Process of reactivating contaminated adsorptive carbon

摘要

313,154. Metallges. Akt.-Ges. June 8, 1928, [Convention date]. Carbon. - Pulverulent to five-grained absorptive carbon is reactivated by converting it into moulded blocks with the addition of binding media if desired, and treating, under conditions in which relative movement of the pieces of carbon is avoided, with gaseous mixtures containing free oxygen, in amounts less than 8 per cent by volume. Under the conditions of treatment, a zone of actual activation is formed, which moves onward in the direction of flaw of the gases. The carbon may be preheated by superheated steam, hot air &c. The regenerating gas may be preheated to a temperature below 250‹ C., preferably 120-200‹ C. When the process has begun, the temperature of the gas may be reduced below that at which oxidation of the impurities begins, for example where mixtures of air and carbon dioxide are employed, the temperature may be reduced to normal level. The temperature in the raction zone is about 500-600‹ C. The oxygen may be mixed with steam with or without other gases, such as combustion gases. The carbon may be treated in a underlayer in a heat insulated container, the regenerating gases being passed upwards therethrough. An under layer of readily oxidizable material, e.g. carbon impregnated with substances of low ignition temperature, may be provided where the reaction does not commence at low temperatures. The process may be a continuous one, the carbon and the gases being in countercurrent flow. A preliminary purification off the carbon with solvents may be included, and if inorganic substances which are not readily oxidizable to volatile compounds are present, treatment with acids or alkalies followed by washing with water may be employed prior or subsequent to the actual reactivation step. Mixtures of carbon with other adsorbents, e.g. wood charcoal, fuller's earth or kieselguhr, may be treated. The moulded bodies, e.g. filter cakes, may be broken up into pieces of suitable size before treatment or may be treated as a whole by passing the gas over one or both sides of the cakes. Examples are given in the Specification of the regeneration of spent carbon from sugar and oi[ refining.