Recovery method of copper-nickel heavy metals in electroplated mixed-flow waste water

Abstract

The invention relates to a recovery method of copper-nickel heavy metals in electroplated mixed-flow waste water. The recovery method comprises the following steps of: using lime to adjusting the pH value to be 2.5-3 in the electroplated mixed-flow waste water containing copper and nickel, adding a flocculating agent PAM (polyacrylamide), generating precipitate, and carrying out solid-liquid separation; then adding sodium sulfide, generating copper sulfide precipitate, and carrying out solid-liquid separation; then adding hydrogen peroxide for preventing complexation, using the lime to adjusting the pH value to be 6.5, simultaneously precipitating copper and chromium ions, adding the flocculating agent PAM, and carrying out solid-liquid separation; then using the lime to adjusting the pH value to be 10.5, simultaneously adding sodium hypochlorite for preventing complexation, generating precipitate containing nickel hydroxide, adding the flocculating agent PAM, carrying out solid-liquid separation, and recovering nickel mud; and finally, adjusting the pH value of the discharged water to be 8 by adding sulfuric acid, and realizing standard discharging. The recovery method has the advantages that the process is simple and convenient, the operation is easy, the recovery cost is low and the recovery rate is higher.

Description

technical field [0001] The invention relates to a method for recovering heavy metals in wastewater treatment, in particular to a method for recovering copper-nickel heavy metals in electroplating mixed-flow wastewater. technical background [0002] In the prior art, the heavy metal treatment and recovery technologies in electroplating wastewater mainly include: chemical precipitation method, ion exchange method, electrolysis method, membrane separation method, electrodeionization method and other new methods. The ion exchange method is a method of removing metal ions in water by means of an exchange reaction between ions on the ion exchanger and ions in the water. It has played a huge advantage in the recovery of heavy metals in rinsing water and pouring bath liquid; the electrolysis method is mainly It is carried out in the electrolytic cell, and the positive and negative electrodes of the external power supply are respectively connected to the anode and cathode of the elec...

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Problems solved by technology

[0003] At present, the above methods have been applied to a certain extent, but these methods are all aimed at a certain type of wastewater, and the application conditions are strict. It is required to strictly divert the electroplating wastewater first, and the water volume should not be too large; and in the actual production process , in electroplating concentrated areas and large-scale electroplating enterprises, it is difficult to achieve a complete diversion of wastewater, and the phenomenon of mixed flow of wastewater is very serious. Under such conditions, the above method is difficult to apply

[0004] Chemical precipitation method is a commonly used method for treating electroplating wastewater. It mainly adopts the method of adding alkali (commonly used lime) to precipitate metals, and at the same time adding some oxidizing agents (complexation breaking), reducing agents (reducing chromium) and precipitation aids (PAM ) and other reactions, the effluent can basically meet the standard, but in this process, the output of mixed sludge is large, the sludge grade is low, and it is difficult to reuse

The sludge is of low grade (both copper and nickel content are very low), can not be reused at all, and can only be disposed of as hazardous solid waste. The disposal cost reaches 300 yuan / ton, which seriously affects the profitability of the enterprise and wastes a lot of metal resource

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