US 12,442,134 B2
Method for preparing unbleached biomechanical pulp from straws and full utilization of by-products
Zhongjian Tian, Jinan (CN); Ruiming Wang, Jinan (CN); Xingxiang Ji, Jinan (CN); Yinkai Ge, Jinan (CN); Jiachuan Chen, Jinan (CN); Guihua Yang, Jinan (CN); and Hao Ma, Jinan (CN)
Assigned to Qilu University of Technology, Jinan (CN)
Filed by Qilu University of Technology, Jinan (CN)
Filed on Dec. 23, 2021, as Appl. No. 17/561,482.
Claims priority of application No. 202011639137.3 (CN), filed on Dec. 31, 2020.
Prior Publication US 2022/0205179 A1, Jun. 30, 2022
This patent is subject to a terminal disclaimer.
Int. Cl. D21C 5/00 (2006.01); C05F 5/00 (2006.01); D21C 1/02 (2006.01); D21C 1/04 (2006.01); D21C 1/06 (2006.01); D21C 9/02 (2006.01); D21C 11/00 (2006.01); D21H 11/12 (2006.01); D21H 17/00 (2006.01)
CPC D21C 5/005 (2013.01) [C05F 5/008 (2013.01); D21C 1/02 (2013.01); D21C 1/04 (2013.01); D21C 1/06 (2013.01); D21C 9/02 (2013.01); D21C 11/0007 (2013.01); D21H 11/12 (2013.01); D21H 17/005 (2013.01)] 9 Claims
 
1. A method for preparing an unbleached biomechanical pulp from straws and full utilization of by-products, wherein comprising the following steps:
(1) cutting a physically selected dedusted air-dried straw into a ready-for-use raw material with a length of 3-6 cm; and collecting a straw that cannot be used as the ready-for-use raw material;
(2) placing the ready-for-use raw material into a reactor, treating with an alkaline compound enzyme according to a solid/liquid ratio of 1:4-1:8 W/V, during the treatment, adding KOH to adjust the pH value of the straw to 7-14, and controlling the treatment time within 30-90 min to obtain a treated straw; and collecting the wastewater generated during the enzyme-alkali co-treatment;
(3) taking out the treated straw in step (2), and further treating with hot alkali (KOH) water and steam at a temperature of 80-120° C. to obtain a hot alkali treated straw;
(4) refining the hot alkali treated straw in step (3) in one or more stages to make the beating degree at 25-55° SR to obtain a refined pulp;
(5) washing with water the refined pulp to obtain a biomechanical pulp; defibrating the biomechanical pulp by a defibrater and mixing evenly to obtain the unbleached biomechanical pulp; and collecting the washing water;
evaporating and concentrating the wastewater generated in the enzyme-alkali co-treatment and the washing water to obtain a residue, and recovering the heat energy for the hot alkali (KOH) water and steam treatment of step (3); mixing the residue with the straw that cannot be used as the ready-for-use raw material in step (1), and adjusting the pH to make a fertilizer.