[pcurran871]

How would you define extract and raffinate from a process? Is it enough to say that extract is the desired product from a process and raffinate is the waste or is there a more detailed explanation?

[pcurran871]

Have I got this right or is too vague?

[mjc123]

From Wikipedia on "raffinate":

"In chemical separation terminology, the raffinate (from French raffiner, to refine) is a product which has had a component or components removed. The product containing the removed materials is referred to as the extract. For example, in solvent extraction, the raffinate is the liquid stream which remains after solutes from the original liquid are removed through contact with an immiscible liquid. In metallurgy, raffinating refers to a process in which impurities are removed from liquid material."

Which is the desired product and which the waste depends on the nature of the mixture, whether you "desire" the major or minor component, which component is more soluble/volatile etc. As "raffinate" literally means "refined", the term would seem to have originated in a process where a material is purified by having impurities extracted, but you can also have processes where the material you want is a minor constituent of a mixture from which you seek to extract it, e.g a precious metal in a ton of rock containing a small amount of ore. Note that, as defined above, the "extract" is the immediate product of the extraction, e.g. a solution in solvent extraction, not the final isolated product.