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Related: About this forumAtmospheric Carbon Capture Performance of Legacy Iron and Steel Waste
The paper I will discuss in this post has the same title as this post. It can be found here: Atmospheric Carbon Capture Performance of Legacy Iron and Steel Waste Pullen et al, Environ. Sci. Technol. 2019 53 16 9502-9511)
It is, happily, open sourced. Anyone can read it.
All of the world's steel is made using coke, and all the world's coke, in turn, is made from coal. This is true of steel in buildings, in cars, bridges, and yes, that much hyped form of so called "renewable energy," wind turbine posts.
It's why it's appropriate to put the word "renewable" in quotations, as I almost always do.
If one travels to Bethlehem, PA, one can tour the abandoned steel plant from the historical Bethlehem Steel. It's worthwhile if one is interested in Engineering. Bethlehem Steel collapsed financially in 1995, after producing much of the steel for World War II ships, the Chrysler Building, the Golden Gate Bridge, etc. The town has done a credible job making the abandoned plant into an interesting tourist attraction, featuring among other things, a wonderful summer concert series in front of the hulking massive retorts.
Outside of town are the slag heaps. They are huge. I often wonder if they're toxic, but to my knowledge, they've not been tested.
It appears that some of the carbon dioxide associated with making steel can be sequestered using the slag at least according to this paper.
I won't spend a lot of time excerpting the paper, since it's open to anyone interested, but put in a few teasers:
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World steel output exceeded 1600 Mt in 2017.(20) In the EU, steel production released ?182 Mt of CO2(21) of greenhouse gases,(12,22) which equated to 45% of the EUs total emissions. However, it is estimated that 470610 Mt of slag was concurrently produced, which could negate some of these CO2 emissions.(23?25) Due to the reactive nature of some slag phases, e.g., larnite,(12) mineral CO2 sequestration is more rapid in slags than in natural silicates, e.g., forsterite (Mg2SiO4); thus, their utilization may incur lower energy consumption and costs.(26)
The authors note that slag apparently naturally only captures about 3% of the carbon it could capture, and propose processes for slag treatment that can raise that figure to values closer to the theoretical values.
In general, I do not favor sequestration because of its high energy intensity and its lack of a return on value, but have written extensively here and elsewhere about carbon capture and utilization.
In any case, it's an interesting little paper, and offers, if nothing else, some insight into the composition of slags.
If interested, enjoy it.