Method for preparing spherical hydroxyapatite powder by hydrothermal synthesis of tempered hot sludge

Abstract

The application discloses a method for preparing spherical hydroxyapatite powder by hydrothermal synthesis of tempered hot sludge, and realizes phase simplification and directional regulation by online tempering and cooling system control on the basis of hot sludge process and equipment in a steel enterprise, and promotes high enrichment of calcium in a soluble phase; after selective calcium extraction by an acidic solution, impurities are removed by filtration, and efficient extraction of calcium ions can be realized; by using a hydrothermal synthesis process and by using a template agent as an auxiliary, spherical powder material which can be used for preparing a hydroxyapatite coating is synthesized. The technology realizes comprehensive utilization of the hot sludge and controllable preparation of high-quality hydroxyapatite powder, reduces the synthesis cost of the hydroxyapatite, and the prepared nanoscale hydroxyapatite has good sphericity and uniform size, can meet the biological compatibility requirement, and has important significance for high-value resource utilization of the steel sludge.

Description

Technical Field

[0001] This invention belongs to the field of comprehensive utilization technology of metallurgical resources, specifically relating to a method for preparing spherical hydroxyapatite powder by hydrothermal synthesis of quenched hot slag. Background Technology

[0002] The hot quenching process for steel slag utilizes the residual heat (1030~1350℃) of steel slag. Water is sprayed into a sealed container, and then a quenching cover is placed on top. The water vapor generated during the spraying process comes into full contact with the steel slag, producing a large amount of saturated steam that causes the slag to break down and pulverize itself. This process allows the free calcium oxide in the steel slag to be released. f -CaO) and free magnesium oxide ( f The process of fully digesting MgO can eliminate unstable phases in steel slag and improve its activity, thus opening up new avenues for the comprehensive utilization of steel slag.

[0003] Hydroxyapatite is a major inorganic component of human bone tissue, with the molecular formula Ca. 10 (PO4)6(OH)2. Hydroxyapatite possesses high biocompatibility and bioactivity, making it an important material for tissue engineering. Therefore, it is widely used in biomedical fields such as orthopedics, dental restoration, and bio-coatings. Currently, research on hydroxyapatite in bone substitute materials mainly focuses on two aspects: hydroxyapatite coatings and biomimetic regenerative materials for human bone. Hydroxyapatite coatings refer to hard tissue implant materials prepared by coating hydroxyapatite onto the surface of metals such as titanium alloys using physicochemical methods. The corrosion resistance and osteoinductive properties of hydroxyapatite address the safety concerns of titanium alloys and other ceramic (alumina, silicon nitride) matrices in vivo.

[0004] The preparation of hydroxyapatite requires a large amount of calcium source, commonly including calcium nitrate, calcium hydroxide, and calcium chloride. In recent years, many researchers have used waste materials such as fish bones, carbide slag, alkali slag, and biogas slag as calcium sources to prepare hydroxyapatite through solid-phase methods, co-precipitation methods, microemulsion methods, hydrothermal methods, and sol-gel methods, significantly reducing material preparation costs. Patent CN101724677A provides a method for separating and extracting collagen peptides and hydroxyapatite from fish scales through cooking and hot extrusion. This method does not require acid or alkali pretreatment and has good separation and purification effects, but it requires many auxiliary materials and has high raw material standards. Patent CN103318865A discloses a method for synthesizing hydroxyapatite using alkali slag and dilute hydrochloric acid as raw materials through a simple precipitation preparation method. This method has a short preparation process and is simple to operate, but it consumes a large amount of hydrochloric acid during the preparation process, resulting in high costs. Patent CN114180544A discloses a method for synthesizing bone-like hydroxyapatite using carbide slag as raw material through acidic dissolution. This method has good reproducibility and a simple preparation process, but it consumes a large amount of pH adjuster when adjusting the pH value. Patent CN113896180A discloses a method for preparing hydroxyapatite using biogas slag as a calcium source. Although this method has abundant raw materials and low production costs, the preparation process is complex and involves a long high-temperature calcination time. Summary of the Invention

[0005] To overcome the shortcomings of the existing technology, this invention uses converter steelmaking waste slag as raw material, achieves phase regulation through online conditioning and cooling of hot steel slag, selectively extracts calcium components using an acidic system, and prepares hydroxyapatite powder using a hydrothermal synthesis method. This alleviates the enormous pressure on the resource utilization of hot slag and realizes the high added value utilization of hot slag.

[0006] Hot slag is a solid waste generated during the steel industry. Its high calcium content (45%–60%) meets the requirements for preparing hydroxyapatite. Through online conditioning and cooling control during slag discharge, phase simplification and directional regulation can be achieved, promoting high enrichment of calcium in the readily soluble phase. Combined with selective calcium extraction using acidic solutions and hydrothermal synthesis, spherical powder materials for preparing hydroxyapatite coatings can be synthesized. This method not only has a compact process and low production cost, but also solves the bottleneck problem of difficult high-value utilization of steel slag.

[0007] To achieve the above-mentioned objective, this invention provides a method for preparing spherical hydroxyapatite powder via hydrothermal synthesis of tempered hot slag, the method comprising the following steps: ① During the slag removal process in the converter, quenching and tempering materials are added, the cooling regime is controlled, and then the quenched and tempered steel slag is sent to a hot quenching pot to perform hot quenching treatment, thus obtaining hot quenched slag.

[0008] The main components of the hot slag are CaO, MgO, SiO2, Al2O3, FeO, etc.; the mass fraction of CaO in the hot slag is 40~60%.

[0009] ② The hot slag is crushed to 20~300 µm, leached in an acidic solution at 20~70℃ for 30~60 min, while being mechanically stirred, and then filtered to obtain the hot slag leachate.

[0010] ③ Add a phosphorus source to the hot slag leachate obtained in step ② to adjust the calcium-phosphorus molar ratio to 1.67~2, then add a template agent, and at the same time adjust the pH of the solution to 7~12 with an alkaline solution, and use a mechanical stirrer to stir and mix the mixed solution at a speed of 100~200 r / min.

[0011] ④ Transfer the mixed solution obtained in step ③ to a hydrothermal reactor, and simultaneously stir it with a magnetic rotor at a stirring speed of 30 r / min. The reaction temperature is maintained at 100~200℃ (preferably 140~180℃), and the reaction time is 4~6 h. After the reaction is completed, the mixture is aged, and then the resulting slurry is filtered and separated to obtain filtrate and solid product respectively.

[0012] ⑤ The white solid product obtained in step ④ is washed with water, washed with organic solvent, calcined and dried to obtain a white powder, which is hydroxyapatite.

[0013] In the above technical solution, further, the conditioning material mentioned in step ① is one or more of potassium silicate, magnesium silicate, aluminum silicate, and silicon dioxide. The conditioning material is added to the steel slag to adjust the basicity (calcium-silicon ratio) of the steel slag to 1.5~2.5. The addition method is bottom spreading combined with slag discharge feeding by a feeder.

[0014] Furthermore, the cooling system control mentioned in step ① refers to covering the slag pot and keeping it warm after slag removal, cooling it to 1250~1350℃ at a rate of less than 5℃ / min.

[0015] Furthermore, the acidic solution in step ② is any one or more of acetic acid, nitric acid, and nitrous acid, and the concentration of the acidic solution is 0.1~1 mol / L; the liquid-to-solid ratio of the acidic solution to the hot slag is 5~10 mL / g.

[0016] Furthermore, the mechanical stirring rate in step ② is 10~60 r / min, and the stirring time is 30~60 min.

[0017] Furthermore, the hot slag leachate described in step ③ is the calcium source.

[0018] Furthermore, the phosphorus source mentioned in step ③ is any one or more of phosphoric acid, phosphate, dihydrogen phosphate, and hydrogen phosphate.

[0019] Furthermore, the template agent in step ③ is any one or more of sucrose solution, calcium carbonate solution, and hexadecyltrimethylammonium bromide (CTAB) solution. The template agent mainly serves to provide nucleation sites in the reaction, allowing the hydroxyapatite to develop in an orderly, spherical direction based on these sites during subsequent formation, ultimately resulting in morphologically controllable spherical hydroxyapatite. The concentration of the sucrose solution and hexadecyltrimethylammonium bromide (CTAB) solution is 0.10–0.28 mmol / L, and the volume is 50–100 mL; the concentration of the calcium carbonate solution is 0.25 mol / L, and the volume is 100–200 mL.

[0020] Furthermore, the alkaline solution mentioned in step ③ is one of ammonia water, potassium hydroxide, or sodium hydroxide solution.

[0021] Furthermore, the aging process described in step ④ is carried out at a temperature of 20~100℃ for 12~24 h.

[0022] Furthermore, the organic solvent in step ⑤ is selected as a methanol solution or an ethanol solution.

[0023] Furthermore, the calcination temperature in step ⑤ is 300~500℃, the calcination time is 3 h and the holding time is 2 h.

[0024] Since steel slag contains elements such as calcium, magnesium, aluminum, silicon, and iron, and calcium is present in a complex state and dispersed in phases such as dicalcium silicate and tricalcium silicate, it is difficult to efficiently and selectively extract and separate calcium. The above-mentioned technical solution of the present invention promotes the enrichment of calcium in the soluble phase of steel slag by adjusting the composition of steel slag and controlling the cooling process, thereby increasing the leaching rate of calcium in steel slag and effectively inhibiting the leaching of other elements.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows: ① This invention uses steel slag as raw material and obtains conditioned hot slag through the control of composition and cooling process to provide a high-purity calcium source for the preparation of hydroxyapatite, which reduces the synthesis cost of hydroxyapatite compared with pure chemical raw materials.

[0026] ② This invention uses an acidic solution to leach the hot slag leachate, and has developed a calcium source leachate with high purity. The leaching rate of other elements in the hot slag is negligible.

[0027] ③ This invention utilizes a template agent for hydrothermal synthesis to prepare nano-sized hydroxyapatite with good sphericity and uniform size. This type of morphological hydroxyapatite has good drug delivery and penetration capabilities in biomedicine.

[0028] ④ This invention is a hydroxyapatite that can be applied to biomedicine, prepared by hydrothermal synthesis. The prepared hydroxyapatite meets the biocompatibility requirements and can be used to prepare bio-coatings, which is of great significance for the high-value-added resource utilization of steel slag. Attached Figure Description

[0029] Figure 1 This is a process flow diagram of the hydrothermal synthesis of spherical hydroxyapatite powder using tempered hot slag according to the present invention. Figure 2 The image shows a scanning electron microscope (SEM) image (10 μm) of the hydroxyapatite obtained in Example 1. Figure 3 The image shows a scanning electron microscope (SEM) image (100 nm) of the hydroxyapatite obtained in Example 1. Figure 4 The image shows the X-ray diffraction pattern of the hydroxyapatite obtained in Example 1. Detailed Implementation

[0030] To more clearly present the technical features and beneficial effects of the present invention, the following embodiments and accompanying drawings will be used for detailed explanation. Those skilled in the art should understand that the following embodiments are for illustrative purposes only and are not intended to limit the invention in any way.

[0031] Unless otherwise specified, the experimental methods described in the following examples are conventional methods; the reagents, materials, instruments and equipment mentioned are all commercially available unless otherwise specified.

[0032] A method for preparing spherical hydroxyapatite powder by hydrothermal synthesis of tempered hot slag is described in the attached process flow chart. Figure 1 As shown, the method includes the following steps: ① During the slag removal process in the converter, quenching and tempering materials are added, the cooling regime is controlled, and then the quenched and tempered steel slag is sent to a hot quenching pot to perform hot quenching treatment to obtain hot quenched slag; ② The hot slag is crushed to 20~300 µm and leached in an acidic solution at 20~70℃ for 30~60 min while being mechanically stirred to obtain a hot slag leachate; ③ Add a phosphorus source to the hot slag leachate obtained in step ② to adjust the calcium-phosphorus molar ratio to 1.67~2, then add a template agent, and at the same time adjust the pH of the solution to 7~12 with an alkaline solution, and use a mechanical agitator to stir and mix the mixed solution. ④ Transfer the mixed solution obtained in step ③ to a hydrothermal reactor, and stir it with a magnetic rotor at a stirring speed of 30 r / min. The reaction temperature is maintained at 100~200℃ and the reaction time is 4~6 h. After the reaction is completed, the mixture is aged, and then the resulting slurry is filtered and separated to obtain filtrate and solid product respectively. ⑤ The solid product obtained in step ④ is washed with water, washed with organic solvent, calcined and dried to obtain a white powder, which is hydroxyapatite.

[0033] The steel slag raw materials used in the following embodiments are all from a steel plant in Northeast China. Any aspects not specifically described in the following embodiments are the same as those described in the detailed embodiments above.

[0034] Example 1 A method for preparing spherical hydroxyapatite powder by hydrothermal synthesis of tempered hot slag, the process flow is as follows: ① During the slag removal process in the converter, potassium silicate is added to the molten slag to adjust the basicity (calcium-silicon ratio) of the steel slag to 1.5. The slag pot is covered and kept warm, and cooled to 1250 ℃ at a rate of 4.5 ℃ / min. Then it is sent to a hot quenching pot to perform hot quenching treatment on the quenched and tempered steel slag to obtain hot quenched slag.

[0035] ② Take 20 g of the hot slag, crush and grind it to 20~300 µm, mix it with 100 mL of 0.5 mol / L acetic acid solution at a liquid-solid ratio of 5:1, leach at 50 ℃ for 30 min, and stir with a mechanical stirrer. Filter to obtain the hot slag leachate.

[0036] ③ Measure 100 mL of 0.054 mol / L phosphoric acid solution and add it dropwise to 100 mL of hot slag leachate using a peristaltic pump. At the same time, add 100 mL of 0.25 mmol / L sucrose solution to the mixed solution. Adjust the pH value to 10 with ammonia water and stir the solution with a mechanical stirrer.

[0037] ④ Transfer the above mixed solution to a hydrothermal reactor and react at 140 °C for 4 h, while stirring with a magnetic rotor at a stirring speed of 30 r / min.

[0038] ⑤ The stirred white turbid liquid was filtered and separated using a vacuum filter. The precipitate obtained after separation was washed with ethanol 5 times and then sent to a muffle furnace to be calcined at 500 ℃ for 3 h and kept at that temperature for 2 h; thus, hydroxyapatite was obtained.

[0039] In Example 1, during the preparation of spherical hydroxyapatite powder, the leaching rate of the hot slag is shown in Table 1. The leaching rate of calcium reached 41%, indicating that the method of the present invention promotes the enrichment of calcium in the readily soluble phase of steel slag and effectively inhibits the leaching of other elements, achieving efficient extraction of calcium ions. Meanwhile, [the following text is missing from the original extract]. Figure 2 and attached Figure 3 It can be demonstrated that the sphericity of the hydroxyapatite powder can reach 85%, with uniform size and an average size of approximately 60 nm, making it a nanoscale hydroxyapatite powder. The X-ray diffraction pattern of the hydroxyapatite is attached. Figure 4As shown, the molecular structure before calcination is Ca3(PO4)2, and the molecular structure after calcination is Ca 10 (PO4)6(OH)2.

[0040] Table 1. Leaching rate of hot slag corresponding to Example 1

[0041] Example 2 A method for preparing spherical hydroxyapatite powder by hydrothermal synthesis of tempered hot slag, the process flow is as follows: ① During the slag removal process in the converter, magnesium silicate is added to the molten slag to adjust the basicity (calcium-silicon ratio) of the steel slag to 2.0. The slag pot is covered and kept warm, and cooled to 1250 ℃ at a rate of 4.5 ℃ / min. Then it is sent to a hot quenching pot to perform hot quenching treatment on the quenched and tempered steel slag to obtain hot quenched slag.

[0042] ② Take 10 g of the hot slag, crush and grind it to 20~300 µm, mix it with 100 mL of 0.5 mol / L nitric acid solution at a liquid-solid ratio of 10:1, leach it at 50 ℃ for 60 min, and stir it with a mechanical stirrer. Filter and separate to obtain the hot slag leachate.

[0043] ③ Measure 100 mL of 0.054 mol / L phosphoric acid solution and add it dropwise to 100 mL of hot slag leachate using a peristaltic pump. At the same time, add 100 mL of 0.25 mmol / L sucrose solution to the mixed solution. Adjust the pH value to 11 with sodium hydroxide solution and stir the solution with a mechanical stirrer.

[0044] ④ Transfer the above mixed solution to a reaction vessel and react at 140 °C for 6 h, while stirring with a magnetic rotor at a stirring speed of 30 r / min.

[0045] ⑤ The stirred white turbid liquid was filtered and separated using a vacuum filter. The precipitate obtained after separation was washed five times with methanol and then sent to a muffle furnace for calcination at 300 °C for 3 h and held at that temperature for 2 h to obtain hydroxyapatite.

[0046] In Example 2, during the preparation of spherical hydroxyapatite powder, the leaching rate of the hot slag is shown in Table 2. The sphericity of the obtained hydroxyapatite powder reached 80%, and it was nano-hydroxyapatite with uniform size and an average size of about 45 nm.

[0047] Table 2 Leaching rate of hot slag corresponding to Example 2

[0048] Example 3 A method for preparing spherical hydroxyapatite powder by hydrothermal synthesis of tempered hot slag, the process flow is as follows: ① During the slag removal process in the converter, potassium silicate is added to the molten slag to adjust the basicity (calcium-silicon ratio) of the steel slag to 1.5. The slag pot is covered and kept warm, and cooled to 1300 ℃ at a rate of 4.0 ℃ / min. Then it is sent to a hot quenching pot to perform hot quenching treatment on the quenched and tempered steel slag to obtain hot quenched slag.

[0049] ② Take 20 g of hot slag, crush and grind it to 20~300 µm, mix it with 100 mL of 1 mol / L nitrous acid solution and the prepared slag powder at a liquid-solid ratio of 5:1, leach at 60 ℃ for 60 min, and stir with a mechanical stirrer at the same time. Filter to obtain the hot slag leachate.

[0050] ③ Measure 100 mL of 0.040 mol / L disodium hydrogen phosphate solution and add it dropwise to 100 mL of hot slag leachate using a peristaltic pump. At the same time, add 100 mL of a mixture of 0.25 mmol / L sucrose solution and 50 mL of 0.12 mmol CTAB solution to the mixed solution. Adjust the pH to 12 with ammonia water and stir the solution with a mechanical stirrer.

[0051] ④ Transfer the above mixed solution to a reaction vessel and react at 150 °C for 4 h, while stirring with a magnetic rotor at a stirring speed of 30 r / min.

[0052] ⑤ The stirred white turbid liquid was filtered using a vacuum filter. The precipitate obtained after separation was washed five times with ethanol and then placed in an oven to be calcined at 400 °C for 3 h and kept at that temperature for 2 h. Hydroxyapatite was then obtained.

[0053] In Example 3, during the preparation of spherical hydroxyapatite powder, the leaching rate of the hot slag is shown in Table 3. The sphericity of the obtained hydroxyapatite powder reached 78%, and it was nano-hydroxyapatite with uniform size and an average size of about 57 nm.

[0054] Table 3. Leaching rate of hot slag corresponding to Example 3

[0055] Example 4 A method for preparing spherical hydroxyapatite powder by hydrothermal synthesis of tempered hot slag, the process flow is as follows: ① During the slag removal process in the converter, silica is added to the molten slag to adjust the basicity (calcium-silicon ratio) of the steel slag to 2.5. The slag pot is covered and kept warm, and cooled to 1350 ℃ at a rate of 4.5 ℃ / min. Then it is sent to a hot quenching pot to perform hot quenching treatment on the quenched and tempered steel slag to obtain hot quenched slag.

[0056] ② Take 20 g of hot slag, crush and grind it to 20~300 µm, mix it with 100 mL of 0.75 mol / L acetic acid solution at a liquid-solid ratio of 5:1, leach it at 30 ℃ for 60 min, and stir it with a mechanical agitator. Filter and separate to obtain steel slag leachate.

[0057] ③ Measure 100 mL of 0.040 mol / L disodium hydrogen phosphate solution and add it dropwise to 100 mL of hot slag leachate using a peristaltic pump. At the same time, add 100 mL of a mixture of 0.25 mmol / L sucrose solution and 50 mL of 0.12 mmol CTAB solution to the mixed solution. Adjust the pH to 10 with ammonia water and stir the solution with a mechanical stirrer.

[0058] ④ Transfer the above mixed solution to a reaction vessel and react at 140 °C for 5 h, while stirring with a magnetic rotor at a stirring speed of 30 r / min.

[0059] ⑤ The stirred white turbid liquid was filtered using a vacuum filter. The precipitate obtained after separation was washed five times with ethanol and then placed in an oven to be calcined at 300 °C for 3 h and kept at that temperature for 2 h. Hydroxyapatite was then obtained.

[0060] In Example 4, during the preparation of spherical hydroxyapatite powder, the leaching rate of the hot slag is shown in Table 4. The sphericity of the obtained hydroxyapatite powder reached 87%, and it was nano-hydroxyapatite with uniform size and an average size of about 66 nm.

[0061] Table 4. Leaching rate of hot slag corresponding to Example 4

[0062] Example 5 A method for preparing spherical hydroxyapatite powder by hydrothermal synthesis of tempered hot slag, the process flow is as follows: ① During the slag removal process in the converter, aluminum silicate is added to the molten slag to adjust the basicity (calcium-silicon ratio) of the steel slag to 1.5. The slag pot is covered and kept warm, and cooled to 1250 ℃ at a rate of 3.5 ℃ / min. Then it is sent to a hot quenching pot to perform hot quenching treatment on the quenched and tempered steel slag to obtain hot quenched slag.

[0063] ② Take 20 g of hot slag, crush and grind it to 20~300 µm, mix it with 100 mL of 0.75 mol / L acetic acid solution at a liquid-solid ratio of 5:1, leach at 70 ℃ for 40 min, and stir with a mechanical agitator. Filter to obtain steel slag leachate.

[0064] ③ Measure 100 mL of 0.035 mol / L sodium phosphate solution, and use a peristaltic pump to add the measured disodium hydrogen phosphate solution dropwise to 100 mL of hot slag leachate. At the same time, add 100 mL of a mixture of 0.25 mmol / L sucrose solution and 50 mL of 0.12 mmol CTAB solution to the mixed solution. Adjust the pH value to 10 with ammonia water and stir the solution with a mechanical stirrer.

[0065] ④ Transfer the above mixed solution to a reaction vessel and react at 150 °C for 4 h, while stirring with a magnetic rotor at a stirring speed of 30 r / min.

[0066] ⑤ The stirred white turbid liquid was filtered using a vacuum filter. The precipitate obtained after separation was washed five times with ethanol and then placed in an oven to be calcined at 300 °C for 3 h and kept at that temperature for 2 h. Hydroxyapatite was then obtained.

[0067] In Example 5, during the preparation of spherical hydroxyapatite powder, the leaching rate of the hot slag is shown in Table 5. The sphericity of the obtained hydroxyapatite powder reached 85%, and it was nano-hydroxyapatite with uniform size and an average size of about 67 nm.

[0068] Table 5. Leaching rate of hot slag corresponding to Example 5

[0069] Example 6 A method for preparing spherical hydroxyapatite powder by hydrothermal synthesis of tempered hot slag, the process flow is as follows: ① During the slag removal process in the converter, silica is added to the molten slag to adjust the basicity (calcium-silicon ratio) of the steel slag to 2.0. The slag pot is covered and kept warm, and cooled to 1250 ℃ at a rate of 4.5 ℃ / min. Then it is sent to a hot quenching pot to perform hot quenching treatment on the quenched and tempered steel slag to obtain hot quenched slag.

[0070] ② Take 20 g of hot slag, crush and grind it to 20~300 µm, mix it with 100 mL of 0.75 mol / L nitric acid solution at a liquid-solid ratio of 5:1, leach it at 50 ℃ for 50 min, and stir it with a mechanical agitator. Filter and separate to obtain steel slag leachate.

[0071] ③ Measure 100 mL of 0.040 mol / L disodium hydrogen phosphate solution and add it dropwise to 100 mL of hot slag leachate using a peristaltic pump. At the same time, add 100 mL of 0.25 mmol / L sucrose solution to the mixed solution. Adjust the pH value to 11 with sodium hydroxide solution and stir the solution with a mechanical stirrer.

[0072] ④ Transfer the above mixed solution to a reaction vessel and react at 160 °C for 4 h, while stirring with a magnetic rotor at a stirring speed of 30 r / min.

[0073] ⑤ The stirred white turbid liquid was filtered using a vacuum filter. The precipitate obtained after separation was washed five times with ethanol and then placed in an oven to be calcined at 300 °C for 3 h and kept at that temperature for 2 h. Hydroxyapatite was then obtained.

[0074] In Example 6, during the preparation of spherical hydroxyapatite powder, the leaching rate of the hot slag is shown in Table 6. The sphericity of the obtained hydroxyapatite powder reached 85%, and it was nano-hydroxyapatite with uniform size and an average size of about 69 nm.

[0075] Table 6. Leaching rate of hot slag corresponding to Example 6

[0076] Example 7 A method for preparing spherical hydroxyapatite powder by hydrothermal synthesis of tempered hot slag, the process flow is as follows: ① During the slag removal process in the converter, potassium silicate is added to the molten slag to adjust the basicity (calcium-silicon ratio) of the steel slag to 1.5. The slag pot is covered and kept warm, and cooled to 1250 ℃ at a rate of 4.5 ℃ / min. Then it is sent to a hot quenching pot to perform hot quenching treatment on the quenched and tempered steel slag to obtain hot quenched slag.

[0077] ② Take 10 g of hot slag, crush and grind it to 20~300 µm, mix it with 100 mL of 0.75 mol / L nitrous acid solution at a liquid-solid ratio of 10:1, leach at 50 ℃ for 60 min, and stir with a mechanical agitator. Filter to obtain steel slag leachate.

[0078] ③ Measure 100 mL of 0.035 mol / L sodium phosphate solution, and use a peristaltic pump to add the measured disodium hydrogen phosphate solution dropwise to 100 mL of hot slag leachate. At the same time, add 100 mL of 0.25 mol / L calcium carbonate solution dropwise to the mixed solution, adjust the pH value to 12 with potassium hydroxide solution, and stir it with a mechanical stirrer.

[0079] ④ Transfer the above mixed solution to a reaction vessel and react at 150 °C for 5 h, while stirring with a magnetic rotor at a stirring speed of 30 r / min.

[0080] ⑤ The stirred white turbid liquid was filtered using a vacuum filter. The precipitate obtained after separation was washed five times with ethanol and then placed in an oven to be calcined at 300 °C for 3 h and kept at that temperature for 2 h. Hydroxyapatite was then obtained.

[0081] In Example 7, during the preparation of spherical hydroxyapatite powder, the leaching rate of the hot slag is shown in Table 7. The calcium leaching rate was 42%, achieving efficient extraction of calcium ions. The sphericity of the obtained hydroxyapatite powder reached 85%, and it was nano-hydroxyapatite with uniform size and an average size of about 60 nm.

[0082] Table 7 Leaching rate of hot slag corresponding to Example 7

[0083] For anyone skilled in the art, many possible variations and modifications can be made to the technical solutions of this invention, or equivalent embodiments can be modified based on the disclosed technical content, without departing from the scope of the technical solutions of this invention. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of this invention without departing from the content of the technical solutions of this invention should still fall within the protection scope of the technical solutions of this invention.

Claims

1. A method for preparing spherical hydroxyapatite powder by hydrothermal synthesis of tempered hot slag, characterized in that, The method includes the following steps: ① During the slag removal process in the converter, quenching and tempering materials are added, the cooling regime is controlled, and then the quenched and tempered steel slag is sent to a hot quenching pot to perform hot quenching treatment to obtain hot quenched slag. ② The hot-cured residue is crushed to 20~300 µm and leached in an acidic solution at 20~70℃ for 30~60 min while being mechanically stirred to obtain a hot-cured residue leachate; ③ Add a phosphorus source to the hot slag leachate obtained in step ② to adjust the calcium-phosphorus molar ratio to 1.67~2, then add a template agent, and at the same time adjust the pH of the solution to 7~12 with an alkaline solution, and use a mechanical agitator to stir and mix the mixed solution. ④ Transfer the mixed solution obtained in step ③ to a hydrothermal reactor, and stir it with a magnetic rotor at a stirring speed of 30 r / min. The reaction temperature is maintained at 100~200℃ and the reaction time is 4~6 h. After the reaction is completed, the mixture is aged, and then the resulting slurry is filtered and separated to obtain filtrate and solid product respectively. ⑤ The solid product obtained in step ④ is washed with water, washed with organic solvent, calcined and dried to obtain a white powder, which is hydroxyapatite; The conditioning material mentioned in step ① is one or more of potassium silicate, magnesium silicate, aluminum silicate, and silicon dioxide. The conditioning material is added to the steel slag to adjust the basicity of the steel slag to 1.5~2.

5. The addition method is bottom spreading combined with slag discharge feeding by a feeder. The concentration of the acidic solution is 0.1~1 mol / L; the liquid-to-solid ratio of the acidic solution to the hot slag is 5~10 mL / g; and the mechanical stirring rate is 10~60 r / min. The template agent mentioned in step ③ is any one or more of sucrose solution, calcium carbonate solution, and hexadecyltrimethylammonium bromide solution; The calcination temperature in step ⑤ is 300~500℃, the calcination time is 3 h and the holding time is 2 h; The cooling process described in step ① involves covering the slag pot after slag removal and keeping it warm, then cooling it to 1250~1350℃ at a rate of less than 5℃ / min.

2. The method according to claim 1, characterized in that, The concentrations of the sucrose solution and the hexadecyltrimethylammonium bromide solution are 0.10~0.28 mmol / L; the concentration of the calcium carbonate solution is 0.25 mol / L.

3. The method according to claim 1, characterized in that, The acidic solution mentioned in step ② is any one or more of acetic acid, nitric acid, and nitrous acid.

4. The method according to claim 1, characterized in that, The phosphorus source mentioned in step ③ is any one or more of phosphoric acid and phosphate.

5. The method according to claim 4, characterized in that, The phosphate is a dihydrogen phosphate or a hydrogen phosphate.

6. The method according to claim 1, characterized in that, The alkaline solution mentioned in step ③ is one of ammonia water, potassium hydroxide, or sodium hydroxide solution.

7. The method according to claim 1, characterized in that, The aging process in step ④ is carried out at a temperature of 20~100℃ for 12~24 hours.

8. The method according to claim 1, characterized in that, The organic solvent used in step ⑤ is either a methanol solution or an ethanol solution.

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