CN112028093A - Preparation method of high-activity high-purity magnesium oxide - Google Patents
Preparation method of high-activity high-purity magnesium oxide Download PDFInfo
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
- C01F5/00—Compounds of magnesium
- C01F5/02—Magnesia
- C01F5/06—Magnesia by thermal decomposition of magnesium compounds
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B02—CRUSHING, PULVERISING, OR DISINTEGRATING; PREPARATORY TREATMENT OF GRAIN FOR MILLING
- B02C—CRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; MILLING GRAIN
- B02C21/00—Disintegrating plant with or without drying of the material
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2/00—Lime, magnesia or dolomite
- C04B2/10—Preheating, burning calcining or cooling
- C04B2/102—Preheating, burning calcining or cooling of magnesia, e.g. dead burning
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- C01P2002/70—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data
- C01P2002/72—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data by d-values or two theta-values, e.g. as X-ray diagram
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- C01P2004/00—Particle morphology
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- C01P2004/03—Particle morphology depicted by an image obtained by SEM
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- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/12—Surface area
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- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/80—Compositional purity
Abstract
The invention discloses a preparation method of high-activity high-purity magnesium oxide, belonging to the technical field of mineral resource processing. The preparation method comprises the following steps: (1) cleaning magnesite: taking low-grade magnesite as a raw material, and cleaning; (2) refining magnesite: refining the magnesite cleaned in the step (1), wherein the refining comprises crushing the magnesite, roasting the crushed magnesite, grinding the magnesite, adding water into the ground magnesite to prepare raw ore pulp, desliming the raw ore pulp and floating the deslimed raw ore pulp to obtain concentrate powder; (3) calcining magnesite: calcining the concentrate powder; (4) fine grinding of magnesite: and (4) fine grinding and activating the calcined concentrate powder. Compared with the prior art, the test parameters such as the bulk density, the content of active magnesium oxide, the content of calcium oxide, the content of hydrochloric acid insoluble substances, the content of chloride, the ignition loss and the like show significant differences, and the magnesium oxide is high-quality high-activity high-purity magnesium oxide.
Description
Technical Field
The invention belongs to the technical field of mineral resource processing, and particularly relates to a preparation method of high-activity high-purity magnesium oxide.
Background
In recent years, in order to adapt to the increasing development of high-temperature industries such as steel, cement, chemical industry, glass and the like, improve the service life of industrial kilns and reduce the cost of refractory materials, efficient and high-quality magnesium-based refractory materials are actively developed at home and abroad. In the case of magnesite, the trend is toward high purity (MgO. gtoreq.99%), densification (bulk density. gtoreq.3.50 g/cm)3). At present, the magnesite products in China are mainly low-grade and primary products, the products are sold at low price, the serious waste of mineral resources is caused, foreign magnesium oxide products tend to be diversified and refined, and the primary product yield is very low. From the structure of the magnesite product, about 80 percent of the annual output of the whole industry in China is low-grade and primary products, less than 1 percent of the annual output is high-value-added magnesium material, and especially high-purity magnesite (more than 3.40 g/cm)3) And large crystal electro-fused magnesite in a small proportion. The high-end magnesite in China is mainly fused magnesite and is supplemented by high-purity sintered magnesite. The high-purity sintered magnesite product is used for bottom of furnace and lining of ramming furnace, and is produced with high-purity magnesium hydroxide, and has high purity, high density and high temperature performance, and may be used in making brickThe refractory material is also a raw material of high-temperature furnace lining refractory materials in the industries of steel, nonferrous metallurgy, refractory materials, glass, cement and the like. Although the production of the high-purity sintered magnesite is compared with the production of the fused magnesite, the production method has the advantages of low energy consumption, low labor intensity, stable quality, high automation degree, good thermal shock resistance and the like. But because the high-purity sintered magnesite is difficult to sinter, the volume density is lower (generally 3.25 g/cm)3) And the like, and cannot replace the fused magnesite. Because the domestic magnesite products have more raw products, more low-grade products, and less high-grade and functional products. Therefore, the magnesite products with high purity, high volume density and high performance are still the first development in China, and only then does the magnesite industry have wide market prospect. The traditional active magnesium oxide is produced from natural magnesite in Liaoning area of China, the magnesite is calcined in a reflection kiln, and then ground, and the like, so that the produced magnesium oxide has low activity, and high-density and high-purity magnesite is difficult to produce by using the magnesium oxide.
The Liaoning magnesite new material industrial base in Haicheng has large storage amount of magnesite tailing resources, high-grade magnesium resources can be obtained through flotation and purification, and the activity of magnesium oxide can be greatly improved by adopting a suspension furnace for production, so that necessary objective conditions are provided for the Liaoning magnesite industry development. The magnesite tailings with low cost are used for producing high-purity magnesite with high added value, so that the development of the refractory material industry in China can be promoted, and the advantages of magnesium resources in China can be effectively utilized. Therefore, the project makes full use of the basic conditions of the magnesite tailing flotation and purification patent technology of the company, the novel suspension furnace and the like to research and develop the volume density of 3.35g/cm3The high-purity magnesite replaces fused magnesite, so that the blank of high-end products of magnesite industry in Liaoning areas is filled, and comprehensive development and cyclic utilization of magnesite tailing resources in areas are promoted to take a new step. Specifically, the key of the first step of developing high-density high-purity magnesite is to produce high-activity high-purity magnesia, the project utilizes the magnesite tailing flotation purification patent technology of the company to prepare concentrate powder, the concentrate powder is used as a raw material and directly calcined by a suspension furnace, and the concentrate powder is subjected to fine grinding and activation, so that the obtained product has high activity; the second part is to apply a suspension furnace to produce the blast bodyThe technological parameters of the dense high-purity magnesite determine whether an active magnesia product with stable quality can be obtained. The innovation point of the project is that the suspension furnace is utilized to research and produce the high-density and high-purity magnesia through the research and development of the high-activity and high-purity magnesia, the optimization test of the production process parameters of the suspension furnace and the like.
Disclosure of Invention
1. Problems to be solved
Aiming at the problems in the prior art, the invention provides the preparation method of the high-activity high-purity magnesium oxide, which has good performance advantages compared with the prior art, and the high-activity high-purity magnesium oxide has significant differences in test parameters such as bulk density, active magnesium oxide content, calcium oxide content, hydrochloric acid insoluble content, chloride content, ignition loss and the like, and is high-quality high-activity high-purity magnesium oxide.
2. Technical scheme
In order to solve the problems, the technical scheme provided by the invention is as follows:
a preparation method of high-activity high-purity magnesium oxide comprises the following steps:
(1) cleaning magnesite: taking low-grade magnesite as a raw material, cleaning, and removing mud and micro-fine particle minerals on the surface of the magnesite for later use;
(2) refining magnesite: refining the magnesite cleaned in the step (1), wherein the refining process is divided into six steps, the first step is to crush the magnesite, the second step is to roast the crushed magnesite, the third step is to grind the roasted magnesite, the fourth step is to add water into the grinded magnesite to prepare raw ore pulp, the fifth step is to desliming the raw ore pulp, and the sixth step is to perform flotation on the deslimed raw ore pulp to obtain refined ore powder for later use;
(3) calcining magnesite: calcining the concentrate powder prepared in the step (2) for later use;
(4) fine grinding of magnesite: and (4) fine grinding and activating the calcined concentrate powder in the step (3).
In the preparation method of the high-activity high-purity magnesia, the mass percent range of the magnesite in the low-grade magnesite in the step (1) is 30-45%, wherein the mass percent range of the dolomite is 10-30%, the mass percent range of the quartz is 5-15%, and the balance is other mineral impurities.
In the preparation method of the high-activity high-purity magnesium oxide, the particle size fraction of the crushed magnesite in the step (2) is 5-10 mm; the roasting equipment in the step (2) is a rotary kiln or a fluidized bed furnace; the grinding equipment in the step (2) is a ball mill, and the rotating speed of the ball mill is 50 r/min; the ground particle size in the step (2) is 0.1mm-0.3 mm; the desliming equipment in the step (2) is a desliming cyclone; the water content of the concentrate powder in the step (2) is less than 20 percent, and the MgO content is 45 to 50 percent.
In the preparation method of the high-activity high-purity magnesium oxide, the flotation device in the step (2) is a flotation tank, the flotation tank is divided into a dosing reaction zone, a standing aeration separation zone, a concentrate collecting tank, a tailing tank and a tailing collecting tank by a wall plate, the bottom surface of the dosing reaction zone is an inclined plane, one side of the dosing reaction zone, which is close to the standing aeration separation zone, is inclined downwards, the top of the dosing reaction zone is provided with an electric stirrer, the lower part of the outer side wall of the dosing reaction zone is provided with an ore pulp inlet, the wall plate between the standing aeration separation zone and the dosing reaction zone is provided with a mixed ore pulp inlet, the lifting pump is connected through a pipeline, the bottom of the standing aeration separation zone is provided with a bubble generator, one side of the tailing tank is provided with a tailing collecting device, the top of the standing.
In the preparation method of the high-activity high-purity magnesium oxide, the flotation condition in the step (2) is to add a dispersing agent and a collecting agent and adjust the pH value.
In the preparation method of the high-activity high-purity magnesium oxide, the calcining equipment in the step (3) is a suspension furnace, the operating temperature of the suspension furnace is 900-1100 ℃, the air flow of the suspension furnace is 500-1200 mL/s, and the air pressure of the suspension furnace is 1 MPa; the calcining time in the step (3) is 2h-3 h.
In the preparation method of the high-activity high-purity magnesium oxide, the fine grinding equipment in the step (4) is a ball mill, and the rotating speed of the ball mill is 70 r/min; the particle size after the fine grinding in the step (4) is 0.1-0.3 μm.
3. Advantageous effects
Compared with the prior art, the invention has the beneficial effects that:
compared with the prior art, the magnesium oxide prepared by the invention has good performance advantages, and the test parameters such as bulk density, active magnesium oxide content, calcium oxide content, hydrochloric acid insoluble content, chloride content, ignition loss and the like show significant differences, and is high-quality, high-activity and high-purity magnesium oxide. Specifically, the invention fully utilizes the basic conditions of magnesite tailing flotation purification and novel suspension furnace, and the like applied by the company in the prior art, researches and develops the volume density of 3.35g/cm3The high-purity magnesite replaces fused magnesite, so that the blank of high-end products of magnesite industry in Liaoning areas is filled, and comprehensive development and cyclic utilization of magnesite tailing resources in areas are promoted to take a new step.
Drawings
FIG. 1 is an SEM scan of magnesium oxide prepared in example 1 of the present invention;
FIG. 2 is an XRD scan of the magnesium oxide prepared in example 1 of the present invention.
Detailed Description
The invention is further described with reference to specific embodiments and the accompanying drawings.
Example 1
The preparation method of the high-activity high-purity magnesium oxide comprises the following steps:
(1) cleaning magnesite: taking low-grade magnesite as a raw material, cleaning, and removing mud and micro-fine particle minerals on the surface of the magnesite for later use;
(2) refining magnesite: refining the magnesite cleaned in the step (1), wherein the refining process is divided into six steps, the first step is to crush the magnesite, the second step is to roast the crushed magnesite, the third step is to grind the roasted magnesite, the fourth step is to add water into the grinded magnesite to prepare raw ore pulp, the fifth step is to desliming the raw ore pulp, and the sixth step is to perform flotation on the deslimed raw ore pulp to obtain refined ore powder for later use;
(3) calcining magnesite: calcining the concentrate powder prepared in the step (2) for later use;
(4) fine grinding of magnesite: and (4) fine grinding and activating the calcined concentrate powder in the step (3).
In the preparation method of the high-activity high-purity magnesia, the mass percent range of the magnesite in the low-grade magnesite in the step (1) is 35%, wherein the mass percent range of the dolomite is 10% -30%, the mass percent range of the quartz is 10%, and the balance is other mineral impurities.
In the preparation method of the high-activity high-purity magnesium oxide, the particle size fraction of the crushed magnesite in the step (2) is 8 mm; the roasting equipment in the step (2) is a rotary kiln or a fluidized bed furnace; the grinding equipment in the step (2) is a ball mill, and the rotating speed of the ball mill is 50 r/min; the ground particle size in the step (2) is 0.2 mm; the desliming equipment in the step (2) is a desliming cyclone; the water content of the concentrate powder in the step (2) is less than 20 percent, and the MgO content is 48 percent.
In the preparation method of the high-activity high-purity magnesium oxide, the flotation device in the step (2) is a flotation tank, the flotation tank is divided into a dosing reaction zone, a standing aeration separation zone, a concentrate collecting tank, a tailing tank and a tailing collecting tank by a wall plate, the bottom surface of the dosing reaction zone is an inclined plane, one side of the dosing reaction zone, which is close to the standing aeration separation zone, is inclined downwards, the top of the dosing reaction zone is provided with an electric stirrer, the lower part of the outer side wall of the dosing reaction zone is provided with an ore pulp inlet, the wall plate between the standing aeration separation zone and the dosing reaction zone is provided with a mixed ore pulp inlet, the lifting pump is connected through a pipeline, the bottom of the standing aeration separation zone is provided with a bubble generator, one side of the tailing tank is provided with a tailing collecting device, the top of the standing. This section is prior art to the present company, application No.: CN201521098716.6, publication No.: CN205436031U discloses a flotation device for low-grade magnesite, which comprises a flotation tank, wherein the flotation tank is divided into a dosing reaction area 1, a standing and aerating separation area 2, a concentrate collecting tank 3, a tailing tank 4 and a tailing collecting tank 5 by a wall plate, the bottom surface of the dosing reaction area 1 is an inclined surface, and one side of the dosing reaction area close to the standing and aerating separation area 2 is inclined downwards; the top of the dosing reaction zone 1 is provided with an electric stirrer 6, and the lower part of the outer side wall is provided with an ore pulp inlet 8; a mixed ore pulp inlet 12 is arranged on a wall plate between the standing aeration separation area 2 and the dosing reaction area 1 and is connected with a lift pump 15 through a pipeline, a bubble generator 14 is arranged at the bottom of the standing aeration separation area 2, and a tailing collecting device 17 is arranged at one side close to the tailing pond 4; the top of the standing aeration separation area 2 is communicated with a concentrate collecting tank 5, and the upper part of the communicated part is provided with a slag scraper 16; the top of the tailing pond 4 is communicated with a tailing collecting groove 5. The bubble generator 14 is connected with the water pump 10 through a first connecting pipeline 19, the water pump 10 is connected with the dosing reaction area 1 through a second connecting pipeline 20, an opening and closing valve 11 is arranged on the first connecting pipeline 19, and a filter 9 is arranged on the second connecting pipeline 20. The electric stirrer 6 is controlled by a variable frequency motor 7. A liquid level regulator 18 is arranged at the separation part of the tailing pond 4 and the tailing collecting groove 5. The tailing collecting device 17 is composed of a plurality of collecting pipes arranged side by side, the other ends of the collecting pipes extend into the tailing pond 4, and a plurality of through holes are uniformly formed in each collecting pipe along the radial direction and the axial direction. The bubble generators 14 are arranged side by side, liquid inlet pipes at the bottoms of the bubble generators 14 are fixed on the connecting main pipe 13, and the connecting main pipe 13 is communicated with the first connecting pipeline 19. When the chemical adding device is used, ore pulp enters the chemical adding reaction area 1 from the ore pulp inlet 8, the electric stirrer 6 is started, and flotation reagents such as a dispersing agent, a collecting agent, a pH value regulator and the like are respectively added in a stirring state, so that the flotation reagents and the ore pulp are fully mixed. The mixed ore pulp after adding the chemicals and mixing is sent into the standing aeration separation area 2 through the mixed ore pulp inlet 8 by the lifting pump 15, in the standing aeration separation area 2, the ore pulp fully reacts with the flotation reagents, and a plurality of bubble generators 14 at the bottom of the standing aeration separation area 2 generate a large amount of micro bubbles, so that the probability that the concentrate particles float to the liquid surface to form concentrate foam can be increased, and the improvement of the grade and the recovery rate of the concentrate is facilitated. The concentrate foam floating to the liquid surface is discharged to the concentrate collecting tank 3 by the slag scraper 16, and the tailings are collected to the tailing pond 4 by the tailing collecting device 17 and separated to the tailing separating tank 5, which are conventional processes and will not be described in detail herein.
In the preparation method of the high-activity high-purity magnesium oxide, the flotation condition in the step (2) is to add a dispersing agent and a collecting agent and adjust the pH value; wherein sodium hexametaphosphate is used as a dispersant, dodecylamine is used as a collector and dilute hydrochloric acid is used as a pH value regulator.
In the preparation method of the high-activity high-purity magnesium oxide, the calcining equipment in the step (3) is a suspension furnace, the operating temperature of the suspension furnace is 1000 ℃, the air flow of the suspension furnace is 800mL/s, and the air pressure of the suspension furnace is 1 MPa; the calcination time in the step (3) is 2.5 h.
In the preparation method of the high-activity high-purity magnesium oxide, the fine grinding equipment in the step (4) is a ball mill, and the rotating speed of the ball mill is 70 r/min; the particle size fraction after the fine grinding in the step (4) is 0.2 μm.
Comparative example 1
Chinese invention patent, application number: 201210573609.9, publication No.: CN103011630B, which discloses a method for producing high-purity magnesium hydroxide and magnesium oxide from low-grade magnesite, as described in example 1, "the method for producing high-purity magnesium hydroxide and magnesium oxide from low-grade magnesite is performed according to the following steps: taking 1000g of magnesite, calcining the magnesite for 3 hours at 950 ℃ in a calcining furnace (the loss on ignition is 47.5%), and recovering carbon dioxide decomposed by calcining; crushing the calcined magnesite light-burned ore, and grinding into light-burned powder of 200-300 meshes; 980ml of water is added into the light calcined powder and stirred evenly to prepare light calcined powder slurry with the concentration of 35 percent, and 2500ml of water is added into 1150g of ammonium chloride and stirred to dissolve the ammonium chloride to prepare 25 percent ammonium chloride solution; reacting the light calcined powder slurry with an ammonium chloride solution in an enamel kettle with stirring and heating, wherein the reaction temperature is 105 ℃, the reaction time is 3 hours, ammonia gas, magnesium chloride and calcium chloride are generated in the reaction process, and the ammonia gas is recovered and condensed into ammonia water; the method comprises the following steps of reacting recycled carbon dioxide, ammonia water and calcium chloride in a stainless steel reaction kettle to generate calcium carbonate, removing the calcium carbonate to obtain a magnesium chloride solution, using the ammonia water and the magnesium chloride solution to generate magnesium hydroxide in the stainless steel reaction kettle with stirring and heating, wherein the reaction temperature is 80 ℃, the reaction and aging time is 1.5h, the ammonia water dosage is excessive by 30%, the generated magnesium hydroxide is washed by hot water at 80 ℃, specifically, three times of in-situ countercurrent washing, one time of slurrying and washing, one time of in-situ washing again, drying the obtained water-containing magnesium hydroxide at 130 ℃ for 3h, and then calcining at 600 ℃ for 2h to obtain the high-purity magnesium oxide.
Comparative example 2
Chinese invention patent, application number: 201711120654.8, publication No.: CN107902925A, which discloses a method for smelting light magnesium oxide by using magnesite, as described in example 1, "the present invention provides a method for smelting light magnesium oxide by using magnesite, comprising the following steps:
(1) putting magnesite as a raw material into a carbonization kiln to be calcined into magnesium oxide;
(2) putting the magnesium oxide on a mill, adding water, and finely grinding until the magnesium oxide is sieved by a 200-mesh sieve, wherein the temperature of the magnesium oxide is between 100 ℃ and 150 ℃;
(3) controlling the temperature of the slurry after the sieve sieving to be 80-90 ℃, continuously stirring and digesting for 1.5-3h, adding a separating agent, stirring and separating calcium and magnesium, performing suction filtration on the slurry to obtain filtrate and precipitate, heating and evaporating the filtrate, and then grinding to obtain calcium chloride; adding water into the precipitate, and mixing the precipitate with pulp, and controlling the temperature to be below 20 ℃;
(4) putting the slurry into a carbonization tower, and feeding carbon dioxide gas in a kiln into the carbonization tower through an air compressor and a pipeline when the slurry is calcined, so that the slurry is carbonized and reduced into magnesium carbonate;
(5) precipitating and filtering the magnesium carbonate, then placing the magnesium carbonate into an acid solution with the concentration of 80-95 ℃, carrying out acidolysis to obtain soluble magnesium hydroxide, then adding an oxidant into the mixed acid solution to react, and oxidizing ferrous in the solution into ferric hydroxide after the reaction;
(6) filtering to remove impurities such as ferric hydroxide, adding soluble magnesium hydroxide into the solution, adding 25-28% ammonia brine, diluting and pyrolyzing for about 1-3 hr, and precipitating with magnesium hydroxide generated in the solution until no reaction occurs in the solution;
(7) the precipitated magnesium hydroxide is subjected to filter pressing and then is put into a furnace with the temperature of 300-400 ℃ for light burning or drying to prepare the light magnesium oxide.
Further, the separating agent is magnesium chloride.
Further, the stirring speed after the addition of the separating agent was 60 r/min.
Furthermore, a smoke dust removal device is arranged in the carbonization kiln.
Further, the magnesite is calcined in the carbonization kiln under the following conditions: gradually heating the carbonization kiln from 200 ℃ to 1000 ℃, preserving heat for 60 minutes, cooling to 200 ℃, and then discharging.
Further, the concentration of the acid solution is 90 °.
Further, the magnesium hydroxide after filter pressing is lightly burned or dried at the temperature of below 350 ℃.
According to the method for smelting light magnesium oxide by using magnesite provided by the embodiment of the invention, high-quality light magnesium oxide' can be obtained.
Comparative example 3
Chinese invention patent, application number: 201710041091.7, publication No.: CN108314334A, which discloses a method for producing high purity magnesium oxide from magnesite, as described in the detailed implementation manner, "the method for producing high purity magnesium oxide from low grade magnesite comprises the following steps:
(1) crushing magnesite to obtain magnesite powder; optionally calcining magnesite powder to obtain low-purity magnesium oxide powder; then reacting magnesite powder and optionally low-purity magnesia powder with hydrochloric acid at 50-100 ℃, wherein the magnesite material is in proper excess and the hydrochloric acid is fully utilized to obtain acid leaching solution;
(2) dropwise adding a proper amount of hydrogen peroxide oxidant into the pickle liquor, fully stirring, standing for 5-60 minutes, then carrying out solid-liquid separation, and obtaining a filter cake which can be used as solid waste residue for landfill treatment or used as a building material after washing to obtain a magnesium chloride solution for later use;
(3) evaporating and concentrating the magnesium chloride solution, and then carrying out spray granulation at the temperature of less than 200 ℃ to produce a low-hydration magnesium chloride material;
(4) feeding the low-hydration magnesium chloride material into a fluidized bed pyrolysis reactor, controlling the retention time of the material in a fluidized bed, and ensuring that the material is completely pyrolyzed at the temperature of 600-800 ℃ to obtain crude magnesium oxide and pyrolysis tail gas;
(5) pyrolysis tail gas flowing out of the fluidized bed pyrolysis reactor contains a large amount of hydrogen chloride components, the hydrogen chloride components are input into an absorption tower and directly absorbed by magnesite powder slurry with the concentration of 1000-;
the crude magnesium oxide is firstly digested by water, wet ball milling treatment can be adopted to ensure that soluble salt components in the crude magnesium oxide are fully dissolved, then solid-liquid separation is carried out, and the obtained solid phase is subjected to three-stage countercurrent water washing to completely remove the soluble salt components in the solid phase; the solid phase obtained after washing is fed into a fluidized bed roasting furnace and roasted at the temperature of 400-800 ℃ to obtain the light-burned magnesium oxide product with high activity, high whiteness and high purity.
Through the processing of the process, the magnesite raw material with low grade and low value can be processed into a high-value high-purity magnesium oxide product.
Comparative example 4
Chinese invention patent, application number: 201911178469.3, publication No.: CN110775992A, which discloses a method for preparing high-purity magnesium oxide by using magnesite purification, as described in example 4, "(1) grinding magnesite into powder by using an ore mill, sieving the powder through a 200-mesh (0.074mm) sieve, and mixing magnesium chloride hexahydrate and magnesite powder according to a mass ratio of 2: 1 proportion, fully mixing and grinding the magnesite and the chlorinating agent, then heating to 650 ℃ at the heating rate of 5 ℃/min and calcining for 1h, wherein the magnesite disappears at 650 ℃ to obtain light-burned magnesium oxide, and the local part of the light-burned magnesium oxide is heterogeneous. (2) Preparing 60g/L of slurry from the calcined product by using deionized water, stirring and digesting for 3 hours at normal temperature, and carrying out suction filtration. The impurities contained in the light-burned magnesium oxide are mainly calcium chloride, magnesium chloride, ferric oxide, silicon oxide and the like. The digestion process is mainly a process of reacting magnesium oxide with water to generate magnesium hydroxide. After the digestion process is finished, the Ca in the light-burned magnesium oxide can be removed by filtering twice2+、Cl-And is redundantMg2+To obtain a filter cake containing magnesium hydroxide and a small amount of insoluble impurities such as Fe, Si and the like. Then the filter cake is re-slurried and is filled with 0.3m3CO of/h2Carrying out carbonization reaction under the stirring condition of 500r/min to obtain Mg (HCO)3)2The heavy magnesium aqueous solution of (1). And insoluble impurities such as Fe, Si and the like in the light calcined magnesia can be removed by filtering twice. (3) Reacting the heavy magnesium aqueous solution obtained under the carbonization process condition for 20min at 95 ℃ after suction filtration, then carrying out suction filtration, and drying the filter cake at 105 ℃ to obtain basic magnesium carbonate serving as a precursor of magnesium oxide; (4) and (3) heating the obtained basic magnesium carbonate to 600 ℃ at the heating rate of 5 ℃/min, and calcining for 2h to finally obtain a high-purity magnesium oxide product.
Comparative example 5
Chinese invention patent, application number: 201810062195.0, publication No.: CN108249786B discloses a method for continuously producing active magnesium oxide and recovering carbon dioxide by heating magnesite with microwaves, as described in example 1, in the specific implementation process, the invention heats magnesite particles with microwaves to produce high-activity magnesium oxide and recovers high-purity CO generated in the production process2The production method is specifically illustrated as follows:
(1) the magnesite particles are filled for the first time and directly enter the exhaust chamber 4, the outlet door 19 of the charging vacuum chamber 3 is closed, the magnesite particles are heated by microwave radiation, and CO discharged from the exhaust chamber 4 after heating2The gas, which is not recycled, is only used to heat the air heat exchanger 8 of the preheating chamber 2 for warming the magnesite particles in the preheating chamber 2.
(2) The magnesite particles with the size smaller than 1mm are loaded into a preheating chamber 2 wrapped by heat-insulating materials by a weighing and distributing bin 1, an inlet door in the preheating chamber 2 is closed, and high-temperature CO discharged by an exhaust chamber 4 is utilized2The gas and the cooled high-temperature gas discharged from the cooling collection chamber 6 pass through an air heat exchanger 8 in the preheating chamber 2 to heat the magnesite particles.
The preheating is realized by detecting the output temperature of the air heat exchanger, the air temperature cooled by the cooling collection chamber and the temperature of magnesite particles in the preheating chamber at different positions in conveying through a temperature sensor and controlling the temperature sensor to heat the magnesite particles step by step through a programmable controller. And (3) gradually heating the magnesite particles in the preheating chamber to 200-300 ℃ so as to gasify and discharge water and part of organic impurities contained in the magnesite particles.
(3) While the magnesite particles in the exhaust chamber 4 enter the discharge vacuum chamber 5, the feed vacuum chamber inlet door 18 of the feed vacuum chamber 3 is opened, the magnesite particles in the preheating chamber 2 are pushed into the feed vacuum chamber 3, then the feed vacuum chamber inlet door 18 in the feed vacuum chamber 3 is closed, and the vacuum pump 9 is started.
(4) And (3) pumping the feeding vacuum chamber 3 to a vacuum degree of 5-15 Pa by a vacuum pump 9 through an air-water heat exchanger 13, and closing the vacuum pump 9.
(5) After the inlet door 20 of the discharging vacuum chamber 5 is closed, the outlet door 19 of the charging vacuum chamber 3 is opened, the magnesite particles in the charging vacuum chamber 3 are pushed into the exhaust chamber 4, the outlet door 19 of the charging vacuum chamber 3 is closed, the microwave source 7 is started to heat the magnesite particles, and at this time, new magnesite particles enter the preheating chamber 2 to be preheated.
(6) When the temperature of the magnesite grains heated by the microwave in the exhaust chamber 4 reaches the decomposition temperature, the exhaust chamber 4 removes high-temperature CO2The gas is connected to an air heat exchanger 8 in the preheating chamber 2 through a pipeline, is cooled through an air-water heat exchanger 13, enters a carbon dioxide collecting system 14, and is sent to a low-pressure gas storage tank through a gas booster pump.
(7) Connecting to compressor of low-pressure gas storage tank, further increasing pressure to 71MPa, weighing, bottling, and adding CO2The volume purity of the gas reaches more than 99 percent.
(8) Heating magnesite particles, controlling intermittent microwave radiation through a PLC (programmable logic controller), starting heating at a preheating temperature a (200-300 ℃ in the embodiment) shown in figure 2, reaching a decomposition temperature b (400 ℃ in the embodiment), continuing heating, finally reaching a set highest temperature c (500-700 ℃ in the embodiment), and keeping at a set temperature d, wherein the magnesite particles continuously decompose CO2Gas until the decomposition process is finished e.
The activity of the magnesium oxide is related to the set maximum temperature c. The temperature rise change is controlled by controlling the microwave radiation energy through the PLC, the lower the highest temperature c is, the longer the heating retention time d is, the lower the productivity is, and the higher the activity degree of the magnesium oxide is. On the contrary, the productivity is high and the activity is low.
Decomposition of CO by magnesite granules2And finishing the gas process to generate active magnesium oxide.
At this time, the electric valve on the connecting pipeline of the vacuum discharging vacuum chamber 5 and the exhaust chamber 4 is opened to make the air pressure of the discharging vacuum chamber 5 and the air pressure of the exhaust chamber 4 the same, the inlet door 20 of the discharging vacuum chamber 5 is opened, the active magnesium oxide is sent into the discharging vacuum chamber 5, the inlet door 20 of the discharging vacuum chamber 5 is closed, and the electric valve on the connecting pipeline of the discharging vacuum chamber 5 and the exhaust chamber 4 is closed.
(9) And opening an outlet door 21 of the discharging vacuum chamber 5 of the discharging vacuum chamber, and sending the active magnesium oxide into the cooling collection chamber 6.
(10) And closing an outlet door 21 of the discharging vacuum chamber 5, and pumping the discharging vacuum chamber 5 to the vacuum degree of 5-15 Pa to prepare for the next process.
(11) The active magnesium oxide in the cooling collection chamber 6 is rapidly cooled by blowing air through an air-blowing cooling system 12. The high-temperature gas used for cooling is cooled through the air heat exchanger 8 of the preheating chamber 2, and the magnesite particles in the preheating chamber 2 are heated.
(12) When the temperature of the cooling air drops below the temperature of the air heat exchanger 8 in the preheating chamber 2, the exhaust to the air heat exchanger 8 is stopped, and the cooling air is exhausted to the outside.
(13) When the activated magnesium oxide is cooled to a temperature at which it can be recovered, bagging operations are immediately performed ".
Example 2
The magnesium oxide prepared in example 2 and the magnesium oxide prepared in comparative examples 1 to 5 were selected and tested with reference to HG/T2573-2012.
TABLE 1 comparison of the test parameters
Compared with comparative examples 1-5, the hair conditionerThe magnesium oxide prepared in the embodiment 1 has good performance advantages, and the test parameters such as the bulk density, the content of active magnesium oxide, the content of calcium oxide, the content of hydrochloric acid insoluble substances, the content of chloride, the ignition loss and the like show significant differences, so that the magnesium oxide is high-quality, high-activity and high-purity magnesium oxide. Specifically, the invention fully utilizes the basic conditions of magnesite tailing flotation purification and novel suspension furnace, and the like applied by the company in the prior art, researches and develops the volume density of 3.35g/cm3The high-purity magnesite replaces fused magnesite, so that the blank of high-end products of magnesite industry in Liaoning areas is filled, and comprehensive development and cyclic utilization of magnesite tailing resources in areas are promoted to take a new step.
Example 3
In combination with the test results of example 2, the magnesium oxide prepared in example 1 was selected for activity, SEM and XRD tests. The specific method refers to the following documents (Pengqiang, Guo Yuxiang, Qu palaili, etc.. suspension state calcining magnesite to prepare high-activity light calcined magnesia [ J ]. refractory material, 2017,51(004): 264-.
As shown in FIGS. 1 and 2, the magnesium oxide prepared by the present invention has small crystal grain size, low crystallinity and large specific surface area. Wherein the activity is measured according to the citric acid method, the activity index is 3.63, and the citric acid color development time is 30 s.
Example 4
After the project is successfully researched and developed, a company can produce 10 million tons of high-activity high-purity magnesium oxide every year, consume 30-40 million tons of low-grade magnesite, and can obtain the economic benefit of 3000-4000 million yuan.
The present invention and its embodiments have been described above schematically, without limitation, and what is shown in the drawings is only one of the embodiments of the present invention, and the actual structure is not limited thereto. Therefore, if the person skilled in the art receives the teaching, without departing from the spirit of the invention, the person skilled in the art shall not inventively design the similar structural modes and embodiments to the technical solution, but shall fall within the scope of the invention.
Claims (7)
1. The preparation method of the high-activity high-purity magnesium oxide is characterized by comprising the following steps of:
(1) cleaning magnesite: taking low-grade magnesite as a raw material, cleaning, and removing mud and micro-fine particle minerals on the surface of the magnesite for later use;
(2) refining magnesite: refining the magnesite cleaned in the step (1), wherein the refining process is divided into six steps, the first step is to crush the magnesite, the second step is to roast the crushed magnesite, the third step is to grind the roasted magnesite, the fourth step is to add water into the grinded magnesite to prepare raw ore pulp, the fifth step is to desliming the raw ore pulp, and the sixth step is to perform flotation on the deslimed raw ore pulp to obtain refined ore powder for later use;
(3) calcining magnesite: calcining the concentrate powder prepared in the step (2) for later use;
(4) fine grinding of magnesite: and (4) fine grinding and activating the calcined concentrate powder in the step (3).
2. The method for preparing high-activity high-purity magnesium oxide according to claim 1,
the mass percentage range of the magnesite in the low-grade magnesite in the step (1) is 30-45%, wherein the mass percentage range of the dolomite is 10-30%, the mass percentage range of the quartz is 5-15%, and the balance is other mineral impurities.
3. The method for preparing high-activity high-purity magnesium oxide according to claim 1,
the size fraction of the crushed magnesite in the step (2) is 5-10 mm;
the roasting equipment in the step (2) is a rotary kiln or a fluidized bed furnace;
the grinding equipment in the step (2) is a ball mill, and the rotating speed of the ball mill is 50 r/min;
the ground particle size in the step (2) is 0.1mm-0.3 mm;
the desliming equipment in the step (2) is a desliming cyclone;
the water content of the concentrate powder in the step (2) is less than 20 percent, and the MgO content is 45 to 50 percent.
4. The method for preparing high-activity high-purity magnesium oxide according to claim 1,
the flotation equipment in the step (2) is a flotation tank, the flotation tank is divided into a dosing reaction zone, a standing aeration separation zone, a concentrate collecting tank, a tailing tank and a tailing collecting tank by a wall plate, the bottom surface of the dosing reaction zone is an inclined plane, one side of the dosing reaction zone, which is close to the standing aeration separation zone, inclines downwards, the top of the dosing reaction zone is provided with an electric stirrer, the lower part of the outer side wall is provided with an ore pulp inlet, the wall plate between the standing aeration separation zone and the dosing reaction zone is provided with a mixed ore pulp inlet, the bottom of the standing aeration separation zone is provided with a bubble generator, one side of the tailing tank is provided with a tailing collecting device, the top of the standing aeration separation zone is communicated with the concentrate collecting tank, the upper part of the communication.
5. The method for preparing high-activity high-purity magnesium oxide according to claim 1,
and (3) adding a dispersing agent and a collecting agent into the flotation conditions in the step (2), and adjusting the pH value.
6. The method for preparing high-activity high-purity magnesium oxide according to claim 1,
the calcining equipment in the step (3) is a suspension furnace, the operating temperature of the suspension furnace is 900-1100 ℃, the air flow of the suspension furnace is 500-1200 mL/s, and the air pressure of the suspension furnace is 1 MPa;
the calcining time in the step (3) is 2h-3 h.
7. The method for preparing high-activity high-purity magnesium oxide according to claim 1,
the fine grinding equipment in the step (4) is a ball mill, and the rotating speed of the ball mill is 70 r/min;
the particle size after the fine grinding in the step (4) is 0.1-0.3 μm.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN113772971A (en) * | 2021-08-20 | 2021-12-10 | 中钢集团鞍山热能研究院有限公司 | Process and system for preparing high-purity magnesium oxide in low-carbon circulation mode |
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| CN104098279A (en) * | 2013-04-12 | 2014-10-15 | 沈阳铝镁设计研究院有限公司 | Low-grade magnesite light burning technology |
| CN104437883A (en) * | 2014-11-13 | 2015-03-25 | 中蓝连海设计研究院 | Digestion-desliming-reverse floatation method for treatment of low-grade magnesite high in silicon content and calcium content |
| CN104511368A (en) * | 2013-09-26 | 2015-04-15 | 沈阳铝镁设计研究院有限公司 | Low-grade magnesite purifying process |
| CN205436031U (en) * | 2015-12-25 | 2016-08-10 | 辽宁东和新材料股份有限公司 | Low -grade floatation device for magnesite |
| CN109206024A (en) * | 2018-11-30 | 2019-01-15 | 嘉晨集团有限公司 | A kind of preparation method producing highly-purity magnesite using low-grade magnesite as raw material |
| CN109809716A (en) * | 2019-03-29 | 2019-05-28 | 东北大学 | Low-grade magnesite calcining decalcification removes the method that silicon prepares high-purity light calcined magnesia |
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| CN104098279A (en) * | 2013-04-12 | 2014-10-15 | 沈阳铝镁设计研究院有限公司 | Low-grade magnesite light burning technology |
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| CN104437883A (en) * | 2014-11-13 | 2015-03-25 | 中蓝连海设计研究院 | Digestion-desliming-reverse floatation method for treatment of low-grade magnesite high in silicon content and calcium content |
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