Preparation method of basic magnesium chloride

Abstract

The invention discloses a preparation method of basic magnesium chloride, which comprises the following steps: dissolving magnesium chloride in water, heating to 50-95 DEG C, and stirring for 1-2 hours to obtain a colorless and transparent first solution; magnesium oxide is added into the first solution, alkali is added to adjust the pH to be 8-10, heat preservation is conducted, stirring continues for 1-4 h, and a second solution is obtained; pulping the second solution into a crystallization kettle, crystallizing, centrifuging, washing, drying a filter cake at 80-105 DEG C to obtain a white product basic magnesium chloride, and circulating mother liquor water for the synthesis reaction. The synthesis process provided by the invention is simple, high in product yield and yield and suitable for mass production, a common chemical synthesis kettle can meet production requirements, high-temperature and high-pressure procedures are avoided, and the production cost is reduced. The method is low in energy consumption, high in safety, free of wastewater and sewage discharge, green and environment-friendly.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical synthesis, and in particular relates to a method for preparing basic magnesium chloride. Background Art

[0002] Magnesium accounts for about 0.05% of the body weight in animals. It is a macronutrient and is mainly concentrated in mitochondria. It is particularly important for maintaining the biological activity of many enzyme systems, especially those related to oxidative phosphorylation. It can regulate nerve conduction and muscle contraction, promote calcium absorption and metabolism, stabilize myocardial cell membranes, and promote normal heart rhythm. Magnesium is also an activating factor for many enzymes, participates in a variety of enzymatic reactions in the body and regulates oxidative stress, and is essential for maintaining the energy level of animals. Therefore, in animal feeding and feed formulation, appropriate intake of magnesium should be ensured to meet the physiological needs of animals.

[0003] Basic magnesium chloride can be used as a new type of basic salt feed additive. Basic magnesium chloride has a variety of crystal configurations, and the three most common ones are Mg2(OH)3Cl, Mg2(OH)3Cl·4H2O, and Mg3(OH)5Cl·4H2O. The general formula is Mg(OH)Cl or [Mg(OH)2]x·[MgCl2]y·nH2O.

[0004] At present, there are no large-scale basic magnesium chloride products on the market. According to literature reports, the synthesis technology of basic magnesium chloride is mainly divided into three categories. The first category is to use refined hydrochloric acid stone with a mass fraction of not less than 45%, pyrolyze at 350-360℃, and prepare basic magnesium chloride by strictly controlling the pyrolysis temperature, time and moisture content in the air; the second category is to adjust the pH of the aqueous solution of magnesium chloride and calcium chloride to 8-9 by calcium hydroxide / sodium hydroxide / sodium bicarbonate / sodium carbonate, and then smelt at 50-90℃, and then age for 2-4 days. The crude product is washed and dried to obtain basic magnesium chloride; the third category is hydrothermal synthesis at 150-180℃, and then aged, washed and dried to prepare basic magnesium chloride products. Among them, the first and third categories require high temperature and pressure-resistant equipment, the synthesis time is long, and high temperature and high pressure have strict safety requirements. The second category introduces a large amount of non-magnesium metal elements, there are many by-products, and it is difficult to handle. Summary of the invention

[0005] The main purpose of the invention is to provide a preparation method of basic magnesium chloride, which has simple synthesis process, high product output and yield, is suitable for mass production, a general chemical synthesis kettle can meet the production requirements, has no high temperature and high pressure process, has low energy consumption, high safety, no wastewater and sewage discharge, and is green and environmentally friendly.

[0006] In order to achieve the purpose of the present invention, the present invention provides a preparation method of basic magnesium chloride. The method comprises the following steps: firstly dissolving magnesium chloride in water, heating the solution to 50-95°C, and stirring the solution for 1-2 hours to obtain a colorless and transparent first solution; adding magnesium oxide to the first solution, adding alkali to adjust the pH value to 8-10, and keeping the solution warm and stirring the solution for 1-4 hours to obtain a second solution; slurrying the second solution into a crystallization kettle, crystallizing, centrifuging, and washing the solution with water, and drying the filter cake at 80-105°C to obtain a white product, basic magnesium chloride, and the mother liquor water circulation sleeve is used for the above-mentioned synthesis reaction.

[0007] In a possible implementation, the magnesium chloride is at least one of anhydrous magnesium chloride and magnesium chloride hexahydrate with a purity of more than 90%.

[0008] In a possible implementation manner, the mass concentration of the first solution is 10-60%.

[0009] In a possible embodiment, the magnesium oxide has a purity of more than 90% and a density of 2.8-3.6 g / cm 3 .

[0010] In a possible implementation, the base is at least one of sodium bicarbonate, sodium carbonate, sodium hydroxide, and calcium hydroxide.

[0011] In a possible implementation, the molar ratio of the magnesium chloride to the magnesium oxide is 1:(2-6).

[0012] The present invention has achieved the following beneficial effects:

[0013] 1. The synthesis process is simple, the reaction time is short, the product output and yield are high, and it is suitable for mass production

[0014] 2. General chemical synthesis kettle can meet production requirements, no high temperature and high pressure process, low energy consumption and high safety

[0015] 3. No organic solvent is used, the mother liquor can be recycled, no wastewater or sewage is discharged, and it is green and environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is the XRD diffraction pattern of Example 2. DETAILED DESCRIPTION

[0017] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0018] The purpose of the present invention is to solve the above-mentioned synthesis technology defects of basic magnesium chloride and invent a preparation method of basic magnesium chloride. The corresponding chemical reaction equation is as follows:

[0019] MgCl2·(6H2O)+3MgO+5H2O==2Mg2(OH)3Cl·4H2O(1)

[0020] MgCl2·(6H2O)+5MgO+7H2O==2Mg3(OH)5Cl·4H2O(2)

[0021] Among them, the product obtained by the reaction according to formula 1 is Mg2(OH)3Cl·4H2O. The product obtained by the reaction according to formula 2 is Mg3(OH)5Cl·4H2O. Which configuration is generated depends mainly on the feed ratio. Magnesium oxide is an alkaline oxide, so only a small amount of alkaline pH regulator needs to be added to promote the above synthesis reaction, which is very important for the recycling of mother liquor.

[0022] A method for preparing basic magnesium chloride comprises the following steps: firstly dissolving magnesium chloride in water, heating to 50-95 DEG C, stirring for 1-2 hours, and obtaining a colorless and transparent first solution; slowly adding magnesium oxide into the first solution, adding alkali to adjust the pH value to 8-10, and keeping the temperature and stirring for 1-4 hours to obtain a second solution; slurrying the second solution into a crystallization kettle, crystallizing, centrifuging, and washing with water, and drying the filter cake at 80-105 DEG C to obtain a white product basic magnesium chloride, and the mother liquor water is circulated for the above-mentioned synthesis reaction.

[0023] The magnesium chloride is at least one of anhydrous magnesium chloride and magnesium chloride hexahydrate with a purity of more than 90%.

[0024] The mass concentration of the first solution is 10-60%.

[0025] The magnesium oxide has a purity of more than 90% and a density of 2.8-3.6 g / cm 3 .

[0026] The alkali is at least one of sodium bicarbonate, sodium carbonate, sodium hydroxide and calcium hydroxide.

[0027] The molar ratio of the magnesium chloride to the magnesium oxide is 1:(2-6).

[0028] Example 1

[0029] First, 107g of magnesium chloride hexahydrate with a purity of 95% was dissolved in 300g of water, heated to 90°C, and stirred for 1h to obtain a colorless and transparent first solution; 84.84g of magnesium chloride with a purity of 95% and a density of 3.6g / cm2 was slowly added to the first solution. 35 g of magnesium oxide was added, 5 g of sodium hydroxide was added to adjust the pH to 8.5, and the mixture was kept warm and stirred for 3 h to obtain a second solution; the second solution was slurried into a crystallization kettle, crystallized, centrifuged, and washed with water, and the filter cake was dried at 80 ° C for 4 h to obtain 215.73 g of a white product.

[0030] Example 2

[0031] First, 50.11 g of anhydrous magnesium chloride with a purity of 95% was dissolved in 300 g of the above synthetic mother solution (if insufficient, water was added), heated to 50°C, and stirred for 1 hour to obtain a colorless and transparent first solution; 74.24 g of anhydrous magnesium chloride with a purity of 95% and a density of 3.6 g / cm was slowly added to the first solution. 3 5 g of magnesium oxide was added, and 5 g of sodium carbonate was added to adjust the pH to 8.2. The mixture was kept warm and stirred for 4 h to obtain a second solution. The second solution was slurried into a crystallization kettle, crystallized, centrifuged, and washed with water. The filter cake was dried at 80 ° C for 4 h to obtain 210.55 g of a white product.

[0032] Example 3

[0033] First, 50.11 g of anhydrous magnesium chloride with a purity of 95% was dissolved in 350 g of the above synthetic mother solution (the insufficient amount was supplemented with water), heated to 95°C, and stirred for 2 hours to obtain a colorless and transparent first solution; 127.26 g of 95% pure magnesium chloride with a density of 2.8 g / cm2 was slowly added to the first solution. 3 8 g of magnesium oxide was added, and the pH value was adjusted to 9.1 by adding 8 g of sodium hydroxide. The mixture was kept warm and stirred for 4 h to obtain a second solution. The second solution was slurried into a crystallization kettle, crystallized, centrifuged, and washed with water. The filter cake was dried at 100 ° C for 4 h to obtain 263.48 g of a white product.

[0034] Example 4

[0035] First, 107g of magnesium chloride hexahydrate with a purity of 95% was dissolved in 300g of the above synthetic mother solution (the insufficient amount was supplemented with water), heated to 85°C, and stirred for 2h to obtain a colorless and transparent first solution; 100g of magnesium chloride with a purity of 95% and a density of 2.8g / cm2 was slowly added to the first solution. 3 10 g of sodium hydroxide was added to adjust the pH to 9.5, and the mixture was kept warm and stirred for 4 h to obtain a second solution. The second solution was slurried into a crystallization kettle, crystallized, centrifuged, and washed with water. The filter cake was dried at 80 ° C for 4 h to obtain 235.33 g of a white product.

[0036] Example 5

[0037] First, 107g of magnesium chloride hexahydrate with a purity of 95% was dissolved in 300g of the above synthetic mother solution (the insufficient amount was supplemented with water), heated to 90°C, and stirred for 1h to obtain a colorless and transparent first solution; 80g of magnesium chloride with a purity of 95% and a density of 3.2g / cm2 was slowly added to the first solution. 310 g of magnesium oxide was added, and 10 g of sodium carbonate was added to adjust the pH to 8.8, and the mixture was kept warm and stirred for 3 h to obtain a second solution; the second solution was slurried into a crystallization kettle, crystallized, centrifuged, and washed with water, and the filter cake was dried at 80 ° C for 4 h to obtain 216.26 g of a white product.

[0038] In order to further illustrate the advantages of the method for preparing basic magnesium chloride provided by the present invention, especially the advantages of mother liquor circulation, a comparative experiment is now conducted in combination with existing technologies.

[0039] Comparative Example 1

[0040] First, 107g of magnesium chloride hexahydrate with a purity of 95% was dissolved in 350g of water, heated to 90°C, and stirred for 2h to obtain a colorless and transparent first solution; 127.26g of magnesium chloride with a purity of 95% and a density of 2.8g / cm2 was slowly added to the first solution. 3 The mixture was stirred for 24 hours while maintaining the temperature to obtain a second solution. The second solution was vacuum filtered, and the filter cake was washed with water 5 times and then with isopropanol 5 times. The filter cake was dried at 100°C for 4 hours to obtain 231.35 g of a white product.

[0041] Comparative Example 2

[0042] First, 107g of magnesium chloride hexahydrate with a purity of 95% was dissolved in 350g of the above mother liquor (the insufficient amount was supplemented with water), heated to 90°C, and stirred for 2h to obtain a colorless and transparent first solution; 127.26g of magnesium chloride with a purity of 95% and a density of 2.8g / cm2 was slowly added to the first solution; 3 The mixture was stirred for 24 hours while maintaining the temperature to obtain a second solution. The second solution was vacuum filtered, and the filter cake was washed with water 5 times and then with isopropanol 5 times. The filter cake was dried at 100°C for 4 hours to obtain 227.63 g of a white product.

[0043] Comparative Example 3

[0044] First, 107g of magnesium chloride hexahydrate with a purity of 95% was dissolved in 350g of the above mother solution (the insufficient amount was supplemented with water), heated to 90°C, and stirred for 2h to obtain a colorless and transparent first solution; 127.26g of magnesium chloride with a purity of 95% and a density of 2.8g / cm2 was slowly added to the first solution. 3 The mixture was stirred for 4 h while maintaining the temperature to obtain a second solution. The second solution was vacuum filtered, and the filter cake was washed with water 5 times and then with isopropanol 5 times. The filter cake was dried at 100 °C for 4 h to obtain 237.18 g of a white product.

[0045] The test data of Examples 1-5 and Comparative Examples 1-3 are shown in Table 1 below.

[0046] Table 1 Example test data

[0047] serial number Magnesium content (theoretical) / % Chlorine content (theoretical) / % Magnesium content / % Chlorine content / % <![CDATA[Mg2(OH)3Cl·4H2O]]> 23.47 17.11 -- -- <![CDATA[Mg3(OH)5Cl·4H2O]]> 27.47 13.35 -- -- Example 1 -- -- 26.35 16.22 Example 2 -- -- 24.58 16.87 Example 3 -- -- 28.64 12.43 Example 4 -- -- 25.52 15.79 Example 5 -- -- 27.05 16.38 Comparative Example 1 -- -- 27.67 11.95 Comparative Example 2 -- -- 30.42 9.86 Comparative Example 3 -- -- 32.05 8.51

[0048] By analyzing Examples 1-5 in Table 1, it can be found that except for Example 3, the magnesium and chlorine contents of the remaining Examples are between the theoretical contents of the two configurations of Mg2(OH)3Cl·4H2O and Mg3(OH)5Cl·4H2O, indicating that the product is a mixture of the two configurations. The magnesium oxide feed ratio of Example 3 exceeds the ratio of Reaction Formula 1 and Reaction Formula 2. It is speculated that magnesium oxide or magnesium hydroxide remains in the product, resulting in a high magnesium content. Therefore, to obtain a product of a preferred configuration, it can be achieved by adjusting the amount of magnesium oxide added.

[0049] From the product yields of Examples 1-5, all yield values ​​are higher than the actual feed amount, because the solvent water, as one of the reactants, participates in the reaction and becomes a part of the product, resulting in a yield much higher than the feed amount. At the same time, it is also proved that the preparation method of basic magnesium chloride provided by the present invention has the characteristics of high yield and high efficiency.

[0050] Analysis of the test results of Examples 2-5 shows that the mother solution can be used in a good manner.

[0051] Further, the product of Example 2 was subjected to XRD diffraction analysis, and it was found that the XRD diffraction pattern of Example 2 was basically consistent with the standard pattern of Mg2(OH)3Cl·4H2O, indicating that the main configuration of Example 2 was Mg2(OH)3Cl·4H2O. Figure 1 .

[0052] By analyzing Comparative Examples 1-3 again, it can be found that the chlorine content of the comparative examples is all low, and the reaction time of Comparative Examples 1 and 2 is too long, which seriously affects the efficiency. Comparative Examples 2 and 3 are mother liquor recycling experiments, and the conditions of Comparative Example 2 are not changed, and the reaction time of Comparative Example 3 is shortened to 4h. The results show that the magnesium content is high and the chlorine content is very low, indicating that the synthesis reaction is incomplete and the mother liquor recycling effect is not good.

[0053] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0054] The above embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present invention. It should be pointed out that, for those of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention.

Claims

1. A method for preparing basic magnesium chloride, characterized in that: First, dissolve magnesium chloride in water, heat to 50-95°C, and stir for 1-2 hours to obtain a colorless and transparent first solution; add magnesium oxide to the first solution, add alkali to adjust the pH to 8-10, keep warm and continue stirring for 1-4 hours to obtain a second solution; The second solution is slurried into a crystallization kettle, crystallized, centrifuged, and washed with water. The filter cake is dried at 80-105° C. to obtain a white product, basic magnesium chloride. The mother liquor water is recycled for the above-mentioned synthesis reaction.

2. A method for preparing basic magnesium chloride according to claim 1, characterized in that: The magnesium chloride is at least one of anhydrous magnesium chloride and magnesium chloride hexahydrate with a purity of more than 90%.

3. A method for preparing basic magnesium chloride according to claim 1, characterized in that: The mass concentration of the first solution is 10-60%.

4. A method for preparing basic magnesium chloride according to claim 1, characterized in that: The magnesium oxide has a purity of more than 90%, including light and heavy magnesium oxide, and a density of 2.8-3.6 g / cm 3 .

5. A method for preparing basic magnesium chloride according to claim 1, characterized in that: The alkali is at least one of sodium bicarbonate, sodium carbonate, sodium hydroxide and calcium hydroxide.

6. The method for preparing basic magnesium chloride according to claim 1, wherein: The molar ratio of the magnesium chloride to the magnesium oxide is 1:(2-6).

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