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Kelly

(1)

Very interesting article, I've always wondered about the various limekilns we see just about everywhere, and what their purpose and history is.

One minor correction: you say of quicklime, "It caught fire easily – sometimes too easily – and was used to make an early, high-intensity lamp for the stage – the original limelight."

Of course, quicklime is not flammable - if it were, it would be consumed in the kiln! A 'limelight' is created by heating calcium oxide to a very high temperature - via an external heat source, such as a flame - until the calcium oxide gives off bright light via incandescence. The quicklime does not - and cannot - burn.

Joel

(2)

Quicklime is non-flammable, but there is yet another substance named "lime" that this article didn't mention.

Over-burned lime (calcium carbide) releases acetylene when it gets wet. Acetylene is very flammable, and a lot of heat is evolved when lime is "slaked", so I could imagine a wagonload of lime catching fire spontaneously, if the limeburners had originally used too much fuel and conditions were humid.

This method of making acetylene is how blowtorches were fueled; the evolving gas would push down the level of water in the container, regulating the pressure automatically using gravity. It's a neat system, if not particularly efficient.

Matthas

(3)

The CO2 emissions from the cement industry are not becaue they use so much power for the milling. It is the CO2 which is set free in the precalciner, exactly the same process as burning lime. For 1.6 tons of raw meal you get one ton of clinker. The remainder is mostly CO2 which leaves trough the stack. A cement plant which produces 10000 tons of clinker a day will release 6000 tons of CO2 . Depending on the fuel it will a bit more. The emissions caused energy consumption of the mills are marginal if you compare to this numbers.
Cement plants nowadays use large amount of secondary fuel. The burn all kinds of waste. As the temperature are so high, even some toxic fuel can be used.
By the ton modern cement plants are more energy efficient and the gas can be cleaned in several stages. First plants will generate electricity out of waste heat.
Also there are many types of cement not only Portland cement. Some have similar properties like the Roman cement.

Michael Gambill

(4)

A fascinating look at the historical significance of this technology. Understanding past advancements equips us to make informed decisions about today's technology. It is a point that I regularly make with my high school history students. Well done and thanks.

Lindsapril

(5)

Loved this article. I am currently writing a masters thesis on lime kiln use in early settlement Saskatchewan - it was nice to see a concise and interesting write up on the traditions these homesteaders in Saskatchewan were drawing their knowledge and skill from. Thank you!

Himbeerkuchen

(6)

Thanks a lot for the article. This is a very interesting one, as it clearly shows that in the 'good old days' not everything was sustainable either. Especially note the 'toxic fumes' bits...

However, the footprint is still different. Just compare those relatively few kilns with the incredible numbers and area of industrial ruins and wasteland that we are leaving to our descendants. A shame.

RobD

(7)

Nice article.

As a variation:
In our sea-side village in Holland a kiln (one of many in the past)has remained that used shells as raw material; no limestone in this country.

Peter Dew

(8)

Presuming that slaking lime refers to adding water to the quick-lime to make hydrated lime or calcium hydroxide for mortar, is there a specific term for burning the limestone to make un-hydrated or quick-lime ? It doesn't seem right that they simply burnt or burned limestone, which I understand may have been a key industry based on salvaging it from ruins in Medieval and Renaissance Rome.

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