Reimpiego di residui idratati della combustione del carbone in letto fluido come materiali desolforanti a base di ettringite

Fluidized bed combustion wastes, whose disposal and utilization is made difficult by their high quantity and low quality, can be conveniently re-introduced in the reactor and employed as desulphurizing agents, when submitted to a previous controlled hydration treatment. It has been found that ettringite, one of the hydration products, can give an important contribution to the desulphurizing ability of such hydrated wastes. Sulphation tests, made in a laboratory scale fluidized bed reactor, have shown that the desulphurizing action of a synthetic ettringite is better than that of a commercial limestone: the relative activity index is always favourable to ettringite and it is varying from 4.7 to 1.9, respectively between the start and the end of the sulphation tests. During hydration tests, carried out at 70°C up to 4 days, on industrial fluidized bed combustion wastes, ettringite has been obtained as main hydration product. Conversion degrees towards ettringite, comprised between 0.35 and 1.00, have been reached