Abstract: A process for the calcination of raw gypsum in a heatable extruder, wherein the raw gypsum is feed into the extruder and heated to a temperature of from 150° C. to 350° C. to thereby convert the raw gypsum to calcined gypsum with a content of calcium hemihydrate of at least 50 wt.-%. By using a heatable extruder for the calcination, calcined gypsum with a high content of calcium sulphate hemihydrate and low residual amounts of the respective dihydrate and anhydrite can be obtained. The present invention further concerns a system, which is adapted to such preparation of calcined gypsum and includes an appropriate heatable extruder and the use of a heatable extruder for the calcination of raw gypsum.

Abstract: An extruder, preferably for calcining and extruding raw gypsum, including a calcination zone and a mixing zone, wherein the extruder is optionally configured to capture and/or retain water liberated in the calcination zone, apparatuses and processes employing such extruders and respective uses.

Abstract: A tool and a method are described for sheathing an elongated product available by the measured length, in particular in the form of a fiber or a fiber bundle, with at least one thermoplastic layer, with a wetting unit comprising at least one contact zone that can be filled with a flowable thermoplastic, through which the elongated product can be guided for the purpose of wetting with the thermoplastic in the form of a continuously progressing strand. The invention has a first feeding area for the elongated product and a second feeding area for the thermoplastic to emerge into the at least one contact zone. The contact zone comprises at least one outlet area and has a means is provided along the second feeding area, by which the thermoplastic can be introduced, subject to pressure, into the contact zone in the direction of the outlet area.