Vacuum electrothermal magnesium smelting apparatus with protector

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...

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

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