Refractory materials generally refer to inorganic non-metallic materials with a refractoriness of more than 1580℃. They can withstand the physical and chemical effects of gases, dust, slag, liquid metal and other substances, and have a certain strength of masonry and knotting performance. In Chinese, refractory material, “耐火材料” is simply called “耐材”. If refractory materials are crushed, ground, screened, and mixed, and mixed with a small amount of additives that serve as both lubricants and binders, pressed into shape, dried, calcined or melted, the resulting products are called refractory products. Since insulation materials are quite similar to refractory materials, they are also introduced here.
Main technical requirements for refractory materials (products) in electric furnace steelmaking
Electric furnace steelmaking has the following technical requirements for refractory materials (products):
- Refractory materials (products) should have a sufficiently high refractoriness.
- Refractory materials (products) should have a high load softening start temperature to ensure that they can work under high temperature loads and resist the erosion of molten steel.
- Refractory materials (products) should have good thermal stability and be able to withstand rapid changes in temperature.
- Refractory materials (products) should have sufficient chemical stability to resist chemical erosion by molten steel, slag, furnace gas, dust, etc. at high temperatures.
- Refractory materials (products) should have high mechanical strength, low thermal conductivity and electrical conductivity at high temperatures.
- The physical and chemical indicators, shape and size of refractory products should comply with relevant standards. It is strictly prohibited to use those with cracks, melt holes, or irregular bricks, or those with serious damage to the brick body and brick teeth.
Classification of refractory materials for electric furnace steelmaking
- Refractory materials for furnace lining
- Bricks for pouring
- Bricks for ladle
- Bricks for furnace roof
- Lightweight insulation bricks
- Breathable bricks
- Some other refractory mud materials, etc.
Introduction to commonly used refractory materials
- Insulation materials
Common insulation materials for electric furnace steelmaking include asbestos board, asbestos rope, slag wool, diatomaceous earth bricks or other lightweight clay bricks. Their main function is to reduce heat loss, and they are also used for thermal insulation protection, such as preventing equipment systems from burning out or scalding. Therefore, the requirements for the refractoriness, thermal stability, mechanical strength and slag resistance of insulation materials are not high, but the thermal conductivity should be as low as possible.
- Refractory products
In electric furnace steelmaking, refractory products are mainly used for ladle and pouring system, electric furnace lining and steel spout. Due to different parts and working conditions, the requirements for the performance of refractory products are also different, that is, different parts should use different refractory products.
- Knotted refractory materials for furnace lining
The main knotted refractory materials for alkaline furnace lining are magnesia and dolomite.
Dolomite has high refractoriness, good slag resistance and thermal stability, and has large reserves and low prices. Although it has the weakness of easy water absorption and easy powderization, it is still a substitute for magnesia.
- Refractory clay
In metallurgy, except for special circumstances, the masonry, padding and caulking of general refractory products require homogeneous refractory clay to avoid mutual corrosion at high temperatures, and require high refractoriness and certain ability to resist high temperatures. The refractory clay commonly used in electric furnace steelmaking is clay, high alumina, magnesia and siliceous. It is mixed with a binder when used and prepared at any time.
- Refractory concrete
Refractory concrete is a relatively new type of refractory material, characterized by simple production, convenient masonry and knotting, and high service life. However, refractory cement has a short shelf life and is very easy to deteriorate, so the date the refractory cement enters the factory must be coordinated with the construction date.
