A high-purity, light-weight and highly active magnesium oxide and its preparation method

Abstract

The present invention relates to the technical field of pharmaceutical excipients, and particularly to a high-purity, light-weight and highly active magnesium oxide and a preparation method thereof, comprising the following steps: preparing a magnesium sulfate solution and a precipitant, stirring and mixing the magnesium sulfate solution and the precipitant in a high-speed spiral manner to obtain basic magnesium carbonate hydrate, and calcining the basic magnesium carbonate hydrate at a stepwise progressive temperature to obtain magnesium oxide. The present invention further refines and purifies the semi-finished products of the magnesium solution and the precipitant, adopts the method of the present invention to prepare a specific crystal form precursor, basic magnesium carbonate hydrate, and controls the calcination time node according to the stepwise progressive calcination method to obtain high-purity, light-weight and highly active magnesium oxide. Compared with the existing magnesium oxide products on the market, the high-purity, light-weight and highly active magnesium oxide prepared by the present invention has a higher magnesium oxide content, and better quality and service performance.

Description

Technical Field

[0001] The present invention relates to the technical field of pharmaceutical excipients, and particularly to a high-purity, light-weight and highly active magnesium oxide and a preparation method thereof. Background Art

[0002] The application of pharmaceutical-grade magnesium salt compounds in the pharmaceutical industry is basically divided into two categories: one is to use magnesium compounds as the main raw material and directly use them to manufacture drugs for neutralizing gastric acid, such as medical magnesium oxide, magnesium trisilicate, etc.; the other is to use magnesium compounds as excipients in the pharmaceutical industry.

[0003] The purity of pharmaceutical-grade magnesium oxide is relatively high, especially the content requirements for heavy metals such as lead, arsenic, cadmium, manganese and iron are relatively strict. The preparation methods of magnesium oxide can be roughly divided into three categories: liquid-phase method, solid-phase method and gas-phase method. At present, in the existing preparation process of pharmaceutical excipient magnesium oxide, there are still defects in the low purity of the prepared magnesium oxide, which cannot meet the needs of the existing pharmaceutical market for high-end magnesium oxide products. Thus, whether it is possible to produce magnesium oxide with light weight, high activity and high purity for use in granules and capsule preparations has become a technical problem that needs to be solved urgently by those skilled in the art. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention provides a high-purity, light-weight and highly active magnesium oxide as a new pharmaceutical excipient for capsule preparations. The prepared magnesium oxide has higher purity and activity, has good adhesion when mixed with capsule preparations, and becomes clear within 1 minute when reacting with citric acid, meeting the needs of the existing pharmaceutical market for high-end magnesium oxide products. The specific preparation method is as follows:

[0005] A preparation method of a high-purity, light-weight and highly active magnesium oxide, characterized by comprising the following steps:

[0006] Step 1: Take ammonium sulfate and light-burned magnesium oxide to carry out a distillation reaction to obtain a dilute magnesium slurry. Continue to add light-burned magnesium oxide to the dilute magnesium slurry, and add sulfuric acid to make the light-burned magnesium oxide react with sulfuric acid. After pressure filtration, purification precipitation and filtration, a magnesium sulfate solution is obtained;

[0007] Step 2: Take the ammonia water recovered by cooling the distillation reaction and introduce carbon dioxide to obtain carbonated ammonia water. Add ammonium bicarbonate to the carbonated ammonia water, and after precipitation and filtration, a precipitating agent is obtained;

[0008] Step 3: Pump the heated precipitating agent into a reaction kettle. Heat and pressurize the magnesium sulfate solution and add it to the reaction kettle in a spiral stirring manner. Add a crystal nucleus growth rate control agent. After heat aging and high-temperature dissolution to obtain a crystal liquid with crystals, separate, wash, dehydrate and dry the crystal liquid to obtain hydrated basic magnesium carbonate;

[0009] Step 4: Take the hydrated basic magnesium carbonate and calcine it at a stepwise progressive temperature to obtain magnesium oxide.

[0010] In step 1 of the method of the present invention, through a special acid addition method, impurities form high-valent basic oxides and metal hydroxide precipitates, which are adsorbed by the hydroxide colloid induced by the active metal oxide. Thus, the prepared magnesium oxide has higher purity. The ammonium bicarbonate added in step 2 is a food-grade precipitant. In step 3, the magnesium sulfate solution impacts the precipitant at high speed under the strong action of pressure and gravity to achieve an instant mixing reaction.

[0011] Further, the molar ratio of carbonate to ammonium ion of the precipitant prepared in step 2 is 44:100 to 47.5:100, and the concentration is 4.6 mol / L - 5.2 mol / L.

[0012] Further, in step 3, the concentration of the precipitant 4.6 mol / L - 5.2 mol / L is diluted to 4.1 - 4.2 mol / L, heated to 50 °C, and then pumped into the reaction kettle; the molar ratio of the magnesium sulfate solution to the precipitant in the reaction kettle is: 1:1.05 - 1:1.

[0013] Further, in step 3, the magnesium sulfate solution with a concentration of 1.9 mol / L - 2.1 mol / L is heated to 70 °C - 100 °C, pressurized to 0.4 Mpa, and then pumped into the reaction kettle in a spiral stirring manner.

[0014] Further, the molar ratio of the magnesium sulfate solution to the precipitant in the reaction kettle is: 1:1.05 - 1:1.

[0015] Further, in step 3, the time taken for the magnesium sulfate solution to be added to the reaction kettle is 8 s - 9 s, and the speed of spiral stirring is 2.5 m / s - 3 m / s.

[0016] Further, in step 3, the reaction temperature of the magnesium sulfate solution and the precipitant is 50 - 75 °C. When reacting for 2.5 min at this temperature, the crystal nucleus growth rate control agent is added within 15 s, and the mixed crystal liquid of crystals and ammonium sulfate is dissolved and released by pyrolysis at 100 °C.

[0017] Further, the crystal nucleus growth rate control agent is ammonium sulfate, and the volume ratio of ammonium sulfate in step 3 to ammonium sulfate in step 1 is 1:1.

[0018] The present invention screens the above optimal parameters of step 3 through a large number of creative experiments, thereby obtaining crystal shaping. After crystal liquid separation, washing, dehydration, and drying, a high-purity light magnesium carbonate, which is the precursor of high-purity light and highly active magnesium oxide with a specific and superimposed morphology, wrinkled outer dispersion, rough characterization, and a crystal form D50 of 11 microns, is prepared.

[0019] Further, the method of calcining at a stepwise progressive temperature includes the following stages: the temperature in stage 1 is 150°C - 400°C, the temperature in stage 2 is 400°C - 540°C, the temperature in stage 3 is 540°C - 700°C, and the temperature in stage 4 is 700°C.

[0020] Further, the sum of the calcination times used in stage 1 and stage 2 is 34% of the total calcination time; the calcination time used in stage 3 is 40% of the total calcination time; the calcination time used in stage 4 is 26% of the total calcination time.

[0021] Through a large number of creative experiments, the present invention screens the method steps of calcining in a stepwise progressive temperature in step 4, realizes the gradient decomposition and microscale disappearance of magnesium carbonate crystals, and the stepwise increase and solidification of magnesium oxide crystal nuclei, forming high-purity light and highly active magnesium oxide with a particle size D5 of 10 microns, a spherical crystal-like morphology feature, a rough surface with wrinkles, and a large apparent volume. The ignition loss of the prepared high-purity light and highly active magnesium oxide is 3.6 - 4.2%, and the magnesium oxide content reaches 99.8%.

[0022] A kind of high-purity light and highly active magnesium oxide is prepared by the above preparation method. The light and highly active magnesium oxide is used as a pharmaceutical excipient, in which the magnesium oxide content is 99.8%, CaO is 0.02%, SO₄²⁻ < 0.1%, Cl⁻ < 0.003%, FeO < 0.001%, MnO < 0.001%, heavy metals < 0.001%, arsenic salt < 0.0001%, acid-insoluble substances are 0.005%, soluble salts are 0.002%, ignition loss is 3.6%, apparent volume is 10 ml / g, and the activity value measured by citric acid is 15 s, meeting the standard requirements of "Light Magnesium Oxide" on pages 705 - 706 of Part IV of the Chinese Pharmacopoeia 2020 Edition.

[0023] The present invention further refines and purifies the semi-finished products of magnesium liquid and precipitant, adopts a special synthesis method to prepare a specific crystal form precursor, hydrated basic magnesium carbonate, and controls the calcination time nodes according to the stepwise progressive calcination method to prepare high-purity light and highly active magnesium oxide. Compared with the existing magnesium oxide products in the market, the prepared magnesium oxide by the present invention has a higher content, and both the quality and service performance are better. Description of the Drawings

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained according to these drawings.

[0025] Figure 1This is the SEM image of hydrated basic magnesium carbonate prepared in Example 1 of the present invention, magnified 3000 times at 1μm;

[0026] Figure 2 This is the SEM image of hydrated basic magnesium carbonate prepared in Example 1 of the present invention, magnified 5000 times at 1μm;

[0027] Figure 3 This is the SEM image of magnesium oxide prepared in Example 1 of the present invention, magnified 1000 times at 10μm;

[0028] Figure 4 This is the SEM image of magnesium oxide prepared in Example 1 of the present invention, magnified 5000 times at 1μm;

[0029] Figure 5 This is the SEM image of magnesium oxide prepared in Example 1 of the present invention, magnified 30000 times at 1μm; Detailed implementation manners

[0030] In order to better understand the above technical solutions, the above technical solutions will be described in detail below in conjunction with the accompanying drawings of the specification and specific implementation manners. Examples

[0031] A preparation method of high-purity light and highly active magnesium oxide includes the following steps:

[0032] Step 1: Ammonium sulfate and light-burned magnesium oxide (content MgO≥90%) are taken for distillation reaction to obtain a dilute magnesium slurry. Light-burned magnesium oxide is continuously added to the dilute magnesium slurry, and magnesium sulfate is obtained through acidolysis reaction. After pressure filtration, purification precipitation, and filtration, a magnesium sulfate solution with a concentration of 2.3mol / L - 2.5mol / L is obtained;

[0033] Step 2: The ammonia water cooled and recovered from the distillation reaction is taken and carbonated with 99.9% carbon dioxide to obtain carbonated ammonia water. Ammonium bicarbonate is added to the carbonated ammonia water, and after precipitation and filtration, a precipitating agent with a concentration of 4.6mol / L - 5.2mol / L is obtained. The molar ratio of carbonate radical to ammonium ion in the prepared precipitating agent is 44:100 to 47.5:100; the precipitating agent is food-grade ammonium bicarbonate;

[0034] Step 3: Dilute the precipitant concentration from 4.6 mol / L - 5.2 mol / L to 4.1 - 4.2 mol / L, heat it to 50°C, and then introduce it into the reaction kettle; heat the magnesium sulfate solution with a concentration of 1.9 mol / L - 2.1 mol / L to 70°C - 100°C, pressurize it to 0.4 Mpa, and then add it to the reaction kettle in a high-speed spiral stirring manner. The molar ratio of the magnesium sulfate solution to the precipitant in the reaction kettle is: 1:1.05 - 1:1. The magnesium sulfate solution impacts the precipitant in the reaction kettle at a speed of 2.5 m / s - 3 m / s for 8 s for instantaneous mixing reaction. The reaction temperature is 50 - 75°C. When the reaction lasts for 2.5 min, add the mother liquor ammonium sulfate crystal growth rate controller with 50% volume of the total reaction materials within 6 - 15 s, stir for 11 min, keep it at a constant temperature and stand for aging for 90 - 120 min to form crystal slurry. After stirring evenly, heat it to 95 - 110°C for pyrolytic dissolution and crystallization, and carry out shaping for 30 min to obtain crystal liquid. Separate, wash, dehydrate, and dry the crystal liquid to obtain basic magnesium carbonate hydrate; recycle the separated mother liquor ammonium sulfate for Step 1; the prepared basic magnesium carbonate hydrate has a specific and superimposed morphology, with wrinkles spreading outwards, a rough surface, D50 of 11 microns, and an apparent volume of 9.5 ml / g.

[0035] The basic magnesium carbonate hydrate prepared in this way shows a stacked flaky shape under the electron microscope. Its morphological characteristics are relatively unique and novel. Before the achievement of this R & D project, there was no basic magnesium carbonate hydrate produced by other public processes with such characteristics. The specific surface area of the basic magnesium carbonate hydrate prepared by this invention is larger, and it is easy to aggregate into spherical high-active magnesium oxide during calcination. The electron microscope structure is as Figure 1 and Figure 2 shown.

[0036] Step 4: Take the basic magnesium carbonate hydrate and calcine it at a stepwise progressive temperature to obtain magnesium oxide. The method of calcining at a stepwise progressive temperature includes the following stages: Stage 1 (150 - 400°C) is the stage of losing crystal water and decomposing magnesium hydroxide, and the time is controlled at 20% of the total time, that is, 17.2 min; Stage 2 (400 - 540°C) is the stage of thermal expansion of the material, and the time is controlled to account for 12.56% of the total time, that is, 10.8 min. Stage 3 (540 - 700°C) is the stage of decomposing water and the metastable state of basic magnesium carbonate to form the metastable form of magnesium oxide crystal, and the time is controlled to account for 30.35 - 30.23% of the total time, that is, 26 min. Stage 4 (700°C) is the stage of complete decomposition of magnesium carbonate to form the stable form of magnesium oxide crystal, and the decomposition time is controlled to account for 35.1 - 37.2% of the total time, that is, 30 - 32 min, to obtain magnesium oxide crystal powder with a spherical-like morphological feature, a rough surface with wrinkles, an apparent volume of 10 ml / g, and a particle size D50 of 10 microns. The electron microscope structure is as Figure 3 、 Figure 4 and Figure 5As shown, the activity value calculated based on the citric acid measurement value is 13 - 15 s, which can meet the standard requirements of "Light Magnesium Oxide" on pages 705 - 706 of Part Four of the Chinese Pharmacopoeia (2020 Edition).

[0037] For the magnesium hydrous basic carbonate produced by this process, when calcined in the above step - by - step progressive temperature manner to produce magnesium oxide, the activity effect is good. After testing, 3.5 g of magnesium oxide prepared by this invention is mixed evenly with 12 g of citric acid, and 150 ml of purified water is added for stirring. It can be completely dissolved within 1 minute, and the solution is clear. For the magnesium hydrous basic carbonate produced by other processes, under the same equipment conditions, the activity of the calcined magnesium oxide is poor. It takes more than 3 minutes to completely dissolve, and the solution is turbid and needs to stand for more than 15 minutes to become clear. Example

[0038] A preparation method of high - purity light high - activity magnesium oxide includes the following steps:

[0039] Step 1: Ammonium sulfate and light - calcined magnesium oxide (with MgO content ≥ 90%) are taken for a distillation reaction to obtain a dilute magnesium slurry. Light - calcined magnesium oxide is continuously added to the dilute magnesium slurry, and magnesium sulfate is obtained through an acidolysis reaction. After pressure filtration, purification precipitation, and filtration, a magnesium sulfate solution with a concentration of 2.3 mol / L is obtained;

[0040] Step 2: The ammonia water recovered by cooling the distillation reaction is introduced into 99.9% carbon dioxide to obtain carbonated ammonia water. Ammonium bicarbonate is added to the carbonated ammonia water, and after precipitation and filtration, a precipitant with a concentration of 4.6 mol / L - 5.2 mol / L is obtained. The molar ratio of carbonate to ammonium ion in the prepared precipitant is 44:100; the precipitant is food - grade ammonium bicarbonate;

[0041] Step 3: 2200 L of the precipitant diluted to 4.1 mol / L is pumped into the precipitant addition tank and heated to 50 °C; then 2000 L of the magnesium sulfate solution diluted to 2.05 mol / L is pumped into the magnesium sulfate solution pressure - heating tank, heated to 70 °C, and adjusted to a pressure of 0.4 MPa. Then the precipitant is put into the reaction kettle, the spiral stirrer is started, the rotation speed is adjusted, the solenoid valve of the magnesium sulfate solution pressure - heating tank is opened, and the heated magnesium sulfate solution is added to the precipitant in the reaction kettle within 8 s. When reacting at 60 °C for 2.5 min, 2100 L of the mother liquor of the crystal nucleus growth rate - controlling agent ammonium sulfate is added within 15 s, the stirring reaction is stopped after 11 min, and static precipitation is carried out at 60 °C for 90 min. After the static precipitation is completed, the stirring is started to stir the slurry evenly, the slurry is heated to 100 °C for pyrolysis dissolution and crystal shaping for 30 min, and crystal - liquid separation is carried out. The separated liquid ammonium sulfate is recovered for distillation use, and the crystal material is washed, separated, and dried to obtain a precursor magnesium hydrous basic carbonate with a specific and superimposed morphology, wrinkled and outward - spreading appearance, rough surface, D50 of 10 microns, and an apparent volume of 8 ml / g.

[0042] Step 4: Remove all crystal water from the precursor magnesium carbonate hydroxide material, completely decompose magnesium hydroxide, perform thermal expansion pre-decomposition at a temperature of 400 - 540 °C for 8.8 min, then perform calcination decomposition at a temperature of 540 - 700 °C for 26 min to form metastable crystalline magnesium oxide, and then perform isothermal calcination at 700 °C for 32 min to obtain high-purity light and highly active magnesium oxide.

[0043] After testing, the composition of the magnesium oxide prepared in this example according to the above method is as follows: MgO is 99.8%, CaO is 0.02%, SO₄²⁻ < 0.1%, Cl⁻ < 0.003%, FeO < 0.004%, MnO < 0.001%, heavy metals < 0.001%, arsenic salt < 0.0001%, insoluble matter in acid is 0.005%, soluble salt 0.002%, ignition loss 3.6%, apparent volume 8.5 ml / g, activity value measured by citric acid is 16 s. It can meet the standard requirements of "Light Magnesium Oxide" on pages 705 - 706 of the fourth part of the Chinese Pharmacopoeia 2020 edition. Example

[0044] A preparation method of high-purity light and highly active magnesium oxide, comprising the following steps:

[0045] Step 1: Take ammonium sulfate and light-burned magnesium oxide (content MgO ≥ 90%) to carry out a distillation reaction to obtain a dilute magnesium slurry, continue to add light-burned magnesium oxide to the dilute magnesium slurry, carry out an acidolysis reaction to obtain magnesium sulfate, and obtain a magnesium sulfate solution with a concentration of 2.4 mol / L through pressure filtration, purification precipitation, and filtration;

[0046] Step 2: Take the ammonia water recovered by cooling the distillation reaction and introduce 99.9% carbon dioxide to obtain carbonated ammonia water, add ammonium bicarbonate to the carbonated ammonia water, and obtain a precipitating agent with a concentration of 4.8 mol / L through precipitation and filtration. The molar ratio of carbonate to ammonium ion in the prepared precipitating agent is 46:100; the precipitating agent is food-grade ammonium bicarbonate;

[0047] Step 3: Pour 2200 L of precipitant, diluted to 4.1 mol / L, into the precipitant tank and heat to 50°C. Then, pour 2000 L of magnesium sulfate solution, diluted to 2.05 mol / L, into the magnesium sulfate solution pressure heating tank and heat to 85°C and 0.4 MPa. Then, place the precipitant into the reactor, start the spiral agitator, adjust the speed, open the solenoid valve of the magnesium sulfate solution pressure heating tank, and add the heated magnesium sulfate solution to the precipitant in the reactor over 8 seconds. After reacting at 60°C for 2.5 minutes, add 2100 L of ammonium sulfate, the mother liquor for the rate-controlling agent for nucleation growth, over 15 seconds. Stir the reaction for 11 minutes, then stop stirring. Keep at 67.5°C and allow to settle for 90 minutes. After settling, stir the slurry until uniform, then heat it to 100°C for 30 minutes of pyrolysis, dissolution, and crystallization, followed by crystal-liquid separation. Liquid ammonium sulfate is separated and recovered for distillation. The crystal material is washed, separated, and dried to obtain a precursor hydrated basic magnesium carbonate with a specific superposition morphology, scattered wrinkles, a rough surface, a D5O of 10 microns, and an apparent volume of 8 ml / g.

[0048] Step 4: The precursor hydrated magnesium carbonate material is completely decomposed by removing all crystal water and magnesium hydroxide, pre-decomposing it by thermal expansion at a temperature of 400-540°C for 8.8 minutes, then calcining it at a temperature of 540-700°C for 26 minutes to decompose it into metastable crystalline magnesium oxide, and then calcining it at a constant temperature of 700°C for 32 minutes to obtain a high-purity, lightweight, and highly active magnesium oxide for pharmaceutical excipients of this patent.

[0049] The magnesium oxide prepared according to the above method in this embodiment was tested to have the following composition: MgO 99.8%, CaO 0.02%, SO₄₂<0.1%, Cl₄<0.003%, FeO<0.004%, MnO<0.001%, heavy metals<0.001%, arsenic salts ≤0.0001%, acid insoluble matter 0.005%, soluble salts 0.002%, loss on ignition 3.7%, apparent volume 9.0 ml / g, and activity value measured with citric acid of 15 s. This meets the standard requirements for "light magnesium oxide" in the 2020 edition of the Chinese Pharmacopoeia, Part IV, pages 705-706. Example

[0050] A method for preparing high-purity, lightweight and highly active magnesium oxide comprises the following steps:

[0051] Step 1: ammonium sulfate and light-burned magnesium oxide (MgO content ≥ 90%) are distilled to obtain a dilute magnesium slurry, light-burned magnesium oxide is further added to the dilute magnesium slurry, magnesium sulfate is obtained by acid hydrolysis, and the magnesium sulfate solution with a concentration of 2.5 mol / L is obtained by filtration, purification, precipitation, and filtration;

[0052] Step 2: Take the ammonia water recovered by cooling the distillation reaction and introduce 99.9% carbon dioxide to obtain carbonated ammonia water. Add ammonium bicarbonate to the carbonated ammonia water, and after precipitation and filtration, obtain a precipitating agent with a concentration of 5.2 mol / L. The molar ratio of carbonate to ammonium ion in the prepared precipitating agent is 7.5:100; the precipitating agent is food-grade ammonium bicarbonate;

[0053] Step 3: Pump 2200 L of the precipitating agent diluted to 4.1 mol / L into the precipitating agent addition tank and heat it to 50 °C; then pump 2000 L of magnesium sulfate solution diluted to 2.05 mol / L into the magnesium sulfate solution pressure and heating tank, heat it to 100 °C, and adjust the pressure to 0.4 MPa. Then put the precipitating agent into the reaction kettle, start the spiral stirring, adjust the rotation speed, open the solenoid valve of the magnesium sulfate solution pressure and heating tank, and add the heated magnesium sulfate solution to the precipitating agent in the reaction kettle within 8 s. When reacting at 60 °C for 2.5 min, add 2100 L of the mother liquor of the crystal nucleus growth rate control agent ammonium sulfate within 15 s, stir and react for 11 min, then stop stirring, and keep it static and aged at 75 °C for 90 min. After the static aging is completed, start the stirring to mix the slurry evenly, heat the slurry to 100 °C for 30 min for thermal decomposition, dissolution, crystallization and shaping, and then perform crystal-liquid separation. The separated liquid ammonium sulfate is recovered for distillation, and the crystal material is washed, separated and dried to obtain a precursor basic magnesium carbonate hydrate with a specific and superimposed morphology, scattered folds, rough appearance, D50 of 10 μm, and an apparent volume of 8 ml / g.

[0054] Step 4: Remove all the crystal water from the precursor basic magnesium carbonate material and completely decompose magnesium hydroxide. After thermal expansion and pre-decomposition at a temperature of 400 - 540 °C for 8.8 min, then calcine and decompose it at a temperature of 540 - 700 °C for 26 min to form metastable crystalline magnesium oxide, and then calcine it at a constant temperature of 700 °C for 32 min to obtain a high-purity, light and highly active magnesium oxide for pharmaceutical excipients of this patent.

[0055] The magnesium oxide prepared according to the above method in this example was detected and its composition is as follows: MgO is 99.8%, CaO is 0.02%, SO₄²⁻ < 0.1%, Cl⁻ < 0.003%, FeO < 0.004%, MnO < 0.001%, heavy metals < 0.001%, arsenic salt < 0.0001%, insoluble matter in acid is 0.005%, soluble salt is 0.002%, ignition loss is 4.0%, apparent volume is 10 ml / g, and the activity value measured by citric acid is 14 s. It can meet the requirements of the "Light Magnesium Oxide" standard on pages 705 - 706 of Part Four of the Chinese Pharmacopoeia 2020 Edition.

[0056] From the analysis results of the detected components of the magnesium oxide prepared in the above examples, it can be seen that the preparation method of the magnesium oxide for pharmaceutical excipients provided by the present invention has the characteristics of being light and highly active, low preparation cost, high purity of the prepared magnesium oxide, and can meet the current market demand for magnesium oxide for pharmaceutical excipients.

[0057] Although the preferred embodiments of the present invention have been described, additional changes and modifications can be made to these embodiments by those skilled in the art once they learn of the basic creative concept. Therefore, the appended claims are intended to be construed to include the preferred embodiments as well as all changes and modifications that fall within the scope of the present invention.

[0058] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these modifications and variations.

Claims

1. A method for preparing high-purity, lightweight and highly active magnesium oxide, characterized in that: The following steps are involved: Step 1: dilute magnesium slurry is prepared by distilling ammonium sulfate and light-burned magnesium oxide, and light-burned magnesium oxide is further added to the dilute magnesium slurry to obtain magnesium sulfate through acid hydrolysis, and then filtered, purified, precipitated, and filtered to obtain a magnesium sulfate solution; Step 2: taking the ammonia water recovered by cooling the distillation reaction, introducing carbon dioxide into the ammonia water to obtain carbonated ammonia water, adding ammonium bicarbonate to the carbonated ammonia water, and obtaining a precipitant through precipitation and filtration, wherein the precipitant has a carbonate to ammonium ion molar ratio of 44:100 to 47.5:100 and a concentration of 4.6 mol / L-5.2 mol / L; Step 3: dilute the precipitant concentration from 4.6mol / L to 5.2mol / L to 4.1-4.2mol / L, heat the precipitant to 50°C and inject it into the reactor, heat the magnesium sulfate solution with a concentration of 1.9mol / L to 2.1mol / L to 70°C to 100°C, pressurize it to 0.4Mpa and inject it into the reactor with spiral stirring, the molar ratio of magnesium sulfate solution to precipitant in the reactor is 1:1.05-1:1, The time taken for adding the magnesium sulfate solution to the reactor is 8s-9s, the speed of the spiral stirring is 2.5m / s-3m / s, the reaction temperature of the magnesium sulfate solution and the precipitant is 50-75°C, and when the reaction is carried out under this temperature condition for 2.5 minutes, a crystal nucleus growth rate controller is added within 6-15s, wherein the crystal nucleus growth rate controller is ammonium sulfate, and a mixed crystal liquid of crystals and ammonium sulfate is dissolved by thermal decomposition, and the crystal liquid is separated, washed, dehydrated, and dried to obtain hydrated basic magnesium carbonate; Step 4: calcining the hydrated basic magnesium carbonate at a stepwise temperature to obtain magnesium oxide.

2. The method for preparing high-purity, lightweight and highly active magnesium oxide according to claim 1, wherein: The added volume ratio of the ammonium sulfate in the step 3 to the ammonium sulfate in the step 1 is 1:

1.

3. The method for preparing high-purity, lightweight and highly active magnesium oxide according to claim 1, wherein: The step-by-step temperature calcination method includes the following stages: stage 1 temperature is 150°C-400°C, stage 2 temperature is 400°C-540°C, stage 3 temperature is 540°C-700°C, and stage 4 temperature is 700°C.

4. The method for preparing high-purity, lightweight and highly active magnesium oxide according to claim 3, wherein: The sum of the calcination time used in the stage 1 and the stage 2 is 34% of the total calcination time; the calcination time used in the stage 3 is 40% of the total calcination time; and the calcination time used in the stage 4 is 26% of the total calcination time.

5. A high-purity, lightweight and highly active magnesium oxide, characterized by: The invention is prepared by the preparation method according to any one of claims 1 to 4.

Images