The Role of Sustainable Refractory Materials in Reducing Energy Consumption and CO₂ Emissions in Steelmaking Tundishes
In recent years, rising energy costs, stricter environmental regulations, and carbon emission reduction targets have posed significant challenges to the steel industry. One of the process units with substantial potential for energy optimisation and CO₂ reduction is the tundish in continuous casting. Selecting the appropriate refractory lining system for the tundish can directly influence fuel consumption, operational costs, turnaround time, and overall process sustainability.
What Is a Tundish and Why Is It Critical in Steelmaking?
The tundish is an intermediate vessel positioned between the ladle and the mould during continuous casting. Its primary function is to distribute molten steel evenly to the moulds while also performing important metallurgical tasks such as inclusion flotation and flow control.
Structurally, a tundish consists of a steel shell and anchoring system, insulation layers, a permanent lining, and a sacrificial wear lining. Since the tundish is the most frequently relined vessel in a steel plant, any improvement in refractory design or installation practice can have a substantial cumulative impact on energy consumption and greenhouse gas emissions.
Energy and Environmental Challenges in Tundish Lining
Conventional tundish lining concepts, particularly for permanent linings, often require long and carefully controlled drying and preheating procedures using natural gas. These steps are not only time-consuming but also lead to significant energy usage and direct CO₂ emissions.
With increasing natural gas prices and the growing relevance of carbon pricing mechanisms, reducing drying time and heat-up temperature has become a key objective for steel producers aiming to improve both cost efficiency and environmental performance.
What Are Sustainable Refractory Materials?
Sustainable refractories are materials that combine reliable thermomechanical performance with reduced environmental impact throughout installation and operation. In tundish applications, sustainable refractory solutions typically aim to:
- Lower energy demand during drying and preheating
- Reduce direct and indirect CO₂ emissions
- Shorten tundish turnaround and installation time
- Increase operational availability and lining lifetime
These goals are commonly achieved by using sol-bonded permanent linings and cold-setting wear lining technologies.
The Role of Permanent Lining in Energy Reduction
The permanent lining represents the final protective barrier between molten steel and the tundish steel shell. Traditionally, low-cement castables (LCCs) have been widely used for this purpose. However, due to their hydration-based bonding mechanism, LCCs require slow and energy-intensive drying schedules to safely remove physically and chemically bound water.
In contrast, modern sol-bonded castables utilise a different bonding concept that allows moisture to be released at significantly lower temperatures. This results in:
- Substantially shorter drying times
- Significant reductions in natural gas consumption
- Improved tundish availability and flexibility
As a result, sol-bonded permanent linings are increasingly regarded as a key enabler for sustainable tundish operation.
Wear Lining Technologies and the Elimination of Drying
The wear lining is directly exposed to molten steel, slags, and thermal cycling and is therefore replaced after each casting sequence. Conventional solutions such as slurry gunning mixes typically require additional drying and preheating steps prior to casting.
Advanced cold-setting wear lining technologies harden through a chemical reaction at ambient temperature and do not require external heat input. By eliminating the drying step, these systems dramatically reduce energy consumption, CO₂ emissions, and overall tundish preparation time.
Direct Impact of Refractories on CO₂ Emissions
On average, the combustion of natural gas results in approximately 2 kg of CO₂ emissions per cubic metre consumed. Consequently, any reduction in drying or preheating energy directly translates into lower greenhouse gas emissions.
Industrial evaluations have shown that optimised tundish lining concepts using sustainable refractories can:
- Reduce natural gas consumption by more than 70%
- Lower both energy costs and carbon-related expenses
- Improve the overall efficiency of continuous casting operations
Conclusion
As one of the most frequently relined vessels in a steel plant, the tundish plays a crucial role in strategies aimed at reducing energy consumption and CO₂ emissions. The use of sustainable refractory materials enables steel producers to significantly lower fuel usage, shorten turnaround times, and reduce operational costs while maintaining high process reliability. Adopting such lining concepts represents an important step towards green steel production and long-term industrial sustainability.
Source: RHI