Role of particle size in assessment of physico-chemical properties and trace elements of Indian fly ash

Abstract

In this paper, the effect of particle size on the physico-chemical, mineralogical, and leaching behavior of Indian fly ash was studied. Experiments were carried out to study the leaching of different elements such as Mg, Cr, Zn, Pb, Mn, Fe, Cu, Co, Mo, and Ni from Indian fly ash. During the experiments, the liquid-to-solid (L/S) ratio of the fly ash was taken as 9/1, 8/2, 7/3, 3/2, 1/1, and 2/3. The effect of four different particle size ranges (below 53, 53–75, 75–106, and 106–150 μm) of fly ash was analyzed. The ASTMD-3987 method was used to analyze the presence of trace elements from fly ash. In the ASTM D-3987 method, distilled water was used for extraction of leachate. Fly ash slurry samples were agitated in a lubricating type temperature-controlled Remi orbital shaker for a time duration of 18 hours with speed of 100 revolutions per minute (rpm) at a temperature of 25ºC. Distilled water does not save cost as well as being easily available. The leaching test of trace elements from fly ash was investigated at different pH conditions in order to predict the environmental effect from the ash disposal on the groundwater quality. Results revealed that pH of slurry suspension increases with increase in particle size. The pH value of fly ash slurries was negligibly affected by the decrease in L/S ratio for all particle sizes. Fine particles of fly ash produce a more harmful effect as compared to the coarser range of fly ash particles.