Evaluation of Feasibility of Chemical Washing Treatment of Nickel in Deep-sea Mining Tailings by Aluminum Sulfate as Extractant

Objectives : The feasibility of chemical washing by Aluminum Sulfate(AS) was evaluated to treat harmful heavy metals such as Nickel(Ni) in deep-sea mining tailings. Korea(Rep. of) has acquired exclusive exploration rights for deep-sea mining areas and is developing commercial technologies to utilize actually deep-sea mineral resources. Transporting deep-sea mining tailings generated during development to land and use of hazardous chemicals in the marine environment are limited. As it is urgently required to develop remediation technologies considering these restrictions when treating deep-sea mining tailings at sea areas, the results of this research are presented as basic data for remediation technologies development by evaluating Ni extraction characteristic by elapsed time and concentration of additives.Methods : Manganese nodules samples prepared at 2%(w/v) using deionized water and manganese nodules(20 ~ 63 μm) and additives prepared under various concentration conditions were stirred and mixed under 16 elapsed time conditions. A solid phase and a liquid phase were separated, and harmful heavy metals extracted in the liquid phase were analyzed.Results and Discussion : As the elapsed time and the concentration of additives increased, the Ni removal rate also increased. Under the same EthyleneDiamineTetraacetic Acid(EDTA) concentration condition, the Ni removal rate increased as the AS additives concentration increased. 0.1 M EDTA and 1% AS mixed conditions showed the highest removal rate among all concentration conditions(27.5(±1.30) mg/L at 7 d).Conclusion It has been confirmed that the chemical washing treatment ability of AS compared to EDTA is effective without additional pH adjustment, and through the results of this research, it will be necessary to develop and optimize the actual remediation technologies using AS and process design.