Granite extraction waste represents an interesting secondary material for ceramic production. Well evaluated in the formulation of red clay products, its influence on the porcelain stoneware formulations shows some gaps. For this reason, granite waste effects on technological properties were evaluated. In particular, residues from granite extraction for flux production were studied. Avoiding materials that can easily find a direct application, two different kinds of waste were selected: a coarser iron-rich material, coming from magnetic separation of crushed granite, and a finer one, derived from conveyance and abatement systems with bag filters. Both were characterized in terms of chemical-mineralogical composition, particle size distribution and thermal properties. Batches were formulated by partial substitution of feldspar, from 3 to 9 wt%. The technological behaviour of bodies as a function of waste content was assessed by simulating the industrial tile manufacture on a laboratory scale. Tiles of 10 cm × 5 cm × 0.5 cm were shaped by uniaxial pressure (40 MPa) with a hydraulic press, then dried (105 ºC overnight). The industrial process was simulated by fast firing in electric roller kiln at maximum temperature in the 1180-1220 ºC range (60 min cold-to-cold). The effect of waste addition was evaluated during the whole production process. Fired samples were characterized in terms of technological properties, colour, mineralogical composition, and microstructure evolution. Both mixtures show a progressive reduction of the maximum sintering temperature with waste amount increase. The formulation optimization led to reduce firing temperature, respecting the technological constraints for commercial products. A further increase of finer waste content worsened compaction during the shaping process and mechanical strength. Furthermore, the presence of micaceous particles, which persist as individual remnants after the firing process, may act as cracks initiation.