Composite chemical leaching method for remediation of heavy metal contaminated soil

The invention discloses a composite chemical leaching method for remediation of heavy metal contaminated soil. The method includes: leaching heavy metal contaminated soil 1-3 times by a composite leacheate prepared from ferric chloride and an organic acid, then further conducting leaching 1-3 time with distilled water, and finally separating the leacheate from soil. The method provided in the invention has the advantages of good treatment effect, short leaching time, no secondary pollution, simple operation, relative low cost, a highest cadmium removal rate of over 80%, and a highest lead removal rate of over 55%. The iron-containing compound involved in the invention is used as an improver of paddy soil. The residue of ferric chloride has a positive effect on chemical properties of soil, and cannot destroy the soil structure. The used organic acid is easy to degrade, and the degradation product can become nutrients of plants and is environment-friendly. The final leaching by water can reduce the content of metal ions and the leacheate residue in the remedied soil, thus being in favor of later crop tilling.