Vacuum system in ferroalloy smelting

Since the establishment and development of metallurgical industry, people have been exploring various technological methods, so as to reduce the influence of atmospheric environment and impurities on metal smelting, but it has not been able to fundamentally solve this problem, until the emergence of vacuum smelting technology, metallurgical technology has made a fundamental breakthrough. There are many methods of ferroalloy smelting, one of which is to use vacuum system to smelting. Therefore, the application of vacuum system in ferroalloy smelting is analyzed.

Main uses of ferroalloy:

1. Deoxidizer. In the process of steelmaking, oxygen in molten steel is removed, and some iron alloys can also remove other impurities such as sulfur and nitrogen.

2. Alloy additive. According to the requirements of steel composition, alloy elements are added to the steel to improve the performance of steel.

3. Inoculant. Before casting, the cast iron is added into the iron water to improve the crystal structure of the casting.

4. A reduction agent for the production of other ferrous and non-ferrous metals by metal thermal reduction; a non-ferrous alloy

5. Additives; also used in a small amount in chemical and other industries.

6. Steel, all steel is one of ferroalloys, which makes ferroalloys the most widely used and most used alloy.

According to the product variety and quality requirements, different smelting methods are adopted for ferroalloy, including carbon reduction (blast furnace, electric furnace), metal thermal reduction method and electrolysis method; and the refining methods such as desilication refining, oxygen blowing, vacuum solid state decarbonization and so on can be used for refining. Some alloy elements are very low in ore content, and must be enriched first, including mineral processing and hydrometallurgy or pyrometallurgy treatment, extraction of pure oxide or other intermediate products, and then smelting.

Vacuum system is widely used in various vacuum systems which need high pumping speed and low and high vacuum, and it is the first choice for coarse vacuum and medium vacuum system. For example: vacuum smelting, degassing of steel, vacuum sintering, dynamic vacuum acquisition in large space simulation experiment, vacuum impregnation treatment of power capacitor and transformer, exhaust gas from automatic production line of fluorescent tube and bulb, continuous exhaust of heat preservation bottle liner, pre pumping in vacuum coating equipment, suction in magnesium reduction process, degassing in single silicon refining process, etc.

Vacuum metallurgy is a metallurgical operation under the condition of lower than standard atmospheric pressure. It can realize the metallurgical process which cannot be carried out in the atmosphere, prevent metal oxidation, separate substances with different boiling points, remove the gas or impurities in the metal, enhance the deoxidation ability of carbon in the metal and improve the quality of metal and alloy. Vacuum metallurgy is generally used in smelting, refining, casting and heat treatment of metals. With the rapid development of advanced science and technology, special vacuum system for metallurgy is widely used in smelting rare metals, steel and special alloys.

Through the analysis of the application of vacuum system in ferroalloy smelting, it can be seen that the important role of vacuum in metallurgical process is as follows:

1. to create favorable chemical thermodynamics and dynamic conditions for metallurgical reaction of gaseous products, so that some metallurgical processes difficult to be carried out under atmospheric pressure can be realized in vacuum condition;

2. reduce the solubility of gas impurities and volatile impurities in metals, and correspondingly reduce their content in metal;

3. reduce the temperature required for the volatilization of metal or impurities, and improve the separation coefficient between metal and impurities;

4. reduce or avoid the effect of metal or other reactants on air and avoid the pollution of gas impurities on metal or alloy.