CN114956134A - Co-production process of high-purity magnesium hydroxide and nitrogen potassium fertilizer - Google Patents
Co-production process of high-purity magnesium hydroxide and nitrogen potassium fertilizer Download PDFInfo
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- CN114956134A CN114956134A CN202210753756.8A CN202210753756A CN114956134A CN 114956134 A CN114956134 A CN 114956134A CN 202210753756 A CN202210753756 A CN 202210753756A CN 114956134 A CN114956134 A CN 114956134A
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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
- C01F5/20—Magnesium hydroxide by precipitation from solutions of magnesium salts with ammonia
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01C—AMMONIA; CYANOGEN; COMPOUNDS THEREOF
- C01C1/00—Ammonia; Compounds thereof
- C01C1/16—Halides of ammonium
- C01C1/164—Ammonium chloride
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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
- C01F5/145—Purification
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- C—CHEMISTRY; METALLURGY
- C05—FERTILISERS; MANUFACTURE THEREOF
- C05C—NITROGENOUS FERTILISERS
- C05C3/00—Fertilisers containing other salts of ammonia or ammonia itself, e.g. gas liquor
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- C—CHEMISTRY; METALLURGY
- C05—FERTILISERS; MANUFACTURE THEREOF
- C05D—INORGANIC FERTILISERS NOT COVERED BY SUBCLASSES C05B, C05C; FERTILISERS PRODUCING CARBON DIOXIDE
- C05D1/00—Fertilisers containing potassium
- C05D1/02—Manufacture from potassium chloride or sulfate or double or mixed salts thereof
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/80—Compositional purity
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/30—Hydrogen technology
- Y02E60/36—Hydrogen production from non-carbon containing sources, e.g. by water electrolysis
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Abstract
The invention discloses a co-production process of high-purity magnesium hydroxide and a nitrogen potassium fertilizer, which comprises the steps of taking waste liquid containing magnesium chloride and potassium chloride as a raw material, firstly adding an ammonia water precipitator to generate magnesium hydroxide precipitate, separating to obtain the nitrogen potassium fertilizer, preparing a magnesium hydroxide filter cake, sodium hypochlorite and water into mixed slurry, and carrying out hydrothermal treatment to obtain the high-purity magnesium hydroxide. The invention has the advantages of simple process, easy control of reaction, high purity of magnesium hydroxide products and the like.
Description
Technical Field
The invention belongs to the field of inorganic chemical product manufacturing, and particularly relates to a process method for co-producing high-purity magnesium hydroxide and a nitrogen-potassium fertilizer.
Background
Magnesium hydroxide is an important chemical product and intermediate, and has wide application and requirements in the industries of environmental protection, medicine, food, agriculture, chemical industry, petrifaction, electronics, heat-insulating refractory materials and the like. In particular, magnesium hydroxide material is a very important halogen-free flame retardant material, especially high-purity magnesium hydroxide, and the market value is very high. There are various methods for preparing magnesium hydroxide, which are mainly classified into a physical synthesis method and a chemical synthesis method. The physical synthesis method has high requirements on preparation equipment, high production cost and difficult popularization. The chemical synthesis method is simple and convenient and becomes an important way for producing the magnesium hydroxide.
At present, nitric acid and magnesium oxide are usedIn the technical process of producing the agricultural potassium nitrate by using the potassium chloride, a large amount of mother liquor waste containing magnesium chloride and potassium chloride is produced as a byproduct, and in order to reduce environmental pollution and change waste into valuable, the mother liquor waste can be used for producing high-purity magnesium hydroxide and nitrogen potassium fertilizer. It is known to add an alkaline precipitant to a magnesium salt solution to obtain a precipitate of magnesium hydroxide. However, the pH value of the solution of magnesium hydroxide at the isoelectric point is about 12, and when ammonia water is used as a precipitator to react with a magnesium chloride solution, the pH value of the solution is generally less than 12, so that magnesium hydroxide precipitates usually have positive charges, and chloride ions with negative charges are very easy to adsorb and enrich, so that the content of the chloride ions in the product exceeds the standard, and the purity of the magnesium hydroxide is reduced. Therefore, a new process which is simple to develop and operate, easy to industrialize and capable of effectively eliminating chloride ion impurities is developed to realize the purpose of preparing the bittern (MgCl) which is a salt production byproduct 2 ·6H 2 O) and other magnesium-containing substances are used as a magnesium source to prepare a high-purity magnesium hydroxide product, and the method has important economic and social benefits.
Disclosure of Invention
Aiming at the problems of low purity, high preparation cost and the like of products prepared by preparing magnesium hydroxide in the prior art, the invention provides an effective method for co-producing high-purity magnesium hydroxide and nitrogen-potassium fertilizer, and the method has the advantages of simple process and low preparation cost.
In order to solve the technical problems, the invention adopts the following technical scheme:
the invention provides a co-production process of high-purity magnesium hydroxide and a nitrogen potassium fertilizer, which comprises the following steps:
step 1: adding a mixed solution containing magnesium chloride and potassium chloride into a precipitation reactor at room temperature, and adding an ammonia water precipitator; fully mixing the mixed solution with an ammonia water precipitator under the stirring state to perform precipitation reaction shown in the formula (1), and then filtering the reaction mixture to obtain a magnesium hydroxide filter cake and a mother liquor containing ammonium chloride and potassium chloride;
evaporating, concentrating, cooling, crystallizing and separating the mother liquor to obtain a nitrogen-potassium fertilizer;
step 2: washing the magnesium hydroxide filter cake with water, mixing the washed magnesium hydroxide filter cake with sodium hypochlorite and water, and uniformly stirring to obtain mixed slurry; then, transferring the mixed slurry into a hydrothermal reaction kettle, sealing the hydrothermal reaction kettle, heating the hydrothermal reaction kettle, and carrying out hydrothermal oxidation-reduction reaction as shown in a formula (2); after the reaction is finished, cooling and filtering the reaction mixture, and washing and drying a filter cake to obtain a magnesium hydroxide product;
further, in the step 1, the mass fraction of magnesium chloride in the mixed solution containing magnesium chloride and potassium chloride is 5-20%, the mass fraction of ammonia in the ammonia water precipitator is 5-20%, and the molar ratio of magnesium chloride to ammonia when the mixed solution is mixed with the ammonia water precipitator is 1: 3-6.
Further, in the step 2, the mass fraction of magnesium hydroxide and the mass fraction of sodium hypochlorite in the mixed slurry are respectively 10% -40% and 0.05% -0.2%.
Further, in the step 2, the temperature of the hydrothermal oxidation-reduction reaction is 140-220 ℃ and the time is 2-6 hours.
Further, in step 2, the cake was washed with tap water 2 times and dried under vacuum at 90 ℃ for 8 hours.
The invention has the beneficial effects that:
1. the method utilizes the waste liquid containing magnesium chloride and potassium chloride, which is a byproduct in the preparation of potassium nitrate from nitric acid, magnesium oxide and potassium chloride, as the raw material, and simultaneously obtains the high-purity magnesium hydroxide and the nitrogen-potassium fertilizer through a simple process, and has the advantages of simple operation, easy reaction control and easy industrial production.
2. The invention converts chloride ions into neutral chloride molecules and leaves magnesium hydroxide by a hydrothermal reaction purification technology and utilizing an oxidation-reduction reaction, thereby eliminating chloride ion impurities in the magnesium hydroxide product, and the product has high purity, and the content of magnesium hydroxide is not less than 99.5 percent.
Drawings
FIG. 1 is a process flow diagram of the present invention for co-production of high purity magnesium hydroxide and nitrogen potassium fertilizer;
FIG. 2 is an XRD pattern of the high purity magnesium hydroxide prepared in examples 1-3.
Detailed Description
The following detailed description of embodiments of the invention refers to the accompanying drawings. The following is merely exemplary and illustrative of the inventive concept and various modifications, additions and substitutions of similar embodiments may be made by those skilled in the art without departing from the inventive concept or scope as defined in the accompanying claims.
Example 1
Adding a magnesium chloride potassium chloride mixed solution with the mass fraction of magnesium chloride of 10% and an ammonia water precipitator with the mass fraction of ammonia of 10% into a precipitation reactor at the same time according to the molar ratio of magnesium chloride to ammonia of 1:4 at room temperature, and stirring for reaction for 1 hour. The reaction mixture was then filtered to obtain a magnesium hydroxide filter cake and a mother liquor containing ammonium chloride and potassium chloride. And evaporating, concentrating, cooling, crystallizing and separating the mother liquor to obtain the nitrogen-potassium fertilizer.
Washing the magnesium hydroxide filter cake with water, mixing the washed magnesium hydroxide filter cake, sodium hypochlorite and water according to a certain proportion, and uniformly stirring to obtain mixed slurry with the mass fraction of the magnesium hydroxide being 20% and the mass fraction of the sodium hypochlorite being 0.15%. And then, transferring the mixed slurry into a hydrothermal reaction kettle, sealing the hydrothermal reaction kettle, heating the hydrothermal reaction kettle, carrying out hydrothermal reaction at 140 ℃, cooling and filtering the reaction mixture after 4 hours of reaction, and washing and drying a filter cake to obtain a magnesium hydroxide product. The product is analyzed according to HG/T3607-2007 standard, and the content of the magnesium hydroxide is 99.5 percent.
Example 2
Adding a magnesium chloride potassium chloride mixed solution with the mass fraction of magnesium chloride of 10% and an ammonia water precipitator with the mass fraction of ammonia of 10% into a precipitation reactor at the same time according to the molar ratio of magnesium chloride to ammonia of 1:4 at room temperature, and stirring for reaction for 1 hour. The reaction mixture was then filtered to obtain a magnesium hydroxide filter cake and a mother liquor containing ammonium chloride and potassium chloride. And evaporating, concentrating, cooling, crystallizing and separating the mother liquor to obtain the nitrogen-potassium fertilizer.
Washing the magnesium hydroxide filter cake with water, mixing the washed magnesium hydroxide filter cake, sodium hypochlorite and water according to a certain proportion, and uniformly stirring to obtain mixed slurry with the mass fraction of the magnesium hydroxide being 20% and the mass fraction of the sodium hypochlorite being 0.15%. And then, transferring the mixed slurry into a hydrothermal reaction kettle, sealing the hydrothermal reaction kettle, heating the hydrothermal reaction kettle, carrying out hydrothermal reaction at 180 ℃, cooling and filtering the reaction mixture after 4 hours of reaction, and washing and drying the filter cake to obtain a magnesium hydroxide product. The product is analyzed according to HG/T3607-2007 standard, and the content of the magnesium hydroxide is 99.6 percent.
Example 3
Adding a magnesium chloride potassium chloride mixed solution with the mass fraction of magnesium chloride of 10% and an ammonia water precipitator with the mass fraction of ammonia of 10% into a precipitation reactor at the same time according to the molar ratio of magnesium chloride to ammonia of 1:4 at room temperature, and stirring for reaction for 1 hour. The reaction mixture was then filtered to obtain a magnesium hydroxide filter cake and a mother liquor containing ammonium chloride and potassium chloride. And evaporating, concentrating, cooling, crystallizing and separating the mother liquor to obtain the nitrogen-potassium fertilizer.
Washing the magnesium hydroxide filter cake with water, mixing the washed magnesium hydroxide filter cake, sodium hypochlorite and water according to a certain proportion, and uniformly stirring to obtain mixed slurry with the mass fraction of the magnesium hydroxide being 20% and the mass fraction of the sodium hypochlorite being 0.15%. And then, transferring the mixed slurry into a hydrothermal reaction kettle, sealing the hydrothermal reaction kettle, heating the hydrothermal reaction kettle, carrying out hydrothermal reaction at 220 ℃, cooling and filtering the reaction mixture after 4 hours of reaction, and washing and drying a filter cake to obtain a magnesium hydroxide product. The product is analyzed according to HG/T3607-2007 standard, and the content of the magnesium hydroxide is 99.7 percent.
Example 4
Adding a magnesium chloride potassium chloride mixed solution with the mass fraction of magnesium chloride of 10% and an ammonia water precipitator with the mass fraction of ammonia of 10% into a precipitation reactor at the same time according to the molar ratio of magnesium chloride to ammonia of 1:4 at room temperature, and stirring for reaction for 1 hour. The reaction mixture was then filtered to obtain a magnesium hydroxide filter cake and a mother liquor containing ammonium chloride and potassium chloride. And evaporating, concentrating, cooling, crystallizing and separating the mother liquor to obtain the nitrogen-potassium fertilizer.
Washing the magnesium hydroxide filter cake with water, mixing the washed magnesium hydroxide filter cake, sodium hypochlorite and water according to a certain proportion, and uniformly stirring to obtain mixed slurry with the mass fraction of the magnesium hydroxide being 20% and the mass fraction of the sodium hypochlorite being 0.15%. And then, transferring the mixed slurry into a hydrothermal reaction kettle, sealing the hydrothermal reaction kettle, heating the hydrothermal reaction kettle, carrying out hydrothermal reaction at 180 ℃, cooling and filtering the reaction mixture after 2 hours of reaction, and washing and drying a filter cake to obtain a magnesium hydroxide product. The product is analyzed according to HG/T3607-2007 standard, and the content of the magnesium hydroxide is 99.5 percent.
Example 5
Adding a magnesium chloride potassium chloride mixed solution with the mass fraction of magnesium chloride of 10% and an ammonia water precipitator with the mass fraction of ammonia of 10% into a precipitation reactor at the same time according to the molar ratio of magnesium chloride to ammonia of 1:4 at room temperature, and stirring for reaction for 1 hour. The reaction mixture was then filtered to obtain a magnesium hydroxide filter cake and a mother liquor containing ammonium chloride and potassium chloride. And evaporating, concentrating, cooling, crystallizing and separating the mother liquor to obtain the nitrogen-potassium fertilizer.
Washing the magnesium hydroxide filter cake with water, mixing the washed magnesium hydroxide filter cake, sodium hypochlorite and water according to a certain proportion, and uniformly stirring to obtain mixed slurry with the mass fraction of the magnesium hydroxide being 20% and the mass fraction of the sodium hypochlorite being 0.15%. And then, transferring the mixed slurry into a hydrothermal reaction kettle, sealing the hydrothermal reaction kettle, heating the hydrothermal reaction kettle, carrying out hydrothermal reaction at 180 ℃, cooling and filtering the reaction mixture after 6 hours of reaction, and washing and drying the filter cake to obtain a magnesium hydroxide product. The product is analyzed according to HG/T3607-2007 standard, and the content of the magnesium hydroxide is 99.6 percent.
Example 6
Adding a magnesium chloride potassium chloride mixed solution with the mass fraction of magnesium chloride being 20% and an ammonia water precipitator with the mass fraction of ammonia being 20% into a precipitation reactor at the same time according to the molar ratio of magnesium chloride to ammonia being 1:4 at room temperature, and stirring and reacting for 1 hour. The reaction mixture was then filtered to obtain a magnesium hydroxide filter cake and a mother liquor containing ammonium chloride and potassium chloride. And evaporating, concentrating, cooling, crystallizing and separating the mother liquor to obtain the nitrogen-potassium fertilizer.
Washing the magnesium hydroxide filter cake with water, mixing the washed magnesium hydroxide filter cake, sodium hypochlorite and water according to a certain proportion, and uniformly stirring to obtain mixed slurry with the mass fraction of the magnesium hydroxide being 20% and the mass fraction of the sodium hypochlorite being 0.15%. And then, transferring the mixed slurry into a hydrothermal reaction kettle, sealing the hydrothermal reaction kettle, heating the hydrothermal reaction kettle, carrying out hydrothermal reaction at 180 ℃, cooling and filtering the reaction mixture after 4 hours of reaction, and washing and drying the filter cake to obtain a magnesium hydroxide product. The product is analyzed according to HG/T3607-2007 standard, and the content of the magnesium hydroxide is 99.5 percent.
Example 7
Adding a magnesium chloride potassium chloride mixed solution with the mass fraction of 5% of magnesium chloride and an ammonia water precipitator with the mass fraction of 5% of ammonia into a precipitation reactor at the same time according to the molar ratio of the magnesium chloride to the ammonia of 1:4 at room temperature, and stirring for reacting for 1 hour. The reaction mixture was then filtered to obtain a magnesium hydroxide filter cake and a mother liquor containing ammonium chloride and potassium chloride. And evaporating, concentrating, cooling, crystallizing and separating the mother liquor to obtain the nitrogen-potassium fertilizer.
Washing the magnesium hydroxide filter cake with water, mixing the washed magnesium hydroxide filter cake, sodium hypochlorite and water according to a certain proportion, and uniformly stirring to obtain mixed slurry with the mass fraction of the magnesium hydroxide being 20% and the mass fraction of the sodium hypochlorite being 0.15%. And then, transferring the mixed slurry into a hydrothermal reaction kettle, sealing the hydrothermal reaction kettle, heating the hydrothermal reaction kettle, carrying out hydrothermal reaction at 180 ℃, cooling and filtering the reaction mixture after 4 hours of reaction, and washing and drying the filter cake to obtain a magnesium hydroxide product. The product is analyzed according to HG/T3607-2007 standard, and the content of the magnesium hydroxide is 99.6 percent.
Example 8
Adding a magnesium chloride potassium chloride mixed solution with the mass fraction of magnesium chloride of 10% and an ammonia water precipitator with the mass fraction of ammonia of 10% into a precipitation reactor at the same time according to the molar ratio of magnesium chloride to ammonia of 1:6 at room temperature, and stirring for reacting for 1 hour. The reaction mixture was then filtered to obtain a magnesium hydroxide filter cake and a mother liquor containing ammonium chloride and potassium chloride. And evaporating, concentrating, cooling, crystallizing and separating the mother liquor to obtain the nitrogen-potassium fertilizer.
Washing the magnesium hydroxide filter cake with water, mixing the washed magnesium hydroxide filter cake, sodium hypochlorite and water according to a certain proportion, and uniformly stirring to obtain mixed slurry with the mass fraction of the magnesium hydroxide being 20% and the mass fraction of the sodium hypochlorite being 0.15%. And then, transferring the mixed slurry into a hydrothermal reaction kettle, sealing the hydrothermal reaction kettle, heating the hydrothermal reaction kettle, carrying out hydrothermal reaction at 180 ℃, cooling and filtering the reaction mixture after 4 hours of reaction, and washing and drying the filter cake to obtain a magnesium hydroxide product. The product is analyzed according to the HG/T3607-2007 standard, and the content of the magnesium hydroxide is 99.7 percent.
Example 9
Adding a magnesium chloride potassium chloride mixed solution with the mass fraction of magnesium chloride of 10% and an ammonia water precipitator with the mass fraction of ammonia of 10% into a precipitation reactor at the same time according to the molar ratio of magnesium chloride to ammonia of 1:3 at room temperature, and stirring for reaction for 1 hour. The reaction mixture was then filtered to obtain a magnesium hydroxide filter cake and a mother liquor containing ammonium chloride and potassium chloride. And evaporating, concentrating, cooling, crystallizing and separating the mother liquor to obtain the nitrogen-potassium fertilizer.
Washing the magnesium hydroxide filter cake with water, mixing the washed magnesium hydroxide filter cake, sodium hypochlorite and water according to a certain proportion, and uniformly stirring to obtain mixed slurry with the mass fraction of the magnesium hydroxide being 20% and the mass fraction of the sodium hypochlorite being 0.15%. And then, transferring the mixed slurry into a hydrothermal reaction kettle, sealing the hydrothermal reaction kettle, heating the hydrothermal reaction kettle, carrying out hydrothermal reaction at 180 ℃, cooling and filtering the reaction mixture after 4 hours of reaction, and washing and drying the filter cake to obtain a magnesium hydroxide product. The product is analyzed according to HG/T3607-2007 standard, and the content of the magnesium hydroxide is 99.5 percent.
Example 10
Adding a magnesium chloride potassium chloride mixed solution with the mass fraction of magnesium chloride of 10% and an ammonia water precipitator with the mass fraction of ammonia of 10% into a precipitation reactor at the same time according to the molar ratio of magnesium chloride to ammonia of 1:4 at room temperature, and stirring for reaction for 1 hour. The reaction mixture was then filtered to obtain a magnesium hydroxide filter cake and a mother liquor containing ammonium chloride and potassium chloride. And evaporating, concentrating, cooling, crystallizing and separating the mother liquor to obtain the nitrogen-potassium fertilizer.
Washing the magnesium hydroxide filter cake with water, mixing the washed magnesium hydroxide filter cake, sodium hypochlorite and water according to a certain proportion, and uniformly stirring to obtain mixed slurry with the mass fraction of the magnesium hydroxide being 20% and the mass fraction of the sodium hypochlorite being 0.05%. And then, transferring the mixed slurry into a hydrothermal reaction kettle, sealing the hydrothermal reaction kettle, heating the hydrothermal reaction kettle, carrying out hydrothermal reaction at 180 ℃, cooling and filtering the reaction mixture after 4 hours of reaction, and washing and drying the filter cake to obtain a magnesium hydroxide product. The product is analyzed according to HG/T3607-2007 standard, and the content of the magnesium hydroxide is 99.5 percent.
Example 11
Adding a magnesium chloride potassium chloride mixed solution with the mass fraction of magnesium chloride of 10% and an ammonia water precipitator with the mass fraction of ammonia of 10% into a precipitation reactor at the same time according to the molar ratio of magnesium chloride to ammonia of 1:4 at room temperature, and stirring for reaction for 1 hour. The reaction mixture was then filtered to obtain a magnesium hydroxide filter cake and a mother liquor containing ammonium chloride and potassium chloride. And evaporating, concentrating, cooling, crystallizing and separating the mother liquor to obtain the nitrogen-potassium fertilizer.
Washing the magnesium hydroxide filter cake with water, mixing the washed magnesium hydroxide filter cake, sodium hypochlorite and water according to a certain proportion, and uniformly stirring to obtain mixed slurry with the mass fraction of the magnesium hydroxide being 10% and the mass fraction of the sodium hypochlorite being 0.05%. And then, transferring the mixed slurry into a hydrothermal reaction kettle, sealing the hydrothermal reaction kettle, heating the hydrothermal reaction kettle, carrying out hydrothermal reaction at 180 ℃, cooling and filtering a reaction mixture after 4 hours of reaction, and washing and drying a filter cake to obtain a magnesium hydroxide product. The product is analyzed according to HG/T3607-2007 standard, and the content of the magnesium hydroxide is 99.7 percent.
Example 12
Adding a magnesium chloride potassium chloride mixed solution with the mass fraction of magnesium chloride of 10% and an ammonia water precipitator with the mass fraction of ammonia of 10% into a precipitation reactor at the same time according to the molar ratio of magnesium chloride to ammonia of 1:4 at room temperature, and stirring for reaction for 1 hour. The reaction mixture was then filtered to obtain a magnesium hydroxide filter cake and a mother liquor containing ammonium chloride and potassium chloride. And evaporating, concentrating, cooling, crystallizing and separating the mother liquor to obtain the nitrogen-potassium fertilizer.
Washing the magnesium hydroxide filter cake with water, mixing the washed magnesium hydroxide filter cake, sodium hypochlorite and water according to a certain proportion, and uniformly stirring to obtain mixed slurry with the mass fraction of the magnesium hydroxide being 40% and the mass fraction of the sodium hypochlorite being 0.2%. And then, transferring the mixed slurry into a hydrothermal reaction kettle, sealing the hydrothermal reaction kettle, heating the hydrothermal reaction kettle, carrying out hydrothermal reaction at 180 ℃, cooling and filtering the reaction mixture after 4 hours of reaction, and washing and drying the filter cake to obtain a magnesium hydroxide product. The product is analyzed according to HG/T3607-2007 standard, and the content of the magnesium hydroxide is 99.5%.
As can be seen from comparison of the results of analysis of the products obtained in examples 1 to 3, the purity of the magnesium hydroxide product slightly increased as the hydrothermal reaction temperature increased.
Comparing the results of the analyses of the products obtained in examples 2, 4 and 5, it is understood that the purity of the magnesium hydroxide product is slightly increased as the hydrothermal reaction time is increased.
Comparing the results of the analyses of the products obtained in examples 2, 6 and 7, it was found that the purity of the magnesium hydroxide product was lowered due to the excessive concentrations of the magnesium chloride and the ammonia water as the reaction raw materials.
Comparing the results of the analyses of the products obtained in examples 2, 8 and 9, it is understood that the purity of the magnesium hydroxide product slightly increases as the molar ratio of the ammonia water and the magnesium chloride, which are the reaction raw materials, increases.
Comparing the analysis results of the products prepared in the above examples 2, 10 to 12, it can be seen that the purity of the product magnesium hydroxide is slightly increased with the decrease of the mass fraction of magnesium hydroxide in the hydrothermal reaction mixed slurry, but the mass fraction of sodium hypochlorite in the mixed slurry has little influence on the purity of the product magnesium hydroxide within a certain range.
Comparing the results of the X-ray diffraction analysis of the products obtained in examples 1 to 3 above (see FIG. 2), it can be seen that the characteristic diffraction peak intensity of the product magnesium hydroxide slightly increases with the increase in the hydrothermal reaction temperature, indicating that the degree of crystallization of magnesium hydroxide slightly increases.
The present invention is not limited to the above exemplary embodiments, and any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (5)
1. A co-production process of high-purity magnesium hydroxide and nitrogen potassium fertilizer is characterized by comprising the following steps:
step 1: adding a mixed solution containing magnesium chloride and potassium chloride into a precipitation reactor at room temperature, and adding an ammonia water precipitator; fully mixing the mixed solution with an ammonia water precipitator under the stirring state to perform precipitation reaction shown in the formula (1), and then filtering the reaction mixture to obtain a magnesium hydroxide filter cake and a mother liquor containing ammonium chloride and potassium chloride;
evaporating, concentrating, cooling, crystallizing and separating the mother liquor to obtain a nitrogen-potassium fertilizer;
step 2: washing the magnesium hydroxide filter cake with water, mixing the washed magnesium hydroxide filter cake with sodium hypochlorite and water, and uniformly stirring to obtain mixed slurry; then, transferring the mixed slurry into a hydrothermal reaction kettle, sealing the hydrothermal reaction kettle, heating the hydrothermal reaction kettle, and carrying out hydrothermal oxidation-reduction reaction as shown in a formula (2); after the reaction is finished, cooling and filtering the reaction mixture, and washing and drying a filter cake to obtain a magnesium hydroxide product;
2. the co-production process according to claim 1, characterized in that: in the step 1, the mass fraction of magnesium chloride in the mixed solution containing magnesium chloride and potassium chloride is 5-20%, the mass fraction of ammonia in the ammonia water precipitator is 5-20%, and the molar ratio of magnesium chloride to ammonia when the mixed solution is mixed with the ammonia water precipitator is 1: 3-6.
3. The co-production process according to claim 1, characterized in that: in the step 2, the mass fraction of magnesium hydroxide and the mass fraction of sodium hypochlorite in the mixed slurry are respectively 10-40% and 0.05-0.2%.
4. The co-production process according to claim 1, characterized in that: in the step 2, the temperature of the hydrothermal oxidation-reduction reaction is 140-220 ℃ and the time is 2-6 hours.
5. The co-production process according to claim 1, characterized in that: in step 2, the filter cake is washed and dried by washing with water for 2 times and vacuum drying at 90 ℃ for 8 hours.
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4693872A (en) * | 1984-01-20 | 1987-09-15 | Asahi Glass Company Ltd. | Process for producing highly pure 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 |
| CN109721082A (en) * | 2019-03-22 | 2019-05-07 | 青海爱能森新材料科技有限公司 | A kind of production method of high purity magnesium hydroxide and potassium nitrate coproduction |
| CN111204779A (en) * | 2020-03-10 | 2020-05-29 | 余荣华 | Fused salt production method for co-producing high-purity magnesium hydroxide, magnesium carbonate and nitrogen-potassium fertilizer |
-
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- 2022-06-28 CN CN202210753756.8A patent/CN114956134A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4693872A (en) * | 1984-01-20 | 1987-09-15 | Asahi Glass Company Ltd. | Process for producing highly pure 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 |
| CN109721082A (en) * | 2019-03-22 | 2019-05-07 | 青海爱能森新材料科技有限公司 | A kind of production method of high purity magnesium hydroxide and potassium nitrate coproduction |
| CN111204779A (en) * | 2020-03-10 | 2020-05-29 | 余荣华 | Fused salt production method for co-producing high-purity magnesium hydroxide, magnesium carbonate and nitrogen-potassium fertilizer |
Non-Patent Citations (1)
| Title |
|---|
| 岳文虹等主编: "追寻化学教育的本源：化学疑难问题研究", 陕西科学技术出版社, pages: 345 * |
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