Recovery method of secondary products of iminodiacetonitrile and mother liquid treatment method

The invention relates to a recovery method of secondary products of iminodiacetonitrile and a mother liquid treatment method. The recovery method comprises the following steps of: (1) introducing ammonia gas to a mother liquid of iminodiacetonitrile to adjust the pH value of a feed liquid to alkalinity; (2) dividing the still feed liquid after stirring reaction in the step (1) into two remarkable layers, namely an organic feed layer and a sulfate aqueous liquor layer, and separating the two phases; (3) cooling, crystallizing and centrifugalizing the organic feed layer to recover the secondary products of iminodiacetonitrile; (4) after performing decoloring treatment on the sulfate aqueous liquor by activated carbon adsorption, feeding the liquor into an evaporation system to obtain a byproduct ammonium sulfate. The method provided by the invention is simple in process and low in investment. Even more importantly, the method provided by the invention can be used for effectively recovering secondary products of iminodiacetonitrile, so that the production yield of a workshop is improved. The sulfate aqueous liquor obtained can be used for recovering the byproduct ammonium sulfate, so that the production cost is lowered.