Abstract: The invention provides improvements in vortex separators for separating the rejects from the accepts in a particle-laden fluid, the separator including, in preferred embodiments, a replaceable inner wall lining minimizing maintenance costs while raising separating efficiency, and in addition, includes means for submitting the rejects to a size reduction process, an elutriation process, a dilution process, and a throttling process, all in one compact unit.

Abstract: The invention provides a method and apparatus for thickening centrifugally separable fractions by the steps of providing a pressurized stream of a liquid suspension medium containing a fraction separated centrifugally from any other fraction, causing the stream of the suspension to flow in the form of an annular helical vortical flow, passing the stream of the suspension through a restricted opening, allowing the stream of the suspension to expand into a larger volume contained within a converging confining zone converging in the direction of stream flow and towards the discharge zone having a restricted opening of a size smaller than the size of the first-mentioned restricted opening, regulating the flow of the stream of the suspension to form and maintain the stream as a first vortex of the suspension flowing towards the discharge zone whereby a portion of the suspension reverses direction in the converging zone adjacent the restricted opening of the converging zone and forms a second vortex flowing towards

Abstract: A process for the disposal of paper pulp mill sludge by incorporating the sludge in the digestion step of a wood pulping operation without detrimental effects on the quality of the pulp obtained. In one aspect, the sludge is surplus sludge which is obtained from a system which microbiologically purifies spent wood pulping liquor by aeration and sedimentation.

Abstract: An apparatus for obtaining rapid bonding of thermoplastic materials to themselves or other similar or different materials by means of a high velocity high temperature direct flame in combination with pressure. This achieves a sufficiently rapid treatment so that the properties of the materials are not substantially detrimentally affected. Thin laminates of highly oriented materials can be bonded without loss of strength characteristics.

Abstract: A method and apparatus for slitting a moving thermoplastic film. A rotating slitting roll, provided with a plurality of spaced-apart heated blades circumferentially arranged in a pattern, presses the film against a backing member while the film is under tension and in line-contact with the roll. The pressure and heat of the blades fusion-slits the moving film, which may then be stretched to spread the slits and in the case of orientable film to orient the film in the direction of stretch. The slits may be made in either the machine or cross-machine direction. Where continuous slits are made, tapes or ribbons are formed. Where the slits are discontinuous, an aperture film results.