Analysis of destructive effect of Zn on carbon brick and way of Zn into carbon brick

The service life of a blast furnace depends largely on the degree of damage to the carbon brick in the hearth. Carbon brick and ramming material in the hearth of a 1780 m³ blast furnace after shutdown were sampled and investigated. It was found that the substances in the cracks of the carbon brick near and above the taphole were ZnO and Zn₂SiO₄, whereas the substances in the cracks of the carbon brick below the taphole were ZnS. The reaction of Zn with CO, SiO₂, and FeS generates ZnO, Zn₂SiO₄, and ZnS, resulting in volume expansion, which is an important reason for the cracking of carbon brick. Simultaneously, several obvious Zn vapor flow channels were found in the ramming material, through which Zn vapor could enter the carbon brick, causing damage to the carbon brick. Increasing the compactness of the ramming material is beneficial to preventing Zn vapor from entering the carbon brick through the voids in the ramming material, reducing the destructive effect of Zn on the carbon brick and further extending the service life of the blast furnace.