ANTIMONY TRIOXIDE
ANTIMONY TRIOXIDE
Antimony(III) oxide is the inorganic compound with the formula Sb2O3. Antimony trioxide is used as a synergist to enhance the activity of the halogenated flame retardant.
It is the most important commercial compound of antimony.
It is found in nature as the minerals valentinite and senarmontite.
Like most polymeric oxides, Sb2O3 dissolves in aqueous solutions with hydrolysis.
Production and properties
Global production of antimony(III) oxide in 2012 was 130,000 tonnes, an increase from 112,600 tonnes in 2002.
China produces the largest share followed by US/Mexico, Europe, Japan and South Africa and other countries (2%).
As of 2010, antimony(III) oxide was produced at four sites in EU27.
It is produced via two routes, re-volatilizing of crude antimony(III) oxide and by oxidation of antimony metal.
Oxidation of antimony metal dominates in Europe. Several processes for the production of crude antimony(III) oxide or metallic antimony from virgin material.
The choice of process depends on the composition of the ore and other factors.
Typical steps include mining, crushing and grinding of ore, sometimes followed by froth flotation and separation of the metal using pyrometallurgical processes (smelting or roasting) or in a few cases (e.g. when the ore is rich in precious metals) by hydrometallurgical processes.
These steps do not take place in the EU but closer to the mining location.
Re-volatilizing of crude antimony(III) oxide
Step 1) Crude stibnite is oxidized to crude antimony(III) oxide using furnaces operating at approximately 500 to 1,000 °C.
The reaction is the following:
2 Sb2S3 + 9 O2 → 2 Sb2O3 + 6 SO2
Step 2) The crude antimony(III) oxide is purified by sublimation.
Oxidation of antimony metal
Antimony metal is oxidized to antimony(III) oxide in furnaces.
The reaction is exothermic.
Antimony(III) oxide is formed through sublimation and recovered in bag filters.
The size of the formed particles is controlled by process conditions in furnace and gas flow. The reaction can be schematically described by:
4 Sb + 3 O2 → 2 Sb2O3
Properties
Antimony(III) oxide is an amphoteric oxide, it dissolves in aqueous sodium hydroxide solution to give the meta-antimonite NaSbO2, which can be isolated as the trihydrate.
Antimony(III) oxide also dissolves in concentrated mineral acids to give the corresponding salts, which hydrolyzes upon dilution with water.
With nitric acid, the trioxide is oxidized to antimony(V) oxide.
When heated with carbon, the oxide is reduced to antimony metal.
With other reducing agents such as sodium borohydride or lithium aluminium hydride, the unstable and very toxic gas stibine is produced.
When heated with potassium bitartrate, a complex salt potassium antimony tartrate, KSb(OH)2•C4H2O6 is formed.
Structure
The structure of Sb2O3 depends on the temperature of the sample.
Dimeric Sb4O6 is the high temperature (1560 °C) gas.
Sb4O6 molecules are bicyclic cages, similar to the related oxideof phosphorus(III), phosphorus trioxide.
The cage structure is retained in a solid that crystallizes in a cubic habit.
The Sb-O distance is 197.7 pm and the O-Sb-O angle of 95.6°.
This form exists in nature as the mineral senarmontite.
Above 606 °C, the more stable form is orthorhombic, consisting of pairs of -Sb-O-Sb-O- chains that are linked by oxide bridges between the Sb centers.
This form exists in nature as the mineral valentinite.
IUPAC name: Antimony(III) oxide
Other names: Antimony sesquioxide
Antimonous oxide
Flowers of Antimony
Identifiers
CAS Number: 1309-64-4
antimony trioxide
appropriate for use as a flame retardant synergist used in combination with a halogen compound.
Many materials utilize its flame retardant properties including plastics, rubber,paints, paper, textiles and electronics.
Antimony trioxide is appropriate for use in polypropylene (PP), polyethylene (PE), ethylene propylene diene M-class rubber (EPDM), polyvinyl chloride (PVC), high impact polystyrene (HIPS), acrylonitrile butadiene styrene (ABS), polyurethanes, phenolics, epoxies, and many others.
Other applications of antimony trioxide include a clarifying agent for glass, an opacifier for porcelain and enamel, and a white pigment
Antimony trioxide is formed by reacting antimony trichloride (SbCl3) with water.
It is used in combination with some brominated flame retardants, and might also be used in conjunction with zinc borate, both within and outside the United States on commercial furniture, draperies, wall coverings, and carpets.
It is also used in enamels, glasses, rubber, plastics, adhesives, textiles, paper, and as a paint pigment.
Antimony Trioxide
Antimony trioxide, also known as antimony oxide or Sb2O3, is the most widely produced compound of elemental antimony.
The nations that produce the most antimony trioxide are China,
South Africa, Bolivia, Russia, Tajikistan, and Kyrgyzstan.
Typical applications for antimony trioxide include flame retardant synergist for use in plastics, rubber, paints, paper, textiles, and electronics; polyethylene terephthalate polymerization catalyst; a clarifying agent for glass; an opacifier for porcelain and enamel; and a white pigment for paint.
When used as a flame retardant, antimony trioxide is often used in combination with halogenated compounds.
Antimony trioxide is used as a synergist to enhance the activity of the halogenated flame retardant.
In the absence of antimony trioxide about twice as much halogenated compound would be needed to reach the same level of flame retardancy.
Antimony trioxide (Antimony oxide)
CAS Registry Number 1309-64-4
What is it?
Antimony trioxide is an industrial chemical and also occurs naturally in the environment.
How is it used?
In Canada, antimony trioxide is primarily used in combination with other compounds to provide flame retardant properties.
Flame retardants used in household items such as mattress covers, furniture and carpets may contain antimony trioxide.
Antimony trioxide is also used in the manufacturing of a plastic material known as polyethylene terephthalate (PET).
Antimony trioxide (Antimony oxide)
CAS Registry Number 1309-64-4
What is it?
Antimony trioxide is an industrial chemical and also occurs naturally in the environment.
How is it used?
In Canada, antimony trioxide is primarily used in combination with other compounds to provide flame retardant properties.
Flame retardants used in household items such as mattress covers, furniture and carpets may contain antimony trioxide.
Antimony trioxide is also used in the manufacturing of a plastic material known as polyethylene terephthalate (PET).
Sodium Antimonate
Sodium antimonate [15593-75-6], Na3SbO4, another antimony synergist of commercial importance, has an antimony content of 61–63 wt % and a bulk density of 39.4–46.4 kg/m3.
It is made by oxidizing antimony trioxide using sodium nitrate and caustic.
It is a white powder and has a pH of around 9–11 when dissolved in water.
Sodium antimonate contains less antimony than either antimony trioxide or pentoxide and is thus less effective.
However, its unique pH and low refractive index makes the antimonate the most desirable synergist for polymers that hydrolyze when processed with acidic additives or in polymers for which deep color tones are specified.
Antimony Oxide as a Primary Flame Retardant
Antimony oxide behaves as a condensed-phase flame retardant in cellulosic materials.
It can be applied by impregnating a fabric with a soluble antimony salt followed by a second treatment that precipitates antimony oxide in the fibers.
When the treated fabric is exposed to a flame, the oxide reacts with the hydroxyl groups of the cellulose (qv) causing them to decompose endothermically.
The decomposition products, water and char, cool the flame reactions while slowing the production and volatilization of flammable decomposition products.
Antimony Pentoxide
The second most widely used antimony synergist is antimony pentoxide [1313-60-9], Sb2O5, produced by the oxidation of the trioxide using either a peroxide or nitric acid.
Antimony pentoxide is available as a nonpigmenting colloidal suspension in either water or organic media or as an agglomerated powder.
It is insoluble in water, but soluble in hot concentrated acids. Properties of this unique flame retardant synergist are listed in Table.
Properties of Antimony Pentoxide and Sodium Antimonate
Property Sb2O5 Na3SbO4
particle size, µm 0.03 1–2
surface area, m2/gm 50
specific gravity 4.0 4.8
surface activity weakly acidic basic
refractive index, n20D 1.7 1.75
Submicrometer antimony pentoxide is primarily used to impart flame retardancy to fibers and fabrics.
It can be added to the molten or dissolved polymer prior to forming the fiber.
The antimony in this form can easily pass through the spinnerets without clogging the openings, whereas standard grades of antimony trioxide would rapidly clog the openings and necessitate frequent shutdowns for cleaning.
The submicrometer antimony pentoxide is also more evenly dispersed in the fiber, resulting in better physical properties.
Powdered antimony pentoxide is used primarily in plastics.
Stabilizers used to prevent the particles from growing are caustic, and can react with the halogen in the formulation.
This can result in color formation and a lower flame-retarding efficiency of the system.
Antimony pentoxide is priced about two to three times higher than the trioxide.
However, because it is more efficient than the trioxide, the pentoxide is at least cost-equivalent
Flame Retardant Mechanism of Antimony Trioxide
Antimony trioxide itself has no flame retardant function, however, when it is used together with halogenated compounds, the synergistic effect of the mixture creates the flame retardant properties.
Antimony trioxide reacts with halogenated compound and creates the chemical compounds, which generate the flame retardant function, through the following process.
Stop action of thermal de-composite chain reaction under gas phase (Radical trap effect)
Sealing action against oxygen under gas phase (Air sealing effect)
The formation of carbonaceous char under the solid phase (Air sealing and adiabatic effect)
Synergetic effect of antimony trioxide on the flame retardant and mechanical properties of polymer composites for consumer electronics applications
Antimony trioxides are used as synergists to increase the activity of halogenated flame retardants by hindering the chain reaction of the flame gas phase through stepwise release of the halogenated radicals.
Antimony trioxide (ATO) is commonly used as a co-synergist with halogenated flame retardants to enhance their effectiveness.
Recent comprehensive genotoxicity studies and a critical review by the European Commission have indicated that, contrary to the indications of earlier less well authenticated studies, antimony trioxide is not a genotoxic carcinogen.
No adverse health effects are expected from antimony trioxide, although there remains some uncertainty on a possible cancer hazard arising from inhalation of particles, where better data on particular exposure is required.
However, in most cases, exposure is probably minor compared with exposure to antimony trioxide from other sources in the domestic and urban environment.
Brominated organic compounds and antimony trioxide traditionally used in molding compounds as flame retardants are known to have deleterious impacts on the environment.
Brominated flame retardants (BFRs) are also referred to as halogenated flame retardants due to the presence of bromine (Br−), which is considered a halogen.
Halogens are nonmetal elements from Group 17 in the new periodic table including fluorine, chlorine, bromine, iodine, and astatine.
The other substance of concern in conventional flame-retardant systems is antimony trioxide.
Antimony trioxides are used as synergists to increase the activity of halogenated flame retardants by hindering the chain reaction of the flame gas phase through stepwise release of the halogenated radicals
Antimony trioxide
Diantimony trioxide
Translated names
antimon-trioxid (hu)
antimona trioksīds (lv)
Antimonitrioksidi (fi)
antimonov trioksid (hr)
antimontrioksid (no)
Antimontrioksiid (et)
antimontrioxid (da)
diantimonov trioksid (sl)
diantimontrioksid (no)
diantimontrioxid (da)
diantimoontrioxide (nl)
oxid antimonitý (cs)
stibio trioksidas (lt)
tlenek antymonawy (pl)
tlenek antymonu(III) (pl)
triossido di diantimonio (it)
trioxide de antimoniu (ro)
trioxyde d’antimoine (fr)
tritlenek antymonu (pl)
trióxido de diantimonio (es)
trióxido de diantimónio (pt)
τριοξείδιο του διαντιμόνιου τριοξείδιο του aντιμονίου (el)
антимонов триоксид (bg)
CAS names
Antimony oxide (Sb2O3)
IUPAC names
(stibanyloxy)stibanediol
anitimony troxide
antimoniy trioxide
Registration dossier
Antimony
Registration dossier
Antimony (III) oxide
Antimony oxide
Antimony Trioxite
antimony trisuphide
C&L Inventory
antimony(3+) oxide
Antimony(III) oxide
diamtimony trioxide
diantimony trioxid
Diantimony trioxide_049
Diantimony trioxide_068
diantimony-trioxide-
Dioxodistiboxane
oxo(oxostibanyloxy)stibane
Oxo(oxostibanyloxy)stibane / antimony(3+); oxygen(2-)
oxostibanyl stibinate
Sb2O3
Trade names
Antimonio triossido
Antimony Trioxide TMS®-HP
ATO
Dust-free antimony trioxide
flame retardant masterbatch
Timonox® Blue Star
Antimony Compounds
Antimony Trioxide
Approximately 20,000 metric tons of antimony trioxide [1309-64-4] (commonly referred to as antimony oxide), Sb2O3, was used in the United States in 1990 to impart flame retardancy to plastics .
Although antimony trioxide is found in nature, it is too impure to be used.
Flame-retardant grades of antimony oxides are manufactured from either antimony metal or the sulfide ore by oxidation in air at 600–800°C.
The particle size and chemical reactivity is determined by the processing conditions, enabling the production of several different grades.
The physical properties of various grades are listed in Table.
Antimony trioxide is from 99.0–99.9 wt % Sb2O3.
The remainder consists of 0.4–0.01 wt % arsenic; 0.4–0.01, lead; 0.1–0.0001, iron; 0.005–0.0001, nickel; and 0.01–0.0001,sulfates.
It is insoluble in water and the loss on drying at 110°C is 0.1 wt % max.
Antimony trioxide has been used as a white pigment since ancient times.
The pigmentation from antimony oxide in plastics can be controlled and adjusted by the judicious selection of a Sb2O3 grade having a specific particle size.
The product with the smallest particle size and the narrowest particle-size range imparts the whitest color and highest opacity.
Translucent plastics can be made by using low tint grades with relatively large particles.
Antimony Oxide as a Primary Flame Retardant
Antimony oxide behaves as a condensed-phase flame retardant in cellulosic materials.
It can be applied by impregnating a fabric with a soluble antimony salt followed by a second treatment that precipitates antimony oxide in the fibers.
When the treated fabric is exposed to a flame, the oxide reacts with the hydroxyl groups of the cellulose (qv) causing them to decompose endothermically.
The decomposition products, water and char, cool the flame reactions while slowing the production and volatilization of flammable decomposition products.
Antimony Pentoxide
The second most widely used antimony synergist is antimony pentoxide [1313-60-9], Sb2O5, produced by the oxidation of the trioxide using either a peroxide or nitric acid.
Antimony pentoxide is available as a nonpigmenting colloidal suspension in either water or organic media or as an agglomerated powder.
It is insoluble in water, but soluble in hot concentrated acids
Sodium Antimonate
Sodium antimonate [15593-75-6], Na3SbO4, another antimony synergist of commercial importance, has an antimony content of 61–63 wt % and a bulk density of 39.4–46.4 kg/m3.
Properties are given in Table 2. It is made by oxidizing antimony trioxide using sodium nitrate and caustic.
It is a white powder and has a pH of around 9–11 when dissolved in water.
Sodium antimonate contains less antimony than either antimony trioxide or pentoxide and is thus less effective.
However, its unique pH and low refractive index makes the antimonate the most desirable synergist for polymers that hydrolyze when processed with acidic additives or in polymers for which deep color tones are specified
Antimony Trioxide
Antimony trioxide, also known as antimony oxide or Sb2O3, is the most widely produced compound of elemental antimony.
The nations that produce the most antimony trioxide are China, South Africa, Bolivia, Russia, Tajikistan, and Kyrgyzstan.
Typical applications for antimony trioxide include flame retardant synergist for use in plastics, rubber, paints, paper, textiles, and electronics; polyethylene terephthalate polymerization catalyst; a clarifying agent for glass; an opacifier for porcelain and enamel; and a white pigment for paint.
When used as a flame retardant, antimony trioxide is often used in combination with halogenated compounds.
Antimony trioxide is used as a synergist to enhance the activity of the halogenated flame retardant.
In the absence of antimony trioxide about twice as much halogenated compound would be needed to reach the same level of flame retardancy.
Antimony(III) oxide is the inorganic compound with the formula Sb2O3.
Antimony(III) oxide is the most important commercial compound of antimony.
Antimony(III) oxide is found in nature as the minerals valentinite and senarmontite.
Like most polymeric oxides, Sb2O3 dissolves in aqueous solutions with hydrolysis.
A mixed arsenic-antimony oxide occurs in the nature as the very rare mineral stibioclaudetite.
1 Antimony Compounds
The antimony compounds used for flame retardancy include antimony
trioxide, antimony pentoxide and antimony-metal compounds. In 1990 in
the United States alone, the use of antimony trioxide amounted to 20 000
metric tons just for the flame retardancy of plastics. Antimony oxide is
readily found in nature but in very impure form. This is not suitable for
direct use as flame retardant, so antimony oxide is often rather produced from antimony metal.
There are therefore many different grades of antimony oxide that can be used for flame retardants
Antimony oxide with a small particle size will for example give a polymer with a high opacity and white colour whereas the larger particle sizes produce translucent polymers.
Although particle size affects pigmentation,it does not appear to affect the flame retardant efficiency.
The price for antimony oxide is quite high, depending on the purity.
With cotton textiles, antimony oxide is usually applied by impregnating the fabric with a water soluble antimony solution, followed. by secondary treatment (such as evaporation) that deposits the oxide on the fibres.
When the treated sample is exposed to a flame, the fibres decompose endothermically.
The decomposition products, apart from the volatile components, are water and char, and this reduces the combustion temperature of the flame (Touval, 1993).
The second most widely used antimony compound d for flame retardancy is
antimony pentoxide (See Table 8). Unlike the trioxide, the pentoxide does not cause a pigmenting effect on the treated polymer.
Furthermore, the average particle size for a typical commercial pentoxide is 0.03 /-lm, which causes a more even distribution throughout the polymer.
This implies a less drastic change in the polymer properties, and overall better flame retardancy.
Antimony pentoxide is however priced two to three times higher than the trioxide
The antimony flame retardants follow the mechanism of the formation of antimony chloride with an oxychloride as a highly reactive intermediate.
The antimony oxide reacts with the halogen containing compound forming highly volatile antimony oxychloride (Touval, 1993).
The antimony oxychloride is a very reactive intermediate that forms antimony trichloride through several reactions (Touval, 1993).
By means of the above reactions, antimony helps to quickly move the halogen into the gas phase, where it acts as an effective flame retardant.
Antimony oxide was found not to be a carcinogenic nor to pose a risk to the environment.
Some antimony products do however contain trace amounts of arsenic, so caution should nevertheless be taken during handling (Touval, 1993).
Key Words: Polymer flammability; material flammability; antimony fire retardant; bromine fire retardant; halogen fire retardant; fire retardant; kinetic model; flame inhibition; antimony trihydride; antimony tribromide
Antimony trioxide, together with organochlorine and organobromine compounds, is a widely used fire retardant additive in commodity polymers.
This application represents the largest commercial use of antimony (as well as of bromine).
The fire retardant action is believed to occur in the gas phase (Fenimore and Martin, 1966b, Fenimore and Martin, 1966a, Fenimore and Jones,
1966, Fenimore and Martin, 1972). Yet in spite of the long use and many studies of antimonybromine systems as fire retardants, for example there have been few fundamental studies describing the gas phase inhibition mechanism by antimony and its synergetic effect when combined with chlorine or bromine.
Unlike most other gas-phase active flame inhibitors, there are no kinetic or thermodynamic models for antimony flame inhibition, and consequently, there has been no simulation or analysis of those system
Antimony-bromine gas-phase synergism:
The combination of antimony trioxide with a chlorinated or brominated species in polymers is empirically known to be a synergistic fire retardant mixture for polymers.
Hence, it is of interest to explore if the present model shows any synergism in the gas-phase inhibition mechanism of a system with both Sb and Br present
Antimony—A Flame Fighter
Antimony is a brittle, silvery-white semimetal that conducts heat poorly. The chemical compound antimony trioxide (Sb2O3) is widely used in plastics, rubbers, paints, and textiles, including industrial safety suits and some children’s clothing, to make them resistant to the spread of flames.
Also, sodium antimonate (NaSbO3) is used during manufacturing of high-quality glass, which is found in cellular phones.
Humans have known about stibnite (Sb2S3), a lead-gray antimony sulfide mineral, since ancient times.
Egyptians used powdered stibnite in black eye makeup to create their signature look.
Pedanius Dioscorides, a 1st century A.D. Greek physician, recommended stibnite for skin ailments.
French and German doctors in the 17th century prescribed antimony-containing mixtures to induce vomiting.
Antimony was later recognized to be an intense skin irritant and a lethal toxin, particularly when swallowed.
In the 11th century, the word antimonium was used by medieval scholar Constantinus Africanus, but antimony metal was not isolated until the 16th century by Vannoccio Biringuccio, an Italian metallurgist. In the early 18th century, chemist Jons Jakob Berzelius chose the periodic symbol for antimony (Sb) based on stibium, which is the Latin name for stibnite.
How Do We Use Antimony?
Most of the world’s antimony is used (as antimony trioxide) in flame-retardant materials; powdered trioxide is chemically inserted or physically blended into many different materials, including textiles.
Although antimony trioxide is not a flame retardant by itself, when it is combined with halogens (such as bromine) in polymers, the resulting mixture suppresses, reduces, and delays the spread of flames.
Alloys of antimony and lead provide enhanced electrical properties to batteries as well as increased hardness to ammunition. Battery electrodes coated As part of a broad mission to conduct research and provide information on nonfuel mineral resources, the U.S. Geological Survey (USGS) supports science
to understand
• How and where antimony resources form and concentrate in Earth’s crust
• How antimony resources interact with the environment to affect human and ecosystem health
• Trends in the supply of and demand for antimony in the domestic and international markets
• Where undiscovered antimony resources might be found
Many cellular phones use antimony-bearing batteries. Research for lithium-ion battery replacements led to the development of antimony nanocrystals for future use in high energy density batteries.
Ammunition made with antimony-lead alloys is capable of penetrating some armor.
Antimony is used during the production of plastics, including polyethylene terephthalate or PET, used for common items like soda bottles.
Sodium antimonate is used during the manufacturing of highquality glass to remove bubbles and trace iron and impart a sun-resistant property.
Where Does Antimony Come From?
Although antimony occurs worldwide and in many types of deposits, just two deposit types contain the majority of the global antimony supply.
Carbonate-replacement deposits (for example,Xikuangshan, Hunan Province, China) and gold-antimony epithermal deposits (for example, Yellow Pine, Idaho, U.S.) provide 80 percent of the world’s antimony.
The carbonate-replacement deposit type accounts for 60 percent of the world’s antimony and is the main source of commercially consumed antimony.
Stibnite, the most common antimony mineral, occurs in veins hosted in carbonate rocks such as limestone.
Nearly pure stibnite may occur in lenses tens of meters long, making for very rich ore.
Gold-antimony epithermal deposits are the second most common type and contain 20 percent of the world’s antimony.
In these deposits, ore occurs in veins but in lower overall concentrations than carbonate-replacement type.
Veins connect to each other in three-dimensional networks to form a low-grade, high-tonnage deposit that can be mined in open pits.
Host rocks commonly include shale, limestone, quartzite, granite, calc-silicate rocks, and various volcanic rocks.
The remaining 20 percent of antimony comes from magmatic polymetallic veins and hot spring deposits