Metal Extraction vs. Recycling: What is More Energy Efficient?

14 April 2023

Metal extraction from ores can be a highly energy-intensive process. As a matter of fact, the energy required to extract and refine metals can be so high that it can even generate a significant impact on the environment.

Recycling metals, on the other hand, is often touted as a more environmentally friendly alternative to metal extraction. However, is it truly more energy-efficient than the other?

The initial answer would often depend on several factors. These factors include the type of metal, the source of the material, and the utilised methods. Here is a more in-depth comparison between metal extraction and metal recycling.

Metal Extraction

Metal extraction involves the mining and processing of ores to extract the metals needed by a wide array of industries. The energy required for this process depends on several factors, which include the type of metal, the location of the mine, and the mining and post-mining methods used to complete the said process.

For instance, the production of aluminium from bauxite ore often requires a significant amount of energy since the process involves the extraction of alumina from bauxite ore with the help of a complex chemical process. The energy required to produce this specific metal from bauxite is estimated to be about 14,000 kWh/tonne of aluminium, which is already high.

Similarly, the production of steel from iron ore involves the use of blast furnaces, which need large amounts of energy to heat the furnace to the required temperature. The energy required to produce one tonne of steel is estimated to be about 20,000 kWh.

Metal Recycling

Metal recycling, alternatively, involves the recovery of metals from scrap or end-of-life products, such as cars, appliances, and building materials. The energy required for metal recycling depends on the type of metal and the recycling method.

The energy required for metal recycling, in fact, is significantly lower than that required for extraction. For instance, recycling aluminium only requires about 5% of the energy required to produce aluminium from its origin bauxite ore. Likewise, recycling steel only needs about 25% of the energy required to produce steel from iron ore.

However, the energy required for this process also depends on the source of the recycled material. For example, recycling aluminium from end-of-life or scrap products requires less energy than recycling aluminium from scrap generated during the manufacturing process.

Another factor that affects the energy efficiency of metal recycling is the method of recycling. Several methods can be used for metal recycling, which include mechanical recycling, pyrometallurgical recycling, and hydrometallurgical recycling.

Mechanical recycling involves the shredding and separation of metals from other materials in the scrap, while pyrometallurgical recycling involves the melting of metals and separating those with impurities. Ultimately, hydrometallurgical recycling utilises chemicals to dissolve the metals, which are then recovered through precipitation.

The energy required for each of these methods varies, and the most energy-efficient recycling method would still depend on the type of metal and the source of the recycled material.

Overall, the energy required for metal recycling will be mostly lower than the one needed for metal extraction. Even with varying factors that can somehow alter the energy requirements of metal recycling, it can still trump metal extraction when it comes to energy savings. It does not even harm the environment as opposed to the processes involved in metal extraction.

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