A process of treating wood chips for reduction of the content of undesirable inorganic elements prior to cooking in a production line for chemical pulp, wherein the chips are (I) squeezed at atmospheric pressure by volumetric compression in a first compression means, whereby entrapped air escapes; (II) the squeezed chips are allowed to expand in a first acidic impregnation liquor, whereby the wood chips absorb first acidic impregnation liquor; (Ill) the expanded chips are: squeezed at atmospheric pressure by volumetric compression in a second compression means, whereby said first acidic impregnation liquor escapes; (IV) the squeezed chips from step (III) are allowed to expand in a second acidic impregnation liquor, whereby the chips absorb said second acidic impregnation Iiquor; and (V) the expanded chips are squeezed at atmospheric pressure by volumetric compression in a third compression means, whereby the second acidic impregnation liquor escapes from the volumes.
The present invention relates to a novel sulfite dissolving pulp suitable for high tenacity applications having: a) a viscosity of 700-1000 ml/g; b) a R18 value of 93-95.5%; c) a R10 value in of 92-94%; d) a PD of 9-15; e) a proportion of cellulose chains having a molecular weight below 25 KDa of less than 8% (w/w); and f) a proportion of cellulose chains having a molecular weight above 100 KDa of above 75% (w/w).
The present invention relates to a method for producing cellulose products comprising the following steps: a)providing a cellulose pulp, preferably by a method comprising pulping lignocellulosic biomass by a pulping process such that a cellulose pulp is obtained b) fractionating the cellulose pulp such that an over flow fraction and an under flow fraction is obtained c)swelling at least part of the cellulose fibers present in the over flow fraction by soaking at least part of the over flow fraction in a first liquid having a pH of 9.0 or lower such that a first set of swelled cellulose fibers is obtained d)producing at least one first cellulose product from the first set of swelled cellulose fibers obtained in step c) wherein the first cellulose product is a cellulose derivative and/or a cellulose dope.
The present invention relates to a method for production of a paper product comprising the following step: a) providing a chemical pulp b) adding lignosulfonate to the chemical pulp such that a chemical pulp comprising lignosulfonate is obtained c) beating the chemical pulp comprising lignosulfonate obtained in step b) such that a beated chemical pulp is obtained, and d) producing a paper product from the beated chemical pulp obtained in step c) The aim of the invention is to increase the efficiency of a beating of a chemical pulp.
There is provided a process for improving the quality of lignosulfonate at least partly derived form a spent sulfite cooking liquor in at least two steps, comprising: one step in which a lignosulfonate-containing fraction at least partly derived from the spent sulfite cooking liquor is subjected to filtration using a membrane having a cut-off of 40-150 kD (high cut-off) at the pressure, flow rate and temperature of the step and the permeate is recovered; and another step in which a lignosulfonate-containing fraction at least partly derived from the spent sulfite cooking liquor is subjected to filtration using a membrane having a cut-off of 1-20 kD (low cut-off) at the pressure, flow rate and temperature of the step and the retentate is recovered. Products, uses thereof as well as a system are also provided.
There is provided a process for improving the quality of lignosulfonate at least partly derived form a spent sulfite cooking liquor in at least two steps, comprising: one step in which a lignosulfonate-containing fraction at least partly derived from the spent sulfite cooking liquor is subjected to filtration using a membrane having a cut-off of 40-150 kD (high cut-off) at the pressure, flow rate and temperature of the step and the permeate is recovered; and another step in which a lignosulfonate-containing fraction at least partly derived from the spent sulfite cooking liquor is subjected to filtration using a membrane having a cut-off of 1-20 kD (low cut-off) at the pressure, flow rate and temperature of the step and the retentate is recovered. Products, uses thereof as well as a system are also provided.
