The preparation method of nanometer ferrous oxalate includes the following steps:

(1) Pretreatment of Ferrous Sulfate as Raw Material

The raw material ferrous sulfate is put into stainless steel water washing kettle, washed and filtered with deionized water, iron powder is recovered, ferrous sulfate is moved into enamel dissolving kettle, ferrous sulfate in enamel dissolving kettle is dissolved with deionized water, then pure iron powder, inhibitor and impurity precipitator are added to adjust the pH value of solution to 1-4, and the solution is stirred thoroughly, then placed in the upper layer for clarification. Ferrous sulfate clarifier was transferred to enamel synthesis kettle for reserve. The amount of iron powder added was 1%-2% of the quality of ferrous sulfate, the amount of inhibitor added was 0.5%-5% of the quality of ferrous sulfate, and the amount of impurity precipitator added was 1%-10% of the quality of ferrous sulfate.

(2) Synthesis of nanometer ferrous oxalate

Adding 100%-300% deionized water of the quality of precipitator to the precipitator, stirring and gradually warming up to 70-90 ~C for reserve; adding the thickener to the clarifying solution of ferrous sulfate, stirring and gradually warming up to 70-90 ~C, the dosage of the thickener is 20%-40% of the quality of ferrous sulfate; adding the precipitator solution to the enamel synthesizer, the molar ratio of precipitator to ferrous sulfate is (0.6-40%). 1):1. Keep the temperature constant and stir for 0.5-2 H. When the precipitation is complete, the supernatant is recovered and the precipitation is nanometer ferrous oxalate.

(3) Washing of nanometer ferrous oxalate

The nano-scale ferrous oxalate was stirred with deionized water for 3-5 minutes, then filtered and separated after standing, and washed repeatedly until no precipitation was detected by barium chloride solution with mass fraction of 20%-30%.

(4) Drying of nanometer ferrous oxalate

The nano-scale ferrous oxalate is obtained by drying the washed nano-scale ferrous oxalate.