Leaching process (solid-liquid extraction)

The presentation contain some useful materials about leaching process or solid-liquid extraction.

1. Leaching process Presented By : Asim Farooq [email protected] Department Bsc Engg Tech Chemical (SUIT) Peshawar

2. Table of Content Definition of leaching Example of leaching process Principle of leaching process Uses of leaching

3. Definition Leaching is a process of mass transfer that occurs by extracting a substance from a solid material that has come into contact with a liquid. In leaching, the liquid is very important as it facilitates the ability to remove (or extract) a given substance from a solid matrix (i.e. material).

4. Example A simple example is the making of green tea. Now relate the component used in the green tea to our definition. The green tea bag is our solid mixture. The green to be extracted is our desired substance. And the hot water is our liquid source.

5. Example

6. Example The process goes like that . To add hot water to a cup. And now steep the green tea bag into it. Not only the color changes but also the green is extracted from the bag into the cup. And after steeping some the take a sip from the cup there is not only hot water but a delicious green tea. Making tea is an ideal example of how leaching works.

7. Principle of leaching Leaching can be batch, semi batch, or continuous. It usually operates at an elevated temperature to increase the solubility of the solute in the solvent. Feed to a leaching system typically is solid, consisting of basically insoluble carrier material and a (usually desirable) soluble compound. The feed usually must be prepared by grinding or chopping. It is then mixed with a liquid solvent. The desired material dissolves (to some extent) and so leaves when the liquid is drawn off as overflow.

8. Uses of Leaching Process Typical users include In the metals industry for removing mineral from ores (acid solvents). In the sugar industry for removing sugar from beets (water is solvent). In the oilseeds industry for removing oil from soybeans, etc. (hexane or similar organic solvents).

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