About Metals

The mining of copper started in Cyprus in the Roman Era. From there emerged the original name of the metal which was Cyprium that meant ‘metal of Cyprus’. Later this name was shortened and the metal was renamed ‘Cuprum’. This also gives Copper its symbol ‘Cu’.

It is estimated that the discovery of copper took place around 9000 B.C. in the Middle East. It is one of the first metals discovered by man and ever since it has played an important part in the growth and development of mankind. Archaeological discoveries have shown that copper has been utilized by several civilizations for making tools, handicrafts, utensils, weapons and other household articles.

Copper is one of the most durable metals available. The condition of the remnants of the copper articles from archaeological discoveries demonstrates the metal’s durability and its resistance to corrosion. Copper has been ascertained to be the finest metal for supplying water. Copper pipes have been in use since many years and continue to evolve. The modern form of copper piping is strong yet light and highly resistant to corrosion. Copper piping serves all types of residential, commercial and industrial buildings.

Copper is ductile metal that is a very good conductor of heat and electricity and hence is used in many electrical applications. Pure copper is malleable and can be stretched easily. The exposed surface of the metal is in reddish-orange colour.

Chile in South America is the largest producer of Copper in the World. Copper has a wide range of application in Electrical, Transport, Aerospace, Heat exchangers, telecommunications, utensils and glass industry. It is an exceptional conductor of heat and electricity and hence finds wide usage in the power generation, transmission, and electrical applications.

Today, around 400 copper and copper-alloys are used in various applications. They are classified under categories such as copper, high copper alloy, bronze, copper-nickel, copper-nickel-zinc, brass, leaded copper and special alloys. These alloys are created to best suit the design applications. They are some of the basic metals that are used in domestic and industrial sectors.

Name of the Metal: Copper, named after Cyprus

Discovery: Middle East in 9000 B.C. era

Symbol: Cu

Number: 29

Element Category: Transition Metal

Group, Period, Block: 11, 4, d

Electron Configuration: [Ar] 3d10 4s1

Standard Atomic Weight: 63.546(3)

Physical Properties:

Phase: Solid

Density (near r.t.):

Liquid density atm.p.:

Melting point: 1357.77 K, 1084.62 °C, 1984.32 °F

Boiling Point: 2835 K, 2562 °C, 4643 °F

Heat of Fusion:

Heat of vaporization:

Molar heat capacity:

Vapour Pressure:

Atomic Properties:

            Oxidation states: +1, +2, +3, +4?(mildly basic oxide)

            Electronegativity: 1.90 (Pauling scale)

            Atomic Radius: 128 pm

            Covalent Radius: 132±4 pm

            Van der Waals radius: 140 pm

COPPER – A METAL USED THROUGH THE AGES

The humans from very early civilizations have used copper. That shows that it is one of the first metals extracted by the human civilizations. Since then, it has made many important contributions to the improvement and sustenance of our society. The initial use of copper was limited to making coins and ornaments. It is estimated that copper was first used in making these articles about 8000 B.C. ago. As the civilizations developed, more uses of the metals were discovered. About 5500 B.C. ago, man started using copper to make tools and weapons. Later it was discovered that copper when alloyed with tin produced bronze. This discovery marks the beginning of Bronze Age at 3000 B.C.

Copper is a malleable metal. It can be stretched and moulded very easily. It is resistant to corrosion and is a good conductor of heat and electricity. For these reasons, copper has been an important metal since ages. Even today, it continues to be one of the best metals for a wide range of domestic, technological and industrial applications. 

HOW DO WE USE COPPER TODAY?

Today, copper is used in a wide variety of industrial and domestic application. Construction, electronic product manufacturing, industrial machinery production, transport vehicle production and power generation and transmission are some of the sectors in which copper plays an integral role.

Electrical

It is estimated that about 65 per cent of the copper produced finds utility in electrical applications. Copper is an exceptional conductor of heat and electricity and hence is greatly used in power generation and transmission and electrical applications. For power generation and transmission, copper is used in manufacturing generators, motors, transformers, cables and busbars. They ensure safety and efficiency of these equipments. In Electrical applications, copper is used to provide circuitry and wiring for electrical equipments.

Copper has also found an increased use in semiconductor manufacturing industry. It is used in making silicon chips and rotors. Copper helps in making these equipments more efficient by making them operate faster with lesser power consumption.

Construction

About 25 per cent of the World’s copper is used in construction activities. Copper forms an important part in plumbing, cladding and roofing. Copper is durable and light. These properties help the builders to erect structures that require minimum maintenance and last very long.

Transport

Transport is another leading industry that finds substantial copper application. Around 7 per cent of the World’s refined copper is used in trains, cars, trucks and trams. Copper wires are used in these systems to ensure current flow from the battery to equipments such as lights, GPS, chargers and other systems in the vehicle. Copper is the vital component in radiators, wiring, motors, bearings of transport vehicles and brakes. On an average, a car 1.5 km of copper wiring and 20 kg to 45 kg of copper is used in its manufacturing.

Other

The very early usage of copper was limited to making coins and ornaments. Even now, many countries use copper to make coins. However, over the years new uses of the metal have been identified. Using copper in frequently touched surface is a relatively newfound use of the metal. Copper has antimicrobial properties that reduce the likelihood of transfer of germs and allergies. This has made it apt for usage in frequently touched surface such as doorknobs.

Industries in heating and cooling systems, appliances and telecommunication cables have high usage of copper materials.

USEFUL PROPERTIES OF COPPER

Copper has exceptional alloying properties. Copper when alloyed with zinc produces brass and when alloyed with tin produces bronze. It is also alloyed with nickel. Depending upon the composition of these alloys, they have desired characteristics that are then used in specialized applications. For instance, a defined composition of copper-nickel alloy is used in manufacturing of ship’s hull. This is to ensure that the hull does not corrode in sea water and reduction in adhesion to marine life. Use of copper in manufacturing hull also increases its fuel efficiency. Brass is used in musical instruments, as it is easy to stretch and mould and has good acoustic properties.

OCCURRENCE

Copper is created in the Stars and forms a part of other celestial bodies. It is found in Earth’s crust at a concentration level of 50 ppm. It is either found as native copper or in mineral oxides. Some of these oxides are copper sulphides chalcocite and chalcopyrite, copper oxide mineral cuprite, and copper carbonates azurite and malachite. Largest mass of elemental copper was found in Keweenaw peninsula in Michigan in United States. It weighed around 420 tonnes.

TYPES OF COPPER DEPOSITS

Copper is present in many forms depending under the conditions that it is deposited. The metal finds occurrence in many different minerals. The most abundant and cost-effective copper mineral is Chalcopyrite.

Broad classification of copper can be done on the basis of how the deposits are formed. About two-third of world’s copper comes from Porphyry copper deposits. This is the most important type of copper deposit. North and South America contain large Porphyry copper deposits in its mountain regions.

Copper containing sedimentary rocks are another important type of copper deposit. These form one-fourth of the World’s copper resources. They are found in Central Africa and Zechstein Basin of Eastern Europe.

Copper deposits occurring individually contain millions of tonnes of copper. Open pit mining methods are used to commonly develop these deposits. Once the ore is discovered, mining operations last many years to extract the deposits in the area. Over the years, the mining regulations have been made stringent to minimize the impact of mining operations on the environment.

COPPER SUPPLY, DEMAND AND RECYCLING

The supply and consumption of copper have increased significantly in the past 30 years. These years have seen developing countries becoming a part of the global market, thereby increasing the demand for mineral commodities such as copper. Andean Region of South America has emerged as the leading producer of copper in the past 20 years. About 45 per cent of the World’s copper was produced in this region in year 2007.

The disruption of Copper supply is likely to have a severe impact on many industries such as construction and power transmission. However, the supply is expected to remain stable as the metal production is dispersed across the World and not limited to any particular region.

Of all metals, copper is of the widely recycled. It is estimated that around one-third of copper consumed is recycled. Copper and its alloys can be recycled safely for direct use or can be further processed to make refined copper. This does not affect any physical or chemical property of the metal and it remains as efficient as it is in the first use.

TYPES OF COPPER ALLOYS

Copper Alloys

Many copper alloys exist today having specialized utility. Copper when alloyed with zinc produces brass and when alloyed with tin produces bronze. It is also alloyed with nickel. An alloy of copper and nickel is call cupronickel. Depending upon the composition of these alloys, they have desired characteristics that are then used in specialized applications.

Copper is also an important constituent of carat gold and silver alloys. They are used to modify solidity, melting point and color of these metals.

The alloy of copper and nickel – cupronickel – is used in making coins by some countries. The 90 per cent copper and 10 per cent nickel alloy has great resistance to corrosion and hence are used in manufacturing of sea hulls and other equipments that are constantly exposed to the sea water.

Alloys of copper and aluminium also exist. Alloy consisting copper and about 7 per cent aluminium has a golden colour that is used in creating decorative pieces.

 Most of these alloys have exceptional resistance to corrosion and are very good conductors of heat and electricity. The high copper alloys are mostly used in advanced mechanical operations. Various grades of copper exist. They are classified on basis of the impurities they contain. Oxygen free copper is mostly utilized in application that requires ductile metal having good conductivity.

BRASS

­Brass is an alloy of copper and zinc. Alloys with 32 per cent to 39 per cent zinc are display very good hot working characteristics. However, cold workability of these alloys are only limited. The amount of zinc increases the strength and ductility of the metal at room temperature. Alloys that have more than 39 per cent of zinc content have higher strength and ductility than alloys that have lower content of the metal.  Depending upon the amount of zinc present in the alloy, the colour of brass ranges from red to a golden-yellow. Some common categorizations of brass depending upon the amount of zinc present in them are Commercial bronze, Red Brass, Jewellery Bronze, Cartridge Brass and Gilding Metal.

Brass is used in making jewellery, fire extinguishers, radiator cores, ammunition, lamp fixtures, gold plate bases and flexible hose. They are very easy to use for fabrication and have exceptional casting ability. They are also used in decorative hardware, low pressure valves, gears and bearings, architectural rims and plumbing fixtures. The alloy also has a very good corrosion resistance. Elements such as lead, phosphorous, manganese, chromium, beryllium and tellurium are also added to brass to further enhance its properties such as strength and durability. Most of these elements have negligible effect on its corrosion resistance properties.

TIN BRASS

Tin Brass are copper and zinc alloys. The zinc content in this alloy can range from 2 per cent to 40 per cent and tin content from 0.2 per cent to 3 per cent. This alloy is used to make electrical connectors, corrosion resistant mechanical products, springs, marine hardware, corrosion resistant screw machine parts, pump shafts and fasteners.

Tin Brass have a good cold workability and have great casting and fording ability. They are moderate in strength and corrosion resistance. However, it is a good conductor of heat and electricity. Brass is also modified by adding lead, tin and nickel for specialized use in marine applications. This alloy group is known by several names such as ounce metal, composition bronze and valve metal.

ALUMINIUM BRONZE

Aluminium bronze is an alloy of copper, zinc and aluminium. The alloy exhibits exceptional corrosion resistance characteristics, strength and resistance to wear and tear. They have good casting and forging ability. The corrosion characteristic of the alloy depends on the aluminium content.

Aluminium bronze containing 5 per cent to 12 per cent of aluminium have high corrosion resistance and high temperature oxidation. They are used in manufacturing hardware that comes in constant contact with seawater such as marine hardware and valve components, shafts and pumps for handling sea water, non-oxidising acids, sour mine water and industrial process fluids.

Aluminium bronze have exceptional quality to resist mechanical abrasions and chemical affects of sulphite solutions. Due to these characteristics, this alloy is used for blades and beater bars in wood pulp machines.

NICKEL SILVERS

Nickel Silvers are also known as Nickel Brasses. They contain copper, zinc and nickel. They are mostly used in making handling equipment for food and beverage products, electroplated tableware, musical instruments, optical and photographic equipment and decorative hardware.

These alloys do not contain silver. However, they get their name from its attractive silver lustre. It has moderate to high strength and have a good resistance to corrosion. C75200 and C77000 are the most common nickel silvers. They have good corrosion resistance in fresh as well as seawater. This is due to high nickel content in these alloys.

PHOSPOROUS BRONZE

Phosphorous Bronze are also known as tin bronze. They are alloys of copper, tin and phosphorous. They contain 0.5 per cent to 11 per cent tin and 0.01 to 0.35 per cent phosphorous. While tin helps in improving the strength and corrosion resistance of the metal, phosphorous improves the stiffness and the resistance to wear. These alloys have good resistance to seawater and most of the non-oxidizing acids with the exception of hydrochloric acid.

Phosphorous Bronze have high corrosion resistance, good soldering ability and formability, fatigue resistance, and exceptional spring qualities. Their prime utilization is in manufacturing of electrical products. Spring washers, bellows and diaphragms also use these alloys.

COPPER NICKEL ALLOYS

Copper nickel alloys have excellent resistance to corrosion. The common copper-nickel alloys are 70/30 and 90/10. These alloys are economical and are widely used in chemical industry. These alloys are superior to copper and its other alloys that resist corrosion and acid attacks. a defined composition of copper-nickel alloy is used in manufacturing of ship’s hull. This is to ensure that the hull does not corrode in seawater and reduction in adhesion to marine life

Human beings have been using lead for over 6000 years. It was one of the first metals known to man. Uses of lead has been documented in many ancient civilizations such as the Egyptians, Romans and Babylonians who used it for structural and ornamental purposes. Lead pipes built by the Romans are still in use in many places in the modern roman architecture.

Lead is soft and lustrous metal and is grey in colour. It has a low melting point and high density. Lead finds its uses in many industries. Building and infrastructure industry is one of the leading lead users. The metal is also used in manufacturing batteries, ammunition, weight, solders and pewter. Building construction, bullets, shots, lead acid batteries, radiation shields and fusible alloys are some of the most common applications of the metal.

Lead is in the carbon group with symbol Pb. The atomic number of the element is 82. It has the highest atomic number among the stable elements. It has four stable isotopes. Lead is a unique element, having 82 protons in the nuclear shell.

Lead is a heavy metal. When freshly cut, the metal has a bluish-white colour but it soon gets a dull grey colour due to tarnishing. It is a non-radioactive element. However, isotopes of lead are products of decay of naturally occurring radioactive elements.

Lead compounds are extensively used as colouring pigments in applications such as candles, ceramic glazes and projectiles. Lead is used as as inert anodic electrode in electro-winning applications. Introduction of lead in glass helps shield users from radiations in CRT and computer screens.

Lead is carcinogenic for humans and animals. If ingested it causes lead poisoning. Poisoning by lead affects organs such as heart, bones, kidneys, reproductive and nervous systems. Effects of lead poisoning include symptoms such as rise in blood pressure, kidney damage, brain damage, and decline in fertility.

Lead is one of the oldest known work hazard metal. There is no threshold established for lead exposure. Due to its colouring properties, lead compounds are used in paints. Exposure to lead containing paints are one of the major causes of lead poisoning. Most of the lead concentration found in environment are due to human activities such as use of lead in petrol.

Lead does not occur as a virgin metal in nature. It is most commonly found in combination with zinc, silver or copper ores. Most of the lead produced commercially is recovered along with these base metals.

Majority of lead ore found on earth’s crust is in form of galena (PbS). Other ores of lead include cerrussite and angelsite. Worldwide, Australia is the largest producer of lead account for about 19 per cent of total world lead production.

Salts of lead come out from exhaust of cars and contaminate soil and air. Rains carry these salts to waterbodies and lead to water pollution. The extent of lead pollution caused due to human activities is much more than that caused by the natural lead cycle. Concentrations of lead have been found high in food such as meats, sea food, vegetables and bottled water.

PROPERTIES OF LEAD

General properties

Symbol                                           Pb

Group, period, block                      14, 6 , p

Standard atomic weight                  207.2

Physical properties

Phase                                              solid

Density (near r.t.)                            11.34 g·cm−3

Liquid density at m.p.                     10.66 g·cm−3

Melting point                                   600 K, 327 °C, 621 °F

Boiling point                                    2022 K, 1749 °C, 3180 °F

Heat of fusion                                 4.77 kJ·mol−1

Heat of vaporization                       179.5 kJ·mol−1

Molar heat capacity                        26.65 J·mol−1·K−1

Vapor pressure

P (Pa)    1              10           100         1 k          10 k        100 k

at T (K)  978         1088         1229         1412         1660         2027

Characteristics

As a virgin metal, lead has a bluish-white tinge. The metal is very soft and without any support, it tends to sag and distort. Lead is one of the denser metals that occurs in nature. It has a bright lustre. However, once exposed to air it reacts rapidly with oxygen and forms oxides giving it a dull grey look. Lead it is highly ductile and malleable.

Due to formation of protective coating of oxides on lead, it is generally resistant to corrosion. Lead is very durable and stable in nature. It has a low melting point. It is resistant to most acids including chromic, sulphuric and phosphoric acids. However, lead it corrosive to alkalis and shows corrosion to hydrochloric, hydrofluoric, nitric and acetic acids.

Leas is a poor conductor of electricity compared to other metals. Lead has a high tendency to react with organic compounds. Lead metal burns with a bluish-white flame. It releases toxic fumes on burning.

High density of lead makes it very effective in shielding against x-ray and gamma radiations. Lead has low tensile and low creep strength. It is highly susceptible to creep. Low stresses causes lead to deform.

Alloys of Lead

Naturally, lead occurs in form of four isotopes – Lead -204, Lead-206, Lead-207 and Lead-208. Apart from stable isotopes, around 34 radio isotopes have also been synthesised in laboratory conditions. The most stable isotope of the metal is Lead-205, having half-life of over 10 to 7 years.

The Unified Numbering System (UNS) has defines the following grades of lead and lead-based alloys:

Pure leads L50000 - L50099

Lead - silver alloys L50100 - L50199

Lead - arsenic alloys L50300 - L50399

Lead - barium alloys L50500 - L50599

Lead - calcium alloys L50700 - L50899

Lead - cadmium alloys L50900 - L50999

Lead - copper alloys L51100 - L51199

Lead - indium alloys L51500 - L51599

Lead - lithium alloys L51700 - L51799

Lead - antimony alloys L52500 - L53799

Lead - tin alloys L54000 - L55099

Lead - strontium alloys L55200 - L55299

The most commonly used alloys of lead is Babbitt. Babbitt is a bearing metal and one of the several alloys used for a plain bearing or producing a bearing surface. The metal is named after Isaac Babbitt who invented it in 1839. The metal has got a characterized resistance to galling. It is soft and very easily damaged.

Lead is extensively alloyed with metals such as aluminium, zinc, copper and silver to produce different alloys of these metals.

Commercial grades of lead are commonly alloyed with elements such as antimony, tin, arsenic and calcium. Alloying of lead with small amount of antimony renders the metal hard and gives it greater strength. Lead antimony alloys range from 0.5 to 5 per cent typically.

Lead alloying with tin increases its strength and hardness and gives metal ability to wet and bond with metals such as steel and copper. Arsenic is used typically to harden the lead antimony alloys when needed.

Lead Ores and Occurence

Gallina is one of the most commonly occurring ores of lead. Lead occurs mostly in combination with copper, zinc and silver sulphadic ores. Most of the ores extracted do not contain more than 10 per cent of lead. Typically, not more than 3 per cent of it is economical to be extracted. Gallina, the most abundant ore containing lead, has 86.6 per cent lead by weight. Commercially extracted lead is obtained from sulphide ores which is smelted. Tupically, silver and gold are found along with lead ores and these are removed economically during processing of lead ores.

Very pure lead is obtained by electrolytic processing of smelting lead through betts process. This process produces lead bullion.

HISTORY OF LEAD

Lead was also extracted in Ancient Egypt for the first time. Its first use was seen in ancient Egptian civilizations where it was used to make sculptures and pottery. In 2000 B.C., lead was used in China to make coins. Lead has a high resistance to corrosion. This was discovered by the Greeks, who used the metal to apply over ship hulls as a protective layer.

By 100 A.D., Romans were producing about 80,000 tonnes of lead every year. The metal was being used in their plumbing till 20^th century. However, lead poisoning was one of the main reasons why the use of lead was curtailed. In Middle Ages, some European regions used lead for their roofing as it has a very good resistance against fire. Later, lead was increasingly used in forging cutlery and pewter. With invention of firearms, lead was used in manufacturing bullets.

PRODUCTION

Lead has very high recyclability. Recycled lead makes for about half of the lead that is produced every year. In 2012, worldwide production of lead exceeded 10 million tonnes. Australia, China and USA are the largest lead producing countries.

Galena is the most economically important lead ore. This ore contains lead sulphide along with zinc and silver. The ore can be used to procure all these metals. Anglesite and Cerrusite are other ores that are mined to extract lead.

Most of the lead produced is utilized in manufacturing lead acid batteries, sheets and other application that supports recyclability.

USES OF LEAD

Manufacturing of lead acid batteries accounts for 80 per cent to 90 per cent of lead usage. These batteries have a large power to weight ratio which makes it ideal for all types of vehicles. These batteries are also used for power storage at hospitals and other places that requires emergency power storage. Wind energy and solar energy projects also use these batteries as storage cells.

Lead is used as a type metal in printing industry. Lead sheathing is normally extruded around electrical and communication cables to give them protection against moisture and corrosion damages. Lead sheets are used typically in providing protection for rooms where x-rays, gamma rays, high vibrations and high-pitch sounds are present.

Lead-tin systems are the most common alloying materials used for joining other metals.

Lead is a very reactive metal. To make it more stable, lead compounds are used. Lead oxide is one such compound. The metal and its compounds have high resistance to corrosion and hence is one of the material of choice for iron and steel coating. These coatings are used over ship hulls. Underwater communication and power cables are also protected using the metal coatings.

Lead is also used in making ammunition such as bullets. The metal is also used as a solder since it has a low melting point. Some other uses of lead include manufacturing of camera lenses and optical instruments. Lead glass is one of the important components of these equipments. Further, lead crystal is used for making decorative items. Lead is also used in making fireworks, paints and matchsticks. 

Anodes made of lead alloys are used in electro plating of metals such as manganese, copper, nickel and zinc. These anodes are made of lead alloyed with calcium and tin. Previosuly lead alloyed with silver was used as anodes. However, lead-calcium-tin alloyed anodes show higher resistance to corrosion to environments containing higher concentrations of sulphuric acids.

WHY LEAD?

Lead is one of the preferred metals to work with. It is a highly durable metal that lasts longer than most of the man-made products. It has a high recyclability and has one of the lowest carbon footprint among all the hard metals available. It is one of the most sustainable building materials. Not only it is environment friendly but also economical.

Background

Nickel is silvery-white with slight golden tint, lustrous, hard, malleable, and ductile metal. It is one of the transition metals. Nickel is a fairly good conductor of electricity and heat. Pure nickel has a significantly high chemical reactivity. However, this is apparent when the metal is powdered to expose maximum surface aea for chemical reactions to occur. Finely powdered nickel can adsorb hydrogen. Rection with nitric acid renders the metal passive.

Nickel is the only element named after the devil. The name comes from the German word Kupfernickel, meaning "Old Nick's copper," a term used by German miners. Early copper miners were confused about ores of nickel and copper as they had a green tint. But copper ores reacted differently to heat than did nickel ores. This confusion led to the choice for nickel's name. Nickel ores are also similar to cobalt ores. But they also do not react chemically in similar way. In the modern world, the metal was isolated in 1751 by Axel Fredrik Cronstedt, who initially mistook its ore for a copper mineral. He was able to isolate the metal and conclude that it was an entirely new metal.

Nickel has a tendancy to combnine with oxygen in the atmosphere and generally, native Nicjkel metal it not found in earth’s crust. Native Nickel is generally found in combination with Iron. Most of the Nickel is locked away deep in the earth’s molten crust along with iron. This constitutes around 10 per cent. Nickel in the earths surface occurs with sulphur in millerite. With arsenic it is combined in the mineral niccolite. Nickel Glance is another important mineral where it is combined with arsenic and sulphur. Russia, Australia, New Caledonia, Cuba, Canada and South Africa are major regions where the mining of this metal is done.

Nickel is one of four elements that are ferromagnetic around room temperature. This makes it an metal suitable for production of AlNiCo magnets. About 60 per cent of the nickel production is used for alloying of steels. Nickel compounds are widely used as catalys in hydrogenation reactions. Nickel also occurs in enzymes of many microorganism and plants.

Nickel is anticipated to be a carcinogenic. An uptake of too large quantities of nickel has the following consequences:

- Higher chances of development of lung cancer, nose cancer, larynx cancer and prostate cancer

- Sickness and dizziness after exposure to nickel gas

- Lung embolism

- Respiratory failure

- Birth defects

- Allergic reactions such as skin rashes, mainly from jewelry

General properties

Symbol                                   Ni

Atomic Number                       28

Element category                    transition metal

Group, period, block                10, 4, d

Standard atomic weight            58.69

Physical properties

Phase                          Solid

Density                        8.908 g·cm−3

Liquid density at m.p.  7.81 g·cm−3

Melting point                1728 K, 1455 °C, 2651 °F

Boiling point                 3003 K, 2730 °C, 4946 °F

Heat of fusion              17.48 kJ·mol−1

Heat of vaporization     379 kJ·mol−1

Molar heat capacity      26.07 J·mol−1·K−1

Vapor pressure

P (Pa)   1          10        100      1 k       10 k     100 k

at T (K) 1783    1950    2154    2410    2741    3184

Characteristics

Nickel is a silvery-white metal with a slight golden tinge. Nickel can be finely polished. Nickel is hard and ductile. Apart from iron, cobalt and gadolinium, nickel is the only metal that is ferro magnetic at room temperature. Its Curie temperature is 355 °C. The unit cell of nickel is a face centered cube with the lattice parameter of 0.352 nm, giving an atomic radius of 0.124 nm. Nickel belongs to the transition metals.

Naturally occurring nickel is composed of five stable isotopes; 58Ni, 60Ni, 61Ni, 62Ni and 64Ni with 58Ni being the most abundant. Seven radioactive isotopes of nickel are also known.

Occurrence

Nickel makes up about 0.01 to 0.02 percent of the Earth's crust. It is the 22nd most abundant metals in Earth.

Most of the nickel occurs combined with sulfur and iron in pentlandite ore, with sulfur in millerite ore, with arsenic in the nickeline ore, and with arsenic and sulfur in nickel galena. Nickel is commonly found in iron meteorites as the alloys kamacite and taenite.

The bulk of the nickel mined comes from two types of ore deposits. The first are laterites, where the principal ore minerals are nickeliferous limonite and garnierite. The second are magmatic sulfide deposits, where the principal ore mineral is pentlandite.

Australia and New Caledonia have the biggest estimated nickel reserves.

Meteorites often contain a high percentage of nickel.

World Production

Philippines, Indonesia, Russia, Canada and Australia are the largest producers of nickel in the world. At least 130 million tons of Nickel is readily available in deposits containing at least 1 per cent nickel. About 60% is in laterites and 40% is in sulfide deposits. In addition, extensive deep-sea resources of nickel are in manganese crusts and nodules covering large areas of the ocean floor, particularly in the Pacific Ocean.

ALLOYS OF NICKEL

Alloys of Nickel have high corrosion resistance, high temperature strength and their special magnetic and thermal expansion properties. This makes it very useful in many applications. The major alloys of nickel include:

-          Iron-Nickel-Chromium alloys

-          Stainless Steels

-          Copper-Nickel alloys and Nickel-Copper alloys

-          Nickel-Chromium and Nickel-Chromium-Iron alloys

-          Low Expansion Alloys

-          Magnetic Alloys

Stainless Steels

Stainless steel is resistant to corrosion, rusting and staining as compated to normal steels. These properties are provided to Stainless Steel by allouing it with chromium and nickel. Stainless steels contain typically 8 – 10 % nickel. The most widely used grade of Stainless Steel is SS304. This is a combination of 18 per cent Chromium and 8 per cent Nickel. This has good corrosion resistance and is used for the items such as plates, spoons, forks, sinks etc. The other widely used grade is SS316. This grade has much superior corrosion resistance and is used for the construction of equipment where corrosion is a challenge.

Nickel Copper Alloys

Nickel copper alloys are commonly called as Monel or Nicorres. These are primarily made of Nickel alloyed with copper along with small quantities of iron and manganese. The alloy work hardens quickly and hence is difficult to machine. It is used in highly corrosive environments. Nickel copper alloys contains 63% nickel minimum, 28-34% copper, and a maximum of 2% manganese and 2.5% iron. Nickel copper alloys are widely used in oil refining and marine applications where long corrosion-free life is required. They exhibit good thermal conductivity and are used for heat exchangers where sea water is one of the fluids concerned.

Nickel Chromium Base Alloys

Nickel chromium base alloys typically find applications heat resistance and/or corrosion resistance is required. In less demanding conditions, nickel is replaced by iron to decrease the overall cost. Where corrosion resistance is significant, molybdenum is used as an alloying addition in nickel chromium based alloys. These alloys are listed in the Unified Numbering System. Common trade names are HASTELLOY, INCOLOY, INCONEL, NICROFER, NICROM and NIMONIC.

Low Expansion Alloys

These alloys exhibit low expansion co-efficiency over a wide range of temperatures. Typical applications include precision springs and acting as a glass metal seal.

Magnetic Alloys

Nickel magnetic alloys have a high magnetic permeability which allows these alloys to have significantly lower power consumption per unit of magnetic field produced. There is a wide range of combinations possible and the alloying is done based on the requirements. Applications are found in wide areas such as the head of a tape recorder, shielding in cathode ray display devices, telephones etc.

Overview

After iron, copper and aluminium, zinc is the most commonly used metal. It is a lustrous metal that is bluish-white in colour. On exposure to air, it gets a silver-white coating. Zinc has a high recyclability. It can be recycled indefinite times without losing any of its physical or chemical properties.

Zinc is found abundantly in the crust of the earth. The metal has many industrial as well as biological uses. It is an important part of our diet.

Zinc is not a very strong metal and is brittle. It is not used for any application that requires load bearing. However, zinc alloys have higher strength than other alloys used for diecasting. Zinc is a fair conductor of heat and electricity. However, it has very strong electrochemical properties. This makes it an important material in alkaline batteries and galvanising process.  

Zinc occurs naturally in the environment and is a part of the earth’s crust. Zinc is present integrally in the soil, rocks, air, water and is also one of the essential minerals required for cellular growth in all organisms. Zinc metal is commercially referred to also as Spelter. Spelter can refer to the copper-zinc alloys that are produced or to the smelted zinc ingots.

Zinc has atomic number 30 and the symbol for the metal is Zn. Zinc is found in the earth’s crust as ore and is 24th most abundant element in the earth. Before zinc was discovered in its nascent metallic form, the ores of zinc found applications in the making of brass. Zinc compounds also have healing and medicinal properties and were used for the treatment of wounds and other ailments. Brass is believed to have been made in the year 20 BC -14 AD in Rome.

In the year 1374, in India, Zinc metal and zinc oxide were produced at Zawar. Andreas Sigismund Marggraf, a German chemist is credited for the discovery of Zinc in the Western world. Major applications of Zinc include Corrosion-resistant zinc plating of iron batteries, small non-structural castings, and alloys such as brass. Compounds of zinc find application in products such as dietary supplements, deodorants, anti-dandruff shampoos, and luminescent paints and in organic matter synthesis.

Zinc is an essential nutrient that is required for the healthy development of humans.  Deficiency of Zinc affects close to one third of world’s population and is associated with a number of diseases.

Geographical locations with the largest deposits of Zinc include Australia, Asia, and the United States. Commercial production of Zinc includes various technologies such as froth flotation of the ore, roasting, and final extraction by electro winning.

General properties

Symbol                                           Zn

Group, period, block                      12, 4, d

Standard atomic weight                  65.38

Physical properties

Phase                                              solid

Density (near r.t.)                            7.14 g·cm−3

Liquid density at m.p.                     6.57 g·cm−3

Melting point                                   692.68 K, 419.53 °C, 787.15 °F

Boiling point                                    1180 K, 907 °C, 1665 °F

Heat of fusion                                 7.32 kJ·mol−1

Heat of vaporization                       115 kJ·mol−1

Molar heat capacity                        25.470 J·mol−1·K−1

Vapor pressure

P (Pa)    1              10           100         1 k          10 k        100 k

at T (K)  610         670         750         852         990         1179

Characteristics

Zinc is a bluish white, lustrous and a diamagnetic material. However the metal, reacts rapidly with carbon – dioxide in the air and forms a protective layer. This leads to the metal normally having a dull metallic finish.

Zinc is hard and brittle. It attains malleability at temperatures between 100 to 150 degrees, but the metal becomes brittle at 210 degrees. Zinc is a fairly good conductor of electricity. It has a low melting point of 420 degree C with a boiling point of 907 degree C. Zinc is mildly reflective metal with as reflectivity of 80%. It is a moderately reactive metal and a strong reducing agent.

The metal burns in air with a bluish-green flame and forms zinc oxide. It is reactive with both acids and alkalis. Zinc is widely used for alloying with various metals such as Aluminum, Copper, Antimony, Bismuth, Gold, Lead, Mercury, etc.

Alloys of Zinc

Zinc has two main alloys

1. Brass
2. ZAMAK (Aluminium, magnesium, copper)

Brass

Brass is an alloy of zinc along with copper. The prpoprtions in which the alooying of these two metals is done, ontrols the properties of the product. Brass is malleable and has got acoustic properties. This makes it idle for the production of musical instruments. Due to its lower melting poijnt, it is widely used for castings. The copper in brass provides it with germicidical properties. Addiiton of upto 2 percent lead in brass enhances its machiniablility. Brass is recyclable and around 90 percent of it is recycled.

Zamak

Zamac is a family of zinc alloys with varying proportions of Aluminium, magnesium and copper.These alloys were developed in 1929 by the New Jersey Zinc Company. Countries have adopeted various standards for the naming and defining the chemical compositions of the Zamac alloys. Zamac 2,3,4,5,7 are the most common Zamac alloys.

Zamac 2 and 3 have the same chemical compostion with exception of copper, which is increased by 3 per cent. This increases the mechanical strength of the allo. Zamak 2  has the maximum strength of all the Zamak alloys. It is widely used for the manufacture of short run injection moulding dies. Zamak 3 is widely used for the making of die castings. It has excellent dimensional stabilities and castibilities.

Zamak 4 was developed for the Asian markets

Zamak 5 is widely used in the European market

Zamak 7 has lower magnesium compared to Zamak 3 which increases it fluidity and ductility. It is use for the casting of thin wall components.

Zamak alloys are wisely used of the production of goods sch as plumbing fitings, bathroom fixtures, staplers, handles, locks, toys, fans, golf clubs etc.

ZINC ORES AND OCCURRENCE

Around 95 per cent of the zinc produced, is made from sulfide ores. The main ore of Zinc is  sphalerite (ZnS). This is typically found mixed with sulfides of copper, lead and iron. The world’s largest zinc mine is the Rampura Agucha Mines in Rajasthan India. Many countries in the world have got deposits of Zinc. The major miners and producers of Zinc are Australia, Canada, Chile, Peru, and USA. Underground mining of zinc ore is done in most of the places.

HISTORY OF ZINC

Use of zinc has been traced to 500 B.C. Products made with zinc alloys have been found in the archaeological findings of this era. Zinc was alloyed with copper to make brass around 200 B.C. Initially, the brass was used as a replacement to bronze. It was used to forge coins, weapons and for decorative items. In 1746, Andreas Sigismund Marggraf isolated zinc, describing its process and establishing the basic theory.

The first battery using zinc and copper plates was created by Allesandro Volta in 1800. This brought in a new phase of electrical engineering. In 1837, Stanislad Sorel invented the process of galvanisation. Galvanisation is a process of zinc plating on variety of metals to provide a cathodic protection. It is now the most important application of pure zinc in industries.

PRODUCTION

In 2011, worldwide Zinc production exceeded 13 million tonnes. Sphalerite, a zinc sulphide mineral, is the most economically important zinc ore. About 70 per cent of the World Zinc comes from mining. The remaining 30 per cent comes from recycling. 95 per cent of zinc produced in the World is mined from these ores. China, Peru, United States, Australia and Canada are the largest producers of zinc in the world.

Production process of zinc involves froth floatation of the ore, followed by roasting and finally extraction using electrical processes. After the zinc ore is grinded, mineral is separated from gangue with the process of froth floatation. This process helps in reaching a concentration that includes about 50 per cent zinc. The remaining component is sulphur and iron. After this, roasting helps in converting the concentrate into zinc oxide. Pyrometallurgy or electrowinning pyrometallurgy processes are used for further processing of zinc oxide.

Other mineral ores that are used to extract zinc are smithsonite, hemimorphite, wurtzite and hydrozincite. Total zinc resources in the World have been estimated to 1.9 billion tonnes. Around 70 per cent of the metal comes from mining. The remaining comes from recycling. Pure Zinc is called Special High Grade (SHG) and is 99.995 per cent pure.

USES OF ZINC

Zinc, with its alloys, has been in use since thousands of years. It is the 24^th most abundant metal of earth. The earliest use of zinc was in brass which is an alloy of copper and zinc. This alloy was used to make ornaments, weapons, coins, mirrors and decorative pieces.

Today, more than half of the zinc produced is used in Galvanizing. With Galvanization, ferrous and non-ferrous metals are coated with a layer of pure zinc by electroplating or dipping it into molten zinc. This protects the metals from corrosion and other elements.

Zinc is light in weight and highly corrosion resistant. This makes it an ideal material for using in die casting alloys. Around 14 per cent of zinc produced worldwide is used to produce die casting alloys. Approximately, 10 per cent of the production is used to make brass and bronze.

Rolled zinc applications, which includes down pipes, gutters and roofing, also utilizes significant share of the worldwide production of Zinc. The remaining share is consumed in making zinc compounds such as zinc oxide and zinc sulphate. Zinc is then converted in a wide range of products for application in various areas such as transport, consumer goods, electrical appliances, construction and engineering.

Corrosion resistance coatings on Steel

Zinc metal provides an excellent corrosion resistant coatings for steel. This protection is provided primarily due to the anodic dissolution of zinc compared to iron. Zinc acts as a sacrificial anodes and gets corroded. Typically, for corrosion resistance, Zn/Co and Zn/Ni deposits are used for providing the coatings.

Galvanizing is used to protect water immersed structures such as ships’ hulls, drilling rigs and pipelines. Also, as the zinc layer acts as sacrificial anode, it provides protection to the bare areas in a zinc coating on steel, caused by damage or operations such as cutting or drilling. Alkaline Zn/Ni coatings are used to coat the car bodies.

Zinc coatings were applied by galvanization, where the parts to be protected were dipped in molten zinc. This process was not capable of getting good finishes. Several refinements have happened in this galvanization process over the years. Other process for the coating of zinc include electro deposition, flame sprayed coatings, mechanical plating and application of zinc rich paints.

Developments in Galvanization

With the advancement of technology, several improvements have been made in the galvanization process, whereby it has become possible to control the thickness and the surface finish of the zinc coatings. A series of alloys have also been developed for the application. Several alloys such as Galvalume which consists of about 55% aluminum and 45% zinc with a small amount of silicon. These alloys provide better corrosion resistance than the native zinc metal.

Automotive sector

Improvements in the zinc application technologies have stimulated the development of new applications. Galvanized steel with controlled surface finish is used to produce parts of car bodies that are vulnerable to corrosion. The surface finish of the coated steel is maintained such that there is no visible difference in appearance after painting between panels with and without the zinc protection. Applications in the automotive industry, for the protection of body panels, are a major market for zinc.

Building and Construction Industries

Building and construction industries worldwide, use at around two thirds of all the coated steel strip produced. These find application in the making of roofing and claddings of buildings. The zinc coating can be given a colour. The life of this color coated steel is very long.

IN the European and American continents, the galvanized steel is quickly replacing the traditional timber frames of the buildings. These provide better strength and do no warp with time as compared to timbre.

Overview

After Silicon, Aluminium is the second most abundant metal element in the Earth’s crust. However Aluminium is never found as a free metal in nature. It exists as compounds combined with the other elements in nature.  Aluminium was first produced by Christian Oersted in 1825 in tiny quantities. Wohler, a German scientist, fused anhydrous aluminium chloride with potassium to set free aluminium. Wholer’s methods were improved by Ste Claire Deville who in 1854 put together a production process for the commercial production of Aluminium.

In the 1880’s, there were two breakthroughs that greatly increased the availability of aluminium. The first of these was a new process for obtaining aluminium from aluminium oxide by Charles Martin Halland Paul L. T. Héroult who each invented this process independently in 1886. The second was a new process that could cheaply obtain aluminium oxide from bauxite. Bauxite is an ore of aluminium, largely found in the earth’s crust,  containing a large amount of aluminium hydroxide (Al2O3·3H2O). Karl Joseph Bayer developed this process in 1888. The Hall-Héroult and Bayer processes are still used today to produce nearly all of the world's aluminium.

Aluminium is being produced in large quantities for commercial consumption since 1886. In past century, the aluminium consumption and supply has increased dramatically. In the year 1900, the total annual aluminium production was 1000 tonnes. This figure reached 31 million tonnes by the end of 2005, making aluminium the second most consumed metal in the World.

Aluminium has several properties that make it an excellent metal for domestic, commercial and industrial use. They are lightweight, corrosion resistant, ductile, impermeable, recyclable and good conductors of heat and electricity. These properties are further enhanced with making alloys of aluminium with other metals. Recycling is one of the best properties of this metal. It can be recycled infinitely, without modification in any of its properties. Today, aluminium is used in a wide range of applications. The usability of the metal continues to further grow as new industrial innovations continue to experiment with the metal to improve efficiency and durability of their products.

Some of the common applications of aluminium can be seen in the building industry and household product manufacturing. In household products, aluminium is used in manufacturing utensils such as kettles, lamps, lemon squeezers etc. Aeronautic industry also uses aluminium in form of its alloys for several applications. Aluminium is also increasingly being used in making jewellery, furniture and accessories. The metal is also used in making fireman suits, aeronautical suits and protective wears for professionals such as scientists and laboratory technicians.

Physical and other properties of Aluminium

Physical properties

Phase                                     Solid

Density (near r.t.)                 2.70 g·cm−3

Liquid density at m.p.         2.375 g·cm−3

Melting point                        933.47 K, 660.32 °C, 1220.58 °F

Boiling point                         2743 K, 2470 °C, 4478 °F

Heat of fusion                      10.71 kJ·mol−1

Heat of vaporization          284 kJ·mol−1

Molar heat capacity           24.20 J·mol−1·K−1

Atomic properties

Oxidation states                   3, 2[1], 1[2](amphoteric oxide)

Electronegativity                 1.61 (Pauling scale)

Ionization energies

1st:                                         577.5 kJ·mol−1

2nd:                                        1816.7 kJ·mol−1

3rd:                                         2744.8 kJ·mol−1

Atomic radius                       143 pm

Covalent radius                   121±4 pm

Van der Waals radius         184 pm

Vapour pressure:

Characteristics

Aluminium is a soft, ductile, malleable and light weight metal. Freshly produced aluminium is slivery in colour. However it oxidises and becomes dull grey once it is exposed to air. Aluminium is a good reflector of visible light and an excellent reflector of medium and far infra-red radiations. The metal is easily casted, drawn extruded and machined. Because of these properties, Aluminium finds a lot of industrial uses. Aluminium alloys have far superior strengths and properties than the metal itself.

Pure aluminum metal is low in strength and is soft. Alloying of aluminum with other metals helps it in improving certain physical and chemical properties. Aluminum alloys are typically of lower weight that than comparable other metals having similar properties. Typical alloying metals with aluminum include copper, magnesium, silicon and zinc. Aluminum alloys find special applications in aerospace industry due to their high strength to weight ratios.

There are two main types of aluminum alloys – wrought aluminum alloys and cast aluminum alloys. Around 85% of the aluminum is used for the production of wrought aluminum products. Cast aluminum alloys are cheaper and more cost-effective and are used where lower tensile strengths can be tolerated.

ALUMINIUM ALLOYS

Wrought Alloys

These are named according to the International Alloy Designation System. Each alloy is given a four digit number with the first digit representing the major alloying element

• 1000 series is pure aluminumwith a minimum 99% aluminum
• 2000 series is alloyed with copper.
• 3000 series is alloyed with manganese.
• 4000 series is alloyed with silicon.
• 5000 series is alloyed with magnesium.
• 6000 series is alloyed with magnesiumand silicon.
• 7000 series is alloyed with zinc.
• 8000 series is alloyed with other elements which are not covered by other series.

Cast Alloys

The Aluminum Association, a non-profit organization based in Arlington, Virginia, United States, is a trademark association for aluminum production, fabrication and recycling industries. The nomenclature adopted for Cast alloys is comparable to that adopted for the naming of wrought alloys. The first digit represents the metal being alloyed.

• 1xx.x series are minimum 99% aluminum
• 2xx.x series is alloyed with  copper
• 3xx.x series is alloyed with  silicon, copper and/or magnesium
• 4xx.x series is alloyed with  silicon
• 5xx.x series is alloyed with  magnesium
• 7xx.x series is alloyed with  zinc
• 8xx.x series is alloyed with  tin
• 9xx.x other is alloyed with  other elements

IMPORTANT ALLOYS OF ALUMINUM

Aluminum – Copper alloys

Series 2XXX. These alloys have typically higher Copper content along with Silicon, Manganese and Magnesium. These alloys due to their lower resistance to sol working and lower corrosion resistance, needs to be anodized. They find application in aircraft and military uses.

Aluminum - Manganese Alloys

Series 3XXX. These alloys are produced by mixing aluminum with approximately 1% manganese. Addition of manganese greatly increase the strength of the metal by 10-15%. Major use of these alloys is in roof sheeting and vehicle paneling.

Aluminum-Silicon Alloys

Series 4XXX. Sufficient addition of silicon to aluminum substantially lowers the melting point of the metal. This alloy finds uses in soldering, filler alloys etc. during metal working.

Aluminum Magnesium alloys

Series 5XXX. These alloys exhibit high strength with increased resistance to corrosion especially in marine/sea water conditions.  Products made from this alloy find use in pressure vessels, chemical plants, bulk rail and road vehicles and ships.

Aluminum - Magnesium - Silicon Alloys

Series 6XXX. Addition of Magnesium and Silicon to Aluminum renders it heat treatable. They have good mechanical strength along with increase corrosion resistance and ability for easily forming shapes. The alloy is used for making building structures, road vehicles and ships.

Aluminum-Zinc-Magnesium and Aluminum-Zinc-Magnesium-Copper Alloys

Series 7XXX. This group alloys exhibit the highest tensile strengths of all the alloys of Aluminum. Addition of zinc and magnesium makes the alloys heat treatable and gives them their very high strengths. However, these alloys are difficult to manufacture. They find use in military applications primarily.

OCCURRENCE

Aluminium is one of the most abundant elements of the earth crust. Approximately, it makes up 8.1% by weight of the earth’s crust. Aluminium is highly reactive in nature. IT tends to react rapidly with chemicals and form compounds. Hence as a metal it does not occur in free state in the earth crust. But the element is the third most abundant element on earth after Oxygen and Silicon. Aluminum is concentrated in the outer 10 miles (16 km) of Earth’s crust. The name aluminum is derived from the Latin word alumen, used to describe potash alum, or aluminum potassium sulfate, KAl(SO4)2·12H2O

Aluminium exists primarily as Alumino-Silicates (i.e. as Felspar, NaAlSi3O8, or KAlSi3O8, or CaAl2Si2O8), in igneous rocks and as Clays, H4Al2Si2O9, in sedimentary rocks. Aluminium has three principal ores:

-          Gibbsite or Hydrargillite, Al2O3.3H2O,

-          Bauxite, Al2O3.2H2O, Diaspore, Al2O3.H2O, and

-          Cryolite, AlF3.3HF

Most of the aluminium produced today is made from Bauxite. Bauxite derives its name from the village of Les Bauxs in Southern France where it was discovered in 1821. The name Bauxite refers to an ore or to a mixture of minerals rich in hydrated oxides, formed of aluminous rocks such as nepheline, feldspars, serpentine, clays, etc. During weathering the silicates are decomposed and the decomposition products are leached out, leaving behind a residue enriched in alumina, iron oxide, and titanium oxide but still containing some silica.

Most bauxite ore contains 40-60% alumina, either as the trihydrate gibbsite or as the monohydrates boehmite and diaspore.

USEFUL PROPERTIES OF ALUMINIUM

Weight: Aluminium is one of the lighter metals with a density one-third that of steel. It has a higher weight to strength ratio.

Strength: Aluminium in pure form is a soft metal. However, its alloys have high tensile strength. IT also does not become brittle at lower temperatures.

Machining: Aluminium is easy to work with. It is relatively soft and easily can be milled, drilled, punched, bent etc.

Conductivity: Aluminium is an excellent conductor of electricity and heat. It finds application in conductors for this very reason as Aluminium conductors weigh only half as that of copper conductors and are cheaper.

Reflectivity: Aluminium sheets are a good reflector of visible light and near infrared radiations.

Corrosion Resistance: Aluminium metals reacts with oxygen in air to form a layer of oxide. This oxide layer serves to act as a protective layer for the metal and saves it from further corrosion. However in highly acidic environments, the corrosion of aluminium is rapid.

USES OF ALUMINIUM

Aluminium is an economical and versatile metal. It find uses in a wide variety of industries and owing to the cost-effectiveness of the metal, it continues to attract innovators to explore further use of this metal. The automotive, infrastructure, cookware and electrical industries see a wide application of the metal and its alloys.

Aluminium in Automotive industry

Automotive industry is one of the leading consumers of aluminium today. To make the cars lighter, faster, with increased fuel efficiency, designers are increasingly employing this metal in their innovations. Its corrosion resistant and non-sparking characteristics also lead to its increased used in the sector. Aluminium helps in making the vehicles fuel efficient and lesser emissions. It is estimated that replacing heavier materials in car manufacturing with aluminium will contribute substantially towards fuel efficiency. By replacing one kilogram of heavy material such as steel or iron with aluminium in a vehicle can save 20 kilogram of carbon dioxide emission over the life period of the vehicle. It can be higher for certain other transport systems such as trains. In trains every kilogram of heavy material when replaced with aluminium can save up to 80 kilogram of carbon dioxide over the operating life of the train.

Increase in aluminium usage in car manufacturing is increasing every year as car manufacturers strive to improve the fuel efficiency of their cars. About 20 years ago, aluminium accounted for about 40 kg to 80 kg in an average car. In 2009, this figure rose to about 120 kg. Today, aluminium makes for 50 per cent of the total scrap value in a car.

RECYCLING OF ALUMINIUM

Aluminium metal is theoretically 100% recyclable. The recycling of the metal is done by melting the metal scrap in the first stage. A significant amount of Aluminium is lost in the form of dross in during this process. The dross can be further processed to recover more Aluminium. The melted metal I cast in the form of billets which are used as feed for various processes.

Recycled Aluminium, commonly known as secondary Aluminium, has the same physical properties and characteristics as virgin Aluminium.

Recycling of Aluminium consumes roughly 5% of the energy that is required to produce virgin metal. This drastic reduction of energy makes the metal cost effective and also reduces the impact on the environment.

Tin is a silver-white metal that has resistance to corrosion from water. However, it does not have any resistance to attack from acid salts and alkalis. Oxygen in solution accelerates the attack to the metal.The sound heard when it is beaten is called TINCRY.Tin is malleable, ductile and highly crystalline. A tin cry is heard when we bend this metal. This sound is made by the breaking crystals of the metal. Bronze was the first alloy of tin used in large it. Bronze is an alloy of tin and copper and its use has been traced back to 3000 B C. Pure metal tin was produced after 600 B.C.

Pewter is an important alloy of Tin. It uses around 85 per cent to 90 per cent tin. The other components of pewter may include copper, lead and antimony. Pewter has been used for making cutlery till 20^th century. Today, tin is used in many important alloys. Tin solders containing 60 per cent or more tin are widely used. Besides, tin is used for corrosion resistant plating of metals such as steel. It is also used for plating metals that are used in food packaging. This is because of its lo toxicity.As tin is highly crystalline, it is also one of the component in bell metals.

Tin is mainly obtained from Cassiterite mineral ore. It occurs as a tin dioxide in this ore.

PROPERTIES OF TIN

Atomic Symbol: Sn

Atomic Number: 50

Atomic Mass: 118.71 amu

Melting Point: 231.9°C

Boiling Point: 2,603°C°C

Density: 7.31g/cm³

HISTORY OF TIN

The earliest known use of tin was in the form of its alloy Bronze which dates to about 3000 B.C. However, this alloying is expected to be unintentional as Bronze in the early times has very little tin or arsenic of about 2 per cent. It is believed that this content was present in bronze due to traces of nickel content in copper ores. Bronze with arsenic was seen to be used in Near East region. The main reason is the presence of arsenic in copper ore in this region. However, health risks of arsenic were soon recognized and demand for tin bronze increased.

Adding a metal to copper helps in increasing it hardness and lower its melting point. Further, it also improves the casting ability of the metal. Discovery of this helped man to use bronze to cast equipments of complex shapes.

Cassiterite is a tin oxide mineral that is assessed to be the original source of tin. Sulphide ores such as stannite are other important forms of tin ores.

PRODUCTION

Tin is one of the first metals that was mined by man. Its shiny finishing along with strength, made it a popular metal that was used in many applications since the earliest times. Today, tin is majorly used for producing solder and in iron and steel plating. Production of bronze and pewter are still one of the major uses of the metal. Further, tin is used in modern engineering and in making diecasting alloys.

In 2011, tin production of the World was reported at 383,500 tonnes. Asia was the largest contributor with 83 per cent of the production coming from Asian countries.

Tin is 49^th most abundant element in the Earth’s crust. Cassiterite is the economically most important tin ore in which the metal occurs as a tin dioxide. Sulphides such as Stannites, Franckeite, Canfieldite, Cylindrite and Tealite are other ores that can produce small amount of tin.

Cassiterite is generally found in placer deposits. Since tin oxide is heavier, weathering of mineral rick results in concentration of tin elements in alluvial deposits such as valleys, stream beds etc. Dredging, open cast mining and hydraulic methods are cost-effective mining methods for tin. Recycling of the metal is also an important source of the metal.

USES OF TIN

Tin is in use from the very early ages. Its first usage was in form of Bronze in about 3000 B.C. Discovery of alloying tin with copper to make bronze marks one of the most important discoveries of the ages. In the early years, this alloy was used to make weapons, utensils, ornaments and decorative items. Much later, during the period of ancient Rome, tin was used as Bronzes and also for tinning copper vessels.

Today, majority of the tin produced in used in production of solders. Tin plating of iron and steel are also one of the main consumers of the metal. Further, tin continues to be used in bronze production, specialized alloys and diecasting alloys.

In 2011, 52 per cent of the World Tin production was used in making solders. Tin plating consumed 17 per cent of the metal worldwide production. 15 per cent of the total production was used in chemicals industry. About 10 per cent was used to make brass and bronze products and about 2 per cent for making glass. The remaining 10 per cent was used in other applications.