Iron-carbon filler, preparation method and application thereof

Abstract

The application provides an iron-carbon filler and a preparation method and application thereof. The preparation raw material of the iron-carbon filler comprises 30-60 parts of iron-carbon catalytic raw material, 25-50 parts of river channel sediment and 5-15 parts of tailing waste rock. The iron coarse concentrate and the tailing waste rock are obtained by treating iron tailings; the iron-carbon catalytic raw material is obtained by pyrolyzing a mixture comprising straw and the iron coarse concentrate, in the pyrolyzing process, the organic carbon in the straw is reduced to active carbon, the high-valence metal in the iron coarse concentrate is reduced to zero-valence metal, the active carbon can uniformly load the reduced metal, and the iron-carbon catalytic raw material is obtained. The iron-carbon filler is prepared from the iron-carbon catalytic raw material, the tailing waste rock and the river channel sediment, the cost is reduced, the river channel sediment, the iron tailings and the straw resources are developed with high value, the waste is changed into treasure, and the iron-carbon filler is applied in the water treatment field, waste is treated by waste, and economic benefits are created.

Description

Technical Field

[0001] This invention belongs to the field of water treatment, specifically relating to an iron-carbon filler, its preparation method, and its application. Background Technology

[0002] Iron-carbon microelectrolysis technology, as a pretreatment technology for high-concentration organic wastewater, is currently widely used in wastewater treatment fields such as electroplating, printing, mining, pharmaceuticals, and pesticides. In the iron-carbon microelectrolysis reactor, Fe, with its reduction potential, acts as the anode, and carbon as the cathode, spontaneously forming numerous micro-current batteries. Accompanied by a series of physical and chemical reactions, this process degrades large organic molecules into smaller molecules, improving the biodegradability of the wastewater. However, the iron-carbon filler prepared using different raw materials and methods significantly impacts its application effectiveness and cost. Therefore, reducing raw material costs and improving its application efficiency are crucial for its practical application.

[0003] Riverbed sediment, as an important component of rivers, exchanges substances with river water during river development. When excessive pollutants enter the river, it causes sediment pollution. This polluted sediment then affects water quality through secondary pollution of the overlying water. Endogenous pollution caused by sediment is a key factor contributing to black and odorous water bodies. Therefore, dredging polluted sediment is an indispensable part of the treatment of black and odorous water bodies. Traditional methods for disposing of polluted sediment mainly include landfill and incineration. Landfilling requires a large amount of land, wasting land resources, while incineration requires less land but has higher maintenance costs. Therefore, sediment resource utilization technology has received widespread attention from scholars. Currently, domestic sediment resource utilization methods mainly focus on building material utilization. By solidifying dredged sediment and adding a certain amount of concrete and other building matrices, products that can replace traditional building materials are prepared. However, the advantages of the manufactured building materials compared to traditional building materials are not significant. Therefore, it is necessary to develop a high-value utilization product for sediment.

[0004] In recent years, the amount of straw generated from crops has gradually increased. Currently, returning straw to the field is the most important form of straw resource utilization, but it still faces problems such as a long decomposition cycle, insect egg residue, and limited ability to promote soil fertility. At the same time, the resource utilization of straw still needs to consider its economic value, that is, how to utilize straw in a high-value manner.

[0005] Iron tailings, as a major type of industrial solid waste, are mainly composed of metallic and non-metallic minerals, characterized by fine particle size, diverse types, and large stockpiles. Therefore, exploring efficient, large-scale, and environmentally friendly comprehensive utilization methods for iron tailings has become an urgent need for iron ore enterprises and the mining industry. Currently, extracting valuable metals from iron tailings is a common resource utilization method; however, the complex and diverse composition of iron tailings from different regions makes it difficult to meet the needs of single-metal recovery. Summary of the Invention

[0006] In view of this, the purpose of this invention is to provide an iron-carbon filler, its preparation method, and its application. This iron-carbon filler uses riverbed sediment, iron tailings, and straw as main raw materials, reducing raw material costs. Simultaneously, it can also be used in water treatment, turning waste into resources.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides an iron-carbon filler, the raw materials for which, by weight, comprise:

[0009] 30-60 parts of iron-carbon catalytic feedstock;

[0010] 25-50 parts of riverbed sediment;

[0011] 5-15 portions of tailings waste rock;

[0012] The iron-carbon catalytic feedstock is obtained by pyrolysis of a mixture including straw and iron concentrate;

[0013] The iron concentrate and tailings waste rock are obtained by processing iron tailings.

[0014] Preferably, the raw materials for preparation further include 3 to 6 parts of a fluxing agent.

[0015] Preferably, the fluxing agent is selected from boric acid.

[0016] Preferably, the mass ratio of straw to iron concentrate is 2:1 to 5:1.

[0017] Preferably, the pyrolysis is carried out under anaerobic or hypoxic conditions.

[0018] Preferably, the iron concentrate and tailings waste rock are obtained by crushing and flotation of iron tailings.

[0019] Preferably, the riverbed sediment is pre-washed, and the washing agent is a biosurfactant.

[0020] Secondly, the present invention provides a method for preparing the above-mentioned iron-carbon filler, comprising the following steps:

[0021] The iron-carbon filler blank, which includes iron-carbon catalytic raw materials, riverbed sediment, tailings waste rock and optional flux, is dried and calcined to obtain iron-carbon filler.

[0022] The iron-carbon catalytic feedstock is obtained by pyrolysis of a mixture including straw and iron concentrate;

[0023] The iron concentrate and tailings waste rock are obtained by processing iron tailings.

[0024] Preferably, the calcination is carried out under anaerobic or hypoxic conditions.

[0025] Preferably, the roasting is carried out according to the following procedure:

[0026] Preheating stage: Heat to 300-450℃ and hold for 10-30 minutes;

[0027] Calcination stage: Heat to 900-1000℃ and hold for 25-40 minutes;

[0028] The heating rate for roasting is 5–15 °C / min.

[0029] Preferably, the pyrolysis temperature is 850–1000°C.

[0030] Thirdly, the present invention provides an application of the above-mentioned iron-carbon packing material in wastewater treatment.

[0031] Preferably, the ratio of the iron-carbon packing material to the wastewater is (10-20) g: 100 mL.

[0032] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0033] This invention provides an iron-carbon packing material, the raw materials of which include 30-60 parts of iron-carbon catalytic raw material, 25-50 parts of riverbed sediment, and 5-15 parts of tailings waste rock. The iron concentrate and tailings waste rock are obtained by processing iron tailings; the iron-carbon catalytic raw material is obtained by pyrolyzing a mixture including straw and iron concentrate. During this pyrolysis process, the organic carbon in the straw is reduced to activated carbon, and the high-valence metals in the iron concentrate are reduced to zero-valence metals, thus allowing the activated carbon to uniformly load the reduced metals, resulting in the iron-carbon catalytic raw material. This invention combines the iron-carbon catalytic raw material with tailings waste rock and riverbed sediment to prepare a composite sediment-based iron-carbon packing material, which not only reduces costs but also allows for the high-value development of riverbed sediment, iron tailings, and straw resources, turning "waste" into "treasure." Its application in the water treatment field, using waste to treat waste, can create certain economic benefits.

[0034] This invention simulates wastewater using a norfloxacin aqueous solution with pH=3 and a norfloxacin concentration of 100 mg / L. The iron-carbon packing material was then placed in the wastewater. Results showed that after 120 minutes of treatment, the average removal rate of norfloxacin in the wastewater reached over 69%, and the COD removal rate reached over 19%. Therefore, the iron-carbon packing material provided by this invention exhibits excellent removal performance in wastewater treatment. Attached Figure Description

[0035] Figure 1 Diagram showing the phase composition of riverbed sediment;

[0036] Figure 2The diagram shows the phase composition of iron-carbon catalytic feedstocks with different mass ratios.

[0037] Figure 3 A comparison of norfloxacin removal rates of iron-carbon packing materials with different mass ratios.

[0038] Figure 4 A comparison of norfloxacin removal rates of the prepared iron-carbon fillers at different calcination temperatures;

[0039] Figure 5 This is a phase composition diagram of the iron-carbon filler obtained in Example 3;

[0040] Figure 6 Here is a SEM image of the iron-carbon filler obtained in Example 3;

[0041] Figure 6 The 'a' in the figure corresponds to 100μm. Figure 6 The 'b' in the figure corresponds to 30μm. Figure 6 The 'c' in the text corresponds to 10 μm. Figure 6 The d in the figure corresponds to 10 μm. Detailed Implementation

[0042] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0043] Addressing the issue of high-value utilization of riverbed sediment, iron tailings, and straw in existing technologies, this invention proposes to utilize the iron concentrate and tailings waste rock obtained after crushing and flotation of iron tailings separately. First, straw is mixed evenly with the separated iron concentrate and then subjected to a pyrolysis reaction. High-temperature pyrolysis reduces various metal elements in the tailings concentrate, and the straw is pyrolyzed into activated carbon. This activated carbon uniformly loads the reduced metal components from the iron concentrate, thus preparing an iron-carbon catalytic raw material. Then, the flotation tailings waste rock, riverbed sediment, and iron-carbon catalytic raw material are used to prepare an iron-carbon filler. In this invention, while pyrolyzing straw to generate activated carbon, the pyrolysis temperature is fully utilized to reduce the iron concentrate, and simultaneously, it is uniformly loaded onto the framework formed by the riverbed sediment and tailings waste rock under high-temperature conditions. Not only does it reduce costs, but it also allows for the high-value development of bottom sediment, iron tailings, and straw resources, turning "waste" into "treasure." It produces composite bottom sediment-based iron-carbon filler composed of straw, iron tailings, and river bottom sediment, which is then applied in the field of water treatment, using waste to treat waste and creating certain economic benefits.

[0044] Specifically, the present invention provides an iron-carbon filler, the raw materials for which, by weight, comprise:

[0045] 30-60 parts of iron-carbon catalytic feedstock;

[0046] 25-50 parts of riverbed sediment;

[0047] 5-15 portions of tailings waste rock.

[0048] To make it easier to understand, each raw material will be explained in more detail below.

[0049] The present invention does not impose any particular restrictions on the source of the bottom sediment. In some embodiments of the present invention, the source of the river bottom sediment is the Ershibu River in Hefei.

[0050] In some preferred embodiments of the present invention, the riverbed sediment is pre-washed to remove heavy metal ions, preventing the release of heavy metal ions into the water body and causing secondary pollution during subsequent use. The washing agent is preferably a biosurfactant, more preferably a 3% rhamnolipin solution with pH = 7. The liquid-to-solid ratio of the biosurfactant to the riverbed sediment is 2:1 to 4:1, preferably 3:1.

[0051] In some preferred embodiments of the present invention, after the washing is completed, the product is dried at 100-110°C, preferably 105°C, then ground, crushed and sieved for later use.

[0052] In this invention, iron tailings are preferably processed to obtain iron concentrate and tailings waste rock, which are used as raw materials for preparing iron-carbon filler. This invention does not impose any particular restrictions on the source of the iron tailings; in some embodiments, the iron tailings originate from the Ma'anshan mine.

[0053] In some embodiments of the present invention, it is preferable to crush and flotate the iron tailings to obtain iron concentrate and tailings waste rock. Specifically, the following steps are included:

[0054] After crushing and screening, the iron tailings are floated in an XFG type hanging trough flotation machine. Each flotation is carried out with 18-20g of iron tailings, 180-200mL of deionized water, and the mixture is prepared for 1-2 minutes. The pH value is then adjusted to 8-9 with NaOH solution and stirred for 2-4 minutes. Then, 90-110mg / L of sodium oleate and starch or citric acid (40-50mg / L) are added sequentially and stirred for 2-5 minutes respectively. After 6 minutes of flotation, the iron crude concentrate and tailings waste rock are obtained (in this step, starch can be replaced with citric acid).

[0055] In the aforementioned flotation process, sodium oleate acts as a collector, making oxide minerals / salts containing calcium, magnesium, iron, aluminum, etc., hydrophobic and promoting their flotation. Starch (or citric acid) acts as an inhibitor, making gangue minerals (silicate gangue minerals, quartz) hydrophilic and preventing their flotation. This invention combines sodium oleate and starch (or citric acid), enabling the separation of metallic and non-metallic minerals and improving the efficiency of subsequent iron-carbon catalytic feedstock preparation.

[0056] According to the present invention, after obtaining the above-mentioned iron crude concentrate, it is preferable to pyrolyze the mixture of straw and iron crude concentrate to obtain an iron-carbon catalytic feedstock. The present invention does not limit the source of the straw; in some embodiments of the present invention, the straw originates from rural farmland in Lianyungang, Jiangsu Province.

[0057] In some embodiments of the present invention, it is preferred that straw and iron concentrate are mixed in a certain mass ratio of 2:1 to 5:1 (e.g., 2:1, 3:1, 4:1, 5:1) and then placed in a tubular furnace for pyrolysis under anaerobic or oxygen-deficient conditions. This ensures that the high-valent metals in the straw and iron concentrate are effectively reduced to activated carbon and zero-valent metals, respectively. The pyrolysis temperature is 850–1000°C (e.g., 850°C, 875°C, 900°C, 925°C, 950°C, 975°C, or 1000°C), and the pyrolysis time is 0.5–5 hours (e.g., 0.5 hours, 1 hour, 2 hours, 3 hours, 4 hours, or 5 hours). After the pyrolysis is completed, an iron-carbon catalytic feedstock is obtained.

[0058] The aforementioned oxygen-free or oxygen-deficient conditions can be provided by a vacuum tube furnace or a tube furnace and muffle furnace that introduces an inert gas (such as nitrogen).

[0059] This invention utilizes the combined pyrolysis of straw and iron ore concentrate. This process not only reduces the straw to activated carbon components, but the reducing gases generated during pyrolysis also reduce iron oxides and iron-containing minerals in the iron concentrate to zero-valent iron at a certain temperature. After sufficient reaction and extraction of zero-valent iron and activated carbon, this material can replace traditional commercial iron powder and activated carbon in the preparation of iron-carbon fillers. This technology not only reduces costs but also fully utilizes the components of straw and iron ore, truly turning waste into treasure.

[0060] According to the present invention, after obtaining the iron-carbon catalytic raw material, preferably 30-60 parts of the iron-carbon catalytic raw material, 25-50 parts of riverbed sediment, and 5-15 parts of tailings waste rock are used as raw materials to prepare iron-carbon filler. The "30-60 parts" in the 30-60 parts of the iron-carbon catalytic raw material can be 30, 35, 40, 45, 50, or 60 parts, etc.; the "25-50 parts" in the 25-50 parts of riverbed sediment can be 25, 30, 35, 40, 45, or 50 parts, etc.; and the "5-15 parts" in the 5-15 parts of tailings waste rock can be 5, 8, 10, 12, or 15 parts, etc.

[0061] In some preferred embodiments of the present invention, the raw materials for preparation further include 3 to 6 parts of a fluxing agent, specifically 3, 4, 5, or 6 parts. The fluxing agent is preferably boric acid. The addition of the fluxing agent not only reduces the temperature required for the filler to be fired and formed, saving energy, but also helps the substances in the riverbed sediment to react fully, generating more skeletal structures and improving the overall stability of the filler.

[0062] The present invention also provides a method for preparing the above-mentioned iron-carbon filler, comprising the following steps:

[0063] The iron-carbon filler blank, which includes iron-carbon catalytic raw materials, riverbed sediment, tailings waste rock and optional flux, is dried and calcined to obtain iron-carbon filler.

[0064] The preparation or selection of the iron-carbon catalytic raw materials, riverbed sediment, tailings waste rock, and optional fluxing agents are as described above and will not be repeated here.

[0065] In this invention, the iron-carbon filler blank is obtained by mixing iron-carbon catalytic raw materials, riverbed sediment, tailings waste rock and optional fluxing agent, and an appropriate amount of water can also be added, and the resulting blank is granular.

[0066] Then, according to the present invention, the iron-carbon filler blank is dried at 100-110°C for 0.5-5 hours, preferably at 100°C for 2 hours.

[0067] After drying, calcination is performed. In this invention, the calcination is preferably carried out under oxygen-free or oxygen-deficient conditions, such as in a vacuum tube furnace or a tube furnace and muffle furnace purged with an inert gas (such as nitrogen), to create an inert atmosphere and prevent zero-valent metals, especially zero-valent iron, from being oxidized to valuable metals in an oxygen-containing environment.

[0068] In some embodiments of the present invention, the calcination is performed according to the following procedure:

[0069] Preheating stage: Heat to 300-450℃ and hold for 10-30 minutes;

[0070] Calcination stage: Heat to 900-1000℃ and hold for 25-40 minutes.

[0071] For example, the procedure can be followed as follows:

[0072] Program 1:

[0073] Preheating stage: Heat to 400℃ and hold for 30 minutes;

[0074] Calcination stage: Heat to 900℃ and hold for 30 minutes.

[0075] Program 2:

[0076] Preheating stage: Heat to 400℃ and hold for 30 minutes;

[0077] Calcination stage: Heat to 925℃ and hold for 30 minutes.

[0078] Procedure 3:

[0079] Preheating stage: Heat to 400℃ and hold for 30 minutes;

[0080] Calcination stage: Heat to 950℃ and hold for 30 minutes.

[0081] Procedure Four:

[0082] Preheating stage: Heat to 400℃ and hold for 30 minutes;

[0083] Calcination stage: Heat to 975℃ and hold for 30 minutes.

[0084] In the roasting process of this invention, the material is first preheated at 300-450°C and then roasted at 900-1000°C. This is because the preheating stage can decompose the organic matter in the riverbed sediment and generate a certain amount of gas, creating a certain amount of open pores. This prevents the rapid vaporization of moisture at high temperatures from causing the filler to burst, while also reducing the heat load in the high-temperature section and lowering energy consumption.

[0085] The roasting process described in this invention is not limited to the methods listed above; the temperature and time can be adjusted within the range described above.

[0086] In this invention, the heating rate of the above-mentioned calcination is 5 to 15°C / min, such as 5°C / min, 8°C / min, 10°C / min, 12°C / min or 15°C / min, etc.

[0087] After calcination, the iron-carbon filler is obtained.

[0088] Furthermore, this invention provides an application of the aforementioned iron-carbon packing material in wastewater treatment. In this application, the ratio of the iron-carbon packing material to wastewater is (10-20) g:100 mL, such as 10 g:100 mL, 12 g:100 mL, 15 g:100 mL, 18 g:100 mL, or 20 g:100 mL, etc.

[0089] In some embodiments of the present invention, taking the treatment of norfloxacin-simulated wastewater as an example, the specific steps are as follows:

[0090] Add 100 mL of simulated norfloxacin wastewater with pH = 3 and a norfloxacin concentration of 100 mg / L to a beaker. Add 15 g of iron-carbon packing material to the simulated wastewater and react for 120 min under an aeration rate of 1 L / min. Take a sample every 20 min during the reaction, add 0.1 mol / L NaOH solution to remove excess ferrous ions from the solution, and then filter through a 0.22 μm filter membrane to detect the concentrations of norfloxacin and COD.

[0091] The results showed that after 120 minutes of treatment, the average removal rate of norfloxacin in the wastewater reached over 69%, and the COD removal rate reached over 19%. This demonstrates that the iron-carbon packing material provided by this invention has excellent removal effects in the field of wastewater treatment.

[0092] In summary, this invention provides an iron-carbon filler, its preparation method, and its application. This method has the following advantages: ① It removes heavy metals from riverbed sediment: using biosurfactants to remove heavy metal ions from the sediment, preventing the release of heavy metal ions into the water body during subsequent use and causing secondary pollution; ② It utilizes riverbed sediment components in a comprehensive and high-value manner: the skeletal structure generated by the sediment at high temperatures serves as a carrier for loading iron and carbon sources, not only reducing the preparation cost of the iron-carbon filler but also making the iron and carbon sources more evenly distributed on the carrier, while improving the filler's anti-caking ability; the effective utilization of the sediment not only saves on sediment treatment and disposal costs, but high-temperature calcination also solidifies the heavy metals and other substances that were not leached out in the sediment within the carrier, avoiding secondary pollution. Simultaneously, the organic matter in the sediment acts as a pore-forming agent for the filler, eliminating the need for additional pore-forming agents in the preparation of the iron-carbon filler, fully utilizing the organic and inorganic components in the sediment, and truly achieving valuable and comprehensive utilization of the sediment; ③ It addresses the issue of iron tailings... Effective pretreatment of the ore: Iron concentrate (primarily iron) and silica-based waste rock are separated from the tailings through flotation. Further processing improves tailings utilization efficiency and reduces energy consumption. Furthermore, quartz and silicate minerals in the waste rock can form a framework under high temperatures. Adding boric acid as a flux not only lowers the required firing temperature for the filler, saving energy, but also helps the substances in the sediment react fully, generating more framework structures and improving the overall stability of the filler. Co-roasting straw with iron concentrate not only reduces the straw to activated carbon components, but the reducing gases generated during roasting can also reduce iron oxides and iron-containing minerals in the iron concentrate to zero-valent iron at a certain temperature. After fully reacting and extracting zero-valent iron and activated carbon, this filler replaces traditional commercial iron powder and activated carbon in the preparation of iron-carbon filler. This not only reduces costs but also fully utilizes the straw and iron concentrate components, truly turning waste into treasure. Furthermore, the iron-carbon filler can be applied in water treatment, treating waste with waste and creating economic benefits.

[0093] To further illustrate the present invention, the following embodiments are provided for detailed description. The riverbed sediment used in the following embodiments of the present invention originated from the Ershibu River in Hefei, the iron tailings originated from the Ma'anshan Mine in Anhui, and the straw originated from rural farmland in Lianyungang, Jiangsu.

[0094] Example 1

[0095] This embodiment provides an iron-carbon filler, the preparation method of which is as follows:

[0096] (1) Washing, drying and crushing of riverbed sediment: The riverbed sediment was washed for 1 hour with a biosurfactant (pH=7, 3% rhamnolipin solution, liquid-solid ratio 3:1) to remove harmful heavy metals from the sediment. Then it was dried at 105℃, ground, crushed and sieved.

[0097] (2) Crushing and flotation of iron tailings: After crushing the iron tailings, they are screened and flotation is carried out in an XFG type hanging trough flotation machine. Each flotation is carried out with 18g of iron tailings, 180mL of deionized water, and 1min of slurry preparation. The pH value is then adjusted to 9 and stirred for 2min. Then, sodium oleate (100mg / L) and starch (40mg / L) are added in sequence and stirred for 2min each. After 6min of flotation, iron crude concentrate and tailings waste rock are obtained.

[0098] (3) Preparation of iron-carbon catalytic feedstock: Straw and iron concentrate were mixed in mass ratios of 2:1, 3:1, 4:1 and 5:1 and then placed in a tube furnace, nitrogen was continuously introduced and pyrolyzed at 900℃ for 1 hour;

[0099] (4) Preparation of sediment-based iron-carbon filler blank: The iron-carbon catalytic raw material obtained in step (3) is mixed with the river sediment obtained in step (1), the tailings waste rock obtained in step (2) and boric acid in a mass ratio of 28:15:5:2 to obtain a mixture and add an appropriate amount of water (accounting for 40% of the solid mass in the mixture) to form granular sediment-based iron-carbon filler blank, and dry it at 105℃ for 2h.

[0100] (5) Firing of composite bottom mud-based iron-carbon filler: The blank obtained in step (4) is placed in a tube furnace, and nitrogen is continuously introduced at a heating rate of 10℃ / min. After preheating to a certain temperature of 400℃ for 15min, the temperature is further increased to 900℃ and the filler is calcined for a certain time of 30min to obtain iron-carbon filler.

[0101] The phase composition of the above-mentioned crushed riverbed sediment is as follows: Figure 1 As shown, the phase composition of the iron-carbon catalytic feedstock obtained by pyrolysis of straw and iron concentrate at mass ratios of 2:1, 3:1, and 4:1 is as follows. Figure 2 As shown.

[0102] Treatment of Norfloxacin-simulated wastewater: Add 100 mL of Norfloxacin-simulated wastewater with pH = 3 and a Norfloxacin concentration of 100 mg / L to a beaker. Add 15 g of the iron-carbon packing material prepared in step (5) to the simulated wastewater and react for 120 min under an aeration intensity of 1 L / min. Simulated wastewater concentration and COD test: Take a sample every 20 min during the reaction process, add 0.1 mol / L NaOH solution to remove excess ferrous ions from the solution, and then filter through a 0.22 μm filter membrane. Detect the concentrations of Norfloxacin and COD, and calculate the removal rates of Norfloxacin and COD.

[0103] Among them, the removal rate of norfloxacin (D), D(%) = (C0-C) / C0;

[0104] C0 and C represent the initial and residual concentrations of norfloxacin, respectively.

[0105] COD removal rate (R), R (%) = (COD0 - COD) / COD0;

[0106] COD0 and COD are the initial and residual concentrations of COD, respectively.

[0107] Test results are as follows Figure 3 As shown in Table 1:

[0108] Table 1

[0109]

[0110] Example 2

[0111] This embodiment provides an iron-carbon filler, the preparation method of which is as follows:

[0112] (1) Washing, drying and crushing of riverbed sediment: The riverbed sediment was washed for 1 hour with a biosurfactant (pH=7, 3% rhamnolipin solution, liquid-solid ratio 3:1) to remove harmful heavy metals from the sediment. Then it was dried at 105℃, ground, crushed and sieved.

[0113] (2) Crushing and flotation of iron tailings: After crushing the iron tailings, they are screened and flotation is carried out in an XFG type hanging trough flotation machine. Each flotation is carried out with 18g of iron tailings, 180mL of deionized water, and 1min of slurry preparation. The pH value is then adjusted to 9 and stirred for 2min. Then, sodium oleate (100mg / L) and starch (40mg / L) are added in sequence and stirred for 2min each. After 6min of flotation, iron crude concentrate and tailings waste rock are obtained.

[0114] (3) Preparation of iron-carbon catalytic feedstock: Straw and iron concentrate were mixed at a mass ratio of 4:1 and placed in a tube furnace. Nitrogen gas was continuously introduced and pyrolyzed at 900℃ for 1 hour.

[0115] (4) Preparation of sediment-based iron-carbon filler blank: The iron-carbon catalytic raw material obtained in step (3) is mixed with the river sediment obtained in step (1), the tailings waste rock obtained in step (2) and boric acid in a mass ratio of 28:15:5:2 to obtain a mixture and add an appropriate amount of water (accounting for 40% of the solid mass in the mixture) to form granular sediment-based iron-carbon filler blank, and dry it at 105℃ for 2h.

[0116] (5) Firing of composite bottom mud-based iron-carbon filler: The blank obtained in step (4) is placed in a tube furnace, and nitrogen is continuously introduced while the temperature is raised to a certain temperature of 400℃ for 15 minutes. Then, the temperature is raised to 900℃, 925℃, 950℃ or 975℃ and the filler is calcined for a certain time of 30 minutes to obtain iron-carbon filler.

[0117] The test for treating norfloxacin-simulated wastewater is based on Example 1.

[0118] Test results are as follows Figure 4 As shown in Table 2:

[0119] Table 2

[0120]

[0121] Example 3

[0122] This embodiment provides an iron-carbon filler, the preparation method of which is as follows:

[0123] (1) Washing, drying and crushing of riverbed sediment: The riverbed sediment was washed for 1 hour with a biosurfactant (pH=7, 3% rhamnolipin solution, liquid-solid ratio 3:1) to remove harmful heavy metals from the sediment. Then it was dried at 105℃, ground, crushed and sieved.

[0124] (2) Crushing and flotation of iron tailings: After crushing the iron tailings, they are screened and flotation is carried out in an XFG type hanging trough flotation machine. Each flotation is carried out with 18g of iron tailings, 180mL of deionized water, and 1min of slurry preparation. The pH value is then adjusted to 8 and stirred for 2min. Then, sodium oleate (110mg / L) and citric acid (50mg / L) are added in sequence and stirred for 2min each. After 6min of flotation, iron crude concentrate and tailings waste rock are obtained.

[0125] (3) Preparation of iron-carbon catalytic feedstock: Straw and iron concentrate were mixed at a mass ratio of 3:1 and placed in a tube furnace. Nitrogen gas was continuously introduced and pyrolyzed at 950℃ for 2 hours.

[0126] (4) Preparation of sediment-based iron-carbon filler blank: The iron-carbon catalytic raw material obtained in step (3) is mixed with the river sediment obtained in step (1), the tailings waste rock obtained in step (2) and boric acid in a mass ratio of 30:11:3:3 to obtain a mixture. A suitable amount of water (accounting for 40% of the solid mass in the mixture) is added to form granular sediment-based iron-carbon filler blank, and dried at 105℃ for 2h.

[0127] (5) Firing of composite bottom mud-based iron-carbon filler: The blank obtained in step (4) is placed in a tube furnace, and nitrogen is continuously introduced at a heating rate of 10℃ / min. After preheating to a certain temperature of 425℃ for 18min, the temperature is further increased to 950℃ and the filler is calcined for a certain time of 35min to obtain iron-carbon filler.

[0128] XRD tests were performed on the obtained iron-carbon filler, and the results are as follows: Figure 5 As shown, the riverbed sediment and tailings waste rock formed a robust framework mainly composed of anorthite, mullite, and fir olivine under high temperature, providing a certain mechanical strength for the composite sediment-based iron-carbon filler. At the same time, it exhibits a large zero-valent iron diffraction peak, indicating that the filler contains a large amount of zero-valent iron.

[0129] SEM tests were performed on the obtained iron-carbon filler, and the results are as follows: Figure 6 As shown, after high-temperature calcination, a robust framework of blocks and flakes is formed, with zero-valent iron distributed relatively evenly on the framework. The abundant pores inside the filler provide conditions for the occurrence of micro-electrolysis reactions.

[0130] The test for treating norfloxacin-simulated wastewater is based on Example 1.

[0131] Calculations show that the average removal rate of norfloxacin was 82.93%, and the COD removal rate was 33.90%.

[0132] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An iron-carbon filler, characterized in that, The raw materials for preparation, by weight, include: 30-60 parts of iron-carbon catalyst feedstock; 25-50 parts of riverbed sediment; 5-15 portions of tailings waste rock; 3-6 parts of fluxing agent; The iron-carbon catalytic feedstock is obtained by pyrolysis of a mixture including straw and iron concentrate; The iron crude concentrate and tailings waste rock are obtained by crushing and flotation of iron tailings. The preparation method of the iron-carbon filler includes the following steps: Iron-carbon filler blanks, which include iron-carbon catalytic raw materials, riverbed sediment, tailings waste rock, and fluxing agent, are dried and calcined to obtain iron-carbon filler.

2. The iron-carbon packing according to claim 1, characterized in that, The fluxing agent is selected from boric acid.

3. The iron-carbon packing according to claim 1 or 2, characterized in that, The mass ratio of straw to iron concentrate is 2:1 to 5:1; The pyrolysis is carried out under anaerobic or hypoxic conditions.

4. The iron-carbon packing according to claim 1, characterized in that, The riverbed sediment is pre-washed using a biosurfactant.

5. A method for preparing iron-carbon filler as described in any one of claims 1 to 4, characterized in that, Includes the following steps: Iron-carbon filler blanks, which include iron-carbon catalytic raw materials, riverbed sediment, tailings waste rock, and fluxing agent, are dried and calcined to obtain iron-carbon filler.

6. The preparation method according to claim 5, characterized in that, The roasting is carried out under anaerobic or hypoxic conditions; The roasting is carried out according to the following procedure: Preheating stage: Heat to 300~450℃ and hold for 10~30 minutes; Calcination stage: Heat to 900~1000℃ and hold for 25~40 min; The heating rate for roasting is 5~15 ℃ / min.

7. The preparation method according to claim 5 or 6, characterized in that, The pyrolysis temperature is 850~1000℃.

8. The application of the iron-carbon packing material according to any one of claims 1 to 4 or the iron-carbon packing material prepared by the preparation method according to any one of claims 5 to 7 in wastewater treatment.

9. The application according to claim 8, characterized in that, The ratio of the iron-carbon packing material to the wastewater is (10~20) g: 100 mL.

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