Chlorination Roasting of Oxidized Component Obtained from Dross at a Temperature of 1000°C

Work is devoted to solution of the problem of processing dross obtained as a result of hot galvanizing of products, in particular, waste-free utilization of its oxidized component by chlorination firing using cheap chlorine-containing CaCl₂ and NH₄Cl reagents. Results of chlorination roasting of the dross oxidized component together with CaCl₂ and NH₄Cl at a 1000°C are presented. The effect of CaCl₂ and NH₄Cl consumption on lead and iron sublimation from the dross oxidized component in the form of chlorides is studied. It is found that use of CaCl₂ with a consumption equal to 6% of the weight of the oxidized component provides thorough purification of the starting material from Pb, Cu, Ni, Cd. Maximum reduction of the iron content is not possible. It is shown that use of NH₄Cl with a consumption of 15% of the weight of the oxidized component provides thorough removal of impurity metals and metallic zinc from the source material. It is found that with a firing temperature of 1000°C thorough sublimation of impurities is achieved, which ensures production of pure zinc oxide, suitable for use as a mineral additive in animal and bird feed. The content of metal impurities in the resulting zinc oxide is, wt.%: Pb 0.02, Fe 0.08, Ni 0.02, Cu 0.008, Cd 0.001. Optimum firing parameters are established: T = 1000°C, duration 60 min, air flow 0.1 liter/min, CaCl₂ consumption 6%, and NH₄Cl 15% of the weight of the oxidized component.