CN102674409B - Method for preparing rod-like magnesium hydroxide from salt lake brine - Google Patents
Method for preparing rod-like magnesium hydroxide from salt lake brine Download PDFInfo
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- CN102674409B CN102674409B CN2012101763608A CN201210176360A CN102674409B CN 102674409 B CN102674409 B CN 102674409B CN 2012101763608 A CN2012101763608 A CN 2012101763608A CN 201210176360 A CN201210176360 A CN 201210176360A CN 102674409 B CN102674409 B CN 102674409B
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Abstract
The invention discloses a method for preparing rod-like magnesium hydroxide from salt lake brine. The method comprises the following steps of: concentrating and crystallizing salt lake brine, from which elements such as potassium and lithium are extracted, serving as a raw material to obtain bischofite; dissolving the bischofite separated by crystallization into water to prepare magnesium chloride solution; introducing ammonia gas to perform magnesium precipitation reaction; when the pH value reaches 7-8, stopping introducing the ammonia gas, reacting at the temperature of 30-50 DEG C for 0.5-2 hours, aging and filtering to obtain alkaline magnesium chloride and magnesium precipitation mother liquor; dispersing the alkaline magnesium chloride in mixed solution of ethanol and water to obtain alkaline magnesium chloride suspension; adding sodium hydroxide to further precipitate to obtain rod-like magnesium hydroxide; filtering and separating to obtain magnesium precipitation mother liquor; replenishing the bischofite and circulating for precipitating the alkaline magnesium chloride; feeding to an ammonia still process along with concentration enrichment of magnesium precipitation mother liquor in ammonia chloride; performing ammonia still with lime; and circulating the produced ammonia gas to precipitate the alkaline magnesium chloride of a next batch and producing byproduct calcium chloride, wherein the magnesium content in the brine is not less than 93.4 g/L. The method has the advantages of high product purity, good economic benefit, no environmental pollution, high operability and easiness for industrial production.
Description
Technical field
The present invention relates to salt lake resources comprehensive utilization field, especially take salt lake brine as raw material, make the method for bar-shaped magnesium hydroxide.
Technical background:
China is a salt lake resources big country, and the resources such as potassium, sodium, magnesium are richly stored with in salt lake.Take the Qinghai East taigener salt-lake as example, the Repone K reserves that it has been established that reach 1,828 ten thousand tons, 8,400 ten thousand tons, sodium-chlor, 7,000 ten thousand tons, magnesium chloride.Potassium, sodium resources development and utilization are better, technology maturation, and the development and utilization of China's salt lake magnesium resource still is in the junior stage, and former material property product and low grade products are many, high-grade, the functionalization product is few, have formed the situation of low-end product outlet, high-end product import.
Magnesium hydroxide is as a kind of flame retardant products of environmental protection, has the multi-functionals such as fire-retardant, smoke elimination and filling, day by day is subject to people's favor.The pattern of magnesium hydroxide and size have a significant impact its application performance, and the magnesium hydroxide price of different-shape differs greatly.Than the hexagonal plate magnesium hydroxide fire retardant, fibrous magnesium hydroxide can strengthen the impact resistance of macromolecular material, has fire-retardant, reinforcement, toughness reinforcing in the characteristic of one.Needle-like or bar-shaped magnesium hydroxide can significantly improve the axial stress of filamentary material.In addition, bar-shaped magnesium hydroxide still prepares bar-shaped magnesian presoma, and bar-shaped magnesium oxide is a kind of high-end electronic product.Therefore the magnesium hydroxide that utilizes salt lake brine to prepare special appearance is the efficient approach that utilizes of magnesium resource, can widen the Application Areas of magnesium resource, improves the economic worth of magnesium resource.
Report about the preparation method of hexagonal plate magnesium hydroxide numerous, and bar-shaped magnesium hydroxide prepare bibliographical information seldom.Zhang Bo, take basic magnesium chloride as presoma, adopts hydrothermal method to prepare bar-shaped magnesium hydroxide, and this technique needs High Temperature High Pressure.Li Zhenxing is take magnesium chloride and sodium hydroxide as raw material, synthesizing flaky magnesium hydroxide at first, and then successively process and obtain bar-shaped magnesium hydroxide with magnesium chloride and sodium hydroxide solution respectively, this technique process is many, complicated operation, and cost is high.Wang Baohe, take bar-shaped basic magnesium chloride as raw material, utilizes polyoxyethylene glycol to prepare bar-shaped magnesium hydroxide for the template Direct precipitation, through calcining, obtains bar-shaped magnesium oxide; The dragon rising sun is take magnesium acetate as raw material, form 1-dimention nano micellar structure in the PVP/ ethylene glycol solution, and utilize the soft template of this micellar structure as nano-functional material, with the low temperature reflux method synthesized polycrystalline, than magnesium hydroxide nano thread and the nanometer rod of high length-diameter ratio.These process using tensio-active agents are done template, surfactant washing difficulty, residual meeting polluted product.
Summary of the invention:
The purpose of this invention is to provide a kind of method that is prepared bar-shaped magnesium hydroxide by salt lake brine, present method technique is simple, required process costs is low, production process need not added any tensio-active agent, whole technological process can effectively be avoided environmental pollution, has realized the comprehensive utilization of salt lake brine magnesium resource.
Technical scheme of the present invention is
Extract bittern after the elements such as potassium, lithium take salt lake as raw material, condensing crystal obtains bischofite, with the water-soluble magnesium chloride solution of making of the bischofite of crystallization, pass into ammonia and sink reactive magnesium, when the pH value reaches 7-8, stop passing into ammonia, in reaction under 30-50 ℃ after 0.5-2 hour, then ageing, filter and obtain basic magnesium chloride and heavy mother liquid of magnesium; Basic magnesium chloride is dispersed in the mixing solutions of ethanol and water and obtains basic magnesium chloride suspension, add sodium hydroxide further precipitation obtain bar-shaped magnesium hydroxide; Filtering separation obtains heavy mother liquid of magnesium, by adding bischofite, is cycled to used in the precipitation basic magnesium chloride, but along with the concentration enrichment of ammonium chloride in heavy mother liquid of magnesium, need deliver to ammonia still process, use lime ammonia still process, the ammonia recycle of generation is used for next batch precipitation basic magnesium chloride, and by-product calcium chloride;
Bittern Mg content of the present invention is not less than 93.4g/L.
Bischofite of the present invention is concentrated by salt lake brine, and primary crystallization obtains.(bischofite that is gained need not through purifying treatment, unlike some technique in prior art, need to use the recrystallization chloromagnesite of purifying waste water).
The present invention passes into ammonia and sinks in the reactive magnesium process, and ammonia: the mol ratio of magnesium is controlled to be 1:5 to 1:4.
The present invention passes into ammonia and sinks basic magnesium chloride reaction, and the concentration of described magnesium chloride solution is 3-5mol/L.
Ageing described in the present invention is static ageing 36-72 hour in 45-55 ℃ of water-bath.
During the ammonium chloride cumulative concentration of heavy mother liquid of magnesium 〉=218g/L, need be sent to ammonia still process.
The scope of described ethanol and water volume ratio is 3:1 to 10:1.
The concrete operation steps of the present invention is as follows:
1) will extract salt lake brine after potassium, sodium, lithium, its Mg content 93.4g/L, proportion 1.28g/mL, be 2.30g/mL at 118 ℃ of lower evaporation concentration to proportion, then is incubated 2-3 hour, filtered while hot, is cooled to room temperature, crystallization bischofite.
2) bischofite that step 1) is obtained is water-soluble, be made into the solution that density of magnesium chloride is 3-5mol/L, pass into ammonia and sink reactive magnesium under stirring, ammonia: the mol ratio of magnesium is controlled to be 1:5 to 1:4, when the pH value reaches 7-8, stop passing into ammoniacal liquor, reaction 0.5-2 hour under 30-50 ℃, then change static ageing 36-72 hour in 50 ℃ of water-baths over to, filter and obtain basic magnesium chloride and heavy mother liquid of magnesium.
3) mixing solutions of preparation ethanol and water, the volume ratio that makes ethanol and water is 3:1.
4) with step 2) basic magnesium chloride that obtains is dispersed in the mixing solutions of the ethanol of step 3) preparation and water, start and stir, drip 3mol/L NaOH solution, making basic magnesium chloride and sodium hydroxide mol ratio is 1:1.5, at 30-40 ℃ of reaction 1-2 hour, filtration, washing, oven dry obtain bar-shaped magnesium hydroxide.
5) with step 2) the heavy mother liquid of magnesium that obtains adds bischofite, being made into magnesium ion concentration is 3-5mol/L solution, turns back to step 2) in the precipitation basic magnesium chloride; When step 2) during the ammonium chloride concentration of the heavy mother liquid of magnesium that obtains 〉=218g/L, need be sent in the ammonia still process tank and use lime ammonia still process, the ammonia of generation turns back to step 2) in heavy magnesium, ammonia obtains recycle.
6) mother liquor after ammonia still process obtains the calcium chloride crystal through evaporation, concentrated, crystallization.
Advantage of the present invention and active effect are:
Raw material of the present invention is to produce the old halogen of discharging after potash fertilizer, the bittern after ion-exchange absorption lithium, and magnesium ion concentration reaches 93.4g/L, and proportion is 1.28g/mL, and raw material sources are extensive.The salt lake brine that employing is extracted after lithium obtains bischofite through concentrated, crystallisation by cooling, after ammonia process precipitation, ageing, bischofite changes bar-shaped basic magnesium chloride into, bar-shaped magnesium hydroxide with the further precipitation high added value of sodium hydroxide, what solved the salt lake brine magnesium resource efficiently utilizes problem, has improved the ecotope of potash fertilizer producing area.The particle of gained magnesium hydroxide is large, and strainability is good, and washing easily, is conducive to separation and the removal of impurity.The heavy mother liquid of magnesium that the present invention obtains, through circulation enrichment ammonium chloride, reclaims ammonia with lime ammonia still process method.Heavy magnesium rate of the present invention reaches more than 90%, and with the ammonium chloride in the cheap heavy mother liquid of magnesium of lime recovery, ammonia recycle, by-product calcium chloride, good in economic efficiency simultaneously, the production process non-environmental-pollution.
Description of drawings
For further understanding the present invention, below with embodiment, elaborate, provide in the following drawings and also to describe magnesium hydroxide that invention obtains and the feature of basic magnesium chloride, wherein:
Fig. 1 is process flow sheet of the present invention.
Fig. 2 is the X-ray diffraction spectrogram of basic magnesium chloride;
Fig. 3 is the scanning electron microscope (SEM) photograph of basic magnesium chloride;
Fig. 4 is the X-ray diffraction spectrogram of magnesium hydroxide;
Fig. 5 is the scanning electron microscope (SEM) photograph of magnesium hydroxide.
Embodiment:
Salt lake brine goes out vitriolate of tartar, sodium-chlor, Repone K through salt pan evaporation, condensing crystal, after the adsorbing and extracting lithium, obtains containing the old halogen bittern of magnesium and boron, and composition is in Table 1.
1) condensing crystal bischofite
Add 10L bittern in retort, 118 ℃ of heating are concentrated, when the bittern volume reduces to 6.5L, and stopped heating, filtered while hot after sealing thermal insulation 2-3 hour, be cooled to room temperature with filtrate, crystallization bischofite (composition is in Table 2), weight is 2.6kg.
2) ammonia process precipitation basic magnesium chloride
The bischofite that obtains is water-soluble, be made into the solution that magnesium ion concentration is 3.5mol/L, volume is 3.5L, be to add the 15L ammonium chloride mother liquor in the ammonia still process tank of 30L with volume, 3.8kg lime, heating, the ammonia that produces is passed in heavy magnesium tank, open and stir, when ammonia/when the magnesium ratio reached 1:5, the pH value was 7.8, stop passing into ammonia, 35 ℃ of lower stirring reactions 1.5 hours, then change in water-bath 50 ℃ of static ageings 48 hours, filter and obtain basic magnesium chloride 140g and heavy mother liquid of magnesium 2.45L (magnesium ion concentration 2.65mol/L).The x-ray diffraction pattern of basic magnesium chloride such as Fig. 2, scanning electron microscope such as Fig. 3.
3) heavy reactive magnesium
The mixing solutions 5.25L of preparation ethanol and water, the volume ratio that makes ethanol and water is 3:1.The 140g basic magnesium chloride is dispersed in the mixing solutions of ethanol and water, drips 3mol/L NaOH solution 263mL, making basic magnesium chloride and sodium hydroxide mol ratio is 1:1.5.35 ℃ were reacted 1 hour, and filtration, washing, oven dry obtain bar-shaped magnesium hydroxide 91.85g, its x-ray diffraction pattern such as Fig. 4, scanning electron microscope such as Fig. 5.
4) recycling of heavy mother liquid of magnesium
In step 2) in obtain heavy mother liquid of magnesium and add bischofite 1.17kg, being made into magnesium ion concentration is 3.5mol/L solution 3.5L, turns back to step 2) in the precipitation basic magnesium chloride.
While through the ammonium chloride concentration of 4 heavy mother liquid of magnesium of circulation, reaching 218g/L, no longer add bischofite, and directly be sent in the ammonia still process tank, use lime ammonia still process, the ammonia of generation is used for next batch and precipitates basic magnesium chloride.
5) reclaim byproduct calcium chloride
Mother liquor chloride containing calcium 50-60% after ammonia still process, after removal of impurities, produce byproduct calcium chloride with evaporation, method concentrated, crystallization after filtration.
The ICP-AES analytical results (mg/L) of table 1 salt lake brine
English in table please make Chinese into
Table 2 bischofite ICP-AES analytical results (ug/g)
Claims (7)
1. salt lake brine prepares the method for bar-shaped magnesium hydroxide, extract bittern after potassium, elemental lithium take salt lake as raw material, condensing crystal obtains bischofite, with the water-soluble magnesium chloride solution of making of the bischofite of crystallization, pass into ammonia and sink reactive magnesium, when the pH value reaches 7-8, stop passing into ammonia, in reaction under 30-50 ℃ after 0.5-2 hour, ageing again, filter and obtain basic magnesium chloride and heavy mother liquid of magnesium; Basic magnesium chloride is dispersed in the mixing solutions of ethanol and water and obtains basic magnesium chloride suspension, add sodium hydroxide further precipitation obtain bar-shaped magnesium hydroxide; Filtering separation obtains heavy mother liquid of magnesium, by adding bischofite, is cycled to used in the precipitation basic magnesium chloride, but along with the concentration enrichment of ammonium chloride in heavy mother liquid of magnesium, need deliver to ammonia still process, use lime ammonia still process, the ammonia recycle of generation is used for next batch precipitation basic magnesium chloride, and by-product calcium chloride; Described bittern Mg content is not less than 93.4g/L.
2. method according to claim 1, ammonia: the magnesium mol ratio is controlled to be 1:5 to 1:4.
3. method according to claim 2, the density of magnesium chloride that uses is 3-5mol/L.
4. according to claim 1-3 described methods of any one, described ageing is static ageing 36-72 hour in 45-55 ℃ of water-bath.
5. method according to claim 1, the solution that adopts is that ethanol and water volume ratio are the mixing solutions of 3:1-10:1.
6. method according to claim 1, the ammonium chloride cumulative concentration 〉=218g/L in heavy mother liquid of magnesium send ammonia still process.
7. salt lake brine prepares the method for bar-shaped magnesium hydroxide, comprises the steps:
1) salt lake brine goes out vitriolate of tartar, sodium-chlor, Repone K through salt pan evaporation, condensing crystal, after the adsorbing and extracting lithium, described bittern Mg content is not less than 93.4g/L, proportion 1.28g/mL, be 2.30g/mL at 118 ℃ of lower evaporation concentration to proportion, then, at 118 ℃ of insulation 2-3 hour, filtered while hot, filtrate is cooled to room temperature, crystallization bischofite;
2) bischofite of crystallization is water-soluble, be made into the solution that density of magnesium chloride is 3-5mol/L, passing into ammonia stirs and to sink reactive magnesium, ammonia: the mol ratio of magnesium is controlled to be 1:5 to 1:4, when the pH value reaches 7-8, stop passing into ammonia, reaction 0.5-2 hour under 30-50 ℃, then change static ageing 36-72 hour in 50 ℃ of water-baths over to, filter and obtain basic magnesium chloride and heavy mother liquid of magnesium;
3) mixing solutions of preparation ethanol and water, the volume ratio that makes ethanol and water is 3:1;
4) with step 2) basic magnesium chloride that obtains is dispersed in the mixing solutions of the ethanol of step 3) preparation and water, start and stir, drip 3mol/L NaOH solution, making basic magnesium chloride and sodium hydroxide mol ratio is 1:1.5, at 30-40 ℃ of reaction 1-2 hour, filtration, washing, oven dry obtain bar-shaped magnesium hydroxide;
5) with step 2) the heavy mother liquid of magnesium that obtains adds a certain amount of bischofite, being made into magnesium ion concentration is 3-5mol/L solution, turns back to step 2) in be used for the precipitation basic magnesium chloride; Send in the ammonia still process tank and use lime ammonia still process during the ammonium chloride concentration enrichment in the heavy mother liquid of magnesium step 2) 〉=218g/L, the ammonia of generation turns back to step 2) in heavy magnesium, ammonia obtains recycle;
6) through 5) mother liquor of step after ammonia still process obtain the calcium chloride crystal through evaporation, concentrated, crystallization.
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| CN103193254B (en) * | 2013-03-12 | 2014-12-03 | 广西大学 | Novel technology for simultaneously preparing rodlike and sheetlike nano-sized magnesium hydroxide |
| CN103626210A (en) * | 2013-12-13 | 2014-03-12 | 华东理工大学 | Method for preparing magnesium hydroxide and chlorine by coupling magnesium chloride reactive crystallization and electrolysis |
| CN104071813A (en) * | 2014-07-08 | 2014-10-01 | 中国科学院青海盐湖研究所 | Method for preparing magnesium hydroxide |
| CN104261442A (en) * | 2014-07-08 | 2015-01-07 | 云天化集团有限责任公司 | Method for preparing magnesium hydroxide |
| CN105060320A (en) * | 2015-07-23 | 2015-11-18 | 韦海棉 | Method for preparing magnesium hydroxide by high magnesium-lithium ratio salt lake brine |
| CN107515430B (en) * | 2017-06-06 | 2019-05-28 | 青岛大学 | A kind of method of seismic wave method detection salt lake bittern |
| CN107935002A (en) * | 2017-12-25 | 2018-04-20 | 岭南师范学院 | A kind of method that Basic magnesium bromide whisker is produced in bittern from dried-up lake |
| CN107935001A (en) * | 2017-12-25 | 2018-04-20 | 岭南师范学院 | A kind of method that alkali formula magnesium iodide whisker is produced in bittern from dried-up lake |
| CN115321565B (en) * | 2022-08-03 | 2023-10-13 | 国投新疆罗布泊钾盐有限责任公司 | Method for preparing nano magnesium hydroxide by taking salt lake brine as raw material |
| CN115448336B (en) * | 2022-09-20 | 2023-09-15 | 西安工程大学 | Precipitation-method superfine magnesium hydroxide material easy to filter and wash and preparation method thereof |
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| CN1837067A (en) * | 2005-03-25 | 2006-09-27 | 崔绍静 | Research for comprehensive utilization of seawater and brine comprising sea water desalination and soda preparation by saturated Brine |
| US7686986B2 (en) * | 2006-01-05 | 2010-03-30 | Headwaters Technology Innovation, Llc | Magnesium hydroxide nanoparticles, methods of making same and compositions incorporating same |
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