Electrostatic painting residues as an alternative raw material for red clay industry.

In this study, the viability of using electrostatic painting residues--paint sludge--as a raw material to the red clay industry was investigated. Red clay-based ceramic masses containing electrostatic paint residues were formulated during the study. The clays were obtained from the Rio do Rastro deposit, in Gravataí, and were of the standard formulation used in industry. Different ceramic mass formulations with additions of 0.5, 1.0, 2.5 and 5.0 wt.% electrostatic painting residue in addition to a formulation with no residue addition (standard formulation), were evaluated. The samples were uniaxially pressed in a double-effect press and were fired in an electric oven at 900, 950 and 1000 degrees C. The firing at constant temperature lasted 8 h, and heating rate was 150 K h(-1). After processing the samples were characterized in terms of their physical and mechanical properties. Environmental compatibility was also considered by the evaluation of gaseous emissions and leaching and solubilization tests according to the Brazilian standards NBR 10.005 and NBR 10.006, respectively. The results showed that it was possible to produce ceramic materials containing electrostatic painting residues within their formulations.