Views: 1 Author: Site Editor Publish Time: 2024-09-09 Origin: Site
Ferrochrome is made from a mixture of chromite and iron in an electric arc furnace. Ferrochrome is widely used in the casting and steel industry and is also used for the production of low carbon structural steel, chromium steel, and alloy structural steel.
According to the different carbon content, ferrochrome alloy can be divided into high carbon ferrochrome, medium carbon ferrochrome, low carbon ferrochrome, and micro carbon ferrochrome.
Low carbon ferrochrome is a kind of ferrochrome with carbon content below 0.50, raw materials for the production of low carbon ferrochrome include silicon chromium alloy, chromite, limestone, and other metallurgy materials. Low carbon ferrochrome can be used in a variety of industries, it is a necessary additive in the production of stainless steel and special steel. It can improve the oxidation resistance and corrosion resistance of steel.
At present, there are two main smelting methods of low carbon ferrochrome, one is high carbon ferrochrome refining method, the other is electrosilicon thermal method.
High carbon ferrochrome refining method is divided into chromium ore refining high carbon ferrochrome and oxygen refining high carbon ferrochrome.
If we use chromium ore refining high carbon ferrochrome, the slag in the refining furnace has a larger viscosity and a higher melting point in the smelting process, the temperature must be very high, so the power consumption is high, the lining life is short, carbon content is not easy to come down. By contrast, oxygen smelting high carbon ferrochrome has a very large advantage, there are many benefits, such as high productivity, low production cost and high recovery rate.
The raw materials of oxygen top blow refining low carbon ferrochrome are high carbon ferrochrome, chrome ore, lime, and silicon chromium alloy.
The high carbon ferrochrome liquid of the converter usually requires a temperature between 1723 and 1873K. Molten iron contains more than 60% chromium, less than 1.5% silicon, and less than 0.036% sulfur. Chromium ore is used as slagging material, it is required that the content of SiO3 in chromium ore should be low, the content of MgO and Al2O3 can be appropriately high, and the viscosity can not be too large. Lime is also used as slagging material, and its requirements are the same as those of the electro-silicon thermal process. Si-Cr alloy is used for the reduction of high chromium slag at the later stage of blowing, generally using Si-Cr alloy powder under the screen after crushing.
The equipment used in the production of low carbon ferrochrome by oxygen blowing is a converter, so it is called the converter method. According to the different ways of oxygen supply, oxygen blowing can be divided into side blowing, top blowing, bottom blowing, and top-bottom blowing. The top blown converter method is used in China.
The oxygen blowing method is to blow oxygen directly into the high carbon ferrochrome liquid to decarbonize and make low carbon ferrochrome.
The main elements in high-carbon ferrochrome are chromium, iron, silicon, and carbon, which can be oxidized. The main task of oxidation and smelting of high carbon ferrochrome is to decarburize and preserve chromium. Chromium and iron make up more than 90% of the total alloy, so the chromium and iron are oxidized first when oxygen is blown into liquid high carbon ferrochrome, and then these oxides oxidize the silicon in the alloy. Due to the oxidation of chromium, iron, and silicon, the molten pool temperature increases rapidly, the decarbonization reaction develops rapidly, the higher the temperature is, the more conducive the decarbonization reaction will be, and it can also inhibit the oxidation of chromium, the carbon in the alloy can drop lower.
The electrosilicon thermal method is made by reducing chromium and iron oxides in chromium ore with silicon in silicon chromium alloy under the condition of making basic slag in the electric furnace.
Smelting Equipment And Raw Materials:
The smelting of low carbon ferrochrome by using the silicon thermal method is carried out in a fixed three-phase electric arc furnace, which can use a self-baking electrode, and the furnace lining is built with magnesium brick (dry lining). Short lining life is an important problem in low-carbon ferrochrome production. Because of the high smelting temperature (up to 1650 degrees Celsius), the lining life is generally short.
Raw materials of smelting low-carbon ferrochrome are chromium ore, silicon-chromium alloy, and lime. Chromium ore should be dry and pure block ore or refined powder, the higher the content of Cr2O3 is, the better; on the contrary, the lower the content of impurities (Al2O3, MgO, SiO2)are, the better. Phosphorus content should not be more than 0.03%, particle size should be less than 60mm for chromium ore. Si-Cr alloy should be crushed, particle size less than 30mm, without residue. Lime should be freshly burned and contain more than 85% CaO.
Conclusion
Low-carbon ferrochrome is not only widely used, but also its production process is very exquisite, which makes people feel how amazing the production method of low carbon ferrochrome is!
