Non-conventional stabilisation/solidification treatment of industrial wastes with residual powdered paints

Stabilisation/solidification technologies are widely used for rendering industrial wastes inert. In this study, residual powdered paints were applied to treat different types of industrial wastes by stabilisation/solidification: Fumes from steel-making process, sludge from coagulation/flocculation treatments and powders from brushing and polishing metallic objects. Stabilisation/solidification trials were performed both under static conditions and in motion. It was observed that the residual paints could polymerise well in 60 min at 120 °C. The addition of water during the treatment resulted in highly porous and friable materials and, therefore, is not recommended. The mixture between wastes and paint influenced polymerisation. Specific heating conditions needed to be tested for each waste, varying from 80 °C to 150 °C. Significant reduction on leachability after treatment could be reached in most cases. Reduction on chlorides release up to 92.0% were achieved. Contents of other elements on the leachates, such as copper, molybdenum, nickel, zinc and dissolved organic carbon, could also be reduced in percentages up to 96.9%, 97.6%, 98.8%, 95.7% and 96.9%, respectively. For some types of wastes, however, especially those containing high contents of copper and mineral oils, the treatment was ineffective. Polymerisation in motion apparently improved binding capacity, but tests with increased content of paints are recommended to reduce the release of dissolved organic carbon.