REDUCING FLY-ASH DEPOSITION BY PRETREATMENT OF BROWN-COAL - EFFECT OFALUMINUM ON ASH CHARACTER

The effect of pretreatment on the structure and the related fouling/sl agging behaviour of fly ash from brown coal has been investigated. Con densable sodium salts and low melting sodium silicates are known as fo uling and slagging materials. Experimental proof is given that less of such components were formed after treatment of Loy Yang brown coal wi th water and, particularly, with Al compounds. For the range of temper atures applied (1000-1400 degrees C) in a drop tube furnace, the quant ity of condensable salts generated was found to depend only on the amo unt of sodium in Loy Yang coal. Aluminium had the effect of reducing t he sodium level by ion exchange and thus the formation of fouling ash components. The stickiness of sodium silicates from this coal was also shown to be reduced by aluminium.