CN106044806A - Method for preparing magnesium hydroxide from magnesite and magnesium hydroxide prepared with method - Google Patents
Method for preparing magnesium hydroxide from magnesite and magnesium hydroxide prepared with method Download PDFInfo
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- CN106044806A CN106044806A CN201610393799.4A CN201610393799A CN106044806A CN 106044806 A CN106044806 A CN 106044806A CN 201610393799 A CN201610393799 A CN 201610393799A CN 106044806 A CN106044806 A CN 106044806A
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- magnesium hydroxide
- magnesite
- mineral aggregate
- rotary kiln
- light calcined
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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
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/60—Particles characterised by their size
- C01P2004/61—Micrometer sized, i.e. from 1-100 micrometer
Abstract
The invention relates to a method for preparing magnesium hydroxide from magnesite and magnesium hydroxide prepared with the method. The method comprises steps in sequence as follows: the magnesite is calcined in an external combustion type rotary kiln, and light calcined magnesium hydroxide is obtained; the content of calcium sulfate in the light calcined magnesium hydroxide is measured; slurry is prepared from the light calcined magnesium hydroxide by the aid of distilled water, barium chloride is added to the slurry and stirred for reaction, a liquid is filtered out, drying is performed, and dried magnesium hydroxide is obtained; coarse particles of the dried magnesium hydroxide are screened out, and magnesium hydroxide with a small particle size is prepared, wherein the magnesite for calcination has the particle size not larger than 20 mm; primary air speed of the external combustion type rotary kiln is 50-55 m/s, and the particle size of pulverized coal is 5-10 mm; secondary air speed is 16-18 m/s; a ratio of the distilled water to the light calcined magnesium hydroxide is (10:1)-(15:1); a molar ratio of barium chloride to calcium sulfate is (2:1)-(3:1). The invention further provides magnesium hydroxide prepared with the method. According to the method, magnesium hydroxide with the small particle size can be prepared from the magnesite through calcination in the external combustion type rotary kiln.
Description
Technical field
The present invention relates to a kind of use external-burning calcined by rotary kiln magnesite to prepare the method and thus of light calcined magnesia
The light calcined magnesia prepared.
Background technology
Magnesium hydroxide purposes widely, is the excellent flame retardant of plastics, rubber etc., is the rubber and plastic row generally acknowledged at present
Industry has fire-retardant, press down cigarette, fill triple functions outstanding fire retardant.As flue gas desulfurization agent in terms of environmental protection, can replace
Caustic soda and Calx are as the nertralizer of acid-bearing wastewater.Also act as oil dope, play anticorrosion and desulfidation.It addition, also may be used
For electron trade, medicine, Saccharum Sinensis Roxb. refined, make insulation material and manufacture other magnesium salt products.For example, it is possible to by hydroxide
Magnesium is used as fire retardant or fire-retardant filler joins in polyethylene, polypropylene, polystyrene and ABS resin, thus gives good
Fire-retardant and smoke elimination effect；Magnesium hydroxide can be also used for the manufacture of magnesium salt, refined, the pharmaceuticals industry of Saccharum Sinensis Roxb., daily-use chemical industry etc.；Hydrogen
Magnesium oxide is also used as antiacid, permeability aperient etc..At present, magnesium hydroxide is widely used in rubber, chemical industry, builds
In material, plastics and electronics, unsaturated polyester (UP) and the macromolecular material such as paint, coating.Particularly to mining air duct coating cloth,
PVC whole core conveyer belt, flame-retardant aluminum plastic plate, fire-retardant tarpaulin, PVC cable material, mine cable sheath, cable accessory fire-retardant,
Smoke elimination antistatic, can replace aluminium hydroxide, has excellent flame retardant effect.Magnesium hydroxide, compared with similar inorganic combustion inhibitor, has
There is more preferable smoke suppressing effect.Magnesium hydroxide is producing, is using and all unharmful substance discharges in waste procedures, and can also neutralize
The acidity produced in combustion process and corrosive gas.Owing to magnesium hydroxide and substrate resin have the good compatibility, it it is thermoplastic
Property resin and the excellent fire retardant of rubber, be commonly used for additive flame retardant or fire-retardant filler in adhesive.It is commercially used for
Manufacture that magnesium salt, activated magnesia, medicine, fine ceramics, insulation material, Saccharum Sinensis Roxb. is refined, flue gas desulfurization agent, oil product anticorrosion are added
Agent, acid-bearing wastewater nertralizer, colour kinescope cone glass coating etc..Owing to magnesium hydroxide has colourless, nontoxic, tasteless, without rotten
The character such as erosion property, are environmental type macromolecular material additives.There is good lamellar or the hydroxide of threadiness crystal form
Magnesium, preferably can mate with raw material, and not affect the physical propertys such as raw-material intensity, thus improves scratching of macromolecular material
Qu Qiangdu and elongation percentage.Either for fire retardant, or the additive for macromolecular material, either for food, medicine
Product or industrial products, the size of magnesium hydroxide is the factor of the primary importance of the performance affecting products obtained therefrom all the time, especially makes
Preparing in the case of nano material especially true with magnesium hydroxide, the magnesium hydroxide being therefore highly desirable to prepare low particle diameter produces
Product.
The synthetic method of magnesium hydroxide mainly has salt lime method, salt Ammonia Process, concentrated seawater extraction method and aqua oxidation
Magnesium processes etc..But, there is the shortcoming that impurity is many, particle size is big in the magnesium hydroxide that salt lime method prepares；Salt Ammonia Process is deposited
The shortcomings such as, washing cycle length low at yield, and the magnesium hydroxide that particle diameter is little cannot be prepared；Concentrated seawater extraction method equally exists miscellaneous
The problem that matter is many, particle diameter is big；Aqua oxidation magnesium processes presently, there are that magnesium hydroxide aquation is bigger than low, magnesium hydroxide particle diameter and technique
The problems such as step is various.
Magnesite is the mineral name of magnesium carbonate.It is the natural alkalescence raw mineral materials with magnesium carbonate as main component.Work
In industry, the magnesite of application is actually through the magnesite of processed, the magnesite product crossed through processing, generally becomes
For magnesite.China's magnesite resource enriches, distributed more widely, and quality is high, and reserves are big.Sparry magnesite is mainly in Yingkou, Liaoning Province
Dashiqiao to Haicheng City one carries, and reserves account for the 80% of the whole nation.
The crystal structure of magnesite and character.Magnesite is common carbonate mineral, and the nothing such as calcite, dolomite
Aqueous carbonate salt mineral together, are mineralogically referred to as calcite race mineral.Calcite race crystallizable mineral structure is similar, sun from
Sub-radius is close, can form isomorphism widely, has again similarity in physical property, often closely symbiosis and be mingled in
Rise.
The chemical composition of magnesite.The main chemical compositions of sparry magnesite stone is magnesium oxide, submember be calcium oxide,
Silicon oxide, iron sesquioxide, aluminium sesquioxide.Content of magnesia is generally 35%-47%, calcium oxide 0.2%-4%, silicon oxide
The content of 0.2%-8%, iron sesquioxide and aluminium sesquioxide is typically below 1%.Trace element has P, Mn, Ti, Cr, Ni etc.
Kind more than 20, kind is more, but without economic worth.
The physicochemical change of magnesite calcining.The chemical composition of giobertite, in addition to magnesium oxide, still contains three oxidations two
The impurity such as ferrum, aluminium sesquioxide, silicon oxide, calcium oxide, the basic physicochemical change occurred in calcination process: is magnesite
The decomposition in ore deposit, the crystal growth of periclase crystal；Two is under high temperature action, between oxide impurity or oxide impurity and oxygen
Change magnesium interaction and form new mineral.
Calcining is mineral or the thermal dissociation of synthetic compounds or crystal phase transition process.Now, compound is at a certain temperature
Thermal dissociation, for forming better simply compound or crystal phase transition occurring, is beneficial to subsequent treatment or making is selected product to be changed into be suitable to
The form that user needs.The change of magnesite calcination process, can be summarized as following some: the crystal grain of magnesite when (1) 500 DEG C
Crackle occurs；The magnesium oxide of homogenizing occurs to the inside of magnesite crystal grain deeply when (2) 550 DEG C around magnesite granule；(3)
When 650 DEG C, magnesite disappears, and magnesium oxide local presents anisotropism；When (4) 1100 DEG C, form small magnesioferrite at periclase
Inclusion enclave, the most therefore its color becomes brown.Temperature continues to be increased to 1400 DEG C and can't see what change, simply periclase brown
Deepen.
Selecting calcining manners and control light roasting temperature is the light calcined magnesia important means obtaining and having good aquation activity.
Along with the raising of calcining heat, the specific surface area of MgO is remarkably decreased.When temperature is more than 1300 DEG C, MgO recrystallization speed adds
Hurry up, dispersion drastically declines, and activity is deteriorated.Using different calcining manners and calciner at that same temperature is also impact
The key factor of MgO activity.
At present, the device being produced light calcined magnesia by high-temperature calcination magnesite mainly has reflecting kiln or shaft furnace, wherein adopts
It is commonly used method with shaft furnace calcined magnesite to produce light calcined magnesia, but the method typically uses bulk magnesite
Enter kiln calcining.Owing to not having constant temperature to keep process in this technical process, and it is big to enter stove magnesite nugget, easily occurs in the burning of surface
The phenomenon of heart underburnt, therefore there is streaking and the shortcoming such as activity is low in gained light calcined magnesia.Further, since by furnace binding
And the restriction of process conditions, there is the requirement of any to entering furnace charge block size, as shaft furnace enters furnace charge block dimensional requirement not less than 40
Millimeter, so that large quantities of undersized material block and fine ore can not be used.On the other hand, during mining, output granularity is less than
The Ore of 25 millimeters accounts for 40 to 45%, and this part Ore is usually discarded or is used for paving the way, while causing the huge wasting of resources
Also take up soil, pollute environment, cause serious environmental issue.
The device being produced light calcined magnesia by high-temperature calcination magnesite also has tunnel cave, tunnel cave to be the continuous of modernization
The Thermal Equipment that formula is burnt till, usually one long linear tunnel, fixing wall and vault, bottom are arranged at its both sides and top
Kiln car is run on the track laid.Combustion apparatus is located at the both sides, middle part of tunnel cave, constitutes fixing thermal zone burn till
Band (it is equipped with clinkering zone air-supply arrangement), the high-temperature flue gas that burning produces is in tunnel cave front end chimney or the effect of air-introduced machine
Under, flowing along tunnel to kiln hood direction, the goods in preheating enters kiln the most step by step, this section constitutes the pre-of tunnel cave
The torrid zone.Kiln tail at tunnel cave blasts cold wind, the goods of latter a section in cooling tunnel kiln, and the cold wind blasted flows through goods and added
After heat, then extracting the thermal source sending into exsiccator as dry green compact out, this section just constitutes the cooling zone of tunnel cave.Use at present
The mode of tunnel cave calcining bulk magnesite, the shortcoming that there is calcination time length, and often make surface burning and internal life
Burn, all will make the activity reduction of light-magnesite powder.
Therefore, the art there is also utilizing external-burning calcined by rotary kiln magnesite to prepare the light of high aquation activity
Burn oxidation magnesium oxide with prepared by hydration process the magnesium hydroxide of low granularity the needs of method.
Summary of the invention
In order to solve the light-burned oxygen for preparing low granularity utilizing external-burning calcined by rotary kiln magnesite to prepare high-quality
Changing the said one in the presence of magnesium or multiple problem, it is light that the present invention provides a kind of use magnesite preparation in first aspect
The method of burned magnesium oxide, it is characterised in that described method in turn includes the following steps:
A () uses external-burning calcined by rotary kiln magnesite to obtain light calcined magnesia；
B () measures the content of the calcium sulfate in described light calcined magnesia；
C () uses distilled water that magnesium oxide is prepared slurry, and add barium chloride in slurry, the temperature of 45 DEG C to 55 DEG C
Stir 6 to 7 hours with the speed of 400 to 500 revs/min, so that magnesium oxide and distilled water reaction, then filter liquid, prepare
Rough magnesium hydroxide；
D rough magnesium hydroxide is dried to water content less than 1 weight % by () at 45 DEG C to 55 DEG C, prepare dry hydrogen oxidation
Magnesium；With
E () uses the mesh screen with the mesh that aperture is less than 200 microns to sieve dry hydrogen magnesium oxide, screen out thick
Granule, thus prepare the magnesium hydroxide of low particle diameter；
Wherein:
Described external-burning rotary kiln has the particle diameter of no more than 20 millimeters for the magnesite calcined；
The wind speed of the First air for spray feed coal dust of described external-burning rotary kiln be 50 meter per seconds to 55 meter per seconds, coal dust
Granularity is 5 millimeters to 10 millimeters；
The wind speed of the secondary wind of described external-burning rotary kiln is controlled as 16 meter per seconds to 18 meter per seconds；
The envelope-bulk to weight ratio of the volume of the distilled water counted with milliliter and magnesium oxide in gram is 10:1 to 15:1；
Barium chloride is 2:1 to 3:1 with the mol ratio of calcium sulfate.
The present invention provides the magnesium hydroxide prepared by the method described in first aspect present invention in second aspect.
The present invention mainly prepares the light calcined magnesia of high-quality by improving the technological parameter of external-burning rotary kiln, and to
Light calcined magnesia adds barium chloride and prepares the magnesium hydroxide with low particle diameter.
Detailed description of the invention
As it has been described above, the present invention first aspect provide a kind of use magnesite to the method preparing light calcined magnesia,
It is characterized in that, described method in turn includes the following steps:
A () uses external-burning calcined by rotary kiln magnesite to obtain light calcined magnesia；
B () measures the content of the calcium sulfate in described light calcined magnesia；
C () uses distilled water that magnesium oxide is prepared slurry, and add barium chloride in slurry, the temperature of 45 DEG C to 55 DEG C
Stir 6 to 7 hours with the speed of 400 to 500 revs/min, so that magnesium oxide and distilled water reaction, then filter liquid, prepare
Rough magnesium hydroxide；
D rough magnesium hydroxide is dried to water content less than 1 weight % by () at 45 DEG C to 55 DEG C, prepare dry hydrogen oxidation
Magnesium；With
E () uses the mesh screen with the mesh that aperture is less than 200 microns to sieve dry hydrogen magnesium oxide, screen out thick
Granule, thus prepare the magnesium hydroxide of low particle diameter；
Wherein:
Described external-burning rotary kiln has the particle diameter of no more than 20 millimeters for the magnesite calcined；
The wind speed of the First air for spray feed coal dust of described external-burning rotary kiln be 50 meter per seconds to 55 meter per seconds, coal dust
Granularity is 5 millimeters to 10 millimeters；
The wind speed of the secondary wind of described external-burning rotary kiln is controlled as 16 meter per seconds to 18 meter per seconds；
The envelope-bulk to weight ratio of the volume of the distilled water counted with milliliter and magnesium oxide in gram is 10:1 to 15:1；
Barium chloride is 2:1 to 3:1 with the mol ratio of calcium sulfate.
The present invention provides the magnesium hydroxide prepared by the method described in first aspect present invention in second aspect.
In some embodiments, the temperature of step (c) and/or step (d) is 50 DEG C.
In other embodiment, the mesh screen in step (e) has the mesh of 100 micron pore size.
In some preferred embodiments, described light calcined magnesia is by including that following method such as prepares:
(1) magnesite powder is broken into the ore deposit of no more than 20 millimeters (being such as not more than 20 millimeters, 18,15 or 10 millimeters)
Material；
(2) described mineral aggregate is preheated in preheating zone so that mineral aggregate temperature reach 280 DEG C to 320 DEG C (such as 280,290,
300,310 or 320 DEG C)；
(3) by through preheating mineral aggregate clinkering zone 950 DEG C to 1300 DEG C (such as 950 DEG C, 960 DEG C, 970 DEG C, 980
DEG C, 990 DEG C, 1000 DEG C, 1100 DEG C, 1200 DEG C or 1300 DEG C) calcining 30 minutes to 50 minutes (such as 30 minutes, 40 minutes,
50 minutes；
(4) by through calcining mineral aggregate cooling zone be cooled to 100 DEG C to 150 DEG C (such as 100 DEG C, 110 DEG C, 120 DEG C,
130 DEG C, 140 DEG C or 150 DEG C)；
(5) mineral aggregate cooled down through step (4) is naturally cooled to room temperature；With
(6) mineral aggregate of room temperature is crushed to granularity for no more than 100 microns (be such as not more than 100 microns, be not more than 90 micro-
Rice, no more than 80 microns, no more than 70 microns, no more than 60 microns, no more than 50 microns), obtain light calcined magnesia product；
Wherein: the wind speed for the First air of spray feed coal dust be 50 meter per seconds to 55 meter per seconds (such as 50 meter per seconds, 51 meters/
Second, 52 meter per seconds, 53 meter per seconds, 54 meter per seconds or 55 meter per seconds), the granularity of coal dust be 5 millimeters to 10 millimeters (such as 5 millimeters, 6
Millimeter, 7 millimeters, 8 millimeters, 9 millimeters or 10 millimeters)；The blast velocity control of secondary wind be 16 meter per seconds to 18 meter per seconds (16 meter per seconds,
17 meter per seconds or 18 meter per seconds).
Some preferred embodiment in, in step (1), magnesite powder is broken into the mineral aggregate of no more than 15 millimeters.
Some preferred embodiment in, in step (3), clinkering zone 950 DEG C will through preheating mineral aggregates forge
Burn 50 minutes.Other preferred embodiment in, in step (3), clinkering zone 1300 DEG C calcine 30 minutes.
Some preferred embodiment in, in step (2), with the speed of 5 DEG C/min, mineral aggregate is preheated to 300 DEG C.
Other preferred embodiment in, in step (4), by through calcining mineral aggregate with the speed of 5 DEG C/min, mineral aggregate is cold
But to 120 DEG C.
Some preferred embodiment in, the gradient of described external-burning rotary kiln is 3.5% to 3.8%, for example,
3.5%, 3.6%, 3.7% or 3.8%.
The present invention provides the magnesium hydroxide prepared by the method described in first aspect present invention in second aspect.
External-burning rotary kiln refers to rotary calcining kiln, belongs to building equipment class.In many such as building materials, metallurgy, chemical industry, environmental protection
In production industry, it is widely used external-burning rotary kiln and solid material is carried out machinery, physical or chemical treatment.
The structure of external-burning rotary kiln is known, generally comprises cylinder, wheel belt, support roller, gear wheel, sealing device, transmission
Device and auxiliary device (formation of the axial flow blower of such as clinkering zone, beneficially kliner coating, thus protect cylinder；Sensing barrel temperature
Barrel temperature sensor and for measuring ammeter or the power meter etc. of moment).Cylinder is usually by different-thickness steel plate thing
First being rolled into, be inlaid with refractory material such as refractory brick in cylinder, be cased with several roads wheel belt outside cylinder, cylinder becomes constant slope,
It is seated on the support roller corresponding with wheel belt.Actuating device include gear wheel, little gear, shaft coupling, main gear reducer and mair motor,
Attached reductor and accessory motor.
External-burning rotary kiln needs air-supply.Including providing First air and secondary wind.
First air is typically room temperature wind, is the natural air being forcibly fed in kiln by main burner, by kiln hood once
Blower fan supplies.Oxygen needed for fugitive constituent burns in effect mainly pulverized coal conveying, and coal supply.It is thought that if air quantity mistake
Greatly, absorbing heat after entering kiln, the heat consumption making quantity calcine increases, and the thermal efficiency reduces, and is unfavorable for the discharge of NOx.But, if First air
Very few, fugitive constituent burning is slow, affects burning of coal speed, and therefore, the wind speed of First air is generally 50 meter per seconds to 70 metre per second (m/s)s.
Secondary wind is to not allow material be limited by various conditions in kiln, sets up what post-blast device provided
Wind, because calcining materials is in moving process, the thing section being in surface is heated by convection current and the heat radiation of thermal current, is also subject to
The radiation heating of scorching hot refractory lining；The material pressing close to liner is then directly heated by scorching hot refractory material；It is in heap
Material in the middle of long-pending section is then by the conduction of heat heating of calcining materials self.Thing is trembled and is not stopped to stir because kiln body rotates, and Shi Wu section hands over
For being heated, temperature of charge ratio is more uniform.After setting up post-blast, escape from material the burning required air of volatile matter mainly by
Post-blast supplies.The general cooled machine of secondary wind is preheated to 650 DEG C to 1000 DEG C, after enter kiln, to air-flow produce strong disturbing
Dynamic, the beneficially burning of carbon.The size of convulsion ability in the wind speed size decision kiln of secondary wind, it is considered that, the wind of secondary wind
Speed is too small, and flame is too short, and the wind speed of secondary wind is big, and flame is long, therefore the general length being regulated flame by the wind speed of secondary wind
Degree.The burning velocity of length and coal dust in order to control flame, typically by the blast velocity control of secondary wind 9 meter per seconds to 12 meter/
Second.
But, based on reason as above, in prior art, the wind speed of First air is generally 50 meter per seconds to 70 meter per seconds
In the range of, the wind speed general control of secondary wind is in the range of 9 meter per seconds to 12 meter per seconds.At such First air wind speed and two
Under conditions of secondary wind wind speed, it is impossible to the temperature of the clinkering zone of external-burning rotary kiln is controlled in the applicable light-burned oxidation of generation high-quality
In the range of the temperature (it is generally acknowledged 900 DEG C to 1300 DEG C) of magnesium.The present inventor finds through further investigation, if by First air
Wind speed be limited in not higher than 55 meter per seconds, such as in the range of 50 meters/meter to 55 meter per seconds, and the wind speed of secondary wind is provided
More than 16 meter per seconds, such as, improve to 16 meter per seconds to 18 meter per seconds, then the temperature stabilization of clinkering zone is maintained at calcining preparation
900 DEG C needed for light calcined magnesia are just possibly realized to 1300 DEG C, and use such process conditions to prepare to have
High aquation activity and the light calcined magnesia of burn tinctuer.
In the light calcined magnesia product prepared by magnesite, often contain other impurity component such as calcium sulfate,
If this impurity does not affect what the performance of obtained magnesium oxide usually will not give to remove up hill and dale.The present inventor
If it was unexpectedly observed that adding suitable in slurry when the Preparation of Magnesium Hydroxide Using Magnesium Oxide using the method using the present invention to prepare
During the barium chloride measured, can be to obtain the magnesium hydroxide products with low particle diameter (low D50).Specifically, by light-burned oxidation
Magnesium powder is broken to desired particle size and is such as not more than 100 microns, after the most no more than 80 microns or no more than 50 microns, measures institute
State in light calcined magnesia contained calcium sulphate content, and with the barium chloride of 2:1 to 3:1 and the mol ratio of calcium sulfate to described gently
Burned magnesium oxide adds barium chloride, thus prepares the chloride containing barium raw material for preparing hydro-oxidation magnesium.Then by hydration method
Utilize described chloride containing barium raw material to prepare magnesium hydroxide, thus can be worth the magnesium hydroxide goods of low particle diameter.
Embodiment
Hereafter will utilize embodiment that the present invention is further detailed by way of illustration, but these
Embodiment is not construed as limiting the invention.
The external-burning rotary kiln used in embodiment is purchased from Shanghai with power heavy-duty machinery company limited, and its specification is as follows:
Diameter: 4m；Length: 60m；Gradient: 3.8%；Production capacity: 2500 ton day；
Kiln body rotating speed: 0.41 to 4.07 rev/min；
Main transmission: motor: ZSN4-355-092；Reductor: YNS1110-22.4V.Accessory drive: motor:
Y180L-4；Decelerator: YNS440-45-II.
The magnesite that embodiment is used is from table mountain, Henan, and content of magnesia is 45.89 weight %, theoretical burn tinctuer
Being 51.5%, theoretical aquation activity is 43.2%.(PE250 × 400, purchased from Shanghai with power heavy-duty machinery to use jaw crusher
Company limited) magnesite is broken into the mineral aggregate of the granularity with no more than 20 millimeters, it is then 0.8 by described mineral aggregate at rotating speed
Rev/min the preheating zone of described external-burning rotary kiln be preheated to 300 DEG C with the speed of 5 DEG C/min；By the mineral aggregate through preheating
Calcine 40 minutes at 1030 DEG C at clinkering zone.After calcining, by the mineral aggregate through calcining in cooling zone with the cooling of 5 DEG C/min
Speed is cooled to 120 DEG C, naturally cools to room temperature the most again.Then, room temperature mineral aggregate is crushed to the powder that granularity is 80 microns,
Thus obtain light calcined magnesia product.
Measure aquation activity and the burn tinctuer of gained light calcined magnesia.Wherein, aquation activity characterizes the suction of light calcined magnesia
Outlet capacity, the ability that aquation activity height then reacts with water is high, i.e. the aquation activity of light calcined magnesia is big.Aquation activity determination method
As follows.Weighing weight is the light calcined magnesia of Wi, then with the abundant moistening of water (do not drip and be as the criterion), the most in an oven 150
DEG C dry to 2 hours, then weigh the weight (Wwd) of light calcined magnesia after drying, then calculate aquation by equation below
Activity (A):
A=(Wwd Wi)/WwdX100% (1)
Burn tinctuer characterizes the percentage by weight that magnesite is lost through calcining, and equation below (2) can be used to calculate:
Burn out rate=(W1-W2)/W1X100% (2)
Wherein, W1 is the weight of magnesite before calcining, W2 be corresponding weight magnesite calcining after the light-burned oxygen of gained
Change the weight of magnesium.Result sees table 2.
It addition, in addition to the content that table 1 below and table thereof are betted, carry out in the way of identical with program described in embodiment 1
Embodiment 1 to 14.
Table 1 uses flame temperature and the standard deviation (n=20) thereof of the clinkering zone of different wind speed gained
Note:
*: breeze is crushed to no more than 25 millimeters.
#: mineral aggregate is preheated to 400 DEG C.
Flame temperature is to use from Shanghai the YT-16 external-burning revolution with the dispensing of power heavy-duty machinery company limited in clinkering zone position
The data that kiln temperature measurer records, data every 5 minutes in the middle part of clinkering zone flame central position gather once, for gather 20 times,
Ask calculation meansigma methods and standard deviation (i.e. temperature is partially).
It is suitable for being obtained the calcining needed for light calcined magnesia by magnesite calcining as it can be seen from table 1 stably to obtain
Temperature needs secondary wind speed on the low side and is in the higher secondary wind wind speed of proper range.
The burn tinctuer of the light calcined magnesia obtained by table 2 embodiment 1 to 14 and water activity (n=5).
| Embodiment is numbered | Light calcined magnesia | Burn tinctuer (%) | Water activity (%) |
| 15 | Embodiment 1 | 49.2 | 38.1 |
| 16 | Embodiment 2 | 51.3 | 40.9 |
| 17 | Embodiment 3 | 51.4 | 41.1 |
| 18 | Embodiment 4 | 43.6 | 28.0 |
| 19 | Embodiment 5 | 41.8 | 27.6 |
| 20 | Embodiment 6 | 38.2 | 22.8 |
| 21 | Embodiment 7 | 42.1 | 29.6 |
| 22 | Embodiment 8 | 44.6 | 30.1 |
| 23 | Embodiment 9 | 51.2 | 41.5 |
| 24 | Embodiment 10 | 50.9 | 40.5 |
| 25 | Embodiment 11 | 45.9 | 26.4 |
| 26 | Embodiment 12 | 43.2 | 21.7 |
| 27 | Embodiment 13 | 37.1 | 33.4 |
| 28 | Embodiment 14 | 50.6 | 39.8 |
If from Table 2, it can be seen that excessive and secondary wind the wind speed of the wind speed of First air is too low or too high, can affect
Reduce the degree of calcination (i.e. reducing burn tinctuer) of magnesite, and reduce the light-burned oxygen prepared through external-burning calcined by rotary kiln
Change the aquation activity of magnesium, thus it is speculated that may have relation with temperature and stability thereof.
The light calcined magnesia using section Example 2 and 7 of the present invention to prepare prepares magnesium hydroxide by hydration process.Specifically
Ground is said, the calcium sulphate content measuring the light calcined magnesia that embodiment 2 and 7 prepares is respectively 0.63 mass % and 0.69 weight %.
According to 1:10 w/v (g/ml) by magnesium oxide and distilled water and barium chloride (using without barium chloride as comparison)
Mix and be positioned in the reactor in 50 DEG C of water-baths, stirring 6 hours with the speed of 400 revs/min, filter liquid by sucking filtration
Body, prepares rough magnesium hydroxide.Then it is dried to constant weight (water content is less than 1 weight %) at 50 DEG C, prepares and be dried hydrogen-oxygen
Change magnesium, use 100 micron mesh screen to screen out residue on sieve, obtain final magnesium hydroxide products, and according to HG/T 3607-2007
Method described in (issuing on 04 13rd, 2007, on October 01st, 2007 implements) measures D50.Result shows in table 3 below.
Table 3 utilizes the D50 (micron) of magnesium hydroxide that the light calcined magnesia obtained by embodiment 2 and 7 prepares.
| Embodiment is numbered | Light calcined magnesia | Barium chloride: the molar ratio of calcium sulfate | D50 (micron) |
| 29 | Embodiment 2 | 0 | 9.0 |
| 30 | Embodiment 2 | 1 | 4.4 |
| 31 | Embodiment 2 | 2 | 1.2 |
| 32 | Embodiment 2 | 3 | 1.5 |
| 33 | * embodiment 7 | 0 | 15.0 |
| 34 | Embodiment 7 | 1 | 12.0 |
| 35 | Embodiment 7 | 2 | 8.1 |
| 36 | Embodiment 7 | 3 | 6.8 |
From table 3 it can be seen that when adding appropriate barium chloride, can obtain in the case of without any post processing
The magnesium hydroxide products that particle diameter is much lower.When the mol ratio of barium chloride Yu barium sulfate is 2:1 to 3:1, the hydrogen of embodiment 2 gained
Magnesium oxide product without any post processing, the I series products that D50 can basically reach or specify close to HG/T 3607-2007
Standard.But, if the barium chloride added is too low, D50 is the biggest, thus it is speculated that is probably barium chloride and plays dispersion wherein
The effect of agent.Especially for the light calcined magnesia obtained by embodiment 2, the effect of barium chloride is more significantly.
Claims (10)
1. one kind uses the method that magnesite prepares light calcined magnesia, it is characterised in that described method in turn includes the following steps:
A () uses external-burning calcined by rotary kiln magnesite to obtain light calcined magnesia；
B () measures the content of the calcium sulfate in described light calcined magnesia；
C () uses distilled water that magnesium oxide prepared slurry, and add barium chloride in slurry, the temperature of 45 DEG C to 55 DEG C with
The speed of 400 to 500 revs/min stirs 6 to 7 hours, so that magnesium oxide and distilled water reaction, then filters liquid, prepares thick
Hydrogen manufacturing magnesium oxide；
D rough magnesium hydroxide is dried to water content less than 1 weight % by () at 45 DEG C to 55 DEG C, prepare dry hydrogen magnesium oxide；With
E () uses the mesh screen with the mesh that aperture is less than 200 microns to sieve dry hydrogen magnesium oxide, screen out thick
Grain, thus prepare the magnesium hydroxide of low particle diameter；
Wherein:
Described external-burning rotary kiln has the particle diameter of no more than 20 millimeters for the magnesite calcined；
The wind speed of the First air for spray feed coal dust of described external-burning rotary kiln is 50 meter per seconds to 55 meter per seconds, the granularity of coal dust
It it is 5 millimeters to 10 millimeters；
The wind speed of the secondary wind of described external-burning rotary kiln is controlled as 16 meter per seconds to 18 meter per seconds；
The envelope-bulk to weight ratio of the volume of the distilled water counted with milliliter and magnesium oxide in gram is 10:1 to 15:1；
Barium chloride is 2:1 to 3:1 with the mol ratio of calcium sulfate.
Method the most according to claim 1, it is characterised in that the temperature of step (c) and/or step (d) is 50 DEG C.
Method the most according to claim 1, it is characterised in that the mesh screen in step (e) has the net of 100 micron pore size
Hole.
Method the most according to claim 1, it is characterised in that described light calcined magnesia prepares by the following method:
(1) magnesite powder is broken into the mineral aggregate of no more than 20 millimeters；
(2) described mineral aggregate is preheated in preheating zone, so that mineral aggregate temperature reaches 280 DEG C to 320 DEG C；
(3) mineral aggregate through preheating is calcined 30 minutes to 50 minutes at 950 DEG C to 1300 DEG C at clinkering zone；
(4) 100 DEG C to 150 DEG C will be cooled to through the mineral aggregate of calcining in cooling zone；
(5) mineral aggregate cooled down through step (4) is naturally cooled to room temperature；With
(6) mineral aggregate of room temperature is crushed to granularity and is no more than 100 microns, obtain light calcined magnesia product.
Method the most according to claim 4, it is characterised in that in step (1), is broken into no more than 15 millis by magnesite powder
The mineral aggregate of rice.
Method the most according to claim 4, it is characterised in that in step (2), breeze is preheating to 300 DEG C.
Method the most according to claim 4, it is characterised in that in step (3), will be through pre-at 950 DEG C at clinkering zone
The mineral aggregate of heat is calcined 50 minutes.
Method the most according to claim 4, it is characterised in that the rotating speed of described external-burning rotary kiln be 0.6 rev/min extremely
0.9 rev/min.
Method the most according to claim 4, it is characterised in that in step (4), by the mineral aggregate through calcining with 5 DEG C/minute
Mineral aggregate is cooled to 120 DEG C by the speed of clock.
10. the magnesium hydroxide prepared by the method according to any one of claim 1 to 9.
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| CN108314335A (en) * | 2018-04-18 | 2018-07-24 | 镇江苏博特新材料有限公司 | A kind of light-burned MgO suspension kilns coproduction Mg (OH)2Production technology and device |
| CN111348844A (en) * | 2020-03-12 | 2020-06-30 | 辽宁科大中驰镁建材科技有限公司 | System and process for preparing light-burned magnesia powder by using low-grade high-calcium magnesite |
| CN112066720A (en) * | 2020-08-04 | 2020-12-11 | 广东摩德娜科技股份有限公司 | Cooling method for quenching section of tunnel kiln and tunnel kiln control device |
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