Mass balance and quantitative analysis of cleaner production potential in a zinc electrolysis cellhouse

Mass balance studies of wastewater from the zinc electrolysis cellhouse of an operating zinc production facility were conducted. A wastewater volume of 336.8 L was generated per tonne of electrolytic zinc produced, containing 20,230 mg Pb2+, 591.7 mg Cd2+ and 3.712 kg Zn2+. The mass balance showed that dissolution of zinc from the cathode plates during washing in the plate bathing tank contributed 82.2% of the Zn2+ found in the cellhouse wastewater. A thermodynamic analysis of possible reactions was used to confirm that zinc dissolution was the main mechanism by which Zn2+ ions entered wastewater. The volume of wastewater generated in the cellhouse is a function of the rate at which the electrolyte carried out by cathode plates is reduced, and the rate at which crystallized zinc sulfates are reduced. Calculations based on theory intuitively proved and quantified the potential of cleaner production in reducing wastewater generated in a zinc electrolysis cellhouse.