Combined treatment method for sodium hypochlorite alkaline wastewater and nickel-containing acidic wastewater

Abstract

The invention belongs to the field of hydrometallurgy, and discloses a combined treatment method for sodium hypochlorite alkaline wastewater and nickel-containing acidic wastewater. According to the method disclosed by the invention, a certain amount of active copper-manganese composite catalyst is added into the sodium hypochlorite alkaline wastewater, so that hypochlorite is catalyzed to react into chlorine and oxygen, and the environmental risk caused by chlorine overflow is reduced. Meanwhile, hydrochloric acid is added for primary neutralization after catalysis, and nickel-containing acid wastewater generated in the production process is subjected to secondary neutralization to adjust the pH value, so that the overall pH value of the wastewater is in accordance with D467 resin heavy removal process parameters. D467 resin is used for removing heavy substances, and Ni which is difficult to treat in the wastewater is adsorbed to the discharge standard.

Description

Technical Field

[0001] The invention belongs to the field of hydrometallurgy and relates to a method for jointly treating sodium hypochlorite alkaline wastewater and nickel-containing acidic wastewater. Background Art

[0002] Sodium hypochlorite is a strong oxidant, widely used as a disinfectant and bleaching agent. Due to the low recycling value of sodium hypochlorite, or the presence of impurities and low concentration, it is chosen to be discharged directly. However, sodium hypochlorite will decompose into chlorine gas when it meets acid. In addition, excessive sodium hypochlorite will produce carcinogen chloroform in aqueous solution. Direct discharge of sodium hypochlorite will pollute the environment. At the same time, the pH of sodium hypochlorite alkaline wastewater is greater than 11. With the implementation of the "Copper, Nickel and Cobalt Industrial Pollutant Emission Standard" (GB 25467-2010), the pH of sodium hypochlorite alkaline wastewater does not meet the discharge standard: pH=6~9 and cannot be discharged directly. In the traditional hydrometallurgical industry, the untreated nickel-containing acidic wastewater contains Ni>0.5mg / L. Due to the low content, it is difficult to carry out deep treatment. With the implementation of the "Copper, Nickel and Cobalt Industrial Pollutant Emission Standard" (GB 25467-2010), the nickel-containing acidic wastewater needs to meet the external discharge standard: Ni <0.5mg / L; Summary of the invention

[0003] The object of the present invention is to overcome the deficiencies of the above-mentioned prior art and to provide a method for jointly treating sodium hypochlorite alkaline wastewater and nickel-containing acidic wastewater.

[0004] To this end, the present invention provides the following technical solutions: A method for jointly treating sodium hypochlorite alkaline wastewater and nickel-containing acidic wastewater comprises the following steps: (1) The sodium hypochlorite alkaline wastewater is filtered once through a filter press; (2) Add the sodium hypochlorite alkaline wastewater after the primary filtration and the active copper-manganese composite catalyst into the reactor, and start stirring at the same time; start steam and heat it to 55-65°C for catalytic reaction, and keep the temperature for 30-60 minutes; The solid-liquid ratio of the active copper-manganese composite catalyst to the sodium hypochlorite alkaline wastewater is 1:300 (g / L); the active copper-manganese composite catalyst was purchased from Zhejiang Zhonghuan Environmental Protection Equipment Technology Co., Ltd., model: XYCLMC-2#; after catalysis, the effective chlorine of the sodium hypochlorite alkaline wastewater is <0.5%.

[0005] (3) After the reaction is completed, industrial hydrochloric acid is added to neutralize the alkaline wastewater after catalysis. When the pH is adjusted to 8-9, stirring is stopped and the wastewater after primary neutralization is pumped into a secondary filter press through a mortar pump for secondary filtration; the industrial hydrochloric acid is 30% industrial hydrochloric acid, and the addition amount is 0.2m³ / m³ of the wastewater after catalysis.

[0006] (4) The alkaline wastewater after the secondary filtration and the nickel-containing acidic wastewater are pumped into the wastewater reaction tank through a return liquid pump for secondary neutralization, and the pH is controlled to be less than 6-9. The filter residue after the secondary filtration is reused as an active copper-manganese composite catalyst; (5) The neutralized wastewater is filtered three times and then pumped into an ion exchange column. It is then deweighted by D467 resin and discharged after reaching the discharge standard. After adsorption by D467 resin, the discharged wastewater contains less than 0.5 mg / L of Ni.

[0007] By adding a certain amount of active copper-manganese composite catalyst into the sodium hypochlorite alkaline wastewater, the hypochlorite ions are catalytically reacted into chloride ions and oxygen, reducing the environmental risk caused by chlorine overflow. Then, hydrochloric acid is added after catalysis for primary neutralization, and the nickel-containing acidic wastewater generated during the production process is neutralized for secondary neutralization to adjust the pH, so that the overall pH of the wastewater meets the D467 resin weight removal process parameters. Through the D467 resin weight removal, the difficult-to-treat Ni in the wastewater is adsorbed to the external discharge standard.

[0008] Compared with the prior art, the present invention has the following beneficial effects: 1. By adding a certain amount of active copper-manganese composite catalyst into sodium hypochlorite alkaline wastewater, the hypochlorite ions are catalyzed to react into chloride ions and oxygen, reducing the environmental risks caused by chlorine overflow.

[0009] 2. After catalysis, hydrochloric acid is added for primary neutralization, and the nickel-containing acidic wastewater generated in the production process is neutralized for secondary neutralization to adjust the pH, so that the overall pH of the wastewater meets the D467 resin weight removal process parameters.

[0010] 3. Through D467 resin weight removal, the difficult-to-treat Ni in the wastewater is adsorbed to the external discharge standard. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a process flow chart of the present invention. DETAILED DESCRIPTION

[0012] The process and effects of the present invention are described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0013] Example 1 1. The pH of the sodium hypochlorite alkaline wastewater used in this embodiment is 12, and the effective chlorine is 13.61%. 20m³ of the sodium hypochlorite alkaline wastewater is pumped into the filter press through a mortar pump for a first filtration, and then returned to the reactor after the first filtration.

[0014] 2. Add 65 kg of active copper-manganese composite catalyst to the reactor and start stirring. The active copper-manganese composite catalyst was purchased from Zhejiang Zhonghuan Environmental Protection Equipment Technology Co., Ltd., model: XYCLMC-2#.

[0015] 3. Turn on the steam and raise the temperature to 60°C. React for 45 minutes. The effective chlorine content of the alkaline wastewater after catalysis is 0.34%.

[0016] 4. After the reaction is completed, close the steam valve, open the hydrochloric acid valve, add 4m³ industrial hydrochloric acid, adjust the pH to 8, stop stirring, close the hydrochloric acid valve, and pump the wastewater after primary neutralization into the secondary filter press through the mortar pump for secondary filtration. Pump the alkaline wastewater and nickel-containing acidic wastewater after secondary filtration into the wastewater reaction tank through the return liquid pump for secondary neutralization to pH = 7; continue to disassemble the filter residue and reuse it in the catalytic process.

[0017] 5. The nickel content of the wastewater after neutralization is 1.61 mg / L. The neutralized wastewater is returned to the ion exchange column and adsorbed with nickel by D467 resin. The flow rate of the liquid is controlled at 7.5 m³ / h.

[0018] 6. According to the analysis results, the pH value of the wastewater after weight removal is 7, and the nickel content is 0.46 mg / L, which meets the direct discharge standard.

[0019] Example 2 1. The pH of the sodium hypochlorite alkaline wastewater used in this embodiment is 11, and the effective chlorine is 9.3%. 22m³ of sodium hypochlorite alkaline wastewater is pumped into the filter press through a mortar pump for a first filtration, and then returned to the reactor after the first filtration.

[0020] 2. Add 70 kg of active copper-manganese composite catalyst to the reactor and start stirring. The active copper-manganese composite catalyst was purchased from Zhejiang Zhonghuan Environmental Protection Equipment Technology Co., Ltd., model: XYCLMC-2#.

[0021] 3. Turn on the steam and raise the temperature to 60°C. React for 30 minutes. The effective chlorine content of the alkaline wastewater after catalysis is 0.0.052%.

[0022] 4. After the reaction is completed, open the hydrochloric acid valve and add 3.5m³ industrial hydrochloric acid, adjust the pH to 9, stop stirring, close the hydrochloric acid valve, and pump the wastewater after primary neutralization into the secondary filter press through the mortar pump for secondary filtration. The alkaline wastewater and nickel-containing acidic wastewater after the secondary filtration are pumped into the wastewater reaction tank through the return liquid pump for secondary neutralization to pH = 8; the filter residue is further disassembled and reused in the catalytic process.

[0023] 5. The nickel content of the wastewater after neutralization is 1.21 mg / L. The neutralized wastewater is returned to the ion exchange column and the nickel is adsorbed by D467 resin. The liquid flow rate is controlled at 7.5 m³ / h.

[0024] 6. According to the analysis results, the pH of the wastewater after weight removal is 8, and the nickel content is 0.3 mg / L, which meets the direct discharge standard.

[0025] The above are preferred embodiments of the present invention. Any simple modification, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A method for jointly treating sodium hypochlorite alkaline wastewater and nickel-containing acidic wastewater, characterized in that: The following steps are involved: (1) The sodium hypochlorite alkaline wastewater is filtered once through a filter press; (2) Add the sodium hypochlorite alkaline wastewater after the primary filtration and the active copper-manganese composite catalyst into the reactor, and start stirring at the same time; start steam heating to 55-65°C, and keep the temperature for 30-60 minutes; (3) After the reaction is completed, industrial hydrochloric acid is added to neutralize the alkaline wastewater after catalysis, and the pH is adjusted to 8-9. Stirring is stopped, and the wastewater after primary neutralization is pumped into the secondary filter press through a mortar pump for secondary filtration; (4) The alkaline wastewater after the secondary filtration and the nickel-containing acidic wastewater are pumped into the wastewater reaction tank through a return liquid pump for secondary neutralization, and the pH is controlled to be less than 6-9. The filter residue after the secondary filtration is reused as an active copper-manganese composite catalyst; (5) The neutralized wastewater is filtered three times and then pumped into an ion exchange column. It is then deweighted by D467 resin and discharged after reaching the discharge standard.

2. The combined treatment method of sodium hypochlorite alkaline wastewater and nickel-containing acidic wastewater according to claim 1, characterized in that: The pH value of sodium hypochlorite wastewater is 11-12, and the effective chlorine is 1%-15%; the pH value of nickel-containing acidic wastewater is 7-8, and the nickel content is Ni<2mg / L.

3. The combined treatment method of sodium hypochlorite alkaline wastewater and nickel-containing acidic wastewater according to claim 1, characterized in that: The solid-liquid ratio of active copper-manganese composite catalyst to sodium hypochlorite alkaline wastewater is 1:

300.

4. The combined treatment method of sodium hypochlorite alkaline wastewater and nickel-containing acidic wastewater according to claim 1, characterized in that: The available chlorine in sodium hypochlorite alkaline wastewater after catalysis is less than 0.5%.

5. The combined treatment method of sodium hypochlorite alkaline wastewater and nickel-containing acidic wastewater according to claim 1, characterized in that: Industrial hydrochloric acid is 30% industrial hydrochloric acid, and the addition amount is 0.2m³ / m³ of catalytic wastewater.

6. The combined treatment method of sodium hypochlorite alkaline wastewater and nickel-containing acidic wastewater according to claim 1, characterized in that: After adsorption by D467 resin, the discharged wastewater contains Ni < 0.5 mg / L.

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