Process

Calcination

Heating a material below its melting point to drive off a volatile component — classically CO₂ from limestone.

Calcination heats a solid enough to decompose it, without melting it. The defining example is limestone: heated above about 900 °C, calcium carbonate breaks down into calcium oxide and carbon dioxide, the gas escapes, and what remains is quicklime.

It is among the oldest chemical processes deliberately operated at scale, and it remains one of the largest by tonnage.

Uses

The dominant use is making lime from limestone, which feeds cement manufacture, steelmaking and every application of quicklime. By tonnage this is among the largest chemical reactions carried out anywhere.

Calcination also produces alumina from aluminium hydroxide on the way to aluminium metal, drives water from gypsum to make plaster, and converts a range of ores and hydroxides to oxides in preparation for reduction. In catalyst and ceramic manufacture it is used to decompose precursors and stabilise the resulting powder before forming.

Medium confidence Weak evidence

How we know: checked recently · only one source, so there is nothing to cross-check it against · stated directly by the source.

How this connects

Where a connection has been confirmed by an outside reference, that reference is named beside it.

takes as input

Limestone — rock · heated until the carbonate decomposes to lime and carbon dioxide
Gypsum — mineral · gently calcined to plaster of Paris, a far lower temperature than lime burning
Clay — material · supplies the silica and alumina that combine with lime in the cement kiln
Gypsum plaster — material · at around 150 °C, which is driving off water rather than decomposing a carbonate — so no carbon dioxide comes out of the rock
Lime mortar — material · at around 900 °C, which does decompose the carbonate, and the mortar reabsorbs a large part of it over the following years
Bone — material · at around 1,000 °C, which burns off the collagen and leaves bone ash — essentially pure calcium phosphate
Chalk — rock · burned to quicklime exactly as any limestone is, and it was the lime of the regions where chalk is what the ground is made of

produces

Quicklime — compound · the solid residue once carbon dioxide has been driven off
Portland cement — material · as clinker, ground with gypsum to retard the set
Ferrite — material · the step before, where the milled oxides react together into the ferrite phase
Zirconia — compound · from zircon sand, dissociated at high temperature and then stabilised with yttria or magnesia to stop it shattering as it cools through a phase change
Tungsten carbide — compound · tungsten powder and carbon reacted at 1,500 °C, then sintered with cobalt as a binder into the tool the trade actually buys
Lithium iron phosphate — compound · lithium, iron and phosphate precursors fired together under an inert atmosphere, with a carbon source that leaves the conductive coating each particle needs
NMC cathode — compound · a mixed hydroxide precursor co-precipitated first so the three metals are evenly distributed, then fired with lithium — and the precursor step is where most of the quality is decided
Lithium cobalt oxide — compound · lithium carbonate and cobalt oxide fired together, which is the simplest of the cathode syntheses and part of why it was first

Sources

Material World
Our own writing

Questions this page answers

What is produced from Calcination?

Where it comes from, and what it becomes

Follow Calcination back to what it starts as, and forward into what it becomes. Each step is a documented one — a real route material takes, not a chain of inference.

Upstream — what it comes from

Calcination → takes as input (at around 150 °C, which is driving off water rather than decomposing a carbonate — so no carbon dioxide comes out of the rock) → Gypsum plaster → is produced by (rehydrating back into the mineral it was calcined from, in minutes rather than weeks, which is why plaster is mixed in small batches) → Hydration → takes as input (the reactive component — everything else in a concrete mix is aggregate, water, or an admixture adjusting how this reaction runs) → Portland cement → is sourced from (the calcium source, fired with clay to make clinker) → Limestone → is composed of → Calcite
Calcination → takes as input (at around 900 °C, which does decompose the carbonate, and the mortar reabsorbs a large part of it over the following years) → Lime mortar → is produced by (and mostly it does not hydrate at all: it hardens by absorbing carbon dioxide from the air over months and years, turning back into the limestone it was burned from) → Hydration → takes as input (the reactive component — everything else in a concrete mix is aggregate, water, or an admixture adjusting how this reaction runs) → Portland cement → is sourced from (the calcium source, fired with clay to make clinker) → Limestone → is composed of → Calcite
Calcination → takes as input (heated until the carbonate decomposes to lime and carbon dioxide) → Limestone → is sourced from (precipitated from it, mostly by organisms building shells and skeletons out of dissolved calcium and carbonate) → Seawater → is composed of (about 96.5 per cent by mass — seawater is 3.5 per cent dissolved solids and the rest of it is this) → Water
Calcination → takes as input (burned to quicklime exactly as any limestone is, and it was the lime of the regions where chalk is what the ground is made of) → Chalk → is sourced from (built from dissolved calcium and carbonate by algae in warm shallow Cretaceous seas, and accumulated at a few centimetres a millennium) → Seawater → is composed of (about 96.5 per cent by mass — seawater is 3.5 per cent dissolved solids and the rest of it is this) → Water
Calcination → takes as input (supplies the silica and alumina that combine with lime in the cement kiln) → Clay → is sourced from (clay is chiefly what feldspar becomes when it weathers) → Orthoclase
Calcination → takes as input (at around 1,000 °C, which burns off the collagen and leaves bone ash — essentially pure calcium phosphate) → Bone → is composed of (carbonated hydroxyapatite in crystals a few nanometres thick — small enough to contain no flaw big enough to start a crack, which is most of why bone is tough) → Apatite

These are the most distinct paths back. Calcination can be traced through others besides.

Downstream — what it becomes

Calcination → produces (the solid residue once carbon dioxide has been driven off) → Quicklime → is a component of (as calcium oxide within the clinker phases, not as free lime) → Portland cement → is a component of (the binder — the expensive, energy-intensive, chemically active part) → Concrete → is a component of (with steel put where the tension is) → Reinforced concrete → is associated with (after it rather than during — Portland cement is 1824 and reinforcement is the 1860s onward, and the Romans had concrete with no reinforcement at all) → Industrial Revolution complete chain
Calcination → produces (as clinker, ground with gypsum to retard the set) → Portland cement → is a component of (the binder — the expensive, energy-intensive, chemically active part) → Concrete → is a component of (with steel put where the tension is) → Reinforced concrete → is associated with (after it rather than during — Portland cement is 1824 and reinforcement is the 1860s onward, and the Romans had concrete with no reinforcement at all) → Industrial Revolution complete chain
Calcination → produces (lithium, iron and phosphate precursors fired together under an inert atmosphere, with a carbon source that leaves the conductive coating each particle needs) → Lithium iron phosphate → is used in (in more than half of world cell production, and in almost all stationary storage — the cathode chosen where mass does not bind and price and fire risk do) → Lithium-ion cell → is used in (and portable computing came first by two decades) → Electronics manufacture → is associated with (and the supply chain it produced is the deepest and most concentrated in the world economy) → The semiconductor era complete chain
Calcination → produces (a mixed hydroxide precursor co-precipitated first so the three metals are evenly distributed, then fired with lithium — and the precursor step is where most of the quality is decided) → NMC cathode → is used in (in long-range vehicles and anything that has to be carried, where the requirement is energy per kilogram and no phosphate cathode competes) → Lithium-ion cell → is used in (and portable computing came first by two decades) → Electronics manufacture → is associated with (and the supply chain it produced is the deepest and most concentrated in the world economy) → The semiconductor era complete chain
Calcination → produces (lithium carbonate and cobalt oxide fired together, which is the simplest of the cathode syntheses and part of why it was first) → Lithium cobalt oxide → is used in (in the smallest cells only — phones, laptops, cameras — where volume is the constraint and a few hundred cycles is a long enough life) → Lithium-ion cell → is used in (and portable computing came first by two decades) → Electronics manufacture → is associated with (and the supply chain it produced is the deepest and most concentrated in the world economy) → The semiconductor era complete chain
Calcination → produces (the step before, where the milled oxides react together into the ferrite phase) → Ferrite → is used in (and its most consequential use is historical: core memory was the working memory of computers for twenty years, which is why a memory image is still called a core dump) → Electronics manufacture → is associated with (and the supply chain it produced is the deepest and most concentrated in the world economy) → The semiconductor era complete chain

These are the most distinct paths onward. Calcination ends up in others besides.