What is Ferro Silicon?
Ferrosilicon is an alloy composed of iron and silicon. Ferrosilicon is an alloy made of coke, steel shavings and silica as raw materials and smelted in an electric furnace.
Since silicon and oxygen are easily combined into silicon dioxide, ferrosilicon is often used as a deoxidizer in steelmaking. Because SiO2 releases a lot of heat when it is formed, it is also beneficial to increase the temperature of molten steel while deoxidizing. Ferrosilicon can also be used as an alloying element additive, and is widely used in low alloy structural steel, spring steel, bearing steel, heat-resistant steel and electrical silicon steel. Ferrosilicon is often used as a reducing agent in ferroalloy production and chemical industry.
With the development of iron and steel production technology, the iron and steel industry has increasingly stringent requirements on the content of impurities in ferroalloys, and the requirements for trace elements in ferrosilicon (such as Ti, P, C, Al, Ca, etc.) are becoming more and more stringent. The amount of trace elements determines the quality of ferrosilicon.
In the existing production of high-purity ferrosilicon (including low-carbon ferrosilicon), the carbides in ferrosilicon mainly exist in the form of SiC, and it is inevitable that some carbides enter the alloy during the smelting process, which will cause silicon There is too much carbon content in iron, which affects the quality of ferrosilicon and affects the price of ferrosilicon.
Therefore, it is very necessary to solve the defect of high carbon content in existing ferrosilicon.
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High-purity Ferrosilicon Production Process
In order to improve the quality of ferrosilicon and reduce the carbon content in ferrosilicon, we have improved the smelting method of ferrosilicon to produce high-purity ferrosilicon with lower carbon content.
Select quartz stone, reducing agent and silicon steel sheet as raw materials, add them into the ladle, heat and melt.
When the molten iron in the ladle accounts for one-third of its volume, weigh the slagging agent and add it to the ladle. The slagging agent accounts for 1%-3% of the ferrosilicon raw material.
Oxygen and compressed air are blown from the bottom of the ladle
Removal of slag on the surface of molten iron
Sampling is taken to check the molten iron content, and the processing is completed until the color is bright.
The Advantage of This Ferrosilicon Production Method
Most of C exists in the form of SiC in ferrosilicon melt, but some of it exists in the form of free carbon. Therefore, it is possible to promote a part of the carbon to react [C]+[O]=CO↑ by blowing oxygen into the melt; at the same time, it is also possible to destroy SiC by artificially adding a slag-forming agent, so that the reaction is towards the production of silicon. Direction movement, promote SiC precipitation and float, and then achieve the purpose of reducing the carbon content in the melt.
The requirements for raw materials are relatively strict. Concentrated materials must be used in the furnace. Quartz stone is made of first-grade materials. The reducing agent is stone tar with very low ash content. Silicon steel sheets are used instead of ordinary steel shavings to reduce impurity elements that cannot be treated by oxidation reactions The amount brought in.
The smelting operation adopts a carbon-deficient operation (the batch of tar into the furnace stone is about 2% lower than the theoretical calculation batch) to suppress the reduction of elements with a higher reduction temperature than silicon. of anthracite, gas char or wood.
Ventilation bricks are arranged at the bottom of the ladle, and copper pipes are arranged inside the ventilation bricks, and oxygen and compressed air are passed through the copper pipes.
When the iron is tapped to one-third of the molten iron content, slowly add the slagging agent, turn on the air compressor and oxygen tank, and evenly and slowly blow the mixed gas into the bottom of the furnace (the purpose of oxygen blowing is first to prevent the slagging agent from Agglomeration or pelletization, promoting slag melting, and compensating for insufficient temperature of molten iron. Secondly, through oxidation, impurities in molten iron form relatively stable oxides and enter the slag phase to achieve the purpose of impurity removal and purification.)
When bottom blowing, you should control the appropriate amount of air, which is suitable to make the molten iron tumbling. The blowing time also depends on the color of the ferrosilicon bonded to the sampling rod. The blowing can be stopped when the color is bright; Remove the slag before it forms a large amount of solid matter. At this time, the molten slag is water-like slag, which can be separated from the molten iron and can be dumped.
When bottom blowing, you should control the appropriate amount of air, which is suitable to make the molten iron tumbling. The blowing time also depends on the color of the ferrosilicon bonded to the sampling rod. The blowing can be stopped when the color is bright; Remove the slag before it forms a large amount of solid matter. At this time, the molten slag is water-like slag, which can be separated from the molten iron and can be dumped.
