CN111321310A - Method and system for preparing magnesium metal - Google Patents

Method and system for preparing magnesium metal Download PDF

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Publication number
CN111321310A
CN111321310A CN202010084598.2A CN202010084598A CN111321310A CN 111321310 A CN111321310 A CN 111321310A CN 202010084598 A CN202010084598 A CN 202010084598A CN 111321310 A CN111321310 A CN 111321310A
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CN
China
Prior art keywords
magnesium
induction furnace
optionally
furnace
reducing
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Pending
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CN202010084598.2A
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Chinese (zh)
Inventor
李东波
梁文玉
黎敏
朱立江
姚心
张富信
代文彬
黄超
吕东
刘诚
郭天宇
曹珂菲
辛鹏飞
徐小锋
吴卫国
王书晓
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China ENFI Engineering Corp
Beijing Metallurgical Equipment Research Design Institute Co Ltd
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China ENFI Engineering Corp
Beijing Metallurgical Equipment Research Design Institute Co Ltd
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Priority to CN202010084598.2A priority Critical patent/CN111321310A/en
Publication of CN111321310A publication Critical patent/CN111321310A/en
Pending legal-status Critical Current

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    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22BPRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B26/00Obtaining alkali, alkaline earth metals or magnesium
    • C22B26/20Obtaining alkaline earth metals or magnesium
    • C22B26/22Obtaining magnesium
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22BPRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B5/00General methods of reducing to metals
    • C22B5/02Dry methods smelting of sulfides or formation of mattes
    • C22B5/04Dry methods smelting of sulfides or formation of mattes by aluminium, other metals or silicon

Abstract

The invention discloses a method and a system for preparing magnesium metal. The preparation method comprises the following steps: (1) carrying out melting treatment on a reducing agent or a mixture of the reducing agent and a fluxing agent so as to obtain a reducing liquid; (2) blowing forging white or a mixture of the forging white and a fluxing agent into the reducing liquid for reduction treatment so as to obtain magnesium-containing flue gas, metal melt and smelting slag; (3) and (3) condensing the magnesium-containing flue gas to obtain a magnesium metal liquid and magnesium-removed flue gas, wherein the steps (1) to (2) are carried out in a closed environment under normal pressure or positive pressure. The method can realize continuous reduction smelting of the magnesium metal under normal pressure or positive pressure, improve the heat utilization rate, the production efficiency, the raw material utilization rate and the metal recovery rate, and improve the field operation environment.

Description

Method and system for preparing magnesium metal
Technical Field
The invention belongs to the field of metallurgy, and particularly relates to a method and a system for preparing magnesium metal.
Background
At present, the preparation of over 95 percent of metal magnesium at home adopts a vacuum silicothermic reduction process, namely a Pidgeon process, which is mainly characterized in that dolomite is calcined into calcined dolomite, then the calcined dolomite is mixed with fluorite and 75 ferrosilicon (with the Si content of over 75 percent) and ground into powder, the powder is pressed into a ball shape, and then the ball shape is filled into a high-temperature resistant steel tank with one sealed end; heating the steel tank by burning natural gas or coal gas, vacuumizing the tank to reduce MgO in calcined dolomite by Si in ferrosilicon to obtain magnesium vapor, and condensing the magnesium vapor into solid crude magnesium at the opening end of the reduction tank, wherein the crude magnesium is refined and purified. Wherein, if the magnesium metal reduction is carried out under normal pressure (101.325KPa), the required reaction temperature is above 1550 deg.C, and when the pressure is 13.3Pa, the required reaction temperature can be reduced to 1100 deg.C. Therefore, the vacuum system can reduce the magnesium reduction temperature, but the power consumption of the system is large under the vacuum low pressure. In addition, because the Pidgeon production adopts a closed tank type reduction process, the technical automation level is low, the whole production process needs manual operation and comprises the procedures of filling raw materials, opening a tank to take ingots, removing slag and cleaning the tank and the like, and pollutants such as on-site smoke dust, high temperature, noise, smoke and the like are numerous, thereby seriously influencing the on-site personal health and safety, and having the defects of discontinuous smelting, long production period, low heat utilization efficiency, heavy on-site environmental pollution, low automation degree, high consumption of heat-resistant steel tanks, high cost, low reaction speed and the like.
In order to improve the intermittent production process of Pidgeon process, France provides a semi-continuous process Marangoni process (Magnetherm), the method uses bauxite and dolomite as raw materials, adopts a central electrode heating mode, the reaction temperature is 1300-1700 ℃, the vacuum degree is 0.266-13.332 kPa, after the raw materials are added into a furnace for melting, the raw materials are vacuumized to reduce metal magnesium vapor, the condensed liquid is converted into liquid magnesium, and after 10 hours of continuous feeding, the depth of slag in the electric furnace can reach 2.4 m; at the moment, cutting off the vacuum, injecting inert gas, reducing the input power of the transformer and maintaining the necessary furnace temperature; then discharging residual lean iron (the mass fraction of Si is 18%) and lean magnesium slag (the mass fraction of MgO is 6%); subsequently, a second production cycle is started; when the second production cycle is complete, the magnesium condenser tube is removed and replaced with an empty canister. The method adopts the alternating current electrode for heating, and because the electric furnace system is large in volume and insufficient in vacuum degree, the dolomite raw material is directly filled into the furnace, and carbonate in the dolomite can generate high-temperature endothermic decomposition reaction, the temperature is very high when the electric furnace smelts magnesium, the whole production period of magnesium smelting is 16-24h, 3-8t of metal magnesium can be produced in one day, 7t of magnesium raw material is consumed per ton, and the production efficiency is relatively low. In addition, there is a method of reducing magnesium oxide by carbothermic reduction under vacuum, but this method involves carbon reductionUnstable reaction, easy CO generation of magnesium vapor2Oxidation, difficult separation of gas and other technical defects; or a double-vacuum tank type smelting method is adopted, one set of vacuum tank is used for smelting ferrosilicon under the vacuum degree of 8-5000 Pa, the other set of vacuum tank is used for smelting magnesium, and the two sets of vacuum tanks are sequentially carried out in turn, so that the continuous production of the magnesium metal is realized.
Thus, the smelting process of magnesium still needs to be further improved.
Disclosure of Invention
The invention is mainly proposed based on the following technical defects in the existing magnesium smelting process:
1. most procedures in a production field depend on manual operation, so that the labor intensity is high, and the potential safety hazard is high; 2. the magnesium smelting is intermittent production, the reduction period is long, and the production efficiency is low; 3. the production process is fully open, more dust and waste gas are generated on site, the noise is high, and the environmental pollution is serious; 4. the vacuum reduction tank has high price, short service period and large use amount; 5. the reduction smelting adopts an external heating mode, so that the heat utilization efficiency is low; 6. the magnesium reduction reaction is a solid-solid reaction, the reaction rate is slow, and the utilization rate of raw materials is low; 7. reduction smelting needs to be carried out under a vacuum condition, a vacuum system is complex, and the operation energy consumption is high; 8. the reduced magnesium vapor is condensed into solid state at the opening of the tank, has more impurities, needs to be melted and purified again, and has high energy consumption.
The present invention is directed to solving, at least to some extent, one of the technical problems in the related art.
To this end, it is an object of the present invention to propose a method and a system for producing magnesium metal. The method can realize continuous reduction smelting of the magnesium metal under normal pressure or positive pressure, improve the heat utilization rate, the production efficiency, the raw material utilization rate and the metal recovery rate, and improve the field operation environment.
According to a first aspect of the present invention, a method of producing magnesium metal is presented. According to an embodiment of the invention, the method comprises:
(1) carrying out melting treatment on a reducing agent or a mixture of the reducing agent and a fluxing agent so as to obtain a reducing liquid;
(2) blowing forging white or a mixture of the forging white and a fluxing agent into the reducing liquid for reduction treatment so as to obtain magnesium-containing flue gas, metal melt and smelting slag;
(3) condensing the magnesium-containing flue gas to obtain magnesium metal liquid and magnesium-removed flue gas,
wherein the steps (1) to (2) are carried out in a closed environment under normal pressure or positive pressure.
The method for preparing the magnesium metal of the embodiment of the invention at least has the following advantages: 1. compared with the existing vacuum reduction magnesium preparation process, the method is carried out under normal pressure or positive pressure, vacuum operation is not needed, the burden of a vacuum system is small, and energy and power consumption is low; 2. the smelting process is carried out in a closed environment, so that the environmental pollution is low, the noise is low, and the field operation environment is obviously improved; 3. the melting treatment and the reduction treatment can be carried out in one reaction furnace without melt transfer, thereby not only shortening the process flow, but also greatly reducing the heat loss and obviously improving the heat utilization efficiency; 4. continuous feeding and discharging can be realized, the continuous production of the metal magnesium is realized, and the utilization rate of raw materials, the production efficiency and the metal recovery rate are high; 5. the production system can be simplified and the production cost can be significantly reduced.
In addition, the method for preparing metallic magnesium according to the above embodiment of the present invention may further have the following additional technical features:
in some embodiments of the present invention, the method of preparing magnesium metal further comprises: (4) and (3) performing dust removal and drying treatment on the magnesium-removed flue gas, and then recycling the magnesium-removed flue gas as a blowing carrier in the step (2).
In some embodiments of the present invention, the steps (1) to (2) are performed under an inert atmosphere of 0.1 to 0.3 MPa.
In some embodiments of the invention, in the step (1), the temperature of the melting treatment is 1300-1500 ℃,
in some embodiments of the present invention, the reducing agent is at least one selected from the group consisting of a silicon-iron alloy, a silicon-calcium alloy, a silicon-manganese alloy, metallic aluminum, and metallic calcium, and the flux is at least one selected from the group consisting of fluorite, potassium fluoride, and sodium fluoride.
In some embodiments of the invention, the particle size of the reducing agent is 5-50 mm, and the particle size of the fluxing agent is 0.1-30 mm.
In some embodiments of the invention, in the step (2), the temperature of the reduction treatment is 1300-1500 ℃,
in some embodiments of the invention, step (2) further comprises: and (3) replenishing a reducing agent and/or a fluxing agent into the reducing solution.
In some embodiments of the invention, in the step (2), the blowing manner includes at least one of bottom blowing, side blowing and top blowing.
In some embodiments of the invention, in the step (2), the forged blank or the mixture of the forged blank and the fluxing agent is blown into the reducing liquid by taking inert gas as a blowing carrier, and the blown gas-solid mass ratio is 1: (10-100).
In some embodiments of the invention, in the step (2), the dolomites are obtained by calcining dolomite at 800-850 ℃ for 1.5-3 h.
In some embodiments of the present invention, in step (2), the forged steel sheet has a grain size of not more than 1mm, preferably a fraction having a grain size of not more than 75 μm of not less than 90 wt%; the flux has a particle size of not more than 1mm, and preferably a portion having a particle size of not more than 75 μm is not less than 90 wt%.
In some embodiments of the present invention, steps (1) - (2) are performed in an induction furnace disposed in a sealed chamber, the pressure within the sealed chamber being greater than the pressure within the induction furnace.
In some embodiments of the invention, the pressure in the induction furnace is 0.1-0.2 MPa, the pressure in the closed chamber is 0.15-0.3 MPa,
in some embodiments of the invention, the inner lining of the induction furnace is made of graphite refractory material, the secondary outer layer is made of magnesium refractory material, the outermost layer is made of metal shell,
in some embodiments of the invention, the content of the reducing liquid and/or the metal melt is not less than 10-20% of the volume of the hearth of the induction furnace,
in some embodiments of the invention, in the step (1), the initial content of the reducing liquid is 20-35% of the furnace chamber volume of the induction furnace,
in some embodiments of the invention, in the step (2), the content of the metal melt is not higher than 50% of the depth of the hearth of the induction furnace,
in some embodiments of the present invention, the induction furnace and the closed chamber are subjected to a vacuum-pumping process and an inert gas-filling process in advance before the step (1) is performed.
According to a second aspect of the invention, the invention proposes a system for implementing the above method for producing magnesium metal. According to an embodiment of the invention, the system comprises:
the closed chamber is provided with a first inert gas inlet;
the induction furnace is arranged in the closed chamber and comprises a furnace shell, a heating device, a furnace shell lining and a spray gun, the induction furnace is provided with a particle material inlet, a powder material inlet, a second inert gas inlet, a smoke outlet, a smelting slag outlet and a melt outlet, the particle material inlet, the powder material inlet, the second inert gas inlet, the smoke outlet, the smelting slag outlet and the melt outlet penetrate through the closed chamber, the spray gun penetrates through the closed chamber and is inserted into the powder material inlet, a smoke exhaust area and a smelting area which are distributed up and down are defined in a hearth of the induction furnace, and a slag layer area and a melt area which are distributed up and down are defined in the smelting area;
the condensing equipment, condensing equipment includes condenser and the magnesium liquid storage tank that upper and lower intercommunication was arranged, the condenser has the flue gas entry and removes the magnesium exhanst gas outlet, the magnesium liquid storage tank has magnesium liquid export and impurity export, the flue gas entry with the flue gas outlet links to each other.
The system for preparing the magnesium metal of the embodiment of the invention at least has the following advantages: 1. the system has simple structure and low cost, does not need to be provided with a vacuum tank and only has one smelting furnace, has low energy and power consumption in the reaction process, does not need melt transfer, and obviously reduces the heat loss; 2. the system has high automation degree and good tightness, and the induction furnace is arranged in the closed chamber, so that the environmental pollution and noise in the smelting process can be obviously reduced, the production environment is improved, and the heat loss can be further reduced; 3. continuous feeding and discharging can be realized, continuous production of metal magnesium is realized under normal pressure or positive pressure, and the production efficiency, the raw material utilization rate and the metal recovery rate are improved; 4. the smelting process can be carried out in an inert atmosphere, and magnesium steam can be effectively prevented from burning, so that the recovery rate of magnesium is further improved.
In some embodiments of the present invention, the system for producing magnesium metal further comprises: and the first vacuumizing device is connected with the closed chamber and/or the electric induction furnace.
In some embodiments of the present invention, the system for producing magnesium metal further comprises: the dust removal device is connected with the magnesium removal flue gas outlet; and the air inlet of the drying device is connected with the dust removal device, and the air outlet of the drying device is connected with the air emptying device and/or the spray gun.
In some embodiments of the invention, a heat exchange device is arranged between the dust removal device and the magnesium removal flue gas outlet.
In some embodiments of the invention, a supercharger and an inert gas storage tank which are connected in sequence are arranged between the gas outlet of the drying device and the spray gun, and a second vacuum extractor is arranged between the gas outlet of the drying device and the gas emptying device.
In some embodiments of the present invention, the particulate material inlet is connected to a reducing agent bin, the spray gun is connected to a forge material bin, the particulate material inlet and/or the spray gun is connected to a flux bin, and the reducing agent bin, the flux bin and the forge material bin are respectively and independently of each other in an upper-lower double-bin structure.
In some embodiments of the present invention, the reducing agent bin, the flux bin, and the forge white bin are independently connected to the first vacuum apparatus and the inert gas storage tank, respectively.
In some embodiments of the invention, the furnace shell further comprises a metal shell and a secondary outer layer, the secondary outer layer being a layer of magnesium refractory material and the furnace shell lining being a layer of graphite refractory material.
In some embodiments of the invention, the powder inlet is arranged at the bottom and/or the side and/or the top of the induction furnace, and the spray gun is inserted into the powder inlet from the bottom and/or the top of the induction furnace in a direction perpendicular to the horizontal direction and/or from the side of the induction furnace in a direction with an angle of not more than 10 degrees with the horizontal direction.
In some embodiments of the invention, the melt zone is no more than 50% of the depth of the hearth of the induction furnace.
In some embodiments of the invention, the wall of the closed chamber is provided with an insulating layer.
In some embodiments of the invention, the side and/or the bottom of the magnesium liquid storage tank is provided with an insulating layer.
Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
Drawings
The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
fig. 1 is a flow chart of a method of preparing magnesium metal according to one embodiment of the present invention.
Fig. 2 is a schematic structural view of a system for preparing magnesium metal according to an embodiment of the present invention.
Fig. 3 is a schematic structural view of a system for manufacturing magnesium metal according to still another embodiment of the present invention.
Fig. 4 is a schematic structural view of a system for manufacturing magnesium metal according to still another embodiment of the present invention.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.
According to a first aspect of the present invention, a method of producing magnesium metal is presented. According to an embodiment of the invention, with reference to fig. 1, the method comprises: (1) carrying out melting treatment on a reducing agent or a mixture of the reducing agent and a fluxing agent so as to obtain a reducing liquid; (2) blowing forging white or a mixture of the forging white and a fluxing agent into the reducing liquid for reduction treatment so as to obtain magnesium-containing flue gas, metal melt and smelting slag; (3) and (3) carrying out condensation treatment on the magnesium-containing flue gas so as to obtain a magnesium metal liquid and magnesium-removed flue gas, wherein the steps (1) to (2) are carried out in a closed environment under normal pressure or positive pressure. The method can realize continuous reduction smelting of metal magnesium under normal pressure or positive pressure, obviously improve the production efficiency of magnesium smelting, improve the field operation environment, and improve the heat utilization rate, the raw material utilization rate, the magnesium vapor yield and the purity of crude magnesium.
The method for preparing metallic magnesium according to the above embodiment of the present invention will be described in detail with reference to fig. 1.
S100: melting the reducing agent or the mixture of the reducing agent and the fluxing agent in a closed environment under normal pressure or positive pressure to obtain a reducing solution
According to the embodiment of the invention, the reducing agent or the mixture of the reducing agent and the fluxing agent is subjected to melting treatment in the closed environment under normal pressure or positive pressure, so that the vacuum operation is not needed, the load of a vacuum system is small, the energy and power consumption is low, the environmental pollution is low, the noise is low, and the field operation environment is obviously improved.
According to an embodiment of the present invention, the types of the reducing agent and the fluxing agent in the present invention are not particularly limited, and can be selected by those skilled in the art according to actual needs. For example, the reducing agent may be at least one selected from the group consisting of a silicon-iron alloy, a silicon-calcium alloy, a silicon-manganese alloy, metallic aluminum, and metallic calcium, and the flux may be at least one selected from the group consisting of fluorite, potassium fluoride, and sodium fluoride, wherein the silicon-iron alloy has an Si content of not less than 75%. Furthermore, the reducing agent and the fluxing agent may be crushed and sieved in advance before the step (1), wherein the particle size of the reducing agent may be 20 to 50mm, and the particle size of the fluxing agent may be 0.1 to 30mm, for example, 5 to 30mm, so that the melting efficiency and the raw material utilization rate may be further improved.
According to another embodiment of the present invention, the melting process can be performed under an inert atmosphere of 0.1 to 0.3MPa, for example, 0.1 to 0.12MPa, and the inventors found that, if the reaction pressure is too high, not only energy power consumption is large, but also the requirement for the tightness of the reaction system is high, and the required flow velocity of the inert gas is also high, which easily causes turbulence of the gas flow in the reaction system, and further causes melt splashing, and affects the purity of the magnesium metal vapor.
According to another embodiment of the invention, the temperature of the melting treatment can be 1300-1500 ℃, and the inventor finds that if the temperature of the melting treatment is too low, the raw materials are not easy to melt, the reduction reaction is slow, the melt is easy to cool, and if the temperature of the melting treatment is too high, the energy consumption of the system is high.
According to another embodiment of the invention, the melting treatment can be carried out in an induction furnace arranged in a closed chamber, the pressure in the closed chamber can be greater than the pressure in the induction furnace, so that the pollution to the environment is low, the noise is low, the field operation environment is obviously improved, the heat loss can be further reduced, a smelting pool can be directly formed in the induction furnace, and in addition, the reaction materials, the melt and the slag in the induction furnace can be effectively prevented from overflowing due to the fact that the pressure in the closed chamber is greater than the pressure in the induction furnace. Further, the pressure in the induction furnace can be 0.1-0.2 MPa, such as 0.1-0.12 MPa, the pressure in the closed chamber can be 0.15-0.3 MPa, such as 0.11-0.13 MPa, and particularly, inert gas flows filled in the induction furnace and the closed chamber can be respectively controlled to adjust, so that not only can the reaction materials, the melt and the slag in the induction furnace be prevented from overflowing, but also the energy power consumption of the system can be further reduced, and the magnesium metal oxidation caused by the fact that air leakage enters the system can be prevented.
According to another embodiment of the present invention, the inner lining of the induction furnace may be a graphite refractory material, the secondary outer layer may be a magnesium refractory material, the magnesium refractory material is wrapped around the inner lining of the graphite refractory material, and the outermost layer may be a metal shell, wherein the graphite refractory material is induced under the action of an induction electromagnetic field, and can generate heat and transfer heat by using the graphite refractory material, thereby further improving heat conduction efficiency, reducing heat loss, reducing erosion degree of the refractory material, and further improving the service life of the induction furnace.
According to another embodiment of the invention, the induction furnace and the closed chamber may be vacuumized and filled with inert gas before the melting process, and specifically, the induction furnace and the closed chamber may be vacuumized to 1000Pa in advance before the melting process, and then filled with inert gas to 0.1MPa, and the process is repeated twice to fully exhaust the residual air in the closed chamber, the induction furnace and the system pipeline; then, inert gas flows with specific flow rates into the induction furnace and the closed chamber respectively, so that the pressure in the induction furnace is 0.1-0.2 MPa, and the pressure in the closed chamber is 0.15-0.3 MPa, and the reduction reaction is promoted to be carried out smoothly.
According to another embodiment of the invention, the initial content of the reducing liquid can be 20-35% of the volume of the hearth of the induction furnace, and the inventor finds that if the initial content of the reducing liquid is smaller, a reducing agent needs to be continuously supplemented in the subsequent reduction treatment process, the system fluctuation is larger, the temperature in the smelting tank can be obviously reduced, the normal operation of the reduction treatment is influenced, and if the initial content of the reducing liquid is larger, the height occupied by slag in the hearth is higher, slag discharging treatment needs to be timely performed, the slag discharging frequency is higher, the magnesium purity is reduced due to easy splashing of the melt in the furnace, and the single-batch magnesium production rate is reduced. According to the invention, the initial content of the reducing liquid is controlled to be 20-35% of the volume of the hearth of the induction furnace, so that the continuous operation of the magnesium production process can be further facilitated, and the production efficiency and the magnesium liquid yield are improved.
According to another embodiment of the invention, the reducing agent and the fluxing agent can be respectively and independently fed into the induction furnace through the bins with the upper and lower double-bin structures, wherein the bins with the upper and lower double-bin structures can be connected with the vacuumizing device and the inert gas storage tank, so that air can be isolated and the pressure in the bins can be stabilized, thereby not only facilitating the addition of the reducing agent and the fluxing agent, but also further avoiding the subsequent combustion loss of magnesium vapor.
S200: blowing forging white or a mixture of the forging white and a fluxing agent into the reducing liquid for reduction treatment to obtain magnesium-containing flue gas, metal melt and smelting slag
According to the embodiment of the invention, the forging white or the mixture of the forging white and the fluxing agent is blown into the reducing liquid for reduction treatment so as to obtain magnesium-containing flue gas, metal melt and smelting slag, wherein the reduction treatment is also carried out in a closed environment under normal pressure or positive pressure, and the forging white or the mixture of the forging white and the fluxing agent can be directly added into the reducing liquid without transferring the reducing liquid. Therefore, the process flow can be shortened, the heat loss is greatly reduced, the heat utilization efficiency is obviously improved, continuous feeding and discharging can be realized, for example, a proper amount of reducing agent and fluxing agent can be supplemented periodically in the reduction treatment process, the metal melt and the smelting slag are discharged in time, the continuous production of the metal magnesium is realized, and the utilization rate of raw materials, the production efficiency and the metal recovery rate are obviously improved.
According to an embodiment of the invention, the forging white is obtained by calcining dolomite at 800-850 ℃ for 1.5-3 h, wherein the grain size of the forging white can be not more than 1mm, the grain size of the fluxing agent can be not more than 1mm, and further, the preferable grain size of the two blowing powders is not less than 90 wt% of the part with the grain size not more than 75 μm. This further contributes to an increase in the contact area between the forging cake and the reducing solution, thereby further increasing the reduction rate and the reduction effect.
According to still another embodiment of the present invention, the pressure condition and atmosphere for controlling the reduction treatment may be the same as those of the melting treatment, i.e., the reduction treatment may be performed in an inert atmosphere of 0.1 to 0.3MPa, for example, 0.1 to 0.15MPa, thereby not only ensuring the stability of the system, avoiding disturbance of the gas flow in the reaction system and smooth the reduction treatment, but also avoiding contact combustion of magnesium vapor and oxygen, thereby further improving the recovery rate and quality of magnesium.
According to another embodiment of the invention, the temperature of the reduction treatment can be 1300-1500 ℃, and the forging white is directly sprayed into the reducing liquid under a closed condition, so that the transfer of the reducing liquid and the inherent heat loss of equipment are remarkably reduced, and the smelting slag can also play a certain heat preservation role on a melt, so that more heat can be used for the reduction reaction of the forging white; in addition, because the content of the reducing solution is relatively high, the metallic iron and the like in the reducing solution can also be used as a high-temperature catalyst to further improve the reduction reaction rate, so that the reduction treatment can be smoothly carried out under the conditions of normal pressure or positive pressure and the temperature of 1300-1500 ℃.
According to another embodiment of the invention, reducing agent and/or fluxing agent can be further supplemented into the reducing liquid in the reduction treatment process, the content of active ingredients in the reducing liquid is continuously reduced along with the reduction reaction, the production rate of the magnesium metal is reduced, at the moment, the reducing agent can be supplemented into the furnace, the content of the active ingredients of the reducing agent in the molten pool is improved, and therefore, the continuous production of the magnesium metal can be further realized.
According to another embodiment of the invention, during the reduction treatment, the power of the induction furnace can be increased or decreased in time according to the temperature change in the furnace, and the temperature in the furnace is maintained at 1400-1500 ℃, thereby being further beneficial to the stable reduction treatment.
According to another embodiment of the invention, at least one of bottom blowing, side blowing and top blowing can be adopted to blow the calcined dolomite or the mixture of the calcined dolomite and the fluxing agent into the reducing liquid, so that the calcined dolomite and the reducing liquid can be further favorably and fully mixed, MgO in the calcined dolomite fully reacts with the reducing liquid to generate metal Mg, and the metal Mg enters the upper space of the induction furnace along with argon flow after being heated and gasified, is discharged from a pipeline and enters a condensing device, and is finally cooled into liquid magnesium. In addition, if a side-blowing and/or bottom-blowing mode is adopted, inert gas flow can be always sprayed into the spray gun from the beginning of the melting reaction to the end of the reduction reaction, so that the reduction liquid and/or the metal melt are prevented from flowing back to block the gun mouth.
According to another embodiment of the invention, the forged white or the mixture of the forged white and the fluxing agent can be blown into the reducing liquid by taking inert gas as a blowing carrier, and the gas-solid mass ratio of blowing can be 1: (10 to 100), the inventor finds that if the gas-solid mass ratio of the blowing gas is too large, the forging blank is not in full contact with the reducing liquid, the reducing rate and the reducing effect are influenced, and if the gas-solid mass ratio of the blowing gas is too small, the forging blank supplied into the reducing liquid in unit time is less, the reducing efficiency is also influenced, and the flow velocity of the inert gas flow is relatively high during the blowing, and the disturbance on the melt is large. By using inert gas as an injection carrier, the smelting system can be ensured to be in a non-oxidation environment, the combustion loss of magnesium steam generated by reduction is avoided, and the metal melt can have a moderate stirring effect, so that the reduction efficiency and the reduction effect of the forging white can be further improved, and the production efficiency and the recovery rate of magnesium are improved.
According to another embodiment of the invention, the content of the reducing liquid and/or the metal melt can be not less than 10-20% of the volume of the hearth of the induction furnace, after the smelting slag or the metal melt in the furnace are accumulated to a certain depth respectively, the smelting slag outlet or the melt outlet can be opened at random, the smelting slag and the metal melt in the furnace are discharged, but the reducing liquid and/or the metal melt with the volume of 10-20% of the hearth can be kept in the furnace, so that on one hand, the melting speed of the solid raw material loaded into the furnace can be increased, the heating efficiency and the heating speed of the induction furnace can be improved, on the other hand, the metal such as iron in the reducing liquid and/or the metal melt can be used as a high-temperature catalyst, the MgO reduction reaction speed can be further accelerated.
According to another embodiment of the invention, the content of the metal melt can be not higher than 50% of the depth of the hearth of the induction furnace, in order to avoid overflowing of smelting slag and the like in the furnace and enable smooth feeding of the reducing agent and/or the fluxing agent, when the content of the metal melt is higher than 50% of the depth of the hearth of the induction furnace, the smelting slag and the metal melt can be discharged in time, wherein the metal melt can be sold as an alloy, and can also be smelted into the reducing agent in the submerged arc furnace again to be used in the preparation process of magnesium.
According to another embodiment of the invention, the forge piece can be fed into the induction furnace by adopting a storage bin with an upper and lower double-bin structure, and the storage bin can be connected with a vacuumizing device and an inert gas storage tank, so that air can be isolated and the pressure in the storage bin can be stabilized, thereby not only facilitating the addition of the forge piece, but also further avoiding the combustion loss of magnesium steam caused by introducing air into the system.
S300: condensing the magnesium-containing flue gas to obtain magnesium metal liquid and magnesium-removed flue gas
According to the embodiment of the invention, the magnesium-containing flue gas is subjected to condensation treatment, so that the magnesium metal liquid and the magnesium-removed flue gas can be obtained. The temperature of the magnesium-removed flue gas can reach 700-750 ℃, so that the magnesium-removed flue gas can be further subjected to heat exchange, dust removal and drying treatment, the components of the flue gas subjected to the heat exchange, dust removal and drying treatment are inert gases, the inert gases can be directly discharged to the air or used as a blowing carrier for forging, when the inert gases are used as the blowing carrier, the inert gases can be vacuumized for a plurality of times in advance, after residual air in the whole system is exhausted, the flue gas subjected to the drying treatment is pressurized by a supercharger, then the flue gas is filled into an inert gas storage tank, and then the flue gas is used as the blowing carrier for forging.
According to a specific embodiment of the invention, impurities separated out from the magnesium liquid can be returned to the reduction treatment process for continuous reaction, and other solid impurities in the magnesium-containing flue gas can be supplemented by the magnesium liquid, so that the impurities can be automatically separated from the magnesium liquid due to density and property differences, the impurities in the tank can be irregularly cleaned, and the impurities with high magnesium content can be returned to the reduction treatment process for re-smelting.
According to another embodiment of the invention, the ferrosilicon with the Si content of not less than 75% can be crushed into blocks with the particle size of 5-50 mm, the flux can be crushed and sieved into particles with the particle size of 0.1-30 mm, for example, 5-30 mm, and the particles can be placed in a bin at the top of the furnace, the reducing agent bin and the flux can be sealed by adopting an upper bin and a lower bin structure, and the bin can be provided with a vacuumizing inlet and an argon filling inlet to isolate air and stabilize the pressure in the bin. Adding the ferrosilicon alloy into an induction furnace, heating and melting the ferrosilicon alloy into a liquid state, and controlling the temperature of the ferrosilicon alloy at 1400-1500 ℃. The inner lining of the induction furnace is made of graphite refractory materials, the secondary outer layer is made of magnesium refractory materials, the secondary outer layer is wrapped by the graphite refractory materials, the outermost layer is a metal shell, and the whole heating furnace body is arranged in the closed chamber. The sealed chamber and the induction furnace are both provided with an air exhaust inlet and an argon inlet, the furnace body is filled with argon flow when running, and the gas pressure in the sealed chamber is larger than that in the induction furnace. The graphite refractory material generates induction heat under the action of an induction electromagnetic field, and heats ferrosilicon alloy in the melting furnace to form an alloy molten pool in the furnace, wherein the molten pool accounts for about 20-35% of the capacity of the hearth of the induction furnace.
Furthermore, before smelting production, residual air in the furnace and in the pipeline is reduced to the maximum extent by means of vacuumizing and injecting argon into the system for multiple times, and oxidation and combustion of subsequent reduced magnesium metal steam are prevented. Treat in the system that inert gas pressure is stable and ferrosilicon melts the back, utilize argon gas as the carrier gas, spout the burnt lime powder material into the ferrosilicon molten bath in the stove, the jetting gas-solid mass ratio can be 1: (10-100). MgO in the calcined white powder and Si in the ferrosilicon liquid are subjected to reduction reaction to generate metal Mg, the metal Mg is heated and gasified, then enters the upper space of the induction furnace along with argon flow, is discharged from a pipeline and enters a condensing device, is finally cooled into liquid magnesium and is stored in a tank, the periphery of a magnesium liquid storage tank is wrapped with a heat insulation material, and the liquid magnesium in the tank is discharged out of an ingot at regular intervals. As the Si element in the ferrosilicon is consumed by the reduction reaction, the Si content in the reducing agent is continuously reduced, the ferrosilicon alloy liquid gradually becomes silicon-poor molten iron, and the production rate of the magnesium metal is also reduced. At this time, the ferrosilicon alloy can be added into the furnace to increase the Si content in the molten pool. When the silicon-poor molten iron in the furnace is accumulated to more than 50% of the depth of the molten pool, the melt outlet of the furnace body can be opened, the silicon-poor molten iron is discharged to a ladle, the silicon-poor molten iron can be sold as low-silicon ferroalloy, and can also be smelted into high-silicon ferroalloy in an ore smelting furnace againReturning to magnesium smelting. In addition, in the induction furnace, the ferrosilicon liquid with 10-20% of the volume of the hearth contained in the furnace can be always kept as a bottom molten pool, so that the melting speed of solid raw materials loaded in the furnace is increased, the MgO reduction reaction rate is promoted, and the production rate of magnesium metal is increased. SiO produced by magnesium reduction2Reacting with CaO in calcined dolomite to generate calcium silicate slag, and melting into liquid slag under the action of a fluxing agent added into the furnace. After liquid slag accumulates to a certain depth in the furnace, a smelting slag outlet is opened, the liquid slag is discharged into a slag basin under the siphon action, and the reducing slag is sold for producing building materials. After magnesium vapor is liquefied and collected, residual flue gas is pressurized again and sent into an argon storage tank after being cooled, dedusted and dried, and then returned to a smelting system for recycling. When the gas pressure in the argon storage tank is reduced, pure argon gas can be supplemented to the argon storage tank, and the pressure of the argon storage tank is kept stable.
In summary, the method for preparing magnesium metal according to the above embodiment of the present invention has at least the following advantages: 1. compared with the existing vacuum reduction magnesium preparation process, the method is carried out under normal pressure or positive pressure, vacuum operation is not needed, the burden of a vacuum system is small, and energy and power consumption is low; 2. the smelting process is carried out in a closed environment, so that the environmental pollution is low, the noise is low, and the field operation environment is obviously improved; 3. the melting treatment and the reduction treatment can be carried out in one reaction furnace without melt transfer, thereby not only shortening the process flow, but also greatly reducing the heat loss and obviously improving the heat utilization efficiency; 4. continuous feeding and discharging can be realized, the continuous production of the metal magnesium is realized, and the utilization rate of raw materials, the production efficiency and the metal recovery rate are high; 5. the production system can be simplified and the production cost can be significantly reduced.
According to a second aspect of the invention, the invention proposes a system for implementing the above method for producing magnesium metal. According to an embodiment of the present invention, as shown in fig. 1, the system includes: a closed chamber 100, an induction furnace 200, and a condensing unit 300. The system for preparing magnesium metal is described in detail below with reference to fig. 2 to 4.
Sealed chamber 100
According to the embodiment of the present invention, the first inert gas inlet 110 is provided on the closed chamber, wherein the closed chamber is adapted to seal the induction furnace and the operation area thereof, thereby not only reducing noise and environmental pollution in the magnesium manufacturing process, significantly improving the field operation environment, but also further reducing the heat loss of the whole operation system; in addition, the inert gas inlet is arranged on the closed chamber, and the residual air in the closed chamber can be discharged by injecting inert gas flow and the closed chamber can be controlled to be in a normal pressure or positive pressure environment.
According to an embodiment of the present invention, the wall of the closed chamber 100 may be provided with an insulating layer (not shown), wherein the insulating layer may be disposed on the inner surface and the outer surface of the wall of the closed chamber, or a cavity is formed in the wall to form an insulating interlayer, thereby further reducing heat loss during the magnesium smelting process and improving heat utilization rate.
Electric induction furnace 200
According to the embodiment of the invention, the electric induction furnace 200 is arranged in the closed chamber 100, the electric induction furnace comprises a furnace shell 210, a heating device 220, a furnace shell lining 230 and a spray gun 240, the electric induction furnace 200 is provided with a particle material inlet 251, a powder material inlet 252, a second inert gas inlet 253, a smoke gas outlet 254, a smelting slag outlet 255 and a melt outlet 256 which penetrate through the closed chamber, the heating device 230 is arranged in the furnace shell 210, the spray gun 240 penetrates through the closed chamber 100 and is inserted into the powder material inlet 252, a smoke exhaust area 260 and a smelting area 270 which are distributed up and down are defined in a hearth of the electric induction furnace 200, and a slag layer area 271 and a melt layer area 272 which are distributed up and down are defined in the smelting area 270. The reducing agent can be added through the particle material inlet, the forge welding is blown to the induction furnace through the spray gun, the inert gas is injected into the closed chamber through the inert gas inlet to discharge residual air in the induction furnace and control the pressure in the induction furnace, the induction furnace is suitable for forming a smelting region in a hearth, the reducing agent or the mixture of the reducing agent and the fluxing agent is subjected to melting treatment under normal pressure or positive pressure to obtain reducing liquid, the forge welding or the mixture of the forge welding and the fluxing agent is blown to the reducing liquid to be subjected to reducing treatment to obtain magnesium-containing flue gas, molten metal and smelting slag, the melting of the reducing agent and the reduction of the forge welding can be realized only by the induction furnace without other smelting equipment, so that the process flow can be shortened, the heat loss is greatly reduced, continuous feeding and discharging can be realized, the continuous production of magnesium metal is realized, the utilization rate of raw materials is remarkably, High production efficiency and metal recovery rate.
According to an embodiment of the present invention, the system for preparing magnesium metal may further include: the first vacuum apparatus 400, as shown in fig. 2 or 3, the first vacuum apparatus 400 may be connected to the hermetic chamber 100 and/or the induction furnace 200. Therefore, the induction furnace and the closed chamber can be vacuumized and filled with inert gas for treatment in advance before the melting treatment and the reduction treatment, specifically, the induction furnace and the closed chamber can be vacuumized to 1000Pa in advance before the melting treatment, then the inert gas is filled to 0.1MPa, and the steps are repeated twice, so that residual air in the closed chamber, the induction furnace and a system pipeline is fully discharged; then the inert gas flow with specific flow velocity in the induction furnace and the closed chamber is respectively carried out to respectively control the pressure in the induction furnace and the closed chamber and promote the reduction reaction to be smoothly carried out.
According to another embodiment of the present invention, the melting process can be performed under an inert atmosphere of 0.1 to 0.3MPa, for example, 0.1 to 0.15MPa, and the inventors found that, if the reaction pressure is too high, not only energy power consumption is large, but also the requirement for the tightness of the reaction system is high, and the required flow velocity of the inert gas is also high, which easily causes turbulence of the gas flow in the reaction system, and thus easily causes melt splash, and affects the purity of the magnesium metal vapor.
According to another embodiment of the present invention, the pressure inside the sealed chamber 100 may be greater than the pressure inside the induction furnace 200, thereby effectively preventing the reaction materials, the melt and the slag inside the induction furnace from overflowing. Further, the pressure in the induction furnace can be 0.1-0.2 MPa, such as 0.1-0.15 MPa, the pressure in the closed chamber can be 0.15-0.3 MPa, such as 0.15-0.3 MPa, and particularly, the inert gas flow filled in the induction furnace and the closed chamber can be respectively controlled to be adjusted, so that not only can the reaction materials, the melt and the slag in the induction furnace be prevented from overflowing, but also the energy power consumption of the system can be further reduced, and the magnesium metal oxidation caused by the fact that air leakage enters the system can be prevented.
According to another embodiment of the present invention, the furnace shell 210 may further include a metal shell and a secondary outer layer, the secondary outer layer may be a magnesium refractory layer, the furnace shell lining 230 may be a graphite refractory layer, and the graphite refractory generates induction heat under the action of the induction electromagnetic field, so that not only the service life of the induction furnace can be prolonged, but also the graphite refractory can be utilized to generate heat and transfer heat, thereby further improving the heat conduction efficiency, reducing the heat loss, reducing the erosion degree of the refractory, and further prolonging the service life of the induction furnace.
According to another embodiment of the present invention, as shown in fig. 3 or fig. 4, the powder inlet 252 may be disposed at the bottom and/or the side and/or the top of the induction furnace 200, so that the white forging or the mixture of the white forging and the flux may be injected into the reducing liquid by at least one of bottom blowing, side blowing and top blowing, thereby further facilitating the sufficient mixing of the white forging and the reducing liquid, improving the reduction efficiency, allowing the MgO in the white forging to fully react with the reducing liquid and generate the metal Mg, and after the metal Mg is heated and gasified, the metal Mg enters the upper space of the induction furnace along with the argon gas flow, and is discharged from the pipe and enters the condensing device, and finally cooled to be liquid magnesium. In addition, if the powder inlet 252 is disposed at the bottom and/or the side of the electric induction furnace 200, an inert gas flow can be injected into the lance from the beginning of the melting reaction to the end of the reduction reaction, thereby preventing the reduction solution and/or the metal melt from flowing back to block the mouth of the lance.
According to another embodiment of the present invention, when the powder inlet 252 is disposed at the bottom and/or the top of the electric induction furnace 200, the lance 240 may be inserted into the powder inlet perpendicularly to the horizontal direction, and when the powder inlet 252 is disposed at the side of the electric induction furnace 200, the included angle between the lance 240 and the horizontal direction may be not more than 10 degrees.
According to another embodiment of the present invention, the melt zone 272 may be not more than 50% of the depth of the hearth of the induction furnace, and in order to prevent the overflow of the slag and the like in the furnace and to make the feeding of the reducing agent and/or the fluxing agent smooth, when the content of the metal melt is higher than 50% of the depth of the hearth of the induction furnace, the smelting slag and the metal melt can be discharged in time, wherein the metal melt can be sold as an alloy or smelted into the reducing agent in the submerged arc furnace again for being used in the magnesium preparation process. Furthermore, the content of the melt zone is not lower than 10-20% of the volume of the hearth of the induction furnace, after the smelting slag or the metal melt in the furnace are accumulated to a certain depth respectively, a smelting slag outlet or a melt outlet can be opened at random to discharge the smelting slag and the metal melt in the furnace, but the reducing liquid and/or the metal melt with the volume of 10-20% of the hearth can be kept in the furnace, so that on one hand, the melting speed of the solid raw material loaded in the furnace can be accelerated, the heating efficiency and the heating speed of the induction furnace are improved, on the other hand, the metal such as iron in the reducing liquid and/or the metal melt can be used as a high-temperature catalyst, the MgO reduction reaction speed is further promoted, and the production speed.
According to another embodiment of the present invention, as shown in fig. 3 or 4, the particulate material inlet 251 may be connected to the reducing agent bin 610, the injection lance 240 may be connected to the forge material bin 620, the particulate material inlet 251 and/or the injection lance 240 may be connected to the flux bin 630, and the reducing agent bin 610, the flux bin 630 and the forge material bin 620 may be independently constructed in an upper and lower double bin structure, respectively, thereby being more advantageous in isolating air and preventing air from being introduced into the induction furnace during charging. Further, the reducing agent bin 610, the flux bin 630 and the forging white bin 620 can be independently connected with the first vacuumizing device 400 and the inert gas storage tank respectively, so that residual air in the bins can be further exhausted through vacuumizing and injecting inert gas, the air is isolated, the pressure in the bins is stabilized, the addition of the reducing agent and the flux is facilitated, and the subsequent combustion loss of magnesium vapor can be further avoided.
According to still another embodiment of the present invention, the reducing agent bin 610, the flux bin 630 and the forging white bin 620 may be independently provided with a feeding valve and a doser (not labeled), respectively, whereby it may be more advantageous to precisely control the amount of the raw materials to be added.
According to another embodiment of the present invention, the types of the reducing agent and the fluxing agent in the present invention are not particularly limited, and can be selected by those skilled in the art according to actual needs. For example, the reducing agent may be at least one selected from the group consisting of a silicon-iron alloy, a silicon-calcium alloy, a silicon-manganese alloy, metallic aluminum, and metallic calcium, and the flux may be at least one selected from the group consisting of fluorite, potassium fluoride, and sodium fluoride, wherein the silicon-iron alloy has an Si content of not less than 75%. Furthermore, the reducing agent and the fluxing agent may be crushed and sieved in advance before the step (1), wherein the particle size of the reducing agent may be 20 to 50mm, and the particle size of the fluxing agent may be 0.1 to 30mm, for example, 5 to 30mm, and the like, thereby further improving the melting efficiency and the raw material utilization rate. In addition, the forging white is obtained by calcining dolomite at 800-850 ℃ for 1.5-3 h, wherein the grain size of the forging white can be not more than 1mm, the grain size of the fluxing agent can be not more than 1mm, and furthermore, the part of the two injection powder with the grain size of not more than 75 mu m is not less than 90 wt%. This further contributes to an increase in the contact area between the forging cake and the reducing solution, thereby further increasing the reduction rate and the reduction effect.
According to another embodiment of the invention, the temperature of the melting treatment can be 1300-1500 ℃, and the inventor finds that if the temperature of the melting treatment is too low, the raw materials are not easy to melt, the reduction reaction is slow, the melt is easy to cool, and if the temperature of the melting treatment is too high, the energy consumption of the system is high.
According to another embodiment of the invention, the initial content of the reducing liquid can be 20-35% of the volume of the hearth of the induction furnace, and the inventor finds that if the initial content of the reducing liquid is smaller, a reducing agent needs to be continuously supplemented in the subsequent reduction treatment process, the system fluctuation is larger, the temperature in the smelting tank can be obviously reduced, the normal operation of the reduction treatment is influenced, and if the initial content of the reducing liquid is larger, the height occupied by slag in the hearth is higher, slag discharging treatment needs to be timely performed, the slag discharging frequency is higher, the magnesium purity is reduced due to easy splashing of the melt in the furnace, and the single-batch magnesium production rate is reduced. According to the invention, the initial content of the reducing liquid is controlled to be 20-35% of the volume of the hearth of the induction furnace, so that the continuous operation of the magnesium production process can be further facilitated, and the production efficiency and the magnesium liquid yield are improved.
According to still another embodiment of the present invention, the pressure condition and atmosphere of the reduction treatment can be controlled to be the same as those of the melting treatment, thereby not only ensuring the stability of the system and preventing the turbulence of the gas flow in the reaction system to make the reduction treatment smoothly proceed, but also preventing the magnesium vapor from being burned in contact with oxygen, thereby further improving the recovery rate and quality of magnesium.
According to another embodiment of the invention, the temperature of the reduction treatment can be 1300-1500 ℃, and the forging white is directly sprayed into the reducing liquid under a closed condition, so that the transfer of the reducing liquid and the inherent heat loss of equipment are remarkably reduced, and the smelting slag can also play a certain heat preservation role on a melt, so that more heat can be used for the reduction reaction of the forging white; in addition, because the content of the reducing solution is relatively high, the metallic iron and the like in the reducing solution can also be used as a high-temperature catalyst to further improve the reduction reaction rate, so that the reduction treatment can be smoothly carried out under the conditions of normal pressure or positive pressure and the temperature of 1300-1500 ℃.
According to another embodiment of the invention, during the reduction treatment, the power of the induction furnace can be increased or decreased in time according to the temperature change in the furnace, and the temperature in the furnace is maintained at 1400-1550 ℃, thereby being further beneficial to the stable operation of the reduction treatment.
According to another embodiment of the invention, reducing agent and/or fluxing agent can be further supplemented into the reducing liquid in the reduction treatment process, the content of active ingredients in the reducing liquid is continuously reduced along with the reduction reaction, the production rate of the magnesium metal is reduced, at the moment, the reducing agent can be supplemented into the furnace, the content of the active ingredients of the reducing agent in the molten pool is improved, and therefore, the continuous production of the magnesium metal can be further realized.
According to another embodiment of the invention, the forged white or the mixture of the forged white and the fluxing agent can be blown into the reducing liquid by taking inert gas as a blowing carrier, and the gas-solid mass ratio of blowing can be 1: (10 to 100), the inventor finds that if the gas-solid mass ratio of the blowing gas is too large, the forging blank is not in full contact with the reducing liquid, the reducing rate and the reducing effect are influenced, and if the gas-solid mass ratio of the blowing gas is too small, the forging blank supplied into the reducing liquid in unit time is less, the reducing efficiency is also influenced, and the flow velocity of the inert gas flow is relatively high during the blowing, and the disturbance on the melt is large. By using inert gas as an injection carrier, the smelting system can be ensured to be in a non-oxidation environment, the combustion loss of magnesium steam generated by reduction is avoided, and the metal melt can have a moderate stirring effect, so that the reduction efficiency and the reduction effect of the forging white can be further improved, and the production efficiency and the recovery rate of magnesium are improved.
Condensing unit 300
According to the embodiment of the invention, the condensing device 300 comprises a condenser 310 and a magnesium liquid storage tank 320 which are arranged in an up-and-down communication mode, wherein the condenser is provided with a flue gas inlet 311 and a magnesium-removing flue gas outlet 312, the magnesium liquid storage tank is provided with a magnesium liquid outlet 321 and an impurity outlet 322, and the flue gas inlet 311 is connected with the flue gas outlet 254. Wherein, the condensing unit is suitable for carrying out condensation treatment on the magnesium-containing flue gas to obtain the metal magnesium liquid and the magnesium-removed flue gas.
According to an embodiment of the present invention, as shown in fig. 4, the side and/or bottom of the magnesium liquid storage tank 320 may be provided with an insulating layer 330, so that heat loss of the molten magnesium can be reduced, thereby facilitating ingot casting.
According to still another embodiment of the present invention, as shown in fig. 3 and 4, the system for preparing magnesium metal may further include: the dust removal device 710 and the drying device 720, wherein the dust removal device 710 is connected with the magnesium removal flue gas outlet 312; the air inlet of the drying device 720 is connected with the dust removing device 710, and the air outlet of the drying device 720 is connected with the air emptying device 800 and/or the spray gun 240; further, a heat exchange device 730 can be further arranged between the dust removing device 710 and the magnesium removing flue gas outlet 312. Therefore, the magnesium-removing flue gas can be directly discharged to the air after heat exchange, dust removal and drying, or can be used as a forged blowing carrier.
According to another embodiment of the present invention, as shown in fig. 3 or fig. 4, a booster 910 and an inert gas storage tank 920 may be disposed between the outlet of the drying device 720 and the spray gun 240, which are connected in sequence, and a second vacuum-pumping device 500 may be disposed between the outlet of the drying device 720 and the gas venting device 800. Specifically, the gas outlet pipeline of the drying device 720 may include three branches, wherein the first branch 721 is sequentially connected to the supercharger 910 and the inert gas storage tank 920, the first branch is provided with a first vent valve 724, the second branch 722 and the third branch 723 are connected to the evacuation device 800, the second vent valve 725 is provided at the upstream of the second branch 722 and the third branch 723, the second branch 722 is provided with a third vent valve 726, and the third branch 723 is provided with the second vacuum-pumping device 500. Therefore, when the magnesium-removed flue gas after heat exchange, dust removal and drying is directly discharged to the air, the first vent valve 724 and the second vacuumizing device 500 can be closed, and the second vent valve 725 and the third vent valve 726 can be opened at the same time; when the magnesium-removed flue gas after heat exchange, dust removal and drying is used as an injection carrier, the first vent valve 724 and the third vent valve 726 can be closed in advance, the second vent valve 725 and the second vacuumizing device 500 are opened simultaneously, the gas transmission pipeline and the system of the whole system are vacuumized, air residual in the system is avoided, the second vent valve 725 and the second vacuumizing device 500 are closed after vacuumizing is completed, the first vent valve 724 and the supercharger 910 are opened simultaneously, the dried flue gas is pressurized and then filled into an inert gas storage tank, and the inert gas storage tank is further used for injecting the carrier.
According to still another embodiment of the present invention, the first and second vacuum evacuation apparatuses 400 and 500 may respectively and independently include one or more vacuum pumps, wherein, as shown in fig. 2 and 3, the first vacuum evacuation apparatus 400 may include at least two vacuum pumps 410, thereby respectively evacuating and ventilating each of the silo, the enclosed chamber, and the induction furnace.
According to a specific embodiment of the invention, impurities separated out from the magnesium liquid can be returned to the reduction treatment process for continuous reaction, and other solid impurities in the magnesium-containing flue gas can be supplemented by the magnesium liquid, so that the impurities can be automatically separated from the magnesium liquid due to density and property differences, the impurities in the tank can be irregularly cleaned, and the impurities with high magnesium content can be returned to the reduction treatment process for re-smelting.
In summary, the system for preparing magnesium metal according to the above embodiment of the present invention has at least the following advantages: 1. the system has simple structure and low cost, does not need to be provided with a vacuum tank and only has one smelting furnace, has low energy and power consumption in the reaction process, does not need melt transfer, and obviously reduces the heat loss; 2. the system has high automation degree and good tightness, and the induction furnace is arranged in the closed chamber, so that the environmental pollution and noise in the smelting process can be obviously reduced, the production environment is improved, and the heat loss can be further reduced; 3. continuous feeding and discharging can be realized, continuous production of metal magnesium is realized under normal pressure or positive pressure, and the production efficiency, the raw material utilization rate and the metal recovery rate are improved; 4. the smelting process can be carried out in an inert atmosphere, and magnesium steam can be effectively prevented from burning, so that the recovery rate of magnesium is further improved.
The scheme of the invention will be explained with reference to the examples. It will be appreciated by those skilled in the art that the following examples are illustrative of the invention only and should not be taken as limiting the scope of the invention. The examples, where specific techniques or conditions are not indicated, are to be construed according to the techniques or conditions described in the literature in the art or according to the product specifications. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products commercially available.
Example 1
Preparation stage
Preparing raw materials: the method comprises the following steps of heating dolomite in a rotary kiln to 800-850 ℃, keeping the temperature within the temperature range for 2 hours, directly discharging the dolomite for calcination to obtain calcined dolomite (calcined dolomite for short), and loading the calcined dolomite into a calcined dolomite bin after the ball milling particle size is smaller than 200 meshes. 75 ferrosilicon and fluorite are crushed into blocks with the grain size not less than 20mm, and the blocks are respectively filled into a reducing agent bin and a fluxing agent bin at the top of the furnace.
And (3) system exhaust: pumping the induction furnace, the closed chamber, a follow-up flue, a condensation system and the like to a vacuum degree of 1000Pa, closing the vacuum system, opening an argon gas charging system, introducing argon gas into the induction furnace and the closed chamber, closing the argon gas system after the gas pressure in the induction furnace reaches the normal pressure of 0.1MPa, and opening the vacuum system. Repeating the above steps for 2 times to fully discharge residual air in the induction furnace, the sealed chamber and the subsequent system. And finally, continuously introducing argon flow into the furnace, and maintaining the gas pressure in the furnace at 0.1-0.12 MPa and the pressure in the closed chamber at 0.11-0.13 MPa.
(II) melting treatment
In the exhaust process of the system, ferrosilicon and fluxing agent are added into the induction furnace, the induction furnace is electrified and heated, the temperature of the ferrosilicon in the induction furnace is gradually raised, the ferrosilicon in the induction furnace is gradually melted into liquid after reaching 1500 ℃, a reducing agent molten pool is formed in the induction furnace, and the depth of the molten pool is about 25 percent of the depth of a hearth. During the process of making a molten pool, argon flow is always sprayed into the spray gun to prevent liquid in the molten pool from flowing back to block a gun mouth.
(III) reduction treatment and condensation treatment
After a molten pool in the induction furnace is formed and exhaust is finished, a calcined dolomite bin valve is opened, and the powdery calcined dolomite is blown into the molten pool in the furnace under the driving of argon gas flow blowing. The magnesium vapor is continuously reduced out and enters a condensing device with the temperature maintained at 700-750 ℃ under the drive of argon flow, and is continuously condensed into magnesium metal liquid. And the residual flue gas is injected into an argon storage tank after being cooled, dedusted, dehydrated and pressurized, and then is recycled by the induction furnace system.
And replenishing ferrosilicon alloy and fluxing agent into the furnace at proper time according to the reaction rate of magnesium vapor in the furnace, the condensation amount of magnesium liquid and the slag melting condition. And (3) increasing and decreasing the power of the induction furnace in due time according to the temperature change in the furnace, and keeping the temperature in the furnace at 1400-1500 ℃. And after the slag or the silicon-poor molten iron in the furnace are accumulated to a certain depth respectively, opening a slag outlet or a melt outlet at random, discharging the slag in the furnace to a slag ladle outside the furnace, and discharging the silicon-poor molten iron in the furnace to a ladle outside the furnace, wherein a molten iron melting pool which accounts for about 10-15% of the capacity of the furnace is still kept in the furnace. The waste slag discharged out of the furnace is sold for building material production, and the silicon-poor molten iron is sold as low-silicon ferroalloy for manufacturing alloy steel.
In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.
Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.

Claims (10)

1. A method of producing magnesium metal, comprising:
(1) carrying out melting treatment on a reducing agent or a mixture of the reducing agent and a fluxing agent so as to obtain a reducing liquid;
(2) blowing forging white or a mixture of the forging white and a fluxing agent into the reducing liquid for reduction treatment so as to obtain magnesium-containing flue gas, metal melt and smelting slag;
(3) condensing the magnesium-containing flue gas to obtain magnesium metal liquid and magnesium-removed flue gas,
wherein the steps (1) to (2) are carried out in a closed environment under normal pressure or positive pressure.
2. The method of claim 1, further comprising:
(4) and (3) performing dust removal and drying treatment on the magnesium-removed flue gas, and then recycling the magnesium-removed flue gas as a blowing carrier in the step (2).
3. The method according to claim 1 or 2, wherein the steps (1) to (2) are carried out under an inert atmosphere of 0.1 to 0.3MPa,
optionally, in the step (1), the temperature of the melting treatment is 1300-1500 ℃,
optionally, the reducing agent is at least one selected from ferrosilicon, silico-calcium, silico-manganese, metallic aluminum and metallic calcium, the flux is at least one selected from fluorite, potassium fluoride and sodium fluoride,
optionally, the particle size of the reducing agent is 5-50 mm, and the particle size of the fluxing agent is 0.1-30 mm.
4. The method according to claim 3, wherein in the step (2), the temperature of the reduction treatment is 1300 to 1500 ℃,
optionally, step (2) further comprises: replenishing reducing agent and/or fluxing agent into the reducing solution,
optionally, in step (2), the blowing manner comprises at least one of bottom blowing, side blowing and top blowing,
optionally, in the step (2), an inert gas is used as a blowing carrier to blow the forged blank or a mixture of the forged blank and a fluxing agent into the reducing liquid, wherein the blowing gas-solid mass ratio is 1: (10-100) of a first polymer,
optionally, in the step (2), the forged white is obtained by calcining dolomite at 800-850 ℃ for 1.5-3 h,
optionally, in the step (2), the forged steel sheet has a grain size of not more than 1mm, preferably a fraction having a grain size of not more than 75 μm of not less than 90 wt%; the flux has a particle size of not more than 1mm, and preferably a portion having a particle size of not more than 75 μm is not less than 90 wt%.
5. The method according to claim 1 or 4, wherein the steps (1) to (2) are performed in an induction furnace disposed in a closed chamber having a pressure greater than that in the induction furnace,
optionally, the pressure in the induction furnace is 0.1-0.2 MPa, the pressure in the closed chamber is 0.15-0.3 MPa,
optionally, the inner lining of the induction furnace is made of graphite refractory material, the secondary outer layer is made of magnesium refractory material, the outermost layer is made of metal shell,
optionally, the content of the reducing liquid and/or the metal melt is not less than 10-20% of the volume of the hearth of the induction furnace,
optionally, in the step (1), the initial content of the reducing liquid is 20-35% of the furnace chamber volume of the induction furnace,
optionally, in the step (2), the content of the metal melt is not higher than 50% of the hearth depth of the induction furnace,
optionally, the induction furnace and the closed chamber are subjected to a vacuum-pumping treatment and an inert gas-filling treatment in advance before the step (1) is performed.
6. A system for carrying out the method for producing metallic magnesium according to any one of claims 1 to 5, comprising:
the closed chamber is provided with a first inert gas inlet;
the induction furnace is arranged in the closed chamber and comprises a furnace shell, a heating device, a furnace shell lining and a spray gun, the induction furnace is provided with a particle material inlet, a powder material inlet, a second inert gas inlet, a smoke outlet, a smelting slag outlet and a melt outlet, the particle material inlet, the powder material inlet, the second inert gas inlet, the smoke outlet, the smelting slag outlet and the melt outlet penetrate through the closed chamber, the spray gun penetrates through the closed chamber and is inserted into the powder material inlet, a smoke exhaust area and a smelting area which are distributed up and down are defined in a hearth of the induction furnace, and a slag layer area and a melt area which are distributed up and down are defined in the smelting area;
the condensing equipment, condensing equipment includes condenser and the magnesium liquid storage tank that upper and lower intercommunication was arranged, the condenser has the flue gas entry and removes the magnesium exhanst gas outlet, the magnesium liquid storage tank has magnesium liquid export and impurity export, the flue gas entry with the flue gas outlet links to each other.
7. The system of claim 6, further comprising:
and the first vacuumizing device is connected with the closed chamber and/or the electric induction furnace.
8. The system of claim 6 or 7, further comprising:
the dust removal device is connected with the magnesium removal flue gas outlet;
a gas inlet of the drying device is connected with the dust removal device, a gas outlet of the drying device is connected with a gas emptying device and/or the spray gun,
optionally, a heat exchange device is arranged between the dust removal device and the magnesium removal flue gas outlet,
optionally, a supercharger and an inert gas storage tank which are connected in sequence are arranged between the gas outlet of the drying device and the spray gun, and a second vacuumizing device is arranged between the gas outlet of the drying device and the gas emptying device.
9. The system of claim 8, wherein the particulate material inlet is connected to a reducing agent bin, the lance is connected to a forge white bin, the particulate material inlet and/or the lance is connected to a flux bin, the reducing agent bin, the flux bin and the forge white bin are each independently an upper and lower double bin structure,
optionally, the reducing agent bin, the flux bin and the forge material bin are independently connected to a first vacuum device and the inert gas storage tank, respectively.
10. The system of claim 6 or 9, wherein the furnace shell further comprises a metal shell and a secondary outer layer, the secondary outer layer being a layer of magnesium refractory material, the furnace shell lining being a layer of graphite refractory material,
optionally, the powder inlet is arranged at the bottom and/or the side and/or the top of the induction furnace, the spray gun is inserted into the powder inlet from the bottom and/or the top of the induction furnace in a direction perpendicular to the horizontal direction, and/or is inserted into the powder inlet from the side of the induction furnace in a direction with an included angle of not more than 10 degrees with the horizontal direction,
optionally, the melt zone is not more than 50% of the hearth depth of the induction furnace,
optionally, the wall of the closed chamber is provided with an insulating layer,
optionally, the side and/or the bottom of the magnesium liquid storage tank is/are provided with an insulating layer.
CN202010084598.2A 2020-02-10 2020-02-10 Method and system for preparing magnesium metal Pending CN111321310A (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112501434A (en) * 2020-10-19 2021-03-16 北京中冶设备研究设计总院有限公司 Liquid magnesium smelting reducing agent and application thereof
CN114293014A (en) * 2021-12-16 2022-04-08 西安交通大学 Silicon carbide-free thermal reduction magnesium metallurgy device and method

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112501434A (en) * 2020-10-19 2021-03-16 北京中冶设备研究设计总院有限公司 Liquid magnesium smelting reducing agent and application thereof
CN114293014A (en) * 2021-12-16 2022-04-08 西安交通大学 Silicon carbide-free thermal reduction magnesium metallurgy device and method

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