Abstract: The present invention relates to a method of processing white liquor obtained from the causticization stage of a pulp mill. According to the method, the white liquor, which principally contains sodium hydroxide (6) and sodium sulfide, is oxidized into polysulfide liquor (3), whereby the sodium sulfide is oxidized most advantageously with the help of a catalyst and an oxidizer such as air substantially into sodium polysulfide (7) and sodium thiosulfate. The method according to the invention is characterized in that the sodium hydroxide (6) contained in the white liquor is separated from the white liquor prior to the oxidizing step or from the polysulfide liquor (3) after the oxidizing step either entirely or partly by means of a diffusion dialysis process (4). The invention is further characterized in that the sodium hydroxide (6) separated from the white liquor is returned to the chemical circulation of the pulp mill.

Abstract: The present invention relates to a cover (4) of a product package to be heat-sealed on the mouth of a product package and extractable therefrom when opening, and a method for manufacturing same. The cover is appropriate particularly for dosage packages of foodstuffs, such as milk, yogurt, juices and fruit syrups, desserts, etc., or for drug packages. The cover is made of paper (5) which is provided with polymer coating layers (6) on the undersurface, comprising a formally polymer binding agent layer and a heat-sealable polymer layer of an oxygen-tight, non-puncturable support layer, enabling extraction of the cover when opening the package. The essential feature in the invention lies therein that the support layer includes, as described above, a polymer component of high degree of crystallization and amorphous polymer component, wherewith the curling of the cover is prevented. Production of the cover (4) is accomplished with simultaneous extrusion of the polymer layers (6).

Abstract: The invention relates to a multi-layer product, in particular for producing containers, comprising a layer formed of a fiber-based packing material on one surface of which a gas-tight multi-layer plastic coating is arranged. To prevent the formation of microholes, the gas-tight multi-layer plastic coating is formed of superposed 1-4 g/m.sup.2 barrier plastic layer, 1-4 g/m.sup.2 binder layer, and surface layer of a heat-sealable polyolefin material having sufficient thickness for liquid-tight heat sealing, so that the barrier plastic layer is the closest of said layers to the fiber-based packing material layer.

Abstract: A method for producing a filter cigarette with tipping paper having improved lip release properties. Lip release chemicals are applied to one side of a base tipping paper during its manufacture in a papermaking process by surface coating, followed by manufacture of the cigarette using otherwise conventional apparatus and materials according to known procedures.

Abstract: The present invention relates to a method of processing white liquor (3) obtained from the causticization step of a pulp mill, in which method infeed white liquor (3) principally contains sodium hydroxide (6) and sodium sulfide (7). The method according to the invention is characterized in that the sodium hydroxide (6) contained in the white liquor (3) is separated from the white liquor (3) either entirely or partly by means of a diffusion dialysis membrane process (4). The invention is further characterized in that the sodium hydroxide (6) separated from the white liquor (3) is advantageously entirely returned back to the chemical circulation of the pulp mill.

Abstract: The invention concerns a method for the treatment of the spent liquors obtained from pulp production processes in the wood-processing industry, in which method the waste obtained from a chemical cooking process and that obtained from a mechanical process are merged for joint treatment. The chemical process may be e.g. a sulphate process and the mechanical process e.g. a chemi-thermomechanical process (CTMP), and the invention presupposes that the facilities for these processes are located close by each other, suitably within the same industrial complex. The essential feature of the invention is that the spent liquor of the CTMP is used as wash water in counter-current washing of the pulp obtained from the chemical process.

Abstract: The invention relates to a method for manufacturing a paper or cardboard product and to a product manufactured by the method. According to the invention, a cellulase enzyme is added to the product during manufacturing, said enzyme causing the product to decompose when exposed to moisture. The enzyme can be introduced into the product in connection with surface sizing, pigment coating or calendering, or it can be added in the form of a solution which is separately applied to the product in the dry end region of the paper or cardboard machine. Experiments have shown that a product manufactured as taught by the invention can be provided with a plastic coating without risk of destroying the enzyme. Cardboard produced by the method of the invention can be used in the manufacture of packages for liquids, of packing boxes or disposable containers, the cellulase enzyme serving to promote decomposition of the products after they have been brought as waste to dumping areas.

Abstract: A packing arrangement for sealing the outer surface of a rotary, drum-like object, such as a washer used in manufacturing cellulose, with a non-rotating annular packing, which is most advantageously composed of one or several side-by-side packing fillets, e.g. braided packings, the arrangement including a circular packing body which together with the rotating drum surface, defines a space in which the packings have been installed. The drawback encountered in existing arrangements is wear of the packing, and consequent leakage. In the packing arrangement of the invention, this has been solved in that the packing body is, at least in its radial direction, elastically supported so that, as the drum-like object rotates, the packings yield to the movements of the drum surface arising from radial displacements of the drum.

Abstract: An apparatus for washing cellulose, wherein the cellulose is conducted through between a rotary drum and a stationary shell encircling it, in the form of a layer supported by the permeable mantle surface of the drum. The principle of operation of the apparatus is: conducting washing liquid through the shell, through compartments located under the mantle surface of the drum and serving as washing liquid collectors, and through a valve system composed of a rotary part associated with the drum and a stationary part placed thereagainst, several times through the cellulose layer so that when the apparatus is operating the washing liquid at the same time moves in the direction opposite to the direction of rotation of the drum, stepwise, through the apparatus.

Abstract: The invention concerns a causticizing procedure by which from soda liquor derived from a sulphate cellulose digesting process and from unslaked lime is produced white liquor for reuse in the digesting process, over lime slaking and a subsequent causticizing reaction proper. It is essential in the invention that the lime slaking is carried out using white liquor, whereafter the causticizing reaction proper is allowed to take place between the slaked lime and soda liquor combined therewith. The requisite white liquor is obtained by recirculating part of the white liquor produced by the causticizing process, to the slaking step, where it either completely or partially replaces the soda liquor employed in prior art. By using white liquor, one avoids the foaming, interfering with the process, which is encountered in the slaking step.

Abstract: In a procedure for filtering lime sludge meant to be regenerated to lime. Lime sludge is produced in the causticizing process in a sulphate cellulose mill, where it can be reused after regeneration to lime. In the procedure, lime sludge suspension is filtered on a filter drum in continuous rotation by depositing lime sludge on the drum and detaching part of the superficial layer of the lime sludge on the drum with a scraper so that the deeper lime sludge layer on the drum, which by-passes the scraper, serves as filtering medium for the superficial layer that is detached (as a so-called pre-coat).

Abstract: A drum press with a rotating dewatering drum, inside which is eccentrically located a press roll of which the outer surface together with the inner surface of the dewatering drum defines a press gap compressing mass, such as bark, and in conjunction with the dewatering drum a removal screw is provided which detaches the mass that has been pressed to adhere to the inner surface of the dewatering drum and removes it for the next treatment step. The portion of the removal screw which is used to detach the pressed mass comprises a separate screw section removably disposed on the shaft of the removal screw and which is replaceable with ease.

Abstract: The invention concerns a procedure for recovery of soluble carbohydrates present in wood, in connection with the alkaline cellulose digesting process. According to the invention, recovery of carbohydrates takes place at the initial phase of the cellulose digesting process, where the digesting solution contains dissolved polysaccharides in abundance, while the content of polymeric lignin in the solution is low. A situation like this exists at the stage when the digesting solution has not yet reached the temperature at which the digestion process mainly takes place. As taught by the invention, the carbohydrates are recovered by conducting digesting solution to an ultrafilter, which separates the carbohydrates therefrom, and by returning the filtered solution to the cellulose digestion. The carbohydrates that are obtained may be used e.g. in the manufacturing of sugar alcohols, or as raw materials for biotechnical processes.

Abstract: Apparatus for clearing the blocked reject end of a vortex purifier without interrupting the operation of the vortex purifier, the apparatus includes an opening device for detaching the bottom plug of the reject end of the vortex purifier and an exit aperture for conducting off the reject of the vortex purifier. For enhancing the operation of the device of this type known in prior art, a valve is provided connected to the reject end of the vortex purifier for the duration of opening the plug, and that the device extending through the valve can be removed and replaced with a cleaning member, with the aid of which the blockage remaining in the reject end in spite of the removal of the bottom plug can be cleared.

Abstract: A twin hydrocyclone used for instance in cellulose and paper mills for purifying pulp suspension, the twin hydrocyclone consisting of two hydrocyclones mounted with their larger ends against each other and having one common infeed connector and one common purified fraction discharge connector. The hydrocyclones of prior art have the drawback of complex design and of division of the feed flow causing disturbances in the feed flow in view of the hydrocyclone's operation. The twin hydrocyclone, meant to solve these problems, is characterized in that the feed flow from the common infeed connector of the hydrocyclones is directed to each hydrocyclone as a separate feed flow by means of a helical member the helices of which constitute, in each hydrocyclone, feeding ducts confined by the walls of the hydrocyclones.

Abstract: The present invention concerns the measuring of a silicon coating on paper or cardboard moving in the form of a continuous web and which may as fillers contain substances containing silicon such as kaolin, or aluminum silicate. By x-ray radiation from a primary radiation source (3) and passing through the web is excited the characteristic x-ray radiation of an element, in a secondary radiation source (7) on the silicon coating side of the paper web (1), having a higher ordinal number than silicon (Si). The exciting radiation is sent obliquely against the surface of the paper or cardboard, whereby the irradiation of the surface is accentuated and the characteristic x-ray radiation of the silicon in the silicon coating can be excited. The exciting radiation also partly excites the silicon in the filler, but in this case it will be accompanied by the characteristic x-ray radiation of the metal associated with the silicate, such as aluminum in the instance of kaolin.

Abstract: The present invention seeks to provide a method in which the soda lye obtained as a result of cellulose cooking process and unslaked lime are used for producing white liquor which can be re-used in the cooking process. In this method, the heat released by the slaking of lime with soda lye is recovered by a high pressure slaking process wherein the heat is transferred, either to the steam separating from the lye, which steam is then led to the desired application, or to some other medium to be heated. The present invention is characterized in that the soda lye to be causticized is divided into two parts, one of which is used for the slaking of lime by adding to it all the unslaked lime needed for the causticizing process, and that, following slaking, the two volumes are brought together for the actual causticizing reaction involving the total amount of lye needed. The present invention provides the advantage that the amount of lye needed is smaller, and so the temperature can be increased.

Abstract: The present invention concerns a floating bed reactor which is used for biological purification of fibre-containing liquid suspensions and for simultaneous clarification. The reactor comprises a floating bed (8) composed of finely divided particles floating in an ascending flow, above it being formed a fibre agglomerate layer (9) which binds to itself fibres present in the suspension being treated. What is essential in the invention is that the removal of fibre agglomerate from the reactor has been arranged with the aid of an open-top collecting vessel (11) placed in the reactor and disposed to collect fibre agglomerate in itself so that the top margin of the agglomerate layer (9) positions itself in the reactor substantially on level with the top end of the collecting vessel. The agglomerate then moves into the collecting vessel (11) by effect of a trailing vortex, for the generation of which the top end (13) of the vessel is bordered by a flow guiding member projecting laterally therefrom, or encircling it.

Abstract: The present invention concerns a feed and accept duct system (4) for hydrocyclones (1), comprising common feed and accept ducts (7,8) which have by connecting tubes been connected to the parallel hydrocyclones. This type of construction is used, for instance, in purifying fiber suspensions, in which process the suspension is fed into the hydrocyclones (1) and the purified suspension is removed therefrom as a so-called accept fraction into the accept duct (8).

Abstract: A filter press for the thickening of cellulose pulp or sludge in which the filter press is furnished with a feedbox to lead the sludge suspension to the wire. In order to increase the capacity of filter presses or the like, the sludge to be dried can be fed through a feedbox in accordance with the invention, in which box there is at least one surface penetrating the liquid to facilitate thickening of the sludge suspension before it is lead to the filter press wire.