Process and System for the Calcination of Gypsum
AssigneeKnauf Gips KG
InventorsRauno Baese, Raphael Geiger
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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.
Claims19
A process for the calcination of raw gypsum in a heatable extruder, comprising or consisting of the following steps:
- i) providing raw gypsum as a powder or as a paste;
- ii) feeding the raw gypsum into a heatable extruder having a calcination zone and optionally a mixing zone;
- iii) heating the raw gypsum in the calcination zone of the extruder, particularly to temperatures of between 150° C. and 350° C., to provide a calcined gypsum, wherein at least 50 wt.-% of the CaSO4 has been converted to calciumsulfate hemihydrate, while withdrawing crystal water from the raw gypsum, and
- iv) discharging the calcined gypsum from the extruder.
A system for the calcination of raw gypsum wherein the system comprises
- i) a feed unit to feed raw gypsum to an extruder;
- ii) downstream thereto, a heatable extruder having a calcination zone and optionally a mixing zone, wherein the heatable extruder preferably has a plurality of individual temperature setting elements;
- iii) downstream thereto, a retaining device, wherein the calcined gypsum is collected.
Dependencies are inferred from the claim text.