Synthetic zinc ferrite reduction by means of mixtures containing hydrogen and carbon monoxide

Abstract

Solid waste generation is one of the main problems in the steelmaking process. One of the most problematic waste products is the electric arc furnace dust, which is a by-product rich in iron and zinc and is present as zincite (zinc oxide) or franklinite (zinc ferrite). This work focuses on the reduction kinetics of synthetic zinc ferrite by gases containing hydrogen and carbon monoxide. This process was examined via forced stepwise isothermal analysis. The test was conducted at temperatures ranging from 500 to 950°C. Reduction of zinc was accomplished using a mixture of hydrogen and carbon monoxide in order to simulate reformed natural gas. The results indicated that reduction of zinc ferrite occurred in two stages (550-750°C and 800-900°C). The first stage was characterized by iron oxide reduction, where a mix control between nucleation and diffusion was determined. The apparent activation energy obtained was 71.5 kJ mol -1 . The second stage was characterized by zinc oxide reduction, where the controlling mechanism was identified as a mixed control between diffusion and phase boundary reaction. The apparent activation energy was 135.5 kJ mol -1 . The formation of a dense layer of metallic iron around the unreacted core may have caused the apparent activation energy to increase.

Highly efficient multi-metal catalysts for carbon dioxide reduction prepared from atomically sequenced metal organic frameworks

“…This is also consistent with the peak broadening and splitting in the PXRD patterns of the corresponding samples, since small changes in lattice parameters are expected for different degree of calcium substitution of the manganese sites in MnO. EDS analysis did not show any presence of zinc in the catalysts, indicating that any zinc species formed during the reaction are reduced and sublimated during the reaction [35,36]. Ultra-small nanoparticles covering the surface of MnO are also observed, which correspond to metallic cobalt, as confirmed by EDS analysis.…”

Selective Zinc Removal from Electric Arc Furnace (EAF) Dust by Using Microwave Heating

“…In general, the reduction and the recovery of zinc increase with the rising temperatures. The results indicated that the temperature of 750 °C was insufficient for the volatilization of zinc [26,27]. Increasing the temperature to 850 °C resulted in increased the zinc removal rate from 22.11 to 63.39%.…”

Reduction of electric arc furnace dust pellets by simulated reformed natural gas

“…It was also observed iron peaks, which suggests reduction of wustite to iron. Meanwhile, it has been reported [16] for temperatures higher than 800°C zinc oxide is also reduced to metallic gaseous zinc, which indicates zinc oxide reduction in this step. Figure 5c shows peaks of zinc oxide, wustite and iron in the third stage (850-950°C), which indicates that both zinc oxide and wustite are still being reduced at this stage.…”

“…3 [13][14][15]. In a previous paper [16], it was studied the reduction of synthetic zinc ferrite pellets by CO and H 2 mixture. It was noted that synthetic zinc ferrite was reduced to zinc oxide (ZnO) and iron oxide (Fe 3 O 4 ) at temperatures lower than 550°C.…”