Abstract: An arrangement for separating chemicals comprises a first distillation column (100) and the first distillation column (100) receives a mixture that comprises water and at least two organic acids and extractant that comprises at least one of the following: hexanol, an ester of hexanol with said at least one organic acid and 2-methylpentanol. The first distillation column (100) forms a heterogeneous azeotrope of water and extractant at its top (104) on the basis of reactive heteroazeotropic extractive distillation not controlling chemical reactions between the extractant and said at least two organic acids, said first distillation column (100) removing the azeotrope through its top (104) for separating water from the organic acid.

Abstract: The invention relates to manufacturing hydrolyzable cellulose and further, if desired, sugars from lignocellulosic material by means of formic and performic acid treatment.

Abstract: The invention relates to a process for producing pulp from a fibre-based raw material using, as the cooking reagent, a solvent mixture which is based on organic acids and also contains furfural. The method is applicable to herbaceous plants, in particular.

Abstract: The invention relates to a process for recovering and producing chemicals in a pulp production process where organic chemicals, such as formic acid and acetic acid, are used as cooking chemicals. The process of the invention is based on regeneration of cooking acids and formation of additional cooking acids and furfural by evaporating the cooking liquor and then separating acetic acid, formic acid, furfural and water. The separation is preferably carried out by distillation using the furfural formed in the process as a distilling aid in the distillation.

Abstract: The invention relates to a process for treating bleaching liquors from pulping processes based on organic acids. The process is characterized in that inorganic acid, such as nitric acid, phosphoric acid and/or sulphuric acid, is added into a bleaching liquor obtained from the bleaching or a stage closely associated with bleaching, whereby organic acids contained in the bleaching liquor are released into the bleaching liquor. The organic acids are then separated from the bleaching liquor and recycled to the cooking stage to be used as cooking chemicals. The nitrogen-, phosphor- and/or sulphur-containing product thereby produced, from which organic acids have been separated, is recovered to be used as a fertilizer or as raw material for a fertilizer.

Abstract: A process based on formic acid cooking for producing pulp from herbaceous plants and deciduous trees by using acetic acid as an additional cooking chemical. The obtained pulp can be used in fine paper and board production as short-fibered material, for instance. The invention also relates to a process for adjusting the hemicellulose content of the pulp in connection with the formic acid cooking by using acetic acid as an additional cooking chemical.

Abstract: The invention relates to a process for producing cellulose and a fertilizer by-product by using a closed cycle of cooking chemicals and process waters. In the process of the invention, the pulp is bleached by at least partly using potassium hydroxide as a bleaching chemical. Thus, a bleach concentrate rich in potassium is obtained from the bleach filtrate, which bleach concentrate is combined with ashes obtained from the burning of lignin and other organic matter recovered from pulp production as a by-product, in order to be used as a potash fertilizer. The bleach-concentrate can also be used as a potash fertilizer as such. The invention also relates to a potash fertilizer obtained this way.

Abstract: The invention relates to a process for producing cellulose and a fertilizer by-product by using a closed cycle of cooking chemicals and process waters. In the process of the invention, the pulp is bleached by at least partly using potassium hydroxide as a bleaching chemical. Thus, a bleach concentrate rich in potassium is obtained from the bleach filtrate, which bleach concentrate is combined with ashes obtained from the burning of lignin and other organic matter recovered from pulp production as a by-product, in order to be used as a potash fertilizer. The bleach concentrate can also be used as a potash fertilizer as such. The invention also relates to a potash fertilizer obtained this way.

Abstract: The invention relates to a method for removing chemically bound formic acid from a material containing the same, in the presence of free formic acid. The method is characterized in that chemically bound formic acid is allowed to react to free formic acid at a normal pressure, at a temperature of less than 100° C., the initial contact free formic acid being about 3 to 20%. The reaction time is typically 0.5 to 4 hours. The material to be treated may be, for instance, material, obtained from a formic-acid-based pulp cooking process, containing cellulose and/or lignin.

Abstract: The invention relates to a method of producing pulp with a high brightness using single-stage cooking with formic acid, washing with performic acid and bleaching with oxidizing bleaching chemicals. In performic acid washing, the rapid formation and rapid reactions of performic acid (HCOOOH) are utilitized for modification of residual lignin. The method of the invention provides an ISO brightness exceeding 90% without a chlorine chemicals. The method can be applied to both herbaceous plants and wood.