GB277987A - Improvements in the production and activation of carbon - Google Patents

Abstract

277,987. Daniels, J. S., (Assignee of Meeze, E. H.). Sept. 22, 1926, [Convention date]. Carbon.-Active carbon is produced from wood, peat, lignite, brown coal and other carbonaceous materials, alone or mixed, by destructively distilling at reduced pressure in the presence of steam or inert gases, or both, or of oxidizing and other active gases. The carbon is next cooled under conditions favourable to the occlusion of atmospheric oxygen, and may then be ground and treated with catalytic materials, and is finally subjected to a second heat treatment in which the occluded oxygen increases the activation of the carbon. The raw material is first heated under reduced pressure to 500-800 ‹C. in a retort preferably of metal, the volatile products, which may be withdrawn by the aid of a pump, being passed through a condenser. Steam, preferably superheated, is supplied to the retort. The pressure within the retort may be varied periodically through a large range. When the volatile products have been removed, pressure is returned to normal by reducing the exhaustion and continuing the injection of steam with or without the addition of combustion gases from without the retort. The carbon is allowed to cool in a water sealed vessel and is then crushed in a roller ball or tube mill, catalytic material in relatively small amount being added therein either in powdered form or as a solution atomized by steam &c. Compounds of zinc, magnesium, ammonium, cadmium, and tin are used as the catalysts, e.g. zinc and cadmium chlorides and zinc oxide mixed with ammonium chloride. The carbon may be graded at this stage. The final heating may take place in a fireclay retort, preferably horizontal or inclined, the temperature. employed being up to 1000‹ C., for example 850‹-1000‹ C. The finished carbon does not generally require treatment to purify it from the catalytic material, which may also be added at other stages, e.g. before the first heating. The active carbon may be obtained in granular or block form by starting with suitably porous raw material in granular or block form impregnated with catalyst. The heat treatments may take place in a single or in separate retorts, and may be operated continuously or discontinuously.