Abstract
Sludge arising from physico-chemical treatment of industrial waste waters can be used as a component of clinker meals in cement plants.
The material on which the present experimental work is focused was obtained from industrial sludge poor in organic matter and rich in aluminium, iron and heavy-metal hydroxides. The metals are rendered inert by cement-based binders in full compliance with the current Italian provisions. The material was checked to verify that its components comply with the acceptability limits established by the users, and to assess the level of pollution produced at the processing site. The eluate obtained with CO2-treated water from the treated material does not show appreciable release of heavy-metals. Emission values at the chimney of the cement plant depend on the effectiveness of the gas filtering system. The addition of treated industrial sludge to kiln feed does not have an appreciable effect on the cement-plant chimney dust, and reduces operating cost, without affecting the properties of the product (clinker) and the plant's operating stability.
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