IS ZINC A PROBLEM FOR THE RECYCLING OF STEELMAKING BY-PRODUCTS IN THE BLAST FURNACE?

摘要

Many recycling processes of steelmaking byproducts, such as dusts and sludges, have been proposed in recent years, in opposition to the use of the blast furnace as a recycling equipment. There are two main reasons for this: the high economic and environment necessities for recycling and the well known problems that volatile elements, such as zinc, cause to the blast furnace operation. However, new processes, involving metallurgical operations that the steel industry is not used to, are not well accepted by the steelmakers. Besides, they represent high risk and investment. A thermodynamic analysis of the zinc contained in the dust from the BOF has shown that, by changing the blast furnace operation, it is possible to charge up to 30 kg of Zn per ton of hot metal, allowing an efficient and economical recycling of this material. As opposed to the other processes, this proposal is a well-known operation for the steel industry, and therefore represents reduced risk and investment. However, due to the required modifications to the process and equipment, small-scale sinter plant and blast furnace seems to be more appropriate as a recycling equipment.