U. S. Steel Košice, s.r.o. (USSK) is an integrated steel producer located in Eastern Slovakia, with production capacity of 4.5 million tons of steel per year.
Steel has a fundamental place in the circular economy thanks to its inherent properties. Steel as a material is 100% recyclable, without loss of quality when properly processed. Moreover, it can be separated from waste streams very easily and economically thanks to its magnetic nature. Furthermore, every steel manufacturing plant is also a recycling facility as steel scrap is a natural part of the production process for new steel. As a result, there is no need to invest in new recycling plants or extra logistics which even further reduces the CO2-emissions and energy usage. On top of it, the steel-making process results in useful by-products and residues, such as process or waste gasses and air-cooled blast-furnace (but also steel shop) slags, both of which perfectly substitute for natural resources needed in other sectors, thus greatly contributing to resource efficiency.
- The gases unavoidably generated during the steel-making process in the blast furnaces or the coking batteries (Blast Furnace Gas, Basic Oxygen Furnace gas, coke oven gas) have been utilised for many years (transformed into electricity with as little flaring losses as possible) as secondary energy source and are the dominant energy source for many European facilities.
- Air-cooled blast-furnace slag, the by-product of the smelting process when the desired metal has been separated (smelted) from its raw ore, is used to substitute for clinker in cement production and in road construction, replacing the use of natural stone and thus avoiding all the environmental and energy impact and costs related to stone mining.
- Chemical compounds: sulphuric acid, sulphur, ammonium sulphate, benzene toluene xylene, tar, emulsions, and many others are valuable raw materials for the chemicals industry.
Utilisation of by-products and residues of the steelmaking process contributes to reduction of CO2 emissions, reduces the need for landfill and, at the same, substitutes for and subsequently saves other natural resources.
- USSK covers around 60% of its energy needs by generating its own electricity from the process (waste) gases – up to 900 GWh/year. The high-efficient power generation from own sources, namely the by-products of the steel-making, saves large amounts of conventional fuels that would have been otherwise needed to supply the plant with electricity. Using these gases as engine fuel thus reduces industrial CO2 emissions (contributing towards greenhouse gas reduction) and saves natural energy sources. Very importantly, it also provides an alternative disposal of a problem gas while simultaneously harnessing it as an energy source.
- Air-cooled blast-furnace slag is used as an alternative to natural rocks, such as limestone or granite, thus saving the energy that would have been required to mine natural aggregates, but also eliminating the negative impacts associated with mining (such as effects on biodiversity or disruption of the landscape), as the slag is already in place from the steel-making process. The annual volume of blast-furnace slag produced at USSK exceeds 1 million ton. Roughly 65% of such slag is cooled by water stream, granulated and then as such used for cement production (substitute for clinker) or construction purposes. Since 2012, the granulated slag from USSK has been utilized in building parking spaces as well as in construction of secondary and service roads (with the exception of motorways). The slag helped local urban and municipal governments to not only save the environment, but also considerable financial sources. In 2012 for instance, USSK delivered to Košice municipalities and urban areas more than 61,600 tons of the material, while in 2013 this amount exceeded 110,000 tons.
Although the properties of steel have a great potential within the circular economy, there are issues that need to be addressed.
- The process gases are used to generate electricity and to heat the plant itself. However, the legislators in Slovakia offer little incentive to use that energy. This is due to the fact that the same fees in fact apply to this self-generated energy as to the energy purchased from outside. Some sort of mechanism in the legislation that enables by-products to be reused is needed, so that the framework is advantageous for companies.
- The usage of air-cooled blast-furnace slag constitutes another barrier. Slovak authorities responsible for road construction have, for long time, been reluctant to accept this material as a relevant substitute for natural stone (though used all around Europe for decades) in highway construction. While until very recently, at European level 28% of blast furnace slag has been utilised in road construction, Slovakia was scraping only 1%. The situation started to improve over the past two years, with blast furnace slag being finally officially recognised as suitable material for motorway roads constructions (and not only for access roads) in November 2016.
- Steel industry faces challenges not only on national level, but also in the wider European context. The EU legal framework for product policy must recognised the concept of the ‘permanent’ material, providing the right incentives to foster their proper use. Industrially co-generated ferrous slags and process gasses have a range of economically viable and sustainable end uses and therefore, an EU legal framework should be established to grant ‘by-product’ status to these materials.
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