Basic Information
Alias: high carbon ferrochrome, also known as big eye chromium.
Natural properties: natural blocks, each weight shall not be more than 15 kg, the size of less than 20*20mm ferrochrome block weight shall not exceed 5% of the total weight of ferrochrome.
Grade: High chromium with 50% chromium content as the benchmark assessment unit
Note: Material, particle size (50% chromium content as the benchmark assessment unit).
Application Areas:
High carbon ferrochrome is mainly used in stainless steel production, including 200 series stainless steel chromium content of about 16%, 300 series stainless steel chromium content of about 25%, 400 series stainless steel chromium content of about 14%. The 300 series stainless steel with the largest demand for ferrochrome is also the largest proportion of stainless steel production products.
Used as an alloying agent for ball steel, tool steel and high speed steel with high carbon content to improve the hardenability of steel, increase the wear resistance and hardness of steel; As an additive of cast iron, it can improve the wear resistance and hardness of cast iron, and make cast iron have good heat resistance. It is used as a chrome-containing raw material for the production of silicon chromium alloy and medium, low and micro carbon ferrochrome by slag free process. Chromium-containing raw material used for electrolytic production of chromium metal; Used as raw material for smelting stainless steel by oxygen blowing process.
Smelting process
The smelting methods of high carbon ferrochrome include blast furnace method, electric furnace method and plasma furnace method. Only special pig iron containing about 30% chromium can be made by blast furnace. As of 2012, high-carbon ferrochrome with high chromium content is mostly smelted in the ore furnace by the flux method.
The basic principle of electric furnace smelting high carbon ferrochrome is to use carbon to reduce chromium and iron oxides in chromium ore. The starting temperature of the carbon reduction of chromium oxide to Cr2C2 is 1373K, the starting temperature of the reaction to Cr7C3 is 1403K, and the starting temperature of the reaction to reduce chromium is 1523K. Therefore, when the carbon reduction of chromium ore, the carbide of chromium is obtained, not the metal chromium. The carbon content of ferrochrome depends on the reaction temperature. It is easier to generate carbides with high carbon content than carbides with low carbon content.
Raw material for smelting
The raw materials for smelting high carbon ferrochrome are chromium ore, coke and silica.
Chromium ore Cr2O3≥40%, Cr2O3/∑FeO≥2.5, S<0.05%, P<0.07%, MgO and Al2O3 content can not be too high, particle size 10 ~ 70mm, such as refractory ore, particle size should be small.
Coke is required to contain fixed carbon not less than 84%, ash less than 15%, S<0.6%, particle size 3 ~ 20mm.
Silica requires SiO2≥97%, Al2O3≤1.0%, good thermal stability, no soil, particle size 20 ~ 80mm.
