| Identification | More | [Name]
Tellurium | [CAS]
13494-80-9 | [Synonyms]
TELLOY
tellur
urium L
TELLURIUM
TELLERIUM
Tellunium
nci-c60117
TellurStcke
Tellurium (Te)
aurumparadoxum
tellur(polish)
Tellurium shot
tellurium atom
Tellurium, 99+%
TelluriumchunkN
TELLURIUM METAL
TelluriumpiecesN
Tellurium powder
TELLURIUM BROKEN
TELLURIUM, PIECES
TELLURIUM 99.999%
Tellurium element
Te Target 99.99%
tellureelementaire
Tellurium granules
TELLURIUM STANDARD
metallumproblematum
Tellurium Nanoprisms
MERCURIC CHLORIDE TS
TelluriumpowderNmesh
TELLURIUM AA STANDARD
Telluriumpowder(99.9%)
TELLURIUM METAL POWDER
TELLURIUM ICP STANDARD
Tellurium broken ingot
Tellurium powder, 99.8%
Telluriumpowder(99.999%)
TELLURIUM: 99.5%, POWDER
Tellurium,99.999%,pieces
Tellurium, Lump 99.999+%
Tellurium, ingot, broken
Tellurium, Powder 22 Mesh
tellurium for high purity
TELLURIUM, INGOT, 99.999%
Telluriumingotbrokenpieces
TELLURIUM, PIECES, 99.999%
Tellurium, reagent, powder
TELLURIUM ICP/DCP STANDARD
TelluriuM, 200 Mesh, Powder
Tellurium, powder, 200 mesh
TelluriuM Metal 99,9 % Min.
TELLURIUM STANDARD SOLUTION
Tellurium(Metal)Powder99.9%
Tellurium solution 1000 ppm
TELLURIUM, -40 MESH, 99.997%
Tellurium lump (metals basis)
Tellurium solution 10 000 ppm
Telluriumbrokeningot(99.999%)
Tellurium ISO 9001：2015 REACH
Tellurium lumps/pieces 99.999%
Tellurium pieces, Zone refined
Telluriumbrokeningot(99.9999%)
TELLURIUM, SHOT, 1-2MM, 99.999%
Tellurium, reagent, powder, 99+%
Tellurium broken ingot (99.99+%)
Tellurium,99.8%,powder, 200 mesh
TELLURIUM, AAS STANDARD SOLUTION
Tellurium, 99+%, reagent, powder
TELLURIUM SINGLE ELEMENT STANDARD
Tellurium broken ingot (99.9996%)
Tellurium, Powder 22 Mesh 99.999%
TELLURIUM POWDER: 99.999%, 30 MESH
Tellurium, Ingot, Broken 99.9999+%
TELLURIUM PLASMA EMISSION STANDARD
Tellurium lump, 99% (metals basis)
Tellurium, 99.80%, powder, 200 mesh
TELLURIUM, PLASMA STANDARD SOLUTION
Tellurium, powder, 200 mesh, 99.80%
TELLURIUM, POWDER, -200 MESH, 99.8%
TELLURIUM ATOMIC ABSORPTION STANDARD
TELLURIUM AA SINGLE ELEMENT STANDARD
TelluriuM, reagent, powder, 99+% 10GR
TelluriuM Metal 99% Min., 99,96% Min.
TelluriuM, powder, (trace Metal basis)
TelluriuM, powder, 200 Mesh, 99.8% 25GR
Tellurium, lump, zone refined, 99.999+%
TELLURIUM ICP STANDARD TRACEABLE TO SRM
TELLURIUM SINGLE ELEMENT PLASMA STANDARD
TELLURIUM, GRANULES, -5+50 MESH, 99.99%
TelluriuM, powder, 200 Mesh, 99.8% 100GR
Tellurium lump, Typically 12mm (0.47 in.)
TELLURIUM SINGLE ELEMENT STANDARD ICP-AES
Tellurium and compounds (as Te) total dust
Tellurium, ingot, broken pieces, 99.9999+%
TELLURIUM, INGOT, BROKEN PEICES, 99.9999+%
Tellurium lump, 99.999% trace metals basis
TelluriuM pieces, 99.999% trace Metals basis
TELLURIUM ATOMIC ABSORPTION STANDARD SOLUTION
Tellurium, AAS standard solution, Te 1000μg/mL
Tellurium, plasma standard solution, Specpure?
Tellurium, plasma standard solution, Te 10μg/mL
TELLURIUM PLASMA EMISSION SPECTROSCOPY STANDARD
TelluriuM, 99.999%, (trace Metal basis), powder
Tellurium standard solution, 1 mg/ml Te in 2% KOH
Tellurium, plasma standard solution, Te 1000μg/mL
Tellurium shot, 1-2 mm, 99.999% trace metals basis
Tellurium broken ingot, 99.9999% trace metals basis
Tellurium, plasma standard solution, Te 10,000μg/mL
Tellurium atomic absorption standard solution,powder
TelluriuM powder, -200 Mesh, 99.8% trace Metals basis
TelluriuM powder, -30 Mesh, 99.997% trace Metals basis
Tellurium powder, -60 mesh, 99.999% trace metals basis
Tellurium shot, 2-5mm dia., 99.9999% trace metals basis
TelluriuM, 99.8%, (trace Metal basis), powder, -200 Mesh
Tellurium standard solution,for AAS,1 mg/ml Te in 2% KOH
Tellurium, plasma standard solution, Specpure, Te 10g/ml
TelluriuM granular, -5-+50 Mesh, 99.99% trace Metals basis
Tellurium standard solution, 1 mg/ml Te in 2% KOH, for AAS
Tellurium ICP Standard@1000 μg/mL in 20% Hydrochloric acid
Tellurium ICP Standard@10000 μg/mL in 40% Hydrochloric acid
Tellurium, AAS standard solution, Specpure(R), Te 1000μg/ml
Tellurium ICP-MS Standard@100 μg/mL in 10% Hydrochloric acid
Tellurium broken ingot, Puratronic, 99.9999+% (metals basis)
Tellurium ICP-MS Standard@1000 μg/mL in 20% Hydrochloric acid
Tellurium ICP-MS Standard@10000 μg/mL in 20% Hydrochloric acid
Tellurium, plasma standard solution, Specpure(R), Te 1000μg/ml
Tellurium broken ingot, Puratronic(R), 99.9999+% (metals basis)
Tellurium powder, -22 mesh, Puratronic, 99.9985% (metals basis)
Tellurium ingot/button, ^=38mm (2.5in) dia x 6mm (0.24in) thick
Tellurium shot, 1-3mm (0.04-0.08in) dia, 99.9999% (metals basis)
Tellurium, plasma standard solution, Specpure(R), Te 10,000μg/ml
Tellurium shot, 2-5mm (0.08-0.20in) dia, 99.9999% (metals basis)
Tellurium powder, -18+60 mesh, Puratronic, 99.999% (metals basis)
Tellurium shot, spherical, 1-2mm, low oxide, 99.999% (metals basis)
Tellurium powder, -18+60 mesh, Puratronic(R), 99.999% (metals basis)
Tellurium ingot/button, &ap:38mm (1.5 in.) dia. x 6mm (0.24 in.) thick
TELLURIUM, 99.995%TELLURIUM, 99.995%TELLURIUM, 99.995%TELLURIUM, 99.995%
TelluriuM ingot/button, ^=38MM (1.5in) dia x 6MM (0.24in) thick, 99.9% (Metals basis) | [EINECS(EC#)]
236-813-4 | [Molecular Formula]
Te | [MDL Number]
MFCD00134062 | [Molecular Weight]
127.6 | [MOL File]
13494-80-9.mol |
| Chemical Properties | Back Directory | [Definition]
A nonmetallic element with
many properties similar to selenium and sulfur.
Atomic number 52; group VIA of the period table;
aw 127.60; valences of 2, 4, 6; eight stable isotopes. | [Appearance]
Silvery-white, lustrous solid with metal
characteristics. Soluble in sulfuric
acid, nitric acid, potassium hydroxide, and potassium
cyanide solutions; insoluble in water. Imparts
garlic-like odor to breath, can be depilatory. It is a ptype
semiconductor a | [Melting point ]
450 °C(lit.)
| [Boiling point ]
990 °C(lit.)
| [density ]
6.24 g/mL at 25 °C(lit.)
| [vapor pressure ]
0Pa at 25℃ | [storage temp. ]
Sealed in dry,Room Temperature | [solubility ]
insoluble in H2O, benzene, CS2 | [form ]
shot
| [color ]
Silver-white | [Specific Gravity]
6.24 | [Resistivity]
5.8-33 μΩ-cm, 20°C | [Water Solubility ]
insoluble H2O, benzene, CS2 [MER06] | [Merck ]
13,9201 | [Exposure limits]
TLV-TWA 0.1 mg (Te)/m3 (ACGIH)
PEL-TWA: 0.1 mg (Te)/m3 (OSHA)
TWA 0.1 mg (Te)/m3 (NIOSH)
. | [InChIKey]
VTLHPSMQDDEFRU-UHFFFAOYSA-N | [History]
Discovered by Muller von Reichenstein in 1782; named
by Klaproth, who isolated it in 1798. Tellurium is occasionally
found native, but is more often found as the telluride of
gold (calaverite), and combined with other metals. It is recovered
commercially from the anode muds produced during
the electrolytic refining of blister copper. The U.S., Canada,
Peru, and Japan are the largest producers of the element.
Crystalline tellurium has a silvery-white appearance, and
when pure exhibits a metallic luster. It is brittle and easily pulverized.
Amorphous tellurium is formed by precipitating tellurium
from a solution of telluric or tellurous acid. Whether
this form is truly amorphous, or made of minute crystals, is
open to question. Tellurium is a p-type semiconductor, and
shows greater conductivity in certain directions, depending
on alignment of the atoms. Its conductivity increases slightly
with exposure to light. It can be doped with silver, copper,
gold, tin, or other elements. In air, tellurium burns with a
greenish-blue flame, forming the dioxide. Molten tellurium
corrodes iron, copper, and stainless steel. Tellurium and its
compounds are probably toxic and should be handled with
care. Workmen exposed to as little as 0.01 mg/m3 of air, or
less, develop “tellurium breath,” which has a garlic-like odor.
Forty-two isotopes and isomers of tellurium are known, with
atomic masses ranging from 106 to 138. Natural tellurium
consists of eight isotopes, two of which are radioactive with
very long half-lives. Tellurium improves the machinability of
copper and stainless steel, and its addition to lead decreases
the corrosive action of sulfuric acid on lead and improves its
strength and hardness. Tellurium catalysts are used in the oxidation
of organic compounds and are used in hydrogenation
and halogenation reactions. Tellurium is also used in electronic
and semiconductor devices. It is also used as a basic
ingredient in blasting caps, and is added to cast iron for chill
control. Tellurium is used in ceramics. Bismuth telluride has
been used in thermoelectric devices. Tellurium costs about
50￠/g, with a purity of about 99.5%. The metal with a purity
of 99.9999% costs about $5/g. | [CAS DataBase Reference]
13494-80-9(CAS DataBase Reference) | [EPA Substance Registry System]
Tellurium (13494-80-9) |
| Hazard Information | Back Directory | [Chemical Properties]
Silvery-white, lustrous solid with metal
characteristics. Soluble in sulfuric
acid, nitric acid, potassium hydroxide, and potassium
cyanide solutions; insoluble in water. Imparts
garlic-like odor to breath, can be depilatory. It is a ptype
semiconductor and its conductivity is sensitive
to light exposure. | [Chemical Properties]
Tellurium is a grayish or silvery white, lustrous, crystalline, semimetallic element. It may exist in a hexagonal crystalline form or an amorphous powder. It is found in sulfide ores and is produced as a by-product of copper or bismuth refining. | [General Description]
Grayish-white, lustrous, brittle, crystalline solid; dark-gray to brown, amorphous powder with metallic characteristics. Used as a coloring agent in chinaware, porcelains, enamels, glass; producing black finish on silverware; semiconductor devices and research; manufacturing special alloys of marked electrical resistance. Improves mechanical properties of lead; powerful carbide stabilizer in cast iron, TELLURIUM(13494-80-9) vapor in "daylight" lamps, vulcanization of rubber. Blasting caps. Semiconductor research. | [Hazard]
(Metal and compounds as tellurium) Toxic
by inhalation. Halitosis. | [Reactivity Profile]
TELLURIUM is attacked by chlorine fluoride with incandescence. When tellurium and potassium are warmed in an atmosphere of hydrogen, combination occurs with incandescence [Mellor 11:40. 1946-47]. Burning tellurium produces toxic tellurium oxide gas. Avoid solid sodium, halogens, interhalogens, metals, hexalithium disilicide. Reacts with nitric acid; reacts with concentrated sulfuric acid forming a red solution. Dissolves in potassium hydroxide in the presence of air with formation of deep red solution; combines with halogens. Avoid antimony and chlorine trifluoride; chlorine trifluoride reacts vigorously with tellurium producing flame. Fluorine and tellurium react with incandescence. Lithium silicide attacks tellurium with incandescence. Reaction with zinc is accompanied by incandescence (same potential with cadmium, only hazard is less). A vigorous reaction results when liquid tellurium is poured over solid sodium [EPA, 1998]. | [Air & Water Reactions]
A finely divided suspension of elemental tellurium in air will explode. Insoluble in water. | [Health Hazard]
Causes central nervous system depression. Moderate skin and eye irritant. Tellurium is capable of doing harm within the body by replacing the essential element sulfur. | [Potential Exposure]
The primary use of tellurium is in the vulcanization of rubber and as an additive in ferritic steel production. It is also used as a carbide stabilizer in cast iron, a chemical catalyst; a coloring agent in glazes and glass; a thermocoupling material in refrigerating equipment; as an additive to selenium rectifiers; in alloys of lead, copper, steel, and tin for increased resistance to corrosion and stress, workability, machinability, and creep strength; and in certain culture media in bacteriology. Since tellurium is present in silver, copper, lead, and bismuth ores, exposure may occur during purification of these ores. | [Fire Hazard]
A finely divided suspension of elemental tellurium in air will explode. Burning tellurium produces toxic tellurium oxide gas. Avoid solid sodium, halogens, interhalogens, metals, hexalithium disilicide. Reacts with nitric acid; reacts with concentrated sulfuric acid forming a red solution. Dissolves in potassium hydroxide in the presence of air with formation of deep red solution; combines with halogens. Avoid antimony and chlorine trifluoride; chlorine trifluoride reacts vigorously with tellurium producing flame. Fluorine and tellurium react with incandescence. Lithium silicide attacks tellurium with incandescence. Reaction with zinc is accompanied by incandescence (same potential with cadmium, only hazard is less). A vigorous reaction results when liquid tellurium is poured over solid sodium. | [First aid]
If this chemical gets into the eyes, remove any contact lenses at once and irrigate immediately for at least 15 minutes, occasionally lifting upper and lower lids. Seek medical attention immediately. If this chemical contacts the skin, remove contaminated clothing and wash immediately with soap and water. Seek medical attention immediately. If this chemical has been inhaled, remove from exposure, begin rescue breathing (using universal precautions, including resuscitation mask) if breathing has stopped and CPR if heart action has stopped. Transfer promptly to a medical facility. When this chemical has been swallowed, get medical attention. Obtain authorization and/or further instructions from the local hospital for administration of an antidote or performance of other invasive procedures. Give a slurry of activated charcoal in water to drink. Seek medical attention. Give large quantities of water and inducevomiting. Do not make an unconscious person vomit. Medical observation is recommended for 24-48 hours after breathing overexposure, as pulmonary edema may be delayed. As first aid for pulmonary edema, a doctor or authorized paramedic may consider administering a drug or other inhalation therapy.
| [Shipping]
UN3288 Toxic solids, inorganic, n.o.s., Hazard Class: 6.1; Labels: 6.1-Poisonous materials, Technical Name Required. | [Incompatibilities]
Finely divided powder or dust may be flammable and explosive. Violent reaction with halogens, interhalogens, zinc and lithium silicide; with incandescence. Incompatible with oxidizers, cadmium; strong bases; chemically active metals; silver bromate; nitric acid. | [Description]
Tellurium is one of the rarest elements on earth similar to
selenium, and was discovered in Transylvania in 1782 by
Franz-Joseph Muller von Reichenstein. The name derived from
the Latin word for earth. Tellurium is occasionally found
naturally, more often as telluride of gold, calaverite. | [Physical properties]
Tellurium is a silver-white, brittle crystal with a metallic luster and has semiconductorcharacteristics. It is a metalloid that shares properties with both metals and nonmetals, andit has some properties similar to selenium and sulfur, located just above it in group 16 of theperiodic table.
There are two allotropic forms of tellurium: (1) the crystalline form that has a silvery metallicappearance and a density of 6.24 g/cm3, a melting point of 499.51°C, and a boiling point of988°C; and (2) the amorphous allotrope that is brown in color and has a density of 6.015g/cm3and ranges for the melting and boiling point temperatures similar to the crystalline form. | [Isotopes]
There are a total of 48 isotopes of tellurium. Eight of these are consideredstable. Three of the stable ones are actually radioactive but have such long half-livesthat they still contribute to the natural abundance of tellurium in the crust of the Earth.The isotope Te-123 (half-life of 6×10+14 years) contributes 0.89% of the total telluriumfound on Earth, Te-128 (half-life of 7.7×10+24 years) contributes 31.74% to the naturalabundance, and Te-130 (half-life of 0.79×10+21 years) contributes 34.08% to the telluriumin the Earth’s crust. The other five stable isotopes and the percentage of theirnatural abundance are as follows: Te-120 = 0.09%, Te-122 = 2.55%, Te-124 = 4.74%,Te-125 = 7.07%, and Te-126 = 18.84%. The other 40 isotopes are all radioactive withshort half-lives. | [Origin of Name]
The name “tellurium” is derived from the Latin word for Earth, tellus. | [Occurrence]
Tellurium is the 71st most abundant element on Earth. It makes up a small portion ofigneous rocks and is sometimes found as a free element, but is more often recovered fromseveral ores. Its major ores are sylvanite (AgAuTe4), also known as graphic tellurium, calaverite,sylvanite, and krennerite, all with the same general formula (AuTe2). Other minor ores arenagyagite, black tellurium, hessite, altaite, and coloradoite. In addition, it is recovered fromgold telluride (AuTe2). Significant quantities are also recovered from the anode “slime” of theelectrolytic refining process of copper production. | [Characteristics]
The pure form of tellurium burns with a blue flame and forms tellurium dioxide (TeO2).It is brittle and is a poor conductor of electricity. It reacts with the halogens of group 17, butnot with many metals. When it reacts with gold, it forms gold telluride. Tellurium is insolublein water but readily reacts with nitric acid to produce tellurous acid. If inhaled, it produces agarlic-like odor on one’s breath. | [Purification Methods]
Purify it by zone refining and repeated sublimation to an impurity of less than 1 part in 108 (except for surface contamination by TeO2). [Machol & Westrum J Am Chem Soc 80 2950 1958.] Tellurium is volatile at 500o/0.2mm. It has also been purified by electrode deposition [Mathers & Turner Trans Amer Electrochem Soc 54 293 1928]. | [Flammability and Explosibility]
Nonflammable | [Environmental Fate]
Metals are recalcitrant to degradation; therefore, no biodegradation studies have been performed on tellurium. No aquatic bioaccumulation data exist for tellurium; however, based on its density and low water solubility, it is unlikely to present a concern for bioaccumulation in the water column. No environmental monitoring data are available on the levels of tellurium in sediment or sediment-dwelling organisms. Therefore, it is unclear whether tellurium has the potential to bioaccumulate in this compartment. In humans, tellurium accumulates in the bones. Based on this, it may be assumed that tellurium has the potential to bioaccumulate in vertebrates. | [Toxicity evaluation]
Tellurium has a low toxicity in its elemental form, but dimethyltelluride
is formed in the body. Tellurium caused a highly
synchronous primary demyelination of peripheral nerves,
related to the inhibition of squalene epoxidase, which blocks
cholesterol synthesis. The sequence of metabolic events in
sciatic nerve following tellurium treatment initially involves
inhibition of the conversion of squalene to 2,3-epoxysqualene,
and this block in the cholesterol biosynthesis pathway results,
either directly or indirectly, in the inhibition of the synthesis of
myelin components and the breakdown of myelin. The efficacy
of garlic as a lipid-lowering agent has been recognized, but the
biochemical mechanisms underlying this action are currently
unknown. It is possible that organic tellurium compounds,
which are found in high concentration in fresh garlic buds, may
contribute to this action by inhibiting squalene epoxidase, the
penultimate enzyme in the synthetic pathway of cholesterol.
Weanling rats fed a diet rich in tellurium develop a demyelinating
polyneuropathy because of inhibition of this enzyme in
peripheral nerves. Chronic exposure to small amounts of
tellurium found in garlic might reduce endogenous cholesterol production through inhibition of hepatic squalene epoxidase
and so reduce cholesterol levels. Tellurium may also contribute
to the characteristic odor of garlic. |
| Safety Data | Back Directory | [Hazard Codes ]
T | [Risk Statements ]
R25:Toxic if swallowed. | [Safety Statements ]
S45:In case of accident or if you feel unwell, seek medical advice immediately (show label where possible) . | [RIDADR ]
UN 3288 6.1/PG 3
| [WGK Germany ]
3
| [RTECS ]
WY2625000
| [TSCA ]
Yes | [HazardClass ]
8 | [PackingGroup ]
III | [HS Code ]
28045000 | [Safety Profile]
Poison by ingestion and intratracheal routes. An experimental teratogen. Exposure causes nausea, vomiting, tremors, convulsions, respiratory arrest, central nervous system depression, and garlic odor to breath. Aerosols of tellurium, tellurium dioxide, and hydrogen telluride cause irritation of the respiratory system and may lead to the development of bronchitis and pneumonia. Experimental reproductive effects. Under the proper conditions it undergoes hazardous reactions with halogens (e.g., chlorine, fluorine), interhalogens (e.g., bromine pentafluoride, chlorine fluoride, chlorine trifluoride), metals (e.g., cadmium, potassium, sodium, platinum, tin, zinc), hexalithium disilicide, silver bromate, silver iodate. When heated to decomposition it emits toxic fumes of Te. See also TELLURIUM COMPOUNDS. | [Hazardous Substances Data]
13494-80-9(Hazardous Substances Data) | [Toxicity]
A member element of group IVa in the Periodic
Table with both metallic and non-metallic properties.
Tellurium compounds of biological interest include the elemental form, as well as compounds with valences of 12 (telluride), 14 (tellurite), and 16 (tellurate). Commercial
applications of tellurium include its use as a coloring agent
and as an alloy with other metals. Industrial hazards generally
involve the volatile forms including tellurium dioxide and
hydrogen telluride rather than the less toxic elemental form.
Exposure to potassium tellurite may also occur; this compound
is known to cause hemolysis of erythrocytes, probably via its
reduction product, telluride. Other non-nervous system effects
of exposure to tellurium compounds include weight loss, blue/
black discoloration of skin, and a characteristic garlic breath
odor. Animal models have clearly implicated tellurium in
induction of specific neuropathological findings. These include
its action as a teratogen in the induction of communicating
hydrocephalus (treated rats give rise to affected offspring),
lipofuscinosis, and peripheral neuropathy. | [IDLA]
25 mg Te/m3 |
| Questions And Answer | Back Directory | [Chemical Properties]
Tellurium is a heavy metal, which is processed as a grey powder. It has hexagonal, rhombohedral structure, a low water solubility and high relative density. The particle size ranges from 52.36 to 112.98 μm.
Tellurium is a silvery white metal in group 16 of the periodic table. It shares chemical and clinical properties with selenium(Amdur, 1947, 1958; Schroeder et al., 1967; Shie andDeeds, 1920). Telluriumis a semiconductor and may have multiple electron states (-2, 0, +2, +4, +6). It can react with hydrogen to form hydrogen telluride and with halogens. Tellurite (+2) and teleurate (+4) compounds are water soluble. Elemental tellurium burns, producing a blue flame and tellurium dioxide.
| [History]
The element was discovered by Muller von Reichenstein in 1782 while investigating a bluish-white ore of gold. The element was isolated from this ore by Klaproth in 1798, who suggested the name “tellurium” after the Latin word tellus, meaning earth. Tellurium occurs in nature only in minute quantities. It is found in small amounts in many sulfide deposits. One of the more common tellurium minerals is calaverite, AuTe2 , in which the metal is combined with gold. Some other tellurium minerals are altaite, PbTe; sylvanite, (Ag,Au)Te2; rickardite, Cu4Te3; tetradymite, Bi2Te2S; petzite, Ag3AuTe2 and coloradoite, HgTe. The metal is found in the native state and also in the form of its dioxide, tellurite, TeO2. The abundance of tellurium in the earth’s crust is estimated to be about 1 µg/kg.
| [Uses]
Small amounts of tellurium are added to stainless steel and copper to improve their machinability. It enhances the strength and hardness of lead and protects lead from the corrosive action of sulfuric acid. Tellurium also is a strong chilling agent in iron castings. It controls the chill and imparts a tough abrasion resistance to the surface.
Tellurium is a curing agent for natural and synthetic rubber. It improves mechanical properties of the rubber imparting resistance to heat and abrasion. Tellurium is a coloring agent in glass, ceramics, and enamels. Traces of tellurium incorporated into platinum catalysts make the catalytic hydrogenation of nitric oxide favorable to forming hydroxylamine. A major application of tellurium is in semiconductor research. Tellurides of lead and bismuth are used in thermoelectric devices for power generation and refrigeration.
| [Production Methods]
Tellurium is recovered from the anode slimes produced in electrolytic refining of copper. Other metals present in these slimes are gold, silver, and selenium, which are all recovered as by-products in the extraction of tellurium. Tellurium is leached with caustic soda solution and the leachate upon neutralization precipitates tellurium dioxide, TeO2, in crude and impure form. A part of tellurium remaining in the slimes can be recovered during extraction of gold and silver. In this gold and silver recovery process, tellurium incorporates into the soda slag obtained from roasting the slimes in a furnace. Soda slag is produced when leached with a solution of caustic soda. The liquor is neutralized to form a crude precipitate of tellurium dioxide.
Crude tellurium dioxide is dissolved in a strong solution of caustic soda to form sodium tellurite. Electrolysis of sodium tellurite solution deposits tellurium metal on the stainless steel cathode.
Also, the tellurium metal can be prepared by thermal reduction of dioxide. However, prior to reduction crude dioxide is refined by successive caustic leaching and neutralization steps mentioned above.
Refined tellurium contains traces of lead, copper, iron, selenium, and other impurities. Highly pure tellurium can be obtained either by distilling refined tellurium in vacuum or by the zone melting process. The last traces of selenium can be removed as hydride by treating molten tellurium with hydrogen.
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