CN108190924A - A kind of preparation method for reducing magnesium hydroxide chlorinity - Google Patents
A kind of preparation method for reducing magnesium hydroxide chlorinity Download PDFInfo
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- CN108190924A CN108190924A CN201810143616.2A CN201810143616A CN108190924A CN 108190924 A CN108190924 A CN 108190924A CN 201810143616 A CN201810143616 A CN 201810143616A CN 108190924 A CN108190924 A CN 108190924A
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- magnesium hydroxide
- magnesium
- dechlorination
- chlorinity
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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
- C01F5/14—Magnesium hydroxide
- C01F5/145—Purification
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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
- C01F5/14—Magnesium hydroxide
- C01F5/20—Magnesium hydroxide by precipitation from solutions of magnesium salts with ammonia
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- 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
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Abstract
The invention belongs to magnesium hydroxide preparation field, the method for being specifically put forward for the first time the chlorine in cleaning magnesium hydroxide；In the present invention, the pending magnesium hydroxide containing chlorine impurity is carried out to the agitator treating of single-stage；Or the multi-stage countercurrent agitator treating through chlorine removal system, obtain dechlorination magnesium hydroxide；The present invention originally proposes a kind of using adverse current stirring mode of washing.The chlorinity of magnesium hydroxide can be down to 0.2% and less by the method for the present invention by more than 0.8%.
Description
Technical field
The invention belongs to magnesium hydroxide preparation fields, and in particular to a kind of preparation process of low chlorine root high purity magnesium hydroxide
Background technology
China's salt lake resources are also very abundant, in have 1km2Above salt lake area has 731, these gross areas have added
To have reached 23784km2Resourceful in belong to Chaidamu Basin, Qinghai Province, sylvite reserves are about in this area salt lake
40.4 hundred million tons, magnesium salts reserves are about 48.15 hundred million tons, wherein 65.3% magnesium salts is magnesium chloride, 34.7% is magnesium sulfate.External
Salt lake resources mainly have near the Sears salt lake and Great Salt lake, the Atacama salt lake of Chile, Israel and Jordan in the U.S.
Dead Sea etc..With being constantly progressive for science and technology, foreign countries have been no longer satisfied with exploit resources of salt lakes to produce single chemical products,
But it is comprehensively utilized towards diversification.
Qinghai Chaerhan salt lakes are the important potash fertilizer production bases in China, and a large amount of enrichments are generated in potassium fertilizer production process
The old halogen of magnesium chloride utilizes local advantageous weather conditions, it is easy to evaporated by salt pan, condensing crystallizing obtain it is inexpensive
Bischofite (MgCl of fine quality2.6H2O) solid mineral is a kind of highly important salt lake magnesium resource.
China salt lake magnesium resource very abundant, the production development of salt lake magnesium resource is mainly Salt Lake Potash by-product water chlorine magnesium
The production development of stone, at present still in the starting stage, there are no the bischofite resource synthetic development profits for setting up complete set
Use industrial system.
The exploitation of China salt lake magnesium resource is mainly the exploitation of Cha Er Han Salt Lake bischofite resource, it is produced in potash fertilizer
That discharges in the process is enriched the old halogen of magnesium salts, using local advantageous natural climate condition, is concentrated by evaporation by salt pan
A kind of obtained secondary magnesium resource solid mineral is crystallized, has the characteristics that grade is high, impurity content is low, stock number is big.Qaidam
Area has the resources such as abundant water power, oil, and sufficient guarantee is provided for magnesium salts production plant.In addition in building at present
" West-east Gas engineering provides most strong support for the constantly upgrading of magnesium secondary industry.National development of the West Regions correlation state simultaneously
The positive support of family's policy, soil is cheap, and market more specification, system is more complete, therefore the exploitation of salt lake magnesium resource has
Significantly advantage.
Magnesium hydroxide, white, character is clear crystal, belongs to hexagonal crystal system, insipidness, and nontoxic and corrosivity.It is high-purity
Magnesium hydroxide refers to the product that magnesium hydroxide content is more than 99%, and decomposition temperature is high, absorbs that heat is big, is a kind of important inorganic
Chemical materials is widely used, mainly in fire retardant, flue gas desulfurization, wastewater treatment etc..
High purity magnesium hydroxide is that " magnesia brick " factory carries out magnesite with hydrochloric acid rich choosing, and its granularity is ground into earliest
0.5mm is handled by removal of impurities hereinafter, be re-dissolved in the hydrochloric acid of a concentration of 12.5-20%, and precipitation obtains high purity magnesium hydroxide.
In the world, the U.S., the earliest acquisition of Japan and Britain prepare the mature technology of highly-purity magnesite.Later, Italian, Mexico is moved
The states such as prestige and Greece prepare high purity magnesium hydroxide in succession.
West Europe area is mostly seawater method, and sinking speed therein and detersive efficiency are focus.Research shows that dolomite
Ash makees precipitating reagent and magnesium hydroxide optimum condition is produced in seawater reaction, is using A-130 flocculants, sinking speed is greatly
By force, device capability also accordingly improves.
The production scale of Chinese high purity magnesium hydroxide is small, ageing equipment, it is impossible to meet the needs of market.High purity magnesium in recent years
Product salt scientific achievement is constantly gushed out, and most all puts into market, even if but these also domestic markets far from enough demand,
Outlet is even more fewer and fewer, and since output is few, magnesium salts business economic does not improve yet.So production functionalization magnesium salts product is
The only way which must be passed of magnesium salts development.
On the whole, still in the primary stage, product is single, and added value is inadequate, functional not strong for Chinese magnesium salts production.Example
Such as fire retardant magnesium hydroxide, pharmaceutical magnesium hydroxide etc., domestic demand once it is big can only import.This situation causes the country already
Numerous universities and colleges, Research Center and magnesium salts enterprise are note that be now to do is exactly positive input human and material resources exploitation new technology, new work
Skill meets the needs of domestic and external, improves product specification, occupying inter-national market.
In the prior art, the chlorinity of magnesium hydroxide is higher, but the chlorinity of magnesium hydroxide is not paid close attention in this field.
Invention content
The present invention focuses on the technical issues of chlorinity of magnesium hydroxide for the first time, provides a kind of reduction magnesium hydroxide chlorinity
Preparation method, pass through the present invention originally multi-stage countercurrent agitator treating, it is intended to which the chlorine for the magnesium hydroxide being substantially reduced contains
Amount.
Pending magnesium hydroxide containing chlorine impurity is carried out single-stage by a kind of preparation method for reducing magnesium hydroxide chlorinity
Agitator treating；Or the multi-stage countercurrent agitator treating through chlorine removal system, obtain dechlorination magnesium hydroxide；
The chlorine removal system includes multistage dechlorination unit；Each dechlorination unit is both provided with the entrance of magnesium hydroxide and goes out
Mouth, the outlet of cleaning solution and entrance；Each dechlorination unit is serially connected by the outlet and entrance of magnesium hydroxide, wherein, the
Inlet port of the magnesium hydroxide entrance of level-one dechlorination unit for pending magnesium hydroxide, the hydroxide of afterbody dechlorination unit
Extraction mouth of the magnesium outlet for the magnesium hydroxide after dechlorination；
The rinse liquid outlet of the dechlorination unit of the first order be cleaning after cleaning solution extraction mouth, the dechlorination list of afterbody
The clear liquid liquid entrance of member is the inlet port of clear water；The outlet of the cleaning solution of other dechlorination units at different levels is upper with being respectively in series
The filter washing water inlet connection of level-one dechlorination unit；
Magnesium hydroxide enters the chlorine removal system by the magnesium hydroxide entrance of first order dechlorination unit, and clear water is by last
The feed liquid port of grade enters chlorine removal system；Magnesium hydroxide from the first order dechlorinate unit to afterbody dechlorinate unit motion；Cleaning
Liquid agitator treating, stirring in each dechlorination unit from afterbody to first order dechlorination unit motion, magnesium hydroxide and clear liquid liquid
Magnesium hydroxide after washing exports extraction by the magnesium hydroxide of afterbody dechlorination unit, and cleaning solution is by first order dechlorination unit
Rinse liquid outlet produces.
First, present invention firstly provides the methods of the chlorinity in cleaning magnesium hydroxide.In addition, the present inventor is originally
A kind of preparation method for the chlorinity for reducing magnesium hydroxide is provided, i.e., by chlorine removal system of the present invention, to described
Magnesium hydroxide carry out multi-stage countercurrent agitator treating, chlorinity that can be in efficient removal magnesium hydroxide.
Processing system of the present invention respectively dechlorinates in unit, and the outlet of the magnesium hydroxide is preferably provided at dechlorination
The lower part of unit；The entrance of the magnesium hydroxide is preferably provided at the top of dechlorination unit.The entrance of the cleaning solution and
Outlet is preferably provided at the top of dechlorination unit, and the outlet of the cleaning solution and entrance are arranged on the phase on dechlorination unit top
To position.
Each dechlorination unit of the present invention is additionally provided with agitating device, magnesium hydroxide is transferred to next stage dechlorination list
The transfer device of member and the grass-hopper for shifting cleaning solution to upper level dechlorination unit.
Pending magnesium hydroxide enters chlorine removal system by first order dechlorination unit, and clear water is entered by the cleaning solution of afterbody
Mouth enters system；Magnesium hydroxide first shifts the cleaning solution to come and is stirred in the first order dechlorinates unit with second level dechlorination unit
Washing is mixed, the magnesium hydroxide after first order agitator treating then continuously or is discontinuously transferred to second level dechlorination unit, with
The cleaning solution that third level transfer comes is followed by stirring and washing, and multi-stage countercurrent stirring is carried out so in the processing system and is washed
It washs；Until the outlet by the magnesium hydroxide of afterbody produces.
The present inventor is the study found that the cooperation present invention is originally used described in chlorine removal system of the present invention progress
Multi-stage countercurrent agitator treating controls suitable agitator treating parameter, can further promote dechlorination effect.
The study found that grain size (bulk density), the speed of agitator of washing process, the liquid to pending magnesium hydroxide are solid
Regulated and controled than parameters such as, wash temperatures, can further promote dechlorination effect.
Preferably, the bulk density 0.8-2.0g/ml of the pending magnesium hydroxide；Further preferably 1.2-
1.5g/ml.The study found that control can further promote dechlorination effect, additionally aid into one in the range of suitable bulk density
Step is conducive to multi-stage countercurrent agitator treating of the present invention, helps to promote preparation effect.
In actual production, can the pending magnesium hydroxide be ground processing in advance, can by milling time,
Control the obtained bulk density of pending magnesium hydroxide in preferred range.Preferably, the pending hydrogen
Magnesia is ground processing in advance before washing, and milling time is 5~20min, further preferably 5~10min.
During multi-stage countercurrent agitator treating, in each dechlorination unit, by the upper level magnesium hydroxide that comes of transfer with by
The cleaning solution that next stage transfer comes is followed by stirring and washing；Control suitable solid-to-liquid ratio and speed of agitator and in each dechlorination unit
Residence time can cooperate with the removal washing effect for promoting chlorine.
Preferably, during agitator treating, the solvent and solute weight ratio of magnesium hydroxide and cleaning solution is 1~5: 1.Liquid portion
Large percentage when, can help to be promoted dechlorination effect, but higher liquid accounting, it is low to prepare effect, and the rate of filtration is
Decline.
Further preferably, during agitator treating, the solvent and solute weight ratio ratio of magnesium hydroxide and cleaning solution is 2~4: 1.At this
Under preferred liquid-solid ratio, dechlorination effect is good, and preparation efficiency is high.
Preferably, the temperature of agitator treating process is 50~90 DEG C.The study found that when range temperature is higher, it can be into one
It walks and promotes dechlorination effect, the dechlorination effect under relatively low and higher wash temperature is declined.
Further preferably, the temperature of agitator treating process is 60~80 DEG C.At the preferred temperature, dechlorination effect reason
Think, and preparation efficiency is high, the rate of filtration is fast, conducive to industrial mass production.
Preferably, during agitator treating, speed of agitator is not less than 50r/min.When stirring very fast, the removal effect of chlorine
Preferably, but stirring is too fast, is unfavorable for industrial production implementation, and the rate of filtration is slow.
Further preferably, during agitator treating, speed of agitator is 50~250r/min；Most preferably 100~250r/
min.Under the preferred speed of agitator, production efficiency is high, and the effect that dechlorinates is more preferable.
Preferably, under the agitator treating temperature, solid-to-liquid ratio, speed of agitator, the preferred agitator treating time is big
In 10min.Agitator treating time lengthening, dechlorination effect are further promoted, but the rate of filtration is declined.
Further preferably, the agitator treating time be greater than or equal to 10min, be 10~60min, further preferably 30~
60min.Under the preferred agitator treating time, dechlorination effect, production effect are more preferable.
The method of the present invention is applicable to the processing of the magnesium hydroxide of arbitrary C 1 content；Being preferably applied to chlorine impurity content is
The processing of the magnesium hydroxide of 0.6-0.9%.
In the present invention, the cleaning solution of single-stage washing process is clear water.
Under the parameter washed in the single-stage, the chlorinity of magnesium hydroxide can be down to 0.3% or so, but clean effect
Fruit is unstable.In the present invention, using currently preferred multi-stage countercurrent cleaning method, the cleaning performance of chlorine is more preferable, and can be real
Existing serialization cleaning, comparatively, the cleaning fluid volume used more saves.
Preferably, in the chlorine removal system, the series connection series of the dechlorination unit is 2~10 grades；Preferably 3~
6 grades.Under the multistage wash conditions, under the magnesium hydroxide of any chlorinity, chlorinity can be obtained 0.2% or so
It is and following.
Pending magnesium hydroxide of the present invention can be the existing product of outsourcing or be synthesized using the prior art
Product.
In the present invention, the pending magnesium hydroxide is preferably obtained using ammonia process.
Preferably, the preparation process of the pending magnesium hydroxide is：Magnesium chloride solution and ammonium hydroxide are added dropwise together
It into the ammonium hydroxide added with magnesium hydroxide crystal seed-chloride buffer system, is stirred to react, pending magnesium hydroxide is made.
The present inventor is the study found that the parameter of the preparation process to pending magnesium hydroxide, such as magnesium chloride solution, ammonia
The concentration of water, dropwise addition mode, dropwise addition ratio, crystal seed and the dosage of crystal seed, the speed of agitator being stirred to react, reaction temperature etc.
Parameter is rationally controlled, and is made with the pending magnesium hydroxide for being more conducive to multi-stage countercurrent agitator treating of the present invention, cooperation is originally
The invention multi-stage countercurrent agitator treating can further reduce dechlorination effect, and promote strainability, promoted and prepare effect,
It is made to be more suitable for industry amplification metaplasia production.
The magnesium chloride solution can be the solution obtained after conventional impurity removal process removal of impurities after bischofite dissolves,
Can be the solution obtained in water using analysis level magnesium chloride solution.
Preferably, the molar concentration of the magnesium chloride solution is 1~4moL/L；Further preferably 2~3moL/L.
Preferably, a concentration of 10~13.3mol/L of ammonium hydroxide.
Preferably, the ratio (molar ratio) that adds of magnesium chloride solution and ammonium hydroxide is 1: 2-1: 8；Further preferably 1: 2-
1∶5；Still more preferably it is 1: 2.2~2.8.
In the present invention, the magnesium chloride solution, ammonium hydroxide are added dropwise in reaction system simultaneously, by controlling speed of agitator
And reaction temperature, coordinate multi-stage countercurrent agitator treating of the present invention, can further promote dechlorination effect.
The buffer solution of pH=9 that ammonium hydroxide of the present invention-chloride buffer system is matched for ammonium hydroxide and ammonium chloride.
Preferably, the magnesium hydroxide seed load is the 10~40% of product.
The study found that the addition of crystal seed can influence the conversion ratio of product, influence the rate of filtration and bulk density of product.
Preferably, the magnesium hydroxide seed load is 20~30%.Under the preferred seed load, product
High conversion rate, filter efficiency it is high, obtained product coordinates agitator treating method of the present invention, can further promote dechlorination
Effect.
Preferably, the speed of agitator being stirred to react is not less than 50r/min；Further preferred 50~150r/min.Stirring
Speed increases, strainability enhancing, as long as but stir to disperse solution, in increase mixing speed, strainability just becomes
Change less, illustrate that mixing speed plays the dispersion for making hydrogen chloride magnesium solution and reduces instantaneous saturation degree, the granularity for generating precipitation increases
Greatly.
Further preferably, the speed of agitator being stirred to react is 100~150r/min.
Preferably, the temperature for being stirred to react process is 40~80 DEG C.
Preferably, be stirred to react the time as 10~40min, during 30mins；Grain is maximum.
The method of the reduction chlorinity of the present invention, especially suitable for the dechlorination using magnesium hydroxide made from chlorine magnesium ammonia process.
During magnesium hydroxide made from processing chlorine magnesium ammonia process, the technique of multi-stage countercurrent cleaning using the present invention is compared to single-stage
Washing, advantage becomes apparent from, for example, can be by chlorinity stabilization 0.2% or so, dechlorination effect is more preferable, and can well remove
Ammonia in magnesium hydroxide.
Advantageous effect
1st, the present invention can help to be obviously improved the removing effect of chlorine originally using multi-stage countercurrent agitator treating mode
Fruit.
2nd, the present invention is using agitator treating mode, by studying Aging Temperature, digestion time, liquid-solid ratio, mixing speed etc.
Factor, and the technologies such as creative invention grinding, the ageing of multistage counter current agitator treating reduce chloride content in product, to determine drop
The optimum process condition of low chlorine root.
3rd, pending magnesium hydroxide of the present invention can be raw material by bischofite, first dissolved, filtered and only with pure water
Eliminate it is miscellaneous obtain the brine of high concentration, then using ammonium hydroxide as precipitating reagent, using brine-ammonia precipitation preparing magnesium hydroxide, research
The factors such as reaction temperature, reaction time, mixing speed and feed way and charging rate stir magnesium hydroxide granularity and filtering
The influence of scourability,
4th, using magnesium hydroxide made from the method for the present invention cleaning chlorine magnesium ammonia process, multi-stage countercurrent washing, which removes, can make dechlorination effect
Control 0.2% and hereinafter, can also significantly remove ammonia, the granularity of the magnesium hydroxide maintained.
Description of the drawings：
Fig. 1 is the preparation flow schematic diagram of magnesium hydroxide；
Fig. 2 is Multi-stage stirring adverse current agitator treating schematic diagram.
Specific embodiment
Magnesite light burnt powder technical grade Gansu Jin Mao Sociedad De Desarrollo Minero Limitada "Sodemi Ltda" provides.
Magnesium chloride solution of the present invention can be used following methods and obtain：The bischofite of 500g or so is weighed, is added in
100ml distills water dissolution, stands overnight, and is filtered by vacuum, removes insoluble matter, insoluble matter is put into and dissolves beaker next time
In, in order to avoid causing to waste, the saturation magnesium chloride solution being configured is put into spare in large beaker.Measuring density of magnesium chloride is
4.81mol/l。
It tests obtained saturation magnesium chloride solution and is heated to 120 DEG C, be put into after slowly cooling down at room temperature and be recrystallized to give water
Chloromagnesite, the content of element in the saturation magnesium chloride that the two is worked it out, as a result such as table 1：
The comparison of 1 primary crystallization of table and element in saturation magnesium chloride after recrystalizing solvent
As shown in Table 1, the bischofite impurity element being recrystallized to give is significantly fewer than primary crystallization, and purity reaches
More than 99%.So in order to reduce the impurity in raw material bischofite, the bischofite after selection recrystallizes does my subsequent experimental
Raw material.
This experiment is that magnesium chloride solution and ammonium hydroxide are added drop-wise to the ammonium hydroxide added with magnesium hydroxide crystal seed-chloride buffer body together
In system, certain reaction temperature and rate of addition are controlled, magnesium hydroxide is made by reacting.It finally washs, filter, be dried to obtain
Product.
In the present invention, the parameter of the preparation process of Examples 1 to 7 screening magnesium hydroxide：In Examples 1 to 7, except special sound
Bright outer, the molar concentration of the magnesium chloride of use is 4.81mol/1 obtained above；Ammonia concn 13.33mol/1.
Embodiment 1
Respectively by the MgCl of various concentration2Solution carries out single factor experiment, while adds in MgCl2And ammonia spirit
(13.33mol/l), magnesium chloride and ammonium hydroxide reaction rate of addition are all 10ml/min, stir speed (S.S.) 150r/min, reaction temperature
80 DEG C, to continue mixing time after adding be 30min to material, magnesium hydroxide obtained by the reaction, as a result such as table 2：
2 brine magnesium ion concentration of table influences product filtration rate
From the point of view of magnesium conversion ratio, Mg Cl2For concentration in 3mol/l, magnesium conversion ratio is higher.In low concentration, increase Mg2+It is dense
Degree conversion ratio is obviously improved, and the rate of filtration slightly improves, and after 3mol/l, conversion ratio variation slows down, the rate of filtration and accumulation
Variable density is apparent, this is because Mg2+Concentration increases, and glue occurs in solution, and stirring action is weakened, and magnesium ion is spread by shadow
It rings.Therefore brine magnesium ion concentration selects 3mol/l.
Embodiment 2
In experimentation, while add in MgCl2And ammonia spirit, magnesium chloride and ammonium hydroxide reaction rate of addition are all 10ml/
It is 30min that min, stir speed (S.S.) 150r/min, 80 DEG C of reaction temperature, material continue mixing time after adding, obtained by the reaction
Magnesium hydroxide, MgCl2It is respectively 1: 2.2,1: 2.4,1: 2.6,1: 2.8 with ammonia molar ratio of material, other conditions keep the same.
To result such as table 3：
3 material ratio of table influences product filtration rate
From experimental data as can be seen that ammonia vol increases, be conducive to crystal and grow up, the rate of filtration and bulk density significantly become
Change, but material ratio be more than 1: 2.6 after, the rate of filtration slowly reduces, this is because reaction in the concentration of free ammonia it is big, make magnesium hydroxide
Instantaneous degree of supersaturation increase, be conducive to nucleus formation be but unfavorable for growing.So experimental selection ammonia material ratio is 1: 2.6.
Embodiment 3
Add in MgCl2 (3mol/l) and ammonia spirit (MgCl simultaneously2It is respectively 1 with ammonia molar ratio of material: 2.6), and chlorination
Magnesium and ammonium hydroxide reaction rate of addition are all 10ml/min, stir speed (S.S.) 150r/min, 80 DEG C of reaction temperature, material add it is subsequent
Continuous mixing time is 30min, adds in the magnesium hydroxide of product reacting dose 10%-40% as crystal, hydroxide obtained by the reaction
Magnesium, as a result such as table 4：
4 Seed charge of table influences product filtration rate
When crystal seed amount is 10%, filter cake is slower in the hardened rate of filtration, and more than 20%, the rate of filtration is slowly increased, and
30% conversion ratio maximum is added in, so selecting the magnesium hydroxide for adding in reacting dose 30% appropriate as crystal seed.
Embodiment 4
Add in MgCl simultaneously2(3mol/1) and ammonia spirit, magnesium chloride and ammonium hydroxide reaction rate of addition are all 10ml/min
(MgCl2Be respectively 1 with ammonia molar ratio of material: 2.6), stir speed (S.S.) be 50~150r/min, 80 DEG C of reaction temperature, material add
It is 30min to continue mixing time afterwards, adds in the magnesium hydroxide of product reacting dose 30% as crystal, hydroxide obtained by the reaction
Magnesium, the result such as table 5 obtained under different speeds of agitator：
5 mixing speed of table influences product filtration rate
From table 5, it can be seen that other conditions are constant, mixing speed increase, strainability enhancing, as long as but stirring and
Disperse solution, in increase mixing speed, strainability just changes less, and illustrating that mixing speed plays makes hydrogen chloride magnesium solution
Disperse and reduce instantaneous saturation degree, generate the granularity increase of precipitation.So selection mixing speed 150r/min.
Embodiment 5
Add in MgCl simultaneously2With ammonia spirit (MgCl2It is respectively 1 with ammonia molar ratio of material: 2.6), magnesium chloride and ammonium hydroxide are anti-
It is all 10ml/min to answer rate of addition, the magnesium hydroxide of stir speed (S.S.) 150r/min, addition product reacting dose 30% is as brilliant
Body, material continue mixing time as 30min at 40~80 DEG C, under 150r/min after adding, magnesium hydroxide obtained by the reaction,
The results are shown in Table 6 under condition of different temperatures：
6 reaction temperature of table influences product filtration rate
As shown in Table 6, temperature is high, and the rate of filtration is accelerated, but temperature is excessively high, and ammonium hydroxide utilization rate reduces, there-necked flask internal pressure
Power increase is also easy to cause experiment accident, so when temperature reaches 80 DEG C, temperature should not add again.
Embodiment 6
By MgCl2Solution (concentration 3moL/L) carries out single factor experiment, while adds in MgCl2With ammonia spirit ((MgCl2With
Ammonia molar ratio of material is respectively 1: 2.6)), stir speed (S.S.) 150r/min, 80 DEG C of reaction temperature, material continue to stir after adding
Time is 30min, and magnesium hydroxide obtained by the reaction, other conditions are constant, changes reaction rate of addition, as a result such as table 7.
7 ammonium hydroxide of table, magnesium chloride rate of addition influence product filtration rate
According to table 7, can analyze：When magnesium chloride dropwise addition is too fast, ammonia intake is inadequate, and reaction is incomplete, granularity
Very little；When ammonium hydroxide is passed through it is fast when, the concentration of free ammonia is big in reaction solution, increases the instantaneous degree of supersaturation of magnesium hydroxide, is conducive to
Nucleus forming is but unfavorable for growing, particle also very little；When both sides rate of addition is equal and slower, granularity significantly becomes larger, filtering
Speed becomes faster.So magnesium chloride, ammonium hydroxide reaction rate of addition is all appropriate for 10ml/min.
Embodiment 7
Respectively by MgCl2Solution (concentration 3moL/L) carries out single factor experiment, while adds in MgCl2And ammonia spirit,
(MgCl2It is respectively 1 with ammonia molar ratio of material: 2.6), magnesium chloride and ammonium hydroxide reaction rate of addition are all 10ml/min, stir speed
Rate is 150r/min, the influence of 80 DEG C of reaction temperature, reaction time mainly to magnesium conversion ratio, but is sent out in inquiry experiment
Existing, reaction time too long product can also be difficult to filter, so experiment other factors are done according to appeal preferred plan, reaction time difference
There is sample 1: 10min；Sample 2: 20min；Sample 3: 30min；Sample 4: 40min；Sample 5: 50min, 6: 60min result of sample
Such as table 8.
Influence of 8 reaction time of table to conversion ratio and filterability
It is easy to see that increasing over time, reaction conversion ratio is gradually increasing, at first 20 minutes, magnesium chloride and ammonia
Water concentration is all high, and the two, which combines, generates a large amount of magnesium hydroxide, as both sides are added dropwise, OH-1And Mg2+Concentration declines in pairs,
Reaction becomes slow, and crystal is slowly grown up.More than after forty minutes, reaction conversion ratio does not almost change, under magnesium hydroxide conversion ratio
Drop, because at this moment almost not generating product and Mg (OH)2Can be anti-molten, grain size is caused to reduce, the sad filter of solution, so by 30 minutes
As optimum reacting time.
This example prepares magnesium hydroxide using ammonia process, and single_factor method considers influence of the different condition to its rate of filtration, looks for
Go out the good process conditions of filterability, the drop chlorine root concentration for next chapter provides facility, it was therefore concluded that as follows：
(1) molar ratio of brine magnesium ion concentration 3.0mol/L, magnesium chloride solution and ammonium hydroxide are 1: 2.6, add in testing
It is all that 10ml/min, stir speed (S.S.) are that the magnesium hydroxide of product amount 30%, which does crystal seed, magnesium chloride and ammonium hydroxide reaction rate of addition,
150r/min, 80 DEG C of reaction temperature, material continue mixing time after adding be 30min, magnesium hydroxide grain size obtained by the reaction is big,
Strainability good (523ml/min), bulk density are high (0.87g/ml).
The chlorinity of magnesium hydroxide made from Examples 1 to 7 is 0.8%.Wherein chlorine is had ignored in the magnesium hydroxide of preparation
Ion concentration, the chlorinity problem made from present invention concern for the first time in magnesium hydroxide.By using following embodiment, carry out
Ageing, washing, it is intended to reduce chlorinity；In addition, following embodiment, by investigating the granularity of magnesium hydroxide, ageing, washing temperature,
Influence of the factors such as ageing, washing time and liquid-solid ratio to reduction chlorine root concentration, best ageing process condition is determined.
The assay method of chlorinity of the present invention is：After washing after separation of solid and liquid, filtrate is proposed to do hydrogen manufacturing magnesia
Mother liquor, then quantitatively adding water portion-wise washing filter cake, vacuum filtration, take a certain amount of filtrate and nitric acid silver reaction, Zhi Daoji every time
Without white precipitate.After drying, take it is a certain amount of weigh with dilute nitric acid reaction to just dissolving, survey its chlorine root concentration.
Embodiment 8
Using made from embodiment 1 (for example, by using No. 3 experimental products), as raw material, (chlorinity exists magnesium hydroxide the present invention
0.8%),
Sample is divided into 1：Without grinding；2：Grind 5min；3：Grind 10min；4：Grind 15min；5：Grind 20min.It puts
Enter liquid to consolidate in the beaker that mass ratio is 2: 1, at 80 DEG C, stir 40 minutes, as a result (chloride content is in original product such as table 9
0.97)。
Influence of 9 milling time of table to chloride content and the rate of filtration
As can be seen from Table 9, magnesium hydroxide milling time is longer, and chloride content is smaller, but has arrived grinding after ten minutes,
Chloride content has almost no change, this is because grinding reduces product granularity, increases and is accumulated with water engaging surface.
Embodiment 9
The present invention has investigated to determine using magnesium hydroxide made from embodiment 1 (for example, by using No. 3 experimental products) as raw material
Best ageing process condition using not grinding, sample is put into the beaker that liquid-solid ratio is 2: 1, respectively 50 DEG C, 60
DEG C, 70 DEG C, 80 DEG C, at 90 DEG C, stir 40 minutes, chloride content such as table 10.
Influence of 10 temperature of table to chloride content and the rate of filtration
As seen from Table 10, start temperature is higher, and chloride content is lower, after 80 DEG C or more, chloride content almost without
Variation.
Temperature increases, and system intermediate ion activity increases, and chlorine root is easier to be dissolved in water；Hereafter temperature rise, product easily gather
Collection, granularity become larger, and easily wrap up chlorine root；Suitable wash temperature is 80 DEG C.
Embodiment 10
The present invention is best to determine using magnesium hydroxide made from embodiment 1 (for example, by using No. 3 experimental products) as raw material
Sample is put into the beaker that liquid-solid ratio is 2: 1 by the optimum process condition of speed of agitator, at 80 DEG C, is reacted 40 minutes, is stirred
It is respectively 50r/min, 100r/min, 150r/min, 200r/min, 250r/min to mix speed, chloride content such as table 11.
Influence of 11 mixing speed of table to chloride content and the rate of filtration
As can be seen from Table 11, mixing speed is bigger, and the content of chlorine root is lower, and as mixing speed 50r/min, precipitation does not have
It stirs and, slowed down under chlorinity.
Mixing speed is fast later, increases chlorine root and water touch opportunity, and chlorinity declines soon, so experimental stirring speed selects
To 250r/min.
Embodiment 11
The present invention as raw material, studies liquid-solid ratio using magnesium hydroxide made from embodiment 1 (for example, by using No. 3 experimental products)
Liquid-solid ratio is respectively 1,2,3,4,55 kinds of samples by optimum process condition, and at 80 DEG C, 250r/min is stirred after forty minutes, is obtained
To chloride content such as table 12.
Influence of 12 liquid-solid ratio of table to chloride content and the rate of filtration
See in table 12, liquid-solid ratio is bigger, and chloride content is only slightly decreased, and chlorine root is more during liquid-solid ratio 1: 1, and reason can
Can be that water is very little compared to solid, after stirred, some solids are not in contact with water.
Embodiment 12
The present invention studies mixing time using magnesium hydroxide made from embodiment 1 (for example, by using No. 3 experimental products) as raw material
To the optimum process condition of chloride content by the sample of liquid-solid ratio 2: 1 at 80 DEG C, mixing speed is reached under 250r/min, the reaction time
Respectively 10min；20min；30min；40min；50min, as a result such as the following table 13.
Influence of 13 mixing time of table to chloride content and the rate of filtration
It is analyzed by table 13, mixing time is longer, and chloride content is lower, but to after 40 minutes, variation is just less apparent,
This is because stirring is more long, magnesium hydroxide grain size is smaller, and the dissolving of chlorine root is more thorough.In view of filtering situation, choosing stirring is tested
40 minutes time is best.
Single-stage washing can achieve the effect that certain, but the chlorinity of obtained magnesium hydroxide is unstable, in many cases, washes
The chlorinity of magnesium hydroxide after washing can not be down to 0.3% hereinafter, technique is unstable,
Embodiment 13
Schematic diagram as shown in Figure 2,
The slurry of settling tank solid content 500kg/m3 is pumped by the flow of 30m3/h in No. 1 aging tank, while No. 2 ageings
Tank overflow washing lotion (60m3/h) also enters in No. 1 aging tank, and ageing sedimentation separation, supernatant are stirred in the aging tank
(60m3/h) is incorporated to mother liquor and goes to ammonia still process workshop section, and the control of bottom material slurry solid content is pumped into No. 2 aging tanks, while No. 3 old in 30kg/m3
Change tank washing lotion and be also stirred ageing sedimentation separation into No. 2 aging tanks, the rest may be inferred by analogy, ammonium root, chloride content such as table 14；Single tank
In washing process temperature be 80 DEG C；Speed of agitator is 250r/min；It is 1: 2 to wash solid-to-liquid ratio.
The influence of 14 multistage counter current of table sedimentation washing ammonium root chloride content
Settling tank free ammonia content general control is in 2kmol/m3, it is assumed that the free ammonia in 1,2,3,4,5, No. 6 aging tank
Content is respectively C1, C2, C3, C4, C5, C6, then following relationship is set up：
C1=(30 × 2+60C2)/90=(2+2C2)/3 (1)
C2=(30C1+60C3)/90=(C1+2C3)/3 (2)
C3=(30C2+60C4)/90=(C2+2C4)/3 (3)
C4=(30C3+60C5)/90=(C3+2C5)/3 (4)
C5=(30C4+60C6)/90=(C4+2C6)/3 (5)
C6=30C5/90=C5/3 (6)
C1=63C6, C2=31C6, C3=15C6, C4=7C6, C5=3C6
C1=63C6, C2=31C6 are substituted into (1) formula
63C6=(2+2 × 31 C6)/3
C6=0.01575kmol/m3
I.e. after 6 aging tank wash agitations are aged, free ammonia content is fallen below by the 2kmol/m3 of raw material in washing lotion
0.01575kmol/m3, according to the washing effect of above-mentioned ammonia, chlorine ion concentration is 6.254kmol/m3 in settling tank, is also passed through
After 6 aging tank wash agitation ageings, chlorine ion concentration should be reduced to：
(6.254/2) × 0.01575=0.04925kmol/m3=1.748kg/m3
Assuming that No. 6 aging tank bottom material slurries (solid content 500kg/m3) moisture content after centrifuge dewatering is 10%, then not
When washed, chloride content is in magnesium hydroxide products：(1.5m3 × 1.748kg/m3)/15000kg=0.01748%.
It was found that, washed, had following using the multi-stage countercurrent of embodiment 13 by embodiment 13 and embodiment 8~12
Further advantage：
Chlorine root is compared between 0.25-3.2% compared to single-stage washing, the washing methods settled using continuous multi-stage adverse current,
Magnesium hydroxide slurry is after 6 grades of ageings, and 1. the chloride content in product can be preferably minimized level and can drop chloride content
To 0.2% (0.01748) hereinafter, and it is more stable, be expected in this way the product quality for thoroughly solving to always exist in the past (especially
Chloride content) it is unstable the problem of.
2. for magnesium hydroxide slurry after 6 grades of ageings, the free ammonia content in slurry can drop to 0.01575mol/L, then lead to
It crosses and does not have ammonia spilling when centrifuge is separated by filtration, centrifuge operations environment is made to be greatly improved.
3. magnesium hydroxide slurry by 6 grades ageing after, centrifuge detach when need not add water washing (or plus it is minimal amount of
Water), Direct Dehydration can meet product quality requirement, and the processing capacity of such centrifuge is greatly increased, can be greatly lowered
Energy consumption.
4. magnesium hydroxide slurry, by the way that water is added continuously to be aged, washing amount of water is few and constant, it can be ensured that distilled ammonia liquid into
The stabilization divided, thus may insure the stabilization of production technology.
5. the problem of can not having to take care 6 304 stainless steel of desk centrifuge.
6. the equipment investment expense newly increased is few.
Claims (10)
1. a kind of preparation method for reducing magnesium hydroxide chlorinity, which is characterized in that by the pending hydroxide containing chlorine impurity
Magnesium carries out the agitator treating of single-stage；Or the multi-stage countercurrent agitator treating through chlorine removal system, obtain dechlorination magnesium hydroxide；
The chlorine removal system includes multistage dechlorination unit；Each dechlorination unit is both provided with the entrance and exit, clear of magnesium hydroxide
The outlet of washing lotion and entrance；Each dechlorination unit is serially connected by the outlet and entrance of magnesium hydroxide, wherein, the first order is removed
The magnesium hydroxide entrance of chlorine unit is the inlet port of pending magnesium hydroxide, and the magnesium hydroxide of afterbody dechlorination unit exports
Extraction mouth for the magnesium hydroxide after dechlorination；
The rinse liquid outlet of the dechlorination unit of the first order is the extraction mouth of the cleaning solution after cleaning, the dechlorination unit of afterbody
Clear liquid liquid entrance is the inlet port of clear water；The outlet of the cleaning solution of other dechlorination units at different levels and the upper level being respectively in series
The filter washing water inlet connection of dechlorination unit；
Magnesium hydroxide enters the chlorine removal system by the magnesium hydroxide entrance of first order dechlorination unit, and clear water is by afterbody
Feed liquid port enters chlorine removal system；Magnesium hydroxide from the first order dechlorinate unit to afterbody dechlorinate unit motion；Cleaning solution by
Afterbody agitator treating, agitator treating in each dechlorination unit to first order dechlorination unit motion, magnesium hydroxide and clear liquid liquid
Magnesium hydroxide afterwards by afterbody dechlorination unit magnesium hydroxide export extraction, cleaning solution by the first order dechlorination unit cleaning
Liquid outlet extraction.
2. the preparation method of magnesium hydroxide chlorinity is reduced as described in claim 1, which is characterized in that the magnesium hydroxide
Outlet be arranged on dechlorination unit lower part；The entrance of the magnesium hydroxide is arranged on the top of dechlorination unit；
The entrance and exit of the cleaning solution is arranged at the top of dechlorination unit, and the outlet of the cleaning solution and entrance are set
Put the relative position on dechlorination unit top.
3. the preparation method of magnesium hydroxide chlorinity is reduced as described in claim 1, which is characterized in that the pending hydrogen
The bulk density 0.8-2.0g/ml of magnesia；Further preferably 1.2-1.5g/ml.
4. the preparation method of magnesium hydroxide chlorinity is reduced as described in claim 1, which is characterized in that the pending hydrogen
The chlorine impurity content of magnesia is 0.6-0.9%.
5. as Claims 1 to 4 any one of them reduces the preparation method of magnesium hydroxide chlorinity, which is characterized in that stirring
In washing process, the cleaning solution of single-stage agitator treating process is clear water；
During agitator treating, magnesium hydroxide is followed by stirring and washing with cleaning solution；
Wherein, the solvent and solute weight ratio of magnesium hydroxide and cleaning solution is 1~5: 1；Further preferably 2~4: 1；
In each dechlorination unit, speed of agitator is not less than 50r/min；Preferably 50~250r/min；
The agitator treating time is not less than 10min in each dechlorination unit；Preferably 10-60 minutes.
6. the preparation method of magnesium hydroxide chlorinity is reduced as claimed in claim 5, which is characterized in that the chlorine removal system
In, the series connection series of the dechlorination unit is 2~10 grades；Preferably 3~6 grades.
7. the preparation method of magnesium hydroxide chlorinity is reduced as claimed in claim 6, which is characterized in that the pending hydrogen
Magnesia is ground processing in advance before washing, and milling time is 5~20min, further preferably 5~10min；
The temperature of agitator treating process is 50~90 DEG C；Preferably 60~80 DEG C.
8. as claim 1~7 any one of them reduces the preparation method of magnesium hydroxide chlorinity, which is characterized in that described
The preparation process of pending magnesium hydroxide be：
Magnesium chloride solution and ammonium hydroxide are added drop-wise to together in the ammonium hydroxide added with magnesium hydroxide crystal seed-chloride buffer system, stirred
Pending magnesium hydroxide is made in reaction.
9. the preparation method of magnesium hydroxide chlorinity is reduced as claimed in claim 8, which is characterized in that the magnesium chloride is molten
The molar concentration of liquid is 1-4moL/L；A concentration of 10-13.3mol/L of ammonium hydroxide；Magnesium chloride solution and ammonium hydroxide add molar ratio
It is 1: 2-1: 8；
The magnesium hydroxide seed load is the 10~40% of product quality.
10. the preparation method of magnesium hydroxide chlorinity is reduced as claimed in claim 8, which is characterized in that be stirred to react process
Temperature be 40~80 DEG C；
The speed of agitator being stirred to react is not less than 50r/min；
The time is stirred to react as 10~40min.
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| CN109133124A (en) * | 2018-08-24 | 2019-01-04 | 中国科学院青海盐湖研究所 | A kind of magnesium hydroxide continuously washs and isolated method and system |
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|---|---|---|---|---|
| CN102050473A (en) * | 2009-11-10 | 2011-05-11 | 沈新财 | Process for preparing flame retardant grade magnesium hydroxide by ammonia method |
| CN106477602A (en) * | 2016-10-13 | 2017-03-08 | 青海百事特镁业有限公司 | A kind of preparation technology of high-purity low oxychloride magnesium |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102050473A (en) * | 2009-11-10 | 2011-05-11 | 沈新财 | Process for preparing flame retardant grade magnesium hydroxide by ammonia method |
| CN106477602A (en) * | 2016-10-13 | 2017-03-08 | 青海百事特镁业有限公司 | A kind of preparation technology of high-purity low oxychloride magnesium |
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| 孙体昌: "《固液分离》", 31 August 2011 * |
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| CN109133124A (en) * | 2018-08-24 | 2019-01-04 | 中国科学院青海盐湖研究所 | A kind of magnesium hydroxide continuously washs and isolated method and system |
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