Magnesium smelting method, modified magnesium slag and slag silicate cement

Abstract

The invention provides a magnesium smelting method, modified magnesium slag and slag silicate cement. The magnesium smelting method comprises the following steps: mixing dolomite, fluorite powder, ferrosilicon powder and primary aluminum ash to obtain a mixture; the mixture is subjected to a reduction reaction under the vacuum and heating conditions, and crude magnesium and reducing slag are prepared; and rapidly cooling the reducing slag by adopting an activating solution to prepare the modified magnesium slag. According to the method, the primary aluminum ash, the dolomite, the fluorite powder and the ferrosilicon powder are mixed to serve as production raw materials, all the substances interact, the magnesium reduction yield can be increased, the content of magnesium oxide in the modified magnesium slag can be reduced, and therefore the influence of magnesium oxide on the activity of the magnesium reduction slag is reduced; and meanwhile, the metal magnesium slag is rapidly cooled by using an activating solution, so that calcium silicate in the magnesium slag is converted into beta-Ca2SiO3 with gel properties, and the activity of the modified magnesium slag is improved.

Description

Technical Field

[0001] This application relates to the field of metal smelting technology, and in particular to a magnesium smelting method, modified magnesium slag, and slag silicate cement. Background Technology

[0002] The most commonly used method for producing metallic magnesium in my country is the Pidgeon process. Traditional Pidgeon process magnesium smelting suffers from high energy consumption and high carbon emissions, and particularly generates a significant amount of waste slag during production. Based on the average feed-to-magnesium ratio (1:6.2) of the Pidgeon process, approximately 6.2 tons of reducing slag are produced for every ton of metallic magnesium produced. Only a small portion of this reducing slag can be recycled; the majority is classified as solid waste. Furthermore, some companies directly dump the reducing slag on wastelands or landfill in hillsides, causing severe dust and soil pollution.

[0003] It is evident that realizing the resource utilization of reduced magnesium slag is crucial for the sustainable development of the Pidgeon process in magnesium smelting under the environmental goals of "dual carbon" (carbon dioxide, carbon dioxide, and carbon emissions). To address these issues, researchers proposed using reduced magnesium slag to replace a portion of cement clinker in the production of slag silicate cement. However, because reduced magnesium slag contains approximately 13% unreduced magnesium oxide, the water absorption of magnesium oxide leads to a sharp decrease in the compressive strength of the cement, resulting in a lower cement grade and failure to meet safety requirements.

[0004] Therefore, traditional technologies still need improvement. Summary of the Invention

[0005] Based on this, one or more embodiments of this application provide a magnesium smelting method, modified magnesium slag, and slag silicate cement. The technical solution includes:

[0006] According to a first aspect of the embodiments of this application, a magnesium smelting method is provided, comprising the following steps:

[0007] Dolomite, fluorite powder, ferrosilicon powder and primary aluminum ash are mixed to obtain a mixture;

[0008] The mixture was subjected to a reduction reaction under vacuum and heating conditions to obtain crude magnesium and reducing slag; and

[0009] Modified magnesium slag was obtained by rapidly cooling the reducing slag with an activating solution.

[0010] In one embodiment, the activation solution includes an activator, which includes one or more of NaHCO3 and (NH4)2HPO4.

[0011] In one embodiment, the concentration of the activator in the activation solution is 1wt% to 14wt%.

[0012] In one embodiment, the main crystalline phase of the modified magnesium slag is β-Ca2SiO3.

[0013] In one embodiment, the method satisfies at least one of the following conditions (1) to (7):

[0014] (1) The content of primary aluminum ash in the mixture is 5wt%~30wt%;

[0015] (2) The alumina content in the primary aluminum ash is 80wt%~85wt%;

[0016] (3) The content of dolomite in the mixture is 56wt%~77wt%;

[0017] (4) The content of ferrosilicon powder in the mixture is 12wt%~16wt%;

[0018] (5) The content of fluorite powder in the mixture is 2wt%~3wt%;

[0019] (6) The temperature of the reduction reaction is 1160℃~1250℃; and

[0020] (7) The vacuum degree of the reduction reaction is 10 Pa to 15 Pa.

[0021] In one embodiment, the rapid cooling method is to use the activation solution to cool the reducing residue by water spraying.

[0022] In one embodiment, after mixing and before the reduction reaction, the following step is included: pressing the mixture to obtain a disc-shaped mixture;

[0023] Optionally, the pressing pressure is 25MPa~30MPa.

[0024] In one embodiment, after rapid cooling, the following steps are also included:

[0025] The modified magnesium slag was subjected to ball milling with rollers and sieved to obtain modified magnesium slag powder.

[0026] Optionally, the mesh size of the sieve used for sieving is 250 to 350 mesh.

[0027] According to a second aspect of the embodiments of this application, a modified magnesium slag is provided, which is prepared by the magnesium smelting method described above.

[0028] According to a third aspect of the embodiments of this application, a slag silicate cement is provided, comprising the above-mentioned modified magnesium slag.

[0029] Compared with traditional technologies, this application has the following advantages:

[0030] In the magnesium smelting method of this application, primary aluminum ash, dolomite, fluorite powder and ferrosilicon powder are mixed as raw materials. The interaction of these substances can improve the magnesium reduction yield and reduce the magnesium oxide content in the reduction slag, thereby reducing the influence of magnesium oxide on the activity of the reduction slag. At the same time, the magnesium slag is rapidly cooled using an activation solution, which converts the calcium silicate in the magnesium slag into β-Ca2SiO3 with gel properties, thereby improving the activity of the modified magnesium slag.

[0031] In addition, the volume expansion of the reducing slag after rapid cooling causes the pellets to crack and pulverize, accelerating the phase transformation of dicalcium silicate, thereby increasing the content of β-dicalcium silicate in the magnesium slag and further improving the activity of the modified magnesium slag. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0033] Figure 1 Image A is an electron micrograph of modified magnesium slag without activator treatment; Figure 1 Image B is an electron microscope image of the modified magnesium slag after treatment with an activator;

[0034] Figure 2 This is a schematic flowchart of a magnesium smelting method according to one embodiment of this application. Detailed Implementation

[0035] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, a detailed description of specific embodiments of this application is provided. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0036] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. Unless otherwise specifically stated, all raw materials, reagents, instruments, and equipment used in this application are commercially available or can be prepared by existing methods.

[0037] In this application, numerical intervals (i.e., numerical ranges) are involved. Unless otherwise specified, the selected numerical distributions within the aforementioned numerical intervals are considered continuous and include the two endpoints (i.e., the minimum and maximum values) of the numerical range, as well as every value between these two endpoints. Unless otherwise specified, when a numerical interval refers only to integers within that interval, it includes the two endpoint integers of the numerical range, as well as every integer between the two endpoints. In this document, this is equivalent to directly listing every integer. For example, if t is an integer selected from 1 to 10, it means that t is any integer selected from the group of integers consisting of 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10. Furthermore, when multiple ranges are provided to describe features or characteristics, these ranges can be merged. In other words, unless otherwise specified, the ranges disclosed herein should be understood to include any and all subranges to which they are included.

[0038] In this application, %(w / w) and wt% both represent weight percentage, %(v / v) refers to volume percentage, and %(w / v) refers to mass-volume percentage.

[0039] Some embodiments of this application provide a magnesium smelting method, including steps S10 to S30.

[0040] Step S10: Mix dolomite, fluorite powder, ferrosilicon powder and primary aluminum ash to obtain a mixture;

[0041] Step S20: The mixture is subjected to a reduction reaction under vacuum and heating conditions to obtain crude magnesium and reducing slag;

[0042] Step S30: The reducing slag is rapidly cooled using an activation solution to obtain modified magnesium slag.

[0043] In some embodiments, in step S10, the content of primary aluminum ash in the mixture is 5wt% to 30wt%.

[0044] In this application, the content of primary aluminum ash in the mixture is "5wt%~30wt%", which can be the minimum and maximum value of the range of 5wt%~30wt%, as well as every value between the minimum and maximum value. Specifically, it includes, but is not limited to, the point values ​​in the embodiments and the following point values: 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, 10wt%, 11wt%, 12wt%, 13wt%, 14wt%, 15wt%, 16wt%, 17wt%, 18wt%, 19wt%, 20wt%, 21wt%, 22wt%, 23wt%, 24wt%, 25wt%, 26wt%, 27wt%, 28wt%, 29wt%, or 30wt%; or any range consisting of any two of these values, such as 10wt%~18wt%.

[0045] In some specific embodiments, the content of primary aluminum ash in the mixture is 14wt% to 30wt%; optionally, the content of primary aluminum ash in the mixture is 20wt% to 30wt%. Understandably, when the content of primary aluminum ash in the mixture reaches more than 30%, the effect on enhancing the strength of cement is not obvious, and it may affect the magnesium yield during the reduction process; therefore, this application controls the content of primary aluminum ash to be below 30wt%.

[0046] In some embodiments, in step S10, the aluminum oxide content in the primary aluminum ash is 80wt%~85wt%.

[0047] In this application, the alumina content in the primary aluminum ash is "80wt%~85wt%", which can be the minimum and maximum value within the range of 5wt%~30wt%, as well as every value between this minimum and maximum value. Specifically, it includes, but is not limited to, the point values ​​in the embodiments and the following point values: 80wt%, 80.1wt%, 80.2wt%, 80.3wt%, 80.4wt%, 80.5wt%, 80.6wt%, 80.7wt%, 80.8wt%, 80.9wt%, 81wt%, 82wt%, 83wt%, 84wt%, or 85wt%; or any range consisting of any two of these values, such as: 81.5wt%~83.6wt%.

[0048] In this application, primary aluminum ash can be the primary aluminum ash produced during the electrolytic aluminum alloying process, and its main component is alumina. Using primary aluminum ash as an additive in the production of metallic magnesium not only improves the strength and activity of the reducing slag, but also increases the utilization rate and added value of primary aluminum ash in the electrolytic aluminum production process; and achieves the organic integration of the aluminum and magnesium industries. In some other embodiments, other substances whose main component is alumina can also be used to replace primary aluminum ash.

[0049] Understandably, this application mixes primary aluminum ash with the raw materials of the traditional Pidgeon process in a specific mass ratio. Since the energy required for aluminum to reduce dolomite is relatively low, the reduction efficiency of magnesium smelting in the Pidgeon process can be improved.

[0050] In some embodiments, in step S10, the dolomite content in the mixture is 56 wt% to 77 wt%. Optionally, the dolomite content is 56 wt% to 69 wt%; more preferably, the dolomite content is 56 wt%.

[0051] In some embodiments, in step S10, the content of ferrosilicon powder in the mixture is 12wt% to 16wt%. Optionally, the content of ferrosilicon powder is 12wt% to 15wt%; more preferably, the content of ferrosilicon powder is 12wt%.

[0052] In some embodiments, in step S10, the content of fluorite powder in the mixture is 2wt% to 3wt%. Optionally, the content of fluorite powder is 2wt%.

[0053] In step S20, magnesium vapor formed after magnesium reduction separates from the reducing slag and is deposited on the crystallizer to form crude magnesium.

[0054] In some embodiments, in step S20, the temperature of the reduction reaction is 1160°C to 1250°C. Optionally, the temperature of the reduction reaction is 1160°C to 1200°C; more preferably, the temperature of the reduction reaction is 1160°C.

[0055] In some embodiments, the vacuum degree of the reduction reaction in step S20 is 10 Pa to 15 Pa. Understandably, in this application, the vacuum degree of the reduction reaction is "10 Pa to 15 Pa," which can be the minimum and maximum value of the range 10 Pa to 15 Pa, as well as every value between these two values. Specifically, this includes, but is not limited to, the point values ​​in the embodiments and the following point values: 10 Pa, 10.1 Pa, 10.2 Pa, 10.3 Pa, 10.4 Pa, 10.5 Pa, 10.6 Pa, 10.7 Pa, 10.8 Pa, 10.9 Pa, 11 Pa, 12 Pa, 13 Pa, 14 Pa, or 15 Pa; or a range consisting of any two of these values, such as 11.5 Pa to 14.5 Pa.

[0056] In some embodiments, after step S10 and before step S20, the following step is also included: pressing the mixture to obtain a disc-shaped mixture.

[0057] In some specific embodiments, the pressing pressure is 25MPa to 30MPa; that is, the minimum and maximum values ​​within the range of 25MPa to 30MPa, as well as every value between these minimum and maximum values. Specifically, this includes, but is not limited to, the point values ​​in the embodiments and the following point values: 25MPa, 25.1MPa, 25.2MPa, 25.3MPa, 25.4MPa, 25.5MPa, 25.6MPa, 25.7MPa, 25.8MPa, 25.9MPa, 26MPa, 27MPa, 28MPa, 29MPa, or 30MPa; or any range consisting of any two of these values, such as 26.5MPa to 28.8MPa.

[0058] In some specific embodiments, in step S30, the activator includes one or more of NaHCO3 and (NH4)2HPO4. That is, the activator can be selected from NaHCO3, or from (NH4)2HPO4, or a mixture of the two substances NaHCO3 and (NH4)2HPO4; understandably, this application does not particularly limit the ratio of NaHCO3 and (NH4)2HPO4 in the mixture. As an example, the mass ratio of NaHCO3 to (NH4)2HPO4 can be (0.3~3):1; for example, it can be 0.4:1, 0.5:1, 0.8:1, 1:1, 1:2 or 1:3.

[0059] In some embodiments, in step S30, the concentration of the activator in the activation solution is 1wt% to 14wt%.

[0060] Understandably, in this application, the concentration of the activator is "1wt%~14wt%", which means the minimum and maximum value of the range of 1wt%~14wt%, as well as every value between the minimum and maximum value. Specifically, it includes, but is not limited to, the point values ​​in the examples and the following point values: 1wt%, 1.2wt%, 1.5wt%, 1.8wt%, 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, 10wt%, 11wt%, 12wt%, 13wt%, or 14wt%; or any range consisting of any two of these values, such as 2.5wt%~12.5wt%.

[0061] In this application, adding a specific concentration and type of activator during the rapid cooling step of magnesium slag can further reduce the magnesium oxide content in the slag. The activator reacts with the magnesium slag to form a gelling β-Ca2SiO3 phase, preventing it from transforming into γ-Ca2SiO3 during cooling. Simultaneously, rapid cooling causes the magnesium slag to expand in volume and the pellets to crack and differentiate, accelerating the phase transformation of dicalcium silicate, thereby increasing the β-dicalcium silicate content in the magnesium slag and further enhancing the activity of the reducing slag.

[0062] Rapid cooling of magnesium slag with an aqueous solution containing an activator transforms the spherical structure on the slag surface into a lamellar structure, thereby increasing the surface activity of the modified magnesium slag and enabling its use in the production of slag silicate cement. In some specific examples, Figure 1 Image A is an electron micrograph of modified magnesium slag without activator treatment; Figure 1 Image B is an electron microscope image of the modified magnesium slag after treatment with an activator.

[0063] In some embodiments, in step S30, the rapid cooling method is to use an activation solution to cool the reducing residue by water spraying.

[0064] In some embodiments, the main crystalline phase of the modified magnesium slag is β-Ca₂SiO₃. β-Ca₂SiO₃ has cementing properties and does not transform into γ-Ca₂SiO₃ during rapid cooling.

[0065] In some implementations, step S30 is followed by step S40.

[0066] Step S40: The modified magnesium slag is subjected to a double-roll ball mill and sieved to obtain modified magnesium slag powder.

[0067] In some specific examples, the sieve used is 250-350 mesh; alternatively, the sieve used is 300 mesh. Understandably, sieving can increase the formation of dicalcium β-silicate during the cooling process.

[0068] In some specific examples, the diameter of the modified magnesium slag powder is less than or equal to 55 μm.

[0069] In one example, the magnesium smelting process of this application is as follows: Figure 2 As shown.

[0070] Some other embodiments of this application provide a modified magnesium slag prepared by the above method.

[0071] Other embodiments of this application provide a slag silicate cement comprising the above-described modified magnesium slag.

[0072] The modified magnesium slag prepared by the above method of this application has the advantages of high activity and can be used to prepare slag silicate cement with good compressive strength; in addition, the method of this application realizes the recycling and reuse of resources and reduces environmental pollution.

[0073] Specifically, the modified magnesium slag described above is mixed with cementitious materials, and slag silicate cement is prepared according to conventional methods in the art.

[0074] Slag silicate cement containing the aforementioned modified magnesium slag exhibits high compressive strength and fully complies with national safety requirements for slag silicate cement. Furthermore, it achieves the recycling and resource reuse of reduction waste slag in the magnesium smelting process, aligning with the "dual-carbon" environmental protection goals.

[0075] The present application will be further described below with reference to specific embodiments and comparative examples, but these should not be construed as limiting the scope of protection of the present application. Unless otherwise specified, the raw materials involved in the following specific embodiments are all commercially available, the instruments used are all commercially available, and the processes involved are conventionally selected by those skilled in the art unless otherwise specified.

[0076] Example 1:

[0077] (1) The primary aluminum ash (alumina content of 80wt%) generated during the electrolytic aluminum alloying process is mixed with dolomite, ferrosilicon powder and fluorite powder to obtain a mixture; by mass percentage, the primary aluminum ash is 20 parts, dolomite is 64 parts, ferrosilicon powder is 14 parts and fluorite powder is 2 parts.

[0078] (2) The mixture was reduced at 1160℃ and 13.3Pa for 5 hours to obtain magnesium slag.

[0079] (3) The magnesium slag was rapidly cooled by water spraying with an activator (a mixed solution of NaHCO3 and (NH4)2HPO4 in a mass ratio of 1:1) at a concentration of 5wt% to obtain modified magnesium slag.

[0080] (4) The cooled modified magnesium slag was ball-milled with rollers and then sieved through a 300-mesh sieve to obtain modified magnesium slag powder with a fineness of 55 μm.

[0081] (5) Mix the modified magnesium slag powder with cement admixture to prepare slag silicate cement; test the slag silicate cement according to the national standard GB / T17671, and its 28-day strength standard is grade 33.5.

[0082] Example 2:

[0083] (1) The primary aluminum ash (alumina content of 80wt%) generated during the electrolytic aluminum alloying process is mixed with dolomite, ferrosilicon powder and fluorite powder to obtain a mixture; by mass percentage, the primary aluminum ash is 14 parts, dolomite is 69 parts, ferrosilicon powder is 15 parts and fluorite powder is 2 parts.

[0084] (2) The mixture was reduced at 1160℃ and 13.3Pa for 5 hours to obtain magnesium slag.

[0085] (3) The magnesium slag was rapidly cooled by water spraying with an activator (a mixed solution of NaHCO3 and (NH4)2HPO4 in a mass ratio of 1:1) at a concentration of 5wt% to obtain modified magnesium slag.

[0086] (4) The cooled modified magnesium slag was ball-milled with rollers and then sieved through a 300-mesh sieve to obtain modified magnesium slag powder with a fineness of 55 μm.

[0087] (5) Mix the modified magnesium slag powder with cement admixture to prepare slag silicate cement; test the slag silicate cement according to the national standard GB / T17671, and its 28-day strength standard is grade 32.6.

[0088] Example 3:

[0089] (1) The primary aluminum ash (alumina content of 80wt%) generated during the electrolytic aluminum alloying process is mixed with dolomite, ferrosilicon powder and fluorite powder to obtain a mixture; by mass percentage, the primary aluminum ash is 10 parts, dolomite is 73 parts, ferrosilicon powder is 15 parts and fluorite powder is 2 parts.

[0090] (2) The mixture was reduced at 1160℃ and 13.3Pa for 5 hours to obtain magnesium slag.

[0091] (3) The magnesium slag was rapidly cooled by water spraying with an activator (a mixed solution of NaHCO3 and (NH4)2HPO4 in a mass ratio of 1:1) at a concentration of 5wt% to obtain modified magnesium slag.

[0092] (4) The cooled modified magnesium slag was ball-milled with rollers and then sieved through a 300-mesh sieve to obtain modified magnesium slag powder with a fineness of 55 μm.

[0093] (5) Mix the modified magnesium slag powder with cement admixture to prepare slag silicate cement; test the slag silicate cement according to the national standard GB / T17671, and its 28-day strength standard is grade 29.8.

[0094] Example 4:

[0095] (1) The primary aluminum ash (alumina content of 80wt%) generated during the electrolytic aluminum alloying process is mixed with dolomite, ferrosilicon powder and fluorite powder to obtain a mixture; by mass percentage, the primary aluminum ash is 5 parts, dolomite is 77 parts, ferrosilicon powder is 16 parts and fluorite powder is 2 parts.

[0096] (2) The mixture was reduced at 1160℃ and 13.3Pa for 5 hours to obtain magnesium slag.

[0097] (3) The magnesium slag was rapidly cooled by water spraying with an activator (a mixed solution of NaHCO3 and (NH4)2HPO4 in a mass ratio of 1:1) at a concentration of 5wt% to obtain modified magnesium slag.

[0098] (4) The cooled modified magnesium slag was ball-milled with rollers and then sieved through a 300-mesh sieve to obtain modified magnesium slag powder with a fineness of 55 μm.

[0099] (5) Mix the modified magnesium slag powder with cement admixture to prepare slag silicate cement; test the slag silicate cement according to the national standard GB / T17671, and its 28-day strength standard is grade 28.5.

[0100] Example 5:

[0101] (1) The primary aluminum ash (alumina content of 80wt%) generated during the electrolytic aluminum alloying process is mixed with dolomite, ferrosilicon powder and fluorite powder to obtain a mixture; by mass percentage, the primary aluminum ash is 30 parts, dolomite is 56 parts, ferrosilicon powder is 12 parts and fluorite powder is 2 parts.

[0102] (2) The mixture was reduced at 1160℃ and 13.3Pa for 5 hours to obtain magnesium slag.

[0103] (3) The magnesium slag was rapidly cooled by water spraying with an activator (a mixed solution of NaHCO3 and (NH4)2HPO4 in a mass ratio of 1:1) at a concentration of 5wt% to obtain modified magnesium slag.

[0104] (4) The cooled modified magnesium slag was ball-milled with rollers and then sieved through a 300-mesh sieve to obtain modified magnesium slag powder with a fineness of 55 μm.

[0105] (5) Mix the modified magnesium slag powder with cement admixture to prepare slag silicate cement; test the slag silicate cement according to the national standard GB / T17671, and its 28-day strength standard is grade 34.

[0106] Example 6:

[0107] (1) The primary aluminum ash (alumina content of 80wt%) generated during the electrolytic aluminum alloying process is mixed with dolomite, ferrosilicon powder and fluorite powder to obtain a mixture; by mass percentage, the primary aluminum ash is 20 parts, dolomite is 64 parts, ferrosilicon powder is 14 parts and fluorite powder is 2 parts.

[0108] (2) The mixture was reduced at 1160℃ and 13.3Pa for 5 hours to obtain magnesium slag.

[0109] (3) Use an activator (NaHCO3) with a concentration of 5wt% to rapidly cool the magnesium slag with water to obtain modified magnesium slag.

[0110] (4) The cooled modified magnesium slag was ball-milled with rollers and then sieved through a 300-mesh sieve to obtain modified magnesium slag powder with a fineness of 55 μm.

[0111] (5) Mix the modified magnesium slag powder with cement admixture to prepare slag silicate cement; test the slag silicate cement according to the national standard GB / T17671, and its 28-day strength standard is grade 33.

[0112] Example 7:

[0113] (1) The primary aluminum ash (alumina content of 80wt%) generated during the electrolytic aluminum alloying process is mixed with dolomite, ferrosilicon powder and fluorite powder to obtain a mixture; by mass percentage, the primary aluminum ash is 20 parts, dolomite is 64 parts, ferrosilicon powder is 14 parts and fluorite powder is 2 parts.

[0114] (2) The mixture was reduced at 1160℃ and 13.3Pa for 5 hours to obtain magnesium slag.

[0115] (3) Use an activator ((NH4)2HPO4) with a concentration of 5wt% to rapidly cool the magnesium slag with water to obtain modified magnesium slag.

[0116] (4) The cooled modified magnesium slag was ball-milled with rollers and then sieved through a 300-mesh sieve to obtain modified magnesium slag powder with a fineness of 55 μm.

[0117] (5) Mix the modified magnesium slag powder with cement admixture to prepare slag silicate cement; test the slag silicate cement according to the national standard GB / T17671, and its 28-day strength standard is grade 33.2.

[0118] Comparative Example 1:

[0119] (1) The primary aluminum ash (alumina content of 80wt%) generated during the electrolytic aluminum alloying process is mixed with dolomite, ferrosilicon powder and fluorite powder to obtain a mixture; by mass percentage, the primary aluminum ash is 1 part, dolomite is 79 parts, ferrosilicon powder is 17 parts and fluorite powder is 3 parts.

[0120] (2) The mixture was reduced at 1160℃ and 13.3Pa for 5 hours to obtain magnesium slag.

[0121] (3) The magnesium slag was rapidly cooled by water spraying with an activator (a mixed solution of NaHCO3 and (NH4)2HPO4 in a mass ratio of 1:1) at a concentration of 5wt% to obtain modified magnesium slag.

[0122] (4) The cooled modified magnesium slag was ball-milled with rollers and then sieved through a 300-mesh sieve to obtain modified magnesium slag powder with a fineness of 55 μm.

[0123] (5) Mix the modified magnesium slag powder with cement admixture to prepare slag silicate cement; test the slag silicate cement according to the national standard GB / T17671, and its 28-day strength standard is grade 27.5.

[0124] Comparative Example 2:

[0125] (1) The primary aluminum ash (alumina content of 80wt%) generated during the electrolytic aluminum alloying process is mixed with dolomite, ferrosilicon powder and fluorite powder to obtain a mixture; by mass percentage, the primary aluminum ash is 5 parts, dolomite is 77 parts, ferrosilicon powder is 16 parts and fluorite powder is 2 parts.

[0126] (2) The mixture was reduced at 1160℃ and 13.3Pa for 5 hours to obtain magnesium slag.

[0127] (3) Use an aqueous solution to rapidly cool the magnesium slag by sprinkling water to obtain modified magnesium slag.

[0128] (4) The cooled modified magnesium slag was ball-milled with rollers and then sieved through a 300-mesh sieve to obtain modified magnesium slag powder with a fineness of 55 μm.

[0129] (5) Mix the modified magnesium slag powder with cement admixture to prepare slag silicate cement; test the slag silicate cement according to the national standard GB / T17671, and its 28-day strength standard is grade 25.

[0130] Table 1 shows the mass percentage of the mixtures in Examples 1-5 and Comparative Examples 1-2, the concentration and type of activator, and the 28-day strength standard of the slag silicate cement finally prepared.

[0131] Table 1

[0132]

[0133] Compared with Example 4, the mass percentage of magnesium smelting raw materials in Comparative Example 1 is different, with primary aluminum ash accounting for only 1%; the 28-day strength standard of the slag silicate cement finally obtained is only grade 27.5.

[0134] Compared with Example 4, the only difference in Comparative Example 2 is that no activator was used for rinsing and cooling, and the 28-day strength standard of the slag silicate cement obtained was only grade 25.

[0135] In summary, the method of this application adds a specific mass percentage of primary aluminum ash to the magnesium smelting raw materials, enabling the modified magnesium slag produced in the Pidgeon process to be used as a raw material for cement preparation, producing slag silicate cement with good compressive strength. This method achieves resource recycling and reuse of reduced magnesium slag, providing a new approach for the "dual-carbon" environmentally friendly development of the Pidgeon process.

[0136] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0137] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A method for smelting magnesium, characterized in that, Includes the following steps: Dolomite, fluorite powder, ferrosilicon powder and primary aluminum ash are mixed to obtain a mixture; The mixture was subjected to a reduction reaction under vacuum and heating conditions to obtain crude magnesium and reducing slag. and Modified magnesium slag was obtained by rapidly cooling the reducing slag with an activating solution.

2. The magnesium smelting method according to claim 1, characterized in that, The activation solution includes an activator, which includes one or more of NaHCO3 and (NH4)2HPO4.

3. The magnesium smelting method according to claim 2, characterized in that, The concentration of the activator in the activation solution is 1wt% to 14wt%.

4. The magnesium smelting method according to claim 1, characterized in that, The main crystalline phase of the modified magnesium slag is β-Ca2SiO3.

5. The magnesium smelting method according to any one of claims 1 to 4, characterized in that, The method satisfies at least one of the following conditions (1) to (7): (1) The content of primary aluminum ash in the mixture is 5wt%~30wt%; (2) The alumina content in the primary aluminum ash is 80wt%~85wt%; (3) The content of dolomite in the mixture is 56wt%~77wt%; (4) The content of ferrosilicon powder in the mixture is 12wt%~16wt%; (5) The content of fluorite powder in the mixture is 2wt%~3wt%; (6) The temperature of the reduction reaction is 1160℃~1250℃; and (7) The vacuum degree of the reduction reaction is 10 Pa to 15 Pa.

6. The magnesium smelting method according to any one of claims 1 to 4, characterized in that, The rapid cooling method involves cooling the reducing residue with water using the activation solution.

7. The magnesium smelting method according to any one of claims 1 to 4, characterized in that, After mixing and before the reduction reaction, the following steps are also included: pressing the mixture to obtain a disc-shaped mixture; Optionally, the pressing pressure is 25MPa~30MPa.

8. The magnesium smelting method according to any one of claims 1 to 4, characterized in that, After rapid cooling, the following steps are also included: The modified magnesium slag was subjected to ball milling with rollers and sieved to obtain modified magnesium slag powder. Optionally, the mesh size of the sieve used for sieving is 250 to 350 mesh.

9. A modified magnesium slag, characterized in that, It is prepared by the magnesium smelting method according to any one of claims 1 to 8.

10. A type of slag silicate cement, characterized in that, Includes the modified magnesium slag as described in claim 9.

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