CN109665551A - A method of ice crystal is prepared using phosphoric acid industry exhaust gas - Google Patents
A method of ice crystal is prepared using phosphoric acid industry exhaust gas Download PDFInfo
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- CN109665551A CN109665551A CN201710963410.XA CN201710963410A CN109665551A CN 109665551 A CN109665551 A CN 109665551A CN 201710963410 A CN201710963410 A CN 201710963410A CN 109665551 A CN109665551 A CN 109665551A
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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
- C01B33/113—Silicon oxides; Hydrates thereof
- C01B33/12—Silica; Hydrates thereof, e.g. lepidoic silicic acid
- C01B33/18—Preparation of finely divided silica neither in sol nor in gel form; After-treatment thereof
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- 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
- C01F7/00—Compounds of aluminium
- C01F7/48—Halides, with or without other cations besides aluminium
- C01F7/50—Fluorides
- C01F7/54—Double compounds containing both aluminium and alkali metals or alkaline-earth metals
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Abstract
A method of ice crystal is prepared using phosphoric acid industry exhaust gas, the waste gas containing fluoride generated in the molten process phosphoric acid processed of rock phosphate in powder acid is absorbed using sodium bicarbonate solution, hydrogen fluoride and reaction of sodium bicarbonate in fluoro-gas is set to generate sodium fluoride, SiF4 and reaction of sodium bicarbonate in fluoro-gas is set to generate sodium fluoride and silica gel, silica gel is precipitated in the form of hydrated SiO 2, the active silica (white carbon black) of high-ratio surface can be made after filtration drying, calcining.After filtrate (Fluorinse) mixes with sodium aluminate solution, being passed through carbon dioxide gas can be obtained by the cryolite of high molecule ratio, and up to product ice crystal after filtering, drying, which is known as Crystallization Procedure.The sodium bicarbonate solution generated in this process, which can return to, absorbs process repetition absorption fluoro-gas.The Fluorine contained chemicals of high added value can be prepared using waste gas containing fluoride --- ice crystal.
Description
Technical field:
The present invention is that waste gas containing fluoride prepares cryolite with high molecular ratio and by-product white carbon black in a kind of comprehensive utilization production process of phosphoric acid
Production method, belong to field of inorganic chemical engineering.
Background technique:
Phosphoric acid is using rock phosphate in powder as raw material, obtaining with inorganic acid (such as sulfuric acid, hydrochloric acid) generation metathesis reaction.Rock phosphate in powder
Main component be fluor-apatite (Ca5F (PO4) 3), the fluorine element in rock phosphate in powder can in the form of HF gas in acid hemolysis process
It releases, is separately partly dissolved the SiO2 effect dissolved in HF and rock phosphate in powder in the liquid phase in the liquid phase and generates SiF4,
SiF4 also can be cooked out in gaseous form during subsequent Phosphoric Acid Concentration.Therefore it can be generated in phosphoric acid industry big
Measure the exhaust gas containing HF and SiF4.Since both gases belong to toxic, pernicious gas, it is necessary to after being pocessed
It can discharge, otherwise will cause serious atmosphere pollution.
Phosphoric acid industry is mostly to be absorbed to obtain hydrofluoric acid and fluosilicic acid with water for the method for fluoro-gas at present, due to hydrogen fluorine
Acid and fluosilicic acid are not readily separated, and industrial is typically all in being neutralized to the mixed solution of fluosilicic acid and hydrofluoric acid with lime stone
Property, it is distributed hydrofluoric acid and fluosilicic acid and becomes calcirm-fluoride and calcium fluosilicate precipitating, precipitating filtering is then formed into fluorine-containing waste residue,
Or in spent lye and the mixed solution of hydrofluoric acid and fluosilicic acid, being allowed to become sodium fluoride and prodan precipitating, will precipitate
After filter, waste liquid direct emission (since sodium fluoride is slightly soluble in water, still contains a certain amount of fluorine in waste liquid).Though in this way
Fluoro-gas pollution caused by atmosphere is so avoided, but produces the pollution of waste residue and/or waste liquid simultaneously.
Summary of the invention:
It is high additional the object of the invention is to be prepared at low cost using the waste gas containing fluoride generated in phosphorus ore process phosphoric acid made of stones
The Fluorine contained chemicals of value --- cryolite with high molecular ratio, to realize the recycling of fluorine resource in rock phosphate in powder, and with white carbon black
Form recycles the elemental silicon in fluoro-gas.
The present invention absorbs the waste gas containing fluoride generated in the molten process phosphoric acid processed of rock phosphate in powder acid using sodium bicarbonate solution, makes fluorine-containing
Hydrogen fluoride and reaction of sodium bicarbonate in gas generate sodium fluoride, generate SiF4 and reaction of sodium bicarbonate in fluoro-gas
Sodium fluoride and silica gel, this step are known as absorbing process.Sodium fluoride is set to be dissolved in liquid phase by controlling solution concentration in the process
In, by adjusting the pH value of absorbing liquid, silica gel is precipitated in the form of hydrated SiO 2, it can after filtration drying, calcining
The active silica (white carbon black) of high-ratio surface is made.After filtrate (Fluorinse) mixes with sodium aluminate solution, lead to
Entering carbon dioxide gas can be obtained by the cryolite of high molecule ratio, up to product ice crystal, the process after filtering, drying
Referred to as Crystallization Procedure.The sodium bicarbonate solution generated in this process, which can return to, absorbs process repetition absorption fluoro-gas.In addition
The carbon dioxide gas generated in absorbing process can also return to Crystallization Procedure and be used to prepare cryolite, such bicarbonate
Sodium and carbon dioxide realize closed cycle, in the case where operation reaches and stablizes, it is only necessary to it is molten to supplement part sodium bicarbonate
Liquid.Sodium metaaluminate can be reacted by aluminium hydroxide with sodium hydroxide to prepare, and only be needed in this way with aluminium hydroxide, hydrogen
Sodium oxide molybdena and a small amount of sodium bicarbonate are raw material, are produced using the fluorination work that waste gas containing fluoride can prepare high added value
Product --- ice crystal.
The principle of the technical solution can be illustrated with following reaction equation:
Absorption process: HF+NaHCO3 → NaF+H2O+CO2 ↑
SiF4+4NaHCO3→4NaF+Si(OH)4↓+4CO2↑
Crystallization Procedure: Al (OH) 3+NaOH → NaAlO2+2H2O
6NaF+NaAlO2+2CO2→Na3AlF6↓+2Na2CO3
Na2CO3+CO2+H2O→2NaHCO3
It is also reacted with CO2 in the excessive NaOH of Crystallization Procedure and generates sodium carbonate, and further reacted with CO2 and generate sodium bicarbonate,
Reaction equation is as follows:
2NaOH+CO2→Na2CO3+H2O
Na2CO3+CO2+H2O→2NaHCO3
The NaHCO3 of generation can replace CO2 and sodium fluoride and sodium metaaluminate effect generates ice crystal, and reaction equation is as follows:
6NaF+4NaHCO3+NaAlO2→Na3AlF6↓+4Na2CO3+2H2O
The specific embodiment of the technology is as follows:
Waste gas containing fluoride is introduced in packed absorber first, the carbon that 5~10% sodium bicarbonate solution and crystallization section are recycled
Sour hydrogen sodium solution is sprayed into tower by spray head.The pH of tower solution is used between 7~8 by adjusting reflux ratio (liquid-gas ratio).pH
When value > 8, the solubility of silica gel in the solution increases, and causes to be mixed with more SiO2 in ice crystal, while the particle of silica gel is thin
It is small, it is difficult to filter, but at this moment white carbon black large specific surface area obtained；When pH value < 7, fluoro-gas is absorbed insufficient, tail
Contain more SiF4 in gas, it is inclined that the SiF4 hydrolysis in Crystallization Procedure, tail gas equally will cause SiO2 content in ice crystal
It is high.Solution is warming up to 80~90 DEG C after going out tower, and then the poly- propionyl enamine of addition 0.05~0.1% is as flocculant, heat preservation
It is filtered after being cooled to room temperature after 2~3h with 10~20 DEG C/h, precipitate washed with water 2~4 times, cleaning solution imports in filtrate, sinks
Starch at 250~300 DEG C calcines 2~3h and can be prepared by specific surface area and be first at 105~120 DEG C after dry 1~3h
The active silica (white carbon black) of 100~200m2/g.The specific surface area and neutralization step pH value relationship of active silica
As shown in table 1.
Aluminium hydroxide is dissolved in be made into 20% sodium hydroxide solution~30% or so sodium aluminate solution, then
The sodium aluminate solution prepared is added to while stirring in filtered absorbing liquid, solution is warming up to 80~90 DEG C, simultaneously
It blasts air or absorbs the carbonated exhaust gas that process generates, control the air-blowing time, the pH of solution is made to drop to 8~9
Afterwards, it is filtered after keeping the temperature 2~3h, filter cake is washed 2~3 times with clear water, up to high molecule ratio after 110~130 DEG C of dry 2~5h
Ice crystal, filtrate contains the solution of a certain amount of sodium bicarbonate and a small amount of sodium fluoride, which can return to absorption section weight
It is new to absorb fluoro-gas.The molecular proportion (molar ratio of NaF and AlF3) and feed way of ice crystal have much relations, by inclined aluminium
Acid sodium solution is added in Fluorinse, and guarantees sodium fluoride excessively and the ice crystal of high molecule ratio can be obtained.Point of ice crystal
Son ratio is with the relationship between sodium fluoride excess referring to table 2.
This technology invention has the advantage that
1. not only having avoided pollution of the fluoro-gas to environment, but also take full advantage of fluorine resource using waste gas containing fluoride as raw material.
2. height can be prepared by simple technique using cheap sodium bicarbonate, sodium hydroxide and aluminium hydroxide as raw material
The ice crystal of added value.
It is recycled 3. sodium bicarbonate and carbon dioxide gas realize, reduces raw materials consumption as much as possible.
4. the characteristics of absorbing waste gas containing fluoride using sodium bicarbonate, being slightly soluble in water using sodium fluoride, hydrogen fluoride is become to be fluorinated
Sodium is dissolved in water, and SiF4 then becomes precipitation of silica and sodium fluoride, so that silicon is separated with fluorine, it is not necessary to thing
First HF is separated with SiF4 phase.
5. the pH value of absorption process can be flexibly controlled by changing sodium bicarbonate solution concentration and reflux ratio, in this way
It can be obtained by the stable high activity white carbon black of quality.
6. the ice crystal of high molecule ratio can be prepared by changing feed way and improving the excessive percentage of sodium fluoride,
Excessive sodium fluoride can also be utilized again by feed liquid circulation simultaneously.
7. using packed absorber, containing in phosphoric acid industry can be efficiently absorbed using sodium bicarbonate solution as absorbing liquid
Fluorine gas, absorptivity is up to 99% or more.
8. advantages of nontoxic raw materials, harmless, corrosion-free, non-stimulated, and without exhaust gas, waste residue, waste liquid in entire production process
Discharge, belongs to a kind of green production process.
Specific embodiment:
Embodiment 1
The waste gas containing fluoride that will be made of 2.5% (volume ratio) HF and 1.7% (volume ratio) SiF4 and air uses ceramic raschig rings
Packed tower is absorbed with 5% sodium bicarbonate solution.Reflux ratio=5 are controlled, make the pH=7.5 of absorbing liquid, tail gas is after detecting
Containing HF 0.023%, contain SiF4 0.028%, that is, 99.1% has been reached to the absorptivity of HF, the absorptivity of SiF4 is reached
98.4%.Absorbing liquid is warming up to 90 DEG C, the poly- propionyl enamine of sediment total amount 0.05% is added into solution as flocculation
Agent is cooled to 30 DEG C of filterings after keeping the temperature 2h with the cooling rate of 15 DEG C/h, and filter residue is washed 2 times, then dry at 110 DEG C
2h is that 3h is calcined at 250 DEG C can be prepared by the white carbon black that specific surface area is 147m2/g.Then by the hydrogen-oxygen of theoretical amount 95%
Change aluminium to react to obtain 28% sodium aluminate solution with 20% sodium hydroxide solution, by sodium metaaluminate under the action of stirring
Solution is poured slowly into Fluorinse, guarantees Fluorinse excessive 20%, solution is warming up to 90 DEG C, blasts and carrys out self-priming
The tail gas or air of tower are received, the air-blowing time is controlled, makes the pH=8.3 of solution, be aged 2h after air-blowing, be down to room to solution
It is filtered after temperature, filter residue is washed 2 times, and the ice crystal that then dry 3h is 2.93 up to molecular proportion at 120 DEG C, filtrate then returns
It repeats to absorb fluoro-gas in absorption tower.
Claims (6)
1. a kind of method for preparing ice crystal using phosphoric acid industry exhaust gas, which is characterized in that the present invention uses sodium bicarbonate solution
The waste gas containing fluoride generated in the molten process phosphoric acid processed of rock phosphate in powder acid is absorbed, the hydrogen fluoride and reaction of sodium bicarbonate in fluoro-gas are made
Sodium fluoride is generated, SiF4 and reaction of sodium bicarbonate in fluoro-gas is made to generate sodium fluoride and silica gel, this step is known as absorbing work
Sequence makes sodium fluoride dissolution in the liquid phase by controlling solution concentration in the process, by adjusting the pH value of absorbing liquid, makes silica gel
It is precipitated in the form of hydrated SiO 2, the active silica that high-ratio surface can be made after filtration drying, calcining is white
Carbon black.
2. a kind of method for preparing ice crystal using phosphoric acid industry exhaust gas according to claim 1, which is characterized in that filtrate
After Fluorinse is mixed with sodium aluminate solution, being passed through carbon dioxide gas can be obtained by the cryolite of high molecule ratio,
Up to product ice crystal after filtering, drying, which is known as Crystallization Procedure.
3. a kind of method for preparing ice crystal using phosphoric acid industry exhaust gas according to claim 1, which is characterized in that herein
The sodium bicarbonate solution generated in process, which can return to, absorbs process repetition absorption fluoro-gas, in addition generates in absorbing process
Carbon dioxide gas can also return to Crystallization Procedure and be used to prepare cryolite, such sodium bicarbonate and carbon dioxide are realized
Closed cycle, in the case where operation reaches and stablizes, it is only necessary to supplement part sodium bicarbonate solution.
4. a kind of method for preparing ice crystal using phosphoric acid industry exhaust gas according to claim 1, which is characterized in that inclined aluminium
Sour sodium can be reacted by aluminium hydroxide with sodium hydroxide to prepare, and only be needed in this way with aluminium hydroxide, sodium hydroxide and a small amount of
Sodium bicarbonate be raw material, the Fluorine contained chemicals of high added value can be prepared using waste gas containing fluoride --- ice crystal.
5. a kind of method for preparing ice crystal using phosphoric acid industry exhaust gas according to claim 1, which is characterized in that first
Waste gas containing fluoride is introduced in packed absorber, the sodium bicarbonate that 5~10% sodium bicarbonate solution and crystallization section are recycled is molten
Liquid is sprayed into tower by spray head, uses the pH of tower solution between 7~8 by adjusting reflux ratio (liquid-gas ratio), when pH value > 8,
The solubility of silica gel in the solution increases, and causes to be mixed with more SiO2 in ice crystal, while the particle of silica gel is tiny, it is difficult to
Filtering, but at this moment white carbon black large specific surface area obtained；When pH value < 7, fluoro-gas is absorbed insufficient, contains in tail gas
There is more SiF4, it is higher that the SiF4 hydrolysis in Crystallization Procedure, tail gas equally will cause SiO2 content in ice crystal.
6. a kind of method for preparing ice crystal using phosphoric acid industry exhaust gas according to claim 1, which is characterized in that molten
Liquid is warming up to 80~90 DEG C after going out tower, and then the poly- propionyl enamine of addition 0.05~0.1% keeps the temperature 2~3h as flocculant
It is filtered after being cooled to room temperature afterwards with 10~20 DEG C/h, precipitate washed with water 2~4 times, cleaning solution imports in filtrate, sediment
First at 105~120 DEG C after dry 1~3h, calcined at 250~300 DEG C 2~3h can be prepared by specific surface area be 100~
The active silica of 200m2/g, aluminium hydroxide is dissolved in be made into 20% sodium hydroxide solution~30% or so it is inclined
Then the sodium aluminate solution prepared is added in filtered absorbing liquid while stirring, solution is heated up by sodium aluminate solution
It to 80~90 DEG C, while blasting air or absorbing the carbonated exhaust gas that process generates, control the air-blowing time, make solution
PH drop to 8~9 after, keep the temperature 2~3h after filter, filter cake is washed 2~3 times with clear water, 110~130 DEG C of dry 2~5h with
Afterwards up to the ice crystal of high molecule ratio, filtrate contains the solution of a certain amount of sodium bicarbonate and a small amount of sodium fluoride, which can return
It returns to absorption section and reuptakes fluoro-gas, the molecular proportion (molar ratio of NaF and AlF3) and feed way of ice crystal have very
Sodium aluminate solution is added in Fluorinse by Important Relations, and guarantees sodium fluoride excessively and the ice crystal of high molecule ratio can be obtained
Stone.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112480729A (en) * | 2020-12-08 | 2021-03-12 | 浙江睿光节能科技有限公司 | Double-component outer wall thin heat insulation material and use method thereof |
| 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 |
-
2017
- 2017-10-17 CN CN201710963410.XA patent/CN109665551A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112480729A (en) * | 2020-12-08 | 2021-03-12 | 浙江睿光节能科技有限公司 | Double-component outer wall thin heat insulation material and use method thereof |
| 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 |
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