Steel pickling rust removal waste liquid resource utilization method

The invention relates to a steel pickling rust removal waste liquid resource utilization method which comprises the following steps: filtering a steel pickling rust removal waste liquid twice, detecting the contents of Fe < 3 + > and Fe < 2 + > in the filtrate, adding a reducing agent, carrying out a stirring reaction for 10-30 min, continuously adding oxalic acid, heating to a temperature of 40-100 DEG C, carrying out a stirring reaction for 20-60 min, filtering, washing the obtained precipitate, grinding, standing, aging, and drying, and recovering to obtain ferrous oxalate dehydrate. According to the method, the reducing agent is added into the steel pickling waste liquid to reduce Fe < 3 + > into Fe < 2 + >, and the oxalic acid is added so that substantial separation of Fe < 2 + > andacid in the steel pickling waste liquid is effectively achieved, and the recovery efficiency reaches 80% or above. The ferrous oxalate dihydrate recovered by the method is a high-value chemical raw material, and huge economic