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Method and apparatus for preparing fumed silica from coal gangue

A technology of fumed silica and coal gangue, applied in the direction of silica, silicon oxide, etc., can solve the problems of low efficiency and non-reactivity, etc., and achieve the effects of simple process flow, guaranteed operation safety, and saved operation time

Inactive Publication Date: 2015-12-02
LIUPANSHUI NORMAL UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0007] Since coal gangue has high lattice energy and almost no reactivity, if it is directly upgraded and utilized without treatment, the efficiency is very low

Method used

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  • Method and apparatus for preparing fumed silica from coal gangue
  • Method and apparatus for preparing fumed silica from coal gangue
  • Method and apparatus for preparing fumed silica from coal gangue

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0099] (1) Preparation of wave absorbing agent

[0100] Immerse chromium trioxide with 3.0mol / L nitric acid aqueous solution for the first time in a 70°C constant temperature water bath for 8 hours, and then soak it with 2.0% ferric nitrate aqueous solution for 12 hours at 25°C for the second time, age for 18 hours, and finally Put it into a muffle furnace for calcination, first keep the temperature at 110 ℃ for 30 minutes, then calcine at 1200 ℃ for 2 hours, cool naturally, and sieve to obtain the finished product of 10-mesh wave absorbing agent.

[0101] (2) Fumed silica preparation conditions

[0102] Pass the crushed coal gangue through a 70-mesh sieve and roast it in a muffle furnace at 750°C for 1.5 hours, and then react with 40% hydrofluoric acid at a ratio of 1g:4mL in a microwave field with a gauge pressure of 0.6Mpa. The temperature was 140°C. The outlet flow rate of silicon tetrafluoride gas is controlled at 3200kg / (m 3 Absorbent﹒ h), the water vapor is in exces...

Embodiment 2

[0104] (1) Preparation of wave absorbing agent

[0105] Immerse chromium trioxide with 3.0 mol / L nitric acid aqueous solution for the first time in a constant temperature water bath at 80°C for 9 hours, and for the second time at 25°C with 2.0% ferric nitrate aqueous solution for 13 hours, age for 20 hours, and finally Put it into a muffle furnace for calcination, first keep the temperature at 110 ℃ for 30 minutes, then calcine at 1200 ℃ for 2 hours, cool naturally, and sieve to obtain the finished product of 10-mesh wave absorbing agent.

[0106] (2) Fumed silica preparation conditions

[0107] Pass the crushed coal gangue through an 80-mesh sieve and roast it in a muffle furnace at 750°C for 1.5 hours, and then react with 40% hydrofluoric acid at a ratio of 1g:4mL in a microwave field with a gauge pressure of 0.7Mpa. The temperature was 140°C. The outlet flow rate of silicon tetrafluoride gas is controlled at 3600kg / (m 3 Absorbent﹒ h), the water vapor is in excess of 1.7...

Embodiment 3

[0109] (1) Preparation of wave absorbing agent

[0110] Immerse chromium trioxide in a 90°C constant temperature water bath for 10 hours for the first time with 3.0 mol / L nitric acid aqueous solution, and for the second time at 25°C with 2.0% ferric nitrate aqueous solution for 14 hours, age for 22 hours, and finally Put it into a muffle furnace for calcination, first keep the temperature at 110 ℃ for 30 minutes, then calcine at 1200 ℃ for 2 hours, cool naturally, and sieve to obtain the finished product of 20-mesh wave absorbing agent.

[0111] (2) Fumed silica preparation conditions

[0112] Pass the crushed coal gangue through a 100-mesh sieve and roast it in a muffle furnace at 800°C for 1.5 hours, and then react with 40% hydrofluoric acid at a ratio of 1g:5mL in a microwave field with a gauge pressure of 0.8Mpa. The temperature is 150°C. The outlet flow rate of silicon tetrafluoride gas is controlled at 4000kg / (m 3 Absorbent﹒ h), the water vapor is in excess of 2.0 ac...

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Abstract

The invention discloses a method and an apparatus for preparing fumed silica from coal gangue. The method comprises: performing pressurized reaction, in microwave fields, on activated coal gangue powder and hydrofluoric acid, converging the generated silicon tetrafluoride gas with water vapor to obtain a mixture and introducing the mixture into a micorwave-absorbing agent packed column under microwave irradiation, and performing high-temperature pyrohydrolysis reaction on the mixture to generate gas silicon dioxide and hydrogen fluoride; performing shock chilling, gathering, separating, acid-removing and purging on the generated gas silicon dioxide and hydrogen fluoride as well as unreacted water vapor to prepare a fumed silica product; separating the hydrogen fluoride gas and the water vapor from a cyclone separator and the top of an acid removing furnace, and adding the water to prepare hydrofluoric acid for recycling, wherein the fumed silica product can be used as a thickening agent, a rubber reinforcing agent and a washing assistant agent, and the like; by-products are aluminum fluoride, iron fluoride and magnesium fluoride and the like; the microwave-absorbing agent in the present invention can significantly improve the direct hydrolysis efficiency of silicon tetrafluoride; the pressurized microwave reaction can significantly increase the reaction rate and conversion rate of silicon dioxide and hydrofluoric acid; and the microwave-absorbing agent is recycled and easy to regenerate, and has a high utilization rate, a simple process and low preparation cost.

Description

technical field [0001] The invention belongs to the technical field of coal gangue upgrading and utilization, and in particular relates to a method and a device for preparing fumed silicon dioxide from coal gangue. Background technique [0002] Fumed silica is a white, non-toxic, odorless, amorphous inorganic fine chemical product with a particle size of 7-40 nanometers and a specific surface area of ​​70-400m 2 / g, is one of the extremely important high-tech ultrafine inorganic new materials. Due to the small particle size, fumed silica has large specific surface area, strong surface adsorption force, large surface energy, high chemical purity, good dispersion performance, and has specific properties in terms of thermal resistance and electrical resistance. , Reinforcement, thickening and thixotropy have unique characteristics in many disciplines and fields and play an irreplaceable role. [0003] Fumed silica is usually produced by chemical vapor deposition, which is gen...

Claims

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Application Information

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IPC IPC(8): C01B33/18
Inventor 连明磊孔德顺宋说讲李志卢香宇
Owner LIUPANSHUI NORMAL UNIV
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