CN110980739A - Method for recycling high-purity product from pickling waste liquid step by step - Google Patents
Method for recycling high-purity product from pickling waste liquid step by step Download PDFInfo
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- CN110980739A CN110980739A CN201911077767.3A CN201911077767A CN110980739A CN 110980739 A CN110980739 A CN 110980739A CN 201911077767 A CN201911077767 A CN 201911077767A CN 110980739 A CN110980739 A CN 110980739A
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B33/00—Silicon; Compounds thereof
- C01B33/08—Compounds containing halogen
- C01B33/10—Compounds containing silicon, fluorine, and other elements
- C01B33/103—Fluosilicic acid; Salts thereof
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B17/00—Sulfur; Compounds thereof
- C01B17/96—Methods for the preparation of sulfates in general
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B21/00—Nitrogen; Compounds thereof
- C01B21/20—Nitrogen oxides; Oxyacids of nitrogen; Salts thereof
- C01B21/48—Methods for the preparation of nitrates in general
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
- C01D9/00—Nitrates of sodium, potassium or alkali metals in general
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
- C01F11/00—Compounds of calcium, strontium, or barium
- C01F11/46—Sulfates
- C01F11/462—Sulfates of Sr or Ba
Abstract
The invention discloses a method for recycling high-purity products from pickling waste liquid step by step, which comprises the following steps: step one, recovering fluorosilicate; firstly, adding silicon or silicon dioxide into the waste pickle liquor to convert HF in the waste liquor into H2SiF6Then to H after completion of the conversion2SiF6Adding a first precipitator for neutralization salt-forming reaction to generate fluorosilicate precipitate, generating a first mother solution, cleaning the obtained fluorosilicate precipitate, drying and pulverizing to obtain a first target product fluorosilicate; step two, adding a second precipitator into the first mother liquor to generate sulfur through a displacement reactionPrecipitating acid salt to generate a second mother solution, cleaning the obtained sulfate precipitate, drying and pulverizing to obtain a second target sulfate; and step three, evaporating and concentrating the second mother liquor, cooling and crystallizing to generate crystalline nitrate, drying and pulverizing to obtain a third target product nitrate, generating a third mother liquor, refluxing 80% of the third mother liquor, mixing with the second mother liquor, and treating 20% of the third mother liquor according to dangerous solid wastes. The method sequentially recovers the high-purity fluosilicate and the nitrate step by step, the recovered products can reach the relevant standards of GB/T36936-2018, GB/T4553-.
Description
Technical Field
The invention relates to the technical field of waste acid resource recycling, in particular to a method for recycling high-purity products from pickling waste liquid step by step.
Background
The technical scheme is given in 'a process for recycling waste acid' with application number 2018101391405: a precipitator is added into the first reactor to separate lead sulfate filter residue, the process aims to remove sulfate radical in waste acid, and the used precipitator is soluble lead salt such as lead nitrate. However, the above process has the following drawbacks:
1, Pb2+With SO4 2-Combined with the formation of PbSO4Is a slightly water-soluble electrolyte with a solubility of 0.28%. The use of soluble lead salts for the separation of sulfate ions has limited effectiveness in the separation and recovery of sulfate and also introduces lead ions into the spent acid solution. On one hand, lead ions are pigments which have high toxicity and are strictly controlled in the aspects of chemical industry and environmental pollution, and lead intake by a human body can cause blood lead diseases; on the other hand, after the lead sulfate solution is generated in the waste acid, more sulfate radicals and lead ions are generated in the waste acid, the sulfate radicals and the lead ions are strict control indexes influencing the specification of a sodium fluosilicate product, and the recycled sodium fluosilicate is difficult to reach GB/T36936-2018.
Secondly, the products of fluosilicate and nitrate recovered by the patent application are not detected, and whether the products reach the national standard or not is unknown. According to national regulations, the purity of the product recovered from the dangerous solid waste must reach national standard or industrial standard, and if the purity of the product does not reach the standard, the product has use value and must be disposed according to the dangerous solid waste.
Disclosure of Invention
The invention aims to provide a method for recycling high-purity products from pickling waste liquid step by step, the method sequentially recycles high-purity fluosilicate and nitrate step by step, the recycled products can reach relevant standards such as GB/T36936-2018 and the like, the cost is low, the recycling effect of the pickling waste liquid is good, and the method has little pollution to the environment.
In order to solve the technical problem, the technical scheme of the invention is as follows:
a method for recycling high-purity products from pickling waste liquid step by step comprises the following steps:
step one, recovering fluorosilicate;
firstly, adding silicon or silicon dioxide into the waste pickle liquor to convert HF in the waste liquor into H2SiF6；
Then to completion H2SiF6Adding a first precipitator into the converted waste liquid to generate fluorosilicate precipitate, and filtering the precipitate to obtain a first mother liquid;
cleaning and drying the obtained fluosilicate precipitate to prepare powder to obtain target fluosilicate;
step two, recovering sulfate;
adding a second precipitator into the first mother liquor to generate sulfate precipitate through a displacement reaction;
filtering the sulfate precipitate to obtain a second mother liquor;
cleaning the obtained sulfate precipitate, drying and pulverizing to obtain target sulfate;
step three, recovering nitrate;
evaporating the second mother liquor;
cooling and crystallizing;
drying and pulverizing to obtain the target nitrate.
In the present invention, silicon or silicon dioxide is converted into H with HF2SiF6The reaction equation of (a) is as follows:
Si+6HF——H2SiF6+2H2↑
SiO2+6HF——H2SiF6+2H2O
preferably, the first precipitator comprises one or more of sodium sulfate, sodium chloride, potassium sulfate, potassium chloride, sodium hydroxide or potassium hydroxide.
In the present invention, M is used as the first precipitant2SO4Or MCl or MOH, wherein M is K or Na,first precipitating agent and H2SiF6The reaction equation of (a) is as follows:
H2SiF6+M2SO4——M2SiF6↓+H2SO4；
H2SiF6+2MCl——M2SiF6↓+2HCl；
H2SiF6+2MOH——M2SiF6↓+2H2O；
as can be seen from the reaction formula, no dangerous impurities are introduced into the waste acid by using the first precipitator, so that the stable impurity type in the first mother liquor is ensured while the fluorosilicate product is obtained, and the subsequent treatment is facilitated.
Preferably, the fluosilicate precipitate is Na2SiF6Or K2SiF6. The fluosilicate recovered by the invention meets GB/T23936-2018.
Preferably, the water for cleaning the fluorosilicate precipitate in the first step is introduced to be converted into H2SiF6In the waste liquid of (2). Returning the water for cleaning the fluosilicate to be converted into H2SiF6In the waste liquid, the newly generated waste water is directly introduced into the process flow of waste acid recovery in the process of recovering the fluosilicate, so that the concentration of the acid liquor is favorably reduced, and the waste water generated in the step directly flows into the waste liquid to be directly recovered.
Preferably, the second precipitator in the second step is barium nitrate or barium chloride. The soluble barium salt is used for precipitating sulfate radical, so that salts which are toxic to the environment or human are avoided, the purity of the obtained barium sulfate can be ensured, and the recovered barium sulfate can be further used as a product.
Preferably, the sulfate salt in the second step is precipitated as barium sulfate. Compared with lead sulfate, the barium sulfate precipitate has lower solubility in water and acid solution, is more stable, and is more beneficial to the recovery and separation of sulfate radicals.
Preferably, the water for cleaning the sulfate precipitate in the second step is introduced into the solution in which the displacement reaction occurs. The method leads the water for cleaning the sulfate precipitate into the solution which has the replacement reaction, namely, the water used in the recovery process is purified to a certain degree while the sulfate and the nitrate are recovered, and the workload of the subsequent sewage treatment is reduced.
Preferably, the cooling crystallization temperature of the third step is 0 to 20 ℃. The invention realizes the separation and purification of acid salt by utilizing the obvious reduction of the solubility of nitrate along with the reduction of temperature and the basically unchanged solubility of chloride salt in water along with the temperature, and the purity of the purified nitrate meets the GB/T4553-2016-to-standard by controlling the temperature of cooling crystallization.
Preferably, the nitrate recovered in the third step is sodium nitrate or potassium nitrate.
Preferably, the solution after cooling and crystallization in the third step is refluxed and evaporated or is subjected to sewage treatment.
By adopting the technical scheme, the invention has the beneficial effects that:
firstly, the invention uses silicon or silicon dioxide to convert HF in waste acid into H2SiF6To transformation with H2SiF6The first precipitator is added into the waste liquid to generate fluorosilicate precipitate, and the generated fluorosilicate product has high purity, meets the standard of national first-class products, can be used as a product and does not generate other hazardous wastes;
secondly, evaporating and crystallizing the second mother liquor separated in the second step to obtain high-purity nitrate with use value, and the recovery effect is good; in the third step, nitrate is further purified through evaporation and crystallization, and compared with the prior art, the ion species in the second mother liquor are reduced after the first step and the second step, so that on one hand, the recovered nitrate is prevented from containing a large amount of impurities, on the other hand, the influence of nitrate radicals on the purification of fluosilicate is avoided, and the high-purity fluosilicate and nitrate are favorably obtained;
thirdly, the first step and the second step are combined, so that the fluosilicate and the sulfate can be classified, separated and recovered, compared with the prior art, the recovered fluosilicate contains less sulfate radicals and lead ions and meets the relevant national standard, and the recovered fluosilicate can be used as a product; meanwhile, sulfate precipitate with high purity and use value is obtained in the process of classification and recovery, and the recovery effect is good;
step four, the target product is separated in a mode of precipitating the target product in the first step and the second step, so that the separation is simple and convenient, the production is facilitated, the separation effect is good, and the cost is low; the three-way supercooling crystallization is combined to separate and purify the nitrate from the chloride by utilizing different characteristics of the solubility of the nitrate and the chloride along with the temperature change in the solution, the nitrate with the purity meeting the national standard is prepared by recovery, and the recovery effect is good;
the invention purifies the pickling waste liquid to a certain degree, realizes the recovery of substances with purity meeting the relevant national standards in the purification process, reduces the concentration of toxic ions in the treated pickling waste liquid, recovers to obtain high-purity products, purifies the pickling waste liquid, changes waste into valuables to a certain degree, and recycles the recovered substances.
Thereby achieving the above object of the present invention.
Detailed Description
In order to further explain the technical solution of the present invention, the present invention is explained in detail by the following specific examples.
Example 1
The composition and the content of the waste pickle liquor used in this example are shown in table 1.
Table 1 composition and content of pickling waste liquid in example 1
| Name of the component | Mass fraction of each substance (%) |
| H2SiF6 | 10.8 |
| HF | 5.2 |
| HNO3 | 6.9 |
| H2SO4 | 0.8 |
| Na | 0.8 |
| H2O | 75.5 |
The method for recycling the high-purity product from the pickling waste liquid step by step comprises the following steps:
step one, recovering fluorosilicate;
firstly, adding silicon into the waste pickle liquor to convert HF in the waste pickle liquor into H2SiF6；
Followed by conversion to H2SiF6Adding a first precipitator into the waste liquid, wherein the first precipitator is sodium sulfate.
Generating sodium fluosilicate, and filtering the precipitate to obtain a first mother liquor;
cleaning and drying the obtained fluosilicate precipitate to prepare powder to obtain target fluosilicate;
introducing water for cleaning the fluosilicate precipitate in the first step until H is converted2SiF6In the waste liquid of (2).
Step two, recovering sulfate;
adding a second precipitator into the first mother liquor to generate sulfate precipitate through a displacement reaction; and in the second step, the second precipitator is barium nitrate. And precipitating the sulfate in the second step into barium sulfate.
Filtering the barium sulfate to obtain a second mother liquor;
cleaning the obtained barium sulfate precipitate, drying and pulverizing to obtain target sulfate;
and step two, introducing water for cleaning barium sulfate into the solution in which the replacement reaction occurs.
Step three, recovering nitrate;
evaporating the second mother liquor;
the process conditions for evaporating the second mother liquor are as follows: water bath at 80-90 deg.c
Cooling and crystallizing; and the cooling crystallization temperature of the third step is 0-20 ℃.
Drying and pulverizing;
and obtaining the target sodium nitrate recovered in the third step.
The solution after cooling crystallization in the third step is 5-6% of the volume of the stock solution, the solubility of the evaporated sodium nitrate is 170% at 80 ℃, the solubility is 75% at 10 ℃, the recovery rate of the single-time concentration crystallization sodium nitrate is more than 50%, 80% of the solution after cooling crystallization is returned and reused to be mixed with the second mother solution, and the solution after 20% cooling crystallization is treated according to dangerous solid waste.
The amounts of the substances and the requirements for the substances in the first to third steps of this example are shown in table 2, and the yields, the purities, and the corresponding impurities of the obtained target products, sodium fluorosilicate, barium sulfate, and sodium nitrate, are shown in table 3. The composition of the solution after cooling crystallization in step three is shown in Table 4.
Table 2 example 1 process conditions, materials and amounts used from step one to step three
Table 3 example 1 recovery of the target product purity
TABLE 4 composition of the solution after cooling crystallization in step three in example 1
| The main components | Mass fraction |
| Sodium sulfate | 0.85％ |
| Sodium nitrate | 77％ |
Example 2
The main differences between this embodiment and embodiment 1 are:
the HF conversion product used in the step one is SiO2The first precipitator is sodium chloride; in the second step, the second precipitating agent is barium chloride, and the specific dosage is shown in table 5.
The yields, purities and corresponding impurity conditions of the target products sodium fluorosilicate, barium sulfate and sodium nitrate recovered in this example are shown in table 6. The composition of the solution after cooling crystallization in step three is shown in Table 7.
TABLE 5 example 2 Process conditions, materials and amounts used from step one to step three
Table 6 example 2 recovery of the target product purity
TABLE 7 composition of the solution after cooling crystallization in step three in example 2
| The main components | Mass fraction |
| Sodium sulfate | 1.13％ |
| Sodium nitrate | 76.2％ |
Example 3
The main differences between this embodiment and embodiment 1 are:
the HF conversion product used in the step one is SiO2The first precipitator is sodium hydroxide; in the second step, the second precipitator is barium chloride, and the specific dosage is shown in table 8.
The yields, purities and corresponding impurity conditions of the target products sodium fluorosilicate, barium sulfate and sodium nitrate recovered in this example are shown in table 9. The composition of the solution after cooling crystallization in step three is shown in Table 10.
TABLE 8 example 3 Process conditions, materials and amounts used in step one to step three
Table 9 example 3 recovery of the target product purity
TABLE 10 composition of the solution after cooling crystallization in example 3 through step three
| The main components | Mass fraction |
| Sodium sulfate | 1.5％ |
| Sodium nitrate | 75％ |
Example 4
The main differences between this embodiment and embodiment 1 are:
the composition of the pickle liquor of this example is detailed in Table 11.
Table 11 example 4 composition of pickle liquor material
| Name of the component | Potassium-containing waste acid mass fraction (%) |
| H2SiF6 | 12.2 |
| HF | 6.3 |
| HNO3 | 5.9 |
| H2SO4 | 0.4 |
| K | 0.9 |
| H2O | 74.3 |
In the first step, potassium chloride is used as a first precipitator; in the second step, the second precipitator is barium chloride, and the specific dosage is shown in table 12.
In the third step, the target of recovery is potassium nitrate.
The yield, purity and corresponding impurity condition of the target products potassium fluosilicate, barium sulfate and potassium nitrate recovered in this example are shown in table 13. The composition of the solution after cooling crystallization in step three is shown in Table 14. After evaporation in the third step, the volume of the solution is 5-6% of that of the stock solution, the potassium nitrate after evaporation has 180% solubility at 70 ℃, 15% solubility at 10 ℃, and the recovery rate of the single-concentration crystallized potassium nitrate is more than 90%; the solution is recovered and reused after evaporation without discharging.
TABLE 12 example 4 Process conditions, materials and amounts used from step one to step three
Table 13 example 4 recovery of the target product purity
TABLE 14 composition of the solution after cooling crystallization in example 4 through step three
| The main components | Mass fraction |
| Potassium sulfate | 1.5％ |
| Potassium nitrate | 15％ |
The pickling waste liquid refers to waste acid generated by hydrofluoric acid, nitric acid, wool making and pickling of monocrystalline silicon and polycrystalline silicon wafers in the photovoltaic industry; alkali washing the waste alkali by sodium hydroxide or potassium hydroxide; the pickling waste liquid is the single waste acid or the mixed liquid of the waste acid and the waste alkali, for example, the mixed liquid generated by sodium hydroxide alkali washing is sodium-containing waste acid and is used for recovering sodium salt; the mixed solution generated by potassium hydroxide alkali washing is potassium-containing waste acid which is used for recovering potassium salt. The method is simultaneously suitable for pickling electronic elements, circuit boards and silicate materials and recovering the etching waste acid, and the concentration ranges of all substances in the recyclable waste acid solution are shown in the table 15.
TABLE 15 recoverable Pickling waste liquor composition concentration Range
| Name of the component | Potassium-containing waste acid concentration (%) | Sodium-containing waste acid concentration (%) |
| H2SiF6 | 5-20 | 5-20 |
| HF | 1-10 | 1-10 |
| HNO3 | 2-8 | 2-8 |
| H2SO4 | ＜2 | ＜2 |
| K | ＜1 | / |
| Na | / | ＜0.8 |
| H2O | 70-85 | 70-85 |
Claims (10)
1. A method for recycling high-purity products from pickling waste liquid step by step is characterized by comprising the following steps: the method comprises the following steps:
step one, recovering fluorosilicate;
firstly, adding silicon or silicon dioxide into the waste pickle liquor to convert HF in the waste liquor into H2SiF6;
Then to completion H2SiF6Adding a first precipitator into the converted waste liquid to generate fluorosilicate precipitate, and filtering the precipitate to obtain a first mother liquid;
cleaning and drying the obtained fluosilicate precipitate to prepare powder to obtain target fluosilicate;
step two, recovering sulfate;
adding a second precipitator into the first mother liquor to generate sulfate precipitate through a displacement reaction;
filtering the sulfate precipitate to obtain a second mother liquor;
cleaning the obtained sulfate precipitate, drying and pulverizing to obtain target sulfate;
step three, recovering nitrate;
evaporating the second mother liquor;
cooling and crystallizing;
drying and pulverizing to obtain the target nitrate.
2. The method for stepwise recovering a high-purity product from a spent pickling solution according to claim 1, comprising the steps of: the first precipitator comprises one or more of sodium sulfate, sodium chloride, potassium sulfate, potassium chloride, sodium hydroxide or potassium hydroxide.
3. The method for stepwise recovering a high-purity product from a spent pickling solution according to claim 1, comprising the steps of: the fluosilicate precipitate is Na2SiF6Or K2SiF6。
4. The method for stepwise recovering a high-purity product from a spent pickling solution according to claim 1, comprising the steps of: introducing water for cleaning the fluosilicate precipitate in the first step until H is converted2SiF6In the waste liquid of (2).
5. The method for stepwise recovering a high-purity product from a spent pickling solution according to claim 1, comprising the steps of: and in the second step, the second precipitator is barium nitrate or barium chloride.
6. The method for stepwise recovering a high-purity product from a spent pickling solution according to claim 1, comprising the steps of: and precipitating the sulfate in the second step into barium sulfate.
7. The method for stepwise recovering a high-purity product from a spent pickling solution according to claim 1, comprising the steps of: and (5) introducing water for cleaning the sulfate precipitate in the step two into the solution for carrying out the replacement reaction.
8. The method for stepwise recovering a high-purity product from a spent pickling solution according to claim 1, comprising the steps of: and the cooling crystallization temperature of the third step is 0-20 ℃.
9. The method for stepwise recovering a high-purity product from a spent pickling solution according to claim 1, comprising the steps of: and the nitrate recovered in the third step is sodium nitrate or potassium nitrate.
10. The method for stepwise recovering a high-purity product from a spent pickling solution according to claim 1, comprising the steps of: and in the third step, the solution after cooling and crystallization is refluxed and evaporated or is subjected to sewage treatment.
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111729494A (en) * | 2020-06-08 | 2020-10-02 | 江西渠成氟化学有限公司 | Hydrogen fluoride tail gas treatment method |
| CN112794333A (en) * | 2021-01-13 | 2021-05-14 | 赣州帝晶光电科技有限公司 | Preparation method of fluosilicic acid byproduct of fluorine-containing waste liquid |
| CN114853074A (en) * | 2022-04-22 | 2022-08-05 | 河南省氟基新材料科技有限公司 | NaFeF production by using semiconductor waste acid 3 Method (2) |
| CN115838183A (en) * | 2023-02-15 | 2023-03-24 | 中南大学 | Method for separating silicon and magnesium from black talc |
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|---|---|---|---|---|
| JPS577812A (en) * | 1980-06-13 | 1982-01-16 | Nippon Mining Co Ltd | Removing method for fluorine from waste sulfuric acid |
| CN106830480A (en) * | 2017-01-22 | 2017-06-13 | 冯合生 | Etch the processing system and method for high-concentration waste liquid recycling |
| CN108190945A (en) * | 2018-02-11 | 2018-06-22 | 应韵进 | A kind of resource utilization process of spent acid |
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2019
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
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| JPS577812A (en) * | 1980-06-13 | 1982-01-16 | Nippon Mining Co Ltd | Removing method for fluorine from waste sulfuric acid |
| CN106830480A (en) * | 2017-01-22 | 2017-06-13 | 冯合生 | Etch the processing system and method for high-concentration waste liquid recycling |
| CN108190945A (en) * | 2018-02-11 | 2018-06-22 | 应韵进 | A kind of resource utilization process of spent acid |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111729494A (en) * | 2020-06-08 | 2020-10-02 | 江西渠成氟化学有限公司 | Hydrogen fluoride tail gas treatment method |
| CN112794333A (en) * | 2021-01-13 | 2021-05-14 | 赣州帝晶光电科技有限公司 | Preparation method of fluosilicic acid byproduct of fluorine-containing waste liquid |
| CN114853074A (en) * | 2022-04-22 | 2022-08-05 | 河南省氟基新材料科技有限公司 | NaFeF production by using semiconductor waste acid 3 Method (2) |
| CN115838183A (en) * | 2023-02-15 | 2023-03-24 | 中南大学 | Method for separating silicon and magnesium from black talc |
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