Method for comprehensive recovery of heavy metal from spent solder stripper

The invention discloses a method for comprehensive recovery of a heavy metal from a spent solder stripper, which mainly comprises steps as follows: a first step: adding pure ammonia to the spent solder stripper and adjusting pH to 9-10 to cause tin and iron to generate precipitation; a second step: obtaining a filter residue and a filtrate by filtration, wherein the main component of the filtrate is a copper ammonia solution; a third step: firstly breaking the filter residue obtained in the second step into small particles, then adding a sodium hydroxide solution to the filter residue under stirring conditions, finally reacting the tin with the sodium hydroxide completely to generate sodium stannate; a fourth step: obtaining the filtrate by filtering; a fifth step: adding sodium sulfide to the filtrate under stirring conditions, then making the solution rest and precipitating the solution; a sixth step: obtaining the filtrate by filtration; a seventh step: dewatering the filtrate obtained in the sixth step to obtain the sodium stannate. The spent solder stripper with high heavy metal content, great danger, complex component and big disposal difficulty is taken as an object. The spent solder stripper can be directly employed after the tin in the spent solder stripper is recovered. The method has good economic benefits and environmental benefits.