CN104073870A - Method for preparing submicron basic magnesium sulfate whisker with magnesite and prepared products - Google Patents
Method for preparing submicron basic magnesium sulfate whisker with magnesite and prepared products Download PDFInfo
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- CN104073870A CN104073870A CN201410280167.8A CN201410280167A CN104073870A CN 104073870 A CN104073870 A CN 104073870A CN 201410280167 A CN201410280167 A CN 201410280167A CN 104073870 A CN104073870 A CN 104073870A
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Abstract
The invention relates to a method for preparing submicron basic magnesium sulfate whisker with magnesite and prepared products. The method is characterized by comprising steps of preparing magnesium oxide (obtained through calcining magnesite) into active magnesium oxide powder, then adding distilled water to prepare a magnesium oxide initial slurry with initial concentration of 0.25-1.25mol/kg, adding 1.0mol/dm<3> sulfuric acid aqueous solution and an additive-polyacrylamide to the initial slurry so as to obtain a base material, putting the base material into a high pressure reactor, heating up while stirring, preserving heat for 1.0-5.0 hours at constant temperature and constant pressure when the temperature in the reactor reaches 150-200DEG C, then stopping heating and stirring, air cooling to room temperature, and carrying out conventional treatment on the product to obtain the submicron basic magnesium sulfate whisker, wherein the draw ratio of the whisker is greater than 100, the average diameter is 100-300nm, and the content of single whisker is over 90%.
Description
Technical field
This invention belongs to inorganic non-metallic technical field of powdered material preparation, is specially a kind of method and product that utilizes magnesite to prepare submicron order alkali magnesium sulfate crystal whisker.
Background technology
In recent years, Magnesium Chemical Materials receives much concern in fields such as automobile, papermaking, aerospace, wherein alkali magnesium sulfate crystal whisker join in the organic polymer material such as PVC, ABS, have fire-retardant, press down cigarette and the multiple effect such as gain in strength, be the inorganic functional material of a kind of high added value, high economic benefit.
At present preparation and the applied research to alkali magnesium sulfate crystal whisker has more report, but the phenomenon such as ubiquity diameter of whiskers is large, topographic profile is inhomogeneous, and surface can be high, and stable not on thermodynamics, therefore in preparation and fabrication process, very easily reunite; Meanwhile, alkali magnesium sulfate crystal whisker has stronger wetting ability, causes when with polymkeric substance or other Material cladding, poor with the consistency of matrix, affects the mechanical property of compound rear material.The pattern of visible alkali magnesium sulfate crystal whisker and dispersiveness are one of key factors affecting its concrete application.So it is little to prepare diameter, good dispersity, the alkali magnesium sulfate crystal whisker of pattern expansion is the key issue of being eager at present solution.Research shows, diameter is that the alkali magnesium sulfate crystal whisker of submicron order and good dispersity joins and in polymeric matrix, has better dispersiveness, whisker surface can be lower, can improve the consistency of whisker and polymeric matrix, the tensile strength of this type of whisker and the compound rear material of polymkeric substance and shock strength are all apparently higher than common alkali magnesium sulfate crystal whisker.Therefore, submicron order alkali magnesium sulfate crystal whisker application prospect is more extensive, has more researching value.
Summary of the invention
Object of the present invention, is to provide a kind of method and product that utilizes magnesite to prepare submicron order alkali magnesium sulfate crystal whisker.
The extra light calcined magnesia that this invention obtains taking calcined magnesite, as raw material, taking dilute sulphuric acid as precipitation agent, adopts hydrothermal method to prepare submicron order alkali magnesium sulfate crystal whisker.Through test of many times, finally invented the preparation method of submicron order alkali magnesium sulfate crystal whisker, with high, the single Whisker Content of product purity that a process for preparing be whisker sum 90%, whisker mean diameter 200nm left and right, length-to-diameter ratio > 100, whisker morphology be even.
For achieving the above object and adopt technical scheme be:
Utilize magnesite to prepare method and the product of submicron order alkali magnesium sulfate crystal whisker, comprise the steps:
(1) by magnesite at 600-800 DEG C of temperature lower calcination 2.0-5.0h, magnesite rate of decomposition is reached more than 98%, obtain product magnesium oxide MgO, and prepared magnesium oxide has greater activity, adopt chlorion method to detect it, MgO activity Δ n
cl->=10 mol/kg, are all crushed to magnesian granularity≤-74 μ m, make activated magnesia powder;
(2) the activated magnesia powder making taking step (1), as raw material, adds distilled water to be mixed with the initial slip of MgO, and initial pulp density is 0.25-1.25mol/kg;
(3) be 1.0mol/dm to adding concentration in the initial slurry being prepared into by step (2)
3aqueous sulfuric acid and polyacrylamide additives, make base-material, wherein the aqueous sulfuric acid add-on (taking molar ratio computing) of 1.0mol/L is MgO:H
2sO
4=2.0-5.0:1, polyacrylamide add-on is the 1.0-3.0% of MgO quality.
(4) base-material step (3) being mixed with is put into autoclave, stir with the mixing speed of 100-500/min on intensification limit, limit, heat-up rate is controlled within the scope of average 10-20 DEG C/min, in the time that reactor temperature reaches 150-200 DEG C, constant temperature and pressure insulation 1.0-5.0h, then stop heating and stir, air cooling is to room temperature, in autoreaction still, take out synthetic product, through conventional dispersion, washing, filtration and dry, obtain the alkali magnesium sulfate crystal whisker of submicron order (diameter of whiskers is 100-300nm).
The pattern of above-mentioned alkali magnesium sulfate crystal whisker is that length-to-diameter ratio > 100, mean diameter are 100-300nm, and single Whisker Content reaches more than 90%.
To further illustrating of technique scheme:
Create and prepare in the process of submicron order alkali magnesium sulfate crystal whisker implementing this invention, the significant parameter that affects product quality comprises the rate of decomposition of magnesite and MgO activity, the initial pulp density of MgO, MgO:H
2sO
4mol ratio, temperature of reaction, reaction times, the factors such as stirring velocity, auxiliary agent kind and add-on.
(1) rate of decomposition of magnesite and MgO activity.The rate of decomposition of magnesite and MgO activity have critical impact to the formation of alkali magnesium sulfate crystal whisker, wherein choose magnesian active Δ n
cl->=10.0 mol/kg, and the submicron order alkali magnesium sulfate crystal whisker that the MgO of rate of decomposition>=98% of magnesite prepares is more satisfactory.
(2) the initial pulp density of MgO.The initial pulp density of MgO affects solution degree of supersaturation in reaction system, and low degree of supersaturation is conducive to nucleus growth, and crystal nucleation speed reduces relatively, and high degree of supersaturation is conducive to crystal nucleation, and growth velocity reduces.In order to make whisker morphology and dispersiveness reach best, the initial pulp density of MgO that the present invention adopts is 0.25-1.25mol/kg.
(3) MgO:H
2sO
4mol ratio.In order to make the more expansion of pattern of synthetic alkali magnesium sulfate crystal whisker, output is higher, should be by MgO:H
2sO
4mol ratio control within the specific limits, the two mol ratio is too low can not form whisker, when too high form diameter of whiskers thick, clustering phenomena is obvious.In order to make whisker reach best pattern, the MgO:H that the present invention adopts
2sO
4mol ratio should be controlled at 2.0-5.0:1.
(4) auxiliary agent kind and add-on.Add pattern and the dispersiveness to alkali magnesium sulfate crystal whisker of auxiliary agent play a part crucial.In preparation process, pass through to add auxiliary agent, the crystal face energy of non-growth crystal face in the nucleation of control nucleus and core growth process, make its oriented growth, and in core growth process, plane of crystal is coated to the surface polarity that reduces whisker, thereby control the clustering phenomena of whisker.Adopting polyacrylamide as dispersing auxiliary, is the 1-3%(wt of MgO quality in preparation process add-on), the alkali magnesium sulfate crystal whisker diameter of synthesized is 100-300nm, pattern expansion, good dispersity, single Whisker Content obviously increases.
(5) temperature of reaction.In alkali magnesium sulfate crystal whisker preparation process, temperature of reaction should be strict controlled in certain limit, the too low formation that is unfavorable for whisker of temperature, and excess Temperature affects whisker dispersiveness, has also caused the waste of the energy simultaneously.The alkali magnesium sulfate crystal whisker pattern that in the present invention, temperature of reaction obtains in the time of 150-200 DEG C is more satisfactory, and length-to-diameter ratio is larger, and diameter of whiskers is thinner, and mean diameter is 200nm left and right, and the expansion of whisker is better, and tiny Whisker Content is relatively low.
(6) reaction times.All there is direct impact the hydro-thermal reaction time on synthetic product pattern and thing phase composite.The hydro-thermal reaction time can not be too short, and the formation of whisker needs the sufficient reaction times, but the expansion of reaction times long whisker product pattern can decrease, diameter of whiskers chap, and agglomeration is obvious.At 150-200 DEG C, in the time that the reaction times is 1-5h, whisker morphology is more satisfactory, and length-to-diameter ratio is larger, whisker expansion.Utilize x-ray diffractometer to carry out phase structure analysis to synthetic product, result shows, the wire side spacing d value at the X-ray diffraction peak of synthesized product and the Mg of JCPDS7-415
6(OH) 10SO
43H
2the d value of O standard card is corresponding one by one, and peak shape is sharp-pointed, and inclusion-free peak exists, and illustrates that reaction product is all 153 type alkali magnesium sulfate crystal whiskers of complete crystallization.
(7) stirring velocity.In order to make, in hydrothermal reaction process, pulp density is even, temperature is consistent, will stir all the time for the MgO and the dilute sulphuric acid mixing solutions that join in reactor, and stirring velocity should be controlled within the specific limits.In the time that stirring velocity is 100-500r/min, can prepare the submicron order alkali magnesium sulfate crystal whisker of more satisfactory pattern.
This invention adopts S-3400N sem observation Hydrothermal Synthesis product pattern, is measured diameter and the length of fibrous product by SEM map analysis, calculates the length-to-diameter ratio of product; Characterize quantitatively the dispersiveness of whisker with single Whisker Content (single whisker quantity accounts for the per-cent of total whisker quantity); Utilize Ultima IV type x-ray diffractometer to detect the thing phase composite of synthetic product.
Compared with the existing technological method of preparing alkali magnesium sulfate crystal whisker, this invention tool has the following advantages:
(1) raw material sources are extensive.China is one of country that high-quality magnesite reserves are maximum.Taking it as raw material, can obviously reduce the preparation cost of alkali magnesium sulfate crystal whisker.
(2) technique is simple.Whole technological process is divided into four large operations, and the correlation parameter that each operation need to be controlled is fewer, simple to operate.
(3) production unit is more single.Stoving oven, autoclave and drying plant are the large main equipments of three in whole preparation technology, all the other large-scale hopper, mixing and whipping devices etc. that are acid and alkali-resistance, and therefore less investment, easily industrialization, and main equipment is easily realized automatically and being controlled.
(4) in the preparation process of sub-micron crystal whisker material, adopt the growth of additive control high preferred orientation, the coated whisker surface polarity that reduces in surface, thereby solve the rendezvous problem of submicron whisker, improve its dispersing property.
The submicron order alkali magnesium sulfate crystal whisker that utilizes present method to produce fills the domestic gaps, dose the consumption that both can reduce rubber, plastics in the high molecular polymer such as rubber, plastics, reduce goods cost, can significantly improve again the fire-retardant and mechanical mechanics property of material, reduce the probability of occurrence of fire failure, for society reduces unnecessary loss, improve people's sense of security and quality of life, realize environment-friendly flame retardant.
embodiment 1
Utilizing the magnesite that produce in Liaoning is raw material, prepares submicron order alkali magnesium sulfate crystal whisker.
(1) by magnesite 680 DEG C of temperature lower calcinations 3 hours, make magnesite rate of decomposition reach 98%, obtain product magnesium oxide MgO, and there is high reactivity, magnesian product granularity is all crushed to below-74 μ m, make activated magnesia powder;
(2) the activated magnesia powder making taking step (1), as raw material, adds distilled water to be mixed with the initial slip of MgO, and initial pulp density is 1.00mol/kg;
(3) be dilution heat of sulfuric acid and the polyacrylamide additive of 1.0mol/L to adding concentration in the initial slurry being prepared into by step (2), make base-material, wherein the dilution heat of sulfuric acid add-on of 1.0mol/L is pressed MgO:H with molar ratio computing
2sO
4the ratio of components of=3.0:1 adds, and polyacrylamide add-on is 2% of MgO quality;
(4) base-material step (3) being mixed with is put into autoclave, stir with the mixing speed of 500/min on intensification limit, limit, 10 DEG C/min of heat-up rate average out to, in the time that reactor temperature reaches 160 DEG C, constant temperature and pressure insulation 4.0h, then stops heating and stirs, air cooling is to room temperature, in autoreaction still, take out synthetic product, through conventional dispersion, washing, filtration and dry, obtain submicron order alkali magnesium sulfate crystal whisker.Molecular formula is MgSO
45Mg (OH)
23H
2o.
After testing, the alkali magnesium sulfate crystal whisker mean diameter obtaining is 200nm left and right, length-to-diameter ratio=112, single Whisker Content reaches 91%, smooth surface, straight, very thin, the main X-diffraction peak d value (descending) of synthetic product is respectively: 5.0925,3.8736,6.7941,1.9836,2.5932,2.2489,3.7985,2.9607,2,0061,2.6406,3.4037,2.4584,3.9553 and 1.5114, corresponding one by one with the d value of JCPDS7-415 alkali magnesium sulfate standard card, peak shape is sharp-pointed, and inclusion-free peak exists.Measurement results shows that Hydrothermal Synthesis product is submicron order (100-300nm) alkali magnesium sulfate crystal whisker, complete crystallization, and purity reaches 98.56%.
Claims (3)
1. utilize magnesite to prepare method and the product of submicron order alkali magnesium sulfate crystal whisker, it is characterized in that specifically comprising the steps:
(1) by magnesite at 600-800 DEG C of temperature lower calcination 2.0-5.0h, magnesite rate of decomposition is reached more than 98%, obtain product magnesium oxide MgO, magnesian granularity is all crushed to≤-74 μ m, make activated magnesia powder;
(2) the activated magnesia powder making taking step (1), as raw material, adds distilled water to be mixed with the initial slip of MgO, and initial pulp density is 0.25-1.25mol/kg;
(3) be 1.0mol/dm to adding concentration in the initial slurry being prepared into by step (2)
3aqueous sulfuric acid and polyacrylamide additives, make base-material, wherein the aqueous sulfuric acid add-on of 1.0mol/L is taking molar ratio computing as MgO:H
2sO
4=2.0-5.0:1, polyacrylamide add-on is the 1.0-3.0% of MgO quality;
(4) base-material step (3) being mixed with is put into autoclave, stir with the mixing speed of 100-500/min on intensification limit, limit, heat-up rate is controlled within the scope of average 10-20 DEG C/min, in the time that reactor temperature reaches 150-200 DEG C, constant temperature and pressure insulation 1.0-5.0h, then stops heating and stirs, and air cooling is to room temperature, in autoreaction still, take out synthetic product, after conventional processing, obtain submicron order alkali magnesium sulfate crystal whisker.
2. a kind of method of utilizing magnesite to prepare submicron order alkali magnesium sulfate crystal whisker according to claim 1, is characterized in that adopting chlorion method to detect the MgO activity making after calcining, MgO activity Δ ncl->=10 mol/kg.
3. the submicron order alkali magnesium sulfate crystal whisker that preparation method according to claim 1 obtains, the pattern that it is characterized in that whisker is that length-to-diameter ratio > 100, mean diameter are 100-300nm, single Whisker Content reaches more than 90%.
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104988576A (en) * | 2015-07-14 | 2015-10-21 | 中国科学院青海盐湖研究所 | Preparation method of basic magnesium sulfate whiskers |
| CN107201542A (en) * | 2017-06-08 | 2017-09-26 | 青海大学 | A kind of preparation method of alkali magnesium sulfate crystal whisker |
| CN110510644A (en) * | 2019-08-06 | 2019-11-29 | 东北大学 | A kind of active sub-micron method of magnesium oxide of fast pyrogenation magnesium sulfate preparation |
| CN111892072A (en) * | 2020-08-05 | 2020-11-06 | 辽宁辰昊镁业有限公司 | Method for preparing magnesium sulfate from magnesite tailings |
Citations (1)
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| CN1884633A (en) * | 2006-05-31 | 2006-12-27 | 东北大学 | Method for magnesium hydroxide whisker using giobertite as material |
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2014
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Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1884633A (en) * | 2006-05-31 | 2006-12-27 | 东北大学 | Method for magnesium hydroxide whisker using giobertite as material |
Non-Patent Citations (1)
| Title |
|---|
| 张丽丽: "单分散碱式硫酸镁晶须的制备及分散性研究", 《中国优秀硕士学位论文全文数据库 工程科技I辑》 * |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104988576A (en) * | 2015-07-14 | 2015-10-21 | 中国科学院青海盐湖研究所 | Preparation method of basic magnesium sulfate whiskers |
| CN104988576B (en) * | 2015-07-14 | 2018-01-16 | 中国科学院青海盐湖研究所 | The preparation method of alkali magnesium sulfate crystal whisker |
| CN107201542A (en) * | 2017-06-08 | 2017-09-26 | 青海大学 | A kind of preparation method of alkali magnesium sulfate crystal whisker |
| CN110510644A (en) * | 2019-08-06 | 2019-11-29 | 东北大学 | A kind of active sub-micron method of magnesium oxide of fast pyrogenation magnesium sulfate preparation |
| CN111892072A (en) * | 2020-08-05 | 2020-11-06 | 辽宁辰昊镁业有限公司 | Method for preparing magnesium sulfate from magnesite tailings |
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