Distribution and leaching behavior of sodium in Zhundong coal seam

The upper seam coal (US coal),parting and lower seam coal (LS coal) were sampled from Zhundong min- ing area. Chemical extraction experiments and dynamic leaching experiments were carried out to study the occurrence, distribution and leaching behavior of sodium. The results show that the content of total sodium in coal sample ( upper layer and lower layer sample) is obviously higher than that in parting. The content of water soluble sodium (H2 O-Na) is only 1. 37 mg / g,but which accounts for 82. 49% ,significantly higher than 65. 50% of US coal and 64. 35% of LS coal. The concentration of sodium ion fell sharply first,and then shows a trend of balance. The initial leaching rate of sodium in US coal is the highest. Shrinking core model shows that the reaction rate constants of leaching kinetics of the US coal,parting and LS coal are 0. 001,0. 005 and 0. 002 h-1 respectively. The relationship of leaching ratio of H2 O-Na is:parting>US coal>LS coal,and parting of which accounted for 99. 62% . After dynamic leaching experiment,the content of Na2 O in US coal and LS coal ash fell to 2. 67% and 2. 06% respectively,which are lower than the require- ments of stable operation in coal-fired boiler.