Abstract: The present invention provides a method for recovering rhodium sponge in high yield from ammonium hexachloro rhodate solution. The method comprises adding formic acid to ammonium hexachloro rhodate solution to reduce the rhodate, recovering reduced rhodium as rhodium black, and calcining the rhodium black under hydrogen atmosphere without water-washing to obtain rhodium sponge.

Abstract: Object: This invention provides a method of refining an Rh-containing solution also containing at least one type of impurities of heavy metals, alkaline earth metals, and Ag. Means for solving the problems: The invention provides a method of refining an Rh-containing hydrochloric acid solution also containing Ag and at least one other impurity of heavy metals and alkaline earth metals, the method comprising the steps of: (a) adding an alkali to the solution to adjust pH of the solution to 7-12, whereby generating a neutralized precipitate containing Rh and other components; (b) filtrating and separating the neutralized precipitate; (c) adding a first hydrochloric acid for redissolving the neutralized precipitate in an amount such that the mole ratio of Cl to Rh (mole ratio Cl/Rh) of a resulting solution becomes 3-4; (d) filtering the resulting solution to remove Ag as precipitate, and (e) extracting the solution obtained by the previous step as an aqueous phase with DEHPA.

Abstract: The present invention provides a method for recovering rhodium sponge in high yield from ammonium hexachloro rhodate solution. The method comprises adding formic acid to ammonium hexachloro rhodate solution to reduce the rhodate, recovering reduced rhodium as rhodium black, and calcining the rhodium black under hydrogen atmosphere without water-washing to obtain rhodium sponge.

Abstract: Means for solving the problems: The invention provides a method of refining an Rh-containing hydrochloric acid solution also containing Ag and at least one other impurity of heavy metals and alkaline earth metals, the method comprising the steps of: (a) adding an alkali to the solution to adjust pH of the solution to 7-12, whereby generating a neutralized precipitate containing Rh and other components; (b) filtrating and separating the neutralized precipitate; (c) adding a first hydrochloric acid for redissolving the neutralized precipitate in an amount such that the mole ratio of Cl to Rh (mole ratio Cl/Rh) of a resulting solution becomes 3-4; (d) filtering the resulting solution to remove Ag as precipitate, and (e) extracting the solution obtained by the previous step as an aqueous phase with DEHPA.