CN111875146A - Resource utilization system and method for tin-stripping wastewater - Google Patents
Resource utilization system and method for tin-stripping wastewater Download PDFInfo
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- CN111875146A CN111875146A CN202010797848.7A CN202010797848A CN111875146A CN 111875146 A CN111875146 A CN 111875146A CN 202010797848 A CN202010797848 A CN 202010797848A CN 111875146 A CN111875146 A CN 111875146A
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Abstract
The invention discloses a tin-stripping wastewater resource utilization system and method, relates to the technical field of wastewater resource utilization, and aims to recover valuable sodium nitrate with higher purity from tin-stripping wastewater under the condition of reducing cost, so that the tin-stripping wastewater is utilized as a resource. The system comprises a first processing unit, a second processing unit, a desulfurization unit, an evaporation unit and a deamination unit; the desulfurizer used by the desulfurization unit is calcium aluminate; the water inlet of the first processing unit is respectively communicated with a tin-stripping wastewater supply pipeline and an alkali liquor supply pipeline, the water outlet of the first processing unit and the alkali liquor supply pipeline are both communicated with the water inlet of the second processing unit, the water outlet of the second processing unit is communicated with the water inlet of the desulfurization unit, the water outlet of the desulfurization unit is communicated with the water inlet of the evaporation unit, the condensate outlet of the evaporation unit is communicated with the water inlet of the deamination unit, and the outlet of the deamination unit is communicated with an outer discharge pipeline. The method is applied to the system.
Description
Technical Field
The invention relates to the technical field of waste water recycling, in particular to a tin-stripping waste water recycling system and method.
Background
In the manufacturing process of the circuit board, the tin/lead-tin alloy layer on the surface of copper is usually removed by using a tin removing liquid so as to ensure that the surface of copper is bright as new, but a large amount of tin removing waste water is generated, so that the environmental pollution is great, and therefore, the tin removing waste water needs to be subjected to resource treatment.
At present, ammonia water can be adopted to treat tin-stripping wastewater, so that tin contained in the tin-stripping wastewater is precipitated, copper is recovered by adopting an ion exchange adsorption mode, and ammonium nitrate wastewater is generated. After that, ammonia nitrogen removal treatment may be performed on the ammonium nitrate wastewater by using a deamination tower, and after the pH of the effluent is adjusted, outsourcing treatment may be performed as a nutrient solution. However, although this method can remove heavy metal ions such as copper and tin contained in the tin stripping wastewater, after the pH adjustment in the later stage, ammonia nitrogen removal treatment can be performed on the ammonium nitrate wastewater by using a deamination tower, and after the pH of the effluent is adjusted, the effluent is sent into an evaporator for crystallization to obtain a sodium nitrate product. However, the sodium nitrate product obtained by the method has low purity and serious resource waste.
Disclosure of Invention
The invention aims to provide a tin-stripping wastewater resource utilization system and method, which are used for recovering high-purity valuable sodium nitrate from tin-stripping wastewater under the condition of reducing cost, so that the tin-stripping wastewater is utilized as a resource.
In order to achieve the aim, the invention provides a tin-stripping wastewater resource utilization system, which comprises a first treatment unit, a second treatment unit, a desulfurization unit, an evaporation unit and a deamination unit; the desulfurizer used by the desulfurization unit is calcium aluminate;
the water inlet of the first processing unit is respectively communicated with a tin-stripping wastewater supply pipeline and an alkali liquor supply pipeline for supplying a sodium hydroxide solution, the water outlet of the first processing unit and the alkali liquor supply pipeline are both communicated with the water inlet of the second processing unit, the water outlet of the second processing unit is communicated with the water inlet of the desulfurization unit, the water outlet of the desulfurization unit is communicated with the water inlet of the evaporation unit, the condensate outlet of the evaporation unit is communicated with the water inlet of the deamination unit, and the outlet of the deamination unit is communicated with an outer discharge pipeline.
Compared with the prior art, in the tin-stripping wastewater resource utilization system provided by the invention, the water inlet of the first treatment unit is respectively communicated with the tin-stripping wastewater supply pipeline and the alkali liquor supply pipeline for supplying sodium hydroxide solution, the water outlet of the first treatment unit and the alkali liquor supply pipeline are both communicated with the water inlet of the second treatment unit, and the water outlet of the second treatment unit is communicated with the water inlet of the desulfurization unit. Based on this, after the first treatment unit utilizes the sodium hydroxide solution to carry out the tin precipitation treatment on the tin-stripping wastewater, the second treatment unit can continue to utilize the sodium hydroxide solution to carry out the neutralization treatment on the supernatant of the waste tin water so as to primarily remove copper ions contained in the supernatant of the waste tin water, and utilizes sodium sulfide to carry out the copper removal treatment on the obtained pretreatment liquid. Moreover, the desulfurizer used by the desulfurization unit is calcium aluminate, and calcium chlorate can remove sulfate ions and chloride ions contained in the sodium nitrate wastewater. In addition, because the sodium hydroxide solution is used for neutralizing the clear liquid of the waste tin water, the pH value of the sodium nitrate wastewater sent out from the desulfurization unit is alkalescent, and the sodium nitrate wastewater can directly enter the evaporation unit for evaporation under the condition that the pH value of the sodium nitrate wastewater is not regulated by hydrochloric acid, so that the sodium nitrate with higher purity can be crystallized. In this case, the problem of chloride ion contamination due to copper removal by ion exchange and pH adjustment can be avoided, the process steps can be simplified, and the yield and purity of sodium nitrate can be improved. Proved by experiments, the ion exchange copper removal is modified into alkali liquor copper removal and sodium sulfide copper removal in the early stage, so that the pH value of the sodium nitrate wastewater is not required to be adjusted by hydrochloric acid, and the sulfate radical and chloride ions are removed by calcium chlorate, so that the chloride ions are reduced to be below 2wt%, the sulfate radical content is reduced to be below 3%, and the main content of the sodium nitrate is increased to 90 wt%. And 54t of liquid caustic soda (relative to ammonia water) can be saved every month according to the treatment capacity of 1000 tons of tin stripping water every month. And because the condensate outlet of the evaporation unit is communicated with the water inlet of the deamination unit, and the outlet of the deamination unit is communicated with an external discharge pipeline, the ammonia nitrogen content in the condensate water is lower than 5ppm and the copper content is lower than 0.5ppm after the ammonia nitrogen enriched in the condensate water is removed by the deamination unit, so that after the deamination treatment is carried out on the condensate water, the discharge liquid reaching the standard can be discharged through the external discharge pipeline, and the environment is hardly polluted.
Therefore, the tin-stripping wastewater resource utilization system provided by the invention can simplify the tin-stripping wastewater resource utilization process by only changing part of pipelines under the condition of not increasing the equipment budget, so as to improve the yield of sodium sulfate and reduce the environmental pollution.
The invention also provides a resource utilization method of the tin stripping wastewater, which is characterized by comprising the following steps:
the embodiment of the invention also provides a resource utilization method of the tin-stripping wastewater, which comprises the following steps:
and (3) carrying out tin precipitation and flocculation treatment on the tin-stripping wastewater by using a sodium hydroxide solution to obtain tin-containing slurry and a clear liquid of waste tin water.
And (3) neutralizing the clear liquid of the waste tin water by using a sodium hydroxide solution to remove copper ions contained in the clear liquid of the waste tin water for the first time to obtain a pretreatment solution.
And carrying out copper removal treatment on the pretreatment liquid by using sodium sulfide to obtain sodium nitrate wastewater.
And removing sulfate radicals and chloride ions contained in the sodium nitrate wastewater by using calcium chloride.
Distilling the sodium nitrate wastewater to recover sodium nitrate contained in the sodium nitrate wastewater and condensed water generated by distillation.
And (4) performing deamination treatment on the condensed water, and discharging deaminated effluent.
Compared with the prior art, the tin-stripping wastewater resource utilization method provided by the invention has the same beneficial effects as the tin-stripping wastewater resource utilization system in the technical scheme, and the details are not repeated herein.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention and not to limit the invention. In the drawings:
fig. 1 is a first schematic structural diagram of a tin stripping wastewater resource utilization system provided by an embodiment of the invention;
FIG. 2 is a schematic structural diagram II of a tin stripping wastewater resource utilization system provided by the embodiment of the invention;
fig. 3 is a flowchart of a resource utilization method of tin-stripping wastewater provided by the embodiment of the invention.
Detailed Description
In order to make the technical problems, technical solutions and advantageous effects to be solved by the present invention more clearly apparent, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
It will be understood that when an element is referred to as being "secured to" or "disposed on" another element, it can be directly on the other element or be indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or be indirectly connected to the other element.
Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise. The meaning of "a number" is one or more unless specifically limited otherwise.
In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; either directly or indirectly through intervening media, either internally or in any other suitable relationship. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.
In the process of manufacturing the circuit board, the tin stripping liquid is often used for stripping the tin layer on the copper surface so as to make the copper surface bright as new, but a large amount of tin stripping waste water is generated. The common tin stripping liquid is nitric acid type tin stripping liquid, and after the tin layer on the surface of copper is removed by the nitric acid type tin stripping liquid, the generated tin stripping waste water needs to be treated, for example: a proper amount of sulfuric acid can be added into the tin stripping wastewater, then ammonia water is added to adjust the pH value to be within the range of 1.5-2.0, and 1/1000 polyacrylamide flocculant is added through a delivery pump for flocculation and precipitation until an obvious flocculation effect is achieved. And (3) filtering by using a plate-and-frame filter press, then enabling the filtrate to enter a wastewater treatment workshop, and recovering copper by adopting an ion exchange adsorption mode to generate ammonium nitrate wastewater. And then, ammonia nitrogen removal treatment can be carried out on the ammonium nitrate wastewater by adopting a deamination tower, and after the pH value of effluent is adjusted, the effluent is sent into an evaporator for crystallization to obtain a sodium nitrate product. The inventor tests various data of sodium nitrate products, and the test results are shown in table 1.
TABLE 1 data of the prior art sodium nitrate products
| Batches of | Water content/wt% | Sodium/wt.% | Nitrate radical/wt% | Chloride ion/wt% | Sulfate radical/wt% | Copper/wt% | Sodium nitrate/wt% |
| First batch | 3.5 | 27.3 | 52.4 | 14.06 | 4.41 | 0.0029 | 71.84 |
| Second batch | 4.25 | 27 | 52.14 | 13.87 | 3.7 | 0.0026 | 71.48 |
| Third batch | 3.35 | 27.64 | 51.71 | 14.18 | 4.75 | 0.0037 | 70.89 |
As can be seen from Table 1, the sodium nitrate content is 70-80 wt%, and the sodium nitrate contains a large amount of chloride and sulfate. The reason for the higher chloride content is the following:
a. the tin wastewater enters ion exchange resin for deep copper removal, and part of chloride ions are carried into the wastewater system. b. When the pH value of the water discharged from the deamination tower is too high (> 12), hydrochloric acid is required to be added to adjust the pH value to 8.5-9.5, and partial chloride ions are also brought into the system in the step. c. The tin stripping waste liquid contains 1% -2% of chloride ions.
As shown in fig. 1, the resource utilization system for tin-stripping wastewater provided by the embodiment of the invention comprises: a first processing unit 100, a second processing unit 200, an evaporation unit 400, and a deamination unit 500. The water inlet of the first processing unit 100 is respectively communicated with a tin-stripping wastewater supply pipeline b and an alkali liquor supply pipeline a for supplying sodium hydroxide solution. The water outlet of the first processing unit 100 and the alkali liquor supply pipeline a are both communicated with the water inlet of the second processing unit 200. The water outlet of the second treating unit 200 is communicated with the water inlet of the desulfurizing unit 300. The water outlet of the desulfurization unit 300 is communicated with the water inlet of the evaporation unit 400. The condensate outlet of the evaporation unit 400 is communicated with the water inlet of the deamination unit 500. The outlet of the deamination unit 500 is communicated with an external discharge pipeline.
In specific implementation, the tin-stripping wastewater is supplied to the first treatment unit 100 by the tin-stripping wastewater supply pipeline b, and the sodium hydroxide solution (50 wt%) is supplied to the first treatment unit 100 by the alkali liquor supply pipeline a, so that the tin-stripping wastewater and the sodium hydroxide solution react in the first treatment unit 100, the tin-stripping supernatant is separated from the tin-stripping wastewater, and the precipitate is led out in the form of tin-containing sludge. The first processing unit 100 sends the separated tin-stripping supernatant liquid to the second processing unit 200, and the second processing unit 200 receives the sodium hydroxide solution provided by the alkali liquor supply pipeline a and performs neutralization treatment on the tin-stripping supernatant liquid. In the neutralization process, copper ions contained in the tin stripping supernatant are gradually separated out, and then a crude copper hydroxide product and a primary treatment solution are obtained. And then, carrying out copper removal treatment on the pretreatment liquid by using sodium sulfide to obtain sodium nitrate wastewater. Since the second treatment unit 200 performs neutralization treatment on the tin-stripping supernatant by using a sodium hydroxide solution, after the second treatment unit 200 performs copper removal treatment on the pretreatment solution by using sodium sulfide, the pH value of the obtained sodium nitrate wastewater is weakly alkaline.
On the basis, the sodium nitrate wastewater is treated by using calcium chlorate to reduce sulfate ions and chloride ions in the sodium nitrate wastewater. In this process, calcium aluminate can chemically react with sulfate ions to produce water-insoluble needle-like crystals of calcium sulfoaluminate (3 CaO · Al2O3 · 3CaSO4 · 31H 2O). The calcium aluminate powder and the modified substances thereof have certain dechlorination effect, so that the calcium aluminate can be used for removing sodium nitrate sulfate radicals and chloride ions so as to improve the purity of the sodium nitrate product. And the needle-shaped calcium sulphoaluminate crystals can be separated from water by adopting flexible and various solid-liquid separation technologies. Table 2 shows the physicochemical indices of calcium aluminate.
The inventor researches on the mechanism of removing sulfate radicals by calcium aluminate and finds that sulfate ions in sodium nitrate wastewater and Ca hydrolyzed from calcium aluminate2+CaSO4 may be formed. In addition, because the pH value of the sodium nitrate wastewater is alkalescent, the Ca can be made to be Ca by adding the calcium chlorate into the sodium nitrate wastewater2+And Al3+In the presence of an alkaline environment, Ca2+And Al3+Can combine with sulfate radicals to react to generate ettringite precipitate, thereby ensuring that the mass concentration of the sulfate radicals in the sodium nitrate wastewater can be reduced to 200ppm at least. Wherein the ettringite is formed from [ Al (OH)6]3-Octahedron, aluminum octahedron and calcium polyhedron are alternately arranged to form a multi-face column and SO42-Entering the groove between the columns to balance positive charges and connecting in series. The chemical reaction for forming ettringite can be divided into three processes, which are respectively:
Al(OH)4-+ 2OH-→[Al(OH)6]3-
[Al(OH)6]3-+ Ca2++ H2O →[Ca3Al(OH)6·12H2O]3-
[Ca3Al(OH)6·12H2O]3-+SO42-+ H2O→Ca6Al2(SO4)3(OH)12·26H2O
due to the specific chemical structure and low solubility product of the ettringite, the ettringite precipitation method is used for treating the sulfate wastewater and can effectively remove sulfate ions.
In addition, as shown in fig. 1, since the pH of the sodium nitrate wastewater is weakly alkaline, the desulfurization unit 300 may directly introduce the sodium nitrate wastewater into the evaporation unit 400 for crystallization treatment without adjusting the pH of the sodium nitrate wastewater. The condensate of the evaporation unit 400 is enriched with certain ammonia nitrogen during the crystallization process, so that the condensate can be deaminated by the deamination unit 500.
As shown in fig. 1, based on the above specific implementation process, the water inlet of the first processing unit 100 is respectively communicated with the tin-stripping wastewater supply pipeline b and the alkali liquor supply pipeline a for supplying sodium hydroxide solution, the water outlet of the first processing unit 100 and the alkali liquor supply pipeline a are both communicated with the water inlet of the second processing unit 200, and the water outlet of the second processing unit 200 is communicated with the water inlet of the desulfurization unit 300. Based on this, after the first treatment unit 100 performs tin precipitation treatment on the tin-stripping wastewater by using the sodium hydroxide solution, the second treatment unit 200 may continue to perform neutralization treatment on the supernatant of the waste tin water by using the sodium hydroxide solution to primarily remove copper ions contained in the supernatant of the waste tin water, and perform copper removal treatment on the obtained pretreatment liquid by using sodium sulfide. Moreover, the desulfurizer used in the desulfurization unit 300 is calcium aluminate, and calcium chlorate can remove sulfate ions and chloride ions contained in the sodium nitrate wastewater. In addition, since the sodium hydroxide solution is used to neutralize the supernatant of the waste tin water, the pH of the sodium nitrate wastewater discharged from the desulfurization unit 300 is weakly alkaline, and the sodium nitrate wastewater can directly enter the evaporation unit 400 to be evaporated without adjusting the pH of the sodium nitrate wastewater by hydrochloric acid, so that the sodium nitrate with high purity can be crystallized. In this case, the problem of chloride ion contamination due to copper removal by ion exchange and pH adjustment can be avoided, the process steps can be simplified, and the yield and purity of sodium nitrate can be improved. Proved by experiments, the ion exchange copper removal is modified into alkali liquor copper removal and sodium sulfide copper removal in the early stage, so that the pH value of the sodium nitrate wastewater is not required to be adjusted by hydrochloric acid, and the sulfate radical and chloride ions are removed by calcium chlorate, so that the chloride ions are reduced to be below 2wt%, the sulfate radical content is reduced to be below 3%, and the main content of the sodium nitrate is increased to 90 wt%. And 54t of liquid caustic soda (relative to ammonia water) can be saved every month according to the treatment capacity of 1000 tons of tin stripping water every month. And because the condensate outlet of the evaporation unit 400 is communicated with the water inlet of the deamination unit 500, and the outlet of the deamination unit 500 is communicated with an external discharge pipeline, after ammonia nitrogen enriched in condensate is removed by the deamination unit 500, the content of ammonia nitrogen contained in the condensate is lower than 5ppm, and the content of copper is lower than 0.5ppm, so that after the deamination treatment is performed on the condensate, the condensate can be discharged through the external discharge pipeline to reach the standard, and the environment is hardly polluted.
Therefore, the tin-stripping wastewater resource utilization system provided by the invention can simplify the tin-stripping wastewater resource utilization process by only changing part of pipelines under the condition of not increasing the equipment budget, so as to improve the yield of sodium sulfate and reduce the environmental pollution.
In some embodiments, as shown in fig. 2, the first processing unit 100 may include: a tin precipitation tank 101, a first flocculation tank 102 and a first sedimentation tank 103. The water inlet of the tin precipitation tank 101 is communicated with an alkali liquor supply pipeline a and a tin stripping wastewater supply pipeline b. The water outlet of the tin precipitation tank 101 is communicated with the water inlet of the first flocculation tank 102, and the water outlet of the first flocculation tank 102 is communicated with the water inlet of the first sedimentation tank 103.
In specific implementation, the alkali liquor supply pipeline a supplies sodium hydroxide solution to the tin depositing pool 101, and the tin stripping wastewater supply pipeline b supplies tin stripping wastewater to the tin depositing pool 101, so that the sodium hydroxide solution and the tin stripping wastewater react in the tin depositing pool 101 to form tin-containing precipitate. In order to remove tin-containing sediment, tin-stripping wastewater containing the tin-containing sediment is sent to a first flocculation tank 102, flocculating agents such as polyacrylamide PAM and sodium polyacrylate are added into the first flocculation tank 102, then the first flocculation tank 103 is sent to form tin-containing slurry and waste tin water supernatant, and the tin-containing slurry is discharged and compressed to form tin sludge. The tin sludge can be further purified to recover the tin contained therein. In the process, flocculating agents such as acrylamide (PAM), sodium polyacrylate and the like can also reduce COD of the supernatant of the waste tin water.
In some embodiments, as shown in fig. 2, the second processing unit 200 includes: a primary copper removal bath 201 and a secondary copper removal bath 202. The water inlet of the primary decoppering tank 201 is respectively communicated with the water outlet of the first treatment unit 100 and the alkali liquor supply pipeline a. The water outlet of the primary copper removing pool 201 is communicated with the water inlet of the secondary copper removing pool 202. The water outlet of the secondary decoppering tank 202 is communicated with the water inlet of the evaporation unit 400.
As shown in fig. 2, when the first treatment unit 100 includes the tin precipitation tank 101, the first flocculation tank 102, and the first sedimentation tank 103, the water inlet of the primary copper removal tank 201 is communicated with the water outlet of the first sedimentation tank 103. When the tin-stripping wastewater resource utilization system further comprises a second flocculation tank 601 and a second sedimentation tank 602, the water outlet of the secondary copper removal tank 202 is communicated with the water inlet of the second flocculation tank 601.
In specific implementation, the alkali solution supply pipeline a feeds a sodium hydroxide solution into the primary copper removal tank 201, and the first processing unit 100 provides the supernatant of the waste tin water to the primary copper removal tank 201. In the primary copper removing tank 201, the sodium hydroxide solution neutralizes the supernatant of the waste tin water, so that the pH value of the supernatant of the waste tin water is close to neutral, and simultaneously, the supernatant of the waste tin water reacts with copper ions contained in the supernatant of the precipitated tin to form a crude copper hydroxide product and a pretreatment solution. In addition, in the primary copper removing tank 201, the copper ions contained in the waste tin water supernatant are removed by neutralizing the waste tin water supernatant with a sodium hydroxide solution, so that impurity ions, such as chloride ions, introduced by copper removal by an ion exchange method can be avoided. And the secondary copper removing tank 202 uses sodium sulfide to remove copper ions contained in the pretreatment liquid, so that introduction of sulfate radicals is reduced, and unnecessary introduction of impurities is avoided.
In addition, as shown in fig. 2, the primary copper removal tank 201 separates the crude copper hydroxide and the pretreatment liquid, sends the pretreatment liquid to the secondary copper removal tank 202, and adds sodium sulfide into the secondary copper removal tank 202, so that the sodium sulfide reacts with copper ions to form sodium nitrate wastewater containing copper sulfide. Because the clear liquid of the waste tin water is neutralized in the sodium hydroxide solution of the primary copper removing tank 201, the sodium nitrate wastewater is close to neutral, hydrochloric acid is not required to be added to adjust the pH value of the sodium nitrate wastewater, and the secondary copper removing tank 202 can be directly introduced into the evaporation unit 400 for crystallization after copper sulfide precipitate contained in the sodium nitrate wastewater is removed, so that the yield of the sodium nitrate is improved. In addition, sodium ions contained in the sodium sulfide and sodium ions contained in the sodium hydroxide remain in the obtained sodium nitrate wastewater, so that the content of the sodium ions contained in the sodium nitrate wastewater is increased, and the yield of the sodium nitrate generated by the evaporation in the subsequent evaporation unit 400 can be further improved.
In some embodiments, as shown in fig. 2, the above-mentioned desulfurization unit 300 may include: a desulfurization tank 301 and a third settling tank 302. The water outlet of the second sedimentation tank 602 is communicated with the water inlet of the desulfurization tank 301. The water outlet of the desulfurization tank 301 is communicated with the water inlet of the third sedimentation tank 302. The water outlet of the third sedimentation tank 302 is communicated with the water inlet of the evaporation unit 400. When the tin-stripping wastewater resource utilization system further comprises a second flocculation tank 601 and a second sedimentation tank 602, the water inlet of the second sedimentation tank 602 is communicated with the water inlet of the second sedimentation tank 602. The water outlet of the secondary decoppering tank 202 is communicated with the water inlet of the evaporation unit 400.
In specific implementation, as shown in fig. 2, calcium chlorate may be put into the desulfurization tank 301 to react with ammonium nitrate wastewater to generate ettringite precipitate, and the third sedimentation tank 302 is used to separate the ettringite precipitate from the sodium nitrate wastewater, so that the third sedimentation tank 302 sends the sodium nitrate wastewater to the evaporation unit 400.
To demonstrate the effectiveness of the protocol, Table 3 illustrates a data monitoring table for waste tin wastewater from a certain manufacturer.
Table 3 data monitoring table for waste tin waste water
| Cu(ppm) | pH | Ammonia nitrogen (ppm) | Cu（ppm） | Sulfate radical/wt% | Nitrate radical/wt% | Tin (ppm) |
| 8556.34 | ＜1 | 3508.36 | 4034.28 | 12.51% | 20.28% | 5201.25 |
As shown in fig. 2, when the tin-stripping wastewater shown in table 3 is treated, the pH of the tin-stripping wastewater is adjusted to 1.5-2 by using 50wt% of sodium hydroxide solution in the tin-depositing tank 101, so that tin ions in the tin-stripping wastewater are deposited; then 20g of PAM is added into the first flocculation tank 102 according to each liter of tin-stripping waste water to carry out flocculation treatment on the tin-stripping waste water. Then, the first sedimentation tank 103 is used for extracting the supernatant of the waste tin water. Adding 50wt% of sodium hydroxide solution into the primary copper removing tank 201 until the pH value of the supernatant of the waste tin water is neutral; and then, treating the pretreatment liquid by using sodium sulfide in a secondary copper removal tank 202 in a manner that 10g of sodium sulfide is added into each liter of the pretreatment liquid to obtain sodium nitrate wastewater, wherein the monitoring data of the sodium nitrate wastewater is shown in Table 4.
Table 4 data monitoring table of waste tin water supernatant and sodium nitrate wastewater
As can be seen from Table 4, the pH value of the waste tin water supernatant is 1.59-1.75, the pH value of the obtained pretreatment solution is close to neutral after one copper removal treatment, and neutral or alkaline sodium nitrate wastewater can be obtained after sodium sulfide treatment. Meanwhile, by comparing the copper content, the copper content of the waste tin water supernatant is 6500-8500 ppm, and the copper content of the pretreatment liquid is reduced to 50-60 ppm after one-time copper removal treatment; after the secondary copper removal treatment, the copper content of the sodium nitrate wastewater can be reduced to below 10ppm, and the discharge requirement is met.
Next, as shown in fig. 2, the sodium nitrate wastewater is treated in such a manner that 20g of PAM is added per liter of sodium nitrate wastewater in the second flocculation tank 601, and then precipitated in the second precipitation tank 602, thereby separating the sodium nitrate wastewater. To demonstrate the sulfate and chloride ion reduction of the sodium nitrate wastewater system, table 5 illustrates 2 batches of data for sodium nitrate wastewater.
TABLE 5 data sheet for sodium nitrate wastewater before two batches of treatments
Adding 15g of calcium aluminate into each liter of sodium nitrate wastewater, adding the calcium aluminate into two batches of sodium nitrate wastewater shown in table 4 to remove impurities, wherein the data of the sodium nitrate wastewater after the impurities are removed is shown in table 6.
TABLE 6 data sheet of sodium nitrate wastewater after two batches of treatments
As can be seen from tables 5 and 6, the sulfate content in the sodium nitrate wastewater is reduced by about 90%, the chloride ion content is reduced by about 25%, and the reduction effect is very obvious.
As shown in fig. 2, the evaporation unit 400 may be a triple-effect evaporator 401. When the triple-effect evaporator 401 adopts negative pressure evaporation, if the internal pressure of the triple-effect evaporator 401 is increased (positive pressure), under a controllable condition, a steam valve of the triple-effect evaporator 401 is closed firstly, then a water spraying pneumatic valve at the top of a separator of the triple-effect evaporator 401 is opened, fast forwarding and discharging are added, and the internal temperature of the system is reduced. Table 7 also illustrates various data for the sodium nitrate product crystallized from the triple effect evaporator 401.
TABLE 7 data for sodium nitrate product crystallized from triple effect evaporator
| Water content/wt% | Chloride ion/wt% | Sulfate radical/wt% | Nitrate radical/wt% | Sodium nitrate/wt% |
| 3.56 | 1.64 | 0.70 | 66.28 | 90.87% |
| 3.21 | 1.51 | 0.62 | 66.46 | 91.11% |
Comparing table 1 and table 7, it can be seen that: the resource utilization system for the tin stripping wastewater provided by the embodiment of the invention can effectively ensure that the purity of the obtained ammonium nitrate product reaches over 90wt%, and ensure that the concentration of chloride ions and sulfate ions in the ammonium nitrate product is lower than 2 wt%.
Optionally, as shown in fig. 2, the deamination unit 500 is a stripping deamination unit 500, an ion exchange deamination unit 500 or a bleaching deamination unit 500. For example, when the deamination unit is a stripping deamination unit, the deamination unit can be a deamination tower 501. At the moment, the processing capacity of the triple-effect evaporator 401 can reach 6 t/h-8 t/h, and the processing capacity of the deamination tower 501 can reach 4 t-5 t.
To demonstrate the effectiveness of the protocol, the inventors monitored the effluent during the treatment of triple effect evaporator 401 and deamination tower 501, and the results are shown in tables 8 and 9.
TABLE 8 data monitoring table for triple effect evaporator
TABLE 9 waste liquid treatment data sheet of deamination tower
In order to reflect the data of the deamination effluent more accurately, the deamination effluent is measured for a plurality of times, averaged and compared with the index of the standard water to obtain a data comparison table of the deamination effluent and the standard water as shown in the table 10.
TABLE 10 data comparison of deamination water and standard water
| Name (R) | pH | Ammonia nitrogen/ppm | Cu/ppm | COD/ppm |
| Deamination effluent | 9.2~12 | <5 | <0.5 | 200~300 |
| Index of water reaching standard | 7.2~8.5 | <10 | <0.5 | <90 |
As can be seen from tables 8 to 10, sodium nitrate wastewater is treated by a triple-effect evaporator, certain ammonia nitrogen is concentrated in condensate water, and the content of copper ions is basically lower than 0.05ppm (neglected at 0.08 ppm). But the ammonia nitrogen content is higher, a subsequent deamination tower is required to carry out deamination treatment, the ammonia nitrogen content of the obtained effluent is lower than 5ppm, and the copper ion content is lower than 0.5 ppm. The deamination of the condensed water can reach the ammonia nitrogen content (neglecting individual abnormal data) and the copper content (neglecting individual abnormal data) and can reach the emission requirement (the pH value can be adjusted and discharged). In addition, the COD of the deamination effluent is higher and can not reach the discharge standard though the deamination effluent is treated by a triple-effect evaporator and a deamination tower.
In view of the above problem, as shown in fig. 2, the tin-stripping wastewater resource utilization system provided in the embodiment of the present invention further includes: a flocculation unit 600. The flocculation unit 600 includes a second flocculation tank 601 and a second sedimentation tank 602. The water inlet of the second flocculation tank 601 is communicated with the water outlet of the second treatment unit 200. The water outlet of the second flocculation tank 601 is communicated with the water inlet of the second sedimentation tank 602. The water outlet of the second sedimentation tank 602 is communicated with the water inlet of the desulfurization unit 300.
During specific implementation, the second treatment unit 200 introduces the obtained sodium nitrate wastewater into the second flocculation tank 601, and adds flocculants such as Polyacrylamide (PAM) and sodium polyacrylate into the second flocculation tank 601, so that the flocculants perform flocculation treatment on the sodium nitrate wastewater, thereby further reducing the COD of the deamination effluent. The type and the adding times of the flocculating agent can be adjusted according to the COD of the deamination effluent so as to ensure that the COD of the deamination effluent can reach below 90 ppm.
As shown in fig. 3, an embodiment of the present invention further provides a method for recycling tin-stripping wastewater, where the method for recycling tin-stripping wastewater includes the following steps:
step 100: and (3) carrying out tin precipitation and flocculation treatment on the tin-stripping wastewater by using a sodium hydroxide solution to obtain tin-containing slurry and a clear liquid of waste tin water.
Step 200: and (3) neutralizing the clear liquid of the waste tin water by using a sodium hydroxide solution to remove copper ions contained in the clear liquid of the waste tin water for the first time to obtain a pretreatment solution.
Step 300: and carrying out copper removal treatment on the pretreatment liquid by using sodium sulfide to obtain sodium nitrate wastewater.
Step 400: and removing sulfate radicals and chloride ions contained in the sodium nitrate wastewater by using calcium chloride.
Step 500: distilling the sodium nitrate wastewater to recover sodium nitrate contained in the sodium nitrate wastewater and condensed water generated by distillation.
Step 600: and (4) performing deamination treatment on the condensed water, and discharging deaminated effluent.
Compared with the prior art, the tin-stripping wastewater resource utilization method provided by the embodiment of the invention has the same beneficial effect as the tin-stripping wastewater resource utilization system, and the details are not repeated here.
In the foregoing description of embodiments, the particular features, structures, materials, or characteristics may be combined in any suitable manner in any one or more embodiments or examples.
The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention, and all the changes or substitutions should be covered within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the appended claims.
Claims (9)
1. The utility model provides a tin wastewater resource utilization system moves back which characterized in that includes: the device comprises a first processing unit, a second processing unit, a desulfurization unit, an evaporation unit and a deamination unit; the desulfurizer used by the desulfurization unit is calcium aluminate;
the water inlet of the first processing unit is respectively communicated with a tin-stripping wastewater supply pipeline and an alkali liquor supply pipeline for supplying a sodium hydroxide solution, the water outlet of the first processing unit and the alkali liquor supply pipeline are both communicated with the water inlet of the second processing unit, the water outlet of the second processing unit is communicated with the water inlet of the desulfurization unit, the water outlet of the desulfurization unit is communicated with the water inlet of the evaporation unit, the condensate outlet of the evaporation unit is communicated with the water inlet of the deamination unit, and the outlet of the deamination unit is communicated with an outer discharge pipeline.
2. The resource utilization system for tin-stripping wastewater as claimed in claim 1, wherein the first treatment unit comprises: the tin-removing device comprises a tin-precipitating tank, a first flocculation tank and a first sedimentation tank, wherein a water inlet of the tin-precipitating tank is communicated with a lye supply pipeline and the tin-removing wastewater supply pipeline, a water outlet of the tin-precipitating tank is communicated with a water inlet of the first flocculation tank, a water outlet of the first flocculation tank is communicated with a water inlet of the first sedimentation tank, and a water outlet of the first sedimentation tank is communicated with a water inlet of the second treatment unit.
3. The resource utilization system for tin-stripping wastewater as claimed in claim 1, wherein the second treatment unit comprises: the water inlet of the primary copper removal tank is communicated with the water outlet of the first processing unit and the alkali liquor supply pipeline respectively, the water outlet of the primary copper removal tank is communicated with the water inlet of the secondary copper removal tank, and the water outlet of the secondary copper removal tank is communicated with the water inlet of the evaporation unit.
4. The resource utilization system for tin-stripping wastewater as claimed in any one of claims 1-3, wherein the evaporation unit is a triple-effect evaporator.
5. The tin-stripping wastewater resource utilization system as claimed in any one of claims 1 to 3, wherein the deamination unit is a stripping deamination unit, an ion exchange deamination unit or a bleaching deamination unit.
6. The tin-stripping wastewater resource utilization system as claimed in any one of claims 1 to 3, further comprising: the water inlet of the second flocculation tank is communicated with the water outlet of the second treatment unit, the water outlet of the second flocculation tank is communicated with the water inlet of the second sedimentation tank, and the water outlet of the second sedimentation tank is communicated with the water inlet of the desulfurization unit.
7. The resource utilization system for tin-stripping wastewater as claimed in any one of claims 1 to 3, wherein the desulfurization unit comprises: the water outlet of the second treatment unit is communicated with the water inlet of the desulfurization tank, the water outlet of the desulfurization tank is communicated with the water inlet of the third sedimentation tank, and the water outlet of the third sedimentation tank is communicated with the water inlet of the evaporation unit.
8. A resource utilization method of tin-stripping wastewater is characterized by comprising the following steps:
carrying out tin precipitation and flocculation treatment on the tin-stripping wastewater by using a sodium hydroxide solution to obtain tin-containing slurry and a clear liquid of waste tin water;
neutralizing the waste tin water supernatant by using a sodium hydroxide solution to remove copper ions contained in the waste tin water supernatant for the first time to obtain a pretreatment solution; carrying out copper removal treatment on the pretreatment solution by using sodium sulfide to obtain sodium nitrate wastewater;
removing sulfate radicals and chloride ions contained in the sodium nitrate wastewater by using calcium chloride;
distilling the sodium nitrate wastewater to recover sodium nitrate contained in the sodium nitrate wastewater and condensed water generated by distillation;
and carrying out deamination treatment on the condensed water, and discharging deaminated effluent.
9. The resource utilization method of tin-stripping wastewater according to claim 8, wherein the resource utilization method of tin-stripping wastewater further comprises the following steps of, after the copper removal treatment is performed on the pretreatment liquid by using sodium sulfide to obtain sodium nitrate wastewater, distilling the sodium nitrate wastewater to recover sodium nitrate contained in the sodium nitrate wastewater and condensed water generated by the distillation:
treating the sodium nitrate wastewater by using calcium aluminate to obtain sodium nitrate wastewater containing ettringite precipitates; removing the ettringite precipitate contained in the sodium nitrate wastewater containing the ettringite precipitate;
flocculating the sodium nitrate wastewater by using a flocculating agent to obtain flocculate-containing sodium nitrate wastewater;
removing flocculate contained in the sodium nitrate wastewater containing flocculate.
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