Transfer of chemical elements in vapor-gas streams at the dehydration of secondary sulfates

Abstract

The elemental composition of vapor-gas streams obtained during heating of secondary hydrous sulfates are presented. Samples of abundant sulfate intergrowth were collected at the Belovo waste heaps and heated at 60ºC in experiments to collect condensates of the releasing vapor-gas streams. A wide spectrum of major and trace elements was determined in the condensate. Chemical elements can be absorbed by the water vapor and migrate with this phase during the dehydration of hydrous sulfates. To determine the mechanisms of migration and the sources of elements in vapor-gas streams, a study of the features of certain hydrous sulphates (antlerite, goslarite, starkeyite, gunningite, siderotile, sideronatrite) by stepwise heating up to 60ºC was conducted. Alteration in the phase composition is controlled by powder X-ray diffractometry. It was determined, that antlerite and starkeite remain stable throughout the temperature range. The beginning of the separation of structural water in goslarite and siderotile occurs at 40°C. Goslarite and sideronatrite at 40°C lost water molecules and transformed to gunningite and Na-jarosite, correspondingly. Structure of siderotile was loosened. The modes of occurrence of the chemical elements in sulfates and pore solution determine the concentrations of elements in the condensates.