Refractory processing — Typical firing temperature range for magnesite (MgO) bricks is approximately which of the following (°C)?
-
A800-1000
-
B1000-1200
-
C1600-1800
-
D2400-2600
Answer
Correct Answer: 1600-1800
Explanation
Introduction:Magnesite (MgO) bricks are basic refractories used in steelmaking and other high-temperature basic environments. Their manufacturing involves high-temperature firing to achieve desired densification, strength, and slag resistance. The question focuses on the representative firing temperature range.
Given Data / Assumptions:
- Product: fired magnesite refractory (not chemically bonded cold-set types).
- Objective: sufficient sintering and densification for service in steel and cement kilns.
- Temperatures listed are broad ranges.
Concept / Approach:Sintering of magnesia grains requires high temperatures because MgO has a very high melting point (~2800°C) and relatively sluggish diffusion at lower temperatures. Industrial firing for standard dense magnesia bricks commonly occurs around 1600–1800°C to achieve proper microstructure and bond.
Step-by-Step Solution:Consider MgO properties: high melting point implies high sintering temperature.Industrial practice: kilns for MgO bricks operate ~1600–1800°C for adequate densification.Exclude too-low ranges (≤1200°C): insufficient sintering.Exclude 2400–2600°C: technically unnecessary and uneconomical for standard products.
Verification / Alternative check:Textbook firing schedules and vendor datasheets typically cite 1600–1800°C for ordinary fired magnesite bricks; special ultra-dense grades may use higher but still below 2400°C.
Why Other Options Are Wrong:
- 800–1000°C / 1000–1200°C: Too low for MgO sintering.
- 2400–2600°C: Excessive; not standard practice for typical fired bricks.
Common Pitfalls:Confusing firing temperatures of clay/silica refractories with basic magnesia; assuming “higher is always better” without considering energy and microstructural goals.
Final Answer:1600-1800