SILICON RECOVERY SYSTEM AND SILICON RECOVERY METHOD

摘要

PROBLEM TO BE SOLVED: To recover a silicon sludge having a high content of pure silicon.

SOLUTION: A silicon recovery system is structured by using a resin-made or stainless steel pipe to circulate waste water accompanying polishing and/or grinding of a crystal silicon, and disposing a sludge adsorption apparatus to adsorb a silicon sludge to a membrane element immersed in the waste water in a storage tank to store the circulated waste water, and a sludge drying apparatus to dry the adsorbed silicon sludge to obtain dried silicon sludge, wherein the amount of the waste water per unit time circulated in the pipe and the amount of waste water per unit time treated in the sludge adsorption apparatus are determined so that the residence time in which the silicon stays in the state of being contacted with water is made equal to or less than an upper-limit time calculated based on an oxidation coefficient indicating the time change rate of the oxygen concentration in the silicon in such a state and a target value of the oxygen concentration in the silicon recovered.

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