抄録
In a series of studies on the development of dry and selective recovery process of gold, release behavior of gold from an incinerated sewage sludge ash was investigated at the temperatures from 100 to 1000℃under a chlorine gas stream. Gold was released from the ash above 600℃ and all gold was released to gas phase at 1000℃. When carbon was added to the ash, the initial release temperature of gold was reduced to 400℃ and all gold was transferred to both gas and carbon phases by 700℃. To control the reactions for gold of volatilization from the ash and capture by carbon, the mixture of ash and carbon was heated first to the terminal temperatures of 700 or 800℃ under a nitrogen gas stream. When reaching this temperature, the gas was changed to the chlorine and the mixture held at the terminal temperature for 1 h. By using this procedure, all gold was captured successfully by the carbon. No appreciable effects of surface area and type of the carbon were observed on the capture of gold. Gold was captured selectively and dispersed in the carbon matrix.
