Recycling of Blast Furnace Dust in the Iron Ore Sintering Process: Investigation of Coke Breeze Substitution and the Influence on Off-gas Emissions

Abstract

In iron ore sinter plants blast furnace dust and other fine-grained residues which are rich in iron or carbon content are recycled. The carbon contained in the blast furnace dust can be used to replace coke breeze which is added to the charge as fuel for the sintering process. However, there is no information in the literature on the carbon replacement factor of fine-grained blast furnace dust. Nor is detailed information on the effect of blast furnace dust recycling on sinter plant off-gas emissions available. Recycling of blast furnace dust increases the zinc content of the sinter feed mixture. The degree of volatilisation of zinc in the sintering process and its discharge with the off-gas is of interest because zinc has to be limited in the burden of the blast furnace. The sinter pot tests performed in this study revealed that the carbon replacement factor of the carbon content in fine-grained blast furnace dust is very close to 1.0. The removal of sulphur contained in the sinter charge depends on the basicity of the sinter and on the total sulphur input. About 25% of the zinc contained in the blast furnace dust was volatilised in the sintering process and emitted with the off-gas.

Iron Ore Agglomeration Technologies

“…These new fuels are CO 2 -neutral, and lead to a significant reduction in SO X and NO X emissions. Other possibility is using blast furnace dust, as it has 24-40% carbon [69], although the amounts that are possible to recycle are limited fundamentally because of the zinc emissions.…”

Zinc recovery from metallurgical slag and dust by coordination leaching in NH3–CH3COONH4–H2O system

“…A zinc content that is over the prescribed limit might have a negative impact on blast furnaces, i.e. it might cause damage to refractory materials, shorten campaign life, cause operation difficulties and decrease the blast furnace productivity [ 3 – 5 ]. Lead and zinc smelting slag contains several poisonous elements such as arsenic (As), cadmium (Cd) and chromium (Cr), which makes it hazardous and unacceptable for stockpiling or landfilling [ 6 – 8 ].…”

Feasibility of Air Classification in Dust Recycling in the Iron and Steel Industry

“…However, limitations for recycling of these dusts usually arise from high Zn and Pb or alkali chloride content . The amount of Zn in the sinter plant feed is limited because Zn removal in the sinter plant is not efficient . Zn in the sinter causes problems in the downstream BF process, where it forms crusts in the upper part of the BF and accumulates in the furnace lining, which consequently deteriorates .…”