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

Abstract

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.