The feasibility of steel slag recycling was assessed through both laboratory tests and industrial trials on three different typologies of wastes and clay bodies. Important requirements were the slag size, that must be previously ground below 3 mm, and the magnetic susceptibility of the waste that must be as low as possible to avoid occlusion of electromagnets and extruder die. After firing, the slag was actually inertised, as no significant effect on soluble salts and elution was found. In particular, there was no indication of Cr6+ or Ni2+ mobilisation from the clay bricks. The use of slag is substantially possible for additions of 2-3 wt% without any particular hindrances of a technological nature. Additions of up to 5-6% seem to be practicable, despite a porosity increase and a reduction of the mechanical properties of both unfired and fired products. Larger amounts of slag are decidedly inadvisable due to detrimental changes in the chemical and physical characteristics of the products. 25 refs.
Primary author(s): Cunico L; Dircetti G; Dondi M; Ercolani G; Guarini G;
Source: Tile Brick Int.