초록 ▼

The process uses hydrochloric acid solutions to extract zinc from electric arc furnace dusts containing zinc oxide and zinc ferrite. To selectively leach zinc and minimize iron dissolution by precipitating as FeO.OH and Fe2O3, hot acid leaching with the aqueous solution containing 37 g/l-74 g/l HCl

The process uses hydrochloric acid solutions to extract zinc from electric arc furnace dusts containing zinc oxide and zinc ferrite. To selectively leach zinc and minimize iron dissolution by precipitating as FeO.OH and Fe2O3, hot acid leaching with the aqueous solution containing 37 g/l-74 g/l HCl and 104 g/l-270 g/l ZnCl2 is used. New dust is introduced to remove iron from the filtrate of the hot acid leaching. The zinc chloride solutions purified by activated carbon and metallic zinc powder is electrolysed in electrowinning cells which had cation exchange membrane to produce high purity zinc metal and to regenerate hydrochloric acid. Electrolysing an aqueous solution of zinc chloride with Zn concentration of 50-130 g/litre below 40.degree. C. in a cell divided by cation exchange membrane, whereby coherent zinc is yielded at the cathode with high current efficiency of exceeding 90%. HCl is directly regenerated with a very small loss below 2% and low energy consumption below 5.0 kWh/kg-Zn during Zn-electrodeposition at a cathodic current density in the range of 300-2000 A/m2, and a membrane current density in the range of 750-2000 A/m2. The spent electrolyte with 1-2N HCl is used to leach the residue in the hot acid leaching vessel.

대표청구항 ▼

1. A process for the leaching of electric arc furnace dust comprising a mixture of zinc, iron and lead oxides, the process comprising the steps of:leaching the dust with a leach solution containing hydrochloric acid and zinc chloride; and electrowinning of metallic zinc; wherein said leaching is car

1. A process for the leaching of electric arc furnace dust comprising a mixture of zinc, iron and lead oxides, the process comprising the steps of:leaching the dust with a leach solution containing hydrochloric acid and zinc chloride; and electrowinning of metallic zinc; wherein said leaching is carried out at a temperature of at least 80 degree Celsius and with concentrations of 37 g/l-74 g/l HCl and 104 g/l-270 g/l ZnCl2.