CN101214979A - Method for synthesizing active magnesium hydroxide - Google Patents
Method for synthesizing active magnesium hydroxide Download PDFInfo
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- CN101214979A CN101214979A CNA2008100557768A CN200810055776A CN101214979A CN 101214979 A CN101214979 A CN 101214979A CN A2008100557768 A CNA2008100557768 A CN A2008100557768A CN 200810055776 A CN200810055776 A CN 200810055776A CN 101214979 A CN101214979 A CN 101214979A
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- magnesium hydroxide
- mixed solution
- magnesia unslacked
- addition
- alkaline agent
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Abstract
The invention relates to a method for synthesizing active magnesium hydroxide, which employs cheap magnesite as raw material. Obtaining caustic calcined magnesite after calcining, and then neutralizing the caustic calcined magnesite with water under the circumstance of alkali agent or high-molecular agent to synthesize magnesium hydroxide with low viscosity, high activity, lastly concentration of the magnesium hydroxide reaches 35%.
Description
Technical field
The present invention relates to a kind of synthetic method of magnesium hydroxide, relate to a kind of method of using magnesite composite reactive magnesium hydroxide specifically.
Background technology
In order to prevent contaminate environment, in existing stack desulfurization and draining and in the technology, adopt limestone-based process, sodium hydroxide method, puritan filler magnesium method etc. usually.But all there is shortcoming in these methods, or accessory products is too many, or cost is too high.
Magnesia unslacked (MgO) is meant with magnesite to be raw material, under 750～1100 ℃ of temperature, behind reflecting kiln fluidizing furnace roast, the magnesium oxide powder that the process fine grinding forms, its steady quality, pure height, active good, can be widely used in industries such as refractory materials, chemical industry, building materials, papermaking and livestock industry.Magnesia unslacked is very high in the output of China, and as fertilizer sources etc. is widely used always.The main component of magnesite is MgCO
3, it also comprises Ca
2SiO
4H
2The Mg of O and trace
2SiO etc.
In magnesia unslacked, mainly comprise three kinds of materials, i.e. underburnt product, burning product and activated magnesia.Wherein, activated magnesia is a magnesia unslacked the inside The cream of the crop, mainly the content of requirement activated magnesia when being used for building material industry, if the active oxidation Mg content just can not fully reflect with the chlorion in the magnesium chloride inadequately, cause phenomenons such as anti-alkali, anti-halogen, violence occurring after the magnesite product moulding.
In addition, because magnesia unslacked has alkaline agent, so once attempted carrying out stack desulfurization with it.But magnesia unslacked is very bad as the response characteristic of alkaline agent, and it shows as: 1. do not dissolve in water; 2. very slow or the like with water reaction (slake reaction).Though many scientific research personnel make great efforts to attempt to change the response characteristic of magnesia unslacked, for example utilize and under heating condition, make magnesia unslacked and water reaction, but because the crystal structure of magnesia unslacked causes producing many solid sediments, thereby make this problem never be resolved.
Summary of the invention
The object of the present invention is to provide a kind of method for synthesizing active magnesium hydroxide, this method has overcome the one or more above-mentioned defective in the existing synthetic method basically, it adopts cheap magnesite is raw material, obtain magnesia unslacked through calcining, in the presence of alkaline agent or polymeric agent, carry out the slake reaction with water again, synthesize the low and active high magnesium hydroxide of viscosity.
The objective of the invention is to realize by the following technical solutions:
A kind of method for synthesizing active magnesium hydroxide comprises the steps:
1) with natural magnesite (MgCO
3) after 4～5 hours, be ground into fine particles 850 ℃～1000 ℃ calcinings, obtain magnesia unslacked (MgO);
2) stirring and dissolving in water with an amount of alkaline agent or polymeric agent, add an amount of magnesia unslacked thorough mixing that step 1) obtained then and form mixed solution, this mixed solution is heated to 60～100 ℃, stir, carry out slake reaction 20 minutes～5 hours, after the cooling, obtain high reactivity magnesium hydroxide solution.
Preferably, described alkaline agent is selected from NaOH, Ca (OH)
2, KOH and Na
2SiO
3In a kind of, its addition makes the pH of mixed solution greater than 10.5, preferred pH is greater than 12, or preferably by weight, the alkaline agent addition accounts for 1% of the mixed solution gross weight be made up of alkaline agent, magnesia unslacked and water.
Preferably, described polymeric agent is polycarboxylic acid's sodium or poly sodium acrylate, and its addition is greater than 0 and less than 0.2% with respect to the mixed solution gross weight of being made up of polymeric agent, magnesia unslacked and water by weight, preferred 0.1%.
Preferably, for the purpose of using and transporting, the addition of described magnesia unslacked by weight by make the concentration of acquisition magnesium hydroxide in mixed solution greater than 0 and less than 45%, preferred 35～45%.
Preferably, in order to improve water acidifying speed of response, described step 2) in the heating mixed solution temperature be higher than 80 ℃.For example, when beginning to carry out the slake reaction, can finish 90% reaction in 10～60 minutes at 95 ℃.
Preferably, described step 2) pH of mixed solution is greater than 12.
Preferably, the reaction times described step 2) is 1～3 hour.
The crystal structure of magnesia unslacked has determined its response characteristic, that is: 1. do not dissolve in water; 2. with water reaction slow (slake reaction) etc.
Although in the composition of magnesia unslacked the content of CaO greater than 1.5% and pH greater than 11 o'clock, crystal structure that can parallel off MgO, if but add highly basic agent such as NaOH again, mutual rejection can take place between the MgO particle, can prevent the goods precipitation, thus the better high reactivity magnesium hydroxide of building-up reactions., add NaOH and more can improve its activity less than 1.5% magnesia unslacked for CaO content, therefore, the inventor comes the crystal structure of parallel off magnesia unslacked with the method for raising hydroxide ion concentration.
Similarly, in magnesia unslacked, add polymeric agent, utilize mutual row's secondary response between the micropartical to prevent the precipitation of institute's synthetic magnesium hydroxide, also can obtain the effect identical, promptly obtain reactive strong and do not have a sedimentary magnesium hydroxide with adding alkaline agent.
The beneficial effect of the inventive method is: 1) will be difficult to make highly active magnesium hydroxide with the magnesia unslacked of water generation slake reaction, and can reaction fast take place efficiently with water; 2) concentration with the inventive method synthetic magnesium hydroxide solution can be concentrated to 45%, thereby is convenient to storage and reduces transportation cost; 3) traditional method of from seawater, refining magnesium hydroxide, the saltiness height of magnesium hydroxide solution, the corrosion machine, and synthetic magnesium hydroxide solution of the present invention saliferous not can not corrode machine; 4) the inventive method required equipment technology is simple, and equipment manufacturing cost is low.
The reaction of prepared magnesium hydroxide of the method according to this invention and SOx is fast, and the desulfuration efficiency height makes and unreacted magnesium hydroxide can not take place.When the neutralization reaction of carrying out acid effluent (pH 6～7), the time is fast, does not need excessive input, does not have the magnesium hydroxide residue.
Embodiment
More than be to general description the of the present invention, will be further explained the present invention by embodiment below.
Embodiment 1
With magnisite MgCO
3Under 850 ℃～1000 ℃ high temperature, calcined CO 4～5 hours
2After the evaporation, obtain magnesia unslacked (MgO).
Embodiment 2
To having 15m
3Add 10m in the reactive tank of the iron stirrer of reactive tank
3Water, with being steam heated to 50 ℃, stop steam then while stirring, add 150kg sodium hydroxide in reactive tank, at this moment, the pH of mixed solution is 10.5, treat to add the magnesia unslacked 4000kg that embodiment 1 prepares again after the fully dissolving, mix and stir after 20～30 minutes, when the temperature of reactive tank reaches 100 ℃, stop heating, natural reaction is 2～3 hours under this temperature, after reaction finishes, cooling, promptly obtain the magnesium hydroxide solution as product, its concentration is 35wt%, and yield is 100%.
Embodiment 3
To having 15m
3Add 10m in the reactive tank of the iron stirrer of reactive tank
3Water, with being steam heated to 50 ℃, stop steam then while stirring, add 200kg sodium hydroxide in reactive tank, fully dissolving back pH of mixed is 12, adds the magnesia unslacked 4000kg of embodiment 1 preparation then, mix and stir after 20～30 minutes, when the temperature of reactive tank reaches 80 ℃, stop heating, natural reaction is 2～3 hours under this temperature, after reaction finished, cooling promptly obtained the magnesium hydroxide solution as product, its concentration is 35 wt%, and yield is 100%.
Embodiment 4
To having 15m
3Add 10m in the reactive tank of the iron stirrer of reactive tank
3Water, with being steam heated to 50 ℃, stop steam then while stirring, in reactive tank, add 15kg poly sodium acrylate, treat to add the magnesia unslacked 4000kg that embodiment 1 prepares again after the fully dissolving, mix and stir after 20～30 minutes, when the temperature of reactive tank reaches 95 ℃, stop heating, natural reaction is 2～3 hours under this temperature, after reaction finishes, cooling, promptly obtain the magnesium hydroxide solution as product, its concentration is 35wt%, and yield is 100%.
Embodiment 5
To having 15m
3Add 10m in the reactive tank of the iron stirrer of reactive tank
3Water, with being steam heated to 50 ℃, stop steam then while stirring, in reactive tank, add 20kg polycarboxylic acid sodium, treat to add the magnesia unslacked 6000kg that embodiment 1 prepares again after the fully dissolving, mix and stir after 20～30 minutes, when the temperature of reactive tank reaches 60 ℃, stop heating, natural reaction is 2～3 hours under this temperature, after reaction finishes, cooling, promptly obtain the magnesium hydroxide solution as product, its concentration is 45wt%, and yield is 100%.
Embodiment 6
The commercially available magnesium hydroxide of four companies of selection is A as a comparative example, B, C, D, this magnesium hydroxide is and uses prior art with same method preparation, promptly uses seawater after decarbonate is handled to burn till product with Wingdale and carries out the slake reaction, obtains the magnesium hydroxide goods after concentrating, washing.Specification according to the magnesium hydroxide of the magnesium hydroxide of the embodiment of the invention 2 preparation and Comparative examples A is as shown in table 1.
Table 1
| Specification | The magnesium hydroxide (wt-%) of the embodiment of the invention 2 preparations | The magnesium hydroxide of Comparative examples A (wt-%) |
| Mg(OH) 2 | 96.95 | 95.2 |
| CaO | 1.46 | 1.10 |
| SiO 2 | 0.89 | 0.40 |
| Fe2O 3 | 0.42 | 0.10 |
| Al2O 3 | 0.14 | 0.20 |
Measure the various rerum naturas of the magnesium hydroxide of the prepared magnesium hydroxide of embodiment 2 and Comparative examples A～D respectively, it the results are shown in Table 2.
Table 2
| A | B | C | D | Embodiment 2 | |
| Concentration (weight %) | 32.6 | 30.1 | 32.6 | 31.8 | 32.5 |
| Viscosity (cps) | 3800 | 1410 | 930 | 1300 | 360 |
| Liquor ratio heavy (g/cc) | 1.22 | 1.21 | 1.23 | 1.22 | 1.23 |
| pH | 10.25 | 10.10 | 10.53 | 10.26 | 11.96 |
| Viscosity profile (um) 30 above 30-20 20-10 10-5 5-2 2-1 1 following average crystal grain granularities | 1.0 1.5 1.0 7.0 49.5 25.0 15.0 2.4 | 1.0 2.0 2.0 6.0 44.0 30.0 15.0 2.3 | 3.0 1.0 0.5 12.5 55.5 18.5 9.0 2.7 | 2.0 2.0 1.5 9.0 51.5 23.0 11.0 2.7 | 3.5 3.5 30.0 24.0 24.0 6.0 3.0 8.1 |
The synthetic magnesium hydroxide from seawater of A:A company;
The synthetic magnesium hydroxide from seawater of B:B company;
The synthetic magnesium hydroxide from seawater of C:C company;
The synthetic magnesium hydroxide from seawater of D:D company;
As can be seen from Table 2, the magnesium hydroxide quality in four comparative examples is unanimous on the whole.The magnesium hydroxide products viscosity of the inventive method preparation significantly reduces, thereby is convenient to transportation, reduces the freight.
Embodiment 7
Respectively 0.208mol is carried out neutralization reaction according to prepared magnesium hydroxide of embodiment 2～4 and magnesium hydroxide and the 2N sulfuric acid 0.2mol of Comparative examples A～D, assaying reaction speed respectively, it the results are shown in Table 3.
Table 3
| pH | 0.4 | 1.0 | 1.5 | 2.0 | 2.5 | 3.0 | 3.5 | 4.0 | 4.5 | 5.0 | 5.5 | 6.0 |
| Embodiment 2 | 0 | 11 | 15 | 25 | 31 | 34 | 38 | 43 | 52 | 69 | 95 | 124 |
| Embodiment 3 | 0 | 14 | 20 | 29 | 40 | 45 | 55 | 60 | 72 | 90 | 110 | 148 |
| Embodiment 4 | 0 | 13 | 16 | 26 | 33 | 37 | 39 | 46 | 56 | 75 | 100 | 135 |
| A | 0 | 13 | 40 | 74 | 90 | 136 | 170 | 185 | 256 | 330 | 395 | 514 |
| B | 0 | 6 | 14 | 26 | 38 | 50 | 58 | 84 | 135 | 193 | 244 | 347 |
| C | 0 | 3 | 7 | 11 | 15 | 23 | 36 | 57 | 173 | 930 | 1090 | 1326 |
| D | 0 | 3 | 10 | 16 | 39 | 56 | 105 | 160 | 164 | 170 | 190 | 219 |
Unit: second
As can be seen from Table 3, will carry out neutralization reaction, and only need 124～148 seconds just can make pH reach 6 according to the inventive method prepared magnesium hydroxide and sulfuric acid, and the above reaction times of the product needed twice among Comparative examples A～D.
Embodiment 8
Mensuration is by the precipitation threshold of the prepared magnesium hydroxide of embodiment 4, and it the results are shown in Table 4.
Table 4
| Date | Sedimentary state |
| Produce day | Soft, bulk, float on the upper strata |
| After 5 days | With the separated a little attitude of water, be identical with production day state but stir the back gently |
Utilize the method according to this invention, it is reactive good to have prepared, the high reactivity magnesium hydroxide that viscosity is low, and it is cheap, saves the labour, and storage is simple, and convenient transportation, the quality of item that is obtained are also apparently higher than the existing prepared product of technology.
Claims (10)
1. a method for synthesizing active magnesium hydroxide comprises the steps:
1) natural magnesite after 4～5 hours, is ground into fine particles 850 ℃～1000 ℃ calcinings, obtains magnesia unslacked;
2) stirring and dissolving in water with alkaline agent or polymeric agent, the magnesia unslacked that adds step 1) then and obtained forms mixed solution, and this mixed solution is heated to 60～100 ℃, stir, carry out slake reaction 20 minutes～5 hours, after the cooling, obtain the active hydrogen magnesium oxide solution.
2. method according to claim 1, wherein, described alkaline agent is selected from NaOH, Ca (OH)
2, KOH and Na
2SiO
3In any one, the addition of described alkaline agent makes the pH of mixed solution greater than 10.5.
3. method according to claim 2, wherein, the addition of described alkaline agent makes the pH of mixed solution greater than 12.
4. method according to claim 1, wherein, the addition of described alkaline agent accounts for 1% of the mixed solution gross weight be made up of alkaline agent, magnesia unslacked and water.
5. method according to claim 1, wherein, described polymeric agent is polycarboxylic acid's sodium or poly sodium acrylate, its addition by weight, with respect to the mixed solution gross weight of forming by polymeric agent, magnesia unslacked and water greater than 0 and less than 0.2%.
6. method according to claim 5, wherein, by weight, with respect to described mixed solution gross weight, the addition of described polymeric agent is 0.1%.
7. method according to claim 1, wherein, by weight, the addition of described magnesia unslacked by make the concentration of acquisition magnesium hydroxide in mixed solution greater than 0 and less than 45%.
8. method according to claim 7, wherein, by weight, the addition of described magnesia unslacked by make the concentration of acquisition magnesium hydroxide in mixed solution be 35～45%.
9. the temperature of mixed solution is higher than 80 ℃ method according to claim 1, wherein, described step 2).
10. the reaction times method according to claim 1, wherein, described step 2) is 1～3 hour.
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|---|---|---|---|
| CNA2008100557768A CN101214979A (en) | 2008-01-08 | 2008-01-08 | Method for synthesizing active magnesium hydroxide |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNA2008100557768A CN101214979A (en) | 2008-01-08 | 2008-01-08 | Method for synthesizing active magnesium hydroxide |
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ID=39621500
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2010004341A1 (en) * | 2008-07-10 | 2010-01-14 | Imerys Minerals Limited | Magnesium hydroxide |
| CN101804998A (en) * | 2010-04-19 | 2010-08-18 | 湘西自治州矿产与新材料技术创新服务中心 | Method for producing high-purity magnesium oxide by using dolomite |
| CN103115837A (en) * | 2013-01-05 | 2013-05-22 | 江苏博特新材料有限公司 | Method for testing content of magnesium oxide in magnesium oxide expanding agent |
| CN110642275A (en) * | 2019-11-05 | 2020-01-03 | 大连环球矿产股份有限公司 | Preparation method of magnesium hydroxide |
| CN114394611A (en) * | 2022-01-21 | 2022-04-26 | 洛阳中超新材料股份有限公司 | Preparation method of high-aspect-ratio flaky magnesium hydroxide |
-
2008
- 2008-01-08 CN CNA2008100557768A patent/CN101214979A/en active Pending
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2010004341A1 (en) * | 2008-07-10 | 2010-01-14 | Imerys Minerals Limited | Magnesium hydroxide |
| CN101804998A (en) * | 2010-04-19 | 2010-08-18 | 湘西自治州矿产与新材料技术创新服务中心 | Method for producing high-purity magnesium oxide by using dolomite |
| CN103115837A (en) * | 2013-01-05 | 2013-05-22 | 江苏博特新材料有限公司 | Method for testing content of magnesium oxide in magnesium oxide expanding agent |
| CN110642275A (en) * | 2019-11-05 | 2020-01-03 | 大连环球矿产股份有限公司 | Preparation method of magnesium hydroxide |
| CN114394611A (en) * | 2022-01-21 | 2022-04-26 | 洛阳中超新材料股份有限公司 | Preparation method of high-aspect-ratio flaky magnesium hydroxide |
| CN114394611B (en) * | 2022-01-21 | 2024-05-24 | 洛阳中超新材料股份有限公司 | Preparation method of high aspect ratio flaky magnesium hydroxide |
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Open date: 20080709 |