Method for separating and purifying low-concentration copper and nickel

Abstract

The invention discloses a low-concentration copper and nickel separation and purification method which comprises the following steps: low-concentration copper and nickel-containing wastewater passes through a coarse screen, coarse impurities in the wastewater are removed by the coarse screen to obtain first wastewater, and the first wastewater is discharged to a first pH adjusting tank; the pH value of the first wastewater is adjusted to be weakly acidic by the first pH adjusting tank, and suspended solids in interference factors are filtered out by using a ceramic ultrafiltration membrane to obtain second wastewater; the resin adsorption module is used for enriching copper and nickel ions in the second wastewater, strong acid is used for eluting adsorption resin to obtain a first salt solution containing high-concentration copper and nickel ions, and the first salt solution is subjected to extraction operation of a copper-containing salt product and a nickel-containing salt product. According to distribution coefficients of copper and nickel in different phases, a water-phase detergent containing certain copper and nickel ions is prepared, and the purpose of separating and purifying copper and nickel is achieved through repeated washing.

Description

Technical Field

[0001] The invention relates to the technical field of heavy metal separation, and in particular to a method for separating and purifying low-concentration copper and nickel. Background Art

[0002] For various industrial wastewaters, domestic sewage and nuclear industrial wastewater containing heavy metal ions, chemical precipitation, oxidation-reduction or ion exchange methods are generally used to treat them, thereby reducing the heavy metal content in water resources and reducing the hazards of heavy metal pollution.

[0003] However, the various heavy metal wastewater treatment methods currently used have the disadvantages of low removal efficiency and high cost of heavy metal ions in the wastewater. Summary of the invention

[0004] The main technical problem solved by the present invention is to provide a method for separating and purifying low-concentration copper and nickel. According to the distribution coefficients of copper and nickel in different phases, an aqueous phase detergent containing certain copper and nickel ions is configured, and the purpose of separating and purifying copper and nickel is achieved through multiple washing.

[0005] In order to solve the above technical problems, a technical solution adopted by the present invention is: to provide a method for separating and purifying low-concentration copper and nickel, comprising the following steps: A method for separating and purifying low-concentration copper and nickel, characterized in that it comprises the following steps: S1, passing low-concentration copper and nickel-containing wastewater through a coarse screen, the coarse screen removes coarse impurities in the wastewater to obtain first wastewater, and the first wastewater is discharged into a first pH adjustment tank; S2, the first pH adjustment tank adjusts the pH value of the first wastewater to a weak acid to exclude interference factors that can form precipitation for initial precipitation, and uses a ceramic ultrafiltration membrane to filter and remove suspended matter in the interference factors, and controls the concentration of the suspended matter to below 10 mg / L to obtain the second wastewater; S3, the resin adsorption module enriches the copper and nickel ions in the second wastewater, and the enrichment concentration reaches at least 50000 mg / L, and the adsorption resin is eluted with a strong acid to obtain a first salt solution containing high concentrations of copper and nickel ions; S4, the first extraction module uses a copper ion extractant to extract the first salt solution, and the ratio of the water phase to the oil phase during extraction is 2:1, to obtain a first oil phase and a first water phase containing more copper and less nickel, and the first oil phase enters the first washing module; S5, the first washing module makes full use of the concentration distribution ratio of copper and nickel in different phases to wash the first oil phase, and the single washing efficiency reaches more than 80%. After multiple washings, the second oil phase and the first washing water phase are obtained, and the second oil phase enters the first stripping module to obtain the first stripping water phase, and multiple stripping operations are performed to recover more copper resources. After the first water phase is mixed with the first washing water phase, a second salt solution is obtained and enters the second extraction module; S6, the first stripping water phase enters the crystallization module, and uses high heat to separate salt and water to obtain a copper-containing salt product; S7, the second extraction module uses a nickel ion extractant to extract nickel from the second salt solution, the ratio of the water phase to the oil phase is 1:1, and after extraction, a third oil phase containing more nickel and less copper and a second water phase are obtained, the second oil phase enters the second washing module, and the third oil phase is washed using the concentration distribution ratio of copper and nickel in different phases, and the single washing efficiency reaches more than 78%. After multiple washings, a fourth oil phase and a second washing water phase are obtained, and the fourth oil phase enters the second stripping module to obtain a second stripping water phase, and multiple stripping operations are performed to recover more nickel resources; S8. The second stripping water phase enters the crystallization module, and uses high heat to separate salt and water to obtain a nickel-containing salt product.

[0006] In a preferred embodiment of the present invention, in step S2, the pH value in the first pH adjustment tank is adjusted to 3-5.

[0007] In a preferred embodiment of the present invention, in step S2, the concentration of the suspended matter is controlled to be below 10 mg / L, preferably, below 5 mg / L.

[0008] In a preferred embodiment of the present invention, in step S3, the enrichment concentration is above 100,000 mg / L.

[0009] In a preferred embodiment of the present invention, in step S4, in the first extraction mold, the pH is controlled at 4-5, and the extraction time is 0.5h.

[0010] In a preferred embodiment of the present invention, in step S5, in the first stripping module, the pH value is adjusted to 2 and the stripping efficiency is 85%.

[0011] In a preferred embodiment of the present invention, in step S7, in the second extraction module, the pH is controlled at 4-5, and the extraction time is 0.75h.

[0012] In a preferred embodiment of the present invention, in step S7, in the second stripping module, the pH value is adjusted to 1-2, and the stripping efficiency is 81%.

[0013] In a preferred embodiment of the present invention, the copper ion extractant is one of P204, hydroxamic acid, and LY202403, and the diluent of the copper ion extractant is one of sulfonated kerosene, n-hexane, and n-octane.

[0014] In a preferred embodiment of the present invention, the nickel ion extractant is one of P507, phosphate ester, and LY202407, and the diluent of the nickel ion extractant is one of sulfonated kerosene, n-hexane, and n-octane.

[0015] The beneficial effects of the present invention are as follows: the present invention discloses a method for separating and purifying low-concentration copper and nickel, and configures an aqueous phase detergent containing certain copper and nickel ions according to the distribution coefficients of copper and nickel in different phases, and achieves the purpose of separating and purifying copper and nickel through multiple washings, with good purification effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work, among which: Figure 1 The figure is a schematic diagram of the process of the method for separating and purifying low-concentration copper and nickel of the present invention. DETAILED DESCRIPTION

[0017] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0018] The embodiment of the present invention includes: a method for separating and purifying low-concentration copper and nickel, comprising the following steps: S1. Low-concentration copper and nickel-containing wastewater passes through a coarse screen to remove large impurities in the wastewater to protect subsequent process modules and obtain the first wastewater.

[0019] S2. Adjust the pH value of the first wastewater to around 5, and initially precipitate the interfering factors that can form precipitation under weak acidic conditions. The pH adjuster and eluent (acidic) can be screened according to the needs of the terminal salt product, and can be one or more of sulfuric acid, nitric acid, hydrochloric acid or organic acid. Filter through a ceramic ultrafiltration membrane to remove interfering factors (precipitated substances), which is also to remove suspended solids (SS) in the first wastewater. The SS concentration is controlled below 10 mg / L, and it is best to control it to below 5 mg / L to obtain the second wastewater. The ceramic ultrafiltration membrane is the main module for removing SS, which requires considerable acid and corrosion resistance, and inert materials are better. Therefore, the ceramic membrane of silicon carbide material has the most stable new energy. SS removal is crucial to the protection of subsequent process modules. Therefore, the selection of SS removal module is very important, and ceramic ultrafiltration is recommended.

[0020] S3. The second wastewater is enriched with copper and nickel ions through a resin adsorption module, and the enrichment concentration reaches at least 50,000 mg / L (the composite concentration of copper and nickel in the eluent, i.e., the sum of the concentrations of copper and nickel ions), with 100,000 mg / L or more being the best. The adsorption resin is eluted with a strong acid to obtain a first salt solution containing high concentrations of copper and nickel ions.

[0021] S4, the first salt solution enters the first extraction module, and the copper ions in the first salt solution are extracted using a high-efficiency copper ion extractant, the ratio of the aqueous phase to the oil phase is 2:1, the pH is controlled at 4-5, the extraction time is 0.5h, and a first oil phase and a first aqueous phase containing more copper and less nickel are obtained.

[0022] S5. The first oil phase enters the first washing module, and the concentration distribution ratio of copper and nickel in different phases is fully utilized to wash the oil phase. The single washing efficiency reaches more than 80%, that is, after the nickel in the oil phase is washed, the concentration of nickel ions will be reduced by 80%. According to the purity requirements of the terminal product, multiple washings can be performed to obtain the second oil phase and the first washing water phase to meet the purification requirements. The second oil phase enters the first stripping module, and the pH value is adjusted to about 2 to obtain the first stripping water phase. The stripping efficiency of each time is 85%. According to economic considerations, multiple stripping operations can be performed to achieve as much recovery of copper resources as possible.

[0023] S6. The first stripping water phase enters the crystallization module, and uses high heat to separate salt and water to obtain crystalline salt, i.e., copper-containing salt product.

[0024] S7. After the first aqueous phase and the first washing aqueous phase are mixed, a second salt solution is obtained, and the solution enters the second extraction module, wherein the stripping agent used is an aqueous solution that maintains a certain pH value, usually a pH value between 2-3, and a high-efficiency nickel extractant is used to extract nickel. The ratio of the aqueous phase to the oil phase is 1:1, the pH is controlled at about 4.5, and the extraction time is 0.75h to obtain a third oil phase containing more nickel and less copper and a second aqueous phase.

[0025] S8. The third oil phase enters the second washing module, and the concentration distribution ratio of copper and nickel in different phases is fully utilized to wash the third oil phase. The single washing efficiency reaches more than 78%, that is, after the copper in the oil phase is washed, the concentration of copper ions will be reduced by 78%. According to the purity requirements of the terminal product, multiple washings can be performed to obtain the fourth oil phase and the second washing water phase to meet the purification requirements. The fourth oil phase enters the stripping module, and the pH value is adjusted to about 1.5 to obtain the second stripping water phase. The stripping efficiency of each time is 81%. According to economic considerations, multiple stripping operations can be performed to achieve as much nickel resource recovery as possible.

[0026] S9. The second stripping water phase can enter the crystallization module, and use high heat to separate the salt and water to obtain crystalline salt, that is, a nickel-containing salt product.

[0027] Specifically, the copper ion extractant is one of P204, hydroxamic acid, and LY202403, the diluent of the copper ion extractant is one of sulfonated kerosene, n-hexane, and n-octane, the nickel ion extractant is one of P507, phosphate, and LY202407, and the diluent of the nickel ion extractant is one of sulfonated kerosene, n-hexane, and n-octane. According to the distribution coefficients of copper and nickel in different phases, the present invention configures an aqueous phase detergent containing certain copper and nickel ions. For example, when washing nickel ions, that is, when nickel ions need to be transferred from the oil phase to the water phase, the configured detergent contains a considerable concentration of copper ions to reduce the transfer of copper ions from the oil phase to the water phase. Since the detergent does not contain nickel ions, the nickel ions in the oil phase need to be transferred to the water phase through multiple washings to achieve the purpose of purification.

[0028] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for separating and purifying low-concentration copper and nickel, characterized in that: The steps include: S1, passing low-concentration copper and nickel-containing wastewater through a coarse screen, the coarse screen removes coarse impurities in the wastewater to obtain first wastewater, and the first wastewater is discharged into a first pH adjustment tank; S2, the first pH adjustment tank adjusts the pH value of the first wastewater to weak acidity to exclude interference factors that may form precipitation for initial precipitation, and uses a ceramic ultrafiltration membrane to filter and remove suspended matter in the interference factors, and controls the concentration of the suspended matter to below 10 mg / L to obtain the second wastewater; S3, the resin adsorption module enriches the copper and nickel ions in the second wastewater, and the enrichment concentration reaches at least 50000 mg / L, and the adsorption resin is eluted with a strong acid to obtain a first salt solution containing high concentrations of copper and nickel ions; S4, the first extraction module uses a copper ion extractant to extract the first salt solution, and the ratio of the water phase to the oil phase during extraction is 2:1, to obtain a first oil phase and a first water phase containing more copper and less nickel, and the first oil phase enters the first washing module; S5, the first washing module makes full use of the concentration distribution ratio of copper and nickel in different phases to wash the first oil phase, and the single washing efficiency reaches more than 80%. After multiple washings, the second oil phase and the first washing water phase are obtained, and the second oil phase enters the first stripping module to obtain the first stripping water phase, and multiple stripping operations are performed to recover more copper resources. After the first water phase is mixed with the first washing water phase, a second salt solution is obtained and enters the second extraction module; S6, the first stripping water phase enters the crystallization module, and uses high heat to separate salt and water to obtain a copper-containing salt product; S7, the second extraction module uses a nickel ion extractant to extract nickel from the second salt solution, the ratio of the water phase to the oil phase is 1:1, and after extraction, a third oil phase containing more nickel and less copper and a second water phase are obtained, the second oil phase enters the second washing module, and the third oil phase is washed using the concentration distribution ratio of copper and nickel in different phases, and the single washing efficiency reaches more than 78%. After multiple washings, a fourth oil phase and a second washing water phase are obtained, and the fourth oil phase enters the second stripping module to obtain a second stripping water phase, and multiple stripping operations are performed to recover more nickel resources; S8. The second stripping water phase enters the crystallization module, and uses high heat to separate salt and water to obtain a nickel-containing salt product.

2. The method for separating and purifying low-concentration copper and nickel according to claim 1, characterized in that: In step S2, the pH value in the first pH adjustment tank is adjusted to 3-5.

3. The method for separating and purifying low-concentration copper and nickel according to claim 1, characterized in that: In step S2, the concentration of the suspended matter is controlled to be below 10 mg / L, preferably, below 5 mg / L.

4. The method for separating and purifying low-concentration copper and nickel according to claim 1, characterized in that: In step S3, the enrichment concentration is above 100,000 mg / L.

5. The method for separating and purifying low-concentration copper and nickel according to claim 1, characterized in that: In step S4, in the first extraction mold, the pH is controlled at 4-5, and the extraction time is 0.5 h.

6. The method for separating and purifying low-concentration copper and nickel according to claim 1, characterized in that: In step S5, in the first stripping module, the pH value is adjusted to 2, and the stripping efficiency is 85%.

7. The method for separating and purifying low-concentration copper and nickel according to claim 1, characterized in that: In step S7, in the second extraction module, the pH is controlled at 4-5, and the extraction time is 0.75 h.

8. The method for separating and purifying low-concentration copper and nickel according to claim 1, characterized in that: In step S7, in the second stripping module, the pH value is adjusted to 1-2, and the stripping efficiency is 81%.

9. The method for separating and purifying low-concentration copper and nickel according to claim 1, characterized in that: The copper ion extractant is one of P204, hydroxamic acid and LY202403, and the diluent of the copper ion extractant is one of sulfonated kerosene, n-hexane and n-octane.

10. The method for separating and purifying low-concentration copper and nickel according to claim 1, characterized in that: The nickel ion extractant is one of P507, phosphate ester and LY202407, and the diluent of the nickel ion extractant is one of sulfonated kerosene, n-hexane and n-octane.

Images