Removal of Heavy Metals from Tailing in Citrate Solution with Ferric Chloride

Abstract

Leaching tests were performed in citrate solution with Fe 3+ to investigate the leaching behaviors of As, Zn, Pb, and Cu from tailings, which has been known as soil contaminant sources near abandoned mines. The combination of citrate and Fe 3+ was selected based on the previous study, which reported that the oxidants such as Fe 3+ was required to remove heavy metals from stable forms like sulfides because citrate could leach metals only in carbonate and oxide forms. The leaching efficiencies of heavy metals except As increased with increasing agitation speed, initial Fe 3+ concentration, temperature, but decreasing pulp density; e.g. the efficiencies of Zn, Pb, Cu were almost 100% in the 1 M citric solution with 3 M Fe 3+ at 400 rpm and 50°C with 0.25% pulp density within 3 hr, but 7.4% for As. The initial oxidation-reduction potential (vs Ag/AgCl) was reduced from 713.5 mV in FeCl 3 solution to 656.1 mV in citrate solution with FeCl 3 , which would inhibit the dissolution of As because As mineral such as arsenopyrite has high open circuit potential. These results indicate that As could be selectively left in the leach residue using citrate solution with Fe 3+ .

Leaching of Copper from Waste-Printed Circuit Boards (PCBs) in Sulfate Medium Using Cupric Ion and Oxygen

“…Conventional oxidants have disadvantages such as NO x gas emission due to HNO 3 leaching [33][34][35][36], increase in reagent consumption due to instability of H 2 O 2 [37,38], and requirement of additional separation process due to the use of Fe 3+ [38][39][40]. These drawbacks could increase the capital and environmental costs as mentioned above.…”

Effects of Ferrous Sulfate Addition on the Selective Flotation of Scheelite over Calcite and Fluorite

“…The number of abandoned metal mines in South Korea has been found to be 2089, and it was reported that 1268 of the abandoned metal mines have detrimentally affected the environments around the abandoned mines [1]. Sangdong mine is a representative scheelite mine in South Korea, and 12 million tons of tailings was generated during a 40-year operation after it had been abandoned [2,3].…”