Nanocellulose production co-located at a pulp and paper mill

A process for producing a nanocellulose material, said process comprising:

• (a) providing a bleached pulp material, wherein said bleached pulp material is a chemical pulp, a chemimechanical pulp, a chemithermomechanical pulp, or a combination thereof, wherein said bleached pulp material is obtained from a distinct process, and wherein said bleached pulp material received in this step (a) has already gone through complete chemical pulping with bleaching, chemimechanical pulping with bleaching, and/or chemithermomechanical pulping with bleaching;
• (b) in a digestor, fractionating said bleached pulp material in the presence of an acid and water, and optionally a solvent, to generate cellulose-rich solids and a liquid containing hemicellulose and lignin, wherein said bleached pulp material is fed to said digestor at a solids concentration of from 30 wt % solids to 50 wt % solids;
• (c) mechanically treating said cellulose-rich solids to form cellulose fibrils and/or cellulose crystals, thereby generating a nanocellulose material having a crystallinity of at least 60%;
• and
• (d) recovering said nanocellulose material,
• wherein said process is co-located with a pulping process that generates said bleached pulp material.