Development of a Technology for Silicon Production by Recycling Wasted Optical Fiber

A process for the recycling of wasted optical fiber is proposed in this work. By reducing optical fiber, which consists of highly purified silica with a plastic coating, high-purity silicon is obtained. For the preliminary approach for this purpose, the reduction of the silica inside the optical fiber into silicon was carried out using an arc-plasma furnace. As a result, silicon was formed without the addition of carbon as a reducing agent. However, because the coating material was thermally decomposed and gasified in the early stage of the reaction, the quantity of carbonaceous compounds present as the reductant was deficient, resulting in the formation of silicon carbide or silicon monoxide as byproducts. Further addition of carbon showed no significant effect on the yield of silicon but increased the amount of silicon carbide. In contrast, the silicon carbide was found to improve the yield of silicon when it was recycled back into the reactant medium with the unreacted optical fiber.