Method for separating calcium and magnesium components of calcined dolomite based on carbon dioxide

Abstract

The invention relates to the technical field of mineral processing, in particular to a method for separating calcium and magnesium components of calcined dolomite based on carbon dioxide. The calcined dolomite comprises magnesium oxide and calcium oxide, and the method comprises the following steps: digesting the calcined dolomite and water to obtain a calcined dolomite suspension; carrying out bubbling treatment on the raw material gas containing carbon dioxide under a preset condition to obtain fine raw material bubbles; carrying out carbonization reaction on the fine raw material bubbles and the calcined dolomite turbid liquid to obtain a mixed turbid liquid; and carrying out solid-liquid separation on the mixed turbid liquid to respectively obtain calcium carbonate and a magnesium-containing liquid phase. According to the method, raw material gas containing carbon dioxide is subjected to bubbling treatment to obtain fine raw material bubbles, then the fine raw material bubbles and calcined dolomite turbid liquid are promoted to be subjected to gas-liquid-solid three-phase carbonization reaction, and the separation effect of calcium and magnesium components of the calcined dolomite turbid liquid can be improved under the harmless condition; the grades of the final calcium carbonate and magnesium oxide are respectively over 98 percent.

Description

Technical Field

[0001] The present application relates to the technical field of mineral processing, and in particular to a method for separating calcium and magnesium components of calcined dolomite based on carbon dioxide. Background Art

[0002] Carbonization is one of the main methods for separating the calcium and magnesium components of calcined dolomite. The carbonization method refers to first calcining dolomite at high temperature to obtain magnesium oxide and calcium oxide, and then digesting and pulping the magnesium oxide and calcium oxide to obtain a calcined dolomite suspension containing magnesium hydroxide and calcium hydroxide. In a carbonization tower, carbon dioxide gas is introduced into the calcined dolomite suspension after digestion and pulping to carbonize magnesium oxide and calcium oxide. After the calcium hydroxide in the calcined dolomite suspension is converted into calcium carbonate, carbon dioxide is continued to be introduced to promote the conversion of magnesium hydroxide in the mixed slurry into soluble salt magnesium bicarbonate. Therefore, the carbonization method of calcined dolomite has the characteristics of simple process, but the purity of the calcium carbonate product obtained by the carbonization method is not high, which makes it difficult to effectively separate the calcium and magnesium components of calcined dolomite by the carbonization method.

[0003] Based on the problems existing in the carbonization method for calcined dolomite, various carbonization improvement processes have gradually become a technical development trend. For example, additives are introduced into the above carbonization process to improve the separation effect of the calcium and magnesium components of calcined dolomite, but the additives will be converted into other wastes, making it difficult to achieve harmless treatment of the carbonization method for calcined dolomite.

[0004] Existing improved carbonization processes include: (1) an improved carbonization method for separating calcium and magnesium to produce high-purity basic magnesium carbonate. This method uses oxalate as an additive to adjust the acidity and perform secondary carbonization on the carbonized mixed slurry, so that the calcium in the mixed slurry is precipitated from the mixed slurry in the form of a mixture of calcium oxalate and calcium carbonate, while the magnesium remains in the liquid phase in the form of soluble magnesium bicarbonate; (2) a method for separating calcium and magnesium. This method uses acetylacetone as an additive to promote the magnesium hydroxide of calcined dolomite to enter the liquid phase in the form of a magnesium complex through the complexation reaction of acetylacetone, while the calcium hydroxide is still separated from the liquid phase in the form of calcium carbonate, thereby achieving the separation of calcium and magnesium in calcined dolomite; (3) a calcium and magnesium separation method based on the carbonization stage. The method uses an alcoholamine compound as an additive, and the calcium and magnesium in the mixed slurry are respectively complexed through the complexation reaction of the alcoholamine compound, so that the carbonization of the calcium and magnesium in the mixed slurry needs to be carried out step by step strictly according to the distribution of the pH range of the mixed slurry. Therefore, by adjusting the pH range of the mixed slurry, high-purity calcium carbonate and refined heavy magnesium water can be directly prepared. Summary of the invention

[0005] The present application provides a method for separating calcium and magnesium components of calcined dolomite based on carbon dioxide to solve the following technical problem: how to improve the separation effect of calcium and magnesium components of calcined dolomite suspension under harmless treatment.

[0006] In a first aspect, the present application provides a method for separating calcium and magnesium components of calcined dolomite based on carbon dioxide, wherein the calcined dolomite comprises calcium oxide and magnesium oxide, and the method comprises:

[0007] Digesting calcined dolomite and water to obtain a calcined dolomite suspension;

[0008] The raw gas containing carbon dioxide is subjected to bubbling treatment under preset conditions to obtain fine raw gas bubbles; wherein the average size of the fine raw gas bubbles is ≤100 μm;

[0009] Carrying out a carbonization reaction between the fine raw material bubbles and the calcined dolomite suspension to generate magnesium bicarbonate and calcium carbonate to obtain a mixed suspension; and

[0010] The mixed suspension is subjected to solid-liquid separation to obtain calcium carbonate and a magnesium-containing liquid phase respectively.

[0011] Optionally, the average size of the fine raw material bubbles is 0.1 μm to 100 μm.

[0012] Optionally, the flow rate of the fine raw material bubbles is 0.1 L / min to 1.5 L / min.

[0013] Optionally, the bubbling treatment time is ≥12 min.

[0014] Optionally, the weight of carbon dioxide in the raw gas is ≥ 5% of the total weight of the raw gas.

[0015] Optionally, the temperature of the carbonization reaction is 0°C to 50°C, and the time of the carbonization reaction is 10 min to 240 min.

[0016] Optionally, the process of subjecting the raw gas containing carbon dioxide to bubbling treatment under preset conditions to obtain fine raw gas bubbles comprises the following steps:

[0017] The raw material gas containing carbon dioxide is stirred and mixed and ultrasonically dispersed synchronously at a preset stirring speed and a preset ultrasonic frequency, so that the carbon dioxide forms bubbles to obtain fine raw material bubbles.

[0018] Optionally, the preset stirring speed is ≥50r / min; and / or

[0019] The preset ultrasonic frequency is ≥20 Hz.

[0020] Optionally, the ultrasonic dispersion includes a plurality of ultrasonic working segments and a plurality of ultrasonic interval segments, and the time t1 of the ultrasonic working segment and the time t2 of the ultrasonic interval segment satisfy the relationship: t1:t2=1:(3-10).

[0021] Optionally, the duration of the ultrasonic working section is 1 min to 10 min, and the duration of the ultrasonic interval section is 10 min to 30 min.

[0022] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0023] The embodiment of the present application provides a method for separating calcium and magnesium components of calcined dolomite based on carbon dioxide. The method first performs a bubbling treatment on a raw gas containing carbon dioxide, so that the raw gas is converted into fine raw gas bubbles with an average size of ≤100μm. The fine raw gas bubbles of sufficiently small size can stably move in the calcined dolomite suspension, reducing the possibility of fusion and rupture of two adjacent raw gas bubbles and gas escape during the rising process of traditional large-sized raw gas bubbles, and can prolong the existence time of the fine raw gas bubbles in the calcined dolomite suspension. The fine raw gas bubbles that exist for a long time can spontaneously shrink and rupture in the calcined dolomite suspension. The shrinkage and rupture process will Huge energy is released to prompt carbon dioxide gas to quickly enter the calcined dolomite suspension and form carbonate ions. These carbonate ions will undergo a crystallization reaction with the magnesium hydroxide and calcium hydroxide in the calcined dolomite suspension, so that a large amount of calcium carbonate and magnesium-containing liquid phase can be obtained under harmless conditions; in addition, the fine raw material bubbles that exist for a long time can be evenly distributed in the calcined dolomite suspension and attached to the surface of the calcium hydroxide, and provide a large number of nucleation sites on the surface of the calcium hydroxide to facilitate the formation of the calcium carbonate phase, prompting the calcium hydroxide in the dolomite mixed slurry to separate from the liquid phase in the form of calcium carbonate, thereby improving the separation effect of the calcium and magnesium components of the calcined dolomite suspension. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0026] Figure 1 A schematic flow chart of a method for separating calcium and magnesium components of calcined dolomite based on carbon dioxide provided in an embodiment of the present application;

[0027] Figure 2 A detailed schematic diagram of a method for separating calcium and magnesium components of calcined dolomite based on carbon dioxide provided in an embodiment of the present application;

[0028] Figure 3 Schematic diagram of the carbonization reactor used for the bubbling treatment provided in the embodiments of the present application. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0030] Various embodiments of the present application may be presented in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity and should not be understood as a rigid limitation on the scope of the present application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within the 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., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, which applies regardless of the range; in addition, whenever a numerical range is indicated in this document, it is meant to include any cited numbers (fractions or integers) within the indicated range.

[0031] In this document, the terms including "including" and "including" mean "including but not limited to". Relational terms such as "first" and "second" are only used 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 association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone; where A and B can be singular or plural. "At least one" means one or more, and "plurality" 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 all 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" such as parts by weight and parts by mass indicate the proportional relationship between the components. In the proportional relationship involved in this article, the parameters that need to be described by proportion should be understood as the first term of the proportional formula in the order of description, and the proportional numbers should be understood as the second term of the proportional formula. For example, if the mass ratio of substance A, substance B and substance C is 1:2:3, then substance A, substance B and substance C should correspond to the proportional numbers in the proportional formula 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.

[0032] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in this article can be purchased from the market or prepared by existing methods.

[0033] It should be noted that, with respect to the prior art (1) recorded in the background technology, the inventors found that: this method has the disadvantages of complex process and high equipment investment, and a large amount of mixed precipitate containing calcium oxalate and magnesium oxalate will be produced during the secondary carbonization, and there are problems such as inefficient use of calcium. With respect to the prior art (2) recorded in the background technology, the inventors found that: this method introduces an organic phase, and subsequent steps such as organic phase separation and wastewater treatment need to be added, which prolongs the preparation process. With respect to the prior art (3) recorded in the background technology, the inventors found that: this method introduces organic additives, which makes the cost of the method higher, and the pH control of the mixed slurry is relatively fine, which makes the requirements for the actual control operation more stringent, and it is difficult to achieve harmless separation of the mixed slurry.

[0034] Therefore, how to improve the separation effect of calcium and magnesium components of calcined dolomite suspension under harmless treatment is a technical problem that urgently needs to be solved.

[0035] Figure 1 A schematic flow chart of a method for separating calcium and magnesium components of calcined dolomite based on carbon dioxide is shown as an example;

[0036] like Figure 1 As shown, the embodiment of the present application provides a method for separating calcium and magnesium components of calcined dolomite based on carbon dioxide, wherein the calcined dolomite includes magnesium oxide and calcium oxide, and the method includes:

[0037] S1. The calcined dolomite and water are digested to obtain a calcined dolomite suspension;

[0038] S2. The raw gas containing carbon dioxide is bubbled under preset conditions to obtain fine raw material bubbles; wherein the average size of the fine raw material bubbles is ≤100 μm;

[0039] S3. The fine raw material bubbles and the calcined dolomite suspension are subjected to a carbonization reaction to generate magnesium bicarbonate and calcium carbonate to obtain a mixed suspension; and

[0040] S4. performing solid-liquid separation on the mixed suspension to obtain calcium carbonate and a magnesium-containing liquid phase respectively.

[0041] It should be noted that the weight m1 of the calcined dolomite and the weight m2 of water satisfy the relationship: m1:m2=1:15, the digestion temperature may be 50°C, and the digestion time may be 3 hours.

[0042] It should be noted that the calcined dolomite is obtained by calcining dolomite raw materials, the dolomite raw materials include fine-grained materials, the weight of the fine-grained materials m3 and the weight of the dolomite raw materials m4 can satisfy the relationship: m3:m4=80:100, and the particle size of the fine-grained materials is ≤75μm. The calcination temperature can be 1000°C, and the calcination time can be 6h.

[0043] It should be noted that the bubbling treatment can be carried out by a combination of stirring and mixing and ultrasonic dispersion. The stirring and mixing can be carried out by a common mechanical stirring device, and the ultrasonic dispersion can be achieved by an existing ultrasonic combination device. The specific ultrasonic combination device can be formed by combining a self-excited ultrasonic generator and a separately excited ultrasonic generator.

[0044] It should be noted that the raw gas can be pure carbon dioxide, a mixed gas of carbon dioxide and air, or a mixed gas of carbon dioxide and flue gas containing carbon dioxide.

[0045] It should be noted that the calcined dolomite suspension is a suspension containing calcium hydroxide and magnesium hydroxide.

[0046] Figure 3A schematic diagram of a carbonization reactor used for bubbling treatment provided in an embodiment of the present application is exemplarily shown;

[0047] It should be noted that the bubbling treatment can be performed in Figure 3 The carbonization reactor shown in the figure is carried out. The specific carbonization reactor can refer to the device structure of the intermittent stirring carbonization tower; the intermittent stirring carbonization tower is modified by adding a stirrer based on the structural basis of the bubbling carbonization tower. The microbubbles in the intermittent stirring carbonization tower are generated by sucking in the gas through the negative pressure effect generated by the venturi jet or the impeller of the stirrer, and further breaking it into microbubbles or squeezing the aeration head to form microbubbles.

[0048] It should be noted that the pressure of the bubble treatment can be 101 kPa.

[0049] It should be noted that the magnesium-containing liquid phase can first be subjected to pyrolysis, filtration and drying treatments in sequence to obtain basic magnesium carbonate, and then the basic magnesium carbonate is calcined to obtain magnesium oxide; the calcination temperature can be 650° C., and the calcination time can be 2 hours.

[0050] In some optional embodiments, the average size of the fine raw material bubbles is 0.1 μm to 100 μm;

[0051] In these embodiments, the average size of the fine raw material bubbles can be 0.1 μm to 100 μm, which promotes the fine raw material bubbles to have a sufficiently small size. The fine raw material bubbles of a sufficiently small size can stably move in the calcined dolomite suspension to extend the existence time of the fine raw material bubbles in the calcined dolomite suspension. The fine raw material bubbles that exist for a long time can, on the one hand, spontaneously shrink and rupture in the calcined dolomite suspension, and can be processed in a harmless manner to obtain a large amount of calcium carbonate and magnesium-containing liquid phase; on the other hand, they can be evenly distributed in the calcined dolomite suspension and adhere to the surface of calcium hydroxide, promoting the calcium hydroxide in the dolomite mixed slurry to separate from the liquid phase in the form of calcium carbonate, thereby improving the separation effect of the calcium and magnesium components of the calcined dolomite suspension.

[0052] The average size of the fine raw material bubbles can be 0.1μm, 0.22μm, 0.5μm, 1μm, 2μm, 5μm, 10μm, 20μm, 30μm, 40μm, 50μm, 60μm, 70μm, 80μm, 90μm or 100μm.

[0053] It should be noted that, when the average size of the fine raw material bubbles is greater than 100 μm, the gas volume of the fine raw material bubbles is too large, which will increase the buoyancy of the fine raw material bubbles, reduce the residence time of the fine raw material bubbles in the calcined dolomite suspension, and also cause the fine raw material bubbles to overflow the calcined dolomite suspension, affecting the mass transfer effect of the fine raw material bubbles in the calcined dolomite suspension; in addition, the movement of large-sized fine raw material bubbles in the calcined dolomite suspension is easily hindered by the movement of smaller-sized fine raw material bubbles, and it is difficult for them to shrink and rupture spontaneously, thereby affecting the separation effect of the calcium and magnesium components of the calcined dolomite suspension.

[0054] In some optional embodiments, the flow rate of the fine raw material bubbles is 0.1 L / min to 1.5 L / min;

[0055] In these embodiments, the flow rate of the fine raw material bubbles can be 0.1L / min to 1.5L / min, which promotes the stable movement of the fine raw material bubbles in the calcined dolomite suspension to extend the existence time of the fine raw material bubbles in the calcined dolomite suspension. The fine raw material bubbles that exist for a long time can, on the one hand, spontaneously shrink and rupture in the calcined dolomite suspension, and can be processed in a harmless manner to obtain a large amount of calcium carbonate and magnesium-containing liquid phase; on the other hand, they can be evenly distributed in the calcined dolomite suspension and adhere to the surface of calcium hydroxide, promoting the calcium hydroxide in the dolomite mixed slurry to separate from the liquid phase in the form of calcium carbonate, thereby improving the separation effect of the calcium and magnesium components of the calcined dolomite suspension.

[0056] The flow rate of the fine raw material bubbles can be 0.1 L / min, 0.2 L / min, 0.5 L / min, 0.6 L / min, 0.7 L / min, 0.9 L / min, 1.0 L / min, 1.3 L / min or 1.5 L / min.

[0057] In some optional embodiments, the bubbling treatment time is ≥ 12 min;

[0058] In these embodiments, the bubbling treatment time is ≥ 12 min, so that the raw gas containing carbon dioxide has enough time to be transformed into fine raw gas bubbles.

[0059] In some optional embodiments, the weight of carbon dioxide in the feed gas is ≥ 5% of the total weight of the feed gas;

[0060] In these embodiments, the carbon dioxide in the raw gas can be ≥ 5% of the total weight of the raw gas, so that the raw gas has sufficient carbon dioxide. The sufficient amount of carbon dioxide can be subjected to a bubbling treatment to obtain fine raw gas bubbles of a small enough size. The fine raw gas bubbles of a small enough size can stably move in the calcined dolomite suspension to extend the existence time of the fine raw gas bubbles in the calcined dolomite suspension. The fine raw gas bubbles that exist for a long time can, on the one hand, spontaneously shrink and rupture in the calcined dolomite suspension, and can be processed in a harmless manner to obtain a large amount of calcium carbonate and magnesium-containing liquid phase; on the other hand, they can be evenly distributed in the calcined dolomite suspension and adhere to the surface of calcium hydroxide, so that the calcium hydroxide in the dolomite mixed slurry is separated from the liquid phase in the form of calcium carbonate, thereby improving the separation effect of the calcium and magnesium components of the calcined dolomite suspension.

[0061] In some optional embodiments, the temperature of the carbonization reaction is 0°C to 50°C, and the time of the carbonization reaction is 10min to 240min;

[0062] In these embodiments, the temperature of the carbonization reaction can be 0°C to 50°C, and the time of the carbonization reaction can be 10min to 240min, which promotes the long-term existence of fine raw material bubbles in the calcined dolomite suspension. On the one hand, the fine raw material bubbles that exist for a long time can spontaneously shrink and rupture in the calcined dolomite suspension, and can be processed in a harmless manner to obtain a large amount of calcium carbonate and magnesium-containing liquid phase; on the other hand, they can be evenly distributed in the calcined dolomite suspension and adhere to the surface of calcium hydroxide, promoting the calcium hydroxide in the dolomite mixed slurry to separate from the liquid phase in the form of calcium carbonate, thereby improving the separation effect of the calcium and magnesium components of the calcined dolomite suspension.

[0063] The temperature of the carbonization reaction may be 0°C, 10°C, 20°C, 30°C, 40°C or 50°C.

[0064] The carbonization reaction time can be 10min, 20min, 30min, 40min, 50min, 60min, 70min, 80min, 90min,

[0065] Figure 2 A detailed flow chart of a method for separating calcium and magnesium components of calcined dolomite based on carbon dioxide provided in an embodiment of the present application is exemplarily shown;

[0066] In some optional embodiments, such as Figure 2 As shown, the process of bubbling the raw gas containing carbon dioxide under preset conditions to obtain fine raw gas bubbles includes the following steps:

[0067] S201. The raw gas containing carbon dioxide is stirred and mixed and ultrasonically dispersed synchronously at a preset stirring speed and a preset ultrasonic frequency, so that the carbon dioxide forms bubbles to obtain fine raw gas bubbles;

[0068] In these embodiments, stirring mixing at a preset stirring speed and ultrasonic dispersion at a preset ultrasonic frequency are used to promote the sufficient conversion of the carbon dioxide-containing raw gas into a large number of fine raw gas bubbles, and the average size of the fine raw gas bubbles is made ≤100 μm, and the sufficiently small fine raw gas bubbles can stably move in the calcined dolomite suspension to extend the existence time of the fine raw gas bubbles in the calcined dolomite suspension, and the separation effect of the calcium and magnesium components of the calcined dolomite suspension can be improved under harmless treatment.

[0069] In some optional embodiments, the preset stirring speed is ≥50 r / min; and / or

[0070] The preset ultrasonic frequency is ≥20 Hz;

[0071] In these embodiments, the preset stirring speed is ≥50r / min, and the preset ultrasonic frequency is ≥20Hz, so that the raw gas containing carbon dioxide is fully converted into a large number of fine raw bubbles, and the average size of the fine raw bubbles is ≤100μm, and the sufficiently small fine raw bubbles can move stably in the calcined dolomite suspension to extend the existence time of the fine raw bubbles in the calcined dolomite suspension.

[0072] It should be noted that, according to the working equipment limitation of the carbonization reactor, the maximum speed of the preset stirring speed may be 400 r / min, and the maximum frequency of the preset ultrasonic frequency may be 40 Hz.

[0073] In some optional embodiments, the ultrasonic dispersion includes a plurality of ultrasonic working segments and a plurality of ultrasonic interval segments, and the time t1 of the ultrasonic working segment and the time t2 of the ultrasonic interval segment satisfy the relationship: t1:t2=1:(3-10);

[0074] In these embodiments, the ultrasonic dispersion includes multiple ultrasonic working sections and ultrasonic interval sections, and the time t1 of the ultrasonic working section and the time t2 of the ultrasonic interval section satisfy the relationship: t1:t2=1:(3~10), which can promote the ultrasonic dispersion to be carried out in a segmented form, so as to facilitate the conversion of the carbon dioxide-containing raw gas in different time periods into fine raw material bubbles with an average size of ≤100μm, and the fine raw material bubbles small enough can move stably in the calcined dolomite suspension to extend the existence time of the fine raw material bubbles in the calcined dolomite suspension.

[0075] The time t1 of the ultrasonic working section and the time t2 of the ultrasonic interval section may satisfy the relationship: t1:t2=1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9 or 1:10.

[0076] In some optional embodiments, the duration of the ultrasonic working section is 1 min to 10 min, and the duration of the ultrasonic interval section is 10 min to 30 min;

[0077] In these embodiments, the duration of the ultrasonic working section can be 1 min to 10 min, and the duration of the ultrasonic interval section can be 10 min to 30 min, which promotes the uniform separation of the ultrasonic working section and the ultrasonic interval section, and promotes the conversion of the raw gas containing carbon dioxide into fine raw bubbles with an average size of ≤100 μm, and the fine raw bubbles small enough can stably move in the calcined dolomite suspension, so as to extend the existence time of the fine raw bubbles in the calcined dolomite suspension.

[0078] The duration of the ultrasonic working section can be 1 min, 2 min, 3 min, 4 min, 5 min, 6 min, 7 min, 8 min, 9 min or 10 min.

[0079] The duration of the ultrasound interval can be 10 min, 15 min, 20 min, 25 min or 30 min.

[0080] The present application is further described below in conjunction with specific examples. The experimental methods in the following examples where specific conditions are not specified are usually measured in accordance with national standards / industry standards; if there are no corresponding national standards / industry standards, they are measured in accordance with common international standards, conventional conditions or conditions recommended by the manufacturer.

[0081] Example 1

[0082] like Figure 2 As shown, a method for separating calcium and magnesium components of calcined dolomite based on carbon dioxide, wherein the calcined dolomite includes magnesium oxide and calcium oxide, comprising:

[0083] S1. The calcined dolomite and water are digested to obtain a calcined dolomite suspension;

[0084] S201. The raw gas containing carbon dioxide is stirred and mixed and ultrasonically dispersed at a preset stirring speed and a preset ultrasonic frequency to achieve bubbling of carbon dioxide to obtain fine raw material bubbles; wherein the average size of the fine raw material bubbles is ≤100 μm;

[0085] S3. The fine raw material bubbles and calcined dolomite suspension are carbonized to generate magnesium bicarbonate and calcium carbonate to obtain a mixed suspension; and

[0086] S4. The mixed suspension is subjected to solid-liquid separation to obtain calcium carbonate and a magnesium-containing liquid phase respectively.

[0087] The average size of fine raw material bubbles is 0.1 μm to 100 μm.

[0088] The flow rate of fine raw material bubbles was 1.0 L / min.

[0089] The bubbling treatment time is 50 min.

[0090] The weight of carbon dioxide in the raw gas is 15% of the total weight of the raw gas.

[0091] The temperature of the carbonization reaction is 40°C, and the time of the carbonization reaction is 120 min.

[0092] The preset stirring speed is 300r / min;

[0093] The preset ultrasonic frequency is 30 Hz.

[0094] Ultrasonic dispersion includes 2 ultrasonic working sections and 2 ultrasonic interval sections. The duration of the ultrasonic working section is 5 minutes, and the duration of the ultrasonic interval section is 20 minutes.

[0095] Example 2

[0096] Based on the contents disclosed in Example 1, the following modifications are further made:

[0097] The average size of fine raw material bubbles is 0.1 μm to 100 μm.

[0098] The flow rate of fine raw material bubbles is 1.5 L / min.

[0099] The bubbling treatment time is 32 minutes.

[0100] The weight of carbon dioxide in the raw gas is 20% of the total weight of the raw gas.

[0101] The temperature of the carbonization reaction was 30°C, and the time of the carbonization reaction was 240 min.

[0102] The preset stirring speed is 400r / min;

[0103] The preset ultrasonic frequency is 30 Hz.

[0104] Ultrasonic dispersion includes 2 ultrasonic working sections and 2 ultrasonic interval sections. The duration of the ultrasonic working section is 6 minutes, and the duration of the ultrasonic interval section is 10 minutes.

[0105] Example 3

[0106] Based on the contents disclosed in Example 1, the following modifications are further made:

[0107] The average size of fine raw material bubbles is 0.1 to 60 μm.

[0108] The flow rate of fine raw material bubbles is 0.8 L / min.

[0109] The bubbling treatment time is 24 minutes.

[0110] The weight of carbon dioxide in the raw gas is 25% of the total weight of the raw gas.

[0111] The temperature of the carbonization reaction was 30°C, and the time of the carbonization reaction was 240 min.

[0112] The preset stirring speed is 400r / min;

[0113] The preset ultrasonic frequency is 30 Hz.

[0114] Ultrasonic dispersion includes 2 ultrasonic working sections and 2 ultrasonic interval sections. The duration of the ultrasonic working section is 2 minutes, and the duration of the ultrasonic interval section is 10 minutes.

[0115] Example 4

[0116] Based on the contents disclosed in Example 1, the following modifications are further made:

[0117] The average size of fine raw material bubbles is 0.1 μm to 30 μm.

[0118] The flow rate of fine raw material bubbles is 1.2 L / min.

[0119] The bubbling treatment time was 54 min.

[0120] The weight of carbon dioxide in the raw gas is 30% of the total weight of the raw gas.

[0121] The temperature of the carbonization reaction was 20°C, and the time of the carbonization reaction was 60 min.

[0122] The preset stirring speed is 200r / min;

[0123] The preset ultrasonic frequency is 30 Hz.

[0124] Ultrasonic dispersion includes 2 ultrasonic working sections and 2 ultrasonic interval sections. The ultrasonic working section lasts for 7 minutes, and the ultrasonic interval section lasts for 20 minutes.

[0125] Comparative Example 1

[0126] Based on the contents disclosed in Example 1, the following modifications are further made:

[0127] Without the bubbling treatment, the average bubble size of the raw gas containing carbon dioxide is above 100 μm, and the flow rate of the fine raw gas bubbles is 0 L / min.

[0128] Comparative Example 2

[0129] Based on the contents disclosed in Example 1, the following modifications are further made:

[0130] The flow rate of fine raw material bubbles is 2.0 L / min.

[0131] Comparative Example 3

[0132] Based on the contents disclosed in Example 1, the following modifications are further made:

[0133] No stirring is used for mixing.

[0134] Comparative Example 4

[0135] Based on the contents disclosed in Example 1, the following modifications are further made:

[0136] No ultrasonic dispersion was used.

[0137] Related experiments and effect data:

[0138] The grades of calcium carbonate obtained in each embodiment and comparative example were counted, and the obtained magnesium-containing liquid phase was first pyrolyzed, filtered and dried to obtain basic magnesium carbonate; the basic magnesium carbonate was then calcined at 650° C. for 2 h to obtain a magnesium oxide product; and the grade of the magnesium oxide product was counted, and the results are shown in Table 1.

[0139]

[0140] As can be seen from Table 1, the embodiment of the present application provides a method for separating the calcium and magnesium components of calcined dolomite based on carbon dioxide. The method first subjects the raw gas containing carbon dioxide to bubbling treatment to obtain fine raw gas bubbles, and then mixes the fine raw gas bubbles with the calcined dolomite suspension to promote the fine raw gas bubbles and the calcined dolomite suspension to a gas-liquid-solid three-phase carbonization reaction, which can improve the separation effect of the calcium and magnesium components of the calcined dolomite suspension under a harmless condition, so that the final grades of calcium carbonate and magnesium oxide are respectively above 98%.

[0141] In addition, as shown in Table 1, Comparative Example 1 is not processed by bubbling or Comparative Example 2 uses a fine raw material bubble with a large flow rate. In the crystallization reaction process of the calcined dolomite suspension, the fine raw material bubbles of a larger flow rate and the raw gas without bubbling cannot be effectively combined with magnesium hydroxide and calcium hydroxide, thereby affecting the separation effect of the calcium and magnesium components of the calcined dolomite suspension; In addition, Comparative Example 3 does not use stirring and mixing and Comparative Example 4 does not use ultrasonic dispersion. Based on the carbonization reaction, it is a typical feature of the gas-liquid-solid three-phase reaction, and the uniform dispersion degree of the gas and solid of the gas-liquid-solid three-phase reaction in the liquid is crucial. Therefore, if the operation of stirring and mixing and ultrasonic dispersion is not carried out, the probability of liquid-solid three-phase contact will be greatly reduced, making the carbonization reaction of the calcined dolomite suspension difficult to carry out, thereby affecting the separation effect of the calcium and magnesium components of the calcined dolomite suspension. Therefore, by the various process means combination of the method, the separation effect of the calcium and magnesium components of the calcined dolomite suspension is improved under normal pressure and harmless conditions.

[0142] In summary, the embodiment of the present application provides a method for separating the calcium and magnesium components of calcined dolomite based on carbon dioxide. The method first performs a bubbling treatment on the raw gas containing carbon dioxide, so that the raw gas is converted into fine raw gas bubbles with an average size of ≤100μm, and the fine raw gas bubbles of sufficiently small size and the calcined dolomite suspension undergo a gas-liquid-solid three-phase carbonization reaction to improve the separation effect of the calcium and magnesium components of the calcined dolomite suspension under harmless conditions; in addition, the fine raw gas bubbles can be evenly distributed in the calcined dolomite suspension and attached to the surface of calcium hydroxide, and provide a large number of nucleation sites on the surface of calcium hydroxide to facilitate the formation of calcium carbonate phase, thereby promoting the calcium hydroxide of the dolomite mixed slurry to separate from the liquid phase in the form of calcium carbonate, thereby improving the separation effect of the calcium and magnesium components of the calcined dolomite suspension.

[0143] In addition, an embodiment of the present application provides a method for separating the calcium and magnesium components of calcined dolomite based on carbon dioxide. This method can prepare a relatively high-purity calcium carbonate product, which can meet the requirements of high-end calcium carbonate products, thereby realizing the high-value utilization of calcined dolomite.

[0144] In addition, the embodiment of the present application provides a method for separating the calcium and magnesium components of calcined dolomite based on carbon dioxide. This method has the advantages of easy operation and good safety, which is conducive to the implementation and promotion of the method in industrial production.

[0145] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. It will be apparent to those skilled in the art that various modifications to these embodiments are possible, and the general principles defined in the present application can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown in the present application, but will conform to the widest range consistent with the principles and novel features applied for by the present application.

Claims

1. A method for separating calcium and magnesium components of calcined dolomite based on carbon dioxide, wherein the calcined dolomite comprises magnesium oxide and calcium oxide, the method comprising: Digesting calcined dolomite and water to obtain a calcined dolomite suspension; The raw gas containing carbon dioxide is subjected to bubbling treatment to obtain fine raw gas bubbles; wherein the average size of the fine raw gas bubbles is ≤100 μm; Carrying out a carbonization reaction between the fine raw material bubbles and the calcined dolomite suspension to generate magnesium bicarbonate and calcium carbonate to obtain a mixed suspension; as well as The mixed suspension is subjected to solid-liquid separation to obtain calcium carbonate and a magnesium-containing liquid phase. 2 . The method according to claim 1 , wherein the average size of the fine raw material bubbles is 0.1 μm to 100 μm.

3. The method according to claim 1, wherein the flow rate of the fine raw material bubbles is 0.1 L / min to 1.5 L / min.

4. The method according to any one of claims 1 to 3, wherein the bubbling treatment time is ≥ 12 min. 5 . The method according to claim 1 , wherein the weight of carbon dioxide in the raw gas is ≥ 5% of the total weight of the raw gas.

6. The method according to claim 1, wherein the temperature of the carbonization reaction is 0°C to 50°C, and the time of the carbonization reaction is 10 min to 240 min.

7. The method according to claim 1, wherein the raw gas containing carbon dioxide is subjected to bubbling treatment to obtain fine raw gas bubbles, comprising the steps of: At a preset stirring speed and a preset ultrasonic frequency, the raw material gas containing carbon dioxide is simultaneously stirred and mixed and ultrasonically dispersed so that the carbon dioxide forms bubbles to obtain fine raw material bubbles.

8. The method according to claim 7, wherein the preset stirring speed is ≥50 r / min; and / or The preset ultrasonic frequency is ≥20 Hz.

9. The method according to claim 7, wherein the ultrasonic dispersion comprises a plurality of ultrasonic working segments and a plurality of ultrasonic interval segments, and the time t1 of the ultrasonic working segment and the time t2 of the ultrasonic interval segment satisfy the relationship: t1:t2=1:(3-10).

10. The method according to claim 9, wherein the duration of the ultrasonic working section is 1 min to 10 min, and the duration of the ultrasonic interval section is 10 min to 30 min.

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