Wastewater from scheelite flotation tailings slathered a lot of sodium silicate in the flotation process, a large number of silicate minerals residues remain in the wastewater, forming suspension bodies difficult to be naturally subsided. With high concentration of suspended substance and pH of 11 or more, this kind of wastewater belongs to unmanageable mine wastewater. Research shows that, pretreating the waste water with Sulfuric acid and calcium chloride, adjusting pH to 7-8 and adding polyacrylamide on flocculating-sedimentation combined can remove suspended solids effectively, offering theoretical basis for wastewater recycling and disposing mine wastewater, which is of great importance.

The passivator of potassium dichromate is one of the main electrolysis manganese passivation technologies in China. The biggest problem of hexavalent chromium passivation is chromium emission. The end-pipe treatment of Cr-containing effluents can be understood as detoxification and precipitation. Here the highly toxicity Cr(Ⅵ) is reduced to low toxicity Cr(Ⅲ) . In alkaline conditions, Cr (Ⅲ)is precipitated in the type of chromium hydroxide and produce chromium residue. The landfill of Chromium residue is a big problem to environment safety. The measures of clean process were reviewed around with emission reduction of Cr.