Abstract: In a method for bleaching oxygen delignified cellulose-containing pulp such as sulphate, sodium and sulphite pulps with ozone and peroxide, the ozone treatment takes place at two stages, the alkaline solution which is added subsequent to the ozone treatment includes peroxide and complex formers, and 55 to 85% of the total amount of chemicals is added at the first stage.

Abstract: When treating refined mechanical pulp and thermo mechanical pulp with ozone, it is of great importance that the process be carried out at the most favorable conditions and with a minimum consumption of energy. According to the present invention the pulp is refined to a freeness value of at least 200 csf in a first stage refiner from which the pulp is passed to a high consistency ozonizer and maturation reactor for a time limited to maximum 30 minutes. From the reactor the pulp is passed direct to a second stage refiner, the pulp then having a solids content of approximately 8-10% and an alkaline value in the range of 7-10.

Abstract: In a reactor plant for treating finely divided bulk material an acid bulk material or pulp having a solids content of approximately 35-50% is conveyed to a combined high-consistency ozonizer and maturation reactor as a substantially vertical pulp column forming a gas blocking means. In the transition area between the ozonizer and the maturation reactor the finely divided and ozonized pulp which has a very acid pH-value is mixed with chemicals to a pH-value of approximately 8-11 and to a solids content of approximately 15-20%, at which solids content the alkaline pulp in the form of a continuously advancing column is subjected to a maturation process which terminates at a pH-value of the pulp of 6-7.

Abstract: A disc press for continuous pressing of aqueous or suspended pulp for fractionating the pulp in a liquid fraction and a dry substance fraction, comprises two plane parallel pressing discs mounted for rotation about a shaft and having strainer plates which haul the pulp therebetween by friction. The press also comprises inner and outer pressing means extending between the pressing discs and together with the latter define a curved pulp passage which in the transport direction has a varying cross section and constitutes a filling or dewatering zone, a pressing zone and a discharge zone. The passage zones of the pulp passage combined extend throughout an angle which is less than 360.degree., and the filling or dewatering zone has an approximately constant cross section. The subsequent pressing zone (B) has a uniformly decreasing cross section, the centerline of the pressing zone following an arc having an approximately constant radius about the axis of rotation.

Abstract: A method and apparatus for treating finely divided fibrous pulp with gas without overpressure in a continuous process. The bulk material is substantially continuously supplied to a reactor having one or more supporting floors having apertures of a shape and size which allow the finely divided material to form bridges across the apertures, said apertures also permitting a continuous flow of gas through the bulk material. The bulk material proceeds through the reactor as a consequence of the bridges being broken by breaking arms sweeping along the upper surface of the supporting floors.