A surfactant treated bleached softwood kraft pulp fiber, useful as a starting material In the production of cellulose derivatives including cellulose ether, cellulose esters and viscose, is disclosed. Methods for making the kraft pulp fiber and products made from it are also described.

A method for controlling a gas flow separated from a suspension of medium consistency pulp. The pulp is treated in a pulp treatment apparatus including a first pump and a second pump, wherein the second pump is a degassing centrifugal pump provided with a degassing system which includes a degassing conduit in which a degassing valve is arranged for regulating a pressure difference between an inlet of the second pump and the degassing conduit. The degassing system also includes a pressurized degassing vessel working under overpressure and having an inlet and an outlet, wherein the outlet of the vessel is connected to a pressure control valve for maintaining a desired overpressure in the vessel.

A bleaching process of pulp is disclosed comprising performing a delignification of the pulp by carrying out in a following sequence: an enzymatic treatment step comprising contacting the pulp with a glycoside hydrolase family GH11 xylanase enzyme at a pH of at least 9.5 and a temperature of at least 85 C., an oxidation step wherein a bleaching agent is added, an alkaline extraction step wherein an alkaline agent is added, and recovering bleached pulp, wherein the GH11 xylanase enzyme has an ability to cause at least 20% reduction in viscosity of a xylan-containing mixture at 90 C. and pH 10.5, compared to the same mixture without any xylanase enzyme.

A bleaching process of pulp is disclosed comprising performing a delignification of the pulp by carrying out in a following sequence: an enzymatic treatment step comprising contacting the pulp with a glycoside hydrolase family GH11 xylanase enzyme at a pH of at least 9.5 and a temperature of at least 85 C., an oxidation step wherein a bleaching agent is added, an alkaline extraction step wherein an alkaline agent is added, and recovering bleached pulp, wherein the GH11 xylanase enzyme has an ability to cause at least 20% reduction in viscosity of a xylan-containing mixture at 90 C. and pH 10.5, compared to the same mixture without any xylanase enzyme.

The purpose of the present invention is to provide a method for producing recycled pulp fibers such that articles using the recycled pulp fibers can easily achieve a uniform whiteness and users are not prone to feel psychological resistance to articles using the recycled pulp fibers. This method is described below. The method is characterized by involving: a step for supplying, from a mixed solution supply port (32) to a treatment tank (31), a mixed solution (51) which contains superabsorbent polymers and pulp fibers derived from multiple types of used sanitary products; a step for supplying an ozone-containing gas (53) from an ozone-containing gas supply port (43) to a treatment solution (52) inside of the treatment tank (31); a step in which, by raising the ozone-containing gas (53) while lowering the superabsorbent polymers and pulp fibers in the treatment tank (31), the ozone-containing gas (53) is brought into contact with the superabsorbent polymers and the pulp fibers, and the pulp fibers are bleached to form recycled pulp fibers; and a step for discharging the treatment solution (52) from a treatment solution discharge port (33), wherein the recycled pulp fibers have a 0-10 YI with respect to a standard white plate.

A system for decolorization of material comprising cellulose including: a purification stage for removing non-cellulosic components from cellulose in alkaline process conditions; a first decolorization stage for decolorizing the material comprising cellulose in alkaline process conditions; and a second decolorization stage for decolorizing the cellulose in alkaline process conditions; wherein the first and second decolorization stages use ozone and hydrogen peroxide; wherein the purification stage and the second decolorization stage include washing the cellulose, wherein the purification stage, the first decolorization stage and the second decolorization stage are connected to the subsequent stage by a process line for feeding the cellulose; and wherein each washing arrangement is connected to the washing arrangement of a preceding stage by a filtrate line for feeding wash filtrate of the washer of a preceding stage.

A system for decolorization of material comprising cellulose including: a purification stage for removing non-cellulosic components from cellulose in alkaline process conditions; a first decolorization stage for decolorizing the material comprising cellulose in alkaline process conditions; and a second decolorization stage for decolorizing the cellulose in alkaline process conditions; wherein the first and second decolorization stages use ozone and hydrogen peroxide; wherein the purification stage and the second decolorization stage include washing the cellulose, wherein the purification stage, the first decolorization stage and the second decolorization stage are connected to the subsequent stage by a process line for feeding the cellulose; and wherein each washing arrangement is connected to the washing arrangement of a preceding stage by a filtrate line for feeding wash filtrate of the washer of a preceding stage.

A method of producing high yield chemical cellulosic pulp includes: (a) chemically pulping wood chips to separate lignin and liberate cellulosic fibers from the wood chips to generate a cellulosic pulp; (b) washing and screening the pulp of step (a); (c) pre-treating the washed pulp with oxygen; (d) optionally washing the treated pulp of step (c); (e) bleaching the pre-treated pulp in an extended duration oxidative bleaching stage; (f) optionally washing the bleached pulp of step (e); and (g) optionally further oxidatively or reductively bleaching the bleached pulp in a shorter duration bleaching stage, wherein the bleached pulp is produced at a yield of greater than 60% based on the weight of the pulped wood chips (dry basis).

A method for recycling textile material comprising cellulose, the method comprising treating (2) the textile material using Hot Caustic Extraction, HCE, and, after said treating, bleaching (4) material obtained from said treating The HCE is carried out at a temperature of at least 100 C. The bleaching comprises at least one of ozone bleaching at a total ozone charge of more than 5 kg/odt; chlorine dioxide bleaching, and hydrogen peroxide bleaching at a total charge of more than 13 kg/odt.

A method for recycling textile material comprising cellulose, the method comprising treating (2) the textile material using Hot Caustic Extraction, HCE, and, after said treating, bleaching (4) material obtained from said treating The HCE is carried out at a temperature of at least 100 C. The bleaching comprises at least one of ozone bleaching at a total ozone charge of more than 5 kg/odt; chlorine dioxide bleaching, and hydrogen peroxide bleaching at a total charge of more than 13 kg/odt.