Abstract: The present invention relates to a method of processing printed waste paper, in particular waste paper containing at least 80% newsprint or magazine paper by digestion, various cleaning steps, flotation or washing and disintegrating, the latter with a high consistency of at least 20%, and possibly bleaching. The invention is characterized by the fact that a final second disintegrating step, arranged possibly before a bleaching step, with treatment of the waste paper under strong kneading action of individual bar-shaped or block-shaped kneading elements of both the stator and the rotor of the disintegrating machine which are arranged in a kneading chamber thereof which is delimited by two concentric cylindrical surfaces, at temperatures between 20.degree. and 110.degree. C., and preferably 38.degree. to 65.degree. C., and with a specific power consumption of between 30 and 100, and preferably 80, kilowatt hours/ton oven-dried pulp.

Abstract: The invention concerns a process for the treatment of wastepaper, carried out for the most at a high consistency of at least 13% in the first stages, beginning the dissolution (soaking) and including a coarse sorting stage. The invention is characterized in that in the case of wastepaper containing a share of at least 40% of deinking wastepaper provided with printing inks the three first process stages, namely in this order of soaking, coarse cleaning and the further extensive dissolution of the wastepaper, take place at a considerable reduction of the wastepaper shreds to the usual speck size at a consistency of at least 13%, and the soaking under considerable addition of dissolving chemicals, and that the wastepaper including essentially all heavy contaminations, such as part of wood, glass, plastic or metal contained in the wastepaper, including pieces of metal straps of the wastepaper bales, is fed to the process.

Abstract: In a flotation system, the generated quantity of foam is determined and, independent thereof, process parameters which directly or indirectly affect the generated foam quantity are reduced in their quantity depending on foam quantity. This is brought about by reduction of specific substance flows and also such substance flows that circulate in a flotation system. Production waters used for dilution are partly replaced by fresh water. This precludes an excessive amount of generated foam from causing difficulties in the operation of a flotation system.

Abstract: An apparatus for pulping paper into a pulp suspension is disclosed. A vertical container has an upper paper pulping zone and a lower pulp diluting and outlet zone beneath the pulping zone. A narrowed despecking slot communicates between the two zones. A rotor in the container circulates and breaks up the paper in the presence of the liquid in the pulping zone. Ribs on the rotor cooperate with stators in the container for defining the despecking slot. A pulp suspension dilution water inlet communicates into the dilution zone. The outlet from the container also communicates from the dilution zone. A screen protects the outlet from the dilution zone against exit of large particles therethrough and vanes on the rotor clean the screen.

Abstract: A process and apparatus for preparing waste paper for reuse in a paper machine. Waste paper, water and de-inking chemicals are introduced to coarse pulping apparatus, and the coarsely pulped stock suspension is then thickened by filtration and treated in a reaction tower. The pulp is then thinned and passed through flotation apparatus to remove separated impurities, particularly printing inks. Water removed from the pulp in the thickening operation is passed through second flotation apparatus with the clean water therefrom being reintroduced to the apparatus.

Abstract: Apparatus is provided for reprocessing old paper in a series of flotation cells arranged one behind another, the suspension discharge 11 from the front cell being connected to the suspension inlet 8 of the following cell, each cell being provided with a stirring impeller 3, an air infeed device 9 and a foam outlet opening 12. The cells are provided by a substantially tubular body 1 which is horizontal or slopes gradually downward towards the rear, the tubular body being divided into a plurality of sections by partition walls 2 extending substantially vertically. Each section is provided with a suspension inlet 8, a suspension discharge outlet 11, a foam outlet opening 12, a stirring impeller 3, and an air infeed device 9.

Abstract: A process and plant for treating waste paper in which a beater is employed for rough-pulping the waste paper followed by a first sorting stage from which the separated-out foreign matter is processed further in a subsidiary circuit which includes a vibratory sorter for lightweight foreign matter and a hydrocyclone for heavy foreign matter, the fibers separated out during this further processing being returned again to the treatment process. In the first sorting stage, a sufficiently rigorous separation process is carried out to remove the greater part of the foreign matter, together with unpulped lumps of fibers, which is then passed to the subsidiary circuit in which it and half-stuffs still containing foreign matter, which have been sorted in the hydro-cyclone and in the vibratory sorter, are subjected together to a multi-stage further sorting and speck-removing process.