Frankly speaking, in recent years there are not many days in the Orava region to be optimist about or praise ourselves. However, shortly we will grab the fruits of several months of a hard work. OFZ, a.s. Istebné is to launch a brand-new production process which will bring traditional metallurgy to another level.
One of our electric arc furnaces (EAF) has been revamped and rebuilt for production of silicon metal - material to be found almost everywhere from microprocessors, through photovoltaic cells to alloys for automotive and aircraft industry. Simply speaking, in today`s economy, this material is used in the most progressive sectors with ever increasing demand. We strongly believe that this is the future for our company and the same time the future for maintaining employment in the Orava region for our workers.
The extensive investments targeted into renewable energy generation put pressure on still growing demand for material to be produced at OFZ, a.s. from March this year. Silicon very rarely occurs as the pure element but rather it is widely distributed in the various forms of oxides. That is the reason why silicon needs to be melted in electric arc furnaces and crystallizers to produce a pure form with extensive uses in photovoltaic, chemical, and processing industry. Its properties as an alloy with aluminium are also highly appreciated. Use of such materials in automotive and aircraft industry decreases the weight of final product while preserving its strength. High-purity silicon is widely used in electrical engineering for production of microprocessors - so the name of legendary Silicon Valley in California.
To avoid silicon carbide built-up, the furnace is equipped with rotation system and four tapping holes.
Silicon metal production is a big step forward in the metallurgical industry in Slovakia. With using modern technologies, our aim is to become a resource base for existing and new processing industry. The traditional markets had proved to be highly volatile; therefore, we decided to pursue a strategy of diversification. Product portfolio extension is to mitigate the negative impacts of swings in raw material costs and prices for our traditional products.
The demand is mainly for silicon with purity of 98.5 to 99 % and the remaining 1.0 to 1.5 % is comprised of impurities such as aluminium, calcium and iron. The content of impurities has to be minimized or completely removed through a process of refining. From the metallurgy point of view, silicon metal is simply ferro-silicon (FeSi) with a high content of silicon. The key point here is to minimize the content of iron since this element cannot be removed through refining. A number of adjustments were required to finally tune in the system and technology to highly specific chemical composition of this product.
For the production of silicon metal, a higher homogeneity of charge is needed. At the end of charging system, the system of weigh belt conveyors has been built which enables to prepare a homogenous mixture through a so-called "sandwich way". Moreover, the exhaust system has been enhanced and as mentioned above, refining of produced metal has been involved as a new step in production process. This technology has helped us to gather a rich experience in manufacturing the other type of products.