Tellurium preparation - zone smelting process

Tellurium contains a variety of impurities. When the molten tellurium cools and solidifies, the distribution of impurities in the melt differs from that in the solidified crystal.

Zone melting raw materials are mainly 5 mol· l-1 Te. They are obtained from zone melting distillation.Zone melting equipment for high cleanliness of the charging part and reducing atmosphere system two parts. The product was melted in the atmosphere of pure H2, and its middle section, i.e., 7. 5 mol· l-1 product, was sampled and analyzed.The distribution of impurity concentration along the spindle length can be obtained by the following equation:

CPCO = 1 - (1 - k) e - kxPL (18)

Wherein, K = CS, which Cs is the impurity concentration in the solid phase; PCl is the distribution coefficient; Cl is the impurity concentration in the liquid phase; CO is the average impurity concentration; L is the width of the melting zone, and x is the distance between the beginning end and the solidification interface.

Technology practice zone melting molten zone is worthy of attention in reflux phenomenon, within the scope of boat tail length of a third have varying degrees of molten zone backflow, this phenomenon reduces the purification efficiency, the reason is the zone melting ingot on the following, cooling speed has considerable differences, become warped on materials ingot bending, and feeding ingot caused by uneven shrinkage of up and down.Here, take necessary measures to prevent reflux can improve the purification effect.

In addition, theoretically the width of melt zone, the moving speed and the state of melt stirring also affect the purification effect of melt zone, and the fluctuation of melt zone directly affects the separation effect, especially at a slow speed.Therefore, in order to keep the melting zone stable, accurate constant temperature and stable H2 flow rate are also essential.

Product recommendation : Tellurium

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