The Migration And Release Of Thallium In The Exploitation Of Pyrite Containing Thallium

Thallium (Tl) is a severe toxicity and scattered heavy metals, and has very low concentration in the earth's crust (0.75mg/kg). Abundance of mineral resource containing Tl has been found in our country. Tl could be released into atmosphere, water and soil, and then enter into and accumulated in person and animals body through food chain, induce Tl chronic poisoning or endemic disease to human beings. With the rapid development of economy in our country, the demand for mineral resource will be gradually increase, the degree of exploitation will be increased simultaneity, and the environment crisis of Tl will be caused more and more serious. However, there has no much attention on the Tl pollution problems caused by the exploitation of mineral resource containing Tl in the international world and the mechanism of migration and release of Tl is still unclear now, and toxicity Tl has not been monitored as one pollutants by environmental protection bureau. So the systemic studies the mechanism of migration and release of Tl not only has important theoretic values, but also has magnitude instruct significance for prevent Tl pollution in the exploitation of mineral resource containing Tl.In this work, samples were collected from different pyrite ores, sulfur acid slag collected from different phase of sulfur acid production, soils profiles around the slag pile site and background soil. Tl concentrations and forms in samples were analyzed by ICP-MS and sequential extraction procedure. It indicate that (1) Tl forms changed after pyrite roasting and a lot of Tl released into gas phase, then let into waste gas, wastewater and slag, and will do harm to environment. So the key of controller Tl pollution was control Tl release to gas phase in sulfur acid production, to prevent Tl let into waste gas, wastewater and slag; (2) Thallium in slag has distinct release ability under natural leaching and was affected by its forms and some conditions (such as pH, temperature and components of slag); (3) The soil around the slag pile has been serious polluted by Tl in slag in the process of natural leaching. Thallium from different source has different geochemical behaviors in soils. Anthropogenic Tl has stronger mobility than natural Tl, so has high bioaviability and hazardless for environment. The various soil components have different ability to adsorbed Tl and mainly effected by soil pH. Thallium mobility will be enhanced with soil acidification.The sulfur acid slag has high annul production and piled in air, the Tl pollutant will be rapidly released into environment in the process of leaching. Moreover, thetranslation, piling again and using of slag will extend the range of contamination. The sulfur acid plant usually lies in the residential area, so ecology environment deteriorate by Tl pollutant will directly related with behalf of public health. So the area of Tl prevention and cure become one of a urgent environment problem.