Waste acid purification and arsenic recovery system

Abstract

The utility model relates to a waste acid purification and arsenic recovery system which comprises a first-stage reactor and a first-stage FBL filter connected with the first-stage reactor, the first-stage FBL filter is sequentially connected with a second-stage reactor and a second-stage FBL filter, the second-stage FBL filter is sequentially connected with a neutralizing tank and a filter press, and the neutralizing tank and the filter press are sequentially connected. And the first-stage reactor and the second-stage reactor are both connected with the water glass tank and the sodium sulfide liquid preparation tank. According to the utility model, a two-stage arsenic and fluorine removal and neutralization fluorine removal purification system is adopted, sodium sulfide is added into the two-stage reactor for arsenic removal, water glass is added for fluorine removal, most of arsenic and fluorine can be removed, residual fluorine is further removed by a lime method, the arsenic and fluorine removal effect is obviously superior to that of the existing treatment system, the effluent can be ensured to stably reach the standard, and the energy consumption is reduced. And the effluent can reach the recycling standard.

Description

Technical Field

[0001] The utility model relates to the technical field of wastewater treatment, in particular to a system for purifying waste acid and recovering arsenic. Background Art

[0002] During the roasting and purification process of pyrite concentrate, dust, arsenic, fluorine, sulfur dioxide, sulfur trioxide and other components contained in the smelting flue gas are brought into the circulating acid through the circulating acid washing. After the circulating acid is recycled, the harmful components in it are continuously enriched. For this reason, it is necessary to conduct partial open circuit treatment on the circulating acid and add an equal amount of new water to reduce the concentration and dust content of the circulating acid. As a result, a large amount of high-arsenic-fluoride-containing acid wastewater is generated, which does not meet the emission and reuse standards. In addition, the fluorine in it will also corrode the purification equipment containing silica such as glass fiber reinforced plastic equipment, dry absorption tower porcelain rings and lining tiles, shortening their service life. Therefore, these wastewaters must be purified by de-arsenicing and de-fluorinating.

[0003] Existing waste acid treatment systems such as Figure 2 As shown, by combining a sulfidation reaction tank and a neutralization tank, a sulfide + lime neutralization method is adopted, firstly, sodium sulfide is used as a arsenic removal agent to carry out arsenic removal and defluorination reaction, and then lime milk is added for neutralization and defluorination treatment, and the obtained neutralized filtrate meets the discharge standards, and the filter residues are centrally piled up. However, the existing treatment system only uses a primary treatment for the removal of arsenic and fluorine, and there are cases where the removal effect is unstable and the effluent does not meet the standards. In addition, the arsenic-containing filter residues produced in the process are soluble and cannot be directly landfilled or recycled, requiring additional treatment. Therefore, the present application proposes a waste acid purification and arsenic recovery system to improve the arsenic and fluorine removal effect of waste acid, and to process and recycle the arsenic-containing filter residues. Utility Model Content

[0004] The utility model provides a system for purifying polluted acid and recovering arsenic.

[0005] The specific technical scheme of the utility model is: a waste acid purification and arsenic recovery system, comprising a primary reactor and a primary FBL filter connected thereto, the primary FBL filter is sequentially connected to a secondary reactor and a secondary FBL filter, the secondary FBL filter is sequentially connected to a neutralization tank and a filter press, and the primary reactor and the secondary reactor are both connected to a water glass tank and a sodium sulfide liquid preparation tank.

[0006] Further, preferably, both the primary FBL filter and the secondary FBL filter are connected to a flocculant tank.

[0007] Further, preferably, the primary FBL filter and the secondary FBL filter are both connected to the mud tank, the mud tank is sequentially connected to the primary high-pressure reactor and the primary filter, the primary filter is sequentially connected to the secondary high-pressure reactor and the secondary filter, the primary high-pressure reactor and the secondary high-pressure reactor are both connected to the copper sulfate solution tank, and the secondary filter is sequentially connected to the reduction tank, the centrifuge and the dryer.

[0008] The beneficial effects of the utility model are as follows: the utility model adopts a "two-stage arsenic removal and defluorination + neutralization defluorination" purification system, adds sodium sulfide to the two-stage reactor for arsenic removal, and adds water glass for defluorination, which can remove most of the arsenic and fluorine, and then further removes the remaining fluorine through the lime method. The arsenic and fluorine removal effect is significantly better than the existing treatment system, which can ensure that the effluent is stable and meets the standard, and the effluent can meet the reuse standard. At the same time, the "two-stage copper sulfate crystallization + one-stage reduction" arsenic recovery system is adopted to convert the arsenic in the arsenic-containing filter residue into arsenic trioxide with good quality, realize the efficient extraction and recovery of arsenic, and the process is stable, which can be applied to the recovery and treatment of arsenic-containing waste residues of different sources and properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 This is an equipment association diagram of a waste acid purification and arsenic recovery system of the utility model;

[0010] Figure 2 It is the equipment association diagram of the existing waste acid treatment system;

[0011] In the figure: 1-primary reactor, 2-primary FBL filter, 3-secondary reactor, 4-secondary FBL filter, 5-neutralization tank, 6-filter press, 7-water glass tank, 8-sodium sulfide preparation tank, 9-flocculant tank, 10-mud tank, 11-primary high-pressure reactor, 12-primary filter, 13-secondary high-pressure reactor, 14-secondary filter, 15-copper sulfate solution tank, 16-reduction tank, 17-centrifuge, 18-dryer. DETAILED DESCRIPTION

[0012] In order to make the technical problems and technical solutions solved by the utility model more clearly understood, the utility model is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the utility model and are not used to limit the utility model.

[0013] In the description of the present invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0014] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0015] like Figure 1 As shown, the waste acid purification and arsenic recovery system proposed in this embodiment replaces the existing waste acid treatment system (such as Figure 2 ) was adjusted from "one-stage arsenic removal + neutralization defluorination" to "two-stage arsenic removal + neutralization defluorination" to improve the arsenic removal and fluorination effect of waste acid, reduce harmful substances in waste acid, and ensure that the effluent meets the standards for reuse. At the same time, the "two-stage copper sulfate crystallization + one-stage reduction" arsenic recovery system was added to realize the recovery and utilization of arsenic in arsenic-containing filter residues.

[0016] The waste acid purification system in the system comprises a primary reactor 1 and a primary FBL filter 2 connected thereto, the primary FBL filter 2 is sequentially connected to a secondary reactor 3 and a secondary FBL filter 4, the secondary FBL filter 4 is sequentially connected to a neutralization tank 5 and a filter press 6, the primary reactor 1 and the secondary reactor 3 are both connected to a water glass tank 7 and a sodium sulfide liquid preparation tank 8, and the primary FBL filter 2 and the secondary FBL filter 4 are both connected to a flocculant tank 9.

[0017] The waste acid purification system can remove most of the arsenic and fluorine by adding sodium sulfide to the two-stage reactor for arsenic removal and water glass for fluorine removal, and then further remove the remaining fluorine through the lime method. The arsenic and fluorine removal effect is significantly better than the existing treatment system, which can ensure that the effluent is stable and meets the standards, and the effluent can meet the reuse standards. Among them, water glass, as an inorganic polymer material, has strong chemical stability and will not produce secondary pollution. Water glass reacts quickly with fluoride ions in wastewater, and the fluorine removal rate is better than the fluorine removal rate of lime milk, and the fluorine removal effect is stable. In addition, the system replaces the traditional filter press with an FBL filter, which can improve the filtration efficiency and filtration effect. Particles with a particle size of 0.1μm or more can be filtered, which is much better than the filter press. The FBL filter also has the advantages of large processing capacity, small footprint, high degree of automation (automatic backwashing can be realized, continuous liquid inlet and continuous liquid outlet), and stable effluent.

[0018] The arsenic recovery system in the system includes a mud tank 10, a primary FBL filter 2 and a secondary FBL filter 4 are both connected to the mud tank 10, the mud tank 10 is sequentially connected to a primary high-pressure reactor 11 and a primary filter 12, the primary filter 12 is sequentially connected to a secondary high-pressure reactor 13 and a secondary filter 14, the primary high-pressure reactor 11 and the secondary high-pressure reactor 13 are both connected to a copper sulfate solution tank 15, and the secondary filter 14 is sequentially connected to a reduction tank 16, a centrifuge 17 and a dryer 18.

[0019] The arsenic recovery system recovers arsenic from the arsenic-containing filter residue produced by the purification of waste acid through a two-stage high-pressure reactor and a first-stage reduction. It first undergoes a copper sulfate crystallization process to obtain arsenic acid or arsenous acid with higher purity, and then obtains arsenic trioxide with better quality through a reduction reaction, thereby achieving efficient extraction and recovery of arsenic. The process is stable and can be applied to the recovery and treatment of arsenic-containing waste residues from different sources and properties.

[0020] The above system is used for waste acid purification and arsenic recovery. The specific treatment process is as follows:

[0021] (1) The collected acid wastewater is pumped into the primary reactor 1 through a pressure pump, and calcium sulfide solution and water glass are added to carry out arsenic removal and defluorination reactions:

[0022] ①Na2S+H2SO4→H2S↑+Na2SO4

[0023] ②3H2S+2HAsO2→As2S3↓+4H2O

[0024] ③Na2SiO3+2HF→H2SiO3+2NaF

[0025] The reaction obtains arsenic-fluorine-containing slurry, which is input into the primary FBL filter 2 through a pipeline for filtration. In order to improve the filtration effect, a flocculant can be added to the primary FBL filter 2 to obtain a primary arsenic-containing filter residue and a primary filtrate.

[0026] (2) The primary filtrate is transferred to the secondary reactor 3, and the calcium sulfide solution and water glass are added again to carry out arsenic removal and defluorination reaction. The slurry obtained by the reaction is input into the secondary FBL filter 4 through a pipeline for filtration. In order to improve the filtration effect, a flocculant can be added to the secondary FBL filter 4 to obtain a secondary arsenic-containing filter residue and a secondary filtrate.

[0027] (3) The secondary filtrate is transferred to the neutralization tank 5 for neutralization with the added lime milk. The treated slurry passes through the filter press 6 to form a small amount of neutralization filter cake and neutralization filtrate. The neutralization filtrate enters the recovery system for recycling.

[0028] (4) The obtained first-stage arsenic-containing filter residue and the second-stage arsenic-containing filter residue are transferred to the slurry tank 10 for mixing, and then transferred to the first-stage high-pressure reactor 11 to react with the added copper sulfate solution at a temperature of about 65-70°C: As2S3+3CuSO4+4H2O→HAsO2+3CuS↓+3H2SO4. The reactants are separated through the first-stage filter 12 to form copper sulfide precipitate and As-containing 3+ filtrate.

[0029] (5) As 3+ The filtrate is transferred to the secondary high-pressure reactor 13, and the copper sulfate solution is added and air or oxygen is introduced at a temperature of about 80°C for oxidation reaction: 2HAsO2+O2+2H2O→2H3AsO4. The reactants are separated by the secondary filter 14 to form copper sulfide precipitate and As-containing 5+ filtrate;

[0030] (6) As 5+ The filtrate is transferred to the reduction tank 16, and SO2 or acid production tail gas is introduced for reduction reaction: H3AsO4+SO2→HAsO2+H2SO4, and then cooled and crystallized: HAsO2→As2S3+H2O, and then filtered and dried by the centrifuge 17 and the dryer 18 to obtain arsenic trioxide.

[0031] The treatment effect of the treated wastewater is shown in Table 1:

[0032] Table 1: Comparison of data before and after wastewater treatment

[0033] Test items pH Asmg / L Fmg / L Before wastewater treatment 1.4 1733 1600 After the original system wastewater treatment 6.2 0.47 8.9 New system wastewater treatment 7.3 0.01 0.9 Emission standards 6-9 0.5 10

[0034] The arsenic recovery of arsenic-containing filter residue is shown in Table 2:

[0035] Table 2: Arsenic recovery data of arsenic-containing filter residues

[0036] Test items As content% Before recovery of arsenic-containing residue 18 After recovery of arsenic-containing residue 0.02 Recovery rate 99.89

[0037] As shown in Table 1, the system can effectively treat the acid wastewater, and the effluent index after treatment is significantly better than that of the original treatment system, which can not only ensure that the effluent is stable and up to standard, but also realize the recycling of effluent. As shown in Table 2, the recovery rate of arsenic-containing filter residue in the system reaches 99.89%, with good recovery effect, and no secondary pollution will be generated in the process, which meets the regulations on comprehensive utilization of resources.

[0038] The present invention is described in detail above through specific and preferred embodiments, but those skilled in the art should understand that the present invention is not limited to the embodiments described above, and any modifications, equivalent substitutions, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A system for purifying polluted acid and recovering arsenic, characterized in that: The invention comprises a primary reactor (1) and a primary FBL filter (2) connected thereto, wherein the primary FBL filter (2) is sequentially connected to a secondary reactor (3) and a secondary FBL filter (4), wherein the secondary FBL filter (4) is sequentially connected to a neutralization tank (5) and a filter press (6), and the primary reactor (1) and the secondary reactor (3) are both connected to a water glass tank (7) and a sodium sulfide liquid preparation tank (8).

2. A system for purifying polluted acid and recovering arsenic according to claim 1, characterized in that: The primary FBL filter (2) and the secondary FBL filter (4) are both connected to a flocculant tank (9).

3. A system for purifying polluted acid and recovering arsenic according to claim 1, characterized in that: The primary FBL filter (2) and the secondary FBL filter (4) are both connected to a mud tank (10), the mud tank (10) is connected in sequence to a primary high-pressure reactor (11) and a primary filter (12), the primary filter (12) is connected in sequence to a secondary high-pressure reactor (13) and a secondary filter (14), the primary high-pressure reactor (11) and the secondary high-pressure reactor (13) are both connected to a copper sulfate solution tank (15), and the secondary filter (14) is connected in sequence to a reduction tank (16), a centrifuge (17) and a dryer (18).

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