Inhibiting fly ash reactivity by adding N- and S- containing compounds

Abstract

The inhibitory effect of thiourea (TUA), ammonium thiosulfate (TSA) and amidosulfonic acid (ASA) on the reactivity of fly ash air was investigated using a thermobalance at different heating rates (5, 10 and 20 K min). A model fly ash (activated carbon + 50 wt% CuCl·2HO, pyrolyzed at 700 °C and washed) was used as carbonaceous material. Adding CuCl·2HO to the activated carbon led to an increased rate of decomposition with the air's oxygen. TUA and TSA behaved in a similar way, accelerating the decomposition of the model fly ash. ASA also accelerated the decomposition but to a lower extent. We postulate that the increase in decomposition rate is caused by a reaction between carbonaceous material and N and S-containing compounds. The formation of nitrogenated and sulphured compounds was confirmed by TG-MS. A kinetic model based on a single reaction of order 0.6 showed very good correlations with all the heating rates tested in oxidant atmosphere.

Sewage Sludge as Inhibitor of the Formation of Persistent Organic Pollutants during Incineration

“…Soler et al [35] also studied the mechanism implied in the thermal decomposition of model fly ash modified by the presence of N-and S-containing compounds. Specifically, the authors test the presence of thiourea (TUA), ammonium thiosulfate (TSA), and amidosulfonic acid (ASA) on the reactivity of fly ash air; however, the investigation was done using a thermobalance at different heating rates (5, 10, and 20 K min −1 ) and analyzing the evolved gases.…”

Estimation of Industrial Emissions during Pyrolysis and Combustion of Different Wastes Using Laboratory Data

“…Thiourea, ammonia thiosulphate and sulfamic acid have been extensively studied. Different authors 33,34 describe a drop of over 95% in emissions of chlorinated compounds when these compounds are present.…”