Investigation and Thermodynamic Consideration for Chlorination-Volatilization Behavior of Valuable Metals in Printed Circuit Board Wastes

For the recycling of valuable metals contained in the printed circuit board wastes (PCBW), the effect of temperature on chlorination-volatilization behavior of metals under valuable chlorine resource was investigated. For the experimental sample powder of two types PCBW: crushed PCBW and roasted PCBW was used. The samples were heated at predefined temperatures ranging from 300°C to 900°C with chlorine, argon gas atmosphere or CaCl2 as a solid chlorine source. Chlorine/Argon gas flow into furnace was set at a rate of 100 mL/min. As a result, most of metals in crushed PCBW did not volatilize regardless the temperature, argon gas atmosphere and CaCl2 as chlorine source. In contrast, in the Cl2 gas atmosphere, a lot of metals in crushed and/or roasted PCBW volatilized by raising temperature. Compering the experimental samples, volatilization rate of crushed PCBW is higher than roasted PCBW. This is considered to be influenced by the chemical composition of metals in the samples. When using the crushed PCBW, most metals were volatilized over 90% at 900°C. In addition, in 70% of volatilized metals that were recovered, Cu, Au, Ni were concentrated. According to the results, valuable metals could be recovered by chlorination volatilization from PCBW.