Asynchronous indirect carbon thermal reduction magnesium smelting system based on double-liquid-phase catalysis

Abstract

The invention provides an asynchronous indirect carbon thermal reduction magnesium smelting system based on double-liquid-phase catalysis, which is characterized in that a double-liquid-phase system of a molten metal liquid and a molten slag phase is constructed by taking active metal dissolved in the molten metal liquid as an intermediate catalytic medium through a two-stage asynchronous alternating reaction of reducing agent regeneration and magnesium smelting, so that the mass transfer efficiency is improved; in the reducing agent regeneration stage, a carbonaceous reducing agent is added to reduce a slag phase to generate molten MX and discharge CO, and in the magnesium smelting stage, MX reduces MgO to generate magnesium steam, so that CO and magnesium steam do not meet to avoid reverse reaction, slag-free magnesium smelting is achieved with the low-cost carbonaceous reducing agent, the reverse reaction is avoided, the magnesium yield is increased, by-products CO and silicon resources can be recycled, and the production cost is reduced. Environmental protection, low cost and industrial feasibility are considered.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of metal magnesium production, in particular to a system for asynchronous indirect carbon thermal reduction of magnesium based on double-liquid-phase catalysis. BACKGROUND

[0002] Metal magnesium is a strategic metal with abundant reserves and sustainable use, and is the only metal resource that can be used for millions of years. It is widely used in the fields of aerospace, transportation, and electronic industry. At present, the mainstream technology of industrial magnesium production can be divided into three categories: The first is electrolysis method starting from seawater, salt brine or magnesite, which extracts metal magnesium through electrolysis system. However, electrolysis method has serious environmental and safety hazards. By-product chlorine gas has strong corrosive property, which not only corrodes production equipment and shortens service life, but also endangers the health of operators and causes serious air pollution. Its treatment cost is high and the effect is limited, which is difficult to meet the strict safety, environment and health (HSE) standards of contemporary society.

[0003] The second is the Pidgeon method using dolomite for magnesium production on land, which uses silicon iron as the core reducing agent to complete the reduction reaction. However, the resource waste and environmental pressure are prominent. For every 1 part of metal magnesium produced, more than 6 times the mass of fine dust waste is generated. The storage of such waste occupies a large amount of land and easily causes dust pollution, which has a long-term negative impact on the ecological environment and does not meet the green production concept. The third is the slag-free carbon thermal method suitable for seawater, salt brine and magnesite, which generates magnesium vapor through high-temperature reduction, and then obtains metal magnesium through condensation. However, the Mg vapor obtained by high-temperature reduction reaction will react with CO gas in the furnace gas during the cooling process, which greatly reduces the yield of metal magnesium and directly increases the production cost, limiting the large-scale application of this technology.

[0004] When the existing technology uses slag-free carbon thermal method, an ultrasonic nozzle is used as a quenching condenser. This method can indeed achieve rapid condensation of magnesium vapor and reduce the degree of reverse reaction. However, the supersonic jet flow requires a large pressure ratio before and after the nozzle, which means that the outlet of the nozzle must reach an extremely high vacuum degree. The CO gas finally discharged from the vacuum pump is a non-condensable gas, and its volume flow under high vacuum is a huge amount. In industrial production, a large number of large vacuum pumps need to be used in parallel, which is high in cost and energy consumption. SUMMARY

[0005] The present application provides a system for asynchronous indirect carbon thermal reduction of magnesium based on double-liquid-phase catalysis. Through the double-liquid-phase molten pool and the asynchronous reaction mechanism, slag-free magnesium production is realized with low-cost carbon reducing agent, the reverse reaction is avoided to improve the magnesium yield, and by-product CO and silicon resources can be recovered, which takes into account environmental protection, low cost and industrial feasibility.

[0006] In order to achieve the above object, the technical scheme provides a system for asynchronous indirect carbon thermal reduction of magnesium based on double-liquid-phase catalysis, comprising: a magnesium smelting electric arc furnace, wherein a double-liquid-phase molten pool formed by mixing of molten metal liquid and molten slag is arranged in the magnesium smelting electric arc furnace, the molten slag contains at least one metal oxide, the molten metal liquid contains a base metal liquid and a molten active metal, and the metal oxide and the active metal are of the same metal type, and the magnesium smelting electric arc furnace is used for alternately introducing carbonaceous reducing agent and magnesium oxide to switch between reducing agent regeneration stage and magnesium smelting stage; a heat supplement chamber communicated with a furnace gas outlet of the magnesium smelting electric arc furnace, used for maintaining or increasing the temperature of the furnace gas flowing out of the magnesium smelting electric arc furnace; a quenching condenser communicated with a high-temperature furnace gas channel of the heat supplement chamber, used for condensing the furnace gas generated in the reducing agent regeneration stage, and isentropically expanding and cooling the furnace gas generated in the magnesium smelting stage; a first cooling chamber connected with the quenching condenser, used for condensing the furnace gas generated in the reducing agent regeneration stage, and condensing the furnace gas generated in the magnesium smelting stage to obtain silicon oxide powder and crystalline magnesium powder; and a second cooling chamber connected with a gas channel of the first cooling chamber, used for condensing the furnace gas generated in the reducing agent regeneration stage, and further condensing the furnace gas generated in the magnesium smelting stage to obtain magnesium particles.

[0007] Compared with the prior art, the technical scheme has the following characteristics and beneficial effects: (1) The system for asynchronous indirect carbon thermal reduction of magnesium based on double-liquid-phase catalysis in the scheme only consumes carbonaceous reducing agent and magnesium oxide in the magnesium smelting production line, replaces the expensive ferrosilicon as reducing agent, greatly reduces the production cost, and almost does not produce process waste slag, realizing the slag-free thermal reduction of magnesium.

[0008] (2) The system for asynchronous indirect carbon thermal reduction of magnesium based on double-liquid-phase catalysis in the scheme almost does not have the biggest obstacle that the conventional carbon thermal reduction of magnesium must encounter, that is, the reverse reaction, because the CO gas and the magnesium vapor are alternately discharged in different time windows, the CO gas and the magnesium vapor flow in the same space in different time periods and do not have the opportunity to meet and react with each other, greatly improving the yield of magnesium.

[0009] (3) The magnesium vapor in the system for asynchronous indirect carbon thermal reduction of magnesium based on double-liquid-phase catalysis in the scheme can be condensed and collected in the form of liquid magnesium, avoiding the conventional carbon thermal reduction of magnesium in the form of powder, effectively avoiding the unsafe hidden danger of flammable and explosive magnesium powder, and being an intrinsically safe process technology route. BRIEF DESCRIPTION OF DRAWINGS

[0010] The drawings described herein are used to provide further understanding of the present application, and form a part of the present application. The schematic embodiments of the present application and the descriptions thereof are used to explain the present application, and do not constitute an improper limitation on the present application. In the drawings: Figure 1It is the overall structure schematic diagram of the system for indirect carbon thermal reduction of magnesium based on double-liquid-phase catalysis provided by the present scheme.

[0011] Figure 2 It is the schematic diagram of the principle of the process of indirect carbon thermal reduction of magnesium based on double-liquid-phase catalysis.

[0012] Figure 3 It is the schematic diagram of the structure of the magnesium smelting electric arc furnace.

[0013] Figure 4 It is the schematic diagram of the process of double-layer liquid-phase reduction in the furnace.

[0014] Figure 5 It is the schematic diagram of the connection structure of the heat supplementing chamber and the quenching condenser.

[0015] Figure 6 It is the top view of the connection of the quenching condenser and the first cooling chamber.

[0016] Figure 7 It is the schematic diagram of the first cooling chamber and the second cooling chamber.

[0017] Figure 8 It is the schematic diagram of the system in which the magnesium distillation furnace is located.

[0018] Figure 9 It is another overall structure schematic diagram of the system for indirect carbon thermal reduction of magnesium based on dolomite forging white provided by the present scheme.

[0019] Figure 10 It is the structural schematic diagram of the magnesium liquid condenser and the magnesium liquid surface adjusting chamber.

[0020] Figure 11 It is the schematic diagram of the magnesium liquid condenser and the magnesium liquid surface adjusting chamber from another perspective Figure 12 It is the top view of the magnesium liquid condenser.

[0021] Figure 13 It is the left view of the magnesium liquid condenser.

[0022] Fig. Arc furnace for magnesium smelting 101, steel shell of electric furnace 102, heat insulation layer 103, graphite furnace lining 104, hollow top electrode 105, bottom electrode 106, furnace gas outlet 107, slag channel 108, magnesium oxide powder tank 109, carbon powder tank 110, magnesium oxide powder submerged side blowing lance 115, carbon powder submerged side blowing lance 116, heat supplement chamber 120, heat supplement electrode anode 121, heat supplement electrode cathode 122, high temperature furnace gas passage 123, quenching condenser 201, tapered pipe 208, throat 209, expansion pipe 210, parallel pipe 211, first cooling chamber 301, one cooling on-off valve 302, one cooling shell evaporation pipe 303, one cooling upper evaporation heat exchanger 304, two cooling upper water cooling pipe 305, two cooling constant temperature water tank 306, two cooling cooling water inlet 307, two cooling cooling water outlet 308, magnesium-silicon binary mixed powder 309, second cooling chamber 310, two cooling on-off valve 311, dust collector 320, vacuum pump 321, by-product fuel gas storage tank 322, magnesium liquid condenser 401, magnesium liquid level adjusting chamber 402, bottom communication pipe 403, magnesium liquid discharge valve 405, magnesium liquid main pool 410, magnesium liquid auxiliary pool 411, medium temperature furnace gas exhaust pipe 420, low temperature furnace gas exhaust pipe 421, vacuum evaporation condenser 430, water inlet main pipe 431, water mist spray head 432, negative pressure pump 433, negative pressure steam delivery pipe 434, argon gas pressure tank 450, argon filling valve 451, argon filling pipeline 452, liquid level adjusting vacuum pump 453, exhaust valve 454, exhaust pipeline 455, liquid throwing flywheel set 460, argon gas protection solid powder briquetting machine 501, silicon-magnesium mixed material 507, magnesium metal remelting ingot casting machine 510, magnesium distillation furnace 601, heating chamber 602, distillation primary cooling chamber 603, distillation secondary cooling chamber 604, vacuum pump 605, primary cooling constant temperature cooling tank 606, secondary cooling constant temperature liquid tank 607, main crystalline magnesium 608, secondary crystalline magnesium 609, heat source inlet 620, waste heat source outlet 621, crystalline magnesium primary cooling coolant inlet 622, crystalline magnesium primary cooling coolant outlet 623, crystalline magnesium secondary cooling water inlet 624, crystalline magnesium secondary cooling water outlet 625, bearing support 711, driven gear 712, driving gear 713, driving bearing support 714, driving shaft 715, driving motor 716, sealed motor room 717. DETAILED DESCRIPTION

[0023] The exemplary embodiments will be described in detail herein with reference to the attached drawings. The description herein refers to the accompanying drawings, which show by way of illustration various embodiments of the application. The description herein makes reference to the accompanying drawings in which like reference numbers refer to like elements, and the inclusion of

[0024] It should be noted that the order of the steps of the respective methods is not necessarily the order in which the steps are executed in other embodiments. In some other embodiments, the methods comprise more or less steps than described in the present description. Further, a single step described in the present description can be split up into several sub-steps in other embodiments, and several sub-steps described in the present description can be combined into a single step in other embodiments.

[0025] Embodiment one The present scheme provides a system for indirect carbon thermal reduction of magnesium based on asynchronous double liquid phase catalysis, which solves the problem that Mg vapor obtained by high-temperature reduction reaction in the prior art reverts to reaction with CO gas in the furnace gas during the cooling process. The present scheme uses a certain active metal or alloy MX as an alloy reducing agent, and carbonaceous reducing agent is added in the initial stage to reduce the oxide slag phase of the alloy reducing agent to produce molten metal MX metal reducing agent, and the reaction system discharges CO gas; in the next stage, MgO is added to react with the MX metal reducing agent to generate Mg vapor, which is discharged outside the furnace for condensation to obtain metallic magnesium, and the by-product MX oxide remains in the furnace as a slag phase, waiting for the next stage of reducing agent regeneration stage, and carbonaceous reducing agent is added to reduce the molten state of MX oxide to regenerate the reducing agent. The two stages are alternately performed, and the CO and magnesium vapor discharged from the reaction system are also alternately performed and do not meet, so that the reverse reaction of carbon thermal reduction does not occur. Moreover, the metallic magnesium of the present scheme can be collected by liquid condensation, instead of being directly and rapidly condensed to obtain magnesium powder which is flammable and explosive and difficult to recover.

[0026] Specifically, Figure 1 is a schematic diagram of the overall structure of the system for indirect carbon thermal reduction of magnesium based on asynchronous double liquid phase catalysis provided by the present scheme. The system for indirect carbon thermal reduction of magnesium based on asynchronous double liquid phase catalysis of the present scheme comprises: The magnesium smelting arc furnace 101, wherein the magnesium smelting arc furnace 101 is provided with a double liquid phase molten pool mixed by a molten metal liquid and a molten slag, the molten slag contains at least one metal oxide, the molten metal liquid contains a base metal liquid and a live metal in a molten state, and the metal oxide and the live metal are of the same metal type, the magnesium smelting arc furnace 101 is used for alternately inputting a carbonaceous reducing agent and magnesium oxide to switch between a reducing agent regeneration stage and a magnesium smelting stage; The heat supplement chamber 120 connected with the furnace gas outlet 107 of the magnesium smelting arc furnace 101, used for maintaining or increasing the temperature of the furnace gas flowing out of the magnesium smelting arc furnace 101; The quench condenser 201 connected with the high-temperature furnace gas passage 123 of the heat supplement chamber 120, used for condensing the furnace gas generated in the reducing agent regeneration stage, and isentropically expanding and cooling the furnace gas generated in the magnesium smelting stage; The first cooling chamber 301 connected with the quench condenser 201, used for condensing the furnace gas generated in the reducing agent regeneration stage, and condensing the furnace gas generated in the magnesium smelting stage to obtain silicon oxide powder and crystalline magnesium powder; The second cooling chamber 310 connected with the gas passage of the first cooling chamber 301, used for condensing the furnace gas generated in the reducing agent regeneration stage, and further condensing the furnace gas generated in the magnesium smelting stage to obtain magnesium particles.

[0027] Regarding the magnesium smelting arc furnace 101 of the present scheme: The present scheme alternately inputs a carbonaceous reducing agent and magnesium oxide into the magnesium smelting arc furnace 101 to switch between a reducing agent regeneration stage and a magnesium smelting stage, wherein when the carbonaceous reducing agent is input into the magnesium smelting arc furnace 101, it is defined as the reducing agent regeneration stage, at this time the furnace gas of the reducing agent regeneration stage is CO, and when the magnesium oxide is input into the magnesium smelting arc furnace 101, it is defined as the magnesium smelting stage, at this time the furnace gas of the magnesium smelting stage is magnesium vapor and other gases.

[0028] In the reducing agent regeneration stage, the input carbonaceous reducing agent reduces the metal oxide in the molten slag to obtain the live metal dissolved in the molten metal liquid; and in the magnesium smelting stage, the input magnesium oxide reacts with the live metal in the molten metal liquid, at this time the live metal acts as a metal reducing agent to reduce the magnesium oxide to obtain gaseous magnesium vapor, and at the same time the live metal is oxidized to a metal oxide into the molten slag. Due to the alternately inputting of the carbonaceous reducing agent and the magnesium oxide in the present scheme, the reducing agent regeneration stage and the magnesium smelting stage are alternately performed all the time, and the entire process only consumes two materials, the magnesium oxide and the carbonaceous reducing agent, and the live metal exists in the molten slag or the molten metal liquid in the form of metal oxide and metal solute, but its state and quantity do not change significantly before and after the reaction, so it is only a medium of reduction ability, and does not participate in the macroscopic process of production.

[0029] That is, the input of magnesium oxide and carbonaceous reducing agent as raw materials throughout the process production line, and then the output of CO gas and magnesium metal vapor condensed magnesium, and because of the use of active metal and metal oxide as a medium, so that the output of CO gas and metal magnesium vapor output is asynchronous, avoiding the direct contact of the reverse reaction problem. In addition, the reaction process is involved in the liquid phase, and there is gas output, the overall molten pool is in a state of boiling, the flow state required for reaction mass transfer is far superior to the solid-solid contact reaction of direct carbon thermal reduction.

[0030] In some embodiments, the molten metal liquid contains a base metal liquid, wherein the base metal liquid is an alloy liquid with one or more of iron, copper, manganese, cobalt, nickel, chromium as the base. It should be noted that the metals in the base metal liquid are inert metals in the reducing agent regeneration stage and the magnesium smelting stage, only serving as a solvent for the molten metal liquid, and do not participate in chemical reactions In some embodiments, the base metal liquid contains one or a combination of Fe, Si, Mn, Cu, Ni, Cr, and Co.

[0031] In some embodiments, the metal species of the active metal contains one or a combination of Si, Al, Ca, Ba, B, La, Ce, Y, Gd, Eu, and Sm; and the metal oxide contains one or a combination of SiO2, Al2O3, TiO x , CaO, B2O3, La2O3, Ce2O3, Eu2O3, Y2O3, Gd2O3, and Sm2O3.

[0032] In some embodiments, when the base metal liquid is an iron-based metal liquid, at the beginning of the magnesium smelting stage, the mass concentration of silicon is 15-45wt.%, and the mass concentration of other metals is 1-5wt.%. This is because in the case of a relatively high silicon concentration, the iron-based alloy liquid can dissolve more alkaline earth metals Ca, Ba, and rare earth metal elements; and after the end of the magnesium smelting stage, the mass concentration of all other metal reducing agents except silicon generally decreases to 0.1-0.5wt.%, at which point the next reducing agent regeneration operation is required.

[0033] In some embodiments, the basicity of the molten slag is maintained in the range of 0.8-1.5. Acidic oxides are silicon, aluminum, and boron oxides, and the others are basic oxides. In particular, it is worth mentioning that the acid-base property of titanium oxide becomes more and more basic as the valence of titanium decreases. Titanium dioxide is amphoteric, more basic. In the strong reducing atmosphere of the magnesium smelting stage and the reducing agent regeneration stage, titanium exists in the form of divalent oxide and trivalent oxide in the molten slag, showing strong basicity, and rare earth oxides also RE2O3 are also basic in the strong reducing slag.

[0034] It is particularly emphasized that Si as a metalloid can be both a base metal of the base metal liquid and one of the active metals in the molten metal liquid.

[0035] As Figure 2 shown, Figure 2 is a process schematic of the reducing agent regeneration stage and the magnesium smelting stage in the magnesium smelting electric arc furnace 101. It can be seen that in the reducing agent regeneration stage, carbonaceous reducing agent is added to reduce the oxides of Si, Al, Ti, Ca, Ba, B, Y, La, Ce, Gd, Sm, Eu in the molten slag to obtain corresponding metal elements dissolved in the iron-based molten alloy liquid, and such active metals are denoted as MX, and the chemical equation can be approximately expressed as: .

[0036] In the magnesium smelting stage, magnesium oxide is added to the molten metal liquid, so that the active metals MX of Si, Al, Ti, Ca, Ba, B, Y, La, Ce, Gd, Sm, Eu in the molten metal liquid are reduced to obtain gaseous magnesium metal vapor, and the corresponding metal reducing agent oxides MXO x enter the molten slag, and the chemical equation can be approximately expressed as: .

[0037] The state of the catalyst in the dual-liquid-phase molten bath is shown in Table 1 below; Table 1 State of catalyst in dual-liquid-phase molten bath .

[0038] As can be seen from Table 1, the oxides, carbides and silicides of the metal reducing agent are all possible chemical reactions that may be involved in the above reducing agent regeneration link, among which the carbides and silicides are intermediate products that are ultimately reduced to active metal elements dissolved in the alloy liquid, and ultimately the metal elements and their low-valence oxides are recycled. The initial raw material for industrial production may be high-valence oxides such as TiO2 and CeO2, and after entering formal production, titanium may be in the form of TiO and Ti2O3, and cerium may be in the form of Ce2O3 and its metallic state alternately.

[0039] It should be noted that: a plurality of active metals are dissolved in the base metal liquid to form a high-temperature liquid molten pool to obtain molten metal liquid. Corresponding metal oxides, although having high melting points, have low eutectic points in the high-entropy state of the multi-metal oxide mixture, and are in a molten liquid state, i.e., molten slag. The multi-component mixed molten slag and the molten metal liquid maintain a low-viscosity, low-melting-point double-layer molten liquid phase. The double-liquid-phase molten pool is a liquid-liquid reaction, which has the advantages of good mass transfer conditions and superior reaction kinetics conditions compared to the conventional carbon reduction of metal oxides and the gas-solid reaction of magnesium smelting. The reaction speed is fast, and it is suitable for large-scale industrial production.

[0040] Moreover, the effect is better than that of using a single carbonaceous reducing agent or a single metal reducing agent, whether in the reducing agent regeneration stage or in the magnesium smelting stage. Chemical reaction thermodynamics is not simply a plurality of reactions parallel to each other without interaction, but produces a synergistic effect. For example, the carbonaceous reducing agent reduces silicon oxide while also reducing aluminum oxide, calcium oxide, barium oxide, titanium oxide, and rare earth oxides. Taking silicon and aluminum as examples, silicon oxide is relatively easy to reduce, and aluminum oxide is difficult to reduce. The silicon or silicon carbide that is reduced first can act as a reducing agent to a certain extent when reducing aluminum oxide, as shown in the following series of equations. Similarly, silicon has a similar effect on the synergistic reduction of titanium oxide, alkaline earth metals, and rare earth metals.

[0041] .

[0043] As shown in Figure 3 , the magnesium smelting electric arc furnace 101 is an electric arc heating furnace that is isolated from air and can be vacuumized. Specifically, the magnesium smelting electric arc furnace 101 of the present scheme includes an electric furnace steel shell 102, the electric furnace steel shell 102 is provided with a slag removal groove 108 inclined downward on one side, a furnace gas outlet 107 inclined upward on the other side, and an electrode inside.

[0044] It should be noted that the magnesium smelting electric arc furnace 101 can adopt an alternating current three-electrode, a direct current top and bottom double-electrode, or a direct current even-numbered top electrode. In the embodiment of the present scheme, the magnesium smelting electric arc furnace 101 adopts a top and bottom double-electrode, the top of the magnesium smelting electric arc furnace 101 is provided with a top electrode 105, and the bottom is provided with a bottom electrode 106. The top electrode is a cathode, and the bottom electrode is an anode.

[0045] In some embodiments, the top electrode 105 and the bottom electrode 106 both adopt super-high-power graphite electrodes, and the top electrode is a hollow electrode.

[0046] In some embodiments, the inner wall of the electric furnace steel shell 102 is provided with a graphite furnace lining 104 and a heat insulation layer 103, wherein the heat insulation layer 103 is disposed along the inner wall of the inner wall of the electric furnace steel shell 102, and the graphite furnace lining 104 is disposed on the surface of the heat insulation layer 103 and wraps the top electrode 105 and the bottom electrode 106.

[0047] In some embodiments, the apparatus for the co-production of silicon-carbon anode material by electric furnace thermal reduction of magnesium further includes: Magnesium oxide powder container 109, used to contain magnesium oxide; And toner canister 110, used to contain carbonaceous reducing agent.

[0048] In some embodiments, magnesium oxide from magnesium oxide powder container 109 or carbonaceous reducing agent from carbon powder container 110 is added from hollow top electrode 105, wherein the magnesium oxide is magnesium oxide particles or powder, and the carbonaceous reducing agent is coke particles or powder, bio-pyrolysis carbon particles or powder.

[0049] Furthermore, the magnesium oxide powder tank 109 and the carbon powder tank 110 can be transported in the gas phase using a carrier gas. The carrier gas type can be argon, hydrogen, or methane. If methane is used, the methane gas undergoes thermal decomposition under the high temperature of the electric arc at the end of the hollow electrode 105, producing hydrogen and carbon particles.

[0050] In other embodiments, such as Figure 4 As shown, the apparatus for the co-production of silicon-carbon anode material by thermal reduction of magnesium in an electric furnace further includes: a carbon powder immersion side-blowing nozzle 116 connected to the carbon powder tank 110 for conveying carbonaceous reducing agent into the molten metal; and a magnesium oxide powder immersion side-blowing nozzle 115 connected to the magnesium oxide powder tank 109 for conveying magnesium oxide into the molten metal. In this case, the carbon powder immersion side-blowing nozzle 116 and / or the magnesium oxide powder tank 109 use argon, hydrogen, or CH4 methane gas as carrier gases to blow the corresponding raw materials into the molten metal.

[0051] Regarding magnesium oxide, compared to the traditional carbothermic magnesium smelting process, the magnesium oxide in this scheme can contain SiO2. That is, the magnesium oxide can come from serpentine minerals, magnesium silicate minerals from asbestos tailings, or calcined magnesite powder with high silicon content. Similarly, the carbonaceous reducing agent can also be silicon oxide minerals carried by coke, semi-coke, and anthracite with high ash content.

[0052] Correspondingly, the SiO2 component undergoes the following reaction during the reducing agent regeneration stage in the magnesium smelting electric arc furnace 101 of this scheme:

[0053] Especially under high temperature and vacuum condition, the reduction of silicon oxide is more significant, and similar reduction reactions of aluminum, titanium, boron and other elements also occur. After silicon is reduced to a certain extent, the reduction of calcium oxide, barium oxide and rare earth oxides is easier to proceed when the molten metal has a certain concentration of silicon, that is, the synergistic effect mentioned above is achieved.

[0054] In some embodiments, the furnace gas produced in the reducing agent regeneration stage is mainly high-temperature CO gas, and there are also a small amount of silicon-aluminum low-valence gaseous oxides of SiO and Al2O, and almost no magnesium metal vapor. If methane or hydrogen is used as the carrier gas, there may be a small amount of hydrogen in the furnace gas. If oxygen is used as the carrier gas, there is a small amount of argon in the furnace gas.

[0055] The Si will refine magnesium stage occurs in the magnesium refining arc furnace 101 of the present scheme as follows: ; That is, in some embodiments, the furnace gas produced in the magnesium refining stage is mainly magnesium vapor, and there is also a small amount of SiO low-valence silicon oxide, and the temperature of the furnace gas produced in the magnesium refining stage is as high as 1700-2000°C. If hydrogen or argon is used as the carrier gas, there will also be a small amount of non-condensable hydrogen or argon in the furnace gas.

[0056] Regarding the carbonaceous reducing agent, in addition to the coke from the coke tank 110, the carbon in the magnesium refining arc furnace 101 can also come from bio-pyrolysis carbon and carbon black particles produced by thermal cracking of methane, corresponding to Bio-pyrolysis carbon is derived from the following:

[0057] Methane gas is thermally cracked under the action of high-temperature arc, and the reaction is as follows: .

[0058] Again, it needs to be emphasized that in the traditional direct carbon thermal reduction process, the temperature needs to exceed 2000°C under normal pressure under the action of high-temperature arc to cause the carbon thermal reduction magnesium refining reaction. Under a moderate vacuum negative pressure condition, this temperature can be reduced by 200 degrees Celsius or even more. However, at the same time, the reverse reaction of CO and Mg vapor occurs during the process of leaving the high-temperature zone, and carbon particles and magnesium oxide powder are re-generated, causing the yield of magnesium metal to be seriously low. However, since the CO gas and magnesium vapor of the present scheme are output in stages, the problems existing in direct carbon thermal reduction can be avoided.

[0059] Regarding the heat supplementing chamber 120 of the present scheme: In some embodiments, the heat supplementing chamber 120 contains a small-power electrode for arc heating to maintain or increase the temperature of the furnace gas. For example, Figure 5As shown, the heat supplement chamber 120 is provided with a heat supplement electrode anode 121 and a heat supplement electrode cathode 122.

[0060] Further, the heat supplement chamber 120 is connected with the quench condenser 201 through a high-temperature furnace gas passage 123 perpendicular to the heat supplement chamber 120.

[0061] In some embodiments, the heat supplement chamber 120 is connected with the furnace gas outlet 107 of the magnesium smelting arc furnace 101 through an adiabatic gas passage.

[0062] Regarding the quench condenser 201: As shown in Figure 6 and Figure 7 The quench condenser 201 includes a converging pipe 208, a throat 209, a diverging pipe 210 and a parallel pipe 211 connected in sequence, the opening diameter of the converging pipe 208 gradually decreases towards the throat 209, and the opening diameter of the diverging pipe 210 gradually increases towards the parallel pipe 211.

[0063] In some embodiments, the throat 209 and the parallel pipe 211 are pipes with uniform opening diameters, and the converging pipe 208 and the diverging pipe 210 are trumpet-shaped pipes.

[0064] In some embodiments, the maximum opening diameter of the diverging pipe 210 is smaller than the maximum opening diameter of the converging pipe 208.

[0065] In some embodiments, the quench condenser 201 is arranged perpendicular to the high-temperature furnace gas passage 123.

[0066] It should be noted that the furnace gas generated in the reducing agent regeneration stage and the magnesium smelting stage is different, the furnace gas generated in the reducing agent regeneration stage is CO gas, and there may also be a small amount of hydrogen and argon, while the furnace gas generated in the magnesium smelting stage is high-temperature magnesium vapor, and there may also be a small amount of hydrogen, argon, SiO unstable gas existing in the high-temperature section. The pressure ratio before and after the furnace gas generated in the reducing agent regeneration stage and the magnesium smelting stage passes through the quench condenser 201 is different, and if there is a large pressure difference between the heat supplement chamber 120 and the first cooling chamber 301 of the high-temperature furnace gas, a pressure ratio conforming to the realization of supersonic expansion is formed. At this time, the quench condenser 201 has the effect of supersonic isentropic expansion, which is embodied as a supersonic quench condenser, so this means that the quench condenser 201 has different effects on the furnace gas in different stages. The quench condenser 201 condenses the furnace gas generated in the reducing agent regeneration stage, and performs isentropic expansion and cooling treatment on the furnace gas generated in the magnesium smelting stage.

[0067] Specifically, the system for asynchronous indirect carbon thermal reduction of magnesium based on two-liquid-phase catalysis of the present solution additionally comprises a vacuum pump 321 connected to the second cooling chamber 310. In some embodiments, the vacuum pump 321 generally adopts a liquid ring pump, such as a water ring pump or an oil ring vacuum pump with oil as the medium. Such a pump has a low vacuum degree but a large air extraction capacity, which meets the vacuum degree requirement of magnesium refining.

[0068] When in the reducing agent regeneration stage, the vacuum pump 321 performs air extraction on the quench condenser 201 at an absolute pressure of 5-20 Kpa. At this time, the working condition volume flow of the CO gas before the vacuum pump 321 is only 5-20 times that at normal pressure, and the working condition volume flow value is very small, which cannot meet the minimum flow design value required by the supersonic speed nozzle, so the CO gas only flows in a subsonic speed manner.

[0069] When in the magnesium refining stage, the vacuum pump 321 performs air extraction on the quench condenser 201 at an absolute pressure of 0.3 Kpa. At this time, the working condition volume of the high-temperature side of the furnace gas expands, that is, the total volume of the gas input into the quench condenser 201 has met the gas flow range designed for the quench condenser 201, and the pressure ratio before and after the quench condenser 201 can reach 5-20 times or more. At this time, according to the design parameters of the supersonic speed Laval nozzle, the furnace gas is injected to flow through in a supersonic speed manner.

[0070] In some embodiments, the furnace gas generated in the magnesium refining stage is subjected to isentropic expansion in the quench condenser 201, so that the internal energy of the gas is converted into kinetic energy, achieving a 1.5-2.5 times supersonic speed jet, that is, Ma=1.5-2.5, and the overall temperature of the furnace gas is reduced at a rate of 10^6 K / s, that is, the overall temperature is significantly reduced in tens of milliseconds through the several-meter-long quench condenser 201, and in the stage of 1000°C or above, the SiO gas is first condensed to change phase and is frozen into solid SiO particles in the supersonic speed condensing section.

[0071] The following condensation changes of SiO in the quench condenser 201 are described. (1) Quench freezing of SiO gas: ; (2) Disproportionation reaction of SiO: ; (3) Reverse reaction of SiO generation reaction: ; (4) Magnesiothermic reduction reaction of SiO: .

[0072] Further, in order to quench the condensation effect of the condenser 201, the parallel pipe 211 uses indirect cooling means such as water cooling, air cooling, oil cooling, etc. to cool the furnace gas by external medium to consolidate the quenching cooling effect of the condenser 201.

[0073] In other words, when in the magnesium refining stage, the magnesium vapor in the furnace gas before the vacuum pump 321 has been mostly condensed into condensed state of liquid or solid, the magnesium vapor in the gas phase is minimal, and the SiO2 gas phase molecules are condensed or disproportioned into solid phase particles earlier than the magnesium vapor, and only a small amount of carrier gas argon or hydrogen exists in the gas phase. At this time, the vacuum pumping function of the vacuum pump 321 can be significantly exerted, and in the case of using silicon oil or vacuum pump oil as a liquid ring medium, the vacuum degree can reach the order of 0.3 KPa.

[0074] Regarding the first cooling chamber 301 of the present scheme: The first cooling chamber 301 of the present scheme is used to condense the furnace gas generated in the reducing agent regeneration stage, and to condense the furnace gas generated in the magnesium refining stage to obtain silicon oxide powder and crystalline magnesium powder.

[0075] Further, as shown in Figure 6 , the parallel pipe 211 enters from one side of the first cooling chamber 301 along the tangent of the inner wall of the first cooling chamber 301, so that the furnace gas in the magnesium refining stage forms a rotating gas in the first cooling chamber 301, which rotates downward under the action of centrifugal force and thus is better cooled, wherein the furnace gas in the magnesium refining stage includes cooled magnesium vapor and solid phase particles containing a small amount of Si.

[0076] As shown in Figure 7 , the top of the first cooling chamber 301 is provided with a plurality of first cooling upper evaporation heat exchangers 304, the outer wall of the first cooling chamber 301 is provided with a first cooling outer shell evaporation pipe 303, and the bottom is provided with a first cooling on-off valve 302. Further, the first cooling upper evaporation heat exchanger 304 is located above the connection position of the parallel pipe 211 and the first cooling chamber 301, and the first cooling outer shell evaporation pipe 303 wraps the lower part of the connection position of the parallel pipe 211 and the first cooling chamber 301. The furnace gas in the magnesium refining stage closely adheres to the inner wall of the first cooling chamber 301 and is directly cooled by the first cooling outer shell evaporation pipe 303, part of the gas rises and is cooled by the first cooling upper evaporation heat exchanger 304 at the upper part of the first cooling chamber 301, and then recondenses and drops or powders fall down, gathering at the bottom of the first cooling chamber 301 to form a magnesium-silicon binary mixed powder 309, which is then finally cooled to a complete cooling in the inner wall of the first cooling chamber 301. This is a continuous slow cooling stage, and the condensation of magnesium vapor mainly occurs in this stage, and the following reactions occur at this time: (5) Condensation reaction of magnesium vapor: .

[0077] In some embodiments, magnesium-silicon binary mixed powder 309 is collected at the bottom of the primary cooling chamber 301. The primary cooling chamber 301 is periodically opened to collect the magnesium-silicon binary mixed powder 309. The magnesium-silicon binary mixed powder 309 is fed into an argon-protected solid powder briquetting machine 501 to be compacted into blocks, and then fed into a magnesium distillation furnace 601 for vacuum distillation to distill metallic magnesium. The magnesium-silicon binary mixed powder 309 includes silicon oxide powder and partially crystalline magnesium powder.

[0078] Silicon oxides are relatively complex, with three products of silicon: silicon suboxide, elemental silicon (also known as industrial silicon, sometimes called metallic silicon, semi-metallic silicon, or semiconductor silicon), and silicon dioxide, all in certain proportions. Magnesium-silicon binary mixed powder 309 is discharged through a window periodically opened by a cold-operated valve 302 using a screw conveyor or similar method. It is then extruded and shaped by an argon-protected solid powder briquetting machine 501 and sent to a magnesium steam furnace 601 for vacuum distillation to distill metallic magnesium, while simultaneously achieving partial magnesium thermal reduction of silicon oxide (SiOx) and partial differentiation of silicon suboxide.

[0079] Regarding the second cooling chamber 310: The furnace gas output from the first cooling chamber 301 continues to enter the second cooling chamber 310 for cooling. The second cooling chamber 310 condenses the furnace gas generated during the reducing agent regeneration stage and further condenses the furnace gas generated during the magnesium smelting stage to obtain magnesium particles.

[0080] like Figure 7 As shown, the second cooling chamber 310 includes an upper secondary cooling water-cooling pipe 305. The second cooling chamber 310 is placed in a secondary cooling constant temperature water bath 306, and the secondary cooling constant temperature water bath 306 is provided with a secondary cooling water inlet 307 and a secondary cooling water outlet 308. A secondary cooling on / off valve is provided at the bottom of the second cooling chamber 310. The magnesium vapor in the magnesium smelting stage is cooled by the upper secondary cooling water-cooling pipe 305, and the magnesium particles gather on the side wall and bottom of the second cooling chamber 310.

[0081] The second cooling chamber 310 is also connected in sequence to a dust collector 320, a vacuum pump 321, and a by-product gas storage tank 322. The dust collector 320 is used to remove dust from the CO gas during the regeneration stage of the reducing agent and pressurizes it through the vacuum pump 321 before storing it in the by-product gas storage tank 322. CO and some H2 gas enter the by-product gas storage tank 322 after passing through the dust collector and exhaust fan. Existing technologies can be used to make it as fuel gas, or it can be used alone or together with hydrogen as raw material gas for chemical synthesis for comprehensive utilization.

[0082] like Figure 8As shown, the magnesium distillation furnace 601 of the present solution is used for distillation of the solid block extruded by the solid powder briquetting machine 501, and is sequentially connected with a distillation primary cooling chamber 603 and a distillation secondary cooling chamber 604, for cooling the furnace gas generated by distillation, wherein the furnace gas generated by distillation is condensed in the distillation primary cooling chamber 603 to obtain primary crystalline magnesium 608, and the furnace gas generated by distillation is further cooled in the distillation secondary cooling chamber 604 to obtain secondary crystalline magnesium 609.

[0083] In some embodiments, the temperature of the distillation primary cooling chamber 603 is maintained at 500-1000°C, and the magnesium volatilized is condensed to obtain pure crystalline magnesium.

[0084] In some embodiments, the magnesium distillation furnace 601 is externally provided with a heating chamber 602, and the heating chamber 602 is provided with a heat source inlet 620 and a waste heat source outlet 621, for heating the magnesium distillation furnace 601.

[0085] In some embodiments, the distillation primary cooling chamber 603 is externally provided with a primary cooling constant-temperature cooling tank 606, and the primary cooling constant-temperature cooling tank 606 is provided with a primary crystalline magnesium cooling agent inlet 622 and a primary crystalline magnesium cooling agent outlet 623.

[0086] In some embodiments, the distillation secondary cooling chamber 604 is externally provided with a secondary cooling constant-temperature liquid tank 607, and the secondary cooling constant-temperature liquid tank 607 is provided with a secondary crystalline magnesium cooling water inlet 624 and a secondary crystalline magnesium cooling water outlet 625, and the distillation secondary cooling chamber 604 is vacuumized by a vacuum pump 605.

[0087] In the magnesium distillation furnace 601, in addition to the vacuum volatilization of metallic magnesium, a magnesium thermal reduction reaction also occurs, and the reaction equation is as follows:

[0088]

[0089] The disproportionation reaction of SiO also occurs moderately:

[0090] The silicon-magnesium mixed material 507 is a raw material that can be used as a silicon negative electrode material, and is subjected to subsequent deep processing for use in high-capacity lithium batteries and the like.

[0091] In some embodiments, the primary crystalline magnesium 608 and the secondary crystalline magnesium 609 are solid crystalline magnesium, which, together with a small amount of residual crystalline magnesium at the bottom of the 310, is input into the argon-protected solid powder briquetting machine 510 for remelting ingot casting, and is sold as commercial magnesium or subjected to alloying and deep processing in the next step.

[0092] Embodiment Two The system of Example One is an indirect cooling method for cooling magnesium vapor. In addition to the method of Example One, the present application provides a magnesium rain splashing condensation method, Figure 9 is a schematic diagram of the overall structure of the system of the present application. In addition to the system of Example One, the system of the present application additionally includes: The magnesium liquid condenser 401 and the magnesium liquid surface adjusting chamber 402 are connected to the first cooling chamber 301. The magnesium liquid condenser 401 is connected to the first cooling chamber 301, and contains a main magnesium liquid pool 410. The magnesium liquid surface adjusting chamber 402 contains a secondary magnesium liquid pool 411. The main magnesium liquid pool 410 and the secondary magnesium liquid pool 411 are connected through a bottom communication pipe 403. The main magnesium liquid pool 410 and the secondary magnesium liquid pool 411 contain molten magnesium liquid or molten aluminum-magnesium large proportion alloy liquid. When the magnesium smelting electric arc furnace 101 is in the magnesium smelting stage, the liquid level of the main magnesium liquid pool 410 and the secondary magnesium liquid pool 411 is adjusted so that the liquid level of the main magnesium liquid pool 410 is higher than the bottom communication pipe 403, and the molten magnesium liquid or molten aluminum-magnesium large proportion alloy liquid in the main magnesium liquid pool 410 is splashed to condense the furnace gas generated in the magnesium smelting stage. When the magnesium smelting electric arc furnace 101 is in the reducing agent regeneration stage, the liquid level of the main magnesium liquid pool 410 and the secondary magnesium liquid pool 411 is adjusted so that the liquid level of the main magnesium liquid pool 410 is lower than the bottom communication pipe 403, for condensing the furnace gas generated in the reducing agent regeneration stage. The second cooling chamber 310 is connected to the magnesium liquid condenser 401 through a low-temperature furnace gas exhaust pipe 421, for condensing the furnace gas generated in the reducing agent regeneration stage, and further condensing the furnace gas generated in the magnesium smelting stage to obtain magnesium particles.

[0093] The other devices and structures of the system are the same as those of Example One, except that the system additionally introduces a magnesium liquid condenser between the quenching condenser 201 and the first cooling chamber 301 of Example One, to condense and recover the magnesium liquid.

[0094] The magnesium rain condenser 401 is described in detail below.

[0095] In some embodiments, the temperature of the molten magnesium liquid is about 30-100°C higher than the melting point of magnesium, i.e. 650°C, i.e. 680-780°C, and the mass ratio of aluminum to magnesium in the molten aluminum-magnesium large proportion alloy is about (35-65):(35-65), i.e. the mass ratio of the two alloying elements, aluminum and magnesium, is in the range of 35-65%, and the melting point of the aluminum-magnesium large proportion alloy in this range is lower than the melting point of each of the two elements by 170-180°C, i.e. the lowest melting point is about 480°C, and the temperature is kept about 30-100°C higher than the melting point, i.e. 510-610°C.

[0096] In some embodiments, the magnesium rain condenser 401 is connected to the first container 801 through the medium-temperature furnace gas exhaust pipe 420.

[0097] In some embodiments, the main magnesium liquid pool 410 is located at the bottom of the magnesium liquid condenser 401, and the auxiliary magnesium liquid pool 411 is located at the bottom of the magnesium liquid surface adjusting chamber 402, and the main magnesium liquid pool 410 and the auxiliary magnesium liquid pool 411 are connected through the bottom communication pipe 403, wherein the bottom communication pipe 403 is a heat preservation pipe and is a U-shaped pipe, so as to form a U-shaped communicating vessel with the molten magnesium liquid or the molten aluminum-magnesium large proportion alloy as the liquid medium.

[0098] In some embodiments, the magnesium liquid discharge valve 405 is arranged on the bottom communication pipe 403, so as to discharge the molten magnesium liquid or the molten aluminum-magnesium large proportion alloy in the main magnesium liquid pool 410 and the auxiliary magnesium liquid pool 411 when the molten magnesium liquid or the molten aluminum-magnesium large proportion alloy reaches the upper limit of the set value, so as to perform distillation operation. It should be noted that the distillation of the molten magnesium liquid or the molten aluminum-magnesium large proportion alloy is used to obtain the metal magnesium.

[0099] In some embodiments, the magnesium liquid discharge valve 405 is made of graphite or ceramic material, so as to have certain heat preservation measures.

[0100] In some embodiments, the magnesium liquid surface adjusting chamber 402 is provided with a gas pressure adjusting mechanism having a gas pressurizing function and a pressure reducing function, so as to adjust the liquid level of the molten magnesium liquid or the molten aluminum-magnesium large proportion alloy in the auxiliary magnesium liquid pool 411.

[0101] Specifically, the top of the magnesium liquid level regulating chamber 402 is equipped with an exhaust pipe 455 and an argon filling pipe 452. The exhaust pipe 455 is equipped with an exhaust valve 454 and a liquid level regulating vacuum pump 453, while the argon filling pipe 452 is equipped with an argon filling valve 451. When it is necessary to pressurize the magnesium liquid level regulating chamber 402, the argon pressure tank 450 is connected through the argon filling pipe 452, the argon filling valve 451 on the argon filling pipe 452 is opened, and the liquid level regulating vacuum pump 453 on the exhaust pipe 455 is closed. High-pressure argon gas from argon pressure tank 450 enters the magnesium liquid auxiliary pool 411 inside magnesium liquid level regulating chamber 402, causing the liquid level in magnesium liquid auxiliary pool 411 to drop. Consequently, the amount of alloy liquid in magnesium liquid auxiliary pool 411 decreases while the amount of alloy liquid in magnesium liquid main pool 410 increases. When it is necessary to depressurize magnesium liquid level regulating chamber 402, the liquid level regulating vacuum pump 453 of exhaust pipe 455 is opened, the argon filling valve 451 on argon filling pipe 452 is closed, and the magnesium liquid level regulating vacuum pump 453 is used to evacuate magnesium liquid level regulating chamber 402. The liquid level regulating vacuum pump 453 is connected to the upper cavity, i.e., the free space, of magnesium liquid level regulating chamber 402 through exhaust pipe 455. There is an on / off valve 454 on 455. Correspondingly, the gas pressure above magnesium liquid auxiliary pool 411 decreases, causing the liquid level in magnesium liquid auxiliary pool 411 to rise, and the liquid level in magnesium liquid main pool 410 to drop.

[0102] In some embodiments, a flywheel assembly 460 consisting of multiple flywheels is placed on the surface of the main magnesium liquid pool 410 of the magnesium liquid condenser 401 to agitate the main magnesium liquid pool 410 to create a centrifugal splashing effect, forming a "magnesium rain curtain" in the magnesium liquid condenser 401. After reaching the top, it falls down in a waterfall shape, colliding with and absorbing the magnesium vapor in the magnesium smelting stage, causing it to condense into droplets and capture and absorb them.

[0103] In some embodiments, the liquid-throwing flywheel assembly 460 is made of graphite, ductile iron, carbon steel, alloy steel, or stainless steel, with a ceramic protective coating on the surface. It has an outer diameter of 300-500 mm, a rotation speed of 300-600 rpm, and its central axis is flush with the molten magnesium liquid or molten aluminum-magnesium alloy liquid when stationary. It generally has multiple impellers on the same axis and is arranged in a multi-axis configuration.

[0104] Furthermore, such as Figure 12 and 13 As shown, the liquid-throwing flywheel assembly 460 is driven to rotate by the drive gear 713 and the driven gear 712. The driven gear 712 and the liquid-throwing flywheel assembly 460 are supported and fixed by the bearing bracket 711, and the driven gear 712 and the liquid-throwing flywheel assembly 460 are arranged on the same rotating shaft.

[0105] In some embodiments, the drive gear 713 is driven by a drive motor 716 outside the container, which transmits torque to the drive gear 713 through the drive shaft 715, and the common drive shaft 715 of the drive motor 716 and the drive gear 713 is arranged on the drive bearing frame 714.

[0106] In some embodiments, the drive motor 716 is located outside the wall of the first container 801 and is enclosed in a sealed motor room 717 to prevent the drive shaft sleeve of the drive shaft 715 from leaking air from the outside to the inside of the first container 801 at high temperature.

[0107] When the magnesium smelting arc furnace 101 is in the magnesium smelting stage, the liquid levels of the main magnesium liquid pool 410 and the auxiliary magnesium liquid pool 411 are regulated so that the liquid level of the main magnesium liquid pool 410 is higher than the bottom communication pipe 403, and the molten magnesium liquid or the molten aluminum-magnesium large proportion alloy liquid in the main magnesium liquid pool 410 is splashed to form magnesium rain, which enters the second cooling chamber 310.

[0108] In some embodiments, after the magnesium rain condensation lasts for a period of time, the magnesium content and the total liquid volume of the molten magnesium liquid or the molten aluminum-magnesium large proportion alloy liquid in the main magnesium liquid pool 410 continue to increase, and when the magnesium content reaches 60-70%, the melting point of the aluminum-magnesium liquid may increase. At this time, the argon gas pressure tank 450 is opened to release a part of the molten magnesium liquid or the molten aluminum-magnesium large proportion alloy liquid, and distillation is performed to obtain high-purity magnesium as a magnesium product. After remelting the ingot, it is sold or subjected to further processing. In some embodiments, the proportion of aluminum in the residual liquid of the molten aluminum-magnesium large proportion alloy liquid also rises to 60-70%, and this aluminum-magnesium alloy residual liquid is loaded into a sealed ladle for re-returning to the magnesium liquid level regulating chamber 402.

[0109] It should be noted that the condensation of magnesium vapor from high-temperature gas to medium-temperature liquid releases a large amount of latent heat of phase change and certain sensible heat of cooling, so a vacuum evaporation condenser 430 is needed to remove the corresponding heat from the magnesium rain condenser 401, i.e., the magnesium liquid condenser 401 is provided with the vacuum evaporation condenser 430.

[0110] In some embodiments, a water inlet main pipe 431 is vertically arranged in the vacuum evaporation condenser 430, and a plurality of water mist nozzles 432 are arranged on the water inlet main pipe 431. The top of the vacuum evaporation condenser 430 is connected to a negative pressure steam delivery pipe 434 through a negative pressure pump 433.

[0111] In some embodiments, when the temperature of the magnesium rain condenser 401 rises to a set temperature, the vacuum evaporation condenser 430 is turned on for cooling treatment. Specifically, water is turned on through the water inlet main pipe 431, water mist is sprayed from the multiple water mist nozzles 432, and the water mist is heated by the inner wall in the vacuum evaporation condenser 430 to evaporate due to heat absorption. The inner cavity of the vacuum evaporation condenser 430 is connected to the negative pressure pump 433 to form a negative pressure vacuum system. The water mist sprayed from the water mist nozzles 432 is evaporated and boiled into low-pressure water vapor at 70-90°C, which is discharged from the negative pressure pump 433. The residual gas is discharged from the negative pressure steam discharge pipe 434. The vacuum evaporation condenser 430 is cooled by the negative pressure evaporation-discharged steam or condensation, which forces the shell of the vacuum evaporation condenser 430 to cool down. When the temperature reaches the lower limit of the set temperature, the water inlet main pipe 431 stops supplying water, and the water mist no longer evaporates, so the temperature of the vacuum evaporation condenser 430 no longer continues to drop.

[0112] In some embodiments, the negative pressure pump 433 is preferably a water ring pump.

[0113] When the magnesium smelting electric arc furnace 101 is in the reducing agent regeneration stage, at this time, since the furnace gas in the reducing agent regeneration stage only has CO gas, in order to prevent the CO gas from causing oxidation to the magnesium liquid or the molten aluminum-magnesium alloy liquid, the liquid level of the main magnesium liquid pool 410 and the auxiliary magnesium liquid pool 411 is adjusted so that the liquid level of the main magnesium liquid pool 410 is lower than the bottom communication pipe 403, that is, the liquid level of the main magnesium liquid pool 410 is controlled to be within the bottom communication pipe 403.

[0114] As described in the content of Embodiment One, the vacuum pump 321 connected to the second cooling chamber 310 performs air extraction treatment at an absolute pressure of 5-20 Kpa when in the reducing agent regeneration stage. Since the vacuum pump 321 connected to the second cooling chamber 310 is preferably a water ring pump or a liquid ring pump with liquid oil as the medium, it has greater operating flexibility. Since the CO gas extracted by the vacuum pump 321 is non-condensable and the vacuum degree is not high, the vacuum degree of the magnesium rain condenser 401 can be adjusted to about 5-20 KPa through the vacuum degree-air extraction rate characteristics of the vacuum pump 321 and artificial frequency adjustment. By reducing the air pressure in the magnesium liquid adjusting chamber 402, the liquid level of the main magnesium liquid pool 410 can be lowered to below the bottom plate plane of the magnesium rain condenser 401.

[0115] As described above, in the reducing agent regeneration stage, the load of the vacuum evaporation condenser 430 becomes smaller, and only CO gas needs to be cooled. Without the condensation phase change latent heat of the metallic magnesium, the load of the vacuum evaporation condenser 430 is significantly reduced, and the CO can be cooled to a lower temperature.

[0116] In some embodiments, the bottom of the second cooling chamber 310 is connected to the argon-protected solid powder briquetting machine 501, i.e. the magnesium vapor at the bottom of the second cooling chamber 310 is extruded into a solid powder by the argon-protected solid powder briquetting machine 501 and is sent to the magnesium evaporation furnace 601 for vacuum distillation to distill the metallic magnesium.

[0117] Those skilled in the art should understand that the technical features of the above embodiments can be combined in any manner. In order to make the description simple, all possible combinations of the technical features in the above embodiments are not described, however, as long as the combinations of the technical features do not exist contradictions, they should be considered as the scope of the present disclosure.

[0118] The above embodiments only express several implementation manners of the present application, and the description is relatively specific and detailed, but it should not be understood as a limitation on the scope of the present application. It should be pointed out that for those skilled in the art, several modifications and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the appended claims.

Claims

1. A system for asynchronous indirect carbothermic reduction of magnesium based on two-liquid-phase catalysis, characterized in that, include: A magnesium smelting electric arc furnace (101) is provided with a two-phase molten pool containing a mixture of molten metal and molten slag. The molten slag contains at least one metal oxide, and the molten metal contains a base metal and a molten active metal. The metal oxide and the active metal are of the same type. The magnesium smelting electric arc furnace (101) is used to alternately introduce carbonaceous reducing agent and magnesium oxide to switch between the reducing agent regeneration stage and the magnesium smelting stage. A supplementary heating chamber (120) connected to the furnace gas outlet (107) of the magnesium smelting electric arc furnace (101) is used to maintain or increase the temperature of the furnace gas flowing out of the magnesium smelting electric arc furnace (101). A high-temperature furnace gas passage (120) connected to the supplementary heating chamber (120) is also provided. 23) A quenching condenser (201) is connected to condense the furnace gas generated in the reducing agent regeneration stage and to perform isentropic expansion and cooling treatment on the furnace gas generated in the magnesium smelting stage; a first cooling chamber (301) connected to the quenching condenser (201) is used to condense the furnace gas generated in the reducing agent regeneration stage and to perform condensation treatment on the furnace gas generated in the magnesium smelting stage to obtain silicon oxide powder and crystalline magnesium powder; and a second cooling chamber (310) connected to the gas passage of the first cooling chamber (301) is used to condense the furnace gas generated in the reducing agent regeneration stage and to perform further condensation treatment on the furnace gas generated in the magnesium smelting stage to obtain magnesium particles.

2. The system for asynchronous indirect carbothermic reduction of magnesium smelting via dual liquid-phase catalysis according to claim 1, characterized in that, The system includes a magnesium liquid condenser (401) and a magnesium liquid level regulating chamber (402) located between the first cooling chamber (301) and the second cooling chamber (310). The magnesium liquid condenser (401) is connected to the first cooling chamber (301). The magnesium liquid condenser (401) contains a main magnesium liquid pool (410), and the magnesium liquid level regulating chamber (402) contains a secondary magnesium liquid pool (411). The main magnesium liquid pool (410) and the secondary magnesium liquid pool (411) are connected by a bottom connecting pipe (403). The main magnesium liquid pool (410) and the secondary magnesium liquid pool (411) contain molten magnesium or molten aluminum-magnesium alloy liquid in a large proportion. When the magnesium smelting electric arc furnace (101) is in the magnesium smelting stage, the liquid levels of the main magnesium liquid pool (410) and the secondary magnesium liquid pool (411) are adjusted to ensure that the magnesium liquid... The liquid level in the main liquid tank (410) is higher than that in the bottom connecting pipe (403), and the molten magnesium liquid or molten aluminum-magnesium alloy liquid in the main liquid tank (410) is splashed to condense the furnace gas generated in the magnesium stage; when the magnesium smelting electric arc furnace (101) is in the reducing agent regeneration stage, the liquid levels of the main liquid tank (410) and the auxiliary liquid tank (411) are adjusted so that the liquid level in the main liquid tank (410) is lower than that in the bottom connecting pipe (403) for condensing the furnace gas generated in the reducing agent regeneration stage; and the second cooling chamber (310) connected to the magnesium liquid condenser (401) through the low temperature furnace gas exhaust pipe (421) is used to condense the furnace gas generated in the reducing agent regeneration stage, and to further condense the furnace gas generated in the magnesium smelting stage to obtain magnesium particles.

3. The system for asynchronous indirect carbothermic reduction magnesium smelting based on dual-liquid-phase catalysis according to any one of claims 1 or 2, characterized in that, The matrix metal liquid contains one or a combination of Fe, Si, Mn, Cu, Ni, Cr, and Co; the active metal species contains one or a combination of Si, Al, Ca, Ba, B, La, Ce, Y, Gd, Eu, and Sm; the metal oxide contains one or a combination of SiO2, Al2O3, TiOx, CaO, B2O3, La2O3, Ce2O3, Eu2O3, Y2O3, Gd2O3, and Sm2O3.

4. The system for asynchronous indirect carbothermic reduction magnesium smelting based on dual-liquid-phase catalysis according to any one of claims 1 or 2, characterized in that, include: Magnesium oxide comes from serpentine minerals, magnesium silicate minerals from asbestos tailings, or calcined magnesite powder with high silicon content. The carbonaceous reducing agent is the silicon oxide mineral carried by coke, semi-coke, and anthracite with high ash content.

5. The system for asynchronous indirect carbothermic reduction of magnesium based on dual-liquid-phase catalysis according to claim 1, characterized in that, The system includes a vacuum pump (321) connected to the second cooling chamber (310). During the reducing agent regeneration stage, the vacuum pump (321) pumps gas from the quenching condenser (201) at an absolute pressure of 5~20 kPa, and CO gas flows in the quenching condenser (201) at a subsonic speed. During the magnesium smelting stage, the vacuum pump (321) pumps gas from the quenching condenser (201) at an absolute pressure of 0.3 kPa, and the furnace gas generated during the magnesium smelting stage undergoes isentropic expansion in the quenching condenser (201).

6. The system for asynchronous indirect carbothermic reduction of magnesium based on dual-liquid-phase catalysis according to claim 1, characterized in that, Magnesium-silicon binary mixed powder (309) accumulates at the bottom of the primary cooling chamber (301). The primary cooling chamber (301) is periodically opened with a cooling valve (302) to collect the magnesium-silicon binary mixed powder (309). The magnesium-silicon binary mixed powder (309) is fed into an argon-protected solid powder briquetting machine (501) to be compacted into blocks. Then it is fed into a magnesium distillation furnace (601) for vacuum distillation to distill metallic magnesium. The magnesium-silicon binary mixed powder (309) includes silicon oxide powder and partially crystalline magnesium powder.

7. The system for asynchronous indirect carbothermic reduction of magnesium based on dual-liquid-phase catalysis according to claim 2, characterized in that, The temperature of the molten magnesium is 680-780℃, the mass ratio of aluminum to magnesium in the molten aluminum-magnesium alloy liquid is approximately (35~65):(35~65), and the temperature of the molten aluminum-magnesium alloy liquid is 510-610℃.

8. The system for asynchronous indirect carbothermic reduction of magnesium based on dual-liquid-phase catalysis according to claim 2, characterized in that, The magnesium liquid level regulating chamber (402) is equipped with a gas pressure regulating mechanism with gas pressurization and depressurization functions to regulate the liquid level of molten magnesium metal liquid or molten aluminum-magnesium alloy liquid in the magnesium liquid auxiliary liquid tank (411). A magnesium liquid discharge valve (405) is installed on the bottom connecting pipe (403) to discharge molten magnesium metal liquid or molten aluminum-magnesium alloy liquid when the molten magnesium metal liquid or molten aluminum-magnesium alloy liquid in the magnesium liquid main liquid tank (410) and magnesium liquid auxiliary liquid tank (411) reaches the upper limit of the set value.

9. The system for asynchronous indirect carbothermic reduction of magnesium based on dual-liquid-phase catalysis according to claim 2, characterized in that, A set of flywheels (460) consisting of multiple flywheels is placed on the surface of the main liquid pool (410) of the magnesium liquid condenser (401) to agitate the main liquid pool (410) of the magnesium liquid to create a centrifugal splashing effect.

10. The system for asynchronous indirect carbothermic reduction magnesium smelting based on dual-liquid-phase catalysis according to claim 2, characterized in that, The magnesium liquid condenser (401) is equipped with a vacuum evaporation condenser (430). When the temperature of the magnesium liquid condenser (401) rises to the set temperature, the vacuum evaporation condenser (430) is turned on to perform cooling.

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