Recovery of Zinc From Zinc Dross Using Pyrometallurgical and Electrochemical Methods

Abstract

R ECOVERY of zinc from its dross was investigated using electrochemical and pyrometallurgical methods. Almost 100% pure zinc was obtained using these methods. A small bench scale system for the investigating the recovery of zinc using pyrometallurgical methods was developed. The system based on the evaporation of zinc (in the dross) at 1050 o C and condensing zinc vapors into pure zinc in a separate crucible. Almost pure Zn (99.95%) is obtained using this method. Recovery of zinc was also performed using electrowinning from the acidified zinc sulfate bath and electrorefining of zinc dross anodes in the alkaline ammonia bath. In either method different parameters including current density and deposition time were addressed. Zinc powder of almost 100% purity was obtained.

Zinc Evaporation from Brass Scraps in the Atmosphere of Inert Gas

“…The data presented in this figure show that the rate of the process of zinc evaporation was far higher in the helium atmosphere compared to the carbon monoxide or argon atmospheres, and this rate was higher in the carbon monoxide atmosphere compared to the argon atmosphere. It should be noted that the coefficients of zinc vapour diffusion in the analysed gas atmospheres are arranged in a series similar to that of the estimated values of the evaporation rate as follows: D Zn-He > D Zn-CO > D Zn -Ar (15) In paper [40], the effects of the type of applied gas atmosphere on the rates of molybdenum evaporation in helium, argon and nitrogen are demonstrated. Here, the highest evaporation rate was also achieved in the helium atmosphere, which is illustrated in Figure 14.…”

“…DZn-He > DZn-CO > DZn-Ar (15) In paper [40], the effects of the type of applied gas atmosphere on the rates of molybdenum evaporation in helium, argon and nitrogen are demonstrated. Here, the highest evaporation rate was also achieved in the helium atmosphere, which is illustrated in Figure 14.…”

“…Cupriferous wastes are, e.g., casting waste, copper smelting dusts or flotation tailings. In this area, the offered solutions with regard to zinc removal from these wastes are primarily based on pyrometallurgical [ 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 ] and hydrometallurgical [ 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 ] processes. In hydrometallurgical processes, various leaching materials are applied such as sulphuric acid, hydrochloric acid, acetic acid or ammonia solutions.…”

Theoretical and Practical Evaluation of the Feasibility of Zinc Evaporation from the Bottom Zinc Dross as a Valuable Secondary Material

“…Bottom zinc dross from the hot-dip galvanizing process was put under investigation in several studies. Bottom zinc dross was investigated using electrochemical and pyrometallurgical methods by Ghayad et al [33]. Dross containing 96.18% of zinc was dissolved in concentrated sulfuric acid to create zinc sulfate solution (100 g Zn/L).…”