Effect of clay on coal-combustion fluorine pollution in Zhaotong

The fluorine content, emission rate of coal, clay, mixed coal and clay used by peasant households, and the relation between them and fluorine pollution in Zhaotong of Yunnan province have been studied by using an ion selective electrode (ISE) and solidoid balance methods. The results show that the fluorine emission rate, capacity of mixed coal and clay are higher than that of block coal; the clay as a binder for fine coal is one important source of fluorine pollution caused by coal-combustion in Zhaotong. When the fluorine content of the clay is about 640 mg/kg, it's fluorine emission amount is about 40-60 percent of all the fluorine emission amount generated by coal-combustion. Only using the block coal which fluorine content is about 50 mg/kg to dry corn, it also could result in the fluorine pollution to corn, and the fluorine content of the corn after dried is beyond the tolerance limits of fluorine in food. But the fluorine pollution to the corn caused by only using block coal to dry corn is less than that caused by using block coal, mixed coal and clay to dry corn.