A process for treating and recovering sodium sulfate wastewater containing nickel, cobalt and manganese

Abstract

The invention relates to a sodium sulfate wastewater treatment and recovery process containing nickel, cobalt and manganese, and belongs to the technical field of wastewater treatment and metal smelting. The invention relates to a sodium sulfate wastewater treatment and recovery process containing nickel, cobalt and manganese, and the specific steps are as follows: (1) the treated C272 manganese extraction residual solution P507 cobalt extraction residual solution P507 nickel extraction residual solution are mixed and filtered and deoiled for standby use; (2) the mixed solution in step (1) is subjected to ion exchange to obtain sodium sulfate wastewater and saturated resin; (3) the sodium sulfate wastewater in step (2) is concentrated through a reverse osmosis membrane to obtain concentrated sodium sulfate and fresh water; (4) the concentrated sodium sulfate solution in step (3) is evaporated through an MVR evaporator to obtain sodium sulfate crystal salt solution and condensed water; (5) the sodium sulfate crystal salt solution in step (4) is separated into sodium sulfate salt by a centrifuge; (6) the saturated resin in step (2) is regenerated to obtain concentrated nickel sulfate; (7) the concentrated nickel sulfate in step (6) can be respectively obtained by step-by-step precipitation and filtration to obtain cobalt salt, nickel salt and manganese salt.

Description

[0001] Technical Field The present invention relates to a sodium sulfate wastewater treatment and resource recovery process containing heavy metals, and in particular to a sodium sulfate wastewater treatment and recovery process containing nickel, cobalt and manganese, belonging to the technical field of wastewater treatment and metal smelting. Background Technology When cobalt series products and ternary precursors of lithium battery positive electrode materials are produced using ternary battery waste as raw materials, a large amount of raffinate wastewater is generated in the post-processing processes of the leaching section, such as C272 manganese extraction, P507 cobalt extraction, and P507 nickel extraction. The above three types of raffinate wastewater mainly contain heavy metal nickel (50-200 mg / L), cobalt (1-50 mg / L), manganese (100-500 mg / L) and other valuable metals and sodium sulfate salt (30000-50000 mg / L), which are high-salt inorganic wastewater. If directly discharged, it will cause serious pollution of surface water, groundwater and even soil, which is also a waste of limited resources; the traditional process of the above-mentioned heavy metal wastewater is usually classified for treatment or filtered after step-by-step precipitation under different pH conditions. Because the concentration of high-priced metal nickel and cobalt in the above-mentioned slurry is relatively low, and it contains other impurities without direct recovery value, the metal ions and total salt content of the treated wastewater cannot meet the current national and industry water pollutant emission standards, and the nickel-containing filter residue is a Class I pollutant (hazardous waste), and the treatment cost is high. Summary of the invention

[0002] The object of the present invention is to provide a process for treating and recovering sodium sulfate wastewater containing nickel, cobalt and manganese to solve the problems raised in the above background technology. The specific scheme of the present invention is as follows:

[0003] A process for treating and recovering sodium sulfate wastewater containing nickel, cobalt and manganese:

[0004] (1) The pretreated C272 manganese extraction residual solution, P507 cobalt extraction residual solution, and P507 nickel extraction residual solution are mixed, and the mixed solution is further finely filtered and deoiled before use.

[0005] (2) Three ion exchangers are used in two cases and one is used as standby. 2BV of resin volume of 8% sulfuric acid solution is passed through the resin column at a flow rate of 15m³ / h and in a bottom-in-middle-out manner. The concentrated nickel sulfate regeneration liquid with a pH value ≥ 2 is discharged into the concentrated nickel sulfate tank; the dilute nickel sulfate with a pH value < 2 is discharged into the dilute nickel sulfate tank for standby. After the regeneration is completed, it is rinsed with pure water until the pH value is > 6, at which time the resin is H-type; then 2.15BV of resin volume of 4% sodium hydroxide solution is passed through the resin column in a bottom-in-top-out manner, and the transformation liquid with a pH value ≤ 11 is discharged into the concentrated nickel sulfate tank; the dilute alkali liquid with a pH value > 11 is discharged into the alkali washing water tank for standby. After the transformation is completed, it is rinsed with pure water until the pH is < 10. After the above regeneration and transformation, the ion exchanger is ready for standby.

[0006] (3) The mixed liquid obtained in step (1) is subjected to ion exchange adsorption by the ion exchange resin regenerated and transformed in step (2). The sodium sulfate wastewater obtained after adsorption enters the post-ion exchange liquid tank. The total manganese online analyzer during the adsorption process detects the post-adsorption solution. When Mn 2+ The content is greater than 0.5 mg / L. At this time, the resin is saturated with adsorption. The feed liquid is switched to enter the standby ion exchanger for operation, and the resulting resin is saturated with adsorption.

[0007] (4) The sodium sulfate wastewater produced in step (3) is further concentrated and desalted by a RO reverse osmosis device to obtain a concentrated sodium sulfate solution. At the same time, the reverse osmosis fresh water is obtained and transported to a pure water station for use as raw water.

[0008] (5) The concentrated sodium sulfate solution obtained in step (4) is cyclically evaporated through an MVR evaporator until the sodium sulfate solution is saturated and precipitated to obtain a sodium sulfate crystal salt solution. The high-temperature condensate produced by evaporation is transported to a pure water station for use as raw water after utilizing the waste heat through an MVR preheater.

[0009] (6) The saturated sodium sulfate crystal solution obtained in step (5) is centrifuged to obtain sodium sulfate salt.

[0010] (7) The saturated resin obtained in step (3) is regenerated and transformed through step (2).

[0011] (8) Step (7) Regeneration and transformation to obtain concentrated nickel sulfate solution can be carried out through step-by-step precipitation and filtration to obtain cobalt salt, nickel salt and manganese salt. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 The present invention is a process flow diagram of a sodium sulfate wastewater treatment and resource recovery process containing nickel, cobalt and manganese. DETAILED DESCRIPTION

[0013] To better illustrate the purpose and technical solution of the present invention, the present invention will be further described below in conjunction with specific embodiments. It should be understood by those skilled in the art that the following specific embodiments are only used to explain the present invention and are not intended to limit the present invention.

[0014] Example 1: A process for treating and recycling sodium sulfate wastewater containing nickel, cobalt and manganese

[0015] (1) The pre-treated C272 manganese extraction residual solution, P507 cobalt extraction residual solution, and P507 nickel extraction residual solution are combined into the pre-ion exchange liquid tank. The mixed liquid is further finely filtered and deoiled before use. The obtained mixed liquid composition (Ni 2+ :96mg / L,Co 2+ :28mg / L,Mn 2+ :352mg / L,Na + :32750mg / L)

[0016] (2) Three ion exchangers are used in two cases and one is used as a standby. 8% sulfuric acid solution with a volume of 2BV resin is used at a flow rate of 15m³ / h and in a bottom-in-middle-out manner to pass through the resin. The concentrated nickel sulfate regeneration liquid with a pH value ≥ 2 is discharged into the concentrated nickel sulfate tank; when the pH value of the discharged regeneration liquid is less than 2, the dilute nickel sulfate regeneration liquid is discharged into the dilute nickel sulfate tank for standby in a bottom-in-up-out manner. After the regeneration is completed, it is rinsed with pure water until the pH is greater than 6, at which time the resin is H type; then 4% sodium hydroxide solution with a volume of 2.15BV resin is used to convert the H type resin to Na type, and the ion exchange column after regeneration and washing is transformed in a bottom-in-up-out manner. The transformation liquid with a pH value of ≤11 discharged from the front stage of the transformation process is discharged into the concentrated nickel sulfate tank; the dilute alkali liquid with a pH value of >11 is discharged into the alkali washing water tank for standby. After the transformation is completed, it is rinsed with pure water until the pH is less than 10. After the above regeneration and transformation, the ion exchanger is ready for standby.

[0017] (3) The mixed liquid obtained in step (1) is subjected to ion exchange adsorption by the ion exchange resin regenerated and transformed in step (2), and the sodium sulfate wastewater (Na + :31480mg / L) enters the ion exchange tank, and the total manganese online analyzer detects the adsorption solution during the adsorption process. 2+ The content is greater than 0.5 mg / L. At this time, the resin is saturated with adsorption. The feed liquid is switched to enter the standby ion exchanger for operation, and the resulting resin is saturated with adsorption.

[0018] (4) The sodium sulfate wastewater produced in step (3) is further concentrated and desalted by a RO reverse osmosis device to obtain a concentrated sodium sulfate solution (Na + :77650mg / L), and obtain reverse osmosis fresh water (Na + : 1283mg / L) is transported to the pure water station for use as raw water.

[0019] (5) The concentrated sodium sulfate solution in step (4) is cyclically evaporated through an MVR evaporator until the sodium sulfate solution is saturated and precipitated to obtain a sodium sulfate crystal salt solution. The high-temperature condensate produced by evaporation is transported to a pure water station for use as raw water after utilizing the waste heat through an MVR preheater.

[0020] (6) The saturated sodium sulfate crystal solution obtained in step (5) is centrifuged to obtain sodium sulfate salt.

[0021] (7) The saturated resin obtained in step (3) is regenerated and transformed through step (2).

[0022] (8) The concentrated nickel sulfate solution obtained by regeneration and transformation in step (7) can be used to obtain cobalt salt, nickel salt and manganese salt through step-by-step precipitation and filtration.

[0023] Test result 1:

[0024] Composition test sample pH (dimensionless) <![CDATA[Ni 2+ (mg / L)]]> <![CDATA[Co 2+ (mg / L)]]> <![CDATA[Mn 2+ (mg / L)]]> <![CDATA[Na + (mg / L)]]> Before ion exchange 4.8 96 28 352 32750 After ion exchange 5.2 0.03 0.04 0.07 31480 Concentrated nickel sulfate solution 3.6 12775 3286 14342 10610 RO concentrate 5.9 0.10 0.12 0.16 77650 Composition test sample pH (dimensionless) <![CDATA[Ni 2+ (mg / L)]]> <![CDATA[Co 2+ (mg / L)]]> <![CDATA[Mn 2+ (mg / L)]]> <![CDATA[Na + (mg / L) <!-- 2 -->]]> RO Fresh Water 5.0 - - - 1283 MVR condensate 7.1 - - - 10 Composition test sample Moisture content (%) <![CDATA[Ni 2+ (g / kg)]]> <![CDATA[Co 2+ (g / kg)]]> <![CDATA[Mn 2+ (g / kg)]]> <![CDATA[Na + (g / kg)]]> Sodium sulfate 4.7 0.00053 0.00031 0.00076 386

[0025] Example 2: A process for treating and recycling sodium sulfate wastewater containing nickel, cobalt and manganese

[0026] (1) The pre-treated C272 manganese extraction residual solution, P507 cobalt extraction residual solution, and P507 nickel extraction residual solution are combined into the pre-ion exchange liquid tank. The mixed liquid is further finely filtered and deoiled before use. The obtained mixed liquid composition (Ni 2+ :148mg / L,Co 2+ :36mg / L,Mn 2+ :412mg / L,Na + :40961mg / L)

[0027] (2) Three ion exchangers are used in two cases and one is used as a standby. 8% sulfuric acid solution with a volume of 2BV resin is passed through the resin at a flow rate of 15m³ / h in a bottom-in-middle-out manner. The concentrated nickel sulfate regeneration liquid with a pH value ≥ 2 is discharged into the concentrated nickel sulfate tank. When the pH value of the discharged regeneration liquid is <2, the dilute nickel sulfate regeneration liquid is discharged into the dilute nickel sulfate tank for standby in a bottom-in-up-out manner.

[0028] After regeneration, rinse with pure water until pH>6, at which time the resin is H type; then use 2.15BV of resin volume of 4% sodium hydroxide solution to convert the H type resin to Na type, and use the bottom-in and top-out method to transform the ion exchange column after regeneration and washing. The transformation liquid with a pH value of ≤11 discharged from the front of the transformation process is discharged into the concentrated nickel sulfate tank; the dilute alkali liquid with a pH value of>11 is discharged into the alkali washing water tank for standby. After the transformation is completed, rinse with pure water until pH<10, and the ion exchanger after the above regeneration and transformation is ready for use.

[0029] (3) The mixed liquid obtained in step (1) is subjected to ion exchange adsorption by the ion exchange resin regenerated and transformed in step (2), and the sodium sulfate wastewater (Na + :36274mg / L) enters the ion exchange tank, and the total manganese online analyzer detects the adsorption solution during the adsorption process. 2+ The content is greater than 0.5 mg / L. At this time, the resin is saturated with adsorption. The feed liquid is switched to enter the standby ion exchanger for operation, and the resulting resin is saturated with adsorption.

[0030] (4) The sodium sulfate wastewater produced in step (3) is further concentrated and desalted by a RO reverse osmosis device to obtain a concentrated sodium sulfate solution (Na + :89730mg / L), and obtain reverse osmosis fresh water (Na + : 1579mg / L) is transported to the pure water station for use as raw water.

[0031] (5) The concentrated sodium sulfate solution in step (4) is cyclically evaporated through an MVR evaporator until the sodium sulfate solution is saturated and precipitated to obtain a sodium sulfate crystal salt solution. The high-temperature condensate produced by evaporation is transported to a pure water station for use as raw water after utilizing the waste heat through an MVR preheater.

[0032] (6) The saturated sodium sulfate crystal solution obtained in step (5) is centrifuged to obtain sodium sulfate salt.

[0033] (7) The saturated resin obtained in step (3) is regenerated and transformed through step (2).

[0034] (8) Step (7) Regeneration and transformation to obtain concentrated nickel sulfate solution can be used to obtain cobalt salt, nickel salt and manganese salt through step-by-step precipitation and filtration.

[0035] Test result 2:

[0036] Composition test sample pH (dimensionless) <![CDATA[Ni 2+ (mg / L)]]> <![CDATA[Co 2+ (mg / L)]]> <![CDATA[Mn 2+ (mg / L)]]> <![CDATA[Na + (mg / L)]]> Before ion exchange 4.4 148 36 412 40961 After ion exchange 4.8 0.04 0.03 0.06 36274 Concentrated nickel sulfate solution 3.5 13066 2710 13870 11860 RO concentrate 5.6 0.11 0.13 0.14 89730 Composition test sample pH (dimensionless) <![CDATA[Ni 2+ (mg / L)]]> <![CDATA[Co 2+ (mg / L)]]> <![CDATA[Mn 2+ (mg / L)]]> <![CDATA[Na + (mg / L)]]> RO Fresh Water 4.9 - - - 1579 MVR condensate 7.1 - - - 10 Composition test sample Moisture content (%) <![CDATA[Ni 2+ (g / kg)]]> <![CDATA[Co 2+ (g / kg)]]> <![CDATA[Mn 2+ (g / kg)]]> <![CDATA[Na + (g / kg)]]> Sodium sulfate 4.6 0.00064 0.00038 0.00079 402

[0037] Example 3: A process for treating and recycling sodium sulfate wastewater containing nickel, cobalt and manganese

[0038] (1) The pre-treated C272 manganese extraction residual solution, P507 cobalt extraction residual solution, and P507 nickel extraction residual solution are combined into the pre-ion exchange liquid tank, and the mixed liquid is further finely filtered and deoiled before use. The obtained mixed liquid composition (Ni 2+ :125mg / L,Co 2+ :41mg / L,Mn 2+ :457mg / L,Na + :36890mg / L)

[0039] (2) Three ion exchangers are used in two cases and one is used as a standby. 8% sulfuric acid solution with a volume of 2BV resin is passed through the resin at a flow rate of 15m³ / h in a bottom-in-middle-out manner. The concentrated nickel sulfate regeneration liquid with a pH value ≥ 2 is discharged into the concentrated nickel sulfate tank; when the pH value of the discharged regeneration liquid is less than 2, the dilute nickel sulfate regeneration liquid is discharged into the dilute nickel sulfate tank for standby in a bottom-in-up-out manner. After the regeneration is completed, it is rinsed with pure water until the pH is greater than 6, at which time the resin is H type; then 4% sodium hydroxide solution with a volume of 2.15BV resin is used to convert the H type resin to Na type, and the ion exchange column after regeneration and washing is transformed in a bottom-in-up-out manner. The transformation liquid with a pH value of ≤11 discharged from the front stage of the transformation process is discharged into the concentrated nickel sulfate tank; the dilute alkali liquid with a pH value of >11 is discharged into the alkali washing water tank for standby. After the transformation is completed, it is rinsed with pure water until the pH is less than 10. After the above regeneration and transformation, the ion exchanger is ready for standby.

[0040] (3) The mixed liquid obtained in step (1) is subjected to ion exchange adsorption by the ion exchange resin regenerated and transformed in step (2), and the sodium sulfate wastewater (Na +:32560mg / L) enters the ion exchange tank, and the total manganese online analyzer detects the adsorption solution during the adsorption process. 2+ The content is greater than 0.5 mg / L. At this time, the resin is saturated with adsorption. The feed liquid is switched to enter the standby ion exchanger for operation, and the resulting resin is saturated with adsorption.

[0041] (4) The sodium sulfate wastewater produced in step (3) is further concentrated and desalted by a RO reverse osmosis device to obtain a concentrated sodium sulfate solution (Na + :79622mg / L), and obtain reverse osmosis fresh water (Na + : 1369mg / L) is transported to the pure water station for use as raw water.

[0042] (5) The concentrated sodium sulfate solution in step (4) is cyclically evaporated through an MVR evaporator until the sodium sulfate solution is saturated and precipitated to obtain a sodium sulfate crystal salt solution. The high-temperature condensate produced by evaporation is transported to a pure water station for use as raw water after utilizing the waste heat through an MVR preheater.

[0043] (6) The saturated sodium sulfate crystal solution obtained in step (5) is centrifuged to obtain sodium sulfate salt.

[0044] (7) The saturated resin obtained in step (3) is regenerated and transformed through step (2).

[0045] (8) Step (7) Regeneration and transformation to obtain concentrated nickel sulfate solution can be used to obtain cobalt salt, nickel salt and manganese salt through step-by-step precipitation and filtration.

[0046] Test result 3:

[0047] Composition test sample pH (dimensionless) <![CDATA[Ni 2+ (mg / L)]]> <![CDATA[Co 2+ (mg / L)]]> <![CDATA[Mn 2+ (mg / L)]]> <![CDATA[Na + (mg / L)]]> Before ion exchange 4.7 125 41 457 36890 After ion exchange 4.9 0.03 0.02 0.05 32560 Concentrated nickel sulfate solution 3.6 13828 3143 14382 12775 RO concentrate 0.10 0.12 0.13 79622 Composition test sample pH (dimensionless) <![CDATA[Ni 2+ (mg / L)]]> <![CDATA[Co 2+ (mg / L)]]> <![CDATA[Mn 2+ (mg / L)]]> <![CDATA[Na + (mg / L)]]> RO Fresh Water 4.9 - - - 1369 MVR condensate 7.0 - - - 18 Composition test sample Moisture content (%) <![CDATA[Ni 2+ (g / kg)]]> <![CDATA[Co 2+ (g / kg)]]> <![CDATA[Mn 2+ (g / kg)]]> <![CDATA[Na + (g / kg)]]> Sodium sulfate 4.7 0.00073 0.00044 0.00085 389

Claims

1. A process for treating and recovering sodium sulfate wastewater containing nickel, cobalt and manganese, characterized in that: The specific steps are as follows: (1) mixing the pretreated C272 manganese extraction residual solution, P507 cobalt extraction residual solution and P507 nickel extraction residual solution, and further fine filtering and degreasing the mixed solution for later use; (2) Three ion exchangers were used as two and one as standby. Each was treated with 2 BV of resin volume and 8% sulfuric acid solution at 15 m 3 / h flow rate and pass through the resin column in a bottom-in-middle-out manner, discharge concentrated nickel sulfate regeneration liquid with a pH value ≥ 2, and discharge it into a concentrated nickel sulfate tank; dilute nickel sulfate with a pH value < 2 is discharged into a dilute nickel sulfate tank for standby use, and after the regeneration is completed, rinse with pure water to a pH value of > 6, at which time the resin is H-type; then pass 2.15BV of resin volume of 4% sodium hydroxide solution through the resin column in a bottom-in-top-out manner, and discharge the transformation liquid with a pH value ≤ 11 into a concentrated nickel sulfate tank; dilute alkali solution with a pH value > 11 into an alkali washing water tank for standby use, and after the transformation is completed, rinse with pure water to a pH value of < 10, completing the above regeneration and transformation, and the ion exchanger is ready for use; (3) The mixed liquid obtained in step (1) is subjected to ion exchange adsorption by the ion exchange resin regenerated and transformed in step (2), and the sodium sulfate wastewater obtained after adsorption enters the post-ion exchange liquid tank. The total manganese online analyzer during the adsorption process detects the post-adsorption solution. When Mn 2+ Content>0.5mg / L, at this time, the resin is saturated with adsorption, and the feed liquid is switched to the standby ion exchanger for operation, and the resulting adsorption saturated resin; (4) The sodium sulfate wastewater produced in step (3) is further concentrated and desalted by a RO reverse osmosis device to obtain a concentrated sodium sulfate solution, and the reverse osmosis fresh water is transported to a pure water station for use as raw water; (5) The concentrated sodium sulfate solution obtained in step (4) is cyclically evaporated through an MVR evaporator until the sodium sulfate solution is saturated and precipitated to obtain a sodium sulfate crystal salt solution. The high-temperature condensate produced by evaporation is transported to a pure water station for use as raw water after utilizing the waste heat through an MVR preheater; (6) centrifuging the saturated sodium sulfate crystal solution obtained in step (5) to obtain sodium sulfate salt; (7) regenerating and transforming the saturated resin obtained in step (3) through step (2); (8) The concentrated nickel sulfate solution obtained by regeneration and transformation in step (7) can obtain cobalt salt, nickel salt and manganese salt through step-by-step precipitation and filtration. The ion exchange resin in step (2) is D851 macroporous styrene structure chelating resin. A part of the dilute nickel sulfate in step (2) is used to prepare 8% sulfuric acid, and the rest is used to adjust the pH value of the mixed solution in step (1) to ≥4.

2. A part of the washing alkali water is used to prepare 4% sodium hydroxide, and the rest is used to adjust the pH value of the mixed solution in step (1) to ≥4.

2.

2. A process for treating and recovering sodium sulfate wastewater containing nickel, cobalt and manganese as claimed in claim 1, characterized in that: The fine filtration in step (1) adopts a disc-type self-cleaning filter, and the oil removal adopts a resin ZGSO107 oil removal filter.

3. A process for treating and recovering sodium sulfate wastewater containing nickel, cobalt and manganese as claimed in claim 1, characterized in that: The RO device in step (4) is a high-pressure reverse osmosis device with energy recovery.

4. A process for treating and recovering sodium sulfate wastewater containing nickel, cobalt and manganese as claimed in claim 1, characterized in that: In the step (5), the evaporation temperature of the MVR evaporator is 90° C., and the vacuum degree at the evaporation temperature is -0.03 MPa.

5. A process for treating and recovering sodium sulfate wastewater containing nickel, cobalt and manganese as claimed in claim 1, characterized in that: The centrifuge in step (6) is a LWL type horizontal screw centrifuge.

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