| 摘要 |
<p>A method for removing a cyanide component by or in application of steam stripping while suppressing the formation of a nickel-cyanide complex. A mixture of a raw material and sulfur is fed to a gasification step (101) in a way such that the mixture has a sulfur content of 0.5 to 2.0 wt. % and is gasificated. The resultant crude gas is washed in a cooling/carbon washing step (102), wherein nickel sulfide or the like is preferentially formed in a drain water and the formation of a nickel-cyanide complex is suppressed. A cyanide component is emitted as HCN. Alternatively, to stripper (201), drain water is introduced from line (210), a strong acid from line (211) and steam from line (212). A nickel-cyanide complex contained in a drain water having a controlled pH of 2.0 to 6.0 is decomposed to a cyanide ion and a nickel ion. The cyanide ion is finally emitted as HCN from line (216), and a nickel ion is discharged from line (217) and treated as nickel hydroxide.</p> |
