Abstract: A method and system is used for removing foreign particles, e.g., printing ink particles, from an aqueous fibrous suspension, in particular recovered paper suspension. The method includes dividing the suspension in a fractionation into a fine fraction, in particular short-fiber fraction, and a coarse fraction, in particular long-fiber fraction. Both of the fractions thus formed are then treated in respectively differently operated flotations in order to carry away the foreign particles in the flotation foam. The parameters and apparatuses used of the two flotations can be optimally adjusted thereby to the conditions present in the individual fractions.

Abstract: Process for dissolving used paper including adjusting a content of solid particles of used paper to a range between about 15 and 35%, kneading the used paper with a specific work of at least about 10 kWh/t, diluting the kneaded used paper to a content of solid particles below about 6%, separating non-fibrous contaminants with wet screening, adjusting a solid material content to less than about 3%, and separating heavy particles with at least one hydrocyclone.

Abstract: Process for dissolving used paper including adjusting a content of solid particles of used paper to a range between about 15 and 35%, kneading the used paper with a specific work of at least about 10 kWh/t, diluting the kneaded used paper to a content of solid particles below about 6%, separating non-fibrous contaminants with wet screening, adjusting a solid material content to less than about 3%, and separating heavy particles with at least one hydrocyclone.

Abstract: The process targets the removal of interfering materials from an aqueous fibrous material suspension, especially if this is produced from recycled paper. Thereby interfering materials, such as printing ink particles, small synthetic particles, or sticky contamination, are eliminated by flotation in a particularly advantageous manner. In accordance with the invention, the combination of low-intensity and high-intensity flotation is undertaken, whereby the low-intensity flotation generally works in the gravitational field and the high-intensity flotation in a centrifugal field.

Abstract: A process for increasing a degree of whiteness of paper pulp may include bring paper fiber pulp, which may at least partially include printed waste paper, into a suspension with water. The suspension may be mixed with bleaching aids and bleaching chemicals. The bleaching chemicals may preferably contain molecular oxygen. Intensely mechanically treating the pulp, e.g., at at least 20 kWh/to, prior to bleaching the pulp suspension. The bleaching period may take at least 10 minutes, with a pressure above the atmospheric pressure being exerted during the bleaching. After bleaching, a major portion of remaining color print particles may be removed from the bleached pulp.

Abstract: To remove disturbing wax particles and for increasing the specific volume the short fiber fraction is subjected to a thermal treatment, especially by application of water vapor or steam, in a heater, such as a worm heater throughout a defined residence time and a defined temperature. With relatively low energy expenditure the distrubing wax particles are eliminated in such a manner that no wax spots or speckles can be discerned in the finished product. The specific volume of the short fiber fraction is appreciably increased while obtaining a predetermined strength.

Abstract: The method of dispersing a material containing waste paper by means of a dispersion apparatus and a dewatering machine, renders possible performing the material dispersion operation at essentially constant specific dispersion work even when encountering fluctuations of the raw material to be dispersed and of the dispersing process itself. For this purpose there is provided a regulating system which, with the aid of measured values or magnitudes derived from the dispersing process and predeterminate processing relationships, controls the addition of diluting water to the material to be dispersed at a location upstream of the dispersion apparatus.

Abstract: The bleaching chemicals are added to the pulp immediately after heating of the raw pulp thickened to more than 20% by weight and immediately prior to a dispersing process. This is carried out in a high-speed, high-efficiency disperser, where the heated, thickened pulp is forced through a plurality of narrow slits in a disperser lining and is exposed to strong shearing, impact and kneading stresses. In this way, the dispersing process is reduced to a time period less than 3 seconds, preferably about 1 second or less. As a result, the total time required for reductive bleaching is reduced to less than 15 seconds and no further measures are required for displacing and excluding air from the system. The method can also be advantageously used with oxidative bleaching at reduced reaction time requirements. A high dispersing temperature in the region of 40.degree. C. to 110.degree. C., preferably about 95.degree. C.

Abstract: A dispersion apparatus for the preparation of waste paper comprises fittings arranged within a housing and composed of a rotor containing ring-shaped concentric rows of teeth and a stator containing ring-shaped concentric rows of teeth. For the removal of the dispersed substance or material an additional rotor ring containing a number of transport teeth is mounted upon the rotor and an additional stator ring is mounted upon the stator. The stator ring possesses an opening above the discharge chute or portion of the apparatus which extends through an angle of about 90.degree.. The apparatus composed of the rotor ring and the transport teeth and the stator ring containing the opening renders possible removal of the dispersed substance or material, without altering its consistency and without there occurring cooling of the processed substance or material.

Abstract: To fractionate fiber stock there is used a sieve device which can be constructed in the manner of a secondary stock pulper or fiberizer, yet contains a sieve having a hole size in a range of about 0.8 to 2.4 millimeters diameter. The fiberizer contains a rotor driven by a drive motor and equipped with arms movable around the sieve. At the side of the sieve confronting the rotor there is located a closed long fiber chamber with which merges the infeed line for a cleaned fiber stock suspension which is obtained from waste paper. At the same time a long fiber line leads out of this long fiber chamber into a long fiber vat or container. Behind the sieve there is located a short fiber chamber from which leads a short fiber line to a short fiber vat or container. In at least one of the lines there is arranged a throttle element which is actuated as a function of a signal received from a power measuring device.

Abstract: At a fiberizer of a waste paper processing installation the rotational moment or torque is determined, for instance by measuring the drive output of a drive motor. In the presence of an increase of the rotational resistance of the rotor of the fiberizer there is brought about an intensification of the separation of rejects through a reject line and vice versa. For this purpose there are arranged in either the reject line or the good stock line, or at the same time in both such lines, throttle elements which are activated by a regulator. The regulator is controlled by a measuring signal of a measuring device which determines the electrical drive output of the rotor.

Abstract: The stain removal apparatus uses alternating rows of teeth between a rotor and the housing to clean paper pulp during passage of the paper pulp by the teeth. Check members are employed adjacent the teeth of the innermost row of teeth to preclude accumulations of material in front of the teeth. The check members are of the same thickness as the teeth at points adjacent the teeth while being shaped to merge into the rotor or housing at the end remote from the teeth.