| Since zinc metal has good wear resistance,calendering and corrosion resistance,the galvanizing process is often used in the surface protection of steel such as high-end automotive plates.However,China’s local zinc reserves are limited and have been depleted over the years,resulting in a high dependence on foreign raw materials.In order to cope with the tight supply of zinc resources,the recycling of secondary zinc resources is imminent.At the same time,the massive application of galvanized products has led to an increasing amount of galvanized steel scrap,resulting in a significant increase in the zinc content of circuit dust,and the comprehensive utilization of zinc-containing dust in a high quality manner has become a key issue for the sustainable development of the steel industry.In this paper,we propose a full life cycle recycling process of zinc,using zinc-containing dust as raw material and automotive sheet as substrate,using new green solvent for leaching and plating of zinc in zinc-containing dust,and the galvanized automotive sheet is used and scrapped as scrap steel raw material back to the steel production process again,thus realizing the full life cycle recycling of zinc in the steel production process.This process directly leaches and electroplates zinc from zinc-containing concentrates in the converter,or uses zinc chloride produced by chlorination as a zinc source for electroplating,eliminating the roasting of zinc oxide and smelting of zinc metal in the traditional process,greatly shortening the process,reducing energy consumption,and substantially increasing the added value of zinc-containing solid waste,with significant social and economic benefits.The main research contents of this paper are as follows:(1)Electroplated zinc coatings were successfully prepared on duplex steel automotive plates using choline chloride-urea-zinc oxide as the electrolyte,and the modification effects of two additives,niacin and ethylenediaminetetraacetic acid,on the electrochemical system of the solution and the prepared coatings were studied at the concentrations of 0.03,0.06 and 0.09 M.The addition of nicotinic acid to the system resulted in a large change in the deposition morphology of the plated layer,the grain size was refined,the surface density and flatness were improved,and the quality of the plated layer was improved to different degrees.The mechanical properties of the plated layer were improved the most when 0.03 M EDTA was added to the system,and the corrosion resistance of the plated layer was best when 0.06 M EDTA was added.(2)Electroplated zinc coatings were prepared on duplex steel by adding zinc chloride with different concentrations of additives(nicotinic acid and ethylenediaminetetraacetic acid)to the system using choline chloride-urea as a low eutectic solvent.The surface quality of the plated layers obtained in the pure system without additives was superior to the choline chloride-urea-zinc oxide system without additives.When nicotinic acid was added to the system,the plated layers changed from flaky crystals to amorphous bulk structures,and the mechanical properties of the plated layers obtained in the systems containing 0.03 and 0.06 M nicotinic acid were greatly improved,and the corrosion resistance of the plated layers containing 0.03 M nicotinic acid was the most superior year-on-year.The mechanical properties of the plated layers obtained in the systems containing 0.09 and 0.03 M ethylenediaminetetraacetic acid were improved,and the plated layers with 0.06 and 0.09 M additives had better corrosion resistance. |
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