Method for recycling magnesium resource in calcium-containing magnesium slag

Abstract

The invention relates to the field of hydrometallurgy, in particular to a method for recycling magnesium resources in calcium-containing magnesium slag. The method comprises the following steps: mixing magnesium slag with water for size mixing to obtain size; the slurry reacts with P507 to be saponified, and then saponified water phase slurry and saponified organic phase are separated; and carrying out solid-liquid separation on the saponified water-phase slurry to obtain calcium sulfate. According to the process method disclosed by the invention, alkaline magnesium hydroxide in the calcium-containing magnesium slag can be effectively recycled without influencing the original organic saponification process, and the cyclic utilization of magnesium resources is realized on the basis of not changing the original process. By adopting the process method disclosed by the invention, calcium sulfate with relatively high purity can be obtained, and resource utilization of calcium sulfate is realized. According to the process method disclosed by the invention, the environmental problem caused by solid waste stockpiling is greatly solved while resources are recycled.

Description

Technical Field

[0001] The invention relates to the field of hydrometallurgy, and in particular to a method for recycling magnesium resources in calcium-magnesium-containing slag. Background Art

[0002] Magnesium hydroxide is widely used in flame retardants, sewage treatment, flue gas desulfurization and other fields due to its non-toxic, weak alkalinity, good buffering performance, no corrosion, strong chemical adsorption capacity and other characteristics. At present, the annual demand for magnesium hydroxide is greater than 500,000 tons, and the annual demand for high-purity magnesium hydroxide is about 30,000 tons. It is expected that the demand for high-purity magnesium hydroxide may exceed 100,000 tons / year in the next few years. At present, the method for producing magnesium hydroxide is mainly divided into two categories, one is the ore method, that is, magnesium hydroxide is prepared using natural magnesium ore (brucite, magnesite, etc.). The other is the chemical synthesis method, that is, magnesium hydroxide is generated by reacting brine, brine ore, etc. containing magnesium chloride with alkali in aqueous solution. The preparation of magnesium hydroxide by the ore method will cause environmental deterioration and a sharp reduction in resource reserves, and the preparation of magnesium hydroxide by the chemical synthesis method has the disadvantages of outputting by-product waste and high cost.

[0003] In the process of treating some magnesium-containing high-salt wastewater in industry, a large amount of magnesium hydroxide waste residue is often produced, resulting in a waste of magnesium resources. For example, magnesium sulfate wastewater produced in the high-temperature roasting process of mixed rare earth concentrate with concentrated sulfuric acid will produce a large amount of calcium sulfate and magnesium hydroxide mixed residue during its precipitation treatment process, which will be stored as solid waste, resulting in a waste of resources. In order to fully utilize resources, a method for recycling magnesium resources in calcium-containing magnesium slag is particularly important. Summary of the invention

[0004] The purpose of the present invention is to provide a method for recycling magnesium resources in calcium-magnesium slag. By utilizing the principle that calcium sulfate does not participate in the saponification of organic P507, magnesium hydroxide containing calcium sulfate is used as an alkaline saponifier to carry out saponification reaction with organic P507, and while recycling magnesium resources, calcium sulfate with high purity is obtained, which can be used as a raw material for building materials, and finally the resource recycling of magnesium hydroxide containing calcium sulfate is realized.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] The present invention provides a method for recycling magnesium resources in calcium-magnesium slag, comprising the following steps:

[0007] Mixing magnesium slag with water to prepare slurry to obtain slurry;

[0008] The slurry is reacted with P507 (2-ethylhexyl phosphate mono-2-ethylhexyl ester) to be saponified, and then the saponified aqueous slurry and the saponified organic phase are separated;

[0009] The saponified aqueous slurry is subjected to solid-liquid separation to obtain calcium sulfate.

[0010] The present invention discloses the following technical effects:

[0011] The process method of the invention can effectively reuse the alkaline magnesium hydroxide in the calcium-containing magnesium slag without affecting the original organic saponification process, and realize the recycling of magnesium resources without changing the original process.

[0012] The process method of the present invention can be used to obtain calcium sulfate with higher purity, thereby realizing resource utilization of calcium sulfate.

[0013] The process method of the present invention not only recycles resources, but also greatly solves the environmental problems caused by solid waste storage. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0015] Figure 1 This is a scanning electron microscope image of the calcium-magnesium slag in Example 3 of the present invention;

[0016] Figure 2 This is a scan of the energy spectrum of the calcium-magnesium slag in Example 3 of the present invention;

[0017] Figure 3 The by-product calcium sulfate (CaSO 4 ·2H 2 O) scanning electron microscope image;

[0018] Figure 4 The by-product calcium sulfate (CaSO 4 ·2H 2 O) energy spectrum scan. DETAILED DESCRIPTION

[0019] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0020] It should be understood that the terms described in the present invention are only for describing a particular embodiment and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. The intermediate value in any stated value or stated range, and each smaller range between any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0021] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0022] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to the skilled artisan. The present invention description and examples are exemplary only.

[0023] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0024] The invention relates to a method for preparing a pure CaSO4 by reacting magnesium hydroxide containing calcium sulfate with organic P507 to form saponified P507 (i.e., saponified organic phase) and saponified aqueous phase slurry, and then subjecting the saponified aqueous phase slurry to solid-liquid separation to obtain a pure CaSO4 4 ·2H 2 The present invention has a simple operation process, and utilizes the principle that calcium sulfate does not participate in the saponification of P507, and realizes the resource recycling of magnesium hydroxide slag containing calcium sulfate without affecting the use of the later saponification organic phase. The specific scheme of the present invention is as follows:

[0025] A method for recycling magnesium resources in calcium-magnesium slag comprises the following steps:

[0026] Mixing magnesium slag with water to prepare slurry to obtain slurry;

[0027] The slurry is reacted with P507 (2-ethylhexyl phosphate mono-2-ethylhexyl ester) to be saponified, and then the saponified aqueous slurry and the saponified organic phase are separated;

[0028] The saponified aqueous slurry is subjected to solid-liquid separation to obtain calcium sulfate.

[0029] In some embodiments of the present invention, the content of magnesium hydroxide in the magnesium slag is ≥20wt%.

[0030] In some embodiments of the present invention, the solid-liquid ratio of the magnesium slag to the water is 1:3-10.

[0031] In the present invention, the purpose of slurry adjustment is to fully mix. If the amount of water used is too little, the solid slurry adjustment will be insufficient. If the amount of water used is too much, the processing volume will be reduced in the same reactor, thereby lowering the processing efficiency.

[0032] In some embodiments of the present invention, the slurry is added in an amount such that the saponification degree of the P507 to be saponified is 0.5 mol / L.

[0033] In the present invention, the addition ratio of the slurry is determined according to the saponification degree of P507. The saponification degree is generally controlled at 0.5 mol / L in industry. If the saponification degree is too low, the organic material will not be fully used. If the saponification degree is too high, the system fluidity will be poor and emulsification will easily occur.

[0034] In some embodiments of the present invention, the reaction temperature is 30-60°C.

[0035] In some embodiments of the present invention, the reaction time is 0.1-2h.

[0036] In the present invention, if the reaction temperature is too low, the two-phase separation rate will be affected; if the reaction temperature is too high, there will be a chance of volatilization loss, so it needs to be controlled within a certain temperature range; if the reaction time is too long, the processing efficiency will be affected.

[0037] In some embodiments of the present invention, the step of standing is further included after the reaction is completed.

[0038] In some embodiments of the present invention, the standing time is 3-15 min.

[0039] The purpose of standing is to achieve separation of the organic phase and the aqueous phase.

[0040] The technical solutions described in the present invention, unless otherwise specified, are all conventional solutions in the art, and the reagents or raw materials used, unless otherwise specified, are purchased from commercial channels or have been disclosed.

[0041] The calculation formula of the organic loss of the reaction system in the present invention is as follows: organic loss of the reaction system = (organic volume before reaction - organic volume after reaction) * 100% / organic volume before reaction.

[0042] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0043] Example 1

[0044] First, calcium-magnesium slag containing 40% magnesium hydroxide (main component: Mg 2+ : 16.55%, SO 4 2- : 30.7%, Ca 2+ :15.49%) and tap water at a solid-liquid ratio of 1:5, and the slurry is reacted with the P507 to be saponified, and the slurry is added according to the saponification degree of P507 of 0.5mol / L, the reaction temperature is 40℃, the reaction time is 2h, and the reaction is allowed to stand for 10min. The saponified aqueous slurry is discharged from the bottom of the cone bottom reaction device to separate the saponified organic phase from the saponified aqueous slurry. The separated saponified aqueous slurry is separated into solid and liquid to obtain CaSO with a purity of 96%. 4 ·2H 2 O, the organic loss of the reaction system is 0.1%.

[0045] Example 2

[0046] First, calcium-magnesium slag containing 90% magnesium hydroxide (main component: Mg 2+ : 37.24%, SO 4 2- :5.58%,Ca 2+ :2.31%) and tap water at a solid-liquid ratio of 1:5, and the slurry is reacted with the P507 to be saponified, and the slurry is added according to the saponification degree of P507 of 0.5mol / L, the reaction temperature is 60℃, the reaction time is 2h, and the reaction is allowed to stand for 3min. The saponified aqueous slurry is discharged from the cone bottom of the reaction device to separate the saponified organic phase from the saponified aqueous slurry. The separated saponified aqueous slurry is separated into solid and liquid to obtain CaSO with a purity of 95%. 4 ·2H 2 O, the organic loss of the reaction system is 0.05%.

[0047] Example 3

[0048] First, a mixture containing 23.93% magnesium hydroxide (main components: magnesium: 9.9%, Ca: 17.14%, SO 4 2- : 45.76%)) and tap water were slurried at a solid-liquid ratio of 1:5, and the slurry was reacted with P507 to be saponified (the slurry was added according to the saponification degree of P507 of 0.5 mol / L), the reaction temperature was 50°C, the reaction time was 1h, and the reaction was allowed to stand for 15min. The saponified aqueous slurry was discharged from the cone bottom of the reaction device to separate the saponified organic phase from the saponified aqueous slurry. The separated saponified aqueous slurry was solid-liquid separated to obtain CaSO with a purity of 99%. 4 ·2H 2 O, the organic loss of the reaction system is 0.1%.

[0049] The calcium-magnesium slag used in this embodiment (SEM image as shown in FIG. Figure 1 As shown, the energy spectrum scan is as follows Figure 2 (shown) comes from the slag formed after the magnesium sulfate wastewater is neutralized with lime.

[0050] The CaSO prepared in this example 4 ·2H 2 The SEM image of O Figure 3 As shown by Figure 3 It can be seen that the magnesium in the magnesium slag has participated in the reaction.

[0051] The CaSO prepared in this example 4 ·2H 2 The energy spectrum of O is shown in the following figure: Figure 4 As shown by Figure 4 It can be seen that the magnesium content in the remaining calcium sulfate after the reaction is low.

[0052] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for recycling magnesium resources in calcium-magnesium slag, characterized in that: The following steps are involved: Mixing magnesium slag with water to prepare slurry to obtain slurry; The slurry is reacted with the P507 to be saponified, and then the saponified aqueous slurry and the saponified organic phase are separated; The saponified aqueous slurry is subjected to solid-liquid separation to obtain calcium sulfate.

2. The method for recycling magnesium resources in calcium-magnesium slag according to claim 1, characterized in that: The content of magnesium hydroxide in the magnesium slag is ≥20wt%.

3. The method for recycling magnesium resources in calcium-magnesium slag according to claim 1, characterized in that: The solid-liquid ratio of the magnesium slag to the water is 1:3-10.

4. The method for recycling magnesium resources in calcium-magnesium slag according to claim 1, characterized in that: The amount of the slurry added is based on the saponification degree of the P507 to be saponified being 0.5 mol / L.

5. The method for recycling magnesium resources in calcium-magnesium slag according to claim 1, characterized in that: The reaction temperature is 30-60°C.

6. The method for recycling magnesium resources in calcium-magnesium slag according to claim 1, characterized in that: The reaction time is 0.1-2h.

7. The method for recycling magnesium resources in calcium-magnesium slag according to claim 1, characterized in that: After the reaction is completed, the step of standing still is also included.

8. The method for recycling magnesium resources in calcium-magnesium slag according to claim 7, characterized in that: The standing time is 3-15 min.

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