Patent ID: 9120674
Filing Date: 2015-09-01
Classification: B08B,C01B,G05D

Abstract:
1. A process for cleaning polycrystalline silicon chunks in an acidic cleaning bath, wherein the cleaning bath is part of an acid circuit in which acid is circulated, wherein the ratio of the amount of acid circulated in liters to the mass of polysilicon chucks present in the cleaning bath in kilograms is greater than ten, wherein the cleaning comprises several cleaning cycles, and wherein an amount of acid consumed per cleaning cycle by a given size class of silicon chunks is recorded as a parameter in a computer-controlled dosage system, said process comprising: adding up with an integrator of the computer-controlled dosage system the particular amount of acid consumed in each of the cleaning cycles to give a current total consumption of acid in the cleaning bath, and on attainment of a total consumption of acid in the cleaning bath that equals a predetermined value recorded in the computer-controlled dosage system, dosing a dosage of unconsumed acid into the cleaning bath from a reservoir vessel of the dosage system, wherein the dosage of unconsumed acid is a dosage that the dosage system can dose within an accuracy of ±10%, and wherein the predetermined value ranges from 5 to 30 liters.