Efficient Pb removal through the formations of (basic) carbonate precipitates from different sources during wet stirred ball milling with CaCO.

Calcium carbonate (CaCO) may be used for lead removal. However, due to compact structure and high crystallinity of CaCO, the utilization of CO is low and Pb removal only stays at the extent of physical adsorption and surface precipitation. In this research, a wet stirred ball milling process was introduced to induce nearly stoichiometric reactions between lead salts of nitrate, chloride or sulfate with CaCO by consequently updating fresh surfaces of CaCO. The CaCO could completely dissolve in the system for the removal of Pb on the same chemical molar equivalent. The removal rate reached simply over 99% with the aid of ball milling, based on the precipitations in the forms of lead carbonate (PbCO) from soluble nitrate and basic lead carbonate (Pb(CO)(OH)) from the hardly soluble sulfate occurring in a very wide concentration range. The process offered a new path for the treatment of abandoned lead paste based on the conversion of PbSO to PbCO or Pb(CO)(OH) as well as recycling of lead resources from multi-metal coexisting lead-containing waste solutions. These (basic) carbonates precipitates may be used as secondary resources, while achieving environmental purification.