Chemical Fact Sheet
Zinc
| Chemical Abstract Number (CAS #) | 7440-66-6 |
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| Synonyms | ASARCO-L-15; BLUE-POWDER; EMANAY-ZINC-DUST; GRANULAR-ZINC; JASAD; MERRILLITE; ZINC-DUST; ZINC-POWDER |
| Analytical Methods | 200.7 - 200.8 - 6010 - 6020 |
| Molecular Formula | Zn |
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Synopsis
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Zinc-(Ger. Zink, of obscure origin), Zn; at. wt. 65.39(2); at. no. 30, f.p. 419.527 deg C; b.p. 907 deg C; sp. gr. 7.133 (25 deg C); valence 2. Centuries before zinc was recognized as a distinct element, zinc ores were used for making brass. Tubal-Cain, seven generations from Adam, is mentioned as being an "instructor in every artificer in brass and iron." An alloy containing 87% zinc has been found in prehistoric ruins in Transylvania. Metallic zinc was produced in the 13th century A.D. in India by reducing calamine with organic substances such as wool. The metal was rediscovered in Europe by Marggraf in 1746, who showed that it could be obtained by reducing calamine with charcoal. The principal ores of zinc are sphalerite or blende (sulfide), smithsonite (carbonate), Calamine (silicate), and franklinite (zinc, manganese, iron oxide). Zinc can be obtained by roasting its ores to form the oxide and by reduction of the oxide with coal or carbon, with subsequent distillation of the metal. Other methods of extraction are possible. Naturally occurring zinc contains five stable isotopes. Twenty three other unstable isotopes and isomers are recognized. Zinc is a bluish-white, lustrous metal. It is brittle at ordinary temperatures but malleable at 100 to 150 deg C. It is a fair conductor of electricity, and burns in air at high red heat with evolution of white clouds of the oxide. The metal is employed to form numerous alloys with other metals. Brass, nickel silver, typewriter metal, commercial bronze, spring brass, German silver, soft solder, and aluminum solder are some of the more important alloys. Large quantities of zinc are used to produce die castings, used extensively by the automotive, electrical, and hardware industries. An alloy called Prestal(R), consisting of 78% zinc and 22% aluminum is reported to be almost as strong as steel but as easy to mold as plastic. It is said to be so plastic that it can be molded into form by relatively inexpensive die casts made of ceramics and cement. It exhibits superplasticity. Zinc is also extensively used to galvanize other metals such as iron to prevent corrosion. Neither zinc nor zirconium is ferromagnetic; but ZrZn2 exhibits ferromagnetism at temperatures below 35 K. Zinc oxide is a unique and very useful material to modem civilization. It is widely used in the manufacture of paints, rubber products, cosmetics, pharmaceuticals, floor coverings, plastics, printing inks, soap, storage batteries, textiles, electrical equipment, and other products. It has unusual electrical, thermal, optical, and solid-state properties that have not yet been fully investigated. Lithopone, a mixture of zinc sulfide and barium sulfate, is an important pigment. Zinc sulfide is used in making luminous dials, X-ray and TV screens, and fluorescent lights. The chloride and chromate are also important compounds. Zinc is an essential element in the growth of human beings and animals. Tests show that zinc-deficient animals require 50% more food to gain the same weight as an animal supplied with sufficient zinc. Zinc is not considered to be toxic, but when freshly formed ZnO is inhaled a disorder known as the oxide shakes or zinc chills sometimes occurs. It is recommended that where zinc oxide is encountered good ventilation be provided. The commercial price of zinc was roughly 50 cents/lb ($1.10 kg) in January 1996. Zinc metal with a purity of 99.9999% is priced at about 50 cents/g. |
| Use | ZINC BASE ALLOYS USED FOR DIE CASTING; GALVANIZING AGENT; COMPONENT IN BRASS, BRONZE ALLOYS, ROLLED ZINC PRODUCTS, LIGHT METAL ALLOY & IN WET BATTERIES; CHEM INT FOR ZINC OXIDE; DESILVERIZING AGENT FOR LEAD PROTECTIVE COATING FOR METALS TO PREVENT CORROSION; FOR ELECTRICAL APPARATUS, ESP HOUSEHOLD UTENSILS, CASTINGS, PRINTING PLATES, BUILDING MATERIALS, RAILROAD CAR LININGS, AUTOMOTIVE EQUIPMENT; REDUCING AGENT IN ORG CHEM; DEOXIDIZING BRONZE; EXTRACTING GOLD BY CYANIDE PROCESS, PURIFYING FATS FOR SOAPS; BLEACHING BONE GLUE; MFR SODIUM HYDROSULFITE, INSULIN ZINC SALTS; REAGENT IN ANAL CHEM. As negative electrode in alkaline cell electrode. In bearings. In electroplating. In gold dental alloys. In magnesium alloys. In metallic driers. In mixed-metal stabilizers. In paper defoxing. Use in cadmium recovery. Use in cooling towers as anodic inhibitors. Zinc oxide: zinc is the most commonly used phosphor powder in vacuum fluorescence displays. Finely divided zinc incorporated in grease can be coated on the interior surfaces of an aluminum connector to provide lower initial contact resistance and better long term resistance stability. As galvanizing coating on steel wires and tapes for buried and submarine cables. |
| Consumption Patterns | ZINC-BASE ALLOY, 38%; GALVANIZING, 38%; BRASS PRODUCTS, 15%; ROLLED ZINC, 3%; ZINC OXIDE, 3%; OTHER, 3% Construction materials, 45%; Transportation, 25%; Machinery, 10%; Electrical, 10%; other, 10% (1985) |
| Apparent Color | BLUISH-WHITE, LUSTROUS METAL, DISTORTED HEXAGONAL CLOSEPACKED STRUCTURE |
| Boiling Point | 908 DEG C |
| Melting Point | 419.5 DEG C |
| Molecular Weight | 65.38 |
| Density | 7.14 AT 25 DEG C |
| Sensitivity Data | A human skin irritant. |
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Chemical and Physical Properties |
MOHS HARDNESS 2.5; WHEN HEATED TO 100-150 DEG C BECOMES MALLEABLE, AT 210 DEG C BRITTLE & PULVERIZABLE; BURNS IN AIR WITH BLUISH-GREEN FLAME; SLOWLY ATTACKED BY SULFURIC ACID OR HYDROCHLORIC ACID, OXIDIZING AGENTS OR METAL IONS; FORMS ZINCATES WITH ALKALI HYDROXIDES; NATURAL ISOTOPES ARE 64 (48.89%), 66 (27.81%), 68 (18.57%), 67 (4.11%), & 70 (0.62%) FAIR CONDUCTOR OF ELECTRICITY Zinc has standard electrode potential of +0.761 & is electropositive to most structural metals except aluminum & manganese Electrical conductivity: 28.3% IACS; Electrical resistivity: 5.9 uohm-cm; thermal conductivity: 122.958 W/m-deg K; tensile strength: 283-324 MPa at room temp |
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Environmental Impact |
The bioconcentration factor in edible portions of Crassostrea Virginia (adult oyster) is 16,700. The bioconcentration factor in edible portions of Mya arenaria (soft-shell clam) is 85. Bioconcentration factors in edible portions of Mytilus edulis (mussel) is 500. About 50 times higher zinc concn (5000 mg/kg) was found in soil close to smelter compared with control area. |
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Environmental Fate |
OCCURS IN SMITHSONITE OR ZINC SPAR, SPHALTERITE OR ZINC BLENDE, ZINCITE, WILLEMITE, FRANKLINITE OR GAHNITE. Occurs naturally as calamine, smithsonite & wurtzite. The average concentration in the earth's crust is estimated to be 40 mg/kg. During blasting & crushing of ore moderate losses of zinc to the atmosphere occur. Treatment of the crush by means of wet flotation may result in emissions into water. During smelting there are often large emissions into air, which will result in cadmium emissions. The total emission of zinc into the atmosphere during smelting in USA during 1969 has been estimated at 50000 tons. Significant zinc contamination of soil is only seen in vicinity of point sources. Dairy products: 4.9 ppm (avg concn in prepared food composites) Meat & poultry: 32.0 ppm (avg concn in prepared food composites) Grain & cereal produts: 9.0 ppm (avg concn in prepared food composites) Potatoes: 5.2 ppm (avg concn in prepared food composites) Leafy vegetables: 2.7 ppm (avg concn in prepared food composites) Legume vegetables: 7.6 ppm (avg concn in prepared food composites) Root vegetables: 2.3 ppm (avg concn in prepared food composites) Garden fruits: 2.1 ppm (avg concn in prepared food composites) Fruits: 2.4 ppm (avg concn in prepared food composites) Oils, fats, shortening: 4.1 ppm (avg concn in prepared food composites) Sugar & adjuncts: 3.0 ppm (avg concn in prepared food composites) Beverages: 0.5 ppm (avg concn in prepared food composites) Meat, fish, and poultry on an average contained 24.5 mg/kg of zinc, whereas grains (and cereal products) and potatoes only provided 8 and 6 mg/kg, respectively. The normal levels of zinc range from 10-100 mg/kg in most crops and pastures. Fish: 32.0 ppm (avg concn in prepared food composites) AVERAGE NORMAL LEVELS OF ZINC IN CATTLE ARE: LIVER, 135 PPM; KIDNEYS, 80 PPM; FECES, 200 PPM, (ALL DRY MATTER) AND SERUM 0.14 PPM. IN ANIMALS SUFFERING FROM ZINC POISONING CORRESPONDING VALUES ARE: LIVER, 2000 PPM; KIDNEYS, 670 PPM; FECES, 3740 PPM; AND SERUM, 0.515 PPM. Human milk contains about 3 mg/l. Exposure to zinc fumes, particularly zinc oxide is a potential risk wherever zinc oxide is produced, for example in zinc smelting, manufacture of zinc oxide and powder, production of brass and melting of galvanized iron. Zinc poisoning is mostly accidental from the intake of pesticides, inadvertent therapeutic use of heavy doses of zinc salts, or drinking of acidic juices or brews made in galvanized iron utensils. The average daily intake of zinc in different areas was summarized and arrived at a value in the order of 5-22 mg/day. IT WAS CONCLUDED THAT METAL FUME FEVER WOULD NOT RESULT FROM CONCN BELOW 15 MG/CU M, & THIS CONCN WAS RECOMMENDED TLV FOR NUMBER OF YEARS. MORE RECENT EXPERIENCE INDICATE CONCN IN NON-FERROUS FOUNDRIES PRODUCE ZINC CHILLS & HAVE BEEN REPORTED BELOW 5 MG/CU M. Of several effects resulting from industrial exposure to zinc, that of zinc fume fever from freshly formed zinc oxide fume is most commonly described & best documented. In survey of 102 brass foundry workers, 20% had attacks of "brass foundryman's ague" on avg of once/wk, 13% once/mo, 17% once/yr, 11% twice/wk, 14% twice/mo, 6% twice/yr, 2% 3 times/mo, 1% 3 times/yr & about 10% 4 times/yr. The attacks among 88% of workers occurred only during winter mo when ventilation was inadequate, but 12% had attacks regardless of season. Zinc oxide level that caused the attacks was not determined. Human milk contains about 3 mg/l. Therapeutic or normal blood level: 0.068-0.136 mg%, 0.68-1.36 ug/ml. The highest concn of zinc appears in the choroid of the eye, spermatozoa, hair, nails. In plasma, most zinc is protein bound, predominantly to albumin alpha 2-macroglobulin, and transferrin. Zinc concentrations in tissues of 10 human males (mean age 43 yr) who suffered sudden death. Zinc was detected in all 10 tissues (brain, heart, kidney cortex, liver, lung, muscle, pancreas, small intestine, spleen, and stomach). Highest levels were in the liver, muscle, and kidney. Results were presented graphically and no values were given. In human liver there was a positive relationship between the concentration of zinc and the amount of metallothionein in the tissue. |
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Disposal |
At the time of review, criteria for land treatment or burial (sanitary landfill) disposal practices are subject to significant revision. Prior to implementing land disposal of waste residue (including waste sludge), consult with environmental regulatory agencies for guidance on acceptable disposal practices. Chemical Treatability of Zinc; Concentration Process: Activated carbon; Chemical Classification: Metals; Scale of Study: Full scale continuous flow; Type of Wastewater Used: (not stated); Results of Study: 81% reduction; 124 ppb effluent concentration; Carbon used as advanced treatment of biologically and chemically treated wastewater. Plant capacity 0.66 cu m/sec. Data presented for two time periods. Chemical Treatability of Zinc; Concentration Process: Activated carbon; Chemical Classification: Metals; Scale of Study: Full scale continuous flow; Type of Wastewater Used: (not stated); Results of Study: 61% reduction; 162 ppb effluent concentration; Carbon used as advanced treatment of biologically and chemically treated wastewater. Plant capacity 0.66 cu m/sec. Data presented for two time periods. Chemical Treatability of Zinc; Concentration Process: Miscellaneous sorbents; Chemical Classification: Metals; Scale of Study: Literature review; Type of Wastewater Used: Unknown; Results of Study: Final concentration reduced to 0.1 ppb; SiO2 + CaO slags used. The proprietary sulfex process (Permutit Co) has been applied to zinc wastes. The process involves addition of ferrous sulfide, which gradually releases sulfide to precipitate the zinc. In the case where zinc removal is the only consideration and recovery is not warranted, removal by precipitation can be accomplished by standard pH adjustment through lime addition, precipitation and flocculation, and sedimentation, employing standard waste treatment equipment. Operating data for existing chemical precipitation units indicate that levels of 1 mg/l or less of zinc are readily obtainable with lime precipitation, although assurance of consistent removal of precipitated zinc to lower levels from the effluent stream may require filtration. Reuse & landfill: Reclaim for salvage or reuse. Unsalvageable waste may be buried in an approved landfill. Max concn in effluent to sewer or stream is 1.0 ppm. |
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Atmosphere |
Zinc oxide fumes may also be produced secondary to torch welding and cutting of zinc containing or galvanized materials. These processes yield a dispersion into the atmosphere of zinc oxide particles of about 1 um. |
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