t10- extracting metals and corrosion Flashcards
what are the 4 ores and the metals
malachite-copper
haemite-iron
magnitite- iron
bauxite-aluminium
what is an ore
a naturally occurring substance where a metal can be extracted profitably
what are high/low grade ores
high grade ores contain lots of the mineral with low impurities
low grade ores contain little of the mineral with high impurities
what is phytomining
-plants are grown on ore
-plants are burnt to produce ash
-ash is dissolved in acid to produce solution of the metal compound
-solution is electrolysed
advantages of phytomining
-reduces need for mining
-conserves limited supplies of high grade ores
disadvantages of phytomining
-land not available
-slow
new technology
-high grade ores are still available
what is bioleaching
-bacteria break down low grade ores to produce an acidic solution containing the mineral
advantages of bioleaching
-doesn’t need high temp
dissadvantage of bioleaching
produces toxic substances, including sulfuric acid, which damage the environment.
4 advantages of recycling
-fewer quarries/mines to extract finite reserves of metal ores
-less crude oil extracted for plastics
-less energy needed compared to making new product- greenhouse gas emissions reduced
-waste in landfills reduced
what is corrosion
metals are slowly broken down by reacting with substances in their environment
equation for rusting
iron+water+oxygen->hydrated iron(lll) oxide
why does only the surface corrode on aluminium (+other metals)
only the surface atoms are affected
-aluminium is oxidised which forms a protective layer so the rest of the metal can’t corrode
what is the sacrificial method of prevention
adding a more reactive metal to iron
-it will be oxidised instead
what are barrier methods of prevention
-paint
-oil/grease
-electroplating: using electrolysis to create a thin layer of another metal
