Method for recovering TDA (Toluene Diamine) from residues and wastes formed in preparation process of TDI (Toluene Diisocyanate)

The invention relates to a method for preparing an important chemical raw material TDA (Toluene Diamine) by carrying out chemical treatment at ordinary pressure on residues and wastes formed in the preparation process of TDI (Toluene Diisocyanate). The method comprises the steps of heating a mixture of crushed TDI residues and ethylene glycol at ordinary pressure till boiling reflux; then adding triethylenetetramine and a NaOH water solution, continuously reacting at 100 DEG C, and finally adding water to a system for cooling to obtain a primary hydrolysis product; carrying out salting-out on the hydrolysis product through a saturated sodium chloride solution, carrying out fractional extraction on the hydrolysis product through dichloromethane, and then carrying out reduced pressure distillation on an extract to prepare the TDA. According to the invention, the yield of the TDA accounts for 60% of the weight of added TDI solid residues, and the purity of the TDA is 95%. The method disclosed by the invention carries out hydrolysis on the TDI residues at ordinary pressure without needing a high-pressure reaction kettle, thereby greatly reducing the cost of production equipment; the method disclosed by the invention is outstanding in economic benefit.