Granular activated carbon manufacture from low rank agglomerating but not good coking bituminous coal treated with dilute inorganic acid

摘要

Granular activated carbon is manufactured from low rank agglomerating but not good coking bituminous coal by crushing and screening the as received coal to produce 8/30 mesh granules, which are treated with a dilute aqueous solution of inorganic acid to prevent fusion of the granules during subsequent devolatilization comprising: mixing the granules with the acid (H.sub.2 SO.sub.4, H.sub.3 PO.sub.4, HCl or mixtures thereof) at a concentration of about 1% to about 15% by weight, washing off the acid, drying the granules thoroughly and thereafter mixing the granules with about 5 to about 15% by weight of a carbonaceous binder such as coal tar pitch. The so treated granules are ground to at least about 65% by weight -325 mesh powder, which is compressed into shapes such as pellets of 0.5 inch diameter and 0.5 inch long under a pressure of 40,000 to 80,000 psi, and then granulated to obtain 6/20 mesh granules. These granules are first charred by heating to 250 C at 150 C/hour in an atmosphere of air and nitrogen and by maintaining the temperature for 4 hours, next devolatilized by heating to 450 C at 300 C/hour in an atmosphere of N.sub.2 and the volatiles and by maintaining the temperature for 1 hour, and then activated by heating to 800 to 900 C in an atmosphere of N.sub. 2 and steam and by maintaining the temperature for 4 to 5 hours. The activated granules have a surface area of 1050 to 1090 m.sup.2 /gram, an Iodine number of 900 to 1100, an ash content of 6 to 9%, an abrasion number 75 to 80, and an apparent density of 0.51 to 0.53 gram/cc, which properties make them suitable for use in water and waste water treatment and in other applications.