Method for cleaning metallurgical silicon material

Abstract

The invention relates to a method for cleaning a metallurgical silicon material, which comprises the following steps: crushing a metal silicon material to below 3 centimeters; preparing acid-washing impurity removing solution, and preparing mixed acid by using hydrofluoric acid and nitric acid in a ratio of 1:12-20; soaking the crushed silicon material into the mixed acid, and stirring and cleaning the silicon material for certain time; fishing out the cleaned silicon material, cleaning the silicon material by secondary purified water, and continually turning over the silicon material; and ultrasonically cleaning the silicon material by third-grade purified water, fishing out the cleaned silicon material when the pH is equal to 7, and drying the silicon material. When the silicon material contains impurities, the electrochemical potential energy and the surface activity in an area are changed, the impurities are enriched, the reaction electromotive force of the impurities is large, the reaction rate with the acid is high, then the metal silicon material is subjected to impurity removal to a certain degree by using the principle, and the best selective corrosion effect is realized by allocating the acid matching ratio, concentration and reaction time so as to remove more impurities, realize the selective corrosion effect and meet the usage requirements of solar cells on the silicon material.

Description

technical field [0001] The invention belongs to the field of silicon material cleaning, in particular to a metallurgical-grade silicon material cleaning method capable of removing part of the enriched impurities during material washing before metallurgical-grade silicon material impurities are put into a furnace. Background technique [0002] Polysilicon is mainly produced by two methods: chemical purification and physical purification. Among them, the chemical purification methods mainly include the Siemens method (vapor phase precipitation reaction method), silane thermal decomposition method, and fluidized bed method; the physical purification methods mainly include the zone melting purification method (FZ ), Czochralski single crystal method (CZ), directional solidification polysilicon ingot method (casting method) and so on. Currently the most mature polysilicon purification process is the Siemens method, which can achieve a silicon purity of 99.9999999% (9N), but this ...

AI Technical Summary

Problems solved by technology

[0004] At present, the purity of metallurgical silicon in the industry can only reach the level of 5N, and the content of other metal impurities except phosphorus and boron is still relatively high, so there are still many problems in actual use.