Effects of different reaction conditions on the free radicals in coal

In order to discuss the effects of different reaction conditions on the free radicals in coal,according to the mechanism of free radical reactions of in spontaneous combustion of coal,the variety of concentration of free radicals in coal was studied by electron spin resonance(ESR) spetroscopy during the process of fragmentizing,low-temperature oxidizing and ultraviolet radiating.The results show that different reaction conditions such as fragmentizing,low-temperature oxidizing and ultraviolet radiating are able to form new free radicals in coal,are able to influence the concentration of free radicals in coal.The smaller coal size,the higher the concentration of free radical in coal is.The concentration of free radicals in coal tends to increase with increasing oxidation temperature,the concentration of free radicals in coal increases rapidly after 125 ℃.Under the same oxidation temperature,the longer oxidation time,the concentration of free radicals in coal is higher,but the increasing speed is slower.The free radicals in coal are also very sensitive to the ultraviolet.The concentration of free radicals in coal increases sharply just in 30 minutes at the beginning and in 5 minutes at the finishing ultraviolet radiation.