10.1.5 Alternative Methods of Extracting Metals

Alternative Methods of Extracting Metals: Biological Methods of Extracting Metals

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Copper is a widely used metal that plays a crucial role in modern society. Traditionally, copper has been extracted from high-grade ores through large-scale mining operations. However, due to growing concerns about the depletion of copper reserves, industries are now exploring methods to extract copper from lower-grade ores. This has led to the development of new techniques, such as phytomining and bioleaching.

Copper and its Ores

Copper is one of the most extensively used metals on Earth, found in various applications such as:

Electronics: Due to its excellent electrical conductivity.
Alloys: Used to produce metals like brass and bronze with desirable properties.
Construction: For roofing and plumbing.
Art: In sculptures and decorative items. The global demand for copper has surged over the past century, driven by the growth of human civilisation. However, copper is a finite natural resource, meaning that once it is exhausted, it cannot be replenished. The increasing demand has raised concerns about the dwindling supply of high-grade copper ores, which are rich in copper content. To address this, industries are turning to low-grade ores, which contain a lower percentage of copper, leading to the development of novel extraction techniques.

Phytomining

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Phytomining is an innovative method that uses plants to extract copper from low-grade ores in the ground.

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The process involves:

Land Selection: Identifying areas with a high concentration of low-grade copper ores.
Plant Growth: Plants are cultivated on this land, where they absorb minerals, including copper compounds, from the soil.
Harvesting and Burning: Once the plants have grown, they are harvested and burnt. The resulting ash contains a higher concentration of copper compounds.
Copper Extraction: Copper is then extracted from these compounds.

Advantages:

Environmental Impact: Phytomining is less harmful to the environment compared to traditional mining. It avoids large-scale land destruction and reduces carbon emissions, as the carbon released by burning plants is offset by the carbon absorbed during photosynthesis.

Disadvantages:

Time-Consuming: Phytomining is a slow process, as it requires time for plants to grow sufficiently to contain useful amounts of copper compounds. Additionally, it may necessitate land clearance for plant cultivation.

Bioleaching

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Bioleaching is another method that utilises bacteria to extract copper ions from low-grade ores.

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The process works as follows: 5. Bacterial Action: Bacteria convert copper compounds in the ores into a solution known as leachate. 6. Copper Extraction: The leachate, rich in copper ions, can then be processed using electrolysis or displacement reactions to produce copper metal.

Advantages:

Green Process: Bioleaching produces no carbon emissions, as no fuels are burnt, and it requires less land clearance than phytomining. Additionally, it can be used on land that does not have high concentrations of low-grade ores.

Disadvantages:

Slow Process: Like phytomining, bioleaching is time-intensive, as bacteria need time to break down the ore and produce the leachate.

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Extraction of Copper from Copper Compounds Once copper compounds have been extracted using phytomining or bioleaching, the copper metal can be obtained through:

Electrolysis:

Process: A solution containing copper ions is subjected to a potential difference. The positively charged copper ions are attracted to the negative electrode, where they are reduced to form solid copper metal.
Result: Pure copper metal is collected for further processing and use.

Displacement with Iron:

Process: Scrap iron, being more reactive than copper, is used to displace copper ions from copper compounds in solution.
Result: Neutral copper metal is produced, which can then be processed further.

Alternative Methods of Extracting Metals Simplified Revision Notes for GCSE Edexcel Chemistry

10.1.5 Alternative Methods of Extracting Metals

Alternative Methods of Extracting Metals: Biological Methods of Extracting Metals

Copper and its Ores

Phytomining

Advantages:

Disadvantages:

Bioleaching

Advantages:

Disadvantages:

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