Behavior of Copper Dissolution in an Ammonia Solution Containing Ammonium Chloride or Sulfate

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The leaching solution was prepared from either copper chloride (NH₃ solution and NH₄Cl) or copper sulfate (NH₃ solution and (NH₄)₂SO₄). Copper plates were immersed in these solutions and stirred at 298~353 K. The leaching speed of copper was calculated from the obtained weight loss data. Moreover, influence concentrations of NH₃ and NH₄Cl were investigated for the dissolution of copper.
The dissolution of copper was investigated in solutions containing differing concentrations of NH₃ and NH₄Cl. Insolutions of NH₃ (1~6 kmol m^-3) and 1 kmol m^-3 NH₄Cl (0~3 kmol m^-3) containing 0.5 kmol m^-3 Cu(II) at 313 K, leaching speed increased with increasing NH₃ concentration up to 2 kmol m^-3 and NH₄Cl concentration up to 0.5 kmol m^-3. Leaching speed of copper at 600 rpm was calculated to be 3.98 kg m^-2 h^-1 at 353 K in a solution of 4 kmol m^-3 NH₃ and 1 kmol m^-3 NH₄Cl containing 0.5 kmol m^-3 Cu(II). The leaching speed of 3.98 kg m^-2 h^-1 was faster than the 1.65 kg m^-2 h^-1 obtained at 600 rpm in a solution of 7 kmol m^-3 NH₃ and 1 kmol m^-3 (NH₄)₂SO₄ containing 0.5 kmol m^-3 Cu(II) at 353 K. The relationships between V^2/3 (stirring speed) and R (leaching speed) were approximately linear in both baths. On the other hand, the elevated bath temperature increased the leaching speed in a solution of 7 kmol m^-3 NH₃ and 1 kmol m^-3 (NH₄)₂SO₄ containing 0.5 kmol m^-3 Cu(II). The leaching speed of copper in an ammonia solution containing ammonium chloride was higher than that in an ammonia solution containing ammonium sulfate.