Investigation of the evaporation kinetics of a lead-silver alloy and elementary substances under vacuum

A novel method for statistically analyzing the evaporation rate of metals is introduced. The variation in the masses of elemental metals and a lead-silver alloy over time is measured by a vacuum thermogravimetric furnace, and the evaporation rates of the metals are obtained through mathematical statistical analysis at temperatures of 1073–1573 K and ambient pressures of 3.5–500 Pa. The experimental results indicate that the logarithm of the evaporation rates of a lead-silver alloy and sample substance are linearly related to the reciprocal of the temperature at the 95% confidence level, which satisfies the dependent linear equation lgω=−CT+ω0. The evaporation rates of lead and silver at environmental pressure conform to the reciprocal of the exponential model, ω=A*exp−PB+ω0'. At an ambient pressure of 10 Pa and temperatures of 1073–1573 K, the evaporation rates of the lead-silver alloy with 10% silver and the sample substance approximately satisfy the following relationship: lgωPb-Ag=95.92%lgωPb+19.01%lgωAg. This work has obtained the basic evaporation kinetic parameters of the lead-silver system components, which provides basic theoretical guidance for the gasification and separation of a noble lead alloy to achieve the removal of impurity lead and enrichment of precious metals. •Mathematical statistical analysis methods are applied to the calculation of evaporation rate.•The kinetic model of evaporation rate varied by evaporation temperature is lgω=−CT+ω0.•The relationship between evaporation rate and ambient pressure is ω=A∗exp−PB+ω0'.•Theoretical guidance for vacuum distillation of precious lead is provided.