XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 1297
INTRODUCTION
Properties and Uses of Strontium
Strontium, identified by the symbol Sr and atomic number
38, is an alkaline earth metal classified as a critical raw mate-
rial (CRM) since 2020 by the European Union (European
Commission, 2023). It is a commonly occurring element,
being the 15th most abundant element on Earth’s crust.
Strontium’s physical and chemical attributes (see Table 1)
closely resemble those of its neighbouring elements in the
periodic table, calcium, and barium (MacMillan et al.,
2000).
Strontium is a highly reactive element. Consequently,
it is never found in its pure state due to its rapid oxidation
upon exposure to air, leading to the formation of diverse
minerals. The most common strontium-bearing minerals
are celestine (SrSO4) and strontianite (SrCO3), the prin-
cipal sources of strontium through mining. More details
about the strontium-bearing minerals and their properties
are detailed in the following section.
The primary use for strontium in previous decades was
to produce a special glass for colour television cathode ray
tubes (CRTs) capable of preventing the emission of harmful
X-rays. However, with the rapid advancements in flat-panel
technologies for television and computer screens, CRTs
have become obsolete, resulting in a declining demand for
strontium carbonate in this sector. Nevertheless, strontium
is still utilised in the glass industry to improve the optical
and mechanical properties of materials, enhance transpar-
ency, increase refractive index, and reduce chromatic aber-
ration in optical lenses.
Nowadays, the main use of strontium compounds
is in pyrotechnics, drilling fluids and ceramic magnets
(European Commission, 2023 USGS, 2023). In pyrotech-
nics, strontium is used for the brilliant reds in fireworks and
warning flares and in some ‘glow-in-the-dark’ paints and
plastics. In the case of drilling fluids, strontium sulphate
and strontium carbonate are utilised as additives to enhance
drilling performance in the oil and gas sector, preventing the
formation of scales, such as calcium carbonate and barium
sulphate. Finally, strontium ferrite magnets (SrFe12O19) are
commonly used in small motors, loudspeakers, electronics
and toys because of their favourable magnetic properties
and low cost. Other uses of strontium include medicine,
where strontium compounds such as strontium ranelate
have been used for their potential to increase bone density
and reduce the risk of fractures in postmenopausal women
with osteoporosis.
Strontium Minerals
Strontium is primarily found in various minerals, with the
main ones being celestine (strontium sulphate, SrSO4),
strontianite (strontium carbonate, SrCO3), strontium fluo-
ride (SrF2), strontium molybdate (SrMoO4), and strontium
titanate (SrTiO3). These minerals are commonly located in
diverse geological formations, including sedimentary, igne-
ous, and metamorphic rocks.
Among these minerals, celestine stands out as the most
abundant and significant source of commercial strontium.
Although celestine is a relatively common mineral in sedi-
mentary environments, large economically exploitable
deposits are rare. World strontium reserves exceed one bil-
lion tons distributed between the USA, Argentina, China,
Iran, Mexico and Spain (Nesse, 2017). Strontianite is the
second most abundant strontium mineral, and it is utilised
for producing various strontium compounds like strontium
carbonate and strontium chloride. Although less common,
strontium fluoride, strontium molybdate, and strontium
titanate find industrial applications such as in glass, ceram-
ics, and pigments manufacturing.
Strontium is a relatively abundant element however, it
is not commonly found in large concentrations in a single
Table 1. Properties of strontium
Atomic number 38
Atomic mass 87.62 g/mol
Specific gravity 2.64
Melting point 1050 K
Boiling point 1650 K
Isotopes 14
Pauling electronegativity 0.95
Appearance Soft, silver-yellowish metal
Other properties Strontium metal powder spontaneously ignites in the air.
Strontium volatile salts impart a bright red colour to flames.
INTRODUCTION
Properties and Uses of Strontium
Strontium, identified by the symbol Sr and atomic number
38, is an alkaline earth metal classified as a critical raw mate-
rial (CRM) since 2020 by the European Union (European
Commission, 2023). It is a commonly occurring element,
being the 15th most abundant element on Earth’s crust.
Strontium’s physical and chemical attributes (see Table 1)
closely resemble those of its neighbouring elements in the
periodic table, calcium, and barium (MacMillan et al.,
2000).
Strontium is a highly reactive element. Consequently,
it is never found in its pure state due to its rapid oxidation
upon exposure to air, leading to the formation of diverse
minerals. The most common strontium-bearing minerals
are celestine (SrSO4) and strontianite (SrCO3), the prin-
cipal sources of strontium through mining. More details
about the strontium-bearing minerals and their properties
are detailed in the following section.
The primary use for strontium in previous decades was
to produce a special glass for colour television cathode ray
tubes (CRTs) capable of preventing the emission of harmful
X-rays. However, with the rapid advancements in flat-panel
technologies for television and computer screens, CRTs
have become obsolete, resulting in a declining demand for
strontium carbonate in this sector. Nevertheless, strontium
is still utilised in the glass industry to improve the optical
and mechanical properties of materials, enhance transpar-
ency, increase refractive index, and reduce chromatic aber-
ration in optical lenses.
Nowadays, the main use of strontium compounds
is in pyrotechnics, drilling fluids and ceramic magnets
(European Commission, 2023 USGS, 2023). In pyrotech-
nics, strontium is used for the brilliant reds in fireworks and
warning flares and in some ‘glow-in-the-dark’ paints and
plastics. In the case of drilling fluids, strontium sulphate
and strontium carbonate are utilised as additives to enhance
drilling performance in the oil and gas sector, preventing the
formation of scales, such as calcium carbonate and barium
sulphate. Finally, strontium ferrite magnets (SrFe12O19) are
commonly used in small motors, loudspeakers, electronics
and toys because of their favourable magnetic properties
and low cost. Other uses of strontium include medicine,
where strontium compounds such as strontium ranelate
have been used for their potential to increase bone density
and reduce the risk of fractures in postmenopausal women
with osteoporosis.
Strontium Minerals
Strontium is primarily found in various minerals, with the
main ones being celestine (strontium sulphate, SrSO4),
strontianite (strontium carbonate, SrCO3), strontium fluo-
ride (SrF2), strontium molybdate (SrMoO4), and strontium
titanate (SrTiO3). These minerals are commonly located in
diverse geological formations, including sedimentary, igne-
ous, and metamorphic rocks.
Among these minerals, celestine stands out as the most
abundant and significant source of commercial strontium.
Although celestine is a relatively common mineral in sedi-
mentary environments, large economically exploitable
deposits are rare. World strontium reserves exceed one bil-
lion tons distributed between the USA, Argentina, China,
Iran, Mexico and Spain (Nesse, 2017). Strontianite is the
second most abundant strontium mineral, and it is utilised
for producing various strontium compounds like strontium
carbonate and strontium chloride. Although less common,
strontium fluoride, strontium molybdate, and strontium
titanate find industrial applications such as in glass, ceram-
ics, and pigments manufacturing.
Strontium is a relatively abundant element however, it
is not commonly found in large concentrations in a single
Table 1. Properties of strontium
Atomic number 38
Atomic mass 87.62 g/mol
Specific gravity 2.64
Melting point 1050 K
Boiling point 1650 K
Isotopes 14
Pauling electronegativity 0.95
Appearance Soft, silver-yellowish metal
Other properties Strontium metal powder spontaneously ignites in the air.
Strontium volatile salts impart a bright red colour to flames.