A system (1) for refining lignocellulosic biomass material (A) comprising a presteaming bin (2), a dewatering device (3), a preheater (4), a defibrator (9) comprising at least one refining zone (14) wherein steam is generated during refining of said biomass material so that a pressure peak occurs, a blowpipe (19), and a first steam flow path (D) arranged to convey steam from said refining zone to said presteaming bin (2). The system further comprises a second steam flow path (E) arranged to convey steam from said refining zone to said presteaming bin, wherein said first and second steam flow paths are connected to the refining zone on opposite sides of the pressure peakin a biomass material transport direction, and wherein said first and second steam flow paths are separate from said blow pipe. The invention also relates to a process for refining lignocellulosic biomass material.

There is provided a method of producing a highly refined pulp, comprising the steps of: providing a pulp; subjecting the pulp to a first conical refining step in at least one conical refiner comprising refining plates having a bar width of 0.5-1.5 mm, such as about 1.0 mm, and a groove width of 1.0-2.0 mm, such as 1.4-2.0 mm, such as about 1.6 mm; and subjecting the pulp from the first conical refining step to a second conical refining step in at least one conical refiner comprising refining plates having a bar width of 0.5-1.5 mm, such as about 1.0 mm, and a groove width of 0.8-1.6 mm, such as 1.0-1.5 mm, to obtain the highly refined pulp.

Methods of preparing partially dried or essentially completely dried compositions comprising microfibrillated cellulose and an inorganic particulate material may include microfibrillating a fibrous substrate comprising cellulose in an aqueous environment by grinding in the presence of an inorganic particulate material to form an aqueous composition comprising microfibrillated cellulose and inorganic particulate material, wherein the fibrous substrate comprising cellulose has a Canadian Standard freeness equal to or less than 450 cm, wherein the fibrous substrate to the inorganic particulate material are in a ratio of about 99.5:0.5 to about 0.5:99.5, and wherein the microfibrillated cellulose has a fibre steepness of from about 20 to about 50; by treating the aqueous composition comprising microfibrillated cellulose and inorganic particulate material to remove at least a portion or substantially all of the water of the aqueous composition to form a partially dried or essentially completely dried composition comprising microfibrillated cellulose and inorganic particulate material.

Methods of preparing partially dried or essentially completely dried compositions comprising microfibrillated cellulose and an inorganic particulate material may include microfibrillating a fibrous substrate comprising cellulose in an aqueous environment by grinding in the presence of an inorganic particulate material to form an aqueous composition comprising microfibrillated cellulose and inorganic particulate material, wherein the fibrous substrate comprising cellulose has a Canadian Standard freeness equal to or less than 450 cm, wherein the fibrous substrate to the inorganic particulate material are in a ratio of about 99.5:0.5 to about 0.5:99.5, and wherein the microfibrillated cellulose has a fibre steepness of from about 20 to about 50; by treating the aqueous composition comprising microfibrillated cellulose and inorganic particulate material to remove at least a portion or substantially all of the water of the aqueous composition to form a partially dried or essentially completely dried composition comprising microfibrillated cellulose and inorganic particulate material.

Methods of preparing partially dried or essentially completely dried compositions comprising microfibrillated cellulose and an inorganic particulate material may include microfibrillating a fibrous substrate comprising cellulose in an aqueous environment by grinding in the presence of an inorganic particulate material to form an aqueous composition comprising microfibrillated cellulose and inorganic particulate material, wherein the fibrous substrate comprising cellulose has a Canadian Standard freeness equal to or less than 450 cm, wherein the fibrous substrate to the inorganic particulate material are in a ratio of about 99.5:0.5 to about 0.5:99.5, and wherein the microfibrillated cellulose has a fibre steepness of from about 20 to about 50; by treating the aqueous composition comprising microfibrillated cellulose and inorganic particulate material to remove at least a portion or substantially all of the water of the aqueous composition to form a partially dried or essentially completely dried composition comprising microfibrillated cellulose and inorganic particulate material.

Methods of preparing partially dried or essentially completely dried compositions comprising microfibrillated cellulose and an inorganic particulate material may include microfibrillating a fibrous substrate comprising cellulose in an aqueous environment by grinding in the presence of an inorganic particulate material to form an aqueous composition comprising microfibrillated cellulose and inorganic particulate material, wherein the fibrous substrate comprising cellulose has a Canadian Standard freeness equal to or less than 450 cm, wherein the fibrous substrate to the inorganic particulate material are in a ratio of about 99.5:0.5 to about 0.5:99.5, and wherein the microfibrillated cellulose has a fibre steepness of from about 20 to about 50; by treating the aqueous composition comprising microfibrillated cellulose and inorganic particulate material to remove at least a portion or substantially all of the water of the aqueous composition to form a partially dried or essentially completely dried composition comprising microfibrillated cellulose and inorganic particulate material.

A system for treating recycled cellulosic fibers to improve paper, board and tissue quality; the system involves fractionating recycled fibers into a short fiber portion and a long fiber portion. The short fiber portion is split into an original short fiber portion and a refinable portion. The refinable portion is processed into glue pulp. The glue pulp is refined to targeted, measured fiber properties. Varying amounts of the glue pulp, original short unrefined fibers, and long unrefined fibers are blended together to form an optimized slurry that is processed by a paper machine into an optimized recycled paper product. The process provides for improved drainage with the same or better paper properties allowing for cost reductions in fabrication.

A system for treating recycled cellulosic fibers to improve paper, board and tissue quality; the system involves fractionating recycled fibers into a short fiber portion and a long fiber portion. The short fiber portion is split into an original short fiber portion and a refinable portion. The refinable portion is processed into glue pulp. The glue pulp is refined to targeted, measured fiber properties. Varying amounts of the glue pulp, original short unrefined fibers, and long unrefined fibers are blended together to form an optimized slurry that is processed by a paper machine into an optimized recycled paper product. The process provides for improved drainage with the same or better paper properties allowing for cost reductions in fabrication.

The refining of a fibrous pulp is monitored and controlled by capturing at least one image of a pulp sample, determining the amount of all fibers or non-fibrillated fibers in the at least one image, determining the amount of fibrillated fibers in the at least one image, determining the relation between fibrillated fibers and all fibers or non-fibrillated fibers in the pulp on the basis of the amount of fibrillated fibers and the amount of all fibers or non-fibrillated fibers in the at least one image, generating a control parameter on the basis of the determined relation between fibrillated fibers and all fibers or non-fibrillated fibers in the pulp, and controlling fiber refining by at least one pulp refining device on the basis of the control parameter.

The refining of a fibrous pulp is monitored and controlled by capturing at least one image of a pulp sample, determining the amount of all fibers or non-fibrillated fibers in the at least one image, determining the amount of fibrillated fibers in the at least one image, determining the relation between fibrillated fibers and all fibers or non-fibrillated fibers in the pulp on the basis of the amount of fibrillated fibers and the amount of all fibers or non-fibrillated fibers in the at least one image, generating a control parameter on the basis of the determined relation between fibrillated fibers and all fibers or non-fibrillated fibers in the pulp, and controlling fiber refining by at least one pulp refining device on the basis of the control parameter.