Plasma melting

Electrodes (W-Th02, W-Cu) and nozzles in plasma guns (W-Th02). The guns are used in plasma melting, arc cutting, and plasma spraying. 

Fiedler, H. et al. Results of plasma melting of steel, Fith Internat. Symp. Electroslag Remelting and Other Special Melting Processes Pittsburg, 1974... 

Japan. With this plant concentration in the exhaust gas is very low. Ash is treated by a plasma melting technique to generate no significant amount of dioxins. Furthermore the slag shows leaching values of heavy metals well below the legal limits for landfill. 

The concentration of dioxins in the slag is greatly reduced compared with the dioxins concentration in the fly ash. In a typical case more than 98% of dioxins are decomposed by plasma melting. In terms of TEQ (Toxic Equivalent Quantity), the dioxins concentration is only 0.01 ng (Table 2. ). 

Figure 2. Flow diagram of plasma melting process...

When plasma melting is applied, the plasma arc can cause the dissociation and recombination of oxygen and nitrogen thus forming NO. To avoid this, town gas is injected into at the slag hole. The effects of this operation are a) the volume of the exhaust gas is reduced and b) the temperature of the tapping hole gas increases. By this... 

Y. Higashi, T. Suzuki, Y.Shimizu, M.Yamada,. (1996) Plasma Melting Process for Incineration Ash of Municipal Solid Waste, Haikibutsugakkai Ronbunshu 7 193-201. 

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