GB1467496A - Method of manufacturing activated carbon - Google Patents

Abstract

1467496 Activated carbon NORTH AMERICAN CARBON Inc 28 Oct 1974 46444/74 Heading C1A A hard, porous chemically activated carbon is made by forming granules of a mixture of (a) a particulate carbonaceous starting material containing at least 25% wt. of oxygen on a moisture and ash-free (MAF) basis, (b) a carbonaceous binder consisting primarily of C, H and O preferably having a C content less than 60% and a O content greater than 30% (MAF basis), e.g. a lignosulphonate or a polyvinyl alcohol and (c) an inorganic activating agent effective at elevated temperature to remove oxygen and hydrogen from (a) and (b) without any substantial removal of their carbon content and heat-treating the granules whereby they are simultaneously carbonized and activated. The carbonaceous starting material (a) is preferably ground to - 40 mesh (ASTM E-11 sieve) prior to mixing with the other components and may comprise wood, straw, peat or low rank brown coals. The hardness of the activated carbon may be controlled by varying the amounts of the carbonaceous binder material, an increased content leading to an increased hardness. The activating agent (c) may be ZnCl 2 or preferably H 3 PO 4 . The ratio of activating agent to dry basis carbonaceous materials is preferably at least 0À35 ; 1. The granulated mixture is suitably heat-treated at a temperature of 650‹ C. for up to 3 hours. The furnace atmosphere may be modified by the introduction of a sweep gas, e.g. air or steam. After the heat treatment the activated carbon particles are washed and dried. The particles have ball-pan hardness values as high as 97%.