See also: Graphene

Graphite
massive graphite silver specimen
General
Category	Native mineral
Chemical formula	Carbon, C
Identification
Color	Steel black, to gray
Crystal habit	Tabular, six-sided foliated masses, granular to compacted masses
Crystal system	Hexagonal (6/m 2/m 2/m)
Cleavage	Perfect in one direction
Fracture	Flaky, otherwise rough when not on cleavage
Mohs Scale hardness	1 - 2
Luster	metallic, earthy
Refractive index	Opaque
Pleochroism	None
Streak	Black
Density	2. Graphene is a one-atom-thick planar sheet of sp2-bonded Carbon atoms that are densely packed in a honeycomb crystal lattice A mineral is a naturally occurring substance formed through geological processes that has a characteristic chemical composition a highly ordered atomic structure and specific A chemical formula is a way of expressing information about the Atoms that constitute a particular Chemical compound, and how the relationship between those atoms changes Carbon (kɑɹbən is a Chemical element with the symbol C and its Atomic number is 6 In Mineralogy, shape and size give rise to descriptive terms applied to the typical appearance or habit of Crystals The many terms used by mineralogists Foliation is any penetrative planar fabric present in rocks. Foliation is common to rocks affected by regional metamorphic compression typical of orogenic A crystal system is a category of Space groups which characterize Symmetry of structures in three dimensions with Translational symmetry in three directions In Crystallography, the hexagonal is one of the 7 Crystal system, it contains 7 Point groups. Cleavage, in Mineralogy, is the tendency of crystalline materials to split along definite planes creating smooth surfaces of which there are several named types In the field of Mineralogy, fracture is a term used to describe the shape and texture of the surface formed when a Mineral is broken The Mohs scale of mineral hardness characterizes the scratch resistance of various Minerals through the ability of a harder material to scratch a softer material Lustre (or luster) is a description of the way light interacts with the surface of a Crystal, rock, or Mineral. The refractive index (or index of Refraction) of a medium is a measure for how much the speed of light (or other waves such as sound waves is reduced inside the medium Pleochroism is an Optical phenomenon in which grains of a rock appear to be different colors when observed at different angles under a Petrographic microscope. The streak (also called powder color) of a Mineral is the Color of the powder produced when it is dragged across an unweathered surface The density of a material is defined as its Mass per unit Volume: \rho = \frac{m}{V} Different materials usually have different 09–2. 23 g/cm³
Solubility	Molten Ni

The mineral graphite, as with diamond and fullerene, is one of the allotropes of carbon. Solubility is the characteristic Physical property referring to the ability of a given substance the Solute, to dissolve in a Solvent. A mineral is a naturally occurring substance formed through geological processes that has a characteristic chemical composition a highly ordered atomic structure and specific In Mineralogy, diamond is the allotrope of carbon where the carbon atoms are arranged in "C60" and "C-60" redirect here For other uses see C60 (disambiguation. This is a list of the Allotropes of Carbon. Diamond See also Diamond Diamond is one of the best known allotropes It was named by Abraham Gottlob Werner in 1789 from the Greek γραφειν (graphein): "to draw/write", for its use in pencils, where it is commonly called lead, as distinguished from the actual metallic element lead. Abraham Gottlob Werner ( September 25, 1749 &ndash June 30, 1817) was a German Geologist who set out a now obsolete theory Greek (el ελληνική γλώσσα or simply el ελληνικά — "Hellenic" is an Indo-European language, spoken today by 15-22 million people mainly A pencil is a Writing or Drawing instrument consisting of a thin stick of Pigment (usually Graphite, but can also be coloured pigment or Characteristics Lead has a dull luster and is a dense, Ductile, very soft highly Unlike diamond, graphite is an electrical conductor, and can be used, for instance, in the electrodes of an arc lamp. In Science and engineering, a conductor is a material which contains movable Electric charges. An electrode is an Electrical conductor used to make contact with a nonmetallic part of a circuit (e Graphite holds the distinction of being the most stable form of carbon under standard conditions. In Physical sciences standard conditions for temperature and pressure are Standard sets of conditions for experimental measurements to allow comparisons to be made Therefore, it is used in thermochemistry as the standard state for defining the heat of formation of carbon compounds. In Chemistry, the standard state of a material is its state at 1 bar (100 Kilopascals exactly The standard enthalpy of formation or "standard heat of formation" of a compound is the change of Enthalpy that accompanies the formation of 1 mole of a Graphite may be considered the highest grade of coal, just above anthracite and alternatively called meta-anthracite, although it is not normally used as fuel because it is hard to ignite. Anthracite ( Greek Ανθρακίτης literally "a type of coal" from Anthrax, coal is a hard compact variety of mineral Coal that has a high

There are three principal types of natural graphite, each occurring in different types of ore deposit: (1) Crystalline flake graphite (or flake graphite for short) occurs as isolated, flat, plate-like particles with hexagonal edges if unbroken and when broken the edges can be irregular or angular; (2) Amorphous graphite occurs as fine particles and is the result of thermal metamorphism of coal, the last stage of coalification, and is sometimes called meta-anthracite. Very fine flake graphite is sometimes called amorphous in the trade; (3) Lump graphite (also called vein graphite) occurs in fissure veins or fractures and appears as massive platy intergrowths of fibrous or acicular crystalline aggregates, and is probably hydrothermal in origin.

The name "graphite fiber" is also sometimes used to refer to carbon fibre or carbon fibre reinforced plastic. Carbon fiber reinforced plastic ( CFRP or CRP) is a very strong light and expensive Composite material or fiber reinforced plastic.

Occurrence

Graphite ore

Graphite output in 2005

Minerals associated with graphite include quartz, calcite, micas, iron meteorites, and tourmalines. Quartz (from German) is the most abundant Mineral in the Earth 's Continental crust (although Feldspar is more common in Calcite is a carbonate mineral and the most stable polymorph of Calcium carbonate ( Ca[[carbon C]] O 3 The word "mica" is thought to be derived from the Latin word la micare, "glitteren" in reference to the brilliant appearance of this mineral (especially Iron (ˈаɪɚn is a Chemical element with the symbol Fe (ferrum and Atomic number 26 A meteorite is a natural object originating in Outer space that survives an impact with the Earth 's surface Tourmaline is a Crystal Silicate mineral compounded with elements such as Aluminium, Iron, Magnesium, Sodium, Lithium China is usually the top producer of graphite, followed by India and Brazil.

Graphite has various other characteristics. Thin flakes are flexible but inelastic, the mineral can leave black marks on hands and paper, it conducts electricity, and displays superlubricity. Superlubricity is a Regime of motion in which Friction vanishes or very nearly vanishes Its best field indicators are softness, luster, density and streak.

According to the USGS, world production of natural graphite in 2006 was 1. The United States Geological Survey ( USGS) is a scientific agency of the United States government. 03 million tonnes and in 2005 was 1. 04 million tonnes (revised), of which the following major exporters produced: China produced 720,000 tonnes in both 2006 and 2005, Brazil 75,600 tonnes in 2006 and 75,515 tonnes in 2005 (revised), Canada 28,000 tonnes in both years, and Mexico (amorphous) 12,500 tonnes in 2006 and 12,357 tonnes in 2005 (revised). In addition, there are two specialist producers: Sri Lanka produced 3,200 tonnes in 2006 and 3,000 tonnes in 2005 of lump or vein graphite, and Madagascar produced 15,000 tonnes in both years, a large portion of it "crucible grade" or very large flake graphite. Some other producers produce very small amounts of "crucible grade".

According to the USGS, U. The United States Geological Survey ( USGS) is a scientific agency of the United States government. S. (synthetic) graphite electrode production in 2006 was 132,000 tonnes valued at $495 million and in 2005 was 146,000 tonnes valued at $391 million, and high-modulus graphite (carbon) fiber production in 2006 was 8,160 tonnes valued at $172 million and in 2005 was 7,020 tonnes valued at $134 million.

graphite's unit cell

ball-and-stick model of a graphite layer

side view of layer stacking

plane view of layer stacking

Detailed properties

The two known forms of graphite, alpha (hexagonal) and beta (rhombohedral), have very similar physical properties (except that the graphene layers stack slightly differently). In Mineralogy and Crystallography, a crystal structure is a unique arrangement of Atoms in a Crystal. Ball-and-stick models and Space-filling models (also known as Calotte models) are 3D or spatial Molecular models which serve to display the structure See also Rhombohedral - Crystal system Graphene is a one-atom-thick planar sheet of sp2-bonded Carbon atoms that are densely packed in a honeycomb crystal lattice ^[1] The hexagonal graphite may be either flat or buckled. ^[2] Another form called cubic might have also been discovered. ^[3] Graphites that naturally occur have been found to contain up to 30% of the beta form, when synthetically-produced graphite only contains the alpha form. The alpha form can be converted to the beta form through mechanical treatment and the beta form reverts to the alpha form when it is heated above 1000 °C. The Celsius Temperature scale was previously known as the centigrade scale. The acoustic and thermal properties of graphite are highly anisotropic, since phonons propagate very quickly along the tightly-bound planes, but are slower to travel from one plane to another. Acoustics is the interdisciplinary science that deals with the study of Sound, Ultrasound and Infrasound (all mechanical waves in gases liquids and solids A thermal column (or thermal) is a column of rising Air in the lower altitudes of the Earth's atmosphere. Anisotropy (pronounced with stress on the third syllable ˌænaɪˈsɒtrəpi is the property of being directionally dependent as opposed to Isotropy, which means homogeneity In Physics, a phonon is a quantized mode of vibration occurring in a rigid crystal lattice, such as the Atomic lattice of a Solid

Graphite can conduct electricity due to the vast electron delocalization within the carbon layers. Electrical conduction is the movement of electrically charged particles through a Transmission medium ( Electrical conductor) The electron is a fundamental Subatomic particle that was identified and assigned the negative charge in 1897 by J In chemistry delocalized electrons are Electrons in a Molecule that are not associated with a single Atom or to a Covalent bond. These valence electrons are free to move, so are able to conduct electricity. However, the electricity is only conducted within the plane of the layers.

Graphite and graphite powder is valued in industrial applications for its self-lubricating and dry lubricating properties. A lubricant (sometimes referred to as a "Lube" is a substance (often a liquid introduced between two moving surfaces to reduce the Friction between them improving There is a common belief that graphite's lubricating properties are solely due to the loose interlamellar coupling between sheets in the structure. Cleavage, in Mineralogy, is the tendency of crystalline materials to split along definite planes creating smooth surfaces of which there are several named types However, it has been shown that in a vacuum environment (such as in technologies for use in space), graphite is a very poor lubricant. This vacuum means "absence of matter" or "an empty area or space" for the cleaning appliance see Vacuum cleaner. Outer space, often simply called space, comprises the relatively empty regions of the Universe outside the escape velocities of Celestial bodies. This observation led to the discovery that the lubrication is due to the presence of fluids between the layers, such as air and water, which are naturally adsorbed from the environment. Adsorption is a process that occurs when a gas or liquid Solute accumulates on the surface of a solid or a liquid (adsorbent forming a film of molecules or atoms (the This molecular property is unlike other layered, dry lubricants such as molybdenum disulfide. Molybdenum disulfide is the inorganic compound with the formula MoS2 Recent studies suggest that an effect called superlubricity can also account for graphite's lubricating properties. Superlubricity is a Regime of motion in which Friction vanishes or very nearly vanishes The use of graphite is limited by its tendency to facilitate pitting corrosion in some stainless steels, and to promote galvanic corrosion between dissimilar metals (due to its electrical conductivity). Pitting corrosion, or pitting, is a form of extremely localized Corrosion that leads to the creation of small holes in the metal In Metallurgy, stainless steel is defined as a Steel Alloy with a minimum of 11 Corrosion means the breaking down of essential properties in a material due to Chemical reactions with its surroundings It is also corrosive to aluminium in presence of moisture. For this reason, the US Air Force banned its use as a lubricant in aluminium aircraft ^[4], and discouraged its use in aluminium-containing automatic weapons ^[5]. Even graphite pencil marks on aluminium parts may facilitate corrosion ^[6]. A pencil is a Writing or Drawing instrument consisting of a thin stick of Pigment (usually Graphite, but can also be coloured pigment or Another high-temperature lubricant, hexagonal boron nitride, has the same molecular structure as graphite. Boron nitride ( BN) is a binary chemical compound, consisting of equal numbers of Boron and Nitrogen atoms It is sometimes called white graphite, due to its similar properties.

When a large number of crystallographic defects binds these planes together, graphite loses its lubrication properties and becomes what is known as pyrolytic carbon. Pyrolytic carbon is a Material similar to Graphite, but with some Covalent bonding between its Graphene sheets as a result of imperfections This material is useful for blood-contacting implants such as prosthetic heart valves. In Medicine, a prosthesis (plural prostheses) is an Artificial extension that replaces a missing Body part. In Anatomy, the heart valves are Valves in the Heart that maintain the unidirectional flow of blood by opening and closing depending on the difference It is also highly diamagnetic, thus it will float in mid-air above a strong magnet. Diamagnetism is the property of an object which causes it to create a magnetic field in opposition of an externally applied Magnetic field, thus causing a repulsive effect

Graphite forms intercalation compounds with some metals and small molecules. Potassium-graphite-xtal-3D-SF-Bpng|thumb|Space-filling model of potassium graphite (top view]] Graphite intercalation compounds are intercalation compounds with a Graphite In these compounds, the host molecule or atom gets "sandwiched" between the graphite layers, resulting in compounds with variable stoichiometry. A prominent example of an intercalation compound is potassium graphite, denoted by the formula KC₈.

Natural and crystalline graphites are not often used in pure form as structural materials, due to their shear-planes, brittleness and inconsistent mechanical properties.

History

Some time before 1565 (some sources say as early as 1500), an enormous deposit of graphite was discovered on the approach to Grey Knotts from the hamlet of Seathwaite near Borrowdale parish, Cumbria, England, which the locals found very useful for marking sheep. Grey Knotts is a Fell in the English Lake District, it is situated one kilometre south of the B5289 road as it crosses the Honister Pass Seathwaite is a hamlet in the Borrowdale valley in the Lake District of Cumbria, North West England. Borrowdale is a valley in the English Lake District in Cumbria, England. Boundaries and divisions Cumbria is neighboured by Northumberland, County Durham, North Yorkshire, Lancashire, and the Lieutenancy ^[7][8] This particular deposit of graphite was extremely pure and solid, and could easily be sawn into sticks. This remains the only deposit of graphite found in this solid form. ^[9]

Uses of natural graphite

According to the USGS, U. The United States Geological Survey ( USGS) is a scientific agency of the United States government. S. consumption of natural graphite in 2005-06 averaged 41,850 tonnes in end uses such as refractories, steelmaking, expanded graphite, brake linings, and foundry facings-lubricants. GAN (Graphite Advocate News) import-export statistics for 2006 and 2007 indicate the consumption will continue at that level unless steelmaking carbon raiser takes a drastic drop.

Refractories

This end-use begins before 1900 with the graphite crucible used to hold molten metal; this is now a minor part of refractories. A crucible is a cup-shaped piece of laboratory object Laboratory equipment used to contain Chemical compounds when heating them to very high Temperatures A refractory is a material that retains its strength at high Temperatures ASTM C71 defines refractories as "non-metallic materials having those chemical and physical In the mid 1980s, the carbon-magnesite brick became important, and a bit later the alumina-graphite shape. Currently the order of importance is alumina-graphite shapes, carbon-magnesite brick, monolithics (gunning and ramming mixes), and then crucibles. Crucibles began using very large flake graphite, and carbon-magnesite brick requiring not quite so large flake graphite; for these and others there is now much more flexibility in size of flake required, and amorphous graphite is no longer restricted to low-end refractories. Alumina-graphite shapes are used as continuous casting ware, such as nozzles and troughs, to convey the molten steel from ladle to mould, and carbon magnesite bricks line steel converters and electric arc furnaces to withstand extreme temperatures. High-purity monolithics are often used as a continuous furnace lining instead of the carbon-magnesite bricks. The U. S. and European refractories industry had a crisis in 2000-2003, with an indifferent market for steel and a declining refractory consumption per tonne of steel underlying firm buyouts and many plant closings. Many of the plant closings resulted from the RHI acquisition of Harbison-Walker Refractories; some plants had their equipment auctioned off. Since much of the lost capacity was for carbon-magnesite brick, graphite consumption within refractories area moved towards alumina-graphite shapes and monolithics, and away from the brick. The major source of carbon-magnesite brick is now imports from China. Almost all of the above refractories are used to make steel and account for 75% of refractory consumption; the rest is used by a variety of industries, such as cement. According to the USGS, 2006 U. The United States Geological Survey ( USGS) is a scientific agency of the United States government. S. natural graphite consumption in refractories was 11,000 tonnes and in 2005 11,800 tonnes.

Steelmaking

Natural graphite in this end use mostly goes into carbon raising in molten steel, although it can be used to lubricate the dies used to extrude hot steel. Supplying carbon raiser is very competitive, therefore subject to cut-throat pricing from alternatives such as synthetic graphite powder, petroleum coke, and other forms of carbon. A carbon raiser is added to increase the carbon content of the steel to the specified level. A GAN consumption estimate based on USGS U. The United States Geological Survey ( USGS) is a scientific agency of the United States government. S. graphite consumption statistics indicates that 10,500 tonnes was used in this fashion in 2005.

Expanded graphite

Expanded graphite is made by immersing natural flake graphite in a bath of chromic acid, then concentrated sulfuric acid, which forces the crystal lattice planes apart, thus expanding the graphite. Chromic acid generally refers to a collection of compounds generated by the acidification of solutions containing Chromate and Dichromate anions or the Sulfuric (or sulphuric acid, H 2 S[[oxygen O]]4 is a strong Mineral acid. The expanded graphite can be used to make graphite foil or used directly as "hot top" compound to insulate molten metal in a ladle or red-hot steel ingots and decrease heat loss, or as firestops fitted around a fire door or in sheet metal collars surrounding plastic pipe, (During a fire, the graphite expands and chars to resist fire penetration and spread. A firestop is a Passive fire protection System of various components used to seal openings and joints in fire-resistance rated wall A fire door is a type of Door, or barrier used as a Passive fire protection item within Buildings to prevent the spread of Fire or ), or to make high-performance gasket material for high-temperature use. After being made into graphite foil, the foil is machined and assembled into the bipolar plates in fuel cells. A fuel cell is an electrochemical conversion device It produces electricity from Fuel (on the Anode side and an oxidant (on the The foil is made into heat sinks for laptop computers which keeps them cool while saving weight, and is made into a foil laminate that can be used in valve packings or made into gaskets. A laptop computer, also known as a notebook computer, is a small Personal computer designed for mobile use. Old-style packings are now a minor member of this grouping: fine flake graphite in oils or greases for uses requiring heat resistance. A GAN estimate of current U. S. natural graphite consumption in this end use is 7,500 tonnes.

Brake linings

Natural amorphous and fine flake graphite are used in brake linings or brake shoes for heavier (nonautomotive) vehicles, and became important with the need to substitute for asbestos. A brake is a device for slowing or stopping the motion of a Machine or Vehicle, or alternatively a device to restrain it from starting to move again Asbestos is a group of Minerals with long thin fibrous Crystals The word "asbestos" (῾ἀσβεστος is derived from a Greek adjective This use has been important for quite some time, but nonasbestos organic (NAO) compositions are beginning to cost graphite market share. A brake-lining industry shake-out with some plant closings has not helped either, nor has an indifferent automotive market. According to the USGS, U. The United States Geological Survey ( USGS) is a scientific agency of the United States government. S. natural graphite consumption in brake linings was 6,510 tonnes in 2005.

Foundry facings and lubricants

A foundry facing or mold wash is a water-based paint of amorphous or fine flake graphite. Painting the inside of a mold with it and letting it dry leaves a fine graphite coat that will ease separation of the object cast after the hot metal has cooled. Graphite lubricants are specialty items for use at very high or very low temperatures, as a wire die extrusion lubricant, an antiseize agent, a gear lubricant for mining machinery, and to lubricate locks. A lubricant (sometimes referred to as a "Lube" is a substance (often a liquid introduced between two moving surfaces to reduce the Friction between them improving Having low-grit graphite, or even better no-grit graphite (ultra high purity), is highly desirable. It can be used as a dry powder, in water or oil, or as colloidal graphite (a permanent suspension in a liquid). An estimate based on USGS graphite consumption statistics indicates that 2,200 tonnes was used in this fashion in 2005. The United States Geological Survey ( USGS) is a scientific agency of the United States government.

Other uses

Natural graphite has found uses as the marking material ("lead") in common pencils, in zinc-carbon batteries, in electric motor brushes, and various specialized applications. A pencil is a Writing or Drawing instrument consisting of a thin stick of Pigment (usually Graphite, but can also be coloured pigment or A Zinc-carbon Dry cell or battery is packaged in a Zinc can that serves as both a container and anode An electric motor uses Electrical energy to produce Mechanical energy.

Uses of synthetic graphite

Electrodes

These electrodes carry the electricity that heats electric arc furnaces, the vast majority steel furnaces. They are made from petroleum coke after it is mixed with petroleum pitch, extruded and shaped, then baked to sinter it, and then graphitized by heating it above the temperature that converts carbon to graphite. Petroleum coke (often abbreviated petcoke) is a Carbonaceous solid derived from Oil refinery Coker units or other cracking processes They can vary in size from 6 ft. long to 6 in. in diameter. The graphite electrode market is shrinking: plasma-arc furnaces (no electrodes) are often replacing electric arc furnaces, and the electric arc furnace itself is getting more efficient and making more steel per tonne of electrode. An estimate based on USGS data indicates that graphite electrode consumption was 197,000 tonnes in 2005. The United States Geological Survey ( USGS) is a scientific agency of the United States government.

Powder and scrap

The powder is made by heating powdered petroleum coke above the temperature of graphitization, sometimes with minor modifications. Petroleum coke (often abbreviated petcoke) is a Carbonaceous solid derived from Oil refinery Coker units or other cracking processes The graphite scrap comes from pieces of unusable electrode material (in the manufacturing stage or after use) and lathe turnings, usually after crushing and sizing. Most synthetic graphite powder goes to carbon raising in steel (competing with natural graphite), with some used in batteries and brake linings. According to the USGS, U. The United States Geological Survey ( USGS) is a scientific agency of the United States government. S. synthetic graphite powder and scrap production was 95,000 tonnes in 2001 (latest data).

Other uses

Graphite (carbon) fiber and carbon nanotubes are also used in carbon fiber reinforced plastics, and in heat-resistant composites such as reinforced carbon-carbon (RCC). See also Graphene, Buckypaper Carbon nanotubes (CNTs are Allotropes of carbon with a nanostructure that can have a length-to-diameter Carbon fiber reinforced plastic ( CFRP or CRP) is a very strong light and expensive Composite material or fiber reinforced plastic. Reinforced Carbon-Carbon ( carbon-carbon or RCC) is a Composite material consisting of Carbon fiber reinforcement in a matrix of Graphite Products made from carbon fiber graphite composites include fishing rods, golf clubs,bicycle frames,and pool sticks and have been successfully employed in reinforced concrete. A fishing rod or a fishing pole is a Tool used to catch fish, usually in conjunction with the Sport of Angling, can also be used in Reinforced concrete is Concrete in which reinforcement bars (" Rebars quot or fibers have been incorporated to strengthen a material that would otherwise be The mechanical properties of carbon fiber graphite-reinforced plastic composites and grey cast iron are strongly influenced by the role of graphite in these materials. Cast iron usually refers to grey cast iron, but identifies a large group of Ferrous Alloys which solidify with a Eutectic. In this context, the term "(100%) graphite" is often loosely used to refer to a pure mixture of carbon reinforcement and resin, while the term "composite" is used for composite materials with additional ingredients. Composite materials (or composites for short are engineered Materials made from two or more constituent materials with significantly different physical or chemical

Synthetic graphite also finds use as a matrix and neutron moderator within nuclear reactors. In Nuclear engineering, a neutron moderator is a medium which reduces the velocity of Fast neutrons thereby turning them into Thermal neutrons capable This article is a subarticle of Nuclear power. A nuclear reactor is a device in which Nuclear chain reactions are initiated controlled Its low neutron cross section also recommends it for use in proposed fusion reactors. In nuclear and Particle physics, the concept of a cross section is used to express the likelihood of interaction between particles Fusion power is power generated by Nuclear fusion reactions In this kind of reaction two light atomic nuclei fuse Care must be taken that reactor-grade graphite is free of neutron absorbing materials such as boron, widely used as the seed electrode in commercial graphite deposition systems-- this caused the failure of the Germans' World War II graphite-based nuclear reactors. Boron (ˈbɔərɒn is a Chemical element with Atomic number 5 and the chemical symbol B. World War II, or the Second World War, (often abbreviated WWII) was a global military conflict which involved a majority of the world's nations, including Since they could not isolate the difficulty they were forced to use far more expensive heavy water moderators. Heavy water is water which contains a higher proportion than normal of the Isotope Deuterium, as deuterium oxide, D2O or ²H2O Graphite used for nuclear reactors is often referred to as nuclear graphite. Nuclear graphite is any of the grades of graphite usually electro-graphite specifically manufactured for use as a moderator or reflector within Nuclear reactors

Graphite has been used in at least three radar absorbent materials. Radar absorbent material, or RAM, is a class of materials used in Stealth technology to disguise a vehicle or structure from radar detection It was mixed with rubber in Sumpf and Schornsteinfeger, which were used on U-boat snorkels to reduce their radar cross section. Radar cross section (RCS is a measure of how detectable an object is with a Radar. It was also used in tiles on early F-117 Nighthawks. Modern gunpowder is coated in graphite to prevent the buildup of static charge.

Graphite mining, beneficiation, and milling

Graphite is mined around the world by both open pit and underground methods. While flake graphite and amorphous graphite are both mined open pit and underground, lump (vein) graphite is only mined underground in Sri Lanka. The open pit mines usually employ equipment (i. e. bulldozers) to scoop up the ore, which is usually put in trucks and moved to the plant. Since the original rock is usually lateritized or weathered, this amounts to moving dirt with flecks or pieces of graphite in it from the pit (blasting is seldom required). The underground graphite mines employ drilling and blasting to break up the hard rock (ore), which is then moved by mine cars pulled by a locomotive, or moved by automotive vehicles, to the surface and then to the plant. In less-developed areas of the world, the ore can be mined by pick and shovel and transported by mine cars pushed by a laborer or by women carrying baskets of ore on their heads.

Graphite usually needs beneficiation, although thick-bedded amorphous graphite and vein graphite is almost always beneficiated, if beneficiated at all, by laborers hand-picking out the pieces of gangue (rock) and hand-screening the product. The great majority of world flake graphite production is crushed and ground if necessary and beneficiated by flotation. Treating graphite by flotation encounters one big difficulty: graphite is very soft and "marks" (coats) the particles of gangue. This makes the "marked" gangue particles float off with the graphite to yield a very impure concentrate. There are two ways of obtaining a saleable concentrate or product: regrinding and floating it again and again (up to seven times) to obtain a purer and purer concentrate, or by leaching (dissolving) the gangue with hydrofluoric acid (for a silicate gangue) or hydrochloric acid (for a carbonate gangue).

In the milling process, the incoming graphite products and concentrates can be ground before being classified (sized or screened), with the coarser flake size fractions (above 8 mesh, 8 mesh to 20 mesh, 20 mesh to 50 mesh) carefully preserved, and then the carbon contents are determined. Then some standard blends can be prepared from the different fractions, each with a certain flake size distribution and carbon content. Custom blends can also be made for individual customers who want a certain flake size distribution and carbon content. If flake size is unimportant, the concentrate can be ground more freely. Typical final products include a fine powder for use as a slurry in oil drilling; in zirconium silicate, sodium silicate and isopropyl alcohol coatings for foundry molds; and a carbon raiser in the steel industry ( Synthetic graphite powder and powdered petroleum coke can also be used as carbon raiser)(Earth Metrics, 1989). West Texas PumpjackJPG|thumb|right|300px|This Pumpjack located south of Midland TX is a common sight in West Texas. Zirconium (zɚˈkoʊniəm /ˌzɝˈkoʊniəm/ is a Chemical element with the symbol Zr and Atomic number 40 For the Artificial intelligence Androids of the 1990s Science fiction series Space Above and Beyond, see Silicate (AI E550 redirects here For the Italian locomotive see FS Class E550 Sodium silicate, also known as water glass or liquid glass, available Isopropyl alcohol (also isopropanol, iso, isopro, Rubbing alcohol, or the abbreviation IPA) is a common name for A foundry is a Factory which produces Metal Castings from either Ferrous or non-ferrous alloys Steel is an Alloy consisting mostly of Iron, with a Carbon content between 0 Rough graphite is typically classified, ground, and packaged at a graphite mill; often the more complex formulations are also mixed and packaged at the mill facility. Environmental impacts from graphite mills consist of air pollution including fine particulate exposure of workers and also soil contamination from powder spillages leading to heavy metals contaminations of soil. Soil contamination is caused by the presence of man-made chemicals or other alteration in the natural soil environment Dust masks are normally worn by workers during the production process to avoid worker exposure to the fine airborne graphite and zircon silicate. Zircon is a Mineral belonging to the group of nesosilicates. Its chemical name is Zirconium silicate and its corresponding chemical formula is

Graphite recycling

The most common way graphite is recycled occurs when synthetic graphite electrodes (or anodes or cathodes) are either manufactured and pieces are cut off or lathe turnings are discarded, or the electrode (or other) are used all the way down to the electrode holder. A new electrode replaces the old one , but a sizeable piece of the old electrode remains. This is crushed and sized, and the resulting graphite powder is mostly used to raise the carbon content of molten steel. Graphite-containing refractories are sometimes also recycled , but often not because of their graphite: the largest-volume items, such as carbon-magnesite bricks that contain only 15%-25% graphite, usually contain too little graphite. However, some recycled carbon-magnesite brick is used as the basis for furnace repair materials, and also crushed carbon-magnesite brick is used in slag conditioners. While crucibles have a high graphite content, the volume of crucibles used and then recycled is very small.

A high-quality flake graphite product that closely resembles natural flake graphite can be made from steelmaking kish. Kish is a large-volume near-molten waste skimmed from the molten iron feed to a basic oxygen furnace, and is a mix of graphite (precipitated out of the supersaturated iron), lime-rich slag, and some iron. The iron is recycled on site, so what is left is a mixture of graphite and slag. The best recovery process uses hydraulic classification (Which utilizes a flow of water to separate minerals by specific gravity: graphite is light and settles nearly last. ) to get a 70% graphite rough concentrate. Leaching this concentrate with hydrochloric acid gives a 95% graphite product with a flake size ranging from 10 mesh down.

Media

See also

References

• C. Michael Hogan, Marc Papineau et al. , Phase I Environmental Site Assessment, Asbury Graphite Mill, 2426-2500 Kirkham Street, Oakland, California, Earth Metrics report 10292. A Phase I Environmental Site Assessment is a report prepared for a real estate holding which identifies potential or existing environmental contamination liabilities. 001, December 18, 1989
• Klein, Cornelis and Cornelius S. Hurlbut, Jr. (1985) Manual of Mineralogy: after Dana 20^th ed. ISBN 0-471-80580-7
• Taylor, Harold A. , "Graphite", Financial Times Executive Commodity Reports (London: Mining Journal Books ltd. ) 2000 ISBN 1-84083-332-7
• Taylor, Harold A. , "Graphite", Industrial Minerals and Rocks, 7th ed. (Littleton, CO AIME-Society of Mining Engineers) 2005 ISBN 0-87335-233-5

External links

• The Graphite Page
• Mineral galleries
• Webmineral
• Mindat w/ locations
• giant covalent structures
• USGS 2005 Minerals Yearbook: Graphite
• USGS 2006 Minerals Yearbook: Graphite
• Graphite Statistics and Information - United States Geological Survey minerals information for graphite
• Link to 'Graphite - a New Twist' - Video lecture by Prof. Malcolm Heggie, University of Sussex.