Method for inhibiting abnormal expansion of super-high-grade pellets through gradient heating reduction of hydrogen-based shaft furnace

By using gradient heating reduction method in hydrogen-based vertical furnaces, the reduction process of ultra-high grade pellet ore is regulated, the problem of abnormal expansion of pellet ore during hydrogen-based vertical furnace reduction is solved, the production of high-purity direct reduction iron is achieved, and the energy consumption of smelting is reduced.

CN120099245AActive Publication Date: 2025-06-06CENT SOUTH UNIV
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Patent Information

Application Number
CN202510569918.6
Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
Filing Date
2025-05-06
Publication Date
2025-06-06
Estimated Expiration
2045-05-06

AI Technical Summary

Technical Problem

Ultra-high grade pellet ore has abnormal expansion problems during the hydrogen-based vertical furnace reduction process, resulting in low strength of the pellet and difficult to meet production requirements.

Method used

The gradient heating reduction method is adopted to regulate the reduction process of ultra-high-grade pellet ore in a hydrogen-based vertical furnace, and the heating rate and temperature of different reduction zones are controlled, thereby inhibiting the expansion caused by crystal form transformation and iron whisker growth.

Benefits of technology

Without reducing the original iron grade of the pellet ore, the maximum expansion rate of the pellet ore in the hydrogen-based vertical furnace reduction process is reduced to less than 15%, and high-purity direct reduction iron with qualified quality indicators is produced to reduce the energy consumption of subsequent electric furnace smelting.

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Abstract

The invention discloses a method for inhibiting abnormal expansion of ultrahigh-grade pellets through gradient heating reduction of a hydrogen-based shaft furnace, and belongs to the technical field of direct reduction iron production. The method comprises the following steps: continuously adding ultrahigh-grade pellets from the top of a hydrogen-based shaft furnace, and sequentially passing through a first heating reduction zone (the heating speed is 10-20 DEG C / min, and the temperature reaches 900-930 DEG C), a second heating reduction zone (the heating speed is not less than 30 DEG C / min, and the temperature reaches 990-1020 DEG C), a constant-temperature reduction zone and a cooling zone of the hydrogen-based shaft furnace to obtain the direct reduction iron. The method is suitable for the hydrogen-based shaft furnace with various reducing atmospheres, the maximum reduction expansion rate of the ultrahigh-grade pellets in the reduction process of the hydrogen-based shaft furnace can be smaller than 15% on the premise that the original iron grade of the pellets is not reduced, high-purity direct reduction iron with qualified production indexes is produced, and reduction of follow-up electric furnace smelting energy consumption and the molten iron refining process are facilitated.
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