摘要 |
An improved process for recovery of precious metals such as gold or silver using novel ion exchange resins having aryl guanidyl functionality from aryl guanidine compounds having a pKa at 25 DEG C. less than 13 and preferably less than 12. The resins have improved elution properties compared to known guanidine reagents using caustic eluant solutions, particularly improved eluant solutions such as a mixture of sodium hydroxide and sodium benzoate. A selective elution of base metals may be carried out before elution of the precious metals from the resins having guanidyl functionality.
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