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118248
Metal Extraction
Descripción
Mapa Mental sobre Metal Extraction, creado por jasmin.sahota el 01/06/2013.
Mapa Mental por
jasmin.sahota
, actualizado hace más de 1 año
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jasmin.sahota
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Resumen del Recurso
Metal Extraction
Iron
Iron found as Fe3O4 and Fe2O3
major impurity = silica SiO2
reduction by carbon in the blast furnace
USES COKE
can produce up to 10,000 tonnes a day
they run continiously
at bottom of furnace, coke is burned in hot air
heat is generated, exothermic
temperature = 2000K
melting point = 1808K
CO2 formed which reacts with more C to form CO
C(s)+O2(g)-->CO2(g)
CO2(g)+C(s)-->2CO(g)
Carbon monoxide is the reducing agent
Fe2O3(s)+3CO(g)-->2Fe(l)+3CO2(g)
iron mixed with other element to make alloys
chromium and nickel used to make stainless steel
Manganese oxide and copper oxide
copper carbonate to copper oxide
CuCO3--> CuO+CO2
then heated WITH COKE
2CuO(s) +C(s)-->2Cu(l)+CO2(g)
now copper is converted to a solution with Cu2+ ions
done by spraying dilute acid in the presence of bacterium
copper is extracted by reduction with scrap iron
Cu2+(aq)+Fe(s)-->Cu(s)+Fe2+(aq)
economic sense as copper is more expensive than iron
scrap iron is very cheap and avaliable
no CO2 is produced
uses less energy than copper with carbon
although iron has to be extracted first, which used iron originally
Tungsten
moderately rare
abundance in the Earth's crust
used in bulb filaments
due to high melting point
because of high melting point
CANNOT BE REDUCED BY CARBON
because carbide is formed
extracted from WO3
by reduction with Hydrogen at high temp
WO3+3H2-->W+3H2O
Aluminium
ELECTROLYSIS
it is extracted from bauxite, Al2O3
oxide is dissolved in molten cryolite, Na2AlF6
melts at 1240K, compared to 2345K
electrolysed in currents of 300,000A
aluminium is produced at the negative electrode (steel casing)
(2Al3+)+(6e-)-->2Al
oxygen at the positive electrode (made of carbon)
(3O2-)-->1.5O2+6e-
overall process is the decomposition of Al2O3
Al2O3-->2Al +1.5O2
continuous, and kept molten by heat
Al is a liquid
O2 mixes with C electrode to become CO2
hence C electrode has to be replaced regularly
expensive because of the electricity needed
Ti
reduced by a more reactive metal
strong, low density and non-corrosive
relatively abundant
TiO CANNOT BE REDUCED BY CARBON
as produced Ti carbide (brittle)
reduced using sodium, or magnesium
very expensive
convert from TiO to TiCl4
by reacting with coke and chlorine
at 1173K
TiO2(s)+2C(s)_2Cl(g)-->TiCl4(l)+2CO(g)
TiCl4 is purified using distillation
reduction of TiCl4
with sodium under inert argon atmosphere at 1300K
argon is needed to prevent the metals from reacting with nitrogen and oxygen in air
TiCl4(l)+4Na(l)-->Ti(l)+4NaCla(l)
Magnesium is another reactive metal that can also be used
this is a batch process
less efficient
as has to be heated back up to operating temps after each batch is removed
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