Abstract: A disc-type refiner wherein the means incorporating the refining surfaces are positioned in opposed, relatively adjacent, closely spaced relation and one thereof is formed to include at least one passageway through which steam created in the refining of material between the refining surfaces may be simply and quickly vented. A duct means is provided to receive and carry steam from the passageway to the exterior of the refiner housing, to facilitate use or disposal as and where desired. Means are included to control the amount of steam being vented and to maintain the venting arrangement on adjustment of the spacing between the refining surfaces. In the preferred embodiment illustrated, the invention features are incorporated in a double revolving disc refiner which, by reason of the improvements of the invention, may be operated under either atmospheric or pressurized conditions. In either case considerable benefit is reflected in the refining procedure and the quality of its end product.

Abstract: A disc refiner wherein the operating faces of its discs are arranged to have interdigited teeth disposed in radially spaced rows and to further have dams interposed between selected successively adjacent of said rows. The dams are characterized by being parallel to said rows and substantially coextensive therewith. Each dam is accordingly substantially continuous and each serves in the operation of the discs to block substantially all material moving across the face of the disc of which it forms a part and causes it to be deflected outwardly and to impact on the operating face of the opposing disc. The arrangement is such to insure that as the material the constituents of which are to be separated moves across the respective operating faces of opposed refiner discs it will be repeatedly thrown from one disc operating face to the other and in the process have imposed thereon a forceful separation of constituent parts.