A high-strength fluorite ball and preparation method thereof

Abstract

The invention relates to the technical field of fluorite balls, in particular to a high-strength fluorite ball and a preparation method thereof. The fluorite ball is prepared from the following raw materials in parts by weight: 85-95 parts of fluorite powder, 5-10 parts of a composite binder, and 1-5 parts of epoxy carbon fibers; the composite binder consists of an inorganic binder, a carboxyl-modified organic silicone resin, and core-shell structured silica. The fluorite ball prepared by the invention has high strength and can effectively reduce the breakage rate of the fluorite ball during storage, transportation, and use.

Description

Technical Field

[0001] The invention relates to the technical field of fluorite balls, in particular to a high-strength fluorite ball and a preparation method thereof. Background Art

[0002] In the steel industry, fluorite is widely used as a flux for iron and steel making. The main functions of fluorite are to reduce smelting temperature, save fuel consumption, reduce slag viscosity, increase slag fluidity, and facilitate the smooth discharge of slag from metal. In recent years, high-grade fluorite ore has been mined in large quantities, and the reserves have continued to decline. The price of high-grade fluorite lumps in the market has continued to rise, causing the glass, ceramics, chemical and other industries to switch to high-purity flotation fluorite powder. However, in the metallurgical industry, due to process conditions, fluorite powder cannot be directly put into the furnace as a powder. A binder needs to be added. Through stirring and high-pressure forming processes, the fluorite powder is processed into pellets. This is currently one of the best ways to solve the problem of fluorite powder replacing fluorite lumps.

[0003] Fluorite balls have the advantages of uniform particle size, uniform composition and customization, and have been increasingly used in the metallurgical industry. In the steelmaking and refining production process, the loading and transportation process of fluorite balls is relatively complicated. Generally, they are stored in underground silos, transported by cars, and then transported to the high-level silo of the refining furnace through multiple belts. Finally, they are fed into the steelmaking and refining furnace by a high-level vibrating feeder. In this process, the loss of fluorite pellets increases and the crushing rate increases, which not only increases the consumption of pellets, but also seriously affects the working efficiency of the steel plant. The large amount of dust generated will also pollute the environment and seriously endanger the health of the operators. Summary of the invention

[0004] Purpose of the invention: In view of the above technical problems, the present invention proposes a high-strength fluorite ball and a preparation method thereof.

[0005] The technical solutions adopted are as follows:

[0006] A high-strength fluorite ball is made from the following raw materials in parts by weight:

[0007] 85-95 parts of fluorite powder, 5-10 parts of composite binder, 1-5 parts of epoxy carbon fiber;

[0008] The composite binder is composed of an inorganic binder, a carboxyl-modified silicone resin, and core-shell structured silica;

[0009] The preparation method of the epoxy carbon fiber is as follows:

[0010] The silane coupling agent KH-560 is added to a mixed solvent consisting of anhydrous ethanol and deionized water, and then subjected to ultrasonic treatment to obtain a mixed solution. The carbon fiber is acidified with concentrated nitric acid and then added to the mixed solution. The mixture is heated to reflux for 10-30 hours and then returned to room temperature. The collected carbon fiber is filtered, washed, and dried.

[0011] The mass ratio of the inorganic binder, the carboxyl-modified silicone resin and the core-shell structured silica is 5-10:1-5:1-2.

[0012] Furthermore, the inorganic binder is composed of aluminum sol and water glass in a mass ratio of 1-5:1-5.

[0013] Furthermore, the inorganic binder consists of aluminum sol and water glass in a mass ratio of 1:1.

[0014] Furthermore, the preparation method of the carboxyl-modified silicone resin is as follows:

[0015] Under nitrogen protection, diphenyldihydroxysilane, methyldiethoxysilane and cation exchange resin are mixed, heated to 90-100°C and reacted for 10-30 hours. After the reaction is completed, the filtrate is filtered and the filtrate is distilled under reduced pressure to obtain hydrogen-containing polysiloxane. Under nitrogen protection, allylmalonic acid is heated to 105-110°C, chloroplatinic acid is added after it is melted, and the hydrogen-containing polysiloxane is added after stirring and mixing. The reaction is kept warm for 1-10 hours and then distilled under reduced pressure.

[0016] Furthermore, the core-shell structured silica consists of a nano-silica core and an aluminum dihydrogen phosphate shell.

[0017] Furthermore, the preparation method of the core-shell structured silica is as follows:

[0018] Add aluminum hydroxide to the phosphoric acid aqueous solution, heat to reflux and keep warm for 1-10 hours, stop heating, cool naturally to room temperature to obtain aluminum dihydrogen phosphate gel, add nano-silicon dioxide to the aluminum dihydrogen phosphate gel, stir well to mix, and heat to evaporate the water.

[0019] Furthermore, the mass ratio of the nano-silicon dioxide to the aluminum dihydrogen phosphate colloid is 1-5:1-5.

[0020] The present invention provides a method for preparing high-strength fluorite balls, which is as follows:

[0021] The fluorite powder, epoxy carbon fiber and composite binder are mixed evenly and pressed into shape in a ball press, followed by step-by-step sintering. First, the temperature is increased to 100-150°C at 1-5°C / min and kept for 1-5h, then the temperature is increased to 250-350°C at 5-10°C / min in two stages and kept for 0.5-1h, and finally the mixture is restored to room temperature.

[0022] Furthermore, the pressure during compression molding is 1-100 MPa.

[0023] Beneficial effects of the present invention:

[0024] The invention provides a high-strength fluorite ball. The addition of a composite binder and epoxy-based carbon fibers can improve the balling rate of the fluorite ball and significantly improve its strength. The epoxy-based carbon fibers, aluminum sol and water glass can form an inorganic three-dimensional skeleton. The carboxyl-modified organic silicon resin provides a flexible cross-linking point. The core-shell structured silicon dioxide forms a nano-level anchoring node to fill the pores between the fluorite powder particles, thereby maximizing the inorganic-organic interface bonding energy, maximizing the strength of the fluorite ball, and reducing the breakage rate of the fluorite ball during storage, transportation and use.

[0025] The carboxyl groups in the carboxyl-modified silicone resin can not only coordinate and cross-link with the aluminum ions in the aluminum sol to form a three-dimensional network aluminum-carboxylic acid complex, thereby improving the structural strength of the fluorite balls, but can also react with the epoxy groups on the epoxy carbon fibers to form an anchoring structure, thereby reducing the possibility of carbon fiber slippage under external forces. The aluminum dihydrogen phosphate shell on the surface of the core-shell structured silica can generate aluminum metaphosphate during sintering. The viscous aluminum metaphosphate can wet the gap between the fluorite powder and the nano-silica and form a continuous glass phase network, thereby increasing the density of the fluorite balls and improving their strength. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The reaction scheme of the carboxyl-modified silicone resin prepared in Example 1 is shown in FIG. DETAILED DESCRIPTION

[0027] If the specific conditions are not specified in the examples, the experiments were carried out under conventional conditions or the conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments is not specified, they are all conventional products that can be purchased commercially. The techniques not mentioned in the present invention are all referenced to the prior art. Unless otherwise specified, the following examples and comparative examples are parallel experiments, using the same processing steps and parameters.

[0028] Embodiment 1:

[0029] A high-strength fluorite ball is made from the following raw materials in parts by weight:

[0030] 90 parts of fluorite powder, 5 parts of composite binder, 3 parts of epoxy carbon fiber;

[0031] The composite adhesive is composed of aluminum sol, water glass, carboxyl-modified organic silicon resin and core-shell structured silicon dioxide in a mass ratio of 4:4:3:1.

[0032] The preparation method of epoxy carbon fiber is as follows:

[0033] 5g of silane coupling agent KH-560 was added to a mixed solvent consisting of 90ml of anhydrous ethanol and 10ml of deionized water, followed by ultrasonic treatment for 30min to obtain a mixed solution, 30g of chopped carbon fiber with a length of 0.1-1mm was added to 100ml of concentrated nitric acid, the mixture was heated to reflux and acidified for 10h, filtered out, washed with deionized water and added to the mixed solution, heated to reflux for 24h and then returned to room temperature, filtered, the collected carbon fiber was washed with anhydrous ethanol and dried.

[0034] The preparation method of carboxyl modified silicone resin is as follows:

[0035] Under nitrogen protection, 19.14g of diphenyldihydroxysilane, 30.86g of methyldiethoxysilane and 0.28g of cation exchange resin IR120 were mixed, heated to 100°C for reaction for 18h. After the reaction was completed, the mixture was restored to room temperature for filtration, and the filtrate was distilled under reduced pressure to obtain hydrogen-containing polysiloxane. Under nitrogen protection, 1g of allylmalonic acid was heated to 105°C, and after it melted, 0.01g of chloroplatinic acid was added, and after stirring and mixing, 10g of hydrogen-containing polysiloxane was added. After keeping the temperature for reaction for 8h, low-boiling substances were removed by distillation under reduced pressure. For the reaction route, see Figure 1 .

[0036] The core-shell structured silica is composed of a nano-silicon dioxide core and an aluminum dihydrogen phosphate shell, and its preparation method is as follows:

[0037] Concentrated phosphoric acid was diluted with deionized water to obtain a 6 mol / L phosphoric acid aqueous solution. 7.8 g of aluminum hydroxide was added to 50 ml of the phosphoric acid aqueous solution, and the mixture was heated to reflux and kept warm for 5 h. The heating was stopped, and the mixture was naturally cooled to room temperature to obtain aluminum dihydrogen phosphate gel. 25 g of nano-silicon dioxide was added to the aluminum dihydrogen phosphate gel, and the mixture was stirred thoroughly and heated to evaporate the water.

[0038] The preparation method of the above-mentioned high-strength fluorite ball is as follows:

[0039] The fluorite powder, epoxy carbon fiber and composite binder are mixed evenly and pressed into shape in a ball press at a pressure of 10 MPa. Then, step-by-step sintering is performed. First, the temperature is increased to 120°C at a rate of 1°C / min and kept for 2 hours. Then, the temperature is increased to 300°C at a rate of 5°C / min and kept for 0.5 hours. Finally, the mixture is restored to room temperature.

[0040] Embodiment 2:

[0041] A high-strength fluorite ball is made from the following raw materials in parts by weight:

[0042] 90 parts of fluorite powder, 6 parts of composite binder, 3 parts of epoxy carbon fiber;

[0043] The composite adhesive is composed of aluminum sol, water glass, carboxyl-modified organic silicon resin and core-shell structured silicon dioxide in a mass ratio of 4:4:3:1.

[0044] The preparation method of epoxy carbon fiber, carboxyl modified silicone resin and core-shell structured silica is the same as that of Example 1;

[0045] The preparation method of the above-mentioned high-strength fluorite ball is as follows:

[0046] The fluorite powder, epoxy carbon fiber and composite binder are mixed evenly and pressed into shape in a ball press at a pressure of 10 MPa. Then, step-by-step sintering is performed. First, the temperature is increased to 120°C at a rate of 1°C / min and kept for 2 hours. Then, the temperature is increased to 300°C at a rate of 5°C / min and kept for 0.5 hours. Finally, the mixture is restored to room temperature.

[0047] Embodiment 3:

[0048] A high-strength fluorite ball is made from the following raw materials in parts by weight:

[0049] 90 parts of fluorite powder, 7 parts of composite binder, 3 parts of epoxy carbon fiber;

[0050] The composite adhesive is composed of aluminum sol, water glass, carboxyl-modified organic silicon resin and core-shell structured silicon dioxide in a mass ratio of 4:4:3:1.

[0051] The preparation method of epoxy carbon fiber, carboxyl modified silicone resin and core-shell structured silica is the same as that of Example 1;

[0052] The preparation method of the above-mentioned high-strength fluorite ball is as follows:

[0053] The fluorite powder, epoxy carbon fiber and composite binder are mixed evenly and pressed into shape in a ball press at a pressure of 10 MPa. Then, step-by-step sintering is performed. First, the temperature is increased to 120°C at a rate of 1°C / min and kept for 2 hours. Then, the temperature is increased to 300°C at a rate of 5°C / min and kept for 0.5 hours. Finally, the mixture is restored to room temperature.

[0054] Embodiment 4:

[0055] A high-strength fluorite ball is made from the following raw materials in parts by weight:

[0056] 90 parts of fluorite powder, 8 parts of composite binder, 3 parts of epoxy carbon fiber;

[0057] The composite adhesive is composed of aluminum sol, water glass, carboxyl-modified organic silicon resin and core-shell structured silicon dioxide in a mass ratio of 4:4:3:1.

[0058] The preparation method of epoxy carbon fiber, carboxyl modified silicone resin and core-shell structured silica is the same as that of Example 1;

[0059] The preparation method of the above-mentioned high-strength fluorite ball is as follows:

[0060] The fluorite powder, epoxy carbon fiber and composite binder are mixed evenly and pressed into shape in a ball press at a pressure of 10 MPa. Then, step-by-step sintering is performed. First, the temperature is increased to 120°C at a rate of 1°C / min and kept for 2 hours. Then, the temperature is increased to 300°C at a rate of 5°C / min and kept for 0.5 hours. Finally, the mixture is restored to room temperature.

[0061] Embodiment 5:

[0062] A high-strength fluorite ball is made from the following raw materials in parts by weight:

[0063] 90 parts of fluorite powder, 9 parts of composite binder, 3 parts of epoxy carbon fiber;

[0064] The composite adhesive is composed of aluminum sol, water glass, carboxyl-modified organic silicon resin and core-shell structured silicon dioxide in a mass ratio of 4:4:3:1.

[0065] The preparation method of epoxy carbon fiber, carboxyl modified silicone resin and core-shell structured silica is the same as that of Example 1;

[0066] The preparation method of the above-mentioned high-strength fluorite ball is as follows:

[0067] The fluorite powder, epoxy carbon fiber and composite binder are mixed evenly and pressed into shape in a ball press at a pressure of 10 MPa. Then, step-by-step sintering is performed. First, the temperature is increased to 120°C at a rate of 1°C / min and kept for 2 hours. Then, the temperature is increased to 300°C at a rate of 5°C / min and kept for 0.5 hours. Finally, the mixture is restored to room temperature.

[0068] Embodiment 6:

[0069] A high-strength fluorite ball is made from the following raw materials in parts by weight:

[0070] 90 parts of fluorite powder, 10 parts of composite binder, 3 parts of epoxy carbon fiber;

[0071] The composite adhesive is composed of aluminum sol, water glass, carboxyl-modified organic silicon resin and core-shell structured silicon dioxide in a mass ratio of 4:4:3:1.

[0072] The preparation method of epoxy carbon fiber, carboxyl modified silicone resin and core-shell structured silica is the same as that of Example 1;

[0073] The preparation method of the above-mentioned high-strength fluorite ball is as follows:

[0074] The fluorite powder, epoxy carbon fiber and composite binder are mixed evenly and pressed into shape in a ball press at a pressure of 10 MPa. Then, step-by-step sintering is performed. First, the temperature is increased to 120°C at a rate of 1°C / min and kept for 2 hours. Then, the temperature is increased to 300°C at a rate of 5°C / min and kept for 0.5 hours. Finally, the mixture is restored to room temperature.

[0075] Comparative Example 1:

[0076] The method is basically the same as Example 1, except that the composite binder does not contain aluminum sol.

[0077] Comparative Example 2:

[0078] The method is basically the same as Example 1, except that the composite adhesive does not contain water glass.

[0079] Comparative Example 3:

[0080] The method is basically the same as Example 1, except that the composite adhesive does not contain carboxyl-modified silicone resin.

[0081] Comparative Example 4:

[0082] The method is basically the same as Example 1, except that a commercially available silicone resin (Longsheng Sihai SH-5031P) is used to replace the carboxyl-modified silicone resin in the composite binder.

[0083] Comparative Example 5:

[0084] The method is basically the same as Example 1, except that nano-silica is used instead of core-shell structured silica.

[0085] Performance Testing:

[0086] The fluorite balls (particle size 50 mm) prepared in Examples 1-6 and Comparative Examples 1-5 of the present invention were used as samples to test their drop strength, and the test method was as follows:

[0087] A certain amount of samples were dropped freely onto a steel plate from heights of 5m, 10m and 20m respectively. After 5 repeated drop tests for each group, fluorite pellets with a particle size greater than 10mm were screened out and their mass was accurately weighed. The drop strength was expressed as the percentage of the mass of fluorite pellets with a particle size greater than 10mm to the mass of the sample and calculated according to formula (1);

[0088] S = (m1 / m2) × 100

[0089] S is the drop strength, %, m1 is the mass of fluorite pellets with particle size greater than 10 mm after the test, kg, and m2 is the mass of the original fluorite pellets, kg.

[0090] Each group of experiments was conducted five times, and the data were averaged and recorded in Table 1, which is as follows:

[0091]

[0092] It can be seen from Table 1 above that the fluorite balls prepared by the present invention have high strength. By comparing Examples 1-6, it can be seen that as the amount of the composite binder increases, the drop strength of the fluorite balls shows a trend of first increasing and then decreasing;

[0093] By comparing Example 1 with Comparative Examples 1-3, it can be seen that the addition of aluminum sol, water glass, and carboxyl-modified silicone resin all play a positive role in improving the drop strength of the fluorite ball;

[0094] By comparing Example 1 with Comparative Example 4, it can be seen that the carboxyl-modified silicone resin prepared by the present invention has a greater improvement in the drop strength of fluorite balls than the commercially available silicone resin;

[0095] By comparing Example 1 with Comparative Example 5, it can be seen that the core-shell structured silica prepared by the present invention has a greater improvement in the drop strength of fluorite balls than nano-silicon dioxide.

[0096] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A high-strength fluorite ball, characterized in that: Made from the following raw materials in parts by weight: 85-95 parts of fluorite powder, 5-10 parts of composite binder, 1-5 parts of epoxy carbon fiber; The composite binder is composed of an inorganic binder, a carboxyl-modified silicone resin, and core-shell structured silica; The preparation method of the epoxy carbon fiber is as follows: adding a silane coupling agent KH-560 to a mixed solvent consisting of anhydrous ethanol and deionized water, then subjecting the mixed solution to ultrasonic treatment, acidifying the carbon fiber with concentrated nitric acid and adding the mixed solution, heating the mixture to reflux for 10-30 hours and then returning to room temperature, filtering, washing the collected carbon fiber and drying it; The mass ratio of the inorganic binder, carboxyl-modified silicone resin and core-shell structured silica is 5-10:1-5:1-2; The inorganic binder is composed of aluminum sol and water glass in a mass ratio of 1-5:1-5; The core-shell structured silica consists of a nano-silicon dioxide core and an aluminum dihydrogen phosphate shell.

2. The high-strength fluorite ball according to claim 1, characterized in that: The preparation method of the carboxyl-modified silicone resin is as follows: Under nitrogen protection, diphenyldihydroxysilane, methyldiethoxysilane and cation exchange resin are mixed, heated to 90-100°C and reacted for 10-30 hours. After the reaction is completed, the filtrate is filtered and the filtrate is distilled under reduced pressure to obtain hydrogen-containing polysiloxane. Under nitrogen protection, allylmalonic acid is heated to 105-110°C, chloroplatinic acid is added after it is melted, and the hydrogen-containing polysiloxane is added after stirring and mixing. The reaction is kept warm for 1-10 hours and then distilled under reduced pressure.

3. The high-strength fluorite ball according to claim 1, characterized in that: The preparation method of the core-shell structured silica is as follows: Add aluminum hydroxide to the phosphoric acid aqueous solution, heat to reflux and keep warm for 1-10 hours, stop heating, cool naturally to room temperature to obtain aluminum dihydrogen phosphate gel, add nano-silicon dioxide to the aluminum dihydrogen phosphate gel, stir well to mix, and heat to evaporate the water.

4. The high-strength fluorite ball according to claim 3, characterized in that: The mass ratio of the nano silicon dioxide to the aluminum dihydrogen phosphate gel is 1-5:1-5.

5. A method for preparing high-strength fluorite balls as claimed in any one of claims 1 to 4, characterized in that: The details are as follows: The fluorite powder, epoxy carbon fiber and composite binder are mixed evenly and pressed into shape in a ball press, followed by step-by-step sintering. First, the temperature is increased to 100-150°C at 1-5°C / min and kept for 1-5h, then the temperature is increased to 250-350°C at 5-10°C / min in two stages and kept for 0.5-1h, and finally the mixture is restored to room temperature.

6. The method for preparing high-strength fluorite balls according to claim 5, characterized in that: The pressure during compression molding is 1-100 MPa.

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