Converter Magnesia-Carbon Bricks
Converter magnesia-carbon bricks are magnesia-carbon refractory products manufactured primarily from fused magnesia or high-purity sintered magnesia and high-purity graphite for use in converter linings. They typically contain a minimum of 95% MgO and 94% C. With phenolic resin or pitch as the binder, they are produced through batching, mixing, forming, and heat treatment. These bricks offer high-temperature resistance, strong slag resistance, and excellent thermal shock resistance. Antioxidants are generally added to mitigate oxidation.
Depending on the wear characteristics of different zones within the converter, magnesia-carbon bricks with specific properties are required:
The mouth and cone areas require products with strong thermal shock and slag resistance.
The trunnion areas require bricks with superior oxidation resistance.
The slag line requires outstanding slag corrosion resistance.
The charging side requires high-temperature strength and thermal shock resistance.
The bottom and hearth, especially in combined blowing operations, require premium-grade magnesia-carbon bricks with comprehensive performance.
Properties
Converter magnesia-carbon bricks are characterized by high-temperature resistance, strong slag resistance, excellent thermal shock resistance, and high hot strength. However, they are susceptible to oxidation during service, which can be mitigated by adding antioxidants. Their physical and chemical properties are listed in Table 1.
Table: Comparison of Magnesia-Carbon Brick Properties (Converter/EAF)
| Item | Japan – Shinagawa Refractories | Japan – Kurosaki Refractories | China – Ansteel Xihuo Refractories | China – Dashiqiao Refractories |
|---|---|---|---|---|
| Apparent Porosity / % | 2–4 | 2–4 | 2–4 | 2–4 |
| Bulk Density / g·cm⁻³ | 2.80–2.95 | 2.80–2.95 | 2.80–2.93 | 2.85–2.95 |
| Cold Crushing Strength / MPa | 35–45 | 30–45 | 30–45 | 30–50 |
| Hot Modulus of Rupture / MPa (at 1400°C) | 6–13 | 6–14 | 6–14 | 5–14 |
| MgO / % | 73–81 | 73–81 | 70–80 | 70–80 |
| F.C (Fixed Carbon) / % | 13–21 | 13–21 | 12–20 | 13–20 |
Manufacturing Process
The primary raw materials are fused magnesia or high-purity sintered magnesia, and high-purity graphite, with MgO ≥ 95% in the magnesia and C ≥ 94% in the graphite. Phenolic resin or pitch serves as the binder, along with suitable additives as required by service conditions. The finished bricks are produced through batching, mixing, forming, and heat treatment.
