A method for preparing two-dimensional water treatment functional materials from fine sludge of single magnetite tailings

Abstract

This invention discloses a method for preparing two-dimensional water treatment functional materials from single magnetite tailings fine sludge. The method uses single magnetite tailings fine sludge as a silicon source, which is then mixed with sodium hydroxide and calcined. The calcined product is then placed in deionized water heated in a water bath to leach out sodium silicate. The product is then centrifuged, and the supernatant is retained. A template agent CTAB is added to the supernatant, and the pH is adjusted. After the reaction, mesoporous silica is crystallized to obtain mesoporous silica. Finally, the obtained mesoporous silica and calcium oxide are placed together in a reactor for a microwave hydrothermal reaction to obtain a well-dispersed water treatment functional material adsorbent. This invention uses low-cost single magnetite tailings fine sludge as the main raw material, and by first converting it into mesoporous silica before preparing highly dispersed two-dimensional water treatment functional materials, it achieves the low-cost preparation of high-performance water treatment functional materials.

Description

Technical Field

[0001] The technical solution of this invention relates to the field of adsorbent synthesis, specifically a method for preparing two-dimensional water treatment functional materials from fine sludge of magnetite tailings. Background Technology

[0002] With industrial development, large amounts of heavy metal ions are discharged into water, making the removal of heavy metal ions from water using water treatment functional materials an important technology. Calcium silicate hydrate, as a common water treatment functional material, possesses excellent adsorption properties and is widely used in fields such as heavy metal ion wastewater treatment.

[0003] Calcium silicate hydrate has shown excellent application prospects in the treatment of heavy metal ion wastewater, but its high synthesis cost and spontaneous aggregation characteristics limit its industrial application. Using tailings sludge as a silicon source to prepare high-performance water treatment functional materials (calcium silicate hydrate) can not only effectively reduce synthesis costs but also mitigate the environmental risks associated with tailings storage. Therefore, finding a suitable preparation method for high-performance water treatment functional materials is of great significance.

[0004] CN112661164A discloses a method for preparing hydrated calcium silicate using waste cement-based materials and non-wood pulping black liquor as raw materials. First, the waste cement-based materials are acid-treated, then mixed with filtered non-wood pulping black liquor to undergo a co-precipitation reaction for 2 hours to obtain hydrated calcium silicate. However, the hydrated calcium silicate prepared by this method is granular with small particle size and poor dispersibility. CN114275790A involves a method for preparing hydrated calcium silicate. First, fly ash is leached with an alkaline agent to obtain a silicate leachate. Then, this leachate is added dropwise at a uniform rate of 15 mL / h to 35 mL / h to a calcium hydroxide suspension, stirred, and heated to obtain hydrated calcium silicate gel. The hydrated calcium silicate gel is then mixed with an organic alcohol solvent and subjected to azeotropic distillation, followed by separation, drying, and calcination to expand the pores. However, this method has limitations due to the need to control the dropping rate and perform the pore-expansion process, resulting in a long preparation time. CN108584969A discloses a method for preparing hydrated calcium silicate using industrial steel slag. First, a strong alkali activator is prepared by mixing sodium hydroxide solution with water glass. Then, industrial steel slag is added to the activator solution, stirred, and heated to obtain a suspension. The suspension is centrifuged to remove excess strong alkali activator, and then ultrasonicated to obtain a particulate suspension. This is then mixed with unreacted steel slag particles and centrifuged at low speed to obtain nano-hydrated calcium silicate nanosheets. However, this method has the limitation of complex operation due to the need for excess activator. The Eisinas team (Ceramics International, 2023, 49(9): 14886-14894) provided a one-step hydrothermal synthesis method for hydrated calcium silicate using commercially available calcium carbonate and silica. However, this method is costly, and the hydrated calcium silicate has poor dispersibility, affecting Cu. 2+ The maximum adsorption capacity is only 142 mg / g.

[0005] Tailings are a major type of industrial solid waste generated during the processing of metallic and non-metallic minerals. Currently, my country's accumulated tailings have reached 19.5 billion tons, with a comprehensive tailings utilization rate of only 10%. Accumulated tailings not only occupy valuable storage land but also cause environmental pollution and pose risks of dam failures, landslides, and collapses. Therefore, the comprehensive utilization of tailings has attracted widespread attention. Examples include recovering valuable metallic elements, producing building materials (i.e., concrete, fired bricks, glass ceramics, wall materials, etc.), manufacturing functional ceramics, and using them as soil conditioners and micronutrient fertilizers. Common types of tailings include fluorite tailings, molybdenum tailings, vanadium-titanium magnetite tailings, single magnetite tailings, and gold tailings. Single magnetite tailings are widely distributed and have large reserves in my country. Generally, single magnetite tailings are mainly composed of quartz and small amounts of metallic elements, with SiO2 content reaching over 40%. The chemical composition and mineralogical properties of single magnetite tailings are similar to clay, consisting of silicate with a silica framework formed by [SiO4] tetrahedra. This indicates that single magnetite tailings have the potential to be used as a sustainable material by adjusting the framework structure. However, due to the difficulty in completely removing numerous impurities, the industrial utilization rate is low, and current research on its application is still limited. Summary of the Invention

[0006] This invention addresses the shortcomings of current technologies by providing a method for preparing highly dispersible two-dimensional water treatment functional materials from single magnetite tailings fine sludge. The method uses alkali-treated single magnetite tailings fine sludge as the silicon source. First, the single magnetite tailings fine sludge is mixed with sodium hydroxide and calcined. Then, the calcined product is placed in deionized water heated in a water bath to leach out sodium silicate. The product is then centrifuged, and the supernatant is retained. A template agent, CTAB, is added to the supernatant, and the pH is adjusted. After the reaction, crystallization yields mesoporous silica. Finally, the obtained mesoporous silica and calcium oxide are placed together in a reactor for a microwave hydrothermal reaction to obtain a well-dispersible water treatment functional material. This invention uses low-cost single magnetite tailings fine sludge as the main raw material, converting it into mesoporous silica before preparing the highly dispersible two-dimensional water treatment functional material, thus achieving low-cost preparation of high-performance water treatment functional materials.

[0007] The technical solution adopted by this invention to solve this technical problem is:

[0008] A method for preparing two-dimensional water treatment functional materials from fine sludge of single magnetite tailings, the method comprising the following steps:

[0009] (1) Place the fine mud of single magnetite tailings and sodium hydroxide in a muffle furnace at a mass ratio of 0.8:1 to 2:1 and roast at 400 to 800°C for 1 to 4 hours. After roasting, cool to room temperature to obtain roasted product.

[0010] (2) Place the calcined product obtained in step (1) in deionized water, place the above suspension in a water bath, heat and stir, and cool to room temperature after the reaction is completed; centrifuge the product, retain the supernatant to obtain crude silicon solution;

[0011] 8–20 g of the calcined product is added to every 100 mL of deionized water;

[0012] (3) Add template agent CTAB to crude silicon solution and adjust pH. React for 1-4 hours, then place in an oven for crystallization. After crystallization, centrifuge and dry to obtain mesoporous silicon.

[0013] (4) Add the mesoporous silica and calcium oxide obtained in step (3) to deionized water, and then sonicate the mixture for 15 to 30 minutes.

[0014] For each 70 mL of deionized water, add 0.1–0.5 g of mesoporous silica;

[0015] (5) Transfer the mixture obtained in step (3) to a reaction vessel, and then place it in a microwave hydrothermal synthesizer for microwave hydrothermal reaction. After the reaction is completed and cooled to room temperature, filter, wash and dry the product to obtain a two-dimensional water treatment functional material.

[0016] Step (2) The water bath temperature is 60-80℃ and the water bath heating time is 0.5-2h.

[0017] In step (3), the amount of template agent CTAB added per 100 mL of crude silica solution is 0.5–2 g, the pH value is 8–12, the crystallization time is 4–24 h, and the crystallization temperature is 40–100 °C.

[0018] In step (4), the mass ratio of mesoporous silicon to calcium oxide is 0.5 to 2.

[0019] In step (5), the microwave hydrothermal reaction temperature is 100-210℃ and the hydrothermal reaction time is 1-4h.

[0020] The composition and content range of the single magnetite tailings fine mud include: 40% to 70% SiO2, 5% to 20% Al2O3, 5% to 25% CaO, 5% to 30% Fe2O3, 5% to 15% MgO and 2% to 10% other trace components.

[0021] The two-dimensional water treatment functional material prepared by the method is used for adsorbing Cu. 2+ .

[0022] The above-mentioned method for preparing two-dimensional water treatment functional materials from single magnetite tailings fine mud involves raw materials, reagents, and equipment other than single magnetite tailings fine mud, all of which are obtained through known means, and the operation process is mastered by those skilled in the art.

[0023] The essential features of this invention are:

[0024] This invention employs an alkali fusion method to treat fine mud from single magnetite tailings, and generates mesoporous silica from the alkali-activated crude silica by adding a template agent. First, the fine mud from single magnetite tailings is mixed with sodium hydroxide and calcined. Then, the crude silica is leached under water bath heating. Next, a template agent is added to the crude silica solution to prepare mesoporous silica. Finally, the obtained mesoporous silica is mixed with calcium oxide and added to a reaction vessel for microwave hydrothermal reaction to obtain a water treatment functional material with good dispersibility.

[0025] The beneficial effects of this invention are:

[0026] (1) Compared with water treatment functional materials (hydrated calcium silicate) prepared using chemical reagents as silicon sources, using single magnetite tailings fine mud as silicon source effectively reduces production costs. At the same time, the process described in this invention significantly improves the dispersibility of water treatment functional materials (hydrated calcium silicate), making its adsorption performance more excellent.

[0027] (2) Compared with CN112661164A, the water treatment functional material (hydrated calcium silicate) prepared by the present invention is in the form of layers and has better dispersibility.

[0028] (3) Compared with CN107721228A, the production process of the present invention is simple, and there is no need to expand the hole or control the dripping rate.

[0029] (4) Compared with CN108584969A, the sample prepared by the present invention has higher purity, up to 98.6%, and does not require an activator, so there is no need to remove excess activator.

[0030] (5) Single magnetite tailings fine mud has the characteristics of low price, large stockpile, and high environmental risk in the stockpile area. Using it as the main raw material to prepare high-performance water treatment functional materials is in line with the development concept of "turning waste into treasure". Attached Figure Description

[0031] Figure 1 TEM image of the two-dimensional water treatment functional material prepared in Example 1;

[0032] Figure 2 TEM image of the two-dimensional water treatment functional material prepared in Example 2;

[0033] Figure 3 The graph shows the adsorption performance of samples prepared in different ways. Detailed Implementation

[0034] The present invention will be described below with specific embodiments, but the scope of protection of the present invention is not limited to these examples.

[0035] The tailings described in this invention are known materials, specifically fine mud (particle size less than 0.075 mm) from single magnetite tailings in Chengde area, Hebei Province, with the main components shown in Table 1. However, it is not limited to this.

[0036] Table 1. Main chemical composition (wt%) of fine mud from single magnetite tailings

[0037]

[0038] Example 1

[0039] 10g of fine tailings sludge from a single magnetite mine and 8g of sodium hydroxide were weighed and calcined in a muffle furnace at 600℃ for 3 hours. After cooling to room temperature, 16.2g of the calcined product was obtained. This product was then added to 100mL of deionized water, and the mixture was transferred to a water bath. The mixture was heated at 75℃ with stirring for 2 hours. After heating, it was cooled to room temperature and centrifuged, retaining the supernatant to obtain 92mL of crude silica solution. 1g of template agent CTAB was added to this crude silica solution, and the pH was adjusted to 10 with 0.1M dilute hydrochloric acid. The reaction was carried out for 2 hours, followed by crystallization at 60℃ for 8 hours. After crystallization, the mixture was filtered and washed with alcohol to obtain mesoporous silica. 0.3g of mesoporous silica and 0.42g of calcium oxide were added to 70mL of deionized water and sonicated for 15 minutes. The mixture was transferred to a reaction vessel and placed in a microwave hydrothermal synthesizer. The mixture was reacted at 180℃ for 1 hour. After cooling to room temperature, it was filtered, washed, and dried to obtain the water treatment functional material. Add 0.05g of the prepared water treatment functional material to 100mL of Cu 2+ A 400 mg / L copper chloride solution was added and stirred on a magnetic stirrer for 4 hours. After stirring, 10 mL of the solution was taken and placed in a GNST-900 water quality analyzer to measure the Cu content. 2+ concentration.

[0040] Figure 1 The image shows a TEM image of the well-dispersed water treatment functional material prepared in Example 1. Its microstructure is layered and uniformly distributed.

[0041] Table 2. Main chemical composition (wt%) of the two-dimensional water treatment functional material prepared in Example 1.

[0042]

[0043] Example 2

[0044] The other steps are the same as in Example 1, except that "0.3g mesoporous silica and 0.42g calcium oxide are added to 70mL of deionized water" is replaced with "0.3g mesoporous silica and 0.56g calcium oxide are added to 70mL of deionized water".

[0045] TEM Figure 2 The TEM image of the two-dimensional water treatment functional material prepared in Example 2 shows that although the lamellar distribution is worse than that in Example 1, the lamellar distribution is uneven, the growth is irregular, and the framework is relatively loose. Excessive calcium hydroxide and calcium carbonate are also present. However, the prepared water treatment functional material still clearly exhibits a lamellar structure. This demonstrates that appropriately changing the calcium-silicon ratio within the parameter range of the technical solution of this invention will not affect the synthesis of the two-dimensional water treatment functional material.

[0046] Comparative Example 1

[0047] The other steps are the same as in Example 1, except that "microwave hydrothermal reaction at 180°C for 1 hour" is replaced with "microwave hydrothermal reaction at 80°C for 1 hour".

[0048] In Comparative Example 1, the products obtained were calcium hydroxide, calcium carbonate, and unreacted mesoporous silica, indicating that a lower reaction temperature cannot allow mesoporous silica and calcium oxide to react completely.

[0049] Comparative Example 2

[0050] The other steps are the same as in Example 1, except that "microwave hydrothermal reaction at 180°C for 1 hour" is replaced with "hydrothermal reaction at 180°C for 1 hour".

[0051] In Comparative Example 2, the products obtained were calcium hydroxide, calcium carbonate, and unreacted mesoporous silica, indicating that ordinary hydrothermal reaction cannot completely react mesoporous silica and calcium oxide within 1 hour.

[0052] Figure 3 The graphs show the adsorption performance of Examples 1, 2, Comparative Example 1, and Comparative Example 2, where Example 1 shows the adsorption performance of Cu. 2+ The adsorption capacity was 696.52 mg / g. Example 2 showed that Cu... 2+ The adsorption capacity was 652.38 mg / g, and Comparative Example 1 showed an adsorption capacity of 652.38 mg / g for Cu. 2+ The adsorption capacity was 128.56 mg / g, compared to Comparative Example 2 for Cu. 2+ The adsorption capacity was 110.23 mg / g. It is clear that Examples 1 and 2 performed better than the other samples.

[0053] As can be seen from the above embodiments and comparative examples, this invention, based on the alkali fusion treatment of fine magnetite tailings, uses a simple hydrothermal method to prepare a two-dimensional water treatment functional material and improves its dispersibility. The preparation process of this invention is simple, uses abundant tailings as a silicon source, is inexpensive, and can serve as a high-quality heavy metal ion adsorbent.

[0054] The foregoing has shown and described the basic principles and main features of the present invention, as well as its advantages. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

[0055] Matters not covered in this invention are common knowledge.

Claims

1. A method for preparing two-dimensional water treatment functional materials from single magnetite tailings fine sludge, characterized in that the method includes the following steps: (1) Place the fine mud of single magnetite tailings and sodium hydroxide in a muffle furnace at a mass ratio of 0.8:1 to 2:1 and roast at 400 to 800°C for 1 to 4 hours. After roasting, cool to room temperature to obtain the roasted product. (2) Place the calcined product obtained in step (1) in deionized water, place the above suspension in a water bath, heat the water bath at 60-80°C with stirring for 0.5-2 hours, and cool to room temperature after the reaction is completed; centrifuge the product, retain the supernatant to obtain crude silicon solution; 8–20 g of the calcined product is added to every 100 mL of deionized water; (3) Add template agent CTAB to crude silicon solution and adjust pH. React for 1-4 hours, then place in an oven for crystallization. After crystallization, centrifuge and dry to obtain mesoporous silicon. In this process, 0.5–2 g of template agent CTAB is added to every 100 mL of crude silica solution, with a pH value of 8–12. (4) Add the mesoporous silica and calcium oxide obtained in step (3) to deionized water, and then sonicate the mixture for 15 to 30 minutes. The method involves adding 0.1–0.5 g of mesoporous silica to every 70 mL of deionized water; the mass ratio of mesoporous silica to calcium oxide is 0.5–2. (5) Transfer the mixture obtained in step (3) to a reaction vessel and then carry out a microwave hydrothermal reaction. After the reaction is completed and cooled to room temperature, filter, wash and dry the product to obtain a two-dimensional water treatment functional material.

2. The method for preparing two-dimensional water treatment functional materials from single magnetite tailings fine sludge as described in claim 1, characterized in that: In step (3), the crystallization time is 4 to 24 hours and the crystallization temperature is 40 to 100°C.

3. The method for preparing two-dimensional water treatment functional materials from single magnetite tailings fine sludge as described in claim 1, characterized in that: In step (5), the microwave hydrothermal reaction temperature is 100-210℃ and the hydrothermal reaction time is 1-4h.

4. The method for preparing two-dimensional water treatment functional materials from single magnetite tailings fine sludge as described in claim 1, characterized in that: The composition and content range of the single magnetite tailings fine mud include: 40% to 70% SiO2, 5% to 20% Al2O3, 5% to 25% CaO, 5% to 30% Fe2O3, 5% to 15% MgO and 2% to 10% other trace components.

5. The application of the two-dimensional water treatment functional material prepared by the method described in claim 1, characterized in that it is used for adsorbing Cu. 2+ .

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