Study On The Technology Of Comprehensive Recovery And Utilization Of Secondary Zinc Oxide

Secondary zinc oxide is an important secondary resource which contains large amounts of zinc,lead,cadmium and other valued metals,therefore it has high comprehensive recovery value.Secondary zinc oxide was usually used as inorganic fillers or to synthesize low grade zinc products and the case that secondary zinc oxide was used to prepare products wih high value added is rare.In this thesis,basic zinc carbonate and sheet nano basic zinc carbonate were prepared by different process routes,using zinc ammonium complex from secondary zinc oxide as raw material,and sheet nano zinc oxide was prepared using sheet nano-basic zinc carbonate as precursor.The products structure and morphology were fully characterized by XRD,FESEM and the quality of the products were tested by chemical analysis.The recovery and utilization of other valued metals were preliminarily discussed.Production equipments of the preparation of sheet nano zinc oxide were suggested through the studies,as well as economic benefits and environment analysis.The main results obtained are as follows:(1)The optimum conditions of ammonia leaching process of secondary zinc oxide and the extraction process of zinc ammonium complex were obtained.Chemical analysis results showed that the zinc extraction of secondary zinc oxide reached 90.26%,impurity removing efficiency of zinc-ammonium complex reached 99.92%.(2)The conditions of the recovery and utilization of valued metals from residue of the extraction process were obtained.Chemical analysis results showed that the recovery of cadmium reached 92.8%,the purity of cadmium sulfate reached 98.1%,the recovery of copper reached 94.2%,the purity of sponge copper reached 97.9%,the recovery of lead reached 61.9%,the purity of lead sulfate reached 98.8%.(3)The optimum conditions of the preparation of sheet nano basic zinc carbonate by air stripping method through zinc ammonium complex from secondary zinc oxide were obtained.It can be seen in FESEM image that the basic zinc carbonate was sheet-like structure with narrow distribution and the average thickness was 10 nm.Chemical analysis results showed that the recovery of zinc reached 99.8%,the zinc content of basic zinc carbonate reached 58.1%and the granularity in 75(μm)(200 mesh)was 100%.The sheet nano basic zinc carbonate accorded with grade A basic zinc carbonate.(4)The optimum conditions of the preparation of basic zinc carbonate by carbon dioxide neutralization through zinc ammonium complex from secondary zinc oxide were obtained.Chemical analysis results showed that the recovery of zinc reached 99.51%,the zinc content of basic zinc carbonate reached 57.62%and the granularity in 75(μm)(200 mesh)was 100%.The basic zinc carbonate accorded with grade A basic zinc carbonate.(5)The optimum conditions of the process of sheet nano zinc oxide was prepared using sheet nano basic zinc carbonate as precursor were obtained.It can be seen in XRD and FESEM that the ZnO was hexagonal crystal wurtzite phase,crystallinity was good,average thickness was 10 nm.Chemical analysis results showed that the purity of sheet nano zinc oxide reached 99.25%.The sheet nano-zinc oxide accorded with lclass nano zinc oxide.(6)The results of economic benefit estimation showed that,the production of sheet nano-zinc oxide from secondary zinc oxide had good economic benefits.The environmental analysis showed that in this manufacturing process there was nearly no waste pollution.So it was a clean production process.