Study On Preparation Of Nanometer Zinc Oxide From Zinc-Containing Dust Of Rotary Hearth Furnace Treated By Eutectic Solvent

The iron and steel industry plays an indispensable role in the development of my country's economic construction,but with the rapid development of the iron and steel industry,many problems that follow have also been exposed.The iron and steel industry consumes a lot of resources and energy.At the same time,a large amount of solid waste will inevitably be generated in the production process.In 2020,my country's crude steel output will be about 1 billion tons,and the resulting solid waste will be about 100 million tons.It causes serious environmental pollution and waste of resources,which is not in line with my country's sustainable development strategy.At present,a variety of solid waste treatment methods have been developed and applied in China.Among them,the rotary hearth furnace method has significant results in the recovery and treatment of zinc-containing dust in steel plants.However,the recovered zinc-containing dust is generally sold directly,which is useful for improving zinc-containing dust.There is not much attention to the value-added issue.As a new type of green solvent,eutectic solvent has the advantages of selective solubility,low toxicity,biodegradability,and alternative surfactants.It is used as a solvent for treating zinc-containing dust in rotary hearth furnaces and is prepared at the same time as purification Nano zinc oxide can effectively increase the added value of zinc dust in rotary hearth furnaces.In this thesis,eutectic solvent is used as the research system,and zinc-containing dust in rotary hearth furnace is the research object.The selective solubility of eutectic solvent and the characteristics of alternative surfactants are used to purify zinc-containing dust and prepare nano-zinc oxide.First,the thermal stability of choline chloride-urea-zinc oxide(Ch Cl-urea-Zn O)and choline chloride-oxalic acid dihydrate-zinc oxide CC-OA-Zn O systems were systematically studied;the rotary hearth furnace was carried out Research on the purification process of zinc-containing dust,using single factor and response surface design to design leaching experiments to investigate the influence of various factors on the yield of zinc oxide.The thermal decomposition of the precursors prepared by the Ch Cl-urea and CC-OA systems was studied and the thermal decomposition kinetics was calculated.The main research contents and conclusions are as follows:(1)With the increase of?(Zn O)in the Ch Cl-urea-Zn O system,the TG and DTG curves of the solution move towards the high temperature direction,showing better short-term thermal stability.When 0 h<t<8 h,the higher the?(Zn O),the better the long-term thermal stability,when 8 h<t<16 h,the higher the?(Zn O),the longer the thermal stability gradually deteriorates;and when 16 h<t<64 h When?(Zn O)is higher,the long-term thermal stability is worse;as?(Zn O)increases,the color of the final solution gradually changes from colorless to yellow and then to black,and swelling occurs.In the CC-OA-Zn O system,with the increase of?(Zn O),the TG and DTG curves of the solution move towards high temperature,showing better short-term thermal stability.When 0 h<t<64 h,the higher the?(Zn O),the better the long-term thermal stability,and the final phenomenon does not change much from the original.(2)In Ch Cl-urea and CC-OA leaching experiments,it is found through single factor experiment that the leaching temperature and leaching time have a greater impact on the yield of zinc oxide,and the effect on the yield of zinc oxide is obtained through response surface design.Temperature>leaching time>liquid-solid ratio.In the Ch Cl-urea zinc particle replacement delead experiment,the delead rate basically reached 100%under the best delead condition.XPS,which is extremely sensitive to elements,did not detect lead,and at the same time clarified the delead mechanism.(3)The precursors obtained by Ch Cl-urea and CC-OA are Zn₄CO₃(OH)₆·H₂O and Zn C₂O₄·2H₂O,both of which are the research target of thermal analysis kinetics in the second stage of thermal decomposition of the precursor,and the average activation energy of the reaction is obtained.They are 244.01 and 220.09 k J/mol.According to the phenomenological equation,the average activation energy for grain growth of nano-zinc oxide is calculated to be 47.3 and 6.13 k J/mol,and the optimal calcination conditions are determined.Compare Ch Cl-urea(A),CC-OA(B),CC-OA post-Ch Cl-urea(BA)and Ch Cl-urea first and then CC-OA(AB)four treatment processes on the precursor and nano-oxidation The effect of zinc properties.The precursor of the A process is Zn₄CO₃(OH)₆·H₂O,and the precursors of the B,BA,and AB processes are all Zn C₂O₄·2H₂O;the A,B,BA and AB processes obtain Zn O content of 98.332%,99.768%,99.733,and 99.76%.Processes A,B and B-A can all obtain nano-zinc oxide aggregated together in a spherical shape,and the particle size distribution is normal.Among them,the B process has the best effect to obtain nano-zinc oxide,with an average particle size of 28.5nm.However,the nano-zinc oxide obtained by the A-B process has a poor effect,a wide range of particle size distribution,and an average particle size of 259 nm.