A method for treating nickel sulfate extraction wastewater

Abstract

The invention discloses a method for treating nickel sulfate extraction wastewater. The method adopts advanced reagent sedimentation + combined ion exchange resin process to deeply remove various heavy metal ions, heavy metal complexes, oils, calcium, magnesium and other pollutants in the extraction wastewater, and can achieve high-standard stable discharge of wastewater, avoiding the disadvantage of secondary pollution caused by chemical reagents introduced by traditional chemical methods for heavy removal; in addition, the wastewater treated by the combined ion exchange process is filtered by a filter paper filter to deeply remove SS, COD and the like in the wastewater, thereby ensuring stable discharge of wastewater treatment in multiple aspects.

Description

Technical Field

[0001] The invention belongs to the field of nonferrous metallurgical wastewater treatment, and specifically relates to a method for treating nickel sulfate extraction wastewater. Background Art

[0002] At present, the most commonly used method for heavy metal wastewater treatment is lime or sulfide neutralization precipitation. It can quickly remove metal ions in wastewater and has a simple process. However, due to the "complex composition, high concentration, multiple types of metal ions, and large amount of water" of heavy metal wastewater, the traditional chemical precipitation method with a single ligand cannot achieve simultaneous deep purification of multiple metals in wastewater. It is difficult for the heavy metal ions in the effluent to stably meet the national emission standards and is prone to secondary pollution.

[0003] The main components of nickel sulfate extraction wastewater are sodium sulfate, nickel, copper, cobalt and other heavy metal ions, calcium and magnesium ions, a small amount of organic matter and other impurities. The wastewater needs to be treated to meet the standards before discharge. Due to the high salt content in the wastewater, the large range of changes in wastewater flow and wastewater pollutant concentration, the key to wastewater treatment is how to achieve stable wastewater discharge standards. It is difficult to completely remove various pollutants in such wastewater at the same time using traditional physical and chemical treatment methods. Summary of the invention

[0004] Based on the above problems, the purpose of the present invention is to provide a method for treating nickel sulfate extraction wastewater, which uses reagent sedimentation + ion exchange resin to deeply treat the wastewater and achieve standard discharge of wastewater treatment. The wastewater purification treatment adopts physical and chemical treatment and advanced combined ion exchange process, which has the advantage of one-time deep removal of nickel, copper, arsenic, lead, calcium, magnesium and other divalent and above metal ions, as well as oils and organic matter under saturated salt concentration.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] S1: The extraction wastewater is pumped into the regulating tank for homogeneous treatment, and then overflows into the pH adjustment tank. After adding dilute sulfuric acid to adjust the pH value to 3-6, it overflows into the flotation tank for oil removal;

[0007] S2: In the flotation tank, the oil in the extracted wastewater is removed by a dissolved air pump, and the oil content of the effluent is controlled to be ≤5ppm. At the same time, activated carbon is added to deeply remove the oil in the wastewater. The amount of activated carbon added is 0.04-0.06 kg / m 3 ;

[0008] S3: The wastewater after oil removal enters the reaction sedimentation tank for multi-stage treatment:

[0009] Primary treatment: adding H 2 O 2 Oxidation reaction with PAC, H 2 O2 The addition amount is 1.0~1.5kg / m 3 The amount of PAC added is 0.03~0.05 kg / m 3 ;

[0010] Secondary treatment: adding liquid alkali to the secondary reaction sedimentation tank to adjust the pH of the system to 7-9 for full hydrolysis;

[0011] In the third stage treatment, sodium carbonate is added to the third stage reaction sedimentation tank for decalcification. The amount of sodium carbonate added is 0.5-1.0 kg / m 3 ;

[0012] In the fourth stage of treatment, PAM is added to the fourth stage reaction sedimentation tank for flocculation. The amount of PAM added is 0.004-0.006 kg / m 3 ;

[0013] S4: The bottom flow after reaction and sedimentation and the scum on the upper layer of the flotation tank are sent to the thickener together. The wastewater after thickening treatment is pumped into the plate and frame filter press for filtration. The filter residue is centrally piled up and safely handled. The water content of the filter residue is ≤25%, and the filtrate is returned to the pH adjustment tank;

[0014] S5: The supernatant after reaction sedimentation is filtered through a bag filter and a sand filter to remove solid particles and organic phase. After two-stage filtration, the solid particles are ≤30ppm and the oil content is ≤5ppm; then it enters the chelating resin for exchange treatment, and the pH is 7-9;

[0015] S6: Add dilute sulfuric acid to the middle water tank and adjust the pH to 6-9;

[0016] S7: The solution after weight removal by the resin enters the filter with a pore size of 1um and is filtered to obtain purified water that meets the discharge standards and then discharged.

[0017] The composition and content of the nickel sulfate extraction wastewater are: Ni ≤0.03 g / L, Cu ≤0.01 g / L, Co ≤0.01 g / L, Pb ≤0.005 g / L, Zn ≤0.01 g / L, As ≤0.001 g / L, Ca ≤0.17 g / L, Mg ≤1.2 g / L, and oil ≤0.01 g / L.

[0018] The principle of wastewater treatment is as follows: the extracted wastewater is collected and enters the regulating tank to homogenize the water quality, and then enters the flotation oil separator through the wastewater lifting pump for oil removal to remove the oil in the wastewater. The oil after flotation is collected after oil separation, and the waste oil is safely disposed of; the wastewater after oil removal enters the primary reaction tank of the weight removal system, and the reaction tank adopts aeration stirring. H 2 O 2, PAC and other agents to produce oxidation reaction to remove COD and petroleum as well as a small amount of heavy metals such as Ni, Cu, Fe, Pb, As, etc. in the wastewater; liquid alkali is added to the secondary reaction tank to adjust the pH value of the system for sufficient hydrolysis, and then a sodium carbonate decalcification position is reserved in the tertiary reaction tank. Finally, PAM is added to the quaternary reaction tank for flocculation and then enters the thickening tank to achieve solid-liquid separation. The supernatant after separation enters the bag filter and sand filter, and the filtrate is further filtered by ion exchange resin to remove Ca, Mg and heavy metal ions. The qualified liquid after de-weighting is adjusted to 6-9 by sulfuric acid and enters the clear water tank, and the effluent meets the discharge standards.

[0019] The present invention has the following beneficial effects:

[0020] The use of advanced reagent sedimentation + combined ion exchange resin technology to deeply remove various heavy metal ions, heavy metal complexes, oils, calcium, magnesium and other pollutants in the extracted wastewater can achieve high-standard stable discharge of wastewater, avoiding the disadvantages of traditional chemical methods of heavy removal that cause secondary pollution by introducing chemical reagents; in addition, the wastewater treated with the combined ion exchange process is then filtered with a filter paper filter to deeply remove SS in the wastewater, ensuring stable and standard discharge of wastewater treatment in multiple aspects. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a process flow chart of the present invention. DETAILED DESCRIPTION

[0022] The present invention is further explained below in conjunction with the accompanying drawings and specific embodiments.

[0023] The emission requirements of the "Special Emission Limits of Water Pollutants" in the "Copper, Nickel and Cobalt Industrial Pollutant Emission Standards" GB25467-2010 are shown in Table 1 below:

[0024] Table 1 Pollutant limits for external drainage (mg / L)

[0025]

[0026] The components of the nickel sulfate extraction wastewater used in Examples 1 to 3 are shown in Table 2 below:

[0027] Table 2 Chemical composition of wastewater (g / L)

[0028]

[0029] Example 1

[0030] like Figure 1As shown in the process flow chart of the present invention, nickel sulfate extraction wastewater is used as the raw liquid for treatment. First, the extraction wastewater flows into the solution homogeneous tank by gravity, and then overflows into the pH adjustment tank. After sulfuric acid is added to adjust the pH value to the target value, it is pumped into the flotation tank; then the oil in the extraction wastewater is removed by the air dissolving pump, and then the mixed solution is pumped into the reaction sedimentation tank; secondly, an appropriate amount of H is added to the reaction sedimentation tank. 2 O 2 , PAC, NaOH (the addition amount of other chemical agents is the same as above) for weight removal, the addition amount is 1.0~1.5, 0.03~0.05, 0.2~0.4kg / m 3 After de-weighting, the wastewater is filtered through bag filters and sand filters in two stages and then enters the ion exchange resin to remove Ca, Mg and other heavy metal ions; finally, the solution after de-weighting by the resin enters the filter paper filter to deeply remove SS, COD, etc. in the wastewater, and finally meets the discharge standards.

[0031] The chemical composition of the effluent after treatment in Example 1 is shown in Table 3 below:

[0032] Table 3 Chemical composition of effluent (mg / L)

[0033]

[0034] It can be seen from Table 3 that the wastewater treated in Example 1 meets the emission requirements of "Special Emission Limits of Water Pollutants" in "Pollutant Emission Standards for Copper, Nickel and Cobalt Industries" GB25467-2010.

[0035] Example 2

[0036] like Figure 1 As shown in the process flow chart of the present invention, nickel sulfate extraction wastewater is used as the raw liquid for treatment. First, the extraction wastewater flows into the solution homogeneous tank by gravity, and then overflows into the pH adjustment tank. After sulfuric acid is added to adjust the pH value to the target value, it is pumped into the flotation tank; then the oil in the extraction wastewater is removed by the air dissolving pump, and then the mixed solution is pumped into the reaction sedimentation tank; secondly, an appropriate amount of H is added to the reaction sedimentation tank. 2 O 2 , PAC, NaOH (the addition amount of other chemical agents is the same as above) for weight removal, the addition amount is ≥1.5, ≥0.05, ≥0.4kg / m 3 After the de-weighting, the wastewater is filtered through a bag filter and a sand filter, and then enters the ion exchange resin to remove Ca, Mg and other heavy metal ions; finally, the solution after the de-weighting by the resin enters the filter paper filter to deeply remove SS and COD in the wastewater. Cr Wait, and finally meet the emission standards.

[0037] The chemical composition of the effluent after treatment in Example 2 is shown in Table 4 below:

[0038] Table 4 Chemical composition of effluent (mg / L)

[0039]

[0040] It can be seen from Table 4 that the wastewater treated in Example 1 meets the emission requirements of "Special Emission Limits for Water Pollutants" in "Pollutant Emission Standards for Copper, Nickel and Cobalt Industries" GB25467-2010.

[0041] Example 3

[0042] like Figure 1 As shown in the process flow chart of the present invention, nickel sulfate extraction wastewater is used as the raw liquid for treatment. First, the extraction wastewater flows into the solution homogeneous tank by gravity, and then overflows into the pH adjustment tank. After sulfuric acid is added to adjust the pH value to the target value, it is pumped into the flotation tank; then the oil in the extraction wastewater is removed by the air dissolving pump, and then the mixed solution is pumped into the reaction sedimentation tank; secondly, an appropriate amount of H is added to the reaction sedimentation tank. 2 O 2 , PAC, NaOH for weight removal (the addition amount of other chemical agents is the same as above), the addition amount is ≤1.0, ≤0.03, ≤0.2kg / m 3 After de-weighting, the wastewater is filtered through a bag filter and a sand filter, and then enters the ion exchange resin to remove Ca, Mg and other heavy metal ions; finally, the solution after de-weighting by the resin enters the filter paper filter to deeply remove SS, COD, etc. in the wastewater, and finally the wastewater is shown in Table 5 below.

[0043] Table 5 Chemical composition of effluent (mg / L)

[0044]

[0045] It can be seen from Table 5 that the wastewater treated in Example 3 does not meet the emission requirements of the "Special Emission Limits for Water Pollutants" in the "Copper, Nickel and Cobalt Industrial Pollutant Emission Standards" GB25467-2010.

[0046] In summary, in order to achieve the standard discharge of wastewater, H 2 O 2 , PAC, and NaOH to ensure that the above H 2 O 2 The added amounts of PAC and NaOH are within the process range.

Claims

1. A method for treating nickel sulfate extraction wastewater, Features: The following steps are involved: S1: The extraction wastewater is pumped into the regulating tank for homogeneous treatment, and then overflows into the pH adjustment tank. After adding dilute sulfuric acid to adjust the pH value to 3-6, it overflows into the flotation tank for oil removal; S2: In the flotation tank, the oil in the extracted wastewater is removed by a dissolved air pump, and the oil content of the effluent is controlled to be ≤5ppm. At the same time, activated carbon is added to deeply remove the oil in the wastewater. The amount of activated carbon added is 0.04-0.06 kg / m 3 ; S3: The wastewater after oil removal enters the reaction sedimentation tank for multi-stage treatment: Primary treatment: adding H 2 O 2 Oxidation reaction with PAC, H 2 O 2 The addition amount is 1.0~1.5kg / m 3 The amount of PAC added is 0.03~0.05 kg / m 3 ; Secondary treatment: adding liquid alkali to the secondary reaction sedimentation tank to adjust the pH of the system to 7-9 for full hydrolysis; In the third stage treatment, sodium carbonate is added to the third stage reaction sedimentation tank for decalcification. The amount of sodium carbonate added is 0.5-1.0 kg / m 3 ; In the fourth stage of treatment, PAM is added to the fourth stage reaction sedimentation tank for flocculation. The amount of PAM added is 0.004-0.006 kg / m 3 ; S4: The bottom flow after reaction and sedimentation and the scum on the upper layer of the flotation tank are sent to the thickener together. The wastewater after thickening treatment is pumped into the plate and frame filter press for filtration. The filter residue is centrally piled up and safely disposed of, and the filtrate is returned to the pH adjustment tank; S5: The supernatant after reaction sedimentation is filtered through a bag filter and a sand filter to remove solid particles and organic phase. After two-stage filtration, the solid particles are ≤30ppm and the oil content is ≤5ppm; then it enters the chelating resin for exchange treatment, and the pH is 7-9; S6: Add dilute sulfuric acid to the middle water tank and adjust the pH to 6-9; S7: The solution after weight removal by the resin enters the filter with a pore size of 1um and is filtered to obtain purified water that meets the discharge standards and then discharged.

2. A method for treating nickel sulfate extraction wastewater according to claim 1, It is characterized in that The composition and content of nickel sulfate extraction wastewater in S1 are: Ni ≤0.03 g / L, Cu ≤0.01 g / L, Co ≤0.01 g / L, Pb ≤0.005 g / L, Zn ≤0.01 g / L, As ≤0.001g / L, Ca ≤0.17 g / L, Mg ≤1.2 g / L, and oil ≤0.01 g / L.

3. A method for treating nickel sulfate extraction wastewater according to claim 1, It is characterized in that After the sludge in S4 is filtered by a filter press, the water content of the filter residue is ≤25%.

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