Abstract
Electric arc furnace dust (EAFD) is an important secondary resource for the zinc industry. The most common process for its recycling is the pyro-metallurgical treatment in the Waelz process. However, this process focuses on the recycling of the zinc, whereas the recovery of other metals from the EAFD—such as iron and other alloying elements—is neglected. An up-to-date version of reprocessing can involve multi-metal recycling by means of a metal bath containing carbon. The use of a liquid iron alloy requires a higher processing temperature, which enables the reduction and melting of iron oxides as well as other compounds occurring in the dust. Furthermore, the Zn yield is higher and the reduction kinetics are faster than in the Waelz process. This paper is only focused on the zinc reduction in such a metal bath. In order to determine the influence of the carbon content in the molten metal on the reduction rate, experiments were carried out on the reduction behavior of zinc oxide using a synthetic slag. This slag, with a basicity B2 = 1, was applied to an iron bath with varying carbon contents. (0.85%, 2.16%, 2.89%, and 4.15%) The decrease in the zinc oxide concentration was monitored, along with the reaction rates calculated from these data. It was found that the reaction rate increases with rising carbon content in the melt.
Highlights
Steel mill dusts with high zinc content, occurring during the production of carbon steel, are a well-known secondary resource for the zinc industry
Since the crucible was not sealed, the produced gaseous zinc was directly re-oxidized in the furnace atmosphere, and zinc oxide (ZnO) was transferred into the off-gas system
An increased carbon concentration in the molten iron led to a faster decrease in ZnO in the first six minutes of the test
Summary
Steel mill dusts with high zinc content, occurring during the production of carbon steel, are a well-known secondary resource for the zinc industry. It is important to recycle the dust in a proper way. Despite considerable disadvantages, such as low product quality and high amounts of residual waste, the Waelz process has dominated the recycling of these dusts for several decades. A suitable concept could be the recycling of the EAFD via an iron bath containing dissolved carbon. Process developments such as the PIZO, ESRF, and 2sDR processes make use of this technology [1–5]
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