How can the paint coating on used beverage cans be efficiently removed?

In the aluminum recycling supply chain, used beverage cans are a highly prized raw material for secondary aluminum plants. If they are fed directly into the furnace for smelting without paint removal, the thin aluminum oxidizes rapidly into dross at high temperatures—resulting in high burn-off losses—and generates pungent black smoke and organic impurities that severely compromise the purity of the molten aluminum.

So, how exactly do industrial-scale operations remove paint from cans efficiently and in an environmentally friendly manner?

Currently, the most mature, efficient, and eco-compliant method used in modern aluminum recycling plants is “continuous high-temperature carbonization and baking.” The core principle involves controlled-temperature dry distillation (pyrolysis) in an oxygen-free or oxygen-depleted environment.

Baled cans first enter a dual-shaft shredder, where they are cut into uniform flakes measuring 3–5 cm; a magnetic separator then removes impurities such as iron nails and lids. Shredding the cans into flakes significantly improves heat uniformity during the subsequent paint removal process.

The aluminum flakes are fed into a continuous rotary paint-removal furnace. In an oxygen-free atmosphere at temperatures between 500°C and 550°C, the ink and organic resin layers on the cans undergo rapid pyrolysis and dry distillation; the heat causes them to carbonize and naturally flake off. Within this optimal temperature range, the organic paint layers are completely eliminated while the thin aluminum flakes remain intact.

As the flakes tumble inside the rotary drum, they rub against one another, shaking off any residual carbonized ash. Finally, the material passes through a vibrating screen and an air classification system; carbon ash and paint residue are fully extracted, leaving behind clean aluminum flakes that gleam with a metallic luster.