The new F-process (patent pending) is based on the ability of a number of elements to form volatile salts after their reaction with a fluorine-bearing agent. The volatilized salts then undergo selective condensation, producing high purity metal oxides (> 99.9%).

Of special interest is the recovery of the silicon and titanium oxides from refractory minerals containing precious and/or rare metals. At the initial stages of the process, fluorination causes liberation of precious metals (quartz, ilmenite, etc. - see schematic). The volatilized silicon and titanium are then converted to valuable oxides, while the non-fluorinated residue undergoes further refining to produce the precious/rare metals fraction. Additionally, the process allows recovery of a high purity metallic iron.

The major advantages of the F-technology are as follows:

• Process is continuous and can be easily automated;
• Involves relatively low temperature (<700 °C) and minimal number of steps;
• Not sensitive to particle size of the raw material;
• Active reagent is easy to handle and is reused in the process;
• Waste free.

The following example will explain the above in more detail:

A sample of the ore made up of separate mineral ingredients was taken for processing with the following characteristics:

click to enlarge

• Fraction size: 0.5 - 3.0 mm;
• Major oxides content: 58% Fe₂O₃; 26% SiO₂; 6% CaO; 6% AI₂O₃;
• Gold content: 13.9 g/t (locked in quartz).