A steel dust sludge filtrate purifier and its preparation method and application

Abstract

The invention discloses a steel dust filtrate purifier and a preparation method and application thereof, and relates to the technical field of steel dust filtrate treatment. The steel dust filtrate purifier of the invention comprises an agent A and an agent B; the agent A comprises the following chemical raw materials by mass: 10 parts of sodium bicarbonate and 5 to 30 parts of sodium carbonate; the agent B comprises the following chemical raw materials by mass: 10 parts of slow-release oxidant, 100 to 300 parts of flocculant, and 1.5 to 2.5 parts of anti-scaling dispersant; the slow-release oxidant comprises the following preparation raw materials by mass: 10 parts of potassium ferrate and 0.5 to 3 parts of polyvinyl acetate; the flocculant is a ternary polymer of dimethyldiallylammonium chloride-acrylamide-methacryloyloxyethyltrimethylammonium chloride. The steel dust filtrate purifier has high metal ion precipitation efficiency and fast speed.

Description

Technical Field

[0001] The invention belongs to the technical field of steel dust sludge filtrate treatment, and in particular is a steel dust sludge filtrate purifier and a preparation method and application thereof. Background Art

[0002] In the steel production process, the dust or sludge collected by the dust removal equipment contains a variety of heavy metal elements, such as lead, cadmium, thallium, etc. The discharge of the treated steel dust sludge filtrate needs to meet the "Steel Industry Wastewater Discharge Standard" (GB 13456-2012). In the purification treatment of traditional processes, the purification process usually adopts a step-by-step precipitation method. By adjusting the pH value of the solution, the elements such as lead, zinc, iron, calcium, and magnesium are successively precipitated to achieve step-by-step removal. However, this method has some disadvantages, such as requiring a large amount of investment, complex production process, many process control points, and large wastewater treatment volume. In addition, the rapid oxidation of the oxidant may lead to uneven floc formation, affect the sedimentation rate and removal efficiency, and cause floc residues. At the same time, too fast oxidation rate will also lead to excessive iron ions in the steel dust sludge filtrate, increase the burden of subsequent treatment, and fail to effectively remove thallium ions.

[0003] In view of these problems, the present invention proposes a steel dust sludge filtrate purifier. This agent utilizes the overlapped range of precipitation pH conditions between elements and the oxidation characteristics of potassium ferrate to efficiently remove impurities such as zinc, iron, calcium, magnesium, and thallium from the steel dust sludge water washing filtrate at one time. This method simplifies the production process, reduces the steps of slag-liquid separation and slag washing, thereby reducing the amount of wastewater generated in the production process and improving the treatment efficiency. Summary of the invention

[0004] The present invention overcomes at least one of the above technical problems, and thus provides a steel dust sludge filtrate purifier and a preparation method and application thereof. The method has high metal removal efficiency and less residue; the method is simple and convenient, low in cost and suitable for industrial production.

[0005] The present invention solves the above technical problems through the following technical solutions.

[0006] A steel dust sludge filtrate purifier, comprising agent A and agent B;

[0007] The agent A comprises the following chemical raw materials in parts by weight: 10 parts of sodium bicarbonate and 5 to 30 parts of sodium carbonate; preferably, it comprises 10 parts of sodium bicarbonate and 10 to 30 parts of sodium carbonate;

[0008] The agent B comprises the following chemical raw materials by weight: 10 parts of slow-release oxidant, 100-300 parts of flocculant, and 1.5-2.5 parts of anti-scaling dispersant; preferably, it comprises 10 parts of slow-release oxidant, 100-220 parts of flocculant, and 1.8-2.3 parts of anti-scaling dispersant;

[0009] The slow-release oxidant comprises the following raw materials by weight: 10 parts potassium ferrate and 1 to 3 parts polyvinyl acetate; preferably 10 parts potassium ferrate and 0.8 to 2.3 parts polyvinyl acetate. The present invention uses polyvinyl acetate-coated potassium ferrate as a slow-release oxidant to solve the problem of excessive oxidation of potassium ferrate in the traditional flocculation process, resulting in uneven flocs. Specifically, potassium ferrate can convert Tl + Oxidized to Tl 3+ , promoting the precipitation of thallium ions, but at the same time it will also oxidize ferrous ions into ferric ions. If the oxidation rate is too fast, too many iron ions will be produced, affecting the flocculation effect. The slow-release oxidant can not only control the oxidation rate of potassium ferrate to avoid excessive generation of iron ions, but also promote the precipitation of metal hydroxides to form suspended matter and tiny particles by virtue of its film-forming and adhesive properties, thereby enhancing the flocculation efficiency. And because ferrous ions are easier to precipitate than ferric ions, the use of slow-release oxidants ensures the stability of the oxidation process and reduces the additional burden caused by excessive iron ions in subsequent treatments.

[0010] The flocculant is a ternary polymer of dimethyldiallylammonium chloride (DMDAAC, CAS No.: 7398-69-8)-acrylamide (AM, CAS No.: 79-06-1)-methacryloyloxyethyltrimethylammonium chloride (DMC, CAS No.: 5039-78-1), and its structural unit is:

[0011] ;

[0012] 1000≤x≤15000, 1000≤y≤15000, 1000≤z≤15000;

[0013] The Mw of the flocculant is 6-8 million.

[0014] In the present invention, the flocculant is a terpolymer of dimethyldiallylammonium chloride-acrylamide-methacryloyloxyethyltrimethylammonium chloride (DMDAAC-AM-DMC), wherein DMDAAC is a cationic polymer monomer with good water solubility and stability, and can also provide adsorption bridging function for the flocculant. The copolymerization of DMDAAC and AM can form a high molecular weight cationic polymer, and the addition of DMC further enhances the cationic properties of the copolymer, so that it exhibits better flocculation performance in water treatment.

[0015] In the present invention, 1000≤x≤15000, 1000≤y≤15000, 1000≤z≤15000; preferably 7000≤x≤13500, 7000≤y≤13500, 7000≤z≤13500.

[0016] In the present invention, the mass ratio of the agent A to the agent B is 100:0.75-1.65, preferably 100:0.95-1.50.

[0017] In the present invention, the Mw of the flocculant is 6.8 to 7.6 million. Generally, the higher the molecular weight, the longer the dissolution time and the greater the viscosity. Therefore, it is believed that the larger the molecular weight, the more obvious the flocculation effect. However, if the molecular weight of the cationic polymer is too large, all the active points on the surface of the suspended particles will be adsorbed and surrounded by the polymer, making bridging difficult, and even decoagulation may occur, resulting in a decrease in the flocculation effect.

[0018] In the present invention, the viscosity of the flocculant is 5200-6800 cPa·s.

[0019] In the present invention, the cationic charge density of the flocculant is 18.8-27.3 meq / g, preferably 20.2-26.9 meq / g. The charge density of the cationic polymer is also a major factor affecting its flocculation ability.

[0020] In the present invention, the scale inhibitor and dispersant is a phosphorus-containing scale inhibitor and dispersant, preferably DP6615, DP6661 or DP6663.

[0021] In the present invention, the steel dust sludge filtrate contains the following elements in mass concentration: 1-3 g / L Fe, 1-3 g / L Zn, 0.1-0.5 g / L Cd, and 0.1-1 g / L Tl.

[0022] In the present invention, the steel dust sludge filtrate further comprises the following elements in mass concentration: 1-2 g / L Mg, 15-25 g / L Ca.

[0023] In the present invention, the light transmittance of the steel dust sludge filtrate is 47% to 54%.

[0024] In the present invention, the COD of the steel dust sludge filtrate is 0.1 g / L to 2 g / L.

[0025] The present invention provides a method for preparing a steel dust sludge filtrate purifier, comprising the following steps:

[0026] S1. Preparation of a slow-release oxidant: coating polyvinyl acetate and potassium ferrate by emulsification;

[0027] S2. Preparation of Agent A: Mix the raw materials for preparing Agent A in the desired ratio;

[0028] S3. Preparation of Agent B: Grind and mix the raw materials for preparation of Agent B according to the above ratio to obtain Agent B.

[0029] In the present invention, the process of the emulsification method is as follows: polyvinyl acetate is pre-emulsified first, and then an emulsifier and potassium ferrate are added for emulsification.

[0030] In the present invention, the pre-emulsification method is to mix polyvinyl acetate in water;

[0031] In the present invention, the emulsifier is sodium dodecyl sulfate;

[0032] In the present invention, the ratio of polyvinyl acetate: potassium ferrate: sodium dodecyl sulfate is 10:3-5:0.5-0.7, preferably 10:3.4-4.5:0.5-0.7, by weight.

[0033] In the present invention, the emulsification temperature is 70-80°C, preferably 75-80°C.

[0034] In the present invention, the emulsification time is 3 to 5 hours, preferably 4 hours.

[0035] In the present invention, the post-processing step after emulsification is drying.

[0036] The present invention also provides the use of a steel dust sludge filtrate purifier in steel dust sludge filtrate, comprising the following steps:

[0037] Step 1: First, add agent A to the steel dust sludge filtrate and mix until the pH reaches 9-11;

[0038] Step 2: Add agent B, stir and filter.

[0039] In the present invention, the addition ratio of the steel dust sludge filtrate purifier to the steel dust sludge filtrate is 0.01-0.05%.

[0040] In the present invention, the steel dust sludge filtrate purifier is added in every 10m 3 The treatment time of steel dust sludge filtrate is 15~38min.

[0041] In the present invention, the steel dust filtrate purifier has a zinc removal rate of ≥99.2%, an iron removal rate of ≥99.2%, a thallium removal rate of ≥99.0%, and a cadmium removal rate of ≥99.8% in the steel dust filtrate; preferably, the zinc removal rate is 99.27%~99.57%, the iron removal rate is 99.20%~99.57%, the thallium removal rate is 99.03%~99.58%, and the cadmium removal rate is 99.81%~99.92%.

[0042] In the present invention, the steel dust sludge filtrate purifier has a COD removal rate of ≥93.3% in the steel dust sludge filtrate, and preferably, the COD removal rate is 93.30% to 94.24%.

[0043] In the present invention, the steel dust filtrate purifier can also remove magnesium and calcium elements in the steel dust filtrate.

[0044] Furthermore, the steel dust filtrate purifier has a magnesium removal rate of ≥99.5% and a calcium removal rate of ≥99.8% in the steel dust filtrate.

[0045] In the present invention, the transparency of the steel dust sludge filtrate treated with the steel dust sludge filtrate purifier is 87% to 94%.

[0046] On the basis of being in accordance with the common sense in the art, the above-mentioned preferred conditions can be arbitrarily combined to obtain the preferred embodiments of the present invention.

[0047] Compared with the prior art, the present invention has the following beneficial effects:

[0048] 1. The slow-release oxidant selected in the present invention effectively controls the oxidation rate of potassium ferrate, solves the problem of uneven floccules caused by excessively fast oxidation rate in the traditional flocculation process, promotes the precipitation of thallium ions, and avoids the excessive generation of iron ions. In addition, the moldability and adhesion of the slow-release oxidant are conducive to the precipitation of metal hydroxides, thereby improving the flocculation efficiency.

[0049] 2. In order to further improve the flocculation performance, the cationic polymer of the present invention: the structure of the DMDAAC-AM-DMC ternary polymer provides good water solubility and stability, and at the same time has an adsorption bridging function to enhance the flocculation performance.

[0050] 3. Combining the above two components, the steel dust filtrate purifier of the present invention has high efficiency and fast speed in precipitating metal ions; the steel dust filtrate purifier has a removal rate of ≥99.2% for zinc, ≥99.2% for iron, ≥99.0% for thallium, ≥99.8% for cadmium, and ≥93.3% for COD in steel dust filtrate; in addition, the removal rate of magnesium is ≥99.5% and the removal rate of calcium is ≥99.8%. DETAILED DESCRIPTION

[0051] In order to facilitate the understanding of the present invention, the present invention will be described more comprehensively and carefully in combination with preferred embodiments below, but the protection scope of the present invention is not limited to the following specific embodiments.

[0052] Unless otherwise defined, all professional terms used below have the same meanings as those generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0053] The flocculant was purchased from Xinyong Biology. The preparation process of the flocculant is as follows (APS is ammonium persulfate):

[0054] The scale inhibitors and dispersants were purchased from Fumiao Technology with product numbers DP6615, DP6661 and DP6663.

[0055] Example 1

[0056] 1. The steel dust sludge filtrate purifier of this embodiment includes:

[0057] Agent A: 10 parts sodium bicarbonate and 20 parts sodium carbonate;

[0058] Agent B: 10 parts of slow-release oxidant, 120 parts of flocculant, 2.3 parts of anti-scaling dispersant (brand: DP6615);

[0059] The mass ratio of agent A to agent B is 100:1.32.

[0060] In this example, the flocculant has an Mw of 6.8 million (the raw material molar ratio of DMDAAC-AM-DMC is 1:1:1), a viscosity of 5200 cPa·s, and a cationic charge density of 24.8 meq / g;

[0061] 2. The preparation method of the steel dust sludge filtrate purifier of this embodiment is as follows:

[0062] S1. Preparation of slow-release oxidant: first pre-emulsify polyvinyl acetate (Mw 500,000) in water, then add emulsifiers sodium dodecyl sulfate and potassium ferrate and emulsify at 75°C for 4 hours, then dry the water to obtain a slow-release oxidant; wherein, by mass, polyvinyl acetate: potassium ferrate: sodium dodecyl sulfate = 10:3.6:0.6.

[0063] S2. Preparation of Agent A: Mix the raw materials for preparing Agent A according to the above-mentioned ratio of this embodiment.

[0064] S3. Preparation of Agent B: Grind and mix the raw materials for preparing Agent B according to the above-mentioned ratio of this embodiment to obtain Agent B.

[0065] 3. The application of the steel dust sludge filtrate purifier of this embodiment in the steel dust sludge filtrate is as follows:

[0066] Step 1: Add Agent A to the steel dust sludge filtrate and mix until the pH reaches 9.5;

[0067] Step 2: Add agent B and stir for 30 minutes at a stirring speed of 25r / min, then filter.

[0068] The addition ratio of the steel dust filtrate purifier in the steel dust filtrate of this embodiment is 0.048 wt %.

[0069] The light transmittance of the steel dust sludge filtrate after being treated with the steel dust sludge filtrate purifier of this embodiment is 87%.

[0070] Example 2

[0071] The difference between this embodiment and embodiment 1 is that:

[0072] The steel dust sludge filtrate purifier of this embodiment includes:

[0073] Agent A: 10 parts sodium bicarbonate and 30 parts sodium carbonate;

[0074] Agent B: 10 parts of slow-release oxidant, 180 parts of flocculant, 1.8 parts of anti-scaling dispersant (brand: DP6663);

[0075] The mass ratio of agent A to agent B is 100:1.27.

[0076] The light transmittance of the steel dust sludge filtrate after being treated with the steel dust sludge filtrate purifier of this embodiment is 91%.

[0077] Example 3

[0078] The difference between this embodiment and embodiment 1 is that:

[0079] The preparation method of the steel dust sludge filtrate purifier of this embodiment is as follows:

[0080] First, polyvinyl acetate (Mw 300,000) is pre-emulsified in water, and then emulsifiers sodium dodecyl sulfate and potassium ferrate are added and emulsified at 80°C for 3 hours. The water is then dried to obtain a slow-release oxidant; wherein, by mass, polyvinyl acetate: potassium ferrate: sodium dodecyl sulfate = 10:4.5:0.6.

[0081] The light transmittance of the steel dust sludge filtrate after being treated with the steel dust sludge filtrate purifier of this embodiment is 89%.

[0082] Example 4

[0083] The difference between this embodiment and embodiment 1 is that:

[0084] The application of the steel dust sludge filtrate purifier in the steel dust sludge filtrate of this embodiment is as follows:

[0085] Step 1: Add Agent A to the steel dust sludge filtrate and mix until the pH reaches 10;

[0086] Step 2: Add agent B and stir for 25 minutes at a stirring speed of 20r / min, then filter.

[0087] The addition ratio of the steel dust sludge filtrate purifier in the steel dust sludge filtrate of this embodiment is 0.040%.

[0088] The light transmittance of the steel dust sludge filtrate after being treated with the steel dust sludge filtrate purifier of this embodiment is 94%.

[0089] Comparative Example 1

[0090] The difference between this comparative example and Example 1 is:

[0091] The flocculant used in this comparative example is a binary polymer of dimethyldiallylammonium chloride-acrylamide;

[0092] The Mw of the flocculant was 7.5 million (the raw material molar ratio of DMDAAC-AM-DMC was 1:1:1), the viscosity was 1200 cPa·s, and the cationic charge density was 6.8 meq / g.

[0093] The light transmittance of the steel dust sludge filtrate after being treated with the steel dust sludge filtrate purifier of this comparative example is 81%.

[0094] Comparative Example 2

[0095] The difference between this comparative example and Example 1 is:

[0096] The flocculant used in this comparative example is zwitterionic polyacrylamide (brand: Xiens);

[0097] The Mw of the flocculant is 18 million.

[0098] The light transmittance of the steel dust sludge filtrate after being treated with the steel dust sludge filtrate purifier of this comparative example is 69%.

[0099] Comparative Example 3

[0100] The difference between this comparative example and Example 1 is:

[0101] This comparative example uses potassium ferrate as an oxidant instead of a slow-release oxidant.

[0102] The light transmittance of the steel dust sludge filtrate after being treated with the steel dust sludge filtrate purifier of this comparative example is 74%.

[0103] Comparative Example 4

[0104] The difference between this comparative example and Example 1 is:

[0105] Agent B: 10 parts of slow-release oxidant, 100 parts of flocculant, 2.3 parts of anti-scaling dispersant (brand: DP6615).

[0106] The light transmittance of the steel dust sludge filtrate after being treated with the steel dust sludge filtrate purifier of this comparative example is 77%.

[0107] Comparative Example 5

[0108] The difference between this comparative example and Example 1 is:

[0109] The preparation method of the steel dust sludge filtrate purifier of this comparative example is as follows:

[0110] S1. In the process of preparing the slow-release oxidant, the weight ratio of polyvinyl acetate: potassium ferrate: sodium dodecyl sulfate is 10:6.4:0.7.

[0111] The light transmittance of the steel dust sludge filtrate after being treated with the steel dust sludge filtrate purifier of this comparative example is 75%.

[0112] Comparative Example 6

[0113] The difference between this comparative example and Example 1 is:

[0114] The application of the steel dust sludge filtrate purifier of this comparative example in the steel dust sludge filtrate is as follows:

[0115] Step 1: Add Agent A to the steel dust sludge filtrate and mix until the pH reaches 8;

[0116] Step 2: Add agent B and stir for 30 minutes at a stirring speed of 20r / min, then filter.

[0117] The addition ratio of the steel dust sludge filtrate purifier in this comparative example to the steel dust sludge filtrate is 0.06%.

[0118] The light transmittance of the steel dust sludge filtrate after being treated with the steel dust sludge filtrate purifier of this comparative example is 82%.

[0119] Effect Example

[0120] The steel dust sludge filtrate purifiers prepared in the above comparative examples and embodiments are effective in treating steel dust sludge filtrate. The contents of various substances are determined using plasma emission spectrometry.

[0121] The contents of various substances in the steel dust sludge filtrate are shown in Table 1.

[0122]

[0123] The effects of the steel dust sludge filtrate purifier prepared in the above comparative examples and embodiments on treating various ions are shown in Table 2.

[0124]

[0125] It can be seen from Table 2 that, relative to the flocculant in Example 1, the flocculant in Comparative Example 1 has a higher viscosity and a lower charge density, which is usually due to the insufficient number of functional groups resulting in a low charge density, which is not conducive to charge neutralization and further affects the removal effect of impurity ions.

[0126] The flocculant used in Comparative Example 2 is a high molecular weight amphoteric polyacrylamide. It is possible that the network structure formed by the high molecular weight amphoteric polyacrylamide in water is more complex and compact, resulting in reduced solubility, reducing the effective capture and bridging effect on suspended particles, thereby affecting its effective contact and adsorption capacity with suspended particles in water.

[0127] Comparative Example 3 uses potassium ferrate as an oxidant. Potassium ferrate has a fast oxidation rate, which causes ferrous ions to be oxidized into ferric ions, increasing the difficulty of sedimentation. + Fully oxidized without being completely removed.

[0128] In Comparative Example 4, a small amount of flocculant was added to Agent B, so the flocculation effect was poor, resulting in a low removal rate of some ions.

[0129] The amount of polyethyl acetate coated in the slow-release oxidant of Comparative Example 5 is insufficient, which not only leads to a high oxidation rate, but also affects the adhesion of the surface of the slow-release oxidant, thus being unfavorable for the flocculation of the sediment.

[0130] In the application method of Comparative Example 6, under the condition of weak alkalinity, even if the amount of purifier added is increased appropriately, the sedimentation efficiency is low.

[0131] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods. The specific embodiments described above further describe the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, 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 steel dust sludge filtrate purifier, characterized in that: Includes dose A and dose B; The agent A comprises the following chemical raw materials by weight: 10 parts of sodium bicarbonate and 5 to 30 parts of sodium carbonate; The agent B comprises the following chemical raw materials by weight: 10 parts of a slow-release oxidant, 100 to 300 parts of a flocculant, and 1.5 to 2.5 parts of a scale inhibitor and dispersant; The slow-release oxidant comprises the following raw materials in parts by weight: 10 parts of potassium ferrate and 0.5 to 3 parts of polyvinyl acetate; The flocculant is a ternary polymer of dimethyldiallylammonium chloride-acrylamide-methacryloyloxyethyltrimethylammonium chloride, and its structural unit is ； 1000≤x≤15000, 1000≤y≤15000, 1000≤z≤15000.

2. The steel dust sludge filtrate purifier according to claim 1, characterized in that: The mass ratio of the A agent to the B agent is 100:0.75~1.

65.

3. The steel dust sludge filtrate purifier according to claim 1, characterized in that: Meet at least one of the following conditions ①~②: ① The viscosity of the flocculant is 5200~6800 cPa·s; ② The cationic charge density of the flocculant is 18.8~27.3 meq / g.

4. The steel dust sludge filtrate purifier according to claim 1, characterized in that: The scale inhibitor and dispersant is a phosphorus-containing scale inhibitor and dispersant.

5. The steel dust sludge filtrate purifier according to claim 1, characterized in that: The steel dust sludge filtrate satisfies at least one of the following conditions ① to ④: ① The steel dust sludge filtrate contains the following mass concentration elements: 1~3 g / L Zn, 1~3 g / L Fe, 0.1~1 g / LTl, 0.1~0.5 g / L Cd; ② The steel dust sludge filtrate also contains the following mass concentration elements: 1-2 g / L Mg, 15-25 g / L Ca; ③ The light transmittance of the steel dust sludge filtrate is 47% to 54%; ④ The COD of the steel dust sludge filtrate is 0.1~2 g / L.

6. The method for preparing the steel dust sludge filtrate purifier according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1. Preparation of a slow-release oxidant: coating polyvinyl acetate and potassium ferrate by emulsification; S2. Preparation of Agent A: Mix the raw materials for preparing Agent A in the desired ratio; S3. Preparation of Agent B: Grind and mix the raw materials for preparation of Agent B according to the above ratio to obtain Agent B.

7. The method for preparing the steel dust sludge filtrate purifier according to claim 6, characterized in that: The process of the emulsification method is as follows: polyvinyl acetate is pre-emulsified first, and then an emulsifier and potassium ferrate are added for emulsification.

8. The method for preparing the steel dust sludge filtrate purifier according to claim 7, characterized in that: Meet at least one of the following conditions ①~⑥: ① The pre-emulsification method is to mix polyvinyl acetate in water; ② The emulsifier is sodium dodecyl sulfate; ③ In terms of mass, the polyvinyl acetate: potassium ferrate: sodium dodecyl sulfate = 10: 3-5: 0.5-0.7; ④ The emulsification temperature is 70-80°C; ⑤ The emulsification time is 3 to 5 hours; ⑥ The post-processing step after the emulsification is drying.

9. Use of the steel dust sludge filtrate purifier according to any one of claims 1 to 5 in steel dust sludge filtrate, characterized in that: The following steps are involved: Step 1: First, add agent A to the steel dust sludge filtrate and mix until the pH reaches 9-11; Step 2: Add agent B, stir and filter.

10. Use of the steel dust sludge filtrate purifier according to claim 9 in steel dust sludge filtrate, characterized in that: Meet at least one of the following conditions ①~⑥: ① The addition ratio of the steel dust sludge filtrate purifier to the steel dust sludge filtrate is 0.01-0.05 wt %; ② The steel dust sludge filtrate purifier is added every 10m 3 The treatment time of steel dust sludge filtrate is 15~38min; ③ The removal rate of the steel dust sludge filtrate purifier for zinc in the steel dust sludge filtrate is ≥99.2%, the removal rate of iron is ≥99.2%, the removal rate of thallium is ≥99.0%, and the removal rate of cadmium is ≥99.8%; ④ The removal rate of COD in the steel dust sludge filtrate by the steel dust sludge filtrate purifier is ≥ 93.3%; ⑤ The removal rate of magnesium in the steel dust sludge filtrate by the steel dust sludge purifier is ≥99.5%, and the removal rate of calcium in the steel dust sludge filtrate is ≥99.8%; ⑥ The transparency of the steel dust sludge filtrate treated with the steel dust sludge filtrate purifier is 87% to 94%.

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