What mixtures can be separated by leaching?
Solid mixtures a soluble component can be separated by leaching.
Leaching is the process of extracting substances from a solid mixture by dissolving them in a liquid.
Some examples of leaching are
- Extraction of a metal from its ore
Low grade gold ore is spread in large piles or heaps in a lined pit. It is sprayed with a cyanide solution that percolates down through heap. Cyanide ion leaches gold from its ores by the reaction
Au + 2CN⁻ ⇌ Au(CN)₂⁻ + e⁻
The oxidizing agent (electron acceptor) is atmospheric oxygen.
O₂ + 2H₂O + 4e⁻ ⇌ 4OH⁻
- Extraction of sugar from beets
Long thin beet strips travel up a slope against hot water flowing down. Sugar diffuses out of the beets. The hot solution at the bottom contains 10 % to 15 % sugar.
- Extraction of natural oils
Organic solvents such as hydrocarbons, acetone, and ether extract oils from nuts, beans, and seeds.
- Extraction of pharmaceutical products
Many different pharmaceutical products are obtained by leaching plant roots, leaves, and stems.