[HN Gopher] Reducing Iron Oxide with Ammonia: A Sustainable Path...
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Reducing Iron Oxide with Ammonia: A Sustainable Path to Green Steel
Author : PaulHoule
Score : 67 points
Date : 2023-04-02 18:43 UTC (4 hours ago)
(HTM) web link (onlinelibrary.wiley.com)
(TXT) w3m dump (onlinelibrary.wiley.com)
| Robotbeat wrote:
| 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.
| azernik wrote:
| 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 reaction."
|
| Also: "The authors show that ammonia-based reduction of iron
| oxide proceeds through an autocatalytic reaction, is
| kinetically as effective as hydrogen-based direct reduction,
| yields the same metallization, and can be industrially realized
| with existing technologies."
| thereisnospork wrote:
| >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.
| algo_trader wrote:
| > Producing ammonia via the Haber process means losing 40% or
| so of the energy
|
| This seems wrong. I believe that green HB process would be
| 80%-90% efficient since the heat is re-used? I have read
| conflicting papers.
|
| Of course, HB is still a capex-heavy process.
|
| Maybe the 40% number is for fossil methane to ammonia?
| twawaaay wrote:
| I also think so. Rather than move hydrogen, move the
| electricity or the iron. Produce hydrogen on site and even on
| demand to get rid of most of the need to store/transport it.
|
| As to cost, who can quantify me the risks of having and
| transporting so much ammonia?
| gumby wrote:
| You said it: transporting, storing, and otherwise handling
| ammonia is easier than H2. Amd handling a lump of coke is even
| easier, which is why we started there.
| PaulHoule wrote:
| 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 power or solar complex like the ones
| being built in the North Sea or Australia you might be better
| off using hydrogen directly.
| philipkglass wrote:
| 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
| consumption) and save money too.
| conradev wrote:
| This is how Iceland exports the bulk of its hydroelectric
| energy, but they use aluminum
| frankus wrote:
| 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.
| tonyarkles wrote:
| 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.
| to11mtm wrote:
| > 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.
| adastra22 wrote:
| Anywhere you have water you have hydrogen.
| to11mtm wrote:
| 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...
| londons_explore wrote:
| 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.
| ClumsyPilot wrote:
| 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.
| rainbowzootsuit wrote:
| Hydrogen, being so small, penetrates directly through the
| molecular structure of steel and in the process causes
| embrittlement of the steel. Is a long distance H2
| pipeline a solved problem using alternate materials?
| KMag wrote:
| But the mass of the extracted oxygen exceeds the mass of
| the ammonia used, and we're only talking about 250 PSI to
| liquify anhydrous ammonia at room temperature. A large
| pressure vessel's mass is going to be negligible compared
| to the mass of the ammonia it holds. So, the same
| displacement ship traveling at the same speed can supply
| the production of more steel if you ship the ammonia to the
| iron ore instead of the other way around.
| photochemsyn wrote:
| 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.
| canadianfella wrote:
| [dead]
| boshomi wrote:
| 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 PS720
| million investment.
|
| * Decarbonisation without retiring of existing BF-BOF, reducing
| stranded assets.
|
| * After 5 years, PS1.28 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
| sacrosancty wrote:
| [dead]
| TEP_KimIlSung wrote:
| [dead]
| eutectic wrote:
| What about electrolysis?
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