| Summary: | 碩士 === 元培醫事科技大學 === 環境工程衛生系碩士班 === 107 === Waste SCR catalysts contain various metals such as As, V, Mo and more. Disposing the waste of SCR catalysts will cause environmental pollution and it is also considered as a waste of resources. The metals of V and Mo are the most essential and valuable metals to help in the separation and recovery of waste catalysts. The metals of V and Mo are the most valuable metals among the others and it is worth to take them out from the metals separation.
In this study, the metal was analyzed based on the metal content in the extract by ICP-OES, and the separation efficiency of each influencing factor was calculated. Firstly, the waste denitrification catalyst was pretreated and extracted with different acid and alkali reagents. It was found that the use of NaOH is more advantageous than the acidic reagent for the dissolution of the metal in the catalyst. When NaOH is used as the extractant, the particle size is 100 mesh. The NaOH concentration is 1.25M, the amount of waste catalyst is 5 (g), L/S is 10, the dissolution time is 1 hr, and the dissolution rates of arsenic, molybdenum and vanadium are 63%, 56% and 47% respectively at normal temperature and 60 °C. The % increased to 80, 81, 72%. After 72 hr dissolution at room temperature, the dissolution rates of As, Mo and V increased to over 95%. Increasing the temperature helped to shorten the dissolution time. When lyophilized at 60 ° C for 1 hr, the efficiency was equivalent. The dissolution rate is 12 hr at room temperature; while phosphoric acid has a better selective dissolution of arsenic than other solvents, the dissolution of arsenic dissolved at room temperature for 72 hr is about 90%, and the dissolution rates of molybdenum and vanadium are less than 50%; Comparing the phosphoric acid at room temperature with 60 ° C, the dissolution time at room temperature for 36 hr is equivalent to the dissolution efficiency at 60 ° C. The arsenic in the catalyst can be removed by calcination, and the arsenic removal efficiency is improved with the calcination temperature. When the calcination temperature is 700 ° C, the arsenic removal efficiency is at least 65% and the vanadium and molybdenum remain almost unchanged, and the continuous calcination temperature is increased. The dissolution of arsenic increases again.
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