GB283573A - Improvements in and relating to the activation of carbon by means of gases - Google Patents

Abstract

283,573. Soc. de Recherches et d'Exploitations PÚtrolifÞres. Jan. 14, 1927, [Convention date]. Carbon. - In activating carbon by means of gases at high temperatures the carbon is impregnated or mixed prior to or during activation with an agent having ignifuge or fireproofing properties and being fusible or adapted to give rise to fusible compounds at the activating temperature in an amount not exceeding 5 per cent by weight. The carbonaceous material treated may be in the raw state, or wholly or partly carbonized or activated and may also be naturally or artificially agglomerated. The agent may be added in solution form by atomizing it into or mascerating it with the carbon, or in a dry powdered condition. The impregnating agent may be phosphoric acid, alkali phosphates, boric acid, borate, carbonate, bisulphate, or silicate of soda and caustic soda. To produce a moulded activated carbon, the carbon, active or inactive, is, ground, mixed with a binder such as sugar, bisulphite cellulose liquor, coal tar, wood tar, oxidized tars, dextrin, algine. gum arabic, iron gels, alumina or calcium sulphate, and a small amount of the fireproofing agents mentioned above, alone. or together, is added to the paste obtained and the material moulded, dried, calcined, and activated. In another method, carbon impregnated or agglomerated with organic substances, coked, and ground, is reagglomerated, the impregnating agents being added at either or both agglomerating &c. treatments, and the material after finally drying and calcining is activated, and may also be coated according to the process of Specification 261.692, giving a carbon or high density and strength. The ash content of the carbons may be reduced by washing before or after activation. Specifications 216,761, 279.104. and 291,725 are referred to. The Specification as open to inspection under Sect. 91 (3) (a) comprises also the addition to the carbon to be activated of agents, having little or no fireproofing properties, which are infusible or volatile at the activation temperature. To obtain a light, black and soft decolourizing carbon, wood charcoal is impregnated with traces of ferric chloride, zinc chloride, or hydrochloric acid, or is washed with water to remove ash before activation. The ash content of the activated carbon may be reduced by volatilization at high temperatures. In some cases the ash content of the primary material may be increased. This subjectmatter does not appear in the Specification as accepted.