Metals

Concentrated enough to allow economical recovery of desired metal.

Mineral Deposit

Refers to the desired metal.

Ore

Non-economical metal.

Gangue

Main ore mineral of chromium.

Chromite

Resulting soil layer due to weathering, erosion, and soil formation, typically red in color due to the presence of iron oxides and hydroxides.

Laterite

Rich source of some metal ions such as Na+, Mg2+, and Ca2+.

Seawater

Found in vast areas of the ocean floor, made up of mostly manganese with iron, nickel, copper, and cobalt in a chemically combined state.

Manganese Nodules

Metals that show the least chemical reactivity.

Noble Metals

Force that holds atoms together in a metallic substance, formed between positively charged atoms in which the free electrons are shared among a lattice of cations.

Metallic Bond

Electron in an atom, ion, or molecule not associated with any single atom or a single covalent bond.

Delocalized Electron

Formed by delocalized electrons that are free to move throughout metals.

Sea of Electrons

Science and technology of separating metals from their ores and compounding alloys.

Metallurgical Process

Solid solution either of two or more metals or of a metal or metals with one or more nonmetals.

Alloy

Desired mineral is separated from waste materials called gangue.

Preparation of the Ore

Ore is finely ground and added to water containing oil and detergent to separate mineral particles from gangue.

Flotation

Strongly attracted to magnets.

Ferromagnetic Metals

Alloy of mercury with another metal/s.

Amalgam

Process of using mercury to dissolve silver and gold in an ore.

Amalgamation

Production of a free metal is a reduction process since metals in their combined forms always have positive oxidation numbers.

Production of Metals

May be necessary to convert the ore to a chemical state more suitable for reduction.

Preliminary Operations

Can be reduced more conveniently to yield the pure metals.

Metal Oxides

Involved in most major metallurgical processes, procedures carried out at high temperatures.

Pyrometallurgy

Can be used as a reducing agent to separate a less electropositive metal from its compound.

Electropositive Metal

Suitable for very electropositive metals such as sodium, magnesium, and aluminum, usually carried out on the anhydrous molten oxide or halide of the metal.

Electrolytic Reduction

Further treatment to remove impurities.

Purification of Metals

Applied to metals with low boiling points such as mercury, magnesium, and zinc to separate them from other metals.

Fractional Distillation

Well-known method of fractional distillation for the purification of nickel.

Mond Process

More electropositive metals are removed by an electrolysis process in which the impure metal acts as the anode and pure metal acts as the cathode.

Electrolysis

Metal rod containing a few impurities is drawn through an electrical heating coil that melts the metal.

Zone Refining

Contains from 50% to 70% iron depending on grade.

Iron Ore

Almost 70% iron.

Hematite

Supplies heat for chemical reactions and produces carbon monoxide to reduce iron ore.

Coke

Used as a flux to react with and remove impurities in molten iron.

Limestone

Used to burn coke.

Hot Gases

Mixture of calcium silicate and calcium aluminate that remains molten at the furnace temperature.

Slag

Refractory-lined chamber used for the production of iron.

Blast Furnace Process

Product of the blast furnace that contains over 4% C plus other impurities.

Pig Iron

Alloy of iron containing 0.02% and 2.11% carbon by weight, often includes other alloying elements.

Steel

Molds made of high carbon iron, used for solidification of steel.

Casting of Ingots

Reduces solidification time by pouring steel into a water-cooled continuous mold.

Continuous Casting

Furnace used for converting pig iron into gray cast iron.

Cupola

Obtained by melting the mixture of pig iron, scrap iron, and coke, has around 3% carbon content.

Cast Iron

Uses pure oxygen to burn off impurities in molten pig iron.

Basic Oxygen Furnace

Carbon is the principal alloying element, strength increases with carbon content but ductility is reduced.

Plain Carbon Steels

Contain less than 0.20%

Low Carbon Steels

range between 0.20% and 0.50% C, used in machinery components and engine parts

Medium Carbon Steels

contain carbon in amounts greater than 0.50%, used in springs, cutting tools, and wear-resistant parts

High Carbon Steels

iron-carbon alloys that contain additional alloying elements in amounts totalling less than 5% weight; mechanical properties superior to plain carbon steels

Low Alloy Steels

highly alloyed steels, typically with Cr and/or Ni, designed for corrosion resistance

Stainless Steels

typical composition is 17% Cr and 7% Ni, with additional small amounts of alloying elements

Precipitation Hardening Stainless

a mixture of austenite and ferrite in roughly equal amounts

Duplex Stainless

highly alloyed steeld designed for use as industrial cutting tools, dies, and molds. They must possess high strength, hardness, hot hardness, wear resistance, and toughness under impact.

Tool Steels

states that delocalized electrons move freely through “bands” formed by overlapping molecular orbitals

Band Theory of Electrical Conductivity

set of closely spaced empty energy levels

Conduction Band

a measure of the ability of an atom to attract electrons when the atom is part of a compound. (Increases from left to right and from bottom to top)

Electronegativity

how readily an atom can lose an electron (decreases from left to right and from bottom to top)

Metallic Property

- the distance between the nuclei of two identical atoms bonded together (increases from right to left and top to bottom)

Atomic Radius

the degree to which an atom or molecule attracts additional electrons; the minimum energy required to remove an electron from a negative ion (increases from left to right and from bottom to top)

Electron Affinity

the property of metals that makes it shiny

Metallic Luster

reflects about 90% of light falling on it

Silver

ability to resist denting from impact

Hardness

ability of metals to be hammered in to thin sheets

Malleability

the most malleable metals

Gold and Silver

ability to be drawn into thin wires

Ductility

ability to conduct electricity

Electrical Conductivity

most metals reacting with water produce hydroxide

Water reactivity

most metals react with acids to produce salts and hydrogen

Acid Reactivity

metals displace other metals in metallic compound when they have higher reactivity

Metal Displacement Reactions

the deterioration of metals by an electrochemical process like rusting of iron and tarnishing of silver

Corrosion

a greenish substance formed by copper which is copper carbonate

Platina

the surface of the iron metal is made inactive by treating it with a strong oxidizing agent such as nitric acid to form a thin oxide layer at the surface

Passivation

combining the metal with other metals to reduce its tendency to oxidize

Alloys

- applying a thin layer of other metals like tin or zinc on the surface of iron

Plating

a process in which metal that is to be protected from corrosion is made into the cathode in what amounts to a galvanic cell

Cathodic Protection

specified by a 4-digit number system YYXX, the first two numbers YY represent the alloying elements and the last two numbers XX represent the carbon % in hundredths of percentage points

Designation Scheme for Steels

three-digit AISI numbering scheme; first digit indicates the general type and the last two digits give a specific grade within type

Stainless Steel

metal elements and alloys not based on iron

Nonferrous Metals

the most electropositive elements that have a body-centered crystal structure with low packing efficiency

Alkali Metals

the lightest known metal

Lithium

second most reactive metals in the periodic table and have increasing reactivity in the higher periods

Alkaline Earth Metals

high electrical and thermal conductivity, corrosion resistance, and light

Aluminum

low electrical resistivity

Copper

copper and tin

Bronze

copper and zinc

Brass

the highest strength alloy of copper

Beryllium-Copper

steel coated with zinc

Galvanized Steel

highest melting point among metals and one of the densest , also the stiffest and hardest of all pure metals

Tungsten

high-performance alloys designated to meet demanding requirements for strength and resistance to surface degradation at high service temperatures

Superalloys

in some cases, iron is less than 50% of total composition

Iron-Based Alloys

better high temperature strength than alloy steels

Nickel-Based Alloys

40% Co and 20% Cr

Cobalt-Based Alloys

performed to enhance properties

Heat Treating

commonly used to improve the appearance of metal parts and/or to provide corrosion protection

Finishing Processes

an important technique to strengthen metals

Alloying

strain hardening during deformation to increase strength.

Cold Working

heating and cooling cycles performed on metal to beneficially change its mechanical properties

Heat Treatment

the materials is heated between 750-980 degrees Celcius then cooled at a room temperature; product: high strength and high ductility, tougher than annealed steal

Normalizing

heating above critical temperature then controlled cooling inside furnace

Annealing

heating then rapid cooling in water or oil for hardening steel

Quenching

reheating below critical temperature, holding the temperature for a specific period, then slowly cooling in still air

Tempering