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%.