exploitation of low grade ores

• typical ore extraction involves smelting
• as ore purity decreases, energy required increases
• bioleaching involves the use of living organisms to extract metals from ores
• acidophilic bacteria: bacteria oxidise sulphide ores and produce sulfuric acid which dissolves metals
• aspergillus fungi can grow on scrap electronic components, the fungi produces acids that dissolve specific metal types
• metals in solutions can be separated by electrolysis or carbon filters
• Phyto mining: some plants have the ability to uptake and absorb metal ions from the soil or from water, this is then concentrated in their leaves
• plants involves in Phyto mining, are harvested and then burned. the metals in the ash can be dissolved using acids and then ultimately separated by electrolysis
• phytomining can be used to decontaminate polluted sites and to extract metals
• iron displacement occurs because iron is more reactive than copper, iron has the ability to displace copper ions from a solution
• leachate collection: rainwater that percolates through spoil heaps, dissolves soluble metal ions. draining leachate can be recirculated from the spoil heap to increase concentration of metal ions in the solution that is extracted
• rare earth metals are often used in small concentrations in important appliances
• rare earth metals exploitable deposits are limited
• chemical separation of rare earth metals is difficult , it often produces high concentrations of toxic wastes
• deep sea sediments of rare earth metals typically have hugher concentrations, however there are no viable methods of exploitation of these sediments yet
• polymer absorbtion: dissolved metal ions in seawater absorb onto polymer surface, thi allows it to be collected