CN113998905A - Dolomite calcined dolomite digestion separation method and device - Google Patents

Dolomite calcined dolomite digestion separation method and device Download PDF

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CN113998905A
CN113998905A CN202111595132.XA CN202111595132A CN113998905A CN 113998905 A CN113998905 A CN 113998905A CN 202111595132 A CN202111595132 A CN 202111595132A CN 113998905 A CN113998905 A CN 113998905A
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pipe
gas
dolomite
digestion
calcined dolomite
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CN113998905B (en
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王庆伟
柴立元
陶柏润
李青竹
闵小波
史美清
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Central South University
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Central South University
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Priority to PCT/CN2022/086671 priority patent/WO2023115759A1/en
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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
    • C04B2/02—Lime
    • C04B2/04—Slaking
    • C04B2/08—Devices therefor
    • 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
    • C01F11/183—Preparation of calcium carbonate by carbonation of aqueous solutions and characterised by an additive other than CaCO3-seeds the additive being an organic compound
    • 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
    • C01F5/24—Magnesium carbonates
    • 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
    • C04B2/045—After-treatment of slaked lime
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/141—Feedstock

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Ceramic Engineering (AREA)
  • Materials Engineering (AREA)
  • Structural Engineering (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Geology (AREA)
  • Inorganic Chemistry (AREA)
  • Health & Medical Sciences (AREA)
  • General Health & Medical Sciences (AREA)
  • Processing Of Solid Wastes (AREA)

Abstract

The invention provides a dolomite calcined dolomite digestion separation method and a device, wherein the method comprises the following steps: s1, digesting the first calcined dolomite with water to obtain a digestive emulsion; s2, adding an inhibitor into the digestive emulsion; s3, passing the digestive emulsion added with the inhibitor through the feed opening, and sending carbon dioxide with pressure into a separation device through the gas injection pipe for carbonization reaction; s4, when the pH value of the carbonized slurry in the carbonization reaction tank is 7.0-7.8, taking out the carbonized slurry and carrying out solid-liquid separation to obtain calcium carbonate precipitate and magnesium bicarbonate solution. The invention can complete the treatment of the dolomite calcined dolomite with lower cost, so that the calcium and the magnesium are separated more thoroughly, and the improved process is simpler and more convenient to operate.

Description

Dolomite calcined dolomite digestion separation method and device
Technical Field
The invention relates to deep processing of dolomite calcined dolomite, in particular to a dolomite calcined dolomite digestion and separation device and a treatment method.
Background
In order to complete the separation of calcium and magnesium in dolomite, the current main method is as follows: after the dolomite calcined dolomite is digested, the generated digestive emulsion is utilized to carry out calcium-magnesium separation. Wherein calcium and magnesium are mainly separated from dolomite industrially by a carbonization method, the main action object of the dolomite carbonization method is digestive emulsion of the dolomite, the dolomite is calcined at 950-1200 ℃ to prepare calcined dolomite containing magnesium oxide and calcium oxide, the calcined dolomite is added with water to digest and remove slag to be refined into slurry to obtain the digestive emulsion, and the digestive emulsion mainly comprises Ca (OH)2And Mg (OH)2. In the carbonization process, the digestive emulsion is usually carbonized with carbon dioxide gas in a carbonization tower, thereby Ca (OH)2Conversion to CaCO3，Mg(OH)2Conversion to Mg (HCO)3)2. After carbonization is finished, filtering the carbonized slurry to obtain filter residue which is magnesium-containing calcium carbonate, pyrolyzing the filter liquor to obtain light magnesium carbonate, and pyrolyzing and calcining the light magnesium carbonate to obtain magnesium oxide.
The existing carbonization equipment usually adopts a tower structure, and can separate calcium and magnesium, but in the carbonization process, the carbonization reaction is a gas-liquid-solid three-phase reaction, the process is complex, the utilization rate of carbon dioxide is low, the calcium and magnesium separation is incomplete, and the control difficulty of the reaction process is high.
In order to solve the above problems, chinese patent publication No. CN103183369B discloses a device and a method for continuously carbonizing calcium and magnesium in a pipeline, which can improve carbonization efficiency by contacting gas and slurry through local high-speed turbulence, but the tubular structure adopted by the device is transversely arranged, which cannot form a spraying effect, and cannot instantaneously and rapidly improve the contact frequency of carbon dioxide and slurry, and because the device does not cut carbon dioxide in advance, the contact surface and the contact frequency of carbon dioxide and slurry are greatly reduced, and calcium and magnesium are not completely separated.
In addition, the researchers research the technology of extracting magnesium oxide by a pressure carbonization method on the basis of a carbonization tower, and the pressure carbonization method can increase the solubility of carbon dioxide, increase the content of magnesium bicarbonate in a liquid phase, and improve the carbonization efficiency and the utilization rate of carbon dioxide. However, the pressure carbonization method has large requirements on equipment, increases power energy consumption, and is difficult to popularize because the calcium-magnesium separation efficiency is unstable. Still another scholars have studied the continuous spray and bubbling and combined ordinary pressure two times of carbonization processes, the two times of carbonization is to get the calcium-containing magnesium carbonate to carbonize the calcium-containing heavy magnesium water after the first carbonization and carry on the second carbonization to get the calcium in the calcium-containing magnesium carbonate and precipitate, prepare the high-purity magnesium oxide, however, the two times of carbonization processes make the production flow lengthen, the energy consumption increases, and the carbonization apparatus is put into higher costs.
In view of the above, there is a need for a dolomite calcined dolomite digestion separation method and apparatus, which can solve or at least alleviate the above technical disadvantages of incomplete separation and high cost.
Disclosure of Invention
The invention mainly aims to provide a dolomite calcined dolomite digestion separation device and a dolomite calcined dolomite digestion separation method, and aims to solve the technical problems of incomplete separation and high cost in the prior art.
In order to realize the aim, the invention provides a dolomite calcined dolomite digestion and separation device, which comprises a carbonization reaction tank, a gas-liquid mixing reactor and a circulating pump; wherein the content of the first and second substances,
the top of the carbonization reaction tank is provided with a feed inlet and an air path circulating outlet for calcined dolomite digestion liquid to enter, and the bottom of the carbonization reaction tank is provided with an air path circulating outlet and a drainage valve;
the gas-liquid mixing reactor comprises a gas-liquid mixing pipe, a feeding pipe, a gas spraying pipe and a convection mixing injection pipe; the feed inlet of the feed pipe is positioned outside the carbonization reaction tank, and the outlet end of the feed pipe is inserted into the gas-liquid mixing pipe from the top of the gas-liquid mixing pipe; the gas-liquid mixing pipe is arranged inside the carbonization reaction tank, the joint of the gas-liquid mixing pipe and the feeding pipe is sealed by a sealing element, and the side wall of the gas-liquid mixing pipe is also provided with a gas inlet(ii) a The gas inlet end of the gas injection pipe is simultaneously connected with CO2The pressure gas supply device is communicated with the gas circuit circulating outlet, and the exhaust end of the gas ejector pipe is fixedly installed with the gas inlet; the vertical position of the discharge hole of the feeding pipe is lower than that of the air inlet;
the convection mixing and spraying pipe is arranged below the gas-liquid mixing pipe, the outlet of the gas-liquid mixing pipe is vertically communicated with the carbonization reaction tank, and the convection mixing and spraying pipe is sequentially provided with a forward flow mixer and a reverse flow mixer from top to bottom;
the forward flow mixer comprises a first pipe body and a first spiral bulge convexly arranged on the inner wall of a pipe cavity of the first pipe body, the backward flow mixer comprises a second pipe body and a second spiral bulge convexly arranged on the inner wall of a pipe cavity of the second pipe body, and the spiral directions of the first spiral bulge and the second spiral bulge are opposite;
the inlet of circulating pump with water route circulation export intercommunication, the liquid outlet of circulating pump with the feed inlet intercommunication of inlet pipe.
Further, the first spiral protrusion and the second spiral protrusion are both of a double-spiral structure.
Further, the gas inlet of the gas lance is connected with the CO2A pressure reducing valve is arranged between the pressure air supply devices, and an air path circulating one-way valve is arranged between the air inlet of the air injection pipe and the air path circulating outlet.
Further, the inner diameter of the cavity of the lower part of the feed pipe is gradually reduced.
Further, the pipe diameter of the gas-liquid mixing pipe gradually decreases from the position of the gas inlet downwards.
Further, the outlet end of the counter-flow mixer is also connected with a spray pipe, and the position of the free end of the spray pipe is positioned below the middle part of the carbonization reaction tank.
The invention also provides a dolomite calcined dolomite digestion and separation method, which comprises the following steps:
s1, digesting the first calcined dolomite with water to obtain a digestive emulsion;
s2, adding an inhibitor into the digestive emulsion, wherein the inhibitor comprises one or more of ethylenediamine tetraacetic acid, sodium hexametaphosphate, polyacrylic acid, polymaleic acid and nitrilotriacetic acid;
s3, passing the digestive emulsion with the inhibitor added through the feed port, and CO with pressure2Sending the dolomite calcined dolomite into the dolomite digestion and separation device through the air injection pipe to carry out carbonization reaction;
s4, when the pH value of the carbonized slurry in the carbonization reaction tank is 7.0-7.8, taking out the carbonized slurry and carrying out solid-liquid separation to obtain calcium carbonate precipitate and magnesium bicarbonate solution.
Further, the method also comprises the following steps:
s5, circulating the decomposed mother liquor after the magnesium bicarbonate solution is decomposed and mixing the decomposed mother liquor with calcined dolomite of a subsequent batch to be used as new digestive emulsion, and returning to the step S3.
Further, the adding proportion of the calcined dolomite of the first batch to water and the solid-to-liquid ratio of the calcined dolomite of the subsequent batch to the decomposition mother liquor are both 1kg: 10-30L.
Furthermore, the addition amount of the inhibitor is 0.01-0.05% of the mass fraction of the digestive emulsion.
Compared with the prior art, the invention has the following advantages:
the invention provides a dolomite calcined dolomite digestion and separation device, which can separate calcium and magnesium more thoroughly with lower cost.
Specifically, through the setting be located inside the carbonization reaction tank the gas-liquid mixture pipe, be used for liquid circulation the inlet pipe and be used for spouting into gaseous jet-propelled pipe, under the high-speed liquid effect, make mechanical energy transform into the surface energy of gas-liquid, the carbon dioxide is cut into the microbubble.
On the basis, the gas-liquid mixing pipe has higher injection force, so that the gas-liquid mixture is vertically injected into the convection mixing injection pipe under the driving of the injection force, and the contact frequency of carbon dioxide and digestive emulsion in a short time can be remarkably improved by virtue of the high-speed fluidity of the gas-liquid mixture and the reverse convection action in the convection mixing injection pipe; and because the convection mixing injection pipe is positioned in the carbonization reaction tank, the gas-liquid mixture after high-frequency contact can immediately enter the carbonization reaction tank and is injected into the carbonization reaction tank, so that the tightness between gas and liquid is continuously kept.
The more visual description is as follows: the gas-liquid mixing pipe, the feeding pipe and the gas injection pipe enable carbon dioxide to be cut into micro-bubbles, and under the action of vertical jet force and reverse convection, the contact frequency of the micro-bubbles and digestive emulsion can be instantly improved by a plurality of times. The gas-liquid mixing pipe and the convection mixing pipe are arranged up and down, so that the weakening of the injection force can be avoided; in addition, the pipe diameter of the lower part of the gas-liquid mixing pipe is gradually reduced, so that the higher injection speed of the gas-liquid mixture in the process of entering the convection mixing injection pipe can be further ensured, the contact frequency between gas and liquid can be instantly improved, and the efficiency of the carbonization reaction is improved.
The invention also provides a dolomite calcined dolomite digestion and separation method, which improves the specific process on the basis of the dolomite calcined dolomite digestion and separation device, the improved process is simpler in operation, and calcium and magnesium can be efficiently separated; specifically, the inhibitor is added into the digestive emulsion in the carbonization process, and the pH value of the system in the carbonization process is controlled, so that the calcium carbonate can be inhibited from being converted into calcium bicarbonate, and the calcium and the magnesium in the system are thoroughly separated; meanwhile, the digestive emulsion of the subsequent batch is digested by adopting the decomposed mother liquor, most of the inhibitor can be recycled, the production cost is greatly reduced, and green production is realized.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.
FIG. 1 is a schematic structural view of a dolomite calcined dolomite digestion and separation apparatus according to an embodiment of the present invention;
FIG. 2 is a schematic view showing the structure of a gas-liquid mixing reactor according to an embodiment of the present invention;
FIG. 3 is a schematic structural view of a convective mixing jet pipe in one embodiment of the present invention;
FIG. 4 is a schematic flow diagram of a dolomite calcined dolomite digestion separation method according to an embodiment of the present invention.
The reference numbers illustrate: a carbonization reaction tank 1; a feed inlet 2; a gas circuit circulation outlet 3; a waterway circulation outlet 4; a drain valve 5; a temperature display interface 6; a pressure display interface 7; a liquid level display interface 8; an access opening 9; a gas-liquid mixing reactor 10; a feed pipe 11; a gas lance 12; a pressure reducing valve 13; a gas circuit circulation check valve 14; a gas-liquid mixing pipe 15; a convection mixing jet pipe 16; a forward flow mixer 17; a counter-current mixer 18; a circulation pump 19; a circulation pump inlet valve 20; and a recirculating pump outlet valve 21.
The implementation, functional features and advantages of the present invention will be further explained with reference to the accompanying drawings.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.
It should be noted that all the directional indicators (such as the upper and lower … …) in the embodiment of the present invention are only used to explain the relative position relationship, movement, etc. of the components in a specific posture (as shown in the drawings), and if the specific posture is changed, the directional indicator is changed accordingly.
In addition, the descriptions related to "first", "second", etc. in the present invention are only for descriptive purposes and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature.
Moreover, the technical solutions in the embodiments of the present invention may be combined with each other, but it is necessary to be able to be realized by a person skilled in the art, and when the technical solutions are contradictory or cannot be realized, the combination of the technical solutions should be considered to be absent, and is not within the protection scope of the present invention.
As shown in fig. 1-3, the invention provides a dolomite calcined dolomite digestion separation device, which is a carbonization reaction device utilizing digestive emulsion and is used for completing the separation of calcium and magnesium in the dolomite digestive emulsion, and comprises a carbonization reaction tank 1, a gas-liquid mixing reactor 10 and a circulating pump 19; of course, multiple lines for delivering digestive emulsions or carbon dioxide may be included and provided for communication.
In order to facilitate the feeding of digestive emulsion and gas-liquid circulation, the top of the carbonization reaction tank 1 is provided with a feeding port 2 for calcined dolomite digestive juice to enter and an air circuit circulation outlet 3; the bottom of the carbonization reaction tank 1 is provided with a waterway circulation outlet 4 and a drain valve 5, and the drain valve 5 is a drain port provided with a control valve. In addition, a temperature display interface 6, a pressure display interface 7, a liquid level display interface 8 and an access hole 9 can be further formed in the carbonization reaction tank 1, so that a worker can conveniently monitor the carbonization reaction and maintain the carbonization reaction tank 1.
In order to sufficiently react the digestive emulsion with the carbon dioxide gas, the gas-liquid mixing reactor 10 includes a gas-liquid mixing pipe 15, a feed pipe 11, and a gas injection pipe 12; the gas-liquid mixing pipe 15 is installed inside the carbonization reaction tank 1, and may be specifically installed on the upper portion of the carbonization reaction tank 1, so that a sufficient accommodating space is reserved in the carbonization reaction tank 1 to facilitate the carbonization reaction; the feeding hole of the feeding pipe 11 is positioned outside the carbonization reaction tank 1, and the outlet end of the feeding pipe 11 is inserted into the gas-liquid mixing pipe 15 from the top of the gas-liquid mixing pipe 15; the gas and liquidThe interface between the mixing pipe 15 and the feeding pipe 11 is sealed by a sealing member (not numbered in the figure), that is, the top of the gas-liquid mixing pipe 15 is provided with a sealing member to seal the top of the convection mixing injection pipe 16, besides, the lower end of the gas-liquid mixing pipe 15 is communicated with the carbonization reaction tank 1, and the side wall of the gas-liquid mixing pipe 15 is provided with a gas inlet (not numbered in the figure); the gas inlet end of the gas lance 12 is simultaneously connected with the CO2The pressure gas supply device is communicated with the gas circuit circulating outlet 3, and the exhaust end of the gas ejector pipe 12 is fixedly arranged with the gas inlet; and the vertical position of the discharge hole of the feeding pipe 11 is lower than the gas inlet, so that the carbon dioxide enters the gas-liquid mixing pipe 15 under the driving of the digestive emulsion flowing at a high speed and is cut into micro bubbles by the digestive emulsion.
In order to facilitate the supply of gas to the gas-liquid mixing pipe 15 and the recycling of unreacted carbon dioxide, the gas inlet of the gas injection pipe 12 and the CO are connected2A pressure reducing valve 13 is arranged between the pressure gas supply devices to reduce the CO2The carbon dioxide provided by the pressure gas supply device is used for regulating the gas pressure, and a gas circuit circulating one-way valve 14 is arranged between the gas inlet of the gas spraying pipe 12 and the gas circuit circulating outlet 3 to prevent the CO from being generated2The carbon dioxide provided by the pressure gas supply device generates a shunt flow in the gas inlet process. Furthermore, in order to enable the gas lance 12 to receive the CO simultaneously2The pressure reducing valve 13 and the corresponding pipeline thereof can be connected in parallel with the gas circuit circulation one-way valve 14 and the corresponding pipeline thereof.
It should be understood that the normal working air pressure of the carbonization reaction tank 1 is micro-positive pressure, about 20 to 40KPa, when the carbonization reaction tank 1 is continuously operated in combination with the circulating pump 19, the digestive emulsion in the carbonization reaction tank 1 can continuously absorb CO2The pressure in the reactor is reduced, so that the constant pressure valve is equipped to keep CO at all times during continuous operation2Supply and required pressure. On this basis, relief pressure valve 13 can use with the constant pressure valve collocation, the constant pressure valve can set up in on jet-propelled pipe 12, also can set up in jet-propelled pipe 12 and the pressure reducing valve 13.
As a structural design of the gas-liquid mixing reactor 10, in order to make the digestive emulsion and the gas-liquid mixture obtained by mixing the digestive emulsion with carbon dioxide have higher injection speed, the inner diameter of the tube cavity at the lower part of the feeding tube 11 is gradually reduced; further, the inner diameter of the lower lumen of the gas-liquid mixing pipe 15 can be gradually reduced, that is, the diameter of the gas-liquid mixing pipe 15 can be gradually reduced from the position of the gas inlet, on this basis, the discharge end of the feed pipe 11 can be extended to the lower portion of the gas-liquid mixing pipe 15, and a gap is required to be maintained between the feed pipe 11 and the inner wall of the gas-liquid mixing pipe 15, so as to allow the carbon dioxide gas to flow.
In order to ensure the high-speed flow of the digestive emulsion, the liquid inlet of the circulating pump 19 is communicated with the waterway circulation outlet 4, and the liquid outlet of the circulating pump 19 is communicated with the material inlet of the feeding pipe 11, so as to pump the digestive emulsion in the carbonization reaction tank 1 into the feeding pipe 11 at a high speed, so that the digestive emulsion entering the feeding pipe 11 enters the gas-liquid mixing pipe 15 from top to bottom at a high flow rate, and drives the carbon dioxide gas to flow, and then the carbon dioxide gas is cut. Wherein, be equipped with circulating pump inlet valve 20 between circulating pump 19 with waterway circulation export 4, circulating pump 19 with be equipped with circulating pump outlet valve 21 between the feed inlet of inlet pipe 11 to control the liquid in the circulation.
It should be noted that the gas-liquid mixing reactor 10 further includes a convection mixing injection pipe 16 vertically connecting the outlet of the gas-liquid mixing pipe 15 and the carbonization reaction tank 1, the convection mixing injection pipe 16 is disposed below the gas-liquid mixing pipe 15, and the convection mixing injection pipe 16 is sequentially provided with a forward flow mixer 17 and a reverse flow mixer 18 from top to bottom; the convection mixing and injecting pipe 16 and the gas-liquid mixing pipe 15 may be integrally provided or may be fixedly connected, both of which are vertically arranged, and the gas-liquid mixture obtained in the gas-liquid mixing pipe 15 enters the convection mixing pipe from the lower end opening of the gas-liquid mixing pipe 15, is mixed by convection of the forward flow mixer 17 and the backward flow mixer 18, and then is injected into the carbonization reaction tank 1. Furthermore, a lance can also be connected to the outlet end of the counter-flow mixer 18, and the position of the free end of the lance can be below the middle of the carbonation reaction tank 1.
As an explanation of the forward flow mixer 17 and the backward flow mixer 18: the forward flow mixer 17 is mainly used for generating forward rotation to the gas-liquid mixture flowing downward, and the backward flow mixer 18 is mainly used for generating backward rotation to the gas-liquid mixture flowing downward, the forward rotation and the backward rotation are opposite concepts, and only the rotation directions of the forward rotation and the backward rotation are opposite, in general, the forward rotation can be understood as clockwise rotation, and the backward rotation can be understood as counterclockwise rotation.
Specifically, the forward flow mixer 17 includes a first pipe and a first spiral protrusion protruding from the inner wall of the first pipe, and the backward flow mixer 18 includes a second pipe and a second spiral protrusion protruding from the inner wall of the second pipe, and the spiral directions of the first spiral protrusion and the second spiral protrusion are opposite. The first pipe body and the second pipe body can be integrally arranged and can also be fixedly connected through a fixing piece. Alternatively, the spiral direction of the first spiral protrusion may be a clockwise direction, the spiral direction of the second spiral protrusion may be a counterclockwise direction, and both the first spiral protrusion and the second spiral protrusion may have a double-spiral structure, or of course, may have a single-spiral structure. In addition, it should be understood that the forward flow mixer 17 and the backward flow mixer 18 can form high-speed convection of gas and liquid, so that the mixing reaction is more sufficient and the reaction is more efficient. Specifically, under the action of vertical jet force and reverse convection, the contact frequency of the micro-bubbles and the digestive emulsion can be instantly increased by an infinite number of times.
The operation mode of the above embodiment may be: the digestive emulsion placed in the carbonation reaction tank 1 is conveyed into the feeding pipe 11 by the circulating pump 19 and flows into the gas-liquid mixing pipe 15 along the discharge port of the feeding pipe 11, the digestive emulsion has a high flow rate when passing through the feeding pipe 11 due to the pumping action of the circulating pump 19 and the structural design of the feeding pipe 11, and the negative pressure generated by the digestive emulsion flowing at a high speed can make carbon dioxide gas enter the gas-liquid mixing pipe 15 from the gas injection pipe 12. Under the action of the high-speed liquid, the mechanical energy is converted into the surface energy of gas and liquid, the carbon dioxide is cut into micro bubbles, and under the further action of the forward flow mixer 17 and the reverse flow mixer 18, the carbon dioxide and the digestive milk are further mixed, so that the carbon dioxide and the digestive milk are mixed at high frequency. The micro carbon dioxide bubbles and calcium and magnesium ions in the digestive emulsion are quickly mixed and react to generate carbonate precipitates (magnesium carbonate and calcium carbonate), small carbonate particles continue to react with the carbon dioxide bubbles in a high-speed liquid flow, the magnesium carbonate particles can generate magnesium bicarbonate to be dissolved in the solution, and finally the deep separation of the calcium and the magnesium can be realized by controlling the pH value at the end point of the reaction to be 7.5-8.0. In addition, the unreacted carbon dioxide gas rises and returns to the gas lance 12 through the gas circuit recycle outlet 3 for recycling.
In the above embodiment, the solid-liquid separation of the carbonized slurry obtained in the dolomite calcined dolomite digestion separation apparatus may be performed by a known conventional treatment method, for example: plate-frame filter pressing, centrifugal separation and the like. The subsequent processing mode of the heavy magnesium water (magnesium bicarbonate solution) obtained after the solid-liquid separation of the carbonized slurry can also be carried out by adopting a known conventional treatment method, including pyrolysis, vacuum decomposition or special equipment decomposition and the like. The decomposed mother liquor is returned to the digestion process to be used for digesting calcined dolomite so as to obtain the digestion emulsion for carrying out carbonization reaction.
In order to realize the complete separation of calcium and magnesium, the invention also provides a dolomite calcined dolomite digestion separation method, wherein a dolomite digestion emulsion is sent to the dolomite calcined dolomite digestion separation device through the feed opening 2 and carbon dioxide is sent to the dolomite calcined dolomite digestion separation device through the gas injection pipe 12 to be carbonized and reacted with the carbon dioxide, so as to obtain calcium carbonate precipitation and magnesium bicarbonate solution.
Specifically, as will be appreciated with reference to fig. 4, the dolomite burnt lime digestion separation method may include the steps of:
and S1, digesting the first calcined dolomite with water to obtain the digestive emulsion. The adding proportion of the calcined dolomite and water in the first batch can be 1kg: 10-30L, the digestion temperature of the calcined dolomite is generally 30-80 ℃, the digestion time is generally 1-3 h, stirring and other operations are required in the digestion process, and the digestion emulsion obtained by digestion is generally filtered to remove residues which cannot be sufficiently digested.
S2, adding an inhibitor into the digestive emulsion, wherein the inhibitor comprises one or more of ethylenediamine tetraacetic acid, sodium hexametaphosphate, polyacrylic acid, polymaleic acid and nitrilotriacetic acid; the inhibitor mainly acts to inhibit the generated calcium carbonate precipitate from reacting with carbon dioxide to generate calcium bicarbonate in the calcium and magnesium ion carbonization process. Alternatively, the addition amount of the inhibitor may be 0.01 to 0.05% by mass, preferably 0.01 to 0.02% by mass of the digestive emulsion.
S3, passing the digestive emulsion added with the inhibitor through the feed opening 2, and sending carbon dioxide with pressure into the dolomite calcined dolomite digestion separation device for carbonization reaction through the air injection pipe 12; wherein the reaction pressure of the carbonization reaction can be 20-40 kPa.
S4, when the pH value of the carbonized slurry in the carbonization reaction tank is 7.0-7.8, taking out the carbonized slurry and carrying out solid-liquid separation to obtain calcium carbonate precipitate and magnesium bicarbonate solution. It is to be noted that, in the case where the inhibitor is added, since the dissolution of calcium can be suppressed by the presence of the inhibitor, the reaction end point pH can also be controlled to 7.0 to 7.8 in order to improve the dissolution efficiency of magnesium in the case where the dissolution of calcium is suppressed.
S5, circulating the decomposed mother liquor after the magnesium bicarbonate solution is decomposed and mixing the decomposed mother liquor with calcined dolomite of a subsequent batch to be used as new digestive emulsion, and returning to the step S3.
The solid-to-liquid ratio of the calcined dolomite of the subsequent batch to the decomposition mother liquor can also be 1kg: 10-30L; the calcined dolomite is digested by the decomposition mother liquor, the aim is mainly to recover the inhibitor in the decomposition mother liquor and utilize the heat in the decomposition mother liquor, and the inhibitor can be supplemented properly in the process.
In the above embodiment, the carbonized slurry after carbonization is subjected to solid-liquid separation, so as to obtain a calcium carbonate solution and a magnesium bicarbonate solution through separation, the magnesium bicarbonate solution is subjected to a subsequent decomposition process (such as pyrolysis) to obtain a filtrate and basic magnesium carbonate, the filtrate is returned to a digestion system as a digestion solution, so as to realize recycling of the inhibitor, and it is clear that the decomposition mother solution is a clear solution obtained by performing pyrolysis on heavy magnesium water after carbonization reaction to separate basic magnesium carbonate.
As a specific description of the above embodiment, the present invention is mainly directed to digestion and carbonization separation in the dolomite processing process, and the dolomite processing process generally includes crushing dolomite, calcining at high temperature to obtain calcined dolomite, digesting the calcined dolomite to obtain a digestion emulsion, carbonizing the digestion emulsion to separate calcium and magnesium, obtaining a carbonized slurry with a lower calcium ion concentration, filtering to separate solid and liquid, obtaining calcium carbonate and heavy magnesium water, and pyrolyzing the obtained heavy magnesium water to obtain basic magnesium carbonate and a recycled decomposition mother liquor.
The principle of calcium and magnesium separation in the above embodiment is as follows: in the above embodiment, the gas-liquid mixing reactor 10 is used to replace the stirring gas-liquid mixing and contact tower mixing in the prior art, and the digestive emulsion can be brought into close contact with carbon dioxide by matching the gas-liquid mixing reactor 10 with the circulating pump 19 and circulating, draining and carbonizing under the condition of closed pressurization; in addition, by controlling the pH value of the system in the carbonization process, the carbonization and separation efficiency of magnesium hydroxide and calcium hydroxide in the dolomite digestion slurry is higher, the purity of the obtained calcium carbonate product is better, and the overall production yield is further improved. The high-efficiency calcium and magnesium separation is conveniently realized, and the added inhibitor can be easily separated and recovered, so that the production cost is greatly reduced.
In the carbonization process of the digestive emulsion, the system is gradually acidified and the pH value of the system is gradually reduced along with the introduction of carbon dioxide. And as the pH value of the system is reduced, the water is eliminatedThe emulsion is dissolved to generate calcium carbonate and magnesium carbonate precipitates in the first stage, and the magnesium carbonate and the calcium carbonate react with excessive carbon dioxide to generate magnesium bicarbonate and calcium bicarbonate in the second stage. Inhibitor is mixed with free Ca in the second stage of carbonization2+Performing coordination reaction to free Ca2+Not in the form of calcium bicarbonate in the solution. By controlling the pH value (7.0-7.8) of the reaction end point and the double action of the inhibitor, the calcium ions are prevented from forming precipitates and entering the product of basic magnesium carbonate in the subsequent decomposition stage, and the deep separation of the calcium and magnesium ions is realized.
One specific embodiment of the calcium and magnesium separation treatment method is as follows: adding an inhibitor into the digestive emulsion at the temperature of 20-40 ℃, wherein the total adding amount of the inhibitor is 0.01-0.02% of the mass fraction of the digestive emulsion, pumping the digestive emulsion added with the inhibitor into the carbonization reaction tank 1, the pH value of the digestive emulsion is 13.1, then introducing carbon dioxide, and controlling the pressure in the carbonization reaction tank 1 to be 20-40 kPa; when the carbon dioxide and the digestive emulsion are fully carbonized to the pH value of 7.5, the carbonized slurry is pumped into a plate-and-frame filter press for separation, filter residue is light calcium carbonate, the effective content of the calcium carbonate is more than 97 percent, and filtrate is heavy magnesium water, namely magnesium bicarbonate solution. Pyrolyzing the magnesium bicarbonate solution at 30-70 ℃ for 45min, feeding the magnesium bicarbonate solution into a plate-and-frame filter press for separation, wherein the filter residue is basic magnesium carbonate, the content of magnesium oxide is 41.52%, the content of calcium oxide is 0.15%, the requirements of high-class products in standard HG/T2959-2010 industrial hydrated basic magnesium carbonate are met, and the deep separation of calcium and magnesium in the emulsion is realized.
In the above technical solutions, the above are only preferred embodiments of the present invention, and the technical scope of the present invention is not limited thereby, and all the technical concepts of the present invention include the claims of the present invention, which are directly or indirectly applied to other related technical fields by using the equivalent structural changes made in the content of the description and the drawings of the present invention.

Claims (10)

1. A dolomite calcined dolomite digestion separation device is characterized by comprising a carbonization reaction tank, a gas-liquid mixing reactor and a circulating pump; wherein the content of the first and second substances,
the top of the carbonization reaction tank is provided with a feed inlet and an air path circulating outlet for calcined dolomite digestion liquid to enter, and the bottom of the carbonization reaction tank is provided with an air path circulating outlet and a drainage valve;
the gas-liquid mixing reactor comprises a gas-liquid mixing pipe, a feeding pipe, a gas spraying pipe and a convection mixing injection pipe; the feed inlet of the feed pipe is positioned outside the carbonization reaction tank, and the outlet end of the feed pipe is inserted into the gas-liquid mixing pipe from the top of the gas-liquid mixing pipe; the gas-liquid mixing pipe is arranged inside the carbonization reaction tank, the interface of the gas-liquid mixing pipe and the feeding pipe is sealed by a sealing element, and the side wall of the gas-liquid mixing pipe is also provided with a gas inlet; the gas inlet end of the gas injection pipe is simultaneously connected with CO2The pressure gas supply device is communicated with the gas circuit circulating outlet, and the exhaust end of the gas ejector pipe is fixedly installed with the gas inlet; the vertical position of the discharge hole of the feeding pipe is lower than that of the air inlet;
the convection mixing and spraying pipe is arranged below the gas-liquid mixing pipe, the outlet of the gas-liquid mixing pipe is vertically communicated with the carbonization reaction tank, and the convection mixing and spraying pipe is sequentially provided with a forward flow mixer and a reverse flow mixer from top to bottom;
the forward flow mixer comprises a first pipe body and a first spiral bulge convexly arranged on the inner wall of a pipe cavity of the first pipe body, the backward flow mixer comprises a second pipe body and a second spiral bulge convexly arranged on the inner wall of a pipe cavity of the second pipe body, and the spiral directions of the first spiral bulge and the second spiral bulge are opposite;
the inlet of circulating pump with water route circulation export intercommunication, the liquid outlet of circulating pump with the feed inlet intercommunication of inlet pipe.
2. A dolomite calcined dolomite digestion separating apparatus according to claim 1, wherein the first and second spiral lobes are both of double helix configuration.
3. The white cloud of claim 1The lime calcining digestion separation device is characterized in that the air inlet of the air injection pipe is connected with the CO2A pressure reducing valve is arranged between the pressure air supply devices, and an air path circulating one-way valve is arranged between the air inlet of the air injection pipe and the air path circulating outlet.
4. A dolomite calcined dolomite digestion separation apparatus according to claim 1, wherein the internal diameter of the lumen of the lower part of the feed pipe is gradually reduced.
5. A dolomite calcined dolomite digestion separation apparatus according to claim 4, wherein the pipe diameter of the gas-liquid mixing pipe decreases gradually from the position of the gas inlet downwards.
6. A dolomite calcined dolomite digestion separation apparatus according to claim 2, wherein the outlet end of the reverse flow mixer is further connected with a spray pipe, the position of the free end of the spray pipe is below the middle of the carbonization reaction tank.
7. A dolomite calcined dolomite digestion separation method is characterized by comprising the following steps:
s1, digesting the first calcined dolomite with water to obtain a digestive emulsion;
s2, adding an inhibitor into the digestive emulsion, wherein the inhibitor comprises one or more of ethylenediamine tetraacetic acid, sodium hexametaphosphate, polyacrylic acid, polymaleic acid and nitrilotriacetic acid;
s3, passing the digestive emulsion with the inhibitor added through the feed port, and CO with pressure2Sending the dolomite calcined dolomite into a digestion and separation device according to any one of claims 1 to 6 through the gas injection pipe for carbonization reaction;
s4, when the pH value of the carbonized slurry in the carbonization reaction tank is 7.0-7.8, taking out the carbonized slurry and carrying out solid-liquid separation to obtain calcium carbonate precipitate and magnesium bicarbonate solution.
8. A dolomite calcined dolomite digestion separation method according to claim 7, further comprising the steps of:
s5, circulating the decomposed mother liquor after the magnesium bicarbonate solution is decomposed and mixing the decomposed mother liquor with calcined dolomite of a subsequent batch to be used as new digestive emulsion, and returning to the step S3.
9. The dolomite calcined dolomite digestion and separation method according to claim 8, wherein the adding proportion of the calcined dolomite of the first batch to water and the solid-to-liquid ratio of the calcined dolomite of the subsequent batch to the decomposition mother liquor are 1kg: 10-30L.
10. A dolomite calcined dolomite digestion separation method according to claim 7, wherein the addition amount of the inhibitor is 0.01-0.05% of the mass fraction of the digestion emulsion.
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