Method and device for deeply purifying arsenic solution and preparing high-purity arsenic oxide

Abstract

The invention discloses a method and a device for deeply purifying an arsenic solution and preparing high-purity arsenic oxide. The method comprises the following steps: oxidizing antimony impurities in an arsenic solution, precipitating, deeply removing, adding a reducing agent to reduce pentavalent arsenic in the solution into trivalent arsenic, decomposing, evaporating, cooling and crystallizing to obtain the high-purity arsenic trioxide. Wherein oxidation precipitation is carried out in a purification tank, reduction is carried out in a reduction tank, the purification tank and the reduction tank are located in the same box body and are separated by a filter screen and a partition plate in the middle, precipitated arsenic antimonate generated after purification in the purification tank is intercepted through the filter screen, and filtrate enters the reduction tank; during reaction, the partition plate is started for use to prevent the solution from flowing. The filtrate enters a reduction tank, reducing agents such as sulfur dioxide are introduced, pentavalent arsenic in the solution is further reduced to form trivalent arsenic, and a high-purity arsenic trioxide product (As2O3 is larger than or equal to 99.5%, and Sb is smaller than or equal to 0.05%) is prepared.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of metallurgy, and relates to a method and device for deep purification of an arsenic solution and preparation of high-purity arsenic oxide. BACKGROUND

[0002] In non-ferrous metallurgy, arsenic has strong affinity with metals such as copper, nickel, cobalt, lead and zinc, and often enters and migrates, enriches and circulates in the smelting process in the form of mineral paragenesis or process by-product. The arsenic salts and arsenic oxides formed by arsenic-containing wastewater, waste residue and arsenic-containing flue gas have high toxicity and environmental persistence, and if improperly disposed, will cause safety and environmental risks such as equipment corrosion, process fluctuation and non-compliance of discharge. Therefore, how to realize the "open circuit" removal of arsenic in the smelting system and convert and recycle it in a stable and controllable form has become a key problem of common concern in the industry.

[0003] The existing technical route mainly includes: converting arsenic into arsenic trioxide (As2O3) for collection and utilization, or fixing it into an arsenate solid phase to reduce its migration. However, due to the similar chemical properties of arsenic and antimony, As-Sb association and entrainment often occurs in the traditional As2O3 preparation process: the antimony content in the conventional product-grade arsenic trioxide (As2O3≥99%, Sb≤0.8%) is often maintained at about 0.5%, which is difficult to meet the more stringent impurity control requirements of electronic-grade white arsenic: Sb≤0.05%, As2O3≥99.5%. This leads to complex subsequent purification steps, significant increase in energy consumption and cost, and also increases the pressure of secondary pollution control.

[0004] The application designs a method and device for deep purification of an arsenic solution and preparation of high-purity arsenic oxide, which can prepare high-purity arsenic trioxide by using common chemical reagents and simple process, and greatly reduces the cost and improves the product quality. SUMMARY

[0005] In view of the deficiencies of the prior art, a first object of the application is to provide a method for deep purification of an arsenic solution and preparation of high-purity arsenic oxide.

[0006] A second object of the application is to provide a device for deep purification of an arsenic solution and preparation of high-purity arsenic oxide.

[0007] In order to achieve the above objects, the following technical solutions are adopted:

[0008] The method for deep purification of an arsenic solution and preparation of high-purity arsenic oxide of the application comprises the following steps: adding an oxidizing agent to an arsenic-containing solution, carrying out an oxidation reaction, performing solid-liquid separation, obtaining an arsenic antimonate precipitate and an arsenic-containing filtrate, adding a reducing agent to the arsenic-containing filtrate, carrying out a reduction reaction, and crystallizing to obtain high-purity arsenic trioxide. The arsenic-containing solution contains arsenic and antimony.

[0009] In this invention, the purified arsenic-containing solution mainly contains AsO4. 3- AsO3 3- , H3AsO4, H3AsO3, HAsO2, SbO + Antimony exists in forms such as HSb(OH)6. When an oxidizing agent is introduced, antimony undergoes oxidation, with trivalent antimony being oxidized to pentavalent antimony: SbO. + +O2+3H2O=HSb(OH)6; oxidized HSb(OH)6 reacts with AsO3 3- The reaction produces AsSbO4 precipitate: HSb(OH)6 + H3AsO3 = AsSbO4↓ + 5H2O, AsO + + HSb(OH)6=AsSbO4↓+H + ↑+3H2O. After precipitating and filtering arsenic antimony, the arsenic-containing filtrate can be reduced to obtain high-purity arsenic trioxide.

[0010] In a preferred embodiment, the arsenic-containing solution is selected from one of the following: arsenic sulfide atmospheric pressure leaching solution, arsenic sulfide high pressure oxygen leaching solution, and copper electrolyte.

[0011] In a preferred embodiment, the oxidant is selected from air, oxygen, and hydrogen peroxide, with hydrogen peroxide being the preferred choice.

[0012] In a preferred embodiment, the amount of oxidant added is 1-1.2 times the theoretical amount required to oxidize trivalent antimony to pentavalent antimony.

[0013] In a preferred embodiment, the pH of the oxidation reaction is 1-7, preferably 3-5; the temperature of the oxidation reaction is 10-60℃, preferably 40-60℃; and the time of the oxidation reaction is 0.5-4h, preferably 0.5-1h.

[0014] Experiments have shown that controlling the pH of the oxidation reaction to below 7 and the temperature to not exceed 60°C can reduce the oxidation of trivalent arsenic to pentavalent arsenic, thus preventing arsenic loss. Since these parameters are controlled within the range of this invention, ultimately…

[0015] In a preferred embodiment, the oxidation reaction is carried out under stirring at a speed of 200-300 rpm. Experiments have shown that controlling the speed within this range yields the best results in oxidation precipitation and impurity removal. If the speed is too high, colloid formation becomes significant, fine particles increase, and the filter screen becomes more difficult to scrape off; if the speed is too low, the trivalent antimony reaction will be incomplete, resulting in obvious stratification within the tank and a higher Sb content in the filtrate.

[0016] In a preferred embodiment, the reducing agent is selected from sodium sulfite, sulfur dioxide, and formaldehyde, with sodium sulfite being the most preferred.

[0017] In a preferred embodiment, the amount of reducing agent added is 1.1-1.3 times the molar amount of the added oxidizing agent.

[0018] In a preferred embodiment, the temperature of the reduction reaction is 10-80℃, preferably 40-50℃, and the reaction time is 0.5-2h, preferably 2h.

[0019] In a preferred embodiment, the reduction reaction is carried out under stirring at a speed of 100-200 rpm.

[0020] Stirring provides suction to the solution flow, and at the same time, it promotes full contact between the arsenic solution and the reducing agent, resulting in a more complete reaction.

[0021] In a preferred embodiment, during crystallization, the temperature is first raised to 60-100℃, preferably 85-95℃, and then lowered to 20-40℃, preferably 20℃, for crystallization. The crystallization time is 0.5-3 hours, preferably 1 hour.

[0022] In the preferred embodiment, an arsenic-containing solution is placed in a purification tank, and then an oxidant is added to the arsenic-containing solution to carry out an oxidation reaction. After the reaction, solid-liquid separation is performed through a filter screen. The resulting arsenic antimony precipitate remains in the purification tank, and the filtrate flows into a reduction tank through the outlet in the partition. A reduction reaction is carried out in the reduction tank, and crystallization occurs to obtain high-purity arsenic trioxide.

[0023] The purification tank and the reduction tank are located in the same box. A filter screen and a partition are installed at intervals in the middle of the box. The purification tank and the reduction tank are located on both sides of the filter screen and the partition, respectively.

[0024] Experiments have shown that placing the purification tank and reduction tank in the same chamber, separated by a partition, allows for efficient filtration. During filtration, the outlet on the partition is opened to trap the precipitate produced after purification, and the filtrate enters the reduction tank. During reaction, the outlet on the partition is closed to prevent solution flow. For continuous production, the solution level in the oxidation precipitation zone can be raised by 2-5 cm to create a level difference and achieve automatic filtration, significantly simplifying the process. More importantly, experiments have revealed that because a filter screen is placed near the purification tank, the reaction solution remains in contact with the screen during the reaction. The screen surface acts as an adhesion substrate for heterogeneous nucleation and crystal growth, reducing the critical nucleation energy barrier and critical supersaturation, shortening the induction period, trapping nascent microcrystals, and allowing them to grow into separable particles. This improves the precipitation rate of arsenic antimonate, ultimately resulting in higher purity of arsenic trioxide.

[0025] In a preferred embodiment, the liquid level in the purification tank is 2-5 cm higher than the liquid level in the reduction tank.

[0026] In a preferred embodiment, the filter screen consists of an upper part with large pores and a lower part with micropores. The upper part with large pores comprises the upper three-quarters of the filter screen, and the lower part with micropores comprises the lower one-quarter of the filter screen. The mesh diameter of the upper part with large pores is 150-300 μm, and the mesh diameter of the lower part with micropores is 0.2-0.5 μm.

[0027] In this invention, the upper part of the large pores of the filter screen is a taut coarse filter screen (mesh size: 150-300 μm) to facilitate the formation of arsenic antimony crystal nuclei and improve precipitation efficiency, while the lower part of the micropores is a ceramic micro filter screen (mesh size: 0.2-0.5 μm) to facilitate the retention of arsenic antimony and prevent arsenic antimony precipitate from entering the reduction tank.

[0028] In a further preferred embodiment, a flow guide baffle is attached to the upper part of the large pores of the filter screen near the reduction tank. The flow guide baffle prevents the reaction liquid from flowing into the reduction tank through the upper part of the large pores of the filter screen, and instead allows it to be intercepted by the micropores at the bottom before entering the reduction tank.

[0029] In a preferred embodiment, the partition is provided with three parallel liquid outlets at different heights, and each of the three liquid outlets is equipped with a switch to control the opening and closing of the liquid outlets. The lower end of each liquid outlet is located at 2 / 3 of the height of the partition.

[0030] Three outlets are provided in the partition to allow the filtrate from the purification tank to flow into the reduction tank. By setting an outlet at the top of the partition, the guide baffle can ensure that the newly entered solution comes to the bottom of the purification tank to participate in the oxidation reaction before flowing into the reduction tank, instead of flowing directly into the reduction tank from the top without reacting, thus enabling continuous production.

[0031] Furthermore, the switch is a shaft-driven movable stop and / or a pressure-sensitive switch. When set as a pressure-sensitive switch, the rise in liquid level in the purification tank leads to a pressure increase, triggering the pressure switch. After the liquid is discharged and the pressure is released, it automatically closes. This requires the coordination of the reaction time of the purification tank and the automated control of the liquid level rise (i.e., the flow rate of the arsenic solution inlet).

[0032] The present invention also provides an apparatus for deep purification of arsenic solution and preparation of high-purity arsenic oxide. The apparatus includes a box, in which a filter screen and a partition are spaced apart in the middle. The two sides of the filter screen and the partition are a purification tank and a reduction tank, respectively. The partition is provided with a liquid outlet, and a switch is provided in the liquid outlet for controlling the opening and closing of the liquid outlet.

[0033] In a preferred embodiment, the top cover of the chamber is provided with a liquid inlet located above the purification tank for introducing arsenic-containing solution. The top cover of the chamber is also provided with a residual gas outlet located above the reduction tank to prevent pressure buildup inside the chamber. In this invention, both the arsenic solution inlet and the residual gas outlet are integrally formed on the top cover. The residual gas outlet is designed to prevent excessive SO2 from causing internal pressure increases and solution backflow, and it can also be connected to an air intake device for recycling.

[0034] In a preferred embodiment, the chamber is equipped with two independently controlled jacketed heat exchangers. The first jacketed heat exchanger is used to control the temperature of the purification tank, and the second jacketed heat exchanger is used to control the temperature of the reduction tank. Using jacketed heat exchangers is not only cost-effective, but also avoids the inconvenience of cleaning settled sludge compared to jacketed-coil heat exchangers.

[0035] In a preferred embodiment, both the purification tank and the reduction tank are equipped with stirring paddles. The stirring paddles not only improve reaction efficiency but also temperature control efficiency.

[0036] In a preferred embodiment, the housing is equipped with a filter screen scraper mechanism, which consists of a scraper, a filter screen, and a flow guide baffle. The scraper is used to scrape away accumulated dirt from the filter screen. The filter screen consists of an upper part with large pores and a lower part with micropores. The upper part with large pores is the upper three-quarters of the filter screen, and the lower part with micropores is the lower one-quarter of the filter screen. The mesh diameter of the upper part with large pores is 150-300 μm, and the mesh diameter of the lower part with micropores is 0.2-0.5 μm. A flow guide baffle is attached to the side of the upper part of the filter screen near the reduction tank.

[0037] In a preferred embodiment, the partition is provided with three parallel liquid outlets at different heights, and each of the three liquid outlets is equipped with a switch to control the opening and closing of the liquid outlets. The lower end of each liquid outlet is located at 2 / 3 of the height of the partition.

[0038] Furthermore, the switch is a shaft-driven movable stop and / or a pressure-sensitive switch.

[0039] In a preferred embodiment, a sedimentation base is fixedly connected to the bottom of the box body. The bottom part of the sedimentation base located in the purification tank and the reduction tank adopts a surface with an inclined angle and is provided with a mud guide channel with an inclined angle. The two sides of the sedimentation base are respectively provided with an AsSbO4 sedimentation mud outlet and an As2O3 product outlet.

[0040] In a further preferred embodiment, both the AsSbO4 precipitate outlet and the As2O3 product outlet are equipped with sludge discharge valves for convenient periodic cleaning.

[0041] In a further preferred embodiment, the bottom of the tank is also provided with a reducing agent pipe and an oxidizing agent pipe, the reducing agent pipe being used to deliver a reducing agent into the reduction tank, and the oxidizing agent pipe being used to deliver an oxidizing agent into the oxidation tank.

[0042] In a further preferred embodiment, the reducing agent pipe, the oxidizing agent pipe, and the precipitation base are formed together and arranged symmetrically. This forming method ensures that both the reducing agent and the oxidizing agent are introduced from the bottom, and with the aid of a stirring paddle, the problem of incomplete reaction can be minimized.

[0043] In a preferred embodiment, the purification tank is equipped with a temperature sensor and a pH meter, while the reduction tank is equipped with a temperature sensor and a liquid level monitor. This arrangement facilitates monitoring of the reaction process and simultaneously ensures control of the liquid level to prevent backflow.

[0044] Beneficial effects

[0045] This invention provides a method for deep purification of arsenic solution and preparation of high-purity arsenic oxide. The arsenic-containing solution purified in this invention is mainly composed of AsO4. 3- AsO3 3- , H3AsO4, H3AsO3, HAsO2, SbO + Arsenic trioxide exists in forms such as HSb(OH)6. First, an oxidant is added to an arsenic-containing solution to oxidize the antimony. The trivalent antimony is oxidized to the pentavalent form and reacts with arsenic to obtain arsenic antimony precipitate. After filtration, the filtrate is reduced to obtain high-purity arsenic trioxide.

[0046] In this invention, precipitation takes place in a purification tank, while reduction takes place in a reduction tank. The purification tank and reduction tank are located in the same chamber and separated by a partition. During filtration, the outlet on the partition is opened to trap the precipitate generated after purification, and the filtrate enters the reduction tank. During the reaction, the outlet on the partition is closed to prevent the solution from flowing. If continuous production is required, the solution level in the oxidation precipitation zone can be raised by 2-5 cm to create a level difference and complete automatic filtration, which can greatly simplify the process. More importantly, experiments have shown that because a filter screen is set on the side near the purification tank, the reaction solution is in constant contact with the filter screen during the reaction. The surface of the filter screen can serve as an adhesion substrate for heterogeneous nucleation and crystal growth, which can reduce the critical nucleation energy barrier and critical supersaturation, shorten the induction period, trap the nascent microcrystals, and allow them to grow into separable particles, thereby increasing the precipitation rate of arsenic antimonate and ultimately resulting in higher purity of arsenic trioxide. The final product obtained by this invention has As2O3 ≥ 99.5% and Sb ≤ 0.05%, which meets the requirements for electronic-grade arsenic raw materials. Attached Figure Description

[0047] Figure 1The process flow diagram for the deep purification of arsenic solution and the preparation of high-purity arsenic oxide according to the present invention is shown below.

[0048] Figure 2 An isometric view of the apparatus for deep purification of arsenic solution and preparation of high-purity arsenic oxide according to the present invention;

[0049] Figure 3 An internal isometric view (without top cover and jacketed heat exchanger) of the arsenic solution deep purification and high-purity arsenic oxide preparation device of the present invention.

[0050] Figure 4 An internal side view of the device for deep purification of arsenic solution and preparation of high-purity arsenic oxide according to the present invention (without top cover and jacketed heat exchanger).

[0051] Figure 5 A front view of the apparatus for deep purification of arsenic solution and preparation of high-purity arsenic oxide according to the present invention;

[0052] Figure 6 A side view of the apparatus for deep purification of arsenic solution and preparation of high-purity arsenic oxide according to the present invention;

[0053] Figure 7 A cross-section of the apparatus for deep purification of arsenic solution and preparation of high-purity arsenic oxide according to the present invention. Figure 1 (correspond Figure 6 (AA in the text)

[0054] Figure 8 A bottom view of the apparatus for deep purification of arsenic solution and preparation of high-purity arsenic oxide according to the present invention;

[0055] Figure 9 A cross-section of the apparatus for deep purification of arsenic solution and preparation of high-purity arsenic oxide according to the present invention. Figure 2 (correspond Figure 8 (BB in the middle)

[0056] Figure 10 A schematic diagram of the filter scraper mechanism of the device for deep purification of arsenic solution and preparation of high-purity arsenic oxide;

[0057] Figure 11 A schematic diagram of the movable baffle mechanism of the device for deep purification of arsenic solution and preparation of high-purity arsenic oxide.

[0058] in, Figures 1-11In the diagram, 1. Top cover; 1a. Liquid inlet; 1b. Residual gas outlet; 2. Jacketed heat exchanger; 2a. Steam outlet (coolant inlet) of the jacketed heat exchanger in the purification tank; 2b. Steam inlet (coolant outlet) of the jacketed heat exchanger in the purification tank; 2c. Steam outlet (coolant inlet) of the jacketed heat exchanger in the reduction tank; 2d. Steam outlet (coolant inlet) of the jacketed heat exchanger in the reduction tank; 2e. Inner cavity of the jacketed heat exchanger in the purification tank; 2f. Inner cavity of the jacketed heat exchanger in the reduction tank; 3. Sedimentation base; 3a. As2O3 product outlet; 3b. AsSbO4 sedimentation mud outlet; 3c. Reducing agent pipeline; 3d. Oxidizing agent pipeline; 4a. Stirring paddle in the purification tank; 4b. Stirring paddle in the reduction tank; 5. Movable baffle; 5a. First movable baffle; 5b. Second movable baffle; 5c. 6. Third movable stop; 7. Filter scraper mechanism; 6a. Scraper; 6b. Filter screen; 6c. Flow guide baffle; 7. Partition; 8. Purification tank; 9. Reduction tank;

[0059] M - Motor; T - Temperature sensor; V - Flow meter; FS - Liquid level monitor; Val - Sludge discharge valve.

[0060] Figure 12 A sample image of the arsenic trioxide product of this invention. Detailed Implementation

[0061] To illustrate the features of the present invention, the present invention will be described in conjunction with embodiments.

[0062] This invention provides an apparatus for the deep purification of arsenic solution and the preparation of high-purity arsenic oxide:

[0063] like Figure 2 , Figure 3 As shown: The device includes a box, in which a filter screen and a partition are spaced apart in the middle. The two sides of the filter screen and the partition are a purification tank and a reduction tank, respectively. The partition is provided with a liquid outlet, and a switch is provided in the liquid outlet to control the opening and closing of the liquid outlet.

[0064] like Figure 2 , Figure 6 As shown: The top cover of the chamber is equipped with a liquid inlet, located above the purification tank, for introducing arsenic-containing solution. The top cover also has a residual gas outlet, located above the reduction tank, to prevent pressure buildup inside the chamber. In this invention, both the arsenic solution inlet and the residual gas outlet are integrally formed on the top cover. The residual gas outlet is designed to prevent excessive SO2 from causing internal pressure increases and solution backflow, and it can also be connected to an air intake device for recycling.

[0065] Furthermore, such as Figure 7As shown, the housing is equipped with two independently controlled jacketed heat exchangers. The first jacketed heat exchanger is used to control the temperature of the purification tank, and the second jacketed heat exchanger is used to control the temperature of the reduction tank. Using jacketed heat exchangers is not only cost-effective, but also avoids the inconvenience of cleaning settled sludge compared to jacketed-coil heat exchangers. Figure 8 The image shows a bottom view of an apparatus for deep purification of arsenic solution and preparation of high-purity arsenic oxide. The diagram shows the steam outlet (coolant inlet) of the jacketed heat exchanger in the purification tank; the steam inlet (coolant outlet) of the jacketed heat exchanger in the purification tank; the steam outlet (coolant inlet) of the jacketed heat exchanger in the reduction tank; and the steam outlet (coolant inlet) of the jacketed heat exchanger in the reduction tank.

[0066] Furthermore, such as Figure 3 , Figure 7 As shown, stirring paddles are installed in both the purification tank and the reduction tank. The stirring paddles not only improve reaction efficiency but also temperature control efficiency.

[0067] Furthermore, such as Figure 4 , Figure 10 As shown, the housing is equipped with a filter screen scraper mechanism, which consists of a scraper, a filter screen, and a flow guide baffle. The scraper is used to scrape away accumulated dirt from the filter screen. The filter screen consists of an upper part with large pores and a lower part with micropores. The upper part with large pores comprises the upper three-quarters of the filter screen, and the lower part with micropores comprises the lower one-quarter of the filter screen. The mesh diameter of the upper part with large pores is 150-300 μm, and the mesh diameter of the lower part with micropores is 0.2-0.5 μm. Figure 9 As shown, a flow guide baffle is attached to the upper part of the large holes of the filter screen near the reduction tank.

[0068] Furthermore, such as Figure 3 , Figure 11 The partition shown has three parallel liquid outlets, each equipped with a switch to control the opening and closing of the liquid outlets. The lower end of each liquid outlet is located at 2 / 3 of the height of the partition.

[0069] Furthermore, the switch is a shaft-driven movable stop and / or a pressure-sensitive switch;

[0070] like Figure 5 As shown, a sedimentation base is fixedly connected to the bottom of the box body. The bottom part of the sedimentation base located in the purification tank and the reduction tank adopts a surface with an inclined angle and is provided with a mud guide channel with an inclined angle. The two sides of the sedimentation base are respectively provided with an AsSbO4 sedimentation mud outlet and an As2O3 product outlet.

[0071] Both the AsSbO4 precipitate outlet and the As2O3 product outlet are equipped with sludge discharge valves for convenient periodic cleaning.

[0072] Furthermore, such asFigure 6 As shown, the bottom of the tank is also provided with a reducing agent pipe and an oxidizing agent pipe. The reducing agent pipe is used to transport the reducing agent into the reduction tank, and the oxidizing agent pipe is used to transport the oxidizing agent into the oxidation tank.

[0073] The reducing agent pipe, oxidizing agent pipe, and precipitation base are molded together and arranged symmetrically. This molding method ensures that both the reducing agent and oxidizing agent are introduced from the bottom, and with the addition of a stirring paddle, incomplete reactions can be minimized.

[0074] Furthermore, the purification tank is equipped with a temperature sensor and a pH meter, while the reduction tank is equipped with a temperature sensor and a liquid level monitor. This arrangement facilitates monitoring of the reaction process and simultaneously ensures control of the liquid level to prevent backflow.

[0075] The following Examples 1-3 and 5 are all completed using the above-described device.

[0076] Example 1

[0077] Add 500 ml of arsenic solution (containing 70 g / L arsenic and 0.6 g / L antimony) to the oxidation tank, adjust the pH of the solution to 5, heat to 60°C, and then add 1.2 times the theoretical amount of hydrogen peroxide (the amount of hydrogen peroxide added is 1.2 times the theoretical amount needed to oxidize trivalent antimony to pentavalent antimony). Oxidize and precipitate for 0.5 h, controlling the stirring speed at 250 rpm during the oxidation process. Then filter the reaction solution through the lower part of the micropores of the filter screen, and then enter the reduction tank through the liquid inlet of the partition. In the reduction precipitation zone, add sodium sulfite (the amount of sodium sulfite added is 1.2 times the molar amount of hydrogen peroxide) to the solution for reduction for 1 h at a reduction temperature of 50°C. During the reduction process, control the stirring speed at 130 rpm. After the reduction reaction is completed, first raise the temperature to 80°C and then lower it to 20°C. After evaporation and crystallization for 1 h, the mass fraction of arsenic trioxide product is 99.6% As2O3 and 0.03% Sb.

[0078] Example 2

[0079] The other conditions were the same as in Example 1, except that 500 ml of arsenic sulfide leaching solution (containing 50 g / L of arsenic and 0.3 g / L of antimony) was used, the pH of the solution was adjusted to 4, heated to 95°C, and oxygen was introduced to oxidize and precipitate the solution for 4 hours. The solution was equipped with a filter plate, and sodium sulfite was added to the solution in the reduction precipitation zone for 0.5 hours for reduction. After evaporation and crystallization, arsenic trioxide product with 99.1% As2O3 and 0.2% Sb was obtained.

[0080] Example 3

[0081] The other conditions were the same as in Example 1, except that 1000 ml of arsenic sulfide high-pressure oxygen leaching solution (containing 60 g / L of arsenic and 0.1 g / L of antimony) was oxidized and precipitated with 1.5 times the theoretical amount of hydrogen peroxide at 20°C for 6 hours. The solution was equipped with a filter plate, and sodium sulfite was added to the solution in the reduction precipitation zone for 2 hours of reduction. After evaporation and crystallization, arsenic trioxide product with 98.5% As2O3 and 0.3% Sb was obtained.

[0082] Example 4

[0083] The other conditions were the same as in Example 1, except that 1000 ml of arsenic sulfide high-pressure oxygen leaching solution (containing 60 g / L of arsenic and 0.8 g / L of antimony) was oxidized and precipitated with 2 times the theoretical amount of hydrogen peroxide at 40°C for 1.0 h without a filter screen or separator. After vacuum filtration, the temperature of the filtrate was controlled at 20°C, and sodium sulfite was added for reduction for 2 h. After evaporation and crystallization, arsenic trioxide product with 99.0% As2O3 and 0.5% Sb was obtained.

[0084] Example 5

[0085] The other conditions were the same as in Example 1, except that 1000 ml of arsenic sulfide high-pressure oxygen leaching solution (containing 70 g / L of arsenic and 1.0 g / L of antimony) was oxidized and precipitated with 1.1 times the theoretical amount of hydrogen peroxide at 50°C for 1.5 h to obtain arsenic trioxide product with 99.7% As2O3 and 0.05% Sb.

Claims

1. A method for deep purification of arsenic solution and preparation of high-purity arsenic oxide, characterized in that: An oxidizing agent is added to an arsenic-containing solution, an oxidation reaction is carried out, and solid-liquid separation is performed to obtain arsenic antimony precipitate and an arsenic-containing filtrate. A reducing agent is added to the arsenic-containing filtrate, a reduction reaction is carried out, and crystallization occurs to obtain high-purity arsenic trioxide. The arsenic-containing solution contains arsenic and antimony.

2. The method for deep purification of arsenic solution and preparation of high-purity arsenic oxide according to claim 1, characterized in that: The arsenic-containing solution is selected from one of the following: arsenic sulfide atmospheric pressure leaching solution, arsenic sulfide high pressure oxygen leaching solution, and copper electrolyte.

3. The method for deep purification of arsenic solution and preparation of high-purity arsenic oxide according to claim 1, characterized in that: The oxidant is selected from one of air, oxygen, and hydrogen peroxide; The amount of oxidant added is 1-1.2 times the theoretical amount needed to oxidize trivalent antimony to pentavalent antimony; The oxidation reaction is carried out at a pH of 1-7, at a temperature of 10-60℃, and for a time of 0.5-4 hours. The oxidation reaction is carried out under stirring at a speed of 100-200 rpm.

4. The method for deep purification of arsenic solution and preparation of high-purity arsenic oxide according to claim 1, characterized in that: The reducing agent is selected from sodium sulfite, sulfur dioxide, and formaldehyde; The amount of reducing agent added is 1.1-1.3 times the molar amount of the oxidizing agent added; The reduction reaction is carried out at a temperature of 10-80℃ and for a duration of 10-80℃. The reduction reaction is carried out under stirring at a speed of 100-200 rpm. During the crystallization process, the temperature is first raised to 60-80℃ and then lowered to 20-40℃. The crystallization time is 0.5-3 hours.

5. The method for deep purification of arsenic solution and preparation of high-purity arsenic oxide according to claim 1, characterized in that: Arsenic-containing solution is placed in a purification tank, and then an oxidant is added to the arsenic-containing solution to carry out an oxidation reaction. After the reaction, solid-liquid separation is performed through a filter screen. The resulting arsenic antimony precipitate remains in the purification tank, and the filtrate flows into a reduction tank through the outlet in the partition. A reduction reaction is carried out in the reduction tank, and crystallization occurs, thus obtaining high-purity arsenic trioxide. The purification tank and the reduction tank are located in the same box. A filter screen and a partition are installed at intervals in the middle of the box. The purification tank and the reduction tank are located on both sides of the filter screen and the partition, respectively.

6. The method for deep purification of arsenic solution and preparation of high-purity arsenic oxide according to claim 5, characterized in that: The liquid level in the purification tank is 2-5 cm higher than the liquid level in the reduction tank. The filter screen consists of an upper part with large pores and a lower part with micropores. The upper part with large pores is the upper three-quarters of the filter screen, and the lower part with micropores is the lower one-quarter of the filter screen. The mesh diameter of the upper part with large pores is 150-300 μm, and the mesh diameter of the lower part with micropores is 0.2-0.5 μm. A flow guide baffle is attached to the upper part of the large holes of the filter screen near the reduction tank. In a preferred embodiment, the partition is provided with three parallel liquid outlets at different heights, and each of the three liquid outlets is equipped with a switch to control the opening and closing of the liquid outlets. The lower end of each liquid outlet is located at 2 / 3 of the height of the partition. The switch is a shaft-driven movable stop and / or a pressure-sensitive switch.

7. An apparatus for deep purification of arsenic solution and preparation of high-purity arsenic oxide, characterized in that: The device includes a housing, in which a filter screen and a partition are spaced apart in the middle. The filter screen and the partition are respectively a purification tank and a reduction tank on both sides. The partition is provided with a liquid outlet, and a switch is provided in the liquid outlet to control the opening and closing of the liquid outlet.

8. The apparatus for deep purification of arsenic solution and preparation of high-purity arsenic oxide according to claim 7, characterized in that: The top cover of the chamber is provided with a liquid inlet, which is located above the purification tank and is used for the inlet of arsenic-containing solution. The top cover of the chamber is provided with a residual gas outlet, which is located above the reduction tank and is used to prevent the pressure inside the chamber from rising. The chamber is equipped with two independently controlled jacketed heat exchangers, wherein the first jacketed heat exchanger is used to control the temperature of the purification tank and the second jacketed heat exchanger is used to control the temperature of the reduction tank. The purification tank and the reduction tank are each equipped with a stirring paddle.

9. The apparatus for deep purification of arsenic solution and preparation of high-purity arsenic oxide according to claim 7, characterized in that: The housing is equipped with a filter screen scraper mechanism, which consists of a scraper, a filter screen, and a flow guide baffle. The scraper is used to scrape away accumulated dirt from the filter screen. The filter screen consists of an upper part with large holes and a lower part with micro holes. The upper part with large holes is the upper three-quarters of the filter screen, and the lower part with micro holes is the lower one-quarter of the filter screen. The mesh diameter of the upper part with large holes is 150-300 μm, and the mesh diameter of the lower part with micro holes is 0.2-0.5 μm. A flow guide baffle is attached to the side of the upper part of the filter screen near the reduction tank. The partition is provided with three parallel liquid outlets, each equipped with a switch to control the opening and closing of the liquid outlets. The lower end of each liquid outlet is located at 2 / 3 of the height of the partition. The switch is a shaft-driven movable stop and / or a pressure-sensitive switch.

10. The apparatus for deep purification of arsenic solution and preparation of high-purity arsenic oxide according to claim 7, characterized in that: A sedimentation base is fixedly connected to the bottom of the box body. The bottom part of the sedimentation base located in the purification tank and the reduction tank adopts a surface with an inclined angle and is provided with a mud guide channel with an inclined angle. The two sides of the sedimentation base are respectively provided with an AsSbO4 sedimentation mud outlet and an As2O3 product outlet. Both the AsSbO4 precipitate outlet and the As2O3 product outlet are equipped with sludge discharge valves; The bottom of the tank is also provided with a reducing agent pipe and an oxidizing agent pipe. The reducing agent pipe is used to transport the reducing agent into the reduction tank, and the oxidizing agent pipe is used to transport the oxidizing agent into the oxidation tank. The reducing agent pipeline, the oxidizing agent pipeline, and the precipitation base are formed together and arranged symmetrically. The purification tank is equipped with a temperature sensor and a pH meter, while the reduction tank is equipped with a temperature sensor and a liquid level monitor.

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