Preparation method of high-quality magnesium oxide

Abstract

The application provides a preparation method of high-quality magnesium oxide and belongs to the technical field of magnesium metal oxide synthesis. The application uses magnesium hydroxide waste produced in an ethyl maltol process as raw material, and obtains magnesium oxide through sodium hypochlorite oxidation, twice water washing and calcination. The obtained magnesium oxide has high purity and high activity. The process flow of the application is short, the calcination temperature is low, the side reaction is less, the subsequent equipment investment is less, the price of sodium hypochlorite is relatively low, the cost is saved, new impurities are not introduced, and the application has good industrial application value.

Description

Technical Field

[0001] This invention belongs to the field of magnesium metal oxide synthesis technology, specifically relating to a method for preparing high-quality magnesium oxide. Background Technology

[0002] Magnesium oxide, also known as magnesia or magnesium oxide, exists in nature in a free state in periclase ore. Magnesium oxide is the core of magnesium compounds and a raw material for other high-purity magnesium compounds. In recent years, the applications of magnesium oxide have been continuously developed, with increasing demand for its use as a heat-resistant material, high-temperature insulation material, lighting material, cosmetics, paint, catalyst, etc. Therefore, there is an urgent need to develop and research high-quality magnesium oxide.

[0003] Currently, the main methods for producing magnesium oxide are calcining magnesium hydroxide or magnesite. Common methods for producing magnesium oxide from magnesite include the carbonation method, acid hydrolysis method, and soda ash method. The carbonation method involves calcining solid magnesite or other minerals into powder, nitrifying it, then carbonizing it again, heating and hydrolyzing it to produce basic magnesium carbonate, which is then dried and calcined to obtain light magnesium oxide. However, this method results in low product purity, a long process flow, and high equipment investment. The acid hydrolysis method includes acid hydrolysis, calcination, calcium separation, acid dissolution, magnesium precipitation, and calcination steps. This method produces many impurity ions, consumes a large amount of acid, and is costly. The soda ash method involves reacting brine with soda ash to produce basic magnesium carbonate precipitate, which is then washed, dehydrated, and calcined to obtain magnesium oxide. This method is costly, energy-intensive, and has a complex production process. Currently, there is considerable research on the production of magnesium oxide from magnesite. For example, patent CN106745103A discloses a method for preparing magnesium oxide from magnesite, which includes calcining the magnesite, then leaching it in an ammonium salt solution, filtering to obtain a magnesium salt leachate, reacting it with ammonia water to obtain magnesium hydroxide precipitate, and then calcining it to obtain magnesium oxide. Another example is patent CN113772970A, which discloses a method for preparing magnesium oxide from magnesite, which includes screening the magnesite flotation concentrate into at least two particle sizes and subjecting each to fluidized bed calcination to obtain magnesium oxide. However, research on the production of magnesium oxide from strong magnesia is relatively limited.

[0004] Currently, the main industrial process for preparing magnesium oxide involves: first, crushing the magnesium hydroxide filter cake; then, incinerating the organic matter in a rotary kiln at 1100℃; and finally, calcining it twice at 800℃ to obtain magnesium oxide. This method easily carbonizes the organic matter, causing pore blockage. Moreover, the prepared magnesium oxide contains a large amount of organic matter, resulting in poor quality, low activity, and high energy consumption and cost. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a method for preparing high-quality magnesium oxide. This invention uses magnesium hydroxide waste, a byproduct of the ethyl maltol process, as raw material, and utilizes sodium hypochlorite as an oxidant to oxidize the magnesium hydroxide to obtain magnesium oxide. The resulting magnesium oxide has high purity and high activity. Furthermore, this invention features a simple process flow, few side reactions, minimal investment in subsequent equipment, and uses relatively inexpensive sodium hypochlorite, thus saving costs. It also does not introduce new impurities and possesses significant industrial application value.

[0006] To achieve the above objectives, this application adopts the following technical solution:

[0007] A method for preparing high-quality magnesium oxide includes the following steps:

[0008] Step 1: Grind the magnesium hydroxide waste, add pure water to make a slurry, add sodium hypochlorite for oxidation, filter, and obtain crude magnesium hydroxide I;

[0009] Step 2: Wash crude magnesium hydroxide I with water and filter to obtain crude magnesium hydroxide II;

[0010] Step 3: Dry the crude magnesium hydroxide II, grind and sieve it, and calcine it to obtain the magnesium oxide.

[0011] Optionally, in step one, the magnesium hydroxide waste is a byproduct generated in the process of producing ethyl maltol from furfural; the magnesium hydroxide waste contains: 69.85-89.98% magnesium hydroxide, 10-30% water, 0.01-0.1% 5-ethyl-2(5H)-furanone and 0.01-0.05% furfural.

[0012] Optionally, in step one, the mass ratio of the magnesium hydroxide waste to water is 1:1-3; preferably, the mass ratio of the magnesium hydroxide waste to water is 1:3.

[0013] Optionally, in step one, the pulping conditions are: time 5-10 min, temperature 50-70℃; preferably, the pulping conditions are: time 10 min, temperature 60℃.

[0014] Optionally, in step one, the amount of sodium hypochlorite added is 5-25% of the mass of the magnesium hydroxide waste; preferably, the amount of sodium hypochlorite added is 10% of the mass of the magnesium hydroxide waste.

[0015] Optionally, in step two, the water washing is performed 2-3 times.

[0016] Optionally, in step two, during the water washing process, the mass ratio of crude magnesium hydroxide I to water is 1:1-3, the water washing time is 5-30 min, and the temperature is 50-70℃.

[0017] Optionally, in step three, the drying temperature is 80-110℃, and the crude magnesium hydroxide is dried until the water content is 0.01-0.1%.

[0018] Optionally, in step three, the mesh size of the sieve used for sieving is 40-80 mesh.

[0019] Optionally, in step three, the calcination temperature is 800-1000℃ and the time is 0.5-3h.

[0020] The beneficial effects of this invention are:

[0021] (1) This invention uses magnesium hydroxide, a waste product generated in the ethyl maltol process, as a raw material to prepare magnesium oxide. This not only treats the by-product waste and avoids environmental pollution, but also allows the waste to be recycled and reused, effectively realizing the comprehensive utilization of resources and greatly saving raw material costs.

[0022] (2) The process flow of the present invention is short, which helps to reduce the occurrence of side reactions, has low cost, requires less investment in subsequent equipment, and has good industrial application value.

[0023] (3) This invention requires only one firing, which significantly reduces energy consumption and saves costs.

[0024] (4) Compared with hydrogen peroxide, ozone and potassium permanganate, the present invention uses sodium hypochlorite as an oxidant, which will not introduce new impurities, improve product purity, enhance activity, and reduce costs.

[0025] (5) The magnesium oxide product obtained by this invention has high purity and high activity. Detailed Implementation

[0026] The following non-limiting embodiments are intended to enable those skilled in the art to gain a more comprehensive understanding of the present invention, but do not limit the invention in any way. The following description is merely an exemplary illustration of the scope of protection of the present invention, and those skilled in the art can make various changes and modifications to the invention based on the disclosed content, which should also fall within the scope of protection of the present invention.

[0027] The present invention will be further described below by way of specific embodiments. Unless otherwise specified, all chemical reagents used in the embodiments of the present invention are obtained through conventional commercial means.

[0028] Example 1

[0029] Raw material: Components of magnesium hydroxide waste

[0030] Table 1

[0031] Components content(%) <![CDATA[Mg(OH)2]]> 89.96 5-Ethyl-2(5H)-furanone 0.02 furfural 0.01 water 10.01

[0032] The preparation of high-quality magnesium oxide from the aforementioned magnesium hydroxide waste includes the following steps:

[0033] Step 1: Take 1000g of magnesium hydroxide waste and grind it. Add 3000mL of water and slurry it at 60℃ for 10min. Add 100g of sodium hypochlorite and oxidize it at 70℃ for 3h. Filter to obtain 763g of crude magnesium hydroxide I.

[0034] Step 2: Add 2300mL of water to crude magnesium hydroxide I, wash with water at 70℃ for 0.5h, filter, then add 2300mL of water, wash with water at 70℃ for 0.5h, to obtain crude magnesium hydroxide II 702g;

[0035] Step 3: Dry the crude magnesium hydroxide II at 110°C until the moisture content is 0.02%, grind it through an 80-mesh sieve, and then calcine it at 1000°C for 3.0 hours in a rotary tube furnace to obtain the magnesium oxide.

[0036] Example 2

[0037] Raw material: Components of magnesium hydroxide waste

[0038] Table 2

[0039]

[0040]

[0041] The preparation of high-quality magnesium oxide from the aforementioned magnesium hydroxide waste includes the following steps:

[0042] Step 1: Take 1000g of magnesium hydroxide waste and grind it. Add 2000mL of pure water and slurry it at 50℃ for 10min. Add 100g of sodium hypochlorite and oxidize it at 60℃ for 2h. Filter to obtain 701g of crude magnesium hydroxide I.

[0043] Step 2: Add 1500mL of water to crude magnesium hydroxide I, wash with water at 60℃ for 20min, filter, then add 1500mL of water, wash with water at 60℃ for 20min to obtain crude magnesium hydroxide II 649g;

[0044] Step 3: Dry the crude magnesium hydroxide II at 90°C until the moisture content is 0.02%, grind it through a 60-mesh sieve, and then calcine it at 900°C for 2.0 hours in a rotary tube furnace to obtain the magnesium oxide.

[0045] Example 3

[0046] Raw material: Components of magnesium hydroxide waste

[0047] Table 3

[0048] Components content(%) <![CDATA[Mg(OH)2]]> 70.16 5-Ethyl-2(5H)-furanone 0.06 furfural 0.04 water 29.74

[0049] The preparation of high-quality magnesium oxide from the aforementioned magnesium hydroxide waste includes the following steps:

[0050] Step 1: Take 1000g of magnesium hydroxide waste and grind it. Add 1000mL of pure water and slurry it at 70℃ for 5min. Add 100g of sodium hypochlorite and oxidize it at 50℃ for 1h. Filter to obtain 667g of crude magnesium hydroxide I.

[0051] Step 2: Add 1000mL of water to crude magnesium hydroxide I, wash with water at 50℃ for 10min, filter, then add 1000mL of water, wash with water at 50℃ for 10min to obtain crude magnesium hydroxide II 618g;

[0052] Step 3: Dry the crude magnesium hydroxide II at 80°C until the moisture content is 0.02%, grind it through a 40-mesh sieve, and then calcine it at 800°C for 1.0 h in a rotary tube furnace to obtain the magnesium oxide.

[0053] Comparative Example 1

[0054] Raw material: Components of magnesium hydroxide waste

[0055] Table 4

[0056] Components content(%) <![CDATA[Mg(OH)2]]> 75.91 5-Ethyl-2(5H)-furanone 0.05 furfural 0.02 water 24.02

[0057] The preparation of high-quality magnesium oxide from the aforementioned magnesium hydroxide waste includes the following steps:

[0058] 1000g of magnesium hydroxide waste was dried at 110℃ to a moisture content of 0.02%, ground, and passed through an 80-mesh sieve. Then, in a rotary tube furnace, it was first calcined at 1100℃ for 1 hour, and then calcined twice at 800℃ for 1 hour each time. After calcination, high-quality magnesium oxide was obtained.

[0059] Comparative Example 2

[0060] Raw material: Components of magnesium hydroxide waste

[0061] Table 5

[0062] Components content(%) <![CDATA[Mg(OH)2]]> 74.89 5-Ethyl-2(5H)-furanone 0.08 furfural 0.04 water 24.99

[0063] The preparation of high-quality magnesium oxide from the aforementioned magnesium hydroxide waste includes the following steps:

[0064] 1000g of magnesium hydroxide waste was ground and added to 2000mL of water. The mixture was washed at 65℃ for 30min and filtered to obtain 702.91g of crude magnesium hydroxide. Then, it was added to 1500mL of water and washed at 65℃ for 30min and filtered to obtain 688.16g of crude magnesium hydroxide. Then, it was added to 1500mL of water and washed at 65℃ for 30min and filtered to obtain 678.96g of crude magnesium hydroxide. The mixture was then dried to a moisture content of 0.02%, ground through an 80-mesh sieve, and finally calcined at 1000℃ for 3.0h to obtain the magnesium oxide.

[0065] Comparative Example 3

[0066] Raw material: Components of magnesium hydroxide waste

[0067] Table 6

[0068] Components content(%) <![CDATA[Mg(OH)2]]> 84.53 5-Ethyl-2(5H)-furanone 0.04 furfural 0.02 water 15.41

[0069] The preparation of high-quality magnesium oxide from the aforementioned magnesium hydroxide waste includes the following steps:

[0070] Step 1: Take 1000g of magnesium hydroxide waste and grind it. Add 3000mL of water and slurry it at 60℃ for 10min. Add 100g of hydrogen peroxide and oxidize it at 70℃ for 3h. Filter it to obtain 746g of crude magnesium hydroxide I.

[0071] Step 2: Add 2300mL of water to crude magnesium hydroxide I, wash with water at 70℃ for 0.5h, filter, then add 2300mL of water, wash with water at 70℃ for 0.5h, to obtain 691g of crude magnesium hydroxide II;

[0072] Step 3: Dry the crude magnesium hydroxide II to a moisture content of 0.02%, grind it through an 80-mesh sieve, and then calcine it at 1000℃ for 3.0h in a rotary tube furnace to obtain the magnesium oxide.

[0073] Comparative Example 4

[0074] Raw material: Components of magnesium hydroxide waste

[0075] Table 7

[0076] Components content(%) <![CDATA[Mg(OH)2]]> 79.89 5-Ethyl-2(5H)-furanone 0.06 furfural 0.02 water 20.03

[0077] The preparation of high-quality magnesium oxide from the aforementioned magnesium hydroxide waste includes the following steps:

[0078] Step 1: Take 1000g of magnesium hydroxide waste and grind it. Add 3000mL of water and slurry it at 60℃ for 10min. Add 100g of ozone and oxidize it at 70℃ for 3h. Filter it to obtain 712g of crude magnesium hydroxide I.

[0079] Step 2: Add 2300mL of water to crude magnesium hydroxide I, wash with water at 70℃ for 0.5h, filter, then add 2300mL of water, wash with water at 70℃ for 0.5h to obtain crude magnesium hydroxide II 651g;

[0080] Step 3: Dry the crude magnesium hydroxide II to a moisture content of 0.02%, grind it through an 80-mesh sieve, and then calcine it at 1000℃ for 3.0h in a rotary tube furnace to obtain the magnesium oxide.

[0081] Comparative Example 5

[0082] Raw material: Components of magnesium hydroxide waste

[0083] Table 8

[0084] Components content(%) <![CDATA[Mg(OH)2]]> 85.47 5-Ethyl-2(5H)-furanone 0.05 furfural 0.03 water 14.45

[0085] The preparation of high-quality magnesium oxide from the aforementioned magnesium hydroxide waste includes the following steps:

[0086] Step 1: Take 1000g of magnesium hydroxide waste and grind it. Add 3000mL of water and slurry it at 60℃ for 10min. Add 100g of potassium permanganate and oxidize it at 70℃ for 3h. Filter to obtain 755g of crude magnesium hydroxide I.

[0087] Step 2: Add 2300mL of water to crude magnesium hydroxide I, wash with water at 70℃ for 0.5h, filter, then add 2300mL of water, wash with water at 70℃ for 0.5h to obtain 601g of crude magnesium hydroxide II;

[0088] Step 3: Dry the crude magnesium hydroxide II to a moisture content of 0.02%, grind it through an 80-mesh sieve, and then calcine it at 1000℃ for 3.0h in a rotary tube furnace to obtain the magnesium oxide.

[0089] Test case

[0090] The composition and activity of magnesium oxide prepared in Examples 1-3 and Comparative Examples 1-5 were detected by the following methods:

[0091] Detection of magnesium oxide content: The determination shall be carried out in accordance with HG / T 2573-2006.

[0092] Determination of citric acid value: Measure 100 mL of 0.1 M citric acid solution and turn on the sonicator. Weigh 2.030 g ± 0.001 g of magnesium oxide product and quickly pour it into the above citric acid solution. Start timing with a stopwatch while rapidly stirring the solution with a glass rod. The endpoint is when the solution just turns red. Record the number of seconds, which is the citric acid value of the sample.

[0093] Iodine uptake value determination: The determination shall be carried out in accordance with HG / T 3928-2012.

[0094] Moisture content detection: Weigh 10g of sample, accurate to 0.0001g, and place it in a weighing bottle that has been kept constant at 130℃. Dry it in an electric oven at 130℃ until constant weight, and calculate the moisture content using the mass change before and after drying.

[0095] Chloride ion content detection: Dissolve 0.2g of magnesium oxide in sulfuric acid and dilute to 100mL, record as solution A, and proceed according to V. 溶液A :V 硝酸钾 After mixing at a 1:1 ratio, chloride ion concentration is measured, and calculations are performed based on the displayed values.

[0096] The test results are shown in Table 9 below.

[0097] Table 9

[0098]

[0099] As shown in the table, the magnesium oxide product obtained by this invention has a purity of up to 99.53%, low citric acid value, and high iodine uptake value, indicating high purity and high activity. The magnesium oxide products obtained in Comparative Examples 1-5 have lower purity and activity than those in the examples, demonstrating that the type of oxidant and the oxidation and washing treatments have a significant impact on the purity and activity of the magnesium oxide product.

[0100] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A method for preparing high-quality magnesium oxide, characterized in that, Includes the following steps: Step 1: Grind the magnesium hydroxide waste, add pure water to make a slurry, add sodium hypochlorite for oxidation, filter, and obtain crude magnesium hydroxide product I; the amount of sodium hypochlorite added is 5-25% of the mass of the magnesium hydroxide waste. Step 2: Wash crude magnesium hydroxide I with water and filter to obtain crude magnesium hydroxide II; the number of water washings is 2-3 times; during the water washing process, the mass ratio of crude magnesium hydroxide I to water is 1:1-3, the water washing time is 5-30 min, and the temperature is 50-70℃. Step 3: Dry the crude magnesium hydroxide II, grind and sieve it, and calcine it to obtain the magnesium oxide.

2. The preparation method according to claim 1, characterized in that, The magnesium hydroxide waste is a byproduct of the production of ethyl maltol from furfural; the magnesium hydroxide waste contains: 69.85-89.98 w / w of magnesium hydroxide, 10-30 w / w of water, 0.01-0.1 w / w of 5-ethyl-2(5H)-furanone, and 0.01-0.05 w / w of furfural.

3. The preparation method according to claim 1, characterized in that, In step one, the mass ratio of the magnesium hydroxide waste to water is 1:1-3.

4. The preparation method according to claim 1, characterized in that, In step one, the pulping conditions are: time 5-10 min, temperature 50-70℃.

5. The preparation method according to claim 1, characterized in that, In step one, the amount of sodium hypochlorite added is 10% of the mass of the magnesium hydroxide waste.

6. The preparation method according to claim 1, characterized in that, In step three, the drying temperature is 80-110℃, and the crude magnesium hydroxide is dried until the water content is 0.01-0.1%.

7. The preparation method according to claim 1, characterized in that, In step three, the sieve mesh size is 40-80 mesh.

8. The preparation method according to claim 1, characterized in that, In step three, the calcination temperature is 800-1000℃ and the time is 0.5-3h.

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