Reducing waste and increasing the yield

Elkem is finding new ways to reuse materials that previously have been disposed of and will terminate the use of landfills. The reuse of production waste from silicon and ferrosilicon smelters will increase the total yield and improve the environmental footprint of these activities. We also believe that this will result in economic benefits in the long term.

During different phases of the production process substantial quantities of raw materials and intermediate products must be removed and captured before the final product can be shipped to the customer. Traditionally, much of this has ended up in landfills as reuse has not been feasible either because of material characteristics or cost. Some has also been sold for a low price to customers who have managed to use it in their processes.

With our zero waste philosophy and long term goal of terminating landfills this is no longer acceptable and a number of initiatives have been taken, both to reduce the generation of waste throughout the production process and to reuse any waste that is generated.

Raw materials

One of the most exciting examples of improved reuse is through briquetting. During transportation and processing raw materials like quartz and coal are crushed creating a substantial amount of fine materials that cannot be used in the process even though they still contain valuable elements needed in the production. New methods to make solid briquettes from the fines have made it possible to feed the material back into the furnaces and increase the yield. The briquettes are strong enough to tolerate handling and transport and do not crack or break down when fed into the furnace making what was once seen as waste into good quality raw materials. The use of quartz fines in this manner reduces the import of quartz by 10,000-12,000 mt per year, which has led to considerable savings.

Off-grade microsilica

Another large source of waste has been off-grade microsilica particles captured in the filter process. Off-gas from silicon and ferrosilicon smelting furnaces is cleaned in large filters before emission to air, giving a valuable by-product called microsilica. During the process, heavier particles are removed using radiclones. Traditionally these particles have been considered worthless even though they contain valuable silicon, carbon and iron units which could be used as raw materials. By turning these into briquettes they can also be used as input when charging the furnaces. Waste is eliminated and yield is increased.

Using these methods some of Elkem’s plants are showing tremendous improvement with shares of waste to landfill reduced from 12% to about 5% and increased production yield for quartz about 5-6%.

Further development

A number of plants, including Elkem Iceland and Elkem Bremanger, are continuously working on new projects to reduce the generation of fines in their production, reuse fines in the process by briquetting or other methods, or to create higher value products from material that was once seen as low value or waste.

One example of creating higher value products from waste is cooperation with Silingen in Poland. In November 2016 Elkem and Silingen signed an exclusive co-operation agreement on product development, production, sales and marketing of FeSi Briquettes to the steel industry. For years, Silingen has been developing and producing high quality FeSi briquettes, mainly using raw materials from Elkem. With the cooperation they will be able to produce up to 18,000 mt per annum.

Elkem will be responsible for the supply of raw materials, as well as sales and marketing of the FeSi briquettes under the brand name BriqSil TM. Product development will be a joint effort between Elkem, Silingen and Elkem’s customers.