Method for preparing light-burned magnesia from magnesite flotation tailings

Abstract

The present application relates to the technical field of mineral processing, and particularly relates to a method for preparing light-burned magnesia from magnesite flotation tailings, which comprises the following steps: S1: collecting magnesite flotation tailings and performing grading screening; S2: separating high-purity magnesium-containing tailings from the screened magnesite flotation tailings; S3: grinding the separated magnesium-containing tailings to a nanoscale particle size; S4: removing harmful impurities in the tailings by ion exchange technology; S5: performing drying treatment by using microwave drying technology; S6: performing surface modification treatment on the dried tailings by using plasma technology; S7: performing high-temperature calcination on the modified tailings to prepare light-burned magnesia; and S8: then performing micro-particle separation to obtain products of different particle size specifications. The present application not only significantly improves the resource recovery rate and product quality, but also reduces energy consumption and environmental impact, and has a broad application prospect and significant economic benefits.

Description

Technical Field

[0001] This invention relates to the field of mineral processing technology, and in particular to a method for preparing lightly calcined magnesia from magnesite flotation tailings. Background Technology

[0002] This invention relates to the fields of mineral processing and metallurgical engineering technology, and in particular to a method for preparing lightly calcined magnesia from magnesite flotation tailings. Magnesite is an important magnesium-bearing mineral, widely used in the preparation of various magnesium compounds, such as lightly calcined magnesia and magnesium oxide. In the traditional magnesite processing, a large amount of tailings are usually generated. These tailings are often treated as waste, resulting in resource waste and environmental pollution. However, these tailings still contain a certain proportion of valuable magnesite components. If they can be effectively recycled and utilized, it can not only reduce the environmental burden but also improve the comprehensive utilization rate of resources.

[0003] Currently, the recycling and reuse of magnesite tailings faces multiple technical challenges. First, the magnesite content in the tailings is relatively low, and it is mixed with various impurities, such as iron and aluminum ions, which can affect the quality of the final product. Second, traditional processing methods, such as simple physical crushing and chemical methods, are inefficient, energy-intensive, and difficult to meet environmental protection requirements.

[0004] Therefore, there is an urgent need for an efficient and environmentally friendly technology to extract high-quality lightly calcined magnesia from magnesite tailings. Summary of the Invention

[0005] To achieve the above objectives, the present invention provides a method for preparing lightly calcined magnesia from magnesite flotation tailings.

[0006] A method for preparing lightly calcined magnesia from magnesite flotation tailings includes the following steps:

[0007] S1: Collect magnesite flotation tailings and perform classification and screening to remove large particle impurities;

[0008] S2: High-purity magnesium-containing tailings are separated from the screened magnesite flotation tailings using magnetic separation.

[0009] S3: Apply nano-grinding technology to grind the separated magnesium-containing tailings to nanoscale particle size;

[0010] S4: After grinding, harmful impurities in the tailings are removed by ion exchange technology;

[0011] S5: Microwave drying technology is used to dry the tailings after removing harmful impurities;

[0012] S6: Surface modification treatment of dried tailings using plasma technology;

[0013] S7: In a fluidized bed reactor, the modified tailings are roasted at high temperature to obtain lightly calcined magnesia.

[0014] S8: Lightly calcined magnesia is solidified by rapid cooling technology, and then micro-particle separation is performed to obtain products with different particle size specifications.

[0015] Furthermore, S1 specifically includes:

[0016] S11: Tailings collected from the flotation process of magnesite ore, wherein the initial moisture content of the tailings is controlled at 40-60%.

[0017] S12: Perform preliminary crushing on the collected tailings, and control the particle size of the preliminary crushing to be reduced to within 50 mm;

[0018] S13: The tailings after preliminary crushing are classified by a vibrating screen to screen out medium-sized tailings with a particle size of 5-20 mm.

[0019] S14: Air separation is performed on the screened medium-sized tailings to remove attached soil and light impurities.

[0020] Furthermore, S2 specifically includes:

[0021] S21: Pre-magnetize the tailings obtained after grading and screening to improve the responsiveness of the tailings during the magnetic separation process. The pre-magnetization intensity is between 100-300 amperes / meter.

[0022] S22: During the magnetic separation process, the magnetic field strength of the magnetic separator is set to 0.5-1.5 Tesla to effectively separate magnesium-containing minerals and non-magnetic impurities;

[0023] S23: The pretreated tailings are fed into a magnetic separator for magnetic separation. During the magnetic separation process, the magnetic drum speed is kept at 50-100 rpm.

[0024] S24: The magnesium-containing tailings separated during the magnetic separation process are subjected to secondary screening to remove any particles larger than 5 mm to ensure the uniformity and purity of the resulting tailings.

[0025] Furthermore, S3 specifically includes:

[0026] S31: First, the magnesium-containing tailings that have been separated by magnetic separation are uniformly wetted to a degree of 5-10% of the tailings weight.

[0027] S32: High-hardness zirconia beads are selected as the grinding media, and the diameter of the zirconia beads is 0.5-1.5 mm;

[0028] S33: Place the moist tailings and grinding media into the nano-grinding machine, and set the grinding speed to 2000-5000 rpm, and the grinding time to 1-3 hours;

[0029] S34: After grinding, use a laser particle size analyzer to analyze the particle size of the ground tailings to ensure that the average particle size of the tailings is 50-100 nanometers.

[0030] Furthermore, S4 specifically includes:

[0031] S41: A strong acidic cation exchange resin is selected as the exchange medium, with a specific exchange capacity of 1.5-2.5 mg Equivalents / g, to remove metal ions such as iron and aluminum;

[0032] S42: Mix nano-sized tailings with ion exchange resin at a mass ratio of 1:5 to 1:10;

[0033] S43: Ion exchange treatment is carried out under constant temperature conditions of 25-35 degrees Celsius for 1-3 hours to ensure that the total content of iron and aluminum heavy metal impurities is less than 0.1%.

[0034] Furthermore, S5 specifically includes:

[0035] S51: Spread the tailings that have undergone ion exchange treatment evenly on a microwave drying tray, and control the thickness of the tailings layer to be 2-5 cm to promote uniform drying.

[0036] S52: Set the power of the microwave dryer to 5-15 kilowatts to ensure sufficient energy to penetrate the tailings layer while avoiding overheating. During the microwave drying process, control the drying time to 30-60 minutes.

[0037] S53: Throughout the drying process, the temperature of the tailings shall be controlled to not exceed 100 degrees Celsius to prevent thermal damage to the material;

[0038] S54: After drying, test the moisture content of the tailings to ensure that the moisture content is reduced to below 5%.

[0039] Furthermore, S6 specifically includes:

[0040] S61: Select a plasma treatment device for surface modification and set the operating frequency of the device to 13.56-40.68 MHz;

[0041] S62: Spread the dried tailings evenly in the plasma treatment chamber;

[0042] S63: Set the plasma treatment power to 500-2000 watts and the treatment time to 1-5 minutes;

[0043] S64: During plasma treatment, maintain the atmosphere in the treatment chamber as an inert gas with a gas flow rate of 50-100 ml / min;

[0044] S65: After processing, the tailings should be naturally cooled to ambient temperature at room temperature and then stored in a dry, dark place.

[0045] Furthermore, S7 specifically includes:

[0046] S71: Select a high-temperature calcined fluidized bed reactor with a maximum temperature capacity of not less than 1200 degrees Celsius;

[0047] S72: Distribute the plasma-modified tailings evenly in the fluidized bed reactor to ensure uniform tailings layer thickness;

[0048] S73: Set the calcination temperature of the fluidized bed reactor to 800-950 degrees Celsius and the calcination time to 1-3 hours;

[0049] S74: During the roasting process, adjust the airflow speed to 2-5 m / s;

[0050] S75: After calcination, reduce the temperature in the fluidized bed to allow the lightly calcined magnesia to cool naturally to room temperature.

[0051] Furthermore, S8 specifically includes:

[0052] S81: After the lightly calcined magnesia has been calcined, the rapid cooling system is immediately started to quickly reduce the temperature in the fluidized bed from the calcination temperature to room temperature at a rate of 100-200 degrees Celsius / minute.

[0053] S82: During rapid cooling, cooling water or cooling gas is selected as the cooling medium to effectively reduce the temperature of lightly calcined magnesia quickly.

[0054] S83: The cooled lightly calcined magnesia is fed into a particle size separation device for micro-particle separation. Different screens are set during the separation process to obtain products with different particle size specifications.

[0055] Furthermore, the particle size specifications include less than 50 micrometers, 50-100 micrometers, and greater than 100 micrometers.

[0056] The beneficial effects of this invention are:

[0057] This invention utilizes nano-grinding technology to significantly increase the reaction area of ​​magnesite in tailings, while ion exchange technology effectively removes harmful impurities. These steps together ensure the high purity and excellent quality of the lightly calcined magnesite extracted from tailings. Therefore, this invention not only achieves the effective utilization of tailings but also increases the recovery of valuable resources, playing an important role in promoting the comprehensive utilization of resources and significantly improving the recovery rate of valuable magnesite.

[0058] This invention significantly reduces energy consumption while improving processing efficiency. In particular, by applying microwave drying technology and efficient fluidized bed calcination technology, it not only improves energy utilization efficiency but also reduces energy consumption and emissions. In addition, plasma surface modification technology and rapid cooling technology further optimize the processing and reduce environmental pollution that may be caused by traditional methods. Therefore, this invention not only improves product quality but also reflects a high degree of responsibility for environmental protection.

[0059] The high-quality light-burned magnesia produced by this invention has broad market application prospects. As an important industrial raw material, light-burned magnesia is widely used in many fields such as construction, chemical industry, and metallurgy. Therefore, this invention not only has important industrial application value, but also indicates significant economic benefits and plays a positive role in promoting the development of related industries. Attached Figure Description

[0060] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only for this invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0061] Figure 1 This is a schematic diagram of the process for preparing lightly calcined magnesia according to an embodiment of the present invention. Detailed Implementation

[0062] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0063] It should be noted that, unless otherwise defined, the technical or scientific terms used in this invention should have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0064] Example 1

[0065] like Figure 1 As shown, a method for preparing lightly calcined magnesia from magnesite flotation tailings includes the following steps:

[0066] S1: Collect magnesite flotation tailings and perform classification and screening to remove large particle impurities;

[0067] S2: High-purity magnesium-containing tailings are separated from the screened magnesite flotation tailings using magnetic separation.

[0068] S3: Apply nano-grinding technology to grind the separated magnesium-containing tailings to nanoscale particle size in order to increase the reaction area;

[0069] S4: After grinding, harmful impurities such as iron and aluminum metal ions are removed from the tailings through ion exchange technology;

[0070] S5: Microwave drying technology is used to dry the tailings after removing harmful impurities;

[0071] S6: Surface modification of dried tailings using plasma technology to enhance their affinity with reactants;

[0072] S7: In a fluidized bed reactor, the modified tailings are roasted at high temperature to produce lightly calcined magnesia. This process improves energy efficiency and reduces emissions.

[0073] S8: Lightly calcined magnesia is solidified by rapid cooling technology, and then micro-particle separation is performed to obtain products with different particle size specifications.

[0074] S1 specifically includes:

[0075] S11: Tailings collected from the flotation process of magnesite ore, wherein the initial moisture content of the tailings is controlled at 50% to ensure the effectiveness of subsequent processing.

[0076] S12: Perform preliminary crushing on the collected tailings, controlling the particle size of the preliminary crushing to be reduced to within 50 mm, in order to facilitate subsequent screening.

[0077] S13: The tailings after preliminary crushing are classified by a vibrating screen to screen out medium-sized tailings with a particle size of 13 mm for subsequent magnetic separation. The fine tailings smaller than 5 mm produced during screening can be stored separately for possible further utilization or processing.

[0078] S14: Air separation is performed on the screened medium-sized tailings to remove attached soil and light impurities, ensuring the purity and quality of the tailings.

[0079] S2 specifically includes:

[0080] S21: The tailings obtained after grading and screening are pre-magnetized to improve the responsiveness of the tailings during the magnetic separation process. The pre-magnetization intensity is between 200 amperes / meter.

[0081] S22: During the magnetic separation process, the magnetic field strength of the magnetic separator is set to 1.0 Tesla to effectively separate magnesium-containing minerals and non-magnetic impurities;

[0082] S23: The pretreated tailings are fed into a magnetic separator for magnetic separation. During the magnetic separation process, the magnetic drum speed is kept at 70 rpm to ensure effective separation of magnetic materials.

[0083] S24: The magnesium-containing tailings separated during the magnetic separation process are subjected to secondary screening to remove any particles larger than 5 mm to ensure the uniformity and purity of the resulting tailings.

[0084] S3 specifically includes:

[0085] S31: First, the magnesium-containing tailings that have been separated by magnetic separation are uniformly wetted to a degree of 7% of the tailings weight.

[0086] S32: High-hardness zirconia beads are selected as the grinding media. The diameter of the zirconia beads is 1 mm, in order to improve grinding efficiency and achieve the goal of nanoscale particle size.

[0087] S33: Place the moist tailings and grinding media into a nano-grinding mill, set the mill speed to 3500 rpm, and the grinding time to 2 hours to ensure that the tailings particle size reaches the nanoscale.

[0088] S34: After grinding, use a laser particle size analyzer to analyze the particle size of the ground tailings to ensure that the average particle size of the tailings is 80 nanometers.

[0089] S4 specifically includes:

[0090] S41: A strong acidic cation exchange resin is selected as the exchange medium, with a specific exchange capacity of 2.0 mg Equivalents / g, to remove metal ions such as iron and aluminum;

[0091] S42: Nanoscale tailings are mixed with ion exchange resin at a mass ratio of 1:7 to ensure sufficient contact and impurity adsorption.

[0092] S43: Ion exchange treatment is carried out at a constant temperature of 30 degrees Celsius for 2 hours to ensure effective removal of harmful impurities from the tailings and to ensure that the total content of iron and aluminum heavy metal impurities is less than 0.1%. After the ion exchange is completed, the treated tailings are rinsed with deionized water to remove residual ion exchange resin and exchanged impurities.

[0093] S5 specifically includes:

[0094] S51: Spread the tailings that have undergone ion exchange treatment evenly on a microwave drying tray, and control the thickness of the tailings layer to 3 cm to promote uniform drying.

[0095] S52: Set the power of the microwave dryer to 10 kilowatts to ensure sufficient energy to penetrate the tailings layer while avoiding overheating. During the microwave drying process, control the drying time to 45 minutes.

[0096] S53: Throughout the drying process, the temperature of the tailings shall be controlled to not exceed 100 degrees Celsius to prevent thermal damage to the material;

[0097] S54: After drying, test the moisture content of the tailings to ensure that the moisture content is reduced to 2% to meet the requirements of subsequent processing steps.

[0098] S6 specifically includes:

[0099] S61: Select a plasma treatment device for surface modification and set the operating frequency of the device to 30 MHz;

[0100] S62: Spread the dried tailings evenly in the plasma treatment chamber to ensure that the amount of tailings processed in each batch matches the capacity of the treatment chamber, so as to ensure the uniformity of the processing.

[0101] S63: Set the plasma treatment power to 1300 watts and the treatment time to 4 minutes to achieve effective surface modification.

[0102] S64: During plasma treatment, the atmosphere in the treatment chamber is maintained as an inert gas with a gas flow rate of 70 ml / min to prevent material oxidation and enhance the treatment effect. After plasma treatment, the surface energy tester is used to detect the modification effect on the tailings surface to ensure that its contact angle increases significantly, indicating an improvement in surface hydrophilicity or oleophilicity.

[0103] S65: The processed tailings are naturally cooled to ambient temperature at room temperature and then stored in a dry, dark place to maintain the stability of the modification effect.

[0104] S7 specifically includes:

[0105] S71: Select a high-temperature calcined fluidized bed reactor with a maximum temperature capacity of not less than 1200 degrees Celsius;

[0106] S72: The plasma-modified tailings are evenly distributed in the fluidized bed reactor to ensure that the tailings layer has a uniform thickness, so as to promote uniform heat transfer.

[0107] S73: Set the roasting temperature of the fluidized bed reactor to 870 degrees Celsius and the roasting time to 2 hours to ensure that the tailings are fully decomposed and form lightly calcined magnesia.

[0108] S74: During the roasting process, the airflow velocity is adjusted to 4 m / s to ensure uniform flow of tailings and uniform heat distribution within the fluidized bed.

[0109] S75: After calcination, reduce the temperature in the fluidized bed to allow the lightly calcined magnesia to cool naturally to room temperature in order to avoid structural damage caused by rapid temperature changes.

[0110] S8 specifically includes:

[0111] S81: After the lightly calcined magnesia has been calcined, the rapid cooling system is immediately started to quickly reduce the temperature in the fluidized bed from the calcination temperature to room temperature at a rate of 150 degrees Celsius / minute.

[0112] S82: During the rapid cooling process, cooling water is selected as the cooling medium to effectively reduce the temperature of the lightly calcined magnesia quickly while maintaining the structural integrity of the material.

[0113] S83: The cooled lightly calcined magnesia is fed into a particle size separation device for micro-particle separation. Different screens are set during the separation process to obtain products with different particle size specifications.

[0114] Particle size specifications include less than 50 micrometers, 50-100 micrometers and greater than 100 micrometers.

[0115] Example 2

[0116] S1: First, collect tailings from the flotation process of magnesite ore, keep the initial moisture content at 40%, and perform preliminary crushing on the collected tailings to control the particle size after crushing to within 50 mm. Then, classify the tailings by vibrating screen, screen out medium-sized tailings with a particle size of 5 mm, and perform air separation to remove attached soil and light impurities.

[0117] S2: Magnetic separation treatment. The tailings after grading and screening are pre-magnetized to enhance their responsiveness in the magnetic separation process. The pre-magnetization intensity is 100 amperes / meter. Subsequently, the magnetic field strength is set to 0.5 Tesla in the magnetic separator for magnetic separation, while the magnetic drum speed is kept at 50 revolutions / minute. After magnetic separation, the magnesium-containing tailings are subjected to secondary screening to remove any particles larger than 5 mm.

[0118] S3: First, the magnesium-containing tailings separated by magnetic separation are uniformly moistened to a degree of 5% of the tailings weight. Zirconia beads with a diameter of 0.5 mm are selected as grinding media. The moistened tailings and grinding media are put into a nano-grinding machine. The grinding speed is set to 2000 rpm and the grinding time is 1 hour. After completion, a laser particle size analyzer is used to ensure that the average particle size of the tailings is 50 nanometers.

[0119] S4: Ion exchange for impurity removal. Strong acidic cation exchange resin is used for ion exchange treatment with a specific exchange capacity of 1.5 mg Equivalent / g. Nanoscale tailings are mixed with resin at a mass ratio of 1:5 and treated at a constant temperature of 25 degrees Celsius for 1 hour to remove heavy metal impurities such as iron and aluminum, ensuring that their total content is less than 0.1%.

[0120] S5: Spread the tailings after ion exchange treatment evenly on the microwave drying tray, control the tailings layer thickness to 2 cm, set the power of the microwave dryer to 5 kW, control the drying time to 30 minutes, and ensure that the temperature of the tailings does not exceed 100 degrees Celsius to prevent heat damage. After drying, test the moisture content to ensure it drops to 4%.

[0121] S6: The surface modification treatment of tailings is carried out using plasma technology. The working frequency of the plasma treatment equipment is set to 13.56 MHz, the power is 500 watts, and the treatment time is 1 minute. During the treatment, the atmosphere in the treatment chamber is kept as an inert gas with a flow rate of 50 ml / min. After the treatment is completed, the tailings are allowed to cool naturally at room temperature.

[0122] S7: Distribute the plasma-modified tailings evenly in the reactor to ensure the uniform thickness of the tailings layer. Set the roasting temperature to 800 degrees Celsius and the time to 1 hour. During the roasting process, adjust the airflow speed to 2 m / s.

[0123] S8: After calcination is completed, the rapid cooling system is immediately started to quickly reduce the temperature from the calcination temperature to room temperature at a rate of 100 degrees Celsius per minute. Cooling gas is used as the cooling medium. The cooled calcined magnesia is then sent to a particle size separation device, where different screens are used to separate the particles into different sizes.

[0124] Example 3

[0125] S1: First, collect tailings from the flotation process of magnesite ore, keep the initial moisture content at 60%, and perform preliminary crushing on the collected tailings to control the particle size after crushing to within 50 mm. Then, classify the tailings by vibrating screen to screen out medium-sized tailings with a particle size of 20 mm, and perform air separation to remove attached soil and light impurities.

[0126] S2: Magnetic separation treatment. The tailings after grading and screening are pre-magnetized to enhance their responsiveness in the magnetic separation process. The pre-magnetization intensity is 300 amperes / meter. Subsequently, the magnetic separation is carried out in the magnetic separator with a magnetic field strength of 1.5 Tesla, while maintaining the magnetic drum speed at 100 revolutions / minute. After magnetic separation, the magnesium-containing tailings are subjected to secondary screening to remove any particles larger than 5 mm.

[0127] S3: First, the magnesium-containing tailings separated by magnetic separation are uniformly moistened to a degree of 10% of the tailings weight. Zirconia beads with a diameter of 1.5 mm are selected as grinding media. The moistened tailings and grinding media are put into a nano-grinding machine. The grinding machine speed is set to 5000 rpm and the grinding time is 3 hours. After completion, a laser particle size analyzer is used to ensure that the average particle size of the tailings is 100 nanometers.

[0128] S4: Ion exchange for impurity removal. Strong acidic cation exchange resin is used for ion exchange treatment. Its specific exchange capacity is 2.5 mg Equivalent / g. The nano-sized tailings are mixed with the resin at a mass ratio of 1:10 and treated at a constant temperature of 35 degrees Celsius for 3 hours to remove heavy metal impurities such as iron and aluminum, ensuring that their total content is less than 0.1%.

[0129] S5: Spread the tailings after ion exchange treatment evenly on the microwave drying tray, control the tailings layer thickness to 5 cm, set the power of the microwave dryer to 15 kW, control the drying time to 60 minutes, and ensure that the temperature of the tailings does not exceed 100 degrees Celsius to prevent heat damage. After drying, test the moisture content to ensure that it drops to 5%.

[0130] S6: The surface modification treatment of tailings is carried out using plasma technology. The working frequency of the plasma treatment equipment is set to 40.68 MHz, the power is 2000 watts, and the treatment time is 5 minutes. During the treatment, the atmosphere in the treatment chamber is kept as an inert gas with a flow rate of 100 ml / min. After the treatment is completed, the tailings are allowed to cool naturally at room temperature.

[0131] S7: Distribute the plasma-modified tailings evenly in the reactor to ensure the uniform thickness of the tailings layer. Set the roasting temperature to 950 degrees Celsius and the time to 3 hours. During the roasting process, adjust the airflow speed to 5 m / s.

[0132] S8: After calcination is completed, the rapid cooling system is immediately started to quickly reduce the temperature from the calcination temperature to room temperature at a rate of 200 degrees Celsius per minute. Cooling water is used as the cooling medium. The cooled calcined magnesia is then sent to a particle size separation device, where different screens are used to separate the particles into different sizes.

[0133] Table 1 Comparison of Finished Product Performance Parameters

[0134] Average particle size (nanometers) 80 50 100 Magnesium content (%) 92.5 89.7 90.3 Impurity content (%) 0.08 0.1 0.09 <![CDATA[Specific surface area (m 2 / g)]]> 120 140 110 Thermal stability (%) 95 92 93 Moisture content (%) 2 4 5 Crystallinity (%) 85 80 82

[0135] As can be seen from Table 1 above, the average particle size of Example 1 is 80 nanometers, which, compared to 50 nanometers in Example 2 and 100 nanometers in Example 3, shows a more uniform particle size distribution. Smaller particle size helps increase the specific surface area but also reduces thermal stability. Example 1 has the highest magnesium content, reaching 92.5%, while the impurity content is controlled at 0.08%, indicating high purity. This is due to the use of more suitable magnetic separation and ion exchange conditions, which effectively removed more impurities. Example 1 has a high specific surface area (120 m²). 2 The high moisture content (2%) and thermal stability (95%) of Example 1 indicate that its structure is more compact and stable, making it suitable for high-temperature applications. The low moisture content (2%) and high crystallinity (85%) of Example 1 indicate that its drying and calcination processes were properly controlled, which helps to maintain good physical properties.

[0136] In summary, Example 1 exhibits the best performance in terms of particle size control, magnesium content, impurity content, specific surface area, thermal stability, moisture content, and crystallinity. These factors work together to make it the best example, and these characteristics give lightly calcined magnesia significant advantages in terms of high temperature, high purity, and specific application performance.

[0137] This invention is intended to cover all such substitutions, modifications, and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A method for preparing lightly calcined magnesia from magnesite flotation tailings, characterized in that, Includes the following steps: S1: Collect magnesite flotation tailings and perform classification and screening to remove large particle impurities; S2: High-purity magnesium-containing tailings are separated from the screened magnesite flotation tailings using magnetic separation. S3: Apply nano-grinding technology to grind the separated magnesium-containing tailings to nanoscale particle size; S3 specifically includes: S31: First, the magnesium-containing tailings that have undergone magnetic separation are uniformly wetted to a degree of 5-10% of the tailings weight; S32: High-hardness zirconia beads are selected as the grinding media, and the diameter of the zirconia beads is 0.5-1.5 mm; S33: Place the moist tailings and grinding media into the nano-grinding machine, and set the grinding speed to 2000-5000 rpm, and the grinding time to 1-3 hours; S34: After grinding, use a laser particle size analyzer to analyze the particle size of the ground tailings to ensure that the average particle size of the tailings is 50-100 nanometers. S4: After grinding, harmful impurities in the tailings are removed by ion exchange technology; S4 specifically includes: S41: A strong acidic cation exchange resin is selected as the exchange medium, with a specific exchange capacity of 1.5-2.5 mg Equivalents / g, to remove iron and aluminum metal ions; S42: Mix nano-sized tailings with ion exchange resin at a mass ratio of 1:5 to 1:10; S43: Ion exchange treatment is carried out under constant temperature conditions of 25-35 degrees Celsius for 1-3 hours to ensure that the total content of iron and aluminum heavy metal impurities is less than 0.1%; S5: Microwave drying technology is used to dry the tailings after removing harmful impurities; S6: Surface modification treatment of dried tailings using plasma technology; S6 specifically includes: S61: Select a plasma treatment device for surface modification and set the operating frequency of the device to 13.56-40.68 MHz; S62: Spread the dried tailings evenly in the plasma treatment chamber; S63: Set the plasma treatment power to 500-2000 watts and the treatment time to 1-5 minutes; S64: During plasma treatment, maintain the atmosphere in the treatment chamber as an inert gas with a gas flow rate of 50-100 ml / min; S65: Allow the processed tailings to cool naturally to ambient temperature at room temperature, and then store them in a dry, dark place. S7: In a fluidized bed reactor, the modified tailings are roasted at high temperature to produce lightly calcined magnesia. The maximum temperature capacity of the reactor is not less than 1200 degrees Celsius. The roasting temperature of the fluidized bed reactor is set to 800-950 degrees Celsius, and the roasting time is 1-3 hours. During the roasting process, the airflow velocity is adjusted to 2-5 m / s. S8: Lightly calcined magnesia is solidified by rapid cooling technology, and then micro-particle separation is performed to obtain products with different particle size specifications.

2. The method for preparing lightly calcined magnesia from magnesite flotation tailings according to claim 1, characterized in that, S1 specifically includes: S11: Tailings collected from the flotation process of magnesite ore, wherein the initial moisture content of the tailings is controlled at 40-60%; S12: Perform preliminary crushing on the collected tailings, and control the particle size of the preliminary crushing to be reduced to within 50 mm; S13: The tailings after preliminary crushing are classified by a vibrating screen to screen out medium-sized tailings with a particle size of 5-20 mm. S14: Air separation is performed on the screened medium-sized tailings to remove attached soil and light impurities.

3. The method for preparing lightly calcined magnesite from magnesite flotation tailings according to claim 2, characterized in that, S2 specifically includes: S21: Pre-magnetize the tailings obtained after grading and screening to improve the responsiveness of the tailings during the magnetic separation process. The pre-magnetization intensity is between 100-300 amperes / meter. S22: During the magnetic separation process, the magnetic field strength of the magnetic separator is set to 0.5-1.5 Tesla to effectively separate magnesium-containing minerals and non-magnetic impurities; S23: The pretreated tailings are fed into a magnetic separator for magnetic separation. During the magnetic separation process, the magnetic drum speed is kept at 50-100 rpm. S24: The magnesium-containing tailings separated during the magnetic separation process are subjected to secondary screening to remove any particles larger than 5 mm to ensure the uniformity and purity of the resulting tailings.

4. The method for preparing lightly calcined magnesite from magnesite flotation tailings according to claim 3, characterized in that, S5 specifically includes: S51: Spread the tailings that have undergone ion exchange treatment evenly on a microwave drying tray, and control the thickness of the tailings layer to be 2-5 cm to promote uniform drying. S52: Set the power of the microwave dryer to 5-15 kilowatts to ensure sufficient energy to penetrate the tailings layer while avoiding overheating. During the microwave drying process, control the drying time to 30-60 minutes. S53: Throughout the drying process, the temperature of the tailings shall be controlled to not exceed 100 degrees Celsius to prevent thermal damage to the material; S54: After drying, test the moisture content of the tailings to ensure that the moisture content is reduced to below 5%.

5. The method for preparing lightly calcined magnesite from magnesite flotation tailings according to claim 4, characterized in that, S8 specifically includes: S81: After the lightly calcined magnesia has been calcined, the rapid cooling system is immediately started to quickly reduce the temperature in the fluidized bed from the calcination temperature to room temperature at a rate of 100-200 degrees Celsius / minute. S82: During rapid cooling, cooling water or cooling gas is selected as the cooling medium to effectively reduce the temperature of lightly calcined magnesia quickly. S83: The cooled lightly calcined magnesia is fed into a particle size separation device for micro-particle separation. Different screens are set during the separation process to obtain products with different particle size specifications.

6. The method for preparing lightly calcined magnesite from magnesite flotation tailings according to claim 5, characterized in that, The particle size specifications include less than 50 micrometers, 50-100 micrometers, and greater than 100 micrometers.

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