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Vacuum electrothermal magnesium smelting apparatus with protector

A protective device and vacuum technology, which is applied in the field of non-ferrous metal magnesium extraction and metallurgy, can solve problems such as harsh working environment, serious smoke pollution, and delay in production time, and achieve the effects of increasing smelting rate, strengthening specific surface area, and reducing potential safety hazards

Active Publication Date: 2015-05-27
牛强
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AI Technical Summary

Problems solved by technology

[0014] 1. The reactant ferrosilicon and calcined white react chemically in the form of solid phase contact, the reaction rate is slow, and the reduction reaction cycle in a typical process is as long as 10 to 12 hours, which is inefficient;
[0015] 2. The flame is used for external heating, and the heat is gradually transferred from the outside of the reactor to the inside. The cycle is long, the heat energy loss is large, and the heat energy utilization rate is low. According to professional analysis, the heat energy utilization rate of a typical process is only about 20%;
[0016] 3. Due to the limitation of the reactor volume by the external heating method, the inner diameter of a typical horizontal tank is within 400 mm, generally 300-370 mm in diameter, and the amount of material charged at one time is small. The output of raw magnesium in a single tank is only 20-12 hours. 30 kg, covers a large area and is difficult to manage on-site, making it difficult to achieve large-scale production and mechanized operations;
[0017] 4. Ferrosilicon containing 75% silicon is used as the reducing agent. Generally, the consumption per ton of magnesium ferrosilicon is 1.05 to 1.20 tons, that is, silicon far exceeds the theoretical consumption value and causes waste, and at the same time all iron elements are wasted;
[0018] 5. Horizontal tanks generally use expensive heat-resistant steel containing nickel and chromium, which consumes quickly and costs high;
[0019] 6. The smoke pollution is serious, the working environment is harsh, and the negative impact on the surrounding ecological environment is great;
[0020] 7. It requires manual loading, slag removal, and cleaning of crystalline magnesium, which is labor-intensive and difficult to achieve automated operations
but if figure 2 As shown, under vacuum conditions, high voltage causes thin gas to be easily broken down, and the stability of the arc deteriorates. Therefore, the voltage used for arc heating under vacuum is often only 20-30 volts, and the highest is no more than 60-70 volts, for example Common vacuum consumable electric furnaces have a serious shortage of heating power. As a comparison, high-power electric arc furnaces used in steelmaking under normal pressure have a voltage of 400-800 volts, and the voltage of ultra-high-power arc rate is as high as 1000-1500 volts. The electric heating power of the vacuum consumable electric arc furnace is much smaller than that of the ultra-high power steelmaking electric arc furnace
In some patents, plasma heating is used. Since the maximum power of a single plasma gun is only a few MW, more than a dozen or even dozens of heaters must be configured, resulting in extremely complicated equipment and high cost.
[0029] The Magnetherm method operates under vacuum, does not use arc heating, but uses electroslag heating that does not rely on air ionization, the electric heating power is small, the yield and production capacity are low, and the production capacity per furnace is less than one ton per hour, and it is semi-continuous , the amount of slag in silicothermal magnesium smelting is very large, and the amount of slag per ton of magnesium reaches 6-8 tons. The slag needs to break the vacuum, and repeated vacuuming will delay a lot of production time, causing a pause in continuous production, and the intermediate process will inevitably bring Thermal shock cycles of refractory materials, resulting in reduced refractory life
[0030] The temperature of MTMP process is too high, the loss of refractory material is large, and the content of primary magnesium impurities is high
In order to achieve full continuous production, the MTMP process adopts the process of normal pressure operation. On the one hand, it does not need to change the vacuum condition for slag discharge, so it can be fully continuous. More importantly, it can use a higher voltage stable arc operation under normal pressure. This requires raising the furnace temperature to above 1700 degrees, so that the reduction reaction of magnesium smelting can occur, but the excessively high furnace temperature brings about the increase of energy consumption and the reduction of the service life of the lining refractory material
Moreover, due to the high furnace temperature, substances that are less volatile than magnesium also enter the gas phase in large quantities, and the purity of magnesium vapor decreases obviously, as shown in Table 2

Method used

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  • Vacuum electrothermal magnesium smelting apparatus with protector
  • Vacuum electrothermal magnesium smelting apparatus with protector
  • Vacuum electrothermal magnesium smelting apparatus with protector

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0091] The vacuum electric furnace 101 is a vacuum direct current electric arc furnace, the furnace lining is made of carbonaceous refractory material, the upper part is a graphite hollow cathode 120, the graphite bottom anode 130 is located at the bottom of the furnace, and there is an arc stabilizing magnetic field generator 140 under the bottom anode 130. The coil of the arc stabilizing magnetic field generating device 140 generates a magnetic field after being energized, which can generate electromagnetic force on the DC arc generated between the hollow cathode 120 and the bottom anode 130, so that the arc tends to be stable after being stressed. The wall of the cathode cavity 121 inside the hollow cathode 120 is lined with a layer of thin steel plate, so as to protect the cathode cavity 121 inner wall of the graphite from being scoured by powdery charge, the top of the hollow cathode 120 is connected with a sealed mineral powder tank 106, and Connected to a hollow cathode ...

Embodiment 2

[0102] In this embodiment, 60% liquid ferrosilicon is used as the reducing agent, and the calcined dolomite is the raw material of magnesium ore, containing 23% magnesium, and the diameter is not more than 40mm. The maximum inner diameter of the middle part of the vacuum DC electric arc furnace is 6000mm, the inner diameter of the furnace bottom is 4200mm, and the inner height is 5100mm. The power of the DC power supply is 50MW, the maximum voltage is 800 volts, the current is 60-70KA, and the control temperature is 1600 degrees Celsius during normal operation. The graphite hollow cathode 120 has a diameter of 1300mm, the inner diameter of the cathode cavity 121 is 300mm, the pressure in the furnace is 10000Pa, the argon pressure in the hollow cathode 120 is 14000Pa, and calcined white powder with a diameter less than 6mm enters the hollow cathode 120 for feeding, accounting for 10% of the total magnesium ore. 16%, the diameter greater than 6mm is fed into the furnace through ...

Embodiment 3

[0106] The vacuum electric furnace 101 is a closed medium-frequency electromagnetic induction electric furnace with a frequency of 100 Hz and a rated power of 20,000 kW, which is heated by induction heating with a water-cooled copper coil. The internal charging volume is 60 tons of liquid steel material. Since the density of ferrosilicon is lower than that of steel, the mass of molten ferrosilicon loaded during the actual magnesium smelting operation is about 30-40 tons. The top of the vacuum induction furnace 101 is provided with a liquid injection port 103 , a feeding port 104 and a magnesium vapor outlet 105 . All the magnesium ores are lumps of more than 3 mm in size, and all of them are fed into the furnace from the storage tank 108 through the feeding port 104 . The ferrosilicon liquid is added into the furnace from the ferrosilicon liquid injection tank 109 installed above the liquid injection port 103 . The bottom of the furnace is equipped with a bottom blowing argon...

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Abstract

The invention relates to a vacuum electrothermal magnesium smelting apparatus with a protector, belonging to the technical field of nonferrous metal magnesium extraction metallurgy. The apparatus comprises an electric-heating vacuum electric furnace, wherein the lower part is provided with a liquid outlet, and the upper part is provided with a liquid injection port, a feed port and a magnesium vapor outlet; the magnesium vapor outlet is communicated to a magnesium vapor condensing chamber through a sealed thermal-insulation pipeline, and then connected to a vacuum pump; the liquid outlet of the vacuum electric furnace is positioned inside a vacuum deslagging chamber; and the vacuum electric furnace and vacuum deslagging chamber are arranged inside an argon protective chamber. The vacuum magnesium smelting reactor (especially hollow cathode direct-current arc furnace) by using electricity as the heat source has high electrothermal power, is suitable for large-scale production, and greatly enhances the productive capacity of metal magnesium. The peripheral argon protective barrier can prevent air from leaking into the magnesium smelting furnace, which can cause severe safety production accidents, thereby greatly enhancing the safety of the magnesium smelting production device. The vacuum electrothermal magnesium smelting apparatus implements continuous production, greatly enhances the single-furnace magnesium yield, and obtains the original metal magnesium with lower impurity content.

Description

technical field [0001] The invention belongs to the technical field of extraction and metallurgy of non-ferrous metal magnesium, in particular to equipment for electrothermal magnesium smelting. Background technique [0002] Magnesium and magnesium alloys are the lightest metal structural materials. They are used in transportation, electronic products, building materials, aerospace and other fields to bring energy-saving effects. They are known as "the third metal" and "the first metal of the 21st century Green Metallic Materials". Mineral resources of major metal materials such as steel and aluminum are gradually being exhausted, while metallic magnesium is very rich in mineral resources, and seawater contains even more abundant magnesium resources, which can be used by humans for thousands of years. [0003] The technology for extracting metal magnesium from natural minerals is divided into two categories: electrolysis and thermal reduction. Magnesium chloride is general...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22B26/22
CPCY02P10/20
Inventor 牛强
Owner 牛强
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