Manufacture of activated carbon from sized coal

Claim 1

An improved method of making granular activated carbon comprising (a) crushing and separating to a size in the range of 2 × 40 U.S. Sieve Series, a coal having an ASTM rank of High Volatile C Bituminous, Subbituminous and Lignite, and having greater than 10 percent by weight bed moisture and greater than 10 percent by weight oxygen content; (b) heating said crushed and separated coal in air at a temperature of from about 150° C. to about 215° C. for a period of from 30 minutes to 18 hours, whereby from about 1 percent to about 3 percent by weight of oxygen is added to the coal; and (c) activating the thus oxidized coal at a temperature between about 540° and 1,100° C. in a controlled oxygen atmosphere; wherein the improvement comprises the step of contacting the coal starting material with a mineral acid in amount and for a time sufficient to result in an activated carbon produced by the remaining steps which has significantly higher Iodine and Carbontetrachloride Numbers, followed by the step of removing said acid from said coal, said steps being carried out prior to heating said coal in air.