Removal of Ni(II) from strongly acidic wastewater by chelating precipitation and recovery of NiO from the precipitates

Xingyun Hu , Xin Yang , Xianjia Peng , Linghao Kong


Received September 25, 2020,Revised , Accepted December 14, 2020, Available online December 30, 2020

Volume 33,2021,Pages 365-375

Strongly acidic wastewater produced in nonferrous metal smelting industries often contains high concentrations of Ni(II), which is a valuable metal. In this study, the precipitation of Ni(II) from strongly acidic wastewater using sodium dimethyldithiocarbamate (DDTC) as the precipitant was evaluated. The effects of various factors on precipitation were investigated, and the precipitation mechanism was also identified. Finally, the nickel in the precipitates was recovered following a pyrometallurgical method. The results show that, under optimised conditions (DDTC:Ni(II) molar ratio = 4:1; temperature = 25 °C), the Ni(II) removal efficiency reached 99.3% after 10 min. In strongly acidic wastewater, the dithiocarbamate group of DDTC can react with Ni(II) to form DDTCsingle bondNi precipitates. Further recovery experiments revealed that high-purity NiO can be obtained by the calcination of DDTCsingle bondNi precipitates, with the nickel recovery efficiency reaching 98.2%. The gas released during the calcination process was composed of NO2, CS2, H2O, CO2, and SO2. These results provide a basis for an effective Ni(II) recovery method from strongly acidic wastewater.

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