Abstract
This paper presents the results of an experimental study on the extraction of KCl and the improvement of the zinc grade of secondary dust obtained from rotary-hearth-furnace secondary dust (RHF secondary dust) using alkali leaching (Na2CO3 solution) and evaporation–crystallization processes. The effects of the liquid–solid ratio and Na2CO3 content on the element leaching ratio in the alkali leaching process, as well as the effects of the volume–evaporation ratio and cooling temperature on KCl extraction in the evaporation–crystallization process, were investigated. The results showed that the optimum liquid–solid ratio was 6:1, and the optimum quantity of Na2CO3 was 1.5 times the basic quantity. The recovery ratio of zinc reached 95.23%, and the leaching ratio of K reached 79.01%. The experimental results of the evaporation–crystallization process demonstrated that the evaporation temperature was 80 °C, the volume evaporation ratio was 50%, the cooling temperature was 25 °C, and the mass fraction of K2O in the obtained crystals was 58.99%.
Highlights
Energy conservation and emission reduction are strongly advocated worldwide, and different kinds of dust produced by the steel industry during the smelting process are treated to achieve environmental friendliness and resource reuse
The quantity of Na2 CO3 to be consumed by zinc, magnesium, and calcium in the water immersion solution was calculated based on the proportion shown in chemical reaction
The X-ray diffraction (XRD) results on the composition of the elements in the rotary hearth furnace (RHF) secondary dust are shown in
Summary
Energy conservation and emission reduction are strongly advocated worldwide, and different kinds of dust produced by the steel industry during the smelting process are treated to achieve environmental friendliness and resource reuse. Wu [33] used the normal-pressure sulfuric-acid-leaching and goethite-oxidative hydrolysis method in processes such as iron and copper removal, zinc powder replacement, and electrowinning zinc extraction, in treating secondary dust and extracting dust from a lead furnace. The RHF secondary dust used by the two researchers had high zinc contents, and the zinc-containing phase are Zn2 SO4 and ZnO Their studies focused on the extraction of lead and zinc. Alkali leaching and evaporation–crystallization processes of the RHF secondary dust were experimentally investigated, to extract KCl and improve the zinc grade. RHFpurpose secondary of ZnO enters the residue because is insoluble theleaching Another of dust is treated through alkali leaching, the main elements in the leaching solution are sodium, alkali leaching is to make the alkali metal chloride enter the leaching solution.
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