Development Of Coloured Stoneware Bodies Through The Incorporation Of Industrial Cr/Ni Electroplating Sludge

Electroplating sludge (ES) is currently disposed in landfills and, because of its heavy metal content, poses serious threats to the environment and human health. However, ES might have potential use as colouring agent due to its high concentration of chromium and nickel. Thus, the present work aims at studying the effect of ES incorporation into stoneware bodies. The influence on the final characteristics of fired samples, ES amount and pre-treatment were analysed. It was found that stoneware pastes having uniform brownish hues can be obtained with only 3 wt.% of sieved (<212 mu m) ES. The obtained specimens have, once fired, the desired technical and aesthetical characteristics. Further, leaching tests confirmed the immobilisation of hazardous ES species in the ceramic matrix. Hence, it can be concluded that this waste can be used as colouring agent of stoneware pastes substituting commercial pigments and contributing to more sustainable consumption and production in the ceramic sector.