Efficient Zinc Removal from Blast Furnace Sludge Using Choline Chloride–Malonic Acid: Towards Sustainable Recycling of Iron Extraction Waste
Abstract
Chemical components of blast furnace sludge (BFS) of iron blast furnaces
become a recyclable raw material in the furnace when a few contents
including zinc (Zn) are selectively removed. Out of four deep eutectic solvents
(DES) preselected from the literature for their potential selective Zn leaching
performances, choline chloride–malonic acid was determined to be the most
efficient DES for its efficiency in removing Zn from BFS in the presence of iron
(Fe). Further preliminary tests were conducted via iterations of leaching
parameters to determine their individual effects on the leaching efficiencies
for Zn, Ca, and Fe. Parameters like DES concentration, leaching period, and
solid/liquid ratio were found to be the most accountable, as agitation speed and
temperature showed only a slight influence on the efficiencies. For a maximum
Zn removal of about 85% with the least amount of Fe of around 15%, the
empirical parameters without any extra optimization were estimated to be 30
vol.% malonic acid concentration, ¼ (g/mL) solid/liquid ratio, 100 rpm agitation
speed, 60 C leaching temperature, and 3.0 h leaching period.