Geochemically Common metals

 

For information and statistics on many metallic and non-metallic resources, check out the mineral commodity summaries on the US Geological Survey web site at http://minerals.usgs.gov/minerals/pubs/mcs  

 

Iron, Steel and Ferro-Alloy metals

 

 

Properties and use

 

Steel is the backbone of industry and most abundant metal used

Steel is iron (Fe) with a small amount of carbon – varying carbon content changes properties.  Pure iron is fairly soft, adding carbon improves hardness and resilience.  Also adding other metals produce steel alloys that have desirable properties – eg. addition of chromium or nickel produces stainless steel

 

 

Ore deposits and mining

Magnetite, hematite, goethite main ore minerals

 

Mafic igneous rocks

Residual deposits, including laterites

 

Sedimentary deposits

Ironstones – Phanerozoic (less than 500 million years old)type (=Minette=Clinton=Wabana type)

Banded Iron Formations - BIFs (Lake Superior type – taconites in North America) 20-40% Fe

 Occur in Precambrian rocks 2600-1800 million years ago when atmosphere was more reducing than at present  (thus, iron more soluble)

 

 

 

Processing

Two stage:

Blast furnace to produce pig iron (high carbon content)

Conversion to extract carbon

 

 

Production and producers

Original production in Europe, but by late 19thC US dominant in steel production.  World steel production continued (infrastructure), slack in Depression.  European industries wiped out in WW2.  By 1950 US pre-eminent (almost 50% or world production).

 

Later Japan rebounded with newer, more efficient plant, US declined  to only 12% at present.  Russia, China, India, South Korea also major players.

 

 

China, Brazil, Australia the main producers  also Russia, India

Australia, Russia, Ukraine greatest in reserves

 

Future trends

Recycling a major trend – about 40% recycled in US

 

 

Ferro-alloy metals

 

Certain metals major use is as alloy material to give steel various properties

 

Manganese – removes O and S, improves wear resistance;  most important ferro-alloy metal 7kg for each tonne of steel produced.

 

Chromium  - high temperature strength, corrosion resistance;  chromite – Bushveld Complex, South Africa

 

Nickel – low temp strength, corrosion resistance;  tropical laterites – Dominican Republic, Cuba

 

Cobalt – high temp hardness

 

Titanium  - toughness, grain size control; oxide used as paint pigment; mined in N Florida

 

Tungsten - high temp hardness

 

Vanadium - high temp hardness

 

 

Aluminum (Al)

 

 

Properties and use

.  Ductile therefore easily made into  useful objects such as consumer durables.  Good electrical and thermal conductivity.  Resistant to corrosion. High strength to weight ratio, because of low density – autos and aircraft.

 

Not produced widely until 20thC because difficult to separate metal from ore.  Pyrometallugical processes cannot be used.

 

Ore deposits and mining

Usually strip mining

 

Processing

gibbsite+boehmite+diaspore (all hydroxides) = bauxite

Bauxite is a residual deposit formed in tropical climates. percolating water removes everything from soil except Al hydroxides and Fe oxides (hence most bauxites are red or brown).  Soil may be eroded and redeposted to form placer deposits.

 

Alumina (Al-oxide) first produced from bauxite on site.   Uses strong alkali  sodium hydroxide. 

 

This alumina  then usually shipped to smelting site.  Large amounts of electrical energy used in electrolystic process. Therefore expensive to produce. Usually sites with abundant  hydroelectric power – Canada, Sweden. 

 

Production and producers

Aluminum

Australia, Guinea, Jamaica, Suriname/Guyana

 

 

Future trends

 

Because of energy intense production, concern is more about that than reserves of ore.  Therefore, recycling (30% at present) is important.

 

 

Silicon

 

Properties and use

Second most a element in the Earth’s crust, strongly bound to oxgen.

Pure metal is light weight, silvery and very brittle.

Ferrosilicon  used in steel production.

Silicon carbide (a.ka. carborundum) hardnesssecond only to diamond

Semiconductors

 

 

Ore deposits and mining

Pure quartz the best material – usually vein quartz

 

Processing

quartz + scrap iron melted together to form ferro-silicon.  Quartz a very common mineral.

 

 

Production and producers

Large power requirements for refining mean that like aluminum, countries with cheap hydro electric power will be major producers.  Norway, China.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Properties and use

 

 

 

Ore deposits and mining

 

 

Processing

 

 

 

Production and producers