What is Nitrided Ferro Chromium?
As an alloy additive, ferrochromium nitride is widely used in the smelting and production of stainless steel, heat-resistant steel, corrosion-resistant steel, alloy steel, and other special steels. At present, adding nitrogen to the production of nickel-containing austenitic stainless steel to reduce the nickel content has great economic benefits. The replacement of nickel with nitrogen will significantly improve the strength and corrosion resistance of the steel, while the plasticity remains the same.
In recent years, many domestic iron and steel enterprises are developing and producing high-strength, heat-resistant, and corrosion-resistant steel grades containing chromium and nitrogen. However, with changes in market demand, customers have a greater demand for ferrochrome nitride products with higher nitrogen and chromium content.
At present, the traditional production method of ferrochrome nitride is to pass nitrogen gas into ferrochrome and ferrochrome to carry out a compound reaction under certain conditions to obtain ferrochrome nitride. Specifically, there are two forms: the liquid nitriding method and the solid nitriding method. However, the traditional process of ferrochromium nitride is long and the cost of raw materials is high.
New Production Method of Nitrided Ferro Chromium
The Raw Materials
Aluminium Chromium Slag: Aluminum chromium slag is a by-product derived from the smelting of metallic chromium by the aluminothermic reduction reaction. When metal chromium is smelted, the reduction reaction between metal aluminum and industrial chromium oxide is used to produce metal chromium. Metal aluminum powder and Cr2O3 undergo a violent chemical reaction in a molten state. Cr2O3 solid solution, forming aluminum chromium solid solution, that is, aluminum chromium slag.
Usually, 15 tons of chromium slag are discharged for every ton of metal chromium produced, and the main components of aluminum chromium slag are Al2O3 and Cr2O3. Aluminum chromium slag is harmful to the ecological environment to some extent, but if it is properly managed, it is an available resource.
The Production Process of Nitrided Ferro Chrome Made from AlCr Slag
- Crushing the aluminum chromium slag to obtain aluminum chromium slag particles; mixing the aluminum chromium slag particles with petroleum coke particles and adding them to the electric arc furnace.
- After starting the electric arc furnace, the temperature near the graphite electrode rises rapidly. When the temperature reaches 2039K, Cr7C3 begins to melt, gather, and sink and finally obtains Cr7C3 blocks. It is crushed and ball-milled into Cr7C3 powder, and a certain amount of Fe3O4 and Cr7C3 powders are selected. well, mixed.
- Put the above mixture into the furnace cavity of the vacuum induction heating furnace, and turn on the vacuum system, when the vacuum degree reaches 10Pa, turn on the heating system, the heating rate is 50°C/min, when the temperature reaches 1250°C, start constant temperature, and then heat to 1350°C, start constant temperature, and observe the vacuum value at the same time, at this time, Cr7C3 reacts with Fe3O4 at high temperature to form ferrochromium and carbon monoxide.
- The generated carbon monoxide is continuously discharged under vacuum or negative pressure until the vacuum degree is maintained in the range of 10-20Pa, and the constant temperature is continued. After ensuring sufficient reaction, turn off the vacuum system. Then fill in high-purity nitrogen from the filling valve. When the pressure of nitrogen reaches 0.2Mpa, stop the inflation and continue to keep the temperature at 1350°C. Then, when the furnace cools down to below 100°C, take it out of the furnace, and you can get a nitrogen content of 5 %-6% ferrochromium nitride.
The Advantages This Ferrochromium Nitride Production
1. The new production method uses the by-product aluminum chromium slag formed by metal chromium smelting as raw material, which solves the problem of solid waste discharge, realizes the resource recycling of aluminum chromium slag, saves resources, and is environmentally friendly. The conversion of 40,000 tons of aluminum chromium slag is calculated, and 50,000 tons of bauxite ore and 10,000 tons of chrome ore can be saved every year. The products produced meet the requirements of high-quality ferrochromium nitride materials and can be used in electric furnaces and oxygen converters to smelt nitrogen-containing steels.
2. The price of raw materials is low, and the production cost is low, which is 20%-30% lower than conventional methods.
3. The process is relatively simple, the production efficiency is high, and the impact on the environment is small.
4. The product quality is stable, and the nitrogen content is high, which can reach 5%-6%.