Processing

Please wait...

Settings

Settings

Goto Application

1. WO2021006798 - METHOD FOR DISSOLVING PULP FROM RECYCLED TEXTILE MATERIAL

Note: Text based on automatic Optical Character Recognition processes. Please use the PDF version for legal matters

[ EN ]

CLAIMS:

1. A method for the manufacturing of cellulose dissolving pulp, said method comprising:

providing a source of mechanically or chemically pre-treated cellulosic pulp comprising at least 3 % by weight recycled textile material to at least one of a

brownstock washing step, an oxidative alkaline pulp bleaching step, and an acidic cellulose pulp treatment step of a kraft or sulfite pulp mill fiberline, and

recovering said cellulose dissolving pulp from the kraft or sulfite pulp mill fiberline,

the method further comprising one or both of;

a) recycling spent chemicals, effluents and/or organic residues from cellulosic pulp pre-treatment steps, pulp washing steps, pulp bleaching or pulp acidic treatment steps to a kraft or sulfite mill recovery boiler, or

b) recycling spent chemicals, effluents and/or organic residues from cellulosic pulp pre-treatment steps, pulp washing steps, pulp bleaching or pulp acidic treatment steps, after optional neutralization, to a kraft or sulfite pulp mill secondary effluent treatment plant.

2. The method of claim 1 , wherein the textile material comprises at least one of recycled cotton, cotton linters, recycled viscose fibers, and waste or leftovers from cotton or viscose textile plants.

3. The method of any preceding claims, wherein:

said pulp mill is a kraft dissolving pulp mill having brownstock washers, an alkaline oxygen bleaching step, and a bleaching sequence;

said bleaching sequence comprises one or both of a chlorine dioxide (D) stage and an ozone (Z) bleaching stage; and

recycled textile pulp is charged to the pulp mill fiber line upstream the pulp mill screen room after digesters or recycled textile pulp is charged to any bleaching or pulp treatment step upstream of pulp drying.

4. The method of claim 1 , wherein said pulp mill is a sulfite pulp mill and said providing a source of mechanically or chemically pre-treated cellulosic pulp comprises the introduction of said cellulosic pulp into a brownstock washing step or upstream a peroxide (P) bleaching, an ozone (Z) bleaching or a peracetic acid (Paa) bleaching step.

5. The method of any of the preceding claims, wherein alkalinity provided in an alkaline bleaching step is provided by charging oxidized white liquor.

6. The method of any of the preceding claims further comprising:

treating cellulosic pulp originating from both virgin wood and/or recycled textile material by oxidative bleaching and/or acidic treatments to produce a dissolving quality pulp with brightness exceeding 85 ISO, and

washing and drying said cellulosic pulp to form a dried cellulose dissolving pulp.

7. The method of any preceding claims wherein:

the cellulosic pulp comprising recycled textile material is co-processed with cellulosic textile fiber material in at least one of an oxygen bleaching step (O), a chlorine dioxide bleaching step ( D), a peroxide bleaching step (P) , an ozone step (Z) and an acid step (A) and wherein the proportion of cellulosic textile fiber material is at least corresponding to 5 % of the total pulp flow and that co-processed and intermixed combined dissolving pulp is dried in a pulp drying plant prior to baling.

8. The method according to claim 7, further comprising pretreating the cellulosic pulp comprising recycled textile material by one or more of a hydrothermal,

thermomechanical, alkaline swelling treatment, treatment with supercritical C02 and a mechanical fabric disintegration procedure prior to charging the pulp to the kraft or sulfite pulp mill fiber line.

9. The method according to claim 8, wherein hydrothermal pre-treatment of the textile pulp material is performed in aqueous media at a temperature in the range of 100 C to 220 C in closed pressure vessel systems.

10. The method according to claim 9 wherein the aqueous media further comprises one or more of ozone, hydrogen peroxide, perborates, alkali hydroxide and surfactants.

11. The method according to any of claims 7 to 10, wherein aqueous effluents from any hydrothermal treatment or thermomechanical treatment is concentrated and finally incinerated in a recovery boiler or utilized for manufacturing of biogas.

12. The method according to any of claims 7 to 11 , wherein a thermomechanical treatment comprises a steam explosion treatment wherein textile pulp material is treated by steam and optional additives at a temperature in the range of 100-250 C in a closed pressurized vessel for a time period of from 1 minute to 220 minutes where after pressure is abruptly released forming a cellulosic pulp with cellulose polymers in the Dp range of 150 -700 repeating anhydroglucose units and at least on residue stream that is further treated in the kraft or sulfite pulp mill chemicals recycling plants.

13. The method according to any of claims 7 to 12, wherein a textile material pulp pre-treatment step is adjusted by charge of chemicals and/or selection of temperature and retention time conditions so that the Dp range of the resulting pulp is in the range from about 200 to 1000 prior to charging the pulp to the kraft or sulfite pulp mill fiberline.

14. The method according to any of claims 7 to 13, further comprising processing at least a portion of spent bleaching chemicals by concentration in an evaporator and incineration in a recovery boiler furnace thereby generating molten sodium carbonate.

15. The method according to claim 14 wherein sodium carbonate is causticized to form white liquor and wherein at least a portion of the white liquor is oxidized prior to charging at least a portion of oxidized white liquor to an oxygen (O) or peroxide (P) step bleaching cellulosic pulp comprising recycled textile material.

16. The method according to any of the preceding claims wherein recycled cotton, cotton linters, recycled viscose fibers and waste or leftovers from cotton or viscose textile plants is directly or indirectly charged to a sulfite pulp mill bleach plant pulp washing step, ozone bleaching step (Z) and a peroxide bleaching step (P) and wherein an effluent from a bleaching step is concentrated by evaporation or membrane filtration.