2. Deposition In order to check a condition for deposition ofgoldfrom HOS, water and ascorbic acid were added step by step. Intervals of each step are around 20 minutes. This graph shows variation of concentration for water and ascorbic acid in HOS with 0.175% ofgold. At 1st and 2nd steps, gold precipitation did not occur, however I 3- ion was lost. Deposition ofgold starts at high water content with making fine-grained particles.
Before application Rough experiments here indicates that; 1. HOS can be used to extract gold. 2. Dissolution rate ofgold reaches to the maximum in the first one hour. 3. It can be estimated 0.1mol ofgold can dissolve in HOS with I 3 - of 1mol. It means that gold can be dissolved up until around 0.1% order ofgold content in the system. 4. By using ascorbic acid, deposition ofgold is likely to be controlled by water content. Because ascorbic acid can be dissolve only in system including water.