Translocation and mobility of thallium from zinc–lead ores

• Thallium in the ore oxidizable fraction is the major source of thallium dispersion.
• Oxidizable fraction is significantly enriched with thallium in flotation concentrates.
• Flotation causes high enrichment of bottom sediment oxidizable fraction in thallium.
• In typical soil the majority of thallium is entrapped in the residual parent matter.
• The water soluble thallium depends on the labile thallium content.

Thallium is a toxic, non-essential element. Zinc–lead ores are a known source of thallium pollution. The aim of this paper was to investigate the translocation of thallium from zinc–lead ores from the Cracow–Silesia Upland due to ore flotation processing and natural processes and the element's mobility in these samples as determined by sequential extraction in accordance with a modified BCR procedure. The oxidizable fraction of zinc–lead ores is the major source of thallium dispersion in the environment. During flotation, the galena and blende concentrates are significantly enriched with thallium, which is mainly located in the oxidizable and residual fractions. A side effect of flotation is a high concentration of thallium in the oxidizable fraction of rivulet bottom sediments. Soil formed above ore-bearing dolomites has the major part of its thallium in the oxidizable and reducible fractions. Soil formed above normal dolomites contains only 15% of the labile thallium (contained in the four fractions). This strongly supports the thesis that in typical soil the majority of the thallium is entrapped in the residual fraction. Water-soluble thallium is dependent on the labile thallium content.

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