Abstract
Large amounts of pickling liquor are produced during the pickling of iron and steel. The Venturi reactor is used during the pyrolysis of pickling liquor to prepare high-purity Fe2O3 particles. Changing the pyrolysis conditions will affect the purity and concentration of Fe2O3 particles. In this paper, physical experiments and numerical simulations were carried out to study the effect of pyrolysis conditions on the Fe2O3 particles, including the pyrolysis temperature, the FeCl2/FeCl3 ratio in the pickling liquor, and the citric acid ratio. The results showed that a product with a higher purity, better crystallinity, and greater concentration was obtained at 923 K. Further increasing the temperature did not change the concentration of Fe2O3 particles. When the ratio of FeCl2/FeCl3 in the pickling liquor was 1:1.5, the maximum concentration of Fe2O3 particles at the outlet was obtained. When the added proportion of citric acid was 1:1, the particle size distribution was more uniform, and when the added proportion was 1:2.5, the maximum concentration of Fe2O3 particles at the outlet was achieved.
Highlights
The dense Fe2O3 formed on the surface of steel products during their production requires pickling, which produces 1.2–2 tons of pickling liquor per ton of steel (Zhang et al, 2014; Wang and Ma, 2017; Wang et al, 2020)
This paper used a combination of experiments and numerical simulations to study the effects of temperature, pickling liquor composition, and citric acid ratio on the composition and morphology of Fe2O3 particles obtained at the outlet of a Venturi reactor
The furnace temperature was set to 773, 873, 923, 973, 1023, and 1123 K, and the pyrolysis products Fe2O3 were collected at the cyclone separating unit
Summary
The dense Fe2O3 formed on the surface of steel products during their production requires pickling, which produces 1.2–2 tons of pickling liquor per ton of steel (Zhang et al, 2014; Wang and Ma, 2017; Wang et al, 2020). In large iron and steel enterprises, the Ruthner spray pyrolysis method (Qi, 2006; Deng et al, 2007; Bian et al, 2015) is primarily used to process waste acid, in which FeCl2 and FeCl3 react with H2O and O2 to produce HCl and Fe2O3 particles. This process has technical barriers and high investment costs. This paper used a combination of experiments and numerical simulations to study the effects of temperature, pickling liquor composition, and citric acid ratio on the composition and morphology of Fe2O3 particles obtained at the outlet of a Venturi reactor. Right was the free outlet, and the section directly below the reactor in the vertical direction was the waste acid solution inlet
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