Extracting metals from e-waste is one of the commonest practices for mobile phone recycling. Electronic devices consist of various types of precious and semi-precious metals which are recovered during refurbishment to be used later for other purposes. This is a very good use of extracts from e-waste because majority of the materials do not get wasted; instead they are used to serve other purposes. Sometimes, huge chunk of metals are recovered from recycling electronic gadgets.
Procedures to Recover Metals
Different procedures are followed while extracting metals from electronic waste. In the last post we had already highlighted some of the procedures, in this one we are going to talk about a few more. The processes include:
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Municipal Incineration- Incinerating the waste by municipal burners is an effective way of recycling. The metals get diluted after being heated at high temperature inside the furnace. After the metal is diluted, it is separated individually based on its density. A number of metals are present in the electronic devices and hence it requires extreme heat to be filtered out post dilution. VOCs, SVOCs, dioxins and halogens are usually separated. It is not the safest process and there is risk involved in it. Emission of hazardous gases like hydrogen bromide takes place while burning printed circuit boards.
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Open Flame Burning- This method uses acids to dissolve and extract metals from electronic waste. Developing nations like India and China follow these methods to extract metals and export them to countries like Australia, UK and USA. Not all metals can be recovered by this process. Gold, lead, copper, iron and lead can be extracted from old mobile phones.
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Plasma Arc Gasification- Superheated and electrically charged air stream is used to separate metals in this process. E-waste accumulated in huge containers is exposed to preheated air of 13900 degree Celsius or recovery. Molten glass is produced through this process which includes huge amounts of metals along with impurities. This process is generally used for small scale e-waste and energy generation. It cannot be used for high concentration of metals.
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Bioleaching- Bacteria and fungi are used in this advanced process of metal recovery. Bacillus So, Sacchormyces Cerelisiae and Yarrowia lipolytica aresome organisms used in this method to achieve results. These organisms can segregate copper, lead, tin from printed circuit boards after shredding into smaller pieces. The bacterium C.Violaceumis capable of dissolving 14% of gold from 10 mg of e-waste. T.Thiooxidans and T.Ferrooxidans bacteria can dissolve 90% of nickel, aluminum, zinc and copper from waste. However, these can only be separated after shredding the items.
This is the last batch of processes for extracting metals from e-waste. These processes are mostly for small scale use. However, an advanced method is also provided in the list which enables responsible use of old mobile phones. All these methods are helping the entire world to deal with e-waste and save the planet.
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