Research On The Recovery And Application Of ZnO Dust

Although China is a large country of zinc resources,most of China’s zinc mines are poor ore,the supply of concentrate is insufficient,and at the same time,a large amount of zinc-containing waste has accumulated in long-term industrial production,causing serious environmental pollution.In order to maintain the sustainable and healthy development of zinc resources in China,it is very necessary to comprehensively recycle and utilize various lean minerals,tailings,and zinc-containing industrial solid waste.In Guangxi,a large amount of waste zinc generated by the mining and metallurgical industry has not been effectively recycled,this paper relies on the project of"Research and Industrial Application of Key Technologies for Efficient Reuse of Zinc-containing Secondary Resources",and uses ZnO dust,an intermediate product obtained from the treatment of waste zinc by a rotary kiln in a factory in Guangxi,as raw material for resource reuse process and application research,the main component of which is zinc oxide,which has high resource utilization value.In this paper,after comprehensive analysis of the physical and chemical properties of ZnO dust,a resource utilization scheme suitable for ZnO dust was proposed,and a series of zinc products such as zinc roasted sand,basic zinc carbonate,nano-zinc oxide and Ag-ZnO composite photocatalysts were prepared.The main results obtained are as follows:1.The chemical composition and phase composition analysis of ZnO dust showed that the main component of ZnO dust was ZnO,accounting for 76.14%,and there were 21 other impurity types,including three acid oxides,four amphoteric oxides,and some F,Cl,Br,and the rest were basic oxides.2.The chlorine removal process of ZnO dust was studied by high temperature roasting,and the chlorine removal rate of ZnO dust was used as an index by changing different roasting temperatures and times,and the chlorine removal rate of ZnO dust reached 97.73%and the content of zinc oxide increased to 94.81%under the condition of roasting at 1100°C for 2 h,and the zinc roasted sand obtained could be directly used in wet zinc smelting system.3.The whole process of preparing nano-zinc oxide by ZnO dust was systematically completed,and the results showed that the Leaching rate of Zn could reach 97.48%under the conditions of Na OH concentration of 6 mol/L,solid-liquid ratio of 1:20 and leaching time of 60 min.The p H of the leachate adjusted with sulfuric acid purifies the leachate between 5-5.5,and the separation rates of Pb O,Sn O₂,Al₂O₃,Si O₂ and Cd O reach 94.63%,85.08%,98.03%,91.48%and 88.30%after primary leaching and secondary purification,respectively.Na₂CO₃ was used to prepare basic zinc carbonate of the prebody,and the chemical formula of the precursor was Zn₅（OH）₆（CO₃）₂.Under the condition of decomposition temperature of400°C and decomposition time of 2 h,nano-zinc oxide with particle size of about 20nm was obtained.4.Using the prepared nano-zinc oxide as raw material,the Ag-ZnO composite photocatalyst was successfully prepared by thermal decomposition.Compared to pure ZnO,visible light absorption is stronger,the band gap value is smaller,and the recombination efficiency of photogenerated carriers is lower.The photocatalytic performance was better than that of pure ZnO,among which the 8%Ag-ZnO composite photocatalyst had the best performance,and the photodegradation rate of Rh B（Artificial organic dye rhodamine B）reached 78.79%in 60 min and 89.21%in120 min.The degradation efficiency is 12.61%higher than that of pure zinc oxide.