Making zero emissions steel and cement from a single process

Article by Adam Duckett

Steel recycling furnaces could also recycle waste concrete

Cement production: responsible for 8% of global emissions

WHAT if it were possible to make cement as a byproduct of recycling steel – and power production with green energy? This is the focus of a new two-year project involving researchers and industry from across the UK who are working to prove that two materials which are fundamental to society can be manufactured in a combined process that could help cut the huge volumes of emissions normally produced.

Cement is a staple of modern life. It’s used to make our homes, cities, and the infrastructure that connects them. Society uses so much that it’s our second-most consumed product after potable water. And the emissions it produces are huge, making up an estimated 8% of global output. Decarbonising cement manufacture is particularly challenging because CO2 is produced by burning fuels to heat the high-temperature kilns that are used to manufacture cement, and the chemical reactions involved in production naturally emit CO2 as well. To achieve climate targets and reach net zero by 2050, greener methods of producing high-volume materials like cement and steel will be crucial. Efforts are underway to capture the emissions from cement plants and store them underground and to embed the emissions within pre-cast blocks.

But engineers at the University of Cambridge have hit upon a different approach after they realised that the lime flux used in electric arc furnaces to recycle steel has almost the same chemical composition as the old waste cement paste that is produced when used concrete is crushed and the sand and aggregate removed. The result could be a process that converts construction and demolition waste into recycled cement using the furnaces that recycle scrap steel.

A change of flux

This article is adapted from an earlier online version.

Article by Adam Duckett

Editor, The Chemical Engineer

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