Refinery for the production of solar grade silicon and different products of high value added

Laburpena

Like other renewable energies, photovoltaic solar energy constitutes an inexhaustible resource in comparison to fossil resource. This contributes to a national and social energetic auto-supply with low environmental impact comparatively lower to traditional energy sources. In light of this, focus on the obtainment of products for the creation of solar panels becomes important. The obtention of solar-grade silicon is undoubtedly a process that calls for many inconveniences; mainly, the cost for its obtention on account of the need of high purity, the environmental impact this process represents, the setting up of the process, the health risk factors that existing components and conditions bring about and, worker’s occupational health. In the present work, there is a description (design) and assessment of various indexes of the novel obtainment process of solar-grade silicon. One that obtains different high added value products, is cost-effective, has a low environmental impact and is safe at once. For that matter, throughout the text there is a compendium of a series of works done in a sequenced fashion that give an account of its design, the assessment of different indexes (financial, environmental impact, security and occupational health), and the improvement of a high performance process (under the proposed ideal operative guidelines). In those works, there is a comparison between the novel process with existing ones to produce solar-grade silicon (meaning the Siemens process and the Union Carbide process) to have a real reference of the range of the proposed process. The first part, results showed similar cost-effective between the Hybrid Process (15.21 %) and the Union Carbide process (15.38%). Overall, the high demand for the product of interest -under the precondition of a safe process-, the Hybrid Process can be deemed as an option for an industrial execution. When the novel process is improved to obtain a higher efficiency under operative guidelines, an OPEX of 6.46 M$/y as a way of increasing the profit from that process. After the operative costs, the selling of solar-grade silicon and its by-products, the income is of 10 M$/y (with a competitive price for polycrystalline silicone of 8.93 $/kg., below the 11 $/kg. estimated commercial price). In conclusion, the proposed process is capable of meeting future demand in a cost-effective, environmentally friendly and safe way. Likewise, the results show that with the refinery that produces tetraethoxysilane and chlorosilanes in addition to the production of polysilicon, the proposed design reduces the cost for polycrystalline silicon to 6.86 $/kg, compared to a cost of polycrystalline silicon if the plant does not generate high value-added by-products, both below the commercial price.