A 414-type basic magnesium carbonate and a method for producing the same

Abstract

The application provides a 414 type basic magnesium carbonate and a preparation method thereof. The preparation method comprises the following steps: adding ammonia water into a magnesium sulfate solution, removing impurities by adjusting the pH value, filtering and diluting or concentrating the suspension after the impurities are removed to obtain a refined magnesium sulfate solution; injecting ammonia water and CO2 into the refined magnesium sulfate solution, stirring and heating to obtain a suspension I; cooling and aging the suspension I to obtain a suspension II; filtering the suspension II to obtain a filtrate and a filter residue, and drying and dispersing the filter residue to obtain the 414 type basic magnesium carbonate. The 414 type basic magnesium carbonate is prepared by the preparation method of the 414 type basic magnesium carbonate, and the crystal morphology of the 414 type basic magnesium carbonate is spherical and / or corolla-shaped. The preparation method is simple, the product morphology is controllable, and the product has high purity. The 414 type basic magnesium carbonate has complete morphology and uniform size.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of inorganic material preparation, in particular, to a 414 type basic magnesium carbonate and a preparation method thereof. BACKGROUND

[0002] The basic magnesium carbonate is an important inorganic mineral material, which can exist stably under natural environmental conditions, and can be used as an excellent reinforcing agent and filler for high molecular polymers such as rubber and plastic, and for an automobile safety airbag gas generating agent. Moreover, the basic magnesium carbonate has the characteristics of high temperature resistance, non-combustion, light texture and loose, so it is not only a green environmental protection flame retardant, but also an important intermediate raw material for preparing other fine magnesium salts. In the existing preparation methods of the basic magnesium carbonate, there are often the problems of complex process and difficult morphology control. Therefore, in order to solve the above-mentioned defects and technical problems in the existing preparation method of the basic magnesium carbonate, the present application provides a preparation method for preparing the 414 type basic magnesium carbonate by a one-step method of a magnesium sulfate solution and the 414 type basic magnesium carbonate.

[0003] The Chinese invention patent with the application number of "CN202110704657.6" and the name of "Flower petal-shaped large pore structure hydrotalcite material and its preparation method and application, mixed metal oxide and its preparation method" discloses a preparation method of a flower petal-shaped large pore structure hydrotalcite material, which comprises the steps of: mixing a magnesium-containing dispersion liquid, a carbonate / hydrogen carbonate solution and a template agent, carrying out a first hydrothermal synthesis reaction on the obtained mixed liquid to obtain a flower petal-shaped basic magnesium carbonate; the carbonate / hydrogen carbonate solution is a carbonate solution or a hydrogen carbonate solution; mixing the flower petal-shaped basic magnesium carbonate, water and sodium metaaluminate to carry out a second hydrothermal synthesis reaction to obtain the flower petal-shaped large pore structure hydrotalcite material. The prepared hydrotalcite material can be used to prepare a mixed metal oxide for FCC flue gas desulfurization after high temperature calcination, and has a good desulfurization effect in the FCC flue gas desulfurization. However, the preparation method is different from the present application, and the energy consumption required by the hydrothermal reaction in the process is high.

[0004] A Chinese invention patent with the application number "CN202110381838.X" and the title "Method for producing ammonium magnesium sulfate and basic magnesium carbonate based on boron mud" discloses a method for producing basic magnesium carbonate based on boron mud. The method uses boron mud, a waste residue after the production of borax, as the raw material, adds ammonium bisulfate, heats to 20-100°C, stirs for 10-60 minutes, and performs solid-liquid separation on the obtained suspension to obtain an ammonium magnesium sulfate solution. Then, the ammonium magnesium sulfate solution is used as the raw material to add ammonium carbonate and stir at 20-60°C for 20-80 minutes to prepare basic magnesium carbonate. The use of ammonium bisulfate and ammonium carbonate raw materials has low requirements for equipment, solves the problems of equipment corrosion by strong acid and impurity removal, and reduces production costs while improving safety. However, the preparation method is different from the present application, and the process cannot control the morphology of the product. SUMMARY

[0005] The present application aims to solve at least one of the above-mentioned deficiencies in the prior art. For example, one of the objectives of the present application is to provide a method for preparing 414-type basic magnesium carbonate with simple process, controllable product morphology, and high product purity. For another example, another objective of the present application is to provide 414-type basic magnesium carbonate with complete morphology and uniform size.

[0006] To achieve the above-mentioned objectives, one aspect of the present application provides a method for preparing 414-type basic magnesium carbonate. The method can include: adding ammonia water to a magnesium sulfate solution, adjusting the pH value for impurity removal, filtering and diluting or concentrating the suspension after impurity removal to obtain a refined magnesium sulfate solution; injecting ammonia water and CO2 into the refined magnesium sulfate solution, stirring and heating to obtain a suspension I; cooling and aging the suspension I to obtain a suspension II; filtering the suspension II to obtain a filtrate and a filter residue, and treating the filter residue by drying and dispersing to obtain 414-type basic magnesium carbonate.

[0007] According to one or more exemplary embodiments of one aspect of the present application, the concentration of ammonia water added to the magnesium sulfate solution can be 3 mol / L-5 mol / L, and the concentration of ammonia water injected into the refined magnesium sulfate solution can be 1 mol / L-3 mol / L.

[0008] According to one or more exemplary embodiments of one aspect of the present application, the ratio of the injection rate of ammonia water to CO2 into the refined magnesium sulfate solution can be 1-4:1 in terms of molar ratio.

[0009] According to one or more exemplary embodiments of one aspect of the present application, the suspension I can include 414-type basic magnesium carbonate and 415-type basic magnesium carbonate, and the pH value of the suspension I can be 9.2-9.6; the suspension II can include 414-type basic magnesium carbonate.

[0010] According to one or more exemplary embodiments of one aspect of the present application, the ammonia water and the CO2 can be simultaneously and uniformly injected into the refined magnesium sulfate solution; and the stirring and heating can be performed under a closed condition.

[0011] According to one or more exemplary embodiments of one aspect of the present application, the heating temperature can be 85-95℃; the stirring speed can be 0-60r / min, when the stirring speed is 0-10r / min, the crystal morphology of the 414-type basic magnesium carbonate can be spherical; and when the stirring speed is 10-60r / min, the crystal morphology of the 414-type basic magnesium carbonate can be corolla-shaped.

[0012] According to one or more exemplary embodiments of one aspect of the present application, the temperature of the cooling and aging can be 25-55℃, and the time can be 4-12h.

[0013] According to one or more exemplary embodiments of one aspect of the present application, the pH value of the impurity removal can be 7-8.

[0014] According to one or more exemplary embodiments of one aspect of the present application, the concentration of Mg 2+ in the refined magnesium sulfate solution can be 4.8-12g / L, and the concentration of other metal impurity ions can be 0.01-0.5g / L.

[0015] Another aspect of the present application provides a 414-type basic magnesium carbonate, which can be prepared by the above-mentioned preparation method of the 414-type basic magnesium carbonate, the crystal morphology of the 414-type basic magnesium carbonate can be spherical and / or corolla-shaped, and the particle size of the 414-type basic magnesium carbonate is inversely proportional to the molar ratio of the injection rate of the ammonia water and the CO2 into the refined magnesium sulfate solution.

[0016] Compared with the prior art, the present application has the following beneficial effects at least one of which is included:

[0017] (1) The preparation method of the 414-type basic magnesium carbonate solves the problems of complex process, difficult morphology control and low product purity in the existing preparation technology of basic magnesium carbonate;

[0018] (2) In the preparation method of the 414-type basic magnesium carbonate, ammonia water and CO2 are simultaneously introduced, and the basic magnesium carbonate is prepared by one-step method without pyrolysis, so that the process flow is simple and the operation is controllable;

[0019] (3) The preparation method of the 414 type basic magnesium carbonate provided by the application is a one-step method for preparing the 414 type basic magnesium carbonate from a magnesium sulfate solution, which can realize the resource utilization of CO2, and the product, the basic magnesium carbonate, is also an important chemical raw material. BRIEF DESCRIPTION OF DRAWINGS

[0020] The above and other objects and features of the present application will become more apparent from the following description made with reference to the accompanying drawings, in which:

[0021] Figure 1 An SEM image of the corolla-shaped basic magnesium carbonate of Example 1 of the application is shown;

[0022] Figure 2 An SEM image of the spherical basic magnesium carbonate of Example 2 of the application is shown;

[0023] Figure 3 An XRD image of the basic magnesium carbonate of Example 1 of the application is shown. DETAILED DESCRIPTION

[0024] Hereinafter, a 414 type basic magnesium carbonate and a preparation method thereof of the present application will be described in detail with reference to the accompanying drawings and exemplary embodiments.

[0025] Exemplary Embodiment 1

[0026] The present exemplary embodiment provides a preparation method of a 414 type basic magnesium carbonate.

[0027] The principle is that ammonia is added to the magnesium sulfate solution to adjust the pH to remove Al 3+ , Cr 3+ , Ni 2+ and other impurity ions. Ammonia and carbon dioxide are introduced into the refined magnesium sulfate solution to generate the basic magnesium carbonate, and the reaction formula is as follows:

[0028]

[0029] The preparation method of the 414 type basic magnesium carbonate mainly includes the following steps:

[0030] S1, ammonia is added to the magnesium sulfate solution to adjust the pH of the solution for impurity removal and precipitation, the suspension after impurity removal is filtered and diluted or concentrated to obtain a refined magnesium sulfate solution.

[0031] S2, ammonia and CO2 are injected into the refined magnesium sulfate solution, stirring and heating are performed, and after the injection is completed, a suspension I containing 414 type basic magnesium carbonate and 415 type basic magnesium carbonate is obtained.

[0032] S3, the suspension I is cooled and aged to obtain a suspension II containing 414 type basic magnesium carbonate.

[0033] S4, filtering the suspension II to obtain a filtrate and a residue, recycling the filtrate, and drying and dispersing the residue to obtain the basic magnesium carbonate of type 414.

[0034] In the present exemplary embodiment, in step S1, the concentration of the ammonia water added to the magnesium sulfate solution can be 3-5 mol / L, for example, 3 mol / L, 4 mol / L or 5 mol / L. The impurity-removing precipitation pH value can be 7-8, for example, 7, 7.5 or 8. Here, if the impurity-removing pH value is less than 7, the impurity ion removal rate will be low, and if the impurity-removing pH value is greater than 8, the loss rate of magnesium ions in the solution will increase.

[0035] In the present exemplary embodiment, in step S1, the concentration of Mg 2+ in the refined magnesium sulfate solution can be 4.8-12 g / L, for example, 5 g / L, 7 g / L or 11 g / L. If the concentration of magnesium ions is too high or too low, the generation rate of the basic magnesium carbonate will be affected. The concentration of other metal impurity ions can be 0.01-0.5 g / L, for example, 0.02 g / L, 0.35 g / L or 0.5 g / L. If the concentration of the impurity ions is too high, the purity of the final product will be affected. Here, the other metal impurity ions can include Al 3+ , Cr 3+ , Ni 2+ , Mn 2+ , Fe 3+ and Ca 2+ , etc.

[0036] In the present exemplary embodiment, in step S2, the refined magnesium sulfate solution obtained in step S1 can be placed in a closed reaction kettle with stirring and heating devices, and ammonia water and industrial-grade CO2 are simultaneously and uniformly injected into the refined magnesium sulfate solution in the reaction kettle.

[0037] Further, in step S2, to ensure that the ammonia water and CO2 are uniformly introduced into the reaction kettle, the ammonia water can be sprayed, and the CO2 can be uniformly introduced into the reaction kettle through an aeration pipe.

[0038] In the present exemplary embodiment, in step S2, the concentration of the ammonia water injected into the refined magnesium sulfate solution can be 1-3 mol / L, for example, 1 mol / L, 1.7 mol / L or 2.81 mol / L. Here, if the concentration of the ammonia water is too low, the concentration of the magnesium sulfate solution will decrease too much.

[0039] In the present exemplary embodiment, in step S2, after the injection of the ammonia water and CO2 is completed, the pH value of the suspension in the reaction kettle can be 9.2-9.6, for example, 9.2, 9.4 or 9.6. Here, if the pH value is too low, the magnesium precipitation rate will be low.

[0040] In the present exemplary embodiment, in step S2, the injection rate ratio of the ammonia water to the CO2 injected into the refined magnesium sulfate solution can be 1-4:1, for example, 1:1, 2:1, 3:1, or 4:1, in terms of molar ratio. Here, if the injection rate ratio of the ammonia water to the CO2 is too large, the final product is not the basic magnesium carbonate, and if the injection rate ratio is too small, the basic magnesium carbonate is not in a complete shape.

[0041] In the present exemplary embodiment, in step S2, the reaction temperature of the heating can be 85-95°C, for example, 86°C, 90°C, or 94°C. Here, if the reaction temperature is low, the precipitated product is magnesium carbonate trihydrate instead of the basic magnesium carbonate, and if the reaction temperature is too high, the energy consumption of the process is increased. The stirring speed can be 0-60 r / min, for example, 0 r / min, 20 r / min, or 40 r / min. Here, if the stirring speed is too large, the basic magnesium carbonate is destroyed.

[0042] Further, when the stirring speed is 0-10 r / min, the crystal morphology of the obtained 414-type basic magnesium carbonate can be spherical. When the stirring speed is 10-60 r / min, the crystal morphology of the obtained 414-type basic magnesium carbonate can be corolla-shaped.

[0043] In the present exemplary embodiment, in step S2, the ideal chemical formula of the 414-type basic magnesium carbonate can be 4MgCO3·Mg(OH)2·4H2O, and the ideal chemical formula of the 415-type basic magnesium carbonate can be 4MgCO3·Mg(OH)2·5H2O.

[0044] In the present exemplary embodiment, in step S3, the temperature of the cooling and aging can be 25-55°C, for example, 25°C, 35°C, or 48°C. Here, if the aging temperature is too low, the crystallization speed of the product is slow, and if the aging temperature is too high, the energy consumption is increased. The aging time can be 4-12 h, for example, 5 h, 8 h, or 11 h. Here, if the aging time is too short, the crystallization degree of the basic magnesium carbonate is poor, and if the aging time is too long, the overall process time is prolonged.

[0045] In the present exemplary embodiment, in step S4, the obtained 414-type basic magnesium carbonate can reach the standard of the first-class product or the superior product in HG / T 2959-2010 Industrial Hydrated Basic Magnesium Carbonate.

[0046] Exemplary Embodiment 2

[0047] The present exemplary embodiment provides a 414-type basic magnesium carbonate.

[0048] The 414-type basic magnesium carbonate can be prepared by the preparation method of the 414-type basic magnesium carbonate described in the above first exemplary embodiment.

[0049] In the present exemplary embodiment, the crystal morphology of the magnesium hydroxycarbonate of type 414 can be spherical and / or corolla-shaped. When it is spherical, the diameter of the spherical particles can be 5 μm to 14 μm, and the individual crystals constituting the spherical particles can be plate-shaped with a plate diameter of 14 nm to 20 nm. When it is corolla-shaped, the diameter of the corolla-shaped particles can be 5 μm to 30 μm, and the individual crystals constituting the corolla can be plate-shaped with a plate diameter of 10 nm to 16 nm.

[0050] In the present exemplary embodiment, the particle size of the magnesium hydroxycarbonate of type 414 can be inversely proportional to the molar ratio (NH3H2O / CO2) of the injection rate of the ammonia water and the CO2 into the purified magnesium sulfate solution.

[0051] For a better understanding of the above-described exemplary embodiment 2 of the present application, it will be further described below in connection with specific examples.

[0052] Example 1

[0053] Figure 1 An SEM image of the corolla-shaped magnesium hydroxycarbonate of Example 1 of the present application is shown; Figure 3 An XRD pattern of the magnesium hydroxycarbonate of Example 1 of the present application is shown.

[0054] To the magnesium sulfate solution, 3 mol / L ammonia water was added to adjust the pH value of the solution to 7.0, and the suspension after impurity removal was filtered to obtain a purified magnesium sulfate solution. The ion concentrations in the purified magnesium sulfate solution are shown in Table 1.

[0055] Table 1 Main chemical components of the purified magnesium sulfate solution

[0056] Element Mg Al Ca Cr Fe Ni Mn Concentration (g / L) 7.687 0.028 0.094 0.0025 0.008 0.045 0.022

[0057] The purified magnesium sulfate solution was placed in a closed reaction kettle with stirring and heating devices, 3 mol / L ammonia water was introduced in the form of spraying, industrial-grade CO2 was introduced through an aeration pipe, the introduction rate ratio (in terms of molar ratio) of the ammonia water and the CO2 was 1:1, the reaction was carried out at a stirring speed of 20 r / min and 85°C, and the reaction was stopped when the pH value of the reaction system was 9.2. After aging at 25°C for 4 h, the reaction product was filtered to obtain a filtrate and a filter residue, the filtrate can be recycled, and the filter residue is magnesium hydroxycarbonate. As shown in Table 2, it can be seen that the product prepared in Example 1 is magnesium hydroxycarbonate of type 414. Figure 3 As shown in Table 3, the magnesium hydroxycarbonate of type 414 prepared in Example 1 is corolla-shaped and has a complete morphology. The average particle size of the magnesium hydroxycarbonate of type 414 is 29.5 μm. Figure 1 As shown in Table 3, the magnesium hydroxycarbonate of type 414 prepared in Example 1 is corolla-shaped and has a complete morphology. The average particle size of the magnesium hydroxycarbonate of type 414 is 29.5 μm.

[0058] As shown in Table 3, the magnesium hydroxycarbonate of type 414 prepared in Example 1 is corolla-shaped and has a complete morphology. The average particle size of the magnesium hydroxycarbonate of type 414 is 29.5 μm.

[0059] The 414 type basic magnesium carbonate obtained in Example 1 was detected and compared with the first grade product standard as shown in Table 2. The basic magnesium carbonate meets the first grade product standard in HG / T 2959-2010 Industrial Hydrated Basic Magnesium Carbonate.

[0060] Table 2 Product detection

[0061] Item Test value Index (first grade) Magnesium oxide (MgO) w / % 41.1 40.0～43.5 Calcium oxide (CaO) w / % 0.30 ≤0.70 Hydrochloric acid insolubles w / % 0.09 ≤0.15 Moisture w / % 1.8 ≤3.0 Loss on ignition w / % 55 54～58 Chloride (as Cl) w / % 0.05 ≤0.10 Iron (Fe) w / % 0.008 ≤0.02 Manganese (Mn) w / % 0.001 ≤0.004 Sulphate (as SO4) w / % 0.10 ≤0.15 Fineness (0.15 mm) w / % 0.02 ≤0.03 Bulk density / (g / ml) 0.15 ≤0.2

[0062] Example 2

[0063] Figure 2 An SEM image of the spherical basic magnesium carbonate of Example 2 of the present application is shown.

[0064] 5 mol / L ammonia water was added to the magnesium sulfate solution to adjust the pH value of the solution to 8.0, and the impurity-removed suspension was filtered to obtain a refined magnesium sulfate solution. The ion concentrations in the refined magnesium sulfate solution are shown in Table 3.

[0065] Table 3 Main chemical components of the refined magnesium sulfate solution

[0066] Element Mg Al Ca Cr Fe Ni Mn Concentration (g / L) 12.0 0.050 0.025 0.0025 0.010 0.030 0.028

[0067] The refined magnesium sulfate solution was placed in a closed reaction kettle with stirring and heating devices, 1 mol / L ammonia water was introduced in a spraying manner, and industrial grade CO2 was introduced through an aeration pipe. The introduction rate ratio (in terms of molar ratio) of ammonia water and CO2 was 4:1, the stirring speed was 0 r / min, the reaction was carried out at 95°C, and the reaction was stopped when the pH value of the reaction system was 9.6. After aging at 55°C for 4 h, the reaction product was filtered to obtain a filtrate and a filter residue, the filtrate can be recycled, and the filter residue is the 414 type basic magnesium carbonate. As shown in Table 4, the 414 type basic magnesium carbonate obtained in Example 2 is spherical and has a complete morphology. Figure 2 The average particle size of the 414 type basic magnesium carbonate of Example 2 is 12.2 μm.

[0068] It can be seen that in the preparation method of Example 2, the stirring speed is 0 r / min, and the finally obtained 414 type basic magnesium carbonate is spherical.

[0069] The 414 type basic magnesium carbonate obtained in Example 2 was detected and compared with the first grade product standard as shown in Table 2. The basic magnesium carbonate meets the first grade product standard in HG / T 2959-2010 Industrial Hydrated Basic Magnesium Carbonate.

[0070] Table 4 Product detection

[0071]

[0072] Example 3

[0073] The pH value of the magnesium sulfate solution is adjusted to 8.0 by adding 5 mol / L ammonia water, and the suspension after impurity removal is filtered to obtain a refined magnesium sulfate solution. The ion concentration in the refined magnesium sulfate solution is shown in Table 5.

[0074] Table 5 Main chemical components of the refined magnesium sulfate solution

[0075] Element Mg Al Ca Cr Fe Ni Mn Concentration (g / L) 12.0 0.050 0.025 0.0025 0.010 0.030 0.028

[0076] The refined magnesium sulfate solution is placed in a sealed reaction kettle with stirring and heating device, and 2 mol / L ammonia water is sprayed into the reaction kettle. Industrial-grade CO2 is introduced through an aeration pipe, and the ratio of the introduction rate of ammonia water to CO2 (based on molar ratio) is 3:1. The reaction is carried out at a stirring speed of 60 r / min and a temperature of 90°C, and the reaction is stopped when the pH value of the reaction system is 9.4. After aging at 30°C for 12 h, the reaction product is filtered to obtain a filtrate and a filter residue. The filtrate can be recycled, and the filter residue is the 414 type basic magnesium carbonate. The obtained 414 type basic magnesium carbonate is in the form of a flower crown, and the average particle size is 18.3 μm.

[0077] As can be seen, in the preparation method of Example 3, the stirring speed is 60 r / min, and the finally obtained 414 type basic magnesium carbonate is in the form of a flower crown.

[0078] The 414 type basic magnesium carbonate obtained in Example 3 is detected and compared with the first-grade product standard as shown in Table 6. The basic magnesium carbonate meets the first-grade product standard in HG / T 2959-2010 Industrial Hydrated Basic Magnesium Carbonate.

[0079] Table 6 Product detection

[0080] Item Test value Index (first grade) Magnesium oxide (MgO) w / % 42.8 40.0～43.5 Calcium oxide (CaO) w / % 0.20 ≤0.70 Hydrochloric acid insolubles w / % 0.10 ≤0.15 Moisture w / % 2.0 ≤3.0 Loss on ignition w / % 56 54～58 Chloride (as Cl) w / % 0.03 ≤0.10 Iron (Fe) w / % 0.01 ≤0.02 Manganese (Mn) w / % 0.003 ≤0.004 Sulphate (as SO4) w / % 0.10 ≤0.15 Fineness (0.15 mm) w / % 0.02 ≤0.03 Bulk density / (g / ml) 0.16 ≤0.2

[0081] Example 4

[0082] The pH value of the magnesium sulfate solution is adjusted to 7.5 by adding 5 mol / L ammonia water, and the suspension after impurity removal is filtered to obtain a refined magnesium sulfate solution. The ion concentration in the refined magnesium sulfate solution is shown in Table 7.

[0083] Table 7 Main chemical components of the refined magnesium sulfate solution

[0084] Element Mg Al Ca Cr Fe Ni Mn Concentration (g / L) 4.80 0.020 0.013 0.0012 0.010 0.015 0.020

[0085] The refined magnesium sulfate solution is placed in a closed reaction kettle with stirring and heating device, 3 mol / L ammonia water is introduced in a spraying manner, industrial grade CO2 is introduced through an aeration pipe, the introduction rate ratio (in terms of molar ratio) of ammonia water and CO2 is 3:1, the reaction is carried out at a stirring speed of 60 r / min and 85°C, and the reaction is stopped when the pH value of the reaction system is 9.3. After aging at 40°C for 6 h, the reaction product is filtered to obtain a filtrate and a filter residue, the filtrate can be recycled, and the filter residue is the 414 type basic magnesium carbonate. The obtained 414 type basic magnesium carbonate is in the form of a flower crown, and the average particle size is 17.5 μm.

[0086] It can be seen that the stirring speed in the preparation method of Example 4 is 60 r / min, and the finally obtained 414 type basic magnesium carbonate is in the form of a flower crown.

[0087] The 414 type basic magnesium carbonate obtained in Example 4 is detected and compared with the first-grade product standard as shown in Table 8. The basic magnesium carbonate meets the first-grade product standard in HG / T 2959-2010 Industrial Hydrated Basic Magnesium Carbonate.

[0088] Table 8 Product detection

[0089] Item Test value Index (first grade) Magnesium oxide (MgO) w / % 41.8 40.0～43.5 Calcium oxide (CaO) w / % 0.20 ≤0.70 Hydrochloric acid insolubles w / % 0.10 ≤0.15 Moisture w / % 2.0 ≤3.0 Loss on ignition w / % 55 54～58 Chloride (as Cl) w / % 0.05 ≤0.10 Iron (Fe) w / % 0.01 ≤0.02 Manganese (Mn) w / % 0.002 ≤0.004 Sulphate (as SO4) w / % 0.08 ≤0.15 Fineness (0.15 mm) w / % 0.025 ≤0.03 Bulk density / (g / ml) 0.15 ≤0.2

[0090] Example 5

[0091] 4 mol / L ammonia water is added to the magnesium sulfate solution to adjust the pH value of the solution to 8.0, and the suspension after impurity removal is filtered to obtain a refined magnesium sulfate solution. The ion concentration in the refined magnesium sulfate solution is shown in Table 9.

[0092] Table 9 Main chemical components of the refined magnesium sulfate solution

[0093] Element Mg Al Ca Cr Fe Ni Mn Concentration (g / L) 8.82 0.005 0.030 0.0028 0.016 0.025 0.024

[0094] The refined magnesium sulfate solution is placed in a closed reaction kettle with stirring and heating device, 2 mol / L ammonia water is introduced in a spraying manner, industrial grade CO2 is introduced through an aeration pipe, the introduction rate ratio (in terms of molar ratio) of ammonia water and CO2 is 3:1, the reaction is carried out at a stirring speed of 60 r / min and 95°C, and the reaction is stopped when the pH value of the reaction system is 9.2. After aging at 55°C for 8 h, the reaction product is filtered to obtain a filtrate and a filter residue, the filtrate can be recycled, and the filter residue is the 414 type basic magnesium carbonate. The obtained 414 type basic magnesium carbonate is in the form of a flower crown, and the average particle size is 17.9 μm.

[0095] It can be seen that the stirring speed in the preparation method of Example 5 is 60 r / min, and the finally obtained 414 type basic magnesium carbonate is in the form of a flower crown.

[0096] The 414 type basic magnesium carbonate obtained in Example 5 was detected and compared with the superior product standard as shown in Table 10. The basic magnesium carbonate meets the superior product standard in HG / T 2959-2010 Industrial Hydrated Basic Magnesium Carbonate.

[0097] Table 10 Product detection

[0098]

[0099] Comparative Example 1

[0100] 4 mol / L ammonia water was added to the magnesium sulfate solution to adjust the pH value of the solution to 8.0. The suspension after impurity removal was filtered to obtain a refined magnesium sulfate solution. The ion concentration in the refined magnesium sulfate solution is shown in Table 11.

[0101] Table 11 Main chemical components of the refined magnesium sulfate solution

[0102] Element Mg Al Ca Cr Fe Ni Mn Concentration (g / L) 8.82 0.005 0.030 0.0028 0.016 0.025 0.024

[0103] The refined magnesium sulfate solution was placed in a closed reaction kettle with stirring and heating device. 2 mol / L ammonia water was introduced in the form of spraying, and industrial grade CO2 was introduced through an aeration pipe. The introduction rate ratio (in terms of molar ratio) of ammonia water and CO2 was 0.5:1. The reaction was carried out at a stirring speed of 60 r / min and 95℃. The reaction was stopped when the pH value of the reaction system was 9.2. The reaction product was aged at 55℃ for 8 h. After aging, the reaction product was filtered to obtain a filtrate and a filter residue. The obtained filter residue was 414 type basic magnesium carbonate, but the crystal morphology was low in integrity and the crystallinity was poor.

[0104] Comparative Example 1 and Example 5 only differ in the introduction rate ratio of ammonia water and CO2. In terms of molar ratio, the introduction rate of ammonia water and CO2 in Comparative Example 1 was 0.5:1. The product obtained in Comparative Example 1 was 414 type basic magnesium carbonate, but the crystal morphology was low in integrity and the crystallinity was poor. In Example 5, the introduction rate of ammonia water and CO2 was 3:1. The product obtained in Example 5 was 414 type basic magnesium carbonate, which was in the form of a flower crown and met the superior product standard in HG / T 2959-2010 Industrial Hydrated Basic Magnesium Carbonate. Therefore, it can be seen that too small introduction rate ratio of ammonia water and CO2 will result in incomplete morphology of basic magnesium carbonate.

[0105] Comparative Example 2

[0106] 4 mol / L ammonia water was added to the magnesium sulfate solution to adjust the pH value of the solution to 8.0. The suspension after impurity removal was filtered to obtain a refined magnesium sulfate solution. The ion concentration in the refined magnesium sulfate solution is shown in Table 12.

[0107] Table 12 Main chemical components of the refined magnesium sulfate solution

[0108] Element Mg Al Ca Cr Fe Ni Mn Concentration (g / L) 8.82 0.005 0.030 0.0028 0.016 0.025 0.024

[0109] The refined magnesium sulfate solution is placed in a closed reaction kettle with stirring and heating device, 2 mol / L ammonia water is sprayed into the reaction kettle, industrial grade CO2 is introduced through the aeration pipe, the ratio of the introduction rate of ammonia water and CO2 (in terms of molar ratio) is 5:1, the stirring speed is 60 r / min, the reaction is carried out at 95℃, and the reaction is stopped when the pH value of the reaction system is 9.2. After aging at 55℃ for 8h, the reaction product is filtered to obtain filtrate and filter residue, and the obtained filter residue is a mixture of basic magnesium carbonate and magnesium hydroxide.

[0110] Comparative Example 2 is compared with Example 5, and the preparation method of Comparative Example 2 is only different in the ratio of the introduction rate of ammonia water and CO2. The ratio of the introduction rate of ammonia water and CO2 of Comparative Example 2 is 5:1, and the product obtained by Comparative Example 2 is a mixture of basic magnesium carbonate and magnesium hydroxide. The ratio of the introduction rate of ammonia water and CO2 of Example 5 is 3:1, and the product obtained by Example 5 is 414 type basic magnesium carbonate, which is a corolla, and meets the standard of superior product in HG / T 2959-2010 Industrial Hydrated Basic Magnesium Carbonate. Therefore, it can be seen that too large ratio of the introduction rate of ammonia water and CO2 will result in that the final product is not pure basic magnesium carbonate.

[0111] In summary, the advantages of the present application include at least one of the following:

[0112] (1) The preparation method of 414 type basic magnesium carbonate provided by the present application has a simple process flow and controllable product morphology;

[0113] (2) The preparation method of 414 type basic magnesium carbonate provided by the present application uses CO2 as a carbon source to prepare basic magnesium carbonate, which provides a way for the recycling of CO2;

[0114] (3) The preparation method of 414 type basic magnesium carbonate provided by the present application can control the particle size of basic magnesium carbonate by controlling the introduction rate of ammonia water and CO2;

[0115] (4) The preparation method of 414 type basic magnesium carbonate provided by the present application can control the morphology of basic magnesium carbonate by controlling the stirring speed;

[0116] (5) The preparation method of 414 type basic magnesium carbonate provided by the present application has a magnesium ion precipitation rate higher than 90%, and a low loss rate of magnesium ions;

[0117] (6) The 414 type basic magnesium carbonate provided by the present application has complete morphology and uniform size.

[0118] While a 414-type basic magnesium carbonate and a method for producing the same according to an exemplary embodiment of the present application have been described above by combining the exemplary embodiments, it should be apparent to those skilled in the art that various modifications and changes can be made thereto without departing from the spirit and scope of the claims.

Claims

1. A process for the preparation of a 414 basic magnesium carbonate characterized in that, The preparation method comprises the following steps: The impurities are removed by adding ammonia water to the magnesium sulfate solution and adjusting the pH value, the suspension after the removal of impurities is filtered and diluted or concentrated to obtain a refined magnesium sulfate solution; the concentration of Mg 2+ in the refined magnesium sulfate solution is 4.8 g / L-12 g / L, and the concentration of other metal impurity ions is 0.01 g / L-0.5 g / L. ammonia water and CO2 are injected into a refined magnesium sulfate solution, stirring and heating are performed to obtain a suspension I; the pH value of the suspension I is 9.2-9.6; the injection rate ratio of the ammonia water and the CO2 injected into the refined magnesium sulfate solution is 1-4:1 in terms of molar ratio; the heating temperature is 85-95°C; and the stirring speed is 0-60 r / min; the suspension I is cooled and aged to obtain a suspension II; the suspension II is filtered to obtain a filtrate and a filter residue, and the filter residue is dried and dispersed to obtain the 414 basic magnesium carbonate; when the stirring speed is 0-10 r / min, the crystal morphology of the 414 basic magnesium carbonate is spherical, the diameter of the spherical particles is 5-14 μm, and the single crystal constituting the spherical particles is flaky with a flake diameter of 14-20 nm; when the stirring speed is 10-60 r / min, the crystal morphology of the 414 basic magnesium carbonate is corolla-shaped, the diameter of the corolla-shaped particles is 5-30 μm, and the single crystal constituting the corolla-shaped particles is flaky with a flake diameter of 10-16 nm.

2. The method of producing 414-hydrated magnesium subcarbonate according to claim 1, characterized in that, The concentration of the ammonia water added into the magnesium sulfate solution is 3-5 mol / L, and the concentration of the ammonia water injected into the refined magnesium sulfate solution is 1-3 mol / L.

3. The method of producing 414-hydrated magnesium subcarbonate according to claim 1, characterized by, The suspension I comprises the 414 basic magnesium carbonate and the 415 basic magnesium carbonate; and the suspension II comprises the 414 basic magnesium carbonate.

4. The method of producing 414-hydroxycarbonatomegnesium according to claim 1, characterized by, The ammonia water and the CO2 are simultaneously and uniformly injected into the refined magnesium sulfate solution; and the stirring and heating are performed under a closed condition.

5. The method of producing 414-hydrated magnesium subcarbonate according to claim 1, characterized by, The cooling and aging temperature is 25-55°C, and the time is 4-12 h.

6. The method of producing 414-hydrated magnesium subcarbonate according to claim 1, characterized by, The pH value of the impurity removal is 7-8.

7. A 414-type basic magnesium carbonate, characterized in that, The 414 basic magnesium carbonate is prepared by the preparation method of the 414 basic magnesium carbonate according to any one of claims 1-6, the crystal morphology of the 414 basic magnesium carbonate is spherical and / or corolla-shaped, and the particle size of the 414 basic magnesium carbonate is inversely proportional to the molar ratio of the injection rate of the ammonia water and the CO2 injected into the refined magnesium sulfate solution.

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