Limestone Kiln, Sedgwick Park
The gate to this very small park is chained, but not locked. Feel free to open the gate and park up to 5-6 vehicles in the parking lot, or pull one vehicle up in front of the gate on the roadside and walk in. The parking lot is not likely to be plowed in winter.
Requirements for Logging :
Send the CO an email with the following information:
"Apparently the park has been closed since 2020 at the beginning of covid-19. Construction for restoration started in 2016 but they haven't touched it since. Still interesting to see and read about. You are able to answer all but the first question without entering the park if the closed sign is still in place. Do your best."
1. The approximate diametre of the opening at the top of the kiln.
2. The approximate depth of the kiln from top to bottom.
3. Are the walls of this lime kiln comprised of brick or rock ?
4. Is the kiln built into a mound of earth or a pile of rocks ?
5. Why do you suppose this kiln is no longer in use today? (Read the description and use your best educated guess.)
Extras (optional activities):
1. Take a picture of yourself at the kiln and post with your log.
2. Take a tiny bit of vinegar (ascetic acid) with you. Find a piece of limestone and pour a few drops of the vinegar on the rock to see if you get a chemical reaction - the rock will bubble and fizz as the carbon dioxide is released. (Hint : limestone often contains fossils and there are plenty of fossils at GZ).
3. Pick up a piece of limestone and rub it between your fingers to see how soft the dust is. It should feel like chalk dust.
Note : Although there are no signs saying that you cannot collect rocks at this site, we are asking that you take only photographs and leave the rocks here at this historically significant site. Thanks !
The Geology of Limestone
Limestone is a sedimentary rock (laid down in layers over time), composed of the element calcium carbonate (CaCO3).
Limestone is found everywhere in Canada, but is less prevalent in areas where the Canadian Shield granite dominates the landscape. Limestone is more common in the lowlands of the Great Lakes, just south of the Shield in locations where ancient marine environments once existed.
Limestone is primarily comprised of the shells of sea creatures that were crushed and solidified, trapping carbon dioxide in the process. This is why when limestone is heated (calcination), to temperatures of between (402-898°C), carbon dioxide is released. The remaining product is then called quicklime. Quicklime combined with water produces slaked lime and hydrated lime (Ca[OH]2). Historically, lime was used by farmers in fertilizing fields and increasing crop production. Lime neutralizes acidic soil. But more importantly, lime was used in mortar for building. These days lime is used in the steel, pulp and paper, and mining industries as well as for water and sewage treatment and removal of sulphur dioxide from smelter-stack gases and thermal power-plant emissions.
Kilns were built on the side of a small hill or knoll and lined with refractory (heat resistant) stones, such as sandstone and then laid in mortar. Later refractory bricks were used to line the kilns. Kiln shape and size was pretty much standard for efficiency. Most kilns were between 7 - 13.5 feet in diametre but varied in depth. They were loaded from the top with layers of limestone and wood or limestone and coal. When loading was complete, the kiln was fired at the bottom, through an opening called an "eye", and the fire gradually spread upwards through the charge. When burnt through, the lime was cooled and raked out through the base. Fine ash dropped out and was shoveled away.
Fist-sized lumps of limestone had to be thrown by hand into the top of the kiln. Only lumps could be used, because the charge needed to "breathe" during firing. Because of this, the size of kilns were pretty much standard. Anything over 8 feet in diameter was not efficient as the half-burned charge would be likely to collapse under its own weight, extinguishing the fire. Kilns always made 25–30 tonnes of lime in a batch. Typically the kiln took a day to load, three days to fire, two days to cool and a day to unload, so it was a one-week job of manual labour and 24-7 monitoring for a group of men. The workers would camp out by the kiln, risking the danger of burns, or even rolling into the kiln while sleeping and burning to death. Firing the kiln was dangerous. The caustic gases emitted could burn the skin and eyes. Producing a good batch of quicklime was usually a trial and error production as the amount of wood or coal would vary from batch to batch. Efficiency was affected by many factors including temperature differences between the centre of the charge and the material close to the sandstone or brick walls, as well as the amount of underburned versus finished quicklime. In this antiquated kiln, the lime would also get adulterated with ash from the burned wood and be less "pure".
We are linking a fantastic three-part video on a group of people who tried the old-fashioned way of producing a batch of quicklime by firing a century old limestone kiln. Enjoy !
Link: https://www.youtube.com/watch?v=IJpZsvYygF8
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Sources :
http://www.thecanadianencyclopedia.ca/en/article/limestone/
https://ballincollig.wordpress.com/limekilns/
https://en.wikipedia.org/wiki/Lime_kiln
http://www.limehousekilns.ca/history.htm
http://www.lowtechmagazine.com/2013/09/lime-kilns.html "Burning the Bones of the Earth"
http://www.canalcenter.org/historyBehindLimeKiln.php
http://www.ucl.ac.uk/~ucfbrxs/limes/Kilns.htm