Recycling and immobilization of zinc extraction residue in clay-based brick manufacturing

Abstract

This study is related to the evaluation of zinc extraction residue, which is released in large quantities in the zinc metal production process and threatens environmental health, as an alternative raw material in the manufacturing of clay-based bricks. Bricks containing zinc extraction residue (5%–40%) were prepared and sintered at 900 °C, 1000 °C and 1100 °C. Fired brick specimens were characterized in terms of environmental risk, physical and mechanical properties. Sintered bricks at 1100 °C exhibited the different behaviors than others due to the vitrification phenomenon. Compared to the sintering temperatures, the compressive strength (39.22 MPa) and bulk density (2.31 g/cm3) of samples with 40% ZER at 1100 °C were higher than specimens at 900 °C and 1000 °C, while the porosity (3.1%) and water absorption (1.3%) values were lower. The solubility values of all metals, except for Pb, for all fired bricks with ZER at 900 °C, 1000 °C and 1100 °C are below the limit values according to TCLP standard. However, Pb could only be immobilized (<5 ppm) in ceramic body at 1100 °C for all additive rates. Pb release is within acceptable limits up to 10% (3.528 ppm) and 30% (4.989 ppm) ZER addition at 900 °C and 1000 °C, respectively. Experimental findings demonstrate that reuse of zinc extraction residue in the brick and ceramic manufacturing contributes to the improvement of product properties and immobilization of heavy metals.