Self-heating characteristics of materials for producing activated carbon

Porous, granular or fibrous materials that contain oxidizable organic constituents often experience self-heating that leads to spontaneous combustion. Activated carbon is known to be prone to self-heating because of its high surface area. Experiments were conducted to identify factors likely to cause self-heating of materials for producing activated carbon. Spontaneous combustion and characterization tests were carried out on three materials generated from the South African Coalfields [coal slurry (SLY), coal discard (DIS) and run-of-mine fines (ROM)]. This study indicated that the higher amount of vitrinite and lower ash contents in sample ROM compared with the other two samples SLY (3.73) and DIS (3.72) could be the cause of its higher liability value (3.8). The potential of activated carbons produced from the material most liable for spontaneous combustion was also investigated. The activated carbons were prepared by KOH activation, and the results obtained indicated that the activated carbons can be used in several applications. The synthesized activated carbons were characterized by nitrogen adsorption isotherms and SEM characterization. Surface area exceeding 1000 m(2)/g was obtained for most of the activated carbons produced. The nitrogen isotherms and pore size distribution profiles confirm highly porous activated carbons consisting of micropores and mesopores.