Granular activated carbon - by heating mixt of carbon-contg raw matl esp wood lignosulphonate or polyvinyl alcohol binder and phosphoric acid

摘要

Granular activated carbon materials are made by (1) mixing (a) a carbon-contg. raw material with an oxygen content of >=25 wt. % on a moisture- and ash-free basis, chosen from comminuted wood, straw or low quality coal, (b) a carbon-contg. binder chosen from a lignosulphonate and a polyvinyl alcohol which is soluble or emulsifiable in water or a phosphoric acid soln., such that the bonder contributes >=24 wt. % of the carbon content of the original mixt., and (c) an amt. of H3PO4 sufficient to give a ratio of 100% H3PO4 to dry solids in (a+b) of at least 0.35:1, (2) forming the mixt. into solid granular shaped particles of the required size and (3) heat treating the particles for a pre-determined period at is not >650 degrees C to give activated carbon particles with a ball hardness of >=85%. Prods. have greater hardness and wear resistance than known activated carbon prodts. made by steam- or chemical activation processes. (a) is spec. milled wood flour and (b) provides >=28 wt. % of the carbon content of the compsn. to give a prodt. with a ball hardness of >=90%.