Hydro-chemical conversion of galena in FeCl3-KCl solution

The behaviours of complexation and dissolution of PbCl2 on the surface of galena were investigated to explore the process of hydro-chemical conversion of galena (PbS) in chloride media. By means of solution chemistry calculation, the production and dissolution of the products PbCl2 were studied. And the passivation of the galena was studied by Tafel curve. The results show that PbCl42− is the main form of PbCl2 presented in the saturated potassium chloride (KCl) solution. The PbCl2 crystal is easy to precipitate when the total concentration of chloride ion ([Cl−]T) is equal to 0.92 mol/L, and it is inclined to dissolve when [Cl−]T is more than 0.92 mol/L. The chloride complexing reaction rate strongly depends on the Fe3+ion concentration when it is less than 6×10−4mol/L, while passivation occurs on the surface of the electrode when Fe3+ concentration is larger than 6×10−4mol/L. The reaction rate increases obviously when KCl is added, since the activity of Cl− increases; thus accelerates the dissolution of PbCl2.