A Study of Basic Iron Sulfate Formation and Control in the Autoclaving of Argentiferous Sulfide Gold Ore

Autoclave treatment of refractory sulfide gold ores oxidizes minerals, such as pyrite, containing gold that cannot be recovered through conventional cyanidation. Oxidation liberates the gold by putting iron into solution. At high temperature and pressure, the dissolved iron tends to precipitate. A problematic iron precipitate that may form is basic iron sulfate (BFS). In the gold industry, BFS is re-dissolved in a “hot cure” process. Two complicating factors occur within the hot cure. First, if there is silver in solution, it reacts with ferric sulphate to form a refractory precipitate, called silver jarosite; treatment in boiling lime solution near boiling temperatures can recover silver from silver jarosite. The second issue is the presence of other salts in solution which precipitate, preventing the formation of silver jarosite or co-precipitating with silver. The proposed research looks at characterizing the species that form through each step of the autoclave – hot cure – lime boil circuit, investigating the effects of feed composition on silver recovery, and adding complexing agents to avoid silver jarosite precipitation. The results of the project will determine whether this process can be commercially implemented to a range of ore bodies, with high recovery and no technical hiccups.

Faculty Supervisor:

Dr. David Dreisinger

Student:

Ajanthia Gunaratnam

Partner:

Barrick Gold Corporation

Discipline:

Engineering - other

Sector:

Mining and quarrying

University:

University of British Columbia