US 12,454,792 B2
Method for preparing biomechanical unbleached pulp from wheat straw and full utilization of by-products thereof
Xingxiang Ji, Jinan (CN); Ruiming Wang, Jinan (CN); Zhongjian Tian, Jinan (CN); Jiachuan Chen, Jinan (CN); Guihua Yang, Jinan (CN); and Gaojin Lv, 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. 17/561,237.
Claims priority of application No. 202011641351.2 (CN), filed on Dec. 31, 2020.
Prior Publication US 2022/0205177 A1, Jun. 30, 2022
This patent is subject to a terminal disclaimer.
Int. Cl. D21C 1/02 (2006.01); C05F 7/02 (2006.01); C12P 1/00 (2006.01); D21B 1/06 (2006.01); D21C 1/06 (2006.01); D21C 5/00 (2006.01); D21C 9/02 (2006.01); D21C 11/00 (2006.01); D21C 11/10 (2006.01); D21D 1/20 (2006.01); D21H 11/12 (2006.01)
CPC D21C 5/005 (2013.01) [C05F 7/02 (2013.01); C12P 1/00 (2013.01); D21B 1/061 (2013.01); D21C 1/02 (2013.01); D21C 1/06 (2013.01); D21C 9/02 (2013.01); D21C 11/0007 (2013.01); D21C 11/10 (2013.01); D21D 1/20 (2013.01); D21H 11/12 (2013.01); C12P 2201/00 (2013.01)] 10 Claims
 
1. A method for preparing biomechanical unbleached pulp from wheat straw and full utilization of by-products thereof, wherein the method comprises the following steps:
(1) cutting a physically-screened and dust-removed wheat straw into small pieces of 1-8 cm as raw materials, putting them into a processor or a reactor, and performing a hot water treatment according to a liquid ratio of 1:4-1:8 for 15-90 min to obtain a mixture of hot water and a hot water treated wheat straw in the reactor or processor; meanwhile collecting rotten wheat straw which cannot be used for processing;
(2) adding KOH to the mixture of hot water and the hot water treated wheat straw in the reactor or processor, adjusting pH of the hot water to 10-14, and performing a hydrothermal saturation and softening treatment on the wheat straw to obtain a hydrothermally saturated and softened wheat straw; collecting waste lye;
(3) treating the hydrothermally saturated and softened wheat straw with an alkaline biological compound enzyme in a biological processor for 30-90 min in a liquid ratio of 1:3-1:8 (W/V) to obtain an enzyme treated wheat straw; collecting wastewater produced in an enzyme treatment stage;
(4) refining the enzyme treated wheat straw after treatment in step (3) with a pulp refiner to obtain a refined wheat straw; and
(5) washing the refined wheat straw to obtain a biomechanical pulp; disintegrating and mixing the biomechanical pulp homogeneously with a fiber disintegrator to obtain an unbleached pulp, collecting refining washing water;
treating the waste lye, the wastewater produced in the enzyme treatment stage, and the refining washing water with a multi-effect evaporator to prepare residue by evaporation and concentration, and recycling heat energy for use in the hot water treatment stage of step (1); mixing the residue and the rotten wheat straw which cannot be used for processing in step (1) and adjusting pH thereof to prepare fertilizer.