Chapter 25: Metals and Metallurgy

==Metallurgy:== all process associated with mining, separating, and refining metals and the subsequent production of pure metals and mixtures of metals

@@Metals:@@ opaque, good conductors of heat and electricity, and high malleability and ductility, generally don’t occur naturally in earth’s crust

Great thermal conductivity as a result of electrons being able to move freely and easily in pool shared by other atoms

%%Minerals:%% homogenous, naturally occurring, crystalline, inorganic solids

^^Ore^^: a rock with a high concentration of a specific mineral

==Extractive Metallurgy==: the elemental metal is extracted from the metal-containing compound in which it is found

@@Refining:@@ where the crude metal material is purified

Metallurgical Process:

1. Crush ore into small particles called ($Gangue:$ undesirable material separated from mineral-containing particles) can be separated with magnets or solution depending on the metal
2. Elemental metal is extracted from the mineral using

   A. %%Pyrometallurgy%%: heat employed to extract metal from its mineral either by use of

1. (^^Calcination:^^ heating of an ore in order to decompose it and drive off volatile product) or
2. (==Roasting:== heating that causes a chemical reaction between the furnace atmosphere gases and the mineral) or
3. (@@Smelting:@@ when roasting forms a liquid product) and a
4. ($Flux:$ material that reacts with gangue to form a substance with a low melting point) then holes tapped at different heights in material to allow
5. (%%Slag:%% silicate waste liquid material that forms from the flux and the gangue) to flow out, leaving the denser liquid metal

   B. ^^Hydrometallurgy:^^ the use of an aqueous solution to extract metals from their ore

1. ==Leaching:== gold can be separated out of a mixture by selectively dissolving it into solution

   C. @@Electrometallurgy@@: electrolysis is used to produce metals from their components

1. the hall process is the process crucial to aluminum production by reducing aluminum ions
2. sludge at the bottom of the cell in electrolysis often has precious metals

   D. $Powder Metallurgy:$ used to make metallic components from powdered metal

1. using powder avoids need for high temp heating

%%Alloy:%% metallic material containing more than one element. Either two or more metals or a metal and a nonmetal

1. ^^Substitutional Alloy^^: one metal atom substitutes for another in the crystal structure (can stay the same after substitution or differ to accommodate difference in atoms
2. I==nterstitial Alloy:== small, nonmetallic atoms fit in between metallic atoms of a crystal, formed when small nonmetallic atoms fit within octahedral/tetrahedral holes of crystalline lattice

1. @@Octahedral Hole:@@ hole between atoms in the crystalline lattice located directly above the center of the three closest packed metal atoms
2. $Tetrahedral Hole:$ forms directly above the center point of the three closest packed metal atoms in one plane and below a fourth metal atom located directly above the center point

%%Two Phase Region:%% region between two phases of alloys on the graph where the alloy is in both or either phase at once

^^Lever Rule:^^ states that in a two-phase diagram, whichever phase is closer to the composition of the alloy is the more abundant phase

Titanium

9th most abundant, coal ash, magnetic, very reactive, resistant to corrosion because it forms an oxide coating with air, strong and light

==Arc Melted:== a solid metal is melted with an electrical discharge from a high voltage electric source in a controlled atmosphere to prevent oxidation-then collected in a cooled copper pot

Chromium

Different compounds brightly colored, metallic Cr is white, hard, lustrous, brittle, easily dissolving in acid except nitric, toxic and potentially carcinogenic

Manganese

Very reactive, dissolves in most metals, added to glass to decolorize

Cobalt

Found within ores of other metals, very strong and hard, brightly colored

@@Ferromagnetic:@@ atoms that contain unpaired electrons which can align with their spins oriented in the same direction, creating a permanent magnetic field

Copper

Very economical, high electrical conductivity, not very strong

$Bronze:$ copper and tin alloy which is stronger and resists wear and corrosion better than pure copper

%%Brass:%% copper and zinc alloy

Nickel

Nickel carbonyl can be heated past 200 degrees Celsius to decompose into nickel metal and CO called Mond Process. Fairly unreactive, resistant to corrosion, good for protective coatings

Zinc

Alloys include German or Silver brass from zinc, silver, and copper. Can galvanize objects by dipping it in zinc