GB899598A - Improvements in and relating to binding materials for carbon articles - Google Patents

Abstract

<PICT:0899598/III/1> In a process for producing a pitch suitable for use as a binder in the formation of carbonaceous bodies such as carbon electrodes a pitch obtained from the distillation of tar is mixed with carbon di-sulphide and heated to temperature of 350 DEG -450 DEG C., preferably 375 DEG -420 DEG C., at a pressure sufficient to inhibit the evaporation of the carbon di-sulphide. In a modification the carbon di-sulphide may be added to the tar during distillation. The amount of carbon di-sulphide added to the pitch or tar may be 2% by weight and the pressure may suitably be between 50 and 500 lbs. per square inch. The increase in pressure may be achieved by admitting an inert gas, e.g. nitrogen, under pressure to a chamber into which the heated pitch or tar and carbon di-sulphide is discharged. In the apparatus shown in Fig. 1 pitch is forced by a pump 11 through a coil 13 disposed in a heated chamber and then is discharged into the lower section 24 of a vessel 25 wherein it is mixed with pitch, previously treated by heating with carbon di-sulphide, admitted to section 24 from the upper section 26 of the vessel 25 through a connection 27. Mixed pitch from section 24 is forced together with carbon di-sulphide, admitted from line 57, by a pump 31 through line 32 and a coil 33 also disposed in the heated chamber 17. This pitch and carbon di-sulphide mixture is discharged by line 34 into the section 26 of vessel 25 maintained at a desired pressure either by admitting nitrogen through line 49 under control of a pressure controller 51 or by allowing escape of gas or vapour through line 54 under control of pressure controller 55. An amount of treated pitch equal to the amount of fresh feed is withdrawn from section 26 through line 36, cooler 38, flash pot 42 and line 48. In a modified apparatus tar to which carbon di-sulphide has been added is passed through a coil disposed in a heated chamber and the heated mixture is passed through a throttling valve into a flash chamber, the evolved vapours are fed to a fractionating column and the treated pitch is withdrawn from the flash chamber through a seal pot. In a further modification, a portion of the treated pitch from the flash chamber is mixed and circulated with the fresh tar feed. Specification 898,576 is referred