The Synthesis and Reuse of Zinc-Ferrite from the Electric Arc Furnace Dust of Steel Industry

• Main Authors: LIN, YI-JHEN, 林怡珍
• Other Authors: CHEN, JHIH-CHENG
• Format: Others
• Language: zh-TW
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/5e6h7y

碩士 === 逢甲大學 === 環境工程與科學學系 === 106 === The steel industry is the foundation of industrial development and is therefore often regarded as an indicator of national power. According to the statistics of Taiwan Environmental Protection Administration, the declared amounts of steel dust ash in Taiwan is about 250,000 metric tons in recent years. The steel dust/ash contains a lot of heavy metal compounds, so it is more difficult to disposal. At present, most of steel dust/ash are treated by thermal methods to recover the zinc oxides and the cost of the treatment is considerable. In order to effectively improve the reuse benefits of steel dust/ash and increase the values of reuse products, this study mainly investigates the characteristics, treatment and reuse technology of steel electric arc furnace dust. The chemical metallurgy method was used to recover the metals of steel electric arc furnace dust, and then the coprecipitation method was used to synthesize the zinc-ferrite. The influences of different synthesis factors were investigated and the optimum operating conditions were determined. The synthetic zinc-ferrite was further used as a catalyst for air pollution control, and the catalytic activity and optimal reaction conditions for different pollutants were explored. The zinc-ferrite was synthesized from the steel electric arc furnace dust with the optimum metal recovery conditions. The catalytic activity of the synthetic zinc-ferrite catalyst was tested. The results showed that the best recovery efficiency of zinc and iron was obtained as the reagent was hydrochloric acid, the reagent concentration was 12 M, the microwave reaction temperature was 120 °C, and the reaction holding time was 25 minutes. Among these operation factors, the reagent type had the most important influence and followed by the microwave reaction temperature, the reagent concentration and the reaction holding time. The optimum synthesis condition of zinc-ferrite was occurred as the Zn/Fe molar ratio was 1/2.5, the pH of coprecipitation solution was 10, the aeration time was 3 hours and the calcination was operated at 500 °C for 2 hours. Among these synthesis factors, the Zn/Fe molar ratio had the most important influence and followed by the pH of coprecipitation solution, the calcination temperature and the aeration time. The results of catalytic activity tests show that most of the zinc-ferrites synthesized at different conditions had good performance. When the space velocity was controlled at 10,000 hr-1 and the reaction temperature was 300°C, the conversion rate of propylene could reach 98% and the conversion rate of nitric oxide could reach 85-92% when the reaction temperature was 400°C. As a result, reuse of steel electric arc furnace dust for the synthesis of zinc-ferrite was feasible and the application of zinc-ferrite as a catalyst for the removals of propylene and nitric oxide was effective. Moreover, the leachability of different heavy metals from the synthesized zinc-ferrite were very low and far below the limits of Toxicity Characteristic Leaching Procedure. Through this recycling method, the goal of harmless and reusable of steel dust can be achieved.