This follows the resignation of Tony Shearer, who had been at the company since August.
Orosur said it is now reviewing the composition of the board to ensure it is appropriately structured and it may make additional appointments in due course.
"I am delighted that the board has appointed somebody of the calibre of Rafael as interim chairman," said managing director Ignacio Salazar.
"The company has benefited from Tony's leadership and experience over the past nine months. I would like to thank Tony for his contribution to the company and wish him well for the future."
Last month the company launched a review of its operations at the San Gregorio mine in Uruguay after a steep fall in gold prices.
Pre-stripping work at San Gregorio was halted and, as a result, the Arenal Deeps underground mine is the mainstay of near-term production alongside the mining of reserves at Sobresaliente and Vaca Muerta later in the year.
Orosur said that because stoping started late at Arenal Deeps, production for the current year to the end of May will be lower than expected at approximately 63,000 ounces. Its previous target was a range of 63-68,000 ounces.
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