Abstract: An autoclave for pressure oxidation of a slurried material including at least one sulfide material, and a method. The autoclave includes a pressure vessel for receiving the slurried material. The pressure vessel includes compartments being arranged horizontally one after the another and separated by dividers. Each divider is provided with an upper edge or at least one opening that defines level of the slurried material in the compartment. An inlet is arranged for feeding oxygen-containing gas into the pressure vessel. An agitator arrangement is arranged for agitating the slurried material in at least one of the compartments, the agitator arrangement including at least an upper impeller and a lower impeller, the impellers arranged along a vertically aligned shaft. The upper impeller is arranged at a height above the mid-level of one of the compartments, and the upper impeller is an upward pumping axial or mixed flow impeller.

Abstract: A heatable and/or coolable roll, i.e. a thermo roll, of a fibrous web machine for the treatment of a fibrous web, is, for example, for pressing and/or calendering the fibrous web in contact, i.e. in a nip, between the thermo roll and a backing member which is in contact with the thermo roll or for drying or cooling the fibrous web on the shell surface of the thermo roll. A semi-finished product of a thermo roll is manufactured using a thermo roll.