Gas-liquid vulcanization arsenic removal method for high-arsenic waste liquid and reaction system

Abstract

The invention provides a gas-liquid vulcanization arsenic removal method for high-arsenic waste liquid and a reaction system. The method comprises the following steps: S1, providing an additive; the additive comprises sodium hydrogen sulfite; s2, the high-arsenic waste liquid and an additive are subjected to first mixing, and first treatment liquid is obtained; s3, H2S microbubbles are continuously introduced into the first treatment liquid, and after introduction of the H2S microbubbles is finished, second treatment liquid is obtained; the duration of introducing the H2S microbubbles is not less than 10 minutes; in the process of introducing the H2S microbubbles, carrying out second mixing on the first treatment liquid; in the second mixing process, the first treatment liquid is controlled to circularly flow back; the high-arsenic waste liquid contains pentavalent arsenic; and S4, carrying out solid-liquid separation on the second treatment liquid to obtain an arsenic-removed separation liquid. According to the method, the pentavalent arsenic can be rapidly and efficiently removed, the concentration of the pentavalent arsenic is reduced to 50 mg / L or below, and the removal efficiency of the trivalent arsenic is not affected.

Description

Technical Field

[0001] The invention belongs to the field of heavy metal pollution control, and in particular relates to a gas-liquid sulfidation arsenic removal method for high-arsenic waste liquid and a reaction system. Background Art

[0002] The development of copper metallurgical technology has gone through a long process, but copper smelting is still mainly based on pyrometallurgy, and its output accounts for about 85% of the world's copper production. In the copper production process, a large amount of acidic flue gas will be produced. After the flue gas is removed, a large amount of waste acid will be left behind. These waste acids contain a large amount of heavy metals, especially arsenic, which belongs to smelting high-arsenic waste liquid. If there is no effective treatment method, it will not only endanger environmental safety, but also cause incalculable economic losses.

[0003] As a new purification process, arsenic removal by sulfidation has gradually emerged in the copper smelting industry and has been widely used. Arsenic removal by gas-liquid sulfidation is to add hydrogen sulfide gas to the solution to remove arsenic. When using hydrogen sulfide to treat industrial wastewater, the reaction process can be accurately controlled by controlling the amount of hydrogen sulfide added, and the selective removal of metal ions can be achieved. The treatment of arsenic-containing wastewater from copper electrolysis by gas-liquid sulfidation technology is one of the most promising ways to achieve source reduction and clean production in the copper industry. However, from the perspective of industrial application, there are still many problems that have not been solved, such as the slow reaction rate of ordinary gas-liquid sulfidation reaction, and the excessive addition of hydrogen sulfide in industry, which makes the sulfur content too high, which not only increases the cost of the enterprise, but also easily leads to a large amount of hydrogen sulfide gas at the production site, posing a major threat to the personal safety of workers on site. In addition, smelting high-arsenic wastewater usually contains pentavalent arsenic and trivalent arsenic at the same time. Although the hydrogen sulfide arsenic removal method can also remove pentavalent arsenic to a certain extent, it will still cause the separation liquid to still contain a high concentration of pentavalent arsenic.

[0004] In view of this, it is necessary to provide a gas-liquid sulfidation arsenic removal method and reaction system for high-arsenic waste liquid to solve or at least alleviate the technical defects of how to efficiently remove pentavalent arsenic or how to simultaneously and efficiently remove pentavalent arsenic and trivalent arsenic. Summary of the invention

[0005] The main purpose of the present invention is to provide a gas-liquid sulfidation arsenic removal method and reaction system for high-arsenic waste liquid, aiming to solve or at least alleviate the technical problem of how to efficiently remove pentavalent arsenic or how to simultaneously and efficiently remove pentavalent arsenic and trivalent arsenic.

[0006] To achieve the above object, the present invention provides a method for removing arsenic from high-arsenic wastewater by gas-liquid sulfidation, comprising the steps of:

[0007] S1, providing an additive; the additive comprises sodium bisulfite;

[0008] S2, performing a first mixing of the high-arsenic waste liquid and the additive to obtain a first treated liquid;

[0009] S3, continuously introducing H2S microbubbles into the first treatment liquid, and after the introduction of the H2S microbubbles is completed, a second treatment liquid is obtained;

[0010] The duration of introducing the H2S microbubbles is not less than 10 minutes; during the process of introducing the H2S microbubbles, the first treatment liquid is subjected to a second mixing; and during the process of the second mixing, the first treatment liquid is controlled to circulate back;

[0011] The high-arsenic waste liquid contains pentavalent arsenic; the molar ratio of the sodium bisulfite to the pentavalent arsenic is 0.5 to 2:1;

[0012] S4, performing solid-liquid separation on the second treated liquid to obtain an arsenic-removed separated liquid.

[0013] Furthermore, the high-arsenic waste liquid also contains trivalent arsenic, and the molar ratio of the pentavalent arsenic to the trivalent arsenic is 0.8-1.2:0.8-1.2.

[0014] Furthermore, in the high-arsenic waste liquid, the total concentration of arsenic element is 5-25 g / L; and the pH of the high-arsenic waste liquid is 1-2.

[0015] Furthermore, the high-arsenic waste liquid includes smelting high-arsenic waste liquid; the smelting high-arsenic waste liquid includes one or more of dirty acid and copper electrolyte.

[0016] Furthermore, the flow rate of the H2S microbubbles is 4 to 6 m 3 / h.

[0017] Furthermore, the H2S is generated in a hydrogen sulfide synthesis device, the hydrogen sulfide synthesis device supplies gas to a microbubble mechanism through a hydrogen sulfide buffer tank, and the microbubble mechanism is exposed to the first treatment liquid; the H2S is converted into the H2S microbubbles by the microbubble mechanism.

[0018] Furthermore, the duration of introducing the H2S microbubbles is 20 to 120 minutes.

[0019] Furthermore, the additive also includes ammonium ferrous sulfate; the molar ratio of the sodium bisulfite to the ammonium ferrous sulfate is 1.5 to 5:1.

[0020] Furthermore, the first mixing and the second mixing are both performed at room temperature.

[0021] The present invention also provides a reaction system for removing arsenic from high-arsenic waste liquid by gas-liquid sulfidation, the reaction system comprising a hydrogen sulfide synthesis device, a hydrogen sulfide buffer tank, a microbubble mechanism, a sulfidation reaction device and a reflux device; the hydrogen sulfide synthesis device, the hydrogen sulfide buffer tank and the microbubble mechanism are sequentially connected through an air guide pipe, the microbubble mechanism is placed inside the sulfidation reaction device, the reflux device has a liquid inlet and a liquid outlet, the liquid inlet and the liquid outlet are both connected to the sulfidation reaction device;

[0022] The reaction device also includes a control unit, which executes any of the gas-liquid sulfidation arsenic removal methods described above.

[0023] Compared with the prior art, the present invention has at least the following advantages:

[0024] The present invention provides a gas-liquid sulfidation arsenic removal method for high-arsenic waste liquid, which can achieve rapid and efficient removal of pentavalent arsenic, and reduce the concentration of pentavalent arsenic from a high concentration to below 50 mg / L; at the same time, the present invention does not affect the removal efficiency of trivalent arsenic, and can still ensure that the concentration of trivalent arsenic is in a low range. From another perspective, when removing trivalent arsenic, the present invention can simultaneously achieve a significant reduction in pentavalent arsenic after combining sodium bisulfite and ammonium ferrous sulfate (when reacting for 20 minutes, the concentration of pentavalent arsenic is reduced by nearly 90%) even if the reaction time is only about 20 minutes.

[0025] The present invention can enhance the removal effect of pentavalent arsenic in high-arsenic waste liquid by introducing sodium bisulfite and ammonium ferrous sulfate into the gas-liquid sulfidation arsenic removal system, controlling the introduction of H2S microbubbles, and simultaneously performing second mixing and circulating reflux during the introduction process, so that the removal time of arsenic (pentavalent arsenic and trivalent arsenic) contained in the system is short and the arsenic removal rate is high. In addition, the present invention can also increase the contact area and contact time between the high-arsenic waste liquid and the sulfiding agent, reduce the amount of H2S used, and have low processing costs by controlling the introduction of H2S microbubbles and adding a reflux device; the present invention can also avoid the occurrence of a large amount of hydrogen sulfide gas at the production site. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0027] Figure 1 It is a schematic flow diagram of the gas-liquid sulfidation arsenic removal method for high-arsenic waste liquid in the present invention;

[0028] Figure 2The concentration of pentavalent arsenic in the separation solution corresponding to different reaction times in Example 1, Example 2 and Comparative Example 1 of the present invention;

[0029] In the figure, the pentavalent arsenic concentration at 0min corresponds to the initial pentavalent arsenic concentration of the high-arsenic waste liquid; the concentrations at other times are the concentrations of pentavalent arsenic in the separation liquid at the corresponding reaction time; the reaction time is taken as the starting time when hydrogen sulfide microbubbles begin to pass into the first treatment liquid; NaHSO3+(NH4)2Fe(SO4)2 refers to Example 1, NaHSO3 refers to Example 2, and no additive refers to Comparative Example 1;

[0030] Figure 3 The concentration of trivalent arsenic in the separation solution corresponding to different reaction times in Example 1, Example 2 and Comparative Example 1 of the present invention;

[0031] In the figure, the trivalent arsenic concentration at 0min corresponds to the initial trivalent arsenic concentration of the high-arsenic waste liquid; the concentrations at other times are the concentrations of trivalent arsenic in the separation liquid at the corresponding reaction time; the reaction time is taken as the starting time when hydrogen sulfide microbubbles begin to pass into the first treatment liquid; NaHSO3+(NH4)2Fe(SO4)2 refers to Example 1, NaHSO3 refers to Example 2, and no additive refers to Comparative Example 1;

[0032] Figure 4 The XRD diagrams of the As(III) arsenic precipitation product in Analysis Example 1 and the As(V) arsenic precipitation product in Analysis Example 2 of the present invention are shown; in the figure, (a) corresponds to the As(III) arsenic precipitation product at different reaction times, and (b) corresponds to the As(V) arsenic precipitation product at different reaction times;

[0033] Figure 5 The SEM & EDS images of the As(III) precipitation product in the analysis example 1 of the present invention;

[0034] Figure 6 This is the SEM & EDS image of the As(V) precipitation product in Analysis Example 2 of the present invention.

[0035] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with the implementation methods and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0036] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] Furthermore, the technical solutions between the various embodiments of the present invention may be combined with each other, but this must be based on the fact that they can be implemented by ordinary technicians in the field. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0038] When the embodiments give numerical ranges, it should be understood that, unless otherwise specified in the present invention, the two endpoints of each numerical range and any value between the two endpoints can be selected. Unless otherwise defined, all technical and scientific terms used in the present invention and the technical personnel in the field of the prior art and the records of the present invention can also be used to implement the present invention using any method, equipment and material of the prior art similar or equivalent to the method, equipment and material described in the embodiments of the present invention. In Examples 1-2 and Comparative Example 1 of the present invention, the high arsenic waste liquid is prepared from sodium arsenate and sodium arsenite.

[0039] See also Figure 1 As shown, the present invention provides a method for removing arsenic from high-arsenic waste liquid by gas-liquid sulfidation, comprising the steps of:

[0040] S1, providing an additive; the additive comprises sodium bisulfite.

[0041] S2, performing a first mixing of the high-arsenic waste liquid and the additive to obtain a first treated liquid.

[0042] S3, continuously introducing H2S microbubbles into the first treatment liquid to form a gas-liquid sulfidation arsenic removal system; after the introduction of the H2S microbubbles is completed, a second treatment liquid is obtained.

[0043] The invention introduces the additive to greatly enhance the efficiency of gas-liquid sulfidation arsenic removal in high-arsenic waste liquid, greatly shorten the arsenic removal time, and simplify the process operation.

[0044] In the present invention, the duration of the first mixing may be 10 to 20 minutes; the rotation speed of the first mixing may be 150 to 300 r / min.

[0045] In the present invention, the duration of introducing the H2S microbubbles is not less than 10 minutes, not less than 15 minutes, or not less than 120 minutes; further, the duration of introducing the H2S microbubbles is 20 to 120 minutes; preferably, the duration of introducing the H2S microbubbles is 20 to 25 minutes, or 110 to 120 minutes, or 120 to 130 minutes. The introduction flow rate of the H2S microbubbles can be 4 to 6 m 3 / h, the H2S microbubbles are introduced into the first treatment liquid at room temperature; the introduction flow rate is the flow rate of H2S gas entering the first treatment liquid.

[0046] In the present invention, the H2S gas is generated in a hydrogen sulfide synthesis device, and the hydrogen sulfide synthesis device is connected to a microbubble mechanism through a hydrogen sulfide buffer tank, and the microbubble mechanism is exposed to the first treatment liquid; the H2S gas is converted into the H2S microbubbles by the microbubble mechanism, and the microbubble mechanism can be a bubble stone, and the bubble diameter generated by the bubble stone is 0.1 to 2 mm.

[0047] In the hydrogen sulfide synthesis device, the sulfuric acid solution is controlled to be continuously dripped into the NaHS solution, so as to continuously generate H2S; when the generation of H2S is finished, the dripping of the sulfuric acid solution is finished. In the present invention, the H2S generated in the hydrogen sulfide synthesis device enters the hydrogen sulfide buffer tank, and then enters the bubble mechanism to form H2S microbubbles.

[0048] In the present invention, the hydrogen sulfide synthesis device specifically generates H2S in the following manner: taking an appropriate amount of NaHS solution into a reaction vessel (three-necked flask) of the hydrogen sulfide synthesis device, and taking an appropriate amount of 50% dilute sulfuric acid (mass fraction) solution into a dropping funnel, rotating the dropping funnel stopcock to control the 50% dilute sulfuric acid (mass fraction) to be dripped into the reaction vessel of the hydrogen sulfide synthesis device, and the dripping speed is 30 to 45 drops / min; and stirring is performed during the dripping process, and the stirring speed is 200r / min.

[0049] In the present invention, during the process of introducing the H2S microbubbles (during the reaction), the first treatment liquid is subjected to a second mixing; the rotation speed of the second mixing can be 150 to 300 r / min; the first mixing and the second mixing are both carried out at room temperature.

[0050] During the second mixing process, the first treatment liquid is controlled to circulate and reflux. The circulatory reflux is: the first treatment liquid is controlled to continuously flow out and continuously flow into the reaction container of the sulfidation reaction device (the first treatment liquid is in the reaction container of the sulfidation reaction device) through a reflux device (peristaltic pump and liquid guide tube), thereby controlling the first treatment liquid to circulate during the reaction process. The present invention can enhance the utilization efficiency of the sulfiding agent in the gas-liquid sulfidation arsenic removal system, increase the contact area and contact time between the high-arsenic waste liquid and the sulfiding agent, and enhance the removal effect of pentavalent arsenic in the high-arsenic waste liquid by prompting the first treatment liquid to perform the circulatory reflux.

[0051] As a specific description, in the present invention, the rotation speed of the peristaltic pump is 300-400 r / min, and the flow rate of the first treatment liquid during the circulation reflux is 1400-1800 mL / min.

[0052] As an illustration of the high-arsenic waste liquid, the high-arsenic waste liquid contains pentavalent arsenic; the concentration of pentavalent arsenic in the high-arsenic waste liquid can be 5-15 g / L or 8-11 g / L; the molar ratio of the sodium bisulfite to the pentavalent arsenic is 0.5-2:1, further 0.5-0.8:1. Preferably, in order to speed up the treatment of pentavalent arsenic, the additive also includes ammonium ferrous sulfate; the molar ratio of the sodium bisulfite to the ammonium ferrous sulfate is 1.5-5:1, further 1.5-2.5:1; the additive containing the sodium bisulfite and the ferrous sulfate can be called a composite reducing agent.

[0053] The high-arsenic waste liquid also contains trivalent arsenic, and the molar ratio of the pentavalent arsenic to the trivalent arsenic is 0.8-1.2:0.8-1.2. In the high-arsenic waste liquid, the total concentration of arsenic element is 5-25g / L or 15-25g / L; the pH of the high-arsenic waste liquid is 1-2; the pH of the high-arsenic waste liquid can be controlled by adding acid (sulfuric acid). In the present invention, the high-arsenic waste liquid may include or be smelting high-arsenic waste liquid; the smelting high-arsenic waste liquid includes one or more of dirty acid and copper electrolyte.

[0054] S4, performing solid-liquid separation on the second treatment liquid to obtain arsenic-removing separation liquid (purified liquid) and arsenic-containing separation slag (arsenic sulfide slag); in industrial applications, the arsenic-containing separation slag can be refluxed into the sulfidation reaction device.

[0055] It should be understood that in the present invention, the number of solid-liquid separations can be determined according to actual conditions. Although two solid-liquid separations were performed in Examples 1-2 of the present invention, the second solid-liquid separation was mainly for deep filtration to facilitate the detection of pentavalent arsenic and trivalent arsenic.

[0056] The present invention also provides a reaction system for gas-liquid sulfidation and arsenic removal of high-arsenic waste liquid, the reaction system comprising a hydrogen sulfide synthesis device, a hydrogen sulfide buffer tank, a microbubble mechanism, a sulfidation reaction device and a reflux device; the hydrogen sulfide synthesis device, the hydrogen sulfide buffer tank and the microbubble mechanism are sequentially connected through an air guide tube, the microbubble mechanism is placed inside the sulfidation reaction device, the reflux device has a liquid inlet and a liquid outlet, the liquid inlet and the liquid outlet are both connected to the sulfidation reaction device; the reflux device comprises a peristaltic pump and a liquid guide tube. The reaction device also comprises a control unit, the control unit performs any of the above-described gas-liquid sulfidation and arsenic removal methods.

[0057] The present invention utilizes an additive composed of sodium bisulfite and ammonium ferrous sulfate, and reacts at room temperature, pH=1-2 and low H2S introduction conditions, and simultaneously utilizes the circulation of high-arsenic waste liquid and arsenic sulfide slag in a reaction device to increase the contact area and contact time between the high-arsenic waste liquid and the sulfiding agent. The present invention can efficiently remove arsenic from high-arsenic waste liquid, has simple operation, low raw material cost, and strong arsenic removal effect, and can be applied to the fields of copper smelting high-arsenic waste liquid treatment and environmental protection.

[0058] The following are specific examples of the present invention:

[0059] Example 1

[0060] A method for removing arsenic from high-arsenic wastewater by gas-liquid sulfidation, comprising the following steps:

[0061] S1, provides high arsenic wastewater and additives.

[0062] In this embodiment, arsenic in the high-arsenic waste liquid exists in the form of pentavalent arsenic and trivalent arsenic, the concentration of pentavalent arsenic is 10692 mg / L, and the concentration of trivalent arsenic is 10594 mg / L; 200 mL of high-arsenic waste liquid is measured with a measuring cylinder, and the measured high-arsenic waste liquid is transferred to the reaction vessel (three-necked flask) of the sulfidation reaction device with a glass rod, and an appropriate amount of dilute sulfuric acid is added to adjust the pH to 1.

[0063] In this embodiment, the additive consists of sodium bisulfite and ammonium ferrous sulfate; 1.85 g of sodium bisulfite and 2.93 g of ammonium ferrous sulfate are weighed on an electronic balance as the additive.

[0064] S2, pour the above additives into a reaction container containing high-arsenic waste liquid, and stir at a stirring speed of 200 r / min. After stirring for 10 minutes at room temperature, a first treated liquid is obtained; cover the three-necked flask with a cork and fix it with an iron stand for standby use.

[0065] S3, H2S is prepared by a hydrogen sulfide synthesis device, and the H2S gas produced in the hydrogen sulfide synthesis device enters the hydrogen sulfide buffer tank and then flows to the bubble stone; the bubble stone is exposed to the first treatment liquid, and the H2S gas is converted into H2S microbubbles by the bubble stone; the H2S gas is continuously introduced into the first treatment liquid in the form of H2S microbubbles at room temperature, so that a gas-liquid sulfidation and arsenic removal reaction occurs in the reaction vessel of the sulfidation reaction device (carried out at room temperature); the introduction flow rate of the H2S microbubbles is 5m 3 / h (introducing the first treatment liquid).

[0066] After the reaction starts (the reaction start time is the start time of H2S passing into the first treatment liquid), the first treatment liquid is stirred at room temperature, and the stirring speed is controlled to be 200r / min. In this embodiment, the reaction container of the sulfidation reaction device is connected to the liquid inlet and liquid outlet of the reflux device, and the reflux device is composed of a peristaltic pump and a liquid guide tube; during the reaction process, the first treatment liquid (before the ventilation is completed, it is referred to as the first treatment liquid) is controlled by the reflux device to circulate and reflux during the gas-liquid sulfidation dearsenicization reaction; in this embodiment, the speed of the peristaltic pump is 350r / min, and the flow rate of the first treatment liquid during the circulation reflux is 1600mL / min.

[0067] When the reaction is terminated, the introduction of H2S microbubbles in the sulfidation reaction device is terminated, and a second treatment liquid is obtained in the sulfidation reaction device; the second treatment liquid is preliminarily filtered with a qualitative filter paper with a pore size of 30 to 50 microns to obtain a separation residue and a primary filtrate; the obtained primary filtrate is deeply filtered with a filter head with a pore size of 0.22 microns to obtain a separation liquid (secondary filtrate); and the arsenic content of the separation liquid is determined.

[0068] See also Figure 2 As shown, in this embodiment, by atomic fluorescence spectroscopy analysis; after 20 minutes of reaction, the concentration of pentavalent arsenic in the separation liquid is 1160 mg / L; after 1 hour of reaction, the concentration of pentavalent arsenic in the separation liquid is 349 mg / L; after 2 hours of reaction, the concentration of pentavalent arsenic in the separation liquid is 48 mg / L.

[0069] See also Figure 3 As shown, after 10 minutes of reaction, the concentration of trivalent arsenic in the separation liquid was 25 mg / L; after 20 minutes of reaction, the concentration of trivalent arsenic in the separation liquid was 14 mg / L.

[0070] Example 2

[0071] Compared with Example 1, this example changes the preparation batch of high-arsenic waste liquid, and adjusts the additive to sodium bisulfite (without adding ammonium ferrous sulfate), the usage amount of sodium bisulfite is 2.32 g, and other conditions remain unchanged; wherein, the arsenic in the high-arsenic waste liquid exists in the form of pentavalent arsenic and trivalent arsenic, the concentration of pentavalent arsenic is 10790 mg / L, and the concentration of trivalent arsenic is 10483 mg / L.

[0072] See also Figure 2 As shown, in this embodiment, by atomic fluorescence spectroscopy analysis; after 20 minutes of reaction, the concentration of pentavalent arsenic in the separation liquid is 4097 mg / L; after 1 hour of reaction, the concentration of pentavalent arsenic in the separation liquid is 336 mg / L; after 2 hours of reaction, the concentration of pentavalent arsenic in the separation liquid is 49 mg / L.

[0073] See also Figure 3As shown, after 10 minutes of reaction, the concentration of trivalent arsenic in the separation liquid was 28 mg / L; after 20 minutes of reaction, the concentration of trivalent arsenic in the separation liquid was 13 mg / L.

[0074] Comparative Example 1

[0075] Compared with Example 1, this comparative example changed the preparation batch of the high-arsenic waste liquid, and did not add any additives. The high-arsenic waste liquid was directly used as the first treatment liquid, and other conditions remained unchanged; wherein, the arsenic in the high-arsenic waste liquid existed in the form of pentavalent arsenic and trivalent arsenic, the concentration of pentavalent arsenic was 7266 mg / L, and the concentration of trivalent arsenic was 7194 mg / L.

[0076] See also Figure 2 As shown, in this comparative example, after 2 hours of reaction, the concentration of pentavalent arsenic in the separation liquid was 389 mg / L.

[0077] See also Figure 3 As shown, in this comparative example, after reacting for 20 minutes, the concentration of trivalent arsenic in the separation liquid was 10 mg / L.

[0078] Analysis example 1

[0079] Compared with Comparative Example 1, in this analysis example, the high-arsenic waste liquid is adjusted to a trivalent arsenic simulation liquid, and other conditions remain unchanged; wherein, the trivalent arsenic simulation liquid is prepared from sodium arsenite, and the concentration of trivalent arsenic is 7000 mg / L.

[0080] The separated slag obtained in this analysis example is recorded as the As(III) precipitation product. In this analysis example, the phase analysis of the As(III) precipitation product obtained after 5min, 10min, and 20min of reaction is shown in Figure 4 As shown in part (a), the samples with different reaction times are not much different, and all have peaks at 18°, 33°, and 56°. The diffraction peaks are weak and broad, so they are non-crystalline amorphous. After comparison, they are similar to the characteristic peaks of As2S3; therefore, it is inferred that the sulfide precipitation product of As(Ⅲ) contains As2S3.

[0081] In this analysis example, the SEM & EDS analysis of the As(III) precipitation product obtained after 20 minutes of reaction is shown in Figure 5 As shown, it can be seen that the As(Ⅲ) precipitation product is easy to agglomerate into blocks. The surface scanning results show that S:As≈1.5 in the As(Ⅲ) precipitation product, which is consistent with the atomic ratio in As2S3. It is speculated that the product is a single As2S3 precipitate.

[0082] Analysis example 2

[0083] Compared with Comparative Example 1, in this analysis example, the high-arsenic waste liquid is adjusted to a pentavalent arsenic simulation liquid, and other conditions remain unchanged; wherein, the pentavalent arsenic simulation liquid is prepared from sodium arsenate, and the concentration of pentavalent arsenic is 7000 mg / L.

[0084] The separated slag obtained in this analysis example is recorded as the As(V) precipitation product. In this analysis example, the phase analysis of the As(V) precipitation product obtained after 1h, 1.5h, and 2h of reaction is shown in Figure 4 As shown in part (b), the samples with different reaction times are not much different, and all have peaks at 18°, 33°, and 56°. The diffraction peaks are weak and broad, so they are amorphous. After comparison, they are similar to the characteristic peaks of As2S3; therefore, it is speculated that the sulfide precipitation product of As(V) contains As2S3.

[0085] In this analysis example, the SEM & EDS analysis of the As(V) precipitation product obtained after 2 hours of reaction is shown in Figure 6 As shown, it can be seen that the As(V) precipitation product has good dispersion. The surface scanning results show that S:As≈2.6 in the As(V) precipitation product. It is speculated that the product is composed of As2S3 and S, but there is no obvious characteristic peak of S in the XRD of As(V).

[0086] The above technical solutions of the present invention are only preferred embodiments of the present invention, and the patent scope of the present invention is not limited thereto. All equivalent structural changes made by using the contents of the present invention specification and drawings under the technical concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A method for removing arsenic from high-arsenic wastewater by gas-liquid sulfidation, characterized in that: Includes steps: S1, providing an additive; the additive comprises sodium bisulfite; S2, performing a first mixing of the high-arsenic waste liquid and the additive to obtain a first treated liquid; S3, continuously introducing H2S microbubbles into the first treatment liquid, and after the introduction of the H2S microbubbles is completed, a second treatment liquid is obtained; The duration of introducing the H2S microbubbles is not less than 10 minutes; during the process of introducing the H2S microbubbles, the first treatment liquid is subjected to a second mixing; and during the process of the second mixing, the first treatment liquid is controlled to circulate back; The high-arsenic waste liquid contains pentavalent arsenic; the molar ratio of the sodium bisulfite to the pentavalent arsenic is 0.5 to 2:1; S4, performing solid-liquid separation on the second treated liquid to obtain an arsenic-removed separated liquid.

2. The gas-liquid sulfidation arsenic removal method according to claim 1, characterized in that: The high-arsenic waste liquid also contains trivalent arsenic, and the molar ratio of the pentavalent arsenic to the trivalent arsenic is 0.8-1.2:0.8-1.

2.

3. The gas-liquid sulfidation arsenic removal method according to claim 1, characterized in that: The total concentration of arsenic in the high-arsenic waste liquid is 5-25 g / L; the pH of the high-arsenic waste liquid is 1-2.

4. The gas-liquid sulfidation arsenic removal method according to claim 1, characterized in that: The high-arsenic waste liquid includes smelting high-arsenic waste liquid; the smelting high-arsenic waste liquid includes one or more of dirty acid and copper electrolyte.

5. The gas-liquid sulfidation arsenic removal method according to claim 1, characterized in that: The flow rate of H2S microbubbles is 4-6m 3 / h.

6. The gas-liquid sulfidation arsenic removal method according to claim 1, characterized in that: The H2S is generated in a hydrogen sulfide synthesis device, and the hydrogen sulfide synthesis device supplies gas to a microbubble mechanism through a hydrogen sulfide buffer tank, and the microbubble mechanism is exposed to the first treatment liquid; the H2S is converted into the H2S microbubbles by the microbubble mechanism.

7. The gas-liquid sulfidation arsenic removal method according to claim 1, characterized in that: The time for introducing the H2S microbubbles is 20 to 120 minutes.

8. The gas-liquid sulfidation arsenic removal method according to claim 1, characterized in that: The additive further includes ammonium ferrous sulfate; the molar ratio of the sodium bisulfite to the ammonium ferrous sulfate is 1.5 to 5:

1.

9. The gas-liquid sulfidation arsenic removal method according to claim 1, characterized in that: The first mixing and the second mixing are both performed at room temperature.

10. A reaction system for removing arsenic from high-arsenic waste liquid by gas-liquid sulfidation, characterized in that: The reaction system comprises a hydrogen sulfide synthesis device, a hydrogen sulfide buffer tank, a microbubble mechanism, a sulfidation reaction device and a reflux device; the hydrogen sulfide synthesis device, the hydrogen sulfide buffer tank and the microbubble mechanism are sequentially connected through an air guide pipe, the microbubble mechanism is placed inside the sulfidation reaction device, and the reflux device has a liquid inlet and a liquid outlet, and the liquid inlet and the liquid outlet are both connected to the sulfidation reaction device; The reaction device also includes a control unit, which executes the gas-liquid sulfidation arsenic removal method as described in any one of claims 1-9.

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