the first centrifugate is comprised of the liquids separated from the lignin suspension applied to the centrifuge.

11 . The method according to claim 1 , wherein the second centrifugate is comprised of the first wash solution applied to the lignin in the centrifuge.

12 . The method according to claim 1 , wherein the first and second centrifugates are collected and used for hemicellulosic juice production.

13 . The method according to claim 1 , wherein the third centrifugate is comprised of the second and any subsequent wash solutions applied to the lignin in the centrifuge.

14 . The method according to claim 1 , wherein the third centrifugate is recycled to the lignin precipitation step.

15 . The method according to claim 1 , wherein first centrifugate comprises 10% to 60% of the total centrifugates.

16 . The method according to claim 1 , wherein the second centrifugate comprises 10% to 30% of the total centrifugates.

17 . The method according to claim 1 , wherein the third centrifugate comprises 10% to 50% of the total centrifugate.

18 . The method according to claim 1 , wherein the lignin is 90% to 99% pure, based on the total weight of the cleaned lignin.

19 . A lignin composition obtained by a method according to claim 1 .

20 . The lignin composition according to claim 19 , wherein the lignin is 90% to 99% pure, based on the total weight of the cleaned lignin.