Enhanced characterisation for the management of industrial steel processing by products: potential of sequential chemical extraction

Reuse and Recycling of By-Products in the Steel Sector: Recent Achievements Paving the Way to Circular Economy and Industrial Symbiosis in Europe

Over the last few decades, the European steel industry has focused its efforts on the improvement of by-product recovery and quality, based not only on existing technologies, but also on the development of innovative sustainable solutions. These activities have led the steel industry to save natural resources and to reduce its environmental impact, resulting in being closer to its “zero-waste” goal. In addition, the concept of Circular Economy has been recently strongly emphasised at a European level. The opportunity is perceived of improving the environmental sustainability of the steel production by saving primary raw materials and costs related to by-products and waste landfilling. The aim of this review paper was to analyse the most recent results on the reuse and recycling of by-products of the steelmaking cycles as well as on the exploitation of by-products from other activities outside the steel production cycle, such as alternative carbon sources (e.g., biomasses and plastics). The most relevant results are identified and a global vision of the state-of-the-art is extracted, in order to provide a comprehensive overview of the main outcomes achieved by the European steel industry and of the ongoing or potential synergies with other industrial sectors.

The Potential of Remedial Techniques for Hazard Reduction of Steel Process by Products: Impact on Steel Processing, Waste Management, the Environment and Risk to Human Health

The negative impact from industrial pollution of the environment is still a global occurrence, and as a consequence legislation and subsequent regulation is becoming increasingly stringent in response, in particular, to minimising potential impact on human health. These changes have generated growing pressures for the steel industry to innovate to meet new regulations driving a change to the approach to waste management across the industrial landscape, with increasing focus on the principles of a circular economy. With a knowledge of the compositional profiles of process by-products, we have assessed chemical cleaning to improve environmental performance and minimise disruption to manufacturing processes, demonstrating re-use and recycling capacity. We show that with a knowledge of phase composition, we are able to apply stabilisation methods that can either utilise waste streams directly or allow manipulation, making them suitable for re-use and/or inert disposal. We studied blast furnace slags and Portland cement mixes (50%/50% and 30%/70%) with a variety of other plant wastes (electrostatic precipitator dusts (ESP), blast furnace (BF) sludge and basic oxygen furnace (BOF) sludge) which resulted in up to 90% immobilisation of hazardous constituents. The addition of organic additives i.e., citric acid can liberate or immobilise problematic constituents; in the case of K, both outcomes occurred depending on the waste type; ESP dust BF sludge and BOF fine sludge. Pb and Zn however were liberated with a 50–80% and 50–60% residue reduction respectively, which generates possibilities for alternative uses of materials to reduce environmental and human health impact.