CN110980743A - Method for preparing sodium fluoride and white carbon black by using caprolactam waste alkali - Google Patents
Method for preparing sodium fluoride and white carbon black by using caprolactam waste alkali Download PDFInfo
- Publication number
- CN110980743A CN110980743A CN201911370009.0A CN201911370009A CN110980743A CN 110980743 A CN110980743 A CN 110980743A CN 201911370009 A CN201911370009 A CN 201911370009A CN 110980743 A CN110980743 A CN 110980743A
- Authority
- CN
- China
- Prior art keywords
- sodium
- filtrate
- carbon black
- white carbon
- crystals
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Images
Classifications
-
- 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
- C01B33/113—Silicon oxides; Hydrates thereof
- C01B33/12—Silica; Hydrates thereof, e.g. lepidoic silicic acid
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
- C01D3/00—Halides of sodium, potassium or alkali metals in general
- C01D3/02—Fluorides
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/80—Compositional purity
Abstract
The invention discloses a method for preparing sodium fluoride and white carbon black by using caprolactam waste alkali, which comprises the following steps: 1) mixing the waste alkali and desalted water, heating for dissolving, filtering while the mixture is hot, removing insoluble impurities to obtain a filtrate A, and cooling and crystallizing the filtrate A to obtain crystals of sodium carbonate decahydrate and a filtrate B; 2) adding fluosilicic acid into the filtrate B, growing crystals after reaction, and filtering to obtain sodium fluosilicate crystals and filtrate C; 3) mixing the sodium fluosilicate obtained in the step 2) with the sodium carbonate decahydrate obtained in the step 1), adding water, stirring, reacting, and finally adding a surfactant and uniformly mixing; 4) and 3) standing the feed liquid obtained in the step 3) for settling, then pumping out supernatant liquid to separate sodium fluoride and white carbon black, and centrifugally drying to obtain sodium fluoride crystals and white carbon black. The invention comprehensively utilizes the caprolactam waste alkali and the by-product fluosilicic acid in the phosphate fertilizer industry, changes waste into valuable and has higher environmental protection and economic value.
Description
Technical Field
The invention relates to the recycling of caprolactam waste alkali and fluosilicic acid, in particular to a method for preparing sodium fluoride and white carbon black by utilizing caprolactam waste alkali and fluosilicic acid as a byproduct of phosphorus chemical industry.
Background
At present, a large amount of incineration waste alkali is generated in the caprolactam production process in China, the waste alkali contains a large amount of sodium sulfate impurities, the product phase is poor, the purity is low, and the separation is quite difficult, so that an enterprise generally takes the waste alkali as a burden to sell the waste alkali at an extremely low price, and the economic value is extremely low. On the other hand, a large amount of by-product fluosilicic acid in the phosphate fertilizer industry in China is mostly recovered in the form of sodium fluosilicate, but the sodium fluosilicate has narrow application, low selling price and low economic benefit, thereby seriously restricting the enthusiasm of enterprises for recovering the fluosilicic acid and the development of the phosphate fertilizer industry and also causing the waste of fluorine resources in China.
CN104030317A discloses a process for preparing sodium fluorosilicate from sodium carbonate and fluorosilicic acid, and then further preparing sodium fluoride and white carbon black, wherein sodium carbonate decahydrate is directly used as a raw material for production, which is relatively high in cost, and the obtained sodium fluoride and white carbon black are easy to form coprecipitation and have poor separation effect.
Disclosure of Invention
The invention provides a method for preparing sodium fluoride and white carbon black by using caprolactam waste alkali, which can effectively utilize the caprolactam waste alkali and a byproduct fluosilicic acid in the phosphate fertilizer industry to finally prepare the sodium fluoride and the white carbon black, thereby changing waste into valuable and improving the added value of products.
The technical scheme of the invention is that the method for preparing sodium fluoride and white carbon black by using caprolactam waste alkali comprises the following steps:
1) mixing the waste alkali and desalted water, heating for dissolving, filtering while the mixture is hot, removing insoluble impurities to obtain a filtrate A, and cooling and crystallizing the filtrate A to obtain crystals of sodium carbonate decahydrate and a filtrate B;
2) adding fluosilicic acid into the filtrate B, growing crystals after reaction, and filtering to obtain sodium fluosilicate crystals and filtrate C;
3) mixing the sodium fluosilicate obtained in the step 2) with the sodium carbonate decahydrate obtained in the step 1), adding water, stirring, reacting, and finally adding a surfactant and uniformly mixing;
4) and 3) standing the feed liquid obtained in the step 3) for settling, then pumping out supernatant liquid to separate sodium fluoride and white carbon black, and centrifugally drying to obtain sodium fluoride crystals and white carbon black.
Further, the waste alkali in the step 1) comprises, by mass, 60-90% of sodium carbonate, 10-40% of sodium sulfate and 0-2% of insoluble impurities.
Further, in the step 1), the waste alkali and the desalted water are mixed according to the weight ratio of 1: 1-2, and the mixture is heated to 35-80 ℃. The content of sodium carbonate in caprolactam waste alkali is 60-90 wt%, and the content of sodium sulfate is 8-40 wt%.
Further, the temperature for dissolving and filtering in the step 1) is controlled to be 40-60 ℃, and the solubility of sodium carbonate and sodium sulfate is maximum at the moment.
Further, the temperature is 5-30 ℃ when cooling and crystallizing in the step 1).
Further, the temperature is 10-20 ℃ when cooling and crystallizing in the step 1). Because the content of sodium carbonate in the waste alkali is higher, the sodium carbonate is firstly supersaturated and separated out, and the sodium sulfate is still dissolved in the medium solution.
Further, the mass fraction of the fluosilicic acid added in the step 2) is 7-15%. And reacting sodium carbonate and sodium sulfate in the filtrate B with fluosilicic acid to generate sodium fluosilicate and corresponding acid.
Further, in the step 3), mixing sodium fluosilicate and sodium carbonate decahydrate according to the proportion of 1: 1.2-1.5, and adding water to prepare a solution with the mass fraction of 20-30%; the reaction temperature is 85-95 ℃, and when the reaction is finished, a surfactant with the mass fraction of 0.2-0.5% is added, and the stirring is continued to ensure that the surfactant is uniformly dispersed.
Further, the surfactant is span20, Tween 60 or PEG-800. Through the dual effects of the surfactant and the gravity, the sodium fluoride is precipitated, the white carbon black is suspended in the middle layer, the supernatant is extracted, the sodium fluoride is obtained by filtration, and the white carbon black is obtained by centrifuging the filtrate. Compared with the method of directly adopting specific gravity difference flotation solid-solid separation after the treatment by adopting the surfactant, the method has better separation effect and better purity of the prepared product.
Further, the standing in the step 3) is carried out for 15-30 min for sedimentation. And pumping out the supernatant to separate sodium fluoride and white carbon black, filtering under reduced pressure to obtain sodium fluoride crystals, and performing centrifugal separation to obtain white carbon black at the rotating speed of 2000-4000 revolutions per minute.
Further, the sodium fluoride crystal and the white carbon black are respectively dried, and the drying temperature is 80-110 ℃. Preferably 85 to 95 ℃.
The reaction equation involved in the invention is as follows:
H2SiF6+ Na2CO3→Na2SiF6+ H2O + CO2↑
H2SiF6+ Na2SO4→Na2SiF6+ H2SO4
Na2SiF6+ 2Na2CO3→6NaF + SiO2+ 2CO2↑
the invention has the following beneficial effects:
1. because the caprolactam waste alkali contains sodium carbonate and sodium sulfate, if the caprolactam waste alkali is directly added with water and then reacts with fluosilicic acid, the sulfuric acid generated after the reaction of the sodium sulfate and the fluosilicic acid interferes the reaction, and the sulfuric acid and the fluosilicic acid have the condition of competing for the reaction of the sodium carbonate, so that the sodium fluoride and the white carbon black with high purity cannot be obtained. The invention utilizes the characteristics of content difference and similar solubility of sodium carbonate and sodium sulfate in the waste alkali to realize the separation of sodium carbonate in the waste alkali by adopting a simple dissolving and crystallizing method, firstly obtains sodium carbonate decahydrate with high purity, and then reacts the mother liquor obtained by separation after crystallization with fluosilicic acid. The concentration of sodium sulfate in the mother liquor after sodium carbonate separation is high, sodium carbonate only accounts for a small proportion, sodium carbonate and sodium sulfate can react with fluosilicic acid to generate sodium fluosilicate crystals, then the sodium fluosilicate crystals and filtrate are obtained through filtration and separation again, the filtrate is mainly sulfuric acid and can be recycled in an acid making workshop after being collected, and the sodium fluosilicate crystals are used for reacting with sodium carbonate decahydrate to prepare sodium fluoride and white carbon black. The invention can fully utilize sodium carbonate and sodium sulfate in the waste alkali without generating waste water.
2. According to the invention, the reaction liquid is treated by adopting the surfactant, so that the better separation of sodium fluoride and white carbon black is realized. The used surfactant is nonionic surfactant, which is not ionized in water solution, has high stability, is not easily affected by strong electrolyte inorganic salt and pH, has moderate adsorption effect with the solid surface of the white carbon black, and is easy to wash and remove after separation.
3. The invention comprehensively utilizes the waste alkali of caprolactam and the by-product fluosilicic acid in the phosphate fertilizer industry, changes waste into valuable, has higher environmental protection and economic value, and in addition, intermediate products produced in the method, such as sodium carbonate and sodium fluosilicate, can be further processed according to market demands and then sold as products, so the method also has the outstanding advantages of simple process, low cost and diversified product structures.
Drawings
FIG. 1 is a process flow diagram of the method of the present disclosure.
Detailed Description
The invention will be further elucidated with reference to the following examples.
Example 1:
as shown in figure 1, 100g of waste alkali (wherein the sodium carbonate is 80wt% and the sodium sulfate is 18 wt%) is weighed, 120g of desalted water is added and mixed, then the mixture is heated to 60 ℃, and stirred and dissolved to form waste alkali liquor. Keeping the temperature at 60 ℃, filtering while the solution is hot, and removing insoluble impurities to obtain filtrate A. Cooling the filtrate A to 20 ℃, cooling and crystallizing for 2h, and filtering the fine slurry formed by cooling and crystallizing under reduced pressure to obtain 45g of crystals of sodium carbonate decahydrate and filtrate B.
Adding 20g of fluosilicic acid into the filtrate B under the condition of stirring, and reacting sodium carbonate and sodium sulfate in the filtrate B with the fluosilicic acid to generate sodium fluosilicate and corresponding acid. After the reaction is finished, growing crystals, washing and separating out 26g of sodium fluosilicate crystals and filtrate C, and recycling the filtrate C.
Mixing the sodium fluosilicate crystal obtained in the step with sodium carbonate decahydrate in a ratio of 1:1.4, adding a proper amount of water to prepare a solution with the mass fraction of 22%, stirring, heating to 91 ℃, reacting for 2 hours, adding a surfactant span20 with the mass fraction of 0.2%, and continuing stirring for 15min to uniformly disperse the surfactant.
And standing the obtained product, settling for 20min, pumping out supernatant to separate sodium fluoride and white carbon black, filtering under reduced pressure to obtain sodium fluoride crystals, carrying out centrifugal separation to obtain white carbon black at the rotating speed of 3000 r/min, and respectively drying the obtained sodium fluoride crystals and the obtained white carbon black in an oven at the temperature of 85 ℃ to obtain the sodium fluoride with the purity of 98.2% and the white carbon black with the purity of 96.5%.
Comparative example 1:
100g of waste alkali (wherein the sodium carbonate accounts for 80wt% and the sodium sulfate accounts for 18 wt%) is weighed, 120g of desalted water is added to be mixed, the mixture is heated to 60 ℃, and the waste alkali is dissolved by stirring to form waste alkali liquor. Keeping the temperature at 60 ℃, filtering while the solution is hot, and removing insoluble impurities to obtain filtrate A. And cooling the filtrate A to 20 ℃, cooling and crystallizing for 2h, and filtering fine slurry formed by cooling and crystallizing under reduced pressure to obtain 44g of crystals of sodium carbonate decahydrate and filtrate B.
Adding 20g of fluosilicic acid into the filtrate B under the condition of stirring, and reacting sodium carbonate and sodium sulfate in the filtrate B with the fluosilicic acid to generate sodium fluosilicate and corresponding acid. After the reaction is finished, growing crystals, washing and separating 25.5g of sodium fluosilicate crystals and filtrate C, and recycling the filtrate C.
Mixing the sodium fluosilicate crystal obtained in the step with sodium carbonate decahydrate in a ratio of 1:1.4, adding a proper amount of water to prepare a solution with the mass fraction of 22%, stirring, heating to 91 ℃, reacting for 2h, and continuing stirring for 15 min.
And standing the obtained product, settling for 20min, pumping out supernatant to separate sodium fluoride and white carbon black, filtering under reduced pressure to obtain sodium fluoride crystals, carrying out centrifugal separation to obtain white carbon black at the rotating speed of 3000 r/min, and respectively drying the obtained sodium fluoride crystals and the obtained white carbon black in an oven at the temperature of 85 ℃ to obtain the sodium fluoride with the purity of 78.3% and the white carbon black with the purity of 82.6%.
Example 2:
weighing 100g of waste alkali (wherein the content of sodium carbonate is 75 percent, and the content of sodium sulfate is 24 percent), adding 180g of desalted water, mixing, heating to 45 ℃, and stirring to dissolve the waste alkali to obtain waste alkali liquor. Keeping the temperature at 45 ℃, filtering while the solution is hot, and removing insoluble impurities to obtain filtrate A. And cooling the filtrate A to 15 ℃, cooling and crystallizing for 2h, and filtering fine slurry formed by cooling and crystallizing under reduced pressure to obtain 27g of crystals of sodium carbonate decahydrate and filtrate B.
Adding 25g of fluosilicic acid into the filtrate B under the condition of stirring, and reacting sodium carbonate and sodium sulfate in the filtrate B with the fluosilicic acid to generate sodium fluosilicate and corresponding acid. After the reaction is finished, growing crystals, washing and separating 30g of sodium fluosilicate crystals and filtrate C, and recycling the filtrate C.
Mixing the sodium fluosilicate crystals obtained in the step d and sodium carbonate decahydrate in the step d according to the proportion of 1:1.5, adding a proper amount of water to prepare a solution with the mass fraction of 28%, stirring, heating to 85 ℃, reacting for 2 hours, adding a surfactant Tween 60 with the mass fraction of 0.5%, and continuing stirring for 15 minutes to uniformly disperse the surfactant.
And standing the obtained product, settling for 20min, pumping out supernatant to separate sodium fluoride and white carbon black, filtering under reduced pressure to obtain sodium fluoride crystals, carrying out centrifugal separation to obtain white carbon black at the rotating speed of 3000 r/min, and respectively drying the obtained sodium fluoride crystals and the obtained white carbon black in an oven at the temperature of 100 ℃ to obtain the sodium fluoride with the purity of 98.5% and the white carbon black with the purity of 96.1%.
Example 3:
100g of waste alkali (the content of sodium carbonate is 67 percent, the content of sodium sulfate is 30 percent) is weighed, 150g of desalted water is added for mixing, the mixture is heated to 55 ℃, and the waste alkali is dissolved by stirring to form waste alkali liquor. Keeping the temperature at 55 ℃, filtering while the solution is hot, and removing insoluble impurities to obtain filtrate A. Cooling the filtrate A to 12 ℃, cooling and crystallizing for 2h, and filtering the fine slurry formed by cooling and crystallizing under reduced pressure to obtain 20g of crystals of sodium carbonate decahydrate and filtrate B.
Adding 18g of fluosilicic acid into the filtrate B under the condition of stirring, and reacting sodium carbonate and sodium sulfate in the filtrate B with the fluosilicic acid to generate sodium fluosilicate and corresponding acid. After the reaction is finished, growing crystals, washing and separating 22g of sodium fluosilicate crystals and filtrate C, and recycling the filtrate C.
Mixing the sodium fluosilicate crystals obtained in the step d and sodium carbonate decahydrate in the step d according to the proportion of 1:1.2, adding a proper amount of water to prepare a solution with the mass fraction of 20%, stirring, heating to 95 ℃, reacting for 2h, adding a surfactant PEG-800 with the mass fraction of 0.3%, and continuing stirring for 15min to uniformly disperse the surfactant.
And standing the obtained product, settling for 15min, pumping out supernatant to separate sodium fluoride and white carbon black, filtering under reduced pressure to obtain sodium fluoride crystals, carrying out centrifugal separation to obtain white carbon black at the rotation speed of 3500 rpm, and respectively drying the obtained sodium fluoride crystals and the white carbon black in an oven at the temperature of 100 ℃ to obtain the sodium fluoride with the purity of 98.6% and the white carbon black with the purity of 96.5%.
Claims (10)
1. A method for preparing sodium fluoride and white carbon black by using caprolactam waste alkali is characterized by comprising the following steps:
1) mixing the waste alkali and desalted water, heating for dissolving, filtering while the mixture is hot, removing insoluble impurities to obtain a filtrate A, and cooling and crystallizing the filtrate A to obtain crystals of sodium carbonate decahydrate and a filtrate B;
2) adding fluosilicic acid into the filtrate B, growing crystals after reaction, and filtering to obtain sodium fluosilicate crystals and filtrate C;
3) mixing the sodium fluosilicate obtained in the step 2) with the sodium carbonate decahydrate obtained in the step 1), adding water, stirring, reacting, and finally adding a surfactant and uniformly mixing;
4) and 3) standing the feed liquid obtained in the step 3) for settling, then pumping out supernatant liquid to separate sodium fluoride and white carbon black, and centrifugally drying to obtain sodium fluoride crystals and white carbon black.
2. The method of claim 1, wherein: the waste alkali in the step 1) comprises, by mass, 60-90% of sodium carbonate, 10-40% of sodium sulfate and 0-2% of insoluble impurities.
3. The method of claim 1, wherein: in the step 1), the waste alkali and the desalted water are mixed according to the weight ratio of 1: 1-2, and the mixture is heated to 35-80 ℃.
4. The method of claim 3, wherein: the temperature for dissolving and filtering in the step 1) is controlled to be 40-60 ℃.
5. The method of claim 1, wherein: when cooling and crystallizing in the step 1), the temperature is 5-30 ℃.
6. The method of claim 5, wherein: when cooling and crystallizing in the step 1), the temperature is 10-20 ℃.
7. The method of claim 1, wherein: the mass fraction of the fluosilicic acid added in the step 2) is 7-15%.
8. The method of claim 1, wherein: mixing sodium fluosilicate and sodium carbonate decahydrate in the step 3) according to the proportion of 1: 1.2-1.5, and adding water to prepare a solution with the mass fraction of 20-30%; the reaction temperature is 85-95 ℃, and when the reaction is finished, a surfactant with the mass fraction of 0.2-0.5% is added, and the mixture is continuously stirred uniformly.
9. The method of claim 1, wherein: the surfactant is span20, Tween 60 or PEG-800.
10. The method of claim 1, wherein: standing in the step 3) for settling for 15-30 min; and respectively drying the sodium fluoride crystal and the white carbon black at the drying temperature of 80-110 ℃.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911370009.0A CN110980743A (en) | 2019-12-26 | 2019-12-26 | Method for preparing sodium fluoride and white carbon black by using caprolactam waste alkali |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911370009.0A CN110980743A (en) | 2019-12-26 | 2019-12-26 | Method for preparing sodium fluoride and white carbon black by using caprolactam waste alkali |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN110980743A true CN110980743A (en) | 2020-04-10 |
Family
ID=70077408
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201911370009.0A Pending CN110980743A (en) | 2019-12-26 | 2019-12-26 | Method for preparing sodium fluoride and white carbon black by using caprolactam waste alkali |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN110980743A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112850722A (en) * | 2021-02-11 | 2021-05-28 | 贵州大学 | Method for preparing white carbon black and cryolite from fluorine-containing silicon slag step by step |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| SU1468643A1 (en) * | 1987-08-19 | 1989-03-30 | Предприятие П/Я Р-6543 | Method of activating bentonite |
| CN1336324A (en) * | 2000-07-29 | 2002-02-20 | 中国石化股份公司巴陵公司 | Sodium carbonate extracting process from caustic lime containing sodium sulfate |
| CN108751227A (en) * | 2018-05-28 | 2018-11-06 | 湖南工业大学 | A kind of production technology producing sodium fluoride co-producing white carbon black using prodan |
| CN108862323A (en) * | 2018-05-28 | 2018-11-23 | 湖南工业大学 | Sodium fluoride co-producing white carbon black is produced using ammonia nitrogen waste water fluorine silicon resource metaplasia with high salt |
-
2019
- 2019-12-26 CN CN201911370009.0A patent/CN110980743A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| SU1468643A1 (en) * | 1987-08-19 | 1989-03-30 | Предприятие П/Я Р-6543 | Method of activating bentonite |
| CN1336324A (en) * | 2000-07-29 | 2002-02-20 | 中国石化股份公司巴陵公司 | Sodium carbonate extracting process from caustic lime containing sodium sulfate |
| CN108751227A (en) * | 2018-05-28 | 2018-11-06 | 湖南工业大学 | A kind of production technology producing sodium fluoride co-producing white carbon black using prodan |
| CN108862323A (en) * | 2018-05-28 | 2018-11-23 | 湖南工业大学 | Sodium fluoride co-producing white carbon black is produced using ammonia nitrogen waste water fluorine silicon resource metaplasia with high salt |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112850722A (en) * | 2021-02-11 | 2021-05-28 | 贵州大学 | Method for preparing white carbon black and cryolite from fluorine-containing silicon slag step by step |
| CN112850722B (en) * | 2021-02-11 | 2022-10-14 | 贵州大学 | Method for preparing white carbon black and cryolite from fluorine-containing silicon slag step by step |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN102050487B (en) | Acidolysis method in titanium dioxide production technology adopting sulfuric acid process | |
| WO2018041272A1 (en) | Method for preparing industrial grade lithium carbonate from crude lithium fluoride, and a lithium carbonate product | |
| CN111186852B (en) | Process for purifying quartz material and preparing aluminum fluoride and high-purity white carbon black by using byproduct fluosilicic acid | |
| CN110642282A (en) | Method for preparing calcium fluoride and potassium bicarbonate by using carbon dioxide | |
| CN110980743A (en) | Method for preparing sodium fluoride and white carbon black by using caprolactam waste alkali | |
| CN108928825B (en) | Method for separating and recovering silicon dioxide and ammonium fluosilicate from fluorine-containing dust | |
| CN114195315A (en) | Method for combined treatment of acidic and non-acidic copper-containing etching waste liquid, tin stripping waste liquid and copper nitrate waste liquid | |
| CN113371749A (en) | Method for treating calcium-containing sludge in semiconductor industry | |
| CN115893449B (en) | Method for producing electronic grade sodium fluoride by using industrial grade sodium-alkali mixed solution | |
| CN106517289A (en) | Method of using low-grade witherite to produce high-purity barium chloride | |
| CN105480959A (en) | Method for producing monopotassium phosphate by fluoride salt purification process | |
| US2475287A (en) | Henry c | |
| CN104445281A (en) | Waste residue comprehensive utilization method for trichlorosilane leaching system | |
| CN1234596C (en) | Process for preparing fluorine compound and SiO2 from sodium fluosilicate | |
| US3416887A (en) | Method of manufacturing wet process phosphoric acid | |
| CN110304850A (en) | A method of alpha semi-hydrated gypsum is produced based on titanium gypsum | |
| CN104386711B (en) | Wet defluorination of phosphoric acid slag prepares the method for sodium fluoride | |
| JPH03204844A (en) | Recovery of glycine and glauber's salt from waste crystal liquid | |
| CN104591189B (en) | Recycling method for purifying cryolite waste acid | |
| CN114014287A (en) | Wet-process phosphoric acid purification method | |
| CN113772707A (en) | Treatment method of fluorine-containing potassium chloride | |
| CN106744996A (en) | A kind of Ludox and preparation method thereof | |
| CN113277937A (en) | Method for refining crude benzoic acid | |
| US3005685A (en) | Process for desilicifying fluorspar and the like minerals | |
| CN104630877B (en) | Method for preparing calcium sulfate dihydrate whisker from tin-smelting waste slag |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| RJ01 | Rejection of invention patent application after publication | ||
| RJ01 | Rejection of invention patent application after publication |
Application publication date: 20200410 |