| 摘要 |
<p>A process for extracting metal values especially zinc values from aqueous solutions of metal salts which comprises contacting the aqueous solution with an organic phase comprising a compound of the formula: <CHEM> wherein each of R<1>, R<2>, R<3> and R<4>, independently, represents an optionally substituted hydrocarbyl or hydrocarbyloxy group or R<1> and R<2> together with the attached phosphorus atom and/or R<3> and R<4> together with the attached phosphorus atom form a 5- to 8-membered heterocyclic ring.</p> |
