Iron-carbon filler as well as preparation method and application thereof

Abstract

The invention provides an iron-carbon filler as well as a preparation method and application thereof. The iron-carbon filler is prepared from the following raw materials in parts by weight: 30-60 parts of an iron-carbon catalytic raw material, 25-50 parts of river sediment and 5-15 parts of tailing barren rock. Wherein the iron rough concentrate and the tailing barren rock are obtained after iron tailings are treated; the iron-carbon catalytic raw material is obtained by pyrolyzing a mixture comprising straw and iron rough concentrate, in the pyrolysis process, organic carbon in the straw is reduced into activated carbon, high-valence metal in the iron rough concentrate is reduced into zero-valence metal, the activated carbon can uniformly load the reduced metal, and the iron-carbon catalytic raw material is obtained. According to the invention, the iron-carbon catalytic raw material, the tailing waste rock and the river sediment are prepared into the composite sediment-based iron-carbon filler, so that the cost is reduced, the river sediment, the iron tailings and straw resources are developed with high value, wastes are turned into treasures, the composite sediment-based iron-carbon filler is applied to the field of water treatment, wastes are treated by wastes, and economic benefits are created.

Description

Technical Field

[0001] The invention belongs to the field of water treatment, and in particular relates to an iron-carbon filler and a preparation method and application thereof. Background Art

[0002] As a pretreatment technology for high-concentration organic wastewater, iron-carbon micro-electrolysis technology has been widely used in wastewater treatment fields such as electroplating, printing, mining, pharmaceuticals, and pesticides. In the iron-carbon micro-electrolysis reactor, Fe with a reduction potential serves as the anode and carbon serves as the cathode, spontaneously forming many microcurrent cells. Accompanied by a series of physical and chemical reactions, these cells degrade organic macromolecular pollutants into small molecules, improving the biodegradability of the wastewater. However, the different raw materials and preparation methods used to produce iron-carbon fillers have a significant impact on the application effect and cost. Therefore, reducing the cost of raw materials and improving their application efficiency are crucial for their practical application.

[0003] As a vital component of rivers, riverbed sediments exchange substances with river water during their development. When excessive pollutants enter a river, sediment pollution can occur. This contaminated sediment can then affect water quality through secondary pollution of the overlying water. Endogenous pollution caused by sediment is a key factor contributing to the black and odorous nature of water bodies. Therefore, dredging contaminated sediment is an essential component of the treatment of black and odorous water bodies. Traditional methods for disposing of contaminated sediments primarily include landfilling and incineration. Landfilling requires significant land use and wastes land resources, while incineration occupies less land but carries high maintenance costs. Therefore, sediment resource utilization technologies have garnered significant attention. Currently, domestic sediment resource utilization methods primarily focus on building material utilization. By solidifying dredged sediment and combining it with concrete and other building matrices, products are prepared that can replace traditional building materials. However, these resulting building materials offer limited advantages over traditional building materials, necessitating the development of high-value sediment utilization products.

[0004] In recent years, the amount of crop straw generated has gradually increased. Currently, returning straw to the field is the primary form of straw resource utilization, but it still faces challenges such as a long decomposition cycle, residual insect eggs, and limited ability to improve soil fertility. Furthermore, straw resource utilization must consider its economic value—that is, how to maximize its utilization.

[0005] Iron tailings, a major industrial solid waste, are primarily 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 a pressing need for iron ore companies and the mining industry. Currently, extracting valuable metals from iron tailings is a common resource utilization method, but the complex and diverse composition of iron tailings in different regions makes it difficult to meet the needs of a single metal recovery. Summary of the Invention

[0006] In view of this, the present invention aims to provide an iron-carbon filler and its preparation method and application. The iron-carbon filler is made of riverbed mud, iron tailings and straw as main raw materials, which reduces raw material costs and can also be used for water treatment, treating waste with waste.

[0007] To achieve this object, the present invention adopts the following technical solutions:

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

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

[0010] 25-50 parts of riverbed mud;

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

[0012] The iron-carbon catalytic raw material is obtained by pyrolyzing a mixture of straw and iron coarse concentrate;

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

[0014] Preferably, the preparation raw materials further include 3 to 6 parts of flux.

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

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

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

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

[0019] Preferably, the riverbed mud is washed in advance, and the washing agent is a biosurfactant.

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

[0021] Drying and calcining an iron-carbon filler blank comprising an iron-carbon catalytic raw material, riverbed mud, tailings waste rock, and an optional fluxing agent to obtain an iron-carbon filler;

[0022] The iron-carbon catalytic raw material is obtained by pyrolyzing a mixture of straw and iron coarse concentrate;

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

[0024] Preferably, the calcination is carried out under oxygen-free or oxygen-deficient conditions.

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

[0026] Preheating stage: heating to 300-450℃, keeping warm for 10-30 minutes;

[0027] Calcination stage: heating to 900-1000℃, keeping warm for 25-40min;

[0028] The heating rate of the calcination is 5-15°C / min.

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

[0030] In a third aspect, the present invention provides an application of the above-mentioned iron-carbon filler in wastewater treatment.

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

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] The present invention provides an iron-carbon filler, the raw materials for its preparation comprising 30-60 parts of an iron-carbon catalytic raw material, 25-50 parts of riverbed mud, and 5-15 parts of tailings waste rock. The iron ore concentrate and tailings waste rock are obtained by processing iron tailings; the iron-carbon catalytic raw material is obtained by pyrolyzing a mixture of straw and the iron ore concentrate. During the pyrolysis process, the organic carbon in the straw is reduced to activated carbon, and the high-valent metals in the iron ore concentrate are reduced to zero-valent metals, thereby uniformly loading the activated carbon with the reduced metals, thereby obtaining the iron-carbon catalytic raw material. The present invention combines the iron-carbon catalytic raw material with tailings waste rock and riverbed mud to prepare a composite mud-based iron-carbon filler. This not only reduces costs but also allows for the high-value development of riverbed mud, iron tailings, and straw resources, transforming them from "waste" into "treasures" and applying them in the field of water treatment to treat waste with waste, thereby creating certain economic benefits.

[0034] The present invention simulates wastewater with a norfloxacin aqueous solution having a pH of 3 and a norfloxacin concentration of 100 mg / L. The iron-carbon filler is placed in the wastewater. The results show that after 120 minutes of treatment, the average removal rate of norfloxacin in the wastewater can reach over 69%, and the COD removal rate can reach over 19%. This shows that the iron-carbon filler provided by the present invention has excellent removal effects in the wastewater field. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is the phase composition diagram of the riverbed mud;

[0036] Figure 2The phase composition diagram of iron-carbon catalytic raw materials with different mass ratios;

[0037] Figure 3 The figure is a comparison of norfloxacin removal rates of iron-carbon fillers prepared with iron-carbon catalytic raw materials of different mass ratios;

[0038] Figure 4 The comparison chart of norfloxacin removal rate of iron-carbon filler prepared at different calcination temperatures;

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

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

[0041] Figure 6 a in corresponds to 100 μm, Figure 6 b in the figure corresponds to 30 μm. Figure 6 The c in the figure corresponds to 10 μm. Figure 6 The d in the figure corresponds to 10 μm. DETAILED DESCRIPTION

[0042] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0043] In response to the problem of high-value utilization of riverbed mud, iron tailings, and straw in the existing technology, the present invention proposes to separately utilize the iron concentrate and tailings waste rock obtained after crushing and flotation of iron tailings. First, straw is mixed evenly with the iron concentrate obtained by sorting, and then subjected to a pyrolysis reaction. The various metal elements in the tailings concentrate are reduced by high temperature, and the straw is pyrolyzed into activated carbon. The activated carbon is evenly loaded with the reduced metal components in the iron concentrate to prepare an iron-carbon catalytic raw material; the flotation tailings waste rock, riverbed mud, and iron-carbon catalytic raw material are then used to prepare an iron-carbon filler. In the present invention, while pyrolyzing straw to produce activated carbon, the pyrolysis temperature is fully utilized to reduce the iron concentrate, and at the same time, it is evenly loaded onto the skeleton formed by the riverbed mud and tailings waste rock under high temperature conditions. It not only reduces costs, but also develops sludge, iron tailings and straw resources at high value, turning "waste" into "treasure", and making composite sludge-based iron-carbon fillers composed of straw, iron tailings and riverbed sludge, and applies them 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 preparing the filler include, by weight:

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

[0046] 25-50 parts of riverbed mud;

[0047] 5 to 15 parts of tailings waste rock.

[0048] For ease of understanding, each raw material is further described below.

[0049] The present invention has no particular limitation on the source of the bottom mud. In some embodiments of the present invention, the source of the riverbed mud is the Ershibu River in Hefei.

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

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

[0052] In the present invention, the iron tailings are preferably processed to obtain iron coarse concentrate and tailings waste rock as raw materials for preparing iron-carbon filler. The present invention has no particular limitation on the source of the iron tailings. In some embodiments of the present invention, the source of the iron tailings is Ma'anshan mine.

[0053] In some embodiments of the present invention, the iron tailings are preferably crushed and flotated to obtain the iron concentrate and tailings waste rock. Specifically, the process includes the following steps:

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

[0055] During the flotation process, sodium oleate acts as a collector, rendering oxide ores and salt minerals containing calcium, magnesium, iron, and aluminum hydrophobic, promoting their buoyancy. Starch (or citric acid) acts as an inhibitor, rendering gangue minerals (silicate gangue minerals, quartz) hydrophilic, preventing them from buoyancy. The present invention combines sodium oleate with starch (or citric acid) to separate metallic minerals from non-metallic minerals, improving the efficiency of subsequent preparation of iron-carbon catalyst feedstock.

[0056] According to the present invention, after obtaining the above-mentioned crude iron concentrate, the mixture of straw and crude iron concentrate is preferably pyrolyzed to obtain an iron-carbon catalytic raw material. The present invention does not limit the source of the straw. In some embodiments of the present invention, the straw is sourced from rural farmland in Lianyungang, Jiangsu.

[0057] In some embodiments of the present invention, straw and iron ore concentrate are preferably mixed in a certain mass ratio of 2:1 to 5:1, which may be 2:1, 3:1, 4:1, or 5:1, and then placed in a tubular furnace for pyrolysis under anaerobic or anoxic conditions to ensure that the high-valent metals in the straw and the iron ore concentrate are effectively reduced to activated carbon and zero-valent metals, respectively. The pyrolysis temperature is 850 to 1000° C., such as 850° C., 875° C., 900° C., 925° C., 950° C., 975° C., or 1000° C., and the pyrolysis time is 0.5 to 5 hours, such as 0.5 hours, 1 hour, 2 hours, 3 hours, 4 hours, or 5 hours. After the pyrolysis is completed, an iron-carbon catalytic raw material is obtained.

[0058] The above-mentioned oxygen-free or oxygen-deficient conditions can be provided by a vacuum tube furnace or a tube furnace and a muffle furnace into which an inert gas (such as nitrogen) is introduced.

[0059] This invention combines straw with raw iron ore concentrate for pyrolysis, reducing the straw to activated carbon. The reducing gases generated during the pyrolysis process can also, at a certain temperature, reduce the iron oxides and iron-containing minerals in the raw iron concentrate to zero-valent iron. After sufficient reaction, the zero-valent iron and activated carbon components are extracted. This can then be used to prepare iron-carbon fillers, replacing traditional commercial iron powder and activated carbon. This technology not only reduces costs but also fully utilizes both straw and iron ore, truly transforming waste into valuable resources.

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

[0061] In some preferred embodiments of the present invention, the raw materials further include 3 to 6 parts of a flux, specifically 3 parts, 4 parts, 5 parts, or 6 parts. The flux is preferably boric acid. The addition of the flux not only reduces the temperature required for sintering the filler, saving energy, but also helps the substances in the riverbed mud to fully react, forming more skeleton 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 comprising iron-carbon catalytic raw materials, riverbed mud, tailings waste rock and optional flux is dried and roasted to obtain the iron-carbon filler.

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

[0065] In the present invention, the iron-carbon filler blank is obtained by mixing iron-carbon catalytic raw materials, riverbed mud, tailings waste rock and an optional flux, and a proper amount of water can be added. The obtained blank is in granular form.

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

[0067] After drying, calcination is performed. In the present invention, calcination is preferably performed in the absence of oxygen or in the absence of oxygen, such as in a vacuum tube furnace or a tube furnace or muffle furnace filled with an inert gas (such as nitrogen) to create an inert atmosphere and prevent the zero-valent metal, particularly zero-valent iron, from being oxidized to a valuable metal in an oxygen environment.

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

[0069] Preheating stage: heating to 300-450℃, keeping warm for 10-30 minutes;

[0070] Calcination stage: heat to 900-1000℃ and keep warm for 25-40 minutes.

[0071] For example, the following procedure may be followed:

[0072] Procedure 1:

[0073] Preheating stage: heat to 400℃ and keep warm for 30 minutes;

[0074] Calcination stage: heat to 900℃ and keep warm for 30 minutes.

[0075] Procedure 2:

[0076] Preheating stage: heat to 400℃ and keep warm for 30 minutes;

[0077] Calcination stage: heat to 925℃ and keep warm for 30 minutes.

[0078] Procedure 3:

[0079] Preheating stage: heat to 400℃ and keep warm for 30 minutes;

[0080] Calcination stage: heat to 950℃ and keep warm for 30 minutes.

[0081] Procedure 4:

[0082] Preheating stage: heat to 400℃ and keep warm for 30 minutes;

[0083] Calcination stage: heat to 975℃ and keep warm for 30 minutes.

[0084] During the roasting process, the present invention is first preheated at 300-450°C and then fired at 900-1000°C. This is because the preheating stage can decompose organic matter in the riverbed mud and produce a certain amount of gas, generating a certain amount of open pores, which prevents the rapid vaporization of water at high temperature from causing the filler to burst, while reducing the heat load in the high-temperature section and lowering energy consumption.

[0085] The calcination procedure of the present invention is not limited to the above-mentioned methods, and the temperature and time can be adjusted within the above-mentioned ranges.

[0086] In the present invention, the heating rate of the 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.

[0087] After the roasting is completed, the iron-carbon filler can be obtained.

[0088] The present invention further provides an application of the iron-carbon filler in wastewater treatment, wherein the ratio of the iron-carbon filler 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.

[0089] In some embodiments of the present invention, taking the treatment of norfloxacin simulated wastewater as an example, specifically:

[0090] Add 100 mL of norfloxacin simulated wastewater with a pH of 3 and a norfloxacin concentration of 100 mg / L into a beaker, take 15 g of iron-carbon filler and put it into the simulated wastewater, and react for 120 minutes under an aeration intensity of 1 L / min; during the reaction, take a sample every 20 minutes, add 0.1 mol / L NaOH solution to remove excess ferrous ion interference in the solution, and then filter it through a 0.22 μm filter membrane to detect the norfloxacin and COD concentrations.

[0091] The results showed that after 120 minutes of treatment, the average removal rate of norfloxacin in the wastewater could reach more than 69%, and the COD removal rate could reach more than 19%. It can be seen that the iron-carbon filler provided by the present invention has an excellent removal effect in the field of wastewater.

[0092] In summary, the present invention provides an iron-carbon filler and a preparation method and application thereof, which has the following advantages: 1. Carrying out a certain heavy metal removal treatment on the riverbed mud: using biological surfactants to remove heavy metal ions in the mud, and preventing the release of heavy metal ions into the water body during subsequent use, thereby preventing secondary pollution; 2. Comprehensive and high value-added utilization of riverbed mud components: the skeleton structure generated by the mud at high temperature is used as a carrier to load iron source and carbon source, which not only reduces the preparation cost of the iron-carbon filler, but also makes the iron source and carbon source more evenly distributed on the carrier, while improving the filler's anti-caking ability; the effective utilization of the mud not only saves the mud treatment and disposal cost, but also the high-temperature roasting also solidifies the heavy metals and other substances that have not been eluted out of the mud in the carrier, avoiding secondary pollution, and at the same time, the organic matter in the mud is used as a filler pore-forming agent, so that the preparation of the iron-carbon filler does not require additional pore-forming agents, and fully utilizes the organic and inorganic components in the mud, truly realizing the valuable and comprehensive utilization of the mud; 3. 4. Effective pre-treatment of the ore: The flotation process separates the iron-based iron concentrate and the silicon oxide-based tailings waste rock in the tailings. Different processing methods are then performed on them, which improves the utilization efficiency of the tailings and reduces energy consumption. The quartz and silicate minerals in the tailings waste rock can also form a skeleton under high temperature conditions. 5. Adding boric acid as a fluxing agent: This not only reduces the temperature required for the filler to be sintered and formed, saving energy, but also helps the substances in the bottom mud to fully react, generate more skeleton structures, and improve the overall stability of the filler. 6. By co-roasting straw with the iron concentrate, not only is the straw reduced to an activated carbon component, but the reducing gas generated during the roasting process can also reduce the 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, the iron-carbon filler is prepared instead of traditional commercial iron powder and activated carbon. 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 to the field of water treatment, using waste to treat waste and creating certain economic benefits.

[0093] To further illustrate the present invention, the following examples are provided for detailed description. The riverbed mud used in the following examples was sourced from Ershibu River in Hefei, the iron tailings were sourced from the mines in Ma'anshan, Anhui, and the straw was sourced from rural fields in Lianyungang, Jiangsu.

[0094] Example 1

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

[0096] (1) Washing, drying, and crushing of riverbed mud: Use a biosurfactant (pH = 7, 3% rhamnolipid solution, liquid-to-solid ratio 3:1) to wash the riverbed mud for 1 hour to remove harmful heavy metals in the mud, then dry it at 105°C, grind it, crush it, and sieve it;

[0097] (2) Crushing and flotation of iron tailings: The iron tailings were crushed and sieved, and flotation was carried out in an XFG hanging trough flotation machine. 18 g of iron tailings were added to the flotation, 180 mL of deionized water was added and the slurry was adjusted for 1 min, the pH value was adjusted to 9 and stirred for 2 min, and then sodium oleate (100 mg / L) and starch (40 mg / L) were added in sequence, and stirred for 2 min respectively. After 6 min of flotation, the iron concentrate and tailings waste rock were obtained;

[0098] (3) Preparation of iron-carbon catalytic raw materials: straw and iron ore concentrate were mixed in a mass ratio of 2:1, 3:1, 4:1, and 5:1, placed in a tubular furnace, and pyrolyzed at 900 °C for 1 h while continuously introducing nitrogen;

[0099] (4) Preparation of sediment-based iron-carbon filler blank: The iron-carbon catalytic raw material prepared in step (3) is mixed with the riverbed mud 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 an appropriate amount of water (accounting for 40% of the solid mass in the mixture) is added to form a granular sediment-based iron-carbon filler blank, which is then dried at 105° C. for 2 h;

[0100] (5) Firing of composite bottom mud-based iron-carbon filler: The blank obtained in step (4) is placed in a tubular furnace, operated at a heating rate of 10°C / min and continuously introduced with nitrogen, the temperature is raised to a certain temperature of 400°C and preheated for 15 minutes, and then the temperature is continued to be raised to 900°C and the filler is roasted for a certain time of 30 minutes to obtain an iron-carbon filler.

[0101] The phase composition of the crushed riverbed mud is as follows: Figure 1 As shown in the figure, the phase composition of the iron-carbon catalytic raw material obtained by pyrolysis of straw and iron ore in a mass ratio of 2:1, 3:1, and 4:1 is as follows: Figure 2 shown.

[0102] Treatment of norfloxacin simulated wastewater: 100 mL of norfloxacin simulated wastewater (pH = 3, with a norfloxacin concentration of 100 mg / L) was added to a beaker. 15 g of the iron-carbon filler prepared in step (5) was added to the simulated wastewater. The mixture was reacted for 120 min at an aeration intensity of 1 L / min. Simulated wastewater concentration and COD testing: Samples were taken every 20 min during the reaction, and 0.1 mol / L NaOH solution was added to remove excess ferrous ion interference in the solution. The solution was then filtered through a 0.22 μm filter membrane, and the norfloxacin and COD concentrations were measured. The norfloxacin removal rate and COD removal rate were calculated.

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

[0104] C0 and C are the initial concentration and residual concentration of norfloxacin, respectively.

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

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

[0107] The 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, and the preparation method thereof is as follows:

[0112] (1) Washing, drying, and crushing of riverbed mud: Use a biosurfactant (pH = 7, 3% rhamnolipid solution, liquid-to-solid ratio 3:1) to wash the riverbed mud for 1 hour to remove harmful heavy metals in the mud, then dry it at 105°C, grind it, crush it, and sieve it;

[0113] (2) Crushing and flotation of iron tailings: The iron tailings were crushed and sieved, and flotation was carried out in an XFG hanging trough flotation machine. 18 g of iron tailings were added to the flotation, 180 mL of deionized water was added and the slurry was adjusted for 1 min, the pH value was adjusted to 9 and stirred for 2 min, and then sodium oleate (100 mg / L) and starch (40 mg / L) were added in sequence, and stirred for 2 min respectively. After 6 min of flotation, the iron concentrate and tailings waste rock were obtained;

[0114] (3) Preparation of iron-carbon catalytic raw materials: straw and iron ore concentrate were mixed in a mass ratio of 4:1 and placed in a tubular furnace. Nitrogen was continuously introduced and pyrolyzed at 900 °C for 1 h.

[0115] (4) Preparation of sediment-based iron-carbon filler blank: The iron-carbon catalytic raw material prepared in step (3) is mixed with the riverbed mud 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 an appropriate amount of water (accounting for 40% of the solid mass in the mixture) is added to form a granular sediment-based iron-carbon filler blank, which is then dried at 105° C. for 2 h;

[0116] (5) Firing of composite bottom mud-based iron-carbon filler: The blank obtained in step (4) is placed in a tubular furnace, operated at a heating rate of 10°C / min and continuously introduced with nitrogen, the temperature is raised to a certain temperature of 400°C and preheated for 15 minutes, and then the temperature is continued to be raised to 900°C, 925°C, 950°C or 975°C and the filler is roasted for a certain time of 30 minutes to obtain an iron-carbon filler.

[0117] Test Reference Example 1 for treating norfloxacin simulated wastewater.

[0118] The 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, and the preparation method thereof is as follows:

[0123] (1) Washing, drying, and crushing of riverbed mud: Use a biosurfactant (pH = 7, 3% rhamnolipid solution, liquid-to-solid ratio 3:1) to wash the riverbed mud for 1 hour to remove harmful heavy metals in the mud, then dry it at 105°C, grind it, crush it, and sieve it;

[0124] (2) Crushing and flotation of iron tailings: The iron tailings were crushed and sieved, and flotation was carried out in an XFG hanging trough flotation machine. 18 g of iron tailings were added to the flotation, 180 mL of deionized water was added and the slurry was adjusted for 1 min, the pH value was adjusted to 8 and stirred for 2 min, and then sodium oleate (110 mg / L) and citric acid (50 mg / L) were added in sequence, and stirred for 2 min respectively. After 6 min of flotation, the iron concentrate and tailings waste rock were obtained;

[0125] (3) Preparation of iron-carbon catalytic raw materials: straw and iron ore concentrate were mixed in a mass ratio of 3:1 and placed in a tubular furnace. Nitrogen was continuously introduced and pyrolyzed at 950 °C for 2 h.

[0126] (4) Preparation of sediment-based iron-carbon filler blank: The iron-carbon catalytic raw material prepared in step (3) is mixed with the riverbed mud 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, and an appropriate amount of water (accounting for 40% of the solid mass in the mixture) is added to form a granular sediment-based iron-carbon filler blank, which is then dried at 105° C. for 2 h;

[0127] (5) Firing of composite bottom mud-based iron-carbon filler: The blank obtained in step (4) is placed in a tubular furnace, operated at a heating rate of 10°C / min and continuously introduced with nitrogen, the temperature is raised to a certain temperature of 425°C and preheated for 18 minutes, and then the temperature is further raised to 950°C and the filler is roasted for a certain time of 35 minutes to obtain an iron-carbon filler.

[0128] The obtained iron-carbon filler was subjected to XRD test, and the results were as follows: Figure 5 As shown in the figure, it can be seen that the riverbed mud and tailings waste rock formed a strong skeleton mainly composed of anorthite, mullite, and fayalite at high temperatures, which provided a certain mechanical strength for the composite mud-based iron-carbon filler. It also showed a large zero-valent iron diffraction peak, indicating that the filler contained a large amount of zero-valent iron.

[0129] The obtained iron-carbon filler was subjected to SEM test, and the results were as follows: Figure 6 As shown in the figure, after high-temperature calcination, a strong skeleton of blocks and flakes is formed, and the zero-valent iron is evenly distributed on the skeleton. The filler has abundant pores, which provides conditions for the occurrence of micro-electrolysis reactions.

[0130] Test Reference Example 1 for treating norfloxacin simulated wastewater.

[0131] Calculation showed 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 will enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one 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 present invention. Therefore, the present invention is not limited to the embodiments shown herein but is to be construed in the widest manner consistent with the principles and novel features disclosed herein.

Claims

1. An iron-carbon filler, characterized in that: The raw materials for preparation are calculated by weight and include: 30-60 parts of iron-carbon catalytic raw material; 25-50 parts of riverbed mud; 5-15 parts of tailings waste rock; The iron-carbon catalytic raw material is obtained by pyrolyzing a mixture of straw and iron coarse concentrate; The iron coarse concentrate and tailings waste rock are obtained by processing iron tailings.

2. The iron-carbon filler according to claim 1, characterized in that The preparation raw materials also include 3 to 6 parts of flux; The fluxing agent is selected from boric acid.

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

4. The iron-carbon filler according to any one of claims 1 to 3, characterized in that The iron coarse concentrate and tailings waste rock are obtained by crushing and flotation of iron tailings.

5. The iron-carbon filler according to any one of claims 1 to 4, characterized in that The riverbed mud is washed in advance, and the washing agent is a biosurfactant.

6. A method for preparing an iron-carbon filler according to any one of claims 1 to 5, characterized in that: The following steps are involved: Drying and calcining an iron-carbon filler blank comprising an iron-carbon catalytic raw material, riverbed mud, tailings waste rock, and an optional fluxing agent to obtain an iron-carbon filler; The iron-carbon catalytic raw material is obtained by pyrolyzing a mixture of straw and iron coarse concentrate; The iron coarse concentrate and tailings waste rock are obtained by processing iron tailings.

7. The preparation method according to claim 6, characterized in that The calcination is carried out under oxygen-free or oxygen-deficient conditions; The calcination was carried out according to the following procedure: Preheating stage: heating to 300-450℃, keeping warm for 10-30 minutes; Calcination stage: heating to 900-1000℃, keeping warm for 25-40min; The heating rate of the calcination is 5-15°C / min.

8. The preparation method according to claim 6 or 7, characterized in that The pyrolysis temperature is 850-1000°C.

9. Use of the iron-carbon filler according to any one of claims 1 to 5 or the iron-carbon filler prepared according to the preparation method according to any one of claims 6 to 8 in wastewater treatment.

10. The use according to claim 9, characterized in that The ratio of the iron-carbon filler to the wastewater is (10-20) g:100 mL.

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