Patent GB-1067312-A (GB)
Title: Improvements in or relating to methods of preparing pressure and temperature resisting bodies
IPC: C04B35/52
Filed: 1964-08-06
Abstract: In making a solid pressure- and temperature-resisting formed body of large dimensions in which particles of ore or of carbonaceous material, for example graphite, petrol coke or tar pitch coke, are bound by a bituminous binder which has been transformed into an infusible and insoluble state whilst retaining its binding properties, the particles and bituminous binder are mixed so that each solid particle is individually coated with a thin film of binder having a thickness preferably of about 1 micron, the resulting mixture is compacted by pressure so that the formed body contains a system of voids comprising 5 to 25% of the volume of the body and representing an intercommunicating capillary network distributed homogeneously throughout the body, and the body is exposed in a heating chamber at a temperature of from 150 DEG  to 300 DEG  C. to oxygen-containing gases, the gases being admitted and carried by a controlled flow throughout the network of the voids in the body until the transformation reaction, which proceeds in a zone in accordance with the gas flow, is completed. The transformation reaction, which preferably takes place at a temperature of from 190 DEG  to 220 DEG C., may comprise a process in which: (a) a tube is fitted into the centre of the body and is connected with either a suction system or a pressure system, a continuous controlled flow of oxygen-containing gases being carried by the tube either from the heating chamber through the body by suction or through the body to the heating chamber by pressure; or (b) the lateral surfaces of the body are coated with a gastight material, the body is placed in the heating chamber on a screen which is coated with a gastight material on those portions which protrude over the cross-section of the body and to the lower surface of which is connected either a suction system or a pressure system, and a continuous controlled flow of oxygen-containing gases is carried either by suction from the heating chamber downwardly through the body to the screen or by pressure from the screen upwardly through the body to the heating chamber; or (c) the body is placed on a screen in a pressure-resistant heating chamber into which oxygen-containing gases are passed to increase the pressure therein to about 3 atmospheres, this pressure is maintained preferably for about 15 minutes, the heating chamber is depressurized to atmospheric pressure, and the cyclic process is repeated at least once; or (d) the body is placed on a screen in a pressure-resistant heating chamber which is evacuated, oxygen-containing gases are admitted into the chamber and maintained therein preferably for about 15 minutes, and the cyclic process is repeated at least once; or (e) the pressurization treatment defined by process (c) and the evacuation treatment defined by process (d) are applied alternately. At the end of the transformation reaction, hot inert gases may be passed into the body to cool and to adjust the electrical conductivity of the finished body which may be used, when formed from petrol coke and bitumen, as a block anode for aluminium electrolysis.