silicon for the chemical and solar industry XIII

Silicon for the Chemical and Solar Industry XIII

Kristiansand, Norway, June 13 – 16, 2016

Recycling silicon from kerf and grinding processes -

the lost PV potential of silicon wastes

Dipl. Eng. Lou Parous

, Dr. Frank Weber

. Eng. Valdiney

Domingos de Oliveira

, Dr. Wolfgang Herbst

GmbH, Konstanz, Germany

GmbH - Von-Emmich-Str. 4, 78467 – Konstanz - Germany

Abstract

Every year the Photovoltaic sector expands as the cost benefits of solar are

disseminated worldwide with projections now for solar to reach the 100 GW per year

installed capacity in a very short time. With each GW of silicon based solar demand,

more and more metallurgical silicon is needed to support the polysilicon sector, which

is now on the verge of recovery after the last crisis in that industrial segment.

For all silicon based solar technologies, the processes required to provide polysilicon

for those technologies mandate the need for a ground metallurgical silicon powder as a

feedstock for this industrial segment. The silicones industry also requires the same

ground silicon, but the process of grinding silicon generates an off size material that

cannot be used by either industry. In fact, every year more than 100 000 tons of silicon

off spec waste is generated from this process that fall out of the value chain for which

they were originally produced.

Additionally, further down the process of making solar devices, the manufacturing

of solar wafers generates an additional more than 100 000 tons of silicon contaminated

with SiC from the FAS

and LAS

process steps that is not used to make solar energy.

The potential solar power from these wastes is forever lost and represents over 45 GW

annually given today’s PV market.

The authors are developing and planning a waste silicon recycling factory to convert

this waste from kerf and grinding processes back into the value chain as a feedstock for

polysilicon production, thereby reducing the lost potential of this waste and providing a

low cost feedstock for polysilicon producers. The authors are

currently developing a

factory project to capture the lost opportunity of waste silicon by combining proven

technology advancements in solid-liquid separation techniques with modern gas

atomization of silicon fines, resulting in chemically superior silicon with low impurities

and homogenous physical characteristics for polysilicon production and

Methylchorosilane production.

Fixed abrasive slurry

Loose abrasive slurry