Method and device for smelting magnesium through continuous reduction by liquid aluminothermy

Abstract

The invention discloses a method and a device for continuously smelting and reducing magnesium from molten aluminum. The method comprises the following steps: 1) grinding magnesium oxide until the fineness does not exceed 300 meshes; (2) the aluminum material is melted into molten aluminum, the molten aluminum is conveyed into a vacuum tank through a molten aluminum tank, and the vacuum degree in the vacuum tank is smaller than or equal to 15 Pa or 1000-2000 Pa; the temperature of the molten aluminum is 1000-1250 DEG C; (3) magnesium oxide powder is sprayed into the aluminum liquid level in the vacuum tank through a spray gun, the powder spraying rate is 5-20 kg / s, magnesium oxide reacts with the aluminum liquid, during the reaction, the aluminum liquid or solid aluminum needs to be continuously supplemented into the aluminum liquid tank, and the aluminum adding rate is 1.8-7.4 kg / s; (4) the magnesium oxide reacts with the molten aluminum to generate Al2O3 and magnesium steam, the Al2O3 is discharged from the molten aluminum tank, and the magnesium steam enters a crystallizer to be cooled to 600 DEG C to be subjected to solid crystallization; or the magnesium steam is cooled into liquid magnesium, the liquid magnesium is collected by a magnesium liquid collector, and the cooling temperature of the magnesium steam is 660-700 DEG C; continuous magnesium discharging is achieved, and the problems that a solid-phase reaction heating means is low in efficiency, the service life of the tank body is short, the single-tank yield is low, and the utilization value of magnesium reducing slag is low are solved.

Description

Technical Field

[0001] The invention relates to a raw magnesium smelting technology, and in particular to a method and a device for smelting magnesium by continuous reduction using a liquid aluminothermic method. Background Art

[0002] At present, the Pidgeon process is the main technology used in magnesium smelting in my country.

[0003] The Pijiang process is to reduce and calcine dolomite (calcined white) with ferrosilicon (75% Si) under 1200℃ and high vacuum (<15pa) conditions by externally heating the reduction tank (reducing metal magnesium container). Because of its advantages of short process flow, simple equipment, flexible production scale, and high purity of finished magnesium, coupled with my country's rich magnesium ore dolomite resources and solid fuel coal resources, it has been promoted and applied in my country. Although the energy consumption and pollution of the Pijiang process have been reduced to a certain extent through continuous improvements, there are still some problems that are difficult to overcome:

[0004] 1. External heating is adopted, and the heat is gradually transferred from the outside of the reduction tank to the inside. The solid material balls placed in the tank are poor conductors of heat, and the thermal energy utilization rate is low.

[0005] 2. The existing Pijiang process is a solid phase reaction, which has the processes of adding materials, vacuuming, breaking vacuum and slag discharge, and cannot achieve continuous magnesium output, and has low efficiency.

[0006] 3. In the process of reducing magnesium metal, the reduction tank is made of high-cost heat-resistant steel containing nickel, chromium and other elements. Even so, in an environment of 1250℃ and 15Pa, the service life of the reduction tank is still short, with an average life of 3-4 months.

[0007] 4. Due to the limited capacity of the reduction tank, the current maximum size of a single container is about φ566mm, with a loading capacity of about 600kg. A single reduction tank can produce 90-100kg of raw magnesium in 18 hours, and a single tank can produce 120-133kg of magnesium per day, resulting in a small amount of raw material loading and a low output of metallic magnesium.

[0008] 5. The collected magnesium is solid crystal and cannot be collected in liquid form. The refining process of magnesium requires remelting, which consumes a lot of energy and cannot achieve continuous magnesium production.

[0009] 6. The magnesium reduction slag produced is solid waste, which has no good utilization method, low value, and even requires solid waste disposal fees.

[0010] There are also studies on the aluminothermic method. The aluminothermic method is to reduce and calcine magnesite with aluminum powder to produce magnesium at 1200°C and high vacuum (<15pa) conditions by externally heating the reduction tank (reducing metal magnesium container). However, since this method also faces the six problems of the Pidgeon method mentioned above, and the cost of aluminum is higher than that of ferrosilicon, this method has not been applied in industry.

[0011] Both the traditional Pidgeon process and the thermite process are solid-phase reactions, which means that the raw materials for smelting need to be ground into powders of fine enough particle size, mixed according to the process proportion requirements, and then prepared (pressed) into pellets of a certain strength and shape to increase the mutual contact between the materials and achieve the purpose of promoting the reaction.

[0012] Chinese patent CN113789450A discloses "a method for preparing metallic magnesium by aluminothermic production". Its raw materials are calcined white and aluminum-containing reducing agents. In principle, the reducing agent ferrosilicon in the Pidgeon process is simply replaced with aluminum. The process still requires pelletizing and solid-phase reaction. The magnesium content in dolomite is lower than that in magnesite, resulting in higher carbon emissions. The slag produced is calcium aluminate, which has low utilization value.

[0013] Chinese patent CN1664135 discloses a method for extracting magnesium using dolomite (MgCO3, CaCO3), brucite (Mg(OH)2) and magnesite (MgOCO3) as raw materials and aluminum metal as a reducing agent, wherein the weight of each raw material is calculated according to the reaction formula and the actual material is weighed: after mixing and briquetting, the raw materials are added to a reduction tank, and the reduction tank is added to a reduction furnace. The essence is still a solid phase reaction, and the problem of solid phase reaction cannot be avoided.

[0014] Chinese patent CN101906544A discloses a "double-immersion tube ferrosilicon bath vacuum circulation magnesium smelting device and method thereof" and Chinese patent CN1019099005A discloses a "vacuum circulation molten silicon thermal method for magnesium smelting and equipment thereof". The method comprises: allowing molten liquid ferrosilicon with a temperature of 1350-1600°C and a silicon content of 30-65% and magnesium ore powder containing magnesium oxide mixed therein to periodically pass through a container with a vacuum degree of 350Pa to 10000Pa in a circular flow manner; the magnesium oxide in the magnesium ore powder is reduced by the silicon in the above-mentioned molten liquid ferrosilicon to generate magnesium vapor; and the magnesium vapor is condensed into liquid magnesium and collected. The equipment includes a vacuum container, a heating container, a magnesium ore powder delivery device and a magnesium vapor collection device. An ascending immersion pipe and a descending immersion pipe extend from the bottom of the vacuum container respectively, and the lower pipe openings of the ascending immersion pipe and the descending immersion pipe are immersed in the molten liquid ferrosilicon contained in the heating container. The pipe wall of the ascending immersion pipe is also connected to an argon gas blowpipe. The circulation principle of the RH device for steelmaking and refining is used to reduce magnesium with silicon in ferrosilicon liquid. Its essence is a silicon thermal method, and the melting temperature of ferrosilicon is relatively high, 150 to 400°C higher than that of the Pidgeon method, resulting in high energy consumption. It is also necessary to continuously adjust the silicon content of the reduced ferrosilicon liquid. In addition, the slag produced is still the magnesium reduction slag of the Pidgeon method, and the utilization value is low.

[0015] In summary, the existing aluminothermic reduction magnesium smelting process cannot solve the inherent problems of solid phase reaction, and the cost is higher than that of silicon thermal method, and it has not been industrialized. The liquid silicon thermal method has high energy consumption and is difficult to control, so it cannot be industrialized. Summary of the invention

[0016] The object of the present invention is to provide a method and device for continuous reduction of magnesium smelting by liquid aluminothermic method, which realizes continuous magnesium output and solves the problems of low efficiency of solid phase reaction heating means, short tank life, low single tank output, low utilization value of magnesium reduction slag, etc. in the prior art.

[0017] To achieve the above object, the technical solution of the present invention is:

[0018] A method for continuously smelting and reducing magnesium by liquid aluminum comprises the following steps:

[0019] 1) Grinding magnesium oxide to a fineness not exceeding 300 mesh; preferably, the fineness of magnesium oxide is 50 to 300 mesh;

[0020] 2) Melt the aluminum material into aluminum liquid and transport it to the vacuum tank through the aluminum liquid tank. The vacuum degree in the vacuum tank is ≤15Pa, and the temperature of the aluminum liquid is controlled at 1000~1250℃;

[0021] 3) Spray magnesium oxide powder into the aluminum liquid surface in the vacuum tank through a spray gun, and control the powder spraying rate at 5-20 kg / s; magnesium oxide reacts with aluminum liquid, and during this period, it is necessary to continuously add aluminum liquid or solid aluminum to the aluminum liquid tank, and the aluminum addition rate is 1.8-7.4 kg / s;

[0022] 4) Magnesium oxide reacts with aluminum liquid to generate aluminum oxide and magnesium vapor. The aluminum oxide is discharged from the aluminum liquid tank, and the magnesium vapor is cooled to 600°C in the crystallizer and solidified in the crystallizer.

[0023] The present invention also provides a method for continuously smelting and reducing magnesium by liquid aluminum, which comprises the following steps:

[0024] 1) Grinding magnesium oxide to a fineness not exceeding 300 mesh; preferably, the fineness of magnesium oxide is 50 to 300 mesh;

[0025] 2) Melt the aluminum material into aluminum liquid and transport it to the vacuum tank through the aluminum liquid tank. The vacuum degree in the vacuum tank is 1000-2000Pa, and the temperature of the aluminum liquid is controlled at 1000-1100℃;

[0026] 3) Spray magnesium oxide powder into the aluminum liquid surface in the vacuum tank through a spray gun, and control the powder spraying rate at 5-20 kg / s; magnesium oxide reacts with aluminum liquid, and during this period, it is necessary to continuously add aluminum liquid or solid aluminum to the aluminum liquid tank, and the aluminum addition rate is 1.8-7.4 kg / s;

[0027] 4) Magnesium oxide reacts with aluminum liquid to generate aluminum oxide and magnesium vapor. The aluminum oxide is discharged from the aluminum liquid tank, and the magnesium vapor is cooled to become liquid magnesium, which is then collected by the magnesium liquid collector. The cooling temperature of the magnesium vapor is 660-700°C.

[0028] Furthermore, the aluminum liquid enters the vacuum tank from the aluminum liquid tank through the riser, and the liquid level in the aluminum liquid tank drops. At this time, the rising height of the aluminum liquid tank is controlled to ensure that the length of the lower part of the riser inserted below the aluminum liquid level is 500-600mm; at the same time, a driving gas is blown into the lower part of the riser, combined with the downcomer connecting the vacuum tank and the aluminum liquid tank, so that the aluminum liquid forms a circulation between the vacuum tank and the aluminum liquid tank; wherein, the driving gas flow rate is controlled at 20-40Nl / min, and the driving gas is preferably argon.

[0029] Preferably, the aluminum oxide produced after the reduction reaction is completed floats to the slag layer on the surface of the aluminum liquid in the aluminum liquid tank as the aluminum liquid circulates continuously, and the slag produced is removed through the slag removal port designed on the aluminum liquid tank.

[0030] Preferably, the magnesium oxide powder is sprayed through a powder tank using a carrier argon gas in a spray gun inserted into the vacuum tank.

[0031] Preferably, the magnesium oxide is ground to a powder with a fineness of 50 to 300 mesh.

[0032] In the method of the present invention:

[0033] Preparation of magnesium-containing materials: calcining magnesite to obtain magnesium oxide, or calcining magnesium hydroxide to obtain magnesium oxide. Dolomite can also be calcined to obtain calcined white, and the calcined white is used to separate calcium and magnesium to extract magnesium oxide. However, it is not recommended to use calcined white directly for reduction, because calcined white contains calcium, and direct reduction will reduce calcium. In addition, the slag produced is calcium aluminate, which has low utilization value. The present invention uses magnesium oxide as the magnesium-containing material. The magnesium oxide is ground to a fineness of 50 to 300 mesh, and the overall fineness of the powder does not exceed 300 mesh. If the powder is too fine, it will be sucked away when entering the vacuum tank, resulting in low utilization rate; when the powder is too coarse, when the solid phase particles react with the liquid phase aluminum, it is not conducive to the liquid aluminum reducing agent to enter the core of the magnesium oxide for chemical reaction, and it is easy to produce an unreacted "core" due to incomplete reaction.

[0034] The vacuum tank is used as a reaction vessel and is made of boiler steel. High-aluminum refractory materials are built inside. High-aluminum refractory materials will not react with aluminum liquid and have good resistance to high-temperature erosion. The vacuum tank is designed with two immersion pipes, one for the riser and the other for the downcomer. Argon gas is blown into the lower part of the riser to drive the aluminum liquid to rise into the vacuum tank.

[0035] Aluminum is made of various pure aluminum materials such as pure aluminum ingots, pure aluminum particles, pure aluminum blocks, pure aluminum rods, pure aluminum wires, recycled scrap aluminum, etc., which are placed in an aluminum liquid tank and melted by electric induction heating.

[0036] The aluminum liquid enters the vacuum tank through the immersion pipe, and the vacuum tank is evacuated. The driving gas (argon) is blown into the lower part of the riser. The gas expands due to heat and the pressure decreases, causing isothermal expansion. The volume of the bubbles increases exponentially, thereby driving the aluminum liquid to rise and spray out into the vacuum tank like a fountain. As the bubbles burst, the aluminum liquid becomes tiny droplets, which greatly increases the surface area by dozens of times. Due to the difference in weight, the excess aluminum liquid in the tank returns to the aluminum liquid tank through the downcomer. The aluminum liquid in the aluminum liquid tank continuously enters the vacuum tank from the upcomer, thus forming a continuous circulation process of aluminum liquid. The circulation rate is a key parameter. If the circulation rate is slow, the efficiency of reducing magnesium is low. If the circulation rate is too fast, the magnesium oxide powder and magnesium vapor that cannot react will be brought into the aluminum liquid tank by the downcomer, and the magnesium oxide powder will enter the slag layer. The magnesium vapor will boil and overflow from the surface of the aluminum liquid in the aluminum liquid tank, causing an accident.

[0037] The magnesium oxide powder is sprayed into the powder tank by an argon-carrying spray gun inserted into the vacuum tank at a distance of about 200 mm above the driving side of the aluminum liquid surface in the vacuum tank. The feeding can be directly put into the vacuum tank by the vacuum silo, but the powder is directly put into the vacuum tank by gravity, and will be sucked away by the vacuum system in large quantities, resulting in low utilization rate; if the block material is used, it will react too slowly with the aluminum liquid, and the core of the material will not have time to react and enter the downcomer with the aluminum liquid. The feeding can also be carried out by spraying powder or putting in block materials into the aluminum liquid tank. In this way, part of the material will float to the surface of the aluminum liquid in the aluminum liquid tank and enter the slag layer, and will not enter the vacuum chamber through the immersion tube, resulting in low material utilization rate. The present invention adopts the method of spraying magnesium oxide powder on the surface of the aluminum liquid in the vacuum tank. The matching of the spraying rate of magnesium oxide powder and the circulation flow rate of aluminum liquid is the core process. If the powder spraying rate is too slow, the magnesium production rate is low. If the powder spraying rate is too fast, the powder will not have time to react and will enter the aluminum liquid tank with the downcomer and float into the slag.

[0038] In the magnesium reduction reaction, the aluminum liquid and the magnesium oxide powder rapidly undergo a reduction reaction, and the magnesium vapor precipitates from the aluminum liquid and is pumped away. The reaction product, aluminum oxide particles, flows through the downcomer along with the aluminum liquid and then floats to the slag layer.

[0039] Adding aluminum, according to the continuous reaction and consumption of aluminum liquid and magnesium oxide, it is necessary to continuously add aluminum to the aluminum liquid tank to maintain the aluminum liquid level. You can add molten aluminum liquid or solid aluminum. The rate of adding aluminum should be equivalent to the consumption.

[0040] There are two methods for collecting magnesium vapor: solid crystallization method and liquid method, depending on the form of magnesium at different temperatures and vacuum levels.

[0041] Slag removal, the product of the reduction reaction, aluminum oxide, floats to the slag layer on the surface of the aluminum liquid in the aluminum liquid tank as the aluminum liquid circulates continuously, and the slag layer becomes thicker and thicker. There is a slag removal port designed on the aluminum liquid tank to continuously remove the slag. The main component of the slag is aluminum oxide, which is recycled and separated into pure aluminum for reuse. Aluminum oxide can be used as electrolytic aluminum or refractory raw material.

[0042] The present invention uses the above method to continuously reduce liquid aluminum to smelt magnesium, which solves the problems of low efficiency of solid-phase reaction heating means and low single-tank output in the prior art, and realizes continuous collection and continuous output of magnesium vapor; the designed vacuum tank reaction container solves the problem of low tank life in the prior art, and the reaction product aluminum oxide of the method has higher utilization value than the magnesium reduction slag in the prior art.

[0043] The present invention also provides a device for continuously smelting and reducing magnesium with liquid aluminum, comprising:

[0044] Aluminum liquid tank, with a lifting device at the bottom;

[0045] A vacuum tank is arranged above the aluminum liquid tank at the treatment position, and an ascending pipe and a descending pipe are arranged at the bottom of the vacuum tank, and the lower ends of the ascending pipe and the descending pipe are inserted into the aluminum liquid tank; the vacuum tank is connected to the vacuum pump group through a vacuum pipe; an argon gas blowing pipe is arranged at the lower part of the ascending pipe; preferably, the vacuum tank is made of boiler steel, and a high-aluminum refractory material is built inside the vacuum tank;

[0046] A powder tank connected to the vacuum tank through a pipeline;

[0047] The crystallizer or magnesium liquid collector is connected to the top of the vacuum tank through a pipeline and a cooling device.

[0048] Preferably, the aluminum liquid tank is heated by electric induction heating.

[0049] Preferably, the vacuum pump group is a mechanical pump group or a steam jet pump group.

[0050] Preferably, the lower portion of the vacuum tank is a conical structure.

[0051] In the device design of the present invention:

[0052] The vacuum tank is used as a reaction vessel, and high-aluminum refractory materials are built inside. High-aluminum refractory materials will not react with aluminum liquid and have good resistance to high-temperature erosion. The purpose of designing the lower part of the vacuum tank as a conical structure is to facilitate the downward flow of aluminum liquid in the tank without dead corners.

[0053] There are two immersion pipes designed under the vacuum tank, one is an ascending pipe and the other is a descending pipe. Argon gas is blown into the lower part of the ascending pipe to drive the aluminum liquid to rise into the vacuum tank.

[0054] The aluminum liquid tank is preferably designed with two aluminum liquid tanks, a processing station in the middle, and two standby stations on both sides. The aluminum liquid tank after the aluminum is melted is moved to the bottom of the vacuum tank of the processing station and raised by hydraulic jacking.

[0055] The vacuum pump group draws the vacuum, and the vacuum pump group can be in the form of a mechanical pump group or a steam jet pump group. The steam jet pump group consumes steam. As the vacuum degree in the vacuum tank decreases, a pressure difference is formed between the inside and outside of the vacuum tank. The aluminum liquid will be sucked into the vacuum tank through two immersion pipes and rise to a height that is balanced with the pressure difference. As the aluminum liquid enters the vacuum tank, the liquid level in the aluminum liquid tank will drop. At this time, it is necessary to control the rising height of the aluminum liquid tank to ensure that the length of the immersion pipe inserted below the aluminum liquid surface is 500 to 600 mm.

[0056] The magnesium oxide powder is continuously sprayed into the aluminum liquid surface in the vacuum tank through a spray gun, and the magnesium oxide reacts continuously with the aluminum liquid. The magnesium vapor is continuously collected through the designed magnesium solid crystallizer or liquid collector to achieve continuous magnesium output. During this period, aluminum liquid or solid aluminum is continuously added to the aluminum liquid tank to ensure that there is enough aluminum liquid to continuously participate in the reaction.

[0057] Compared with the prior art, the advantages of the present invention are:

[0058] 1. The existing Pidgeon process and thermite process are both solid-phase reactions, and both involve the processes of adding materials, evacuating, breaking vacuum, and removing slag. They cannot achieve continuous operation and have low efficiency.

[0059] The present invention adopts a liquid aluminum reduction magnesium smelting method to achieve a continuous feeding and continuous magnesium output process, thereby greatly improving the operating efficiency.

[0060] 2. The capacity of the reduction tank in the existing technology is limited, resulting in a limited amount of raw materials to be loaded, and the output of magnesium metal in a single tank is not high, with the maximum daily output of a single tank being about 120-133 kg. To increase the output, the only way is to increase the number of tanks, resulting in a significant increase in investment and floor space.

[0061] The present invention is not limited by the volume of the vacuum tank, and a set of devices can continuously add aluminum, continuously add materials, and continuously produce magnesium. The vacuum tank continuous processing system with an inner diameter of φ1800mm is designed, and the daily magnesium output can reach about 200t, which greatly increases the output of metal magnesium in a single tank and greatly reduces the occupied area.

[0062] 3. The magnesium collected by the prior art is solid crystal and cannot be collected in liquid form. The refining process of magnesium requires remelting, which consumes a lot of energy and cannot achieve continuous magnesium production.

[0063] The present invention can directly collect liquid magnesium for subsequent refining without cooling, crystallizing and remelting processes, thereby reducing energy consumption.

[0064] 4. The prior art adopts an external heating method of placing a high alloy reduction tank in a heating furnace. The solid material balls placed in the tank are poor conductors of heat, with low thermal efficiency and long heating time.

[0065] The aluminum liquid tank of the present invention adopts an electric induction heating method, and the thermal efficiency is greatly improved compared with the external heating method of the heating furnace.

[0066] 5. In the prior art, during the reduction process of magnesium metal, the reduction tank is made of high-cost heat-resistant steel containing nickel, chromium and other elements. In an environment of 1250°C and 15Pa, the service life is short, about 3 to 4 months.

[0067] The vacuum tank, one of the core devices of the present invention, is composed of a boiler steel shell and refractory materials. Due to the protection of the refractory materials inside, the heating temperature of the steel shell is greatly reduced, and the service life of the steel shell can reach more than 5 years, which is greatly improved compared with the traditional reduction tank for magnesium smelting.

[0068] 6. The magnesium reduction slag produced by the existing technology is solid waste, which has no good utilization method, low value, and even requires solid waste disposal fees.

[0069] The magnesium reduction slag produced by the present invention mainly contains aluminum oxide, and the pure aluminum is recovered and separated for reuse. The aluminum oxide can be used as a raw material for electrolytic aluminum or refractory materials, and has a high value. BRIEF DESCRIPTION OF THE DRAWINGS

[0070] Figure 1 It is a stereogram of the system embodiment 1 for continuous smelting and reducing magnesium with liquid aluminum according to the present invention;

[0071] Figure 2 It is a stereogram of the system embodiment 2 for continuous smelting and reducing magnesium with liquid aluminum according to the present invention; DETAILED DESCRIPTION

[0072] The present invention will be further described below in conjunction with the embodiments and drawings.

[0073] See also Figure 1 , Figure 2 The device for continuous smelting and reducing magnesium of liquid aluminum of the present invention comprises:

[0074] Aluminum liquid tank 1, with a lifting device 2 at the bottom;

[0075] The vacuum tank 3 is arranged above the aluminum liquid tank 1, and an ascending pipe 4 and a descending pipe 5 are arranged at the bottom of the vacuum tank 3, and the lower ends of the ascending pipe 4 and the descending pipe 5 are inserted into the aluminum liquid tank 1; the vacuum tank 3 is connected to the vacuum pump group 6 through a vacuum pipeline; an argon gas blowing pipeline is arranged at the lower part of the ascending pipe 4;

[0076] A powder tank 7, connected to the vacuum tank 3 through a pipeline;

[0077] The crystallizer 8 or the magnesium liquid collector 9 is connected to the top of the vacuum tank 3 through a pipeline and a cooling device 10.

[0078] Preferably, the aluminum liquid tank 1 is heated by electric induction heating.

[0079] Preferably, two aluminum liquid tanks 1, 1' are designed, with a processing station in the middle and two standby stations on both sides.

[0080] Preferably, the vacuum pump group 6 is a mechanical pump group or a steam jet pump group.

[0081] Preferably, the lower portion of the vacuum tank 3 is a conical structure.

[0082] Example 1

[0083] See also Figure 1 The method for continuously smelting and reducing magnesium with liquid aluminum of the present invention comprises the following steps:

[0084] 1) Grind magnesium oxide to a fineness of 50 mesh;

[0085] 2) The aluminum liquid tank is powered on and induction heated to melt about 25 tons of aluminum for about 2 hours. The aluminum liquid temperature is controlled at about 1250°C. The aluminum liquid tank is lifted by hydraulic jacking until the riser is inserted 500mm below the aluminum liquid surface.

[0086] 3) The vacuum pump group evacuates the vacuum to 15Pa. As the aluminum liquid enters the vacuum tank, the liquid level in the aluminum liquid tank will drop. At this time, it is necessary to control the rising height of the aluminum liquid tank to ensure that the length of the immersion tube-rising tube inserted below the aluminum liquid level is about 500mm;

[0087] 4) Blow driving gas (argon) from the lower part of the riser, and control the flow rate to 20Nl / min to make the aluminum liquid continuously form a circulation between the vacuum tank and the aluminum liquid tank;

[0088] 5) The magnesium oxide powder is sprayed through the powder tank by an argon-carrying spray gun inserted into the vacuum tank, about 200 mm above the driving side of the aluminum liquid level in the vacuum tank, and the powder spraying rate is controlled at 5 kg / s; according to the continuous reaction and consumption of aluminum liquid and magnesium oxide, it is necessary to continuously add aluminum liquid or solid aluminum to the aluminum liquid tank to maintain the aluminum liquid level, and the aluminum adding rate is 1.8 kg / s;

[0089] 6) The reduced magnesium vapor is cooled to 600°C in the crystallizer and directly solidified in the crystallizer;

[0090] 7) After the reduction reaction is completed, the product of aluminum oxide floats to the slag layer on the surface of the aluminum liquid in the aluminum liquid tank as the aluminum liquid circulates continuously. The aluminum liquid tank is designed with a slag removal port to continuously remove the generated slag.

[0091] Example 2

[0092] See also Figure 1 The method for continuously smelting and reducing magnesium with liquid aluminum of the present invention comprises the following steps:

[0093] 1) Grind magnesium oxide to a fineness of 300 mesh;

[0094] 2) The aluminum liquid tank is powered on and induction heated to melt about 25 tons of aluminum for about 2 hours. The aluminum liquid temperature is controlled at about 1250°C. The aluminum liquid tank is lifted by hydraulic jacking until the immersion pipe-rising pipe is inserted about 500mm below the aluminum liquid surface.

[0095] 3) The vacuum pump group evacuates the vacuum to 15Pa. As the aluminum liquid enters the vacuum tank, the liquid level in the aluminum liquid tank will drop. At this time, it is necessary to control the rising height of the aluminum liquid tank to ensure that the length of the immersion tube inserted below the aluminum liquid surface is about 500mm;

[0096] 4) Blow driving gas (argon) from the lower part of the riser, and control the flow rate to 40Nl / min, so that the aluminum liquid continuously forms a circulation between the vacuum tank and the aluminum liquid tank;

[0097] 5) The magnesium oxide powder is sprayed through the powder tank by an argon-carrying spray gun inserted into the vacuum tank, about 200mm above the driving side of the aluminum liquid level in the vacuum tank, and the powder spraying rate is controlled at 20kg / s; according to the continuous reaction and consumption of aluminum liquid and magnesium oxide, it is necessary to continuously add aluminum liquid or solid aluminum to the aluminum liquid tank to maintain the aluminum liquid level, and the aluminum addition rate is 7.4kg / s;

[0098] 6) The reduced magnesium vapor is cooled to 600°C in the crystallizer and directly solidified in the crystallizer;

[0099] The product of the reduction reaction, aluminum oxide, floats to the slag layer on the surface of the aluminum liquid in the aluminum liquid tank as the aluminum liquid circulates continuously. The aluminum liquid tank is designed with a slag removal port to continuously remove the generated slag.

[0100] Example 3

[0101] See also Figure 2 , a method for continuously smelting and reducing magnesium with liquid aluminum, comprising the following steps:

[0102] Magnesium oxide is ground to a fineness of 50 mesh;

[0103] The aluminum liquid tank is powered on and induction heated to melt about 25 tons of aluminum in about 2 hours. The aluminum liquid temperature is controlled at about 1100℃.

[0104] The aluminum tank at the processing station is raised by hydraulic jacking until the immersion pipe-rising pipe is inserted about 500mm below the aluminum liquid surface;

[0105] The vacuum pump group evacuates to 1000Pa. As the aluminum liquid enters the vacuum tank, the liquid level in the aluminum liquid tank will drop. At this time, it is necessary to control the rising height of the aluminum liquid tank to ensure that the length of the immersion tube inserted below the aluminum liquid surface is about 500mm;

[0106] The driving gas (argon) is blown into the lower part of the riser, and the flow rate is controlled at 20Nl / min, so that the aluminum liquid continuously forms a circulation between the vacuum tank and the aluminum liquid tank;

[0107] The magnesium oxide powder is sprayed through the powder tank by an argon-carrying spray gun inserted into the vacuum tank, about 200mm above the driving side of the aluminum liquid level in the vacuum tank, and the powder spraying rate is controlled at 5kg / s; according to the continuous reaction and consumption of aluminum liquid and magnesium oxide, it is necessary to continuously add aluminum liquid or solid aluminum to the aluminum liquid tank to maintain the aluminum liquid level, and the aluminum adding rate is 1.8kg / s;

[0108] The product of the reduction reaction, aluminum oxide, floats to the slag layer on the surface of the aluminum liquid in the aluminum liquid tank as the aluminum liquid circulates continuously. The aluminum liquid tank is designed with a slag removal port to continuously remove the slag; the reduced magnesium vapor is cooled to 660°C, becomes liquid magnesium, and drips into the magnesium liquid collector.

[0109] Example 4

[0110] See also Figure 2 , a method for continuously smelting and reducing magnesium with liquid aluminum, comprising the following steps:

[0111] Grind magnesium oxide to a fineness of 300 mesh;

[0112] The aluminum liquid tank is powered on and induction heated to melt about 25 tons of aluminum in about 2 hours. The aluminum liquid temperature is controlled at about 1100℃.

[0113] The aluminum liquid tank is lifted by hydraulic jacking until the immersion pipe-rising pipe is inserted about 500mm below the aluminum liquid surface;

[0114] The vacuum pump group evacuates to 2000Pa. As the aluminum liquid enters the vacuum tank, the liquid level in the aluminum liquid tank will drop. At this time, it is necessary to control the rising height of the aluminum liquid tank to ensure that the length of the immersion tube inserted below the aluminum liquid surface is about 500mm;

[0115] Aluminum liquid circulation, the driving gas (argon) is blown into the lower part of the riser, and the flow rate is controlled at 40Nl / min, so that the aluminum liquid continuously forms a circulation between the vacuum tank and the aluminum liquid tank;

[0116] The magnesium oxide powder is sprayed through the powder tank by using an argon gas-carrying spray gun inserted into the vacuum tank, about 200mm above the driving side of the aluminum liquid level in the vacuum tank, and the powder spraying rate is controlled at 20kg / s;

[0117] According to the continuous reaction and consumption of aluminum liquid and magnesium oxide, it is necessary to continuously add aluminum liquid or solid aluminum to the aluminum liquid tank to maintain the aluminum liquid level. The aluminum addition rate is 7.4kg / s.

[0118] The product of the reduction reaction, aluminum oxide, floats to the slag layer on the surface of the aluminum liquid in the aluminum liquid tank as the aluminum liquid circulates continuously. The aluminum liquid tank is designed with a slag removal port to continuously remove the slag; the reduced magnesium vapor is cooled to 700°C, becomes liquid magnesium, and drips into the magnesium liquid collector.

Claims

1. A method for continuously smelting and reducing magnesium by liquid aluminum, characterized in that: The steps include: 1) Grinding magnesium oxide to a fineness not exceeding 300 mesh; preferably, the fineness of magnesium oxide is 50 to 300 mesh; 2) Melt the aluminum material into aluminum liquid and transport it to the vacuum tank through the aluminum liquid tank. The vacuum degree in the vacuum tank is ≤15Pa, and the temperature of the aluminum liquid is controlled at 1000~1250℃; 3) Spray magnesium oxide powder into the aluminum liquid surface in the vacuum tank through a spray gun, and control the powder spraying rate at 5-20 kg / s; magnesium oxide reacts with aluminum liquid, and during this period, it is necessary to continuously add aluminum liquid or solid aluminum to the aluminum liquid tank, and the aluminum addition rate is 1.8-7.4 kg / s; 4) Magnesium oxide reacts with aluminum liquid to generate aluminum oxide and magnesium vapor. The aluminum oxide is discharged from the aluminum liquid tank, and the magnesium vapor is cooled to 600°C in the crystallizer and solidified in the crystallizer.

2. A method for continuously smelting and reducing magnesium by liquid aluminum, characterized in that: The steps include: 1) Grinding magnesium oxide to a fineness not exceeding 300 mesh; preferably, the fineness of magnesium oxide is 50 to 300 mesh; 2) Melt the aluminum material into aluminum liquid and transport it to the vacuum tank through the aluminum liquid tank. The vacuum degree in the vacuum tank is 1000-2000Pa, and the temperature of the aluminum liquid is controlled at 1000-1100℃; 3) Spray magnesium oxide powder into the aluminum liquid surface in the vacuum tank through a spray gun, and control the powder spraying rate at 5-20 kg / s; magnesium oxide reacts with aluminum liquid, and during this period, it is necessary to continuously add aluminum liquid or solid aluminum to the aluminum liquid tank, and the aluminum addition rate is 1.8-7.4 kg / s; 4) Magnesium oxide reacts with aluminum liquid to generate aluminum oxide and magnesium vapor. The aluminum oxide is discharged from the aluminum liquid tank, and the magnesium vapor is cooled to become liquid magnesium, which is then collected by the magnesium liquid collector. The cooling temperature of the magnesium vapor is 660-700°C.

3. The method for continuous smelting and reducing magnesium by liquid aluminum as claimed in claim 1 or 2, characterized in that: The aluminum liquid enters the vacuum tank from the aluminum liquid tank through the riser. The vacuum degree of the vacuum tank is ≤15Pa, or 1000-2000Pa. The liquid level in the aluminum liquid tank drops. At this time, the rising height of the aluminum liquid tank is controlled to ensure that the length of the lower part of the riser inserted below the aluminum liquid level is 500-600mm; at the same time, the driving gas is blown into the lower part of the riser, combined with the downcomer connecting the vacuum tank and the aluminum liquid tank, so that the aluminum liquid forms a circulation between the vacuum tank and the aluminum liquid tank; wherein, the driving gas flow rate is controlled at 20-40Nl / min, and the driving gas is preferably argon.

4. The method for continuous smelting and reducing magnesium by liquid aluminum as claimed in claim 1 or 2, characterized in that: The product of the reduction reaction, aluminum oxide, floats to the slag layer on the surface of the aluminum liquid in the aluminum liquid tank as the aluminum liquid circulates continuously, and the slag produced is removed through the slag removal port designed on the aluminum liquid tank.

5. The method for continuous smelting and reducing magnesium from liquid aluminum as claimed in claim 1 or 2, characterized in that: The magnesium oxide powder is sprayed through the powder tank using the carrier argon gas in the spray gun inserted into the vacuum tank.

6. The method for continuous smelting and reducing magnesium by liquid aluminum as claimed in claim 1 or 2, characterized in that: Aluminum is made of pure aluminum ingots, pure aluminum particles, pure aluminum blocks, pure aluminum rods, pure aluminum wires or recycled scrap aluminum, which are placed in an aluminum liquid tank and melted by electric induction heating.

7. A device for continuous smelting and reducing magnesium from liquid aluminum, characterized in that: include: Aluminum liquid tank, with a lifting device at the bottom; A vacuum tank is arranged above the aluminum liquid tank processing station, and an ascending pipe and a descending pipe are arranged at the bottom of the vacuum tank, and the lower ends of the ascending pipe and the descending pipe are inserted into the aluminum liquid tank; the vacuum tank is connected to the vacuum pump group through a vacuum pipe; an argon gas blowing pipe is arranged at the lower part of the ascending pipe; preferably, the vacuum tank is made of boiler steel, and a high-aluminum refractory material is built therein; A powder tank connected to the vacuum tank through a pipeline; The crystallizer or magnesium liquid collector is connected to the top of the vacuum tank through a pipeline and a cooling device.

8. The device for continuous smelting and reducing magnesium by liquid aluminum as claimed in claim 7, characterized in that: The aluminum liquid tank is heated by electric induction heating.

9. The device for continuous smelting and reducing magnesium by liquid aluminum as claimed in claim 7, characterized in that: The vacuum pump group is a mechanical pump group or a steam jet pump group.

10. The device for continuous smelting and reducing magnesium by liquid aluminum as claimed in claim 7, characterized in that: The lower part of the vacuum tank is a conical structure.

Images