Ore Mineral Security Flashcards
Copper deposits
Copper ores are found all over the world. There are different types of copper deposits, which form in different conditions. Porphyry deposits are the most common source of copper ore, followed by sedimentary deposits.
There are particularly large concentrations down the west coast of North and South America, and across Europe and Asia.
Chile
In 2014, Chile was the biggest producer of copper Porphyry copper deposits in the world, accounting for 31% of all copper mined. China had the next biggest global share with 9%.
Global copper production has increased by about 3% per year since 1900. Since 1960 Latin America and Asia have seen the most growth in copper production. Chile and Peru are continuing to invest in mines in order to continue producing enough copper to meet the demands of the major industrial nations, especially China.
Porphyry Deposits
Porphyry deposits are found in igneous rocks formed at destructive plate margins, usually where a dense oceanic plate is being forced underneath a less dense continental plate.
The continental plate melts, forming magma that contains copper. This magma is forced upwards through cracks in the rock.
As the magma rises it cools, and copper compounds crystallise as porphyry rocks.
Sedimentary Deposits
When water in the Earth’s crust is heated, it dissolves compounds of metals, including copper.
Sedimentary copper deposits form when this mineral-rich water flows through gaps in sedimentary rocks, e.g. shales and sandstones. Chemical changes cause the copper ore minerals to solidify in cracks and gaps in the rock.
When the copper reserves are exploited is affected by four factors
Richness of the reserve - the more copper an ore contains, the less rock has to be mined to produce the same amount of copper. This means that richer deposits are more cost-efficient to extract.
Extent of the reserve - whether there is enough copper to pay for the investment required to extract it.
Ease of extraction-e.g. reserves that are close to the surface are easier and cheaper to mine.
Location - if the ore is in a remote location, the cost of extraction is increased, as people, machinery and extracted ore have to be transported to and from the mine. If the country is politically unstable, mining companies may be unwilling to invest in mines there.
Open pit mining
Open-pit mining-surface material is removed before the ore is extracted layer by layer, leaving a huge hole. Open-pit mining is fairly cheap because it’s easy to mechanise and doesn’t require too much infrastructure.
Deep mining
Deep mining-shafts and tunnels are dug underground to extract the ore. Deep mining is expensive, so it’s generally only carried out when the copper deposits are too far below the surface for open-pit mining and contain enough copper to make the extra investment worthwhile.
Copper properties
Copper is a very versatile metal because of its properties -e.g. it’s a good conductor of heat and electricity, it can be precisely bent or moulded into shape and it’s resistant to corrosion. Copper can be combined with other metals to make alloys, e.g. brass, bronze.
This means it’s used in lots of different products. End uses include electrical wiring, pipes, roofing, cookware, coins and motors.
These products are used in many different areas:(industrial use(12%), Transport(12%), Infrastructure(15%), Construction(30%).)
Copper-Industry
Copper is used in almost every industry, e.g. construction, transport, electricity distribution this makes it very important.
Copper-related industries (e.g. mining, processing and manufacturing products containing copper) can be major contributors to a country’s economy. For example, in 2013, the copper industry accounted for 20% of GDP in Chile.
Industries are expanding as countries develop, so demand for copper is increasing. 4) Any decrease in availability or disruption to supply would damage industry and countries’ development.
Extraction of copper ore reserves causes sustainability issues
As the ores that contain the most copper are generally mined first, they run out first too. This means that companies have to mine larger amounts of ore to extract the same amount of copper, so the cost of extraction gets higher, more waste is produced and the environmental impact increases.
The influx of people seeking employment at copper mines can put pressure on existing local services such as doctors and schools. Once mines close down, settlements can be abandoned and communities broken up
Extraction of copper ore reserves causes sustainability issues-Contamination
Spills and leaks of toxic substances can contaminate local water supplies (see previous page). Metals don’t break down so this leads to long-term pollution of streams and rivers, threatening water security in the area.
Open pits cause sustainability issues-Extraction
Open pits take up huge areas of land. This destroys habitats and can reduce biodiversity. However, many countries require mining companies to restore the landscape once mining has finished.
Acid rain-Extraction
Exposed rock continues to react with air and water to produce acid for hundreds of years - continued management of mines is necessary even after mining has finished, in order to limit environmental damage.
Processing copper causes sustainability issues-Contamination
To extract copper from its ore, the ore is crushed, dissolved in acid, filtered and smelted (heated) at over 1000 °C. This produces large amounts of contaminated waste water. Waste water is stored in ponds, but it may be washed into local watercourses by heavy rainfall this can affect ecosystems and human health.
Processing copper causes sustainability issues-greenhouse gasses
Processing copper uses large amounts of energy. Many processing plants have their own power stations -they often rely on fossil fuels, which increase greenhouse gas emissions. Coal is also becoming more expensive, making copper processing plants less economical to run.
