CN111302470A - A kind of defluorination precipitant and preparation method thereof and method for defluorination of polluted acid waste water using the same - Google Patents

Abstract

The invention relates to a defluorination precipitant, a preparation method thereof, and a method for defluorination of polluted acid waste water by using the same, belonging to the technical field of waste water and waste liquid treatment and reuse. The defluorination precipitant provided by the invention comprises an oxygen-containing organosilicon compound and thiourea in a molar ratio of 0.01:1-100:1. The silicon atom and imino group contained in the fluorine-removing precipitant of the present invention respectively provide reaction sites for "nucleophilic substitution" and "ionic bonding" with fluoride ions, and generate hydrophobic fluorine-containing precipitates through hydrolysis and polycondensation reactions. And the solution is precipitated to reduce the concentration of fluoride in the polluted acid wastewater to below 10mg/L, and the reaction process is not disturbed by coexisting ions in the polluted acid wastewater, and has the ability to remove fluorine with high selectivity. Compared with the conventional fluorine removal method, the fluorine-containing precipitate produced after defluorination is reduced by more than 96%, and the reuse of the fluorine-containing precipitate and the purified polluted acid wastewater can be realized.

Description

A kind of defluorination precipitant and its preparation method and its use for defluorination of polluted acid wastewater Methods

technical field

The invention relates to a defluorination precipitant, a preparation method thereof, and a method for defluorination of polluted acid waste water by using the same, belonging to the technical field of waste water and waste liquid treatment and reuse.

Background technique

Polluted acid wastewater mainly comes from industries such as non-ferrous metal smelting and sulfur concentrate acid production, and contains relatively high concentrations of sulfuric acid (50-200g/L) and fluoride (200-3000mg/L). For the removal of fluorine in polluted acid wastewater, the industry generally adopts the lime milk neutralization method, that is, adding lime milk to the wastewater, so that the fluoride ions are precipitated as CaF ₂ and removed. Precipitation, but also need to add iron salts, flocculants and other additives. However, since the strong acid solution contains 50-180g/L sulfate ions, it will consume a large amount of calcium ions. To ensure the defluorination efficiency, it is necessary to further increase the usage of lime milk; It has greatly increased the difficulty of solid-liquid separation. According to field research, each cubic meter of wastewater containing 50g/LH ₂ SO ₄ will produce 50-100Kg of gypsum slag. In addition to fluorine, these gypsum slag also contains Heavy metal ions such as zinc, lead, arsenic, iron, copper and other heavy metal ions with different concentration levels are hazardous solid wastes, and enterprises still need to invest a high cost for their safe disposal. If they are disposed of improperly, there is a risk of secondary pollution. In addition, the neutralization and defluorination method of lime milk leads to the inability to reuse valuable resources, resulting in waste of resources.

Some other fluoride removal methods, such as adsorption, ion exchange, reverse osmosis, etc., are only suitable for drinking water or surface water with near neutral pH (5-8) and low concentration of fluoride (<10mg/L). Removal, not suitable for effective removal of fluoride in wastewater with strong acidity, high fluoride concentration (>100mg/L) and complex composition.

So far, for the removal of fluoride in polluted acid wastewater, there is still no technology that can solve the shortcomings of existing fluoride removal methods such as large amount of hazardous solid waste, slow sedimentation, difficult dehydration, and inability to recover useful resources.

SUMMARY OF THE INVENTION

In order to solve the technical problems in the above-mentioned background technology, the present invention provides a defluorination precipitant, a preparation method thereof, and a method for defluorination of polluted acid wastewater by using the same.

The technical solution of the present invention to solve the above technical problems is as follows: a defluorination precipitant, comprising an oxygen-containing organosilicon compound and thiourea in a molar ratio of 0.01:1-100:1.

The beneficial effects of the defluorination precipitant provided by the invention are:

The silicon atom and imino group contained in the fluorine-removing precipitant provided by the present invention respectively provide "nucleophilic substitution" and "ionic bonding" reaction sites with obligate action with fluoride ions, and generate fluorine-containing precipitates through hydrolysis and polycondensation reactions. , and a solution was precipitated. The fluoride removal process is basically free from the interference of coexisting ions in the polluted acid wastewater, and it does not need to adjust the acidity. and efficient removal.

Since the fluorine-removing precipitant provided by the present invention has a certain number of hydrophobic groups, the generated fluorine-containing precipitate has a certain hydrophobicity, and the solid-liquid separation is easy to carry out. The agent only has a precipitation reaction with fluoride ions in the polluted acid wastewater, and the amount of fluorine-containing precipitation produced is extremely small.

In addition, the separated fluorine-containing precipitate is another new material with higher purity, which can be recycled as a resource. The polluted acid wastewater after defluorination can also be reused in the production process. Therefore, the use of the defluorination precipitation of the present invention can overcome the disadvantages of producing a large amount of hazardous solid wastes after the treatment of the existing polluted acid wastewater, difficult dehydration, and inability to recover useful resources, and almost no waste is generated in the entire defluorination process using the agent, It can not only save production costs for enterprises, but also generate excellent economic and social benefits through the resource utilization of valuable components.

On the basis of the above technical solutions, the present invention can also be improved as follows.

Further, the oxygen-containing organosilicon compound includes methyltriacetoxysilane, methoxytrichlorosilane, dimethoxydichlorosilane, phenyltrichlorosilane, methoxysilane, ethoxysilane, methyl Any one or more of silanol, butadienyltriethoxysilane, potassium methylsiliconate, vinyltriethoxysilane and γ-aminopropyltriethoxysilane.

The present invention solves the above-mentioned technical problems and also provides the following technical scheme: a preparation method of the above-mentioned defluorination precipitant, comprising: using oxygen-containing organosilicon compounds and thiourea as raw materials, using ammonium sulfate as a catalyst, at 50° C. -300 ℃ reaction for 10min-72h, that is, the defluorination precipitant is obtained.

On the basis of the above technical solutions, the present invention can also be improved as follows.

Further, the molar ratio of the ammonium sulfate to the oxygen-containing organosilicon compound is 0.1:1-10:1.

The present invention solves the above technical problems and also provides the following technical scheme: the application of the above-mentioned defluorination precipitant in the defluorination of polluted acid wastewater, metallurgical waste liquid and/or metallurgical feed liquid in the metallurgical industry.

The present invention solves the above-mentioned technical problems and also provides the following technical scheme: a method for defluorination of polluted acid wastewater by using the above-mentioned defluorination precipitation agent, comprising:

Add fluorine-removing precipitant to the polluted acid wastewater, and mix and react at 0℃-100℃ for 10min-24h to generate hydrophobic fluorine-containing precipitate, that is, the fluoride ion is removed by the method of precipitation, and the hydrophobic fluorine-containing precipitate is separated from the polluted acid wastewater. , respectively recover the hydrophobic fluorine-containing precipitation and the purified sewage acid wastewater for resource utilization.

The beneficial effects of the method for defluorination of polluted acid wastewater by the defluorination precipitation agent of the present invention are:

The method for removing fluorine from the polluted acid wastewater by the fluorine-removing precipitant of the present invention enables the fluoride ions in the polluted acid wastewater to form a hydrophobic fluorine-containing precipitation, and precipitates a solution, the reaction process is not interfered by the coexisting ions in the polluted acid wastewater, and has high Ability to selectively remove fluorine. Compared with the conventional fluorine removal method, the fluorine-containing precipitate produced after defluorination is reduced by more than 96%, and the reuse of the fluorine-containing precipitate and the purified polluted acid wastewater can be realized.

On the basis of the above technical solutions, the present invention can also be improved as follows.

Further, the molar ratio of the defluorination precipitant to the fluoride ion in the polluted acid wastewater is 0.01:1-100:1.

Further, the mixed reaction mode includes mechanical stirring, magnetic stirring or rotary mixing.

Further, the separation method includes plate filtration, membrane separation, sand filtration, centrifugation or suction filtration.

Further, the hydrophobic fluorine-containing precipitation can be used as a waterproofing agent, retarder and/or adhesive for building materials; the purified foul acid wastewater is evaporated and concentrated to obtain high-concentration acid, which can be reused as acid leaching process.

Detailed ways

The principles and features of the present invention are described below, and the examples are only used to explain the present invention, but not to limit the scope of the present invention.

Example 1

A preparation method of a defluorination precipitant, comprising:

Using 0.2 mol of methyltriacetoxysilane and 0.1 mol of thiourea as raw materials, 0.02 mol of ammonium sulfate as a catalyst, after uniform mixing, react at 170° C. for 5 h to obtain a defluorination precipitant, which is sealed and stored for later use.

A method for defluorination of polluted acid wastewater by using the above-mentioned defluorination precipitation agent, comprising:

Take 500mL of polluted acid wastewater containing 50g/LH ₂ SO ₄ and 1000mg/L fluoride ions, add 1g of defluorinated precipitant, stir magnetically for 2 hours at 60°C, and separate the fluorine-containing precipitate from the polluted acid wastewater by suction filtration, The fluoride ion concentration in the treated polluted acid wastewater was measured by the ion selective electrode method to be 9 mg/L, the dry weight of the fluorine-containing precipitate was 1.4 g, and the sulfuric acid concentration was 50 g/L. The recovered fluorine-containing precipitate was alkali-dissolved and used for concrete waterproofing The purified foul acid wastewater is reused in the acid leaching process.

Example 2

A preparation method of a defluorination precipitant, comprising:

Using 0.2 mol vinyltriethoxysilane and 0.2 mol thiourea as raw materials, 0.02 mol ammonium sulfate as catalyst, after uniform mixing, react at 180° C. for 4 h to obtain a defluorination precipitant, which is sealed and stored for later use.

A method for defluorination of polluted acid wastewater by using the above-mentioned defluorination precipitation agent, comprising:

Take 1L of polluted acid wastewater containing 100g/LH ₂ SO ₄ and 2000mg/L fluoride ions, add 4g of defluorinated precipitant, and stir magnetically for 2 hours at 60°C to separate the fluorine-containing precipitate from polluted acid wastewater by sand filtration. The fluoride ion concentration in the treated polluted acid wastewater was measured by the ion selective electrode method to be 10 mg/L, the dry weight of the fluorine-containing precipitate was 5.9 g, and the sulfuric acid concentration was 100 g/L. The recovered fluorine-containing precipitate was alkali-dissolved and used as concrete waterproofing The purified foul acid wastewater is reused in the acid leaching process.

Example 3

A preparation method of a defluorination precipitant, comprising:

Using 2mol γ-aminopropyltriethoxysilane and 1mol thiourea as raw materials, and 0.5mol ammonium sulfate as catalyst, after uniform mixing, react at 180° C. for 4 hours to obtain a defluorination precipitant, which is sealed and stored for later use.

A method for defluorination of polluted acid wastewater by using the above-mentioned defluorination precipitation agent, comprising:

Take 1L of polluted acid wastewater containing 100g/LH ₂ SO ₄ and 3000mg/L fluoride ions, add 6g of defluorinated precipitant, stir magnetically for 2 hours at 60°C, and separate the fluorine-containing precipitate from polluted acid wastewater by sand filtration. The fluoride ion concentration in the treated polluted acid wastewater was measured by ion-selective electrode method to be 10 mg/L, the dry weight of the fluorine-containing precipitate was 8.9 g, and the sulfuric acid concentration was 100 g/L. Coagulant is used, and the purified foul acid wastewater is reused in the acid leaching process.

Example 4

A preparation method of a defluorination precipitant, comprising:

Using 3 mol of methoxysilane and 2 mol of thiourea as raw materials and 1 mol of ammonium sulfate as catalyst, after uniform mixing, react at 180° C. for 4 h to obtain a defluorination precipitant, which is sealed and stored for later use.

A method for defluorination of polluted acid wastewater by using the above-mentioned defluorination precipitation agent, comprising:

Take 1L of polluted acid wastewater containing 150g/LH ₂ SO ₄ and 1000mg/L fluoride ions, add 1g of defluorination precipitant, stir magnetically for 1h at 80°C, and separate the fluorine-containing precipitate from polluted acid wastewater by suction filtration, The fluoride ion concentration in the treated polluted acid wastewater was measured by the ion selective electrode method to be 10 mg/L, the dry weight of the fluorine-containing precipitate was 1.9 g, and the sulfuric acid concentration was 150 g/L. The recovered fluorine-containing precipitate was alkali-dissolved and used as concrete waterproofing The purified foul acid wastewater is reused in the acid leaching process.

Example 5

A preparation method of a defluorination precipitant, comprising:

Using 2 mol of butadienyl triethoxysilane and 2 mol of thiourea as raw materials, 0.5 mol of ammonium sulfate as catalyst, uniformly mixed, and reacted at 190° C. for 3 h to obtain a defluorination precipitant, which was sealed and stored for later use.

A method for defluorination of polluted acid wastewater by using the above-mentioned defluorination precipitation agent, comprising:

Take 1L of polluted acid wastewater containing 200g/LH ₂ SO ₄ and 3000mg/L fluoride ions, add 3g of defluorinated precipitant, stir magnetically for 2 hours at 60°C, and separate the fluorine-containing precipitate from polluted acid wastewater by sand filtration. The fluoride ion concentration in the treated polluted acid wastewater was measured by the ion selective electrode method to be 9 mg/L, the dry weight of the fluorine-containing precipitate was 5.9 g, and the sulfuric acid concentration was 200 g/L. The recovered fluorine-containing precipitate was alkali-dissolved and used for concrete waterproofing. The purified foul acid wastewater is reused in the acid leaching process.

Example 6

A preparation method of a defluorination precipitant, comprising:

Using 5 mol potassium methylsiliconate and 2 mol thiourea as raw materials, 1 mol ammonium sulfate as catalyst, after uniform mixing, react at 200° C. for 3 h to obtain a defluorination precipitant, which is sealed and stored for later use.

A method for defluorination of polluted acid wastewater by using the above-mentioned defluorination precipitation agent, comprising:

Take 5L of polluted acid wastewater containing 200g/LH ₂ SO ₄ and 2000mg/L fluoride ions, add 10g of defluorinated precipitant, stir magnetically for 30min at 80°C, separate the fluorine-containing precipitate from polluted acid wastewater by suction filtration, The fluoride ion concentration in the treated polluted acid wastewater was measured by the ion selective electrode method to be 10 mg/L, the dry weight of the fluorine-containing precipitate was 19.9 g, and the sulfuric acid concentration was 200 g/L. Coagulant is used, and the purified foul acid wastewater is reused in the acid leaching process.

Example 7

A preparation method of a defluorination precipitant, comprising:

Using 1 mol of vinyltriethoxysilane and 1 mol of thiourea as raw materials and 0.1 mol of ammonium sulfate as catalyst, after uniform mixing, react at 180° C. for 6 hours to obtain a defluorination precipitant, which is sealed and stored for later use.

A method for defluorination of polluted acid wastewater by using the above-mentioned defluorination precipitation agent, comprising:

Take 5L of polluted acid wastewater containing 100g/LH ₂ SO ₄ and 1000mg/L fluoride ions, add 5g of defluorinated precipitant, stir magnetically for 3 hours at 60°C, and separate the fluorine-containing precipitate from polluted acid wastewater by sand filtration. The fluoride ion concentration in the treated polluted acid wastewater was measured by the ion selective electrode method to be 6 mg/L, the dry weight of the fluorine-containing precipitate was 9.8 g, and the sulfuric acid concentration was 100 g/L. The recovered fluorine-containing precipitate was alkali-dissolved and used for concrete waterproofing The purified foul acid wastewater is reused in the acid leaching process.

Example 8

A preparation method of a defluorination precipitant, comprising:

Using 2 mol of methoxytrichlorosilane and 1 mol of thiourea as raw materials, 0.2 mol of ammonium sulfate as a catalyst, after uniform mixing, react at 160° C. for 9 h to obtain a defluorination precipitant, which is sealed and stored for later use.

A method for defluorination of polluted acid wastewater by using the above-mentioned defluorination precipitation agent, comprising:

Take 10L of polluted acid wastewater containing 200g/LH ₂ SO ₄ and 1000mg/L fluoride ions, add 10g of defluorinated precipitant, stir mechanically for 1 hour at 70°C, and separate the fluorine-containing precipitate from polluted acid wastewater by plate pressure filtration , the fluoride ion concentration in the treated polluted acid wastewater was determined by ion selective electrode method to be 8 mg/L, the dry weight of fluorine-containing precipitate was 19.7 g, and the sulfuric acid concentration was 200 g/L. The recovered fluorine-containing precipitate was alkali-dissolved and used as concrete. Water repellent is used, and the purified foul acid wastewater is reused in the acid leaching process.

Example 9

A preparation method of a defluorination precipitant, comprising:

Using 20mol γ-aminopropyltriethoxysilane and 10mol thiourea as raw materials, 2mol ammonium sulfate as catalyst, after uniform mixing, react at 180°C for 6h to obtain a defluorination precipitant, which is sealed and stored for later use.

A method for defluorination of polluted acid wastewater by using the above-mentioned defluorination precipitation agent, comprising:

Take 100L of polluted acid wastewater containing 100g/LH ₂ SO ₄ and 2000mg/L fluoride ions, add 200g of defluorinated precipitant, stir mechanically for 1 hour at 80°C, and separate the fluorine-containing precipitate from the polluted acid wastewater by plate filter press , the fluoride ion concentration in the treated polluted acid wastewater was measured by the ion selective electrode method to be 10mg/L, the dry weight of the fluorine-containing precipitate was 400g, and the sulfuric acid concentration was 100g/L. Coagulant is used, and the purified foul acid wastewater is reused in the acid leaching process.

Example 10

A preparation method of a defluorination precipitant, comprising:

20mol of γ-aminopropyltriethoxysilane and 5mol of thiourea are used as raw materials, and 4mol of ammonium sulfate is used as a catalyst. After uniform mixing, the reaction is carried out at 200° C. for 2 hours to obtain a defluorination precipitant, which is sealed and stored for later use.

A method for defluorination of polluted acid wastewater by using the above-mentioned defluorination precipitation agent, comprising:

Take 100L of polluted acid wastewater containing 100g/LH ₂ SO ₄ and 2000mg/L fluoride ions, add 150g of defluorinated precipitant, stir mechanically for 2 hours at 60°C, and separate the fluorine-containing precipitate from the polluted acid wastewater by plate pressure filtration , the fluoride ion concentration in the treated polluted acid wastewater was measured by the ion selective electrode method to be 10 mg/L, the dry weight of the fluorine-containing precipitate was 348 g, and the sulfuric acid concentration was 100 g/L. The recovered fluorine-containing precipitate was alkali-dissolved and used as concrete waterproofing The purified foul acid wastewater is reused in the acid leaching process.

Comparative Example 1

A method for defluorination of polluted acid wastewater by using milk of lime, comprising:

Take 1L of polluted acid wastewater containing 100g/LH ₂ SO ₄ and 3000mg/L fluoride ions, add 56g of lime emulsion, stir magnetically for 2 hours, and separate the fluorine-containing precipitate from polluted acid wastewater by suction filtration. The fluoride ion concentration in the wastewater was determined by ion selective electrode method to be 20mg/L, and the dry weight of the fluorine-containing precipitate was 155g. The pH of the treated polluted acid wastewater was close to neutral and had no reuse value.

According to the situation of Examples 1 to 10, whether the present invention is a small-scale (0.5-10L) test in a laboratory or a 100L semi-industrial test in an enlarged scale, the fluoride ion concentration in the purified polluted acid wastewater is all ≤10mg/ L. The amount of fluorine-containing precipitation produced is basically the sum of the amount of fluorine-removing precipitant and the mass of fluoride ions. The fluorine-removing precipitant has basically no residue in the purified foul acid wastewater, and the concentration of the foul acid wastewater after defluorination It remains basically unchanged and has reuse value.

In Comparative Example 1, the conventional lime neutralization method was used to carry out the defluorination test. The dosage of lime milk was as high as 56g, and the fluoride ion concentration in the treated sewage was 20mg/L. After the lime milk reacted with a large amount of sulfate radicals, 155g was produced. The fluorine-containing gypsum slag cannot realize the reuse of valuable components. Under the same conditions, the dosage of the fluorine-removing agent in Example 3 of the present invention is only 6g, and after the reaction, only 8.9g of fluorine-containing precipitation is produced, and this part of the fluorine-containing precipitation and the source of purified sewage acid wastewater can be realized. reuse.

The above-mentioned comparative experiments demonstrate that the inventiveness and defluorination principle of the fluorine-removing precipitant of the present invention overcomes the disadvantages of large amount of hazardous solid wastes and inability to recover useful resources after the treatment of existing polluted acid wastewater. The fluorine process produces almost no waste, which not only saves production costs for enterprises, but also produces excellent economic and social benefits, with great advantages and application prospects.

The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection of the present invention. within the range.

Claims (10)

1. A defluorination precipitating agent is characterized by comprising the following components in a molar ratio of 0.01: 1-100: 1 and thiourea.

2. A defluorination precipitating agent according to claim 1, wherein said oxygen containing organosilicon compound comprises any one or more of methyltriacetoxysilane, methoxytrichlorosilane, dimethoxydichlorosilane, phenyltrichlorosilane, methoxysilane, ethoxysilane, methylsilicol, butadienyltriethoxysilane, potassium methylsilicol, vinyltriethoxysilane and γ -aminopropyltriethoxysilane.

3. A method of preparing a defluorination precipitating agent as defined in any one of claims 1 or 2, comprising: taking an oxygen-containing organic silicon compound and thiourea as raw materials, taking ammonium sulfate as a catalyst, and reacting at 50-300 ℃ for 10min-72h to obtain the defluorination precipitator.

4. The production method according to claim 3, characterized in that the molar ratio of the ammonium sulfate to the oxygen-containing organosilicon compound is 0.1: 1-10: 1.

5. use of the defluorination precipitating agent according to any one of the claims 1 or 2 in defluorination of waste acid water, waste metallurgical liquid and/or metallurgical liquid in the metallurgical industry.

6. A method for removing fluorine from waste acid wastewater by using the fluorine removal precipitator in any one of claims 1 or 2, comprising:

adding a defluorination precipitator into the waste acid water, mixing and reacting for 10min-24h at 0-100 ℃, generating hydrophobic fluorine-containing precipitate, separating the hydrophobic fluorine-containing precipitate from the waste acid water, and respectively recovering the hydrophobic fluorine-containing precipitate and the purified waste acid water for resource utilization.

7. The method according to claim 6, wherein the molar ratio of the defluorination precipitating agent to the fluoride ions in the waste acid water is 0.01: 1-100: 1.

8. the method of claim 6, wherein the mixing reaction means comprises mechanical stirring, magnetic stirring, or rotational mixing.

9. The method of claim 6, wherein the separation means comprises plate press filtration, membrane separation, sand filtration, centrifugation, or suction filtration.

10. The method of claim 6, wherein the hydrophobic fluorine-containing precipitate is capable of acting as a water repellent, retarder and/or adhesive for building materials; and evaporating and concentrating the purified waste acid and waste water to prepare high-concentration acid which can be reused in an acid leaching process.