Comments on: Why bother heating up the limestone?

By: Jem Cooper

Jem Cooper — Tue, 09 Feb 2010 10:10:57 +0000

The problem with using powdered calcium carbonate (limestone) is not the cost of grinding but its insolubility. The ocean is supersaturated with calcium carbonate at the surface by a factor of about 4 on the ion concentration multiple ([CO3--] times [Ca++]) because photosynthesis removes carbon dioxide from the water thus increasing the ratio of carbonate [CO3--] to bicarbonate [HCO3-] ions as the chemistry adjusts to keep an equal number of negative and positive ions. At greater depths usually at least 1000 metres the decomposition of sinking organic matter releases carbon dioxide thus reducing making calcium carbonate soluble. Even then the rate of dissolving is very low but below the calcite compensation depth (typically 400 metres) no calcium carbonate sediment accumulates because the rate of dissolving equals the rate of arrival in sinking skeletal remains. Water from the ocean depths takes a very long time to return to the surface where the dissolved calcium carbonate can intereact with atmospheric carbon dioxide.

By: Kiko

Kiko — Tue, 08 Dec 2009 12:57:52 +0000

I’m puzzled: why not use slag? It is full of CaO, meaning it would act just as lime, without any need for burning limestone (or I am mistaken?). True it contains also other oxides like Al2O3 but I don’t think it would be such a problem?
For the moment, it is a by-product of iron production and many uses had to be found as it is strictly illegal to dump it, due to the basification of soils when you do that, but it would be an elegant way to reduce the impact of a necessary industry (and there are sources of slag all other the world, mainly near the see as it is less expensive to have a blast furnace near the supply arrival point).
Perhaps you could discuss with Ulcos project leaders? (NB: Ulcos is a European initiative uniting iron producers to reduce the CO2 emissions of the iron processing)

By: shwetha s

shwetha s — Mon, 12 Oct 2009 05:50:28 +0000

why not mix up two research together… evensky spraying can be used as one of the technique to reduce the amount of co2 in atmosphere and also to some extent organic farmaing which wil benefit the mankind economically and also helps us the scientific manner..i think merging of more techniques is one of the useful way to come out of this problem….