Innovative sintering process for ceramic tile fabrication using a ternary alkali agent to reduce temperature and enhance performance

The addition of a ternary alkali agent composed of sodium hydroxide, sodium aluminate and calcium hydroxide in the sintering process of ceramic tile fabrication was proposed. Sewage sludge acid-leaching residue and waste bottle glass were used as raw materials. The results indicated that the addition of 6 M sodium hydroxide, 6 wt-% sodium aluminate and 8 wt-% calcium hydroxide reduced the sintering temperature from 1100 °C to 750 °C and enhanced the performance of the produced ceramic tile. Under optimal conditions with an sewage sludge acid-leaching residue:waste bottle glass mixing ratio of 1:2, solid–liquid mass ratio = 2:1 (g/g), and sintering duration of 75 min, the produced ceramic tile achieved a bending strength of 6.5 MPa, bulk density of 1.61 g/cm³, water absorption of 12.5% and porosity of 12.5%. This study demonstrates that ceramic tiles can be produced through a cleaner process while simultaneously achieving waste valorisation of sewage sludge acid-leaching residue and waste bottle glass.