STRONTIUM CARBONATE
STRONTIUM CARBONATE (SrCO3) is the carbonate salt of strontium, which appears as a white or grey powder.
IUPAC name: Strontium Carbonate
Synonyms: Carbonic acid strontium salt, Strontianite
CAS Number: 1633-05-2
EC number: 216-643-7
Hill Formula: CO₃Sr
Chemical properties
Strontium carbonate is a white, odorless, tasteless powder.
Properties
Chemical formula: SrCO3
Molar mass: 147.63 g·mol−1
Appearance: White powder
Odor: Odorless
Density: 3.5 g/cm3
Melting point: 1,494 °C (2,721 °F; 1,767 K) (decomposes)
Solubility in water
0.0011 g/100 mL (18 °C)
0.065 g/100 mL (100 °C)
Solubility product (Ksp): 5.6×10−10
Solubility in other solvents: Soluble in ammonium chloride
Slightly soluble in ammonia
Magnetic susceptibility (χ): −47.0·10−6 cm3/mol
Refractive index (nD): 1.518
STRONTIUM CARBONATE (SrCO3), commercially produced from strontium sulfate (SrSO4) contained in celestite ores, is one of the most essential raw materials for producing other strontium compounds and is widely used in various industrial applications.
STRONTIUM CARBONATE has two main applications: as an additive in the production of color television tubes and as a constituent in the production of permanent ceramic ferrite magnets.
Other applications include manufacturing zinc, glass, pyrotechnics, paints, dryers, and strontium metal.
The consumption of Strontium Carbonate doubled (U.S. Geological Survey, 2021) from 2008 to 2018.
Due to the rapid expansion of the electric vehicle market, this growth in demand is expected to continue.
STRONTIUM CARBONATE is used to produce ferrite magnets, which are used in various electronic devices such as motors, speakers, and generators.
Additionally, Strontium Carbonate is used as an ingredient for specialty chemicals and pigments in industries such as paints, coatings.
Preparation of Strontium Carbonate
Besides being a naturally occurring mineral, strontium carbonate is prepared synthetically in one of two processes.
Both processes start with naturally occurring celestine, a mineral form of strontium sulfate (SrSO4).
In the “black ash” process, celesite is roasted with coke at 1100–1300 °C to form strontium sulfide.
The sulfate is reduced, leaving the sulfide:
SrSO4 + 2 C → SrS + 2 CO2
A mixture of strontium sulfide with either carbon dioxide gas or sodium carbonate then forms a precipitate of strontium carbonate.
SrS + H2O + CO2 → SrCO3 + H2S
SrS + Na2CO3 → SrCO3 + Na2S
In the “direct conversion” or double-decomposition method, a mixture of celesite and sodium carbonate is treated with steam to form strontium carbonate with substantial amounts of undissolved other solids.
This material is mixed with hydrochloric acid, which dissolves the strontium carbonate to form a solution of strontium chloride.
As in the black-ash process, carbon dioxide or sodium carbonate is used to re-precipitate strontium carbonate.
Uses
Nitric acid reacts with strontium carbonate to form strontium nitrate.
The most common use is as an inexpensive colorant in fireworks.
Strontium and its salts emit a brilliant red color in flame. Unlike other strontium salts, carbonate salt is generally preferred because of its cost and the fact that it is not hygroscopic. Its ability to neutralize acid is also beneficial in pyrotechnics.
Another similar application is in road flares.
Strontium Carbonate is used for electronic applications.
Strontium Carbonate is used to manufacture color television receivers to absorb electrons resulting from the cathode.
Strontium Carbonate is used to prepare iridescent glass, luminous paint, strontium oxide, and strontium salts, as well as to refine sugar and certain drugs.
Strontium Carbonate is widely used in the ceramics industry as an ingredient in glazes.
Strontium Carbonate acts as a flux and modifies certain metallic oxides’ color.
Strontium Carbonate has some properties similar to barium carbonate.
Strontium Carbonate is also used to manufacture strontium ferrites for permanent magnets, which are used in loudspeakers and door magnets.
Strontium carbonate also makes superconductors such as BSCCO and electroluminescent materials.
It is first calcined into SrO and then mixed with sulfur to make SrS:x, where x is typically europium.
This is the “blue/green” phosphor sensitive to frequency and changes from lime green to blue.
Other dopants, such as gallium or yttrium, can also be used to get a yellow/orange glow instead.
Because of its status as a weak Lewis base, strontium carbonate can produce many different strontium compounds by simply using the corresponding acid.
Microbial precipitation
The cyanobacteria Calothrix, Synechococcus, and Gloeocapsa can precipitate strontian calcite in groundwater.
The strontium exists as strontianite in a solid solution within the host calcite with a strontium content of up to one percent.