Fly ash from a power plant in Gdansk, Poland is stockpiled at two dump site
s and contains an average of 15 wt% combustible residue, in the form of ver
y fine coke particles. If recovered, the coke could serve as environmentall
y friendly fuel or as a source of carbon-derived materials, and the ash cou
ld be utilized in the production of construction materials. Since the fly a
sh material is already wet, a flotation technique was proposed for separati
on and product recovery. The flotation tests were carried out in a 1-1 Denv
er-type flotation cell and in a 2 inch diameter air-sparged hydrocyclone (A
SH). The flotation concentrate from the air-sparged hydrocyclone contained
35% coke by weight on a dry basis, with a coke recovery to the concentrate
of 54%. Experimental results are discussed with respect to particle charact
eristics. (C) 1998 Elsevier Science Ltd. All rights reserved.