CN112010337A - Large-size aragonite whisker prepared by carbonizing impurity-containing calcareous raw material and method thereof - Google Patents

Large-size aragonite whisker prepared by carbonizing impurity-containing calcareous raw material and method thereof Download PDF

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CN112010337A
CN112010337A CN202010901685.2A CN202010901685A CN112010337A CN 112010337 A CN112010337 A CN 112010337A CN 202010901685 A CN202010901685 A CN 202010901685A CN 112010337 A CN112010337 A CN 112010337A
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aragonite
gas
refined
stirring
lime milk
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彭同江
孙红娟
罗东山
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Southwest University of Science and Technology
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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
    • C01F11/00—Compounds of calcium, strontium, or barium
    • C01F11/18—Carbonates
    • C01F11/182—Preparation of calcium carbonate by carbonation of aqueous solutions and characterised by an additive other than CaCO3-seeds
    • 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
    • C01F11/00—Compounds of calcium, strontium, or barium
    • C01F11/18—Carbonates
    • C01F11/181—Preparation of calcium carbonate by carbonation of aqueous solutions and characterised by control of the carbonation conditions
    • 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
    • C04B2/02—Lime
    • C04B2/04—Slaking
    • 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
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2002/00—Crystal-structural characteristics
    • 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
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/01—Particle morphology depicted by an image
    • C01P2004/02—Particle morphology depicted by an image obtained by optical microscopy
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/01—Particle morphology depicted by an image
    • C01P2004/03—Particle morphology depicted by an image obtained by SEM
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/10—Particle morphology extending in one dimension, e.g. needle-like
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/80—Compositional purity

Abstract

The invention provides a large-size aragonite whisker prepared by carbonizing an impurity-containing calcareous raw material and a method thereof, wherein the method comprises the following steps: calcining marble particles at high temperature to obtain quick lime and crude CO2A gas; adding water into quicklime for digestion to obtain crude lime milk; removing impurities from the crude lime milk to obtain refined lime milk, adding appropriate amount of crystal form control agent, and adding crude CO2After removing impurities from the gas, intermittently introducing the gas into the refined lime milk, and circulating for multiple times to obtain turbid liquid; filtering the turbid solution, washing, drying and scattering the material to obtain the aragonite crystal whisker with the middle diameter of 3-10 microns and the length of 60-90 microns. The method has the advantages of wide raw material source, high resource utilization rate, simple method, low process cost and easy realization in industry. And the obtained aragonite whisker has large size, high rate of crystal straightening and high resolutionThe powder is uniform.

Description

Large-size aragonite whisker prepared by carbonizing impurity-containing calcareous raw material and method thereof
Technical Field
The invention relates to a method for preparing large-size aragonite whiskers by using impurity-containing calcareous ores or calcareous tailings and tailings as raw materials through calcining, digesting, purifying and intermittent carbonization, and a large-size aragonite whisker product, and belongs to the field of comprehensive utilization of resources and inorganic non-metallic materials.
Background
The aragonite whisker has larger length-diameter ratio, complete structure, less internal defects, high strength and modulus close to those of a complete crystal, high strength and modulus, excellent heat resistance and heat insulation, white powder in appearance and needle or fibrous monocrystal under a microscope. Can be used as a reinforcing material to be widely applied to the industries of plastics, rubber, medicine, paper making and the like.
At present, the preparation method of aragonite whisker mainly comprises a double decomposition reaction method, a urea hydrolysis method, a calcium bicarbonate heating decomposition method, a carbonization method and the like. The double decomposition reaction method is to utilize soluble calcium salt and soluble carbonate solution to generate CaCO through double decomposition reaction under certain conditions3The whisker method has the defects of low reactant concentration, slow reaction speed and low product yield. The urea hydrolysis method utilizes CO generated by urea hydrolysis2Preparation of CaCO by reaction with solutions containing calcium ions3The method has simple reaction mechanism, but needs reaction at high temperature and high pressure, has high energy consumption and has great potential safety hazard. The calcium bicarbonate thermal decomposition method is a method for obtaining aragonite whiskers by heating a supersaturated solution of calcium bicarbonate to decompose it. The aragonite whisker obtained by the method has larger length and higher length-diameter ratio, but the reaction condition needs to be strictly controlled, the reaction speed is slow, and the production efficiency is lower.
Chinese patent application publication No. CN109704382A, 5/3/2019, discloses a method for preparing calcium carbonate whiskers, which mainly uses polyethylene glycol as a regulator and adopts a carbonization method to prepare calcium carbonate whiskers. The film technology adopted for recovering the carbon dioxide gas in the method is easy to cause film blockage due to the action of impurity particles in actual production, so that the normal recovery of the gas is influenced, and the film replacement cost is high; in addition, large-sized whiskers were not obtained.
Chinese patent application publication No. CN1552959A, 12/8/2004, discloses a process for preparing calcium carbonate whiskers. The process adopts quicklime as a reaction raw material, and the obtained aragonite whisker has a small length of 7-25 mu m.
Chinese patent application with publication number CN110029396A, 3/6/2019, discloses a preparation method of functional calcium carbonate whiskers, which comprises the steps of adding calcium hydroxide suspension into a supergravity reactor, taking phosphoric acid as a crystal form control agent, and controlling the rotating speed to be 1000 r/min-1800 r/min in the reaction process. The shape of the obtained aragonite whisker is mostly cluster-shaped and dendritic-shaped, the crystal straightening rate is low, and the crystal dispersibility is not high under the conditions of a supergravity reactor and high rotating speed.
Chinese patent application publication No. CN109467112A discloses an aragonite type seed crystal, aragonite type light calcium carbonate and a preparation method thereof, wherein the method needs to obtain aragonite type calcium carbonate through secondary carbonization, the aragonite type calcium carbonate seed crystal is obtained through carbonization, then the seed crystal is ground and added into a reaction system to react again to induce calcium hydroxide slurry to form aragonite type light calcium carbonate, the process is complex, the period is long, and the obtained aragonite crystal whisker is short and only about 25 μm in length.
In journal article 'preparation of aragonite whiskers by a marble tailing carbonization method and morphological analysis thereof' (Rodongshan and the like, mineral product protection and utilization, 8 months in 2019, 4 th stage, 60-65 pages), marble tailings are used as raw materials, and after calcination treatment, the aragonite whiskers are prepared by a carbonization method, wherein the length of the obtained whiskers is 40-55 microns, the diameter is 5-8 microns, the length-diameter ratio is 13-18, and the length of the obtained whiskers is not large and is not more than 55 microns.
In journal article "preparation of calcium carbonate whisker by using magnesium chloride as crystal form control agent" (Lezhen et al, silicate science and newspaper, 9.2005, volume 33, phase 9, page 1153-1156), a calcium carbonate crystal seed is prepared first, and then the calcium carbonate whisker is prepared by secondary carbonization, the adopted process is complex, the reaction period is long, and the average length of the obtained whisker is only about 35 μm.
In conclusion, the existing production process only uses high-purity lime raw materials, does not use low-purity lime or tailing slag and the like as raw materials, and has the problems of complex process, long period, high production cost, large energy consumption of reaction conditions, and short length and small size of the obtained crystal whisker.
Disclosure of Invention
The present invention aims to address at least one of the above-mentioned deficiencies of the prior art.
In order to solve the problems in the prior art, the invention aims to provide a preparation method of large-size (for example, the length of the crystal whisker is not less than 60 mu m) aragonite crystal whisker, which has the advantages of wide raw material source, high resource utilization rate, low production cost, simple process and easy realization of industrial application.
In order to achieve the above object, another aspect of the present invention provides a method for preparing large-sized aragonite whiskers by batch carbonization of a calcareous raw material containing impurities, the method comprising the steps of: crushing and grading the limestone raw material, and then calcining at high temperature to obtain impurity-containing quicklime and rough CO2A gas; adding water to carry out a digestion reaction on the impurity-containing quicklime, then aging to obtain rough lime milk, adding water into the rough lime milk, stirring, and removing impurities to obtain refined lime milk; for the crude CO2Removing impurities from the gas to obtain refined CO2A gas; pumping the refined lime milk into a carbonization reaction tank with high-speed stirring and heating functions and a gas conduit, adding a magnesium salt crystal form control agent containing magnesium ions, uniformly stirring, heating to a reaction temperature, and introducing the refined CO2Performing carbonization reaction on gas to obtain suspension, and filtering, washing, drying and dispersing the suspension to obtain the large-size aragonite whisker, wherein the step of obtaining the suspension is to perform more than two times of ventilation stirring procedures in sequence under the condition that the addition amount of the magnesium salt crystal form control agent can ensure that the concentration of magnesium ions in the solution reaches 0.2-0.6 mol/L and the reaction temperature is 70-90 ℃, and the ventilation stirring procedures are to introduce the refined CO at the speed of 30-60L/min-kgCaO while stirring2Stopping introducing refined CO immediately after 20-40 min2And continuously stirring for 10-20 min.
In another aspect of the invention, the large-size aragonite whisker is prepared by the method. The aragonite whisker has aragonite phase, toothpick shape, aragonite content over 80%, middle diameter of 3-10 microns and length of 60-90 microns.
Compared with the prior art, the invention has the beneficial effects that: the method can provide the method for preparing the aragonite whiskers by using raw marble and limestone ore or tailing residues of tailings as raw materials, carrying out processes such as calcination, digestion, impurity removal and the like, purifying and then carbonizing recycled calcination kiln gas, and adopting an intermittent aeration method, so that the method can realize recycling of resources and reduce the process cost, and the obtained aragonite whiskers have large length and diameter (for example, the length is 60-90 mu m, and the diameter of the middle parts of the whiskers is 3-10 mu m).
Drawings
Fig. 1 shows a production process flow diagram of an exemplary embodiment of the method of the present invention.
FIG. 2 shows X-ray diffraction patterns of aragonite whiskers in example 1(Ar-1), example 2(Ar-2), example 3(Ar-3), and example 4 (Ar-4).
FIGS. 3A and 3B show scanning electron micrographs of aragonite whiskers (Ar-1) from example 1.
Fig. 4A and 4B show optical microscope images of the aragonite whisker (Ar-2) of example 2.
Fig. 5A and 5B show optical microscope images of the aragonite whisker (Ar-3) of example 3.
Fig. 6A and 6B show optical microscope images of the aragonite whisker (Ar-4) of example 4.
Detailed Description
Hereinafter, the large-sized aragonite whiskers prepared by carbonizing an impurity-containing calcareous raw material and the method thereof according to the present invention will be described in detail with reference to the exemplary embodiments.
Fig. 1 shows a production process flow diagram of an exemplary embodiment of the method of the present invention.
As shown in fig. 1, in the present exemplary embodiment, the method for preparing large-sized aragonite whiskers by batch carbonization of a calcareous raw material containing impurities is implemented by the following steps:
(1) obtaining impurity-containing quicklime and crude CO2Gas (es)
Specifically, after the limestone raw material is crushed and classified, the raw material is calcined at high temperature to obtain impurity-containing quicklime and crude CO2A gas. Here, the limestone base material may be one or more selected from limestone containing quartz and/or mica as impurities, marble raw ore, and tailings or tailings generated during mining and processing of a limestone mine or marble mine, and CaCO in the limestone base material3The content is 70-99%. For example, CaCO in limestone base3The content can also be 72-79%. The high-temperature calcining device can be any one of a box type, a tube type, a tunnel type electric heating furnace or a rotary kiln.
(2) Obtaining refined lime milk and refined CO2Gas (es)
Specifically, the method comprises the steps of carrying out a digestion reaction on impurity-containing quicklime by adding water, then aging to obtain crude lime milk, and then adding water into the crude lime milk, stirring, removing impurities or purifying to obtain refined lime milk. Wherein the water for the digestion reaction can be industrial water, the water for the digestion reaction can be water demand with the solid-to-liquid ratio of 1: 3-1: 10, the mixture is stirred and digested for 10 min-20 min, the mixture is aged for 1 h-12 h, and then a proper amount of industrial water is added until the obtained rough lime milk is Ca (OH)2The amount concentration of the substance (b) is 0.1mol/L to 0.4 mol/L. In addition, the impurity removal in the step of obtaining the refined lime milk can be performed by separating and removing insoluble solid impurities (for example, quartz, mica, and the like) in the crude lime milk after stirring with water by using a cyclone classifier and/or a filter press.
For crude CO2Removing impurities from the gas to obtain refined CO2A gas. For example, crude CO2The gas impurity removal can be carried out by a bag filter and a device filled with saturated sodium bicarbonate solution2Solid particles and SO in2Etc. to obtain refined CO2A gas.
Here, the sub-step of purifying lime milk and the purified CO are2The gas sub-processes may not be sequentialSimultaneously; or may be performed sequentially.
(3) Carrying out intermittent carbonization reaction to obtain suspension
Specifically, pumping refined lime milk into a carbonization reaction tank with high-speed stirring and heating functions and a gas conduit, adding a magnesium salt crystal form control agent containing magnesium ions and enabling the concentration of the magnesium ions in a carbonization reaction system to reach 0.2-0.6 mol/L, uniformly stirring, heating to the reaction temperature of 70-90 ℃, and introducing refined CO at the speed of 30-60L/min kgCaO while stirring2Gas is fed for 20-40 min, and then refined CO is stopped to be fed immediately2Gas is added and the stirring is continued for 10min to 20 min; and (3) circularly performing the processes of stirring while ventilating and stopping ventilating and continuing stirring for at least 2-3 times under the same condition, and finishing when the pH value of the carbonization reaction system reaches 6.25-6.75 to obtain the suspension.
For example, the magnesium salt crystal form control agent may be one or more selected from magnesium bicarbonate, activated magnesium oxide, magnesium chloride hexahydrate, and anhydrous magnesium chloride. Further, the target temperature for heating may be 78 to 84 ℃. The aeration rate may be 40L/min kgCaO to 50L/min kgCaO. The concentration of magnesium ions may be 0.35mol/L to 0.45 mol/L.
(4) Obtaining large-size aragonite whiskers
And (4) filtering, washing, drying and dispersing the suspension obtained in the step (3) to obtain the large-size aragonite whisker. For example, the phase of the aragonite whisker is aragonite, the morphology is toothpick-shaped, the content of the aragonite reaches more than 80 percent, the diameter of the middle part of the whisker is 3 to 10 mu m, and the length of the whisker is 60 to 90 mu m. For example, a filter press with a washing function can be used for filtering the suspension, and the suspension is washed 2-3 times with industrial water. The drying may be drying the filtered and washed material at 50-300 deg.c in an industrial drier until the water content is lower than 1.5%. The dispersion may be to disperse the dried material into powder by a scattering machine.
In addition, as shown in fig. 1, the method of the present exemplary embodiment may further include a step of adding a filtrate obtained by filtering the suspension to the carbonation reaction tank to recycle the filtrate.
In another exemplary embodiment of the present invention, the method for preparing large-sized aragonite whiskers by batch carbonization of a calcareous raw material containing impurities can also be realized by the following steps:
1) limestone material containing impurities such as quartz and mica, and CaCO thereof3The content is 70-100%, through crushing, grading and calcining in high temperature calcining device at 1000-1100 deg.c for certain time, impurity-containing calcium lime and coarse CO are obtained2A gas.
2) Adding industrial water into the impurity-containing quicklime according to the solid-to-liquid ratio of 1: 3-1: 10, stirring and digesting for 10-20 min, aging for 1-12 h after the digestion reaction is finished, adding the industrial water, and uniformly stirring until the obtained rough lime milk is Ca (OH)2The amount concentration of the substance (b) is 0.1mol/L to 0.4 mol/L.
3) Removing impurities from crude lime milk by cyclone classifier and/or filter press to obtain Ca (OH)2The amount concentration of the substances is 0.1 mol/L-0.4 mol/L; crude CO2The gas is passed through a bag filter and a device containing saturated sodium bicarbonate solution to remove solid particles and SO therefrom2The impurities are equal to obtain refined CO2A gas.
4) Pumping the refined lime milk into a carbonization reaction tank with high-speed stirring and heating functions and a gas conduit, adding a magnesium salt crystal form control agent, uniformly stirring, wherein the crystal form control agent is one of magnesium bicarbonate, active magnesium oxide, magnesium chloride hexahydrate, anhydrous magnesium chloride and the like, and the adding amount is that the concentration of magnesium ions in the solution reaches 0.2-0.6 mol/L; heating the solution to 70-90 ℃ and introducing refined CO2Carbonizing the gas at a ventilation speed of 30-60L/min-kgCaO; the carbonization process adopts an intermittent carbonization mode, specifically, refined CO is introduced in the stirring process2Stopping introducing the gas after the gas is carbonized for 20-40 min, continuously stirring for 10-20 min, and introducing refined CO2Circulating the gas for 2-3 times; stopping reaction when pH value of the solution is 6.5, filtering the suspension with filter press having washing function, washing with water for 3 times, and standingDrying in a drier at 50-300 deg.C until the water content of the material is lower than 1.5%. And scattering the materials by a scattering machine to obtain the large-size aragonite whisker.
The technical solution of the present invention is further explained by detailed examples below.
Example 1
The specific preparation method of this example is as follows:
1) crushing marble ore containing quartz, mica, etc. in Sichuan asbestos county into particles of less than or equal to 3cm, CaCO3Calcining at 1100 deg.C for 30min in a box-type electric heating furnace to obtain calcined lime and crude CO2A gas.
2) Taking a certain amount of quicklime, adding a proper amount of industrial water according to the solid-to-liquid ratio of 1:5, stirring and digesting for 10min to obtain lime milk, aging for 1-12 h, and then continuously adding a proper amount of industrial water to obtain crude lime milk Ca (OH)2The amount concentration of the substances is 0.27mol/L, and insoluble solid impurities such as quartz, mica and the like in the crude lime milk are separated by a cyclone classifier to obtain refined lime milk. Crude CO2Removing impurities from the gas by a bag type dust collector and a device filled with saturated sodium bicarbonate solution to obtain refined CO2A gas.
3) Pumping the refined lime milk into a carbonization reaction tank with high-speed stirring and heating functions and a gas conduit, and weighing a certain amount of industrial magnesium chloride (MgCl)2·6H2O), adding the mixture into a reaction tank to ensure that the concentration of magnesium ions in the emulsion is 0.4mol/L, continuously stirring the emulsion at the speed of 160r/min, introducing refined CO into the emulsion at the speed of 50L/min-kgCaO when the temperature of the emulsion is increased to 90 DEG, and then adding the refined CO into the emulsion2And (3) introducing gas for 30min, stopping introducing gas for 10min while continuously stirring, and circularly introducing gas and stopping introducing gas for 2 times until the pH value is 6.5, and stopping the reaction.
4) And filtering the suspension formed by the reaction by using a filter press with a washing function, washing the material for 3 times by using industrial water, drying the material by using an industrial drying machine at 55 ℃ until the water content is lower than 1.5%, and scattering the material by using a scattering machine to obtain the large-size aragonite whisker (the number is Ar-1).
Example 2
The specific preparation method of this example is as follows:
1) sorting marble tailings of Sichuan asbestos, and crushing into small particles with the particle size of less than or equal to 3mm, wherein CaCO is used as the raw material3The content of 95.81% is calcined in a rotary kiln at 1100 deg.C for 12min to obtain quick lime and crude CO2A gas.
2) Taking a certain amount of quicklime, adding a proper amount of industrial water according to the solid-to-liquid ratio of 1:4, stirring and digesting for 10min, aging for 1-12 h, and then continuously adding a proper amount of industrial water until the obtained crude lime milk is Ca (OH)2The amount concentration of the substances is 0.18mol/L, and insoluble solid impurities such as quartz, mica and the like in the crude lime milk are separated by filtering through a filter press to obtain refined lime milk. Crude CO2Removing impurities from the gas by a bag type dust collector and a device filled with saturated sodium bicarbonate solution to obtain refined CO2A gas.
3) Pumping the refined lime milk into a carbonization reaction tank with high-speed stirring, heating function and gas conduit, and weighing a certain amount of industrial anhydrous magnesium chloride (MgCl)2) Adding into a reaction tank to make the concentration of magnesium ions in the emulsion be 0.5mol/L, stirring the solution at a rotation speed of 200r/min, heating the solution to 85 ℃, and introducing refined CO into the solution at a speed of 40L/min-kgCaO2And (3) stopping gas introduction for 20min while continuously stirring after the gas is introduced for 40min every time, and stopping reaction when the gas is introduced circularly and the gas introduction is stopped for 2 times until the pH value of the solution is 6.5.
4) And filtering the suspension formed by the reaction by using a filter press with a flushing function, flushing the material for 3 times by using industrial water, drying the material in an industrial drying machine at 65 ℃ until the water content is lower than 1.5%, and scattering the material by using a scattering machine to obtain the large-size aragonite whisker (the number is Ar-2).
Example 3
The specific preparation method of this example is as follows:
1) sorting limestone tailings samples of Sichuan river oil market, and crushing the limestone tailings samples into small particles of 0.9-3 mm, wherein CaCO is used as the small particles3The content of 80.72% is calcined in a high temperature furnace at 1100 ℃ for 10min to obtain quick lime and crude CO2A gas.
2) Taking a certain amount of quicklime, adding the quicklime into the mixture according to the solid-to-liquid ratio of 1:4Measuring industrial water, stirring and digesting for 10min, aging for 1-12 h, and then continuously adding a proper amount of industrial water to obtain crude lime milk Ca (OH)2The mass concentration of the substances is 0.2mol/L, and insoluble solid impurities in the crude lime milk are separated by a cyclone classifier to obtain refined lime milk. Crude CO2Removing impurities from the gas by a bag type dust collector and a device filled with saturated sodium bicarbonate solution to obtain refined CO2A gas.
3) Pumping the refined lime milk into a carbonization reaction tank with high-speed stirring, heating function and gas conduit, and weighing a certain amount of industrial magnesium bicarbonate (Mg (HCO)3)2) Adding into a reaction tank to make the concentration of magnesium ions in the emulsion reach 0.6mol/L, stirring the emulsion at the speed of 180r/min, introducing refined CO into the emulsion at a certain speed according to 30L/min-kgCaO when the temperature of the emulsion rises to 80 DEG, and then adding into a reaction tank to obtain the final product2And (3) introducing gas for 40min, stopping introducing gas for 10min while continuously stirring, and circularly introducing gas and stopping introducing gas for 2 times until the pH value is 6.5, and stopping the reaction.
4) And filtering the suspension formed by the reaction by using a filter press with a flushing function, flushing the material for 3 times by using industrial water, drying the material in an industrial dryer at 65 ℃ until the water content is lower than 1.5%, and scattering the material by using a scattering machine to obtain the large-size aragonite whisker (the number is Ar-3).
Example 4
The specific preparation method of this example is as follows:
1) crushing the limestone ore containing impurities in the Sichuan JiangYOU city into 2-3 cm particles, namely CaCO3Calcining at 1100 deg.C for 30min to obtain quicklime and crude CO2A gas.
2) Taking a certain amount of quicklime, adding a proper amount of industrial water according to the solid-to-liquid ratio of 1:7, stirring and digesting for 10min, aging for 1-12 h, and then continuously adding a proper amount of industrial water until the obtained crude lime milk is Ca (OH)2The mass concentration of the substances is 0.24mol/L, and insoluble solid impurities in the crude lime milk are separated by a cyclone classifier to obtain refined lime milk. Crude CO2Removing impurities from gas by bag-type dust collector and device filled with saturated sodium bicarbonate solution to obtain fine powderProduction of CO2A gas.
3) Pumping refined lime milk into carbonization reaction tank with high-speed stirring, heating function and gas conduit, weighing a certain amount of industrial magnesium oxide (MgO), adding into the reaction tank to make the concentration of magnesium ions in the emulsion be 0.3mol/L, stirring the emulsion at 180r/min, introducing refined CO at 40L/min-kgCaO when the temperature of the emulsion is raised to 85 deg.C2And (3) introducing gas for 30min every time, stopping introducing gas for 15min while continuously stirring, and circularly introducing gas and stopping introducing gas for 3 times until the pH value is 6.5, and stopping the reaction.
4) And filtering the suspension formed by the reaction by using a filter press with a flushing function, flushing the material for 3 times by using industrial water, drying the material in an industrial dryer at 65 ℃ until the water content is lower than 1.5%, and scattering the material by using a scattering machine to obtain the large-size aragonite whisker (the number is Ar-4).
FIG. 2 is an X-ray diffraction pattern of the dried aragonite whisker samples of examples 1-4. In fig. 2, a represents an X-ray diffraction peak of aragonite, B represents an X-ray diffraction peak of brucite, and C represents an X-ray diffraction peak of calcite. In addition to aragonite, each sample also contains a small amount of calcite, the aragonite crystal has good crystallinity, and the quantitative analysis in X' Pert HighScore Plus analysis software obtains products with 93 percent of the content of the aragonite, 3 percent of the content of the calcite and 4 percent of the content of the brucite. The Ar-2 Chinese stone content is 92%, the calcite content is 4%, and the brucite content is 4%. The Ar-3 Chinese stone content is 90%, the calcite content is 4%, and the brucite content is 6%. Ar-4 contains 86% of Chinese stone, 4% of calcite and 10% of brucite.
FIGS. 3A and 3B are scanning electron micrographs of the Ar-1 aragonite whiskers, with whiskers having a length of about 65 μm, a diameter of about 5 μm, and an aspect ratio of 13. The relevant sem parameters in fig. 3A are: EHT 20.00kV, Signal a SE1, WD 7.5mm, Mag 500X; the relevant sem parameters in fig. 3B are: EHT 20.00kV, Signal a SE1, WD 7.5mm, Mag 5.00 KX. FIGS. 4A and 4B are electron micrographs of Ar-2 aragonite whiskers, with whiskers ranging from 75 to 85 microns in length, 8 to 10 microns in diameter, and 6 to 9 in aspect ratio.
FIGS. 5A and 5B are electron micrographs of numbered Ar-3 aragonite whiskers, with whiskers ranging from 80 to 90 μm in length, 7 to 9 μm in diameter, and 8 to 12 in aspect ratio. FIGS. 6A and 6B are electron micrographs of Ar-4 aragonite whiskers, with whiskers ranging from 65 μm to 80 μm in length, 6 μm to 8 μm in diameter, and 8-10 in aspect ratio. The obtained crystal whiskers have large size, uniform distribution, smooth surface and high crystal straightening rate.
In conclusion, the invention can prepare the large-size aragonite whisker, and has the beneficial effects that: 1) the method takes the limestone or marble containing impurities and the calcareous tailing tailings as raw materials, and realizes the utilization of low-grade resources and solid waste residues; 2) the flue gas generated in the calcining process is purified and then used as CO for carbonization2The gas can not only reduce the emission of greenhouse gas, but also save the cost of raw materials; 3) by introducing CO intermittently during the carbonization process2The gas technical scheme can obtain large-size aragonite whiskers, and the process is simple and convenient; 4) the solution filtered in the method can be recycled, the cycle times are more than 4, and the process cost can be reduced; 5) the aragonite whisker prepared by the method has the advantages that the diameter of the middle part can reach 3-8 mu m, the length can reach 60-90 mu m, and the size of the whisker is larger.
Although the present invention has been described above in connection with the exemplary embodiments and the accompanying drawings, it will be apparent to those of ordinary skill in the art that various modifications may be made to the above-described embodiments without departing from the spirit and scope of the claims.

Claims (10)

1. A method for preparing large-size aragonite whiskers by batch carbonization of a calcareous raw material containing impurities is characterized by comprising the following steps:
crushing and grading the limestone raw material, and then calcining at high temperature to obtain impurity-containing quicklime and rough CO2A gas;
adding water to carry out a digestion reaction on the impurity-containing quicklime, then aging to obtain rough lime milk, adding water into the rough lime milk, stirring, and removing impurities to obtain refined lime milk; for the crude CO2Removing impurities from the gas to obtain refined CO2Gas (es)；
Pumping the refined lime milk into a carbonization reaction tank with high-speed stirring and heating functions and a gas conduit, adding a magnesium salt crystal form control agent containing magnesium ions, uniformly stirring, heating to a reaction temperature, and introducing the refined CO2Carbonizing the gas to obtain a suspension, filtering, washing, drying and dispersing the suspension to obtain the large-size aragonite whisker,
wherein the step of obtaining the suspension liquid is to perform more than two times of ventilation stirring procedures in sequence under the condition that the addition amount of the magnesium salt crystal form control agent can ensure that the concentration of magnesium ions in the solution reaches 0.2-0.6 mol/L and the reaction temperature is 70-90 ℃, and the ventilation stirring procedures are to introduce the refined CO at the speed of 30-60L/min-kgCaO while stirring2Stopping introducing refined CO immediately after 20-40 min2And continuously stirring for 10-20 min.
2. The method according to claim 1, wherein the reaction temperature is 78 ℃ to 84 ℃ and the velocity is 40L/min-kgCaO to 50L/min-kgCaO.
3. The method according to claim 1, wherein the magnesium ion concentration is 0.35 to 0.45 mol/L.
4. The method according to claim 1, wherein the aeration-stirring step is performed two or more times in this order under the condition that the pH of the carbonization reaction system is 6.25 to 6.75.
5. The method as claimed in claim 1, wherein the limestone base material is one or more selected from limestone containing quartz and/or mica as impurities, marble ore, and tailings or tailings generated during mining and processing of a limestone mine or a marble mine, and CaCO in the limestone base material3The content is 70-99%.
6. The method according to claim 1, wherein the water is added in the digestion reaction in an amount that the solid-to-liquid ratio is 1: 3-1: 10, and the crude milk contains Ca (OH)2The amount concentration of the substance (b) is 0.1mol/L to 0.4 mol/L.
7. The method according to claim 1, wherein the impurity removal in the step of obtaining the refined lime milk is to separate and remove insoluble solid impurities in the crude lime milk after stirring with water by a cyclone classifier and/or a filter press.
8. The method of claim 1, wherein the obtaining refined CO is performed by2The impurity removal in the gas step is carried out by passing the crude CO through a bag filter and a device containing saturated sodium bicarbonate solution2Solid particles and SO in2And (4) removing.
9. A large-sized aragonite whisker, characterized in that it is prepared by the method of any one of claims 1 to 8.
10. The large-size aragonite whisker according to claim 1, wherein the aragonite whisker has an aragonite phase, a toothpick shape, an aragonite content of more than 80%, a diameter of 3 μm to 10 μm in the middle of the whisker, and a length of 60 μm to 90 μm.
CN202010901685.2A 2020-08-31 2020-08-31 Large-size aragonite whisker prepared by carbonizing impurity-containing calcareous raw material and method thereof Pending CN112010337A (en)

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Application publication date: 20201201