Talk:Lime kiln

Wood Ash

The traditional process of burning lime would leave a lot of wood ash mixed in with the lime, but its presence is ignored in the discussion. Is this ash a contaminant? Is its presence negligible?

Although wood is, indeed, added to a lime kiln or limepit, the limestone is usually of a coarser consistency, sometimes even chunks or blocks of limestone are used. The wood ash is removed from the kiln, and the limestone chunks/blocks are also removed and only then crushed.Davidbena (talk) 03:30, 24 July 2019 (UTC)

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This entry could do with expansion and probably correction

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My dictionary says the process here is "carbonation", but my dictionary of science says "carbonation" is "treatment with CO2 usually giving a carbonate". But here a carbonate is the raw material. could someone clear this up? -- Tarquin

Clear-up carbonation...

Either the article has been edited since Tarquin remarked 'carbonation is treatment with CO2', or an easy error was made - seing one word where a different one was actually present. The article says 'calcination', not 'carbonation'. Tarquin's understanding of Carbonation is correct.

UK Focus

This article is very focused on lime kilns in the UK/Europe, and does not provide any historical references to the many lime kilns in the United States or other countries around the world. —Preceding unsigned comment added by Thefox226G (talk • contribs) 20:38, 11 February 2010 (UTC)

Broken down "Early kilns" to add geographic specific subsections. I also organised the photos into galleries as they were all over the place. Feel free to add sections for other countries or to expand poor lonely Belgium there. Citizen D (talk) 01:29, 11 July 2012 (UTC)

Coal as fuel

Once coal became available it was used as a fuel. George Stephenson built the limeworks at Ambergate to use the slack from his coal mines at Clay Cross.This lime would be useful to farmers but how would be affected as a building material since the coal ash would be a pozzolan?2.28.217.186 (talk)

Strange claim

" The manufacture of one tonne of calcium oxide involves decomposing calcium carbonate, with the formation of 785 kg of CO2 in some applications, such as when used as mortar; this CO2 is later re-adsorbed as the mortar goes off. "

So if you mix up a large batch of lime mortar, and build a brick wall with it, how does it absorb hundreds of kilograms of carbon dioxide from the atmosphere ? This seems highly implausible. How does the carbon dioxide get into the mortar which is nowhere near the surfaces exposed to the air ? Tallewang (talk) 08:55, 22 October 2013 (UTC)

It takes a very long time to do this. Very long. I remember reading (a few years back) that some of the WWII German fortifications still weren't thought to be fully cured, as they were so thick and originally poured so quickly.

Lime and cement mortars have two curing phases. Firstly they "set", mostly from hydration by, and by losing through evaporation, the mixture water. This is quick: hours and days. However they're not at full strength yet. Then they "cure" by absorbing CO₂. This takes longer: months or years, and it's how they achieve full strength. Sometimes heavily stressed foundations, such as bridge piers, have to wait for this. The atmosphere is full of CO₂ and mortar, especially lime, is fairly permeable so it's the reaction speed that's the limit, not the availability of the reagent.

Note also that mortars are mostly an inert sand filler and there's only a smaller proportion of the active cement binder. Andy Dingley (talk) 09:57, 22 October 2013 (UTC)

Old lime kilns

Add to references: https://au.news.yahoo.com/thewest/wa/a/30494628/family-keep-old-lime-ways-burning/ Which is a currently working commercial old kiln. Oaec 60.230.194.64 (talk) 22:55, 6 January 2016 (UTC)

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Math error in section "CO2 Emissions"

"If the heat supplied to form the lime (3.75 MJ/kg in an efficient kiln) is obtained by burning fossil fuel it will release CO2: in the case of coal fuel 295 kg/t; in the case of natural gas fuel 206 kg/t. The electric power consumption of an efficient plant is around 20 kWh per tonne of lime. This additional input is the equivalent of around 20 kg CO2 per ton if the electricity is coal-generated."

Obviously this is wrong: turning coal into electricity into heat is not more efficient than turning coal directly into heat.

Using the value of 0.9 Joules / (grams*degC) as the heat capacity of CaCO3, I calculate that heating one tonne of CaCO3 to 1000 degC requires 250kWh, not 20kWh. 2601:98A:4400:2E50:F563:2062:9BAD:7358 (talk) 20:53, 11 March 2023 (UTC)