Study On Cyanide Removal From Washing Wastewater Of Blast Furnace Gas

Alkaline-Chlorination Process and Fe²+—PAM process were investigated by removing cyanide from washing wastewater of blast furnace gas by means of orthogonal experiment design; and there were discussed the reaction conditions, factors . At last, characteristics of two processes were compared.I The optimal reaction conditions, the ranking of the factors, and the markedness of the factors of the alkaline-chlorination process were found out from the data of the experiments on the base of intuitionistic and variance analysis.[1] Cyanide in washing wastewater of blast furnace gas could be more effectively removedby the alkaline-chlorination process [2] The sequence of factors:T >a₁> pH₂> pH₁>a₂>t₂>t₁;[3] Temperature was mostly marked and a₁ was marked in these factors; [4] The optimal reaction conditions:T=35℃, pH₁=11,t₁=25min,a₁=3,pH₂=7.5,t₂=35min,a₂=2.5.II According to the investigations of the Fe²+—PAM process conclusions were obtained as follows:[1] Cyanide in washing wastewater of blast furnace gas could be more effectively removedby the Fe²+—PAM process; [2] The sequence of factors in the first step:T₁ >a₁> pH₁>tr₁>td₁; [3] The optimal reaction conditions in the first step:T₁=30℃,pH₁=6,a₁=3.5,tr₁=40min, td₁=35min; [4] The sequence of factors in the second step:T₂ >tr 2>M> pH₂>td 2; [5] The optimal reaction conditions in the second step:T2=30℃, pH₂=6.5, M=30mg,tr₂=45min, td₂=45min.Cyanide in washing wastewater of blast furnace gas could be more effectively removed bythe alkaline-chlorination process. However, in operating process CNCl could so easily volatilize that it was dangerous to workers. Because pH was fluctuated widely, the equipments should be adopted corrosion inhibition. The reagents were expensive. In a word, the running cost was very high., Its operation was simple, pH is from 6 to 7, the equipments didn't need specially treating, and most of equipments in the systems could be utilized, although the results of Fe2+—PAM process was worse than that of AJkaline-Chlorination Process, Conclusively, the Fe2+—PAM process was obviously advantageous in the running cost.