Regeneration system for chromium resource in hexavalent chromium-containing wastewater

Abstract

The utility model discloses a retrogradation system for chromium resources in hexavalent chromium-containing wastewater. The retrogradation system comprises an impurity removal mechanism, an acidification mechanism, an ion exchange mechanism and a crystallization mechanism, chromium-containing wastewater and alkali liquor are introduced into the impurity removal mechanism, so that impurity metal ions in the chromium-containing wastewater are precipitated; the acidification mechanism is communicated with the impurity removal mechanism, and is used for introducing acid liquor into the supernate so as to adjust the pH value of the supernate; the ion exchange mechanism is communicated with the acidification mechanism, the ion exchange mechanism can adsorb hexavalent chromium ions in the supernate, and an alkali desorption solution can be introduced into the ion exchange mechanism so as to desorb and regenerate the adsorbed hexavalent chromium ions into a chromium salt solution; the crystallization mechanism is communicated with the ion exchange mechanism, the chromium salt solution can be introduced into the crystallization mechanism, and the crystallization mechanism can concentrate and dry the chromium salt solution to obtain crystallized chromium salt. According to the chromium resource retrogradation system in the hexavalent chromium-containing wastewater, provided by the utility model, the recovery content of hexavalent chromium is increased.

Description

TECHNICAL FIELD

[0001] The utility model relates to wastewater resource recovery technical field especially relates to a kind of chromium resource regeneration system in containing hexavalent chromium wastewater. BACKGROUND

[0002] Chromium metal has good corrosion resistance, can keep its luster for a long time, good wear resistance, heat resistance, high hardness and other performances, chromium metal has a wide application in electroplating (such as electroplating hard chromium, electroplating decorative chromium, plating zinc chromium passivation, etc.); In the electroplating process, due to the rinsing of plated parts, the scrapping of bath solution, the replacement and cleaning of filter cloth filter core of plating solution filter machine, etc., a certain amount of chromium-containing wastewater will be produced, and the main pollution factors in chromium-containing wastewater include Cr2O7 2- , Cr 3+ , Zn 2+ , Cu 2+ , Fe 3+ , Ni 2+ , etc.; The conventional chromium water treatment method is reduction-neutralization flocculation method, Cr2O7 2- is reduced to Cr 3+ by adding a reducing agent under acidic conditions, and then the pH value of the wastewater is adjusted by adding alkali to convert all metal ions into corresponding hydroxides to remove them, but the chromium mud obtained by the method has complex composition and low chromium content, and is not easy to be reused. SUMMARY

[0003] The utility model aims at providing a kind of chromium resource regeneration system in containing hexavalent chromium wastewater to solve the problems existing in the prior art, and improve the recovery content of hexavalent chromium.

[0004] To achieve the above object, the utility model provides the following scheme:

[0005] The utility model provides a kind of chromium resource regeneration system in containing hexavalent chromium wastewater, including impurity removal mechanism, acidification mechanism, ion exchange mechanism and crystallization mechanism;Impurity removal mechanism is used to pass into chromium-containing wastewater and lye, and the impurity metal ions in chromium-containing wastewater are precipitated by mixing chromium-containing wastewater and lye in the impurity removal mechanism;The supernatant after mixing of chromium-containing wastewater and lye enters the acidification mechanism, and the acidification mechanism is also used to pass into acid liquor into the supernatant to be able to adjust the pH of supernatant;Ion exchange mechanism is communicated with the acidification mechanism, and the supernatant after acidification can enter the ion exchange mechanism, the ion exchange mechanism can adsorb hexavalent chromium ions in the supernatant, and base elution liquid can also be passed into the ion exchange mechanism to regenerate the adsorbed hexavalent chromium ions into chromium salt solution;Crystallization mechanism is communicated with the ion exchange mechanism, and chromium salt solution can be passed into the crystallization mechanism, and the crystallization mechanism can concentrate and dry chromium salt solution to obtain crystalline chromium salt.

[0006] Preferably, the impurity removal mechanism comprises a wastewater conditioning tank, a sedimentation tank and a lye tank, the sedimentation tank and the lye tank are both in communication with the wastewater conditioning tank, the wastewater conditioning tank is used for introducing the wastewater containing chromium, the lye tank is used for introducing lye into the wastewater conditioning tank, the mixture in the wastewater conditioning tank is introduced into the sedimentation tank, the sedimentation tank is in communication with the acidification mechanism, and the supernatant in the sedimentation tank is introduced into the acidification mechanism.

[0007] Preferably, the acidification mechanism comprises a supernatant conditioning tank and an acid tank, the supernatant conditioning tank is in communication with the impurity removal mechanism and is used for introducing the supernatant, the acid tank is in communication with the supernatant conditioning tank and is used for introducing acid into the supernatant conditioning tank; and the supernatant conditioning tank is also in communication with the ion exchange mechanism.

[0008] Preferably, the ion exchange mechanism comprises an ion exchange column and an elution tank in communication, the ion exchange column is in communication with the acidification mechanism and is used for introducing the acidified supernatant, the ion exchange column is used for adsorbing hexavalent chromium ions in the supernatant, and the elution tank is used for introducing alkali elution into the ion exchange column; and the ion exchange column is also in communication with the crystallization mechanism.

[0009] Preferably, the crystallization mechanism comprises a concentration device and a drying device in sequence, the concentration device is in communication with the ion exchange mechanism and is used for introducing the chromium salt solution, the concentration device is used for concentrating the chromium salt solution and introducing it into the drying device for drying to obtain crystalline chromium salt.

[0010] Preferably, it further comprises a post-exchange liquid conditioning mechanism in communication with the ion exchange mechanism, the post-exchange liquid of the ion exchange mechanism is introduced into the post-exchange liquid conditioning mechanism, the post-exchange liquid conditioning mechanism is used for reducing hexavalent chromium in the post-exchange liquid, and the post-exchange liquid can be pressure filtered.

[0011] Preferably, the post-exchange liquid conditioning mechanism comprises a post-exchange liquid conditioning tank, a reducing agent tank and a pressure filtration device in communication, the post-exchange liquid conditioning tank is in communication with the ion exchange mechanism and is used for introducing the post-exchange liquid, the reducing agent tank is used for introducing a reducing agent into the post-exchange liquid conditioning tank, and the post-exchange liquid in the post-exchange liquid conditioning tank can be introduced into the pressure filtration device for pressure filtration, and the clear liquid in the pressure filtration device after pressure filtration can be introduced into an external treatment system.

[0012] Preferably, the post-exchange liquid conditioning tank is also used for introducing a fluorine removal agent to remove fluorine.

[0013] Preferably, the pH value of the lye mixed with the wastewater containing chromium in the impurity removal mechanism is 9.5-10.5.

[0014] Preferably, the pH value of the acid mixed with the supernatant in the acidification mechanism is 2-3.

[0015] The present invention achieves the following technical advantages over the prior art:

[0016] The chromium resource recycling system for hexavalent chromium wastewater provided by this utility model first introduces the chromium-containing wastewater into a purification mechanism. Alkaline solution is added to pre-treat the chromium-containing wastewater through precipitation, removing impurity metal ions such as Cr from the wastewater. 3+ Zn 2 + Cu 2+ Fe 3+ Ni 2+ The resulting supernatant is added to the acidification unit and mixed with acid to adjust the pH to acidity. It then enters the ion exchange unit to adsorb Cr from the supernatant. 6+ And the adsorbed Cr is removed by alkaline elution solution 6+ The solution is regenerated into a chromium salt solution, which is then concentrated and dried using a crystallization mechanism to obtain relatively pure crystalline chromium salt. This process removes impurity metal ions by precipitation beforehand and also improves the chromium content. 6+ Adsorption and desorption are performed to improve the recovery rate of hexavalent chromium. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the chromium resource recycling system in wastewater containing hexavalent chromium provided in Example 1.

[0019] In the diagram: 1-Impurity removal mechanism; 11-Wastewater regulating tank; 12-Sedimentation tank; 13-Alkali tank; 2-Acidification mechanism; 21-Supernatant regulating tank; 22-Acid tank; 3-Ion exchange mechanism; 31-Ion exchange column; 32-Eluent tank; 4-Crystallization mechanism; 41-Concentration device; 42-Drying device; 5-Post-exchange liquid regulating mechanism; 51-Post-exchange liquid regulating tank; 52-Reducing agent tank; 53-Filter press device. Detailed Implementation

[0020] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative efforts fall within the scope of the present application.

[0021] The present application provides a chromium resource recycling system in hexavalent chromium-containing wastewater, to solve the problems in the prior art and improve the recovery content of hexavalent chromium.

[0022] In order to make the above-mentioned purposes, features and advantages of the present application more apparent, obvious and easy to understand, the present application will be further described in detail below with reference to the drawings and specific embodiments.

[0023] Embodiment one

[0024] The present embodiment provides a chromium resource recycling system in hexavalent chromium-containing wastewater, please see Figure 1 , comprising a decontamination mechanism 1, an acidification mechanism 2, an ion exchange mechanism 3 and a crystallization mechanism 4; the decontamination mechanism 1 is used for introducing chromium-containing wastewater and lye, and the chromium-containing wastewater and the lye are mixed in the decontamination mechanism 1 to precipitate impurity metal ions in the chromium-containing wastewater; the acidification mechanism 2 is communicated with the decontamination mechanism 1, the supernatant after mixing of the chromium-containing wastewater and the lye enters the acidification mechanism 2, and the acidification mechanism 2 is also used for introducing acid liquor into the supernatant to adjust the pH of the supernatant; the ion exchange mechanism 3 is communicated with the acidification mechanism 2, and the supernatant after acidification can enter the ion exchange mechanism 3, the ion exchange mechanism 3 can adsorb hexavalent chromium ions in the supernatant, and alkali elution liquor can also be introduced into the ion exchange mechanism 3 to regenerate the adsorbed hexavalent chromium ions into a chromium salt solution; the crystallization mechanism 4 is communicated with the ion exchange mechanism 3, and the chromium salt solution can be introduced into the crystallization mechanism 4, and the crystallization mechanism 4 can concentrate and dry the chromium salt solution to obtain crystalline chromium salt.

[0025] First, the chromium-containing wastewater is introduced into the decontamination mechanism 1, and the chromium-containing wastewater is pretreated by precipitation by adding lye to remove impurity metal ions such as Cr 3+ , Zn 2+ , Cu 2+ , Fe 3+ , Ni 2+ , etc. in the wastewater, and the obtained supernatant is added to the acidification mechanism 2 to mix with acid liquor to become acidic, and then enters the ion exchange mechanism 3 to adsorb Cr 6+ in the supernatant, and the adsorbed Cr 6+The regenerated chromium salt solution is resolved and concentrated by the crystallization mechanism 4, dried and obtained as a relatively pure crystalline chromium salt. In this way, the impurity metal ions are removed by precipitation in advance, and the Cr 6+ content is improved by adsorption resolution.

[0026] In an optional embodiment of the present embodiment, the impurity removal mechanism 1 preferably comprises a wastewater conditioning tank 11, a sedimentation tank 12 and a lye tank 13, the sedimentation tank 12 and the lye tank 13 are both in communication with the wastewater conditioning tank 11, the wastewater conditioning tank 11 is used to introduce chromium-containing wastewater, the lye tank 13 is used to introduce lye into the wastewater conditioning tank 11, the mixed solution in the wastewater conditioning tank 11 is introduced into the sedimentation tank 12, the sedimentation tank 12 is in communication with the acidification mechanism 2, and the supernatant in the sedimentation tank 12 is introduced into the acidification mechanism 2; the chromium-containing wastewater is pumped into the wastewater conditioning tank 11, the lye tank 13 is pumped into the lye to adjust the pH, and then enters the sedimentation tank 12 for solid-liquid separation to remove impurity metal ions such as Cr 3+ , Zn 2+ , Cu 2+ , Fe 3+ , Ni 2+ , etc. in it, and the supernatant enters the acidification mechanism 2 and is precipitated as a comprehensive sludge containing impurity metal ions; wherein the lye is 30% liquid lye, which is used to neutralize and remove impurities in the chromium-containing wastewater, so as to remove the impurity metal cations therein, while the chromate anions are still retained in the aqueous solution.

[0027] Further preferably, the pH value of the lye mixed with the chromium-containing wastewater in the impurity removal mechanism 1 is 9.5-10.5 to fully precipitate the impurity metal ions.

[0028] In an optional embodiment of the present embodiment, the acidification mechanism 2 preferably comprises a supernatant conditioning tank 21 and an acid tank 22, the supernatant conditioning tank 21 is in communication with the impurity removal mechanism 1 and is used to introduce the supernatant, the acid tank 22 is in communication with the supernatant conditioning tank 21 and is used to introduce acid into the supernatant conditioning tank 21; and the supernatant conditioning tank 21 is also in communication with the ion exchange mechanism 3; wherein the acid is 10% sulfuric acid, which is configured in the acid tank 22 and pumped into the supernatant conditioning tank 21 to adjust the pH, and then pumped into the ion exchange mechanism 3, so that the chromate in the solution is converted into dichromate.

[0029] Further preferably, the pH value of the acid mixed with the supernatant in the acidification mechanism 2 is 2-3, preferably 2-2.5.

[0030] In an optional solution of the embodiment, preferably, the ion exchange mechanism 3 comprises a communicating ion exchange column 31 and an eluent tank 32, the ion exchange column 31 is in communication with the acidification mechanism 2 and is used to pass the acidified supernatant, the ion exchange column 31 is used to adsorb the hexavalent chromium ions in the supernatant, and the eluent tank 32 is used to pass the alkali eluent into the ion exchange column 31; the ion exchange column 31 is also in communication with the crystallization mechanism 4; wherein the ion exchange column 31 adopts an anion adsorption exchange column, and forms a matched anion exchange resin system with the eluent tank 32; the acidified supernatant is connected to the inlet of the ion exchange column 31, the outlet of the ion exchange column 31 is connected to the post-exchange liquid adjusting mechanism 5; after the resin in the ion exchange column 31 is saturated, the eluent is used for elution and regeneration, specifically: the eluent tank 32 is configured with an eluent with a suitable concentration, which is pumped into the ion exchange column 31 for adsorption, and the eluent flowing out of the outlet is introduced into the crystallization mechanism 4; wherein the eluent adopts 30% liquid alkali, and the chromium salt solution is sodium chromate solution.

[0031] In an optional solution of the embodiment, preferably, the crystallization mechanism 4 comprises a concentration device 41 and a drying device 42 in sequence communication, the concentration device 41 is in communication with the ion exchange mechanism 3 and is used to pass the chromium salt solution, the concentration device 41 is used to concentrate the chromium salt solution and pass it into the drying device 42 to obtain the crystallized chromium salt after drying; wherein the concentration device 41 adopts an evaporation concentration device, when the chromium salt solution obtained by elution is concentrated in the evaporation concentration device to a large amount of crystalline salt, the condensate generated by evaporation concentration can be returned to the ion exchange 3, and the crystalline salt is sent to the drying device 42 for drying to obtain sodium chromate salt products such as drum drying or spray drying; sodium chromate is soluble in water and methanol, slightly soluble in ethanol, has oxidizing property, can be reduced to trivalent chromium, and can be used for dye and pigment preparation.

[0032] In an optional solution of the embodiment, preferably, the chromium resource recycling system in the hexavalent chromium-containing wastewater provided in the embodiment further comprises a post-exchange liquid adjusting mechanism 5 in communication with the ion exchange mechanism 3, the post-exchange liquid of the ion exchange mechanism 3 is used to pass into the post-exchange liquid adjusting mechanism 5, and the post-exchange liquid adjusting mechanism 5 is used to reduce the remaining hexavalent chromium in the post-exchange liquid into trivalent chromium, facilitating the removal of chromium.

[0033] In an optional solution of the embodiment, preferably, the post-exchange liquid adjusting mechanism 5 comprises a communicating post-exchange liquid adjusting tank 51, a reducing agent tank 52 and a pressure filtration device 53, the post-exchange liquid adjusting tank 51 is communicated with the ion exchange mechanism 3 and used for feeding the post-exchange liquid, the reducing agent tank 52 is used for pumping the reducing agent into the post-exchange liquid adjusting tank 51, the post-exchange liquid in the post-exchange liquid adjusting tank 51 can be pumped into the pressure filtration device 53 for pressure filtration, the clear liquid in the pressure filtration device 53 after pressure filtration can be fed into an external treatment system, wherein the pressure filtration device 53 adopts a plate-and-frame filter press, the reducing agent adopts 10% sodium pyrosulfite, the hexavalent chromium is reduced, the pH is adjusted, and the chromium mud is obtained by pressure filtration through the pressure filtration device 53, so as to be recycled subsequently, and the clear liquid after pressure filtration enters the external treatment system such as an SCR system for subsequent treatment.

[0034] In an optional solution of the embodiment, preferably, the post-exchange liquid adjusting tank 51 is also used for feeding a fluorine removal agent for fluorine removal; specifically, a fluorine removal pool can be arranged after the post-exchange liquid adjusting tank 51 for fluorine removal, so as to reduce the corrosion of fluorine on the SCR system.

[0035] Further preferably, the stirring devices can be arranged in the tanks of the chromium resource recycling system in the hexavalent chromium-containing wastewater according to the needs, so as to improve the treatment efficiency.

[0036] The principle and implementation mode of the specific examples are used to illustrate the principle and implementation mode of the utility model, and the above embodiment is only used to help understand the method and core idea of the utility model; meanwhile, for the general technical personnel in the field, the specific implementation mode and application range will be changed according to the idea of the utility model. In conclusion, the content of the specification should not be understood as the limitation of the utility model.

Claims

1. A system for recycling chromium resources in wastewater containing hexavalent chromium, characterized in that it comprises: The application relates to a chromium-containing waste water treatment device. The device comprises: a removing impurity mechanism (1) for feeding in chromium-containing waste water and lye, wherein the chromium-containing waste water and the lye are mixed in the removing impurity mechanism (1) to precipitate impurity metal ions in the chromium-containing waste water; an acidification mechanism (2) in communication with the removing impurity mechanism (1), wherein supernatant after the mixing of the chromium-containing waste water and the lye is fed into the acidification mechanism (2), and the acidification mechanism (2) is also used for feeding in acid liquor into the supernatant to adjust the pH of the supernatant; an ion exchange mechanism (3) in communication with the acidification mechanism (2), wherein the supernatant after the acidification can be fed into the ion exchange mechanism (3), the ion exchange mechanism (3) can adsorb hexavalent chromium ions in the supernatant, and the ion exchange mechanism (3) can also feed in lye for desorption to regenerate the adsorbed hexavalent chromium ions into a chromium salt solution; and 2. The system for recycling chromium resources in wastewater containing hexavalent chromium according to claim 1, characterized in that: a crystallization mechanism (4) in communication with the ion exchange mechanism (3), wherein the chromium salt solution can be fed into the crystallization mechanism (4), and the crystallization mechanism (4) can concentrate and dry the chromium salt solution to obtain crystalline chromium salt.

3. The system for recycling chromium resources in wastewater containing hexavalent chromium according to claim 1, characterized in that: The removing impurity mechanism (1) comprises a waste water adjusting tank (11), a precipitation tank (12) and a lye tank (13), the precipitation tank (12) and the lye tank (13) are in communication with the waste water adjusting tank (11), the waste water adjusting tank (11) is used for feeding in chromium-containing waste water, the lye tank (13) is used for feeding in lye into the waste water adjusting tank (11), the mixed liquid in the waste water adjusting tank (11) is fed into the precipitation tank (12), the precipitation tank (12) is in communication with the acidification mechanism (2), and the supernatant in the precipitation tank (12) is fed into the acidification mechanism (2).

4. The system for recycling chromium resources in wastewater containing hexavalent chromium according to claim 1, characterized in that: The acidification mechanism (2) comprises a supernatant adjusting tank (21) and an acid liquor tank (22), the supernatant adjusting tank (21) is in communication with the removing impurity mechanism (1) and is used for feeding in supernatant, the acid liquor tank (22) is in communication with the supernatant adjusting tank (21) and is used for feeding in acid liquor into the supernatant adjusting tank (21), and the supernatant adjusting tank (21) is also in communication with the ion exchange mechanism (3).

5. The system for recycling chromium resources from wastewater containing hexavalent chromium according to claim 1, characterized in that: The ion exchange mechanism (3) comprises an ion exchange column (31) and a desorption liquid tank (32) in communication, the ion exchange column (31) is in communication with the acidification mechanism (2) and is used for feeding in supernatant after the acidification, the ion exchange column (31) is used for adsorbing hexavalent chromium ions in the supernatant, and the desorption liquid tank (32) is used for feeding in lye for desorption into the ion exchange column (31); and the ion exchange column (31) is also in communication with the crystallization mechanism (4). The crystallization mechanism (4) comprises a concentration device (41) and a drying device (42) in sequence, the concentration device (41) is in communication with the ion exchange mechanism (3) and is used for feeding in a chromium salt solution, the concentration device (41) is used for concentrating the chromium salt solution and feeding into the drying device (42) to dry to obtain crystalline chromium salt.

6. The system for recycling chromium resources from wastewater containing hexavalent chromium according to claim 1, characterized in that: The post-ion exchange liquid adjusting mechanism (5) is communicated with the ion exchange mechanism (3), the post-ion exchange liquid of the ion exchange mechanism (3) is used to enter the post-ion exchange liquid adjusting mechanism (5), the post-ion exchange liquid adjusting mechanism (5) is used to reduce the hexavalent chromium in the post-ion exchange liquid, and the post-ion exchange liquid can be pressure filtered.

7. The system for recycling chromium resources from wastewater containing hexavalent chromium according to claim 6, characterized in that: The post-ion exchange liquid adjusting mechanism (5) comprises a post-ion exchange liquid adjusting tank (51), a reducing agent tank (52) and a pressure filtration device (53), the post-ion exchange liquid adjusting tank (51) is communicated with the ion exchange mechanism (3) and used to enter the post-ion exchange liquid, the reducing agent tank (52) is used to enter the reducing agent into the post-ion exchange liquid adjusting tank (51), and the post-ion exchange liquid in the post-ion exchange liquid adjusting tank (51) can enter the pressure filtration device (53) to be pressure filtered, and the clear liquid in the pressure filtration device (53) after pressure filtration can enter an external treatment system.

8. The system for recycling chromium resources from wastewater containing hexavalent chromium according to claim 7, characterized in that: The post-ion exchange liquid adjusting tank (51) is also used to enter a fluorine removal agent to remove fluorine.

9. The system for recycling chromium resources from wastewater containing hexavalent chromium according to claim 1, characterized in that: The pH value of the lye mixed with the chromium-containing wastewater in the impurity removal mechanism (1) is 9.5-10.

5.

10. The system for recycling chromium resources from wastewater containing hexavalent chromium according to claim 1, characterized in that: The pH value of the acid liquid mixed with the supernatant in the acidification mechanism (2) is 2-3.

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