Optimizing Calcium Carbide Desulfurization in Steelmaking: A Case Study from Xinjiang Steel Plants

Optimizing Sulfur Removal in Steelmaking: A Case Study from Xinjiang Steel Mills

In modern steel production, sulfur control is critical for achieving high-quality output—especially in regions like Xinjiang where raw material variability and temperature fluctuations challenge consistent process performance. This article dives into the role of calcium carbide (commonly known as "electrocalcium") in desulfurization, drawing on real-world data from a leading steel mill in northern Xinjiang that achieved up to 35% improvement in sulfur reduction efficiency after implementing targeted operational adjustments.

How Calcium Carbide Works in High-Temperature Desulfurization

At temperatures above 1,500°C, calcium carbide reacts with dissolved sulfur in molten iron to form calcium sulfide (CaS) and carbon monoxide gas:

    CaC₂ + [S] → CaS + 2[C]
  

This reaction is highly exothermic and thermodynamically favorable under controlled conditions. However, its effectiveness hinges on three key factors: temperature stability, particle size distribution, and precise timing of injection.

Key Variables That Impact Efficiency

• Temperature Control: Optimal range: 1,450–1,550°C. Below 1,400°C, reactivity drops sharply—reducing desulfurization rate by up to 40%.
• Powder Size: Ideal particle size: 5–15 mm. Smaller particles (<5 mm) cause premature combustion; larger ones (>20 mm) reduce contact area and slow reaction kinetics.
• Timing of Injection: Best results when added during the early stage of tapping (within 2 minutes post-tap). Delaying beyond 5 minutes can decrease sulfur removal by over 25%.

These parameters were validated through a six-month pilot at the Xinjiang facility, which recorded an average sulfur level drop from 0.045% to 0.027% using optimized CaC₂ dosing protocols—without increasing energy consumption or processing time.

Real-World Challenges & Solutions

Common issues reported by mills include inconsistent slag formation, excessive gas generation, and uneven mixing. Our team observed that these often stem from improper storage (moisture absorption reduces reactivity), poor injection technique, or incorrect batch consistency. For example, one mill experienced frequent clogging due to oversized chunks—resolved by introducing a secondary crushing step before use.

By adopting a systematic approach—monitoring input quality, calibrating equipment, and training operators—we helped another plant reduce downtime by 30% while maintaining target sulfur levels below 0.03%.

What’s Next? Industry Trends & Innovation

The global steel industry is exploring advanced methods such as continuous injection systems and AI-driven predictive modeling for desulfurization. In China, pilot projects are testing nano-enhanced calcium carbide formulations that improve dispersion and reduce dosage requirements by up to 15%. These innovations align with sustainability goals—lowering emissions, reducing waste, and enhancing productivity.