Preparation method of heavy magnesium water

Abstract

The invention discloses a preparation method of heavy magnesium water, which comprises the following steps: S1, mixing light burning powder and process water to obtain initial slurry; s2, the initial slurry is introduced into a first-stage reactor, and first-stage slurry is formed through a first-stage jet flow enhanced leaching reaction; s3, the first-stage slurry is introduced into a second-stage reactor, and second-stage slurry is formed through a second-stage jet flow enhanced leaching reaction; and S4, treating the secondary slurry to obtain the heavy magnesium water. S2, introducing a first process gas into the first-stage reactor; and S3, introducing a second process gas into the second-stage reactor. The reaction pressure in the first-stage reactor is controlled within the range of 0.05-1.0 MPa, the reaction pressure in the second-stage reactor is controlled within the range of 0.3-1.0 MPa, and the reaction pressure value is a relative pressure value; and controlling the pH values in the first-stage reactor and the second-stage reactor to be in stepped distribution, so that the pH value in the first-stage reactor is greater than the pH value in the second-stage reactor. The preparation method realizes resource utilization of calcining flue gas of magnesite, dolomite and other magnesium ores.

Description

Technical Field

[0001] This invention belongs to the field of inorganic material preparation technology, and particularly relates to a method for preparing heavy magnesium water. Background Technology

[0002] Magnesium bicarbonate solution (i.e., magnesium bicarbonate aqueous solution) is an important intermediate raw material for the preparation of magnesium materials such as high-purity magnesium oxide and magnesium carbonate. The industrial preparation of magnesium bicarbonate solution generally uses magnesium ores such as magnesite or dolomite as raw materials, which are calcined, digested and carbonized to produce magnesium bicarbonate solution.

[0003] my country boasts some of the world's largest reserves of magnesium ore, including magnesite. However, high-grade ore (MgO content above 45%) is facing increasing depletion, while low-grade ore and tailings, due to their high impurity content, present significant technical challenges in purification and utilization processes such as high energy consumption, substantial pollution, and uncontrollable magnesium leaching rates. These technological bottlenecks hinder the industrial-scale purification and utilization of the large stockpiles of low-grade ore and tailings, resulting in a magnesium resource utilization rate of less than 40% in my country.

[0004] On the other hand, traditional calcination purification processes separate flue gas treatment from mineral processing, resulting in CO2 utilization rates below 30%, high carbon emission intensity, and failure to achieve carbon closure. Meanwhile, my country's industrial sector emits over 2 billion tons of CO2 annually, a massive amount. Regarding the reuse of this emitted CO2, traditional technologies (such as amine methods, membrane separation, and adsorption methods) generally require filtration, heat exchange, and compression of flue gas or waste gas, which is not only energy-intensive and requires large investments in equipment, but also has low utilization rates, leading to a waste of carbon resources. Summary of the Invention

[0005] To address the aforementioned problems, this invention proposes a method for preparing heavy magnesium water, which not only efficiently prepares high-quality heavy magnesium water but also realizes the resource utilization of calcination flue gas from magnesium ores such as magnesite and dolomite, achieving a closed-loop technical effect of carbon reduction and product preparation.

[0006] This invention provides a method for preparing heavy magnesium hydrate, comprising: S1, mixing light calcined powder and process water to obtain an initial slurry; S2, passing the initial slurry into a primary reactor and undergoing a primary jet-enhanced leaching reaction to form a primary slurry; S3, passing the primary slurry into a secondary reactor and undergoing a secondary jet-enhanced leaching reaction to form a secondary slurry; and S4, processing the secondary slurry to obtain heavy magnesium hydrate.

[0007] Among them, lightly calcined powder refers to magnesium ore such as magnesite, magnesite tailings or dolomite obtained by calcination. The calcination mentioned here can be calcination in a suspension kiln, calcination in a direct-fired rotary kiln or calcination in an indirect-fired rotary kiln. In a preferred embodiment, calcination in a suspension kiln is used.

[0008] S2 includes introducing a first process gas into the primary reactor; S3 includes introducing a second process gas into the secondary reactor; controlling the reaction pressure in the primary reactor within the range of 0.05 to 1.0 MPa and the reaction pressure in the secondary reactor within the range of 0.3 to 1.0 MPa, the reaction pressure values ​​being relative pressure values; controlling the pH values ​​in the primary and secondary reactors to exhibit a stepped distribution, such that the pH value in the primary reactor is greater than the pH value in the secondary reactor.

[0009] In one possible implementation, in S1, the lightly calcined powder can be mixed directly with process water, or it can be pretreated before being mixed with process water.

[0010] In one possible implementation, both the first process gas and the second process gas contain carbon dioxide; the first process gas includes gas exiting from the secondary reactor and / or tail gas discharged from the secondary reactor, or the second process gas includes gas exiting from the primary reactor and / or tail gas discharged from the primary reactor.

[0011] In one possible implementation, both the primary and secondary reactors are equipped with gas-liquid couplers, and ejectors are installed on the gas-liquid couplers. The initial slurry and the first process gas, as well as the primary slurry and the second process gas, are coupled in the gas-liquid couplers in the primary and secondary reactors, respectively, and then ejected through the ejectors to achieve jet enhancement.

[0012] In one possible implementation, the first or second process gas includes at least one of the calcination flue gas generated during the carbonate calcination process and the combustion exhaust gas generated during the gas combustion process, so that the calcination flue gas and combustion exhaust gas can be directly utilized as resources. In a preferred embodiment, the calcination flue gas used is the calcination flue gas generated during the calcination process of magnesium ores such as magnesite, magnesite tailings, or dolomite.

[0013] In one possible implementation, the first process gas is directly the calcination flue gas generated during the carbonate calcination process, and is introduced directly into the first-stage reactor through an ejector without any treatment.

[0014] In one possible implementation, the first process gas is calcination flue gas generated during the carbonate calcination process, which is then introduced into the primary reactor via a jet injector after heat exchange and / or purification.

[0015] In one possible implementation, the second process gas is directly the calcination flue gas generated during the carbonate calcination process, and is introduced directly into the secondary reactor through an ejector without any treatment.

[0016] In one possible implementation, the second process gas is calcination flue gas generated during the carbonate calcination process, which is then heat-exchanged and / or purified before being introduced into the secondary reactor via an ejector.

[0017] In one possible implementation, a first gas-liquid separator is provided between the primary reactor and the secondary reactor. After the initial slurry flows out of the primary reactor, it enters the first gas-liquid separator for gas-liquid separation to remove the gas mixed in the initial slurry. After gas-liquid separation, a portion of the initial slurry is accelerated by a jet pump and then returned to the primary reactor. This portion of the initial slurry continuously circulates between the primary reactor and the first gas-liquid separator. The initial slurry undergoes a primary jet-enhanced leaching reaction as it flows through the primary reactor. The other portion of the initial slurry enters the secondary reactor as the primary slurry.

[0018] In one possible implementation, a second gas-liquid separator is installed downstream of the secondary reactor. After the primary slurry flows out of the secondary reactor, it enters the second gas-liquid separator for gas-liquid separation to remove the gas mixed in the primary slurry. After gas-liquid separation, the primary slurry is accelerated by a jet pump and then returned to the secondary reactor. The primary slurry continuously circulates between the secondary reactor and the second gas-liquid separator. As the primary slurry flows through the secondary reactor, it undergoes a secondary jet-enhanced leaching reaction. After the secondary jet-enhanced leaching reaction of the primary slurry in the secondary reactor reaches the reaction time, a secondary slurry is formed. The secondary slurry overflows from the secondary reactor and is treated in S4 to obtain heavy magnesium water.

[0019] In one possible implementation, in S2, the initial slurry is continuously fed into the primary reactor.

[0020] In one possible implementation, the secondary slurry in S3 flows out of the secondary reactor continuously and then passes through the treatment in S4 continuously to obtain heavy magnesium water.

[0021] In one possible implementation, S4 includes at least one of impurity removal treatment of the secondary slurry and solid-liquid separation.

[0022] In one possible implementation, the reaction time for both the primary jet-enhanced leaching reaction and the secondary jet-enhanced leaching reaction is in the range of 10–150 min; the magnesium oxide content in the primary slurry is 5–200 g / L, and the magnesium oxide content in the secondary slurry is 3–150 g / L, based on magnesium oxide.

[0023] In one possible implementation, the pH value in the primary reactor is controlled within the range of 7-12, the pH value in the secondary reactor is controlled within the range of 6-9, and the pH value in the primary reactor is made greater than the pH value in the secondary reactor.

[0024] In one possible implementation, S4 includes feeding the secondary slurry into a tertiary reactor for a tertiary jet-enhanced leaching reaction, and introducing a third process gas into the tertiary reactor. The first process gas is directly the calcination flue gas generated during the carbonate calcination process, without any treatment, and is directly introduced into the first-stage reactor through an ejector. Alternatively, the third process gas is directly the calcination flue gas generated during the carbonate calcination process, without any treatment, and is directly introduced into the tertiary reactor through an ejector.

[0025] In one possible implementation, a third gas-liquid separator is installed downstream of the tertiary reactor. After the secondary slurry flows out of the tertiary reactor, it enters the third gas-liquid separator for gas-liquid separation to remove the gas mixed in the secondary slurry. After gas-liquid separation, the secondary slurry is accelerated by a jet pump and then flows back to the tertiary reactor. The secondary slurry continuously circulates between the tertiary reactor and the third gas-liquid separator. When the secondary slurry flows through the tertiary reactor, it continuously undergoes a tertiary jet-enhanced leaching reaction. After the tertiary jet-enhanced leaching reaction of the secondary slurry in the tertiary reactor reaches the reaction time, a tertiary slurry is formed. The tertiary slurry overflows from the tertiary reactor to obtain heavy magnesium water.

[0026] In one possible implementation, after the tertiary slurry overflows from the tertiary reactor, it needs to undergo post-treatment, which includes at least one of impurity removal and solid-liquid separation of the tertiary slurry.

[0027] In one possible implementation, the reaction time of the three-stage jet-enhanced leaching reaction is in the range of 10 to 150 minutes.

[0028] In one possible implementation, the pH value in the secondary reactor is controlled to be higher than that in the tertiary reactor.

[0029] The beneficial effects of this invention are: This invention uses calcined light-burnt powder to make a slurry, which is then used as an adsorbent to absorb carbon dioxide from the calcination flue gas or combustion tail gas introduced into the reactor. After reaction, it produces industrially usable heavy magnesium water, simultaneously achieving carbon dioxide recovery and industrial reuse in one step, turning waste into treasure. It provides a practical integrated solution for "tail gas treatment - mineral processing - solid waste utilization," realizing the resource utilization of calcination flue gas and combustion tail gas from magnesite, dolomite, and other magnesium ores, achieving a closed loop of carbon reduction and product preparation. It also saves the significant energy consumption required for traditional technologies to reuse calcination flue gas and combustion tail gas emissions. Taking a magnesite plant as an example, using the technology of this application can reduce CO2 emissions by more than 90%, save energy by about 40%, achieve 100% comprehensive utilization of solid waste, and reduce the cost per ton of product by about 28%, demonstrating significant environmental and economic benefits.

[0030] This application employs a jet-enhanced leaching method with at least two stages to strengthen gas-liquid turbulent mixing. Simultaneously, by controlling the pH value of the reaction environment in the multi-stage reactor to exhibit a specific stepped distribution, the CO2 dissolution rate is increased to more than three times that of traditional mechanical stirring leaching, thereby improving reaction efficiency and promoting magnesium leaching. The magnesium leaching rate can reach over 95%, significantly reversing the low utilization rate of low-grade ores and tailings. The preparation method of this invention overcomes the technical difficulties of high energy consumption, high pollution, and uncontrollable magnesium leaching rate in the purification and utilization of low-grade ores and tailings. It breaks through the traditional model and concept of "high energy consumption, high pollution, and low added value" in the purification of low-grade minerals, providing a new path for the efficient utilization of low-grade magnesium ores. This allows large accumulations of low-grade ores and tailings to have industrial utilization value after industrial purification, which is beneficial to improving the utilization rate of magnesium resources in my country.

[0031] The above general description and the description below are exemplary and illustrative only and are not intended to limit this application. Attached Figure Description

[0032] One or more embodiments are illustrated by way of example with reference to the accompanying drawings. These illustrations and drawings do not constitute a limitation on the embodiments. Elements having the same reference numerals in the drawings are shown as similar elements, and the drawings do not constitute a limitation of scale. Wherein: Figure 1 This is a schematic flowchart of a method for preparing heavy magnesium water provided in an embodiment of this application.

[0033] Figure 2 This is a schematic diagram of the structural composition of one embodiment of the heavy magnesium water preparation system involved in this application.

[0034] Figure label: 1. Slurry preparation device; 2. Primary reactor; 3. Secondary reactor; 4. Gas-liquid coupler; 5. Ejector; 6. Solid-liquid separation device; 7. Impurity removal device; 8. First gas-liquid separator; 9. Jet pump; 10. Discharge pump; 11. Second gas-liquid separator. Detailed Implementation

[0035] The specific embodiments of the present invention are further described below with reference to the accompanying drawings. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. In the following description, for ease of explanation, several details are used to provide a full understanding of the invention. However, the invention can still be practiced without these details. In other instances, well-known structures and apparatuses may be shown in a simplified manner to simplify the drawings.

[0036] The terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of the invention described herein.

[0037] In this invention, the terms "upper," "lower," "inner," "middle," "outer," "front," and "rear," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing this invention and are not intended to limit the indicated device, element, or component to having a specific orientation, or to require it to be constructed and operated in a specific orientation. Furthermore, some of the aforementioned terms may have other meanings besides indicating orientation or positional relationship; for example, the term "upper" may in some cases indicate a dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this invention based on the specific circumstances.

[0038] Furthermore, the terms "set up," "connect," and "fix" should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0039] like Figure 1 As shown in the embodiments, this application provides a method for preparing hydrated magnesium hydroxide. This preparation method can be implemented using a hydrated magnesium hydroxide preparation system. One embodiment of this hydrated magnesium hydroxide preparation system is as follows: Figure 2 As shown, it includes a slurry preparation device 1, a primary reactor 2, a secondary reactor 3, and a solid-liquid separation device 6, wherein the secondary reactor 3 is located downstream of the primary reactor 2.

[0040] The preparation method specifically includes: S1, mix lightly calcined powder and process water to obtain initial slurry.

[0041] Among them, lightly calcined powder refers to magnesium ore such as magnesite, magnesite tailings or dolomite obtained by calcination. The calcination mentioned here can be calcination in a suspension kiln, calcination in a direct-fired rotary kiln or calcination in an indirect-fired rotary kiln. In a preferred embodiment, calcination in a suspension kiln is used.

[0042] In one possible implementation, in S1, the lightly calcined powder can be mixed directly with process water, or it can be pre-treated before being mixed with process water. For example, this pre-treatment includes pre-removal of impurities, crushing, etc.

[0043] In one possible implementation, the mixing of light-burned powder and process water is achieved by preparing the light-burned powder and process water into an initial slurry with mechanical stirring using a slurry preparation device to obtain an initial slurry of the desired concentration. For example, the mixing is carried out at room temperature and pressure, and the preparation time is 0.2 h to 3 h.

[0044] S2, the initial slurry is fed into the primary reactor and undergoes a primary jet-enhanced leaching reaction to form the primary slurry.

[0045] S3, the primary slurry is fed into the secondary reactor, and after a secondary jet-enhanced leaching reaction, a secondary slurry is formed.

[0046] S2 includes introducing a first process gas into the primary reactor; S3 includes introducing a second process gas into the secondary reactor.

[0047] In one possible implementation, both the first process gas and the second process gas contain carbon dioxide; the first process gas includes gas exiting from the secondary reactor and / or tail gas discharged from the secondary reactor, or the second process gas includes gas exiting from the primary reactor and / or tail gas discharged from the primary reactor.

[0048] In one possible implementation, the first or second process gas includes at least one of the calcination flue gas generated during the carbonate calcination process and the combustion exhaust gas generated during the gas combustion process, so that the calcination flue gas and combustion exhaust gas can be directly utilized as resources. For example, the carbonate includes magnesite, magnesite tailings, or dolomite and other magnesium ores.

[0049] In a preferred embodiment, the calcination flue gas used is the calcination flue gas generated during the calcination process of magnesium ores such as magnesite, magnesite tailings, or dolomite.

[0050] In one possible implementation, both the primary reactor and the secondary reactor are equipped with gas-liquid couplers 4, and jetters 5 are installed on the gas-liquid couplers; the initial slurry and the first process gas, as well as the primary slurry and the second process gas, are coupled in the gas-liquid couplers in the primary reactor and the secondary reactor, respectively, and then ejected through the jetters to achieve jet enhancement.

[0051] In one possible implementation, the first process gas is directly the calcination flue gas generated during the carbonate calcination process, and is introduced directly into the primary reactor through an ejector without any treatment. Alternatively, the calcination flue gas undergoes heat exchange and / or purification before being introduced into the primary reactor through an ejector.

[0052] In one possible implementation, the second process gas is directly the calcination flue gas generated during the carbonate calcination process, and is introduced directly into the secondary reactor through an ejector without any treatment. Alternatively, the calcination flue gas undergoes heat exchange and / or purification before being introduced into the secondary reactor through an ejector.

[0053] The reaction pressure in the primary reactor is controlled within the range of 0.05–1.0 MPa, and the reaction pressure in the secondary reactor is controlled within the range of 0.3–1.0 MPa. The reaction pressure values ​​are relative pressure values.

[0054] The pH values ​​in the primary and secondary reactors are controlled to exhibit a stepped distribution, with the pH value in the primary reactor being higher than that in the secondary reactor.

[0055] In one possible implementation, the pH value in the primary reactor is controlled within the range of 7-12, the pH value in the secondary reactor is controlled within the range of 6-9, and the pH value in the primary reactor is made greater than the pH value in the secondary reactor.

[0056] In one possible implementation, the reaction times for both the primary and secondary jet-enhanced leaching reactions are in the range of 10–150 min; the magnesium oxide content in the primary slurry is 5–200 g / L, and the magnesium oxide content in the secondary slurry is 3–150 g / L. For example, the reaction times for both primary and secondary jet-enhanced leaching reactions are in the range of 10–60 min.

[0057] S4 is used to process the secondary slurry to obtain heavy magnesium water.

[0058] In one possible implementation, S4 includes at least one of impurity removal and solid-liquid separation of the secondary slurry. Figure 2 In the embodiment shown, a solid-liquid separation device 6 is provided downstream of the secondary reactor 3 for solid-liquid separation of the secondary slurry from the secondary reactor; and a purification device 7 is provided downstream of the solid-liquid separation device 6 for purification of the secondary slurry.

[0059] In another possible implementation, the impurity removal device is located between the secondary reactor and the solid-liquid separation device.

[0060] In one possible implementation, S4 includes solid-liquid separation treatment, and the filter residue obtained from solid-liquid separation is used to prepare cement admixtures for utilization, forming a closed-loop design of the process chain of "calcination flue gas / tail gas treatment - mineral processing - solid waste utilization".

[0061] In one possible implementation, a first gas-liquid separator 8 is installed between the primary reactor 2 and the secondary reactor 3. The initial slurry flows out of the primary reactor and enters the first gas-liquid separator for gas-liquid separation, removing any mixed gases from the initial slurry. The primary reactor has a first outlet and a second outlet. After gas-liquid separation, a portion of the initial slurry flows out through the first outlet, is accelerated by a jet pump 9, and then flows back to the primary reactor. This portion of the initial slurry continuously circulates between the primary reactor and the first gas-liquid separator, continuously undergoing the primary jet-enhanced leaching reaction as it flows through the primary reactor. Another portion of the initial slurry flows out through the second outlet and enters the secondary reactor as primary slurry.

[0062] In one possible implementation, a discharge pump 10 is provided downstream of the second outlet to drive the primary slurry flowing out of the second outlet into the secondary reactor.

[0063] In one possible implementation, a second gas-liquid separator 11 is installed downstream of the secondary reactor 3. After exiting the secondary reactor, the primary slurry enters the second gas-liquid separator for gas-liquid separation, removing any mixed gases from the primary slurry. The secondary reactor is equipped with a third outlet. The primary slurry, after gas-liquid separation, flows out through the third outlet, is accelerated by a jet pump, and then flows back to the secondary reactor. The primary slurry continuously circulates between the secondary reactor and the second gas-liquid separator, undergoing a continuous secondary jet-enhanced leaching reaction as it flows through the secondary reactor. After the secondary jet-enhanced leaching reaction in the secondary reactor reaches the required reaction time, a secondary slurry is formed. An overflow port is provided on the secondary reactor, through which the secondary slurry flows out of the secondary reactor and, after treatment in step S4, yields heavy magnesium water.

[0064] In one possible implementation, in S2, the initial slurry is continuously fed into the primary reactor.

[0065] In one possible implementation, the secondary slurry in S3 flows out of the secondary reactor continuously and then passes through the treatment in S4 continuously to obtain heavy magnesium water.

[0066] In one possible implementation, S4 includes feeding the secondary slurry into a tertiary reactor for a tertiary jet-enhanced leaching reaction, and introducing a third process gas into the tertiary reactor. The first process gas is directly the calcination flue gas generated during the carbonate calcination process, without any treatment, and is directly introduced into the first-stage reactor through an ejector. Alternatively, the third process gas is directly the calcination flue gas generated during the carbonate calcination process, without any treatment, and is directly introduced into the tertiary reactor through an ejector.

[0067] In one possible implementation, a third gas-liquid separator is installed downstream of the tertiary reactor. After the secondary slurry flows out of the tertiary reactor, it enters the third gas-liquid separator for gas-liquid separation to remove the gas mixed in the secondary slurry. After gas-liquid separation, the secondary slurry is accelerated by a jet pump and then flows back to the tertiary reactor. The secondary slurry continuously circulates between the tertiary reactor and the third gas-liquid separator. When the secondary slurry flows through the tertiary reactor, it continuously undergoes a tertiary jet-enhanced leaching reaction. After the tertiary jet-enhanced leaching reaction of the secondary slurry in the tertiary reactor reaches the reaction time, a tertiary slurry is formed. The tertiary slurry overflows from the tertiary reactor to obtain heavy magnesium water.

[0068] In one possible implementation, after the tertiary slurry overflows from the tertiary reactor, it needs to undergo post-treatment, which includes at least one of impurity removal and solid-liquid separation of the tertiary slurry.

[0069] In one possible implementation, the reaction time of the three-stage jet-enhanced leaching reaction is in the range of 10 to 150 minutes.

[0070] In one possible implementation, the pH value in the secondary reactor is controlled to be higher than that in the tertiary reactor.

[0071] In one possible implementation, the reaction temperature of each stage of jet-enhanced leaching reaction is in the range of 20-50°C.

[0072] The present invention will be further described below with reference to specific embodiments and comparative examples.

[0073] Example 1

[0074] No. 1 light calcined powder was obtained by calcining No. 1 magnesite ore.

[0075] Composition of No. 1 magnesite ore (mass fraction): MgO 45.25%, CaO 0.07%, SiO2 3.77%, Fe2O3 0.21%, Al2O3 1.28%.

[0076] Composition of No. 1 light calcined powder (mass fraction): MgO 85.2%, CaO 0.14%, SiO2 7.1%, Fe2O3 0.4%, Al2O3 2.4%.

[0077] 250 kg of No. 1 light calcined powder (containing approximately 213 kg of magnesium oxide) was mixed with process water to obtain 20,000 kg of initial slurry. The initial slurry was then fed into a primary reactor for a primary jet-enhanced leaching reaction to form the primary slurry. The carbon dioxide in the primary reactor was obtained from the carbon dioxide tail gas emitted from the secondary reactor. The primary jet-enhanced leaching reaction was controlled at a temperature of 25°C, a pressure of 0.25 MPa, a pH of 8.5–9.5, and a reaction time of 30 min.

[0078] The primary slurry is fed into a secondary reactor for a secondary jet-enhanced leaching reaction to form a secondary slurry. The carbon dioxide in the secondary reactor comes from the calcination flue gas. The reaction temperature of the secondary jet-enhanced leaching reaction is controlled at 25℃, the reaction pressure at 0.45MPa, the pH value at 6.5–7.5, and the reaction time at 30 min.

[0079] After solid-liquid separation and purification, the secondary slurry yielded 20,350 kg of hydrated magnesium oxide. Testing revealed that the hydrated magnesium oxide contained 10.16 g / L of magnesium, 2.06 mg / L of calcium oxide, and 1.19 mg / L of iron oxide, with a magnesium leaching rate of 97.02%. It consumed 501 kg of carbon dioxide (theoretically 451 kg), achieving a carbon dioxide utilization rate of 90.02%.

[0080] Comparative Example 1 250 kg of the same No. 1 light calcined powder (containing approximately 213 kg of magnesium oxide) as in Example 1 and 20,000 kg of process water were used to prepare a slurry. This slurry was then subjected to a digestion reaction to obtain a digested slurry. The digested slurry was then subjected to a carbonization reaction in a mechanically stirred tank to obtain a carbonized slurry. After solid-liquid separation and purification, 20,210 kg of heavy magnesium water was obtained. Testing revealed that the heavy magnesium water contained 7.92 g / L of magnesium oxide, 13.80 mg / L of calcium oxide, and 10.51 mg / L of iron oxide, with a magnesium leaching rate of 75.11%. 615 kg of carbon dioxide was consumed (theoretically 349 kg), resulting in a carbon dioxide utilization rate of approximately 56.75%.

[0081] For Magnesite No. 1 with a magnesium oxide content of approximately 45%, Comparative Example 1 used a conventional digestion-carbonization reaction method to prepare heavy magnesium hydrate from the lightly calcined powder obtained from the magnesite. During the preparation process, the magnesium leaching rate was only 75.11%, and the magnesium content in the obtained heavy magnesium hydrate was low, less than 8 g / L.

[0082] Example 1 employs the jet-enhanced leaching method of the present invention, and sets up two or more stages of jet-enhanced leaching to enhance gas-liquid turbulent mixing. At the same time, the pH value of the reaction environment in the primary and secondary reactors is controlled to present a specific step distribution. The staged jet-enhanced leaching effect and the pH step distribution effect produce a coupling effect, which increases the CO2 dissolution rate to more than three times that of traditional mechanical stirring leaching, improves the reaction efficiency, promotes magnesium leaching, and achieves a magnesium leaching rate of about 97%. The magnesium content in the obtained heavy magnesium water is increased to a high level of about 10 g / L. At the same time, this coupling effect also inhibits the dissolution of light calcined powder impurities, and controls the content of impurities such as Ca and Fe in the heavy magnesium water to an extremely low level. The obtained heavy magnesium water meets high quality standards in terms of both magnesium content and impurity content.

[0083] Example 2

[0084] No. 2 light calcined powder was obtained by calcining No. 2 magnesite tailings.

[0085] Composition of No. 2 magnesite tailings (mass fraction): MgO 42.7%, CaO 4.85%, SiO2 6.1%, Fe2O3 0.52%, Al2O3 0.75%.

[0086] Composition of No. 2 light calcined powder (mass fraction): MgO 76.69%, CaO 8.71%, SiO2 10.96%, Fe2O3 0.93%, Al2O3 1.35%.

[0087] 278 kg of No. 2 light calcined powder (containing approximately 213 kg of magnesium oxide) and 20,000 kg of process water were mixed and subjected to the same first-stage and second-stage jet-enhanced leaching reactions as in Example 1, yielding 20,300 kg of heavy magnesium leaching solution. Testing revealed that the magnesium content (calculated as magnesium oxide) in this heavy magnesium leaching solution was 9.47 g / L, the calcium oxide content was 5.06 mg / L, and the iron oxide content was 1.92 mg / L, with a magnesium leaching rate of 90.29%. 476 kg of carbon dioxide was consumed (theoretically 420 kg), resulting in a carbon dioxide utilization rate of 88.24%.

[0088] Comparative Example 2 278 kg of the same No. 2 light calcined powder (containing approximately 213 kg of magnesium oxide) as in Example 2 was taken and mixed with process water to form a slurry of 20,000 kg. This slurry was then subjected to a digestion reaction to obtain a digested slurry. The digested slurry was then subjected to a carbonization reaction in a mechanically stirred tank to obtain a carbonized slurry. After solid-liquid separation and purification, 20,240 kg of heavy magnesium water was obtained. Testing revealed that the heavy magnesium water contained 6.78 g / L of magnesium oxide, 15.34 mg / L of calcium oxide, and 20.66 mg / L of iron oxide, with a magnesium leaching rate of 64.42%. 480 kg of carbon dioxide was consumed (theoretically 300 kg), resulting in a carbon dioxide utilization rate of approximately 49.18%.

[0089] The magnesium content in No. 2 magnesite tailings is further reduced, and the content of impurities such as Ca and Fe is high. If the conventional digestion-carbonization reaction method described in Comparative Example 2 is used, the magnesium leaching rate is only 64.42%, and the magnesium content in the obtained heavy magnesium water is even lower, less than 7 g / L. Moreover, the content of impurities such as Ca and Fe in the heavy magnesium water is seriously excessive, and the obtained heavy magnesium water cannot be used. Thus, low-grade ores and tailings similar to No. 2 magnesite tailings lose their application value in the chemical industry.

[0090] Example 2 employs the jet-enhanced leaching method of the present invention, and sets up two or more stages of jet-enhanced leaching to enhance gas-liquid turbulent mixing. At the same time, the pH value of the reaction environment in the primary and secondary reactors is controlled to present a specific step distribution. The staged jet-enhanced leaching effect and the pH step distribution effect produce a coupling effect, which increases the CO2 dissolution rate to more than three times that of traditional mechanical stirring leaching, improves the reaction efficiency, promotes magnesium leaching, and the magnesium leaching rate still reaches a high level of about 90%. The magnesium content in the obtained heavy magnesium water is increased to a high level of close to 10 g / L. At the same time, this coupling effect also inhibits the dissolution of light calcined powder impurities, and controls the content of impurities such as Ca and Fe in the heavy magnesium water to an extremely low level, producing high-quality heavy magnesium water that meets industrial application standards. This makes such low-grade ores and tailings ores have renewed application value in the chemical field, and helps to improve the utilization rate of magnesium resources in my country.

[0091] On the other hand, in the implementation of Examples 1 and 2 using the technology of the present invention, the carbon dioxide utilization rate reached 90.02% and 88.24% respectively, which were significantly improved compared with Comparative Example 1 and Comparative Example 2, effectively reducing carbon emissions and improving the carbon dioxide recovery and utilization rate.

[0092] Furthermore, and more importantly, a comparison of the data from the examples and comparative examples shows that, to prepare heavy magnesium hydrate of the same magnesium content grade, the preparation method of this invention can save approximately 20-30% of the amount of lightly calcined magnesite powder of the same grade, or further reduce the magnesium content requirements in the magnesite ore used. This greatly improves the utilization rate of magnesium resources and saves magnesium resource consumption. In particular, it reverses the low utilization rate of low-grade ore and tailings, and breaks through the technical bottlenecks encountered in the purification and utilization of low-grade ore and tailings, such as high energy consumption, high pollution, and uncontrollable magnesium leaching rate. It reverses the traditional model and concept of "high energy consumption, high pollution, and low added value" for the purification of low-grade minerals, and provides a new path for the efficient utilization of low-grade magnesium ore. This allows large amounts of accumulated low-grade ore and tailings to regain industrial utilization value after being purified and prepared using the original industrial purification method of this application.

[0093] The embodiments of the present invention are not limited to the structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the present invention is limited only by the appended claims.

Claims

1. A method for preparing heavy magnesium water, characterized by, The method comprises the following steps: S1, mixing the light-burned powder and process water to obtain initial slurry; S2, passing the initial slurry into a first reactor to perform a first jet-enhanced leaching reaction to form first-stage slurry; S3, passing the first-stage slurry into a second reactor to perform a second jet-enhanced leaching reaction to form second-stage slurry; S4, processing the second-stage slurry to obtain heavy magnesium water; S2 comprises passing a first process gas into the first reactor; S3 comprises passing a second process gas into the second reactor; the reaction pressure in the first reactor is controlled to be within a range of 0.05-1.0 MPa, and the reaction pressure in the second reactor is controlled to be within a range of 0.3-1.0 MPa, wherein the reaction pressure values are relative pressure values; the pH values in the first reactor and the second reactor are controlled to present a step distribution, and the pH value in the first reactor is greater than the pH value in the second reactor.

2. The method of preparing heavy magnesia water according to claim 1, characterized by, The first process gas and the second process gas both contain carbon dioxide; the first process gas comprises gas flowing out of the second reactor and / or tail gas discharged from the second reactor, or the second process gas comprises gas flowing out of the first reactor and / or tail gas discharged from the first reactor.

3. The method of preparing heavy magnesia water according to claim 1, characterized by, The first reactor and the second reactor are both provided with gas-liquid couplers, and the gas-liquid couplers are provided with jet devices; the initial slurry and the first process gas, and the first-stage slurry and the second process gas are coupled in the gas-liquid couplers in the first reactor and the second reactor respectively and then jetted out through the jet devices to realize jet enhancement.

4. The method of preparing heavy magnesia water according to claim 1, characterized by, The first process gas or the second process gas comprises at least one of calcination flue gas generated in a carbonic acid salt calcination process and combustion tail gas generated in a gas combustion process.

5. The method of preparing heavy magnesia water according to claim 1, characterized by, A first gas-liquid separator is arranged between the first reactor and the second reactor, the initial slurry flows out of the first reactor and enters the first gas-liquid separator to perform gas-liquid separation and remove the mixed gas in the initial slurry; after the gas-liquid separation, part of the initial slurry is accelerated by a jet pump and then flows back to the first reactor, the part of the initial slurry continuously circulates between the first reactor and the first gas-liquid separator, and the initial slurry continuously performs the first jet-enhanced leaching reaction when flowing through the first reactor; the other part of the initial slurry enters the second reactor as the first-stage slurry.

6. The method of preparing heavy magnesia water according to claim 1, characterized by, A second gas-liquid separator is arranged downstream of the second reactor, the first-stage slurry flows out of the second reactor and enters the second gas-liquid separator to perform gas-liquid separation and remove the mixed gas in the first-stage slurry; after the gas-liquid separation, the first-stage slurry is accelerated by a jet pump and then flows back to the second reactor, the first-stage slurry continuously circulates between the second reactor and the second gas-liquid separator, and the first-stage slurry continuously performs the second jet-enhanced leaching reaction when flowing through the second reactor; after the second jet-enhanced leaching reaction in the second reactor reaches a reaction time, the first-stage slurry forms the second-stage slurry.

7. The method of preparing heavy magnesium water according to any one of claims 1 to 6, characterized in that, S4 comprises at least one of impurity removal processing and solid-liquid separation on the second-stage slurry.

8. The method of preparing heavy magnesia water according to claim 1, characterized by, S4 comprises passing the second-stage slurry into a third reactor to perform a third jet-enhanced leaching reaction and passing a third process gas into the third reactor.

9. The method of preparing heavy magnesia water according to claim 1, characterized by, In S2, the initial slurry is passed into the first reactor in a continuous manner.

10. The method of preparing heavy magnesia water according to claim 1, characterized by, The secondary slurry in S3 is continuously discharged from the secondary reactor and continuously treated in S4 to obtain heavy magnesium water.

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