Patent ID: 9527801
Filing Date: 2016-12-27
CPC Classification: C01B,C07C

Claim Text:
1. A process for recycling waste acid produced in the process of producing Zoalene, comprising a nitration process, a chlorination process and an ammonization process, wherein the nitration process comprises the following steps: putting concentrated sulfuric acid into an enamel reactor ( 12 ), starting a mixer ( 18 ), putting in ortho-toluic acid and mixing it until completely dissolved, adding nitric acid to the system, controlling the system temperature at 90-100 DEG. C., continuously mixing to react for 0.5-1.5 h after added, and then cooling; diluting the liquid with distilled water, then filtering, and then washing and drying the solid to obtain a nitration product 3,5-dinitro-2-methylbenzoic acid; putting the waste acid which is diluted and washed in the nitration process into a distillation tower ( 1 ), later heating, depressurizing and distilling; setting the vacuum degree for depressurizing and distilling the water acid at 0.07-0.1 MPa, putting the acid liquid A obtained by distillation and concentration into a mixing tank ( 8 ), and adding new concentrated sulfuric acid to the mixing tank ( 8 ), wherein the mass ratio of the acid liquid A to the new concentrated sulfuric acid mixed above is 1-5:1; after mixing, putting the mixed sulfuric acid to a reactor to carry out a new nitration reaction; recycling and putting the distilled water A which is obtained by heating, depressurizing and distilling into a condenser ( 15 ) for cooling, storing the cooled distilled water A in a recycled water storage tank ( 17 ), and putting the distilled water A to a diluting pot ( 13 ) to dilute the 3,5-dinitro-2-methylbenzoic acid produced in the new nitration process.