Middle School Lime Kiln Project

Last Wednesday, our 6th & 7th Grade came together during main lesson to build a primitive lime kiln. In Waldorf Schools a kiln is typically built during the Inorganic Chemistry block to demonstrate the archetypal chemical process of transforming calcium carbonate into quicklime. The experiment requires that calcium carbonate (substances such as limestone, marble, sea shells, & chalk) are burned in a kiln where the temperature reaches above 1800°F.  Limestone is a unique mineral because it’s derived from the animal kingdom, and the process of burning it is very similar to those used to make lime mortar, which is a building material, and lime milk, which is used in fresco paintings. We used marble in our kiln — marble is limestone that has been subjected to heat and pressure, causing it to become recrystallized. To build our kiln we dug out a foundation, leveled it, and stacked fire stone bricks. The kiln is built to burn all day & night, and in the morning the materials placed should be transformed. Although I have no photographic evidence of the transformation, I’m happy to report that the kiln was a success — the students were even able to add sand to the quicklime to slake it and make a mortar. For deeper insights, I encourage you could ask any of our middle school students for an elaborate explanation.

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