Bismuth

Description

Bismuth is a white, crystalline, brittle metal with a pinkish tinge. Bismuth is the most diamagnetic of all metals, and the thermal conductivity is lower than any metal. It occurs naturally in the metallic state and in minerals such as bismite. The most important ores are bismuthinite or bismuth glance and bismite, and countries such as Peru, Japan, Mexico, Bolivia, and Canada are major producers of bismuth. It is found as crystals in the sulphide ores of nickel, cobalt, silver, and tin.

Bismuth is mainly produced as a by-product from lead and copper smelting. It is insoluble in hot or cold water. Bismuth explodes if mixed with chloric or perchloric acid. Molten bismuth explodes and bismuth powder glows red-hot on contact with concentrated nitric acid. It is flammable in powder form. Bismuth is used in the manufacture of low melting solders and fusible alloys; as key components of thermoelectric safety appliances, such as automatic shut-offs for gas and electric water-heating systems and safety plugs in compressed gas cylinders; in the production of shot and shotguns; in pharmaceuticals; in the manufacturing of acrylonitrile; and as the starting material for synthetic fibres and rubbers. Bismuth oxychloride is sometimes used in cosmetics. Also bismuth subnitrate and bismuth subcarbonate are used in medicine. Bismuth subsalicylate is used as an anti-diarrhoeal and as a treatment of some other gastrointestinal diseases.

Chemical properties

Bismuth is the fifth element in the nitrogen group, and its properties are the most metal-likeof the five. Elemental bismuth is a heavy, brittle, hard metal that can be polished to a brightgray-white coat with a pinkish hue. It is not found in this state very often because it is more likelyto be combined with other metals and minerals, such as tin, lead, iron and cadmium. These aremixtures with low melting points, making them useful in fire-detection devices.
When heated in air, bismuth burns with a blue flame, giving off clouds of its yellow oxide.Bismuth’s melting point is 271.40°C, its boiling point is 1,564°C, and its density is 9.807 g/cm³.

Physical properties

Bismuth has unusually low toxicity for a heavy metal. Bismuth is stable to both dry and moist air at ordinary temperatures. When red hot, it reacts with water to make bismuth(III) oxide. Bismuth forms trivalent and pentavalent compounds. The trivalent compounds are more common. Many of its chemical properties are similar to those of As and Sb, although they are less toxic than derivatives of those lighter elements. At elevated temperatures, the vapors of the metal combine rapidly with oxygen, forming the yellow trioxide, Bi₂O₃.

Physical properties

In the transmittance and reflectance spectra of BeO, the main peak of the reflectance is located at 730 cm-1 and the small peak is located at 1050 cm^-1. The fundamental frequency of the lattice absorption is ν0=700±10 cm^-1, according to the reflectance analysis.

Isotopes

There are a total of 59 radioactive isotopes for bismuth, ranging in half-livesfrom a few milliseconds to thousands of years. At one time it was thought that there wasjust one stable isotope (Bi-209), but it was later found that Bi-209 is radioactive witha half-life of 19,000,000,000,000,000,000 years. Such a long half-life means that Bi-209 has not completely disintegrated and is still found in nature, and is thus consideredstable. In this case, Bi-209 makes up 100% of Bismuth’s natural abundance.

Origin of Name

Bismuth was known and used by the ancient alchemists along with other metals both for chemical reactions and for medical purposes. The name comes from the German bismu, which had been changed from wismu, meaning “white.”

Occurrence

Bismuth is the 70th most abundant element, and it is widely spread over the Earth’s crust, butin very small amounts. There are no major concentrated sources. It occurs both in the free elementalstate and in several ores. The major ore, bismuthinite (B₂S₃), is found in South America.
The United States gets most of its bismuth as a by-product from smelting ores of lead,silver, copper, and gold. It is also recovered from the refining of tin and tungsten ores.

History

In early times bismuth was confused with tin and lead. Claude Geoffroy the Younger showed it to be distinct from lead in 1753. It is a white crystalline, brittle metal with a pinkish tinge. It occurs native. The most important ores are bismuthinite or bismuth glance (Bi2S3) and bismite (Bi2O3). Peru, Japan, Mexico, Bolivia, and Canada are major bismuth producers. Much of the bismuth produced in the U.S. is obtained as a by-product in refining lead, copper, tin, silver, and gold ores. Bismuth is the most diamagnetic of all metals, and the thermal conductivity is lower than any metal, except mercury. It has a high electrical resistance, and has the highest Hall effect of any metal (i.e., greatest increase in electrical resistance when placed in a magnetic field). “Bismanol” is a permanent magnet of high coercive force, made of MnBi, by the U.S. Naval Surface Weapons Center. Bismuth expands 3.32% on solidification. This property makes bismuth alloys particularly suited to the making of sharp castings of objects subject to damage by high temperatures. With other metals such as tin, cadmium, etc., bismuth forms low-melting alloys that are extensively used for safety devices in fire detection and extinguishing systems. Bismuth is used in producing malleable irons and is finding use as a catalyst for making acrylic fibers. When bismuth is heated in air it burns with a blue flame, forming yellow fumes of the oxide. The metal is also used as a thermocouple material, and has found application as a carrier for U235 or U233 fuel in atomic reactors. Its soluble salts are characterized by forming insoluble basic salts on the addition of water, a property sometimes used in detection work. Bismuth oxychloride is used extensively in cosmetics. Bismuth subnitrate and subcarbonate are used in medicine. Natural bismuth contains only one isotope 209Bi. Forty-four isotopes and isomers of bismuth are known. Bismuth metal (99.5%) costs about $250/kg.

Characteristics

Bismuth is more resistant to electrical current in its solid state than it is in its liquid form.Its thermal conductivity is the lowest of all metals, except mercury. Even though it is considereda metal-like element, it is a very poor conductor of heat and electricity.
Bismuth has a characteristic similar to water. It expands when changing from the liquidphase to the solid phase. This factor makes it useful as an alloy in metals that are used to fillmolds, given that it will expand to the cast’s dimensions.

The Uses of Bismuth

Bismuth is used to make the drugs such as Pepto-Bismol for upset stomachs and diarrheaand in medicine to treat intestinal infections. Bismuth is used in the cosmetics industry toprovide the “shine” for lipsticks, eye shadow, and other products.
It is added to steel and other metals as an alloy to make the metals easier to roll, press, pullinto wires, and turn on a lathe. It is also used in the semiconductor industry and to makepermanent magnets.
Bismuth is similar to antimony in that it expands from the molten liquid state to the solidstate. This property makes it an excellent material to pour into molds and can produce finedetails in whatever is being molded, such as metallic printing type and similar fine castings.

The Uses of Bismuth

Several bismuth compounds have been used medicinally. Some are used for gastrointestinal distress (Pepto-Bismol contains bismuth subsalicylate). Others are used as salves and, in rare cases, for treatment of parasites. In the past, bismuth was also used to treat syphilis and malaria.
Commercially, bismuth is also used in the manufacture of permanent magnets, semiconductors, and thermoelectric materials; as a catalyst in making acrylonitrile; and as an additive to improve the machinability of steels and other metals.
Bismuth is also frequently used in cosmetics, generally nail polish and lipstick.

Definition

A brittle pinkish metallic element belonging to group 15 (formerly VA) of the periodic table. It occurs native and in the ores Bi₂S₃ and Bi₂O₃. The element does not react with oxygen or water under normal temperatures. It can be dissolved by concentrated nitric acid. Bismuth is widely used in alloys, especially low-melting alloys. The element has the property of expanding when it solidifies. Compounds of bismuth are used in cosmetics and medicines.

Definition

bismuth: Symbol Bi. A white crystallinemetal with a pinkish tinge belongingto group 15 (formerly VB) ofthe periodic table; a.n. 83; r.a.m.208.98; r.d. 9.78; m.p. 271.3°C; b.p.1560°C. The most important ores arebismuthinite (Bi₂S₃) and bismite(Bi₂S₃). Peru, Japan, Mexico, Bolivia,and Canada are major producers. Themetal is extracted by carbon reductionof its oxide. Bismuth is the mostdiamagnetic of all metals and itsthermal conductivity is lower thanany metal except mercury. The metalhas a high electrical resistance and ahigh Hall effect when placed in magneticfields. It is used to make lowmelting-point casting alloys with tinand cadmium. These alloys expandon solidification to give clear replicationof intricate features. It is alsoused to make thermally activatedsafety devices for fire-detection andsprinkler systems. More recent applicationsinclude its use as a catalystfor making acrylic fibres, as a constituentof malleable iron, as a carrierof uranium–235 fuel in nuclearreactors, and as a specialized thermocouplematerial. Bismuth compounds(when lead-free) are used for cosmeticsand medical preparations. It is attackedby oxidizing acids, steam (athigh temperatures), and by moisthalogens. It burns in air with a blueflame to produce yellow oxide fumes.C. G. Junine first demonstrated that itwas different from lead in 1753.

Production Methods

Bismuth is obtained as a by-product in smelting and refining of lead, copper or tungsten ores. The metal is partially volatilized when the ore is smelted at the high temperature. Separation from copper is achieved by electrolytic refining, bismuth accumulating in the anode slimes with lead, arsenic, antimony, tellurium, and other metal impurities. All throughout the smelting and refining operations bismuth accompanies lead. It finally is removed from lead by Betterton-Kroll or Betts processes. The Betterton-Kroll process involves the addition of calcium-lead alloy or magnesium metal to lead slime, thus converting bismuth to high-melting bismuthides of calcium or magnesium, Ca3Bi2 or Mg3Bi2, respectively. These bismuthides liquate from the bath and are separated as dross. Bismuth dross is then melted in kettles forming Bi7Mg6K9 which liquates to the top of the bath and is removed from the molten lead. Treatments with caustic soda finally produce the high quality bismuth.
In a modified process, potassium substitutes for calcium to form Bi7Mg₆Ca₉ which liquates to the top of the bath and is removed from the molten lead. The Betts process is based on electrolytic refining using a solution of lead fluorosilicate and fluorosilicic acid. While lead is deposited on the cathode, bismuth goes to the anode where it is collected with other impurity metals. It is then filtered, dried, smelted, and further refined, depending on the purity desired. Impurities are removed by adding molten caustic and zinc, and finally by chlorination.
Bismuth may be obtained from other ores, too. The recovery process however, depends primarily on the chemical nature of the ores. For example, the sulfide ore requires smelting, carbon reduction, and the addition of iron (to decompose any bismuth sulfide present). Oxide ores, on the other hand, are treated with hydrochloric acid to leach bismuth from the mineral. The bismuth chloride solution is then diluted with water to precipitate bismuth oxy-chloride. The precipitate is roasted with lime and charcoal. Satisfactory recovery of the metal from its carbonate ore may be achieved by both the above techniques.
Bismuth is sold in the form of rod, lump, powder, and wire.

General Description

All foils are mounted on a permanent support which cannot be removed without damaging the foil.

Hazard

Bismuth is flammable as a powder. The halogen compounds of bismuth are toxic wheninhaled or ingested. Some of the salts of bismuth can cause metallic poisoning in a mannersimilar to mercury and lead.
At the beginning of the twentieth century, before penicillin, bismuth compounds wereused to treat some venereal diseases. However, the treatment was generally unsuccessful.

Health Hazard

Exposures to bismuth salts are associated primarily by ingestion. Bismuth is known to cause adverse health effects. The symptoms include, but are not limited to, irritation of the eyes, skin, respiratory tract, lungs, foul breath, metallic taste, and gingivitis. On ingestion, bismuth causes nausea, loss of appetite, weight, malaise, albuminuria, diarrhea, skin reactions, stomatitis, headache, fever, sleeplessness, depression, rheumatic pain, and a black line may form on gums in the mouth due to deposition of bismuth sulfi de. Prolonged exposure to bismuth causes mild but deleterious effects on the kidneys and high concentrations of bismuth result in fatalities. Occupational exposures to bismuth occur during the manufacture of cosmetics, industrial chemicals, and pharmaceuticals. Acute exposure with over dosage of bismuth-containing drugs causes anorexia, nausea, vomiting, abdominal pain, and possibly a dry mouth and thirst. Bismuth also causes neurotoxicity. Bismuth pentafl uoride is highly toxic and causes irritation to the skin, eyes, and respiratory tract, while bismuth subnitrate causes blurred vision.

Flammability and Explosibility

Non flammable

Industrial uses

Bismuth (symbol Bi) is a brittle, crystallinemetal with a high metallic luster with a distinctivepinkish tinge. The metal is easily cast butnot readily formed by working. Within a narrowrange of temperature, around 225°C, it can beextruded. Its crystal structure is rhombohedral.It is one of the few metals that expand onsolidification; the expansion is 3.3%. The thermalconductivity of bismuth is lower than thatof any metal, with the exception of mercury.Bismuth is the most diamagnetic of all metals(mass susceptibility of –1.35×10⁶). It showsthe greatest Hall effect (increase in resistanceunder influence of a magnetic field). It also hasa low capture cross section for thermal neutrons(0.034 barn).
Bismuth is playing an important role innuclear research. Its high density gives it excellentshielding properties for gamma rays whileits low thermal neutron capture cross sectionallows the neutrons to pass through. For investigationsin which it is desired to irradiateobjects, i.e., animals, with neutrons but protectthem from gamma rays, castings of bismuth areused as neutron windows in nuclear reactors.Bismuth has been proposed as a solventcoolantsystem for nuclear power reactors. Thebismuth dissolves sufficient uranium so that,when the solvent and solute are pumpedthrough a moderator (graphite), criticality isreached and fission takes place. The heat generatedfrom the fission reaction raises the temperatureof the bismuth. The heated bismuth isthen pumped to conventional heat exchangersproducing the steam power required for eventualconversion to electricity.

Potential Exposure

Bismuth is used as a constituent of tempering baths for steel alloys; in low Freezing/Melting point alloys which expand on cooling; in aluminum and steel alloys to increase machinability; and in printing type metal. Bismuth compounds are found primarily in pharmaceuticals as antiseptics, antacids, antiluetics, and as a medicament in the treatment of acute angina. They are also used as a contrast medium in roentgenoscopy and in cosmetics. For the general population the total intake from food is 5 20 μg with much smaller amounts contributed by air and water.

First aid

If this chemical gets into the eyes, remove anycontact lenses at once and irrigate immediately for at least15 min, occasionally lifting upper and lower lids. Seek medical attention immediately. If this chemical contacts theskin, remove contaminated clothing and wash immediatelywith soap and water. Seek medical attention immediately. Ifthis chemical has been inhaled, remove from exposure,begin rescue breathing (using universal precautions, including resuscitation mask) if breathing has stopped and CPR ifheart action has stopped. Transfer promptly to a medicalfacility. When this chemical has been swallowed, get medical attention. Give large quantities of water and inducevomiting. Do not make an unconscious person vomit.
Note: Dimercaptol (BAL) brings good results in the treatment of bismuth poisoning if given early. Other measuresinclude atropine and meperidine to relieve gastrointestinaldiscomfort

Carcinogenicity

An old lifetime study with rats fed 2% bismuth subcarbonate (BSC) in the diet did not show an increase of tumors or a decrease of survival.

Environmental Fate

The mechanism by which bismuth produces toxicity has not been identified. Interaction with thiol compounds has been proposed as a primary mechanism.

storage

Color Code—Green: General storage may be used.

Shipping

UN3089 Metal powders, flammable, n.o.s., Hazard Class: 4.1; Labels: 4.1—Flammable solid.

Purification Methods

Melt it in an atmosphere of dry helium, then filter through dry Pyrex wool to remove any bismuth oxide present [Mayer et al. J Phys Chem 64 238 1960].

Toxicity evaluation

In aerated water, bismuth oxidizes; however, in an anaerobic aqueous environment, bismuth is unaffected. Similarly, in the atmosphere, bismuth is unaffected unless condensation or deposition of water occurs.
Due to the inability for air and water to affect bismuth under most circumstances, bismuth tends to persist until wet or dry deposition, and therefore long-range transport is possible and likely.

Structure and conformation

The space lattice of Bi belongs to the trigonal system, and its arsenic type structure has lattice constants of a=0.4736 nm, Bi–Bi=0.310 nm, α=57°16', and u=0.474.

Incompatibilities

Finely divided powder is highly flammable. Reacts with strong acids and strong oxidizers, chlorine, fused ammonium nitrates, iodine pentafluoride, and nitrosyl fluoride.

Waste Disposal

Dissolve in a minimum amount of concentrated HCl. Dilute with water until precipitate is formed. Redissolve in HCl. Then saturate with H2S. Filter, wash, dry and return to supplier.