CN100393919C - Method for magnesium hydroxide whisker using giobertite as material - Google Patents
Method for magnesium hydroxide whisker using giobertite as material Download PDFInfo
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- CN100393919C CN100393919C CNB2006100467546A CN200610046754A CN100393919C CN 100393919 C CN100393919 C CN 100393919C CN B2006100467546 A CNB2006100467546 A CN B2006100467546A CN 200610046754 A CN200610046754 A CN 200610046754A CN 100393919 C CN100393919 C CN 100393919C
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- crystal whisker
- magnesium sulfate
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Abstract
The present invention belongs to the technical field of preparation of an inorganic nonmetallic powder material, particularly to a method for preparing magnesium hydroxide crystal whisker with the raw materials of magnesite, sulphuric acid, sodium hydroxide, etc. The method is characterized in that firstly, high-activity magnesia needs to be prepared, and the high-activity magnesia is used as a raw material to prepare alkaline magnesium sulfate crystal whisker; then, the alkaline magnesium sulfate crystal whisker is used as a raw material to prepare magnesium hydroxide crystal whisker by a hydrothermal synthesis method. The obtained crystal whisker product has a fibrous appearance, a smooth and straight surface, large length and uniform fiber thickness. The magnesium hydroxide crystal whisker belongs to a micron grade, and the length diameter ratio is greater than 10. The magnesium hydroxide crystal whisker can be used as a high molecular polymer fire retardant.
Description
Affiliated technical field:
This invention belongs to the inorganic non-metallic technical field of powdered material preparation, and being specially a kind of is the method that raw material is produced magnesium hydroxide crystal whisker with magnesite.
Technical background:
The magnesium hydroxide pulvis is a kind of in the inorganic non-metallic powder body material, because its heat decomposition temperature reaches 340 ℃, and do not discharge toxic and harmful in the decomposition course, compare with other inorganic combustion inhibitors such as aluminium hydroxide, weisspiessglanz, borate, molybdenum compound etc. and to have the good cigarette effect that presses down, therefore be subjected to extensive concern in material flame-retarded technology field.
In the inorganic anti-flaming material that western developed country is produced, flame retardant of magnesium hydroxide has accounted for 30% of ultimate production, it serves to show the important of this kind fire retardant.But when magnesium hydroxide used as fire retardant, its addition reaches more than 40% can obtain the ideal flame retardant effect.So many inorganic powder additive joins and certainly will cause the higher composite high-molecular material of obvious decline, especially requirement of strength of these matrix material machinery mechanical properties almost can't select this kind fire retardant for use in the organic polymer materials such as plastics, rubber.For this reason, how to guarantee to dose that the mechanical mechanics property of matrix material has been unlikely to be significantly reduced to the key of dealing with problems behind the flame retardant of magnesium hydroxide, the magnesium hydroxide of wherein studying and produce fibrous or whisker becomes an important problem.
Aspect the preparation of magnesium hydroxide crystal whisker, many trials were arranged both at home and abroad.It is raw material with fibrous brucite that the people is wherein arranged, and produce fibrous magnesium hydroxide products through separating, but product purity and pattern is subjected to the restriction of natural brucite, and product is unsatisfactory.Also the someone utilizes sulfuric acid leaching filtrate of serpentine to extract magnesium, then prepares the acicular nanometer magnesium hydroxide, and its goods diameter is 5～9nm, and length-to-diameter ratio reaches 15～20, but this kind method preparation technology more complicated.The somebody utilizes magnesium chloride reagent (AR) to make magnesium chloride brine, again with the sodium hydroxide reaction, and preparation acicular nanometer level magnesium hydroxide products, but the product that this method is produced is stable inadequately, and raw materials cost is higher.
It is raw material that this invention adopts magnesite, adopts reasonable process to prepare magnesium hydroxide crystal whisker.Through repetition test, finally invented simple relatively magnesium hydroxide crystal whisker preparation method, even with product purity height, good dispersity and the pattern that a process for preparing.
Summary of the invention
This invention is raw material with magnesite, obtains greater activity magnesium oxide through calcination, makes alkali magnesium sulfate crystal whisker then, is raw material with alkali magnesium sulfate crystal whisker and sodium hydroxide again, produces the magnesium hydroxide crystal whisker material through hydrothermal synthesis reaction.Mainly comprise the raw material preparation in the product preparation process, magnesite calcination, master operations such as synthetic alkali magnesium sulfate crystal whisker and preparation magnesium hydroxide crystal whisker.Now concrete summary of the invention is described below:
1. magnesite calcination.Select that to contain magnesium oxide be raw material by the magnesite that mass percent reaches more than 45% for use, under 600-700 ℃ of temperature calcination 3-6 hour, obtain extra light calcined magnesia with this;
2. alkali magnesium sulfate crystal whisker is produced.To calcine resulting magnesium oxide is raw material, put into water, make magnesium oxide fully disperse to form suspension through the electric mixer stirring, then the add-on of aqueous sulfuric acid by magnesium oxide amount 1/4 (mol ratio) joined in the magnesia magma, hydrothermal synthesis reaction is carried out in the warming while stirring of packing into after fully stirring again in the autoclave of the magnesium oxide that newly makes and vitriolic mixing solutions.During a certain determined value, the constant temperature and pressure insulation is 2-6 hour under this temperature, closes agitator then, stops heating, is cooled to normal temperature in being warmed up to 130-180 ℃ of scope.Take out resultant of reaction, water dilutes dispersion, washing and filtering to resultant, obtains the product alkali magnesium sulfate crystal whisker.Produce the raw material of magnesium hydroxide crystal whisker after this product promptly can be used as, also can directly utilize as the alkali magnesium sulfate crystal whisker finished product through super-dry.
In order to quicken the formation of alkali magnesium sulfate crystal whisker, can put into the fibrous alkali magnesium sulfate crystal whisker crystal seed that reactor forward direction solution adds the rapping plate effect at magnesium oxide and sulfuric acid mixed solution, its add-on is magnesian 2.0% by quality hundred umbers, after dispersed with stirring is even, puts into reactor and carry out hydrothermal synthesis reaction.
In order to control reaction process, temperature rise speed in the reactor can be controlled at 0.2～2.0 ℃/min and be advisable.
In order to obtain the ideal alkali magnesium sulfate crystal whisker, reaction generally changes in 1.0～10.0% scopes with magnesian mass concentration, and stirring intensity changes in 100～500rpm scope.
3. magnesium hydroxide crystal whisker is produced.The alkali magnesium sulfate crystal whisker that makes with former process is a raw material, water is mixed with the uniform alkali magnesium sulfate crystal whisker suspension of concentration, then, the ratio of sodium hydroxide and alkali magnesium sulfate is that 1: 1～1.6 ratio joins aqueous sodium hydroxide solution in the alkali magnesium sulfate crystal whisker suspension in the mole equivalent, again with the alkali magnesium sulfate crystal whisker that makes and sodium hydroxide mixing solutions through in the autoclave of packing into behind the abundant mixing, stir on intensification limit, limit, begins to carry out hydrothermal synthesis reaction.When temperature in the kettle was raised to a certain preset temperature in 130～190 ℃, constant temperature and pressure insulation certain hour stopped heating then and stirs cool to room temperature.Take out resultant of reaction in still, through washing and filtering, final drying obtains finished product.
Produce in the magnesium hydroxide crystal whisker process in the creation of enforcement this invention, the significant parameter that influences product quality comprises factors such as the initial reaction concentration of alkali magnesium sulfate suspension, stirring intensity, temperature of reaction, reaction times.
(1) strength of solution.The length-to-diameter ratio of alkali magnesium sulfate crystal whisker is bigger, and aerated density is less, contains 3 crystal water in the molecule, and when being prepared into alkali magnesium sulfate suspension with water, whisker suspends in water, after its mass concentration reaches certain value, through stir pasty state suspension.If the mass concentration of this kind suspension is on the low side can influence productive rate, too highly will influence product quality.For aqueous sodium hydroxide solution and alkali magnesium sulfate suspension are mixed, its sufficient reacting is carried out, the alkali magnesium sulfate concentration range that the present invention adopts is 1-5%, wherein concentration is defined as can obtaining comparatively ideal effect at 4% o'clock.
(2) stirring intensity.For hydro-thermal reaction can be carried out uniformly, to stir all the time for alkali magnesium sulfate crystal whisker in the reactor of packing into and sodium hydroxide mixing solutions in the reaction process, stirring intensity is 100～400rpm.When wherein stirring intensity is 100～200rpm, can prepare the product of more satisfactory pattern.
Institute's synthetic product is analyzed through the x-ray diffractometer phase structure under the different stirring intensities, and its result shows that stirring intensity is little to the chemical ingredients influence of synthetic product, and it is more complete to illustrate that hydrothermal synthesis reaction carries out.
(3) temperature of reaction.Produce in the process at magnesium hydroxide, the scope of temperature of reaction can be controlled in 130～190 ℃ of temperature ranges.Along with the raising of hydrothermal synthesis reaction temperature, the length of product increases in this scope, and the whisker expansion improves, but diameter of whiskers is almost constant; The purity of synthetic product also will improve with the rising of hydrothermal temperature.Wherein the magnesium hydroxide crystal whisker pattern that is obtained 180 ℃ the time is more satisfactory, and length-to-diameter ratio is bigger, and the expansion of whisker is better, and tiny whisker content is relatively low.Improve 10 ℃ again on 180 ℃ of bases, under the same reaction time conditions, the pattern of whisker does not almost improve.
(4) reaction times.All there is direct influence the hydro-thermal reaction time to synthetic product pattern and phase structure.In 3～6 hours reaction times, along with the reaction times prolongs, the whisker length of synthetic product increases to some extent, and diameter of whiskers is almost constant; The phase structure of whisker much at one.Under 180 ℃, when the reaction times reached 3 hours, whisker morphology was more satisfactory, and length-to-diameter ratio is bigger, the whisker expansion.Utilize x-ray diffractometer to carry out the phase structure analysis for synthetic product, the result shows, the X-ray diffraction peak value of its synthetic product is all corresponding with the d value of JCPDS7-239 magnesium hydroxide standard card, and peak shape is sharp-pointed, the inclusion-free peak exists, and illustrates that reaction product all is the magnesium hydroxide crystal whisker product of complete crystallization.
Adopt DMB5-5 opticmicroscope and SSX-550 sem observation hydro-thermal synthetic product pattern and particle diameter, measure the diameter and the length of fibrous product, thereby can calculate the length-to-diameter ratio of product; Utilize PW3040 type x-ray diffractometer can detect the phase structure of synthetic product.
Compare with the technological method of producing magnesium hydroxide crystal whisker in the past, this invention has following advantage:
(1) raw material sources are extensive.China is one of maximum country of high-quality magnesite reserves.With it is raw material, can obviously reduce the production cost of magnesium hydroxide crystal whisker.
(2) technology is simple.Whole technological process is divided into 3 big operations, and the correlation parameter of the needs control of each operation is fewer, operation easily.
(3) production unit is more single.Stoving oven, autoclave and drying plant are the big main equipments of three in the whole growth technology, and all the other are large-scale hopper, mixing and the whipping device etc. of acid and alkali-resistance, so reduced investment, the industrialization instant effect, and main equipment is realized control automatically easily.
(4) magnesium hydroxide crystal whisker that utilizes present method to produce is filled up the domestic production blank, dose in the high molecular polymers such as rubber, plastics a consumption that can reduce rubber, plastics, reduce cost, two can significantly improve the fire-retardant and mechanical mechanics property of material, reduce the generation of fire failure, for society reduces unnecessary loss, improve people's sense of security and quality of life.
Embodiment 1
The magnesite that utilizes somewhere, Liaoning to be produced is raw material, produces magnesium hydroxide crystal whisker.
The magnesite Chemical Composition is as shown in the table:
Magnesite Chemical Composition table
| Component | MgO | CaO | Fe 2O 3 | S | SiO2 | CO 2And loss on ignition |
| Massfraction % | 47.11 | 0.64 | 0.33 | 0.03 | 0.02 | 51.87 |
700 ℃ of temperature lower calcinations 3 hours, obtain extra light calcined magnesia with this;
With calcining gained magnesium oxide is raw material, be mixed with concentration and be 10.0% magnesia magma, after stirring fully disperses solution, the add-on of aqueous sulfuric acid by magnesium oxide amount 1/4 (mol ratio) joined in the magnesia magma, again in fully stirring the autoclave of it being packed into after forming homogeneous mixture solotion, stir on intensification limit, limit, and stirring intensity is decided to be 200rpm, carries out hydrothermal synthesis reaction; When being warmed up to 180 ℃, insulation is 4 hours under the constant temperature and pressure condition, then, stops heating and stirring, is cooled to normal temperature.Take out resultant of reaction, resultant is diluted dispersion, filters and put into loft drier carry out drying, make alkali magnesium sulfate crystal whisker.
Through observation by light microscope, it is fibrous that alkali magnesium sulfate crystal whisker is, and length is bigger, belongs to micron order; Fiber surface is smooth, and straight nothing is crooked; Diameter of whiskers is 0.5～1.5 μ m, and whisker length is 20～100 μ m, and very thin expansion.The X-ray diffracting spectrum analytical results shows: the main diffraction peak 2 θ values of hydro-thermal synthetic product (by by force to weak) are: 17.44,23.00,13.080,45.720,34.62,40.10,23.46,30.200,26.200,36.560.Can be determined by optical microscope photograph and X-ray diffracting spectrum: hydro-thermal synthetic product is an alkali magnesium sulfate crystal whisker, complete crystallization.Its chemical molecular formula is MgSO
45Mg (OH)
23H
2O.
It is 4% alkali magnesium sulfate crystal whisker suspension that water is mixed with mass percent concentration, then the add-on of aqueous sodium hydroxide solution by alkali magnesium sulfate 1.4 times (mol ratios) joined in the alkali magnesium sulfate crystal whisker suspension, after mixing, in its autoclave of packing into, stirring intensity is decided to be 200rpm, warming while stirring begins to carry out hydrothermal synthesis reaction.When temperature in the kettle was raised to 180 ℃, constant temperature and pressure insulation 3 hours stopped heating and stirring then, naturally cools to room temperature.Take out resultant of reaction in still, through washing and filtering, final drying makes finished product.
This institute obtains the pattern of synthetic product and XRD spectra and opticmicroscope pattern and detects photo and show: the synthetic product pattern is fibrous, and length is bigger, belongs to micron order; Fiber surface is smooth, and straight nothing is crooked; Length-to-diameter ratio all＞10, and very thin evenly.The main X-diffraction peak d value (descending) of synthetic product is respectively: 4.72587,2.71565,2.35743,1.79003,1.57104,1.49237 and 1.37050, corresponding one by one with the d value of JCPDS7-239 magnesium hydroxide standard card, peak shape is sharp-pointed, and the inclusion-free peak exists.Illustrate that the hydro-thermal synthetic product is a magnesium hydroxide crystal whisker, complete crystallization, purity height.
Claims (3)
1. one kind is the method that raw material is produced magnesium hydroxide crystal whisker with magnesite, the raw material that this method is used comprises that containing magnesium oxide reaches magnesite more than 45% by mass percent, certain density sulfuric acid, sodium hydroxide, it is characterized in that calcination magnesite obtained magnesium oxide in 3～6 hours under 600～700 ℃ of temperature, with this kind magnesium oxide is raw material, be mixed with concentration and be 1.0～10.0% magnesia magma, the add-on of aqueous sulfuric acid by magnesium oxide amount 1/4 mol ratio joined in the magnesia magma, then with in the magnesium oxide and the vitriolic mixing solutions thorough mixing and the autoclave of packing into that make, to being encased in the reaction soln warming while stirring of reactor, after a certain temperature in temperature reaches 130～180 ℃ of temperature ranges, constant temperature and pressure is incubated 2～6 hours down, water dilutes dispersion to the resultant alkali magnesium sulfate crystal whisker at normal temperatures then, washing and filtering, be raw material with it again, water is mixed with certain density alkali magnesium sulfate crystal whisker suspension, and be that 1: 1～1.6 ratio joins aqueous sodium hydroxide solution in the alkali magnesium sulfate crystal whisker suspension in the mole equivalent in the ratio of sodium hydroxide and alkali magnesium sulfate, again with warming while stirring in the autoclave of packing into behind the alkali magnesium sulfate crystal whisker that makes and the sodium hydroxide mixing solutions mixing, reach in predetermined 130～190 ℃ of temperature ranges after a certain temperature, constant temperature and pressure insulation 3～6 hours, stop heating then, cool to room temperature, take out the resultant of reaction magnesium hydroxide crystal whisker in the autoreaction still, washing and filtering is dried to finished product.
According to claim 1 said a kind of be the method that raw material is produced magnesium hydroxide crystal whisker with magnesite, it is characterized in that the certain mass concentration that said water in the method is mixed with in the alkali magnesium sulfate crystal whisker suspension of certain mass concentration is 1～5%.
According to claim 1 said a kind of be the method that raw material is produced magnesium hydroxide crystal whisker with magnesite, it is characterized in that in the method saidly with warming while stirring in the autoclave of packing into behind the alkali magnesium sulfate crystal whisker that makes and the sodium hydroxide mixing solutions mixing, its stirring intensity is 100～400rpm.
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Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101857258B (en) * | 2010-06-03 | 2012-11-14 | 东北大学 | Method for preparing light calcium carbonate and magnesium hydroxide from magnesium tailings |
| CN103523808A (en) * | 2013-09-27 | 2014-01-22 | 中盐制盐工程技术研究院 | Method for producing chloride-free magnesium hydroxide flame retardant from magnesia |
| CN103849924B (en) * | 2014-02-12 | 2016-06-29 | 沈阳理工大学 | A kind of method utilizing alkali magnesium sulfate crystal whisker to prepare nano-sized magnesium hydroxide whisker |
| CN104073870A (en) * | 2014-06-20 | 2014-10-01 | 沈阳理工大学 | Method for preparing submicron basic magnesium sulfate whisker with magnesite and prepared products |
| CN104153002A (en) * | 2014-08-22 | 2014-11-19 | 瓮福（集团）有限责任公司 | Method for preparing magnesium hydroxide crystal whiskers by utilizing magnesium-containing waste liquid |
| CN107641184A (en) * | 2017-09-25 | 2018-01-30 | 常州新区金利宝塑料制品有限公司 | A kind of preparation method of thermostable phenolic resin bonding agent |
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| CN1458066A (en) * | 2002-05-17 | 2003-11-26 | 隗学礼 | Process for preparing magnesium hydroxide whisker |
| CN1536102A (en) * | 2003-04-10 | 2004-10-13 | 大连晶须材料有限公司 | Method for synthesizing magnesium salt whiskers |
| CN1482287A (en) * | 2003-04-15 | 2004-03-17 | 清华大学 | New method of rapid synthesis of basic bitter salt |
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