Accelerated desulphurization of waste lead battery paste in a high-gravity rotating packed bed

• Rotating packed bed (RPB) reactor is firstly used for the Pb-paste desulphurization.
• Fast and continuous desulphurization process of Pb-paste could be achieved in RPB.
• The desulphurization degree of Pb-paste could reach 99.7% within one second.
• The desulphurization time was shortened by at least 2 orders of magnitude.

Pb-paste as the major composition in waste lead acid battery has an important role in the process of lead recycling. However, low liquid-solid mass transfer rates in conventional reactors have a significant limitation for the industrial application of Pb-paste desulphurization using hydrometallurgical process. In this paper, a cost-effective mass-transfer intensified approach for Pb-paste desulphurization with Na2CO3 solution in a rotating packed bed (RPB) reactor was presented. The effects of various variables on the desulphurization degree of PbSO4 were firstly explored. The results indicated that the increases in rotating speed, Na2CO3 concentration and Na2CO3/PbSO4 molar ratio were beneficial to the process. Temperature and reactant flow rate had obvious effects on the desulphurization degree only at a low reactant concentration. Further, the desulphurization processes of the simulated Pb-pastes were comparatively investigated. It was found that the RPB reactor markedly intensified the process in a very short contact time (about 1 s), thereby achieving a continuous desulphurization process. Only one cycle liquid-solid contact could make the desulphurization degrees of PbSO4, anode powder and cathode powder reach 99.7%, 98.9% and 97.2%, respectively. Compared to a stirred tank reactor, the desulphurization time was greatly shortened by at least 2 orders of magnitude.