Technology Research On Preparation Of Nanometer ZnO By Hot Galvanizing Dross

Nano zinc oxide is a kind of multi-functional inorganic material, because of the subtle grain, its surface electronic structure and crystal structure have changed, and it possess some characteristics ,such as surface effect, volume effect, quantum size effect and macro tunnel effect and high transparency, high dispersion. In recent years , it has shown many special function in catalysis, optical, magnetism, mechanics, which are unabled to compare with common zinc oxide .At present all kinds of preparation methods of nanometer zinc oxide are used in high purity of zinc salt or metal zinc as raw materials, which not only limits the raw material source of nanometer zinc oxide, but also increased the production cost, influenced the popularization and application of nanometer zinc oxide.Nanometer zinc oxide was prepared through oxygen control by vacuum using waste galvanized zinc as raw materials. Through theoretical calculation and analysis shows that the oxidation of zinc vapor is a spontaneous reaction thermodynamics and reaction tendency greats in the experimental conditions; By adjusting the vacuum system, we can control the size of the molecular mean free path, When theλlarger , the less the number of the collision, the smaller the powder particle size, so nano-ZnO can be obtained under the conditions of vacuum; In this experiment, the movement of air in the form of viscous flow is turbulent gas, its flow line is very rules,what is conducive to the growth of ZnO crystal orientation; In the preparation of nano-ZnO, the metal zinc, iron, aluminum, nickel can be well separated , the impurity elements such as iron, aluminum, nickel basically left in the slag, while zinc was mainly enriched in the gas phase, which contains only trace iron, aluminum, nickel that can be neglected.The influence of the reaction conditions on the morphologies of the product was investigated with SEM and XRD detection means; and the behavior of the main impurity element under different oxidation condition and its influence on the quality of the product were determined; and galvanized slag oxidation dynamics was researched.Experimental results show that, different reaction temperature or vacuum system has a great influence on the morphology of the product.The product is mostly hexagonal wurtzite structure of Tetrapod zinc oxide, the root diameter of which is about 50nm, the needle length is 0.3μm 4.0μm, slender needles, large aspect ratio, size and morphology of nano-ZnO are relatively uniform when the temperature at 850℃, reaction time at 8min and the system pressure at 21975Pa, and the recovery rate of Zn is more than 90% .The different behaviors of impurity Fe and Pb affect the quality of product in different way under different oxidation condition. The joining of Fe into the product was mainly due to mechanical entrainment of zinc and the Fe-Zn systems positive bias effect, however, the Pb joins in the product because of its evaporation pressure and Pb-Zn systems positive bias effect. Therefore, controlling the appropriate reaction temperature and vacuum degree can reduce the impurities in the products.The kinetics study shows that when the vacuum is greater than or equal to 21975Pa, the zinc oxidation followed the parabolic law, and when the vacuum is 19975Pa, the zinc oxidation comply linear law. And further researched that the prestudies process of oxidation reaction was controlled by R3 mode (contraction spherecial model), and dominated by the D4 mode (3D diffusion model) later, and the apparent activation energies were 101.3 122.1 J·mol ^{- 1} ·K·1and 111.2 143.4 J·mol ^{- 1} ·K·1; The model of D4, the diffusion coefficient of zinc atoms pass through the oxide film is 0.92 4.85×10^-5cm² / s.