Method for extracting magnesium from serpentine

Abstract

A method for extracting magnesium from serpentine, comprising: introducing a feed gas containing carbon dioxide gas into a buffer solution to obtain a buffer solution containing nano- and micro-scale carbon dioxide bubbles, wherein the particle size of the nano- and micro-scale carbon dioxide bubbles is ≤100 μm; crushing the serpentine to obtain serpentine fragments; subjecting the serpentine fragments and the buffer solution containing nano- and micro-scale carbon dioxide bubbles to a carbonation reaction to obtain a mixed suspension containing a magnesium bicarbonate leachate; and performing solid-liquid separation on the mixed suspension containing the magnesium bicarbonate leachate to obtain a magnesium-containing liquid phase.

Description

A method for extracting magnesium from serpentine

[0001] Cross-references to related applications

[0002] This application claims priority to Chinese patent application No. 202510347010.0, filed on March 24, 2025, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates to the field of waste recycling technology, and in particular to a method for extracting magnesium from serpentine. Background Technology

[0004] Serpentine is abundant in mineral resources and is generally found in association with or associated with various minerals such as iron, cobalt, nickel, and chromium. The main chemical components of serpentine are SiO2, MgO, Fe2O3, and nickel oxides. Serpentine typically exists as hydrated magnesium silicate, which contributes to its relatively stable crystal structure. In industry, serpentine is widely used in the production of fertilizers, refractory materials, and other industrial products. However, serpentine has significant shortcomings in the enrichment of valuable elements and the effective utilization of all its components, leading to the frequent disposal of large quantities of underutilized serpentine as tailings. The utilization of these serpentine tailings faces numerous challenges, including low value, limited market demand, difficulty in large-scale disposal, and difficulty in achieving large-scale application. Therefore, it is urgent to explore new methods for serpentine disposal.

[0005] Currently, extracting elements such as magnesium, silicon, and iron from serpentine typically requires treatment with high-concentration strong acid or alkali media. For example, concentrated sulfuric acid or ammonium sulfate is roasted with serpentine at high temperatures, and the roasted product is then extracted and recovered by water leaching. However, this recovery method has many drawbacks: firstly, the magnesium extraction rate is less than 90%, and magnesium and silicon exhibit poor selectivity in these strong acid or alkali media, requiring multiple purification processes for the magnesium leachate; secondly, this extraction method generates large quantities of waste acid or alkali solutions, the treatment of which is costly, and the treatment process places high demands on the corrosion resistance of the equipment, making the widespread adoption of this extraction method extremely difficult.

[0006] Currently, carbonation is the primary method for extracting magnesium from magnesium-containing minerals. Carbonation offers advantages such as mild reaction conditions, high magnesium selectivity, and high purity leachate. However, carbonation under normal pressure conditions struggles to break down the phase structure of serpentine; therefore, it typically requires high-pressure conditions. High-pressure carbonation converts magnesium silicate into magnesium bicarbonate solution through a pressurized carbonation reaction, thereby enabling the recovery of magnesium from serpentine. However, pressurized carbonation increases the difficulty of magnesium extraction from serpentine, and the magnesium extraction rate is relatively low. Summary of the Invention

[0007] One or more embodiments of this disclosure provide a method for extracting magnesium from serpentine, which can improve the magnesium extraction rate from serpentine.

[0008] In a first aspect, embodiments of this disclosure provide a method for extracting magnesium from serpentine, wherein the serpentine contains magnesium. The method includes: passing a raw material gas containing carbon dioxide gas into a buffer solution to obtain a buffer solution containing nano-micro carbon dioxide bubbles, wherein the particle size of the nano-micro carbon dioxide bubbles is ≤100μm; crushing the serpentine to obtain serpentine fragments; performing a carbonization reaction between the serpentine fragments and the buffer solution containing nano-micro carbon dioxide bubbles to obtain a mixed suspension containing magnesium bicarbonate leachate; and performing solid-liquid separation on the mixed suspension containing magnesium bicarbonate leachate to obtain a magnesium-containing liquid phase. Attached Figure Description

[0009] The accompanying drawings, which are incorporated in and form a part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure.

[0010] To more clearly illustrate the technical solutions in the embodiments of this disclosure or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0011] Figure 1 shows a schematic flowchart of a method for extracting magnesium from serpentine according to some embodiments of the present disclosure.

[0012] Figure 2 shows a detailed flowchart of a method for extracting magnesium from serpentine according to some embodiments of the present disclosure. Embodiments of the present invention

[0013] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this disclosure. Based on the embodiments of this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[0014] Various embodiments of this disclosure may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of this disclosure; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range; for example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range such as 1, 2, 3, 4, 5, and 6, regardless of the range; furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the range referred to.

[0015] In this document, terms such as “comprising” mean “including but not limited to”. Relational terms such as “first” and “second” are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. “And / or” describes the relationship between related objects, indicating that there can be three relationships, for example, A and / or B can mean: A alone, A and B simultaneously, or B alone; where A and B can be singular or plural. “At least one” means one or more, “more” means two or more; “at least one,” “at least one of the following,” or similar expressions refer to any combination of these items, including any combination of single or plural items; for example, “at least one of a, b, or c,” or “at least one of a, b, and c,” can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple. "Parts representation" such as parts by weight or parts by mass indicates the proportional relationship between components. In the proportional relationships discussed in this article, the parameters that need to be described by proportion should be understood as the first term of the proportion in the order of description, and the proportion figures should be understood as the second term of the proportion. For example, if the mass ratio of substance A, substance B, and substance C is 1:2:3, then substances A, B, and C should correspond one-to-one with the proportion figures in the proportion in the order of description, that is, the mass of substance A: the mass of substance B: the mass of substance C = 1:2:3.

[0016] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this article can be purchased from the market or prepared by existing methods.

[0017] Figure 1 illustrates, by way of example, a process flow diagram of a method for extracting magnesium from serpentine according to some embodiments of the present disclosure;

[0018] As shown in Figure 1, this disclosure provides a method for extracting magnesium from serpentine, which contains magnesium. The method includes:

[0019] S1. Pass the raw material gas containing carbon dioxide gas into the buffer solution to obtain a buffer solution containing nano-sized carbon dioxide bubbles, wherein the particle size of the nano-sized carbon dioxide bubbles is ≤100μm.

[0020] S2. Crush the serpentine to obtain serpentine fragments;

[0021] S3. The serpentine fragments and a buffer solution containing nano- and micro-carbon dioxide bubbles are subjected to a carbonation reaction to obtain a mixed suspension containing magnesium bicarbonate leachate; and,

[0022] S4. The mixed suspension containing magnesium bicarbonate leachate is subjected to solid-liquid separation to obtain a magnesium-containing liquid phase.

[0023] It should be noted that the introduction of raw material gas containing carbon dioxide can be accomplished using a nano-micro bubble generator.

[0024] It should be noted that the buffer particles used to prepare this buffer solution (also called buffer solution) can be alkaline media containing sodium salts, alkaline media containing ammonium salts, or alkaline media containing potassium salts.

[0025] It should be noted that the raw material gas containing carbon dioxide can be prepared by capturing CO2 from industrial waste gas.

[0026] It should be noted that when serpentine contains silicon and iron, in addition to producing a magnesium-containing liquid phase, a silica-containing tailings may also be generated during the solid-liquid separation stage. The tailings can be subsequently separated by magnetic separation to obtain iron concentrate and silica powder.

[0027] It should be noted that the method for extracting magnesium from serpentine provided in this disclosure has the following advantages.

[0028] 1. Synergistic enhancement of physical fragmentation and cavitation effects

[0029] (1) Bubble cavitation effect of nano-carbon dioxide bubbles: By controlling the particle size of carbon dioxide bubbles to below 100 μm, the local shock wave generated when the carbon dioxide bubbles break can penetrate the gaps in the serpentine lattice and destroy the covalent bond structure of silicon-oxygen tetrahedrons and magnesium-oxygen octahedrons in serpentine, making magnesium ions easier to dissolve.

[0030] (2) Dynamic shearing effect: The microjet velocity generated by the cavitation effect of carbon dioxide bubbles can reach more than 100 m / s. This microjet velocity can form a continuous shearing effect on the surface of serpentine particles, thereby accelerating the peeling of magnesium ions from the serpentine surface. In addition, this microjet velocity can also destroy the encapsulation effect of silica on magnesium, thereby accelerating the dissolution of magnesium.

[0031] 2. Reaction kinetics optimization

[0032] (1) Electro-adsorption mechanism: The zeta potential (ζ, also known as electro-electric potential or electro-electric potential) on the surface of nano-carbon dioxide bubbles can reach -30mV to -50mV, which allows the nano-carbon dioxide bubbles themselves to interact with the positively charged magnesium ions (Mg ions) in serpentine. 2+ This forms a strong electrostatic adsorption effect, thereby improving the interaction between nano- and micro-carbon dioxide bubbles and Mg. 2+ The probability of contact.

[0033] (2) Reaction environment control: During the process of introducing serpentine fragments into the buffer solution containing nano-carbon dioxide bubbles, a stable alkaline environment system will be formed. In this alkaline environment, the nano-carbon dioxide bubbles dissolve to produce bicarbonate ions (HCO3-). - The generated bicarbonate ions then combine with magnesium ions dissolved from the serpentine fragments to form a stable magnesium bicarbonate complex Mg(HCO3)2. In addition, this alkaline environment can inhibit the dissolution of silicon components in the serpentine and the formation of viscous silica gel, thereby avoiding passivation caused by silica gel coating on the surface of the reaction particles.

[0034] In summary, this disclosure provides a method for extracting magnesium from serpentine. This method innovatively mixes nano-carbon dioxide bubbles with serpentine fragments based on the unique physicochemical properties of nano-carbon dioxide bubbles. By utilizing mechanical stirring to activate the carbonization reaction raw material (serpentine) (i.e., carbonization reaction activation) and the synergistic effect of nano-carbon dioxide bubbles, the phase structure of serpentine can be effectively broken down, promoting a carbonization reaction between magnesium in the serpentine and nano-carbon dioxide bubbles to form a magnesium bicarbonate complex. The formed magnesium bicarbonate complex enters the liquid phase, thereby significantly increasing the magnesium leaching rate from serpentine and achieving magnesium ion extraction from serpentine under mild conditions. Furthermore, the synergistic effect of carbonization reaction activation and nano-carbon dioxide bubbles can improve the selectivity of magnesium and silicon in serpentine, thereby improving the purity of the magnesium leachate from serpentine. In addition, after magnesium extraction, the silicon component in serpentine is converted into silicon dioxide and enters the waste residue. The waste residue can be processed by magnetic separation to obtain iron concentrate and silica powder, and to achieve efficient separation of iron concentrate and silica. Ultimately, this will enable efficient magnesium extraction from serpentine and simultaneous comprehensive utilization of valuable components such as iron and silicon in serpentine.

[0035] In some alternative embodiments, the nano- and micro-carbon dioxide bubbles include fine-particle carbon dioxide bubbles. The volume of the fine-particle carbon dioxide bubbles is less than or equal to 50% of the total volume of the nano- and micro-carbon dioxide bubbles. The particle size of the fine-particle carbon dioxide bubbles is ≤1 μm.

[0036] In some embodiments, the nano-carbon dioxide bubbles may include fine-particle carbon dioxide bubbles. The volume of the fine-particle carbon dioxide bubbles is greater than or equal to 50% of the total volume of the nano-carbon dioxide bubbles, and the particle size of the fine-particle carbon dioxide bubbles is ≤1 μm. This particle size range (≤1 μm) and volume percentage range (≥50%) ensure that the majority of the nano-carbon dioxide bubbles are fine-particle carbon dioxide bubbles. These fine-particle carbon dioxide bubbles can be stably present in the buffer solution, thereby facilitating sufficient binding between the nano-carbon dioxide bubbles and magnesium ions in serpentine during the subsequent carbonization reaction stage, thereby improving the magnesium extraction rate from serpentine.

[0037] The volume of fine-particle carbon dioxide bubbles can be 10%, 20%, 30%, 40%, or 50% of the total volume of nano- or micro-sized carbon dioxide bubbles.

[0038] It should be noted that the volume of fine-particle carbon dioxide bubbles is greater than or equal to 50% of the total volume of nano-sized carbon dioxide bubbles. This allows the fine-particle carbon dioxide bubbles to be stored in the buffer solution for several hours or even days, avoiding gas escape caused by the fusion and rupture of conventional bubbles during the rising process. This facilitates the full combination between the nano-sized carbon dioxide bubbles and the magnesium ions dissolved in serpentine during the subsequent carbonization reaction stage, ultimately improving the magnesium extraction rate from serpentine.

[0039] In some alternative implementations, the particle size of the nano-carbon dioxide bubbles is 0.1 μm to 100 μm.

[0040] In some embodiments, the particle size of the nano-carbon dioxide bubbles can be from 0.1 μm to 100 μm. This particle size range allows the nano-carbon dioxide bubbles to have a sufficiently small size. Sufficiently small nano-carbon dioxide bubbles can remain stable in the buffer solution for hours or even days, facilitating sufficient binding between the nano-carbon dioxide bubbles and magnesium ions in serpentine during the subsequent carbonization reaction stage, thereby improving the magnesium extraction rate from serpentine.

[0041] The particle size of nano-carbon dioxide bubbles can be 0.1μm, 0.2μm, 0.3μm, 0.4μm, 0.5μm, 1.0μm, 2.0μm, 3.0μm, 4.0μm, 5.0μm, 10.0μm, 20.0μm, 30.0μm, 40.0μm, 50.0μm, 60.0μm, 70.0μm, 80.0μm, 90.0μm or 100.0μm.

[0042] In some optional implementations, the volume of carbon dioxide gas in the feed gas is greater than or equal to 5% of the total volume of the feed gas.

[0043] In some embodiments, the volume of carbon dioxide gas in the feed gas is greater than or equal to 5% of the total volume of the feed gas. This volume ratio ensures that there is a sufficient amount of carbon dioxide gas in the feed gas. Sufficient carbon dioxide gas can form enough fine nano-sized carbon dioxide bubbles during the buffer solution introduction stage.

[0044] The volume of carbon dioxide gas in the feed gas can be 5%, 6%, 7%, 8%, 9%, 10%, 15%, or 20% of the total volume of the feed gas.

[0045] In some alternative implementations, the mass m1 of the serpentine fragments and the volume V1 of the buffer solution satisfy the relationship: m1:V1=1:(1~80), where the unit of m1 is g and the unit of V1 is mL.

[0046] In some embodiments, the mass m1 of the serpentine fragments and the volume V1 of the buffer solution satisfy the relationship: m1:V1=1:(1~80). This ratio ensures that there are sufficient fine nano-carbon dioxide bubbles in the buffer solution, facilitating the full binding between the nano-carbon dioxide bubbles and the magnesium ions in the serpentine during the subsequent carbonization reaction stage, thereby improving the magnesium extraction rate from the serpentine.

[0047] When the mass m1 of the serpentine fragments is 1, the volume V1 of the buffer solution can be 1, 2, 3, 4, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 60, 70 or 80.

[0048] In some alternative embodiments, the carbonization reaction can be carried out by mechanical stirring. The stirring speed is 100 rpm to 600 rpm. The stirring time is 10 min to 180 min. The ball-to-material ratio for mechanical stirring is (10 to 35):1.

[0049] In some embodiments, the carbonization reaction can be carried out by mechanical stirring. The stirring speed can be 100 rpm to 600 rpm, the stirring time can be 10 min to 180 min, and the ball-to-material ratio can be (10 to 35):1. By reasonably setting these mechanical stirring parameters, the serpentine fragments can be fully crushed and their surface renewed during the mechanical stirring process, thereby achieving the purpose of activating the carbonization reaction. This allows nano-carbon dioxide bubbles to fully combine with magnesium ions on the serpentine surface and form stable magnesium bicarbonate complexes [Mg(HCO3)2]. These magnesium bicarbonate complexes can enter the leachate phase of the mixed suspension, thereby improving the extraction rate of magnesium ions from the serpentine.

[0050] The mechanical stirring speed can be 100 rpm, 250 rpm, 300 rpm, 350 rpm, 400 rpm, 450 rpm, 500 rpm, 550 rpm or 600 rpm.

[0051] The mechanical stirring time can be 10 min, 11 min, 12 min, 13 min, 14 min, 15 min, 16 min, 17 min, 18 min, 20 min, 30 min, 40 min, 50 min, 60 min, 70 min, 80 min, 90 min, 100 min, 110 min, 120 min, 130 min, 140 min, 150 min, 170 min, or 180 min.

[0052] The ball-to-material ratio for mechanical mixing can be 10:1, 15:1, 20:1, 25:1, 30:1, or 35:1.

[0053] It should be noted that mechanical stirring can be carried out using ball milling.

[0054] In some alternative embodiments, the average particle size of the serpentine crushed material is 13 μm to 48 μm.

[0055] In some embodiments, the average particle size of the serpentine fragments can be 13 μm to 48 μm. This particle size range provides the serpentine fragments with sufficient specific surface area. The serpentine fragments with sufficient specific surface area can adequately contact the nano-carbon dioxide bubbles, allowing magnesium ions on the serpentine surface to fully combine with the nano-carbon dioxide bubbles and form stable magnesium bicarbonate complexes. These magnesium bicarbonate complexes can enter the leachate phase of the mixed suspension, thereby improving the extraction rate of magnesium ions from the serpentine.

[0056] The average particle size of serpentine crushed material can be 13μm, 18μm, 23μm, 33μm or 48μm.

[0057] Figure 2 illustrates, exemplarily, a method for extracting magnesium from serpentine according to an embodiment of this disclosure.

[0058] In some alternative embodiments, as shown in Figure 2, the method for extracting magnesium from serpentine further includes, prior to passing a feed gas containing carbon dioxide gas into a buffer solution to obtain a buffer solution containing nano- and micro-carbon dioxide bubbles:

[0059] S101. Mix alkaline buffer particles with a hydrophilic solvent to obtain a buffer solution.

[0060] By mixing alkaline buffer particles with a hydrophilic solvent, the alkaline buffer particles dissolve in the hydrophilic solvent, thus forming a buffer solution with sufficient alkalinity. This sufficiently alkaline buffer solution allows nano-sized carbon dioxide bubbles to remain stably within the buffer solution, resulting in a large amount of buffer solution containing nano-sized carbon dioxide bubbles.

[0061] It should be noted that the hydrophilic solvent can be pure water.

[0062] In some alternative embodiments, the volume V2 of the hydrophilic solvent and the mass m2 of the alkaline buffer particles satisfy the relationship: V2:m2 = (8~100):1, where V2 is in mL and m2 is in g.

[0063] In some embodiments, the volume V2 of the hydrophilic solvent and the mass m2 of the alkaline buffer particles can satisfy the relationship: V2:m2 = (8~100):1. This ratio ensures that the buffer solution contains sufficient alkaline buffer particles. Sufficient alkaline buffer particles can form a buffer solution with sufficient alkalinity, which in turn promotes the stable presence of nano-carbon dioxide bubbles within the buffer solution, thus forming a large amount of buffer solution containing nano-carbon dioxide bubbles.

[0064] When the mass m2 of the alkaline buffer particles is 1, the volume V2 of the hydrophilic solvent can be 8, 9, 10, 15, 20, 30, 40, 50, 60, 70, 80, 90 or 100.

[0065] In some alternative embodiments, the alkaline buffer particles include at least one of the following: sodium hexametaphosphate, ammonium chloride, and ammonium bicarbonate.

[0066] In some embodiments, the alkaline buffer particles may include at least one of the following: sodium hexametaphosphate, ammonium chloride, and ammonium bicarbonate. This compositional characteristic of the alkaline buffer particles allows them to dissolve in a hydrophilic solvent, thereby forming a buffer solution with sufficient alkalinity. This sufficiently alkaline buffer solution promotes the stable presence of nano- and micro-carbon dioxide bubbles within the buffer solution, forming a buffer solution containing a large number of nano- and micro-carbon dioxide bubbles.

[0067] The present disclosure is further illustrated below with reference to specific embodiments. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to national / industry standards; if no corresponding national / industry standard exists, they are performed according to generally accepted international standards, conventional conditions, or conditions recommended by the manufacturer.

[0068] Example 1

[0069] As shown in Figure 2, a method for extracting magnesium from serpentine, which contains magnesium, includes:

[0070] S101. Mix alkaline buffer particles with a hydrophilic solvent to obtain a buffer solution;

[0071] S1. Pass the raw material gas containing carbon dioxide gas into the buffer solution to obtain a buffer solution containing nano-sized carbon dioxide bubbles, wherein the particle size of the nano-sized carbon dioxide bubbles is ≤100μm.

[0072] S2. Crush the serpentine to obtain serpentine fragments;

[0073] S3. The serpentine fragments and a buffer solution containing nano- and micro-carbon dioxide bubbles are subjected to a carbonation reaction to obtain a mixed suspension containing magnesium bicarbonate leachate; and

[0074] S4. The mixed suspension containing magnesium bicarbonate leachate is subjected to solid-liquid separation to obtain a magnesium-containing liquid phase.

[0075] The chemical composition of serpentine is shown in Table 1.

[0076] Table 1. Distribution of chemical composition of serpentine

[0077]

[0078] Nanoscale carbon dioxide bubbles include fine-particle carbon dioxide bubbles. The volume of fine-particle carbon dioxide bubbles accounts for 70% of the total volume of nanoscale carbon dioxide bubbles. The particle size of fine-particle carbon dioxide bubbles is ≤1μm.

[0079] The particle size of nano-carbon dioxide bubbles ranges from 0.1 μm to 100 μm.

[0080] The volume of carbon dioxide gas in the feed gas is greater than or equal to 15% of the total volume of the feed gas.

[0081] The mass m1 of the serpentine fragments and the volume V1 of the buffer solution satisfy the relationship: m1:V1=1:5. If the unit of m1 is g, then the unit of V1 is mL.

[0082] The carbonization reaction was carried out by mechanical stirring at a speed of 300 rpm for 60 minutes. The ball-to-material ratio for mechanical stirring was 25:1.

[0083] The average particle size of the serpentine crushed material is 18 μm.

[0084] The volume V2 of the hydrophilic solvent and the mass m2 of the alkaline buffer particles satisfy the relationship: V2:m2 = 10:1. If the unit of V2 is mL, then the unit of m2 is g. In this case, the mass of the alkaline buffer particles accounts for 10% of the mass of the buffer solution.

[0085] The alkaline buffer particles are ammonium bicarbonate.

[0086] Example 2

[0087] Based on the content disclosed in Example 1, the following changes were made to the reaction conditions:

[0088] The mass m1 of the serpentine fragments and the volume V1 of the buffer solution satisfy the relationship: m1:V1=1:1. If the unit of m1 is g, then the unit of V1 is mL.

[0089] The carbonization reaction is carried out by mechanical stirring at a speed of 500 rpm for 120 min, with a ball-to-material ratio of 10:1.

[0090] The average particle size of the serpentine crushed material is 23 μm.

[0091] Example 3

[0092] Based on the content disclosed in Example 1, the following changes were made to the reaction conditions:

[0093] The mass m1 of the serpentine fragments and the volume V1 of the buffer solution satisfy the relationship: m1:V1=1:80. If the unit of m1 is g, then the unit of V1 is mL.

[0094] The carbonization reaction is carried out by mechanical stirring at a speed of 600 rpm for 10 minutes, with a ball-to-material ratio of 35:1.

[0095] The average particle size of the serpentine crushed material is 35 μm.

[0096] Example 4

[0097] Based on the content disclosed in Example 1, the following changes were made to the reaction conditions:

[0098] The volume V2 of the hydrophilic solvent and the mass m2 of the alkaline buffer particles satisfy the relationship: V2:m2 = 100:1. If the unit of V2 is mL, then the unit of m2 is g. In this case, the mass of the alkaline buffer particles accounts for 1% of the mass of the buffer solution.

[0099] The alkaline buffer particles are sodium hexametaphosphate.

[0100] Example 5

[0101] Based on the content disclosed in Example 1, the following changes were made to the reaction conditions:

[0102] Nanoscale carbon dioxide bubbles include fine-particle carbon dioxide bubbles, and the volume of fine-particle carbon dioxide bubbles accounts for 50% of the total volume of nanoscale carbon dioxide bubbles.

[0103] Comparative Example 1

[0104] Based on the content disclosed in Example 1, the following changes were made to the reaction conditions:

[0105] The carbonization reaction is carried out using only mechanical stirring, without adding nano-sized carbon dioxide bubbles.

[0106] Comparative Example 2

[0107] Based on the content disclosed in Example 1, the following changes were made to the reaction conditions:

[0108] Only a buffer solution containing nano- and micro-carbon dioxide bubbles is used, and the buffer solution is stirred normally, without mechanical stirring by ball milling.

[0109] Comparative Example 3

[0110] Based on the content disclosed in Example 1, the following changes were made to the reaction conditions:

[0111] Only a buffer solution containing conventional carbon dioxide bubbles (non-nano-micro level and well-dispersed bubbles) is used.

[0112] Comparative Example 4

[0113] Based on the content disclosed in Example 1, the following changes were made to the reaction conditions:

[0114] No alkaline buffer particles are added to the buffer solution.

[0115] Comparative Example 5

[0116] Based on the content disclosed in Example 1, the following changes were made to the reaction conditions:

[0117] The volume of fine-particle carbon dioxide bubbles is 40% of the total volume of nano- and micro-sized carbon dioxide bubbles.

[0118] Comparative Example 6

[0119] Based on the content disclosed in Example 1, the following changes were made to the reaction conditions:

[0120] The mechanical stirring speed was 50 rpm, and the mechanical stirring time was 200 min.

[0121] Comparative Example 7

[0122] Based on the content disclosed in Example 1, the following changes were made to the reaction conditions:

[0123] The mechanical stirring speed was 1000 rpm, and the mechanical stirring time was 5 minutes.

[0124] The relevant experimental data and results are as follows.

[0125] The magnesium extraction rates of serpentine in each embodiment and comparative example were statistically analyzed, and the results are shown in Table 2.

[0126] Table 2. Comparison of magnesium extraction rates from serpentine in each example and comparative example.

[0127]

[0128] As shown in Table 2, this disclosure provides a method for extracting magnesium from serpentine. This method utilizes the unique physicochemical properties of nano-carbon dioxide bubbles. By thoroughly mixing nano-carbon dioxide bubbles with serpentine fragments, and leveraging the synergistic effect of the carbonization reaction activation described above and the nano-carbon dioxide bubbles, the phase structure of serpentine can be effectively broken down. This promotes the carbonization reaction between magnesium in the serpentine and the nano-carbon dioxide bubbles, forming a magnesium bicarbonate complex. The formed magnesium bicarbonate complex enters the leaching liquid phase of the mixed suspension, thereby significantly increasing the magnesium leaching rate from serpentine to over 92%.

[0129] Furthermore, the methods described in Comparative Example 1 (using only mechanical stirring without introducing a buffer solution containing nano- or micro-carbon dioxide bubbles), Comparative Example 2 (introducing only a buffer solution containing nano- or micro-carbon dioxide bubbles without mechanical stirring), and Comparative Example 5 (introducing a buffer solution containing small-volume nano- or micro-carbon dioxide bubbles with fine-particle size), all resulted in low magnesium extraction rates from serpentine. This indicates that the carbonization reaction achieved through mechanical stirring, combined with a suitable volume of nano- or micro-carbon dioxide bubbles, is necessary to effectively disrupt the phase structure of serpentine.

[0130] Furthermore, according to Comparative Example 3, the method of simply introducing a buffer solution containing conventional carbon dioxide bubbles resulted in a low concentration of conventional carbon dioxide bubbles in the buffer solution due to their low solubility. This insufficient concentration prevented them from effectively participating in the carbonization reaction, leading to a low magnesium extraction rate from serpentine. This indicates that carbon dioxide needs to exist in the buffer solution in a nano-microstructure form to fully react during the carbonization process. Additionally, according to Comparative Example 4, using only an aqueous solution as the buffer resulted in a slightly acidic final buffer solution. This reduced the solubility of nano-carbon dioxide bubbles in the buffer solution, resulting in a low concentration of nano-carbon dioxide bubbles in the resulting buffer solution, further contributing to a low magnesium extraction rate from serpentine.

[0131] Furthermore, according to Comparative Example 6, using a lower stirring speed and a longer stirring time, and according to Comparative Example 7, using a higher stirring speed and a shorter stirring time, also resulted in a lower magnesium extraction rate from serpentine. This indicates that the appropriate stirring speed and time have a certain impact on the degree of carbonization reaction.

[0132] In summary, this disclosure provides a method for extracting magnesium from serpentine. This method involves thoroughly mixing nano-carbon dioxide bubbles with serpentine fragments. Through the synergistic effect of carbonization activation and nano-carbon dioxide bubbles, the phase structure of serpentine can be effectively broken down, thereby significantly increasing the magnesium leaching rate from serpentine to over 92%.

[0133] Furthermore, this disclosure provides a method for extracting magnesium from serpentine. After the carbonization reaction, this method can separate the magnesium-containing liquid phase and the tailings simply through solid-liquid separation, effectively avoiding the generation of waste acid and alkali solutions during traditional serpentine extraction. In addition, this method does not generate any harmful dust or waste gas throughout the entire process, making it an environmentally friendly process. Moreover, this method has the advantages of a short process flow, low cost, and good magnesium extraction effect. It can also achieve the harmless treatment of serpentine, which is of great significance for the efficient and clean extraction of magnesium from serpentine.

[0134] The technical solutions provided in this disclosure have the following advantages compared with the prior art:

[0135] This disclosure provides a method for extracting magnesium from serpentine. The method involves passing a raw material gas containing carbon dioxide into a buffer solution to form a buffer solution containing nano-sized carbon dioxide bubbles. These nano-sized carbon dioxide bubbles have a particle size of less than 100 μm and can dissolve in large quantities in the buffer solution. Furthermore, due to the high pressure inside the nano-sized carbon dioxide bubbles, during the subsequent carbonization reaction stage, the collapse of these high-pressure bubbles releases a large amount of energy and generates a local cavitation effect within the buffer solution containing the nano-sized carbon dioxide bubbles. Based on this local cavitation effect, the buffer solution containing the nano-sized carbon dioxide bubbles can exert a shearing effect on the serpentine fragments, thereby disrupting the phase structure of the serpentine and increasing the dissolution rate of magnesium ions from the serpentine. In addition, these nano-sized carbon dioxide bubbles have strong negative charge, making it easier for them to combine with magnesium ions in the serpentine fragments and promote a direct reaction between the nano-sized carbon dioxide bubbles and magnesium ions, thereby increasing the degree of carbonization reaction and ultimately improving the extraction rate of magnesium from the serpentine.

[0136] Furthermore, the method for extracting magnesium from serpentine provided in this disclosure has the following advantages:

[0137] 1. Process simplification and product purity optimization

[0138] (1) Process integration

[0139] Traditional processes for extracting magnesium from serpentine require complex separation steps such as multi-stage neutralization and ion exchange. However, the method disclosed in this paper achieves integrated leaching and carbonization by simultaneously conducting physical disruption and chemical reactions using nano-micro carbon dioxide bubbles. Furthermore, based on the electrostatic adsorption of nano-micro carbon dioxide bubbles and the inhibition of silicon by the alkaline environment, in-situ selective adsorption and separation of magnesium ions are achieved, reducing the number of steps in the magnesium extraction process from serpentine by more than 50%.

[0140] (2) Purity control

[0141] The method disclosed herein can directly generate magnesium bicarbonate Mg(HCO3)2 during the carbonization reaction stage and can suppress the silica gel encapsulation phenomenon in serpentine, ultimately enabling the purity of serpentine in magnesium ion leaching solution to reach over 99.5%, which is superior to the acid leaching method with a magnesium ion leaching solution purity of 85%~88%.

[0142] 2. Technical advantages, as shown in Table 3.

[0143] Table 3 Distribution of Technical Indicator Advantages

[0144]

[0145] 3. Residue resource utilization potential

[0146] Traditional acid leaching methods require separate treatment of the iron and silicon components in the residue after magnesium extraction from serpentine (e.g., alkali fusion and oxidation are needed to extract Fe2O3). However, the method disclosed in this paper allows for the direct addition of 5% Na2CO3 to the siliceous residue after magnesium extraction for roasting to prepare sodium silicate (Na2SiO3), since the residue is not corroded by strong acid. Alternatively, the iron concentrate and silica powder can be directly separated by magnetic separation, thereby enabling the high-value utilization of all components in serpentine.

[0147] Therefore, the method disclosed herein, through the aforementioned technological innovations, is significantly superior to traditional processes in terms of environmental friendliness, reaction efficiency, and product quality, and is in line with the development trend of green metallurgical technology.

[0148] The above description is merely a specific embodiment of this disclosure, enabling those skilled in the art to understand or implement it. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined in this disclosure may be implemented in other embodiments without departing from the spirit or scope of this disclosure. Therefore, this disclosure is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed in this disclosure.

Claims

1. A method for extracting magnesium from serpentine, wherein the serpentine contains magnesium, the method comprising: A raw material gas containing carbon dioxide gas is passed into a buffer solution to obtain a buffer solution containing nano- and micro carbon dioxide bubbles, wherein the particle size of the nano- and micro carbon dioxide bubbles is ≤100μm. The serpentine is crushed to obtain serpentine fragments; The serpentine fragments and the buffer solution containing nano- and micro-carbon dioxide bubbles are subjected to a carbonization reaction to obtain a mixed suspension containing magnesium bicarbonate leachate; and, The mixed suspension containing magnesium bicarbonate leachate is subjected to solid-liquid separation to obtain a magnesium-containing liquid phase.

2. The method according to claim 1, wherein, The nano-carbon dioxide bubbles include fine-particle carbon dioxide bubbles, the volume of which is less than or equal to 50% of the total volume of the nano-carbon dioxide bubbles, and the particle size of which is ≤1μm.

3. The method according to claim 1, wherein, The particle size of the nano-carbon dioxide bubbles is 0.1 μm to 100 μm.

4. The method according to claim 1, wherein, The volume of carbon dioxide gas in the raw material gas is greater than or equal to 5% of the total volume of the raw material gas.

5. The method according to claim 1, wherein, The mass m1 of the serpentine fragments and the volume V1 of the buffer solution satisfy the following relationship: m1:V1=1:(1~80). If the unit of m1 is g, then the unit of V1 is mL.

6. The method according to claim 1, wherein, The carbonization reaction is carried out by mechanical stirring, the stirring speed is 100 rpm to 600 rpm, and the stirring time is 10 min to 180 min.

7. The method according to claim 1, wherein the average particle size of the serpentine crushed material is 13μm~48μm.

8. The method according to claim 1, wherein, Before passing the raw material gas containing carbon dioxide gas into the buffer solution to obtain a buffer solution containing nano- and micro-carbon dioxide bubbles, the method further includes: The buffer solution is obtained by mixing alkaline buffer particles with a hydrophilic solvent.

9. The method according to claim 8, wherein, The volume V2 of the hydrophilic solvent and the mass m2 of the alkaline buffer particles satisfy the following relationship: V2:m2 = (8~100):

1. If the unit of V2 is mL, then the unit of m2 is g.

10. The method according to claim 8, wherein, The alkaline buffer particles include at least one of the following: sodium hexametaphosphate, ammonium chloride, and ammonium bicarbonate.

11. The method according to any one of claims 1 to 10, wherein, The carbonization reaction includes mechanical stirring by ball milling, wherein the ball-to-material ratio of the mechanical stirring is (10~35):1.

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