Adding Crushed Rock to Farmland Pulls Carbon Out of the Air

Re:Adding Crushed Rock to Farmland Pulls Carbon Out of the Air by denton-scratch on Wednesday October 25, 2023 @01:58PM (#38015940)

So I guess you end up with finely-divided carbonate.

I didn't notice any mention of how long it takes powdered basalt to weather down. Is that over a year?

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Re:Adding Crushed Rock to Farmland Pulls Carbon Out of the Air by vonwolfhausen on Wednesday October 25, 2023 @02:39PM (#38016557)

Can be <5 years if it is super fine (~25um) or >20 years if it is coarse (minus 3/8" fines).

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Re:Adding Crushed Rock to Farmland Pulls Carbon Out of the Air by kisamoto on Wednesday October 25, 2023 @03:06PM (#38016886)

To reach maximum sequestration rate I thought it was much longer than that (~95% within 30 years at 3um). Where did you get your numbers from (curious, always looking for more sources)?

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Re:Adding Crushed Rock to Farmland Pulls Carbon Out of the Air by denton-scratch on Wednesday October 25, 2023 @06:09PM (#38019009)

I seem to be wrong about the result of basalt-weathering being carbonates.

https://en.wikipedia.org/wiki/Basalt#Weathering

It seems that basalt consists mainly of metal oxides, predominantly Fe, Ca, Mg and Al. How does carbonic acid from rain get bound into basalt, without dissolving in the next rainstorm?

(My knowledge of chemistry is restricted to "A" level, what Americans would call High School; and I've forgotten it all, because it was 40 years ago).

The article says that basalts weather down into clays, which aren't carbonates.

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