A method of decontaminating chrome corundum and producing refractory bricks

Abstract

The application discloses a method for detoxifying chrome corundum and producing refractory bricks, and comprises the following steps: step one, crushing chrome corundum into different specifications, and then placing the chrome corundum in a leaching solution; filtering, cleaning and drying the chrome corundum after soaking to obtain detoxified chrome corundum; step two, adding the detoxified chrome corundum into electrically fused zircon mullite and a binder phosphoric acid, stirring and uniformly mixing, then placing, adding a binder aluminum dihydrogen phosphate and mixing, and then pressing and forming into blocky chrome corundum; and step three, high-temperature sintering the blocky chrome corundum after pressing and forming to obtain chrome corundum refractory bricks. The application has the following beneficial effects: the application leaches free hexavalent chromium in the chrome corundum by using a reducing agent, water and acid, improves the quality of the chrome corundum, and obtains more environmentally-friendly chrome corundum, so that the quality of the refractory bricks is higher; and the application can efficiently and at low cost treat the chrome corundum, convert the chrome corundum into high-value and high-performance refractory bricks, and realize the maximum economic value of the chrome corundum.

Description

Technical Field

[0001] This invention belongs to the field of new materials technology. More specifically, this invention relates to a method for detoxifying chromium corundum and producing refractory bricks. Background Technology

[0002] Chromium corundum is an excellent high-temperature refractory material. Its high-temperature resistance and corrosion resistance are irreplaceable by traditional alumina and magnesium oxide materials. At the same time, chromium corundum refractories are irreplaceable in many industries that require refractory materials.

[0003] However, since chromium corundum contains a small amount of toxic and harmful hexavalent chromium, it is prone to environmental pollution. According to the latest national hazardous waste management system, chromium corundum is classified as hazardous waste. Now, there is a need for a technical solution that can harmlessly treat chromium corundum and transform it into usable materials to ensure that chromium corundum has more environmentally friendly and safe properties. Summary of the Invention

[0004] One object of the present invention is to solve at least the above-mentioned problems and / or defects, and to provide at least the advantages described below.

[0005] To achieve these objectives and other advantages according to the present invention, a method for detoxifying chromium corundum and producing refractory bricks is provided, comprising:

[0006] Step 1: Crush chromium corundum into different sizes, then place it in the leaching solution to leach out free hexavalent chromium. Filter, wash and dry the soaked chromium corundum to obtain detoxified chromium corundum.

[0007] Step 2: Add fused zircon mullite and binder phosphate to the detoxified chromium corundum, stir and mix well, let stand for a period of time, then add binder aluminum dihydrogen phosphate and mix, and press into block chromium corundum.

[0008] Step 3: The pressed and shaped chromium corundum blocks are sintered at high temperature to obtain chromium corundum refractory bricks.

[0009] Preferably, in step one, the particle size of the chromium corundum is 5~1mm, or 100~400 mesh.

[0010] Preferably, in step one, the leaching solution is one of a reducing agent, water, or an acid. The reducing agent can be hydrazine hydrate, and the acid can be one or more of nitric acid, hydrochloric acid, and sulfuric acid.

[0011] Preferably, in step one, the leaching process is as follows: at room temperature, a reducing agent, water, or acid is taken and chromium corundum is added to it at a mass ratio of 1:1, and the mixture is left to stand for 24 hours to leach out free hexavalent chromium.

[0012] Preferably, in step two, the mass ratio of chromium corundum to fused zirconium mullite is 4~16:1, and the amount of phosphate binder added is 2.5%~5% of the total mass of chromium corundum and fused zirconium mullite.

[0013] Preferably, in step two, the particle size of the fused zircon mullite is 0~3mm.

[0014] Preferably, in step three, the amount of aluminum dihydrogen phosphate binder added is 1% to 2.5% of the total mass of chromium corundum, fused zirconium mullite, and binder phosphate.

[0015] Preferably, in step three, the high-temperature sintering temperature is 1400℃~1600℃, and the sintering time is 20h~25h.

[0016] Preferably, before step two, the detoxified chromium corundum is modified, by means of:

[0017] S1. Immerse the detoxified chromium corundum in a mixture of 3% nitric acid and 2% hydrofluoric acid at 15-30°C for 5-10 minutes. Then remove the detoxified chromium corundum, clean it, and dry it.

[0018] S2. Soak the dried detoxified chromium corundum in a 40g / L tin chloride acidic solution for 8-16 minutes at room temperature. Then remove the detoxified chromium corundum, place it in an acetone solution for ultrasonic cleaning, and dry it.

[0019] S3. Soak the dried detoxified chromium corundum in 0.15 g / L palladium chloride acidic solution at 40~50℃ for 8~16 min, then remove the detoxified chromium corundum, clean and dry it.

[0020] S4. Immerse the dried detoxified chromium corundum in a chemical plating solution containing 8 g / L NiSO4, 30 g / L reducing agent, 15 g / L CH3COONa, 25 g / L sodium citrate, and 8 ml / L lactic acid. Immerse at 80~90℃ for 30~45 min. After immersion, remove the corundum to obtain modified detoxified chromium corundum with nickel plating on the surface.

[0021] Preferably, after modifying the detoxified chromium corundum, in step two, an additional 4-6% by weight of nano-hexagonal boron nitride and nano-silica are added, with the mass ratio of nano-hexagonal boron nitride to nano-silica being 2:1.

[0022] The present invention has at least the following beneficial effects:

[0023] (1) This invention improves the quality of chromium corundum by using reducing agents, water, and acid leaching to detoxify chromium corundum, resulting in more environmentally friendly chromium corundum, thereby making the refractory bricks of higher quality.

[0024] (2) This invention can process chromium corundum in an efficient and low-cost manner, transforming chromium corundum into high-value and high-performance refractory bricks, thereby maximizing its economic value.

[0025] (3) The present invention also improves the corrosion resistance of chromium corundum refractory bricks by modifying chromium corundum and adding nano-hexagonal boron nitride and nano-silica before calcination.

[0026] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Detailed Implementation

[0027] The present invention will now be described in further detail so that those skilled in the art can implement it based on the description.

[0028] Example 1

[0029] A method for detoxifying chromium corundum and producing refractory bricks includes:

[0030] Step 1: Crush 100kg of chromium corundum into particles with a diameter of 3mm, then add the chromium corundum particles to 100kg of water and soak for 24 hours to leach out free hexavalent chromium. Filter, wash and dry the soaked chromium corundum to obtain detoxified chromium corundum.

[0031] Step 2: Add 25 kg of fused zircon mullite with a particle size of 2 mm to the detoxified chromium corundum, then add 3.125 kg of phosphoric acid, stir evenly and let stand for 6 hours, then add 1.28 kg of aluminum dihydrogen phosphate for mixing and pressing into block chromium corundum.

[0032] Step 3: The pressed and shaped chromium corundum blocks are sintered in a high-temperature furnace at 1400℃ for 24 hours to obtain chromium corundum refractory bricks.

[0033] Example 2

[0034] A method for detoxifying chromium corundum and producing refractory bricks includes:

[0035] Step 1: Crush 100kg of chromium corundum into particles with a diameter of 2mm, then add the chromium corundum particles to 100kg of hydrazine hydrate and soak for 24 hours to leach out free hexavalent chromium. Filter, wash and dry the soaked chromium corundum to obtain detoxified chromium corundum.

[0036] Step 2: Add 6.25 kg of fused zircon mullite with a particle size of 2 mm to the detoxified chromium corundum, then add 3.187 kg of phosphoric acid, stir evenly and let stand for 6 hours, then add 1.09 kg of aluminum dihydrogen phosphate for mixing and pressing into block chromium corundum.

[0037] Step 3: The pressed and shaped chromium corundum blocks are sintered in a high-temperature furnace at 1500℃ for 23 hours to obtain chromium corundum refractory bricks.

[0038] Example 3

[0039] A method for detoxifying chromium corundum and producing refractory bricks includes:

[0040] Step 1: Crush 100kg of chromium corundum into particles with a diameter of 4mm. Then, add the chromium corundum particles to 100kg of 30% hydrochloric acid and soak for 24 hours to leach out free hexavalent chromium. Filter, wash and dry the soaked chromium corundum to obtain detoxified chromium corundum.

[0041] Step 2: Add 6.25 kg of fused zircon mullite with a particle size of 2 mm to the detoxified chromium corundum, then add 4.25 kg of phosphoric acid, stir evenly and let stand for 6 hours, then add 2.21 kg of aluminum dihydrogen phosphate for mixing and pressing into block chromium corundum.

[0042] Step 3: The pressed and shaped chromium corundum blocks are sintered in a high-temperature furnace at 1600℃ for 24 hours to obtain chromium corundum refractory bricks.

[0043] Example 4

[0044] Step 1: Crush 100kg of chromium corundum into particles with a diameter of 3mm, then add the chromium corundum particles to 100kg of water and soak for 24 hours to leach out free hexavalent chromium. Filter, wash and dry the soaked chromium corundum to obtain detoxified chromium corundum.

[0045] Before step two, the detoxified chromium corundum is modified as follows:

[0046] S1. Immerse the detoxified chromium corundum in a mixture of 3% nitric acid and 2% hydrofluoric acid at 15-30°C for 5-10 minutes. Then remove the detoxified chromium corundum, clean it, and dry it.

[0047] S2. Soak the dried detoxified chromium corundum in a 40g / L tin chloride acidic solution for 8-16 minutes at room temperature. Then remove the detoxified chromium corundum, place it in an acetone solution for ultrasonic cleaning, and dry it.

[0048] S3. Soak the dried detoxified chromium corundum in 0.15 g / L palladium chloride acidic solution at 40~50℃ for 8~16 min, then remove the detoxified chromium corundum, clean and dry it.

[0049] S4. Immerse the dried detoxified chromium corundum in a chemical plating solution containing 8 g / L NiSO4, 30 g / L reducing agent, 15 g / L CH3COONa, 25 g / L sodium citrate, and 8 ml / L lactic acid. Immerse at 80~90℃ for 30~45 min. After immersion, remove the corundum to obtain modified detoxified chromium corundum with nickel plating on the surface.

[0050] Step 2: Add 25 kg of fused zircon mullite with a particle size of 2 mm to the modified and detoxified chromium corundum with nickel plating on the surface, then add 3.125 kg of phosphoric acid, stir evenly and let stand for 6 hours, then add 1.28 kg of aluminum dihydrogen phosphate for mixing and pressing into block chromium corundum.

[0051] Step 3: The pressed and shaped chromium corundum blocks are sintered in a high-temperature furnace at 1400℃ for 24 hours to obtain chromium corundum refractory bricks.

[0052] Example 5

[0053] Step 1: Crush 100kg of chromium corundum into particles with a diameter of 3mm, then add the chromium corundum particles to 100kg of water and soak for 24 hours to leach out free hexavalent chromium. Filter, wash and dry the soaked chromium corundum to obtain detoxified chromium corundum.

[0054] Before step two, the detoxified chromium corundum is modified as follows:

[0055] S1. Immerse the detoxified chromium corundum in a mixture of 3% nitric acid and 2% hydrofluoric acid at 15-30°C for 5-10 minutes. Then remove the detoxified chromium corundum, clean it, and dry it.

[0056] S2. Soak the dried detoxified chromium corundum in a 40g / L tin chloride acidic solution for 8-16 minutes at room temperature. Then remove the detoxified chromium corundum, place it in an acetone solution for ultrasonic cleaning, and dry it.

[0057] S3. Soak the dried detoxified chromium corundum in 0.15 g / L palladium chloride acidic solution at 40~50℃ for 8~16 min, then remove the detoxified chromium corundum, clean and dry it.

[0058] S4. Immerse the dried detoxified chromium corundum in a chemical plating solution containing 8 g / L NiSO4, 30 g / L reducing agent, 15 g / L CH3COONa, 25 g / L sodium citrate, and 8 ml / L lactic acid. Immerse at 80~90℃ for 30~45 min. After immersion, remove the corundum to obtain modified detoxified chromium corundum with nickel plating on the surface.

[0059] Step 2: Add 25 kg of fused zircon mullite with a particle size of 2 mm, 4 kg of nano hexagonal boron nitride and 2 kg of nano silicon dioxide to the modified and detoxified chromium corundum with nickel plating on the surface, then add 3.125 kg of phosphoric acid, stir evenly and let stand for 6 hours, then add 1.28 kg of aluminum dihydrogen phosphate for mixing and pressing into block chromium corundum.

[0060] Step 3: The pressed and shaped chromium corundum blocks are sintered in a high-temperature furnace at 1400℃ for 24 hours to obtain chromium corundum refractory bricks.

[0061] Comparative Example 1

[0062] The difference between this comparative example and Example 1 is that step two is as follows: 25 kg of fused zircon mullite with a particle size of 2 mm, 4 kg of nano-hexagonal boron nitride, and 2 kg of nano-silica are added to the detoxified chromium corundum. Then, 3.125 kg of phosphoric acid is added, stirred evenly, and left to stand for 6 hours. Then, 1.28 kg of aluminum dihydrogen phosphate is added for mixing and pressing into block chromium corundum. The remaining steps are the same as in the example.

[0063] The corrosion resistance of the refractory bricks prepared in Examples 1-5 and Comparative Example 1 was tested. The method involved immersing sampled bricks in 10% hydrogen chloride solution, 10% sodium hydroxide solution, 10% sodium chloride solution, and 10% sodium sulfate solution, respectively, for 8 months. After immersion, their strength was tested. The corrosion coefficient was calculated as: strength of the corroded brick / strength after immersion in water at the same age. The test results are shown in Table 1.

[0064] Table 1

[0065]

[0066] As can be seen from Table 1, in Example 4, the corrosion resistance of the chromium corundum was improved by surface nickel plating, which improved the corrosion resistance of the chromium corundum. The corrosion resistance of the refractory bricks obtained in the end was improved compared with that in Examples 1-3. In Example 5, in addition to the addition of nano-hexagonal boron nitride and nano-silica, nano-hexagonal boron nitride and nano-silica were added to further improve the overall corrosion resistance of the refractory bricks. The corrosion resistance of the refractory bricks obtained in the end was significantly improved compared with that in Examples 1-3. In Comparative Example 1, only nano-hexagonal boron nitride and nano-silica were added. The corrosion resistance of the refractory bricks was also improved, but the effect was not significant.

[0067] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details.

Claims

1. A method for preparing detoxifying chromium corundum refractory bricks, characterized in that, Includes the following steps: Step 1: Crush chromium corundum into different sizes, then place it in the leaching solution to leach out free hexavalent chromium. After leaching, filter, wash and dry the chromium corundum to obtain detoxified chromium corundum. Step 2: Add fused zircon mullite and binder phosphate to the detoxified chromium corundum, stir and mix well, let stand for a period of time, then add binder aluminum dihydrogen phosphate and mix, and press into block chromium corundum. Step 3: The pressed and shaped block chromium corundum is sintered at high temperature to obtain chromium corundum refractory bricks. Before step two, the detoxified chromium corundum is modified as follows: S1. Immerse the detoxified chromium corundum in a mixture of 3% nitric acid and 2% hydrofluoric acid at 15-30°C for 5-10 minutes. Then remove the detoxified chromium corundum, clean it, and dry it. S2. Soak the dried detoxified chromium corundum in a 40g / L tin chloride acidic solution for 8-16 minutes at room temperature. Then remove the detoxified chromium corundum, place it in an acetone solution for ultrasonic cleaning, and dry it. S3. Soak the dried detoxified chromium corundum in 0.15 g / L palladium chloride acidic solution at 40~50℃ for 8~16 min, then remove the detoxified chromium corundum, clean and dry it. S4. Immerse the dried detoxified chromium corundum in a chemical plating solution containing 8 g / L NiSO4, 30 g / L reducing agent, 15 g / L CH3COONa, 25 g / L sodium citrate, and 8 ml / L lactic acid. Immerse at 80~90℃ for 30~45 min. After immersion, remove the corundum to obtain modified detoxified chromium corundum with nickel plating on the surface. After modifying the detoxified chromium corundum, in step two, an additional 4-6% by weight of nano-hexagonal boron nitride and nano-silica are added, with a mass ratio of nano-hexagonal boron nitride to nano-silica of 2:

1.

2. The preparation method of the detoxifying chromium corundum refractory brick as described in claim 1, characterized in that, In step one, the particle size of the chromium corundum is 1~5mm or 100~400 mesh.

3. The preparation method of the detoxifying chromium corundum refractory brick as described in claim 1, characterized in that, In step one, the leaching solution is one of a reducing agent, water, or an acid. The reducing agent can be hydrazine hydrate, and the acid can be one or more of nitric acid, hydrochloric acid, and sulfuric acid.

4. The preparation method of the detoxifying chromium corundum refractory brick as described in claim 1, characterized in that, In step one, the leaching process is as follows: at room temperature, take a reducing agent, water, or acid, add chromium corundum to it at a mass ratio of 1:1, and let it stand for 24 hours to leach out free hexavalent chromium.

5. The method for preparing detoxifying chromium corundum refractory bricks as described in claim 1, characterized in that, In step two, the mass ratio of chromium corundum to fused zirconium mullite is 4~16:1, and the amount of phosphate binder added is 2.5%~5% of the total mass of chromium corundum and fused zirconium mullite.

6. The method for preparing detoxifying chromium corundum refractory bricks as described in claim 1, characterized in that, In step two, the particle size of the fused zircon mullite is 0~3mm.

7. The method for preparing detoxifying chromium corundum refractory bricks as described in claim 1, characterized in that, In step two, the amount of aluminum dihydrogen phosphate binder added is 1% to 2.5% of the total mass of chromium corundum, fused zirconium mullite, and binder phosphate.

8. The method for preparing detoxifying chromium corundum refractory bricks as described in claim 1, characterized in that, In step three, the high-temperature sintering temperature is 1400℃~1600℃, and the sintering time is 20h~25h.

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