Method for preparing light magnesium oxide from ethyl maltol waste residues

Abstract

The invention discloses a method for preparing light magnesium oxide from ethyl maltol waste residues, and belongs to the technical field of industrial waste residue resource utilization, basic magnesium chloride waste residues generated in the Grignard section of ethyl maltol are used as raw materials, and high-quality light magnesium oxide is generated after hydrolysis, carbon dioxide carbonization and calcination. The method effectively solves the problem of treatment of the ethyl maltol production waste residues, and meanwhile magnesium oxide prepared by a carbonization method is small in stacking density and low in chloride ion content and has great advantages compared with methods such as direct calcination. In addition, by adjusting the equivalent weight of carbon dioxide and controlling the carbonization temperature, the calcination time and temperature and the like, all indexes reach the standard of light magnesium oxide superior products, and the method is a technical invention which is simple, efficient, low in cost, environmentally friendly and capable of being circularly developed.

Description

Technical Field

[0001] The invention belongs to the technical field of resource utilization of industrial waste residues, and specifically relates to a method for preparing light magnesium oxide by utilizing ethyl maltol waste residues. Background Art

[0002] A large amount of basic magnesium chloride waste slag will be produced in the Grignard reaction section of the ethyl maltol production line. The treatment of this solid waste will not only increase economic expenditure, but also cause waste of resources. At present, some factories simply hydrolyze the basic magnesium chloride waste slag and directly calcine it to obtain magnesium oxide for sale to increase its added value and reduce costs and increase efficiency as much as possible. However, due to the limitations of bulk density, chloride ion content and whiteness, this type of magnesium oxide cannot enter the high-end market and cannot maximize the benefits of the product. This is also a great loss for the company. Therefore, it is particularly critical to optimize and improve the existing magnesium oxide process route to prepare high-quality lightweight magnesium oxide.

[0003] Literature (He Zhaoping, Preparation of Magnesium Oxide from Ethyl Maltol Waste Residue [D]. Xiangtan University, 2007) reports the use of filtrate after hydrolysis of basic magnesium chloride waste residue to generate basic magnesium carbonate through carbon ammonium process, and then further calcination to obtain magnesium oxide. Although this method can obtain lightweight magnesium oxide, the ratio of ammonium bicarbonate and ammonia water must also be strictly controlled, otherwise some magnesium hydroxide will be additionally generated. At the same time, in order to obtain magnesium oxide with low chlorine content, a large amount of water washing is required, which is not only a waste of water resources, but also produces a large amount of wastewater rich in ammonia nitrogen, which is more troublesome to handle.

[0004] The patent with publication number CN113213511 A discloses a method for recovering high-purity magnesium oxide from ethyl maltol waste residue as raw material. The method is to recover and prepare high-purity magnesium oxide from ethyl maltol waste residue as raw material. First, the ethyl maltol waste residue is first crushed into blocks and dried to remove most of free water and volatile organic matter. Then, it is crushed in a pulverizer, and carbon powder is added during the crushing process. The material is placed in a rotary tube furnace for calcination. The calcined material is taken out and placed in a liquid. A stirring method is used to promote the reaction to obtain a precipitate. The precipitate is filtered to obtain a precipitate, and the precipitate is dried and crushed to obtain a powdered hydrate. Finally, the hydrate is placed in a rotary tube furnace for calcination to obtain magnesium oxide. Although the magnesium oxide obtained by this method has high purity, it is not possible to remove chloride ions and reduce bulk density.

[0005] Based on this, we proposed a new method for preparing lightweight magnesium oxide using ethyl maltol waste residue, which can solve the problems of the existing technology, such as complicated process, high cost, and inability to effectively reduce the bulk density and chloride ion content. Summary of the invention

[0006] The purpose of the present invention is to provide a method for preparing light magnesium oxide by utilizing ethyl maltol waste residue in view of the existing problems.

[0007] The present invention is achieved through the following technical solutions:

[0008] A method for preparing light magnesium oxide using ethyl maltol waste residue comprises the following steps:

[0009] S1, adding the basic magnesium chloride waste residue produced in the ethyl maltol Grignard process and 2 to 4 times the mass of water into a reactor, stirring at T0°C and filtering to obtain a magnesium hydroxide filter cake;

[0010] S2, take n×mg magnesium hydroxide filter cake and add it into a four-necked flask, then add water into the flask, stir to make it evenly dispersed, and then introduce CO2 gas into the system at a temperature of T1°C for carbonization treatment;

[0011] S3. After the carbonization is completed, the temperature of the system is raised to T2°C and then kept warm. The turbid liquid in the flask is then filtered and dried.

[0012] S4. Finally, calcination is performed at T3°C to obtain light magnesium oxide.

[0013] Preferably, the T0 in step S1 is controlled at 75-95° C., and the stirring time is controlled at 1-3 h.

[0014] Preferably, n described in step S2 is the mass of the magnesium hydroxide filter cake, n is controlled to be 20 to 50, and m is a multiple.

[0015] Preferably, the liquid-to-solid ratio of water to magnesium hydroxide filter cake in step S2 is 1:5-20.

[0016] Preferably, T1 in step S2 is controlled at 25-55°C.

[0017] Preferably, the flow rate of CO2 in step S2 is controlled at m×(80-160) mL / min.

[0018] Preferably, the carbonization time of CO2 gas in step S2 is controlled within 0.5 to 3 hours.

[0019] Preferably, T2 in step S3 is controlled at 65-95° C., and the insulation time is controlled at 0.5-2 h.

[0020] Preferably, the calcination temperature T3 in step S4 is controlled at 600-900° C., and the calcination time is controlled at 0.5-2 h.

[0021] Compared with the prior art, the present invention has the following advantages:

[0022] The present invention provides a method for preparing light magnesium oxide by using ethyl maltol waste residue. The present invention effectively solves the problem of treating ethyl maltol production waste residue. At the same time, the magnesium oxide prepared by the carbonization method has a small bulk density and a low chloride ion content, which is very advantageous compared with direct calcination and other methods. In addition, the present invention adjusts the carbon dioxide equivalent, controls the carbonization temperature, and the calcination time and temperature, so that various indicators reach the standard of light magnesium oxide superior products, and has the characteristics of being simple, efficient, low-cost, and in line with green and recyclable development. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a process flow chart of the present invention;

[0024] Figure 2 It is the XRD pattern of the product of each stage of the present invention. DETAILED DESCRIPTION

[0025] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. 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.

[0026] Example 1

[0027] A method for preparing light magnesium oxide using ethyl maltol waste residue comprises the following steps:

[0028] S1. Add 1 kg of basic magnesium chloride waste residue produced in the ethyl maltol Grignard process and 2 kg of water into a reactor, stir at 80° C. for 1 hour, and then filter to obtain a magnesium hydroxide filter cake;

[0029] S2, take 30g of magnesium hydroxide filter cake and add it to a four-necked flask, then add 15 times of water to the flask, stir to make it evenly dispersed, then at a temperature of 50°C, introduce CO2 gas into the system at a flow rate of 80mL / min for carbonization for 3h;

[0030] S3. After the carbonization is completed, the temperature of the system is raised to 70°C and kept warm for 0.5h, and then the turbid liquid in the flask is filtered and dried;

[0031] S4. Finally, calcination is carried out at 700°C for 0.5h to obtain light magnesium oxide.

[0032] Example 2

[0033] A method for preparing light magnesium oxide using ethyl maltol waste residue comprises the following steps:

[0034] S1. Add 1 kg of basic magnesium chloride waste residue produced in the ethyl maltol Grignard process and 2 kg of water into a reactor, stir at 80° C. for 2 h, and then filter to obtain a magnesium hydroxide filter cake;

[0035] S2, take 30g of magnesium hydroxide filter cake and add it to a four-necked flask, then add 25 times of water to the flask, stir to make it evenly dispersed, then at a temperature of 50°C, introduce CO2 gas into the system at a flow rate of 120mL / min for carbonization for 2h;

[0036] S3. After the carbonization is completed, the temperature of the system is raised to 70°C and kept warm for 2 hours, and then the turbid liquid in the flask is filtered and dried;

[0037] S4. Finally, calcination is carried out at 700°C for 0.5h to obtain light magnesium oxide.

[0038] Example 3

[0039] A method for preparing light magnesium oxide using ethyl maltol waste residue comprises the following steps:

[0040] S1. Add 1 kg of basic magnesium chloride waste residue produced in the ethyl maltol Grignard process and 2 kg of water into a reactor, stir at 80° C. for 1 hour, and then filter to obtain a magnesium hydroxide filter cake;

[0041] S2, take 60g of magnesium hydroxide filter cake and add it to a 2L four-necked flask, then add 15 times of water to the flask, stir to make it evenly dispersed, then at a temperature of 50°C, introduce CO2 gas into the system at a flow rate of 160mL / min for carbonization for 3h;

[0042] S3. After the carbonization is completed, the temperature of the system is raised to 75°C and kept warm for 1 hour, and then the turbid liquid in the flask is filtered and dried;

[0043] S4. Finally, calcination is carried out at 800°C for 1 hour to obtain light magnesium oxide.

[0044] Example 4

[0045] A method for preparing light magnesium oxide using ethyl maltol waste residue comprises the following steps:

[0046] S1. Add 1 kg of basic magnesium chloride waste residue produced in the ethyl maltol Grignard process and 2 kg of water into a reactor, stir at 80° C. for 1 hour, and then filter to obtain a magnesium hydroxide filter cake;

[0047] S2, take 60g of magnesium hydroxide filter cake and add it to a 2L four-necked flask, then add 10 times the amount of water to the flask, stir to make it evenly dispersed, then at a temperature of 35°C, introduce CO2 gas into the system at a flow rate of 160mL / min for carbonization for 3h;

[0048] S3. After the carbonization is completed, the temperature of the system is raised to 75°C and kept warm for 1 hour, and then the turbid liquid in the flask is filtered and dried;

[0049] S4. Finally, calcination is carried out at 800°C for 1 hour to obtain light magnesium oxide.

[0050] Detection

[0051] Light magnesium oxide was prepared respectively by the methods of the above-mentioned Example 1, Example 2 and Example 3, and then each group of samples was tested.

[0052] The test results are shown in Table 1 below.

[0053] Table 1 Test results of three examples of samples

[0054]

[0055] From the results in Table 1 above, it can be concluded that the method for preparing light magnesium oxide using ethyl maltol waste residue provided by the present invention can not only turn waste into treasure, but also the magnesium oxide prepared has a magnesium oxide content of more than 95%, a bulk density of less than 0.20 g / mL, and a chloride ion content of less than 0.07%, which has reached the ranks of Class I superior magnesium oxide.

[0056] In order to further verify the effect of the present invention, the magnesium oxide sample prepared in the technical embodiment 4 of the present invention was subjected to full index detection, and the detection results are shown in Table 2 below.

[0057] Table 2 All index test results

[0058]

[0059] It can be concluded from the results in Table 2 above that the magnesium oxide prepared by the method of the present invention not only has the magnesium oxide content, bulk density, and chloride ion content that reach the level of Class I superior magnesium oxide, but also has significant advantages in other indicators.

[0060] The XRD spectra of the products in each stage are as follows: Figure 2 shown.

[0061] From the XRD graph (a), it can be clearly seen that each peak of the purchased magnesium hydroxide corresponds to PDF#44-1482, and there are no other impurity peaks, while the main peak of the factory filter cake corresponds to each peak of magnesium hydroxide, and other impurity peaks correspond to the peak of basic magnesium chloride (PDF#36-0388), indicating that basic magnesium chloride remains in the factory filter cake. From the XRD graph (b), it can be seen that the main peaks of the factory filter cake after carbonization and the purchased magnesium hydroxide after carbonization correspond to the main peak of 4MgCO3·Mg(OH)2·4H2O (PDF#25-0513), indicating that the main structure of the carbonization product of this method is basic magnesium carbonate tetrahydrate (4MgCO3·Mg(OH)2·4H2O). From the XRD graph (c), it can be seen that the raw materials, whether purchased magnesium hydroxide or factory filter cake, can be calcined into magnesium oxide after carbonization, and there are no other impurity peaks, and the crystal form is good. In summary, the intermediates in each stage of the pilot test are consistent with expectations, namely basic magnesium chloride → magnesium hydroxide → basic magnesium carbonate → magnesium oxide.

[0062] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for preparing light magnesium oxide using ethyl maltol waste residue, characterized in that: The steps include: S1, adding the basic magnesium chloride waste residue produced in the ethyl maltol Grignard process and 2 to 4 times the mass of water into a reactor, stirring at T0°C and filtering to obtain a magnesium hydroxide filter cake; S2, take n×mg magnesium hydroxide filter cake and add it into a four-necked flask, then add water into the flask, stir to make it evenly dispersed, and then introduce CO2 gas into the system at a temperature of T1°C for carbonization treatment; S3. After the carbonization is completed, the temperature of the system is raised to T2°C and then kept warm. The turbid liquid in the flask is then filtered and dried. S4. Finally, calcination is performed at T3°C to obtain light magnesium oxide.

2. A method for preparing light magnesium oxide using ethyl maltol waste residue according to claim 1, characterized in that: The T0 described in step S1 is controlled at 75-95° C., and the stirring time is controlled at 1-3 h.

3. A method for preparing light magnesium oxide using ethyl maltol waste residue according to claim 1, characterized in that: The n described in step S2 is the mass of the magnesium hydroxide filter cake, n is controlled to be 20 to 50, and m is a multiple.

4. The method for preparing light magnesium oxide using ethyl maltol waste residue according to claim 1, characterized in that: The liquid-to-solid ratio of water to magnesium hydroxide filter cake in step S2 is 1:5-20.

5. The method for preparing light magnesium oxide using ethyl maltol waste residue according to claim 1, characterized in that: The temperature T1 in step S2 is controlled at 25-55°C.

6. The method for preparing light magnesium oxide by utilizing ethyl maltol waste residue according to claim 1, characterized in that: The flow rate of CO2 described in step S2 is controlled at m×(80~160)mL / min.

7. The method for preparing light magnesium oxide by utilizing ethyl maltol waste residue according to claim 1, characterized in that: The carbonization time of CO2 gas in step S2 is controlled within 0.5 to 3 hours.

8. The method for preparing light magnesium oxide by utilizing ethyl maltol waste residue according to claim 1, characterized in that: The temperature T2 in step S3 is controlled at 65-95° C., and the insulation time is controlled at 0.5-2 h.

9. The method for preparing light magnesium oxide by utilizing ethyl maltol waste residue according to claim 1, characterized in that: The calcination temperature T3 described in step S4 is controlled at 600-900° C., and the calcination time is controlled at 0.5-2 h.

Images