Method and apparatus for mixing chemicals into fiber pulp

An apparatus for mixing chemicals into ligno-cellulose materials, comprising fixed substantially horizontal casing, rotatable means within the casing, the rotatable means and casing together defining a flow space surrounding the rotatable means for providing a pulp flow path through the apparatus, first inlet means for admitting pulp to be treated to said space adjacent one end of said casing, outlet means for treated pulp positioned adjacent an opposite end of said casing, the casing defining at least three different treatment sections between the first inlet means and the outlet means, the rotatable means in first of said treatment sections which is positioned closest to the first inlet means including transport means for transporting the pulp to subsequent ones of the treatment sections with increased pressure, second inlet means for the supply of chemicals to said flow space in said first of said treatment sections, one of said subsequent treatment sections being provided in said flow space with guide means fixed on said casing and guide means fixed on said rotatable means for forming, upon rotation of aid rotatable means, a pulp flow channel between an entrance and an exit of said one of the subsequent treatment sections, said guide means fixed on the rotatable means extends outwardly towards the casing and said guide means fixed on the casing extends inwardly towards said rotatable means, said guide means fixed on the casing alternates in position along the length of said casing with respect to said guide means fixed on the rotatable means along the length of said rotatable means, thereby providing a shearing of the pulp during mixture of the pulp with chemicals supplied through said second inlet means, and another of said subsequent treatment sections having a first part with means for imparting to the pulp in said flow space a retarding velocity in a flow direction of the pulp and a second part positioned downstream of said first part with means for imparting to the pulp in said flow space an accelerating velocity in said flow direction, thereby providing pulses consisting of compressions and expansion of the pulp and velocity variations in the flow direction of the pulp.