The thermal behaviour of divalent and higher valent metal soaps: a review

Preparation of lead carbonate from spent lead paste via chemical conversion

The influence of various experimental conditions such as sample weight, atmosphere and heating rate on the decomposition of NH4VO3, CaCO3 and V2O5 has been investigated. Results obtained clearly indicate that the course of the reactions and — in turn — the kinetic parameters, are not intrinsic to the particular compound and that they characterize rather the combination of experimental conditions and investigated compound. Such a situation makes it almost impossible to choose ‘standard conditions’ for the calculation of kinetic parameters, because under different circumstances quite different reaction-pathways can occur.

Somewhere between fiction and reality

An account of conventional dynamic thermal analysis (TA) with respect to uncertainties, failures, successes, and limitations as applied to solid-state (s-s) processes is discussed. A review of some controversial aspects of TA is presented. The scope is to discuss in three parts the adequate understanding of TA and to open a controversy about the dynamic methods and about the necessity of stimulating a consensus between scientists for a better TA. © 2001 John Wiley & Sons, Inc. Int J Chem Kinet 33: 343–353, 2001

The kinetics of solid‐state reactions toward consensus—Part I: Uncertainties, failures, and successes of conventional methods

Lead sulfate, lead dioxide and lead oxide are the main components of lead paste in a spent lead-acid battery. In addition, there are a few impurities in spent lead paste, which have great influence on the performance of the new battery; therefore, it is necessary to remove them. In this study, a novel approach with low temperature burning and hydrometallurgical processing with NH4AC is developed to recover lead from spent lead paste. First, some of the impurities are converted to metal oxides by the calcination of spent lead paste at low temperature. Second, the metal oxides are transformed into soluble sulphates by the reaction between the calcination products and dilute H2SO4 and H2O2 (5.0%). Then, the solids are separated from the solution by filtration; the solids are mainly PbSO4, BaSO4 and CaSO4. NH4AC is used as the leaching solution for PbSO4, and CO2 is introduced to obtain pure PbCO3. Under the optimized leaching conditions (leaching temperature at 40 °C for 20 min, 10.0 wt% NH4AC), the lead recovery ratio is about 99.9%. The calcination product of lead carbonate is PbO, and high-purity lead oxide is obtained. The initial discharge capacity of high-purity lead oxide is about 158 mA h g−1, and the capacity loss is less than 2% after 80 cycles.

Preparation of high-purity lead oxide from spent lead paste by low temperature burning and hydrometallurgical processing with ammonium acetate solution

Results are given on the kinetics and mechanism of the processes in the thermal decomposition of lead carbonate with the application of TG and DTA experimental investigation methods.

Ž. D. Živković

Papers

Kinetics and mechanism of thermal decomposition of lead carbonate