Abstract:Rotary kiln with processing capacity of 100 t/d was designed to recover zinc oxide from wastewater treated sludge of zinc smelting by reduction roasting. The results show that zinc grade of sludge has obvious effect on zinc volatilization result in rotary kiln. With zinc grade in sludge of 5.04% and 8.34% respectively, zinc content of zinc oxide dust in cooling system is 19.4% and 21.4% respectively, and zinc content of zinc oxide dust in baghouse system is 50.2% and 51.6% respectively. Concentrations of heavy metals in lixivium of water-quenched slag are all lower than the limiting value of GB5085.3-2007. Water-quenched slag can be used for production or stockpiled.