Highly active ultrafine composite phase magnesium oxide and its preparation method, applications of composite phase magnesium oxide

Abstract

This invention discloses a highly active ultrafine composite phase magnesium oxide, its preparation method, and its applications. The main components of the highly active ultrafine composite magnesium oxide are magnesium oxide and basic magnesium chloride (Mg). x (OH) y Cl z • nH2O (x: 1~3, y: 1~5, z: 1~4, n: 0~5); Magnesium oxide powder contains a small amount of Mg. x (OH) y Cl z The addition of nH2O, which alters the lattice of magnesium oxide powder, increases the number of active sites in the powder. This enhanced activity plays a crucial role in promoting rapid saponification and phase separation of acidic extractants, reducing the amount of three-phase material, and improving the purity of rare earth products during rare earth extraction and separation.

Description

Technical Field

[0001] This invention relates to the field of rare earth smelting and separation technology, and in particular to a highly active ultrafine composite phase magnesium oxide, its preparation method, and its application. Background Technology

[0002] High-salinity wastewater is a typical example of difficult-to-treat wastewater, characterized by its complex composition and large fluctuations. It mainly originates from industries such as smelting, chemical processing, and dyeing. Direct discharge causes serious environmental pollution and significant waste of water and salt resources. Industrial high-salinity wastewater requires advanced treatment technologies. Traditional methods, such as concentration and crystallization, can achieve water reuse, but they produce solid deposits, most of which are highly soluble. Due to high treatment costs, these deposits cannot be utilized as resources and easily cause secondary pollution.

[0003] A single rare earth chloride solution can be prepared by extraction and separation of mixed rare earth chloride solutions. The organic solvents used in the extraction and separation process typically include liquid ammonia, liquid alkali, calcium oxide, or light-calcined magnesium oxide for saponification. However, the extraction and separation process in rare earth smelting generates a large amount of high-salt wastewater, such as ammonium chloride, sodium chloride, calcium chloride, and magnesium chloride wastewater. Currently, this high-salt wastewater is usually treated at the end of the process, which presents problems such as high treatment costs and difficulties, resulting in the wastewater and its salt components not being recycled. Furthermore, conventional magnesium oxide saponification usually uses light-calcined magnesium oxide, which has low activity, high impurity content, slow reaction rate with the organic phase, and is prone to forming solid three-phase substances, causing organic phase loss. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing highly active ultrafine composite phase magnesium oxide and its application, enabling the recycling of saline wastewater while obtaining highly active magnesium oxide powder. The magnesium oxide powder contains a small amount of Mg(OH)Cl, and the lattice distortion of the magnesium oxide powder increases the number of active sites. Improving the activity of magnesium oxide powder plays an important role in promoting the rapid saponification and phase separation of acidic extractants, reducing three-phase matter, and improving the purity of rare earth products during rare earth extraction and separation.

[0005] To address the aforementioned technical problems, a first aspect of this invention provides a highly active ultrafine composite phase magnesium oxide, wherein the composite phase magnesium oxide comprises: magnesium chloride and basic magnesium chloride (Mg). x (OH) y Cl z ·nH2O, where 0.5≤x≤4, 0.5≤y≤6, 0≤z≤5, 0≤n≤5;

[0006] The composite phase magnesium oxide contains magnesium oxide with a weight percentage of 90 wt% to 98 wt%, and Mg... x(OH) y Cl z The weight percentage of nH2O is 2wt% to 10wt%.

[0007] Furthermore, the iodine uptake value of the composite phase magnesium oxide is 60 mg I2 / g MgO to 170 mg I2 / g MgO;

[0008] The particle size D50 of the composite phase magnesium oxide is 0.2 μm to 1.5 μm, preferably 0.5 μm to 1.0 μm.

[0009] Accordingly, a second aspect of the present invention provides a method for preparing highly active ultrafine composite phase magnesium oxide, which prepares composite phase magnesium oxide from magnesium chloride wastewater, comprising the following steps:

[0010] After the pyrolysis furnace reaches the preset temperature, gas is introduced into the magnesium chloride wastewater to atomize it. The atomized magnesium chloride wastewater is then sprayed into the pyrolysis furnace for reaction. Additives are added to regulate the pyrolysis. The phase composition of the pyrolysis products is controlled by controlling the preset temperature and preset atmosphere of the pyrolysis furnace, resulting in a composite phase of magnesium oxide and hydrogen chloride gas.

[0011] Hydrochloric acid solution is obtained by absorbing the hydrogen chloride gas with water.

[0012] Furthermore, the concentration of magnesium chloride in the high-salt magnesium chloride wastewater of the preset concentration is 200 g / L to 450 g / L, preferably 260 g / L to 380 g / L.

[0013] Furthermore, the preset temperature is 550℃~900℃, preferably 650℃~800℃.

[0014] Furthermore, the preset gas includes at least one of nitrogen, air, and oxygen, preferably nitrogen;

[0015] The inlet flow rate of the preset gas is 20 mL / min to 50 mL / min, preferably 30 mL / min to 40 mL / min.

[0016] Further, the additive includes hydrogen peroxide, in an amount of 0.5–10 wt%, preferably 0.5–5.0 wt%.

[0017] Furthermore, the concentration of the hydrochloric acid solution is 4 mol / L to 7 mol / L, and the purity is 99.00% to 99.99%.

[0018] Accordingly, a third aspect of the present invention provides an application of highly active ultrafine composite phase magnesium oxide in a rare earth extraction and separation process. The composite phase magnesium oxide is used to saponify an acidic organic phase, with the degree of saponification controlled at 0.2 mol / L to 0.54 mol / L. The mixing time of the composite phase magnesium oxide and the acidic organic phase is 3 min to 7 min, and the phase separation time is 1 min to 3 min.

[0019] Further, the acidic organic phase is at least one selected from P507, P204, P229, C272, C301, C302, P227, cycloalkanoic acid, fatty acid, and isomeric acid.

[0020] Furthermore, the concentration of the acidic organic phase is 0.5 mol / L to 1.8 mol / L.

[0021] The above-described technical solutions of the embodiments of the present invention have the following beneficial technical effects:

[0022] While achieving the recycling of saline wastewater, highly active magnesium oxide powder is obtained, which contains a small amount of Mg. x (OH) y Cl z • nH2O, the lattice distortion of magnesium oxide powder, increases the active sites of magnesium oxide powder; improving the activity of magnesium oxide powder plays an important role in promoting the rapid saponification and phase separation of acidic extractants, reducing three-phase matter, and improving the purity of rare earth products during rare earth extraction and separation. Attached Figure Description

[0023] Figure 1 This is a flowchart of the method for preparing highly active ultrafine composite phase magnesium oxide provided in the embodiments of the present invention;

[0024] Figure 2 This is an X-ray diffraction pattern of highly active ultrafine composite magnesium oxide provided in an embodiment of the present invention. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments and the accompanying drawings. It should be understood that these descriptions are merely exemplary and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0026] A first aspect of this invention provides a highly active ultrafine composite phase magnesium oxide, the composite phase magnesium oxide comprising: magnesium chloride and basic magnesium chloride (Mg). x (OH) y Cl z·nH₂O, wherein 0.5≤x≤4, 0.5≤y≤6, 0≤z≤5, 0≤n≤5; wherein the weight percentage of magnesium oxide in the composite phase magnesium oxide is 90wt%~98wt%, and Mg x (OH) y Cl z The weight percentage of nH2O is 2wt% to 10wt%.

[0027] Furthermore, the iodine uptake value of the composite phase magnesium oxide is 60 mg I2 / g MgO to 170 mg I2 / g MgO; the particle size D50 of the composite phase magnesium oxide is 0.2 μm to 1.5 μm, preferably 0.5 μm to 1.0 μm.

[0028] Please refer to Figure 1 The second aspect of this invention provides a method for preparing highly active ultrafine composite phase magnesium oxide, which prepares composite phase magnesium oxide from high-salt magnesium chloride wastewater, including the following steps:

[0029] Step S100: After the pyrolysis furnace reaches the preset temperature, a preset gas is introduced into the magnesium chloride wastewater to atomize it. The atomized magnesium chloride wastewater is then sprayed into the pyrolysis furnace for reaction. Additives are added to regulate the pyrolysis. The phase composition of the pyrolysis products is controlled by controlling the preset temperature and preset atmosphere of the pyrolysis furnace to obtain a composite phase of magnesium oxide and hydrogen chloride gas.

[0030] In step S200, hydrogen chloride gas is absorbed by water to obtain a hydrochloric acid solution.

[0031] Specifically, the concentration of magnesium chloride in the high-salt wastewater is 200 g / L to 450 g / L, preferably 260 g / L to 380 g / L.

[0032] The method for preparing highly active ultrafine composite phase magnesium oxide in this invention utilizes additive-assisted spray pyrolysis technology to pyrolyze magnesium chloride wastewater, thereby preparing composite phase magnesium oxide powder. (See attached image) Figure 2 The peak positions at 36.94°, 42.92°, 62.30°, 74.69°, and 78.63° correspond to the standard PDF card of MgO (PDF#45-0946); the peaks at 11.19°, 16.24°, 25.10°, 30.62°, 32.66°, 34.79°, 36.27°, 44.24°, 57.19°, 60.92°, and 69.63° correspond to the characteristic peaks of basic magnesium chloride. The composite phase magnesium oxide prepared by this invention exhibits high activity, and high-purity hydrochloric acid is obtained simultaneously, achieving full material recycling of the magnesium chloride solution during rare earth extraction and separation.

[0033] Specifically, the preset temperature in the spray pyrolysis method is 550℃~900℃, preferably 650℃~800℃.

[0034] The preset gas for atomization is at least one of nitrogen, air, and oxygen, and the inlet gas flow rate is 20 mL / min to 50 mL / min, preferably 30 mL / min to 40 mL / min.

[0035] In step S200 above, the concentration of the hydrochloric acid solution obtained after absorbing hydrogen chloride gas through water is 4 mol / L to 7 mol / L, and the purity is 99.00% to 99.99%.

[0036] Accordingly, a third aspect of the present invention provides an application of highly active ultrafine composite phase magnesium oxide in rare earth extraction and separation processes. The composite phase magnesium oxide is used to saponify an acidic organic phase, with the degree of saponification controlled at 0.3 mol / L to 0.54 mol / L. The mixing time of the composite phase magnesium oxide and the acidic organic phase is 3 min to 7 min, and the phase separation time is 1 min to 3 min, which significantly shortens the phase separation time and reduces the amount of three-phase material.

[0037] Specifically, the acidic organic phase in the rare earth extraction and separation process is at least one of P507, P204, P229, C272, C301, C302, P227, cycloalkanoic acid, fatty acid, and isomeric acid.

[0038] Furthermore, the concentration of the acidic organic phase is 0.5 mol / L to 1.8 mol / L.

[0039] In the technical solution of this invention, the activity of the composite phase magnesium oxide is characterized by the iodine uptake value determination method described in the HG / T 3928-2012 standard; the higher the iodine uptake value, the higher the activity. Furthermore, the hydrogen chloride gas generated during the preparation of composite phase magnesium oxide powder from magnesium chloride wastewater is absorbed by pure water using the high-purity hydrochloric acid preparation method specified in the HGT 2778-2020 standard. The highly active magnesium oxide and high-purity hydrochloric acid can be recycled for rare earth extraction and separation processes, achieving full recycling of materials from the rare earth extraction and separation process.

[0040] The above technical solution will be further illustrated below with a comparative example and several embodiments:

[0041] Comparative Example 1

[0042] Take 0.126g of industrial lightly calcined magnesium oxide, with an iodine absorption value of 56mg I2 / g MgO and a D50 of 2.73μm, and mix it with 10mL of P507 with a concentration of 1.5mol / L for 5min. The degree of saponification is 0.50mol / L, the phase separation time is 5min, and there are flocculent three-phase substances at the oil-water interface.

[0043] Example 1

[0044] In this embodiment of the invention, the high-salt magnesium chloride wastewater was prepared using simulated wastewater prepared with MgCl2·6H2O. A magnesium chloride solution was prepared at room temperature (25°C) with 2 wt% hydrogen peroxide added. The concentration of MgCl2 in the prepared magnesium chloride solution was measured to be 435 g / L. The pyrolysis furnace was heated to 700°C, and air was introduced to atomize the wastewater at an inlet flow rate of 30 mL / min. The atomized magnesium chloride solution was then sprayed into the furnace for pyrolysis. After pyrolysis, magnesium oxide powder and condensed acid were collected to obtain a highly active ultrafine composite phase magnesium oxide with 92.05 wt% magnesium oxide and 7.53 wt% Mg(OH)Cl. This highly active ultrafine composite phase magnesium oxide had an iodine uptake value of 143.30 mg I2 / g MgO and a D50 of 0.92 μm. Controlling the degree of saponification at 0.50 mol / L, 0.1 g of highly active ultrafine composite magnesium oxide was mixed with 10 mL of 1.5 mol / L P507 for 5 min, and the phase separation time was 1.5 min, with no three-phase material at the oil-water interface. The condensed acid prepared by pyrolysis had a concentration of 4.80 mol / L and a purity of 99.94%.

[0045] Example 2

[0046] In this embodiment of the invention, the high-salt magnesium chloride wastewater was simulated wastewater prepared using MgCl2·6H2O. A magnesium chloride solution was prepared at room temperature (25°C), and the concentration of MgCl2 in the prepared solution was measured to be 300 g / L. The pyrolysis furnace was heated to 700°C, and then the atomized magnesium chloride solution was sprayed into the furnace for pyrolysis. After pyrolysis, magnesium oxide powder and condensed acid were collected, yielding a highly active ultrafine composite phase magnesium oxide with 91.56 wt% magnesium oxide and 8.04 wt% Mg(OH)Cl. This highly active ultrafine composite phase magnesium oxide had an iodine uptake value of 135.36 mg I2 / g MgO and a D50 of 0.56 μm. Controlling the degree of saponification at 0.50 mol / L, 0.1 g of the highly active ultrafine composite phase magnesium oxide was mixed with 10 mL of 1.5 mol / L P507 for 5 min. The phase separation time was 1.5 min, and no three-phase material was observed at the oil-water interface. The condensed acid prepared by pyrolysis has a concentration of 6.76 mol / L and a purity of 99.23%.

[0047] Example 3

[0048] In this embodiment of the invention, the high-salt magnesium chloride wastewater was simulated wastewater prepared using MgCl2·6H2O. A magnesium chloride solution was prepared at room temperature (25°C), and the concentration of MgCl2 in the prepared solution was measured to be 300 g / L. The pyrolysis furnace was heated to 750°C, and then the atomized magnesium chloride solution was sprayed into the furnace for pyrolysis. After pyrolysis, magnesium oxide powder and condensed acid were collected, yielding a highly active ultrafine composite phase magnesium oxide with 93.24 wt% magnesium oxide and 6.24 wt% Mg(OH)Cl. This highly active ultrafine composite phase magnesium oxide had an iodine uptake value of 148.97 mg I2 / g MgO and a D50 of 0.52 μm. Controlling the degree of saponification at 0.36 mol / L, 0.072 g of the highly active ultrafine composite phase magnesium oxide was mixed with 10 mL of 1.0 mol / L naphthenic acid for 4 min. The phase separation time was 1.4 min, and no three-phase material was observed at the oil-water interface. The condensed acid prepared by pyrolysis has a concentration of 6.52 mol / L and a purity of 99.86%.

[0049] Example 4

[0050] In this embodiment of the invention, the high-salt magnesium chloride wastewater was simulated wastewater prepared using MgCl2·6H2O. A magnesium chloride solution was prepared at room temperature (25°C), and the concentration of MgCl2 in the prepared solution was measured to be 300 g / L. The pyrolysis furnace was heated to 770°C, and then the atomized magnesium chloride solution was sprayed into the furnace for pyrolysis. After pyrolysis, magnesium oxide powder and condensed acid were collected, yielding a highly active ultrafine composite phase magnesium oxide with 94.79 wt% magnesium oxide and 5.03 wt% Mg(OH)Cl. This highly active ultrafine composite phase magnesium oxide had an iodine uptake value of 156.46 mg I2 / g MgO and a D50 of 0.51 μm. Controlling the degree of saponification at 0.36 mol / L, 0.072 g of the highly active ultrafine composite phase magnesium oxide was mixed with 10 mL of 1.0 mol / L P2O4 for 6 min. The phase separation time was 1.3 min, and no three-phase material was observed at the oil-water interface. The condensed acid prepared by pyrolysis has a concentration of 6.34 mol / L and a purity of 99.35%.

[0051] Example 5

[0052] In this embodiment of the invention, the high-salt magnesium chloride wastewater was simulated wastewater prepared using MgCl2·6H2O. A magnesium chloride solution was prepared at room temperature (25°C), and the concentration of MgCl2 in the prepared solution was measured to be 300 g / L. The pyrolysis furnace was heated to 790°C, and then the atomized magnesium chloride solution was sprayed into the furnace for pyrolysis. After pyrolysis, magnesium oxide powder and condensed acid were collected, yielding a highly active ultrafine composite phase magnesium oxide with 96.31 wt% magnesium oxide and 3.22 wt% Mg(OH)Cl. This highly active ultrafine composite phase magnesium oxide had an iodine uptake value of 165.55 mg I2 / g MgO and a D50 of 0.49 μm. Controlling the degree of saponification at 0.36 mol / L, 0.072 g of the highly active ultrafine composite phase magnesium oxide was mixed with 10 mL of 1 mol / L C272 for 6 min. The phase separation time was 1.1 min, and no three-phase material was observed at the oil-water interface. The condensed acid prepared by pyrolysis has a concentration of 6.15 mol / L and a purity of 99.26%.

[0053] Example 6

[0054] In this embodiment of the invention, the high-salt magnesium chloride wastewater was simulated wastewater prepared using MgCl2·6H2O. A magnesium chloride solution was prepared at room temperature (25°C), and the concentration of MgCl2 in the prepared solution was measured to be 300 g / L. The pyrolysis furnace was heated to 800°C, and then the atomized magnesium chloride solution was sprayed into the furnace for pyrolysis. After pyrolysis, magnesium oxide powder and condensed acid were collected, yielding a highly active ultrafine composite phase magnesium oxide with 97.54 wt% magnesium oxide and 2.27 wt% Mg(OH)Cl. This highly active ultrafine composite phase magnesium oxide had an iodine uptake value of 143.57 mg I2 / g MgO and a D50 of 0.50 μm. Controlling the degree of saponification at 0.50 mol / L, 0.1 g of the highly active ultrafine composite phase magnesium oxide was mixed with 10 mL of 1.5 mol / L P227 for 6 min. The phase separation time was 1.2 min, and no three-phase material was observed at the oil-water interface. The condensed acid prepared by pyrolysis has a concentration of 5.89 mol / L and a purity of 99.57%.

[0055] Example 7

[0056] In this embodiment of the invention, the high-salt magnesium chloride wastewater was simulated wastewater prepared using MgCl2·6H2O. A magnesium chloride solution was prepared at room temperature (25°C), and the concentration of MgCl2 in the prepared solution was measured to be 350 g / L. The pyrolysis furnace was heated to 790°C, and then the atomized magnesium chloride solution was sprayed into the furnace for pyrolysis. After pyrolysis, magnesium oxide powder and condensed acid were collected, yielding a highly active ultrafine composite phase magnesium oxide with 92.31 wt% magnesium oxide and 6.29 wt% Mg(OH)Cl. This highly active ultrafine composite phase magnesium oxide had an iodine uptake value of 138.77 mg I2 / g MgO and a D50 of 0.79 μm. Controlling the degree of saponification at 0.38 mol / L, 0.076 g of the highly active ultrafine composite phase magnesium oxide was mixed with 10 mL of 1.2 mol / L P507 for 5 min. The phase separation time was 1.4 min, and no three-phase material was observed at the oil-water interface. The condensed acid prepared by pyrolysis has a concentration of 4.98 mol / L and a purity of 99.88%.

[0057] Example 8

[0058] In this embodiment of the invention, the high-salt magnesium chloride wastewater was simulated wastewater prepared using MgCl2·6H2O. A magnesium chloride solution was prepared at room temperature (25°C), and the concentration of MgCl2 in the prepared solution was measured to be 380 g / L. The pyrolysis furnace was heated to 790°C, and then the atomized magnesium chloride solution was sprayed into the furnace for pyrolysis. After pyrolysis, magnesium oxide powder and condensed acid were collected, yielding a highly active ultrafine composite phase magnesium oxide with 93.66 wt% magnesium oxide and 5.92 wt% Mg(OH)Cl. This highly active ultrafine composite phase magnesium oxide had an iodine uptake value of 135.63 mg I2 / g MgO and a D50 of 0.63 μm. Controlling the degree of saponification at 0.45 mol / L, 0.09 g of the highly active ultrafine composite phase magnesium oxide was mixed with 10 mL of 1.5 mol / L P507 for 5 min. The phase separation time was 1.6 min, and no three-phase material was observed at the oil-water interface. The condensed acid prepared by pyrolysis has a concentration of 6.02 mol / L and a purity of 99.32%.

[0059] Example 9

[0060] In this embodiment of the invention, the high-salt magnesium chloride wastewater is a simulated wastewater prepared using MgCl2·6H2O. A magnesium chloride solution was prepared at room temperature (25°C), and the concentration of MgCl2 in the prepared solution was measured to be 380 g / L. The pyrolysis furnace was heated to 800°C, and then the atomized magnesium chloride solution was sprayed into the furnace for pyrolysis. After pyrolysis, magnesium oxide powder and condensed acid were collected to obtain a highly active ultrafine composite phase magnesium oxide, in which magnesium oxide accounted for 94.19 wt% and Mg(OH)Cl accounted for 4.94 wt%. This highly active ultrafine composite phase magnesium oxide had an iodine uptake value of 116.59 mg I2 / g MgO and a D50 of 0.75 μm. Controlling the degree of saponification at 0.40 mol / L, 0.8 g of highly active ultrafine composite magnesium oxide was mixed with 10 mL of a 1.2 mol / L P204-P507 mixed extractant for 6 min. The phase separation time was 1.5 min, and no three-phase material was observed at the oil-water interface. The condensed acid prepared by pyrolysis had a concentration of 6.95 mol / L and a purity of 99.21%.

[0061] Example 10

[0062] In this embodiment of the invention, the high-salt magnesium chloride wastewater was simulated wastewater prepared using MgCl2·6H2O. A magnesium chloride solution was prepared at room temperature (25°C), and the concentration of MgCl2 in the prepared solution was measured to be 420 g / L. The pyrolysis furnace was heated to 760°C, and then the atomized magnesium chloride solution was sprayed into the furnace for pyrolysis. After pyrolysis, magnesium oxide powder and condensed acid were collected, yielding a highly active ultrafine composite phase magnesium oxide with 92.35 wt% magnesium oxide and 6.98 wt% Mg(OH)Cl. This highly active ultrafine composite phase magnesium oxide had an iodine uptake value of 98.25 mg I2 / g MgO and a D50 of 0.99 μm. Controlling the degree of saponification at 0.50 mol / L, 0.1 g of the highly active ultrafine composite phase magnesium oxide was mixed with 10 mL of 1.5 mol / L P507 for 6 min. The phase separation time was 1.6 min, and no three-phase material was observed at the oil-water interface. The condensed acid prepared by pyrolysis has a concentration of 7.94 mol / L and a purity of 99.47%.

[0063] Example 11

[0064] In this embodiment of the invention, the high-salt magnesium chloride wastewater was simulated wastewater prepared using MgCl2·6H2O. A magnesium chloride solution was prepared at room temperature (25°C), and the concentration of MgCl2 in the prepared solution was measured to be 450 g / L. The pyrolysis furnace was heated to 800°C, and then the atomized magnesium chloride solution was sprayed into the furnace for pyrolysis. After pyrolysis, magnesium oxide powder and condensed acid were collected, yielding a highly active ultrafine composite phase magnesium oxide with 96.42 wt% magnesium oxide and 3.16 wt% Mg(OH)Cl. This highly active ultrafine composite phase magnesium oxide had an iodine uptake value of 132 mg I2 / g MgO and a D50 of 1.35 μm. Controlling the degree of saponification at 0.24 mol / L, 0.048 g of the highly active ultrafine composite phase magnesium oxide was mixed with 10 mL of 0.8 mol / L P507 for 6 min. The phase separation time was 1.7 min, and no three-phase material was observed at the oil-water interface. The condensed acid prepared by pyrolysis has a concentration of 7.96 mol / L and a purity of 99.68%.

[0065] Example 12

[0066] In this embodiment of the invention, the high-salt magnesium chloride wastewater was simulated wastewater prepared using MgCl2·6H2O. A magnesium chloride solution was prepared at room temperature (25°C), and the concentration of MgCl2 in the prepared solution was measured to be 330 g / L. The pyrolysis furnace was heated to 650°C, and then the atomized magnesium chloride solution was sprayed into the furnace for pyrolysis. After pyrolysis, magnesium oxide powder and condensed acid were collected, yielding a highly active ultrafine composite phase magnesium oxide with 92.21 wt% magnesium oxide and 6.79 wt% Mg(OH)Cl. This highly active ultrafine composite phase magnesium oxide had an iodine uptake value of 89.83 mg I2 / g MgO and a D50 of 1.47 μm. Controlling the degree of saponification at 0.50 mol / L, 0.1 g of the highly active ultrafine composite phase magnesium oxide was mixed with 10 mL of 1.5 mol / L C301 for 6 min. The phase separation time was 2 min, and no three-phase material was observed at the oil-water interface. The condensed acid prepared by pyrolysis has a concentration of 4.26 mol / L and a purity of 99.52%.

[0067] Example 13

[0068] In this embodiment of the invention, the high-salt magnesium chloride wastewater was simulated wastewater prepared using MgCl2·6H2O. A magnesium chloride solution was prepared at room temperature (25°C), and the concentration of MgCl2 in the prepared solution was measured to be 250 g / L. The pyrolysis furnace was heated to 600°C, and then the atomized magnesium chloride solution was sprayed into the furnace for pyrolysis. After pyrolysis, magnesium oxide powder and condensed acid were collected, yielding a highly active ultrafine composite phase magnesium oxide with 91.32 wt% magnesium oxide and 7.58 wt% Mg(OH)Cl. This highly active ultrafine composite phase magnesium oxide had an iodine uptake value of 66.41 mg I2 / g MgO and a D50 of 1.33 μm. Controlling the degree of saponification at 0.27 mol / L, 0.054 g of the highly active ultrafine composite phase magnesium oxide was mixed with 10 mL of 0.9 mol / L C3O2 for 7 min. The phase separation time was 1.9 min, and no three-phase material was observed at the oil-water interface. The condensed acid prepared by pyrolysis has a concentration of 4.59 mol / L and a purity of 99.21%.

[0069] Example 14

[0070] In this embodiment of the invention, the high-salt magnesium chloride wastewater was simulated wastewater prepared using MgCl2·6H2O. A magnesium chloride solution was prepared at room temperature (25°C), and the concentration of MgCl2 in the prepared solution was measured to be 280 g / L. The pyrolysis furnace was heated to 550°C, and then the atomized magnesium chloride solution was sprayed into the furnace for pyrolysis. After pyrolysis, magnesium oxide powder and condensed acid were collected, yielding a highly active ultrafine composite phase magnesium oxide with 90.53 wt% magnesium oxide and 7.47 wt% Mg(OH)Cl. This highly active ultrafine composite phase magnesium oxide had an iodine uptake value of 85.32 mg I2 / g MgO and a D50 of 1.26 μm. Controlling the degree of saponification at 0.50 mol / L, 0.1 g of the highly active ultrafine composite phase magnesium oxide was mixed with 10 mL of 1.5 mol / L P229 for 6 min. The phase separation time was 2 min, and no three-phase material was observed at the oil-water interface. The condensed acid prepared by pyrolysis has a concentration of 4.89 mol / L and a purity of 99.54%.

[0071] Example 15

[0072] In this embodiment of the invention, the high-salt magnesium chloride wastewater was simulated wastewater prepared using MgCl2·6H2O. A magnesium chloride solution was prepared at room temperature (25°C), and the concentration of MgCl2 in the prepared solution was measured to be 300 g / L. The pyrolysis furnace was heated to 670°C, and then the atomized magnesium chloride solution was sprayed into the furnace for pyrolysis. After pyrolysis, magnesium oxide powder and condensed acid were collected, yielding a highly active ultrafine composite phase magnesium oxide with 91.58 wt% magnesium oxide and 6.42 wt% Mg(OH)Cl. This highly active ultrafine composite phase magnesium oxide had an iodine uptake value of 108.97 mg I2 / g MgO and a D50 of 0.94 μm. Controlling the degree of saponification at 0.50 mol / L, 0.1 g of the highly active ultrafine composite phase magnesium oxide was mixed with 10 mL of 1.5 mol / L P507 for 7 min. The phase separation time was 1.8 min, and no three-phase material was observed at the oil-water interface. The condensed acid prepared by pyrolysis has a concentration of 5.35 mol / L and a purity of 99.67%.

[0073] Example 16

[0074] In this embodiment of the invention, the high-salt magnesium chloride wastewater was simulated wastewater prepared using MgCl2·6H2O. A magnesium chloride solution was prepared at room temperature (25°C), and the concentration of MgCl2 in the prepared solution was measured to be 300 g / L. The pyrolysis furnace was heated to 720°C, and then the atomized magnesium chloride solution was sprayed into the furnace for pyrolysis. After pyrolysis, magnesium oxide powder and condensed acid were collected to obtain a highly active ultrafine composite phase magnesium oxide with 92.25 wt% magnesium oxide and 6.75 wt% Mg(OH)Cl. This highly active ultrafine composite phase magnesium oxide had an iodine uptake value of 133.68 mg I2 / g MgO and a D50 of 0.77 μm. Controlling the degree of saponification at 0.50 mol / L, 0.1 g of the highly active ultrafine composite phase magnesium oxide was mixed with 10 mL of 1.5 mol / L P507 for 6 min. The phase separation time was 1.5 min, and no three-phase material was observed at the oil-water interface. The condensed acid prepared by pyrolysis has a concentration of 5.87 mol / L and a purity of 99.33%.

[0075] The specific implementation steps in Examples 2-16 are the same as those in Example 1, except that the specific implementation parameters and the detection indicators of the prepared composite phase magnesium oxide are different, as detailed in Table 1.

[0076] Table 1

[0077]

[0078]

[0079]

[0080] Specifically, the chemical reagents used in this invention are analytical grade reagents, and the activity of the composite phase magnesium oxide obtained in the examples was measured by the iodine uptake method.

[0081] This invention aims to protect a highly active ultrafine composite phase magnesium oxide and its preparation method, as well as its applications. The composite phase magnesium oxide is prepared from high-salt magnesium chloride wastewater. The preparation method includes the following steps: decomposing a pre-set concentration of high-salt magnesium chloride wastewater into composite phase magnesium oxide and hydrogen chloride gas using a spray pyrolysis method; controlling the content of the composite phase by controlling the temperature and inlet gas flow rate to ensure high activity of the powder; and absorbing the hydrogen chloride gas with water to obtain a hydrochloric acid solution. The above technical solution has the following advantages:

[0082] While achieving the recycling of saline wastewater, highly active magnesium oxide powder is obtained. The magnesium oxide powder contains a small amount of Mg(OH)Cl, and the lattice distortion of the magnesium oxide powder increases the active sites. Improving the activity of magnesium oxide powder plays an important role in promoting the rapid saponification and phase separation of acidic extractants, reducing three-phase matter, and improving the purity of rare earth products during rare earth extraction and separation.

[0083] It should be understood that the specific embodiments described above are merely illustrative or explanatory of the principles of the invention and do not constitute a limitation thereof. Therefore, any modifications, equivalent substitutions, improvements, etc., made without departing from the spirit and scope of the invention should be included within the protection scope of the invention. Furthermore, the appended claims are intended to cover all variations and modifications falling within the scope and boundaries of the appended claims, or equivalent forms of such scope and boundaries.

Claims

1. A highly active ultrafine composite phase magnesium oxide, characterized in that, The composite phase magnesium oxide comprises: magnesium oxide and basic magnesium chloride (Mg). x (OH) y Cl z ·nH2O, where 0.5≤x≤4, 0.5≤y≤6, 0<z≤5, 0≤n≤5; The composite phase magnesium oxide contains magnesium oxide at a weight percentage of 90 wt% to 98 wt%, and Mg... x (OH) y Cl z The weight percentage of nH2O is 2 wt% to 10 wt%, and the iodine uptake value of the composite phase magnesium oxide is 60 mg I2 / g MgO to 170 mg I2 / g MgO.

2. The highly active ultrafine composite phase magnesium oxide according to claim 1, characterized in that, The particle size D50 of the composite phase magnesium oxide is 0.2 μm to 1.5 μm.

3. The highly active ultrafine composite phase magnesium oxide according to claim 2, characterized in that, The particle size D50 of the composite phase magnesium oxide is 0.5 μm to 1.0 μm.

4. A method for preparing highly active ultrafine composite phase magnesium oxide, characterized in that, The method for preparing highly active ultrafine composite phase magnesium oxide as described in any one of claims 1-3 includes the following steps: After the pyrolysis furnace reaches the preset temperature, a preset gas is introduced into the magnesium chloride wastewater to atomize it. The atomized magnesium chloride wastewater is then sprayed into the pyrolysis furnace for reaction. Additives are added to regulate the pyrolysis. The phase composition of the pyrolysis products is controlled by controlling the preset temperature and preset atmosphere of the pyrolysis furnace, resulting in a composite phase of magnesium oxide and hydrogen chloride gas. Hydrochloric acid solution is obtained by absorbing the hydrogen chloride gas with water.

5. The method for preparing highly active ultrafine composite phase magnesium oxide according to claim 4, characterized in that, The concentration of magnesium chloride in the magnesium chloride wastewater is 200 g / L to 450 g / L.

6. The method for preparing highly active ultrafine composite phase magnesium oxide according to claim 5, characterized in that, The concentration of magnesium chloride in the magnesium chloride wastewater is 260 g / L to 380 g / L.

7. The method for preparing highly active ultrafine composite phase magnesium oxide according to claim 4, characterized in that, The preset temperature is 550 ℃~900 ℃.

8. The method for preparing highly active ultrafine composite phase magnesium oxide according to claim 7, characterized in that, The preset temperature is 650 ℃~800 ℃.

9. The method for preparing highly active ultrafine composite phase magnesium oxide according to claim 4, characterized in that, The preset gas includes at least one of nitrogen, air, and oxygen. The inlet flow rate of the preset gas is 20 mL / min to 50 mL / min.

10. The method for preparing highly active ultrafine composite phase magnesium oxide according to claim 9, characterized in that, The preset gas is nitrogen; The inlet flow rate of the preset gas is 30 mL / min ~ 40 mL / min.

11. The method for preparing highly active ultrafine composite phase magnesium oxide according to claim 4, characterized in that, The additives include: hydrogen peroxide; The hydrogen peroxide content is 0.5 wt% to 10 wt%.

12. The method for preparing highly active ultrafine composite phase magnesium oxide according to claim 11, characterized in that, The hydrogen peroxide content is 0.5 wt% to 5.0 wt%.

13. The method for preparing highly active ultrafine composite phase magnesium oxide according to any one of claims 4-12, characterized in that, The concentration of the hydrochloric acid solution is 4 mol / L to 7 mol / L, and the purity is 99.00% to 99.99%.

14. An application of a highly active ultrafine composite phase magnesium oxide, characterized in that, This method is applied to the rare earth extraction and separation process, using the highly active ultrafine composite phase magnesium oxide as described in any one of claims 1-3 to saponify the acidic organic phase, controlling the degree of saponification to be 0.20 mol / L ~ 0.54 mol / L, the mixing time of the composite phase magnesium oxide and the acidic organic phase to be 3 min ~ 7 min, and the phase separation time to be 1 min ~ 3 min.

15. The application of the highly active ultrafine composite phase magnesium oxide according to claim 14, characterized in that, The acidic organic phase is at least one of P507, P204, P229, C272, C301, C302, P227, cycloalkanoic acid, fatty acid and isomeric acid; The concentration of the acidic organic phase is 0.5 mol / L to 1.8 mol / L.

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