Preg-robbing of gold in chloride-bromide solution
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Outotec (Finland) Oy
Aalto University, School of Chemical Technology, Department of Materials Science and Engineering
Riina Ahtiainen   

Outotec (Finland) Oy, Rauhalanpuisto 9, 02230 Espoo, Finland
Publication date: 2016-01-01
Physicochem. Probl. Miner. Process. 2016;52(1):244–251
One of the major issue in gold chloride leaching is a tendency of gold to either precipitate or adsorb on a carbonaceous matter in an ore, i.e. preg-robbing. This paper discusses issues related to a preg-robbing phenomenon in gold hydrometallurgy, specifically in gold chloride-bromide leaching. This phenomenon has been observed in the 1800s to decrease gold recovery during gold chlorination as well as the state-of-art of gold cyanidation processes. The experiments were conducted in order to study the preg-robbing phenomenon in chloride-bromide media. The tendency of preg-robbing was demonstrated by adding carbon in a non-preg-robbing ore. It was shown that the preg-robbing tendency in the chloride-bromide media was very strong. Addition of 0.01% w/w of carbon powder into the non-preg-robbing ore decreased gold recovery from 92 to 70% and addition 5% w/w of carbon decreased gold recovery to almost zero.