The chlorosilane challenge

Companies in the solar industry that favor backward integration for using chlorosilanes to purify silicon can follow two different strategies. They can work with Evonik Industries, the only global chlorosilane producer that offers such partnerships. Or they can opt to plan, build, commission and operate their own chlorosilane plant.

 To make this decision, we recommend that companies critically review their own expertise and that of their service providers, if applicable, in the four phases of the project.






Companies that wish to operate their own chlorosilane plant should:

Phase 1 / Engineering and Construction
• …have significant experience in chlorosilane chemistry, at least in the construction of chemical plants for hazardous materials.
• …hire experienced service providers, who can prove that they have managed projects to a successful production start.
• …make contact with local licensing and control authorities early on, in order to identify potential hazards and be able to work relevant risk-reduction measures directly into the engineering process.
• …take suitable measures to enable appropriate recycling or disposal of secondary flows.
• …select specialist companies for the engineering and construction phase that have suitable know-how in the area of chemicals / hazardous materials and already have a verifiable record of building chlorosilane plants.

Phase 2 / Commissioning
• ...have suitable quantities of chlorosilanes for commissioning the plant .
• …ensure that well-trained professionals will be in charge of commissioning the plant.

Phase 3 / Operating a Chlorosilane Plant
• …begin the recruiting and training process for plant personnel as early as the engineering and construction phase.
• …prepare risk management plans to buffer production problems.

In the conception and production of high-efficiency plants for solar energy, the purification of metallurgical silicon to obtain solar silicon (solar grade) by the chlorosilane route is a particularly important step: the process is not physical/electrotechnical but physico-chemical. It is also risky and hard to control. 

Chlorosilanes are hazardous materials that are corrosive, sometimes flammable (only TCS, DCS, monosilane, not STC), and sometimes toxic. This creates special challenges for the operation of a chlorosilane plant, but it also creates the kind of challenges for coordination processes with licensing and auditing authorities that only experienced chemical companies know and manage.

This is why it makes sense for Evonik to offer existing and future customers help and advice, backed by more than 40 years of chlorosilane know-how.
Direct supply of various chlorosilanes in a wide variety of containers is not the only option we offer our customers. Under the Siridion® trademark, Evonik is also committed to direct cooperation in highly promising projects worldwide. As part of its “fence-to-fence” concept, Evonik plans, builds and operates a chlorosilane plant at the customer's site. This way, Evonik not only reduces the amount of the customer's investment but guarantees that this demanding process is in the hands of experts with more than 40 years of experience.