Description
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Thallium is one the poor metals that has a bright, silvery white, color in its natural solid state. It is a soft and malleable poor metal, and it is highly toxic. Thallium has an atomic weight of 204.3833, a melting point of 579°F, and a boiling point of 2683 °F. Some common uses of thallium include: as a component in photo cells, as a component in infrared optical materials, in the manufacture of certain types of glasses, and as a component in equipment used to detect gamma radiation.
Isolation
Thallium is not found freely in nature, and needs to be isolated from the compounds it occurs in. A number of isolation methods can be used.
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Due to the toxicity of thallium, the isolation procedures needed to extract it from the compounds it occurs in are not normally carried out on a small scale laboratory basis. Instead, thallium is extracted from certain sources on a commercial basis. While thallium occurs in clays, soils, and granites it is not isolated from these compounds as the procedures are too expensive. The most widely used isolation procedures for thallium commercial needs are from small amounts that are found in copper, lead, sulfide ores, and zinc.
The smelting process carried out on lead and zinc ores can be used to recover thallium. The smelting process is a form of chemical reduction that uses extractive metallurgy to isolate elements that occur in the same compounds from one another. Thallium can also be isolated as a byproduct of roasting pyrites for sulfuric acid recovery. Pure thallium must be handled with extreme caution due to its toxicity and cancer causing characteristics.