Method for prolonging service life of graphite crucible in medium smelting

Abstract

The invention belongs to the field of medium smelting technology, and particularly relates to a method for prolonging the service life of a graphite crucible in medium smelting. The graphite crucible is placed in a furnace body; and an induction coil is mounted in the graphite crucible. The method comprises the following steps of: (1) firstly fixing a graphite protection ring at the upper edge of the graphite crucible, and then adding industrial silicon into the graphite crucible; (2) starting the induction coil, heating to melt the industrial silicon into silicon liquid, and erecting a graphite column on the central shaft of the graphite crucible so that the liquid surface of the silicon liquid rises; (3) continuously adding industrial silicon into the graphite crucible, and controlling to increase the temperature of the induction coil so that the liquid surface of the molten silicon liquid is higher than the upper edge of the graphite crucible wall and lower than the upper edge of the graphite protection ring; and adding a slag former while keeping the surface of the slag former lower than the upper edge of the graphite protection ring, and then smelting; and (4) after smelting, performing a reaction between the silicon liquid and the graphite crucible to obtain a silicon carbide coating, then taking out the graphite column and the graphite protection ring, reducing temperature, and pouring out the silicon liquid.

Description

technical field [0001] The invention belongs to the technical field of medium smelting, and in particular relates to a method for increasing the service life of a graphite crucible in medium smelting. Background technique [0002] In a society where energy is scarce and low-carbon environmental protection is advocated, solar energy, as an environmentally friendly new energy, has great application value. Solar cells can convert solar energy into electrical energy, and solar-grade polysilicon materials are important raw materials for solar cells. Therefore, the preparation technology of solar-grade polysilicon materials is particularly important. At present, the main technical routes for preparing solar-grade polysilicon materials worldwide include: improved Siemens method, silane method, and metallurgical method. The principle of the improved Siemens method is to use high-purity hydrogen to reduce high-purity trichlorosilane on a high-purity silicon core at a temperature of ...

AI Technical Summary

Problems solved by technology

The traditional process cannot solve the problem of short service life of the graphite crucible, and the frequent replacement of the crucible also reduces the efficiency of the process

[0004] At the same time, the overall cost of the crucible made of silicon carbide material is too high, which is not conducive to industrial production

Images