The Recycling of the Tetra-Pak Packages: Research on the Wet Process Separation Conditions of Aluminum and Polythene in the Tetra-Pak Packages

The recycling of tetra-pak packages composed of paper, low-density polyethylene (LDPE), and aluminum is of great recycling significance. The recovering of paper, the major component, was conducted through a Hydrapulper apparatus. The wet separation conditions of the remaining part, a laminated sheet composed of LDPE (0.03 ~ 0.08 mm) and aluminum foil (0.02 ~ 0.03 mm)(Al-PE), was studied in this paper. The separation effect of different separation reagents was compared, and the major process influencing factors, such as the separation reagent concentration, reaction temperature, liquid to solid ratio and solid size was studied. By orthogonal design experiment and variance analysis based on three evaluating indicators, the optimum condition of aluminum and LDPE complete separation using methanoic acid as separation reagent was obtained: 4 mol/L of methanoic acid concentration, 601 of reaction temperature, 60 L/kg of liquid to solid ratio and 5 times 5 cm of solid size, under which the separation rate would reach 100%.