Waste Brass Ammonia Leaching Recovery Process And Its Preparation And Properties Of Micro / Nano Materials

The recovery of nonferrous resources (RNR) has become one of the main development trends of nonferrous industry, and a hot spot in current research domain.The basic idea of RNR is to implement reduction, consumption of resources, environmental safety and health hazard. Basing on the literature, harmlessness recovery process is a key approach to optimizing and improving the Developing Model of industry. With the development of nanomaterial research, the application of photocatalytic technology for pollution treatment has attracted a lot of attention in all countries.The preparation and application of the photocatalysts with high activity and effective under the sunlight have become hot topics in the areas of materials science, chemistry, environmental science and energy science.The recovering copper using dynamic leaching and cementation techniques was carried out. The effects of leaching time, ammonia, ammonium carbonate and katalyst on the comprehensive leaching ratio were investigated, and the influence of the reducing agent,cementation time and stirring speed on the extraction rate was examined.Furthermore, TiO2 nanotubes(TiO2-NTs) coated with nanosized ZnO particles were successefuly synthesized via a modified deposition-precipition process. Additionally, the photocatalytical mechanism for homodisperse ZnO/TiO2-NTs with high photocatalytic activity was briefly proposed. Meanwhile, ZnO/TiO2-NTs heterojunction could enhance their photocatalytic activities owing to the synergistic effect on photocatalytic properties.Some new and interesting results were achieved and listed as follows.An extensive literature survey on the principles and applications of ammonia leaching precess in hydromentallurgy is presented in this paper. The combination of ammonia and ammonium salts is known to be a powerful lixiviant used in hydromentallurgy process.Many metals can be extracted using the mixture of ammonia/ammonium. Basing on the thermodynamic data, E-pH digrams of various metal-ammonia-water systems are presented. The thermodynamics and kinetics of the dissolution of various metals in ammonia/ammonium salts have been discussed.(1)Ammonium leaching:Optimum leaching conditions:copper 5g; L/S=7:1(ml/g);Ammonia 6 mol/L; Katalyst 12 ml;Leaching time 3 h; Temperature 40℃;Stirring Speed 200rpm.More than 94.89% 94.55% of Cu and Zn was effectively recovered, respectively.(2) Evaporation-acidification System:E-pH diagrams of Zn-Cu-H2O provide useful information regarding the thermodynamically stable phases of metals.(3)Cementation:Optimum conditions:pH=2.5,Temperature 60℃,Time 30 min,Stirring speed 200 rpm and Zn/Cu=0.7 (a.t.),the replacement ratio and purity of Copper are 63.4%,98.5%,respectively. The morphologies of Copper power with sizes of 300nm could be well-controlled through the changes of original concentration of NH3. The formation mechanism of Microspheres Copper nanocrystals was proposed.Nanosized ZnO particles surface-coated TiO2-NTs were prepared via a surface chemical reaction method. It was found that ZnO nanoparticles with sizes of 3-5nm were highly and tightly dispersed on the surface of TiO2-NTs when Zn:Ti=1:4(a.t.)and the concentration of NaOH solution was 0.10 mol·L-1.The effects of Zn coating concentration and calcination temperature on the crystal structure and morphology of the samples were investigated. TiO2-NTs surface coated with a suitable amount of ZnO showed higher efficiency than the undoped TiO2-NTs for photocatalysis. And the atom ratio Zn/Ti=1:4 (a.t.)exhibited excellent photocatalytic activity for photodegradation of methyl orange (MO) compared with P25 and Pure TiO2 NTs,which were mainly caused by increase of interfacial charge transfer reactions and decrease of electron-hole pair recombination on ZnO-TNTs heterojunction.