Strontium Carbonate

Strontium Carbonate: Properties, Production, Applications, and Safety

Strontium carbonate (SrCO₃) is the most commercially important strontium salt. Supplied as a fine, white, odorless powder, it is prized for its role in pyrotechnics (deep red flames), ferrite magnets, specialty glass, and electronic ceramics. Abundant, relatively low in toxicity, and thermally stable, SrCO₃ is a versatile inorganic material for both legacy and emerging technologies.

Fast facts

Chemical formula: SrCO₃
Molar mass: 147.63 g/mol
CAS number: 1633-05-2
Appearance: White crystalline powder
Density: ~3.5 g·cm⁻³
Solubility: Practically insoluble in water; soluble in acids with CO₂ effervescence
Thermal behavior: Decomposes at high temperature (>1000 °C) to strontium oxide (SrO) and CO₂

How it’s made

Industrial strontium carbonate is produced primarily from celestite (SrSO₄) ore. The common route:

Reduction: Celestite is reduced with coke to strontium sulfide (SrS).
Carbonation: SrS is treated with sodium carbonate (or carbon dioxide and water) to precipitate SrCO₃, while forming soluble sodium sulfide or other by-products.
Purification & drying: Filtration, washing, and controlled drying yield high-purity SrCO₃.

Key properties

Physical & chemical

Insolubility in water makes it easy to handle and filter in wet processes.
Reactivity with acids produces soluble strontium salts and CO₂.
Thermal decomposition to SrO enables its use as a stoichiometric Sr²⁺ source in solid-state syntheses (e.g., strontium titanate, ferrites).

Functional

Color emitter in flames: Sr²⁺ gives an intense crimson/red color, central to fireworks and signal flares.
Electrical/ceramic behavior: Acts as a precursor to functional oxides used in electro-ceramics and magnets.

Applications

1) Pyrotechnics

Strontium carbonate is the workhorse red colorant in fireworks, road flares, and signal cartridges. It also serves as a chlorine-free alternative to strontium nitrate when lower hygroscopicity and reduced smoke are desired.

2) Ferrite magnets

SrCO₃ is a key raw material for strontium hexaferrite (SrFe₁₂O₁₉), widely used in loudspeakers, motors, magnetic separators, and inexpensive permanent magnets.

3) Specialty & electronic ceramics

Strontium titanate (SrTiO₃) and related perovskites for dielectric, thermoelectric, and optical applications start from SrCO₃.
Used in PZT-based piezoelectrics (as a dopant or modifier) and other advanced ceramic formulations.

4) Glass & legacy CRT/X-ray shielding

Historically, strontium carbonate was a major ingredient in CRT glass to block X-rays. While that market has largely vanished, SrCO₃ still appears in certain radiation-shielding glasses and specialty optical compositions.

5) Pigments, coatings & corrosion inhibition

Sometimes used as a whitening agent or as a precursor to other strontium salts in coatings with anti-corrosive functions.

Grades and quality control

Commercial grades are typically specified by:

Assay (SrCO₃ %): ≥ 98–99.5%
Loss on ignition (LOI): Indicates hydration/carbonation levels and purity
Insoluble residue & trace metals: Fe, Ba, Ca, Pb, etc., controlled for electronic/ceramic grades
Particle size distribution: Tailored for sintering behavior, magnet ferrite processing, or pyrotechnic flowability

High-end electronic/ceramic grades demand low alkali/alkaline-earth impurities and narrow PSDs to ensure reproducible sintering and dielectric properties.

Handling, storage, and safety

Hazard profile: Strontium carbonate is considered low-toxicity, but dust can irritate the respiratory tract and eyes.

Good practices:

Use dust control (local exhaust, masks/respirators when needed).
Wear gloves, goggles, and lab coats.
Store in tightly closed containers, in a dry place, away from strong acids (to avoid CO₂ release and dissolution).

Spills & disposal: Avoid generating dust; sweep or vacuum with HEPA filtration. Dispose of according to local regulations—generally not classified as hazardous waste but follow environmental guidelines.

Sustainability & market notes

Supply chain centers around countries with celestite deposits.
Post-CRT era: Demand shifted from glass to magnets, pyrotechnics, and electronic ceramics.
Emerging tech: Interest persists where strontium-based perovskites or ferrites are important (e.g., permanent magnet alternatives, functional oxides).

FAQs

Is strontium carbonate safe for consumer products?
Generally yes, when properly formulated and used (e.g., in magnets or ceramics). As a powder, it should be handled to minimize inhalation.

Why choose SrCO₃ over other strontium salts?
It is stable, inexpensive, and easy to handle, and it cleanly converts to SrO at high temperature for ceramic synthesis. In pyrotechnics, it provides strong coloration without introducing additional oxidizing anions.

Can SrCO₃ be used as a dietary supplement?
Nutritional applications typically use strontium citrate or other approved forms. Strontium carbonate itself is more common in industrial uses; any nutritional application must adhere to regulatory approvals.

Bottom line

Strontium carbonate remains a staple inorganic raw material: safe to handle with standard precautions, easy to process, and indispensable in fireworks, ferrite magnets, and advanced ceramics. Its role as a clean, high-purity Sr²⁺ source ensures it will continue to underpin both traditional and cutting-edge materials technologies.

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