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.
