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This work investigated the thermal treatment to separate and concentrate economically valuable materials from laminates of crystalline silicon photovoltaic modules (i.e., photovoltaic modules without the aluminum frame and the junction box). Chemical characterization of the metal content was performed by X-Ray Fluorescence (XRF). The polymers of the backsheet were also characterized by Fourier Transform Infrared Spectroscopy (FTIR). The influence of the atmosphere (oxidizing and inert) on the decomposition of the backsheet was investigated by Thermogravimetric Analysis (TGA). Moreover, non-comminuted samples were tested for 4 thermal time lengths (30, 60, 90, and 120 min) in the furnace under ambient air. The degradation of the polymers was measured and 3 material fractions were obtained: silicon with silver and residual polymers (SS), glass and copper ribbons. Furthermore, there was no statistical difference between the mass losses of the samples submitted for 90 (13.62 ± 0.02 wt.%) and 120 min at 500 °C (p-value = 0.062). In the SS fraction, silver was 20 times more concentrated than in the ground photovoltaic laminate and 30 times more concentrated than high silver concentration ores. The SS fraction (about 6 wt.%) also presented low copper concentration and a high concentration of lead (hazardous metal). About 79 wt.% glass was obtained, as well as 1% copper ribbons (55.69 ± 6.39% copper, 23.17 ± 7.51% lead, 16.06 ± 2.12% tin). The limitations of the treatment and its environmental impact are discussed, and suggestions for industrial-scale application are given.

The current increase in the use of photovoltaic (PV) energy demands the search for solutions to recycle end-of-life modules. This study evaluated the use of a mechanical pre-treatment in the thermal recycling of c-Si crystalline PV modules, which were submitted to recycling routes to separate and concentrate the materials of interest. The first route was constituted by only thermal treatment, and the second route was constituted by a mechanical pre-treatment to remove the polymers from the backsheet, and subsequent thermal treatment. The exclusively thermal route was performed at 500°C, varying dwell times between 30 and 120 minutes in the furnace. In this route, the best results were obtained in 90 minutes, with a maximum degradation of 68% of the polymeric mass. In route 2, a micro-grinder rotary tool was used to remove the polymers from the backsheet and, subsequently, thermal treatment performed at 500°C, with dwell times in the furnace ranging between 5 and 30 minutes. The mechanical pre-treatment removed about 10.32 ± 0.92% of the mass of the laminate PV module. By this route, only 20 minutes of thermal treatment were needed for the total decomposition of the polymers, that is, a reduction of 78% in the oven time. With route 2, it was possible to obtain a concentrate with 30 times more silver than the PV laminate and 40 times more than a high-concentration ore. Furthermore, with route 2 it was possible to reduce the environmental impact of heat treatment and energy consumption.

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