C11 Extracting Metal Modern And Traditional Methods Flashcards
Ore
A rock that contains enough metal to make it profitable to extract it.
Profitable
You spend money to get the ore out, then sell the metal, if it is profitable you have more money after selling than before.
Native metal
A very unreactive metal that is found as a pure metal in nature (underground).
Extraction
The process of getting a pure metal from its ore.
Electrolysis
The breakdown of an ionic substance by electricity into atoms.
Reactivity series + method of extraction
Most reactive
Please-potassium>electrolysis of a molten compound
Stop - sodium —> electrolysis of a molten compound
Calling - calcium —> electrolysis of a molten compound
Me - magnesium —> electrolysis of a molten compound
A - aluminium —> electrolysis of a molten compound
Careless - (carbon)
Zebra - zinc —> heat an ore with carbon
Instead - iron —> heat an ore with carbon
Try - tin —> heat an ore with carbon
Learning - lead —> heat an ore with carbon
How - (hydrogen)
Copper —> found as the unconfined element
Saves - silver —> found as the unconfined element
Gold —> found as the unconfined element
Least reactive
How are the least reactive and next least reactive set of metals found
● The least reactive elements (platinum, gold and silver) are found as uncombed elements, that means they are found as pure metals- that’s why you can pan for gold, little chunks are washed out of the earth and dropped in river beds.
● The next set of metals, the less reactive metals (eg copper, iron and zinc) are found as compound (often metal oxides).
How are less reactive metals found?
● The ‘less reactive metals’ are extracted from the compound they are found in (their ore) by a displacement reaction, they are reacted with carbon (coal) which is more reactive and cheap in comparison to the metal.
● As most ores are metal oxides, extracting the metal is a reduction reaction.
2Fe2O3 + C → 4Fe + CO2
iron oxide + carbon → iron + carbon dioxide
When iron oxide is heated with carbon, the carbon removes the oxygen from the iron oxide.
The Iron is loosing oxygen (reduction), and the carbon is gaining oxygen (oxidation).
This still works with OIL RIG.
Iron starts as Fe3+ and becomes Fe (gain of electrons).
How are more reactive metals extracted?
Metals that are more reactive than carbon are extracted by electrolysis - see electrolysis section.
Biological methods (phytoextraction)
Phytoextraction involves growing special plants that absorb copper compounds, through their roots.
The harvested plants are burnt to form ash, from which copper is extracted by dissolving the ash and performing electrolysis.
Biological methods (bioleaching)
Bioleaching uses bacteria grown on a low grade ore (ore with a small % of the metal in it).
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.
Advantages of extracting copper using bioleaching
● no harmful gases (e.g. sulfur dioxide) are produced
● causes less damage to the landscape than mining
● conserves supplies of ores containing high percentages of metal compounds
● does not need a high temperature
