Developing iron-rich cement clinker & understanding ferrite for the valorisation & upcycling of steel slags (FeRICH)

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The cement and steel sectors are foundational to the UK, are the largest manufacturing industries (by mass), and are essential to construct our infrastructure. Cement manufacture is intensive in resources, carbon, and energy, and needs radical transformation to achieve sustainability. The steel industry produces up to 1M tonnes of steel making by-products annually, and into the foreseeable future. These waste materials need to be managed properly to improve resource efficiency, and to avoid landfill and subsequent ecotoxicity. Although effective utilisation of steel slags is ~80%, a large portion is unutilised. Moreover, the majority of slag utilisation is for low-value products, e.g. aggregate, but their chemistry and mineralogy are variable, making their effects on material properties unpredictable, in the absence of further processing. Additionally, more than 190 Mt of legacy iron and steel slag are present across the country.The UK's cement industry is set to cut 4.2 MtCO2 emissions per year by 2050, about half of which is to be gained by resource efficiency in cement plants. Every year, the UK cement sector consumes ~12.5 Mt of natural raw materials, which can potentially be substituted with by-products that the steel sector produces. These materials contain the key elements that are essential to cement making, but they also have an unusually high amount of iron. FeRICH aims to replace the natural raw materials used in Portland cement making by valorising and upcycling iron-rich waste materials from the steel industry. This leads to cements containing an unprecedented level of [calcium] ferrites; however, our understanding of ferrite chemistry is still incomplete, and we need to establish what happens to this phase both during cement production and after use.These side streams also constitute other minor elements that are likely to alter the cement chemistry. Therefore, we need to develop the knowledge underpinning the interdependency between the role of minor elements in ferrite chemistry, what controls the reaction of ferrite with water over time alone or in mixture with other phases occurring in cement, and importantly, the long-term durability of ferrite-rich cement. Along with this, we also need to develop modelling tools to be able to predict the relationship between these factors - FeRICH relies on thermodynamics as a powerful technique here. We also recognise that ferrite-rich cements are ferromagnetic, and this property can add functional properties to cement (or subsequently to concrete) which may be exploited throughout the materials lifetime: form manufacturing to both their service life and end of life.FeRICH will develop and validate data-for-manufacturing of ferrite rich Portland cement. From reactions at high temperature in kilns to reaction with water at ambient temperatures, we will establish the best cement making conditions and materials compositions to achieve maximum process, energy and resource efficiency in kilns and cement performance upon reaction with water. For the first time, we will also examine the electromagnetic properties of ferrites related to cement, laying down the foundation for building intelligent systems in the future infrastructure. The findings and data developed in this project will be assimilated into tools that will accelerate the uptake of iron rich wastes in cement making. FeRICH will reduce the environmental burden of the cement industry and drive the steel industry towards zero-waste through implementation of the circular economy strategy. This will help alleviate the current crisis in the UK steel industry whose competitiveness in the global market is inhibited by a higher overhead costs than other countries. The results will allow for the use of other iron-rich materials for cement making, in the UK and worldwide.