Extracting metals Flashcards
how is gold and platinum found in the Earths crust
as uncombined elements in their native state
what is irons’ ore
haematite - iron(III) oxide
what is alumniums’ ore
bauxite - aluminium oxide
what is an ore
a rock that contains enough of a metal or a metal compound to make extracting the metal worthwhile
what are the factors contributing to the price of a metal
the abundance of the ore in the earth’s crust
the mining costs
the energy costs in the process of extracting the metal from its ore
the demand for the metal
what are the advantages of recycling metals
natural reserves of metal ores will last longer
less energy is needed to recycle metals than to extract metal from its ore
the need to mine ores is reduced
there is less waste in landfill sites
less damage to the landscape
what are some disadvantages of recycling materials
costs and energy needed to collect, transport and sort the metal
more energy needed to recycle the metal than to extract it from its ore
large amount of energy needed to melt the used metal item
why is aluminium more expensive than iron
Aluminium is produced by electrolysis of molten aluminium oxide but iron is produced by heating iron oxide with carbon
what are the reasons for recycling aluminium
it saves energy
natural reserves of bauxite will last longer
less mining of the ore
how are metals less reactive than carbon extracted from their compounds
by heating the ore with carbon
how is zinc extracted from zinc oxide using carbon
heat the zinc oxide with carbon. As carbon is more reactive than zinc it removes the oxygen from zinc oxide and reduces it to zinc
explain the process of phytoextraction
the plants absorb metal ions from the soil through the roots and they concentrate these ions in their cells. The plants are harvested and burned to leave the metal compound. Copper is extracted from the copper compound by displacement using scrap iron, then purified using electrolysis
what are the advantages of phytoextraction
it reduces the need for mining so causes less damage to the environment
it conserves supplies of higher grade ores
it can be used to extract metal pollutants from contaminated soils
no harmful gases are produced
what are the disadvantages of phytoextraction
it is a slow process
growing plants for phytoextraction is dependant on weather conditions
currently the process of phytoextraction is more expensive than mining some ores
explain the process of bioleaching
bacteria are grown on a low grade ore. The bacteria produce a solution containing copper ions called a leachate. Copper is extracted from the leachate by displacement using scrap iron, then purified by electrolysis
what are the advantages of bioleaching
it reduces the need for mining so less damage to the environment
it conserves supplies of higher grade ores
does not require high temperatures
no harmful gases
what are the disadvantages of bioleaching
it is a slow process compared to smelting
toxic substances and sulphuric acid can be produced by the process causing damage to the environment
what is recycling metals
converting used metal items into new metal that is reusable
what are the steps needed in recycling metals
collecting and transporting items to a recycling centre
breaking up and sorting the different metals
removing impurities from the metals
heating the metal to melt it and pouring it into a mould
what are the advantages of recycling metals
natural reserves of metal ores will last longer
less energy needed to recycle than extract metal from its ores
need to mine ores is reduced
less waste in landfill sites
less damage to environment
less sulfur dioxide produced
what are the stages which scientists measure the impact of
obtaining the raw materials
manufacturing and packaging the product
using the product
disposing of the product
