Industrial refractory bricks are typically dried prior to firing using which production equipment or method in modern plants?

Introduction / Context:
Refractory manufacture involves shaping, drying, and firing. Proper drying prevents cracking, warping, and explosive spalling during subsequent high-temperature firing. Understanding where drying occurs in a continuous plant layout is part of basic refractory processing knowledge.

Given Data / Assumptions:

• Modern, continuous industrial operation rather than artisanal practice.
• Presence of continuous kilns with controlled thermal profiles.
• Need to remove mechanically held and capillary moisture uniformly.

Concept / Approach:

In many modern plants, tunnel kilns incorporate controlled zones: a drying or preheating section, a firing zone, and a cooling section. Green bricks pass continuously through, so drying is integrated. Rotary kilns are typically used for calcination or firing granular feeds (e.g., clinker, dead-burned magnesia), not for drying shaped bricks. Sun drying is inconsistent and unsuitable for quality-controlled production.

Step-by-Step Solution:

Verification / Alternative check:

Standard refractory plant flow diagrams show green bricks loaded onto cars entering the tunnel kiln where moisture is first driven off before high-temperature firing.

Why Other Options Are Wrong:

Rotary kilns: Suited to powders/aggregates and firing, not uniform drying of shaped bricks. Sun drying: Non-uniform, weather-dependent, and industrially unreliable. None of these: Incorrect because tunnel kilns are widely used.

Common Pitfalls:

Confusing stand-alone driers with the integrated drying zones of tunnel kilns; assuming artisanal methods apply to industrial production.

Final Answer:

Tunnel kilns (with drying/preheat zones)