Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Reducing Iron Oxide with Ammonia: A Sustainable Path to Green Steel

onlinelibrary.wiley.com

Post reply on HN
Print view View original

11–20 of 86 posts

Re: Reducing Iron Oxide with Ammonia: A Sustainable Path to Green Steel

#11

Post by adastra22 »

tonyarkles wrote: post #7
philipkglass wrote: post #6

Earlier quoted context omitted.

I would guess that even better than shipping ammonia or hydrogen to European steel plants would be to build new steel plants near the hydrogen producers, wherever they may be, and shipping iron ore there while shipping steel back out. Since iron ore and steel are much denser than either ammonia or hydrogen and do not need pressure vessels or chilling they can be shipped at lower speeds (save transport energy consumpt…

I'm asking this 100% from a place of curiosity because I don't know the answer. From iron ore to steel, how much waste is there? If the waste fraction is large, people might balk at the idea of either leaving that waste behind in the hydrogen-host country or burning fossil fuels to ship it around to have a carbon-free extraction process.

Anywhere you have water you have hydrogen.

Re: Reducing Iron Oxide with Ammonia: A Sustainable Path to Green Steel

#12

Post by frankus »

philipkglass wrote: post #6
PaulHoule wrote: post #4

Earlier quoted context omitted.

i think the question is how far you are shipping the hydrogen. If, say, people are making hydrogen in (say) the Middle East and shipping it to (say) Europe then the overhead of liquifying or compressing H2 is on the same order as converting to ammonia. In that paper they demonstrate that you can just use the ammonia directly to reduce iron and not have a separate system to convert it back. If you have a big wind powe…

I would guess that even better than shipping ammonia or hydrogen to European steel plants would be to build new steel plants near the hydrogen producers, wherever they may be, and shipping iron ore there while shipping steel back out. Since iron ore and steel are much denser than either ammonia or hydrogen and do not need pressure vessels or chilling they can be shipped at lower speeds (save transport energy consumpt…

Anhydrous ammonia’s volatility is on the order of that of propane/LPG (although a lot more hazardous to inhale), so the containment is easier than what the words “pressure vessel” might evoke.

Re: Reducing Iron Oxide with Ammonia: A Sustainable Path to Green Steel

#13

Post by thereisnospork »

azernik wrote: post #5
Robotbeat wrote: post #2

I don’t get this. We already use direct reduction using about half hydrogen, and that can be increased to over 90%. Producing ammonia via the Haber process means losing 40% or so of the energy (and potentially more as you convert it back), so why not just use hydrogen directly? Simply because moving hydrogen is harder than ammonia? I think it makes way more sense to just make and use the hydrogen on-site.

This isn't using ammonia to transport hydrogen; the nitrogen is what's reacting with the iron. And yes, ease of transportation and reactivity is a big motivator. From the abstract: "Ammonia is an annually 180 million ton traded chemical energy carrier, with established transcontinental logistics and low liquefaction costs. It can be synthesized with green hydrogen and release hydrogen again through the reduction reac…

>the nitrogen is what's reacting with the iron.

Only in a supplementary manner to form a nitride coating as rust proofing - the primary reducing agent is hydrogen, forming water.

relevant snippet:

>>The nitride formation is another key advantage of ADR, as nitriding improves the aqueous corrosion resistance of iron.[29] The nitride passivated the otherwise highly active reduced iron, offering a safety-critical benefit for handling and logistics. Otherwise, for the downstream processing of the reduced material, the porous sponge iron is prone to re-oxidation and strong exothermic reactions with oxygen or moisture due to its high surface-to-volume ratio (typically above 40 vol% porosity[4]). Thus, the sponge iron produced by HyDR must be compacted into hot briquetted iron to reduce the porosity for shipping and handling, which is not necessary with ADR.

Re: Reducing Iron Oxide with Ammonia: A Sustainable Path to Green Steel

#15

Post by to11mtm »

tonyarkles wrote: post #7
philipkglass wrote: post #6

Earlier quoted context omitted.

I would guess that even better than shipping ammonia or hydrogen to European steel plants would be to build new steel plants near the hydrogen producers, wherever they may be, and shipping iron ore there while shipping steel back out. Since iron ore and steel are much denser than either ammonia or hydrogen and do not need pressure vessels or chilling they can be shipped at lower speeds (save transport energy consumpt…

I'm asking this 100% from a place of curiosity because I don't know the answer. From iron ore to steel, how much waste is there? If the waste fraction is large, people might balk at the idea of either leaving that waste behind in the hydrogen-host country or burning fossil fuels to ship it around to have a carbon-free extraction process.

> From iron ore to steel, how much waste is there?

Depends on how we define 'waste' and at what part of the process.

When they start with the rock from the ground/pit, the rocks/etc are often crushed, running through some sort of slurry while basically separating the 'ore' out from silicates/etc that will be around them. I'm guessing this is already done close to the site, since transport cost could be fairly high even by past standards.

What you wind up Iron ores that are considered 'worth' mining, the actual Iron content is anywhere from ~48% to ~72%. They'll typically have Oxygen, Possibly also Carbon or hydrogen as the 'impurities'.

So, there's still a lot of potential waste in transporting all of that.

[0] - Also, that would theoretically be useful in filling the pit back up, one would hope. But not sure on that one.

Re: Reducing Iron Oxide with Ammonia: A Sustainable Path to Green Steel

#16

Post by to11mtm »

adastra22 wrote: post #11
tonyarkles wrote: post #7

Earlier quoted context omitted.

I'm asking this 100% from a place of curiosity because I don't know the answer. From iron ore to steel, how much waste is there? If the waste fraction is large, people might balk at the idea of either leaving that waste behind in the hydrogen-host country or burning fossil fuels to ship it around to have a carbon-free extraction process.

Anywhere you have water you have hydrogen.

Interestingly, the paper mentions that the reactions do produce (some) hydrogen, which could perhaps be recaptured.

However, a bigger concern upon a glance is that this process does produce NOx emissions...

Re: Reducing Iron Oxide with Ammonia: A Sustainable Path to Green Steel

#17

Post by photochemsyn »

PaulHoule wrote: post #4
Robotbeat wrote: post #2

I don’t get this. We already use direct reduction using about half hydrogen, and that can be increased to over 90%. Producing ammonia via the Haber process means losing 40% or so of the energy (and potentially more as you convert it back), so why not just use hydrogen directly? Simply because moving hydrogen is harder than ammonia? I think it makes way more sense to just make and use the hydrogen on-site.

i think the question is how far you are shipping the hydrogen. If, say, people are making hydrogen in (say) the Middle East and shipping it to (say) Europe then the overhead of liquifying or compressing H2 is on the same order as converting to ammonia. In that paper they demonstrate that you can just use the ammonia directly to reduce iron and not have a separate system to convert it back. If you have a big wind powe…

I think it's more rational to ship the hydrogen as methane, rather than ammonia. The energetics are comparable IIRC (Sabatier for methane, Haber-Bosch for ammonia, but it's more or less the same kind of high-pressure moderate-temp chemistry pipeline). Methane from CO2 + H2 vs. ammonia from N2 + H2, it's just that the latter technology has seen more research and investment.

Re: Reducing Iron Oxide with Ammonia: A Sustainable Path to Green Steel

#18

Post by boshomi »

Reduction of iron ore with carbon monoxid in closed loop:

• Decarbonisation of BF-BOF through thermochemical closed carbon looping.

• Demonstration of mass and energy flows of thermochemical BF-BOF system.

• 88% emissions reduction of UK steel industry through £720 million investment.

• Decarbonisation without retiring of existing BF-BOF, reducing stranded assets.

• After 5 years, £1.28 billion savings and total UK-wide emissions reduction of 2.9%.

“if the thermochemical closed reactors were exclusively powered by electricity, it would require 607 kWh/t liquid steel.”

»Cost effective decarbonisation of blast furnace – basic oxygen furnace steel production through thermochemical sector coupling« -- https://doi.org/10.1016/j.jclepro.2023.135963

Re: Reducing Iron Oxide with Ammonia: A Sustainable Path to Green Steel

#19

Post by londons_explore »

to11mtm wrote: post #16
adastra22 wrote: post #11

Earlier quoted context omitted.

Anywhere you have water you have hydrogen.

Interestingly, the paper mentions that the reactions do produce (some) hydrogen, which could perhaps be recaptured. However, a bigger concern upon a glance is that this process does produce NOx emissions...

NOx from big industrial processes tends not to be an issue. Catalytically reducing it to N2 and O2 is easy, and at the same time, you get out 'free' high grade heat, which there is usually some use for elsewhere in the plant.

Re: Reducing Iron Oxide with Ammonia: A Sustainable Path to Green Steel

#20

Post by ClumsyPilot »

philipkglass wrote: post #6
PaulHoule wrote: post #4

Earlier quoted context omitted.

i think the question is how far you are shipping the hydrogen. If, say, people are making hydrogen in (say) the Middle East and shipping it to (say) Europe then the overhead of liquifying or compressing H2 is on the same order as converting to ammonia. In that paper they demonstrate that you can just use the ammonia directly to reduce iron and not have a separate system to convert it back. If you have a big wind powe…

I would guess that even better than shipping ammonia or hydrogen to European steel plants would be to build new steel plants near the hydrogen producers, wherever they may be, and shipping iron ore there while shipping steel back out. Since iron ore and steel are much denser than either ammonia or hydrogen and do not need pressure vessels or chilling they can be shipped at lower speeds (save transport energy consumpt…

Exactly, I struggle to see any situation, barring mismanagement or disaster, where you should be shipping tankers full of hydrogen byproducts like ammonia and losing most of the energy in the process.

We are currently importing all the natural gas in Europe, and both the price and carbon footrpint are more than double of what pipeline delivered from Russia.

You could build a pipeline from the middle east to Europe for hydrogen. We are already building powerplants in Sahara to export energy to EU. But I do not see why you should ever need to.

Iron ore and Aluminium ore is literally everywhere. We could move all of primary metal refining close to equator for solar power. China is close enough to equator, and produces huge quantities of Iron. Australia could be producing iron, they have plenty of sun.

Or Europe could produce hydrogen in the summer and store for the winter to keep refineries running.

Post reply on HN