KINETICS OF DISSOLUTION OF LEAD SULFATE FROM WASTE BATTERY SCRAP BY AQUEOUS TRIETHANOLAMINE SOLUTION

The rates of dissolution of lead sulphate from waste battery scrap in the form of flat surfaces by aqueous triethanolamine (TEA) solution have been measured under various experimental conditions. Temperature dependence data indicate that the dissolution process is diffusion-controlled (Ea = ∼10 kJ mol-1) above 45°C and below this temperature, the process appears partially chemically controlled (Ea = ∼27 kJ mol-1). In the lower temperature region under investigation, the chemical reaction which slows the dissolution is: PbSO4(s)+TEA(a,i)→Pb(TEA)2+ SO2-4(a,i) The rate constant, k, is 0.55 g s-1 m-2 mol-0.75 at 20°C with agitation speed of 1600 min-1. The rate is found to be 0.4th power dependent on stirring speed, which definitely indicates that the diffusion of TEA to and product species from the reaction site control the rate. The particle size of scrap powder used in making the pellets has little effect on the initial dissolution rate: 50 μm particles should be used to obtain uniform rates. © 1990.