Topic 8: Metals Flashcards
What is a metal? its characteristics
- element, compound, or alloy
- good conductors of heat and electricity
- malleable, ductile, shiny
- form cations through electron loss
What are native metals?
- metals occurring in the crust in its metallic “pure” form
- copper, silver, gold are the main elements that are found as native metals
What are available metals?
- any kind of metal found in the crust, usually found with other metallic elements, available thru mining and smelting
- found as abundant or scarce metals
what are alloys?
- chemical mixtures of 2 or more metals
- superior strength, durability, corrosion resistance
What are ores?
- metals found in crust with low concentrations
- mixed with other stuff
-can be concentrated under certain geological or geodynamic processes - to be considered an ore deposit, concentrations must be legally, technically, and economically extractable
what are some abundant metals?
- iron
- manganese
- aluminum
- titanium
- magnesium
What metals do we use the most? Why?
- iron
- very strong and durable, ease of smelting and processing
- very common to find, abundant and available and has a low cost
What do we use iron form?
- construction, transportation, machinery
What ores are economically extractable for the purpose of iron?
- oxides: hematite, magnetite, goethite
- sulphides: pyrite
where is iron found in contact metamorphic deposits?
- in skarn-like deposits
- iron-rich hydrothermal fluids excluded from cooling igneous intrusions, react with adjacent rocks
where is iron found in ignenous sources underwater?
- in seafloor volcanism, submarine hydrothermal activity
- black smokers! solutions of iron and silica
What are some sedimentary sources of iron?
- bog iron
- ironstones
- banded iron formations
What are banded iron formations?
-BIFS supply majority of our global iron production, contain 20-40% iron
- present in Precambrian rocks
- rocks that literally have bands of alternating iron oxide and silica
- iron sources come from weathering in the absence of oxygen
How can iron be mined?
- small scale, local extraction of iron stone
- commercial scale, open pit mining of iron deposits close to surface
What is benefication?
the enrichment of an ore prior to smelting
What are the different kind of steels made with iron?
- carbon steels (iron+carbon)
- alloy steels (iron+other elements like silicon, nickel..)
- stainless steels (iron+ chromium)
What is manganese used for?
- added to iron smelting to scavenge sulphur and oxygen
- using in water treatment, and dry cell batteries
Manganese is precipitated as ore minerals such as…
- pyrolusite
- psilomelane
- romanechite
- rhofochrosite
What is the second most abundant metallic element in the crust?
Aluminum
the main ore for aluminum is..
bauxite, which contains gibbsite and boehmite and diaspore
how is bauxite formed?
- by advanced chemical weathering of aluminum rich rocks, in wet tropical conditions
Where is aluminium NOT found on earth? why?
- arctic areas
- due to cold and glacial erosion
titanium is the ___ common abundant metal
LEAST
What are the main ores of titanium
ilmenite and rutile
What is magnesium used for
- as refractories
- as alloys (mixed with aluminum)
- used in cement fertilizers, paper, ect
What are scarce metals?
- metals of low crustal abundance, <0.1% crustal abundance
- ferro-alloy metals, base metals, precious metals, special metals, etc
what are ferro-alloy metals?
- type of scare metals
- used in additives in specialty steels to change physial/chem/electrical properties
- eg chromium, vanadium, nickel, molybdenum
What is chromium?
- a ferro-alloy scarce metal
- used in tanning and pigments
- also used in stainless steel
What is vanadium?
- a ferro-alloy scarce metal
- used in leather tanning, pigments
- used in the oil and gas industry
What is nickel?
- a ferro-alloy scarce metal
- used in household utensils, electroplating, coins, corrosion resistence, vehicles
what us molybdenum?
- a ferro-alloy scarce metal
- used in armour plating, tool steel, lubricants, pigments, catalysts
What is cobalt?
- a ferro-alloy scarce metal
- used in blue pigments, as an alloy, in jet engines, rockets, gas turbines
- occurs as a by-product of mining and processing copper, nickel, and silver ores
What is tungsten?
- a ferro-alloy scarce metal
- used as a steel alloy, in drill bits, cutting edges, weapons, bulbs and heating elements
What are base metals?
- scarce metals that are cheaper and typically more abundant than ferro-alloys
- not as resistant to corrosion
- but used in alloys, coinage, manufacturing, etc
- copper, tin, lead, zinc, cadmium, etc
what are some base metal alloys?
- bronze (copper and tin), pewter (tin and lead), brass (copper and zinc)
What is copper
- a base metal
- used lots in prehistoric times, very malleable and easily smelted
- used in alloys, for weapons, tools, pipes, etc.
- greatest used is in electrical distribution
What ores is copper present in?
- chalcopyrite
- digenite
- chalcocite
- bornite
- enargite
- azurite
- malachite
How are copper oxide ores processed?
- solvent extraction electrowinning
- essentially heap leaching
- crushed copper ores leached with acid, acid dissolved copper then treated with electrolysis to release pure copper
What kind of deposits are copper ores found in?
- magmatic segregation deposits
- hydrothermal deposits
- porphyry copper deposits
- skarn type contact metamorphic deposits
- volcanogenic massive sulpide deposits
What are lead and zinc?
- base scarce metals
- commonly occur together and rarely in their native state
- lead used in weights, sheet metal, ceramics
- zinc used in galvanizing, coinage, sunblock and pigments
what kind of deposits are lead and zinc found in?
- hydrothermal vein deposits
- volcanogenic massive sulphide deposits
- mississippi valley type deposit
- sediment-hosts stratiform deposits
What is tin?
- scarce base metal
- used since prehistory
- typically was used as an alloy with copper to make bronze
- cassiterite is a main tin ore
Where are tin ores found?
- granitic pegmatites
- volcanic hydrothermal deposits (porphyrys)
- also stanniferous placer deposits
What is Mercury?
- scarce base metal
- liquid at room temperature
- easily forms alloys and amalgams
- main ore in cinnabar
- found in hydrothermal vein deposits
- toxic, is now a controlled substance
What is mercury used in? Currently and formerly
- currently used in fluorescent lights, chemical production and measuring instruments
- formerly used in thermometers, thermostats, batteries
What is cadmium?
- scarce base metal
- soft, malleable, silver-white
- pure cadmium minerals are rare, so we used atomic substitution in sphalerite to make cadmium
- all cadmium now is a byproduct of zinc production
- cadmium was used previously for corrosion resistance, similar to zinc, and also used in rechargeable batteries, pigments, etc.
- cadmium is very toxic, and is not a regulated substance
What are precious metals? name them
- gold, silver, platinum group elements
- scarce metals that have high values due to their rarity
- have been used since antiquity for decoration, investments, etc
- all are resistant to corrosion and chemical reaction
What is gold?
- scarce precious metal
- known since antiquity, very rare and commonly used for ornamental purposes and as currency.
- currently used in jewelry, electronics, dentistry, special alloys
- we produce very little gold globally every year.
Where is gold found?
- commonly found as a native metal, from hydrothermal solutions originating from granite intrusions
- typically occurs within quartz veins
- also found in lots of placer deposits (ends up in these is gold is eroded from hydrothermal deposits accumulating in stream beds due to its high density
For gold, most modern mines exploit either…
- low grade hydrothermal deposits, often associated with hot springs or low grade copper porphyry deposits
What are some of the ways that gold is/was extracted?
- density separation via gold panning
- liquid mercury added to ores or placer sediments, forms amalgam with gold, amalgam removed and then heated to vaporize mercury
- cyanide heap leaching to dissolve gold
What is silver?
- scarce precious metal
- used lots in antiquity
- modern uses are jewelry, industrial uses, photography, dentistry, etc
- typically co-occurs with copper or lead , most silver we produce is found as a by product of copper or lead mining
What are some major silver minerals?
- argentite
- tetrahedrite
What are the platinum group metals?
- scarce precious metals
- platinum, palladium, rhodium, iridium, ruthenium, osmium
- silver, white malleable metals
- all occur as native metals
- highly corrosion resistant, high melting temperatures
- can be used as catalysts to speed chemical reactions
What are the two major platinum group metal sources?
- mafic and ultramafic igneous sources; concentrated in chromite and nickel sulfides
- placer deposits; accumulate in stream deposits much like gold due to density
What are special metals?
- scarce metal group
- metals with unique properties and special roles
- Niobium, and tantalum
- arsenic, antimony, bismuth
- germanium, gallium, indium
What are niobium and tantalum?
- special metals
- occur together
- Tantalum used in capacitors, rectifiers, electronics
- niobium used in high temp steel and electrical capacitors
- found in columbite and tantalite
What are arsenic, antimony, and bismuth?
- special metals
-occur in lead, zinc, and copper ores, typically mined as byproducts
What is arsenic?
- scarce special metal
- considered a semi-metal due to brittleness
- used in wood preservation, fungicides, insecticides, pesticides
- highly toxic
What is germanium?
- scarce special metal
- used as a semi-conductor
- alloyed with silver to prevent tarnishing
What is beryllium?
- scarce special metal
- known as gemstone beryl
- very light, but stiff.
- used for x-ray equipment, nuclear weapons and reactors, semi-conductor
- highly toxic
What are rare earth elements?
- scarce special metals
- lanthanide series and related elements
