| CPC D21C 1/06 (2013.01) [D21C 3/022 (2013.01); D21C 3/026 (2013.01); D21C 9/02 (2013.01); D21C 9/163 (2013.01); D21C 11/0014 (2013.01); D21C 11/0035 (2013.01); D21C 11/02 (2013.01)] | 5 Claims |
|
1. A method for preparing fluff pulp from bamboos, comprising the following steps:
(1) alkali treatment of bamboos: treating a bamboo raw material with an alkali liquor in a cooking digester to obtain a treatment liquid and treated bamboos; wherein a temperature of the alkali treatment in the cooking digester is 60-90° C., a concentration of the alkali liquor is 60-100 g/L, and an alkali in the alkali liquor is sodium hydroxide; a ratio of mass of the bamboos to a volume of the alkali liquor is 1: (3-5) kg/L; and time of the alkali treatment is 60-120 minutes;
(2) separation of the treatment liquid: replacing the treatment liquid in the step (1) with a weak black liquor, and storing a replaced treatment liquid separately in a container for later use; wherein the weak black liquor refers to black liquor extracted from a pulp during washing; and the replacing refers to pumping the weak black liquor into the cooking digester to replace the treatment liquid in the step (1);
(3) cooking of the treated bamboos: replacing the weak black liquor with a warm black liquor, wherein the weak black liquor enters an original weak black liquor tank, then replacing the warm black liquor with a hot black liquor, wherein the warm black liquor enters a warm black liquor tank, after the replacement is completed, adding white liquor for cooking, after the cooking is completed, replacing the hot black liquor with the weak black liquor, wherein the hot black liquor enters a hot black liquor tank, and the warm black liquor enters the warm black liquor tank, and when a temperature of a pulp decreases, using a pump to pump the pulp to a pulp storage tower; wherein the warm black liquor refers to black liquor with a temperature greater than 100° C. but less than 140° C. obtained by replacing a cooked pulp with the weak black liquor; the hot black liquor refers to black liquor with a temperature of 140-165° C. obtained during the replacement and cooking; and the white liquor refers to cooking chemicals obtained from pulp production and alkali recovery, mainly comprising sodium hydroxide and sodium sulfide, wherein a ratio of an effective alkali dosage of the white liquor to mass of the bamboo raw material is 10.5%-14%, a sulfidity of the white liquor by NaOH is 25%-30%, a temperature of the cooking is 155-160° C., time of the cooking is 90-120 minutes, and the temperature decrease refers to the temperature dropping below 100° C.;
(4) washing of the pulp: washing the pulp in the pulp storage tower of the step (3) to obtain a washed pulp and a washed weak black liquor, sending the washed pulp to a washed pulp tower, and sending the washed weak black liquor to the weak black liquor tank;
(5) screening and cleaning of the pulp: screening the washed pulp to obtain a screened pulp and screened rejects, sending the screened pulp to a screened pulp tower for storage, re-screening the screened rejects to obtain an accepted pulp and tail rejects, reusing the accepted pulp, and collecting the tail rejects for later use, followed by cleaning to obtain a screened and cleaned pulp; wherein the screening refers to selecting and using a pressure screen with a width of 0.2-0.3 mm for a screen slot, wherein a mass percent concentration of the screened pulp is controlled between 0.5%-1%; and adopting two-stage screening, wherein first-stage screened rejects are sent to second-stage screening for secondary screening, the accepted pulp from the second-stage screening enters a pulp feed pump inlet of first-stage screening, and the tail rejects are collected for later use;
(6) screening of parenchyma cells: removing parenchyma cells and fine fibers from the screened and cleaned pulp using a microporous screen, sending a pulp with parenchyma cells and fine fibers removed to a long fiber pulp tower for storage, and sending a pulp containing parenchyma cells and fine fibers to a parenchyma cell pulp tower for storage and later use; wherein the microporous screen refers to a screen with a diameter between 0.1 and 0.5 mm, a mass percent concentration of the screened pulp is 0.1%-0.5%, the pulp with parenchyma cells and fine fibers removed is sent to the long fiber pulp tower for storage, and the pulp containing parenchyma cells and fine fibers is sent to the parenchyma cell pulp tower for storage and later use;
(7) oxygen delignification of the pulp with parenchyma cells and fine fibers removed: first concentrating the pulp with parenchyma cells and fine fibers removed, followed by the oxygen delignification to obtain a pulp after the oxygen delignification;
(8) ECF bleaching of the pulp after the oxygen delignification: performing ECF bleaching treatment of a D0EpD1P process on the pulp after the oxygen delignification to obtain bleached pulp, and sending the bleached pulp to a pulp board machine to obtain a bamboo fluff pulp board;
(9) ultrafiltration of the treatment liquid: treating the replaced treatment liquid obtained in the step (2) by ultrafiltration, obtaining a retentate and a permeate liquid, wherein the retentate is for separating hemicellulose, and continuing to use the permeate liquid for the alkali treatment in the step (1) after the permeate liquid is supplemented with sodium hydroxide; and
(10) recycling of the tail rejects: using the tail rejects obtained in the step (5) to prepare a tail reject pulp, concentrating and dehydrating the pulp containing parenchyma cells and fine fibers in the step (6) for recycling to obtain a parenchyma cell pulp, and mixing the tail reject pulp with the parenchyma cell pulp to prepare packaging paper.
|