Purification method and purification device of 3, 4-dichloronitrobenzene

The invention relates to a purification method and a purification device of 3, 4-dichloronitrobenzene. The purification method provided by the invention comprises the following steps: a nitrification step: reacting o-dichlorobenzene with mixed acid to obtain a nitrification product; a first-stage melting crystallization step: melting the nitrification product, and then cooling and crystallizing to obtain a first-stage crystallization product; and melting and sweating the primary crystallization product again to obtain primary sweat and 3, 4-dichloronitrobenzene crystals. The process does not need to add a solvent, the process is simple, the obtained product is good in yield and high in purity, and compared with a traditional process, the process has obvious safety and environmental protection advantages; moreover, the purification device is simple in structure and high in production efficiency. 本发明涉及一种3,4-二氯硝基苯的提纯方法及提纯装置。本发明提供的提纯方法包括：硝化步骤：使邻二氯苯与混酸反应，得到硝化产物；一级熔融结晶步骤：使硝化产物熔融后降温结晶，得到一级结晶产物；并且，使一级结晶产物再次熔融发汗，得到一级汗