What mixtures can be separated by leaching?

1 Answer
Sep 12, 2014

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.