Abstract: Using ammonium bicarbonate and ammonia for leaching zinc ash，and after purification the high-purity zinc-ammonia solution was prepared.Ultrafine basic zinc carbonate was synthesized by hydrolysis-precipitation process with high-purity zinc-ammonia solution as raw material.Finally，ultrafine ZnO could be obtained through calcination of basic zinc carbonate.Influences of heated hydrolysis-precipitation process conditions on the particle size distribution of basic zinc carbonate were investigated.Results showed that under the optimal conditions of mixing speed 300 r/min，reaction temperature 90 ℃，mass concentration of Zn 75 g/L，and underpressure -2 kPa，the basic zinc carbonate was in the shape of sphere-like with an average size （D₅₀） of 0.77 μm.The particle size（D₅₀） of ZnO after calcination was  0.69 μm with hexagonal wurtzite structure.

Key words: hydrolysis-precipitation, basic zinc carbonate, zinc oxide