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Keywords:

  • low-grade magnesite;
  • nesquehonite;
  • heavy metals wastewater;
  • removal efficiency;
  • precipitating agent

The preparation of nesquehonite and calcium carbonate using low-grade magnesite as a starting material, as well as the chemical treatment of copper-bearing heavy metal wastewater by using nesquehonite as a novel precipitating agent was investigated for the first time. The precipitation of copper with nesquehonite was shown to be successful in reducing the level of soluble copper in solution. The precipitation completion being reached within 30 min. The removal efficiency of copper was not affected by the addition of nesquehonite and a removal efficiency up to 99.97% was achieved as excess coefficient of nesquehonite was 0%. At this time, the precipitated amount of copper by nesquehonite was 459 mg/g. The residual copper concentration was 0.1 mg/L, and final pH value was 6.8, which met the Chinese discharge limit (0.5–2.0 mg/L, GB8978-1996) and the USEPA enforceable limit of 0.25 mg/L. The precipitate produced was very rich in copper, which occurred in the form of Cu(OH)2, CuCO3, Cu2(OH)2CO3, Cu3(OH)2(CO3)2, and Cu4(OH)6SO4·H2O. © 2012 American Institute of Chemical Engineers Environ Prog, 32: 543–546, 2013