Reclamation of Process Water and Silicon Fines
Shaping of silicon ingots prior to wafering comprises several cutting and grinding operations.
Large quantities of water must be used to cool tools and silicon surfaces, to act as a lubricant and to remove the resultant silicon fines. The spent process water leaves the tools highly contaminated by silicon particles.
The heart of such a reclaim system (see diagram below) is a dynamic membrane filtration (MF) unit combined with physico-chemical treatment of the concentrated silicon.
The systems clarify the contaminated process water. Typically 90 to 95 % of the contaminated process water is perfectly clarified ready for re-use. The remaining concentrate may be discharged, mixed with other wastewater streams, or subjected to additional treatment to meet discharge regulations or to de-water the silicon debris. Other options are available on request.