Lime: Extraction
Why lime is cooked in kilns, not dug from mines
What this tab covers How it is mined, drilled or grown, and processed into a tradeable form: the main methods compared, their unit economics, by-products, and the companies that do this work globally and in India.Lime is made, not mined. High-purity limestone or dolomite is quarried, crushed and burned in kilns. The heat drives off carbon dioxide and leaves quicklime, calcium oxide. Adding a controlled amount of water in a hydrator yields hydrated lime, a dry calcium hydroxide powder. Plants sit next to their quarries because lime is heavy, cheap and absorbs moisture in transit. Some users burn their own lime, notably sugar refiners and pulp mills. Paper mills, carbide plants and some water works regenerate lime from their own wastes.
Lime is made by burning limestone or dolomite in kilns at high temperature, which releases CO2 and leaves quicklime. The main kiln types are rotary kilns, which take smaller stone and produce large volumes, and vertical shaft kilns, including efficient parallel-flow regenerative (Maerz) designs. Some quicklime is then hydrated. Many steel, sugar and paper plants run their own captive kilns. Because over half of a lime plant's CO2 comes from the stone itself, carbon capture is the main decarbonisation route.
Methods compared
| Method | Share of supply | Typical scale | Recovery / efficiency | By-products | Unit cost |
|---|---|---|---|---|---|
| Rotary kilns | Not published | Large plants make several hundred thousand tonnes a year; Graymont's new Malaysian site adds 390,000 t/yr of quicklime capacity (Graymont 2025) | Chemistry: about 1.8 t limestone per t quicklime (stoichiometric, pure stone) | Lime kiln dust (used in soil stabilisation) | US quicklime average value $260/t at plant (2025, USGS) |
| Vertical shaft kilns, including parallel-flow regenerative (PFR, Maerz) kilns | Not published | Caleras San Juan group capacity over 0.75 Mt/yr (Global Cement, 2026) | n/a | CO2-rich flue gas | Not available from the sources used |
| Hydration plants | 11 hydrating plants in the US in 2025 (USGS) | Graymont Malaysia: 70,000 t/yr hydrated lime capacity | About 1.32 t hydrated lime per t quicklime (chemistry: 74/56) | n/a | US hydrated lime average value $280/t (2025, USGS) |
| Captive and regenerated lime (paper, sugar, carbide, steel plants) | Regenerated lime excluded from USGS production totals | Small to medium kilns at host plants | n/a | CO2 used in sugar carbonation | Not available from the sources used |
How each method works
Rotary kilnsSized limestone is fed into a long inclined rotating tube, often with a preheater, and fired with coal, petcoke or gas. Rotary kilns handle smaller stone and give consistent, highly reactive lime for steel and chemicals.
Flexible and high quality; higher fuel use than shaft kilns.
USGS MCS 2026; Graymont Sustainability Report 2025 Vertical shaft kilns, including parallel-flow regenerative (PFR, Maerz) kilnsLump stone descends through a vertical shaft while hot gases rise. PFR kilns alternate firing between two shafts to recover heat. They are common in Europe and in new plants in Latin America; Caleras San Juan in Argentina runs four Maerz kilns.
Lower fuel use; needs larger, stronger stone.
Global Cement (Sep 2026) Hydration plantsQuicklime is mixed with a controlled amount of water in a hydrator to give dry calcium hydroxide powder for chemical, construction and environmental uses (USGS).
Safer to handle and store; extra step and water.
USGS MCS 2026; Graymont Sustainability Report 2025 Captive and regenerated lime (paper, sugar, carbide, steel plants)Pulp mills re-burn lime mud in their own kilns; sugar factories run small kilns for juice purification. Eight US companies made lime only for internal use in 2025 (USGS).
Avoids buying lime; closes with the host plant (a California sugar beet plant and its kiln closed in 2025).
USGS MCS 2026 Unit economics are indicative ranges from the sources named; costs vary widely by deposit, region and year.Who does it: global
| Company | Country | Activity | Volume | Year | Source |
|---|---|---|---|---|---|
| Graymont | Canada | lime and limestone (North America, Asia-Pacific) | 3.9 Mt lime produced (quicklime equivalent) | 2025 | Graymont Sustainability Report 2025 |
| Lhoist Private; volumes not published. | Belgium | lime and dolime; North American business combined with Martin Marietta in Aug 2026 | not published | 2025 | Global Cement (Sep 2026) |
| Carmeuse Private; volumes not published. | Belgium | lime; bought Cbb (Chile, 2025) and Caleras San Juan (Argentina, 2026) | not published | 2025 | Global Cement (Sep 2026) |
| Mississippi Lime Private; volumes not published. | US | high-calcium lime; carbon-capture project with Fortera | not published | 2026 | Global Cement (Sep 2026) |
| SigmaRoc Lime tonnage not published; Dolomitas produces about 3.5 Mt/yr of dolomite. | UK | lime and limestone in Europe; bought Dolomitas (Lithuania) | not published | 2026 | Global Cement (Sep 2026) |
Who does it: India
India made about 17 Mt of lime in 2025, the world's second largest after China (USGS). Producers range from steel-plant and sugar-mill kilns to small merchant kilns; company tonnages are not published. India also imports lime (6.4% of world import value, 2024, Comtrade).