An autoclave in the form of a cylinder with an upper hatch and a bottom hatch, the autoclave being terminated with elliptical end caps on both sides and having an agitator placed inside it, characterised in that the autoclave (1) is inclined in relation to the ground plane by an angle of 3-8 degrees towards its outlet, an external jacket (3) in the form of a membrane forming an external pressure space is mounted on the cylindrical section of the internal pressure chamber (2) of the autoclave (1), the jacket being divided into at least two pressure-separated parts (4). Inside the internal pressure chamber (2) of the autoclave (1) a paddle agitator shaft (7) is mounted, capable of performing a clockwise rotation and a counter-clockwise rotation, wherein the agitator mounting arrangement is out-of-alignment in relation to the axis of symmetry of the autoclave cylindrical section (1) by a shift of the mounting of the geometrical axis of the agitator's shaft (7) along the y-axis in a planar geometrical system, and the size of the shift does not exceed 2/3 of the radial length of the cross-section of the cylindrical section of the internal pressure chamber (2) of the autoclave (1). Moreover, each of the agitator's paddies (8) has two shields (9), one for each of the opposite sides of the paddle (8), and each shield (9) is shifted in the agitator's axis of symmetry in relation to its paddle (8) by a phase angle equal to 90°, and moreover, the shield height (9) does not exceed 1/3 of the height of the agitator's paddle (8).L'invention concerne un autoclave ayant la forme d'un cylindre muni d'une trappe supérieure et d'une trappe inférieure, l'autoclave étant terminé par des bouchons d'extrémité elliptiques des deux côtés et un agitateur étant placé à l'intérieur de l'autoclave, caractérisé en ce que l'autoclave (1) est incliné par rapport au plan de sol d'un angle de 3 à 8 degrés vers sa sortie, une chemise externe (3) ayant la forme d'une membrane formant un espace de pres
