Process for passivation of reactive coal char

A continuous process for treating coal to form stable coal char by passivating the cast and then rehydrating and cooling the product thereof to prevent spontaneous ignition, the process comprising the steps of:

• a) pyrolyzing the coal by progressively heating substantially all of the coal to a temperature of about 537.degree. C. sufficient to vaporize and remove low end volatile materials from the coal and heating to a mild gasification temperature to form coal char and sufficient to mobilize at least a portion of high end volatile materials within the char and at least partially collapsed micropores within the char;
• b) cooling the coal char by about 100.degree. C. in about 20 minutes or less to demobilize the volatile materials within the at least partially collapsed micropores of the coal char and to pyrolytically passivate the coal char and form a char having about 14-22 wt % high end volatiles;
• c) conveying the char of step b) to a reaction vessel wherein a process gas having about 3%-21% by volume oxygen flows through the reaction vessel to at least partially fluidize the coal char and oxidatively passivate the coal by chemisorption of oxygen, thereby raising the temperature of the process gas and lowering the oxygen content of the process gas;
• d) monitoring the temperature and oxygen content of the process gas exiting the reaction vessel;
• e) progressively decreasing the temperature of the oxydative passivation within the reaction vessel from 200.degree. C. to 100.degree. C. in response to the temperature of the monitored gas;
• f) replenishing the oxygen content of the process gas flowing from the reaction vessel in response to the monitored oxygen content to contain about 3%-21% by volume oxygen;
• g) reintroducing the replenished process gas to the reaction vessel;
• and
• h) substantially simultaneously rehydrating and cooling the passivated coal char to form a stable coal char having about 5-10 wt % moisture.