[Synthesis of high-concentration polyaluminum chloride and its aluminium species distribution and transformation]

Using solid CaO as basification agent, the high-concentration polyaluminum chloride (PAC) was prepared by feeding total alkali at a time. The characteristics of the reaction and the distribution and transformation of the aluminium species were also studied. The experimental results show that the distinctive hydration of CaO can contribute to the high-concentration PAC whose Al concentration (Al(T)) and basicity (B) can reach 2.1 mol/L and 2.1 respectively. There is an optimal B value in any concentration of PAC, at which the Al(b) content is the highest. The optimal B value and the highest Al(b) content drops with the increasing of Al(T). The predominant reaction is the formation of Al(b) if B is less than the optimal B value, and the formation of Al(c) if B is more than the optimal B value.