Influences of palladium ceramics on valuable metal losses to a PbO-SiO2-Sb2O3 based silver smelting slag.

Abstract: Silver and palladium can be found in the so called palladium-ceramics which comes from catalyst production. These valuable metals needs to be recovered from these wastes in order to further increase both the environmental and economic sustainability of our society. This material has also been suspected of causing some problems at Boliden’s smelter Rönnskär during the silver smelting. Unfortunately due to the nature of massive economics at work in precious metal production there has not been much published work around this subject. Therefore this works seeks to increase the understanding of how this waste affects the A-slag in the precious metal production at Rönnskär.   This work takes a look at how certain fluxes and temperatures affects the slag and metal phases, as well as how increasing the addition of the palladium-ceramic affects the melt. It does so by making screening tests with a basic setup of slag from the process, silver granules and additions of coke and sodium carbonate at different temperatures.   The results show that using a reducing environment by adding coke does increase the recovery of the precious metals. Increasing the temperature of the melt also shows an improvement in the recovery of the precious metals.  Furthermore the basis to an alternative way of using this material, consisting of smelting it together with silver and fluxing materials has been suggested in this work in order to eliminate the possible problems it causes in the current process.