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Method for removing porcelain by hydrofluoric acid and co-producing white carbon black

A technology of hydrofluoric acid and white carbon black, applied in the direction of silicon dioxide, silicon oxide, etc., can solve the problems that the enamel cannot be completely removed, cannot be recycled and reused, and the blank is easy to deform, so as to achieve reasonable acid utilization and low production cost , the effect of short reaction time

Inactive Publication Date: 2009-09-16
TIANJIN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The mechanical method does not remove the porcelain uniformly, the enamel cannot be completely removed, and the blank is easily deformed when the thin-walled product is impacted, resulting in the blank being scrapped and unable to be recycled.

Method used

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  • Method for removing porcelain by hydrofluoric acid and co-producing white carbon black
  • Method for removing porcelain by hydrofluoric acid and co-producing white carbon black

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0018] (1) Taking gray cast iron enamel as an example, the formula of gray cast iron enamel (w%)

[0019]

[0020] In the enamel composition, SiO 2 It is a matrix agent that can form the skeleton of enamel. SiO 2 At least a certain content in the composition of enamel raw materials can maintain the structure of enamel. In most enamel materials SiO 2 The content is more than 50wt.%. Immerse the defective cast iron enamel in a reaction kettle filled with a hydrofluoric acid aqueous solution with a mass fraction of 85%, heat it indirectly with water vapor, and react at 70°C for 2 hours, and silicon tetrafluoride gas will be generated. The responses are:

[0021] Na 2 O+2HF=2NaF+H 2 o

[0022] K 2 O+2HF=2KF+H 2 o

[0023] SiO 2 +4HF=SiF 4 ↑+H 2 o

[0024] SiF 4 +2HF=H 2 SiO 6

[0025] CaO+2HF=CaF 2 ↓+H 2 o

[0026] Al 2 o 3 +6HF=2AIF 3 +3H 2 o

[0027] TiO 2 +6HF=H 2 TiF 6 +2H 2 o

[0028] B 2 o 3 +6HF=2BF 3 +3H 2 o

[0029] In the reaction,...

Embodiment 2

[0044] The method that hydrofluoric acid removes porcelain and co-produces white carbon black, comprises the steps:

[0045](1) Immerse the cast iron enamel defective product in the reaction kettle that filled the hydrofluoric acid aqueous solution of 75% by mass fraction, indirect heating, at 80 ℃, react 1h, have silicon tetrafluoride gas to generate, described reaction Filtrate the liquid in the kettle, re-input the filtrate into the reaction kettle, wash the remaining substances with 15% sodium hydroxide aqueous solution, reclaim the cast iron, and further process the waste residue;

[0046] (2) Use ammonia water with a mass fraction of 25% to simultaneously absorb silicon tetrafluoride gas and volatilized hydrogen fluoride gas with a molar ratio of 1:2, the amount of ammonia water added is 1.2 times the theoretical amount, and 30% fluorine The ammonium chloride aqueous solution absorbs silicon tetrafluoride gas that has not been absorbed, and the solution is heated to boil...

Embodiment 3

[0049] The method for hydrofluoric acid porcelain removal and co-production of white carbon black is characterized in that it comprises the steps:

[0050] (1) Immerse the cast iron enamel defective product in the reactor of the hydrofluoric acid aqueous solution of 95% in full bloom by mass fraction, indirect heating, at 60 ℃, react 3h, have silicon tetrafluoride gas to generate, described reaction Filtrate the liquid in the kettle, re-input the filtrate into the reaction kettle, wash the rest of the material with 10% sodium hydroxide aqueous solution, recover the cast iron, and further process the waste residue;

[0051] (2) Use ammonia water with a mass fraction of 20% to simultaneously absorb silicon tetrafluoride gas and volatilized hydrogen fluoride gas with a molar ratio of 1:2, the amount of ammonia water added is 1.5 times the theoretical amount, and 20% fluorine The ammonium chloride aqueous solution absorbs silicon tetrafluoride gas that has not been absorbed, and t...

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Abstract

The invention discloses a method for removing porcelain by hydrofluoric acid and co-producing white carbon black, comprising the following steps: (1) immersing cast iron enamel defective products in a reaction vessel with hydrofluoric acid water solution, carrying out the heating reaction, generating silicon tetrafluoride gas, filtering, re-inputting filtrate into the reaction vessel, washing other substances by sodium hydroxide water solution, recovering cast iron and further processing waste residues; (2) using ammonia water to simultaneously absorb the silicon tetrafluoride gas and hydrogen fluoride gas, using ammonium fluoride water solution to absorb the silicon tetrafluoride gas which is not absorbed and heating, thereby obtaining ammonium fluosilicate solution; (3) using ammonia water to regulate pH for reaction, generating sediment, filtering, separating, acidifying a filter cake by sulfuric acid, aging, filtering, washing by water and drying, thereby obtaining the white carbon black. The recovery rate can be more than 90 percent by using the method to process the cast iron enamels, and the method has the advantages of short reaction time, reasonable utilization of the acid, high utilization rate of raw materials and low production cost.

Description

technical field [0001] The invention relates to a method for removing defective enamel coating on the surface of cast iron and using the product to produce white carbon black, in particular to a method for hydrofluoric acid removal of enamel and co-production of white carbon black. Background technique [0002] The enamel preparation process includes many processes, and the quality of the enamel layer depends on many factors. Even strict control of each production process cannot completely avoid defective products in the production of enamel, that is, defective enamel products. For these defective products, the enamel on the surface of the enamel blank must be completely removed before re-coating. [0003] For the devitrification treatment of enamel products, mechanical methods such as sandblasting, shot blasting and thermal expansion and contraction are usually used. The mechanical method does not remove the porcelain uniformly, cannot completely remove the enamel, and the...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B33/12
Inventor 王富民白英张旭斌蔡旺峰辛峰
Owner TIANJIN UNIV
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