A kind of cleaning method of silicon waste gas absorption tower

Abstract

The invention provides a cleaning method of a silicon material waste gas absorption tower. The method comprises the following steps of draining alkaline absorbing liquid out of the waste gas absorption tower, and using water to circulate and flush the waste gas absorption tower for the first time; using 4.5wt% to 5.5wt% of nitric acid solution to circulate and clean the flushed waste gas absorption tower; using water to circulate and flush the waste gas absorption tower for the second time. The method has the advantages that the waste gas absorption tower is cleaned by the nitric acid solution with higher oxidizing property, and the capacity of dissolving and removing the impurities and dirt is greatly improved by the oxidability of nitric acid, so a filler in the waste gas absorption tower is completely cleaned, the utilization rate of the nitric acid is improved, the cleaning cycle is greatly prolonged, and the waste gas treatment and cleaning cost of the silicon material waste gas absorption tower is reduced.

Description

technical field [0001] The invention relates to the technical field of solar cells, in particular to a cleaning method for a silicon waste gas absorption tower. Background technique [0002] In the production process of silicon materials in the photovoltaic industry, primary polysilicon or recycled silicon materials are used as raw materials, melted in a single crystal furnace, and then drawn into silicon materials for single crystal rods or polycrystalline ingots. The silicon material used to pull single crystal rods or polycrystalline ingots has high purity requirements, and the surface of silicon materials will be polluted during processing, transportation and storage, so the surface of silicon materials must be cleaned before use. [0003] At present, the mixed acid solution of hydrofluoric acid and nitric acid is generally used to clean the impurities on the surface of the silicon material. During the cleaning process, the metal impurities and oxides on the surface of t...

AI Technical Summary

Problems solved by technology

The above-mentioned salt compounds enter the waste gas tower with the reaction gas and volatilized gas for lye absorption treatment, and the solid substances such as sodium fluorosilicate, sodium silicate and sodium sulfide produced during the absorption process will slowly deposit and adhere to the filler, The nozzle and the inner wall of the pipe greatly affect the absorption effect of the exhaust gas tower, so the exhaust gas tower needs to be cleaned regularly

[0004] The traditional process is to dilute industrial-grade hydrochloric acid with a concentration of 37wt% to 6wt%, and then circulate the diluted hydrochloric acid in the exhaust gas tower to achieve the purpose of removing impurities and dirt, but the cleaning results show that the effect of hydrochloric acid cleaning the exhaust gas tower is relatively low Poor, the cleaning cycle is short, and nitrogen dioxide yellow smoke is easy to float out during the cleaning process, and the environmental protection is poor