granular activated carbon and method of preparation from coal quality bitumieux less attack by a dilute acid mineral

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 (H2SO4, H3PO4, 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 DEG C at 150 DEG C/hour in an atmosphere of air and nitrogen and by maintaining the temperature for 4 hours, next devolatilized by heating to 450 DEG C at 300 DEG C/hour in an atmosphere of N2 and the volatiles and by maintaining the temperature for 1 hour, and then activated by heating to 800 DEG to 900 DEG C in an atmosphere of N2 and steam and by maintaining the temperature for 4 to 5 hours. The activated granules have a surface area of 1050 to 1090 m2/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.