Behavior of Chromium, Nickel, Lead, Zinc, Cadmium, and Mercury in the Blast FurnaceA Critical Review of Literature Data and Plant Investigations

Blast furnaces have a huge turnover of materials. Besides the transformation of the main elements iron and carbon, a large variety of other elements (present at low concentrations in different input materials) are undesirably inserted into blast furnaces. Heavy metals, such as chromium, nickel, lead, zinc, cadmium, and mercury, belong to these unwanted elements that are inserted. In the present paper, the behavior of these heavy metals in the blast furnace process has been investigated in detail, since they may influence the quality of the product, the byproduct, the process stability, and the environmental impact of hot metal production (e.g., emissions of heavy metals). Thereto, a detailed literature review has been carried out and its results have been subsequently compared with long-term investigations (over 3 years) conducted at an Austrian blast furnace. The results of the study indicate that nickel and chromium are very affine to the hot metal and thus to a large extent (>84%) transferred into it. Contrary to this, mercury and cadmium are mainly discharged via the top gas dust (>87%) and thus accumulate in the residues of the top gas cleaning system. For zinc and lead, no main discharge route could be detected. The results for lead and zinc varied considerably, which indicates the dependency of their transformation on the process conditions.