A method for removing Cr(VI) from wastewater by preparing manganese-iron oxalate composite oxide using iron-rich manganese slag

Abstract

The present invention discloses a method for removing Cr(VI) from wastewater by preparing oxalate manganese-iron composite oxide using iron-rich manganese slag. The steps are as follows: first, the iron-rich manganese slag just discharged from the filter press workshop is transported to a slurry mixing tank, and then water and sulfuric acid in a set ratio are added to the slurry mixing tank. After the mixture is evenly mixed, solid-liquid separation is performed to obtain a leachate and a leach residue; second, iron powder and oxalic acid in a set ratio are added to the leachate, and after sufficient reaction, solid-liquid separation is performed to obtain a solid precipitate, which is the oxalate manganese-iron composite oxide; finally, the oxalate manganese-iron composite oxide in a set ratio is added to a certain concentration of chromium-containing wastewater, and Cr(VI) is removed from the chromium-containing wastewater under set reaction temperature, current density, reaction pH and other conditions, so that the wastewater can meet the discharge standards. The overall process of the present invention has the advantages of simple operation and low cost. It can not only effectively improve the recycling of iron and manganese resources in the iron-rich manganese slag, but also achieve efficient removal of Cr(VI) from wastewater.