Lime: Difference between revisions
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[[File:LimestoneCycle.jpg|500px|thumb|right| Image from | [[File:Limecycle.jpg|300px|thumb|right|The Lime(stone) cycle]] | ||
[[File:LimestoneCycle.jpg|500px|thumb|right| Image from [https://youtu.be/9LDG9cnGlDo Youtube video: "Limestone Cycle - limestone, quicklime and slaked lime"] (Chemistry for All - The Fuse School)]] | |||
==Basics== | ==Basics== | ||
Lime is an extremely versatile basic material. Limestone, often composed largely of calcium carbonate (CaCO3), can be burned in a kiln. | Lime is an extremely versatile basic material. Limestone, often composed largely of calcium carbonate (CaCO3), can be burned in a kiln. When heated to 900-1000C for several hours, it vents off carbon dioxide (CO2). What remains is mostly calcium oxide (CaO), also known as “quicklime” or “burnt lime”, a highly caustic material that is very “thirsty” for water. When combined with water – hydrated or “slaked” - the quicklime becomes calcium hydroxide or Ca(OH)2, often simply referred to as "lime". This material quickly reabsorbs CO2 and once again becomes calcium carbonate, completing the lime cycle. | ||
==Historical uses for hydrated lime:== | ==Historical uses for hydrated lime:== | ||
* mortar for construction | * mortar for construction | ||
* agriculture: to neutralize acidic soils to crop production | * agriculture: to neutralize acidic soils to crop production | ||
* "whitewash" - to protect wood (such as fences) or fruit | * "whitewash" - to protect wood (such as fences) or fruit trees from fungal infections | ||
* as a disinfectant: water treatment, dairy, as an antiseptic for livestock | * as a disinfectant: water treatment, dairy, as an antiseptic for livestock | ||
[[File:Lime slaking.jpg|500px|thumb|right| Slaking Lime]] | |||
==Historical uses for quicklime:== | ==Historical uses for quicklime:== | ||
| Line 16: | Line 20: | ||
* as a stabilizer in [[compressed earth blocks]] | * as a stabilizer in [[compressed earth blocks]] | ||
* for mixing with hemp, to make [https://en.wikipedia.org/wiki/Hempcrete "hempcrete"] | * for mixing with hemp, to make [https://en.wikipedia.org/wiki/Hempcrete "hempcrete"] | ||
* to fire the kiln, one could use the [[pyrolysis]] off-gases from [[biochar]] production | * to fire the kiln, one could use the [[pyrolysis]] off-gases from [[biochar]] production (see: [[Biochar-Lime Co-production System]]) | ||
* use waste heat to heat greenhouses, fish tanks, other facilities | * use waste heat (from burning and from slaking) to heat greenhouses, fish tanks, other facilities | ||
==Links:== | ==Links:== | ||
* Low-Tech Magazine: | * Low-Tech Magazine:[http://www.lowtechmagazine.com/2013/09/lime-kilns.html "Burning the Bones of the Earth: Lime Kilns"] | ||
* http://en.wikipedia.org/wiki/Lime_%28material%29 | * Wikipedia: [http://en.wikipedia.org/wiki/Lime_%28material%29 Lime (material)] | ||
* Practical Action: | * Practical Action: [https://answers.practicalaction.org/our-resources/item/lime-an-introduction "Lime - an introduction"] | ||
* Practical Action: "Lime - Kiln Designs" | * Practical Action: [http://practicalaction.org/lime-kiln-designs "Lime - Kiln Designs"] | ||
* Practical Action: [http://practicalaction.org/a-small-lime-kiln-for-batch-and-continuous-firing "A Small Lime Kiln for Batch and Continuous Firing"] | |||
* Practical Action: [https://answers.practicalaction.org/our-resources/item/how-to-build-a-small-vertical-shaft-lime-kiln "How to Build a Small Vertical Shaft Lime Kiln"] | |||
* Nice report showing the comprehensive process, and batch + continuous [[kiln]] design descriptions - [http://www.gate-international.org/documents/publications/webdocs/pdfs/g06sme.pdf]. Source: GATE - | |||
[[File:SmallScaleLime_GATE.pdf]] | |||
[[Category:Materials]] | |||
[[Category:Housing and construction]] | |||
[[Category:Food and Agriculture]] | |||
Latest revision as of 06:35, 26 April 2018
Image from Youtube video: "Limestone Cycle - limestone, quicklime and slaked lime" (Chemistry for All - The Fuse School)
Basics
Lime is an extremely versatile basic material. Limestone, often composed largely of calcium carbonate (CaCO3), can be burned in a kiln. When heated to 900-1000C for several hours, it vents off carbon dioxide (CO2). What remains is mostly calcium oxide (CaO), also known as “quicklime” or “burnt lime”, a highly caustic material that is very “thirsty” for water. When combined with water – hydrated or “slaked” - the quicklime becomes calcium hydroxide or Ca(OH)2, often simply referred to as "lime". This material quickly reabsorbs CO2 and once again becomes calcium carbonate, completing the lime cycle.
Historical uses for hydrated lime:
- mortar for construction
- agriculture: to neutralize acidic soils to crop production
- "whitewash" - to protect wood (such as fences) or fruit trees from fungal infections
- as a disinfectant: water treatment, dairy, as an antiseptic for livestock
Historical uses for quicklime:
- main industrial uses today: as a steel fluxing agent and in flue gas desulphurization. Other: production of fiberglass, pulp and paper, aluminium, uranium, copper and gold.
Product ecology
- as a stabilizer in compressed earth blocks
- for mixing with hemp, to make "hempcrete"
- to fire the kiln, one could use the pyrolysis off-gases from biochar production (see: Biochar-Lime Co-production System)
- use waste heat (from burning and from slaking) to heat greenhouses, fish tanks, other facilities
Links:
- Low-Tech Magazine:"Burning the Bones of the Earth: Lime Kilns"
- Wikipedia: Lime (material)
- Practical Action: "Lime - an introduction"
- Practical Action: "Lime - Kiln Designs"
- Practical Action: "A Small Lime Kiln for Batch and Continuous Firing"
- Practical Action: "How to Build a Small Vertical Shaft Lime Kiln"
- Nice report showing the comprehensive process, and batch + continuous kiln design descriptions - [1]. Source: GATE -