The stirring apparatus (10) comprises a stirring tank (12) containing a liquid (14), a stirrer (18) rotating in an axial direction in the stirring tank, and a security device. The rotation of the stirrer is carried out through a rotating environment using a rotational shaft (22) guided by bearings. The shaft is rotated through an annular space having a lower portion disposed below the bearings. A section of the lower portion is upper than the rest section of the annular space. The security device is placed around the shaft in the lower portion, and comprises a movable valve. The stirring apparatus (10) comprises a stirring tank (12) containing a liquid (14), a stirrer (18) rotating in an axial direction in the stirring tank, and a security device. The rotation of the stirrer is carried out through a rotating environment using a rotational shaft (22) guided by bearings. The shaft is rotated through an annular space having a lower portion disposed below the bearings. A section of the lower portion is upper than the rest section of the annular space. The security device is placed around the shaft in the lower portion, and comprises a movable valve comprising an upper side having a toric joint, which is present between the upper side and a lower side of the shaft, when the security device is in closed configuration. The valve is displaced inside a fixed ring, and has a revetment oriented towards the top. The ring has a revetment oriented towards the base. The revetments are opposite to one another and separated by an intermediate space, when the safety device is in open configuration, and are in contact with one another, when the safety device is in closed configuration. The travel of the valve is equal to a distance between the two revetments, when the security device is in open configuration. The intermediate space is filled with grease. The valve has an outer face and/or the ring has an inner face to slide against one another, when the security device is in closed configuration. The outer face of the valve and/or inner surface of the ring is coated with a coating and undergoes heating, so that the relative sliding of one against the other is facilitated.