CN108285161A - A kind of preparation process of magnesium fluoride - Google Patents
A kind of preparation process of magnesium fluoride Download PDFInfo
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- CN108285161A CN108285161A CN201810239313.0A CN201810239313A CN108285161A CN 108285161 A CN108285161 A CN 108285161A CN 201810239313 A CN201810239313 A CN 201810239313A CN 108285161 A CN108285161 A CN 108285161A
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- magnesium
- magnesium hydroxide
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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
- C01F5/00—Compounds of magnesium
- C01F5/26—Magnesium halides
- C01F5/28—Fluorides
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Abstract
The invention discloses a kind of preparation processes of magnesium fluoride, include the following steps：Step S1：The magnesium hydroxide filter cake formed in lithium technique is carried using salt lake bittern as raw material, is cleaned to it, to extract magnesium hydroxide material, Cl in magnesium hydroxide material‑Mass fraction be 0.001% or less；Step S2：Magnesium hydroxide material is mixed with hydrofluoric acid, neutralization reaction occurs and forms magnesium fluoride；Step S3：The first body of magnesium fluoride crystallization of formation is through separating, washing process, drying process, magnesium fluoride crystal is made, the present invention obtains magnesium fluoride crystal best in quality, suitable for optical lens plated film, in ceramics, the use of electronics industry, waste magnesium hydroxide filter cake is carried in lithium production process as raw material using salt lake bittern, both the burial of the waste magnesium hydroxide filter cake in brine puies forward lithium technique had been solved the problems, such as, and effectively save the manufacturing cost of magnesium fluoride crystal, technical process is simple, low energy consumption, meets the theory of green circulation economy.
Description
Technical field
The present invention relates to technical fields prepared by magnesium fluoride, and in particular to a kind of to propose lithium generation in the process using salt lake bittern
Discarded magnesium hydroxide filter cake production magnesium fluoride crystal preparation process.
Background technology
Magnesium fluoride, molecular formula MgF2, relative molecular mass 62.3.Colourless crystallization or white powder, lattice of rutile type are micro-
There is purple fluorescence.It is atomic to be dissolved in water (18 DEG C, 87mg/L), it is slightly soluble in diluted acid (especially nitric acid).Relative density 3.18.Fusing point
1248℃.2260 DEG C of boiling point.It is toxic, it is irritant.Heating is in weak purple fluorescence under electric light, and crystal has good polarization
Effect, particularly suitable for ultraviolet light and infrared spectrum.Purposes：Optical lens plated film.Optical equipment plates last layer magnesium fluoride film layer, can
To reduce reflection of the camera lens interface to injection light, halation is reduced, image quality is improved.In addition magnesium fluoride be also applied to ceramics,
Electronics industry；Manufacture ceramics, glass；The fluxing agent of metallurgical magnesium metal；The fluorescent material of cathode-ray screen；Solder flux etc..
Main production process：
1. carbonic acid magnesium processes：It is mostly dolomite or magnesite that magnesium carbonate method, which prepares magnesium source used in magnesium fluoride,.Reaction equation is：
MgCO3+2HF— MgF2+CO2 +H2O
Magnesium carbonate method prepares magnesium fluoride technical process (using magnesite as raw material)：1）Magnesite powder slurries are added in hydrofluoric acid
In, it is stirred to react a period of time, obtains magnesium fluoride slurries；It is vented after escaping gas processing.2) magnesium fluoride slurries are filtered
, filter residue is washed, dry, obtains fluorination magnesium products；Filtrate portion is used for miberal powder pulp, partly send treatment trough with dilute carbonic acid
Magnesium neutralisation treatment is discharged after up to standard.
Magnesium sulfate 2. (or magnesium nitrate) method：It is to be with magnesium sulfate or magnesium nitrate that magnesium sulfate (or magnesium nitrate) method, which prepares magnesium fluoride,
Raw material, the reaction equation being related to are as follows：
MgSO4+2NaOH—Mg(OH)2+Na2SO4
Mg(OH)2+2HF=MgF2+2H2O
2NaF2+MgSO4—Na2SO4+MgF2
Magnesium sulfate (or magnesium nitrate) method prepares magnesium fluoride technical process (using magnesium sulfate as raw material)：1) aqueous magnesium sulfate is carried out
Pretreatment removes some impurity of the inside；2) magnesium sulfate being reacted with alkali, intermediate product obtained is washed, filters,
It is placed in lining with lead or the reactor of lining plastic, is reacted while stirring with excessive hydrofluoric acid, this reaction needs to keep certain two
Carbonoxide divides；3) after completion of the reaction, by material washing, drying, crushing, the fluorination magnesium products of high-purity are obtained.
3. magnesium oxide method：It is using magnesia as raw material that magnesium oxide method, which prepares magnesium fluoride, and reaction equation is as follows：2 HF + MgO
— MgF2 + H2O
Magnesium fluoride technical process is prepared by raw material of magnesia：1) high-purity magnesium oxide that mass fraction is 99.99% is placed in platinum
In crucible, the pure hydrofluoric acid of analysis for being 40% with mass fraction is tempered, and the two is made to react, and obtains fluorination magma magnesiae 2) it will
It is fluorinated magma magnesiae to refine, filter, then dries, crushes, obtain high-purity fluorination magnesium products.
4. magnesium chloride process：
Halogen water-ammonia-hydrogen fluoride：It is using magnesium chloride, ammonia as raw material that halogen water-ammonia-hydrogen fluoride, which prepares magnesium fluoride, and reaction equation is such as
Under：
MgC12 +2NH 3+ 2H 2O — Mg(OH)2 + 2NH4C1
Mg(OH)2 + 2HF — MgF2 + 2H 2O
Halogen water-ammonia-hydrogen fluoride prepares magnesium fluoride technical process：1) by MgC12：It is configured to brine, people is then led into solution
Ammonia generates Mg (OH)2Precipitation, filtering, obtains Mg (OH)2Filter cake is crushed and 2) is added into the filter cake crushed by filter cake
Slightly excessive hydrofluoric acid removes the HF of absorption, drying to MgF after completion of the reaction by material filtering, washing2, finished product.
Ammonium fluoride-magnesium chloride process：It is using ammonium fluoride and magnesium chloride as raw material, instead that ammonium fluoride-magnesium chloride process, which prepares magnesium fluoride,
Answer formula as follows：2 NH4F + MgC12——MgF2 + 2NH4 C1
Ammonium fluoride monochlor(in)ate magnesium processes prepare magnesium fluoride technical process：1) by mass fraction be 30%-45% ammonium fluoride solution and
The magnesium chloride solution that mass fraction is 25%~36% is added in reaction kettle simultaneously, and magnesium fluoride slurry is obtained after reaction, is filtered
To magnesium fluoride ointment 2) magnesium fluoride ointment is washed with 60-70 DEG C of hot water, then dry 1~2 at 250-400 DEG C
H is crushed and is obtained magnesium fluoride finished product.
Due to the magnesium ion containing higher concentration in salt lake bittern, a large amount of magnesium ion is still had in putting forward lithium technique and is existed
In lithium desorption liquid, during handling lithium desorption liquid, usually converts magnesium hydroxide and formed through press filtration magnesium ion to and filter
Cake and remove.Although magnesium hydroxide material be have in generally acknowledged at present rubber and plastic industry fire-retardant, suppression cigarette, filling triple functions it is excellent
It is contour to be widely used in rubber, chemical industry, building materials, plastics and electronics, unsaturated polyester (UP) and paint, coating for elegant flame retardant materials
In molecular material, but the magnesium hydroxide filter cake handled in the technique that salt lake bittern carries lithium is since its content is not high, knot
Crystalline form looks and dispersibility do not meet the requirement as filler and fire retardant and would generally directly be discarded, and a large amount of wastes are covered
It buries, has not only increased and buried cost but also cause the wasting of resources.It therefore, if can be by the discarded magnesium hydroxide filter cake using producing
Magnesium fluoride can solve the problems, such as that the manufacturing cost of magnesium fluoride, symbol are buried and effectively reduced to the discarded magnesium hydroxide filter cake
Close the theory of green circulation economy.
Invention content
The purpose of the present invention is to provide a kind of preparation processes of magnesium fluoride, have the advantages of economizing on resources, solve salt
During lake bittern water carries lithium, the discarded of magnesium hydroxide filter cake not only increases the problem of burying cost simultaneously but also resulting in waste of resources,
The problem of all bringing about great losses to manufacturing enterprise and environment.
To achieve the goals above, the present invention provides the following technical solutions：A kind of preparation process of magnesium fluoride, feature exist
In：Include the following steps：
Step S1：The magnesium hydroxide filter cake formed in lithium technique is carried using salt lake bittern as raw material, to the magnesium hydroxide filter cake
Removal of impurities processing is carried out, to extract the magnesium hydroxide material in the magnesium hydroxide filter cake, Cl in the magnesium hydroxide material-'s
Mass fraction is 0.001% or less；
Step S2：It is according to the ratio between the amount of substance of magnesium hydroxide and hydrofluoric acid with hydrofluoric acid solution by the magnesium hydroxide material
2.7-2.8：1 mixing, according to reaction equation：Mg(HO)2+2HF= MgF2+2H2O occurs neutralization reaction and forms magnesium fluoride；
Step S3：Just magnesium fluoride crystal is made through separating, washing process, drying process in body for the magnesium fluoride crystallization.
Preferably, the source of the magnesium hydroxide filter cake in the step S1 is to carry in lithium technique being formed from salt lake bittern, is walked
The removal of impurities treatment process in rapid S1 includes the following steps：
1）The magnesium hydroxide filter cake is added in make-up tank, water is added into configured slot, is stirred, form the first thick shape
Object；
2）First thick liquid is heated to after 40 ~ 50 DEG C, and the temperature of first thick liquid is maintained at 40 ~ 50 DEG C and is stirred
First thick liquid, 20 ~ 40min is mixed, the second thick liquid is formed；
3）By second thick liquid through filter press to form the second filter cake.
Preferably, the temperature setting of first thick liquid is 47 DEG C, and the temperature of the first thick liquid is maintained at 47
The first thick liquid 30min is stirred at DEG C.
Preferably, using desalted water to step 3）In second Washing of Filter Cake, to form third filter cake and as step
The magnesium hydroxide material in rapid S2 uses.
Preferably, during the neutralization reaction carries out, reaction temperature controls between 85 ~ 90 DEG C step S2.
Preferably, the reaction temperature is arranged at 88 DEG C.
Preferably, at the end, the pH value of the reaction solution of formation is between 4.5 ~ 5 for neutralization reaction described in step S2.
Preferably, the pH value of the reaction solution of the formation is 4.8.
Preferably, the drying process in step S3 is pneumatic conveying drying, and the drying temperature in the pneumatic conveying drying is
98 DEG C, pressure is less than 0.01MPa, air-flow velocity 70km/h.
Compared with the prior art, the preparation process of magnesium fluoride of the present invention has the advantage that：Institute through the invention
Magnesium fluoride crystal best in quality can be prepared in the preparation process for the magnesium fluoride stated, and be suitable for optical lens plated film, in ceramics, electricity
The use of sub- industry.The present invention carries waste magnesium hydroxide filter cake in lithium production process using salt lake bittern and was both solved as raw material
It has determined the burial problem of in brine puies forward lithium technique waste magnesium hydroxide filter cake, and has effectively saved the system of magnesium fluoride crystal
Standby cost.Meanwhile the preparation process of magnesium fluoride provided by the present invention is simple, low energy consumption, meets green circulation economy
Theory.
Specific implementation mode
The present invention provides many applicable creative concepts, which can be reflected in a large number of on specific
Hereinafter.Specific embodiment described in following embodiments of the present invention is only as the specific implementation mode of the present invention
Exemplary illustration, and be not meant to limit the scope of the invention.
With reference to specific embodiment, the invention will be further described.
Embodiment one：The present embodiment provides a kind of preparation processes of magnesium fluoride, include the following steps：
Step S1：Using magnesium hydroxide filter cake as raw material, removal of impurities processing is carried out to magnesium hydroxide filter cake, to extract magnesium hydroxide
In order to improve the purity of the present embodiment final product, institute specifically is handled by above-mentioned removal of impurities for magnesium hydroxide material in filter cake
Cl in the magnesium hydroxide material of formation-Mass fraction require below 0.001%.
In the magnesium hydroxide filter cake, main matter is magnesium hydroxide, also contains partial oxidation sodium and a small amount of unreacted magnesium
Ion is formed by chlorination magnesium addition, and therefore, the present embodiment realizes removal of impurities processing to the magnesium hydroxide filter cake first.It should remove and live together
The removal of impurities modes such as multistep washing filtering can be used in reason, it is preferred that difference of the present embodiment by magnesium hydroxide and impurity in water
Solubility handles it, and efficiently quick and good impurity removing effect, specific dedoping step are as follows for the removal of impurities processing procedure：
1）Magnesium hydroxide filter cake is added in make-up tank, water is added into configured slot, is stirred, formed the first thick liquid, be
It is convenient for the control of finishing operations, the mass fraction of water is 70% in first thick liquid, and the temperature setting of the first thick liquid is 47
DEG C, and the temperature of the first thick liquid is maintained at 47 DEG C and stirs the first thick liquid 30min,
2）The first thick liquid is heated to after 40 ~ 50 DEG C, and it is thick that the temperature of the first thick liquid is maintained at stirring first at 40 ~ 50 DEG C
Shape 20 ~ 40min of object forms the second thick liquid；
The mode of heating is preferably steam heating, by the steam distributor being arranged in equipment, to realize to material in equipment
Heating, so that heating process is more economical and simple, it is also more convenient for the control of temperature.The material of first thick liquid
Liquid temperature remains 40 ~ 50 DEG C, if since temperature is too low, is not easy rapidly in the sodium chloride of crystal form and magnesium chloride in filter cake
Be dissolved into liquid phase, and if temperature is excessively high, not only waste thermal energy, and can operate and brought not to the press filtration in later steps
Just, operator's scald is easily caused, meanwhile, within this temperature range, the close maximum of solubility of sodium chloride, therefore, this implementation
Example can realize preferable impurity-eliminating effect to the control of feed temperature, and conducive to the progress of subsequent step.
3）By the second thick liquid through filter press to form the second filter cake, which is above-mentioned magnesium hydroxide material.
Filter press is a kind of common solid-liquid separating equipment of chemical industry, is to utilize special filter medium, to filtering
Object applies certain pressure so that a kind of mechanical equipment that liquid dialysis comes out.Specifically, the filter press in the present embodiment is adopted
It is plate and frame filter press.
In order to further enhance the purity of magnesium hydroxide in the second filter cake, the present embodiment using the second filter cake of desalted water pair into
The third filter cake, to which third filter cake be made, is used as hydrogen by row washing to further decrease the content of chlorion in the second filter cake
Magnesia material can further promote the purity of the final product magnesium fluoride crystal obtained by the later stage.
Step S2：By magnesium hydroxide material with hydrofluoric acid solution according to the ratio between the amount of substance of magnesium hydroxide and hydrofluoric acid
For:1.35-1.45：1 mixing, according to reaction equation：Mg(HO)2+2HF= MgF2+2H2O occurs neutralization reaction and generates fluorination
Magnesium.
During neutralization reaction carries out, reaction temperature controls between 85 ~ 90 DEG C, and wherein reaction temperature is set as 88
DEG C, during above-mentioned neutralization reaction occurs, if reaction temperature is too low, is unfavorable for crystal and grows up, if conversely, reaction temperature too
Height is then easy that unreacted HF is made to volatilize, and increases cooling difficulty, and therefore, the temperature that the present embodiment controls reaction solution is 85 ~ 90
DEG C, in reaction time 2-3 hour, the reaction later stage is slowly stirred or static processing, keeps crystal grain more perfect, neutralization reaction is terminating
When, the pH value of the reaction solution of formation is between 4.5 ~ 5, and wherein the pH value of reaction solution is 4.8.
Specifically, since the neutralization reaction in this step is exothermic reaction, the present embodiment is used is arranged folder on reaction kettle
Set, uses and allows cooling water by way of chuck to control the reaction temperature in this step.
Step S3：Magnesium fluoride crystalline solid is through separation process, drying process, and to which magnesium fluoride crystal be made, drying process is
Pneumatic conveying drying, the drying temperature in pneumatic conveying drying are 98 DEG C, and pressure is less than 0.01MPa, air-flow velocity 70km/h.
It is separated using centrifugal separation process to which magnesium fluoride is crystallized just body, is used in combination desalted water to crystalline solid into traveling
The washing of one step, the liquid after separation process can be discharged or be returned it in reactor, then participate in neutralization reaction, using desalination
Water is to step 3）In the second Washing of Filter Cake, to form third filter cake and be used as the magnesium hydroxide material in step S2.
Just body realizes it by the way of pneumatic conveying drying drying process for isolated magnesium fluoride crystallization, pneumatic conveying drying
Mode is that the dispersion of scattered particulate solid material is suspended in velocity heated gas, a kind of method being dried under Geldart-D particle.
Embodiment two：The present embodiment provides a kind of preparation processes of magnesium fluoride, include the following steps：
Step S1：Using magnesium hydroxide filter cake as raw material, removal of impurities processing is carried out to magnesium hydroxide filter cake, to extract magnesium hydroxide
In order to improve the purity of the present embodiment final product, institute specifically is handled by above-mentioned removal of impurities for magnesium hydroxide material in filter cake
Cl in the magnesium hydroxide material of formation-Mass fraction require below 0.001%.
In the magnesium hydroxide filter cake, main matter is magnesium hydroxide, also contains partial oxidation sodium and a small amount of unreacted magnesium
Ion is formed by chlorination magnesium addition, and therefore, the present embodiment realizes removal of impurities processing to the magnesium hydroxide filter cake first.It should remove and live together
The removal of impurities modes such as multistep washing filtering can be used in reason, it is preferred that difference of the present embodiment by magnesium hydroxide and impurity in water
Solubility handles it, and efficiently quick and good impurity removing effect, specific dedoping step are as follows for the removal of impurities processing procedure：
1）By magnesium hydroxide filter cake through being added in make-up tank, water is added into configured slot, is stirred, form the first thick liquid,
First thick liquid is filtered by sieves, filtered impurity is transferred to the inside of waste liquid cylinder, filtered first
The inside that thick liquid is introduced into heating kettle carries out next step operation, for the ease of the control of finishing operations, in first thick liquid
The mass fraction of water is 70%, and the temperature setting of the first thick liquid is 40 DEG C, and the temperature of the first thick liquid is maintained at 40 DEG C
The first thick liquid 20min of lower stirring,
2）The first thick liquid is heated to after 40 DEG C, and the temperature of the first thick liquid is maintained at 40 DEG C and stirs the first thick liquid
20min forms the second thick liquid；
The mode of heating is preferably steam heating, by the steam distributor being arranged in equipment, to realize to material in equipment
Heating, so that heating process is more economical and simple, it is also more convenient for the control of temperature.The material of first thick liquid
Liquid temperature remains 40 DEG C, if being not easy in the sodium chloride of crystal form and magnesium chloride since temperature is too low, in filter cake rapid molten
In solution to liquid phase, and if temperature is excessively high, not only waste thermal energy, and can operate and make troubles to the press filtration in later steps,
Operator's scald is easily caused, meanwhile, within this temperature range, the close maximum of solubility of sodium chloride, therefore, the present embodiment pair
The control of feed temperature can realize preferable impurity-eliminating effect, and conducive to the progress of subsequent step.
3）By the second thick liquid through filter press to form the second filter cake, which is above-mentioned magnesium hydroxide material.
Filter press is a kind of common solid-liquid separating equipment of chemical industry, is to utilize special filter medium, to filtering
Object applies certain pressure so that a kind of mechanical equipment that liquid dialysis comes out.Specifically, the filter press in the present embodiment is adopted
It is plate and frame filter press.
In order to further enhance the purity of magnesium hydroxide in the second filter cake, the present embodiment using the second filter cake of desalted water pair into
The third filter cake, to which third filter cake be made, is used as hydrogen by row washing to further decrease the content of chlorion in the second filter cake
Magnesia material can further promote the purity of the final product magnesium fluoride crystal obtained by the later stage.
Step S2：By magnesium hydroxide material with hydrofluoric acid solution according to the ratio between the amount of substance of magnesium hydroxide and hydrofluoric acid
For:1.35-1.45：1 mixing, according to reaction equation：Mg(HO)2+2HF= MgF2+2H2O occurs neutralization reaction and generates fluorination
Magnesium.
During neutralization reaction carries out, reaction temperature is controlled at 85 DEG C, and wherein reaction temperature is set as 85 DEG C, among the above
During occurring with reaction, if reaction temperature is too low, it is unfavorable for crystal and grows up, if conversely, reaction temperature is too high, is easy
So that unreacted HF is volatilized, increase cooling difficulty, therefore, the temperature that the present embodiment controls reaction solution is 85 DEG C, reaction time 2-3
Hour, the reaction later stage is slowly stirred or static processing, keeps crystal grain more perfect, neutralization reaction at the end, the reaction solution of formation
PH value at 4.5, wherein the pH value of reaction solution be 4.5.
Specifically, since the neutralization reaction in this step is exothermic reaction, the present embodiment is used is arranged folder on reaction kettle
Set, uses and allows cooling water by way of chuck to control the reaction temperature in this step.
Step S3：Magnesium fluoride crystalline solid is through separation process, drying process, and to which magnesium fluoride crystal be made, drying process is
Pneumatic conveying drying, the drying temperature in pneumatic conveying drying are 98 DEG C, and pressure is less than 0.01MPa, air-flow velocity 70km/h.
It is separated using centrifugal separation process to which magnesium fluoride is crystallized just body, is used in combination desalted water to crystalline solid into traveling
The washing of one step, the liquid after separation process can be discharged or be returned it in reactor, then participate in neutralization reaction, using industry
Water is to step 3）In the second Washing of Filter Cake, to form third filter cake and be used as the magnesium hydroxide material in step S2.
Just body realizes it by the way of pneumatic conveying drying drying process for isolated magnesium fluoride crystallization, pneumatic conveying drying
Mode is that the dispersion of scattered particulate solid material is suspended in velocity heated gas, a kind of method being dried under Geldart-D particle.
Embodiment three：The present embodiment provides a kind of preparation processes of magnesium fluoride, include the following steps：
Step S1：Using magnesium hydroxide filter cake as raw material, removal of impurities processing is carried out to magnesium hydroxide filter cake, to extract magnesium hydroxide
In order to improve the purity of the present embodiment final product, institute specifically is handled by above-mentioned removal of impurities for magnesium hydroxide material in filter cake
Cl in the magnesium hydroxide material of formation-Mass fraction require below 0.001%.
In the magnesium hydroxide filter cake, main matter is magnesium hydroxide, also contains partial oxidation sodium and a small amount of unreacted magnesium
Ion is formed by chlorination magnesium addition, and therefore, the present embodiment realizes removal of impurities processing to the magnesium hydroxide filter cake first.It should remove and live together
The removal of impurities modes such as multistep washing filtering can be used in reason, it is preferred that difference of the present embodiment by magnesium hydroxide and impurity in water
Solubility handles it, and efficiently quick and good impurity removing effect, specific dedoping step are as follows for the removal of impurities processing procedure：
1）Magnesium hydroxide filter cake is added in make-up tank, water is added into configured slot, is stirred, form the first thick liquid, it will
First thick liquid is filtered by sieves, and filtered impurity is transferred to the inside of waste liquid cylinder, and filtered first is thick
The inside that shape object is introduced into heating kettle carries out next step operation, for the ease of the control of finishing operations, water in first thick liquid
Mass fraction be 70%, the temperature setting of the first thick liquid is 47 DEG C, and the temperature of the first thick liquid is maintained at 47 DEG C
The first thick liquid 30min is stirred,
2）The first thick liquid is heated to after 47 DEG C, and the temperature of the first thick liquid is maintained at 47 DEG C and stirs the first thick liquid
30min forms the second thick liquid；
The mode of heating is preferably steam heating, by the steam distributor being arranged in equipment, to realize to material in equipment
Heating, so that heating process is more economical and simple, it is also more convenient for the control of temperature.The material of first thick liquid
Liquid temperature remains 47 DEG C, if being not easy in the sodium chloride of crystal form and magnesium chloride since temperature is too low, in filter cake rapid molten
In solution to liquid phase, and if temperature is excessively high, not only waste thermal energy, and can operate and make troubles to the press filtration in later steps,
Operator's scald is easily caused, meanwhile, within this temperature range, the close maximum of solubility of sodium chloride, therefore, the present embodiment pair
The control of feed temperature can realize preferable impurity-eliminating effect, and conducive to the progress of subsequent step.
3）By the second thick liquid through filter press to form the second filter cake, which is above-mentioned magnesium hydroxide material.
Filter press is a kind of common solid-liquid separating equipment of chemical industry, is to utilize special filter medium, to filtering
Object applies certain pressure so that a kind of mechanical equipment that liquid dialysis comes out.Specifically, the filter press in the present embodiment is adopted
It is plate and frame filter press.
In order to further enhance the purity of magnesium hydroxide in the second filter cake, the present embodiment using the second filter cake of desalted water pair into
The third filter cake, to which third filter cake be made, is used as hydrogen by row washing to further decrease the content of chlorion in the second filter cake
Magnesia material can further promote the purity of the final product magnesium fluoride crystal obtained by the later stage.
Step S2：By magnesium hydroxide material with hydrofluoric acid solution according to the ratio between the amount of substance of magnesium hydroxide and hydrofluoric acid
For:1.35-1.45：1 mixing, according to reaction equation：Mg(HO)2+2HF= MgF2+2H2O occurs neutralization reaction and generates fluorination
Magnesium.
During neutralization reaction carries out, reaction temperature is controlled at 88 DEG C, and wherein reaction temperature is set as 88 DEG C, among the above
During occurring with reaction, if reaction temperature is too low, it is unfavorable for crystal and grows up, if conversely, reaction temperature is too high, is easy
So that unreacted HF is volatilized, increase cooling difficulty, therefore, the temperature that the present embodiment controls reaction solution is 88 DEG C, reaction time 2-3
Hour, the reaction later stage is slowly stirred or static processing, keeps crystal grain more perfect, neutralization reaction at the end, the reaction solution of formation
PH value at 4.8, wherein the pH value of reaction solution be 4.8.
Specifically, since the neutralization reaction in this step is exothermic reaction, the present embodiment is used is arranged folder on reaction kettle
Set, uses and allows cooling water by way of chuck to control the reaction temperature in this step.
Step S3：Magnesium fluoride crystalline solid is through separation process, drying process, and to which magnesium fluoride crystal be made, drying process is
Pneumatic conveying drying, the drying temperature in pneumatic conveying drying are 98 DEG C, and pressure is less than 0.01MPa, air-flow velocity 70km/h.
It is separated using centrifugal separation process to which magnesium fluoride is crystallized just body, is used in combination desalted water to crystalline solid into traveling
The washing of one step, the liquid after separation process can be discharged or be returned it in reactor, then participate in neutralization reaction, using industry
Water is to step 3）In the second Washing of Filter Cake, to form third filter cake and be used as the magnesium hydroxide material in step S2.
Just body realizes it by the way of pneumatic conveying drying drying process for isolated magnesium fluoride crystallization, pneumatic conveying drying
Mode is that the dispersion of scattered particulate solid material is suspended in velocity heated gas, a kind of method being dried under Geldart-D particle.
Example IV：The present embodiment provides a kind of preparation processes of magnesium fluoride, include the following steps：
Step S1：Using magnesium hydroxide filter cake as raw material, removal of impurities processing is carried out to magnesium hydroxide filter cake, to extract magnesium hydroxide
In order to improve the purity of the present embodiment final product, institute specifically is handled by above-mentioned removal of impurities for magnesium hydroxide material in filter cake
Cl in the magnesium hydroxide material of formation-Mass fraction require below 0.001%.
In the magnesium hydroxide filter cake, main matter is magnesium hydroxide, also contains partial oxidation sodium and a small amount of unreacted magnesium
Ion is formed by chlorination magnesium addition, and therefore, the present embodiment realizes removal of impurities processing to the magnesium hydroxide filter cake first.It should remove and live together
The removal of impurities modes such as multistep washing filtering can be used in reason, it is preferred that difference of the present embodiment by magnesium hydroxide and impurity in water
Solubility handles it, and efficiently quick and good impurity removing effect, specific dedoping step are as follows for the removal of impurities processing procedure：
1）Magnesium hydroxide filter cake is added in make-up tank, water is added into configured slot, is stirred, form the first thick liquid, it will
First thick liquid is filtered by sieves, and filtered impurity is transferred to the inside of waste liquid cylinder, and filtered first is thick
The inside that shape object is introduced into heating kettle carries out next step operation, for the ease of the control of finishing operations, water in first thick liquid
Mass fraction be 70%, the temperature setting of the first thick liquid is 50 DEG C, and the temperature of the first thick liquid is maintained at 50 DEG C
The first thick liquid 40min is stirred,
2）The first thick liquid is heated to after 50 DEG C, and the temperature of the first thick liquid is maintained at 50 DEG C and stirs the first thick liquid
40min forms the second thick liquid；
The mode of heating is preferably steam heating, by the steam distributor being arranged in equipment, to realize to material in equipment
Heating, so that heating process is more economical and simple, it is also more convenient for the control of temperature.The material of first thick liquid
Liquid temperature remains 50 DEG C, if being not easy in the sodium chloride of crystal form and magnesium chloride since temperature is too low, in filter cake rapid molten
In solution to liquid phase, and if temperature is excessively high, not only waste thermal energy, and can operate and make troubles to the press filtration in later steps,
Operator's scald is easily caused, meanwhile, within this temperature range, the close maximum of solubility of sodium chloride, therefore, the present embodiment pair
The control of feed temperature can realize preferable impurity-eliminating effect, and conducive to the progress of subsequent step.
3）By the second thick liquid through filter press to form the second filter cake, which is above-mentioned magnesium hydroxide material.
Filter press is a kind of common solid-liquid separating equipment of chemical industry, is to utilize special filter medium, to filtering
Object applies certain pressure so that a kind of mechanical equipment that liquid dialysis comes out.Specifically, the filter press in the present embodiment is adopted
It is plate and frame filter press.
In order to further enhance the purity of magnesium hydroxide in the second filter cake, the present embodiment using the second filter cake of desalted water pair into
The third filter cake, to which third filter cake be made, is used as hydrogen by row washing to further decrease the content of chlorion in the second filter cake
Magnesia material can further promote the purity of the final product magnesium fluoride crystal obtained by the later stage.
Step S2：By magnesium hydroxide material with hydrofluoric acid solution according to the ratio between the amount of substance of magnesium hydroxide and hydrofluoric acid
For:1.35-1.45：1 mixing, according to reaction equation：Mg(HO)2+2HF= MgF2+2H2O occurs neutralization reaction and generates fluorination
Magnesium.
During neutralization reaction carries out, reaction temperature is controlled at 88 DEG C, and wherein reaction temperature is set as 88 DEG C, among the above
During occurring with reaction, if reaction temperature is too low, it is unfavorable for crystal and grows up, if conversely, reaction temperature is too high, is easy
So that unreacted HF is volatilized, increase cooling difficulty, therefore, the temperature that the present embodiment controls reaction solution is 90 DEG C, reaction time 2-3
Hour, the reaction later stage is slowly stirred or static processing, keeps crystal grain more perfect, neutralization reaction at the end, the reaction solution of formation
PH value at 5.0, wherein the pH value of reaction solution be 5.0.
Specifically, since the neutralization reaction in this step is exothermic reaction, the present embodiment is used is arranged folder on reaction kettle
Set, uses and allows cooling water by way of chuck to control the reaction temperature in this step.
Step S3：Magnesium fluoride crystalline solid is through separation process, drying process, and to which magnesium fluoride crystal be made, drying process is
Pneumatic conveying drying, the drying temperature in pneumatic conveying drying are 98 DEG C, and pressure is less than 0.01MPa, air-flow velocity 70km/h.
It is separated using centrifugal separation process to which magnesium fluoride is crystallized just body, is used in combination desalted water to crystalline solid into traveling
The washing of one step, the liquid after separation process can be discharged or be returned it in reactor, then participate in neutralization reaction, using industry
Water is to step 3）In the second Washing of Filter Cake, to form third filter cake and be used as the magnesium hydroxide material in step S2.
For this step during pneumatic conveying drying, drying temperature control is 95 ~ 100 DEG C, and pressure is less than 0.01MPa, gas
Stream flow velocity is 70km/h, and suitable drying temperature can improve the discharging purity of magnesium fluoride crystal.
The preparation-obtained magnesium fluoride crystal of technique in through this embodiment, appearance are in colourless tetragonal crystal or powder
The mass fraction at end, magnesium fluoride is 99.0 ~ 99.5%, chloride≤0.001%, lead（Pb）≤ 0.0002, % arsenic（As）%≤
0.0003, heavy metal mass fraction（In terms of Pb）Less than 0.001%.
And the preparation process of magnesium fluoride that the present embodiment is provided carries the hydroxide discarded in lithium technique using salt lake bittern
Magnesium filter cake has been effectively saved the cost of raw material, specifically as raw material relative to the preparation process of traditional magnesium fluoride crystal
Analytic process is as follows：
The calculating of raw material is on the basis of producing 1t magnesium fluorides in following two technique.
1. the calculating of raw material in the present embodiment technique
Reaction equation is as follows：Mg(HO)2+2HF= MgF2+2H2O
58 40 62
X Y 1
It is computed, X=58/62=Y=40/62 0.935t=0.645t
Raw material hydrofluoric acid solution used in this technique is the industrial hydrofluoric acid that mass percent concentration is 20 ~ 30%, if pressing
30% calculates, then the acid amount consumed is：0.645/0.3=2.15t.
Magnesium hydroxide raw material used in this technique is that salt lake carries the magnesium hydroxide filter cake discarded in lithium technique, it is general its
The content of solid magnesium hydroxide is 40 ~ 60%（The content of butt magnesium hydroxide is generally 85 ~ 90%）If being calculated by 85%, needed for
The waste quality containing magnesium hydroxide be：0.935/0.85=1.1t.
2. the calculating of raw material in traditional handicraft
Reaction equation is as follows：
MgCO3+2HF— MgF2+CO2 +H2O
84 40 62
X Y 1
According to can be calculated：
X=84/62=1.35t Y=40/62=0.645t
Raw material hydrofluoric acid solution used in this technique is the industrial hydrofluoric acid that mass percent concentration is 20~30%, if pressing
30% calculates, then the acid amount consumed is：0.645/0.3=2.15
This technique compares with traditional handicraft, and the consumption of hydrofluoric acid is 2.15, and the magnesium that the technique of the present embodiment is utilized is former
Material is waste, therefore is not counted in the consumption of raw material, and traditional handicraft need to consume the magnesium carbonate of 1.35t, and the magnesium carbonate
That outsourcing or calcining generate, therefore, the raw material of the significantly high technique in this present embodiment of the cost of raw material of traditional handicraft at
This.
Therefore, the preparation process of magnesium fluoride provided in this embodiment can not only produce magnesium fluoride crystal best in quality,
Suitable for industrial application, and the preparation process of the magnesium fluoride of the present embodiment production carries giving up in lithium production process using salt lake bittern
Gurry magnesium hydroxide filter cake solves the problems, such as the burial of the waste magnesium hydroxide filter cake, and effectively saves magnesium fluoride crystal
Manufacturing cost, meanwhile, the preparation process for the magnesium fluoride that the present embodiment is provided, process is simple, and energy consumption is few, meets green circulatory
Economic theory.
Claims (9)
1. a kind of preparation process of magnesium fluoride, it is characterised in that：Include the following steps：
Step S1：Using magnesium hydroxide filter cake as raw material, removal of impurities processing is carried out to the magnesium hydroxide filter cake, it is described to extract
Magnesium hydroxide material in magnesium hydroxide filter cake, Cl in the magnesium hydroxide material-Mass fraction be 0.001% or less.
Step S2：It is according to the ratio between the amount of substance of magnesium hydroxide and hydrofluoric acid with hydrofluoric acid solution by the magnesium hydroxide material
1.35-1.45：1 mixing, according to reaction equation：Mg(HO)2+2HF= MgF2+2H2O occurs neutralization reaction and forms magnesium fluoride.
Step S3：Just magnesium fluoride crystal is made through separating, washing process, drying process in body for the magnesium fluoride crystallization.
2. the preparation process of magnesium fluoride according to claim 1, it is characterised in that：Magnesium hydroxide filter in the step S1
The source of cake is to carry in lithium technique being formed from salt lake bittern, and the removal of impurities treatment process in step S1 includes the following steps：
1）The magnesium hydroxide filter cake is added in make-up tank, water is added into configured slot, is stirred, form the first thick shape
Object；
2）First thick liquid is heated to after 40 ~ 50 DEG C, and the temperature of first thick liquid is maintained at 40 ~ 50 DEG C and is stirred
First thick liquid, 20 ~ 40min is mixed, the second thick liquid is formed；
3）By second thick liquid through filter press to form the second filter cake.
3. the preparation process of magnesium fluoride according to claim 2, it is characterised in that：The temperature setting of first thick liquid
It is 47 DEG C, and the temperature of the first thick liquid is maintained at 47 DEG C and stirs the first thick liquid 30min.
4. the preparation process of magnesium fluoride according to claim 2, it is characterised in that：Using desalted water to step 3）In institute
The second Washing of Filter Cake is stated, to form third filter cake and be used as the magnesium hydroxide material in step S2.
5. the preparation process of magnesium fluoride according to claim 1, it is characterised in that：Step S2 is carried out in the neutralization reaction
During, reaction temperature controls between 85 ~ 90 DEG C.
6. the preparation process of magnesium fluoride according to claim 5, it is characterised in that：The reaction temperature is arranged at 88 DEG C.
7. the preparation process of magnesium fluoride according to claim 1, it is characterised in that：Neutralization reaction described in step S2 is being tied
Shu Shi, the pH value of the reaction solution of formation is between 4.5 ~ 5.
8. the preparation process of magnesium fluoride according to claim 7, it is characterised in that：The pH value of the reaction solution of the formation is
4.8。
9. the preparation process of magnesium fluoride according to claim 1, it is characterised in that：The drying process in step S3 is
Pneumatic conveying drying, the drying temperature in the pneumatic conveying drying are 98 DEG C, and pressure is less than 0.01MPa, air-flow velocity 70km/h.
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101376514A (en) * | 2007-08-30 | 2009-03-04 | 多氟多化工股份有限公司 | Preparation of magnesium fluoride |
| CN102674410A (en) * | 2011-03-09 | 2012-09-19 | 多氟多化工股份有限公司 | Production method for high-purity magnesium fluoride crystal |
| CN103214012A (en) * | 2013-04-24 | 2013-07-24 | 湖南有色氟化学科技发展有限公司 | Method for preparing magnesium fluoride |
| CN106348322A (en) * | 2016-10-11 | 2017-01-25 | 张旭 | Method for preparing high-purity magnesium fluoride by using magnesite |
| CN107352562A (en) * | 2017-08-10 | 2017-11-17 | 青海盐湖工业股份有限公司 | A kind of preparation technology of magnesium fluoride |
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2018
- 2018-03-22 CN CN201810239313.0A patent/CN108285161A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101376514A (en) * | 2007-08-30 | 2009-03-04 | 多氟多化工股份有限公司 | Preparation of magnesium fluoride |
| CN102674410A (en) * | 2011-03-09 | 2012-09-19 | 多氟多化工股份有限公司 | Production method for high-purity magnesium fluoride crystal |
| CN103214012A (en) * | 2013-04-24 | 2013-07-24 | 湖南有色氟化学科技发展有限公司 | Method for preparing magnesium fluoride |
| CN106348322A (en) * | 2016-10-11 | 2017-01-25 | 张旭 | Method for preparing high-purity magnesium fluoride by using magnesite |
| CN107352562A (en) * | 2017-08-10 | 2017-11-17 | 青海盐湖工业股份有限公司 | A kind of preparation technology of magnesium fluoride |
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Application publication date: 20180717 |