GB723190A - Improvements in manufacture of carbon black - Google Patents

Abstract

<PICT:0723190/III/1> An auxiliary hydrocarbon make in gaseous form is rapidly and uniformly mixed with a turbulent suspension of carbon black whilst the latter is passing through a zone of a reaction chamber downstream from a carbon-forming zone and while the suspension is still at a temperature in excess of that at which the auxiliary hydrocarbon make is decomposed, in a process in which a hydrocarbon to be decomposed is mixed with a turbulent stream of hot gases flowing through an elongated reaction chamber at a temperature in excess of that at which the hydrocarbons are decomposed to carbon black and the hydrocarbons are decomposed in a zone of carbon black formation by heat absorbed from the hot gases to form carbon black in suspension therein and a suspension of the carbon thus formed in the hot gases is continued through the chamber at high turbulence, is finally cooled and the carbon black separated therefrom, e.g. of the type disclosed in Specification 669,968. The molecular weight and aromatic content of said auxiliary hydrocarbon should be at least as low as and preferably lower than that of the main make hydrocarbon, and the proportion of the former should not exceed 25 per cent by weight of the main make hydrocarbons, proportions as low as or lower than 1 per cent being effective. Whilst the turbulent stream of hot gases may be longitudinally directed as disclosed in Specification 654,864, preferably in a rectangular furnace, the apparatus described in detail is of the type described in Specification 669,968, having blast burners constructed as shown in Fig. 2 wherein the hydrocarbon fuel is supplied by valve tubes 10 terminating short of the inner wall of the furnace chamber. Air is forced through the conduit 11, passes tangentially into duct 12 and thence through burner ports 8, preferably cut at an angle to utilize the whirling motion of the air in the duct. It is preferred that the blast flame gases should be of an oxidizing character. Examples are given in which the main makes were (1) a petroleum distillate (2) highly aromatic distillate oil and (3) a mixture of 75 per cent pressure tar i.e. heavy tar residue resulting from pressure distillation of petroleum, and 25 per cent aromatic distillate, the auxiliary make being in each case natural gas. Similar results could be obtained with undiluted pressure tar, the auxiliary make then being natural gas or a distillate oil of lower aromatic content. Details are given of the colour and oil absorption value of the carbon black produced, and of the properties of standard tyre tread compounds containing the carbon black.