Landfills are becoming large concentrations of materials like plastic, aluminum and other. What part of the process of mining landfills and processing the materials for new products, makes mining raw materials from the earth and processing them cheaper?
In: Economics
It’s efficient to mine and know what you’re getting. In a titanium mine, you can go through the kroll process which is a well defined set of reactions to separate titanium.
Plastics are a byproduct of oil and gas refineries. When you take gas from the grown, the hydrocarbons you get are useful in making plastics.
When you recycle from a landfill, you’re going to have to sort out a lot of things you don’t know what they are. Even worse, chemical separations may be more difficult because separating titanium from dirt may be easy, but separating titanium from dirt, plastic, other metals, may not be as easy. Second, it can take a lot of energy to separate the wanted items from the unwanted items. Recycling polyethylene is doable but recycling polystyrene is not cost effective.
Also, materials can be degraded in a landfill. Cardboard soaked with grease can’t be recycled into paper. Leaked gas could make things flammable where not expected.
One more reason, is that recycled plastics are of worse quality than new plastic. Recycled plastics go through wear and tear. If you bend a plastic like a mechanical pencil clip, it’ll turn white due to stresses on the material. That’s can’t easily be rearranged. Second is that melting a plastic can lead to undesirable cross links that make the polymer less valuable. A lot of purposes will require new plastics rather than recycled
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